Host-cell mitochondrial alterations play a central role in EPEC pathogenesis

摘要 引起腹泻的胃肠道病原体肠病原性大肠杆菌(EPEC)是 发展中国家五岁以下儿童的严重发病率和死亡率。确实有 在我们对EPEC如何导致腹泻的理解中存在关键差距。细菌使用类似注射器的III型 分泌系统将关键的毒力“效应物”直接输送到宿主肠道上皮细胞。在 在感染的最初阶段，EPEC提供促进宿主细胞生存的蛋白质。在后来的感染中， 然而，分泌更多的细胞毒性蛋白会导致宿主细胞死亡。在这篇文章中提出的研究 应用重点是感染后不同时间分泌的两个EPEC效应分子， 这对线粒体和宿主细胞的生存有着截然不同的影响。我们假设 效应蛋白对宿主线粒体稳定性和功能的协调和交叉作用 对EPEC的定植和毒力至关重要。这一假设将在三个目标中得到检验，我们将在 将：(1)从机械上确定两个EPEC效应器对宿主线粒体结构的影响；(2) 感染肠上皮细胞线粒体功能的效应依赖性变化特征 建立EPEC分泌的毒力效应物对线粒体的影响 利用兔体内感染模型进行体内功能研究。拟议的研究将确定 EPEC毒力中的关键毒力因子和宿主线粒体扰动。在未来， 我们期待着我们的研究为宿主细胞靶向分子的开发和作为辅助分子的使用提供信息。 对EPEC和相关细菌引起的腹泻的标准治疗方法。

ABSTRACT The gastrointestinal pathogen enteropathogenic E. coli (EPEC) causes diarrhea and is responsible for significant morbidity and mortality in children under five years of age in developing countries. There are key gaps in our understanding of how EPEC causes diarrhea. The bacteria use a syringe-like type III secretion system to deliver key virulence “effectors” directly into host intestinal epithelial cells. In the initial phase of infection, EPEC delivers proteins that promote host cell survival. Later in infection, however, secretion of more cytotoxic proteins results in host cell death. The studies proposed in this application focus on two EPEC effector molecules that are secreted at discrete times post-infection, and that have contrasting impacts on mitochondria, and on host cell survival. We hypothesize that the orchestrated and intersecting actions of effector proteins on host mitochondrial stability and function are critical for EPEC colonization and virulence. This hypothesis will be tested in three Aims where we will: (1) Mechanistically define the impact of two EPEC effectors on host mitochondrial structure, (2) Characterize effector-dependent alterations in mitochondrial function in infected intestinal epithelial cells in vitro, and (3) Establish the impact of EPEC secreted virulence effectors on mitochondrial function in vivo using a rabbit model of infection. The proposed studies will establish the precise role of key secreted virulence factors, and of host mitochondrial perturbations, in EPEC virulence. In the future, we anticipate our studies to inform the development and use of host cell-targeted molecules as adjuncts to standard therapies for treating the diarrhea caused by EPEC and related bacteria.