Targeting Mitochondria in Single Ventricle Heart Disease

项目摘要 随着手术技术和围手术期管理的进步， 患有单心室先天性心脏病（SV）的患者，这些患者存活至儿童期及以后。由于 对于施加在单个体心室上的慢性压力和容量负荷，这些患者保持在 心力衰竭发生和进展的持续风险。不幸的是，我们对 衰竭的SV心脏与衰竭的小儿或成人双心室心脏有何不同。此外，过渡 对于SV心脏中发生的心力衰竭也不完全了解。这种缺乏理解的情况 SV心力衰竭的潜在机制是鉴定有效靶向治疗的主要障碍。 此外，SV的罕见性使得很难进行常规的前瞻性对照药物研究 在成人心力衰竭人群中进行，因此，治疗基于临床试验的外推 来自不同患者人群、经验或潜在的理论感知获益。 磷酸二酯酶-5抑制剂（PDE 5i），如西地那非，是这种治疗的一个实例， 越来越多地用于SV患者人群，现有证据基础有限。广泛而公平地 在SV患者中不分青红皂白地使用PDE 5i的部分原因是一些出版物表明， 结果是SV患者的小系列。最近出版的NHLBI燃料（Fontan Udenafil演习 纵向评估）试验证明400例fontan患者的次极量运动改善。这些 令人鼓舞的研究结合我们最近的出版物，证明PDE 5表达增加， 在衰竭的SV心脏中的活性表明心肌可能是PDE 5i的可行靶点。 虽然历史上在SV中使用PDE 5i的基本原理是增加肺血流量，但我们假设 衰竭的SV心肌，特别是线粒体，也是PDE 5i治疗的靶点。 我们的初步数据表明：（1）线粒体功能障碍，改变sirtuin信号，增加 SV衰竭心肌（SVHF）线粒体蛋白乙酰化;（2）线粒体反应性降低 通过电子顺磁共振（EPR）检测SV衰竭心脏中氧物质（ROS）的产生 用PDE 5i离体处理;（3）在小鼠中蛋白乙酰化降低和线粒体功能改善。 用PDE 5i离体处理的衰竭SV心脏;（4）SV非衰竭（SVNF）中线粒体功能受损 （初次移植或诺伍德样本）用PDE 5i离体处理的心脏;和（5）线粒体 在用SVHF患者血清处理的原代心肌细胞中， 通过添加PDE 5i或SIRT 3激活剂和诺昔康（HNK）改善。我们假设线粒体 功能障碍涉及SV心脏的HF转换，并且PDE 5i改善了SV心脏的线粒体功能。 以去乙酰化酶依赖的方式使SV心脏衰竭。我们建议使用人体组织和心肌细胞 模型来完成所提出的实验。这个项目的目的是了解过渡到高频 并提供临床前证据，以告知更有针对性的使用，目的是 优化临床护理和改善结果。

Project Summary With advancements in operative techniques and perioperative management, there is an increasing number of patients with single ventricle congenital heart disease (SV) that are surviving into childhood and beyond. Due to the chronic pressure and volume load placed on the single systemic ventricle, these patients remain at constant risk for the development and progression of cardiac failure. Unfortunately, very little is known about how the failing SV heart differs from the failing pediatric or adult biventricular heart. Additionally, the transition to heart failure that occurs in the SV heart is also incompletely understood. This lack of understanding in the mechanisms underlying SV heart failure are a major hurdle in the identification of effective targeted therapies. In addition, the rarity of SV makes it very difficult to perform prospective controlled drug studies as is routinely done in the adult heart failure population and as a result, treatments are based on extrapolation of clinical trials from different patient populations, anectdotal experience, or potential for theoretic perceived benefit. Phosphodiesterase-5 inhibitors (PDE5i), such as sildenafil, are an example of such a therapy that is increasingly used in the SV patient population with a limited existing evidence-basis. Widespread, and fairly indiscriminate use of PDE5i for SV patients is driven in part by several publications suggesting positive clinical results in small series of SV patients. The recently published NHLBI FUEL (Fontan Udenafil Exercise Longitudinal assessment) trial demonstrated improved submaximal exercise in 400 fontan patients. These encouraging studies combined with our recent publication demonstrating increased PDE5 expression and activity in failing SV hearts suggesting that the myocardium may be a viable target of PDE5i. While historically the rationale for the use of PDE5i in SV is to augment pulmonary blood flow, we hypothesize that the failing SV myocardium, and specifically the mitochondria, represent a target of PDE5i therapy as well. Our preliminary data demonstrate: (1) Mitochondrial dysfunction, altered sirtuin signaling, and increased mitochondrial protein acetylation in failing SV myocardium (SVHF); (2) Decreased mitochondrial reactive oxygen species (ROS) generation detected by Electron Paramagnetic Resonance (EPR) in failing SV hearts treated ex vivo with PDE5i; (3) Decreased protein acetylation and improvement in mitochondrial function in failing SV hearts treated ex vivo with PDE5i; (4) Impaired mitochondria function in SV Non-Failing (SVNF) (primary transplant or Norwood specimens) hearts treated ex vivo with PDE5i; and (5) Mitochondrial dysfunction and increased ROS in primary cardiomyocytes treated with SVHF patient serum, which is improved by the addition of PDE5i or the SIRT 3 activator, honokiol (HNK). We hypothesize that mitochondrial dysfunction is involved in the HF transition of SV hearts, and that PDE5i improves mitochondrial function in failing SV hearts in a sirtuin-dependent manner. We propose the use of human tissue and a cardiomyocyte model to complete the proposed experiments. The purpose of this project is to understand the transition to HF in the SV population and provide pre-clinical evidence to inform more targeted use of, with the goal of optimizing clinical care and improving outcomes.