Adding to the mounting evidence that your intestinal flora is crucial to good health, a new study shows that altering communities of gut bacteria may actually help you live longer.

To date, countless papers on metabolism, longevity, and age-related disease have arrived at the same conclusion: A balanced gut flora is a happy gut flora. However, few research efforts have offered a convincing explanation why gut bacteria tend to lose this important balance over time. Dr. Heinrich Jasper, lead author of the current study, said in a press release that the new findings establish a kind of systemic framework through which this so-called “deregulation” of gut bacteria can be understood — and, consequently, reversed.

“Our study explores age-related changes in the gut that include increased oxidative stress, inflammation, impaired efficiency of the immune response, and the over-proliferation of stem cells," he said. "It puts these changes into a hierarchical, causal relationship and highlights the points where we can intervene to rescue the negative results of microbial imbalance."

For the study, the lab observed this process in the intestines of Drosophilia, or fruit flies. They found that the so-called bacterial load increased as the fly aged, unraveling the symbiotic relationship between the microorganisms and the absorptive cells lining its guts. The resulting imbalance, which over time triggered an inflammatory response, was shown to be the result of an overzealous stress gene called FOXO.

By examining the inflammatory chain reaction triggered by this gene, Jasper and colleagues were able to pinpoint the problem: the chronic suppression of PGRP-SC, a class of molecules that regulate immune response to bacteria. Using gene therapy to restore the expression of these important molecules, the team was able to prevent the imbalance from occurring in the first place. As a result, the fly’s lifespan increased. "If we can understand how aging affects our commensal [symbiotic] population — first in the fly and then in humans — our data suggest that we should be able to impact health span and life span quite strongly because it is the management of the commensal population that is critical to the health of the organism,” Jasper explained.

Gut Bacteria and Your Health

The current study recalls a number of previous attempts to quantify the influence of microbial balance and regulation on a person’s overall health. Another example is an Italian study from earlier this year in which researchers show that probiotics can have a tremendous impact on a newborn’s gastrointestinal defense. Other studies have pointed to a similar connection between gut bacteria and colorectal cancer, rheumatoid arthritis, and even autism.

Dr. David Schneider, a Stanford University professor of microbiology and immunology who was not involved in the current study, said in an email to Medical Daily that the new findings represent an important step toward a clinical application of these discoveries. “This research tells those working on human guts that they should consider targeting negative regulatory loops as a way leads to maintenance of conventional gut microbes,” he wrote. “Unfortunately, this is something that we seldom measure and don’t yet know how to manipulate well. This work provides another example that we should be paying close attention to the state of our guts.”



Source: Guo L, Karpac J, Tran SL, Jasper H. PGRP-SC2 Promotes Gut Immune Homeostasis to Limit Commensal Dysbiosis and Extend Lifespan. Cell. 2014.