Angiotensin II stimulates intercellular adhesion molecule-1 (ICAM-1) expression by human vascular endothelial cells and increases soluble ICAM-1 release in vivo

Abstract

Background - We evaluated whether angiotensin II (Ang II) influenced intercellular adhesion molecule (ICAM)-1 expression by human vascular endothelial cells derived from umbilical cord veins (HUVECs) and plasma soluble ICAM-1 levels in vivo. Methods and Results - Cultured HUVECs were incubated with Ang II (from 10-9 to 10-6 mol/L) with or without candesartan and PD12319 (inhibitors of Ang II AT1 and AT2 receptors, respectively) for various times up to 4 hours. Total RNA was then extracted from HUVECs, and Northern blots were probed with a 1.9-kb ICAM-1 cDNA fragment. HUVEC supernatants were used to assess soluble ICAM-1 release by ELISA. Northern blot analysis detected a strong increase of ICAM-1 mRNA after 2-hour incubation with Ang II. The response was inhibited by candesartan. Soluble ICAM-1 release by HUVECs also increased (P<0.002) after 2-hour Ang II stimulation. In vivo, Ang II (at an initial rate of 1.0 ng · kg-1 · min-1, to be increased each 30 minutes by 2.0 ng · kg-1 · min-1 to the final rate of 7.0 ng · kg-1 · min-1) was infused in 8 normotensive and 12 essential hypertensive individuals. In the latter, Ang II was reinfused after 4 weeks on either placebo (n=3), losartan (50 mg UID, n=5), or atenolol (50 mg UID, n=4) treatment. Plasma soluble ICAM-1 levels increased after Ang II infusion in hypertensives and normotensives (P<0.0001 after 90 minutes). Losartan reduced baseline soluble ICAM-1 levels (P<0.05) and Ang II-related ICAM-1 increments. Conclusions - Ang II upregulates ICAM-1 expression by HUVECs and stimulates in vitro and in vivo soluble ICAM-1 release. AT1 receptor blockade inhibits such endothelial effects of Ang II.