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The evolution of antitumor therapies has significantly improved cancer prognosis but has concurrently resulted in cardiovascular toxicities. Understanding the biological mechanisms behind these toxicities is crucial for effective management. Immunotherapy-related cardiovascular toxicities are primarily mediated by immune cells and secreted cytokines. Chemotherapy may cause cardiovascular damage through autophagy disruption and mitochondrial dysfunction. Targeted therapies can induce toxicity through endothelin-1 (ET-1) production and cardiac signaling disruption. Radiotherapy may lead to cardiomyopathy and myocardial fibrosis by affecting endothelial cells, triggering inflammatory responses and accelerating atherosclerosis. This review provides insights into these mechanisms and strategies, aiming to enhance the clinical prevention and treatment of cardiovascular toxicities., Competing Interests: Declaration of interests The authors declare that there are no conflicts of interest., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The first endothelin (ET)-1 receptor antagonist was approved for clinical use over 20 years ago, but to date this class of compounds has been limited to treating pulmonary arterial hypertension, a rare disease. Translational research over the last 5 years has reignited interest in the ET system as a therapeutic target across the spectrum of cardiovascular diseases including resistant hypertension, microvascular angina and post-coronavirus disease 2019 conditions. Notable developments include approval of a new ET A receptor antagonist and, intriguingly, combining the actions of ET A and an angiotensin II type 1 receptor antagonist within the same novel small molecule. Combinations of ET receptor blockers with other drugs, including phosphodiesterase-5 inhibitors and sodium-glucose co-transporter-2 antagonists, may drive synergistic benefits with the prospect of alleviating side effects. These new therapeutic strategies have the potential to dramatically widen the scope of indications targeting the ET-1 pathway., (© 2023. Springer Nature Limited.)

Polycythemia and pulmonary hypertension are 2 human diseases for which better therapies are needed. Upregulation of hypoxia-inducible factor-2α (HIF-2α) and its target genes, erythropoietin (EPO) and endothelin-1, causes polycythemia and pulmonary hypertension in patients with Chuvash polycythemia who are homozygous for the R200W mutation in the von Hippel Lindau (VHL) gene and in a murine mouse model of Chuvash polycythemia that bears the same homozygous VhlR200W mutation. Moreover, the aged VhlR200W mice developed pulmonary fibrosis, most likely due to the increased expression of Cxcl-12, another Hif-2α target. Patients with mutations in iron regulatory protein 1 (IRP1) also develop polycythemia, and Irp1-knockout (Irp1-KO) mice exhibit polycythemia, pulmonary hypertension, and cardiac fibrosis attributable to translational derepression of Hif-2α, and the resultant high expression of the Hif-2α targets EPO, endothelin-1, and Cxcl-12. In this study, we inactivated Hif-2α with the second-generation allosteric HIF-2α inhibitor MK-6482 in VhlR200W, Irp1-KO, and double-mutant VhlR200W;Irp1-KO mice. MK-6482 treatment decreased EPO production and reversed polycythemia in all 3 mouse models. Drug treatment also decreased right ventricular pressure and mitigated pulmonary hypertension in VhlR200W, Irp1-KO, and VhlR200W;Irp1-KO mice to near normal wild-type levels and normalized the movement of the cardiac interventricular septum in VhlR200Wmice. MK-6482 treatment reduced the increased expression of Cxcl-12, which, in association with CXCR4, mediates fibrocyte influx into the lungs, potentially causing pulmonary fibrosis. Our results suggest that oral intake of MK-6482 could represent a new approach to treatment of patients with polycythemia, pulmonary hypertension, pulmonary fibrosis, and complications caused by elevated expression of HIF-2α.

Sex differences in the immune response can also affect the febrile response, particularly the fever induced by lipopolysaccharide (LPS). However, other pathogen-associated molecular patterns, such as zymosan A (Zym) and polyinosinic-polycytidylic acid (Poly I:C), also induce fever in male rats with a different time course of cytokine release and different mediators such as endothelin-1 (ET-1). This study investigated whether female sex hormones affect Zym- and Poly I:C-induced fever and the involvement of ET-1 in this response. The fever that was induced by Zym and Poly I:C was higher in ovariectomized (OVX) female rats compared with sham-operated female rats. Estrogen replacement in OVX females reduced Zym- and Poly I:C-induced fever. The ET B receptor antagonist BQ788 reversed the LPS-induced fever in cycling females but not in OVX females. BQ788 did not alter the fever that was induced by Zym or Poly I:C in either cycling or OVX females. These findings suggest that the febrile response in cycling females is lower, independently of the stimulus that is inducing it and is probably controlled by estrogen. Also, ET-1 seems to participate in the febrile response that was induced by LPS in males and cycling females but not in the LPS-induced fever in OVX females. Additionally, ET-1 was not involved in the febrile response that was induced by Zym or Poly I:C in females.

Background: Many fishes have been known for their good nutritional effects especially in the cardiovascular aspect. Some specific fish peptides have anti-hypertensive effects., Objective: In the present study, we hypothesized that the hexapeptide (MEVFVP) from flounder fish muscle can be a potent antihypertensive peptide, therefore, decided to perform this experiment., Methods: The peptide MEVFVP from flounder fish muscle (40 mg/kg) and vehicle were administered per os to spontaneously hypertensive rats (SHRs) (SHR-M and SHR-C, respectively). Additionally, plasma MEVFVP was measured serially before and after its oral administration to Sprague Dawley rats., Results: Blood pressures (BPs), especially systolic BP, in SHR rats were decreased around 3-6 hours after MEVFVP administration. Compared with SHR-C rats, endothelin-1 (ET-1) mRNA expression in multiple tissues, and plasma levels of ET-1, angiotensin II, and aldosterone were lower in SHR-M rats, whereas the phosphorylation of AMP-activated protein kinase (AMPK) was increased in the kidney of SHR-M rats. The administered peptide was not detected in rat plasma, while ex vivo incubation of the peptide in rat plasma caused its rapid degradation within minutes., Conclusion: Our results show that the MEVFVP has an antihypertensive effect by regulating renin- angiotensin-aldosterone system, ET-1 and AMPK despite its limited bioavailability., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Background: Experimental autoimmune encephalitis (EAE) and virally induced demyelinating disease are two major experimental model systems used to study human multiple sclerosis. Although endothelin-1 level elevation was previously observed in the CNS of mice with EAE and viral demyelinating disease, the potential role of endothelin-1 in the development of these demyelinating diseases is unknown., Methods and Results: In this study, the involvement of endothelin-1 in the development and progression of demyelinating diseases was investigated using these two experimental models. Administration of endothelin-1 significantly promoted the progression of both experimental diseases accompanied with elevated inflammatory T cell responses. In contrast, administration of specific endothelin-1 inhibitors (BQ610 and BQ788) significantly inhibited progression of these diseases accompanied with reduced T cell responses to the respective antigens., Conclusions: These results strongly suggest that the level of endothelin-1 plays an important role in the pathogenesis of immune-mediated CNS demyelinating diseases by promoting immune responses.

Traumatic brain injury (TBI) is induced by the immediate physical disruption of brain tissue. TBI causes disruption of the blood-brain barrier (BBB) and brain edema. In the cerebrospinal fluid (CSF) of TBI patients, endothelin-1 (ET-1) is increased, suggesting that ET-1 aggravates TBI-induced brain damage. In this study, the effect of bosentan (ET A /ET B antagonist) and ambrisentan (ET A antagonist) on BBB dysfunction and brain edema were examined in a mouse model of TBI using lateral fluid percussion injury (FPI). FPI to the mouse cerebrum increased the expression levels of ET-1 and ET B receptors. Administration of bosentan (3 or 15 mg/kg/day) and ambrisentan (0.1 or 0.5 mg/kg/day) at 6 and 24 h after FPI ameliorated BBB disruption and cerebral brain edema. Delayed administration of bosentan from 2 days after FPI also reduced BBB disruption and brain edema, while ambrisentan had no significant effects. FPI-induced expression levels of ET-1 and ET B receptors were reduced by bosentan, but not by ambrisentan. In cultured mouse astrocytes and brain microvessel endothelial cells, ET-1 (100 nM) increased prepro--ET-1 mRNA, which was inhibited by bosentan, but not by ambrisentan. FPI-induced alterations of the expression levels of matrix metalloproteinase-9, vascular endothelial growth factor-A, and angiopoietin-1 in the mouse cerebrum were reduced by delayed administration of bosentan, while ambrisentan had no significant effects. These results suggest that ET antagonists are effective in improving BBB disruption and cerebral edema in TBI patients and that an ET A /ET B non-selective type of antagonists is more effective., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The saphenous vein is the most commonly used bypass graft in patients with coronary artery disease. During routine coronary artery bypass, grafting the vascular damage inflicted on the vein is likely to stimulate the release of endothelin-1, a potent endothelium-derived vasoconstrictor that also possesses cell proliferation and inflammatory properties, conditions associated with vein graft failure. In both in vitro and in vivo studies, endothelin receptor antagonists reduce neointimal thickening. The mechanisms underlying these observations are multifactorial and include an effect on cell proliferation and cell/tissue damage. Much of the data supporting the beneficial action of endothelin-1 receptor antagonism at reducing intimal thickening and occlusion in experimental vein grafts were published over 20 years ago. The theme of the recent ET-16 conference in Kobe was "Visiting Old and Learning New". This short review article provides an overview of studies showing the potential of endothelin receptor antagonists to offer an adjuvant therapeutic approach for reducing saphenous vein graft failure and poses the question why this important area of research has not been translated from bench to bedside given the potential benefit for coronary artery bypass patients.

