Myocardial adeno-associated virus serotype 6-betaARKct gene therapy improves cardiac function and normalizes the neurohormonal axis in chronic heart failure.
ABSTRACT: The upregulation of G protein-coupled receptor kinase 2 in failing myocardium appears to contribute to dysfunctional beta-adrenergic receptor (betaAR) signaling and cardiac function. The peptide betaARKct, which can inhibit the activation of G protein-coupled receptor kinase 2 and improve betaAR signaling, has been shown in transgenic models and short-term gene transfer experiments to rescue heart failure (HF). This study was designed to evaluate long-term betaARKct expression in HF with the use of stable myocardial gene delivery with adeno-associated virus serotype 6 (AAV6).In HF rats, we delivered betaARKct or green fluorescent protein as a control via AAV6-mediated direct intramyocardial injection. We also treated groups with concurrent administration of the beta-blocker metoprolol. We found robust and long-term transgene expression in the left ventricle at least 12 weeks after delivery. betaARKct significantly improved cardiac contractility and reversed left ventricular remodeling, which was accompanied by a normalization of the neurohormonal (catecholamines and aldosterone) status of the chronic HF animals, including normalization of cardiac betaAR signaling. Addition of metoprolol neither enhanced nor decreased betaARKct-mediated beneficial effects, although metoprolol alone, despite not improving contractility, prevented further deterioration of the left ventricle.Long-term cardiac AAV6-betaARKct gene therapy in HF results in sustained improvement of global cardiac function and reversal of remodeling at least in part as a result of a normalization of the neurohormonal signaling axis. In addition, betaARKct alone improves outcomes more than a beta-blocker alone, whereas both treatments are compatible. These findings show that betaARKct gene therapy can be of long-term therapeutic value in HF.
Project description:G protein-coupled receptor kinase 2 (GRK2), which is markedly upregulated in failing human myocardium, has been implicated as a contributing factor or consequence of heart failure (HF). Importantly, cardiac-specific GRK2 knockout mice have recently proved the pathological nature of GRK2 in HF. Targeted inhibition of GRK2 is possible using a peptide inhibitor known as the ?ARKct, which has rescued several disparate small animal HF models. This study was designed to evaluate long-term ?ARKct expression in a clinically relevant large animal HF model, using stable myocardial gene delivery with adeno-associated virus serotype 6 (AAV6).A porcine model of HF subsequent to left ventricular (LV) myocardial infarction (MI) was used to study the effects of retrograde injection into the anterior interventricular vein of either AAV6.?ARKct or AAV6.luciferase as a control 2 weeks after MI. Echocardiography and LV hemodynamics were performed before and 6 weeks after gene transfer. Robust and long-term ?ARKct expression was found after AAV6-mediated delivery, leading to significant amelioration of LV haemodynamics and contractile function in HF pigs compared with AAV6.luciferase-treated control animals that showed a continued decline in cardiac function. Interestingly, the neurohormonal axis was virtually normalized in AVV6.?ARKct-treated HF animals, represented by reductions in plasma norepinephrine levels, whereas AAV6.luciferase-treated pigs showed further increases in plasma catecholamine levels. As a result, LV remodelling and foetal gene expression was reversed by AVV6.?ARKct gene therapy.These data--showing sustained amelioration of cardiac function in a post-MI pig HF model--demonstrate the therapeutic potential of ?ARKct gene therapy for HF.
