Role of Oxidative Stress in Post-MI Cardiac Failure Associated with Diabetes

描述（由申请人提供）：糖尿病（DM）患者在心肌梗死（MI）后的死亡率高于非糖尿病患者。糖尿病性心肌梗死患者的高死亡率已被证明主要是由于心力衰竭（HF）发生率的增加。鉴于美国儿童和成人糖尿病患病率的爆炸性增长，心血管疾病的发病率和死亡率很可能在这一高危人群中继续增加。我们研究的长期目标是更好地了解导致心肌梗死糖尿病患者心功能下降和心衰频率升高的病理生理机制。尽管糖尿病会导致氧化应激增加，但自由基介导的氧化应激诱导心脏损伤和最终心功能障碍的机制尚不清楚。本提案的目的是阐明介导糖尿病诱导的自由基介导的脂质过氧化对心脏功能的有害影响的下游潜在机制，并利用这一知识开发新的治疗方法。我们的初步数据显示，8-iso-PGF21（一种脂质过氧化异前列腺素途径的产物，也是氧化应激的敏感标志物）的水平在糖尿病心肌梗死后的心脏中明显高于非糖尿病心脏。我们认为，8-iso-PGF21和异酮（IsoKs）都是由脂质氧化形成的反应性脂质，在心肌梗死后糖尿病心肌氧化应激损伤和由此导致的HF的更大倾向中发挥了重要作用。该项目的具体目标是：1)确定心肌梗死后糖尿病心脏对血管活性F2-IsoPs之一8-iso-PGF21 （15-F2t-IsoP）的功能反应及其作用机制；2)测量心肌形成和IsoK蛋白加合物的定位，并利用蛋白质组学和氧印迹分析确定糖尿病心肌梗死后心脏中蛋白质氧化的特异性靶点；3)通过抗氧化剂和IsoK清除剂治疗糖尿病心肌梗死后心脏免受氧化性HF的影响。所有的研究将使用链脲佐菌素（STZ）糖尿病大鼠在一个建立的大鼠模型中进行，该模型是由冠状动脉结扎引起的心肌梗死。注射STZ后，大鼠出现高血糖、排尿过多、体重减轻等症状，与人类1型糖尿病相似。将采用广泛的多学科方法，包括多种技术（综合生理学、蛋白质化学、生物化学、免疫组织化学、蛋白质组学、病理学和组织学），并将分子水平上的蛋白质组学和生化信息与整个动物水平上的生理信息相结合。这种分子生理学策略将产生与生理学相关的新信息。

DESCRIPTION (provided by applicant): Patients with Diabetes Mellitus (DM) have a higher incidence of death after myocardial infarction (MI) than do non-diabetic patients. The excess mortality of diabetic MI patients has been demonstrated to result primarily from an increased incidence of heart failure (HF). Given the explosive gain in the prevalence of diabetes among both children and adults in the United States, it is likely that the incidence of cardiovascular disease and mortality will continue to increase in this high-risk population. The long-term goals of our studies is to better understand the pathophysiological mechanisms that lead to depressed cardiac function and a higher frequency of HF among diabetic patients with MI. Although there is a state of increased oxidative stress conferred by diabetes, the mechanisms by which free radical-mediated oxidative stress induces cardiac damage and ultimately cardiac dysfunction remains unclear. The objective of this proposal is to elucidate the downstream underlying mechanisms that mediate the deleterious effects of diabetes-induced free radical- mediated lipid peroxidation on heart function and to use this knowledge to develop novel therapies. Our preliminary data has shown that the levels of 8-iso-PGF21, a product of the isoprostane pathway of lipid peroxidation and sensitive marker of oxidative stress, are significantly greater in diabetic versus non-diabetic post-MI hearts. We propose that 8-iso-PGF21 and isoketals (IsoKs), both reactive lipid species formed from oxidation of lipids, play a fundamental role in the greater propensity of diabetic myocardium for oxidative stress injury and resultant HF after MI. The specific aims of the proposed project are: 1) to determine the functional response of diabetic post-MI hearts to one of the vasoactive F2-IsoPs, 8-iso-PGF21 (15-F2t-IsoP), and the mechanism underlying its actions; 2) to measure myocardial formation and localization of IsoK-protein adducts and identify cardiac-specific targets of protein oxidation in diabetic post-MI hearts using proteomic and oxyblot analyses, and 3) to rescue diabetic post-MI hearts from oxidant imposed HF by therapy with antioxidants and IsoK scavengers. All studies will be performed using the streptozotocin (STZ)-diabetic rat in a well-established rat model of HF due to MI by coronary artery ligation. The injection of STZ in rats leads to the development of hyperglycemia, excessive urination, and loss of weight, all of which mimics human type I diabetes. A broad multidisciplinary approach will be used that will encompass diverse techniques (integrative physiology, protein chemistry, biochemistry, immunohistochemistry, proteomics, pathology, and histology) and will integrate proteomic and biochemical information at the molecular level with physiological information at the whole animal level. This molecular physiologic strategy will yield novel information that is physiologically relevant. PUBLIC HEALTH RELEVANCE: This proposal will yield new insights into the molecular mechanism(s) of oxidant injury that is enhanced in the diabetic heart following a heart attack and during the resulting heart failure. In addition, the results may provide a framework for translating cardioprotective anti-oxidative therapy to the clinical arena to treat and manage oxidant-dependent cardiac complications in diabetic patients who have suffered a heart attack.