Effects of mechanical stretch on the expression of human beta-defensin-3 in alveolar epithelial cells elicited by interferon- gamma / 中华急诊医学杂志

ABSTRACT

Objective To study the effect of mechanical stretch on the expression of human beta-defensin-3 (HBD-3) in alveolar epithelial cells(A549 cells) elicited by interferon-gamma(IFN-γ) and to investigate the role of HBD-3 in the pathogenesis of ventilator-associated pneumonia (VAP) . Method A549 cells cultured in vitro were treated with mechanical stretch (group S), 10 ng/ml IFN-γ (group I) ,and 10 ng/ml IFN-γ with mechanical stretch (group IS), respectively. Cells without treatment served as controls (group C). Cells were stretched by 20% amplitude of stretch at 30 cycles/mm by Flexercell-4000[TM]Unit for 2 h, 4 h, and 6 hours. The HBD-3 mRNA expression was determined by real-time RT-PCR after treatment. After 6 hours, treatment, cells were cultured for 24 hours and the expression of HBD-3 was examined by laser scanning confocal microscope. The experimental data were statistically analyzed by using one-way ANOVA analysis and q-test. Results The expression of HBD-3 mRNA in A549 cells could not significantly be changed by mechanical stretch alone. Compared with group C,the HBD-3 mRNA expression after treatment with 10 ng/ml IFN-γ for 2 hours,4 hours and 6 hours increased significantly by (2.63 C,the HBD-3 mRNA expression after treatment with 10 ng/ml IFN-γ and mechanical stretch for 2 hours,4 hours and 6 hours increased by (1.54 were significantly lower than those in group I (P < 0.01). The HBD-3 expression in group IS after mechanical stretch for 6 significantly different from than in group C. Conclusions Mechanical stretch can significantly suppress the up-regulation of HBD-3 in alveolar epithelial cells elicited by IFN-γ, and this may be one of the explaina-tions that patients under mechanical ventilatiori(MV) have a higher risk of VAP.