The human endothelin family: three structurally and pharmacologically distinct isopeptides predicted by three separate genes

Genetic diversity and signatures of selection in Icelandic horses and Exmoor ponies

BACKGROUND

The Icelandic horse and Exmoor pony are ancient, native breeds, adapted to harsh environmental conditions and they have both undergone severe historic bottlenecks. However, in modern days, the selection pressures on these breeds differ substantially. The aim of this study was to assess genetic diversity in both breeds through expected (HE) and observed heterozygosity (HO) and effective population size (Ne). Furthermore, we aimed to identify runs of homozygosity (ROH) to estimate and compare genomic inbreeding and signatures of selection in the breeds.

RESULTS

HO was estimated at 0.34 and 0.33 in the Icelandic horse and Exmoor pony, respectively, aligning closely with HE of 0.34 for both breeds. Based on genomic data, the Ne for the last generation was calculated to be 125 individuals for Icelandic horses and 42 for Exmoor ponies. Genomic inbreeding coefficient (FROH) ranged from 0.08 to 0.20 for the Icelandic horse and 0.12 to 0.27 for the Exmoor pony, with the majority of inbreeding attributed to short ROHs in both breeds. Several ROH islands associated with performance were identified in the Icelandic horse, featuring target genes such as DMRT3, DOCK8, EDNRB, SLAIN1, and NEURL1. Shared ROH islands between both breeds were linked to metabolic processes (FOXO1), body size, and the immune system (CYRIB), while private ROH islands in Exmoor ponies were associated with coat colours (ASIP, TBX3, OCA2), immune system (LYG1, LYG2), and fertility (TEX14, SPO11, ADAM20).

CONCLUSIONS

Evaluations of genetic diversity and inbreeding reveal insights into the evolutionary trajectories of both breeds, highlighting the consequences of population bottlenecks. While the genetic diversity in the Icelandic horse is acceptable, a critically low genetic diversity was estimated for the Exmoor pony, which requires further validation. Identified signatures of selection highlight the differences in the use of the two breeds as well as their adaptive trait similarities. The results provide insight into genomic regions under selection pressure in a gaited performance horse breed and various adaptive traits in small-sized native horse breeds. This understanding contributes to preserving genetic diversity and population health in these equine populations.

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.

Endothelin-3 Suppresses Luteinizing Hormone Receptor Expression by Regulating the cAMP-PKA Pathway in Hen Granulosa Cells

Previous research identified the expression of EDN3 in granulosa cells of preovulatory follicles in chickens. Notably, the expression level of EDN3 in Silky Fowl with low egg-laying performance was significantly higher than that in high-yield laying breed White Leghorn. Given the crucial role of granulosa cells in follicular development and maturation, it is very important to study the effect of EDN3 on the biological function of granular cells. In this study, an EDN3 overexpression plasmid was constructed and transfected into granular cells. The viability of these cells was detected using quantiative (qPCR), Cell Counting Kit-8 (CCK8), and 5-Ethynyl-2'-deoxyuridine (EdU) assays. Gonadal hormone synthesis was detected using enzyme-linked immunosorbent assay (ELISA) techniques. Finally, transcriptome sequencing was employed to identify differentially expressed genes. Result showed thatoverexpression of EDN3 was observed to promote cell viability. In addition, it significantly inhibits the expressions of LHR and cAMP-PKA signaling pathways. Cell transcriptome sequencing data displayed that EDN3 can upregulate energy metabolism and immune-related signaling pathways, whereas follicle maturation and the GnRH signaling pathway were downregulated. In conclusion, this study demonstrates that EDN3 can enhance granulosa cell viability and inhibit the expression of LHCGR, a process likely mediated through the cAMP-PKA signaling pathway. However, further evidence is required to substantiate the regulatory relationship between EDN3 and the cAMP-PKA signaling pathway.

Study of some components of the influence and formation of blood flow in patients with "slow flow"

BACKGROUND

"Slow flow" is one very important concept in modern fundamental and clinical biomedicine. Slow coronary flow is indicative of delayed filling of the terminal coronary artery vessels, occurring in the absence of significant coronary stenosis. This group patient of patients exhibits a high incidence of disability and represents a significant financial and material burden for the state and the healthcare system in general.

OBJECTIVE

The primary objective of our study was to examine patients with slow coronary flow.

METHODS

We studied the standard parameters recommended by the international health care system (electrocardiography (by Medica QRS-12, Germany), through the electrical activity of a patient's heart by the electrical impulses (beating) of the heart; HC1(Germany); coagulogramma by Coatron M1 (Germany), troponin by AQT 90 (Germany); general blood test we used automatic human counting device HC1(Germany). Also, we investigate the original parameters (non-standard parameters, which we use in this pilot study) that we were first studied for this diagnosis and non-standard parameters.

RESULTS

A general blood test showed that patients with slow flow had a higher blood leukocyte count than the control group, but the amount of hemoglobin was normal, the hematocrit was much higher than in the control group, and the platelet count was close to the lower limit of clinical standards.We obtained details of blood flow by coagulation situation, such as prothrombin time, prothrombin index, international normalized ratio, activated partial thromboplastin time, thrombin time, fibrinogen, and rheological properties such as index of erythrocyte aggregability, index of erythrocyte deformability, plasma viscosity, in silico blood rheological index.

CONCLUSSION

Blood flow can be considered as a superposition of vortices with similar frequencies and wave vectors that change after bifurcations or other obstacles in the vascular network. These factors together determine the conditions for structuring the flow of moving blood. Disruption or alteration of these factors results in slow flow. It has been found that the speed of blood flow in the coronary arteries depends on changes in the number and function of red blood cells. Slow flow is directly influenced by the aggregation and deformation of red blood cells, their number, and plasma viscosity. Consequently, the rheological status plays a crucial role in determining blood flow and its velocity.

Intrinsic organization of the corpus callosum

The corpus callosum-the largest commissural fiber system connecting the two cerebral hemispheres-is considered essential for bilateral sensory integration and higher cognitive functions. Most studies exploring the corpus callosum have examined either the anatomical, physiological, and neurochemical organization of callosal projections or the functional and/or behavioral aspects of the callosal connections after complete/partial callosotomy or callosal lesion. There are no works that address the intrinsic organization of the corpus callosum. We review the existing information on the activities that take place in the commissure in three sections: I) the topographical and neurochemical organization of the intracallosal fibers, II) the role of glia in the corpus callosum, and III) the role of the intracallosal neurons.

