Neutral Endopeptidase Research Articles

DYSREGULATION OF THE Aβ DEGRADING ENZYME NEPRILYSIN (MME) COULD CONTRIBUTE TO ALZHEIMER’S DISEASE

Alzheimer's disease (AD) is the foremost world-wide cause of age-related dementia. Its global prevalence constantly on the increase due to an aging population. Among the dementias, AD is characterized by accumulation of amyloid β (Aβ) plaques and aggregates of hyper-phosphorylated microtubule-associated protein tau (p-τ) in brains. Nevertheless, the underlying pathogenesis of AD is presently unknown, particularly the most common form of AD, late-onset. Even though genetic, epigenetic, and environmental factors play critical roles in AD etiology (Maloney and Lahiri, Lancet Neurol-2016), specific triggers are still unknown. We hypothesize that AD results from dysregulation of key biochemical pathways, particularly through regulatory molecules, such as non-coding RNAs, including microRNA (Long, Maloney, Rogers and Lahiri, Mol. Psychiatry-2018). We further posit that disruption of miRNA regulation of membrane metallo-endopeptidase (MME), or neprilysin could contribute to Aβ accumulation and hence AD pathogenesis, since MME is an important Aβ-clearing enzyme. Using the bioinformatics tools we predicted miRNA binding sites on the MME mRNA 3’-untranslated region (3’-UTR). We made neuronally-differentiated human neuroblastoma (SK-N-SH) cells with all-trans retinoic acid (ATRA). We transfected the differentiated cells with either siRNA against MME or candidate miRNAs. We assayed levels of MME mRNA and its protein by qRT-PCR and Western blotting, respectively. Upon identifying miR-181d as a functional candidate, we tested sequence specificity and miR-181d activity with reporter gene- MME 3’-UTR constructs. We also measured MME protein levels in several human fetal tissues. While several miRNAs were predicted to target the MME 3’-UTR, including miR-9, miR-181d, miR-128 and miR-216, only miR-181d treatment produced significant reduction of MME mRNA and protein levels in neuronal cultures. The functional assays further elucidated miR181d activity. MME is expressed in a variety of human organs, with the highest expression in kidney. Notably, miR-181d can down-regulate MME mRNA and protein through the specific target site within MME 3’-UTR. MME is a key Aβ-degrading enzyme involved in AD. Dysregulation by (presumably excess) miR-181d could contribute to AD pathogenesis. Supported by the NIA/NIH grant to DKL.

Neuroprotection induced by Navβ2‑knockdown in APP/PS1 transgenic neurons is associated with NEP regulation.

Voltage‑gated sodium channel β2 (Navβ2), as an unconventional substrate of β‑site amyloid precursor protein cleaving enzyme1, is involved in regulating the neuronal surface expression of sodium channels. A previous study demonstrated that knockdown of Navβ2 protected neurons and induced spatial cognition improvement by partially reducing pathological amyloidogenic processing of amyloid precursor protein (APP) in aged APP/presenilin1 (PS1) transgenic mice. The present study aimed to investigate whether Navβ2 knockdown altered APP metabolism via regulation of the Aβ‑degrading enzyme neprilysin (NEP). APPswe/PS1ΔE9 mice (APP/PS1 transgenic mice with a C57BL/6J genetic background) carrying a Navβ2‑knockdown mutation (APP/PS1/Navβ2‑kd) or without Navβ2 knockdown (APP/PS1) were used for cell culture and further analysis. The present results demonstrated that in APP/PS1 mouse‑derived neurons, Navβ2 knockdown partially reversed the reduction in pathological APP cleavage, and the recovery of neurite extension and neuron area. Additionally, Navβ2 knockdown increased NEP activity and levels, and the levels of intracellular domain fragment binding to the NEP promoter. The present findings suggested that knockdown of Navβ2 reversed the APP/PS1 mutation‑induced deficiency in amyloid β degradation by regulating NEP.

Obesity and aging affects skeletal muscle renin-angiotensin system and myosin heavy chain proportions in pre-diabetic Zucker rats.

