Adrenomedullin (ADM) in the human forearm vascular bed: effect of neutral endopeptidase inhibition and comparison with proadrenomedullin NH2-terminal 20 peptide (PAMP)

Angiotensin Receptor-Neprilysin Inhibitor Suppresses Renin-Angiotensin-Aldosterone System Activation After Cardiac Surgery Using Cardiopulmonary Bypass

BACKGROUND

Sacubitril/valsartan, being both a neprilysin inhibitor and angiotensin receptor blocker, exhibits a renin-angiotensin-aldosterone system (RAAS) inhibitory effect. However, no study has investigated the administration of sacubitril/valsartan in patients early after surgery using cardiopulmonary bypass.

METHODS AND RESULTS

This was a prospective observational study of 63 patients who underwent open heart surgery and were treated with sacubitril/valsartan. No serious adverse events occurred. Among the 63 patients, sacubitril/valsartan was discontinued in 13 due to hypotension (n=10), renal dysfunction (n=2), and dizziness (n=1). Atrial natriuretic peptide concentrations increased significantly from Day 3 of treatment (P=0.0142 vs. Postoperative Day 1) and remained high thereafter. In contrast, plasma renin activity was significantly suppressed from Day 3 onwards (P=0.00206 vs. Postoperative Day 1). A decrease in creatinine concentrations and an increase in the estimated glomerular filtration rate were observed on Day 3; this improvement in renal function was not observed in the historical control group, in which patients did not receive sacubitril/valsartan. New postoperative atrial fibrillation was less frequent in the study group compared with the historical control (12.7% vs. 38.0%; P=0.0034).

CONCLUSIONS

Sacubitril/valsartan administration was safe immediately after open heart surgery in patients without postoperative hypotension. It enhanced serum atrial natriuretic peptide concentrations and suppressed RAAS activation.

Impact of Sacubitril/ Valsartan on quality of life and ejection fraction of heart failure patients with and without chronic kidney disease

Objective

Chronic kidney disease (CKD) patients are at high risk of heart failure (HF) and both share similar risk factors, including diabetes and elevated blood Pressure (B.P). Aim of this study was to determine the impact of sacubitril/valsartan on the quality of life (QOL) and ejection fraction (EF) of patients with HF with and without CKD.

Methods

Single center (Doctors Hospital Lahore), observational study with longitudinal follow up, on 104 HF patients from July 2019 to July 2020. HF was diagnosed on both clinical and echo parameters. New York Heart Association Class II-IV, EF less than or equal to 40% HF with reduced EF and stage three CKD patients were included. Sacubitril/Valsartan was prescribed at a starting daily dose of 50mg and then up titrated to 400mg. Patients were followed up with clinical evaluation, QOL assessment, echocardiography and biochemical profile at one, four, eight and 12 months.

Results

Gender, age, and diabetes mellitus between CKD and non-CKD patients were noted to be statistically different, defined as p<0.05. CKD patients' QOL increased from 45.15 to 57.57 from baseline to 12 months (p-value<0.01). Non-CKD patients' QOL increased from 48.07 to 56.25. In CKD patients, EF increased from 27.87% to 29.29% from baseline to 12 months (p-value 0.03) whereas in non-CKD patients EF improved from 29.42% to 31.43%.

Conclusion

Sacubitril/ valsartan improves QOL in patients of HF with reduced EF both with and without CKD. Clinical improvement was independent of Left Ventricular EF as measured by QOL. Thus, QOL is a useful tool to assess the drug's beneficial effect.

Incidence of hyperkalemia in anuric hemodialysis patients treated with sacubitril/valsartan

INTRODUCTION

Sacubitril/valsartan is increasingly used in hemodialysis patients due to its cardioprotective benefits. However, its impact on serum potassium levels in anuric patients undergoing hemodialysis remains controversial.

METHODS

We conducted a retrospective data from patients undergoing hemodialysis at two dialysis centers. A total of 71 out of 332 patients receiving hemodialysis treatment were enrolled. Mean serum potassium (mean value of 6-8 determinations), peak serum potassium (maximum K value observed during follow-up observations), and other biochemical parameters were recorded at baseline and during the follow-up period.

FINDINGS

After 6 months of follow-up, mean serum potassium increased from 4.84 ± 0.45 mmol/L at baseline to 5.07 ± 0.46 mmol/L at 3 months and 5.04 ± 0.46 mmol/L at 6 months (p < 0.001). Notably, no significant group differences were found in peak serum potassium concentrations between baseline and 6 months after sacubitril/valsartan therapy (5.69 ± 0.56 vs. 5.75 ± 0.41, p = 0.419). Prior to starting sacubitril/valsartan treatment, none of the patients had severe hyperkalemia; however, after 3 and 6 months of sacubitril/valsartan therapy, two (2.80%) and three (4.20%) patients experienced severe hyperkalemia, respectively; however, this difference was not statistically significant. Additionally, there was a significant reduction in blood pressure; however, serum sodium, bicarbonate, and Kt/V values did not change significantly during either period.

DISCUSSION

Sacubitril/valsartan therapy is associated with an increase in serum potassium levels in anuric hemodialysis patients. Nevertheless, the proportion of patients with severe hyperkalemia did not increase significantly. This suggests that the use of sacubitril/valsartan in anuric patients on hemodialysis is relatively safe.

Sacubitril/valsartan reduces proteasome activation and cardiomyocyte area in an experimental mouse model of hypertrophy

Sacubitril/valsartan (Sac/Val) belongs to the group of angiotensin receptor-neprilysin inhibitors and has been used for the treatment of heart failure (HF) for several years. The mechanisms that mediate the beneficial effects of Sac/Val are not yet fully understood. In this study we investigated whether Sac/Val influences the two proteolytic systems, the ubiquitin-proteasome system (UPS) and the autophagy-lysosomal pathway (ALP), in a mouse model of pressure overload induced by transverse aortic constriction (TAC) and in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) treated with endothelin-1 (ET1) serving as a human cellular model of hypertrophy. TAC mice showed a continuous decline in cardiac function starting from day 14 after surgery. Administration of Sac/Val for 6 weeks counteracted the deterioration of cardiac function and attenuated hypertrophy and fibrosis in TAC mice. The expression of ALP key markers did not differ between the groups. Proteasome activity was higher in TAC mice and normalized by Sac/Val. In hiPSC-CMs, all treatments (Sac, Val or Sac/Val) normalized mean cell area. However, Sac alone or in combination with Val, but not Val alone prevented ET1-induced hypertrophic gene program and proteomic changes. In conclusion, Sac/Val normalized proteasome activity, improved cardiac function and reduced fibrosis and hypertrophy in TAC mice. Molecular analysis in hiPSC-CMs suggests that a major part of the beneficial effects of Sac/Val is derived from the Sac action rather than from Val.

Effect of angiotensin receptor-neprilysin inhibitor treatment on erectile dysfunction in heart failure with a reduced ejection fraction

Objective: Erectile dysfunction (ED) is a common condition in patients with heart failure (HF), which impairs quality of life. Our study aimed to compare those patients, who received traditional treatment with a diagnosis of HF and those who received angiotensin receptor-neprilysin inhibitor (ARNI) treatment in addition to the current treatment, in terms of ED at the end of 6 months. Patients and Methods: The study was planned as a single-center, prospective study. The study included 200 patients with heart failure. The patients’ demographic, clinical, and echocardiographic characteristics were recorded, and an international ED scoring questionnaire was applied. The participants in the study were divided into two groups: those who received ARNI treatment and those who did not. After 6 months, the ED questionnaire was applied to the patients again and the groups were compared. Results: The median age of the patients was 53 (years). The median ejection fraction (EF) value was calculated to be 30% and no significant difference was found between the groups (p: 0.122). It was found that N-terminal pro-brain natriuretic peptide (NT-pro- BNP) levels measured at the end of the 6th month were significantly lower in patients who had received ARNI treatment than in those who had not (respectively, 245 pg/ml, 200 pg/ml; p: 0.003). In the analysis performed to detect the presence of ED, it was discovered that the ED score change was significantly higher in the group that had received 6 months of ARNI treatment (p: 0.031) compared to that in the group that had not (p: 0.031). When the ED sub-parameters were compared in terms of the 6-month change rate, it was found that the ARNI group had a significant increase in terms of ED and sexual satisfaction scores, but no significant difference was found in the other parameters (p: 0.001, p: 0.029). Conclusion: Erectile dysfunction is more common in patients with heart failure compared to the rest of society and impairs quality of life. In our study, it was determined that ED complaints decreased significantly in HF patients, who had received ARNI treatment for 6 months than in patients who had not.

