CD137 signals in DC during Ag-priming induces tolerance

Ag 启动过程中 DC 中的 CD137 信号诱导耐受

• 批准号: 7582376
• 负责人: ROBERT S MITTLER
• 金额: $ 39.3万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-05-01 至 2010-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7582376
• 关键词: Acute; Adoptive Cell Transfers; Affect; Antibodies; Antibody Formation; Antigens; Apoptosis; Apoptotic; B-Lymphocytes; Bone Marrow; C57BL/6 Mouse; CD4 Positive T Lymphocytes; CD8B1 gene; CHEK2 gene; CTL assay; Cell Death; Cell Survival; Cells; Cellular Immunity; Cessation of life; Cytotoxic T-Lymphocytes; Data; Dendritic Cells; Development; Doctor of Philosophy; Epitopes; Event; Experimental Models; Failure; Feedback; Frequencies; Generations; Hour; Humoral Immunities; Immune; Immune response; Immune system; Immunity; Immunosuppression; In Vitro; Infection; Lead; Lymphocytic choriomeningitis virus; MHC Class I Genes; Measures; Mediating; Memory; Molecular; Mus; Natural Killer Cells; Peripheral; Phenotype; Plant Roots; Population; Production; Rattus; Research Personnel; Signal Transduction; Spleen; Staging; Staining method; Stains; System; T memory cell; T-Cell Activation; T-Cell Proliferation; T-Lymphocyte; TNFRSF6 gene; Testing; Time; Transgenes; Tumor Necrosis Factor Receptor; Vaccinia virus; Vesicular stomatitis Indiana virus; Viral; Viremia; Virus; Virus Diseases; anergy; cellular targeting; clay; cytokine; cytotoxic; design; in vivo; influenzavirus; killings; member; programs; receptor; research study; response; vaccine development

DESCRIPTION (provided by applicant): CD 137 (4-1BB), an activation inducible T cell costimulatory receptor and member of the TNFR superfamily is expressed on activated T cells and NK cells. We have shown that a population of immature dendritic cells in the spleen, and bone marrow derived DC constitutively express CD137. In vivo, anti-CD 137-mediated costimulation markedly enhances CD8 T cell proliferation, effector function, T cell survival, and memory development. However, anti-CD 137 mAbs can suppress T-dependent humoral immunity and induce T helper anergy. This application is designed to define the conditions that lead to T cell activation versus T cell anergy, and to understand the mechanisms that drive these responses. We chose acute LCMV viral infection in C57BL/6 mice as an experimental model because it allowed the concomitant study of T cell and B cell immune responses in a single experimental system. Preliminary data described herein show that anti-CD 137 mAbs can suppress the development of all aspects of anti-LCMV immunity providing the antibody is given within 36 hours of infection. Under these conditions LCMV-infected mice developed viremia, failed to generate virus specific CTL, remained persistently infected, and produced diminished levels of T-dependent antibodies to the virus. Nevertheless, tetramer positive CD8 T cells specific for Gp33-41 or Np396-404 although nonfunctional, were detectable at frequencies well above background in the tolerant mice 100 days post-infection. Similar results were obtained with a VSV epitope expressing vaccinia virus and influenza virus (data not shown). Thus, CD8 T cell responses like CD4 T cell responses can be suppressed by anti-CD 137 mAbs but the timing of mAb administration is critical. These observations have important implications with respect to vaccine development and APC as they prepare to antigen prime T cells. Important to the interpretation of this data is the fact that induction of suppression does not occur in CD137 deficient mice into which wild type T cells are adoptively transferred. Furthermore, CD137 expression on T cells from LCMV infected mice is not apparent by real time PCR or FACS phenotyping until 72 hours post-infection. Mice injected with anti-CD137 after T cell priming has been completed more often than not develop enhanced anti-viral immunity. We provide evidence herein that anti-CD 137 mAbs exert their affect immunosuppressive effect only during antigen priming of T cells, and that the primary cellular target of anti-CD137 mAbs are not T cells, but more likely, CD137 DC. In this proposal, we wish to: (1) Determine die fate and function of immature dendritic cells following anti-CD 137-induced peripheral T cell suppression. (2) Assess whether anti-CD 137-mediated signaling in DC directly aborts immune responses by T cells, induces the generation of cytotoxic DC, Treg, or CTL. (3) Mechanistically determine how antigen-specific CD8 T cells undergo deletion in LCMV infected, anti-CD 137 treated mice. (4) Determine whether CD 137 expression on dendritic cells serves as a molecular switch for suppressing ongoing immune responses. The central hypothesis of this proposal is that CD 137 mediated signaling within the immune system can lead to enhanced T cell immunity and the establishment of T cell memory, or antigen specific T cell suppression. The decision to induce T cell activation versus suppression can be determined by the timing of CD137 signal conveyance, and the cellular target of these signals. Thus, CD 137-mediated signaling in dendritic cells suppresses T cell-mediated immunity and in LCMV infection leads T cell tolerance. In contrast, CD137 signals delivered to T cells amplifies or prolongs T cell immune responses and enhances CD8 T cell survival.