There is a gap in the knowledge regarding regulation of local renin-angiotensin system (RAS) in skeletal muscle during development of obesity and insulin resistance in vivo. This study evaluates the obesity- and age-related changes in the expression of local RAS components. Since RAS affects skeletal muscle remodelling, we also evaluated the muscle fibre type composition, defined by myosin heavy chain (MyHC) mRNAs and protein content. Gene expressions were determined by qPCR and/or Western blot analysis in musculus quadriceps of 3- and 8-month-old male obese Zucker rats and their lean controls. The enzymatic activity of aminopeptidase A (APA) was determined flourometrically. Activation of renin receptor (ReR)/promyelocytic leukaemia zinc finger (PLZF) negative feedback mechanism was observed in obesity. The expression of angiotensinogen and AT1 was downregulated by obesity, while neutral endopeptidase and AT2 expressions were upregulated in obese rats with aging. Skeletal muscle APA activity was decreased by obesity, which negatively correlated with the increased plasma APA activity and plasma cholesterol. The expression of angiotensin-converting enzyme (ACE) positively correlated with MyHC mRNAs characteristic for fast-twitch muscle fibres. The obesity- and age-related alterations in the expression of both classical and alternative RAS components suggest an onset of a new equilibrium between ACE/AngII/AT1 and ACE2/Ang1-7/Mas at lower level accompanied by increased renin/ReR/PLZF activation. Increased APA release from the skeletal muscle in obesity might contribute to increased plasma APA activity. There is a link between reduced ACE expression and altered muscle MyHC proportion in obesity and aging.

Apelin protects against abdominal aortic aneurysm and the therapeutic role of neutral endopeptidase resistant apelin analogs.

Abdominal aortic aneurysm (AAA) remains the second most frequent vascular disease with high mortality but has no approved medical therapy. We investigated the direct role of apelin (APLN) in AAA and identified a unique approach to enhance APLN action as a therapeutic intervention for this disease. Loss of APLN potentiated angiotensin II (Ang II)-induced AAA formation, aortic rupture, and reduced survival. Formation of AAA was driven by increased smooth muscle cell (SMC) apoptosis and oxidative stress in Apln-/y aorta and in APLN-deficient cultured murine and human aortic SMCs. Ang II-induced myogenic response and hypertension were greater in Apln-/y mice, however, an equivalent hypertension induced by phenylephrine, an α-adrenergic agonist, did not cause AAA or rupture in Apln-/y mice. We further identified Ang converting enzyme 2 (ACE2), the major negative regulator of the renin-Ang system (RAS), as an important target of APLN action in the vasculature. Using a combination of genetic, pharmacological, and modeling approaches, we identified neutral endopeptidase (NEP) that is up-regulated in human AAA tissue as a major enzyme that metabolizes and inactivates APLN-17 peptide. We designed and synthesized a potent APLN-17 analog, APLN-NMeLeu9-A2, that is resistant to NEP cleavage. This stable APLN analog ameliorated Ang II-mediated adverse aortic remodeling and AAA formation in an established model of AAA, high-fat diet (HFD) in Ldlr-/- mice. Our findings define a critical role of APLN in AAA formation through induction of ACE2 and protection of vascular SMCs, whereas stable APLN analogs provide an effective therapy for vascular diseases.

Neprilysin inhibitor from herbal compounds as the latest adjuvant treatment of chronic heart failure

Neprilysin (NEP) is an endopeptidase that metabolizes vasoactive peptides such as natriuretic peptides. Angiotensin Receptor-Neprilysin Inhibitor (ARNI) is an alternative therapy for chronic heart failure (CHF) which is better than angiotensin receptor antagonist therapy alone. This study aimed to identify herbal compounds as in silico NEP inhibitor for adjuvant treatment of CHF. In this study, structure of NEP was obtained from Protein Data Bank (5JMY) and sacubitril as a standard ligand was obtained from PubChem database (9811834). Indonesian herbal compounds were derived from the HerbalDB database that met criteria of Lipinski’s rule. Binding affinity and sites were determined using the AutoDock Vina software. Interaction of herbal compounds and NEP were visualized using the PyMol software. Indonesian herbal compounds with the same binding site at Arg102 dan Arg110 amino acids with sacubitril (-6.73 ± 0.06 Kcal/mol) was NSC9324 (-7.07 ± 0.05 Kcal/mol). From 517 herbal compounds, NSC93241 had similar conformation to the standard ligand. NSC93241 has similar molecular formula and molecular weight to herbal plant (Ruscus aculeatus Linn or Butcher’s broom). NSC93241 potentially becomes an NEP inhibitor in silico for adjuvant treatment of CHF. Further investigation is required for evaluation of the antagonist effect of this compound towards NEP.

