Taking the Founders Pledge to Donate to Charity Following a Liquidity Event

If there is anything worse than bragging about one's charitable giving, it is bragging about the charitable giving one might accomplish in the future, should one turn out to have the funds to do so. In a world in which establishing cultural norms wasn't so very important to success in non-profit fundraising, none of the audience here would know anything about my donations to the Methuselah Foundation and SENS Research Foundation, made over the years as we moved ever closer to the reality of therapies to treat and reverse aging. But establishing cultural norms is in fact very important in this business of non-profit fundraising. Why does cancer research receive such a large amount of non-profit funding? That has a lot more to do with the culture of charitable giving, and the visibility of giving to cancer research programs, than with the merits of those programs and organizations, or the merits of defeating these medical conditions. It is a great idea to fund effective cancer research, but I don't think that is why most donors give to the cause.

Even in small communities, such as the people who have supported work on rejuvenation biotechnology and other forms of development aiming at the treatment of aging as a medical condition, the broader success of fundraising depends upon as many individuals as possible visibly demonstrating their willingness to donate to the cause. It depends on people talking about it, normalizing the idea that this cause is a great one, and that donating is an eminently sensible action. It depends on those people then putting their funds where their mouths are, and making that a very public action. Obviously I jest when I talk about bragging about charitable donations, but talking loudly about charitable donations is a necessary part of ensuring that a meaningful number of people choose to donate.

The Founders Pledge is an initiative that attempts to make this process of cultural normalization of charitable giving more rigorous and effective in the (on balance) comparatively high net worth communities of entrepreneurs and their investors. If attending Founders Forum events, which are moderately selective for founders likely to succeed, or who have already succeeded, one will sooner or later meet the people who run the Founders Pledge. They would like to see all company founders sign up to donate to charity a meaningful fraction of their gains from an eventual liquidity event, the sale or IPO of the company. The founders choose the charities, the Founders Pledge organization offers resources to help make those choices effective, and the point of the exercise is that eventually this becomes the norm rather than the exception. A more charitable world is better than a less charitable world, given the sizable number of issues that tend to yield only to philanthropy at the outset - and the development of rejuvenation therapies was and continues to be one of those issues.

For me, the Founders Pledge is the Members Club of What I Was Going To Do Anyway, so of course I signed up. I am the cofounder of Repair Biotechnologies, and should the ongoing preclinical development efforts at that company result in a financial windfall for me at the end of the day, an outcome that is considerably less important to me than success in developing therapies that have a meaningful impact on aging, then I will give a third of my gains to charitable causes. Most likely the same organizations that I have supported in the past, the Methuselah Foundation, SENS Research Foundation, and other non-profits such as the Life Extension Advocacy Foundation that have arisen to speed development of rejuvenation research.

Given why the Founders Pledge exists, it would defeat the point for me to take this step and not tell everyone. So here I am, telling everyone. For the founders in the audience, give it some thought. This is a good initiative, and I'd like to think that many of you would also tend to see this as an affirmation of actions that you would have taken anyway. So take the leap.

Calorie Restriction Started in Old Age Does Not Extend Life in Mice

Researchers here establish that calorie restriction started in late life does not extend life in mice, contradicting older research results showing that it does to some degree. This may be a difference resulting from mouse lineage or housing or diet prior to applying calorie restriction. The researchers here point to the behavior of fat tissue in the older mice as being important, so we might think that perhaps the mice in the two studies began calorie restriction with differing amounts of fat tissue.

In any case this is a reminder that the practice of calorie restriction - and therefore treatments that mimic some of its effects - are a method of slowing aging, not reversing aging. For the full benefit to emerge, calories must be restricted, or the treatment applied, throughout much of life. This makes it a comparatively poor area of study when it comes to the development of human therapies to treat aging.

Mice live longer and are healthier in old age if they are given 40 percent less to eat after reaching adulthood than animals who are allowed to eat as much as they want. The dieting mice are fed with food enriched with vitamins and minerals to prevent malnutrition. But if food intake is first reduced in mice first start eating less food when they are already seniors, the researchers observe little or no effect on the life expectancy of the mice. On the other hand, when mice are allowed to eat as much as they like after a period of reduced food intake, they have no long-term protection, so reduced food intake has to be sustained for mice to reap the benefits. Reduced food intake must therefore be implemented early and be sustained until the end of their lives to have positive effects on health in old age.

But why do older mice no longer react to the change in diet? Researchers investigated gene activity in different organs. While the gene activity in the liver quickly adapted when mice are transferred to a restricted diet, the scientists observed a 'memory effect' in the fat tissue of older animals. Although the mice lose weight, the activity of the genes in the fat tissue is similar to that of the mice that continue to eat as much as they want. In addition, the fat composition in old mice does not change as much as in young mice.

This memory effect mainly affects mitochondria, the cells' power houses, which play an important role in the ageing process. Usually, reduced food intake leads to increased formation of mitochondria in fatty tissue. But the study showed that this is no longer the case when older mice are switched to a lower calorie diet. This inability to change at the genetic and metabolic levels may contribute to the shortened lifespan of these animals.

Link: https://www.mpg.de/14021239/1017-balt-110438-health-in-old-age-is-a-lifelong-affair

Senescent Cells Consume their Neighbors

The accumulation of lingering senescent cells is an important contributing cause of degenerative aging. In this intriguing report, researchers note that senescent cells resulting from chemotherapy treatment can consume neighboring cells in order to prolong their survival. This is most likely the case for senescent cells in general, whatever their origin. This cellular cannibalism is probably detrimental to tissue function to some small degree, but, since senescent cells are always a tiny minority of all cells, even in old tissues, it is nowhere near as detrimental as the inflammatory signaling profile that accompanies cellular senescence. Unless this consumption of nearby cells is absolutely vital to the survival of a large fraction of long-lived senescent cells, the mechanisms involved are unlikely to present a useful point of intervention.

Multicellular life requires individual cells to cooperate in a way that benefits the organism. Cells that are uncooperative because they are damaged or dysfunctional, and that pose a threat, are either eliminated by cell death or undergo a usually irreversible growth arrest called senescence. Senescent cells typically never divide (although there are some rare examples of cells exiting senescence and resuming division), but they can persist in tissues and contribute to ageing and cancer progression.

Senescent cells are metabolically active6, and this is characterized by their secretion of proinflammatory molecules as part of a phenomenon termed the senescence-associated secretory phenotype (SASP) response. Senescent cells can promote cancer progression and resistance to anticancer therapy in some contexts, as a result of the secretion, through SASP, of growth factors and immune-signalling molecules called cytokines.

Chemotherapy that damages the DNA of cancer cells can result in their death or their entry into senescence. Researchers investigated the effects of chemotherapy-driven senescence in breast cancer cells in mice. Under the microscope, they saw senescent cells eating and digesting entire neighbouring cells. This striking observation was made in breast tumours formed of mixtures of transplanted cancer cells, which were engineered to express red or green fluorescent proteins. It can be difficult to observe a cell being internalized by another cell in cancer tissues. By growing tumours with mixtures of fluorescently labelled cells, the authors could clearly identify red- or green-labelled cells being taken up into neighbouring cells labelled by the other colour.

Ingested cells are broken down in a digestive organelle called the lysosome. Crucially, senescent cells that ate their neighbours survived longer in vitro than those that did not. This finding suggests that metabolic building blocks retrieved from the lysosomal digestion of neighbouring cells were being used by senescent cells to promote their survival. The authors tested chemotherapy-induced senescent cells of other types of cancer, including lung cancer and a bone cancer called osteosarcoma, and found that these cells also cannibalize neighbouring cells. Together, these findings suggest that cell cannibalism might be an activity that is broadly associated with the induction of senescence, rather than being linked to particular types of cancer or to the status of proteins such as p53.

Link: https://doi.org/10.1038/d41586-019-03271-3

A Perspective on Longevity Biotech Investment from James Peyer of Kronos BioVentures

James Peyer, formerly of Apollo Ventures and now at the larger Kronos BioVentures, has a range of interesting views on the new and growing longevity biotechnology industry. Apollo Ventures was one of the earlier longevity-focused funds to emerge from the comparatively small community of scientists, patient advocates, and investors enthusiastic to accelerate progress towards the treatment of aging as a medical condition. The presentation here was given earlier this year at the Ending Age-Related Diseases conference organized by the Life Extension Advocacy Foundation.

In the matter of creating new medical therapies, there is a huge, well known, gaping chasm between academia and industry. Neither side of the chasm is all that good at the process of transferring promising projects from proof of principle in the laboratory to clinical development in a biotechnology company. Worthy projects languish and die because of this incapacity. This is a major issue for our community now that rejuvenation research, after the SENS model of repairing the underlying damage that causes aging, has come to the point at which projects are far enough along to begin commercial development. James Peyer's efforts represent one of the possible solutions to this challenge: a much more active venture funding community, one in which the investors do not wait around for entrepreneurs to show up at the door, but are specialists in the science themselves, capable of creating companies to carry forward promising research projects.

James Peyer | Biotechnology Investment

Hello, everyone. Many of you may know me from Apollo Ventures. Now, from a month or two ago forward, I will be affiliated with Kronos BioVentures. The switch here is not one of particular substance; we had to change an organization, I wanted to do a lot more investments, and do much bigger investments. So we went from Apollo to his grandfather Kronos, when we changed the name.

I am speaking towards the end of this event, so if I were to come up here and talk to you about the aging space or even the investment considerations, it would be a lot of repetition from other presentations today. So I wanted to do something slightly different with my time today, and it is going to be a little data-heavy, and a little bit different. We're going to do three things, that I will call a perspective, a prospect, and an approach. I'll cover, number one, some ways of talking about aging in this longevity biotech space, that I think a lot of us aren't necessarily thinking about, or it isn't the first thing that I usually hear. Then I want to talk about the present situation in biotech venture capital, particularly biopharmaceutical VCs. Then I want to talk about my favorite strategy in this space, both for biopharma VCs and for the longevity biotech space, which is VC-partnered venture building. Which is more than half of what I do - that's my hammer that I'm striking every likely-looking nail with, and then building a VC-backed company around it.

To dive in I have just about a dozen slides which I think are interesting perspectives on the aging space. I'm going to talk here about demographic, economic, and human health problems. I'm not going to touch on social solutions, because I think we're all here for the medical solutions. My first slide: it is important to remember that modern demographics present a new problem. This longevity issue that we're facing is quite a new thing to come to the forefront of people's minds. We are only now entering the fourth stage of what is called the demographic transition - as we go from a situation which is the natural state of humans, where we have very high birth rates and very high death rates. We then evolve through this population explosion that happens in stage two, towards a more stable population distribute in which birth rates and death rates are relatively low. We're just entering that stage.

So this issue of having old people around in large numbers, dying of diseases like cancer and Alzheimer's, and having complications like type 2 diabetes and osteoporosis, is a relatively new situation. One hundred years ago, the three leading causes of death for humanity were influenza, tuberculosis, and pneumonia. Today they are dementias, cancer, and cardiovascular diseases. This is the key thing in understanding the "why now" of the longevity space - that we are in the midst of this demographic transition.

To illustrate this a bit more, here are some projections based on the UN numbers. My favorite statistic in looking at demography is the old-age dependency ratio. This is the number of people 65 and older divided by the number of people younger than 65, the working age adults 15-64. What you can see, both in the developed world and the undeveloped world, is that these ratios are rising dramatically over this century. In 1950 we're at about 12% in the developed world, and we're going to be almost 50% by the end of the century. That is a huge change.

The important thing to remember here is that as we get all of these older people in our society, our society is not set up to support these people. So we come up with this economic problem, which is that, already, in the middle of this graph, the middle of this demographic shift, in the developed world we already have a crisis of underfunded pension obligations as we make commitments to people who can't work in old age - because they are going to get sick. This right now, according to Citibank, is about $78 trillion worldwide in unfunded or underfunded pension liabilities. I think you can make a credible case that they only way to prevent this incredible number from getting even bigger, and causing even more social and economic calamity, is by making people live longer and healthier, so that they can contribute more to society, even in the late stage of the demographic transition.

Next, from a human health perspective, many of you have seen variants of this graph, but I just wanted to do it with many more diseases, showing the incredible association of aging with all of the leading causes of death. This shows a normalized occurrence rate, so every year you have a chance of getting a heart attack, or getting cancer. So if you plot the chances of getting cancer this year, versus the highest chance you'll ever have in your life, what you'll see - for all of these diseases - is that the older you are, the higher your risk becomes. That is true for cardiovascular disease, Alzheimer's, Parkinson's, diabetes, and kidney disease.

Moving right along, one of the things that we don't talk enough about in the aging space, but is critically important to understand why we think the technologies that the longevity biotech world is developing will be so powerful, is the issue of multimorbidity. That is basically having more than one chronic condition at once that you have to deal with. What you can see here is that as people get older, as you move towards 75, by that age about 41% of all people have at least two chronic conditions - and many of them have more. Then that number goes up and up and up as you get older. So people aren't just dealing with their atherosclerosis, they are dealing with diabetes, with COPD, with senility, all at the same time. For that reason this great analysis, done by Dana Goldman and colleagues in 2013, shows that because there are all of these risks that come up together, if you just reduce risk and prevent one type of disease, let's say reducing cancer risk, or reducing heart disease risk, you get almost no extension in healthy life span. Almost none. Here 75 years is the base case, and 76 years is what you get just by reducing the risk of one type of disease. If, however, you reduce risk of all the age-related diseases together by a smaller amount, only then do you see a huge jump in life span.

So this was a little tour of some perspectives that I like when thinking about this space. The last one I'm going to leave you with before we jump to the more technical financing part is this graph of life expectancy in the US over time. These are the UN projections for average life expectancy over the next century. When I went back far enough in the data, these are really clear projections forward of the trend from about 1970, it is almost a straight line. But I think that what we are at the cusp of in in the development of technology around longevity biotech is much less like this period from 1970 to 2020, where we were just starting to understand what the diseases of aging were actually caused by, what molecular characteristics they have, and how to approach them. I think that our new situation is going to be much more like the period from 1910 to 1950, when we were actually conquering many of the infectious diseases that were the leading causes of death at that time. We spend perhaps 50 to 100 years characterizing the germ theory of disease and then developing tools like vaccines and antibiotics, and as a result saw a massive upswing in average life span. So my projection here is that as we conquer the diseases of aging we'll see a slope as new drugs come out that will be more similar to the earlier era in which we were conquering infectious diseases than in the later era when we were not making that much medical progress in treating aging.

Now on to the second part of the presentation. I'm going to show you six slides that will encapsulate what I think of biopharma VC space. We're all in this universe of the startup ecosystem in biotech, and I think that, especially as this little niche industry that hasn't launched many approved drugs, it is important to analyze what this bigger industry actually is, how it works, and what kind of success rates we should be expecting. I want to start with an overview of what the biopharma space is. These are companies that make drugs that go through clinical trials. That is most of what we do in the longevity space. There are a couple of interesting trends that have been happening in the biopharma space generally. The first is that the phase at which acquisitions are happening - most companies will ultimately get acquired by a pharmaceutical company, which will then run the latest stage trials and sell the drug - and those acquisitions have been happening earlier and earlier. You can see in the white line here, these are preclinical and phase I stage companies. Since 2013, the numbers of acquisitions of commercial and phase III stage companies have been going down.

So companies have been acquired earlier, but even though they are being acquired earlier, they are being acquired for larger amounts with less time spend in development of those companies. As an investor, these three facts are really exciting. It means that you are making more money, faster, and you have to do less work to get there. On the one hand that means this is a great time to be investing in biotech. On the other hand, it also makes investors worried.

Here is the second graph; most new drugs today come from biotech startups. This is a massive shift from what the world looked like twenty years ago. Twenty years ago you had the pharma companies that would either in-license stuff from academia, or they would do their own research and development to find drugs and approve those drugs. In 2017, 75% of all of the approved drugs came from biotech startups. Many of them were acquired and ultimately did the final trials with Big Pharma, but that is also a hugely defining factor. That means that the vehicle of choice for getting an approved drug is a biopharma startup.

Thirdly: drugs that come from startups do better in the clinic than drugs from Big Pharma. There is something that I find absolutely magical about the ability to take a very dedicated team of founder and founding scientist and throw them into a problem and say, alright, you guys need to get this thing to work. Your company, and everything that comes with it, many times reputation, many times validation of the scientific theory, all rides on getting this question right and answering this question in the right way. That pays off in the long term, because when drugs ultimately launch, it is almost twice as good for a drug to start in a biotech startup and be licensed to Big Pharma when compared to internal development in Big Pharma.

Fourth: total amounts of VC funding per round have been going up enormously in the last couple of years, particularly in 2017 and 2018 - I have the medians and the means graphed here. This chart shows average size per round, and you can see that in 2018 that series A and series B rounds for average biotech companies were around $30 million. That is a lot of money. Seed rounds, however, are staying relatively small - $2-3 million is the normal there.

Fifth: IPO valuations have been going up and up and up for preclinical and phase I stage assets, but not for phase III. Before I get to my last piece, I want to close on this overview of where we are in the biotech investment space. You can draw two conclusions as you look at these five pieces of data. The first conclusion is that this is absolutely the time to be doing a biotech startup in innovative drug development. The second conclusion is that this looks a lot like a bubble. If you look at the macroeconomic situation, starting from where a lot of my data starts, from 2011 until now, the stock market has been riding high, we've been in this expansionary economy. So a lot of investors who are thinking about, today, where I want to commit my money for a drug development program, they have to think about how is this market going to look three, four, five, ten years in the future. There are some worrying signs, for us, that we have to be taking this risk of a bubble in biotech very seriously.

One of the signs that is most apt is this graph. For those of you who don't know, 2018 was the biggest year ever for IPOs in biotech companies. There were over 60 IPOs. However, something a little bit disturbing came along with these IPOs. On this graph, each company is a bar, and the size of the bar indicates what percentage change their stock has had between their IPO in 2018 and the end of 2018. You can see that more than half of them declined - and a lot of them declined by a lot, in less than a year. What this means to me is that the public markets are really, really harsh on these early stage biotech companies. Because there is an exuberance, many companies are jumping into the public markets without having to show any more data. Now that they are subject to public scrutiny, by people who aren't trading on the potential of the company, but instead on what has the company done, they get hammered. This makes private investors, long term investors to fund clinical development that much more important. Potentially more important than it has ever been. It also means that investment going forward in the next five to six years is probably going to have to be more disciplined. I don't think that this IPO window, with high valuations and freely available funds, is going to last.

That leads me to five quick conclusions about the biotech VC space. Number one, avoid exuberance as much as possible. Number two, focus on seed investments, getting in really early, as round sizes are not increasing there. Getting in early and following things through, the timing and the amounts make a lot sense. Number three, don't plan for the IPO ecosystem to continue the way it has been. Number four, only exit when you have a clear value story, and you are confident that you can actually back away from the project. Don't just throw it out into the world and see how it goes. Number five, and this is important, there are some cautionary things here, but I think that, overall, the trend that we've been seeing in the biotech ecosystem will continue.

I didn't spent time on the data here, but the main reason that a lot of this boom has been so exaggerated is that Big Pharma research and development is changing fundamentally. Resources are going away from the Big Pharma companies doing research and development into biotech startups. That space that is being created, it isn't being filled fast enough. So even though there are a lot of resources going into it, and there is a lot of excitement, Big Pharma companies still desperately need their pipelines to be filled - and filled with good drugs. So this space will continue to grow, as this trend continues in moving to this more efficient method of creating drugs in biotech startup companies.

My last piece that I want to do, very quickly, is just a little bit on my approach to how to play in this world, and how I've been working with scientists and entrepreneurs to do this. This is a venture-led company building process, where I think that there are five key things that a company needs to do in order to pull together their story and become a real biotech company. Number one, you identify exceptional research, and in our case it is longevity research. Number two, you partner with the people who know the science intimately, and never do a company without the scientists that know what they're talking about. Work with the scientists that know the science, because when you run into trouble, and you will always run into trouble when doing basic research, they are the only ones who have run into the same thing ten times before, and know the answers to what is going on. It will slow down a company enormously if you don't have those guys.

Number three, biotech is a bit unique compared to the tech world in how different the different phases of a company are as it progresses through its value chain. The guy who knows how to get toxicology studies done and the guy who knows how to correctly do a phase III clinical trial and the guy who knows how to successfully sell a drug on the marketplace are completely different from the guy who knows how to make a basic discovery in fruit flies. So having a team that comes in at the appropriate time to lead this process at the right time for that company is a characteristic of the best biotech companies that I know. One of the reasons that I want to focus on this VC-led or this company building model, and why I think it works so well, is that you have people in the board of directors or who helped to create the company that exist somehow behind the operational team, and the operational team can be led by a different person, whoever is needed the most for that phase of the company. But the overall mission and vision and science of the company can be supported by the founders all the way through, which is a model I really love.

Number four, you have to design your key value creating experiments, like what is the killer experiment, without this there is nothing. Then do that experiment and fail fast if you are going to fail. Then number five, biotech development is very expensive. You need to have a path to $20 million or $30 million rounds to do clinical trials. If you don't think that you'll be able to raise that money, then you need to have a partner on board early on who you think can.

Next slide, and I'm not going to spend a lot of time on this, in company building we do things in three phases. My favorite way of looking at building companies is in a hypothesis-led way. Whether you are an entrepreneur or a venture investor this, I think, should be the start: come up with a hypothesis. Then explore, validate the hypothesis, get the people on board, and then create the company. Then my last slide; it is easy to focus in on Silicon Valley and Boston as the two largest biotech hubs in the world. I think that doing so leaves so much on the table. Great basic research can be found everywhere in the world. There are fantastic institutions in Europe, in Southeast Asia, in the center of the United States that are underexplored. So a big part of what I do at Kronos is to look around at where that great research is done, and then move forward wherever it is, with a team that can actually accelerate it.

So anyway, that is a bit of my perspective on the longevity biotech space. Thank you for your attention; hopefully some of you found this useful information.

Quercetin Coated Nanoparticles Shown to be Senolytic in Cell Cultures

Quercetin, while used in combination with dasatinib as a senolytic therapy capable of destroying senescent cells, is not meaningfully senolytic on its own. One argument as to why this is the case is that compounds of this class are not very bioavailable - in other words that quercetin, suitably modified, or delivered in a different manner, would be senolytic enough to form a basis for therapy. Researchers here take the approach of coating nanoparticles with quercetin molecules, and find that the resulting particles can selectively kill senescent cells in cell culture, unlike quercetin alone. This is a promising demonstration, particularly if we consider that it might be applied to the much more senolytic flavenoid fisetin, but it is always best to wait for animal data before becoming too excited by any given approach.

Cellular senescence may contribute to aging and age-related diseases and senolytic drugs that selectively kill senescent cells may delay aging and promote healthspan. More recently, several categories of senolytics have been established, namely HSP90 inhibitors, Bcl-2 family inhibitors and natural compounds such as quercetin and fisetin. However, senolytic and senostatic potential of nanoparticles and surface-modified nanoparticles has never been addressed.

In the present study, quercetin surface functionalized Fe3O4 nanoparticles (MNPQ) were synthesized and their senolytic and senostatic activity was evaluated during oxidative stress-induced senescence in human fibroblasts in vitro. MNPQ promoted AMPK activity that was accompanied by non-apoptotic cell death and decreased number of stress-induced senescent cells (senolytic action) and the suppression of senescence-associated proinflammatory response (decreased levels of secreted IL-8 and IFN-β, senostatic action). In summary, we have shown for the first time that MNPQ may be considered as promising candidates for senolytic- and senostatic-based anti-aging therapies.

Link: https://doi.org/10.1016/j.redox.2019.101337

Low Dose Quercetin as a Geroprotector in Mice

Quercetin is used in combination with dasatinib as a senolytic treatment capable of selectively destroying senescent cells, but quercetin used by itself is not meaningfully senolytic. Researchers here show that long term low dosage with quercetin modestly slows aspects of aging in mice, however, without extending life span. They evaluate a number of potential mechanisms, including possible reductions of the inflammatory signaling secreted by senescent cells. All in all an interesting paper, particularly for the investigation of effects on retrotransposons. I expect that most interventions shown to slow aging will turn out have some impact on retrotransposon activity, but that has yet to be investigated rigorously.

Quercetin (Que) is a natural bioflavonoid. Que (50 mg/kg) in combination with dasatinib (5 mg/kg) (abbreviated as D + Q) has been shown to effectively eliminate senescent cells via induction of apoptosis, thus alleviating senescence-related phenotypes and improving physical function and lifespan in mice. We recently identified Que as a geroprotective agent that counteracts accelerated and natural aging of human mesenchymal stem cells (hMSCs) at a concentration of as low as 100 nmol/L, which is 100 times lower than the concentration of Que (10 μmol/L) previously used in combination with dasatinib.

To explore the geroprotective effect of low-dose Que in rodents, we evaluated the in vivo effect of long-term low-dose Que administration under physiological-aging condition. Que was given to 14-month-old C57BL/6J male mice by weekly oral gavage at a concentration of 0.125 mg/kg body weight, which is 80-400 times lower than that of the previously tested D + Q (10-50 mg/kg body weight) regimens. After eight months of treatment, Que-treated mice showed decreased hair loss with normal food intake, body weight, blood glucose and bone mineral density. Compared to control mice, mice subjected to Que treatment showed markedly improved exercise endurance. However, the lifespan was not prolonged by low-dose Que treatment observed up to the age of 31 months. Taken together, these data indicate that long-term low-dose Que administration alone sufficiently improves multiple aspects of healthspan, but not lifespan, in mice.

To investigate how Que improved healthspan in mice, we collected 11 different kinds of tissues from 10-week young male mice (Y-Ctrl) and control (O-Veh) and low-dose Que-treated 22-month old male mice (O-Que). Given that exercise endurance and diastolic function were improved by Que, we particularly examined the changes in skeletal muscles (SKM), white adipose tissues (WAT), brown adipose tissues (BAT) and hearts. Upon Que treatment, the arrangement of muscle fibers became more regular and compact with less fibrosis and senescence. In WAT, the increases in adipocyte size and senescence-associated β-galactosidase (SA-β-Gal)-positive area during aging were both alleviated upon Que treatment.

We previously observed that Que alleviates hMSC senescence in part through the restoration of heterochromatin architecture in prematurely and physiologically aging hMSCs. Constitutive heterochromatins are predominantly comprised of repetitive elements (REs), including retrotransposable elements (RTEs). The expression of RTEs is repressed via epigenetic regulation under normal conditions but is elevated during physiological aging, eliciting active transposition. Accordingly, mobilization of RTEs is likely to be a key contributor to tissue aging innate immune responseand cell degeneration. To test whether Que treatment may also repress activation of RTEs in a mouse in vivo model, we compared the transcriptional levels of RTEs in multiple tissues of Y-Ctrl, O-Veh, and O-Que mice. Consistently, most RTEs were transcriptionally upregulated in the SKM and BAT of old mice compared to those of young mice and were repressed by Que treatment.

In senescent cells, the activation of RTEs leads to genome instability, which subsequently promotes senescence-associated secretory phenotype (SASP). Consistently, the inflammatory cytokine IL-6 was increased in old mice compared to young mice and Que antagonized the increase of IL-6 in both hMSCs and old mouse SKM and BAT. Thus, our data suggest that Que may block SASP through the axis of heterochromatin-RTEs-innate immune response pathway. Our data provide important evidence supporting the role of low-dose Que in safeguarding genomic stability (i.e. inhibition of retrotransposition), which at least in part contributes to its geroprotective activity in rodents.

Link: https://doi.org/10.1007/s13238-019-0646-8

Evidence for Human Cell Division Rates to Decrease with Age

We humans exhibit a peak cancer incidence in old age, around the early 80s, after which cancer rates decline from that peak. If aging is the continual accumulation of damage, then why do we observe this pattern of cancer incidence with age rather than a continual increase over time? It does not occur in mice, after all. Researchers here provide evidence for the explanation to involve reduced rates of cell division in later life, which may be one of many evolutionary adaptations connected to the unusual longevity of our species when compared with other similarly sized mammals, and particularly other primates. If there is less cellular replication, then potentially cancerous mutations will occur less frequently and spread less rapidly.

The divergence of human longevity from other primates is thought to have its origin in our culture and intelligence. Once it became possible for older members of society to contribute meaningfully to the fitness of their descendants, then there is selection pressure for longer life spans; this is expressed in the the Grandmother Hypothesis. Since human culture and longevity are comparatively recent developments in evolutionary terms, we might expect to find comparatively simple aging-related differences between humans and other mammals in the behavior of cells and tissues in the aged environment. Changes in stem cell behavior, or changes in cell replication rates in a damaged environment, for example: alterations that reduce the risk of death by cancer at the cost of a drawn out decline into loss of function.

Novel Study Documents Marked Slowdown of Cell Division Rates in Old Age

In a novel study comparing healthy cells from people in their 20s with cells from people in their 80s, researchers say they have documented that cell division rates appear to consistently and markedly slow down in humans at older ages. The researchers say the findings may help explain why cancer - long considered a disease of aging, with incidence highest among people over age 65 - has been found to decelerate in occurrence at the extreme end of human life. The findings, they say, also provide clues about cell biology that might eventually lead to a better understanding of cancer.

Cancer is spurred by an accumulation of genetic mutations caused by mistakes cells make when copying DNA during cell division. Research in the last several decades assumed that such mutations accumulate over time at a steady rate. However, when researchers reanalyzed old data in dozens of published papers, they found that mutations accumulate more slowly in old age. That analysis led researchers to suspect that cell division rates slow down markedly in old age, giving cells fewer chances to accumulate DNA mistakes.

