Bacillus anthracis Targets Involved in Chemokine-Mediated Antimicrobial Activity

炭疽杆菌靶标参与趋化因子介导的抗菌活性

• 批准号: 8822201
• 负责人: MOLLY A HUGHES
• 金额: $ 39.5万
• 依托单位: UNIVERSITY OF VIRGINIA
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-04-05 至 2016-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8822201
• 关键词: A Mouse; A/J Mouse; ATP-Binding Cassette Transporters; Anthrax disease; Anti-Bacterial Agents; Antibiotics; Antimicrobial Cationic Peptides; Antimicrobial Effect; Bacillus (bacterium); Bacillus anthracis; Bacillus anthracis spore; Bacteria; Bacterial Proteins; C57BL/6 Mouse; CXC Chemokines; CXC chemokine receptor 3; CXCL10 gene; CXCL11 gene; CXCL9 gene; CXCR3 gene; Cell division; Cells; Charge; Chemicals; Co-Immunoprecipitations; Data; Development; Electron Microscopy; Escherichia coli; Exhibits; Foundations; Future; Genes; Germination; Gram-Negative Bacteria; Health; Host Defense; Human; Immune response; Immune system; Immunofluorescence Microscopy; Immunoprecipitation; In Vitro; Infection; Infectious Agent; Integral Membrane Protein; Interferons; Invaded; Lead; Leukocytes; Libraries; Listeria monocytogenes; Lung; LytA enzyme; Mediating; Multi-Drug Resistance; Organism; Outcome; Phenotype; Plasmids; Play; Predisposition; Proteins; Publishing; Recombinants; Recruitment Activity; Reporting; Reproduction spores; Resistance; Role; Site; Site-Directed Mutagenesis; Staging; Testing; Therapeutic; Therapeutic Agents; Work; antimicrobial; base; chemokine; constriction; crosslink; drug resistant microorganism; fighting; genetic approach; in vivo; innovation; insight; killings; macromolecule; microorganism; migration; mouse model; mutant; novel; pathogen; receptor; response; small molecule

DESCRIPTION (provided by applicant): Bacillus anthracis Targets Involved in Chemokine-Mediated Antimicrobial Activity Chemokines are chemotactic cytokines that function in host defense by orchestrating leukocyte migration to sites of infection. However, a number of chemokines have also been found to directly kill a range of pathogenic microorganisms through an as yet undefined mechanism. We previously reported that the interferon-inducible CXC chemokines, CXCL9, CXCL10, and CXCL11, block Bacillus anthracis spore germination, reduce spore viability, and kill vegetative cells, with CXCL10 being the most effective. We also reported that C57BL/6 mice, which are resistant to pulmonary B. anthracis Sterne strain infection, produced significant levels of CXCL9, CXCL10, and CXCL11 in their lungs following spore challenge; whereas, highly susceptible A/J mice did not generate significant levels of these chemokines during pulmonary infection. In vivo neutralization of CXCL9, CXCL9/CXCL10, or CXCL9/CXCL10/CXCL11 rendered C57BL/6 mice susceptible to pulmonary anthrax whereas neutralization of their shared receptor CXCR3, which is the receptor expressed on leukocytes recruited to the site of infection by CXCL9, CXCL10, CXCL11, had no impact on survival. These findings support that CXCL9, CXCL10, and CXCL11 have direct antimicrobial effects against B. anthracis both in vitro and in vivo. To identify the vegetative cell target(s) of CXCL10, we screened a B. anthracis transposon mutant library and found that disruption of ftsX, which encodes the transmembrane protein of a widely conserved prokaryotic ABC transporter, resulted in a CXCL10-resistant phenotype. Deletion of the ftsX gene in B. anthracis (i.e., DftsX) resulted in resistance of vegetative cells to CXCL10, and complementation of ftsX restored CXCL10 susceptibility. In contrast, DftsX spores remained susceptible to CXCL10, suggesting that spores have a different CXCL10 target. To further investigate the role of FtsX, as well as other B. anthracis targets of CXCL10, we propose three Specific Aims: 1) Determine the role of FtsX in susceptibility of vegetative cells to CXCL10; 2) Identify spore target(s) of CXCL10; and 3) Determine the role of spore and vegetative bacterial targets of CXCL10 during in vivo infection. These studies will provide a key foundation for the development of innovative therapeutic strategies for treating infections caused by not only B. anthracis but also a range of pathogenic, potentially multi-drug resistant microorganisms.

描述（由申请人提供）：炭疽芽孢杆菌参与趋化因子介导的抗菌活性趋化因子是通过协调白细胞迁移到感染部位在宿主防御中起作用的趋化细胞因子。然而，一些趋化因子也被发现通过一种尚未确定的机制直接杀死一系列病原微生物。我们之前报道过干扰素诱导的CXC趋化因子CXCL9、CXCL10和CXCL11可以阻断炭疽芽孢杆菌孢子萌发，降低孢子活力，杀死营养细胞，其中CXCL10最有效。我们还报道了C57BL/6小鼠，对肺炭疽杆菌Sterne菌株感染具有抗性，在孢子攻击后在其肺部产生显著水平的CXCL9， CXCL10和CXCL11；而高度易感的A/J小鼠在肺部感染期间没有产生显著水平的这些趋化因子。在体内中和CXCL9、CXCL9/CXCL10或CXCL9/CXCL10/CXCL11使C57BL/6小鼠对肺炭疽易感，而中和它们的共同受体CXCR3 （CXCL9、CXCL10、CXCL11募集到感染部位的白细胞上表达的受体）对存活没有影响。这些结果支持CXCL9、CXCL10和CXCL11在体外和体内对炭疽芽孢杆菌具有直接的抗菌作用。为了确定CXCL10的营养细胞靶点，我们筛选了一个炭疽杆菌转座子突变文库，发现编码广泛保守的原核ABC转运蛋白跨膜蛋白的ftsX的破坏导致了CXCL10的抗性表型。在炭疽杆菌中缺失ftsX基因（即DftsX）导致营养细胞对CXCL10产生抗性，而ftsX的补充恢复了CXCL10的敏感性。相比之下，DftsX孢子仍然对CXCL10敏感，这表明孢子具有不同的CXCL10靶点。为了进一步研究FtsX以及其他炭疽芽胞杆菌CXCL10靶点的作用，我们提出了三个具体目标：1)确定FtsX在营养细胞对CXCL10易感性中的作用；2)鉴定CXCL10的孢子靶点；3)确定CXCL10在体内感染过程中孢子和营养细菌靶点的作用。这些研究将为开发创新的治疗策略提供关键基础，这些策略不仅可以治疗炭疽芽孢杆菌引起的感染，还可以治疗一系列致病性的、潜在的多重耐药微生物。