Recent Research on Modulating Muscle Stem Cell Decline with Aging

Today I'll point out a couple of recent papers that are illustrative of present research into muscle stem cells and the changes that take place in these cell populations with age. Note the interest in finding ways to modulate those changes, slow them down, or somewhat reverse them. Muscle stem cells are one of the most studied of stem cell populations, a state of affairs that is partly historical accident and partly because it is easier to obtain cells to work with that is the case for many other tissues. There are hundreds of cell types in the body, and every different form of tissue is supported by its own populations of stem cells and progenitor cells at various stages of differentiation. They are all very different, requiring different signals and circumstances in order to function correctly, as is illustrated by the fact that researchers need to develop new methodologies to work with each new tissue type that is built from cells in the laboratory. Understanding muscle stem cells is just one step on a lengthy road leading towards a complete catalog of the cellular biochemistry of tissue maintenance and regeneration.

All of our tissues are almost entirely composed of somatic cells with limited replicative lifespans. Once they reach the Hayflick limit, they self-destruct or become senescent, and most of the latter are destroyed by the immune system. Stem cells and progenitor cell populations are less limited but more tightly regulated, spending much of their time dormant. When active they work to create a supply of new somatic cells to replace those lost over time. This system in which near all cells are very limited in growth potential came into being because it enables multicellular organisms to have a low enough rate of cancer to prosper in the evolutionary competition for survival. Cancer and regeneration have always been the opposing sides of the same coin for higher species characterized by important, delicate structures that must be maintained intact over time. Exceptional regeneration of the sort possessed by hydras, a species that appears to be functionally immortal, gets left behind somewhere before the evolution of a sophisticated central nervous system: it may well be that those two characteristics are mutually exclusive. Still, we mammals got a raw deal in comparison to zebrafish or salamanders, capable of regenerating limbs. At some point it was more favorable in the evolutionary arms race to drop regeneration in favor of additional resistance to cancer.

One of the most pressing aspects of stem cell biology is that the activity of stem cell populations decline with age, something that so far appears to be largely a matter of signaling when it comes to muscle stem cells. That may or may not universally true for other types of stem and progenitor cell. Certainly stem cell populations and their supporting niche cells suffer the molecular damage of aging just like other cells do. Nonetheless, in the case of muscle stem cells there are numerous studies demonstrating restored stem cell activity in old animals via various forms of intervention. Thus there is considerable interest in the research community when it comes to building a map of the biochemistry of this stem cell decline, and then building therapies to put these stem cells back to work. Loss of muscle mass and strength, and ability to regenerate from injury, is an important component of age-related frailty. If that can be reduced by overriding the reactions of cells to rising levels of damage, and without significantly raising the risk of cancer, then perhaps some good can be done here even in advance of methods of repairing the underlying damage that causes aging. I'd much rather see more work on rejuvenation through repair rather than forcing damaged cells into youthful patterns of behavior, but the latter is clearly going to happen regardless of my opinions on the matter: a fair number of research teams are headed in that direction. Stem cell research as a whole is set on a collision course with the issue of stem cell decline in aging, as a sizable majority of the therapies one would want to want to build using stem cell research are for age-related conditions. Solving the issues of failing stem cells in an old tissue environment must happen at some point in order for researchers to achieve their goals.

Muscle PGC-1α modulates satellite cell number and proliferation by remodeling the stem cell niche

Satellite cells (SC) are adult muscle stem cells located at the periphery of muscle fibers. SCs are accordingly exposed to various signals from within and outside of the fiber, which collectively comprise the specific environment termed the SC niche. Although metabolically inactive and quiescent in resting conditions, SCs quickly become activated in response to a stimulus such as injury or strenuous exercise. These stem cells are indispensable for skeletal muscle regeneration, and despite being present in relatively small numbers (2-5% of total myonuclei), SCs have a vast proliferative and regenerative potential. Proper activation and proliferation, as well as return to quiescence, are all essential to preserving SC number and function. In various pathological contexts, for example, in certain muscular dystrophies or aging, a depletion of SC numbers is linked to impaired regenerative capacity. Importantly, reduced SC numbers and myogenic activity are often caused by alterations of the SC niche. For example, excess fibronectin in the basal lamina in an uninjured state is correlated with a reduced ability of SCs to respond to injury. Age-associated accumulation of extracellular matrix (ECM) components leads to the thickening of the basal lamina, thereby preventing SCs from sensing changes in the environment and resulting in a reduced activation propensity. Inversely, treatment with fibronectin can restore satellite cell activation in old muscle. Moreover, local transient fibronectin secretion by SCs is an important step in the cascade of SC activation and subsequent proliferation, and such a transient increase in fibronectin muscle expression is necessary for successful regeneration.

SC numbers vary by muscle fiber type, with higher counts present in oxidative compared to glycolytic muscle beds. In line with this, endurance exercise increases SC numbers in mice and humans. The peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) is a major driver of oxidative fiber-type specification, mitochondrial biogenesis, and high endurance capacity. Furthermore, PGC-1α gene expression is induced by exercise and exhibits a preference for slow, oxidative fibers. Finally, muscle-specific overexpression of PGC-1α protects against a variety of muscle-wasting conditions, including fiber atrophy or the pathologies in dystrophic mouse models. Nevertheless, a potential link between PGC-1α, oxidative fibers, exercise, and SCs has not been studied yet. By using a mouse model which specifically overexpresses PGC-1α in adult muscle fibers, we attempted to delineate the aforementioned missing link and assess the importance of indirect effects of PGC-1α on SC phenotype. Here, we show that muscle fiber PGC-1α modulates SC number as well as proliferation and that the latter, at least in part, could be regulated by the altered expression of ECM components, including fibronectin protein levels, in the basal lamina. Increased PGC-1α content in the SC niche therefore results in an accelerated SC response to injury and higher myogenic capacity.

Loss of niche-satellite cell interactions in syndecan-3 null mice alters muscle progenitor cell homeostasis improving muscle regeneration

During aging, myofiber size progressively decreases with an accompanying loss of fast twitch myofibers, leading to reduced overall muscle mass and strength that, when severe, results in sarcopenia. Loss of muscle mass and strength is accompanied by increased matrix deposition (fibrosis) and increased fat infiltration. Skeletal muscle regeneration is impaired in aged muscle and associated with cell-intrinsic deficits in satellite cell function; however, satellite cell contribution to sarcopenia has been recently questioned, although a contribution of satellite cell loss to aging-associated fibrosis is supported.

Satellite cells in G0 phase reside within the musculature and are poised to rapidly activate in response to injury. Upon activation, satellite cells re-enter the cell cycle, migrate away from their niche, and proliferate as myoblasts, eventually undergoing terminal differentiation into myocytes that fuse into pre-existing damaged muscle fibers or fuse to one another generating new muscle fibers. During regeneration, a portion of satellite cells returns to its niche, re-enters quiescence, and expresses Pax7 but no other myogenic transcription factors. The transmembrane heparan sulfate proteoglycan syndecan-3, a component of the satellite cell niche, controls satellite cell homeostasis by regulating signaling pathways within the niche. Moreover, members of the Syndecan family regulate cell-cell adhesion and cell-matrix adhesion via interaction with integrins and cadherins. Following a muscle injury, syndecan-3 null (Sdc3-/-) satellite cells fail to replenish the resident pool of quiescent satellite cells within the niche and therefore syndecan-3 appears to regulate satellite cell homeostasis.

We show that syndecan-3 loss alters satellite cell adhesion to the myofiber, altering interactions with the niche and (i) improves muscle regeneration upon repeated acute muscle injuries, (ii) rescues muscle histopathology and function in dystrophic muscle tissue, and (iii) improves muscle aging with a reduction in fibrosis. The lifelong improvement in muscle regeneration observed in Sdc3-/- muscle arises in part by altered satellite cell homeostasis and changes in satellite cell adhesiveness to the myofiber.

Age-Related Inflammation and its Effects on the Generation of Immune Cells

With age, the immune system falls into a state of ever increasing chronic inflammation, a process known as inflammaging: the immune system is overactive, but nonetheless declines in effectiveness at the same time. Researchers here consider how inflammaging can damage the bone marrow stem cell populations responsible for generating immune cells, possibly the basis for a vicious cycle in which the failures of the immune system feed upon themselves to accelerate age-related damage and dysfunction.

Hematopoiesis is an active, continuous process involving the production and consumption of mature blood cells that constitute the hemato-lymphoid system. All blood cells arise from a small population of hematopoietic stem cells (HSCs) in the bone marrow (BM) that have two unique properties: self-renewing capacity, the ability to generate themselves, and multi-lineage differentiation capacity, the ability to produce all blood cell types. Since, in the steady state, most adult HSCs are in the G0 phase of the cell cycle, i.e., they are quiescent and are estimated to turnover slowly on a monthly time scale, daily hematopoietic production is mainly sustained by highly proliferative downstream hematopoietic progenitor cells (HPCs).

Aging of the hematopoietic system is represented by functional declines in both the adaptive and the innate immune system, an immunosenescence that leads to high susceptibility to infections, low efficacy of vaccinations, and increased vulnerability to the development of autoimmunity and hematologic malignancies. It has been show that (a) B cell production decreases significantly with advancing age, i.e., the naïve B cell pool diminishes, while the memory B cell pool expands. Diversity of the B cell repertoire also decreases in association with lowered antibody affinity and impaired class switching. B cells are prone to produce auto-antibodies increasing the incidence of spontaneous autoimmunity; (b) de novo T cell production also declines with aging partially due to thymic involution. CD8+ T cells undergo oligoclonal expansion and their repertoire is skewed toward previously encountered antigens, as niches for naïve T cells in peripheral lymphoid tissues become occupied by terminally differentiated cells; (c) NK cells show diminished cytotoxicity and cytokine secretion; (d) although myeloid cells increase in number, their functionality is decreased, e.g., neutrophils migrate less in response to stimuli, and macrophages have reduced phagocytic activity and decreased oxidative burst; and (e) erythropoiesis also declines in elderly people causing frequent anemia, while the thrombocytic lineage has not, to date, been reported to be significantly affected by aging.

There are similarities between hematopoietic alterations during inflammation and those that occur with aging. In response to aging and bacterial infection, myelopoiesis becomes dominant over lymphopoiesis in relation to immunosenescence. Most notably, B-lymphopoiesis is impaired due to a decreased level of E47, a transcription factor essential for B cell development, in aged mice. The aging-associated myeloid dominance and/or adipogenesis in BM might be triggered by increased basal levels of pro-inflammatory cytokines even in the absence of infection. Indeed, levels of circulating pro-inflammatory cytokines, such as IL-6, TNF-α, IL-1Rα, and C-reactive protein, are reportedly upregulated in healthy elderly populations. These observations allow us to hypothesize that "inflammaging" represents a subclinical grade of chronic inflammation possibly contributing to the initiation and/or acceleration of hematopoietic aging.

Since numerous inflammatory factors are increased in aged hematopoietic tissues, and inflammation- and aging-associated hematopoietic changes share common cellular and molecular alterations, it is reasonable to speculate that low-grade inflammation might be involved in hematopoietic aging with reduced fitness of both adaptive and innate immune cells. Given that some hematopoietic phenotypes during inflammation and aging arise from functional alterations in HSCs and progenitor cells (HSPCs), it would be worthwhile to elucidate the underlying common mechanisms. Future research could yield meaningful insights into cell-intrinsic changes in HSPC quantity and quality, e.g., how aspects of HSPC population dynamics such as functional heterogeneity and population size change, whether all subsets of HSCs with a distinct lineage output respond equally to inflammatory stimuli or only the minor fraction is responsive, how the self-renewal and differentiation capacities of HSC are altered on a per-cell basis, and molecular changes in cellular signaling, such as alterations in cellular metabolism, transcriptional networks, epigenetic modifications, and genomic instability. It is also essential to understand to what extent inflammaging-associated cell-extrinsic factors influence HSPC biology, including signals derived from the BM niche, tissue damage/repair, infection, obesity, or the microbiome. In addition, the fundamental task that remains is identification of the factors initially triggering the process of hematopoietic inflammaging. Inflammation- or aging-related external stimuli appear to force quiescent HSCs to proliferate and impair their self-renewal and differentiation capacities, as suggested by evidence that HSC cycling in response to chemotherapy administration or hematopoietic stress accelerates the manifestation of aging phenotypes. These data suggest that the central features of HSCs aging might be attributable to accumulation of a proliferative history that is closely associated with perturbed self-renewal and differentiation.