To test this hypothesis, the team analyzed cell replication rates in samples of various healthy tissues collected during biopsies and other medical procedures from more than 300 patients in their 20s and in their 80s. Their findings showed that cell division rates slowed by about 40% in colon tissue samples collected from patients in their 80s compared with those in their 20s. Similarly, in samples of esophageal tissue, the division rate slowed by about 25% in the elderly compared with the younger patients. In the duodenum, at the beginning of the small intestine, the rate slowed by 26% in the elderly, and in posterior ethmoid sinonasal tissue, found near the nose, the rate slowed by 83% in the elderly.

When researchers performed a similar analysis of cell replication using tissue from young and old lab mice, they found no significant differences in the division rate - a considerable distinction between mice and humans that could make it more difficult to use aging mouse data as a proxy for aging humans.

Cell division rates decrease with age, providing a potential explanation for the age-dependent deceleration in cancer incidence

A new evaluation of previously published data suggested to us that the accumulation of mutations might slow, rather than increase, as individuals age. To explain this unexpected finding, we hypothesized that normal stem cell division rates might decrease as we age. To test this hypothesis, we evaluated cell division rates in the epithelium of human colonic, duodenal, esophageal, and posterior ethmoid sinonasal tissues. In all four tissues, there was a significant decrease in cell division rates with age. In contrast, cell division rates did not decrease in the colon of aged mice, and only small decreases were observed in their small intestine or esophagus. These results have important implications for understanding the relationship between normal stem cells, aging, and cancer. Moreover, they provide a plausible explanation for the enigmatic age-dependent deceleration in cancer incidence in very old humans but not in mice.

A Role for Acetylcholine in Sarcopenia

It has been suggested that some fraction of sarcopenia, an age-related loss of muscle mass and strength leading to frailty, is caused by dysfunction of neuromuscular junctions, the points of integration between muscle and nervous system. This is as opposed to the more straightforward loss of stem cell function, leading to a lesser capacity for muscle growth and tissue maintenance. Acetylcholine has a prominent role in the function of neuromuscular junctions, and on this basis researchers here demonstrate that reduced levels of acetylcholine lead to both improvement in the structure of neuromuscular junctions and a slowing of the progression of sarcopenia in aged mice.

In addition to driving contraction of skeletal muscles, acetylcholine (ACh) acts as an anti-synaptogenic agent at neuromuscular junctions (NMJs). Previous studies suggest that aging is accompanied by increases in cholinergic activity at the NMJ, which may play a role in neuromuscular degeneration. In this study, we hypothesized that moderately and chronically reducing ACh could attenuate the deleterious effects of aging on NMJs and skeletal muscles. To test this hypothesis, we analyzed NMJs and muscle fibers from heterozygous transgenic mice with reduced expression of the vesicular ACh transporter (VAChT), VKDHet mice, which present with approximately 30% less synaptic ACh compared to control mice.

Because ACh is constitutively decreased in VKDHet, we first analyzed developing NMJs and muscle fibers. We found no obvious morphological or molecular differences between NMJs and muscle fibers of VKDHet and control mice during development. In contrast, we found that moderately reducing ACh has various effects on adult NMJs and muscle fibers. VKDHet mice have significantly larger NMJs and muscle fibers compared to age-matched control mice. They also present with reduced expression of the pro-atrophy gene, Foxo1, and have more satellite cells in skeletal muscles. These molecular and cellular features may partially explain the increased size of NMJs and muscle fibers. Thus, moderately reducing ACh may be a therapeutic strategy to prevent the loss of skeletal muscle mass that occurs with advancing age.

Link: https://doi.org/10.3389/fnagi.2019.00262

The Collapse of Proteostasis in Later Stages of Aging

Proteostasis is the name given to successful maintenance of youthful levels of proteins and minimal protein damage in cells. With age, the molecular damage of aging leads to changes in expression of proteins and dysfunction in cellular maintenance processes. The result is ever more damaged proteins and altered cellular behavior. Some of those behavioral changes are compensatory, some cause further disruption to cell and tissue function. Loss of proteostasis is a hallmark of aging, but it isn't a root cause of aging. It is a downstream consequence of forms of damage that change cell behavior and impede the operation of cellular maintenance via autophagy or the ubiquitin-proteasome system.

In higher organisms, cells age and die by natural processes. What are the molecular mechanisms that drive it? It has been difficult to disentangle causes from effects because aging impacts most cellular biomolecules. Oxidative damage is known to play a key role. Much of what is known about cellular aging comes from "bottom-up" experiments, by perturbing a few genes at a time - by knockouts, knock-ins, or point mutations, or by gene-to-gene comparisons using sequence databases. Our interest here is in the "top-down" question of the aging mechanism, which we take to be a more system-wide failure in the cell. Any single gene cannot reverse aging or abolish life span limits. Oxidative damage is indiscriminate and nonspecific in which class of biomolecule it hits or its spatial location in the cell. We take the mechanism of aging and longevity to be more about a general and stochastic destruction than a pinpoint action.

One view is that aging results from declining protein quality-control systems involved in protein synthesis, degradation, and chaperoning that normally protect the proteins in the cell's proteome. Central to proteostasis, the decline in protein quality control is implicated in more than 50 diseases of abnormal protein deposition (proteinopathies), for which the principal risk factor is advancing age, probably because cell regulation and protein production and disposal becomes increasingly compromised with age. Proteostasis is a natural culprit in aging because it is a front line of response to stress and because proteins are the primary repairers of the cell and sustainers of the genome.

Here, we model how proteostasis - i.e., the folding, chaperoning, and maintenance of protein function -ncollapses with age from slowed translation and cumulative oxidative damage. Irreparably damaged proteins accumulate with age, increasingly distracting the chaperones from folding the healthy proteins the cell needs. The tipping point to death occurs when replenishing good proteins no longer keeps up with depletion from misfolding, aggregation, and damage. The model agrees with experiments in the worm Caenorhabditis elegans that show the following: Life span shortens nonlinearly with increased temperature or added oxidant concentration, and life span increases in mutants having more chaperones or proteasomes. It predicts observed increases in cellular oxidative damage with age and provides a mechanism for the Gompertz-like rise in mortality observed in humans and other organisms. Overall, the model shows how the instability of proteins sets the rate at which damage accumulates with age and upends a cell's normal proteostasis balance.

Link: https://doi.org/10.1073/pnas.1906592116

NLRP3 Knockout Extends Maximum Life Span by 29% in Mice

Today's open access research is an interesting demonstration of the importance of chronic inflammation in aging. Researchers generate a mouse lineage in which the NLRP3 gene is deleted, and show that these mice live significantly longer, and in better health, as a result. The protein produced from the NLRP3 gene is important in the innate immune response; it is a component part of one of the inflammasomes, protein complexes with a central role in regulation of the inflammatory response. NLRP3 appears important in the inflammatory signaling generated by senescent cells as well.

Inflammation is a necessary part of wound healing and defense against pathogens, among other processes. It isn't plausible to build a better mouse by simply disabling large parts of the immune response, as is reported here. Such mice can live longer in ideal circumstances, but probably won't do very well in a natural environment. The utility of this sort of research is not as a blueprint for human therapy, but rather to provide some idea as to the size of benefits that might be realized through success in addressing the problem of chronic inflammation in aging.

Periodic removal of senescent cells via senolytic therapies is the first concrete step forward to an old age free from chronic inflammation. These errant cells grow in number with age, and their secretions drive a sizable fraction of age-related chronic inflammation. Then we might look to methods of restoring a youthful immune system: restoration of the thymus, replacement of the hematopoietic stem cell population, and clearing out the malfunctioning immune cells that accumulate over the years. There are other mechanisms beyond these that may also be significant in spurring inflammation in aged tissues. Given the means to address them, old age might be made far less terrible.

NLRP3 inflammasome suppression improves longevity and prevents cardiac aging in male mice

Markers of inflammation have been associated with cardiovascular diseases and proposed as other cardiovascular risk factors. Recently, the role of the NLR family pyrin domain containing 3 protein (NLRP3) inflammasome has been studied in cardiovascular diseases. NLRP3 inflammasome is upregulated after myocardial infarction, atherosclerosis, ischemic heart disease, diabetic cardiomyopathy, chronic heart failure, and hypertension, and recently, NLRP3 and IL-1β have also been proposed as new cardiovascular risk biomarkers.

Previous studies have suggested a role for NLRP3 inflammasome in several events associated with aging. Genetic deletion of NLRP3 in mice has been shown to improve healthspan by attenuation of multiple age-related degenerative changes, such as glycemic control, bone loss, cognitive function, and motor performance. Furthermore, the deletion of NLRP3 in old mice increased muscle strength and endurance and prevented from age-related increase in the number of myopathic fibers. However, the role of the NLRP3 inflammasome in lifespan and cardiac aging has not been studied. Hence, we sought to determine whether or not genetic deletion of NLRP3 may have effect on lifespan and potentially prevent cardiac aging.

To evaluate the impact of NLRP3 deletion on survival and metabolic changes during aging, we followed NLRP3 deficient (NLRP3 -/-) and NLRP3 +/+ littermate control wild type (WT) mice throughout the entire lifespan. The survival of NLRP3 -/- mice compared to littermate controls was augmented with an increase in mean lifespan of 34% and in maximum lifespan of 29%, while body weights and food intake did not differ between the two groups during the entire observation period. Fasting blood glucose and circulating IGF-1 levels were reduced in young and old NLRP3-/- mice, indicating that the insulin sensitivity of these animals was considerably higher than sham controls during aging. Reduced levels of glucose and IGF-1 have been associated with stress resistance and an antiaging effect.

Heart weight normalized to body weight was increased in old mice in comparison with young mice, and heart weight was higher in WT in comparison with NLRP3-/-. Cardiac hypertrophy measured by the left ventricular wall thickness was significantly increased in elderly WT when compared to NLRP3-/- mice. From electron microscopic analysis, we corroborated that the numbers of accumulated autophagosomes were reduced in hearts from NLRP3-/- old mice. This could be explained by where NLRP3 inhibition induced improved autophagy quality in the heart during aging.

Early Detection of Misfolded Amyoid-β in the Blood Implies Greater Risk of Later Alzheimer's Disease

In recent years, a great deal of effort has been put towards means of assessing risk of Alzheimer's disease as early as possible in aging individuals. The results here are an illustrative example of initiatives focused on amyloid-β in the blood: assays based on a blood sample are somewhat easier to develop than most of the other options; amyloid-β levels in the brain are known to increase slowly over time; and the presence of amyloid-β in the brain and bloodstream are in some form of dynamic equilibrium with one another.

There is currently still no effective treatment for Alzheimer's disease. For many experts, this is largely due to the fact that the disease cannot be clinically diagnosed until long after the biological onset of disease when characteristic symptoms such as forgetfulness appear. However, the underlying brain damage may already be advanced and irreversible by this stage. "Everyone is now pinning their hopes on using new treatment approaches during this symptom-free early stage of disease to take preventive steps. In order to conduct studies to test these approaches, we need to identify people who have a particularly high risk of developing Alzheimer's disease."

In patients with Alzheimer's disease, misfolding of the amyloid-β protein may occur 15-20 years before the first clinical symptoms are observed. The misfolded proteins accumulate and form amyloid plaques in the brain. A new technique can determine whether amyloid proteins are misfolded in blood plasma, and researchers have demonstrated that misfolded amyloid-β in the blood correlates with plaque formation in the brain.

Researchers reexamined blood samples collected as part of the ESTHER cohort study, looking at 150 ESTHER participants in whom dementia was subsequently diagnosed during the 14-year follow-up period. These samples were compared with those of 620 randomly selected control participants not known to have been diagnosed with dementia who correlated with the dementia participants in terms of age, sex, and level of education. Participants with amyloid-β misfolding had a 23-fold increased odds of Alzheimer's disease diagnosis within 14 years. In patients with other types of dementia, such as those caused by reduced blood supply to the brain, the study did not demonstrate an increased risk, supporting Alzheimer's disease specificity.

Link: https://www.dkfz.de/en/presse/pressemitteilungen/2019/dkfz-pm-19-46-Protein-misfolding-as-a-risk-marker-for-Alzheimers-disease-up-to-14-years-before-the-diagnosis.php

Melanocytes are the Only Epidermal Cells to Show Signs of Senescence with Aging

Lingering senescent cells arise in every tissue, and their presence is a cause of aging. These errant cells secrete a potent mix of molecules that rouse the immune system to chronic inflammation, degrade tissue structure, and change the behavior of surrounding cells for the worse. The more senescent cells, the worse the effects. Researchers are beginning to look more closely at cellular senescence in aging skin, and the results from the study noted here are particularly interesting. That melanocytes are the only skin cell type to show the canonical signs of senescence is unexpected.

Nonetheless, the negative effects of senescence still exist in this case, and reinforce the expectation that senolytic drugs that reach the epidermis sufficiently well will be capable of reversing skin aging to some degree, just as they have been shown to reverse measures of aging in other organs. Given the present state of knowledge, I expect the benefits of senolytic therapies on skin to be minimal until later life. The skin aging that occurs between 20 and 50 is probably not driven to any great degree by senescent cells, as senescent cell burden most likely scales with age in a similar manner to cancer risk. There will no doubt be clinical trials in the years ahead, and firm numbers where today there are only expectations, but skin aging isn't all that high on the priority list for most of the companies and research groups working in the field.

Over time, cells in the body can be damaged by external exposures, like ultraviolet radiation from the sun, or internal ones like oxidative stress. On the skin this appears as wrinkles, dryness, or age spots. In the skin, changes occur so the outermost layer called the epidermis gets less nourishment, becomes thinner and is easier to breach. To understand this process on a cellular level, researchers began looking at different cell populations in skin to see if any cell type was associated with skin damage more so than another.

The team initially thought that one type of cell that is abundant in skin and divides often, called keratinocytes, would drive senescence. However they report that melanocytes, the cells which produce the pigment responsible for skin color, fit the senescence profile and released pro-inflammatory factors that could affect surrounding cells and induce skin aging. "Melanocytes divide very little throughout our life and constitute 5-10% of the cells in the basal layer of the epidermis. They showed a variety of molecular markers of cellular senescence in the aging skin. We found that melanocytes became senescent without telomere shortening, which is not surprising since they hardly divide. But melanocytes showed DNA damage specifically at telomere regions irrespectively of their length due to oxidative stress."

To confirm that melanocytes were really the driver of skin aging, the team built a 3D human epidermis in the lab, and found that melanocytes alone could induce several features of skin aging in the model. They also reported that the effect of the senescent melanocytes could be moderated by treating the model with the senolytic drug ABT-737 or by the mitochondrially targeted antioxidant MitoQ that protects mitochondria.

Link: https://discoverysedge.mayo.edu/2019/10/21/researchers-identify-cells-that-drive-human-skin-aging/

The Resurrection of Aducanumab Doesn't Change the Picture for Amyloid-β Clearance in Alzheimer's Disease

It took a long time and many failed attempts for the research community to get to the point at which amyloid-β could be successfully cleared from the brains of Alzheimer's patients. Unfortunately, the data to date strongly suggests that this isn't an effective approach to therapy, at least not on its own, even though it is clearly the case that the increased levels of amyloid-β in the aging brain should be removed. It is a characteristic difference between old brain tissue and young brain tissue, and there is plenty of evidence for it to be harmful.

This failure to achieve clinical success may be because amyloid-β aggregation ceases to be an important factor in later stage disease, once tau aggregation and neuroinflammation are firmly established. It may be because patients frequently have other neurodegenerative conditions, such as vascular dementia, that mask any benefits obtained by removing amyloid-β. It may be that amyloid-β accumulation is a side-effect of glial cell dysfunction, and it is glial cell dysfunction rather than amyloid-β accumulation that drives the condition from its early to later stages.

There has been a fair amount of discussion over the recent move of aducanumab back across the line of FDA approval, following an earlier declaration of failure. There is the usual skepticism regarding motivation on the part of the biotech companies involved. Yet this doesn't make much difference to the present situation with regard to amyloid-β clearance. Aducanumab is either a marginal therapy that just passes the minimum standards for regulatory approval, or a marginal therapy that doesn't. It is modestly slowing progression, not working miracles. Either way, clearance of amyloid-β on its own isn't enough, or it isn't the right point of intervention for this condition.

'Reports of My Death Are Greatly Exaggerated.' Signed, Aducanumab

On October 22, Biogen stunned the Alzheimer's field by announcing that aducanumab - presumed dead last March after failing a futility analysis - appears to have worked in one of its two Phase 3 trials, after all. Based on the results of a new analysis, and interactions with the FDA, Biogen will file for regulatory approval in early 2020. Why the revival? The interim futility analysis was flawed and did not adequately take into account the effect of two late protocol amendments that boosted the number of people receiving the highest dose of this biologic drug. A new analysis included three more months of data, as well as data from the participants who did not complete the full course of treatment. It showed that one of the two trials, called EMERGE, in fact met its primary and secondary endpoints. Oddly, the identical ENGAGE trial, which started one month earlier, was a tad larger, yet had slightly fewer people who took an uninterrupted course of the maximum dose, remained negative.

In each trial, about half the participants on aducanumab were randomly assigned to titrate up to a low dose of drug - 3 mg/kg for ApoE4 carriers, 6 mg/kg for noncarriers. This difference was because ApoE4 carriers are more susceptible to ARIA, the fluid retention in the brain that accompanies treatment with many amyloid-removing therapies. In the high-dose group, ApoE4 carriers initially titrated up to 6 mg/kg; noncarriers to 10 mg/kg. However, in March 2017, about 18 months into the trial, the protocol was amended to allow ApoE4 carriers to titrate up to 10 mg/kg, as well. This was based on accumulating data from several studies suggesting that ARIA is a manageable side effect that usually resolves without harm.

Analysis of the more recent, larger data set suggested that duration of treatment at the high dose was the key factor. In addition, interruption of treatment played a role. In EMERGE, participants on the low dose had a trend of declining more slowly than those on placebo on the primary outcome, the CDR Sum of Boxes, but this was well shy of statistical significance. Participants on the high dose declined 23 percent more slowly than those on placebo, with a significant p value of 0.01. Secondary endpoints were similar. The high-dose group declined about a quarter less on the ADAS-Cog13, a cognitive battery, and up to 46 percent more slowly on the ADCS Activities of Daily Living, a caregiver assessment.

Investigating the Mechanisms by which Klotho Increases Autophagy

Expression of the klotho gene declines with age, while approaches that increase levels of the klotho protein have been demonstrated to slow aging in mice. Some fraction of this outcome stems from increased activity of the cellular housekeeping processes of autophagy, responsible for recycling metabolic waste and damaged molecular machinery and cellular components. Many of the methods of modestly slowing aging in laboratory species are characterized by upregulated autophagy, and some, such as calorie restriction, require functional autophagy in order to slow aging.

In order to study autophagy, researchers have created a mouse model that has increased levels of autophagy. This is performed by mutating a component of what is called the beclin 1-BCL2 regulatory complex. When BCL2 binds beclin 1, autophagy is turned off. The engineered mutation in beclin 1 prevents BCL2 from binding, and allows beclin 1 to continue to promote the formation of the autophagosome, which results in continuously higher levels of autophagy in the mice.

The results of this study demonstrate that the mice with increased levels of autophagy have a significantly increased lifespan. Studies showed that not only do these beclin 1 mutant mice live longer, but also healthier, having better kidney and heart function as well as less spontaneous tumor formation. Additionally, their premature lethality and infertility is rescued. These results suggest that promoting autophagy in this manner can promote mammalian healthspan and lifespan and should be further studied.

The researchers then wondered if known anti-aging compounds could be producing their effects through a pathway similar to their genetic mouse model. Klotho, a membrane protein, was one such compound they examined. It has previously been shown that animals genetically engineered to be deficient in klotho have reduced lifespan and that administering klotho could extend lifespan. Additionally, it was observed that administering klotho promoted more autophagy. Researchers took klotho-deficient mice and observed a noticeable increase in beclin 1-BCL2 binding, leading to less autophagy. By taking these klotho deficient mice and mutating beclin 1 they were able to rescue the effects of klotho deficiency and return autophagy to normal. Furthermore, by administering klotho to human HeLa cells they were able to reduce beclin 1-BCL2 binding showing that this effect is not isolated to mice, but applicable to humans as well.

Link: https://www.buckinstitute.org/blog/the-title-is-cellular-housekeeping-how-autophagy-models-in-mice-could-lead-to-treatment-in-humans/

Deoxydihydroceramide is Required for Much of the Cell Death Following Hypoxia

Researchers here provide evidence to show that a single type of ceramide, deoxydihydroceramide, is responsible for the tissue death following deprivation of oxygen, hypoxia, such as occurs after a heart attack. Suppressing levels of this ceramide rapidly enough in response to the event can reduce the damage. This is one of a number of lines of research focused on attempting to preserve cells following transient hypoxia by sabotaging the mechanisms that lead to cell death.

Heart attack and stroke are the primary cause of death worldwide. When a blood clot forms, it blocks the blood vessel and blood circulation. The non-irrigated tissues no longer receive oxygen and rapidly undergo necrosis, from which they cannot recover. But what causes the necrosis under these conditions? Not all animals are so sensitive to the absence of oxygen, worms can live three days without oxygen, some turtles can live several months, and certain bacteria indefinitely.

The researchers saw that in worms a particular species of ceramide, deoxydihydroceramide, accumulated to dangerous levels under anoxia, that is when tissues were completely deprived of oxygen. Upon an infarct, the synthesis of deoxydihydroceramide increases and becomes toxic for cells. Using mass spectrometry, researchers observed that this ceramide blocks certain protein complexes and provokes defects in the cytoskeleton of cells and the proper function of mitochondria, causing tissue necrosis.

Based on these results, researchers injected an inhibitor of ceramide synthesis in mice just before a heart infarct. They found that the mice that received the injection have 30% less tissue necrosis when compared to control mice that received an injection without the inhibitor. The researchers are now working on an inhibitor that will target more specifically deoxydihydroceramide, which is likely to have fewer side effects and maintain the normal body functions of ceramides.

Link: https://www.unige.ch/communication/communiques/en/2019/les-dommages-lies-aux-infarctus-bientot-reduits-de-30/

Depletion of Microglia Greatly Reduces Tau Pathology in Mouse Models of Alzheimer's Disease

Today's research adds to the body of work supporting a vital role for microglia in the progression of Alzheimer's disease from early stages characterized by amyloid-β aggregation and mild cognitive impairment to later stages characterized by tau aggregation and severe neurodegeneration. Microglia are one of the classes of supporting immune cell in the brain. They are similar to macrophages of the innate immune system that are present in the rest of the body, outside the central nervous system, but microglia undertake a much more varied set of tasks beyond clearing up debris, hunting pathogens, and the usual portfolio of immune cell activities. Much of the maintenance and alteration of synaptic connections between neurons is dependent on the presence of microglia, for example.

It is becoming clear that inflammatory dysfunction in microglia is a part of the growing metabolic disarray that allows tau protein to aggregate in the brain, and thereby lead to the death of neurons. It is a matter for debate as to whether this occurs because of amyloid-β aggregation, or whether amyloid-β aggregation is just another consequence of microglial dysfunction that occurs for other underlying reasons.

Studies published earlier this year, carried out in animal models of Alzheimer's disease, suggest that cellular senescence of microglia is very influential in the progression of neurodegeneration. Some of the early senolytic drugs, such as dasatinib, can cross the blood-brain barrier, and so it is possible to test selective destruction of senescent cells in the brain as an approach to therapy. The results offer the possibility that presently available low-cost senolytics may turn out to be more effective than most present approaches to treatment of neurodegenerative conditions.

Microglia can be inflammatory without being senescent, however. Like macrophages, microglia can switch between modes of behavior, known as polarizations, with the two of greatest interest being M1, inflammatory and aggressive in pursuit of pathogens, and M2, anti-inflammatory and focused on regeneration and repair. Numerous studies have suggested that aging is characterized by excessive proportions of M1 macrophages and microglia, though exactly why this is the case - how it connects to rising levels of the underlying molecular damage of aging - remains an open question.

Targeting immune cells may be potential therapy for Alzheimer's

Under ordinary circumstances, tau contributes to the normal, healthy functioning of brain neurons. In some people, though, it collects into toxic tangles that are a hallmark of neurodegenerative diseases such as Alzheimer's. Researchers had shown that microglia limit the development of a harmful form of tau. But they also suspected that microglial cells could be a double-edged sword. Later in the course of the disease, once the tau tangles have formed, the cells' attempts to attack the tangles might harm nearby neurons and contribute to neurodegeneration.

To understand the role of microglial cells in tau-driven neurodegeneration, researchers first studied genetically modified mice that carry a mutant form of human tau that easily clumps together. Typically, such mice start developing tau tangles at around 6 months of age and exhibiting signs of neurological damage by 9 months. Then, the researchers turned their attention to the gene APOE. Everyone carries some version of APOE, but people who carry the APOE4 variant have up to 12 times the risk of developing Alzheimer's disease compared with those who carry lower-risk variants. The researchers genetically modified the mice to carry the human APOE4 variant or no APOE gene. APOE4 amplifies the toxic effects of tau on neurons.

For three months, starting when the mice were 6 months of age, the researchers fed some mice a compound to deplete microglia in their brains. Other mice were given a placebo for comparison. The brains of mice with tau tangles and the high-risk genetic variant were severely shrunken and damaged by 9 months of age - as long as microglia were also present. If microglia had been eliminated by the compound, the mice's brains looked essentially normal and healthy with less evidence of harmful forms of tau despite the presence of the risky form of APOE. Further, mice with microglia and mutant human tau but no APOE also had minimal brain damage and fewer signs of damaging tau tangles. Additional experiments showed that microglia need APOE to become activated. Microglia that have not been activated do not destroy brain tissue or promote the development of harmful forms of tau.

Microglia drive APOE-dependent neurodegeneration in a tauopathy mouse model

Chronic activation of brain innate immunity is a prominent feature of Alzheimer's disease (AD) and primary tauopathies. However, to what degree innate immunity contributes to neurodegeneration as compared with pathological protein-induced neurotoxicity, and the requirement of a particular glial cell type in neurodegeneration, are still unclear. Here we demonstrate that microglia-mediated damage, rather than pathological tau-induced direct neurotoxicity, is the leading force driving neurodegeneration in a tauopathy mouse model. Importantly, the progression of phosphorylated tau pathology is also driven by microglia.

In addition, we found that APOE, the strongest genetic risk factor for AD, regulates neurodegeneration predominantly by modulating microglial activation, although a minor role of apoE in regulating phosphorylated tau and insoluble tau formation independent of its immunomodulatory function was also identified. Our results suggest that therapeutic strategies targeting microglia may represent an effective approach to prevent disease progression in the setting of tauopathy.

Significant Differences in Memory Formation are Observed in Young Mice versus Old Mice

The brain is exceptionally complex, and thus the ways in which it changes in response to the damage and dysfunction of aging are also exceptionally complex. Memory is no exception, as illustrated here. This is one of the many reasons why the best hope for extending healthy life span significantly in the near future is to reverse the underlying damage, a comparatively simple set of processes, though not without its challenges. This should at the very least enable prevention of the deterioration and change of the aging brain, even if some of those downstream consequences of damage turn out to be irreversible via normal maintenance processes once the causative damage is repaired.

Long-lasting changes at synapses enable memory storage in the brain. Although aging is associated with impaired memory formation, it is not known whether the synaptic underpinnings of memory storage differ with age. Using a training schedule that results in the same behavioral memory formation in young and aged mice, we examined synapse ultrastructure and molecular signaling in the hippocampus after contextual fear conditioning.

Only in young, but not old mice, contextual fear memory formation was associated with synaptic changes that characterize well-known, long-term potentiation, a strengthening of existing synapses with one input. Instead, old-age memory was correlated with generation of multi-innervated dendritic spines (MISs), which are predominantly two-input synapses formed by the attraction of an additional excitatory, presynaptic terminal onto an existing synapse. Accordingly, a blocker used to inhibit MIS generation impaired contextual fear memory only in old mice.

Memory reconsolidation has been suggested to update memory storage. Reconsolidation involves initial destabilization followed by protein-synthesis-dependent restabilization. Destabilization can be analyzed when restabilization is blocked. To our knowledge, destabilization has only been studied at a young age. An earlier study suggested that reconsolidation is impaired in aged rats and humans. However, this study did not block protein synthesis to assess memory destabilization.

Here, we show that memory destabilization is impaired in aged mice. We detected this impairment using a re-exposure protocol that induces destabilization of strong contextual fear memory in young mice. Thus, in old age, memory destabilization may not only be impaired, it may be completely blocked. It is conceivable that impaired memory destabilization in aging is due to the involvement of MISs, as the reversal of these multi-input synapses into one-input synapses might not be induced by retrieval. An MIS-based memory-storing mechanism may explain why memory updating, a fundamental cognitive process, is impaired in old age.

Link: https://doi.org/10.1016/j.cub.2019.08.064

Libella Gene Thereapeutics Moving Ahead with a Small Phase 1 Trial of Telomerase Gene Therapy

Libella Gene Therapeutics is developing telomerase gene therapy as a clinical treatment, work that results from more than a decade of studies in mice that show extended life, reduced cancer risk, and improved health. Telomerase acts to lengthen telomeres, the repeated DNA sequences at the ends of chromosomes that shorten with each cell division. Average telomere length in the somatic cells making up any given tissue is a function of the rate of cell division versus the pace at which stem cells produce new daughter somatic cells with long telomeres. Since stem cell activity declines with age, it is no surprise to see telomere length shorten.

