MSCs上调Del-1抑制破骨细胞分化在治疗类风湿关节炎中的作用机制研究

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by an imbalance of osteoblasts and osteoclasts leading to joint damage. Mesenchymal stem cells (MSCs) can rebalance the excessive immune response and improve the function of osteoblasts while inhibit osteoclasts in RA treatment, but the exact mechanism of osteoclasts inhibition is not clear. Collagen-induced arthritis (CIA) model mice established in our previous experiments showed osteogenic differentiation decreased while osteoclastic differentiation increased. In addition, MSCs treatment can promote the expression of osteogenesis-related gene, and also significantly inhibited osteoclast differentiation. Further in vitro cell co-culture experiments found that MSCs can promote Del-1 protein expression in osteoclasts. Del-1, an extracellular matrix protein, has recently been shown to inhibit osteoclast differentiation. Therefore, we speculate that the up-regulation of Del-1 inhibiting osteoclast differentiation and osteoclast function is an important mechanism of MSCs treatment for RA. In this topic, we will focus on the regulatory mechanism of MSCs up-regulating osteoclasts Del-1 and the key role of Del-1 in inhibiting the osteoclast differentiation of RA treated by MSCs, and provide more theoretical and experimental evidence for the clinical application of MSCs in the treatment of RA.

类风湿关节炎（RA）是以成骨破骨细胞失衡导致关节损伤为病理特征的慢性自身免疫性疾病。间充质干细胞（MSCs）治疗RA能够平衡过度免疫反应并促进成骨抑制破骨，但对破骨细胞的确切抑制机制还不明确。我们前期实验建立的胶原诱导性关节炎（CIA）模型鼠成骨分化下降但破骨分化明显增强。MSCs治疗除了能够促进成骨相关基因表达，还显著抑制破骨细胞分化。进一步的体外细胞共培养实验发现MSCs能够促进破骨细胞中Del-1蛋白表达。Del-1是一种细胞外基质蛋白，最近经研究证实具有抑制破骨细胞分化作用，因此我们推测上调Del-1抑制破骨细胞分化和破骨细胞功能是MSCs治疗RA重要机制。本课题将进一步研究MSCs上调破骨细胞Del-1的调控机制以及Del-1在MSCs治疗RA中抑制破骨细胞分化的关键作用，为临床应用MSCs治疗RA提供更加充分的理论和实验依据。

类风湿关节炎（rheumatoid arthritis，RA）是以关节毁损为特征的慢性炎症性自身免疫性疾病，严重者可至残疾，影响日常生活。MSCs（mesenchymal stem cells，MSCs）治疗RA疗效好，安全性高，但机制尚不明确。本项目中，我们成功构建小鼠CIA模型，并以MSCs治疗CIA模型鼠，实验分为正常小鼠组、CIA模型组和MSCs治疗CIA模型鼠组，结果发现MSCs治疗能改善CIA模型鼠全身和关节局部炎症，并抑制关节骨破坏；同时，本研究发现CIA模型鼠关节局部Del-1表达较正常组下降，而MSCs治疗能提高CIA模型鼠关节局部Del-1水平。随后，我们成功构建RAW264.7诱导向破骨细胞分化体系和MSCs与RAW264.7共培养体系，本研究以不同剂量MSCs干预RAW264.7向破骨细胞分化过程，结果显示MSCs能分泌Del-1，且MSCs能有效抑制RAW264.7向破骨细胞分化。本研究采用不同剂量Del-1干预破骨细胞分化过程，结果显示Del-1能抑制RAW264.7向破骨细胞分化，且抑制作用成剂量依赖关系。进一步研究发现Del-1通过ανβ3抑制破骨细胞分化，因此，本项目结果显示MSCs分泌Del-1通过ανβ3抑制破骨细胞分化进而发挥治疗RA作用。本项目进一步阐明了MSCs治疗RA的机制和理论基础，为MSCs治疗RA的临床推广提供更多理论依据。