EGFR介导幽门螺杆菌空泡毒素诱导胃上皮细胞自噬型死亡的机制研究

Vacuolating cytotoxin (VacA) as a major virulence factor of Helicobacter pylori (H. pylori), can induce excessive or persistent autophagy, which leads to autophagic cell death (APCD) in gastric epithelial cells. This APCD plays crucial roles in the occurrence of chronic atrophic gastritis and gastric ulcer, but the specific mechanism is not clear. Previous studies and our results showed that H. pylori infection could inhibit the expression of EGFR in gastric epithelial cells; VacA toxin inhibited EGFR phosphorylation and Akt/P70S6K phosphorylation, respectively. These results suggested that APCD induced by VacA could be regulated through inhibiting PI3K/Akt/mTOR signaling pathway in gastric epithelial cells. Through up or down regulating the expression of EGFR and autophagy in cell and animal models with VacA treatment,the present reserch tries to detect APCD and its signaling pathway with Western blot/electron microscopy/confocal laser microscope in gastric epithelial cells, to explore the model of "H. pylori VacA, EGFR and APCD". We intend to clarify the mechanism that EGFR regulates autophagic cell death induced by H. pylori VacA in gastric epithelial cells, and provide a theoretical basis for an effective treatment to H. pylori persistent infection.

空泡毒素(VacA)作为幽门螺杆菌（Hp）的主要毒力因子，能诱导胃上皮细胞自噬，而过度自噬可导致胃上皮细胞自噬型死亡（APCD），在慢性胃炎、消化性溃疡等病理损伤中发挥重要作用，但其具体机制尚不清楚。文献报道和课题组前期研究显示：Hp感染者胃粘膜组织EGFR表达下调；VacA能够抑制胃上皮细胞EGFR磷酸化，同时Akt和P70S6K磷酸化均降低，提示VacA诱导的胃上皮APCD可能通过抑制PI3K/Akt/mTOR信号通路介导。本项目拟在VacA所致胃上皮死亡模型中，通过腺病毒、siRNA干扰等技术上调或下调EGFR和自噬，利用WB、电镜、激光共聚焦等技术检测VacA引起的胃上皮细胞APCD及其相关信号通路，并在动物模型中加以验证，探讨"VacA、EGFR以及APCD"的作用模式，以期阐明EGFR在VacA诱导的胃上皮细胞自噬死亡的机制,为寻找Hp感染所致疾病的有效治疗手段提供理论依据。