Effect of endothelin-1 on the blood pressure response to acute hypoxia and hyperoxia in healthy young men.

Endothelin-1 (ET-1) and its receptors are linked to increases in sensitivity of the chemoreceptors to hypoxic stress and the development of hypertension in preclinical models. We hypothesized ET receptor antagonism would lower resting blood pressure (BP) as well as the acute BP response to chemoreflex stress. Twenty-four men (31 ± 5 years, 26 ± 3 kg/m2) completed two study visits (control, bosentan). On each visit, BP was assessed under three conditions: (1) normoxia (FiO2 0.21), (2) chemoreflex excitation via hypoxia (FiO2 0.05-0.21), (3) chemoreflex inhibition via hyperoxia (FiO2 1.00). Bosentan increased plasma ET-1 (0.94 ± 0.90 to 1.27 ± 0.62 pg/mL, p = 0.004), supporting receptor blockade. Resting diastolic (73 ± 5 to 69 ± 7 mmHg, p = 0.007) and mean (93 ± 7 to 88 ± 7 mmHg, p = 0.005) BP were reduced following bosentan compared to control with no change in systolic BP (p = 0.507). The mean BP response to both acute hypoxia (-0.48 ± 0.38 to -0.25 ± 0.31 mmHg/%, p = 0.004) and hyperoxia (area under the curve -93 ± 108 to -27 ± 66 AU, p = 0.018) were attenuated following bosentan. Acute ET receptor inhibition attenuates the rise in BP during chemoreflex excitation as well as the fall in BP during chemoreflex inhibition in healthy young men. These data support a role for ET-1 in control of resting BP, possibly through a chemoreceptor-mediated mechanism.

Efficacy and safety of macitentan in Fontan-palliated patients: 52-week randomized, placebo-controlled RUBATO phase 3 trial and open-label extension.

OBJECTIVES: The efficacy and safety of macitentan, an endothelin receptor antagonist, were assessed in Fontan-palliated patients over a 52-week, multicenter, randomized, placebo-controlled, double-blind trial (RUBATO-DB) and an open-label extension trial (RUBATO-OL). METHODS: Patients aged ≥12 years, New York Heart Association functional class II/III, underwent total cavopulmonary connection >1 year pre-screening and showed no signs of Fontan failure/clinical deterioration. In RUBATO-DB, primary efficacy endpoint was change in peak oxygen consumption (VO2) from baseline to week 16; secondary endpoints were change from baseline over 52 weeks in peak VO2 and change in mean count/minute of daily physical activity via accelerometer (PA-Ac) from baseline to week 16. Safety was assessed throughout both studies. RESULTS: In RUBATO-DB, 137 patients were randomized to macitentan 10 mg (n=68) or placebo (n=69); 92.7% completed 52-week double-blind treatment. At week 16, mean (SD) change in peak VO2 was -0.16 (2.86) versus -0.67 (2.66) mL/kg/min with macitentan versus placebo (median unbiased treatment difference estimate: 0.62 mL/kg/min [99% repeated confidence interval -0.62; 1.85], p=0.19). No treatment effect was observed in either of the secondary endpoints. During RUBATO-DB, most common adverse events with macitentan were headache, nasopharyngitis and pyrexia. Across RUBATO-DB and RUBATO-OL, most common adverse events were COVID-19, headache and fatigue. RUBATO-OL was prematurely discontinued as RUBATO-DB did not meet its primary or secondary endpoint. CONCLUSIONS: The primary endpoint of RUBATO-DB was not met; macitentan did not improve exercise capacity versus placebo in Fontan-palliated patients. Macitentan was generally well tolerated over long-term treatment.

Effect of aortic smooth muscle BK channels on mediating chronic intermittent hypoxia-induced vascular dysfunction.

