MiRNA-21 Regulates Bronchial Epithelial Cell Proliferation by Activating Tgfβ1/Smad Signaling Pathway and Its Correlation with Asthma Severity in Children

This research was designed to probe into the role of miRNA-21 in the pathogenesis of child-hood asthma and its correlation with the severity. Methods: Fifty-four children with bronchial asthma admitted to the Third Affiliated Hospital of Qiqihar Med-ical University from Jun 2018 to Dec 2019 were included. Forty nine healthy children underwent physical ex-amination at this time period were also enrolled. The miR-21 expression in peripheral blood serum was ana-lyzed by qRT-PCR. The relationship between the expression and severity of asthma in children was explored by Spearman correlation analysis and ROC curve. Bronchial epithelial cell lines were cultured in vitro and di-vided into blank control group, negative control group and miR-21 inhibition and activation group. The chang-es of cell proliferation after treatment were detected by CCK-8 test in different groups. The expression of TGF-β1/Smad signaling pathway protein in cells was assessed by Western blot (WB). Results: Compared with that of healthy children, the miR-21 expression in peripheral blood serum of asthmat-ic children was higher (P<0.001). MiR-21 expression was positively correlated with the severity of illness (r=0.853, P<0.001). The results of cell experiments in vitro signified that miR-21 can promote the proliferation of bronchial epithelial cells, and may be involved in regulating the expression of TGF-β1/ Smad3 signaling pathway, thus affecting cell proliferation. Conclusion: miRNA-21 regulates the proliferation of bronchial epithelial cells by activating TGFβ1/Smad signaling pathway. an‎d it is positively correlated with the severity of asthma in children.