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适应刺激自噬，抑制自噬阻止心脏保护。我们认为，自噬是许多心脏保护性条件性刺激的最终共同途径。我们提出了一个新的假设，即自噬是保护性的，因为它支持谷胱甘肽的生物合成和/或氨基酸通过自噬体膜的运输。此外，认识到NADH/NAD+比率的升高会导致复合体I产生ROS，并导致线粒体损伤和通透性转换孔开放，我们假设将NADH/NAD+比率转向氧化的干预措施，如丙酮酸或TAT-Ndi1给药，将减少ROS的产生，保持线粒体的完整性，并减少谷胱甘肽的氧化。因此，我们认为，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。这种组合将由一种快速诱导自噬形成的药剂和一种代谢保护线粒体的药剂(S)组成。我们将使用一种大鼠心脏Langendorff模型进行机制研究，该模型既有顿抑又有坏死。翻译研究将在临床相关的原位心肌顿抑和梗死猪制剂中进行评估。我们提出了四个具体目标：1)在使用TAT-Atg5K130R的大鼠Langendorff模型中，证明自噬对于条件性药物的心脏保护是必要的和充分的。2)确定自噬是否支持在药物条件下的大鼠心脏顿抑和坏死时谷胱甘肽的生物合成和/或质子泵出。3)用丙酮酸或TAT-Ndi1调节线粒体NADH水平以达到心脏保护的目的。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来最大限度地提高谷胱甘肽水平，以减少心肌顿抑和梗死范围。这些研究将建立涉及自噬、药物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：心肌顿抑和心肌梗死是经皮冠状动脉介入治疗(PCI)、修复性心脏手术和心脏移植后发病率和死亡率的主要短期和长期原因。该项目的目标是开发基于自噬过程的新疗法，以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适应现象的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.