Atrial fibrillation in heart failure patients: An update on renin-angiotensin-aldosterone system pathway blockade as a therapeutic and prevention target

Heart failure (HF) and atrial fibrillation (AF) are two cardiovascular (CV) entities that affect millions of individuals worldwide and their prevalence is translated into a significant impact on health care systems. The common pathophysiological pathways that these two share have created an important clinical interrelation, as the coexistence of HF and AF is associated with worse prognosis and treatment challenges. Renin-angiotensin-aldosterone system (RAAS), a critical mechanism in blood pressure (BP) control, was proved to be involved in the pathogenesis of both conditions contributing to their further coexistence. Successful control of BP is of great importance to the management of HF, crucial for the prevention of arrhythmiogenic substrates, while RAAS antagonists may possibly affect the development of new-onset AF as well. There are numerous studies that evaluated the effectiveness of RAAS blockade in AF/HF population and despite comparable or modest results, there is a well-established suggestion that RAAS blockers may contribute to a reduction of HF, CV events and recurrence of AF, along with their potential effective role in the new-onset AF prophylaxis. Angiotensin receptor blockers, according to the evidence, are more effective in that direction, followed by angiotensin converting enzyme inhibitors, whereas the data on aldosterone antagonists are not encouraging, yet do have the potential of significant CV disease modificators regardless of their effects on BP.

Impact of angiotensin receptor-neprilysin inhibition on vascular function in heart failure with reduced ejection fraction: A pilot study

The mechanisms for the benefits of Angiotensin Receptor Neprilysin Inhibition (ARNi) in heart failure patients with reduced ejection fraction (HFrEF) are likely beyond blood pressure reduction. Measures of vascular function such as arterial stiffness and endothelial function are strong prognostic markers of cardiovascular outcomes in HFrEF, yet the impact of ARNi on vascular health remains to be explored. We hypothesized that arterial stiffness and endothelial function would improve after 12 weeks of ARNi in HFrEF. We tested 10 stable HFrEF patients at baseline and following 12 weeks of ARNi [64 ± 9 years, Men/Women: 9/1, left ventricular ejection fraction (EF): 28 ± 6%] as well as 10 stable HFrEF patients that remained on conventional treatment (CON: 60 ± 7 years, Men/Women: 6/4, EF: 31 ± 5%; all p = NS). Arterial stiffness was assessed via carotid-femoral pulse wave velocity (PWV) and endothelial function was assessed via brachial artery flow-mediated dilation (FMD). PWV decreased after 12 weeks of ARNi (9.0 ± 2.1 vs. 7.1 ± 1.2 m/s; p < 0.01) but not in CON (7.0 ± 2.4 vs. 7.5 ± 2.3 m/s; p = 0.35), an effect that remained when controlling for reductions in mean arterial pressure (p < 0.01). FMD increased after 12 weeks of ARNi (2.2 ± 1.9 vs. 5.5 ± 2.1%; p < 0.001) but not in CON (4.8 ± 3.8 vs. 5.4 ± 3.4%; p = 0.34). Baseline PWV (p = 0.06) and FMD (p = 0.07) were not different between groups. These preliminary data suggest that 12 weeks of ARNi therapy may reduce arterial stiffness and improve endothelial function in HFrEF. Thus, the findings from this pilot study suggest that the benefits of ARNi are beyond blood pressure reduction and include improvements in vascular function.

Effects of sacubitril/valsartan on both metabolic parameters and insulin resistance in prediabetic non-obese patients with heart failure and reduced ejection fraction

BACKGROUND

The effects of sacubitril/valsartan (sac/val) on metabolic parameters and insulin resistance (IR) in non-obese/prediabetic patients have not been previously described.

AIM

To evaluate the effects of sac/val on glycemic and metabolic parameters, Homeostatic Model Assessment of IR (HOMA-IR), and echocardiographic parameters in prediabetic patients with heart failure with reduced ejection fraction (HFrEF).

METHODS

Fifty-nine patients with HFrEF (EF < 35%) but without obesity and/or type 2 diabetes mellitus have been enrolled. All the patients at baseline and week 24 underwent complete anthropometrical evaluation and were subjected to an echocardiogram test. IR has been assessed by HOMA-IR.

RESULTS

After 24-week of treatment with sac/val, a significant reduction in fasting plasma glucose (109 ± 9 vs 103 ± 8 mg/dl, p < 0.0001), fasting plasma insulin (16 ± 4 vs 10 ± 4 UI/L), and hemoglobin A1c (HbA1c) value (6% ± 0.5% vs 5.3% ± 0.3%, p < 0.0001) was observed. Similarly, we observed a significant improvement in IR (HOMA-IR, 4.4 ± 0.9 vs 2.5 ± 0.6, p < 0.0001). The echocardiogram evaluation showed a significant reduction of the left ventricular end-diastolic volume (168 ± 24 vs 158 ± 22 ml, p < 0.05), a significant reduction of the left ventricular end-systolic volume (111 ± 26 vs 98 ± 22 ml, p < 0.005), and a significant reduction of E/e' ratio. Sac/val use was also associated with an average 5.1% increase in ejection fraction.

CONCLUSIONS

Our data seem to indicate that sal/val enhances metabolic control and improves insulin resistance also in prediabetic non-obese patients with HFrEF.

Comparison of Sacubitril/Valsartan Versus Enalapril in the Management of Heart Failure

Background and objective

The recent emergence of new molecules like angiotensin receptor-neprilysin inhibitor (ARNI) has highlighted the need for an update in heart failure (HF) management, as they have proven to yield better patient outcomes compared to the traditional angiotensin-converting enzyme inhibitor/angiotensin II receptor blocker (ACEI/ARB) use. This study aimed to compare HF-related hospitalization and death in patients on either ACEI/ARBs or ARNI in a local setting.

Methods

This two-arm interventional study was conducted in the cardiology and internal medicine units of a tertiary care hospital in Pakistan from July 2018 to December 2020. After enrollment, participants were randomized into two groups as per 1:1 ratio using an online research randomizer software (https://www.randomizer.org). Group A received 24/26 or 49/51 mg sacubitril/valsartan twice daily for HF. Group B received 2.5 or 5 mg enalapril twice daily. Patients were followed up for 12 months or till the development of an event.

Results

The sacubitril/valsartan group had significantly fewer HF-related hospitalizations compared to the enalapril group (13.8% vs. 22.4%; p-value: 0.03), with a relative risk reduction (RRR) of 38.3%. The sacubitril/valsartan group had 52% RRR for HF-related deaths compared to the enalapril group.

Conclusion

Based on our findings, treatment with sacubitril/valsartan was superior to enalapril in reducing the risk of hospitalization and death related to HF. The magnitude of the beneficial effects of sacubitril/valsartan as compared to enalapril on cardiovascular mortality was at least as high as that of long-term treatment with enalapril.

