REGULATION OF AUTOIMMUNITY WITH T CELL RECEPTOR PEPTIDES

描述（由申请人提供）：T细胞对抗原自身tcr序列的识别构成了一种独特的外周自调节机制，用于限制由Th1细胞介导的针对组织特异性抗原（如髓鞘蛋白）的炎症反应。从我们使用TCR肽为多发性硬化症（MS）患者接种疫苗的临床试验中获得的数据提出了关于TCR特异性T细胞的起源和作用机制的关键问题，这将需要回到动物模型中。具体来说，我们已经观察到tcr反应性T细胞可能获得与CD4+CD25+调节性T细胞（Treg）相关的特性，除了它们之前记录的通过释放IL-10调节Th1细胞的能力之外，具有类似于Th2或Tr1细胞的特性。这些观察结果提出了一个基本问题，即TCR反应性细胞是否代表一种独特的调节谱系，或者携带特异性TCR决定因子的T细胞受体的T细胞是否可以根据其微环境分化为不同类型的调节性或效应性T细胞。这个问题具有重要意义，因为在后一种情况下，自身免疫性疾病过程本身可能指导与健康期间不同的tcr反应性T细胞亚型分布，对调节功能的影响未知。因此，我们提出假设，tcr特异性T细胞代表了一种独特的自身反应性细胞谱系，介导了一系列依赖于胸腺和外周分化途径的调节作用。为了解决这一假设，我们建议：1)确定CD4+ tcr特异性T细胞的发育途径；2)确定tcr反应性T细胞抑制致病性和旁观者T细胞并预防实验性自身免疫性脑脊髓炎（EAE）的调控机制；3)评价HC和MS患者接种前后tcr反应性T细胞谱及其对免疫功能的影响。我们将使用表达HLA-DR2 （MS的已知危险因子）的人源化Tg小鼠，这些小鼠对髓鞘少突胶质细胞糖蛋白(MOG)-35-55肽诱导的EAE高度敏感。此外，为了更有效地追踪致病性T细胞并评估靶向抗TCR反应的诱导作用，我们将利用表达髓鞘碱性蛋白(MBP)-85-99肽的人类TCR特异性的DR2小鼠。这些DR2/TCR+小鼠对MBP-85-99肽诱导的EAE高度敏感，我们进一步提出通过制造DR2/ cita - tg小鼠来模拟人类T细胞自我TCR决定因子的呈现，其中T细胞被编程为过度表达II类分子。在这些小鼠和缺乏Treg相关Foxp3基因的小鼠中进行的研究对于明确确定各种tcr反应亚型保护功能的差异至关重要。然后，动物模型的结果将转化回人类供体，以评估未免疫的HC和接种TCR的MS患者中存在的TCR亚型的分布，以确定与临床益处相关的主要模式。

DESCRIPTION (provided by applicant): T cell recognition of antigenic self-TCR sequences constitutes a distinct peripheral autoregulatory mechanism for limiting inflammatory reactions mediated by Th1 cells directed at tissue-specific antigens such as myelin proteins. Data obtained from our clinical trials using TCR peptides to vaccinate patients with multiple sclerosis (MS) have raised crucial questions regarding the origin and mechanism of action of TCR- specific T cells that will require a return to animal models. Specifically, we have observed that TCR-reactive T cells may acquire properties associated with CD4+CD25+ regulatory T cells (Treg), in addition to their previously documented ability to regulate Th1 cells through the release of IL-10, with properties similar to Th2 or Tr1 cells. These observations raise the fundamental question of whether the TCR-reactive cells represent a single distinct regulatory lineage or whether T cells bearing T cell receptors specific for self TCR determinants can differentiate into different types of regulatory or effector T cells according to their micro- environment. This question has important implications because in the latter case, the autoimmune disease process itself might direct a different distribution of TCR-reactive T cell subtypes than occurs during health, with unknown effects on regulatory function. We thus propose the hypothesis that TCR-specific T cells represent a unique lineage of autoreactive cells that mediate a spectrum of regulatory effects that are dependent on both thymic and peripheral differentiation pathways. To address this hypothesis, we propose to: 1) Determine what are the developmental pathways for CD4+ TCR-specific T cells; 2) Determine what are the governing mechanisms by which TCR-reactive T cells inhibit pathogenic and bystander T cells and prevent experimental autoimmune encephalomyelitis (EAE); and 3) Evaluate the spectrum of TCR-reactive T cell types in HC and in MS patients before and after vaccination and their effects on immune function. We will utilize humanized Tg mice that express HLA-DR2, a known risk factor for MS, that are highly susceptible to EAE induced with myelin oligodendrocyte glycoprotein (MOG)-35-55 peptide. Moreover, in order to more effectively follow pathogenic T cells and evaluate induction of a focused anti-TCR response, we will utilize DR2 mice that also express a human TCR specific for myelin basic protein (MBP)-85-99 peptide. These DR2/TCR+ mice are highly susceptible to EAE induced with the MBP-85-99 peptide, and we further propose to mimic human T cell presentation of self-TCR determinants by producing DR2/CIITA-Tg mice, in which T cells are programmed to over-express class II molecules. Studies in these mice and in mice deficient in the Treg associated Foxp3 gene are crucial for a definitive determination of differences in the protective function of various TCR-reactive subtypes. Results from the animal models will then be translated back to human donors to evaluate the distribution of TCR subtypes present in un-immunized HC and TCR vaccinated MS patients to establish predominant patterns that are associated with clinical benefit.