Endothelin Antagonists Research Articles

Vasoconstrictor antagonism improves functional and structural vascular alterations and liver damage in rats with early NAFLD

Background & AimsIntrahepatic vascular resistance is increased in early non-alcoholic fatty liver disease (NAFLD), potentially leading to tissue hypoxia and triggering disease progression. Hepatic vascular hyperreactivity to vasoconstrictors has been identified as an underlying mechanism. This study investigates vasoconstrictive agonism and antagonism in 2 models of early NAFLD and in non-alcoholic steatohepatitis (NASH).MethodsThe effects of endothelin-1 (ET-1), angiotensin II (ATII) and thromboxane A2 (TxA2) agonism and antagonism were studied by in situ ex vivo liver perfusion and preventive/therapeutic treatment experiments in a methionine-choline-deficient diet model of steatosis. Furthermore, important results were validated in Zucker fatty rats after 4 or 8 weeks of high-fat high-fructose diet feeding. In vivo systemic and portal pressures, ex vivo transhepatic pressure gradients (THPG) and transaminase levels were measured. Liver tissue was harvested for structural and mRNA analysis.ResultsThe THPG and consequent portal pressure were significantly increased in both models of steatosis and in NASH. ET-1, ATII and TxA2 increased the THPG even further. Bosentan (ET-1 receptor antagonist), valsartan (ATII receptor blocker) and celecoxib (COX-2 inhibitor) attenuated or even normalised the increased THPG in steatosis. Simultaneously, bosentan and valsartan treatment improved transaminase levels. Moreover, bosentan was able to mitigate the degree of steatosis and restored the disrupted microvascular structure. Finally, beneficial vascular effects of bosentan endured in NASH.ConclusionsAntagonism of vasoconstrictive mediators improves intrahepatic vascular function. Both ET-1 and ATII antagonists showed additional benefit and bosentan even mitigated steatosis and structural liver damage. In conclusion, vasoconstrictive antagonism is a potentially promising therapeutic option for the treatment of early NAFLD.Lay summaryIn non-alcoholic fatty liver disease (NAFLD), hepatic blood flow is impaired and the blood pressure in the liver blood vessels is increased as a result of an increased response of the liver vasculature to vasoconstrictors. Using drugs to block the constriction of the intrahepatic vasculature, the resistance of the liver blood vessels decreases and the increased portal pressure is reduced. Moreover, blocking the vasoconstrictive endothelin-1 pathway restored parenchymal architecture and reduced disease severity.

THE ROLE OF PROVOCATIVE TESTING DURING HEMODYNAMIC ASSESSMENT TO IMPROVE PULMONARY HYPERTENSION DIAGNOSIS IN OLDER ADULTS

