EET-Induced Cardioprotection: Role of Opioids and Nitric Oxide (NO)

描述（由申请人提供）：心血管疾病（CVD）是美国的头号死因，缺血性心脏病是CVD患者死亡率的首要原因。大多数患有缺血性心脏病的个体都有冠状动脉阻塞，心脏组织缺乏灌注（缺血），导致心肌损伤和再灌注后的进一步损伤。花生四烯酸（AA）、11，12-和14，15-环氧二十碳三烯酸（E3）的新型CYP-环氧合酶代谢物在缺血期间特别是在再灌注后增加。内源性产生的雌二醇和外源性给予雌二醇在犬、大鼠和小鼠心脏中产生显著的心脏保护作用;然而，这些有益作用的机制仍不清楚。基于有趣的初步数据，阿片受体和一氧化氮（NO）释放可能是EET介导的心脏保护作用的2个主要参与者。本研究将利用大鼠和一氧化氮合酶（NOS）亚型的基因敲除小鼠以及心肌细胞和心脏成纤维细胞的细胞模型来深入阐明EET诱导的心脏保护作用的关键因素。待检验的假设是，在缺血/再灌注时，从心肌细胞和心脏成纤维细胞释放的E2是有效的心脏保护剂，其诱导内源性NO的进一步释放以产生其有益作用。具体而言，我们将（1）确定一氧化氮（NO）是EET诱导的大鼠和小鼠完整心脏和心肌细胞心脏保护的介质。将使用大鼠和NOS敲除小鼠和心肌细胞（H9 c2细胞）来证明EET诱导的心脏保护是通过NO信号传导途径介导的。将鉴定NOS同工型（eNOS、nNOS或iNOS）及其由ENO激活的信号传导途径。(2)确定心脏成纤维细胞在释放E2和可能的NO中发挥作用，作为调节因子保护心肌细胞免受缺氧/复氧损伤。(3)确定在心脏保护作用中，两种主要的心脏保护因素（Ehrs和阿片类药物）之间是否发生串扰。重要的是，E2很容易被可溶性环氧化物水解酶（sEH）水解为二羟基二十碳三烯酸（DHE 2），这对心肌梗死面积没有影响。这一发现表明，具有上级药代动力学的新型合成EET类似物可能代表比sEH抑制剂和不稳定的EET更好的治疗靶点。新合成的长效EET类似物将用于阐明EET的信号通路并减少梗死面积。作为这一领域的领导者，鉴定内源性雌二醇的新型稳定类似物将是该项目的主要目标，并在心脏损伤的细胞和整体动物模型中证明其强大的抗缺血和抗炎作用。长期目标是获得具有多个治疗靶点的新型内源性系统的更好表征，这可能表明联合治疗可以更好地治疗缺血/再灌注损伤。

DESCRIPTION (provided by applicant): Cardiovascular disease (CVD) is the number one cause of death in the United States and ischemic heart disease is the leader in mortality among patients with CVD. Most individuals with ischemic heart disease have blocked coronary arteries and cardiac tissue has a lack of perfusion (ischemia), resulting in myocardial damage and further injury following reperfusion. The novel CYP-epoxygenase metabolites of arachidonic acid (AA), 11,12- and 14,15-epoxyeicosatrienoic acids (EETs) are increased during ischemia and particularly following reperfusion. Endogenously produced EETs and exogenously administered EETs produce marked cardioprotective effects in dog, rat and mouse hearts; however, the mechanisms responsible for these beneficial effects remain unclear. Based on intriguing preliminary data, opioid receptors and nitric oxide (NO) release may be 2 major players in EET-mediated cardioprotection. This study will utilize rats and genetic knockout mice of nitric oxide synthase (NOS) isoforms as well as cellular models of cardiomyocytes and cardiac fibroblasts to elucidate in depth, the key contributing factors responsible for EET-induced cardioprotection. The hypothesis to be tested is that upon ischemia/reperfusion, EETs released from cardiomyocytes and cardiac fibroblasts are potent cardioprotective agents that induce the further release of endogenous NO to produce their beneficial effects. Specifically, we will (1) determine that nitric oxide (NO) is a mediator of EET-induced cardioprotection in intact rat and mouse hearts and cardiomyocytes. Both rats and NOS knockout mice and cardiomyocytes (H9c2 cells) will be used to demonstrate that EET-induced cardioprotection is mediated via a NO signaling pathway. NOS isoforms (eNOS, nNOS or iNOS) and their signaling pathways activated by the EETs will be identified. (2) Determine that cardiac fibroblasts play a role in releasing EETs and possibly NO as regulatory factor(s) to protect cardiomyocytes from hypoxia/reoxygenation injury. (3) Determine if cross-talk occurs between the two major cardioprotective factors, EETs and opioids, in cardioprotection. Importantly, EETs are readily hydrolyzed by soluble epoxide hydrolase (sEH) to dihydroxyeicosatrienoic acids (DHETs) which have no effect on myocardial infarct size. This finding suggests that novel synthetic EET analogs with superior pharmacokinetics may represent better therapeutic targets than sEH inhibitors and labile EETs. The newly synthesized longer-acting EET analogs will be used to elucidate signaling pathways of the EETs and to reduce infarct size. As leaders in the this field, identification of novel stable analogs of endogenous EETs will be a major goal of this project as well as demonstrating their powerful anti-ischemic and anti-inflammatory actions in cellular and whole animal models of cardiac injury. The long term goal is to obtain better characterization of a novel endogenous system with multiple therapeutic targets that may suggest combined therapy for better treatment of ischemia/reperfusion injury.