Eosinophil Lipid Bodies in Allergic Inflammation

过敏性疾病发病机制的核心是过敏性炎症部位嗜酸性粒细胞的募集和激活。在与过敏性炎症相关的介质中，嗜酸性粒细胞是类二十烷的来源，包括半胱氨酸白三烯。半胱氨酸白三烯既是过敏性炎症的主要旁分泌介质，也是最近才认识到的调节细胞内自分泌介质，通过囊泡运输介导细胞因子的释放，包括来自嗜酸性粒细胞颗粒储存的过敏性疾病相关细胞因子IL-4。在体内与炎症反应相关的嗜酸性粒细胞和其他白细胞：1)表现出迄今尚不清楚的“启动”反应，通过这种反应，这些白细胞对激动剂的反应更明显，可以产生更多数量的类二十烷酸；2)细胞内脂质体数量增加。体外研究表明，脂质小体是高度调控的、可诱导的细胞器，是参与嗜酸性粒细胞和其他细胞形成的高类二十烷的启动反应的位点。尽管脂质体在体内与炎症相关的嗜酸性粒细胞和白细胞中普遍存在，但在体内过敏性炎症部位的嗜酸性粒细胞中脂质体的形成和功能从未被研究过。本研究将利用成熟的体内变应性炎症模型来研究嗜酸性粒细胞激活的机制，并验证细胞内脂质体形成在炎症反应中主要参与嗜酸性粒细胞激活的假设。研究将探讨过敏性炎症中嗜酸性粒细胞脂体的形成和体内功能，具体目的有四个：1)研究小鼠变应性炎症模型中嗜酸性粒细胞脂体形成的分子途径；2)表征体内诱导的小鼠嗜酸性粒细胞脂质体炎症相关成分；3)评估脂质体在类二十烷生成和小鼠嗜酸性粒细胞自分泌和旁分泌信号传导中的功能作用；4)评估脂质体形成的途径，作为抗炎/抗过敏药物开发的靶点，包括专门研究巴西雨林植物源性生物活性产品对脂质体形成和类二十烷酸生成的影响。这些研究旨在为嗜酸性粒细胞激活的基本细胞内机制提供新的见解，并可能确定新的抗炎治疗靶点。这些研究将在巴西进行，将利用巴西研究人员的体内过敏性炎症模型的专业知识，扩展NIH资助# RO1 AI20241中人类嗜酸性粒细胞的体外研究。

Central to the pathogenesis of allergic diseases are both the recruitment and activation of eosinophils at sites of allergic inflammation. Among mediators pertinent to allergic inflammation, eosinophils are sources of eicosanoids, including cysteinyl leukotrienes. Cysteinyl leukotrienes are both major paracrine mediators of allergic inflammation and, as only recently recognized, autocrine intracellular mediators regulating vesicular transport-mediated release of cytokines, including the allergic disease pertinent cytokine, IL-4, from eosinophil granule stores. Eosinophils and other leukocytes associated in vivo with inflammatory reactions: l) exhibit, as yet poorly understood, "priming" responses, by which these leukocytes respond more prominently to agonists and can generate greater quantities of eicosanoids; and 2) characteristically contain increased numbers of intracellular lipid bodies. In vitro studies have indicated that lipid bodies are highly regulated, inducible organelles and are sites involved in the priming responses for heightened eicosanoid formation by eosinophils and other cells. Although lipid bodies are ubiquitous in eosinophils and leukocytes in vivo associated with inflammation, the formation and function of lipid bodies within eosinophils in vivo in sites of allergic inflammation have never been investigated. The proposed studies will utilize well- established in vivo models of allergic inflammation to investigate mechanisms of eosinophil activation and to test the hypothesis that intracellular lipid body formation is centrally involved in eosinophil activation in inflammatory responses. Studies will investigate eosinophil lipid body formation and functioning in vivo in allergic inflammation, with four specific aims: 1) investigate molecular pathways of eosinophil lipid body formation in murine models of allergic inflammation; 2) characterize inflammation pertinent components of in vivo-elicited murine eosinophil lipid bodies; 3) evaluate functional roles of lipid bodies in eicosanoid generation and autocrine and paracrine signaling in murine eosinophils; and 4) evaluate pathways of lipid body formation as targets for anti-inflammatory/anti- allergic drug development, including specifically investigating the effects of Brazilian rain forest plant-derived bioactive products on lipid body formation and eicosanoid generation. These studies aim to provide new insights into fundamental intracellular mechanisms of eosinophil activation and potentially identify novel anti-inflammatory therapeutic targets. These studies, to be performed in Brazil, will utilize the expertise of Brazilian investigators with in vivo models of allergic inflammation to extend in vitro studies of human eosinophils in NIH grant # RO1 AI20241.