CIGARETTE SMOKE IMPACTS FETAL LUNG DNA METHYLATION AND GENE EXPRESSION

描述(申请人提供)：产前吸烟是导致婴儿发病率和死亡率的最常见的可预防原因之一；在美国，估计约有13.8%的妇女在怀孕期间吸烟。宫内烟雾暴露与围产期发病率和儿童后期复杂疾病的发生有关。此外，IUS暴露与胎儿肺发育的改变以及随之而来的肺功能下降、早发性喘息和儿童哮喘有关。DNA甲基化是一种在不影响DNA序列的情况下导致基因表达改变的表观遗传学改变。在成年人中，吸烟与DNA甲基化的变化有关，DNA甲基化影响成人发病的肺部疾病，如COPD和肺癌。在母胎系统中，胎盘基因的表达是引导子宫发育的关键因素。包括尼古丁在内的环境暴露已被证明可以穿过胎盘屏障，影响胎盘基因的表达。除了是化合物的来源，母亲吸烟还影响胎盘缺氧；胎盘缺氧与DNA甲基化和表观遗传过程固有的基因上调有关。该项目的主要目标是证明IUS暴露导致胎盘和发育中胎儿的表观遗传学变化，这些变化对正常人类肺发育至关重要的基因的表达产生下游影响。这项应用特别寻求确定正常早期胎肺发育的DNA甲基化特征，它与正常基因表达的相关性，它与发育中胎盘DNA甲基化的关系，以及这些变化如何通过IUS改变。为了探索我们的全球假说，我们将：(1)检测48个IUS未暴露和48个IUS暴露的胎肺样本DNA表观基因组中超过450,000个CpG位点的DNA甲基化状态，以确定在肺发育的假腺体和导管阶段至关重要的甲基化模式，并在IUS暴露的环境中改变；(2)使用从获得肺样本的相同胎儿的胎盘组织来确定48个IUS暴露和48个IUS暴露的胎盘的表观基因组和基因组图谱。我们随后将比较胎盘内以及胎盘和发育中的肺之间的这些曲线。发育中肺的表观基因组和基因组图谱的相关性将为胎儿IUS暴露的表观基因组学提供直接的功能联系，并为未来侧重于这些变化与呼吸道疾病或其他IUS相关儿童疾病的发展的相关性的工作奠定基础。此外，如果意义重大，通过采集胎盘组织作为其他胎儿器官的标志，胎盘/胎儿肺表观基因组学相关性对新生儿学领域以及将早期胎儿编程与复杂人类疾病的发展联系起来的努力具有直接的翻译意义。 公共卫生相关性：该项目寻求确定与正常和宫内烟雾暴露的肺发育相关的DNA甲基化标记，以及与这些时间段的基因表达特征相关的DNA甲基化标记。通过证明这些标记也与基因表达相关，可以推断这些标记在发育中的胎儿中与吸烟相关的变化中具有功能作用。这最终可能被用于制定新的产前治疗和预防策略。由于宫内吸烟暴露仍然是围产期发病率和死亡率的主要原因，也是发展包括哮喘在内的复杂儿童疾病的主要风险因素，这些战略有可能大幅降低与产前吸烟有关的发病率和经济负担。

DESCRIPTION (provided by applicant): Prenatal smoking is one of the most common preventable causes of infant morbidity and mortality; in the United States, it is estimated that about 13.8% of women smoke during pregnancy. In utero smoke (IUS) exposure has been associated with both perinatal morbidity and the development of complex diseases in later childhood. Additionally, IUS exposure has been associated with alterations in fetal lung development and consequent decreased pulmonary function, early-onset wheeze, and asthma in childhood. DNA methylation is one type of epigenetic change that results in the alteration of gene expression without affecting DNA sequence. In adults, cigarette smoking has been associated with alterations in DNA methylation, which influences the development of adult onset lung diseases such as COPD and lung cancer. In the maternal-fetal system, placental gene expression is a critical element for guiding in utero development. Environmental exposures including nicotine have been demonstrated to cross the placental barrier and impact placental gene expression. In addition to being a source of compounds, maternal cigarette smoking impacts placental hypoxia; placental hypoxia has been associated with up-regulation of genes intrinsic to DNA methylation and epigenetic processes. The major goal of this project is to demonstrate that IUS exposure results in epigenetic changes in the placenta and developing fetus that have downstream impact on the expression of genes crucial to normal human lung development. This application specifically seeks to define the DNA methylation profile of normal early fetal lung development, its correlation with normal gene expression, its relationship to DNA methylation in the developing placenta, and how each of these is altered via IUS. To explore our global hypothesis we will: (1) examine DNA methylation status of greater than 450,000 CpG sites across the epigenome in DNA from 48 IUS-unexposed and 48 IUS-exposed fetal lung samples to identify methylation patterns critical during to the pseudoglandular and canalicular stages of lung development and altered in the setting of IUS exposure; and (2) use placental tissue from the same fetuses from which the lung samples are obtained to identify the epigenomic and genomic profiles of 48 IUS-exposed and 48 IUS-unexposed placentas. We will subsequently compare these profiles within placenta and between placenta and the developing lung. The correlation of epigenomic and genomic profiles within the developing lung will provide a direct functional link to the epigenomics of fetal IUS exposure and set the stage for future work focused on the relevance of these changes to the development of airways disease or other IUS-associated childhood diseases. Moreover, if significant, by sampling placental tissue as a marker of other fetal organs, the placental/fetal lung epigenomic correlation has direct translational implications for the field of neonatology, and efforts to link early-life fetal programming to the development of complex human disease. PUBLIC HEALTH RELEVANCE: This project seeks to identify DNA methylation marks associated with normal and in utero smoke-exposed lung development and with the genetic expression signature during those times. By demonstrating that these marks also correlate with gene expression, the marks can be inferred to have a functional role in smoking-related changes in the developing fetus. This may eventually be used to formulate novel prenatal therapeutic and preventative strategies. Since in utero smoke exposure remains a leading cause of perinatal morbidity and mortality and a major risk factor for the development of complex childhood disease, including asthma, these strategies have the potential to substantially decrease the morbidity and financial burden related to prenatal smoking.