Updates in pharmacotherapy of heart failure with reduced ejection fraction

Heart failure is a common entity encountered in healthcare with a vast socioeconomic impact. Recent advances in pharmacotherapy have led to the development of novel therapies with mortality benefits, improvement in heart failure symptoms and hospitalizations. This article is intended to explore those newer pharmacotherapies and summarize the evidence behind guideline directed medical therapy (GDMT) for heart failure with reduced ejection fraction (HFrEF). It has been several years since any significant advances in pharmacotherapy of heart failure have resulted in survival benefit. Angiotensin-neprilysin inhibitors through the PARADIGM-HF and PIONEER-HF trials have shown mortality benefits and a reduction in heart failure hospitalizations and are considered landmark trials in heart failure. Vericiguat is an oral guanylate cyclase stimulator that through the recent VICTORIA trial showed a 10% relative difference in death from cardiovascular cause or hospitalization for heart failure. The sodium-glucose transport protein 2 (SGLT2) inhibitors are another class of medications that have shown promise in the treatment of patients with HFrEF and diabetes mellitus. The CANVAS and EMPA-REG OUTCOME trials showed the potential benefit of SGLT2 inhibitors on cardiovascular mortality, DECLARE-TIMI 58 trial showed that treatment with dapagliflozin reduced the risk of cardiovascular death or hospitalization for heart failure to a greater extent in patients with reduced ejection fraction (EF). Although novel pharmacotherapy is the current focus of intense research, there have been numerous studies on potential benefit of iron supplementation in ferropenic patients with heart failure. Another rapidly expanding area of research in the realm of heart failure is precision medicine and its impact on the development, progression, and treatment of heart failure. The field of heart failure is dynamic and with the influx of data from recent and ongoing trials, newer therapies with morbidity and mortality benefits in HFrEF are now available, nonetheless, much work is still needed.

Effect of laparoscopic sleeve gastrectomy on vasoactive mediators in obese hypertensive patients: A prospective study

INTRODUCTION

The causal relationship between obesity and high blood pressure is established; however, the detailed pathways for such association are still under research. This work aims to assess the changes in neprilysin, vasoconstrictor and vasodilatory molecules in obese hypertensive patients undergoing laparoscopic sleeve gastrectomy (LSG).

PATIENTS

The present prospective study was done on 59 hypertensive obese patients in whom LGS was performed. Blood pressure, as well as blood samples for neprilysin, angiotensinogen, angiotensin II, renin, endothelin-1 "ET-1", aldosterone, atrial natriuretic peptide "ANP" and B-type natriuretic peptide "BNP", were assessed before and 15 months after surgery. Patients were divided into two groups according to the remission of hypertension (HTN).

RESULTS

After 15 months, remission of hypertension was seen in 42 patients (71%). The declines in the following measurements were significantly higher in patients with remission than those with persistent HTN: aldosterone (p = .029567), angiotensin II (p < .000001), angiotensinogen (p = .000021), neprilysin (p = .000601), renin (p = .000454) and endothelin-1(p = .000030). There was a significantly higher increment in ANP (p = .000002) and a non-significant increment in BNP (p = .081740). Angiotensin II 15 months after LSG and Δ ANP % were significant independent predictors of persistent HTN.

CONCLUSION

In the setting of LSG, aldosterone, angiotensinogen, angiotensin II, renin and neprilysin were significantly lower in patients with remission of HTN after 15 months than those with persistent HTN, and natriuretic peptides were significantly higher. A lower postoperative level of angiotensin II and a larger percentage increment of ANP are independently associated with hypertension remission after LSG.

Increased concentrations of bioactive adrenomedullin subsequently to angiotensin-receptor/neprilysin-inhibitor treatment in chronic systolic heart failure

AIMS

The clinically investigated rationale for neprilysin (NEP)-inhibition by angiotensinreceptor-NEPinhibitor (ARNi) therapy is to induce elevations in endogenous natriuretic peptides. NEP, however, cleaves a broad spectrum of substrates, which partially hold significant implications in heart failure with reduced ejection fraction (HFrEF). The effect of NEP inhibition on these peptides has not been investigated thoroughly. This study explored the response of adrenomedullin (ADM) regulation to the initiation of ARNi.

METHODS

Seventy-four patients with stable HFrEF and initiation of ARNi were prospectively enrolled, 67 patients on continuous angiotensin-converting-enzyme inhibitor(ACEi)/angiotensin-receptor blocker (ARB) therapy served as control. Plasma bioactive-ADM (bio-ADM), mid-regional-pro-ADM (MR-proADM), B-typenatriuretic peptide (BNP) and N-terminal-pro-BNP (NT-proBNP) were determined at baseline, short-term, 1-year and 2-year follow up.

RESULTS

Following ARNi initiation both bio-ADM and MR-proADM concentrations were significantly increased at early and long-term follow up (bio-ADM [pg/mL]: 26.0 [interquartile range {IQR}: 17.7-37.5] vs. 50.8 [IQR: 36.5-78.1] vs. 54.6 [IQR: 42.0-97.1] vs. 57.4 [IQR: 48.5-161.6]; MR-proADM [nmol/L]: 0.87 [IQR: 0.64-1.12] vs. 1.25 [IQR: 0.93-1.79] vs. 1.42 [IQR: 0.95-1.90] vs. 1.60 [IQR: 1.12-2.46], P < .0001 for all). The ratios bio-ADM/MR-proADM and BNP/NT-proBNP increased during ARNi-therapy proving improved availability of bioactive peptides. The proportional increase of bio-ADM markedly exceeded BNP increase. Patients converted to ARNi showed similar biomarker patterns irrespective of baseline renin-angiotensin system blocker therapy, i.e. ACEi or ARB (P > .05 for all), indicating that activation of the ADM-axis arises particularly from NEPinhibition.

CONCLUSION

The significant increase of MR-proADM and bio-ADM together with an elevated bioADM/MR-proADM ratio suggest both enhanced formation and reduced breakdown of bioactive ADM following the initiation of ARNi. Activation of the ADM-axis represents a so far unrecognized effect of ARNi.

Serum neprilysin levels are associated with myocardial stunning after ST-elevation myocardial infarction

Background

Left ventricular remodeling following ST-elevation myocardial infarction (STEMI) is associated with poor outcome, including heart failure (HF). Neprilysin inhibition leads to improved outcome in patients with altered left ventricular ejection fraction (LVEF).

Methods

We aimed to assess the association between serum levels of neprilysin and left ventricular (LV) volumes, function and remodeling in STEMI patients with successful myocardial reperfusion and no clinical sign of HF. Sixty-eight patients were admitted for STEMI and had both plasma neprilysin measurement at baseline and 3D transthoracic echocardiogram at baseline and after a median follow-up of 7 months. We compared 3 groups: a group with a low-level of plasma neprilysin (< 125 pg/mL, i.e. the lower limit of detection of the assay) and the two other groups were defined as being below or above the median value of the remaining samples.

Results

Median age was 58.5 ± 12.8 years and 56 (82.4%) were men. Median LVEF was 45.0 ± 8.5%. Baseline characteristics were comparable between groups (low-level of neprilysin group [≤125 pg/mL, n = 38], medium-level of neprilysin group [126–450 pg/mL, n = 15] and a high-level group [> 450 pg/mL, n = 15]). At baseline there was a non-significant trend towards lower end-diastolic volume (p = 0.07) but significantly lower LVEF in the high neprilysin group (46.4 ± 8.3%, 47.1 ± 8.1% and 39.1 ± 6.9%, p < 0.01). At follow-up, the magnitude of LVEF increase was significantly more important in the high neprilysin group compared to the other groups (p = 0.022 for relative change in LVEF and 6.6 ± 7.3%, 3.6 ± 9.0% and 11.3 ± 8.4%, p = 0.031 for absolute change in LVEF) resulting in similar LVEF levels at follow-up between all groups (53.0 ± 8.9%, 50.6 ± 9.7% and 50.4 ± 9.9%, p = 0.55).

