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

摘要 肠道致病性E.大肠杆菌（EPEC）引起腹泻， 发展中国家5岁以下儿童的发病率和死亡率很高。有 我们对EPEC如何导致腹泻的理解存在重大差距。这种细菌使用一种类似于细菌的III型 分泌系统将关键毒力"效应物"直接递送到宿主肠上皮细胞中。在 在感染的初始阶段，EPEC递送促进宿主细胞存活的蛋白质。在感染后期， 然而，更多细胞毒性蛋白的分泌导致宿主细胞死亡。本报告中提出的研究 应用集中于两种在感染后离散时间分泌的EPEC效应分子， 对线粒体和宿主细胞的存活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的定殖和毒力至关重要。这一假设将在三个目标中得到检验， 将：（1）机械地定义两个EPEC效应子对宿主线粒体结构的影响，（2） 表征受感染肠上皮细胞中线粒体功能的效应子依赖性改变 （3）确定EPEC分泌的毒力效应物对线粒体的影响， 使用兔感染模型在体内起作用。拟议的研究将确定以下方面的确切作用： EPEC毒力中的关键分泌毒力因子以及宿主线粒体扰动。在未来， 我们希望我们的研究能为宿主细胞靶向分子的开发和应用提供信息， 涉及用于治疗由EPEC和相关细菌引起的腹泻的标准疗法。

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.