Cardiac microlesion formation during invasive pneumococcal disease

侵袭性肺炎球菌疾病期间心脏微病变的形成

• 批准号: 9179589
• 负责人: Carlos J Orihuela
• 金额: $ 36.43万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-11-01 至 2019-10-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9179589
• 关键词: Abscess; Adult; Alpha Cell; Anatomy; Anti-Inflammatory Agents; Anti-inflammatory; Apoptosis; Arrhythmia; Attenuated; Bacteria; Bacterial Infections; Blood; Blood Circulation; Cardiac; Cardiac Electrophysiologic Techniques; Cardiac Myocytes; Cause of Death; Cell Death; Cell Wall; Cells; Cellular biology; Cessation of life; Communities; Congestive Heart Failure; Development; Event; Extracellular Matrix; Gene Expression; Gene Expression Profile; Genes; Goals; Growth; Heart; Heart failure; Immune; Immune response; In Vitro; Incidence; Individual; Infection; Inflammasome; Inflammatory; Intervention; Learning; Lesion; Lytic; Measures; Microbial Biofilms; Microscopic; Mus; Myocardial Infarction; Myocardium; Pathogenicity; Persons; Phenotype; Pneumococcal Infections; Pneumonia; Polymers; Predisposition; Production; Recruitment Activity; Seminal; Staphylococcal Infections; Streptococcus pneumoniae; Streptococcus pneumoniae plY protein; Technology; Testing; Therapeutic Intervention; Toll-like receptors; Toxin; Virulence; chemokine; cytokine; experience; extracellular; in vivo; killings; macrophage; mortality; mutant; novel; pathogen; permissiveness; programs; public health relevance; response; targeted treatment; transcriptome sequencing

DESCRIPTION (provided by applicant): Approximately 1/5 of adults hospitalized for community-acquired pneumonia (CAP) experience cardiac arrhythmia, congestive heart failure, and/or myocardial infarction and this contributes substantially to mortality. We have made the novel and seminal observation that Streptococcus pneumoniae, the leading cause of CAP, can enter the myocardium during invasive pneumococcal disease (IPD) and forms microscopic vacuolar lesions (i.e. microlesions) filled with extracellular pneumococci. In mice with IPD, cardiac microlesion formation was concomitant with aberrant cardiac electrophysiology indicative of ongoing heart failure. In stark contrast to cardiac infections caused by other bacteria, S. pneumoniae cardiac microlesion formation is remarkable due to the complete absence of infiltrated immune cells. Why this occurs is unknown, yet the lack of a host response is undoubtedly permissive for heart damage. We hypothesize that S. pneumoniae forms an immunoquiescent biofilm within the cardiac microlesion. Our preliminary results support this notion and demonstrate that biofilm S. pneumoniae (BF-Spn) does not incite NFκB activation from host cells nor results in the production of pro-inflammatory cytokines. Our goal is to discern the host-pathogen interactions that occur during cardiac microlesion formation and identify targets for intervention. Aim 1: Determine the requirement for biofilm formation during pneumococcal cardiac microlesion formation. We will examine cardiac microlesions for the presence of biofilm extracellular matrix components and test isolated S. pneumoniae for the biofilm phenotype. We will test the ability of S. pneumoniae mutants deficient in the ability to form biofilms in vitro for their ability to form cardiac microlesions in vivo. We will compare the cytokine and chemokine response of cardiomyocytes exposed to planktonic (P-Spn) and BF-Spn. This aim will directly test if S. pneumoniae within cardiac microlesions are in an immunoquiescent biofilm. Aim 2: Characterize S. pneumoniae within cardiac microlesions and identify novel virulence determinants required for their formation. Using RNA-sequencing we will characterize and then compare the gene expression profile of S. pneumoniae in cardiac microlesions to those in the blood of infected mice. Genes with high in vivo gene expression will be deleted and isogenic mutants tested for the ability to cause cardiac microlesions. This aim will characterize how S. pneumoniae adapts to growth within the heart and identify in an unbiased manner targets for intervention. Aim 3: Characterize the cardiomyocyte response to pneumolysin exposure. We will measure the cytokine/chemokine response and susceptibility of cardiomyocytes to pneumolysin, the S. pneumoniae pore forming toxin, and bacterial cell wall. We will test if S. pneumoniae activates the NLRP3 inflammasome within cardiomyocytes. We will determine if sub-lytic levels of pneumolysin trigger the intrinsic pathway of apoptosis in cardiomyocytes. This aim will discern if cardiomyocytes exposed to S. pneumoniae undergo a cell death program that is not inflammatory.

描述（由适用提供）：大约有1/5的成年人住院治疗社区获得的肺炎（CAP）体验心律不齐，充血性心力衰竭和/或心肌梗死，这对死亡率产生了重大贡献。我们已经做出了新的和第二个观察，即肺炎链球菌（CAP的主要原因）可以在侵入性肺炎肺炎疾病（IPD）中进入心肌，并形成微度真空病变（即微量），填充了细胞外肺炎肺炎。在具有IPD的小鼠中，心脏微观形成与异常的心脏电生理学伴随着持续的心力衰竭。与其他细菌引起的心脏感染形成鲜明对比的是，由于完全没有浸润的免疫球体，肺炎链球菌心脏微小物质形成是显着的。为什么发生这种情况是未知的，但缺乏宿主反应无疑是允许心脏损伤的。我们假设肺炎链球菌在心脏微片内形成免疫产生生物膜。我们的初步结果支持了这一概念，并证明生物膜肺炎链球菌（BF-SPN）不会促进宿主细胞的NFκB激活，也不会导致产生促炎性细胞因子。我们的目标是辨别 在心脏微观形成过程中发生的宿主 - 病原体相互作用并确定干预靶标。 AIM 1：确定在肺炎球菌心脏微观形成期间生物膜形成的需求。我们将检查心脏微粒的生物膜外基质成分，并测试分离的肺炎链球菌对生物膜表型。我们将测试肺炎链球菌突变体在体外形成生物膜的能力缺乏体内形成心脏微粒的能力的能力。我们将比较暴露于浮游生物（P-SPN）和BF-SPN的心肌细胞的细胞因子和趋化因子反应。该目标将直接测试心脏微粒中的肺炎链球菌是否为免疫产生生物膜。 AIM 2：表征心脏微粒中肺炎链球菌，并确定其形成所需的新病毒确定。我们将使用RNA测序来表征，然后比较心脏微小肺炎链球菌的基因表达谱与感染小鼠血液中的肺炎链球菌的基因表达谱。具有高体内基因表达的基因将被删除，并测试了引起心脏微片的能力的同基因突变体。该目标将表征肺炎链球菌如何适应心脏内生长并以无偏见的方式识别干预目标。 AIM 3：表征对肺炎暴露的心肌细胞反应。我们将测量心肌细胞对肺炎，肺炎链球菌形成毒素和细菌细胞壁的细胞因子/趋化因子反应和易感性。我们将测试肺炎链球菌是否激活心肌细胞内的NLRP3炎症体。我们将确定肺炎的亚乳酸水平是否触发心肌细胞中凋亡的内在途径。这个目标将辨别出暴露于肺炎链球菌的心肌细胞是否经历不炎症的细胞死亡程序。