The novel Mas agonist, CGEN-856S, attenuates isoproterenol-induced cardiac remodeling and myocardial infarction injury in rats

Development of the cardioprotective drugs class based on pathophysiology of myocardial infarction: A comprehensive review

The cardiovascular system is mainly responsible for the transport of substances necessary to cellular metabolism. However, for the good performance of this function, there is need for adequate control of blood pressure levels of tissue perfusion and systemic arterial. Acute myocardial infarction is one of the complications of the cardiovascular system, that most affects the population around the world. This condition can be defined as a disease generated by an imbalance of oxygen concentrations used in cardiovascular metabolism, this change usually occurs because coronary occlusion, which prevents myocardial blood flow. The diagnosis is based on the set of clinical and laboratory investigations, which are in the release of cardiac enzyme biomarkers, cardiovascular and hemodynamic changes and cardiac accommodations. The treatment consists in the use of concomitant cardiovascular drugs, such as: antihypertensive, antiplatelet and hypolipidemic. Despite improvements in clinical and pharmacological management, acute myocardial infarction remains the leading cause of death worldwide. This finding encourages the scientific research of new drugs for the treatment of myocardial infarction or supporting therapies aimed at reducing the levels of deaths and comorbities generated by cardiovascular diseases.

The Mas agonist CGEN-856S prevents Ang II induced cardiomyocyte hypertrophy via nitric oxide production

With the previous knowledge of the cardioprotective effects of the Angiotensin-(1-7) axis, a agonist of Mas receptor has been described, the CGEN-856S. This peptide is more stable than Ang-(1-7), and has a low binding affinity to Angiotensin II receptors. Although the cardioprotective effects of CGEN-856S were previously shown in vivo, the mechanisms behind its effects are still unknown. Here, we employed a combination of molecular biology, confocal microscopy, and genetically modified mouse with Mas deletion to investigate the CGEN-856S protective signaling in cardiomyocytes. In isolated adult ventricular myocytes, CGEN-856S induced an increase in nitric oxide (NO) production which was absent in cells from Mas knockout mice. Using western blot, we observed a significant increase in phosphorylation of AKT after treatment with CGEN-856S. In addition, CGEN-856S prevented the Ang II induced hypertrophy and the nuclear translocation of GRK5 in a culture model of rat neonatal cardiomyocytes. Blockage of Mas receptor and inhibition of the NO synthase abolished the effects of CGEN-856S on Ang II treated cardiomyocytes. In conclusion, we show that CGEN-856S acting via receptor Mas induces NO raise to block Ang II induced cardiomyocyte hypertrophy. These results indicate that CGEN-856S acts very similarly to Ang-(1-7) in cardiac myocytes, highlighting its therapeutic potential for treating cardiovascular diseases.

Mas receptor: a potential strategy in the management of ischemic cardiovascular diseases