BACKGROUND Pulmonary Hypertension (PH) complicates cardiac and respiratory diseases. Hemodynamic classification of PH broadly defines 2 subsets: pulmonary arterial hypertension (PAH) and PH of left heart disease (PH-LHD). In older patients, particularly with cardiovascular risk factors, clinical and hemodynamic characteristics of PAH and PH-LHD overlap. Thus clinicians face a therapeutic dilemma; PAH therapy may be underutilized in PAH patients to avoid inadvertent administration to PH-LHD patients. Our goal was to evaluate the utility of right heart catheterization(RHC) with exercise to support clinical decisions regarding use of PAH therapy in older adults suspected of having PH with risk factors for PH-LHD. METHODS AND RESULTS Retrospective cohort study of patients referred by a PH program for RHC with exercise to evaluate suspected or confirmed PH, between 2017-2020. Consecutive patients >50 years and at least 1 cardiovascular risk factor (BMI>30kg/m2, HTN, diabetes, hypercholesterolemia, ischemic heart disease, atrial fibrillation(AF)) were included. Primary outcome: use of PAH therapy at the time of RHC and in follow-up. Secondary outcomes: patient reported quality of life (QOL) at time of RHC and in follow-up, using SF36 assay. 61 patients were included in our study, mean age:69±10 years, 56% women. Over 90% patients has 2 or more risk factors for PH-LHD, 34% had a history of AF. At time of RHC, although more than 30% were known to have PH, PAH therapy was prescribed to 20% of patients; phosphodiesterase type 5 inhibitors (PDE5i) n=9, endothelin antagonists (ETA) n=1, and dual therapy (PDE5i+ETA) n=1. Baseline RHC demonstrated no PH in 22 patients (36%) and PH in 39 (64%): 27 with PAH, and 12 with PH-LHD. After exercise RHC, 14 (23%) had no PH, 44 were diagnosed with PH:16 with PAH and 28 with PH-LHD. In follow-up, the proportion of cohort treated with PAH therapy increased to 28%, mostly patients confirmed to have PAH at rest and exercise. PAH therapy included single PDE5i (8 patients), single ETA (5 patients), or combination therapy (with 2 or more PAH medications, 4 patients). Improvement in the physical functioning (median 10, IQR 23.8) and overall health (median 25, IQR 43.8) aspects of QOL were seen at 1 year follow-up. CONCLUSION Among patients with suspected or confirmed PH, and high burden of cardiovascular risk factors, use of PAH therapies is low. Exercise RHC increased the proportion of patients diagnosed with PH and shifted the classification in a proportion from PAH to PH-LHD. QOL improved as well. Pulmonary Hypertension (PH) complicates cardiac and respiratory diseases. Hemodynamic classification of PH broadly defines 2 subsets: pulmonary arterial hypertension (PAH) and PH of left heart disease (PH-LHD). In older patients, particularly with cardiovascular risk factors, clinical and hemodynamic characteristics of PAH and PH-LHD overlap. Thus clinicians face a therapeutic dilemma; PAH therapy may be underutilized in PAH patients to avoid inadvertent administration to PH-LHD patients. Our goal was to evaluate the utility of right heart catheterization(RHC) with exercise to support clinical decisions regarding use of PAH therapy in older adults suspected of having PH with risk factors for PH-LHD. Retrospective cohort study of patients referred by a PH program for RHC with exercise to evaluate suspected or confirmed PH, between 2017-2020. Consecutive patients >50 years and at least 1 cardiovascular risk factor (BMI>30kg/m2, HTN, diabetes, hypercholesterolemia, ischemic heart disease, atrial fibrillation(AF)) were included. Primary outcome: use of PAH therapy at the time of RHC and in follow-up. Secondary outcomes: patient reported quality of life (QOL) at time of RHC and in follow-up, using SF36 assay. 61 patients were included in our study, mean age:69±10 years, 56% women. Over 90% patients has 2 or more risk factors for PH-LHD, 34% had a history of AF. At time of RHC, although more than 30% were known to have PH, PAH therapy was prescribed to 20% of patients; phosphodiesterase type 5 inhibitors (PDE5i) n=9, endothelin antagonists (ETA) n=1, and dual therapy (PDE5i+ETA) n=1. Baseline RHC demonstrated no PH in 22 patients (36%) and PH in 39 (64%): 27 with PAH, and 12 with PH-LHD. After exercise RHC, 14 (23%) had no PH, 44 were diagnosed with PH:16 with PAH and 28 with PH-LHD. In follow-up, the proportion of cohort treated with PAH therapy increased to 28%, mostly patients confirmed to have PAH at rest and exercise. PAH therapy included single PDE5i (8 patients), single ETA (5 patients), or combination therapy (with 2 or more PAH medications, 4 patients). Improvement in the physical functioning (median 10, IQR 23.8) and overall health (median 25, IQR 43.8) aspects of QOL were seen at 1 year follow-up. Among patients with suspected or confirmed PH, and high burden of cardiovascular risk factors, use of PAH therapies is low. Exercise RHC increased the proportion of patients diagnosed with PH and shifted the classification in a proportion from PAH to PH-LHD. QOL improved as well.

Endothelin-1 and Parameters of Systolic Blood Pressure in Hemodialysis.

Hypertension is common in hemodialysis (HD) patients. Increased blood pressure (BP) variability, particularly higher and lower extremes, is associated with adverse outcomes. We explored the association of endothelin-1 (ET-1), a potent vasoconstrictor, with different BP parameters (pre-HD, intra-HD, and post-HD) during HD in a contemporary patient cohort. This study uses the DaVita Biorepository, a longitudinal prospective cohort study with quarterly collection of clinical data and biospecimens. Unadjusted and adjusted linear mixed effects regression models were fit to determine association of pre-HD ET-1 (log-transformed and quartiles) with HD-related systolic BP (SBP) parameters (pre-HD, nadir intra-HD, and post-HD). As ET-1 was measured at baseline, analyses were restricted to 1 year of follow-up. Among 769 participants, mean age was 52 years, 42% were females, and 41% were Black. Mean pre-HD SBP was 152 (±28) mm Hg and mean ET-1 concentration was 2.3 (±1.2) ng/ml. In fully adjusted models, each unit increase in SD of log-transformed ET-1 was associated with a 2.7 (95% confidence interval [CI] 1.5, 4.0) mm Hg higher pre-SBP; 1.6 (95% CI 0.9, 2.3) mm Hg higher nadir SBP; and 2.0 (95% CI 1.1, 2.9) mm Hg higher post-SBP. Each SD increase in log-transformed ET-1 was associated with 21% higher odds of experiencing intradialytic hypertension (odds ratio 1.21; 95% CI 1.10-1.34). Higher baseline ET-1 levels are independently associated with higher SBP and higher odds of intradialytic hypertension. These results highlight a potential role for ET-1 in BP control in HD patients and raise the possibility of ET-1 antagonism as a therapeutic target.

