Microbial metabolite indole-3-propionic acid drives mitochondrial respiration in CD4(+) T cells to confer protection against intestinal inflammation.

The gut microbiota and its metabolites critically regulate immune cell phenotype, function and energy metabolism. We screened a collection of gut microbiota-related metabolites to identify modulators of mitochondrial metabolism in T cells. Here we show that indole-3-propionic acid (IPA) stimulates mitochondrial respiration of CD4(+) T cells by increasing fatty acid oxidation (FAO) and amino acid oxidation (AAO), while inhibiting glycolytic capacity. IPA also impacts CD4(+) T cell behaviour by inhibiting their differentiation to type 1 and type 17 helper T cell phenotypes. Mechanistically, the metabolic and immune effects of IPA are mediated by peroxisome proliferator-activated receptor-β/δ. The administration of IPA rescues mitochondria respiration in mice with gut bacteria depletion or colitis by enhancing FAO and AAO in colonic CD4(+) T cells. Adoptive transfer experiments show that IPA acts on CD4(+) T cells to exert its protective effect against inflammation. Collectively, our study reveals that the anti-inflammatory effects of IPA are mediated by metabolic reprogramming of CD4(+) T cells toward the enhancement of mitochondrial respiration.