Improving the Theranostic Potential of Exendin 4 by Reducing the Renal Radioactivity through Brush Border Membrane Enzyme-Mediated Degradation

As highly expressed in insulinomas, the glucagon-like peptide-1 receptor (GLP-1R) is believed to be an attractive target for diagnosis, localization, and treatment with radiolabeled exendin 4. However, the high and persistent radioactivity accumulation of exendin 4 in the kidneys limits accurate diagnosis and safe, as well as effective, radiotherapy in insulinomas. In this study, we intend to reduce the renal accumulation of radiolabeled exendin 4 through degradation mediated by brush border membrane enzymes. A new exendin 4 ligand NOTA-MVK-Cys40-Leu14-Exendin 4 containing Met-Val-Lys (MVK) linker between the peptide and 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA) chelator was synthesized and labeled with 68Ga. The in vitro mouse serum stability and cell binding affinity of the tracer were evaluated. Initial in vitro cleavage of the linker was determined by incubation of a model compound Boc-MVK-Dde with brush border membrane vesicles (BBMVs) with and without the inhibitor of neutral endopeptidase (NEP). Further cleavage studies were performed with the full structure of NOTA-MVK-Cys40-Leu14-Exendin 4. Kidney and urine samples were collected in the in vivo metabolism study after intravenous injection of 68Ga-NOTA-MVK-Cys40-Leu14-Exendin 4. The microPET images were acquired in INS-1 tumor model at different time points; the radioactivity uptake of 68Ga-NOTA-MVK-Cys40-Leu14-Exendin 4 in tumor and kidneys were determined and compared with the control radiotracer without MVK linker. 68Ga-NOTA-MVK-Cys40-Leu14-Exendin 4 was stable in mouse serum. The MVK modification did not affect the affinity of NOTA-MVK-Cys40-Leu14-Exendin 4 toward GLP-1R. The in vitro cleavage study and in vivo metabolism study confirmed that the MVK sequence can be recognized by BBM enzymes and cleaved at the amide bond between Met and Val, thus releasing the small fragment containing Met. MicroPET images showed that the tumor uptake of 68Ga-NOTA-MVK-Cys40-Leu14-Exendin 4 was comparable to that of the control, while the kidney uptake was significantly reduced. As a result, more favorable tumor to kidney ratios were achieved. In this study, a novel exendin 4 analogue, NOTA-MVK-Cys40-Leu14-Exendin 4, was successfully synthesized and labeled with 68Ga. With the cleavable MVK sequence, this ligand could be cleaved by the enzymes on kidneys, and releasing the fragment of 68Ga-NOTA-Met-OH, which will rapidly excrete from urine. As the high and consistent renal radioactivity accumulation could be significantly reduced, NOTA-MVK-Cys40-Leu14-Exendin 4 shows great potential in the diagnosis and radiotherapy for insulinoma.

New drugs: big changes in conservative heart failure therapy?

Summary During the last 20 years, the prognosis for heart failure (HF) with reduced ejection fraction has steadily improved due to advances in drug treatment and the consistent implementation of guideline-recommended evidence-based drug therapy. Nevertheless, the morbidity and mortality rates of patients with HF can still be improved. The prevalence of HF is high and continues to increase steadily. Thus, timely and efficient drug treatment plays a central role in improving the quality of life and prognosis for patients with HF. Current therapeutic concepts combine inhibition of the renin–angiotensin–aldosterone system with blockage of the sympathetic system. New therapeutic approaches such as selective heart rate reduction, attenuation of the degradation of natriuretic peptides by neutral endopeptidase inhibition and treatment of comorbidities (e.g. iron deficiency, diabetes mellitus, hyperkalaemia) have led to a further improvement in the survival, time-out-of hospital and quality of life of affected patients. The goal of this article was to give an overview of the current standard drug therapy for HF and the value of new therapeutic approaches implemented in recent years.

Structures of soluble rabbit neprilysin complexed with phosphoramidon or thiorphan.

Neutral endopeptidase (neprilysin; NEP) is a proteinase that cleaves a wide variety of peptides and has been implicated in Alzheimer's disease, cardiovascular conditions, arthritis and other inflammatory diseases. The structure of the soluble extracellular domain (residues 55-750) of rabbit neprilysin was solved both in its native form at 2.1 Å resolution, and bound to the inhibitors phosphoramidon and thiorphan at 2.8 and 3.0 Å resolution, respectively. Consistent with the extracellular domain of human neprilysin, the structure reveals a large central cavity which contains the active site and the location for inhibitor binding.

