Pathogenic and Protective T cells in Toxoplasmosis

描述(申请人提供)：对弓形虫和许多其他细胞内病原体的成功细胞免疫反应涉及到IL-12和IL-10之间的微妙平衡。IL-12是由寄生虫触发的促炎固有细胞因子，IL-10是适应性T细胞产生的调节细胞因子，用于预防免疫病理。这项建议的总体目标是探索IL-12如何控制保护性免疫所需的寄生虫反应性CD8效应细胞和记忆细胞的产生和持续，以及IL-10如何以一种新的自分泌方式发挥作用，以避免组织损伤。利用T细胞系特异性干扰IL-10信号的新小鼠模型，我们获得了证据表明，在弓形虫感染期间，IL-10激活T细胞固有的抗炎反应是预防发病率和死亡率所必需的。我们将使用这种转基因和其他基因敲除小鼠模型来阐明IL-10在Th1应答弓形虫过程中的动力学、调节和功能后果，并探索IL-10细胞如何自主抑制Th1细胞因子应答的新机制。我们最近描述了弓形虫CPS疫苗株免疫诱导的四种CD8细胞亚群，并发表了证据表明，IL-12是产生表达IFN3、颗粒酶B和KLRG1的效应性CD8T细胞所必需的。与Hidde Ploegh博士在麻省理工学院的实验室合作，我们已经从弓形虫中鉴定出第一个KB限制性CTL表位，我们的合作者还开发了一种克隆小鼠系，该克隆鼠系携带对这种KB限制性弓形虫抗原有反应的CD8T细胞。利用这些新的小鼠和免疫学试剂，我们将阐明弓形虫疫苗接种和感染诱导的异源CD8 T细胞亚群的细胞因子需求、谱系关系和功能意义。我们将严格评估IL-12信号在即刻的成本和收益，并召回CD8保护性反应再次感染。 公共卫生相关性：由寄生原生动物和其他细胞内微生物引起的疾病是全世界死亡和发病的主要原因。发病率和死亡率可能是由于免疫缺陷导致寄生虫对组织的破坏，也可能是由于过度狂热或免疫反应失调造成的。这里提出的研究将为如何抑制潜在的致病Th1细胞以及如何长期产生和维持保护性CD8T细胞提供新的见解，特别是关于细胞因子如何控制这些免疫过程。来自这些调查的见解可能会对疫苗接种战略和炎症性和传染性疾病的管理有用。

DESCRIPTION (provided by applicant): A successful cellular immune response to Toxoplasma gondii and many other intracellular pathogens involves a delicate balance between the actions of IL-12, a pro- inflammatory innate cytokine triggered by the parasite and IL-10, a regulatory cytokine produced by adaptive T cells to prevent immunopathology. The overall goal of this proposal is to explore how IL-12 controls the generation and persistence of parasite- reactive CD8 effector and memory cells required for protective immunity and how IL-10 acts in a novel autocrine fashion to avert tissue damage. Using a new mouse model with T-cell lineage specific interference in IL-10 signaling, we have obtained evidence that IL- 10 activation of a T-cell intrinsic anti-inflammatory response is required to prevent morbidity and mortality during T. gondii infection. We will use this transgenic and other knockout mouse models to elucidate the kinetics, regulation and functional consequences of IL-10 responsiveness during the Th1 response to T. gondii and explore a novel mechanism for how IL-10 cell-autonomously restrains Th1 cytokine responses. We have recently described four subpopulations of CD8 cells induced by immunization with the cps-vaccine strain of T. gondii and have published evidence that IL-12 is critically required for the generation of effector CD8 T cells expressing IFN3, granzyme B and KLRG1. In collaboration with Dr. Hidde Ploegh's laboratory at MIT, we have identified the first Kb-restricted CTL epitope from T. gondii and our collaborators have also developed a cloned mouse line bearing monoclonal naove CD8 T cells reactive to this Kb- restricted T. gondii antigen. Using these new mouse and immunological reagents, we will elucidate the cytokine requirements, lineage relationships and functional significance of the heterogenous CD8 T cell subsets induced by T. gondii vaccination and infection. We will critically assess the costs and benefits of IL-12 signaling on the immediate and recall CD8 protective response to re-infection. PUBLIC HEALTH RELEVANCE: Disease caused by parasitic protozoa and other intracellular microbial agents are major causes of mortality and morbidity worldwide. Morbidity and mortality may be caused by immunodeficiency leading to tissue destruction by the parasites or these may result from an overzealous or dysregulated immune response. The studies proposed here will provide new insights into how potentially pathogenic Th1 cells are restrained and how protective CD8 T cells are generated and maintained over the long term, specifically with respect to how cytokines control these immune processes. Insights from these investigations may become useful for vaccination strategies and the management of inflammatory and infectious diseases.