2010 年 8 巻 1 号 p. 9-18
Recent studies demonstrated that hydroxyl radical (OH⋅;) and various extracellular matrix degrading enzymes coexisted in osteoarthritic TMJ (OA-TMJ), however exact roles of these molecular species are not fully understood. We tried to elucidate whether OH⋅; could modify pro-form of matrix metalloproteinase-9 (MMP-9) to acquire collagenolytic activity. OH⋅; was generated in vitro by Fenton reaction where the reaction was originated by mixing hydrogen peroxide and FeSO4-7H2O. When exposed to OH⋅;, the intensity of the pro-form of MMP-9 (92kDa) was decreased but intermediately- (83kDa) and fully-activated (67kDa) MMP-9 were increased in their intensities. The activated MMP-9 could cleave type IV collagen. It was thus demonstrated that MMP-9 was partially- or fully- activated in vitro by OH⋅; without losing its collagenolytic function. These results suggest that among various pathways of MMP activation, free radical-prone pathway is really existed, and this could be feasible in the OA-TMJ.