MiR-224 ameliorates inflammation and symptoms in mouse model of allergic rhinitis by targeting CDK9.

OBJECTIVES: To explore the regulatory effects of microRNA (miRNA)-224 and its potential target gene, cyclin dependent kinase 9 (CDK9), in the pathological process of allergic rhinitis (AR). METHODS: To investigate the role of miR-224 and CDK9, it was screened by bioinformatics prediction software and verified by dual-luciferase reporter assay. The mouse model of AR was established by ovalbumin (OVA).The animal models were intervened with miR-224 agomir, negative control agomir, and saline respectively. The symptoms of sneezing and nasal rubbing were recorded. The expressions of miR224, CDK9, and cytokines in the nasal mucosa of different groups were analyzed by rt-PCR or western blotting. Enzyme-linked immunoassay (ELISA) was used to evaluate the levels of IgE and Histamine (HA) in the serum. The infiltration of inflammatory cells in the nasal mucosa was studied by immunohistochemistry. The expression and distribution of CDK9 in the nasal mucosa of mice were revealed by immunofluorescence. RESULTS: In the nasal mucosa of the animal models, the level of miR-224 was downregulated, while that of CDK9 was upregulated. The upregulation of miR-224 by miR-224 agomir reduced the frequencies of nasal rubbing and sneezing, the expression of CDK9, the levels of cytokines, and the concentrations of IgE and HA. Moreover, miR-224 appeared to attenuate the infiltration of inflammatory cells and hypersecretion of glands in the nasal mucosa. The expression of CDK9, which was distributed under the mucosa, especially in the submucosa interstitial tissue, was significantly reduced. CONCLUSION: MiR-224 affected the pathogenesis of AR by targeting CDK9. It proves that miR-224 could be a novel potential therapeutic target for AR.