ROLE OF INTIMIN IN TISSUE TROPISM AND DAMAGE BY EHEC

说明(改编自应用程序) 肠出血性大肠杆菌(EHEC)是引起腹泻病和 美国的肾功能衰竭。EHEC定植于大肠粘膜，而 肠出血性大肠杆菌感染的肠外表现是由吸收引起的 穿过肠道EHEC产生的志贺样毒素(STX)的上皮。 在附着于结肠上皮期间，细菌破坏宿主细胞。 细胞骨架，并在下面形成高度组织的细胞骨架结构 结合细菌，称为附着和消退(AE)病变。内膜，一种 介导宿主细胞紧密附着的细菌外膜蛋白，是 形成AE损伤和完全毒力所必需的。实验性感染 EHEC表达病原菌EPEC的内膜蛋白 感染不同的肠道部位，提示内膜影响 组织嗜性。我们假设：(1)内膜在 确定定植部位；以及(2)内膜介导 肠上皮细胞的细胞骨架破坏促进了 STX感染到肠外部位。为了刻画内膜的特征， 影响组织趋向性和促进STX易位，以下问题 将解决以下问题： 1.表达EPEC内膜蛋白的EHEC菌株是否受到适当的调控 对照显示了组织取向的改变？EHEC染色体EAE编码 序列将具体替换为EPEC EAE编码序列，并且 这一改变对组织趋向性的影响将被评估。 2.什么结构域的内膜会影响肠道定植部位？这个 EPEC内膜区域负责组织趋向性的差异 我们希望在AIM中发现1将通过分析表达基因的菌株来鉴定 EHEC/EPEC杂交内膜蛋白。 3.产生强健的AE病变的能力是否与粘膜损伤相关 和/或毒素移位？同基因的EHEC菌株在能力上的不同 产生AE损害的特征是粘膜损害和 毒素在肠道上皮细胞间的转运。 通过详细了解内膜蛋白在血管内皮细胞生长中的作用 肠出血性大肠杆菌的发病机制，拟议的实验可能导致治疗 旨在最早的步骤之一防止殖民的战略或 最大限度地减少感染后肠道对毒素的吸收 已经成立了。

DESCRIPTION (adapted from the application) Enterohemorrhagic E. coli (EHEC) is an important cause of diarrheal disease and renal failure in the U.S. EHEC colonizes the mucosa of the large bowel, and the extraintestinal manifestations of EHEC infection result from the absorption across the epithelium of Shiga-like toxin (Stx) produced by intestinal EHEC. During attachment to colonic epithelium, the bacterium disrupts the host cell cytoskeleton and forms a highly organized cytoskeletal structure underneath the bound bacterium, termed an attaching and effacing (AE) lesion. Intimin, a bacterial outer membrane protein that mediates tight host cell attachment, is required for AE lesion formation and full virulence. Experimental infection with EHEC expressing intimin from enteropathogenic E. coli (EPEC), a pathogen that infects a different intestinal site, suggested that intimin influences tissue tropism. We postulate that: (1) intimin plays a central role in determining the site of colonization; and that (2) intimin-mediated cytoskeletal disruption of intestinal epithelial cells facilitates delivery of Stx to extraintestinal sites. To characterize the features of intimin that influence tissue tropism and promote Stx translocation, the following questions will be addressed: 1. Does an EHEC strain that expresses EPEC intimin under appropriate regulatory controls demonstrate altered tissue tropism? The EHEC chromosomal eae coding sequence will be specifically replaced by the EPEC eae coding sequence, and the effect of this alteration on tissue tropism will be assessed. 2. What domain of intimin influences the site of intestinal colonization? The region of EPEC intimin responsible for the differences in tissue tropism that we expect to find in Aim 1 will be identified by analyzing strains that express hybrid EHEC/EPEC intimin proteins. 3. Does the ability to generate robust AE lesions correlate with mucosal damage and/or toxin translocation? Isogenic EHEC strains differing in their ability to generate AE lesions will be characterized for differences in mucosal damage and in translocation of toxin across intestinal epithelium. By developing a detailed understanding of the role of intimin in the pathogenesis of EHEC, the proposed experiments may lead to therapeutic strategies designed to prevent colonization at one of the earliest steps or to minimize the intestinal absorption of toxin after infection has been established.