Neprilysin inhibition, endorphin dynamics, and early symptomatic improvement in heart failure: a pilot study

Neprilysin inhibitors and risk of Alzheimer's disease: A future perspective

Alzheimer's disease (AD) is a heterogeneous neurodegenerative disease with multifaceted neuropathological disorders. AD is characterized by intracellular accumulation of phosphorylated tau proteins and extracellular deposition of amyloid beta (Aβ). Various protease enzymes, including neprilysin (NEP), are concerned with the degradation and clearance of Aβ. Indeed, a defective neuronal clearance pathway due to the dysfunction of degradation enzymes might be a possible mechanism for the accumulation of Aβ and subsequent progression of AD neuropathology. NEP is one of the most imperative metalloproteinase enzymes involved in the clearance of Aβ. This review aimed to highlight the possible role of NEP inhibitors in AD. The combination of sacubitril and valsartan which is called angiotensin receptor blocker and NEP inhibitor (ARNI) may produce beneficial and deleterious effects on AD neuropathology. NEP inhibitors might increase the risk of AD by the inhibition of Aβ clearance, and increase brain bradykinin (BK) and natriuretic peptides (NPs), which augment the pathogenesis of AD. These verdicts come from animal model studies, though they may not be applied to humans. However, clinical studies revealed promising safety findings regarding the use of ARNI. Moreover, NEP inhibition increases various neuroprotective peptides involved in inflammation, glucose homeostasis and nerve conduction. Also, NEP inhibitors may inhibit dipeptidyl peptidase 4 (DPP4) expression, ameliorating insulin and glucagon-like peptide 1 (GLP-1) levels. These findings proposed that NEP inhibitors may have a protective effect against AD development by increasing GLP-1, neuropeptide Y (NPY) and substance P, and deleterious effects by increasing brain BK. Preclinical and clinical studies are recommended in this regard.

Possible role of LCZ696 in atherosclerosis: new inroads and perspective

LCZ696 blocks both angiotensin receptor type 1 (ATR1) and neprilysin (NEP), which are intricate in the degradation of natriuretic peptides (NPs) and other endogenous peptides. It has been shown NEP inhibitors and LCZ696 could be effectively in the management of atherosclerosis (AS). However, the underlying mechanism of LCZ696 in AS is needed to be clarified entirely. Hence, this review is directed to reconnoiter the mechanistic role of LCZ696 in AS. The anti-inflammatory role of LCZ696 is related to the inhibition of transforming growth factor beta (TGF-β)-activated kinase 1 (TAK) and nod-like receptor pyrin 3 receptor (NLRP3) inflammasome. Moreover, LCZ696, via inhibition of pro-inflammatory cytokines, oxidative stress, apoptosis and endothelial dysfunction can attenuate the development and progression of AS. In conclusion, LCZ696 could be effective in the management of AS through modulation of inflammatory and oxidative signaling. Preclinical and clinical studies are recommended in this regard.

Neprilysin 4: an essential peptidase with multifaceted physiological relevance

Neprilysins are highly conserved ectoenzymes that hydrolyze and thus inactivate signaling peptides in the extracellular space. Herein, we focus on Neprilysin 4 from Drosophila melanogaster and evaluate the existing knowledge on the physiological relevance of the peptidase. Particular attention is paid to the role of the neprilysin in regulating feeding behavior and the expression of insulin-like peptides in the central nervous system. In addition, we assess the function of the peptidase in controlling the activity of the sarcoplasmic and endoplasmic reticulum Ca²⁺ ATPase in myocytes, as well as the underlying molecular mechanism in detail.

Changes in Cardiac Biomarkers in Association with Alterations in Cardiac Structure and Function, and Health Status in HFrEF: The EVALUATE-HF Trial

AIMS

N-terminal pro-B-type natriuretic peptide (NT-proBNP), cardiac troponin T (cTnT) and soluble ST2 (sST2) provide complementary prognostic information in HF with reduced ejection fraction (HFrEF). We aimed to assess the association between changes in these markers with changes in cardiac structure, function and health status.

