Role of mitogen-activated protein kinases and NFκB on IL-1β-induced effects on collagen type II, MMP-1 and 13 mRNA expression in normal articular human chondrocytes

Interleukin-1 beta is a pro-inflammatory cytokine that causes anti-anabolic and catabolic effects on articular chondrocytes via four major signaling pathways. In this study, we investigated the role of these pathways for the repression of collagen type II, and induction of MMP-1 and -13 by II-1 beta. Human adult chondrocytes were stimulated with IL-1 beta together with selective inhibitors of the ERK, JNK, p38, and NF kappa B pathways. Inhibitors of ERK and NF kappa B could significantly block the induction of MMP-1 and -13 (p < 0.05) and the repression of collagen type II (p < 0.01). The inhibitor for p38 MAPK was able to block partially MMP-1 and -13 up-regulation (p < 0.01), but did not significantly inhibit collagen type II repression. Our data suggest that ERK and NFkB pathways are particularly important for IL-1 beta regulating collagen type II and MMP-1 and -13 expression and that p38, but not JNK is additionally involved in MMP-1 and -13 induction.