Endothelin Receptor Inhibitors Research Articles

Comparison of efficacy between clazosentan and fasudil hydrochloride-based management of vasospasm after subarachnoid hemorrhage focusing on older and WFNS grade V patients: a single-center experience in Japan.

Subarachnoid hemorrhage often leads to poor outcomes owing to vasospasm, even after successful aneurysm treatment. Clazosentan, an endothelin receptor inhibitor, has been proven to be an effective treatment for vasospasms in a Japanese randomized controlled trial. However, its efficacy in older patients (≥ 75 years old) and those with World Federation of Neurosurgical Societies (WFNS) grade V has not been demonstrated. We retrospectively evaluated the efficacy of clazosentan in older patients and those with WFNS grade V, using real-world data. Patients with subarachnoid hemorrhage treated before and after the introduction of clazosentan were retrospectively evaluated. The patients were categorized into two groups (clazosentan era versus pre-clazosentan era), in which vasospasm management and outcomes were compared. Vasospasms were managed with fasudil hydrochloride-based (pre-clazosentan era) or clazosentan-based treatment (clazosentan era). Seventy-eight patients were included in this study: the clazosentan era (n = 32) and pre-clazosentan era (n = 46). Overall, clazosentan significantly reduced clinical vasospasms (clazosentan era: 31.3% versus pre-clazosentan era: 60.9%, p = 0.01), delayed cerebral ischemia (DCI) (9.4% versus 39.1%, p = 0.004), and vasospasm-related morbidity and mortality (M/M) (3.1% versus 19.6%, p = 0.03). In subgroup analysis of older patients or those with WFNS grade V, no significant difference was observed in clinical outcomes, although both DCI and vasospasm-related M/M were lower in the clazosentan era. Clazosentan was more effective than fasudil-based management in preventing DCI and reducing vasospasm-related M/M. Clazosentan could be used safely in older patients and those with WFNS grade V, although clinical outcomes in these patients were comparable to those of conventional treatment.

Inhibiting Endothelin Receptors with Macitentan Strengthens the Bone Protective Action of RANKL Inhibition and Reduces Metastatic Dissemination in Osteosarcoma.

Simple SummaryThe efficacy of current osteosarcoma therapy is diminished by two adverse events, namely resistance to chemotherapy and metastatic dissemination. In recent decades, research has been devoted to reducing these adverse events. Inhibiting bone resorption has shown promising effects on metastatic dissemination and tumor growth, with, however, the formation of significant tumoral mineralized tissue. Endothelin signaling is implicated in activating the cell that forms the mineralized tissues, consequently the impact of inhibiting it alone and in combination with the inhibition of bone resorption was evaluated using osteosarcoma models. The results obtained showed that inhibiting endothelin signaling significantly reduced the formation of mineralized tumor tissue concomitantly to metastatic dissemination without affecting sensitivity to chemotherapy. This inhibition appears to be a promising new therapeutic tool in the fight against osteosarcoma.Current treatments for osteosarcoma, combining conventional polychemotherapy and surgery, make it possible to attain a five-year survival rate of 70% in affected individuals. The presence of chemoresistance and metastases significantly shorten the patient’s lifespan, making identification of new therapeutic tools essential. Inhibiting bone resorption has been shown to be an efficient adjuvant strategy impacting the metastatic dissemination of osteosarcoma, tumor growth, and associated bone destruction. Unfortunately, over-apposition of mineralized matrix by normal and tumoral osteoblasts was associated with this inhibition. Endothelin signaling is implicated in the functional differentiation of osteoblasts, raising the question of the potential value of inhibiting it alone, or in combination with bone resorption repression. Using mouse models of osteosarcoma, the impact of macitentan, an endothelin receptor inhibitor, was evaluated regarding tumor growth, metastatic dissemination, matrix over-apposition secondary to RANKL blockade, and safety when combined with chemotherapy. The results showed that macitentan has no impact on tumor growth or sensitivity to ifosfamide, but significantly reduces tumoral osteoid tissue formation and the metastatic capacity of the osteosarcoma. To conclude, macitentan appears to be a promising therapeutic adjuvant for osteosarcoma alone or associated with bone resorption inhibitors.