Telomerase gene therapy acts in part by extending the working life of somatic cells, and thus the prospect of active cells, burdened with damage due to a longer working life, and the attendant cancer risk has always been a concern. That telomerase gene therapy reduces cancer incidence in mice may be the result of improvements in immune function, particularly cancer immunosurveillance, that outweigh any increase in cancer risk due to increased activity of damaged cells. Mice and humans have very different telomere dynamics, however, so it remains to be seen whether or not the same balance of outcomes is the case in our species. The best way to find out, as ever, is for brave volunteers to try the therapy.

The clinical trial (NCT04133649) has just began recruitment stage. The procedure will consist of a single intravenous injection, followed by six safety and efficacy evaluations. Participants will receive adeno-associated virus (AAV) containing gene expressing telomerase reverse transcriptase enzyme. AAV is expected to move from the circulatory system to tissues, invade cells, and establish telomerase expression inside cells. Viruses will not modify the genome - AAV's genetic material normally exists separately in the cell cytoplasm (as an episome).

Formally, the study is phase I trial, which limits the main goal - whether it is successful or failed attempt - to safety only. In this case, the primary goal was declared as the incidence of adverse effects. Determination of dosing and tolerability is an important first step in all gene therapies. High doses of viral particles result in significant immunological reaction. Moreover, liver damage is a common adverse effect in early gene therapies, because of liver's participation in blood filtering. In addition, telomerase introduces additional risk on its own. In 85% cases of cancers, telomerase is found upregulated, which raises concerns about potential oncogenicity of AAVs with hTERT gene.

The trial is accompanied by two similar phase I attempts (NCT04133454, NCT04110964), which target Alzheimer's disease and critical limb ischemia. Patients participating in the trial will be enrolled in their country of origin and will travel to Colombia. Patients will stay in Colombia for a few days while the treatment is administered and hospitalized for observation. Patients will then return to their country of origin and will be followed-up per the study protocol.

Link: https://genomecontext.com/anti-aging-clinical-trial-will-test-genetic-introduction-of-telomerase/

A Mouse Lineage with Very Long Telomeres Exhibits Longer Life Span

Researchers here report on the generation of a mouse lineage with much longer telomeres than is normally the case. Telomeres are the caps of repeated DNA sequences at the ends of chromosomes; a little is lost with each cell division, and cells self-destruct or become senescent when telomeres become too short. This acts as a limit on the ability to replicate for most cells in the body. Stem cells use telomerase to maintain long telomeres, however, allowing them an indefinite number of cell divisions, used to deliver daughter somatic cells with long telomeres into tissues. Thus average telomere length in a tissue is some function of the pace of cell division and the pace at which stem cells generate replacement cells.

This division of cells into a privileged minority and a restricted majority is the way in which all higher forms of animal life control the risk of mutation and the unfettered replication of cancer to a sufficient degree to allow evolutionary success. Over the past decade or more, researchers have been exploring ways to alter the balance of telomere length and telomerase activity in mice, and have found that enhanced telomerase activity extends life, reduces cancer risk, and improves health. As a consequence a number of groups are working on delivery of telomerase gene therapies to human patients, though there remains the question of whether the balance of cancer risk is the same in humans as in mice. The two species have quite radically different telomere dynamics.

In this study, the enhanced mice live somewhat longer than their unmodified peers, though not as much longer as is the case for the application of telomerase gene therapy. The mice do also exhibit reduced cancer risk, however. The scientists here class telomere shortening as a cause of aging, which is not a point universally agreed upon. Reductions in average telomere length in tissues looks much more like a downstream consequence of reduced stem cell activity than an independent mechanism.

Researchers obtain the first mice born with hyper-long telomeres and show that it is possible to extend life without any genetic modification

Given the relationship between telomeres and ageing - telomeres shorten throughout life, so older organisms have shorter telomeres - scientists launched a study generating mice in which 100% of their cells had hyper-long telomeres. The findings show only positive consequences: the animals with hyper-long telomeres live longer in better health, free from cancer and obesity. "This finding supports the idea that, when it comes to determining longevity, genes are not the only thing to consider. There is margin for extending life without altering the genes".

Telomeres form the end of chromosomes, in the nucleus of each cell in the body. Their function is to protect the integrity of the genetic information in DNA. Whenever the cells divide the telomeres, they are shortened a little, so one of the main characteristics of ageing is the accumulation of short telomeres in cells. Up to now, all interventions on the length of telomeres have been based on altering the expression of genes, through one technique or another. In fact, researchers developed a gene therapy that fosters the synthesis of telomerase, obtaining mice that live 24% longer without developing cancer of other illnesses associated with age.

In 2009, researchers worked with the so-called induced pluripotent stem cells - cells from an adult organism which have been given back pluripotency or the capacity to generate a full organism - and they observed that after a certain number of divisions in culture plates, these cells acquired telomeres twice as long as normal. Intrigued, they confirmed that the same occurred in normal embryonic cells - also pluripotent - as they are kept in cultivation after being removed from the blastocyst. The team found that during the pluripotency stage, there are certain epigenetic marks on the telomeric chromatin that facilitate their lengthening by the telomerase enzyme. For this reason, the telomeres of pluripotency cells in cultivation were extended to twice the normal length.

The question was whether the embryonic cells with hyper-long telomeres could produce live mice? Some years ago, the group demonstrated that they could, and have now managed to obtain mice with hyper-long telomeres in 100% of their cells. The mice are slimmer than normal because they accumulate less fat. They also show lower metabolic ageing, with lower levels of cholesterol and LDL, and an increased tolerance to insulin and glucose. Damage to their DNA as they age is less and their mitochondria, another Achilles heel of ageing, function better. The average longevity of mice with hyper-long telomeres is 13% higher than usual. The metabolic alterations observed are also relevant as this is the first time that a clear relationship between the length of telomeres and metabolism has been found. The genetic route of insulin and glucose metabolism is identified as one of the most important in relation to ageing.

Mice with hyper-long telomeres show less metabolic aging and longer lifespans

Short telomeres trigger age-related pathologies and shorter lifespans in mice and humans. In the past, we generated mouse embryonic (ES) cells with longer telomeres than normal (hyper-long telomeres) in the absence of genetic manipulations, which contributed to all mouse tissues. To address whether hyper-long telomeres have deleterious effects, we generated mice in which 100% of their cells are derived from hyper-long telomere ES cells. We observe that these mice have longer telomeres and less DNA damage with aging. Hyper-long telomere mice are lean and show low cholesterol and LDL levels, as well as improved glucose and insulin tolerance. Hyper-long telomere mice also have less incidence of cancer and an increased longevity. These findings demonstrate that longer telomeres than normal in a given species are not deleterious but instead, show beneficial effects.

REST Regulates Neural Activity and Influences Life Span

Researchers here report their findings on the activity of the REST gene, which both regulates neural activity and appears to influence life span, likely through indirect effects on the well-studied processes of insulin signaling. As such, this is interesting for the connection to neural activity, but otherwise irrelevant to the future of developing means to lengthen human life span. Effect sizes related to insulin signaling are much larger in short-lived lower species than they are in long-lived higher species, and they are in any case only a way to modestly slow aging, not a road to rejuvenation.

Researchers began their investigation by analyzing gene expression patterns in donated brain tissue from hundreds of people who died at ages ranging from 60 to over 100. The information had been collected through three separate research studies of older adults. Those analyzed in the current study were cognitively intact, meaning they had no dementia. Immediately, a striking difference appeared between the older and younger study participants: The longest-lived people - those over 85 - had lower expression of genes related to neural excitation than those who died between the ages of 60 and 80.

Next came the question that all scientists confront: correlation or causation? The team conducted a barrage of experiments, including genetic, cell and molecular biology tests in the model organism Caenorhabditis elegans; analyses of genetically altered mice; and additional brain tissue analyses of people who lived for more than a century.

These experiments revealed that altering neural excitation does indeed affect life span-and illuminated what might be happening on a molecular level. All signs pointed to the protein REST. REST, which is known to regulate genes, also suppresses neural excitation, the researchers found. Blocking REST or its equivalent in the animal models led to higher neural activity and earlier deaths, while boosting REST did the opposite. And human centenarians had significantly more REST in the nuclei of their brain cells than people who died in their 70s or 80s.

The researchers found that from worms to mammals, REST suppresses the expression of genes that are centrally involved in neural excitation, such as ion channels, neurotransmitter receptors and structural components of synapses. Lower excitation in turn activates a family of proteins known as forkhead transcription factors. These proteins have been shown to mediate a "longevity pathway" via insulin/IGF signaling in many animals. It's the same pathway that scientists believe can be activated by caloric restriction.

Link: https://hms.harvard.edu/news/new-player-human-aging

Processing Epidemiological Data to Show that Obesity and High Blood Pressure Cause Shorter Life Spans

Researchers here demonstrate an approach that can be used with large human epidemiological databases to demonstrate that, as expected, both greater amounts of visceral fat tissue and raised blood pressure cause reductions in life span. The underlying mechanisms have been explored at length by the research community. Visceral fat tissue produces chronic inflammation through a variety of mechanisms, including a raised burden of cellular senescence, while raised blood pressure produces damage to fragile tissues in the brain, kidney, and other organs, and accelerates the progression of atherosclerosis.

Researchers are exploring the cause and effect relationships between common health indicators and lifespan, by analyzing polygenic risk scores (PRS), a numerical score of a person's risk for disease based on multiple genetic variants. To find a clinically actionable indicator of genetic risk, researchers started by examining samples from BioBank Japan, which has a heavy East Asian representation. They used the genetic data of 180,000 people to perform genome-wide association studies for 45 common health indicators. By analyzing the PRS of each indicator, they identified the ones that most strongly affected lifespan.

"If you only look at raw clinical data associated to lifespan, you cannot show which attribute is cause and which is effect. For instance, when a patient is dying, their blood pressure is low, so you can't necessarily know if blood pressure is the cause of their death. By using PRS, we can get closer to identifying the cause, because PRS is less susceptible to the acquired confounding factors such as decline in general health."

For the individuals in BioBank Japan, researchers found that high blood pressure and obesity had the most significant associations to reduced lifespan. To improve the diversity of their study and ensure that these associations held across populations, the researchers collaborated with the UK Biobank and FinnGen, and performed a trans-ethnic association study of PRS and lifespan. This increased the sample size to 700,000 and, with the help of additional analyses, reinforced the conclusion that blood pressure and obesity are causally related to reduced lifespan.

Link: https://www.ashg.org/press/201910-prs-bp.shtml

Aubrey de Grey on the TAME Metformin Trial

As you may or may not have heard, the TAME metformin trial recently received the remaining $40 million in philanthropic funding that is needed to progress. The trial will cost $75 million in total, and to my eyes this is quite the waste of funding. Aubrey de Grey of the SENS Research Foundation is far more polite on this topic in today's editorial, which isn't too surprising given our respective views on regulation.

I'll set aside for the moment the point that metformin is a weak treatment with a small effect size on life span, unreliable animal data, life span data in humans arising from a single trial for diabetics rather than healthy individuals, and side effects that are significant in comparison to the small effect size. The point of the TAME exercise is convince the FDA to accept aging as an indication - or something close enough that people can work with it. That never needed a trial to exist in order to take place. The important work has been a process of Nir Barzilai, his collaborators, and fellow travelers such as the Longevity Dividend folk negotiating with FDA bureaucrats, against a backdrop of increasing patient advocacy and activism for aging to be classified as a legitimate target for therapy.

Further, this labor of filling in a ditch dug by the FDA isn't even needed. The same end could be just as well achieved by putting rejuvenation therapies through the FDA process for any relevant age-related indication, and then engaging in a running battle over the off-label use that will come to be the overwhelming majority of all use for these treatments. That is exactly what will soon happen for the dasatinib and quercetin combination, as the world wakes up to just how large and reliable the benefits are for patients undergoing this sort of first generation senolytic therapy. The way forward will be established for these very cheap, revolutionary therapies, and then can be followed by everyone else developing a rejuvenation therapy. Under this sort of pressure, the FDA will change because they have to.

Since the TAME trial is forging ahead, we can hope that the philanthropists involved may choose to do the same for senolytic therapies - which would have been a far better choice, had the required information been widely available back in 2015, when the TAME trial originated. Nonetheless, it remains the case that there are far, far, far better uses for $75 million in this field.

TAME: a genuinely good use of 75 million dollars

The TAME trial is an attempt to determine whether metformin, the well-known anti-diabetes drug, actually has much more wide-ranging benefits against the health problems of late life - so wide-ranging, in fact, that they could uncontroversially be described as addressing aging itself. But then, hang on, metformin is an old drug. I mean, a really old drug - it has been off patent since forever. There is no way in hell to make money out of it. So, how would we fund a clinical trial of it? Well, yes: the only way is philanthropic. This will only happen if there are people out there who are sufficiently convinced of the importance of such a trial that they will pony up the requisite capital even though doing so is completely bereft of financial upside.

But the logic is persuasive in another way: precisely because metformin is such an old drug, a trial can immediately focus on efficacy, in contrast to the need for stringent tests of safety to come first in the case of a new drug. And, sure enough, pretty much as soon as the idea of such a trial was formulated, nearly half of the required $75M was pledged by the long-standing supporter of gerontology research, Paul Glenn, via (as has long been his custom) the American Federation for Aging Research (AFAR). At that point, however, the pursuit of funds stalled for a couple of years - in particular, the National Institute on Aging twice rejected applications for the remaining money - but, as noted above, the remaining support materialised very recently, courtesy of an anonymous donor.

A question remains, however: is this, in fact, the best use of $75M in the crusade against aging? Well, that's a few times the total amount that SENS Research Foundation has raised in its entire history, so it will not surprise you that I cannot quite look you in the eye and answer that question in the affirmative. But it is certainly not a waste of money either: indeed, I do feel able to declare that it is a pretty good use.

First, I think there is a reasonable chance that the trial will succeed, albeit modestly. There's no way that a brief course of metformin will give people a decade of extra life, but all that's really needed here is a statistically significant improvement versus controls, and with that kind of money the study can be powered well enough to achieve that threshold. The other rationale for this trial is arguably even greater. It is that the description of the trial incorporates a de facto definitition of aging as the clinical endpoint, which has been more-or-less approved by the FDA, and which can thus be copied and pasted into any future trial for an intervention against aging. That endpoint was the result of a highly arduous negotiation with the FDA that was led by the inestimable Nir Barzilai.

Treating Periodontitis Reduces Inflammatory Markers and Blood Pressure in Hypertensive Patients

Researchers here provide evidence for periodontitis, gum disease, to contribute to hypertension, chronic raised blood pressure, via inflammatory mechanisms. Aggressively treating the periodontitis in hypertensive patients reduces both blood pressure and inflammatory markers. Periodontitis has previously been linked with a modestly increased risk of dementia, as well as increased cardiovascular mortality risk. In both cases, increased inflammation is strongly suspected to be the linking mechanism.

Experimental and observational clinical evidence suggests a prominent role of inflammation in the development of hypertension. In particular, activation of immune cells has been demonstrated in hypertension. Hypertension is more prevalent in patients with immune-mediated disorders, such as psoriasis, rheumatoid arthritis or systemic lupus erythematosus. Thus, chronic inflammatory disorders, could provide a substrate for the pro-hypertensive inflammation.

Periodontitis is one of the most common inflammatory conditions worldwide, representing the sixth most prevalent condition worldwide with prevalence of 20-50%. It is linked to cardiovascular inflammation and endothelial dysfunction. Therefore, if causally associated, periodontitis could significantly contribute to the global hypertensive burden and interventions targeting oral inflammation would have an important role in the prevention of hypertension and its complications. Observational evidence suggests that moderate-severe periodontitis is associated with increased odds for hypertension.

Because of this, it is imperative to establish if periodontitis can cause hypertension. Our group has recently shown that immune activation induced by a keystone periodontal pathogen (Porphyromonas gingivalis) promotes the development of hypertension in mice. Small interventional studies concluded that intensive periodontal therapy may lead to blood pressure reduction, although sufficiently powered evidence in well-defined hypertensive cohorts is lacking. We thus performed a randomized intervention trial on the effects of treatment of periodontitis on blood pressure. One hundred and one hypertensive patients with moderate to severe periodontitis were randomized to intensive periodontal treatment (IPT) or control periodontal treatment (CPT) with systolic blood pressure (SBP) as the primary outcome.

Intensive periodontal treatment improved periodontal status at 2 months, compared to CPT. This was accompanied by a substantial reduction in mean SBP in IPT compared to the CPT (mean difference of -11.1 mmHg). Systolic BP reduction was correlated to periodontal status improvement. Diastolic blood pressure and endothelial function (flow-mediated dilation) were also improved by IPT. These cardiovascular changes were accompanied by reductions in circulating IFN-γ and IL-6 as well as activated and immunosenescent CD8+ T cells, previously implicated in hypertension.

Link: https://doi.org/10.1093/eurheartj/ehz646

Cardiac Glycosides, a Category that Includes Several Approved Drugs, are Found to be Senolytic

Researchers here report on the discovery that the class of drugs known as cardiac glycosides are senolytic, capable of selectively destroying the lingering senescent cells that contribute to aging and age-related disease. These cardiac glycosides are not a good candidate for use by the self-experimentation community, however, despite the existence of low-cost generic drugs in this category. They are unpleasant compounds, quite toxic, and when used in medicine come attached to a long list of side effects that sound well worth avoiding. It may nonetheless be the case that new senolytic drugs will be developed from these starting points, given the present enthusiasm for this line of work, by building upon the mechanisms to find less toxic small molecules that have the desired interactions with cellular biochemistry.

Senescence is a cellular stress response that results in the stable growth arrest of old and damaged cells. The past decade has revealed that senescent cells play important roles in a growing list of diseases from cancer, to arthritis, atherosclerosis, and many more. Previous studies have shown that the specific elimination of senescent cells with drugs or using genetic tricks makes mice live healthier for longer. Eliminating senescent cells results in improvements in fibrosis, cataracts, atherosclerosis and in more than 20 other diseases.

After examining a library of drugs that are already used in the clinic and testing them on normal and senescent cells, the researchers identified ouabain as a potential candidate to selectively kill senescent cells. Ouabain belongs to a family of natural compounds called cardiac glycosides that include also digoxin and digitoxin. Cardiac glycosides are used in the clinic to treat cardiac arrythmias and atrial fibrillation. In this study it was found that cardiac glycosides selectively eliminate many types of senescent cells, including when senescence has been triggered by irradiation, cancer itself, or chemotherapeutic drugs - such as etoposide or doxorubicin. The fact that ouabain can eliminate different types of senescent cells emphasises its potential as a broad spectrum senolytic.

"These drugs are already used in the clinic, so they could be repurposed to treat a long list of diseases including cancer. This is something we are keen to explore with our clinical collaborators. Moreover, many patients are being treated with digoxin and an epidemiologist could look retrospectively and ask the question of whether those patients who were treated with digoxin are doing better than those who weren't."

Link: https://lms.mrc.ac.uk/repurposing-heart-drugs-to-target-cancer-cells/

Help the SENS MitoMouse Rejuvenation Research Project Hit Its Crowdfunding Stretch Goals

The latest crowdfunded research project undertaken by the SENS Research Foundation involves using the genetically engineered maximally modifiable mouse lineage in order to demonstrate the ability to copy a version of the ATP8 mitochondrial gene into the cell nucleus, a process known as allotopic expression, and thus prevent mutational damage to this gene from degrading mitochondrial function. This is a modest step on the road towards bringing this class of genetic engineering project to the point of readiness for commercial development, when a biotech startup company could be created to carry it forward.

In just a few weeks of crowdfunding, the project has already hit the initial funding goal of $50,000. There are still stretch goals to reach, however - so if you want to see more work on preventing the mitochondrial contribution to aging, then join in and help.

Mitochondria are the power plants of the cell, every cell containing a herd of these organelles, descendants of ancient symbiotic bacteria. They bear a remnant of the original bacterial DNA, and that is where the problems start. This DNA encodes thirteen proteins vital to the operation of mitochondria. Unfortunately, this genome is poorly protected, poorly repaired, and vulnerable to the oxidative molecules generated by mitochondria as a side-effect of their duties in the cell. Some forms of damage, such as major deletions, can cause mitochondria to become both dysfunctional and more competitive, in replication and resistance to quality control mechanisms, than their undamaged peers. The cell is quickly taken over by broken mitochondria, and becomes broken itself, exporting oxidative molecules into the surrounding tissue. This contributes to the aging process.

If, however, copies of these mitochondrial genes are placed into the cell nucleus, then DNA damage in the mitochondria will not affect their function. The necessary proteins will still be manufactured, delivered, and used. This has been demonstrated for the ND4 gene in recent years, that development program conducted by Gensight Biologics, and the SENS Research Foundation team have achieved allotopic expression of ATP6 and ATP8 in cell studies. More and faster progress is needed, however, to move this work into animal models, and then towards human studies.

The MitoMouse Project Smashes its Initial Fundraising Goal!

Wonderful news, the MitoMouse project has successfully reached its initial $50,000 goal and is well on the way towards the first stretch goal! This now means the project will launch at the lab and the MitoMouse strain will be created. The next step for this ambitious project is to actually create progeny from the SickMice and MitoMice in order to have an effective model to test the mitochondrial repair approach, which has already been shown to work in cells, in living animals. If successful it would be vindication for mitochondrial repair therapy and move the therapy closer to translation to humans.

MitoMouse: SENS Transgenic Mouse Project

Mice of the C57/BL6MT-FVB strain (let's call them "SickMice") have a mitochondrial gene defect (a mutation in the mitochondrial ATP8 gene) and exhibit several age-related symptoms including lower fertility, arthritis, type II diabetes, and neurological impairments. Since mitochondria are only inherited from the mother, cross-breeding female SickMice with male mice from other models will result in the same mitochondrial dysfunction.

We will use the maximally modifiable model to create a new transgenic mouse (the "allotopic ATP8 transgenic mouse - Mitomouse"). This mouse will have the ATP8 gene that is important for mitochondrial function 'hidden' in the cell nucleus and thus capable of being passed on to offspring irrespective of gender.

Our hypothesis is that both male and female offspring from SickMice crossed with MitoMice will result in rescued mitochondrial function. This would prove the viability of the MitoSENS strategy by showing that functional backup copies of mitochondrial DNA genes in the nucleus can replace their mutated counterparts in live animals.

TET2 Regulates the Neuroinflammatory Response in Microglia

TET2 upregulation has been shown to improve neurogenesis and cognitive function in old mice. So it is interesting that researchers here link increased expression of TET2 with the inflammatory response of microglia in the brain. The broader context is that is becoming increasingly clear that dysfunctional and inflammatory microglia contribute significantly to the progression of neurodegenerative conditions. This is one of many examples of apparently contradictory results to illustrate the point that cellular biochemistry is very complex. Contradictions usually indicate that there is much left to be understood about the way in which the systems studied fit together in practice.

Microglia, the resident immune cells in the central nervous system, are key players in maintaining homeostasis in the brain. Microglia play a wide variety of roles under physiological and pathological conditions. In the healthy brain, microglia are responsible for neuronal activity-dependent synapse pruning during postnatal development. Upon neuronal injury or infection, microglia become rapid responders that initiate an innate inflammatory response. If the inflammatory response is exaggerated or chronic, it becomes detrimental for the surrounding neuronal population, as in Parkinson's disease and Alzheimer's disease.

Epigenomic mechanisms regulate distinct aspects of the inflammatory response in immune cells. Despite the central role for microglia in neuroinflammation and neurodegeneration, little is known about their epigenomic regulation of the inflammatory response. Here, we show that Ten-eleven translocation 2 (TET2) methylcytosine dioxygenase expression is increased in microglia upon stimulation with various inflammogens through a NF-κB-dependent pathway.

We found that TET2 regulates early gene transcriptional changes, leading to early metabolic alterations, as well as a later inflammatory response independently of its enzymatic activity. We further show that TET2 regulates the proinflammatory response in microglia of mice intraperitoneally injected with lipopolysaccharide. We observed that microglia associated with amyloid β plaques expressed TET2 in brain tissue from individuals with Alzheimer's disease and in 5xFAD mice. Collectively, our findings show that TET2 plays an important role in the microglial inflammatory response and suggest TET2 as a potential target to combat neurodegenerative brain disorders.

Link: https://doi.org/10.1016/j.celrep.2019.09.013

The Role of Adipogenic Progenitor Cells in Muscle Stem Cell Aging

The stem cells responsible for maintaining muscle tissue decline in function with age, becoming ever less active. This loss of function contributes to sarcopenia, the characteristic decline in muscle mass and strength that takes place with advancing age. Researchers here report on investigations of the role of adipogenic progenitor cells in the decline of muscle stem cell function. These progenitor cells are a necessary part of the muscle stem cell niche, but their behavior changes for the worse with advancing age, disrupting the balance of intracellular signaling needed for stem cell function.

Declining stem cell function during aging leads to impaired tissue function and contributes to delayed tissue repair following damage. In adult skeletal muscle, loss of myofiber integrity caused by mechanical injuries or diseases are repaired by resident muscle stem cells (MuSCs), called satellite cells, which promptly exit from quiescence after disruption of muscle architecture to expand, differentiate, and drive tissue regeneration. The fate of MuSCs fundamentally depends on the "niche", their local environment, which is orchestrated by diverse cellular and acellular elements.

Fibro/adipogenic progenitors (FAPs) constitute a population of interstitial mesenchymal cells in skeletal muscle which are devoid of myogenic potential, but support muscle stem cell commitment and can differentiate to the adipogenic or fibrotic lineages. A recent study demonstrated an important function of FAPs in maintaining long-term homeostasis of skeletal muscle: long term in-vivo depletion of FAPs decreased the number of MuSCs and reduced muscle mass and strength, suggesting a critical role of FAPs in maintaining the stem cell pool and sustaining myofiber growth and turnover.

The decline of MuSC function and muscle regenerative capacity during aging is under the control of a wide range of signals, out of which many arise from extrinsic cues coming from the local or systemic environment. A recent study investigated how aging influences the fate of FAPs and their cross-talk with MuSCs to regulate the balance between myogenesis, adipogenesis and fibrosis in skeletal muscle. Aging causes a clonal selection of FAPs, which favors their fibrogenic over adipogenic conversion. Interestingly, aged FAPs fail to efficiently amplify following muscle injury and aging alters the capacity of FAPs to support MuSC amplification and commitment. Both in-vitro co-culture and in-vivo transplantation of young FAPs rejuvenate aged MuSC function, but aged FAPs lose the ability to efficiently support MuSCs. The fact that the support of FAPs to MuSCs is communicable via conditioned medium suggested that soluble factors regulate this paracrine cross-talk.

Future research will be necessary to further dissect FAP function during homeostasis and tissue repair and unravel how the heterogeneity of this population is orchestrated in health and disease. In particular, the signals that mediate FAP dysfunction and the spatio-temporal control of their fate and interactions with MuSCs will be key to understand how aging of different compartments of the stem cell niche contribute to global regenerative capacity.

Link: https://doi.org/10.18632/aging.102304

We Still Have a Long Way to Go in Telling the World that the Longevity Industry Exists

I have been slacking on conference reports these past few months, but largely because the conferences I was attending were not wholly dedicated to longevity science or the longevity industry. I was at BASEL Life in Switzerland, where Alex Zhavoronkov and the In Silico Medicine crew had taken over a section of the broader conference to talk about aging, at the Founders Forum events in New York and Boston, where one will find a handful of influential people from outside our community who are interested in longevity, and LSX USA, a Boston biotech industry gathering. This week I was attending Giant Health in London, where the Aikora Health principals and Liz Parrish of BioViva Science organized a longevity-focused gathering within the much larger event.

Once one steps out of the circle of events dedicated to our community, such as Undoing Aging, Ending Age-Related Diseases, Longevity Therapeutics, and so forth, it is quite striking to see just how much more work there is left to do in terms of telling people that we exist. That there is a rejuvenation research community, that there are a few score startup biotech companies developing ways to treat aging, that the first rejuvenation therapies already exist in the form of senolytics, and they are pretty impressive so far in comparison to all other past approaches to age-related disease.

At BASEL Life, most of the people I talked to were scientists from diverse areas in the life sciences, and they had no real idea that upheaval was underway in the treatment of aging. At Founders Forum in Boston I moderated a panel of folk from the longevity industry (Doug Ethell of Leucadia Therapeutics, David Gobel of the Methuselah Foundation, Carolina Reis of OneSkin Technologies, and James Clement of Betterhumans), to talk about why matters are proceeding more slowly than we'd all like. The information that there was a longevity industry, that this was a thing that actually existed, was news to nearly everyone in the room. At LSX USA, also in Boston, I talked to a number of broader biotech industry CEOs and venture partners who were similarly politely interested to find out that rejuvenation therapies exist, are under development, and there is about to be a great up-ending of business as usual in the treatment of aging.

For that last crowd, I think the point is that nothing really exists to their eyes until there are a few companies with approved therapies. The longevity industry is still in phase I trials, more or less. Repurposing of existing drugs for longevity, such as dasatinib (potentially very beneficial) and metformin (definitely not) isn't on the radar of venture funds. Similarly for the possibility that some supplements or plant extracts are meaningfully senolytic, such as fisetin or piperlongumine. This is all inside baseball to the mainstream biotech industry until phase III trials have happened and at least a few companies with FDA approved drugs are trading on the stock exchanges. Or at least until the principals of some Big Pharma entity decide they want a seat at the longevity industry table and start buying companies with phase I or phase II successes.

