Mechanism Of MiRNA-224 And CDK9 In The Development Of Allergic Rhinitis

Background: Allergic rhinitis(AR)is a complex allergic disease with multiple genes involved in Rhinology.It is one of the most common allergic diseases.The reported prevalence rate of AR in different regions of mainland China is 4%-38%,and there are large differences between different urban and rural areas.In recent years,there has been a clear upward trend.AR seriously affects the quality of life of patients.It also creates a huge medical and social burden.The pathogenesis is complicated.It is believed that there are many kinds of immunocompetent cells,pro-inflammatory cells and cytokines participated,yet there is no satisfactory treatment now.With the gradual deepening of allergic molecular pathological research,there are differential expressions of various gene sequences in the pathogenesis of allergic rhinitis,including long-chain non-coding RNA(lnc RNA),micro RNA(miRNA)and other variety of RNAs.Micro RNA(miRNA)is a kind of recently identified small single chain RNA which plays a significant role in regulation of gene expression(especially in cell growth,differentiation,function dominance).It is an important post-transcriptional regulation of protein-coding gene expression.As multiple genes involved in allergic rhinitis,miRNAs may contribute a lot.Objective:We aimed to explore the regulatory effects of micro RNA-224(miR-224)and its potential target gene — — cyclin dependent kinase 9(CDK9)in the pathological process of allergic rhinitis.Methods: The study was designed to investigate the utility of miR-224,which was differentially expressed in nasal mucosa of AR patients,and its predicted target gene CDK9,which was screened by using bioinformatics prediction software,and verifying by dual luciferase reporter gene detection,in AR animal models.The AR animal model was established in C57 mice by intraperitoneal sensitization and intranasal challenge with ovalbumin(OVA).Mi R-224 agomir was then intranasally administrated to mice after OVA challenge for another 12 days in four separate interventions.The symptoms of sneezing and nasal rubbing were recorded after the last OVA challenge.Nasal mucosa tissues and serum were collected.CDK9 expression,proinflammatory cytokines(IL-4,IL-6,IL-18)levels,serum Ig E and Histamine concentration were measured by RT-PCR,ELISA or western blotting,respectively.Histopathologic changes were evaluated using Hematoxylin-eosin and immunofluorescence staining.Results: The dual luciferase reporter gene test verified that CDK9 is the target gene of miR-224,which is consistent with the results of the bioinformatics prediction software.We detected the expression levels of miR-224 and CDK9 in the nasal mucosa of AR animal models.We found that the miR-224 expression was evidently downregulated,while that of CDK9 was upregulated,which was significantly different from the control group.Even after the intervention with dexamethasone,the expression of both showed a significant negative correlation.Upregulation of miR-224 by using miR-224 agomir markedly reduced the frequencies of nasal rubbing and sneezing,the expression of CDK9,the levels of cytokines(IL-4,IL-6),and the concentration of Ig E and HA.Moreover,miR-224 also appeared to attenuate the infiltration of inflammatory cells and hypersecretion of glands in the nasal mucosa.The number of CDK9,which distributed under the mucosa,especially in the submucosa interstitial tissue,was significantly reduced.The allergic symptoms were eased.Conclusion: The present studies showed that miR-224 may affect the pathogenesis of AR by targeting CDK9(negative regulation).It provides new insights into the mechanism of miR-224 in allergic rhinitis,implies a novel potential therapeutic target for the treatment of AR.