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 人死亡和 17 人患病，扰乱了商业和政府活动，并引起了广泛的焦虑。炭疽芽孢杆菌的感染形式是孢子，是在应激期间形成的一种休眠且具有抵抗力的结构。沿着吸入途径，炭疽芽孢杆菌孢子被肺泡巨噬细胞吞噬并在那里发芽。有趣的是，炭疽芽孢杆菌不会干扰吞噬体成熟，并且能够在吞噬溶酶体中茁壮成长。经过一段时间的延迟后，新萌发的细胞会产生一种在宿主巨噬细胞中生存所必需的三联毒素。与它们对炭疽芽孢杆菌孢子的脆弱性相反，巨噬细胞可以轻松杀死产生毒素的炭疽芽孢杆菌营养细胞。这些结果是违反直觉的：新萌发的细胞不会早期产生毒素，并且应该比营养细胞更容易受到巨噬细胞的攻击。为了解释这一悖论，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炭疽芽孢杆菌孢子萌发时释放的吡啶二羧酸 (DPA) 复合的高浓度钙离子。当炭疽芽孢杆菌孢子在宿主体内萌发时，Ca-DPA 库将位于巨噬细胞内。哺乳动物细胞中的钙水平受到严格控制，破坏可能导致细胞凋亡。或者，DPA 的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，含有 K+ 而不是 Ca+2 的炭疽芽孢杆菌孢子表现出较低的细胞毒性（图 2）。基于这些结果，我们假设钙和/或 DPA 的释放可以保护发芽的炭疽芽孢杆菌细胞免受巨噬细胞的作用，并且是炭疽毒力的决定因素。为了检验我们的假设，我们将研究两个相关问题：(1) 炭疽芽孢杆菌孢子的细胞毒性是否依赖于钙和/或 DPA 浓度；(2) 受感染巨噬细胞中钙和 DPA 的命运如何？