Activation of the vascular endothelin-1 (ET-1) system is a key abnormality in vascular dysfunction of human obesity, especially in patients developing complications, such as the metabolic syndrome, diabetes, and atherosclerosis. Vascular insulin resistance, an increased insulin-stimulated endothelial production of ET-1 combined with impaired nitric oxide availability, is the hallmark of obesity-related vasculopathy, but dysregulated adipokine release from obese adipose tissue may contribute to the predominance of ET-1-dependent vasoconstriction. ET-1, in turn, might determine unhealthy obese adipose tissue expansion, with visceral and perivascular adipose tissue changes driving the release of inflammatory cytokines and atherogenic chemokines. In addition, ET-1 might also play a role in the development of the metabolic complications of obesity. Studies have shown inhibition of lipoprotein lipase activity by ET-1, with consequent hypertriglyceridemia. Also, ET-1 in pancreatic islets seems to contribute to beta cell dysfunction, hence affecting insulin production and development of diabetes. Moreover, ET-1 may play a role in nonalcoholic steatohepatitis. Recent clinical trials using innovative design have demonstrated that antagonism of ET-type A receptors protects against some complications of obesity and diabetes, such as nephropathy. These findings encourage further investigation to evaluate whether targeting the ET-1 system could afford better protection against other consequences of the obesity epidemic.

Introduction:  Bosentan is an endothelin-1 receptor antagonist with anti-inflammatory, antioxidant, and antiproliferative effects. We aimed to evaluate its effects on lung tissue in a pulmonary contusion (PC) model., Materials and Methods:  The rats were randomly divided into five groups: PC3: PC evaluated on the 3rd day ( n  = 8), PC-B3: PC enteral bosentan 100 mg/kg/day, for 3 days ( n  = 8), PC7: PC evaluated on the 7th day ( n  = 7), PC-B7: PC 7 days bosentan 100 mg/kg/day, for 7 days ( n  = 8), C: control ( n  = 6). Unilateral lung contusion was created by dropping a metal weight onto the chest. The rats were sacrificed on the 3rd or the 7th days. The lung tissue was evaluated histopathologically for alveolar edema, congestion, and leukocyte infiltration, biochemically for malondialdehyde (MDA), superoxide dismutase (SOD), and nitric oxide (NO) levels, and immunohistochemically for inducible nitric oxide synthase (iNOS), endothelial nitric oxide synthase (eNOS), and apoptosis scores., Results:  Alveolar edema, congestion, and leukocyte infiltration scores were increased in all groups compared with the control group ( p  < 0.05) and decreased in bosentan-treated groups compared with the relevant nontreated groups ( p  < 0.05). Fibrosis was observed only in PC7 and PC-B7 groups. Bosentan did not have any effect on fibrosis development. iNOS and eNOS levels were higher in all groups compared with the control ( p  < 0.05) without a difference in the nontreated versus treated groups ( p  > 0.05). Bosentan treatment caused decreased MDA and increased SOD levels in comparison to the nontreated groups ( p  < 0.05). Tissue NO levels did not show any significant difference among groups. PC groups had higher levels of apoptosis compared with the control group ( p  < 0.05). The degree of apoptosis decreased in bosentan-treated groups compared with the nontreated groups ( p  < 0.05)., Conclusion:  PC causes progressive lung tissue damage. Bosentan reduced leukocyte infiltration and alveolar edema and congestion caused by PC. It also decreased MDA levels and increased SOD levels. Bosentan prevents tissue damage by inhibiting acute inflammatory response and reduces oxidative stress secondary to inflammation. It has therapeutic effects on apoptosis., Competing Interests: None declared., (Georg Thieme Verlag KG Stuttgart · New York.)

Objective: The aim of this study was to investigate the effect of microRNA-214-5p (miR-214-5p) on spinal cord injury (SCI) and to explore the mechanism of action in pathophysiological relevance., Materials and Methods: The model of SCI was successfully established in rats aged 6-8 weeks. The levels of the locomotor function recovery in rats of the miR-379-5p group and SCI group were detected one month later by Basso-Beattie-Bresnahan (BBB) locomotor rating scale. Biochemical indexes were measured by Western blotting and real time-PCR, respectively. In addition, rat astrocytes were cultured to verify the effect of miR-379-5p on activated astrocytes in vitro., Results: Compared with the SCI group, the rats in the miR-379-5p group showed prominent improvement in the locomotor function in vivo. MiR-379-5p attenuated the activation of astrocytes and significantly suppressed the expressions of the nerve growth inhibitors. Furthermore, the down-regulation of endothelin-1 (ET-1) ameliorated the spinal cord ischemia, thereby reducing apoptosis and oxidative stress. Compared with the pentylenetetrazol (PTZ) group, ET-1 and chondroitin sulfate poly-glycoprotein (CSPG) in miR-379-5p group decreased significantly in the astrocytes transfected with miR-214-5p in vitro., Conclusions: MiR-379-5p retarded the neurofilament regeneration block effect by inhibiting endothelin 1 and the expression of the astrocytes after SCI. Furthermore, it might relieve nerve structure destruction, resist oxidative stress, and inhibit apoptosis, eventually promoting functional recovery.

There is substantial research on the vasoactive peptide endothelin (ET)-1 in physiology, as well as in pathology. In fact, pathologically elevated levels of ET-1 have been found in several disease states, such as various cardiovascular diseases, different cancers, some neurodegenerative disorders, as well as in diabetes. Here, we describe and discuss ET-1, its importance in different diseases, and the potential therapeutic effects of ET-traps in the treatment of these diseases. Previous in vitro and in vivo research (in the diabetes disease space) demonstrated that ET-traps potently and significantly prevent the induction of different markers of diabetes-related pathology. This included induction of extracellular matrix (ECM) proteins (collagen 4α1 and fibronectin), which are pathologically elevated in diabetes. The ET-traps prevented induction of these and brought a significant return to non-diabetic levels. We also discuss the merits of using ET-traps over the currently used endothelin receptor antagonists (ERAs) and previously used therapeutic antibodies., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Endothelin-1 (ET-1) is a potent vasoconstrictor and proinflammatory peptide that is upregulated in obesity. Herein, we tested the hypothesis that ET-1 signaling promotes visceral adipose tissue (AT) inflammation and disrupts glucose homeostasis. We also tested if reduced ET-1 is a required mechanism by which exercise ameliorates AT inflammation and improves glycemic control in obesity. We found that 1 ) diet-induced obesity, AT inflammation, and glycemic dysregulation were not accompanied by significantly increased levels of ET-1 in AT or circulation in wild-type mice and that endothelial overexpression of ET-1 and consequently increased ET-1 levels did not cause AT inflammation yet impaired glucose tolerance; 2 ) reduced AT inflammation and improved glucose tolerance with voluntary wheel running was not associated with decreased levels of ET-1 in AT or circulation in obese mice nor did endothelial overexpression of ET-1 impede such exercise-induced metabolic adaptations; 3 ) chronic pharmacological blockade of ET-1 receptors did not suppress AT inflammation in obese mice but improved glucose tolerance; and 4 ) in a cohort of human subjects with a wide range of body mass indexes, ET-1 levels in AT, or circulation were not correlated with markers of inflammation in AT. In aggregate, we conclude that ET-1 signaling is not implicated in the development of visceral AT inflammation but promotes glucose intolerance, thus representing an important therapeutic target for glycemic dysregulation in conditions characterized by hyperendothelinemia. Furthermore, we show that the salutary effects of exercise on AT and systemic metabolic function are not contingent on the suppression of ET-1 signaling.