Inflammation and aging have thus far been seen as two independent pathophysiological processes. However, a growing body of evidence has highlighted biological changes in hematopoiesis and HSCs that are common to both inflammation and aging. Thus, it is likely that sustained inflammatory stimuli contribute to hematopoietic aging and possibly leukemogenesis, supporting the inflammaging concept. Since inflammation and aging might both be involved in increased risk for leukemogenesis, eliminating unwanted inflammaging factors is a potential approach to preserving both HSC and immune functions, and thereby preventing a functional decline in hematopoiesis and the emergence of malignant clones. Future investigation is required to better characterize hematopoietic inflammaging processes at the tissue, cellular, and molecular levels.

Link: http://dx.doi.org/10.3389/fimmu.2016.00502

Immune Function as a Biomarker of Age and Predictor of Remaining Life Expectancy

The immune system declines with age, as the proportion of its cells capable of responding to new threats falls, autoimmunity increases, and the system as a whole enters a state of constant, rising inflammation. The failure of the immune system speeds other forms of damage and dysfunction in aging, as immune cells are responsible for killing potentially harmful cells, such as those that become senescent or precancerous. The immune system also plays important roles in a variety of essential processes, such as wound healing and maintenance of brain tissues. Clearing out the causes of immune system decline will be a necessary part of any future toolkit of rejuvenation therapies. The open access paper linked here is an illustration of the importance of immune function in aging, as markers of its decline correlate with age and remaining life expectancy:

Chronological age, defined as the time elapsed since birth, fails to be an accurate indicator of the rate of the aging process. This is due to the heterogeneity that aging shows in the diverse members of a population. This phenomenon led to the concept of "biological age", which estimates how well an individual functions in comparison with others of the same chronological age. Given that biological age is a better indicator than chronological age of the health, remaining healthy life span, and active life expectancy of each subject, its determination is very relevant. However, despite its simple definition, quantification of the biological age is a difficult task. Many studies have been carried out trying to obtain the most appropriate parameters for determining biological age and have been mainly focused on both physiological (respiratory function, systolic arterial tension) as well as on biochemical (albumin, cholesterol) markers. Moreover, other markers such as genetic (telomere length) or epigenetic (DNA methylation) have also been proposed. Nevertheless, despite different sets of markers being proposed in these studies, none of them have been validated. Therefore, the subject is still incomplete and more research should be carried out.

Most work on biological age has not included parameters of the immune system, which is a homeostatic system that contributes to the appropriate function of the organism. It is well known that with aging there is an increased susceptibility to infectious diseases, autoimmune processes and cancer, which indicates the presence of a less competent immune system, exerting a great influence on age-related morbidity and mortality. Since it has been demonstrated that the functioning of the immune system is an excellent marker of health and given that several age-related changes in immune functions have been linked to longevity whereas others have been shown to be predictive of mortality, the aim of the present study was to determine if some immune functions could be useful as markers of biological age and therefore as predictors of longevity.

In order to validate a potential set of parameters as markers of biological age, it is necessary to confirm that the levels shown in particular subjects reveal their real health and senescent conditions and, consequently, their rate of aging. This has to be demonstrated by meeting two requirements. The first is that if an adult individual shows values characteristic of a chronologically old individual, he or she should die prematurely. The second is that a long-lived individual, known to have experienced healthy aging, should have a value of these biomarkers similar to that of an adult. The first requisite can only be confirmed in experimental animals, given that it is a difficult task to follow-up human subjects throughout the whole aging process due to their long life span. Thus, mice were chosen for our study, which show a mean longevity of about 2 years. The second requirement can be confirmed in both human centenarians and experimental animals such as extremely long-lived mice.

Among all the possible functions of immune cells, we have focused on the ones that are the most relevant in the immune response and are known to experience an age-related decrease. In phagocytes, their ability to migrate towards the focus of infection (chemotaxis) and their capacity to ingest foreign particles (phagocytosis); in natural killer (NK) cells, their capacity to destroy tumoral cells and in lymphocytes, their ability to migrate towards the site of antigen recognition (chemotaxis) and to proliferate in response to mitogens (lymphoproliferation). Thus, in order to validate the above mentioned immune functions as markers of biological age and predictors of longevity, these functions were studied in leukocytes isolated from peripheral blood of human subjects in a cross-sectional study, from their 30s until their 100s. In addition, the same functions were analyzed in leukocytes obtained from peritoneum of mice without killing them, enabling a longitudinal study to be performed, starting at the adult age and following each animal until its death. Neutrophil chemotaxis and phagocytosis, as well as the activity of NK cells, lymphocyte chemotaxis and proliferative response showed lower values in old individuals in comparison to those in adults. Considering the state of these functions in subjects which reach a high longevity, and consequently have attained successful aging, both humans and mice showed more similar values to those observed at adult age than to those at old age.

Link: http://dx.doi.org/10.18632/aging.101116

ErythroMer as a Step Forward in Artificial Blood

A recent conference presentation on the artificial blood product ErythroMer has been doing the rounds in the press in the past few days. It sounds like the researchers involved have made meaningful progress towards overcoming many of the practical hurdles that have halted similar lines of work. You might take a look back in the Fight Aging! archives for a good open access review that covers many of the attempts to create nanoparticles and cell-like entities that can usefully augment the principal activities of red blood cells. There have been many more challenges in this line of work than might immediately spring to mind, and it makes for interesting reading. ErythroMer is a nanoparticle rather than cell based approach, which is the side of the house that I see as having the greatest potential to exceed present capabilities of our evolved blood and oxygen transport systems. So it is good to see progress on this front; it is most likely from blood substitute nanoparticles that future oxygenation enhancement technologies will arise, offering greater physical robustness and resilience to injury.

There are many lines of research that aim to produce some form of artificial blood, whether built on existing biochemistry and the mass production of cells or cell-like entities, or constructed from first principles as an oxygen-bearing nanoparticle of some form. Even narrowly effective forms of artificial blood with limited uses might nonetheless offer sizable benefits. For example, consider a form of nanoparticle that cannot be used in the long term, but can nonetheless efficiently carry oxygen: this can form the basis for a cost-effective substitute for the large amounts of blood used in trauma cases. Alternatively, a way to mass produce normal red blood cells with specific blood groups would do away with the need for the infrastructure of blood donation and thus make the whole business of banking blood much cheaper. Alternatively again, nanoparticles are much smaller than red blood cells, yet can be engineered to carry more oxygen than those blood cells. In cases of stroke, heart attack, or other ischemic injuries nanoparticles can delivery oxygen to areas that blood cells cannot reach, as well as increase the levels of oxygen reaching all tissues in the body. It isn't just a matter of therapies for the damaged, either. When thinking about enhancement of healthy physiology, something that is a little further out in the future, if today's best oxygen-carrying nanoparticles could be made safe for the long term, then when fully oxygenated an individual could undertake activity for thirty minutes or more without needing to breathe. Food for thought.

Just-Add-Water: Artificial Blood Cells Could Offer Convenient, Portable Alternative to Blood Transfusion

Researchers have developed the first artificial red blood cells designed to emulate vital functions of natural red blood cells. If confirmed safe for use in humans, the nanotechnology-based product could represent an innovative alternative to blood transfusions. The artificial cells, called ErythroMer, are designed to be freeze-dried, stored at ambient temperatures, and simply reconstituted with water when needed. Proof-of-concept studies in mice demonstrate that the artificial cells capture oxygen in the lungs and release it to tissues - the main functions of red blood cells - in a pattern that is indistinguishable from that seen in a control group of mice injected with their own blood. In rats, ErythroMer effectively resuscitated animals in shock following acute loss of 40 percent of their blood volume.

The donut-shaped artificial cells are formulated with nanotechnology and are about one-fiftieth the size of human red blood cells. A special lining encodes a control system that links ErythroMer oxygen binding to changes in blood pH, thus enhancing oxygen acquisition in the lungs and then dispensing oxygen in tissues with the greatest need. Tests show ErythroMer matches this vital oxygen binding feature of human red blood cells within 10 percent, a level the researchers say should be sufficient to stabilize a bleeding patient until a blood transfusion can be obtained. So far, tests suggest ErythroMer has overcome key barriers that halted development of previous blood substitutes, including efficacy and blood vessel narrowing. The team's next steps are testing in larger animals, ongoing safety assessment, optimizing pharmacokinetics, and ultimately conducting in-human clinical trials. The researchers are also pursuing methods for scaling up production. If further testing goes well, they estimate ErythroMer could be ready for use within 10-12 years.

ErythroMer Blood Substitute

4.5 million Americans receive blood transfusions each year, but human blood is limited by its supply and availability. under development, including Perfluorocarbon-Based Oxygen Carriers (PBOC) and Cell-Free Hemoglobin Based Carriers (HBOC), have mostly failed to preserve key physiologic functions of human blood cells. An effective artificial blood substitute will likely create and fulfill market demands for applications including hemorrhagic shock and emergency blood supplies. ErythroMer is a novel blood substitute composed of a patented nanobialys nanoparticle. Existing blood substitutes under development often trap nitric oxide unintentionally and fail to release oxygen in a context-specific manner. ErythroMer has multiple unique advantages by design: (1) Toroidal morphology resembling red blood cells; (2) Physiologic oxygen binding and release; (3) Simple system to inhibit hemoglobin auto-oxidation; (4) Limited nitric oxide sequestration; (5) Amenability to freeze-drying (lyophilization) and reconstitution. As a validation of these advantages, ErythroMer has been shown to demonstrate superior performance than other blood substitutes in a rodent model.

Erythromer (EM), a Nanoscale Bio-Synthetic Artificial Red Cell: Proof of Concept and In Vivo Efficacy Results

There is need for an artificial oxygen (O2) carrier for use when stored blood is unavailable or undesirable. To date, efforts to develop hemoglobin (Hb) based oxygen carriers (HBOCs) have failed, because of design flaws which do not preserve physiologic interactions of Hb with: O2 (they capture O2 in lungs, but do not release O2 effectively to tissue) and nitric oxide (NO) (they trap NO, causing vasoconstriction). ErythroMer design surmounts these weaknesses by: encapsulating Hb, controlling O2 capture/release with a novel 2,3-DPG shuttle and attenuating NO uptake through shell properties. The ErythroMer prototype has passed rigorous initial ex vivo and in vivo "proof of concept" testing and bench testing, which suggests this design surmounts prior challenges (by HBOCs) in emulating normal RBC physiologic interactions with O2 and NO. In models of major bleeding/anemia, ErythroMer reconstitutes normal hemodynamics and O2 delivery, observed at the system, tissue, and cellular level. ErythroMer potential for extended ambient dry storage has significant implications for portability and use. Next steps include formulation scaling, detailed study of pharmacokinetics, biodistribution and safety, as well as evaluation in large animal models of hemorrhagic shock.

Evaluating the Effects of Calorie Restriction on Biomarkers of Human Health and Aging

This very readable open access paper is illustrative of the sort of work presently taking place to try to put some numbers to the effects of calorie restriction in humans, though note that these researchers are very focused on the harms caused by excess visceral fat tissue rather than other possible mechanisms. When it comes to the practice of calorie restriction there is plenty of data for the short term benefits to health, and via existing epidemiological studies that can be extrapolated the longer term reduced risk of age-related disease, but there is very little data that sheds light on the degree to which calorie restriction should be expected to extend human life expectancy. We know it won't do as much for human life span as it does for mice, as human life expectancy is much less plastic in response to circumstances. If eating less produced a life span half as long again in our species, as it can in mice, we'd certainly know about it by now. One of the challenges for researchers in the field is to explain the reasons for this difference, given that the short term changes in mice and humans resulting from calorie restriction are in fact very similar.

