Angiotensin-Converting Enzyme 2 Activation Is Not a Common Feature of Angiotensin-Converting Enzyme Inhibitory Peptides

Angiotensin-converting enzyme (ACE) catalyzes the formation of angiotensin II (Ang II), a vasoconstrictor, whereas its homologue ACE2 degrades Ang II into angiotensin (1-7) (Ang (1-7)), a vasodilator. Given the similarities in structure and their interconnected roles in the regulation of cardiovascular system, this study aims to investigate if ACE-inhibitory (ACEi) peptides can also activate ACE2. About 200 potent ACEi peptides were subjected to molecular docking, 20 peptides were selected for cell and in vitro enzymatic activity studies, and 5 peptides were fed orally to spontaneously hypertensive rats at a dose of 15 mg/kg body weight/day for 7 days. Peptides IKW and RIY showed significant antihypertensive activity with activated circulating/aortic ACE2, circulating Ang (1-7), and decreased Ang II levels. IQY reduced blood pressure, increased Ang (1-7) level, but did not affect ACE and ACE2. Peptides MAW and MRW did not affect blood pressure, ACE, and ACE2. Our study showed that ACE2 activation is not a common feature of ACEi peptides.

Potential of Renin-Angiotensin-Aldosterone System Modulations in Diabetic Kidney Disease: Old Players to New Hope!

Due to a tragic increase in the incidences of diabetes globally, diabetic kidney disease (DKD) has emerged as one of the leading causes of end-stage renal diseases (ESRD). Hyperglycaemia-mediated overactivation of the renin-angiotensin-aldosterone system (RAAS) is key to the development and progression of DKD. Consequently, RAAS inhibition by angiotensin-converting enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARBs) is the first-line therapy for the clinical management of DKD. However, numerous clinical and preclinical evidences suggested that RAAS inhibition can only halt the progression of the DKD to a certain extent, and they are inadequate to cure DKD completely. Recent studies have improved understanding of the complexity of the RAAS. It consists of two counter-regulatory arms, the deleterious pressor arm (ACE/angiotensin II/AT1 receptor axis) and the beneficial depressor arm (ACE2/angiotensin-(1-7)/Mas receptor axis). These advances have paved the way for the development of new therapies targeting the RAAS for better treatment of DKD. In this review, we aimed to summarise the involvement of the depressor arm of the RAAS in DKD. Moreover, in modern drug discovery and development, an advance approach is the bispecific therapeutics, targeting two independent signalling pathways. Here, we discuss available reports of these bispecific drugs involving the RAAS as well as propose potential treatments based on neurohormonal balance as credible therapeutic strategies for DKD.