Direct inotropic effects of exogenous and endogenous urotensin-II: divergent actions in failing and nonfailing human myocardium

Urotensin II Receptor Modulation with 1,3,4-Benzotriazepin-2-one Tetrapeptide Mimics

Urotensin II receptor (UT) modulators that differentiate the effects of the endogenous cyclic peptide ligands urotensin II (UII) and urotensin II-related peptide (URP) offer potential for dissecting their respective biological roles in disease etiology. Selective modulators of hUII and URP activities were obtained using 1,3,4-benzotriazepin-2-one mimics of a purported bioactive γ-turn conformation about the Bip-Lys-Tyr tripeptide sequence of urocontrin ([Bip4]URP). Considering an active β-turn conformer about the shared Phe-Trp-Lys-Tyr sequence of UII and URP, 8-substituted 1,3,4-benzotriazepin-2-ones were designed to mimic the Phe-Bip-Lys-Tyr tetrapeptide sequence of urocontrin, synthesized, and examined for biological activity. Subtle 5- and 8-position modifications resulted in biased signaling and selective modulation of hUII- or URP-induced vasoconstriction. For example, p-hydroxyphenethyl analogs 17b-d were strong Gα13 and βarr1 activators devoid of Gαq-mediated signaling. Tertiary amides 15d and 17d negatively modulated hUII-induced vasoconstriction without affecting URP-mediated responses. Benzotriazepinone carboxamides proved to be exceptional tools for elucidating the pharmacological complexity of UT.

Urantide Improves Cardiac Function, Modulates Systemic Cytokine Response, and Increases Survival in A Murine Model of Endotoxic Shock

INTRODUCTION

Urotensin II is a potent vasoactive peptide activating the the G protein-coupled urotensin II receptor UT, and is involved in systemic inflammation and cardiovascular functions. The aim of our work was to study the impact of the UT antagonist urantide on survival, systemic inflammation, and cardiac function during endotoxic shock.

METHODS

C57Bl/6 mice were intraperitoneally injected with lipopolysaccharide (LPS) and then randomized to be injected either by urantide or NaCl 0.9% 3, 6, and 9 h (H3, H6, H9) after LPS. The effect of urantide on the survival rate, the levels of cytokines in plasma at H6, H9, H12, the expression level of nuclear factor-kappa B (NF-κB-p65) in liver and kidney (at H12), and the cardiac function by trans-thoracic echocardiography from H0 to H9 was evaluated.

RESULTS

Urantide treatment improved survival (88.9% vs. 30% on day 6, P < 0.05). This was associated with changes in cytokine expression: a decrease in IL-6 (2,485 [2,280-2,751] pg/mL vs. 3,330 [3,119-3,680] pg/mL, P < 0.01) at H6, in IL-3 (1.0 [0.40-2.0] pg/mL vs. 5.8 [3.0-7.7] pg/mL, P < 0.01), and IL-1β (651 [491-1,135] pg/mL vs. 1,601 [906-3,010] pg/mL, P < 0.05) at H12 after LPS administration. Urantide decreased the proportion of cytosolic NF-κB-p65 in liver (1.3 [0.9-1.9] vs. 3.2 [2.3-4], P < 0.01) and kidney (0.3 [0.3-0.4] vs. 0.6 [0.5-1.1], P < 0.01). Urantide improved cardiac function (left ventricular fractional shortening: 24.8 [21.5-38.9] vs. 12.0 [8.7-17.6] %, P < 0.01 and cardiac output: 30.3 [25.9-39.8] vs. 15.1 [13.0-16.9] mL/min, P < 0.0001).

CONCLUSION

These results show a beneficial curative role of UT antagonism on cytokine response (especially IL-3), cardiac dysfunction, and survival during endotoxic shock in mice, highlighting a potential new therapeutic target for septic patients.

Novel insights into the role of urotensin II in cardiovascular disease

Urotensin II (UII) is a vasoactive peptide that interacts with a specific receptor called the UT receptor. UII has been implicated in cardiovascular regulation, with promising therapeutic applications based on UT receptor antagonism. The endogenous ligands of the UT receptor: UII and urotensin-related peptide (URP), differentially bind and activate this receptor. Also, the receptor localization is not restricted to the plasma membrane, possibly inducing different physiological responses that could support its inconsistent, but potent, vasoactive activity. These properties could explain the disappointing outcomes in clinical studies, in contrast to the positive preclinical results regarding heart failure, pulmonary hypertension, atherosclerosis and diabetes mellitus. These aspects should be considered in future investigations to a better comprehension of the role of UII as a potential therapeutic target.