Comprehensive expression analysis of hormone-like substances in the subcutaneous adipose tissue of the common bottlenose dolphin Tursiops truncatus

Marine mammals possess a specific subcutaneous fat layer called blubber that not only insulates and stores energy but also secretes bioactive substances. However, our understanding of its role as a secretory organ in cetaceans is incomplete. To exhaustively explore the hormone-like substances produced in dolphin subcutaneous adipose tissue, we performed seasonal blubber biopsies from captive female common bottlenose dolphins (Tursiops truncatus; N = 8, n = 32) and analyzed gene expression via transcriptomics. Analysis of 186 hormone-like substances revealed the expression of 58 substances involved in regulating energy metabolism, tissue growth/differentiation, vascular regulation, immunity, and ion/mineral homeostasis. Adiponectin was the most abundantly expressed gene, followed by angiopoietin protein like 4 and insulin-like growth factor 2. To investigate the endocrine/secretory responses of subcutaneous adipose tissue to the surrounding temperature, we subsequently compared the mean expression levels of the genes during the colder and warmer seasons. In the colder season, molecules associated with appetite suppression, vasodilation, and tissue proliferation were relatively highly expressed. In contrast, warmer seasons enhanced the expression of substances involved in tissue remodeling, immunity, metabolism, and vasoconstriction. These findings suggest that dolphin blubber may function as an active secretory organ involved in the regulation of metabolism, appetite, and tissue reorganization in response to changes in the surrounding environment, providing a basis for elucidating the function of hormone-like substances in group-specific evolved subcutaneous adipose tissue.

Role of Vasoactive Hormone-Induced Signal Transduction in Cardiac Hypertrophy and Heart Failure

Heart failure is the common concluding pathway for a majority of cardiovascular diseases and is associated with cardiac dysfunction. Since heart failure is invariably preceded by adaptive or maladaptive cardiac hypertrophy, several biochemical mechanisms have been proposed to explain the development of cardiac hypertrophy and progression to heart failure. One of these includes the activation of different neuroendocrine systems for elevating the circulating levels of different vasoactive hormones such as catecholamines, angiotensin II, vasopressin, serotonin and endothelins. All these hormones are released in the circulation and stimulate different signal transduction systems by acting on their respective receptors on the cell membrane to promote protein synthesis in cardiomyocytes and induce cardiac hypertrophy. The elevated levels of these vasoactive hormones induce hemodynamic overload, increase ventricular wall tension, increase protein synthesis and the occurrence of cardiac remodeling. In addition, there occurs an increase in proinflammatory cytokines and collagen synthesis for the induction of myocardial fibrosis and the transition of adaptive to maladaptive hypertrophy. The prolonged exposure of the hypertrophied heart to these vasoactive hormones has been reported to result in the oxidation of catecholamines and serotonin via monoamine oxidase as well as the activation of NADPH oxidase via angiotensin II and endothelins to promote oxidative stress. The development of oxidative stress produces subcellular defects, Ca2+-handling abnormalities, mitochondrial Ca2+-overload and cardiac dysfunction by activating different proteases and depressing cardiac gene expression, in addition to destabilizing the extracellular matrix upon activating some metalloproteinases. These observations support the view that elevated levels of various vasoactive hormones, by producing hemodynamic overload and activating their respective receptor-mediated signal transduction mechanisms, induce cardiac hypertrophy. Furthermore, the occurrence of oxidative stress due to the prolonged exposure of the hypertrophied heart to these hormones plays a critical role in the progression of heart failure.

Association of Gene Polymorphisms with Normal Tension Glaucoma: A Systematic Review and Meta-Analysis

BACKGROUND

Normal tension glaucoma (NTG) is becoming a more and more serious problem, especially in Asia. But the pathological mechanisms are still not illustrated clearly. We carried out this research to uncover the gene polymorphisms with NTG.

METHODS

We searched in Web of Science, Embase, Pubmed and Cochrane databases for qualified case-control studies investigating the association between single nucleotide polymorphisms (SNPs) and NTG risk. Odds ratios (ORs) and 95% confidence intervals (CIs) for each SNP were estimated by fixed- or random-effect models. Sensitivity analysis was also performed to strengthen the reliability of the results.

RESULTS

Fifty-six studies involving 33 candidate SNPs in 14 genetic loci were verified to be eligible for our meta-analysis. Significant associations were found between 16 SNPs (rs166850 of OPA1; rs10451941 of OPA1; rs735860 of ELOVL5; rs678350 of HK2; c.603T>A/Met98Lys of OPTN; c.412G>A/Thr34Thr of OPTN; rs10759930 of TLR4; rs1927914 of TLR4; rs1927911 of TLR4; c.*70C>G of EDNRA; rs1042522/-Arg72Pro of P53; rs10483727 of SIX1-SIX6; rs33912345 of SIX1-SIX6; rs2033008 of NCK2; rs3213787 of SRBD1 and c.231G>A of EDNRA) with increased or decreased risk of NTG.

CONCLUSIONS

In this study, we confirmed 16 genetic polymorphisms in 10 genes (OPA1, ELOVL5, HK2, OPTN, TLR4, EDNRA, P53, NCK2, SRBD1 and SIX1-SIX6) were associated with NTG.

Maximizing the Therapeutic Effect of Endothelin Receptor Antagonists in Pulmonary Fibrosis: A Paradigm for Treating the Disease

Using a lipopolysaccharide model of acute lung injury, we previously showed that endothelin-1 (ET-1), a potent mediator of vasoconstriction, may act as a "gatekeeper" for the influx of inflammatory cells into the lung. These studies provided a rationale for testing the effect of HJP272, an endothelin receptor antagonist (ERA), in hamster models of pulmonary fibrosis induced by intratracheal instillation of either bleomycin (BLM) or amiodarone (AM). To determine the temporal effects of blocking ET-1 activity, animals were given HJP272 either 1 h before initiation of lung injury or 24 h afterward. The results indicated that pretreatment with this agent caused significant reductions in various inflammatory parameters, whereas post-treatment was ineffective. This finding suggests that ERAs are only effective at a very early stage of pulmonary fibrosis and explains their lack of success in clinical trials involving patients with this disease. Nevertheless, ERAs could serve as prophylactic agents when combined with drugs that may induce pulmonary fibrosis. Furthermore, developing a biomarker for the initial changes in the lung extracellular matrix could increase the efficacy of ERAs and other therapeutic agents in preventing the progression of the disease. While no such biomarker currently exists, we propose the ratio of free to peptide-bound desmosine, a unique crosslink of elastin, as a potential candidate for detecting the earliest modifications in lung microarchitecture associated with pulmonary fibrosis.