METHODS AND RESULTS

Patients in the EVALUATE-HF trial (N=464) were randomized to sacubitril/valsartan or enalapril for 12 weeks, followed by 12-week open-label sacubitril/valsartan. Cardiac biomarkers, echocardiography, and Kansas City Cardiomyopathy Questionnaires (KCCQ) were completed at baseline, and after 12 and 24 weeks. A total of 410 patients (88%) had serial biomarker measurements available (mean age 67±9 years, 75% male and 75% white). After 24 weeks of treatment NT-proBNP, sST2 and cTnT decreased by median (Q1,Q3) -31% (-55%,+6%), -6% (-19%,+8%) and -3% (-13%,+8%), respectively (all P<0.001). Decreases in NT-proBNP were associated with reductions in cardiac volumes and improvements in systolic and diastolic function and health status. Decreases in cTnT were associated with reductions in LV mass, but not with changes in LV function or KCCQ. Decreases in sST2 were consistently associated with improvements in health status, but not with measures of cardiac structure or function. There were no effect modification from treatment on the associations investigated (P-for-interaction>0.05).

CONCLUSION

In HFrEF, serial changes in NT-proBNP correlate with changes in several key measures of cardiac structure and health status. cTnT changes correlate with changes in LV mass and sST2 with changes in health status. These data highlight possible complementary pathophysiologic implications of changes NT-proBNP, cTnT and sST2.

The Application of Angiotensin Receptor Neprilysin Inhibitor in Cardiovascular Diseases: A Bibliometric Review From 2000 to 2022

Cardiovascular disease (CVD) has become a huge challenge for the global public health system due to its high morbidity, mortality and severe economic burden. In recent years, angiotensin receptor neprilysin inhibitor (ARNI), a new class of drugs, has shown good therapeutic effects on CVD patients in several clinical studies, reducing the morbidity and mortality of CVD patients. In this study, we retrieved publications on ARNI research in the cardiovascular field from the Web of Science core collection and analyzed the annual output, spatial and temporal distribution, institutions and authors, core journals, keywords and co-cited literature based on CiteSpace. As a result, 604 publications were retrieved, and the number of annual publications generally increased year by year, with the largest number of articles. The analysis of the co-occurrence of output countries and authors showed that a few developed countries such as the United States, Canada, and United Kingdom are the most active in this field, forming academic groups represented by John Joseph Valentine McMurray and Scott D. Solomon, and New England Journal of Medicine, Cirulation, and Journal of the American College of Cardiology are the most popular journals in the field, with research hotspots focused on ARNI in the treatment of total ejection fraction heart failure, hypertension and its target organ damage, with the potential for future benefit throughout the cardiovascular event chain as research progresses. This study reveals the prospective application of ARNI in the cardiovascular field and the research hotspots, providing broader and deeper guidance for its use in the clinic, which is beneficial to improve the treatment and prognosis of CVD patients.

Endogenous opiates and behavior: 2020

This paper is the forty-third consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2020 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).

Finding a reliable assay for soluble neprilysin

BACKGROUND

Lack of validation and standardization of research-use-only (RUO) immunoassays brings with it inherent threats to authenticity and functional quality. Poor correlation between different commercial neprilysin RUO immunoassays is concerning and discordant findings need to be resolved. We seek to identify and validate reliable neprilysin immunoassays to strengthen the scientific rigor and reproducibility of neprilysin-related investigation and of biomarker research in general.

METHODS

Soluble neprilysin (sNEP) concentrations were determined in cohorts (n = 532) from Spain (Cohort 1), New Zealand (NZ, Cohort 2) and Singapore (Cohort 3), using commercial kits from six vendors. Apparent sNEP concentrations were correlated between different assays and with plasma neprilysin activity. Assay reliability was further validated by performance verification, MS analysis and cross-reactivity tests.

RESULTS

sNEP in Cohorts 1 and 2 measured concurrently in Spain and NZ showed significant inter-laboratory correlation only for the Aviscera Bioscience sNEP ELISA SK00724-01. Neprilysin concentrations obtained with the R&D systems and SK00724-01 ELISAs correlated with each other but not with neprilysin activity. In Cohort 3, sNEP concentrations from the Perkin Elmer AlphaLISA and Biotechne ELLA assays agreed (r = 0.89) and both correlated with neprilysin activity (r = 0.87, 0.77 respectively). MS analysis detected authentic neprilysin in the AlphaLISA kit calibrator and in antibody pull-down material from human plasma. The AlphaLISA assay performed within acceptable limits (spike and recovery, dilutional linearity, inter- and intra-assay CV) and showed no cross-reactivity against neprilysin substrates and closely-related analogues.

