Background Traditional farming represents a unique model situation to investigate the relationship of early-life farm-related exposure and allergy protection. Objectives To investigate associations ...between maternal farm exposures and cytokine production in cord blood (CB) mononuclear cells in a prospective multinational birth cohort of 299 farm and 326 nonfarm children and their families. Methods Supernatants from phorbol 12-myristate 13-acetate/ionomycin–stimulated CB mononuclear cells were assessed for the production of IFN-γ, TNF-α, IL-5, IL-10, and IL-12. Results Significantly higher levels of IFN-γ and TNF-α in farm compared with nonfarm children were found, whereas IL-5, IL-10, and IL-12 levels did not differ between study groups. Maternal contact with different farm animal species and barns and consumption of farm-produced butter during pregnancy enhanced the production of proinflammatory CB cytokines, whereas maternal consumption of farm-produced yogurt resulted in significant lower levels of IFN-γ and TNF-α in umbilical blood. Conclusion Maternal exposure to farming activities and farm dairy products during pregnancy modulated cytokine production patterns of offspring at birth.
Background Children who grow up in a farming environment show lower levels of atopic sensitization, hay fever, and asthma than children of the same age not living in such an environment. A number of ...investigations provided good evidence that this is due to an early-life contact with cowsheds, farm animals, and/or consumption of products like raw milk. Also, it had been indicated that microorganisms might have an important effect on the development of allergies, and thus the question arose of which farm microbial organisms, their products, or both might induce or influence allergy-protective mechanisms. Objective We sought to gain further insight into the potential allergy-protective properties of microbes isolated from the farming environment. Methods Of a number of bacterial species identified in cowsheds of farms, 2 were selected, isolated, and characterized, namely Acinetobacter lwoffii F78 and Lactococcus lactis G121. The isolates were investigated with regard to their activation of pattern-recognition receptors, the maturation of human monocyte-derived dendritic cells, the upregulation of inflammatory cytokines, the TH 1-polarizing Notch ligand expression, and their influence on the allergic phenotype. Results It is shown that both bacterial isolates were able to reduce allergic reactions in mice, to activate mammalian cells in vitro , and to induce a TH 1-polarizing program in dendritic cells. Conclusion Our data strongly support the hygiene hypothesis, which states that an environment rich in microbiologic structures, such as a farming environment, might protect against the development of allergies. Clinical implications This work provides the first data on a potential application of cowshed bacteria in allergy protection.
Background Numerous epidemiologic studies have demonstrated an allergy-protective effect of farm life early in childhood. It has been hypothesized that environmental exposure to microbes may ...contribute to this effect. Because of their small size and thereby their potential for deposition in lower airways of small children, bacterial spores may be candidates for such allergy-protective effects. Objective To investigate immune responses elicited by exposure to Bacillus spores in experimental settings. Methods Animal shed and mattress dusts were analyzed for bacteria and fungi by aerobic and anaerobic growth. Bacillus licheniformis , the most prominent microorganism found in these samples, was investigated with respect to spore specific stimulation of pattern recognition receptors, monocyte-derived dendritic cells and TH -cell polarization in vitro as well as to the prevention of asthma development in a mouse model of allergic asthma. Results In vitro , B licheniformis spores activated a TH 1 cytokine expression profile. In vivo application of these spores resulted in less spore-specific but long-lasting immune activation preventing eosinophilia and goblet cell hyperplasia; however, they provoked an influx of neutrophils in lung tissue of asthmatic mice. Conclusion Bacterial spores may contribute to the allergy-protective properties of farming environments, but their persistence in the lung causes ongoing immune activation in mouse experiments.
Background It is currently discussed whether allergic sensitization may start in utero under the influence of the maternal immune system and environmental determinants. Objective To investigate the ...relationship between allergen-specific cord blood (CB) IgE levels, parental sensitization, CB cytokine production, and environmental influences. Methods As part of an ongoing multicenter birth cohort study, allergen-specific IgE antibodies against 20 common seasonal, perennial, and food allergens were measured in blood samples from 922 neonates, 922 mothers, and 835 fathers. Supernatants from stimulated CB cells were assessed for the production of IL-5, IFN-γ, IL-10, and TNF-α. Results Allergen-specific IgE antibodies were detectable in 23.9% of newborns. Contamination with maternal serum was excluded by several means of analyses, including the absence of IgA antibodies. Clear correlation between maternal and fetal IgE was found only for hen's egg, cow's milk, and soybean allergen. Fetal IgE correlated negatively with the level of IFN-γ production, but not with IL-5 and IL-10. Conclusion Allergen-specific IgE antibodies most probably of fetal origin are detectable in CB and correlate with a lowered CB IFN-γ production.