Endothelin receptor antagonists in diabetic and non-diabetic chronic kidney disease

Chronic kidney disease (CKD) is one of the major causes of morbidity and mortality, affecting >800 million persons globally. While we still lack efficient, targeted therapies addressing the major underlying pathophysiologic processes in CKD, findings of several recent trials have brought about a shifting landscape of promising therapies. The endothelin system has been implicated in the pathophysiology of CKD and endothelin receptor antagonists are one class of drugs for which we have increasing evidence of efficacy in these patients. In this review we summarize the most recent findings on the safety and efficacy of endothelin receptor antagonists in diabetic and non-diabetic CKD, future directions of research and upcoming treatments.

Understanding the pathogenesis of coronary slow flow: Recent advances

Coronary slow flow is taken to be indicative of delayed filling of terminal vessels of the coronary arteries in the absence of coronary stenosis, as detected using coronary angiography. Patients suffering from coronary slow flow typically experience recurrent chest pain, thereby markedly affecting their quality of life. The etiology and pathogenesis of coronary slow flow, which is gradually attracting clinical attention, have yet to be sufficiently established, although it is currently believed that they may be associated with endothelial dysfunction in the coronary arteries, inflammatory response, abnormalities in microvascular reserve function, subclinical atherosclerosis, blood cell and platelet abnormalities, and genetic factors. In this review, we provide a brief overview of recent progress in research on the pathogenesis of coronary slow flow with a view toward elucidating the possible underlying pathogenesis and identify targets and directions for the treatment of this condition.

Endothelin signaling in development

Since the discovery of endothelin 1 (EDN1) in 1988, the role of endothelin ligands and their receptors in the regulation of blood pressure in normal and disease states has been extensively studied. However, endothelin signaling also plays crucial roles in the development of neural crest cell-derived tissues. Mechanisms of endothelin action during neural crest cell maturation have been deciphered using a variety of in vivo and in vitro approaches, with these studies elucidating the basis of human syndromes involving developmental differences resulting from altered endothelin signaling. In this Review, we describe the endothelin pathway and its functions during the development of neural crest-derived tissues. We also summarize how dysregulated endothelin signaling causes developmental differences and how this knowledge may lead to potential treatments for individuals with gene variants in the endothelin pathway.

Neurovascular dysfunction in glaucoma

Retinal ganglion cells, the neurons that die in glaucoma, are endowed with a high metabolism requiring optimal provision of oxygen and nutrients to sustain their activity. The timely regulation of blood flow is, therefore, essential to supply firing neurons in active areas with the oxygen and glucose they need for energy. Many glaucoma patients suffer from vascular deficits including reduced blood flow, impaired autoregulation, neurovascular coupling dysfunction, and blood-retina/brain-barrier breakdown. These processes are tightly regulated by a community of cells known as the neurovascular unit comprising neurons, endothelial cells, pericytes, Müller cells, astrocytes, and microglia. In this review, the neurovascular unit takes center stage as we examine the ability of its members to regulate neurovascular interactions and how their function might be altered during glaucomatous stress. Pericytes receive special attention based on recent data demonstrating their key role in the regulation of neurovascular coupling in physiological and pathological conditions. Of particular interest is the discovery and characterization of tunneling nanotubes, thin actin-based conduits that connect distal pericytes, which play essential roles in the complex spatial and temporal distribution of blood within the retinal capillary network. We discuss cellular and molecular mechanisms of neurovascular interactions and their pathophysiological implications, while highlighting opportunities to develop strategies for vascular protection and regeneration to improve functional outcomes in glaucoma.

The Tetraspanin Tspan8 Associates with Endothelin Converting Enzyme ECE1 and Regulates Its Activity

Tspan8 is a member of the tetraspanins family of cell surface molecules. The ability of tetraspanins to organize membrane microdomains with other membrane molecules and interfere with their function suggests that they could act as surface integrators of external or internal signals. Among the first identified tetraspanins, Tspan8 promotes tumor progression and metastasis, presumably by stimulating angiogenesis and cell motility. In patients, its expression on digestive tract tumors seems to be associated with a bad prognosis. We showed previously that Tspan8 associates with E-cadherin and EGFR and modulates their effects on cell motility. Using Mass spectrometry and western blot, we found a new partner, the endothelin converting enzyme ECE1, and showed that Tspan8 amplifies its activity of conversion of the endothelin-1 precursor bigET1 to endothelin. This was observed by transduction of the colon carcinoma cell line Isreco1, which does not express Tspan8, and on ileum tissue fragments of tspan8ko mice versus wild type mice. Given these results, Tspan8 appears to be a modulator of the endothelin axis, which could possibly be targeted in case of over-activity of endothelins in biological processes of tissues expressing Tspan8.

Insights into Endothelin Receptors in Pulmonary Hypertension

Pulmonary hypertension (PH) is a disease which affects the cardiopulmonary system; it is defined as a mean pulmonary artery pressure (mPAP) > 20 mmHg as measured by right heart catheterization at rest, and is caused by complex and diverse mechanisms. In response to stimuli such as hypoxia and ischemia, the expression and synthesis of endothelin (ET) increase, leading to the activation of various signaling pathways downstream of it and producing effects such as the induction of abnormal vascular proliferation during the development of the disease. This paper reviews the regulation of endothelin receptors and their pathways in normal physiological processes and disease processes, and describes the mechanistic roles of ET receptor antagonists that are currently approved and used in clinical studies. Current clinical researches on ET are focused on the development of multi-target combinations and novel delivery methods to improve efficacy and patient compliance while reducing side effects. In this review, future research directions and trends of ET targets are described, including monotherapy and precision medicine.

