Urocortins in heart failure

Beyond appetite regulation: Targeting energy expenditure, fat oxidation, and lean mass preservation for sustainable weight loss

New appetite-regulating antiobesity treatments such as semaglutide and agents under investigation such as tirzepatide show promise in achieving weight loss of 15% or more. Energy expenditure, fat oxidation, and lean mass preservation are important determinants of weight loss and weight-loss maintenance beyond appetite regulation. This review discusses prior failures in clinical development of weight-loss drugs targeting energy expenditure and explores novel strategies for targeting energy expenditure: mitochondrial proton leak, uncoupling, dynamics, and biogenesis; futile calcium and substrate cycling; leptin for weight maintenance; increased sympathetic nervous system activity; and browning of white fat. Relevant targets for preserving lean mass are also reviewed: growth hormone, activin type II receptor inhibition, and urocortin 2 and 3. We endorse moderate modulation of energy expenditure and preservation of lean mass in combination with efficient appetite reduction as a means of obtaining a significant, safe, and long-lasting weight loss. Furthermore, we suggest that the regulatory guidelines should be revisited to focus more on the quality of weight loss and its maintenance rather than the absolute weight loss. Commitment to this research focus both from a scientific and from a regulatory point of view could signal the beginning of the next era in obesity therapies.

Progress in understanding the roles of Urocortin3 (UCN3) in the control of appetite from studies using animal models

Urocortin3 (UCN3), the newest member of corticotrophin releasing hormone (CRH) family polypeptides, is an anorexic factor discovered in 2001, which has a strong inhibitory effect on animal appetite regulation. UCN3 is widely distributed in various tissues of animals and has many biological functions. Based on the research progress of UCN3 on mammals and non-mammals, this paper summarized the discovery, tissue distribution, appetite regulation and mechanism of UCN3 in animals, in order to provide a reference for feeding regulation and growth in mammals and fish in further research and production.

Urocortinergic system in the epididymis of the normal and cryptorchid dogs

Cryptorchidism is associated with changes in the gonads and the spermatic duct system, which may cause infertility problems. Urocortin (UCN) is a corticotrophin-releasing hormone (CRH)-related peptide, which affects several functions of male genital organs. The aim of the present study was to investigate the expression of UCN and its receptors CRHR1 and CRHR2 using immunohistochemistry, western blotting and real-time reverse transcription polymerase chain reaction in tissues collected from the epididymis of normal and cryptorchid dogs. The lumen of the cryptic epididymal duct was found to be relatively smaller than that of the normal one, and interstitial tissue was abundant in the cryptic epididymis. In addition, only a few spermatids were observed in the lumen of the epididymal duct. Results showed that UCN, CRHR2 and CRHR1 were expressed in tissues collected from normal and cryptic epididymal ducts. Urocortin- and CRHR2-immunoreactivities (IRs) were detected in the principal cells of the caput, corpus and cauda of the normal and cryptic epididymides. CRHR1-IR was detected in vascular smooth muscles and fibromuscular cells surrounding epididymal tubules of the normal and cryptorchid dogs. Expression levels of UCN and CRHR2 mRNA were higher in cryptic epididymal ducts than that in normal epididymal ducts. These results suggest that UCN and its receptors might play a role in regulating the maturation and storage of spermatozoa. These findings indicated that the expression of these proteins could be modulated by the cryptorchidism condition.

Corticotropin-Releasing Hormone Family and Their Receptors in the Cardiovascular System

The identification of corticotropin-releasing hormone (CRH) has led to the discovery of a growing family of ligands and receptors. CRH receptor 1 (CRHR1) and CRHR2 are mammalian G-protein coupled receptors (GPCRs) with high affinity for CRH and the CRH family of peptides. CRHR1 is predominantly expressed in the brain and plays a vital role in the hypothalamic-pituitary-adrenal (HPA) axis stress responses by secreting adrenal corticotropic hormone (ACTH). CRHR2 is predominantly expressed in the heart, and a CRHR2-specific ligand, urocortin 2 (UCN2), shows positive cardiac chronotropic and inotropic effects through 3´,5´-cyclic adenosine monophosphate (cAMP) signaling in response to CRHR2-mediated Gαs activation in mice and humans. Central administration of the CRH family of peptides increases mean arterial pressure through CRHR1 activation, whereas peripheral administration of the peptides decreases mean arterial pressure through CRHR2 activation. These observations have led to further investigations of CRHR2 as an important and unique GPCR in the physiological and pathological functioning of the cardiovascular (CV) system. Moreover, recent clinical trials demonstrate CRHR2 as a potentially therapeutic target in the treatment of heart failure. We present recent reviews of the role of CRHRs in basic CV physiology and in the pathophysiology of CV diseases.

