Epigenetic Effects of Particles and Metals on Cardiac Health of an Aging Cohort

描述（由申请人提供）： 心血管疾病（CVD）是美国老年人死亡的主要原因。由于75岁以上的美国人的比例预计将从2000年的6%增加到2050年的11%，因此未来几年死于CVD的人数可能会急剧增加。在以前的工作中，这个研究小组证明了急性和慢性颗粒空气污染暴露与特定的心血管结果有关，例如心率变异性降低，动脉僵硬和ST段压低，导致CVD死亡率增加。 已发现DNA甲基化变化与炎症、内皮功能和动脉粥样硬化有关。对实验模型和人类的初步观察表明，空气颗粒和金属是颗粒污染的组成部分，它们会改变DNA甲基化状态。在暴露于空气颗粒和有毒金属（如砷、镉和铅）的受试者中观察到的CVD风险增加是否是由DNA甲基化模式的改变介导的尚不清楚。这项提案的目的是确定暴露于空气颗粒和有毒金属（砷，镉和铅）是否会随着时间的推移改变老年受试者的整体和/或基因特异性甲基化，从而增加CVD风险。具体而言，本提案将评估：1）暴露与Alu和LINE-1序列中的整体DNA甲基化以及特定基因中的高甲基化或低甲基化的关联ICAM-1、IFN-γ、p16参与内皮功能和动脉粥样硬化;以及2）上述总体和基因特异性DNA甲基化改变与CVD相关结果之间的关联（心率变异性，动脉粥样硬化的脉冲多普勒测量，ST段抬高/压低，炎症/内皮功能的生物标志物）。作为第二个目标，该计划将探索：1）全球或基因特异性甲基化状态是否改变了空气颗粒和有毒金属的关联（Pb、As、Cd），CVD相关终点;和2）暴露和甲基化状态之间的关联通过饮食因素的血浆水平或摄入来改变（叶酸、维生素B6和B12）、血浆同型半胱氨酸水平和DNA甲基化基因中的SNP（MTHFR、cSHMT）。该研究设计基于马萨诸塞州东部现有的700名老年受试者队列，将允许对空气颗粒、金属生物标志物、DNA甲基化模式和CVD表型进行基线和纵向分析，因此将对所有假设进行横断面和纵向检验。将对每例研究受试者在长时间跨度内采集的3份血液DNA样本进行定量DNA甲基化分析（基于亚硫酸氢盐处理DNA的PCR扩增和焦磷酸测序）。

DESCRIPTION (provided by applicant): Cardiovascular disease (CVD) is the leading cause of death among the elderly in the United States. Since the percentage of Americans over the age of 75 years is expected to increase from 6% in 2000 to 11 % in 2050, the number of persons dying from CVD will likely rise dramatically in the coming years. In previous work, this team of investigators demonstrated that acute and chronic particulate air pollution exposures are associated with specific cardiovascular outcomes, such as decreased heart rate variability, arterial stiffness, and ST-segment depression, resulting in increased death rates for CVD. DNA-methylation changes have been found to be involved in inflammation, endothelial function, and atherosclerosis. Initial observations in experimental models and humans have shown that air particles and metals, which are constituents of particulate pollution, alter DNA methylation status. Whether the increased risk of CVD observed in subjects exposed to air particles and toxic metals (such as arsenic, cadmium and lead) is mediated by alterations of DNA-methylation patterns is unresolved. The goal of this proposal is to determine whether exposure to air particles and toxic metals (arsenic, cadmium and lead) increases CVD risk by altering global and/or gene specific methylation in elderly subjects over time. Specifically, this proposal will evaluate: 1) the association of the exposure with global DNA methylation in Alu and LINE-1 sequences, and with hypermethylation or hypomethylation in specific genes (ICAM-1, IFN-gamma, p16) involved endothelial function and atherosclerosis; and 2) the association between the above global and gene specific DNA-methylation changes and CVD-related outcomes (Heart-rate variability, Pulse Doppler measurements of atherosclerosis, ST segment elevation/depression, biological markers of inflammation/endothelial function). As a secondary aim, this initiative will explore whether: 1) global or gene-specific methylation status modifies the association of air particles and toxic metals (Pb, As, Cd) with CVD-related endpoints; and 2) the association between exposure and methylation status is modified by plasma levels or intakes of dietary factors (folate, Vitamin B6 & B12), plasma homocysteine levels, and SNPs in DNA methylation genes (MTHFR, cSHMT). The study design, based on an existing cohort of 700 elderly subjects in Eastern Massachusetts, will allow for baseline and longitudinal analysis of air particles, metal biomarkers, DNA methylation patterns and CVD phenotypes, therefore all hypotheses will be tested cross-sectionally and longitudinally. Quantitative DNA methylation analysis, based on PCR amplification and pyrosequencing of bisulphite-treated DNA, will be performed for each study subject on three blood DNA samples collected over a long time span.