Endothelin System Research Articles

Effects of systemic and renal intramedullary endothelin-1 receptor blockade on tissue NO and intrarenal hemodynamics in normotensive and hypertensive rats

Endothelin 1 (ET-1) seems essential in salt-dependent hypertension, and activation of ETA receptors causes renal vasoconstriction. However, the response in the renal medulla and the role of tissue NO availability has never been adequately explored in vivo. We examined effects of ETA and ETB receptor blockade (atrasentan and BQ788) on blood pressure (MAP), medullary blood flow (MBF) and medullary tissue NO. Effects of systemic and intramedullary blocker application were compared in anesthetized normotensive ET-1-pretreated Sprague-Dawley rats (S-D), in salt-dependent hypertension (HS/UNX) and in spontaneously hypertensive rats (SHR). Total renal blood flow (RBF) was measured using a Transonic renal artery probe, MBF as laser-Doppler flux, and tissue NO signal using selective electrodes.In normotensive rats ET-1 significantly increased MAP, decreased RBF (−20%) and renal medullary NO. In HS/UNX rats atrasentan decreased MAP and increased medullary NO, earlier and more profoundly with intravenous infusion. In SHR atrasentan decreased MAP, more effectively with intravenous infusion; the increase in tissue NO (∼10%) was similar with both routes; however, only intramedullary atrasentan increased MBF. No consistent responses to BQ788 were seen.We confirmed dominant role of ETA receptors in regulation of blood pressure and renal hemodynamics in normotensive and hypertensive rats and provided novel evidence for the role of ETA in control of intrarenal NO bioavailability in salt-dependent and spontaneous hypertension. Under conditions of activation of the endothelin system ETB stimulation preserved medullary perfusion.

ET-1 as a Sex-Specific Mechanism Impacting Age-Related Changes in Vascular Function.

Aging is a primary risk factor for cardiovascular disease (CVD), which is the leading cause of death in developed countries. Globally, the population of adults over the age of 60 is expected to double by the year 2050. CVD prevalence and mortality rates differ between men and women as they age in part due to sex-specific mechanisms impacting the biological processes of aging. Measures of vascular function offer key insights into cardiovascular health. Changes in vascular function precede changes in CVD prevalence rates in men and women and with aging. A key mechanism underlying these changes in vascular function is the endothelin (ET) system. Studies have demonstrated sex and sex hormone effects on endothelin-1 (ET-1), and its receptors ETA and ETB. However, with aging there is a dysregulation of this system resulting in an imbalance between vasodilation and vasoconstriction. Thus, ET-1 may play a role in the sex differences observed with vascular aging. While most research has been conducted in pre-clinical animal models, we describe more recent translational data in humans showing that the ET system is an important regulator of vascular dysfunction with aging and acts through sex-specific ET receptor mechanisms. In this review, we present translational evidence (cell, tissue, animal, and human) that the ET system is a key mechanism regulating sex-specific changes in vascular function with aging, along with therapeutic interventions to reduce ET-mediated vascular dysfunction associated with aging. More knowledge on the factors responsible for the sex differences with vascular aging allow for optimized therapeutic strategies to attenuate CVD risk in the expanding aging population.

Kidney Response to Chemotherapy-Induced Heart Failure: mRNA Analysis in Normotensive and Ren-2 Transgenic Hypertensive Rats.

The aim of the present study was to perform kidney messenger ribonucleic acid (mRNA) analysis in normotensive, Hannover Sprague–Dawley (HanSD) rats and hypertensive, Ren-2 renin transgenic rats (TGR) after doxorubicin-induced heart failure (HF) with specific focus on genes that are implicated in the pathophysiology of HF-associated cardiorenal syndrome. We found that in both strains renin and angiotensin-converting enzyme mRNA expressions were upregulated indicating that the vasoconstrictor axis of the renin–angiotensin system was activated. We found that pre-proendothelin-1, endothelin-converting enzyme type 1 and endothelin type A receptor mRNA expressions were upregulated in HanSD rats, but not in TGR, suggesting the activation of endothelin system in HanSD rats, but not in TGR. We found that mRNA expression of cytochrome P-450 subfamily 2C23 was downregulated in TGR and not in HanSD rats, suggesting the deficiency in the intrarenal cytochrome P450-dependent pathway of arachidonic acid metabolism in TGR. These results should be the basis for future studies evaluating the pathophysiology of cardiorenal syndrome secondary to chemotherapy-induced HF in order to potentially develop new therapeutic approaches.

