SLE患者T淋巴细胞IL-13受体α1基因表达及其调节序列甲基化状态的研究

Expression and methylafion status of IL-13 receptor α1 gene in peripheral T lymphocytes of patients with systemic lupus erythematosus

目的研究SLE患者外周血T淋巴细胞IL-13受体α1（IL-13Rα1）基因mRNA的表达及IL-13Rα1基因调节序列甲基化状态。方法免疫磁珠法（MACS）分离10例SLE患者和6例正常人外周血CD4^＋和CD8^＋T细胞，采用实时荧光定量PCR检测T细胞中IL-13Rα1 mRNA的表达，并用甲基化特异性PCR（MSP）方法检测IL-13Rα1基因调节序列的甲基化水平。结果活动期SLE患者CD4^＋T细胞中IL-13Rα1 mRNA表达水平为2．224±0．251，非活动期SLE患者为1．712±0．132，正常人组为1．104±0．044，三组间比较，差异均有统计学意义（P〈0．05）；CD8^＋T细胞中IL-13Rα1 mRNA表达水平活动期、非活动期及正常人组分别为1．672±0．142，1．410±0．154，1．238±0．106，活动期组与正常人组比较差异有统计学意义（P〈0．05），而非活动期组与正常人组、活动期组与非活动期组比较，差异均无统计学意义（P〉0．05）。CD4^＋T细胞中IL-13Rα1基因甲基化指数活动期SLE患者为0．454±0．023，非活动期为0．635±0．065，正常人为0．844±0．097，三组间比较，差异均有统计学意义（P〈0．05）；CD8^＋T细胞中IL-13Rα1基因甲基化指数三组间比较，差异均无统计学意义（P〉0．05）。SLE患者外周血CD4^＋，CD8^＋T细胞IL-13Rα1 mRNA的表达与疾病活动度（SLEDAI评分）呈正相关（r=0．79，P〈0．01；r=0．76，P〈0．05）；CD4^＋T细胞的IL-13Rα1基因的甲基化水平与疾病活动度（SLEDAI评分）呈负相关（r=-0．89，P〈0．01）；CD4^＋T细胞IL-13Rα1 mRNA表达与其调节序列的甲基化水平呈负相关（r=-0．84，P〈0．01）。结论SLE的发生发展可能与DNA低甲基化导致SLE患者T细胞过度表达IL-13Rα1有关。

Objective To investigate the mRNA expression and methylation status of IL-13 receptor （IL-13R）α1 gene in peripheral T lymphocytes of patients with systemic lupus erythematosus （SLE）. Methods Venous blood samples were obtained from 10 SLE patients （5 in active phase, 5 in inactive phase） and 6 normal human controls. CD4^＋ and CD8^＋ T cells were isolated from these samples via magnetic activated cell sorting （MACS）. Real-time quantitative PCR was used to test the mRNA expression of IL-13Rα1 gene, and methylation specific PCR to detect the methylation status. Results The expression level of IL-13Rα1 mRNA was 2.224±0.251, 1.712±0.132, and 1.104±0.044 in CD4^＋ T cells of active SLE patients, inactive SLE patients and controls, respectively; the difference between the three groups was statistically significant（ all P 〈 0.05 ）. The expression level of IL-13Rα1 mRNA in CD8^＋ T cells was significantly higher in active SLE patients than that in the normal controls （ 1.672±0.142 vs 1.238±0.106, P 〈 0.05）, while no difference was noted between inactive and active SLE patients or normal controls. The methylation index of IL-13Rα1 gene was 0.454±0.023, 0.635±0.065, 0.844±0.097 in CD4^＋ T cells of active SLE patients, inactive SLE patients and normal controls, respectively, and the difference between the three groups was significant （all P 〈 0.05）, while no significant difference was observed in the methylation index in CD8^＋ T cells among these groups （P〉 0.05）. The IL-13Rα1 mRNA expression in CD4^＋ T and CD8^＋ T cells was positively correlated with SLE disease activity index （SLEDAI） score （r = 0.79, 0.76, P = 0.007, 0.02 respectively）. A negative correlation was found between the methylation level of IL-13Rα1 in CD4^＋ T cells and SLEDAI score （r = -0.89, P〈 0.01 ）, as well as between the IL-13Rα1 mRNA expression and its methylation level （r = -0.84, P 〈 0.01 ）. Conclusion The development of SLE may be related to the overexpression of IL-13Rα1 gene induced by DNA hypomethylation in T cells.