Exploratory analysis of circulating miRNA-100 and its association with eosinophilia in pediatric allergic rhinitis.

Introduction: Allergic rhinitis (AR) is a chronic inflammatory disorder of the upper airways characterized by a Th2-skewed immune response, elevated immunoglobulin E (IgE) levels, and eosinophilia. Increasing evidence suggests that microRNAs (miRNAs) may contribute to the regulation of immune pathways in AR; however, their role in pediatric populations remains insufficiently understood. Aim: The aim of this exploratory study was to evaluate serum expression of miRNA-100, miRNA-155, and miRNA-224 in children with AR and to assess their associations with immunological and clinical parameters. Materials and methods: A total of 21 children were included (12 with AR and 9 non-atopic controls). Serum levels of selected miRNAs, cytokines (IL-4, IL-5, IL-6, IL-10, IL-13), eosinophil counts, and total IgE were analyzed. Results: MiRNA-100 expression was higher in the AR group compared with controls; however, this difference did not reach statistical significance (p = 0.051). No significant differences were observed for miRNA-155 or miRNA-224. In unadjusted analyses, correlations between miRNA-100 and eosinophil parameters were not statistically significant. In partial correlation analysis adjusted for age and sex, a moderate association between miRNA-100 and absolute eosinophil count was observed (rho = 0.498; p = 0.042). Among cytokines, only IL-10 levels were significantly lower in the AR group, while a substantial proportion of measurements for other cytokines were below the detection limit, limiting interpretability. Conclusions: Given the small sample size and lack of statistical significance in primary comparisons, these findings should be considered preliminary and hypothesis- generating. The observed association between miRNA-100 and eosinophilia may warrant further investigation in larger, well-characterized cohorts.