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（由申请人提供）：大约1/5的因社区获得性肺炎（CAP）住院的成人会出现心律失常、充血性心力衰竭和/或心肌梗死，这是导致死亡的主要原因。我们已经进行了新的和开创性的观察，肺炎链球菌，CAP的主要原因，可以进入心肌在侵袭性肺炎球菌病（IPD），并形成微观空泡病变（即微病变）充满细胞外肺炎球菌。在患有IPD的小鼠中，心脏微病变形成伴随着指示持续心力衰竭的异常心脏电生理。与其他细菌引起的心脏感染形成鲜明对比的是，S。由于完全不存在浸润的免疫细胞，因此肺炎克雷伯氏菌的心脏微损伤形成是显著的。发生这种情况的原因尚不清楚，但缺乏宿主反应无疑是允许心脏损伤的。我们假设S.肺炎链球菌在心脏微损伤内形成免疫静止生物膜。我们的初步结果支持这一观点，并表明生物膜S。肺炎链球菌（BF-Spn）不引起宿主细胞NFκB活化，也不导致促炎细胞因子的产生。我们的目标是辨别 在心脏微损伤形成期间发生的宿主-病原体相互作用，并确定干预目标。目的1：确定肺炎球菌心脏微损伤形成过程中生物膜形成的要求。我们将检查心脏微病变的生物膜细胞外基质成分的存在和测试分离的S。pneumoniae的生物膜表型。我们将测试S的能力。肺炎克雷伯氏菌突变体在体外形成生物膜的能力缺陷，因为它们在体内形成心脏微损伤的能力。我们将比较细胞因子和趋化因子反应的心肌细胞暴露于缺氧（P-Spn）和BF-Spn。这一目标将直接检验S。在心脏微病变内的肺炎链球菌处于免疫静止生物膜中。目标2：表征S。肺炎在心脏微病变，并确定其形成所需的新的毒力决定因素。利用RNA测序，我们将表征并比较S. pneumoniae在心脏微病变中的作用与感染小鼠血液中的作用相似。将删除体内高基因表达的基因，并测试同基因突变体引起心脏微病变的能力。这一目标将描述S。肺炎适应心脏内的生长，并以公正的方式确定干预目标。目的3：表征心肌细胞对肺炎球菌溶血素暴露的反应。我们将测量细胞因子/趋化因子反应和心肌细胞对肺炎链球菌溶血素的敏感性。肺炎孔形成毒素和细菌细胞壁。我们将测试S。肺炎链球菌激活心肌细胞内的NLRP 3炎性体。我们将确定肺炎球菌溶血素的亚裂解水平是否触发心肌细胞凋亡的内在途径。这一目标将辨别心肌细胞是否暴露于S。肺炎杆菌经历非炎性的细胞死亡程序。