MO230A PHASE 3, RANDOMIZED, DOUBLE-BLIND, PLACEBO CONTROLLED STUDY OF ATRASENTAN IN PATIENTS WITH IGA NEPHROPATHY (THE ALIGN STUDY)

Abstract Background and Aims IgA nephropathy (IgAN) is the most common primary glomerulonephritis globally and an important cause of chronic kidney disease (CKD). Up to 40% of IgAN patients are at risk of progressing to end-stage kidney disease (ESKD) and proteinuria is the strongest predictor of progression. There are no approved therapies for IgAN, leaving an important need for new strategies to lower proteinuria and preserve kidney function in high-risk patients. Endothelin A (ETA) receptor activation drives proteinuria, along with kidney inflammation and fibrosis. Atrasentan, a potent and selective ETA antagonist, has been studied extensively in >5,000 patients with type 2 diabetes and kidney disease (DKD), demonstrating clinically significant and sustained reductions in proteinuria when administered on top of a maximum tolerated dose of RAS inhibitor (RASi). In a global Phase 3 outcome study in DKD (SONAR), atrasentan demonstrated a 35% reduced risk of the primary composite outcome of doubling of serum creatinine or end stage kidney disease (95% CI: 0.49, 0.88; P = 0.005). The most common adverse event was fluid retention. Selective ETA blockade represents a promising approach to reduce proteinuria and preserve kidney function in high risk IgAN patients. This is a presentation of a global, phase 3, double-blind, placebo-controlled trial to determine the effect of atrasentan in IgAN patients at high risk of kidney function loss. Method Approximately 320 patients across North America, South America, Europe, and Asia-Pacific with biopsy-proven IgAN will be randomized to receive 0.75 mg atrasentan or placebo daily for 132 weeks. Patients will continue receiving a maximally tolerated and stable dose of a RAS inhibitor as standard of care. The study will also include patients that are unable to tolerate RAS inhibitor therapy. Additional eligibility criteria include urine protein creatinine ratio (UPCR) ≥1 g/g and eGFR ≥30 mL/min/1.73 m2. Participants will have study assessments over two and a half years with options for remote study visits using telemedicine and home health visits. The primary objective is to evaluate the effect of atrasentan versus placebo on proteinuria at Week 24. Secondary objectives include evaluating the change from baseline in eGFR, safety, and tolerability, and quality of life. Results N/A Conclusion N/A

POS-380 A PHASE 3, RANDOMIZED, DOUBLE-BLIND, PLACEBO-CONTROLLED STUDY OF ATRASENTAN IN PATIENTS WITH IGA NEPHROPATHY (THE ALIGN STUDY)

IgA nephropathy (IgAN) is the most common primary glomerulonephritis globally and an important cause of chronic kidney disease (CKD). Up to 40% of IgAN patients are at risk of progressing to end-stage kidney disease (ESKD) and proteinuria is the strongest predictor of progression. There are no approved therapies for IgAN, leaving an important need for new strategies to lower proteinuria and preserve kidney function in high risk patients. Endothelin A (ETA) receptor activation drives proteinuria, along with kidney inflammation and fibrosis. Atrasentan, a potent and selective ETA antagonist, has been studied extensively in >5,000 patients with type 2 diabetes and kidney disease (DKD), demonstrating clinically significant and sustained reductions in proteinuria when administered on top of a maximum tolerated dose of RAS inhibitor (RASi). In a global Phase 3 outcome study in DKD (SONAR), atrasentan demonstrated a 35% reduced risk of the primary composite outcome of doubling of serum creatinine or end stage kidney disease (95% CI: 0.49, 0.88; P = 0.005). The most common adverse event was fluid retention. Selective ETA blockade represents a promising approach to reduce proteinuria and preserve kidney function in high risk IgAN patients. A global, phase 3, double-blind, placebo-controlled study is planned to determine the effect of atrasentan in IgAN patients at high risk of kidney function loss. Approximately 320 patients across North America, South America, Europe, and Asia-Pacific with biopsy-proven IgAN will be randomized to receive 0.75 mg atrasentan or placebo daily for 132 weeks. Patients will continue receiving a maximally tolerated and stable dose of a RAS inhibitor as standard of care. The study will also include a cohort of patients that are unable to tolerate RAS inhibitor therapy. Additional eligibility criteria include urine protein creatinine ratio (UPCR) ≥1 g/g and eGFR ≥30 mL/min/1.73 m2. Participants will have study assessments over two and a half years with options for remote study visits using telemedicine and home health visits. The primary objective is to evaluate the effect of atrasentan versus placebo on proteinuria at Week 24. Secondary objectives include evaluating the change in eGFR over time, safety, and tolerability, as well as quality of life. The ALIGN Study will begin recruiting patients in early 2021.