Conclusions

Initial high neprilysin levels may identify patients with stunned myocardium early after STEMI, with a recovery of contractility leading to improved LVEF at follow-up. Future studies will have to assess the role of neprilysin in the setting of STEMI and the potential benefit of its blockade.

Real-Life Indications to Sacubitril/Valsartan Treatment in Patients With Chronic Systolic Heart Failure

OBJECTIVE

International guidelines recommend the introduction of sacubitril/valsartan (Entresto) in patients with heart failure (HF) and reduced ejection fraction (EF), who remain symptomatic, despite optimal uptitrated therapy. The purpose of the following analysis is to verify the real-life eligibility for sacubitril/valsartan in a population of patients suffering from chronic HF, regularly monitored in a single HF clinic and treated according to guideline-directed medical therapy (GDMT).

METHODS

From a total of 1070 patients regularly monitored in our HF Clinic between January 2011 and September 2017, the clinical records of 224 patients with HF and reduced EF on optimized GDMT were retrospectively analyzed.

RESULTS

Of 224 analyzed patients, 75 improved their EF or were asymptomatic after uptitration of GDMT during follow-up; 50 were not on angiotensin-converting enzyme inhibitor or angiotensin receptor blocker for different reasons; 13 patients had systolic blood pressure ≤100 mm Hg, so they were not eligible for sacubitril/valsartan introduction. The remaining patients were still symptomatic (NYHA ≥2), and therefore, sacubitril/valsartan introduction was indicated in these 86 patients (38.4%) of 224 enrolled.

CONCLUSION

In patients with HF and reduced EF, where GDMT is appropriately achieved, indication to sacubitril/valsartan treatment is around 38%.

Angiotensin Receptor-Neprilysin Inhibition (ARNI) in Heart Failure

Recognition that neurohormonal activation plays a central role in the pathogenesis of heart failure (HF) led to the development of angiotensin converting enzyme inhibitors (ACEIs), angiotensin receptor blockers, mineralocorticoid receptor antagonists and beta blockers. While there has been substantial success with these neurohormonal blocking drugs in patients with HF with reduced ejection fraction (HFrEF), persistently high rates of morbidity and mortality in this population underscore the need for more effective therapies. As part of the systemic neurohormonal activation that takes place in patients with HF, systems that counteract the adverse effect of the renin angiotensin aldosterone system (RAAS) and sympathetic nervous system (SNS) are also activated. Evidence that neprilysin metabolizes many of the effector molecules produced by these counter-regulatory systems raised the possibility that inhibition of this enzyme might be beneficial. However, since angiotensin II is a substrate of neprilysin, inhibition of the enzyme alone would increase levels of this peptide. Thus, treatment strategies that combine RAAS blockade with neprilysin inhibition were sought. Recent large scale randomized clinical trials (RCTs) have provided compelling evidence that sacubitril-valsartan, an angiotensin receptor-neprilysin inhibitor (ARNI), is superior to an ACEI in reducing mortality and HF hospitalization and in improving quality of life in patients with stage C HFrEF. In these trials, sacubitril-valsartan was found to be safe and well tolerated. This review presents the rationale for using ARNIs, describes the RCTs showing their efficacy, summarizes updated recommendations from recent guidelines, and provides practical points about ARNI initiation and up-titration.

Neutral Endopeptidase (Neprilysin) in Therapy and Diagnostics: Yin and Yang

Neprilysin (NEP) is a zinc-dependent metalloproteinase that exists in organisms in both transmembrane and soluble forms. NEP substrates are involved in regulating the cardiovascular and nervous systems. In this review, we discuss some of the biochemical characteristics and physiological functions of this enzyme with special emphasis on the use of NEP as a therapeutic target. The history and various physiological aspects of applying NEP inhibitors for treating heart failure and attempts to increase NEP activity when treating Alzheimer's disease using gene and cell therapies are described. Another important issue discussed is the role of NEP as a potential marker for predicting the risk of cardiovascular disease complications. The diagnostic and prognostic performance of soluble NEP in various types of heart failure is analyzed and presented. We also discuss the methods and approaches for measuring NEP activity for prognosis and diagnosis, as well as a possible new role of natriuretic peptides (NEP substrates) in cardiovascular diagnostics.

Bioactive Signaling in Next-Generation Pharmacotherapies for Heart Failure: A Review

Importance

The standard pharmacotherapy for heart failure (HF), particularly HF with reduced ejection fraction (HFrEF), is primarily through the use of receptor antagonists, notably inhibition of the renin-angiotensin system by either angiotensin-converting enzyme inhibition or angiotensin II receptor blockade (ARB). However, the completed Prospective Comparison of ARNI With an ACE-Inhibitor to Determine Impact on Global Mortality and Morbidity in Heart Failure (PARADIGM-HF) trial identified that the use of a single molecule (sacubitril/valsartan), which is an ARB and the neutral endopeptidase inhibitor (NEPi) neprilysin, yielded improved clinical outcomes in HFrEF compared with angiotensin-converting enzyme inhibition alone.

Observations

This review examined specific bioactive signaling pathways that would be potentiated by NEPi and how these would affect key cardiovascular processes relevant to HFrEF. It also addressed potential additive/synergistic effects of ARB. A number of biological signaling pathways that may be potentiated by sacubitril/valsartan were identified, including some novel candidate molecules, which will act in a synergistic manner to favorably alter the natural history of HFrEF.

Conclusions and Relevance

This review identified that activation rather than inhibition of specific receptor pathways provided favorable cardiovascular effects that cannot be achieved by renin-angiotensin system inhibition alone. Thus, an entirely new avenue of translational and clinical research lies ahead in which HF pharmacotherapies will move beyond receptor antagonist strategies.

ARNi: A Novel Approach to Counteract Cardiovascular Diseases

Cardiovascular diseases (CVDs) still represent the greatest burden on healthcare systems worldwide. Despite the enormous efforts over the last twenty years to limit the spread of cardiovascular risk factors, their prevalence is growing and control is still suboptimal. Therefore, the availability of new therapeutic tools that may interfere with different pathophysiological pathways to slow the establishment of clinical CVDs is important. Previously, the inhibition of neurohormonal systems, namely the renin–angiotensin–aldosterone system (RAAS) and the sympathetic nervous system, has proven to be useful in the treatment of many CVDs. Attempts have recently been made to target an additional hormonal system, that of the natriuretic peptides (NPs), which, when dysregulated, can also play a role in the development CVDs. Indeed, a new class of drug, the angiotensin receptor–neprilysin inhibitors (ARNi), has the ability to counteract the effects of angiotensin II as well as to increase the activity of NPs. ARNi have already been proven to be effective in the treatment of heart failure with reduced ejection fraction. New evidence has suggested that, in the next years, the field of ARNi application will widen to include other CVDs, such as heart failure, with preserved ejection fraction and hypertension.

Chronic heart failure: a disease of the brain

The underlying mechanism for clinical and biochemical manifestations of chronic heart failure (HF) may be due in part to neurohumoral adaptations, such as activation of the renin-angiotensin-aldosterone and sympathetic nervous systems in the periphery and the brain. Internet search and discussion with colleagues are the methods for this study. Since chronic HF is associated with autonomic imbalance with increased sympathetic nerve activity and a withdrawal of parasympathetic activity, it may be considered a brain disease. This phenomenon may be the result of an increased systemic and cerebral angiotensin II signaling because plasma angiotensin II is increased in humans and animals with chronic HF. The increase in angiotensin II signaling enhances sympathetic nerve activity through actions on both central and peripheral sites during chronic HF. Activation of angiotensin II signaling in different brain sites such as the paraventricular nucleus (PVN), rostral ventrolateral medulla (RVLM), and area postrema (AP) may increase the release of norepinephrine, oxidative stress, and inflammation leading to increased cardiac contractility. It is possible that blocking angiotensin II type 1 receptors decreases sympathetic nerve activity and cardiac sympathetic afferent reflex when therapy is administered to the PVN. The administration of an angiotensin receptor blocker by injection into the AP activates the sympatho-inhibitory baroreflex indicating that receptor blockers act by increasing parasympathetic activity. In chronic HF, in peripheral regions, angiotensin II elevates both norepinephrine release and synthesis and inhibits norepinephrine uptake at nerve endings, which may contribute to the increase in sympathetic nerve activity. Increased circulating angiotensin II during chronic HF may enhance the sympatho-excitatory chemoreflex and inhibit the sympatho-inhibitory baroreflex resulting in worsening of HF. Increased circulating angiotensin II signaling can directly act on the central nervous system via the subfornical organ and the AP to increase sympathetic outflow resulting in to neurohumoral dysfunction, resulting in to heart failure.