People like Kelsey Moody of Ichor Therapeutics and Jim Mellon of Juvenescence quite explicitly see this as the big next step in the development of this industry. Currently the bulk of the biotech industry, however you want to characterize it, as Big Pharma, as major established venture funds, and so forth, doesn't know and doesn't care about the longevity industry. Part of the point of building a new industry of startup biotech companies is to change this fact. In the bigger picture, we are not doing this to produce a handful of therapies, though they will certainly be helpful, but rather to convince the broader industry in the only way it can be convinced, by succeeding in the production of therapies that have meaningful results in aging and age-related disease. Do this, and the floodgates of funding and resources will truly open.

A Brief History of Oisin Biotechnologies

This article includes a brief history of how the senolytic suicide gene therapy company Oisin Biotechnologies came about. Oisin Biotechnologies was one of the first senolytics biotech startups, of which there are now many, one of the first longevity industry companies, and launched at a time in which it was still quite hard to persuade investors that treating aging as a medical condition was a legitimate line of work. That was actually just a few years ago now, 2015 as seen in the rear view mirror, and matters have changed rapidly since then. At the present time there are perhaps 50 to 100 startup biotech companies that we might categorize as being in the longevity industry, and there is enough interest from investors for it to be comparatively easy to raise funds for any credible approach. Still, this is only the very first stage of what will grow to be a truly massive industry in the years ahead.

Matthew Scholz is co-founder and CEO of Oisín Biotechnologies. When asked what led him to focus on aging, Scholz responds, "Aging has been on my mind for a long time. Even at Immusoft, my long-term goal for the platform was to recreate the biochemical environment of youth in old age. I reasoned that it would never be possible to take enough drugs to accomplish this but, if you can program the body, you can do anything."

It wasn't until a chance meeting at a Health Extension Salon sponsored by Joe Betts-LaCroix in 2012, however, that Oisín Biotechnologies was first conceived. Judy Campisi took the stage to present her work at the Buck Institute for Research on Aging and the results of a recent mouse study. She explained how researchers had created transgenic mice in which senescent cells could be easily cleared with an otherwise innocuous drug. Scholz thought the results were amazing but didn't think it was a feasible approach from a clinical perspective. He leaned over to the guy sitting next to him - Gary Hudson - and said, "That's amazing, but I would do it totally differently."

That comment led to drinks at the bar, where Scholz explained to Hudson his strategy. And that conversation led to a collaboration that would become Oisín Biotechnologies. Gary Hudson not only liked what Scholz had to say, he also knew Dave Gobel at the Methuselah Foundation. And Gobel and the Methuselah Foundation were eager to fund Scholz's proof of principle.

Link: https://medium.com/methuselah-foundation/methuselah-ois%C3%ADn-and-the-zombie-apocalypse-804f2915bcae

CDK5 as a Target to Reduce Cell Death Following Ischemic Stroke

A great deal of effort goes towards methods of reducing the damage caused by ischemic stroke, the cell death in the brain that occurs in response to even a temporary loss of blood supply. Altering cellular reactions to this ischemia can greatly reduce this cell death response, and a number of different approaches to this goal have been demonstrated in mice over the years. Progress towards the clinic is, as ever, slow and uncertain, however. Ultimately what should be developed are not ways to make a stroke less traumatic, or to improve the presently all too limited degree to which recovery can take place, but rather the means to prevent stroke from occurring at all - therapies that aid in maintenance and periodic repair of the vascular system, preventing it from degenerating into a state in which stroke is possible.

Ischemic stroke is a devastating and major cause of morbidity and mortality worldwide. However, due to the narrow time window of thrombolytic therapy, new pharmacological therapeutic approaches are still necessary. Cyclin-dependent kinase 5 (CDK5) is a proline-directed serine/threonine kinase that interacts with NR2B and phosphorylates NR2B to promote ischemic neuronal death. Targeting aberrant CDK5 is neuroprotective for the neuronal loss, tauopathy, and microglial hyperreactivity induced by stroke.

Previously, a membrane-permeant targeting peptide-based method that rapidly and reversibly knocks down endogenous proteins through chaperone-mediated autophagy (CMA) had been validated. In this study, we synthesized a membrane-permeable peptide (Tat-CDK5-CTM) that specifically disrupts the binding of CDK5 and NR2B and then leads to the degradation of CDK5 by a lysosome-mediated pathway.

We found that the administration of Tat-CDK5-CTM not only retards calcium overload and neuronal death in oxygen and glucose deprivation (OGD)-treated neurons but also reduced the infarction area and neuronal loss and improved the neurological functions in MCAO (middle cerebral artery occlusion) mice. The peptide-directed lysosomal degradation of CDK5 is a promising therapeutic intervention for stroke.

Link: https://doi.org/10.14336/AD.2018.1225

Autoimmunity Against AT1 Receptor Spurs Endothelial Cellular Senescence and Vascular Aging

The presence of antibodies against the angiotensin II receptor (AT1 receptor) has been noted in a number of conditions involving raised blood pressure, from preeclampsia during pregnancy to the hypertension associated with aging. These antibodies induce dysfunction in vascular smooth muscle, preventing appropriate contraction and dilation in response to circumstances. That in and of itself is enough to produce hypertension, chronically raised blood pressure. In turn, that raised blood pressure causes damage to delicate tissues throughout the body, such as those of the kidney and the brain. It is an important aspect of aging, a way in which low-level molecular damage and disarray localized to blood vessels is converted to structural damage and progressive organ failure throughout the body.

In this context, the novel aspect of today's open access paper is the evidence for AT1 receptor antibodies to induce cellular senescence in vascular tissue, not that it also causes signs of vascular aging. From the research of recent years, it is clear that the accumulation of lingering senescent cells contributes to cardiovascular aging in a number of different ways, such as smooth muscle dysfunction, calcification of soft tissues, and foam cell behavior in atherosclerosis. There are a number of other conditions unrelated to aging in which excessive numbers of senescent cells play a role, such as type 1 diabetes. So it should perhaps not be unexpected at this point to find that additional conditions, such as preeclampsia, may be mediated in large part by cellular senescence.

The accumulation of senescent cells is, of course, a cause of aging. This point is now widely accepted in the research community, and senescent cells are the subject of growing research and development efforts largely focused on the production of senolytic therapies capable of safely and selectively destroying these errant cells in aged tissues. Senescent cells cause harm via a potent mix of secreted molecules that spur chronic inflammation, degrade surrounding tissue structure, and change the behavior of surrounding cells for the worse. Removing these cells quite quickly reverses specific measures of aging and age-related disease in animal models, and the first human trials are underway. Vascular aging is one of the likely areas of benefit - though if there is a mechanism such as autoimmunity spurring more rapid creation of senescent cells, then senolytic treatments will probably have to be correspondingly more frequent.

Autoantibodies against AT1 Receptor Contribute to Vascular Aging and Endothelial Cell Senescence

As a key regulator of vascular physiology, the renin-angiotensin system (RAS) has been implicated in the development and progression of vascular aging. Interruption of the RAS pathway, either by preventing the formation of angiotensin II (Ang II) or by blocking the Ang II type 1 (AT1) receptor, has been proven to be highly successful in retarding vascular aging phenotypes. Meanwhile, inappropriate activation of the RAS, independent of the classic bioactive molecule Ang II, may cause excessive activation of the AT1 receptor and induce chronic inflammation, but how this occurs is not fully understood.

At the end of the twentieth century, a specific autoantibody against AT1 receptor (AT1-AA) was discovered and found to exist in patients with preeclampsia, malignant hypertension, refractory hypertension, and renal-allograft rejection. AT1-AAs could specifically bind to the AT1 receptor and were found to have a receptor agonist-like effect. AT1-AAs were proven to be pro-inflammatory via the transcription factor nuclear factor-kappa B (NF-κB) pathway, thus enhancing the expression of inflammatory factors in endothelial cells (ECs). Moreover, we have previously demonstrated that AT1-AAs induced endothelial damage and contributed to endothelial dysfunction in vivo. Most importantly, AT1-AAs have been reported to accelerate aortic atherosclerosis in mice. A recent study demonstrated that higher AT1-AAs level was associated with inflammation, hypertension, and adverse outcomes. All the above evidence suggests a close relationship between AT1-AAs and vascular aging. Nevertheless, whether AT1-AAs can induce vascular aging or EC senescence has never been explored.

In this study, AT1-AAs were detected in the sera of patients with peripheral arterial disease (PAD) and the positive rate was 44.44% vs. 17.46% in non-PAD volunteers. In addition, analysis showed that AT1-AAs level was positively correlated with PAD. To reveal the causal relationship between AT1-AAs and vascular aging, an AT1-AAs-positive rat model was established by active immunization. The carotid pulse wave velocity was higher, and the aortic endothelium-dependent vasodilatation was attenuated significantly in the immunized rats. Morphological staining showed thickening of the aortic wall. Histological examination showed that levels of the senescent markers were increased in the aortic tissue, mostly located at the endothelium. In addition, purified AT1-AAs-IgGs from both the immunized rats and PAD patients induced premature senescence in cultured human umbilical vein endothelial cells. These effects were significantly blocked by the AT1 receptor blocker. Taken together, our study demonstrates that AT1-AAs contribute to the progression of vascular aging and induce EC senescence through AT1 receptor.

Why Does Reduced Grip Strength Correlate with Chronic Lung Disease in Aging?

In this open access paper, researchers speculate on the common mechanisms underlying the correlation between reduced grip strength and chronic lung disease in old age. The many, complex, and diverse manifestations of aging emerge from a much smaller, simpler set of root causes. Simple forms of damage applied to a very complex system necessarily produce very complex outcomes. Nonetheless, the incidence of many of those outcomes, even when very different from one another, will correlate because they depend to a sizable degree on the same forms of underlying damage.

The term "sarcopenia" was first introduced to describe the progressive age-related loss of muscle mass and is correlated with poor health-related quality of life. In this context, the handgrip dynamometer (HGD) is a useful tool to evaluate muscle strength because it provides simple, fast, reliable, and standardized measurements of total muscle strength. In addition, handgrip strength (HGS) is considered an important measure to diagnose dynapenia because low HGS is a robust predictor of low muscle mass and a clinical marker of poor physical performance.

In the respiratory system, the incidence of chronic lung diseases (CLDs) is comparatively higher in individuals aged 65 and older. HGS is an indicator of overall physical capacity. It is not limited to assessing the upper limbs and is a good predictor of morbidity and mortality, indicating that the HGD is a potentially useful instrument for evaluating different populations with different respiratory conditions. Despite these advantages, HGS is rarely used as a functional measure in patients with respiratory diseases, perhaps because it is erroneously considered a part of a complex battery of functional tests.

Current evidence indicates the presence of different phenomena linking lower muscle mass and function with the occurrence of CLDs in this population. Chronic systemic inflammation is related to nontransmissible CLDs in the elderly, and this inflammatory status may be one of the main links to reduced HGS. In addition to systemic inflammation, other contributors that appear to be important are the chronic effects of hypoxemia due to CLDs, physical inactivity, respiratory and peripheral myopathy, malnutrition, and the use of corticosteroids, which is common in many CLDs. Sarcopenic obesity is increasingly diagnosed in different clinical conditions and may be an important link between decreased HGS and adiposity in CLDs. Reduced HGS in CLDs should be considered a systemic phenomenon requiring a holistic approach to restore physical reconditioning and nutritional status. Therefore, early targeted interventions should be developed in patients with CLDs to delay muscle strength decline and prevent functional limitations and disabilities.

Link: https://doi.org/10.14336/AD.2018.1226

Business Analysts Start to Pay Attention to the Longevity Industry

Larger business analysis concerns are starting to notice that the longevity industry exists. I point out this press release not because the contents are all that interesting or useful - it is very much business as usual in the white paper production community, and the people creating these materials typically have a poor understanding of the biology and the biotechnology - but rather as an indication of progress towards a broader appreciation of the potential to treat aging as a medical condition. Slowly, the eyes of the world are opened.

The global longevity and anti-senescence market will witness rapid growth over the forecast period (2018-2023) owing to an increasing emphasis on stem cell research and increasing demand for cell-based assays in research and development. An increasing geriatric population across the globe and rising awareness of antiaging products among generation Y and later generations are the major factors expected to promote the growth of a global longevity and anti-senescence market. Factors such as a surging level of disposable income and increasing advancements in anti-senescence technologies are also providing traction to the global longevity and anti-senescence market growth over the forecast period (2018-2023).

Senolytics, placenta stem cells, and blood transfusions are some of the hot technologies picking up pace in the longevity and anti-anti-senescence market. Companies and start-ups across the globe such as Unity Biotechnology, Human Longevity Inc., Calico Life Sciences, Acorda Therapeutics, etc. are working extensively in this field for the extension of human longevity by focusing on the study of genomics, microbiome, bioinformatics, and stem cell therapies, etc. Senolytic drug therapy held the largest market revenue share in 2017. The fastest growth of the gene therapy segment is due to the large investments in genomics.

The scope of this report is broad and covers various therapies currently under trials in the global longevity and anti-senescence therapy market. The market estimation has been performed with consideration for revenue generation in the forecast years 2018-2023 after the expected availability of products in the market by 2023. The global longevity and anti-senescence therapy market has been segmented by the following therapies: senolytic drug therapy, gene therapy, immunotherapy, and other therapies which includes stem cell-based therapies, etc. Forecasts from 2028 to 2023 are given for each therapy and application, with estimated values derived from the expected revenue generation in the first year of launch.

Link: https://www.businesswire.com/news/home/20191016005347/en/Global-Longevity-Anti-Senescence-Therapy-Market-Review-2017-2018

Increased Insulin Sensitivity is Not Required for Extension of Healthy Life Span in Mice via Calorie Restriction

The biochemistry surrounding insulin and insulin signaling is very well studied in the context of aging. A number of ways to slow aging in laboratory species involve directly manipulating these signaling pathways. Calorie restriction, like a number of other methods of slowing aging, improves insulin sensitivity, and the consensus in the research community has been that some fraction of the benefits to health and longevity that result from a restricted calorie intake are derived from this change to insulin metabolism. Today's open access paper provides evidence to suggest, surprisingly, that this is not in fact the case. It is possible to block this part of the calorie restriction response, and the effect on health and longevity is much the same.

What, then, are the mechanisms by which calorie restriction produces extension of life span in short-lived species? The evidence to date points towards upregulation of autophagy. Autophagy is the name given to a collection of processes responsible for recycling damaged or unwanted cellular structures and protein machinery. Many methods of slowing aging in laboratory species prominently feature increased autophagy; in principle, cells that are better maintained will experience fewer issues and this results in better tissue function and a slower decline into age-related degeneration. Certainly, it is the case that when autophagy is disabled, then calorie restriction no longer acts to extend life.

Calorie-Restriction-Induced Insulin Sensitivity Is Mediated by Adipose mTORC2 and Not Required for Lifespan Extension

Calorie restriction (CR), a dietary regimen in which calories are reduced without causing malnutrition, extends the lifespan of many diverse species and is the gold standard for interventions that promote the health and longevity of mammals. Importantly, CR extends not only longevity but also healthspan. There has therefore been great interest in identifying the physiological and molecular mechanisms by which CR promotes health and longevity.

In mammals fed a CR diet, one of the most striking and broadly conserved effects is improved sensitivity to insulin. Many dietary and pharmaceutical interventions that extend mammalian lifespan and healthspan likewise promote insulin sensitivity, while conversely, there is a well-known association of insulin resistance with diabetes and poor health. Given the central role of the insulin signaling pathway in the lifespan of worms, flies, and mammals, improved insulin sensitivity has been proposed as an essential mechanism by which a CR diet extends mammalian lifespan. While the effects of CR are systemic, some of its most prominent effects are on adipose tissue; CR reduces adiposity in mammals, mobilizing fat stores in white adipose tissue (WAT) while also activating WAT lipogenesis, which is associated with improved systemic insulin sensitivity and metabolic health.

Despite the strong correlative evidence that CR promotes health and longevity through improved insulin sensitivity, there is clear evidence that insulin sensitivity may not necessarily be essential for healthy aging. Several genetically modified mouse models in which insulin resistance has been induced in one or more tissues have extended lifespan, while mice treated with rapamycin, an inhibitor of the mTOR (mechanistic target of rapamycin) protein kinase that extends lifespan, develop insulin resistance in multiple tissues.

Over the last decade, a critical role for mTOR complex 2 (mTORC2) in the control of organismal metabolism has become apparent. In contrast to the well-known mTOR complex 1 (mTORC1), which functions as a key integrator of many different environmental and hormonal cues, mTORC2 functions primarily as an effector of phosphatidylinositol 3-kinase (PI3K) signaling, contributing to the downstream activation of many kinases, including AKT, by insulin. Deletion of Rictor, which encodes an essential protein component of mTORC2, results in insulin resistance in tissues, including liver, adipose tissue, and skeletal muscle. The organismal consequences of inactivating adipose mTORC2 have been unclear.

While an important role for CR-induced insulin sensitivity in the health and survival benefits of CR has long been assumed, the contribution of improved insulin sensitivity to the benefits of CR has not been directly examined. Here, we have tested the role of CR-induced insulin sensitivity on the metabolic health, frailty, and longevity of mice by placing mice lacking adipose mTORC2 signaling (AQ-RKO) and their wild-type littermates on either ad libitum or CR diets. Critically, the insulin sensitivity of AQ-RKO mice does not improve on a CR diet, enabling us to discern the role of CR-induced insulin sensitivity in CR-induced phenotypes. Although the WAT of AQ-RKO mice has a blunted metabolic response to CR and female AQ-RKO mice fed an ad libitum diet have a slightly reduced lifespan, we find that AQ-RKO mice of both sexes fed a CR diet have increased fitness and extended lifespan. We conclude that the CR-induced increase in insulin sensitivity is dispensable for the effects of CR on fitness and longevity.

Becoming Overweight Raises the Risk of Many Cancers

People who become overweight at younger adult ages have significantly greater cancer risk than their slimmer peers. Visceral fat tissue is very active, producing chronic inflammation through a range of mechanisms including the production of greater numbers of lingering senescent cells. This sort of tissue environment is more hospitable to the development of cancer. Cancer risk is far from the only downside of carrying excess visceral fat tissue, of course: one can expect a shorter, less healthy life on all fronts, accompanied with a raised lifetime medical cost.

Obesity is an established risk factor for several cancers. Adult weight gain has been associated with increased cancer risk, but studies on timing and duration of adult weight gain are relatively scarce. We examined the impact of body mass index (BMI) and weight changes over time, as well as the timing and duration of excess weight, on obesity- and non-obesity-related cancers. We pooled health data from six European cohorts and included 221,274 individuals with two or more height and weight measurements during 1972-2014. Several BMI and weight measures were constructed. Cancer cases were identified through linkage with national cancer registries. Hazard ratios (HRs) of cancer were derived from time-dependent Cox-regression models.

During follow-up, 27,881 cancer cases were diagnosed; 9,761 were obesity-related. The HR of all obesity-related cancers increased with increasing BMI at first and last measurement, maximum BMI and longer duration of overweight (men only) and obesity. Participants who were overweight before age 40 years had an HR of obesity-related cancers of 1.16 and 1.15 in men and women, respectively, compared with those who were not overweight. The risk increase was particularly high for endometrial cancer (70%), male renal-cell cancer (58%) and male colon cancer (29%). No positive associations were seen for cancers not regarded as obesity-related. In conclusion, adult weight gain was associated with increased risk of several major cancers. The degree, timing, and duration of overweight and obesity also seemed to be important. Preventing weight gain may reduce the cancer risk.

Link: https://doi.org/10.1093/ije/dyz188

A Mechanism for Mammalian Cartilage Regrowth is Discovered

A theme of recent years is the discovery of processes of regrowth that operate in mammalian tissues long thought to be non-regenerative. In this case, researchers have found a mechanism of regeneration that operates in cartilage, albeit not to the degree that would be helpful for recovery from more serious injury or the wear of aging. Still, where a mechanism exists at all, it should be possible to find ways to enhance its operation. This work is interesting for the resemblance that this regenerative process bears to the way in which salamanders regrow lost organ tissue. Finding ways to bring that sort of exceptional regenerative capacity into mammals is the subject of numerous research programs.

Contrary to popular belief, cartilage in human joints can repair itself through a process similar to that used by creatures such as salamanders and zebrafish to regenerate limbs. The mechanism for cartilage repair appears to be more robust in ankle joints and less so in hips. The finding could potentially lead to treatments for osteoarthritis, the most common joint disorder in the world.

Researchers devised a way to determine the age of proteins using internal molecular clocks integral to amino acids, which convert one form to another with predictable regularity. Newly created proteins in tissue have few or no amino acid conversions; older proteins have many. Understanding this process enabled the researchers to use sensitive mass spectrometry to identify when key proteins in human cartilage, including collagens, were young, middle-aged or old. They found that the age of cartilage largely depended on where it resided in the body. Cartilage in ankles is young, it's middle-aged in the knee and old in the hips. This correlation between the age of human cartilage and its location in the body aligns with how limb repair occurs in certain animals, which more readily regenerate at the furthest tips, including the ends of legs or tails.

The researchers further learned that molecules called microRNA regulate this process. Not surprisingly, these microRNAs are more active in animals that are known for limb, fin or tail repair, including salamanders and zebrafish. These microRNAs are also found in humans - an evolutionary artifact that provides the capability in humans for joint tissue repair. As in animals, microRNA activity varies significantly by its location: it was highest in ankles compared to knees and hips and higher in the top layer of cartilage compared to deeper layers of cartilage.

"We were excited to learn that the regulators of regeneration in the salamander limb appear to also be the controllers of joint tissue repair in the human limb. We believe we could boost these regulators to fully regenerate degenerated cartilage of an arthritic joint. If we can figure out what regulators we are missing compared with salamanders, we might even be able to add the missing components back and develop a way someday to regenerate part or all of an injured human limb. We believe this is a fundamental mechanism of repair that could be applied to many tissues, not just cartilage."

Link: https://corporate.dukehealth.org/news-listing/humans-have-salamander-ability-regrow-cartilage-joints

Cycles of DNA Damage and Repair as a Cause of Age-Related Epigenetic Drift

Researchers have recently proposed that the normal operation of DNA repair contributes to the epigenetic change that is observed to occur with age. This is an interesting concept, and we'll see how it progresses in the years ahead, particularly as therapies based on alteration of epigenetic markers emerge as an area of active medical research and development.

Epigenetic decorations to DNA are a part of the complex regulatory system controlling the amounts and timing of protein production carried out by a cell. Cells react to changing circumstances with changes to epigenetic markers such as DNA methylation. Some of the alterations in cells and tissues that take place with advancing age, such as rising levels of molecular damage, are very similar between individuals, and thus weighted combinations of the status of specific epigenetic markers can be used to measure age. But most epigenetic change is highly variable and highly individual, dependent on the circumstances that each cell finds itself in, communications with surrounding cells, the overall environment, diet, state of health, and so forth.

At the present time is far from clear as to why exactly most epigenetic changes occur; building the full map and understanding of epigenetic adjustments in response to circumstances will likely still be a going concern decades from now. Even those epigenetic markers used to build biomarkers of aging are not yet firmly connected to specific underlying causes, though work is proceeding towards that end. This uncertainty gives rise to academic and popular debate over where epigenetic change sits in the tangled web of cause and consequence in aging. Programmed aging theorists hold that epigenetic changes are a cause of aging, and reversing them is therefore rejuvenation. Aspects of this view are being voiced more loudly these days, now that certain entities with deep pockets and well-oiled hype machinery are putting venture funding into the development of clinical therapies based on reprogramming cells to have youthful epigenetic patterns.

It would be very surprising to find that epigenetic change is at the roots of aging. The most telling arguments against this are the numerous contributions to aging based on the accumulation of metabolic waste that our biochemistry cannot break down, even in youth. No approach to restoring youthful epigenetic patterns can address that. Epigenetic change can certainly be a proximate cause to all sorts of disarray in aging, however. Reprogramming cells has been shown to restore mitochondrial function, and the general malaise in mitochondria that takes place in all cells in aging tissue can be traced back through failing fission, failing mitophagy, to gene expression levels of specific proteins. Force a cell to produce those proteins at a youthful level, and mitochondria will function once again.

Yet how great a gain can be produced while ignoring the underlying causes? If the history of medicine teaches us anything, it is that efforts to treat age-related disease without addressing its causes have been a miserable failure. Will it really be that much better to take one or two steps closer to the cause, while still not addressing it? That is an important question, and one we are going to see tested in practice, sadly. Enthusiasm and funding for taking those one to two steps is far greater than that for addressing the known root causes of aging.

In this broader context, the work noted here is quite interesting, proposing that the normal ongoing processes of DNA damage and repair taking place in every cell can, over time, produce at least some of the epigenetic changes of aging. They use artificially raised levels of DNA damage and repair to produce accelerated epigenetic change in mice that is at least similar to that of aging.

DNA Damage Leads to Epigenetic Alterations

Despite it long having been the consensus that DNA damage and the resulting epigenetic changes are drivers of aging, some recent studies have questioned the importance of mutations in aging. For example, the number of mutations present in aged yeast cells is fairly low, and some genetically engineered strains of mice with high levels of free radicals or mutation rates do not appear to age prematurely, nor do they have shorter lifespans than their wild-type counterparts.

This appears to suggest that mutational load may not have such a strong influence on aging as was once thought, and the researchers of this new study consider further evidence suggesting the same. They also suggest that epigenetic alterations are perhaps the most important driver of aging and that, far from being random in nature, these changes are predictable and reproducible.

Researchers suggest that DNA double-strand breaks (DSBs) are a possible reason for epigenetic changes and show that there are clues to be found in yeast. In yeast cells, DSBs trigger a DNA damage signal that summons epigenetic regulators and takes them away from gene promoters to the site of the DSB on the DNA, where they then facilitate the repair of the break. The researchers suggest that after these repairs, the regulators responsible for repairing the DSBs return to their original locations on the genome, thus turning off the DNA damage signal, but this does not always happen.

The researchers suggest that with each successive cycle of DNA damage response and repair, the epigenetic landscape begins to change and regulators gradually become displaced, reaching a point where the DNA damage response remains active, leaving cells in a chronic state of stress. This stressed state then causes them to become dysfunctional and ultimately alters their cellular identity.

DNA Break-Induced Epigenetic Drift as a Cause of Mammalian Aging

There are numerous hallmarks of aging in mammals, but no unifying cause has been identified. In budding yeast, aging is associated with a loss of epigenetic information that occurs in response to genome instability, particularly DNA double-strand breaks (DSBs). Mammals also undergo predictable epigenetic changes with age, including alterations to DNA methylation patterns that serve as epigenetic "age" clocks, but what drives these changes is not known. Using a transgenic mouse system called "ICE" (for inducible changes to the epigenome), we show that a tissue's response to non-mutagenic DSBs reorganizes the epigenome and accelerates physiological, cognitive, and molecular changes normally seen in older mice, including advancement of the epigenetic clock. These findings implicate DSB-induced epigenetic drift as a conserved cause of aging from yeast to mammals.

How Much of Sarcopenia Lies in the Nervous System Rather than in Muscle?

Sarcopenia is the name given to the characteristic age-related loss of muscle mass and strength that manifests in all older individuals. A sizable fraction of this decline is self-inflicted, as demonstrated by the gains that can be obtained via resistance training in older individuals. Nonethless, there are inexorable processes of decline, such as the loss of stem cell function in muscle tissue. Researchers have suggested that when it comes to loss of strength, damage and decline in neuromuscular junctions may be to blame, the point of integration between nervous system and muscle tissue. Researchers here suggest that contributing factors could emerge anywhere in the nervous system, including the brain, however.

A recently published study reports findings of a study in which researchers compared how much muscle strength older people could muster voluntarily with how much force their muscles put out when stimulated electrically. The results of this research suggest that physical weakness in aging may be due, at least in part, to impairments in brain and nerve function, rather than changes in the muscles themselves.

The study looked at a group of 66 older adults (average age in their 70s), who were first categorized as severely weak, modestly weak, or strong based on their measured performance on a standardized physical test. In the study, the subjects were asked to push against resistance with their leg extensor muscles, using as much strength as they could generate. When they reached their self-perceived limit, the muscle they were using was then stimulated electrically. If this caused the muscle to put out more force, it was a sign that the strength limitation the person experienced came from somewhere other than the muscle itself.

When the added force that came from electrical stimulation was expressed as a percentage increment, it showed that the weaker the test subjects, the larger a boost their muscles got. The subjects in the "severely weak" group (who were on average older) got an increase of 14.2 percent - twice the 7.1 percent increase shown by those in the "strong" group. When the conventional scientific wisdom linked such weakness mainly to loss of muscle mass, many drug companies looked for medications that acted directly on the muscles, but few proved effective. The new study provides further evidence that the nervous system plays a significant role in the problem.

Link: https://www.eurekalert.org/pub_releases/2019-10/ou-nss100919.php

A Small Clinical Trial of Transcranial Electromagnetic Stimulation Shows Benefits in Alzheimer's Patients

Researchers here report on a small clinical trial of a form of electromagnetic stimulation, claiming reduction in amyloid burden and improvement in cognitive function in Alzheimer's patients. Other approaches to electromagnetic stimulation have been tested in human trials for Alzheimer's disease and failed; the authors here argue that the details of the methodology used matter greatly. It is not unreasonable to expect electromagnetic fields to have effects on cellular metabolism, and there are a range of efforts to try to affect everything from neurodegeneration to wound healing via this class of approach. There is always the question of mechanisms, however: determining how exactly it might be working to affect amyloid levels and cellular behavior, after an effect is confirmed, is a challenging task.