Development of industrial efficient asymmetric synthesis of endothelin-A antagonist ABT-546: A case study based on green chemistry perspective

The catalytic, extremely effective enantioselective conjugate-addition strategy was approved by via 4 mol% of bis(oxazoline)-Mg(OTf)2 along with amine complex as co-catalyst. The magnicium triflate based catalysis afford 88% selectivity in the molecule and provide less dependence on the tartrate salt for enantioselectivity, which was previously prepared for attaining chiral purity for the synthesis of the endothelin-A antagonist ABT-546. Along with enantioselective conjugate-addition the new strategy involves green solvents in the final steps of ABT-546 drug preparation. The use of green solvent owes its own advantage of minimizing the residues remaining in the API synthesized. The article includes the case study of the ABT-546 to discuss the green chemistry objectives fulfilled by pharma industry.

Effects of Selective Endothelin Receptor Antagonist on Vegf Signaling System in Diabetic Penis: A Possible Clinical Implication for Diabetes Induced Erectile Dysfunction

Erectile dysfunction (ED) affects around 50 percent of male diabetic patients due to vascular and neuropathic complications arising from diabetes. Vascular endothelial growth factor (VEGF) has been extensively investigated for its pathogenic relevance in various diabetes complications, and we have already noted that VEGF signaling is significantly reduced at the insulin-resistant stage in the penis of type II diabetic rat model. The present research used a three-week streptozotocin (STZ)-induced diabetic (DM) rat model to determine the expression of VEGF with NO mechanism in penile tissue and subsequently investigated its impact endothelin antagonism on these shifts. Citrate saline vehicle or STZ (65 mg/kg IP) was administered to male Sprague-Dawley rats (weight 453 ± 23 g). Hyperglycemia confirmed diabetes, and then after 1 week of diabetes, animals were divided into receiving endothelin-A (ET-A) receptor antagonists (TA-0201, 1 mg/kg) or saline by osmotic minipump for 2 weeks and then sacrificed. Significantly improved glucose levels in DM rats (405 ± 103 mg/dL) relative to non-DM rats (120 ± 8 mg/dL) and higher local ET-1 levels in DM penis by 20% are observed. A 30 percent decline in penile tissue expression of VEGF was observed in DM rats and improved by an antagonist with ET. Penile NO and eNOS levels in DM rats decreased, while ET-A receptor antagonist significantly increased. Therefore, we infer that ET antagonism seemed able to restore the down-regulated VEGF and was possibly efficient in restoring the decreased levels of NO and eNOS in DM.

Endothelin-1 and peak oxygen consumption in patients with heart failure with preserved ejection fraction

BackgroundMechanisms of exercise intolerance in patients with heart failure with preserved ejection fraction (HFpEF) are not well understood. Pulmonary hypertension, a common accompaniment in patients with HFpEF, is associated with poor outcomes. While Endothelin -1 (ET-1) plays a mechanistic role in pulmonary hypertension, its role in exercise intolerance in HFpEF is not well established. ObjectiveTo explore the association between plasma ET-1 levels and maximal oxygen consumption (pVO2), and their changes over 24 weeks in HFpEF. MethodsThis is a post-hoc analysis of the Phosphodiesterase-5 Inhibition to Improve Clinical Status and Exercise Capacity in Heart Failure with Preserved Ejection Fraction (RELAX) trial. We performed linear regressions to assess the relationship between plasma ET-1 and pVO2. We also used linear regressions to determine whether ET-1 was associated with change in peak VO2 (ΔpVO2). ResultsA total of 210 patients were included. Baseline plasma ET-1 levels were associated with older age, higher NT-proBNP levels, higher serum creatinine levels, and higher prevalence of atrial fibrillation. Patients with higher ET1 levels also had higher plasma galectin-3 and CITP levels. After multiple adjustments, baseline ET1 levels were associated with lower pVO2 (β -0.927, SE 0.196, p < 0.001). Over 24 weeks, the change in ET1 levels was associated with the change in pVO2 (multivariable adjusted β -0.415, SE 0.115, p = 0.018). Baseline ET1 levels did not modify the effect of sildenafil on change in peak VO2. ConclusionsPlasma ET1 levels are significantly associated with lower exercise oxygen consumption both at baseline and longitudinally over 24 weeks. Future studies should explore Endothelin-1 antagonism to improve exercise tolerance in HFpEF.

Resistance training increases insulin-induced vasodilation in the mesenteric artery of healthy rats.

