Current role of neprilysin inhibitors in hypertension and heart failure

The renin-angiotensin-aldosterone system: An old tree sprouts new shoots

The intricate physiological and pathological diversity of the Renin-Angiotensin-Aldosterone System (RAAS) underpins its role in maintaining bodily equilibrium. This paper delves into the classical axis (Renin-ACE-Ang II-AT1R axis), the protective arm (ACE2-Ang (1-7)-MasR axis), the prorenin-PRR-MAP kinases ERK1/2 axis, and the Ang IV-AT4R-IRAP cascade of RAAS, examining their functions in both physiological and pathological states. The dysregulation or hyperactivation of RAAS is intricately linked to numerous diseases, including cardiovascular disease (CVD), renal damage, metabolic disease, eye disease, Gastrointestinal disease, nervous system and reproductive system diseases. This paper explores the pathological mechanisms of RAAS in detail, highlighting its significant role in disease progression. Currently, in addition to traditional drugs like ACEI, ARB, and MRA, several novel therapeutics have emerged, such as angiotensin receptor-enkephalinase inhibitors, nonsteroidal mineralocorticoid receptor antagonists, aldosterone synthase inhibitors, aminopeptidase A inhibitors, and angiotensinogen inhibitors. These have shown potential efficacy and application prospects in various clinical trials for related diseases. Through an in-depth analysis of RAAS, this paper aims to provide crucial insights into its complex physiological and pathological mechanisms and offer valuable guidance for developing new therapeutic approaches. This comprehensive discussion is expected to advance the RAAS research field and provide innovative ideas and directions for future clinical treatment strategies.

Identification of senescence related hub genes and potential therapeutic compounds for dilated cardiomyopathy via comprehensive transcriptome analysis

BACKGROUND

Dilated cardiomyopathy (DCM) is a common cause of heart failure. However, the role of cellular senescence in DCM has not been fully elucidated. Here, we aimed to investigate senescence in DCM, identify senescence related characteristic genes, and explore the potential small molecule compounds for DCM treatment.

METHODS

DCM-associated datasets and senescence-related genes were respectively obtained from Gene Expression Omnibus (GEO) database and CellAge database. The characteristic genes were identified through methods including weighted gene co-expression network analysis (WGCNA), least absolute shrinkage and selection operator (LASSO), and random forest. The expression of characteristic genes was verified in the mouse DCM model. Moreover, the CIBERSORT algorithm was applied to analyze immune characteristics of DCM. Finally, several therapeutic compounds were predicted by CMap analysis, and the potential mechanism of chlorogenic acid (CGA) was investigated by molecular docking and molecular dynamics simulation.

RESULTS

Three DCM- and senescence-related characteristic genes (MME, GNMT and PLA2G2A) were ultimately identified through comprehensive transcriptome analysis, and were experimentally verified in the doxorubicin induced mouse DCM. Meanwhile, the established diagnostic model, derived from dataset analysis, showed ideal diagnostic performance for DCM. Immune cell infiltration analysis suggested dysregulation of inflammation in DCM, and the characteristic genes were significantly associated with invasive immune cells. Finally, based on the specific gene expression profile of DCM, several potential therapeutic compounds were predicted through CMap analysis. In addition, molecular docking and molecular dynamics simulations suggested that CGA could bind to the active pocket of MME protein.

CONCLUSION

Our study presents three characteristic genes (MME, PLA2G2A, and GNMT) and a novel senescence-based diagnostic nomogram, and discusses potential therapeutic compounds, providing new insights into the diagnosis and treatment of DCM.

Multi-Target In-Silico modeling strategies to discover novel angiotensin converting enzyme and neprilysin dual inhibitors

Cardiovascular diseases, including heart failure, stroke, and hypertension, affect 608 million people worldwide and cause 32% of deaths. Combination therapy is required in 60% of patients, involving concurrent Renin-Angiotensin-Aldosterone-System (RAAS) and Neprilysin inhibition. This study introduces a novel multi-target in-silico modeling technique (mt-QSAR) to evaluate the inhibitory potential against Neprilysin and Angiotensin-converting enzymes. Using both linear (GA-LDA) and non-linear (RF) algorithms, mt-QSAR classification models were developed using 983 chemicals to predict inhibitory effects on Neprilysin and Angiotensin-converting enzymes. The Box-Jenkins method, feature selection method, and machine learning algorithms were employed to obtain the most predictive model with ~ 90% overall accuracy. Additionally, the study employed virtual screening of designed scaffolds (Chalcone and its analogues, 1,3-Thiazole, 1,3,4-Thiadiazole) applying developed mt-QSAR models and molecular docking. The identified virtual hits underwent successive filtration steps, incorporating assessments of drug-likeness, ADMET profiles, and synthetic accessibility tools. Finally, Molecular dynamic simulations were then used to identify and rank the most favourable compounds. The data acquired from this study may provide crucial direction for the identification of new multi-targeted cardiovascular inhibitors.

Advances in extracellular vesicles as mediators of cell-to-cell communication in pregnancy

Cell-to-cell communication mediated by Extracellular Vesicles (EVs) is a novel and emerging area of research, especially during pregnancy, in which placenta derived EVs can facilitate the feto-maternal communication. EVs comprise a heterogeneous group of vesicle sub-populations with diverse physical and biochemical characteristics and originate by specific biogenesis mechanisms. EVs transfer molecular cargo (including proteins, nucleic acids, and lipids) between cells and are critical mediators of cell communication. There is growing interest among researchers to explore into the molecular cargo of EVs and their functions in a physiological and pathological context. For example, inflammatory mediators such as cytokines are shown to be released in EVs and EVs derived from immune cells play key roles in mediating the immune response as well as immunoregulatory pathways. Pregnancy complications such as gestational diabetes mellitus, preeclampsia, intrauterine growth restriction and preterm birth are associated with altered levels of circulating EVs, with differential EV cargo and bioactivity in target cells. This implicates the intriguing roles of EVs in reprogramming the maternal physiology during pregnancy. Moreover, the capacity of EVs to carry bioactive molecules makes them a promising tool for biomarker development and targeted therapies in pregnancy complications. This review summarizes the physiological and pathological roles played by EVs in pregnancy and pregnancy-related disorders and describes the potential of EVs to be translated into clinical applications in the diagnosis and treatment of pregnancy complications.

