MRL/lpr小鼠B淋巴细胞活化的免疫病理特征

Immunopathological characteristics of B lymphocyte activation in MRL/lpr mice

目的研究MRL/lpr狼疮样小鼠B淋巴细胞活化的免疫病理学改变。方法20周龄雌性MRL/lpr小鼠取血后脱臼处死,称量胸腺、脾脏重量,计算胸腺指数和脾脏指数;流式细胞术检测小鼠脾淋巴细胞悬液T淋巴细胞亚群、总B细胞和浆细胞比例;HE染色观察小鼠肾脏和脾脏病理;免疫荧光法检测肾脏免疫复合物C3表达;q-PCR检测小鼠脾脏中白细胞介素-21(IL-21)水平;ELISA检测小鼠血清IgG1、IgG2a、抗核抗体(ANA)、抗双链DNA抗体(anti-dsDNA)、B淋巴细胞刺激因子(BLyS)及IL-10水平,另取雌性20周龄BALB/c小鼠作为对照组。结果与对照组相比,MRL/lpr小鼠脾脏指数与胸腺指数均升高;滤泡辅助T淋巴细胞(TFH细胞)、Th17细胞、活化T细胞和浆细胞比例增加,总B细胞和幼稚T细胞比例降低,差异均有统计学意义;模型小鼠肾脏呈现出间质性肾炎特征,C3免疫复合物沉积增加,脾脏中央动脉管壁纤维性增厚,白髓弥漫性增生;模型小鼠血清IgG1、IgG2a、anti-dsDNA、ANA、BLyS、IL-10水平以及脾脏IL-21 mRNA表达水平均升高,差异有统计学意义。结论MRL/lpr模型小鼠脾脏淋巴细胞大量增生,B淋巴细胞高度活化并产生大量自身抗体,肾脏免疫复合物大量沉积呈现间质性肾炎特征,与B细胞活化相关的BLyS、IL-10、IL-21等细胞因子水平也升高。

Absteact Objective To investigate the immunopathological changes of B lymphocyte activation in MRL/lpr lupus-like mice.Methods 20-week-old female MRL/lpr mice were sacrificed by cervical dislocation. The index of thymus and spleen of mice were calculated. The ratio of T lymphocyte subsets, total B cells and plasma cells in spleen lymphocyte suspension were analyzed with flow cytometry. Kidney and spleen pathology were observed with HE staining. The level of immune complex C3 expression in kidney and IL-21 mRNA in spleen were detected by immunofluorescence and q-PCR respectively. Serum IgG1, IgG2 a, ANA, anti-dsDNA, B lymphocyte stimulating factor(BLyS) and IL-10 levels were examinated by ELISA kits. The 20-week-age female BALB/c mice were used as control.Results Compared with the control group, the spleen and thymus index of MRL/lpr mice increased significantly, the proportion of TFH cells, Th17 cells, activated T cells and plasma cells increased while total B cells and immature T cells decreased obviously, and the differences were statistically significant. Furthermore, the C3 immune complex in glomerulus in kidney and the levels of serum IgG1, IgG2 a, anti-dsDNA, ANA, BLyS and IL-10 in MRL/lpr mice increased remarkably, displaying an interstitial nephritis. The spleen HE staining result of model mice displayed diffuse proliferation of white pulp, and the expression of IL-21 in spleen distinctly increased. The differences were statistically significant.Conclusion Similar with SLE, MRL/lpr mice display distinct interstitial nephritis which includes B lymphocyte hyperactivation, a mass of autoantibodies, immune complex deposition and high levels of BLyS, IL-10, IL-21.