Significance of the levels of carboxy terminal type II procollagen peptide, chondroitin sulfate isomers, tissue inhibitor of metalloproteinases, and metalloproteinases in osteoarthritis joint fluid.

The joint fluid levels of several molecules that reflect the anabolism and catabolism of cartilage matrix and its inflammation were quantitated in patients with primary osteoarthritis (OA) and traumatic arthritis. The carboxy terminal type II procollagen increased in primary OA and traumatic arthritis joint fluid and was thought to be a good marker of the repair response of chondrocytes. We found that the increase of this molecule in the joint correlated well with body mass index in primary OA and the degree of cartilage erosion caused by joint instability in traumatic arthritis. Chondroitin 6-sulfate, an integral part of human aggrecan, was also high in OA and traumatic arthritis joint fluids, and showed a similar distribution with keratan sulfate in each disease group. Stromelysin-1 and tissue inhibitor of metalloproteinases-1 levels in joint fluid were very high in RA, but levels in patients with OA were low. Carboxy terminal type II procollagen appeared most sensitive in the evaluation of risk factors of OA such as obesity and joint instability, compared to other markers tested.