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Background: Allergic diseases are more common in Finland than in Estonia, which—according to the biodiversity hypothesis—could relate to differences in early microbial exposures. Methods: We aimed at defining possible microbial perturbations preceding early atopic sensitization. Stool, nasal and skin samples of 6‐month‐old DIABIMMUNE study participants with HLA susceptibility to type 1 diabetes were collected. We compared microbiotas of sensitized (determined by specific IgE results at 18 months of age) and unsensitized Estonian and Finnish children. Results: Sensitization was differentially targeted between populations, as egg‐specific and birch pollen‐specific IgE was more common in Finland. Microbial diversity and community composition also differed; the genus Acinetobacter was more abundant in Estonian skin and nasal samples. Particularly, the strain‐level profile of Acinetobacter lwoffii was more diverse in Estonian samples. Early microbiota was not generally associated with later sensitization. Microbial composition tended to differ between children with or without IgE‐related sensitization, but only in Finland. While land‐use pattern (ie green areas vs. urban landscapes around the children's homes) was not associated with microbiota as a whole, it associated with the composition of the genus Acinetobacter. Breastfeeding affected gut microbial composition and seemed to protect from sensitization. Conclusions: In accordance with the biodiversity hypothesis, our results support disparate early exposure to environmental microbes between Finnish and Estonian children and suggest a significant role of the genus Acinetobacter in the allergy gap between the two populations. The significance of the observed differences for later allergic sensitization remains open. [ABSTRACT FROM AUTHOR]

Background: Atopic allergy is much more common in Finnish compared with Russian Karelia, although these areas are geographically and genetically close. To explore the role of environmental chemicals on the atopy difference a random sample of 200 individuals, 25 atopic and 25 non-atopic school-aged children and their mothers, were studied. Atopy was defined as having at least one positive skin prick test response to 14 common inhalant and food allergens tested. Concentrations of 11 common environmental pollutants were measured in blood samples. Results: Overall, the chemical levels were much higher in Russia than in Finland, except for 2,2',4,4'-tetra-bromodiphenyl ether (BDE47). In Finland but not in Russia, the atopic children had higher concentrations of polychlorinated biphenyls and 1,1-Dichloro-2,2-bis-(p-chlorophenyl)-ethylene (DDE) than the non-atopic children. In Russia but not in Finland, the atopic mothers had higher DDE concentrations than the non-atopic mothers. Conclusions: Higher concentrations of common environmental chemicals were measured in Russian compared with Finnish Karelian children and mothers. The chemicals did not explain the higher prevalence of atopy on the Finnish side. [ABSTRACT FROM AUTHOR]

Background: Modern lifestyle and urbanization have been associated with a raised risk for atopic diseases whereas early and long-term exposure to a farm environment confers protection against atopic sensitization. Immunomodulatory potential and microbiological characteristics of settled airborne dust from an urban house and a barn were examined. Methods: Pulmonary inflammation was induced in mice by repeated intranasal administration of dusts. Monocyte-derived human dendritic cells (moDCs) were exposed to dusts followed by coculture with purified naïve T cells. Cytokine/chemokine mRNA and protein levels were analyzed by real-time polymerase chain reaction, enzyme-linked immunosorbent assay and flow cytometry. The dusts were analyzed by cloning and sequencing of 16S rRNA genes (290 sequences) for DNA, lipids, endotoxin and β-glucan, by live-dead staining, viable counting, isolation and identification of pure cultures (n = 76). Results: Repeated exposure to house dust elicited pulmonary eosinophilia in mice whereas exposure to barn dust elicited neutrophilic and lymphocytic airway inflammation. Stimulation of moDCs with urban house dust elicited expression of Th2-promoting OX40L and Jagged-1 costimulatory molecules. Dendritic cells (DCs) exposed to house dust directed naïve T cells towards Th2 responses. Exposure of DCs to barn dust elicited the development of Th1-dominated immune responses. Urban house dust contained bacterial debris almost exclusively of human commensal species (corynebacteria, streptococci) whereas barn dust comprised mainly intact, viable bacteria of high diversity and no commensal species. Conclusion: Contact to debris originating from human commensal bacteria in urban house dust elicited a Th2-type response whereas barn dust with high bacterial diversity directed the cells towards a Th1 response. Copyright © 2008 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background: Evidence of the influence of pathogen exposure on the development of atopy and atopic disease is not unequivocal. We investigated the association between markers of infections and occurrence of atopy among adults in eastern Finland and western Russia, two adjacent areas with profound differences in living conditions and lifestyles. Methods: Randomly selected adults aged 25–54 years from Finland (n = 790) and from Russia (n = 387) participated in the study. Skin prick tests were performed to 11 common airborne allergens, and at least one positive prick reaction was considered to indicate atopy. Antibodies to different pathogens including hepatitis A virus (HAV), Helicobacter pylori, Toxoplasma gondii, herpes simplex virus (HSV), Chlamydia pneumoniae and the periodontal pathogens Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans were measured. Results: In Finland 34.3% and in Russia 23.3% of the study population was atopic (p < 0.001). Seroprevalences to all these pathogens were significantly higher among the Russians. In multivariate logistic regression analysis, only H. pylori was inversely associated with atopy in Russia. A further stepwise analysis revealed that H. pylori alone can explain 32% of the difference in atopy between the countries, and T. gondii, A. actinomycetemcomitans, HSV and C. pneumoniae had a slightly additive effect, whereas, unexpectedly, seropositivity to HAV and, to a lesser extent, P. gingivalis had an opposite effect. The net result of the stepwise analysis showed that 44% of the difference in atopy between the countries could be explained by seropositivity to these seven pathogens. Conclusions: Seropositivity to select pathogens, particularly to H. pylori, could explain a substantial part of the difference in atopy prevalence between Finland and Russia. Exposure to HAV was not associated with protection against atopy in this adult population. Copyright © 2006 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Intense search has been going on to find factors responsible for the asthma and atopy epidemic in Western societies. Attention has increasingly been devoted to environmental saprophytes, which, in addition to gut commensals, might be the major players in the development and fine tuning of immunologic homeostasis. This review outlines current evidence for the role of environmental saprophytes in the development of atopic disease and considers the consequences of urbanization in reducing contacts with soil microorganisms. The major microbial components that have been shown to possess immunomodulatory capacity and their respective Toll-like receptors are also discussed, as are the possible mechanisms underlying the ability of saprophytes to confer protection against atopic disease. [Copyright &y& Elsevier]

