Secretory Phospholipase A2s in Airway Pathophysiology

描述（由申请人提供）：磷脂酶A2（PLA 2）是一组催化类花生酸形成中限速步骤的酶，如白三烯（LT）和洋地黄素（PG）。这种持续支持的应用集中在哮喘病理生理学中的分泌型磷脂酶A2 X组（sPLA 2-X）。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sPLA 2的表达作为类花生酸产生的调节剂。已经描述了总共10种哺乳动物sPLA 2。根据我们的研究，sPLA 2-X成为气道中表达的主要sPLA 2。sPLA 2-X蛋白在哮喘患者气道衬里液中含量增加，并在气道上皮中强表达。此外，我们发现sPLA 2-X启动LT合成的靶细胞，包括嗜酸性粒细胞和肥大细胞参与哮喘。小鼠模型表明sPLA 2-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。我们提供了新的数据，表明sPLA 2-X对于屋尘螨诱导的气道炎症以及巨噬细胞极化的发展是必要的。在本申请中，我们致力于进一步阐明sPLA 2-X在哮喘中启动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sPLA 2-X对于过敏原诱导的气道炎症的发展是必需的，并且充当发炎气道中支气管收缩的引发剂。一个推论假设是sPLA 2-X通过巨噬细胞极化在吸入变应原的适应性免疫应答中起关键作用。在具体目标1中，我们关注上皮来源的sPLA 2-X在过敏原诱导的气道免疫病理学发展过程中的具体作用，并检查上皮sPLA 2-X在致敏与效应阶段的功能。使用原代人上皮细胞，我们研究分泌和激活的sPLA 2-X的调节。在特定目标2中，我们研究了sPLA 2-X在巨噬细胞向M2表型极化中的作用，以及sPLA 2-X巨噬细胞轴在对变应原的适应性免疫应答中的确切作用。在具体目标3中，我们在豚鼠模型中使用新型sPLA 2-X药理学抑制剂对sPLA 2-X在呼吸过度诱导的支气管收缩过程中的作用进行了转化研究。这些研究将提供重要的见解过敏原诱导的气道功能障碍的上皮介导的机制和一个强有力的基础，进一步发展的新方法来治疗哮喘通过选择性抑制sPLA 2-X。

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.