Combination of shear stress and hydrostatic pressure decreases ICAM-1, VCAM- 1 and E-selectin expressions induced by TNF-α in cultured endothelial cells

Abstract

Endothelial cells are constantly subjected to shear stress, a tangential stress generated by blood flow, and hydrostatic pressure, a normal stress generated by blood pressure. Using our perfusion system that enables the independent control of flow volume and pressure, we investigated the effect of combined stress on adhesion molecule expressions in cultured endothelial cells stimulated by cytokine. Human umbilical vein endothelial cells (HUVECs) were incubated with 25 ng/ml tumor necrosis factor-alpha (TNF-α) for 6 hours. Then, activated endothelial cells were exposed to pulsatile flow (a shear stress of 1.2/1.8 Pa and a hydrostatic pressure of 80/120 mmHg) for 1-24 hours. After exposure to pulsatile flow intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and endothelial selectin (E-selectin) were stained and were observed using a fluorescence microscopy. Results showed that ICAM-1 was almost expressed in HUVECs after stimulation of TNF-α, however, TNF-α-induced ICAM-1 expression was decreased from 12 hours after exposure to pulsatile flow. As a result ICAM-1 was expressed in approximately 40% of the total HUVECs at 24 hours. VCAM- 1 was expressed in approximately 75% of the total HUVECs after stimulation of TNF-α, however, TNF-α-induced VCAM-1 expression was decreased from 6 hours after exposure to pulsatile flow. As a result VCAM-1 was expressed in approximately 40% of the total HUVECs at 24 hours. E-selectin was expressed in approximately 30% of the total HUVECs after stimulation of TNF-α, however, TNF-α-induced E-selectin expression was decreased from 1 hour after exposure to pulsatile flow. As a result E-selectin was expressed under 10% of the total HUVECs at 24 hours. These results suggest that combined stress plays significant roles in selectively suppressing TNF-α-induced expressions of adhesion molecules in endothelial cells. © 2011 Springer-Verlag Berlin Heidelberg.