Membrane Metalloendopeptidase (MME) Suppresses Metastasis of Esophageal Squamous Cell Carcinoma (ESCC) by Inhibiting FAK-RhoA Signaling Axis

Esophageal squamous cell carcinoma (ESCC) is a typical neoplastic disease and a frequent cause of death in China. Although great achievements have been made in diagnostic strategies and combination therapies in recent years, the prognosis of ESCC is still poor. Metastasis/recurrence has been the major factor responsible for poor prognosis. However, the underlying mechanism of ESCC dissemination remains elusive. Membrane metalloendopeptidase (MME) is a transmembrane glycoprotein that degrades a number of substrates. This study's results indicated that the down-regulation of MME is significantly associated with advanced clinical stage (P<0.05) and lymph node metastasis (P<0.05). The down-regulation of MME in ESCC tumor tissues is correlated to poorer prognosis of the patients. Functional studies demonstrated that MME could significantly inhibit ESCC tumor cell metastasis invitro and invivo. MME overexpression could also interrupt ESCC tumor cell adhesion. Mechanistically, MME inhibits the phosphorylation of FAK thus interrupting the FAK-RhoA axis, which is important in cell movement. Taken together, these data show that MME regulates ESCC via FAK-RhoA axis. Highexpression of MME may indicate a beneficial outcome for patients.

Placental Syncytiotrophoblast-Derived Extracellular Vesicles Carry Active NEP (Neprilysin) and Are Increased in Preeclampsia.

NEP (neprilysin) is a widely expressed membrane-bound metalloprotease, which binds and cleaves a variety of peptides including vasodilators, natriuretics, and diuretics. Higher levels of NEP result in hypertension-a cardinal feature of the placental disease preeclampsia. Syncytiotrophoblast-derived extracellular vesicles (EVs), comprising microvesicles and exosomes, are released into the peripheral circulation in pregnancy and are postulated as a key mechanism coupling placental dysfunction and maternal phenotype in preeclampsia. We aimed to determine whether higher levels of active NEP are found in syncytiotrophoblast-derived EVs in preeclampsia compared with normal pregnancy. Using immunostaining and Western blotting, we first demonstrated that NEP levels are greater not only in preeclampsia placental tissue but also in syncytiotrophoblast-derived microvesicles and exosomes isolated from preeclampsia placentas ( P<0.05, n=5). We confirmed placental origin using antibody-coated magnetic beads to isolate NEP-bound vesicles, finding that they stain for placental alkaline phosphatase. NEP on syncytiotrophoblast-derived EVs is active and inhibited by thiorphan ( P<0.01, n=3; specific inhibitor). Syncytiotrophoblast-derived microvesicles, isolated from peripheral plasma, demonstrated higher NEP expression in preeclampsia using flow cytometry ( P<0.05, n=8). We isolated plasma exosomes using size-exclusion chromatography and showed greater NEP activity in preeclampsia ( P<0.05, n=8). These findings show that the placenta releases active NEP into the maternal circulation on syncytiotrophoblast-derived EVs, at significantly greater levels in preeclampsia. NEP has pathological roles in hypertension, heart failure, and amyloid deposition, all of which are features of preeclampsia. Circulating syncytiotrophoblast-derived EV-bound NEP thus may contribute to the pathogenesis of this disease.

Neutral endopeptidase (NEP) inhibitors – thiorphan, sialorphin, and its derivatives exert anti-proliferative activity towards colorectal cancer cells in vitro

