[Cartilage degradation in rheumatoid arthritis]

Rheumatoid arthritis (RA) is a polyarticular joint disease. The inflammatory process is characterized by infiltration of inflammatory cells into the joints, leading to proliferation of synoviocytes and destruction of cartilage and bone. The Matrix metalloproteinases (MMPs) are a family of zinc-dependent proteinases. It had been well recognized that MMP play major roles in the cartilage breakdown in RA and OA. Moreover ADAM-TS-1, -4, -5 have aggrecanase activity, and also involve the cartilage degradation in RA and OA. Of course they contribute the cartilage homeostasis in healthy subjects. Failure to regulate the synthesis, activation and inhibition of the proteinases finally leads to cartilage destruction. Aggrecan and type II collagen are major components in cartilage matrix. Cleavage of aggrecan by aggrecanase and that of collagen by collagenase are critical steps for degradation of articular cartilage in RA. To prevent the cartilage damage, inflammatory synovitis should be suppressed in early stage.