The recent advance and prospect of natural source compounds for the treatment of heart failure

Heart failure is a continuously developing syndrome of cardiac insufficiency caused by diseases, which becomes a major disease endangering human health as well as one of the main causes of death in patients with cardiovascular diseases. The occurrence of heart failure is related to hemodynamic abnormalities, neuroendocrine hormones, myocardial damage, myocardial remodeling etc, lead to the clinical manifestations including dyspnea, fatigue and fluid retention with complex pathophysiological mechanisms. Currently available drugs such as cardiac glycoside, diuretic, angiotensin-converting enzyme inhibitor, vasodilator and β receptor blocker etc are widely used for the treatment of heart failure. In particular, natural products and related active ingredients have the characteristics of mild efficacy, low toxicity, multi-target comprehensive efficacy, and have obvious advantages in restoring cardiac function, reducing energy disorder and improving quality of life. In this review, we mainly focus on the recent advance including mechanisms and active ingredients of natural products for the treatment of heart failure, which will provide the inspiration for the development of more potent clinical drugs against heart failure.

Vascular smooth muscle cell dysfunction in neurodegeneration

Vascular smooth muscle cells (VSMCs) are the key moderators of cerebrovascular dynamics in response to the brain's oxygen and nutrient demands. Crucially, VSMCs may provide a sensitive biomarker for neurodegenerative pathologies where vasculature is compromised. An increasing body of research suggests that VSMCs have remarkable plasticity and their pathophysiology may play a key role in the complex process of neurodegeneration. Furthermore, extrinsic risk factors, including environmental conditions and traumatic events can impact vascular function through changes in VSMC morphology. VSMC dysfunction can be characterised at the molecular level both preclinically, and clinically ex vivo. However the identification of VSMC dysfunction in living individuals is important to understand changes in vascular function at the onset and progression of neurological disorders such as dementia, Alzheimer's disease, and Parkinson's disease. A promising technique to identify changes in the state of cerebral smooth muscle is cerebrovascular reactivity (CVR) which reflects the intrinsic dynamic response of blood vessels in the brain to vasoactive stimuli in order to modulate regional cerebral blood flow (CBF). In this work, we review the role of VSMCs in the most common neurodegenerative disorders and identify physiological systems that may contribute to VSMC dysfunction. The evidence collected here identifies VSMC dysfunction as a strong candidate for novel therapeutics to combat the development and progression of neurodegeneration, and highlights the need for more research on the role of VSMCs and cerebrovascular dynamics in healthy and diseased states.

Current and future therapeutic perspective in chronic heart failure

The incidence of heart failure is primarily flat or declining for a presumably reflecting better management of cardiovascular diseases, but that of heart failure with preserved ejection fraction (HFpEF) is probably increasing for the lack of an established effective treatment. Moreover, there is no specific pharmacological treatment for patients with heart failure with mildly reduced ejection fraction (HFmrEF) since no substantial prospective randomized clinical trial has been performed exclusively in such population. According to the recent 2021 European Society of Cardiology (ESC) guidelines, the triad composed of an Angiotensin Converting Enzyme inhibitor or Angiotensin Receptor-Neprilysin Inhibitor (ARNI), a beta-blocker, and a Mineralcorticoid Receptor Antagonist is the cornerstone therapy for all patients with heart failure with reduced ejection fraction (HFrEF) but a substantial gap exists for patients with HFpEF/HFmrEF. Despite the important role of the Renin-Angiotensin-Aldosterone System (RAAS) in heart failure pathophysiology, RAAS blockers were found ineffective for HFpEF patients. Indeed, even the new drug class of ARNI was found effective only in HFrEF patients. In this regard, a therapeutic alternative may be represented by drug stimulating the non-classic RAAS (ACE2 and A1-7) as well as other emerging drug classes (such as SGLT2 inhibitors). Reflecting on this global health burden and the gap in treatments among heart failure phenotypes, we summarize the leading players of heart failure pathophysiology, the available pharmacological treatments for each heart failure phenotype, and that in future development.

Protective Effects of Estrogen on Cardiovascular Disease Mediated by Oxidative Stress

Perimenopause is an important stage of female senescence. Epidemiological investigation has shown that the incidence of cardiovascular disease in premenopausal women is lower than that in men, and the incidence of cardiovascular disease in postmenopausal women is significantly higher than that in men. This phenomenon reveals that estrogen has a definite protective effect on the cardiovascular system. In the cardiovascular system, oxidative stress is considered important in the pathogenesis of atherosclerosis, myocardial dysfunction, cardiac hypertrophy, heart failure, and myocardial ischemia. From the perspective of oxidative stress, estrogen plays a regulatory role in the cardiovascular system through the estrogen receptor, providing strategies for the treatment of menopausal women with cardiovascular diseases.

Dual stimuli-responsive nanoplatform based on core-shell structured graphene oxide/mesoporous silica@alginate

A dual stimuli-responsive nanoplatform was rationally designed for controlled drug delivery. The nanosheets of graphene oxide (GO) were first modified with aminated mesoporous silica (NH₂-mSiO₂), and then methotrexate (MTX) was loaded into the mesopores of mSiO₂. Alginate (Alg) acted as the "gatekeeper" was then anchored to the MTX-loaded GO/NH₂-mSiO₂ by amidation reaction, achieving the encapsulation of MTX in the core-shell structured GO/mSiO₂@Alg. Due to the high pH sensitivity of amide bond and the excellent photothermal conversion ability of GO, the constructed nanoplatform could be used for pH and near-infrared (NIR) controlled delivery of MTX. The results of cell viability test demonstrate the high inhibitory rate of the dual stimuli-responsive nanoplatform toward hepatoma (HepG2) cells.

Pharmacodynamic and pharmacokinetic effects of S086, a novel angiotensin receptor neprilysin inhibitor

BACKGROUND AND PURPOSE

Angiotensin receptor-NEP inhibitor (ARNi), which includes an angiotensin receptor blocker (ARB) and a neprilysin inhibitor (NEPi), has been proven safe and effective for treating heart failure with reduced ejection fraction (HF-REF). S086 is a novel single-molecule ARNi that includes the molecular moieties of EXP3174 (the active metabolite of the ARB losartan) and sacubitril (a NEP inhibitor prodrug) in a 1:1 M ratio. We performed preclinical animal model studies to evaluate the efficacy of S086 in treating HF.