Pulmonary Hypertension in Children - New Insights of Diagnosis and Management

Abstract Pulmonary hypertension (PH) is a pathophysiological condition that includes multiple clinical situations and can complicate most cardiovascular and respiratory diseases1. Step by step diagnosis and reviewing contemporary treatment approaches would significantly impact the prognosis of pediatric patients with PH. Management of children with PH requires a multidisciplinary team with experience. PH is frequently associated with cardiac and pulmonary diseases with chronic hypoxia, obstructive respiratory disorders, chest malformations, pneumonia, acute respiratory distress, and can also develop during late phases of cystic fibrosis, bronchial asthma, bronchiectasis. Updated definition of PH at the world symposium (HTAP, Nice, 2018) includes values of pulmonary artery pressure >20 mmHg and using pulmonary vascular resistance (PVR) indexed to the body surface to identify pre-capillary PH, PVR≥3 WU×m2 5. Cardiac catheterization represents the gold standard in diagnosing PH, being the most precise method of measuring the blood pressure (BP) in the pulmonary artery and offering valuable information about cardiac output, arterial pressure, and the response to pulmonary vasodilators2,3. The specific modern treatment with endothelin receptor inhibitors significantly improves the disease's clinical course and brings better parameters at instrumental investigations8.

Endothelin-1-Mediated Drug Resistance in EGFR-Mutant Non-Small Cell Lung Carcinoma.

Progression on therapy in non-small cell lung carcinoma (NSCLC) is often evaluated radiographically, however, image-based evaluation of said therapies may not distinguish disease progression due to intrinsic tumor drug resistance or inefficient tumor penetration of the drugs. Here we report that the inhibition of mutated EGFR promotes the secretion of a potent vasoconstrictor, endothelin-1 (EDN1), which continues to increase as the cells become resistant with a mesenchymal phenotype. As EDN1 and its receptor (EDNR) is linked to cancer progression, EDNR-antagonists have been evaluated in several clinical trials with disappointing results. These trials were based on a hypothesis that the EDN1-EDNR axis activates the MAPK-ERK signaling pathway that is vital to the cancer cell survival; the trials were not designed to evaluate the impact of tumor-derived EDN1 in modifying tumor microenvironment or contributing to drug resistance. Ectopic overexpression of EDN1 in cells with mutated EGFR resulted in poor drug delivery and retarded growth in vivo but not in vitro. Intratumoral injection of recombinant EDN significantly reduced blood flow and subsequent gefitinib accumulation in xenografted EGFR-mutant tumors. Furthermore, depletion of EDN1 or the use of endothelin receptor inhibitors bosentan and ambrisentan improved drug penetration into tumors and restored blood flow in tumor-associated vasculature. Correlatively, these results describe a simplistic endogenous yet previously unrealized resistance mechanism inherent to a subset of EGFR-mutant NSCLC to attenuate tyrosine kinase inhibitor delivery to the tumors by limiting drug-carrying blood flow and the drug concentration in tumors. SIGNIFICANCE: EDNR antagonists can be repurposed to improve drug delivery in VEGFA-secreting tumors, which normally respond to TKI treatment by secreting EDN1, promoting vasoconstriction, and limiting blood and drug delivery.

Treatment with the endothelin receptor inhibitor bosentan alleviates the NAFLD-associated increased intrahepatic vascular resistance and reduces steatosis and liver damage in a rat model of early NAFLD

Treatment with the endothelin receptor inhibitor bosentan alleviates the NAFLD-associated increased intrahepatic vascular resistance and reduces steatosis and liver damage in a rat model of early NAFLD

Hypoxia augments NaHS-induced ANP secretion via KATP channel, HIF-1α and PPAR-γ pathway

