Genetics of Smoke-Altered LTA4H in COPD

COPD 中烟雾改变的 LTA4H 的遗传学

• 批准号: 9502350
• 负责人: J Edwin Blalock
• 金额: $ 39.04万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-15 至 2020-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9502350
• 关键词: Acrolein; Affect; American; Aminopeptidase; Anti-inflammatory; Automobile Driving; Azithromycin; Biological; Biological Markers; Catalytic Domain; Cause of Death; Cells; Chemicals; Chemotactic Factors; Chronic; Chronic Disease; Chronic Obstructive Airway Disease; Chronic lung disease; Code; Collagen; Critical Care; Disease; Disease Progression; Environment; Enzymes; Frequencies; Generations; Genes; Genetic; Genetic Polymorphism; Genetic Variation; Genome; Genotype; Glycine; Heritability; Human; Hydrolase; In Vitro; Individual; Inflammation; Inflammatory; Inflammatory Response; Journals; Laboratories; Leukotriene A4; Leukotriene B4; Lung diseases; Macrolides; Measures; Medicine; Modeling; Morbidity - disease rate; Paper; Pathology; Pathway interactions; Phenotype; Play; Population; Predisposition; Process; Proline; Promoter Regions; Proteins; Public Health; Publications; Regulation; Reporter; Risk Factors; Role; Science; Site; Smoke; Smoking; System; Testing; Time; Twin Multiple Birth; Variant; airway inflammation; base; cigarette smoke; cohort; disorder risk; enzyme activity; gene environment interaction; genetic analysis; improved; in vivo; insight; leukotriene A4 hydrolase; mortality; programs; promoter; public health relevance; respiratory; response; therapeutic target

 DESCRIPTION (provided by applicant): A key molecule in the pathology of ongoing inflammation in COPD is the collagen fragment proline-glycine- proline (PGP). From the CCRN Macrolide trial, we found that PGP levels markedly declined in concert with azithromycin's ability to reduce COPD exacerbation frequency. To our knowledge, PGP was the only biomarker studied that showed such a profound response. More recently, our laboratory has demonstrated that PGP is negatively regulated by leukotriene A4 hydrolase (LTA4H). LTA4H is a unique enzyme which possesses both a hydrolase and aminopeptidase catalytic site. Although the hydrolase site of LTA4H is well- known to catalyze the conversion of leukotriene A4 into leukotriene B4 (a PMN chemoattractant), the substrate of the aminopeptidase activity was unknown. In a pivotal Science paper in 2010, our group demonstrated that the aminopeptidase activity degrades PGP, thereby leading to less neutrophilic (PMN) inflammation. As such, LTA4H is both pro-inflammatory (hydrolase) and anti-inflammatory (aminopeptidase) at baseline serving as a critical pivot in inflammatory responses. Cigarette smoke can upregulate the total amount of LTA4H as well as chemically modify and inactivate LTA4H's aminopeptidase but not hydrolase activity thus leaving LTB4 generation intact while allowing for chronic accumulation of inflammatory levels of PGP. Therefore, the regulation of this enzyme's amount and activities may have a crucial role in airway inflammation associated with COPD. In fact, we found marked elevation in amount but reduction in LTA4H aminopeptidase activity in smoking and COPD cohorts compared to non-lung disease cohorts although there was notable variability in each of these groups suggesting that the interaction between environment and genetics may play a key feature in COPD disease progression. In fact, previous genetic analyses have revealed a number of polymorphisms in the promoter and coding regions of LTA4H that showed associations with a variety of inflammatory disorders including COPD. In this proposal to assign alterations in LTA4H protein levels and enzyme activity to associated SNPs, we will examine genetic variation in the putative promoter region of LTA4H to determine impact on LTA4H protein levels both in vitro and in vivo. We will also explore the role of SNPs in the coding regio of LTA4H on its activity. The overall hypothesis of this proposal is that variability in expression and enzymatic activity of LTA4H impacts COPD susceptibility and related phenotypes, thus genetic variation affecting LTA4H expression and aminopeptidase function impacts COPD-related phenotypes. Such human studies are only now possible as a result of the COPDGene program, the renewal of which provides a time-sensitive window to conduct these paradigm establishing studies.

 描述（由申请人提供）：COPD持续炎症病理学中的关键分子是胶原蛋白片段脯氨酸-甘氨酸-脯氨酸（PGP）。从CCRN大环内酯试验中，我们发现PGP水平显著下降与阿奇霉素降低COPD急性加重频率的能力一致。据我们所知，PGP是唯一一个显示出如此深刻反应的生物标志物。最近，我们的实验室已经证明，PGP是负调控的白三烯A4水解酶（LTA 4 H）。LTA 4 H是一种独特的酶，它同时具有水解酶和氨肽酶催化位点。虽然LTA 4 H的水解酶位点催化白三烯A4转化为白三烯B4（一种PMN化学引诱物）是众所周知的，但氨肽酶活性的底物是未知的。在2010年的一篇重要的科学论文中，我们的研究小组证明了氨肽酶的活性可以降解PGP，从而减少嗜中性粒细胞（PMN）的炎症。因此，LTA 4 H在基线时既是促炎性的（水解酶）又是抗炎性的（氨肽酶），在炎症反应中起关键作用。香烟烟雾可以上调LTA 4 H的总量，以及化学修饰和抑制LTA 4 H的氨肽酶而不是水解酶活性，从而使LTB 4的产生保持完整，同时允许PGP的炎症水平的慢性积累。因此，这种酶的量和活性的调节可能在与COPD相关的气道炎症中起关键作用。事实上，我们发现，与非肺部疾病队列相比，吸烟和COPD队列中的LTA 4 H氨肽酶活性显著升高，但降低，尽管这些组中的每一组都存在显著的变异性，表明环境和遗传学之间的相互作用可能在COPD疾病进展中发挥关键作用。事实上，先前的遗传分析已经揭示了LTA 4 H启动子和编码区的许多多态性，这些多态性与包括COPD在内的各种炎症性疾病有关。在本提案中，将LTA 4 H蛋白水平和酶活性的改变分配给相关SNP，我们将检查LTA 4 H推定启动子区域的遗传变异，以确定体外和体内对LTA 4 H蛋白水平的影响。我们还将探讨LTA 4 H编码区的SNP对其活性的作用。这一建议的总体假设是， LTA 4 H的酶活性影响COPD易感性和相关表型，因此影响LTA 4 H表达和氨肽酶功能的遗传变异影响COPD相关表型。由于COPDGene计划，这种人类研究现在才有可能，该计划的更新为进行这些范式建立研究提供了一个时间敏感的窗口。