Novel RAAS agonists and antagonists: clinical applications and controversies

The renin-angiotensin-aldosterone system (RAAS) regulates blood pressure homeostasis and vascular injury and repair responses. The RAAS was originally thought to be an endocrine system critically important in regulating blood pressure homeostasis. Yet, important local forms of the RAAS have been described in many tissues, which are mostly independent of the systemic RAAS. These systems have been associated with diverse physiological functions, but also with inflammation, fibrosis and target-organ damage. Pharmacological modulation of the RAAS has brought about important advances in preventing morbidity and mortality associated with cardiovascular disease. Yet, traditional RAAS blockers such as angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) only reduce the risk of disease progression in patients with established cardiovascular or renal disease by similar to 20% compared with other therapies. As more components of the RAAS are described, other potential therapeutic targets emerge, which could provide improved cardiovascular and renal protection beyond that provided by an ACE inhibitor or ARB. This Review summarizes the present and future pharmacological manipulation of this important system.