Autophagy, Adenosine and Pyruvate Protection During Heart Surgery

描述（由申请人提供）：我们有证据表明心脏保护药物和缺血预处理刺激自噬，抑制自噬会阻断心脏保护。我们认为自噬是许多心脏保护性条件刺激的最终共同途径。我们提出了一个新的假设，自噬是保护性的，因为它支持谷胱甘肽的生物合成和/或氨基酸运输通过自噬体膜。此外，认识到升高的NADH/NAD+比率导致复合物I产生ROS，并导致线粒体损伤和渗透性转换孔开放，我们假设将NADH/NAD+比率向氧化转变的干预措施，如丙酮酸盐或Tat-Ndi 1给药，将减少ROS产生，保持线粒体完整性，并减少谷胱甘肽的氧化。因此，我们建议增加自噬和调节NADH/NAD+比率的药物组合将提供最大的心脏保护。该组合将由快速诱导自噬体形成的药剂和代谢保护线粒体的药剂组成。我们将使用大鼠心脏Langendorff模型进行机制研究，包括顿抑和坏死。将在临床相关的原位心肌顿抑和梗死猪制备物中评价转化研究。我们提出四个具体目标：1）使用Tat-Atg 5 K130 R在大鼠Langendorff模型中证明自噬对于通过调节剂的心脏保护是必要且充分的。2)确定自噬是否支持谷胱甘肽生物合成和/或质子泵在缺氧条件大鼠心脏遭受顿抑和坏死。3)在大鼠心脏中使用丙酮酸盐或Tat-Ndi 1调节线粒体NADH水平以实现心脏保护，使用休克和坏死模型。4)在临床相关的原位猪制备物中，优化自噬的上调并使用预处理剂和丙酮酸盐或Tat-Ndi 1最大化谷胱甘肽水平，以减少心肌顿抑和梗死面积。这些研究将建立涉及自噬和药理学调节和代谢干预的基本机制。这些知识将使我们能够优化人类的心脏保护方案。公共卫生相关性：心肌顿抑和梗死是经皮冠状动脉介入治疗（PCI）、心脏修复手术和心脏移植后的主要短期和长期发病率和死亡率的原因。该项目的目标是开发新的疗法，以增加心脏对缺血的耐受性的基础上的自噬过程。这将需要集中在最近的研究结果，涉及自噬作为一个最终的共同途径，许多药物已知的模拟缺血预处理的现象。

DESCRIPTION (provided by applicant): We have evidence that cardioprotective drugs and ischemic preconditioning stimulate autophagy and that inhibition of autophagy blocks cardioprotection. We suggest that autophagy is the final common pathway for many cardioprotective conditioning stimuli. We propose a novel hypothesis that autophagy is protective because it supports glutathione biosynthesis and/or amino acid transport across the autophagosomal membrane. Also, recognizing that an elevated NADH/NAD+ ratio results in ROS production from Complex I, and leads to mitochondrial damage and permeability transition pore opening, we hypothesize that interventions which shift the NADH/NAD+ ratio towards oxidation, such as pyruvate or Tat-Ndi1 administration, will decrease ROS production, preserve mitochondrial integrity, and decrease the oxidation of glutathione. Thus, we propose that a combination of agents that increase autophagy and modulate the NADH/NAD+ ratio will provide maximal cardioprotection. This combination will consist of an agent that briskly induces autophagosomal formation and an agent(s) that metabolically protects mitochondria. We will perform mechanistic studies using a rat heart Langendorff model of both stunning and necrosis. Translational studies will be evaluated in clinically relevant in situ myocardial stunning and infarction porcine preparations. We propose four specific aims: 1) Demonstrate that autophagy is necessary and sufficient for cardioprotection by conditioning agents in the rat Langendorff model using Tat-Atg5K130R. 2) Determine whether autophagy supports glutathione biosynthesis and/or proton pumping in pharmacologically conditioned rat hearts subjected to stunning and necrosis. 3) Modulate mitochondrial NADH levels to achieve cardioprotection using pyruvate or Tat-Ndi1 in rat hearts using stunning and necrosis models. 4) Optimize the upregulation of autophagy and maximize glutathione levels with preconditioning agents and pyruvate or Tat-Ndi1 to reduce myocardial stunning and infarct size in clinically relevant in situ porcine preparations. These studies will establish the fundamental mechanisms involved in autophagy and pharmacological conditioning and metabolic interventions. This knowledge will enable us to optimize cardioprotective protocols in humans. Public Health Relevance: Myocardial stunning and infarction are major short and long term causes of morbidity and mortality after percutaneous coronary interventions (PCI), reparative heart surgery, and heart transplantation. The objective of this project is to develop new therapies to increase the heart's tolerance to ischemia based on the process of autophagy. This will entail focusing on recent findings which implicate autophagy as a final common pathway for many pharmacological agents known to mimic the phenomenon of ischemic preconditioning.