Natural and synthetic peptides in the cardiovascular diseases: An update on diagnostic and therapeutic potentials

Several peptides play an important role in physiological and pathological conditions into the cardiovascular system. In addition to well-known vasoactive agents such as angiotensin II, endothelin, serotonin or natriuretic peptides, the vasoconstrictor Urotensin-II (Uro-II) and the vasodilators Urocortins (UCNs) and Adrenomedullin (AM) have been implicated in the control of vascular tone and blood pressure as well as in cardiovascular disease states including congestive heart failure, atherosclerosis, coronary artery disease, and pulmonary and systemic hypertension. Therefore these peptides, together with their receptors, become important therapeutic targets in cardiovascular diseases (CVDs). Circulating levels of these agents in the blood are markedly modified in patients with specific CVDs compared with those in healthy patients, becoming also potential biomarkers for these pathologies. This review will provide an overview of current knowledge about the physiological roles of Uro-II, UCN and AM in the cardiovascular system and their implications in cardiovascular diseases. It will further focus on the structural modifications carried out on original peptide sequences in the search of analogues with improved physiochemical properties as well as in the delivery methods. Finally, we have overviewed the possible application of these peptides and/or their precursors as biomarkers of CVDs.

Rationale and design of TRANSITION: a randomized trial of pre-discharge vs. post-discharge initiation of sacubitril/valsartan

AIMS

The prognosis after hospitalization for acute decompensated heart failure (ADHF) remains poor, especially <30 days post-discharge. Evidence-based medications with prognostic impact administered at discharge improve survival and hospital readmission, but robust studies comparing pre-discharge with post-discharge initiation are rare. The PARADIGM-HF trial established sacubitril/valsartan as a new evidence-based therapy in patients with heart failure (HF) and reduced left ventricular ejection fraction (<40%) (rEF). In common with other landmark studies, it enrolled patients who were ambulatory at the time of inclusion. In addition, there is also still limited knowledge of initiation and up-titration of sacubitril/valsartan in ACEi/ARB- naïve patients and in de novo HF with rEF patients.

METHODS AND RESULTS

TRANSITION is a multicentre, open-label study in which ~1000 adults hospitalized for ADHF with rEF are randomized to start sacubitril/valsartan in a pre-discharge arm (initiated ≥24 h after haemodynamic stabilization) or a post-discharge arm (initiated within Days 1-14 after discharge). The protocol allows investigators to select the appropriate starting dose and dose adjustments according to clinical circumstances. Over a 10 week treatment period, the primary and secondary objectives assess the feasibility and safety of starting sacubitril/valsartan in-hospital, early after haemodynamic stabilization. Exploratory objectives also include assessment of HF signs and symptoms, readmissions, N-terminal pro-B-type natriuretic peptide and high-sensitivity troponin T levels, and health resource utilization parameters.

CONCLUSIONS

TRANSITION will provide new evidence about initiating sacubitril/valsartan following hospitalization for ADHF, occurring either as de novo ADHF or as deterioration of chronic HF, and in patients with or without prior ACEI/ARB therapy. The results of TRANSITION will thus be highly relevant to the management of patients hospitalized for ADHF with rEF.

Sacubitril and valsartan protect from experimental myocardial infarction by ameliorating oxidative damage in Wistar rats

BACKGROUND

Sacubitril (SAC), a neprilysin inhibitor prevent degradation of neprilysin and activate cGMP signaling pathways leading to rise in blood volume concurrent to blood pressure by means of vasoactive peptides, adrenomedullin, and bradykinin.

OBJECTIVE

The aim of this study was to evaluate the anti-ischemic effects of SAC through inhibiting neprilysin in isoproterenol (ISO) induced myocardial infarction (MI) in Wistar albino rats. ISO (85 mg/kg) was injected subcutaneously at the end of 14 days pre-treatment with SAC and valsartan (VAL).

RESULT

Biochemical investigation revealed that SAC along with VAL significantly prevented the antioxidant enzymes (SOD, Catalase, GR, GPx, GST, and GSH) degradation and malondialdehyde (MDA) induced by ISO intoxication in Wistar rats. Along with this, cardiac biomarkers (LDH, CK-MB, ALT, AST, and ALP) were also significantly ameliorated by SACand VAL in ISO-treated rats. Concurrently, decreased infarction area (IA)and marked reduction in myofibril damage by SACand VAL further supported its protective benefits in MI.

CONCLUSION

Taken together, the results suggest that inhibition of enzyme neprilysin alleviated the ISO induces myocardial damage mediated by its strong antioxidant potential.

Use of sacubitril/valsartan in acute decompensated heart failure: a case report

Refractory heart failure typically requires costly long-term, continuous intravenous inodilator infusions while patients await mechanical circulatory support or cardiac transplantation. The combined angiotensin receptor blocker-neprilysin inhibitor, sacubitril/valsartan, is a novel therapy that can increase levels of endogenous vasoactive peptides. This therapy has been recommended as an alternative agent in patients with chronic heart failure with reduced ejection fraction and New York Heart Association class II-III symptoms. Here, we report a case of a patient with refractory stage D heart failure with reduced ejection fraction who was successfully weaned off continuous intravenous inodilator support using sacubitril/valsartan after prior failed attempts using standard therapies.

Importance of endogenous compensatory vasoactive peptides in broadening the effects of inhibitors of the renin-angiotensin system for the treatment of heart failure

The magnitude of the clinical benefits produced by inhibitors of the renin-angiotensin system in heart failure has been modest, possibly because of the ability of renin-angiotensin activity to escape from suppression during long-term treatment. Efforts to intensify pharmacological blockade by use of dual inhibitors that interfere with the renin-angiotensin system at multiple sites have not yielded consistent incremental clinical benefits, but have been associated with serious adverse reactions. By contrast, potentiation of endogenous compensatory vasoactive peptides can act to enhance the survival effects of inhibitors of the renin-angiotensin system, as evidenced by trials that have compared angiotensin-converting enzyme inhibitors with drugs that inhibit both the renin-angiotensin system and neprilysin. Several endogenous vasoactive peptides act as adaptive mechanisms, and their augmentation could help to broaden the benefits of renin-angiotensin system inhibitors for patients with heart failure.

Focus on the Novel Cardiovascular Drug LZC696: from Evidence to Clinical Consideration

LCZ696, a first-in-class angiotensin receptor neprilysin inhibitor (ARNI), is comprised of the angiotensin receptor blocker valsartan and the neprilysin inhibitor pro-drug sacubitril (AHU377). After oral administration, AHU377 is rapidly metabolized to the active neprilysin inhibitor LBQ657. LCZ696 exerts its effects of diuresis, natriuresis, vasodilation and aldosterone secretion inhibition through simultaneous renin-angiotensin-aldosterone system (RAAS) blockade and natriuretic peptides system (NPS) enhancement. Powerful evidence including PARAMETER and PRARDIGM-HF trials have shown that LCZ696 outperforms RAAS inhibition in treating patients with hypertension and heart failure with reduced ejection fraction (HFrEF), and is well tolerated. In addition, accumulating evidence also suggests its potential use in heart failure with preserved ejection fraction (HFpEF), chronic kidney disease (CKD), post-myocardium infarction (post-MI) and stroke. Both the FDA and CHMP have approved LCZ696 for treatment of HFrEF. Despite all this, some special issues (e.g. use in specific subgroups, adverse events, contraindications and cost-effectiveness analysis) should be considered before its implementation in clinical practice.

