Haemodynamic effects, safety, and pharmacokinetics of human stresscopin in heart failure with reduced ejection fraction

The urocortin peptides: biological relevance and laboratory aspects of UCN3 and its receptor

The urocortins are polypeptides belonging to the corticotropin-releasing hormone family, known to modulate stress responses in mammals. Stress, whether induced physically or psychologically, is an underlying cause or consequence of numerous clinical syndromes. Identifying biological markers associated with the homeostatic regulation of stress could provide a clinical laboratory approach for the management of stress-related disorders. The neuropeptide, urocortin 3 (UCN3), and the corticotropin-releasing hormone receptor 2 (CRHR2) constitute a regulatory axis known to mediate stress homeostasis. Dysregulation of this peptide/receptor axis is believed to play a role in several clinical conditions including post-traumatic stress, sleep apnea, cardiovascular disease, and other health problems related to stress. Understanding the physiology and measurement of the UCN3/CRHR2 axis is important for establishing a viable clinical laboratory diagnostic. In this article, we focus on evidence supporting the role of UCN3 and its receptor in stress-related clinical syndromes. We also provide insight into the measurements of UCN3 in blood and urine. These potential biomarkers provide new opportunities for clinical research and applications of laboratory medicine diagnostics in stress management.

Urocortin 2 Gene Transfer for Systolic and Diastolic Dysfunction Due to Chronically Increased Left Ventricular Pressure

We used transverse aortic constriction (TAC) in mice to test the hypothesis that urocortin 2 (Ucn2) gene transfer would increase left ventricular (LV) systolic and diastolic function in the pressure-stressed LV. Three groups were studied: (1) control mice (no TAC); (2) mice that received saline 6 weeks after TAC; and (3) mice that received Ucn2 gene transfer 6 weeks after TAC, using adeno-associated virus 8 encoding murine Ucn2 (AAV8.mUcn2; 2 × 1013 genome copies (gc)/kg, i.v. per mouse). Echocardiography was performed 6 and 12 weeks after TAC. In terminal studies 12 weeks after TAC, rates of LV pressure development and decay and Tau were measured, and LV cardiac myocytes (CMs) were isolated and cytosolic Ca2+ transients and sarcomere shortening rates recorded. Reverse transcription polymerase chain reaction and immunoblotting were used to measure key proteins in LV samples. A CM cell line (HL-1) was used to explore mechanisms. Concentric LV hypertrophy was evident on echocardiography 6 weeks after TAC. Twelve weeks after TAC, LV ejection fraction (EF) was higher in mice that received Ucn2 gene transfer (TAC-saline: 65% ± 3%; TAC-Ucn2: 75% ± 2%; p = 0.01), as was LV peak +dP/dt (1.9-fold increase; p = 0.001) and LV peak -dP/dt (1.7-fold increase; p = 0.017). Tau was more rapid (23% reduction, p = 0.02), indicating improved diastolic function. The peak rates of sarcomere shortening (p = 0.002) and lengthening (p = 0.002) were higher in CMs from TAC-Ucn2 mice, and Tau was reduced (p = 0.001). LV (Ser-16) phosphorylation of phospholamban (PLB) was increased in TAC-Ucn2 mice (p = 0.025), and also was increased in HL-1 cells treated with angiotensin II to induce hypertrophy and incubated with Ucn2 peptide (p = 0.001). Ucn2 gene transfer in TAC-induced heart failure with preserved ejection fraction increased cardiac function in the intact LV and provided corresponding benefits in CMs isolated from study animals, including increased myofilament Ca2+ sensitivity during contraction. The mechanism includes enhanced CM Ca2+ handling associated with increased (Ser-16)-PLB.

Urocortins as biomarkers in cardiovascular disease

The urocortins (Ucns) belong to the corticotropin-releasing factor (CRF) family of peptides and have multiple effects within the central nervous and the cardiovascular systems. With growing evidence indicating significant cardioprotective properties and cardiovascular actions of these peptides, the question arises as to whether the plasma profiles of the Ucns are altered in pathologic settings. While reports have shown conflicting results and findings have not been corroborated in multiple independent cohorts, it seems likely that plasma Ucn concentrations are elevated in multiple cardiovascular conditions. The degree of increase and accurate determination of circulating values of the Ucns requires further validation.

