Celiac disease associated SNP rs17810546 is located in a gene silencing region
GENE
Authors: Zwiers, Antonie; van Wanrooij, Roy L. J.; Dieckman, Tessa; Nijeboer, Petula; Kraal, Georg; Bouma, Gerd
Abstract
GWAS studies have identified variant rs 17810546 in a non-coding region on chromosome 3 as a risk factor for several auto-immune diseases, including Celiac Disease. In silico analysis reveals that this variant is located in a transcription regulatory site. By means of reporter constructs we show that this region can override the expression rate of a gene as determined by its native promoter and that this modulation is influenced by the genetic composition of the haplotype which rs17810546 forms with a nearby other variant, rs761008. Secondly, we present data that this genetically imprinted modulation could be involved in Celiac Disease through the IL12A gene which is located 40 Kb downstream of this regulatory region. Based on our findings it is most likely that the IL12A gene does so as part of the cytokine IL-35.
Inorganic arsenic impairs differentiation and functions of human dendritic cells
TOXICOLOGY AND APPLIED PHARMACOLOGY
Authors: Macoch, Melinda; Morzadec, Claudie; Fardel, Olivier; Vernhet, Laurent
Abstract
Experimental studies have demonstrated that the antileukemic trivalent inorganic arsenic prevents the development of severe pro-inflammatory diseases mediated by excessive Th1 and Th17 cell responses. Differentiation of Th1 and Th17 subsets is mainly regulated by interleukins (ILs) secreted from dendritic cells (DCs) and the ability of inorganic arsenic to impair interferon-gamma and IL-17 secretion by interfering with the physiology of DCs is unknown. In the present study, we demonstrate that high concentrations of sodium arsenite (As(III), 1-2 mu M) clinically achievable in plasma of arsenic-treated patients, block differentiation of human peripheral blood monocytes into immature DCs (iDCs) by inducing their necrosis. Differentiation of monocytes in the presence of non-cytotoxic concentrations of As(III) (0.1 to 0.5 mu M) only slightly impacts endocytotic activity of iDCs or expression of co-stimulatory molecules in cells activated with lipopolysaccharide. However, this differentiation in the presence of As(III) strongly represses secretion of IL-12p70 and IL-23, two major regulators of Th1 and Th17 activities, from iDCs stimulated with different toll-like receptor (TLR) agonists in metalloid-free medium. Such As(III)-exposed DCs also exhibit reduced mRNA levels of IL12A and/or IL12B genes when activated with TLR agonists. Finally, differentiation of monocytes with non-cytotoxic concentrations of As(III) subsequently reduces the ability of activated DCs to stimulate the release of interferon-gamma and IL-17 from Th cells. In conclusion, our results demonstrate that clinically relevant concentrations of inorganic arsenic markedly impair in vitro differentiation and functions of DCs, which may contribute to the putative beneficial effects of the metalloid towards inflammatory autoimmune diseases. (C) 2012 Elsevier Inc. All rights reserved.