endothelin-1 and macitentan

Pulmonary Arterial hypertension (PAH) is a chronic and progressive disease characterized by an increase in pulmonary vascular resistance due to severe remodeling of the small pulmonary arteries. In PAH, the endothelial cells fail to maintain their homeostatic balance, with the consequent impaired production of vasodilators and over-expression of vasoconstrictors and proliferators. Current treatment of PAH is based on the discovery of three main pathways of endothelial dysfunction (prostacyclin, nitric oxide and endothelin-1), and includes drugs such as prostacyclin analogs, phosphodiesterase-5 inhibitors and endothelin receptor antagonists (ERAs). Recently approved drugs that act through these classic pathways include riociguat (cyclic GMP stimulator) and macitentan (a tissue specific dual ERA). However, several new drugs and new pathways are under study. New targeted therapies include tyrosine kinase inhibitors, Rho kinase inhibitors and serotonin receptor blockers. There are now ten drugs approved for the treatment of PAH that, alone or in combination, have changed the natural history of this disease. The new drugs will allow us to further modified the patients' life expectancy and move towards a cure.

Topics: Drug Therapy, Combination; Drugs, Investigational; Endothelin Receptor Antagonists; Endothelin-1; Epoprostenol; Humans; Hypertension, Pulmonary; Nitric Oxide; Phosphodiesterase 5 Inhibitors; Pyrimidines; Randomized Controlled Trials as Topic; Sulfonamides

Since the discovery of endothelin (ET)-1 in 1988, the main components of the signalling pathway have become established, comprising three structurally similar endogenous 21-amino acid peptides, ET-1, ET-2 and ET-3, that activate two GPCRs, ETA and ETB . Our aim in this review is to highlight the recent progress in ET research. The ET-like domain peptide, corresponding to prepro-ET-193-166 , has been proposed to be co-synthesized and released with ET-1, to modulate the actions of the peptide. ET-1 remains the most potent vasoconstrictor in the human cardiovascular system with a particularly long-lasting action. To date, the major therapeutic strategy to block the unwanted actions of ET in disease, principally in pulmonary arterial hypertension, has been to use antagonists that are selective for the ETA receptor (ambrisentan) or that block both receptor subtypes (bosentan). Macitentan represents the next generation of antagonists, being more potent than bosentan, with longer receptor occupancy and it is converted to an active metabolite; properties contributing to greater pharmacodynamic and pharmacokinetic efficacy. A second strategy is now being more widely tested in clinical trials and uses combined inhibitors of ET-converting enzyme and neutral endopeptidase such as SLV306 (daglutril). A third strategy based on activating the ETB receptor, has led to the renaissance of the modified peptide agonist IRL1620 as a clinical candidate in delivering anti-tumour drugs and as a pharmacological tool to investigate experimental pathophysiological conditions. Finally, we discuss biased signalling, epigenetic regulation and targeting with monoclonal antibodies as prospective new areas for ET research.

Topics: Antineoplastic Agents; Aspartic Acid Endopeptidases; Benzazepines; Bosentan; Endothelin A Receptor Antagonists; Endothelin-1; Endothelin-2; Endothelin-3; Endothelin-Converting Enzymes; Endothelins; Epigenesis, Genetic; Humans; Hypertension, Pulmonary; Metalloendopeptidases; Neoplasms; Peptide Fragments; Phenylpropionates; Pyridazines; Pyrimidines; Receptor, Endothelin B; Sulfonamides; Vasodilator Agents

It is well established that the endothelin, nitric oxide and prostacyclin pathways play an important role in the development of pulmonary arterial hypertension (PAH). Indeed, the therapeutic options currently available for the management of PAH all act on one of these mechanistic pathways. However, this is an exciting time for both clinicians and scientists, as increased understanding of the mechanisms involved in the pathogenesis and progression of PAH has resulted in the development of a number of novel therapeutic options. This article highlights how the introduction of new compounds such as macitentan, riociguat and selexipag, which act on the endothelin, nitric oxide and prostacyclin pathways, respectively, have the potential to further improve the prognosis for patients with PAH.

