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Characterization of vacuole escape in Shigella infection

志贺氏菌感染中液泡逃逸的特征

基本信息

批准号：
9976031
负责人：
HERVE F AGAISSE
金额：
$ 23.75万
依托单位：
UNIVERSITY OF VIRGINIA
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-02-01 至 2022-01-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9976031
关键词：
Actins Acyltransferase Africa Agreement Animal Model Asia Bacteria Biochemical Bioinformatics Cell Line Cell membrane Cell physiology Cells Cessation of life Chemicals Colon Confocal Microscopy Country Cysteine Cytoskeleton Cytosol Defect Disease Distal Dose Epithelial Cells Foundations Genetic HT29 Cells Hemorrhagic colitis Human Human Volunteers Income Individual Infant Infection Inflammation Intestinal Mucosa Intestines Invaded Latin America Mass Spectrum Analysis Measures Mediating Membrane Modeling Modification Molecular Monomeric GTP-Binding Proteins Mucous Membrane Mutation Needles Oral Oryctolagus cuniculus Outcome Pathogenesis Pathology Pathway interactions Prevention Preventive Intervention Process Proteins Research Proposals Resolution Role Route Sanitation Shigella Infections Shigella flexneri Site Supporting Cell System Testing Therapeutic Intervention Time Travel Type III Secretion System Pathway Vacuole base cell motility cellular imaging design diarrheal disease enteric pathogen genetic approach high risk human model human pathogen imaging approach in vivo inhibitor/antagonist innovation insight low income country microbial mutant neonatal infection nonhuman primate pathogen polymerization recruit uptake

项目摘要

The intracellular pathogen Shigella flexneri is the causative agent of bacillary dysentery in humans. In low- income countries, poor sanitation is responsible for approximately 270 million cases of shigellosis annually, with at least 250,000 of these resulting in death. In high-income countries, shigellosis is typically associated with travel to high-risk regions (Latin America, Asia and Africa). The disease is characterized by severe bloody diarrhea and dramatic destruction of the colonic mucosa. S. flexneri is transmitted via the fecal-oral route and is extremely contagious, with a rate of attack above 90% with an infectious dose as low as 100-1000 bacteria per individual, as determined in human volunteer studies. S. flexneri is an intracellular pathogen that invades epithelial cells in the human colon. The bacteria trigger their own entry by injecting bacterial effector proteins through their type 3 secretion system (T3SS), leading to bacterial uptake into primary cellular vacuoles. The pathogen promptly escapes from primary vacuoles to gain access to the cytosolic compartment. In the cytosol, bacteria recruit components of the actin cytoskeleton and actin polymerization at the bacterial pole propel the pathogen throughout the cell. As motile bacteria reach cell-cell contacts, they form membrane protrusions that project into adjacent cells. The resolution of the formed protrusions leads to formation of double-membrane vacuoles (DMVs) in adjacent cells, from which the pathogens escape, thereby achieving cell-to-cell spread. The importance of this dissemination process in S. flexneri pathogenesis has been initially established through studies conducted in non-human primates or in human volunteers and recently demonstrated by our group in an infant rabbit model of bacillary dysentery. Although actin-based motility is now fairly well understood, the mechanisms supporting cell-to-cell spread are unclear. Our group has previously shown the importance of the T3SS in bacterial dissemination. Moreover, we have recently identified the T3SS effector protein IcsB as a critical determinant of DMV escape during cell-to-cell spread. Here we propose to explore how IcsB contribute to DMV escape in epithelial cells (Aim1) and how IcsB-mediated DMV escape contributes to pathogenesis in vivo (Aim2).

细胞内病原体福氏志贺氏菌是人类细菌性痢疾的病原体。在低在收入国家，卫生条件差每年造成约 2.7 亿例志贺氏菌病，其中至少有 250,000 人因此死亡。在高收入国家，志贺氏菌病通常与前往高风险地区（拉丁美洲、亚洲和非洲）。该病的特点是严重流血腹泻和结肠粘膜的严重破坏。福氏链球菌通过粪口途径传播传染性极强，发病率在90%以上，感染剂量低至100-1000个细菌根据人类志愿者研究确定的每个人的情况。弗氏沙门氏菌是一种细胞内病原体，可侵入人类结肠中的上皮细胞。细菌通过注入细菌效应蛋白来触发自身进入通过其 3 型分泌系统 (T3SS)，导致细菌摄取到初级细胞液泡中。这病原体迅速从初级液泡中逸出，进入胞质室。在细胞质中，细菌招募肌动蛋白细胞骨架的成分，并在细菌极聚合肌动蛋白，推动病原体遍布细胞。当运动细菌到达细胞与细胞接触时，它们会形成膜突起，投影到相邻的单元格中。所形成的突起的分解导致双膜的形成邻近细胞中的液泡（DMV），病原体从中逃逸，从而实现细胞间传播。这这种传播过程在福氏链球菌发病机制中的重要性已初步确定在非人类灵长类动物或人类志愿者中进行的研究，最近由我们的小组在细菌性痢疾幼兔模型。尽管基于肌动蛋白的运动现在已经得到很好的理解，支持细胞间传播的机制尚不清楚。我们小组之前已经表明了 T3SS 细菌传播。此外，我们最近发现 T3SS 效应蛋白 IcsB 是一种 DMV 在细胞间传播过程中逃逸的关键决定因素。在这里我们建议探索 IcsB 如何做出贡献上皮细胞中 DMV 逃逸的影响 (Aim1) 以及 IcsB 介导的 DMV 逃逸如何促进以下疾病的发病机制体内（目标2）。