Chronic intermittent hypoxia (CIH) can lead to vascular dysfunction and increase the risk of cardiovascular diseases, cerebrovascular diseases, and arterial diseases. Nevertheless, mechanisms underlying CIH-induced vascular dysfunction remain unclear. Herein, this study analyzed the role of aortic smooth muscle calciumactivated potassium (BK) channels in CIH-induced vascular dysfunction. CIH models were established in rats and rat aortic smooth muscle cells (RASMCs). Hemodynamic parameters such as mean blood pressure (MBP), diastolic blood pressure (DBP), and systolic blood pressure (SBP) were measured in rats, along with an assessment of vascular tone. NO and ET-1 levels were detected in rat serum, and the levels of ET-1, NO, eNOS, p-eNOS, oxidative stress markers (ROS and MDA), and inflammatory factors (IL-6 and TNF-α) were tested in aortic tissues. The Ca2+ concentration in RASMCs was investigated. The activity of BK channels (BKα and BKß) was evaluated in aortic tissues and RASMCs. SBP, DBP, and MBP were elevated in CIH-treated rats, along with endothelial dysfunction, cellular edema and partial detachment of endothelial cells. BK channel activity was decreased in CIH-treated rats and RASMCs. BK channel activation increased eNOS, p-eNOS, and NO levels while lowering ET-1, ROS, MDA, IL-6, and TNF-α levels in CIH-treated rats. Ca2+ concentration increased in RASMCs following CIH modeling, which was reversed by BK channel activation. BK channel inhibitor (Iberiotoxin) exacerbated CIH-induced vascular disorders and endothelial dysfunction. BK channel activation promoted vasorelaxation while suppressing vascular endothelial dysfunction, inflammation, and oxidative stress, thereby indirectly improving CIH-induced vascular dysfunction.

Sex-Specific Differences in Kidney Function and Blood Pressure Regulation.

Premenopausal women generally exhibit lower blood pressure and a lower prevalence of hypertension than men of the same age, but these differences reverse postmenopause due to estrogen withdrawal. Sexual dimorphism has been described in different components of kidney physiology and pathophysiology, including the renin-angiotensin-aldosterone system, endothelin system, and tubular transporters. This review explores the sex-specific differences in kidney function and blood pressure regulation. Understanding these differences provides insights into potential therapeutic targets for managing hypertension and kidney diseases, considering the patient's sex and hormonal status.

REACT: a randomized trial to assess the efficacy and safety of clazosentan for preventing clinical deterioration due to delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage.

OBJECTIVE: Ischemic complications account for significant patient morbidity following aneurysmal subarachnoid hemorrhage (aSAH). The Prevention and Treatment of Vasospasm with Clazosentan (REACT) study was designed to assess the safety and efficacy of clazosentan, an endothelin receptor antagonist, in preventing clinical deterioration due to delayed cerebral ischemia (DCI) in patients with aSAH. METHODS: REACT was a prospective, multicenter, randomized, double-blind, phase 3 study. Eligible patients had aSAH secured by surgical clipping or endovascular coiling, and had presented with thick and diffuse clot on admission CT scan. Patients were randomized (1:1 ratio) to 15 mg/hour intravenous clazosentan or placebo within 96 hours of the aSAH for up to 14 days, in addition to standard of care treatment including oral or intravenous nimodipine. The primary efficacy endpoint was the occurrence of clinical deterioration due to DCI up to 14 days after initiation of the study drug. The main secondary endpoint was the occurrence of clinically relevant cerebral infarction at day 16 after study drug initiation. Other secondary endpoints included clinical outcome assessed on the modified Rankin Scale (mRS) and the Glasgow Outcome Scale-Extended (GOSE) at week 12 post-aSAH. Imaging and clinical endpoints were centrally adjudicated. RESULTS: A total of 409 patients were randomized between February 2019 and May 2022 across 74 international sites. Three patients did not start study treatment and were not included in the analysis set. The occurrence of clinical deterioration due to DCI was 15.8% (32/202 patients) in the clazosentan group and 17.2% (35/204 patients) in the placebo group, and the difference was not statistically significant (relative risk reduction [RRR] 7.2%, 95% CI -42.6% to 39.6%, p = 0.734). A nonsignificant RRR of 34.1% (95% CI -21.3% to 64.2%, p = 0.177) was observed in clinically relevant cerebral infarcts treated with clazosentan (7.4%, 15/202) versus placebo (11.3%, 23/204). Rescue therapy was less frequently needed for patients treated with clazosentan compared to placebo (10.4%, 21/202 vs 18.1%, 37/204; RRR 42.6%, 95% CI 5.4%-65.2%). A nonsignificant relative risk increase of 25.4% (95% CI -10.7% to 76.0%, p = 0.198) was reported in the risk of poor GOSE and mRS scores with clazosentan (24.8%, 50/202) versus placebo (20.1%, 41/204) at week 12 post-aSAH. Treatment-emergent adverse events were similar to those reported previously. CONCLUSIONS: Clazosentan administered for up to 14 days at 15 mg/hour had no significant effect on the occurrence of clinical deterioration due to DCI. Clinical trial registration no.: NCT03585270 (ClinicalTrials.gov) EU clinical trial registration no.: 2018-000241-39 (clinicaltrialsregister.eu).

