Targeting the renin-angiotensin-aldosterone system in heart failure

Mechanisms of action and adaptive responses to diclofenac and meloxicam during the early life stages of Oryzias melastigma

Non-steroidal anti-inflammatory drugs (NSAIDs), though designed to target specific molecular pathways, pose significant environmental risks to non-target organisms, particularly marine fish. This study investigated the toxicity mechanisms and adaptive responses to diclofenac (DCF) and meloxicam (MEX) during the early life stages (ELS) of Oryzias melastigma at environmentally relevant concentrations over a 31-day period. Mechanistic investigations of sub-lethal effects were conducted using Enzyme-Linked Immunosorbent Assay (ELISA), RNA sequencing (RNA-Seq) and quantitative PCR (qPCR). The results revealed that cyclooxygenase (COX) inhibition disrupted the renin-angiotensin system, leading to an accumulation of angiotensin II and cardiovascular developmental defects. Additionally, downregulation of the pla2 gene reduced substrates essential for COX enzyme activity, exacerbating the effects. Although NSAIDs are known to affect the digestive system, no significant effects on developmental factors were observed. RNA-Seq and qPCR analyses revealed an adaptive upregulation of key genes, including ace2 and cyp7a1, involved in cardiovascular and metabolic regulation. Furthermore, 16S rRNA sequencing identified shifts in the microbial community, particularly in g_Rubritalea and g_Sphingomonas genera. Both the upregulated genes and the altered microbial taxa likely played a role in mitigating toxic effects and promoting homeostasis. Moreover, molecular docking suggested that MEX exhibited stronger sub-lethal effects than DCF, likely due to its higher binding affinity to COX. These findings provide valuable insights into NSAID toxicity mechanisms in marine fish, highlighting the importance of adaptive responses in countering environmental stress and underscoring the long-term ecological risks of chronic NSAID exposure.

Angiotensin IV does not exert prothrombotic effects in vivo

Thrombosis and thromboembolism are serious clinical complications of cardiovascular diseases and are among the leading causes of mortality worldwide. Dysregulation of the renin-angiotensin system is associated with an increased incidence of thrombotic events. Angiotensin II (AngII) is known to enhance platelet aggregation, contributing to a prothrombotic state in patients. Important biological roles of other angiotensin peptides and their receptors have been shown, but their specific role in thrombus formation remains unclear. Recent evidence suggests a prothrombotic role of angiotensin IV (AngIV). To confirm the prothrombotic effects of AngIV and to further investigate AngIV-mediated mechanisms, we utilized osmotic minipumps to administer AngIV in mice continuously over 4 weeks. AngIV treatment did not induce thrombus formation in the heart, did not affect platelet numbers, and did not enhance platelet aggregation. HGF, c-MET, or PAI-1 expression levels in the heart were not affected by AngIV treatment in mice. Furthermore, we did not observe altered platelet aggregation of human platelets incubated with HGF. These findings indicate that AngIV does not regulate key prothrombotic mechanisms.

Effects of Sacubitril/Valsartan on cardiac function, blood biochemistry and clinical efficacy in early ventricular remodeling after acute myocardial infarction

Ventricular remodeling (VR) after acute ST-elevation myocardial infarction (STEMI) is an important predictor for medium- and long-term prognosis. This study focuses on the relevant indexes of VR in patients with AMI, in which, the intervention effects of sacubitril/valsartan and enalapril were compared, guiding the clinical treatment. 58 patients with acute STEMI treated with PCI were divided into research group and control group. UCG was performed at 1 week, 1 month and 3 months after MI, and the patients' indexes were collected to compare VR and adverse reactions in the two groups. The test results showed that there was no statistical difference in the baseline data of patients in the two groups, which were comparable. In the blood biochemical index examination, no statistical difference was found in cTnI and NT-proBNP between the two groups. At 1 week after operation, the levels of cTnI and NT-proBNP in research group were lower than those in the control group. In ECG examination, there was no statistical significance in the levels of LVEF, LVEDD and LVESD at admission between the two groups. After 1 week, the results of LVEF, LVEDD, LVESD in the research group were higher than those in the control group. The results of this study show that sacubitril/valsartan can be used in patients with AMI instead of enalapril. Sacubitril/valsartan improves cardiac function in patients with emergency percutaneous coronary intervention (PCI) for AMI, inhibits ventricular remodeling, and has a low incidence of adverse cardiac events and adverse drug reactions.

ACE2 activation alleviates sepsis-induced cardiomyopathy by promoting MasR-Sirt1-mediated mitochondrial biogenesis

Sepsis-induced cardiomyopathy (SIC), caused by a dysregulated host response to infection, is a major contributor to high mortality. Angiotensin-converting enzyme 2 (ACE2), a crucial component of the renin-angiotensin system (RAS), has protective effects against several cardiovascular diseases, such as myocardial infarction and heart failure. However, the role of ACE2 in the pathogenesis of SIC and underlying mechanisms remain unknown. The present study was designed to examine the effects of ACE2 activation or inhibition on SIC in C57BL/6 mice. The ACE2 activator diminazene aceturate (DIZE) and ACE2 inhibitor MLN-4760 were applied for treatment. Myocardial function, inflammatory response, oxidative stress, apoptosis and mitochondrial biogenesis were investigated. Major assays were echocardiography, H&E staining, immunofluorescence staining, DHE staining, TUNEL staining, Western blot, qPCR analysis, ELISA and corresponding kits. We confirmed that ACE2 was markedly downregulated in septic heart tissues. Pharmacological activation of ACE2 by DIZE ameliorated cecal ligation puncture (CLP)-induced mortality, cardiac dysfunction, inflammatory response, oxidative stress and the cardiomyocyte apoptosis by promoting MasR-Sirt1-mediated mitochondrial biogenesis. In contrast, SIC was aggravated via inhibiting MasR-Sirt1-mediated mitochondrial biogenesis by the use of ACE2 inhibitor MLN-4760. Consequently, activation of ACE2 may protect against SIC by promoting MasR-Sirt1-mediated mitochondrial biogenesis.

Neuroendocrine hormone status and diuretic response to atrial natriuretic peptide in patients with acute heart failure

AIMS

Given the various effects of sacubitril/valsartan in heart failure, a deeper understanding of atrial natriuretic peptide (ANP) actions is warranted. Natriuresis is a fundamental action of ANP in acute heart failure (AHF), whereas the diuretic effect of ANP is different in each patient according to the diversity of renal response to ANP, which is affected by baseline plasma ANP status and deficiency of circulating ANP. Meanwhile, associations between other neuroendocrine hormones and the diuretic response to ANP are unclear. This study investigated the impact of pivotal neuroendocrine hormones on the diuretic effects of exogenous ANP, carperitide.

METHODS AND RESULTS

Plasma ANP, renin, aldosterone, and vasopressin levels and the diuretic effect of 0.0125 μg/kg/min of carperitide alone for the first 6 h were prospectively evaluated in 75 patients with AHF. Lower ANP levels were significantly associated with a greater diuretic response to exogenous ANP (r = -0.35, P = 0.002). Additionally, higher vasopressin levels were significantly related to the poor diuretic effects of exogenous ANP (r = -0.54, P < 0.001). Plasma ANP and vasopressin concentrations were not significantly correlated (r = 0.19, P = 0.10). Baseline systolic blood pressure, renal function, and prior use of loop diuretics did not predict the diuretic response to exogenous ANP, whereas vasopressin levels independently predicted a diuretic response to exogenous ANP (P < 0.001), as well as lower plasma ANP levels (P = 0.027).

CONCLUSIONS

Vasopressin status was significantly associated with the diuretic response to exogenous ANP in AHF, independent of plasma ANP status. The results may provide a better understanding of the actions of sacubitril/valsartan.

