The Effect of Bronchial Allergen Challenge on Blood Eosinophil Subtypes-Specific miRNAs Expression in Allergic Asthma

Introduction: Acute episode of allergic asthma (AA) is associated with increased blood and airway eosinophilia. miRNAs act as regulators of gene expression and we hypothesized that distinct blood lung-resident-like eosinophils (rEOS-like) and inflammatory-like eosinophils (iEOS-like) biological properties are related with subtype-specific miRNAs expression in acute AA Aim: To investigate the effect of bronchial allergen challenge (BAC) with D.pteronyssinus on miR-185-5p, miR-1290, miR-146b-5p, miR-320b, miR-21-5p expression in blood rEOS-like and iEOS-like cells in AA patients Methods: We studied 9 steroid-naïve AA patients before and 24h after BAC with D.pteronyssinus, which imitates acute asthma episode. Total blood eosinophils were isolated by high-density centrifugation and magnetic separation, phenotyping – with magnetic beads conjugated antibodies against L-selectin. miRNA expression in blood eosinophils and plasma samples was measured by RT-qPCR analysis Results: The study showed that BAC did not affect the miRNA expression in rEOS-like cells but upregulated the miR-1290 by 1.95, miR-21-5p by 3.25, and downregulated miR-146b-5p expression by 5.54 folds in iEOS-like cells (p<0.05). Analysis of miRNA in the blood plasma of asthmatic patients showed decreased circulating miR-1290 and miR-21-5p levels after BAC by 6.56 and 17.03 folds, respectively (p<0.05). BAC had no significant effect on miR-146b-5p in plasma and miR-185-5p and miR-320b expression neither in eosinophils nor in plasma (p>0.05) Conclusions: The BAC affects only iEOS-like cells’ miRNAs expression; however, these eosinophil subtype-specific miRNAs cannot be related to its plasma levels in AA patients