INTRODUCTION Ascites is a frequent complication to cirrhosis. When ascites becomes refractory to standard diuretic pharmacotherapy, patients are facing a median survival of less than one year and most likely a need for frequent hospitalisations due to large-volume paracentesis or complications. An unmet need exists for new and improved treatments of refractory ascites and the present study investigates the potential of the natriuretic peptide ularitide for this indication. METHODS We aim to investigate the effects, safety and tolerability of ularitide as treatment of refractory ascites in cirrhosis patients in a randomised, double-blind, placebo-controlled trial. Participants receive ularitide or placebo as a continuous intravenous infusion during hospitalisation as an add-on to any diuretic treatment. Clinical end points include increase in diuresis and natriuresis, reduction in body weight and waist circumference, safety end points, as well as changes in plasma concentrations of renal and systemic response biomarkers and hormones. CONCLUSION This study will provide evidence concerning the potential of ularitide in treating cirrhosis patients with refractory ascites. FUNDING This investigator-initiated trial is supported by ADS AIPHIA Development Services AG. TRIAL REGISTRATION Clinicaltrials.gov (NCT04311489) and EU Drug Regulating Authorities Clinical Trials (EudraCT: 2019-002268-28). The trial will be conducted in accordance with good clinical practice, the Declaration of Helsinki and applicable demands from Danish authorities.

Treatment for acutely decompensated heart failure (ADHF) has not changed much in the last two decades. Currently available therapies have variable efficacy and can be associated with adverse outcomes. Natriuretic peptides properties include diuresis, natriuresis, vasorelaxation, inhibition of renin-angiotensin-aldosterone system, and are thus chosen in the treatment of ADHF. Two forms of natriuretic peptides are currently available for the treatment of ADHF. Urodilatin (INN: ularitide) represents another member of the natriuretic peptide family with a unique molecular structure that may provide distinct benefits in the treatment of ADHF. Early clinical exploratory and Phase II studies have demonstrated that ularitide has potential cardiovascular and renal benefits. Ularitide is currently being tested in the Phase III TRUE-AHF clinical study. TRUE-AHF has features that may be different when compared with other recent outcome studies in ADHF. These distinct differences aim to maximize clinical effects and minimize potential adverse events of ularitide. However, whether this rationale translates into a better outcome needs to be awaited.

Since its discovery glucagon-like peptide-1 (GLP-1) is investigated as a treatment for type II diabetes based on its major function as insulin secretagogue. A therapeutic use is, however, limited by its short biological half-life in the range of minutes, predominantly caused via degradation catalyzed by dipeptidyl peptidase IV (DPP-IV). Therefore, we aimed to design a GLP-1 analogue exhibiting resistance against DPP-IV-catalyzed inactivation while retaining its biological activity. By means of matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) we have studied the stability of the N-terminally blocked new analogue Ac-GLP-1-(7-34)-amide against DPP-IV and compared it with both unblocked GLP-1-(7-34)-amide and the major naturally occurring form GLP-1-(7-36)-amide. GLP-1-(7-36)-amide and the C-terminally two amino acid residues shorter GLP-1-(7-34)-amide rapidly generated peptide fragments truncated by the N-terminal dipeptide. In contrast, the N-terminal blocked Ac-GLP-1-(7-34)-amide was not degraded in the presence of DPP-IV over a period of at least two hours. Ac-GLP-1-(7-34)-amide induced a concentration-dependent increase of intracellular cAMP production and insulin release from rat insulinoma RIN-m5F cells to an extent comparable to that found for the N-terminally unblocked peptides GLP-1-(7-34)-amide and GLP-1-(7-36)-amide. Ac-GLP-1-(7-34)-amide may thus have the potential to act as a new long-acting GLP-1 analogue with significant resistance against DPP-IV and retained biological activity in vitro. Further research is required to investigate whether Ac-GLP-1-(7-34)-amide also exhibits its characteristics in animal models and humans.

