Cardioprotective Actions of Hydrogen Sulfide

描述（由申请人提供）：硫化氢（H2S）最近被确定为具有多种生物活性的重要生理内源性气体信号分子。H2S由两种内源性酶，半胱硫氨酸3裂解酶（CGL）和半胱硫氨酸2合成酶（CBS）以微摩尔量产生，对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，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）损伤的理想选择。初步数据清楚地表明，生理水平的H2S可显著改善心肌梗死和左心室功能。初步数据还表明，H2S治疗可触发“早期”和“晚期”心肌预处理。我们还证明，心肌限制性CGL过表达的小鼠心肌H2S生物利用度显著增加，对心肌I-R损伤具有保护作用。提出的研究的中心假设是H2S触发心脏保护信号级联，在MI-R损伤的情况下提供强大的心脏保护。拟开展的研究将评估H2S治疗在“急性”和“慢性”药物预处理期间以及急性H2S治疗在再灌注时诱导的各种心脏保护信号。目的1：探讨ATP敏感K+通道（KATP通道）在H2S介导的心肌缺血再灌注损伤保护中的作用。体外研究将评估H2S对KATP通道激活和线粒体功能的影响。体内研究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，这些小鼠用H2S处理并进行MI-R。具体目的2：探讨抗氧化剂在h2s介导的心脏保护中的作用。研究将评估H2S对MI-R期间Nrf-2激活和氧化应激的急性和慢性影响。研究还将探讨H2S对心肌缺血再灌注前抗氧化信号通路的诱导作用。具体目的3：探讨风险通路在h2s介导的心脏保护中的作用。研究将探讨H2S对MI-R后风险通路（PI3K、Akt、PKC5和Erk 1/2）激活、下游抗凋亡信号、MPTP开放和心肌细胞死亡的影响。本研究将显著扩展我们目前对MI-R损伤的分子和细胞病理生理的认识，并为发展H2S治疗急性心肌梗死提供基础。公共卫生相关性：尽管在卫生保健方面取得了许多进步，但心血管疾病仍然是美国的头号杀手，急性心肌梗死（即心脏病发作）每年影响近110万人，在美国每年造成约22万人死亡。拟议的研究将评估一种新型治疗剂（即硫化氢）在急性心肌梗死临床相关和高度可转化的实验模型系统中的疗效。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。进一步的研究将检验一种关键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。拟议的研究将显著推进我们目前对心脏病发作时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.