CD4 T细胞转化的DN T细胞对小鼠EAE发病的预防

Effect of preventive treatment in EAE mouse model transplanted with DN T cells transformed from CD4 T cells

利用CD4 T细胞体外转化获得具有下调免疫作用的双阴性T细胞(DN T细胞),利用DN T细胞预防性治疗常规变态反应性脑脊髓炎(EAE)小鼠(Mus musculus)模型.观察EAE造模组和DN T细胞预防治疗组两组小鼠EAE评分、体重、关键淋巴细胞因子、组织切片的区别,探索DN T淋巴细胞发挥功能的可能机制.首先诱导获得了抗原特异性的DN T细胞;其次发现一次DN T淋巴细胞的过继输注可以显著降低EAE造模的发病程度,缓解小鼠因为EAE发病而造成的体重减轻;同时和造模组相比,DN T细胞预防组脑部组织淋巴细胞浸润略有减轻,血浆中IL-2和IL-4的分泌也有一定程度的降低;最后通过CFSE增殖实验证实DN T细胞可以显著抑制EAE模型中致炎CD4 T细胞的增殖.本研究证实体外转化的DN T细胞可以减轻EAE模型的发病程度,这种预防作用与DN T淋巴细胞可以抑制致炎CD4 T淋巴细胞的增殖相关.

Multiple sclerosis（MS） is an immune-mediated demyelinating disease of the central nervous system（CNS）. Experimental autoimmune encephalomyelitis（EAE） has long served as an animal model for human MS. Both diseases are characterized by inflammation and demyelination of the CNS. Lots of study confirmed that Th1 and Th17 cells could aggravate the illness, while Foxp3～＋ regulatory T cells（Treg cells） could inhibit the autoimmune reaction and limit disease progression. However, it has been studied that both the number and immune suppression function of Treg cells were reduced in EAE mice, and although myelin specific Treg cells accumulated in the CNS, it failed to control autoimmune inflammation. Based on that, promoting immune regulation by other regulatory cells may be a new strategy to restore immune homeostasis and control EAE. Many studies have demonstrated that in peripheral lymphoid tissues of normal mice and healthy humans, 1% to 3% of T cell receptor positive T cells are double negative T cells（DN T cells）, which capable of down regulating immune responses. We have identified a new differentiation pathway for the conversion of CD4 T cells to DN T cells, which could large amount DN T cells in vitro in a short time. We have showed that the converted DN T cells retained a stable phenotype and expressed a unique set of cell surface markers and gene profiles. These cells were highly potent in suppressing allo-and auto-immune responses both in vitro and in vivo in an antigen specific manner. Adoptive cell therapy using these antigen specific DN T cells could prevent and cure autoimmune diabetes and promote islet allograft survival in NOD mice. In a Con A mediated liver injury model, CD4 T cell converted DN T cells exerted significant protection against immune mediated liver injury and maintained the homeostasis of the immune system. Up to now, there is no report on the role of these converted DNT cells in mouse EAE model. In this study, we further explored the protection and its mechanism of DN T cells on EAE. CD4 T cells were converted to antigen specific DN T cells in vitro with MOG35–55 stimulation. Then we adoptive transferred these antigen specific DN T cells to mice before EAE immunization. Time of disease onset, EAE score, mouse weight, lymphocyte infiltration were compared between EAE control group and DNT pre-treatment group, the inhibitory function of DN T cells on pathogenic CD4 T cells from EAE model were further explored. Our data showed that a single adoptive transfer of MOG35–55 primed DN T cells significantly lowered the EAE score, prevented the weight loss and reduced lymphocytes infiltration in brain tissue. DN T cells pre-treatment group contained lower plasma IL-2 and IL-4 levels compared to EAE control group. In vitro suppression assays showed DN T cells significantly suppressed the proliferation of inflammatory CD4 T cells from EAE mice. Our data suggests that DN T cells can significantly reduce the EAE severity. This preventive effect is partly due to DN T cells＇ suppression on the proliferation and cytokine production of inflammatory CD4 T cells. DN T cells may have a potential clinical application in the prevention and treatment of MS.