MasR is a critical element in the RAS accessory pathway that protects the heart against myocardial infarction, ischemia-reperfusion injury, and pathological remodeling by counteracting the effects of AT1R. This receptor is mainly stimulated by Ang 1-7, which is a bioactive metabolite of the angiotensin produced by ACE2. MasR activation attenuates ischemia-related myocardial damage by facilitating vasorelaxation, improving cell metabolism, reducing inflammation and oxidative stress, inhibiting thrombosis, and stabilizing atherosclerotic plaque. It also prevents pathological cardiac remodeling by suppressing hypertrophy- and fibrosis-inducing signals. In addition, the potential of MasR in lowering blood pressure, improving blood glucose and lipid profiles, and weight loss has made it effective in modulating risk factors for coronary artery disease including hypertension, diabetes, dyslipidemia, and obesity. Considering these properties, the administration of MasR agonists offers a promising approach to the prevention and treatment of ischemic heart disease.Abbreviations: Acetylcholine (Ach); AMP-activated protein kinase (AMPK); Angiotensin (Ang); Angiotensin receptor (ATR); Angiotensin receptor blocker (ARB); Angiotensin-converting enzyme (ACE); Angiotensin-converting enzyme inhibitor (ACEI); Anti-PRD1-BF1-RIZ1 homologous domain containing 16 (PRDM16); bradykinin (BK); Calcineurin (CaN); cAMP-response element binding protein (CREB); Catalase (CAT); C-C Motif Chemokine Ligand 2 (CCL2); Chloride channel 3 (CIC3); c-Jun N-terminal kinases (JNK); Cluster of differentiation 36 (CD36); Cocaine- and amphetamine-regulated transcript (CART); Connective tissue growth factor (CTGF); Coronary artery disease (CAD); Creatine phosphokinase (CPK); C-X-C motif chemokine ligand 10 (CXCL10); Cystic fibrosis transmembrane conductance regulator (CFTR); Endothelial nitric oxide synthase (eNOS); Extracellular signal-regulated kinase 1/2 (ERK 1/2); Fatty acid transport protein (FATP); Fibroblast growth factor 21 (FGF21); Forkhead box protein O1 (FoxO1); Glucokinase (Gk); Glucose transporter (GLUT); Glycogen synthase kinase 3β (GSK3β); High density lipoprotein (HDL); High sensitive C-reactive protein (hs-CRP); Inositol trisphosphate (IP3); Interleukin (IL); Ischemic heart disease (IHD); Janus kinase (JAK); Kruppel-like factor 4 (KLF4); Lactate dehydrogenase (LDH); Left ventricular end-diastolic pressure (LVEDP); Left ventricular end-systolic pressure (LVESP); Lipoprotein lipase (LPL); L-NG-Nitro arginine methyl ester (L-NAME); Low density lipoprotein (LDL); Mammalian target of rapamycin (mTOR); Mas-related G protein-coupled receptors (Mrgpr); Matrix metalloproteinase (MMP); MAPK phosphatase-1 (MKP-1); Mitogen-activated protein kinase (MAPK); Monocyte chemoattractant protein-1 (MCP-1); NADPH oxidase (NOX); Neuropeptide FF (NPFF); Neutral endopeptidase (NEP); Nitric oxide (NO); Nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB); Nuclear-factor of activated T-cells (NFAT); Pancreatic and duodenal homeobox 1 (Pdx1); Peroxisome proliferator- activated receptor γ (PPARγ); Phosphoinositide 3-kinases (PI3k); Phospholipase C (PLC); Prepro-orexin (PPO); Prolyl-endopeptidase (PEP); Prostacyclin (PGI2); Protein kinase B (Akt); Reactive oxygen species (ROS); Renin-angiotensin system (RAS); Rho-associated protein kinase (ROCK); Serum amyloid A (SAA); Signal transducer and activator of transcription (STAT); Sirtuin 1 (Sirt1); Slit guidance ligand 3 (Slit3); Smooth muscle 22α (SM22α); Sterol regulatory element-binding protein 1 (SREBP-1c); Stromal-derived factor-1a (SDF); Superoxide dismutase (SOD); Thiobarbituric acid reactive substances (TBARS); Tissue factor (TF); Toll-like receptor 4 (TLR4); Transforming growth factor β1 (TGF-β1); Tumor necrosis factor α (TNF-α); Uncoupling protein 1 (UCP1); Ventrolateral medulla (VLM).

Renin angiotensin aldosterone system in pulmonary fibrosis: Pathogenesis to therapeutic possibilities

Pulmonary fibrosis is a devastating lung disease with multifactorial etiology characterized by alveolar injury, fibroblast proliferation and excessive deposition of extracellular matrix proteins, which progressively results in respiratory failure and death. Accumulating evidence from experimental and clinical studies supports a central role of the renin angiotensin aldosterone system (RAAS) in the pathogenesis and progression of idiopathic pulmonary fibrosis. Angiotensin II (Ang II), a key vasoactive peptide of the RAAS mediates pro-inflammatory and pro-fibrotic effects on the lungs, adversely affecting organ function. Recent years have witnessed seminal discoveries in the field of RAAS. Identification of new enzymes, peptides and receptors has led to the development of several novel concepts. Of particular interest is the establishment of a protective axis of the RAAS comprising of Angiotensin converting enzyme 2 (ACE2), Angiotensin-(1-7) [Ang-(1-7)], and the Mas receptor (the ACE2/Ang-(1-7)/Mas axis), and the discovery of a functional role for the Angiotensin type 2 (AT₂) receptor. Herein, we will review our current understanding of the role of RAAS in lung fibrogenesis, provide evidence on the anti-fibrotic actions of the newly recognized RAAS components (the ACE2/Ang-(1-7)/Mas axis and AT₂ receptor), discuss potential strategies and translational efforts to convert this new knowledge into effective therapeutics for PF.

ACE2 and energy metabolism: the connection between COVID-19 and chronic metabolic disorders

The renin-angiotensin system (RAS) has currently attracted increasing attention due to its potential function in regulating energy homeostasis, other than the actions on cellular growth, blood pressure, fluid, and electrolyte balance. The existence of RAS is well established in metabolic organs, including pancreas, liver, skeletal muscle, and adipose tissue, where activation of angiotensin-converting enzyme (ACE) - angiotensin II pathway contributes to the impairment of insulin secretion, glucose transport, fat distribution, and adipokines production. However, the activation of angiotensin-converting enzyme 2 (ACE2) - angiotensin (1-7) pathway, a novel branch of the RAS, plays an opposite role in the ACE pathway, which could reverse these consequences by improving local microcirculation, inflammation, stress state, structure remolding, and insulin signaling pathway. In addition, new studies indicate the protective RAS arm possesses extraordinary ability to enhance brown adipose tissue (BAT) activity and induces browning of white adipose tissue, and consequently, it leads to increased energy expenditure in the form of heat instead of ATP synthesis. Interestingly, ACE2 is the receptor of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is threating public health worldwide. The main complications of SARS-CoV-2 infected death patients include many energy metabolism-related chronic diseases, such as diabetes. The specific mechanism leading to this phenomenon is largely unknown. Here, we summarize the latest pharmacological and genetic tools on regulating ACE/ACE2 balance and highlight the beneficial effects of the ACE2 pathway axis hyperactivity on glycolipid metabolism, as well as the thermogenic modulation.