Endothelial dysfunction in cancer patients before and after chemotherapy: focus on biomarkers

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): The reported study was funded by Russian Foundation for Basic Research (RFBR) project number 19-315-90034 Background. Nowadays gastric cancer is one of the leading causes of world cancer mortality. Modern chemotherapy (CT) significantly improves survival and quality of life among these patients. Unfortunately, anticancer drugs induce some biomolecular disorders, which influence endothelial dysfunction and microcirculation lesions, subsequently leading to vasculo- and cardiotoxicity. The aim To study the dynamics of endothelial dysfunction’s (ED) biomarkers (endothelin-1 (ET-1), von Willebrand factor (VWF)) in patients with gastric cancer before and after CT. Material and methods The study included 25 patients with histologically confirmed gastric cancer (adenocarcinoma) stage II - IV, who have been treated by CT including platinum compound (oxaliplatin, cisplatin) and fluoropyrimidine group (5-fluorouracil, capecitabine) and are proven to be cardiovasculotoxic. All patients underwent blood tests, computer nailfold capillaroscopy and finger photoplethysmography (non-invasive assessment of vascular wall stiffness and endothelial function), electrocardiography (ECG), 24-hour ECG, echocardiography before CT and within a month after the last course. Results The median patients’ age was 64 ± 13 years; 68% were male; 52% had a prior cardiac illness: arterial hypertension (n = 12, 48%), coronary artery disease (n = 7, 28%), chronic heart failure (n = 3, 12%). The data obtained showed that ET-1 median levels were below normal values and did not change during CT: 0,95pg/ml (0,6;1,4) vs. 0,94pg/ml (0,7;1,4), р<0,9 (N = 1–3pg/ml), before and after CT respectively. The level of VWF remained within normal ranges and did not significantly differ in cancer patients before and after treatment 0,75IU/ml (0,7;0,9) vs. 0,8IU/ml (0,74;0,9), р<0,6 (N = 0,5–1,5IU/ml). Even before CT, endothelial dysfunction was detected, which significantly worsened after the treatment (occlusion index (IO) before and after CT 1.7 (1.38; 1.9) vs. 1.3 (1.2; 1.5), p < 0.0002, respectively). During data analysis, significant correlations were found: between ET-1 level and IO (r = 0.554, p = 0,006), ET-1 and percentage of capillary recovery (r= -0.7, p = 0,029) [both parameters characterize functional abnormalities of the microvasculature], ET-1 and the quantity of supraventricular extrasystoles (r=-0.48, p = 0,032). Conclusion In this study, the dynamics of ED biomarkers in patients with gastric cancer were studied. Even though reliable changes were not proven for the assessed molecular parameters ET-1 and VWF during CT (supposing depletion of endothelin system, small patient cohort), the above parameters may be used for identifying early signs of close and long-term cardio/vasculotoxicity due to significant positive correlations with microvasculature lesions. Further bigger trials for identification of other accurate and effective laboratory methods of detecting early features of vasculotoxicity are required.

Hypertension meets osteoarthritis - revisiting the vascular aetiology hypothesis.

Osteoarthritis (OA) is a whole-joint disease characterized by subchondral bone perfusion abnormalities and neovascular invasion into the synovium and articular cartilage. In addition to local vascular disturbance, mounting evidence suggests a pivotal role for systemic vascular pathology in the aetiology of OA. This Review outlines the current understanding of the close relationship between high blood pressure (hypertension) and OA at the crossroads of epidemiology and molecular biology. As one of the most common comorbidities in patients with OA, hypertension can disrupt joint homeostasis both biophysically and biochemically. High blood pressure can increase intraosseous pressure and cause hypoxia, which in turn triggers subchondral bone and osteochondral junction remodelling. Furthermore, systemic activation of the renin-angiotensin and endothelin systems can affect the Wnt-β-catenin signalling pathway locally to govern joint disease. The intimate relationship between hypertension and OA indicates that endothelium-targeted strategies, including re-purposed FDA-approved antihypertensive drugs, could be useful in the treatment of OA.

The ring size of monocyclic ET-1 controls selectivity and signaling efficiency at both endothelin receptor subtypes.