In view of the inability of drugs to slow or reverse the cognitive impairment of Alzheimer's disease (AD) thus far, investigating non-pharmaceutic interventions against AD as a possible alternative is now clearly warranted. Neuromodulatory approaches have consequently emerged and are currently being clinically tested in AD subjects. These approaches include transcranial magnetic stimulation (tMS), transcranial direct current stimulation, and deep brain stimulation. All three approaches provide a generalized stimulatory/inhibitory effect on neuronal activity. The most recent and largest clinical studies involving long-term tMS (Phase III clinical trial) or deep brain stimulation (Phase II clinical trial) in AD subjects have reported minimal or no cognitive benefits.

As the newest neuromodulatory approach against AD, Transcranial Electromagnetic Treatment (TEMT) is very different from tMS because TEMT involves perpendicular magnetic and electric waves emanating away from an antenna/emitter source (rather than magnetic waves radiating from and returning to a conductor in tMS). For our studies, these "electromagnetic waves" are actually within the radiofrequency range (around 1 GHz), which can easily penetrate the human cranium and underlying brain areas.

In a number of pre-clinical studies involving AD transgenic mice, we have administered TEMT daily for up to 8 months. We have demonstrated the ability of TEMT to prevent/reverse both oligomeric and insoluble amyloid-β aggregation - both inside and outside neurons. These TEMT-induced reductions in brain Aβ aggregation are accompanied by brain mitochondrial enhancement and prevention or reversal of cognitive impairment in AD transgenic mice at multiple age. In view of our extensive pre-clinical platform and the aforementioned wide spectrum of human safety studies, clinical trials of TEMT technology in AD were clearly warranted. Therefore, we designed and built a first-of-its-kind head device for administration of TEMT to human subjects in their homes and by their caregivers. The present study reports on safety and efficacy endpoints in an open-label clinical trial to provide daily TEMT to AD subjects over a 2-month period, as well as evaluation at two weeks following completion of treatment.

No deleterious behavioral effects, discomfort, or physiologic changes resulted from 2 months of TEMT. TEMT induced clinically important and statistically significant improvements in the Alzheimer's Disease Assessment Scale-Cognitive, as well as in the Rey Auditory Verbal Learning Test. TEMT also produced increases in cerebrospinal fluid (CSF) levels of soluble amyloid-β, cognition-related changes in CSF oligomeric amyloid-β, a decreased CSF phosphorylated-tau/amyloid-β ratio, and reduced levels of oligomeric amyloid-β in plasma. TEMT administration to AD subjects appears to be safe, while providing cognitive enhancement, changes to CSF/blood AD markers, and evidence of stable/enhanced brain connectivity.

Link: https://doi.org/10.3233/JAD-190367

Kelsey Moody Presenting on the LysoClear Program at Ending Age-Related Diseases 2019

Kelsey Moody of Ichor Therapeutics presented on the LysoClear development program at the Ending Age-Related Diseases conference organized by the Life Extension Advocacy Foundation earlier this year. LysoClear is an example of the commercial development of a rejuvenation therapy, taken all the way from the starting point of the discovery of microbial enzymes capable of breaking down certain forms of harmful age-related molecular waste that contribute to aging and age-related diseases. The actual research is largely done, and the task now is to focus on manufacture, regulatory approval, and entry into the clinic.

Taken end to end, I think that this development program might be able to lay claim to being the first and oldest of the modern rejuvenation research initiatives, starting sometime back in the early 2000s. It began at the Methuselah Foundation as LysoSENS, the first of the SENS programs to get underway with modest philanthropic funding. Some of you may remember gathering dirt from graveyards to send in for analysis, in the hunt for microbial species that consume the molecular waste that our bodies cannot remove. Researches knew that those microbes existed because graveyards do not accumulate this waste - it is being broken down by something in the environment. The program carried forward into the SENS Research Foundation when it spun out from the Methuselah Foundation, and a portion of it was later licensed to Ichor Therapeutics, and became LysoClear.

Kelsey Moody at Ending Age-Related Diseases 2019

Thank you very much for the kind introduction and for the invitation to speak to all of you at this event. It was a great event last year and I'm very excited that we extended it to a two day event this year. I am thrilled to be back. We brought a whole army of our staff, up there in the back, so I'm very excited. Before I dive in, a couple of housekeeping things. Everything I do is for-profit, so financial disclosures: I have a financial interest in everything I am about to talk about. I also need to acknowledge the wonderful team that assisted with building out the research program that I'm going to describe, in particular one of our grad students is in the audience, and a lot of the figures in the work I'm going to be presenting were the result of his extraordinary efforts, so thank you. Also this program is a spin out of Aubrey de Grey's SENS Research Foundation, and received founding investment from Kizoo Technology Ventures - I think Michael Greve is around here somewhere - but thank you guys for getting this off the ground.

Just to give a very brief overview of Ichor Therapeutics in general: Ichor is a vertically integrated biopharmaceutical company, and we, since 2013, have focused exclusively on diseases and mechanisms of aging. Within the Ichor umbrella we have a variety of portfolio companies. Some are platform technologies, some are single asset plays, all of which are focused on different indications and contributing to the field of anti-aging research. Today we're going to focus on our longest-standing program, LysoClear, which is an enzyme therapy that we're developing for age-related macular degeneration, and the subject of my thesis work as well. Age-related macular degeneration is the leading cause of vision loss in individuals over the age of 50. About 200 million people worldwide have this disease. One of the major problems with this disease is that it robs patients of their high acuity central vision that gives them the ability to interact with the world in a meaningful way. If we think about our own lives, vision is really how we interact. We can hear, we can smell, we move around, and are involved in our everyday lives, but vision is a primary means for that. When you look at a geriatric population, that isn't as mobile, can't hear as well, can't smell as well, the devastating effects of macular degeneration are very real. We hope to put an end to that.

Now when we look at the origins of where macular degeneration originates and manifests, anatomically we're talking about the posterior segment of the eye, the retina, which is responsible for all of our vision. At the very back of the eye there is this little indented part of the retina that is called the macula. The retina lets us see, and the little indented part, the macula, is what gives us that high acuity central vision. If we dive in just a little bit closer, we can appreciate that there is a great microanatomy, a lot of crosstalk between a variety of different cellular layers that are responsible for taking light and allowing us to see.

Starting in the vitreous and moving posteriorly, we have a variety of different neural layers that are responsible for the electrochemical signal transduction that gets sent to the brain and we interpret as vision. Further on, we have a variety of different photoreceptors. Those include the rods and the cones. Those are the cells that get hit by light and can kick off that entire cascade. Now a general rule in biology is that if you have a cell type or a system that is repeatedly stressed, in this case the photoreceptors with light, you need to turnover those systems in order to eliminate the accumulation of damage. So the photoreceptors are supported by very critical phagocytic cell called the retinal pigmented epithelium or RPE. These cells are essential for photoreceptor function and survival. The photoreceptor outer segments are constantly growing towards the upper RPE and the RPE are constantly gobbling off little bits of the photoreceptors in an effort to turn them over.

Like any cells in the body, the RPE cells' phagocytic potential is really based on the lysosome, the organelle that is responsible for degrading things. LIke any other cell in the body, like any other lysosome in the body, a normal healthy lysosome has a plethora of different enzymes that are able to break down all of the little bits of stuff that make up us. However, there are cases where this doesn't function properly. Canonically we're thinking about lysosomal storage diseases. These are congenital diseases where patients are born missing one of those essential lysosomal enzymes. A lot of the time these diseases are lethal in utero, but for the patients who are born with these diseases, the clinical manifestation can be very, very severe. The patients accumulate molecular junk uncontrollably and can't do anything about it. Our central hypothesis for how macular degeneration works is that age-related macular degeneration is an evolutionarily silent lysosomal storage disease, driven by a very specific sort of junk accumulation called lipofuscin. In the context of retinal lipofuscin, it is a combination of retinoid derivatives and lipids. When I say "evolutionarily silent" I mean that in our evolutionary history we haven't lived long enough to accumulate enough of this junk to evolve enzymes able to break it down. But in our view, the onset and progression of macular degeneration is very akin, mechanistically, to what we see in conventional lysosomal storage diseases, and this is going to be a central theme for how we approach treating the disease, and our translational pathway.

Lipofuscin accumulates in the lysosomes of these essential support cells, the RPE. In the very earliest stages of macular degeneration progress, we don't see anything clinically at all, because it is all happening inside of the cell. But at some point in time, lipofuscin accumulates to a level sufficient to promote pathology. It crosses a threshold and problems start to emerge. I've got two types of figures here. The ones on the left are fundus images, which is when you take an ophthalmoscope and look right into the back of the eye and snap a picture. We can see the optic nerve coming through and this little darkened area here is the macula. If we were to take a cut cross-section through the back of the eye and then flip it and look at that cross-section, then that's what these images on the right are. It is called optical coherence tomography, OCT.

As lipofuscin accumulates in the RPE cells, eventually the RPE cells start to become dysfunctional and choke on the accumulating lipofuscin. To cope with the stress, they do what cells need to do - they dump the junk. So the brightest white line here is the RPE layer, and we can see these bumps underneath it. Those are extracellular junk deposits that the RPE are laying down. We call those drusen. So lipofuscin: junk in the cells; drusen: the junk outside the cells that the cells are depositing. We can also see this very easily clinical via fundus imaging, we just look and we see all these little white specks. All of those are drusen in the back of the eye.

Now what is important to note about this, in this early-stage mild form of age-related macular degeneration, we maintain a nice concave morphology of the macula. We also have integrity in the RPE layers, and in the photoreceptors above them. Even though we have this junk being deposited, even though we see these morphological changes happening, usually there is no clinical presentation of this because the photoreceptors that are required to see are not yet disrupted. As the disease progresses, however, eventually the RPE cannot handle the stress burden and the cells start to die, and with them the photoreceptors that rely upon them. So we see by OCT the thinning of the RPE and photoreceptor layers, we see a collapse of the nice morphology of the macula. Because of this thinning, when you look by fundus imaging you can see the choroid, the blood vessel layers at the back of the eye. That presents as geographic atrophy.

This is the intermediate form of age-related macular degeneration, and, collectively, mild and intermediate are termed dry or atropic macular degeneration. Which suggests that there is a wet form. As these cells are dying and having all kinds of problems, it creates a pro-inflammatory environment in which you have complement activation, an immune response, and, importantly, hypoxia. Part of the way that the body attempts to cope with this mess is to create new blood vessels. New blood vessel formation occurs at the choroid, and protruding into the eye. When you have new blood vessels in the body, frequently they are very leaky vessels, so you can have exudate and outright hemorrhage, either into the subretinal space, which can lead to retinal detachment, or into the vitreous itself, which can lead to total blindness. This process of neovascularization is called neovascular or wet age-related macular degeneration, and this is the most severe and advanced form.

So our disease model hypothesis is that lipofuscin, which accumulates inside of the RPE cells, so intracellular stress, drives the accumulation of extracellular drusen. This in turn causes ROS, inflammation, complement activation, hypoxia, and then these stressors eventually lead to the disease state. Our goal at LysoClear is to develop an enzyme therapy that targets lipofuscin at the earliest stages of disease onset and progression. How are we going to go about doing that?

It is first of all important to note that there is no good standard of care for this disease, and, by the way, the dry form is about 90% of patients. Only 10% have the advanced wet form. So for 90% of patients there are no FDA approved drugs. They do have a vitamin formulation that will mildly reduce your risk of progessing, and if you are a smoker you should not be smoking, for this among many other reasons, but it is really not until you get to the really severe form that there is any sort of really efficacious treatment regimen. These are mostly monoclonal antibodies that target the VEGF pathway to inhibit further neovascularization. So there is a huge overwhelming need for more effective treatments for this condition.

I mentioned previously that we're viewing age-related macular degeneration in a manner akin to conventional lysosomal storage disease. So we are wondering if we can borrow some aspects of how we will treat a normal lysosomal storage disease, and with that motif put together a strategy for going after AMD. What is that strategy? Well if your lysosomal storage disease is based on the idea of missing an enzyme in the lysosome, then at the high level it is a simple process: you make the missing enzyme, and you introduce it in such a way that it goes to the lysosome of the target cells. This has been developed and has been approved clinically, and used very successfully by Genzyme. It has been a conventional way to treat lysosomal storage diseases since the 1990s.

The pathways that are used: you make your enzyme, you decorate it in such a way that it gets recognized by a receptor on your target cell, mannose 6-phosphate glycosylation is the canonical delivery path for lysosomal enzymes to reach the lysosome. Mannose receptor is another pathway that is used, and then through an endocytosis pathway your enzyme is able to be selectively delivered to the lysosome. So this is how lysosomal storage diseases are treated. The problem is that we don't have any good human enzymes that are able to break down RPE lipofuscin. We aren't supposed to. We've never evolved them. So we can't rely on human enzymes to facilitate this junk removal. Instead we have to look elsewhere in the world.

That is where SENS Research Foundation (SRF) came in. Some years ago SRF said that this is a problem, and this is the canonical LysoSENS paradigm: here is a junk accumulation, let's look for enzymes that can break it down and remove the junk. By way of wonderful research by John Schloendorn and his team, SRF identified identified a variety of fungal peroxidases, among other enzymes, that are capable of breaking down certain lipofuscin components. The specific component that they looked at was a molecule called A2E - again, lipofuscin is comprised of a variety of retinoids and lipid derivatives. A2E is one of the best studied and most resistant to degradation, and so that is what SRF used for their assays. They identified a bunch of enzymes that can break down A2E from wild-type sources.

This is where we came in. Our goal was to take this very encouraging proof of concept research and build a program to establish a proof of concept that we could actually remove lipofuscin both within cells and within animals to pave the way for moving into patients for the first time. The first thing we needed to do is to get out of a wild-type system - there is just a lot of variability when dealing with wild-type enzymes. So we moved into a recombinant system to make the best performing enzyme, manganese peroxidase. We expressed that enzyme in the yeast strain Pichia pastoris. The reason for that is that Pichia preferentially mannosylates unlinked glyosylation sites, so Pichia automatically adds those sugars to the enzyme that we need for it to be delivered into the cell.

When we make our enzyme and run a gel, we see a beautiful big smear, which is characteristic of hyperglycosylation, and when we treat our enzyme with PNGase F, an enzyme that selectively cleaves off all of your sugars, we see a nice tightening of the band at the expected molecular weight of about 54 kDa, suggesting that we have an enzyme that is indeed glycosylated. Of course we wanted to know how many sugars we have, so we sent the sugar trees out for glycoanalysis and identified 26 mannose residues on the sugar chain. For context, for those of you who aren't glycobiologists, and neither am I, you probably want two to five mannose sugars minimum to achieve uptake optimally - though depending on the enzyme you can go more or less than that.

So, ok. We have an enzyme, it has the sugars that are required for delivery. The next step is that we need to figure out its selectivity against lipofuscin targets. I mentioned to you that lipofuscin is a hodgepodge of different things, and the hardest part of it to break down are these retinoids, vitamin A derivatives. Unfortunately, it is not just one thing but many things. So we scoured the literature and synthesized all of the major lipofuscin components that we could find. We tested our recombinant enzyme using our local HPLC, and we showed that our enzyme is actually able to break down every single lipofuscin component that we tested. Now this isn't entirely surprising, because these are all chemically related species, so we would have expected the enzyme to work similarly on these different species. We have EC50 variants of 1 μmol all the way up to 20 μmol; interestingly, A2E, the molecule that SRF did their screen with, was the most resistant to degradation by the enzyme. As I move forward and present both the cell based work we did and some of the in vivo work, we are going to use A2E as the readout, quantitatively, and the reason for that it is the easiest to analyze, it is the most resistant to degradation, so we believe we are under-reporting the effectiveness of the enzyme by using the hardest target to degrade.

One of the problems that we ran into very very early with this program is that, go figure, cells outside the body behave a little bit differently than they do when they are in the body. So although RPE cells have mannose receptors in vivo, and this is very well established, the second you take those cells out and grow them in culture, the receptor disappears, which makes it really difficult to use that as a model for update and delivery of your drug. So we had to split the efficacy and the uptake into separate experiments. For efficacy, we used a canonical line of RPE cells, ARPE-19. The graph on the left shows them to be negative by flow cytometry for mannose receptor, that is what CD206 is. So what we did is that we had a layer of these cells, untreated they are high viability. When we added excessive levels of A2E as a stressor, we see that the viability drops, and then we saw that our manganese peroxidase is able to rescue some of that viability when we had A2E loaded cells and treated them with the enzyme.

The way that we delivered the enzyme for these studies is with a lipid reagent called BioPORTER, a way of forcing the enzyme artificially into the cell. So this isn't our proposed delivery system, this is just asking the question of if we could get the enzyme into the cells, would it be able to protect against some of this retinoid toxicity, and indeed it seems that it can. Then of course we did manganese peroxidase by itself just to make sure it wasn't toxic, and we have a bunch of other studies along these lines as well, and we see that it doesn't different in any meaningful way from the untreated cells.

We then had to ask the separate question, which is whether the uptake is able to occur through a mannose receptor dependant manner. The cell line that we used for this is a mouse monocyte line called RAW 264.7, which is known to have an intact mannose receptor and mannose receptor endocytosis pathway. For this study we started off with mannosylated bovine serum albumin that was flourescently conjugated and we added that to the cells and looked by flow cytometry for an increase in fluorescence. That is the solid pink line here. So we see over time an increase in fluorescence, which we interpret as internalization of the enzyme by our target cell. When we introduce the competitive inhibitor mannan, which also binds to mannose receptor, we see an attenuation of that effect size, suggesting that we're impairing the uptake, and that this is in fact a mechanism by which the enzyme is entering cells. We then did the exact same thing for our recombinant manganese peroxidase, again we think it has mannose because we checked that, and we also fluorescently labelled it. In much the same way we see an increase in the fluorescence of the enzyme, and we can reduce that signal by competing with mannan, suggesting that the increase in fluorescence is mediated by mannose receptor endocytosis.

Next we really wanted to get to this proof of concept point: are we able to remove or degrade existing lipofuscin components like A2E in vivo. There has been a lot of work showing that you can kind of shovel it around or maybe reduce the rate of its accumulation, but no-one to my knowledge has ever shown that you can actually get rid of it and break it down. So that is really what we wanted to get to as a primary inflection point. We ran an intravitreal pharmacokinetics study, and this is just where we injected the vitreous with our enzyme, did sampling measured by ELISA, and identified a half-life of about 9.6 hours. That is great because this is supposed to be a highly targeted enzyme that just goes into these highly phagocytic RPE cells, so we would expect a pretty short half-life. Indeed, we don't want an enzyme that is hanging out there for no particular reason. We want it to be internalized rapidly - versus monoclonal antibody therapies, which are acting on extracellular targets, and where you'd be looking for a half-life measured in days. So we're very excited by that.

We then asked the big question: can we actually have efficacy? To do this, we used a mouse model of age-related macular degeneration, and the juvenile onset form Stargardt's disease. This is an ABCA4-null mouse, and these mice accumulate accelerated levels of A2E. So what we did, we had our mice and we injected them with six doses of either phosphate buffered saline (PBS), low dose enzyme, or high dose enzyme. We see a little bit of a trend, maybe, on the low dose, but nothing significant, and then at the high dose we saw a significant reduction in A2E burden as measured by analytical HPLC.

We wanted to do an intermediate dose, so we redid a separate experiment, where we treated with PBS and an intermediate dose of the enzyme. We did see a statistically significant drop there. When we pull this data together, we see a nice dose-response in our efficacy model in terms of reduction of our molecular target when treated with increasing doses of our enzyme. So collectively we're really excited about this. We've shown that manganese peroxidase is able to break down all lipofuscin fluorophores that we've tested, we've shown that it can be taken up into cells by way of mannose receptor endocytosis, and, most importantly, for the first time to my knowledge, we're actually able to eliminate existing lipofuscin in an in vivo system.

These results were published in December 2018, and later on that same month we successfully closed a financing round for our LysoClear program, to take these very promising lead series, and engineer them into clinical candidates. All of that work is ongoing at Ichor Therapeutics, I'm very excited about it. Our rate-limiting step right now is actually that we need to move into large animal models for safety, toxicity, and so on, to inform a pre-IND meeting with the FDA. I'm super-excited that my large animal vivarium is scheduled to complete construction in the next three weeks, so hopefully we'll have some very exciting data coming out for our next presentations on this topic.

Many Longevity Enhancing Interventions Work via Upregulation of Autophagy

Many, possibly even most, longevity enhancing interventions tested to date in short lived species produce their effects on aging and life span via an increase in the cellular maintenance processes of autophagy. The major focus of the research community over the past few decades in the matter of aging has been to replicate some of the calorie restriction response, or other responses to cellular stress. Cells responds to lack of nutrients, excessive heat, and so forth, by undertaking greater maintenance efforts for an extended period of time. If the stress is mild and transient, the result is a net benefit. Unfortunately this class of approach doesn't have sizable effects on life span in long-lived species such as our own: if we want to live significantly longer in good health, then we need to look at other strategies, such as rejuvenation biotechnologies after the SENS model that repair the forms of cell and tissue damage that causes aging.

In the past two decades, the molecular signatures of aging have been started to be uncovered. A remarkable conservation of these cell signaling pathways has been shown across various invertebrate and vertebrate species. Autophagy is a cellular process that has emerged as a nexus at which these various pathways have been shown to converge. Autophagy is the catabolic process by which the cell eliminates unnecessary cellular components to maintain energy homeostasis and prevent the build-up of toxic material.

Autophagic activity has been shown to decline with age in various animal models. For example, body-wide quantification of autophagic flux in Caenorhabditis elegans revealed a general decline in activity in various tissues, including the intestine and neurons. A similar decline in function has been observed in mammals. For example, electron microscopy analysis of aged mouse livers revealed a depression in the rate of autophagic vesicle formation.

Various groups have identified a necessary role of autophagy in mediating the effects of longevity-enhancing mutations. Inhibiting autophagy in a long-lived mutant model nullifies the longevity-promoting effects of the mutation. C. elegans worms that carry a loss-of-function mutation in their daf-2 gene, which encodes for a common single insulin/Insulin-like Growth Factor (IGF)-1 Receptor in this organism, live significantly longer than their wild-type counterparts. RNAi-mediated knockdown of the autophagy gene bec-1 significantly reduced the lifespan of the daf-2 mutants, clearly identifying autophagy as a process that is required for the increased longevity of this mutant.

To demonstrate a causal relationship between autophagy and longevity, some groups have evaluated the effects of overexpressing autophagy genes. A positive relationship between autophagic activity and lifespan was first demonstrated in Drosophila. Neuron-specific overexpression of the Atg8a gene resulted both in an increase in lifespan and a reduction in the accumulation of toxic protein aggregates in neurons. Similarly, body-wide overexpression of Atg5 resulted in a significant increase in lifespan in mice. Increase in autophagy via disruption of the beclin1-BCL2 complex has been shown to promote both healthspan and lifespan in mice. In summary, autophagy has convincingly been shown to play a pivotal role in healthspan and lifespan extension.

Link: https://doi.org/10.3389/fcell.2019.00183

Chronic Inflammation as a Contributing Cause of B Cell Decline in Aging

B cells are important to the coordination of the immune response. Dysfunctional B cells emerge with age, however, leading to autoimmunity and contributing to immunosenescence, the name given to the general age-related decline in effectiveness of the immune system. Animal studies have shown that selective destruction of the entire B cell population is beneficial in older individuals, improving the immune response: the cells are quickly replaced, but the harmful portion will take much longer to reemerge. Setting all of this to one side, the open access review here is largely focused on more subtle changes in the B cell population and its production in the bone marrow, driven by the effects of age-related chronic inflammation on stem cells and progenitor cells.

The alterations of the B-cell compartment in aging have been evaluated by contrast to B-cell physiology in young adults. Overall, B-cell generation and function demonstrate large similarities between young mice and humans. In the more detailed mouse context, B cells arise from uncommitted progenitors nested in the bone marrow. Overall, aging disturbs B-cell development in the mouse bone marrow. Strikingly, aging seems to introduce a high mouse-to-mouse variability in early progenitor B cellularity compared to young mice. Impaired B-cell development occurs as a result of affected RAG and SLC expression, as well as decreased sensitivity to IL-7 signals. The in-depth situation in humans remains to be established. Nevertheless, available studies suggest that the amount of B cells decreases, although proportions of progenitor and mature B subpopulations may not be substantially changed in the aged bone marrow.

Various clues point at a role for inflammation in the altered B-cell development in aging, albeit the data is generally based on similarities with acute inflammatory responses. Indeed, pro-inflammatory senescent cells as well as terminally differentiated CD8+ effector T cells accumulate in the bones of old mice and humans respectively. Correspondingly, concentrations of pro-inflammatory molecules or their production by cells are increased in bone marrow during aging. The balance between the negating effects of anti-inflammatory cytokines and the intensity, as well as variety, of pro-inflammatory molecules expressed could contribute to the observed variability in the deterioration of early B-cell development in susceptible aged organisms.

Inflammation can affect the differentiation of multi-lineage hematopoietic progenitors. Thus, aged mouse and human hematopoietic stem cell (HSC) physiology is altered and the output of this compartment reveals a bias against the production of lymphocytes due to the accumulation of stem cells with a propensity to differentiate into myeloid cells. This limits the production of B cells. Persistent inflammation in aging could also compromise the differentiation of B lineage-restricted progenitor cells. A major effect of aging is the repression in B cells of the expression and/or activity of the transcription factors E2A and EBF1, which control the RAG and SLC genes.

Despite the alteration of the B-cell compartment in the bone marrow, the cellularity of mature B cells in the spleen is comparable between aged and young mice. However, this apparent stability masks underlying disparities in the distribution of mature B-cell subsets. The situation in humans appears more difficult to appreciate, since most studies performed analyses based on blood samples, which have an inherent variability and may not reflect mature B-cell representation within tissues. Altogether, the B-cell fraction in the blood of elderly people appears decreased and the proportions of naïve and memory subsets altered. Similar to the bone marrow, various inflammatory molecules could influence the distribution of mature B-cell populations.

Link: https://doi.org/10.1159/000501963

Is Displaced Nuclear DNA a Meaningful Cause of Chronic Inflammation in Aging?

Sterile inflammation arises without external cause, such as infection or injury, and chronic sterile inflammation is a characteristic of aging. Inflammatory signaling becomes constant and pronounced in tissues, and the immune system is constantly roused to action. Processes, such as regeneration from injury, that depend upon a clear cycle of inflammation that starts, progresses, and resolves are significantly disrupted. It is no exaggeration to say that the downstream consequences of chronic inflammation accelerate the progression of all of the common age-related conditions. It is of great importance in atherosclerosis and neurodegenerative conditions, for example. Like raised blood pressure, chronic inflammation is one of the more important mechanisms acting to convert the low-level molecular damage at the root of aging into the various proximate causes of age-related disease and mortality.

Thus the research community is greatly interested in understanding how and why sterile inflammation arises in later life. Cellular senescence is one sizable area of investigation, as senescent cells accumulate with age, and secrete inflammatory signals. Additionally, visceral fat tissue acts to increase the pace at which senescent cells arise, but also contributes to inflammation via other mechanisms. In the short open access commentary here, the authors discuss a potential mechanism whereby cells in aged tissues start to eject DNA fragments from the cell nucleus, and this can cause reactions that lead to inflammatory signaling. This is probably important in cellular senescence, but may also operate in other cells.

Damaged DNA marching out of aging nucleus

Subclinical but heightened inflammation in the absence of infection is a key feature of aging, and includes senescent cells that secrete cytokines. Yet, what are the intrinsic processes that initiate 'inflammaging', and possibly other forms of sterile inflammation, like autoimmunity? Self-DNA has long been suspected as trigger and target of autoimmunity, as anti-nuclear antibodies, anti-dsDNA (double-stranded DNA) antibodies and plasma DNA are observed in autoimmune patients of lupus and rheumatoid arthritis.

In studying the initiating events leading to autoimmune arthritis in mice deficient for the lysosomal nuclease DNASE2A, we revealed an unexpected 'hidden' source of this inflammatory DNA - the cell's own nucleus. In healthy cells, damaged and irreparable nuclear DNA fragments are trafficked to the cytosol, enclosed by autophagosomes, and delivered to the lysosomes for degradation by DNASE2A. Lacking DNASE2A, extranuclear DNA accumulates in cells and induces inflammation via innate DNA sensing. Cytosolic DNA sensing is activated when dsDNA binds the DNA sensor enzyme cGAS (cyclic GMP-AMP synthase), converting GTP and ATP into the endogenous second messenger cGAMP, which in turns activates the adaptor protein STING (stimulator of interferon genes) and induces innate immune responses and inflammation. Nuclear DNA as a trigger of immunity could help explain a range of inflammatory conditions.

As cells age, damaged DNA accumulates over time. As an interesting aside, anti-dsDNA antibodies are also found at higher levels in older adults. Could damaged DNA march out of the nucleus of an old cell to set off inflammaging? Indeed, in replicative and oncogene-induced senescent cells, damaged nuclear DNA is exported. Clearing DNA is perhaps the most effective way to eliminate its inflammatory danger. As the only known acidic DNA endonuclease, DNASE2A preferentially degrades dsDNA. It resides with the lysosome, where intracellular and extracellular DNA cargoes converge for degradative digestion. In mice, Dnase2a-deficient cells exhibits the typical senescent phenotype of enlarged cells, slow cell growth, and increased expression of aging markers (senescence-associated β-gal activity, p16 and HP1β expression). Indeed, ectopic expression of DNASE2A substantially reduces cytosolic DNA abundance, innate immune activation and cellular aging phenotype in old cells, thus confirming the protective role of enzymatic DNA degradation in limiting inflammation.

