Rheumatoid arthritis (RA) is an inflammatory disease characterized by destruction of synovial joints, 1 abnormal immune responses 2 and inflammatory manifestations, 3 which seriously affects human joints. 4 Although much progress has been made in the development of effective drugs for RA, the disease-associated disability rate is still high. Genetical studies have shown that rheumatoid factors 5 and a variety of inflammatory processes 6 play an important role in the mechanism of RA, albeit the etiology of the disease still not understood.