Cardioprotective Actions of Hydrogen Sulfide

描述（由申请人提供）：硫化氢（H2S）最近被鉴定为具有多种生物活性的生理学重要内源性气体信号分子。H2S由两种内源性酶，胱硫醚3裂解酶（CGL）和胱硫醚2合酶（CBS）以微摩尔量产生，并且对于维持心血管稳态至关重要。H2S减弱白细胞粘附，调节线粒体呼吸，并抑制细胞凋亡和氧化应激。这些生理作用是治疗心肌缺血-再灌注（MI-R）损伤的理想药物。初步数据清楚地表明，生理水平的H2S显着改善MI-R损伤和保护左心室功能。初步数据还表明，硫化氢治疗触发“早期”和“晚期”心肌预适应。我们还证明，心脏限制性CGL过表达的小鼠表现出显着增加心肌H2S的生物利用度和保护心肌I-R损伤。拟议研究的中心假设是，H2S触发心脏保护信号级联，在MI-R损伤的情况下赋予强大的心脏保护作用。拟议的研究将评估各种心脏保护信号的H2S治疗诱导的“急性”和“慢性”药理学预处理，以及在急性H2S治疗的再灌注时间。具体目标1：目的探讨ATP敏感性钾通道（KATP通道）在硫化氢介导的心肌保护中的作用。体外研究将评估H2S对KATP通道活化和线粒体功能的影响。将使用心肌细胞缺失KATP（Sur 1、Kir 6.1和Kir 6.2亚基）的基因靶向小鼠进行体内研究，这些小鼠用H2S处理并接受MI-R。具体目标2：研究抗氧化剂在H2S介导的心脏保护中的作用。研究将评估MI-R期间H2S对Nrf-2活化和氧化应激的急性和慢性影响。研究还将调查H2S对MI-R前心肌中抗氧化信号通路诱导的影响。具体目标3：研究RISK通路在H2S介导的心脏保护中的作用。研究将研究H2S对RISK通路（PI 3 K、Akt、PKC 5和Erk 1/2）激活、下游抗凋亡信号传导、MPTP开放和MI-R后心肌细胞死亡的影响。拟议的研究将显着扩展我们目前的MI-R损伤的分子和细胞病理生理学的理解，并为H2S疗法治疗急性心肌梗死的发展提供了基础。公共卫生相关性：尽管在医疗保健方面取得了许多进展，但心血管疾病仍然是美国的头号杀手，而急性心肌梗死（即，心脏病发作）每年影响近110万人，并且在美国每年造成约220，000人死亡。拟议的研究将评估一种新型治疗剂的疗效（即，硫化氢）在急性心肌梗死的临床相关和高度转化的实验模型系统中的作用。实验将确定硫化氢保护心脏免受急性心肌梗死的精确细胞机制。进一步的研究将检查一种关键的硫化氢生成酶的基因过表达对急性心肌梗死严重程度的影响。这些研究将大大推进我们目前对心脏病发作期间心肌细胞死亡机制的理解。从这些研究中获得的信息将有助于开发治疗急性心肌梗死患者的新疗法。

DESCRIPTION (provided by applicant): Hydrogen sulfide (H2S) has recently been identified as a physiologically important endogenous gaseous signaling molecule with a diverse array of biological activities. H2S is produced in micromolar quantities by two endogenous enzymes, cystathionine 3lyase (CGL) and cystathionine 2 synthase (CBS) and is critical for the maintenance of cardiovascular homeostasis. H2S attenuates leukocyte adhesion, modulates mitochondrial respiration, and inhibits both apoptosis, and oxidative stress. These physiological actions are ideal for the treatment of myocardial ischemia-reperfusion (MI-R) injury. Preliminary data clearly demonstrate that physiological levels of H2S significantly ameliorate MI-R injury and preserve left ventricular function. Preliminary data also indicate that H2S therapy triggers both "early" and "late" myocardial preconditioning. We also demonstrate that mice with cardiac-restricted CGL overexpression exhibit significantly increased myocardial H2S bioavailability and protection against myocardial I-R injury. The central hypothesis for the proposed studies is that H2S triggers a cardioprotective signaling cascade that confers robust cardioprotection in the setting of MI-R injury. The proposed studies will evaluate the various cardioprotective signals induced by H2S therapy during both "acute" and "chronic" pharmacological preconditioning as well as the during acute H2S therapy at the time of reperfusion. Specific Aim 1: To investigate the contribution of ATP sensitive K+ channels (KATP channels) in H2S- mediated cardioprotection against myocardial ischemia-reperfusion injury. In vitro studies will evaluate the effects of H2S on KATP channel activation and mitochondrial function. In vivo Studies will be performed using gene-targeted mice with cardiac myocyte deletion of KATP (Sur 1, Kir 6.1, and Kir 6.2 subunits) treated with H2S and subjected to MI-R. Specific Aim 2: To investigate the role of antioxidants in H2S-mediated cardioprotection. Studies will evaluate the acute and chronic effects of H2S on Nrf-2 activation and oxidative stress during MI-R. Studies will also investigate the effects of H2S on the induction of antioxidant signaling pathways in the myocardium prior to MI-R. Specific Aim 3: To investigate the role of the RISK pathway in H2S-mediated cardioprotection. Studies will investigate the effects of H2S on RISK pathway (PI3K, Akt, PKC5, and Erk 1/2) activation, downstream anti-apoptotic signaling, MPTP opening, and myocardial cell death following MI-R. The proposed studies will significantly extend our current understanding of the molecular and cellular pathophysiology of MI-R injury and provide the foundation for the development of H2S therapy for the treatment of acute myocardial infarction. PUBLIC HEALTH RELEVANCE: Despite numerous advances in health care, cardiovascular disease remains the number one killer in the United States and acute myocardial infarction (i.e., heart attack) affects nearly 1.1 million people every year and is responsible for approximately 220,000 deaths per year in the United States. The proposed studies will evaluate the efficacy of a novel therapeutic agent (i.e., hydrogen sulfide) in a clinically relevant and highly translational experimental model system of acute myocardial infarction. Experiments will determine the precise cellular mechanisms by which hydrogen sulfide protects the heart against acute myocardial infarction. Additional studies will examine the effects of genetic overexpression of a critical hydrogen sulfide generating enzyme on the severity of acute myocardial infarction. The proposed studies will significantly advance our current understanding of the mechanisms responsible for myocardial cell death during a heart attack. Information gained from these studies will help with the development of novel therapies for the treatment of patients suffering from acute myocardial infarction.