Growing evidence now supports a unifying theory that damaged or irreparable DNA leaves the nucleus to drive aging-related inflammation via innate DNA sensing. Where DNA damage is increased (aging), DNA repair inhibited (ataxia), or nuclear barrier compromised (progeria), DNA load may be not reduced promptly or sufficiently, leading to inflammation. So how far can this DNA theory help to understand the cellular immune mechanisms underlying aging? Each nucleus holds a massive reservoir of endogenous DNA that can trigger local and systemic immunity if there are internal abnormalities such as DNA damage. How nuclear DNA export, trafficking, sensing, and degradation is coordinated to maintain cellular homeostasis is largely unknown. DNA danger coming from within generates exciting questions that probe into the basic life cycle of broken DNA fragments, and suggest ways of treating self-DNA-mediated sterile inflammation (autoimmunity, cancer, neurodegeneration, and chemotherapy) by regulating the abundance of mis-localized DNA.

Investigating the Superior DNA Defenses of Tardigrades

Tardigrades are extremely resilient to radiation induced DNA damage, and here researchers delve into some of the mechanisms involved. Mining other species for potential improvements to our own biochemistry, or the basis for therapies, is an expanding line of work in the life science community. Possible ways to improve mammalian defenses against damage to nuclear DNA are of interest for a range of reasons, not least of which is that it is the present consensus that stochastic mutation to nuclear DNA contributes to both cancer risk and aging itself, as mutations in stem cells or progenitor cells can spread throughout tissues via clonal expansion.

Tardigrades, which are also known as water bears or moss piglets, are small invertebrate animals that are found in marine, freshwater, and terrestrial habitats throughout the Earth. Terrestrial tardigrades require a thin film of water to remain active. In the absence of water, they undergo anhydrobiosis into a dormant dehydrated state from which they can be rehydrated to an active form. In the anhydrobiotic state, tardigrades are resistant to extreme conditions of heat, cold, vacuum, pressure, radiation, and chemical treatments. Remarkably, they have been found to survive exposure to the vacuum and radiation of outer space.

The tardigrade Ramazzottius varieornatus contains a unique nuclear protein termed Dsup, for damage suppressor, which can increase the resistance of human cells to DNA damage under conditions, such as ionizing radiation or hydrogen peroxide treatment, that generate hydroxyl radicals. Here we find that R. varieornatus Dsup is a nucleosome-binding protein that protects chromatin from hydroxyl radicals. Moreover, a Dsup ortholog from the tardigrade Hypsibius exemplaris similarly binds to nucleosomes and protects DNA from hydroxyl radicals.

Strikingly, a conserved region in Dsup proteins exhibits sequence similarity to the nucleosome-binding domain of vertebrate HMGN proteins and is functionally important for nucleosome binding and hydroxyl radical protection. These findings suggest that Dsup promotes the survival of tardigrades under diverse conditions by a direct mechanism that involves binding to nucleosomes and protecting chromosomal DNA from hydroxyl radicals.

Link: https://doi.org/10.7554/eLife.47682

The Upheaval in Alzheimer's Research and Clinical Development

It seems that the tipping point has been reached in the Alzheimer's research and development community, in the sense that it is becoming more widely accepted that new approaches are needed. The failure to produce significant benefits to patients via clearance of amyloid from the brain by immunotherapy has spurred a great deal of theorizing, and several new and promising lines of work. For example, working on restoring age-related declines in drainage of cerebrospinal fluid might remove all metabolic waste from the brain. Alternatively, a focus on neuroinflammation and the role of dysfunctional microglia is suggested, particularly by studies of senolytics showing benefits in mouse models resulting from removal of senescent microglia. The monolithic focus on amyloid is giving way to a period of greater experimentation and diversity in clinical development, and this can only be a good thing when it comes to making progress towards effective treatments for Alzheimer's disease.

In the last five years, as several large clinical trials testing drugs for Alzheimer's disease failed, the field came to a stark conclusion: These approaches did nothing to slow down - let alone reverse - the course of the disease once patients already exhibited symptoms of early dementia. The failed trials, along with the dawning realization that the disease unfolds over decades, have put the entire field on a reset-to develop and test interventions that can be used much earlier, to discover new targets beyond misfolded amyloid and tau proteins, and to fund large, interdisciplinary, big data collaborations.

Aging is by far the biggest risk factor for developing Alzheimer's - if everyone lived to be 85, one in two people would develop dementia. The lion's share of Alzheimer's research and drug discovery to date has focused on misfolded amyloid and tau proteins, which aggregate to form plaques (amyloid) and tangles (tau) in the brain. But the body's attempt to clear the sticky proteins might also be contributing to or causing the neurodegeneration. Drug trials have almost exclusively sought to use antibodies targeted toward these two proteins to try to attack and clear the misfolded forms or mop up soluble forms, or to inhibit enzymes responsible for generating the miscreant peptides.

New areas being explored include the vascular system, epigenetics, neuroprotection, synaptic health, immunity and inflammation, and metabolic dysfunction, among others. Neuroinflammation and proteostasis, or the management of proteins within cells, are trending areas of research. Another booming area of Alzheimer's research is the development of biomarkers and diagnostic tests to monitor disease presence and progression. Radioactive positron emission tomography (PET) tracers enable physicians to image and measure amyloid and tau proteins in the brains of living patients. Other biomarkers can be measured precisely from collecting cerebral spinal fluid. However, both types of tests are invasive, and PET scans are expensive. "We need a blood test like the one we have for cholesterol that can be done in any doctor's office quickly and inexpensively."

Link: https://www.sciencemag.org/features/2019/10/alzheimers-research-reset

Lipid Metabolism in Aging and Age-Related Disease

Lipids are everywhere in our biochemistry. Where they are present in cell structures and molecular mechanisms that are important to any specific age-related disease, or are among the underlying root causes of aging, it will tend to be the case that differences between species (and possibly individuals) can lead to changes in the pace of aging and disease. For example, lipid composition determines resistance to oxidative damage to cell membranes. A range of evidence supports the membrane pacemaker hypothesis of aging, in that longer-lived species tend to have more resilient cell membranes, based on their lipid composition.

Today's open access paper uses lipids as an anchoring point for a wide-ranging discussion on aging, biomarkers of aging, and the differences in aging between species. The authors are, I feel, justifiably pessimistic about the prospects for the eventual production of therapies based on most of the means to slow aging demonstrated in short-lived laboratory species. There are indeed radical differences between the biochemistry of short-lived species and long-lived species such as our own. Yet even when mechanisms are in fact proven to be much the same in all of worms, flies, mice, and humans, as is the case for calorie restriction and its upregulation of cellular maintenance processes, we cannot expect that therapies will automatically be effective enough to justify development. The practice of calorie restriction extends life in mice by up to 40%, but while it improves health in humans, it certainly doesn't significantly extend human life span in the same way.

The role of lipid metabolism in aging, lifespan regulation, and age-related disease

Due to the sheer amount of time and cost required to validate a study in humans, the bulk of our aging and lifespan data come from shorter-lived yeast, worms, flies, and rodents. With the exception of research showing that caloric restriction improves health and survival in rhesus monkeys, little aging work has been done in longer-lived organisms. The bulk of our understanding regarding aging comes from genetic experiments in model organisms, and we do not yet know how similar or dissimilar human aging is. Rather than screen every lifespan-extending intervention in humans to better understand how human aging works, another approach would be to utilize aging biomarkers.

Biomarkers that strongly correlate with aging, lifespan, and healthspan can teach us about which processes are involved in human aging. Ideally, a robust and practical biomarker would be one that incurs a low monetary cost and can be measured safely, repeatedly, and easily. Blood draws are especially appealing because they are inexpensive, simple, low risk, and can be taken as needed throughout a patient's lifetime. While several biomarker studies have focused on protein-based markers, the advancement of metabolomic techniques has made it feasible to look closely into a large array of metabolites. Metabolomic lipids and lipid-related proteins represent a large, rich source of potential biomarkers that are easily measured in the blood. Compounds in lipid metabolism can take many forms, such as phospholipids, triglycerides, waxes, steroids, and fatty acids. They also play diverse physiological roles, such as forming cell membranes and exerting powerful cell signaling effects. Lipids are perhaps the most well-known for the paramount roles they play in both the storage and mobilization of energy.

Although lipids have been traditionally treated as detrimental and as simply associated with age-related diseases, numerous studies have shown that lipid metabolism potently regulates aging and lifespan. For example, researchers assessed the plasma lipidomic profiles of 11 different mammalian species with longevities varying from 3.5 to 120 years. They found that a lipidomic profile could accurately predict an animal's lifespan and that, in particular, plasma long-chain free fatty acids, peroxidizability index, and lipid peroxidation-derived product content are inversely correlated with longevity. Evidence from animals with extreme longevity also links lipid metabolism to aging. The ocean quahog clam Arctica islandica, an exceptionally long-lived animal that can survive for more than 500 years, exhibits a unique resistance to lipid peroxidation in mitochondrial membranes. Naked mole rats, which enjoy remarkably long lifespans and healthspans for rodents, have a unique membrane phospholipid composition that has been theorized to contribute to their exceptional longevity.

A plethora of dietary, pharmacological, genetic, and surgical lipid-related interventions extend lifespan in nematodes, fruit flies, mice, and rats. For example, the impairment of genes involved in ceramide and sphingolipid synthesis extends lifespan in both worms and flies. The overexpression of fatty acid amide hydrolase or lysosomal lipase prolongs life in Caenorhabditis elegans, while the overexpression of diacylglycerol lipase enhances longevity in both C. elegans and Drosophila melanogaster. The surgical removal of adipose tissue extends lifespan in rats, and increased expression of apolipoprotein D enhances survival in both flies and mice. Mouse lifespan can be additionally extended by the genetic deletion of diacylglycerol acyltransferase 1, treatment with the steroid 17-α-estradiol, or a ketogenic diet.

In humans, blood triglyceride levels tend to increase, while blood lysophosphatidylcholine levels tend to decrease with age. Specific sphingolipid and phospholipid blood profiles have also been shown to change with age and are associated with exceptional human longevity. These data suggest that lipid-related interventions may improve human healthspan and that blood lipids likely represent a rich source of human aging biomarkers.

An Interview with Justin Rebo of BioAge

BioAge is one of a growing number of companies using machine learning methods to reduce cost and speed up discovery of drug targets, development of small molecule drugs, or peptides, or other aspects of traditional medical development than have been painfully costly, inefficient, and slow. Faster, cheaper processes in medical development are a benefit to humanity, and right now the novelty of this sort of work gives it a high profile in the entrepreneurial and investment communities. Faster and cheaper isn't a substitute for choosing the right strategy for the development of therapies to treat aging, however.

After all, every therapy for aging prior to the development of senolytics to clear senescent cells was fairly marginal in its benefits. Many of the therapies presently under development in the longevity industry alongside the targeted destruction of senescent cells will also be marginal, because, unlike senolytics, they fail to meaningfully reverse a cause of aging. Producing marginal therapies at an accelerated rate is not a success story. Better infrastructure will only efficiently help the end goal of greatly extended healthy life span when coupled to a program of research and development that aims to repair the molecular damage that lies at the root of aging.

I was wondering if you could briefly explain how BioAge verifies whether the aging targets they identify are valid?

BioAge begins with human data. We find human cohorts that have banked blood samples from decades ago, coupled with electronic health records that have followed those people ever since, in some cases, until their deaths. We send these blood samples for deep omics profiling: proteomics, metabolomics, transcriptomics, stuff like that. From that, we can find what's in the blood, for instance, the transcription profiles of the blood cells and soluble protein metabolites, which is correlated with age-related diseases and mortality. That's only part of the picture, of course, because that doesn't tell you what's causal, it only tells you what's correlational. So, from there, we adopt a systems biology approach where we connect the results to whatever datasets we can find out in the world or among those we generate ourselves, which gives us a few extra clues. However, ultimately, the only way we can really verify if a target is valid is by testing it experimentally, and so that's what we do. After we pull everything together data-wise, that only gives us so much. We really need to test these targets in animal models as well as cell models, but we prefer to test in vivo.

Since research budgets are limited, what is your view on how these budgets should be allocated across these differing priorities, i.e. should the identification of biomarkers for more diseases or the development of interventions take precedence if we need to choose, and why?

That's how BioAge started: the whole point was to generate biomarkers. At the same time, these so-called biomarkers are often themselves druggable targets. Part of the evolution of BioAge as a company is that first we find these biomarkers, and then we turn them into drugs. In terms of how society should allocate resources (biomarker research versus the development of interventions), we personally don't have to consider that as much, seeing as we're doing both in-house. I can't really say what anyone else should do, but I think we found something that works for us.

Aubrey de Grey's idea is that if we develop a therapy for one subtype of causative damage of aging, it will be much easier to extend that therapy to similar types of damage. Since BioAge is working on using computational approaches to find the molecular pathways that drive aging, I was wondering if you are using a similar type of clustering approach to facilitate faster intervention development?

To some extent, because I love Aubrey's integrated approach. For me, personally, his 'seven deadly things' talk was kind of my introduction into the field back in 2004/2005. But BioAge, at least initially, takes an opposite approach in the sense that we don't cluster things. We look for mortality as our first differentiating factor. Any target that we look at as something that we might want to pursue must be associated with mortality, and mortality is really as broad as it gets. That being said, once we've screened for mortality, we then examine what specific disease indications would make the most sense. I can't really get into detail about what those are. But I like the way we look broadly at the data first, in a kind of "hypothesis-free" sense, with an open mind, letting the data speak for itself.

Link: https://www.leafscience.org/an-interview-with-dr-justin-rebo/

An Interview with Amutha Boominathan of the SENS Research Foundation

Amutha Boominathan leads the mitochondrial research program at the SENS Research Foundation, focused on achieving allotopic expression of mitochondrial genes. This is the process of placing mitochondrial genes into the nuclear genome, suitably altered so that the proteins produced are transported back to mitochondria where they are needed. Every cell contains a herd of hundreds of mitochondria, the descendants of ancient symbiotic bacteria that contain a remnant circular genome. Mitochondria are responsible for packaging chemical energy store molecules, but are also deeply integrated into many other cellular processes.

Thirteen mitochondrial genes remain in the mitochondrial DNA, the source of proteins vital to the correct operation of these organelles, but far more vulnerable to damage and mutation than nuclear DNA. That damage and mutation is one of the root causes of aging, leading to dysfunctional cells that pump harmful oxidative molecules into the surrounding tissue. Adding backup genes to the cell nucleus should work around this issue by allowing mitochondria with damaged DNA to continue functioning, as they will still receive the necessary proteins.

Your research group started developing an improved method for allotopic expression of mitochondrial DNA in 2015 that has already shown very promising results?

The major hurdle that we have overcome is, at least, showing protein products for all the 13 genes. We made some fundamental changes to all 13 genes with a uniform approach, but that approach may not work equally well for all of them. We may have to engineer each one of them for specific properties. So, all of these 13 genes differ with respect to their length, their hydrophobicity, and the complexes that they target. The main hurdle is actually the hydrophobicity factor. These 13 proteins are normally synthesized within the mitochondrial matrix, and they are inserted into their complexes. But, in allotopic expression, they are synthesized in the cytosol and have to traverse two membranes and then go to the right location. We will have to engineer them one after the other or modify them in such a way that it recognizes the right pathway. So, like I said, we are causing global changes to all 13 genes, and we will cause specific changes to each one of them to make it functional as a whole. The first step is to at least see a product, and that's what we've overcome now.

What have been the criteria for selecting mitochondrial DNA genes to work on for allotopic expression?

One of the other hurdles is proving that your technology actually works, and for that, you need model systems. The reason we were able to show that ATP8 really works is because we were able to get a patient cell line with a severe mutation that's null for the ATP8 protein. Usually, in humans, mutations to mitochondrial genes manifest in various levels, but it is unusual that the protein is completely absent in the patient. It's a rare event. But mitochondrial DNA exists in heteroplasmy. There are wild type and mutant levels, both present continuously, and it's the tipping factor that causes a disease phenotype to ensue. The one reason we were able to really convincingly show ATP8 works is because we were able to get the null cell line and show that the exogenous protein goes into the right location and regains many of the functions that were absent before. Basically, you have the cell line available, which is really rare. So, let's make use of it.

What do you think will be a realistic timeframe for therapies targeting mitochondrial DNA mutations to reach humans?

They are actually already doing that but with the recoded version. That means we already have a precedent. All we have to show is that our version of it is better and that ours has a better immune profile. That's also why we want to do it in animal models, so we can actually show how it's better. I don't know about the timeframe; that's a very difficult question. If the animal studies go well, I want to say five years. Not five years before it reaches people, but five years to establish enough proof of principle that we can start to develop this for people.

In your view, what does aging research need most right now to ensure it can make the most significant leaps that the field is capable of in the coming 10 years?

I think you need good biomarkers. That's lacking in the field. Everybody wants to have a quick fix. They have all these different areas that they think are very important to aging, but I don't think that's the way it is. I think it's more like a general breakdown of everything with time. So you need better markers, and maybe even a better mindset where it's okay to be healthy in old age. People shouldn't be resigned to the fact that they will age with time and that they are going to die. Maybe a little more public education is needed to accept that it's okay to want and to have a healthy lifespan.

Link: https://www.leafscience.org/an-interview-with-dr-amutha-boominathan/

The SENS Research Foundation on the Beneficial Nature of Senolytic Therapies

The SENS Research Foundation should need no introduction to this audience, but, just in case, this is one of the few non-profit organizations dedicated to advancing the state of the art in rejuvenation research and development. The focus of the SENS Research Foundation staff is on unblocking lines of research that are presently moving too slowly, rather than on reinforcing success. The co-founder, Aubrey de Grey, assembled the Strategies for Engineered Negligible Senescence (SENS) going on twenty years ago. It was, and is, a synthesis of what is known in the research community regarding the root causes of aging. In the SENS model, a cause of aging is a form of damage that occurs and accumulates as a result of the normal operation of cellular metabolism.

Among these causes of aging is the accumulation of senescent cells, cells that should be destroyed, but linger to cause harm via their inflammatory signaling. It took more than a decade for the suggestion in the SENS proposals that senescent cells should be targeted for destruction to emerge as a well supported line of research, and that required a great deal of advocacy and bootstrapping behind the scenes. The field has advanced considerably since then, and at an accelerating pace. Today, numerous biotech companies are developing what have come to be known as senolytic therapies, capable of selectively destroying senescent cells. There is overwhelming evidence from animal studies for senolytics to be beneficial - to extend healthy life, and more importantly to significantly turn back age-related disease and dysfunction at a late stage. This year, the first clinical trials provided initial data to show that senolytic therapies should function in the same way in humans.

On occasion, the SENS Research Foundation staff publish answers to questions from the community. This month, the topic is clearance of senescent cells, and whether not it is an unalloyed benefit. Is there any reason we should hold back from periodically clearing all lingering senescent cells in old tissues? The animal data so far suggests few caveats; the downsides remain largely theoretical rather than actual, while the upsides are self-evident. The essay is well supported by references; you should read it all, not just the excerpt shown here.

Question of the Month: Senolytics - Solution or Self-Defeating for Senescent Cells?

This month's question from the community: when senolytic drugs cause senescent cells to die, other (younger) cells need to divide and take the place of the dead cells. This cell division causes telomere shortening, thus possibly creating new senescent cells. How is it that the process of killing senescent cells is not self-defeating if new senescent cells are being created?

There are a couple of ways to come at this question. The first is to just look at the astonishing beneficial effects of senolytic drugs or gene therapies in aging mice and mouse models of age-related disease. In these studies, senolytic drugs have restored exercise capacity and capacity to form new blood and immune precursor cells in aging mice to near youthful norms, while preventing age-related lung hypofunction, fatty infiltration into the liver, weakening or failure of the heart, osteoporosis, and hair loss. These treatments have also prevented or treated mouse models of diseases of aging like osteoarthritis, fibrotic lung disease, nonalcoholic fatty liver disease, atherosclerosis, cancer and the side-effects of conventional chemotherapy, as well as neurodegenerative diseases of aging like Parkinson's and Alzheimer's diseases ... and on and on! So whatever collateral damage might ensue from ablating senescent cells, it's pretty clear that senolytic treatments are doing a lot more good than harm.

But let's drill down on the underlying reasoning of the question a little more. Suppose (as the question posits) that every time you destroy a senescent cell, a progenitor cell (one of the partly-specialized tissue-specific cells that repopulate a tissue with mature cells specific to that tissue) replicates to create a new cell to take its place. In fact, studies do show that when senescent cells are killed in a tissue, the progenitor cells begin to multiply and/or to function better as stem cells. This benefit is not due to the progenitor cells automatically replicating themselves and taking the place of the senescent cell, but because the baleful secretions spewed out of senescent cells inhibit the progenitor cells' regenerative function, such that destroying senescent cells allows the progenitor cells to begin working properly again. This is observed in blood-cell-forming cells, cardiac progenitor cells, bone-forming cells, and the cells that form new fat cells - in both mice and now (in a small, short-term clinical trial) even in humans!

So does this support the worry behind the question? Not really. It just takes a moment's thought to realize that just one such replication can't possibly be enough to drive a stem/progenitor cell into senescence. Still, even if a single round of senolytics isn't enough to drive your stem cells senescent, what if you turn one tissue stem cell senescent for every two times they are triggered to proliferate by senolytic therapy - or every three, or four, or ten? Might a single round of senolytic drugs be a net benefit, whereas repeated treatments over a lifetime would deplete tissue stem cells step by step, eventually riddling the body with senescent cells and leaving the patient (murine or human) worse off over the long term? Fortunately, we have long-term studies to address that question - and they tell us again that the answer is "no."

Mitochondrial Mutator Mice May be a Poor Model

Mitochondrial dysfunction and mitochondrial DNA damage are significant features of aging. One of the tools used to investigate the role of mitochondria in aging is the lineage of mitochondrial mutator mice. These mice accumulate mutations in mitochondrial DNA quite rapidly, and exhibit accelerated aging. Setting aside the discussion of what exactly qualifies as accelerated aging, researchers here present evidence to suggest that the mitochondrial mutation is not the cause of accelerated aging in this model. Instead, this particular approach to accelerating mitochondrial DNA damage leads in addition to accelerated nuclear DNA damage. This is consistent with the many other forms of accelerated aging that are caused by breakage of DNA repair mechanisms, and thus faster accumulation of unrepaired mutation in nuclear DNA.

The conclusion here is that mitochondrial mutator mice are a poor model, possibly just this model, possibly the entire class of such models as they stand, not that mitochondria are less relevant to aging. There is far and away too much evidence to dismiss mitochondrial damage and dysfunction as a cause of degenerative aging. If anything, this brings the mutator mice in line with other mouse lineages with high levels of mitochondrial mutation, as those do not display accelerated aging - their mechanisms of breakage are presumably not significantly impacting nuclear DNA mutation rates.

Mitochondria are small powerhouse organelles that have their own DNA, the mitochondrial DNA (mtDNA). For almost half a century, mitochondrial DNA mutations and oxidative stress have been asserted as major contributors to aging, as postulated in the mitochondrial theory of aging published in the 1970s. The theory has been tested on the mtDNA Mutator mice that have an inactive DNA repair mechanism. These mice accumulate mtDNA mutations and present with accelerated aging, which has led scientists to believe that mtDNA mutagenesis drives aging. However, despite rigorous studies by several groups, no one has been able to show that the Mutator mice would present elevated oxidative stress.

The prematurely-ageing Mutator mice harbour a defective polymerase-gamma enzyme and present with pronounced mtDNA mutagenesis. Despite the existence of other mouse models with equivalent mtDNA mutagenic propensity, the Mutator mouse model is the only one manifesting accelerated aging. Furthermore, progeria is not a clinical feature of mitochondrial disease patients, not even in those with the most severe mtDNA mutagenic profiles. Rather, the clinical picture of the mtDNA Mutator mice is remarkably similar to that of other mouse progeria models and human progeric syndromes with nuclear genome instability, with the most prominent defects in proliferating cells, and especially in stem cells and progenitor cells important for tissue regeneration.

The new study shows that in addition to the mtDNA maintenance defects, the Mutator mice also manifest nuclear DNA defects, including replication fork stalling, increased DNA-breaks and activation of DNA damage response pathways. So, how can a primary mitochondrial DNA maintenance defect affect the maintenance of nuclear genome? Nucleotides are the building blocks of DNA, and proper cellular nucleotide levels are critical for genome maintenance. Moreover, the cytoplasmic and mitochondrial nucleotide pools are interconnected. The researchers show that in the Mutator mice, the total cellular nucleotide levels are decreased, while the mitochondrial nucleotide pools are increased, suggesting preferential usage of nucleotides in the mitochondria. Indeed, the replication of mtDNA is drastically accelerated in the cells of the Mutator mice.

Link: https://www.uef.fi/en/-/uusi-tutkimus-haastaa-kasityksia-ennenaikaisen-ikaantymisen-mekanismeista

Deletion of p38α in Neurons Slows Neural Stem Cell Decline and Loss of Cognitive Function in Mice

Researchers here provide evidence for p38α to be involved in the regulation of diminished neural stem cell activity with age. It is thought that the loss of stem cell activity with age, throughout the body and not just in the brain, is an evolved response to rising levels of damage that serves to reduce the risk of cancer that arises from the activity of damaged cells. The cost, however, is a slow decline into dysfunction and tissue failure. There are many therapeutic approaches under development in labs and startups that involve ways to force stem cell populations to go back to work, overriding their normal reaction to an aged environment. While this is nowhere as good a class of approach as repairing the underlying damage of aging, some of these types of therapy may turn out to produce large enough benefits to be worth the effort.

Neurogenesis occurs in the subgranular zone of the dentate gyrus (DG) in the hippocampus and the subventricular zone (SVZ) of the lateral ventricle in the adult mammalian brain. Adult hippocampal neurogenesis arises from neural stem cells (NSCs) within the DG. NSCs give rise to intermediate progenitor cells, which divide generating immature neurons that subsequently integrate into the local neural network as granule cells. Accumulating evidence suggests that adult-born neurons may play distinct physiological roles in hippocampus-dependent functions such as memory encoding and mood regulation. Age induces a decline in adult NSC activity and neuronal plasticity, which could partially explain some age-related cognitive deficit symptoms. Neuronal loss or dysfunction also contributes to the onset of age-related neurodegenerative pathologies.

Increasing evidence reveals that NSC activity is regulated by intrinsic and extrinsic factors. Among the latter, it has been recently shown that neuronal activity controls NSC quiescence and subsequently neurogenesis in the hippocampus. The molecular mechanism by which neuronal activity contributes to the regulation of NSCs, and whether this decreases with aging, remains unknown.

p38 mitogen-activated protein kinase (p38MAPK) is an important sensor of intrinsic and extrinsic stresses and consequently controls key processes of mammalian cell homeostasis such as self-renewal, differentiation, proliferation, and death. In the brain, p38MAPK signalling is activated during neurodegenerative diseases and in response to brain injury. Its genetic or pharmacological inhibition ameliorates symptoms of neurodegenerative diseases and protects against ischemia. The p38MAPK family comprises four members, with p38α and p38β being expressed at high levels in the brain. p38α has been involved in inflammation and environmental stresses, and there is evidence implicating p38α in neuronal function and cognitive activity with contradictory results.

Using mice, we demonstrate that genetic deletion of p38α in neurons suffices to reduce age-associated elevation of p38MAPK activity, neuronal loss and cognitive decline. Moreover, aged mice with genetic deletion of p38α present elevated numbers of NSCs in the hippocampus and the subventricular zone. These results reveal novel roles for neuronal p38MAPK in age-associated NSC exhaustion and cognitive decline.

Link: https://doi.org/10.1111/acel.13044

The Many Roles of Senescent Cells

Long-lived senescent cells accumulate with age, initially quite slowly as they are efficiently removed by the immune system when their own programmed cell death processes fail, but once the immune system starts to decline with age, the burden of cellular senescence ramps up dramatically. Senescent cells secrete a potent mix of signals known as a senescence-associated secretory phenotype (SASP). It spurs chronic inflammation, destructively remodels nearby tissue, encourages nearby cells to also become senescent, and causes all sorts of other issues as well. It is very harmful, and the more senescent cells there are, the worse the consequences.

Fortunately, the research and development communities have finally woken up to the fact that senescent cells are an important contributing cause of aging. Numerous animal studies have demonstrated rejuvenation, reversal of specific age-related conditions and measures of aging, via the targeted destruction of senescent cells, using senolytic therapies of one form or another. Human trials of first generation senolytics are underway and the first results were published this year. Some of those compounds are cheap and readily available, and we might hope that they will be pushed into the clinic quite soon as people realize just how beneficial they might be. Meanwhile, startup biotech companies are developing what will hopefully be better second generation treatments, to arrive in the clinic in the years ahead.

Senescent cells do actually have a number of beneficial purposes. They are involved in regeneration from injury, in suppression of cancer, and embryonic development. Fortunately all of these are short-term roles, and thus do not conflict with a strategy of periodic clearance of lingering senescent cells. A senescent cell in its proper time and place emerges, does its job, and then is destroyed quite soon thereafter. It is the few that stick around for the long term that are the problem, and destruction is the most straightforward approach to take; it aligns with the outcome that our biochemistry attempts for all senescent cells,but fails for the lingering few.

Cellular senescence in development, regeneration and disease

Cellular senescence is a form of permanent cell cycle arrest that can be induced in primary cells in response to a variety of stimuli. Senescence was first discovered in primary cells that were grown for extended periods in culture, reaching what became known as a state of replicative senescence, the cellular equivalent of old age. Subsequently, it was shown that cells exhibiting markers of senescence accumulate in aging tissues, further linking the senescence process with aging. Later, a landmark study identified that the expression of active oncogenes (such as those encoding mutant Ras) in primary cells could induce senescence prematurely, in a process now known as oncogene-induced senescence (OIS). This introduced the concept that senescence might function as a tumor-suppressive mechanism to block the aberrant proliferative effects of oncogenic mutations in cells.