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.

High-Sensitivity Sandwich ELISA for Plasma NT-proUcn2: Plasma Concentrations and Relationship to Mortality in Heart Failure

BACKGROUND

Urocortin 2 (Ucn2) has powerful hemodynamic, renal, and neurohormonal actions and likely participates in normal circulatory homeostasis and the compensatory response to heart failure (HF). A validated assay for endogenous circulating Ucn2 would facilitate investigations into Ucn2 physiology and elucidate its derangement and potential as a biomarker in heart disease.

METHOD

We developed a chemiluminescence-based sandwich ELISA to measure plasma N-terminal (NT)-proUcn2 in non-HF patients (control; n = 160) and HF patients with reduced (HFREF; n = 134) and preserved (HFPEF; n = 121) left ventricular ejection fraction (LVEF).

RESULTS

The ELISA had a limit of detection of 8.47 ng/L (1.52 pmol/L) and working range of 23.8–572 ng/L. Intra- and interassay CV and total error were 4.8, 16.2, and 17.7%, respectively. The median (interquartile range) plasma NT-proUcn2 concentration in controls was 112 (86–132) ng/L. HFREF, HFPEF, and all HF plasma concentrations were significantly increased [117 (98–141) ng/L, P = 0.0007; 119 (93–136) ng/L, P = 0.0376, and 119 (97–140) ng/L, P = 0.001] compared with controls but did not differ significantly between HFREF and HFPEF. NT-proUcn2 was modestly related to age (r = 0.264, P = 0.001) and cardiac troponin T (r = 0.258, P = 0.001) but not N-terminal pro-B-type natriuretic peptide, body mass index, LVEF, or estimated glomerular filtration rate. On multivariate analysis, plasma NT-proUcn2 was independently and inversely related to 2-year mortality in HF.

CONCLUSIONS

The validated ELISA measured human NT-proUcn2 in plasma and showed modest but significant increases in HF patients compared with controls. In HF, the unusual inverse relationship between plasma NT-proUcn2 and 2-year mortality portends potential prognostic value but requires further corroboration.

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.

Corticotropin-releasing factor (CRF) system localization in human fetal heart

OBJECTIVE

The corticotropin-releasing factor (CRF) family consists of the neuropeptides CRF, Ucn I, II and III and the binding sites CRFR1, CRFR2 and CRF-BP. It regulates stress response and the homeostasis of an organism. In this study, we examined the presence of the CRF system in the human hearts of normal and pathological fetuses.

DESIGN

Heart tissues from 40 archival human fetuses were divided into Group A (without pathology, 'normal'), Group B (with chromosomal abnormalities) and Group C (with congenital disorders). Immunohistochemistry was used to localize the CRF system. Results correlated to gestational trimester and pathology.

RESULTS

Immunoreactivity for all antigens was found in cardiac myocytes of all groups, in almost all samples, except Ucn III which was present in almost half of the fetuses of Groups B and C and was not detected at all in Group A. Ucn III was more often present during the earlier stage of development (<21 weeks) and in fetuses with congenital disorders. In a fetus diagnosed with heart pathology, all but Ucn III antigens were also present.

CONCLUSIONS

We localized a complete CRF system in the human fetal heart and correlated the presence of Ucn III to development and pathology. More studies are needed to verify and clarify the exact role of the CRF system in the human fetal heart.