Urocortin Role in Ischemia Cardioprotection and the Adverse Cardiac Remodeling

Despite the considerable progress in strategies of myocardial protection, ischemic heart diseases (IHD) and consequent heart failure (HF) remain the main cause of mortality worldwide. Several procedures are used routinely to guarantee the prompt and successful reestablishment of blood flow to preserve the myocardial viability of infarcted hearts from ischemia injuries. However, ischemic heart reperfusion/revascularization triggers additional damages that occur when oxygen-rich blood re-enters the vulnerable myocardial tissue, which is a phenomenon known as ischemia and reperfusion (I/R) syndrome. Complications of I/R injuries provoke the adverse cardiac remodeling, involving inflammation, mishandling of Ca²⁺ homeostasis, apoptotic genes activation, cardiac myocytes loss, etc., which often progress toward HF. Therefore, there is an urgent need to develop new cardioprotective therapies for IHD and HF. Compelling evidence from animal studies and pilot clinical trials in HF patients suggest that urocortin (Ucn) isoforms, which are peptides associated with stress and belonging to the corticotropin releasing factor family, have promising potential to improve cardiovascular functions by targeting many signaling pathways at different molecular levels. This review highlights the current knowledge on the role of urocortin isoforms in cardioprotection, focusing on its acute and long-term effects.

Advances in therapeutic peptides targeting G protein-coupled receptors

Dysregulation of peptide-activated pathways causes a range of diseases, fostering the discovery and clinical development of peptide drugs. Many endogenous peptides activate G protein-coupled receptors (GPCRs) - nearly 50 GPCR peptide drugs have been approved to date, most of them for metabolic disease or oncology, and more than 10 potentially first-in-class peptide therapeutics are in the pipeline. The majority of existing peptide therapeutics are agonists, which reflects the currently dominant strategy of modifying the endogenous peptide sequence of ligands for peptide-binding GPCRs. Increasingly, novel strategies are being employed to develop both agonists and antagonists, to both introduce chemical novelty and improve drug-like properties. Pharmacodynamic improvements are evolving to allow biasing ligands to activate specific downstream signalling pathways, in order to optimize efficacy and reduce side effects. In pharmacokinetics, modifications that increase plasma half-life have been revolutionary. Here, we discuss the current status of the peptide drugs targeting GPCRs, with a focus on evolving strategies to improve pharmacokinetic and pharmacodynamic properties.

Urocortin 2 Gene Transfer Improves Heart Function in Aged Mice

Prevalence of left ventricular (LV) systolic and diastolic dysfunction increases with aging. We previously reported that urocortin 2 (Ucn2) gene transfer increases heart function in mice with heart failure with reduced ejection fraction. Here, we test the hypotheses that (1) Ucn2 gene transfer will increase LV function in aged mice and that (2) Ucn2 gene transfer given in early life will prevent age-related LV dysfunction. Nineteen-month-old (treatment study) and 3-month-old (prevention study) mice received Ucn2 gene transfer or saline. LV function was examined 3-4 months (treatment study) or 20 months (prevention study) after Ucn2 gene transfer or saline injection. In both the treatment and prevention strategies, Ucn2 gene transfer increased ejection fraction, reduced LV volume, increased LV peak -dP/dt and peak +dP/dt, and reduced global longitudinal strain. Ucn2 gene transfer-in both treatment and prevention strategies-was associated with higher levels of LV SERCA2a protein, reduced phosphorylation of LV CaMKIIa, and reduced LV α-skeletal actin mRNA expression (reflecting reduced cardiac stress). In conclusion, Ucn2 gene transfer restores normal cardiac function in mice with age-related LV dysfunction and prevents development of LV dysfunction.