The endothelin receptor antagonist macitentan ameliorates endothelin-mediated vasoconstriction and promotes the survival of retinal ganglion cells in rats

Glaucoma is a chronic and progressive eye disease, commonly associated with elevated intraocular pressure (IOP) and characterized by optic nerve degeneration, cupping of the optic disc, and loss of retinal ganglion cells (RGCs). The pathological changes in glaucoma are triggered by multiple mechanisms and both mechanical effects and vascular factors are thought to contribute to the etiology of glaucoma. Various studies have shown that endothelin-1 (ET-1), a vasoactive peptide, acting through its G protein coupled receptors, ETA and ETB, plays a pathophysiologic role in glaucoma. However, the mechanisms by which ET-1 contribute to neurodegeneration remain to be completely understood. Our laboratory and others demonstrated that macitentan (MAC), a pan endothelin receptor antagonist, has neuroprotective effects in rodent models of IOP elevation. The current study aimed to determine if oral administration of a dual endothelin antagonist, macitentan, could promote neuroprotection in an acute model of intravitreal administration of ET-1. We demonstrate that vasoconstriction following the intravitreal administration of ET-1 was attenuated by dietary administration of the ETA/ETB dual receptor antagonist, macitentan (5 mg/kg body weight) in retired breeder Brown Norway rats. ET-1 intravitreal injection produced a 40% loss of RGCs, which was significantly lower in macitentan-treated rats. We also evaluated the expression levels of glial fibrillary acidic protein (GFAP) at 24 h and 7 days post intravitreal administration of ET-1 in Brown Norway rats as well as following ET-1 treatment in cultured human optic nerve head astrocytes. We observed that at the 24 h time point the expression levels of GFAP was upregulated (indicative of glial activation) following intravitreal ET-1 administration in both retina and optic nerve head regions. However, following macitentan administration for 7 days after intravitreal ET-1 administration, we observed an upregulation of GFAP expression, compared to untreated rats injected intravitreally with ET-1 alone. Macitentan treatment in ET-1 administered rats showed protection of RGC somas but was not able to preserve axonal integrity and functionality. The endothelin receptor antagonist, macitentan, has neuroprotective effects in the retinas of Brown Norway rats acting through different mechanisms, including enhancement of RGC survival and reduction of ET-1 mediated vasoconstriction.

Ethacrynic Acid: A Promising Candidate for Drug Repurposing as an Anticancer Agent

Ethacrynic acid (ECA) is a diuretic that inhibits Na-K-2Cl cotransporter (NKCC2) present in the thick ascending loop of Henle and muculo dens and is clinically used for the treatment of edema caused by excessive body fluid. However, its clinical use is limited due to its low bioavailability and side effects, such as liver damage and hearing loss at high doses. Despite this, ECA has recently emerged as a potential anticancer agent through the approach of drug repositioning, with a novel mechanism of action. ECA has been shown to regulate cancer hallmark processes such as proliferation, apoptosis, migration and invasion, angiogenesis, inflammation, energy metabolism, and the increase of inhibitory growth factors through various mechanisms. Additionally, ECA has been used as a scaffold for synthesizing a new material, and various derivatives have been synthesized. This review explores the potential of ECA and its derivatives as anticancer agents, both alone and in combination with adjuvants, by examining their effects on ten hallmarks of cancer and neuronal contribution to cancer. Furthermore, we investigated the trend of synthesis research of a series of ECA derivatives to improve the bioavailability of ECA. This review highlights the importance of ECA research and its potential to provide a cost-effective alternative to new drug discovery and development for cancer treatment.

Endothelin Receptor Antagonists in Kidney Disease

Endothelin (ET) is found to be increased in kidney disease secondary to hyperglycaemia, hypertension, acidosis, and the presence of insulin or proinflammatory cytokines. In this context, ET, via the endothelin receptor type A (ETA) activation, causes sustained vasoconstriction of the afferent arterioles that produces deleterious effects such as hyperfiltration, podocyte damage, proteinuria and, eventually, GFR decline. Therefore, endothelin receptor antagonists (ERAs) have been proposed as a therapeutic strategy to reduce proteinuria and slow the progression of kidney disease. Preclinical and clinical evidence has revealed that the administration of ERAs reduces kidney fibrosis, inflammation and proteinuria. Currently, the efficacy of many ERAs to treat kidney disease is being tested in randomized controlled trials; however, some of these, such as avosentan and atrasentan, were not commercialized due to the adverse events related to their use. Therefore, to take advantage of the protective properties of the ERAs, the use of ETA receptor-specific antagonists and/or combining them with sodium-glucose cotransporter 2 inhibitors (SGLT2i) has been proposed to prevent oedemas, the main ERAs-related deleterious effect. The use of a dual angiotensin-II type 1/endothelin receptor blocker (sparsentan) is also being evaluated to treat kidney disease. Here, we reviewed the main ERAs developed and the preclinical and clinical evidence of their kidney-protective effects. Additionally, we provided an overview of new strategies that have been proposed to integrate ERAs in kidney disease treatment.

Real-world effectiveness and safety of bosentan in Japanese patients with systemic sclerosis: A single-center retrospective study

Patients with systemic sclerosis (SSc) develop various vascular disorders, including digital ulcers (DUs), which are sometimes intractable. Bosentan is a dual endothelin receptor antagonist expected to suppress the development of new DUs. The objective of this study was to analyze retrospectively Japanese SSc patients treated with bosentan and investigate its efficacy and safety. We analyzed 40 patients who visited our department from 2009 to 2022 and were treated with bosentan. Of the 25 patients who were able to continue bosentan, 64% (16 patients) were cured by 16 weeks . New DUs occurred in 5.9% (2/34) of patients and the number of new DUs per person was 0.1. Adverse events occurred in 45% (18/40), and hepatic dysfunction was occurred most frequently at 32.5% (13/40). In univariate analysis, hepatic dysfunction was significantly high in patients with low modified Rodnan total skin thickness score. Antimitochondria-antibody-positive patients were more likely to develop liver dysfunction. Hepatic dysfunction was improved without the reduction or discontinuation, dose reduction, discontinuation, or concomitant use of ursodeoxycholic acid. These results suggest that bosentan can be selected as an additional treatment for DU, which is difficult to treat with existing therapies, while carefully monitoring hepatic function.