This study evaluated the ability of resistance training (RT) of moderate intensity to promote vascular changes in insulin-induced vasodilation in healthy animals. Wistar rats were divided into two groups: control (CON) and trained (eight weeks of training, performing 3 sets with 10 repetitions at 60% of maximum intensity). Forty-eight hours after the last session of the RT, the animals were sacrificed and vascular reactivity to insulin in the absence and presence of LY294002 (phosphatidylinositol 3-kinase inhibitors (PI3K), L-NAME (nitric oxide synthase (NOS) inhibitors) and BQ123 (endothelin A antagonist (ET-A) receptor). In addition, phenylephrine (Phe)-induced vasoconstriction in the absence and presence of L-NAME was also evaluated. The RT group showed greater vasodilation in maximal response compared to the CON group. After PI3K inhibition, vasodilation was reduced in both groups. However, when the NOS participation was evaluated, the RT group showed contraction in relation to the CON group, which was abolished by BQ123. In addition, the RT group had an increase in nitrite levels compared to the CON group. When the Phe response was evaluated, there was a reduction in tension in the RT group compared to the CON group. The results suggest that RT improves vascular reactivity.

Hipertensión pulmonar. De las moléculas vasomotoras al tratamiento

Pulmonary Hypertension is characterized by the increase of the pulmonary systolic pressure above 30 mm Hg or 25 of mean pressure. Different diseases generate changes in the physiology of the vessel wall. The balance between vasoconstrictor and vasodilator molecules, mainly released by the endothelium, is lost in favor of vasoconstrictors, which in addition to generating an inadequate vasoconstrictor response, induce proliferative changes of different cell lines that modify the structure of the vessel wall, from the hypertrophy of the media until progressive occlusion of the arteriolar beds, formation of angiomatous lesions, micro aneurysms, plexiform lesions, thrombotic occlusions and necrotizing arteritis corresponding to the different degrees of pulmonary hypertension. The symptoms of right ventricular failure, the radiographic and electrocardiographic data of right ventricular growth or dilatation, allow us to suspect the diagnosis that can be confirmed by echocardiography, measuring the peak velocity of the tricuspid regurgitation that corresponds to the systolic pressure of the pulmonary artery. The progressive severity of the lesions allows the treatment to be staggered, including measures to compensate for heart failure with loop diuretics, permanent anticoagulation, and vasodilators such as Calcium Channel Blockers and to greater severity, endothelin antagonists, phosphodiesterase 5 inhibitors, prostacyclin and derivatives and combinations of several of these drugs. The creation of a right to left shunt decompresses the lung bed, reducing pressure, with desaturation and an increase in systemic output, but improving exercise tolerance and survival.

A RARE CASE OF PORTOPULMONARY HYPERTENSION AS A COMPLICATION OF CRYPTOGENIC CIRRHOSIS

SESSION TITLE: Medical Student/Resident Pulmonary Vascular Disease Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Portopulmonary hypertension (PoPH) is a rare and serious complication of liver cirrhosis. The prevalence of PoPH is about 0.25–4% among patients with cirrhosis. Untreated PoPH can have a poor prognosis. We report a rare case of PoPH. CASE PRESENTATION: A 35 year old female with a history of cryptogenic liver cirrhosis with portal hypertension and transjugular intrahepatic portosystemic shunt (TIPS) presented to the emergency room with complaints of dyspnea, orthopnea, and dizziness which started 2 days after her 5th caesarean section. Her exercise tolerance was reduced to one block. The patient had an elevated ProBNP of 1100. Computed tomographic pulmonary angiography was negative for pulmonary embolism. Transthoracic echocardiogram showed right ventricular systolic pressure elevated at >60mm Hg, consistent with severe pulmonary hypertension (PAH) with severely dilated right atrium. The patient was transferred to a tertiary care hospital for confirmation of the diagnosis of PoPH. The patient underwent Right Heart Catheterization which confirmed severe PAH with elevated mean pulmonary artery pressure (mPAP) of 60mmhg, normal pulmonary capillary wedge pressure of 12mmhg, elevated pulmonary vascular resistance of 17 wood units. The hepatic vein wedge pressure was 23mmHg and hepatic vein pressure was 20mmHg.The hepatic venous pressure gradient (HVPG) was 3mmhg which was normal and was consistent with the fact that the patient already underwent TIPS due to underlying portal hypertension. The patient met the diagnostic criteria for PoPH. The patient was started on treprostinil infusion for pulmonary vasodilatation. The patient improved symptomatically and was eventually discharged. In her follow up pulmonary clinic appointment her exercise tolerance improved to 10 blocks with complete resolution of orthopnea. DISCUSSION: The development of PAH in patients with cirrhosis can be explained by shunting of vasoactive mediators from splanchnic to pulmonary circulation through portosystemic shunts causing vasoconstriction of the pulmonary vasculature. The acute volume loading with mobilization of plasma volume in the immediate postpartum period may have tipped the patient into acute on chronic right ventricular failure and thereby revealed her symptomatic PAH. The prompt recognition of PoPH and initiation of appropriate medical treatment ensured the recovery of the patient. CONCLUSIONS: The diagnosis of PoPH is crucial before liver transplantation as there is a high risk of death following liver transplantation if the mPAP is more than 35 mmHg. Medical treatment is essential to lower the mPAP to less than 35mmhg before proceeding for liver transplantation. Liver transplantation can be planned after successful medical treatment of PoPH with pulmonary arterial vasomodulators like prostanoids, phosphodiesterase inhibitors, and endothelin antagonists. Reference #1: Benjaminov FS, Prentice M, Sniderman KW, et al. Portopulmonary hypertension in decompensated cirrhosis with refractory ascites. Gut 2003; 52: 1355-1362. Reference #2: Saleemi S. Portopulmonary hypertension.Ann Thorac Med. 2010 Jan-Mar; 5(1): 5–9. Reference #3: Porres-Aguilar M, Zuckerman MJ, Figueroa-Casas JB, et al.Portopulmonaryhypertension: state of the art. Ann Hepatol 2008; 7:321-330 DISCLOSURES: No relevant relationships by Antony Arumairaj, source=Web Response No relevant relationships by Diana Cativo, source=Web Response No relevant relationships by Imnett Habtes, source=Web Response

