oa Prevention of Atherosclerosis by Interference with the Vascular Nitric Oxide System

Nitric oxide (NO) produced by endothelial NO synthase (eNOS) represents an anti-atherosclerotic principle. NO bioavailability is decreased in atherosclerosis due to increased NO inactivation by reactive oxygen species and reduced NO synthesis. Various types of vascular pathophysiology are associated with oxidative stress, with NADPH oxidases as the major source of reactive oxygen species. These inactivate NO. Also, oxidative stress is likely to be the main cause for oxidation of the essential NOS cofactor, tetrahydrobiopterin (BH4). A lack of BH4 leads to eNOS uncoupling (i.e., uncoupling of oxygen reduction from NO synthesis in eNOS). Based on these pathomechanisms, the therapeutic potential of a number of compounds is discussed in this review: (1) NO donors; (2) L-arginine; (3) folic acid; (4) BH4 and its precursor sepiapterin; (5) compounds that upregulate eNOS and concomitantly maintain eNOS activity (e.g. midostaurin, betulinic acid, ursolic acid, AVE9488 and AVE3085); (6) compounds that enhance the de novo synthesis of BH4 by stimulating expression or activity of GTP cyclohydrolase I; and (7) 3-hydroxy-3-methylglutarylcoenzyme A inhibitors (statins) and drugs interrupting the renin-angiotensin-aldosterone system. Statins, angiotensin II type 1 receptor blockers, angiotensin-converting enzyme (ACE) inhibitors, the aldosterone antagonist eplerenone and the renin inhibitor aliskiren enhance NO bioactivity and reduce atherosclerosis progression through multiple mechanisms.