The Effect Of MiR-221 On Airway Inflammation And Airway Remodeling In OVA-induced Asthmatic Mice

ObjectiveTo investigate the effects of miR-221 on airway inflammation and airway remodeling in ovalbumin-induced murine asthma model.Methods 1)Airway smooth muscle cells were transfected with inhibitor NC or miR-221 inhibitor and the transfection efficiency of miR-221 inhibitor was verified by RT-qPCR.Western Blot was used to detect the expression level of extracellular matrix such as type I collagen and type III collagen.2)The mice were randomly divided into 4 groups: normal control group(GFP-NS),miR-221 downregulation group(miR-221 ↓-NS),OVA group(GFP-OVA),OVA and miR-221 downregulation group(miR-221 ↓-OVA).The asthmatic mice model was constructed by OVA sensitization and challenge and they were infected with AAV6 by tracheal intubation.Then the changes of miR-221 expression was detected by RT-qPCR.The pulmonary function at basal condition and different concentrations of methacholine(Mech)were measured by AniRes2005 lung function system,including the changes of Ri,Re and Cldyn.3)The number of total cells and the ratio of eosinophils to total cells in BALF were assessed.And the levels of IL-6 and TNF-α in BALF and serum were also detected by ELISA.4)HE staining of lung tissues of mice was conducted to observe inflammatory cells infiltration and airway wall thickness.Lung tissues were also performed PAS staining and Masson staining to observe airway mucus secretion,proliferation of goblet cells and collagen fibers hyperplasia.5)Western Blot technique was performed to detect the expression of extracellular matrix of lung tissues.Results 1)The inhibition of miR-221 decreased the expression level of type I collagen and type Ⅲ collagen in ASMCs.2)The asthmatic mice model can be successfully established.Compared with OVA group,inhibition of miR-221 could reduce the changes of lung function,mainly including reducing inspiratory resistance,expiratory resistance and increasing dynamic lung compliance.3)Compared with the OVA group,the inhibition of miR-221 could reduce the total cell counts and the ratio of EOS in BALF.It could also decrease the concentration of IL-6 and TNF-α in BALF and serum.4)Down-regulation of miR-221 reduced airway inflammation infiltration in asthmatic mice and the thickness of airway wall.It could also decrease airway epithelial goblet cell hyperplasia and mucus secretion.At the same time,it could reduce the expression of MUC5 AC and collagen fibrosis.5)Down-regulation of miR-221 reduced the expression of extracellular matrix such as type I and type III collagen in lung tissues of asthmatic mice.Conclusion Downregulation of miR-221 could reduce the expression of extracellular matrix in ASMCs.Inhibition of miR-221 could also suppress airway inflammation and airway remodeling in asthmatic mice induced by OVA.