Gene-environment Interaction And Pulmonary Disease: Tran

遗传背景和氧化环境刺激在人类肺部疾病发病机制中的相互作用在很大程度上尚未被探索。氧化应激的生物反应是许多炎症性疾病的关键机制。在这个新项目中，我们已经开始了三项研究计划，这些计划是从我们的炎症和急性肺损伤小鼠模型演变而来的。在第一个项目中，我们与dr。Francine Kauffmann和Rachel Nadif （INSERM, Paris）研究了暴露于不同环境氧化剂、煤尘和香烟烟雾的个体对煤炭工人尘肺病（CWP）易感性的遗传基础。Drs。Kauffmann和Nadif对253名煤矿工人进行了一项前瞻性流行病学研究，其中包括对可能涉及CWP（一种炎症性肺病）的环境刺激反应的定量表型。研究了6种氧化应激标志物作为暴露反应的中间表型，包括红细胞谷胱甘肽过氧化物酶（GSH-Px）和过氧化氢酶活性。研究的氧化剂暴露是吸烟习惯和累积粉尘暴露，通过工作史和环境暴露测量来评估。疾病表型包括第一次调查时的亚临床计算机断层扫描评分和间隔5年两次的x线浸润评分，以评估已建立的CWP。我的实验室采集了参与研究的每个人的血液并分离了DNA。我们开始研究CWP易感性的遗传基础，通过评估选定的表型与以下基因类别的多态性的关联：先天免疫、炎症和抗氧化。对矿工进行了肿瘤坏死因子a （TNF）和淋巴毒素a （LTA）基因的常见功能多态性基因分型，这两种促炎细胞因子与慢性肺病的发病机制有关。我们还对受试者进行了过氧化氢酶（CAT）多态性分型。关于中间表型的基因-环境相互作用，我们的研究结果显示TNF中-308启动子多态性与职业暴露对红细胞GSH-Px活性的相互作用，在高暴露者中具有显著相关性，而在低暴露者中没有观察到相关性。关于基因-中间表型相互作用对临床结果的影响，我们的研究结果显示，在过氧化氢酶活性低的患者中，CWP患病率与LTA中NcoI多态性相关，而在过氧化氢酶活性高（先验保护）的患者中没有观察到相关。我们还发现CAT与血液过氧化氢酶活性和疾病结局有显著关联。结果表明，遗传背景与环境暴露和中间反应表型的相互作用是煤矿工人疾病发病机制的重要组成部分。

Interaction between genetic background and oxidative environmental stimuli in the pathogenesis of human lung disease has been largely unexplored. Biological response to oxidative stress is a key mechanism in numerous inflammatory diseases. In this new program, we have begun three research initiatives that evolved from our mouse modeling of inflammation and acute lung injury. In the first project, we have extablished strong collaboration with Drs. Francine Kauffmann and Rachel Nadif (INSERM, Paris) to investigate the genetic basis of susceptibility to coal workers pneumoconiosis (CWP) in individuals differentially exposed to environmental oxidants coal dust and cigarette smoke. Drs. Kauffmann and Nadif have undertaken a prospective epidemiologic study in 253 coal miners, which included quantitative phenotypes of response to environmental stimuli that may be involved in CWP, an inflammatory lung disease. Six oxidative stress markers were studied as intermediate phenotypes of response to exposure, including erythrocyte glutathione peroxidase (GSH-Px) and catalase activities. Oxidant exposures studied were smoking habits and cumulative dust exposure assessed by job history and ambient measures of exposure. Disease phenotypes included subclinical computed tomography score at the first survey and X-ray profusion grades twice 5 years apart to assess established CWP. My laboratory obtained blood from each of the individuals recruited to the study and DNA was isolated. We began to investigate the genetic basis for CWP susceptibility by evaluating association of selected phenotypes with polymorphisms in the following classes or categories of genes: innate immunity, inflammation, and antioxidant. Miners were genotyped for common functional polymorphisms in the gene for tumor necrosis factor a (TNF) and lymphotoxin a (LTA), two proinflammatory cytokines that have been implicated in the pathogenesis of chronic lung disease. We have also typed the subjects for catalase (CAT)polymorphisms. Regarding gene-environment interaction on intermediate phenotypes, our results showed interaction of the -308 promoter polymorphism in TNF with occupational exposure on erythrocyte GSH-Px activity with a significant association in those with high exposure whereas no association was observed among those with low exposure. Regarding gene-intermediate phenotype interaction on clinical outcome, our results showed an association of CWP prevalence with the NcoI polymorphism in LTA in those with low catalase activity whereas no association was observed in those with high (a priori protective) activity. We have also found significant association of CAT with blood catalase activity and disease outcome. Results suggest that interactions of genetic background with environmental exposure and intermediate response phenotypes are important components in the pathogenesis of disease (CWP) in coal miners. A second project is currently being established to investigate the genetic basis of susceptibility to adverse outcomes of acute respiratory distress syndrome (ARDS). ARDS is a major acute lung disease in adults and neonates, and is characterized by noncardiogenic edema and inflammation. The mortality rate for ARDS ranges from 50-80%. The incidence of ARDS is not well established, but approximately 2-8 cases per 100,000 are estimated. The mechanisms of susceptibility are unclear, and there are no specific therapies. Our studies in inbred mice have identified the transcription factor NRF2 as a candidate gene for susceptibility to hyperoxic lung injury, a model of ARDS. We have hypothesized, therefore, that loss-of-function polymorphisms in NRF2 predispose to oxidative lung damage associated with ALI/ARDS. To date, the genomic sequence of NRF2 is not well characterized and only a few SNPs have been localized to coding regions within the gene. In the current study, portions of the coding region and 1-kb of the promoter were amplified, sequenced and compared in order to locate NRF2polymorphisms, and to determine whether any identified SNPs have functional relevance to NRF2 activity. We are also evaluating each SNP by association with disease pathogenesis in a population of ALI patients through a collaboration with Dr. Jason Christie (University of Pennsylvania). Our third project is designed to evaluate genetic mechanisms of host response to respiratory syncytial virus and innate immunity studies in mice and humans. This project is designed to investigate the role of toll-like receptors in respiratory syncytial virus (RSV) infection and disease progression. Because TLR4 appears to be critical to protection against RSV immune challenge, a collaboration has been established with Dr. Fernando Polack (Johns Hopkins University) to test the hypothesis that loss of TLR4 function will enhance development of lower respiratory tract infection during primary RSV infection in infants.