EXPERIMENTAL APPROACH

Rat and dog models of myocardial ischemia-induced chronic heart failure were used in this research.

PRINCIPAL RESULTS

The oral administration of S086 dose-dependently lowered the heart weight index, attenuated cardiac fibrosis, and improved left ventricular ejection fraction, shortening fraction, and cardiac output, without effects on hemodynamics in animal models of myocardial ischemia-induced chronic heart failure. A comparable protective effect to LCZ696 was observed for S086 at an equal molar dose in dog models. In addition, S086 was superior to LCZ696 since it significantly reversed the decrease in left ventricular posterior wall end-systolic thickness.

CONCLUSION

This animal study suggests that S086 is effective in treating myocardial ischemia-induced chronic heart failure.

Combinatorial inhibition of Angiotensin converting enzyme, Neutral endopeptidase and Aminopeptidase N by N-methylated peptides alleviates blood pressure and fibrosis in rat model of dexamethasone-induced hypertension

Angiotensin converting enzyme (ACE), neutral endopeptidase (NEP) and aminopeptidase N (APN) are responsible for generation of vasoactive peptides that regulates vasoconstriction, vasodilation and natriuresis, which altogether regulate blood pressure. Cumulative inhibition of ACE, NEP and APN effectively blocks the progression of respective pathways. In this study, N-methylated peptide inhibitors F-N(Me)H-L, V-N(Me)F-R and R-N(Me)V-Y were synthesized against ACE, NEP and APN respectively, using their respective physiological substrates. F-N(Me)H-L inhibited ACE activity with an IC₅₀ of 83 nmol/L, V-N(Me)F-R inhibited NEP activity with an IC₅₀ of 1.173 μmol/L and R-N(Me)V-Y inhibited APN activity with an IC₅₀ of 3.94 nmol/L respectively. Further, the anti-hypertensive effect of N-methylated peptides was evaluated using rat model of dexamethasone-induced hypertension. Individual peptides and their cocktail treatment were started from day 6 of the study period and blood pressure was measured on every alternate day during 15 day study. Administration of F-N(Me)H-L (138 ± 3 mmHg) and cocktail of all the three peptides at a dose of 100 mg/kg significantly reduced systolic blood pressure (SBP) compared to dexamethasone group (SBP of Groups-dexamethasone; (167 ± 5 mmHg), F-N(Me)H-L (138 ± 3 mmHg), and Cocktail (122 ± 3 mmHg). Anti-hypertensive, anti-hypertrophic and anti-fibrotic effects of N-methylated peptides and cocktail was further reflected by the decreased levels of circulating Ang II and increased ANP levels in sera of hypertensive rats along with decrease in collagen deposition in heart and kidney. Though, ACE inhibition is adequate to reduce SBP, targeting NEP and APN along with ACE is beneficial in tackling hypertension and associated fibrosis of heart.

Evolving Use of Biomarkers in the Management of Heart Failure

Objective, noninvasive, clinical assessment of patients with heart failure can be made using biomarker measurements, including natriuretic peptides, cardiac troponins, soluble suppression of tumorigenicity 2, and galectin-3. The aim of this review is to provide clinicians with guidance on the use of heart failure biomarkers in clinical practice. The authors provide a didactic narrative based on current literature, an exemplary case study, and their clinical experience.

Effects of dual angiotensin type 1 receptor/neprilysin inhibition vs. angiotensin type 1 receptor inhibition on target organ injury in the stroke-prone spontaneously hypertensive rat

OBJECTIVES

The combination of AT1 blocker/neutroendopeptidase neprilysin inhibition (ARNi) represents an interesting approach to reduce cardiovascular risk in hypertension. We assessed the efficacy of ARNi, compared with angiotensin II type 1 receptor blockade alone, on blood pressure (BP) and on protection from target organ damage development in the stroke-prone spontaneously hypertensive rat (SHRSP).

METHODS

In high-salt fed SHRSP, we assessed plasma and tissue natriuretic peptides, urinary volume, BP and body weight over a short-term treatment (6 weeks) with either ARNi (sacubitril/valsartan 68 mg/kg per day) or valsartan (30 mg/kg per day), protection from stroke and renal damage (as documented by proteinuria) over 4 months of treatment with either sacubitril/valsartan or valsartan; the ability of either treatment to reduce progression of cerebrovascular and renal damage after 2 weeks of high-salt diet.

RESULTS

Higher levels of plasma and tissue atrial natriuretic peptide, of urinary cyclic guanosine 3'5'monophosphate and urine volumes, along with lower BP levels, were found upon sacubitril/valsartan as compared with valsartan over the short-term treatment. Sacubitril/valsartan caused a significant reduction of both BP and proteinuria levels and complete prevention of stroke over the long-term treatment. Once organ damage was established, a significant delay of its progression was observed with sacubitril/valsartan.

CONCLUSION

The dual angiotensin II type 1 receptor/neutroendopeptidase inhibition significantly increased atrial natriuretic peptide level and reduced BP. Complete prevention of stroke was achieved in this model. The ability of sacubitril/valsartan to reduce organ damage progression was superior to that of valsartan alone. ARNi may represent a highly effective therapeutic agent to protect from target organ damage development in hypertension.

Molecular Implications of Natriuretic Peptides in the Protection from Hypertension and Target Organ Damage Development

The pathogenesis of hypertension, as a multifactorial trait, is complex. High blood pressure levels, in turn, concur with the development of cardiovascular damage. Abnormalities of several neurohormonal mechanisms controlling blood pressure homeostasis and cardiovascular remodeling can contribute to these pathological conditions. The natriuretic peptide (NP) family (including ANP (atrial natriuretic peptide), BNP (brain natriuretic peptide), and CNP (C-type natriuretic peptide)), the NP receptors (NPRA, NPRB, and NPRC), and the related protease convertases (furin, corin, and PCSK6) constitute the NP system and represent relevant protective mechanisms toward the development of hypertension and associated conditions, such as atherosclerosis, stroke, myocardial infarction, heart failure, and renal injury. Initially, several experimental studies performed in different animal models demonstrated a key role of the NP system in the development of hypertension. Importantly, these studies provided relevant insights for a better comprehension of the pathogenesis of hypertension and related cardiovascular phenotypes in humans. Thus, investigation of the role of NPs in hypertension offers an excellent example in translational medicine. In this review article, we will summarize the most compelling evidence regarding the molecular mechanisms underlying the physiological and pathological impact of NPs on blood pressure regulation and on hypertension development. We will also discuss the protective effect of NPs toward the increased susceptibility to hypertensive target organ damage.

