Regulation of vascular and renal cells by common mediators in health and disease: Role of the renin-angiotensin system in the pathophysiology of hypertension and cardiovascular disease

Abstract

In the classic view of the renin angiotensin system (RAS), angiotensin II (AngII) is the main effector peptide. Circulating RAS regulates physiological responses, whereas the local RAS is activated during tissue injury and contributes to pathological processes, including cell proliferation/apoptosis, fibrosis, and inflammation. AngII has direct effects on these processes through activation of mitogen-activated protein kinase (MAPKs) and Smad and nuclear factor kappa B (NF-κB) transcription factors. In addition, AngII recruits important secondary mediators, such as transforming growth factor beta (TGF-β), connective tissue growth factor (CTGF), and chemokines. AngII binds to the angiotensin type 1 and 2 (AT1 and AT2) receptors mediating different cellular responses. Both angiotensin-converting enzyme (ACE) inhibitors and AngII receptor antagonists (ARA II, targeting the AT1 receptor) have demonstrated their therapeutic efficacy in protecting the cardiovascular system and kidneys in humans. Some AngII degradation peptides are also biologically active. Aminopeptidases promote the generation of AngIII and AngIV, two N-terminal degradation products, whereas ACE-2 catalyzes generation of Ang-(1-7). AngIV has been reported to bind to the AngIV-binding-site insulinregulated aminopeptidase (IRAP) and to promote inflammation in vascular cells. Ang-(1-7) activation of the Mas receptor may be beneficial in vascular injury but increases kidney inflammation. © 2010 Springer-Verlag Milan.