Natriuretic peptides and therapeutic applications

Novel Biomarkers in Early Detection of Heart Failure: A Narrative Review

Heart failure (HF) represents a significant global health challenge, characterized by a variety of symptoms resulting from cardiac dysfunction. This dysfunction often leads to systemic and pulmonary congestion. The pathophysiology of HF is complex, involving stimulation of the sympathetic nervous system, which is insufficiently balanced by the release of natriuretic peptide. This imbalance leads to progressive hypertrophy and dilatation of the heart's chambers, impairing its pumping efficiency and increasing the risk of arrhythmias and conduction disorders. The prevalence of HF is exceptionally high in industrialized nations and is expected to increase owing to an aging population and advancements in diagnostic methods. This study emphasizes the critical role of early diagnosis in reducing morbidity and mortality associated with HF, focusing specifically on the evolving importance of biomarkers in managing this condition. Biomarkers have played a key role in transforming the diagnosis and treatment of HF. Traditional biomarkers such as b-type natriuretic peptide and N-terminal pro-b-type natriuretic peptide have been widely adopted for their cost-effectiveness and ease of access. However, the rise of novel biomarkers such as growth differentiation factor 15 and adrenomedullin has shown promising results, offering superior sensitivity and specificity. These new biomarkers enhance diagnostic accuracy, risk stratification, and prognostic evaluation in HF patients. Despite these advancements, challenges remain, such as limited availability, high costs, and the need for further validation in diverse patient populations. Through a comprehensive literature review across databases such as PubMed, Google Scholar, and the Cochrane Library, this study compiles and analyzes data from 18 relevant studies, offering a detailed understanding of the current state of HF biomarkers. The study examines both traditional and emerging biomarkers such as galectin-3 and soluble suppression of tumorigenicity 2 in HF, exploring their clinical roles and impact on patient outcomes.

Evidence for Angiotensin II as a Naturally Existing Suppressor for the Guanylyl Cyclase A Receptor and Cyclic GMP Generation

The natriuretic peptide system (NPS) and renin-angiotensin-aldosterone system (RAAS) function oppositely at multiple levels. While it has long been suspected that angiotensin II (ANGII) may directly suppress NPS activity, no clear evidence to date supports this notion. This study was designed to systematically investigate ANGII-NPS interaction in humans, in vivo, and in vitro. Circulating atrial, b-type, and c-type natriuretic peptides (ANP, BNP, CNP), cyclic guanosine monophosphate (cGMP), and ANGII were simultaneously investigated in 128 human subjects. Prompted hypothesis was validated in vivo to determine the influence of ANGII on ANP actions. The underlying mechanisms were further explored via in vitro approaches. In humans, ANGII demonstrated an inverse relationship with ANP, BNP, and cGMP. In regression models predicting cGMP, adding ANGII levels and the interaction term between ANGII and natriuretic peptides increased the predictive accuracy of the base models constructed with either ANP or BNP, but not CNP. Importantly, stratified correlation analysis further revealed a positive association between cGMP and ANP or BNP only in subjects with low, but not high, ANGII levels. In rats, co-infusion of ANGII even at a physiological dose attenuated cGMP generation mediated by ANP infusion. In vitro, we found the suppressive effect of ANGII on ANP-stimulated cGMP requires the presence of ANGII type-1 (AT1) receptor and mechanistically involves protein kinase C (PKC), as this suppression can be substantially rescued by either valsartan (AT1 blocker) or Go6983 (PKC inhibitor). Using surface plasmon resonance (SPR), we showed ANGII has low binding affinity to the guanylyl cyclase A (GC-A) receptor compared to ANP or BNP. Our study reveals ANGII is a natural suppressor for the cGMP-generating action of GC-A via AT1/PKC dependent manner and highlights the importance of dual-targeting RAAS and NPS in maximizing beneficial properties of natriuretic peptides in cardiovascular protection.

The orchestra of human bacteriome by hormones

Human microbiome interact reciprocally with the host. Recent findings showed the capability of microorganisms to response towards host signaling molecules, such as hormones. Studies confirmed the complex response of bacteria in response to hormones exposure. These hormones impact many aspects on bacteria, such as the growth, metabolism, and virulence. The effects of each hormone seem to be species-specific. The most studied hormones are cathecolamines also known as stress hormones that consists of epinephrine, norepinephrine and dopamine. These hormones affect the growth of bacteria either inhibit or enhance by acting like a siderophore. Epinephrine and norepinephrine have also been reported to activate QseBC, a quorum sensing in Gram-negative bacteria and eventually enhances the virulence of pathogens. Other hormones were also reported to play a role in shaping human microbiome composition and affect their behavior. Considering the complex response of bacteria on hormones, it highlights the necessity to take the impact of hormones on bacteria into account in studying human health in relation to human microbiome.

Endocrine functions of the heart: from bench to bedside

Heart has a recognized endocrine function as it produces several biologically active substances with hormonal properties. Among these hormones, the natriuretic peptide (NP) system has been extensively characterized and represents a prominent expression of the endocrine function of the heart. Over the years, knowledge about the mechanisms governing their synthesis, secretion, processing, and receptors interaction of NPs has been intensively investigated. Their main physiological endocrine and paracrine effects on cardiovascular and renal systems are mostly mediated through guanylate cyclase-A coupled receptors. The potential role of NPs in the pathophysiology of heart failure and particularly their counterbalancing action opposing the overactivation of renin-angiotensin-aldosterone and sympathetic nervous systems has been described. In addition, NPs are used today as key biomarkers in cardiovascular diseases with both diagnostic and prognostic significance. On these premises, multiple therapeutic strategies based on the biological properties of NPs have been attempted to develop new cardiovascular therapies. Apart from the introduction of the class of angiotensin receptor/neprilysin inhibitors in the current management of heart failure, novel promising molecules, including M-atrial natriuretic peptide (a novel atrial NP-based compound), have been tested for the treatment of human hypertension. The development of new drugs is currently underway, and we are probably only at the dawn of novel NPs-based therapeutic strategies. The present article also provides an updated overview of the regulation of NPs synthesis and secretion by microRNAs and epigenetics as well as interactions of cardiac hormones with other endocrine systems.

EVIDENCE FOR ANGIOTENSIN II AS A NATURALLY EXISTING SUPPRESSOR FOR THE NATRIURETIC PEPTIDE SYSTEM

Background

Natriuretic peptide system (NPS) and renin angiotensin aldosterone system (RAAS) function oppositely at multiple levels. While it has long been suspected that angiotensin II (ANGII) may directly suppress NPS activity, no clear evidence to date support this notion.

Objectives

This study was designed to systematically investigate ANGII-NPS interaction in humans, in vivo, and in vitro for translational insights.

Methods

Circulating atrial, b-type, and c-type natriuretic peptides (ANP, BNP, CNP), cyclic guanosine monophosphate (cGMP), and ANGII were simultaneously investigated in 128 human subjects. Prompted hypothesis was validated in rat model to determine influence of ANGII on ANP actions. Multiple engineered HEK293 cells and surface plasmon resonance (SPR) technology were leveraged for mechanistic exploration.

Results

In humans, ANGII showed inverse relationship with ANP, BNP, and cGMP. In regression models predicting cGMP, adding ANGII levels and interaction term between ANGII and natriuretic peptide increased predicting accuracy of base models constructed with either ANP or BNP, but not CNP. Importantly, stratified correlation analysis further revealed positive association between cGMP with ANP or BNP only in subjects with low, but not high, ANGII levels. In rats, co-infusion of ANGII even at physiological dose attenuated blood pressure reduction and cGMP generation triggered by ANP infusion. In vitro, we showed that the suppression effect of ANGII on ANP-stimulated cGMP requires the presence of ANGII type-1 (AT1) receptor and mechanistically involves protein kinase C (PKC), which can be substantially rescued by either valsartan (AT1 blocker) or Go6983 (PKC inhibitor). Using SPR, we showed ANGII has low affinity for particulate guanylyl cyclase A (GC-A) receptor binding compared to ANP or BNP.

