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活化。在与过敏性炎症相关的介质中，嗜酸性粒细胞是类二十烷酸的来源，包括半胱氨酰白三烯。半胱氨酰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囊泡转运介导的细胞因子（包括过敏性疾病相关细胞因子IL-4）从嗜酸性粒细胞颗粒库释放的自分泌细胞内介质。嗜酸性粒细胞和其他体内与炎症反应相关的白细胞：1）表现出尚不清楚的“引发”反应，通过该反应，这些白细胞对激动剂的反应更显著，并可产生更大量的类二十烷酸; 2）特征性地含有增加数量的细胞内脂质体。体外研究表明，脂质体是高度调节的、可诱导的细胞器，并且是参与嗜酸性粒细胞和其他细胞对提高类花生酸形成的引发反应的位点。虽然脂质体普遍存在于与炎症相关的体内嗜酸性粒细胞和白细胞中，但在过敏性炎症部位的体内嗜酸性粒细胞内脂质体的形成和功能从未被研究过。拟定的研究将利用完善的过敏性炎症体内模型研究嗜酸性粒细胞活化的机制，并检验细胞内脂质体形成主要参与炎症反应中嗜酸性粒细胞活化的假设。研究将调查嗜酸性粒细胞脂质体在过敏性炎症中的体内形成和功能，具有四个具体目标：1）调查过敏性炎症的鼠模型中嗜酸性粒细胞脂质体形成的分子途径; 2）表征体内引发的鼠嗜酸性粒细胞脂质体的炎症相关组分; 3）评价脂质体在小鼠嗜酸性粒细胞中类二十烷酸生成和自分泌及旁分泌信号传导中的功能作用;和4）评价作为抗炎/抗过敏药物开发靶点的脂质体形成途径，包括具体研究巴西雨林植物衍生的生物活性产物对脂质体形成和类二十烷酸产生的影响。这些研究旨在为嗜酸性粒细胞活化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，将利用巴西研究者的过敏性炎症体内模型专业知识，以扩展NIH资助#RO 1 AI 20241中的人嗜酸性粒细胞体外研究。

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.