Effect of interleukin-1 beta on the production of cathepsin B by rabbit articular chondrocytes.

Rabbit articular chondrocytes in monolayer culture were stimulated with human recombinant interleukin-1 beta. Under the influence of the cytokine the intracellular pool of the cysteine endopeptidase cathepsin B was increased by a 2-4-fold factor, while enzyme secretion was not stimulated at a significant level. Under the same conditions, the secretion of collagenase, measured as an internal control, was stimulated about 6-fold. The effects of interleukin-1 beta were compared to those caused by phenotypic modulation. Chondrocytes modulated by serial subcultures in monolayer secreted more cathepsin B, but less collagenase than differentiated cells (cultured within collagen gels). Thus, interleukin-1 beta and phenotypic modulation affected differently two endopeptidases which are relevant in the pathogenesis of osteoarthritis.