Regulatory cells involved in the suppression of active EAE

为了研究髓鞘抗原特异性自身反应性T细胞在外周的抑制机制，我们建立了表达髓鞘碱性蛋白(MBP)特异性人T细胞受体(TCR)的转基因(TG)小鼠，该受体是从MS患者中分离出来的。由于传统的髓鞘抗原特异性TCRTG小鼠是由脑源性T细胞克隆产生的，因此由脑源性TCR产生的TG小鼠发生自发性或活动性EAE。然而，不可能从人类中识别出脑源性T细胞克隆。我们选择了识别MBP免疫优势表位MBP111-129的T细胞克隆，用于表达人类的HLADRB1*0401。有趣的是，CD4+CD25-TGT细胞在体外可以分化为Th1细胞，过继转移后Th1细胞可以诱导EAE，而MBP111-129/CFA免疫MS2-3C8 TCR Tg小鼠不能诱导EAE。这一初步实验表明，在MS2-3C8 TCRTG小鼠体内存在能够抑制脑源性T细胞分化的Tregs。我们发现在MS2-3C8 TG小鼠中，MHC II类限制性MBP特异性CD8+TG T细胞与CD4+TG T细胞一起发育。CD8+Tg T细胞具有细胞毒作用，可产生高水平的干扰素？对MBP111-129/HLA-DRB1*0401复合体的反应表现为Tc1表型。我们还发现，在MS2-3C8转基因小鼠中，8-12%的CD_4~+T细胞表达CD_4~+CD25~+Foxp3+表型，这些TG T细胞对CD_4~+CD25-TG T细胞的增殖有抑制作用。CD8+TGT细胞和CD4+CD25+TGT细胞是抑制活动期EAE诱导的候选Tregs。在本研究中，我们将确定能够抑制活动期EAE的调节性T细胞亚群，并研究它们对其他髓鞘抗原PLP和MOG诱导的EAE的抑制作用。这项研究可能有助于更好地理解Tregs及其抑制机制，并为NIH RO1的应用奠定坚实的基础。1名首席调查员/项目主任(最后、第一、中间)：伊藤口一

To study the suppressive mechanism of myelin antigen-specific autoreactive T cells in the periphery, we have generated transgenic (Tg) mice expressing Myelin Basic Protein (MBP)-specific human T cell receptor (TCR) isolated from an MS patient. Since conventional myelin antigen-specific TCR Tg mice were generated from encephalitogenic T cell clones, the Tg mice generated from the encephalitogenic TCR developed spontaneous or active EAE. However, it is impossible to identify encephalitogenic T cell clones from humans. We chose the T cell clone which recognize the immunodominant epitope of MBP, MBP111-129, in humans expressing the HLA-DRB1*0401. Interestingly, CD4+CD25- Tg Tcells can differentiate into Th1 cells in vitro and the Th1 cells induce EAE upon adoptive transfer, while EAE cannot be induced in the MS2-3C8 TCR Tg mice by immunization with MBP111-129/CFA. This preliminary experiment suggests that Tregs capable of suppressing the differentiation of encephalitogenic T cells develop in the MS2-3C8 TCR Tg mice. We found that MHC class II-restricted MBP-specific CD8+ Tg T cells develop together with CD4+ Tg T cells in the MS2-3C8 Tg mice. The CD8+ Tg T cells are cytotoxic and produce a high amount of IFN-? in response to MBP111-129/HLA-DRB1*0401 complexes and exhibit Tc1 phenotype. We also found that 8-12% of CD4+ Tg na?ve T cells express CD4+CD25+ Foxp3+ phenotype in the MS2-3C8 Tg mice and these Tg Tregs suppress the proliferation of CD4+ CD25-Tg T cells. These CD8+ Tg T cells and CD4+CD25+ Tg T cells are candidate Tregs which suppress the induction of active EAE. In this study, we will identify the regulatory T cell subsets which can suppress active EAE and investigate their suppressive potential against EAE induced by other myelin antigens, PLP and MOG. This study could lead to a better understanding of Tregs and their suppressive mechanism and a solid ground for a NIH RO1 application. 1 Principal Investigator/Program Director (Last, First, Middle): Ito, Kouichi