IL-33/ST2 enhances MMP-12 expression by macrophages to mediate inflammatory and immune response in IgG4-Related Ophthalmic Disease.

IgG4-Related Ophthalmic Disease (IgG4-ROD) is a chronic autoimmune-mediated fibrotic disease that predominantly affects the lacrimal glands, often leading to loss of function in the involved tissues or organs. Recent studies have demonstrated that MMP-12 is highly expressed in IgG4-ROD and plays a significant role in regulating immune responses. In this study, we reviewed nine patients diagnosed with IgG4-ROD based on clinical manifestations and histological analysis, and we investigated the expression of IL-33/ST2 and MMP-12 in IgG4-ROD lacrimal gland tissues using IHC. We found that IL-33 interacts with its specific receptor ST2, both of which are significantly overexpressed in IgG4-ROD tissues. Additionally, we successfully constructed a mouse model by introducing the Lat mutation into C57BL/6 mice to mimic IgG4-ROD lacrimal gland involvement, which helped elucidate the mechanisms involved in the induction of MMP-12. Furthermore, immunofluorescence staining confirmed that most MMP-12 cells were derived from M2 macrophages, and an ELISA assay demonstrated that IL-33 upregulates MMP-12 in IgG4-ROD. Collectively, these data suggest that the IL-33/ST2/MMP-12 signaling pathway is activated in IgG4-ROD, with IL-33/ST2 potentially promoting M2 macrophage polarization and activation to produce MMP-12, which may serve as a novel therapeutic target for IgG4-ROD.