Respiratory syncytial virus promotes apoptosis and expression of inflammatory factors in bronchial epithelial cells by regulating miR-409-3p/SIRT1 pathway

Abstract

Objective To explore the effect of respiratory syncytial virus (RSV) on the apoptosis and the expression of inflammatory factors in human bronchial epithelial cells (HBECs), and investigate its possible mechanisms. Methods In vitro cultured HBECs were transfected with miR-409-3p inhibitor, overexpression vector of silent information regulator 1 (SIRT1) along, or co-transfected with miR-409-3p inhibitor and SIRT1 small interfering RNA (siRNA), respectively. After RSV infection, RT-qPCR was used to detect the expression levels of miR-409-3p and SIRT1 in the transfected cells. Cell counting kit-8 (CCK-8) assay and flow cytometry were performed to determine cell proliferation as well as cell apoptosis. Western blotting was also adopted to verify the expression of Ki-67, p21, Bcl-2 and Bax. In addition, corresponding reagent testing kits were used to detect the contents of IL-6 and TNF-α in culture supernatant. Finally, the regulatory relationship between SIRT1 and miR-409-3p was verified by the dual luciferase reporter assay. Results RSV infection promoted the expression of miR-409-3p (P < 0.05), inhibited that of SIRT1 (P < 0.05), decreased cell proliferation and protein expression of Ki-67 and Bcl2 (P < 0.05), and promoted cell apoptosis and protein expression of p21 and Bax and contents of IL-6 and TNF-α (P < 0.05) in HBECs cells. Silencing miR-409-3p or overexpressing SIRT1 resulted in the enhanced the proliferation activity and the protein expression of Ki-67 and Bcl2 in RSV-infected HBECs cells (P < 0.05), but decreased apoptotic rate, protein expression of p21 and Bax, and contents of IL-6 and TNF-α (P < 0.05). miR-409-3p showed a negatively targeted regulation to SIRT1 expression. Silencing SIRT1 reversed the effects of silenced miR-409-3p on the proliferation and apoptosis of RSV-infected HBECs as well as on the expression of inflammatory factors IL-6 and TNF-α (P < 0.05). Conclusion RSV promotes the apoptosis and the expression of inflammatory factors in bronchial epithelial cells by regulating miR-409-3p/SIRT1 pathway.

Keywords

• bronchial epithelial cells
• respiratory syncytial virus
• mir-409-3p
• sirt1
• apoptosis
• inflammatory factors