Pharmaceutical Treatment for Heart Failure

Heart failure (HF) is defined as a clinical syndrome resulting from structural or functional impairment of ventricular fillings or ejections of blood. Currently, HF is divided into three groups which include HF with reduced ejection fraction (HFrEF), HF with preserved ejection fraction (HFpEF) and HF with midrange EF (HFmrEF). Even though major advances have been made in treating HFrEF during the past decades, heart failure is a fatal disease. In this review, we briefly summarize the current advances in pharmaceutical managements for heart failure, which includes drugs used in acute heart failure as well as those that prevent heart failure progression, in each category major clinical trials are also described. In addition, information about some of potential new drugs are also mentioned. Traditional Chinese medicine also shows its potential in treating HF, and we are still lack of medicine to treat HFpEF.

Modified UCN2 Peptide Acts as an Insulin Sensitizer in Skeletal Muscle of Obese Mice

The neuropeptide urocortin 2 (UCN2) and its receptor corticotropin-releasing hormone receptor 2 (CRHR2) are highly expressed in skeletal muscle and play a role in regulating energy balance and glucose metabolism. We investigated a modified UCN2 peptide as a potential therapeutic agent for the treatment of obesity and insulin resistance, with a specific focus on skeletal muscle. High-fat-fed mice (C57BL/6J) were injected daily with a PEGylated UCN2 peptide (compound A) at 0.3 mg/kg subcutaneously for 14 days. Compound A reduced body weight, food intake, whole-body fat mass, and intramuscular triglycerides compared with vehicle-treated controls. Furthermore, whole-body glucose tolerance was improved by compound A treatment, with increased insulin-stimulated Akt phosphorylation at Ser⁴⁷³ and Thr³⁰⁸ in skeletal muscle, concomitant with increased glucose transport into extensor digitorum longus and gastrocnemius muscle. Mechanistically, this is linked to a direct effect on skeletal muscle because ex vivo exposure of soleus muscle from chow-fed lean mice to compound A increased glucose transport and insulin signaling. Moreover, exposure of GLUT4-Myc-labeled L6 myoblasts to compound A increased GLUT4 trafficking. Our results demonstrate that modified UCN2 peptides may be efficacious in the treatment of type 2 diabetes by acting as an insulin sensitizer in skeletal muscle.

Urocortin 2 Gene Transfer Reduces the Adverse Effects of a Western Diet on Cardiac Function in Mice

Diabetes mellitus is associated with increased risk of heart failure. It has been previously demonstrated in mice that a single injection of adeno-associated virus 8 encoding urocortin 2 (AAV8.UCn2) increases glucose disposal in models of insulin resistance and improves the function of the failing heart. The present study tested the hypothesis that UCn2 gene transfer would reduce diabetes-related left ventricular (LV) dysfunction. Eight-week-old C57BL6 male mice were fed a Western diet (WD; 45% fat, 35% carbohydrate) for 40 weeks. At week 30, they received saline or AAV8.UCn2 (2 × 10¹³ genome copies/kg) via intravenous injection. Ten weeks after gene transfer, fasting blood glucose, glucose tolerance, and cardiac function were measured via echocardiography and in vivo measurement of LV contractile function, and the results were compared to those of mice fed normal chow (NC; 10% fat; 70% carbohydrate). The contents of key LV signaling proteins were also measured to probe mechanisms. WD increased 12 h fasting glucose (WD: 190 ± 11 mg/dL, n = 8; NC: 105 ± 12 mg/dL, n = 7; p = 0.0004). WD tended to reduce LV peak +dP/dt (p = 0.08) and LV peak -dP/dt (p = 0.05). LV ejection fraction was unchanged. Among WD-fed mice, UCn2 gene transfer reduced 12 h fasting glucose (WD-UCn2: 149 ± 6 mg/dL, n = 8; WD-Saline: 190 ± 11 mg/dL, n = 8; p = 0.012), increased LV peak +dP/dt (p < 0.001) and LV peak -dP/dt (p = 0.013), and reduced Tau (p < 0.02), indicating beneficial effects on systolic and diastolic LV function. In addition, among WD-fed mice, UCn2 gene transfer increased LV ejection fraction (p < 0.005) and the velocity of circumferential fiber shortening (p = 0.0005). Finally, a reduction was seen in fatty infiltration of the liver in WD-fed mice that had received UCn2 gene transfer. LV samples from WD-UCn2 mice showed increased phosphorylation of the protein kinase A catalytic domain (p = 0.03). In conclusion, UCn2 gene transfer increased LV systolic and diastolic function and reduced blood glucose in mice with diabetes-related LV dysfunction, indicating that UCn2 gene transfer may be of potential therapeutic benefit.

