T Cell Tolerance & Autoimmunity to Nuclear Antigen La

T细胞耐受性

• 批准号: 8076425
• 负责人: A Darise Farris
• 金额: $ 28.24万
• 依托单位: OKLAHOMA MEDICAL RESEARCH FOUNDATION
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-05-22 至 2013-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8076425
• 关键词: Address; Adopted; Adoptive Transfer; Affect; Antigen Presentation; Antigen-Antibody Complex; Antigen-Presenting Cells; Antigens; Autoantigens; Autoimmune Diseases; Autoimmune Process; Autoimmunity; Automobile Driving; B-Lymphocytes; Biological Models; CD4 Positive T Lymphocytes; Cell Differentiation process; Cells; Chromosomal translocation; Chronic; Cues; Dendritic Cells; Development; Disease; Disease susceptibility; Effector Cell; Elements; Genes; Haplotypes; Health; Helper-Inducer T-Lymphocyte; Hematopoietic; Human; Immune Tolerance; Immune system; Infection; Inflammation; Inflammatory; Interferons; Interleukin-6; Ligands; Lupus; Lymphoid; MHC Class II Genes; Mediating; Modeling; Mus; Nuclear Antigens; Nucleic Acid Binding; Organ; Pathway interactions; Peripheral; Phenotype; Physiological; Predisposition; RNA; RNA Binding; Regulatory T-Lymphocyte; Relative (related person); Role; Self Tolerance; Sjogren' s Syndrome; Structure of germinal center of lymph node; Syndrome; System; Systemic Lupus Erythematosus; T-Cell Receptor; T-Lymphocyte; Toll-like receptors; Transgenic Mice; Transgenic Organisms; cell type; clinically relevant; design; disease phenotype; human TLR7 protein; in vivo; lupus-like; male; novel; overexpression; peripheral tolerance; systemic autoimmune disease

DESCRIPTION (provided by applicant): RNA-binding nuclear antigens are a major class of autoantigen targeted in systemic autoimmune diseases, including systemic lupus erythematosus (SLE) and Sjvgren's syndrome (SS). The mechanisms that normally mediate immunologic tolerance to RNA-binding nuclear antigens and the specific tolerance pathways that are breached in the setting of systemic autoimmunity are not well understood, although it is known that T helper (Th) cells are crucial for disease in murine lupus models. We have developed the first and only mouse transgenic for an RNA-binding nuclear antigen-specific TCR T cell receptor (TCR) in order to delineate specific mechanisms leading to T cell tolerance. By transferring T cells specific for the clinically relevant human La/SS- B antigen (hLa) into mice transgenic for physiologic expression of hLa and tracking their numbers, phenotype and function, we will delineate the mechanisms leading to peripheral T cell tolerance (Aim 1). Preliminary studies have shown that the mode of tolerance adopted by these T cells depends on the level of antigen presentation in the recipients and that the in vivo cues promoting Foxp3+ regulatory T cells in this system differ from those previously described. Analysis of antigen presenting cell (APC) and T cell phenotypes in mice mildly (2X) over-expressing RNA-binding Toll-like receptor 7 (TLR7) in the absence of other lupus susceptibility loci suggest that one cue could be constitutive stimulation of nucleic acid-binding TLR. This hypothesis and its mechanism will be investigated in Aim 1. Mice that over-express TLR7 2X in the absence of other lupus susceptibility loci are healthy and harbor tolerant T cells, whereas mice that over-express TLR7 >4X above normal develop severe, fatal lupus that is T cell dependent. The precise peripheral tolerance mechanisms that are abrogated in CD4+ anti-hLa specific T cells following their transfer into hLa transgenic mice that express TLR7 >4X and their subsequent differentiation into distinct Th and T effector cell phenotypes will be evaluated in Aim 2. We will also determine whether these fates associate with the loss of particular tolerance mechanisms such as deletion and Foxp3+ Treg conversion, and determine the roles of IL-6 and IL-21 in promoting pathogenic Th cell differentiation in this model. Very few studies exist that have investigated the role of in vivo DC in promoting CD4+ T cell tolerance in the steady state, and no such studies for nucleic acid- binding nuclear antigens have been described. In Aim 3, we will determine whether B cells, conventional dendritic cells (DC) or plasmacytoid DC, are essential for promoting the peripheral tolerance of CD4+ T cells specific for this representative RNA-binding nuclear antigen by following the numbers, phenotype and function of anti-hLa-specific T cells in hLa transgenic mice that have been selectively depleted of these cell types. Conversely, we will determine the relative importance of B cells and DC in promoting loss of tolerance and differentiation of anti-hLa specific T cells into pathogenic Th and T effector cell types in the setting of pathogenic (>4X) TLR7 expression. These studies will define the mechanisms of CD4+ T cell tolerance and its loss for a major class of antigen that is targeted in systemic autoimmune disease. PUBLIC HEALTH RELEVANCE Systemic lupus erythematosus (SLE) and Sjogren's syndrome (SS) are chronic, debilitating autoimmune diseases that affect the immune system. The immune systems of humans and mice have natural mechanisms designed to maintain self-tolerance and respond to infection and inflammation. We seek to understand how these elements control CD4+ T cell fate and phenotype under both steady-state and inflammatory conditions so that we can better understand the development of autoimmune disease.

