Effects of the vasopeptidase inhibitor, omapatrilat, in 723 patients with coronary heart disease

Neprilysin inhibition in chronic kidney disease

Despite current practice, patients with chronic kidney disease (CKD) are at increased risk of progression to end-stage renal disease and cardiovascular events. Neprilysin inhibition (NEPi) is a new therapeutic strategy with potential to improve outcomes for patients with CKD. NEPi enhances the activity of natriuretic peptide systems leading to natriuresis, diuresis and inhibition of the renin–angiotensin system (RAS), which could act as a potentially beneficial counter-regulatory system in states of RAS activation such as chronic heart failure (HF) and CKD. Early NEPi drugs were combined with angiotensin-converting enzyme inhibitors but were associated with unacceptable rates of angioedema and, therefore, withdrawn. However, one such agent (omapatrilat) showed promise of NEP/RAS inhibition in treating CKD in animal models, producing greater reductions in proteinuria, glomerulosclerosis and tubulointerstitial fibrosis compared with isolated RAS inhibition. A new class of drug called angiotensin receptor neprilysin inhibitor (ARNi) has been developed. One such drug, LCZ696, has shown substantial benefits in trials in hypertension and HF. In CKD, HF is common due to a range of mechanisms including hypertension and structural heart disease (including left ventricular hypertrophy), suggesting that ARNi could benefit patients with CKD by both retarding the progression of CKD (hence delaying the need for renal replacement therapy) and reducing the risk of cardiovascular disease. LCZ696 is now being studied in a CKD population.

Roles of proteolysis in regulation of GPCR function

The enzymatic activity of peptidases must be tightly regulated to prevent uncontrolled hydrolysis of peptide bonds, which could have devastating effects on biological systems. Peptidases are often generated as inactive propeptidases, secreted with endogenous inhibitors, or they are compartmentalized. Propeptidases become active after proteolytic removal of N-terminal activation peptides by other peptidases. Some peptidases only become active towards substrates only at certain pHs, thus confining activity to specific compartments or conditions. This review discusses the different roles proteolysis plays in regulating GPCRs. At the cell-surface, certain GPCRs are regulated by the hydrolytic inactivation of bioactive peptides by membrane-anchored peptidases, which prevent signalling. Conversely, cell-surface peptidases can also generate bioactive peptides, which directly activate GPCRs. Alternatively, cell-surface peptidases activated by GPCRs, can generate bioactive peptides to cause transactivation of receptor tyrosine kinases, thereby promoting signalling. Certain peptidases can signal directly to cells, by cleaving GPCR to initiate intracellular signalling cascades. Intracellular peptidases also regulate GPCRs; lysosomal peptidases destroy GPCRs in lysosomes to permanently terminate signalling and mediate down-regulation; endosomal peptidases cleave internalized peptide agonists to regulate GPCR recycling, resensitization and signalling; and soluble intracellular peptidases also participate in GPCR function by regulating the ubiquitination state of GPCRs, thereby altering GPCR signalling and fate. Although the use of peptidase inhibitors has already brought success in the treatment of diseases such as hypertension, the discovery of new regulatory mechanisms involving proteolysis that control GPCRs may provide additional targets to modulate dysregulated GPCR signalling in disease.

Natriuretic peptides: Diagnostic and therapeutic use

Natriuretic peptides (NPs) are hormones which are mainly secreted from heart and have important natriuretic and kaliuretic properties. There are four different groups NPs identified till date [atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP), C-type natriuretic peptide (CNP) and dendroaspis natriuretic peptide, a D-type natriuretic peptide (DNP)], each with its own characteristic functions. The N-terminal part of the prohormone of BNP, NT-proBNP, is secreted alongside BNP and has been documented to have important diagnostic value in heart failure. NPs or their fragments have been subjected to scientific observation for their diagnostic value and this has yielded important epidemiological data for interpretation. However, little progress has been made in harnessing the therapeutic potential of these cardiac hormones.

Perindopril-based blood pressure-lowering therapy reduces amino-terminal-pro-B-type natriuretic peptide in individuals with cerebrovascular disease

OBJECTIVE

The plasma amino-terminal-pro-B-type natriuretic peptide (NT-proBNP) level predicted congestive heart failure, myocardial infarction, and ischaemic stroke in participants of the Perindopril Protection Against Recurrent Stroke Study (PROGRESS), a placebo-controlled study of the effects of blood pressure lowering on cardiovascular events among individuals with cerebrovascular disease. Active treatment comprised a flexible regimen based on perindopril, with the addition of indapamide at the discretion of treating physicians. Active treatment reduced cardiovascular events, and we therefore investigated whether active treatment modified NT-proBNP and other cardiovascular risk factors.

METHODS

We measured NT-proBNP and other cardiovascular risk factors at randomization and after 13 months of therapy in a subset of 357 PROGRESS participants.

RESULTS

Baseline systolic and pulse pressures were higher in individuals with elevated baseline NT-proBNP levels. In comparison with placebo, active treatment reduced the blood pressure and NT-proBNP levels, and increased renin levels. Reduction of NT-proBNP levels by active treatment was most evident in individuals with baseline NT-proBNP levels in the highest quarter (> 26 pmol/l), with a median reduction of 16 pmol/l (interquartile range 0-51 pmol/l, P = 0.004), corresponding to a median decrease of 39% (interquartile range 0-69%). Active treatment reduced blood pressure similarly for individuals in each of the four quarters of baseline NT-proBNP. Active therapy had no effect on plasma lipid, C-reactive protein, homocysteine, or soluble vascular cell adhesion molecule 1 levels.

CONCLUSION

We conclude that plasma NT-proBNP level, in addition to predicting cardiovascular risk, may provide a measure of risk reduction by blood pressure-lowering therapy.