It has been reported that sodium hydrosulfide (NaHS) stimulated high stretch induced-atrial natriuretic peptide (ANP) secretion via ATP sensitive potassium (KATP) channel. KATP channel is activated during hypoxic condition as a compensatory mechanism. However, whether NaHS affects ANP secretion during hypoxia remains obscure. The purpose of the present study is to discover the impact of NaHS on ANP secretion during hypoxia and to unravel its signaling pathway. Isolated beating rat atria were perfused with buffer exposed to different O2 tension (to 100% O2, normoxia; to 20% O2, hypoxia). The ANP secretion increased negatively correlated with O2 tension. NaHS (50 μM) did not show any significant effect on low stretch induced-ANP secretion in normoxic condition but augmented low stretch induced-ANP secretion in hypoxic condition. The augmentation of NaHS-induced ANP secretion during hypoxia was blocked by the pretreatment with KATP channel blocker (glibenclamide) and was enhanced by the pretreatment with KATP channel activator (pinacidil). Hypoxia increased the expression of PPAR-γ protein but did not change the expression of HIF-1α protein and eNOS phosphorylation. The NaHS-induced ANP secretion during hypoxia was also blocked by the pretreatment with HIF-1α inhibitor (2-methoxy- estradiol), PPAR−γ inhibitor (GW9662) but not by NOS inhibitor (L-NAME) and endothelin receptor inhibitor (bosentan). The intravenous infusion of NaHS increased plasma ANP level in monocrotaline-treated rats but not in sham rats. These results suggest that hypoxia augmented NaHS-induced ANP secretion partly through KATP channel, HIF-1α, and PPAR−γ pathway.

Antagonists to endothelin receptor type B promote apoptosis in human pulmonary arterial smooth muscle cells

AimsVascular remodeling results from aberrations in the balance between cell proliferation and death, which is seen in the obstructive vasculature of pulmonary arterial hypertension (PAH). Endothelin (ET)-1 has a potent proliferative activity on vascular smooth muscle cells, and ET receptor inhibitors are used to treat PAH; however, it remains unclear whether ET receptor inhibition contributes to the apoptosis of pulmonary arterial smooth muscle cells (PASMCs), another cause of pulmonary vascular remodeling. Main methodsCultured human PASMCs were treated with the ETA receptor antagonist BQ-123 (100μM), or the ETB antagonist A-192621 (1–100μM) or BQ-788 (1–100μM) for 48h. The cells were then incubated for another 24h with or without doxorubicin (DOX, 1μM), an anthracyclin antitumor antibiotic that promotes p53-mediated apoptosis. Cell viability and apoptosis were evaluated by MTT assays, caspase-3/7 activity assays, and Western blots for cleaved caspase-3 expression. Key findingsThe viability of PASMCs was significantly decreased by A-192621 and BQ-788, in a dose-dependent manner. A-192621 and BQ-788 significantly increased the caspase-3/7 activity and cleaved caspase-3 expression in PASMCs. The PASMCs' susceptibility to DOX-induced apoptosis was significantly higher in the presence of A-192621 and BQ-788 than with vehicle. However, BQ-123 did not affect these parameters. SignificanceBlockade of the ETB receptor increases the extent of apoptosis and susceptibility to DOX-induced apoptosis in PASMCs. Apoptosis caused by ETB receptor blockade in PASMCs may be one of the mechanisms by which vascular remodeling is reduced in ET receptor inhibitor-based PAH treatments.

OP0265 Anti-At1r and Anti-Etar Autoantibodies from Patients with SSC and their Agonistic Effects

BackgroundFunctional autoantibodies to angiotensin II type 1 receptor (AT1R) and endothelin 1 type A receptor (ETAR) are found in elevated levels in systemic sclerosis (SSc) and they show an association...

Bladder Cancer: Innovative Approaches Beyond the Diagnosis

Bladder carcinoma (BC) is the most common urinary malignant tumor. In the light of the unsuccessful current therapies and their side effects, new pharmacological strategies are needed. In addition to the well known therapeutic possibilities described in the first section, we focused our attention on very recent and innovative tools to approach this target (new drug candidates from epigenetic modulators to endothelin receptor inhibitors, improved technological formulations, active principles from plants, and dietary components). Then, in the last paragraph, we analyzed the etiology of recurrent BC, with particular attention to cellular microenvironment. In fact, the incidence of recurrence is up to 90%, and 25% of tumours show progression towards invasiveness.

