Cardiomyocyte self-defense against Streptococcus pneumoniae

摘要： 四分之一因社区获得性肺炎(CAP)住院的成年人经历了严重的不良反应 心脏事件(MACE)。经历过Mace的人死亡的可能性是那些患有Mace的人的4-5倍 单单是肺炎。CAP的住院也与MACE和心血管相关的更高风险有关 在康复期中死亡至少5年。因此，肺炎会损害心脏，这与 住院期间和住院后的MACE和心血管相关死亡。肺炎链球菌 革兰氏阳性菌(SPN)是CAP和侵袭性疾病的主要病因。在入侵期间 肺炎球菌病(IPD)，血液中的Spn进入心肌，在那里复制， 杀死心肌细胞，损害功能。值得注意的是，在存活的动物中， 抗菌药物，Spn引起的心脏损伤导致组织重塑，具有长期的负面影响 心脏功能。因此，心脏中的肺炎球菌是心脏损害的直接影响因素，这有助于 来解释与CAP相关的MACE。 近一年来，我们实验室一直在研究Spn对心肌细胞损伤的分子基础 十年。我们的一个重要发现是，侵入心脏的Spn被心肌细胞摄取 通过网状蛋白介导的内吞作用。此外，当肺炎球菌在这些细胞内持续存在时，它们的复制和 肺炎溶血素和过氧化氢的产生会导致心肌细胞死亡。因此，我们 已经选择探索与LC3相关的吞噬作用的重要性，这是自噬的一种形式 心肌细胞自卫。我们的初步结果支持这样的假设：1)自噬保护 心脏在IPD期间；2)自噬有助于根除心脏中的细胞内细菌；3) 心肌细胞自噬在感染后维持心脏功能。通过以下途径检验这些假说 完成以下目标将促进我们对发生在宿主和病原体之间的相互作用的理解 在IPD期间的心脏中，有可能影响未来的干预策略。我们会： 目的1：确定自噬在保护心肌细胞功能和存活率中的作用 在摄取Spn之后。这将在体外使用自噬缺陷(ATG7缺失)成年小鼠来完成 心肌细胞和诱导多能干细胞来源的心肌细胞在一种新的心脏中生长 感染Spn的组织芯片。 目的2：确定自噬对心脏重构的影响。这将在体内完成，使用 感染Spn的心肌细胞特异性ATG7缺失小鼠。将使用以下方法评估心脏功能 超声心动图使感染后心脏重构的程度可以与异常相关 功能。

ABSTRACT: One-in-four adults hospitalized for community-acquired pneumonia (CAP) experiences a major adverse cardiac event (MACE). Individuals who experience MACE are 4-5 times more likely to die than those with pneumonia alone. Hospitalization for CAP is also tied to greater risk of MACE and cardiovascular-associated death in convalescence for at least 5 years. Thus, pneumonia damages the heart and this is linked to MACE and cardiovascular-associated death during and after hospitalization. Streptococcus pneumoniae (Spn), a Gram-positive bacterium, is the leading cause of CAP and invasive disease. During invasive pneumococcal disease (IPD), Spn in the bloodstream gains access to the myocardium, where they replicate, kill cardiomyocytes, and impair function. Notably, and in surviving animals that had been treated with antimicrobials, cardiac damage caused by Spn results in tissue remodeling that has long-term negative effects on heart function. Thus, pneumococci in the heart are direct effectors of cardiac damage and this helps to explain CAP-associated MACE. Our laboratory has been studying the molecular basis of cardiomyocyte damage by Spn for close to a decade. One key discovery we have made is that Spn that invade the heart are taken up by cardiomyocytes via clathrin-mediated endocytosis. Moreover, when pneumococci persist within these cells, their replication and production of pneumolysin and hydrogen peroxide results in the death of the cardiomyocyte. Accordingly, we have chosen to explore the importance of LC3-associated phagocytosis, a form of autophagy, on cardiomyocyte self-defense. Our preliminary results support the hypotheses that: 1) autophagy protects the heart during IPD; 2) autophagy contributes to the eradication of intracellular bacteria in the heart; 3) cardiomyocyte autophagy sustains cardiac function post-infection. Testing of these hypotheses via completion of the aims below will advance our understanding of the host-pathogen interactions that take place in the heart during IPD with the potential to influence future intervention strategies. We will: AIM 1: Determine the role of autophagy in protecting cardiomyocyte function and survivability following Spn uptake. This will be done in vitro using autophagy-deficient (ATG7 null) adult mouse cardiomyocytes and induced pluripotent stem cell (iPSC)-derived cardiomyocytes growing in a novel cardiac tissue chip infected with Spn. AIM 2: Determine the impact of autophagy on cardiac remodeling. This will be done in vivo using cardiomyocyte-specific ATG7 null mice infected with Spn. Cardiac function will be evaluated using echocardiography so that the extent of post-infection cardiac remodeling can be correlated to aberrant function.