Vitamin D, cytokine profiles, and disease severity in infants with atopic dermatitis: a single centre, cross-sectional study

Introduction
Atopic dermatitis (AD) is an immune-mediated inflammatory skin disease and generally develops in infancy. Studies evaluating the role of vitamin D in immune mechanims in AD showed varying results.

Aim
To assess the association between serum vitamin D, cytokine profiles, and disease severity in infants with AD.

Material and methods
A cross-sectional study was conducted on infants aged 0–12 months with AD in the Paediatric Allergy and Immunology Department, Saiful Anwar Hospital, Indonesia. The disease severity was assessed by the Scoring of Atopic Dermatitis (SCORAD) index. Blood was drawn to evaluate the total eosinophil count (TEC), total immunoglobulin E (tIgE), 25-hydroxyvitamin D (25(OH)D), interleukin-4 (IL-4), IL-17A, and IL-22 levels.

Results
This study enrolled 36 infants including 19 with mild AD and 17 with moderate AD. Vitamin D deficiency and insufficiency were found in 18 (50%) and 9 (25%) subjects, respectively. The mean 25(OH)D level was lower and the mean IL-4, IL-17A, and IL-22 levels were higher in the moderate AD group than in the mild AD group (p < 0.05). A lower level of 25(OH)D was associated with a higher level of IL-17A (r = –0.315, p = 0.041). The SCORAD index was negatively correlated with 25(OH)D (r = –0.714, p < 0.001) and positively correlated with IL-17A (r = 0.522, p = 0.001) and IL-22 (r = 0.612, p < 0.001) but not IL-4 (r = 0.325, p = 0.053).

Conclusions
There was a high prevalence of vitamin D deficiency and insufficiency in infants with AD, and a low vitamin D level was correlated with the severity of AD, dependently on IL-17A.