The Role of the Major Alternaria Allergen Alt_a_1 in Airway Inflammation

描述(申请人提供)：哮喘的炎性呼吸道反应可能是免疫细胞对环境因素(如空气中的真菌)调节失调的结果。该项目的长期目标是更好地了解哮喘患者Th2型呼吸道炎症的病理生理机制。长期以来，人们一直认为，接触交链孢属真菌与人类哮喘的发展和恶化有关。鼻腔接触交链孢子和单个蛋白后，幼龄小鼠表现出明显的嗜酸性呼吸道炎症，增强了Th2对无害抗原的敏感性，并表现出呼吸道高反应性。尽管交链孢霉在哮喘等过敏性呼吸道疾病的发生、发病和加重中的临床重要性已经得到了很好的证明，但对单个真菌产品在这些病理状态中的作用知之甚少。过敏原通过上皮细胞层摄取和移动(内吞和跨细胞)的重要性和详细机制尚未在很大程度上被探索。这一创新项目的重点是分泌型交链孢属主要过敏原Alt_a_1。它将通过利用支气管肺泡上皮细胞和小鼠呼吸道炎症模型来评估Alt_a_1在过敏性疾病中的作用。我们发现Alt_a_1是促炎性的，并且含有一个独特的氨基酸基序(RXLR)，它促进了与细胞表面PI-3-P的结合和细胞进入。目的1研究Alt_a_1在天然免疫反应和获得性免疫反应中的作用以及在哮喘小鼠模型中的作用。将检测重组Alt_a_1蛋白和缺失Alt_a_1的真菌基因敲除突变体的效果。在特定目标2中，将表征Alt_a_1‘S酯酶活性和RXLR基序在细胞进入和免疫反应中的重要性。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。用Alt_a_1蛋白处理后的上皮细胞免疫反应将被研究。该项目将有助于更好地了解持续性和复发性呼吸道炎症的机制，并可能导致更具体和有效的治疗和预防策略的开发，特别是如果PI-3-P介导的细胞进入被证明对过敏性具有普遍重要性。

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.