Dectin-1 and Immunity Against Pneumocystis Carinii

描述(由申请人提供)：从肺环境中清除卡氏肺孢子虫是肺泡巨噬细胞的唯一责任。卡氏肺孢子虫是导致免疫功能低下的人肺炎的重要原因。然而，由于卡氏肺孢子虫不能在体外稳定培养，到目前为止，还没有高通量的活性检测来阐明细胞介导的天然宿主防御机制。利用一种新的体外杀伤实验，我们发现肺泡巨噬细胞对卡氏肺孢子虫的识别和随后的非光学杀伤是通过一种新描述的真菌β-葡聚糖受体Dectin-1来实现的。Dectin-1是一种28 kDa的II型跨膜受体，含有单一的凝集素样糖识别结构域，识别β1，3连接和β1，6连接的葡聚糖。我们还观察到肺泡巨噬细胞对卡氏肺孢子虫的炎症反应是通过Dectin-1识别来介导的。我们进一步表明，未成熟的肺来源的树突状细胞表达高水平的Dectin-1。在这些研究的基础上，我们推测Dectin-1是抗卡氏肺孢子虫的非调理肺泡巨噬细胞效应所必需的，也是树突状细胞介导的针对卡氏肺孢子虫的适应性T细胞反应的激活所必需的。我们将通过以下具体目标来检验这一假设。具体目的1：验证Dectin-1介导的卡氏肺孢子虫识别是肺泡巨噬细胞体外防御卡氏肺孢子虫的关键。具体目标2：测试β-葡聚糖识别在卡氏肺孢子虫引起的肺部炎症中所需的概念。具体目的3：测试阻断Dectin-1介导的卡氏肺孢子虫识别增加卡氏肺孢子虫肺部感染易感性的概念。这些研究将探索一种新的真菌分子识别受体，并表征其在体外和体内对抗机会性真菌生物体卡氏P.carinii的作用，并可能为免疫系统如何识别P.carinii提供新的见解，这可能导致新的免疫治疗策略来对抗这种毁灭性的肺部感染。

DESCRIPTION (provided by applicant): Elimination of Pneumocystis carinii, a significant cause of pneumonia in immunocompromised individuals, from the pulmonary environment is the exclusive responsibility of the alveolar macrophage. However, due to P. carinii's inability to be stably cultured in vitro, to date, there has been no high-throughput assay of viability to elucidate innate cell-mediated host defense mechanisms against P. carinii. Using a novel in vitro killing assay, we discovered that recognition and subsequent non-opsonic killing of P. carinii by alveolar macrophages occurs via a newly described receptor for fungal beta-glucans, Dectin-1. Dectin-1 is a 28 kDa, type II transmembrane receptor that contains a single lectin-like carbohydrate recognition domain which recognizes beta 1,3-linked and beta 1,6-linked glucans. We also observed that the alveolar macrophage inflammatory response to P. carinii is mediated by Dectin-1 recognition. We further show that immature lung-derived dendritic cells express high levels of Dectin-1. Based on these studies, we hypothesize that Dectin-1 is required for non-opsonic alveolar macrophage effector function against P. carinii as well as dendritic cell-mediated activation of adaptive T cell responses against P. carinii. We will test this hypothesis with the following specific aims. Specific Aim 1: To test the concept that Dectin-1 mediated recognition of P. carinii is critical for alveolar macrophage host defense against P. carinii in vitro. Specific Aim 2: To test the concept that beta-glucan recognition is required for P. carinii-induced pulmonary inflammation. Specific Aim 3: To test the concept that interruption of Dectin-1 mediated P. carinii recognition increases susceptibility to lung infection with P. carinii. These studies will investigate a new fungal molecular recognition receptor and characterize its role, in vitro as well as in vivo, against the opportunistic fungal organism P. carinii and may provide new insight into how P. carinii is recognized by the immune system, which may lead to novel immunotherapeutic strategies to combat this devastating pulmonary infection.