Sustained-Release Ivabradine Hemisulfate in Patients With Systolic Heart Failure

BACKGROUND

Ivabradine has potent actions in reducing heart rate and improving clinical outcomes of chronic heart failure with reduced ejection fraction (HFrEF). At present, only the short-acting formulation of ivabradine is available that needs to be administered twice daily.

OBJECTIVES

This study sought to evaluate the role of ivabradine hemisulfate sustained release (SR), a novel long-acting formulation of ivabradine dosed once daily, in stable patients with HFrEF.

METHODS

Patients with stabilized HFrEF in New York Heart Association functional class II-IV were enrolled and randomized to receive placebo or ivabradine SR in addition to standard medications. The primary endpoint was the change of left ventricular (LV) end-systolic volume index from baseline to week 32.

RESULTS

We randomly assigned 181 patients to placebo and 179 patients to ivabradine SR. After 32 weeks, a significant improvement of LV end-systolic volume index from baseline was observed in both arms with a greater effect in the ivabradine SR arm. Ivabradine SR therapy also exhibited superiority in improving LV end-diastolic volume index, LV ejection fraction, resting heart rate, the Kansas City Cardiomyopathy Questionnaire score, and hospital admission for heart failure worsening and cardiovascular disease in comparison to placebo. Overall adverse events showed no difference between the treatment arms. There were fewer occurrences of worsening heart failure in the ivabradine SR arm.

CONCLUSIONS

The present study demonstrates that ivabradine SR once daily in addition to optimum standard therapy improved heart function in patients with HFrEF. (Clinical Trial of Systolic Heart Failure Treatment of IvabRadine Hemisulfate Sustained-release Tablets [FIRST]; NCT02188082).

Update on New Aspects of the Renin-Angiotensin System in Hepatic Fibrosis and Portal Hypertension: Implications for Novel Therapeutic Options

There is considerable experimental evidence that the renin angiotensin system (RAS) plays a central role in both hepatic fibrogenesis and portal hypertension. Angiotensin converting enzyme (ACE), a key enzyme of the classical RAS, converts angiotensin I (Ang I) to angiotensin II (Ang II), which acts via the Ang II type 1 receptor (AT1R) to stimulate hepatic fibrosis and increase intrahepatic vascular tone and portal pressure. Inhibitors of the classical RAS, drugs which are widely used in clinical practice in patients with hypertension, have been shown to inhibit liver fibrosis in animal models but their efficacy in human liver disease is yet to be tested in adequately powered clinical trials. Small trials in cirrhotic patients have demonstrated that these drugs may lower portal pressure but produce off-target complications such as systemic hypotension and renal failure. More recently, the alternate RAS, comprising its key enzyme, ACE2, the effector peptide angiotensin-(1–7) (Ang-(1–7)) which mediates its effects via the putative receptor Mas (MasR), has also been implicated in the pathogenesis of liver fibrosis and portal hypertension. This system is activated in both preclinical animal models and human chronic liver disease and it is now well established that the alternate RAS counter-regulates many of the deleterious effects of the ACE-dependent classical RAS. Work from our laboratory has demonstrated that liver-specific ACE2 overexpression reduces hepatic fibrosis and liver perfusion pressure without producing off-target effects. In addition, recent studies suggest that the blockers of the receptors of alternate RAS, such as the MasR and Mas related G protein-coupled receptor type-D (MrgD), increase splanchnic vascular resistance in cirrhotic animals, and thus drugs targeting the alternate RAS may be useful in the treatment of portal hypertension. This review outlines the role of the RAS in liver fibrosis and portal hypertension with a special emphasis on the possible new therapeutic approaches targeting the ACE2-driven alternate RAS.

Nlrp3 Deficiency Alleviates Angiotensin II-Induced Cardiomyopathy by Inhibiting Mitochondrial Dysfunction

Inflammation has been considered a key component in the pathogenesis and progression of angiotensin II- (Ang II-) induced cardiac hypertrophy and related cardiomyopathy. As a vital mediator of inflammation, the role of the Nlrp3 inflammasome in Ang II-induced cardiomyopathy remains unclear. This study was aimed to determine whether Nlrp3 inflammasome activation and its downstream pathway were involved in Ang II-induced cardiomyopathy. We established an Ang II infusion model in both wild-type and Nlrp3-/- mice to determine the contribution of Nlrp3 to cardiac function. Cardiac fibrosis was determined by Masson's trichrome staining, real-time PCR, and TUNEL assay; cardiac function was assessed by echocardiography. Nlrp3 inflammasome activation and related downstream cytokines were measured by Western blotting and enzyme-linked immunosorbent assays; mitochondrial dysfunction was examined by transmission electron microscopy and real-time PCR. We found that Ang II-infused mice showed impaired cardiac function, as evidenced by increased cardiac fibrosis, apoptosis, inflammation, and left ventricular dysfunction. However, these alterations were significantly alleviated in the mice with Nlrp3 gene deletion. Moreover, Ang II-infused mice showed increased Nlrp3 inflammasome activity relative to that of the cytokines IL-1β and IL-18, increased reactive oxygen species, mitochondrial abnormalities, and decreased mtDNA copy number and ATP synthase activity. These molecular and pathological alterations were also attenuated in Nlrp3 deficient mice. In conclusion, Nlrp3 inflammasome-induced mitochondrial dysfunction is involved in Ang II-induced cardiomyopathy. Nlrp3 gene deletion attenuated mitochondrial abnormalities, cardiac inflammation, oxidative stress, and fibrosis and thus alleviated heart dysfunction and hypertrophy. Targeting the Nlrp3 inflammasome and/or mitochondria may be a therapeutic approach for Ang II-induced cardiac diseases.

Dual-ligand supramolecular nanofibers inspired by the renin-angiotensin system for the targeting and synergistic therapy of myocardial infarction

Rationale: The compensatory activation of the renin-angiotensin system (RAS) after myocardial infarction (MI) plays a crucial role in the pathogenesis of heart failure. Most existing studies on this subject focus on mono- or dual-therapy of blocking the RAS, which exhibit limited efficacy and often causes serious adverse reactions. Few studies have been conducted on targeted therapy based on the activated RAS post-MI. Thus, the development of multiple-functional nanomedicine with concurrent targeting ability and synergistic therapeutic effect against RAS may show great promise in improving cardiac function post-MI.

Methods: We utilized a cooperative self-assembly strategy constructing supramolecular nanofibers— telmisartan-doped co-assembly nanofibers (TDCNfs) to counter-regulate RAS through targeted delivery and combined therapy. TDCNfs were prepared through serial steps of solvent exchange, heating incubation, gelation, centrifugation, and lyophilization, in which the telmisartan was doped in the self-assembly process of Ang1-7 to obtain the co-assembly nanofibers wherein they act as both therapeutic agents and target-guide agents.

Results: TDCNfs exhibited the desired binding affinity to the two different receptors, AT1R and MasR. Through the dual ligand-receptor interactions to mediate the coincident downstream pathways, TDCNfs not only displayed favorably targeted properties to hypoxic cardiomyocytes, but also exerted synergistic therapeutic effects in apoptosis reduction, inflammatory response alleviation, and fibrosis inhibition in vitro and in vivo, significantly protecting cardiac function and mitigating post-MI adverse outcomes.

Conclusion: A dual-ligand nanoplatform was successfully developed to achieve targeted and synergistic therapy against cardiac deterioration post-MI. We envision that the integration of multiple therapeutic agents through supramolecular self-assembly would offer new insight for the systematic and targeted treatment of cardiovascular diseases.