Aging and wrong lifestyle choices, including inadequate dietary patterns, increase the risk of developing several diseases such as obesity and its-related chronic degenerative diseases. Interestingly, the aging program can be accelerated by obesity. It is thus likely that obesity reduces life- and health span and plays a predominant role in the onset of age-related diseases. In fact, the prevalence of obesity is globally increasing in populations and has become a burden for healthcare systems. Several studies suggest that dietary restriction (DR) regimens (e.g. intermittent fasting, calorie restriction, low calorie diet) reverse obesity and improve health in human by promoting the same molecular and metabolic adaptations that have been shown in animal models of longevity. In particular, DR in humans ameliorates several metabolic and hormonal factors that are implicated in the pathogenesis of an array of age-associated chronic metabolic diseases.

At present it is difficult to evaluate the effectiveness of DR on lifespan in humans, so that several works proposed predictive non-invasive biomarkers to evaluate the geroprotective role of DR. However, a miscellaneous of biomarkers is investigated in human intervention studies limiting the statistical robustness of the data. Whether a "biomarker-based" approach could be suitable for evaluating the effectiveness of DR still remains a matter of debate. Precision medicine is a medical model that proposes the customization of healthcare, with the identification of predictors that can help to find the effectiveness of health-promoting dietary interventions. Biomarkers represent potentially predictive tools for precision medicine but, although affordable 'omics'-based technology has enabled faster identification of putative biomarkers, their validation is still hindered by low statistical power as well as limited reproducibility of results. Herein, through meta-analysis we have evaluated the effect size of DR regimens on adipose mass and well-recognized biomarkers of healthy aging.

Herein we included all studies evaluating the impact of DR on several healthy-associated markers in human including adipose mass. Increased visceral adiposity leads to chronic inflammation, which is often associated with a number of comorbidities (e.g. hyperinsulinemia, hypertension, insulin resistance, glucose intolerance) and reduced life expectancy. Through this meta-analysis approach, we confirmed the capacity of DR to reduce total and visceral adipose mass and, interestingly, we observed a more effective visceral adipose mass reduction after DR regimens. These findings suggest that to obtain a more effective adipose mass loss, 20% in calorie reduction could be an elective strategy. Central or visceral adiposity perturbs systemic inflammation in animal models and human and relatively to this, the healthy effects of DR could be mediated by visceral adiposity reduction. Indeed, DR significantly diminished the markers of inflammation, highlighting the central role of DR-mediated adipose tissue remodelling in improving inflammatory profile in human. Furthermore, DR also increased adiponectin/leptin ratio, which is commonly associated with ameliorated insulin sensitivity in human. In line with this effect, we demonstrated that DR was successful in reducing insulin, IGF-1 and HOMA index.

Link: http://dx.doi.org/10.18632/aging.101122

Fewer Defects in RNA Splicing Linked to Multiple Ways of Slowing Aging

Researchers have found a common underlying mechanism that appears necessary for the modest slowing of aging achieved via a variety of methods, including calorie restriction and mechanisms related to the mTOR pathway. Since most aspects of cellular biochemistry influence one another, and most methods of slowing aging have (a) a very similar range of effects and (b) don't appear to stack with one another, it shouldn't be surprising that researchers continue to find shared underlying molecular machinery.

Researchers have linked the function of a core component of cells' machinery - which cuts and rejoins RNA molecules in a process known as "RNA splicing" - with longevity in the roundworm. The finding sheds light on the biological role of splicing in lifespan and suggests that manipulating specific splicing factors in humans might help promote healthy aging. "What kills neurons in Alzheimer's is certainly different from what causes cardiovascular disease, but the shared underlying risk factor for these illnesses is really age itself. So one of the big questions is: Is there a unifying theme that unfolds molecularly within various organ systems and allows these diseases to take hold?"

Due to advances in public health, life expectancy has dramatically increased worldwide over the last century. Although people are generally living longer lives, they are not necessarily living healthier lives, particularly in their last decades. Age-related diseases such as cancer, heart disease, and neurodegenerative disease are now among the leading global health burdens - a problem that will likely only worsen. In order for bodies - and cells - to maintain youthfulness, they must also maintain proper homeostasis. At the cellular level, that means keeping the flow of biological information, from genes to RNA to proteins, running smoothly and with the right balance. While a considerable amount is known about how dysfunction at the two ends of this process - genes and proteins - can accelerate aging, strikingly little is known about how the middle part, which includes RNA splicing, influences aging. Splicing enables one gene to generate multiple proteins that can act in different ways and in disparate parts of the body. "Although we know that specific splicing defects can lead to disease, we were really intrigued about de-regulation of RNA splicing as a driver of the aging process itself, because practically nothing is known about that. Put simply, splicing is a way for organisms to generate complexity from a relatively limited number of genes."

Researchers designed a series of experiments in the roundworm Caenorhabditis elegans to probe the potential connections between splicing and aging. "C. elegans is a great tool to study aging in because the worms only live for about three weeks, yet during that time they can show clear signs of age. For example, they lose muscle mass and experience declines in fertility as well as immune function." Notably, the worms' cells are transparent, so researchers harnessed fluorescent genetic tools to visualize the splicing of a single gene in real-time throughout the aging process. Not only did the scientists observe variability on a population level - after five days, some worms showed a youthful pattern of splicing while others exhibited one indicative of premature aging - but they could also use these differences in splicing (reflected fluorescently) to predict individual worms' lifespans prior to any overt signs of old age.

Interestingly, when the team looked at worms treated in ways that increase lifespan (through a technique known as dietary restriction), they found that the youthful splicing pattern was maintained throughout the worms' lives. Importantly, the phenomenon is not restricted to just one gene, but affects genes across the C. elegans genome. The finding suggests that splicing could play a broad role in the aging process, both in worms as well as humans. As they dug more deeply into the molecular links between splicing and aging, researchers zeroed in on one particular component of the splicing apparatus in worms, called splicing factor 1 (SFA-1) - a factor also present in humans. In a series of experiments, the researchers demonstrate that this factor plays a key role in pathways related to aging. SFA-1 is specifically required for lifespan extension by dietary restriction and by modulation of the TORC1 pathway components AMPK, RAGA-1 and RSKS-1/S6 kinase. Remarkably, when SFA-1 is present at abnormally high levels, it is sufficient on its own to extend lifespan.

Link: https://www.hsph.harvard.edu/news/press-releases/uncovering-smoking-gun-in-age-related-disease/

Angiotensin Receptor Autoimmunity Correlates with Age-Related Frailty and Hypertension

Autoimmunity is the name given to a very large class of conditions in which the immune system malfunctions and attacks the body's own cells and machinery. Each different inappropriate target produces a different autoimmune condition, ranging from demyelination diseases like multiple sclerosis, in which the immune system attacks processes and molecules necessary for maintenance of the sheath of myelin that coats nerves, to inflammatory diseases such as rheumatoid arthritis, in which the most obvious damage occurs at the joints. In between lie autoimmune conditions for near every important aspect of our biochemistry. While it is true that the best known autoimmune conditions are not all that age-related - rheumatoid arthritis is noted as "a disease of young women" by some sources, for example - autoimmunity in the general sense does grow with age. The immune system is immensely complex even when working correctly, but the dark forest of the aged, dsyfunctional immune system is especially poorly mapped. New forms of autoimmunity and other immune system malfunctions are discovered on a regular basis. Look at the recent unveiling of type 4 diabetes as a more esoteric example of the age-damaged immune system causing issues in important tissues. It is a condition that is probably quite prevalent in the old, yet missed until now. There are no doubt a great many forms of autoimmune disease presently hiding in the margins of age-related frailty and medical conditions, yet to be cataloged and understood.

Given that the mapping of the immune system and the catalog of autoimmunity is so far from being complete, I would argue that we should devote more attention and funding towards shortcut therapies based on immune ablation and reconstruction. Researchers have in recent years cured known forms autoimmunity with very high dose immunosuppressant or chemotherapy regimes, wiping out the overwhelming majority of immunity cells, then allowing the body to repopulate its immune system naturally. Since the configuration of the immune system, including any mistaken tendency to attack the body's own tissues, is stored in its varied cell populations, this is roughly equivalent to wiping the slate and starting over. Though the cell and tissue damage of aging isn't addressed, only the harmful alterations to immune system configuration that have accumulated over the years, there is the potential to turn back some of the clock here. Unfortunately, while successful, the processes currently used to destroy immune cells with the necessary degree of completeness are dangerous enough, both in immediate risk of death and in long-term damage to health, to only be worth it when the autoimmune condition is very harmful. That is changing, however, with the advent of side-effect-free approaches to targeted cell killing such as the c-kit and CD47 method demonstrated earlier this year, or the approach that Oisin Biotechnologies uses to destroy senescent cells.

The important point here is that clearing and recreating the immune system doesn't just deal with the autoimmunity known to the research community. It also deals with the autoimmunity that isn't known, and scientists have good reason to believe that there is quite a lot of that still hiding in the woodwork. As an example of the type, I'll point out the research linked below, in which the authors find a correlation between (a) a form of autoimmunity targeting components of the angiotensin system, which is responsible for managing blood pressure and sodium levels, and (b) the risk and degree of age-related frailty and hypertension, or raised blood pressure. The more that your own immune system is actively sabotaging the machinery, the worse off you are, in other words, and this is just one of the more subtle cases in which this is shown to be the case. It is interesting to observe that the harmful effects of this form of autoimmunity are modestly reduced by one of the classes of drug that has come into use to lower blood pressure, angiotensin receptor blockers. Thus the benefits of this type of medicine may turn out to result in part from effects that were not at all intentional. Hypertension, of course, is tremendously damaging, and it is absolutely correct to try to reduce age-related increases in blood pressure. It drives numerous forms of cardiovascular disease, from harmful remodeling and weakening of heart tissue, to increased breakage of small blood vessels in the brain, to structural failure of large blood vessels weakened by atherosclerosis. It isn't good at all.

New Link Discovered Between Class of Rogue Autoantibodies and Poor Health Outcomes

Results of a new study led offer new evidence for a strong link between angiotensin receptor autoantibodies and increased risk of frailty. The team says a large class of common blood pressure drugs that target the angiotensin receptor, called angiotensin receptor blockers (ARBs), may help patients depending on the levels of the autoantibodies. In healthy individuals, immune cells produce proteins called antibodies that attack foreign invaders to destroy them and clear them out of the system. In contrast, with autoimmune disorders, the immune cells produce autoantibodies that target the body's own tissue. "We discovered that frail older individuals have markedly higher levels of an autoantibody against its own angiotensin system. The angiotensin system is a key hormonal system that regulates blood pressure and fluid balance. The presence of these antibodies in this subset of vulnerable older adults was associated with increased inflammatory burden, and with decline in grip strength, walking speed and increased number of falls."

Individuals with higher levels of autoantibodies were also more likely to suffer from higher blood pressure. The use of ARBs in such individuals correlated with better control of their blood pressure, suggesting a possible personalized medicine approach to high blood pressure treatment in older adults.Some older adults become frail as they age, and this frailty has been associated with chronic inflammation. To examine the relationship between autoantibody levels and frailty, the research team first recruited 255 participants ages 20 to 93 in Baltimore, Maryland. Participants were separated into two categories: 169 younger adults (ages 20 to 69) and 87 older adults (70 and older). The team measured blood levels of autoantibodies and found that older adults had nearly twice the levels of autoantibodies than the younger adults - a median of 7.3 micrograms per milliliter of blood compared to the younger adult group's median level of 3.76. The researchers then used a frailty screening tool to identify frail older adults by measuring grip strength and walking speed, and asking questions about weight loss, fatigue and levels of physical activity. Older adults with high autoantibody levels were 3.9 times more likely to be frail. For every 1 microgram per milliliter of blood increase in autoantibodies, the researchers observed a decrease in hand grip strength of 5.7 pounds. Additionally, every 1 microgram per milliliter of blood increase in autoantibodies increased the odds of falling by 30 percent.

