XBP1在调节OA关节软骨损伤中的作用与机制研究

Damage and degeneration of articular cartilage are the most direct causes of osteoarthritis (OA).Our previous study (81171697) showed that the OA of PGRN-/- mice exhibited accelerated degeneration and injury of articular cartilage compared with the OA of wild type (WT). The articular cartilage damage will induce ER stress and activate UPR, and the activation of UPR is dependent on PGRN. However, it remains unknown that how to regulate OA occurrence with the UPR important molecule XBP1 and IRE1/XBP1 core signal pathway, its function and mechanism during the injury of OA articular cartilage are also unknown. In this study, we constructed OA mice model with XBP1 conditional knockout (cKO) mice and XBP1 transgenetic (Tg) mice. The models, combined with such methods as mouse metatarsal bones induced culture in vitro, immunohistochemistry (IHC) ,Q-PCR and immunoblotting, detected the function of XBP1 during OA articular cartilage injury, clarified the relationship between OA occurrence modulated by XBP1 and PGRN signal pathway, inflammatory factor TNFa and downstream NF-κB signal pathway, revealed the effect and mechanism of XBP1-mediated UPR signal pathway during the injury of OA articular cartilage and OA occurrence. This study lays the foundation for exploring and parsing the new regulatory mechanisms of inflammation.

关节软骨损伤与退变是骨关节炎(OA)出现的最直接原因。我们前期研究发现(81171697)：与正常小鼠OA相比，PGRN-/-敲除小鼠OA表现出关节软骨的加速退变和损伤；在OA发生过程中，关节软骨损伤会诱导ER stress并激活UPR，UPR激活依赖于PGRN，作为UPR重要分子XBP1及核心通路IRE1/XBP1如何参与OA发生及在OA关节软骨损伤中的作用与机制都不清楚。本研究综合运用XBP1条件性敲除(cKO)小鼠和XBP1 转基因(Tg)小鼠等不同类型小鼠构建OA模型，结合体外趾骨组织团块培养、IHC、Q-PCR、免疫印迹等实验方法，检测XBP1在OA关节软骨损伤中的作用与功能；阐明XBP1调节OA发生与PGRN信号通路、炎性因子TNFa及下游NF-κB信号通路的关系；揭示XBP1介导UPR信号通路调控OA关节软骨损伤与OA发生的作用与机制，为探索和解析新的炎症调控机制奠定基础。

研究证明软骨由于其无血管、无神经的特殊性，受到损伤后几乎不具有自我修复的能力，伴随着软骨的损伤和退变，会引起进行性的组织缺失和功能障碍，导致退行性的骨关节病变；同时，由于年龄、劳损、创伤、肥胖、炎症、代谢障碍、遗传等因素引发炎症导致软骨细胞的损伤和退变、软骨细胞代谢的失衡是诱发骨关节炎的首要因素。本研究综合运用Cre小鼠、XBP1条件性敲除小鼠（XBP1 CKO）、ERN1条件性敲除小鼠（ERN1 CKO）和PGRN-/-敲除小鼠及C57 WT等一系列不同品系的小鼠，分别采用DMM和ACLT手术构建小鼠骨关节炎模型。运用构建好的小鼠OA模型，联合重组腺病毒Ad-XBP1s、siXBP1s、PGRN干细胞悬液及PGRN重组蛋白，并结合小鼠体外趾骨组织团块培养、免疫组化、realtime PCR、免疫印迹等实验方法，研究XBP1s和PGRN在小鼠OA关节软骨损伤与修复过程中的作用与机制；明确XBP1s在OA关节软骨损伤中的作用与功能；检测和鉴定炎性因子TNF-α、IL-1β诱导对XBP1转录的调控作用和调控机制；阐明XBP1s调节OA发生与PGRN信号通路、炎性因子TNFa及下游NF-κB信号通路的关系；揭示XBP1s介导UPR信号通路调控OA关节软骨损伤的作用与机制；探讨骨关节炎OA发生过程中是否会诱导产生ER stress并激活UPR；探讨自噬是否参与骨关节炎OA的发生；阐明UPR与自噬在OA中具体的作用与机制。通过本项目研究，我们系统阐明UPR及XBP1s/u在骨关节炎软骨缺损与再生修复中的作用与机制，为探索和解析新的炎症调控机制、揭示许多炎症疾病的发病机制和病理基础提供理论和实验依据，也为OA的预防和治疗研究寻找到重要的靶分子和突破口，也可能为其他自身免疫性疾病、自身炎症性疾病和反应性炎症性疾病的预防和治疗提供重要的借鉴资料。