Blockade of IL-17 alleviated inflammation in rat arthritis and MMP-13 expression.

OBJECTIVE: Rheumatoid arthritis (RA) is one systemic auto-immune disorder featured as chronic synovitis and can destruct joint cartilage. Fibroblast-like synoviocyte (FLS) secretes various factors affecting chondrocyte matrix and degradation. This study thus investigated the effect of interleukin-17A (IL-17A) on FLS and osteoclast.

MATERIALS AND METHODS: Type II collagen-induced arthritis (CIA) rats were assigned to CIA model, CIA + IgG1 isotype, and CIA + Anti-Rat IL-17A groups. Tissue volume and arthritis index (AI) evaluated arthritis condition. ELISA and flow cytometry measured IL-17A content and Th17 cell percentage in joint cavity fluid. Matrix metallopeptidase 13 (MMP-13) and collagen type II alpha 1 (COL2A1) expression in synovial tissues were compared. FLS-osteoclast co-culture system was treated with IL-17A + IgG1 Isotype or CIA + Anti-Rat IL-17A. MMP-13 and COL2A1 expression were compared.

RESULTS: CIA model rats had significantly higher IL-17A and Th17 cell ratio in joint cavity fluid. Injection of Anti-Rat IL-17A decreased AI and tissue volume in model rats, decreased MMP-13 while increased COL2A1 expression in synovial or cartilage tissues. IL-17A treatment remarkably up-regulated MMP-13 mRNA or protein expression in chondrocytes. Anti-IL-17A weakened effects of IL-17A on FLS or chondrocytes.

CONCLUSIONS: IL-17A inhibits COL2A1 mRNA and protein expression of chondrocyte in the co-culture system via inducing MMP-13 expression in FLS, thus enhancing collagen degradation and playing a role in RA-related cartilage injury.