ACE2: from protection of liver disease to propagation of COVID-19

Twenty years ago, the discovery of angiotensin-converting enzyme 2 (ACE2) was an important breakthrough dramatically enhancing our understanding of the renin-angiotensin system (RAS). The classical RAS is driven by its key enzyme ACE and is pivotal in the regulation of blood pressure and fluid homeostasis. More recently, it has been recognised that the protective RAS regulated by ACE2 counterbalances many of the deleterious effects of the classical RAS. Studies in murine models demonstrated that manipulating the protective RAS can dramatically alter many diseases including liver disease. Liver-specific overexpression of ACE2 in mice with liver fibrosis has proved to be highly effective in antagonising liver injury and fibrosis progression. Importantly, despite its highly protective role in disease pathogenesis, ACE2 is hijacked by SARS-CoV-2 as a cellular receptor to gain entry to alveolar epithelial cells, causing COVID-19, a severe respiratory disease in humans. COVID-19 is frequently life-threatening especially in elderly or people with other medical conditions. As an unprecedented number of COVID-19 patients have been affected globally, there is an urgent need to discover novel therapeutics targeting the interaction between the SARS-CoV-2 spike protein and ACE2. Understanding the role of ACE2 in physiology, pathobiology and as a cellular receptor for SARS-CoV-2 infection provides insight into potential new therapeutic strategies aiming to prevent SARS-CoV-2 infection related tissue injury. This review outlines the role of the RAS with a strong focus on ACE2-driven protective RAS in liver disease and provides therapeutic approaches to develop strategies to prevent SARS-CoV-2 infection in humans.

Stable Plasma Sample Storage in Acetonitrile for Angiotensin and Aldosterone Analysis

BACKGROUND

Angiotensin I, II (AI, AII) and aldosterone are unstable in plasma specimens at room temperature, making it difficult for collect samples for remote regions in centralized and collaborative studies. Here we introduce a stable storage method which do not require cold conditions..

METHODS

Acetonitrile was added to the plasma to 60%, and then the supernatants were kept at 4°C and room temperature for 0, 1, 2, 3, 10 and 30 days. AI, AII and aldosterone were extracted and analyzed by chemiluminescence immunoassays.

RESULTS

AI, AII and aldosterone were well retained in the supernatant under this method. The intra- and inter-day CVs of this method were all below 10%. The levels of AI, AII and aldosterone by this method remained stable for 30 days at room temperature.

CONCLUSION

Addition of 60% acetonitrile in the plasma provides a stable storage method for clinical AI, AII and aldosterone.

Dapagliflozin for Heart Failure with Preserved Ejection Fraction: Will the DELIVER Study Deliver?

Drug therapies for people with heart failure and preserved ejection fraction (HFpEF) are often limited to diuretics to improve symptoms as no therapies demonstrate a mortality benefit in this cohort. People with diabetes have a high risk of developing HFpEF and vice versa, suggesting shared pathophysiological mechanisms exist, which in turn engenders the potential for shared treatments. Dapagliflozin is a sodium-glucose co-transporter 2 (SGLT2) inhibitor which has demonstrated significantly improved cardiovascular and hospitalisation for heart failure (HHF) outcomes in previous cardiovascular outcome trials (CVOTs). These CVOTs include the DECLARE-TIMI and DAPA-HF studies which observed significant benefits for people with heart failure and specifically those with heart failure and reduced ejection fraction (HFrEF), respectively. The ongoing DELIVER study is evaluating the use of dapagliflozin specifically in people with HFpEF, which may have enormous implications for treatment and considerable economic consequences. This will complement previous and other ongoing CVOTs evaluating dapagliflozin use. In this review we discuss the use of SGLT2 inhibitors in HFrEF and HFpEF with a focus on the DELIVER study and its potential health and economic implications.

Are SGLT-2 Inhibitors the Future of Heart Failure Treatment? The EMPEROR-Preserved and EMPEROR-Reduced Trials

Heart failure is frequently associated with diabetes, and therapies which reduce mortality in people with heart failure and reduced ejection fraction (HFrEF) are often limited to drugs which modulate the renin-angiotensin-aldosterone system or heart rate control and occasionally to device therapy. Treatment is even more challenging in people with heart failure and preserved ejection fraction (HFpEF), with currently no approved therapy demonstrating a mortality-improving effect, limiting treatment to diuretics for the alleviation of the symptoms of fluid overload and risk factor management. Previous cardiovascular outcome trials for sodium-glucose co-transporter-2 (SGLT-2) inhibitors have demonstrated significant favourable outcomes for cardiovascular disease, heart failure hospitalisation and all-cause mortality. The aim of the nearly completed EMPEROR-preserved and EMPEROR-reduced trials is to determine the impact of empagliflozin on cardiovascular and heart failure outcomes in people with HFpEF or HFrEF with or without diabetes. The trials will add substantially to our understanding of SGLT-2 inhibitors in the treatment of HFrEF and may have major implications for the treatment of people with HFpEF. The study will also be powered to address the impact of empagliflozin on changes in renal function in people with and without diabetes and incident diabetes in the participants without diabetes at baseline. In this article we discuss the rationale for using SGLT-2 inhibitors in people with heart failure and explore the potential findings and importance of the ongoing EMPEROR-preserved and EMPEROR-reduced trials.

Impact of Angiotensin II Receptor Blockers on Clinical Outcomes after Percutaneous Coronary Intervention in Patients with Acute Myocardial Infarction Based on Data from the Korean National Health Insurance Database (2005-2014)

Background and Objectives

The effectiveness of angiotensin II receptor blockers (ARBs) compared with angiotensin converting enzyme inhibitors (ACEIs) in patients with acute myocardial infarction (AMI) has not been established. We investigated the effects of ARBs on clinical outcomes after percutaneous coronary intervention (PCI) in AMI patients.

Methods

Patients receiving ACEIs or ARBs after AMI treated with PCI between January 2005 and December 2014 were selected from the Korean National Health Insurance Service database. The primary endpoint was major cardiovascular adverse event (MACE; all-cause death, myocardial infarct [MI], or stroke).

Results

We included patients regularly taking ACEIs (n=22,331) or ARBs (n=28,533) (medication possession ratio ≥80%). Compared with the ACEI group, the ARB group contained more females (31% vs. 18%), were older (mean, 63 vs. 60 years), and had more comorbidities, including hypertension (62.8% vs. 44.8%), diabetes (33.9% vs. 26.4%), congestive heart failure (7.9% vs. 4.3%), chronic obstructive pulmonary disease (25.5% vs. 18.9%), and end-stage renal disease (1.3% vs. 0.4%) (p<0.001 for all). After propensity score–matching, ARBs were associated with a 23% lower risk of MACE (hazard ratio [HR], 0.774; 95% confidence interval [CI], 0.715–0.838; p<0.001) than ACEIs. ARB use was also associated with a significantly reduced risk of death (HR, 0.741; 95% CI, 0.659–0.834; p<0.001), MI (HR, 0.731; 95% CI, 0.638–0.837; p<0.001), and revascularization (HR, 0.816; 95% CI, 0.773–0.861; p<0.001).

Conclusions

ARB use was associated with a lower risk of MACE, MI, and revascularization than ACEIs in our retrospective analysis of AMI patients who underwent PCI.

Use of sacubitril/valsartan as 'bridge to transplant' in patients with end-stage hypertrophic cardiomyopathy

The end stage or burned-out phase is an uncommon but challenging clinical evolution of hypertrophic cardiomyopathy (HCM). The management of end-stage HCM is empirically based on the use of drugs approved for heart failure with reduced ejection fraction; however, cardiac transplantation often represents the best option to improve survival. In our case, we describe the use of sacubitril/valsartan as a 'bridge to transplant' in a patient with end-stage HCM. After introducing the drug, enhancements in functional capacity, a reduction in natriuretic peptides and an increase in left ventricular ejection fraction occurred. Given their improved volume of oxygen consumption (VO₂) peak and hemodynamic parameters, our patient was left off the waiting list for cardiac transplant and continues to be regularly followed-up with every 3 months.