Synthesis and SAR of 5-aryl-furan-2-carboxamide derivatives as potent urotensin-II receptor antagonists

The synthesis and biological evaluation as potential urotensin-II receptor antagonists of a series of 5-arylfuran-2-carboxamide derivatives 1, bearing a 4-(3-chloro-4-(piperidin-4-yloxy)benzyl)piperazin-1-yl group, are described. The results of a systematic SAR investigation of furan-2-carboxamides with C-5 aryl groups possessing a variety of aryl ring substituents led to identification of the 3,4-difluorophenyl analog 1y as a highly potent UT antagonist with an IC₅₀ value of 6 nM. In addition, this substance was found to display high metabolic stability, and low hERG inhibition and cytotoxicity, and to have an acceptable PK profile.

Engineering Cardiac Muscle Tissue: A Maturating Field of Research

Twenty years after the initial description of a tissue engineered construct, 3-dimensional human cardiac tissues of different kinds are now generated routinely in many laboratories. Advances in stem cell biology and engineering allow for the generation of constructs that come close to recapitulating the complex structure of heart muscle and might, therefore, be amenable to industrial (eg, drug screening) and clinical (eg, cardiac repair) applications. Whether the more physiological structure of 3-dimensional constructs provides a relevant advantage over standard 2-dimensional cell culture has yet to be shown in head-to-head-comparisons. The present article gives an overview on current strategies of cardiac tissue engineering with a focus on different hydrogel methods and discusses perspectives and challenges for necessary steps toward the real-life application of cardiac tissue engineering for disease modeling, drug development, and cardiac repair.

A novel urotensin II receptor antagonist, KR-36996, improved cardiac function and attenuated cardiac hypertrophy in experimental heart failure

Urotensin II and its receptor are thought to be involved in various cardiovascular diseases such as heart failure, pulmonary hypertension and atherosclerosis. Since the regulation of the urotensin II/urotensin II receptor offers a great potential for therapeutic strategies related to the treatment of cardiovascular diseases, the study of selective and potent antagonists for urotensin II receptor is more fascinating. This study was designed to determine the potential therapeutic effects of a newly developed novel urotensin II receptor antagonist, N-(1-(3-bromo-4-(piperidin-4-yloxy)benzyl)piperidin-4-yl)benzo[b]thiophene-3-carboxamide (KR-36996), in experimental models of heart failure. KR-36996 displayed a high binding affinity (Ki=4.44±0.67nM) and selectivity for urotensin II receptor. In cell-based study, KR-36996 significantly inhibited urotensin II-induced stress fiber formation and cellular hypertrophy in H9c2_UT cells. In transverse aortic constriction-induced cardiac hypertrophy model in mice, the daily oral administration of KR-36996 (30mg/kg) for 14 days significantly decreased left ventricular weight by 40% (P<0.05). In myocardial infarction-induced chronic heart failure model in rats, repeated echocardiography and hemodynamic measurements demonstrated remarkable improvement of the cardiac performance by KR-36996 treatment (25 and 50mg/kg/day, p.o.) for 12 weeks. Moreover, KR-36996 decreased interstitial fibrosis and cardiomyocyte hypertrophy in the infarct border zone. These results suggest that potent and selective urotensin II receptor antagonist could efficiently attenuate both cardiac hypertrophy and dysfunction in experimental heart failure. KR-36996 may be useful as an effective urotensin II receptor antagonist for pharmaceutical or clinical applications.

The value of urotensin II in patients with left-sided rheumatic valvular regurgitation

Aims

Rheumatic valve diseases are most common etiological valve diseases in developing countries. Urotensin II is cardiovascular autacoid/hormone and may be associated with patients of heart valve diseases. The present study was to measure plasma urotensin II concentrations in patients with left-sided rheumatic valve diseases such as mitral regurgitation (MR) and aortic regurgitation (AR), and to examine its correlation with severity of valve impairment, function (New York Heart association, NYHA) class and pulmonary artery pressure (PAP).

