Regulatory cells involved in the suppression of active EAE

为了研究外周髓鞘抗原特异性自身反应性T细胞的抑制机制，我们从MS患者身上分离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。由于传统的髓磷脂抗原特异性TCR Tg小鼠是由脑源性T细胞克隆产生的，因此由脑源性TCR生成的Tg小鼠发生自发或活性EAE。然而，从人身上鉴定出致脑T细胞克隆是不可能的。我们选择了在人体内表达HLA-DRB1*0401的能识别MBP免疫优势表位MBP111-129的T细胞克隆。有趣的是，CD4+CD25- Tg t细胞在体外可分化为Th1细胞，Th1细胞过继转移后可诱导EAE，而MBP111-129/CFA免疫MS2-3C8 TCR Tg小鼠不能诱导EAE。本初步实验提示，在MS2-3C8 TCR Tg小鼠中可产生抑制脑源性T细胞分化的Tregs。我们发现MHC ii类限制性mbp特异性CD8+ Tg T细胞在MS2-3C8 Tg小鼠中与CD4+ Tg T细胞一起发育。CD8+ Tg T细胞具有细胞毒性并产生大量IFN-？MBP111-129/HLA-DRB1*0401复合物的响应，并表现出Tc1表型。我们还发现8-12%的CD4+ Tg na？5个T细胞在MS2-3C8 Tg小鼠中表达CD4+CD25+ Foxp3+表型，这些Tg Tregs抑制CD4+CD25 -Tg T细胞的增殖。这些CD8+ Tg T细胞和CD4+CD25+ Tg T细胞是抑制活性EAE诱导的候选Tregs。在本研究中，我们将鉴定能够抑制活性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的抑制潜力。本研究为进一步了解Tregs及其抑制机制奠定了基础，为NIH RO1的应用奠定了基础。首席研究员/项目主任（后、中、前）：伊藤广一

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