Conclusions

Our study reveals ANGII as a natural suppressor for cGMP-generating action of GC-A via AT1/PKC dependent manner and highlights importance of dual-targeting RAAS and NPS in maximizing beneficial properties of natriuretic peptides in cardiovascular disease.

Cardiorenal Syndrome in the Hospital

The cardiorenal syndrome refers to a group of complex, bidirectional pathophysiological pathways involving dysfunction in both the heart and kidney. Upward of 60% of patients admitted for acute decompensated heart failure have CKD, as defined by an eGFR of <60 ml/min per 1.73 m2. CKD, in turn, is one of the strongest risk factors for mortality and cardiovascular events in acute decompensated heart failure. Although not well understood, the mechanisms in the cardiorenal syndrome include venous congestion, arterial underfilling, neurohormonal activation, inflammation, and endothelial dysfunction. Arterial underfilling may lead to activation of the renin-angiotensin-aldosterone system and sympathetic nervous system, leading to sodium reabsorption and vasoconstriction. Venous congestion likely also mediates and perpetuates these maladaptive pathways. To rule out intrinsic kidney disease that is distinct from the cardiorenal syndrome, one should obtain a careful history, review longitudinal eGFR trends, assess albuminuria and proteinuria, and review the urine sediment and kidney imaging. The hallmark of the cardiorenal syndrome is intense sodium avidity and diuretic resistance, often requiring a combination of diuretics with varying pharmacological targets, and monitoring of urinary response to guide escalations in therapy. Invasive means of decongestion may be required including ultrafiltration or kidney RRT such as peritoneal dialysis, which is often better tolerated from a hemodynamic perspective than intermittent hemodialysis. Strategies for increasing forward perfusion in states of low cardiac output and cardiogenic shock may include afterload reduction and inotropes and, in the most severe cases, mechanical circulatory support devices, many of which have kidney-specific considerations.

Guanylyl cyclase/natriuretic peptide receptor-A: Identification, molecular characterization, and physiological genomics

The natriuretic peptides (NPs) hormone family, which consists mainly of atrial, brain, and C-type NPs (ANP, BNP, and CNP), play diverse roles in mammalian species, ranging from renal, cardiac, endocrine, neural, and vascular hemodynamics to metabolic regulations, immune responsiveness, and energy distributions. Over the last four decades, new data has transpired regarding the biochemical and molecular compositions, signaling mechanisms, and physiological and pathophysiological functions of NPs and their receptors. NPs are incremented mainly in eliciting natriuretic, diuretic, endocrine, vasodilatory, and neurological activities, along with antiproliferative, antimitogenic, antiinflammatory, and antifibrotic responses. The main locus responsible in the biological and physiological regulatory actions of NPs (ANP and BNP) is the plasma membrane guanylyl cyclase/natriuretic peptide receptor-A (GC-A/NPRA), a member of the growing multi-limbed GC family of receptors. Advances in this field have provided tremendous insights into the critical role of Npr1 (encoding GC-A/NPRA) in the reduction of fluid volume and blood pressure homeostasis, protection against renal and cardiac remodeling, and moderation and mediation of neurological disorders. The generation and use of genetically engineered animals, including gene-targeted (gene-knockout and gene-duplication) and transgenic mutant mouse models has revealed and clarified the varied roles and pleiotropic functions of GC-A/NPRA in vivo in intact animals. This review provides a chronological development of the biochemical, molecular, physiological, and pathophysiological functions of GC-A/NPRA, including signaling pathways, genomics, and gene regulation in both normal and disease states.

Pleiotropic Roles of Atrial Natriuretic Peptide in Anti-Inflammation and Anti-Cancer Activity

Simple Summary

The relationship between inflammation and carcinogenesis, as well as the response to anti-tumor therapy, is intimate. Atrial natriuretic peptides (ANPs) play a pivotal role in the homeostatic control of blood pressure, electrolytes, and water balance. In addition, ANPs exert immune-modulatory effects in the tissue microenvironment, thus exhibiting a fascinating ability to prevent inflammation-related tumorigenesis and cancer recurrence. In cancers, ANPs show anti-proliferative effects through several molecular pathways. Furthermore, ANPs attenuate the side effects of cancer therapy. Therefore, ANPs have potential therapeutic value in tumors. Here, we summarized the roles of ANPs in diverse aspects of the immune system and the molecular mechanisms underlying the anti-cancer effects of ANPs, contributing to the development of ANP-based anti-cancer agents.

Abstract

The atrial natriuretic peptide (ANP), a cardiovascular hormone, plays a pivotal role in the homeostatic control of blood pressure, electrolytes, and water balance and is approved to treat congestive heart failure. In addition, there is a growing realization that ANPs might be related to immune response and tumor growth. The anti-inflammatory and immune-modulatory effects of ANPs in the tissue microenvironment are mediated through autocrine or paracrine mechanisms, which further suppress tumorigenesis. In cancers, ANPs show anti-proliferative effects through several molecular pathways. Furthermore, ANPs attenuate the side effects of cancer therapy. Therefore, ANPs act on several hallmarks of cancer, such as inflammation, angiogenesis, sustained tumor growth, and metastasis. In this review, we summarized the contributions of ANPs in diverse aspects of the immune system and the molecular mechanisms underlying the anti-cancer effects of ANPs.

Aldosterone and angiotensin II profiles in young black and white women using different hormonal contraceptives: the African-PREDICT study

Exogenous estrogens and progestins may affect the components of the renin-angiotensin-aldosterone system (RAAS). Changes in ventricular blood volume are associated with increased secretion of N-terminal pro-hormone B-type natriuretic peptide (NT-proBNP), which may also be affected by hormonal contraceptives. In this study, we aimed to compare components of the RAAS and NT-proBNP between groups using different hormonal contraceptives, including the combination pill, the injection or implant, and controls (no contraception) in black and white women of fertile age (20 - 30 years). Secondly, we determined whether blood pressure and NT-proBNP are associated with the RAAS components. We included 397 black and white women not using contraceptives, 120 using the combination pill, and 103 receiving an injection/implant. RAAS Triple-A analysis was carried out with LC-MS/MS quantification, and blood pressure measurements (ABPM) taken over 24 h. We found that serum aldosterone was higher (475.7 vs. 249.2 pmol/L; p < 0.001) in the combination pill group than in the no contraception group of white women. The aldosterone-angiotensin II ratio (AA2) was higher (5.4 vs. 2.5; p < 0.001) in the combination pill group than in the no contraception group. In the black women using the combination pill, we found a borderline-positive and borderline-negative association between 24-h systolic blood pressure and NT-proBNP with equilibrium (eq) Ang II, respectively. In white women using the combination pill, only CRP contributed positively and independently to NT-proBNP. To conclude, activation of RAAS by different hormonal contraceptives may increase future risk for the development of hypertension in young black and white women.

