Scientists discover how gut bacteria “train” the intestine to fight inflammation

A Northwestern Medicine study published in Nature Communications reveals that a substance produced by gut bacteria when they digest dietary fiber may leave a lasting molecular imprint on intestinal cells. This imprint seems to foster immune tolerance, potentially protecting against inflammatory bowel disease-like conditions even after the metabolite's influence has ceased.

The research, led by Yingzi Cong, PhD, and Tianming Yu, PhD, was conducted on mice and found that butyrate, a short-chain fatty acid, induces a persistent immunoregulatory response in the intestine. This response is characterized by increased production of IL-10, an anti-inflammatory cytokine, in CD4+ T-cells and provides protection from intestinal inflammation even after butyrate treatment is discontinued.

The effect was also observed in germ-free mice, indicating that butyrate can establish a lasting intestinal environment independent of continuous microbial stimulation. The study also identified N1-acetylspermidine as a key metabolite carrying the signal, produced by intestinal epithelial cells (IECs) after butyrate treatment. This suggests that IECs, typically seen as short-lived barriers, may retain a lasting molecular record of beneficial signals from the microbiome.

The research could have implications for inflammatory bowel disease, with further studies planned to explore the pathway in human intestinal disease and investigate other metabolites that may contribute to the effect.