Background Renal function frequently deteriorates in decompensated heart failure (DHF) patients, and one determinant is reduced renal blood flow. This may, in part, result from low cardiac output (CO), reduced mean arterial pressure (MAP), and venous congestion. The combined impact of both venous congestion (elevated right atrial pressure [RAP]) and low MAP are reflected by a reduced pressure gradient MAP-RAP. This study investigated the renal effects of ularitide, a synthetic version of the renal natriuretic peptide urodilatin in DHF patients.Methods In SIRIUS II, a double-blind phase II trial, 221 patients hospitalized for DHF (with dyspnea at rest or minimal activity, cardiac index <= 2.5 L/min per square meter, and pulmonary artery wedge pressure >= 18 mm Hg) were randomized to a single 24-hour infusion of ularitide (7.5, 15, or 30 ng/kg per minute) or placebo added to standard therapy.Results Estimated glomerular filtration rate, serum creatinine, creatinine clearance, and blood urea nitrogen (BUN) were not impaired by ularitide throughout infusion and during a 2-day follow-up period. At 24 hours, 15 ng/kg per minute ularitide reduced BUN levels (-4.07 +/- 12.30 vs -0.20 +/- 7.50 for placebo, P < .05). Ularitide at 15 and 30 ng/kg per minute rapidly elevated CO with sustained effects, Although 15 ng/kg per minute ularitide preserved the pressure gradient MAP-RAP, 30 ng/kg per minute ularitide reduced MAP-RAP by -7.8 +/- 10.6 mm Hg vs -2.4 +/- 9.8 mm Hg for placebo (P < .01, at 6 hours). A strong inverse correlation between MAP-RAP and BUN levels (Corr = -0.50579, P = .00015) was observed with 15 ng/kg per minute ularitide.Conclusions Single 24-hour infusions of ularitide at 15 ng/kg per minute preserved short-term renal function in DHF patients possibly by both elevating CO and maintaining the MAP-RAP pressure gradient.

Peptide hormones belonging to the natriuretic peptide (NP) family play an important role in maintaining cardiac and renal function by regulating fluid volume, pressure, and sodium concentration. The principal members of this family are atrial natriuretic peptide (ANP); urodilatin (URO); brain natriuretic peptide (BNP); and C-type natriuretic peptide (CNP). The physiologic effects of these molecules generally lead to vasodilation, natriuresis, and diuresis, and regulate sodium and water homeostasis, rendering them promising candidates for potential therapeutic use in cardiovascular and renal dysfunction. This chapter reviews the biochemistry, physiology, and pharmacologic potential of the major natriuretic peptides, with particular emphasis on their clinical importance in the treatment of acute heart failure syndrome (AHFS).

Background: The renal natriuretic peptide Ularitide improves symptoms and hemodynamics in patients with decompensated heart failure (DHF). Here, we investigated the effects of Ularitide on myocardial oxygen consumption (MVO2), and on markers of both myocardial injury (troponin I, TnI and troponin T, TnT) and renal function (cystatin C). Methods: In this double-blinded trial, 221 DHF patients with dyspnea, cardiac index ≤ 2.5 L/min/m2, and pulmonary capillary wedge pressure ≥ 18 mmHg were randomized to receive a single 24-hour (h) infusion of Ularitide (7.5, 15, or 30 ng/kg/min) or placebo. Results: The time course of plasma cystatin C levels (table) through 72h revealed no differences between Ularitide groups compared to placebo. Mean levels of cystatin C were elevated at baseline and were unchanged at the end of dosing. Subsequently, they increased further at 48 and 72h in all groups including placebo. Ularitide improved cardiac pump function in contrast to placebo. Heart rate was unchanged and Ularitide tended to decrease MVO2. Levels of TnI and TnT were low or undetectable in the majority of subjects and there were no apparent increases following treatment with Ularitide or placebo. A few subjects had elevated levels of troponin at baseline and these remained relatively unchanged over time. No differences were observed in Ularitide-treated groups compared to placebo. Conclusions: Ularitide infused for 24h in DHF patients had no apparent deleterious effects on short-term renal function as measured by plasma cystatin C over 72h. In addition, there were no signals of ischemic myocardial damage as measured by TnI or TnT in the Ularitide groups compared to placebo through 72h.Tabled 1Plasma cystatin C levels (mean ± SD)Placebo7.5 ng/kg/min Ularitide15 ng/kg/min Ularitide30 ng/kg/min UlaritideBaseline1.28 ± 0.561.29 ± 0.501.19 ± 0.321.26 ± 0.5324h1.24 ± 0.521.34 ± 0.531.17 ± 0.341.28 ± 0.6048h1.43 ± 0.651.46 ± 0.591.26 ± 0.371.49 ± 0.7372h1.43 ± 0.691.42 ± 0.561.30 ± 0.431.51 ± 0.74 Open table in a new tab

