Infantile atopic dermatitis: Serum vitamin D, zinc and TARC levels and their relationship with disease phenotype and severity

Background: Several markers that influence the clinical course of atopic dermatitis (AD) have been investigated so far. Thymus and activation regulated chemokine (TARC) – a Th2-related cytokine – increase in various atopic diseases. It has been shown that vitamin D affects Treg cells and immune responses. Zinc as an essential trace element for cell–cell interactions, cellular differentiation, and proliferation. However, the effect of these markers on infantile AD and disease severity are mostly unknown.Objective: The aim of this study was to investigate the relationship between TARC, vitamin D, zinc levels, and the disease severity in infants with AD.Method: AD patients (n = 160) with age and sex that matched healthy controls (n = 79) were included in the study. The diagnosis of AD was made based on the Hanifin–Rajka criteria. The objective SCORAD index was used for the assessment of disease severity.Results: A total of 160 patients (male 71.9%) with AD were included in the study. The median age of onset of symptoms was 2 (1.0–3.5) months. The lesions initially started on face 76.9%, neck 6.9%, extremities 7.5%, and body 8.8%. Nearly 40% of the patients were found to be atopic. Food allergy was found in 39.4%. The median of objective SCORAD index was 27.5 (17.5–40) in the study group. The TARC levels of AD patients were higher than control group [1803 pg/ml (1006– 3123) vs 709 pg/ml (504–1147), p < 0.001] There was a significant correlation between objective SCORAD scores and TARC values in subjects with AD (r = 0.363, p < 0.001). As the severity of AD increased, vitamin D levels decreased (p for trend 0.015) and TARC values increased (p for trend < 0.001). Serum zinc levels did not change with the severity of the disease. The presence of atopy did not have an influence on serum TARC, zinc, and vitamin D levels.Conclusion: In infants with AD, disease severity is positively related with TARC levels; and inversely proportional to vitamin D levels. TARC levels differ between patients and healthy controls. The presence of atopy has not been shown to affect these markers.