Mechanisms and Models in Heart Failure: A Translational Approach

Despite multiple attempts to develop a unifying hypothesis that explains the pathophysiology of heart failure with a reduced ejection fraction (HFrEF), no single conceptual model has withstood the test of time. In the present review, we discuss how the results of recent successful phase III clinical development programs in HFrEF are built upon existing conceptual models for drug development. We will also discuss where recent successes in clinical trials do not fit existing models to identify areas where further refinement of current paradigms may be needed. To provide the necessary structure for this review, we will begin with a brief overview of the pathophysiology of HFrEF, followed by an overview of the current conceptual models for HFrEF, and end with an analysis of the scientific rationale and clinical development programs for 4 new therapeutic classes of drugs that have improved clinical outcomes in HFrEF. The 4 new therapeutic classes discussed are ARNIs, SGLT2 (sodium-glucose cotransporter 2) inhibitors, soluble guanylate cyclase stimulators, and myosin activators. With the exception of SGLT2 inhibitors, each of these therapeutic advances was informed by the insights provided by existing conceptual models of heart failure. Although the quest to determine the mechanism of action of SGLT2 inhibitors is ongoing, this therapeutic class of drugs may represent the most important advance in cardiovascular therapeutics of recent decades and may lead to rethinking or expanding our current conceptual models for HFrEF.

Phosphodiesterase (1, 3 & 5) inhibitors attenuate diclofenac-induced acute kidney toxicity in rats

Diclofenac, one of the most commonly used non-steroidal anti-inflammatory drugs, leads to severe adverse effects on the kidneys. The aim of the present study was to investigate the potential pretreatment effect of phosphodiesterase (1, 3 & 5) inhibitors on diclofenac-induced acute renal failure in rats. Rats orally received pentoxifylline (100 mg/kg), vinpocetine (20 mg/kg), cilostazol (50 mg/kg), or sildenafil (5 mg/kg) once per day for 6 consecutive days. Diclofenac (15 mg/kg) was injected on day-4, -5 and -6 in all groups except normal control group. The used phosphodiesterase inhibitors significantly reduced the diclofenac-induced elevation in the serum levels of blood urea nitrogen, creatinine and cystatin C. Moreover, the renal tissue contents of tumor necrosis factor (TNF)-α, nuclear factor (NF)-κB as well as the protein expression of toll-like receptor (TLR) 4 and high mobility group box (HMGB) 1 were markedly reduced by the used phosphodiesterase inhibitors, as compared to the diclofenac control. This was reflected on the marked improvement in histopathological changes induced by diclofenac. Sildenafil showed the best protection regarding TNF-α and NF-κB, while cilostazol showed the best results regarding TLR4, HMGB1 and histopathological examination. This study revealed the good protective effect of these phosphodiesterase inhibitors against diclofenac-induced acute renal failure.

Risk-Based Approach for the Prediction and Prevention of Heart Failure

Targeted prevention of heart failure (HF) remains a critical need given the high prevalence of HF morbidity and mortality. Similar to risk-based prevention of atherosclerotic cardiovascular disease, optimal HF prevention strategies should include quantification of risk in the individual patient. In this review, we discuss incorporation of a quantitative risk-based approach into the existing HF staging landscape and the clinical opportunity that exists to translate available data on risk estimation to help guide personalized decision making. We first summarize the recent development of key HF risk prediction tools that can be applied broadly at a population level to estimate risk of incident HF. Next, we provide an in-depth description of the clinical utility of biomarkers to personalize risk estimation in select patients at the highest risk of developing HF. We also discuss integration of genomics-enhanced approaches (eg, Titin [TTN]) and other risk-enhancing features to reclassify risk with a precision medicine approach to HF prevention. Although sequential testing is very likely to identify low and high-risk individuals with excellent accuracy, whether or not interventions based on these risk models prevent HF in clinical practice requires prompt attention including randomized placebo-controlled trials of candidate therapies in risk-enriched populations. We conclude with a summary of unanswered questions and gaps in evidence that must be addressed to move the field of HF risk assessment forward.

New drugs for acute kidney injury

PURPOSE OF REVIEW

To describe recent advances in the development of therapeutic agents for acute kidney injury (AKI).

RECENT FINDINGS

Traditional care for AKI is mostly supportive. At present, no specific therapy has been developed to prevent or treat AKI. However, based on a better understanding of the pathophysiology of AKI, various potential compounds have been recently identified and tested. A variety of pathways has been targeted, including oxidative and mitochondrial stress, cellular metabolism and repair, inflammation, apoptosis and hemodynamics. Many of these potential agents are currently ongoing early-phase clinical trials, and the purpose of this review is to provide a summary of those with the most potential.

SUMMARY

Despite the lack of therapies specifically approved for AKI, many interesting potential agents are entering clinical trials, with the potential to transform the care of patients with AKI.

TaleNeprilysin and Neprilysin inhibition in chronic kidney disease

PURPOSE OF REVIEW

Chronic kidney disease (CKD) is associated with increased risk of progression to end-stage kidney disease and cardiovascular events. There is limited evidence that available treatments have beneficial effects on cardiorenal outcomes in all people with nondiabetic CKD. Neprilysin inhibition (NEPi) is a new therapeutic strategy with potential to improve outcomes for patients with CKD.

RECENT FINDINGS

NEPi enhances the activity of the natriuretic peptide system producing natriuresis, diuresis and inhibition of the renin-angiotensin system and sympathetic nervous system. Sacubitril/valsartan is the first Angiotensin receptor-neprilysin inhibitor (ARNI) to be produced and has been shown to substantially improve cardiovascular outcomes in heart failure and delay progression of kidney disease in this population. Although ARNIs have not shown similar effects on kidney function in the short-to-medium term in people with CKD, they are associated with substantial reductions in cardiac biomarkers and blood pressure in CKD.

SUMMARY

These data suggest that NEPi with an ARNI could benefit patients with CKD by reducing the risk of cardiovascular disease and have the possibility of retarding the progression of CKD (hence delaying the need for renal replacement therapy).

Biomarkers for Heart Failure Prognosis: Proteins, Genetic Scores and Non-coding RNAs

Heart failure (HF) is a complex disease in which cardiomyocyte injury leads to a cascade of inflammatory and fibrosis pathway activation, thereby causing decrease in cardiac function. As a result, several biomolecules are released which can be identified easily in circulating body fluids. The complex biological processes involved in the development and worsening of HF require an early treatment strategy to stop deterioration of cardiac function. Circulating biomarkers provide not only an ideal platform to detect subclinical changes, their clinical application also offers the opportunity to monitor disease treatment. Many of these biomarkers can be quantified with high sensitivity; allowing their clinical application to be evaluated beyond diagnostic purposes as potential tools for HF prognosis. Though the field of biomarkers is dominated by protein molecules, non-coding RNAs (microRNAs, long non-coding RNAs, and circular RNAs) are novel and promising biomarker candidates that encompass several ideal characteristics required in the biomarker field. The application of genetic biomarkers as genetic risk scores in disease prognosis, albeit in its infancy, holds promise to improve disease risk estimation. Despite the multitude of biomarkers that have been available and identified, the majority of novel biomarker candidates are not cardiac-specific, and instead may simply be a readout of systemic inflammation or other pathological processes. Thus, the true value of novel biomarker candidates in HF prognostication remains unclear. In this article, we discuss the current state of application of protein, genetic as well as non-coding RNA biomarkers in HF risk prognosis.

Natriuretic Peptides as the Basis of Peptide Drug Discovery for Cardiovascular Diseases

Cardiovascular diseases (CVDs) are the leading global cause of death, accounting for more than 17.6 million deaths per year in 2016, a number that is expected to grow to more than 23.6 million by 2030. While many technologies are currently under investigation to improve the therapeutic outcome of CVD complications, only a few medications have been approved. Therefore, new approaches to treat CVD are urgently required. Peptides regulate numerous physiological processes, mainly by binding to specific receptors and inducing a series of signals, neurotransmissions or the release of growth factors. Importantly, peptides have also been shown to play an important role in the circulatory system both in physiological and pathological conditions. Peptides, such as angiotensin II, endothelin, urotensin-II, urocortins, adrenomedullin and natriuretic peptides have been implicated in the control of vascular tone and blood pressure as well as in CVDs such as congestive heart failure, atherosclerosis, coronary artery disease, and pulmonary and systemic hypertension. Hence it is not surprising that peptides are becoming important therapeutic leads in CVDs. This article will review the current knowledge on peptides and their role in the circulatory system, focusing on the physiological roles of natriuretic peptides in the cardiovascular system and their implications in CVDs.

