The aim of this study was to investigate the expression profiles of microRNAs (miRNAs) in pediatric asthma and to determine candidate miRNAs responsible for the pathogenesis of this disease. Microarrays were used to detect the differences in the miRNA expression levels between asthmatic children and controls. Airway inflammation was evaluated by cell counting and tissue biopsy in an ovalbumin (OVA)-induced murine asthma model. Real-time polymerase chain reaction (PCR) was used to verify the differentially expressed miRNAs. The targets of the identified miRNAs were analyzed by bioinformatic analysis. The sprouty-related protein with an EVH1 domain-2 (Spred-2) protein content was assessed by western blotting. Differences were observed in the expression of miRNAs between the asthmatic children and controls. Upregulation of miRNA-221 and miRNA-485-3p in pediatric asthmatics and murine asthma models were verified by real-time PCR. Spred-2, a predicted target of miRNA-221 and miRNA-485-3p, was downregulated in murine asthma models. Upregulation of miRNA-221 and miRNA-485-3p may regulate the pathogenesis of asthma.

This study investigated the expression of miRNA-221 in asthmatics in order to determine whether miRNA-221 plays a role in the development of asthma. Real-time PCR was used to detect the miRNA-221 in both asthmatic and control subjects. In addition, airway inflammation was evaluated by cell counting and tissue biopsy in the OVA-induced murine asthma model. miRNA-221 was differentially expressed in asthmatics and control subjects, and miRNA-221 blockade resulted in a reduction of airway inflammation in the OVA-induced murine asthma model. We conclude that miRNA-221 participates in the pathogenesis of asthma and that inhibition of miRNA-221 suppresses airway inflammation in asthmatics.