Summary
The effect of exogenous hyaluronate on normal cartilage metabolism and interleukin-1 (il-1)-induced cartilage matrix degradation was investigated in a bovine cartilage explant culture system. Addition of hyaluronate at a concentration of 1.5 mg/ml to cartilage culture explants consistently decreased normal proteoglycan release from the matrix to a value less than that found in control cultures. Addition of 1.5 mg of hyaluronate/ml to il-1 stimulated cartilage culture systems reduced proteoglycan release from the matrix by 83 to 113%. The reduction in control and il-1-stimulated proteoglycan degradation by hyaluronate had a concentration-dependent trend.
Evaluation of alterations in protein (enzyme) release by il-1-stimulated chondrocytes after introduction of hyaluronate was evaluated by use of sodium dodecyl sulfate agar gel electrophoresis of cartilage-conditioned media. The quantity or the molecular weight profile of il-1-induced proteins did not differ after introduction of hyaluronate into the culture system.
Results indicate that introduction of high molecular weight hyaluronate into cartilage culture systems results in a decrease in proteoglycan release from the matrix in control systems, as well as in cultures incubated with il-1. Because il-1-stimulated protein synthesis by chondrocytes remains unchanged after addition of exogenous hyaluronate, the mechanism of inhibition of matrix degradation does not appear to be interference with binding of il-1 to chondrocytes or to be inhibition of the production of neutral metalloproteases, including stromelysin.