BACKGROUND:Identification of markers for prediction of the clinical course of diabetic nephropathy remains a major challenge in disease management. We established a proteomics approach for identification of diabetic nephropathy-related biomarkers in urine.METHODS:We used SELDI-TOF mass spectrometry and SAX2 protein arrays to compare protein profiles from urine of 4 defined patient groups. Samples from patients with type 2 diabetes (DM; n = 45) without nephropathy and without microalbuminuria (DM-WNP), patients with DM with macro- or microalbuminuria (DM-NP; n = 38), patients with proteinuria due to nondiabetic renal disease (n = 34), and healthy controls (n = 45) were analyzed. Anionic exchange, reversed-phase fractionation, gel electrophoresis, and mass spectrometry were used to isolate and identify proteins with high discriminatory power.RESULTS:A protein with m/z 6188 (P <0.0000004) was strongly released in the urine of healthy controls, patients with proteinuria due to nondiabetic disease, and DM-WNP in contrast to DM-NP patients. An m/z 14 766 protein (P <0.00008) was selectively excreted in the urine of DM-NP patients, whereas the protein with m/z 11 774 (P <0.000004) was significantly excreted by patients with proteinuria and DM-NP. The m/z 11 774 and m/z 14 766 mass peaks were identified as beta(2)-microglobulin and UbA52, a ubiquitin ribosomal fusion protein, respectively. The protein with m/z 6188 was identified as a processed form of ubiquitin.CONCLUSION:The release of high amounts of UbA52 in urine of DM-NP patients could serve as a diagnostic marker, whereas the lack of the short form of ubiquitin raises interesting questions about the pathophysiology.

Urodilatin, a natriuretic peptide with four additional amino acids compared to atrial natriuretic peptide (ANP), is generated in distal tubule cells of the renal nephron. Whereas the fundamental role of ANP in the kidney, namely the regulation of natriuresis and diuresis, is questionable, urodilatin may be responsible for this task when secreted into the lumen of the distal tubule. More stable than ANP, it can act as a paracrine regulator and bind to its specific receptors located in the luminal membrane of cortical collecting duct (CCD) and inner medullary collecting duct (IMCD), thus, displaying its effects on cellular pH, Na+ transport, and H2O homeostasis. Urodilatin might also play a future role in the treatment of acute decompensated heart failure, acute renal failure, and bronchial asthma.

Aims Ularitide is a synthetic form of urodilatin, a natriuretic peptide produced in the kidney with vasodilating, natriuretic, and diuretic effects, that offers promise for the management of decompensated heart failure (DHF). We assessed the efficacy and safety of ularitide in treating patients with DHF. Methods and results In this Phase II randomized, double-blind, placebo-controlled trial, 221 DHF patients received either placebo (n=53) or ularitide at 7.5 ng/kg/min (n=60), 15 ng/kg/min (n=53), or 30 ng/kg/min (n=55) as a 24-h continuous infusion. At 6 h, ularitide demonstrated a significant decrease in pulmonary capillary wedge pressure (P=0.052, P=0.000004, P=0.000002, respectively) and improved dyspnoea score in the 7.5, 15, and 30 ng/kg/min ularitide group (P=0.0026, P=0.0026, P=0.0013, respectively). Ularitide reduced systemic vascular resistance and increased cardiac index for the 15 and 30 ng/kg/min groups (P=0.017, P=0.00002, respectively). Systolic blood pressure (BP) decreased dose dependency. Heart rate and serum creatinine were unchanged through day 3. Most frequently reported drug-related adverse events through day 3 in all ularitide groups were dose-dependent BP decrease and hypotension. Conclusion Ularitide lowered cardiac filling pressures and improved dyspnoea without apparent early deleterious effects on renal function in DHF patients. These results suggest that ularitide may play a role in the management of DHF.

