Autoantibodies to type II collagen in rheumatoid arthritis and juvenile idiopathic arthritis: meaning and clinical interest

Type II collagen (CII) is the major protein in articular cartilage. Autoantibodies to native and denatured CII (anti-CII) have been reported in rheumatoid arthritis (RA) and juvenile idiopathic arthritis (JIA). The real meaning of the anti-CII antibodies appearance is still an open question. Anti-CII antibodies may occur more commonly very early in the disease course, suggesting that these autoantibodies could be associated with the pathophysiology of RA and JIA. This finding is supported by the fact that in collagen antibody-induced arthritis (CAIA) mouse model, immunization with anti-CII antibodies directed towards several epitopes on CII in joint cartilage can induce polyarthritis that shares several pathological features with RA. This review focuses on the inflammatory events that may be associated with anti-CII production and also the clinical application of these antibodies in RA and JIA.