IL17A and rheumatoid arthritis: At present, the mechanism of joint destruction in rheumatoid arthritis is not clear, but research has found that synovial mesenchymal cells driven by transcription factor c-Fos/AP-1 (6), fibroblast like synovial cells (7), osteoclasts, cytokines including TNF, IL1, IL17, rheumatoid factors, anti CCP antibodies and other autoantibodies all play a role in the occurrence of joint destruction in rheumatoid arthritis (8).