Aims: Endothelin-1 (ET-1) is associated with the pathophysiology of autosomal dominant polycystic kidney disease (ADPKD) via cyst progression. Elevated concentrations of ET-1 in ADPKD correlate with many phenotypic changes in the kidney such as renal cyst development, interstitial fibrosis, and glomerulosclerosis. In addition, an imbalance between renal ET A and ET B receptors possibly leads to more severe disease progression. The objective of this review is to determine whether evaluating the efficacy of these drugs in treatment of cystic kidney disease may be a worthwhile aim, as determined by results from animal and human models., Materials and Methods: PubMed/Medline, Embase, and Google Scholar databases were searched using the key words "endothelin, endothelin-1 antagonists, and autosomal dominant polycystic kidney disease". All animal and human studies describing the effects of endothelin and endothelin-1 antagonists in ADPKD subjects were included in the review., Results: Urinary ET-1 concentrations could serve as a noninvasive surrogate biomarker for kidney ET-1 levels, as it is inversely associated with eGFR, independent of age, sex, and blood pressure. Elevated urinary excretion of ET-1 may be a biomarker for early renal injury. Antagonization of ET-1 may hopefully be a novel therapy for slowing progression of kidney damage in ADPKD., Conclusion: Based on the literature reviewed in this manuscript, it is proposed that further research evaluating the efficacy of endothelin antagonists in treatment of cystic kidney disease is warranted. More human studies need to be performed with larger sample sizes. Therefore, the recommendation for treatment is inconclusive at this time.
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The SUR2B/Kir6.1 channel openers iptakalim and natakalim reverse cardiac remodeling and ameliorate endothelial dysfunction by re-establishing the balance between the nitric oxide and endothelin systems. In this study, we investigated the microRNAs (miRs) involved in the molecular mechanisms of SUR2B/Kir6.1 channel opening in chronic heart failure. Both iptakalim and natakalim significantly upregulated the expression of miR-1-3p, suggesting that this miR is closely associated with the therapeutic effects against chronic heart failure. Bioinformatic analysis showed that many of the 183 target genes of miR-1-3p are involved in cardiovascular diseases, suggesting that miR-1-3p plays a vital role in such diseases and vascular remodeling. Target gene prediction showed that miR-1-3p combines with the 3' untranslated region (UTR) of endothelin-1 (ET-1) mRNA. Iptakalim and natakalim upregulated miR-1-3p expression and downregulated ET-1 mRNA expression in vitro. The dual luciferase assay confirmed that there is a complementary binding sequence between miR-1-3p and the 3' UTR 158-165 sequence of ET-1 mRNA. To verify the effect of miR-1-3p on ET-1, lentiviral vectors overexpressing or inhibiting miR-1-3p were constructed for the transduction of rat primary cardiac microvascular endothelial cells. The results showed that natakalim enhanced the miR-1-3p level. miR-1-3p overexpression downregulated the expression of ET-1, whereas miR-1-3p inhibition had the opposite effect. Therefore, we verified that SUR2B/Kir6.1 channel openers could correct endothelial imbalance and ameliorate chronic heart failure through the miR-1-3p/ET-1 pathway in endothelial cells. Our study provides comprehensive insights into the molecular mechanisms behind the SUR2B/Kir6.1 channel's activity against chronic heart failure., (Copyright © 2018. Published by Elsevier Masson SAS.)

Background: Magnolol, a major bioactive component extracted from Magnolia officinalis, exerts several beneficial effects, such as anti-inflammatory and anti-hypertensive activities., Purpose: In this study, we investigated whether magnolol has a protective effect on pneumonectomy and monocrotaline-induced pulmonary arterial hypertension (PAH) in rats., Design/methods: The alterations of right ventricular (RV) hypertrophy, pulmonary vascular remodeling, histopathological parameters, and related gene expression and signaling pathways in lungs by magnolol treatment were studied in the PAH rats., Results: Administration of magnolol greatly ameliorated the characteristic features of PAH, including increased pulmonary arterial pressure, RV hypertrophy, and pulmonary vascular remodeling. Moreover, magnolol inhibited angiotensin-converting enzyme (ACE)/angiotensin II (Ang II)/Ang II type 1 receptor (AT-1R) cascade, whereas upregulates ACE2 in the lungs of PAH rats. The overexpression of endothelin-1 (ET-1) and ET A receptor occurred in the PAH rats was significantly attenuated by magnolol through inhibition of Akt/ERK1/2/GSK3β/β-catenin pathway. Compared with that of untreated PAH rats, higher expression of endothelial nitric oxide synthase, and lower expression of inducible nitric oxide synthase and O 2 - production in lungs were observed in magnolol-treated PAH rats., Conclusion: We demonstrated that treatment with magnolol reduces the development of PAH induced by pneumonectomy and monocrotaline in rats, and suppressing Ang II and ET-1-mediated processes may contribute to its protective effects. These findings suggest that magnolol may be a potential agent for PAH therapy., (Copyright © 2018 Elsevier GmbH. All rights reserved.)

Background: Hemorrhagic shock-induced changes in vascular reactivity appear organ-specific. In the present study, we examined the hypothesis that vascular reactivity induced by septic shock similarly displays organ-specific differences and is regulated by inducible nitric oxide synthase (iNOS) and endothelin-1 (ET-1)., Methods: Endotoxic shock was induced in rabbits by administration of lipopolysaccharide (LPS) (1 mg/kg), and organ specificity of vascular reactivity of superior mesenteric artery (SMA), celiac artery (CA), and left renal artery (LRA) as well as the potential involvement of iNOS and ET-1 examined., Results: Vascular reactivity of SMA, CA, and LRA was increased at the early stages and decreased at the late stages after LPS administration. Superior mesenteric artery showed the greatest decrease in vascular reactivity in response to norepinephrine (NE) (34.9%) and acetylcholine (Ach; 32.3%), followed by LRA (NE, 33.7%; Ach, 30.5%) and CA (NE, 16.2%), whereas the relaxation reactivity of CA in response to Ach was increased to 159%. The mRNA and protein levels of iNOS and ET-1 in SMA, CA, and LRA were not affected at the early stages of endotoxic shock after LPS administration but significantly increased at the late stages. Expression levels were higher in SMA than CA and LRA and negatively correlated with the decrease in vascular reactivity. The iNOS and ET-1 inhibitors, aminoguanidine (20 mg/kg) and PD-142893 (0.02 mg/kg), respectively, induced significant improvements in vascular reactivity and organ perfusion and stabilized the hemodynamic parameters in rabbits subjected to endotoxic shock., Conclusion: Changes in vascular reactivity during endotoxic shock are organ-specific. Differential expression patterns of iNOS and ET-1 in different blood vessels contribute to the organ specificity of vascular reactivity., Level of Evidence: Therapeutic study, level II.

The heavy impact of obesity on the development and progression of cardiovascular disease has sparked sustained efforts to uncover the mechanisms linking excess adiposity to vascular dysfunction. Impaired vasodilator reactivity has been recognized as an early hemodynamic abnormality in obese patients, but also increased vasoconstrictor tone importantly contributes to their vascular damage. In particular, upregulation of the endothelin (ET)-1 system, consistently reported in these patients, might accelerate atherosclerosis and its complication, given the pro-inflammatory and mitogenic properties of ET-1. In recent years, a number of gut hormones, in addition to their role as modulators of food intake, energy balance, glucose and lipid metabolism, and insulin secretion and action, have demonstrated favorable vascular actions. They increase the bioavailability of vasodilator mediators like nitric oxide, but they have also been shown to inhibit the ET-1 system. These features make gut hormones promising tools for targeting both the metabolic and cardiovascular complications of obesity, a view supported by recent large-scale clinical trials indicating that novel drugs for type 2 diabetes with cardiovascular potential may translate into clinically significant advantages. Therefore, there is real hope that better understanding of the properties of gut-derived substances might provide more effective therapies for the obesity-related cardiometabolic syndrome.

Chronic kidney disease (CKD) is a life-threatening disease arising as a frequent complication of diabetes, obesity and hypertension. Since it is typically undetected for long periods, it often progresses to end-stage renal disease. CKD is characterized by the development of progressive glomerulosclerosis, interstitial fibrosis and tubular atrophy along with a decreased glomerular filtration rate. This is associated with podocyte injury and a progressive rise in proteinuria. As endothelin-1 (ET-1) through the activation of endothelin receptor type A (ET(A)) promotes renal cell injury, inflammation, and fibrosis which finally lead to proteinuria, it is not surprising that ET(A) receptors antagonists have been proven to have beneficial renoprotective effects in both experimental and clinical studies in diabetic and non-diabetic CKD. Unfortunately, fluid retention encountered in large clinical trials in diabetic CKD led to the termination of these studies. Therefore, several advances, including the synthesis of new antagonists with enhanced pharmacological activity, the use of lower doses of ET antagonists, the addition of diuretics, plus simply searching for distinct pathological states to be treated, are promising targets for future experimental studies. In support of these approaches, our group demonstrated in adult subtotally nephrectomized Ren-2 transgenic rats that the addition of a diuretic on top of renin-angiotensin and ET(A) blockade led to a further decrease of proteinuria. This effect was independent of blood pressure which was normalized in all treated groups. Recent data in non-diabetic CKD, therefore, indicate a new potential for ET(A) antagonists, at least under certain pathological conditions.

