自身免疫调节因子对EAMG模型小鼠发病的影响

Effects of autoimmune regulator factors on the pathogenesis of experimental autoimmune myasthenia gravis mice

目的探讨自身免疫调节因子(autoimmune regulator,AIRE)在实验性自身免疫性重症肌无力(experimental autoimmune myasthenia gravis,EAMG)模型小鼠发病中的作用。方法采用亲和层析法从电鳐电器官中提取和纯化乙酰胆碱受体(acetylcholine receptor,AChR),并用其免疫C57BL/6小鼠,根据临床症状及重复电刺激试验结果将造模小鼠分为成模组及未成模组,检测各组小鼠胸腺内AIRE mRNA、AChRα1mRNA表达水平以及CD4+CD25+调节性T细胞(Treg)比例和胸腺细胞增殖能力,并与未成模组、福氏佐剂对照组及健康对照组进行比较。结果与未成模组、福氏佐剂对照组及健康对照组相比,成模组小鼠胸腺内AChRα1亚基基因表达水平减少(P<0.01),胸腺内AIRE mRNA表达水平明显下降(P<0.01),胸腺内CD4+T细胞水平无统计学变化(P>0.05),而胸腺内Treg与CD4+T细胞水平的比例却明显下降(P<0.01),胸腺细胞对刀豆球蛋白A(ConA)刺激的增殖能力增强(P<0.01)。结论 EAMG小鼠模型存在中枢耐受缺陷,AIRE基因通过调节胸腺异位基因的表达和Treg细胞比例而在EAMG的发病中起作用。

Objective To study the effects of autoimmune regulator factors on the mechanisms of central tolerance disorder in experimental autoimmune myasthenia gravis （EAMG） mice. Methods Acetylcholine receptor （AChR） was purified from the electric organs of Torpedo by affinity chromatography, and was used to immunize C57BL/6 mice. The mice were divided into myasthenia gravis （MG） symptom group and non MG symptom group by clinical manifestation and repetitive nerve stimulation. The level of CD4＋ CD25＋ Treg in thymus, non-specific proliferation of thymoeytes stimulated with concanavalin A （ConA）, mRNA expression of self-antigen AChR al subunit and autoimmune regulator （AIRE） in the thymus of EAMG mice were tested and compared with those of other groups. Results Compared with non MG symptom group, CFA group and control group, the level of CD4＋T cells in thymus of MG symptom group was not changed （P〈0.05）, while the level of CD4＋ CD25＋ thymocytes in CD4＋ cells decreased distinctly （P〈O. 01）. In the MG symptom group, the proliferation of thymocytes stimulated with ConA increased significantly, the mRNA expression of AChR al subunit and AIRE in thymus decreased dramatically （all P〈0.01）. Conclusions EAMO mice are deficient in central tolerance, which is related with the development of MG. The blockade of thymic selection of autoreactive T cells and CD4＋ CD25＋ Treg is caused by the diminished expression of self-antigen in thymus of EAMG mice. It also was the potential cause for the deficiency of central and peripheral tolerance. The decreased expression of AIRE in thymus of EAMG mice is the potential cause for the lower expression of self-antigen in thymus.