Topics: Acetamides; Animals; Antihypertensive Agents; Benzamides; Clinical Trials as Topic; Drugs, Investigational; Endothelin A Receptor Antagonists; Endothelin B Receptor Antagonists; Endothelin-1; Epoprostenol; Guanylate Cyclase; Humans; Hypertension, Pulmonary; Imatinib Mesylate; Lisuride; Nitric Oxide; Phosphodiesterase 5 Inhibitors; Piperazines; Protein Kinase Inhibitors; Pyrazines; Pyrazoles; Pyrimidines; Serotonin Antagonists; Sulfonamides

Digital ulcers in patients with systemic sclerosis are associated with pain and poor quality of life. Endothelin-1 promotes vasculopathy in systemic sclerosis after macitentan, an endothelin-1 blocker.. To evaluate the efficacy of macitentan in reducing the number of new digital ulcers in patients with systemic sclerosis.. Two international, randomized, double-blind, placebo-controlled trials (DUAL-1, DUAL-2) were conducted between January 2012 and February 2014. Participants were patients with systemic sclerosis and active digital ulcers at baseline. Target enrollment for each study was 285 patients.. Patients were randomized (1:1:1) to receive oral doses of 3 mg of macitentan, 10 mg of macitentan, or placebo once daily and stratified according to number of digital ulcers at baseline (≤3 or >3).. The primary outcome for each trial was the cumulative number of new digital ulcers from baseline to week 16. Treatment effect was expressed as the ratio between treatment groups.. In DUAL-1, among 289 randomized patients (mean age 51.2 years; 85.8% women), 226 completed the study. The adjusted mean number of new digital ulcers per patient over 16 weeks was 0.94 in the 3-mg macitentan group (n = 95) and 1.08 in the 10-mg macitentan group (n = 97) compared with 0.85 in the placebo group (n = 97) (absolute difference, 0.09 [95% CI, -0.37 to 0.54] for 3 mg of macitentan vs placebo and 0.23 [-0.27 to 0.72] for 10 mg of macitentan vs placebo). Among 265 patients randomized in DUAL-2 (mean age 49.6 years; 81.9% women), 216 completed the study. In DUAL-2, the adjusted mean number of new digital ulcers was 1.44 in the 3-mg macitentan group (n = 88) and 1.46 in the 10-mg macitentan group (n = 88) compared with 1.21 in the placebo group (n = 89) (absolute difference, 0.23 [95% CI, -0.35 to 0.82] for 3 mg of macitentan vs placebo and 0.25 [95% CI, -0.34 to 0.84] for 10 mg of macitentan vs placebo). Adverse events more frequently associated with macitentan than with placebo were headache, peripheral edema, skin ulcer, anemia, upper respiratory tract infection, diarrhea, and nasopharyngitis.. Among patients with systemic sclerosis and active ischemic digital ulcers, treatment with macitentan did not reduce new digital ulcers over 16 weeks. These results do not support the use of macitentan for the treatment of digital ulcers in this patient population.. clinicaltrials.gov Identifiers: NCT01474109, NCT01474122.

Topics: Administration, Oral; Double-Blind Method; Endothelin-1; Female; Fingers; Humans; Male; Middle Aged; Outcome Assessment, Health Care; Pyrimidines; Scleroderma, Systemic; Skin Ulcer; Sulfonamides

Macitentan is a novel dual endothelin (ET)-1 receptor antagonist to be used in patients with pulmonary arterial hypertension. This study aimed to assess the pharmacokinetics (PK) and pharmacodynamics (PD) of macitentan after administration of multiple doses to healthy Korean male subjects.. A randomized, double-blind, placebo-controlled, multiple-ascending dose study was performed in 30 healthy male subjects receiving oral macitentan (3, 10, or 30 mg) or placebo once daily for 10 days. Plasma concentrations of macitentan, its active metabolite ACT-13277, and ET-1 were evaluated. Safety and tolerability measurements were conducted throughout the study.. The concentration-time profile of macitentan was characterized by slow absorption (median time to maximum plasma concentration [t(max)] 9-10 h) and slow elimination (mean elimination half-life [t ½] 11-15 h). After repeated doses of 3, 10, and 30 mg of macitentan over the course of 10 days, the peak concentration (C(max)) increased as the dose increased and the area under the plasma concentration-time curve during the dosing interval (AUC(τ)) increased in a dose-proportional manner. Plasma concentrations showed approximately 1.5- to 1.9-fold accumulation on day 10 compared with day 1. ACT-132577 showed higher levels of exposure than macitentan, its mean half-life was 46-48 h, and it accumulated 7- to 12-fold. Macitentan increased plasma ET-1 concentrations at all doses tested and was well tolerated and elicited no serious adverse events.. Multiple oral doses of 3, 10, and 30 mg of macitentan were well tolerated in healthy Korean subjects, and its pharmacokinetics correlated positively with ET-1 concentrations.