Protective role of poly(lactic-co-glycolic) acid nanoparticle loaded with resveratrol against isoproterenol-induced myocardial infarction

Our study is aimed at evaluating the effects of pretreatment with Poly(lactic-co-glycolic) acid nanoparticle loaded with resveratrol (RSV PLGA NPs) compared to conventional resveratrol (RSV) on isoproterenol (ISO) induced myocardial infarction (MI) in rats. Sixty rats were randomly divided into six groups of 10 rats each. RSV and RSV PLGA NPs were given by gavage in two different doses (50 mg/kg body weight [BW] and 100 mg/kg BW) for 3 weeks. RSV and RSV PLGA NPs were given for 2 weeks starting 1 week before ISO administration. The blood samples were taken 24 hr after the last dose of ISO. The antioxidant, anti-inflammatory, and cardioprotective effects were evaluated in all groups. Only 100 mg/kg dose of RSV and both doses of RSV PLGA NPs offered a cardioprotective effect by preventing cardiac troponin T (cTnT) levels, lactate dehydrogenase (LDH), and aspartate aminotransferase (AST) activities leakage from cardiomyocytes, with the best result for RSV PLGA NPs. All the oxidative stress parameters were significantly improved after RSV PLGA NPs compared to RSV pretreatment. RSV PLGA NPs were more efficient than RSV in limiting the increase in inflammatory cytokine expressions such as tumor necrosis factor-alpha (TNF-α), interleukin 1 beta (IL-1β), and NF-kappaB (NF-kB) expression. In addition, RSV PLGA NPs significantly upregulated eNOS expression and downregulated iNOS expression. RSV PLGA NPs better prevented myocardial necrosis and reduced interstitial edema and neutrophil infiltration than RSV, on histopathological examination. Therefore, improving the bioactivity of RSV by nanotechnology may help limit cardiac injury after myocardial infarction.

Angiotensin-(1-7): Translational Avenues in Cardiovascular Control

Despite decades of research and numerous treatment approaches, hypertension and cardiovascular disease remain leading global public health problems. A major contributor to regulation of blood pressure, and the development of hypertension, is the renin-angiotensin system. Of particular concern, uncontrolled activation of angiotensin II contributes to hypertension and associated cardiovascular risk, with antihypertensive therapies currently available to block the formation and deleterious actions of this hormone. More recently, angiotensin-(1-7) has emerged as a biologically active intermediate of the vasodilatory arm of the renin-angiotensin system. This hormone antagonizes angiotensin II actions as well as offers antihypertensive, antihypertrophic, antiatherogenic, antiarrhythmogenic, antifibrotic and antithrombotic properties. Angiotensin-(1-7) elicits beneficial cardiovascular actions through mas G protein-coupled receptors, which are found in numerous tissues pivotal to control of blood pressure including the brain, heart, kidneys, and vasculature. Despite accumulating evidence for favorable effects of angiotensin-(1-7) in animal models, there is a paucity of clinical studies and pharmacokinetic limitations, thus limiting the development of therapeutic agents to better understand cardiovascular actions of this vasodilatory peptide hormone in humans. This review highlights current knowledge on the role of angiotensin-(1-7) in cardiovascular control, with an emphasis on significant animal, human, and therapeutic research efforts.

Novel Therapeutic Approaches Targeting the Renin-Angiotensin System and Associated Peptides in Hypertension and Heart Failure

Despite the success of renin-angiotensin system (RAS) blockade by angiotensin-converting enzyme (ACE) inhibitors and angiotensin II type 1 receptor (AT1R) blockers, current therapies for hypertension and related cardiovascular diseases are still inadequate. Identification of additional components of the RAS and associated vasoactive pathways, as well as new structural and functional insights into established targets, have led to novel therapeutic approaches with the potential to provide improved cardiovascular protection and better blood pressure control and/or reduced adverse side effects. The simultaneous modulation of several neurohumoral mediators in key interconnected blood pressure-regulating pathways has been an attractive approach to improve treatment efficacy, and several novel approaches involve combination therapy or dual-acting agents. In addition, increased understanding of the complexity of the RAS has led to novel approaches aimed at upregulating the ACE2/angiotensin-(1-7)/Mas axis to counter-regulate the harmful effects of the ACE/angiotensin II/angiotensin III/AT1R axis. These advances have opened new avenues for the development of novel drugs targeting the RAS to better treat hypertension and heart failure. Here we focus on new therapies in preclinical and early clinical stages of development, including novel small molecule inhibitors and receptor agonists/antagonists, less conventional strategies such as gene therapy to suppress angiotensinogen at the RNA level, recombinant ACE2 protein, and novel bispecific designer peptides.

