NITRIC OXIDE AND CHAGASIC HEART DISEASE

一氧化氮和恰加什心脏病

• 批准号: 2673079
• 负责人: MURRAY WITTNER
• 金额: $ 28.21万
• 依托单位: ALBERT EINSTEIN COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-07-01 至 2001-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2673079
• 关键词: Trypanosoma cruzi; cell adhesion molecules; cytokine; cytotoxicity; disease /disorder etiology; electrocardiography; gene expression; heart function; host organism interaction; laboratory mouse; magnetic resonance imaging; microcirculation; mixed tissue /cell culture; myocardium disorder; nitric oxide; trypanosomiasis

The etiology of chagasic heart disease is multifactorial resulting from compromised microcirculation and the direct invasion of the myocardium by, T. cruzi; both of which may lead to an inflammatory response. In recent years we delineated some of the factors associated with the pathogenesis of T. cruzi-induced heart disease. We have demonstrated that T. cruzi causes expression of iNOS, TNF-alpha and lL-1beta in the myocardium and that infection of cultured cardiac myocytes causes an increase in NO and a decrease in beat rate. Therefore, on the basis of these in vitro and in vivo observations we hypothesize that infection induces the expression of myocardial cytokines and iNOS and contributes to myocardial dysfunction. The hypothesis to be tested in this proposal is that following infection with T cruzi, the host responds by the activation of nuclear factors and cytokines resulting in upregulation of the inflammatory process and induction of iNOS causing a sustained release of toxic concentrations of NO which profoundly alters myocardial function. T. cruzi infection of endothelial cells and cardiac myocytes leads to expression of vascular adhesion molecules and iNOS by activation of IkappaB-alpha (NF-kappaB). We plan to study the mechanism whereby T. cruzi activates this pathway and the specificity of NF-kappaB activation in the transcription of those cytokines that upregulate the inflammatory response and iNOS expression. We hypothesize that the expression of iNOS and the increased synthesis of NO resulting from the activation of NF-kappaB causes cardiac myocyte dysfunction and cell death. Accordingly, using an in vitro model we will examine the influence of T. cruzi infection on cardiac myocytes. Upregulatory vs downregulatory cytokines will be studied and the influence of iNOS expression on cardiac myocyte contractility and cell death will be determined. In addition, we will employ in vitro co- culture techniques to test the hypothesis that T. cruzi infection of macrophages, vascular smooth muscle or endothelial cells results in NO- mediated altered contractility in adjacent cardiac myocytes cells. We will examine the kinetics of myocardial cytokines expression in T. cruzi-infected mice. We believe that expression of myocardial cytokines results in cardiac dysfunction which will be assessed by the administration of specific antibodies and the utilization of cytokine knock out mice. We will examine the kinetics of myocardial iNOS expression in T. cruzi-infected mice and the significance of iNOS in influencing myocardial function in acute and chronic infection will be assessed by utilizing verapamil, inhibitors of NOS, and the iNOS-/- (KO) mouse model. The consequences of myocardial cytokine and iNOS expression on "down-stream" events will be determined by pathological, biochemical and functional studies (ECG, gated MRI).

恰加斯心脏病的病因是多因素造成的 微循环受损和心肌的直接侵袭 作者：T. cruzi；这两者都可能导致炎症反应。在 近年来，我们描述了一些与 克氏锥虫引起的心脏病的发病机制。我们已经证明了 克氏锥虫引起 iNOS、TNF-α 和 IL-1β 的表达 心肌并且培养的心肌细胞的感染会导致 NO 增加，心率下降。因此，基于 这些体外和体内观察结果我们假设感染 诱导心肌细胞因子和 iNOS 的表达并有助于 导致心肌功能障碍。本提案要检验的假设 感染克氏锥虫后，宿主的反应是 核因子和细胞因子的激活导致上调 炎症过程和诱导型一氧化氮合酶（iNOS）的诱导，导致持续的 释放有毒浓度的一氧化氮，深刻改变 心肌功能。内皮细胞的克氏锥虫感染和 心肌细胞导致血管粘附分子的表达 通过激活 IkappaB-alpha (NF-kappaB) 诱导一氧化氮合酶 (iNOS)。我们计划研究 T. cruzi 激活该途径的机制及其特异性 NF-κB 激活在那些细胞因子转录中的作用 上调炎症反应和 iNOS 表达。我们 假设 iNOS 的表达和合成的增加 NF-κB 激活产生的 NO 导致心肌细胞 功能障碍和细胞死亡。因此，我们使用体外模型 将检查克氏锥虫感染对心肌细胞的影响。 将研究上调与下调细胞因子，并 iNOS表达对心肌细胞收缩力及细胞的影响 死亡将被确定。此外，我们将采用体外共 培养技术来检验克氏锥虫感染的假设 巨噬细胞、血管平滑肌或内皮细胞导致 NO- 介导邻近心肌细胞的收缩性改变。我们 将检查 T 中心肌细胞因子表达的动力学。 克鲁兹感染的小鼠。我们认为心肌细胞因子的表达 结果导致心脏功能障碍，将由 特异性抗体的施用和细胞因子的利用 消灭老鼠。我们将检查心肌 iNOS 的动力学 克氏锥虫感染小鼠中 iNOS 的表达及其意义 急性和慢性感染时对心肌功能的影响 通过使用维拉帕米、NOS 抑制剂和 iNOS-/- 进行评估 (KO)小鼠模型。心肌细胞因子和 iNOS 的后果 “下游”事件的表达将由病理、 生化和功能研究（心电图、门控 MRI）。