REN and hypertensive disorder: Directly implicating CD14+ human macrophages in the development of clinical hypertension is their robust expression of angiotensin-converting enzyme (69, 71), demonstrating their potential involvement in hypertension through participation in the renin-angiotensin-aldosterone system (RAAS), which may lead to feedforward activation of monocytes and “switching” between the M1 and M2 phenotypes (69).