Study Suggests Gut Health Can Ward Off Illness

New research published in the journal Cell has identified a population of gut microbes that modulates immune response to ward off viral invaders. The type and diversity of microbes in the gut contribute to the strength and health of the microbiome which contributes to overall health, as well as the body’s ability to ward off illness.

Researchers identified one specific microbe that creates a chain reaction in the immune system’s protection against invasive viruses. This microbe, Bacteroides fragilis (B. fragilis)­, contains a molecule on its surface that recognizes differences in the external structures of normal human cells versus infectious organisms. When an infectious organism is discovered, the molecule signals to cells in the colon to release a protein called interferon-beta. Interferon-beta then kills off infected cells while inciting other immune cells to attack the virus itself.

One study found that the molecule present on B. fragilis that initiates this immune signaling cascade has also been found on other gut bacteria within the microbiome. Researchers demonstrated that these other gut bacteria containing the surface protein could trigger similar immune signaling, creating a broader immune protection system.

The study also examined the protective effects of B. fragilis in two groups of mice—one which had been given antibiotics to deplete their microbiota, and one with their gut microbiota intact. The mice that had been given antibiotics were more likely to develop active, and more severe, infections than those with healthy microbiota. It was also discovered that when mice with depleted microbiota were given B. fragilis in their drinking water, they had much milder infections, suggesting that diet can directly strengthen immune protection when containing certain microbes.

While a variety of factors can influence the health of the microbiome, the identification of specific microbes that play a key role in immune system signaling, along with the demonstration that these microbes can be supplemented through diet to depleted animal microbiomes, presents foundational research in the future enhancement of the human immune system.