CD38/cADPR-mediated calcium signaling in a human myometrial smooth muscle cell line, PHM1.

Cyclic ADP-ribose (cADPR) has emerged as a calcium-regulating second messenger in smooth muscle cells. CD38 protein possesses ADP-ribosyl cyclase and cADPR hydrolase activities and mediates cADPR synthesis and degradation. We have previously shown that CD38 expression is regulated by estrogen and progesterone in the myometrium. Considering hormonal regulation in gestation, the objective of the present study was to determine the role of CD38/cADPR signaling in the regulation of intracellular calcium upon contractile agonist stimulation using immortalized pregnant human myometrial (PHM1) cells. Western blot, immunofluorescence, and biochemical studies confirmed CD38 expression and the presence of ADP-ribosyl cyclase (2.6 ± 0.1 pmol/mg) and cADPR hydrolase (26.8 ± 6.8 nmoles/mg/h) activities on the PHM1 cell membrane. Oxytocin, PGF2α, and ET-1 elicited [Ca2+]i responses, and 8-Br-cADPR, a cADPR antagonist significantly attenuated agonist-induced [Ca2+]i responses between 20% and 46% in average. The findings suggest that uterine contractile agonists mediate their effects in part through CD38/cADPR signaling to increase [Ca2+]i and presumably uterine contraction. As studies in humans are limited by the availability of myometrium from healthy donors, PHM1 cells form an in vitro model to study human myometrium.

Prognostic Value of Plasma Endothelin-1 in Predicting Worse Outcomes in Patients with Prediabetes and Diabetes and Stable Coronary Artery Diseases.

Background: Endothelin-1 (ET-1) is an endogenous vasoconstrictor implicated in coronary artery disease (CAD) and diabetes. This study aimed to determine the prognostic value of ET-1 in the patients with stable CAD under different glucose metabolism states. Methods: In this prospective, large-cohort study, we consecutively enrolled 7,947 participants with angiography-diagnosed stable CAD from April 2011 to April 2017. Patients were categorized by baseline glycemic status into three groups (normoglycemia, prediabetes, and diabetes) and further divided into nine groups by circulating ET-1 levels. Patients were followed for the occurrence of cardiovascular events (CVEs), including nonfatal myocardial infarction, stroke, and cardiovascular mortality. Results: Of the 7,947 subjects, 3,352, 1,653, and 2,942 had normoglycemia, prediabetes, and diabetes, respectively. Over a median follow-up of 37.5 months, 381 (5.1%) CVEs occurred. The risk for CVEs was significantly higher in patients with elevated ET-1 levels after adjustment for potential confounders. When patients were categorized by both status of glucose metabolism and plasma ET-1 levels, the high ET-1 levels were associated with higher risk of CVEs in prediabetes (adjusted hazard ratio [HR], 2.089; 95% confidence interval [CI], 1.151 to 3.793) and diabetes (adjusted HR, 2.729; 95% CI, 1.623 to 4.588; both P<0.05). Conclusion: The present study indicated that baseline plasma ET-1 levels were associated with the prognosis in prediabetic and diabetic patients with stable CAD, suggesting that ET-1 may be a valuable predictor in CAD patients with impaired glucose metabolism.

The role of venous capacity in fluid retention with endothelin A antagonism: Mathematical modelling of the RADAR trial.

