Gosset Marjolaine, Berenbaum Francis, Levy Arlette, Pigenet Audrey, Thirion Sylvie, Cavadias Simeon, Jacques Claire
Physiology and Physiopathology Laboratory, Paris Universitas-UPMC Paris VI and CNRS (UMR 7079), 75252 Paris, Cedex 5, France.
Biorheology. 2008;45(3-4):301-20.
Knee osteoarthritis (OA) results, at least in part, from overloading and inflammation leading to cartilage degradation. Prostaglandin E2 (PGE2) is one of the main catabolic factors involved in OA in which metalloproteinase (MMP) is crucial for cartilage degradation. Its synthesis is the result of cyclooxygenase (COX) and prostaglandin E synthase (PGES) activities whereas NAD+-dependent 15 hydroxy-prostaglandin dehydrogenase (15-PGDH) is the key enzyme implicated in the catabolism of PGE2. Among the isoforms described, COX-1 and cytosolic PGES are constitutively expressed whereas COX-2 and microsomal PGES type 1 (mPGES-1) are inducible in an inflammatory context. We investigated the regulation of the COX, PGES and 15-PGDH and MMP-2, MMP-9 and MMP-13 genes by mechanical stress applied to cartilage explants. Mouse cartilage explants were subjected to compression (0.5 Hz, 1 MPa) from 2 to 24 h. After determination of the PGE2 release in the media, mRNA and proteins were extracted directly from the cartilage explants and analyzed by real-time RT-PCR and western blot respectively. Mechanical compression of cartilage explants significantly increased PGE2 production in a time dependent manner. This was not due to the synthesis of IL-1, since pretreatment with IL1-Ra did not alter the PGE2 synthesis. Interestingly, COX-2 and mPGES-1 mRNA expression significantly increased after 2 hours, in parallel with protein expression. Moreover, we observed a delayed overexpression of 15-PGDH just before the decline of PGE2 synthesis after 18 hours suggesting that PGE2 synthesis could be altered by the induction of 15-PGDH expression. MAPK are involved in signaling, since specific inhibitors partially inhibited COX-2 and mPGES-1 expressions. Lastly, compression induced MMP-2, -9, -13 mRNA expressions in cartilage. We conclude that dynamic compression induces pro-inflammatroy mediators release and matrix degradating enzymes synthesis. Notably, compression increases mPGES-1 mRNA and protein expression in cartilage explants. Thus, the mechanosensitive mPGES-1 enzyme represents a potential therapeutic target in osteoarthritis.
膝关节骨关节炎（OA）至少部分是由超负荷和炎症导致软骨降解引起的。前列腺素E2（PGE2）是参与OA的主要分解代谢因子之一，其中金属蛋白酶（MMP）对软骨降解至关重要。其合成是环氧化酶（COX）和前列腺素E合酶（PGES）活性的结果，而NAD+依赖性15-羟基前列腺素脱氢酶（15-PGDH）是参与PGE2分解代谢的关键酶。在所描述的同工型中，COX-1和胞质PGES是组成性表达的，而COX-2和微粒体PGES-1（mPGES-1）在炎症环境中是可诱导的。我们研究了对软骨外植体施加机械应力对COX、PGES和15-PGDH以及MMP-2、MMP-9和MMP-13基因的调控。将小鼠软骨外植体在0.5Hz、1MPa下压缩2至24小时。在测定培养基中PGE2的释放后，直接从软骨外植体中提取mRNA和蛋白质，分别通过实时RT-PCR和western blot进行分析。软骨外植体的机械压缩以时间依赖性方式显著增加PGE2的产生。这不是由于IL-1的合成，因为用IL1-Ra预处理不会改变PGE2的合成。有趣的是，COX-2和mPGES-1 mRNA表达在2小时后显著增加，与蛋白质表达平行。此外，我们在18小时后PGE2合成下降之前观察到15-PGDH的延迟过表达，表明PGE2合成可能因15-PGDH表达的诱导而改变。MAPK参与信号传导，因为特异性抑制剂部分抑制了COX-2和mPGES-1的表达。最后，压缩诱导软骨中MMP-2、-9、-13 mRNA表达。我们得出结论，动态压缩诱导促炎介质释放和基质降解酶合成。值得注意的是，压缩增加了软骨外植体中mPGES-1 mRNA和蛋白质表达。因此，机械敏感的mPGES-1酶代表骨关节炎的一个潜在治疗靶点。
