Elevated Serum Levels of miRNA-155 in Children with Atopic Dermatitis: A Potential Biomarker of Disease

Atopic dermatitis (AD) is the most common inflammatory skin disease in the pediatric population. In recent years, the role of microRNAs in inflammatory and immunological mechanisms as specific biomarkers of AD has received growing attention. The aim of the present study was a quantitative assessment of serum expression levels of miR-100, miR-224 and miR-155 in children with AD compared with healthy peers, and an analysis of their potential associations with clinical disease phenotype, severity of skin lesions (SCORAD), cytokine profile, immunological parameters and the presence of concomitant allergic diseases. The study included 12 children with AD and 9 healthy children. Selected miRNAs were isolated from serum, followed by reverse transcription using universal primers and quantification by qRT-PCR. Children with AD exhibited significantly higher expression levels of miR-155 compared with controls (<i>p</i> = 0.003). No statistically significant differences were observed for miR-100 and miR-224. miR-100 expression was significantly higher in children with a positive history of inhalant allergy compared with those without such a diagnosis (<i>p</i> = 0.014). A positive correlation was observed between miR-100 levels and the percentage of eosinophils (r = 0.599; <i>p</i> = 0.052) as well as absolute eosinophil count (r = 0.600; <i>p</i> = 0.051). MiR-155 is significantly upregulated in children with AD suggesting it as a candidate biomarker worthy of further investigation in larger cohorts. Although miR-100 did not differentiate the groups, its correlation with eosinophilia and inhalant allergy suggests a role in disease phenotyping.