Myeloperoxidase and NO signaling in the vasculature

描述(申请人提供)：髓过氧化物酶(MPO) 在宿主防御反应中起着重要作用。髓过氧化物酶催化 将氯化物加到过氧化氢中，形成 氯化物种次氯酸(HOCI)次氯酸发生反应 热衷于大量的细胞靶标，包括硫醇、胺、核苷酸和 不饱和脂肪酸。最近的证据表明，MPO和Hoci对 与心血管疾病的发病机制有关。在此应用程序中，我们呈现 数据表明MPO来源的hoci有助于 通过降低一氧化氮(NO)的生物利用度而导致的内皮功能障碍。MPO 有效地与动脉壁结合，并与显著的 组织酶活性的增加。体外研究结果表明， MPO来源的Hoci减弱乙酰胆碱诱导的松弛，但不影响 NO供体引起的松弛。这些数据表明内皮细胞是一种 MPO依赖损伤的靶点。HOCI介导MPO的抑制作用 由于内皮功能障碍可以通过添加HOC 清道夫L-蛋氨酸。血管内皮细胞NO有几种成分 可被hoci修饰的合成途径，包括一氧化氮合酶(NOS III) 活性、L-精氨酸底物和一氧化氮合酶病依赖的辅因子在这 提案，我们将确定潜在的抑制作用的机制 MPO衍生的HOCI对NO的生物利用度通过1)定义MPO对 血管内皮细胞NO信号转导过程；2)L精氨酸的作用特征 衍生N-氯胺在MPO依赖的内皮细胞损伤中的作用；3)通过 确定MPO抑制剂是否预防血管内皮细胞功能障碍 大鼠脑缺血再灌流模型。依赖于hoci的修饰 L-精氨酸可能是血管内皮细胞常见的致病机制 各种心血管疾病中的功能障碍。

DESCRIPTION (provided by the applicant): The heme protein myeloperoxidase (MPO) plays an important role in the host defense response. Myeloperoxidase catalyzes the addition of chloride to hydrogen peroxide, resulting in the formation of the chlorinating species hypochlorous acid (HOCI) Hypochlorous acid reacts avidly with numerous cellular targets including thiols, amines, nucleotides and unsaturated fatty acids. Recent evidence suggests that MPO and HOCI contribute to the pathogenesis of cardiovascular disease. In this application, we present data suggesting that MPO-derived HOCI contributes to the development of endothelial dysfunction by reducing nitric oxide (NO) bioavailability. MPO effectively binds to the arterial wall and is associated with a significant increase in tissue enzymatic activity. Results of in vitro studies showed that MPO-derived HOCI impairs acetylcholine-induced relaxation but does not affect relaxation induced by an NO donor. These data suggest that the endothelium is a target of MPO-dependent injury. HOCI mediates the inhibitory effects of MPO since endothelial dysfunction could be prevented by addition of the HOC scavenger L-methionine. There are several components of the endothelial NO synthetic pathway that may be modified by HOCI including NO synthase (NOS III) activity, L-arginine substrate and NOS Ill-dependent cofactors. In this proposal, we will identify mechanisms underlying the inhibitory effects of MPO-derived HOCI on NO bioavailability by 1) defining the effects of MPO on endothelial NO signaling processes; 2) characterizing the role of L-arginine derived N-chloramines in MPO-dependent endothelial cell injury; and 3) by determining whether inhibitors of MPO prevent endothelial dysfunction in a rodent model of ischemia-reperfusion. The HOCI-dependent modification of L-arginine may represent a common pathogenic mechanism underlying endothelial dysfunction in diverse cardiovascular diseases.