Eosinophil Lipid Bodies in Allergic Inflammation

过敏性疾病的发病机制的核心是嗜酸性粒细胞在过敏性炎症部位的募集和激活。在与过敏性炎症有关的介质中，嗜酸性粒细胞是二十烷类化合物的来源，包括半胱氨酰白三烯。半胱氨酰白三烯既是变态反应性炎症的主要旁分泌介质，也是最近才认识到的自分泌细胞内介质，调节囊泡运输介导的细胞因子的释放，包括与过敏性疾病相关的细胞因子IL-4，从嗜酸性粒细胞储存库中释放。体内与炎症反应有关的嗜酸性粒细胞和其他白细胞：1)嗜酸性粒细胞和其他白细胞表现出“启动”反应，这些反应对激动剂有更显著的反应，并能产生更多的二十烷基类化合物；2)特征是细胞内脂质小体数量增加。体外研究表明，脂体是高度受调控的、可诱导的细胞器，也是嗜酸性粒细胞和其他细胞增加嗜酸性粒细胞形成二十烷样物质的启动反应的部位。尽管体内与炎症相关的嗜酸性粒细胞和白细胞中普遍存在脂体，但体内变态反应性炎症部位的嗜酸性粒细胞内脂体的形成和功能尚未得到研究。建议的研究将利用已建立的过敏性炎症体内模型来研究嗜酸性粒细胞激活的机制，并验证细胞内脂体形成在炎症反应中与嗜酸性粒细胞激活密切相关的假说。研究将研究变态反应性炎症中嗜酸性粒细胞脂体的形成和在体内的功能，具体目的有四个：1)在变态反应性炎症小鼠模型中调查嗜酸性粒细胞脂体形成的分子途径；2)表征体内激发的小鼠嗜酸性粒细胞脂体的炎症相关成分；3)评估脂体在嗜酸性粒细胞生成和自分泌和旁分泌信号中的功能作用；4)评价作为抗炎/抗过敏药物开发靶点的脂体形成途径，包括特别研究巴西雨林植物衍生的生物活性产品对脂体形成和二十烷类化合物生成的影响。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，并潜在地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在体内过敏性炎症模型方面的专业知识，在NIH#RO1 AI20241号拨款中扩大对人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.