Fecal metabolomics in Crohn's disease reveal N-Acetylglutamine as a Th17/Treg modulator

The gut microbiota is widely recognized as a key component in the pathogenesis of inflammatory bowel disease (IBD), and one of its primary modes of interaction with the host occurs via metabolites. Studies have confirmed that gut microbiota dysbiosis affects immune maturation, immune homeostasis, host energy metabolism, and the maintenance of mucosal integrity. However, the specific metabolites that influence the differentiation of mucosal CD4⁺ T cells remain insufficiently elucidated. This study aimed to identify and validate unknown metabolites capable of affecting the differentiation of CD4⁺ T cell subsets by characterizing changes in fecal metabolites between IBD patients and non-IBD controls. Using untargeted metabolomics, we quantitatively detected a total of 1480 metabolites in positive ion mode and 1178 metabolites in negative ion mode. Regression analysis results showed that N-Acetylglutamine was significantly downregulated in IBD patients and was identified as a key differential metabolite. Further in vitro functional experiments confirmed that this metabolite could directly regulate the differentiation balance of CD4⁺ T cells, specifically inhibiting the differentiation of pathogenic Th17 (pTh17) cells while promoting the generation of Treg. This study verifies the critical role of the metabolite N-Acetylglutamine in regulating the Treg/pTh17 cell balance, providing a theoretical basis for its potential as a therapeutic target for IBD.