The Endothelin-Integrin Axis Is Involved in Macrophage-induced Breast Cancer Cell Chemotactic Interactions with Endothelial Cells

Elevated macrophage infiltration in tumor tissues is associated with breast cancer metastasis. Cancer cell migration/invasion toward angiogenic microvasculature is a key step in metastatic spread. We therefore studied how macrophages stimulated breast cancer cell interactions with endothelial cells. Macrophages produced cytokines, such as interleukin-8 and tumor necrosis factor-α, to stimulate endothelin (ET) and ET receptor (ETR) expression in breast cancer cells and human umbilical vascular endothelial cells (HUVECs). ET-1 was induced to a greater extent from HUVECs than from breast cancer cells, resulting in a density difference that facilitated cancer cell chemotaxis toward HUVECs. Macrophages also stimulated breast cancer cell adhesion to HUVECs and transendothelial migration, which were repressed by ET-1 antibody or ETR inhibitors. The ET axis induced integrins, such as αV and β1, and their counterligands, such as intercellular adhesion molecule-2 and P-selectin, in breast cancer cells and HUVECs, and antibodies against these integrins efficiently suppressed macrophage-stimulated breast cancer cell interactions with HUVECs. ET-1 induced Ets-like kinase-1 (Elk-1), signal transducer and activator of transcription-3 (STAT-3), and nuclear factor-κB (NF-κB) phosphorylation in breast cancer cells. The use of inhibitors to prevent their phosphorylation or ectopic overexpression of dominant-negative IκBα perturbed ET-1-induced integrin αV and integrin β1 expression. The physical associations of these three transcriptional factors with the gene promoters of the two integrins were furthermore evidenced by a chromatin immunoprecipitation assay. Finally, our mouse orthotopic tumor model revealed an ET axis-mediated lung metastasis of macrophage-stimulated breast cancer cells, suggesting that the ET axis was involved in macrophage-enhanced breast cancer cell endothelial interactions.

SPOO2P, a botanical nutriceutical, inhibits in vitro aortic contractions and lowers blood pressure of anesthetized hypertensive rats

Elevated endothelin levels are associated with cardiovascular diseases, e.g., hypertension and chronic heart failure. Development of an endothelin receptor inhibitor is potentially beneficial for treating some cardiovascular diseases. SPOO2P (PhytoPharmacon, LLC, Durham, NC) is a purified botanical extract, containing both myriceric acids A and C. Myriceric acid A has been reported as a non‐peptide antagonist of endothelin A (ETA) receptors. The present study determined the effects of SPOO2P on in vitro aortic muscle contractions and on blood pressure of anesthetized rats. Contraction of aortic rings bathed with physiologic salt solution (37°C; gassed with carbogen) was measured with force displacement transducers coupled to Tissue Force Analyzers (Micromed, Louisville,KY). Hypertension was induced with nitro‐L‐arginine methyl ester (L‐NAME) administered in drinking water (1g/L) for 3 weeks. Topical SPOO2P (20‐100 µg/ml) antagonized aortic contractions elicited by endothelin‐1, phenylephrine, serotonin, KCl and NaF over in a dose dependent manner with maximal inhibition ranging from 60‐90%. The compound (100 mg/kg; oral gavage) also significantly reduced the mean arterial blood pressure (MAP) of control and L‐NAME hypertensive rats. We conclude that SPOO2P is a potentially useful anti‐hypertensive nutriceutical. [Support: University of Louisville Research Initiation Grant].