Cardiovascular diseases (CVDs) like hypertension are a major cause for death worldwide. In the cardiovascular tissue, the endothelin system-consisting of the receptor subtypes A (ETA R) and B (ETB R) and the mixed agonist endothelin 1 (ET-1)-is a major key player in the regulation of vascular tone and blood pressure. Tight control of this system is required to maintain homeostasis; otherwise, the endothelin system can cause severe CVDs like pulmonary artery hypertension. The high sequence homology between both receptor subtypes limits the development of novel and selective ligands. Identification of small differences in receptor-ligand interactions and determination of selectivity constraints are crucial to fine-tune ligand properties and subsequent signaling events. Here, we report on novel ET-1 analogs and their detailed pharmacological characterization. We generated simplified ET-1-derived monocyclic peptides to provide an accessible synthesis route. By detailed in vitro characterization, we demonstrated that both G protein signaling and the subsequent arrestin recruitment of activated ETB R remain intact, whereas activation of the ETA R depends on the intramolecular ring size. Increasing of the intramolecular ring structure reduces activity at the ETA R and shifts the peptide toward ETB R selectivity. All ET-1 analogs displayed efficient ETB R-mediated signaling by G protein activation and arrestin 3 recruitment. Our study provides in-depth characterization of the ET-1/ETA R and ET-1/ETB R interactions, which has the potential for future development of endothelin-based drugs for CVD treatment. By identification of Lys9 for selective labeling, novel analogs for peptide-mediated shuttling by ET-1 are proposed.

Endothelin B receptors impair baroreflex function and increase blood pressure variability during high salt diet.

Baroreflex function is an integral component maintaining consistent blood pressure. Hypertension is often associated with baroreflex dysfunction, and environmental risk factors such as high salt diet exacerbate hypertension in subjects with baroreflex dysfunction. However, the interactions between high salt diet, baroreflex dysfunction, and hypertension are incompletely understood. The endothelin system is another potent mediator of blood pressure control especially in response to a high salt diet. We hypothesized that the endothelin B (ETB) receptor activation on adrenergic nerves decreases baroreflex sensitivity. We utilized male ETB receptor deficient (ETB-def) rats that express functional ETB receptors only on adrenergic nerves and transgenic (TG) controls to evaluate baroreflex function during normal (0.49% NaCl) and high (4.0% NaCl) salt diets. In conscious rats equipped with telemetry, ETB-def rats had an increased lability of systolic blood pressure (SBP) compared to TG controls as indicated by higher standard deviation (SD) of SBP under both normal (10.2±0.6 vs. 12.4±0.9mmHg, respectively, p=0.0001) and high (11.7±0.6 vs. 16.1±1.0mmHg, p=0.0001) salt diets. In anesthetized preparations, ETB-def rats displayed reduced heart rate (p genotype=0.0167) and renal sympathetic nerve (p genotype=0.0022) baroreflex sensitivity. We then gave male Sprague-Dawley rats the selective ETB receptor antagonist, A-192621 (10mg/kg/day), to block ETB receptors. Following ETB receptor antagonism, even though SBP increased (131±7 before vs. 152±8mmHg after, p<0.0001), the lability (standard deviation) of SBP decreased (9.3±2.0 vs. 7.1±1.1mmHg, p=0.0155). These data support our hypothesis that ETB receptors on adrenergic nerves contribute to baroreflex dysfunction.

Sex‐Specific Role of Endothelin‐A Receptors in the Cardiac Susceptibility to Ischemia/Reperfusion Insult in Adult Offspring Exposed to Prenatal Hypoxia

