Exploratory analyses of biomarkers in blood and stratum corneum in patients with atopic dermatitis

Background: The pathogenesis of atopic dermatitis (AD) involves various mediators, including cytokines and chemokines, which are produced by immune cells, such as dendritic cells and lymphocytes, and non-immune cells, such as epidermal cells. Several mediators, including thymus and activation-regulated chemokine (TARC), are used as biomarkers for AD severity and activity. However, additional local and systemic biomarkers of AD are required. Methods: This study will include 10 male patients with AD and 5 healthy adult males (age range: 20-80 years). The Eczema Area and Severity Index will be used to objectively evaluate the clinical findings. In addition, the severity of eruptions will be assessed on a 5-point scale by scoring symptoms (erythema, edema/papules, oozing/crusting, excoriation, lichenification, and xerosis), and the total intensity will be calculated by adding the symptom scores together. Subjective symptoms will be assessed using a peak pruritus numerical rating scale. Laboratory tests, including measurements of peripheral eosinophil count and serum total immunoglobulin E, TARC, and lactate dehydrogenase levels, will be performed. Using blood samples and extracts of stratum corneum samples obtained by tape stripping, we will conduct an exploratory analysis of protein expression using an antibody array to identify mediators whose levels are significantly altered in patients with AD. After 4 to 8 weeks, blood samples and stratum corneum samples will be collected again from AD patients. Moreover, we will examine whether the candidate proteins can be quantified using enzyme-linked immunosorbent assays. Discussion: This is an important study exploring potential local and systemic biomarkers of AD. The results of this study will be clinically meaningful for the discovery of new biomarkers for diagnosing and assessing the severity of AD.