The Development of Novel Acute Myocardial Infarction Therapeutics Using Metabolomics and High-Throughput Screening

摘要 缺血-再灌注损伤是急性心肌梗死（AMI）的基础病理。巧合的是， 当前的AMI治疗具有促进再灌注的共同目标，并且在这样做的过程中， 细胞死亡。因此，需要限制再灌注诱导的损伤的新疗法。 再灌注诱导损伤的许多病理性细胞事件可归因于代谢适应不良 重塑一种特定的代谢物是琥珀酸盐，其在缺血期间积累。后 再灌注后，琥珀酸在电子传递链中被复合物（Cx）II消耗，产生反应性的 Cx I处的氧物种。这种反向电子传递（RET）似乎是IR损伤的主要贡献者， 最近，已经提出预防缺血性琥珀酸积累作为一种新的心脏保护策略。 有趣的是，缺血性琥珀酸积累似乎是一种进化上保守的现象， 提示在低氧耐受性中的潜在作用。这些明显矛盾的观察结果导致了 我们中心假设的发展：虽然再灌注时琥珀酸氧化对IR损伤有害， 琥珀酸积累有益于缺血性线粒体功能。 在我们的初步数据中，高通量筛选将去甲尼古丁确定为心脏保护剂。降烟碱 在IR损伤的灌注心脏模型中改善IR后心脏功能并减小梗死面积。降烟碱 抑制Cx I活性，并减少再灌注时琥珀酸的消耗，表明抑制RET可能 是去甲烟碱诱导的保护机制。 总的来说，这个项目将调查心脏代谢的一个未充分探索的领域-代谢适应 并利用这些见解来开发新的AMI治疗方法。

ABSTRACT Ischemia-reperfusion (IR) injury is the underlying pathology of acute myocardial infarction (AMI). Paradoxically, current AMI therapies have the common goal of promoting reperfusion and, in doing so, trigger events that lead to cell death. As a result, there is a need for new therapeutics that limit reperfusion-induced injury. Many of the pathologic cellular events of reperfusion-induced injury can be attributed to maladaptive metabolic remodeling. One particular metabolite of interest is succinate, which accumulates during ischemia. Upon reperfusion, succinate is consumed in the electron transport chain by Complex (Cx) II, generating reactive oxygen species at Cx I. This reverse electron transport (RET) appears to be a major contributor to IR injury, and recently prevention of ischemic succinate accumulation has been proposed as a novel cardioprotective strategy. Interestingly, ischemic succinate accumulation appears to be an evolutionarily conserved phenomenon, suggesting a potential role in hypoxic tolerance. These apparently contradictory observations led to the development of our central hypothesis: while succinate oxidation at reperfusion is detrimental to IR injury, succinate accumulation is beneficial for ischemic mitochondrial function. In our preliminary data, high-throughput screening identified nornicotine as a cardioprotective agent. Nornicotine improved post-IR cardiac function and reduced infarct size in a perfused heart model of IR injury. Nornicotine inhibited Cx I activity, and reduced succinate consumption at reperfusion, suggesting that inhibition of RET might be the mechanism of nornicotine-induced protection. Overall, this project will investigate an underexplored area of cardiac metabolism – metabolic adaptations throughout ischemia – and use these insights to develop novel AMI therapeutics.