Mechanisms of Initiation and Persistence of Allergic Asthma

描述（由申请人提供）：这项哮喘和过敏性疾病中心拨款申请是为了继续四名UCSF教师之间长期富有成效的合作，他们长期对过敏性气道炎症和哮喘的机制感兴趣。本应用的中心目标是确定过敏性气道炎症和气道高反应性发生和持续的关键机制。该申请包括两个项目，将利用小鼠模型，第三个项目将检查这些模型中确定的分子靶点和途径与人类哮喘患病率、严重程度和药物反应性的相关性。该中心的首席研究员和项目1的负责人Dean Sheppard已经确定了转化生长因子激活的关键作用。（TGF??）被两种不同的整合素(? ？6和？v？8)过敏性哮喘慢性模型的气道高反应性和同源免疫反应的调节。本提案将利用一系列的转基因小鼠品系，直接考察TGF?？在这些影响中，确定负责的关键细胞类型，并确定这些反应的分子机制。项目2是基于项目负责人理查德·洛克斯利（Richard Locksley）最近的数据，几丁质是真菌、寄生虫和甲壳类动物的重要结构成分，可以激活巨噬细胞并启动先天免疫细胞，以启动2型免疫反应。本项目提出的工作将利用一系列新的报告细胞系来研究关键的几丁质反应细胞以及这一途径引发过敏性炎症的机制和相关性。项目3由Esteban Burchard和John Fahy共同领导，将对几丁质降解酶序列变异与TGF??之间的遗传关联进行初步观察。以及过敏性致敏和哮喘，以更深入地探究几丁质酶序列变异和TGF？激活和信号通路，包括项目1中研究的整合素亚基。本项目还将利用哮喘患者和健康对照者的支气管肺泡灌洗液样本和组织来评估相关基因的功能意义。这些项目将由生理学和组织分析核心（将为所有3个项目提供广泛支持）和集中管理核心提供支持。概要：本中心将评估哮喘发生和持续的机制。通过确定新的途径和分子靶点，并测试它们与人类哮喘、哮喘严重程度和药物反应的相关性，该中心的工作应该为开发针对这种常见且往往具有破坏性的疾病的新疗法提供线索。

DESCRIPTION (provided by applicant): This Asthma and Allergic Diseases Center Grant application is an effort to continue a long-standing fruitful collaboration among 4 UCSF faculty members with a long-standing interest in the mechanisms underlying allergic airway inflammation and asthma. The central goals of this application are to determine critical mechanisms underlying the initiation and persistence of allergic airway inflammation and airway hyperresponsiveness. The application includes two projects that will utilize murine models and a third that will examine the relevance of molecular targets and pathways identified in these models to asthma prevalence, severity and drug responsiveness in humans. The Center Principal Investigator and leader of Project 1, Dean Sheppard, has identified critical roles for activation of transforming growth factor ? (TGF??) by two different integrins (?v?6 and ?v?8) in airway hyperresponsiveness in a chronic model of allergic asthma and in modulation of cognate immune responses. This proposal will take advantage of a series of lines of genetically modified mice to directly examine the role of TGF?? in these effects, to determine the critical cells types responsible, and to identify the molecular mechanisms underlying these responses. Project 2 is based on recent data from Richard Locksley, the project leader, that chitin, a prominent structural component of fungi, parasites and crustaceans, activates macrophages and primes innate immune cells for initiation of type 2 immune responses. Work proposed in this project will utilize a series of novel reporter lines to examine the critical chitin-responsive cells and the mechanisms and relevance of this pathway for initiation of allergic inflammation. Project 3, co-led by Esteban Burchard and John Fahy will follow-up on preliminary observations about genetic associations between sequence variants in chitin-degrading enzymes and TGF?? and allergic sensitization and asthma to more deeply interrogate associations and gene-gene interactions for sequence variants in chitinases and multiple components of the TGF? activation and signaling pathways, including the integrin subunits examined in Project 1. This project will also evaluate the functional significance of associated genes using bronchoalveolar lavage samples and tissue from asthmatic patients and healthy control subjects. These projects will be supported by a Physiology and Tissue Analysis core that will provide extensive support for all 3 projects, and by a centralized Administrative core. Lay summary - This Center will evaluate the mechanisms underlying initiation and persistence of asthma. By identifying novel pathways and molecular targets and testing their relevance to asthma, asthma severity and drug response in humans, the work in the Center should provide clues for the development of new treatments for this common and often devastating disease. PROJECT 1: ?v Integrins in Cognate Immunity and Airway Hyperresponsiveness (SHEPPARD, D) PROJECT 1 DESCRIPTION (provided by applicant): Mice lacking the epithelial integrin, ?v?6, that we have shown activates latent TGF-?, are protected from the persistent airway hyperresponsiveness (AHR) that follows chronic allergen challenge. Surprisingly, this protection is not associated with any decrease in sub-epithelial airway fibrosis, a central TGF-? -dependent feature of this model. Mice with leukocyte specific knockout of the related integrin, ?v?8, which also activates TGF-? show evidence of enhanced adaptive immunity. In this proposal, we will determine whether these altered responses in ?v?6 subunit knockout mice are a direct consequence of loss of the ?v?6 integrin and/or of TGF-? activation from conducting airway epithelial cells using "rescue" mice expressing either the wild type integrin or active TGF-? in airway epithelial cells. We will evaluate the effects of ?v?6 antibodies and a TGF-? RII-lg chimera on these same endpoints to further confirm the importance of this pathway and evaluate the feasibility of targeting this pathway for therapeutic intervention. To determine the mechanisms by which loss of ?v?6 protects from induction of AHR, we will evaluate the relationship between airway responsiveness and expression of a small number of candidate genes identified as linked to this phenotype in preliminary experiments utilizing expression microarrays. We will also determine the cellular distribution of expression by immunostaining and/or in situ hybridization, and will evaluate functional significance using commercially available lines of mice expressing null mutations of specific candidates. Because the cytokine IL-13 is known to play a central role in induction of AHR in multiple models, and because two of the most promising candidates identified by microarrays, leukotrienes C4 synthase and interleukin-18 have been suggested to be upstream of IL-13 induction in the airways, we will also examine the cellular sources of IL-13 in chronically challenged wild type and ?v?6 knockout mice. Finally, we will determine how loss of leukocyte ?v?8 leads to enhancement of adaptive immunity and examine the relevance of this pathway to allergic airway inflammation and its consequences. Lay summary - This project will examine how a single growth factor, transforming growth factor ?, can either contribute to development of chronic asthma or inhibit allergic sensitization and its consequences, depending on where and how this growth factor is activated.