Novel Antiinflammatory Vascular Benefits of Systemic and Stent-Based Delivery of Ethylisopropylamiloride

Abstract

Background— Recently, we demonstrated that the amiloride derivative ethylisopropylamiloride (EIPA) limits vascular smooth muscle cell growth and migration. The purpose of the present experiments was to determine whether EIPA can also reduce the inflammatory component of atherogenesis and stent neointima formation. Methods and Results— To determine the effect of EIPA on the early inflammatory stages of atherogenesis, apolipoprotein E null mice (apoE −/− ) fed an atherogenic diet received a subcutaneous pump infusion of either EIPA (3 mg · kg −1 d −1 ) or the control vehicle for 4 weeks. The en face aortic area of atherosclerotic lesions and the subendothelial accumulation of macrophages were reduced by 46% and 38%, respectively, in EIPA-treated mice. Moreover, the number of vascular cell adhesion molecule-1 (VCAM-1) immunopositive lumenal endothelial cells was 59% less in the EIPA treatment group. In vitro, there was a concentration-dependent inhibition of lipopolysaccharide (LPS)-induced VCAM-1 expression with a corresponding 37% reduction in U-937 cell adhesion to endothelial cells. EIPA also reduced LPS-stimulated nuclear factor-κB (NF-κB) activation as reflected by a 66% reduction in NF-κB nuclear translocation. Finally, to test the effect of EIPA on the early inflammatory reaction to stent implantation, stents coated with jelly alone or jelly plus EIPA were implanted into rabbit iliac arteries. Four weeks later, the stent neointimal area, abundance of peristrut macrophages, and density of intimal smooth muscle cells were reduced by 38%, 47%, and 37%, respectively, for EIPA stents. Conclusions— EIPA downregulates endothelial cell activation of NF-κB and VCAM-1 expression and attenuates the early inflammatory stages of atherogenesis and stent intimal formation.