Introduction Fetal hypoxia, a common consequence of complicated pregnancies, leads to the development of cardiac dysfunction in adult offspring by impairing cardiac tolerance to an ischemia/reperfusion (I/R) insult. Extensive evidence demonstrates that cardiac I/R upregulates the endothelin-1 (ET-1) system leading to elevated levels of ET-1 (a peptide with potent physiological and pathophysiological effects on the cardiovascular system). Active ET-1 exerts its effects via the endothelin-A receptors (ETAR; of which enhanced activation has been associated with impaired post-I/R cardiac function) and endothelin-B receptors (ETBR; which are essential for post-I/R cardiac recovery). However, whether activation of ETAR contributes to cardiac dysfunction in adult offspring exposed to prenatal hypoxia is unknown. We hypothesize that, in adult offspring exposed to prenatal hypoxia, cardiac ETAR expression is increased, and its inhibition improves post-I/R cardiac recovery. Methods Pregnant Sprague-Dawley rats (n=4-6 dams/group) were exposed to normoxia (21% O2; normoxia) or hypoxia (11% O2; p-hypoxia) from gestational day 15-21 (term=22 days). Cardiac function was assessed ex vivo in 4-month old male and female offspring (n=1-2 offspring/dam) by subjecting isolated hearts to I/R (25 min. of ischemia with 40 min. of reperfusion). The contribution of ETAR to cardiac dysfunction was assessed by pre-infusion with an ETAR antagonist (ABT-627) before I/R (ABT-627 was recirculated during reperfusion). ETAR and ETBR levels were assessed in non-ischemic left ventricle tissues by Western blotting. Data (mean±SEM) were compared by two-way ANOVA (Sidak's post hoc test), or by unpaired t-test. Results : ABT-627 induced a dramatic reduction in cardiac recovery after I/R in prenatally hypoxic males compared to their respective controls (control: 60.5±16.3% vs ABT-627: 4.4±2.6%, p=0.009), without effect in normoxic males. In contrast, ABT-627 improved I/R recovery in prenatal hypoxia-exposed females (control: 53.5±10.6% vs ABT-627: 87±5.6%, p=0.05) with no effect in normoxic females. In males, exposure to prenatal hypoxia did not alter cardiac ETAR levels, but decreased ETBR levels compared to the normoxic group (normoxia: 100±3.2% vs p-hypoxia: 70.6±4%, p=0.0003), without changes in females. Conclusion Prenatal hypoxia alters the cardiac ET-1 system in a sex-specific manner. Inhibition of ETAR in prenatally hypoxic males impaired cardiac recovery post-I/R, potentially due to lower ETBR expression; while cardiac recovery was improved by ETAR inhibition in females. Activation of ETAR may thus be essential for cardiac tolerance to I/R in prenatally hypoxic males, while it may contribute to the development of cardiac dysfunction in females. Our data suggests that developmental influences and sex differences need to be considered during the implementation of therapeutic strategies to prevent the long-term effects of pregnancy complications on offspring cardiac health.

Calcification of aortic valvular interstitial cells induced by endothelin receptor blockers

Calcified aortic stenosis (AS) is the most common acquired valvulopathy for which there is still no pharmacological treatment. Endothelin-1 (ET-1) is not only a powerful vasoconstrictor but also a pro-inflammatory and pro-fibrotic peptide whose role in AS remains unclear. The aim of this study was to characterize the role of ET-1 in the aortic valve calcification. Valvular endothelial cells (VECs), isolated from human aortic valves, were cultured in a cell perfusion system to assess ET-1 production in different fluid flow shear stress conditions. In addition, valvular interstitial cells (VICs) were cultured in a pro-calcifying culture medium (inorganic phosphate: 2 mM) with or without small-molecule and monoclonal antibody ET A and ET B receptor antagonists during 10 days. Calcium content was assessed using an o-cresolphtalein-based assay and red alizarin staining. VEC prepro-ET-1 and VIC osteogenic mRNA expression levels were evaluated by RTqPCR. Visualization of VIC ET A and ET B receptor was performed by immunohistochemistry. Turbulent shear stress, mimicking the flow conditions suffered by the valve at the aortic side that is the most prone to calcify, increased VEC prepro-ET-1 mRNA expression level and ET-1 release compared to laminar shear stress. Unexpectedly, calcium content and alizarin red staining of VICs were increased after blockade of ET B receptor and this effect was potentiated by concomitant blockade of ET A receptor. The mRNA expression of osteopontin, RUNX2, and BMP2 was similarly increased by ET B blockade. A perinuclear localization of ET A and ET B receptors in VICS was observed, suggesting a direct implication in the regulation of calcification genes. These results support a protective role of the endothelin system against the development of AS. Further studies are warranted to characterize the intracellular pathways and to confirm these results in ex vivo and in vivo models.

Association of Gene Polymorphisms of Some Endothelial Factors with Stent Reendothelization after Elective Coronary Artery Revascularization.

Restenosis remains the main complication after percutaneous coronary interventions in patients with coronary heart disease. The causes of its development include, in particular, genetic factors. We studied polymorphic loci of genes encoding endothelin-1 (EDN1 rs5370), endothelin-1 receptor (EDNRA rs5333), endothelin-converting enzyme (ECE1 rs1076669), and endothelial NO synthase (eNOS rs1549758, eNOS rs1799983, and eNOS rs2070244) in the context of in-stent restenosis development. It was found that the analyzed polymorphisms of the endothelin system genes were more significant for patients aged ≥ 65 years, while the polymorphic loci of the endothelial NO synthase gene (eNOS rs1799983 and eNOS rs1549758) were predominantly associated with time of in-stent restenosis. The obtained results can be useful for comprehensive assessment of the restenosis risk factors and the choice of optimal treatment for patients with coronary heart disease before elective surgical intervention.

