Mechanisms of Human Basophil-Mediated Allergic Inflammation

描述（由申请人提供）：在过去的20年里，本实验室的总体目标是阐明调节过敏性炎症的机制，从而确定治疗过敏性疾病的新靶点。本课题将重点研究人类嗜碱性细胞激活的调控机制及其在变态反应性疾病中的作用。嗜碱性粒细胞是循环中最不丰富的粒细胞，直到最近才有证据表明，嗜碱性粒细胞具有强大的效应功能，可以连接先天免疫和适应性免疫，并参与过敏性和自身免疫性疾病的发病机制。初步研究表明，IL-3是使嗜碱性细胞极化的关键细胞因子，其效应功能包括对FcεR1交联的脱颗粒反应、细胞表面分子表达的调节、细胞因子表达和免疫调节。关键的初步发现包括：1)详细分析了IL-3对人嗜碱性细胞的激活作用，证明了IL-3诱导的嗜碱性细胞表型亚群具有不同的功能特征；2)人类嗜碱性粒细胞表达胸腺基质淋巴生成素受体（TSLPR）及其信号通路的第一个直接证据，TSLPR受IL-3和IL-33调控；3)嗜碱性细胞“功能耐受”受IL-3调控的证据。本提案将探讨靶向IL-3活化嗜碱性细胞是治疗嗜碱性细胞介导的过敏性疾病的有效策略的中心假设。研究将使用来自健康对照和过敏性疾病患者的人类嗜碱性粒细胞，以及来自IL-3缺陷和对照小鼠的小鼠嗜碱性粒细胞，以及最先进的细胞和分子技术。中心假设将通过测试以下四个推论假设进行调查：目的1：研究在缺乏IL-3的情况下，嗜碱性细胞处于“功能耐受”状态，IL-3激活嗜碱性细胞打破“功能耐受”并导致异质亚群的假设，这些亚群可能处于顺序激活状态或随机不同的亚群；目的2：探讨IL-3激活的嗜碱性细胞对TSLP的反应并获得极化诱导Th2免疫反应的功能表型的假设；目的3：探讨嗜碱性细胞的IL-3激活状态决定了嗜碱性细胞激活试验在评估临床特应性和“功能耐受”方面的敏感性的假设；目的4：研究IL-3的拮抗或缺乏会导致嗜碱性粒细胞“功能耐受”的假设，在小鼠和新的体外人类特应性模型中。这些研究有可能描述嗜碱性细胞为不同效应功能而被激活的机制，为临床评估嗜碱性细胞激活提供新的检测方法，并为潜在的靶向IL-3作为过敏性疾病的新治疗方法提供概念证明。

DESCRIPTION (provided by applicant): The overall goal of this laboratory over the past 20 years has been the elucidation of mechanisms regulating allergic inflammation and thereby identification of novel targets for treating allergic diseases. This proposal will focus on mechanisms regulating human basophil activation and effector function in allergic diseases. Basophils are the least abundant granulocytes in the circulation, and only recently has evidence demonstrated that basophils have potent effector functions that bridge innate and adaptive immunity and contribute to the pathogenesis of both allergic and autoimmune diseases. Preliminary studies demonstrate that IL-3 is a key cytokine for polarizing basophils for effector functions that include degranulation in response to FcεR1 crosslinking, regulation of cell surface molecule expression, cytokine expression, and immune modulation. Key preliminary findings include: 1) detailed analysis of IL-3 activation of human basophils that demonstrates IL-3-inducible phenotypic subsets of basophils with distinct functional characteristics; 2) the first direct evidence for human basophil expression of the thymic stromal lymphopoietin receptor (TSLPR) and signaling in response to TSLP, which is regulated by IL-3 and IL-33; and 3) evidence for basophil "functional tolerance' regulated by IL-3. This proposal will investigate the central hypothesis that targeting IL-3 activation of basophils is an effective strategy for treatin basophil-mediated allergic diseases. Studies will use human basophils from healthy controls and patients with allergic diseases, as well as murine basophils from IL-3 deficient and control mice, and state-of-the-art cellular and molecular techniques. The central hypothesis will be investigated by testing the following four corollary hypotheses: Aim 1: Investigate the hypothesis that in the absence of IL-3, basophils are in a state of "functional tolerance", and that IL-3 activation of basophils breaks "functional tolerance" and results in heterogeneous subpopulations which may be either in sequential states of activation or stochastically distinct subpopulations; Aim 2: Investigate the hypothesis that IL-3 activated basophils respond to TSLP and acquire a functional phenotype that is polarized for inducing Th2 immune responses; Aim 3: Investigate the hypothesis that the IL-3 activation state of basophils determines the sensitivity o basophil activation testing for assessment of clinical atopy versus "functional tolerance"; and Aim 4: Investigate the hypothesis that antagonism, or lack, of IL-3 will result in basophil "functional tolerance" in [a murine model of atopy and a novel in vitro human model of atopy.] These studies have the potential to delineate the mechanisms by which basophils are activated for distinct effector functions, lead to novel assays for clinical evaluation of basophil activatio, and provide proof-of- concept for potentially targeting IL-3 as a novel treatment of allergic disorders.