Topics: Adult; Antihypertensive Agents; Asian People; Dose-Response Relationship, Drug; Double-Blind Method; Endothelin Receptor Antagonists; Endothelin-1; Humans; Hypertension, Pulmonary; Male; Middle Aged; Pyrimidines; Receptor, Endothelin A; Sulfonamides; Young Adult

This multiple-ascending-dose study investigated safety, tolerability, pharmacokinetics, and pharmacodynamics, of macitentan, a new endothelin receptor antagonist (ERA) with sustained receptor binding and enhanced tissue penetration properties compared to other ERAs. Healthy male subjects (n = 32) received once daily oral doses of macitentan (1 - 30 mg) or placebo for 10 days. Administration of macitentan was safe and well tolerated. Macitentan had no effect on bile salts, suggesting an improved liver safety profile. The multiple-dose pharmacokinetics of macitentan were dose-proportional and were characterized by a median tmax and apparent elimination half-life varying from 6.0 to 8.5 and 14.3 to 18.5 hours, respectively, for the different doses and minimal accumulation. ACT-132577, a metabolite with lower potency than macitentan, had a half-life of about 48 hours and accumulated approximately 8.5-fold. Compared to placebo, administration of macitentan caused a dose-dependent increase in plasma ET-1 with maximum effects attained at 10 mg. A small dose-dependent increase in the 6β-hydroxycortisol/cortisol urinary excretion ratio was observed, although there were no statistically significant differences between treatments including placebo. Effects of macitentan on cytochrome P450 enzyme 3A4 should be further evaluated in dedicated studies. The present results support investigation of macitentan in the management of pulmonary arterial hypertension and ET-1-dependent pathologies.

Topics: Adult; Bile Acids and Salts; Dose-Response Relationship, Drug; Double-Blind Method; Endothelin A Receptor Antagonists; Endothelin B Receptor Antagonists; Endothelin-1; Familial Primary Pulmonary Hypertension; Humans; Hydrocortisone; Hypertension, Pulmonary; Male; Middle Aged; Pyrimidines; Sulfonamides; Young Adult

To study the pharmacokinetics, pharmacodynamics, and tolerability of rising single doses of macitentan, an endothelin receptor antagonist, in healthy male subjects.. This double-blind, placebo-controlled study was performed in seven groups of eight healthy male subjects. Doses of 0.2, 1, 5, 25, 100, 300 and 600 mg or placebo (two subjects per group) were administered. Plasma macitentan and endothelin-1 and serum total bile salt concentrations were measured and analysed non-compartmentally. Plasma and urine were analysed qualitatively for the presence of metabolites and one of these, ACT-132577, was also measured quantitatively in plasma. Standard tolerability measurements were performed throughout the study.. Macitentan was slowly absorbed and, at a dose of 300 mg, the t(1/2) (95% confidence interval, CI) was 17.5 h (14.1, 21.8). The dose-proportionality coefficient β for C(max) (95% CI) was 0.83 (0.79, 0.87) indicating less than dose-proportional pharmacokinetics of macitentan. In plasma, a pharmacologically active oxidative depropyl metabolite, ACT-132577, was found whereas in urine two minor metabolites were detected. The t(1/2) of ACT-132577 (95% CI) was 65.6 h (53.1, 80.9). Macitentan dose-dependently increased endothelin-1 concentrations up to 2.2-fold (95% CI 1.4, 2.4) at a dose of 600 mg, but had no consistent effect on total bile salts. Macitentan was well tolerated up to and including a dose of 300 mg, the maximum tolerated dose. Headache, nausea and vomiting were dose-limiting adverse events.. The pharmacokinetic and tolerability profile of macitentan is consistent with a once-a-day dosing regimen and warrants further investigation in clinical studies.

