Journal of Oral Tissue Engineering

ORIGINAL ARTICLE
 Generation of Active-form of Matrix Metalloproteinase-9 Induced by Hydroxyl Radical - A Possible In Vitro Model for Oxidative Stress-induced Degradation of Cartilage Matrix in the TMJ -

 Hiroharu KATO1, Eiro KUBOTA1 and Masaichi-Chang-il LEE2
1Department of Oral and Maxillofacial Surgery,
2Division of Pharmacology and ESR Laboratories,
Kanagawa Dental College, Yokosuka, Japan

J Oral Tissue Engin 2010;8(1): 9-18
SYNOPSIS
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.

Key words: hydroxyl radical, MMP-9, MMP-activation, temporomandibular joint