可溶性pMHC二聚体诱导的一群新型调节性T细胞在EAE小鼠体内诱导免疫耐受的研究

Experimental autoimmune encephalomyelitis (EAE) is an autoimmune disease of the CNS mediated by T cells, which serves as a classic animal model of human multiple sclerosis. In the MOG35-55 peptide-induced EAE model in C57BL/6 mice, the T cell epitope is clear and the corresponding auto-reactive CD4+ T cells can be activated and cause tissue damage. In our previous work, we found that the soluble MOG35-55/I-Ab dimer could combine with the MOG35-55 specific TCR with high affinity, abrogate pathogenic T cells in EAE, and induce a group of suppressor cells with a phenotype profile of CD4+CD3lowTCRlowTGF-β+IL-10+, which was speculated as a new regulatory T cell (Treg) subpopulation. In this work, we plan to explore the function and the cellular mechanism of this new Treg subpopulation both in vitro and in vivo. Specifically, these new Treg cells will be transferred into the MOG35-55 peptide-induced EAE model to verify the capabilities to inhibit the auto-reactive T cell response, induce self-tolerance, block the EAE disease and prevent a recurrence when the mice are re-stimulated with the same antigen. This study will establish a culture system to expand the new Treg cells in vitro effectively, and provide direct experimental basis for treating autoimmune disease by these cells.

实验性自身免疫性脑脊髓炎（EAE）是人类多发性硬化的动物模型，是典型的T细胞应答诱导的自身免疫病。在抗原肽MOG35-55诱发的C57BL/6小鼠EAE模型中，T细胞识别表位十分明确，可诱导相应的自身反应性CD4+T细胞应答，造成组织损伤。我们的前期工作显示：可溶性MOG35-55/I-Ab二聚体可与MOG35-55特异性TCR发生高亲和力结合，抑制EAE自身反应性T细胞应答；并诱导出一群表型为CD4+CD3lowTCRlowTGF-β+IL-10+的抑制性细胞，推测为一群新型调节性T细胞（Treg）亚群。本研究拟对这群新型Treg进行体内、外功能及细胞学机制研究。将该新型Treg过继到MOG35-55诱发的EAE模型体内，抑制自身反应性T细胞应答，诱导自身耐受，阻断小鼠EAE的发生、防止相同抗原再次刺激诱导的EAE复发。为体外大量扩增新型Treg用于治疗自身免疫性疾病提供直接的实验依据。

本研究基于申请人博士论文新发现：可溶性MOG35-55/I-Ab二聚体与EAE自身反应性T细胞体外共培养过程中诱导并显著扩增出一群表型为D4+CD3lowTCRlowmTGF-β+IL-10+的细胞群，推测其为一类新型获得性Treg亚群。本研究通过体外功能试验证实了这群细胞能够显著抑制致脑炎性T细胞的增殖、分化，并以一种细胞-细胞接触依赖性地方式发挥抑制功能，抑制功能与其表达的mTGF-β及特异性TCR有关。将这群获得性Treg过继给MOG35-55诱发的EAE小鼠能够显著缓解神经功能症状和中枢神经系统炎症，与可溶性MOG35-55/I-Ab二聚体联合使用时有显著的协同效应。其神经保护作用与抑制自身反应性Th1、Th17分化与浸润，增强TGF-β相关的负调节机制有关。本研究为体外特异性扩增获得性Treg并用于治疗自身免疫性疾病提供直接的体内外实验依据。