Prevention and treatment of radiotherapy-induced side effects

Radiotherapy remains a mainstay of cancer treatment, being used in roughly 50% of patients. The precision with which the radiation dose can be delivered is rapidly improving. This precision allows the more accurate targeting of radiation dose to the tumor and reduces the amount of surrounding normal tissue exposed. Although this often reduces the unwanted side effects of radiotherapy, we still need to further improve patients' quality of life and to escalate radiation doses to tumors when necessary. High-precision radiotherapy forces one to choose which organ or functional organ substructures should be spared. To be able to make such choices, we urgently need to better understand the molecular and physiological mechanisms of normal tissue responses to radiotherapy. Currently, oversimplified approaches using constraints on mean doses, and irradiated volumes of normal tissues are used to plan treatments with minimized risk of radiation side effects. In this review, we discuss the responses of three different normal tissues to radiotherapy: the salivary glands, cardiopulmonary system, and brain. We show that although they may share very similar local cellular processes, they respond very differently through organ-specific, nonlocal mechanisms. We also discuss how a better knowledge of these mechanisms can be used to treat or to prevent the effects of radiotherapy on normal tissue and to optimize radiotherapy delivery.

The historical evolution of knowledge of the involvement of neurohormonal systems in the pathophysiology and treatment of heart failure

Our knowledge of the pathophysiology of heart failure (HF) underwent profound changes during the 1980s. Once thought to be of exclusively structural origin, HF began to be seen as the consequence of hormonal imbalance. A number of seminal studies were published in that decade focusing on the impact of neurohormonal activation in HF. Presently, eight neurohormonal systems are known to have a key role in HF development: four stimulate vasoconstriction and sodium/water retention (the sympathetic nervous system, the renin-angiotensin-aldosterone system [RAAS], endothelin, and the vasopressin-arginine system), while the other four stimulate vasodilation and natriuresis (the prostaglandin system, nitric oxide, the dopaminergic system, and the natriuretic peptide system [NPS]). These systems are strongly interconnected and are subject to intricate regulation, functioning together in a delicate homeostasis. Disruption of this homeostasis is characteristic of HF. This review explores the historical development of knowledge on the impact of the neurohormonal systems on HF pathophysiology, from the first studies to current understanding. In addition, the therapeutic potential of each of these systems is discussed, and currently used neurohormonal antagonists are characterized. Special emphasis is given to the latest drug approved for use in HF with reduced ejection fraction, sacubitril/valsartan. This drug combines two different molecules, acting on two different systems (RAAS and NPS) simultaneously.

Alamandine enhances cardiomyocyte contractility in hypertensive rats through a nitric oxide-dependent activation of CaMKII

Overstimulation of the renin-angiotensin system (RAS) has been implicated in the pathogenesis of various cardiovascular diseases. Alamandine is a peptide newly identified as a protective component of the RAS; however, the mechanisms involved in its beneficial effects remain elusive. By using a well-characterized rat model of hypertension, the TGR (mREN2)27, we show that mREN ventricular myocytes are prone to contractile enhancement mediated by short-term alamandine (100 nmol/L) stimulation of Mas-related G protein-coupled receptor member D (MrgD) receptors, while Sprague-Dawley control cells showed no effect. Additionally, alamandine prevents the Ca²⁺ dysregulation classically exhibited by freshly isolated mREN myocytes. Accordingly, alamandine treatment of mREN myocytes attenuated Ca²⁺ spark rate and enhanced Ca²⁺ reuptake to the sarcoplasmic reticulum. Along with these findings, KN-93 fully inhibited the alamandine-induced increase in Ca²⁺ transient magnitude and phospholamban (PLN) phosphorylation at Thr17, indicating CaMKII as a downstream effector of the MrgD signaling pathway. In mREN ventricular myocytes, alamandine treatment induced significant nitric oxide (NO) production. Importantly, NO synthase inhibition prevented the contractile actions of alamandine, including PLN-Thr17 phosphorylation at the CaMKII site, thereby indicating that NO acts upstream of CaMKII in the alamandine downstream signaling. Altogether, our results show that enhanced contractile responses mediated by alamandine in cardiomyocytes from hypertensive rats occur through a NO-dependent activation of CaMKII.

Angiotensin Receptor Blockers as an Alternative to Angiotensin-Converting Enzyme Inhibitors in Patients with Acute Myocardial Infarction Undergoing Percutaneous Coronary Intervention

BACKGROUND

Angiotensin-converting enzyme inhibitors (ACEIs) are the first choice for the treatment of acute myocardial infarction (AMI), and angiotensin receptor blockers (ARBs) should be considered in patients intolerant to ACEIs. Although previous studies support the use of ARBs as an alternative to ACEIs, these studies showed inconsistent results. The objective of this study was to demonstrate the clinical impact of ARBs as an alternative to ACEIs in patients with AMI undergoing percutaneous coronary intervention (PCI).

METHODS

The CardiOvascular Risk and idEntificAtion of potential high-risk population in AMI (COREA-AMI) registry enrolled all consecutive patients with AMI undergoing PCI. The primary endpoint was the composite of cardiovascular death, myocardial infarction, stroke, or hospitalization due to heart failure.

RESULTS

Of the 3,328 eligible patients, ARBs replaced ACEIs in 816 patients, while 824 patients continued to use ACEIs and 826 patients continued to use ARBs. The remaining 862 patients did not receive ACEIs/ARBs. After the adjustment with inverse probability weighting, the primary endpoints in the first groups were similar (7.5% vs. 8.0%, hazard ratio [HR], 0.89; 95% confidence interval [CI], 0.75-1.05; P = 0.164). Composite events were less frequent in the ACEI to ARB group than no ACEI/ARB group (7.5% vs. 11.8%, HR, 0.76; 95% CI, 0.64-0.90; P = 0.002).

CONCLUSION

The alternative use of ARBs following initial treatment with ACEIs demonstrates comparable clinical outcomes to those with continued use of ACEIs and is associated with an improved rate of composite events compared to no ACEI/ARB use in patients with AMI undergoing PCI.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02385682.

Reversal of heart failure in a chemogenetic model of persistent cardiac redox stress

We previously described a novel "chemogenetic" animal model of heart failure that recapitulates a characteristic feature commonly found in human heart failure: chronic oxidative stress. This heart failure model uses a chemogenetic approach to activate a recombinant yeast d-amino acid oxidase in rat hearts in vivo to generate oxidative stress, which then rapidly leads to the development of a dilated cardiomyopathy. Here we apply this new model to drug testing by studying its response to treatment with the angiotensin II (ANG II) receptor blocker valsartan, administered either alone or with the neprilysin inhibitor sacubitril. Echocardiographic and [¹⁸F]fluorodeoxyglucose positron emission tomographic imaging revealed that valsartan in the presence or absence of sacubitril reverses the anatomical and metabolic remodeling induced by chronic oxidative stress. Markers of oxidative stress, mitochondrial function, and apoptosis, as well as classical heart failure biomarkers, also normalized following drug treatments despite the persistence of cardiac fibrosis. These findings provide evidence that chemogenetic heart failure is rapidly reversible by drug treatment, setting the stage for the study of novel heart failure therapeutics in this model. The ability of ANG II blockade and neprilysin inhibition to reverse heart failure induced by chronic oxidative stress identifies a central role for cardiac myocyte angiotensin receptors in the pathobiology of cardiac dysfunction caused by oxidative stress.NEW & NOTEWORTHY The chemogenetic approach allows us to distinguish cardiac myocyte-specific pathology from the pleiotropic changes that are characteristic of other "interventional" animal models of heart failure. These features of the chemogenetic heart failure model facilitate the analysis of drug effects on the progression and regression of ventricular remodeling, fibrosis, and dysfunctional signal transduction. Chemogenetic approaches will be highly informative in the study of the roles of redox stress in heart failure providing an opportunity for the identification of novel therapeutic targets.