Topics: Adult; Bile Acids and Salts; Dose-Response Relationship, Drug; Double-Blind Method; Drug Tolerance; Endothelin Receptor Antagonists; Endothelin-1; Humans; Male; Middle Aged; Placebos; Pyrimidines; Sulfonamides; Young Adult

PARP inhibitors (PARPi) have changed the treatment paradigm of high-grade serous ovarian cancer (HG-SOC). However, the impact of this class of inhibitors in HG-SOC patients with a high rate of TP53 mutations is limited, highlighting the need to develop combinatorial therapeutic strategies to improve responses to PARPi. Here, we unveil how the endothelin-1/ET-1 receptor (ET-1/ET-1R) axis, which is overexpressed in human HG-SOC and associated with poor prognosis, instructs HG-SOC/tumor microenvironment (TME) communication via key pro-malignant factors and restricts the DNA damage response induced by the PARPi olaparib. Mechanistically, the ET-1 axis promotes the p53/YAP/hypoxia inducible factor-1α (HIF-1α) transcription hub connecting HG-SOC cells, endothelial cells and activated fibroblasts, hence fueling persistent DNA damage signal escape. The ET-1R antagonist macitentan, which dismantles the ET-1R-mediated p53/YAP/HIF-1α network, interferes with HG-SOC/stroma interactions that blunt PARPi efficacy. Pharmacological ET-1R inhibition by macitentan in orthotopic HG-SOC patient-derived xenografts synergizes with olaparib to suppress metastatic progression, enhancing PARPi survival benefit. These findings reveal ET-1R as a mechanistic determinant in the regulation of HG-SOC/TME crosstalk and DNA damage response, indicating the use of macitentan in combinatorial treatments with PARPi as a promising and emerging therapy.

Topics: Carcinoma, Ovarian Epithelial; Cell Line, Tumor; Endothelial Cells; Endothelin-1; Female; Humans; Ovarian Neoplasms; Poly(ADP-ribose) Polymerase Inhibitors; Receptor, Endothelin A; Tumor Microenvironment; Tumor Suppressor Protein p53

Pulmonary hypertension (PH) causes cardiac hypertrophy in the right ventricle (RV) and eventually leads to RV failure due to persistently elevated ventricular afterload. We hypothesized that the mechanical stress on the RV associated with increased afterload impairs vasodilator function of the right coronary artery (RCA) in PH. Coronary vascular response was assessed using microangiography with synchrotron radiation (SR) in two well-established PH rat models, monocrotaline injection or the combined exposure to chronic hypoxia and vascular endothelial growth factor receptor blockade with Su5416 (SuHx model). In the SuHx model, the effect of the treatment with the nonselective endothelin-1 receptor antagonist (ERA), macitentan, was also examined. Myocardial viability was determined in SuHx model rats, using

Topics: Animals; Antihypertensive Agents; Coronary Angiography; Coronary Vessels; Disease Models, Animal; Endothelin Receptor Antagonists; Endothelin-1; Hypertrophy, Right Ventricular; Hypoxia; Indoles; Monocrotaline; Predictive Value of Tests; Pulmonary Arterial Hypertension; Pyrimidines; Pyrroles; Rats, Sprague-Dawley; Severity of Illness Index; Sulfonamides; Synchrotrons; Vasodilation; Ventricular Dysfunction, Right; Ventricular Function, Right; Ventricular Remodeling

Sunitinib is an oral small molecule multitargeted tyrosine kinase inhibitor, which is currently used to treat severe cancers. Clinical research has shown that patients treated with sunitinib develop hypertension. As soon as sunitinib-induced hypertension appears, it is usual to administer anti-hypertension agent. But this treatment may cause acute blood pressure fluctuation which may lead to additional cardiovascular risk. The aim of this study is to establish a mathematical model for managing sunitinib-induced hypertension and blood pressure fluctuation. A mechanism-based PK/PD model was developed based on animal experiments. Then this model was used to perform simulations, thus to propose an anti-hypertension indication, according to which the anti-hypertension treatment might yield relative low-level AUC and fluctuation of blood pressure. The simulation results suggest that the anti-hypertension agent may yield low-level AUC and fluctuation of blood pressure when relative ET-1 level ranges from -15% to 5% and relative NO level is more than 10% compared to control group. Finally, animal experiments were conducted to verify the simulation results. Macitentan (30 mg/kg) was administered based on the above anti-hypertension indication. Compared with the untreated group, the optimized treatment significantly reduced the AUC of blood pressure; meanwhile the fluctuation of blood pressure in optimized treatment group was 70% less than that in immediate treatment group. This work provides a novel model with potential translational value for managing sunitinib-induced hypertension.