Diabetes increases the risk and worsens the progression of cognitive impairment. The hippocampus is an important domain for learning and memory. We previously showed that endothelin-1 (ET-1) reduced diabetes-induced inflammation in hippocampal neurons, suggesting a neuroprotective effect. Given that neurons and endothelial cells within the neurovascular unit depend on each other for proper function, we investigated the effect of ET-1 on brain-derived neurotrophic factor (BDNF) synthesis, a key neurotrophin and prosurvival factor, in neuronal (HT22 hippocampal neurons) and brain microvascular endothelial (BMEC-5i) cells under normal and diabetes-mimicking (high glucose plus palmitate) conditions. Cells were treated with exogenous ET-1 or ET receptor antagonists including ET(B) receptor selective antagonist BQ788 (1 microM) or dual-receptor antagonist bosentan (10 microM). Mature (m)BDNF, proBDNF and caspase-3 levels were measured by Western blotting. Diabetic conditions reduced the prosurvival mBDNF/proBDNF ratio in both HT22 and BMEC-5i cells. Addition of exogenous ET-1 had no effect on the BDNF system in HT22 cells in diabetic conditions. Both HT22 and BMEC-5i cells had an increase in the mBDNF/proBDNF ratio when grown in diabetes-simulating conditions in the presence of endothelin receptor inhibition. These data suggest that blockade of ET-1 may provide neuroprotection to hippocampal cells through the modulation of the BDNF system.

Introduction: A number of studies indicate that endothelin-1 (ET-1) may act as an inflammatory cell "gatekeeper," by regulating the influx of neutrophils following pulmonary injury. To further examine the role of ET-1 in modulating lung inflammation, hamsters were treated with an endothelin receptor antagonist (ERA), HJP272, either 1 h prior to intratracheal instillation of amiodarone (AM) or 24 h afterwards., Methods: In both cases, the extent of lung injury and repair was determined by (1) histopathological changes; (2) neutrophil content in bronchoalveolar lavage fluid (BALF); (3) lung collagen content; (4) tumor necrosis factor receptor 1 expression by BALF macrophages; (5) BALF levels of (a) transforming growth factor beta-1, (b) stromal cell-derived factor 1 (commonly referred to as CXCL12), and (c) platelet-derived growth factor BB; (6) alveolar septal cell apoptosis., Results: For each parameter, pretreatment with HJP272 resulted in a significant reduction compared to AM alone, whereas post-treatment was either ineffective or produced only a marginally significant change, suggesting that the course of lung inflammation and repair is programmed at a very early stage., Conclusions: This finding may explain why ERAs are not an effective treatment for human pulmonary fibrosis. Nevertheless, they may be useful as an adjunct to therapeutic regimens involving drugs that have fibrogenic potential.

Arterial stiffness may contribute to the pathogenesis of hypertension. The goal of this study is to elucidate the role of Endothelin-1 (ET-1) in aortic stiffening-induced hypertension through ET A receptor activation. An increase in aortic stiffness was created by use of a non-constrictive restraint, NCR on the abdominal aortic surface. A group of rats underwent aortic NCR or sham operation for 12 weeks and were then treated with ET A receptor antagonist BQ-123 for 3 weeks. We found that 12 weeks of aortic NCR significantly increased pulse and mean pressure and altered peripheral flow pattern, accompanied by an increased serum ET-1 level (p < 0.05). The increase in aortic stiffness (evidenced by an elevated pulse wave velocity) caused hypertrophic structural remodeling and decreased arterial compliance, along with an impaired endothelial function in peripheral small arteries. BQ-123 treatment only partially attenuated peripheral arterial hypertrophy and restored arterial compliance, but completely recovered endothelium function, and consequently restored local flow and lowered blood pressure. Our findings underscore the hemodynamic coupling between aortic stiffening and peripheral arterial vessels and flow dynamics through an ET A -dependent mechanism. ET A receptor blockade may have therapeutic potential for improving peripheral vessel structure and function in the treatment of aortic stiffness-induced hypertension.

This review article is focused on the various facets of possible endothelin's role in glaucoma; involvement of endothelin in other ocular, in particular vascular, diseases is not specifically discussed. Endothelin is an ubiquitous molecule that occurs in practically all ocular tissues. Its primary physiological function is regulation of the blood vessel diameter and hence regulation of the blood supply in tissues. It is secreted locally, and exerts its effect also predominantly locally. This limits the value of venous blood sampling for estimation of the endothelin function in a particular patient, or in study cohorts as well. Endothelin is involved in the regulation of intraocular pressure, in the regulation of blood flow and in activation of retinal and optic nerve head astrocytes. All these functions are of high importance when it comes to pathogenesis of glaucoma. Possible future directions for glaucoma treatment should encompass pharmacological antagonism to endothelin, an avenue which is at present hindered by potentially serious side-effects of available endothelin-antagonists., Competing Interests: Die Autoren geben an, dass kein Interessenkonflikt besteht., (Georg Thieme Verlag KG Stuttgart · New York.)

Tissue-type plasminogen activator (tPA) is neurotoxic and exacerbates uncoupling of cerebral blood flow (CBF) and metabolism after stroke, yet it remains the sole FDA-approved drug for treatment of ischemic stroke. Upregulation of c-Jun-terminal kinase (JNK) after stroke contributes to tPA-mediated impairment of autoregulation, but the role of endothelin-1 (ET-1) is unknown. Based on the Glasgow Coma Scale, impaired autoregulation is linked to adverse outcomes after TBI, but correlation with hippocampal histopathology after stroke has not been established. We propose that given after stroke, tPA activates N-Methyl-D-Aspartate receptors (NMDA-Rs) and upregulates ET-1 in a JNK dependent manner, imparing autoregulation and leading to histopathology. After stroke, CBF was reduced in the hippocampus and reduced further during hypotension, which did not occur in hypotensive sham pigs, indicating impairment of autoregulation. Autoregulation and necrosis of hippocampal CA1 and CA3 neurons were further impaired by tPA, but were preserved by the ET-1 antagonist BQ 123 and tPA-A, 296-299 a variant that is fibrinolytic but does not bind to NMDA-Rs. Expression of ET-1 was increased by stroke and potentiated by tPA but returned to sham levels by tPA-A 296-299 and the JNK antagonist SP600125. Results show that JNK releases ET-1 after stroke. Tissue-type plasminogen activator -A 296-299 prevents impairment of cerebral autoregulation and histopathology after stroke by inhibiting upregulation of ET-1., (© 2017 Wiley Periodicals, Inc.)

Background: Preterm birth (PTB), defined as birth before 37 completed weeks of gestation, occurs in up to 18 percent of births worldwide and accounts for the majority of perinatal morbidity and mortality. While the single most common cause of PTB has been identified as inflammation, safe and effective pharmacotherapy to prevent PTB has yet to be developed., Methods: Our group has used an in vivo model of inflammation-driven PTB, biochemical methods, pharmacological approaches, a novel endothelin receptor antagonist that we synthesized and RNA knockdown to help establish the role of endothelin-1 (ET-1) in inflammation-associated PTB. Further, we have used our in vivo model to test whether sphingosine kinase, which acts downstream of ET-1, plays a role in PTB., Results: We have shown that levels of endothelin converting enzyme-1 (ECE-1) and ET-1 are increased when PTB is induced in timed pregnant mice with lipopolysaccharide (LPS) and that blocking ET-1 action, pharmacologically or using ECE-1 RNA silencing, rescues LPS-induced mice from PTB. ET-1 activates the sphingosine kinase/sphingosine-1-phosphate (SphK/S1P) pathway. S1P, in turn, is an important signaling molecule in the proinflammatory response. Interestingly, we have shown that SphK inhibition also prevents LPS-induced PTB in timed pregnant mice. Further, we showed that SphK inhibition suppresses the ECE-1/ET-1 axis, implicating positive feedback regulation of the SphK/S1P/ECE-1/ET-1 axis., Conclusion: The ET-1/SphK/SIP pathway is a potential pharmacotherapeutic target for the prevention of PTB., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