The Role of Angiotensin-(1-7)/Mas Axis and Angiotensin Type 2 Receptors in the Central Nervous System in Cardiovascular Disease and Therapeutics: A Riddle to be Solved

In recent years, the Angiotensin-(1-7)/Mas receptor [Ang-(1-7)/Mas] sub-branch of the Renin-Angiotensin System (RAS) in the brain, and Angiotensin Type 2 Receptors (AT2R), have attracted scientific interest, as there is evidence that they constitute an essential pathway in cardiovascular regulation, in health and in disease. By acting centrally, the Ang-(1-7)/Mas axis - that has been termed 'the axis of good'- can exert blood pressure-lowering effects, while also favourably altering baroreflex sensitivity and noradrenergic neurotransmission. Thus, research has focused on the possible neuro- and cardioprotective effects of this pathway in the setting of cardiovascular disease, ultimately aiming to evaluate the potential for development of novel therapeutic strategies based on its modulation. We summarize the available evidence from experimental studies in this context, aiming to assess current limits of scientific knowledge relevant to this newly-described 'player' in haemodynamic regulation, that may become a potential therapeutic target.

NR4A nuclear receptors in cardiac remodeling and neurohormonal regulation

Heart failure is characterized by the constant interplay between the underlying cardiac insult, degree of myocardial dysfunction and the activity of compensatory neurohormonal mechanisms. The sympathetic nervous system (SNS) and renin-angiotensin-aldosterone system (RAAS) become activated to maintain cardiac output; however, their chronic hyperactivity will eventually become deleterious. Several nuclear hormone receptors, including the mineralocorticoid receptor and estrogen receptor, are well-known to modulate cardiac disease. Recently, the subfamily of NR4A nuclear receptors i.e. Nur77, Nurr1 and NOR-1, are emerging as key players in cardiac stress responses, as well as pivotal regulators of neurohormonal mechanisms. In this review, we summarize current literature on NR4A nuclear receptors in the heart and in various components of the SNS, RAAS and immune system and discuss the functional implications for NR4As in cardiac function and disease.

Cellular mechanisms of metabolic syndrome-related atrial decompensation in a rat model of HFpEF

Heart failure (HF) with preserved ejection fraction (HFpEF) is present in about 50% of HF patients. Atrial remodeling is common in HFpEF and associated with increased mortality. We postulate that atrial remodeling is associated with atrial dysfunction in vivo related to alterations in cardiomyocyte Calcium (Ca) signaling and remodeling. We examined atrial function in vivo and Ca transients (CaT) (Fluo4-AM, field stim) in atrial cardiomyocytes of ZSF-1 rats without (Ln; lean hypertensive) and with metabolic syndrome (Ob; obese, hypertensive, diabetic) and HFpEF.

RESULTS

At 21weeks Ln showed an increased left ventricular (LV) mass and left ventricular end-diastolic pressure (LVEDP), but unchanged left atrial (LA) size and preserved atrial ejection fraction vs. wild-type (WT). CaT amplitude in atrial cardiomyocytes was increased in Ln (2.9±0.2 vs. 2.3±0.2F/F₀ in WT; n=22 cells/group; p<0.05). Studying subcellular Ca release in more detail, we found that local central cytosolic CaT amplitude was increased, while subsarcolemmal CaT amplitudes remained unchanged. Moreover, Sarcoplasmic reticulum (SR) Ca content (caffeine) was preserved while Ca spark frequency and tetracaine-dependent SR Ca leak were significantly increased in Ln. Ob mice developed a HFpEF phenotype in vivo, LA area was significantly increased and atrial in vivo function was impaired, despite increased atrial CaT amplitudes in vitro (2.8±0.2; p<0.05 vs. WT). Ob cells showed alterations of the tubular network possibly contributing to the observed phenotype. CaT kinetics as well as SR Ca in Ob were not significantly different from WT, but SR Ca leak remained increased. Angiotensin II (Ang II) reduced in vitro cytosolic CaT amplitudes and let to active nuclear Ca release in Ob but not in Ln or WT.

SUMMARY

In hypertensive ZSF-1 rats, a possibly compensatory increase of cytosolic CaT amplitude and increased SR Ca leak precede atrial remodeling and HFpEF. Atrial remodeling in ZSF-1 HFpEF is associated with an altered tubular network in-vitro and atrial contractile dysfunction in vivo, indicating insufficient compensation. Atrial cardiomyocyte dysfunction in vitro is induced by the addition of angiotensin II.

The CARMA3-Bcl10-MALT1 Signalosome Drives NFκB Activation and Promotes Aggressiveness in Angiotensin II Receptor-Positive Breast Cancer

The angiotensin II receptor AGTR1, which mediates vasoconstrictive and inflammatory signaling in vascular disease, is overexpressed aberrantly in some breast cancers. In this study, we established the significance of an AGTR1-responsive NFκB signaling pathway in this breast cancer subset. We documented that AGTR1 overexpression occurred in the luminal A and B subtypes of breast cancer, was mutually exclusive of HER2 expression, and correlated with aggressive features that include increased lymph node metastasis, reduced responsiveness to neoadjuvant therapy, and reduced overall survival. Mechanistically, AGTR1 overexpression directed both ligand-independent and ligand-dependent activation of NFκB, mediated by a signaling pathway that requires the triad of CARMA3, Bcl10, and MALT1 (CBM signalosome). Activation of this pathway drove cancer cell-intrinsic responses that include proliferation, migration, and invasion. In addition, CBM-dependent activation of NFκB elicited cancer cell-extrinsic effects, impacting endothelial cells of the tumor microenvironment to promote tumor angiogenesis. CBM/NFκB signaling in AGTR1⁺ breast cancer therefore conspires to promote aggressive behavior through pleiotropic effects. Overall, our results point to the prognostic and therapeutic value of identifying AGTR1 overexpression in a subset of HER2-negative breast cancers, and they provide a mechanistic rationale to explore the repurposing of drugs that target angiotensin II-dependent NFκB signaling pathways to improve the treatment of this breast cancer subset.Significance: These findings offer a mechanistic rationale to explore the repurposing of drugs that target angiotensin action to improve the treatment of AGTR1-expressing breast cancers. Cancer Res; 78(5); 1225-40. ©2017 AACR.

Heart Failure With Preserved, Borderline, and Reduced Ejection Fraction: 5-Year Outcomes

BACKGROUND

Patients with heart failure (HF) have a poor prognosis and are categorized by ejection fraction (EF).

OBJECTIVES

This study sought to characterize differences in outcomes in patients hospitalized with heart failure with preserved ejection fraction (HFpEF) (EF ≥50%), heart failure with borderline ejection fraction (HFbEF) (EF 41% to 49%), and heart failure with reduced ejection fraction (HFrEF) (EF ≤40%).

METHODS

Data from GWTG-HF (Get With The Guidelines-Heart Failure) were linked to Medicare data for longitudinal follow-up. Multivariable models were constructed to examine 5-year outcomes and to compare survival to median survival of the U.S.

