Hepatoprotective mechanism of tauroursodeoxycholic acid and its therapeutic potential in liver diseases

Tauroursodeoxycholic acid (TUDCA) is a natural hydrophilic secondary bile acid that acts as an effective chemical chaperone and exerts dramatically hepatoprotective effects. It alleviates endoplasmic reticulum stress (ERS), regulates the unfolded protein response (UPR), suppresses inflammatory responses, reduces oxidative stress, and inhibits hepatocyte apoptosis. In addition, TUDCA maintains bile acid metabolism homeostasis and modulates the gut–liver axis, showing significant therapeutic potential in multiple liver disorders, including metabolic dysfunction-associated steatotic liver disease (MASLD), cholestatic liver injury, liver fibrosis, hepatocellular carcinoma (HCC), hepatic ischemia–reperfusion injury (IRI). Despite promising preclinical evidence, the specific crosstalk between TUDCA and the gut microbiota remains largely unclear, and high-quality clinical evidence supporting its translation into clinical practice is still limited. This narrative review summarises the molecular targets and signaling pathways of TUDCA, discusses current research gaps, and provides a theoretical foundation for its rational clinical application and future mechanistic studies.