Effect of the interleukin-1β on gelatinolytic activity and cell morphology of human osteoarthritic chondrocytes in culture

We report the effect of recombinant human interleukin-1β (IL-1β) on cell morphology and on the pattern of matrix metalloproteinase (MMP) gelatinolytic activity expressed by quiescent and growing human osteoarthritic chondrocytes. After treatment with IL1β, gelatin zymography revealed a significant increase of 64-62 kDa MMP-2 active forms suggesting an overexpression of its activator membrane type matrix metalloproteinase-1 (MT1-MMP). IL-1β differentially induced or stimulated the chondrocyte expression of other MMP family members (MMP-1, -3, -8, -9 and -13), resulting in extracellular matrix degradation and finally alteration of cell-matrix interactions and cell morphology, as found by culture examination in phase contrast and light microscopy. Differences regarding gelatinolytic activities in chondrocyte response to the exogenous IL-1β were dependent on the culture conditions and the cell location within the osteoarthritic cartilage.