Urocortin 3 Gene Transfer Increases Function of the Failing Murine Heart

Peptide infusions of peptides the corticotropin releasing factor family, including urocortin 2, stresscopin, and urocortin 3 (UCn3), have favorable acute effects in clinical heart failure (HF), but their short half-lives make them unsuitable for chronic therapy. This study asked whether UCn3 gene transfer, which provides sustained elevation of plasma UCn3 levels, increases the function of the failing heart. HF was induced by transmural left ventricular (LV) cryoinjury in mice. LV function was assessed 3 weeks later by echocardiography. Those with ejection fractions (EF) <40% received intravenous saline or intravenous adeno-associated virus type-8 encoding murine UCn3 (AAV8.mUCn3; 1.9 × 10¹³ genome copies/kg). Five weeks after randomization, repeat echocardiography, assessment of LV function (+dP/dt, -dP/dt), and quantification of Ca²⁺ transients and sarcomere shortening in isolated cardiac myocytes were conducted, and assessment of LV Ca²⁺ handling and stress proteins was performed. Three weeks after myocardial infarction, prior to treatment, EFs were reduced (mean 31%, from 63% in sham-operated animals). Mice randomized to receive UCn3 gene transfer showed increased plasma UCn3 (from 0.1 ± 0.01 ng/mL in the saline group to 5.6 ± 1.1 ng/mL; n = 12 each group; p < 0.0001). Compared to mice that received saline, UCn3 gene transfer was associated with higher values for EF (p = 0.0006); LV +dP/dt (p < 0.0001), and LV -dP/dt (p < 0.0001). Cardiac myocytes from mice that received UCn3 gene transfer showed higher peak Ca²⁺ transients (p = 0.0005), lower time constant of cytosolic Ca²⁺ decline (tau, p < 0.0001), and higher rates of sarcomere shortening (+dL/dt, p = 0.03) and lengthening (-dL/dt, p = 0.04). LV samples from mice that received UCn3 gene transfer contained higher levels of SERCA2a (p = 0.0004 vs. HF) and increased amounts of phosphorylated troponin I (p = 0.04 vs. HF). UCn3 gene transfer is associated with improved Ca²⁺ handling and LV function in mice with HF and reduced EF.

Hormone treatments in congestive heart failure

The common ultimate pathological feature for all cardiovascular diseases, congestive heart failure (CHF), is now considered as one of the main public health burdens that is associated with grave implications. Neurohormonal systems play a critical role in cardiovascular homeostasis, pathophysiology, and cardiovascular diseases. Hormone treatments such as the newly invented dual-acting drug valsartan/sacubitril are promising candidates for CHF, in addition to the conventional medications encompassing beta receptor blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and mineralocorticoid receptor antagonists. Clinical trials also indicate that in CHF patients with low insulin-like growth factor-1 or low thyroid hormone levels, supplemental treatment with growth hormone or thyroid hormone seems to be cardioprotective; and in CHF patients with volume overload the vasopressin antagonists can relieve the symptoms superior to loop diuretics. Furthermore, a combination of selective glucocorticoid receptor agonist and mineralocorticoid receptor antagonist may be used in patients with diuretic resistance. Finally, the potential cardiovascular efficacy and safety of incretin-based therapies, testosterone or estrogen supplementation needs to be prudently evaluated in large-scale clinical studies. In this review, we briefly discuss the therapeutic effects of several key hormones in CHF.

