Bacillus-containing vacuole-mediated interactions of Bacillus anthracis with macrophages

含芽孢杆菌液泡介导的炭疽芽孢杆菌与巨噬细胞的相互作用

• 批准号: 8829616
• 负责人: Steven R. Blanke
• 金额: $ 19.83万
• 依托单位: UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-01 至 2017-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8829616
• 关键词: Address; Agreement; Alveolar; Alveolar Macrophages; Anthrax disease; Bacillus (bacterium); Bacillus anthracis; Bacillus anthracis spore; Back; Binding; Biology; Blood Circulation; Breathing; Cell surface; Cells; Cellular Structures; Cessation of life; Chimeric Proteins; Cytosol; Data; Deposition; Development; Disease; Environment; Exocytosis; Francisella tularensis; Germination; Goals; Grant; Human; Immune; In Vitro; Infection; Integration Host Factors; Intracellular Membranes; Knock-out; Knowledge; Literature; Lung; Mediating; Membrane; Membrane Fusion; Modeling; Molecular; Pathway interactions; Phagocytes; Process; Proteins; Proteome; Recruitment Activity; Reporting; Reproduction spores; Research; Salmonella enterica; Shigella flexneri; Testing; Time; Translating; Transmission Electron Microscopy; Vacuole; Vesicle; Work; base; extracellular; fluorescence imaging; in vivo; killings; knock-down; macrophage; pathogen; prevent; public health relevance; synaptotagmin VII; uptake

 DESCRIPTION (provided by applicant): During inhalational anthrax, considerable evidence indicates that alveolar macrophages (mφs) contribute to the development of disseminated infection and disease by transporting dormant B. anthracis (Ba) spores, previously inhaled into the alveolar spaces of the lungs, to the bloodstream. Although the initial steps of spore uptake into mφs have been extensively studied, a major gap in knowledge, which is the focus of this exploratory R21 application, is the mechanism by which intracellular Ba escape infected mφs as a requisite step prior to extracellular dissemination. Here, we propose studies that challenge an existing model that predicts, analogous to several different intracellular pathogens, mφ death must precede Ba release to the external environment. Instead, our preliminary data indicate that subsequent to phagocytic uptake of dormant spores into Bacillus-containing vacuoles (BCVs), a substantial fraction of intracellular Ba escape in the absence of mφ killing. Because we find no evidence that Ba depart BCVs into the cytosol of infected mφs, we propose that these intracellular vacuoles represent specialized niches that are important for Ba escape. In support of this idea, infection with Ba enhances transport of lysosomal contents to the cell surface, and, induces the time-dependent enrichment of BCVs with the membrane vesicle fusion protein, synaptotagmin-7, consistent with an exocytic process. Based on these preliminary data, we will evaluate the overall hypothesis that non-lytic escape of intracellular Ba from infected mφs requires remodeling of BCVs from degradative to exocytic compartments. We will identify changes in BCV-associated proteins during the course of Ba infection, and, characterize their functional importance for the maturation of BCVs into compartments associated with egress of intracellular Ba back to the extracellular environment. These studies will provide the first detailed characterization of the intracellular niche occupied by Ba spores, and contribute to our understanding of the fundamental biology underlying inhalational anthrax.

 描述（由申请人提供）：在吸入性炭疽期间，大量证据表明，肺泡巨噬细胞（mφs）通过运输先前吸入肺泡空间的休眠炭疽芽孢杆菌（Ba）孢子，促进播散性感染和疾病的发展，尽管孢子摄入 mφ 的初始步骤已被广泛研究，但知识上存在重大差距，这是本文的重点。这一探索性的 R21 应用是细胞内 Ba 逃逸受感染的 mφ 的机制，作为细胞外传播之前的必要步骤。在这里，我们提出的研究挑战了现有模型，该模型预测，类似于几种不同的细胞内病原体，mφ 死亡必须先于 Ba 释放。相反，我们的初步数据表明，在将休眠孢子吞噬到含有芽孢杆菌的液泡（BCV）中后，很大一部分发生了变化。由于我们没有发现 Ba 离开 BCV 进入受感染 mφ 细胞质的证据，因此我们认为这些细胞内液泡代表了对 Ba 逃逸非常重要的特殊生态位，以支持这一观点。与 Ba 一起增强溶酶体内容物向细胞表面的转运，并诱导 BCV 与膜囊泡融合蛋白突触结合蛋白-7 的时间依赖性富集，与基于这些初步数据，我们将评估以下总体假设：细胞内 Ba 从受感染的 mφ 中非裂解性逃逸需要将 BCV 从降解区室重塑为胞吐区室。我们将鉴定 Ba 过程中 BCV 相关蛋白的变化。感染，并表征它们对于 BCV 成熟到与细胞内 Ba 回到细胞外环境相关的区室的功能重要性。这些研究将提供 Ba 占据的细胞内生态位的第一个详细特征。孢子，并有助于我们了解吸入性炭疽的基础生物学。