Visualization of individual Foxp3+ T cells during an onset and progression of aut

描述(申请人提供)：这项建议的主要目标是确定在什么情况下，在胸腺中避免了负选择的自身反应性T细胞可以击败外周调节的CD4+Foxp3+T细胞。我们认为，为了实现这一目标，有必要研究个体自身反应性和调节性T细胞在其自然环境中的特征。此外，这些细胞必须表达针对自身和非自身抗原的不同抗原受体(TCR)。为此，我们最近建立了一个独特的体内模型，在该模型中，所有T细胞都表达一种多克隆但受限的TCRs(TCRmini小鼠)。在这个模型中，TCRs的CDR3区域可以用来追踪自身免疫性疾病不同阶段的个体NAOVE、效应和调节性T细胞。现在我们还报道，我们已经建立了两个体内模型，在这些模型中，表达这种TCR微型谱系的T细胞会发展成全身或器官特异性的自身免疫。随后，我们的建议将研究抗原特异性自身反应和调节性Foxp3+CD4+T细胞克隆之间的平衡如何被破坏，从而导致自身免疫反应的发生。在特定的目标1中，我们建议确定自然的和适应性的TR细胞在自身免疫性疾病的发生和发展中是否发挥着独特的作用。我们还假设，尽管一些天然的tr细胞表达自身反应性TCRs，并可能失去Foxp3的表达，但这些失能的tr细胞在自然自身免疫反应中的参与并不显著。我们的第二个特定目标将检验自身反应性T细胞的克隆性逃逸是由少数对自身MHC/肽复合体具有较高TCR亲和力的克隆驱动的，还是由自身反应性T细胞频率较高引起的。我们的目标还将是揭示单个自身反应性T细胞克隆是否在其对TR细胞抑制的抵抗力上存在差异。在我们的第三个特定目标中，我们将研究与NAVE Foxp3+细胞相比，抗原经历过的Foxp3+TR细胞是否表现出更好的抑制能力，以及它们的TCR谱系是否比抗原未经历Foxp3+细胞上发现的TCR谱系更具寡克隆性。公共卫生相关性这项建议侧重于研究自然和适应性Foxp3+调节性T淋巴细胞诱导耐受的机制。这些调节性T淋巴细胞监督其他免疫细胞的功能，控制自身反应性T细胞，防止自身免疫的发生。更好地了解自身反应细胞用来超越CD4+Foxp3+细胞调节功能的机制，对于开发更好的治疗自身免疫性疾病的策略至关重要。

DESCRIPTION (provided by applicant): The main goal of this proposal is to determine the circumstances under which autoreactive T cells that have avoided negative selection in the thymus can defeat regulatory CD4+Foxp3+ T cells in the periphery. In our opinion, to achieve this goal it is necessary to study the features of individual autoreactive and regulatory T cells in their natural environment. In addition, these cells must express different antigen receptors (TCRs) specific for both self and non-self antigens. For this purpose, we have recently established a distinctive in vivo model where all T cells express a polyclonal but restricted repertoire of TCRs (TCRmini mice). In this model the CDR3 regions of TCRs can be used to trace individual naove, effector, and regulatory T cells in different stages of autoimmune disease. Now we also report that we have developed two in vivo models where T cells expressing this TCR mini- repertoire develop systemic or organ-specific autoimmunity. Subsequently, our proposal will investigate how the balance between antigen specific autoreactive and regulatory Foxp3+ CD4+ T cells clones can be destroyed, leading to the onset of autoimmune responses. In Specific Aim 1 we propose to determine if natural and adaptive TR cells play a distinctive role during onset and progression of autoimmune disease. We also hypothesize that though some natural TR cells express autoreactive TCRs and may lose Foxp3 expression the participation of these disabled TR cells in natural autoimmune responses is insignificant. Our second Specific Aim will examine if clonal escape of autoreactive T cells is driven by a few clones with higher TCR affinity for self MHC/peptide complexes or is caused by intrinsically higher frequency of autoreactive T cells. Our objective will also be to reveal if individual autoreactive T cell clones differ in their resistance to suppression by TR cells. In our third Specific Aim we will investigate if antigen-experienced Foxp3+ TR cells exhibit improved suppressor ability compared to naove Foxp3+ cells, and whether their TCR repertoire is more oligoclonal than the TCR repertoire found on the antigen-inexperienced Foxp3+ cells. PUBLIC HEALTH RELEVANCE This proposal focuses on investigating the mechanisms of tolerance induction by natural and adaptive Foxp3+ regulatory T lymphocytes. These regulatory T lymphocytes supervise the function of other immune cells and control autoreactive T cells preventing onset of autoimmunity. Better understanding of the mechanisms that autoreactive cells utilize to override regulatory function of CD4+Foxp3+ cells is critical for the development of better therapeutic strategies to treat autoimmune diseases.