title: Patterns in the skin microbiota differ in children and teenagers between rural and urban environments.
abstract: The composition of human microbiota is affected by a multitude of factors. Understanding the dynamics of our microbial communities is important for promoting human health because microbiota has a crucial role in the development of inflammatory diseases, such as allergies. We have studied the skin microbiota of both arms in 275 Finnish children of few months old to teenagers living in contrasting environments. We show that while age is a major factor affecting skin microbial composition, the living environment also discriminates the skin microbiota of rural and urban children. The effect of environment is age-specific; it is most prominent in toddlers but weaker for newborns and non-existent for teenagers. Within-individual variation is also related to age and environment. Surprisingly, variation between arms is smaller in rural subjects in all age groups, except in teenagers. We also collected serum samples from children for characterization of allergic sensitization and found a weak, but significant association between allergic sensitization and microbial composition. We suggest that physiological and behavioral changes, related to age and the amount of contact with environmental microbiota, jointly influence the dynamics of the skin microbiota, and explain why the association between the living environment skin microbiota is lost in teenager.
authors.affiliation: Department of Biosciences, University of Helsinki, FI-00014 Helsinki, Finland.
authors.forename: Jenni
authors.initials: J
authors.lastname: Lehtimäki
authors.affiliation: Department of Biosciences, University of Helsinki, FI-00014 Helsinki, Finland.
authors.forename: Antti
authors.initials: A
authors.lastname: Karkman
authors.affiliation: National Institute for Health and Welfare, FI-00271 Helsinki, Finland.
authors.forename: Tiina
authors.initials: T
authors.lastname: Laatikainen
authors.affiliation: National Institute for Health and Welfare, FI-00271 Helsinki, Finland.
authors.forename: Laura
authors.initials: L
authors.lastname: Paalanen
authors.affiliation: Skin and Allergy Hospital, Helsinki University Central Hospital, FI-00029 Helsinki, Finland.
authors.forename: Leena
authors.initials: L
authors.lastname: von Hertzen
authors.affiliation: Skin and Allergy Hospital, Helsinki University Central Hospital, FI-00029 Helsinki, Finland.
authors.forename: Tari
authors.initials: T
authors.lastname: Haahtela
authors.affiliation: Department of Biosciences, University of Helsinki, FI-00014 Helsinki, Finland.
authors.forename: Ilkka
authors.initials: I
authors.lastname: Hanski
authors.affiliation: Department of Biosciences, University of Helsinki, FI-00014 Helsinki, Finland.
authors.forename: Lasse
authors.initials: L
authors.lastname: Ruokolainen
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004783:Environmental Microbiology; D005260:Female; D005387:Finland; D006801:Humans; D007223:Infant; D008297:Male; D064307:Microbiota; D012424:Rural Population; D012867:Skin / Q000382:microbiology*; D014505:Urban Population