POPULATION

RESULTS

A total of 39,982 patients from 254 hospitals who were admitted for HF between 2005 and 2009 were included: 18,299 (46%) had HFpEF, 3,285 (8.2%) had HFbEF, and 18,398 (46%) had HFrEF. Overall, median survival was 2.1 years. In risk-adjusted survival analysis, all 3 groups had similar 5-year mortality (HFrEF 75.3% vs. HFpEF 75.7%; hazard ratio: 0.99 [95% confidence interval: 0.958 to 1.022]; HFbEF 75.7% vs. HFpEF 75.7%; hazard ratio: 0.99 [95% confidence interval: 0.947 to 1.046]). In risk-adjusted analyses, the composite of mortality and rehospitalization was similar for all subgroups. Cardiovascular and HF readmission rates were higher in those with HFrEF and HFbEF compared with those with HFpEF. When compared with the U.S. population, HF patients across all age and EF groups had markedly lower median survival.

CONCLUSIONS

Among patients hospitalized with HF, patients across the EF spectrum have a similarly poor 5-year survival with an elevated risk for cardiovascular and HF admission. These findings underscore the need to improve treatment of patients with HF.

Clinical and Hemodynamic Effects of Endothelin Receptor Antagonists in Patients With Heart Failure

The clinical benefit of endothelin receptor antagonists (ERA) for the management of heart failure (HF) remains controversial. To examine this question, we performed a meta-analysis of randomized controlled trials (RCTs) to investigate the clinical and hemodynamic effects of ERA in HF patients.We searched the PubMed, Medline, Embase, and Cochrane Library from inception to March 20, 2016 to identify the pertinent studies. Risk ratio (RR) and weighted mean difference (WMD) were calculated using a fixed or random effect model.A total of 15 RCTs with 3,624 HF patients were included. Compared with control groups, ERA might not improve the mortality (RR 1.12, 95%CI 0.81 to 1.54, P = 0.51) or incidence of worsening HF or cardiovascular events (WHF/ CVE) (RR 1.06, 95%CI 0.94 to 1.19, P = 0.35) in HF patients. Subgroup analysis also suggested that neither nonselective nor selective ERAs had an impact on mortality and WHF/CVE. However, the hemodynamic variables of HF patients, including cardiac index (WMD 0.32, 95%CI 0.22 to 0.43, P < 0.01), pulmonary capillary wedge pressure (WMD -3.10, 95%CI -3.99 to -2.20, P < 0.01), mean pulmonary arterial pressure (WMD -4.42, 95%CI -5.50 to -3.33, P < 0.01), systemic vascular resistance (WMD -276.35, 95%CI -399.62 to -153.09, P < 0.01), and pulmonary vascular resistance (WMD -69.42, 95%CI -105.33 to -33.52, P < 0.01) were significantly improved by ERA.In conclusion, this meta-analysis suggests that ERA therapy could effectively improve cardiac output and pulmonary and systemic hemodynamics, but with less benefit to the clinical outcomes of HF patients.

Targeting Metabolic Modulation and Mitochondrial Dysfunction in the Treatment of Heart Failure

Despite significant improvements in morbidity and mortality with current evidence-based pharmaceutical-based treatment of heart failure (HF) over the previous decades, the burden of HF remains high. An alternative approach is currently being developed, which targets myocardial energy efficiency and the dysfunction of the cardiac mitochondria. Emerging evidence suggests that the insufficient availability of ATP to the failing myocardium can be attributed to abnormalities in the myocardial utilisation of its substrates rather than an overall lack of substrate availability. Therefore, the development of potential metabolic therapeutics has commenced including trimetazidine, ranolazine and perhexiline, as well as specific mitochondrial-targeting pharmaceuticals, such as elamipretide. Large randomised controlled trials are required to confirm the role of metabolic-modulating drugs in the treatment of heart failure, but early studies have been promising in their possible efficacy for the management of heart failure in the future.

Cardioprotective role of zofenopril in hypertensive patients with acute myocardial infarction: a pooled individual data analysis of the SMILE studies

PURPOSE

The four SMILE studies demonstrated that early administration of zofenopril following acute myocardial infarction is prognostically beneficial compared to placebo or other angiotensin-converting enzyme (ACE) inhibitors. In the present retrospective pooled analysis of individual SMILE studies, we evaluated the efficacy of zofenopril on cardiovascular (CV) outcomes in 1880 hypertensive and 1662 normotensive patients.

MATERIALS AND METHODS

Four hundred and forty-nine hypertensives and 486 normotensives were treated with placebo, 980 and 786 with zofenopril 30-60 mg daily, 252 and 259 with lisinopril 5-10 mg daily, 199 and 131 with ramipril 10 mg daily, for 6 to 48 weeks.

RESULTS

The 1-year risk of death or hospitalization for CV causes was significantly reduced with zofenopril and lisinopril vs. placebo in both hypertensive (HR: 0.65; 95%CI: 0.48-0.86; p = .003 and .60, .36-.99; p = .049, respectively) and normotensive patients (0.56, 0.42-0.75; p = .0001 and .51, .28-.90; p = .020), whereas this was not the case for ramipril (hypertensives: 1.02, 0.69-1.52; p = .918; normotensives: 0.91, 0.59-1.41; p = .670). Zofenopril significantly reduced the risk of CV outcomes vs. the other two ACE-inhibitors pooled together in hypertensive (0.76; 0.58-0.99; p = .045), but not in normotensive patients (0.77; 0.55-1.10; p = .150).

CONCLUSIONS

In cardiac patients of the SMILE studies with arterial hypertension treatment with the ACE-inhibitor zofenopril was beneficial in reducing the 1-year risk of CV events as compared to placebo and ramipril. An efficacy similar to that of zofenopril was observed with lisinopril.

Experimental Evidences Supporting the Benefits of Exercise Training in Heart Failure

Heart Failure (HF), a common end point for many cardiovascular diseases, is a syndrome with a very poor prognosis. Although clinical trials in HF have achieved important outcomes in reducing mortality, little is known about functional mechanisms conditioning health improvement in HF patients. In parallel with clinical studies, basic science has been providing important discoveries to understand the mechanisms underlying the pathophysiology of HF, as well as to identify potential targets for the treatment of this syndrome. In spite of being the end-point of cardiovascular derangements caused by different etiologies, autonomic dysfunction, sympathetic hyperactivity, oxidative stress, inflammation and hormonal activation are common factors involved in the progression of this syndrome. Together these causal factors create a closed link between three important organs: brain, heart and the skeletal muscle. In the past few years, we and other groups have studied the beneficial effects of aerobic exercise training as a safe therapy to avoid the progression of HF. As summarized in this chapter, exercise training, a non-pharmacological tool without side effects, corrects most of the HF-induced neurohormonal and local dysfunctions within the brain, heart and skeletal muscles. These adaptive responses reverse oxidative stress, reduce inflammation, ameliorate neurohormonal control and improve both cardiovascular and skeletal muscle function, thus increasing the quality of life and reducing patients' morbimortality.

Effects of angiotensin-converting-enzyme inhibitor therapy on the regulation of the plasma and cardiac tissue renin-angiotensin system in heart transplant patients

BACKGROUND

Angiotensin-converting enzyme (ACE) inhibitors (ACEis) are beneficial in patients with heart failure, yet their role after heart transplantation (HTx) remains ambiguous. Particularly, the effects of ACEis on plasma and cardiac metabolites of the "classical" and "alternative" renin-angiotensin system (RAS) in HTx patients are unknown.

METHODS

This cross-sectional study used a novel mass spectrometry-based approach to analyze plasma and tissue RAS regulation in homogenates of heart biopsy specimens from 10 stable HTx patients without RAS blockade and in 15 patients with ACEi therapy. Angiotensin (Ang) levels in plasma and Ang formation rates in biopsy tissue homogenates were measured.