Cardiorenal syndrome: Multi-organ dysfunction involving the heart, kidney and vasculature

Cardiorenal syndrome (CRS) is a multi-organ disease, encompassing heart, kidney and vascular system dysfunction. CRS is a worldwide problem, with high morbidity, mortality, and inflicts a significant burden on the health care system. The pathophysiology is complex, involving interactions between neurohormones, inflammatory processes, oxidative stress and metabolic derangements. Therapies remain inadequate, mainly comprising symptomatic care with minimal prospect of full recovery. Challenges include limiting the contradictory effects of multi-organ targeted drug prescriptions and continuous monitoring of volume overload. Novel strategies such as multi-organ transplantation and innovative dialysis modalities have been considered but lack evidence in the CRS context. The adjunct use of pharmaceuticals targeting alternative pathways showing positive results in preclinical models also warrants further validation in the clinic. In recent years, studies have identified the involvement of gut dysbiosis, uraemic toxin accumulation, sphingolipid imbalance and other unconventional contributors, which has encouraged a shift in the paradigm of CRS therapy.

Neprilysin, the kidney brush border neutral proteinase: a possible potential target for ischemic renal injury

Neprilysin (NEP) is an endogenously induced peptidase for modulating production and degradation of various peptides in humans. It is most abundantly present in kidney and regulates the intrinsic renal homeostatic mechanism. Recently, drugs inhibiting NEP have been approved for the use in heart failure. In the context of increased prevalence of ischemia associated renal failure, NEP could be an attractive target for treating kidney failure. In the kidney, targeting NEP may possess potential benefits as well as adverse consequences. The unfavorable outcomes of NEP are mainly attributed to the degradation of the natriuretic peptides (NPs). NPs are involved in the inhibition of the renin-angiotensin-aldosterone system (RAAS) and activation of the sympathetic system contributing to the tubular and glomerular injury. In contrary, NEP exerts the beneficial effect by converting angiotensin-1 (Ang I) to angiotensin-(1-7) (Ang-(1-7)), thus activating MAS-related G-protein coupled receptor. MAS receptor antagonizes angiotensin type I receptor (AT-1R), reduces reactive oxygen species (ROS) and inflammation, thus ameliorating renal injury. However, the association of NEP with complex cascades of renal ischemia remains vague. Therefore, there is a need to evaluate the putative mechanism of NEP and its overlap with other signaling cascades in conditions of renal ischemia.

Cardiovascular Pleiotropic Effects of Natriuretic Peptides

Atrial natriuretic peptide (ANP) is a cardiac hormone belonging to the family of natriuretic peptides (NPs). ANP exerts diuretic, natriuretic, and vasodilatory effects that contribute to maintain water–salt balance and regulate blood pressure. Besides these systemic properties, ANP displays important pleiotropic effects in the heart and in the vascular system that are independent of blood pressure regulation. These functions occur through autocrine and paracrine mechanisms. Previous works examining the cardiac phenotype of loss-of-function mouse models of ANP signaling showed that both mice with gene deletion of ANP or its receptor natriuretic peptide receptor A (NPR-A) developed cardiac hypertrophy and dysfunction in response to pressure overload and chronic ischemic remodeling. Conversely, ANP administration has been shown to improve cardiac function in response to remodeling and reduces ischemia-reperfusion (I/R) injury. ANP also acts as a pro-angiogenetic, anti-inflammatory, and anti-atherosclerotic factor in the vascular system. Pleiotropic effects regarding brain natriuretic peptide (BNP) and C-type natriuretic peptide (CNP) were also reported. In this review, we discuss the current evidence underlying the pleiotropic effects of NPs, underlying their importance in cardiovascular homeostasis.

Obesity-related heart failure with preserved ejection fraction: new treatment strategies

OBJECTIVES

Obesity has risen in the US and worldwide, and has become a major risk factor for type 2 diabetes mellitus (T2DM), hypertension, cardiovascular disease, and mostly HF with preserved ejection fraction (HFpEF). Also, the prevalence of HF is quite high in the US accounting for 6.6 million adults at present and is projected to reach 8.5 million by the year 2030 and is equally divided between HFpEF and heart failure reduced ejection fraction (HFrEF). Patients with HFpEF are resistant to treatment with drugs usually used for the treatment of HFrEF, but the reasons for this resistance are not clearly known.

METHODS

In order to get a better perspective on the current status of the underlying pathophysiology and treatment of patients with HFpEF, a Medline search of the English language literature was conducted between 2015 and 2018 using the terms obesity, HFpEF, diabetes, treatment, SGLT2 inhibitors, and neprilysin inhibitors and 24 pertinent papers were selected.

RESULTS

The review of these papers revealed that patients with HFpEF have expanded plasma volume, restricted left ventricular distension with increased end-diastolic volume and depressed natriuretic peptide levels. In this respect, drugs that cause increased diuresis and natriuresis should a reasonable choice to treat these patients. The recently FDA approved sodium-glucose cotransporter-2 (SGLT2) inhibitors for the treatment of T2DM, are a good choice, for the treatment of HFpEF, since they cause osmotic diuresis from glucose excretion and increase salt and water excretion and decrease plasma volume. In addition, they produce loss of calories leading to weight and blood pressure reduction and have shown to prevent the new onset HFpEF and decrease hospitalizations and death from this disease.

CONCLUSION

The results of this analysis has shown that HFpEF has different pathophysiology from HFrEF and is difficult to treat. Drugs that block renal tubular glucose reabsorption and cause osmotic diuresis and natriuresis could be a good choice to treat patients with HFpEF alone or in combination with diuretics and other drugs.

Vagus nerve stimulation for the treatment of heart failure

Heart failure (HF) is one of the most prevalent cardiovascular diseases and is associated with high morbidity and mortality. Mechanistically, HF is characterized by an overactive sympathetic nervous system and parasympathetic withdrawal, and this autonomic imbalance contributes to the progression of the disease. As such, modulation of autonomic nervous system by device-based therapy is an attractive treatment target. In this review, we discuss the role of autonomic nervous system dysfunction in the pathogenesis of HF and present the available evidence regarding vagus nerve stimulation for HF, with special emphasis on optimization of stimulation parameters. Finally, we discuss future avenues of research for neuromodulation in patients with HF.

Low-dose atrial natriuretic peptide for prevention or treatment of acute kidney injury: a systematic review and meta-analysis

Background

Theoretically, atrial natriuretic peptide (ANP), especially low-dose ANP, is beneficial in acute kidney injury (AKI). In this study, we examined whether low-dose ANP is effective in preventing or treating AKI by conducting an updated systematic review for randomized controlled trials (RCTs).

Method

We searched the Excerpta Medica database (EMBASE), PubMed, and Cochrane CENTRAL databases for RCTs that compare the effects of low-dose ANP (≤ 50 ng/kg/min) with a placebo or conventional therapy in at-risk patients or patients with AKI. The primary outcome was the incidence of new AKI (in prevention RCTs), while the secondary outcomes were in-hospital mortality rate, renal replacement therapy (RRT) requirement, length of hospital and intensive care unit (ICU) stay, incidence of hypotension, and peak serum creatinine levels. The risk-of-bias was evaluated using the Cochrane Collaboration risk-of-bias tool. Trial sequential analysis (TSA) was used for each outcome of interest.

