EAE小鼠胸腺主要凋亡细胞群及其细胞凋亡机制的初步探讨

A preliminary study of the main apoptotic cells in EAE mice thymus and the mechanism of the apoptosis

目的初步探讨实验性自身免疫性脑脊髓炎(EAE)小鼠胸腺主要凋亡细胞群及其胸腺细胞的凋亡机制。方法用MOG35-55/CFA乳化剂背部皮下免疫C57BL/6小鼠,诱导EAE。观察实验动物的临床症状和脊髓病理改变;计数2组小鼠胸腺细胞总数;应用流式细胞仪分析2组小鼠胸腺CD4+CD8+双阳性(DP),CD4+/CD8+单阳性(SP)和CD4+Foxp3+调节性T细胞(Treg)的比例变化。结果 EAE组模型诱导成功,HE染色发现脊髓组织炎症细胞浸润;EAE小鼠发病高峰期胸腺细胞总数和胸腺DP细胞显著低于对照组(P<0.01);SP细胞的比例高于对照组(P<0.05),但是其绝对值低于对照组(P<0.01)。结论 EAE小鼠胸腺细胞的主要凋亡细胞群是CD4+CD8+DP细胞,其可能凋亡机制是通过加速DP细胞向SP细胞的分化,从而加快DP细胞凋亡和SP细胞释放入外周并浸润中枢神经系统。

To investigate the main apoptotic cells in the thymus of experimental autoimmune encephalomyelitis（EAE） mice and the possible mechanism of the apoptosis, EAE models of C57BL/6 mice were established by MOG35-55/CFA emulsion. Clinical symptoms and histopathologic change of spinal cord were observed to evaluate the severity of EAE. The total number of thymocytes in EAE and control groups was counted. And flow cytometry was employed to determine the percentages of CD4＋CD8＋double positive cells（DP）, CD4＋/CD8＋single positive cells（SP） as well as CD4＋Foxp3＋regulatory T cells（Treg） in thymus. Data showed there was a significant decrease in the number of thymocytes and DP cells in EAE group（P〈0.01）. While the percentages of SP cells increased（P〈0.05） in EAE, but the absolute value decreased（P〈0.01）, compared to counterparts. All the result indicated that DP cells are the major apoptotic cells in thymus of EAE mice. The underlying mechanism of thymocyte apoptosis might be that DP cells differentiation into SP cells is accelerated in EAE mice, which leads to accelerated apoptosis of DP cells and quick release of SP cells to the periphery, infiltrating central nervous system.