BACKGROUND AND PURPOSE: Endothelin-1 (ET-1) receptor A (ETA) antagonists reduce proteinuria and prevent renal outcomes in chronic kidney disease (CKD) patients, but their utility has been limited because of associated fluid retention, resulting in increased heart failure risk. Understanding the mechanisms responsible for fluid retention could result in solutions that preserve renoprotective effects while mitigating fluid retention, but the complexity of the endothelin system has made identification of the underlying mechanisms challenging. APPROACH: We utilized a previously developed mathematical model of ET-1 kinetics, ETA receptor antagonism, kidney function, haemodynamics, and sodium and water homeostasis to evaluate hypotheses for mechanisms of fluid retention with ETA antagonism. To do this, we simulated the RADAR clinical trial of atrasentan in patients with type 2 diabetes and CKD and evaluated the ability of the model to predict the observed decreases in haematocrit, urine albumin creatinine ratio (UACR), mean arterial pressure (MAP), and estimated glomerular filtration rate (eGFR). BACKGROUND AND KEY RESULTS: An effect of ETA antagonism on venodilation and increased venous capacitance was found to be the critical mechanism necessary to reproduce the simultaneous decrease in both MAP and haematocrit observed in RADAR. CONCLUSIONS AND IMPACT: These findings indicate that fluid retention with ETA antagonism may not be caused by a direct antidiuretic effect within the kidney but is instead be an adaptive response to venodilation and increased venous capacity, which acutely tends to reduce cardiac filling pressure and cardiac output, and that fluid retention occurs in an attempt to maintain cardiac filling and cardiac output.

Effects of pulmonary surfactant combined with noninvasive positive pressure ventilation in neonates with respiratory distress syndrome.

BACKGROUND: Neonatal respiratory distress syndrome (NRDS) is one of the most common diseases in neonatal intensive care units, with an incidence rate of about 7% among infants. Additionally, it is a leading cause of neonatal death in hospitals in China. The main mechanism of the disease is hypoxemia and hypercapnia caused by lack of surfactant. AIM: To explore the effect of pulmonary surfactant (PS) combined with noninvasive positive pressure ventilation on keratin-14 (KRT-14) and endothelin-1 (ET-1) levels in peripheral blood and the effectiveness in treating NRDS. METHODS: Altogether 137 neonates with respiratory distress syndrome treated in our hospital from April 2019 to July 2021 were included. Of these, 64 control cases were treated with noninvasive positive pressure ventilation and 73 observation cases were treated with PS combined with noninvasive positive pressure ventilation. The expression of KRT-14 and ET-1 in the two groups was compared. The deaths, complications, and PaO2, PaCO2, and PaO2/FiO2 blood gas indexes in the two groups were compared. Receiver operating characteristic curve (ROC) analysis was used to determine the diagnostic value of KRT-14 and ET-1 in the treatment of NRDS. RESULTS: The observation group had a significantly higher effectiveness rate than the control group. There was no significant difference between the two groups in terms of neonatal mortality and adverse reactions, such as bronchial dysplasia, cyanosis, and shortness of breath. After treatment, the levels of PaO2 and PaO2/FiO2 in both groups were significantly higher than before treatment, while the level of PaCO2 was significantly lower. After treatment, the observation group had significantly higher levels of PaO2 and PaO2/FiO2 than the control group, while PaCO2 was notably lower in the observation group. After treatment, the KRT-14 and ET-1 levels in both groups were significantly decreased compared with the pre-treatment levels. The observation group had a reduction of KRT-14 and ET-1 levels than the control group. ROC curve analysis showed that the area under the curve (AUC) of KRT-14 was 0.791, and the AUC of ET-1 was 0.816. CONCLUSION: Combining PS with noninvasive positive pressure ventilation significantly improved the effectiveness of NRDS therapy. KRT-14 and ET-1 levels may have potential as therapeutic and diagnostic indicators.

EGR1 interacts with p-SMAD at the endothelin-1 gene promoter to regulate gene expression in TGFß1-stimulated IMR-90 fibroblasts.

