Effect of NaNO2 on oxidative damage in house dust mite pretreated airway epithelial cells and its underlying mechanism

Abstract

Objective To investigate the effects and underlying mechanisms of NaNO2 on oxidative damage in human bronchial epithelial cells pretreated with house dust mite (HDM). Methods Human bronchial epithelial cell line 16HBE were pretreated with HDM and then exposed to varying concentrations of NaNO2.Cell viability was assessed using CCK-8 assay to determine the optimal concentration and treatment duration of NaNO2.Then 16HBE cells were randomly divided into normal control group, HDM group (pretreated with HDM), and NaNO2 group (pretreated with HDM followed by NaNO2 exposure).The expression of Krüppel-like transcription factors 2(KLF2), hypoxia-inducible factor-1α(HIF-1α), and Notch1 at protein and mRNA levels in each group were measured by Western blotting and RT-PCR, respectively.The contents of the inflammatory cytokines IL-6 and TNF-α were assessed using ELISA.The production of reactive oxygen species (ROS) were measured using a fluorescence probe detection.The contents of malondialdehyde (MDA) and glutathione (GSH) were quantified by micro-methods. Results CCK-8 assay determined that the optimal intervention of NaNO2 was 500 μmol/L for 24 h.Compared with the normal control group, the HDM group showed reduced protein and mRNA expression of KLF2, but increased protein and mRNA (P < 0.01) expression of HIF-1α, and Notch1 at protein (P < 0.05) and mRNA levels, elevated production of ROS (P < 0.01), and increased contents of MDA, TNF-α, and IL-6, with a decrease in GSH content (P < 0.05).Compared with the HDM group, the NaNO2 group exhibited a significant reduction in KLF2 protein and mRNA levels, increases in HIF-1α protein and mRNA levels, Notch1 protein (P < 0.05) and mRNA levels, elevated ROS content (P < 0.01), and significantly increased contents of MDA, TNF-α(P < 0.001), and IL-6, with a notable decrease in GSH content (P < 0.05). Conclusion NaNO2 may exacerbate HDM-induced oxidative stress injury in human bronchial epithelial cells by regulating the expression of KLF2.

Keywords

• oxidative stress
• klf2
• airway epithelial cells
• asthma
• nitrogen oxides