Characterization of vacuole escape in Shigella infection

志贺氏菌感染中液泡逃逸的特征

• 批准号: 10088399
• 负责人: HERVE F AGAISSE
• 金额: $ 19.71万
• 依托单位: UNIVERSITY OF VIRGINIA
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-02-01 至 2023-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10088399
• 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; 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; infant infection; inhibitor/antagonist; innovation; insight; low income country; microbial; mutant; nonhuman primate; pathogen; polymerization; preventive intervention; recruit; uptake

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菌是人类细菌性痢疾的病原体。在低- 在低收入国家，卫生条件差每年造成约2.7亿例志贺氏菌病， 其中至少有25万起导致死亡在高收入国家，志贺氏菌病通常与 前往高风险地区（拉丁美洲、亚洲和非洲）的旅行。这种病的特点是严重的出血 腹泻和结肠粘膜的严重破坏。S.福氏杆菌通过粪-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 在人类志愿者研究中确定。S.弗氏菌是一种细胞内病原体， 人类结肠的上皮细胞。细菌通过注射细菌效应蛋白来触发它们自己的进入 通过它们的3型分泌系统（T3 SS），导致细菌摄取到初级细胞空泡中。的 病原体迅速地从初级液泡逃逸以进入胞质区室。在细胞质中， 细菌募集肌动蛋白细胞骨架的组分，并且肌动蛋白聚合在细菌极处推动细胞骨架的形成。 病原体遍布整个细胞。当运动细菌达到细胞与细胞接触时，它们形成膜突起， 投射到相邻的细胞中。形成的突起的分解导致双膜的形成 在邻近细胞中的空泡（DMV），病原体从中逃逸，从而实现细胞到细胞的传播。的 这一传播过程的重要性在S。弗氏病发病机制已初步确立，通过 在非人类灵长类动物或人类志愿者中进行的研究， 一种细菌性痢疾幼兔模型。尽管基于肌动蛋白的运动性现在已经得到了相当好的理解，但 支持细胞间扩散的机制尚不清楚。我们的团队以前已经证明了 细菌播散中的T3 SS。此外，我们最近鉴定了T3 SS效应蛋白IcsB作为一种免疫调节因子。 在细胞间传播期间DMV逃逸的关键决定因素。在这里，我们建议探讨ICSB如何贡献 DMV逃逸上皮细胞（Aim 1）以及IcsB介导的DMV逃逸如何导致 体内（Aim 2）。