Secretory Phospholipase A2s in Airway Pathophysiology

描述（由申请人提供）：磷脂酶A2s (PLA2)s是一组酶，催化二十烷类物质如白三烯（LT）s和前列腺素（PG）s形成的限速步骤。这项持续支持的应用侧重于分泌磷脂酶A2组X （sPLA2-X）在哮喘病理生理中的作用。在之前的资助周期中，我们提出了一个新的假设，即气道上皮通过sPLA2s的表达调节类二十烷酸的产生。目前已知的哺乳动物sPLA2s共有10个。根据我们的研究，sPLA2- x是在气道中表达的主要sPLA2。sPLA2-X蛋白在哮喘患者气道衬液中表达量增加，并在气道上皮中强烈表达。此外，我们发现sPLA2-X可在哮喘相关的嗜酸性粒细胞和肥大细胞等靶细胞中启动LT合成。小鼠模型表明sPLA2-X对于卵清蛋白诱导的气道炎症和气道高反应性（AHR）的发展是必需的。我们提供了sPLA2-X在尘螨诱导的气道炎症和巨噬细胞极化的发展中所必需的新数据。在本应用中，我们努力进一步阐明sPLA2-X在哮喘中引发气道炎症和介导支气管收缩的机制。我们的主要假设是，上皮来源的sPLA2-X对于过敏原诱导的气道炎症的发展是必要的，并且在炎症气道中作为支气管收缩的启动物。一个推论是sPLA2-X通过巨噬细胞极化在吸入过敏原的适应性免疫反应中起关键作用。在Specific Aim 1中，我们关注上皮来源的sPLA2-X在过敏原诱导的气道免疫病理发展中的特定作用，并检查上皮sPLA2-X在致敏期和效应期的功能。利用原代人上皮细胞，我们研究了sPLA2-X的分泌和激活调控。在Specific Aim 2中，我们研究了sPLA2-X在巨噬细胞向M2表型极化中的作用，以及sPLA2-X巨噬细胞轴在对过敏原的适应性免疫反应中的确切作用。在Specific Aim 3中，我们在豚鼠模型中使用sPLA2-X的一种新型药理抑制剂对sPLA2-X在高呼吸诱导的支气管收缩中的作用进行了转化研究。这些研究将为了解由上皮介导的过敏原诱导的气道功能障碍的机制提供重要见解，并为进一步开发通过选择性抑制sPLA2-X治疗哮喘的新方法奠定坚实的基础。

DESCRIPTION (provided by applicant): The phospholipase A2s (PLA2)s are a group of enzymes that catalyze the rate-limiting step in the formation of eicosanoids such as leukotrienes (LT)s and prostaglandins (PG)s. This application for sustained support focuses on secreted phospholipase A2 group X (sPLA2-X) in the pathophysiology of asthma. During the prior funding cycle, we addressed the novel hypothesis that the airway epithelium serves as a regulator of eicosanoid production through the expression of sPLA2s. A total of 10 mammalian sPLA2s have been described. From our research, sPLA2-X emerged as the dominant sPLA2 expressed in the airways. The amount of sPLA2-X protein is increased in the airway lining fluid of patients with asthma, and is strongly expressed in the airway epithelium. Further, we found that sPLA2-X initiates LT synthesis in target cells including eosinophils and mast cells implicated in asthma. Murine models indicate that sPLA2-X is necessary for the development of ovalbumin-induced airway inflammation and airway hyperresponsiveness (AHR). We provide new data that sPLA2-X is necessary for the development of house dust mite induced airway inflammation as well as macrophage polarization. In this application we strive to further elucidate the mechanism by which sPLA2-X initiates airway inflammation and mediates bronchoconstriction in asthma. Our primary hypothesis is that epithelial-derived sPLA2-X is necessary for the development of allergen- induced airway inflammation and serves as an initiator of bronchoconstriction in inflamed airways. A corollary hypothesis is that sPLA2-X plays a crucial role in the adaptive immune response to inhaled allergen through macrophage polarization. In Specific Aim 1 we focus on the specific role of epithelial- derived sPLA2-X during the development of allergen-induced airway immunopathology, and examine the function of epithelial sPLA2-X during the sensitization versus effector phases. Using primary human epithelial cells, we examine the regulation of secretion and activation of sPLA2-X. In Specific Aim 2, we examine the role of sPLA2-X in macrophage polarization towards a M2 phenotype, and the precise role of the sPLA2-X macrophage axis in the adaptive immune response to allergen. In Specific Aim 3, we conduct a translational study on the role of sPLA2-X during hyperpnea-induced bronchoconstriction using a novel pharmacological inhibitor of sPLA2-X in a guinea pig model. These studies will provide important insights into the mechanism of allergen-induced airway dysfunction mediated by the epithelium and a strong basis for the further development of a new approach to treating asthma through the selective inhibition of sPLA2-X.