Cyclooxygenase inhibitors augment the production of pro-matrix metalloproteinase 9 (progelatinase B) in rabbit articular chondrocytes.

Matrix metalloproteinase 9 (MMP-9/gelatinase B) has recently been proposed to participate in the destruction of articular cartilage. Here, we report that interleukin 1 (IL-1) enhances the production of the precursor of MMP-9 in rabbit articular chondrocytes in primary culture, and this IL-1-mediated production of proMMP-9 is greatly augmented by cyclooxygenase inhibitors such as diclofenac and indomethacin, whereas the constitutive production of proMMP-2 (progelatinase A) is not modulated by IL-1 and/or cyclooxygenase inhibitors. Exogenous prostaglandin (PG) E1 and PGE2 suppress the proMMP-9 production in a dose-dependent manner. Similar results are also obtained with cultured rabbit synoviocytes. These results provide the first evidence that PGE down-regulates the production of proMMP-9 in chondrocytes and synoviocytes. Thus, cyclooxygenase inhibitors probably exert undesirable catabolic actions on the maintenance of articular cartilage under inflammatory conditions.