Evolving Role of Natriuretic Peptides from Diagnostic Tool to Therapeutic Modality

Effects of cGMP/Akt/GSK-3β signaling pathway on atrial natriuretic peptide secretion in rabbits with rapid atrial pacing

Atrial natriuretic peptide (ANP) plays a pivotal role in the regulation of the cardiovascular system. The ANP level increases during atrial fibrillation (AF), suggesting that AF may provoke ANP secretion, but its potential mechanism is still unclear. In the present study, the potential mechanisms of rapid atrial pacing (RAP) regulating ANP secretion was explored. Rabbits were subjected to burst RAP, ANP secretion increased whereas cyclic guanosine monophosphate (cGMP) concentrations decreased during RAP. The p-Akt and p-GSK-3β levels decreased in atrial tissues. Natriuretic peptide receptor A (NPR-A) protein and particulate guanylate cyclase (PGC) activity were detected. The sensitivity of NPR-A to ANP decreased, leading to the decrease of PGC activity. Also, the isolated atrial perfusion system were made in the rabbit model, cGMP was shown to inhibit ANP secretion, and the Akt inhibitor LY294002 (LY) and GSK-3β inhibitor SB216763 (SB) attenuated the inhibitory effects of cGMP on ANP secretion and enhanced the inhibitory effects of cGMP on atrial dynamics. In conclusion, NPR-A interacts with ANP to regulate PGC expression, and influence the expression of cGMP during RAP, which involves in the Akt/GSK-3β signaling pathway. From the aforementioned points we conclude that cGMP regulates ANP secretion by the Akt/GSK-3β signaling pathway during atrial pacing.

Development of Peptide Biopharmaceuticals in Russia

Peptides are low-molecular-weight substances that participate in numerous important physiological functions, such as human growth and development, stress, regulation of the emotional state, sexual behavior, and immune responses. Their mechanisms of action are based on receptor–ligand interactions, which result in highly selective effects. These properties and low toxicity enable them to be considered potent drugs. Peptide preparations became possible at the beginning of the 20th century after a method was developed for selectively synthesizing peptides; however, after synthesis of the first peptide drugs, several issues related to increasing the stability, bioavailability, half-life, and ability to move across cell membranes remain unresolved. Here, we briefly review the history of peptide production and development in the biochemical industry and outline potential areas of peptide biopharmaceutical applications and modern approaches for creating pharmaceuticals based on synthetic peptides and their analogs. We also focus on original peptide drugs and the approaches used for their development by the Russian Federation.

Higher plasma NT-proBNP levels correlate with syndrome of inappropriate antidiuretic hormone and poor prognosis in neurological patients

Background

Hyponatremia induced by syndrome of inappropriate antidiuretic hormone secretion (SIADH) was common electrolyte disturbance encountered in critically ill neurological diseases, which has normal or increased fluid volume. Brain natriuretic peptide (BNP), which is released in equal proportion to N-terminal pro-brain natriuretic peptide (NT-proBNP), plays vital roles in regulation of volume status. The relationship between SIADH and NT-proBNP levels in neurological diseases has rarely been reported.

Methods

A retrospective cross-sectional study was conducted to analyze plasma NT-proBNP levels in 33 patients with SIADH and 23 controlled eunatremic patients with neurological diseases.

Results

Baseline NT-proBNP levels were compared between two groups [SIADH group: median 311 pg/mL, interquartile range (IQR) 110–768 pg/mL] vs. eunatremic group: median 46 pg/mL, IQR, 12–96 pg/mL) (P<0.05). Plasma NT-proBNP levels were markedly increased in hyponatremic patients who had two or more complications than those who had less complication (P<0.05). In SIADH patients, NT-proBNP levels in remission phase were lower to levels at baseline. Furthermore, no death was seen in eunatremic patients, while five SIADH patients died from complications.

Conclusions

SIADH had higher plasma NT-proBNP levels and poorer prognosis compared to eunatremic neurological patients. NT-proBNP serves as a biomarker of disease severity while not extracellular volume (ECV) status in critically ill neurological patients.

