Gene expression responses to air pollution and modification by genetic variation

描述(申请人提供)：心脏病是美国的主要死因。2009年，与冠心病(CHD)相关的直接和间接成本估计总计1650亿美元。因此，有大量的研究需要加强我们对冠心病发病率和死亡率的危险因素的了解。流行病学研究表明，暴露于环境颗粒物(PM)空气污染与心血管发病率和死亡率的增加有关。虽然确切的机制尚不清楚，但PM水平的升高与炎症和血栓形成的循环生物标志物水平的升高有关。与PM暴露有关的相关生物途径中的基因表达与人类潜在的心脏风险增加有关的数据很少。同样，在人类中，关于个体遗传变异是否会导致与急性外周血管对颗粒性空气污染物反应相关的病理生理机制相关的基因表达发生明显变化的信息有限。这项研究的目的是评估老年冠心病患者的外周血液基因表达与空气污染暴露之间的关系，并测试核基因和线粒体基因变异对这些关系的影响，这些基因变异可能会增加心血管对空气污染的风险。由于天气、地形和交通的独特组合，空气污染在洛杉矶盆地相当重要。心血管健康和空气污染研究(CHAPS，该项目的母公司研究)显示，在洛杉矶地区易感人群中，与交通相关的PM成分与缺血性ST段压低、全身炎症和血压升高之间存在关联。来自CHAPS的体外证据表明，PM的成分诱导活性氧物种的产生。此外，最近的实验表明，PM对培养的人呼吸道上皮细胞和血管内皮细胞解毒途径中的基因表达上调。先前的体外研究表明，超细颗粒(直径0.1m)定位于线粒体并破坏线粒体。最近的一项横断面研究表明，线粒体DNA(MtDNA)拷贝数与PM暴露增加有关，表明线粒体受损。我推测，暴露于PM空气污染将与核基因表达水平的变化有关，核和线粒体基因的多态以及体细胞mtDNA突变将改变这种联系，以及先前建立的与全身炎症生物标志物的联系。我将使用Q-PCR和CHAPS队列中全血的DNA测序来检验这一假设。遗传信息可能揭示解释先前所见的重大生物标记物反应的合理的分子机制。研究这些关系可能会阐明空气污染暴露对心血管影响的潜在机制。

DESCRIPTION (provided by applicant): Heart disease is the leading cause of death in the United States. In 2009, direct and indirect costs associated with coronary heart disease (CHD) were estimated to total $165 billion. Therefore, there is substantial need for research to enhance our understanding of risk factors for CHD morbidity and mortality. Epidemiological studies have shown that exposure to ambient particulate matter (PM) air pollution is associated with increases in cardiovascular morbidity and mortality. Though exact mechanisms are unknown, elevated PM levels have been associated with increased levels of circulating biomarkers of inflammation and thrombosis. There is little data regarding gene expression in relevant biological pathways in relation to PM exposure in humans at potentially increased cardiac risk. Similarly, there is limited information in humans on whether individual genetic variation produces observable changes in gene expression relevant to pathophysiological mechanisms involved in acute peripheral vascular responses to particulate air pollutants. The aims of this study are to evaluate relations between peripheral blood gene expression and air pollution exposures in a cohort panel of elderly subjects with CHD, and to test effect modification of these relations by variants of nuclear and mitochondrial genes that may confer increased cardiovascular risk to air pollution. Air pollution is of considerable importance in the Los Angeles (LA) basin due to a unique combination of weather, topography and traffic. The Cardiovascular Health and Air Pollution Study (CHAPS, parent study of this project) has shown associations of traffic-related PM components with ischemic ST-segment depression, systemic inflammation and increases in blood pressure among a susceptible population of older adults in the LA area. In vitro evidence from CHAPS indicates that components of PM induce reactive oxygen species generation. Additionally, recent experiments showed an up regulation of genes in detoxification pathways in cultured human airway epithelial and vascular endothelial cells exposed to PM. Previous in vitro research has shown ultrafine PM (diameter <0.1 ¿m) localizes to and damages the mitochondria. A recent cross-sectional study showed mitochondrial DNA (mtDNA) copy number was associated with increased PM exposure, indicating mitochondrial damage. I hypothesize that exposure to PM air pollution will be associated with changes in nuclear gene expression levels and that polymorphisms in nuclear and mitochondrial genes and somatic mtDNA mutations will modify this association as well as the previously established associations with biomarkers of systemic inflammation. I will examine this hypothesis using q-PCR and sequencing of DNA from whole blood from the CHAPS cohort. Genetic information may reveal plausible molecular mechanisms that account for the significant biomarker responses previously seen. Investigating these relationships may elucidate potential mechanisms for the cardiovascular effects of air pollution exposure.