"Building off of our knowledge that these autoantibodies cause chronic inflammation, we decided to look at a class of medications, angiotensin receptor blockers, that block inflammation and are commonly prescribed to lower blood pressure." To examine the effects of autoantibodies levels on ARBs, the team collected 20-year-old data from a second patient population in Chicago and measured patients' previously collected serum for autoantibody levels. The 60 participants were 70 to 90 years old, and half had been treated with ARBs. The researchers observed similar associations between autoantibody levels and decline in grip strength and walking speed in the Chicago population. Furthermore, for every 1 microgram per milliliter increase of autoantibodies, those not receiving ARBs lived 115 days less - approximately shortened life span by 9 percent. Chronic treatment with ARBs attenuated the autoantibodies' association with decline in grip strength and increased mortality.

Discovery and Validation of Agonistic Angiotensin Receptor Autoantibodies as Biomarkers of Adverse Outcomes

Agonistic angiotensin II type I receptor autoantibodies (AT1RaAbs) have not been associated with functional measures or risk for adverse health outcomes. AT1RaAbs could be utilized to stratify patient risk and to identify patients who can benefit from angiotensin receptor blocker (ARB) treatment. Demographic and physiologic covariates were measured in a discovery set of community dwelling adults from Baltimore (N=255) and AT1RaAb associations with physical function tests and outcomes assessed. A group from Chicago (N=60) was used for validation of associations and to explore the impact of ARB treatment.

The Baltimore group had 28 subjects with falls, 32 frail subjects and 5 deaths. Higher AT1RaAbs correlated significantly with interleukin-6, systolic blood pressure, body mass index (BMI), weaker grip strength, and slower walking speed. Individuals with high AT1RaAbs were 3.9 times more likely to be at high risk after adjusting for age. Every 1 µg/ml increase in AT1RaAbs increased the odds of falling 30% after adjusting for age, gender, BMI and blood pressure. The Chicago group had 46 subjects with falls and 60 deaths. Serum AT1RaAb levels were significantly correlated with grip strength, walking speed and falls. Every 1 µg/ml increase in AT1RaAbs, decreased time to death by 9% after adjusting for age, gender, BMI and blood pressure. Chronic treatment with ARBs was associated with better control of systolic blood pressure and attenuation of decline in both grip strength and time to death.

Long Telomeres may also be Problematic

Researchers here provide initial evidence to suggest that very long telomeres may be problematic in human cells - that manipulating our biochemistry to push telomere length outside evolved norms in either direction will cause issues. Telomeres are repeated DNA sequences that cap the ends of chromosomes. There is considerable interest in telomere length in connection with aging, as average telomere length diminishes with age, though this is a statistical effect across populations and not very useful for individual predictions. There is a lot of variation over time and by health status in any given individual and between any two individuals of the same age and fitness. On the whole telomere length looks a lot like a marker of aging rather than the cause of problems: the groups that primarily seek to engineer longer telomeres in search of a way to slow aging are probably putting the cart before the horse.

Tissues are made up of somatic cells that are restricted in the number of divisions they can undertake, and supported by a small number of stem cells that are not restricted in that way. Each cell division results in a loss of telomere length, and once telomeres are too short the cell becomes senescent or self-destructs. New cells with long telomeres are created by stem cells, and those stem cells maintain long telomeres themselves via the use of telomerase. Thus average telomere length in somatic cells would seem to be a measure of some combination of stem cell activity and cell division rates - and it is known that stem cell populations decline with age. Researchers have demonstrated slowed aging in mice through increased telomerase activity, but it is far from clear as to identity of the important mechanisms in this effect: greater stem cell activity seems the most plausible, but there are a range of other options.

Ever since researchers connected the shortening of telomeres - the protective structures on the ends of chromosomes - to aging and disease, the race has been on to understand the factors that govern telomere length. Now, scientists have found that a balance of elongation and trimming in stem cells results in telomeres that are, as Goldilocks would say, not too short and not too long, but just right. "This work shows that the optimal length for telomeres is a carefully regulated range between two extremes. It was known that very short telomeres cause harm to a cell. But what was totally unexpected was our finding that damage also occurs when telomeres are very long."

Telomeres are repetitive stretches of DNA at the ends of each chromosome whose length can be increased by an enzyme called telomerase. Our cellular machinery results in a little bit of the telomere becoming lopped off each time cells replicate their DNA and divide. As telomeres shorten over time, the chromosomes themselves become vulnerable to damage. Eventually the cells die. The exception is stem cells, which use telomerase to rebuild their telomeres, allowing them to retain their ability to divide, and to develop ("differentiate") into virtually any cell type for the specific tissue or organ, be it skin, heart, liver or muscle - a quality known as pluripotency. These qualities make stem cells promising tools for regenerative therapies to combat age-related cellular damage and disease. "In our experiments, limiting telomere length compromised pluripotency, and even resulted in stem cell death. So then we wanted to know if increasing telomere length increased pluripotent capacity. Surprisingly, we found that over-elongated telomeres are more fragile and accumulate DNA damage."

The reasearchers began by investigating telomere maintenance in laboratory-cultured lines of human embryonic stem cells (ESCs). Using molecular techniques, they varied telomerase activity. Perhaps not surprisingly, cells with too little telomerase had very short telomeres and eventually the cells died. Conversely, cells with augmented levels of telomerase had very long telomeres. But instead of these cells thriving, their telomeres developed instabilities. "We were surprised to find that forcing cells to generate really long telomeres caused telomeric fragility, which can lead to initiation of cancer. These experiments question the generally accepted notion that artificially increasing telomeres could lengthen life or improve the health of an organism."

The team observed that very long telomeres activated trimming mechanisms controlled by a pair of proteins called XRCC3 and Nbs1. The lab's experiments show that reduced expression of these proteins in ESCs prevented telomere trimming, confirming that XRCC3 and Nbs1 are indeed responsible for that task. Next, the team looked at induced pluripotent stem cells (iPSCs), which are differentiated cells (e.g., skin cells) that are reprogrammed back to a stem cell-like state. iPSCs - because they can be genetically matched to donors and are easily obtainable - are common and crucial tools for potential stem cell therapies. The researchers discovered that iPSCs contain markers of telomere trimming, making their presence a useful gauge of how successfully a cell has been reprogrammed. "Stem cell reprogramming is a major scientific breakthrough, but the methods are still being perfected. Understanding how telomere length is regulated is an important step toward realizing the promise of stem cell therapies and regenerative medicine."

Link: http://www.salk.edu/news-release/goldilocks-effect-aging-research/

The Latest on Chimeric Antigen Receptor Therapy for Leukemia

The use of chimeric antigen receptors (CAR) to create engineered T cells to attack specific varieties of cancer cell, identified by their surface chemistry, is so far proving to be effective for leukemia, a cancer of the immune system. Researchers are also making inroads in adapting the therapy for use in solid tumors. While an initial group of patients treated several years ago with the first pass at CAR T cell therapy remain in remission, the news here focuses on the results from a more recent trial:

The 24 patients had undergone most standard therapies available to them and yet their chronic lymphocytic leukemia had come back strong. Almost all of them had been treated with a newly approved, targeted drug called ibrutinib; data from other studies show that most patients whose disease progresses after ibrutinib treatment do not survive long. The majority of the 24 had chromosomal markers in their leukemia cells that serve as predictors of a bad response to most standard therapies. But most of these patients, who were enrolled in a small, early-phase trial, saw their advanced tumors shrink or even disappear after an infusion of genetically engineered immune cells.

In the trial, participants' disease-fighting T cells were removed from their blood and genetically engineered to produce an artificial receptor, called a CAR, or chimeric antigen receptor, that empowered them to recognize and destroy cancer cells bearing a target molecule called CD19. After patients received chemotherapy, the CAR T cells were infused back into their bloodstream to kill their CD19-positive cancers. While all 24 patients with chronic lymphocytic leukemia, or CLL, received the experimental therapy, researchers focused in his presentation on the results in a subgroup of 19 patients who received particular chemotherapy regimens and doses of CAR T cells the researchers now prefer, based on recent data in other groups of patients on the trial. Fourteen of 19 experienced a partial or complete regression of their disease in their lymph nodes. And of the 17 who had leukemia in their bone marrow when they enrolled on the trial, the marrow became cancer-free in 15 after they received CAR T cells. "It's very pleasing to see patients with refractory disease respond like this. We had seen very good responses to the same CAR T-cell therapy in acute lymphoblastic leukemia and non-Hodgkin lymphoma, so we hoped responses would be good in CLL too."

Follow-up with CLL participants is ongoing. As per U.S. Food and Drug Administration requirements for experimental gene therapies, the research team will track patient outcomes for at least 15 years. Researchers reported that the CLL patients with the highest number of CAR T cells in their blood after infusion were most often the patients who had had the greatest extent of cancer in their marrow, blood and lymph nodes at the time of infusion. Those with more CAR T cells were also most likely to have their disease disappear from the bone marrow after the cells entered their bodies. Side effects included high fevers, due to activation of CAR T cells, and neurologic symptoms. Although one patient died from severe toxicity, the side effects experienced by other patients in the study were temporary. The researchers also reported biomarkers they had identified in patients' blood from the day after CAR T-cell infusion that were associated with the later development of the most severe toxicities. They hope these markers could eventually become the cornerstone of tests to predict and mitigate the most serious side effects of CAR T-cell infusion. "If you can find biomarkers within a day of CAR T-cell infusion, which we have, you can then look at future cohorts of patients to work out whether early intervention can help prevent toxicity."

Link: http://www.fredhutch.org/en/news/center-news/2016/12/promising-results-in-trial-of-t-cells-in-high-risk-leukemia.html

An Important Step Forward Towards a Vaccine for Periodontal Disease

The various types of gum disease and periodontal conditions create insidious forms of damage, caused by the presence of unwanted but very persistent species of bacteria found in the mouth. Most people suffer inflammation of the gums to some degree, and this is due to the activities of bacteria such as Porphyromonas gingivalis. While it is true that there are a large number of ways to remove the bacterial species found in the mouth, the challenge is that they always return, and do so very quickly, often within days. This is obviously important from the point of view of the quality of your teeth over the long term, but arguably the real reason to pay attention here is because inflammation and damage in the gums directly correlates with inflammation and damage to the heart and the rest of the cardiovascular system. Research has shown that the presence and prevalence of bacterial species associated with gum disease correlates with mortality rates, while gum disease itself correlates with cognitive decline and the presence of amyloid in the brain, to pick a few examples. If you don't keep dental health under control, your risk of suffering all of the cardiovascular diseases that are driven by chronic inflammation increases significantly, and it appears that your chances of suffering dementia get a boost as well. Unfortunately, for the whole of human history, dental health has proven to be a real challenge: gains have been incremental and still require a fair amount of ongoing work on the part of the individual.

Yet we live in an age of biotechnology and rapid, revolutionary progress. It is unthinkable that immunology, genetics, gene therapies, and advanced medical applications of the life sciences can continue to coexist with the fact that we can't get rid of a few simple bacterial species that are causing us considerable harm. Sooner or later the research community will bring all undesirable bacteria under medical control. For some years now, a number of dental research groups have been working on potential methods of permanently excluding the bacteria that cause periodontitis and other inflammatory damage to gums, teeth, and the underlying bone. This has proven to be slow going, unfortunately. Nonetheless there have been signs of progress of late. To pick an example from earlier this year, one research team has managed to rouse the innate immune system into attacking and destroying bacterial species that cause gum disease, reversing the progression of periodontitis. Similarly, the research linked below takes the form of a vaccine, training the immune system to attack one of the problem molecules produced by the Porphyromonas gingivalis bacteria that contribute to periodontitis. The dental research community tends to have a faster time to market and less of a regulatory burden than the rest of the broader medical community, so we might expect to see something along these lines reaching clinics within the next few years.

Scientists publish evidence for world-first therapeutic dental vaccine

A world-first vaccine which could eliminate or at least reduce the need for surgery and antibiotics for severe gum disease has been validated. A team of dental scientists has been working on a vaccine for chronic periodontitis for the past 15 years. Clinical trials on periodontitis patients could potentially begin in 2018. Moderate to severe periodontitis affects one in three adults and more than 50 per cent of Australians over the age of 65. It is associated with diabetes, heart disease, rheumatoid arthritis, dementia and certain cancers. It is a chronic disease that destroys gum tissue and bone supporting teeth, leading to tooth loss.

