Proteoglycans from experimental osteoarthritic cartilage: degradation by neutral metalloproteases.

This study deals with the analysis of the structure of cartilage proteoglycans in experimental osteoarthritis. We have demonstrated that chondrocytes in osteoarthritic cartilage synthesize proteoglycans which have the same functional characteristics as those of normal cartilage. Osteoarthritic cartilage contains metallodependent proteoglycan degrading enzymes, in both active and latent forms. These enzymes degrade both synthesized and endogenous proteoglycan macromolecules, as indicated by the reduced hydrodynamic size found in both proteoglycan populations in osteoarthritic cartilage treated with APMA. Our results also suggest the possibility that proteolytic degradation can occur at both the hyaluronate-binding region and in the chondroitin-sulfate-rich region of the proteoglycan core protein.