Prenatal farm exposure is related to the expression of receptors of the innate immunity and to atopic sensitization in school-age children

University Children's Hospital Munich, Germany.
Journal of Allergy and Clinical Immunology (Impact Factor: 11.25). 05/2006; 117(4):817-23. DOI: 10.1016/j.jaci.2005.12.1307
Source: PubMed

ABSTRACT 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.
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.
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.
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.
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.
When assessing risk factors of allergies in an infant's medical history, attention must also be paid to environmental exposures affecting the mother.

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Available from: Christian Bieli, Mar 18, 2015
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    • "September 2012 | Volume 3 | Article 171 | 1 Toh et al. Probiotic therapy for allergic disease or asthma (Riedler et al., 2001), while prenatal farm exposure modulates atopic sensitization later in life (Ege et al., 2006). The human intestinal microbiota represents the most significant microbial exposure for the developing infant. "
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    • "Robust epidemiological data linking early environmental exposures to the development of allergies have been obtained in studies of European children born to farming and non-farming families, which show that farmer's children develop less atopy or asthma (Braun-Fahrlander et al. 1999; Riedler et al. 2000; Von Ehrenstein et al. 2000). The maternal exposure to stables and farm animals during pregnancy , was strongly associated with up-regulation of innate immune receptors and lower degree of allergic sensitization in a child born to a farmer mother (Ege et al. 2006). In terms of cytokines, maternal exposure to microbial compounds and consumption of farm dairy products was associated with increased T helper 1 (Th1)-type (IFN-γ) and pro-inflammatory (TNF-α) cytokines in cord blood (Pfefferle et al. 2010). "
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