髓系来源的Gr-1^+CD11b^+抑制细胞参与实验性自身免疫性脑脊髓炎的免疫调节

Myeloid-derived Gr-1^+CD11b^+ suppressor cells are involved in immunoregulation of experimental autoimmune encephalomyelitis

目的探讨Gr-1+CD11b+髓系来源的抑制细胞(MDSC)在实验性自身免疫性脑脊髓炎(EAE)中的数量变化及功能。方法 30只健康雌性C57BL/6小鼠随机分为EAE诱导组和对照组,借助MOG35-55多肽免疫诱导制备EAE小鼠模型,采用HE染色和Luxol快蓝染色评估发病动物的脊髓病理变化。流式细胞分析和免疫荧光染色技术确定2组小鼠脾脏和脊髓组织中Gr-1+CD11b+MDSC的数量变化,体外细胞共培养检测来自EAE小鼠的Gr-1+CD11b+MDSC对CD4+T细胞及CD8+T细胞体外增殖能力的影响。结果 EAE造模成功率为80%(12/15),HE染色显示炎症细胞广泛浸润于EAE小鼠脊髓组织,Luxol快蓝染色在炎性浸润灶内发现多处脱髓鞘区域。EAE诱导组小鼠脊髓组织切片中可见大量Gr-1+CD11b+MDSC,而对照组未发现任何阳性细胞。EAE小鼠的脾质量显著大于对照组[(146.5±12.4)mg vs(67.2±8.7)mg,P<0.01],其中Gr-1+CD11b+MDSC比率明显增高(P<0.01)。与免疫荧光染色结果一致,流式细胞术分析在EAE小鼠脊髓中亦可见明显增多的Gr-1+CD11b+MDSC。体外细胞共培养实验显示,EAE小鼠脊髓中Gr-1+CD11b+MDSC可显著抑制CD4+T细胞和CD8+T细胞的分裂增殖。结论EAE诱导了Gr-1+CD11b+MDSC在脾脏和脊髓中的扩增和聚集,后者参与了EAE疾病的免疫调节过程。

Objective To explore the change in the number and role of Gr-1＋CD11b＋ myeloid-derived suppressor cells （MDSCs） in experimental autoimmune encephalomyelitis （EAE）. Methods Totally 30 healthy female C57BL/6 mice were randomly divided into two groups： EAE-induced group （n = 15） and control group （n = 15）. EAE was induced by immunization with myelin oligodendrocyte glycoprotein peptide 35-55 （ MOG35-55）, and pathological changes in spinal cords were revealed by HE staining and Luxol fast blue （LFB） staining. The number of Gr-1＋CD11b＋ MDSCs in spleens and spinal cords of the two groups was respectively compared by flow cytometry and immunofluorescent staining. The effect of Gr-1＋CD11b＋ MDSCs from EAE mice on the proliferation of CD4＋ T cells and CD8 ＋ T cells was evaluated by in vitro co-culture system. Results Twelve of 15 immunized mice （80%） developed EAE. HE staining showed an extensive infiltration of inflammatory cells in the spinal cords of the EAE mice. LFB staining revealed multiple demyelinated lesions in the above inflammatory infiltration. The immunofluorescent histochemistry suggested that many Gr-1＋CD11b＋ MDSCs were present in spinal cords of the EAE mice, but no positive cells were observed in the control group. The mass of spleen in the EAE mice was significantly higher than that of the control mice [ （146.5±12.4） mg vs （67.2 ±8.7） rng, P〈0.01], and the proportion of splenic Gr-1＋CD11b＋ MDSCs in EAE mice significantly increased （ P〈0.01 vs controls）. Consistent with the results of immunofluorescent staining, a significantly increased proportion of Gr-1＋CD11b＋ MDSCs in spinal cords of EAE mice was observed with flow cytometry. In vitro co-culture analysis revealed that Gr-1＋CD11b＋ MDSCs from spinal cords of the EAE mice markedly suppressed the proliferation of CD4＋ T cells and CD8＋ T cells. Conclusion EAE induces an expansion and aggregation of Gr-1＋CD11b＋ MDSC, s in spleens and spinal cords. These cells suppress T cell proliferation in vitro and are involved in the immunoregulation of EAE.