The incidence rate of pulmonary arterial hypertension and scleroderma renal crisis in systemic sclerosis patients with digital ulcers on endothelin antagonist receptors (ERAs) and phosphodiesterase-5 inhibitors (PDE5i).

Endothelin antagonist receptors (ERAs) and phosphodiesterase-5 inhibitors (PDE5i) are beneficial in pulmonary arterial hypertension (PAH) and digital ulcers (DU) and prevent from DU recurrences. Our study aimed to determine the difference in the incidence rate of PAH and scleroderma renal crisis (SRC) in patients with SSc and DU (SSc-DU) under ERAs/PDE5i or without treatment. We conducted a retrospective cohort study including SSc-DU patients from the Spanish Scleroderma Registry (RESCLE). The primary outcome was the incidence rate of PAH and SRC in patients under ERAs/PDE5i or not. Some 544 patients out of 1817 (29.9%) in the RESCLE database had DU, 221 (40.6%) under ERAs/PDE5i and 323 (59.4%) not. The incidence rate (95% CI) difference between patients under treatment or not under did not reach statistical significance in PAH [-0.1 (-4.8, 4.69), P = 0.988] or in SRC [0.7 (-2.2, 3.7), P = 0.620]. However, the time from the first DU to the diagnosis of SRC was delayed in treated patients [mean (s.d.) 7.6 (5.8) years vs 2.9 (5.3); P = 0.021]. The dcSSc subset was more prevalent in the treatment group (36 vs 26%; P = 0.018), along with anti-topoisomerase I antibodies (34 vs 18%; P < 0.001) and tendon friction rubs (12 vs 6%; P = 0.038), whereas the lcSSc subset was more prevalent in the no-treatment group (57 vs 66%; P = 0.031) along with ACA (37 vs 46%; P = 0.031). There was no difference in the incidence rate of PAH and SRC between groups. However, treatment with ERAs and/or PDE5i appeared to delay the occurrence of SRC.

The Role of Cerebral Hypoperfusion in Multiple Sclerosis (ROCHIMS) Trial in Multiple Sclerosis: Insights From Negative Results.

Background: Accumulating evidence indicates that mitochondrial energy failure is involved in the progressive axonal degeneration in multiple sclerosis (MS). In patients with MS, it has been shown that both levels of N-acetylaspartate (NAA), which is a marker of axonal mitochondrial energy, and cerebral blood flow (CBF) are reduced in cerebral normal appearing white matter (NAWM). The latter is likely due to the vasoconstrictive action of endothelin-1 (ET-1) produced by reactive astrocytes, which is triggered by local proinflammatory cytokines. A preliminary study in patients with MS showed that CBF could be restored to normal values after a single dose of 62.5 mg of the ET-1 antagonist bosentan.Objective: To investigate whether restoring CBF in patients with relapsing remitting MS (RRMS) increases levels of NAA in cerebral NAWM and improves clinical symptoms.Methods: 27 RRMS patients were included in a 4 weeks proof-of-concept, randomized, double-blind placebo-controlled trial (ROCHIMS) to investigate whether bosentan 62.5 mg twice daily could increase the NAA/creatine (NAA/Cr) ratio in NAWM of the centrum semiovale. Magnetic resonance imaging (MRI) assessing CBF and NAA/Cr, and clinical evaluations were performed at baseline and at end of study. Separately from the clinical trial, 10 healthy controls underwent the same baseline multimodal brain MRI protocol as the MS patients.Results: Eleven patients in the bosentan arm and thirteen patients in the placebo arm completed the study. Bosentan did not increase CBF. However, we found that CBF in the patients was not different from that of the healthy controls. There were no effects on NAA levels and clinical symptoms.Conclusions: Our study showed that CBF in RRMS patients is not always decreased and that bosentan has no effect when CBF values are within the normal range. We hypothesize that in our patients there was no significant astrocytic production of ET-1 because they had a mild disease course, with minimal local inflammatory activity. Future studies with bosentan in MS should focus on patients with elevated ET-1 levels in cerebrospinal fluid or blood.

