Cyclic-strain-induced endothelial cell expression of adhesion molecules and their roles in monocyte-endothelial interaction

Vascular endothelial cells (ECs) are constantly subjected to hemodynamic forces that may regulate monocyte-endothelial interaction in vivo. To examine the effects of cyclic strain on endothelial expression of monocyte adhesion molecules, E-selectin, intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) ECs were exposed to physiologically relevant levels of cyclic strain. When ECs were under 25% maximal strain at 30 cycles/min for 24 h, the expression of E-selectin significantly (p<0.05) increased, by 83%, compared to control ECs under static conditions. Similarly, monocyte adhesion to ECs under strain (maximum of 15 or 25% at 30 and 60 cycles/min for 24 h) also significantly (p<0.05) increased, by >82%. This cyclic-strain-induced monocyte adhesion was substantially inhibited (83.5%) by anti-E-selectin antibody. ICAM-1 expression also significantly increased, by 62%, when ECs were under 25% maximal strain at 30 cycles/min for 3 h whereas VCAM-1 expression by ECs under strain (for 0.5, 3, and 24 h) did not change compared to static ECs. When ECs were treated with anti-ICAM-1 antibody and monocytes with anti-VLA-4 antibody, an increase in monocyte adhesion to ECs under cyclic strain was reduced significantly. These results demonstrate that cyclic strain can induce EC expression of monocyte adhesion molecules E-selectin, ICAM-1, and VCAM-1 in a time-dependent manner and thus can mediate monocyte adhesion.