GZMK Facilitates Experimental Rheumatoid Arthritis Progression by Interacting with CCL5 and Activating the ERK Signaling.

Synovial over-proliferation is a key event in the progression of rheumatoid arthritis (RA) disease. Ferroptosis may be essential for maintaining the balance between synovial proliferation and death. This study aimed to investigate the molecular mechanisms mediating the activation and ferroptosis of collagen-induced arthritis (CIA)-synovial fibroblasts (SFs). Differentially expressed genes (DEGs) in the synovial tissues of CIA rats and normal rats were screened through sequencing. The GSE115662 dataset from the GEO database was analyzed and screened for DEGs. The viability, proliferation, migration, invasion, cell cycle, and apoptosis of CIA-SFs were analyzed by cell counting kit-8, 5-ethynyl-2'-deoxyuridine, flow cytometry, transwell migration, and invasion assays. The ferroptosis of CIA-SFs was assessed using matching reagent kits to detect indicators like reactive oxygen species, ferrous iron, malondialdehyde, glutathione, and superoxide dismutase. The interaction between Granzyme K (GZMK) and C-C motif chemokine 5 (CCL5) was determined by coimmunoprecipitation assay. We found abnormal GZMK expression in the GSE115662 database and mRNA sequencing data. GZMK was overexpressed in CIA-SFs, and GZMK promoted cell proliferation, migration, invasion, inflammation, and decreased cell apoptosis and ferroptosis in CIA-SFs. GZMK could interact with CCL5 to activate the ERK signaling. GZMK and CCL5 knockdown improved by reducing arthritis scores, redness and swelling of paws, and pathological changes in joint synovium of CIA rats. CCL5 overexpression reversed the effects of GZMK silencing on CIA-SFs cell proliferation, migration, invasion, apoptosis, and ferroptosis. We confirmed that GZMK accelerated experimental rheumatoid arthritis progression by interacting with CCL5 and activating the ERK signaling.