Grant-in-Aid for Scientific Research(C)，2026.04 - 2029.03

Grant-in-Aid for Scientific Research(C)，2022.04 - 2025.03，The specific mechanism of fibrosis in IgG4-related sialadenitis

IgG4-related sialadenitis (IgG4-SA) is a subtype of IgG4-related disease, characterized by dense lymphoplasmacytic infiltration and fibrosis. This study investigated the role of plasma cells in fibrosis development in IgG4-SA. Histological and immunohistochemical analyses revealed abundant secondary lymphoid follicles surrounded by collagen fibers. Type I collagen was predominant away from follicles, while type III collagen and FAP+ fibroblasts were concentrated nearby. Spatial analysis showed 90.4% of MUM1+ plasma cells located within 20μm of FAP+ fibroblasts. Immunofluorescence demonstrated MUM1+ cells expressed PDGFβ, and FAP+ fibroblasts expressed PDGFRβ and pSTAT3. These findings suggest plasma cells promote fibrosis in IgG4-SA via PDGF/PDGFR signaling.