Gut microbiota-bile acid-immune axis: receptor signaling, metabolic regulation, and therapeutic translation

The gut microbiota and bile acid metabolism are intricately linked, forming a pivotal axis that regulates host immune function and metabolic homeostasis. Bile acids not only facilitate lipid digestion as surfactants but also act as key signaling molecules by activating multiple receptors, which modulate immune responses, energy metabolism, and inflammatory processes. The gut microbiota enzymatically converts primary bile acids into secondary bile acids, thereby influencing the composition and function of the bile acid pool. Dysbiosis of the gut microbiota and aberrations in bile acid signaling pathways are closely associated with various diseases. Recently, therapeutic strategies targeting the gut microbiota-bile acid-immune axis have emerged, including receptor agonists/antagonists and microbiota modulators, offering novel approaches for disease prevention and treatment. This review comprehensively summarizes the molecular mechanisms, receptor signaling pathways, metabolic regulation, and clinical translational potential of this axis, aiming to provide theoretical support for future precision medicine and innovative therapeutic strategies.