PKR在磨损颗粒激活巨噬细胞NLRs信号通路引起人工关节无菌性松动中的作用机制

As the most effective treatment for end-stage osteoarthropathy, arthroplasty is widely performed. Over 1,000,000 joint prostheses are implanted every year over the world. Inevitable aseptic loosening of joint prostheses severely limits the life span of artifical joints. However, there's no effective method to prevent or to treat the aseptic loosening. The applicant has conducted in-depth researches in Germany and in China under the support of NSFC funds. We found that wear particles from prostheses could classically activate macrophages via TLRs (Toll-like receptors) to produce pro-inflammatory cytokines, which activate osteoclasts. Osteoclasts are involved in peri-prosthetic osteolysis, which results in the aseptic joint loosening. However, RNA interference targeting TLRs signaling pathway of macrophages couldn't totally inhibit the secretion of pro-inflammatory cytokines. Our recent researches revealed that NLRs (NOD-like receptors) is the other important signal pathway in this process besides TLRs. Latest literature reported that PKR (Protein Kinase R) is an important target in the regulation of macrophage NLRs. Up to date, no literature has reported the effect of PKR on aseptic joint loosening. On the basis of previous researches, this project will explore the mechanism of PKR in macrophage NLR pathway activation induced by wear particles in aseptic joint loosening. We will provide experimental proofs to clarify the molecular mechanism of aseptic joint loosening, and provide a new horizon in its prevention and treatment.

人工关节置换术是治疗终末期骨关节疾病最有效的方法，全球每年有超过100万套的假体被植入，但术后不可避免的假体无菌性松动严重制约了人工关节的使用寿命，目前却无有效的方法来防治它。本人在德国留学期间及回国后国家自然基金资助下的研究发现：来源于假体的磨损颗粒通过TLRs经典激活巨噬细胞所产生的前炎症因子可进一步激活破骨细胞引起假体旁骨溶解，这是导致人工关节无菌性松动的主要原因，但靶向抑制TLRs仅能部分阻断该过程。我们近期发现NLRs是除TLRs外参与这一过程的另一重要信号通路，最近有研究提出PKR（Protein Kinase R）是调控巨噬细胞NLRs的关键靶点，但其在人工关节无菌性松动中的作用尚无文献报道。本研究将在以往的基础上，通过体内、外实验探讨PKR在磨损颗粒激活巨噬细胞NLRs中的作用，为明确人工关节无菌性松动的分子机制提供直接实验依据，为防治人工关节无菌性松动开辟新的思路。

人工关节无菌性松动是引起人工关节置换术后假体失效的主要原因之一，如何有效防治该并发症是骨科领域研究的热点问题。在本研究中，我们旨在阐明PKR/NLRs通路在巨噬细胞诱导的体内和体外无菌性关节松动中的作用。我们在32名进行初次全髋关节置换术（THA）或翻修手术的患者中观察到NOD2、NLRP3、TNFα和IL-1b的高度表达。磨损颗粒可激活巨噬细胞中NOD2，PKR, NLRP3，NF-κB通路，MAPK通路并引起促炎细胞因子TNF-α、IL-1b等的表达上调。另外，抑制PKR上游的NOD2可进一步上调NF-κB通路，MAPK通路和TNF-α的表达。敲除NOD2基因增强了钛颗粒诱导的小鼠颅骨模型中的骨溶解。本项目的研究结果显示，NOD2、PKR和NLPR3均参与了磨损颗粒激活巨噬细胞引起人工关节无菌性松动的过程，并明确了NOD2在钛颗粒诱导的骨溶解中起负向调节作用。

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