Gene-environment Interaction And Pulmonary Disease: Tran

在人类肺部疾病的发病机制中，遗传背景和氧化环境刺激之间的相互作用在很大程度上尚未探索。对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发展而来的。在第一个项目中，我们与Francine Kauffmann博士和Rachel Nadif博士（巴黎巴黎）建立了密切的合作关系，以调查不同暴露于环境氧化剂煤尘和香烟烟雾的个体对煤工尘肺（CWP）易感性的遗传基础。Kauffmann和Nadif博士对253名煤矿工人进行了一项前瞻性流行病学研究，其中包括对可能与CWP（一种炎症性肺病）有关的环境刺激反应的定量表型。六氧化应激标志物进行了研究，作为中间表型的暴露，包括红细胞谷胱甘肽过氧化物酶（GSH-Px）和过氧化氢酶的活动。氧化剂暴露研究吸烟习惯和累积粉尘暴露评估的工作历史和暴露的环境措施。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线灌注分级，以评估确定的CWP。我的实验室从每一个被招募到研究中的人身上采集了血液，并分离了DNA。我们开始研究CWP易感性的遗传基础，通过评估所选表型与以下类别或类别的基因多态性的关联：先天免疫，炎症和抗氧化剂。对矿工进行了基因分型，以确定肿瘤坏死因子a（TNF）和光敏素a（LTA）基因中常见的功能多态性，这两种促炎细胞因子与慢性肺部疾病的发病机制有关。我们还对受试者的过氧化氢酶（CAT）多态性进行了分型。关于中间表型的基因-环境相互作用，我们的研究结果表明，相互作用的-308启动子多态性的TNF与职业暴露对红细胞GSH-Px活性的显着关联，在那些与高暴露，而没有相关性，在那些与低暴露。关于基因-中间表型相互作用对临床结果的影响，我们的研究结果表明，在过氧化氢酶活性低的患者中，CWP患病率与LTA的NcoI多态性相关，而在过氧化氢酶活性高的患者中未观察到相关性（先验保护性）。我们还发现CAT与血液过氧化氢酶活性和疾病结果显著相关。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（CWP）发病机制的重要组成部分。 目前正在建立第二个项目，以调查急性呼吸窘迫综合征（ARDS）不良后果易感性的遗传基础。急性呼吸窘迫综合征（ARDS）是成人和新生儿的一种主要急性肺部疾病，其特征是非心源性水肿和炎症。ARDS的死亡率为50- 80%。成人呼吸窘迫综合征的发病率尚未完全确定，但估计每100，000人中约有2-8例。易感性的机制尚不清楚，也没有具体的治疗方法。我们在近交系小鼠中的研究已经确定转录因子NRF 2是高氧肺损伤（一种ARDS模型）易感性的候选基因。因此，我们假设NRF 2的功能缺失多态性易导致与ALI/ARDS相关的氧化性肺损伤。到目前为止，NRF 2的基因组序列还没有得到很好的表征，只有少数SNP被定位于基因内的编码区。在本研究中，部分编码区和1-kb的启动子扩增，测序和比较，以定位NRF 2多态性，并确定是否有任何确定的SNPs与NRF 2活性的功能相关。我们还通过与Jason Christie博士（宾夕法尼亚大学）的合作，在ALI患者人群中评估每个SNP与疾病发病机制的相关性。 我们的第三个项目旨在评估宿主对呼吸道合胞病毒的反应的遗传机制以及小鼠和人类的先天免疫研究。本项目旨在研究Toll样受体在呼吸道合胞病毒（RSV）感染和疾病进展中的作用。由于TLR 4似乎对保护免受RSV免疫攻击至关重要，因此与Fernando Polack博士（约翰霍普金斯大学）建立了合作关系，以检验TLR 4功能丧失将增强婴儿原发性RSV感染期间下呼吸道感染发展的假设。

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.