低氧/HIF-α通路在骨细胞参与磨损颗粒诱导假体周围骨溶解中的作用和机制研究

Wear particle-induced aseptic osteolysis is an important cause of prosthetic loosening after arthroplasty. Currently, studies have showed that it is not effective to improve the abnormality of bone quality and microstructure caused by osteolysis only with use of anti-bone absorption or pro-bone formation drugs. Therefore, it is very necessary to explore a new mechanism that can synergistically regulate bone resorption, bone formation and bone microstructure reconstruction under inflammatory conditions. Osteocytes are important effectors that can regulate bone remodeling and bone microstructure reconstruction under inflammatory conditions during the process of osteolysis. Recently, we found that wear particles could significantly inhibit the expression of HIF-1α and HIF-2α in osteocytes, meanwhile the activation of hypoxia/HIF-α pathway could greatly delay the differentiation of osteocytes, inducing them a change in biological behavior that was contrary to wear particle action. Therefore, we speculated that the wear particles may induce the biological behavior changes of osteocytes and periprosthetic osteolysis by inhibiting the expression of hypoxia/HIF-α pathway in osteocytes. In order to verify our speculation, morphology, molecular biology and other means will be applied in vivo and vitro to clarify the specific process and molecular mechanism that wear particles inhibit the expression of hypoxia/HIF-α pathway in osteocytes and induce periprosthetic osteolysis. This study can not only deepen the understanding of periprosthetic osteolysis, but also hope to provide a theoretical basis for hypoxia/HIF-α pathway as a target, prevention and treatment of osteolysis and promote bone repair.

磨损颗粒诱导的无菌性骨溶解是关节置换术后假体松动发生的重要原因。目前，单纯行抗骨吸收、促骨形成治疗并不能有效改善骨溶解引起的骨质量及显微结构异常，因此，仍需探索能从多层面协同调控炎症性骨吸收、骨形成及骨显微结构重塑的新机制。骨细胞是骨溶解过程中调控炎症性骨改建、骨显微结构重建的重要效应细胞。我们新近的研究发现，磨损颗粒能抑制骨细胞HIF-1α、HIF-2α的表达，激活低氧/HIF-α通路能延缓骨细胞的分化，促使其产生与颗粒作用相反的生物学行为改变。因此，推测磨损颗粒可能通过抑制低氧/HIF-α通路的表达，促使骨细胞生物学行为改变，诱导骨溶解。本研究拟借助形态学、分子生物学等手段，通过体内和体外实验，阐明磨损颗粒抑制骨细胞低氧/HIF-α通路表达诱导骨溶解的具体过程及分子机制。这不仅有助于加深对假体周围骨溶解的认识，还有望为以低氧/HIF-α通路为靶点，防治骨溶解、促进骨修复提供理论依据。

磨损颗粒诱导的无菌性骨溶解是关节置换术后假体松动发生的重要原因。目前磨损颗粒调控骨细胞生物学行为诱导骨溶解的具体机制尚不明确，仍需进一步研究。本课题通过动物模型构建、体外细胞培养、免疫组织化学以及分子生物学实验方法探讨了磨损颗粒对骨细胞生物学行为的影响，进一步阐述了低氧模拟化合物去铁敏（DFO）防治磨损颗粒诱导骨溶解的疗效及作用机制。研究结果显示，与正常骨组织相比，假体松动患者骨组织中Cleaved-Caspase-1、Cleaved-IL-1β表达显著升高，骨细胞焦亡显著激活。UHMWPE颗粒诱导小鼠颅盖骨组织中Cleaved-Caspase-1、Cleaved-IL-1β表达显著升高， UHMWPE颗粒干预后的MLO-Y4 Cleaved-Caspase-1、Cleaved-IL-1β表达显著升高，IL-1β含量显著增多。应用caspase-1抑制剂Ac-YVAD-CMK干预后UHMWPE颗粒诱导的骨溶解改善，破骨细胞生成减少。UHMWPE颗粒能显著上调小鼠颅盖骨组织、骨细胞系MLO-Y4 中LC3B的表达，下调P62的表达，应用自噬抑制剂3-MA干预能显著升高骨细胞焦亡标志物Caspase-1、Cleaved-IL-1β的表达。DFO能时间依赖性上调骨细胞MLO-Y4 LC3B的表达，激活骨细胞自噬，同时下调Cleaved-Caspase-1、Cleaved-IL-1β表达，抑制骨细胞焦亡。UHMWPE颗粒能通过诱导骨细胞焦亡方式促进假体周围骨溶解，作为机体的一种自我保护机制，自噬能减轻UHMWPE颗粒诱导的骨细胞焦亡，DFO能通过活化自噬的方式阻抑UHMWPE颗粒诱导的骨细胞焦亡，防治假体周围骨溶解。本项研究成果进一步阐释了磨损颗粒诱导假体周围骨溶解的发生机制，为以骨细胞焦亡、自噬以及低氧模拟化合物为靶点，设计和构建药物，防治骨溶解储备了科学基础。