The findings represent analysis of the vaccine's effectiveness by collaborating groups. The vaccine targets enzymes produced by the bacterium Porphyromonas gingivalis, to trigger an immune response. This response produces antibodies that neutralise the pathogen's destructive toxins. P. gingivalis is known as a keystone pathogen, which means it has the potential to distort the balance of microorganisms in dental plaque, causing disease. "We currently treat periodontitis with professional cleaning sometimes involving surgery and antibiotic regimes. These methods are helpful, but in many cases the bacterium re-establishes in the dental plaque causing a microbiological imbalance so the disease continues. Periodontitis is widespread and destructive. We hold high hopes for this vaccine to improve quality of life for millions of people."

A therapeutic Porphyromonas gingivalis gingipain vaccine induces neutralising IgG1 antibodies that protect against experimental periodontitis

From epidemiological surveys moderate to severe forms of periodontitis affect one in three adults and the disease has been linked to an increased risk of cardiovascular diseases, certain cancers, preterm birth, rheumatoid arthritis and dementia related to the regular bacteremia and chronic inflammation associated with the disease. The global prevalence of severe periodontitis has been estimated from 2010 epidemiological data to be 10.5-12.0% and the global economic impact of dental diseases, of which periodontitis is a major component, has been estimated to be US$442 billion per year. The conventional therapy for periodontitis involves scaling and root planing to remove plaque microorganisms. Treatment can sometimes involve surgery to improve access and/or to reduce pocket depth and can also include the use of antibiotics and/or antimicrobials. However, treatment outcomes are variable and heavily dependent on patient compliance. Even in patients on a periodontal maintenance program involving regular professional intervention sites continue to progress and teeth are lost.

Although chronic periodontitis is associated with a polymicrobial biofilm, specific bacterial species of the biofilm such as Porphyromonas gingivalis, Treponema denticola and Tannerella forsythia as a complex or consortium have been closely associated with clinical measures of disease. P. gingivalis is found at the base of deep periodontal pockets as microcolony blooms in the superficial layers of subgingival plaque adjacent to the periodontal pocket epithelium, which helps explain the strong association with underlying tissue inflammation and bone resorption at relatively low proportions (10-15%) of the total bacterial cell load in the pocket. Furthermore, it has been shown from studies using the mouse periodontitis model that P. gingivalis is a keystone pathogen, which dysregulates the host immune response to favour the polymicrobial biofilm disrupting homeostasis with the host to cause dysbiosis and disease.

The extracellular Arg- and Lys-specific proteinases 'gingipains' (RgpA/B and Kgp) of P. gingivalis have been implicated as major virulence factors that are critical for colonisation, penetration into host tissue, dysregulation of the immune response, dysbiosis and disease. The gingipains, in particular the Lys-specific proteinase Kgp is essential for P. gingivalis to induce alveolar bone resorption in the mouse periodontitis model. The gingipains have also been found in gingival tissue at sites of severe periodontitis at high concentrations proximal to the subgingival plaque and at lower concentrations at distal sites deeper into the gingival tissue. This has led to the development of a cogent mechanism to explain the keystone role played by P. gingivalis in the development of chronic periodontitis.

The role of P. gingivalis as a keystone pathogen in the initiation and progression of chronic periodontitis suggests that a strategy of targeting the major virulence factors of the bacterium, the gingipains, by vaccination may have utility in the prevention of P. gingivalis-induced periodontitis. Indeed, studies using the gingipains as a prophylactic vaccine that induces a high-titre antibody response in naive animals before superinfection with the pathogen have shown protection against alveolar bone resorption. However, patients with P. gingivalis-associated periodontitis harbour the pathogen at above threshold levels in subgingival plaque and exhibit an inflammatory immune response, hence it is possible that therapeutic vaccination could exacerbate inflammation and bone resorption in these patients. Here we show that therapeutic vaccination with a chimera antigen targeting the gingipains protects against alveolar bone resorption in P. gingivalis-associated experimental periodontitis and that this protection is mediated via a predominant Th2 anti-inflammatory response with the production of gingipain-neutralising IgG1 antibodies.

Common Sense on Aging and the Role of Medicine

Ronald Bailey, who has written on and off on the topic of longevity science for about as long as I've been paying attention to the subject myself, here outlines a common sense view of aging and its treatment as a medical condition. That more people are stepping up to make reasoned arguments along these lines is a sign of progress. At the large scale and over the long term, the research that is carried out is that which is supported and understood, at least in outline, by the public at large. Lines of research that aim to control the causes of aging and thereby prevent and cure all age-related disease is not yet widely supported or appreciated, and this is why such research is still a minority concern in the scientific community. There is much work left to be done for patient advocates.

In the 21st century, almost everything that kills people, except for accidents and other unintentional causes of death, has been classified as a disease. Aging kills, so it's past time to declare it a disease too and seek cures for it. In 2015, a group of European gerontologists persuasively argued for doing just that. They rejected the common fatalistic notion that aging "constitutes a natural and universal process, while diseases are seen as deviations from the normal state." A century ago osteoporosis, rheumatoid arthritis, high blood pressure, and senility were considered part of normal aging, but now they are classified as diseases and treated. "There is no disputing the fact that aging is a 'harmful abnormality of bodily structure and function,'" they note. "What is becoming increasingly clear is that aging also has specific causes, each of which can be reduced to a cellular and molecular level, and recognizable signs and symptoms."

So why do people age and die? Basically, because of bad chemistry. People get cancer when chemical signals go haywire enabling tumors to grow. Heart attacks and strokes occur when chemical garbage accumulates in arteries and chemical glitches no longer prevent blood cells from agglomerating into dangerous clumps. The proliferation of chemical errors inside our bodies' cells eventually causes them to shut down and emit inflammatory chemicals that damage still healthy cells. Infectious diseases are essentially invasions of bad chemicals that arouse the chemicals comprising our immune systems to try and (too often) fail to destroy them.

Also in 2015, another group of European researchers pointed out that we've been identifying a lot of biomarkers for detecting the bad chemical changes in tissues and cells before they produce symptoms associated with aging. Such biomarkers enable pharmaceutical companies and physicians to discover and deploy treatments that correct cellular and molecular malfunctions and nudge our bodies' chemistry back toward optimal functioning. As a benchmark, the researchers propose the adoption of an "ideal norm" of health against which to measure anti-aging therapies. "One approach to address this challenge is to assume an 'ideal' disease-free physiological state at a certain age, for example, 25 years of age, and develop a set of interventions to keep the patients as close to that state as possible," they suggest. Most people's body chemistry is at its best when they are in their mid-twenties. In fact, Americans between ages 15 and 24 are nearly 500 times less likely to die of heart disease, 100 times less likely to die of cancer, and 230 times less likely die of influenza and pneumonia than people over the age of 65 years. For lots of us who are no longer in our twenties, television talk show host Dick Cavett summed it up well: "I don't feel old. I feel like a young man that has something wrong with him."

Link: http://reason.com/archives/2016/12/02/time-to-declare-aging-a-disease-and-get

Evidence for the Gut Microbiome to Contribute to Parkinson's Disease

In this open access paper, researchers provide evidence in support of the hypothesis that the development of Parkinson's disease starts in the gut, with changes in the microbiome that promote dysfunction:

Neurological dysfunction is the basis of numerous human diseases. Affected tissues often contain insoluble aggregates of proteins that display altered conformations, a feature believed to contribute to an estimated 50 distinct human diseases. Neurodegenerative amyloid disorders, including Alzheimer's, Huntington's, and Parkinson's diseases (PD), are each associated with a distinct amyloid protein. PD is a multifactorial disorder that has a strong environmental component, as less than 10% of cases are hereditary. Aggregation of α-synuclein (αSyn) is thought to be pathogenic in a family of diseases termed synucleinopathies, which includes PD, multiple system atrophy, and Lewy body disease. αSyn aggregation is a stepwise process, leading to oligomeric species and intransient fibrils that accumulate within neurons. Dopaminergic neurons of the substantia nigra pars compacta (SNpc) appear particularly vulnerable to effects of αSyn aggregates.

Although neurological diseases have been historically studied within the central nervous system (CNS), peripheral influences have been implicated in the onset and/or progression of diseases that impact the brain. Indeed, emerging data suggest bidirectional communication between the gut and the brain. Gastrointestinal (GI) physiology and motility are influenced by signals arising both locally within the gut and from the CNS. Neurotransmitters, immune signaling, hormones, and neuropeptides produced within the gut may, in turn, impact the brain. The human body is permanently colonized by microbes on virtually all environmentally exposed surfaces, the majority of which reside within the GI tract. Increasingly, research is beginning to uncover the profound impacts that the microbiota can have on neurodevelopment and the CNS. Dysbiosis (alterations to the microbial composition) of the human microbiome has been reported in subjects diagnosed with several neurological diseases. For example, fecal and mucosa-associated gut microbes are different between individuals with PD and healthy controls. Yet, how dysbiosis arises and whether this feature contributes to PD pathogenesis remains unknown.

Gut bacteria control the differentiation and function of immune cells in the intestine, periphery, and brain. Intriguingly, subjects with PD exhibit intestinal inflammation, and GI abnormalities such as constipation often precede motor defects by many years. It is posited that aberrant αSyn accumulation initiates in the gut and propagates via the vagus nerve to the brain in a prion-like fashion. This notion is supported by pathophysiologic evidence: αSyn inclusions appear early in the enteric nervous system (ENS) and the glossopharyngeal and vagal nerves. Further, injection of αSyn fibrils into the gut tissue of healthy rodents is sufficient to induce pathology within the vagus nerve and brainstem. However, the notion that αSyn aggregation initiates in the ENS and spreads to the CNS via retrograde transmission remains controversial, and experimental support for a gut microbial connection to PD is lacking.

Based on the common occurrence of GI symptoms in PD, dysbiosis among PD patients, and evidence that the microbiota impacts CNS function, we tested the hypothesis that gut bacteria regulate the hallmark motor deficits and pathophysiology of synucleinopathies. Herein, we report that the microbiota is necessary to promote αSyn pathology, neuroinflammation, and characteristic motor features in a validated mouse model. We identify specific microbial metabolites, short-chain fatty acids, that are sufficient to promote disease symptoms. Remarkably, fecal microbes from PD patients impair motor function significantly more than microbiota from healthy controls when transplanted into mice. Together, these results suggest that gut microbes may play a critical and functional role in the pathogenesis of synucleinopathies such as PD.

Link: http://dx.doi.org/10.1016/j.cell.2016.11.018

The Slow Death of the Self that is Produced by the Normal Operation of Human Memory

People are terrified of dementia, by the loss of the self that results from the final stages of the accumulation of age-related damage in the brain. Whether this is loss of data or merely loss of access to data, that data being encoded in the structures of neurons and their connecting synapses, depends upon the details along the way. Either option amounts to the same thing for someone in the midst of the condition when there is only faint prospect of therapies arriving soon enough to matter. But if dementia is an asymptotic approach to 100% loss of data, what to make of the fact that we are, on a day to day basis, largely accepting of our normal relationship with the data of the mind, in which we lose 98% of everything that we experience within a few weeks of the event? A week from now you will not remember reading this, nor will there be any trace of what took place in the surrounding minutes before and after. You will have to guess at how you spent your time, what you were thinking, who you were at that moment. We are, every one of us, thin and translucent ghosts of our own history, mere summaries of a rich set of data that is now gone.

Yet we get by. Normal is normal, but that doesn't mean it is good, or that it should go unexamined. To put this another way, there was a person who lived a few decades ago in the UK, and got by. Later, there was another person who came to the US and spent time here, as people do. I know about as much about those individuals as I do about friends of long standing, perhaps just a little more. Yet both of them were me. All of that remains of them, of their richness of data, are the echoes I carry with me now. I have the memories burned in by adrenaline or, to a lesser extent, by sheer boring repetition, but those are just signposts in the mist by this point. Ask me who I was back then, and the answer will be largely extrapolation. Are those individuals dead? Am I so different that such a question makes sense to ask? To what extent is the self burning away and vanishing because we have a poor capacity for remembrance? To what extent is change death, in other words? Here of course I do little more than wave my hands at questions that have been debated at great length in the philosophy community.

