Secretory Phospholipase A2s in Airway Pathophysiology

描述(申请人提供)：磷脂酶A2(PLA2)S是一组酶，催化形成二十烷类化合物的限速步骤，如白三烯(LT)S和前列腺素(PG)S。这项持续支持的应用重点是分泌型磷脂酶A2组X(SLA2-X)在哮喘的病理生理中的作用。在之前的资金周期中，我们提出了一个新的假设，即呼吸道上皮通过sPLA2的表达作为二十烷类化合物产生的调节因子。总共描述了10种哺乳动物的sPLA2。根据我们的研究，sPLA2-X是在呼吸道中表达的主要sPLA2。哮喘患者气道衬里液中sPLA2-X蛋白含量增加，并在呼吸道上皮细胞中强表达。此外，我们发现sPLA2-X在靶细胞中启动LT的合成，包括与哮喘有关的嗜酸性粒细胞和肥大细胞。小鼠模型表明，sPLA2-X在卵白蛋白诱导的气道炎症和气道高反应性(AHR)的发展过程中是必需的。我们提供了新的数据，即sPLA2-X在屋尘螨引起的呼吸道炎症和巨噬细胞极化的发展过程中是必要的。在这一应用中，我们努力进一步阐明sPLA2-X在哮喘中启动呼吸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在过敏原诱导的呼吸道炎症的发展中是必需的，并在炎症的呼吸道中作为支气管收缩的启动子。一个推论是，sPLA2-X通过巨噬细胞极化在吸入性变应原的适应性免疫反应中发挥关键作用。在具体目标1中，我们重点研究了上皮源性sPLA2-X在过敏原诱导的呼吸道免疫病理过程中的特定作用，并检测了上皮源性sPLA2-X在致敏与效应阶段的功能。利用原代人上皮细胞，我们研究了sPLA2-X的分泌和激活的调节。在特定的目标2中，我们研究了sPLA2-X在巨噬细胞极化向M2表型转变中的作用，以及sPLA2-X巨噬细胞轴在变应原适应性免疫反应中的确切作用。在具体目标3中，我们使用一种新的药物抑制剂sPLA2-X在豚鼠模型上进行了一项关于sPLA2-X在高呼吸暂停诱导的支气管收缩中的作用的翻译研究。这些研究将为进一步开发选择性抑制sPLA2-X治疗哮喘的新途径提供重要依据。

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.