Reducing Cardiac Fibrosis: Na/K-ATPase Signaling Complex as a Novel Target

Cardiac fibrosis is a common pathological process in cardiac disease and may lead to heart failure. It can also cause sudden death even in those without cardiac symptoms. Tissue fibrosis can be categorized into two categories: replacement fibrosis (also called reparative fibrosis) and reactive fibrosis. In replacement fibrosis, infiltration of inflammatory cells and accumulation of Extracellular Matrix (ECM) proteins are the initial steps in forming scarlike fibrotic tissue after acute cardiac injury and cardiac cell necrosis. Reactive fibrosis can be formed in response to hormonal change and pressure or volume overload. Experimental studies in animals have identified important pathways such as the Renin-Angiotensin-Aldosterone System (RAAS) and the endothelin pathway that contribute to fibrosis formation. Despite the fact that clinical trials using RAAS inhibitors as therapies for reducing cardiac fibrosis and improving cardiac function have been promising, heart failure is still the leading cause of deaths in the United States. Intensive efforts have been made to find novel targets and to develop new treatments for cardiac fibrosis and heart failure in the past few decades. The Na/K-ATPase, a canonical ion transporter, has been shown to also function as a signal transducer and prolonged activation of Na/K-ATPase signaling has been found to promote the formation of cardiac fibrosis. Novel tools that block the activation of Na/K-ATPase signaling have been developed and have shown promise in reducing cardiac fibrosis. This review will discuss the recent development of novel molecular targets, focusing on the Na/K-ATPase signaling complex as a therapeutic target in treatment of cardiac fibrosis.

Sacubitril/valsartan in heart failure: latest evidence and place in therapy

Despite significant therapeutic advances, patients with chronic heart failure (HF) remain at high risk for HF progression and death. Sacubitril/valsartan (previously known as LCZ696) is a first-in-class medicine that contains a neprilysin (NEP) inhibitor (sacubitril) and an angiotensin II (Ang-II) receptor blocker (valsartan). NEP is an endopeptidase that metabolizes different vasoactive peptides including natriuretic peptides, bradykinin and Ang-II. In consequence, its inhibition increases mainly the levels of both, natriuretic peptides (promoting diuresis, natriuresis and vasodilatation) and Ang-II whose effects are blocked by the angiotensin receptor blocker, valsartan (reducing vasoconstriction and aldosterone release). Results from the 8442 patient PARADIGM-HF study showed in patients with New York Heart Association (NYHA) class II-IV and reduced ejection fraction treated with LCZ696 (versus enalapril), the following benefits: reduction of the risk of death from cardiovascular causes by 20%; reduction of HF hospitalizations by 21%; reduction of the risk of all-cause mortality by 16%. Overall there was a 20% risk reduction on the primary endpoint, composite measure of cardiovascular (CV) death or time to first HF hospitalization. PARADIGM-HF was stopped early after a median follow up of 27 months. Post hoc analyses of PARADIGM-HF as well as the place in therapy of sacubitril/valsartan, including future directions, are included in the present review.

Adrenomedullin 2.0: Adjusting Key Levers for Metabolic Stability

The 52 amino acid peptide hormone adrenomedullin (ADM) plays a major role in the development and regulation of the cardiovascular and lymphatic system and has therefore gained significant interest for clinical applications. Because adrenomedullin exhibits low metabolic stability, enhancement of the plasma half-life is essential for peptide-based drug design. Fluorescently labeled ADM analogues synthesized by Fmoc/t-Bu solid phase peptide synthesis were used to analyze their enzymatic degradation and specific fragmentation pattern in human blood plasma. The determination of important cleavage sites allowed the development of selectively modified peptides in a rational approach. By combination of palmitoylation, lactam-bridging, and Nα-methylation, ADM analogues protected from enzymatic cleavage in human blood were developed and revealed an explicitly elongated half-life of 5 days in comparison to the wild-type in vitro. This triple-modification did not alter the selectivity of the analogues at the AM1 receptor, highlighting their potential for therapeutic applications.

Neprilysin inhibition to treat heart failure: a tale of science, serendipity, and second chances

This review describes the role of neprilysin (also known as neutral endopeptidase or enkephalinase) in the degradation of natriuretic and other vasoactive peptides, including bradykinin and adrenomedullin. The initial development of neprilysin inhibitors, then angiotensin converting enzyme-neprilysin inhibitors and, most recently, the angiotensin receptor neprilysin inhibitor (ARNI) LCZ696 (sacubitril valsartan) as an extension of the nurohumoral basis for the treatment of heart failure is also summarised. Finally, the implications of the compelling benefits of LCZ696 compared with enalapril in the Prospective comparison of ARNI with ACEI to Determine Impact on Global Mortality and morbidity in Heart Failure trial (PARADIGM-HF) is discussed.

Emerging Therapies for Acute and Chronic Heart Failure

Although the period from 1953 to 2001 resulted in the approval of more than 30 medications currently used to treat heart failure (HF), few novel drugs have been approved in the last decade. However, the investigational pipeline for HF medications once again appears promising. In patients with chronic heart failure with reduced ejection fraction (HFrEF), ivabradine and valsartan/sucubitril (LCZ696) were recently approved by the US Food and Drug Administration. Both agents have been shown to reduce the risk of cardiovascular death and HF hospitalization. In the treatment of acute HF, serelaxin and ularitide are the farthest along in development. Both agents have demonstrated favorable effects on surrogate end points and preliminary data suggest a possible mortality benefit with serelaxin. Consequently, phase 3 trials are ongoing to evaluate the effect of serelaxin and ularitide on clinical outcomes. Given the poor history of recent investigational acute HF drugs that have advanced to phase 3/4 studies, enthusiasm for both serelaxin and ularitide must be tempered until these trials are completed.

Bench-to-bedside pharmacology of adrenomedullin

The bioactive peptide adrenomedullin (AM) exerts pleiotropic actions in various organs and tissues. In the heart, AM has an inhibitory effect on ventricular remodeling, suppressing cardiomyocyte hypertrophy and the proliferation of cardiac fibroblasts. This pharmacological property was shown not only in rat models of acute myocardial infarction, but also clinically in patients with this cardiac disease. An originally characterized feature of AM was a potent vasodilatory effect, but this peptide was found to be important for vascular integrity and angiogenesis. AM-induced angiogenesis is involved in tumor growth, while AM inhibits apoptosis of some types of tumor cell. A unique pharmacological property is anti-inflammatory activity, which has been characterized in sepsis and inflammatory bowel diseases; thus, there is an ongoing clinical trial to test the efficacy of AM for patients with intractable ulcerative colitis. These activities are assumed to be mediated via the specific receptor formed by calcitonin receptor-like receptor and receptor activity-modifying protein 2 or 3, while some questions remain to be answered about the molecular mechanisms of this signal transduction system. Taking these findings together, AM is a bioactive peptide with pleiotropic effects, with potential as a therapeutic tool for a wide range of human diseases from myocardial infarction to malignant tumors or inflammatory bowel diseases.