Background Phenotypes of childhood-onset asthma are characterized by distinct trajectories and functional features. For atopy, definition of phenotypes during childhood is less clear. Objective We ...sought to define phenotypes of atopic sensitization over the first 6 years of life using a latent class analysis (LCA) integrating 3 dimensions of atopy: allergen specificity, time course, and levels of specific IgE (sIgE). Methods Phenotypes were defined by means of LCA in 680 children of the Multizentrische Allergiestudie (MAS) and 766 children of the Protection against allergy: Study in Rural Environments (PASTURE) birth cohorts and compared with classical nondisjunctive definitions of seasonal, perennial, and food sensitization with respect to atopic diseases and lung function. Cytokine levels were measured in the PASTURE cohort. Results The LCA classified predominantly by type and multiplicity of sensitization (food vs inhalant), allergen combinations, and sIgE levels. Latent classes were related to atopic disease manifestations with higher sensitivity and specificity than the classical definitions. LCA detected consistently in both cohorts a distinct group of children with severe atopy characterized by high seasonal sIgE levels and a strong propensity for asthma; hay fever; eczema; and impaired lung function, also in children without an established asthma diagnosis. Severe atopy was associated with an increased IL-5/IFN-γ ratio. A path analysis among sensitized children revealed that among all features of severe atopy, only excessive sIgE production early in life affected asthma risk. Conclusions LCA revealed a set of benign, symptomatic, and severe atopy phenotypes. The severe phenotype emerged as a latent condition with signs of a dysbalanced immune response. It determined high asthma risk through excessive sIgE production and directly affected impaired lung function.
Background Cross-sectional studies have suggested that prenatal farm exposures might protect against allergic disease and increase the expression of receptors of the innate immune system. However, ...epidemiologic evidence supporting the association with atopic dermatitis remains inconsistent. Objective To study the association between prenatal farm-related exposures and atopic dermatitis in a prospective study. We further analyzed the association between the expression of innate immune genes at birth and atopic dermatitis. Methods A total of 1063 children who participated in a birth cohort study, Protection against Allergy-Study in Rural Environments, were included in this study. Doctor diagnosis of atopic dermatitis was reported by the parents from 1 to 2 years of age by questionnaire. Gene expression of Toll-like receptors (TLRs) and CD14 was assessed in cord blood leukocytes by quantitative PCR. Results Maternal contact with farm animals and cats during pregnancy had a significantly protective effect on atopic dermatitis in the first 2 years of life. The risk of atopic dermatitis was reduced by more than half among children with mothers having contact with 3 or more farm animal species during pregnancy compared with children with mothers without contact (adjusted odds ratio, 0.43; 95% CI, 0.19-0.97). Elevated expression of TLR5 and TLR9 in cord blood was associated with decreased doctor diagnosis of atopic dermatitis. A significant interaction between polymorphism in TLR2 and prenatal cat exposure was observed in atopic dermatitis. Conclusion Maternal contact with farm animals and cats during pregnancy has a protective effect on the development of atopic dermatitis in early life, which is associated with a lower expression of innate immune receptors at birth.
Background Previous cross-sectional surveys have suggested that maternal exposure to animal sheds during pregnancy exerted a protective effect on atopic sensitization in children lasting until school ...age. Objective We sought to evaluate the effects of maternal exposure to animal sheds and other farm-related exposures during pregnancy on cord blood IgE levels in a prospective birth cohort. Methods Pregnant women living in rural areas in Austria, Finland, France, Germany, and Switzerland were recruited in the third trimester of pregnancy. Information on maternal farm-related exposures, nutrition, and health during pregnancy was obtained by means of interviews. Specific IgE levels for food and common inhalant allergens were assessed in cord blood of 922 children and peripheral blood samples of their mothers. Results Different sensitization patterns in cord blood of farm and nonfarm children were observed. In multivariable analysis consumption of boiled, but not unboiled, farm milk during pregnancy was positively associated with specific IgE to cow's milk independently from maternal IgE. In contrast, there was an inverse relationship between maternal exposure to animal sheds and cord blood IgE levels against seasonal allergens (adjusted odds ratio, 0.38; 95% CI, 0.21-0.70). This association was not confounded by maternal IgE levels. Maternal contact with hay enhanced the protective effect of exposure to animal sheds on IgE levels to grass pollen in cord blood. Conclusions Maternal exposure during pregnancy influences atopic sensitization patterns in cord blood. The (microbial) context of allergen contact possibly modifies the risk of atopic sensitization.
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