Regulatory mechanisms of retinal ganglion cell death in normal tension glaucoma and potential therapies

Normal tension glaucoma (NTG) is a multifactorial optic neuropathy characterized by normal intraocular pressure, progressive retinal ganglion cell (RGC) death, and glaucomatous visual field loss. Recent studies have described the mechanisms underlying the pathogenesis of NTG. In addition to controlling intraocular pressure, neuroprotection and reduction of RGC degeneration may be beneficial therapies for NTG. In this review, we summarized the main regulatory mechanisms of RGC death in NTG, including autophagy, glutamate neurotoxicity, oxidative stress, neuroinflammation, immunity, and vasoconstriction. Autophagy can be induced by retinal hypoxia and axonal damage. In this process, ischemia can cause mutations of optineurin and activate the nuclear factor-kappa B pathway. Glutamate neurotoxicity is induced by the over-stimulation of N-methyl-D-aspartate membrane receptors by glutamate, which occurs in RGCs and induces progressive glaucomatous optic neuropathy. Oxidative stress also participates in NTG-related glaucomatous optic neuropathy. It impairs the mitochondrial and DNA function of RGCs through the apoptosis signal-regulating kinase-JUN N-terminal kinase pathway. Moreover, it increases inflammation and the immune response of RGCs. Endothelin 1 causes endothelial dysfunction and impairment of ocular blood flow, promoting vasospasm and glaucomatous optic neuropathy, as a result of NTG. In conclusion, we discussed research progress on potential options for the protection of RGCs, including TANK binding kinase 1 inhibitors regulating autophagy, N-methyl-D-aspartate receptor antagonists inhibiting glutamate toxicity, ASK1 inhibitors regulating mitochondrial function, and antioxidants inhibiting oxidative stress. In NTG, RGC death is regulated by a network of mechanisms, while various potential targets protect RGCs. Collectively, these findings provide insight into the pathogenesis of NTG and potential therapeutic strategies.

Recent Advances in the Treatment of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a disease in which stenosis or obstruction of the pulmonary arteries (PAs) causes an increase in PA pressure, leading to right-sided heart failure and death. Basic research has revealed a decrease in the levels of endogenous vasodilators, such as prostacyclin, and an increase in the levels of endogenous vasoconstrictors, such as endothelin, in patients with PAH, leading to the development of therapeutic agents. Currently, therapeutic agents for PAH target three pathways that are selective for PAs: the prostacyclin, endothelin, and nitric oxide pathways. These treatments improve the prognosis of PAH patients. In this review, we introduce new drug therapies and provide an overview of the current therapeutic agents.

Colostomy Delays Cell Loss in the Brain and Improves Juvenile Survival in a Neonatal Rat Model of Hirschsprung's Disease

Hirschsprung's disease is a congenital malformation characterized by the absence of enteric ganglia in the distal intestine and gut obstruction. Our previous study indicates the brain pathology during the disease progression. A subpopulation of Hirschsprung's disease patients is also associated with anomalies of the central nervous system. In the investigation, we studied a rat model of Hirschsprung's disease, known as spotting lethal (sl/sl) ETB-/- rats, which carries a spontaneous deletion in endothelin receptor B (human gene name: EDNRB) and manifests a similar phenotype as humans with Hirschsprung's disease. Homozygous mutant sl/sl rats were successfully rescued from premature death by performing colostomy and dramatically survived to their juvenile age. By the body weight measured, their body growth was not revealed to be significantly different between ETB-/- and wildtype ETB+/+ or heterozygous (+/sl) ETB+/- groups while all underwent the same colostomy. Cell loss was investigated in several brain regions by using terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay (TUNEL) in ETB+/+, ETB-/-, and ETB+/- rats. Number of TUNEL-positive cells in the cerebellum and the hippocampus of ETB-/- rats was significantly increased compared with that of the ETB+/+ and ETB+/- rats. TUNEL-positive cells were observed in the molecular layer and granular cell layers of the cerebellum. In contrast, no significant difference in the density of TUNEL-positive cells was revealed in the cerebral cortex. These results suggest that either endothelin receptor B sl mutation or colostomy has predominant lasting effects on the cell survival/loss in the cerebellum and hippocampus of adult ETB-/- rats. Our findings provide the information on cellular changes in the brains of patients with Hirschsprung's disease due to congenital EDNRB mutation as well as clinically relevant interventions.

Induction of reactive oxygen species by mechanical stretch drives endothelin production in neonatal pig renal epithelial cells

Vasoactive endothelin (ET) is generated by ET converting enzyme (ECE)-induced proteolytic processing of pro-molecule big ET to biologically active peptides. H2O2 has been shown to increase the expression of ECE1 via transactivation of its promoter. The present study demonstrates that H2O2 triggered ECE1-dependent ET1-3 production in neonatal pig proximal tubule (PT) epithelial cells. A uniaxial stretch of PT cells decreased catalase, increased NADPH oxidase (NOX)2 and NOX4, and increased H2O2 levels. Stretch also increased cellular ECE1, an effect reversed by EUK-134 (a synthetic superoxide dismutase/catalase mimetic), NOX inhibitor apocynin, and siRNA-mediated knockdown of NOX2 and NOX4. Short-term unilateral ureteral obstruction (UUO), an inducer of renal tubular cell stretch and oxidative stress, increased renal ET1-3 generation and vascular resistance (RVR) in neonatal pigs. Despite removing the obstruction, UUO-induced increase in RVR persisted, resulting in early acute kidney injury (AKI). ET receptor (ETR)-operated Ca2+ entry in renal microvascular smooth muscle (SM) via transient receptor potential channel 3 (TRPC3) channels reduced renal blood flow and increased RVR. Although acute reversible UUO (rUUO) did not change protein expression levels of ETR and TRPC3 in renal microvessels, inhibition of ECE1, ETR, and TRPC3 protected against renal hypoperfusion, RVR increase, and early AKI. These data suggest that mechanical stretch-driven oxyradical generation stimulates ET production in neonatal pig renal epithelial cells. ET activates renal microvascular SM TRPC3, leading to persistent vasoconstriction and reduction in renal blood flow. These mechanisms may underlie rUUO-induced renal insufficiency in infants.

Oral administration of a dual ETA/ETB receptor antagonist promotes neuroprotection in a rodent model of glaucoma

PURPOSE

Glaucoma is a neurodegenerative disease associated with elevated intraocular pressure and characterized by optic nerve axonal degeneration, cupping of the optic disc, and loss of retinal ganglion cells (RGCs). The endothelin (ET) system of vasoactive peptides (ET-1, ET-2, ET-3) and their G-protein coupled receptors (ET_A and ET_B receptors) have been shown to contribute to the pathophysiology of glaucoma. The purpose of this study was to determine whether administration of the endothelin receptor antagonist macitentan was neuroprotective to RGCs and optic nerve axons when administered after the onset of intraocular pressure (IOP) elevation in ocular hypertensive rats.

