Background: DNA methylation profiles associated with childhood asthma might provide novel insights into disease pathogenesis. We did an epigenome-wide association study to assess methylation profiles associated with childhood asthma. Methods: We did a large-scale epigenome-wide association study (EWAS) within the Mechanisms of the Development of ALLergy (MeDALL) project. We examined epigenome-wide methylation using Illumina Infinium Human Methylation450 BeadChips (450K) in whole blood in 207 children with asthma and 610 controls at age 4-5 years, and 185 children with asthma and 546 controls at age 8 years using a cross-sectional case-control design. After identification of differentially methylated CpG sites in the discovery analysis, we did a validation study in children (4-16 years; 247 cases and 2949 controls) from six additional European cohorts and meta-analysed the results. We next investigated whether replicated CpG sites in cord blood predict later asthma in 1316 children. We subsequently investigated cell-type-specific methylation of the identified CpG sites in eosinophils and respiratory epithelial cells and their related gene-expression signatures. We studied cell-type specificity of the asthma association of the replicated CpG sites in 455 respiratory epithelial cell samples, collected by nasal brushing of 16-year-old children as well as in DNA isolated from blood eosinophils (16 with asthma, eight controls [age 2-56 years]) and compared this with whole-blood DNA samples of 74 individuals with asthma and 93 controls (age 1-79 years). Whole-blood transcriptional profiles associated with replicated CpG sites were annotated using RNA-seq data of subsets of peripheral blood mononuclear cells sorted by fluorescence-activated cell sorting. Findings: 27 methylated CpG sites were identified in the discovery analysis. 14 of these CpG sites were replicated and passed genome-wide significance (p<1·14 × 10-7) after meta-analysis. Consistently lower methylation levels were observed at all associated loci across childhood from age 4 to 16 years in participants with asthma, but not in cord blood at birth. All 14 CpG sites were significantly associated with asthma in the second replication study using whole-blood DNA, and were strongly associated with asthma in purified eosinophils. Whole-blood transcriptional signatures associated with these CpG sites indicated increased activation of eosinophils, effector and memory CD8 T cells and natural killer cells, and reduced number of naive T cells. Five of the 14 CpG sites were associated with asthma in respiratory epithelial cells, indicating cross-tissue epigenetic effects. Interpretation: Reduced whole-blood DNA methylation at 14 CpG sites acquired after birth was strongly associated with childhood asthma. These CpG sites and their associated transcriptional profiles indicate activation of eosinophils and cytotoxic T cells in childhood asthma. Our findings merit further investigations of the role of epigenetics in a clinical context. Funding: EU and the Seventh Framework Programme (the MeDALL project).

DNA methylation in childhood asthma: An epigenome-wide meta-analysis

Forastiere, Francesco;Fantini, Maria Pia;Gori, Davide;
2018

Abstract

Background: DNA methylation profiles associated with childhood asthma might provide novel insights into disease pathogenesis. We did an epigenome-wide association study to assess methylation profiles associated with childhood asthma. Methods: We did a large-scale epigenome-wide association study (EWAS) within the Mechanisms of the Development of ALLergy (MeDALL) project. We examined epigenome-wide methylation using Illumina Infinium Human Methylation450 BeadChips (450K) in whole blood in 207 children with asthma and 610 controls at age 4-5 years, and 185 children with asthma and 546 controls at age 8 years using a cross-sectional case-control design. After identification of differentially methylated CpG sites in the discovery analysis, we did a validation study in children (4-16 years; 247 cases and 2949 controls) from six additional European cohorts and meta-analysed the results. We next investigated whether replicated CpG sites in cord blood predict later asthma in 1316 children. We subsequently investigated cell-type-specific methylation of the identified CpG sites in eosinophils and respiratory epithelial cells and their related gene-expression signatures. We studied cell-type specificity of the asthma association of the replicated CpG sites in 455 respiratory epithelial cell samples, collected by nasal brushing of 16-year-old children as well as in DNA isolated from blood eosinophils (16 with asthma, eight controls [age 2-56 years]) and compared this with whole-blood DNA samples of 74 individuals with asthma and 93 controls (age 1-79 years). Whole-blood transcriptional profiles associated with replicated CpG sites were annotated using RNA-seq data of subsets of peripheral blood mononuclear cells sorted by fluorescence-activated cell sorting. Findings: 27 methylated CpG sites were identified in the discovery analysis. 14 of these CpG sites were replicated and passed genome-wide significance (p<1·14 × 10-7) after meta-analysis. Consistently lower methylation levels were observed at all associated loci across childhood from age 4 to 16 years in participants with asthma, but not in cord blood at birth. All 14 CpG sites were significantly associated with asthma in the second replication study using whole-blood DNA, and were strongly associated with asthma in purified eosinophils. Whole-blood transcriptional signatures associated with these CpG sites indicated increased activation of eosinophils, effector and memory CD8 T cells and natural killer cells, and reduced number of naive T cells. Five of the 14 CpG sites were associated with asthma in respiratory epithelial cells, indicating cross-tissue epigenetic effects. Interpretation: Reduced whole-blood DNA methylation at 14 CpG sites acquired after birth was strongly associated with childhood asthma. These CpG sites and their associated transcriptional profiles indicate activation of eosinophils and cytotoxic T cells in childhood asthma. Our findings merit further investigations of the role of epigenetics in a clinical context. Funding: EU and the Seventh Framework Programme (the MeDALL project).
2018
Xu, Cheng-Jian; Söderhäll, Cilla; Bustamante, Mariona; Baïz, Nour; Gruzieva, Olena; Gehring, Ulrike; Mason, Dan; Chatzi, Leda; Basterrechea, Mikel; Llop, Sabrina; Torrent, Maties; Forastiere, Francesco; Fantini, Maria Pia; Carlsen, Karin C Lødrup; Haahtela, Tari; Morin, Andréanne; Kerkhof, Marjan; Merid, Simon Kebede; van Rijkom, Bianca; Jankipersadsing, Soesma A.; Bonder, Marc Jan; Ballereau, Stephane; Vermeulen, Cornelis J.; Aguirre-Gamboa, Raul; de Jongste, Johan C.; Smit, Henriette A.; Kumar, Ashish; Pershagen, Göran; Guerra, Stefano; Garcia-Aymerich, Judith; Greco, Dario; Reinius, Lovisa; McEachan, Rosemary R.C.; Azad, Raf; Hovland, Vegard; Mowinckel, Petter; Alenius, Harri; Fyhrquist, Nanna; Lemonnier, Nathanaël; Pellet, Johann; Auffray, Charles; van der Vlies, Pieter; van Diemen, Cleo C.; Li, Yang; Wijmenga, Cisca; Netea, Mihai G.; Moffatt, Miriam F.; Cookson, William O.C.M.; Anto, Josep M.; Bousquet, Jean; Laatikainen, Tiina; Laprise, Catherine; Carlsen, Kai-Håkon; Gori, Davide; Porta, Daniela; Iñiguez, Carmen; Bilbao, Jose Ramon; Kogevinas, Manolis; Wright, John; Brunekreef, Bert; Kere, Juha; Nawijn, Martijn C.; Annesi-Maesano, Isabella; Sunyer, Jordi; Melén, Erik; Koppelman, Gerard H.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/632915
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