L. acidophilus prevents cholesterol gallstones in mice by regulating gut microbiota-mediated BAs metabolism and cholesterol homeostasis

Probiotic with established metabolic benefits, has shown potential in cholesterol regulation, yet its protective mechanisms against CGS remain unclear. This study investigated the effects of L. acidophilus supplementation on high-fat diet-induced CGS in C57BL/6 J mice. L. acidophilus intervention ameliorated lipid metabolic dysregulation and hepatic dysfunction, enriching beneficial bacteria ( Akkermansia muciniphila, Muribaculum intestinale ), and suppressing Desulfovibrio . LC-MS/MS analysis showed altered bile acid profiles with increased fecal TC and TG excretion. Mechanistically, L. acidophilus activated intestinal FXR-FGF15 signaling, suppressing hepatic CYP7A1 expression and reducing bile acid synthesis. It also enhanced transintestinal cholesterol excretion (TICE) via ABCG5/8 upregulation and inhibited hepatic cholesterol biosynthesis through SREBP2-HMGCR pathway suppression. Importantly, L. acidophilus attenuated inflammation by reducing intestinal and serum levels of LPS, diminishing pro-inflammatory cytokines including TNF-α, IL-1β, and IL-6, meanwhile enhancing gut barrier function via promoting tight junction protein expression. These findings demonstrate that L. acidophilus prevents CGS through coordinated regulation of gut microbiota, bile acid homeostasis, cholesterol metabolism, and inflammatory responses, supporting its potential as a functional food or probiotic supplement for CGS prevention in high-risk populations. • L. acidophilus reduces gallstone incidence caused by high-fat diet in mice. • L. acidophilus restores high-fat diet-induced gut microbiota dysbiosis in mice. • L. acidophilus regulates bile acid and cholesterol metabolism to reduce gallstone incidence.