Those of us who are generally opposed to the idea of being scanned, uploaded, and copied have the view that a copy of the self is not the self. It is its own separate individual. Individuality stems from the combination of pattern of information and the matter that the pattern is bound to. It isn't clear that, for example, an emulation running in an abstraction layer over computing hardware can be considered a continuous entity, rather than a unending series of nanosecond individuals assembled and then destroyed. In the continuity view of identity, a Ship of Theseus sort of a viewpoint, you are still you even if all your component parts are slowly replaced over time. There is a sizable grey area at the border between small parts and slow replacement, which is fine, and large parts and rapid replacement, which is the same as death. If someone removes half of your brain in one go and replaces it with a hypothetical machine that accepts exactly the same inputs and produces exactly the same outputs where it connects to the remaining brain tissue, I would say that this means that you just died, even though an entity that thinks in the same way as you did continues onward. Conversely, replacing neurons one by one with machines that perform the same functions, and allowing time for each neuron to reach equilibrium with its neighbors, seems acceptable.

Continuity comes attached at the hip to change of the self over time. Life is change, and we celebrate it. But we lose so very much in the course of that change that it seems matters really could be better managed. The figure for 98% loss of memory over weeks arises from self-experiments carried out by a determined fellow in the late 1800s, and which have been repeated every so often by the research community ever since. A replication paper was published just last year, for example. This enormous loss is the way things work for normal humans, and coupled with the adrenaline mechanism for selective additional memory of events that matter, one can see how this sort of a system might have evolved. A prehistoric lifespan is the same few tasks with very minor variations repeated over and again until death or disability, interspersed with a much smaller number of painful and terrifying learning experiences, with each new generation running the same rat wheel as the previous.

There are claims of people with extraordinary memory, or even eidetic or photographic memory, but the scientific community is far from settled on the question of the degree to which these claims result from (a) misinterpreting the top end of the curve for normal variation in memory capacity, versus (b) narrowly specialized memory training, versus (c) some form of genuinely unusual and exceptional ability based on neurobiological differences yet to be described. The mechanisms of memory are being deciphered in the laboratory, however, and there are various demonstrations of a modest degree of enhanced memory in animal studies. The question of whether greatly enhanced memory can be induced through near future medicine remains open: it will certainly happen eventually, but when will it start in earnest, and when will it go beyond adding only few more percentage points to the fraction of events we recall from our lives? It seems to me that this is a goal that should be given a far greater priority than is the case today. Consider that if we had perfect memory, what would we think of someone who forget near everything he or she did? We would call it a medical condition and offer support, in the same way that the medical community seeks to treat and aid people suffering age-related cognitive decline or amnesia today. If there were a great many of those people, there would be an enormous investment in the search for a cure, just as we do today for Alzheimer's disease. But because our disability is normal and shared, there is no such effort.

Embryonic Gene Hoxa9 Reactivates with Age to Limit Muscle Stem Cells

The changes that take place in stem cell populations with age are most studied in muscle tissue at the present time. Stem cells in old tissue spend ever more time quiescent rather than active, and thus the supply of new somatic cells needed to maintain and repair muscle declines. From the evidence accumulated to date this appears to be largely driven by changes in signaling rather than molecular damage to the stem cells themselves, though there is that as well. Researchers are attempting to catalog these signals with the hope of overriding them in order to restore youthful levels of regeneration in aged patients, and the research noted here is one example of this type of research. The decline in stem cell activity with age is thought to be part of an evolved balance between death by lack of tissue maintenance on the one hand and death by cancer on the other. Lower rates of stem cell activity reduces the chance of a damaged cell running amok. However, the use of stem cell therapies that change signals to put native cells back to work, and studies of telomerase gene therapy that has much the same effect, so far suggest that there is a fair amount of room to improve the situation without significantly raising the risk of cancer.

The development of the embryo during pregnancy is one of the most complex processes in life. Genes are strongly activated, and developmental pathways must do their job in a highly accurate and precisely timed manner. So-called Hox-genes play an important regulatory role in this process. Although remaining detectable in stem cells of adult tissues throughout life, after birth they are only rarely active. Now, however, researchers have shown that, in old age, one of these Hox-genes (Hoxa9) is strongly re-activated in murine muscle stem cells after injury; leading to a decline in the regenerative capacity of skeletal muscle. Interestingly, when this faulty gene re-activation was inhibited by chemical compounds, muscle regeneration was improved in aging mice, thus suggesting novel therapeutic approaches aimed at improving muscle regeneration in old age.

The biggest surprise from the current study is that the re-activation of Hoxa9 after muscle injury in old age impairs the functionality of muscle stem cells instead of improving it. Originally, Hoxa9-induced developmental pathways are responsible for the proper development of body axes - for example, during development of the fingers of a hand. A decline in stem cell functionality leads to an unavoidable decrease in the regenerative capacity of the whole skeletal muscle. With age, this may weaken the muscular strength after injury. The courses of stem cell and tissue aging are yet to be completely understood. It has already been recognized that signals which control the development of the embryo become activated in aging stem cells. However, the regulator-genes controlling these signals have not yet been analyzed in aging. "From an evolutionary perspective, Hox-genes are very old. They regulate organ development across almost the entire animal kingdom - from flies up to humans. It is a huge surprise that the faulty re-activation of these genes leads to stem cell aging in muscle. This finding will fundamentally influence our understanding of the courses of aging. Surprisingly, old muscle stem cells did not show a faulty activation of the epigenome in quiescence - the resting stage in non-injured muscle. Only in response to a muscle injury, do the stem cells display an abnormal epigenetic stress response, which leads to the opening of DNA and, thus, to the activation of developmental pathways."

The researchers now plan to investigate whether a similar re-activation of embryonic genes is also causative for the loss of muscle maintenance in aging humans. Medical compounds that limit alterations in the epigenome may improve the regenerative capacity of muscles in old mice. Thus far, this approach is too unspecific and affects the modification of genes in several cells and tissues. For this reason, a collaborative study is primed to investigate whether a nanoparticle-induced, target-specific inhibition of Hox-genes in muscle stem cells is feasible and, if so, would it be sufficient to improve muscle regeneration and maintenance.

Link: http://www.leibniz-fli.de/nc/institute/public-relations/press-releases/research/detailpage/?tx_news_pi1%5Bnews%5D=3310

A Reasonable Perspective on Cryonics

In this article, one of the scientists involved in our rejuvenation research community outlines a very reasonable view on cryonics and cryopreservation. Cryonics is the low-temperature preservation of at least the brain following death, done these days with the use of cryoprotectants and vitrifiction to minimize ice crystal formation. It offers an unknown chance at a future restoration to life: technology marches onwards year after year, and for so long as the structures that encode the data of the mind are preserved, there is the possibility of living again in a future age that has mastered the technologies needed for restoration. This would include, at a minimum, comprehensive control over cellular biology and some form of advanced molecular nanotechnology. Even in our present era, there is considerable interest in developing reversible vitrification for organ storage, to ease the logistics of tissue engineering and organ donation and transplantation, and early proof of concept experiments have taken place in that field. The types of technology that would be needed to restore a preserved cryonics patient can be envisaged by extrapolation from present efforts in that field and in the work being carried out on rejuvenation therapies.

A teenager who tragically died of cancer recently has become the latest among a tiny but growing number of people to be cryogenically frozen after death. These individuals were hoping that advances in science will one day allow them to be woken up and cured of the conditions that killed them. But how likely is it that such a day will ever come? Nature has shown us that it is possible to cryopreserve animals like reptiles, amphibians, worms and insects. Nematode worms trained to recognise certain smells retain this memory after being frozen. The wood frog (Rana sylvatica) freezes during winter into a block of ice and hops around the following spring. However, in human tissue each freeze-thaw process causes significant damage. Understanding and minimising this damage is one of the aims of cryobiology.

At the cellular level, these damages are still poorly understood, but can be controlled. Each innovation in the field relies on two aspects: improving preservation during freezing and advancing recovery after thawing. During freezing, damage can be avoided by carefully modulating temperatures and by relying on various types of cryoprotectants. One of the main objectives is to inhibit ice formation which can destroy cells and tissues by displacing and rupturing them. For that reason, a smooth transition to a "glassy stage" (vitrification) by rapid cooling, rather than "freezing", is the aim. Reviving whole bodies also poses its own challenges as organs need to commence function homogeneously. The challenges of restoring the flow of blood to organs and tissues are already well-known in emergency medicine. But it is perhaps encouraging that cooling itself does not only have negative effects - it can actually mitigate trauma. In fact, drowning victims who have been revived seem to have been protected by the cold water - something that has led to longstanding research into using low-temperature approaches during surgery.

The pacemakers of scientific innovation in cryobiology are both medical and economic. Many advances in cell preservation are driven by the infertility sector and an emerging regenerative medicine sector. Cryopreserved and vitrified cells and simple tissues (eggs, sperm, bone marrow, stem cells, cornea, skin) are already regularly thawed and transplanted. Work has also started on cryopreservation of "simple" body parts such as fingers and legs. Some complex organs (kidney, liver, intestines) have been cryopreserved, thawed, and successfully re-transplanted into an animal. While transplantation of human organs currently relies on chilled, not frozen, organs, there is a strengthening case for developing cryopreservation of whole organs for therapeutic purposes.

But there's another huge hurdle for cryonics: to not only repair the damage incurred due to the freezing process but also to reverse the damage that led to death - and in such a manner that the individual resumes conscious existence. So will it one day be possible to cryopreserve a human brain in such a manner that it can be revived intact? Success will depend on the quality of the cryopreservation as well as the quality of the revival technology. Where the former is flawed, as it would be with current technologies, the demands on the latter increase. This has led to the suggestion that effective repair must inevitably rely on highly advanced nanotechnology - a field once considered science fiction. The idea is that tiny, artificial molecular machines could one day repair all sorts of damage to our cells and tissues caused by cryonics extremely quickly, making revival possible. Given the rapid advances in this field, it may seem hasty to dismiss the entire scientific aim behind cryonics.

Link: http://theconversation.com/will-we-ever-be-able-to-bring-cryogenically-frozen-corpses-back-to-life-a-cryobiologist-explains-69500

Support for Impaired Drainage Theories of Alzheimer's Disease

Alzheimer's disease is associated with the growing presence of solid deposits of misfolded amyloid-β and altered tau protein in the brain. A halo of complex and much debated biochemistry connects these forms of metabolic waste with the dysfunction and death of neurons; it isn't the amyloid or the tau itself, but related molecules and their interactions that cause pathology, arising as a result of the existence of the amyloid and tau. Clearing these unwanted proteins should help to turn back the progression of Alzheimer's, a goal complicated by the fact that many Alzheimer's patients also suffer from other forms of neurodegeneration, such as the vascular dementia that results from hypertension, blood vessel stiffness and structural failure, and many tiny zones of cell death caused by blood vessel failures over the years. Unfortunately in addition to these complications, safely clearing amyloid in the human brain has proven to be very challenging. Most efforts to date have used forms of immunotherapy, and only recently have good results emerged in human trials. The field of the past decade is littered with the remains of failed efforts. Clearance of tau has much further to go in order to arrive at the point of human trials, not having received the same level of attention and funding over the past decade. It is becoming apparent that it will also have to be removed from the brain, however.

Why do amyloid and tau aggregate in the aging brain? There are many competing theories. The brain, its immune system, and its surrounding support structures are enormously complex and only partially understood. In many ways the quest to understand Alzheimer's disease is one and the same with the quest to understand the brain as a whole. A cure for Alzheimer's is the goal that brings in funding for fundamental research into the mechanisms of thought, memory, and aging, as well as details of cellular behavior, inflammation and immunology in the brain, distinctly different and more complicated than elsewhere in the body. One interesting point regarding amyloid-β is that its levels in brain tissue and cerebrospinal fluid are very dynamic. It is constantly created and destroyed, and so the accumulation with age is not a matter of slow and steady creation, but rather results from the interaction and changing nature of numerous processes.