Pulmonary fibrosis is a severe and progressive lung disease characterized by lung tissue scarring. Transforming growth factor beta 1 (TGFß1) is crucial in causing pulmonary fibrosis by promoting the activation of fibroblasts and their differentiation into myofibroblasts, which are responsible for excessive extracellular matrix deposition. This study aimed to identify genes activated by TGFß1 that promote fibrosis and to understand the regulatory pathway controlling myofibroblast. Endothelin-1 (ET-1) was identified as the top-ranking gene in the fibrosis-related gene set using quantitative PCR array analysis. TGFß1 upregulated EGR1 expression through the ERK1/2 and JNK1/2 MAPK pathways. EGR1 and p-SMAD2 proteins interacted with the ET-1 gene promoter region to regulate TGFß1-induced ET-1 expression in IMR-90 pulmonary fibroblasts. Mice lacking the Egr1 gene showed reduced ET-1 levels in a model of pulmonary fibrosis induced by intratracheal administration of bleomycin. These findings suggest that targeting EGR1 is a promising approach for treating pulmonary fibrosis, especially idiopathic pulmonary fibrosis, by affecting ET-1 expression and profibrotic reactions.

Recurrent endothelin-1 mediated vascular insult leads to cognitive impairment protected by trophic factor pleiotrophin.

Vascular dementia (VaD) is a complex neurodegenerative condition, with cerebral small vessel dysfunctions as the central role in its pathogenesis. Given the lack of suitable animal models to study the disease pathogenesis, we developed a mouse model to closely emulate the clinical scenarios of recurrent transient ischemic attacks (TIAs) leading to VaD using vasoconstricting peptide Endothelin-1(ET-1). We observed that administration of ET-1 led to blood-brain barrier (BBB) disruption and detrimental changes in its components, such as endothelial cells and pericytes, along with neuronal loss and synaptic dysfunction, resulting in irreversible memory loss. Further, in our pursuit of understanding potential interventions, we co-administered pleiotrophin (PTN) alongside ET-1 injections. PTN exhibited remarkable efficacy in preserving vital components of the BBB, including endothelial cells and pericytes, thereby restoring BBB integrity, preventing neuronal loss, and enhancing memory function. Our findings give a valuable framework for understanding the detrimental effects of multiple TIAs on brain health and provide a useful animal model to explore VaD's underlying mechanisms further and pave the way for promising therapies.

Endothelin-1 down-regulates nuclear factor erythroid 2-related factor-2 and contributes to perivascular adipose tissue dysfunction in obesity.

Perivascular adipose tissue (PVAT) negatively regulates vascular muscle contraction. However, in the context of obesity, the PVAT releases vasoconstrictor substances that detrimentally affect vascular function. A pivotal player in this scenario is the peptide endothelin-1 (ET-1), which induces oxidative stress and disrupts vascular function. The present study postulates that obesity augments ET-1 production in the PVAT, decreases the function of the nuclear factor erythroid 2-related factor-2 (Nrf2) transcription factor, further increasing reactive oxygen species (ROS) generation, culminating in PVAT dysfunction. Male C57BL/6 mice were fed either a standard or a high-fat diet for 16 weeks. Mice were also treated with saline or a daily dose of 100 mg·kg-1 of the ETA and ETB receptor antagonist Bosentan, for 7 days. Vascular function was evaluated in thoracic aortic rings, with and without PVAT. Mechanistic studies utilized PVAT from all groups and cultured WT-1 mouse brown adipocytes. PVAT from obese mice exhibited increased ET-1 production, increased ECE1 and ETA gene expression, loss of the anticontractile effect, as well as increased ROS production, decreased Nrf2 activity, and downregulated expression of Nrf2-targeted antioxidant genes. PVAT of obese mice also exhibited increased expression of Tyr216-phosphorylated-GSK3ß and KEAP1, but not BACH1 - negative Nrf2 regulators. Bosentan treatment reversed all these effects. Similarly, ET-1 increased ROS generation and decreased Nrf2 activity in brown adipocytes, events mitigated by BQ123 (ETA receptor antagonist). These findings place ET-1 as a major contributor to PVAT dysfunction in obesity and highlight that pharmacological control of ET-1 effects restores PVAT's cardiovascular protective role.

Endothelin-1 (ET-1) contributes to senescence and phenotypic changes in brain pericytes in diabetes-mimicking conditions.

