28 September 2005
Angiotensin-converting enzyme (ACE) inhibitors interfere with several key events of vascular inflammation resulting in impressive reductions in coronary vascular events. However, in human arteries ACE inhibitors block the production of angiotensin II (AngII) incompletely because of the involvement of alternative pathways in local AngII formation. Therefore, our study concentrated on the presumed modulation by ACE inhibition of local AngII-mediated inflammatory actions by a mechanism independent of blockage of AngII formation. We analyzed the effect of the ACE inhibitor ramiprilat on AngII-dependent cell adhesion molecule (CAM) expression and adhesion of monocytic THP-1 cells to endothelial cells. AngII induced upregulation of P-selectin, VCAM-1 and ICAM-1 on endothelial cells via activation of AT1, which was correlated with enhanced THP-1 adhesion in flow chamber assays. Both enhanced adhesion and adhesion molecule expression were significantly reduced by pretreatment with ramiprilat. Ramiprilat reduced AT1 expression on endothelial cells and decreased the AngII-induced p65 translocation into the nucleus. Diminished AT1 expression and adhesion molecule expression in response to ramiprilat treatment were partially reversed after incubation with a bradykinin 2 receptor antagonist, suggesting that elevated bradykinin levels under ACE inhibition may be involved in the beneficial effect of ACE inhibitors. Thus, modulation of the local AngII system by ramiprilat may at least in part contribute to the benefits of ACE inhibition in the treatment of atherosclerotic diseases.