内质网应激介导EHEC O157志贺毒素诱导的肠上皮细胞自噬型死亡机制研究

EHEC O157:H7 infection is a serious threat to public health and national biosafety. Shiga toxin (Stx2) produced by this bacteria, which can damage the intestinal epithelial cells, is the main reason to cause hemorrhagic colitis and serious complications, but the pathogenic mechanisms did not reveal clear. In previous researches, our team observed that Stx2 can induce autophagic cell death (APCD) in intestinal epithelial cells, while inhibition of endoplasmic reticulum stress (ER stress) could decreased APCD,which may be mediated through Akt/mTOR signaling pathway. Through up or down regulating the expression of ER stress and autophagy in cell and animal models with Stx2 treatment,the present reserch tries to detect APCD and its signaling pathway with Western blot/electron microscopy/confocal laser microscope in intestinal epithelial cells, and analyze the relationship among the APCD/apoptosis/necrosis, to explore the model of "Stx2, ER stress and APCD". We intend to clarify the mechanism that ER stress regulates autophagic cell death induced by Stx2 in intestinal epithelial cells, and provide a theoretical basis for an effective treatment to EHEC O157:H7 infection.

EHEC O157:H7感染严重威胁公共卫生和国家生物安全，其产生的志贺毒素（Stx2）损伤宿主肠粘膜上皮细胞，是导致出血性结肠炎等严重并发症甚至死亡的主要原因，其致病机制未揭示清楚。课题组前期观察到Stx2能诱导肠上皮细胞自噬型死亡（APCD），同时抑制内质网应激可减少自噬和细胞死亡，可能通过Akt/mTOR信号通路介导。本项目拟在体内外，通过上调或下调内质网应激和自噬，利用Western Blot、电镜、共聚焦等观察Stx2引起的肠上皮APCD及相关信号通路蛋白表达变化，并分析APCD与凋亡、坏死的关系，探讨"Stx2、内质网应激以及APCD"的作用模式，以期阐明内质网应激在Stx2毒素诱导肠上皮细胞自噬细胞死亡的机制,为EHEC O157:H7感染导致的疾病寻找新的防治手段提供理论依据。

肠出血性大肠杆菌(enterohaemorragic Escherichia coli，EHEC) O157:H7（本文简称EHEC O157）作为一种新发传染病病原，自1982年被确认为致病菌以来，其引发的感染性疾病在世界各地包括我国均发生了暴发流行。感染该菌可使人患腹泻、出血性结肠炎（Hemorrhagic colitis, HC），并引发溶血性尿毒综合征（Hemolytic uremic syndrome, HUS）及血栓性血小板减少性紫癜（Thrombotic thromobocytopenic purpura, TTP）等严重并发症，严重者可导致死亡，致死率达5～10%。在体内外，通过上调或下调内质网应激和自噬，利用Western Blot、电镜、激光共聚焦显微镜等技术观察EHEC O157 Stx2引起的肠上皮APCD及相关信号通路蛋白表达变化，并分析APCD与凋亡、坏死的关系，探讨“Stx2、ER Stress以及APCD”的作用模式，项目组发表SCI论文1篇，影响因子11分。通过本项目研究阐明了内质网应激在EHEC O157 Stx2毒素诱导的肠上皮细胞自噬细胞死亡的机制，为EHEC O157感染导致的疾病寻找新的防治手段提供理论依据。