Increased Levels of Endothelin-1 in Cerebrospinal Fluid Are a Marker of Poor Visual Recovery after Optic Neuritis in Multiple Sclerosis Patients.

Background Multiple sclerosis (MS), a chronic inflammatory and degenerative disease of the central nervous system, typically features immune-mediated focal demyelination and secondary axonal degeneration. Cerebral hypoperfusion of the normal-appearing white matter (NAWM) has been reported in MS patients and may be mediated by elevated levels of endothelin-1 (ET-1), a most potent vasoconstrictive peptide released from reactive astrocytes in MS focal lesions. Optic neuritis (ON) is one of the most frequent manifestations of MS and also shows peripapillary vascular hypoperfusion in combination with disc swelling. Aims We aimed to compare serum and cerebrospinal fluid (CSF) levels of ET-1 as a potential prognostic marker of MS-ON in two groups of patients differing for severity of MS-ON clinical presentation. Materials and Methods A cross-sectional study to compare serum and CSF levels of ET-1 between patients with clinically aggressive MS-ON (A-MS-ON) and nonaggressive MS-ON (NA-MS-ON) according to conventional ophthalmological criteria, including optical coherence tomography. CSF and serum concentrations of ET-1 were measured using a commercially available ELISA method. Results Sixteen patients consecutively referred to the Units of Neurology for visual disturbances attributable to MS were recruited, 11 (69%) patients with A-MS-ON and 5 (31%) with NA-MS-ON. Median CSF ET-1 levels and CSF/serum ET-1 quotient were significantly higher in patients with A-MS-ON (0.30 vs. 0.56 ng/ml) as compared to NA-MS-ON (0.16 vs. 0.16). Conclusions Severity and failure in the recovery from ON in MS patients may depend from vascular hypoperfusion of the optic nerve induced by high intrathecally produced ET-1, a potential prognostic marker of ON recovery in MS. The detection of CSF ET-1 levels may allow identifying groups of ON patients potentially benefitting from treatment with ET-1 antagonists (e.g., bosentan).

Endothelin-1 as a therapeutic target in autosomal dominant polycystic kidney disease .

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 ETA and ETB 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. 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. 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. 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. .

Implication of endothelin-1 in human aortic valve calcification

Aortic Stenosis (AS) is the most common acquired valvulopathy in the Western world. AS is characterized by the differenciation of valvular interstitial cells (VICs) into osteoblastic cells, leading to valvular calcification. The physiopathology of AS is not fully understood and there is, to date, no treatments to stop or slow the progression of AS. The purpose of our study was to investigate the role of endothelin-1 (ET-1) on VICs calcification. Primary human valvular interstitial cells (hVICs) were first cultured in pro-osteogenic medium or incubated with ET-1. hVICs were also co-cultured with human valvular endothelial cells (hVECs) obtained from patients with (pathological) or without (healthy) AS in Transwell™ inserts. hVICs calcification was quantified using o-cresolphthalein assay. Real-time quantitative PCR (qRT-PCR) and Western blot analysis were performed to determine the expression of ET-1 (EDN1), inflammation (IL1B, IL6) and bone markers (RUNX2, OPG, OPN). Immunochemistry was performed using ACTA2 antibody to evaluate the phenotype of VICs. hVICs showed an increase of calcification and a decrease of ACTA2 when cultured in pro-osteogenic medium or co-cultured with pathological hVECs. qRT-PCR revealed higher mRNA levels of EDN1, RUNX2, OPG, OPN, IL1B and IL6. At the same time, fibroblast marker ACTA2 was decreased. VIC fibroblastic phenotype was restored and calcification decreased when hVICs were co-cultured with healthy hVECs or incubated with ET-1 antagonist. The present study suggests that ET-1 play a role in the pathogenesis of AS, and therefore, pharmacological ET-1 antagonists could be used to attenuate or stop VIC calcification.

