Research progress on the role of gut microbiota dysbiosis in the pathogenesis of immune-mediated liver diseases.

Gut microbiota dysbiosis plays a significant role in the pathogenesis of immune-mediated liver diseases (IMLDs), including autoimmune hepatitis (AIH), primary biliary cholangitis (PBC), and primary sclerosing cholangitis (PSC), through multiple gut-liver axis mechanisms. Microbial metabolites such as short-chain fatty acids (SCFAs) and secondary bile acids regulate hepatic immune homeostasis by activating G protein-coupled receptors (GPRs) and the farnesoid X receptor (FXR). Concurrently, disruption of the intestinal barrier integrity allows endotoxins (e.g., lipopolysaccharide) to activate hepatic macrophages via the TLR4/NF-κB pathway, triggering a pro-inflammatory cytokine cascade. Studies indicate an enrichment of Veillonella in AIH patients, while PBC patients display elevated Enterobacteriaceae and reduced Oscillospira spp. PSC is characterized by Klebsiella pneumoniae translocation and Candida albicans toxin-mediated injury. Therapeutic strategies such as fecal microbiota transplantation (FMT), probiotics, prebiotics, and bacteriophages therapy have shown efficacy in clinical settings, underscoring the potential of targeting the gut microbiota for managing IMLDs. Future research should integrate immune cell regulation by gut-derived factors and develop precision therapies based on the gut-liver axis.