Xanthine Oxidase and Bioenergetic Function in Volume Overload

描述(申请人提供)：心脏中的容量超负荷(VO)促进生物能量、结构和功能的变化，从而导致心力衰竭。然而，由于VO导致的心肌失代偿以及由此导致的进展到衰竭的机制仍不清楚。研究表明，VO可增加黄嘌呤氧化酶(XO)和活性氧氮物种(ROS/RNS)。在这项提案中，我们将结合两个关键的基础研究成果来研究VO所致的心力衰竭：1)XO是VO所致心脏氧化损伤的来源；2)线粒体功能障碍在VO所致心力衰竭的病因学中的核心作用。这一概念将通过在有针对性的动物和人类研究中追求以下具体目标来检验。目的1验证慢性VO中XO活性增加通过心肌细胞线粒体功能障碍导致左心功能不全的假说。目的2通过基因治疗大鼠急、慢性VO模型，验证心肌细胞源性XO活性与心肌细胞线粒体膜电位活化和线粒体功能障碍有关的假说。目的3验证慢性ACF关闭后，XO抑制可减轻心肌细胞氧化应激和线粒体功能障碍，改善左心功能的假说。这些实验将在大鼠身上利用新的基因治疗技术来证明XO在心肌细胞中的因果关系。心肌细胞线粒体功能的研究将使用海马XF24在动物细胞中进行。拟议的动物和心肌细胞研究将确定XO增加是否是纯VO慢性拉伸时氧化应激和线粒体功能障碍的关键调节因素。如果这些研究呈阳性，可能会为抑制孤立性VO患者的XO临床试验提供科学动力。 公共卫生相关性：容量超负荷模型中左心功能不全的机制尚不清楚，目前还没有推荐的药物治疗。通过临床相关动物模型的靶向研究，主要研究者提出了一个新的假设，即心肌细胞衍生的黄嘌呤氧化酶在容量超负荷时介导了线粒体的氧化损伤和左心功能不全。这些在动物身上的研究，如果呈阳性，可以为在孤立容量超负荷患者中抑制黄嘌呤氧化酶的临床试验提供科学动力。

DESCRIPTION (provided by applicant): Volume overload (VO) in the heart promotes bioenergetic, structural, and functional changes that lead to heart failure. However, the mechanisms of myocardial decompensation and the resulting progression to failure due to VO remain unclear. It is established that VO increases xanthine oxidase (XO) and reactive oxygen and nitrogen species (ROS/RNS). In this proposal we will integrate two critical basic research findings in the context of cardiac failure due to VO: 1) XO as a source of oxidative damage in the heart due to VO and 2) the central role mitochondrial dysfunction in the etiology of VO-mediated heart failure. This concept will be tested through pursuit of the following specific aims in targeted animal and human studies. Aim 1 will test the hypothesis that increased XO activity in VO causes LV dysfunction through cardiomyocyte mitochondrial dysfunction in chronic VO in rat. Aim 2 will test the hypothesis that cardiomyocyte-derived XO activity is responsible for cardiomyocyte MMP activation and mitochondrial dysfunction using gene therapy to knockdown XDH in acute and chronic VO in rats. Aim 3 will test the hypothesis that XO inhibition reduces cardiomyocyte oxidative stress and mitochondrial dysfunction and improves LV function after closure of chronic ACF in rat. These experiments will utilize novel gene therapy techniques in rats to prove cause and effect of XO in cardiomyocytes. Studies of cardiomyocyte mitochondrial function will be performed using Seahorse XF24 in animal cells. The animal and cardiomyocyte studies proposed will determine whether increased XO is a key regulator of oxidative stress and mitochondrial dysfunction in the chronic stretch of a pure VO. These studies, if positive, could provide the scientific impetus for a clinical trial of XO inhibition in patients with isolated VO. PUBLIC HEALTH RELEVANCE: Mechanisms of left ventricular dysfunction in models of volume overload are not well understood and there is currently no recommended medical therapy. Using targeted studies in a clinically relevant animal model the principal investigator addresses the novel hypothesis that cardiomyocyte-derived xanthine oxidase mediates oxidative damage of mitochondria and left ventricular dysfunction in volume overload. These studies in animals, if positive, could provide the scientific impetus for a clinical trial of xanthine oxidase inhibition in patients with isolated volume overload.