The Role of the Major Alternaria Allergen Alt_a_1 in Airway Inflammation

描述（由申请人提供）：哮喘中的气道炎症反应可能是免疫细胞对环境因素（如空气传播的真菌）失调的结果。本项目的长期目标是更好地了解哮喘中Th 2型气道炎症的病理生理机制。长期以来，接触真菌链格孢菌与人类哮喘的发生和恶化有关。在鼻内暴露于链格孢属孢子和单个蛋白质后，幼稚小鼠表现出显著的嗜酸性气道炎症，增强的Th 2对无害抗原的敏感性和气道高反应性。尽管链格孢属在过敏性气道疾病（如哮喘）的发生、发作和恶化中的临床重要性已得到充分证实，但对单个真菌产物在这些病理状态中的作用知之甚少。过敏原摄取和通过上皮细胞层移动（内吞作用和转胞吞作用）的重要性和详细机制尚未在很大程度上进行探索。这个创新项目的重点是分泌的主要链格孢变应原Alt_a_1。它将通过利用支气管肺泡上皮细胞和小鼠气道炎症模型来评估Alt_a_1在过敏性疾病中的作用。我们已经发现Alt_a_1是促炎性的，并且具有促进与细胞表面PI-3-P结合和细胞进入的独特氨基酸基序（RXLR）。在目的1中，将研究Alt_a_1在体外和哮喘小鼠模型中的先天性和适应性免疫应答中的作用。将检查重组Alt_a_1蛋白和缺乏Alt_a_1的真菌敲除突变体的作用。在具体目标2中，将表征Alt_a_1的酯酶活性和RXLR基序在细胞进入和免疫应答中的重要性。重组Alt_a_1将用于确定酯酶活性、PI-3-P结合和细胞进入所需的氨基酸残基。将研究用Alt_a_1蛋白处理后的上皮细胞免疫应答。该项目将导致更好地了解持续性和复发性气道炎症的机制，并可能导致更具体和有效的治疗和预防策略的发展，特别是如果PI-3-P介导的细胞进入证明对变应原性具有普遍重要性。

DESCRIPTION (provided by applicant): The inflammatory airway response in asthma may be the result of immune cells that are dysregulated towards environmental factors such as airborne fungi. The long-term goal of this project is to better understand the pathophysiological mechanisms of Th2-type airway inflammation in asthma. Exposure to the fungus, Alternaria, has long been implicated in the development and exacerbation of human asthma. After intranasal exposure to Alternaria spores and individual proteins, naive mice exhibit marked eosinophilic airway inflammation, enhanced Th2 sensitization to innocuous antigens, and airway hyperreactivity. Despite the well-documented clinical importance of Alternaria in the development, onset, and exacerbation of allergic airway diseases such as asthma, little knowledge exists about the role of individual fungal products in these pathological states. The importance of and detailed mechanisms of allergen uptake and movement through the epithelial cell layer (endocytosis and transcytosis) have not been explored to any great extent. This innovative project focuses on the secreted major Alternaria allergen Alt_a_1. It will assess the role of Alt_a_1 in allergic disease by utilizing bronchoalveolar epithelial cells and murine models of airway inflammation. We have discovered that Alt_a_1 is proinflammatory and harbors a unique amino acid motif (RXLR) that facilitates binding to cell surface PI-3-P and cellular entry. In aim 1 the role of Alt_a_1 in innate and adaptive immune responses in vitro and in murine models of asthma will be investigated. The effects of recombinant Alt_a_1 protein and fungal knockout mutants lacking Alt_a_1 will be examined. In specific aim 2 the importance of the Alt_a_1's esterase activity and RXLR motif in cellular entry and immunological responses will be characterized. Recombinant Alt_a_1 will be used to define amino acid residues required for esterase activity, for PI-3-P binding, and for cellular entry. Epithelial cell immune responses following treatment with the Alt_a_1 proteins will be investigated. This project will lead to a better understanding of the mechanisms of persistent and recurrent airway inflammation and may lead to the development of more specific and effective therapies and prevention strategies, especially if PI-3-P-mediated cell entry proves of general importance to allergenicity.