Neutral endopeptidase (NEP) is an enzyme implicated in development of different tumors, e.g. colorectal cancer (CRC). In this study, the anti-cancer effects of NEP inhibitors, thiorphan (synthetic compound) and sialorphin (naturally occurring pentapeptide) on CRC cells were investigated. Moreover, we synthesized some derivatives of sialorphin (alanine scan analogues: AHNPR, QANPR, QHAPR, QHNAR; N-acetylated sialorphin; C-amidated sialorphin, and C-amidated alanine scan analogues) to examine the biological activity of these inhibitors on CRC cells. The cytotoxic activity of the NEP inhibitors against CRC cell lines (SW620 and LS180) and normal human fibroblasts (HSF) was evaluated. Additionally, the influence of NEP inhibitors on proliferation, cell cycle progression, induction of apoptosis, and the level of phosphorylation of MAP kinases and mTORC1 signaling pathway proteins in CRC cells were examined. The NEP inhibitors were non-cytotoxic to HSF cells; however, most of them slightly decreased the viability and inhibited proliferation of CRC cells. The N-acetylation or C-amidation of sialorphin or its alanine scan analogues resulted in decreased or abolished anti-proliferative activity of the NEP inhibitors towards the CRC cells. Additionally, thiorphan and sialorphin enhanced the anti-proliferative activity of other CRC-cell growth inhibitors (atrial natriuretic peptide-ANP and melphalan-MEL). The mechanisms involved in the anti-proliferative effects of the tested inhibitors were mediated via NEP and associated with induction of cell cycle arrest in the G0/G1 phase, increased activity of ERK1/2, and a reduced level of phosphorylation of mTOR (Ser2448), 4E-BP1, and p70S6K. However, the NEP inhibitors did not induce apoptosis in the CRC cells. These results have indicated that thiorphan and sialorphin or its derivatives AHNPR, QANPR, QHAPR, and QHNAR have the potential to be used as agents in treatment of patients with CRC.

May 2019 at a glance: epidemiology, drug effects on biomarkers, adverse events with LVAD.

May 2019 at a glance: epidemiology, drug effects on biomarkers, adverse events with LVAD.

2019 Focused Update of the Guidelines of the Taiwan Society of Cardiology for the Diagnosis and Treatment of Heart Failure.

Heart failure is a growing epidemic, especially in Taiwan because of the aging population. The 2016 Taiwan Society of Cardiology - Heart Failure with reduced Ejection Fraction (TSOC-HFrEF) registry showed that the guideline-recommended therapies were prescribed suboptimally both at the time of hospital discharge and during follow-up. We, therefore, conducted this 2019 focused update of the guidelines of the Taiwan Society of Cardiology for the diagnosis and treatment of heart failure to reinforce the importance of new diagnostic and therapeutic modalities of heart failure. The 2019 focused update discusses new diagnostic criteria, pharmacotherapy, non-pharmacological management, and certain co-morbidities of heart failure. Angiotensin receptor neprilysin inhibitor and If channel inhibitor is introduced as new and recommended medical therapies. Latest criteria of cardiac resynchronization therapy, implantable cardioverter-defibrillator, heart transplantation, and ventricular assist device therapy are reviewed in the non-pharmacological management chapter. Co-morbidities in heart failure are discussed including chronic kidney disease, diabetes, chronic obstructive pulmonary disease, and sleep-disordered breathing. We also explain the adequate use of oxygen therapy and non-invasive ventilation in heart failure management. A particular chapter for chemotherapy-induced cardiac toxicity is incorporated in the focused update to emphasize the importance of its recognition and management. Lastly, implications from the TSOC-HFrEF registry and post-acute care of heart failure are discussed to highlight the importance of guideline-directed medical therapy and the benefits of multidisciplinary disease management programs. With guideline recommendations, we hope that the management of heart failure can be improved in our society.

A REVIEW ON COMPARATIVE STUDY ON THE SAFETY AND EFFECTIVENESS OF SACUBITRIL-VALSARTAN COMBINATION WITH ACE/ARB THERAPY IN CARDIAC PATIENTS

Cardiovascular (CV) disease is a major cause of morbidity and mortality in the developing and the developed world, and represents a major barrier to sustainable human development. Ischemic heart disease, cerebrovascular disease, cardiomyopathy and heart failure (HF), and hypertension among others represent major forms of CV disease. Heart failure (HF) is among the key contributors to the CV-related health care burden, a uninterrupted concern despite the utilization of clinically tried guideline-directed therapies. The most common cause for HF is reduced left cavum heart muscle perform. ARBs produce equivalent mortality benefits with fewer adverse effects than ACE inhibitors. Angiotensin converting enzyme (ACEI) reduces the combined risk of death or hospitalization, slow progression of HF, and reduced rate of reinfarction. Sacubitril/valsartan could be a first-in-class twin action molecule of the neprilysin (NEP) substance sacubitril (AHU-377) and therefore the angiotensin II (Ang II) sort one (AT1) receptor blocker (ARB) valsartan. The beneficial antihypertensive and HF effects of sacubitril/valsartan are mediated through the inhibition of NEP in catabolizing the natriuretic peptides (NPs) and the blockade of Ang II, AT1 receptor with valsartan. These actions of sacubitril/ valsartan end in general dilation and inflated symptoms and symptoms, resulting in decrease in peripheral tube resistance and plasma volume contraction, all necessary actions for the lowering of BP and improving HF symptoms.&#x0D; Keywords: cardiovascular disease, left ventricular ejection fraction, angiotensin II receptor blocker, angiotensin converting enzyme, sacubitril/valsartan.