Results

A total of 18 RCTs (16 prevention and two treatment trials) fulfilled our inclusion criteria. In prevention RCTs, the incidence of new AKI was significantly low in the low-dose ANP group (relative risk [RR] = 0.51; 95% confidence interval [CI] = 0.36–0.72; P = 0.0001) compared to the control group. In addition, the low-dose ANP group showed a significantly reduced RRT requirement in both prevention (RR = 0.17; 95% CI = 0.04–0.64; P = 0.009) and treatment (RR = 0.43; 95% CI = 0.20–0.93; P = 0.03) RCTs. Among secondary outcomes, in some cases, low-dose ANP was associated with a reduction in ICU and in-hospital stay. The risk-of-bias assessment and TSA results indicated that the sample sizes and qualities of the RCTs were insufficient to conclude the efficacy of low-dose ANP.

Conclusion

Low-dose ANP might be effective in preventing or treating AKI. However, the evidence accumulated so far is not strong enough to demonstrate ANP’s beneficial effects. The next step is to elucidate the effects of low-dose ANP by conducting multicenter, high-quality, large-sample RCTs.

Trial registration

PROSPERO registry CRD42017068568. Registered 20 June 2017.

Electronic supplementary material

The online version of this article (10.1186/s13054-019-2330-z) contains supplementary material, which is available to authorized users.

N-Terminal pro C-Type Natriuretic Peptide (NTproCNP) and myocardial function in ageing

Ageing-related alterations in cardiovascular structure and function are commonly associated with chronic inflammation. A potential blood-based biomarker indicative of a chronic inflammatory state is N-Terminal Pro C-Type Natriuretic Peptide (NTproCNP). We aim to investigate associations between NTproCNP and ageing-related impairments in cardiovascular function. Community-based participants underwent same-day assessment of cardiovascular function and circulating profiles of plasma NTproCNP. Associations between cardiovascular and biomarker profiles were studied in adjusted models including standard covariates. We studied 93 participants (mean age 73 ± 5.3 years, 36 women), of whom 55 (59%) had impaired myocardial relaxation (ratio of peak velocity flow in early diastole E (m/s) to peak velocity flow in late diastole by atrial contraction A (m/s) <0.84). Participants with impaired myocardial relaxation were also found to have lower peak early phase filling velocity (0.6 ± 0.1 vs 0.7 ± 0.1, p < 0.0001) and higher peak atrial phase filling velocity (0.9 ± 0.1 vs 0.7 ± 0.1, p < 0.0001). NTproCNP levelswere significantly lower among participants with impaired myocardial relaxation (16.4% vs 39.5% with NTproCNP ≥ 19, p = 0.012). After multivariable adjustments, NTproCNP was independently associated with impaired myocardial relaxation (OR 2.99, 95%CI 1.12–8.01, p = 0.029). Community elderly adults with myocardial ageing have lower NTproCNP levels compared to those with preserved myocardial function. Given that impaired myocardial relaxation probably represents early changes within the myocardium with ageing, NTproCNP may be useful as an ‘upstream’ biomarker useful for charting myocardial ageing.

Hypertensive disorders of pregnancy and future heart failure risk: A nationwide population-based retrospective cohort study

OBJECTIVE

To assess whether hypertensive disorders of pregnancy (HDP) increased the risk of subsequent heart failure (HF) and identify possible risk factors.

STUDY DESIGN

A nationwide population-based retrospective cohort study.

MAIN OUTCOME MEASURES

Incidence of heart failure.

RESULTS

Among the 23.3 million individuals registered in the National Health Insurance Research Database in Taiwan, 29,186 patients with HDP and 116,744 matched controls were identified. The overall incidence of HF was greater in the HDP group than it was in the control group (9.83 vs. 1.67 per 10,000 person-years), with a significant incidence rate ratio (IRR = 5.88, 95% confidence interval [CI] 5.84-5.92, p < 0.0001). When stratified by age, parity, gestational age, gestational number, and follow-up years, the IRR for subsequent HF remained significantly higher in the HDP group in all stratifications. Additionally, the Kaplan-Meier analysis indicated that the cumulative incidence rate of HF was higher in the HDP group than it was in the control group. The Cox proportional-hazard model analysis showed that in addition to HDP, single parity, preterm and hypertension were independent risk factors for developing HF. Moreover, HF was more likely to develop within 5 years post-partum. Among patients with a history of HDP, the Cox proportional-hazard model showed that severe forms of HDP and increased HDP occurrences were independently associated with the subsequent development of HF.

CONCLUSIONS

Patients who have experienced HDP presented an increased risk for developing HF later in life. Moreover, among individuals with a history of HDP, those with severe forms of HDP or recurrent HDP displayed an increased subsequent risk of HF.

Natriuretic Peptides in Heart Failure: Atrial and B-type Natriuretic Peptides

The natriuretic peptides play a vital role in normal physiology and as counter-regulatory hormones in heart failure (HF). Clinical assessment of their levels (for B-type natriuretic peptide [BNP], N-terminal proBNP, and the midregion of N-terminal pro-atrial natriuretic peptide) have become valuable tools in diagnosing patients with HF as well as risk stratifying and guiding therapy. Their roles have further expanded beyond HF to other cardiovascular conditions and for risk stratification in asymptomatic individuals. Understanding the clinical use of these hormones is vital to achieving their full potential.

Particulate Guanylyl Cyclase A/cGMP Signaling Pathway in the Kidney: Physiologic and Therapeutic Indications

The particulate guanylyl cyclase A (pGC-A)/cGMP pathway plays important roles in regulating renal physiological function and as well as in counteracting pathophysiological conditions. Naturally occurring peptide pGC-A activators consist of atrial natriuretic peptide (ANP), b-type NP (BNP), and urodilatin (URO). These activators bind and activate pGC-A, generating the second messenger cyclic 3′,5′ guanosine monophosphate (cGMP). Cyclic GMP binds to downstream pathway effector molecules including protein kinase G (PKG), cGMP-gated ion channels, and phosphodiesterases (PDEs). These mediators result in a variety of physiological actions in the kidney, including diuresis, natriuresis, increased glomerular filtration rate (GFR) and organ protection, thus, opposing renal cellular injury and remodeling. Downstream proteins regulated by PKG include collagen 1 (Col-1), transforming growth factor beta (TGF-β) and apoptosis-related proteins. In addition to their physiological regulatory effects, pGC-A/cGMP signaling is critical for preserving renal homeostasis in different renal diseases such as acute kidney injury (AKI). Regarding therapeutic options, native pGC-A activators have short half-lives and their activity can be further enhanced by advances in innovative peptide engineering. Thus, novel designer peptide pGC-A activators with enhanced renal activity are under development.

Decoding the molecular switches of natriuretic peptides which differentiate its vascular and renal functions

Heart failure (HF) is associated with high morbidity and mortality. Dysfunction of blood pressure and/or volume homeostatic processes result in lower perfusion and/or congestion. Treatment strategies exerting differential effects on pressure and volume mechanisms are critical in handling patients with HF. Atrial natriuretic peptides (ANPs) are a key hormone in maintaining circulation. It binds to NP receptor-A (NPR-A) on vasculature, kidneys and nervous system to lowers blood pressure and volume. It exerts a concentration-dependent pharmacological activity, and only increased renal excretion of water and sodium at low doses and vasodilation along with renal effects at slightly higher doses. Recently, we showed that K-Ring (conserved ring of krait venom NP) elicited only vasodilatory properties despite its ability to evoke NPR-A. Through systematic analysis of the structure-function relationships of K-Ring, we have delineated the molecular switches that control vasodilatory and diuretic properties of NPs in anesthetized rats. In the process, we have identified residues that - (a) differentiate vascular and renal functions, (b) affect heart rate and pulse pressure, (c) exhibit sustained effect on vasodilatory function and (d) forceful diuresis switches. Furthermore, we have shown these residues to have equivalent effects on ANP scaffold, thereby introducing modularity in designing function-based ANP analogs. By comparing the ability of designed NPs to evoke cGMP levels, we propose a hypothetical mechanism for the observed tissue-specific effects. The present study opens new avenues in the development of suitable therapeutic agents for personalized care for HF patients.