Drug therapies in older adults (part 2)

In this, the second of two articles, we continue our evaluation of drug therapies in older adults. Having previously described the pharmacokinetic and pharmacodynamic consequences of physiological ageing, along with the challenge of appropriate prescribing, we proposed four key questions which should be considered when prescribing for this cohort of the population. Does this agent reflect the priorities of the patient? Are there alternatives - with greater efficacy, effectiveness or tolerability - that might be considered? Are the dose, frequency and formulation appropriate? How does this prescription relate to concurrent medication? We also highlighted the reliance on subgroup analysis to demonstrate the efficacy of drug therapies for older adults in osteoporosis and the underutilisation of appropriate treatments for patients with Alzheimer's disease as a result of flawed guidelines. Here we describe current drug therapies in systolic heart failure, noting the limited inclusion of older adults in key trials, while also reviewing the pharmacological treatment of orthostatic hypotension. In doing so, we advocate the intermittent use of midodrine as a first-line treatment for orthostasis in older adults, counter to the generic guidelines produced by various learned societies, but in keeping with the scant trial data available.

Effects of neutral endopeptidase (neprilysin) inhibition on the response to other vasoactive peptides in small human resistance arteries: studies with thiorphan and omapatrilat

PURPOSE

New compounds with neprilysin or neutral endopeptidase (NEP) inhibiting activity are under clinical investigation in heart failure and hypertension. We investigated the effect of NEP inhibition on the functional vasomotor responses to a range of vasoactive peptides in human blood vessels.

METHODS

Small human resistance arteries from patients with coronary artery disease and preserved left ventricular systolic function were studied. Thiorphan (a NEP inhibitor) was compared with captopril (an ACE inhibitor) and omapatrilat (a dual NEP-ACE inhibitor) with regard to their effects on the response of human arteries to key vasoactive peptides.

RESULTS

As expected, both captopril and omapatrilat (but not thiorphan) inhibited the vasoconstrictor effect of angiotensin I (maximal response [SEM]: 27 ± 8% vehicle, 6 ± 2% captopril, 39 ± 10% thiorphan, 8 ± 7% omapatrilat, P < 0.05). Thiorphan, captopril, and omapatrilat all enhanced the vasodilator response to bradykinin (all P < 0.01). Omapatrilat markedly augmented the vasodilator action of adrenomedullin (P < 0.05), whilst thiorphan and captopril did not. None of the three inhibitors studied affected the vasodilator action of c-type natriuretic peptide, calcitonin gene-related peptide, vasoactive intestinal polypeptide or substance P.

CONCLUSIONS

NEP inhibition with thiorphan modestly augmented the vasodilator action of bradykinin, but did not potentiate the response to adrenomedullin; dual ACE and NEP inhibition with omapatrilat, as expected, markedly augmented the response to bradykinin and also potentiated the effect of adrenomedullin. Thiorphan weakly enhanced the vasoconstrictor response to angiotensin I. Neither omapatrilat nor thiorphan had any effect on the action of a range of other vasoactive peptides including CNP.

Angiotensin-neprilysin inhibition versus enalapril in heart failure

BACKGROUND

We compared the angiotensin receptor-neprilysin inhibitor LCZ696 with enalapril in patients who had heart failure with a reduced ejection fraction. In previous studies, enalapril improved survival in such patients.

METHODS

In this double-blind trial, we randomly assigned 8442 patients with class II, III, or IV heart failure and an ejection fraction of 40% or less to receive either LCZ696 (at a dose of 200 mg twice daily) or enalapril (at a dose of 10 mg twice daily), in addition to recommended therapy. The primary outcome was a composite of death from cardiovascular causes or hospitalization for heart failure, but the trial was designed to detect a difference in the rates of death from cardiovascular causes.

RESULTS

The trial was stopped early, according to prespecified rules, after a median follow-up of 27 months, because the boundary for an overwhelming benefit with LCZ696 had been crossed. At the time of study closure, the primary outcome had occurred in 914 patients (21.8%) in the LCZ696 group and 1117 patients (26.5%) in the enalapril group (hazard ratio in the LCZ696 group, 0.80; 95% confidence interval [CI], 0.73 to 0.87; P<0.001). A total of 711 patients (17.0%) receiving LCZ696 and 835 patients (19.8%) receiving enalapril died (hazard ratio for death from any cause, 0.84; 95% CI, 0.76 to 0.93; P<0.001); of these patients, 558 (13.3%) and 693 (16.5%), respectively, died from cardiovascular causes (hazard ratio, 0.80; 95% CI, 0.71 to 0.89; P<0.001). As compared with enalapril, LCZ696 also reduced the risk of hospitalization for heart failure by 21% (P<0.001) and decreased the symptoms and physical limitations of heart failure (P=0.001). The LCZ696 group had higher proportions of patients with hypotension and nonserious angioedema but lower proportions with renal impairment, hyperkalemia, and cough than the enalapril group.

CONCLUSIONS

LCZ696 was superior to enalapril in reducing the risks of death and of hospitalization for heart failure. (Funded by Novartis; PARADIGM-HF ClinicalTrials.gov number, NCT01035255.).

The expression and regulation of adrenomedullin in the human endometrium: a candidate for endometrial repair

After menstruation, the endometrium has a remarkable capacity for repair, but the factors involved remain undefined. We hypothesize adrenomedullin (AM) plays a role in this process. Premenstrually progesterone levels decline, stimulating prostaglandin (PG) synthesis, vasoconstriction, and hypoxia. This study aimed to determine 1) AM expression throughout the menstrual (M) cycle and 2) its regulation by PG and hypoxia. Human endometrial biopsies (n = 51) were collected with ethical approval and consent. AM mRNA expression was examined by quantitative RT-PCR and was found to be selectively elevated in endometrium from the menstrual (M) phase (P < 0.001). AM immunohistochemical staining was maximal in M and proliferative (P) endometrium. Culture of secretory, but not P, explants with 100 nm PGF(2α) or hypoxia (0.5% O2) increased AM mRNA (P < 0.05). P explants were induced to increase AM expression using in vitro progesterone withdrawal but required the presence of hypoxia (P < 0.05). Short hairpin sequences against hypoxia-inducible factor-1α (HIF-1α) inhibited AM hypoxic up-regulation but did not alter PGF(2α)-induced expression. The AM receptor was immunolocalized to endothelial cells in both lymphatic and blood vessels. Conditioned medium from PGF(2α)-treated cells increased endothelial cell proliferation and branching (P < 0.05). This was abolished by AM receptor antagonists. In conclusion, AM is elevated at the time of endometrial repair and induces both angiogenesis and lymphangiogenesis by stimulating endothelial cell proliferation and tube formation. In the human endometrium, AM expression is up-regulated by two mechanisms: a HIF-1α-mediated hypoxic induction and a HIF-1α-independent PGF(2α) pathway. These physiological mechanisms may provide novel therapeutic targets for disorders such as heavy menstrual bleeding.

Adrenomedullin level in the nasal discharge from allergic rhinitis cohort

Adrenomedullin (AM) is a potent hypotensive and vasodilatory peptide. AM may exert protective actions against the development of many diseases by modulating the blood circulation and body fluid balance. In addition to these functions, it has recently been reported to play important roles in the development of allergy and infections. The purpose of the present study was to demonstrate the existence of AM in the human nasal mucosa and to discuss whether AM might contribute to the pathogenesis of nasal congestion. We measured the total AM concentrations in the nasal discharge. The total AM concentration in the nasal discharge was significantly higher in the non-allergy group (72.1 ± 55.5 fmol/ml) than in the allergy group (37.1 ± 44.2 fmol/ml). By immunohistochemical examination, we identified AM-containing cells in the nasal mucosa from both subjects with and without nasal allergy, and also in nasal polyps. Moreover, those cells were positive for anti-tryptase antibody which recognizes mast cells. In nasal allergy, vasodilatation and increase in vascular permeability are characteristic features of the immediate phase response. Reduced AM levels in the nasal discharge may be associated with attenuation of both of these factors. On the other hand, immunohistochemical analysis demonstrated AM-immunoreactive cells in the chronic phase of rhinosinusitis. In the late and inflammatory phase, mast cells produce AM, which possibly acts as an inhibitor of inflammatory cell migration. In conclusion, AM may be actively secreted into the nasal discharge. AM in the nasal discharge may have protective and anti-inflammatory effects in the nasal mucosa.