Following on from this, many diverse stress-inducing stimuli including irradiation, chemotherapy, cytokine treatment and even induced pluripotent stem cell(iPSC) reprogramming have been shown to induce a senescent response in a variety of cell types. In summary, senescence functions as a cellular process that prevents the proliferation of old, damaged and potentially tumorigenic cells, but the consequence of which is increased aging at the organismal level. Although the regulated induction of senescence is beneficial in preventing tumor formation, prolonged aberrant persistence of senescent cells can have detrimental effects in promoting cancer. For example, if the timely clearance of OIS cells by the immune system is perturbed, this leads directly to tumor formation. Similarly, although chemotherapy can, in part, exert beneficial effects by inducing tumor-cell senescence, the persistence of therapy-induced senescent cells can, via the SASP, promote tumor recurrence and metastasis.

The senescence process has long been linked to aging, including in the original study demonstrating that aging human skin has increased numbers of cells that are positive for the senescence marker senescence-associated beta-galactosidase (SA-ß-gal). In recent years, perhaps the most conclusive data linking senescence with organismal aging has come from the use of senescence 'deletor' mouse models, in which cells expressing p16INK4A are selectively targeted for elimination. In such models, the removal of senescent cells results in significant improvements in health and vigor, and also in lifespan. These studies unequivocally demonstrate how the accumulation of senescent cells during aging can have a negative impact on health and lifespan.

Much of what we understand about senescence has been extrapolated from studies of disease or aging. However, more recent discoveries of beneficial roles for senescence in non-disease conditions has helped to create a clearer understanding of the physiological function of senescence. Beneficial roles for senescent cells have been described in various conditions of wound repair. After wounding, the deposition of extracellular matrix (ECM) aids the repair process but, if excessive, can result in fibrosis, which subsequently impairs proper repair. Senescence has been demonstrated to have a role in wound repair and the fibrotic response in a number of tissues.

The discovery of cells exhibiting markers and features of senescence in developing embryos was an exciting finding. This was primarily based on studies describing senescent cells in mouse embryos. However, cells bearing some or many features of senescence have also been described in human embryos. Interestingly, in many cases, senescent cells were found in signaling centres, with the secretory function of these structures contributing to cell fate specification and tissue patterning. The emerging details suggest that senescent cells may have multiple functions in the embryo. Senescent cells that appear in the embryo arise in very precise patterns in time and space, appearing during specific time windows, before subsequently disappearing, demonstrating that the induction, presence and removal of these cells is a tightly controlled programmed cellular process.

Senescence is also intricately linked with cellular reprogramming, with studies of iPSCs providing key clues. Indeed, expression of the four reprogramming factors Oct4, Sox2, Klf4, and Myc (OSKM) causes widespread induction of senescence markers in cells that ultimately do not undergo reprogramming, whereas those that successfully reprogram manage to silence key senescence mediators. Interestingly, induction of reprogramming in tissues also activates a senescence response, but in cells adjacent to those that undergo reprogramming. It appears that the SASP, and in particular IL6 from the senescent cells, enhances OSKM activity and reprogramming in nearby cells.

Combining Strategies to Slow Aging to Increase Life Span in Flies by 48%

The research and development communities have little incentive to try combinations of approaches when it comes to intervening in the aging process, or indeed to treat any medical condition. There is little funding and large barriers stand in the way of any effort to combine either existing or novel therapies, such as issues with intellectual property rights. Thus few groups undertake such work. Which is a pity, because one would expect there to be synergies between therapies targeting two different mechanisms affecting the same condition in many cases, or at least for the treatments to be additive in effect.

The example here is interesting as a demonstration of such synergies between approaches, but it is worth recalling that the upregulation of stress response mechanisms via nutrient sensing used as a target here is a strategy known to have a far smaller impact on life span in long-lived species than in short-lived species. Extending life in flies by 48% is still not something that would necessarily indicate that any significant gains in human life span are possible via this methodology.

Increasing life expectancy is causing the prevalence of age-related diseases to rise, and there is an urgent need for new strategies to improve health at older ages. In organisms ranging from invertebrates to mammals, reducing the activity of the nutrient-sensing mechanistic target of rapamycin (mTOR) and insulin/insulin-like growth factor signaling (IIS) network can promote longevity and health during aging. Lowering network activity can also protect against the pathology associated with genetic models of age-related diseases. The network contains many drug targets, including mTOR, mitogen-activated protein kinase kinase (MEK), and glycogen synthase kinase-3 (GSK-3). Down-regulation of mTOR activity by rapamycin, GSK-3 by lithium, or MEK by trametinib can each individually extend lifespan in laboratory organisms, and brief inhibition of mTOR has recently been shown to increase the response of elderly people to immunization against influenza.

An advantage of pharmacological interventions is that the timing and dose of drug administration are relatively simple to optimize, and drugs can be easily combined. Here we show that trametinib, rapamycin, and lithium act additively to increase longevity in Drosophila. Because rapamycin, lithium, and trametinib extend lifespan by at least partially independent mechanisms, we investigated the effects on lifespan of their double and triple combinations.

Double combinations of lithium and rapamycin, lithium and trametinib, or rapamycin and trametinib produced a reproducibly greater lifespan extension than controls, on average 30%, compared to each compound alone, which extended lifespan by an average of 11%. Remarkably, the triple drug combination increased lifespan by 48%. Furthermore, the combination of lithium with rapamycin cancelled the latter's effects on lipid metabolism. In conclusion, a polypharmacology approach of combining established, prolongevity drug inhibitors of specific nodes may be the most effective way to target the nutrient-sensing network to improve late-life health.

Link: https://doi.org/10.1073/pnas.1913212116

The Search for Factors in Young Blood that Might be Used to Treat Aging

A fair number of research groups and a few startup companies are engaged in the search for factors in young blood that might explain the effects of parabiosis. Heterochronic parabiosis is a procedure in which the circulatory systems of a young and an old mouse are linked. The young mouse begins to show some early signs of aging, and the old mouse shows a reversal of some measures of aging. The evidence to date is conflicted on the topic of whether or not this effect is due to beneficial components of young blood: it is clearly the case that some signals present in young blood can be delivered on their own to old animals in order to produce benefits; yet blood and plasma transfusions don't seem to work to any meaningful degree in either mice or people; and a very compelling study provided evidence for benefits to result from a dilution of harmful factors in old blood.

Scientists initially used parabiosis to investigate how conjoined organisms, like some twins, affect each other. After a period of declining interest in the method starting in the 1970s, parabiosis returned to the scene in 2005, when scientists decided to use the approach to answer questions about tissue regeneration in older organisms. After the release of the 2005 study and other work showing that young blood could seemingly rejuvenate old mice, scientists and the public alike seized on the alluring notion of an elixir of youth.

In February, concerned about premature application in humans based on findings in mice, the US Food and Drug Administration cautioned against young plasma transfusions, noting that they have "no proven clinical benefit" for age-related or other diseases in humans. In the wake of the initial fervor surrounding young blood, researchers are taking a more measured approach. Rather than trying to reverse aging, they're identifying the molecular factors responsible for the changes seen in parabiosis experiments in hopes of targeting specific diseases associated with aging.

The relative abundance of aging and regenerative factors in our bodies shifts as we age. At birth, our blood contains more regenerative factors - like oxytocin, which has been shown to rejuvenate skeletal muscle stem cells in mice - than aging factors. But as we get older, that balance gradually tips in favor of aging factors, like the protein eotaxin, thought to play a role in age-related diseases in which systemic inflammation occurs. Aging factors lower our ability to maintain and repair tissue structure and function, while regenerative factors raise it.

Some researchers who study aging think that young blood could point us to more than just regenerative factors for treating disease. Research to slow or halt aging is more complex than searching for regenerative factors in blood. In parabiosis, animals share not only a circulatory system but also their immune and organ systems, making it difficult to rule out these systems' influence on aging or rejuvenation. Researchers developed a parabiosis-like technique that allows mice to exchange only blood. When the researchers used the technique to connect young and old mice, they found that after each mouse had equal parts old blood and young blood circulating through it, the young mouse displayed negative effects. Old blood drastically decreased hippocampal neuron generation, learning and agility, and liver regeneration in young mice.

Young blood, on the other hand, showed no significant benefits for cognition, agility, or the generation of hippocampal neurons in old mice. In other words, the secret to stalling aging may not lie in boosting rejuvenating factors but instead in blocking factors in old blood that promote aging - ones that hinder tissue maintenance and repair. Researchers have turned their focus to TGF-β, a protein that increases with age. A recent study showed that pharmacologically normalizing the activity of the TGF-β pathway, which is elevated in old age, while adding the rejuvenating factor oxytocin improves muscle regeneration, enhances hippocampal neuron growth, and boosts cognition.

Link: https://doi.org/10.1021/acscentsci.9b00902

Data on Exercise as a Treatment for Age-Related Arterial Stiffness

In addition to its effect on muscle growth, exercise upregulates a range of maintenance processes, such as autophagy, that improve tissue function when maintained over the long term. Lack of exercise in later life accelerates the decline in muscle mass and strength, an issue that appears reversible to a degree that might surprise most people. A similar situation occurs with respect to stiffening of blood vessels, in that while much of this depends on mechanisms such as cross-linking and presence of senescent cells, some of the decline is a matter of being sedentary.

The interesting finding in the open access study noted here is that while long term physical exercise is associated with lower blood pressure and lesser degrees of arterial stiffness, having sedentary people undertake short term exercise programs doesn't help in this matter. This can be compared with other studies in which exercise very rapidly improves matters, such as in the case of memory function.

We can speculate as to what this tells us about the importance of various different causes of arterial stiffness, and the authors of the paper do just that. For our part, we might also think of this in the context of data that shows interventions such as nicotinamide riboside and MitoQ, approaches that improve smooth muscle cell function, act to reduce arterial stiffness somewhat. Smooth muscle is the tissue responsible for contraction and dilation of blood vessels, and some fraction of stiffness arises from dysfunction in this tissue. One would certainly expect exercise to act through a similar improvement in smooth muscle function, but apparently that isn't the case in the short term.

Exercise and Arterial Stiffness in the Elderly: A Combined Cross-Sectional and Randomized Controlled Trial (EXAMIN AGE)

Cardiovascular diseases are responsible for the majority of deaths in western countries and age has been identified as a main risk factor. Vascular tissue biomarkers such as arterial stiffness (AST) provide a means of optimized risk assessment to detect individual subclinical organ damage. Commonly measured as central pulse wave velocity (PWV), AST has gained clinical importance and has been proven to be a reliable predictor for cardiovascular (CV) risk in the general population. Altered PWV indicates subclinical target organ damage and may be used to quantify cumulative damaging effects of CV risk factors on the aging arterial wall integrity.

Previous studies on the effect of regular physical activity and exercise on indices of AST in the elderly have reported conflicting results. High-intensity interval training (HIIT) is an exercise modality that has attracted attention for its potency to increase cardiorespiratory fitness and reduce CV risk in patients, for example, with metabolic syndrome. Data on HIIT and its effects on PWV are scarce. Previous evidence suggests that HIIT may be superior regarding reductions in AST compared to moderate aerobic training in young patients with increased CV risk. However, a recent meta-analysis could not detect differences in AST reduction between the two training regimens.=

Our aim was to investigate the associations between long-term physical activity and central PWV in healthy and diseased elderly. Our study results demonstrate the importance of long-term physical activity and the limited impact of short-term exercise training on large artery stiffness in an older population. Long-term physical activity was associated with lower central PWV even in the absence of CV risk factors. Most importantly, 12-weeks of HIIT did not reduce PWV in elderly at increased CV risk.

Aging is characterized by continuous remodeling of the arterial wall, and higher cardiorespiratory fitness may mitigate stiffening of the aging arterial tree. In our study, with every 10 ml/min/kg increase in VO2max, PWV dropped by 0.8 m/s. Active participants presented with 0.5 m/s lower central PWV than their sedentary counterparts. An increase of 1 m/s in central PWV has been associated with a 15% risk increase in CV and all-cause mortality. Thus, our cross-sectional findings indicate an 8% risk increase attributable to a sedentary lifestyle even in healthy elderly.

Our results demonstrate that long-term active compared to sedentary lifestyle is associated with lower AST even in healthy elderly. This suggests that age- and disease-related vascular stiffening and the associated worse CV outcome can be postponed by long-term regular physical exercise. Short-term exercise, even at higher intensities, cannot improve arterial stiffening in sedentary elderly with increased CV risk. Exercise-induced reductions of AST seem to depend on a concomitant decrease of blood pressure.

Reduced Levels of TOM1 as a Proximate Cause of Neuroinflammation in Alzheimer's Disease

Researchers here provide evidence for lower levels of TOM1 observed in Alzheimer's disease to be a proximate cause of chronic inflammation in the brain, and suggest that therapies to raise TOM1 levels might dampen inflammation to a great enough degree to be useful to patients. The inflammation and disarray in the brain's immune system, particularly microglia, is implicated in a range of neurodegenerative conditions. In the case of Alzheimer's disease it remains debatable as to where neuroinflammation sits in the chain of cause and consequence: is it a result of amyloid-β aggregation, a necessary step that leads to the much more harmful tau aggregation that characterizes the later stages of the condition, or does it also directly cause amyloid-β aggregation? Both might be the case - there are a great many two-way interactions in aging.

As we age, the innate immune system becomes dysregulated and is characterized by persistent inflammatory responses, and the chronic inflammation mediated by inflammatory receptors represents a key mechanism by which amyloid-beta (Aβ) drives the development of cognitive decline in Alzheimer's disease (AD). A crucial aspect of this process is a failure to resolve inflammation, which involves the suppression of inflammatory cell influx and the endocytosis of inflammatory receptors.

To decipher the mechanism associated with its pathogenesis, we investigated the molecular events associated with the termination of IL-1β inflammatory responses by focusing on the role played by the target of Myb1 (TOM1), a negative regulator of the interleukin-1β receptor-1 (IL-1R1). We first show that TOM1 steady-state levels are reduced in human AD hippocampi and in the brain of an AD mouse model versus respective controls. Experimentally reducing TOM1 affected microglia activity, substantially increased amyloid-beta levels, and impaired cognition, whereas enhancing its levels was therapeutic.

This data shows that reparation of the TOM1-signaling pathway represents a therapeutic target for brain inflammatory disorders such as AD. A better understanding of the age-related changes in the immune system will allow us to craft therapies to limit detrimental aspects of inflammation, with the broader purpose of sharply reducing the number of people afflicted by AD.

Link: https://doi.org/10.1073/pnas.1914088116

An Interview with Sergey Young of the Longevity Vision Fund

The Longevity Vision Fund is the third of the sizable pools of venture funding to emerge of late, after Juvenescence and Life Biosciences, that are dedicated to the new longevity industry. Unlike the other two, the Longevity Vision fund is initially focused on what I would say are initiatives that don't much matter and won't much move the needle on human aging. Only in their second phase do they intend to invest in classes of biotechnology and therapy that may include high value approaches.

Despite the way in which senolytics to remove harmful senescent cells outperform everything else to date in reversal of aging and age-related disease, we are still, it seems, somewhat early in the phase of spreading the understanding that repair based strategies are the only real way forward to sizable gains in human health and life span in old age. Aging is damage and repair of that damage is rejuvenation - as a steering principle, this is still not yet widely adopted. As a result a great deal of funding is going to be used on projects that do very little of consequence in the matter of aging. At a conference not so long ago, I mentioned this to a wealth manager, who shrugged and said that there is so much potential funding on the sidelines, tipping towards becoming involved, that it doesn't much matter - just fund everything with a credible team and let the chips fall where they may.

There so many things that make longevity investment risky. Not only is it subject to all of the translational risks seen in more traditional biotech investing, but we're also so early on in the game that its hard to tell if any of it will live up to its promise. Let's say I'm a nervous first-time investor in longevity - you run one of the biggest funds in this space, give me some tips on how you assess risk.

Longevity is a new and exciting field, which does bring certain risks - but at the same time, the potential is unmatched. We are currently undergoing a massive Longevity Revolution, where how medicine is practiced, drugs are developed, is changing. Tech giants are becoming our new healthcare providers. Medicine is becoming more personalized. I am often invited to speak at longevity and private wealth conferences, where investors ask me the same question. I start by explaining my personal "3 Horizons" framework to help map the longevity space: Horizon 1: technology currently available that has the potential to expand our lifespans to 100 years, such as DIY diagnostics, wearables, digital healthcare delivery, medical software and apps; Horizon 2: emerging technology with the potential to expand our lifespans to 150 years, such as genome therapy and editing, stem cell therapy, nano-robots, AI-based diagnostics and drug discovery, smart hospitals; Horizon 3: age reversal, brain-computer integration, avatars, Internet of the Body.

We invest across all three Horizons, but new investors may want to focus on the first two: early diagnostics, AI in healthcare, life extension technologies in general, and therapies addressing age-related diseases. As for dealing with investment risks, it is really important to have access to the scientific and medical expertise in this field, because scientific due diligence is a key part of the investment decision-making.

You've recently set up the Longevity Vision Fund. How do you hope to differentiate it from others (Juvenescence has a strong focus on regenerative medicine, for instance)?

Longevity is such a new field for investment that there is room for everybody, which inspires collaboration and exchange of knowledge. As such, we don't tend to compete or actively differentiate ourselves from others in this field - ultimately, we are all in this together with the same goal of improving health and longevity for humanity. We also love what Juvenescence does in the field - especially their collaborations with the world's leading scientific hubs. Apart from Juvenescence, we also have other investments, including Life Biosciences and more - and we all share the same vision of extending healthy human lifespans and making the world a better place.

In your upcoming book you're set to cover the ethical 'trade-offs' of extended lifespans. What do you think could be the biggest benefit and the biggest detriment to us all living to 200?

I think the goal is not just to have "extended lifespans" or "to live to 200" (although this is my personal aspiration!) but the improved healthspan, the energy and the wellbeing that we could enjoy into the longer years of our lives. If we look from the perspective of healthy longevity, many detriments commonly associated with longer lifespans, such as an aging population, overburdening the economy, excessive medical costs become irrelevant. Extended healthy longevity means healthier populations, lower medical costs, a more productive workforce, a later retirement. In fact, as an investor, I consider longevity to be the biggest economic opportunity of the century.

Link: https://www.longevity.technology/forever-young-longevity-technology-with-sergey-young/

Targeting GAS1 to Put Muscle Stem Cells Back to Work in Old Tissues

A great many projects at various stages of development are characterized by their goal of forcing greater stem cell activity in old tissues, but without meaningfully addressing the underlying causes of stem cell decline in later life. This sort of research and development operates at the level of proximate causes, adjusting protein levels to change cell behavior. Among the potential therapies I'd place into this category: telomerase gene therapy; GDF11 upregulation; FGF2 inhibition; NAD+ upregulation; and so on. Muscle stem cells known as satellite cells are one of the better studied stem cell populations in this context, and many of the interventions are focused here. Today's open access research is a representative example, in that the authors describe a portion of the network of genes and proteins that control stem cell behavior, finding that it can be adjusted in order to force greater activity, overriding the normal reaction to an aged and damaged environment.

The loss of stem cell activity with age is thought to be an evolved response to rising levels of DNA damage, inflammation, and immune dysfunction that serves to reduce risk of early death by cancer, at the cost of a certain later decline into frailty. It is a part of the parcel of adjustments that lead our lengthy life spans in comparison to other similarly sized mammals. There has been, and still is, concern that putting cells back to work in this sort of way, without fixing the problems that lead to cancer, will raise cancer risk over the years following intervention. It will be slow and costly to understand whether or not this is the case in humans, but the evidence to date from animal studies show that these and analogous efforts result in far less cancer than might be expected. Perhaps this is due to improvement in immune function in those therapies, such as telomerase gene therapy, for which there is good data on cancer risk in animal models, but a firm answer on mechanisms is yet to arrive.

Possible therapeutic target for slow healing of aged muscles discovered

Skeletal muscles have a tremendous capacity to make new muscles from special muscle stem cells. These "blank" cells are not only good at making muscles but also at generating more of themselves, a process called self-renewal. But their amazing abilities diminish with age, resulting in poorer muscle regeneration from muscle trauma. A research team figured out that a protein called GAS1 is the culprit for this age-related decline.

The protein is found in only a small number of young muscle stem cells, but is present in all aged muscle stem cells, they discovered. Tinkering with muscle stem cells to express GAS1 in the entire young stem cell population resulted in diminished regeneration. By contrast, removing GAS1 from aged muscle stem cells rejuvenated them to a youthful state that supported robust regeneration. They also discovered that GAS1 inhibits another protein, a cell-surface receptor called RET, which they showed to be necessary for muscle stem cell renewal. The more GAS1 protein is present, the more RET's function is reduced. The inhibition of RET by GAS1 could be reversed by the third protein called GDNF, which binds to and activates RET. Indeed, when the researchers injected GDNF directly into the muscles of aged mice, muscle stem cell function and muscle regeneration were restored.

Muscle stem cell renewal suppressed by GAS1 can be reversed by GDNF in mice

Muscle undergoes progressive weakening and regenerative dysfunction with age due in part to the functional decline of skeletal muscle stem cells (MuSCs). MuSCs are heterogeneous, but whether their gene expression changes with age and the implication of such changes are unclear. Here we show that in mice, growth arrest-specific gene 1 (Gas1) is expressed in a small subset of young MuSCs, with its expression progressively increasing in larger fractions of MuSCs later in life. Overexpression of Gas1 in young MuSCs and inactivation of Gas1 in aged MuSCs support that Gas1 reduces the quiescence and self-renewal capacity of MuSCs. GAS1 reduces RET signalling, which is required for MuSC quiescence and self-renewal. Indeed, we show that the RET ligand, glial-cell-line-derived neurotrophic factor can counteract GAS1 by stimulating RET signalling and enhancing MuSC self-renewal and regeneration, thus improving muscle function. We propose that strategies aimed at targeting this pathway can be exploited to improve the regenerative decline of MuSCs.

Leptin as the Link Between Obesity and Hypertension

Hypertension, chronically raised blood pressure, is very damaging. It is an important mechanism by which low-level molecular damage and disarray in aging is converted into structural damage to important tissues in the brain, kidneys, and other organs. It is so influential in aging that lowering of raised blood pressure reduces mortality and disease risk even without addressing the underlying causes of the condition. Obesity is well known to cause raised blood pressure, and researchers here identify a novel mechanism for this effect involving leptin signaling. Since leptin signaling does change with age, it will be interesting to see whether or not this mechanism also operates to a significant degree in the aging and hypertension of non-obese individuals.

There's no question that as body weight increases, so too does blood pressure. Now, in a study of mice, researchers have revealed exactly which molecules are likely responsible for the link between obesity and blood pressure. Nearly a third of American adults have high blood pressure, and only about half of those people have their blood pressure under control through medications and lifestyle changes. Hypertension can be especially difficult to treat in obese patients.

The new work revolves around leptin, a molecule that controls appetite and metabolism in response to food. Obese people often become resistant to leptin, so rising levels of the molecule after a meal no longer boost metabolism or cause a feeling of fullness. In response to this resistance, leptin levels continue to rise with obesity. Leptin has also been shown to increase blood pressure and, surprisingly, obesity doesn't change that link - even when people are resistant to leptin's effects on metabolism and appetite, their blood pressure rises in response to the molecule. Until now, researchers weren't sure why.

Previous studies had revealed that there were high levels of leptin receptors in the carotid bodies - tiny clusters of cells along the carotid arteries on either side of the throat that respond to changing levels of oxygen and carbon dioxide in the blood. Researchers wondered whether this could be where leptin affects blood pressure, completely separate from its effects on appetite and metabolism in the brain.

Researchers first confirmed that giving high doses of leptin to lean mice triggered a rise in blood pressure of 10.5 to 12.2 mm Hg, while having no effect on heart rate or food intake. Then, they repeated the experiment in mice without functioning carotid bodies. This time, the animals' blood pressure didn't change in response to leptin. Next, the team studied obese mice that had no leptin receptors - despite their weight, they had normal blood pressure. But when the researchers injected the genes for leptin receptors directly into the carotid bodies of these mice, the animals' blood pressure readings rose by 9.4 to 12.5 mm Hg.

Link: https://www.hopkinsmedicine.org/news/newsroom/news-releases/researchers-discover-new-treatable-pathway-known-to-cause-hypertension-in-obese-people

A Profile of Tissue Engineering Efforts at LyGenesis

LyGenesis is the company founded to develop the technique of implanting organoid tissue into lymph nodes in order to allow it to survive and grow in the body. Some organs can carry out much or all of their function more or less regardless of location in the body, such as the liver and thymus. Thus any viable transplant strategy that leads to functional tissue thriving in the body should help patients. LyGenesis is initially focused on restoring liver function via this approach, but the thymus is next in line, with an eye to reversing some of the age-related decline in immune function.

Let's spend a little bit of time talking about your therapy. Let's say I hop into a time machine and go to the future, to whatever time it may be for it to have fully hit the market. What's your procedure going to look like?

So let's start with the present. Today, when a person needs a new liver, then a major transplantation surgery is their last option. This is an expensive and major operation - if you ever search online for "liver transplantation," you really do want to brace yourself. And then there's our approach, which uses endoscopic ultrasound to engraft cells into a patient's lymph nodes, and transforms the transplantation process into an outpatient procedure. That's one of the fundamental value propositions of our technology. The patient would be put under light sedation, the endoscope would be moved into a place where it can access your lymph nodes - the mesentery, in your abdominal region - and thirty minutes later you'd have multiple ectopic cell clusters placed there, engrafted by a cellular therapy, and you'd potentially even be able to leave the same day. Over the course of the next few weeks and months your lymph nodes would serve as bioreactors to grow multiple ectopic organs - a process called 'organogenesis' - that would begin filtering your blood and providing life-saving support. That's our vision of the future for our lead candidate in liver regeneration.

So the question that follows from that is: is this a therapy that would be a final procedure? Or is it a stopgap for those who are waiting on a transplant list for a full replacement?

One group of patients, for whom we hope this will be a single procedure and a curative therapy, are the many people with end stage liver disease. Those who have gradually and progressively lost liver function over time. Right now, once you get to a certain threshold where you've lost enough liver function, if you're healthy enough (and don't have any contraindicated medical comorbidities) you might make it onto the liver transplant list. Once you've made it on there you'll wait, oftentimes hundreds of days, or even longer, to receive an organ. And that's if you're lucky. So there's a huge unmet need. Patients need a new liver, but they're too ill and that prevents them from being eligible for a full organ transplantation. Right now there's no viable therapy for these people. So we think our therapy will be the first in line therapy for those patients.

How many lymph nodes, on average, would you need to use for this to work? Are there going to be any side effects from this process?

Right now, our best guess is that we will be grafting ectopic livers into, probably, three to five lymph nodes. You spread the mass of the ectopic organs across multiple lymph nodes, not just a single lymph node. That's our best guess and clinical development plan right now. In the research we've been doing for almost decade now, we've tried everything from a single lymph node to twenty lymph nodes or more, in the different animal models. And we've seen no adverse effects in terms of the transition from the lymph node to an ectopic organ. One thing we stress is that when you look at what happens over time, the lymph node disappears. The lymph node acts like a bioreactor in this process - once it's kicked the organ growth into gear, the organ takes over and the lymph node disappears. And because our bodies have hundreds of lymph nodes distributed throughout, we don't expect that losing a handful of them will produce any untoward effects.

How could this enhance people's longevity going forward?

Another great regenerative medicine story from our platform is based on our work on the thymus, which is fascinating. So, we have proof-of-concept data showing that we can regenerate the thymus ectopically inside the lymph nodes, as well. The thymus, as you may know, has a complicated biology; it does a lot of different things. But there is some indication that one of the effects of rebooting the thymus is to reboot the immune system - which absolutely could have regenerative, and therefore potential longevity, effects. We have try to be very careful about this, lots of things work in small animals that do not translate to people - there are jokes that the medical field has cured cancer in mice so many times over by now. We have to be careful when talking about longevity. Here's this dream of man since the beginning of time, to live longer. I think with some of the regenerative medicine and our understanding of biology we can start to make some inroads but, for what it's worth, I'm very careful not to promise that we're unlocking the fountain of youth. That's not the case. We're trying to develop science-based, FDA-regulated therapies to address unmet medical needs - even though, admittedly, the famous one would be potential downstream effects on aging and longevity.

Link: https://www.longevity.technology/exclusive-profile-lygenesis-and-growing-ectopic-organs/

A Deeper Delve into the Mechanisms of Thymic Atrophy

The faltering quality of the immune system in later life is driven by several quite different factors, but the one that is perhaps most evident in the immune declines of middle age is the atrophy of the thymus. The thymus is a small organ located under the sternum and over the heart; it is where thymocytes produced in the bone marrow mature into T cells. As ever more of the active tissue of the thymus is replaced with fat, the ongoing supply of new T cells diminishes. The adaptive immune system becomes ever more a closed system and its cells become ever more dysfunctional: exhausted, senescent, misconfigured and overly focused on persistent viral infections such as cytomegalovirus, lacking the ability to respond to new threats. Thus older people have increased cancer risk, increased senescent cell burden, and reduced ability to defend themselves against infectious pathogens. This is why a number of research groups and biotech startups, including the company that I cofounded with Bill Cherman, Repair Biotechnologies, are working on ways to regenerate the thymus.

