Xanthine Oxidase and Bioenergetic Function in Volume Overload

描述（由申请人提供）：心脏容量过载（VO）促进生物能量，结构和功能变化，导致心力衰竭。然而，心肌失代偿的机制和由此导致的VO进展到衰竭仍不清楚。结果表明，VO增加了黄嘌呤氧化酶（XO）和活性氧和活性氮（ROS/RNS）。在本提案中，我们将整合VO引起心力衰竭的两个关键基础研究成果：1)XO是VO引起心脏氧化损伤的来源，2)线粒体功能障碍在VO介导的心力衰竭病因学中的核心作用。这一概念将在有针对性的动物和人类研究中通过追求以下具体目标来进行测试。目的1将验证VO中XO活性升高通过心肌细胞线粒体功能障碍导致慢性VO大鼠左室功能障碍的假说。目的2将通过基因治疗降低大鼠急性和慢性VO的XDH，验证心肌细胞来源的XO活性对心肌细胞MMP激活和线粒体功能障碍负责的假设。目的3将验证XO抑制降低大鼠慢性ACF闭合后心肌细胞氧化应激和线粒体功能障碍，改善左室功能的假设。这些实验将利用新的基因治疗技术在大鼠身上证明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在动物细胞中使用Seahorse XF24进行。提出的动物和心肌细胞研究将确定在纯VO的慢性拉伸中，增加的XO是否是氧化应激和线粒体功能障碍的关键调节因子。如果这些研究结果是阳性的，将为在分离性VO患者中进行XO抑制的临床试验提供科学的推动力。

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.