Role of mechanical stretching and lipopolysaccharide in early apoptosis and IL-8 of alveolar epithelial type II cells A549

OBJECTIVE@#To investigate the effects of mechanical stretching and lipopolysaccharide (LPS) on the early apoptosis and IL-8 production of alveolar epithelial type II cells A549.@*METHODS@#The experimental matrix consisted of three integrated studies. In the first study, A549 cells were subjected to different stretching strain frequency and duration time to see the effects on the early apoptosis. In the second study, A549 cells were subjected to mechanical stretch (15% 4 h, 0.5 Hz) and LPS (1 or 100 ng/mL) to see whether mechanical strain and LPS also have an addictive effect on the early apoptosis. In the third study to investigate whether this addictive effect could be induced by LPS and mechanical stretch on IL-8 production, A549 cells were subjected to LPS (100 ng/mL) and mechanical strain (15%, 0.5 Hz, 4 h). Real time PCR and enzyme linked immunosorbent assay were used to measure mRNA and protein level of IL-8. The early apoptosis was detected by flow cytometry.@*RESULTS@#Mechanical stretch induced the early apoptosis in a force and frequency and time-dependent manner. In the presence of LPS, mechanical stretch enhanced LPS-induced early apoptosis, especially in 100 ng/mL LPS group compared with 1 ng/mL LPS and the control group. Mechanical stretch increased IL-8 production and enhanced LPS-induced IL-8 screation both in mRNA and protein levels.@*CONCLUSIONS@#Mechanical stretch can induce the early apoptosis and IL-8 secretion. Mechanical stretch and LPS have an addictive effect on the early apoptosis and IL-8 production in alveolar type 2 cells, which is one of the mechanisms of ventilator-induced lung injury.

Early apoptosis induced by mechanical stretch in human alveolar type Ⅱ epithelial cells / 上海第二医科大学学报

Objective To investigate the apoptosis response to mechanical stretch in human alveolar type Ⅱ epithelial cells A549.Methods First,A549 cells were given different stretch(0%,5%,15%,30%) at frequency of 0.5 Hz for 4 h.Then,A549 cells were stretched for different periods(0 h,2 h,4 h,8 h) at stretch 15%,0.5 Hz.Last,A549 cells were stretched for different frequency(0 Hz,0.2 Hz,0.5 Hz and 1 Hz) at stretch 15% for 4 h.The early apoptosis was detected by flow cytometry. Results A549 cells submitted to cyclic stretch caused the early apoptosis in a time-,stretch-and frequency-dependent manner.In details,at 0.5 Hz and 4 h stretch-dependence occurred,at 15% stretch and 0.5 Hz time-dependence occurred,and at 15% stretch and 4 h frequency-dependence occurred. Conclusion Mechanical stretch can induce the early apoptosis in human alveolar type Ⅱ epithelial cells A549,which may be one of the mechanisms of ventilator-induced lung injury.