Effects of Urocortin 2 Versus Urocortin 3 Gene Transfer on Left Ventricular Function and Glucose Disposal

UCn2 and UCn3 peptides have recently been infused to treat patients with heart failure (HF) but are limited by their short half-lives. A 1-time intravenous injection of virus vectors encoding UCn2 or UCn3 provided sustained increases in plasma concentrations of the peptides. This was associated with increases in both systolic and diastolic left ventricular (LV) function, mediated by increased LV SERCA2a expression and Ca2+ handling. UCn2, but not UCn3, gene transfer reduced fasting glucose and increased glucose disposal. These findings support UCn2 and UCn3 gene transfer as potential treatments for HF and indicate that UCn2 may be an optimal selection in patients with diabetes and HF.

New Medications in the Treatment of Acute Decompensated Heart Failure

Acute decompensated heart failure is a sudden worsening of heart failure symptoms, typically resulting in peripheral edema and dyspnea as a result of pulmonary congestion. Acute decompensated heart failure is responsible for over 1 million hospitalizations every year. Current pharmacologic therapy is limited in its options. Despite an improved survival rate, statistic still suggests that about 50% of patients die within 5 years of diagnosis. New pharmacologic agents aim to improve efficacy by targeting previously unexplored physiological pathways.

Epidemiology, pathophysiology, and in-hospital management of pulmonary edema: data from the Romanian Acute Heart Failure Syndromes registry

AIM

The objective of this study was to evaluate the clinical presentation, inpatient management, and in-hospital outcome of patients hospitalized for acute heart failure syndromes (AHFS) and classified as pulmonary edema (PE).

METHODS

The Romanian Acute Heart Failure Syndromes (RO-AHFS) study was a prospective, national, multicenter registry of all consecutive patients admitted with AHFS over a 12-month period. Patients were classified at initial presentation by clinician-investigators into the following clinical profiles: acute decompensated HF, cardiogenic shock, PE, right HF, or hypertensive HF.

RESULTS

RO-AHFS enrolled 3224 patients and 28.7% (n = 924) were classified as PE. PE patients were more likely to present with pulmonary congestion, tachypnea, tachycardia, and elevated systolic blood pressure and less likely to have peripheral congestion and body weight increases. Mechanical ventilation was required in 8.8% of PE patients. PE patients received higher doses (i.e. 101.4 ± 27.1 mg) of IV furosemide for a shorter duration (i.e. 69.3 ± 22.3 hours). Vasodilators were given to 73.6% of PE patients. In-hospital all-cause mortality (ACM) in PE patients was 7.4%, and 57% of deaths occurred on day one. Increasing age, concurrent acute coronary syndromes, life-threatening ventricular arrhythmias, elevated BUN, left bundle branch block, inotrope therapy, and requirement for invasive mechanical ventilation were independent risk factors for ACM.

CONCLUSIONS

In this national registry, the PE profile was found to be a high-acuity clinical presentation with distinctive treatment patterns and a poor short-term prognosis. Advances in the management of PE may necessitate both the development of novel targeted therapies as well as systems-based strategies to identify high-risk patients early in their course.

One-time injection of AAV8 encoding urocortin 2 provides long-term resolution of insulin resistance

Using mice rendered insulin resistant with high fat diets (HFD), we examined blood glucose levels and insulin resistance after i.v. delivery of an adeno-associated virus type 8 encoding murine urocortin 2 (AAV8.UCn2). A single i.v. injection of AAV8.UCn2-normalized blood glucose and glucose disposal within weeks, an effect that lasted for months. Hyperinsulinemic-euglycemic clamps showed reduced plasma insulin, increased glucose disposal rates, and increased insulin sensitivity following UCn2 gene transfer. Mice with corticotropin-releasing hormone type 2-receptor deletion that were rendered insulin resistant by HFD showed no improvement in glucose disposal after UCn2 gene transfer, indicating that the effect requires UCn2's cognate receptor. We also demonstrated increased glucose disposal after UCn2 gene transfer in db/db mice, a second model of insulin resistance. UCn2 gene transfer reduced fatty infiltration of the liver in both models of insulin resistance. UCn2 increases Glut4 translocation to the plasma membrane in skeletal myotubes in a manner quantitatively similar to insulin, indicating a mechanism through which UCn2 operates to increase insulin sensitivity. UCn2 gene transfer, in a dose-dependent manner, is insulin sensitizing and effective for months after a single injection. These findings suggest a potential long-term therapy for clinical type-2 diabetes.