Altered heart rate regulation by the autonomic nervous system in mice lacking natriuretic peptide receptor C (NPR-C)

Natriuretic peptides (NPs) play essential roles in the regulation of cardiovascular function. NP effects are mediated by receptors known as NPR-A, NPR-B or NPR-C. NPs have potent effects on regulation of heart rate (HR) by the autonomic nervous system (ANS), but the role of NPR-C in these effects has not been investigated. Accordingly, we have used telemetric ECG recordings in awake, freely moving wildtype and NPR-C knockout (NPR-C^−/−) mice and performed heart rate variability (HRV) analysis to assess alterations in sympatho-vagal balance on the heart following loss of NPR-C. Our novel data demonstrate that NPR-C^−/− mice are characterized by elevations in HR, reductions in circadian changes in HR and enhanced occurrence of sinus pauses, indicating increased arrhythmogenesis and a loss of HRV. Time domain and frequency domain analyses further demonstrate that HRV is reduced in NPR-C^−/− mice in association with a reduction in parasympathetic activity. Importantly, the low frequency to high frequency ratio was increased in NPR-C^−/− mice indicating that sympathetic activity is also enhanced. These changes in autonomic regulation were confirmed using atropine and propranolol to antagonize the ANS. These findings illustrate that loss of NPR-C reduces HRV due to perturbations in the regulation of the heart by the ANS.

CRRL269: a novel designer and renal-enhancing pGC-A peptide activator

The natriuretic peptides (NPs) B-type NP (BNP) and urodilatin (URO) exert renal protective properties via the particulate guanylyl cyclase A receptor (pGC-A). As a potential renal-enhancing strategy, we engineered a novel designer peptide that we call CRRL269. CRRL269 was investigated in human cell lines and in normal canines to define potential cardiorenal enhancing actions. The mechanism of its cardiorenal selective properties was also investigated. In vitro NP receptor activity was quantified with guanosine 3',5'-cyclic monophosphate generation. In vivo effects were determined in normal canine acute infusion studies. We observed that CRRL269 demonstrated enhanced pGC-A activity in renal compared with nonrenal cell lines. CRRL269 exerted enhanced resistance to neprilysin compared with URO. Importantly, CRRL269 exhibited significant and greater increases in urinary sodium excretion and diuresis, with less blood pressure reduction, than BNP or URO in normal canines. CRRL269 retained potent renin-angiotensin-aldosterone system (RAAS) suppressing properties shared by URO and BNP. Also, CRRL269 exerted less arterial relaxation and higher cAMP cardiomyocytes generation than BNP. CRRL269 possessed superior renal and pGC-A activating properties compared with BNP or URO in vitro. CRRL269 exerted enhanced renal actions while suppressing RAAS in vivo and with less hypotension compared with URO or BNP. Together, our study suggests that CRRL269 is a promising innovative renal-enhancing drug, with favorable protective actions targeting cardiorenal disease states through the pGC-A receptor.

Endothelial glycocalyx: basic science and clinical implications

The classic Starling principle proposed that microvascular fluid exchange was determined by a balance of hydrostatic and oncotic pressures relative to the vascular wall and this movement of water was regulated by gaps in the intercellular spaces. However, current literature on the endothelial glycocalyx (a jelly-like protective layer covering the luminal surface of the endothelium) has revised Starling's traditional concepts. This article aims to summarise the literature on the glycocalyx related to its basic science, clinical settings inciting injury, protective strategies and clinical perspectives. Perioperative damage to the glycocalyx structure can increase vascular permeability leading to interstitial fluid shifts, oedema, and increased surgical morbidity. Pathological shedding of the glycocalyx occurs in response to mechanical cellular stress, endotoxins, inflammatory mediators, atrial natriuretic peptide, ischaemia-reperfusion injury, free oxygen radicals and hyperglycaemia. Increased understanding of the endothelial glycocalyx may change perioperative fluid management, and therapeutic strategies aimed at its preservation may improve patient outcomes.

Pharmacokinetic, pharmacodynamic, and antihypertensive effects of the neprilysin inhibitor LCZ-696: sacubitril/valsartan

LCZ-696, sacubitril/valsartan, is a dual-acting molecule consisting of the angiotensin II (Ang II) receptor blocker valsartan and the neprilysin (neutral endopeptidase) inhibitor AHU-377 with significant beneficial effects in patients with hypertension and heart failure (HF). Several recent studies have demonstrated a higher effectiveness of LCZ-696 compared to valsartan in the treatment of hypertension and HF. The rationale for the development and the Food and Drug Administration approval of LCZ-696 was based on the concept of an additive effect of the Ang II receptor blocker valsartan and the neutral endopeptidase (neprilysin) inhibitor AHU-377 for the treatment of hypertension and HF. The synergism from these drugs arises from the vasodilating effects of valsartan through its blockade of Ang II type 1 receptor and the action of natriuretic peptides atrial natriuretic peptide and B-type natriuretic peptide (BNP) by preventing their catabolism with neprilysin resulting in increase of cyclic guanosine monophosphate. This action of neprilysin is associated with increased natriuresis, diuresis, and systemic vasodilation, since these peptides have been shown to have potent diuretic, natriuretic, and vasodilating effects. In addition, it reduces the levels of N terminal pro-BNP. Therefore, administration of LCZ-696 results in significant reduction of wall stress from pressure and volume overload of the left ventricle as demonstrated by the reduction of N terminal pro-BNP, both significant constituents of hypertension and HF, and it is safe, well tolerated and is almost free of cough and angioedema.

C-type natriuretic peptide and natriuretic peptide receptor B signalling inhibits cardiac sympathetic neurotransmission and autonomic function

Aims

B-type natriuretic peptide (BNP)–natriuretic peptide receptor A (NPR-A) receptor signalling inhibits cardiac sympathetic neurotransmission, although C-type natriuretic peptide (CNP) is the predominant neuropeptide of the nervous system with expression in the heart and vasculature. We hypothesized that CNP acts similarly to BNP, and that transgenic rats (TGRs) with neuron-specific overexpression of a dominant negative NPR-B receptor would develop heightened sympathetic drive.

Methods and results

Mean arterial pressure and heart rate (HR) were significantly (P < 0.05) elevated in freely moving TGRs (n = 9) compared with Sprague Dawley (SD) controls (n = 10). TGR had impaired left ventricular systolic function and spectral analysis of HR variability suggested a shift towards sympathoexcitation. Immunohistochemistry demonstrated co-staining of NPR-B with tyrosine hydroxylase in stellate ganglia neurons. In SD rats, CNP (250 nM, n = 8) significantly reduced the tachycardia during right stellate ganglion stimulation (1–7 Hz) in vitro whereas the response to bath-applied norepinephrine (NE, 1 μM, n = 6) remained intact. CNP (250 nM, n = 8) significantly reduced the release of ³H-NE in isolated atria and this was prevented by the NPR-B antagonist P19 (250 nM, n = 6). The neuronal Ca²⁺ current (n = 6) and intracellular Ca²⁺ transient (n = 9, using fura-2AM) were also reduced by CNP in isolated stellate neurons. Treatment of the TGR (n = 9) with the sympatholytic clonidine (125 µg/kg per day) significantly reduced mean arterial pressure and HR to levels observed in the SD (n = 9).

Conclusion

C-type natriuretic peptide reduces cardiac sympathetic neurotransmission via a reduction in neuronal calcium signalling and NE release through the NPR-B receptor. Situations impairing CNP–NPR-B signalling lead to hypertension, tachycardia, and impaired left ventricular systolic function secondary to sympatho-excitation.