Diabetes mediates endothelial dysfunction and increases the risk of Alzheimer's disease and related dementias. Diabetes also dysregulates the ET system. ET-1-mediated constriction of brain microvascular pericytes (BMVPCs) has been shown to contribute to brain hypoperfusion. Cellular senescence, a process that arrests the proliferation of harmful cells and instigates phenotypical changes and proinflammatory responses in endothelial cells that impact their survival and function. Thus, we hypothesized that ET-1 mediates BMVPC senescence and phenotypical changes in diabetes-like conditions. Human BMVPCs were incubated in diabetes-like conditions with or without ET-1 (1 µmol/L) for 3 and 7 days. Hydrogen peroxide (100 µmol/L H2O2) was used as a positive control for senescence and to mimic ischemic conditions. Cells were stained for senescence-associated ß-galactosidase or processed for immunoblotting and quantitative real-time PCR analyses. In additional experiments, cells were stimulated with ET-1 in the presence or absence of ETA receptor antagonist BQ-123 (20 µmol/L) or ETB receptor antagonist BQ-788 (20 µmol/L). ET-1 stimulation increased ß-galactosidase accumulation which was prevented by BQ-123. ET-1 also increased traditional senescence marker p16 protein and pericyte-specific senescence markers, TGFB1i1, PP1CA, and IGFBP7. Furthermore, ET-1 stimulated contractile protein α-SMA and microglial marker ostepontin in high glucose suggesting a shift toward an ensheathing or microglia-like phenotype. In conclusion, ET-1 triggers senescence, alters ETA and ETB receptors, and causes phenotypical changes in BMVPCs under diabetes-like conditions. These in vitro findings need to be further studied in vivo to establish the role of ETA receptors in the progression of pericyte senescence and phenotypical changes in VCID.

Adipocyte endothelin B receptor activation inhibits adiponectin production and causes insulin resistance in obese mice.

AIMS: Endothelin-1 (ET-1) is elevated in patients with obesity and adipose tissue of obese mice fed high-fat diet (HFD); however, its contribution to the pathophysiology of obesity is not fully understood. Genetic loss of endothelin type B receptors (ETB) improves insulin sensitivity in rats and leads to increased circulating adiponectin, suggesting that ETB activation on adipocytes may contribute to obesity pathophysiology. We hypothesized that elevated ET-1 in obesity promotes insulin resistance by reducing the secretion of insulin sensitizing adipokines, via ETB receptor. METHODS: Male adipocyte-specific ETB receptor knockout (adETBKO), overexpression (adETBOX), or control littermates were fed either normal diet (NMD) or high-fat diet (HFD) for 8 weeks. RESULTS: RNA-sequencing of epididymal adipose (eWAT) indicated differential expression of over 5500 genes (p < 0.05) in HFD compared to NMD controls, and changes in 1077 of these genes were attenuated in HFD adETBKO mice. KEGG analysis indicated significant increase in metabolic signaling pathway. HFD adETBKO mice had significantly improved glucose and insulin tolerance compared to HFD control. In addition, adETBKO attenuated changes in plasma adiponectin, insulin, and leptin that is observed in HFD versus NMD control mice. Treatment of primary adipocytes with ET-1 caused a reduction in adiponectin production that was attenuated in cells pretreated with an ETB antagonist. CONCLUSION: These data indicate elevated ET-1 in adipose tissue of mice fed HFD inhibits adiponectin production and causes insulin resistance through activation of the ETB receptor on adipocytes.

Levels of Plasma Endothelin-1, Circulating Endothelial Cells, Endothelial Progenitor Cells, and Cytokines after Cardiopulmonary Bypass in Children with Congenital Heart Disease: Role of Endothelin-1 Regulation.

Congenital heart disease (CHD) can be complicated by pulmonary arterial hypertension (PAH). Cardiopulmonary bypass (CPB) for corrective surgery may cause endothelial dysfunction, involving endothelin-1 (ET-1), circulating endothelial cells (CECs), and endothelial progenitor cells (EPCs). These markers can gauge disease severity, but their levels in children's peripheral blood still lack consensus for prognostic value. The aim of our study was to investigate changes in ET-1, cytokines, and the absolute numbers (Ɲ) of CECs and EPCs in children 24 h before and 48 h after CPB surgery to identify high-risk patients of complications. A cohort of 56 children was included: 41 cases with CHD-PAH (22 with high pulmonary flow and 19 with low pulmonary flow) and 15 control cases. We observed that Ɲ-CECs increased in both CHD groups and that Ɲ-EPCs decreased in the immediate post-surgical period, and there was a strong negative correlation between ET-1 and CEC before surgery, along with significant changes in ET-1, IL8, IL6, and CEC levels. Our findings support the understanding of endothelial cell precursors' role in endogenous repair and contribute to knowledge about endothelial dysfunction in CHD.

