Hypoxia increases expression of matrix metalloproteinase-3 in temporomandibular joint disc cells

Abstract

Objectives. The aim of this study was to test the hypothesis that hypoxia plays a substantial role in the expression of matrix metalloproteinase-3 (MMP-3) in temporomandibular joint (TMJ) disc cells and may have a role in the pathogenesis of temporomandibular disorders (TMD).Study design. (1) Immunohistochemical study of human TMJ discs: The expressions of MMP-3 and hypoxia inducible factor 1-alpha (HIF-1α) in human TMJ discs were examined by immunohistochemical method using anti-MMP-3 and anti-HIF-1α antibodies. Twelve human TMJ discs (10 samples with internal derangement of the TMJ and 2 control samples) were used. (2) In vitro study of rabbit TMJ disc cell: The TMJ disc cells were isolated from rabbit TMJ and cultured in Dulbecco's modified Eagle's medium. The experiment was performed in hypoxic (2% O2) and IL-1β–stimulated conditions. To examine the effect of hypoxia on gene expression of MMP-3, reverse-transcription polymerase chain reaction (RT-PCR) and real-time RT-PCR were performed. To examine the effect of hypoxia on protein synthesis and activity of MMP-3, immunofluorescent staining, western blot analysis, and casein zymography were performed.Results. (1) The positive expressions of MMP-3 and HIF-1α were observed in the internal derangement of the TMJ, whereas no or weak positive expressions were observed in the control samples. (2) Hypoxia caused a significant increase of gene expression (P < 0.05) and protein synthesis of MMP-3.Conclusions. These findings suggest that hypoxia may contribute to the degradation or remodeling of the extracellular matrix of the TMJ disc and may have a role in the pathogenesis of TMD. Objectives. The aim of this study was to test the hypothesis that hypoxia plays a substantial role in the expression of matrix metalloproteinase-3 (MMP-3) in temporomandibular joint (TMJ) disc cells and may have a role in the pathogenesis of temporomandibular disorders (TMD). Study design. (1) Immunohistochemical study of human TMJ discs: The expressions of MMP-3 and hypoxia inducible factor 1-alpha (HIF-1α) in human TMJ discs were examined by immunohistochemical method using anti-MMP-3 and anti-HIF-1α antibodies. Twelve human TMJ discs (10 samples with internal derangement of the TMJ and 2 control samples) were used. (2) In vitro study of rabbit TMJ disc cell: The TMJ disc cells were isolated from rabbit TMJ and cultured in Dulbecco's modified Eagle's medium. The experiment was performed in hypoxic (2% O2) and IL-1β–stimulated conditions. To examine the effect of hypoxia on gene expression of MMP-3, reverse-transcription polymerase chain reaction (RT-PCR) and real-time RT-PCR were performed. To examine the effect of hypoxia on protein synthesis and activity of MMP-3, immunofluorescent staining, western blot analysis, and casein zymography were performed. Results. (1) The positive expressions of MMP-3 and HIF-1α were observed in the internal derangement of the TMJ, whereas no or weak positive expressions were observed in the control samples. (2) Hypoxia caused a significant increase of gene expression (P < 0.05) and protein synthesis of MMP-3. Conclusions. These findings suggest that hypoxia may contribute to the degradation or remodeling of the extracellular matrix of the TMJ disc and may have a role in the pathogenesis of TMD.