title: Prenatal farm exposure is related to the expression of receptors of the innate immunity and to atopic sensitization in school-age children.
abstract: BACKGROUND
  There is increasing evidence that environmental exposures determining childhood illnesses operate early in life. Prenatal exposure to a farming environment through the mother might also play an important role.
  
  
  OBJECTIVE
  We sought to investigate the role of maternal exposures to environments rich in microbial compounds for the development of atopic sensitization, asthma, and corresponding alterations in the innate immune system in offspring.
  
  
  METHODS
  In the children of the cross-sectional Prevention of Allergy Risk Factors for Sensitization in Children Related to Farming and Anthroposophic Life Style study, asthma and atopy were assessed by means of standardized questionnaires (n = 8263) and serum IgE measurements (n = 2086). In a subsample (n = 322) gene expression of Toll-like receptors (TLR2 and TLR4) and CD14 was assessed. Maternal exposures were defined through questionnaire information.
  
  
  RESULTS
  Both atopic sensitization (adjusted odds ratio, 0.58; 95% CI, 0.39-0.86) and the gene expression of receptors of innate immunity were strongly determined by maternal exposure to stables during pregnancy, whereas current exposures had much weaker or no effects. A dose-response relation was found between the extent of upregulation of these genes and the number of different farm animal species the mother had encountered in her pregnancy. Each additional farm animal species increased the expression of TLR2, TLR4, and CD14 by a factor of 1.16 (95% CI, 1.07-1.26), 1.12 (95% CI, 1.04-1.2), and 1.10 (95% CI, 1.03-1.23), respectively.
  
  
  CONCLUSIONS
  Maternal exposure to an environment rich in microbial compounds might protect against the development of atopic sensitization and lead to upregulation of receptors of the innate immune system. The underlying mechanisms potentially operating through the intrauterine milieu or epigenetic inheritance await further elucidation.
  
  
  CONCLUSIONS
  When assessing risk factors of allergies in an infant's medical history, attention must also be paid to environmental exposures affecting the mother.
authors.affiliation: University Children's Hospital Munich, Germany. markus.ege@med.uni-muenchen.de
authors.forename: Markus Johannes
authors.initials: MJ
authors.lastname: Ege
authors.forename: Christian
authors.initials: C
authors.lastname: Bieli
authors.forename: Remo
authors.initials: R
authors.lastname: Frei
authors.forename: Robert Theodoor
authors.initials: RT
authors.lastname: van Strien
authors.forename: Josef
authors.initials: J
authors.lastname: Riedler
authors.forename: Ellen
authors.initials: E
authors.lastname: Ublagger
authors.forename: Dieneke
authors.initials: D
authors.lastname: Schram-Bijkerk
authors.forename: Bert
authors.initials: B
authors.lastname: Brunekreef
authors.forename: Marianne
authors.initials: M
authors.lastname: van Hage
authors.forename: Annika
authors.initials: A
authors.lastname: Scheynius
authors.forename: Göran
authors.initials: G
authors.lastname: Pershagen
authors.forename: Marcus R
authors.initials: MR
authors.lastname: Benz
authors.forename: Roger
authors.initials: R
authors.lastname: Lauener
authors.forename: Erika
authors.initials: E
authors.lastname: von Mutius
authors.forename: Charlotte
authors.initials: C
authors.lastname: Braun-Fahrländer
mesh_terms: D000293:Adolescent; D000822:Animal Husbandry; D000818:Animals; D000829:Animals, Domestic; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005060:Europe; D005260:Female; D015870:Gene Expression; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000209:etiology* / Q000276:immunology; D007113:Immunity, Innate; D007112:Immunity, Maternally-Acquired; D018950:Lipopolysaccharide Receptors / Q000235:genetics / Q000378:metabolism; D008297:Male; D016273:Occupational Exposure; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000276:immunology*; D012337:RNA, Ribosomal, 18S / Q000235:genetics / Q000378:metabolism; D011971:Receptors, Immunologic / Q000235:genetics / Q000378:metabolism*; D051195:Toll-Like Receptor 2 / Q000235:genetics / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000378:metabolism
chemical_list: D018950:Lipopolysaccharide Receptors; D012337:RNA, Ribosomal, 18S; D011971:Receptors, Immunologic; C495342:TLR2 protein, human; C495345:TLR4 protein, human; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4