title: DNA methylation profiles of airway epithelial cells and PBMCs from healthy, atopic and asthmatic children.
abstract: BACKGROUND
  Allergic inflammation is commonly observed in a number of conditions that are associated with atopy including asthma, eczema and rhinitis. However, the genetic, environmental or epigenetic factors involved in these conditions are likely to be different. Epigenetic modifications, such as DNA methylation, can be influenced by the environment and result in changes to gene expression.
  
  
  OBJECTIVE
  To characterize the DNA methylation pattern of airway epithelial cells (AECs) compared to peripheral blood mononuclear cells (PBMCs) and to discern differences in methylation within each cell type amongst healthy, atopic and asthmatic subjects.
  
  
  METHODS
  PBMCs and AECs from bronchial brushings were obtained from children undergoing elective surgery for non-respiratory conditions. The children were categorized as atopic, atopic asthmatic, non-atopic asthmatic or healthy controls. Extracted DNA was bisulfite treated and 1505 CpG loci across 807 genes were analyzed using the Illumina GoldenGate Methylation Cancer Panel I. Gene expression for a subset of genes was performed using RT-PCR.
  
  
  RESULTS
  We demonstrate a signature set of CpG sites that are differentially methylated in AECs as compared to PBMCs regardless of disease phenotype. Of these, 13 CpG sites were specific to healthy controls, 8 sites were only found in atopics, and 6 CpGs were unique to asthmatics. We found no differences in the methylation status of PBMCs between disease phenotypes. In AECs derived from asthmatics compared to atopics, 8 differentially methylated sites were identified including CpGs in STAT5A and CRIP1. We demonstrate STAT5A gene expression is decreased whereas CRIP1 gene expression is elevated in the AECs from asthmatic compared to both healthy and atopic subjects.
  
  
  CONCLUSIONS
  We characterized a cell specific DNA methylation signature for AECs compared to PBMCs regardless of asthmatic or atopic status. Our data highlight the importance of understanding DNA methylation in the epithelium when studying the epithelial contribution to asthma.
authors.affiliation: Department of Medicine, James Hogg Research Centre at the Heart and Lung Institute, University of British Columbia and St Paul's Hospital, Vancouver, British Columbia, Canada.
authors.forename: Dorota
authors.initials: D
authors.lastname: Stefanowicz
authors.forename: Tillie-Louise
authors.initials: TL
authors.lastname: Hackett
authors.forename: Farshid S
authors.initials: FS
authors.lastname: Garmaroudi
authors.forename: Oliver P
authors.initials: OP
authors.lastname: Günther
authors.forename: Sarah
authors.initials: S
authors.lastname: Neumann
authors.forename: Erika N
authors.initials: EN
authors.lastname: Sutanto
authors.forename: Kak-Ming
authors.initials: KM
authors.lastname: Ling
authors.forename: Michael S
authors.initials: MS
authors.lastname: Kobor
authors.forename: Anthony
authors.initials: A
authors.lastname: Kicic
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Stick
authors.forename: Peter D
authors.initials: PD
authors.lastname: Paré
authors.forename: Darryl A
authors.initials: DA
authors.lastname: Knight
mesh_terms: D000293:Adolescent; D001249:Asthma / Q000235:genetics* / Q000473:pathology; D001980:Bronchi / Q000473:pathology*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D018899:CpG Islands / Q000235:genetics; D019175:DNA Methylation / Q000235:genetics*; D003710:Demography; D004847:Epithelial Cells / Q000378:metabolism* / Q000473:pathology; D005260:Female; D005786:Gene Expression Regulation; D006262:Health; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000235:genetics* / Q000473:pathology; D060588:LIM Domain Proteins / Q000235:genetics / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000378:metabolism*; D008297:Male; D010641:Phenotype; D050799:STAT5 Transcription Factor / Q000235:genetics / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: C486181:CRIP1 protein, human; D002352:Carrier Proteins; D060588:LIM Domain Proteins; D050799:STAT5 Transcription Factor; C494092:STAT5A protein, human; D025521:Tumor Suppressor Proteins