Mechanistic Studies of NAD+/NADH in Human Heart Failure

项目总结/摘要 线粒体功能障碍和能量缺乏与心脏的发育密切相关 故障（HF）。然而，确切的机制仍然知之甚少，靶向治疗是 缺乏最近，心脏NAD（H）稳态的丧失与线粒体 在HF中提出了功能障碍。NAD（H）氧化还原平衡，即NAD+/NADH比率，是一个关键的调节器 细胞代谢中的多重酶促反应。NAD+也作为沉默调节蛋白脱酰酶的共底物， ADP-核糖转移酶，和对蛋白质进行后修饰的环状ADP-核糖转移酶;包括 对能量传导和细胞信号传导很重要的酶。在先前的研究中，我们和其他人观察到， 在小鼠和人的心脏组织中降低NAD+/NADH比率和升高蛋白质乙酰化（LysAc） 晚期HF患者。重要的是，通过药理学或遗传学方法增加NAD+水平 使NAD（H）氧化还原失衡的丧失正常化，并逆转线粒体蛋白质的过度乙酰化， 在多种HF动物模型中改善心脏功能。在初步研究中，我们已经证明 口服NR补充剂显著增加全血NAD+水平，并改善外周血 单核细胞（PMBC）的氧化代谢。虽然这些研究为我们提供了 尽管我们的翻译研究取得了进展，但我们知识中的两个主要差距仍然存在， 处理。一个是没有研究解决口服NR是否会增加NAD+水平的关键问题 在HF患者的心肌中。另一种是增加NAD+水平有利于HF的机制 还不清楚因此，在这里，我们建议确定是否口服NR补充前八天， 手术可以增加NAD+水平，改善人类衰竭心肌的线粒体功能， 左心室辅助装置（LVAD）植入时间。我们假设参与者随机 NR将具有更高的心肌NAD+水平，改善线粒体功能， 与随机分配到安慰剂组的参与者相比，炎症反应。初步数据来自非- LVAD植入前NR预处理的随机初步研究表明，事实上，NR确实增加了 心肌NAD+水平，改善PBMC和心肌中的线粒体功能， PBMC中炎症反应基因表达。本申请中提出的随机研究还将 检查增加细胞内NAD+水平对线粒体和非线粒体的影响， 包括表观遗传修饰和炎症调节，以及相关的这些 心肌的变化与血液的相应变化。本研究证实了预期的 NR对人心肌的作用将代表研究NR潜力的重要进展 作为第一个心力衰竭的靶向代谢疗法。

Project Summary/Abstract Mitochondrial dysfunction and energy deficiency have been strongly implicated in the development of heart failure (HF). Yet, the exact mechanisms remain poorly understood and mitochondria-targeted therapy is lacking. Recently, a causal relationship between the loss of cardiac NAD(H) homeostasis and mitochondrial dysfunction has been proposed in HF. The NAD(H) redox balance, i.e. NAD+/NADH ratio, is a critical regulator of multiple enzymatic reactions in cell metabolism. NAD+ also functions as a co-substrate for sirtuin deacylase, ADP-ribose transferases, and cyclic ADP-ribose synthases that post-translationally modify proteins; including enzymes important for energy transduction and cell signaling. In prior studies, we and others have observed lower NAD+/NADH ratio and elevated protein acetylation (LysAc) in cardiac tissue from mice and human patients of advanced HF. Importantly, increasing NAD+ levels by pharmacological or genetic approach normalized the loss of NAD(H) redox imbalance and reversed mitochondrial protein hyperacetylation leading to improved cardiac function in multiple animal models of HF. In the preliminary studies, we have demonstrated that oral NR supplementation significantly increases whole blood NAD+ levels and improves peripheral blood mononuclear cell (PMBC) oxidative metabolism in humans. While these studies provide us the unique advantage of moving the translational research forward, two major gaps in our knowledge remain to be addressed. One is that no study has addressed the critical questions of whether oral NR increases NAD+ levels in the myocardium of HF patients. The other is that the mechanisms by which increasing NAD+ level benefit HF is unclear. Therefore, here we propose to determine whether oral NR supplementation for eight days prior to surgery can increase NAD+ levels and improve mitochondrial function in human failing myocardium obtained at the time of left ventricular assist device (LVAD) implantation. We hypothesize that participants randomized to NR will have higher myocardial NAD+ levels, improved mitochondrial function and reduced inflammatory response as compared to participants randomized to placebo. Preliminary data from a non- randomized Pilot Study of NR pretreatment prior to LVAD implantation suggest that NR does, in fact, increase myocardial NAD+ levels, improve mitochondrial function in PBMCs and myocardium, and decreases inflammatory response gene expression in PBMCs. The randomized study proposed in this application also will examine the effects of increasing intracellular NAD+ level on mitochondrial and non-mitochondrial compartments, including epigenetic modifications and regulation of inflammation, as well as correlate these changes in myocardium with corresponding changes in blood. Confirmation by this study of the anticipated effects of NR on human myocardium would represent an important advance in investigating the potential of NR as the first, mitochondria-targeted metabolic therapy in heart failure.