Natriuretic peptides in heart failure: Current achievements and future perspectives

The last two centuries have witnessed countless discoveries in the field of medicine that found their roots in the up growing development of technology as well as in the visionary ideas of brilliant scientists and research groups. One of the most important discoveries in the field of cardiovascular medicine allowed to break the paradigm identifying the heart with mere mechanical pump and to characterize its intriguing endocrine properties. Indeed, the discovery of hormones produced by the cardiac chambers, the natriuretic peptides, represents one of the milestones of the current conception of complexity of integrated human physiology. In the last four decades, the role of these hormones in the regulation of the cardiovascular system, in physiology and diseases, has been defined piece after piece. From diagnostic and prognostic markers, natriuretic peptides have become one of the most relevant clinical biomarker and a reliable target for establishing the efficacy of therapies. Recently and successfully, natriuretic peptide-based strategies are proposed as therapeutic weapons to improve outcome in heart failure. The future will witness potential further therapeutic application of natriuretic peptides that are currently being actively investigated.

Sacubitril/valsartan (LCZ696) significantly reduces aldosterone and increases cGMP circulating levels in a canine model of RAAS activation

Simultaneous blockade of angiotensin receptors and enhancement of natriuretic peptides (NP) by the first-in-class angiotensin receptor neprilysin (NEP) inhibitor sacubitril/valsartan constitutes an effective approach to treating heart failure. This study examined the effects of sacubitril/valsartan (225 and 675 mg/day) vs. placebo, sacubitril (360 mg/day), valsartan (900 mg/day), and benazepril (5 mg/day) on the dynamics of the renin-angiotensin-aldosterone system (RAAS) and the NP system in dogs. Beagle dogs (n = 18) were fed a low-salt diet (0.05% Na) for 15 days to model RAAS activation observed in clinical heart failure. Drugs were administered once daily during the last 10 days, while the effects on the RAAS and NPs were assessed on Day 1, 5, and 10. Steady-state pharmacokinetics of the test agents were evaluated on Day 5. Compared with placebo, sacubitril/valsartan (675 mg) substantially increased cGMP circulating levels, while benazepril and valsartan showed no effect. Additionally, sacubitril/valsartan (675 mg) and valsartan significantly increased plasma renin activity, angiotensin I and angiotensin II concentrations. Finally, sacubitril/valsartan (both doses), and valsartan significantly decreased plasma aldosterone vs. placebo. Systemic exposure to valsartan following sacubitril/valsartan 675 mg administration was similar to that observed with valsartan 900 mg administration alone. Sacubitril/valsartan favorably modulates the dynamics of the renin and NP cascades through complementary NEP and RAAS inhibition.

Navigating the Future of Cardiovascular Drug Development-Leveraging Novel Approaches to Drive Innovation and Drug Discovery: Summary of Findings from the Novel Cardiovascular Therapeutics Conference

PURPOSE

The need for novel approaches to cardiovascular drug development served as the impetus to convene an open meeting of experts from the pharmaceutical industry and academia to assess the challenges and develop solutions for drug discovery in cardiovascular disease.

METHODS

The Novel Cardiovascular Therapeutics Summit first reviewed recent examples of ongoing or recently completed programs translating basic science observations to targeted drug development, highlighting successes (protein convertase sutilisin/kexin type 9 [PCSK9] and neprilysin inhibition) and targets still under evaluation (cholesteryl ester transfer protein [CETP] inhibition), with the hope of gleaning key lessons to successful drug development in the current era. Participants then reviewed the use of innovative approaches being explored to facilitate rapid and more cost-efficient evaluations of drug candidates in a short timeframe.

RESULTS

We summarize observations gleaned from this summit and offer insight into future cardiovascular drug development.

CONCLUSIONS

The rapid development in genetic and high-throughput drug evaluation technologies, coupled with new approaches to rapidly evaluate potential cardiovascular therapies with in vitro techniques, offer opportunities to identify new drug targets for cardiovascular disease, study new therapies with better efficiency and higher throughput in the preclinical setting, and more rapidly bring the most promising therapies to human testing. However, there must be a critical interface between industry and academia to guide the future of cardiovascular drug development. The shared interest among academic institutions and pharmaceutical companies in developing promising therapies to address unmet clinical needs for patients with cardiovascular disease underlies and guides innovation and discovery platforms that are significantly altering the landscape of cardiovascular drug development.

Stimulating the Activity of Amyloid-Beta Degrading Enzymes: A Novel Approach for the Therapeutic Manipulation of Amyloid-Beta Levels

Alzheimer's disease is a debilitating neurological disease placing significant burden on health care budgets around the world. It is widely believed that accumulation of amyloid-beta (Aβ) in the brain is a key event that initiates neurodegeneration, thus the clearance of Aβ from brain could be a key therapeutic strategy. Aβ exists in an equilibrium in healthy individuals, and recent research would suggest that dysfunction in the clearance pathways is the driving force behind its accumulation. One mechanism of clearance is proteolytic degradation by enzymes, and increasing the expression of these enzymes in animal models of Alzheimer's disease has indeed shown promising results. This approach could be challenging to translate into the clinic given the likely need for genetic manipulation. We hypothesize that stimulating the activity of these enzymes (as opposed to increasing expression) through pharmacological agents will enhance degradation or at least prevent amyloid deposition, and is therefore another potentially novel avenue to manipulate Aβ levels for therapeutic purposes. We discuss the recent research supporting this hypothesis as well as possible drawbacks to this approach.

