Correlation between serum thymus and activation-regulated chemokine levels and stratum corneum barrier function in healthy individuals and patients with mild atopic dermatitis

Background Serum thymus and activation-regulated chemokine (TARC) levels closely reflect the disease activity of atopic dermatitis (AD). AD is characterized by impaired epidermal barrier function and atopic dry skin. However, dry skin is also a very common problem in healthy individuals. Objective To investigate the relationship between serum TARC levels and epidermal barrier function in healthy subjects and patients with mild AD. Methods This study included 2 groups, 121 healthy subjects (healthy group) and 66 patients with mild AD (mild AD group). Barrier function was assessed by transepidermal water loss (TEWL) and stratum corneum hydration (SCH). Results Significantly elevated serum TARC levels and TEWL values and significantly decreased SCH values were detected in the mild AD group compared to those in the healthy group. In the mild AD group, serum TARC levels were significantly correlated with TEWL values and were inversely correlated with SCH values. Importantly, serum TARC levels were also inversely correlated with SCH values in the healthy controls. TEWL values in the healthy group tended to be correlated with TARC levels but did not reach statistical significance. Conclusion Together with TEWL and SCH, serum TARC level is a useful biomarker, reflecting impairment of epidermal function in AD patients as well as healthy subjects.