Topics: Administration, Oral; Amlodipine; Animals; Antihypertensive Agents; Biomarkers; Blood Pressure; Endothelin-1; Homeostasis; Hypertension; Male; Models, Molecular; Nitric Oxide; Protein Kinase Inhibitors; Pyrimidines; Rats; Rats, Wistar; Sulfonamides; Sunitinib

Blood vessels and skeleton interact together. Endothelin-1 is a potent vasoconstrictor and also has an effect on bone metabolism. The dual antagonist to both endothelin-1 type A and B receptors, Macitentan, has been approved for clinical management of pulmonary arterial hypertension while little is known about the secondary effect of the drug on spine. We aimed to answer how vertebral bone mass responded to Macitentan treatment in mice.. Sixteen male balb/c mice at 6 months were randomly assigned into 2 groups. Vehicle and Macitentan were administrated via intraperitoneal injection to Control group and Treatment group, respectively, for 4 months. At sacrifice, plasma endothelin-1 was evaluated with ELISA and vertebral bone mass was evaluated with Microcomputed Tomography and histological analysis.. We found higher plasma endothelin-1 level (p<0.01) and less vertebral bone mass (p<0.05) in Treatment group compared to controls. Moreover, less osteoblasts and more osteoclasts were observed in the vertebral trabecular bone in the Treatment group compared to controls, by immunohistochemistry of the cell-specific markers.. Treatment with Macitentan is associated with significant lower vertebral bone mass and therefore the secondary effect of dual antagonists to endothelin-1 receptors on the skeleton should be monitored and investigated in clinical practice. Both osteoblasts and osteoclasts may be involved while the molecular mechanism needs to be further explored.

Topics: Animals; Bone Density; Cancellous Bone; Endothelin-1; Hypertension; Male; Mice; Mice, Inbred BALB C; Osteoblasts; Pilot Projects; Pyrimidines; Spine; Sulfonamides

Topics: Adaptor Proteins, Signal Transducing; Animals; Antineoplastic Agents; beta-Arrestin 1; Cell Line, Tumor; Cell Survival; Cystadenocarcinoma, Serous; Disease Models, Animal; Endothelin-1; Female; Gene Expression Regulation, Neoplastic; Guanine Nucleotide Exchange Factors; Humans; Mice, Nude; Mutation; Ovarian Neoplasms; Protein Serine-Threonine Kinases; Pyrimidines; Receptor, Endothelin A; rho GTP-Binding Proteins; rhoA GTP-Binding Protein; Signal Transduction; Sulfonamides; Transcription Factors; Tumor Suppressor Protein p53; Xenograft Model Antitumor Assays; YAP-Signaling Proteins

Topics: Animals; beta-Arrestin 1; Cystadenocarcinoma, Serous; Cytoskeleton; Endothelin A Receptor Antagonists; Endothelin-1; Female; Gene Expression Regulation, Neoplastic; Humans; Mice, Nude; Microfilament Proteins; Ovarian Neoplasms; Podosomes; Pyrimidines; Receptor, Endothelin A; rhoC GTP-Binding Protein; Sulfonamides; Xenograft Model Antitumor Assays

Endothelin receptor antagonists are approved for pulmonary arterial hypertension. Development of selective ET. Human isolated pulmonary (i.d. 5.5mm) and human radial (i.d. 3.23mm) artery ring segments were mounted in organ baths for isometric force measurement. Single concentration-contraction curves to endothelin-1 were constructed in the absence or presence of bosentan (1-10µM), macitentan (0.03-0.3µM) or ambrisentan (0.1-1µM).. All 3 endothelin antagonists caused competitive rightward shifts in the endothelin-1 concentration-response curves in both arteries. The Clark plot and analysis gave the following pK. Noting the maximum plasma levels attained from recommended oral doses of each antagonist in volunteers, the pK

Topics: Bosentan; Dose-Response Relationship, Drug; Endothelin Receptor Antagonists; Endothelin-1; Humans; Hypertension, Pulmonary; Phenylpropionates; Pulmonary Artery; Pyridazines; Pyrimidines; Radial Artery; Receptor, Endothelin A; Sulfonamides; Tissue Survival; Vasoconstriction