Patients with ischaemic heart disease or chronic heart failure show altered levels of obestatin, suggesting a role for this peptide in human heart function. We have previously demonstrated that GH secretagogues and the ghrelin gene-derived peptides, including obestatin, exert cardiovascular effects by modulating cardiac inotropism and vascular tone, and reducing cell death and contractile dysfunction in hearts subjected to ischaemia/reperfusion (I/R), through the Akt/nitric oxide (NO) pathway. However, the mechanisms underlying the cardiac actions of obestatin remain largely unknown. Thus, we suggested that obestatin-induced activation of PI3K/Akt/NO and PKG signalling is implicated in protection of the myocardium when challenged by adrenergic, endothelinergic or I/R stress. We show that obestatin exerts an inhibitory tone on the performance of rat papillary muscle in both basal conditions and under β-adrenergic overstimulation, through endothelial-dependent NO/cGMP/PKG signalling. This pathway was also involved in the vasodilator effect of the peptide, used both alone and under stress induced by endothelin-1. Moreover, when infused during early reperfusion, obestatin reduced infarct size in isolated I/R rat hearts, through an NO/PKG pathway, comprising ROS/PKC signalling, and converging on mitochondrial ATP-sensitive potassium [mitoK(ATP)] channels. Overall, our results suggest that obestatin regulates cardiovascular function in stress conditions and induces cardioprotection by mechanisms dependent on activation of an NO/soluble guanylate cyclase (sGC)/PKG pathway. In fact, obestatin counteracts exaggerated β-adrenergic and endothelin-1 activity, relevant factors in heart failure, suggesting multiple positive effects of the peptide, including the lowering of cardiac afterload, thus representing a potential candidate in pharmacological post-conditioning., (© 2017 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.)

Nitro-fatty acids are reactive signaling mediators that are formed when unsaturated fatty acids react with nitric oxide or nitric oxide-derived species. Nitro-fatty acids can modify specific signaling pathways via post-translational modifications of Cys residues in key regulatory proteins. One of the signaling cascades activated by nitro-fatty acids is the Keap1-Nrf2 pathway. We have previously studied the effects of nitro-oleic acid (OA-NO 2 ) on the human endothelial cell transcriptome. We observed that endothelin receptor B [ET-B (gene name EDNRB )], the receptor mediating the vasodilatory effects of endothelin-1 (ET-1) is induced by OA-NO 2 Inasmuch as ET-1 is one of the key regulators of vascular tone, we chose to examine in more detail the effect of OA-NO 2 on endothelin signaling in human endothelial cells. Nrf2 was found to regulate the OA-NO 2 -induced transcription of ET-B in human and mouse endothelial cells. Furthermore, chromatin immunoprecipitation analysis revealed that OA-NO 2 increased the binding of Nrf2 to an antioxidant response element in the enhancer region of the EDNRB gene. In addition, we show that the overexpression of both OA-NO 2 and Nrf2 substantially decreased and that Nrf2 silencing increased the ET-1 concentration in the culture media of endothelial cells. The change in the extracellular ET-1 concentration was dependent on ET-B receptor expression. These data suggest that OA-NO 2 modulates endothelin signaling by increasing Nrf2-dependent expression of the ET-B receptor in endothelial cells, which in turn mediates the decrease in extracellular ET-1 concentration. Based on these results, we propose that OA-NO 2 and Nrf2 may alleviate the vasoconstrictive effects of ET-1 by removing it from the circulation., (Copyright © 2017 by The American Society for Pharmacology and Experimental Therapeutics.)

Traditional Chinese medicine (TCM) preparations have significant effects on some refractory diseases; however, these compositions are complex and their mechanisms are unknown. Identification of the active components in these preparations is essential. The mortality rate for heart failure (HF) has been increasing in recent years, and myocardial dysfunction (MD) has been proved to be the pathological basis of HF. Yixinshu Capsule (YXSC) is a multi-component oral drug with therapeutic effects on HF. However, the key active components are still unclear. In this study, YXSC intestinal absorption liquid (IAL) was used and 62 compounds were identified by an analytical chemistry approach. Then, a compound - target - function network was established with a bioinformatics analysis tool. Finally, a cell model of MD on human-induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs) was used to verify the therapeutic effects of the active components of YXSC. Schisandrin A (Sch A) and schisandrin B (Sch B) were demonstrated to be the active components of YXSC by attenuating endothelin-1 (ET-1)-induced contraction dysfunction, brain natriuretic peptide (BNP) content elevation, and the morphological changes of hiPS-CMs. For the first time, our data illustrate the potent protective effects of Sch A and Sch B on ET-1-induced dysfunctional hiPS-CMs and revealed their effective targets and pathways. The integrative approach used in our study was applied to identify active components in TCM preparations and excavate the possible mechanisms.

Cold temperatures are associated with increased prevalence of hypertension. Cold exposure increases endothelin-1 (ET1) production. The purpose of this study is to determine whether upregulation of ET1 contributes to cold-induced hypertension (CIH). In vivo RNAi silencing of the ET1 gene was achieved by adeno-associated virus 2 (AAV2) delivery of ET1 short-hairpin small interfering RNA (ET1-shRNA). Four groups of male rats were used. Three groups were given AAV.ET1-shRNA, AAV.SC-shRNA (scrambled shRNA), and phosphate-buffered saline (PBS), respectively, before exposure to a moderately cold environment (6.7 ± 2°C), while the last group was given PBS and kept at room temperature (warm, 24 ± 2°C) and served as a control. We found that systolic blood pressure of the PBS-treated and SC-shRNA-treated groups increased significantly within 2 weeks of exposure to cold, reached a peak level (145 ± 4.8 mmHg) by 6 weeks, and remained elevated thereafter. By contrast, blood pressure of the ET1-shRNA-treated group did not increase, suggesting that silencing of ET1 prevented the development of CIH. Animals were euthanized after 10 weeks of exposure to cold. Cold exposure significantly increased the left ventricle (LV) surface area and LV weight in cold-exposed rats, suggesting LV hypertrophy. Superoxide production in the heart was increased by cold exposure. Interestingly, ET1-shRNA prevented cold-induced superoxide production and cardiac hypertrophy. ELISA assay indicated that ET1-shRNA abolished the cold-induced upregulation of ET1 levels, indicating effective silencing of ET1. In conclusion, upregulation of ET1 plays a critical role in the pathogenesis of CIH and cardiac hypertrophy. AAV delivery of ET1-shRNA is an effective therapeutic strategy for cold-related cardiovascular disease.

Background: Our previous study showed that the μ-opioid receptor agonist fentanyl citrate inhibits endothelin-1-and bradykinin-mediated pain responses in mice orthotopically inoculated with melanoma cells. We also demonstrated that bradykinin induces endothelin-1 secretion in melanoma cells. However, the analgesic mechanisms of fentanyl citrate remain unclear. Thus, the present study was conducted to determine whether fentanyl citrate affects bradykinin-induced endothelin-1 secretion in B16-BL6 melanoma cells., Methods: The amount of endothelin-1 in the culture medium was measured using an enzyme immunoassay. The expression of endothelin-1, kinin B 2 receptors, and μ-opioid receptors in B16-BL/6 melanoma cells was determined using immunocytochemistry., Results: Fentanyl citrate inhibited bradykinin-induced endothelin-1 secretion. The inhibitory effect of fentanyl citrate on the secretion of endothelin-1 was attenuated by the μ-opioid receptor antagonist naloxone methiodide. The immunoreactivities of endothelin-1, kinin B 2 receptors, and μ-opioid receptors in B16-BL6 melanoma cells were observed., Conclusion: These results suggest that fentanyl citrate regulates bradykinin-induced endothelin-1 secretion through μ-opioid receptors in melanoma cells., (Copyright © 2016 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.)

Temporal consequences of neurocompensation to balloon injury on endothelinergic functionality in rat contralateral carotid were evaluated. Rats underwent balloon injury in left carotid and were treated with CP-96345 (NK 1 antagonist). Concentration-response curves for endothelin-1 were obtained in contralateral (right) carotid at 2, 8, 16, 30, or 45 days after surgery in the absence or presence of BQ-123 (ET A antagonist), BQ-788 (ET B antagonist), or Tempol (superoxide-dismutase mimic). Endothelin-1-induced calcium mobilization was evaluated in functional assays carried out with BQ-123, BQ-788, or Tempol. Endothelin-1-induced NADPH oxidase-driven superoxide generation was measured by lucigenin chemiluminescence assays performed with BQ-123 or BQ-788. Endothelin-1-induced contraction was increased in contralateral carotid from the sixteenth day after surgery. This response was restored in CP-96345-treated rats. Endothelium removal or BQ-123 did not change endothelin-1-induced contraction in contralateral carotid. This response was restored by BQ-788 or Tempol. Contralateral carotid exhibited an increased endothelin-1-induced calcium mobilization, which was restored by BQ-788 or Tempol. Contralateral carotid exhibited an increased endothelin-1-induced lucigenin chemiluminescence, which was restored by BQ-788. We conclude that the NK 1 -mediated neurocompensatory response to balloon injury elicits a contractile hyperreactivity to endothelin-1 in rat contralateral carotid by enhancing the muscular ET B -mediated NADPH oxidase-driven generation of superoxide, which activates calcium channels.

