The dose-effect and time-effect on the expression of human β-defensin-3 in human bronchial epithelial cells induced by LPS

Objective To observe the mRNA expression of human β-defensin-3 (hBD-3) at different time points after being induced by lipopolysaccharide (LPS) of different concentration in human bronchial epithelial cells (HBEC),and explore the role of hBD-3 in respiratory tract infection and the dose-effect and time-effect on the expression of hBD-3. Methods Human bronchial epithelial cells were stimulated with different concentrations of LPS (0.01,0.1,1,10 mg/L). The mRNA expression of hBD-3 at different time points (1,2,4,8 h) was determined by RT-PCR. Four hours after being stimulated by 0.1 mg/L LPS,the expression of hBD-3 protein was investigated by immunocytochemical technique. Results The brown cationic granules (the expression of the hBD-3 protein) were seen apparently in the cytoplasm of HBECs at 4 hours after stimulation by 0.1 mg/L LPS. After stimulation by different concentrations of LPS,the expression of hBD-3 mRNA in normal human bronchial epithelial cells at the same time point increased with the concentration of LPS. Significant difference was found between different concentrations (P0.01). After stimulation by the same concentration of LPS,the expression of hBD-3 mRNA in normal human bronchial epithelial cells increased with the stimulation duration. The difference between different time points was statistically significant (P0.01). Conclusions Expression of hBD-3 is present in the cytoplasm of human bronchial epithelial cells. After being stimulated by LPS,the expression of hBD-3 is increased. LPS can induce the expression of hBD-3 in a dose and time dependent manner within a certain range. The expression of hBD-3 may play an initial defensive role against bacterial invasion.