骨髓间充质干细胞通过核心岩藻糖基化修饰调控肺泡上皮细胞自噬活性在肺间质纤维化中的作用机制

Recent studies have shown that insufficient autophagy after injury of alveolar epithelial cells is an important event that leads to increased myofibroblasts and promotes pulmonary fibrosis. Inhibiting the activity of multiple signaling pathways regulated by the modification of core fucosylation (CF) can reverse the autophagy activity of alveolar epithelial cells, thereby inhibiting the progression of pulmonary fibrosis after injury of alveolar epithelial cell. Mesenchymal stem cells (MSCs) are fibroid stem cells with multidirectional differentiation potential, which can effectively repair tissue damage and delay the progression of pulmonary fibrosis. After the colonization of MSCs, they secrete membrane ligands that bind to the target cells, and the membrane ligands secreted by MSCs may be an important mechanism to regulate CF modification of alveolar epithelial cells to reverse their autophagy activity. In the current study, the real-time spatial and temporal distribution characteristics of MSCs in vivo were monitored by optical in vivo imaging technology, and the effect of MSCs on CF modification was observed with laser scanning confocal microscope. On the basis of the above innovative work, alveolar epithelial cell membrane receptors bound to MSCs-derived ligands will be detected by multiple marker quantitative proteomics, protein localization technology, protein-protein clustering and interaction analysis. This study aims to clarify the molecular mechanism of MSCs targeting CF modification to improve the autophagy activity of alveolar epithelial cells in the treatment of pulmonary fibrosis, and to provide a new idea and intervention strategy for the treatment of pulmonary fibrosis.

新近研究发现肺泡上皮细胞自噬不足是其损伤后引起肌成纤维细胞增多、促进肺间质纤维化发生的重要事件。抑制核心盐藻糖基化（CF）修饰调控的多条信号通路活性可逆转肺泡上皮细胞自噬活性，进而抑制肺泡上皮细胞损伤后致肺间质纤维化进程。骨髓间充质干细胞（MSCs) 是一种具有多向分化潜能的成纤维样干细胞，能有效修复组织损伤，减轻肺间质纤维化进程。MSCs定植后会分泌与靶细胞相结合的膜配体，而MSCs分泌的膜配体可能是调控肺泡上皮细胞CF修饰逆转其自噬活性的重要机制。本研究拟通过活体成像技术实时监测MSCs在体内的时空分布特征；激光共聚焦检测MSCs对CF修饰的影响。在上述创新性工作基础上，采用多重标记定量蛋白组学、定位、聚类及蛋白间相互作用分析筛选与干细胞膜配体相结合的肺泡上皮细胞膜受，阐明MSCs以调控CF为靶点改善肺泡上皮细胞自噬活性治疗肺间质纤维化的机制，为治疗肺间质纤维化提供全新的思路。

特发性肺纤维化（IPF）是一种慢性进行性间质性肺部疾病，其主要特征包括肺泡上皮细胞损伤和成纤维细胞活化。IPF的预后差，死亡率高，目前治疗方法有限，因此有必要寻求新的治疗方法。肺泡上皮细胞损伤后多条信号通路的激活可能会导致肺泡上皮细胞自噬不足，这些信号通路的关键受体蛋白均为糖蛋白，而核心岩藻糖基化（Core fucosylation，CF）是重要的蛋白质糖基化修饰。骨髓间充质干细胞（MSC）能有效修复组织损伤，缓解肺纤维化。本项目使用肺泡上皮细胞条件性FUT8敲除鼠、MLE12细胞和小鼠骨髓间充质干细胞，探讨骨髓间充质干细胞、CF修饰与自噬在肺间质纤维化中的相互作用机制。通过组织染色、免疫印迹分析、免疫荧光、自噬流检测等检测技术，初步证明了肺泡上皮细胞自噬在IPF中被抑制，抑制CF修饰缓解了肺泡上皮细胞自噬的抑制和IPF的严重程度。并且，骨髓间充质干细胞通过抑制CF修饰，缓解了肺泡上皮细胞的自噬不足，在一定程度上缓解了IPF。本项目首次将肺间质纤维化与CF修饰联系起来，对于寻找纤维化治疗的新靶点具有重要意义，并且为骨髓间充质干细胞治疗肺间质纤维化提供了新的理论依据。