Urocortin 2 in cardiovascular health and disease

Urocortin (Ucn)-2 - corticotropin-releasing hormone receptor 2 signaling has favorable effects in the cardiovascular system, including coronary vasodilatation, with increased coronary blood flow and conductance and augmented cardiac contractility and output, as well as protection against ischemia/reperfusion injury. Indeed, several animal studies have confirmed the salutary therapeutic effects of Ucn-2 in chronic heart failure, with improvements in cardiac performance and animal survival. In addition, recent clinical trials have demonstrated the benefits of Ucn-2 in patients with stable chronic heart failure on optimal medical therapy.

A His6-SUMO-eXact tag for producing human prepro-urocortin 2 in Escherichia coli for raising monoclonal antibodies

This is a first report of recombinant production of human prepro-Urocortin 2 in Escherichia coli by N-terminal fusion with a triple His₆-SUMO-eXact tag and its subsequent use as an antigen for the production and screening of very high affinity monoclonal antibodies. The rationale for this combinatorial construct is that the His tag allows first step protein purification of insoluble and soluble proteins, the SUMO tag enhances protein expression level and solubility, while the eXact tag facilitates anion-triggered on-column cleavage of the triple tag to recover pure native proteins in a simple two-step protein purification procedure. Compared with an eXact fusion alone, the presence of the SUMO moiety enhanced overall expression levels by 4 to 10 fold but not the solubility of the highly basic prepro-Urocortin 2. Insoluble SUMO-eXact-preproUCN2 was purified in milligram quantities by denaturing IMAC and solubilized in native phosphate buffer by on-column refolding or step-wise dialysis. Only a small fraction of this solubilized protein was able to bind onto the eXact™ affinity column and cleaved by NaF treatment. To test whether binding and cleavage failure was due to improperly refolded SUMO-eXact-preproUCN2 or to the presence of N- and C-terminal sequences flanking the eXact moiety, we created a SUMO-eXact-thioredoxin construct which was overexpressed mainly in the soluble form. This protein bound to and was cleaved efficiently on the eXact™ column to yield native thioredoxin. Solubilized SUMO-eXact-preproUCN2 was used successfully to generate two high affinity mouse monoclonal antibodies (KD~10⁻¹⁰ and 10⁻¹¹ M) specific to the pro-region of Urocortin 2.

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

AIMS

Human stresscopin is a corticotropin-releasing factor (CRF) type 2 receptor (CRFR2) selective agonist and a member of the CRF peptide family. Stimulation of CRFR2 improves cardiac output and left ventricular ejection fraction (LVEF) in patients with stable heart failure (HF) with reduced LVEF. We examined the safety, pharmacokinetics, and effects on haemodynamics and serum biomarkers of intravenous human stresscopin acetate (JNJ-39588146) in patients with stable HF with LVEF ≤ 35% and cardiac index (CI) ≤ 2.5 L/min/m(2).

METHODS AND RESULTS

Sixty-two patients with HF and LVEF ≤ 35% were instrumented with a pulmonary artery catheter and randomly assigned (ratio 3:1) to receive an intravenous infusion of JNJ-39588146 or placebo. The main study was an ascending dose study of three doses (5, 15, and 30 ng/kg/min) of study drug or placebo administered in sequential 1 h intervals (3 h total). Statistically significant increases in CI and reduction in systemic vascular resistance (SVR) were observed with both the 15 ng/kg/min (2 h time point) and 30 ng/kg/min (3 h time point) doses of JNJ-39588146 without significant changes in heart rate (HR) or systolic blood pressure (SBP). No statistically significant reductions in pulmonary capillary wedge pressure (PCWP) were seen with any dose tested in the primary analysis, although a trend towards reduction was seen.

CONCLUSION

In HF patients with reduced LVEF and CI, ascending doses of JNJ-39588146 were associated with progressive increases in CI and reductions in SVR without significant effects on PCWP, HR, or SBP.

TRIAL REGISTRATION

NCT01120210.

Vascular effects of urocortins 2 and 3 in healthy volunteers

BACKGROUND

Urocortin 2 and urocortin 3 are endogenous peptides with an emerging role in cardiovascular pathophysiology. We assessed their pharmacodynamic profile and examined the role of the endothelium in mediating their vasomotor effects in vivo in man.