Background/aims: Endothelin-1 is implicated in the pathogenesis of hypertension, but the underlying mechanisms remained elusive. Our previous study found that inhibition of mitochondrial fission of smooth muscle cells suppressed phenylephrine- and high K+-induced artery constriction. Here, we studied the effects of mitochondrial fission inhibitors on endothelin-1-induced vasoconstriction., Methods: The tension of rat mesenteric arteries and thoracic aorta was measured by using a multi-wire myograph system. Mitochondrial morphology of aortic smooth muscle cells was observed by using transmission electron microscopy., Results: Dynamin-related protein-1 selective inhibitor mdivi-1 relaxed endothelin-1-induced constriction, and mdivi-1 pre-treatment prevented endothelin-1-induced constriction of rat mesenteric arteries with intact and denuded endothelium. Mdivi-1 had a similar inhibitory effect on rat thoracic aorta. Another mitochondrial fission inhibitor dynasore showed similar effects as mdivi-1 in rat mesenteric arteries. Mdivi-1 inhibited endothelin-1-induced increase of mitochondrial fission in smooth muscle cells of rat aorta. Rho-associated protein kinase inhibitor Y-27632 which relaxed endothelin-1-induced vasoconstriction inhibited endothelin-1-induced mitochondrial fission in smooth muscle cells of rat aorta., Conclusion: Endothelin-1 increases mitochondrial fission in vascular smooth muscle cells, and mitochondrial fission inhibitors suppress endothelin-1-induced vasoconstriction., (© 2017 The Author(s). Published by S. Karger AG, Basel.)

Exposure to particulate matter air pollution has been causally linked to cardiovascular disease in humans. Several broad and overlapping hypotheses describing the biological mechanisms by which particulate matter exposure leads to cardiovascular disease have been explored, although linkage with specific factors or genes remains limited. These hypotheses may or may not also lead to particulate matter-induced cardiac dysfunction. Evidence pointing to autocrine/paracrine signaling systems as modulators of cardiac dysfunction has increased interest in the emerging role of endothelins as mediators of cardiac function following particulate matter exposure. Endothelin-1, a well-described small peptide expressed in the pulmonary and cardiovascular systems, is best known for its ability to constrict blood vessels, although it can also induce extravascular effects. Research on the role of endothelins in the context of air pollution has largely focused on vascular effects, with limited investigation of responses resulting from the direct effects of endothelins on cardiac tissue. This represents a significant knowledge gap in air pollution health effects research, given the abundance of endothelin receptors found on cardiac tissue and the ability of endothelin-1 to modulate cardiac contractility, heart rate, and rhythm. The plausibility of endothelin-1 as a mediator of particulate matter-induced cardiac dysfunction is further supported by the therapeutic utility of certain endothelin receptor antagonists. The present review examines the possibility that endothelin-1 release caused by exposure to PM directly modulates extravascular effects on the heart, deleteriously altering cardiac function., (Published by Elsevier Inc.)

Hyperinsulinemia is a hallmark of insulin resistance-associated metabolic disorders. Under physiological conditions, insulin maintains a balance between nitric oxide (NO) and, the potent vasoconstrictor, endothelin-1 (ET-1). We tested the hypothesis that acute hyperinsulinemia will preferentially augment ET-1 protein expression, disrupt the equilibrium between ET-1 expression and endothelial NO synthase (eNOS) activation, and subsequently impair flow-induced dilation (FID) in human skeletal muscle arterioles. Skeletal muscle biopsies were performed on 18 lean, healthy controls (LHCs) and 9 older, obese, type 2 diabetics (T2DM) before and during (120 min) a 40 mU/m 2 /min hyperinsulinemic-euglycemic (5 mmol/L) clamp. Skeletal muscle protein was analyzed for ET-1, eNOS, phosphorylated eNOS (p-eNOS), and ET-1 receptor type A (ETAR) and B (ETBR) expression. In a subset of T2DM (n = 6) and LHCs (n = 5), FID of isolated skeletal muscle arterioles was measured. Experimental hyperinsulinemia impaired FID (% of dilation at ∆60 pressure gradient) in LHCs (basal: 74.2 ± 2.0; insulin: 57.2 ± 3.3, P = 0.003) and T2DM (basal: 62.1 ± 3.6; insulin: 48.9 ± 3.6, P = 0.01). Hyperinsulinemia increased ET-1 protein expression in LHCs (0.63 ± 0.04) and T2DM (0.86 ± 0.06) compared to basal conditions (LHCs: 0.44 ± 0.05, P = 0.007; T2DM: 0.69 ± 0.06, P = 0.02). Insulin decreased p-eNOS (serine 1177) only in T2DM (basal: 0.28 ± 0.07; insulin: 0.17 ± 0.04, P = 0.03). In LHCs, hyperinsulinemia disturbed the balance between ETAR and ETBR receptors known to mediate vasoconstrictor and vasodilator actions of ET-1, respectively. Moreover, hyperinsulinemia markedly impaired plasma NO concentration in both LHCs and T2DM These data suggest that hyperinsulinemia disturbs the vasomotor balance in human skeletal muscle favoring vasoconstrictive pathways, eventually impairing arteriolar vasodilation., (© 2016 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.)

Background: Tubulointerstitial fibrosis, the final outcome of most kidney diseases, involves activation of epithelial mesenchymal transition (EMT). Endothelin-1 (ET-1) activates EMT in cancer cells, but it is not known whether it drives EMT in the kidney. We therefore tested the hypothesis that tubulointerstitial fibrosis involves EMT driven by ET-1., Methods and Results: Transgenic TG[mRen2]27 (TGRen2) rats developing fulminant angiotensin II-dependent hypertension with prominent cardiovascular and renal damage were submitted to drug treatments targeted to ET-1 and/or angiotensin II receptor or left untreated (controls). Expressional changes of E-cadherin and α-smooth muscle actin (αSMA) were examined as markers of renal EMT. In human kidney HK-2 proximal tubular cells expressing the ETB receptor subtype, the effects of ET-1 with or without ET-1 antagonists were also investigated. The occurrence of renal fibrosis was associated with EMT in control TGRen2 rats, as evidenced by decreased E-cadherin and increased αSMA expression. Irbesartan and the mixed ET-1 receptor antagonist bosentan prevented these changes in a blood pressure-independent fashion (P < 0.001 for both versus controls). In HK-2 cells ET-1 blunted E-cadherin expression, increased αSMA expression (both P < 0.01), collagen synthesis, and metalloproteinase activity (P < 0.005, all versus untreated cells). All changes were prevented by the selective ETB receptor antagonist BQ-788. Evidence for involvement of the Rho-kinase signaling pathway and dephosphorylation of Yes-associated protein in EMT was also found., Conclusions: In angiotensin II-dependent hypertension, ET-1 acting via ETB receptors and the Rho-kinase and Yes-associated protein induces EMT and thereby renal fibrosis., (© 2016 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.)

Objective: To study the effects of butylphthalide on bronchial asthma in guinea pigs, and investigate the involvement of endothelin., Methods: In guinea pigs, bronchial asthma was induced by injection of ovalbumin (OVA) and provoked by inhalation of OVA, and the effects of butylphthalide on asthma were evaluated through the changes it induced by OVA, pulmonary function, endothelin-1 (ET-1) contents and activity of endothelin converting enzyme-1 (ECE-1) in bronchoalveolar lavage fluid (BALF), serum and lung tissue, and the gene expression of ET-1 in lung tissue., Results: Butylphthalide significantly improved pulmonary function, lowered asthmatic behavior score, inhibited the activity of ECE-1, and reduced ET-1 gene expression level in lung tissue., Conclusions: Butylphthalide has an anti-asthma effect and the mechanisms involve inhibition of ECE-1 activity and lowering of ET-1geng expression.