Cardiovascular effects of urocortin 2 and urocortin 3 in patients with chronic heart failure

AIMS

Urocortin 2 and urocortin 3 may play a role in the pathophysiology of heart failure and are emerging therapeutic targets. We aimed to examine the local and systemic cardiovascular effects of urocortin 2 and urocortin 3 in healthy subjects and patients with heart failure.

METHODS

Patients with heart failure (n = 8) and age and gender-matched healthy subjects (n = 8) underwent bilateral forearm arterial blood flow measurement using forearm venous occlusion plethysmography during intra-arterial infusions of urocortin 2 (3.6-36 pmol min(-1) ), urocortin 3 (360-3600 pmol min(-1) ) and substance P (2-8 pmol min(-1) ). Heart failure patients (n = 9) and healthy subjects (n = 7) underwent non-invasive impedance cardiography during incremental intravenous infusions of sodium nitroprusside (573-5730 pmol kg(-1)  min(-1) ), urocortin 2 (36-360 pmol min(-1) ), urocortin 3 (1.2-12 nmol min(-1) ) and saline placebo.

RESULTS

Urocortin 2, urocortin 3 and substance P induced dose-dependent forearm arterial vasodilatation in both groups (P < 0.05 for both) with no difference in magnitude of vasodilatation between patients and healthy subjects. During systemic intravenous infusions, urocortin 3 increased heart rate and cardiac index and reduced mean arterial pressure and peripheral vascular resistance index in both groups (P < 0.01 for all). Urocortin 2 produced similar responses to urocortin 3, although increases in cardiac index and heart rate were only significant in heart failure (P < 0.05) and healthy subjects (P < 0.001), respectively.

CONCLUSION

Urocortins 2 and 3 cause vasodilatation, reduce peripheral vascular resistance and increase cardiac output in both health and disease. These data provide further evidence to suggest that urocortins 2 and 3 continue to hold promise for the treatment of heart failure.

Emerging Therapies for Acute and Chronic Heart Failure

Although the period from 1953 to 2001 resulted in the approval of more than 30 medications currently used to treat heart failure (HF), few novel drugs have been approved in the last decade. However, the investigational pipeline for HF medications once again appears promising. In patients with chronic heart failure with reduced ejection fraction (HFrEF), ivabradine and valsartan/sucubitril (LCZ696) were recently approved by the US Food and Drug Administration. Both agents have been shown to reduce the risk of cardiovascular death and HF hospitalization. In the treatment of acute HF, serelaxin and ularitide are the farthest along in development. Both agents have demonstrated favorable effects on surrogate end points and preliminary data suggest a possible mortality benefit with serelaxin. Consequently, phase 3 trials are ongoing to evaluate the effect of serelaxin and ularitide on clinical outcomes. Given the poor history of recent investigational acute HF drugs that have advanced to phase 3/4 studies, enthusiasm for both serelaxin and ularitide must be tempered until these trials are completed.

Comparative effects of urocortins and stresscopin on cardiac myocyte contractility

RATIONALE

There is a current need for the development of new therapies for patients with heart failure.

OBJECTIVE

We test the effects of members of the corticotropin-releasing factor (CRF) family of peptides on myocyte contractility to validate them as potential heart failure therapeutics.

METHODS AND RESULTS

Adult feline left ventricular myocytes (AFMs) were isolated and contractility was assessed in the presence and absence of CRF peptides Urocortin 2 (UCN2), Urocortin 3 (UCN3), Stresscopin (SCP), and the β-adrenergic agonist isoproterenol (Iso). An increase in fractional shortening and peak Ca(2+) transient amplitude was seen in the presence of all CRF peptides. A decrease in Ca(2+) decay rate (Tau) was also observed at all concentrations tested. cAMP generation was measured by ELISA in isolated AFMs in response to the CRF peptides and Iso and significant production was seen at all concentrations and time points tested.

