OXIDATIVE STRESS/ANTIOXIDANT ENZYMES IN HEART FAILURE

心力衰竭的病理生理学机制仍不完全清楚。最近的证据表明，氧化应激在临床心力衰竭(HF)中增加，并可能参与左心功能不全的发病机制。体外和体内动物研究表明，活性氧(ROS)可产生直接的肌肉毒性作用，包括收缩功能受损和细胞死亡。在血液动力学超负荷导致心力衰竭的动物模型中，抗氧化酶活性降低，外源性抗氧化剂已被证明可以防止心力衰竭的发展。这项建议的总体目标是确定动物模型中ROS在人类心力衰竭发病机制中的作用程度。在特定的目标1中，我们将检验严重心力衰竭患者的心肌氧化应激增加的假设。心肌组织样本将在移植时从严重心力衰竭患者身上获得。心肌的氧化应激将通过测量8-异前列腺素和还原型/氧化型谷胱甘肽的比率来确定。在特定的目标2中，我们将检验严重心力衰竭患者心肌中抗氧化酶活性降低的假设。取目标1心肌组织标本，检测超氧化物歧化酶、谷胱甘肽过氧化物酶和过氧化氢酶的活性和表达。我们将研究酶活性的变化在多大程度上是由于基因表达的变化，而不是已知的抑制酶活性的翻译后修饰。在特定的目标3中，我们将检验这一假设，即在收缩性心力衰竭患者中，全身氧化应激增加，并与更快的疾病进展有关。在波士顿医学中心的心肌病诊所对100名有收缩功能障碍的患者进行随访，我们将在基线和3年内每年检测血液中的8-异前列腺素作为全身氧化应激的标志。我们将8-异前列腺素与心肌肌钙蛋白I(cTn-I)相关联，cTn-I是正在进行的心肌损害的量度，而超声心动图(LVEDD)是结构重塑的量度。在特定的目标4中，我们将检验这样的假设，即心肌中主要的超氧化物歧化酶MnSOD的多态性会导致心力衰竭患者氧化应激增加和更快的疾病进展。在目标3中研究的患者中，我们将确定是否存在与酶活性降低相关的MnSOD-9Ala/Val多态。这种多态的存在将与来自AIM 3的8-异前列腺素和重塑标记物相关。

The pathophysiology of heart failure remains incompletely understood. Recent evidence suggests that oxidative stress is increased in clinical heart failure (HF) and may contribute to the pathogenesis of left ventricular (LV) dysfunction. In vitro and in vivo animal studies indicate that reactive oxygen species (ROS) can exert direct myotoxic effects including impairment of contractility and cell death. In animal models of hemodynamic overload leading to heart failure, there is decreased antioxidant enzyme activity, and exogenous antioxidants have been shown to prevent the development of heart failure. The overall goal of this proposal is to determine the extent to which ROS in animal models contribute to the pathogenesis of human heart failure. In Specific Aim 1, we will test the hypothesis that oxidative stress is increased in the myocardium from patients with severe heart failure. Myocardial tissue samples will be obtained at the time of transplantation from patients with severe heart failure. Oxidative stress in the myocardium will be determined by measuring 8-isoprostane and the ratio of reduced/oxidized glutathione. In Specific Aim 2, we will test the hypothesis that there is decreased activity of antioxidant enzymes in the myocardium of patients with severe heart failure. In the myocardial tissue samples obtained for Aim 1, we will measure the activity and expression of superoxide dismutase, glutathione peroxidase and catalase. We will examine the extent to which changes in enzyme activity are due to changes in gene expression vs. post-translational modifications known to inhibit enzyme activity. In Specific Aim 3, we will test the hypothesis that systemic oxidative stress is increased in patients with systolic heart failure, and is associated with more rapid disease progression. In 100 patients with systolic LV dysfunction, followed in the Cardiomyopathy clinics at Boston Medical Center, we will measure 8-isoprostanes in the blood as a marker of systemic oxidative stress at baseline and annually for 3 years. We will correlate 8-isoprostanes with cardiac troponin I (cTn-I), a measure of ongoing myocardial damage and LV end-diastolic diameter by echocardiography (LVEDD), a measure of structural remodeling. In Specific Aim 4, we will test the hypothesis that polymorphisms of MnSOD, the major SOD in the myocardium, lead to increased oxidative stress and more rapid disease progression in patients with heart failure. In patients studied in Aim 3 we will determine the presence of the -9Ala/Val polymorphism of MnSOD that has been associated with reduced enzyme activity. The presence of this polymorphism will be correlated to 8- isoprostanes and remodeling markers from Aim 3.