The bile acid-gut microbiota-vitamin D axis: new insights into biliary atresia.

Biliary atresia (BA) is a progressive fibroinflammatory disease affecting both intrahepatic and extrahepatic bile ducts. It leads to cholestasis, hepatic fibrosis, and eventually biliary cirrhosis. Although BA is the most common cause of neonatal cholestasis, its exact pathogenesis remains incompletely understood. Emerging evidence suggests that disturbances in bile acid metabolism, gut microbiota dysbiosis, and vitamin D deficiency may play critical roles in the initiation and progression of BA. This review systematically summarizes the dynamic evolution characteristics of bile acid profiles, gut microbiota composition, and vitamin D levels in children with BA across different disease stages. It further explores the potential positive feedback loop effects of the bile acid-gut microbiota-vitamin D axis in the pathogenesis and progression of the disease. Additionally, this review discusses potential diagnostic value and therapeutic strategies based on this axis. Interventions targeting bile acid metabolism, modulating the gut microbiota, and supplementing vitamin D have shown promise in altering the disease course. Despite these advances, further research is needed to elucidate the precise molecular mechanisms underlying this axis in BA. Such knowledge will pave the way for more effective preventive and therapeutic strategies for this complex disease.