Therapeutic Effect of Endothelin-Converting Enzyme Inhibitor on Chronic Kidney Disease through the Inhibition of Endoplasmic Reticulum Stress and the NLRP3 Inflammasome.

Chronic inflammation and oxidative stress significantly contribute to the development and progression of chronic kidney disease (CKD). The NOD-like receptor family pyrin containing domain-3 (NLRP3) inflammasome plays a key role in the inflammatory response. The renal endothelin (ET) system is activated in all cases of CKD. Furthermore, ET-1 promotes renal cellular injury, inflammation, fibrosis and proteinuria. Endothelin-converting enzymes (ECEs) facilitate the final processing step of ET synthesis. However, the roles of ECEs in CKD are not clear. In this study, we investigated the effects of ETs and ECEs on kidney cells. We found that ET-1 and ET-2 expression was significantly upregulated in the renal tissues of CKD patients. ET-1 and ET-2 showed no cytotoxicity on human kidney tubular epithelial cells. However, ET-1 and ET-2 caused endoplasmic reticulum (ER) stress and NLRP3 inflammasome activation in tubular epithelial cells. The ECE inhibitor phosphoramidon induced autophagy. Furthermore, phosphoramidon inhibited ER stress and the NLRP3 inflammasome in tubular epithelial cells. In an adenine diet-induced CKD mouse model, phosphoramidon attenuated the progression of CKD by regulating autophagy, the NLRP3 inflammasome and ER stress. In summary, these findings showed a new strategy to delay CKD progression by inhibiting ECEs through autophagy activation and restraining ER stress and the NLRP3 inflammasome.

Endothelin B receptor dysfunction mediates elevated myogenic tone in cerebral arteries from aged male Fischer 344 rats

The human brain requires adequate cerebral blood flow to meet the high demand for nutrients and to clear waste products. With age, there is a chronic reduction in cerebral blood flow in small resistance arteries that can eventually limit proper brain function. The endothelin system is a key mediator in the regulation of cerebral blood flow, but the contributions of its constituent receptors in the endothelial and vascular smooth muscle layers of cerebral arteries have not been well defined in the context of aging. We isolated posterior cerebral arteries from young and aged Fischer 344 rats, as well as ETB receptor knock-out rats and mounted the vessels in plexiglass pressure myograph chambers to measure myogenic tone in response to increasing pressure and targeted pharmacological treatments. We used an ETA receptor antagonist (BQ-123), an ETB receptor antagonist (BQ-788), endothelin-1, an endothelin-1 synthesis inhibitor (phosphoramidon), and vessel denudation to dissect the roles of each receptor in aging vasculature. Aged rats exhibited a higher myogenic tone than young rats, and the tone was sensitive to the ETA antagonist, BQ-123, but insensitive to the ETB antagonist, BQ-788. By contrast, the tone in the vessels from young rats was raised by BQ-788 but unaffected by BQ-123. When the endothelial layer that is normally enriched with ETB1 receptors was removed from young vessels, myogenic tone increased. However, denudation of the endothelial layer did not influence vessels from aged animals. This indicated that endothelial ETB1 receptors were not functional in the vessels from aged rats. There was also an increase in ETA receptor expression with age, whereas ETB receptor expression remained constant between young and aged animals. These results demonstrate that in young vessels, ETB1 receptors maintain a lower myogenic tone, but in aged vessels, a loss of ETB receptor activity allows ETA receptors in vascular smooth muscle cells to raise myogenic tone. Our findings have potentially important clinical implications for treatments to improve cerebral perfusion in older adults with diseases characterized by reduced cerebral blood flow.

Interplay of the Circadian Clock and Endothelin System

The peptide hormone endothelin-1 and its receptors are linked to several disease states. Pharmacological inhibition of this pathway has proven beneficial in pulmonary hypertension, yet its potential in other disease states remains to be realized. This review considers an often understudied aspect of endothelin biology, circadian rhythm regulation and how understanding the intersection between endothelin signaling and the circadian clock may be leveraged to realize the potential of endothelin-based therapeutics.