Unlabelled: Endothelin 1 (ET-1) in addition to the vasoconstriction, also has mitogenic, proinflammatory and proagregation activities. The mediators of inflammatory responses are cytokines, including special role attributed to tumor necrosis factor (TNF-α)., Aim: The aim of this study was to evaluate the effect of ET-1 and its receptor blocker (BQ123) on the level of TNF-α in the brain rat., Materials and Methods: Experiments were performed on four groups of Wistar-Kyoto rats. Animals were divided into four groups of 8 rats. Group I - control was administered into the tail vein solution of 0.9 % NaCl. Group II - saline followed by ET-1 (3 μg/kg b.w.). Group III - saline followed by BQ123 (1 mg/kg b.w.). Group IV (BQ123/ET-1) - BQ123 (1 mg/kg b.w.) administered 30 min before ET-1 (3 μg/kg b.w.)., Results: Administration of ET-1 at doses of 3 μg/kg b.w. resulted in a statistically significant increase in TNF-α concentrations in brain homogenates compared to the control group (p<0.01). Administration of the ET(A) receptor blocker - BQ123 (1mg/kg b.w.) 30 min before administration of ET-1 significantly decreased in TNF-α concentrations in brain homogenates (p <0.01)., Conclusions: ET-1 is significantly increased in TNF-α levels in brain homogenates, while BQ123 given 30 min before administration of ET-1 caused a significant decrease in TNF-α levels, suggesting that its anti-inflammatory activity., (© 2016 MEDPRESS.)

Inhibition of the renin-angiotensin-aldosterone system (RAAS) plays a pivotal role in treatment of chronic kidney diseases (CKD). However, reversal of the course of CKD or at least long-term stabilization of renal function are often difficult to achieve, and many patients still progress to end-stage renal disease. New treatments are needed to enhance protective actions of RAAS inhibitors (RAASis), such as angiotensin-converting enzyme (ACE) inhibitors (ACEIs) or angiotensin receptor blockers (ARBs), and improve prognosis in CKD patients. Inhibition of endothelin (ET) system in combination with established RAASis may represent such an approach. There are complex interactions between both systems and similarities in their renal physiological and pathophysiological actions that provide theoretical rationale for combined inhibition. This view is supported by some experimental studies in models of both diabetic and nondiabetic CKD showing that a combination of RAASis with ET receptor antagonists (ERAs) ameliorate proteinuria, renal structural changes, and molecular markers of glomerulosclerosis, renal fibrosis, or inflammation more effectively than RAASis or ERAs alone. Practically all clinical studies exploring the effects of RAASis and ERAs combination in nephroprotection have thus far applied add-on designs, in which an ERA is added to baseline treatment with ACEIs or ARBs. These studies, conducted mostly in patients with diabetic nephropathy, have shown that ERAs effectively reduce residual proteinuria in patients with baseline RAASis treatment. Long-term studies are currently being conducted to determine whether promising antiproteinuric effects of the dual blockade will be translated in long-term nephroprotection with acceptable safety profile., (Copyright © 2016 the American Physiological Society.)

Importance: 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., Objective: To evaluate the efficacy of macitentan in reducing the number of new digital ulcers in patients with systemic sclerosis., Design, Setting, and Participants: 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., Interventions: 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)., Main Outcomes and Measures: 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., Results: 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., Conclusions and Relevance: 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., Trial Registration: clinicaltrials.gov Identifiers: NCT01474109, NCT01474122.

Methamphetamine is a potent psychostimulant drug of abuse that increases release and blocks reuptake of dopamine, producing intense euphoria, factors that may contribute to its widespread abuse. It also produces severe neurotoxicity resulting from oxidative stress, DNA damage, blood-brain barrier disruption, microgliosis, and mitochondrial dysfunction. Intracerebral hemorrhagic and ischemic stroke have been reported after intravenous and oral abuse of methamphetamine. Several studies have shown that methamphetamine causes vasoconstriction of vessels. This study investigates the effect of methamphetamine on endothelin-1 (ET-1) release in mouse brain endothelial cells by ELISA. ET-1 transcription as well as endothelial nitric oxide synthase (eNOS) activation and transcription were measured following methamphetamine treatment. We also examine the effect of methamphetamine on isolated cerebral arteriolar vessels from C57BL/6 mice. Penetrating middle cerebral arterioles were cannulated at both ends with a micropipette system. Methamphetamine was applied extraluminally, and the vascular response was investigated. Methamphetamine treatment of mouse brain endothelial cells resulted in ET-1 release and a transient increase in ET-1 message. The activity and transcription of eNOS were only slightly enhanced after 24 hr of treatment with methamphetamine. In addition, methamphetamine caused significant vasoconstriction of isolated mouse intracerebral arterioles. The vasoconstrictive effect of methamphetamine was attenuated by coapplication of the endothelin receptor antagonist PD145065. These findings suggest that vasoconstriction induced by methamphetamine is mediated through the endothelin receptor and may involve an endothelin-dependent pathway., (© 2015 Wiley Periodicals, Inc.)

Background/aims: Both endothelin-1 (ET-1) and the renin-angiotensin system (RAS) may play important roles in renal fibrosis in the obstructed kidney. However, there have been few clear demonstrations of a relationship between their activation and additive or synergistic roles in renal fibrosis. We investigated the protective roles and relationship between renal RAS and ET-1 in unilateral ureteral obstruction (UUO) mice., Methods: 8-week-old male C57BL/6 mice were divided into seven groups: sham, bosentan+sham, valsartan+sham, vehicle+UUO, bosentan+UUO, valsartan+UUO, and valsartan+bosentan+UUO. Valsartan and bosentan were administered orally using an NG tube (valsartan 10 mg/kg/day, bosentan 100 mg/kg/day for 8 days, after which the molecular and structural kidney parameters were evaluated. Bosentan treatment elevated plasma renin activity, renal renin, and AT1R expression in UUO mice., Results: Although valsartan decreased plasma ET-1 in these mice, it did not affect ET(A) or ET(B) in their kidneys. Co-treatment with valsartan and bosentan decreased ET-1 in these mice compared to the single treatments. Bosentan, but not valsartan, elevated eNOS expression in their kidneys. Co-treatment with valsartan and bosentan reduced TGF-β, α-SMA, and collagen IV expression, and the Masson's trichrome stained area in their kidneys., Conclusions: Bosentan and valsartan acted complementarily, and co-treatment with both drugs had an additive protective effect against renal fibrosis., (© 2016 The Author(s) Published by S. Karger AG, Basel.)

The anemia of sickle cell disease is associated with a severe inflammatory vasculopathy and endothelial dysfunction, which leads to painful and life-threatening clinical complications. Growing evidence supports the anti-inflammatory properties of ω-3 fatty acids in clinical models of endothelial dysfunction. Promising but limited studies show potential therapeutic effects of ω-3 fatty acid supplementation in sickle cell disease. Here, we treated humanized healthy and sickle cell mice for 6 weeks with ω-3 fatty acid diet (fish-oil diet). We found that a ω-3 fatty acid diet: (i) normalizes red cell membrane ω-6/ω-3 ratio; (ii) reduces neutrophil count; (iii) decreases endothelial activation by targeting endothelin-1 and (iv) improves left ventricular outflow tract dimensions. In a hypoxia-reoxygenation model of acute vaso-occlusive crisis, a ω-3 fatty acid diet reduced systemic and local inflammation and protected against sickle cell-related end-organ injury. Using isolated aortas from sickle cell mice exposed to hypoxia-reoxygenation, we demonstrated a direct impact of a ω-3 fatty acid diet on vascular activation, inflammation, and anti-oxidant systems. Our data provide the rationale for ω-3 dietary supplementation as a therapeutic intervention to reduce vascular dysfunction in sickle cell disease., (Copyright© Ferrata Storti Foundation.)

Purpose: The purpose was to measure the retinal venous pressure (RVP) in both eyes of primary open-angle glaucoma (POAG) patients before and 3 weeks after treatment with low-dosed Nifedipine., Methods: This retrospective study included 20 POAG patients who were treated with Nifedipine (5 mg daily) and 20 untreated control POAG patients. In both the treated and untreated control group, a distinction was made between those patients who had the Flammer-Syndrome (FS) and those who did not. The RVP was measured in all patients bilaterally at baseline and 3 weeks later by means of contact lens ophthalmodynamometry and the RVP measurements of the treated POAG patients were compared to the RVPs of the untreated POAG controls. Ophthalmodynamometry is done by applying an increasing force on the eye via a contact lens. The minimum force required to induce a venous pulsation is called the ophthalmodynamometric force (ODF). The RVP is defined and calculated as the sum of ODF and intraocular pressure (IOP) [RVP = ODF + IOP]., Results: The RVP decreased significantly after 3 weeks in both eyes of patients treated with low-dosed Nifedipine compared to the untreated group (mean decrease of 12.5 mmHg (SD 12.5), P < 0.001). A larger response to therapy was found in patients with the FS compared to patients lacking the FS (mean decrease of 16.07 vs. 7.28 mmHg, confidence Interval (CI): 5.2 to 9.3 vs. 12.3 to 19.7; P < 0.001). No significant differences were accounted for in the IOP's of the patients after treatment. In the untreated control group, no significant differences were accounted for either in the RVP or the IOP after 3 weeks., Conclusions: Treatment with low-dosed Nifedipine decreases RVP in both eyes of glaucoma patients, particularly in those with the Flammer-Syndrome. This effect may be due to the partial inhibition of Endothelin-1 (ET-1) by Nifedipine.