METHODS

Male and female Brown Norway rats were subjected to the Morrison model of ocular hypertension by injection of hypertonic saline through the episcleral veins. Following IOP elevation, macitentan (5 mg/kg body wt) was administered orally 3 days per week, and rats with IOP elevation were maintained for 4 weeks. RGC function was determined by pattern electroretinography (PERG) at 2 and 4 weeks post-IOP elevation. Rats were euthanized by approved humane methods, and retinal flat mounts were generated and immunostained for the RGC-selective marker Brn3a. PPD-stained optic nerve sections were imaged by confocal microscopy. RGC and axon counts were conducted in a masked manner and compared between the treatment groups.

RESULTS

Significant protection against loss of RGCs and optic nerve axons was found following oral administration of macitentan in rats with elevated IOP. In addition, a protective trend for RGC function, as measured by pattern ERG analysis, was evident following macitentan treatment.

CONCLUSIONS

Macitentan treatment had a neuroprotective effect on RGCs and their axons, independent of its IOP-lowering effect, suggesting that macitentan may complement existing treatments to prevent neurodegeneration during ocular hypertension. The findings presented have implications for the use of macitentan as an oral formulation to promote neuroprotection in glaucoma patients.

Associations of + 138 Ins/del A and + 5665 G/T polymorphisms of endothelin-1 gene with hypertension in Burmese people in Magway, Myanmar

Background

Hypertension is one of the major public health problems worldwide, and is one of the recognized causes of premature deaths every year in the world. The purpose of this study was to investigate the associations between the + 138 insertion/deletion of adenine (Ins/del A) and + 5665 guanine-to-thymine (G/T) polymorphisms of the endothelin-1 gene and hypertension in the residents of Magway Township, Myanmar.

Methods

This study was a cross-sectional comparative study including 60 hypertensive patients and 60 control subjects in Magway Township, Myanmar. The inclusion criterion for hypertension was blood pressure ≥ 140/90 mmHg or previous diagnosis by a physician as hypertension and/or taking antihypertensive drugs. The control group had blood pressure < 140/90 mmHg and no previous diagnosis of hypertension. The genotyping was done by polymerase chain reaction and restriction fragment length polymorphism method.

Results

In this study, the genotype distribution of the + 138 Ins/del A variant was significantly different between hypertensive patients and the control group, especially in the 3A4A genotype (odds ratio [OR], 2.451; 95% confidence interval [CI], 1.138–5.280; P = 0.022). Adenine insertion genotypes (3A4A and 4A4A) were significantly associated with hypertension in the dominant model (OR, 2.494; 95% CI, 1.179–5.276; P = 0.017). In addition, there was a significant association between the 4A allele and hypertension (OR, 1.771; 95% CI, 1.026–3.056; P = 0.040). The genotype and allelic distributions of the + 5665 G/T polymorphism were not significantly different between the hypertensive patients and the control group (P > 0.05). In this study, there was no significant association between the genotype and allele frequency, and hypertension (P > 0.05). The linkage disequilibrium was weak between the + 138 Ins/del A and + 5665 G/T loci (D’ = 0.108, r² = 0.009).

Conclusions

This study provides evidence that the + 138 Ins/del A rather than + 5665 G/T polymorphism is associated with hypertension in Burmese people.

Investigating the specificity of endothelin-traps as a potential therapeutic tool for endothelin-1 related disorders

BACKGROUND

Endothelin (ET)-traps are Fc-fusion proteins with a design based on the physiological receptors of ET-1. Previous work has shown that use of the selected ET-traps potently and significantly reduces different markers of diabetes pathology back to normal, non-disease levels.

AIM

To demonstrate the selected ET-traps potently and significantly bind to ET-1.

METHODS

We performed phage display experiments to test different constructs of ET-traps, and conducted bio-layer interferometry binding assays to verify that the selected ET-traps bind specifically to ET-1 and display binding affinity in the double-digit picomolar range (an average of 73.8 rM, n = 6).

RESULTS

These experiments have confirmed our choice of the final ET-traps and provided proof-of-concept for the potential use of constructs as effective biologics for diseases associated with pathologically elevated ET-1.

CONCLUSION

There is increased need for such therapeutics as they could help save millions of lives around the world.

Mutations in rhodopsin, endothelin B receptor, and CC chemokine receptor 5 in large animals: Modeling human diseases

G protein-coupled receptors (GPCRs) are the largest family of cell membrane receptors involved in modulating almost all physiological processes by transducing extracellular signals into the cytoplasm. Dysfunctions of GPCR-regulated signaling result in diverse human diseases, making GPCRs the most popular drug targets for human medicine. Large animals share higher similarities (in physiology and metabolism) with humans than rodents. Similar to findings in human genetics, diverse diseases caused by mutations in GPCR genes have also been discovered in large animals. Rhodopsin, endothelin B receptor, and CC chemokine receptor type 5 have been shown to be involved in human retinitis pigmentosa, Hirschsprung disease, and HIV infection/AIDS, respectively, and several mutations of these GPCRs have also been identified from large animals. The large animals with naturally occurring mutations of these GPCRs provide an opportunity to gain a better understanding of the pathogenesis of human diseases, and can be used for preclinical trials of therapies for human diseases. In this review, we aim to summarize the naturally occurring mutations of these three GPCRs in large animals and humans.

Endothelin and the Cardiovascular System: The Long Journey and Where We Are Going

Simple Summary

In this review, we describe the basic functions of endothelin and related molecules, including their receptors and enzymes. Furthermore, we discuss the important role of endothelin in several cardiovascular diseases, the relevant clinical evidence for targeting the endothelin pathway, and the scope of endothelin-targeting treatments in the future. We highlight the present uses of endothelin receptor antagonists and the advancements in the development of future treatment options, thereby providing an overview of endothelin research over the years and its future scope.

Abstract

Endothelin was first discovered more than 30 years ago as a potent vasoconstrictor. In subsequent years, three isoforms, two canonical receptors, and two converting enzymes were identified, and their basic functions were elucidated by numerous preclinical and clinical studies. Over the years, the endothelin system has been found to be critical in the pathogenesis of several cardiovascular diseases, including hypertension, pulmonary arterial hypertension, heart failure, and coronary artery disease. In this review, we summarize the current knowledge on endothelin and its role in cardiovascular diseases. Furthermore, we discuss how endothelin-targeting therapies, such as endothelin receptor antagonists, have been employed to treat cardiovascular diseases with varying degrees of success. Lastly, we provide a glimpse of what could be in store for endothelin-targeting treatment options for cardiovascular diseases in the future.

