Longevity & AgingYour Immune System Acts as Microbiome Traffic Cop — and Aging Breaks This
New research published in PLOS Biology proposes that the immune system doesn't just tolerate gut microbes — it actively polices them. Scientists suggest that immune surveillance monitors microbial population growth, suppressing any single species that starts to dominate, thereby preserving diversity. As we age, immune function declines (immunosenescence), loosening this control and allowing certain microbes to overgrow while others disappear. This shift — called dysbiosis — is linked to metabolic disease, inflammation, and reduced lifespan. The model reframes microbiome diversity not as a fixed trait but as a dynamic balance maintained by ongoing immune activity. When that balance breaks down with age, it contributes to the chronic low-grade inflammation known as inflammaging, creating a feedback loop that accelerates health decline.
