Prostaglandin Signaling in Wear Debris-induced Osteolysis

描述（由申请人提供）：这是一项资助申请的竞争性更新，该申请在初始资助期间定义了RANKL在全关节置换术周围发生的骨质溶解中的重要性。目前在美国每年有超过400，000例关节成形术用于治疗这种疾病。由于高达20%的关节成形术由于无菌性松动而需要翻修手术，因此关节炎治疗的这种并发症构成了发病率的主要来源，并且代表了数十亿美元的医疗保健成本。在上一个资助期间，我们的工作将筋膜间滑膜成纤维细胞定义为RANKL的主要来源。初步数据表明，RANKL表达依赖于Ti颗粒对考克斯-2和PGE 2产生的刺激。此外，我们的研究结果表明，EP 4受体参与滑膜成纤维细胞中RANKL的诱导。目的1定义了颗粒碎片刺激滑膜成纤维细胞中的考克斯-2并启动导致RANKL表达的细胞内信号的信号传导机制。我们的假设是转录因子NFicB启动滑膜成纤维细胞对颗粒的反应，并且是考克斯-2诱导所必需的。目的2评估缺乏各种EP受体的小鼠滑膜成纤维细胞对颗粒的体外反应，并检查这些细胞在与破骨细胞前体共培养中刺激破骨细胞生成的能力。我们预期EP 4受体将是Ti处理的滑膜成纤维细胞诱导RANKL和破骨细胞形成所必需的。最后，目的3使用缺乏EP受体信号传导的小鼠颅骨骨丢失的体内模型，明确阐述RANKL诱导、破骨细胞形成、基因表达和骨质溶解相关信号。滑膜成纤维细胞的作用将通过成纤维细胞中EP 4受体的条件性缺失来证实。因此，通过一系列高度集成的体外和体内实验，竞争性更新推进了最初资助期的发现。使用转基因模型和现有技术方法将表征SF中NF κ B活化、考克斯-2和PGES 1表达、PGE 2分泌、EP 4受体结合和RANKL表达的顺序事件，作为骨质溶解的关键事件。

DESCRIPTION (provided by applicant): This is a competitive renewal of a grant proposal that during the initial funding period defined the importance of RANKL in the osteolysis that occurs around total joint replacements. There are currently more than 400,000 arthroplasties performed annually in the U.S. to treat this condition. Since up to 20% of arthroplasties require revision surgery due to aseptic loosening, this complication of arthritic treatment constitutes a major source of the morbidity, and represents billions of dollars in health care costs. During the last funding period, our work defined the interfascial membrane synovial fibroblast as a major source of RANKL. Preliminary data show that RANKL expression is dependent upon the stimulation of COX-2 and PGE2 production by Ti particles. Moreover, our findings suggest that the EP4 receptor is involved in the induction of RANKL in synovial fibroblasts. Aim 1 defines the signaling mechanisms through which particulate debris stimulate COX-2 in synovial fibroblasts and initiates intracellular signals leading to the expression of RANKL. Our hypothesis is that the transcription factor NFicB initiates the synovial fibroblast response to particles and is necessary for COX-2 induction. Aim 2 assesses in vitro responses to particles in synovial fibroblast from mice lacking the various EP receptors and examines the ability of these cells to stimulate osteoclastogenesis in co-cultures with osteoclast precursors. We anticipate that the EP4 receptor will be required for RANKL induction and osteoclast formation by Ti treated synovial fibroblasts. Finally, Aim 3 uses an in vivo model of calvarial bone loss in mice lacking EP receptor signaling to definitively address signals involved in RANKL induction, osteoclast formation, gene expression, and osteolysis. The role of the synovial fibroblast will be confirmed by conditional deletion of the EP4 receptor in fibroblasts. Thus through a series of highly integrated in vitro and in vivo experiments, the competitive renewal advances the findings of the initial funding period. The use of transgenic models and state of the art methods will characterize the sequential events of NFicB activation, COX-2 and PGES1 expression, PGE2 secretion, EP4 receptor binding, and RANKL expression in SF as a critical event in osteolysis.