Angiotensin II induces vascular cell adhesion molecule-1 expression in rat vasculature: A potential link between the renin-angiotensin system and atherosclerosis

Abstract

Background: Cardiovascular ischemic events may occur more frequently in hypertensive patients with activated renin-angiotensin systems. We tested the hypothesis that angiotensin II (Ang II) may contribute to atherosclerosis by increasing expression of vascular inflammatory genes such as vascular cell adhesion molecule-1 (VCAM-1).

Methods and results: Rats infused with norepinephrine or Ang II for 6 days developed similar hypertensive responses, but only Ang II-treated rats exhibited significant increases in aortic VCAM-1 protein and mRNA expression. Oral losartan treatment (50 mg. kg(-1). d(-1)) inhibited Ang II-induced hypertension and aortic VCAM-1 mRNA expression. Ang II treatment significantly increased VCAM-1 mRNA expression in cultured rat aortic smooth muscle cells (RASMCs). Ang II also induced nuclear NF-kappaB-like binding activity and transactivated an NF-kappaB-driven VCAM-1 promoter. Losartan and proteasome inhibitors blocked Ang II-induced NF-kappaB activation and VCAM-1 mRNA accumulation. IkappaB-alpha overexpression in RASMCs inhibited Ang II-induced VCAM-1 promoter transactivation.

Conclusions: Ang II may contribute to atherogenesis by activation of VCAM-1 through proteasome dependent, NF-kappaB-like transcriptional mechanisms.