MiR-199-3p-Dnmt3a-STAT3 signalling pathway in ovalbumin-induced allergic rhinitis

What is the central question of this study? What is the mechanism of DNA methylation in allergic rhinitis? What is the main finding and its importance? A miR-199-3p-Dnmt3a-STAT3 signalling pathway is involved in ovalbumin-induced allergic rhinitis, and miR-199-3p antagomir can relieve the symptoms in the mouse model.

Recent research has pointed out the involvement of epigenetic modifications in allergic rhinitis (AR), especially DNA methylation. However, the detailed mechanism has remained largely uncovered. We used ovalbumin (OVA) to induce AR in mouse, and behaviour scores were used to confirm its successful establishment. Histamine and other inflammatory factors were detected to further verify success of the model. Real-time PCR was employed to identify the overexpression of miR-199-3p and subsequent down-regulation of DNA methyltransferase 3a (Dnmt3a). Western blotting was utilized to detect Dnmt3a and signal transducer and activator of transcription 3 (STAT3) at the protein level. Bisulfite sequencing PCR was applied to reveal the methylation status of the Stat3 promoter region. A dual-reporter assay was used to confirm the direct targeting of miR-199-3p on the Dnmt3a mRNA and an antagomir specific to miR-199-3p was injected to rescue the symptoms of AR. The AR model was successfully established in mouse and confirmed by both behaviour and molecular markers. We also found lowered expression of Dnmt3a and consecutive hypomethylation of Stat3 promoter and elevated expression of STAT3, which then led to overexpression of IgE and other inflammatory factors. MicroRNAs that worked on the Dnmt3a 3'-untranslated region were predicted and then verified by dual-reporter assay. Finally injection of a miR-199-3p antagomir successfully attenuated the symptoms of AR. We propose that the miR-199-3p-Dnmt3a-STAT3 signalling pathway is involved in OVA-induced AR.