RESULTS

Plasma Ang II formation is exclusively ACE dependent, whereas cardiac Ang II formation is primarily chymase dependent in HTx patients. ACEi therapy substantially increased plasma Ang-(1-7), the key effector of the alternative RAS, leaving plasma Ang II largely intact. Importantly, neprilysin and prolyl-carboxypeptidase but not angiotensin converting enzyme 2 are essential for cardiac tissue Ang-(1-7) formation.

CONCLUSION

ACE is the key enzyme for the generation of plasma Ang II, whereas chymase is responsible for cardiac tissue production of Ang II. Furthermore, our findings reveal that neprilysin and prolyl-carboxypeptidase are the essential cardiac enzymes for the alternative RAS after HTx. These novel insights into the versatile regulation of the RAS in HTx patients might affect future therapeutic avenues, such as chymase and neprilysin inhibition, beyond classical Ang II blockade.

A sustained-release drug-delivery system of synthetic prostacyclin agonist, ONO-1301SR: a new reagent to enhance cardiac tissue salvage and/or regeneration in the damaged heart

Cardiac failure is a major cause of mortality and morbidity worldwide, since the standard treatment for cardiac failure in the clinical practice is chiefly to focus on removal of insults against the heart or minimisation of additional factors to exacerbate cardiac failure, but not on regeneration of the damaged cardiac tissue. A synthetic prostacyclin agonist, ONO-1301, has been developed as a long-acting drug for acute and chronic pathologies related to regional ischaemia, inflammation and/or interstitial fibrosis by pre-clinical studies. In addition, poly-lactic co-glycolic acid-polymerised form of ONO-1301, ONO-1301SR, was generated to achieve a further sustained release of this drug into the targeted region. This unique reagent has been shown to act on fibroblasts, vascular smooth muscle cells and endothelial cells in the tissue via the prostaglandin IP receptor to exert paracrinal release of multiple protective factors, such as hepatocyte growth factor, vascular endothelial growth factor or stromal cell-derived factor-1, into the adjacent damaged tissue, which is salvaged and/or regenerated as a result. Our laboratory developed a new surgical approach to treat acute and chronic cardiac failure using a variety of animal models, in which ONO-1301SR is directly placed over the cardiac surface to maximise the therapeutic effects and minimise the systemic complications. This review summarises basic and pre-clinical information of ONO-1301 and ONO-1301SR as a new reagent to enhance tissue salvage and/or regeneration, with a particular focus on the therapeutic effects on acute and chronic cardiac failure and underlying mechanisms, to explore a potential in launching the clinical study.

Aging and the cardiac collagen matrix: Novel mediators of fibrotic remodelling

Cardiovascular disease is a leading cause of death worldwide and there is a pressing need for new therapeutic strategies to treat such conditions. The risk of developing cardiovascular disease increases dramatically with age, yet the majority of experimental research is executed using young animals. The cardiac extracellular matrix (ECM), consisting predominantly of fibrillar collagen, preserves myocardial integrity, provides a means of force transmission and supports myocyte geometry. Disruptions to the finely balanced control of collagen synthesis, post-synthetic deposition, post-translational modification and degradation may have detrimental effects on myocardial functionality. It is now well established that the aged heart is characterized by fibrotic remodelling, but the mechanisms responsible for this are incompletely understood. Furthermore, studies using aged animal models suggest that interstitial remodelling with disease may be age-dependent. Thus with the identification of new therapeutic strategies targeting fibrotic remodelling, it may be necessary to consider age-dependent mechanisms. In this review, we discuss remodelling of the cardiac collagen matrix as a function of age, whilst highlighting potential novel mediators of age-dependent fibrotic pathways.

From Bench to Bedside: New Approaches to Therapeutic Discovery for Heart Failure

Heart failure is a significant global health problem, which is becoming worse as the population ages, and remains one of the biggest burdens on our economy. Despite significant advances in cardiovascular medicine, management and surgery, mortality rates remain high, with almost half of patients with heart failure dying within five years of diagnosis. As a multifactorial clinical syndrome, heart failure still represents an epidemic threat, highlighting the need for deeper insights into disease mechanisms and the development of innovative therapeutic strategies for both treatment and prevention. In this review, we discuss conventional heart failure therapies and highlight new pharmacological agents targeting pathophysiological features of the failing heart, for example, non-coding RNAs, angiotensin receptor-neprilysin inhibitors, cardiac myosin activators, BGP-15 and molecules targeting GRK2 including M119, gallein and paroxetine. Finally, we address the disparity between phase II and phase III clinical trials that prevent the translation of emerging HF therapies into new and approved therapies.

Cardiac stem cells transplantation enhances the expression of connexin 43 via the ANG II/AT1R/TGF-beta1 signaling pathway in a rat model of myocardial infarction

BACKGROUND

In this study, we hypothesized that CSCs mediated the expression of Cx43 after transplantation post MI via the ANG II/AT1R/TGF-beta1 signaling pathway.

METHODS

Myocardial infarction (MI) was induced in twenty male Sprague-Dawley rats. The rats were randomized into two groups and were then received the injection of 5 × 10(6) CSCs labeled with PKH26 in phosphate buffer solution (PBS) or equal PBS alone into the infarct anterior ventricular free wall two weeks after MI. Six weeks later, relevant signaling molecules involved were all examined.

RESULTS

In the CSCs group, an increased expression of Cx43 could be observed in different zones of the left ventricle (P<0.01). There was a significant reduction of the angiotensin II (ANG II) level in plasma and different regions of the left ventricular cardiac tissues (P<0.05; P<0.01). The angiotensin II type I receptor (AT1R) was decreased accompanied with an enhanced expression of angiotensin II type II receptor (AT2R) (P<0.01). Transforming growth factor beta-1(TGF-beta1) was downregulated (P<0.01). The expression of mothers against decapentaplegic homolog (SMAD) proteins including SMAD2 and SMAD3 was attenuated whereas SMAD7 was elevated (P<0.01, P<0.01, P<0.05). In addition, the expression of mitogen-activated protein kinases (MAPKs) including extracellular kinases 1/2 (ERK1/2) and p38 was also found to be reduced (P<0.01).

CONCLUSION

CSCs transplantation could enhance the level of Cx43 after MI. They might function through intervening the ANGII/AT1R/TGF-beta1 signaling pathway to regulate the expression of Cx43.

Mas receptor mediates cardioprotection of angiotensin-(1-7) against Angiotensin II-induced cardiomyocyte autophagy and cardiac remodelling through inhibition of oxidative stress

Angiotensin II (Ang II) plays an important role in the onset and development of cardiac remodelling associated with changes of autophagy. Angiotensin1-7 [Ang-(1-7)] is a newly established bioactive peptide of renin-angiotensin system, which has been shown to counteract the deleterious effects of Ang II. However, the precise impact of Ang-(1-7) on Ang II-induced cardiomyocyte autophagy remained essentially elusive. The aim of the present study was to examine if Ang-(1-7) inhibits Ang II-induced autophagy and the underlying mechanism involved. Cultured neonatal rat cardiomyocytes were exposed to Ang II for 48 hrs while mice were infused with Ang II for 4 weeks to induce models of cardiac hypertrophy in vitro and in vivo. LC3b-II and p62, markers of autophagy, expression were significantly elevated in cardiomyocytes, suggesting the presence of autophagy accompanying cardiac hypertrophy in response to Ang II treatment. Besides, Ang II induced oxidative stress, manifesting as an increase in malondialdehyde production and a decrease in superoxide dismutase activity. Ang-(1-7) significantly retarded hypertrophy, autophagy and oxidative stress in the heart. Furthermore, a role of Mas receptor in Ang-(1-7)-mediated action was assessed using A779 peptide, a selective Mas receptor antagonist. The beneficial responses of Ang-(1-7) on cardiac remodelling, autophagy and oxidative stress were mitigated by A779. Taken together, these result indicated that Mas receptor mediates cardioprotection of angiotensin-(1-7) against Ang II-induced cardiomyocyte autophagy and cardiac remodelling through inhibition of oxidative stress.