Response: Endothelin Antagonism and Insulin's Vascular Effects

Response: Endothelin Antagonism and Insulin's Vascular Effects

The protective effect of endothelin receptor antagonists against surgically induced impairment of gastrointestinal motility in rats.

Endothelin (ET) receptor antagonists: BQ-123 (ETA), BQ-788 (ETB), tezosentan (dual ET receptor antagonist) protect against the development of postoperative ileus (POI) evoked by ischemia-reperfusion (I/R). The current experiments explored whether ET antagonists prevent the occurrence of POI evoked by surgical gut manipulation. Intestinal transit was assessed by measuring the rate of dye migration subsequent to skin incision (SI), laparotomy (L), or laparotomy and surgical gut handling (L+M) in diethyl ether anaesthesized rats (E). Experimental animals were randomly sub-divided into two groups depending on the time of recovery following surgery: viz. either 2 or 24 h (early or late phase POI). E and SI did not affect the gastrointestinal (GI) transit. In contrast, L and L+M significantly reduced GI motility in comparison to untreated group (UN). Tezosentan (10 mg/kg), BQ-123 and BQ-788 (1 mg/kg) protected against development of L+M evoked inhibition of intestinal motility in the course of late phase, but not early phase POI. Furthermore, tezosentan alleviated the decrease in the contractile response of the longitudinal jejunal smooth muscle strips to carbachol in vitro induced by L+M. The serum ET(1–21) concentration was not increased in either the early or the late phase POI groups after surgery compared to control animals. This study indicates that delay in the intestinal transit in late phase of surgically induced POI involves an ET-dependent mechanism.

Endothelin-1 triggers human peritoneal mesothelial cells' proliferation via ERK1/2-Ets-1 signaling pathway and contributes to endothelial cell angiogenesis.

Dysfunction of the peritoneum as a dialysis organ may result from progressive membrane injury on peritoneal dialysis (PD). It has been increasingly recognized that the human peritoneal mesothelial cells (HPMCs) play a key role in peritoneal membrane early injury. Recently, it has been reported that bioincompatible PD fluid with high concentrations of glucose and glucose degradation products, low pH, high osmolality, and peritonitis stimulates HPMCs to release endothelin-1 (ET-1). ET-1 causes increased the release of vascular endothelial growth factor, which is important for tumor cell angiogenesis. We hypothesized that activating ET-1 might predict injury of peritoneal membrane. HPMCs were isolated from normal omentum. ERK1/2 and Ets-1 phosphorylation were measured by Western blot analysis. HPMC proliferation was detected by the bromodeoxyuridine (BrdU) assay. Capillary networks of tubes formed were photographed under a microscope, and five randomly selected fields from each well were analyzed for total capillary length by using Image J software. MEK-1 blocker significantly abolished the ERK1/2 activation by ET-1, which also triggered phosphorylation, thus activating the transcription factor Ets-1 downstream from ERK1/2. ET-1 was capable to induce HPMC proliferation, which could be attenuated by ET-1 antagonists. Antibody and small interfering RNA mediated blockade of Ets-1 had similar antiproliferative effects. Thus, ET-1 specifically triggered HPMC proliferation via ERK1/2-Ets-1 signaling pathway. VEGF production and endothelial cell angiogenesis were significantly in response to conditioned medium from HPMCs treated with ET-1. ET-1 triggered HPMC proliferation through the ERK1/2-Ets-1 signaling pathway and contributed to VEGF production and endothelial cell angiogenesis.

Endothelins in inflammatory neurological diseases.

Endothelins were discovered more than thirty years ago as potent vasoactive compounds. Beyond their well-documented cardiovascular properties, however, the contributions of the endothelin pathway have been demonstrated in several neuroinflammatory processes and the peptides have been reported as clinically relevant biomarkers in neurodegenerative diseases. Several studies report that endothelin-1 significantly contributes to the progression of neuroinflammatory processes, particularly during infections in the central nervous system (CNS), and is associated with a loss of endothelial integrity at the blood brain barrier level. Because of the paucity of clinical trials with endothelin-1 antagonists in several infectious and non-infectious neuroinflammatory diseases, it remains an open question whether the 21 amino acid peptide is a mediator/modulator rather than a biomarker of the progression of neurodegeneration. This review focuses on the potential roles of endothelins in the pathology of neuroinflammatory processes, including infectious diseases of viral, bacterial or parasitic origin in which the synthesis of endothelins or its pharmacology have been investigated from the cell to the bedside in several cases, as well as in non-infectious inflammatory processes such as neurodegenerative disorders like Alzheimers Disease or central nervous system vasculitis.