METHODS AND RESULTS

Eighteen healthy male volunteers (23±4 years) were recruited into a series of double-blind, randomized crossover studies using bilateral forearm venous occlusion plethysmography during intra-arterial urocortin 2 (3.6 to 120 pmol/min), urocortin 3 (1.2 to 36 nmol/min), and substance P (2 to 8 pmol/min) in the presence or absence of inhibitors of cyclooxygenase (aspirin), cytochrome P450 metabolites of arachidonic acid (fluconazole), and nitric oxide synthase (L-NMMA). Urocortins 2 and 3 evoked arterial vasodilatation (P<0.0001) without tachyphylaxis but with a slow onset and offset of action. Inhibition of nitric oxide synthase with L-NMMA reduced vasodilatation to substance P and urocortin 2 (P≤0.001 for both) but had little effect on urocortin 3 (P>0.05). Neither aspirin nor fluconazole affected vasodilatation induced by any of the infusions (P>0.05 for all). In the presence of all 3 inhibitors, urocortin 2- and urocortin 3-induced vasodilatation was attenuated (P<0.001 for all) to a greater extent than with L-NMMA alone (P≤0.005).

CONCLUSIONS

Urocortins 2 and 3 cause potent and prolonged arterial vasodilatation without tachyphylaxis. These vasomotor responses are at least partly mediated by endothelial nitric oxide and cytochrome P450 metabolites of arachidonic acid. The role of urocortins 2 and 3 remains to be explored in the setting of human heart failure, but they have the potential to have major therapeutic benefits.

CLINICAL TRIAL REGISTRATION

http://www.clinicaltrials.gov//. Unique identifier: NCT01096706 and NCT01296607.

First survey and functional annotation of prohormone and convertase genes in the pig

Background

The pig is a biomedical model to study human and livestock traits. Many of these traits are controlled by neuropeptides that result from the cleavage of prohormones by prohormone convertases. Only 45 prohormones have been confirmed in the pig. Sequence homology can be ineffective to annotate prohormone genes in sequenced species like the pig due to the multifactorial nature of the prohormone processing. The goal of this study is to undertake the first complete survey of prohormone and prohormone convertases genes in the pig genome. These genes were functionally annotated based on 35 gene expression microarray experiments. The cleavage sites of prohormone sequences into potentially active neuropeptides were predicted.

Results

We identified 95 unique prohormone genes, 2 alternative calcitonin-related sequences, 8 prohormone convertases and 1 cleavage facilitator in the pig genome 10.2 assembly and trace archives. Of these, 11 pig prohormone genes have not been reported in the UniProt, UniGene or Gene databases. These genes are intermedin, cortistatin, insulin-like 5, orexigenic neuropeptide QRFP, prokineticin 2, prolactin-releasing peptide, parathyroid hormone 2, urocortin, urocortin 2, urocortin 3, and urotensin 2-related peptide. In addition, a novel neuropeptide S was identified in the pig genome correcting the previously reported pig sequence that is identical to the rabbit sequence. Most differentially expressed prohormone genes were under-expressed in pigs experiencing immune challenge relative to the un-challenged controls, in non-pregnant relative to pregnant sows, in old relative to young embryos, and in non-neural relative to neural tissues. The cleavage prediction based on human sequences had the best performance with a correct classification rate of cleaved and non-cleaved sites of 92% suggesting that the processing of prohormones in pigs is similar to humans. The cleavage prediction models did not find conclusive evidence supporting the production of the bioactive neuropeptides urocortin 2, urocortin 3, torsin family 2 member A, tachykinin 4, islet amyloid polypeptide, and calcitonin receptor-stimulating peptide 2 in the pig.

Conclusions

The present genomic and functional characterization supports the use of the pig as an effective animal model to gain a deeper understanding of prohormones, prohormone convertases and neuropeptides in biomedical and agricultural research.