Project description:The calcium pump SERCA2a (sarcoplasmic reticulum calcium ATPase 2a), which plays a central role in cardiac contraction, shows decreased expression in heart failure (HF). Increasing SERCA2a expression in HF models improves cardiac function. We used direct cardiac delivery of adeno-associated virus encoding human SERCA2a (AAV6-hSERCA2a) in HF and normal canine models to study safety, efficacy, and the effects of immunosuppression. Tachycardic-paced dogs received left ventricle (LV) wall injection of AAV6-hSERCA2a or solvent. Pacing continued postinjection for 2 or 6 weeks, until euthanasia. Tissue/serum samples were analyzed for hSERCA2a expression (Western blot) and immune responses (histology and AAV6-neutralizing antibodies). Nonpaced dogs received AAV6-hSERCA2a and were analyzed at 12 weeks; a parallel cohort received AAV-hSERCA2a and immunosuppression. AAV-mediated cardiac expression of hSERCA2a peaked at 2 weeks and then declined (to ~50%; p<0.03, 6 vs. 2 weeks). LV end diastolic and end systolic diameters decreased in 6-week dogs treated with AAV6-hSERCA2a (p<0.05) whereas LV diameters increased in control dogs. Dogs receiving AAV6-hSERCA2a developed neutralizing antibodies (titer ≥1:120) and cardiac cellular infiltration. Immunosuppression dramatically reduced immune responses (reduced inflammation and neutralizing antibody titers <1:20), and maintained hSERCA2a expression. Thus cardiac injection of AAV6-hSERCA2a promotes local hSERCA2a expression and improves cardiac function. However, the hSERCA2a protein level is reduced by host immune responses. Immunosuppression alleviates immune responses and sustains transgene expression, and may be an important adjuvant for clinical gene therapy trials.
Project description:A key feature of chronic heart failure (HF) is the sustained activation of endogenous neurohormonal systems in response to impaired cardiac pumping and/or filling properties. The clinical use of neurohormonal blockers has revolutionised the care of HF patients over the past three decades. Drug therapy that is active against imbalance in both the autonomic and renin-angiotensin-aldosterone systems consistently reduces morbidity and mortality in chronic HF with reduced left ventricular ejection fraction and in sinus rhythm. This article provides an assessment of the major neurohormonal systems and their therapeutic blockade in patients with chronic HF.
Project description:In patients with conduction abnormalities or left ventricle (LV) dysfunction the use of ?-blockers for post cardiac surgery rhythm control is difficult and controversial, with a paucity of information about other drugs such ivabradine used postoperatively. The objective of this study was to compare the efficacy and safety of ivabradine versus metoprolol used perioperatively in cardiac surgery patients with conduction abnormalities or LV systolic dysfunction.This was an open-label, randomized clinical trial enrolling 527 patients with conduction abnormalities or LV systolic dysfunction undergoing coronary artery bypass grafting or valvular replacement, randomized to take ivabradine or metoprolol, or metoprolol plus ivabradine. The primary endpoints were the composites of 30-day mortality, in-hospital atrial fibrillation (AF), in-hospital three-degree atrioventricular block and need for pacing, in-hospital worsening heart failure (HF; safety endpoints), duration of hospital stay and immobilization and the above endpoint plus in-hospital bradycardia, gastrointestinal symptoms, sleep disturbances, cold extremities (efficacy plus safety endpoint).Heart rate reduction and prevention of postoperative AF or tachyarrhythmia with combined therapy was more effective than with metoprolol or ivabradine alone during the immediate postoperative management of cardiac surgery patients. In the Ivabradine group, the frequency of early postoperative pacing and HF worsening was smaller than in the Metoprolol group and in combined therapy group. The frequency of primary combined endpoint was lower in the combined Ivabradine + Metoprolol group compared with the monotherapy groups.Considering efficacy and safety, the cardiac rhythm reduction after open heart surgery in patients with conduction abnormalities or LV dysfunction with ivabradine plus metoprolol emerged as the best treatment in this trial.
Project description:cAMP/protein kinase (PK)A activation represents a key signaling mechanism for neurohormonal stimulation of diversified physiological processes. Using real-time, fluorescence resonance energy transfer-based imaging of PKA activity in neonatal cardiac myocytes, we report that sustained activation of PKA induced by beta-adrenoceptor (betaAR) dictates signaling propagation for substrate phosphorylation and myocyte contraction. Activation of betaARs in wild-type myocytes induces strong and sustained PKA activities, which are rapidly attenuated on washing away agonist or adding antagonist to the cells. The sustained PKA activities promote signaling propagation to the sarcoplasmic reticulum for phosphorylation of phospholamban and increases in myocyte contraction. Addition of antagonist after betaAR stimulation significantly attenuates PKA phosphorylation of phospholamban and rapidly reduces contraction rate increases. Moreover, stimulation of beta(1)AR subtype induces PKA activities similar to those in wild-type cells. In contrast, stimulation of beta(2)AR subtype induces strong initial activation of PKA similar to those induced by beta(1)AR; however, the activities are rapidly decreased to baseline levels. The transient PKA activities are sufficient for phosphorylation of the overexpressed beta(2)ARs under agonist stimulation, but not phospholamban. Further analysis reveals that phosphodiesterase 4 is the major family that shapes PKA activities under betaAR stimulation. Inhibition of phosphodiesterase 4 extends beta(2)AR-induced PKA activities, promotes PKA phosphorylation of phospholamban, and ultimately enhances myocyte contraction responses. Together, our data have revealed insights into kinetics of PKA activities in signaling propagation under neurohormonal stimulation.
