Effects of Interleukin 1(IL1)-Induced Matrix Breakdown on Chondrocyte Morphology in Bovine Nasal Cartilage Explants

The objective of this study was to investigate the influence of matrix loss on regulating chondrocyte phenotype, and the synthesis and activation of collagenolytic enzymes. IL1 was used to enhance matrix breakdown in bovine nasal cartilage explants. Change in matrix composition and its effects on chondrocyte morphology were investigated using histochemical techniques. In bovine nasal explants, chondrocytes responded to IL1 to manifest 2 distinct patterns of cell shape exhibiting either pyknotic or enlarged nuclei. Enzyme activity analysis suggested a positive correlation between collagenolytic activity and the occurrence of proteoglycan loss and cell morphology changes. These data suggest that loss of non-collagenous proteins such as proteoglycans may lead to changes in cell shape but this may not be sufficient on its own to create the threshold stimulus for chondrocytes to commit themselves to produce active collagenolytic enzymes.