Pulmonary arterial hypertension is usually fatal due to right ventricular failure and is frequently associated with co-existing left ventricular dysfunction. Endothelin-1 is a powerful pro-fibrotic mediator and vasoconstrictor that is elevated in pulmonary arterial hypertension. Endothelin receptor blockers are commonly used as pulmonary vasodilators, however their effect on biventricular injury, remodeling and function, despite elevated isolated right ventricular afterload is unknown.. Elevated right ventricular afterload was induced by progressive pulmonary artery banding. Seven rabbits underwent pulmonary artery banding without macitentan; 13 received pulmonary artery banding + macitentan; and 5 did not undergo inflation of the pulmonary artery band (sham-operated controls).. Right and left ventricular collagen content was increased with pulmonary artery banding compared to sham-operated controls and ameliorated by macitentan. Right ventricular fibrosis signaling (connective tissue growth factor and endothelin-1 protein levels); extra-cellular matrix remodeling (matrix-metalloproteinases 2 and 9), apoptosis and apoptosis-related peptides (caspases 3 and 8) were increased with pulmonary artery banding compared with sham-operated controls and decreased with macitentan.. Isolated right ventricular afterload causes biventricular fibrosis, right ventricular apoptosis and extra cellular matrix remodeling, mediated by up-regulation of endothelin-1 and connective tissue growth factor signaling. These pathological changes are ameliorated by dual endothelin receptor blockade despite persistent elevated right ventricular afterload.

Topics: Animals; Apoptosis; Disease Models, Animal; Echocardiography; Endothelin-1; Extracellular Matrix; Fibrosis; Gene Expression; Heart Ventricles; Hemodynamics; Hypertension, Pulmonary; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Pyrimidines; Rabbits; Receptors, Endothelin; RNA, Messenger; Signal Transduction; Sulfonamides; Ventricular Dysfunction, Right; Ventricular Remodeling

Despite the increasing prevalence of heart failure with preserved ejection fraction (HFpEF) in humans, there remains no evidence-based therapies for HFpEF. Endothelin-1 (ET-1) antagonists are a possibility because elevated ET-1 levels are associated with adverse cardiovascular effects, such as arterial and pulmonary vasoconstriction, impaired left ventricular (LV) relaxation, and stimulation of LV hypertrophy. LV hypertrophy is a common phenotype in HFpEF, particularly when associated with hypertension.. In the present study, we found that ET-1 levels were significantly elevated in patients with chronic stable HFpEF. We then sought to investigate the effects of chronic macitentan, a dual ET-A/ET-B receptor antagonist, on cardiac structure and function in a murine model of HFpEF induced by chronic aldosterone infusion. Macitentan caused LV hypertrophy regression independent of blood pressure changes in HFpEF. Although macitentan did not modulate diastolic dysfunction in HFpEF, it significantly reduced wall thickness and relative wall thickness after 2 weeks of therapy. In vitro studies showed that macitentan decreased the aldosterone-induced cardiomyocyte hypertrophy. These changes were mediated by a reduction in the expression of cardiac myocyte enhancer factor 2a. Moreover, macitentan improved adverse cardiac remodeling, by reducing the stiffer cardiac collagen I and titin n2b expression in the left ventricle of mice with HFpEF.. These findings indicate that dual ET-A/ET-B receptor inhibition improves HFpEF by abrogating adverse cardiac remodeling via antihypertrophic mechanisms and by reducing stiffness. Additional studies are needed to explore the role of dual ET-1 receptor antagonists in patients with HFpEF.

Topics: Aged; Animals; Case-Control Studies; Collagen Type I; Connectin; Diastole; Echocardiography; Endothelin A Receptor Antagonists; Endothelin B Receptor Antagonists; Endothelin-1; Female; Heart; Heart Failure; Humans; Hypertrophy; Hypertrophy, Left Ventricular; In Vitro Techniques; Male; MEF2 Transcription Factors; Mice; Middle Aged; Myocytes, Cardiac; Pyrimidines; RNA, Messenger; Stroke Volume; Sulfonamides; Ventricular Dysfunction, Left; Ventricular Remodeling

