原標(biāo)題：兒童哮喘的DNA 甲基化：一個(gè)表觀基因組薈萃分析
　　與兒童哮喘有關(guān)的DNA甲基化特征可能為疾病發(fā)病機(jī)制提供新的見解。我們做了一個(gè)表觀遺傳關(guān)聯(lián)研究來(lái)評(píng)估甲基化與兒童哮喘的關(guān)系。
　　我們?cè)谶^(guò)敏發(fā)生機(jī)理研究(MeDALL)項(xiàng)目中進(jìn)行了一項(xiàng)大規(guī)模的表觀基因組關(guān)聯(lián)研究(EWAS)。
　　我們使用Illumina Infinium人類甲基化450 BeadChips (450K)在全血中檢測(cè)了207名哮喘患兒和610名4-5歲對(duì)照組，以及185名哮喘患兒和546名8歲對(duì)照組，采用橫斷面病例對(duì)照設(shè)計(jì)。在發(fā)現(xiàn)分析中鑒定出差異甲基化的CpG位點(diǎn)后，我們?cè)诹硗?個(gè)來(lái)自歐洲同期組群兒童(4-16歲; 247例病例和2949例對(duì)照)中進(jìn)行了驗(yàn)證，并對(duì)結(jié)果進(jìn)行meta分析。我們接著研究了在臍帶血中復(fù)制的CpG位點(diǎn)是否能預(yù)測(cè)1316名兒童日后的哮喘。隨后我們研究了嗜酸性粒細(xì)胞和呼吸道上皮細(xì)胞中CpG位點(diǎn)的細(xì)胞特異性甲基化及其相關(guān)基因表達(dá)特征。我們?cè)谕ㄟ^(guò)鼻腔灌洗收集的455例16歲兒童呼吸道上皮樣本和在從（16例哮喘，8例對(duì)照，年齡2-56歲）血液嗜酸性細(xì)胞分離的DNA中研究了被復(fù)制的CpG位點(diǎn)與哮喘相關(guān)的細(xì)胞型的特異性，并與74例哮喘個(gè)體和93例對(duì)照（1-79歲）的全血DNA樣本進(jìn)行比較。 與復(fù)制的CpG位點(diǎn)相關(guān)的全血轉(zhuǎn)錄情況用通過(guò)熒光激活細(xì)胞分選術(shù)分類的外周血單核細(xì)胞子集的RNA-seq數(shù)據(jù)進(jìn)行注釋。
　　在發(fā)現(xiàn)分析中鑒定了27個(gè)甲基化的CpG位點(diǎn)。其中的14個(gè)CpG位點(diǎn)被復(fù)制，經(jīng)meta-分選后通過(guò)全基因組意義(p < 1.14×10 - 7)。在4歲至16歲哮喘患兒中均觀察到一致性的低甲基化水平的所有相關(guān)位點(diǎn)，但在臍帶血中未觀察到，在第二次全血DNA復(fù)制研究中，發(fā)現(xiàn)所有14個(gè)CpG位點(diǎn)均與哮喘顯著相關(guān)。并且與純化的嗜酸性粒細(xì)胞密切相關(guān)。與這些CpG位點(diǎn)相關(guān)的全血轉(zhuǎn)錄特征提示嗜酸性粒細(xì)胞、效應(yīng)和記憶CD8 T細(xì)胞和自然殺傷細(xì)胞數(shù)量的增加和幼稚T細(xì)胞數(shù)量的下降。14個(gè)CpG位點(diǎn)中有5個(gè)在呼吸道上皮上與哮喘有關(guān)，提示跨組織表觀遺傳效應(yīng)。
　　出生后14個(gè)CpG位點(diǎn)的全血甲基化降低與兒童哮喘密切相關(guān)。這些CpG位點(diǎn)及其相關(guān)的轉(zhuǎn)錄譜顯示了嗜酸性粒細(xì)胞和細(xì)胞毒性T細(xì)胞在兒童哮喘中的激活。我們的發(fā)現(xiàn)值得進(jìn)一步研究表觀遺傳學(xué)在臨床環(huán)境中的作用
　　延伸閱讀


Respiratory
DNA methylation in childhood asthma: an epigenome-wide meta-analysis
DOI: 10.1016/52213-2600（18）30052-3
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 celltype-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 low methylation level were observed at all associated loci across childhood from age 4 to 16 years in participant with asthma ,but not in cord blood at birth , All14 CpG site were significantly associated with asthma in the second replication study using whole blood DNA. and were strongly associated with purified eosinophils. Whole- blood d transcriptional signatures associated with these CpG sites indicated increased eosinophils，effector and Memory CD8 T cells and natural killer cell ,and reduced  number of na?ve T cells. Five of the 14 CpG sites were associated with asthma in respiratory epithelials, indicating cross-tissue epigenetic effects.
Interpretation  
reduced whole-blood methylation at 14 CpG sites acquired after birth was strongly associated with childhood asthma . these CpG sites and their associated transcriptional profile indicated activation of eosinophils and cytotoxic Tcell in childhood asthma. our findings merit further investigations of the role of epigenetics in a clinic context.
First Author:
Correspondence:
All Authors:
Cheng-Jian Xu, Cilla S?derh?ll, Mariona Bustamante, Nour Ba?z, Olena Gruzieva, Ulrike Gehring, Dan Mason, Leda Chatzi, Mikel Basterrechea, Sabrina Llop, Maties Torrent, Francesco Forastiere, Maria Pia Fantini, Karin C L?drup Carlsen, Tari Haahtela, Andréanne Morin, Marjan Kerkhof, Simon Kebede Merid, Bianca van Rijkom, Soesma A Jankipersadsing, Marc Jan Bonder, Stephane Ballereau, Cornelis J Vermeulen, Raul Aguirre-Gamboa, Johan C de Jongste, Henriette A Smit, Ashish Kumar, G?ran Pershagen, Stefano Guerra, Judith Garcia-Aymerich, Dario Greco, Lovisa Reinius, Rosemary R C McEachan, Raf Azad, Vegard Hovland, Petter Mowinckel, Harri Alenius, Nanna Fyhrquist, Nathana?l Lemonnier, Johann Pellet, Charles Auffray, the BIOS Consortium, Pieter van der Vlies, Cleo C van Diemen, Yang Li, Cisca Wijmenga, Mihai G Netea, Miriam F Moffatt, William O C M Cookson, Josep M Anto, Jean Bousquet, Tiina Laatikainen, Catherine Laprise, Kai-H?kon Carlsen, Davide Gori, Daniela Porta, Carmen I?iguez, Jose Ramon Bilbao, Manolis Kogevinas, John Wright, Bert Brunekreef, Juha Kere, Martijn C Nawijn, Isabella Annesi-Maesano, Jordi Sunyer, Erik Melén*, Gerard H Koppelman*
　　創(chuàng)建過(guò)敏性疾病的科研、科普知識(shí)交流平臺(tái)，為過(guò)敏患者提供專業(yè)診斷、治療、預(yù)防的共享平臺(tái)。