Abstract 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 sensitisation. 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 sensitised (determined by specific IgE-results at 18 months of age) and unsensitised Estonian and Finnish children. Results Sensitisation was differentially targeted between populations, as egg- 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 sensitisation. Microbial composition tended to differ between children with or without IgE-related sensitisation, but only in Finland. While land-use pattern (i.e. 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 sensitisation. 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 sensitisation remains open.
- atopic sensitisation
- 3111 Biomedicine