Particulate matter-induced changes in DNA methylome and transcriptome

 描述(申请人提供)：颗粒物(PM)空气污染是一个全球性的环境健康问题，每年导致370万人过早死亡，占全球所有死亡人数的6.7%。这些死亡很大程度上是由于急性心肺疾病增加所致。虽然降低PM水平的努力降低了PM引起的发病率和死亡率，但PM与心肺疾病之间的关联仍然存在。有必要及早识别有PM所致心肺疾病风险的个人，以进一步减轻疾病负担。暴露于PM与DNA的表观遗传修饰有关，如DNA甲基化(5mC)和羟甲基化(5hmC)，它们调节基因转录。对这些表观遗传学改变的评估可能有助于确定PM诱发心肺疾病的风险个体。越来越多的研究表明PM诱导了表观遗传学变化，但这些发现的意义是有限的，因为这些研究侧重于重复元件的甲基化模式，而没有对整个基因组进行详细的分析。此外，这些研究是在血液白细胞和鼻腔上皮细胞等代理细胞中进行的，在目标组织中没有任何相关性。目前尚不清楚外周血单核细胞中DNA甲基化或羟甲基化的变化是否也存在于靶组织或细胞中，如肺上皮细胞、肺泡巨噬细胞或主动脉内皮细胞。在初步研究中，我们发现PM治疗引起鼻腔和肺上皮细胞和肺泡巨噬细胞5mC减少和5hmC增加的表观遗传学变化。除了表观遗传学变化外，PM在体外培养的原代人鼻和肺上皮细胞和体内暴露于PM的小鼠模型中诱导了一些基因的相似表达和其他基因的差异表达。PM诱导的原代人鼻上皮细胞基因表达和DNA甲基化的改变在个体之间以及男女之间存在差异，这表明宿主相关因素如遗传、年龄和性别在影响PM诱导的反应中起着重要作用。根据我们的初步数据，我们假设DNA甲基化和羟甲基化的变化以及代理细胞(鼻腔上皮细胞和外周血单核细胞)中的基因表达(RNA-seq)可以用来预测靶组织(肺上皮细胞、巨噬细胞、心脏和主动脉)的这些变化。使用临床上相关的PM吸入暴露的小鼠模型，在目标1中，我们将确定PM诱导的DNA甲基组和转录组在代理细胞(鼻黏膜上皮和外周血单核细胞)和目标细胞(肺泡上皮细胞、巨噬细胞、心脏和主动脉)中的不同之处。在目标2中，我们将确定宿主相关因素(品系、性别和年龄)是否影响PM诱导的代理细胞和靶细胞中DNA甲基组和转录组的变化；在目标3中，我们将确定PM诱导的代理细胞和靶细胞中DNA甲基组和转录组的变化是否持续整个生命周期。

 DESCRIPTION (provided by applicant): Particulate matter (PM) air pollution is a global environmental health problem that causes 3.7 million premature deaths annually, representing 6.7% of all deaths worldwide. These deaths are largely due to increased acute cardiopulmonary disease. Although efforts to abate PM levels led to reduction in PM-induced morbidity and mortality, the association between PM and cardiopulmonary disease still persists. There is need for early identification of individuals who are at risk for PM-induced cardiopulmonary disease to reduce the burden of disease further. Exposure to PM is associated with epigenetic modifications of DNA such as DNA methylation (5mC) and hydroxymethylation (5hmC) that regulate gene transcription. Assessment of these epigenetic changes may help with the identification of individuals at risk for development of PM-induced cardiopulmonary diseases. Increasing number of studies demonstrate that PM induces epigenetic changes but the implications of these findings are limited because these studies focused on the methylation patterns of the repetitive elements without detailed analysis of the whole genome. Furthermore, the studies were done in surrogate cells such as blood leukocytes and nasal epithelial cells without any correlation in target tissues. It is not known whether changes in DNA methylation or hydroxymethylation in peripheral blood monocytes can also be found in the target tissue or cell such as lung epithelial cells, alveolar macrophages or aortic endothelial cells. In preliminary studies, we found that PM treatment caused epigenetic changes characterized by reduction in 5mC and increased 5hmC in nasal and lung epithelial cells and alveolar macrophages. In addition to epigenetic changes, PM induced similar expression of some genes and differential expression of others in primary human nasal and lung epithelial cells ex vivo and in a murine model of PM exposure in vivo. PM-induced changes in gene expression and DNA methylation in primary human nasal epithelial cells were different among individuals as well as between males and females suggesting an important role for host-related factors such as genetics, age and sex in influencing the PM-induced responses. Based on our preliminary data, we hypothesized that changes in DNA methylation and hydroxymethylation and the gene expression (RNA-seq) in surrogate cells (nasal epithelial cells and peripheral blood mononuclear cells) can be used to predict those changes in target tissues (lung epithelial cells, and macrophages, heart and aorta). Using a clinically relevant murine model of PM exposure via inhalation, in Aim 1, we will determine the how PM-induced changes in DNA methylome and transcriptome differ in surrogate (nasal epithelium, and peripheral blood monocytes) and target cells (alveolar epithelial cells, macrophages, heart and aorta). In Aim 2, we will determine whether the host related factors (strain, sex and age) affect PM-induced changes in DNA methylome and transcriptome in surrogate and target cells and in Aim 3, we will determine whether the PM-induced changes in DNA methylome and transcriptome in surrogate and target cells persist throughout the lifespan.