CONCLUSION

AlphaLISA and ELLA assays provide reliable measures of sNEP concentrations. Reliability of other commercial neprilysin assays remains in question.

Cardiovascular therapeutics: A new potential for anxiety treatment?

Besides the well‐recognized risk factors, novel conditions increasing cardiovascular morbidity and mortality are emerging. Undesirable emotions and behavior such as anxiety and depression, appear to participate in worsening cardiovascular pathologies. On the other hand, deteriorating conditions of the heart and vasculature result in disturbed mental and emotional health. The pathophysiological background of this bidirectional interplay could reside in an inappropriate activation of vegetative neurohormonal and other humoral systems in both cardiovascular and psychological disturbances. This results in circulus vitiosus potentiating mental and circulatory disorders. Thus, it appears to be of utmost importance to examine the alteration of emotions, cognition, and behavior in cardiovascular patients. In terms of this consideration, recognizing the potential of principal cardiovascular drugs to interact with the mental state in patients with heart or vasculature disturbances is unavoidable, to optimize their therapeutic benefit. In general, beta‐blockers, central sympatholytics, ACE inhibitors, ARBs, aldosterone receptor blockers, sacubitril/valsartan, and fibrates are considered to exert anxiolytic effect in animal experiments and clinical settings. Statins and some beta‐blockers appear to have an equivocal impact on mood and anxiety and ivabradine expressed neutral psychological impact. It seems reasonable to suppose that the knowledge of a patient's mood, cognition, and behavior, along with applying careful consideration of the choice of the particular cardiovascular drug and respecting its potential psychological benefit or harm might improve the individualized approach to the treatment of cardiovascular disorders.

Neprilysin inhibition does not alter dynamic of proenkephalin-A 119-159 and pro-substance P in heart failure

AIMS

As NEP degrades many substrates, the specific therapeutic mechanism of NEP inhibition with angiotensin receptor neprilysin inhibitor (ARNi) in heart failure with reduced ejection fraction (HFrEF) is not entirely evident. The aim of this study was to investigate the response of two substrates of NEP-the tachykinin and enkephalin systems-to the initiation of ARNi therapy in HFrEF.

METHODS AND RESULTS

Between 2016 and 2018, 141 consecutive patients with stable HFrEF [74 with initiation of ARNi and 67 controls on continuous angiotensin converting enzyme inhibitor (ACEi) or angiotensin receptor blocker (ARB) therapy] were prospectively enrolled. Plasma proenkephalin-A 119-159 (PENK) and pro-substance P (pro-SP) were serially determined. Proenkephalin-A 119-159 and pro-SP correlated strongly with each other (r_s  = 0.67, P < 0.001) and kidney function (r_s  = -0.66, P < 0.001 and r_s  = -0.54, P < 0.001) and modestly with NT-proBNP (r_s  = 0.32, P < 0.001 and r_s  = 0.24, P = 0.006, respectively). Concentrations of circulating PENK were slightly elevated after 1 and 2 year follow-up compared with baseline (BL) [BL median: 67.4 pmol/L (IQR: 57.3-89.8), 1 year: 83.5 pmol/L (IQR: 62.4-111.6), 2 years: 92.3 pmol/L (IQR: 63.1-101.9); BL vs. 1 year: P = 0.017 and BL vs. 2 years: P = 0.019] in the overall analysis, but lost significance at 2 year follow-up when assessed in paired subanalysis (P = 0.116). Plasma pro-SP levels remained comparable during the entire follow-up [BL median: 78.3 pmol/L (IQR: 67.9-90.6), 1 year: 75.9 pmol/L (IQR: 58.6-96.3), 2 years: 79.7 pmol/L (IQR: 59.9-105.3); P = ns for both timepoints]. Biomarker patterns of ARNi patients were independent from baseline therapy, that is, ACEi or ARB (P > 0.05 between groups).

CONCLUSIONS

Although enkephalins and SP are known substrates of NEP, NEP inhibition by ARNi does not clearly affect the circulating precursors PENK and pro-SP in HFrEF.

