IgG型抗双链DNA抗体对体外培养系膜细胞表型转化的影响

Effect of anti--dsDNA antibodies on phenotype transformation of cultured rat glomerular mesangial cells in vitro

目的探讨IgG型抗双链DNA（dsDNA）抗体对正常大鼠系膜细胞表型转化的影响。方法将马疫锥虫动基体DNA以不同途径免疫大鼠，分别诱生IgG型、IgM型抗dsDNA抗体，其血清分别与正常大鼠系膜细胞（MCs）共同培养，同时设立正常血清对照组。采用酶联免疫吸附法（EHSA）与Westem blot法检测MCs表达转化生长因子-β1（TGF-β1）、α-平滑肌肌动蛋白（α-SMA）、层黏连蛋白（LN）等水平，四甲基偶氮唑蓝（MTT）比色法检测MCs的增殖率，锥虫蓝染色法测活细胞比例，透射电镜下观察形态学改变。结果与正常血清组比较，IgM抗体组的上述指标差异无统计学意义（P〉0.05），而IgG抗体组的细胞增殖率与活细胞比例差异无统计学意义（P〉0．05），但其余指标皆上升（P〈0．05）。电镜下IgG抗体组的MCs呈肌成纤维细胞样形态改变，而其余两组大致正常。结论IgG型抗dsDNA抗体可能通过诱导MCs表型转化而参与狼疮肾炎的发病机制。

Objective To study the effect of IgG subtype of anti-double stranded DNA （dsDNA） antibodies on the phenotype transformation of cultured rat glomerular mesangial cells （MCs） in vitro. Methods The purified kinetoplast DNA （kDNA） of Trypanosoma Equiperdum （TE） was injected subcutaneously or intravenously into normal Wistar rats to establish animal models whose sera contained IgG or IgM subtype of anti-dsDNA antibodies. The normal rat MCs were co-cultured in vitro with the experimental models＇ sera respectively. The control group of MCs was co-cultured with normal rat sera. The levels of TGF-β1, α-SMA and laminin expressed by MCs were detected by ELISA and western blotting. Their proliferations were measured by MTI＇ assay. These morphological changes were observed under electronic microscopy. Results Compared with the control group, the group of IgG antibodies showed higher levels of TGF-β1, α-SMA and laminin （P〈0.05） with the exception of proliferation levels of MCs （P〉0.05）. There was no significant difference between these parameters of the two groups of IgM antibodies and normal sera （P〉0.05）. The MCs co-cultured with sera of IgG antibodies showed marked morphological changes including enlongated shape and the appearance of smooth muscle actin, which could not be observed in other groups. Conclusion The IgG subtype of anti-dsDNA antibodies play a role in the pathogenesis of lupus nephritis by inducing phenotype transformation of MCs.