Methods and results

Sixty patients with moderate to severe rheumatic left-sided valve regurgitation and 20 healthy controls were selected after performing the echocardiography. Plasma urotensin II level was measured in all subjects. The patients with MR and AR were significantly increased of left ventricular end diastolic dimension (LVEDD), left ventricular end systolic dimension (LVESD), left atrial diameter, PAP, but decreased of EF% versus the controls. Urotensin II level was highly significant in patients with MR (1.83 ± 0.92 ng/ml, P < 0.001) and AR (0.79 ± 0.3 ng/ml, P < 0.05) versus the controls (0.48 ± 0.13 ng/ml). Also, there was significant correlation between Urotensin II level and LVEDD (MR, r = 0.318, P = 0.03; AR, r = 0.805, P < 0.001), LVESD (MR, r = −0.271, P = 0.115; AR, r = 0.614, P = 0.001), and PAP (MR, r = 0.706, P < 0.001; AR, r = 0.129, P = 0.538).

Conclusion

Urotensin II was elevated in patients with rheumatic left-sided valvular regurgitation, and positively correlated with increased LVEDD (in both MR and AR), LVESD (only AR) and pulmonary artery pressure (only MR). Therefore, urotensin II level may be used as diagnostic biomarker in patients with rheumatic valvular diseases for assessment of the severity in parallel with echocardiography.

A Myocardial Slice Culture Model Reveals Alpha-1A-Adrenergic Receptor Signaling in the Human Heart

The authors used 52 nonfailing and failing human hearts to develop a simple, high throughput left ventricular myocardial slice model that is stable by ATP and viability assays for at least 3 days. The model supports studies of signaling, contraction, and viral transduction. They use the model to show for the first time that the alpha-1A-adrenergic receptor, which is present at very low abundance in the human myocardium, activates cardioprotective ERK with nanomolar EC50 in failing heart slices and stimulates a positive inotropic effect. This model should be useful for translational studies, to test whether molecules discovered in basic experiments are functional in the human heart.

•

Model for translational studies

•

Human LV slices

•

Simple, high throughput, viable

•

Assays signaling and contraction

•

Supports viral transduction

•

Useful for proof-of-concept in man

•

Shows the α1A-AR functions in human heart

Molecular evolution of GPCRs: Somatostatin/urotensin II receptors

Somatostatin (SS) and urotensin II (UII) are members of two families of structurally related neuropeptides present in all vertebrates. They exert a large array of biological activities that are mediated by two families of G-protein-coupled receptors called SSTR and UTS2R respectively. It is proposed that the two families of peptides as well as those of their receptors probably derive from a single ancestral ligand-receptor pair. This pair had already been duplicated before the emergence of vertebrates to generate one SS peptide with two receptors and one UII peptide with one receptor. Thereafter, each family expanded in the three whole-genome duplications (1R, 2R, and 3R) that occurred during the evolution of vertebrates, whereupon some local duplications and gene losses occurred. Following the 2R event, the vertebrate ancestor is deduced to have possessed three SS (SS1, SS2, and SS5) and six SSTR (SSTR1-6) genes, on the one hand, and four UII (UII, URP, URP1, and URP2) and five UTS2R (UTS2R1-5) genes, on the other hand. In the teleost lineage, all these have been preserved with the exception of SSTR4. Moreover, several additional genes have been gained through the 3R event, such as SS4 and a second copy of the UII, SSTR2, SSTR3, and SSTR5 genes, and through local duplications, such as SS3. In mammals, all the genes of the SSTR family have been preserved, with the exception of SSTR6. In contrast, for the other families, extensive gene losses occurred, as only the SS1, SS2, UII, and URP genes and one UTS2R gene are still present.

