Interleukin-1 beta affects cyclooxygenase-2 expression and cartilage metabolism in mandibular condyle

Extracellular matrix degradation in mandibular condylar cartilage is mediated by various cytokines in the temporomandibular joint (TMJ). Interleukin-1 beta (IL-1β) is detected in joint structures with pathologic status, and participates in catabolic action in the extracellular matrix. The purpose of this study was to investigate the effects of IL-1β on cyclooxygenase-2 (COX-2) expression and cartilage metabolism using cultured chondrocytes from mandibular condyle. Articular chondrocytes from the porcine mandibular condylar cartilage around the surface were cultured and treated with 0-10 ng/ml IL-1β or 0-1000 ng/ml prostaglandin (PGE2) for 0-24 h. The mRNA levels of COX-2, MMP-1, -3, and -13 were evaluated by real-time PCR analysis. The protein levels of PGE2 and MMPs were examined by ELISA and Western blot analysis, respectively. The expression levels of COX-2 and PGE2 were enhanced by exogenous IL-1β in chondrocytes. The mRNA levels of MMP-1, -3, and -13 were up-regulated by PGE2 treatment dose-dependently. It is shown that the expression of COX-2/PGE2 was enhanced by IL-1β in articular chondrocytes from mandibular condyle, and that MMP-1, -3, and -13 were induced by PGE2, suggesting that IL-1β-induced COX-2/PGE2 play a crucial role in catabolic processes of mandibular condylar cartilage under inflammatory conditions.