Regulation of Neprilysin Activity and Cognitive Functions in Rats After Prenatal Hypoxia.

The amyloid-degrading enzyme neprilysin (NEP) is one of the therapeutic targets in prevention and treatment of Alzheimer's disease (AD). As we have shown previously NEP expression in rat parietal cortex (Cx) and hippocampus (Hip) decreases with age and is also significantly reduced after prenatal hypoxia. Following the paradigms for enhancement of NEP expression and activity developed in cell culture, we analysed the efficacy of various compounds able to upregulate NEP using our model of prenatal hypoxia in rats. In addition to the previous data demonstrating that valproic acid can upregulate NEP expression both in neuroblastoma cells and in rat Cx and Hip we have further confirmed that caspase inhibitors can also restore NEP expression in rat Cx reduced after prenatal hypoxia. Here we also report that administration of a green tea catechin epigallocatechin-3-gallate (EGCG) to adult rats subjected to prenatal hypoxia increased NEP activity in blood plasma, Cx and Hip as well as improved memory performance in the 8-arm maze and novel object recognition tests. Moreover, EGCG administration led to an increased number of dendritic spines in the hippocampal CA1 area which correlated with memory enhancement. The data obtained allowed us to conclude that the decrease in the activity of the amyloid-degrading enzyme NEP, as well as a reduction in the number of labile interneuronal contacts in the hippocampus, contribute to early cognitive deficits caused by prenatal hypoxia and that there are therapeutic avenues to restore these deficits via NEP activation which could also be used for designing preventive strategies in AD.

C53: A novel particulate guanylyl cyclase B receptor activator that has sustained activity in vivo with anti-fibrotic actions in human cardiac and renal fibroblasts

The native particulate guanylyl cyclase B receptor (pGC-B) activator, C-type natriuretic peptide (CNP), induces anti-remodeling actions in the heart and kidney through the generation of the second messenger 3′, 5′ cyclic guanosine monophosphate (cGMP). Indeed fibrotic remodeling, particularly in cardiorenal disease states, contributes to disease progression and thus, has been a key target for drug discovery and development. Although the pGC-B/cGMP system has been perceived as a promising anti-fibrotic pathway, its therapeutic potential is limited due to the rapid degradation and catabolism of CNP by neprilysin (NEP) and natriuretic peptide clearance receptor (NPRC). The goal of this study was to bioengineer and test in vitro and in vivo a novel pGC-B activator, C53. Here we established that C53 selectively generates cGMP via the pGC-B receptor and is highly resistant to NEP and has less interaction with NPRC in vitro. Furthermore in vivo, C53 had enhanced cGMP-generating actions that paralleled elevated plasma CNP-like levels, thus indicating a longer circulating half-life compared to CNP. Importantly in human cardiac fibroblasts (HCFs) and renal fibroblasts (HRFs), C53 exerted robust cGMP-generating actions, inhibited TGFβ-1 stimulated HCFs and HRFs proliferation chronically and suppressed the differentiation of HCFs and HRFs to myofibroblasts. The current findings advance innovation in drug discovery and highlight C53 as a novel pGC-B activator with sustained in vivo activity and anti-fibrotic actions in vitro. Future studies are warranted to explore the efficacy and therapeutic opportunity of C53 targeting fibrosis in cardiorenal disease states and beyond.

Angiotensin converting enzyme inhibitors or angiotensin receptors blockers equally enhances skeletal structure via different metabolic influence