Resetting the neurohormonal balance in heart failure (HF): the relevance of the natriuretic peptide (NP) system to the clinical management of patients with HF

The natriuretic peptide (NP) system, which includes atrial natriuretic peptide, B-type natriuretic peptide, and C-type natriuretic peptide, has an important role in cardiovascular homeostasis, promoting a number of physiological effects including diuresis, vasodilation, and inhibition of the renin-angiotensin-aldosterone system. Heart failure (HF) is associated with defects in NP processing and synthesis, and there is a strong relationship between NP levels and disease state. NPs are useful biomarkers in HF, and their use in diagnosis and evaluation of prognosis is well established, particularly in patients with HF with reduced ejection fraction (HFrEF). There has also been interest in their use to guide disease management and therapeutic decision making. An understanding of NPs in HF has also resulted in interest in synthetic NPs for the treatment of HF and in treatments that target neprilysin, a protease that degrades NPs. A novel drug, the angiotensin receptor neprilysin inhibitor sacubitril/valsartan (LCZ696), which simultaneously inhibits neprilysin and blocks the angiotensin II type I receptor, was shown to have a favorable efficacy and safety profile in patients with HFrEF and has been approved for use in such patients in Europe and the USA. In light of the development of treatments that target neprilysin and of recent data in relation to synthetic NPs, it is timely to review the current understanding of the role of NPs in HF and their use in diagnosis, evaluating prognosis and guiding treatment, as well as their place in HF therapy.

Silent disease progression in clinically stable heart failure

Heart failure with reduced ejection fraction (HFrEF) is a progressive disorder whereby cardiac structure and function continue to deteriorate, often despite the absence of clinically apparent signs and symptoms of a worsening disease state. This silent yet progressive nature of HFrEF can contribute to the increased risk of death-even in patients who are 'clinically stable', or who are asymptomatic or only mildly symptomatic-because it often goes undetected and/or undertreated. Current therapies are aimed at improving clinical symptoms, and several agents more directly target the underlying causes of disease; however, new therapies are needed that can more fully address factors responsible for underlying progressive cardiac dysfunction. In this review, mechanisms that drive HFrEF, including ongoing cardiomyocyte loss, mitochondrial abnormalities, impaired calcium cycling, elevated LV wall stress, reactive interstitial fibrosis, and cardiomyocyte hypertrophy, are discussed. Additionally, limitations of current HF therapies are reviewed, with a focus on how these therapies are designed to counteract the deleterious effects of compensatory neurohumoral activation but do not fully prevent disease progression. Finally, new investigational therapies that may improve the underlying molecular, cellular, and structural abnormalities associated with HF progression are reviewed.

Neurohormonal Blockade in Heart Failure

A key feature of chronic heart failure (HF) is the sustained activation of endogenous neurohormonal systems in response to impaired cardiac pumping and/or filling properties. The clinical use of neurohormonal blockers has revolutionised the care of HF patients over the past three decades. Drug therapy that is active against imbalance in both the autonomic and renin-angiotensin-aldosterone systems consistently reduces morbidity and mortality in chronic HF with reduced left ventricular ejection fraction and in sinus rhythm. This article provides an assessment of the major neurohormonal systems and their therapeutic blockade in patients with chronic HF.

Hypertension in Patients with Heart Failure with Reduced Ejection Fraction

Hypertension (HTN) is a well-known health problem associated with considerable morbidity and mortality and it is an important risk factor for the development of heart failure (HF). These findings support the need for optimizing the antihypertensive strategies to prevent the progression to HF. Interestingly, the progression from HTN to HF, among other things, may be a consequence of inappropriate over-activation of the renin-angiotensin-aldosterone system (RAAS), sympathetic nervous system (SNS), and the natriuretic peptide system (NPS). In the present review, we will discuss the pathophysiological aspects of the progression from HTN to HF with reduced ejection fraction (HFrEF) and we will focus on the evolution of different pharmacological therapies which are reported to be effective in reducing BP and improving HF outcomes, paying particular attention to the recent trials that have demonstrated the efficacy of the combined therapy of RAAS blockade and Neprilysin (NEP) inhibitor in lowering BP and mediating several beneficial actions within cardiovascular tissues, such as avoiding the worsening of HF.

New and old roles of the peripheral and brain renin-angiotensin-aldosterone system (RAAS): Focus on cardiovascular and neurological diseases

It is commonly accepted that the renin-angiotensin-aldosterone system (RAAS) is a cardiovascular circulating hormonal system that plays also an important role in the modulation of several patterns in the brain. The pathway of the RAAS can be divided into two classes: the traditional pathway of RAAS, also named classic RAAS, and the non-classic RAAS. Both pathways play a role in both cardiovascular and neurological diseases through a peripheral or central control. In this regard, renewed interest is growing in the last years for the consideration that the brain RAAS could represent a new important therapeutic target to regulate not only the blood pressure via central nervous control, but also neurological diseases. However, the development of compounds able to cross the blood-brain barrier and to act on the brain RAAS is challenging, especially if the metabolic stability and the half-life are taken into consideration. To date, two drug classes (aminopeptidase type A inhibitors and angiotensin IV analogues) acting on the brain RAAS are in development in pre-clinical or clinical stages. In this article, we will present an overview of the biological functions played by peripheral and brain classic and non-classic pathways of the RAAS in several clinical conditions, focusing on the brain RAAS and on the new pharmacological targets of the RAAS.

Effect of Inhibition or Deletion of Neutral Endopeptidase on Neuropathic Endpoints in High Fat Fed/Low Dose Streptozotocin-Treated Mice

Previously we demonstrated that a vasopeptidase inhibitor of angiotensin converting enzyme and neutral endopeptidase (NEP), a protease that degrades vaso- and neuro-active peptides, improves neural function in diabetic rodent models. The purpose of this study was to determine whether inhibition or deletion of NEP provides protection from neuropathy caused by diabetes with an emphasis on morphology of corneal nerves as a primary endpoint. Diabetes, modeling type 2, was induced in C57Bl/6J and NEP deficient mice through a combination of a high fat diet and streptozotocin. To inhibit NEP activity, diabetic C57Bl/6J mice were treated with candoxatril using a prevention or intervention protocol. Twelve weeks after the induction of diabetes in C57Bl/6J mice, the existence of diabetic neuropathy was determined through multiple endpoints including decrease in corneal nerves in the epithelium and sub-epithelium layer. Treatment of diabetic C57Bl/6J mice with candoxatril improved diabetic peripheral neuropathy and protected corneal nerve morphology with the prevention protocol being more efficacious than intervention. Unlike C57Bl/6J, mice deficient in NEP were protected from the development of neuropathologic alterations and loss of corneal nerves upon induction of diabetes. These studies suggest that NEP contributes to the development of diabetic neuropathy and may be a treatable target.

