Cytochrome P4501A1 and Vascular Injury

描述(申请人提供)：全球有超过10亿人吸烟。此外，据估计，仅在美国就有至少1.25亿儿童和不吸烟的成年人暴露在二手烟中。主动和被动暴露于烟草烟雾(TS)是包括高血压在内的心血管疾病的主要危险因素。TS引起的心血管损伤在一定程度上是由氧化应激介导的。虽然TS是自由基的来源，但它也激活了产生活性氧物种(ROS)的内源途径。一种酶是ROS的重要来源，并且在TS的化学物质高度诱导的血管系统中是细胞色素P4501A1(CYP1A1)。虽然细胞色素P4501A1的诱导在TS诱导的肿瘤中的作用已被广泛研究，但尚未有研究探讨内皮细胞CYP1A1诱导在体内TS诱导的血管功能障碍和血流动力学改变中的作用。由于TS是一种高度复杂的化学混合物，很难剖析出任何单一的下游途径的贡献或机制。为了应对这一挑战，我们开发了一种新型的转基因小鼠模型，允许在血管中有条件地过度表达CYP1A1，以应对这一创新提议，即在体内诱导CYP1A1是血管功能障碍和高血压的独立危险因素。我们的新的初步数据显示，仅在内皮细胞中过度表达CYP1A1会导致高血压，而小鼠暴露于TS中的单个化学物质可能会导致肾素-血管紧张素系统(RAS)的激活，RAS是血管功能和血压的主要调节因子。因此，我们将检验这一假设，即在血管内皮细胞中过度表达CYP1A1显著增加ROS，从而导致血管功能障碍和血管紧张素(Ang)II依赖性高血压。我们将通过两个目标来检验这一假说：(目标1)通过多次测量ROS和通过无线电遥测测量血压来确定ROS和Ang II在由CYP1A1诱导的高血压中的作用；(2)通过使用抗氧化剂或Ang II受体阻滞剂的治疗来测量血压；(目标2)通过评估血压升高之前体外肠系膜动脉的内皮依赖性扩张和收缩，阐明内皮细胞CYP1A1过度表达干扰血管功能的机制。这项建议将确定在多大程度上诱导内皮细胞CYP1A1是体内血管功能障碍和血流动力学改变的独立介质，并将阐明其作为预防主动和被动TS暴露引起的血管疾病的药物靶点的潜力。 公共卫生相关性：吸烟或接触二手烟的人患心血管疾病的风险要高得多，包括冠心病、外周血管疾病和中风。烟草烟雾中含有的化学物质会增加血管细胞中细胞色素P4501A1的表达。这种酶是活性氧的重要来源，可导致血管损伤。因此，为了确定该酶的诱导在多大程度上介导血管损伤，并阐明其作为预防烟草烟雾暴露所致血管疾病的药物靶点的潜力，我们开发了一种新的转基因小鼠模型，该模型允许细胞类型特异性的CYP1A1过表达。

DESCRIPTION (provided by applicant): More than one billion people worldwide smoke cigarettes. In addition, it is estimated that there are at least 125 million children and non-smoking adults exposed to secondhand smoke in the U.S. alone. Both active and passive exposure to tobacco smoke (TS) is a major risk factor for cardiovascular disease, including hypertension. Cardiovascular injury induced by TS is mediated, in part, by oxidative stress. While TS is a source of free radicals, it also activates endogenous pathways that generate reactive oxygen species (ROS). One enzyme that is a significant source of ROS and is highly induced in the vasculature by chemicals in TS is cytochrome P4501A1 (CYP1A1). While the contribution of CYP1A1 induction to TS-induced cancer has been extensively studied, there have been no studies investigating the contribution of endothelial CYP1A1 induction to TS-induced vascular dysfunction and altered hemodynamics in vivo. Since TS is a highly complex mixture of chemicals, it is difficult to dissect out the contribution or mechanism of any single downstream pathway. To tackle this challenge we have developed a novel transgenic mouse model that allows for conditional over expression of CYP1A1 in the vasculature to address the innovative proposal that CYP1A1 induction is an independent risk factor for vascular dysfunction and hypertension in vivo. Our new preliminary data show that over expression of CYP1A1 solely in endothelial cells induces hypertension and exposure of mice to an individual chemical in TS may lead to activation of the renin-angiotensin system (RAS), a major regulator of vascular function and blood pressure. Thus, we will test the hypothesis that over expression of CYP1A1 in vascular endothelium significantly increases ROS which induce vascular dysfunction and angiotensin (Ang) II-dependent hypertension. This hypothesis will be tested in two aims where we will (Aim 1) establish the contribution of ROS and Ang II to hypertension induced by CYP1A1 over expression in vascular endothelium by multiple measurements of ROS and by measuring blood pressure with radiotelemetry 1 treatments with antioxidants or an Ang II receptor blocker, and (Aim 2) elucidate the mechanism by which endothelial CYP1A1 over expression disrupts vascular function independently of increases in blood pressure by evaluating endothelial-dependent dilation and constriction in mesenteric arteries ex vivo prior to increases in blood pressure. This proposal will establish the degree to which induction of endothelial CYP1A1 is an independent mediator of vascular dysfunction and altered hemodynamics in vivo and will elucidate its potential as a drug target to prevent vascular disease induced by both active and passive TS exposure. PUBLIC HEALTH RELEVANCE: Individuals that smoke cigarettes or are exposed to secondhand smoke are at much higher risk for developing cardiovascular disease, including coronary heart disease, peripheral vascular disease, and stroke. Tobacco smoke contains chemicals which increase the expression of cytochrome P4501A1 in the cells that line the blood vessels. This enzyme is a significant source of reactive oxygen species, which can cause vascular injury. Thus, to establish the degree to which induction of this enzyme mediates vascular injury and to elucidate its potential as a drug target to prevent vascular disease induced by exposure to tobacco smoke, we developed a novel transgenic mouse model that allows for cell type-specific over expression of CYP1A1.