Figure 1.
The renin angiotensin system. The RAS is composed of multiple substrates and enzymes that can act in concert or separately to exert physiologic actions. The most well described function of the RAS is regulation of BP homeostasis. Angiotensinogen is converted to Ang I by renin in the circulation. Ang I is subsequently cleaved by ACE to produce Ang II, an effector molecule that increases vascular tone and promotes sodium reabsorption in the kidney by ligating the AT1 receptor. Apart from these canonic functions, several components of the RAS modulate immune responses. (Pro)renin and ACE regulate hematopoietic cell differentiation. AT1 receptor activation in immune cells versus the kidney exerts divergent effects on tissue inflammation. By degrading Ang II and/or by catalyzing the generation of Ang 1–7, ACE2 ameliorates inflammatory injury in the kidney and vasculature.