Shear stress preconditioning modulates endothelial susceptibility to circulating TNF-α and monocytic cell recruitment in a simplified model of arterial bifurcations

Abstract

Objective Atherosclerotic plaque formation results from a combination of local shear stress patterns and inflammatory processes. This study investigated the endothelial response to shear stress in combination with the inflammatory cytokine TNF-α in a simplified model of arterial bifurcation. Methods Human umbilical vein endothelial cells (ECs) were exposed to laminar or non-uniform shear stress in bifurcating flow-through slides, followed by stimulation with TNF-α. To study cell adhesion, ECs were perfused with medium containing THP-1 monocytic cells. Endothelial protein expression was determined by immunofluorescence. Results Adhesion of monocytic cells to unstimulated ECs was nearly undetectable under laminar shear stress and was slightly increased under non-uniform shear stress. Exposure of ECs to non-uniform shear stress in combination with TNF-α induced a 12-fold increase in monocytic cell recruitment and a significant induction of endothelial E-selectin and VCAM-1 expression. Both these effects were prevented in ECs exposed to laminar shear stress. The significant differences in TNF-α-induced monocytic cell recruitment and adhesion molecule expression between laminar and non-uniform shear stress regions were abolished in the absence of shear stress preconditioning. Simvastatin (1 μmol/L) suppressed the non-uniform shear stress- and TNF-α-induced increase in monocytic cell adhesion by about 30% via inhibition of VCAM-1 expression. Resveratrol, the active component of red wine, inhibited the expression of both VCAM-1 and E-selectin, and reduced monocytic cell recruitment by 50% at 20 μmol/L. Conclusions Non-uniform shear stress induces endothelial susceptibility to circulating TNF-α and adhesion of monocytic cells. Interference with this process may inhibit inflammatory response in atherosclerosis-prone regions.