Gut commensals-derived succinate impels colonic inflammation in ulcerative colitis.

Gut microbiota-derived metabolites play a crucial role in modulating the inflammatory response in inflammatory bowel disease (IBD). In this study, we identify gut microbiota-derived succinate as a driver of inflammation in ulcerative colitis (UC) by activating succinate-responsive, colitogenic helper T (Th) cells that secrete interleukin (IL)-9. We demonstrate that colitis is associated with an increase in succinate-producing gut bacteria and decrease in succinate-metabolizing gut bacteria. Similarly, UC patients exhibit elevated levels of succinate-producing gut bacteria and luminal succinate. Intestinal colonization by succinate-producing gut bacteria or increased succinate availability, exacerbates colonic inflammation by activating colitogenic Th9 cells. In contrast, intestinal colonization by succinate-metabolizing gut bacteria, blocking succinate receptor signaling with an antagonist, or neutralizing IL-9 with an anti-IL-9 antibody alleviates inflammation by reducing colitogenic Th9 cells. Our findings underscore the role of gut microbiota-derived succinate in driving colitogenic Th9 cells and suggesting its potential as a therapeutic target for treating IBD.