Endothelial dysfunction in aged Trx-deficient mice.

描述（由申请人提供）：内皮功能障碍是心脏缺血-再灌注损伤的潜在分子机制，并已显示影响心肌梗死的梗死面积。心肌梗塞和其他冠心病是主要的健康问题，仅在美国就特别影响数百万老年人。这种损伤的发生部分是由于氧化应激引起的内皮功能障碍，当血管再灌注缺血的心脏组织时，氧化应激会增加。因此，调节心脏的氧化还原环境的药剂可潜在地用于治疗冠心病。出于这个原因，我们的实验室一直在表征硫氧还蛋白（Trx），这是一种内源性酶，可以减少氧化应激并再生因氧化而失活的蛋白质。结合这项研究，我们开发了两个转基因小鼠品系，改变了Trx的活性：一个（Trx-Tg）过表达的蛋白质，而其他（dnTrx-Tg）表达一个无活性的Trx，从而作为一个条件Trx敲除。当我们表征这些独特的小鼠时，我们发现老年TrxTg小鼠响应于缺血-再灌注（I/R）而免受心肌梗死，而那些缺乏Trx的小鼠，如野生型，经历广泛的心肌损伤。因此，我们假设，增加Trx活性水平可以提供保护，防止内皮功能障碍。这一假设导致了本提案的具体目标：目标1将确定Trx在I/R损伤引起的内皮功能障碍中的作用;目标2将探索这些作用的潜在机制;目标3将确定Trx是否增加线粒体超氧化物歧化酶的表达，作为保护内皮功能障碍的一个贡献者。该项目的结果将有助于我们理解心血管疾病如动脉粥样硬化中的内皮细胞功能障碍，并推动Trx作为治疗心血管疾病的真实的新治疗方法的发展，因为外源性添加的Trx被内皮细胞贪婪地摄取。 公共卫生相关性：冠心病（CHD）仍然是美国老年人群发病率和死亡率的主要原因（AHA 2006.例如，39岁以下的人口中只有0.14%被诊断患有CHD，而40岁以上的人口中有55%被诊断患有CHD。本申请中提出的研究将使用具有较高或较低硫氧还蛋白表达的转基因小鼠模型来研究硫氧还蛋白（一种内源性小蛋白）在保护免受心肌梗死中的作用。如果成功，这些研究将导致硫氧还蛋白作为治疗心力衰竭和其他与血流阻塞相关的疾病的治疗分子的临床试验。

DESCRIPTION (provided by applicant): Endothelial dysfunction is an underlying molecular mechanism in ischemia-reperfusion injury of the heart, and has been shown to affect infarct size in myocardial infarction. Myocardial infarction and other coronary heart disease are major health problem that especially affects millions of older people in the United States alone. This damage occurs in part in response to endothelial dysfunction caused by oxidative stress, which increases when blood vessels reperfused ischemic heart tissue. Thus, agents that modulate the redox environment of the heart are potentially useful for treating coronary heart disease. For this reason, our laboratory has been characterizing thioredoxin (Trx), an endogenous enzyme that can reduce oxidative stress and regenerate proteins that have been inactivated by oxidation. In conjunction with this research, we developed two transgenic mouse lines that have altered Trx activity: one (Trx-Tg) overexpresses the protein, whereas the other (dnTrx-Tg) expresses an inactive Trx and thus acts as a conditional Trx knockout. As we characterized these unique mice, we discovered that aged TrxTg mice are protected against myocardial infarction in response to ischemia- reperfusion (I/R), whereas those deficient in Trx, like wild type, undergo extensive myocardial damage. Thus, we hypothesize that increased levels of Trx activity can afford protection against endothelial dysfunction. This hypothesis leads to the Specific Aims of this proposal: Aim 1 will establish the role of Trx in endothelial dysfunction arising from I/R injury; Aim 2 will explore potential mechanisms of these effects; and Aim 3 will determine whether Trx increases the expression of mitochondrial superoxide dismutase as a contributor to protection against endothelial dysfunction. The outcomes of this project will contribute to our understanding of endothelial cell dysfunction in cardiovascular diseases such as atherosclerosis, and propel the development of Trx as a real novel therapeutic approach to treat cardiovascular disease as exogenously added Trx is avidly taken up by endothelial cells. PUBLIC HEALTH RELEVANCE: Coronary heart disease (CHD) remains a major cause of morbidity and mortality in aged American population (AHA 2006. For example, only 0.14% population under the age of 39 was diagnosed with CHD, whereas a staggering 55% of populations over the age of 40 were diagnosed with CHD. Studies proposed in this application will investigate the role of thioredoxin, an endogenous small protein in protecting against myocardial infarction using a transgenic mice model with higher or lower expression of thioredoxin. If successful, these studies will lead into clinical trial of thioredoxin as a therapeutic molecule for treatment of heart in heart failure and other diseases related to obstruction of blood flow.