New Molecules for Treating Resistant Hypertension: a Clinical Perspective

PURPOSE OF REVIEW

To review the findings of trials evaluating pharmacological treatment approaches for hypertension in general, and resistant hypertension (RH) in particular, and propose future research and clinical directions.

RECENT FINDINGS

RH is defined as blood pressure (BP) that remains above target levels despite adherence to at least three antihypertensive medications, including a diuretic. Thus far, clinical trials of pharmacological approaches in RH have focused on older molecules, with spironolactone being demonstrated as the most efficacious fourth-line agent. However, the use of spironolactone in clinical practice is hampered by its side effect profile and the risk of hyperkalaemia in important RH subgroups, such as patients with moderate-severe chronic kidney disease (CKD). Clinical trials of new molecules targeting both well-established and more recently elucidated pathophysiologic mechanisms of hypertension offer a multitude of potential treatment avenues that warrant further evaluation in the context of RH. These include selective mineralocorticoid receptor antagonists (MRAs), aldosterone synthase inhibitors (ASIs), activators of the counterregulatory renin-angiotensin-system (RAS), vaccines, neprilysin inhibitors alone and in combined formulations, natriuretic peptide receptor agonists A (NPRA-A) agonists, vasoactive intestinal peptide (VIP) agonists, centrally acting aminopeptidase A (APA|) inhibitors, antimicrobial suppression of central sympathetic outflow (minocycline), dopamine β-hydroxylase (DβH) inhibitors and Na+/H+ Exchanger 3 (NHE3) inhibitors. There is a paucity of data from trials evaluating newer molecules for the treatment of RH. Emergent novel molecules for non-resistant forms of hypertension heighten the prospects of identifying new, effective and well-tolerated pharmacological approaches to RH. There is a glaring need to undertake RH-focused trials evaluating their efficacy and clinical applicability.

Participation of Gαi-Adenylate Cyclase and ERK1/2 in Mas Receptor Signaling Pathways

The MasR receptor (MasR) is an orphan G protein-coupled receptor proposed as a candidate for mediating the angiotensin (Ang)-converting enzyme 2-Ang-(1–7) protective axis of renin-angiotensin system. This receptor has been suggested to participate in several physiological processes including cardio- and reno-protection and regulation of the central nervous system function. Although the knowledge of the signaling mechanisms associated with MasR is essential for therapeutic purposes, these are still poorly understood. Accordingly, in the current study we aimed to characterize the signaling pathways triggered by the MasR. To do that, we measured cAMP and Ca²⁺ levels in both naïve and MasR transfected cells in basal conditions and upon incubation with putative MasR ligands. Besides, we evaluated activation of ERK1/2 by Ang-(1–7) in MasR transfected cells. Results indicated the existence of a high degree of MasR constitutive activity toward cAMP modulation. This effect was not mediated by the PDZ-binding motif of the MasR but by receptor coupling to Gαi-adenylyl cyclase signaling pathway. Incubation of MasR transfected cells with Ang-(1–7) or the synthetic ligand AVE 0991 amplified MasR negative modulation of cAMP levels. On the other hand, we provided evidence for lack of MasR-associated modulation of Ca²⁺ levels by Ang-(1–7). Finally, it was determined that the MasR attenuated Ang-(1–7)-induced ERK1/2 phosphorylation mediated by AT1R. We provided further characterization of MasR signaling mechanisms regarding its constitutive activity and response to putative ligands. This information could prove useful to better describe MasR physiological role and development of therapeutic agents that could modulate its action.

Novel Medical Treatments for Hypertension and Related Comorbidities

Purpose of Review

The purpose of this review is to summarize the most recent data available on advances in development of novel medical treatments for hypertension and related comorbidities.

Recent Findings

Approximately half of all hypertensive patients have not achieved goal blood pressure with current available antihypertensive medications. Recent landmark studies and new hypertension guidelines have called for stricter blood pressure control, creating a need for better strategies for lowering blood pressure. This has led to a shift in focus, in recent years, to the development of combination pills as a means of achieving improved blood pressure control by increasing adherence to prescribed medications along with further research and development of promising novel drugs based on discovery of new molecular targets such as the counter-regulatory renin-angiotensin system.

Summary

Fixed-dose combination pills and novel treatments based on recently discovered pathogenic mechanisms of hypertension that have demonstrated promising results as treatments for hypertension and related comorbidities will be discussed in this review.

Angiotensin-(1-7) and Alamandine on Experimental Models of Hypertension and Atherosclerosis

PURPOSE OF REVIEW

The purpose of this review was to summarize the current knowledge on the role of angiotensin-(1-7) [Ang-(1-7)] and alamandine in experimental hypertension and atherosclerosis.