Effects of endothelin-1 on calcium-independent contraction of bovine trabecular meshwork

Endothelin-1 (ET-1) is known to induce contraction of trabecular meshwork (TM) and is probably involved in the pathogenesis of glaucoma. Calcium (Ca(2+))-independent contraction has been shown in TM, and its inhibition may represent an interesting way of influencing outflow facility, and thus intraocular pressure (IOP). This study investigates the role of ET-1 and its receptors ET-A and ET-B (ET-AR and ET-BR) in TM Ca(2+)-independent contractility. Isometric tension measurements of bovine TM (BTM) strips were performed using a force-length transducer system. Intra- and extracellular Ca(2+) buffering was achieved by means of EGTA and BAPTA-AM. Under Ca(2+)-free conditions, ET-1-induced contractility of TM was assessed also in the presence of the specific inhibitors for ET-AR and ET-BR, BQ123 and BQ788 respectively. In order to clarify the intracellular mediators of Ca(2+)-independent contractility induced by ET-1, TM contraction was further measured in the presence of Y-27632, a selective inhibitor of Rho-associated kinases (ROCKs). The expression of ROCK1 and of its activating protein RhoA in BTM cells was investigated using western blot analysis. ET-1 induced a significant contraction of native BTM after intra- and extracellular Ca(2+)-depletion (45% +/- 8% of the maximally inducible contraction). Both endothelin receptor inhibitors BQ123 and BQ788 significantly reduced TM Ca(2+)-independent contraction in response to ET-1 (8.4 +/- 3.3% and 20.3 +/- 4.8% respectively). In the presence of the ROCK inhibitor Y-27632, ET-1-induced contraction of TM under Ca(2+)-free conditions was almost completely abolished (4.3% +/- 1.7%, p < 0.001). A clear signal for RhoA at 24 kDa and ROCK1 at 160 kDa could be detected in lysates of native tissue and cultured BTM cells with western blot. This study shows evidence that a significant portion of ET-1-induced contraction of TM is Ca(2+)-independent. In this contraction pathway, both ET-AR and ET-BR are involved with RhoA and its kinases as intracellular mediators. Ca(2+)-independent contraction of TM in response to ET-1 may represent a specific target to modulate IOP.

Zukunftsaspekte der Therapie der pulmonalarteriellen Hypertonie

In addition to combination treatment of pulmonary artery hypertension (PHT) with currently available drug options (endothelin-receptor inhibitors, phosphodiesterase-5 inhibitors, prostanoids). Numerous new drugs of other substance groups are being tested in preclinical and clinical studies. Most of the newly tried drugs use previously identified mechanisms of action that are involved in the development and progression of the underlying vascular disease. This has led to a certain paradigm shift which, in addition to vasodilatation and anti-platelet aggregation treatment, increasingly focuses on antiproliferative effects with the aim of preventing or regressing vascular remodelling. Of particular interest in this connection are tyrosine kinase inhibitors, which inhibit the action of such peptide growth factors as platelet-derived growth factor. Imatinib, one of this class of action, has given promising results in experimental studies and several case reports. Another greatly promising approach in the treatment of PHT are activators and simulators of soluble guanylyl cyclase, which are also currently being investigated in clinical trials.

Sclérodermie systémique

Systemic sclerosis is a rare auto-immune disease that involves immune cells, fibroblasts and endothelial cells. Depending on the cutaneous extend, the sclerosis may be either limited or diffuse. Whatever the form, all are associated with a high risk of visceral involvement, particularly digestive, pulmonary, cardiac and renal, resulting in an increased risk of mortality. Sclerodactily and digital ulcers alter considerably the patients' quality of live. Regular visceral check-up, adequate use of calcium channel blockers, ACE inhibitors and proton pump inhibitors, and the development these past 15 years of new drugs such as prostacyclins and analogues, endothelin receptor inhibitors, improve the patients survival.

Antisense Homology Box-Derived Peptides Represent a New Class of Endothelin Receptor Inhibitors

Baranyi, L., W. Campbell, K. Ohshima, S. Fujimoto, M. Boros, J. Kaszaki and H. Okada. Antisense homology box-derived peptides represent a new class of endothelin receptor inhibitors. Peptides 19(2) 211–223, 1998.—Several peptides encoded by the sense and corresponding antisense DNA have been found to recognize and bind to each other. We developed software to search for sense-antisense regions within proteins taking into account the degeneracy of the genetic code, i.e., one amino acid can have several “antisense” counterparts. Using this approach, we searched endothelin receptor type A for intramolecular regions related in sense-antisense fashion. After locating these regions (termed “antisense homology boxes”), several corresponding peptides were synthesized. The four new ET A receptor fragment peptides ETR-P1 (“CALSVDRYRAVASW”), ETR-P3 (“QGIGPLITAIEI”), ETR-P4 (“IADNAERYSANLSSHV”) and ETR-P6 (“LNRRNGSLRIALSEHLKNRREVA”) reported here can inhibit ET-1 activity.

