Sánchez Elena, Palomino-Morales Rogelio J, Ortego-Centeno Norberto, Jiménez-Alonso Juan, González-Gay Miguel A, López-Nevot Miguel A, Sánchez-Román Julio, de Ramón Enrique, González-Escribano M Francisca, Pons-Estel Bernardo A, D'Alfonso Sandra, Sebastiani Gian Domenico, Alarcón-Riquelme Marta E, Martín Javier
Instituto de Parasitología y Biomedicina López-Neyra, CSIC, Granada 18100, Spain.
Hum Mol Genet. 2009 Oct 1;18(19):3739-48. doi: 10.1093/hmg/ddp301. Epub 2009 Jul 7.
Interleukin-18 (IL-18) is a proinflammatory cytokine that plays an important role in chronic inflammation and autoimmune disorders. In this study, we aimed to determine the potential role of the IL18 gene in SLE. To define the genetic association of the IL18 and SLE, we have genotyped nine SNPs in an independent set of Spanish cases and controls. The IL18 polymorphisms were genotyped by PCR, using a predeveloped TaqMan allele discrimination assay. Two SNPs were still significant after fine mapping of the IL18 gene. The SNP (rs360719) surviving correction for multiple tests was genotyped in two replication cohorts from Italy and Argentina. After the analysis, a significance with rs360719 C-allele remained across the sets and after the meta-analysis (Pooled OR = 1.37, 95% CI 1.21-1.54, combined P = 3.8E-07, Pc = 1.16E-06). Quantitative real-time PCR was performed to assess IL18 mRNA expression in PBMC from subjects with different IL18 rs360719 genotypes. We tested the effect of the IL18 rs360719 polymorphism on the transcription of IL18 by electrophoretic mobility shift assay and western blot. We found a significant increase in the relative expression of IL18 mRNA in individuals carrying the rs360719 C-risk allele; in addition we show that the polymorphism creates a binding site for the transcriptional factor OCT-1. These findings suggest that the novel IL18 rs360719 variant may play an important role in determining the susceptibility to SLE and it could be a key factor in the expression of the IL18 gene.
白细胞介素-18（IL-18）是一种促炎细胞因子，在慢性炎症和自身免疫性疾病中起重要作用。在本研究中，我们旨在确定IL18基因在系统性红斑狼疮（SLE）中的潜在作用。为了明确IL18与SLE的遗传关联，我们在一组独立的西班牙病例和对照中对9个单核苷酸多态性（SNP）进行了基因分型。使用预先开发的TaqMan等位基因鉴别分析通过聚合酶链反应（PCR）对IL18多态性进行基因分型。在对IL18基因进行精细定位后，有两个SNP仍然具有显著性。在来自意大利和阿根廷的两个重复队列中对经过多重检验校正后仍存活的SNP（rs360719）进行了基因分型。分析后，rs360719 C等位基因在各数据集以及荟萃分析后仍具有显著性（合并比值比=1.37，95%置信区间1.21-1.54，合并P=3.8×10⁻⁷，校正后P=1.16×10⁻⁶）。进行定量实时聚合酶链反应以评估来自具有不同IL18 rs360719基因型受试者的外周血单个核细胞（PBMC）中IL18信使核糖核酸（mRNA）的表达。我们通过电泳迁移率变动分析和蛋白质免疫印迹法检测了IL18 rs360719多态性对IL18转录的影响。我们发现携带rs360719 C风险等位基因的个体中IL18 mRNA的相对表达显著增加；此外，我们表明该多态性为转录因子OCT-1创造了一个结合位点。这些发现表明，新的IL18 rs360719变异体可能在决定SLE易感性方面起重要作用，并且它可能是IL18基因表达的关键因素。