CD10 (neprilysin) expression: a potential adjunct in the distinction of hibernoma from morphologic mimics

Although the morphologic diagnosis of hibernoma is usually straightforward, some hibernomas have atypical morphologic features, mimicking atypical lipomatous tumors/well-differentiated liposarcomas (ALT/WDLs). In addition, the multivacuolated brown fat cells may be mistaken for lipoblasts by pathologists, especially those without significant soft tissue tumor exposure. Thus, we continue to receive in consultation cases of hibernoma sent for MDM2 fluorescence in situ hybridization testing to exclude ALT/WDL. Testing hibernomas for MDM2 amplification, however, adds cost and delays the final diagnosis. Recently, we have noted expression of neprilysin (CD10, CALLA), a zinc-dependent metalloproteinase involved in the inactivation of various peptide hormones, in brown fat cells, and wished to explore the potential utility of this widely available, inexpensive ancillary test in the differential diagnosis of hibernoma. Formalin-fixed, paraffin-embedded tissue sections from well-characterized cases of hibernoma (n = 48), brown fat (n = 21), ALTs/WDLs (n = 17), pleomorphic liposarcomas (PLPSs) (n = 6), lipomas (n = 5), and fat necrosis (n = 5) were immunostained for CD10, using a commercially available antibody and routine laboratory protocols. CD10 expression was evaluated in both adipocytes and in surrounding stromal cells. The hibernomas occurred in 28 men and 20 women, ranging from 11 to 76 years of age and involved the extremities (n = 25), pelvis (n = 7), abdomen/pelvis/retroperitoneum (n = 7), head and neck region (n = 6), back (n = 2), and chest (n = 1). All showed diffuse, strong CD10 expression in multivacuolated brown fat cells and in the majority of adjacent univacuolated fat cells. Brown adipose tissue from various anatomic structures showed an identical pattern of immunoreactivity. In contrast, CD10 expression was present in the adipocytes of only 3 of 17 (18%) ALTs/WDLs and was absent in lipomas and fat necrosis. Lipoblasts expressed CD10 in 3 PLPSs. Expression of CD10 by surrounding fibroblastic stromal cells was more widespread, present in 13 hibernomas, 10 ALTs/WDLs, 1 instance of fat necrosis, 6 PLPSs, and 4 examples of brown fat. We conclude that immunohistochemistry for CD10 may represent a useful, rapid and inexpensive ancillary test in the differential diagnosis of hibernoma from potential morphologic mimics, especially when morphologic features favor hibernoma. CD10 expression in adipocytes, however, should be rigorously distinguished from fibroblastic stromal cell CD10 expression, a nonspecific finding.

Improvement of Health Status Following Initiation of Sacubitril/Valsartan in Heart Failure and Reduced Ejection Fraction

BACKGROUND

Treatment of heart failure with reduced ejection fraction (EF) may improve patient-reported health outcomes.

OBJECTIVES

The purpose of this study was to determine timing and magnitude of change in Kansas City Cardiomyopathy Questionnaire (KCCQ)-23 scores following initiation of sacubitril/valsartan and interaction with change in amino-terminal pro-B-type natriuretic peptide (NT-proBNP) concentrations.

METHODS

From a single-arm, open-label study of patients initiated on sacubitril/valsartan, KCCQ-23 scores and NT-proBNP were obtained at baseline and follow-up through 12 months. Cross-sectional and longitudinal analyses evaluated magnitude and rate of change in KCCQ-23 scores and associations with NT-proBNP. Patient-level data from the randomized EVALUATE-HF study were used as historic controls.

RESULTS

The analysis cohort (n = 678, age 64.7 years, 71.5% men, EF 28.9%) had a baseline KCCQ-23 overall score (OS) of 65.6. Following sacubitril/valsartan initiation, the majority (n = 412; 60.8%) of participants experienced a rise in KCCQ-23 OS ≥10 points; 26.0% increased by ≥20 points. Comparable improvement in KCCQ-23 scores was seen in various subgroups. Change in KCCQ-23 OS was inversely associated with change in circulating NT-proBNP concentrations. Among a control group of patients in EVALUATE-HF, linear rate of change in KCCQ-12 OS/14-day interval in the enalapril arm was 0.37 points (p = 0.06), whereas in the sacubitril/valsartan arm, scores increased at a rate of 1.19 points (p < 0.001), nearly identical to this dataset (1.08 points; p < 0.001).