描述（由申请人提供）：CD 137（4-1BB）是一种活化诱导型T细胞共刺激受体，也是TNFR超家族成员，在活化的T细胞和NK细胞上表达。我们已经表明，脾脏中的未成熟树突状细胞群和骨髓来源的DC组成型表达CD 137。在体内，抗CD 137介导的共刺激显著增强CD 8 T细胞增殖、效应子功能、T细胞存活和记忆发育。然而，抗CD 137 mAb可抑制T依赖性体液免疫并诱导T辅助细胞无反应性。该应用程序旨在定义导致T细胞活化与T细胞无反应性的条件，并了解驱动这些反应的机制。我们选择C57 BL/6小鼠急性LCMV病毒感染作为实验模型，因为它允许在单个实验系统中同时研究T细胞和B细胞免疫应答。本文所述的初步数据显示，只要在感染的36小时内给予抗体，抗CD 137 mAb可以抑制抗LCMV免疫的所有方面的发展。在这些条件下，LCMV感染的小鼠出现病毒血症，不能产生病毒特异性CTL，持续感染，并产生减少水平的T依赖性抗体的病毒。然而，在感染后100天，在耐受小鼠中，对Gp 33 -41或Np 396 -404特异性的四聚体阳性CD 8 T细胞尽管无功能，但在远高于背景的频率下可检测到。用表达VSV表位的牛痘病毒和流感病毒获得了类似的结果（数据未显示）。因此，CD 8 T细胞应答（如CD 4 T细胞应答）可被抗CD 137 mAb抑制，但mAb给药的时机至关重要。这些观察结果对于疫苗开发和APC具有重要意义，因为它们准备抗原引发T细胞。对解释该数据重要的是，在野生型T细胞过继转移的CD 137缺陷小鼠中不发生抑制诱导。此外，通过真实的时间PCR或FACS表型分析，直到感染后72小时，来自LCMV感染小鼠的T细胞上的CD 137表达才明显。在T细胞引发完成后注射抗CD 137的小鼠通常会产生增强的抗病毒免疫力。我们在本文中提供的证据表明，抗CD 137 mAb仅在T细胞的抗原引发期间发挥其有效的免疫抑制作用，并且抗CD 137 mAb的主要细胞靶标不是T细胞，而更可能是CD 137 DC。在本研究中，我们希望：（1）确定抗CD 137诱导的外周血T细胞抑制后未成熟树突状细胞的死亡命运和功能。(2)评估DC中抗CD 137介导的信号传导是否直接中止T细胞的免疫应答，诱导细胞毒性DC、Treg或CTL的产生。(3)机械地确定抗原特异性CD 8 T细胞如何在LCMV感染的、抗CD 137处理的小鼠中经历缺失。(4)确定树突状细胞上的CD 137表达是否作为抑制正在进行的免疫应答的分子开关。该提议的中心假设是免疫系统内的CD 137介导的信号传导可导致增强的T细胞免疫和T细胞记忆的建立或抗原特异性T细胞抑制。诱导T细胞活化与抑制的决定可以通过CD 137信号传递的时机和这些信号的细胞靶点来确定。因此，树突状细胞中CD 137介导的信号传导抑制T细胞介导的免疫，并且在LCMV感染中导致T细胞耐受。相反，递送至T细胞的CD 137信号放大或抑制T细胞免疫应答并增强CD 8 T细胞存活。