RECENT FINDINGS

The renin-angiotensin system (RAS) is a very complex system, composed of a cascade of enzymes, peptides, and receptors, known to be involved in the pathogenesis of hypertension and atherosclerosis. Ang-(1-7), identified and characterized in 1987, and alamandine, discovered 16 years after, are the newest two main effector molecules from the RAS, protecting the vascular system against hypertension and atherosclerosis. While the beneficial effects of Ang-(1-7) have been widely studied in several experimental models of hypertension, much less studies were performed in experimental models of atherosclerosis. Alamandine has shown similar vascular effects to Ang-(1-7), namely, endothelial-dependent vasorelaxation mediated by nitric oxide and hypotensive effects in experimental hypertension. There are few studies on the effects of alamandine on atherosclerosis.

Molecular remodeling of the renin-angiotensin system after kidney transplantation

Objective:

We aimed at assessing the molecular adaptation of the renin-angiotensin system (RAS) after successful kidney transplantation (KTX).

Materials and methods:

In this prospective, exploratory study we analyzed 12 hemodialysis (HD) patients, who received a KTX and had excellent graft function six to 12 months thereafter. The concentrations of plasma Angiotensin (Ang) peptides (Ang I, Ang II, Ang-(1–7), Ang-(1–5), Ang-(2–8), Ang-(3–8)) were simultaneously quantified with a novel mass spectrometry-based method. Further, renin and aldosterone concentrations were determined by standard immunoassays.

Results:

Ang values showed a strong inter-individual variability among HD patients. Yet, despite a continued broad dispersion of Ang values after KTX, a substantial improvement of the renin/Ang II correlation was observed in patients without RAS blockade or on angiotensin receptor blocker (HD: renin/Ang II R² = 0.660, KTX: renin/Ang II R² = 0.918). Ang-(1–7) representing the alternative RAS axis was only marginally detectable both on HD and after KTX.

Conclusions:

Following KTX, renin-dependent Ang II formation adapts in non-ACE inhibitor-treated patients. Thus, a largely normal RAS regulation is reconstituted after successful KTX. However, individual Ang concentration variations and a lack of potentially beneficial alternative peptides after KTX call for individualized treatment. The long-term post-transplant RAS regulation remains to be determined.

The ACE2/Angiotensin-(1-7)/MAS Axis of the Renin-Angiotensin System: Focus on Angiotensin-(1-7)

The renin-angiotensin system (RAS) is a key player in the control of the cardiovascular system and hydroelectrolyte balance, with an influence on organs and functions throughout the body. The classical view of this system saw it as a sequence of many enzymatic steps that culminate in the production of a single biologically active metabolite, the octapeptide angiotensin (ANG) II, by the angiotensin converting enzyme (ACE). The past two decades have revealed new functions for some of the intermediate products, beyond their roles as substrates along the classical route. They may be processed in alternative ways by enzymes such as the ACE homolog ACE2. One effect is to establish a second axis through ACE2/ANG-(1-7)/MAS, whose end point is the metabolite ANG-(1-7). ACE2 and other enzymes can form ANG-(1-7) directly or indirectly from either the decapeptide ANG I or from ANG II. In many cases, this second axis appears to counteract or modulate the effects of the classical axis. ANG-(1-7) itself acts on the receptor MAS to influence a range of mechanisms in the heart, kidney, brain, and other tissues. This review highlights the current knowledge about the roles of ANG-(1-7) in physiology and disease, with particular emphasis on the brain.

Significance of angiotensin 1-7 coupling with MAS1 receptor and other GPCRs to the renin-angiotensin system: IUPHAR Review 22

Angiotensins are a group of hormonal peptides and include angiotensin II and angiotensin 1-7 produced by the renin angiotensin system. The biology, pharmacology and biochemistry of the receptors for angiotensins were extensively reviewed recently. In the review, the receptor nomenclature committee was not emphatic on designating MAS1 as the angiotensin 1-7 receptor on the basis of lack of classical G protein signalling and desensitization in response to angiotensin 1-7, as well as a lack of consensus on confirmatory ligand pharmacological analyses. A review of recent publications (2013-2016) on the rapidly progressing research on angiotensin 1-7 revealed that MAS1 and two additional receptors can function as 'angiotensin 1-7 receptors', and this deserves further consideration. In this review we have summarized the information on angiotensin 1-7 receptors and their crosstalk with classical angiotensin II receptors in the context of the functions of the renin angiotensin system. It was concluded that the receptors for angiotensin II and angiotensin 1-7 make up a sophisticated cross-regulated signalling network that modulates the endogenous protective and pathogenic facets of the renin angiotensin system.

New agents modulating the renin-angiotensin-aldosterone system-Will there be a new therapeutic option?