Transforming growth factor beta1 and aldosterone

PURPOSE OF REVIEW

It is well established that blocking the renin-angiotensin-aldosterone system (RAAS) is effective for the treatment of cardiovascular and renal complications in hypertension and diabetes mellitus. Although the induction of transforming growth factor beta1 (TGFbeta1) by components of the RAAS mediates the hypertrophic and fibrogenic changes in cardiovascular-renal complications, it is still controversial as to whether TGFbeta1 can be a target to prevent such complications. Here, we review recent findings on the role of TGFbeta1 in fluid homeostasis, focusing on the relationship with aldosterone.

RECENT FINDINGS

TGFbeta1 suppresses the adrenal production of aldosterone and renal tubular sodium reabsorption. We have generated mice with TGFbeta1 mRNA expression graded in five steps, from 10 to 300% of normal, and found that blood pressure and plasma volume are negatively regulated by TGFbeta1. Notably, the 10% hypomorph exhibits primary aldosteronism and sodium and water retention due to markedly impaired urinary excretion of water and electrolytes.

SUMMARY

These results identify TGFbeta signalling as an important counterregulatory system against aldosterone. Understanding the molecular mechanisms for the suppressive effects of TGFbeta1 on adrenocortical and renal function may further our understanding of primary aldosteronism, as well as assist in the development of novel therapeutic strategies for hypertension.

New medical therapies for heart failure

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

Challenging aspects of treatment strategies in heart failure with preserved ejection fraction: "Why did recent clinical trials fail?"

Heart failure (HF) is the leading cause of hospitalization among older adults and the prevalence is growing with the aging populations in the Western countries. Epidemiologic reports suggest that approximately 50% of patients who have signs or symptoms of HF have preserved left ventricular ejection fraction. This HF type predominantly affects women and the elderly with other co-morbidities, such as diabetes, hypertension, and overt volume status. Most of the current treatment strategies are based on morbidity benefits such as quality of life and reduction of clinical HF symptoms. Treatment of patients with HF with preserved ejection fraction displayed disappointing results from several large randomized controlled trials. The heterogeneity of HF with preserved ejection fraction, understood as complex syndrome, seems to be one of the primary reasons. Here, we present an overview of the current management strategies with available evidence and new therapeutic approach from drugs currently in clinical trials, which target diastolic dysfunction, chronotropic incompetence, and risk factor management. We provide an outline and interpretation of recent clinical trials that failed to improve outcome and survival in patients with HF with preserved ejection fraction.

GPCR signaling and cardiac function

G protein-coupled receptors (GPCRs), such as β-adrenergic and angiotensin II receptors, located in the membranes of all three major cardiac cell types, i.e. myocytes, fibroblasts and endothelial cells, play crucial roles in regulating cardiac function and morphology. Their importance in cardiac physiology and disease is reflected by the fact that, collectively, they represent the direct targets of over a third of the currently approved cardiovascular drugs used in clinical practice. Over the past few decades, advances in elucidation of their structure, function and the signaling pathways they elicit, specifically in the heart, have led to identification of an increasing number of new molecular targets for heart disease therapy. Here, we review these signaling modalities employed by GPCRs known to be expressed in the cardiac myocyte membranes and to directly modulate cardiac contractility. We also highlight drugs and drug classes that directly target these GPCRs to modulate cardiac function, as well as molecules involved in cardiac GPCR signaling that have the potential of becoming novel drug targets for modulation of cardiac function in the future.

Possible prevention of dialysis-requiring congestive heart failure by angiotensin-II receptor blockers in non-dialysis Japanese patients with Stage 5 chronic kidney disease

BACKGROUND

Preventive medications for dialysis-requiring congestive heart failure (CHF) in non-dialysis Japanese patients with Stage 5 chronic kidney disease (CKD) are unknown. Our aim was to explore which CKD medication was associated with a reduced prevalence of dialysis-requiring CHF in non-dialysis Japanese patients with Stage 5 CKD.

METHODS

The present multicenter, retrospective, cross-sectional study examined the association between CKD medications and the prevalence of dialysis-requiring CHF in non-dialysis Japanese patients with Stage 5 CKD.

RESULTS

There were 1536 Japanese Stage 5 CKD patients who satisfied our inclusion criteria. We had 309 (20.1%) patients whom had developed dialysis-requiring CHF and 940 patients (60.8%) whom had been using angiotensin-II receptor blockers (ARBs) before initiating dialysis. In our multivariate analysis, only ARB use was significantly associated with a lower risk of CHF (Odds ratio (OR): 0.680, 95% confidence interval (CI): 0.516-0.897; p = 0.0064), of the CKD treatments examined in this study.

CONCLUSIONS

We found that ARB use during the pre-dialysis period is associated with a lower prevalence of CHF in the non-dialysis Japanese patients with Stage 5 CKD, suggesting a possible prevention of dialysis-requiring CHF by ARBs, in non-dialysis Japanese patients with Stage 5 CKD.

Clinical characteristics of responders to treatment with tolvaptan in patients with acute decompensated heart failure: Importance of preserved kidney size

BACKGROUND

Recent clinical trials have demonstrated the efficacy of short-term treatment with tolvaptan, an oral vasopressin V2 receptor antagonist, in patients with heart failure. However, the response to tolvaptan varies among patients. The aim of this study was to determine factors associated with response to tolvaptan in patients with acute decompensated heart failure (ADHF).

METHODS

The Tolvaptan Registry, a prospective, observational, multicenter cohort study performed in Japan, aims to determine factors affecting the responsiveness of tolvaptan in patients with ADHF. We enrolled ADHF patients treated with tolvaptan and they were divided into two groups: responders and non-responders. Responders were defined as subjects who met all of the following three conditions: (1) increasing urine volume during a 24-hour period after the start of tolvaptan treatment; (2) improvement in New York Heart Association functional class; and (3) decrease in cardiothoracic ratio assessed by chest X-ray on day 3 of tolvaptan administration.

RESULTS

Among the 114 patients, treatment with tolvaptan improved three conditions of heart failure in more than half of all the cohorts (71 patients, 62%). As for baseline characteristics, estimated glomerular filtration rate, urine osmolality, and kidney size were significantly greater in responders than in non-responders. Multivariate logistic analysis revealed that kidney size was independently associated with responders (odds ratio: 1.083, p=0.001, 95% confidence interval 1.031-1.137).

CONCLUSIONS

The main clinical characteristic of responders to treatment with tolvaptan is that kidney size is preserved.

Angiotensin receptor-neprilysin inhibitors: clinical potential in heart failure and beyond

Heart failure remains a major concern across the globe as life expectancies and delivery of health care continue to improve. There has been a dearth of new developments in heart failure therapies in the last decade until last year, with the release of the results from the PARADIGM-HF Trial heralding the arrival of a promising new class of drug, ie, the angiotensin receptor-neprilysin inhibitor. In this review, we discuss the evolution of our incremental understanding of the neurohormonal mechanisms involved in the pathophysiology of heart failure, which has led to our success in modulating its various pathways. We start by examining the renin-angiotensin-aldosterone system, followed by the challenges of modulating the natriuretic peptide system. We then delve deeper into the pharmacology and mechanisms by which angiotensin receptor-neprilysin inhibitors achieve their significant cardiovascular benefits. Finally, we also consider the potential application of this new class of drug in other areas, such as heart failure with preserved ejection fraction, hypertension, patients with renal impairment, and following myocardial infarction.