The transcription factor interferon regulatory factor 5 (IRF5), in the type I interferon pathway is involved in the genetic susceptibility to various autoimmune diseases. A 5-bp insertion/deletion (CGGGG indel) polymorphism in the promoter region of IRF5 associated with primary Sjögren's syndrome (pSS) could be epigenetically deregulated in this condition. Therefore, we investigated DNA methylation patterns of the promoter region of IRF5 to determine whether its epigenetic deregulation could explain the increased expression of IRF5 mRNA in pSS patients, along with the risk of pSS induced by the genetic polymorphism. DNA extracted from total peripheral blood mononuclear cells, isolated CD4(+) T cells, B lymphocytes and monocytes from 19 pSS patients and 24 healthy controls underwent methylation analysis by pyrosequencing. Salivary gland epithelial cells (SGECs) were cultured from minor salivary glands. Regions of interest in the CGGGG repeat and ATG initiation codon region were amplified by PCR and analysed by pyrosequencing. The effect of the demethylating agent 5-AzaC on IRF5 mRNA expression in controls was quantified by RT-PCR. Among the healthy controls, the mean methylation of the nine CpG pairs of the CGGGG repeat region and the 18 CpG pairs of the ATG region was < 15% in CD4(+) T cells, B lymphocytes, monocytes and SGECs. Patients and controls did not differ in methylation profiles as regards CD4(+) T cells and B lymphocytes. IRF5 mRNA expression did not differ with or without 5-AzaC in controls. The absence of aberrant DNA methylation profiles for the putative regulatory regions of IRF5 in CD4(+) T cells, B lymphocytes, and monocytes from patients with pSS, does not support the hypothesis that epigenetic deregulation in combination with the genetic polymorphism explains the increase in IRF5 mRNA levels in pSS patients.

中文翻译：

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IRF5启动子区域在原发性干燥综合征中的甲基化分布。

I型干扰素途径中的转录因子干扰素调节因子5（IRF5）与多种自身免疫性疾病的遗传易感性有关。与原发性干燥综合征（pSS）相关的IRF5启动子区域的5 bp插入/删除（CGGGG indel）多态性在这种情况下可以表观遗传失调。因此，我们调查了IRF5启动子区域的DNA甲基化模式，以确定其表观遗传失调是否可以解释pSS患者中IRF5 mRNA表达的增加，以及由遗传多态性引起的pSS风险。从全部19名pSS患者和24名健康对照的外周血单核细胞，分离的CD4（+）T细胞，B淋巴细胞和单核细胞中提取的DNA通过焦磷酸测序进行甲基化分析。唾液腺上皮细胞（SGEC）从次要的唾液腺培养。通过PCR扩增CGGGG重复序列和ATG起始密码子区域中的感兴趣区域，并通过焦磷酸测序进行分析。通过RT-PCR量化去甲基化剂5-AzaC对对照中IRF5mRNA表达的影响。在健康对照中，在CD4（+）T细胞，B淋巴细胞，单核细胞和SGEC中，CGGGG重复区域的9个CpG对和ATG区的18个CpG对的平均甲基化<15％。患者和对照组在CD4（+）T细胞和B淋巴细胞的甲基化方面没有差异。有或没有5-AzaC的对照组中，IRF5 mRNA表达没有差异。在CD4（+）T细胞，B淋巴细胞，IRF5的假定调控区域中，没有异常的DNA甲基化谱，