Genetic Analysis of the Atrial Natriuretic Peptide Gene Polymorphisms among Essential Hypertensive Patients in Malaysia

Background. Atrial natriuretic peptide (ANP) considerably influences blood pressure regulation through water and sodium homoeostasis. Several of the studies have utilized anonymous genetic polymorphic markers and made inconsequent claims about the ANP relevant disorders. Thus, we screened Insertion/Deletion (ID) and G191A polymorphisms of ANP to discover sequence variations with potential functional significance and to specify the linkage disequilibrium pattern between polymorphisms. The relationships of detected polymorphisms with EH with or without Type 2 Diabetes Mellitus (T2DM) status were tested subsequently. Method. ANP gene polymorphisms (I/D and A191G) were specified utilizing mutagenically separated Polymerase Chain Reaction (PCR) in 320 subjects including 163 EH case subjects and 157 controls. Result. This case-control study discovered a significant association between I/D polymorphisms of ANP gene in EH patient without T2DM. However, the study determined no association between G191A polymorphisms of ANP in EH with or without T2DM. In addition, sociodemographic factors in the case and healthy subjects exhibited strong differences (P < 0.05). Conclusion. As a risk factor, ANP gene polymorphisms may affect hypertension. Despite the small sample size in this study, it is the first research assessing the ANP gene polymorphisms in both EH and T2DM patients among Malaysian population.

Brain natriuretic peptide: Much more than a biomarker

Brain natriuretic peptide (BNP) modulates several biological processes by activating the natriuretic peptide receptor A (NPR-A). Atria and ventricles secrete BNP. BNP increases natriuresis, diuresis and vasodilatation, thus resulting in a decreased cardiac workload. BNP and NT-proBNP, which is the biologically inactive N-terminal portion of its pro-hormone, are fast and sensitive biomarkers for diagnosing heart failure. The plasma concentrations of both BNP and NT-proBNP also correlate with left ventricular function in patients with acute exacerbation of COPD, even without history of heart failure. Several studies have been conducted in vitro and in vivo, both in animals and in humans, in order to assess the potential role of the NPR-A activation as a novel therapeutic approach for treating obstructive pulmonary disorders. Unfortunately, these studies have yielded conflicting results. Nevertheless, further recent specific studies, performed in ex vivo models of asthma and COPD, have confirmed the bronchorelaxant effect of BNP and its protective role against bronchial hyperresponsiveness in human airways. These studies have also clarified the intimate mechanism of action of BNP, represented by an autocrine loop elicited by the activation of NPR-A, localized on bronchial epithelium, and the relaxant response of the surrounding ASM, which does not expresses NPR-A. This review explores the teleological activities and paradoxical effects of BNP with regard to chronic obstructive respiratory disorders, and provides an excursus on the main scientific findings that explain why BNP should be considered much more than a biomarker.

Cardiac fibrosis in myocardial infarction-from repair and remodeling to regeneration

Ischemic cell death during a myocardial infarction leads to a multiphase reparative response in which the damaged tissue is replaced with a fibrotic scar produced by fibroblasts and myofibroblasts. This also induces geometrical, biomechanical, and biochemical changes in the uninjured ventricular wall eliciting a reactive remodeling process that includes interstitial and perivascular fibrosis. Although the initial reparative fibrosis is crucial for preventing rupture of the ventricular wall, an exaggerated fibrotic response and reactive fibrosis outside the injured area are detrimental as they lead to progressive impairment of cardiac function and eventually to heart failure. In this review, we summarize current knowledge of the mechanisms of both reparative and reactive cardiac fibrosis in response to myocardial infarction, discuss the potential of inducing cardiac regeneration through direct reprogramming of fibroblasts and myofibroblasts into cardiomyocytes, and review the currently available and potential future therapeutic strategies to inhibit cardiac fibrosis. Graphical abstract Reparative response following a myocardial infarction. Hypoxia-induced cardiomyocyte death leads to the activation of myofibroblasts and a reparative fibrotic response in the injured area. Right top In adult mammals, the fibrotic scar formed at the infarcted area is permanent and promotes reactive fibrosis in the uninjured myocardium. Right bottom In teleost fish and newts and in embryonic and neonatal mammals, the initial formation of a fibrotic scar is followed by regeneration of the cardiac muscle tissue. Induction of post-infarction cardiac regeneration in adult mammals is currently the target of intensive research and drug discovery attempts.

Combining angiotensin II receptor 1 antagonism and neprilysin inhibition for the treatment of heart failure

Sacubitril/valsartan is a novel, first-in-class drug, which combines a neprilysin inhibitor with an angiotensin receptor blocker. Sacubitril inhibits neprilysin endopeptidase, blocking the catabolism of natriuretic peptides (NP), thereby increasing their bioavailability. Valsartan counterbalances the increase of angiotensin II that results from neprilysin inhibition, exerting also the beneficial effects of angiotensin receptor blockers seen in previous HF trials. PARADIGM-HF trial has proved the superiority of sacubitril/valsartan (LCZ696) over ACE inhibitor enalapril to reduce mortality and morbidity of symptomatic HF patients with reduced ejection fraction (HFrEF), setting the grounds for the replacement of ACE inhibitors by sacubitril/valsartan in the management of HFrEF. Sacubitril/valsartan is currently being tested in a phase III trial (PARAGON-HF) in patients with HF with preserved EF. PARAGON-HF is also expected to provide further data regarding the long-term safety of sacubitril/valsartan, hopefully to alleviate concerns regarding the effects of neprilysin inhibition on cognitive function.

A Review of New Pharmacologic Treatments for Patients With Chronic Heart Failure With Reduced Ejection Fraction

Heart failure (HF) impacts an estimated 5.7 million Americans, and its prevalence is projected to increase to more than 8 million Americans in the next 15 years. Key clinical trials have established an evidence-based foundation for treatment of heart failure with reduced ejection fraction (HFrEF). Ivabradine and sacubitril/valsartan, which inhibit the f-channel and the angiotensin receptor and neprilysin, respectively, were recently approved by the Food and Drug Administration for HFrEF. In systolic heart failure, treatment with the If inhibitor ivabradine significantly reduced the combined endpoint of cardiovascular mortality or heart failure hospital admission vs placebo (P < .05). In the Prospective Comparison of angiotensin receptor-neprilysin inhibitor (ARNI) with angiotensin-converting enzyme inhibitor (ACEI) to Determine Impact on Global Mortality and Morbidity in Heart Failure trial, sacubitril/valsartan significantly reduced the combined endpoint of cardiovascular death or heart failure hospitalization vs enalapril (P < .001). The place of therapy with ivabradine and sacubitril/valsartan is defined by these trials and their interplay with guideline-directed medical therapy. Ivabradine and sacubitril/valsartan increase pharmacotherapy options for the treatment of HFrEF but are not yet first-line agents. Clinical application will be better defined in the coming years as practitioners increase their familiarity with ivabradine and sacubitril/valsartan.