1195. Influence of Histoplasma capsulatum Infection on Endothelin-1 mRNA Gene Expression in Bone Marrow Derived Macrophages

BackgroundEndothelin-1 (ET-1) is increasingly recognized as an immune modulator; it exerts a pro-inflammatory effect by increasing the release of cytokines like interferon gamma. ET-1 is secreted by a variety of cells such as macrophages, neurons and endothelial cells. Activation of the endothelin system has been implicated in the pathogenesis of sepsis caused by bacteria, viruses and even parasites. However, there are no published studies that have explored the role of ET-1 in Histoplasma capsulatum infection. Studying the role of ET-1 in histoplasmosis is important because understanding its role in the host defense mechanism may serve as the foundation for future discovery of novel therapeutic options.MethodsBone marrow cells were isolated from mice and set up for tissue culture. Bone marrow derived macrophages (BMDM) were harvested after 5-7 days of incubation, and infected with varying ratios (0.5,1 and 5) of yeasts to macrophages. RNA was extracted from the BMDM after 3, 6, 24 and 48 hours of infection. For comparison, RNA was also extracted from uninfected BMDM at the same time points. Real-time PCR (polymerase chain reaction) was performed on complementary DNA. ET-1 (Edn1) messenger RNA (mRNA) gene expression was quantified relative to the expression of the house keeping /endogenous control gene that encodes for beta-2 microglobulin (B2m).ResultsIn BMDM infected with H. capsulatum there was upregulation of Edn1 after 3, 6 and 24 hours of infection. During this same time points, the expression of ET-1 mRNA in the uninfected BMDM remained constant. Expression of Edn1 was highest in the BMDM infected with 5x H. capsulatum after 3 and 6 hours of infection. After 24 hours, the expression of ET-1 mRNA decreased markedly in all concentrations of H. capsulatum. At 48 hours post-infection the Edn1 was downregulated in the 0.5,1 and 5-fold quantities of H. capsulatum across all time the time intervals.Figure 1 ConclusionResults from this study indicate that H. capsulatum infection induced an upregulation of the Edn-1 in BMDM. This may correlate with an increase in levels of ET-1 production by the BMDM in the face of H. capsulatum infection. These results provide a platform in which to examine the influence of ET-1 on the host response to this fungus.Disclosures All Authors: No reported disclosures

Combination of hyperglycaemia and hyperlipidaemia induces endothelial dysfunction: Role of the endothelin and nitric oxide systems.

Endothelial dysfunction (ED) is a key feature of diabetes and is a major cause of diabetic vasculopathy. Diabetic patients who also exhibit hyperlipidaemia suffer from accelerated vascular complications. While the deleterious effects of high glucose levels (HG) and hyperlipidaemia alone on ED are well established, the effects of combined hyperlipidaemia and HG have not been thoroughly studied. Therefore, the current study examines whether HG and hyperlipidaemia exert synergistic ED, and explores the mechanisms underlying this phenomenon. We applied multi‐disciplinary approaches including cultured HUVECs and HMEC‐1 as well as knockout mice CByJ.129S7(B6)‐Ldlrtm1Her/J (LDLR−/−) to investigate the mechanisms underlying combined HG and hyperlipidaemia‐induced ED. Incremental doses of glucose in the presence or absence of OxLDL were added to HUVECs and HMEC‐1. After 5 days, the status of nitric oxide (NO) and endothelin (ET)‐1 systems as well as their signal transduction were assessed using Western blot, ELISA and immunoreactive staining. The effects of chronic combination of HG and hyperlipidaemia on endothelial integrity and function as well as alterations in circulatory NO and ET‐1 systems were examined in knockout mice LDLR−/− and their wild‐type. HUVEC cells exposed to HG and OxLDL displayed enhanced ET‐1 production, more than HG or OxLDL when added alone. Overproduction of ET‐1 stems from up‐regulation of endothelin converting enzyme (ECE)‐1 as observed under these conditions. In contrast, combination of HG and OxLDL dramatically decreased both total endothelial NO synthase (eNOS) by 60%, and activated eNOS (peNOS) by 80%. Moreover, NRF2 decreased by 42% and its active form (pNRF2) by 56%, as compared to baseline. Likewise, ETB levels decreased by 64% from baseline on endothelial cells. Furthermore, diabetic LDLR−/− mice displayed a higher blood pressure, plasma triglycerides, cholesterol, ET‐1 and NO2/NO3 levels, when compared with normoglycemic LDLR−/− and BALB mice. Combined hyperglycaemia and hyperlipidaemia activates the ET system and attenuates the nitric oxide system with the Nrf2 signalling pathway. These findings suggest that perturbations in these paracrine systems may contribute to ED.

