Regulation of Macrophage Activation by House Dust Mite

描述(由申请人提供)： 曾在伊拉克服役的美国士兵患过敏性鼻炎和哮喘的风险增加。与本土驻扎人员相比，部署在波斯湾的士兵患过敏性鼻炎的风险是前者的两倍，患哮喘的风险是后者的1.6倍。此外，12岁以后有症状的哮喘的诊断是入伍的排除标准。虽然过敏性炎症性疾病风险增加的原因尚未确定，但暴露在高水平的粉尘和其他可吸入颗粒物中被认为是最可能的解释。在伊拉克服役的士兵的帐篷中发现了普遍存在的环境过敏原--屋尘螨(HDM)，它被认为是哮喘的主要诱因。据估计，50%-80%的鼻炎和哮喘是由HDM引起的；然而，HDM诱发和加重哮喘的机制尚不完全清楚。HDM和许多其他可吸入颗粒物含有刺激性结构，我们称之为过敏原相关分子模式(AAMPS)，它参与并刺激先天模式识别受体(PRR)。虽然其他人研究了HDM对上皮细胞和树突状细胞的影响，但我们发现HDM直接激活巨噬细胞，巨噬细胞是先天免疫系统的中心细胞，在肺部和呼吸道中大量存在。HDM刺激巨噬细胞表达干扰素-β和一些交替激活的巨噬细胞(AAM)特有的基因，包括几丁质酶家族成员，这些基因与过敏性疾病密切相关。因此，我们在这项建议中的总体目标是描述HDM利用的导致巨噬细胞分化的交替激活状态的先天免疫传感系统的特征。对这一过程的了解具有重要的临床意义；人类哮喘患者血液和呼吸道中的AAM数量和几丁质酶蛋白的数量增加，特别是在哮喘加重期间。此外，我们已经证明，在小鼠模型中，AAM启动并放大哮喘的症状。有待检验的中心假设是，在HDM中发现的AAMP阵列激活了天然信号通路，从而协调地导致巨噬细胞中AAM基因的表达，从而增强了过敏和哮喘。1)确定细胞表面感受器在HDM诱导的反应中的作用，2)确定炎症小体和IL-1家族成员在HDM诱导的反应中的作用，3)分析干扰素对HDM诱导的反应的作用，4)通过比较从对照组或哮喘老兵分离的人巨噬细胞的反应来验证HDM对巨噬细胞的影响。这些实验将在体外通过刺激野生型和HDM基因缺陷小鼠制备的巨噬细胞来进行。我们还将分析HDM对人PBMC来源的巨噬细胞的影响。重要的是，一旦我们在体外确定了HDM对巨噬细胞的作用所必需的先天传感器和信号通路，我们将使用HDM诱导的哮喘小鼠模型来分析该传感器在体内巨噬细胞激活和过敏性肺部炎症中的重要性。我们研究的预期结果是，它将描绘由无处不在的环境过敏原HDM激活的信号通路，该信号通路驱动AAM基因的表达。这种知识的增加将使退伍军人和国家受益，因为这些途径可能会导致确定控制HDM引起的过敏性鼻炎和哮喘的新靶点。

DESCRIPTION (provided by applicant): US soldiers who have served in Iraq show an increased risk for allergic rhinitis and asthma. Soldiers deployed in the Persian Gulf had twice the risk of developing allergic rhinitis as compared to homeland stationed personnel and 1.6 times the risk of developing asthma. Furthermore, the diagnosis of asthma with symptoms after the age of 12 years is an exclusion critierion for military enlistment. While the reason for the increased risk for allergic inflammatoy diseases has not been established, exposure to high levels of dust and other inhaled particles is thought to be the most likely explanation. The ubiquitous environmental allergen, house dust mite (HDM), was found in high levels in the tents of soldiers serving in Iraq and is known to be a major inducer of asthma. It has been estimated that between 50-80% of rhinitis and asthma is due to HDM; however, the mechanisms by which HDM induces and exacerbates asthma are not fully understood. HDM and many other inhaled particulates contain stimulatory structures we have termed allergen- associated molecular patterns (AAMPs) that engage and stimulate innate pattern recognition receptors (PRR). While others have studied the effects of HDM on epithelial and dendritic cells, we have found that HDM directly activates macrophages, a cell that is central in the innate immune system and found in abundance in the lungs and airways. HDM stimulates macrophages to induce the expression of IFN-¿ and several genes that are characteristic of alternatively activated macrophages (AAM), including chitinase family members, that are strongly associated with allergic disease. Thus, our overall goal in this proposal is to characterize the innate immune sensing systems utilized by HDM that lead to an alternatively activated state of macrophage differentiation. An understanding of this process is clinically important; human asthmatics have elevated numbers of AAM and increased amounts of chitinase proteins in their blood and airways, especially during asthma exacerbations. Furthermore, we have shown that AAM initiate and amplify the symptoms of asthma in a mouse model. The central hypothesis to be tested is that the array of AAMPs found in HDM activate innate signaling pathways that coordinately lead to the expression of AAM genes in macrophages enhancing allergy and asthma. The specific aims designed to test these hypotheses are 1) to determine the contribution of cell surface sensors in HDM-induced responses, 2) to determine the role of the inflammasome and IL-1 family members in HDM-induced effects, 3) to analyze the contribution of IFN-¿ to the HDM-induced responses, and 4) to validate the effect of HDM on macrophages by comparing responses in human macrophages isolated from controls or asthmatic veterans. These experiments will be performed in vitro by stimulating macrophages prepared from wild type and gene deficient mice with HDM. We will also analyze the effects of HDM on human macrophages derived from PBMC. Importantly, once we identify an innate sensor and signaling pathway that is necessary for HDM-induced effects on macrophages in vitro, we will analyze the importance of the sensor in macrophage activation and allergic lung inflammation in vivo using a mouse model of HDM-induced asthma. The anticipated outcome of our research is that it will delineate the signaling pathways activated by the ubiquitous environmental allergen HDM that drive expression of AAM genes. This increase in knowledge will have benefit for veterans and the nation because these pathways will likely lead to the identification of new targets for the control of HDM-induced allergic rhinitis and asthma.