title: DNA methylation levels within the CD14 promoter region are lower in placentas of mothers living on a farm.
abstract: BACKGROUND
  Epigenetic regulation has been suggested to be a link between environmental intrauterine exposures and development of asthma and allergy. The placenta is an essential part of the intrauterine environment. We have previously found the innate immune receptor CD14 to be differentially expressed on the mRNA level in placentas in relation to lifestyle and parental allergen sensitization. We here hypothesized that the promoter region of CD14 may be subject to differential DNA methylation and therefore a link between intrauterine exposure and mRNA expression.
  
  
  METHODS
  Ninety-four placentas from the ALADDIN (Assessment of Lifestyle and Allergic Disease During Infancy) study were investigated. We used methylation-sensitive high-resolution melting (MS-HRM) analysis to semi-quantitatively analyze the DNA methylation of the promoter region of CD14 in 36 placentas known to have different CD14 mRNA expression. EpiTYPER was used to validate the MS-HRM data and to analyze an additional 58 placentas selected on mothers living on a farm or not.
  
  
  RESULTS
  MS-HRM analysis on 36 placenta samples revealed a relation between methylation of the CD14 promoter region with the level of CD14 mRNA expression. The MS-HRM and EpiTYPER data correlated highly significantly. EpiTYPER analysis of the additional 58 placentas demonstrated that DNA methylation in the CD14 promoter was significantly lower in placentas of mothers living on a farm compared with mothers not living on a farm.
  
  
  CONCLUSIONS
  Our data suggest that epigenetic regulation of CD14 in placenta might be involved in the protective effect of 'living on a farm', with regard to allergy development.
authors.affiliation: Department of Medicine Solna, Translational Immunology Unit, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Gisela G G
authors.initials: GG
authors.lastname: Slaats
authors.forename: Lovisa E
authors.initials: LE
authors.lastname: Reinius
authors.forename: Johan
authors.initials: J
authors.lastname: Alm
authors.forename: Juha
authors.initials: J
authors.lastname: Kere
authors.forename: Annika
authors.initials: A
authors.lastname: Scheynius
authors.forename: Maaike
authors.initials: M
authors.lastname: Joerink
mesh_terms: D000328:Adult; D001483:Base Sequence; D016000:Cluster Analysis; D019175:DNA Methylation; D004781:Environmental Exposure; D044127:Epigenesis, Genetic; D057890:Epigenomics; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D008019:Life Style; D018950:Lipopolysaccharide Receptors / Q000235:genetics*; D008969:Molecular Sequence Data; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D011401:Promoter Regions, Genetic; D015203:Reproducibility of Results; D055815:Young Adult
chemical_list: D018950:Lipopolysaccharide Receptors