Nobiletin is a unique flavonoid having polymethoxy groups and has exhibited anti-inflammatory and antiobesity effects. Here, we examined the inhibition of nobiletin on melanogenesis induced by endothelin-1 (ET) and stem cell factor (SCF) in normal human melanocytes. Nobiletin dose dependently reduced ET plus SCF-stimulated tyrosinase activity without causing cytotoxicity. Nobiletin reduced cAMP-response element-binding protein (CREB) phosphorylation and microphthalmia-associated transcription factor (MITF) expression, which is a key transcription factor for tyrosinase expression in pigmentation induced by ET plus SCF stimulation. Nobiletin treatment effectively decreased ET plus SCF-induced Raf-1, MEK and ERK1/2 phosphorylation and also downregulated the forskolin-induced phosphorylation of CREB. Furthermore, nobiletin inhibited ET plus SCF-triggered production of melanin and expression of MITF/tyrosinase in a three-dimensional human epidermal model. In accordance with protein expression, the expression of genes related to the pigmentation was also increased in the cells stimulated with ET plus SCF and the cotreatment with nobiletin decreased obviously the ET plus SCF-triggered gene expressions of tyrosinase, PMEL, TRP1 and MITF. Nobiletin contributes to hypopigmentation by downregulating MITF and tyrosinase expression through reduced Raf-1 phosphorylation. Our findings implicate nobiletin as a potential new whitening agent., (© 2014 The American Society of Photobiology.)

Both endothelin-1 (ET-1) and high mobility group box 1 (HMGB1) reportedly are closely involved in the pathogenesis of acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). In this study, we explored the regulatory effects of ET-1 on the expression of HMGB1 in human bronchial epithelial cells (HBEpCs). Primary HBEpCs were treated with ET-1 with or without transcription inhibitor actinomycin D, ETA receptor blocker BQ123, ETB receptor blocker BQ788, focal adhesion kinase (FAK) inhibitor or shRNA, or different kinase inhibitors. ET-1 increased the HMGB1 mRNA level in a statistically significant dose- and time-dependent manner within 8 hours of treatment, which was reflected in the dose-dependent induction of the HMGB1 protein level and the FAK activity. BQ123 and FAK inhibitor or shRNA, but not BQ788, completely abolished the promoting effect of ET-1 on the expression of HMGB1. Luciferase reporter assays revealed that neither ET-1 nor ETA nor FAK inhibition had any significant effect on the HMGB1 gene promoter activity. In the presence of the transcription inhibitor actinomycin D, the HMGB1 mRNA level markedly decreased over time, and ET-1 dose-dependently rescued the HMGB1 mRNA level. This effect of ET-1 was completely abolished by BQ123 and FAK inhibitor or shRNA, but not by BQ788. In conclusion, this study provides the first evidence that ET-1 upregulates the expression of HMGB1 in HBEpCs by increasing the stability of HMGB1 mRNA via the ETA receptor by a FAK-dependent mechanism. It adds new insights into the molecular mechanisms underlying ALI/ARDS., (© 2015 S. Karger AG, Basel.)

Pulmonary hypertension (PH) is a rare and progressive disease characterized by an inflammatory status and vessel wall remodeling, resulting in increased pulmonary artery resistance. During the last decade, treatments have been proposed; most of them target the endothelial pathways that stimulate smooth muscle cell relaxation. However, PH remains associated with significant morbidity. We hypothesized that inflammation plays a crucial role in the severity of the abnormal vasoconstriction in PH. The goal of this study was to assess the effects of resolvin D1 (RvD1), a potent anti-inflammatory agent, on the pharmacological reactivity of human pulmonary arteries (HPAs) via an in vitro model of induced hyperreactivity. The effects of RvD1 and monoacylglyceride compounds were measured on contractile activity and Ca(2+) sensitivity developed by HPAs that had been pretreated (or not) under proinflammatory conditions with either 10 ng/ml TNF-α or 10 ng/ml IL-6 or under hyperreactive conditions with 5 nM endothelin-1. The results demonstrated that, compared with controls, 24-h pretreatment with TNF-α, IL-6, or endothelin-1 increased reactivity and Ca(2+) sensitivity of HPAs as revealed by agonist challenges with 80 mM KCl, 1 μM serotonin (5-hydroxytryptamine), 30 nM U-46619, and 1 μM phorbol 12,13-dibutyrate. However, 300 nM RvD1 as well as 1 μM monoacylglyceride-docosapentaenoic acid monoglyceride strongly reversed the overresponsiveness induced by both proinflammatory and hyperreactive treatments. In pretreated pulmonary artery smooth muscle cells, Western blot analyses revealed that RvD1 treatment decreased the phosphorylation level of CPI-17 and expression of transmembrane protein member 16A while increasing the detection of G protein-coupled receptor 32. The present data demonstrate that RvD1, a trihydroxylated docosahexaenoic acid derivative, decreases induced overreactivity in HPAs via a reduction in CPI-17 phosphorylation and transmembrane protein member 16A expression., (Copyright © 2014 the American Physiological Society.)

In type 2 diabetes patients, endothelin (ET) receptor blockade may enhance blood flow responses to exercise training. The combination of exercise training and ET receptor blockade may represent a more potent stimulus than training alone to improve vascular function, physical fitness and glucose homeostasis. We assessed the effect of an 8 week exercise training programme combined with either ET blockade or placebo on vasculature, fitness and glucose homeostasis in people with type 2 diabetes. In a double-blind randomized controlled trial, brachial endothelium-dependent and ‑independent dilatation (using flow-mediated dilatation and glyceryl trinitrate, respectively), glucose homeostasis (using Homeostasis Model Assessment for Insulin Resistance (HOMA-IR)) and physical fitness (maximal cycling test) were assessed in 18 men with type 2 diabetes (60 ± 6 years old). Subjects underwent an 8 week exercise training programme, with half of the subjects receiving ET receptor blockade (bosentan) and the other half a placebo, followed by reassessment of the tests above. Exercise training improved physical fitness to a similar extent in both groups, but we did not detect changes in vascular function in either group. This study suggests that there is no adaptation in brachial and femoral artery endothelial function after 8 weeks of training in type 2 diabetes patients. Endothelin receptor blockade combined with exercise training does not additionally alter conduit artery endothelial function or physical fitness in type 2 diabetes., (© 2014 The Authors. Experimental Physiology © 2014 The Physiological Society.)

Objective: To determine whether endothelin (ET)-1 vasoconstrictor tone is greater in overweight and obese adults with the metabolic syndrome (MetS)., Materials/methods: Forty overweight/obese middle-aged and older adults (age: 43-71 years; BMI: 25.1-36.9 kg/m²) were studied: 20 without MetS (13 M/7 F) and 20 with MetS (13 M/7 F). MetS was established according to NCEP ATP III guidelines. Forearm blood flow (FBF; plethysmography) responses to intra-arterial infusion of selective ET(A) receptor blockade (BQ-123; 100 nmol/min; for 60 min) and non-selective ET(A/B) receptor blockade (BQ-123 + BQ-788 [50 nmol/min for 60 min]) were determined., Results: In response to the selective ET(A) antagonism, there was a significant increase in forearm blood flow from baseline in both groups. However, the increase in forearm blood flow was significantly higher (P=0.03; ~45%) in the overweight/obese group with MetS than the group without MetS. In contrast, there were no significant group differences in FBF responses to non-selective ET(A/B) receptor blockade. Peak vasodilator responses to nonselective ET(A/B) blockade were ~50% higher than baseline blood flow in the overweight/obese groups without and with MetS., Conclusion: MetS is associated with higher ET-1 vasoconstrictor tone in overweight/obese adults. The enhanced ET-1 vasoconstrictor activity with MetS is mediated by the ET(A) receptor subtype., (Copyright © 2014 Elsevier Inc. All rights reserved.)