One class of theories seeking to explain increased amounts of amyloid-β with aging postulate a gradual failure in mechanisms of clearance, such as immune activity, since the immune system is responsible for removing many forms of unwanted metabolic waste, or filtration of cerebrospinal fluid by the choroid plexus. Alzheimer's becomes a tertiary consequence at the end of a chain of failures that starts with some form of age-related decline in the effectiveness of clearance of metabolic waste in the brain. Cerebrospinal fluid isn't just filtered, however. Small amounts continually drain away from the brain via a variety of small channels in the head, to be replaced by new fluid generated by the choroid plexus. In recent years some researchers have suggested that this drainage is an important mode of clearance for amyloid and tau, and that the necessary channels becomes impaired due to other forms of age-related damage and change. You might look at the efforts of Leucadia Therapeutics, for example, a startup company funded by the Methuselah Foundation, as they work to prove or disprove this mechanism as a cause of Alzheimer's disease. With that in mind, I noticed the following research today, in which the authors offer further evidence in support of the class of hypotheses that involve impaired cerebrospinal fluid drainage.

Study suggests possible new target for treating and preventing Alzheimer's

The new study examined aquaporin-4, a type of membrane protein in the brain. Using brains donated for scientific research, researchers discovered a correlation between the prevalence of aquaporin-4 among older people who did not suffer from Alzheimer's as compared to those who had the disease. Aquaporin-4 is a key part of a brain-wide network of channels, collectively known as the glymphatic system, that permits cerebral-spinal fluid from outside the brain to wash away proteins such as amyloid and tau that build up within the brain. These proteins tend to accumulate in the brains of some people suffering from Alzheimer's, which may play a role in destroying nerve cells in the brain over time.

The study closely examined 79 brains donated through the Oregon Brain Bank. They were separated into three groups: People younger than 60 without a history of neurological disease; people older than 60 with a history of Alzheimer's; and people older than 60 without Alzheimer's. Researchers found that in the brains of younger people and older people without Alzheimer's, the aquaporin-4 protein was well organized, lining the blood vessels of the brain. However within the brains of people with Alzheimer's, the aquaporin-4 protein appeared disorganized, which may reflect an inability of these brains to efficiently clear away wastes like amyloid beta. The study concluded that future research focusing on aquaporin-4 - either through its form or function - may ultimately lead to medication to treat or prevent Alzheimer's disease.

Association of Perivascular Localization of Aquaporin-4 With Cognition and Alzheimer Disease in Aging Brains

Since 2013, we have defined a brain wide perivascular pathway, termed the glymphatic system, that facilitates the recirculation of cerebrospinal fluid (CSF) through the brain parenchyma and supports the clearance of interstitial solutes including amyloid-β (Aβ) and tau. Perivascular exchange of CSF and interstitial fluid is dependent on the astroglial water channel aquaporin-4 (AQP4), which is localized to perivascular astrocytic endfeet that ensheathe the cerebral vasculature. We demonstrated that perivascular CSF recirculation and Aβ clearance are impaired in the aging mouse brain, impairment that was associated with the loss of perivascular AQP4 localization. Prior studies in postmortem human tissue show that AQP4 is up regulated and that localization of AQP4 to the cerebral vasculature is disrupted in the AD cortex. This suggests that age-related mislocalization of AQP4 may slow glymphatic function and promote protein aggregation and neurodegeneration.

In this study, we assessed AQP4 expression and perivascular localization in human brain samples including individuals of different ages and with different cognitive and neuropathological AD profiles. Expression of AQP4 was associated with advancing age among all individuals. Perivascular AQP4 localization was significantly associated with AD status independent of age and was preserved among eldest individuals older than 85 years of age who remained cognitively intact. When controlling for age, loss of perivascular AQP4 localization was associated with increased amyloid-β burden.

Another Group Argues for Alzheimer's Disease to be a Diabetic Condition

A number of the aspects of Alzheimer's disease biochemistry have a strong similarity to aspects of type 2 diabetes biochemistry. Alzheimer's also has the same risk factors, such as the presence of excess visceral fat tissue. Some researchers have gone so far as to call for the classification of Alzheimer's as type 3 diabetes. While not official, there has been enough of this sort of discussion over the years that when type 4 diabetes was discovered it had to be called type 4 in order to avoid the inevitable confusion. It is very unclear as to where the diabetic aspects of Alzheimer's disease fit in the long chain of cause and effect that leads from fundamental damage that causes aging to age-related disease, and so equally unclear as to how effective it can be in the best case to undertake efforts to adjust this biochemistry. Nonetheless, the research linked here is one of many examples in which Alzheimer's has facets that strongly resemble diabetes:

Researchers have found a promising treatment for Alzheimer's disease, by noticing a similarity in the way insulin signaling works in the brain and in the pancreas of diabetic patients. In the pancreas, the Kir6.2 channel blockade increases the insulin signaling, and insulin signaling decreases the blood glucose levels. In the brain, insulin signaling increases the acquisition of memory through CaM kinase II activation by Kir6.2 channel blockade. The research group thus concluded that Alzheimer's disease can be described as a diabetic disorder of the brain. Memantine, a drug widely used to treat Alzheimer's disease, is a well known inhibitor of the N-methyl-D-aspartate (NMDA) receptors that prevent excessive glutamate transmission in the brain. Researchers have now found that memantine also inhibits the ATP-sensitive potassium channel (Kir6.2 channel), improving insulin signal dysfunction in the brain.

In their experiment with mice, the researchers found that memantine treatment improved impaired hippocampal long-term potentiation (LTP) and memory-related behaviors in the mice through the inhibition of KATP channel Kir6.2. "Our results suggest that Kir6.2 blockade in dendritic spines by memantine regulates CaMKII activity by increasing intracellular Ca2+ mobilization, which in turn improves cognitive function by promoting AMPAR trafficking into the postsynaptic membrane. Since KATP channels Kir6.1 or Kir6.2 are critical components of sulfonylurea receptors (SURs) which is downstream insulin receptor signaling, the KATP channel inhibition by Memantine mediates the anti-diabetic drug action in peripheral tissues. And this leads to improved cognitive functions and improved memory retention among Alzheimer's patients." The researchers now hope that results of their study and the parallels drawn with diabetes, will lead to new treatments for Alzheimer's disease, using the inhibition of Kir6.2 channel.

Link: http://www.tohoku.ac.jp/en/press/alzheimers_diabetic_brain_disorder.html

Stem Cell Research and the Treatment of Neurodegenerative Diseases

In this open access review paper, the authors make a case for more human trials in the development of stem cell therapies to treat neurodegenerative diseases. An abundance of caution and heavy regulatory burden drives greater use of animal studies than is perhaps merited given the safety data derived from the first of those studies, which in turn leads to high cost and a high rate of failure in development. A more rapid move to human trials after proving safety in animals is one possible solution to this problem. Another is for large improvements in the quality and cost of on-demand growth of small brain tissue sections that exhibit specific disease characteristics, but even then it is still important to transition to human trials sooner after safety is proven rather than later.

Progress in the field of clinical research and medicine has decreased global mortality drastically. The developed countries have extended the life span of their aging population. However, the modern world is now faced with the issues of aging and age related disorders. Neurodegeneration and neurodegenerative disorders are one of the major health implications faced by the aging population. Neurodegenerative disorders have been thoroughly investigated using animal models, primary cultures, and post mortem human brain tissues. Though informative, these approaches have some limitations. Data obtained from animal models fails to directly correlate with that of humans because a rodent brain is not an exact mimic of a human brain. Despite being highly conserved evolutionarily, mammalian genomes are not identical. Therefore species difference prevents the animal data from successful validation during clinical field trials which poses a severe economic burden. Preclinical studies often do not efficiently translate to the clinic and the clinical trial failures have been reported time and again. Primary culture of neurons is challenging because these are the post mitotic differentiated cells which are difficult to sustain in the in-vitro conditions. Ethical constraints have held back human based research and thus the best possible source of human samples are the postmortem brain tissues. However, these autopsied samples depict the end stages of the disease and do not give much insight into the intricacies of the disease' developing stages. Researchers are not willing to subject the human beings to untested interventions, but the choices have been limited so far.

Majority of neurodegenerative disorders have been incurable (Alzheimer's disease, Parkinson's disease, Huntington's disease, Amyotrophic lateral sclerosis) so far but timely diagnosis can help in the management and symptom alleviation. However, researchers across the world are continuously striving to achieve the cure and hope to achieve fruitful results in the near future. Neurodegeneration studies are largely divided into two major categories. One is the experimental modeling strategy which allows for a comprehensive understanding of the disease such as the etiology, pathophysiology, genotypic-phenotypic interactions, symptomatic, and mechanistic insights. The second is the medical approach which deals with the treatment, therapy, and disease management. Stem cells and iPSCs find widespread application for both, disease modeling as well as transplantation and regenerative therapeutics. In the present review we shall discuss the applicability of stem cell research in the field of neurodegenerative disease modeling and provide the current updates of how stem cell and induced pluripotent stem cell based studies have been employed to address the diagnosis and therapy of the most common neurodegenerative disorders. We shall briefly touch upon the advances and preferable methodologies employing stem cell and iPSC culture such as the three dimensional (3D) culture which has revolutionized the current trend of in-vitro studies. The article intends to highlight the fact, that though animal based in-vivo research is absolutely necessary for the neuroscience research, one cannot wholly and solely depend upon it and human based stem cell driven research has and will open newer avenues for the neurodegenerative disorders′ modeling and treatment.

Link: http://dx.doi.org/10.3389/fmolb.2016.00072

Arguing for Cellular Senescence to be Significant in the Development of Osteoarthritis

There are two ways to provide evidence for a specific cellular mechanism to cause a specific age-related disease. The first, the better method, is to remove, block, or work around the mechanism, while changing as few other variables as possible. This is better because it can lead immediately to the development of a therapy if it turns out that the mechanism in question is important. The worse option is to make the mechanism more active, while changing as few other variables as possible, and see if problems happen more rapidly because of that alteration. This is worse because there is always the risk that greater activity in any biological process does cause greater harm, but is nonetheless not actually relevant to aging and age-related disease because that greater activity never happens in the normal course of matters. DNA repair deficiency is a great example of the type. Significant impairment of DNA repair produces damage, dysfunction, and accelerated disease and mortality, but really isn't all that relevant to normal aging. All that this tells us is that it is important that DNA repair functions correctly, in the same way that it is important to breathe, or important that hearts beat and blood flows. There are many ways to cause damage by breaking the operation of our biochemistry - you can hit living organisms with a hammer, for example - but very few of them tell us much about aging and age-related disease.

With that preamble out of the way, today I'll point you to an interesting open access study in which the authors uses the worse of the two methods noted above to provide evidence for senescent cells to contribute to the development of osteoarthritis, a degenerative condition in which joint tissues become inflamed and break down. This is accomplished by transplanting a sizable number of senescent cells into the joints of mice and observing the outcome over a number of months following the transplant. Senescent cells accumulate in our tissues with age, and their presence is certainly a form of damage, with plenty of evidence to link it to the development of age-related disease. Researchers have produced benefits in laboratory animals by selectively destroying senescent cells, and a variety of these approaches are under development as clinical therapies. Given that, the more conditions linked to cellular senescence, the better off we all are. For this particular study, however, the question is whether or not transplanting senescent cells into tissue is a good enough replication of the processes of aging to tell us something, or whether it is just another sophisticated way of causing damage that isn't particularly relevant to aging. The devil is in the details, but having read the details, I'm leaning towards the former position.

