SIRT1/SIRT3信号通路在大骨节病软骨损伤机制中的作用研究

Kashin-Beck Disease (KBD) and osteoarthritis (OA), which are characterized by degenerative articular cartilage degeneration, manifest as degradation of cartilage matrix , chondrocyte death and destruction of joint integrity. But KBD is a endemic, degenerative osteoarthropathy. Its etiology and pathogenesis have not been clear by now. The disease mainly affects the children before the closure of tubular metaphysis. OA is a chronic degenerative disease of the active joints, which is closely related to age. The older, the risk of OA is greater. Do children suffer from KBD because of the therapeutic factors inhibiting the function of the "longevity gene" that leading to the onset of OA earlier? The role of silent information regulator 2 (Sir2) enzymes 1 (SIRT1,a longevity gene) has been preliminary revealed in the mechanism of OA cartilage degeneration，and SIRT3 is closely related to mitochondrial damage. Whether SIRT1/SIRT3 also regulates the occurrence and development of KBD, it has not been reported up to now. This project is planned to explore the issue by case, cell and animal experiments.

大骨节病(Kashin-Beck Disease,KBD)与骨关节炎(osteoarthritis,OA)均以关节软骨退行性变为特点，表现为软骨基质降解、软骨细胞死亡和关节完整性破坏。但KBD是一种地方性、变形性骨关节病，至今病因和发病机制尚不明确，该病主要侵犯管状骨干骺闭合前的儿童；而OA是一种与年龄密切相关的活动关节慢性退行性病变，年龄越大OA患病风险越大。儿童罹患KBD是否由于治病因子抑制了“长寿基因”的功能导致了老年OA早发呢？长寿基因--沉默信息调节因子相关酶SIRT1在OA软骨退变机制中的作用已得到初步的揭示，而SIRT3与线粒体损伤密切相关，SIRT1/SIRT3是否也调控了KBD的发生与发展，未见相关报道。本项目拟通过病例、细胞和动物实验进行研究探讨。

大骨节病是一种地方性、变形性骨关节疾病，易感人群是儿童和少年，以关节软骨退行性变为特点，表现为软骨基质降解、软骨细胞死亡和关节完整性破坏，至今病因和发病机制尚不明确。为解答是否由于大骨节病致病因子抑制了沉默信息调节因子（长寿基因）SIRT1/SIRT3的功能导致了关节软骨退行性变早发，致使儿童罹患大骨节病，本项目通过人群、细胞和动物实验来探讨SIRT1和SIRT3在细胞自噬、凋亡和基质代谢相关信号转导通路中的作用，探究SIRT1和SIRT3在KBD中的可能机制。人群实验结果显示KBD患者外周血SIRT1和SIRT3 mRNA表达降低，与KBD病情严重程度及年龄关系不明显；KBD患者软骨细胞SIRT1mRNA和蛋白表达水平低；Wnt-3a/β-catenin信号通路相关因子mRNA水平降低、蛋白表达水平未见差异；MMP-13 mRNA表达升高，MMP-9 mRNA表达下降。T-2毒素诱导的类大骨节病动物模型出现关节软骨细胞萎缩、变性、坏死以及关节软骨细胞外基质降解病理改变。大鼠关节软骨组织中SIRT1、SIRT3蛋白表达下调，自噬（Beclin-1、LC3B、P62、LC3II、LC31）、凋亡（Bax、Bcl-2、Caspase-3）和细胞外基质代谢（MMP-9、MMp-13、II型胶原）关键基因及PI3K/AKT、NF-κB、HIF-1α/AMPK信号通路相关基因mRNA及蛋白表达水平均发生改变，其中PI3K/AKT、NF-κB经典信号通路激活，共同促进了软骨细胞凋亡和细胞外基质降解，HIF-1α/AMPK信号通路被抑制，软骨细胞自噬水平下降。细胞实验表明HT-2毒素可导致软骨细胞衰老水平、凋亡水平、VEGF、MMP-13等炎症因子分泌水平升高，可致SIRT1和SIRT3蛋白表达水平降低，II型胶原分泌水平下降，上调SIRT1可抑制HT-2毒素对PI3K/AKT、Wnt/β-catenin信号通路的激活，降低细胞凋亡水平及细胞外基质的降解。本项目研究结果初步证实了SIRT1和SIRT3在大骨节病发病机制的作用，为研究骨关节疾病治疗靶点提供了一定的参考。