Cartilage degradation by neutral metalloproteases in experimental collagen-like syndrome

In this study, we sought to determine the role of neutral proteases in cartilage matrix proteoglycan degradation, which occurs during the experimental hydralazine-induced collagen-like syndrome (c-l-s) in rats. The digestion of endogenous proteoglycans by neutral proteases in homogenates of cartilage from rats with c-l-s has been measured and compared with that of normal age-matched controls. Cartilage specimens from the tibial plateau were analysed for DNA and proteoglycan content, and neutral proteoglycan-degrading activity, No significant difference in cartilage DNA concentration was observed among the rats with c-l-s and the controls. Total neutral proteoglycan-degrading metallo-enzyme activity, determined by direct tissue assay, was significantly higher in c-l-s cartilage than that in control cartilage. Serine protease activity on proteoglycans was much lower than that of metalloprotease. The results of this study are consistent with the hypothesis that the neutral metalloproteases of cartilage are involved in the degradation of proteoglycans in c-l-s.