The Genetic and Biological Determinants of Environmental Airway Disease

肺内先天免疫和获得性免疫之间的相互作用是肺部疾病发展的核心，包括哮喘和闭塞性毛细支气管炎，这种情况发生在肺移植排斥反应中。该研究计划的总体目标是在环境呼吸道疾病的小鼠模型和人类群体中识别介导宿主对一些环境毒素和过敏原的反应的基因。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。 在一个人类哮喘项目中，我们的目标是确定与哮喘患者的气流阻塞和呼吸道炎症发展有关的基因，并确定这些差异表达基因的多态是否容易使个人患上哮喘。我们假设哮喘患者在特定的亚段气道挑战后，呼吸道细胞表达的基因的多态倾向于个体发生哮喘。为了验证这一假说，我们已经确定了在用刺激诱导获得性(屋尘螨)或先天(LPS)免疫反应的特定亚段呼吸道刺激后，呼吸道上皮细胞差异表达的基因，然后将确定这些基因的多态是否与哮喘的发生有关，在一个单独的、特征良好的哮喘患者家族队列中。 在另一项研究中，我们正在使用环境呼吸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对细菌毒素的先天免疫系统的影响。肺部经常暴露在广泛的环境毒素和过敏原中，但这些环境暴露对宿主先天免疫系统的影响尚不清楚。我们还建立了一种慢性脂多糖暴露的小鼠模型，其特征是呼吸道炎症、持续的气道高反应性和伴随上皮下间隙增厚的气道重塑。调节这一过程并最终导致气道重塑的具体细胞相互作用仍有待阐明。 越来越多的证据表明，除了遗传因素外，其他因素也有助于哮喘的发生。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。为了实现这一目标，我们正在研究表观遗传学在哮喘发病中的作用。我们已经建立了一种基于序列的技术，即甲基化特异性数字染色体配对(MSDK)，以识别小鼠基因组中的差异甲基化基因座。 最后，我们在移植生物学的背景下研究先天免疫和获得性免疫之间的相互作用。慢性排斥反应表现为呼吸道纤维化限制了人肺移植后的长期存活。虽然排斥反应被认为是受者对同种异体肺组织的适应性免疫反应的结果，但同种异体肺移植也暴露于以吸入毒素、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多名肺移植受者和他们各自的捐赠者身上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反应小鼠移植模型，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.