Generation/Maintenance of Type 1 Immunity to Toxoplasma

描述(由申请人提供)：在世界范围内，弓形虫病和由专性细胞内寄生虫引起的其他感染仍然是人类和牲畜发病和死亡的主要原因。宿主防御这些病原体的中心媒介是干扰素-伽马，这是一种由1型淋巴细胞和NK细胞产生的细胞因子。弓形虫在小鼠体内的感染是研究1型细胞分化的良好模型，也是评估体内干扰素-γ功能的高度严格的测试。这项建议将系统地定义细胞间和细胞内的信号，这些信号管理着对宿主生存至关重要的干扰素-γ介导的反应的迅速启动、维持和成功发挥作用。实验方法依赖于体内感染和对正常和缺陷小鼠品系的遗传学研究，并辅之以淋巴细胞功能的体外细胞和分子分析。第一个目的是关键地评估淋巴细胞谱系和转录因子对IL-12诱导的、干扰素-γ介导的宿主对弓形虫感染的抵抗力。第二个目的是评估Tbet，一种新的Thi特异性转录因子在维持长期的干扰素-γ效应功能从而免疫保护中的作用。最后的第三个目标将提供对新发现的IL-12诱导的干扰素-伽马反应的早期缺陷的详细表型和遗传分析，该缺陷导致对弓形虫感染的急性易感性。将评估这种遗传决定的、部分IL-12无反应性对信号转导和转录因子(S)途径的影响，这些信号转导和转录因子对干扰素-γ的产生至关重要。建议的实验将为细胞和分子调控决定因素(S)在成功和平衡的免疫反应中影响产生干扰素-γ的1型淋巴细胞的产生、维持和适当的功能提供新的信息。由于许多感染和自身免疫病理是由1型效应器功能障碍引起的，拟议的研究提供的见解最终应该会改善对这种疾病状态的管理。这笔赠款还应为设计免疫战略以诱导持续的1型反应提供见解。

DESCRIPTION (provided by the applicant): Worldwide, toxoplasmosis and other infections caused by obligate intracellular parasitic agents remain a major cause of morbidity and mortality in humans and in livestock. A central mediator of host defense against these agents is IFN-gamma, a cytokine produced by Type 1 lymphocytes and NK cells. Toxoplasma gondii infection in the mouse represents a well-characterized model to study the differentiation of type 1 cells and a highly stringent test to assess IFN-gamma function in vivo. This proposal will systematically define the intercellular and intracellular signals that govern the prompt initiation, maintenance and successful functioning of IFN-gamma-mediated responses critical for host survival. The experimental methods rely on in vivo infection and genetic studies of normal and defective mouse strains aided by ex vivo cellular and molecular analyses of lymphocyte function. The first aim will critically assess the lymphocyte cell lineage and transcription factor requirements for IL-12 induced, IFN-gamma mediated host resistance to T. gondii infection. The second aim evaluates the role of Tbet, a novel Thi -specific transcription factor in sustaining long term IFN-gamma effector function and thus immune protection. A final third aim will provide detailed phenotypic and genetic analyses of a newly discovered defect in early IL-12 induced IFN-gamma responses resulting in acute susceptibility to T. gondii infection. The influence of this genetically dictated, partial lL-12 unresponsiveness on signal transduction and transcription factor(s) pathways critical for IFN-gamma production will be evaluated. The proposed experiments should provide novel information on cellular and molecular regulatory determinant(s) affecting the generation, maintenance and appropriate functioning of IFN-gamma producing type 1 lymphocytes during a successful and balanced immune response. Since many infectious and autoimmune pathologies result from Type 1 effector dysfunction, the insights provided by the proposed studies should eventually result in improved management of such disease states. This grant should also provide insights for designing immunization strategies to induce sustained type 1 responses.