CONCLUSIONS

Treatment of heart failure with reduced EF with sacubitril/valsartan is associated with rapid and significant improvement in KCCQ-23 scores which was significantly related to change in NT-proBNP. (Effects of Sacubitril/Valsartan Therapy on Biomarkers, Myocardial Remodeling and Outcomes [PROVE-HF]; NCT02887183).

Neprilysin as a Biomarker: Challenges and Opportunities

Neprilysin (NEP) inhibition is a successful novel therapeutic approach in heart failure with reduced ejection fraction. Assessing individual NEP status might be important for gathering insights into mechanisms of disease and optimising individualised patient care. NEP is a zinc-dependent multisubstrate-metabolising oligoendopeptidase localised in the plasma membrane with the catalytic site facing the extracellular space. Although NEP activity in vivo is predominantly tissue-based, NEP can be released into the circulation via ectodomain shedding and exosomes. Attempts to determine circulating NEP concentrations and activity have not yet resulted in convincingly coherent results relating NEP biomarkers to heart failure disease severity or outcomes. NEP is naturally expressed on neutrophils, opening up the possibility of measuring a membrane-associated form with integrity. Small studies have linked NEP expression on neutrophils with inflammatory state and initial data might indicate its role in heart failure with reduced ejection fraction. Future studies need to assess the regulation of systemic NEP activity, which is assumed to be tissue-based, and the relationship of NEP activation with disease state. The relationship between tissue NEP activity and easily accessible circulating NEP biomarkers and the impact of the latter remains to be established.

Neprilysin inhibition, endorphin dynamics, and early symptomatic improvement in heart failure: a pilot study

Aim

Sacubitril/valsartan is a first‐in‐class angiotensin receptor‐neprilysin inhibitor developed for the treatment of heart failure with reduced ejection fraction. Its benefits are achieved through the inhibition of neprilysin (NEP) and the specific blockade of the angiotensin receptor AT1. The many peptides metabolized by NEP suggest multifaceted potential consequences of its inhibition. We sought to evaluate the short‐term changes in serum endorphin (EP) values and their relation with patients' physical functioning after initiation of sacubitril/valsartan treatment.

Methods and results

A total of 105 patients with heart failure with reduced ejection fraction, who were candidates for sacubitril/valsartan treatment, were included in this prospective, observational, multicentre, and international study. In a first visit, and in agreement with current guidelines, treatment with angiotensin‐converting enzyme inhibitors or angiotensin receptor blocker was replaced by sacubitril/valsartan because of clinical indication by the responsible physician. By protocol, patients were reevaluated at 30 days after the start of sacubitril/valsartan. Serum levels of α‐ (α‐EP), γ‐Endorphin (γ‐EP), and soluble NEP (sNEP) were measured using enzyme‐linked immunoassays. New York Heart Association (NYHA) functional class was used as an indicator of patient's functional status. Baseline median levels of circulating α‐EP, γ‐EP, and sNEP were 582 (160–772), 101 (37–287), and 222 pg/mL (124–820), respectively. There was not a significant increase in α‐EP nor γ‐EP serum values after sacubitril/valsartan treatment (P value = 0.194 and 0.102, respectively). There were no significant differences in sNEP values between 30 days and baseline (P value = 0.103). Medians (IQR) of Δα‐EP, Δγ‐EP, and ΔsNEP between 30 days and baseline were 9.3 (−34 − 44), −3.0 (−46.0 − 18.9), and 0 units (−16.4 − 157.0), respectively. In a pre–post sacubitril/valsartan treatment comparison, there was a significant improvement in NYHA class, with 36 (34.3%) patients experiencing improvement by at least one NYHA class category. Δα‐EP and ΔsNEP showed to be significantly associated with NYHA class after 30 days of treatment (P = 0.014 and P < 0.001, respectively). Δα‐EP was linear and significantly associated with NYHA class improvement after 30 days of sacubitril/valsartan treatment.

Conclusions

These preliminary data suggest that beyond the haemodynamic benefits achieved with sacubitril/valsartan, the altered cleavage of endorphin peptides by NEP inhibition may participate in patients' symptoms improvement.