Project description:Right heart failure is the major cause of death in Pulmonary Artery Hypertension (PAH) patients but is not a current, specific therapeutic target. Pre-clinical studies have shown that adrenoceptor blockade can improve cardiac function but the mechanisms of action within right ventricular (RV) myocytes are unknown. We tested whether the ?1-adrenoceptor blocker metoprolol could improve RV myocyte function in an animal model of PAH, by attenuating adverse excitation-contraction coupling remodeling. PAH with RV failure was induced in rats by monocrotaline injection. When PAH was established, animals were given 10?mg/kg/day metoprolol (MCT?+?BB) or vehicle (MCT). The median time to the onset of heart failure signs was delayed from 23?days (MCT), to 31?days (MCT?+?BB). At 23?±?1?days post-injection, MCT?+?BB showed improved in vivo cardiac function, measured by echocardiography. RV hypertrophy was reduced despite persistent elevated afterload. RV myocyte contractility during field stimulation was improved at higher pacing frequencies in MCT?+?BB. Preserved t-tubule structure, more uniform evoked Ca2+ release, increased SERCA2a expression and faster ventricular repolarization (measured in vivo by telemetry) may account for the improved contractile function. Sarcoplasmic reticulum Ca2+ overload was prevented in MCT?+?BB myocytes resulting in fewer spontaneous Ca2+ waves, with a lower pro-arrhythmic potential. Our novel finding of attenuation of defects in excitation contraction coupling by ?1-adrenoceptor blockade with delays in the onset of HF, identifies the RV as a promising therapeutic target in PAH. Moreover, our data suggest existing therapies for left ventricular failure may also be beneficial in PAH induced RV failure.
Project description:Clinical efficacy of metoprolol combined with irbesartan and hydrochlorothiazide and non-invasive ventilator in the emergency treatment of patients with severe heart failure (HF) was investigated. A retrospective analysis of the medical records of 124 patients with severe HF admitted to Binzhou Medical University Hospital from May 2012 to August 2016 was performed. Among them, 78 patients who were treated with metoprolol combined with irbesartan and hydrochlorothiazide and non-invasive ventilator for emergency treatment were enrolled into the Research Group, while the Control Group consisted of 46 patients treated with routine medical treatment. Echocardiographic parameters, 6-minute walking test results, the efficacy of the emergency treatment, cardiac function grading, left ventricular ejection fraction (LVEF) and brain natriuretic peptide (BNP) levels were compared between the two groups. After the emergency treatment, the echocardiographic indexes of both groups increased to different extents (P<0.05). Compared with the results before, patients of both groups walked longer within six minutes after the emergency treatment (P<0.05). After the emergency treatment, the BNP expression levels in the two groups decreased to different degrees (P<0.05). After a 7-day emergency treatment, the efficiency rate of treatment of the Research Group was higher than that of the Control Group (P<0.05). The method is helpful for the recovery of respiratory function, for relieving symptoms in short time, improving cardiac function and promising high safety, using metoprolol and irbesartan and hydrochlorothiazide combined with non-invasive ventilator had satisfactory clinical efficacy in the emergency treatment of patients with severe heart failure and is thus worthy of clinical promotion.