High endothelin-1 (ET-1) and transforming growth factor-β (TGF-β) levels may induce in healthy endothelial cells (EC) an endothelial-to-mesenchymal transition (EndMT). The same cytokines are associated with fibrosis development in systemic sclerosis (SSc). Although EndMT has not been definitively shown in SSc, this process, potentially induced by a stimulatory loop involving these 2 cytokines, overexpressed in this disease might contribute to fibroblast accumulation in affected tissues. Macitentan (MAC), an ET-1 receptor antagonist interfering with this loop, might prevent EndMT and fibroblast accumulation.. EC, isolated from healthy controls (HC) and patients with SSc, were treated with ET-1 and TGF-β and successively analyzed for gene and protein expressions of endothelial and mesenchymal markers, and for Sma- and Mad-related (SMAD) phosphorylation. Further, in the supernatants, we evaluated ET-1 and TGF-β production by ELISA assay. In each assay we evaluated the ability of MAC to inhibit both the TGF-β and ET-1 effects.. We showed that both TGF-β and ET-1 treatments induced an activation of the EndMT process in SSc-EC as reported in HC cells. The ELISA assays showed a mutual TGF-β and ET-1 induction in both SSc-EC and HC-EC. A statistically significant increase of SMAD phosphorylation after treatment was observed in SSc-EC. In each assay, MAC inhibited both TGF-β and ET-1 effects.. Our work is the first demonstration in literature that SSc-EC, under the synergistic effect of TGF-β and ET-1, may transdifferentiate toward myofibroblasts, thus contributing to fibroblast accumulation. MAC, interfering with this process in vitro, may offer a new potential therapeutic strategy against fibrosis.

Topics: Adult; Biomarkers; Case-Control Studies; Cell Transdifferentiation; Cells, Cultured; Endothelial Cells; Endothelin-1; Enzyme-Linked Immunosorbent Assay; Female; Humans; Italy; Male; Pyrimidines; Reference Values; Scleroderma, Systemic; Sensitivity and Specificity; Statistics, Nonparametric; Sulfonamides; Transforming Growth Factor beta; Young Adult

Systemic sclerosis (SSc) is a complex and not fully understood autoimmune disease associated with fibrosis of multiple organs. The main effector cells, the myofibroblasts, are collagen-producing cells derived from the activation of resting fibroblasts. This process is regulated by a complex repertoire of profibrotic cytokines, and among them transforming growth factor beta (TGF-β) and endothelin-1 (ET-1) play a major role. In this paper we show that TGF-β and ET-1 receptors co-operate in myofibroblast activation, and macitentan, an ET-1 receptor antagonist binding ET-1 receptors, might interfere with both TGF-β and ET-1 pathways, preventing myofibroblast differentiation.. Fibroblasts isolated from healthy controls and SSc patients were treated with TGF-β and ET-1 and successively analyzed for alpha smooth muscle actin (α-SMA) and collagen (Col1A1) expression and for the Sma and Mad Related (SMAD) phosphorylation. We further tested the ability of macitentan to interfere with these process. Furthermore, we silenced ET-1 and endothelin-1 receptor A expression and evaluated the formation of an ET-1/TGF-β receptor complex by immunoprecitation assay.. We showed myofibroblast activation in SSc fibroblasts assessing the expression of α-SMA and Col1A1, after stimulation with TGF-β and ET-1. Macitentan interfered with both ET-1- and TGF-β-induced fibroblast activation. To explain this unexpected inhibitory effect of macitentan on TGF-β activity, we silenced ET-1 expression on SSc fibroblasts and co-immunoprecipitated these two receptors, showing the formation of an ET-1/TGF-β receptor complex.. During SSc, ET-1 produced by activated endothelia contributes to myofibroblast activation using TGF-β machinery via an ET-1/TGF-β receptor complex. Macitentan interferes with the profibrotic action of TGF-β, blocking the ET-1 receptor portion of the ET-1/TGF-β receptor complex.

Topics: Actins; Adult; Blotting, Western; Collagen Type I; Collagen Type I, alpha 1 Chain; Dermis; Endothelin A Receptor Antagonists; Endothelin-1; Female; Fibroblasts; Humans; Male; Middle Aged; Multiprotein Complexes; Phosphorylation; Pyrimidines; Receptor, Endothelin A; Receptors, Transforming Growth Factor beta; RNA Interference; Scleroderma, Systemic; Signal Transduction; Smad Proteins; Sulfonamides; Transforming Growth Factor beta1; Up-Regulation; Young Adult