Common Variation in EDN1 Regulatory Regions Highlights the Role of PPARγ as a Key Regulator of Endothelin in vitro

Pulmonary Arterial Hypertension (PAH) is a rare disease caused by the obliteration of the pulmonary arterioles, increasing pulmonary vascular resistance and eventually causing right heart failure. Endothelin-1 (EDN1) is a vasoconstrictor peptide whose levels are indicators of disease progression and its pathway is one of the most common targeted by current treatments. We sequenced the EDN1 untranslated regions of a small subset of patients with PAH, predicted the effect in silico, and used a luciferase assay with the different genotypes to analyze its influence on gene expression. Finally, we used siRNAs against the major transcription factors (TFs) predicted for these regions [peroxisome proliferator-activated receptor γ (PPARγ), Krüppel-Like Factor 4 (KLF4), and vitamin D receptor (VDR)] to assess EDN1 expression in cell culture and validate the binding sites. First, we detected a single nucleotide polymorphism (SNP) in the 5' untranslated region (UTR; rs397751713) and another in the 3'regulatory region (rs2859338) that altered luciferase activity in vitro depending on their genotype. We determined in silico that KLF4/PPARγ could bind to the rs397751713 and VDR to rs2859338. By using siRNAs and luciferase assays, we determined that PPARγ binds differentially to rs397751713. PPARγ and VDR Knock-Down (KD) increased the EDN1 mRNA levels and EDN1 production in porcine aortic endothelial cells (PAECs), while PPARγ and KLF4 KD increased the EDN1 production in HeLa. In conclusion, common variants in EDN1 regulatory regions could alter EDN1 levels. We were able to validate that PPARγ binds in rs397751713 and is a key regulator of EDN1. In addition, KLF4 and VDR regulate EDN1 production in a cell-dependent manner, but VDR does not bind directly to the regions we studied.

Relationship between endothelin and nitric oxide pathways in the onset and maintenance of hypertension in children and adolescents

The mechanisms that regulate blood pressure are numerous and complex; one mechanism that plays an important role in this scenario is represented by the balance between the vasoconstrictor effect of endothelin-1 and the vasodilator effect of nitric oxide. While there is agreement on the fact that increased endothelin-1 activity and decreased nitric oxide bioavailability are present in hypertensive adults, the situation is less clear in children and adolescents. Not all studies agree on the finding of an increase in plasma endothelin-1 levels in hypertensive children and adolescents; in addition, the picture is often confused by the concomitant presence of obesity, a condition that stimulates the production of endothelin-1. Furthermore, there is recent evidence that, in younger obese and hypertensive subjects, there is an overproduction of nitric oxide, rather than a reduction. This condition may change over time, causing endothelial dysfunction due to a reduced availability of nitric oxide in hypertensive adolescents. The purpose of this review is to address the main biochemical and pathophysiological aspects of endothelin and nitric oxide involvement in hypertension and to summarize the available scientific evidence on their role in the onset and maintenance of high blood pressure in children and adolescents.

The Summarized Assessment of Endothelin A Receptor Expression in Renal Transplant Compartments Associated with Antibody-Mediated Rejection

The occurrence of anti-endothelin A receptor antibodies may be useful in diagnosis of transplant damage. We noticed that the presence of the endothelin A receptor (ETA receptor) in biopsy compartments is yet to be defined. We decided therefore to analysed the presence and relevance of the ETA receptor in biopsy to define the cause. Our study aims to evaluate the expression of ETA receptors in renal recipients after a biopsy due to the worsening of transplant function.

METHODS

The expression of ETA receptors was analyzed in renal transplant biopsies using the immunohistochemical method. The evaluation of ETA receptors was performed on paraffin sections. ETA receptor expression was analyzed in four compartments of renal transplant biopsies: glomeruli; vessels; tubular epithelium; and interstitium. The assessment was presented using a three-step scale (0: lack of expression; 1: mild to moderate immunoreactivity; 2: high expression). The results of each compartment from a single biopsy were summarized and assessed in the context of antibody-mediated rejection (AMR).

RESULTS

We analyzed 156 patients who had a renal allograft biopsy after renal transplantation. For each patient, we created a summarized ETA receptor expression score. The summarized ETA receptor expression score analysis showed statistically significant differences in patients with and without AMR. In addition, we noticed that patients with AMR had a significantly higher mean summarized expression of ETA receptor score of 3.28 ± 1.56 compared to patients who had a biopsy for other reasons with a mean summarized ETA receptor expression score of 1.47 ± 1.35 (p < 0.000001). ROC analysis of the ETA receptor expression score for detecting AMR status showed that the most appropriate cut-off for the test of the chosen binary classifier is between 2 and 3 of the summarized ETA receptor expression score.

CONCLUSIONS

The expression of endothelin A receptors in renal transplant compartments may be associated with antibody-mediated rejection. The positive ETA receptor staining might be a vital feature in the diagnosis of damage in AMR. The summarized ETA receptor expression score seems to be an exciting diagnostic tool in transplant injury assessment.

Endothelin-1 RS5370 gene polymorphism in primary nephrotic syndrome: A case-control study

INTRODUCTION

Primary nephrotic syndrome (NS) is a common glomerular disease in children. We assessed the genotypes and frequency of the rs5370 allelic variant of the EDN1 gene in children with primary NS.

PATIENTS AND METHODS

We conducted a case-control study in Mansoura University Children's Hospital, Egypt between December 2015 and January 2018. We recruited 50 patients with steroid-sensitive NS (SSNS) and 50 patients with steroid-resistant NS (SRNS) in addition to 100 healthy controls. The patients underwent clinical evaluations and tests including measurement of serum albumin, cholesterol, creatinine and urea levels and a 24-h urinary protein test. We used polymerase chain reaction methods to assess the genotypes of rs5370 variants of the EDN1 gene (GG, GT and TT) and alleles (T and G) in the groups under study.

RESULTS

The most frequent genotype of the EDN1 gene at the locus of interest in the control group was the GT genotype (88%; P=.001) while the GG genotype was more frequent in the NS group compared to the control group (P=.02). We did not find statistically significant differences between the NS and control groups in regard to the EDN1 rs5370 alleles (P=.69). The GG genotype was more frequent in the SSNS group compared to the SRNS and control groups (P=.03). When we compared allele frequencies between the control, SSNS and SRNS groups, we did not find significant differences (P=.89). The GT genotype was associated with normal blood pressure in children with NS (P=.007), while the GG genotype was associated with hypertension (P<.001). We did not find statistically significant differences in renal histopathology or serum cholesterol levels based on the genotype.