Why does the thymus atrophy? There are at least two stages. Initially thymic involution takes place in early life. By the end of teenage years, the thymus is much reduced from childhood. This is a developmental program. Afterwards, however, different mechanisms take over: evidence strongly suggests chronic inflammation to play an important role in reducing the ability of thymic progenitor cells to sustain thymic tissue. This may or may not be linked to cellular senescence. Senescent cells are highly inflammatory, but it seems unlikely that cellular senescence plays an important role prior to middle age. The senescent cell burden is thought to be very low up until that time - since the immune system plays an important role in culling senescent cells, it isn't until the immune system starts to decline in earnest that senescent cells really begin to play a significant role in aging. So the slow decline of the thymus from early adulthood to early middle age is more of a question mark, while for later declines we can point to the usual culprit of significantly increased inflammation and presence of senescent cells. There are no doubt other mechanisms at work as well, of course.

In this open access paper, researchers delve more deeply into the atrophy of the thymus and its regrowth via the mechanism of sex steroid ablation. They provide evidence for this to involve existing cells expanding their structure rather than generation of new thymic cells, at least for this method of thymic regrowth. It makes for interesting reading in the context noted above; it is worth thinking about the various processes noted here in relation to chronic inflammation. It is perhaps more interesting as a reminder that sex steroid ablation in mice has been shown by other research groups to only produce transient regrowth of the thymus (it is unclear as to whether this is also the case in humans, as long term data is lacking), and that this regrowth doesn't reproduce the youthful structure of the thymus, even while it certainly seems to boost the output of T cells.

Dynamic changes in epithelial cell morphology control thymic organ size during atrophy and regeneration

Since T cells must be continuously produced throughout life, the accelerated atrophy of the thymus with age is enigmatic, especially given its latent regenerative potential. Age-associated atrophy is common to many tissues (for instance, muscle, central nervous system, skin, and testes), and can be a consequence of cell loss (death), but often is associated with the shrinkage (atrophy) of individual cells, collectively resulting in tissue atrophy. Likewise, regeneration may be attributed to proliferation of stem or end stage cells (hyperplasia), but can also result from growth of existing cells (hypertrophy) that is independent of proliferation. Despite the magnitude of atrophy and regeneration in the thymus, the underlying mechanisms for these processes have remained obscure, although our previous findings show that both are attributable to changes in cortical thymic epithelial cells (cTEC). Our non-presumptive analysis of global gene expression in young cTEC, aged cTEC, or aged cTEC in the regenerating thymus suggested that genes associated with cell size and shape dominated the dynamic landscape. However, the size and shape of individual cTEC has been difficult to discern using conventional methods, thus obscuring any changes that might occur during age atrophy or regeneration.

In other tissues, epithelial cells exhibit distinctive morphologies, and are polarized (with respect to a basement membrane) in either a single simple layer or in multiple stratified layers. In the thymus, with the exception of a small proportion of conventional epithelial cells lining the capsule and blood vessels, most TEC lack classical epithelial morphology. Instead, they are defined as epithelial mainly based on biochemical features, such as the appearance of desmosomes or keratin filaments. Various histochemical markers indicate that cTEC, in particular, form an extensive network of finely branched cell processes, but the morphology and number of individual cells in this network has been very difficult to define, due to this elaborate branching morphology and their relatively uniform staining with various antibody markers. Medullary thymic epithelial cells (mTEC) appear to be less dense, and therefore more easily defined as individual cells, but extensive heterogeneity among lineage markers has rendered the morphology of individual mTEC vague as well. Consequently, defining the size, shape, and interconnectivity of these essential cells has remained enigmatic.

Given the need for continuous T cell production during life, the thymus is paradoxically the most rapidly aging tissue in the body. It reaches peak tissue mass (in all species studied) prior to the onset of adolescence, and exhibits rapid and progressive atrophy afterwards, such that by mid-life most healthy mass is lost. Except at very late age, thymic lymphocytes are essentially unchanged in the atrophied thymus, while these age related changes are primarily manifest in stromal cells, particularly cortical. Niche availability provided by cTEC is the rate limiting feature for lymphoid cellularity and thymus size. Thus, as cTEC deteriorate during aging, the thymus becomes proportionally smaller. Since new T cells are produced proportionally to thymic mass, peripheral homeostasis thus becomes more dependent on homeostatic expansion of existing T cells, with the repertoire gradually drifting towards immunologic memory, with diminished broad spectrum immunity as a result.

Remarkably, the atrophied thymus retains potent regenerative capacity, and can be induced to attain its full peak size by stimuli such as androgen ablation. Quite logically, albeit without much evidence, thymic atrophy is assumed to result from senescence-associated cell death among TEC, while regeneration is believed to result from proliferative expansion from an epithelial stem cell or progenitor cell population. Consistent with these concepts, experimental loss of cTEC does result in decreased thymus size, while induction of cTEC proliferation results in a larger thymus. However, the fact that thymus size changes in response to TEC number (and resulting lymphoid capacity) does not mean that atrophy or regeneration, under physiologic conditions, necessarily involve changes in TEC number.

The present study stems from a large temporal database of stromal transcriptional profiles during aging and regeneration. Non-presumptive analysis indicates that dynamic changes in genes associated with cell size and cell morphology dominated the regeneration response. Here we use two different medullary stroma may play an important role in modulation of cTEC morphology via paracrine production of known morphogens and growth factors. Our findings reconcile diverse existing concepts, and provide a revised view of atrophy and regeneration based on structural remodeling of a novel cTEC morphology that is unique among metazoan tissues.

Upregulation of Nrf2 Slows Progession of Intervertebral Disc Degeneration

Researchers here make an interesting observation relating to the function of the nucleus pulposus cell population critical to the progression of intervertebral disc degeneration. They provide evidence suggesting that upregulation of Nrf2 can slow progression of the condition by making these cells more resilient to stress, preventing cell death and cellular senescence and consequent fibrosis, and thus reducing the pace of tissue degeneration due to cell loss or dysfunction.

A normal intervertebral disc (IVD) consists of an outer annulus fibrosus (AF) that forms a ring structure to enclose the central nucleus pulposus (NP) and is connected to adjacent vertebral bodies by the cartilaginous endplates. The NP is crucial to maintain biomechanical function of IVD by counteracting and dissipating compressive loads, which depends on the extracellular matrix (ECM) secreted by nucleus pulposus cells (NPCs). However, the NP changes from a gel-like substance into a fibrous tissue with age, resulting in the structural and functional failure of IVD. Although the molecular mechanism of these pathological changes has not been fully understood, the apoptosis and senescence of NPCs are proven to be crucial to the development of intervertebral disc degeneration (IDD).

At present, increasing studies have demonstrated that reactive oxygen species (ROS) is closely related to the apoptosis and senescence of NPCs, contributing to the initiation and progression of IDD. As the main site of intracellular ROS generation, mitochondrion is also adversely influenced by ROS. Mitochondrial dysfunction is regarded as an important factor in NPC apoptosis and senescence, and accelerates disc degeneration. Thus, the strategies that aim at antioxidation and maintenance of mitochondrial homeostasis are promising to prevent or retard IDD.

Here we present evidence that a lower level of Nrf2 is closely associated with higher grade of IDD. The apoptosis and senescence of nucleus pulposus cells (NPCs) were exacerbated by Nrf2 knockdown, but suppressed by Nrf2 overexpression under oxidative stress. Based on findings that Kinsenoside could exert multiple pharmacological effects, we found that Kinsenoside rescued the NPC viability under oxidative stress and protected against apoptosis, senescence, and mitochondrial dysfunction in a Nrf2-dependent way. Further experiments revealed that Kinsenoside activated a signaling pathway of AKT-ERK1/2-Nrf2 in NPCs. Moreover, in vivo study showed that Kinsenoside ameliorated IDD in a puncture-induced model. Together, the present work suggests that Nrf2 is involved in the pathogenesis of IDD and shows the protective effects as well as the underlying mechanism of Kinsenoside on Nrf2 activation in NPCs.

Link: https://doi.org/10.18632/aging.102302

Reviewing AGEs and ALEs in Oxidative Stress and Aging

Advanced glycation end products (AGEs) and the less discussed advanced lipoxidation end products (ALEs) are an interesting topic in the context of aging. There are in fact two distinct topics here. The first is the presence of persistent cross-links, in which glucosepane AGEs form links between extracellular matrix molecular, degrading the structural properties of tissue, particularly elasticity. These cross-links, arising from the normal operation of metabolism, are resilient and not broken down by our biochemistry. Some form of biotechnology, such as therapies based on enzymes mined from bacterial species that can metabolize glucosepane, will be required to remove their contribution to the aging process.

The second topic is that a menagerie of many different short-lived AGEs and ALEs emerge in greater numbers in the aged or diabetic metabolism, and cause chronic inflammation via their interaction with the receptor for AGEs, RAGE. They also produce other significant changes for the worse in cellular behavior. There is also some debate over whether or not AGEs and ALEs in the diet are important in these processes, with evidence for either answer to that question. It isn't clear as to what might be the best approach to this side of the problem, but researchers are considering targeting RAGE as a single influential point of intervention.

Oxidative stress is a consequence of the use of oxygen in aerobic respiration by living organisms and is denoted as a persistent condition of an imbalance between the generation of reactive oxygen species (ROS) and the ability of the endogenous antioxidant system (AOS) to detoxify them. The oxidative stress theory has been confirmed in many animal studies, which demonstrated that the maintenance of cellular homeostasis and biomolecular stability and integrity is crucial for cellular longevity and successful aging.

Mitochondrial dysfunction, impaired protein homeostasis (proteostasis) network, alteration in the activities of transcription factors such as Nrf2 and NF-κB, and disturbances in the protein quality control machinery that includes molecular chaperones, ubiquitin-proteasome system (UPS), and autophagy/lysosome pathway have been observed during aging and age-related chronic diseases. The accumulation of ROS under oxidative stress conditions results in the induction of lipid peroxidation and glycoxidation reactions, which leads to the elevated endogenous production of reactive aldehydes and their derivativesm, giving rise to advanced lipoxidation and glycation end products (ALEs and AGEs, respectively).

Both ALEs and AGEs play key roles in cellular response to oxidative stress stimuli through the regulation of a variety of cell signaling pathways. However, elevated ALE and AGE production leads to protein cross-linking and aggregation resulting in an alteration in cell signaling and functioning which causes cell damage and death. This is implicated in aging and various age-related chronic pathologies such as inflammation, neurodegenerative diseases, atherosclerosis, and vascular complications of diabetes mellitus. In the present review, we discuss experimental data evidencing the impairment in cellular functions caused by AGE/ALE accumulation under oxidative stress conditions. We focused on the implications of ALEs/AGEs in aging and age-related diseases to demonstrate that the identification of cellular dysfunctions involved in disease initiation and progression can serve as a basis for the discovery of relevant therapeutic agents.

Link: https://doi.org/10.1155/2019/3085756

Help to Crowdfund the SENS Research Foundation Transgenic Mouse Project to Move a Mitochondrial Gene into the Cell Nucleus

The SENS Research Foundation science team is taking the next step in their work on moving mitochondrial genes into the cell nucleus, a process called allotopic expression. Having proven that they can carry out this task with the ATP8 gene in cells, they are now aiming at proof of principle in mice. This will require the production of transgenic mice, using a novel technology funded by the SENS Research Foundation called the maximally modifiable mouse. This mitochondrial project is being crowdfunded at Lifespan.io: you, I, and everyone else can contribute to advancing the state of the art one step further towards eliminating mitochondrial DNA damage as a cause of aging.

Mitochondria are the power plants of the cell, a herd of organelles descended from ancient symbiotic bacteria. They reproduce by replication and are recycled when damaged by cellular maintenance processes. Mitochondria carry the remnant of the original bacterial DNA, encoding thirteen genes vital to the process by which mitochondria package chemical energy store molecules. Unfortunately mitochondria generate reactive molecules as a byproduct of their operation, and this DNA is less well protected than the DNA of the cell nucleus. Some forms of damage to this DNA can break mitochondrial function in ways that allow the broken mitochondria to outcompete their functional peers, leading to dysfunctional cells that export massive quantities of damaging, oxidative molecules into the surrounding tissue. This contributes to conditions such as atherosclerosis, via the production of significant amounts of oxidized cholesterol in the body.

Allotopic expression of mitochondrial genes will work around this issue by providing a backup source of the proteins necessary to mitochondrial function. It has been demonstrated to work for ND4, and that project has been running for some years at Gensight Biologics to produce a therapy for inherited conditions that involve mutation of that gene. This work must expand, however, to encompass all thirteen genes of interest. So lend a hand, and help the SENS Research Foundation team take the next step forward in this process.

MitoMouse: SENS Transgenic Mouse Project

The SENS Research Foundation (SRF) has formulated seven practical repair strategies to the common drivers of aging. Whereas some of these strategies are now widely researched by the scientific establishment the MitoSENS strategy for dealing with mitochondrial damage is among the most novel. Our theory is, through allotopic expression, that is by placing functional copies of critical mitochondrial DNA (mtDNA) genes in the nucleus of the cell one could alleviate defects arising due to mutations in mtDNA.

When it was proposed, this unique and ambitious strategy was perhaps too daring for mainstream labs and funding agencies to contemplate. Consequently, the MitoSENS approach has been an in house project for SENS that would not have been possible without community support. So far, this community-funded approach has an excellent track record leading to groundbreaking discoveries. In 2013 SENS organized its first crowdfunding campaign specific to MitoSENS in partnership with LongeCity. The small initiative seeded significant research momentum and paved the way for a larger fundraiser in 2015 at Lifespan.io. Breakthrough discoveries followed and a proof-of-principle for the MitoSENS approach was established for the first time in human cells. Here, the MitoSENS team in collaboration with scientists from the Buck Institute showed that allotopic expression of two mtDNA genes could bring back several functions in a patient cell line with a severe mutation in one of the mtDNA genes, namely ATP8.

To move this strategic advancement toward the clinic, SRF then created the "maximally modifiable mouse model". This mouse has a unique modification in their nuclear genome to allow a targeted insertion of new genes at a specific location. Using this mouse, we are ready to take the next step and pursue mitochondrial gene therapy in an animal model.

Mice of the C57/BL6MT-FVB strain (let's call them "SickMice") have a mitochondrial gene defect, a mutation in the mitochondrial ATP8 gene, and exhibit several age-related symptoms including lower fertility, arthritis, type II diabetes, and neurological impairments. Since mitochondria are only inherited from the mother, cross-breeding female SickMice with male mice from other models will result in the same mitochondrial dysfunction.

We will use the maximally modifiable model to create a new transgenic mouse (the "allotopic ATP8 transgenic mouse - Mitomouse"). This mouse will have the ATP8 gene that is important for mitochondrial function hidden in the cell nucleus and thus capable of being passed on to offspring irrespective of gender. Our hypothesis is that both male and female offspring from SickMice x MitoMice will result in rescued mitochondrial function. This would prove the viability of the MitoSENS strategy by showing that functional backup copies of mitochondrial DNA genes in the nucleus can replace their mutated counterparts in live animals.

Mitochondria as a Form of Intracellular Signaling Important in the Aging Brain

Researchers in the field of neurodegeneration here provide evidence for supporting cells in the brain, specifically microglia, to use their own mitochondria as a form of signaling. Mitochondria are the power plants of the cell, responsible for packaging chemical energy store molecules. Their function declines with age for a range of poorly understood reasons, and this is important in numerous age-related conditions, particularly those in energy hungry tissues such as the brain. The researchers here report that microglia eject both whole and fragmentary mitochondria that other cells react to. Where the microglia are stressed, these ejected mitochondria are more often fragmentary, and are harmful to the surrounding environment.

This is all quite fascinating, given (a) past work on the ability of cells to take up mitochondria from their surroundings or pass mitochondria between one another, and (b) the growing body of evidence showing that senescent microglia are important in the progression of numerous age-related neurodegenerative conditions. Senescent cells, of course, cause harm to their surroundings via active signaling, consisting of secreted molecules and extracellular vesicles - and perhaps also mitochondria.

Researchers report that when microglia spat out damaged mitochondria, these cast-offs inflamed astrocytes, which in turn expelled their own mitochondrial fragments. Jetsam from either cell sickened neurons as well, limiting their energy production. Conversely, an inhibitor of mitochondrial fission protected astrocytes and neurons from the effect of externally added mitochondrial fragments, suggesting that mitochondrial fragmentation cascades from cell to cell. Curiously, adding whole, functional mitochondria to neuronal cultures mitigated the damage from fragmented organelles. Mitochondria are ancient bacterial invaders of eukaryotic cells, but are tolerated by the body because they are sequestered inside cells. Once released, their proteins and other macromolecules may trigger inflammation.

In mouse models of neurodegenerative conditions, P110 improved survival and motor skills. Exactly how P110 protected neurons in these mouse models was unclear. Researchers added the inhibitor to microglia expressing a 73-amino-acid polyglutamine expansion (Q73) that causes mitochondria to malfunction and fragment. P110 treatment reduced mitochondrial fission, boosted ATP production, and lowered reactive oxygen species. How might microglia in these models affect other cell types? The authors added media from Q73 microglia to mouse primary astrocyte cultures. In response, the astrocytes pumped out TNF-α and IL-1β. Their mitochondria became dysfunctional and fragmented, and 75 percent more astrocytes died. Adding P110 directly to astrocytes also protected them from the Q73 microglia-conditioned media.

Taken together, the data implied that fragmentation of mitochondria causes microglia and astrocytes to release factors that can somehow damage mitochondria in other cell types. The authors wondered if those released "factors" might be mitochondria themselves. Confirming this, the authors found intact functional mitochondria in media from healthy microglial cultures. Media from Q73 microglia cultures contained the same total number of mitochondria as media from the healthy cultures, but only half as many were whole and functional. At the same time, the amount of free-floating mitochondrial proteins in Q73 culture medium rose, suggesting the organelles were leaking contents. Treating Q73 microglial cultures with P110 bumped the number of functional mitochondria almost back to that of control cultures.

While the damaged organelles may trigger inflammation by activating microglia or astroglia, their direct effect on neurons remains puzzling, as does the effect of whole mitochondria. Researchers are investigating the idea that neurons take up whole or fragmented organelles, with the former bolstering cellular respiration and the latter spreading damage.

Link: https://www.alzforum.org/news/research-news/mitochondrial-jetsam-spurs-neurodegeneration

Age-Related Changes in Insulin Signaling in the Development of Sarcopenia

Insulin signaling and IGF-1 is one of the more intensely studied portions of biochemistry, in mammals and lower animals, when it comes to the interaction between metabolism and pace of aging. Researchers here look at how changes in this signaling might contribute to sarcopenia, the age-related loss of muscle mass and strength. Sarcopenia is a condition with many, many contributing factors, and it is important to think about the chains of cause and effect when reading about them. Different processes operate upstream or downstream of one another, but nonetheless tend to be studied in isolation of the bigger picture. There are first causes and downstream, proximate causes, and changes in insulin signaling have the look of being a fair way downstream of the root causes of aging.

Sarcopenia is defined as the combined loss of skeletal muscle strength, function, and/or mass with aging. This degenerative loss of muscle mass is associated with poor quality of life and early mortality in humans. The loss of muscle mass occurs due to acute changes in daily muscle net protein balance (NPB). It is generally believed a poor NPB occurs due to reduced muscle protein synthetic responses to exercise, dietary amino acid availability, or an insensitivity of insulin to suppress breakdown. Hence, aging muscles appear to be resistant to the anabolic action of exercise and protein (amino acids or hormonal) when compared to their younger counterparts.

The mechanisms that underpin anabolic resistance to anabolic stimuli (protein and resistance exercise) are multifactorial and may be partly driven by poor lifestyle choices (increased sedentary time and reduced dietary protein intake) as well as an inherent dysregulated mechanism in old muscles irrespective of the environmental stimuli. The insulin like growth factor 1 (IGF-1), Akt/Protein Kinase B and mechanistic target of rapamycin (mTOR) pathway is the primary driver between mechanical contraction and protein synthesis and may be a site of dysregulation between old and younger people.

Therefore, our review aims to describe and summarize the differences seen in older muscle in this pathway in response to resistance exercise (RE) and describe approaches that researchers have sought out to maximize the response in muscle. Furthermore, this review will present the hypothesis that inositol hexakisphosphate kinase 1 (IP6K1) may be implicated in IGF-1 signaling and thus sarcopenia, based on recent evidence that IGF-1 and insulin share some intracellular bound signaling events and that IP6K1 has been implicated in skeletal muscle insulin resistance.

Link: https://doi.org/10.3389/fnut.2019.00146

Towards a More Glial-Centric View of Alzheimer's Disease

The progression of Alzheimer's disease is very complicated, and yet to be fully understood, for all that there is a good catalog of the individual pathological mechanisms involved as the condition progresses: aggregation of amyloid-β and tau; persistent viral infection; chronic inflammation; dysfunction in the immune cells of the brain; and more. The question is how these mechanisms fit together into chains of cause and effect, a process of discovery that is complicated by the fact that order of progression or importance of specific mechanisms may be quite different between individuals, and some mechanisms have two-way relationships, in which either is capable of aggravating the other.

Is Alzheimer's disease a condition in which various factors cause amyloid-β deposition over the years, which causes glial cells in the brain to become dysfunctional and inflammatory, which leads to formation of the toxic tau protein aggregates known as neurofibrillary tangles and consequent cell death? Or is Alzheimer's disease due to the age-related disarray of glial cells, that in turn leads initially to amyloid-β pathology, and then later to tau pathology as the state of disarray worsens? There is good evidence to support either position. That clearing amyloid-β from the brain has failed persistently to improve patients is a strike against the amyloid-β as first cause arguments, but equally it may be that these efforts have taken place at too late a stage in the progression of Alzheimer's disease, long after it would have been effective.

Microglia in Alzheimer Disease: Well-Known Targets and New Opportunities

Microglia cells are the main immunocompetent cells in the brain. They colonize the brain in the early prenatal period, but contrary to other tissue resident macrophages, they remain secluded within the central nervous system (CNS) throughout life and self-renew at slow pace. Should the brain homeostasis be compromised, microglia change their phenotype and initiate a defense program. Thus, under pathological conditions, they adopt reactive states characterized by multiple morphological and functional changes including but not limited to increased phagocytosis and increased expression of receptors, cytokines, chemokines, and additional inflammation related molecules.

Alzheimer's disease (AD) classical hallmarks include brain atrophy, extracellular amyloid-beta (Aβ) deposits, intracellular aggregated phosphorylated tau, dystrophic neurites, synapses, and neurons loss. The presence of reactive glial cells within the neuritic plaques was described by Alois Alzheimer himself and further studies identified both reactive astrocytes and microglia in the vicinity of the Aβ deposits. Long considered as a consequence of the pathology, reactive glia and associated neuroinflammation are now regarded as playing key roles in both disease initiation and progression. Evidence strongly supports a causal involvement of microglial cells in AD pathogenesis and generated a strong interest for studying these cells. Yet, the roles of microglia in AD initiation and progression are unclear and heavily debated, with conflicting reports regarding their detrimental or protective contribution to the disease.

The involvement of microglia in AD is a relatively new area of research, but it is growing at a fast pace. Recent genome-wide association studies have established that the majority of AD risk loci are found in or near genes that are highly and sometimes uniquely expressed in microglia. This leads to the concept of microglia being critically involved in the early steps of the disease and identified them as important potential therapeutic targets.

Over the recent years, several technological breakthroughs have been achieved, allowing scientists to address new challenging questions. These technical developments now allow studying microglia roles with medium or high throughput workflows, and perform fine analysis of their functions in preserved environments. A better understanding of the contribution of microglia cells to AD initiation and progression is expected to renew the interest of big pharma to re-invest in the field and will pave the way toward better designed strategies.

NRF2 and Age-Related Impairment of Endothelial Tissue Maintenance

Researchers here examine a proximate cause of age-related dysfunction in a progenitor cell population responsible for tissue maintenance of the endothelium of blood vessels. Declining blood vessel function and integrity is an important part of aging, with many contributing causes, and there is considerable interest in the research community when it comes to identifying ways to restore these losses. As is the case here, however, most researchers focus on possible adjustments to the age-distorted state of cellular metabolism, meaning raising or lowering specific protein levels in order to override cell behavior to some degree, rather than looking to repair the deeper causes of that age-distorted state. I, and others, think that this focus on proximate causes rather than root causes is a poor strategy, doomed to marginal results and slow progress.

Cardiovascular disease (CVD) remains the leading cause of death in the elderly, and treatment is costly. The reduced endothelial function with aging contributes to the development of CVD, so maintaining the normal endothelial integrity is an important therapeutic approach to reduce the age-related risk of CVD. Endothelial progenitor cells (EPCs) are thought to promote postnatal neovascularization and maintain endothelial integrity and function. These cells have aroused the interest of researchers, especially given the limited regenerative capacity of mature endothelial cells. It has been suggested that EPCs not only foster the continuous recovery of the endothelium after injury/damage, but also stimulate angiogenesis.

The function and number of circulating EPCs decreases with aging. Aging impairs the ability of EPCs to regenerate and migrate to damaged blood vessels and ischemic areas to repair the vasculature and promote angiogenesis. Aging EPCs exhibit reduced capacities. Therefore, therapeutic interventions that stimulate EPCs to enhance endothelial repair in elderly individuals have important clinical implications for the aging population. Different mechanisms of EPC senescence have been reported, including telomere shortening, age-related declines in pro-angiogenic factors, increased oxidative stress, reduced nitric oxide (NO) bioavailability and chronic low-grade inflammation. However, the complex molecular network responsible for EPC senescence requires further investigation.

We explored the effects of nuclear factor (erythroid-derived 2)-like 2 (NRF2) on EPC activity during aging. Both in vitro and in vivo, the biological functioning of EPCs decreased with aging. The expression of NRF2 and its target genes also declined with aging, while Nod-like receptor protein 3 (NLRP3) expression increased. Aging was associated with oxidative stress, as evidenced by increased reactive oxygen species and malondialdehyde levels and reduced superoxide dismutase activity. Nrf2 silencing impaired the functioning of EPCs and induced oxidative stress in EPCs from young mice. On the other hand, NRF2 activation in EPCs from aged mice protected these cells against oxidative stress, ameliorated their biological dysfunction and downregulated the NLRP3 inflammasome. These findings suggest NRF2 can prevent the functional damage of EPCs and downregulate the NLRP3 inflammasome through NF-κB signaling.

Link: https://doi.org/10.18632/aging.102234

Arguing that People are Emotionally Fragile, and thus Should be Prevented from Using Metrics that Correlate with Age

I have never liked the class of argument, often presented whenever new biomarkers are close to realization, that suggests people should be prevented from using them because they are emotionally fragile and cannot handle the information responsibly. Ignorance wielded as shield, a sentiment that should be - but isn't - deeply offensive to all in this era of information and communication. This argument has been voiced for biomarkers for conditions without viable therapies, such as Alzheimer's disease. Here it is voiced for biomarkers of aging, a field in which there exist rejuvenation therapies, senolytics, with ample animal evidence, but that are not yet conclusively proven to produce rejuvenation in published human trials.

To me, this eagerness to forbid seems little more than control for the sake of control, a sadly widespread state of affairs in the heavily regulated medical field. There are any number of people willing to argue that medical technologies and medical information should be even more locked away behind walls and rules, even harder to obtain and use, than is presently the case. Those arguing inevitably count themselves among the enlightened few, defending the benighted and the ignorant masses from their own self-sabotaging ways. This is a form of dehumanization of the other, and it is a part of the road to truly unpleasant end stages for regional governance, as well illustrated over the course of the past century or so.

Over the past several years, scientists have identified four genetic and molecular biomarkers that potentially predict human and animal longevity. The first is the rate at which an individual's telomeres shorten in length. There is increasing evidence from both human and animal studies that the slower the rate of telomere shortening, the longer that individual is likely to live. The second is the rate of gene methylation, indicating an increased level of methylation was correlated with shortened longevity. The third is the polygenic risk. A recently reported genetic analysis can identify "10 percent of people with the most protective genes, who will live an average of five years longer than the least protected 10 percent," according to a statement from a scientist who developed the method.

The fourth approach was described in a study this year that identified 14 blood-based biomarkers of metabolism that when combined into a predictive score was statistically associated with predicting the end of life. Screening individuals using these metabolite profiles appeared to be predictive of a high risk of mortality within 10 years. In this study, scientists included more 44,000 people from 12 cohorts who were followed between three and 17 years to establish a correlation with these blood metabolites and longevity. There are no comparable studies that have examined such a large population using telomere length or gene methylation as longevity predictors.

Each of the four approaches to predicting longevity raises several scientific and ethical concerns that need to be addressed. The blood-based biomarker studies differ from current clinical end-of-life predictors, such as blood pressure and cholesterol levels, because there are established behavioral and drug interventions to reduce blood pressure and cholesterol levels. Were biomarkers to be developed for clinical applications, we propose that they should only be used if they provide actionable results. We should be cautious in applying both premature and unproven longevity results in a clinical situation that has such serious implications.

Several companies are already offering consumers tests to assay their telomere length. We would not be surprised if in the future companies will use other biological or genetic predictors to assess human longevity or offer ways to reverse our biological clocks. We also caution consumers against seeking out such longevity predictions should they be offered direct to the public, unless companies present the results to the consumer by a certified genetic counselor, as the psychological effect from these data could be devastating. Furthermore, the unintended consequences of using end-of-life predictions based on these preliminary studies can be unsettling. Do we want our life insurance agents canceling any policy or raising rates based on our biomarkers? In conclusion, we have not reached the point when it is ethical and scientifically valid to use biomarkers to predict longevity.

Like: https://www.the-scientist.com/news-opinion/opinion--biomarkers-of-longevity-not-ready-for-the-clinic--66497