Protective effect of carbon monoxide pre-conditioning on LPS-induced endothelial cell stress

Abstract

Increasing evidence indicates that carbon monoxide (CO) may protect against several diseases including sepsis. The ability of CO pre-treatment to provide good pre-conditioning against lipopolysaccharide (LPS)-induced injury was tested using an in vitro model of primary culture of porcine aortic endothelial cells (pAEC). pAEC were exposed to CO (250 ppm) or air for 1 h prior to the addition of LPS (10 microg/ml). Hsp70, HO-1, and Egr-1 protein levels were determined as well as vascular endothelial growth factor (VEGF) secretion after 4, 7, and 15 h. The effect of CO on LPS-induced apoptosis was also detected at 15 h. CO pre-treatment before the addition of LPS, significantly reduced LPS-induced apoptosis. LPS induced an increase in the level of VEGF in culture media after 7 and 15 h, and a larger increase was detected in CO pre-treated cells. In addition, CO pre-treatment reduced LPS-induced Hsp70, HO-1, and Egr-1 protein expression. In conclusion, CO treatment seems to provide a good pre-conditioning for the prevention of LPS-induced endothelial injury.

Fig. 1

Effect of CO pre-treatment on LPS-induced apoptosis. Data represent the mean ± SEM of three replicates. Different letters above bars indicate statistically significant differences (P < 0.05). CTR standard culture condition, CO CO pre-treatment (1 h) + standard culture condition (15 h), LPS LPS treatment (15 h), LPS + CO CO pre-treatment (1 h) + LPS treatment (15 h)

Fig. 2

Effect of CO pre-treatment on protein expression. a VEGF secretion in culture medium (pg/ml). b–d HO-1, Hsp70, Egr-1 expression (AU arbitrary unit). Data are presented as the mean ± SEM of three replicates. Capital letters above bars indicate statistically significant differences (P < 0.05) within treatment during the time. Small letters above bars indicate statistically significant differences (P < 0.05) among treatment at the same time point. CTR standard culture condition, CO CO pre-treatment (1 h) + standard culture condition (4, 7, and 15 h), LPS LPS treatment (4, 7, and 15 h), LPS + CO CO pre-treatment (1 h) + LPS treatment (4, 7, and 15 h)