Contrasting microbiotas between Finnish and Estonian infants: Exposure to Acinetobacter may contribute to the allergy gap

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 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.

Biodiversity for resilience—What is needed for allergic children

“…Bacteria characterize best the differences in microbial communities and are not equal in their immunomodulating potential. For example, Acinetobacter species, both on human skin and on mice, are effective immunoregulators and associated with allergy and asthma risk 10‐12 . Maternal carriage of Prevotella copri during pregnancy decreases the offspring's risk of allergic disease and asthma 13 .…”

“…For example, Acinetobacter species, both on human skin and on mice, are effective immunoregulators and associated with allergy and asthma risk. [10][11][12] Maternal carriage of Prevotella copri during pregnancy decreases the offspring's risk of allergic disease and asthma. 13 In the gut, Morganella species has a potential causal effect on major depressive disorder.…”

Public Health struggles to square hygiene with diversity

“…Similar findings have come from Finland, which has become a hot bed of comparative studies between sub-populations in close proximity with contrasting microbial exposures. A recent study provided evidence that relative exposures to one particular bacterium common in the rural environment, Acinetobacter, correlates with a striking difference in allergy risk between infants in Finland and nearby Estonia (Ruokolainen et al, 2020). This study reported significant differences in microbial diversity and community composition with the genus Acinetobacter more abundant among Estonians whose children have a lower risk of allergy than Finnish children.…”

“…Similar findings have come from Finland, which has become a hot bed of comparative studies between sub‐populations in close proximity with contrasting microbial exposures. A recent study provided evidence that relative exposures to one particular bacterium common in the rural environment, Acinetobacter , correlates with a striking difference in allergy risk between infants in Finland and nearby Estonia (Ruokolainen et al , ).…”

The Earth-Connected Human Superorganism Vs. The Machine

“…(Table 1) [28][29][30][31][32][33][34][35][36][37][38][39] Illustrates examples of key microbes in different body location that carry out significant function for the whole human.…”