Ethnic endotypes in pediatric atopic dermatitis depend on immunotype,
lipid composition, and microbiota of the skin
Abstract
Background: Atopic dermatitis (AD) endotypes differ with
ethnicity. We examined the skin microbiota, cytokine-, and
lipid-profiles in Greenlandic Inuit and Danish children with AD.
Methods: 25 Inuit children with AD and 25 Inuit control
children were clinically examined and compared to previously collected
data from 25 Danish children with AD. Skin tape strips and skin swabs
were collected from lesional and non-lesional skin. Levels of cutaneous
immune biomarkers, free sphingoid bases and their (glycosyl)ceramides
were analyzed. Skin swabs were analyzed with 16S rRNA and tuf
gene for characterization of bacterial species communities.
Results: Bacterial β-diversity was significantly different
between Inuit and Danish AD skin, in both lesional (p<0.001)
and non-lesional (p<0.001) AD skin, and there was a higher
relative abundance of Staphylococcus aureus in Danish compared to
Inuit lesional (53% vs. 8%, p<0.01) and non-lesional
skin (55% vs. 5%, p<0.001). Danish AD children had a
higher α-diversity than Inuit children in non-lesional (
p<0.05) but not in lesional skin. Significantly higher
levels of type 2 immunity cytokine interleukin (IL)-4 (p<0.05)
and IL-5 (p<0.01) were identified in Inuit compared to Danish
AD children. In contrast, IL-33 (p<0.01) was higher in Danish
lesional and non-lesional AD skin. Higher levels of long-chain
glucosylceramide (GlcCER)[S](d26:1) were found in lesional (
p<0.001) and non-lesional ( p<0.001)
Inuit skin compared with Danish AD skin. NMF levels were similar in
Inuit and Danish AD skin. Conclusion: Skin microbiota, cytokine
and lipid composition differed significantly between Inuit and Danish
children with AD and showed a stronger type 2 immune signature in Inuit
children.