Mechanism Study on Lactobacillus acidophilus Inhibiting Cholesterol Gallstone Formation by Regulating FXR-TLR4/NF-κB Pathway and Intestinal Barrier Function

Objective: In this study, a mouse model of cholesterol gallstones was established, and interventions with Lactobacillus acidophilus were administered.The research verified that Lactobacillus acidophilus improves intestinal barrier function through the hepatic FXR-TLR4/NF-κB pathway, and explored its mechanism of action in inhibiting cholesterol gallstone formation. Methods :We procured 30 male C57BL/6J mice at 8 weeks of age. After seven days of adaptation on standard rodent diet, animals underwent randomization into three cohorts: controls fed regular chow and saline control group(ND group, n =10), the lithogenic diet and saline c ontrol group (HFD group, n =10) , and the lithogenic diet and Lactobacillus acidophilus intervention group(HFLA group, n =10).Mice in the ND and HFD groups were gavaged with saline, while those in the HFLA group received Lactobacillus acidophilus by gavage, one time per day across 8 consecutive weeks. Body weight was monitored weekly.After 8 weeks, mice were sacrificed.Serum was collected to measure levels of LPS, IL-6, and TNF-α. Gallbladder stone formation was scored, Gallbladder specimens underwent hematoxylin-eosin staining to assess histopathological changes. Hepatic samples were processed via Western blotting to quantify TLR4 and phosphorylated NF-κB P65 proteins. Intestinal tissues were collected to measure mRNA expression levels of FXR、ZO-1, Occludin, and Claudin. Results: L. acidophilus intervention attenuated body weight accumulation ( P < 0.05) and reduced stone formation indices relative to HFD controls; improved gallbladder inflammation in pathological findings;increased mRNA expression of MUC5AC ( P <0.01); decreased mRNA and protein expression of hepatic TLR4, NF-κB P65; reduced serum levels of LPS, IL-6, and TNF-α ( P <0.01) ; and significantly increased expression of colonic ZO-1, Occludin, and Claudin ( P <0.01). Conclusion: Lactobacillus acidophilus significantly reduces lithogenic diet-induced gallstone scores.It upregulates illeal FXR activity to inhibit NF-κB P65-mediated inflammation and improves intestinal barrier function to reduce LPS entry into the bloodstream.These dual effects work together to alleviate gallbladder mucosal inflammation and excessive MUC5AC secretion, thereby inhibiting cholesterol gallstone formation.This study provides new theoretical basis and potential therapeutic targets for probiotic-based prevention and treatment of cholesterol gallstones.