Background: Autoimmune hepatitis (AIH) is a chronic immune-mediated liver disease with an incompletely understood etiology. Observational studies suggest dysregulated immunity, but confounding and reverse causation have hindered causal inference. Mendelian randomization (MR) uses genetic variants as instrumental variables to assess causality and has recently been applied to investigate immune involvement in AIH.
Objective: To summarize and interpret findings from a recent bidirectional two-sample MR study evaluating the causal effects of 731 immune cell traits on AIH risk, contextualizing them within existing immunological knowledge.
Methods: This narrative review focuses on a key MR investigation using genome-wide association study (GWAS) summary statistics for 731 immunophenotypes and AIH. The primary analysis method was inverse variance weighting, supplemented by sensitivity analyses (MR-Egger, weighted median) and reverse MR to assess robustness and directionality of causal relationships.
Conclusion: The MR analysis provides genetic evidence supporting a causal role for specific innate and adaptive immune cell subsets in AIH pathogenesis. These findings highlight the therapeutic potential of targeting pathways involving myeloid-derived suppressor cells (MDSCs), regulatory T cells (Tregs), dendritic cells, NKT cells, and the PD-1/PD-L1 axis, offering a foundation for future mechanistic and translational research.