INTEGRATIVE GENETIC APPROACHES TO GENE-AIR POLLUTION INTERACTIONS IN ASTHMA

描述(由申请人提供)：虽然在识别与肺功能和哮喘相关的基因和暴露方面取得了进展，但这些病理过程背后的共同易感因素和关键途径还没有得到很好的理解。例如，交通相关污染物对呼吸道高反应性(AHR)、肺发育和哮喘都有不利影响，全基因组关联研究(Gwas)和候选基因方法都发现了与哮喘相关表型相关的基因变异。然而，在识别调节对环境暴露的易感性的基因方面取得的成功有限。我们建议在小鼠和人类中使用一种创新的遗传学方法来识别与交通相关污染物暴露相互作用的新变异，以影响肺功能表型和儿童哮喘的风险。在具体目标1中，我们将从杂交小鼠多样性小组(HMDP)获得约150个近交系和重组近交系小鼠品系的特征，以确定它们对柴油尾气颗粒物(DEP)暴露的反应，DEP是一种与交通相关的模型污染物。肺功能和AHR将使用最先进的体积描记技术进行评估。在初步研究中，我们观察到8个HMDP菌株之间有很大的差异，这很可能是由于这些菌株之间自然发生的遗传差异。在特定的目标2中，我们将使用来自HMDP的表型数据和公开可用的13万个单核苷酸多态的基因型来进行基因-环境(GxE)GWAS，并识别显示与DEP对肺功能有相互作用的证据的基因座。位置上的“暴露反应”候选基因和感兴趣的区域将优先进行功能和生物信息学实验的进一步评估。特殊目标3将建立在小鼠研究的基础上，并使用共线图谱来识别显示GxE相互作用的基因座，这些基因座影响人类哮喘相关的表型。在初步研究中，我们对来自儿童健康研究(CHS)的约4000名受试者进行了交通暴露和哮喘的GWAS和GxE GWAS。利用这些结果和新开发的创新时空暴露模型，我们将使用两阶段设计，并在独立样本中重复，以调查在CHS GxE GWAS中确定的感兴趣基因是否得到HMDP GxE GWAS结果的支持，反之亦然。在具体目标4中，我们将通过体内研究来确认GxE的相互作用。对于人类中两个已验证的易感基因座中的每一个，我们将使用基因数据来召回120名CHS受试者，他们不属于GWAS发现样本的一部分，他们生活在与交通相关的污染暴露水平的高(n=30)和低(n=30)地区，他们是无效等位基因(n=30)的纯合子，并且携带至少一个有效等位基因(n=30)。这些受试者将使用标准的肺活量测定方案进行AHR和肺功能的表型鉴定，并评估临床哮喘状态。这种在小鼠和人类身上的综合基因组学方法的结果将有助于更好地理解基因和环境暴露如何相互作用影响肺功能表型，这可能对哮喘的治疗具有重要的临床、流行病学和翻译意义。

DESCRIPTION (provided by applicant): While progress has been made in identifying the genes and exposures related to lung function and asthma, the common susceptibility factors and critical pathways underlying these pathological processes are not well understood. For example, traffic-related pollutants have adverse effects on airway hyperreactivity (AHR), lung development, and asthma, and both genome-wide association study (GWAS) and candidate gene approaches have identified genetic variants associated with asthma-related phenotypes. However, there has been limited success in identifying genes that modulate susceptibility to environmental exposures. We propose to use an innovative genetics approach in mice and humans to identify novel variants that interact with traffic-related pollutant exposures to affect lung function phenotypes and the risk of childhood asthma. In Specific Aim 1, we will characterize ~150 inbred and recombinant inbred mouse strains from the Hybrid Mouse Diversity Panel (HMDP) to determine their response to diesel exhaust particles (DEP) exposure, a model traffic-related pollutant. Lung function and AHR will be assessed using state-of-the-art plethysmography. In preliminary studies, we observe substantial variability among 8 HMDP strains characterized by this protocol, which is most likely attributable to naturally occurring genetic differences amongst these strains. In Specific Aim 2, we will use the phenotype data from the HMDP and publicly available genotypes of ~130,000 single nucleotide polymorphisms to carry out a gene-environment (GxE) GWAS and identify loci exhibiting evidence for an interaction with DEP on lung function. Positional "exposure-responsive" candidate genes and regions of interest will be prioritized for further evaluation using functional and bioinformatics experiments. Specific Aim 3 will build on the mouse studies and use synteny mapping to identify loci that exhibit GxE interactions to affect asthma-related phenotypes in humans. In preliminary studies, we have carried out a GWAS and a GxE GWAS for traffic exposure and asthma in ~4000 subjects from the Children's Health Study (CHS). Leveraging these results and newly developed and innovative spatial temporal exposure models, we will use a two-stage design, with replication in an independent sample, to investigate whether loci of interest identified in th CHS GxE GWAS are supported by the results of the HMDP GxE GWAS and vice versa. In Specific Aim 4, we will confirm the GxE interactions through in vivo studies. For each of two validated susceptibility loci in humans, we will use genotype data to recall 120 CHS subjects not part of the GWAS discovery sample who live in high (n=30) and low (n=30) areas of traffic-related pollution exposure levels and who are homozygous for the non- effect allele (n=30) and who carry at least one effect allele (n=30). These subjects will be phenotyped for AHR and lung function using standard spirometry protocols and assessed for clinical asthma status. The results of this integrative genomics approach in mice and humans will lead to a better understanding of how genes and environmental exposures interact to affect lung function phenotypes, which could have important clinical, epidemiological, and translational implications for the treatment of asthma.