TRAIL inhibits oxidative stress in human aortic endothelial cells exposed to pro-inflammatory stimuli

Abstract

Studies suggest that tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has vasoprotective potential, as low levels of TRAIL cause accelerated vascular calcification, whereas exogenous TRAIL administration exhibits anti-atherosclerotic activity. The mechanism of TRAIL-mediated vasoprotection remains unclear. We studied the effects of TRAIL (100 ng/ml) on human aortic endothelial cells (HAECs) exposed to pro-atherogenic conditions; (a) oscillatory shear stress (±10 dynes/cm² ) using the ibidi µ-slide fluidic system; (b) pro-inflammatory injury, that is, tumor necrosis factor alpha (TNF-α, 100 ng/ml) and hyperglycemia (30 mM d-glucose). End-points examined included inflammatory gene expression and reactive oxygen species (ROS) formation. TRAIL shifted the net gene expression toward an antioxidant phenotype in HAECs exposed to oscillatory shear stress. TRAIL significantly reduced ROS formation in HAECs exposed to both TNF-α and hyperglycemia. Therefore, TRAIL appears to confer atheroprotective effects on the endothelium, at least in part, by reducing oxidative stress.

Keywords: TRAIL; atherosclerosis; endothelium; oxidative stress.

Figure 1

TRAIL receptor expression by untreated HAECs. Each lane represents the PCR product derived at a specific primer melting temperature. Primer melting temperatures ranged from 55 to 66°C and samples were loaded in duplicate. bp, base; DcR1, decoy receptor 1; DcR2, decoy receptor 2; DR4, death receptor 4; DR5, death receptor 5; HAECs, human aortic endothelial cells; TRAIL, tumor necrosis factor‐related apoptosis‐inducing ligand

Figure 2

TRAILs effect on pro‐inflammatory cytokine‐induced ROS release by HAECs. (a + b) TNF‐ α exposure. (a) Flow cytometry overlay of DHE fluorescence intensity. (b) Histogram of mean DHE fluorescence relative to control for each condition outlined. (c + d) Hyperglycemia exposure. (c) Flow cytometry overlay of DHE fluorescence intensity. (d) Histogram of mean DHE fluorescence relative to control for each condition outlined N = 3, Data are presented as mean ± SEM. *=p < .05 compared to control. σ =p < .05 compared to TRAIL. DHE, dihydroethidium; HAECs, human aortic endothelial cells; HAECs, human aortic endothelial cells; ROS, reactive oxygen species; SEM, standard error of the mean; TNF‐α, tumor necrosis factor alpha; TRAIL, tumor necrosis factor‐related apoptosis‐inducing ligand