Abstract：
We elucidated the effect of four known T1D-susceptibility associated single nucleotide polymorphism (SNP) markers in three genes (rs12722495 and rs2104286 in IL2RA, rs689 in INS and rs2476601 in PTPN22) on CpG site methylation of their proximal promoters in different lymphocyte subsets using pyrosequencing. The study cohort comprised 25 children with newly diagnosed T1D and 25 matched healthy controls. The rs689 SNP was associated with methylation at four CpG sites in INS promoter: -234, -206, -102 and -69. At all four CpG sites, the susceptibility genotype AA was associated with a higher methylation level compared to the other genotypes. We also found an association between rs12722495 and methylation at CpG sites -373 and -356 in IL2RA promoter in B cells, where the risk genotype AA was associated with lower methylation level compared to the AG genotype. The other SNPs analyzed did not demonstrate significant associations with CpG site methylation in the examined genes. Additionally, we compared the methylation between children with T1D and controls, and found statistically significant methylation differences at CpG -135 in INS in CD8+ T cells (p = 0.034), where T1D patients had a slightly higher methylation compared to controls (87.3 ± 7.2 vs. 78.8 ± 8.9). At the other CpG sites analyzed, the methylation was similar. Our results not only confirm the association between INS methylation and rs689 discovered in earlier studies but also report this association in sorted immune cells. We also report an association between rs12722495 and IL2RA promoter methylation in B cells. These results suggest that at least part of the genetic effect of rs689 and rs12722495 on T1D pathogenesis may be conveyed by DNA methylation.
摘要：
我们阐明了四个已知的T1D易感性相关单核苷酸多态性（SNP）标记在三个基因中的作用（IL2RA中的rs12722495和rs2104286，INS中的rs689和PTPN22中的rs2476601）使用焦磷酸测序对其在不同淋巴细胞亚群中近端启动子的CpG位点甲基化。该研究队列包括25名新诊断为T1D的儿童和25名匹配的健康对照。rs689SNP与INS启动子中四个CpG位点的甲基化相关:-234、-206、-102和-69。在所有四个CpG站点，与其他基因型相比,易感性基因型AA与较高的甲基化水平相关.我们还发现rs12722495与B细胞IL2RA启动子中CpG位点-373和-356的甲基化之间存在关联，与AG基因型相比，风险基因型AA与较低的甲基化水平相关。分析的其他SNP未显示与检查基因中CpG位点甲基化的显著关联。此外,我们比较了T1D患儿和对照组的甲基化，发现CD8+T细胞中INSCpG-135的甲基化差异有统计学意义（p=0.034），与对照组相比，T1D患者的甲基化略高（87.3±7.2vs.78.8±8.9)。在分析的其他CpG位点，甲基化相似。我们的结果不仅证实了早期研究中发现的INS甲基化与rs689之间的关联，而且还报道了分选免疫细胞中的这种关联。我们还报道了rs12722495与B细胞中IL2RA启动子甲基化之间的关联。这些结果表明，rs689和rs12722495对T1D发病机理的遗传效应的至少一部分可以通过DNA甲基化来传达。
