SIRT1/Pink1/Parkin通路介导的线粒体自噬在磨损微粒诱导人工关节无菌性松动中的作用及机制研究

Aseptic loosening is the most important cause of revision after arthroplasty, which is significantly reduced the life-span of prosthesis and is difficult to detect and treat. Sufficient energy supplied by mitochondrial plays a vital role in bone homeostasis and mitophagy, a kind of selected autophagy, is the major way to recycle and renew the impaired or aged mitochondria. Our previous study revealed that autophagy stimulated by wear particles contributed to the increased apoptosis of osteoblast, impaired production of interferon-beta in osteocytes and activation of osteoblast. Our pre-experiment discovered that mitophagy significantly increased in patients with aseptic loosening and particle-induced osteolysis animal model. The expression of Pink1 and Parkin were stimulated while the expression of SIRT1 was inhibited in osteoblast treated by wear particles. Also, Pink1 had a close correlation with mitophagy in osteoblast. Therefore, we speculate that wear particles are able to stimulate mitophagy via SIRT1/Pink1/Parkin pathway in osteoblast, which results in energy deficiency and cell apoptosis, and cause osteolysis and aseptic loosening. We also aim to develop novel therapeutic strategies based on this theory to inhibit osteolysis by regulating the level of mitophagy.

无菌性松动是关节置换术后翻修的最常见原因，严重影响了关节假体的使用寿命，难以监测和治疗。线粒体功能及线粒体自噬在维持骨组织微环境稳态中起着重要作用。我们的前期研究发现，磨损微粒可通过影响自噬水平造成成骨细胞凋亡增加，进而促进骨溶解的发生。我们的预实验结果显示无菌性松动患者及模型动物骨组织内存在异常活跃的线粒体自噬并伴有线粒体功能损伤，细胞实验显示磨损微粒可显著改变成骨细胞中SIRT1、Pink1以及Parkin的表达水平，且Pink1表达与线粒体自噬密切相关。推测在无菌性松动发病过程中，磨损微粒可通过SIRT1/Pink1/Parkin通路过度激活线粒体自噬，进一步影响成骨细胞能量供应以及细胞功能，从而导致局部骨溶解以及无菌性松动的发生。本项目聚焦于无菌性松动的病理机制研究，针对成骨细胞中异常的线粒体自噬水平进行干预，以期阐明线粒体自噬在无菌性松动中的作用机理，探索防治无菌性松动的新方法。

无菌性松动是关节置换术后翻修的最常见原因，严重影响了关节假体的使用寿命，难以监测和治疗。线粒体功能及线粒体自噬在维持骨组织微环境稳态中起着重要作用，是目前骨组织代谢研究的热点。我们的前期研究发现，磨损微粒可通过影响自噬水平造成成骨细胞凋亡增加，进而促进骨溶解的发生。本项目基于前期研究基础，进一步明确了线粒体自噬在磨损微粒诱导成骨细胞凋亡中的作用。在无菌性松动患者骨组织以及模型小鼠颅骨组织中发现存在异常活跃的线粒体自噬并伴有成骨细胞水平的降低。模型小鼠颅骨组织单细胞测序结果也提示线粒体数量及功能改变在磨损微粒诱导骨溶解中发挥重要作用，细胞凋亡、自噬异常、免疫炎症反应为重要的细胞生物学过程。进一步细胞实验发现，磨损微粒可显著影响成骨细胞线粒体功能，线粒体碎片化水平及线粒体自噬水平显著增加，细胞凋亡增加。使用线粒体自噬抑制剂可显著改善磨损微粒对成骨细胞的损伤。动物实验明确了线粒体自噬抑制剂可改善磨损微粒诱导的骨溶解。进一步探索信号通路发现SIRT1/Pink1/Parkin通路参与磨损微粒刺激的成骨细胞线粒体自噬过程。本项目在体内和体外两个水平探索局部磨损微粒通过线粒体自噬对成骨细胞的作用，探讨线粒体自噬在磨损微粒诱导的人工关节无菌性松动的发病过程中的作用及具体机制。本项目在无菌性松动机制探索中提出了线粒体自噬这一新概念，可进一步探索通过关节假体涂层、关节腔给药等方式进行临床转化，为无菌性松动防治探索了新方向。