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，抑制自噬可阻断心脏保护。我们认为自噬是许多心脏保护条件刺激的最终共同途径。我们提出了一个新的假设，自噬具有保护作用，因为它支持谷胱甘肽的生物合成和/或氨基酸在自噬体膜上的运输。此外，认识到NADH/NAD+比值升高会导致复合体I产生ROS，并导致线粒体损伤和通透性过渡孔打开，我们假设将NADH/NAD+比值转向氧化的干预措施，如丙酮酸或Tat-Ndi1，将减少ROS的产生，保持线粒体完整性，并减少谷胱甘肽的氧化。因此，我们提出增加自噬和调节NADH/NAD+比率的药物组合将提供最大的心脏保护。这种组合将包括一种快速诱导自噬体形成的药物和一种代谢保护线粒体的药物。我们将使用大鼠心脏休克和坏死的朗根多夫模型进行机制研究。转化研究将在临床相关的原位心肌休克和梗死猪制剂中进行评估。我们提出了四个具体目标：1)利用Tat-Atg5K130R在大鼠Langendorff模型中证明自噬对调节剂的心脏保护是必要和充分的。2)确定在休克和坏死的大鼠心脏中，自噬是否支持谷胱甘肽生物合成和/或质子泵送。3)使用丙酮酸或Tat-Ndi1调节线粒体NADH水平，以实现大鼠心脏休克和坏死模型的心脏保护。4)在临床相关的原位猪制剂中，优化自噬的上调，并使用预处理剂和丙酮酸或Tat-Ndi1最大化谷胱甘肽水平，以减少心肌休克和梗死面积。这些研究将建立自噬、药理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：心肌休克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术后发病和死亡的主要短期和长期原因。本项目的目的是在自噬过程的基础上开发新的治疗方法来提高心脏对缺血的耐受性。这将需要关注最近的发现，这些发现暗示自噬是许多已知的模仿缺血预处理现象的药理学药物的最终共同途径。

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.