Endothelins and their role in hypertension

Endothelin is a naturally occurring polypeptide substance with potent vasoconstrictive actions. It is produced from endothelial as well as non-endothelial cells. There are three closely related isoforms: endothelin-1, −2 and −3 (ET1, ET2 and ET3). The receptors for endothelin have been isolated and their genes cloned. Two receptors, called ET A and ET B , and having different affinities for the different endothelin isoforms, are well characterized. The different distribution of endothelin receptors in various tissues is responsible for the multiplicity of actions attributed to endothelin. Endothelin released from endothelial cells has local paracrine and autocrine effects on smooth muscle cells. It appears to be contributory to the pathophysiology of systemic hypertension, atherosclerosis, myocardial ischaemia, left ventricular dysfunction and congestive heart failure, ventricular hypertrophy, renal failure and pulmonary hypertension. Elevations of endothelin in the blod may also be markers of disease. Active research and drug development programmes are evaluating endothelin receptor inhibitors and endothelin-converting enzyme inhibitors for the treatment of patients with various cardiovascular, cerebrovascular, pulmonary vascular and renal diseases. Available agents such as potassium ion channel openers, calcium entry blockers and angiotensin-converting enzyme inhibitors also interfere with endothelin activity.

Mechanism of anoxia-induced atrial natriuretic peptide release in the isolated rat atria.

Our laboratory has recently shown that locally produced endothelin (ET) is involved in the atrial natriuretic peptide (ANP) response to a physical stimulus, stretch. The aim of this study was to determine if factors locally produced in the atria were involved in the ANP response to a chemical stimulus, anoxia. Reduced oxygen tension is a potent stimulus of ANP release, and our results show that, when isolated perfused atria were exposed to anoxic conditions, the ANP secretion rate increased by a maximum of 129 +/- 8% of the baseline. Exposure to anoxia caused neither an elevation in perfusate creatinine phosphokinase, a change in atrial morphology detectable by electron microscopy, nor interfered with the return toward the baseline ANP secretion rate with reoxygenation, suggesting that this response was not due to myocyte damage. When the atria were pretreated with either 3 microM BQ-123, an endothelin receptor inhibitor, or 10 microM indomethacin, a cyclooxygenase inhibitor, the ANP response to anoxia was nearly abolished. To clarify the association between ET and prostaglandins, we showed that the ANP response to 50 nM ET-1 was totally blocked at both high and low pressure by 10 microM indomethacin, but the increased contractility response to ET was unaffected. Therefore, we have concluded that the anoxia-induced ANP response is mediated by locally produced ET, which, in turn, stimulates the production of prostaglandins. Prostaglandins appear to be responsible for the increased ANP secretion rate.

The antisense homology box: A new motif within proteins that encodes biologically active peptides

Amphiphilic peptides approximately fifteen amino acids in length and their corresponding antisense peptides exist within protein molecules. These regions (termed antisense homology boxes) are separated by approximately fifty amino acids. Because many sense-antisense peptide pairs have been reported to recognize and bind to each other, antisense homology boxes may be involved in folding, chaperoning and oligomer formation of proteins. The antisense homology box-derived peptide CALSVDRYRAVASW, a fragment of human endothelin A receptor, proved to be a specific inhibitor of endothelin peptide (ET-1) in a smooth muscle relaxation assay. The peptide was able to block endotoxin-induced shock in rats as well. Our finding of endothelin receptor inhibitor among antisense homology box-derived peptides indicates that searching proteins for this new motif may be useful in finding biologically active peptides.