Endothelin-1 increases Na+-K+-2Cl- cotransporter-1 expression in cultured astrocytes and in traumatic brain injury model: An involvement of HIF1α activation.

Na+-K+-2Cl- cotransporter-1 (NKCC1) is present in brain cells, including astrocytes. The expression of astrocytic NKCC1 increases in the acute phase of traumatic brain injury (TBI), which induces brain edema. Endothelin-1 (ET-1) is a factor that induces brain edema and regulates the expression of several pathology-related genes in astrocytes. In the present study, we investigated the effect of ET-1 on NKCC1 expression in astrocytes. ET-1 (100 nM)-treated cultured astrocytes showed increased NKCC1 mRNA and protein levels. The effect of ET-1 on NKCC1 expression in cultured astrocytes was reduced by BQ788 (1 µM), an ETB antagonist, but not by FR139317 (1 µM), an ETA antagonist. The involvement of ET-1 in NKCC1 expression in TBI was examined using a fluid percussion injury (FPI) mouse model that replicates the pathology of TBI with high reproducibility. Administration of BQ788 (15 nmol/day) decreased FPI-induced expressions of NKCC1 mRNA and protein, accompanied with a reduction of astrocytic activation. FPI-induced brain edema was attenuated by BQ788 and NKCC1 inhibitors (azosemide and bumetanide). ET-1-treated cultured astrocytes showed increased mRNA and protein expression of hypoxia-inducible factor-1α (HIF1α). Immunohistochemical observations of mouse cerebrum after FPI showed co-localization of HIF1α with GFAP-positive astrocytes. Increased HIF1α expression in the TBI model was reversed by BQ788. FM19G11 (an HIF inhibitor, 1 µM) and HIF1α siRNA suppressed ET-induced increase in NKCC1 expression in cultured astrocytes. These results indicate that ET-1 increases NKCC1 expression in astrocytes through the activation of HIF1α.

A review of novel endothelin antagonists and overview of non-steroidal mineralocorticoid antagonists for treating resistant hypertension: An update.

Several agents are emerging from five different novel classes of antihypertensive medications. We will focus on endothelin antagonists and non-steroidal mineralocorticoid receptor antagonists. While several agents exist in this later class, only a couple have demonstrated superior efficacy in resistant hypertension management. Endothelin receptor antagonists are effective therapy for primary and resistant hypertension, but they are not widely used. This is due to side effects demonstrated in large clinical trials, specifically increased peripheral edema and worsening heart failure in some cases, as well as the availability of many alternative agents to manage blood pressure effectively. However, the relationship between endothelin and its close ties to hypertension is evolving. Recent pre-clinical work explores new applications of more selective endothelin receptor antagonists. They suggest that specific subtypes of hypertension may benefit more from endothelin receptor blockade than simply those with primary hypertension. We review this topic and other related data. Lastly, we also provide a brief overview of non-steroidal mineralocorticoid receptor antagonists as some in the class show promise as antihypertensive agents.

Endothelin-1 influences mechanical properties and contractility of hiPSC derived cardiomyocytes resulting in diastolic dysfunction.

A better understanding of the underlying pathomechanisms of diastolic dysfunction is crucial for the development of targeted therapeutic options with the aim to increase the patients' quality of life. In order to shed light on the processes involved, suitable models are required. Here, effects of endothelin-1 (ET-1) treatment on cardiomyocytes derived from human induced pluripotent stem cells (hiPSCs) were investigated. While it is well established, that ET-1 treatment induces hypertrophy in cardiomyocytes, resulting changes in cell mechanics and contractile behavior with focus on relaxation have not been examined before. Cardiomyocytes were treated with 10 nM of ET-1 for 24 h and 48 h, respectively. Hypertrophy was confirmed by real-time deformability cytometry (RT-DC) which was also used to assess the mechanical properties of cardiomyocytes. For investigation of the contractile behavior, 24 h phase contrast video microscopy was applied. To get a deeper insight into changes on the molecular biological level, gene expression analysis was performed using the NanoString nCounter® cardiovascular disease panel. Besides an increased cell size, ET-1 treated cardiomyocytes are stiffer and show an impaired relaxation. Gene expression patterns in ET-1 treated hiPSC derived cardiomyocytes showed that pathways associated with cardiovascular diseases, cardiac hypertrophy and extracellular matrix were upregulated while those associated with fatty acid metabolism were downregulated. We conclude that alterations in cardiomyocytes after ET-1 treatment go far beyond hypertrophy and represent a useful model for diastolic dysfunction.

