Scientists have identified several hallmarks of aging – observable biological patterns of dysfunction that occur as an organism ages. These hallmarks both drive and are the result of inflammaging, the chronic, low-grade inflammation that occurs with aging. Findings from a recent study suggest that fecal microbial transplants reverse the hallmarks of aging.

As a person ages, the overall makeup of the population of microbes that inhabit their gut undergoes extensive changes. These changes are associated with increased inflammation, altered metabolic health and immune function, and an increased risk of chronic disease. Fecal microbial transplant is a therapeutic strategy that involves transfer of microbial-rich feces from a donor to a recipient. The goal of fecal microbial transplant is to restore the microbial balance in the gut of the recipient as a means to improve health.

The investigators performed fecal microbial transplants first between young mice and aged mice and then vice versa. They sequenced the bacterial populations in the fecal samples before and after transplantation. Then they assessed the effects of the transplants on inflammatory hallmarks of aging (specifically, protein levels, immune function, and behavior).

They found that fecal microbial transplantation from aged to young mice elevated systemic and tissue markers of inflammaging, accelerated age-related inflammation in the central nervous system and retina, drove the loss of key functional proteins in the retina, and promoted intestinal barrier permeability (sometimes referred to as “leaky gut”). However, transplantation from young to old mice reversed these effects.

These findings suggest that age-related changes in the gut microbiota promote inflammation, driving increased gut permeability, retina dysfunction, and impaired brain health, and contributing to the hallmarks of aging. Learn more about the hallmarks of aging in our comprehensive overview article.

• View full publication.