Рівні ендотеліну-1 та тестостерону в крові хворих на цукровий діабет 1-го та 2-го типів

Із цукровим діабетом (ЦД) пов’язана ендотеліальна дисфункція (ЕД) — одна з ключових патологічних подій у розвитку хронічних діабетичних ускладнень. Важливим ефектом ЕД є збільшення продукції та біологічної активності ендотеліну (ЕТ). ET‑1, який виробляється переважно в ендотелії, є основною серцево-судинною ізоформою ендотелінової системи. ЦД — одне із захворювань, пов’язаних із патологічно підвищеним рівнем ЕТ. Отримані докази того, що андрогени можуть грати певну роль у визначенні специфічного для статі артеріального тиску. Чоловіки мають більш високий ризик розвитку ішемічної хвороби серця або гіпертонічної хвороби порівняно з жінками в пременопаузі. Мета — визначення концентрації ЕТ‑1 та тестостерону (Т) в крові хворих на цукровий діабет першого (ЦД1) та другого (ЦД2) типів із різним індексом маси тіла (ІМТ) та різних вікових категорій. Матеріал і методи. Рівень ET‑1 оцінювали методом ІФА в 103 осіб: 17 здорових осіб та 86 пацієнтів із ЦД1 і ЦД2. Для визначення концентрації ET‑1 використовували набір Endotelin (1-21) EIA. Загальний Т визначали за допомогою набору EIA‑1559. Результати. У всіх пацієнтів із діабетом рівень ЕТ‑1 у крові був значно вищим, ніж в осіб контрольної групи. Різниця в кількості ЕТ‑1 у крові пацієнтів із ЦД1 і ЦД2 була невірогідною. Рівень ЕТ‑1 у чоловіків був вищим, ніж у жінок у середньому на 37%. У групі з вищим індексом маси тіла кількість ET‑1 була вищою на 71%, а Т — нижчою на 25%. Рівень ЕТ‑1 у віковій групі до 50 років був нижчим, ніж у старшій групі для обох типів ЦД (123% для ЦД1 і 148% для ЦД2), а кількість Т у хворих на ЦД2 — вища майже на 20%. У групі хворих на ЦД2 з рівнем Т&lt;3 нг/мл концентрація ЕТ‑1 у крові була вищою, ніж у хворих із рівнем Т&gt;3 нг/мл (відповідно 0,550 фмоль/мл і 0,392 фмоль/мл). Висновки. У чоловіків, хворих на ЦД2 з ожирінням спостерігається підвищення концентрації ЕТ‑1 і зниження рівня Т. Ці показники, напевно, безпосередньо не пов’язані з вмістом глікованого гемоглобіну (Нв1Ас). Із віком рівень ЕТ‑1 у крові хворихна ЦД зростає, а рівень Т знижується. Ці процеси можуть бути взаємопов’язаними. Концентрація ЕТ‑1 у крові в чоловіків, хворих на ЦД обох типів вірогідно вища, ніж у жінок.

Preeclampsia: Linking Placental Ischemia with Maternal Endothelial and Vascular Dysfunction.

Preeclampsia (PE), a hypertensive disorder, occurs in 3% to 8% of pregnancies in the United States and affects over 200,000 women and newborns per year. The United States has seen a 25% increase in the incidence of PE, largely owing to increases in risk factors, including obesity and cardiovascular disease. Although the etiology of PE is not clear, it is believed that impaired spiral artery remodeling of the placenta reduces perfusion, leading to placental ischemia. Subsequently, the ischemic placenta releases antiangiogenic and pro-inflammatory factors, such as cytokines, reactive oxygen species, and the angiotensin II type 1 receptor autoantibody (AT1-AA), among others, into the maternal circulation. These factors cause widespread endothelial activation, upregulation of the endothelin system, and vasoconstriction. In turn, these changes affect the function of multiple organ systems including the kidneys, brain, liver, and heart. Despite extensive research into the pathophysiology of PE, the only treatment option remains early delivery of the baby and importantly, the placenta. While premature delivery is effective in ameliorating immediate risk to the mother, mounting evidence suggests that PE increases risk of cardiovascular disease later in life for both mother and baby. Notably, these women are at increased risk of hypertension, heart disease, and stroke, while offspring are at risk of obesity, hypertension, and neurological disease, among other complications, later in life. This article aims to discuss the current understanding of the diagnosis and pathophysiology of PE, as well as associated organ damage, maternal and fetal outcomes, and potential therapeutic avenues. © 2021 American Physiological Society. Compr Physiol 11:1315-1349, 2021.

Monitoring Endothelin-A Receptor Expression during the Progression of Atherosclerosis.