Diabetes is known to cause alteration of the endothelin (ET) system. We have previously demonstrated that ETs regulate augmented production of extracellular matrix proteins causing structural alterations in type 1 diabetes. Here we investigated the effects of macitentan, an orally-active, tissue-targeting dual ET receptor antagonist on chronic complications in type 2 diabetes.. db/db mice and their age- and sex-matched controls were examined after 2 and 4 months of diabetes. Groups of diabetic animals were treated with oral macitentan (25mg/kg/day). The animals were monitored with respect to body weight and blood glucose. Urine analyses were performed for albumin. Cardiac hemodynamic studies were carried out. Renal, cardiac and retinal tissues were analyzed for ET-1, transforming growth factor-β1 (TGF-β1), vascular endothelial growth factor (VEGF), fibronectin (FN), extradomain B containing FN (EDB(+)FN) and collagen α-I (IV) mRNA. Cardiac atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) were measured. Protein expressions were measured by ELISA and Western blot. Microscopic analyses were performed in the kidneys.. Diabetic animals showed hyperglycemia, increased urinary albumin and augmented serum creatinine levels. Diabetes caused increased renal, cardiac and retinal ET-1, TGF-β1, VEGF, FN, EDB(+)FN, collagen α-I(IV) mRNA expression along with increased FN and collagen protein and NF-κB activation. Diabetic mice also demonstrated mesangial expansion, cardiac dysfunction and increased expression of ANP and BNP. Treatment with macitentan attenuated such abnormalities.. These experiments confirmed that ET system plays a significant role in the pathogenesis of chronic complications in type 2 diabetes. Such diabetes induced changes can be reduced macitentan therapy.

Topics: Animals; Blotting, Western; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Endothelin A Receptor Antagonists; Endothelin B Receptor Antagonists; Endothelin-1; Enzyme-Linked Immunosorbent Assay; Gene Expression Regulation; Kidney; Male; Mice; Myocardium; Pyrimidines; Retina; Sulfonamides; Time Factors

Two endothelin receptor antagonists (ERAs), bosentan and ambrisentan, are currently approved for the treatment of pulmonary arterial hypertension (PAH), a devastating disease involving an activated endothelin system and aberrant contraction and proliferation of pulmonary arterial smooth muscle cells (PASMC). The novel ERA macitentan has recently concluded testing in a Phase III morbidity/mortality clinical trial in PAH patients. Since the association and dissociation rates of G protein-coupled receptor antagonists can influence their pharmacological activity in vivo, we used human PASMC to characterize inhibitory potency and receptor inhibition kinetics of macitentan, ambrisentan and bosentan using calcium release and inositol-1-phosphate (IP(1)) assays. In calcium release assays macitentan, ambrisentan and bosentan were highly potent ERAs with K(b) values of 0.14 nM, 0.12 nM and 1.1 nM, respectively. Macitentan, but not ambrisentan and bosentan, displayed slow apparent receptor association kinetics as evidenced by increased antagonistic potency upon prolongation of antagonist pre-incubation times. In compound washout experiments, macitentan displayed a significantly lower receptor dissociation rate and longer receptor occupancy half-life (ROt(1/2)) compared to bosentan and ambrisentan (ROt(1/2):17 minutes versus 70 seconds and 40 seconds, respectively). Because of its lower dissociation rate macitentan behaved as an insurmountable antagonist in calcium release and IP(1) assays, and unlike bosentan and ambrisentan it blocked endothelin receptor activation across a wide range of endothelin-1 (ET-1) concentrations. However, prolongation of the ET-1 stimulation time beyond ROt(1/2) rendered macitentan a surmountable antagonist, revealing its competitive binding mode. Bosentan and ambrisentan behaved as surmountable antagonists irrespective of the assay duration and they lacked inhibitory activity at high ET-1 concentrations. Thus, macitentan is a competitive ERA with significantly slower receptor dissociation kinetics than the currently approved ERAs. Slow dissociation caused insurmountable antagonism in functional PASMC-based assays and this could contribute to an enhanced pharmacological activity of macitentan in ET-1-dependent pathologies.

Topics: Animals; Bosentan; Calcium; CHO Cells; Clinical Trials, Phase III as Topic; Cricetinae; Endothelin Receptor Antagonists; Endothelin-1; Familial Primary Pulmonary Hypertension; Humans; Hypertension, Pulmonary; Inositol Phosphates; Myocytes, Smooth Muscle; Phenylpropionates; Pulmonary Artery; Pyridazines; Pyrimidines; Receptors, Endothelin; Sulfonamides