Role of hypoxia and interleukin-1β in gene expressions of matrix metalloproteinases in temporomandibular joint disc cells

The aim of this study was to test the hypothesis that hypoxia and interleukin-1 (IL-1)β played a substantial role in gene expressions of matrix metalloproteinases (MMPs) in temporomandibular joint (TMJ) disc cells. The TMJ disc cells were isolated from rabbit TMJ, and cultured in Dulbecco’s modified Eagle’s medium (DMEM). The experiment was performed for 24 h in hypoxic (2% O2) and IL-1β stimulated conditions. To examine the effect of hypoxia and IL-1β on gene expression of MMPs and tissue inhibitors of metalloproteinase (TIMPs), we performed reverse transcription–polymerase chain reaction (RT–PCR) and real-time RT-RCR. The results showed that the combination of hypoxia and IL-1β caused a significant increase of MMP-1, MMP-3, MMP-9 and MMP-13 mRNA (P < 0.05). Hypoxia caused a significant increase of MMP-2 mRNA (P < 0.05). The combination of hypoxia and IL-1β caused a significant decrease of TIMP-3 compared to hypoxia (P < 0.05). These findings suggest that hypoxia and IL-1β may contribute to the degradation or remodelling of the extracellular matrix (ECM) of the disc and may have a role in the pathogenesis of TMJ disorders.