Molecular Mechanism of Acrolein-Induced Vascular Toxicity: Role of PPAR gamma and

描述(由申请人提供)：丙烯醛是一种主要的环境污染物，被环境保护局(EPA)归类为高度优先的空气/水有毒物质，是一种内源性过氧化产物，与血管反应性受损有关，导致动脉粥样硬化变化的浓度与人类疾病记录的浓度或剂量类似于人类口服的总乙醛摄入量。丙烯醛介导的血管改变的确切机制尚不清楚，但可能与超氧化物歧化活性增加和抗氧化防御减弱有关。血管系统的动脉粥样硬化改变通常先于炎症的早期迹象。这个过程涉及一氧化氮(NO)和氧自由基。血管NAD(P)H氧化酶作为氧自由基的主要来源发挥着重要作用。过氧化物酶体增殖物激活受体γ(PPARγ)是一种核转录因子，通过调节炎症基因的转录来调节炎症反应。PPARγ通过转录调控NAD(P)H氧化酶的gp91Phox和p47Phox亚基，下调依赖于NAD(P)H的超氧化物的生成。炎症反应是NO和超氧化物之间的重要平衡，对血管反应的调节大多依赖于NO。因此，在丙烯醛中毒过程中，PPARγ、NAD(P)H氧化酶和NO/一氧化氮合酶系统之间可能存在相互作用。在这项研究中，我们假设丙烯醛改变了依赖于PPARγ的NAD(P)H氧化酶的调节，增加了超氧化物的产生，从而抵消了依赖于PPARγ、-NAD(P)H和依赖于NO/NOSs的抗炎反应。本研究的目的是：(1)确定PPARγ在丙烯醛诱导的血管毒性中的作用；(2)确定PPARγ在依赖NAD(P)H的超氧化物生成中的作用；(3)确定PPARγ、-NAD(P)H和-NO/NOSs在丙烯醛诱导的血管毒性中依赖的炎症调控。经丙烯醛处理的Spraogue-Dawley大鼠、gp91Phox和p47Phox基因敲除小鼠以及NOS基因敲除小鼠将被用来通过遥测和血流动力学分析来确定血压和血管反应的变化。将研究NAD(P)H氧化酶的表达、活性和超氧化物的产生。炎症标志物将通过检测IL-2、COX-1、NFkappaB和NOS进行研究。这项研究将有助于我们了解丙烯醛诱导的血管毒性的机制，从而了解动脉粥样硬化的炎症机制。非裔美国人的心血管疾病发病率较高，部分原因可能是少数族裔的社会经济地位较低，居住在环境污染物暴露较多的地区。这项研究将扩大我们对环境污染物对心血管疾病的贡献的理解，并提供关于依赖于PPARγ和NAD(P)H的炎症过程调节的可能性的信息，最终将导致更好和更特异的治疗脆弱人群心血管疾病的方法。

DESCRIPTION (provided by applicant): Acrolein a major environmental pollutant classified by the Environmental Protection Agency (EPA) as a high-priority air/water toxic and an endogenous peroxidation product has been linked to impaired vascular reactivity, leading to atherosclerotic changes at concentrations documented in human disease, or doses similar to human oral total aldehyde intake. The precise mechanism of acrolein mediated vascular alteration is not clear, but a possible association with an increased superoxide activity and reduced antioxidant defense has been proposed. Atherosclerotic changes in the vasculature are usually preceded by early signs of inflammation. This process involves nitric oxide (NO) and oxygen free radicals. Vascular NAD(P)H oxidase plays an important role as the major source of oxygen free radical generation. Peroxisome proliferator activated receptor gamma (PPARγ), a nuclear transcription factor, regulates inflammatory response via modulating the transcription of inflammatory genes. PPARγ down regulates NAD(P)H-dependent superoxide generation via transcriptional regulation of gp91phox and p47phox subunits of NAD(P)H oxidase. Inflammatory response is a crucial balance between NO and superoxide, and regulation of vascular response is mostly NO dependent. Therefore, an interaction may persist between PPARγ, NAD(P)H oxidase and NO/nitric oxide synthase (NOS) system in acrolein toxicity. In this study, we hypothesize that acrolein alters PPARγ-dependent regulation of NAD(P)H oxidase, increases superoxide generation and thus offsets the PPARγ,-NAD(P)H,- and NO/NOS-dependent anti-inflammatory responses. The aims of the study are: (1) To determine the role of PPARγ in acrolein-induced vascular toxicity, (2) To establish the role of PPARγ in NAD(P)H-dependent superoxide generation and (3) To determine the PPARγ,-NAD(P)H,- and NO/NOS-dependent modulation of inflammation in acrolein- induced vascular toxicity. Acrolein treated Sprague-Dawley rats, gp91phox and p47 phox knockout mice, and NOS knockout mice will be utilized to determine changes in blood pressure and vascular responses by telemetry and hemodynamic analysis. NAD(P)H oxidase expression, activity and superoxide generation will be investigated. Inflammatory markers will be investigated by examining IL-2, COX-1, NFkappaB and NOS. This study will allow us to understand the mechanism of acrolein-induced vascular toxicity and thus the inflammatory mechanism of atherosclerosis. Incidents of cardiovascular diseases (CVD) are higher in African- Americans and may be partially due to lower socioeconomic status of the minorities and residence in areas with increased exposure to environmental pollutants. This study will broaden our understanding of contribution of environmental pollutants to CVD, and provides information on the possibility of involvement of PPARγ-and NAD(P)H -dependent regulation of inflammatory processes which ultimately will lead to better and more specific treatments for CVD among vulnerable population.