Background and objective: Western lifestyle has consistently been associated with the current asthma and atopy epidemics. We examined the occurrence and risk factors of atopy among schoolchildren and their mothers in 2 geographically adjacent areas with fundamental differences in living conditions and lifestyles. Methods: A population-based study of 2 generations was carried out in eastern Finland and in western Russia. Randomly selected schoolchildren aged 7 to 16 years (367 in Finland and 446 in Russia) and their mothers (365 and 437, respectively) were enrolled. Data were obtained by using a modified International Study of Asthma and Allergies in Childhood questionnaire and by performing skin prick tests against 14 common airborne and food allergens. Results: In children a 4-fold higher risk for atopy (≥1 positive prick test result) was found in Finland compared with Russia. Sensitization rates in Finland were generally higher among children compared with those of their mothers, whereas in Russia the opposite trends emerged. Parental farming in early life (<1 year) in Finland (odds ratio [OR], 0.53; 95% CI, 0.28-0.99) and in Russia (OR, 0.47; 95% CI, 0.22-1.03) and currently in Finland (OR, 0.45; 95% CI, 0.22-0.91) conferred protection against atopy. Having pets, dogs in Finland (OR, 0.57; 95% CI, 0.35-0.95) and cats in Russia (OR, 0.43; 95% CI, 0.24-0.80), in early life was also inversely associated with atopy. Conclusion: Atopy was several-fold more common in Finland compared with in Russia, and disparities in sensitization rates between the countries have further increased during these generations. The similarity of explanatory variables of atopy in both countries suggests that determinants of atopy are shared, at least in similar geoclimatic conditions. [Copyright &y& Elsevier]

Background The human commensal microbiota interacts in a complex manner with the immune system, and the outcome of these interactions might depend on the immune status of the subject. Objective Previous studies have suggested a strong allergy-protective effect for Gammaproteobacteria. Here we analyze the skin microbiota, allergic sensitization (atopy), and immune function in a cohort of adolescents, as well as the influence of Acinetobacter species on immune responses in vitro and in vivo . Methods The skin microbiota of the study subjects was identified by using 16S rRNA sequencing. PBMCs were analyzed for baseline and allergen-stimulated mRNA expression. In in vitro assays human monocyte-derived dendritic cells and primary keratinocytes were incubated with Acinetobacter lwoffii . Finally, in in vivo experiments mice were injected intradermally with A lwoffii during the sensitization phase of the asthma protocol, followed by readout of inflammatory parameters. Results In healthy subjects, but not in atopic ones, the relative abundance of Acinetobacter species was associated with the expression of anti-inflammatory molecules by PBMCs. Moreover, healthy subjects exhibited a robust balance between anti-inflammatory and T H 1/T H 2 gene expression, which was related to the composition of the skin microbiota. In cell assays and in a mouse model, Acinetobacter species induced strong T H 1 and anti-inflammatory responses by immune cells and skin cells and protected against allergic sensitization and lung inflammation through the skin. Conclusion These results support the hypothesis that skin commensals play an important role in tuning the balance of T H 1, T H 2, and anti-inflammatory responses to environmental allergens. [ABSTRACT FROM AUTHOR]