Degradative enzyme systems in osteoarthritic cartilage.

In osteoarthritis, despite increased matrix synthesis, there is a reduction of both major matrix components, proteoglycan and collagen. This study suggests that this is the result of enhanced degradative activity intrinsic to the cartilage. Because osteoarthritis is a focal disease, histologic controls were used to measure the severity in different areas of the cartilage and in different specimens. Neutral proteoglycanase and collagenase were both described in human cartilage, and their levels matched the severity of the disease as did acid phosphatase, a marker of lysosomal enzymes. Articular cartilage collagenase has an inhibitor in the cartilage and has negligible activity in normal cartilage. This was found not to be a lysosomal enzyme. A model of osteoarthritis was studied and found to have the same biochemical pattern as human disease. Using this method, inhibitors of degradative enzymes were used as a treatment. The chelator of metallic cations EDTA was found to have a significant effect on reduction of degradative enzyme activity and altered the arthritic process.