The renin-angiotensin-aldosterone system (RAAS) is more complex than it was originally regarded. According to the current subject knowledge, there are two main axes of the RAAS: (1) angiotensin-converting enzyme (ACE)-angiotensin II-AT₁ receptor axis and (2) ACE2-angiotensin-(1-7)-Mas receptor axis. The activation of the first axis leads to deleterious effects, including vasoconstriction, endothelial dysfunction, thrombosis, inflammation, and fibrosis; therefore, blocking the components of this axis is a highly rational and commonly used therapeutic procedure. The ACE2-Ang-(1-7)-Mas receptor axis has a different role, since it often opposes the effects induced by the classical ACE-Ang II-AT₁ axis. Once the positive effects of the ACE2-Ang-(1-7)-Mas axis were discovered, the alternative ways of pharmacotherapy activating this axis of RAAS appeared. This article briefly describes new molecules affecting the RAAS, namely: recombinant human ACE2, ACE2 activators, angiotensin-(1-7) peptide and non-peptide analogs, aldosterone synthase inhibitors, and the third and fourth generation of mineralocorticoid receptor antagonists. The results of the experimental and clinical studies are encouraging, which leads us to believe that these new molecules can support the treatment of cardiovascular diseases as well as cardiometabolic disorders.

Transgenic overexpression of transient receptor potential vanilloid subtype 1 attenuates isoproterenol-induced myocardial fibrosis in mice

Transient receptor potential vanilloid subtype 1 (TRPV1) is a non-selective cation channel with high permeability to Ca2+. Intracellular Ca2+ signaling is an essential regulator of endothelial nitric oxide (NO) synthase (eNOS) that plays a beneficial role in myocardial fibrosis. The aim of the present study was to determine the role of TRPV1 in isoproterenol-induced myocardial fibrosis. Transgenic mice overexpressing TRPV1 were generated on a C57BL/6J genetic background. An animal model of myocardial fibrosis was created by subcutaneously injecting the mice with isoproterenol. We found that the wild-type mice exhibited a significant increase in heart/body weight ratio, left ventricle/body weight ratio, left ventricular end-diastolic pressure (LVEDP), the cardiac fibrotic lesion area and collagen content, as well as a marked decrease in eNOS phosphorylation and NO/cyclic guanosine monophosphate (cGMP) levels at 2 weeks after the administration of isoproterenol (all p<0.01). However, these changes were significantly attenuated in the TRPV1 transgenic mice (p<0.05 or p<0.01). Moreover, the beneficial effects on myocardial fibrosis exerted by the overexpression of TRPV1 were attenuated by the administration of the eNOS inhibitor, Nω-nitro-L-arginine methyl ester (L-NAME) (all p<0.05). Similar anti-fibrotic effects were observed in in vitro experiments with primary cultured cardiac fibroblasts. The findings of our study suggest that TRPV1 overexpression attenuates isoproterenol‑induced myocardial fibrosis.

ACE inhibition, ACE2 and angiotensin-(1-7) axis in kidney and cardiac inflammation and fibrosis

The Renin Angiotensin System (RAS) is a pivotal physiological regulator of heart and kidney homeostasis, but also plays an important role in the pathophysiology of heart and kidney diseases. Recently, new components of the RAS have been discovered, including angiotensin converting enzyme 2 (ACE2), Angiotensin(Ang)-(1-7), Mas receptor, Ang-(1-9) and Alamandine. These new components of RAS are formed by the hydrolysis of Ang I and Ang II and, in general, counteract the effects of Ang II. In experimental models of heart and renal diseases, Ang-(1-7), Ang-(1-9) and Alamandine produced vasodilation, inhibition of cell growth, anti-thrombotic, anti-inflammatory and anti-fibrotic effects. Recent pharmacological strategies have been proposed to potentiate the effects or to enhance the formation of Ang-(1-7) and Ang-(1-9), including ACE2 activators, Ang-(1-7) in hydroxypropyl β-cyclodextrin, cyclized form of Ang-(1-7) and nonpeptide synthetic Mas receptor agonists. Here, we review the role and effects of ACE2, ACE2 activators, Ang-(1-7) and synthetic Mas receptor agonists in the control of inflammation and fibrosis in cardiovascular and renal diseases and as counter-regulators of the ACE-Ang II-AT1 axis. We briefly comment on the therapeutic potential of the novel members of RAS, Ang-(1-9) and alamandine, and the interactions between classical RAS inhibitors and new players in heart and kidney diseases.

Extracellular Ubiquitin: Role in Myocyte Apoptosis and Myocardial Remodeling

Ubiquitin (UB) is a highly conserved low molecular weight (8.5 kDa) protein. It consists of 76 amino acid residues and is found in all eukaryotic cells. The covalent linkage of UB to a variety of cellular proteins (ubiquitination) is one of the most common posttranslational modifications in eukaryotic cells. This modification generally regulates protein turnover and protects the cells from damaged or misfolded proteins. The polyubiquitination of proteins serves as a signal for degradation via the 26S proteasome pathway. UB is present in trace amounts in body fluids. Elevated levels of UB are described in the serum or plasma of patients under a variety of conditions. Extracellular UB is proposed to have pleiotropic roles including regulation of immune response, anti-inflammatory, and neuroprotective activities. CXCR4 is identified as receptor for extracellular UB in hematopoietic cells. Heart failure represents a major cause of morbidity and mortality in western society. Cardiac remodeling is a determinant of the clinical course of heart failure. The components involved in myocardial remodeling include-myocytes, fibroblasts, interstitium, and coronary vasculature. Increased sympathetic nerve activity in the form of norepinephrine is a common feature during heart failure. Acting via β-adrenergic receptor (β-AR), norepinephrine is shown to induce myocyte apoptosis and myocardial fibrosis. β-AR stimulation increases extracellular levels of UB in myocytes, and UB inhibits β-AR-stimulated increases in myocyte apoptosis and myocardial fibrosis. This review summarizes intracellular and extracellular functions of UB with particular emphasis on the role of extracellular UB in cardiac myocyte apoptosis and myocardial remodeling.