描述(由申请人提供)：RNA结合核抗原是一类主要的自身抗原，用于系统性自身免疫性疾病，包括系统性红斑狼疮(SLE)和干燥综合征(SS)。虽然T辅助细胞(Th)在小鼠狼疮模型中是疾病的关键，但通常介导对RNA结合的核抗原的免疫耐受的机制和在系统性自身免疫背景下被破坏的特定耐受途径尚不清楚。为了阐明导致T细胞耐受的特定机制，我们开发了第一个也是唯一一个通过RNA结合的核抗原特异性TCR T细胞受体(TCR)的小鼠转基因。通过将临床相关的人类La/SS-B抗原(HL A)特异性T细胞转移到转HL A生理性表达的小鼠体内，并追踪其数量、表型和功能，我们将阐明导致外周T细胞耐受的机制(目标1)。初步研究表明，这些T细胞采取的耐受模式取决于受体的抗原提呈水平，并且在这个系统中促进Foxp3+调节性T细胞的体内信号与前面描述的不同。在没有其他狼疮易感基因的情况下，对轻度(2X)过表达RNA结合的Toll样受体7(TLR7)的小鼠的抗原提呈细胞(APC)和T细胞表型的分析表明，一个线索可能是核酸结合TLR的结构性刺激。这一假设及其机制将在目标1中进行研究。在没有其他狼疮易感基因的情况下过度表达TLR7 2X的小鼠是健康的，并拥有耐受性T细胞，而过度表达TLR7和GT；4X的小鼠则会发展成严重的、致命的T细胞依赖的狼疮。在目标2中，我们将评估CD4+抗Hla特异性T细胞转移到表达TLR7和GT；4X的转基因小鼠以及随后分化为不同的Th和T效应细胞表型后被取消的确切的外周耐受机制。我们还将确定这些命运是否与丢失特定的耐受机制(如缺失和Foxp3+Treg转换)有关，并确定IL-6和IL-21在促进致病Th细胞分化中的作用。很少有研究研究体内DC在稳定状态下促进CD4+T细胞耐受的作用，还没有关于核酸结合核抗原的研究。在目标3中，我们将通过跟踪选择性去除这些细胞类型的抗Hla转基因小鼠中抗Hla特异性T细胞的数量、表型和功能，来确定B细胞、常规树突状细胞(DC)或浆细胞样树突状细胞(DC)是否是促进针对这种典型的RNA结合核抗原的CD4+T细胞的外周耐受所必需的。相反，我们将确定在致病性(&gt；4X)TLR7表达的背景下，B细胞和DC在促进抗Hla特异性T细胞丧失耐受性和分化为致病性Th和T效应细胞类型方面的相对重要性。这些研究将确定CD4+T细胞耐受的机制，以及它对系统性自身免疫性疾病靶向的一种主要抗原的丧失。公共卫生相关性系统性红斑狼疮(SLE)和干燥综合征(SS)是影响免疫系统的慢性、衰弱的自身免疫性疾病。人类和小鼠的免疫系统具有天然的机制，旨在保持自身耐受性，并对感染和炎症做出反应。我们试图了解这些因素如何在稳态和炎症条件下控制CD4+T细胞的命运和表型，以便我们能够更好地了解自身免疫性疾病的发展。