Case study of patents related to captopril, Squibb's first blockbuster

INTRODUCTION

Arterial hypertension affects over one billion people around the world, making the prevention and treatment of this disease vital. Despite the efforts made to develop new antihypertensive drugs, few new therapies have become available. Angiotensin-converting enzyme (ACE) inhibitors have heralded major steps forward in the treatment of arterial hypertension and cardiovascular diseases since the first compound of this class, captopril, was approved for clinical use in 1981. Areas covered: In this review, the authors investigated the patent documents that cite the priority patent for captopril, Squibb's first blockbuster, or any other patent from its patent family. The documents were classified into the following: new compounds, new compositions, treatment, process (preparation of a compound), use of a compound, and process for the preparation of an intermediate. Therefore, the readers can identify potential innovations in the field. Expert opinion: The pharmaceutical sector has attempted to provide significant technological developments on anti-hypertensive drugs based on the patenting of captopril, including the development of new compositions further comprising an ACE inhibitor and other antihypertensive agent, along with dual action compounds, novel molecules with dual activity. The target is to find a new agent with better blood pressure-lowering efficacy, improved safety and good tolerability profile.

Pharmacology of heart failure: From basic science to novel therapies

Chronic heart failure is one of the leading causes for hospitalization in the United States and Europe, and is accompanied by high mortality. Current pharmacological therapy of chronic heart failure with reduced ejection fraction is largely based on compounds that inhibit the detrimental action of the adrenergic and the renin-angiotensin-aldosterone systems on the heart. More than one decade after spironolactone, two novel therapeutic principles have been added to the very recently released guidelines on heart failure therapy: the HCN-channel inhibitor ivabradine and the combined angiotensin and neprilysin inhibitor valsartan/sacubitril. New compounds that are in phase II or III clinical evaluation include novel non-steroidal mineralocorticoid receptor antagonists, guanylate cyclase activators or myosine activators. A variety of novel candidate targets have been identified and the availability of gene transfer has just begun to accelerate translation from basic science to clinical application. This review provides an overview of current pharmacology and pharmacotherapy in chronic heart failure at three stages: the updated clinical guidelines of the American Heart Association and the European Society of Cardiology, new drugs which are in clinical development, and finally innovative drug targets and their mechanisms in heart failure which are emerging from preclinical studies will be discussed.

Endostatin and irradiation modifies the activity of ADAM10 and neprilysin in breast cancer cells

Angiogenesis, the formation of new blood vessels, is regarded as a key cancer cell property. Endostatin (ES) is a potential antiangiogenic agent and it may be useful when implemented in combination with other cancer therapeutic strategies. The present study investigated the in vitro effects of ES, radiotherapy (RT) or combination therapy (ES + RT) on two important proteases, a disintegrin and metalloproteinase domain‑containing protein 10 (ADAM10) and neprilysin (NEP) in 4T1 mouse breast cancer cells and the more metastatic phenotype of 4THMpc breast cancer cells. 4T1 and 4THMpc cells were treated with recombinant murine ES (4 µg/ml) alone, RT (45 Gy) alone or with ES + RT. ADAM10 enzyme activity was determined using a tumor necrosis factor‑α converting enzyme (α‑secretase) activity assay kit, and NEP enzyme activity was measured with a fluorometric assay based on the generation of free dansyl‑D‑Ala‑Gly from N-dansyl-Ala-Gly-D-nitro-Phe-Gly, the substrate of NEP. Western blotting analysis was performed to determine whether the altered enzyme activity levels of the two cell lines occurred due to changes in expression level. These data indicate that ES independently potentiates the activity of ADAM10 and NEP enzymes in 4T1 and 4THMpc breast cancer cells.

Pharmacologic management of angioedema induced by angiotensin-converting enzyme inhibitors

Purpose

The published evidence on pharmacologic approaches to the management of angiotensin-converting enzyme inhibitor (ACEI)–induced angioedema is reviewed.

Summary

Angioedema is a serious, potentially life-threatening adverse effect of ACEI use. Although the underlying mechanism is not fully understood, excess bradykinin produced through a complex interplay between the kallikrein-kinin and renin-angiotensin-aldosterone systems is thought to play a major role. The nonallergic nature of the reaction renders traditional therapies (corticosteroids and antihistamines) ineffective because those agents do not modify the proposed pathophysiology. Fresh frozen plasma (FFP) provides kinase II, a protein that breaks down bradykinin. Case reports support FFP as a treatment for ACEI-induced angioedema, but no formal evaluations have been completed to date. Both ecallantide and complement 1 esterase (C1) inhibitor concentrate reduce bradykinin production through upstream inhibition of kallikrein. C1 inhibitor concentrate has been used successfully to manage ACEI-induced angioedema in a few reported cases, but robust supportive studies are lacking. Conversely, ecallantide has been evaluated in multiple randomized trials but has not been shown to offer advantages over traditional therapies. The use of icatibant, a direct antagonist of bradykinin B2 receptors, was reported to be beneficial in several case reports and in a small Phase II study, safely and rapidly reducing symptoms of ACEI-induced angioedema. An ongoing Phase III trial (NCT01919801) will better define the role of icatibant in the management of ACEI-induced angioedema.

Conclusion

FFP, C1 inhibitor, and icatibant appear to be safe and effective therapeutic options for the management of ACEI-induced angioedema, whereas it appears ecallantide should be avoided.

Blood-Based Biomarkers for Metabolic Syndrome

Metabolic syndrome (MetS) is a constellation of factors increasing the risk of type 2 diabetes mellitus (T2DM), cardiovascular disease (CVD), and cancer. MetS diagnosis is cumbersome and the precise diagnosis differs throughout the world. Efforts are underway to find MetS biomarkers that could all be analysed in a single blood sample. Here we review recent advances, including progress on circulating exosomes and microvesicles and their molecular contents, as well as DNA, RNAs, and proteins taken directly from blood samples. While additional research is now warranted to advance upon these findings, there is reason for optimising that such blood-based entities will be beneficial for MetS diagnosis and will help reduce risk of T2DM, CVD, and cancers, contributing both societal and economic benefit.

