MyD88-independent resistance to Toxoplasma in the intestine

项目摘要/摘要 这项建议的长期目标是了解免疫的诱导和效应机制。 在没有信号适配器MyD88的情况下。我们使用细胞内的原生动物弓形虫作为工具， 一种口服获得性条件致病菌，通常诱导基于Th1型和干扰素-γ的强保护性 豁免权。弓形虫可通过依赖MyD88的TLR11/12途径激活小鼠免疫功能。然而， 人类缺乏这些TLR，MyD88表达缺陷的人群对ALL除了有限的 细菌感染的数量。因此，不涉及MyD88的免疫途径对 理解。我们发现MyD88基因敲除小鼠能够在 弓形虫感染，表明免疫启动的替代途径在小鼠中是活跃的 模特。此外，MyD88基因敲除动物可以通过口服接种疫苗来对抗致命感染 弓形虫。支持MyD88非依赖性免疫的细胞和分子机制是 没有特征的。推动这项研究建议的中心假设是，老鼠的免疫系统 通过MyD88非依赖的途径产生对弓形虫的保护性免疫 抵抗。我们更普遍的假设是，这对于理解人类疾病是重要的 在没有MyD88的情况下对感染的总体抵抗力。将使用三个具体目标来 了解MyD88-感染期间的独立免疫。目标1：确定T细胞是如何被激活的 弓形虫黏膜反应中MyD88信号的缺失。我们将研究细胞因子 MYD88非依赖的干扰素-γ阳性T细胞的产生条件及表型特征 以及这些细胞的特异性。目的2：确定MyD88缺陷对肠道杀菌效应的影响 功能。我们将研究这个信号转接器的缺陷是如何影响募集和反转录功能的 弓形虫感染后肠粘膜中的微生物效应细胞。目标3：确定如何 弓形虫强毒株免疫小鼠可触发MyD88非依赖性保护性免疫 肠粘膜。我们将使用一种非增殖型弓形虫菌株来确定弓形虫是如何诱导 在一种可无并发症触发免疫的模型中对致命性口服攻击的抵抗力 与寄生虫引起的组织损伤有关。这项研究的重要性在于，它将显著地 扩展和深化我们对免疫诱导和效应机制的理解 MyD88，这对于理解人类的宿主防御是至关重要的。这项研究的最终影响是 它有望识别新的寄生虫和宿主靶标，以促进抗药性和免疫力 在传染病期间。

Project Summary/Abstract The long-term objective of this proposal is to understand induction and effector mechanisms of immunity in the absence of signaling adaptor MyD88. We use as a tool the intracellular protozoan Toxoplasma gondii, an orally acquired opportunistic pathogen that normally induces strong protective Th1- and IFN-γ-based immunity. Toxoplasma can activate mouse immunity through an MyD88-dependent TLR11/12 pathway. Yet, humans lack these TLR and populations deficient in MyD88 expression retain resistance to all but a limited number of bacterial infections. Therefore, immune pathways that do not involve MyD88 are important to understand. We have found that MyD88 knockout mice are capable of generating Th1-like immunity during Toxoplasma infection, indicating that alternative pathways for immune initiation are active in the mouse model. In addition, MyD88 knockout animals can be vaccinated against lethal infection with orally inoculated T. gondii. The cell and molecular mechanisms underpinning MyD88-independent immunity are uncharacterized. The central hypothesis driving this research proposal is that the mouse immune system is equipped to generate protective immunity to Toxoplasma using MyD88-independent pathways of resistance. We more generally hypothesize that this is important for understanding human disease based upon overall resistance to infections in the absence of MyD88. Three Specific Aims will be used to understand MyD88-independent immunity during infection. Aim 1: Determine how T cells are activated in the absence of MyD88 signaling in the mucosal response to Toxoplasma. We will investigate cytokine requirements for MyD88-independent generation of IFN-γ-positive T cells and characterize the phenotype and specificity of these cells. Aim 2: Determine the impact of MyD88 deficiency on gut microbicidal effector functions. We will examine how deficiency in this signaling adaptor affects recruitment and function of anti- microbial effector cells in the intestinal mucosa following Toxoplasma infection. Aim 3: Determine how vaccination with an avirulent Toxoplasma strain triggers MyD88-independent protective immunity in the intestinal mucosa. We will employ a nonproliferating Toxoplasma strain to determine how T. gondii induces resistance to lethal oral challenge in a model where immunity can be triggered without complications associated with parasite-induced tissue damage. The importance of this research is that it will significantly extend and deepen our understanding of induction and effector mechanisms of immunity in the absence of MyD88, which is critical to understanding host defense in humans. The ultimate impact of this research is that it can be expected to identify novel parasite and host targets for promoting resistance and immunity during infectious disease.