Adrenomedullin: regulator of systemic and cardiac homeostasis in acute myocardial infarction

During and following acute myocardial infarction, a variety of endogenous mediators are elevated, one of which is adrenomedullin (AM). AM is a multifunctional peptide that has been identified as having a putative beneficial role following an ischemic insult at both systemic and local levels. Classically described as a potent vasodilator, natriuretic, and diuretic agent, experimental infarct models also demonstrate AM to exhibit antiproliferative and antiapoptotic functions in the myocardium, counterregulating the effects of mediators such as angiotensin-II and endothelin-1. Less well documented are the angiogenic and inflammatory modulating potentials of AM, which may also contribute toward reducing adverse ventricular remodeling. The review examines clinical and experimental studies, looking at the effects of AM and cellular mechanisms that could be involved in mediating cardioprotective effects and ultimately optimizing left ventricular remodeling. Finally, the possibility of enhancing endogenous actions of AM by pharmacological intervention is considered.

Autocrine/paracrine role of inflammation-mediated calcitonin gene-related peptide and adrenomedullin expression in human adipose tissue

Human adipose tissue is a contributor to inflammation- and sepsis-induced elevation of serum procalcitonin (ProCT). Several calcitonin (CT) peptides, including ProCT, CT gene-related peptide (CGRP), and adrenomedullin (ADM) are suspected mediators in human inflammatory diseases. Therefore, we aimed to explore the expression, interactions, and potential roles of adipocyte-derived CT peptide production. Expression of CT peptide-specific transcripts was analyzed by RT-PCR and quantitative real-time PCR in human adipose tissue biopsies and three different inflammation-challenged human adipocyte models. ProCT, CGRP, and ADM secretions were assessed by immunological methods. Adipocyte transcriptional activity, glycerol release, and insulin-mediated glucose transport were studied after exogenous CGRP and ADM exposure. With the exception of amylin, CT peptides were expressed in adipose tissue biopsies from septic patients, inflammation-activated mature explanted adipocytes, and macrophage-activated preadipocyte-derived adipocytes. ProCT and CGRP productions were significantly augmented in IL-1beta and lipopolysaccharide-challenged mesenchymal stem cell-derived adipocytes but not in undifferentiated mesenchymal stem cells. In contrast, ADM expression occurred before and after adipogenic differentiation. Interferon-gamma coadministration inhibited IL-1beta-mediated ProCT and CGRP secretion by 78 and 34%, respectively but augmented IL-1beta-mediated ADM secretion by 50%. Exogenous CGRP and ADM administration induced CT, CGRP I, and CGRP II mRNAs and dose-dependently (10(-10) and 10(-6) m) enhanced glycerol release. In contrast, no CGRP- and ADM-mediated effects were noted on ADM, TNFalpha, and IL-1beta mRNA abundances. In summary, CGRP and ADM are two differentially regulated novel adipose tissue secretion factors exerting autocrine/paracrine roles. Their lipolytic effect (glycerol release) suggests a metabolic role in adipocytes during inflammation.

Matrix metalloproteinase-2 cleavage of adrenomedullin produces a vasoconstrictor out of a vasodilator

MMPs (matrix metalloproteinases) play a major role in the pathogenesis of hypertension by altering the extracellular matrix during cardiovascular remodelling. In the present study we show that MMP-2, but not MMP-9, cleaves the vasodilator peptide AM (adrenomedullin). Addition of the AM-binding protein, complement factor H, prevents this cleavage, providing a hitherto unknown mechanism of action for this binding protein. We identified the signature cleavage fragments and found some of them in human urine, suggesting that MMP-2 processing of AM may occur in vivo. Synthetic AM fragments regulated blood pressure in rats. The larger peptides are vasodilators, as is intact AM, whereas intermediate fragments did not affect blood pressure. In contrast, AM(11-22) elicited vasoconstriction. Studies of AM receptor activation in Rat2 cells confirm that the larger AM cleavage peptides activated this receptor, whereas AM(11-22) did not. The present study defines a new mechanism through which MMP-2 may regulate blood pressure by simultaneously eliminating a vasodilator and generating a vasoconstrictor.

Vascular Actions of Calcitonin Gene-Related Peptide and Adrenomedullin

This review summarizes the receptor-mediated vascular activities of calcitonin gene-related peptide (CGRP) and the structurally related peptide adrenomedullin (AM). CGRP is a 37-amino acid neuropeptide, primarily released from sensory nerves, whilst AM is produced by stimulated vascular cells, and amylin is secreted from the pancreas. They share vasodilator activity, albeit to varying extents depending on species and tissue. In particular, CGRP has potent activity in the cerebral circulation, which is possibly relevant to the pathology of migraine, whilst vascular sources of AM contribute to dysfunction in cardiovascular disease. Both peptides exhibit potent activity in microvascular beds. All three peptides can act on a family of CGRP receptors that consist of calcitonin receptor-like receptor (CL) linked to one of three receptor activity-modifying proteins (RAMPs) that are essential for functional activity. The association of CL with RAMP1 produces a CGRP receptor, with RAMP2 an AM receptor and with RAMP3 a CGRP/AM receptor. Evidence for the selective activity of the first nonpeptide CGRP antagonist BIBN4096BS for the CGRP receptor is presented. The cardiovascular activity of these peptides in a range of species and in human clinical conditions is detailed, and potential therapeutic applications based on use of antagonists and gene targeting of agonists are discussed.

Comparison of vasodilators in human internal mammary artery: ghrelin is a potent physiological antagonist of endothelin-1

1 The potential vasodilator function of the peptide ghrelin, recently identified as the endogenous ligand of the growth hormone secretagogue orphan receptor (GHS-R), was investigated in human endothelium-denuded internal mammary artery. The peptide endothelin-1 (ET-1) is a potent and long-lasting vasoconstrictor. Comparisons were made with established and putative endogenous vasodilators to determine if any could reverse ET-1-induced vasoconstriction in this vessel. 2 Ghrelin (0.1-300 nM) potently dilated 10 nM ET-1-induced constrictions (pD(2) 8.39+/-0.29; E(MAX) 63+/-5.6%; n=9/14, responders/total). 3 ANP (pD(2) 7.75+/-0.14; E(MAX) 106+/-2.0; n=5/5) and CGRP (pD(2) 8.08+/-0.17; E(MAX) 76+/-15% n=5/6) both produced complete reversal of the constrictor response to ET-1 (E(MAX) not significantly different from 100%, P>0.05 one-sample t-test). 4 The following caused partial reversal of the ET-1 response: Adrenomedullin (n=9/9) and two peptides derived from proadrenomedullin, PAMP-12 (n=6/7) and PAMP-20 (n=9/9) (pD(2) values 7.63+/-0.28, 7.97+/-0.23 and 8.51+/-0.29; E(MAX) 58+/-7.3, 54+/-10 and 51+/-7.8% respectively). Unexpectedly, amylin was only 2 fold less potent than CGRP, although there was less than 50% reversal of the ET-1 constriction (pD(2) 7.86+/-0.30; E(MAX) 41+/-5.4%; n=7/9). CNP (n=6/6) also partially reversed constrictions to ET-1 (E(MAX) 53+/-6.3; pD(2) 8.07+/-0.38). 5 BNP (n=4/5) and PGI(2) (n=6/8) were weak vasodilators, since concentration-response curves failed to reach a maximum within the range tested. PGE(2) caused a small dilatation in some vessels (E(MAX) 17+/-2.1%; pD(2) 8.63+/-0.36; n=4/8). 6 We have demonstrated ghrelin to be an effective, endothelium-independent vasodilator of the long-lasting constrictor ET-1 in human arteries producing responses similar to those of adrenomedullin (P>0.05, ANOVA). British Journal of Pharmacology (2002) 136, 1146-1152