Gut Bacterium Linked to Depression Through Inflammatory Molecule

Researchers at Harvard Medical School have identified a mechanism connecting a common gut bacterium to depression. The bacterium, *Morganella morganii*, can produce a molecule that triggers inflammation. This process may contribute to major depressive disorder.

This discovery offers a clearer understanding of how gut microbes can influence brain health. The researchers found that an environmental contaminant, diethanolamine (DEA), plays a key role. DEA can alter a molecule produced by *M. morganii*.

The altered molecule activates the immune system. This activation leads to the release of inflammatory proteins called cytokines, specifically interleukin-6 (IL-6). Chronic inflammation is associated with major depressive disorder.

DEA is present in many industrial, agricultural, and consumer products. The researchers suggest that DEA could serve as a biomarker for certain types of depression. The findings also indicate that some forms of depression may involve the immune system. This opens possibilities for new treatments targeting immune responses.

This study was a collaboration between the lab of Jon Clardy, which focuses on bacterial small molecules, and the lab of Ramnik Xavier, which studies microbiome effects on health. Their combined expertise advanced the understanding of gut bacteria interactions with the immune system.

Previous research has linked *M. morganii* to inflammatory conditions like type two diabetes and inflammatory bowel disease. The new findings were published in the *Journal of the American Chemical Society*.