The role of calcium-DPA in the virulence of Bacillus anthracis spores

钙-DPA在炭疽芽孢杆菌孢子毒力中的作用

• 批准号: 8434772
• 负责人: Ernesto V Abel-Santos
• 金额: $ 39.85万
• 依托单位: UNIVERSITY OF NEVADA LAS VEGAS
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-01-15 至 2015-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8434772
• 关键词: Accounting; Alveolar Macrophages; Anthrax Attack; Anthrax disease; Anxiety; Apoptosis; Bacillus anthracis; Bacillus anthracis spore; Bacteria; Biological Assay; Bioterrorism; Breathing; Buffers; Businesses; Calcium; Calcium ion; Cations; Cell physiology; Cells; Complex; Dyes; Ensure; Environment; Exhibits; Fluorescence; Fluorescent Dyes; Genes; Germination; Goals; Government; Human; Image; In Vitro; Label; Laser Scanning Confocal Microscopy; Lead; Mammalian Cell; Measures; Organelles; Pathway interactions; Phagolysosome; Phagosomes; Process; Proteins; Radiolabeled; Reproduction spores; Resistance; Role; Route; Spatial Distribution; Stress; Structure; Testing; Time; Toxin; Virulence; base; cytotoxicity; dipicolinic acid; inhibitor/antagonist; killings; macrophage; nucleoside analog; public health relevance; radiotracer; release of sequestered calcium ion into cytoplasm; sensor

DESCRIPTION (provided by applicant): The anthrax attacks of October 2001 caused five fatalities and 17 illnesses, disrupted business and government activities, and caused widespread anxiety. The infective form of B. anthracis is the spore, a dormant and resistant structure formed during periods of stress. Following the inhalation route, B. anthracis spores are phagocytized by alveolar macrophages where they germinate. Interestingly, B. anthracis does not interfere with phagosome maturation and is able to thrive in the phagolysosome. After a delay, the newly germinated cells produce a tripartite toxin that is necessary for survival in the host macrophage. In contrast to their vulnerability to B. anthracis spores, macrophages kill toxin-producing vegetative B. anthracis cells with ease. These results are counterintuitive: Newly germinated cells do not produce toxins early and should be more vulnerable than vegetative cells to macrophage attack. To account for this paradox, we propose that factors unique to Bacillus anthracis spores can account for the ability of germinated cells to survive the macrophage's phagosome. One distinctive candidate is the large concentrations of calcium ions complexed with dipicolinic acid (DPA) that is released upon B. anthracis spore germination. The Ca-DPA depot will be localized inside macrophages when B. anthracis spores germinate in the host. Calcium levels are strictly controlled in mammalian cells and disruptions can lead to apoptosis. Alternatively, DPA release could buffer the acidification of the phagolysosome. As proof-of principle, we have shown that B. anthracis spores containing K+ instead of Ca+2 exhibit reduced cytotoxicity (Fig. 2). Based on these results, we hypothesize that the release of calcium and/or DPA protects germinated B. anthracis cells from macrophage action and is a determining factor in anthrax virulence. To test our hypothesis, we will look into two related issues: (1) is te cytotoxicity of B. anthracis spores dependent on calcium and/or DPA concentrations and (2) what is the fate of calcium and DPA in infected macrophages?

描述（由申请人提供）：2001年10月的炭疽袭击造成5人死亡，17人患病，扰乱了商业和政府活动，并引起了广泛的焦虑。B的传染形式。炭疽是孢子，是在压力期间形成的休眠和抵抗结构。在吸入途径之后，B.炭疽孢子在其萌发处被肺泡巨噬细胞吞噬。有趣的是，B。炭疽菌不干扰吞噬体成熟，并且能够在吞噬溶酶体中茁壮成长。经过一段时间后，新萌发的细胞产生一种在宿主巨噬细胞中生存所必需的三联毒素。与他们对B的脆弱性形成对比。炭疽孢子，巨噬细胞杀死产生毒素的繁殖体B。炭疽菌细胞。这些结果是违反直觉的：新萌发的细胞不会在早期产生毒素，应该比营养细胞更容易受到巨噬细胞的攻击。为了解释这个矛盾，我们提出炭疽芽孢杆菌孢子特有的因素可以解释萌发细胞在巨噬细胞吞噬体中存活的能力。一种独特的候选物是与吡啶二羧酸（DPA）络合的大浓度的钙离子，其在B上释放。炭疽孢子萌发。当B.炭疽孢子在宿主体内萌发。钙水平在哺乳动物细胞中受到严格控制，破坏可导致细胞凋亡。或者，DPA释放可以缓冲吞噬溶酶体的酸化。作为原理证明，我们已经证明了B.含有K+而不是Ca+2的炭疽孢子表现出降低的细胞毒性（图2）。基于这些结果，我们假设钙和/或DPA的释放保护萌发的B。炭疽细胞的巨噬细胞的作用，是炭疽毒力的决定因素。为了验证我们的假设，我们将研究两个相关的问题：（1）是细胞毒性的B。炭疽孢子依赖于钙和/或DPA浓度和（2）什么是钙和DPA的命运在感染的巨噬细胞？