Hemodynamic Regulation of Inflammation at the Endothelial-Neutrophil Interface

Arterial shear stress can regulate endothelial phenotype. The potential for anti-inflammatory effects of shear stress on TNFα-activated endothelium was tested in assays of cytokine expression and neutrophil adhesion. In cultured human aortic endothelial cells (HAEC), arterial shear stress of 10 dyne/cm2 blocked by > 80% the induction by 5 ng/ml TNFα of interleukin-8 (IL-8) and IL-6 secretion (50% and 90% reduction, respectively, in the presence of nitric oxide synthase antagonism with 200 μM nitro-L-arginine methylester, L-NAME). Exposure of TNFα-stimulated HAEC to arterial shear stress for 5 hr also reduced by 60% (P &#; 0.001) the conversion of neutrophil rolling to firm arrest in a venous flow assay conducted at 1 dyne/cm2. Also, neutrophil rolling lengths at 1 dyne/cm2 were longer when TNFα-stimulated HAEC were presheared for 5 hr at arterial stresses. In experiments with a synthetic promoter that provides luciferase induction to detect cis interactions of glucocorticoid receptor (GR) and NFκB, shear stress caused a marked 40-fold induction of luciferase in TNFα-treated cells, suggesting a role for GR pathways in the anti-inflammatory actions of fluid shear stress. Hemodynamic force exerts anti-inflammatory effects on cytokine activated endothelium by attenuation of cytokine expression and neutrophil firm arrest.