miRNA-140通过TGF-β/BMP通路调控软骨细胞自噬在骨关节炎发病机制中的作用研究

Osteoarthritis (OA) is characterized by degeneration of articular cartilage, its pathogenesis is still unclear, and there is currently no effective therapeutic approaches. MiRNA-140, with high cartilage-specificity, exhibits a protective role in articular cartilage, and TGF-β/BMP signalling pathway also plays an important role in regulating cartilage homeostasis. We had found in preliminary study that intra-articular injection of miRNA-140 could obviously prevent rat cartilage degeneration, and miRNA-140 could rescue the OA-like change through regulating TGF-β/BMP pathway in human chondrocyte, but the specific molecular mechanism is unclear. Emerging studies of tumour growth and neural degeneration reported that TGF-β/BMP pathway could regulate cell autophagy, which is plays an important role in cell growth, proliferation and apoptosis. However, few studies focused on the role of autophagy in articular chondrocyte, and conflicting results had been reported. In this study, based on our preliminary experimental results, the effect of miRNA-140, TGF-β/BMP pathway and autophagy on the articular cartilage degeneration was investigated in vitro, in vivo and under different environmental conditions, and further explore the role of miRNA-140 in the pathogenesis of OA through TGF-β/BMP pathway regulating chondrocyte autophagy and illuminate the specific molecular mechanism. New theoretical basis is expected to provide for seeking new therapeutic targets of OA.

骨关节炎（OA）是以关节软骨退变为特征的常见疾病，其发病机制及有效治疗手段尚不明确。miRNA-140具有高度软骨特异性，对软骨起保护作用，TGF-β/BMP通路也对软骨稳态起重要调控作用，我们预实验发现关节腔内注射miRNA-140可明显延缓大鼠关节软骨退变，同时证实miRNA-140可通过调控TGF-β/BMP通路逆转人软骨细胞OA样改变，但具体机制不清楚。文献报道在肿瘤生长及神经退变研究中发现TGF-β/BMP通路可调节细胞自噬，而自噬本身在细胞生长、增殖及凋亡过程中起重要作用，目前软骨细胞中自噬相关研究甚少且结论相互矛盾。本研究拟在前期预实验上，从体外、动物体内及不同环境条件下研究miRNA-140、TGF-β/BMP通路及自噬对软骨退变的作用，探索miRNA-140通过TGF-β/BMP通路调控软骨细胞自噬在OA发病机制中的作用及分子机制，以期为寻找OA新的治疗靶点提供理论基础。

骨关节炎（OA）是以关节软骨退变为特征的常见疾病，其发病机制尚不明确且缺乏有效治疗手段。软骨细胞作为关节软骨中的唯一细胞类型，对软骨基质稳态起决定作用。微小RNA-140-5p（miR-140）具有软骨特异性，是软骨细胞代谢的重要调控因子，而TGF-β/BMP通路是软骨细胞生物学行为的重要调控机制，课题组预实验发现miR-140可通过调控TGF-β/BMP通路改善人软骨细胞OA样改变，但相关机制尚无报道。细胞自噬在细胞生物学行为及命运调控中起关键作用，既往在肿瘤生长研究中发现TGF-β/BMP通路可调控细胞自噬，但软骨细胞自噬相关研究甚少。因此提出假说：miR-140可通过TGF-β/BMP通路调控软骨细胞自噬延缓OA发生发展。本项目以膝关节为对象，通过以下研究内容对该假说进行了充分验证：（1）明确了miR-140在人正常及OA软骨细胞及关节液中的表达随OA程度加重逐渐降低，上调miR-140可促进软骨细胞合成代谢；（2）成功构建了大鼠OA模型，从体内证实了关节腔注射miR-140可延缓关节软骨退变；（3）从体外证实了上调miR-140可通过激活TGF-β通路、抑制BMP通路而促进OA软骨细胞合成代谢；（4）从体外明确了软骨细胞自噬水平随OA程度加重逐渐降低，激活自噬或抑制mTOR通路可促进软骨细胞合成代谢；（5）从体外明确了TGF-β通路激活可上调软骨细胞自噬，BMP通路激活作用相反，同时阐明了其中具体分子机制并在大鼠OA模型中验证；（6）在体内、体外验证了上调miR-140可增强软骨细胞自噬，而TGF-β/BMP通路在该过程中起重要作用。本项目系统阐明了miR-140通过TGF-β/BMP通路调控软骨细胞自噬在OA发病机制中的作用及分子机制，不仅丰富了OA发病机制理论，还为OA治疗策略和靶点研究提供了思路。