The main task of atrial natriuretic peptide (ANP) in the kidney is the induction of natriuresis and diuresis, but the mechanism behind these effects is far from being clarified. The involvement of ANP in the regulation of the cardiovascular system is well established, but its regulatory role in transport processes in the nephron is still unresolved. Here, we take a closer look at the regulation of a variety of transport proteins in the renal nephron by ANP from the proximal tubule to the cortical and inner medullary collecting duct.

Pre-Clinical background Natriuretic peptides were identified as regulatory diureticnatriuretic substances responsible for salt and water homeostasis and as hormones lowering blood pressure. Urodilatin is a natriuretic peptide type A which is synthesized in the kidney and generated from the prohormone ANP-1-126. While the circulating ANP-99-126 is synthesized in the heart atrium and processed during exocytosis Urodilatin (ANP-95-126) is differentially processed in the kidney and detected only in urine.

OBJECTIVE:To show the effectiveness of an integrated therapeutical approach in a severe case of acute respiratory distress syndrome (ARDS) following burns, inhalation injury with therapy-refractory oxygenation under maximized ventilatory settings, and an overall complicated clinical course.PATIENT AND METHODS:Case report of a patient with severe inhalation injury and burns in an intensive care unit setting, undergoing cardiopulmonary resuscitation (CPR), nitric oxide (NO)-inhalation, surfactant-, kinetic-, and urodilatin-therapy.CASE REPORT:A 15-year-old male presented with deep dermal and full thickness thermal injuries involving 25% of his total body surface area. Shortly after presentation, the patient developed therapy-refractory respiratory failure, cardiac arrest, and subsequently suffered five-organ system failure (lung, heart, gastrointestinal, liver, kidney), in addition to burn injury, and ischemia related cerebral lesions. The patient was successfully treated with cardiac resuscitation, extra corporeal membrane oxygenation (ECMO), NO, kinetic therapy, surfactant, urodilatin, and other standard intensive care regimens. Three months post-trauma the patient was discharged home, nearly fully recovered.CONCLUSIONS:In a patient with severe ARDS, oxygenation failure under maximized ventilatory settings, and subsequent five-organ system failure, an integrated therapeutical approach comprising ECMO, NO, kinetic therapy, surfactant, and urodilatin did cross-bridge respiratory and vital functions, enabling overall survival.

From the *Lower Saxony Institute for Peptide Research (IPF), D-30625 Hannover, Germany; the * TheodorKocher Institute, University of Bern, CH-3012 Bern, Switzerland; the ~ Department of Anatomy, Medical School, D-30625 Hannover, Germany, IIBoehringer Mannheim Ltd., D-82377 Penzberg, Germany; the 82 of Pediatric Hematology and Oncology, Medical School, D-30625 Hannover, Germany; and the **Department of Anatomy, University of Zurich, CH-8057 Ziirich, Switzerland

