Generation/Maintenance of Type 1 Immunity to Toxoplasma

描述（由申请人提供）：在世界范围内，由专性细胞内寄生虫引起的弓形虫病和其他感染仍然是人类和牲畜发病和死亡的主要原因。ifn - γ是一种由1型淋巴细胞和NK细胞产生的细胞因子。刚地弓形虫感染小鼠是研究1型细胞分化的良好模型，也是评估体内ifn - γ功能的高度严格的测试。该提案将系统地定义细胞间和细胞内信号，这些信号控制ifn - γ介导的反应的迅速启动，维持和成功运作，对宿主生存至关重要。实验方法依赖于正常和缺陷小鼠品系的体内感染和遗传研究，并辅以淋巴细胞功能的体外细胞和分子分析。第一个目标将严格评估淋巴细胞谱系和转录因子对IL-12诱导的、ifn - γ介导的宿主对弓形虫感染的抗性的需求。第二个目的是评估Tbet的作用，Tbet是一种新的Thi特异性转录因子，在维持长期ifn - γ效应功能和免疫保护中的作用。最后的第三个目标将提供详细的表型和遗传分析新发现的缺陷，早期IL-12诱导的ifn - γ反应导致弓形虫感染的急性易感性。这种基因决定的部分lL-12无反应性对ifn - γ产生的关键信号转导和转录因子通路的影响将被评估。在成功和平衡的免疫应答过程中，ifn - γ生成型1淋巴细胞的产生、维持和正常功能受到细胞和分子调控决定因素的影响。由于许多传染性和自身免疫性病理是由1型效应物功能障碍引起的，因此拟议研究提供的见解最终将导致改善对此类疾病状态的管理。这笔拨款还应该为设计免疫策略以诱导持续的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.