Bifidobacterium animalis subsp. lactis 832 Alleviates DSS-Induced Colitis in a Murine Model by Regulating Gut Microbiota and Phospholipid Metabolism

Inflammatory bowel disease (IBD) is a chronic intestinal disorder with recurrent inflammation for which effective therapeutic options remain limited. Probiotics from the Bifidobacterium genus have potential beneficial effects on the prevention of IBD by improving intestinal barrier integrity and modulating immune responses. However, whether these effects are mediated by the regulation of gut metabolism remains largely unclear. This study was designed to explore the protective effect of an infant-derived Bifidobacterium animalis subsp. lactis 832 (B. lactis 832) on dextran sulfate sodium (DSS)-induced colitis in mice and its underlying mechanism. B. lactis 832 treatment significantly alleviated colitis severity (p < 0.05), as evidenced by reduced weight loss, disease activity index (DAI), and colonic injury, accompanied by significantly decreased pro-inflammatory cytokine expression and increased Il10 expression (p < 0.05). It also improved intestinal barrier integrity and modulated gut microbiota composition by reducing potentially pathogenic bacteria while enriching beneficial taxa. Surprisingly, metabolomic analysis revealed that B. lactis 832 intervention enhanced intestinal phospholipid metabolism, particularly increasing phosphatidylethanolamine (PE) and phosphatidylcholine (PC) levels. Notably, PE or PC supplementation recapitulated the protective effects against DSS-induced colitis (p < 0.05). These findings suggest that B. lactis 832 alleviates colitis through microbiota-associated metabolic regulation, highlighting a key role for phospholipid metabolism in mediating probiotic effects.