m7G Modification and Immune Infiltration Profiles in Primary Sclerosing Cholangitis

Background: To explore the contribution of N7-methylguanosine (m 7 G) RNA modification to immune dysregulation in primary sclerosing cholangitis (PSC) and identify potential diagnostic biomarkers. Methods: Transcriptomic data (GSE177044) from peripheral blood mononuclear cells of 220 PSC patients and 320 controls were analyzed for 29 m 7 G-related genes. Differential expression and three unsupervised clustering strategies (m 7 G, gene, and m 7 G-score) defined molecular subtypes. A machine learning-based nomogram was constructed using m 7 G feature genes. Validation included immunohistochemistry (IHC) on liver tissues from 11 PSC patients and multiplex immunofluorescence (mIF) to assess EIF4E3 co-localization with immune cell markers. Results: Twenty m 7 G-related differentially expressed genes (DEGs) were identified between PSC and controls. Unsupervised clustering revealed two m 7 G clusters. DEGs between them defined two gene clusters. Patients were further stratified by m 7 G scores. m 7 G cluster A and gene cluster B exhibited similar immune infiltration patterns, characterized by enrichment of macrophages, T-lymphocytes, myeloid-derived suppressor cells, and pathways related to infection and tumor transformation. Both clusters were associated with elevated m 7 G scores. Eight m 7 G-related DEGs ( NSUN2, EIF4G3, EIF4E3, EIF3D, AGO2, LSM1, DCPS, and DCP2 ) were prioritized to construct a nomogram model for PSC risk prediction. EIF4E3 was identified as the top immune-associated gene. IHC confirmed portal tract-specific overexpression of all feature genes in PSC livers. IF revealed dense infiltration of myeloid and cytotoxic cells. mIF showed EIF4E3 co-localization with CD11b⁺, CD66b⁺, CD68⁺, CD8⁺, and CD56⁺ cells within portal areas. Conclusion: m 7 G RNA modification contributes to immune dysregulation in PSC. The eight-gene signature and nomogram provide a preliminary tool for clinical risk stratification.