MAS and its related G protein-coupled receptors, Mrgprs

The Mas-related G protein-coupled receptors (Mrgprs or Mas-related genes) comprise a subfamily of receptors named after the first discovered member, Mas. For most Mrgprs, pruriception seems to be the major function based on the following observations: 1) they are relatively promiscuous in their ligand specificity with best affinities for itch-inducing substances; 2) they are expressed in sensory neurons and mast cells in the skin, the main cellular components of pruriception; and 3) they appear in evolution first in tetrapods, which have arms and legs necessary for scratching to remove parasites or other noxious substances from the skin before they create harm. Because parasites coevolved with hosts, each species faced different parasitic challenges, which may explain another striking observation, the multiple independent duplication and expansion events of Mrgpr genes in different species as a consequence of parallel adaptive evolution. Their predominant expression in dorsal root ganglia anticipates additional functions of Mrgprs in nociception. Some Mrgprs have endogenous ligands, such as β-alanine, alamandine, adenine, RF-amide peptides, or salusin-β. However, because the functions of these agonists are still elusive, the physiologic role of the respective Mrgprs needs to be clarified. The best studied Mrgpr is Mas itself. It was shown to be a receptor for angiotensin-1-7 and to exert mainly protective actions in cardiovascular and metabolic diseases. This review summarizes the current knowledge about Mrgprs, their evolution, their ligands, their possible physiologic functions, and their therapeutic potential.

International Union of Basic and Clinical Pharmacology. XCIX. Angiotensin Receptors: Interpreters of Pathophysiological Angiotensinergic Stimuli [corrected]

The renin angiotensin system (RAS) produced hormone peptides regulate many vital body functions. Dysfunctional signaling by receptors for RAS peptides leads to pathologic states. Nearly half of humanity today would likely benefit from modern drugs targeting these receptors. The receptors for RAS peptides consist of three G-protein-coupled receptors—the angiotensin II type 1 receptor (AT1 receptor), the angiotensin II type 2 receptor (AT2 receptor), the MAS receptor—and a type II trans-membrane zinc protein—the candidate angiotensin IV receptor (AngIV binding site). The prorenin receptor is a relatively new contender for consideration, but is not included here because the role of prorenin receptor as an independent endocrine mediator is presently unclear. The full spectrum of biologic characteristics of these receptors is still evolving, but there is evidence establishing unique roles of each receptor in cardiovascular, hemodynamic, neurologic, renal, and endothelial functions, as well as in cell proliferation, survival, matrix-cell interaction, and inflammation. Therapeutic agents targeted to these receptors are either in active use in clinical intervention of major common diseases or under evaluation for repurposing in many other disorders. Broad-spectrum influence these receptors produce in complex pathophysiological context in our body highlights their role as precise interpreters of distinctive angiotensinergic peptide cues. This review article summarizes findings published in the last 15 years on the structure, pharmacology, signaling, physiology, and disease states related to angiotensin receptors. We also discuss the challenges the pharmacologist presently faces in formally accepting newer members as established angiotensin receptors and emphasize necessary future developments.

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

New Approaches in the Treatment of Hypertension

Hypertension is the most common modifiable risk factor for cardiovascular disease and death, and lowering blood pressure with antihypertensive drugs reduces target organ damage and prevents cardiovascular disease outcomes. Despite a plethora of available treatment options, a substantial portion of the hypertensive population has uncontrolled blood pressure. The unmet need of controlling blood pressure in this population may be addressed, in part, by developing new drugs and devices/procedures to treat hypertension and its comorbidities. In this Compendium Review, we discuss new drugs and interventional treatments that are undergoing preclinical or clinical testing for hypertension treatment. New drug classes, eg, inhibitors of vasopeptidases, aldosterone synthase and soluble epoxide hydrolase, agonists of natriuretic peptide A and vasoactive intestinal peptide receptor 2, and a novel mineralocorticoid receptor antagonist are in phase II/III of development, while inhibitors of aminopeptidase A, dopamine β-hydroxylase, and the intestinal Na + /H + exchanger 3, agonists of components of the angiotensin-converting enzyme 2/angiotensin(1–7)/Mas receptor axis and vaccines directed toward angiotensin II and its type 1 receptor are in phase I or preclinical development. The two main interventional approaches, transcatheter renal denervation and baroreflex activation therapy, are used in clinical practice for severe treatment resistant hypertension in some countries. Renal denervation is also being evaluated for treatment of various comorbidities, eg, chronic heart failure, cardiac arrhythmias and chronic renal failure. Novel interventional approaches in early development include carotid body ablation and arteriovenous fistula placement. Importantly, none of these novel drug or device treatments has been shown to prevent cardiovascular disease outcomes or death in hypertensive patients.