Neprilysin: A Potential Therapeutic Target of Arterial Hypertension?

Arterial hypertension is the most prevalent chronic disease in the adult population of developed countries and it constitutes a significant risk factor in the development of cardiovascular disease, contributing to the emergence of many comorbidities, among which heart failure excels, a clinical syndrome that nowadays represents a major health problem with uncountable hospitalizations and the indolent course of which progressively worsens until quality of life decreases and lastly death occurs prematurely. In the light of this growing menace, each day more efforts are invested in the field of cardiovascular pharmacology, searching for new therapeutic options that allow us to modulate the physiological systems that appear among these pathologies. Therefore, in the later years, the study of natriuretic peptides has become so relevant, which mediate beneficial effects at the cardiovascular level such as diuresis, natriuresis, and decreasing cardiac remodeling; their metabolism is mediated by neprilysin, a metalloproteinase, widely expressed in the human and capable of catalyzing many substrates. The modulation of these functions has been studied by decades, giving room to Sacubitril, the first neprilysin inhibitor, which in conjunction with an angiotensin receptor blocker has provided a high efficacy and tolerability among patients with heart failure, for whom it has already been approved and recommended. Nonetheless, in the matter of arterial hypertension, significant findings have arisen that demonstrate the potential role that it will play among the pharmacological alternatives in the upcoming years.

Serum and Echocardiographic Markers May Synergistically Predict Adverse Cardiac Remodeling after ST-Segment Elevation Myocardial Infarction in Patients with Preserved Ejection Fraction

Improvement of risk scoring is particularly important for patients with preserved left ventricular ejection fraction (LVEF) who generally lack efficient monitoring of progressing heart failure. Here, we evaluated whether the combination of serum biomarkers and echocardiographic parameters may be useful to predict the remodeling-related outcomes in patients with ST-segment elevation myocardial infarction (STEMI) and preserved LVEF (HFpEF) as compared to those with reduced LVEF (HFrEF). Echocardiographic assessment and measurement of the serum levels of NT-proBNP, sST2, galectin-3, matrix metalloproteinases, and their inhibitors (MMP-1, MMP-2, MMP-3, TIMP-1) was performed at the time of admission (1st day) and on the 10th–12th day upon STEMI onset. We found a reduction in NT-proBNP, sST2, galectin-3, and TIMP-1 in both patient categories from hospital admission to the discharge, as well as numerous correlations between the indicated biomarkers and echocardiographic parameters, testifying to the ongoing ventricular remodeling. In patients with HFpEF, NT-proBNP, sST2, galectin-3, and MMP-3 correlated with the parameters reflecting the diastolic dysfunction, while in patients with HFrEF, these markers were mainly associated with LVEF and left ventricular end-systolic volume/diameter. Therefore, the combination of the mentioned serum biomarkers and echocardiographic parameters might be useful for the prediction of adverse cardiac remodeling in patients with HFpEF.

Respiratory chain signalling is essential for adaptive remodelling following cardiac ischaemia

Cardiac ischaemia-reperfusion (I/R) injury has been attributed to stress signals arising from an impaired mitochondrial electron transport chain (ETC), which include redox imbalance, metabolic stalling and excessive production of reactive oxygen species (ROS). The alternative oxidase (AOX) is a respiratory enzyme, absent in mammals, that accepts electrons from a reduced quinone pool to reduce oxygen to water, thereby restoring electron flux when impaired and, in the process, blunting ROS production. Hence, AOX represents a natural rescue mechanism from respiratory stress. This study aimed to determine how respiratory restoration through xenotopically expressed AOX affects the re-perfused post-ischaemic mouse heart. As expected, AOX supports ETC function and attenuates the ROS load in post-anoxic heart mitochondria. However, post-ischaemic cardiac remodelling over 3 and 9 weeks was not improved. AOX blunted transcript levels of factors known to be up-regulated upon I/R such as the atrial natriuretic peptide (Anp) whilst expression of pro-fibrotic and pro-apoptotic transcripts were increased. Ex vivo analysis revealed contractile failure at nine but not 3 weeks after ischaemia whilst label-free quantitative proteomics identified an increase in proteins promoting adverse extracellular matrix remodelling. Together, this indicates an essential role for ETC-derived signals during cardiac adaptive remodelling and identified ROS as a possible effector.

