MOLECULAR PATHOGENESIS OF CARDIAC DYSFUNCTION

心脏功能障碍的分子发病机制

• 批准号: 6882405
• 负责人: BRETT P GIROIR
• 金额: $ 8.32万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-04-01 至 2006-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6882405
• 关键词: burns; cardiovascular disorder; cardiovascular function; cell adhesion molecules; cytokine receptors; disease /disorder model; electrocardiography; gene expression; gene targeting; genetically modified animals; heart failure; histopathology; interleukin 1; laboratory mouse; longitudinal animal study; magnetic resonance imaging; model design /development; molecular pathology; myocardial ischemia /hypoxia; myocarditis; myocardium; nitric oxide synthase; selectins; septic shock; tumor necrosis factor alpha

The goal of this proposal is to determine the molecular mechanisms of cardiac dysfunction that occurs during septic shock and following thermal trauma. Previous work has demonstrated that cardiac dysfunction is mediated by the cytokine tumor necrosis factor-alpha (TNF), which is produced locally in the myocardium by cardiac myocytes. This proposal utilizes novel molecular and genetic strategies to investigate the mechanisms of TNF's detrimental effects and to develop therapeutic approaches for TNF-related cardiac contributions. First, we will study transgenic mice in which TNF is constitutively expressed only by cardiac myocytes. These mice develop profound cardiac dysfunction, cardiomyopathy, myocarditis, and cardiac failure which mimics cardiac contractile dysfunction in humans. By breeding these transgenic animals to mice which have undergone targeted disruption of iNOS (inducible nitric oxide synthase), IRAK (IL-1 receptor associated kinase), and ICAM-1 / P-selectin, as well as by pharmacological inhibition of specific pathways, we will quantitatively determine the involvement of iNOS, IL-1, and transmigrated leukocytes in the pathogenesis of myocardial failure. Cardiac phenotype will be characterized primarily by in vitro Langendorff perfusion of isolated mouse hearts; confirmatory longitudinal analysis of function will be accomplished in vivo by ECG-gated MRI imaging. Physiologic findings will be correlated with survival, post-mortem histology, and the pattern of cardiac gene expression. Next, we will optimize the transgenic animal model by developing a binary transgene system which is cardiac specific, and regulatable by dietary tetracycline. Through this system, we will determine if the effects of TNF are related to dose and duration of expression. We will describe the cascade of secondary cytokines induced by TNF. We will also determine whether low-level, transient expression of TNF may be evolutionary adaptive, and serve a protective role against subsequent cardiac insults. By understanding the molecular mechanisms by which TNF impedes myocardial performance, it will be possible to develop specific, targeted therapeutic strategies for the treatment of sepsis, burn trauma, and other TNF-related cardiac conditions such as cardiomyopathy, myocarditis, and ischemic heart disease.

本提案的目的是确定感染性休克和热创伤后发生的心功能不全的分子机制。以前的工作已经证明，心脏功能障碍是由细胞因子肿瘤坏死因子-α（TNF）介导的，TNF是由心肌细胞在心肌中局部产生的。该建议利用新的分子和遗传策略来研究TNF的有害作用的机制，并开发TNF相关心脏贡献的治疗方法。首先，我们将研究转基因小鼠，其中TNF是组成型表达的心肌细胞。这些小鼠发生严重的心脏功能障碍、心肌病、心肌炎和心力衰竭，其模拟人类的心脏收缩功能障碍。 通过将这些转基因动物与已经经历了iNOS（诱导型一氧化氮合酶）、IRAK（IL-1受体相关激酶）和ICAM-1 /P-选择素的靶向破坏以及通过特定途径的药理学抑制的小鼠交配，我们将定量地确定iNOS、IL-1和迁移的白细胞在心肌衰竭的发病机制中的参与。 心脏表型将主要通过离体小鼠心脏的体外Langendorff灌注表征;功能的确认性纵向分析将通过ECG门控MRI成像在体内完成。生理学发现将与存活率、死后组织学和心脏基因表达模式相关。接下来，我们将通过开发心脏特异性的、可通过饮食四环素调控的二元转基因系统来优化转基因动物模型。通过这个系统，我们将确定TNF的作用是否与表达的剂量和持续时间有关。我们将描述由TNF诱导的次级细胞因子的级联反应。我们还将确定TNF的低水平瞬时表达是否可能是进化适应性的，并对随后的心脏损伤起保护作用。通过了解TNF阻碍心肌性能的分子机制，将有可能开发用于治疗脓毒症、烧伤创伤和其他TNF相关心脏疾病（如心肌病、心肌炎和缺血性心脏病）的特异性靶向治疗策略。