Cooperation of CD8+ T cells and phagocytes to eliminate Toxoplasma cysts

CD8 T细胞和吞噬细胞合作消除弓形虫包囊

基本信息

批准号：
8414421
负责人：
YASUHIRO SUZUKI
金额：
$ 34.9万
依托单位：
UNIVERSITY OF KENTUCKY
依托单位国家：
美国
项目类别：
财政年份：
2012
资助国家：
美国
起止时间：
2012-01-01 至 2016-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8414421
关键词：
Acquired Immunodeficiency Syndrome Acute Address Affect Animals Antigens Autophagocytosis Brain CD8-Positive T-Lymphocytes CD8B1 gene Cells Chronic Cyst Cytolysis Cytotoxic T-Lymphocytes Disease Effector Cell Encephalitis Epitopes Excision Genes Goals Histocompatibility Antigens Class I Hybridomas Immune Immune system Immunocompromised Host In Vitro Inbred BALB C Mice Individual Infection Interferons Knockout Mice Life Mediating Mediator of activation protein Methods Microglia Microscopy Molecular Mononuclear Mus Nitric Oxide Parasites Patients Peptides Phagocytes Pharmaceutical Preparations Play Process Production Research Project Grants Resistance Risk Role Staging Surface T-Lymphocyte Tissues Toxoplasma Toxoplasma gondii base cDNA Library cytotoxic human NOS2A protein in vitro Model in vivo killings macrophage novel perforin prevent public health relevance screening two-photon

项目摘要

DESCRIPTION (provided by applicant): Toxoplasma gondii establishes an important chronic infection capable of causing life-threatening toxoplasmic encephalitis in AIDS patients and other immunocompromised individuals. The basis of persistence of the infection is the tissue cyst, which remains largely quiescent for the life of the host, but can reactivate and cause disease. This stage of the parasite is not affected by any of the current drug treatments and it has been generally regarded as untouchable. However, our recent studies revealed that the immune T cells are able to eliminate T. gondii cysts from the brains of infected hosts when the T cells are transferred into infected immunodeficient animals that have already developed large numbers of the cysts. This T cell-mediated immune process is associated with accumulation of mononuclear cells, primarily microglia and macrophages morphologically, around tissue cysts. Since the accumulated phagocytes penetrate within the cyst, these cells appear to be the main effector cells that destroy the cysts and eliminate them from the brain after initiation of this process by immune T cells. CD8+ immune T cells possess a potent activity to initiate this anti-cyst immune process, and the protective activity of the T cells requires perforin. The overall goal of this research project is to determine the molecular mechanisms by which perforin-mediated activity of CD8+ immune T cells cooperates with the phagocytes to remove T. gondii cysts from the brain. In the first aim, we will determine if CD8+ immune T cells accumulate and attach to the cyst-containing cells in the brain. We will also determine if the CD8+ T cells lyse cyst-containing cells in a perforin-dependent manner in vitro and whether the perforin- mediated activity of CD8+ T cells induces the accumulation of phagocytes around the cysts in the brain. In the second aim, we will determine the MHC class I molecule(s) critical for recognition of cyst-containing cells by CD8+ T cells. We will then determine the T. gondii cyst epitope(s) presented by the identified MHC class I molecule for recognition by the CD8+ T cells by screening predicted bradyzoite epitope peptides and/or bradyzoite cDNA library. The third aim is to determine the mechanisms by which phagocytes eliminate T. gondii cysts after initiation of the immune process by CD8+ T cells. We will examine the roles of inducible nitric oxide synthase and autophagy in killing of bradyzoites and elimination of cysts using mice lacking a molecule required for each mechanism. The information generated from the studies in these three specific aims all together will provide the essential basis for developing a novel method(s) to activate CD8+ T cells and phagocytes to eliminate T. gondii cysts that can reactivate and cause toxoplasmic encephalitis.

描述（由申请人提供）：弓形虫是一种重要的慢性感染，能够在艾滋病患者和其他免疫功能低下的个体中引起危及生命的弓形虫脑炎。感染持续存在的基础是组织囊肿，它在宿主的一生中基本上保持静止状态，但可以重新激活并引起疾病。这个阶段的寄生虫不受任何当前药物治疗的影响，并且通常被认为是不可触及的。然而，我们最近的研究表明，当免疫 T 细胞被转移到已经产生大量包囊的受感染免疫缺陷动物体内时，免疫 T 细胞能够消除受感染宿主大脑中的弓形虫包囊。这种 T 细胞介导的免疫过程与组织囊肿周围单核细胞（形态上主要是小胶质细胞和巨噬细胞）的积累有关。由于积累的吞噬细胞渗透到囊肿内，这些细胞似乎是免疫 T 细胞启动这一过程后破坏囊肿并将其从大脑中消除的主要效应细胞。 CD8+免疫T细胞具有启动这种抗囊肿免疫过程的有效活性，并且T细胞的保护活性需要穿孔素。总体目标该研究项目的目的是确定穿孔素介导的 CD8+ 免疫 T 细胞活性与吞噬细胞合作从大脑中清除弓形虫包囊的分子机制。第一个目标是确定 CD8+ 免疫 T 细胞是否积累并附着在大脑中含有囊肿的细胞上。我们还将确定 CD8+ T 细胞是否在体外以穿孔素依赖性方式裂解含有囊肿的细胞，以及穿孔素介导的 CD8+ T 细胞活性是否诱导吞噬细胞在大脑囊肿周围聚集。在第二个目标中，我们将确定对于 CD8+ T 细胞识别包含囊肿的细胞至关重要的 MHC I 类分子。然后，我们将通过筛选预测的缓殖子表位肽和/或缓殖子 cDNA 文库，确定由已识别的 MHC I 类分子呈现的弓形虫包囊表位，以供 CD8+ T 细胞识别。第三个目标是确定吞噬细胞在 CD8+ T 细胞启动免疫过程后消除弓形虫包囊的机制。我们将使用缺乏每种机制所需分子的小鼠来研究诱导型一氧化氮合酶和自噬在杀死缓殖子和消除包囊中的作用。这三个具体目标的研究产生的信息将为开发激活 CD8+ T 细胞和吞噬细胞的新方法提供必要的基础，以消除可重新激活并引起弓形虫脑炎的弓形虫包囊。