Limited value of NT-proBNP as a prognostic marker of all-cause mortality in patients with heart failure with preserved and mid-range ejection fraction in primary care: A report from the swedish heart failure register

Aim: The prognostic value of natriuretic peptides in the management of heart failure (HF) patients with ejection fraction (EF) <40% is well established, but is less known for those with EF ≥40% managed in primary care (PC). Therefore, the aim of this study is to describe the prognostic significance of plasma NT-proBNP in such patients managed in PC.Subjects: We included 924 HF patients (48% women) with EF ≥40% and NT-proBNP registered in the Swedish Heart Failure Registry. Follow-up was 1100 ± 687 days.Results: One-, three- and five-year mortality rates were 8.1%, 23.9% and 44.7% in patients with EF 40-50% (HFmrEF) and 7.3%, 23.6% and 37.2% in patients with EF ≥50% (HFpEF) (p = 0.26). Patients with the highest mean values of NT-proBNP had the highest all-cause mortality but wide standard deviations (SDs). In univariate regression analysis, there was an association only between NT-proBNP quartiles and all-cause mortality. In HFmrEF patients, hazard ratio (HR) was 1.96 (95% CI 1.60-2.39) p < 0.0001) and in HFpEF patients, HR was 1.72 (95% CI 1.49-1.98) p < 0.0001). In a multivariate Cox proportional hazard regression analysis, adjusted for age, NYHA class, atrial fibrillation and GFR class, this association remained regarding NT-proBNP quartiles [HR 1.83 (95% CI 1.38-2.44), p < 0.0001] and [HR 1.48 (95% CI 1.16-1.90), p = 0.0001], HFmrEF and HFpEF, respectively.Conclusion: NT-proBNP has a prognostic value in patients with HF and EF ≥40% managed in PC. However, its clinical utility is limited due to high SDs and the fact that it is not independent in this population which is characterized by high age and much comorbidity.Key pointsIt is uncertain whether NT-proBNP predicts risk in heart failure with preserved ejection fraction (EF > 40%, HFpEF) managed in primary care.We show that high NT-proBNP predicts increased all-cause mortality in HFpEF-patients managed in primary care.The clinical use is however limited due to large standard deviations, many co-morbidities and high age.Many of these co-morbidities contribute to all-cause mortality and management of these patients should also focus on these co-morbidities.

ASB20123: A novel C-type natriuretic peptide derivative for treatment of growth failure and dwarfism

C-type natriuretic peptide (CNP) and its receptor natriuretic peptide receptor B (NPR-B) are physiological potent positive regulators of endochondral bone growth; therefore, the CNP/NPR-B signaling pathway is one of the most promising therapeutic targets for treating growth failure and dwarfism. In this article, we summarized the pharmacological properties of a novel CNP analog peptide ASB20123 as a therapeutic agent for short stature. ASB20123, one of the CNP/ghrelin chimeric peptides, is composed of CNP(1-22) and human ghrelin(12-28, E17D). Compared to CNP(1-22), ASB20123 showed similar agonist activity for NPR-B and improved biokinetics with a longer plasma half-life in rats. In addition, the distribution of ASB20123 to the cartilage was higher than that of CNP(1-22) after single subcutaneous (sc) injection to mice. These results suggested that the C-terminal part of ghrelin, which has clusters of basic amino acid residues and a BX7B motif, might contribute to the retention of ASB20123 in the extracellular matrix of the growth plate. Multiple sc doses of ASB20123 potently stimulated skeletal growth in rats in a dose-dependent manner, and sc infusion was more effective than bolus injection at the same dose. Our data indicated that high plasma levels of ASB20123 would not necessarily be required for bone growth acceleration. Thus, pharmaceutical formulation approaches for sustained-release dosage forms to allow chronic exposure to ASB20123 might be suitable to ensure drug effectiveness and safety.