Association between ANP and NPRA Gene Polymorphisms and Severity of Atopy and Ast

描述（由申请人提供）：本提案旨在研究心房利钠肽（ANP）及其受体NPRA作为哮喘的候选基因，哮喘是一种常见的慢性炎症性肺部疾病，每年约有4000人死于哮喘。哮喘的复杂性反映在大量的遗传因素上，这些遗传因素可以构成特定的哮喘表型。导致哮喘的基因被认为是影响但不决定整体疾病风险的易感位点。决定整体疾病风险的基因尚未被确定，这似乎是合理的。ANP是前ANP的c端肽，在胚胎和新生小鼠胸腺细胞的发育中起关键作用，并促进成年小鼠肺部的T辅助型2 （Th2）显性反应，因此可能参与哮喘的发生和发展。缺乏NPRA的小鼠不患哮喘。ANP-NPRA通路参与指导人类dc促进th2优势和人类肥大细胞以ige依赖性和非依赖性方式释放介质。对488例哮喘患者和186例非哮喘健康对照者的4个NPPA基因snp进行了初步关联分析，结果显示非裔美国人和白种人的共同单倍型（CGTG）与哮喘存在显著关联。这些发现导致假设NPPA和NPR1是哮喘的重要易感位点，并且存在与不同的特应性（如血清总IgE）和哮喘（如支气管高反应性）表型相关的特定多态性。本次提交的主要目的是确定ANP、NPPA和NPRA受体基因NPR1的基因多态性是否与哮喘相关。我们假设NPPA和NPR1是哮喘的重要易感位点，并且存在与不同的特应性（如血清总IgE）和哮喘（如支气管高反应性）表型相关的特定多态性。为了验证这一假设，提出了以下具体目标。在Aim #1中，计划确定哮喘患者和非裔美国人和白种人人群中ANP （NPPA）和NPRA （NPR1）基因型和单倍型snp （htSNP）之间的关系。714名哮喘患者和500名年龄、种族、BMI和性别匹配的对照组的单倍型之间的关联将使用从美国肺脏协会哮喘临床研究中心（ALA-ACRC）的几项临床试验中收集的DNA进行检查。此外，htSNP方法将用于捕获关联分析中的遗传变异性。在Aim #2中，建议研究pro-ANP （I-98）是否可以作为哮喘和/或特应性的生物标志物。计划使用通过ALA-ACRC哮喘研究收集的具有明确特征的过敏/哮喘受试者亚组（n = 714例和500例对照）的血清样本。因此，血清前anp水平将通过既定的EIA来测量，并与aim#1中研究的基因型和单倍型snp与这些患者的疾病严重程度以及相同血清样本中估计的总IgE相关。这些结果将提示ANP是否可以作为哮喘的生物标志物。对这一新的哮喘候选基因多态性的分析有望增加我们对NPPA和NPR1基因的认识，这两个基因在包括哮喘在内的几种常见人类疾病中起着关键作用。

DESCRIPTION (provided by applicant): This proposal aims to investigate the atrial natriuretic peptide (ANP) and its receptor, NPRA, as candidate genes for asthma, a common chronic inflammatory lung disease to which about 4000 individuals succumb each year in this country. The complexity of asthma is reflected in the large number of genetic factors that can make up a specific asthma phenotype. The genes contributing to asthma are thought to be susceptibility loci that influence, but do not determine, the overall disease risk. It is plausible that genes that determine the overall disease risk are yet to be identified. ANP, the C-terminal peptide of pro-ANP, plays a pivotal role in the development of thymocytes in embryonic and neonatal mice and promotes a T helper type 2 (Th2)-dominant response in the lungs of adult mice and therefore may contribute to the genesis and progression of asthma. NPRA deficient mice are protected from asthma. The ANP-NPRA pathway is involved in directing human DCs to promote Th2-dominance and human mast cells to release mediators in both an IgE-dependent and - independent manner. A preliminary association analysis of 4 SNPs of NPPA gene were typed in 488 patients with well-characterized asthma (cases) and in 186 healthy controls without asthma shows that there is a significant associations for asthma between a common haplotype (CGTG) in both African Americans and Caucasians. These findings have led to the hypothesis that NPPA and NPR1 are important susceptibility loci for asthma and that there are specific polymorphisms associated with different atopy (e.g., total serum IgE) and asthma (e.g., bronchial hyperreactivity) phenotypes. The primary goal of this submission is to determine if polymorphisms in the gene for ANP, NPPA, and the NPRA receptor gene, NPR1, are associated with asthma. We hypothesize that NPPA and NPR1 are important susceptibility loci for asthma and that there are specific polymorphisms associated with different atopy (e.g. total serum IgE) and asthma (e.g., bronchial hyperreactivity) phenotypes. To test this hypothesis, the following specific aims are proposed. In Aim #1, it is planned to determine the association between genotype and haplotype SNPs (htSNP) in ANP (NPPA) and NPRA (NPR1) genes in asthmatics and matched healthy controls in a population of African-Americans and Caucasians. The associations among haplotypes in 714 subjects with asthma and 500 controls matched for age, ethnicity, BMI and gender will be examined using DNA collected from several clinical trials from the American Lung Association, Asthma Clinical Research Centers (ALA-ACRC). Additionally, the htSNP approach will be used to capture genetic variability in association analyses. In Aim #2, it is proposed to investigate whether pro-ANP (I-98) can be biomarker of asthma and/or atopy. It is planned to use serum samples from a subgroup of well-characterized allergic/asthmatic subjects (n = 714 cases and 500 controls), collected through ALA-ACRC asthma studies. Thus, serum levels of pro-ANP will be measured by an established EIA and correlated with genotype and haplotype SNPs studied in aim#1 with disease severity of these patients and with total IgE estimated in the same serum samples. These results will indicate whether ANP can be biomarker for asthma. The analysis of polymorphism in this novel candidate gene for asthma is expected to increase our knowledge of NPPA and NPR1 genes which play a critical role in several common human diseases including asthma. PUBLIC HEALTH RELEVANCE: The incidence of asthma and the rates of hospitalization, health care utilization and mortality because of asthma are increasing worldwide. Although better management has decreased asthma mortality in this country, about 4000 individuals will die each year from asthma. Asthma is the most common disease of childhood. African American children and young adults are three to four times more likely than whites to be hospitalized for asthma and four to six times more likely to die from asthma. Asthma is a complex disease and this complexity is reflected in the large number of genetic factors that can make up a specific asthma phenotype. This proposal aims to investigate the association of polymorphism of a positional candidate gene, ANP and its receptor, which appear to play a critical role in pathogenesis of many inflammatory lung diseases including asthma and chronic obstructive pulmonary diseases. The existing results indicate that inhibiting this pathway might be therapeutic for asthmatics. Establishing an association of ANP polymorphisms will not only confirm the importance of this gene in asthma, but may also indicate who will benefit from an ANP-based therapy.