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 因社区获得性肺炎 (CAP) 住院的成年人会出现心律失常、充血性心力衰竭和/或心肌梗死，这在很大程度上导致了死亡率。我们进行了这项新颖且开创性的观察。肺炎链球菌是 CAP 的主要原因，在侵袭性肺炎球菌疾病 (IPD) 期间可以进入心肌并形成微小的充满细胞外肺炎球菌的空泡病变（即微病变）在患有 IPD 的小鼠中，心脏微病变的形成伴随着表明持续心力衰竭的异常心脏电生理学，与其他细菌引起的心脏感染形成鲜明对比，肺炎链球菌心脏微病变的形成是显着的。由于完全没有浸润的免疫细胞，为什么会发生这种情况尚不清楚，但我们发现，缺乏宿主反应无疑会导致心脏损伤。我们的初步结果支持了这一观点，并证明肺炎链球菌生物膜 (BF-Spn) 不会刺激宿主细胞的 NFκB 激活，也不会导致促炎细胞因子的产生。目标是辨别 目标 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，我们将检查心脏微损伤是否存在生物膜细胞外基质成分并测试分离的肺炎球菌。我们将测试缺乏在体外形成生物膜的能力的肺炎链球菌突变体在体内形成心脏微损伤的能力。暴露于浮游 (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病变内的肺炎链球菌是否处于免疫静止生物膜中 目标 2：表征心脏微病变内的肺炎链球菌并识别新的肺炎链球菌。我们将使用 RNA 测序来表征并比较心脏微病变中肺炎链球菌的基因表达谱与受感染小鼠血液中的基因表达谱。体内基因表达高的基因将被删除，并测试同基因突变体引起心脏微损伤的能力。这一目标将表征肺炎链球菌如何适应心脏内的生长，并以公正的方式确定干预目标。我们将测量心肌细胞对肺炎球菌溶血素、肺炎链球菌成孔毒素和细菌细胞的细胞因子/趋化因子反应和敏感性。我们将测试肺炎链球菌是否激活心肌细胞内的 NLRP3 炎性体。我们将确定肺炎链球菌溶血素的亚裂解水平是否会触发心肌细胞凋亡的内在途径。不是煽动性的节目。