Project description:Low levels of the molecular inotrope S100A1 are sufficient to rescue post-ischemic heart failure (HF). As a prerequisite to clinical application and to determine the safety of myocardial S100A1 DNA-based therapy, we investigated the effects of high myocardial S100A1 expression levels on the cardiac contractile function and occurrence of arrhythmia in a preclinical large animal HF model. At 2 weeks after myocardial infarction domestic pigs presented significant left ventricular (LV) contractile dysfunction. Retrograde application of AAV6-S100A1 (1.5 × 10(13) tvp) via the anterior cardiac vein (ACV) resulted in high-level myocardial S100A1 protein peak expression of up to 95-fold above control. At 14 weeks, pigs with high-level myocardial S100A1 protein overexpression did not show abnormalities in the electrocardiogram. Electrophysiological right ventricular stimulation ruled out an increased susceptibility to monomorphic ventricular arrhythmia. High-level S100A1 protein overexpression in the LV myocardium resulted in a significant increase in LV ejection fraction (LVEF), albeit to a lesser extent than previously reported with low S100A1 protein overexpression. Cardiac remodeling was, however, equally reversed. High myocardial S100A1 protein overexpression neither increases the occurrence of cardiac arrhythmia nor causes detrimental effects on myocardial contractile function in vivo. In contrast, this study demonstrates a broad therapeutic range of S100A1 gene therapy in post-ischemic HF using a preclinical large animal model.
Project description:AbstractBackgroundIsolated left ventricular apical hypoplasia (ILVAH) is a rare congenital cardiac abnormality, which might result in severe symptomatic heart failure (HF) with pulmonary hypertension, atrial fibrillation (AF), or malignant ventricular tachycardia in adults.Case summaryA 32-years-old man presented with exertional dyspnoea New York Heart Association Class II and persistent AF. Echocardiography and cardiac magnetic resonance showed the presence of (i) spherical remodelling of the left ventricle (LV) with impaired contractile function (three-dimensional ejection fraction, EF 32%); (ii) substitution of apical myocardium by fatty tissue; (iii) abnormal origin of a papillary muscle network; and (iv) an elongated right ventricle, compatible with ILVAH. In addition, non-compacted endomyocardial layer of the LV was observed. Because of a high risk of sudden cardiac death in symptomatic HF patients with reduced EF, an implantable cardioverter-defibrillator was placed which followed by pulmonary vein isolation. After the procedures and restoration of sinus rhythm, the patient demonstrated improvement in HF symptoms and exercise tolerance. This was accompanied by an enhancement of left and right ventricular systolic function by echocardiography. At 6-month, 1, and 2-year follow-up the clinical conditions of the patient and echocardiographic findings remained stable.DiscussionA rare combination of ILVAH and left ventricular myocardium non-compaction was observed in this young adult who presented with symptomatic HF and persistent AF. The use of consecutive invasive cardiac procedures leads to restoration of sinus rhythm, the improvement of myocardial contractility and clinical manifestation of HF.
Project description:Vasopressin type 1A receptor (V1AR) expression is elevated in chronic human heart failure (HF) and contributes to cardiac dysfunction in animal models, in part via reduced ?-adrenergic receptor (?AR) responsiveness. Although cardiac V1AR overexpression and V1AR stimulation are each sufficient to decrease ?AR activity, it is unknown whether V1AR inhibition conversely augments ?AR responsiveness. Further, although V1AR has been shown to contribute to chronic progression of HF, its impact on cardiac function following acute ischaemic injury has not been reported. Using V1AR knockout (V1AR KO) mice we assessed the impact of V1AR deletion on cardiac contractility at baseline and following ischaemic injury, ?AR sensitivity and cardiomyocyte responsiveness to ?AR stimulation. Strikingly, baseline cardiac contractility was enhanced in V1AR KO mice and they experienced a greater loss in contractile function than control mice following acute ischaemic injury, although the absolute levels of cardiac dysfunction and survival rates did not differ. Enhanced cardiac contractility in V1AR KO mice was associated with augmented ?-blocker sensitivity, suggesting increased basal ?AR activity, and indeed levels of left ventricular cAMP, as well as phospholamban (PLB) and cardiac troponin I (cTnI) phosphorylation were elevated compared with control mice. At the cellular level, myocytes isolated from V1AR KO mice demonstrated increased responsiveness to ?AR stimulation consistent with the finding that acute pharmacological V1AR inhibition enhanced ?AR-mediated contractility in control myocytes. Therefore, although V1AR deletion does not protect the heart from the rapid development of cardiac dysfunction following acute ischaemic injury, its effects on ?AR activity suggest that acute V1AR inhibition could be utilized to promote myocyte contractile performance.