TY - JOUR T1 - An ankylosing spondylitis-associated genetic variant in the <em>IL23R-IL12RB2</em> intergenic region modulates enhancer activity and is associated with increased Th1-cell differentiation JF - Annals of the Rheumatic Diseases JO - Ann Rheum Dis SP - 2150 LP - 2156 DO - 10.1136/annrheumdis-2015-208640 VL - 75 IS - 12 AU - Amity R Roberts AU - Matteo Vecellio AU - Liye Chen AU - Anna Ridley AU - Adrian Cortes AU - Julian C Knight AU - Paul Bowness AU - Carla J Cohen AU - B Paul Wordsworth Y1 - 2016/12/01 UR - http://ard.bmj.com/content/75/12/2150.abstract N2 - Objectives To explore the functional basis for the association between ankylosing spondylitis (AS) and single-nucleotide polymorphisms (SNPs) in the IL23R-IL12RB2 intergenic region.Methods We performed conditional analysis on genetic association data and used epigenetic data on chromatin remodelling and transcription factor (TF) binding to identify the primary AS-associated IL23R-IL12RB2 intergenic SNP. Functional effects were tested in luciferase reporter assays in HEK293T cells and allele-specific TF binding was investigated by electrophoretic mobility gel shift assays. IL23R and IL12RB2 mRNA levels in CD4+ T cells were compared between cases homozygous for the AS-risk ‘A’ allele and the protective ‘G’ allele. The proportions of interleukin (IL)-17A+ and interferon (IFN)-γ+ CD4+ T-cells were measured by fluorescence-activated cell sorting and compared between these AS-risk and protective genotypes.Results Conditional analysis identified rs11209032 as the probable causal SNP within a 1.14 kb putative enhancer between IL23R and IL12RB2. Reduced luciferase activity was seen for the risk allele (p&lt;0.001) and reduced H3K4me1 methylation observed in CD4+ T-cells from ‘A/A’ homozygotes (p=0.02). The binding of nuclear extract to the risk allele was decreased ∼3.5-fold compared with the protective allele (p&lt;0.001). The proportion of IFN-γ+ CD4+ T-cells was increased in ‘A/A’ homozygotes (p=0.004), but neither IL23R nor IL12RB2 mRNA was affected.Conclusions The rs11209032 SNP downstream of IL23R forms part of an enhancer, allelic variation of which may influence Th1-cell numbers. Homozygosity for the risk ‘A’ allele is associated with more IFN-γ-secreting (Th1) cells. Further work is necessary to explain the mechanisms for these important observations. ER -