整合素调控的自噬/凋亡在幽门螺杆菌感染免疫逃逸中的作用机制研究

Helicobacter pylori, as one of the pathogens which are seriously threatened human health, could escape the host immune response and cause persistent H. pylori infection. Autophagy and apoptosis play important roles in immune escape. Integrin has been proved as an impormant receptor for many kinds of pathogens and virus. It brings out an urgent need to elucidate the roles of integrin on regulating autophagy and apoptosis after H. pylori infection. In the present project, RNA interference, function block, immunofluorescence and transmission electron microscope (TEM) techniques are applied to study the effects of integrin to gastric epithelial cell autophagy after H. pylori infection. We hope to elucidate the effects of integrin-ILK-FAK signal pathways under the process of autophagy and apoptosis. And with the the dynamic effects of autophagy and apoptosis to the survival of intracellular H. pylori, we also hope to clarify the molecular mechanism of H. pylori immune escape. The results of this study not only can ascertain the mechanism of integrin in the immune escape of H. pylori, but also can offer important scientific data which are significant to look for potential prevention method and treatment targets to block the H. pylori chronic infection.

幽门螺杆菌是危害人类健康的重要病原体之一，它可逃逸宿主免疫系统从而导致感染持续存在。自噬和凋亡在其免疫逃逸过程中起着关键作用。整合素（integrin）已被证实是多种病原菌、病毒进入宿主细胞的重要受体，而integrin在幽门螺杆菌感染时如何调控胃上皮细胞自噬和凋亡过程却鲜有报道。本研究拟以体外细胞试验和临床样本分析相结合的手段，通过RNA干扰、功能封阻、免疫荧光和透射电镜等技术，研究幽门螺杆菌感染时integrin对胃上皮细胞自噬活性的调控作用；探讨integrin-ILK-FAK信号通路对自噬和凋亡过程的影响；并结合自噬和凋亡对胞内幽门螺杆菌存活的动力学影响，揭示幽门螺杆菌免疫逃逸的分子机理。研究结果不仅能够明确integrin在幽门螺杆菌免疫逃逸时发挥的作用机制，还能够为寻找新的防治幽门螺杆菌慢性感染手段提供理论依据。

作为胃粘膜病变的重要致病因子，幽门螺杆菌可逃逸宿主免疫系统，导致感染的持续存在。为了阐明幽门螺杆菌感染时integrin及介导的信号通路在调控胃上皮细胞自噬和凋亡中的作用，揭示integrin在幽门螺杆菌感染发生免疫逃逸时发挥的作用机制，开展了本研究工作。本研究通过临床组织样本分析、小鼠幽门螺杆菌感染模型和细胞实验共同发现：①幽门螺杆菌可通过降低胃上皮细胞中β1-integrin蛋白水平，诱导自噬发生；②β1-integrin通过integrin-linked kinase（ILK）调控幽门螺杆菌诱导的细胞自噬，其机制可能与FAK/Paxillin/F-actin通路有关；③幽门螺杆菌可通过降低胃上皮细胞中ILK蛋白水平，扰动自噬，其机制可能与ILK调控的Rac1/RhoA/F-actin信号通路有关；④幽门螺杆菌能通过ILK信号通路诱导胃上皮细胞凋亡，并通过Caspase-3及PARP的表达增强自噬引起凋亡；⑤ILK影响幽门螺杆菌毒力因子CagA细胞内的降解。通过上述研究，我们阐明了幽门螺杆菌可通过β1-integrin调控ILK信号通路影响胃上皮细胞的自噬和凋亡，并且β1-integrin和ILK可作为幽门螺杆菌慢性感染的防治靶点用于后续研究。