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，但对这些病理过程的常见易感因素和关键途径还不清楚。例如，交通相关污染物对气道高反应性（AHR）、肺发育和哮喘有不良影响，全基因组关联研究（GWAS）和候选基因方法都已确定了与哮喘相关表型相关的遗传变异。然而，在确定调节环境暴露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体，以影响肺功能表型和儿童哮喘的风险。在具体目标1中，我们将对来自杂交小鼠多样性小组（HMDP）的约150种近交系和重组近交系小鼠品系进行表征，以确定它们对柴油机排气颗粒（DEP）暴露（一种模型交通相关污染物）的反应。将使用最先进的体积描记法评估肺功能和AHR。在初步研究中，我们观察到该方案表征的8种HMDP菌株之间的显著变异性，这很可能归因于这些菌株之间天然存在的遗传差异。在特定目标2中，我们将使用来自HMDP的表型数据和公开的约130，000个单核苷酸多态性的基因型来进行基因-环境（GxE）GWAS，并鉴定显示与DEP对肺功能相互作用的证据的基因座。将优先考虑位置“确定响应”候选基因和感兴趣区域，以便使用功能和生物信息学实验进行进一步评价。具体目标3将建立在小鼠研究的基础上，并使用同线性作图来鉴定表现出GxE相互作用的基因座，以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，在独立样本中重复，以研究CHS GxE GWAS中确定的目标基因座是否得到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确认GxE相互作用。对于人类中两个经过验证的易感基因座中的每一个，我们将使用基因型数据召回120名不属于GWAS发现样本的CHS受试者，他们生活在交通相关污染暴露水平高（n=30）和低（n=30）的地区，并且是非效应等位基因的纯合型（n=30）并且携带至少一个效应等位基因（n=30）。将使用标准肺量测定方案对这些受试者进行AHR和肺功能表型分析，并评估临床哮喘状态。在小鼠和人类中的这种整合基因组学方法的结果将导致更好地理解基因和环境暴露如何相互作用以影响肺功能表型，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.