Nutritional supplement Youtianli regulates Treg function and gut immunity via SCFA-producing microbiota modulation

Gut microbiota plays a vital role in immune regulation by producing short-chain fatty acids (SCFAs), which influence regulatory T cells (Tregs) and maintain immune balance. Disruptions in the SCFAs-Tregs axis contribute to immune dysregulation and inflammation. This study explores the immunomodulatory effects of the nutritional supplement Youtianli (YTL) in a juvenile mouse model of lipopolysaccharide (LPS)-induced immune dysregulation. YTL supplementation significantly reduced pro-inflammatory cytokines, restored Th17/Treg balance, and increased SCFA-producing bacteria. Metabolomic analysis confirmed upregulation of butyrate and propionate metabolism, essential for immune modulation. Fecal microbiota transplantation (FMT) demonstrated that immunoregulatory effects of YTL were microbiota-dependent. These findings suggest that YTL improves immune function by modulating gut microbiota and enhancing SCFA metabolism. This study highlights the potential of YTL as an immunoregulatory supplement and encourages further research into microbiota-targeted nutritional interventions. Schematic of the molecular mechanism by which YTL supplementation modulates treg cell function via gut microbiota and SCFAs.