CONCLUSIONS

The CRF family of peptides effectively increases cardiac contractility and should be evaluated as potential novel therapeutics for heart failure patients.

Intravenous AAV8 Encoding Urocortin-2 Increases Function of the Failing Heart in Mice

Urocortin-2 (UCn2) peptide infusion increases cardiac function in patients with heart failure, but chronic peptide infusion is cumbersome, is costly, and provides only short-term benefits. Gene transfer would circumvent these shortcomings. We previously showed that a single intravenous (IV) injection of AAV8.UCn2 increases plasma UCn2 and left ventricular (LV) systolic and diastolic function for at least 7 months in normal mice. Here we test the hypothesis that IV delivery of AAV8.UCn2 increases function of the failing heart. Myocardial infarction (MI, by coronary ligation) was used to induce heart failure, which was assessed by echocardiography 3 weeks after MI. Mice with LV ejection fraction (EF) <25% received IV delivery of AAV8.UCn2 (5×10¹¹ gc) or saline, and 5 weeks later echocardiography showed increased LV EF in mice that received UCn2 gene transfer (p=0.01). In vivo physiological studies showed a 2-fold increase in peak rate of LV pressure development (LV +dP/dt; p<0.0001) and a 1.6-fold increase in peak rate of LV pressure decay (LV −dP/dt; p=0.0007), indicating increased LV systolic and diastolic function in treated mice. UCn2 gene transfer was associated with increased peak systolic Ca²⁺ transient amplitude and rate of Ca²⁺ decline and increased SERCA2a expression. In addition, UCn2 gene transfer reduced Thr286 phosphorylation of Cam kinase II, and increased expression of cardiac myosin light chain kinase, findings that would be anticipated to increase function of the failing heart. We conclude that a single IV injection of AAV8.UCn2 increases function of the failing heart. The simplicity of IV injection of a vector encoding a gene with beneficial paracrine effects to increase cardiac function is an attractive potential clinical strategy.

Pulmonary Oedema-Therapeutic Targets

Pulmonary oedema (PO) is a common manifestation of acute heart failure (AHF) and is associated with a high-acuity presentation and with poor in-hospital outcomes. The clinical picture of PO is dominated by signs of pulmonary congestion, and its pathogenesis has been attributed predominantly to an imbalance in Starling forces across the alveolar-capillary barrier. However, recent studies have demonstrated that PO formation and resolution is critically regulated by active endothelial and alveolar signalling. PO represents a medical emergency and treatment should be individually tailored to the urgency of the presentation and acute haemodynamic characteristics. Although, the majority of patients admitted with PO rapidly improve as result of conventional intravenous (IV) therapies, treatment of PO remains largely opinion based as there is a general lack of good evidence to guide therapy. Furthermore, none of these therapies showed simultaneous benefit for symptomatic relief, haemodynamic improvement, increased survival and end-organ protection. Future research is required to develop innovative pharmacotherapies capable of relieving congestion while simultaneously preventing end-organ damage.

Current and future G protein-coupled receptor signaling targets for heart failure therapy

Although there have been significant advances in the therapy of heart failure in recent decades, such as the introduction of β-blockers and antagonists of the renin–angiotensin–aldosterone system, this devastating disease still carries tremendous morbidity and mortality in the western world. G protein-coupled receptors, such as β-adrenergic and angiotensin II receptors, located in the membranes of all three major cardiac cell types, ie, myocytes, fibroblasts, and endothelial cells, play crucial roles in regulation of cardiac function in health and disease. Their importance is reflected by the fact that, collectively, they represent the direct targets of over one-third of the currently approved cardiovascular drugs used in clinical practice. Over the past few decades, advances in elucidation of the signaling pathways they elicit, specifically in the heart, have led to identification of an increasing number of new molecular targets for heart failure therapy. Here, we review these possible targets for heart failure therapy that have emerged from studies of cardiac G protein-coupled receptor signaling in health and disease, with a particular focus on the main cardiac G protein-coupled receptor types, ie, the β-adrenergic and the angiotensin II type 1 receptors. We also highlight key issues that need to be addressed to improve the chances of success of novel therapies directed against these targets.