Modulation of RAAS-natriuretic peptides in the treatment of HF: Old guys and newcomers

The use of renin-angiotensin-aldosterone system (RAAS) inhibitors in the treatment of chronic heart failure (HF) and arterial hypertension is recommended by the European Society of Cardiology Guidelines on the basis of consolidated evidence supporting their efficacy in the development of such a disease. However, the high incidence of re-hospitalization and mortality in patients undergoing chronic HF, leads to the need for the development of novel RAAS inhibitors possessing a better pharmacokinetic/pharmacodynamics profile in approaching hemodynamic imbalance and myocardial dysfunction associated with the development of chronic HF. Here we summarize some of the recent advances in the area of RAAS-modulators, including novel renin inhibitors, mineralcorticoid receptor antagonists and novel AT1 and AT2-receptor modulators. In addition, the pharmacology of a new class of compounds which display both AT1-receptor blocking properties combined with inhibition of neprilysin, the vasopeptidase enzyme degradating natriuretic peptide (ARNi), will be reviewed, alongside with their impact in the pathophysiology of chronic HF.

The pathophysiological role of natriuretic peptide-RAAS cross talk in heart failure

Chronic Heart Failure (HF) is still a disease state characterized by elevated morbidity and mortality and represents an unresolved problem for its socio-economic impact. Besides many of the pathophysiological events leading to advanced HF have been widely disclosed in the past decades, the role of neuro-hormonal dysregulation accompanying HF has to be clearly assessed with the objective of better therapeutic approaches in treating such a disease. In the present review article, alongside with a brief re-evaluation of general aspects of HF physiopathology, we summarize recent advances in the cross talk between renin-angiotensin-aldosterone system (RAAS) with natriuretic peptides (NPs) which have been shown to play a relevant role in the development of severe HF. The role of RAAS-NPs interplay has been shown to be crucial in both hemodynamic and tissue remodeling associated to cardiomyocyte dysfunction, leading to advanced impairment of left ventricular performance. On the basis of these results, the development of drugs resetting both RAAS and NPs system seems to be promising for a successful long term treatment of chronic HF.

Angioedema induced by cardiovascular drugs: new players join old friends

During the last years, two new cardiovascular drug classes, namely inhibitors of DPP IV or neprilysin, have been developed. In both cases, there is clinical evidence for their potential to induce angioedema as known already from blockers of the renin-angiotensin-aldosterone system (RAAS). The majority of angioedema induced by DPP IV inhibitors occurs during concomitant treatment with ACEi and is therefore likely mediated by overactivation of bradykinin type 2 receptors (B2). In striking contrast, the molecular pathways causing angioedema induced by neprilysin inhibitors, that is, sacubitril, are unclear, although a contribution of bradykinin appears likely. Nevertheless, there is no clinical evidence suggesting that inhibition of B2 might relieve the symptoms and/or prevent invasive treatment including coniotomy or tracheotomy in angioedema caused by these drugs. Therefore, the risk of angioedema should always be considered, especially in ambulatory care situations where patients have no rapid access to intensive care.

New medical therapies for heart failure

Heart failure (HF) can rightfully be called the epidemic of the 21(st) century. Historically, the only available medical treatment options for HF have been diuretics and digoxin, but the capacity of these agents to alter outcomes has been brought into question by the scrutiny of modern clinical trials. In the past 4 decades, neurohormonal blockers have been introduced into clinical practice, leading to marked reductions in morbidity and mortality in chronic HF with reduced left ventricular ejection fraction (LVEF). Despite these major advances in pharmacotherapy, our understanding of the underlying disease mechanisms of HF from epidemiological, clinical, pathophysiological, molecular, and genetic standpoints remains incomplete. This knowledge gap is particularly evident with respect to acute decompensated HF and HF with normal (preserved) LVEF. For these clinical phenotypes, no drug has been shown to reduce long-term clinical event rates substantially. Ongoing developments in the pharmacotherapy of HF are likely to challenge our current best-practice algorithms. Novel agents for HF therapy include dual-acting neurohormonal modulators, contractility-enhancing agents, vasoactive and anti-inflammatory peptides, and myocardial protectants. These novel compounds have the potential to enhance our armamentarium of HF therapeutics.

Role of the Renin-Angiotensin-Aldosterone System and Its Pharmacological Inhibitors in Cardiovascular Diseases: Complex and Critical Issues

Hypertension is one of the major risk factor able to promote development and progression of several cardiovascular diseases, including left ventricular hypertrophy and dysfunction, myocardial infarction, stroke, and congestive heart failure. Also, it is one of the major driven of high cardiovascular risk profile in patients with metabolic complications, including obesity, metabolic syndrome and diabetes, as well as in those with renal disease. Thus, effective control of hypertension is a key factor for any preventing strategy aimed at reducing the burden of hypertension-related cardiovascular diseases in the clinical practice. Among various regulatory and contra-regulatory systems involved in the pathogenesis of cardiovascular and renal diseases, renin-angiotensin system (RAS) plays a major role. However, despite the identification of renin and the availability of various assays for measuring its plasma activity, the specific pathophysiological role of RAS has not yet fully characterized. In the last years, however, several notions on the RAS have been improved by the results of large, randomized clinical trials, performed in different clinical settings and in different populations treated with RAS inhibiting drugs, including angiotensin converting enzyme (ACE) inhibitors and antagonists of the AT1 receptor for angiotensin II (ARBs). These findings suggest that the RAS should be considered to have a central role in the pathogenesis of different cardiovascular diseases, for both therapeutic and preventive purposes, without having to measure its level of activation in each patient. The present document will discuss the most critical issues of the pathogenesis of different cardiovascular diseases with a specific focus on RAS blocking agents, including ACE inhibitors and ARBs, in the light of the most recent evidence supporting the use of these drugs in the clinical management of hypertension and hypertension-related cardiovascular diseases.

Small molecule and peptide therapies for chronic heart failure: a patent review (2011 - 2014)

INTRODUCTION

Chronic heart failure (CHF) is the long-term inability of the heart to meet circulatory demands under normal conditions. Effects of CHF can include increased blood volume, increased vascular resistance and compromised contractility leading to fluid retention, dyspnea and fatigue. Current standard of care for chronic systolic heart failure is directed towards managing hypoperfusion through the renin-angiotensin-aldosterone and sympathetic nervous systems. Treatment may also involve reversal of maladaptive cardiac remodeling and prevention of life-threatening arrhythmias.

