激素性骨坏死发病率高、致残率高，受累人群以中青年为主，危害极大，但其发病机制尚不清楚。研究证实，骨细胞凋亡是激素性骨坏死的重要病理特征，针对骨细胞凋亡的研究将有助于揭示激素性骨坏死的分子机制。内质网应激（ERS）途径是近年发现的新的细胞凋亡途径，在多种疾病的发病机制中发挥了重要作用，但其在激素性骨坏死中的作用机制尚未阐明。本项目以原代培养成骨细胞和骨坏死动物模型为研究对象，拟开展下述研究：1.ERS途径是否参与了激素诱导的成骨细胞凋亡，其对成骨细胞的生物学功能有何影响；2.ERS诱导的成骨细胞凋亡途径与经典的线粒体和死亡受体凋亡途径有何不同与关联，能否筛查到ERS特异性标志物；3.抑制ERS途径关键靶标CHOP基因是否可以阻止成骨细胞凋亡和骨坏死的发生发展；研究结果将会揭示激素性骨坏死在亚细胞器内质网水平的分子机制，丰富与充实骨坏死的理论，为激素性骨坏死的防治提供新思路和新途径。

Steroid-induced osteonecrosis of the femoral head is a progressive disease that generally affects patients in the third though fifth decades of life; if left untreated, it leads to complete deterioration of the hip joint. A number of different factors have been implicated in the development of osteonecrosis, but although it has been recognised for over 100 years, the biological mechanisms involved remain unclear. Previous studies have confirmed that osteocyte apoptosis is an important pathological features of steroid-induced osteonecrosis of femoral head. Therefore, recent attention has focused on the role of osteocyte apoptosis. Endoplasmic reticulum stress (ERS) pathway is a new apoptosis pathway and has been implicated in the pathogenesis of many diseases, which has led to the proposal of a new therapeutic approach targeting ER stress. But its mechanism of action in steroid-induced osteonecrosis of femoral head has not been elucidated. On the basis of primary osteoblast cells in vitro and rabbit steroid-induced osteonecrosis of the femoral head animal models in vivo, we will undertake the following studies: 1.Whether the ERS pathway is involved in steroid-induced apoptosis of primary osteoblast cells and its effects on the biological function of osteoblasts, 2 What is the difference between the ERS-induced osteoblast apoptosis pathway with classic mitochondrial apoptotic pathway and death receptor apoptotic pathway? What is the ERS-specific markers? 3 Whether inhibiting the expression of CHOP gene by RNA interferance, which is one of the key target of ERS pathway, can prevent apoptosis of osteoblast cells and delay the occurrence and development of rabbit steroid-induced osteonecrosis models? The results of this study will reveal the molecular mechanisms at the subcellular level of steroid-induced osteonecrosis of femoral head and provide new ideas and new ways for prevention and treatment of steroid-induced osteonecrosis.

糖皮质激素的使用是引起非创伤性股骨头坏死的首要原因，会导致髋关节的疼痛与功能受限，最终股骨头塌陷后会导致功能障碍，需要接受髋关节置换。长期使用糖皮质激素治疗的患者中骨坏死的发生率占9-40%。糖皮质激素作用于骨组织会引起成骨细胞、破骨细胞和内皮细胞的凋亡。研究表明糖皮质激素致凋亡效应与细胞种类密切相关，内皮细胞相较其他细胞更容易被糖皮质激素引起凋亡。越来越多的证据表明，内皮细胞的凋亡和功能紊乱被认为是糖皮质激素引起的股骨头坏死病理生理过程的关键因素；糖皮质激素会直接损伤内皮细胞致其凋亡，而内皮细胞的凋亡会激活血栓形成的瀑布效应，进而引起股骨头局部的缺血缺氧和股骨头坏死的发生发展。近年来，内质网应激诱导的细胞凋亡受到越来越多的关注，内质网受到外界刺激后可激活包括PERK，IRE1，ATF6在内的三条经典下游信号通路。当细胞面对过强或过长时间的内质网应激后，细胞会走向凋亡。尽管很多研究指出内质网应激与众多疾病的发生发展密切相关，但是有关内质网应激在激素性股骨头坏死的病理生理过程中的作用机制所致甚少。本项目的研究证明了糖皮质激素可以诱发内皮细胞的内质网应激并继而引起内皮细胞的凋亡，导致了内皮损伤，最终导致了股骨头坏死的发生。其中，内质网应激下游的PERK信号通路在此病理生理发生发展过程中发挥着关键作用；阻断内质网应激PERK信号通路，可有效减少糖皮质激素诱导的内皮细胞凋亡；PERK抑制剂GSK2656157可以有效预防激素引起的骨内微血管内皮细胞凋亡、可以有效预防激素对血管内皮的损伤、可以有效预防激素性股骨头坏死的发生；这表明了内质网应激的PERK信号通路与股骨头坏死发生发展的密切关系，为采取相应措施有效防治激素性股骨头坏死的发生发展奠定了坚实的理论基础。