Yuping Song

Eczema is a common inflammatory skin disorder during infancy. Evidence has shown that skin-microbiome fluctuations may precede eczema development, but their predictive value for eczema phenotypes remains unknown. We aimed to investigate the early-life evolution of the skin microbiome and its temporal associations with different pairs of eczema phenotypes (transient versus persistent, atopic versus non-atopic) in Chinese children. We followed 119 term Chinese infants from birth to 24 months old within a Hong Kong birth cohort. The skin microbes at the left antecubital fossa were serially sampled by flocked swabs at 1, 6, and 12 months for bacterial 16S rRNA gene sequencing. The atopic sensitization at 12 months was strongly associated with eczema persisting to 24 months (odds ratio 4.95, 95% confidence interval 1.29–19.01). Compared with those with non-atopic eczema, the children with atopic eczema had reduced alpha diversity at 12 months (p < 0.001) and transiently higher abundance of the genus Janibacter at 6 months (p < 0.001). Our findings suggest that atopic sensitization at 12 months may predict persistent eczema by 24 months, and atopic eczema at 12 months is associated with unique skin microbiome profiles at 6 and 12 months. Non-invasive skin-microbiome profiling may have predictive value for atopic eczema.

Background Eczema is a common skin inflammatory disease during infancy. Most paediatric patients develop eczema within 6 months of age, but the severity and persistence vary. While infantile eczema in most cases could improve or get resolved with age, some children may follow a relapsing and persistent course. The underlying decisive early-life factor is not yet known. An increasing number of studies have shown an association between eczema and skin microbiome fluctuations. Evidence has revealed an association between gut microbiome and persistence of eczema, but currently limited data are available in terms of skin microbiome. Objectives This prospective study aimed to investigate whether skin microbiome profiles differ between patients with transient eczema and those with persistent eczema. Methods We followed up 120 Chinese infants living in Hong Kong from childbirth to 2 years old. At 6, 12 and 24 months, participants attended clinic visits in our hospital and eczema was diagnosed based on Hanifin and Rajka criteria by paediatricians. Based on physician diagnoses, participants were further classified into transient eczema group, persistent eczema group and never eczema group. Skin microbes at left antecubital fossa (LAF) were serially sampled by flocked swabs at 1, 6 and 12 months. Skin microbiome data was later generated by 16S rRNA sequencing. A recently developed statistical method for microbiome called Analysis of Compositions of Microbiomes with Bias Correction (ANCOM-BC) was used to assess differentially abundant taxa among groups. Results In our birth cohort, 60/119 (50%) participants are male, and 28/119 (24%) were born by caesarean section. Forty-three out of 120 (36%) participants’ mothers have history of allergies. Forty-six out of 101 (46%) participants developed eczema within 6 months, and 33/97 (34%) presented with active eczema at 12 months. At 24 months, 18/100 (18%) participants still had active eczema. During the study period in total 297 skin swab samples from LAF were collected. Alpha diversity represented by Shannon and Simpson indices significantly increased from 1 month to 6 months (p=0.001 and p=0.004 respectively). Relative abundance of Staphylococcus and Corynebacterium progressively decreased from 1 month to 6 months (β =-1.95, pConclusions Establishment of skin microbiome is highly dynamic in early life. Our results do not support that early-life microbiota at left antecubital fossa is associated with eczema persistence during infancy. (Funding: Health and Medical Research Fund 06170466)