Investigation of intrinsic factors for angiogenesis and recovery of endothelial cell injury contributed to the convalescenc of ischemic heart disease

我们之前报道过四氢生物蝶呤（BH4）是一氧化氮合酶（NOS）的重要辅助因子，对一氧化氮合酶（N0S）产生一氧化氮（NO）具有调节作用，外源性BH4可以保护细胞内BH4还原产生的活性氧（ROS）诱导的内皮细胞（EC）损伤（Ishii et al., 1998）。此外，BH4的保护作用似乎涉及活性氧清除活性和/或抗氧化活性。(石井。Shimizu et al., 1998)。BH4还能诱导血管内皮细胞体外血管生成（Shimizu, et al., 1999）。因此，BH4可能有效改善ROS诱导的缺血-再灌注等病理生理状态。首先，我们研究了BH4对浸润性多形核白细胞（PMNs）诱导的内皮细胞损伤的保护作用。内皮细胞中添加BH4可减少pmn诱导的EC损伤。其次，我们评估了PMN粘附内皮细胞在血管生成中的作用，因为在缺血组织的新生血管周围经常观察到PMN浸润。亚致死数量的PMNs在体内和体外诱导血管生成，PMNs刺激血管生成的机制可能与PMNs通过e-选择素、细胞间粘附分子- 1（icam - 1）和H_2O_2粘附内皮细胞有关。因此，BH4可能抑制缺血再灌注后的组织损伤。为此，研究BH4对大鼠胃缺血再灌注模型和大鼠心肌梗死模型的保护作用。治疗BH4可减轻缺血再灌注时胃溃疡或心肌梗死等组织损伤。这些结果表明BH4对缺血再灌注后的组织损伤具有保护作用，其保护作用的部分机制与PMNs诱导血管生成有关。

We previously reported that tetrahydrobiopterin (BH4), an essential cofactor for nitric oxide synthase(NOS), has a regulatory role in nitric oxide (NO) production by nitric oxide synthase (N0S), and exogenous BH4 protects endothelial cell(EC) injury induced by reactive oxygen species (ROS) which were produced by intracellular BH4 reduction (Ishii et al., 1998). Moreover, the protective effect of BH4 seems to involve ROS scavenging activity and/or antioxidative activity. (Ishii. et al., 1997, Shimizu et al., 1998). BH4 also induced in vitro angiogenesis in vascular endothelial cell (Shimizu, et al., 1999). Therefore, it is possible that BH4 effectively ameliorates pathophysiological state induced by ROS, such as ischemia-reperfusion. First, we investigated the protective effects of BH4 in endothelial cell injury induced by infiltrated polymorphonuclear leukocytes (PMNs). Addition of BH4 to endothelial cells reduced PMN-induced EC injury. Second, we evaluated the involvement of PMN adhesion to endothelial cells in angiogenesis, because PMN infiltration was often observed around the neovascular vessels in ischemic tissue. Sublethal numbers of PMNs induced angiogenesis in vivo and in vitro, and that mechanism of stimulation of angiogenesis by PMNs may involve the adherence of PMNs to endothelial cells via E-selectin and intercellular adhesion molecule- 1(ICAM-l), and H_2O_2. Thus it is possible that BH4 inhibits tissue injury after ischemia-reperfusion. Hence, the protective effects of BH4 were investigated in rat gastric ischemia-reperfusion model and rat cardiac infarction model. Treatment of BH4 reduced tissue injury such as gastric ulcer or cardiac infarction in ischemia-reperfusion. These results demonstrated that BH4 is able to protect tissue injury after ischemia-reperfusion and the part of mechanisms for the protective effect was related with encouragement of angiogenesis induced by PMNs.