Deletion of soluble epoxide hydrolase attenuates cardiac hypertrophy via down-regulation of cardiac fibroblasts-derived fibroblast growth factor-2

OBJECTIVE

Inhibition of soluble epoxide hydrolase (Ephx2) has been shown to play a protective role in cardiac hypertrophy, but the mechanism is not fully understood. We tested the hypothesis that deletion of soluble epoxide hydrolase attenuates cardiac hypertrophy via down-regulation of cardiac fibroblasts-derived fibroblast growth factor-2.

DESIGN

Prospective, controlled, and randomized animal study.

SETTING

University laboratory.

SUBJECTS

Male wild-type C57BL/6 mice and Ephx2 (-/-) mice.

INTERVENTIONS

Male wild-type or Ephx2 (-/-) mice were subjected to transverse aorta constriction surgery.

MEASUREMENTS AND MAIN RESULTS

Four weeks after transverse aorta constriction, Ephx2 (-/-) mice did not develop significant cardiac hypertrophy as that of wild-type mice, indicated by no changes in the ratio of heart weight/body weight and ventricular wall thickness after transverse aorta constriction. Cardiac fibroblast growth factor-2 increased in wild-type-transverse aorta constriction group but this did not change in Ephx2 (-/-)-transverse aorta constriction group, and the serum level of fibroblast growth factor-2 did not change in both groups. In vitro, cardiac fibroblasts were stimulated by angiotensin II to analyze the expression of fibroblast growth factor-2. The effect of increased fibroblast growth factor-2 from cardiac fibroblasts induced by angiotensin II was attenuated by soluble epoxide hydrolase deletion. ERK1/2, p38, and AKT kinase were involved in fibroblast growth factor-2 expression regulated by angiotensin II, and soluble epoxide hydrolase deletion lowered the phosphorylation of ERK1/2 not p38 or AKT to mediate fibroblast growth factor-2 expression. In addition, soluble epoxide hydrolase deletion did not attenuate cardiomyocytes hypertrophy induced by exogenous fibroblast growth factor-2.

CONCLUSIONS

Our present data demonstrated that deletion of soluble epoxide hydrolase prevented cardiac hypertrophy not only directly to cardiomyocytes but also to cardiac fibroblasts by reducing expression of fibroblast growth factor-2.

Chlorogenic acid prevents isoproterenol-induced hypertrophy in neonatal rat myocytes

Cardiac hypertrophy is an independent risk factor for cardiovascular disease and its subsequent progression to heart failure represents a major cause of morbidity and mortality in the world. CGA is an important component of Chinese herbal medicine, acting as an antioxidant, scavenging free radicals and preventing inflammation. This study found that with the pre-treatment of chlorogenic acid in Iso-induced neonatal rat myocytes, the levels of the hypertrophic markers, ANP, BNP and β-MHC decreased. The nuclear translocation of NF-κB was blocked, whereas NF-κBIA, an inhibitor of NF-κB, was upregulated accordingly. And the level of the intracellular ROS was also reduced. These data reveal that chlorogenic acid may inhibit Iso-induced cardiac hypertrophy by attenuating NF-κB signaling pathway and suppressing ROS.

Klotho suppresses cardiomyocyte apoptosis in mice with stress-induced cardiac injury via downregulation of endoplasmic reticulum stress

Cardiomyocyte apoptosis is a common pathological alteration in heart disease which results in systolic dysfunction or sudden death. Klotho is a novel anti-aging hormone. We tested the effects of klotho on cell apoptosis in isoproterenol-treated cardiomyocytes. In BALB/c mice, cardiac injury was induced by subcutaneous injection of isoproterenol (5 mg/kg, for 9 days, s.c.). Klotho (0.01 mg/kg, every other day for 4 days, i.p.) was administered to determine the changes in isoproterenol-induced apoptosis. Mouse heart was harvested at day 2, day 5, and day 9 after isoproterenol injection. Isoproterenol induced cardiac apoptosis and endoplasmic reticulum (ER) stress in a time-dependent manner. However, klotho partly reversed isoproterenol-induced cardiac apoptosis and ER stress. These same effects were observed in cultured cardiomyocytes. Furthermore, the results also showed that SB203580, a p38 inhibitor, and SP600125, a c-Jun NH2-terminal kinase (JNK) inhibitor, reduced cardiomyocyte apoptosis and ER stress, however, klotho suppressed isoproterenol-induced activation of p38 and JNK. Taken together, these results indicated that cardioprotection by klotho was related to the attenuation of ER stress and ER stress-induced apoptosis, at least partly, through suppressing activation of the p38 and JNK pathway.