Senescent cells cause harm through signaling. A cell becomes senescent and ceases replication in response to reaching the Hayflick limit, or suffering damage, or finding itself in a toxic environment. Most destroy themselves or are destroyed by the immune system, but some linger. Growing numbers of these cells eventually cause serious harm. A senescent cell secretes a mix of inflammatory and other signals that cause harm to surrounding tissue structures and change the behavior of normal cells for the worse. Perhaps a few percent of all cells in our tissues are senescent by the time we are old, but that is more than enough to cause major dysfunction. Since this is largely a signaling problem, it seems fairly reasonable to suggest that researchers could reproduce the effects of senescent cells on aging via transplantation. This would be something like the reverse of the goal of a stem cell transplant, in which the transplanted cells produce benefits largely through signaling. So long as the number of transplanted senescent cells falls within the bounds of what would be expected over the course of normal aging, one can argue that this type of study can be a good, rapid test of the outcomes that cellular senescence produces. In any case, read the paper and see what you think:

Transplanted Senescent Cells Induce an Osteoarthritis-Like Condition in Mice

Osteoarthritis (OA) is one of the leading causes of pain and disability worldwide. It can greatly increase health care costs and reduce quality of life. The key characteristics of age-related OA in humans include damage of articular cartilage with joint space narrowing and degeneration of soft tissues. Age is the leading predictor for developing OA. However, modeling age- or senescence-associated OA, which may be distinct from injury-related OA, in mice has been challenging. So far, no disease-modifying drug has been approved to treat OA other than pain reducers, partly because etiological mechanisms of age-related OA have been poorly understood to date. Potential cellular mechanisms contributing to the development of OA include low-grade inflammation, chondrocyte alteration, mitochondrial dysfunction, loss of glycosaminoglycans, and dysregulated energy metabolism. In addition, a potential contribution by senescent cells has been suggested. Cellular senescence refers to a state of stable arrest of cell proliferation in replication-competent but apoptosis-resistant cells. Senescent cells accumulate with aging in various tissues, including the articular cartilage. One key feature of senescent cells is secretion of an array of pro-inflammatory cytokines, chemokines, and growth factors, termed the senescence-associated secretory phenotype (SASP). The SASP is observed across a number of senescent cell types, including fibroblasts and mesenchymal stem cells. Although mounting evidence suggests that cellular senescence is associated with OA, whether this link is causal remains to be determined.

To test if senescent cells cause an OA-like arthropathy, we injected either senescent or control nonsenescent fibroblasts into the knee joint region of mice. We transplanted seven mice with control cells and seven with senescent cells. Three months after cell injection, senescent and nonsenescent cell-injected knees were evaluated histologically and radiologically to assess articular cartilage and overall joint structure. We found that the senescent cells induced a phenotype with features resembling OA, including articular cartilage erosion, increased pain, and impaired function. We found that Rotarod performance was significantly decreased in the mice injected with senescent cells compared with animals injected with control nonsenescent cells or those that were not injected. In addition, we found that mice injected with senescent cells moved less and traveled shorter distances than mice injected with control nonsenescent cells. To our knowledge, this is the first evidence suggesting that cellular senescence can actually cause OA. Our findings also imply that targeting senescent cells is a promising approach for preventing or treating OA.

This both provides a new model of OA and implies that clearing senescent cells with senolytics or interfering with their pro-inflammatory SASP could be a disease-modifying therapeutic option. A next step will be to test such interventions in our senescent cell-transplanted model. One of the potential mechanisms by which senescent cells could induce an OA-like phenotype is through the SASP. OA is linked to inflammation and immune cells have been found in early stage OA. IL-6, one of the key SASP components, is highly associated with OA progression. We found that the senescent cells we transplanted secreted 20 times more IL-6 than nonsenescent cells. In addition, senescent cells can directly impair progenitor function through the SASP and spread senescence to nearby cells, both of which might contribute to dysfunction of chondrocytes and therefore to OA.

The finding that cellular senescence can drive development of an OA-like state is consistent with the geroscience hypothesis - that fundamental aging mechanisms, of which cellular senescence is one, predispose to age-related disabilities and chronic diseases, such as OA. If correct, this would imply that senescent cell accumulation may not only predispose to OA, but to multiple other age-related conditions, as is increasingly appearing to be the case. We predict that senolytics or SASP inhibitors such as ruxolitinib, which decreases IL-6 secretion and effects by senescent cells and also alleviates the senescent cell-induced stem cell dysfunction caused by TGFβ-related SASP factors, will delay, prevent, or alleviate OA. Consistent with this possibility, we found that senolytics attenuate age-related loss of glycosaminoglycans, a contributor to developing OA, from the intervertebral discs of progeroid mice. Moreover, senolytics are effective when administered periodically, likely because senescent cells do not of course divide and may be slow to re-accumulate once cleared in the absence of a strong continuing insult. We predict that senolytics may have fewer side effects than the anti-inflammatory agents currently used for controlling pain.

Sarcopenia Finally Obtains an ICD Code

A recent commentary celebrates the granting of an International Classification of Disease (ICD) code to sarcopenia, an important step in the lengthy formal definition of a disease. Sarcopenia is the characteristic age-related decline of muscle mass and strength - though many would say that it only counts as sarcopenia if that decline is significantly greater than normal, and that "normal aging" should not be treated. Hopefully those voices will decline in the years ahead. The carving up of degenerative aging into named conditions is a long, slow, and messy process. It is driven by regulation rather than any sort of common sense goal, as regulators refuse to approve treatments for aspects of aging that are not formally defined as a disease. Thus there is far less funding and interest in those fields, and consequently slow progress. Turning reality into a regulatory definition requires lobbying, extensive debate, and a great deal of money that would be better spent on other things. In the case of sarcopenia, it has taken more than decade of work to get to the point at which the formal definitions of disease start to crystallize into bureaucratic acceptance. So much wasted time.

Sarcopenia has come a long way since Irwin Rosenberg first suggested the term to apply to age-related muscle mass. In 2010, the European Working Group on Sarcopenia defined sarcopenia as low muscle mass together with low muscle function (strength or performance). Subsequently, other international groups developed similar definitions for sarcopenia focusing on walking speed or distance walked in 6 min or grip strength in persons with lean muscle mass. A number of studies have confirmed the validity of these definitions. Based on the available literature, it would appear that sarcopenia is present in 5 to 10% of persons 65 years of age or older. This high quality research approach to sarcopenia has led to the recognition of sarcopenia as a disease entity with the awarding of an ICD-10-CM (M62.84) code in September, 2016. This is an important step similar to the much earlier recognition of osteoporosis as a disease state. This will lead to an accelerated interest in physicians making the diagnosis of sarcopenia and for pharmaceutical companies to accelerate the interest in developing drugs to treat sarcopenia. This research will be helped by there already being a number of biomarkers available for sarcopenia. This should also drive an increase in diagnostic tool availability for recognizing sarcopenia.

Sarcopenia is the most important cause of frailty in older persons. In addition, there is a close association between sarcopenia and bone loss and hip fracture - osteosarcopenia. Sarcopenia has also been found to be a major reason for poor outcomes in persons with diabetes mellitus. SARC-F is a simple screening test for sarcopenia. It prospectively identifies decreased walking speed, activities of daily living disability, hospitalization, and mortality. It has been shown to correlate well with the available international definitions for sarcopenia. There are numerous causes of sarcopenia including anorexia, inflammation, hypogonadism, lack of activity, hypovitaminosis D, motoneuron loss, insulin resistance, poor blood flow to muscle, mitochondrial dysfunction, and genetic causes. The established treatment for sarcopenia is resistance exercise. It appears that sarcopenia is always responsive to resistance exercise. Supplementation with leucine enriched, essential amino acid can also enhance muscle rejuvenation. Vitamin D declines with ageing, and supplementation enhances muscle function when deficient. Testosterone is the drug with the strongest record for increasing muscle mass and improving function. Anamorelin improves muscle mass but not strength. A number of other drugs are under development focusing mainly on myostatin and activin-2 receptor inhibitors. Selective androgen receptor molecules (SARMs) have also shown positive effects. Overall, the availability of an ICD-10 code for those of us who work in the area of muscle wasting disease is a very exciting time. Over the next few years, we can expect major advances in the treatment of older persons with sarcopenia.

Link: http://onlinelibrary.wiley.com/doi/10.1002/jcsm.12147/full

Data on the Effects of Follistatin Gene Therapy from BioViva

Back in 2015, Elizabeth Parrish underwent telomerase and follistatin gene therapy as a part of forming the startup BioViva: a human safety trial of one person, made public as a way to push the bounds of the current debate over when we should get started on human testing of these technologies. Personally, I agree that there is too much talk, too much unnecessary caution and hand-wringing, and not enough action. Sooner rather than later is better, especially given the large amount of animal data showing safety. Parrish is to be congratulated for forging ahead.

The latter of these two gene therapies is more interesting to me, as there is much more evidence in animal studies of the safety and effectiveness of either directly suppressing myostatin or enhancing follistatin to suppress myostatin. This has the effect of increasing muscle mass and reducing fat tissue, along the way tuning the operation of metabolism into a healthier mode of operation. It seems to me to be an enhancement that everyone should undergo, based on the evidence to date: a way to improve health and slow the age-related loss of muscle mass and strength. BioViva has now released some more data on the long term effects of the gene therapies, which show increased muscle mass, reduced fat, and improved aspects of metabolism. In a study of one, this should be taken as an anecdote, especially given that these items can all be changed over the longer term to some degree by lifestyle adjustments. The important thing is that safety has been proven, and that there appear to be benefits is just an added incentive to move to the next step of larger studies and availability of therapy via medical tourism. Hopefully the company will find the funding to achieve both of these goals.

In April 2016 BioViva stated that Elizabeth Parrish, CEO, had experienced telomere lengthening in her leukocytes, as a result of an injection of two experimental therapies. These consisted of a myostatin inhibitor to protect against loss of muscle mass with age, and a telomerase inducer to battle stem cell depletion responsible for diverse age-related diseases and infirmities. While the test was designed to establish the first human safety data regarding telomerase induction, in tests conducted by SpectraCell Laboratories, data indicated that her leukocyte telomeres had lengthened by approximately 20 years, from 6.71kb to 7.33kb. Further data will be released later this year. Upon further examination and testing, comparison of Parrish's data prior to the therapy and following the therapy has revealed additional positive changes. MRI scans taken before and after depict a slight increase in muscle size in conjunction with a noticeable reduction in muscle fat content. An over-accumulation of intramuscular fat, also known as 'marbling', is associated with increased insulin resistance, and as such an appropriate reduction may be linked to beneficial metabolic changes, in addition to the improved musculature. The aforementioned patient's total body weight has also not decreased during this period, and as such weight loss is not a confounding variable. The muscle growth achieved post-therapy corresponds with observed improvements in patients with Becker's Muscular Dystrophy, after receipt of myostatin inhibition gene therapy.

Researchers have noted that a significant reduction in fasting glucose was apparent in mice following telomerase gene therapy. The subject's fasting glucose has declined from previous measurements of 94 mg/dL and 86 mg/dL, to a fasting glucose level of 71 mg/dL by August 2016, as measured by Quest Diagnostics. Repeated testing will confirm the implied increase in insulin sensitivity. Previous research has also indicated that telomerase deficiency impairs glucose metabolism and insulin secretion in telomerase deficient mice, which may explain an apparent improvement in metabolic markers. In accordance with an improvement in metabolic health, triglyceride levels have also declined from 140 mg/dL in 2015 prior to the therapy, to 36 mg/dL in February 2016, subsequently rising to 80 and 84 mg/dL in August 2016. While there has been an increase in blood triglyceride content following the February reading, it is still measurably lower than before treatment. Both decreases in fasting glucose and triglycerides can be potentially explained by prior studies, of both telomerase and myostatin. Raised myostatin mRNA seen in type 2 diabetes patients is associated with impaired insulin sensitivity, raising triglyceride levels and low-grade chronic inflammation. Myostatin inhibition in mice has also been shown to reduce triglyceride levels and improve insulin sensitivity.

No negative effects have been reported, and there are no visible detrimental effects in blood analysis thus far; providing tentative evidence of safety in the first human test of BioViva's dual gene therapy strategy.

Link: http://bioviva-science.com/blog/dual-gene-therapy-has-beneficial-effects-on-blood-biomarkers-and-muscle-composition