Atg5介导树突状细胞自噬在烟草烟雾暴露下肺部炎症中的作用及机制的研究

Autophagy is involved in the regulation of innate and adaptive immune responses and its mechanism of action is of great importance for the treatment of chronic obstructive pulmonary disease. Atg5 gene plays an important role in the occurrence and development of autophagy, but its function in chronic obstructive pulmonary disease is not yet clear. Using immunofluorescence, we found that the expression of Atg5 in peripheral blood of patients with chronic obstructive pulmonary disease was lower than that of healthy control group. In addition, serum Atg5 levels in patients with chronic obstructive pulmonary disease were lower than those in healthy controls. In the model of emphysematous mice, we found that the expression of MHC I in lung dendritic cells was up-regulated, and the proliferation and differentiation of CD8 + T cells in the lung were more enhanced than those in the air-exposed group. Accordingly, we hypothesize that under tobacco exposure, dendritic cells may decrease the level of autophagy by down-regulating Atg5, increase MHCI expression through lipid internalization, and induce the proliferation and differentiation of CD8 + T cells to form emphysema. In this study, Atg5-specific knockout mice were used at molecular, cellular and global levels to investigate the role of Atg5 in dendritic form during tobacco exposure by flow cytometry, immunofluorescence mediate the role of lung inflammation. This study will provide new ideas and new targets to reveal the pathogenesis and prevention of chronic obstructive pulmonary disease from the new viewpoint of autophagy of dendritic cells.

自噬参与调控固有免疫和获得性免疫反应，研究其发生机制对COPD治疗具有重要意义。 Atg5基因在自噬发生和发展中发挥重要作用，但其在COPD的功能目前尚不清楚。利用免疫荧光，我们研究发现：COPD患者外周血诱导树突状细胞Atg5表达低于健康对照组；此外，COPD患者血清Atg5的水平低于健康对照组。在小鼠肺气肿模型中，我们发现肺树突状细胞MHCI表达上调，肺部CD8+T细胞增殖分化较空气暴露组增强。据此我们提出假说：烟草暴露下，树突状细胞可能通过下调Atg5，引起自噬水平降低，通过脂质内化引起MHCI表达增加，进而诱导CD8+T细胞增殖与分化，形成肺气肿。本研究拟利用Atg5特异性敲除小鼠，以流式细胞术、免疫荧光等方法，探讨烟草暴露下Atg5在树突状细胞自噬及介导肺部炎症的作用。本研究将从树突状细胞自噬这个新视点为揭示慢性阻塞性肺疾病发生机制及防治提供新思路和新靶点。

烟草烟雾暴露是COPD （chronic obstructive pulmonary disease) 炎症最重要的危险因素。固有免疫与获得性免疫的相互作用是COPD的重要特征，其中中性粒细胞与树突状细胞在COPD发生发展中扮演重要的角色。此外，树突状细胞自噬在COPD中的作用尚不清楚，而中性粒细胞如何调控树突状细胞自噬及具体机制需要进一步探索。据此，本项目观察烟草烟雾刺激中性粒细胞释放的外泌体通过树突状细胞的内化，促进树突状细胞自噬基因LC3B的表达，及NF-kβ水平升高，减少树突状细胞的凋亡，诱导CD4+T细胞向TH17细胞分化。在中性粒细胞存在的情况下，使用自噬抑制剂3-MA，可以部分树突状细胞诱导CD4+T细胞向TH17细胞分化的能力。我们同时证实了来源于中性粒细胞的外泌体可以通过树突状细胞传递给淋巴细胞。最后，我们通过鼻内注射证实中性粒细胞外泌体可以引起小鼠肺泡间隔破坏，肺泡腔扩大等类似于COPD的肺部改变。而注射中性粒细胞外泌体的小鼠肺组织中性粒细胞和TH17比例增加。本项目的完成为COPD的发病机制及防治提供新的思路和治疗靶点。