AREAS COVERED

This review highlights small molecule and peptidic agents for the treatment of CHF with patents published between 2011 and 2014. Targets are subdivided into inotropic agents, ventricular remodeling, diuretics and the renin-angiotensin-aldosterone system.

EXPERT OPINION

CHF represents a large, unmet medical need where improved therapies are needed. The renin-angiotensin-aldosterone system pathway continues to be a major source of new therapies for CHF with new inotropic therapies emerging. Promising initial clinical results for a few approaches combined with the expectation of additional clinical results in the near future make this an exciting time in the pursuit of new treatments for CHF.

LCZ696 : a new paradigm for the treatment of heart failure?

INTRODUCTION

Heart failure (HF) represents a significant healthcare issue because of its ever-increasing prevalence, poor prognosis and complex pathophysiology. Currently, blockade of the renin-angiotensin-aldosterone system (RAAS) is the cornerstone of treatment; however, the combination of RAAS blockade with inhibition of neprilysin (NEP), an enzyme that degrades natriuretic peptides, has recently emerged as a potentially superior treatment strategy.

AREAS COVERED

Following the results of the recent Phase III Prospective Comparison of ARNI with ACEI to Determine Impact on Global Mortality and Morbidity in Heart Failure clinical trial in patients with chronic HF with reduced ejection fraction (HF-REF), this review focuses on LCZ696 , a first-in-class angiotensin receptor NEP inhibitor. This drug consists of a supramolecular complex containing the angiotensin receptor inhibitor valsartan in combination with the NEP inhibitor prodrug, AHU377. Following oral administration, the LCZ696 complex dissociates and the NEP inhibitor component is metabolized to the active form (LBQ657). Aspects of the trial that might be relevant to clinical practice are also discussed.

EXPERT OPINION

Speculation that LCZ696 will pass the scrutiny of regulatory agencies for HF-REF appears to be justified, and it is likely to become a core therapeutic component in the near future. Replication of the eligibility criteria and titration protocol used in the PARADIGM-HF trial would be valuable in clinical practice and may minimize the risk of adverse events. Although long-term data remain to be generated, the promising results regarding hypertension are likely to expedite acceptance of the drug for HF-REF.

Update on the role of angiotensin in the pathophysiology of coronary atherothrombosis

BACKGROUND

Coronary atherothrombosis due to atherosclerotic plaque rupture or erosion is frequently associated with acute coronary syndromes (ACS). Significant efforts have been made to elucidate the pathophysiological mechanisms underlying acute coronary events.

MATERIALS AND METHODS

This narrative review is based on the material searched for and obtained via PubMed up to August 2014. The search terms we used were as follows: 'angiotensin, acute coronary syndromes, acute myocardial infarction' in combination with 'atherosclerosis, vulnerability, clinical trial, ACE inhibitors, inflammation'.

RESULTS

Among several regulatory components, the renin-angiotensin system (RAS) was shown as a key pathway modulating coronary atherosclerotic plaque vulnerability. Indeed, these molecules are involved in all stages of atherogenesis. Classically, the RAS is composed by a series of enzymatic reactions leading to the angiotensin (Ang) II generation and activity. However, the knowledge of RAS has expanded and become more complex. The discovery of novel components and their functions has revealed additional pathways that contribute to or counterbalance the actions of Ang II. In this review, we discussed on recent findings concerning the role of different angiotensin peptides in the pathophysiology of ACS and coronary atherothrombosis, exploring the link between these molecules and atherosclerotic plaque vulnerability.

CONCLUSIONS

Treatments selectively targeting angiotensins (including Mas and AT2 agonists, ACE2 recombinant, or Ang-(1-7) and almandine in oral formulations) have been tested in animal studies or in small human subgroups, expanding the perspective in the ACS prevention. These novel strategies, especially in the counter-regulatory axis ACE2/Ang-(1-7)/Mas, might be promising to reduce plaque vulnerability and inflammation.

Angiotensin Receptor Neprilysin Inhibitor LCZ696 Attenuates Cardiac Remodeling and Dysfunction After Myocardial Infarction by Reducing Cardiac Fibrosis and Hypertrophy

Background—

Angiotensin receptor neprilysin inhibitors (ARNi), beyond blocking angiotensin II signaling, augment natriuretic peptides by inhibiting their breakdown by neprilysin. The myocardial effects of ARNi have been little studied until recently. We hypothesized that LCZ696 attenuates left ventricular (LV) remodeling after experimental myocardial infarction (MI), and that this may be contributed to by inhibition of hypertrophy and fibrosis in cardiac cells.

Methods and Results—

One week after MI, adult male Sprague–Dawley rats were randomized to treatment for 4 weeks with LCZ696 (68 mg/kg body weight perorally; MI-ARNi, n=11) or vehicle (MI-vehicle, n=6). Five weeks after MI, MI-ARNi versus MI-vehicle demonstrated lower LV end-diastolic diameter (by echocardiography; 9.7±0.2 versus 10.5±0.3 mm), higher LV ejection fraction (60±2 versus 47±5%), diastolic wall strain (0.23±0.02 versus 0.13±0.02), and circular strain (−9.8±0.5 versus −7.3±0.5%; all P <0.05). LV pressure–volume loops confirmed improved LV function. Despite similar infarct size, MI-ARNi versus MI-vehicle had lower cardiac weights ( P <0.01) and markedly reduced fibrosis in peri-infarct and remote myocardium. Angiotensin II–stimulated incorporation of 3[H]leucine in cardiac myocytes and 3[H]proline in cardiac fibroblast was used to evaluate hypertrophy and fibrosis, respectively. The neprilysin inhibitor component of LCZ696, LBQ657, inhibited hypertrophy but not fibrosis. The angiotensin receptor blocker component of LCZ696, valsartan inhibited both hypertrophy and fibrosis. Dual valsartan+LBQ augmented the inhibitory effects of valsartan and the highest doses completely abrogated angiotensin II–mediated effects.

Conclusions—

LCZ696 attenuated cardiac remodeling and dysfunction after MI. This may be contributed to by superior inhibition of LCZ696 on cardiac fibrosis and cardiac hypertrophy than either stand-alone neprilysin inhibitor or angiotensin receptor blocker.