In recent years, a great deal of attention has been devoted to the role of the gut microbiome in aging, as populations shift to include fewer helpful and more harmful microbes. In particular, the ability of the gut microbiome to influence the state of chronic inflammation in aging may be at least as important as lifestyle choices such as degree of exercise. Expanding this line of thinking, researchers here look at the macrobiome, small parasitic animals that dwell in the gut, and their role in age-related inflammation.
A new review looks at the growing evidence to suggest that losing our 'old friend' helminth parasites, which used to live relatively harmlessly in our bodies, can cause ageing-associated inflammation. It raises the possibility that carefully controlled, restorative helminth treatments could prevent ageing and protect against diseases such as heart disease and dementia. "A decline in exposure to commensal microbes and gut helminths in developed countries has been linked to increased prevalence of allergic and autoimmune inflammatory disorders - the so-called 'old friends hypothesis'. A further possibility is that this loss of 'old friend' microbes and helminths increases the sterile, ageing-associated inflammation known as inflammageing."
Helminths have infected humans throughout our evolutionary history, and as a result have become master manipulators of our immune response. Humans, in turn, have evolved levels of tolerance to their presence. The loss of helminths has so far been linked to a range of inflammatory diseases, including asthma, atopic eczema, inflammatory bowel disease, multiple sclerosis, rheumatoid arthritis, and diabetes. Some studies have shown that natural infection with helminths can alleviate disease symptoms, for example in multiple sclerosis and eczema, while other studies in animal models suggest that intentional infection with helminths could have benefits against disease.
The safer, and perhaps more palatable, option is the concept of using helminth-derived proteins to achieve the same therapeutic benefits. This was tested recently in mice and shown to prevent the age-related decline in gut barrier integrity usually seen with a high-calorie diet. It also had beneficial effects on fat tissue, which is known to be a major source of inflammageing. The authors speculate that if helminths have anti-inflammageing properties, you would expect to see lower rates of inflammageing-related disease in areas where helminth infection is more common. There is some evidence to support this. "In the wake of successes during the last century in eliminating the evil of helminths, the time now seems right to further explore their possible benefits, particularly for our ageing population - strange as this may sound."