Host immunity to commensal gut fungi

描述(申请人提供)：许多研究记录了特定肠道细菌在调节粘膜免疫和指导组织发育和修复方面发挥的重要作用，但我们对肠道真菌如何与免疫系统相互作用或导致肠道炎症性疾病知之甚少。对肠道微生物进行分类的研究通常集中在细菌上，术语“肠道细菌”和“肠道微生物组”经常互换使用。更好地了解肠道真菌在健康和疾病中的作用的两个障碍是：对肠道真菌的数量和类型有很好的认识，以及有一个可以操纵肠道真菌免疫反应的模型。我的实验室一直在研究β-葡聚糖受体Dectin-1在宿主防御中的作用。Dectin-1在巨噬细胞和树突状细胞上表达，对抵御真菌是必不可少的。Dectin-1通过一种名为CARD9的细胞内信号转导分子发出炎症反应信号，这种蛋白质的特定基因变异与溃疡性结肠炎和克罗恩病密切相关。我们观察到，缺乏Dectin-1的小鼠比野生型小鼠更容易患上DSS诱导的急性结肠炎，这种增强的敏感性是由于肠道真菌。我们已经开始通过高通量多标记焦磷酸测序来表征肠道真菌的微生物区系，并已经鉴定了数百种肠道真菌。因此，我们正在开发一种肠道真菌的数量和类型的感觉，以及一种可以控制肠道真菌免疫反应的模型。我们的总体假设是，β-葡聚糖受体Dectin-1负责研究真菌的肠道微生物区系，并协调宿主免疫反应，塑造微生物区系，促进肠道炎症条件。我们将从四个方面探讨这一假说。在……里面 目的1研究静息和炎症状态下野生型、Dectin-1-/-和CARD9-/-小鼠的真菌菌群特征。在目标2中，我们将确定Decitn-1在采样肠道真菌中的作用以及肠道真菌在驱动炎症反应中的作用。在目标3中，我们将确定缺乏CARD9的小鼠是否表现出与Dectin-1基因敲除小鼠相同的真菌驱动的肠道炎症。在目标4中，我们将确定Dectin-1和CARD9基因敲除小鼠是否也表现出对自发性疾病和T细胞转移引起的疾病的易感性增加。 公共卫生相关性：肠道中充满了微生物，发现的微生物数量和种类可能是导致肠道慢性炎症性疾病(如炎症性肠病)的重要因素。虽然许多研究都集中在免疫系统如何检测肠道细菌，但对肠道真菌是如何检测的知之甚少。这项研究旨在确定在小鼠肠道中发现的真菌的谱系，并使用缺乏特定基因的小鼠来了解免疫系统如何与肠道真菌相互作用。

DESCRIPTION (provided by applicant): Many studies have documented the essential role that specific intestinal bacteria play in tuning mucosal immunity and in instructing tissue development and repair, but we know very little about how intestinal fungi interact with the immune system or contribute to intestinal inflammatory diseases. Studies cataloging intestinal microbes have typically focused on the bacteria, and the terms "intestinal bacteria" and "intestinal microbiome" are often used interchangeably. Two barriers to developing a better understanding of the role of gut fungi in health and disease are having a good sense of the numbers and types of fungi in the gut and having a model in which immune responses to gut fungi can be manipulated. My laboratory has been studying the role of the ?-glucan receptor Dectin-1 in host defense. Dectin-1 is expressed on macrophages and dendritic cells and is essential for defense against fungi. Dectin-1 signals inflammatory responses through an intracellular signaling adaptor molecule called CARD9, a protein for which specific genetic variants are strongly associated with ulcerative colitis and Crohn's disease. We have observed that mice lacking Dectin-1 are more susceptible to acute colitis induced by DSS than wild type mice and that this enhanced sensitivity is due to intestinal fungi. We have begun to characterize the intestinal fungal microflora by high throughput multitag pyrosequencing and have identified several hundred intestinal fungi. Thus, we are developing a sense of the numbers and types of fungi in the gut and a model in which immune responses to gut fungi can be manipulated. Our overall hypothesis is that the ?-glucan receptor Dectin-1 is responsible for surveying the gut microflora for fungi and orchestrating a host immune response that shapes the microflora and contributes to intestinal inflammatory conditions. We will explore this hypothesis in four aims. In aim 1 we will characterize the fungal microbiome in wild type, Dectin-1-/-, and CARD9-/- mice in resting and inflamed conditions. In aim 2 we will define the role of Decitn-1 in sampling intestina fungi and the role of intestinal fungi in driving inflammatory responses. In aim 3 we will determine whether mice lacking CARD9 exhibit the same fungal-driven intestinal inflammation as observed in Dectin-1 knockout mice. In aim 4 we will determine whether Dectin-1 and CARD9 knockout mice also exhibit enhanced susceptibility to spontaneous disease and disease induced by T cell transfer. PUBLIC HEALTH RELEVANCE: The intestines are full of microbes, and the numbers and kinds of microbes found there can be a significant factor in intestinal chronic inflammatory disease such as Inflammatory Bowel Disease. While many studies have focused on how intestinal bacteria are detected by the immune system, little is known about how intestinal fungi are detected. This study aims to define the repertoire of fungi found in mouse intestines and use mice lacking specific genes to understand how the immune system interacts with intestinal fungi.