Circulating levels of the vasoactive peptide urotensin II in patients with acute coronary syndrome and stable coronary artery disease

Urotensin II (UII) is a vasoactive peptide with various roles in cardiovascular physiology and pathophysiology. There is an accumulating evidence implicating UII in atherosclerosis and coronary artery disease, making it an important target in acute coronary syndrome (ACS). In this study, we sought to determine the plasma levels of UII in ACS patients within 48 h of clinical presentation and after a 12-week recovery period. We compared them to patients with stable coronary artery disease (CAD) and a control group of normolipidemic subjects without known CAD. Using a highly sensitive ELISA technique, we measured plasma UII in 27 ACS patients, 26 stable CAD patients and 22 age-matched controls. ACS patients had significantly elevated plasma UII during the first 48 h of clinical presentation compared to stable CAD patients and controls. We also found significant positive correlations between UII and CRP and with triglycerides and a significant negative correlation between UII and EF. There was no correlation with LDL-C. In conclusion, plasma UII levels were elevated in patients with acute coronary syndrome, particularly immediately after clinical presentation. This suggests an upregulation of UII expression in ACS.

Differential expression of PDE5 in failing and nonfailing human myocardium

BACKGROUND

Recognizing that inhibitors of phosphodiesterase type 5 (PDE5) are increasingly employed in patients with pulmonary hypertension and right ventricular (RV) failure, we examined PDE5 expression in the human RV and its impact on myocardial contractility.

METHODS AND RESULTS

Tissue extracts from the RV of 20 patients were assayed for PDE5 expression using immunoblot and immunohistochemical staining. Tissues were selected from groups of nonfailing organ donors and transplant recipients with endstage ischemic cardiomyopathy or idiopathic dilated cardiomyopathy. Among dilated cardiomyopathy patients, subgroups with mild or severe RV dysfunction and prior left ventricular assist devices were analyzed separately. Our results showed that PDE5 abundance increased more than 4-fold in the RVs of the ischemic cardiomyopathy compared with the nonfailing group. In dilated cardiomyopathy, PDE5 upregulation was more moderate and varied with the severity of RV dysfunction. Immunohistochemical staining confirmed that cardiac myocytes contributed to the upregulation in the failing hearts. In functional studies, PDE5 inhibition produced little change in developed force in RV trabeculae from nonfailing hearts but produced a moderate increase in RV trabeculae from failing hearts.

CONCLUSIONS

Our results showed the etiology- and severity-dependent upregulation of myocyte PDE5 expression in the RV and the impact of this upregulation on myocardial contractility. These findings suggest that RV PDE5 expression could contribute to the pathogenesis of RV failure, and direct myocardial responses to PDE5 inhibition may modulate the indirect responses mediated by RV afterload reduction.

GSK1562590, a slowly dissociating urotensin-II receptor antagonist, exhibits prolonged pharmacodynamic activity ex vivo

BACKGROUND AND PURPOSE

Recently identified antagonists of the urotensin-II (U-II) receptor (UT) are of limited utility for investigating the (patho)physiological role of U-II due to poor potency and limited selectivity and/or intrinsic activity.

EXPERIMENTAL APPROACH

The pharmacological properties of two novel UT antagonists, GSK1440115 and GSK1562590, were compared using multiple bioassays.

KEY RESULTS

GSK1440115 (pK(i)= 7.34-8.64 across species) and GSK1562590 (pK(i)= 9.14-9.66 across species) are high affinity ligands of mammalian recombinant (mouse, rat, cat, monkey, human) and native (SJRH30 cells) UT. Both compounds exhibited >100-fold selectivity for UT versus 87 distinct mammalian GPCR, enzyme, ion channel and neurotransmitter uptake targets. GSK1440115 showed competitive antagonism at UT in arteries from all species tested (pA(2)= 5.59-7.71). In contrast, GSK1562590 was an insurmountable UT antagonist in rat, cat and hUT transgenic mouse arteries (pK(b)= 8.93-10.12 across species), but a competitive antagonist in monkey arteries (pK(b)= 8.87-8.93). Likewise, GSK1562590 inhibited the hU-II-induced systemic pressor response in anaesthetized cats at a dose 10-fold lower than that of GSK1440115. The antagonistic effects of GSK1440115, but not GSK1562590, could be reversed by washout in rat isolated aorta. In ex vivo studies, GSK1562590 inhibited hU-II-induced contraction of rat aorta for at least 24 h following dosing. Dissociation of GSK1562590 binding was considerably slower at rat than monkey UT.

CONCLUSIONS AND IMPLICATIONS

Whereas both GSK1440115 and GSK1562590 represent high-affinity/selective UT antagonists suitable for assessing the (patho)physiological role of U-II, only GSK1562590 exhibited sustained UT residence time and improved preclinical efficacy in vivo.