Inhibition of Matrix Metalloproteinase-3 and -13 Synthesis Induced by IL-1β in Chondrocytes from Mice Lacking Microsomal Prostaglandin E Synthase-1

Abstract

Joint destruction in arthritis is in part due to the induction of matrix metalloproteinase (MMP) expression and their inhibitors, especially MMP-13 and -3, which directly degrade the cartilage matrix. Although IL-1β is considered as the main catabolic factor involved in MMP-13 and -3 expression, the role of PGE2 remains controversial. The goal of this study was to determine the role of PGE2 on MMP synthesis in articular chondrocytes using mice lacking microsomal PGE synthase-1 (mPGES-1), which catalyses the rate-limiting step of PGE2 synthesis. MMP-3 and MMP-13 mRNA and protein expressions were assessed by real-time RT-PCR, immunoblotting, and ELISA in primary cultures of articular chondrocytes from mice with genetic deletion of mPGES-1. IL-1β–induced PGE2 synthesis was dramatically reduced in mPGES-1−/− and mPGES-1+/− compared with mPGES-1+/+ chondrocytes. A total of 10 ng/ml IL-1β increased MMP-3 and MMP-13 mRNA, protein expression, and release in mPGES-1+/+ chondrocytes in a time-dependent manner. IL-1β–induced MMP-3 and MMP-13 mRNA expression, protein expression, and release decreased in mPGES-1−/− and mPGES-1+/− chondrocytes compared with mPGES-1+/+ chondrocytes from 8 up to 24 h. Otherwise, MMP inhibition was partially reversed by addition of 10 ng/ml PGE2 in mPGES-1−/− chondrocytes. Finally, in mPGES-1−/− chondrocytes treated by forskolin, MMP-3 protein expression was significantly decreased compared with wild-type, suggesting that PGE2 regulates MMP-3 expression via a signaling pathway dependent on cAMP. These results demonstrate that PGE2 plays a key role in the induction of MMP-3 and MMP-13 in an inflammatory context. Therefore, mPGES-1 could be considered as a critical target to counteract cartilage degradation in arthritis.