Cardiovascular disease remains the most frequent cause of death worldwide. Atherosclerosis, an underlying cause of cardiovascular disease, is an inflammatory disorder associated with endothelial dysfunction. The endothelin system plays a crucial role in the pathogenesis of endothelial dysfunction and is involved in the development of atherosclerosis. We aimed to reveal the expression levels of the endothelin-A receptor (ETAR) in the course of atherogenesis to reveal possible time frames for targeted imaging and interventions. We used the ApoE−/− mice model and human specimens and evaluated ETAR expression by quantitative rtPCR (qPCR), histology and fluorescence molecular imaging. We found a significant upregulation of ETAR after 22 weeks of high-fat diet in the aortae of ApoE−/− mice. With regard to translation to human disease, we applied the fluorescent probe to fresh explants of human carotid and femoral artery specimens. The findings were correlated with qPCR and histology. While ETAR is upregulated during the progression of early atherosclerosis in the ApoE−/− mouse model, we found that ETAR expression is substantially reduced in advanced human atherosclerotic plaques. Moreover, those expression changes were clearly depicted by fluorescence imaging using our in-house designed ETAR-Cy 5.5 probe confirming its specificity and potential use in future studies.

Evaluation of Urinary Big Endothelin-1 in Feline Spontaneous CKD.

Simple SummaryChronic kidney disease is a common and progressive disease of elderly cats. It is a cause of pet suffering and owner expense. Biologic biomarkers for early diagnosis and for noninvasive evaluation of kidney damage are certainly useful in both research and clinical practice. In this study, we evaluated the biomarker big endotelin-1 in the urine of cats affected with chronic kidney disease. Big endothelin-1 is molecule linked to inflammation and pressure regulation, and it was not previously evaluated in nephropathic cats. We found that urinary big endothelin was increased in patients at late stage of the disease and in patients with proteinuria (a marker of kidney damage). Despite that, big endothelin 1 seemed not to be a useful biomarker for disease progression. According to results of this preliminary study, we suggest this biomarker for future research on feline kidney disease.The endothelin-1 (ET-1) system has been implicated in the development and progression of chronic kidney disease (CKD). No information on big ET-1 in feline urine is available. The purpose of this study was to evaluate if urinary big endothelin-1 (bigET-1) is associated with feline CKD. Sixty urine samples were prospectively collected from 13 healthy cats at risk of developing CKD and 22 cats with CKD of different International Renal Interest Society (IRIS) stages (1–4). Urinary bigET-1 was measured using a commercially available ELISA. BigET-1 normalized to urine creatinine (bigET-1:UC) was compared amongst stages and substages, as proposed by IRIS, and correlated with serum creatinine concentration, proteinuria and blood pressure. BigET-1:UC at the time of inclusion was compared between cats that remained stable and cats that progressed after 12 months. BigET-1:UC was significantly higher (p = 0.002) in cats at IRIS stages 3–4 (median: 21.9; range: 1.88–55.6), compared to all other stages, and in proteinuric (n = 8, median: 11.0; range: 0.00–46.4) compared with nonproteinuric cats (n = 38 median: 0.33; range: 0.00–55.6) (p = 0.029). BigET-1:UC was not associated with CKD progression. Urinary bigET-1 increased in advanced stages of CKD and in proteinuric patients, suggesting that ET-1 may be indicative of the severity of feline CKD.

Dysregulation of Endothelin-1: Implications for Health Disparities in Alzheimer's Disease.

Alzheimer’s disease (AD) and related dementias disproportionately impact racial and ethnic minorities. The racial and ethnic disparities in AD could be explained by differences in cerebral vascular disease pathology. Endothelin-1 (ET-1) is a potent vasoconstrictive peptide that regulates smooth muscle, endothelial cell, and pericyte contractions that may result in cerebral vascular constriction, leading to cerebral hypoperfusion; over time, ET-1 may result in neuronal injury contributing to the pathology of AD. Upregulation of the ET-1 system has been observed in African Americans when compared with non-Hispanic Whites. The role of the ET-1 system as a driver of ethnic disparities in AD requires further investigation. Targeting of the ET-1 system as a therapeutic intervention that could impact AD progression also needs further study. Dysregulation of ET-1 in Hispanic/Latino populations largely have been unexplored. Genetics linking ET-1 dysregulation and racial disparities in AD also needs further investigation. In this review, I examine how AD effects underserved minority populations and how dysregulation of the ET-1 system specifically predisposes ethnic minorities to AD. In addition, I examine the molecular interactions of the ET-1 system and amyloid beta, the role the ET-1 system in neurodegeneration, potential therapeutics for ET-1 dysregulation, and the impact on AD progression.