Mi Xiang-bin, Zeng Fan-qin
Department of Dermatology, Second Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China.
Acta Pharmacol Sin. 2008 Jan;29(1):105-12. doi: 10.1111/j.1745-7254.2008.00739.x.
DNA methylation regulates gene expression, and hypomethylation is associated with abnormal T-cell function in systemic lupus erythematosus (SLE). However, little is known about the methylation levels of the interleukin (IL)-4 and -6 promoters in SLE patients.
T cells were isolated from 20 SLE patients and 10 healthy controls, activated in vitro in the presence or absence of 5- azacytidine (5-azaC), and their IL-4 and -6 transcripts were characterized using semiquantitative RT-PCR. Following bisulfate modification of their genomic DNA, the levels of DNA methylation in the IL-4 or -6 promoter were determined by nested PCR and direct sequencing.
The levels of IL-4 and -6 mRNA transcripts were significantly higher in SLE T cells, as compared with that in the controls. Furthermore, the treatment of healthy T cells with 5-azaC demethylated the CpG islands in the IL-4 or -6 promoter and increased IL-4 and -6 mRNA transcriptions. Importantly, the hypomethylation of the CpG islands in the IL-4 and -6 promoters displayed in SLE patients was similar to that of healthy T cells treated with 5-azaC. Finally, the hypomethylation levels of the CpG islands in the IL-4 and -6 promoters in lupus patients were significantly correlated to the IL-4 and -6 expressions.
The hypomethylation of the CpG islands of the IL-4 and -6 promoters accrued in T cells from SLE patients and was associated with the severity of SLE at the clinic.
DNA甲基化调节基因表达，且低甲基化与系统性红斑狼疮（SLE）中T细胞功能异常相关。然而，关于SLE患者白细胞介素（IL）-4和-6启动子的甲基化水平知之甚少。
从20例SLE患者和10例健康对照中分离T细胞，在有或无5-氮杂胞苷（5-azaC）存在的情况下进行体外激活，并用半定量逆转录聚合酶链反应（RT-PCR）对其IL-4和-6转录本进行鉴定。对其基因组DNA进行亚硫酸氢盐修饰后，通过巢式PCR和直接测序确定IL-4或-6启动子中的DNA甲基化水平。
与对照组相比，SLE患者T细胞中IL-4和-6 mRNA转录本水平显著更高。此外，用5-azaC处理健康T细胞可使IL-4或-6启动子中的CpG岛去甲基化，并增加IL-4和-6 mRNA转录。重要的是，SLE患者中IL-4和-6启动子中CpG岛的低甲基化与用5-azaC处理的健康T细胞相似。最后，狼疮患者中IL-4和-6启动子中CpG岛的低甲基化水平与IL-4和-6表达显著相关。
SLE患者T细胞中IL-4和-6启动子的CpG岛发生低甲基化，且与临床SLE的严重程度相关。