The impact of renin‐angiotensin system (RAS) on bone remodeling and metabolism has gained more interest in recent years, where several RAS metabolites are deemed as potential targets for skeletal diseases. This study compares the effects of angiotensin converting enzyme (ACE) inhibitors and angiotensin‐II (AngII) type‐1 receptor (AT1R) blockers on bone structure and remodeling and investigates the involvement of neutral endopeptidase enzyme (NEP) and angiotensin 1‐9 (Ang1‐9) in ovariectomized (OVX) rats. OVX animals received either captopril or losartan for 6 weeks. Both antihypertensive agents equally attenuated the elevated levels of bone metabolic bio‐markers and restored Ca2+ and phosphorous renal elimination and bone deposition. The altered bone cortical and trabecular morphometry in OVX rats was similarly ameliorated. In femurs heads, the expressions of NEP and Ang1‐9 were enhanced by captopril, while remained unchanged in losartan groups. In addition, both drugs down‐regulated the osteoclastogenesis inducing factor, receptor activator NF‐κB ligand (RANKL), while enhanced osteoprotegerin. Although, both antihypertensive agents had different influence on local skeletal RAS metabolism, losartan and captopril equally restored bone micro‐structure in estrogen deficient animals.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Localization of 99mTc-GRP Analogs in GRPR-Expressing Tumors: Effects of Peptide Length and Neprilysin Inhibition on Biological Responses.

The overexpression of gastrin-releasing peptide receptors (GRPRs) in frequently occurring human tumors has provided the opportunity to use bombesin (BBN) analogs as radionuclide carriers to cancer sites for diagnostic and therapeutic purposes. We have been alternatively exploring human GRP motifs of higher GRPR selectivity compared to frog BBN sequences aiming to improve pharmacokinetic profiles. In the present study, we compared two differently truncated human endogenous GRP motifs: GRP(14–27) and GRP(18–27). An acyclic tetraamine was coupled at the N-terminus to allow for stable binding of the SPECT radionuclide 99mTc. Their biological profiles were compared in PC-3 cells and in mice without or with coinjection of phosphoramidon (PA) to induce transient neprilysin (NEP) inhibition in vivo. The two 99mTc-N4-GRP(14/18–27) radioligands displayed similar biological behavior in mice. Coinjection of PA exerted a profound effect on in vivo stability and translated into notably improved radiolabel localization in PC-3 experimental tumors. Hence, this study has shown that promising 99mTc-radiotracers for SPECT imaging may indeed derive from human GRP sequences. Radiotracer bioavailability was found to be of major significance. It could be improved during in situ NEP inhibition resulting in drastically enhanced uptake in GRPR-expressing lesions.

Targeting amyloid clearance in Alzheimer's disease as a therapeutic strategy.

Targeting the amyloid-β (Aβ) peptide cascade has been at the heart of therapeutic developments in Alzheimer's disease (AD) research for more than 25years, yet no successful drugs have reached the marketplace based on this hypothesis. Nevertheless, the genetic and other evidence remains strong, if not overwhelming, that Aβ is central to the disease process. Most attention has focused on the biosynthesis of Aβ from its precursor protein through the successive actions of the β- and γ-secretases leading to the development of inhibitors of these membrane proteases. However, the levels of Aβ are maintained through a balance of its biosynthesis and clearance, which occurs both through further proteolysis by a family of amyloid-degrading enzymes (ADEs) and by a variety of transport processes. The development of late-onset AD appears to arise from a failure of these clearance mechanisms rather than by overproduction of the peptide. This review focuses on the nature of these clearance mechanisms, particularly the various proteases known to be involved, and their regulation and potential as therapeutic targets in AD drug development. The majority of the ADEs are zinc metalloproteases [e.g., the neprilysin (NEP) family, insulin-degrading enzyme, and angiotensin converting enzymes (ACE)]. Strategies for up-regulating the expression and activity of these enzymes, such as genetic, epigenetic, stem cell technology, and other pharmacological approaches, will be highlighted. Modifiable physiological mechanisms affecting the efficiency of Aβ clearance, including brain perfusion, obesity, diabetes, and sleep, will also be outlined. These new insights provide optimism for future therapeutic developments in AD research. LINKED ARTICLES: This article is part of a themed section on Therapeutics for Dementia and Alzheimer's Disease: New Directions for Precision Medicine. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.18/issuetoc.

Novel nonapeptide GLP (28-36) amide derivatives with improved hypoglycemic and body weight lowering effects.

Glucagon-like peptide-1 (GLP-1) has emerged as a major therapeutic target for the treatment of type 2 diabetes. The nonapeptide GLP-1 (28-36) amide is one of the biological C-terminal products of GLP-1 modified by the neutral endopeptidase (NEP) 24.11 with limited hypoglycemic activity. In this study, we focused on the modification of GLP-1 (28-36) amide for the first time and synthesized a series of GLP-1 (28-36) amide analogues. Results of biological activity evaluation in INS-1 cell, STZ-induced diabetic and diet induced obesity (DIO) mice indicated that S3 as a promising candidate to treat type 2 diabetes and obesity.