The utility of cardiac biomarkers and echocardiography for the early detection of bevacizumab- and sunitinib-mediated cardiotoxicity

The recent introduction of novel anticancer therapies, including bevacizumab (BVZ) and sunitinib (SNT), is associated with an increased risk of cardiotoxicity. However, early identification of left ventricular (LV) systolic dysfunction may facilitate dose modification and avoid the development of advanced heart failure. Using a murine model of BVZ- and SNT-mediated cardiotoxicity, we investigated whether cardiac biomarkers and/or tissue velocity imaging (TVI) using echocardiography can detect early changes in cardiac function, before a decrease in LV ejection fraction is identified. A total of 75 wild-type C57Bl/6 male mice were treated with either 0.9% saline, BVZ, or SNT. Serial monitoring of blood pressure, high-sensitivity troponin I, and echocardiographic indexes were performed over a 14-day study period, after which the mice were euthanized for histological and biochemical analyses. Mice treated with either BVZ or SNT developed systemic hypertension as early as day 7, which increased by day 14. Cardiac biomarkers, specifically high-sensitivity troponin I, were not predictive of early LV systolic dysfunction. Although conventional LV ejection fraction values decreased at day 13 in mice treated with either BVZ or SNT, TVI confirmed early LV systolic dysfunction at day 8. Histological and biochemical analysis demonstrated loss of cellular integrity, increased oxidative stress, and increased cardiac apoptosis in mice treated with BVZ or SNT therapy at day 14. In a murine model of BVZ- or SNT-mediated cardiomyopathy, noninvasive assessment by TVI detected early LV systolic dysfunction before alterations in conventional echocardiographic indexes.

Tail wags the dog: activity of krait natriuretic peptide is determined by its C-terminal tail in a natriuretic peptide receptor-independent manner

Action mechanism of a novel natriuretic peptide from snake venom.

Evolution of biomarker guided therapy for heart failure: current concepts and trial evidence

Optimizing management of patients with heart failure remains quite challenging despite many significant advances in drug and device therapy for this syndrome. Although a large body of evidence from robust clinical trials supports multiple thera-pies, utilization of these well-established treatments remains inconsistent and outcomes suboptimal in “real-world” patients with heart failure. Disease management programs may be effective, but are difficult to implement due to cost and logistical issues. Another approach to optimizing therapy is to utilize biomarkers to guide therapeutic choices. Natriuretic peptides pro-vide additional information of significant clinical value in the diagnosis and estimation of risk inpatients with heart failure. Ongoing research suggests a potential important added role for natriuretic peptides in heart failure. Guiding therapy based on serial changes in these biomarkers may be an effective strategy to optimize treatment and achieve better outcomes in this syn-drome. Initial, innovative, proof-of-concept studies have provided encouraging results and important insights into key as-pects of this strategy, but well designed, large-scale, multicenter, randomized, outcome trials are needed to definitively estab-lish this novel approach to management. Given the immense and growing public health burden of heart failure, identification of cost-effective ways to decrease the morbidity and mortality due to this syndrome is critical.

Efficacy of B-Type Natriuretic Peptide Is Coupled to Phosphodiesterase 2A in Cardiac Sympathetic Neurons

Elevated B-type natriuretic peptide (BNP) regulates cGMP-phosphodiesterase activity. Its elevation is regarded as an early compensatory response to cardiac failure where it can facilitate sympathovagal balance and cardiorenal homeostasis. However, recent reports suggest a paradoxical proadrenergic action of BNP. Because phosphodiesterase activity is altered in cardiovascular disease, we tested the hypothesis that BNP might lose its efficacy by minimizing the action of cGMP on downstream pathways coupled to neurotransmission. BNP decreased norepinephrine release from atrial preparations in response to field stimulation and also significantly reduced the heart rate responses to sympathetic nerve stimulation in vitro. Using electrophysiological recording and fluorescence imaging, BNP also reduced the depolarization evoked calcium current and intracellular calcium transient in isolated cardiac sympathetic neurons. Pharmacological manipulations suggested that the reduction in the calcium transient was regulated by a cGMP/protein kinase G pathway. Fluorescence resonance energy transfer measurements for cAMP, and an immunoassay for cGMP, showed that BNP increased cGMP, but not cAMP. In addition, overexpression of phosphodiesterase 2A after adenoviral gene transfer markedly decreased BNP stimulation of cGMP and abrogated the BNP responses to the calcium current, intracellular calcium transient, and neurotransmitter release. These effects were reversed on inhibition of phosphodiesterase 2A. Moreover, phosphodiesterase 2A activity was significantly elevated in stellate neurons from the prohypertensive rat compared with the normotensive control. Our data suggest that abnormally high levels of phosphodiesterase 2A may provide a brake against the inhibitory action of BNP on sympathetic transmission.

Intrinsic defence capacity and therapeutic potential of natriuretic peptides in pulmonary hypertension associated with lung fibrosis

BACKGROUND AND PURPOSE

Idiopathic pulmonary fibrosis (IPF) is a progressive fibro-proliferative disorder refractory to current therapy commonly complicated by the development of pulmonary hypertension (PH); the associated morbidity and mortality are substantial. Natriuretic peptides possess vasodilator and anti-fibrotic actions, and pharmacological augmentation of their bioactivity ameliorates renal and myocardial fibrosis. Here, we investigated whether natriuretic peptides possess an intrinsic cytoprotective function preventing the development of pulmonary fibrosis and associated PH, and whether therapeutics targeting natriuretic peptide signalling demonstrate efficacy in this life-threatening disorder.

EXPERIMENTAL APPROACH

Pulmonary haemodynamics, right ventricular function and markers of lung fibrosis were determined in wild-type (WT) and natriuretic peptide receptor (NPR)-A knockout (KO) mice exposed to bleomycin (1 mg·kg⁻¹). Human myofibroblast differentiation was studied in vitro.

KEY RESULTS

Exacerbated cardiac, vascular and fibrotic pathology was observed in NPR-A KO animals, compared with WT mice, exposed to bleomycin. Treatment with a drug combination that raised circulating natriuretic peptide levels (ecadotril) and potentiated natriuretic peptide-dependent signalling (sildenafil) reduced indices of disease progression, whether administered prophylactically or to animals with established lung disease. This positive pharmacodynamic effect was diminished in NPR-A KO mice. Atrial natriuretic peptide and sildenafil synergistically reduced TGFβ-induced human myofibroblast differentiation, a key driver of remodelling in IPF patients.

CONCLUSIONS AND IMPLICATIONS

These data highlight an endogenous host-defence capacity of natriuretic peptides in lung fibrosis and PH. A combination of ecadotril and sildenafil reversed the pulmonary haemodynamic aberrations and remodelling that characterize the disease, advocating therapeutic manipulation of natriuretic peptide bioactivity in patients with IPF.

Natriuretic peptide receptor 3 (NPR3) is regulated by microRNA-100

Natriuretic peptide receptor 3 (NPR3) is the clearance receptor for the cardiac natriuretic peptides (NPs). By modulating the level of NPs, NPR3 plays an important role in cardiovascular homeostasis. Although the physiological functions of NPR3 have been explored, little is known about its regulation in health or disease. MicroRNAs play an essential role in the post-transcriptional expression of many genes. Our aim was to investigate potential microRNA-based regulation of NPR3 in multiple models. Hypoxic challenge elevated levels of NPPB and ADM mRNA, as well as NT-proBNP and MR-proADM in human left ventricle derived cardiac cells (HCMa), and in the corresponding conditioned medium, as revealed by qRT-PCR and ELISA. NPR3 was decreased while NPR1 was increased by hypoxia at mRNA and protein levels in HCMa. Down-regulation of NPR3 mRNA was also observed in infarct and peri-infarct cardiac tissue from rats undergoing myocardial infarction. From microRNA microarray analyses and microRNA target predictive databases, miR-100 was selected as a candidate regulator of NPR3 expression. Further analyses confirmed up-regulation of miR-100 in hypoxic cells and associated conditioned media. Antagomir-based silencing of miR-100 enhanced NPR3 expression in HCMa. Furthermore, miR-100 levels were markedly up-regulated in rat hearts and in peripheral blood after myocardial infarction and in the blood from heart failure patients. Results from this study point to a role for miR-100 in the regulation of NPR3 expression, and suggest a possible therapeutic target for modulation of NP bioactivity in heart disease.