The Genetic and Biological Determinants of Environmental Airway Disease

肺中先天免疫和适应性免疫之间的相互作用是肺部疾病（包括哮喘和闭塞性细支气管炎，一种伴随肺移植排斥反应发生的疾病）发展的核心。 这项研究计划的总体目标是在环境气道疾病的小鼠模型和人群中鉴定介导宿主对一些环境毒素和过敏原反应的基因。 具体的环境挑战包括脂多糖（LPS）、过敏原（屋尘螨和卵清蛋白）、臭氧和颗粒物。 在人类哮喘项目中，我们的目标是鉴定参与哮喘患者气流阻塞和气道炎症发展的基因，并确定这些差异表达基因的多态性是否使个体易患哮喘。 我们假设，在特定亚段气道挑战后，哮喘患者气道细胞表达的基因多态性使个体易患哮喘。 为了验证这一假设，我们已经确定了差异表达的基因，细胞在气道上皮细胞后，特定的亚段气道挑战与刺激，诱导获得性（屋尘螨）或先天性（LPS）免疫反应，然后将确定这些基因的多态性是否与哮喘的发展在一个单独的，充分表征，家族性哮喘患者队列。 在另一系列研究中，我们正在使用环境气道疾病的小鼠模型来研究预先暴露于特定环境毒素和过敏原对宿主先天免疫系统对细菌毒素的影响。 肺经常暴露于广泛的环境毒素和过敏原，但这些环境暴露对宿主先天免疫系统的影响尚不清楚。 我们还开发了一种慢性LPS暴露的小鼠模型，其特征在于气道炎症、持续气道高反应性和气道重塑伴上皮下空间增厚。 调节这一过程并最终导致气道重塑的特定细胞相互作用仍有待阐明。 越来越多的证据表明，除了遗传因素之外，其他因素也会导致哮喘的发生。例如，饮食和维生素补充，特别是在怀孕期间，是一个潜在的重要因素。 为了追求这一点，我们正在研究表观遗传学在哮喘发展中的作用。 我们已经建立了一个基于序列的技术，即甲基化特异性数字核型分析（MSDK），以确定小鼠基因组中的差异甲基化位点。 最后，我们正在研究移植生物学背景下先天免疫和适应性免疫之间的相互作用。 慢性排斥反应表现为气道纤维化，限制了人肺移植后的长期生存。 尽管排斥被认为是由于受体对同种异体肺组织的适应性免疫应答而发生的，但肺同种异体移植物也暴露于吸入毒素、感染和其他环境刺激形式的显著先天免疫刺激。 我们的假设是先天免疫激活促进了肺移植急性和慢性排斥反应的发生。 为了验证这一假设，我们从200多名肺移植受者及其各自的供体中分离了遗传物质和组织样本，并描述了他们在移植排斥反应方面的临床结果。 我们还试图开发一种新的基于免疫学的慢性肺排斥小鼠移植模型，以进一步验证我们的假设。

The interplay between innate and adaptive immunity in the lung is central to the development of lung disease including asthma and obliterative bronchiolitis, a condition that occurs with lung transplant rejection. The overall goal of this research program is to identify genes that mediate the host response to a number of environmental toxins and allergens both in mouse models of environmental airway diseases and in human populations. Specific environmental challenges include lipopolysacharide (LPS), allergens (house dust mite and ovalbumin), ozone, and particulate matter. In a human asthma project, our goal is to identify genes that are involved in the development of airflow obstruction and airway inflammation in asthmatics, and to determine whether polymorphisms in these differentially expressed genes predispose individuals to develop asthma. We hypothesize that polymorphisms of genes expressed by airway cells in asthmatics following specific subsegmental airway challenges predispose individuals to the development of asthma. To test this hypothesis, we have identified genes that are differentially expressed by cells in the airway epithelia following specific subsegmental airway challenge with stimuli that induce acquired (house dust mite) or innate (LPS) immune responses, and will then determine whether polymorphisms in these genes are associated with the development of asthma in a separate, well characterized, familial cohort of asthmatics. In another line of investigations, we are using mouse models of environmental airway disease to study the effect of pre-exposure to specific environmental toxins and allergens on the host innate immune system to bacterial toxins. The lung is constantly exposed to a broad spectrum of environmental toxins and allergens but the effect that these environmental exposures have on the host innate immune system is not well understood. We have also developed a mouse model of chronic LPS exposure that is characterized by airway inflammation, persistent airway hyper-reactivity, and airway remodeling with thickening of the subepithelial space. The specific cellular interactions that regulate this process and ultimately lead to airways remodeling remain to be elucidated. There is an increasing amount of evidence suggesting that other factors besides genetics contributes to the development of asthma. For instance, diet and vitamin supplementation, especially during pregnancy, is a potentially important factor. To pursue this, we are examining the role of epigenetics in the development of asthma. We have established a sequence based technique, namely Methylation Specific Digital Karyotaping (MSDK), to identify differentially methylated loci in the mouse genome. Finally, we are examining the interplay between innate and adaptive immunity in the context of transplant biology. Chronic rejection manifest as airway fibrosis limit longterm survival after human lung transplant. Although rejection is thought to occur as a result of the recipient adaptive immune response to the allogenic lung tissue, the lung allograft is also exposed to significant innate immune stimuli in the form of inhalational toxins, infections, and other environmental stimuli. Our hypothesis in this line of investigation is that innate immune activation promotes the development of acute and chronic lung allograft rejection. In order to test this hypothesis we have isolated genetic material and tissue samples from over 200 lung transplant recipients and their respective donors and characterized their clinical outcomes with regards to graft rejection. We have also sought to develop a novel immunologically based murine transplant model of chronic lung rejection to pursue further testing of our hypothesis.