Prenatal farm exposure is related to the expression of receptors of the innate immunity and to atopic sensitization in school-age children.
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.
Ege
Markus Johannes
MJ
University Children's Hospital Munich, Germany. markus.ege@med.uni-muenchen.de
Bieli
Christian
C
Frei
Remo
R
van Strien
Robert Theodoor
RT
Riedler
Josef
J
Ublagger
Ellen
E
Schram-Bijkerk
Dieneke
D
Brunekreef
Bert
B
van Hage
Marianne
M
Scheynius
Annika
A
Pershagen
Göran
G
Benz
Marcus R
MR
Lauener
Roger
R
von Mutius
Erika
E
Braun-Fahrländer
Charlotte
C
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
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