The effect of endothelin a receptor inhibition and biological sex on cutaneous microvascular function in non-Hispanic Black and White young adults.

The purpose of this study was to investigate whether endothelin-A receptor (ETAR) inhibition in non-Hispanic Black (NHB) and White (NHW) young adults depends on biological sex. We recruited females during low hormone (n = 22) and high hormone (n = 22) phases, and males (n = 22). Participants self-identified as NHB (n = 33) or NHW (n = 33). Participants were instrumented with two microdialysis fibers: (1) lactated Ringer's (control) and (2) 500 nM BQ-123 (ETAR antagonist). Local heating was used to elicit cutaneous vasodilation, and an infusion of 20 mM L-NAME to quantify NO-dependent vasodilation. At control sites, NO-dependent vasodilation was lowest in NHB males (46 ± 13 %NO) and NHB females during low hormone phases (47 ± 12 %NO) compared to all NHW groups. Inhibition of ETAR increased NO-dependent vasodilation in NHB males (66 ± 13 %NO), in both groups of females during low hormone phases (NHW, control: 64 ± 12 %NO, BQ-123: 85 ± 11 %NO; NHB, BQ-123: 68 ± 13 %NO), and in NHB females during high hormone phases (control: 61 ± 11 %NO, BQ-123: 83 ± 9 %NO). There was no effect for ETAR inhibition in NHW males or females during high hormone phases. These data suggest the effect of ETAR inhibition on NO-dependent vasodilation is influenced by biological sex and racial identity.

Characterizing the Linkage of Systemic Hypoxia and Angiogenesis in High-Grade Glioma to Define the Changes in Tumor Microenvironment for Predicting Prognosis.

High-grade gliomas (HGG) comprising WHO grades 3 and 4 have a poor overall survival (OS) that has not improved in the past decade. Herein, markers representing four components of the tumor microenvironment (TME) were identified to define their linked expression in TME and predict the prognosis in HGG, namely, interleukin6 (IL6, inflammation), inducible nitric oxide synthase(iNOS), heat shock protein-70 (HSP70, hypoxia), vascular endothelial growth receptor (VEGF), and endothelin1 (ET1) (angiogenesis) and matrix metalloprotease-14 (MMP14) and intercellular adhesion molecule1 (ICAM1, extracellular matrix). To establish a non-invasive panel of biomarkers for precise prognostication in HGG. Eighty-six therapy-naive HGG patients with 45 controls were analyzed for the defined panel. Systemic expression of extracellular/secretory biomarkers was screened dot-immune assay (DIA), quantified by ELISA, and validated by immunocytochemistry (ICC). Expression of iNOS, HSP70, IL-6, VEGF, ET1, MMP14, and ICAM1 was found to be positively associated with grade. Quantification of circulating levels of the markers by ELISA and ICC presented a similar result. The biomarkers were observed to negatively correlate with OS (p < 0.0001). Cox-regression analysis yielded all biomarkers as good prognostic indicators and independent of confounders. On applying combination statistics, the biomarker panel achieved higher sensitivity than single markers to define survival. The intra-association of all seven biomarkers was significant, hinting of a cross-talk between the TME components and a hypoxia driven systemic inflammation upregulating the expression of other components. This is a first ever experimental study of a marker panel that can distinguish between histopathological grades and also delineate differential survival using liquid biopsy, suggesting that markers of hypoxia can be a cornerstone for personalized therapy. The panel of biomarkers of iNOS, HSP70, IL-6, VEGF, ET1, MMP14, and ICAM1 holds promise for prognostication in HGG.