Relevance of urocortins to cardiovascular disease

Acquired cardiovascular diseases such as coronary heart disease, peripheral artery disease and related vascular problems contribute to more than one-third of worldwide morbidity and mortality. In many instances, particularly in the under developed world, cardiovascular diseases are diagnosed at a late stage limiting the scope for improving outcomes. A range of therapies already exist for established cardiovascular disease, although there is significant interest in further understanding disease pathogenesis in order to improve diagnosis and achieve primary and secondary therapeutic goals. The urocortins are a group of recently defined peptide members of the corticotrophin-releasing factor family. Previous pre-clinical work and human association studies suggest that urocortins have potential to exert some beneficial and other detrimental effects on the heart and major blood vessels. More current evidence however favours beneficial effects of urocortins, for example these peptides have been shown to inhibit production of reactive oxygen species and vascular cell apoptosis, and thus may have potential to antagonise the progression of cardiovascular disease. This review summarises published data on the potential role of urocortins in cardiovascular disease.

Urocortin-2 induces vasorelaxation of coronary arteries isolated from patients with heart failure

1. Urocortin-2 (Ucn2) is a vasoactive peptide belonging to the corticotrophin-releasing factor (CRF) family that has potent cardiovascular actions. It has been suggested that Ucn2 participates in the pathophysiology of heart failure. However, little is known about the mechanisms underlying the action of Ucn2 in human coronary arteries. The aim of the present study was to assess the effects of Ucn2 on the vascular tone of human coronary arteries dissected from heart failure patients. 2. Human coronary arteries were dissected from the hearts of patients subjected to orthotopic heart transplantation. Coronary arteries were obtained from 17 patients with heart failure due to dilated cardiomyopathy of ischaemic origin in Stage III-IV of the New York Heart Association classification. Changes in tone were measured in arterial rings using force transducers. 3. Application of increasing concentrations of Ucn2 (5-20 nmol/L) to arterial rings precontracted with agonists induced dose-dependent relaxation of the coronary artery, which was independent of endothelial cell activation. Furthermore, the inhibition of the adenylyl cyclase by MDL-12 (100 nmol/L) and protein kinase A (PKA) by H89 (1 μmol/L) prevented Ucn2-mediated relaxation of coronary artery rings. 4. The results of the present study suggest that, in heart failure patients, Ucn2 could be useful in modulating coronary artery circulation independent of endothelial integrity through mechanisms that involve adenylyl cyclase activation and PKA stimulation. The findings warrant further investigation of the role of Ucn2 in circulatory regulation and its potential therapeutic application in heart disease.

Microinjections of urocortin1 into the nucleus ambiguus of the rat elicit bradycardia

Urocortins are members of the hypothalamic corticotropin-releasing factor (CRF) peptide family. Urocortin1 (UCN1) mRNA has been reported to be expressed in the brainstem neurons. The present investigation was carried out to test the hypothesis that microinjections of UCN1 into the nucleus ambiguus (nAmb) may elicit cardiac effects. Urethane-anesthetized, artificially ventilated, adult male Wistar rats, weighing between 300-350 g, were used. nAmb was identified by microinjections of l-glutamate (5 mM, 30 nl). Microinjections (30 nl) of different concentrations (0.062, 0.125, 0.25, and 0.5 mM) of UCN1 into the nAmb elicited bradycardic responses (26.5 ± 1, 30.1 ± 1.7, 46.9 ± 1.7, and 40.3 ± 2.6 beats/min, respectively). These heart rate responses were not accompanied by significant changes in mean arterial pressure. The bradycardic responses to maximally effective concentration of UCN1 (0.25 mM) were significantly (P < 0.05) attenuated by prior microinjections of a selective antagonist (NBI 27914, 1.5 mM) for CRF type 1 receptor (CRF1R). Prior microinjections of ionotropic glutamate receptor (iGLUR) antagonists [d-(-)-2-amino-7-phosphono-heptanoic acid and 2,3-dioxo-6-nitro-1,2,3,4-tetrahydrobenzo-(f)quinoxaline-7-sulfonamide disodium] also attenuated the bradycardia elicited by UCN1 microinjections into the nAmb. Microinjections of NBI 27914 (1.5 mM) into the nAmb did not alter baroreflex responses. Bilateral vagotomy abolished the bradycardic responses to microinjections of UCN1 into the nAmb. These results indicated that 1) microinjections of UCN1 into the nAmb elicited bradycardia, 2) the bradycardia was vagally mediated, 3) activation of CRF1Rs in the nAmb was responsible for the actions of UCN1, and 4) activation of iGLURs in the nAmb also participated in the bradycardia elicited by UCN1.