Ethnic endotypes in paediatric atopic dermatitis depend on immunotype, lipid composition and microbiota of the skin

Abstract

BackgroundAtopic dermatitis (AD) endotypes differ with ethnicity. We examined the skin microbiota, cytokine‐, and lipid‐profiles in Greenlandic Inuit and Danish children with AD.Methods25 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.ResultsBacterial 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.ConclusionSkin 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.

Stratum Corneum Lipids in Non-Lesional Atopic and Healthy Skin following Moisturizer Application: A Randomized Clinical Experiment

“…The observed differences in SC lipid composition between the AD patients and the controls align with existing literature. Numerous studies have highlighted a reduction in ceramide chain length in AD patients [ 4 , 7 , 21 ], with a decrease in EO CERs and increase in C34 CERs, being more pronounced in lesional than non-lesional skin [ 7 , 22 ]. In our study, a non-significant elevation in the average ceramide chain length was noted in the control group compared with AD patients ( p = 0.056).…”

“…In previous SC studies, tape strips no. 3 or 4 have mostly been used for lipid measurements [ 22 , 29 , 30 ], which eases comparisons with our results, although others have been using several tapes pooled together [ 31 ]. Further, SC lipids and especially the CERs, which were the main interest of this study, have been shown to have a limited variability according to depth [ 16 ].…”