Degradation of Cartilage Collagens Type II, IX, X and XI by Enzymes Derived from Human Articular Chondrocytes

Abstract

Conditioned culture medium derived from Interleukin-I α-activated human articular chondrocytes contained both collagen- and proteoglycan-degrading activities.Preparations of soluble type I collagen and the cartilage collagens type II, IX, X and XI were all degraded when incubated with the conditioned culture medium at 35°C.Fractionation of the enzymic activities using column chromatography with Ultragel AcA 34 and Heparin-Sepharose allowed the separation and identification of neutral proteinase, collagenolytic and proteoglycan-degrading activities.Eluant fractions which contained type I collagenase activity effectively degraded collagen type II, but these fractions did not correspond precisely with those which degraded collagen types IX, X and XI.These observations indicate that chondrocytes have the potential to produce a conventional interstitial type II collagenase together with other enzymes having some specificity for the minor collagens.Thus IL-1-activated chondrocytes produce a range of collagenolytic and proteoglycan-degrading enzymes which can process most of the structural components of the cartilage matrix.