自噬介导肠缺血再灌注肺损伤的作用及机制研究

Intestinal ischemia/reperfusion (II/R) injury not only causes local intestinal injury, but also leads to systemic distal organs damage, especially acute lung injury (ALI). It is very difficult to cure and the mortality rate is high. Until now, the mechanism of lung injury after intestinal ischemia/reperfusion is not fully understood. In recent years, many studies have shown that autophagy is involved in various organs injury of ischemia/reperfusion (I/R) and lung injury of different causes. C-Jun N-terminal kinase (c-Jun N-terminal kinase, JNK)-bcl-2 signaling pathway regulates autophagy, affects cell apoptosis and inflammation, and participates in tissue injury. However, there is no relevant study about the role of autophagy in the II/R-induced lung injury and its intracellular signal transduction mechanism. Our previous studies showed that II/R induced the activation of JNK and increased the expression of autophagy-associated protein LC3-Ⅱand Beclin-1 .What’s more II/R changed the expression of Bcl-2, Bax and inflammatory cytokine IL-1β, TNF-α and so on in the intestinal and lung tissues. We conclude that JNK-Bcl-2-autophagy-apoptotic & inflammatory signaling pathways are involved in II/R intestinal and lung injury. In this study, we investigate the changes of autophagy in lung injury of patients with II/R, explore the possible role of autophagy-mediated II/R lung injury, and reveal the signal transduction mechanism of JNK-Bcl-2-autophagy-apoptotic & inflammatory signaling pathways involved in lung injury induced by II/R from multi-layered research of molecular, cellular, tissue and animal experiments. This study will provide a potential drug target and ideas for the prevention and treatment of II/R-induced lung injury.

肠缺血再灌注（II/R）肺损伤的发病机理尚不完全清楚。近年来研究表明，自噬参与各器官缺血再灌注损伤及不同病因肺损伤，c-Jun氨基末端激酶（JNK)-Bcl2信号转导调控自噬，自噬通过细胞凋亡及炎症反应参与组织损伤。然而有关自噬在II/R肺损伤作用及其信号转导机制，目前未见报道。本课题组前期研究发现，II/R导致肠及肺组织JNK活化、自噬相关蛋白LC3-Ⅱ、Beclin-1表达增高，凋亡相关蛋白Bcl2、Bax，炎性细胞因子IL-1β、TNFα变化。我们由此推论，JNK-Bcl2-自噬-细胞凋亡及炎症信号通路参与II/R肠和肺损伤。本研究从分子、细胞、组织器官及活体动物实验多层面明确自噬在II/R肺损伤的变化规律，探究自噬介导II/R肺损伤的可能作用，揭示JNK-Bcl2-自噬-细胞凋亡及炎症信号通路参与II/R肺损伤的信号转导机制，为防治II/R肺损伤提供新的药物靶点。

肠缺血再灌注（intestinal ischemia / reperfusion，II/R）损伤不仅引起肠道局部损伤，还导致全身远隔器官损害，特别是急性肺损伤（acute lung injury，ALI），发病机理尚不完全清楚。近年来研究表明，自噬（autophagy）参与不同器官缺血再灌注损伤及不同病因所致肺损伤，发挥不同的作用，然而自噬在II/R 肺损伤的变化、作用及其细胞内信号转导机制尚未深入研究。.本研究通过夹闭SD 大鼠肠系膜上动脉建立II/R 肺损伤模型及细胞实验，从以下4各方面探究自噬在II/R 肺损伤的作用及其分子机制：（1）II/R损伤小肠、肺组织内细胞自噬水平的变化；（2）分别特异性干预JNK 活化、观察自噬变化及组织损伤情况，探究II/R-JNK-自噬与凋亡信号通路在II/R后肺损伤的作用及其机制。（3）通过特异性自噬药物RAP、3-MA干预自噬水平，主要观察肠及肺组织细胞凋亡、炎症相关的基因转录及蛋白表达；细胞凋亡、组织损伤及功能变化，明确自噬在II/R 肺损伤的作用。（4）II/R后肺损伤主要发生在肺泡巨噬细胞的细胞自噬与凋亡，通过小肠上皮细胞IEC-6氧糖剥夺损伤与肺泡巨噬细胞NR8383 Transwell共培养，研究JNK-细胞自噬及凋亡的变化。.研究结果表明，II/R导致肺组织JNK活化、自噬相关蛋白LC3-Ⅱ、Beclin-1及促凋亡蛋白Bax表达增高，抗凋亡蛋白Bcl2、Bcl-xL水平相对下降，主要表现肺泡巨噬细胞、肺泡上皮细胞尤其是肺泡巨噬细胞自噬增强、细胞凋亡明显增加，从而加重肺损伤。.本研究从分子、细胞、组织器官及活体动物实验多层面明确自噬在II/R肺损伤的变化规律，以及自噬在II/R肺损伤的可能作用，初步阐明JNK-自噬-细胞凋亡通路参与II/R肺损伤的信号转导机制，为防治II/R肺损伤提供新的药物靶点。