Background: Natriuretic peptides regulate Na+ and H2O transport in the cortical collecting duct (CCD). We have shown that natriuretic peptides have no effect on ion conductances or water transport of principal cells (PC) even though a cGMP-regulated K+ channel is located in the basolateral membrane of these cells. Methods: RT-PCR was used to screen for different guanylyl cyclases (GC) in CCD and to look for the expression of GC-1 and GC-A mRNA in CCD of male and female Wistar and Sprague-Dawley rats. Polyclonal antibodies were raised against the detected GC. BCECF was used to investigate the effects of ANP on intracellular pH in intercalated cells (IC). Results: GC-A and GC-1 were detected. GC-A was immunolocalized in the luminal membrane of IC while GC-I was mainly found in the luminal membrane of PC. GC-1 is expressed in Sprague-Dawley and Wistar rats except for male Sprague-Dawley rats, while GC-A is expressed in all strains. ANP (160 nM, n = 11), urodilatin (140 nM, n = 6), which had no effect in PC, significantly decreased pH(i) by 0.02 +/-0.01 and 0.03 +/-0.01 Units in IC, respectively. ANP as well as urodilatin and 8-Br-cGMP decreased the pH, recovery after acidification by 30 +/-6% (n=12), 37 +/-7% (n=8), and 19 +/-3% (n=8), respectively. Conclusion: GC-A is located in the luminal membrane of IC of rat CCD and ANP acts through this receptor when regulating pH, via an inhibition of the Na+/H+-exchanger. PC do not possess GC-A. GC-1 seems to be the only GC in these cells of most rat strains tested and therefore, it could be responsible for the regulation of K+ channels in the basolateral membrane via cGMP-dependent protein kinase. (C) 2000 Elsevier Science BY. All rights reserved.

Gastrin stimulates gastric acid secretion by acting on the cholecystokinin B/gastrin receptor (CCK-BR). The localization of this receptor at the cellular level showed conflicting results in animal studies and has not been described in man by immunohistochemistry. The aim of the present study is to characterize the precise cellular location of the CCK-BR in the human stomach. Polyclonal antisera were raised against different epitopes of the CCK-BR molecule and used for immunohistochemical investigations. CCK-BR mRNA was detected in paraffin tissue sections by the highly sensitive method of in situ reverse transcriptase-polymerase chain reaction (RT-PCR). Using immunohistochemistry, CCK-BR could successfully be localized in gastric parietal cells. In the majority of parietal cells, CCK-BR immunoreactivity was present at the basolateral cell membrane domain. In some parietal cells, a granular pattern of immunoreactivity was exclusively confined to the cytoplasm of the cells. CCK-BR mRNA was found in parietal cells and in enterochromaffin-like (ECL) cells by means of in situ RT-PCR. No expression of CCK-BR was found in the gastric antral mucosa. Our data support the concept that gastrin stimulates gastric acid secretion directly via CCK-B receptors on parietal cells and indirectly by inducing histamine release from histamine-containing ECL cells, which contributes to acid secretion by parietal cells.

In immortalized human kidney epithelial (IHKE-1) cells derived from proximal tubules, two natriuretic peptide receptors (NPR) were identified. In addition to NPR-A, which is bound by atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and urodilatin (URO), a novel form of NPR-B that might be bound by C-type natriuretic peptide (CNP) was identified using PCR. This novel splice variant of NPR-B (NPR-Bi) was also found in human kidney. Whereas ANP, BNP, and URO increased intracellular cGMP levels in IHKE-1 cells in a concentration-dependent manner, CNP had no effect on cGMP levels. To determine the physiologic responses to these agonists in IHKE-1 cells, the membrane voltage (Vm) was monitored using the slow whole-cell patch-clamp technique. ANP (10 nM), BNP (10 nM), and URO (16 nM) depolarized these cells by 3 to 4 mV (n = 47, 7, and 16, respectively), an effect that could be mimicked by 0.1 mM 8-Br-cGMP (n = 15). The effects of ANP and 8-Br-cGMP were not additive (n = 4). CNP (10 nM) also depolarized these cells, by 3+/-1 mV (n = 28), despite the absence of an increase in cellular cGMP levels, indicating a cGMP-independent mechanism. In the presence of CNP, 8-Br-cGMP further depolarized Vm significantly, by 1.6+/-0.3 mV (n = 5). The depolarizations by ANP were completely abolished in the presence of Ba2+ (1 mM, n = 4) and thus can be related to inhibition of a K+ conductance in the luminal membrane of IHKE-1 cells. The depolarizations attributable to CNP were completely blocked when genistein (10 microM, n = 6), an inhibitor of tyrosine kinases, was present. These findings indicate that natriuretic peptides regulate electrogenic transport processes via cGMP-dependent and -independent pathways that influence the Vm of IHKE-1 cells.