CONCLUSIONS

The GG genotype at the rs5370 locus of the EDN1 gene may be associated with an increased risk of primary NS and a better response to steroid therapy.

The Causal Relationship between Endothelin-1 and Hypertension: Focusing on Endothelial Dysfunction, Arterial Stiffness, Vascular Remodeling, and Blood Pressure Regulation

Hypertension (HTN) is one of the most prevalent diseases worldwide and is among the most important risk factors for cardiovascular and cerebrovascular complications. It is currently thought to be the result of disturbances in a number of neural, renal, hormonal, and vascular mechanisms regulating blood pressure (BP), so crucial importance is given to the imbalance of a number of vasoactive factors produced by the endothelium. Decreased nitric oxide production and increased production of endothelin-1 (ET-1) in the vascular wall may promote oxidative stress and low-grade inflammation, with the development of endothelial dysfunction (ED) and increased vasoconstrictor activity. Increased ET-1 production can contribute to arterial aging and the development of atherosclerotic changes, which are associated with increased arterial stiffness and manifestation of isolated systolic HTN. In addition, ET-1 is involved in the complex regulation of BP through synergistic interactions with angiotensin II, regulates the production of catecholamines and sympathetic activity, affects renal hemodynamics and water–salt balance, and regulates baroreceptor activity and myocardial contractility. This review focuses on the relationship between ET-1 and HTN and in particular on the key role of ET-1 in the pathogenesis of ED, arterial structural changes, and impaired vascular regulation of BP. The information presented includes basic concepts on the role of ET-1 in the pathogenesis of HTN without going into detailed analyses, which allows it to be used by a wide range of specialists. Also, the main pathological processes and mechanisms are richly illustrated for better understanding.

Endothelin-1 axes in the framework of predictive, preventive and personalised (3P) medicine

Endothelin-1 (ET-1) is involved in the regulation of a myriad of processes highly relevant for physical and mental well-being; female and male health; in the modulation of senses, pain, stress reactions and drug sensitivity as well as healing processes, amongst others. Shifted ET-1 homeostasis may influence and predict the development and progression of suboptimal health conditions, metabolic impairments with cascading complications, ageing and related pathologies, cardiovascular diseases, neurodegenerative pathologies, aggressive malignancies, modulating, therefore, individual outcomes of both non-communicable and infectious diseases such as COVID-19. This article provides an in-depth analysis of the involvement of ET-1 and related regulatory pathways in physiological and pathophysiological processes and estimates its capacity as a predictor of ageing and related pathologies,a sensor of lifestyle quality and progression of suboptimal health conditions to diseases for their targeted preventionand as a potent target for cost-effective treatments tailored to the person.

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 (ET_A R) and B (ET_B 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 ET_B R remain intact, whereas activation of the ET_A R depends on the intramolecular ring size. Increasing of the intramolecular ring structure reduces activity at the ET_A R and shifts the peptide toward ET_B R selectivity. All ET-1 analogs displayed efficient ET_B R-mediated signaling by G protein activation and arrestin 3 recruitment. Our study provides in-depth characterization of the ET-1/ET_A R and ET-1/ET_B 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-targeted new treatments for proteinuric and inflammatory glomerular diseases: focus on the added value to anti-renin-angiotensin system inhibition

Chronic kidney disease (CKD) is the main cause of end-stage renal disease worldwide arising as a frequent complication of diabetes, obesity, and hypertension. Current therapeutic options, mainly based of inhibition of the renin-angiotensin system (RAS), provide imperfect renoprotection if started at an advanced phase of the disease, and treatments that show or even reverse the progression of CKD are needed. The endothelin (ET) system contributes to the normal renal physiology; however, robust evidence suggests a key role of ET-1 and its cognate receptors, in the progression of CKD. The effectiveness of ET receptor antagonists in ameliorating renal hemodynamics and fibrosis has been largely demonstrated in different experimental models. A significant antiproteinuric effect of ET receptor antagonists has been found in diabetic and non-diabetic CKD patients even on top of RAS blockade, and emerging evidence from ongoing clinical trials highlights their beneficial effects on a wide range of kidney disorders.

Nanomedicine in the treatment of diabetic nephropathy

Globally, diabetic nephropathy (DN) is the foremost cause of end-stage renal disease. With the incidence of diabetes increasing day by day, DN's occurrence is expected to surge to pandemic proportions. Current available therapeutic interventions associated with DN emphasize blood pressure, glycemia and lipid control while ignoring DN's progression mechanism at a molecular level. This review sheds light on the molecular insights involved in DN to help understand the initiation and progression pattern. Further, we summarize novel strategies with reported applications in developing a nanomedicine-based platform for DN-targeted drug delivery to improve drug efficacy and safety.

Endothelin A Receptors Expressed in Glomeruli of Renal Transplant Patients May Be Associated with Antibody-Mediated Rejection

BACKGROUND

Non-human leukocyte antigen (HLA) anti-endothelin A receptor antibodies are presented as being potentially important, but the expression of the endothelin A receptor in glomeruli (ETA receptor (g+)) has not yet been described. We decided to evaluate the presence and relevance of the ETA receptor in for-cause renal transplant biopsies. The aim of our study was to evaluate the immunoreactivity of the ETA receptor and its significance in patients who underwent a renal transplant biopsy due to the deterioration of transplant function, with detailed characterization of staining in glomeruli.

METHODS

The immunohistochemical expression of ETA receptor (ETAR) was analyzed in renal transplant biopsies. Microscopic evaluation was performed on paraffin sections in glomeruli. The analysis was performed using a two-step scale (0: lack of ETAR expression; 1: the presence of ETAR expression-mild to moderate immunoreactivity).

RESULTS

We analyzed 149 patients who underwent renal allograft biopsy after renal transplantation. Positive staining of ETA receptors in glomeruli (ETA receptor (g+)) was noticed in 13/149 (8.7%) patients. Five of these 13 (38.5%) patients with ETA receptor (g+) developed antibody-mediated rejection (AMR), while 13 of the remaining 136 (9.5%) ETA receptor (g-) patients developed AMR (p = 0.0022). Graft loss was noticed in all but one ETA receptor (g+) patient with AMR (4/5; 80%), but only in 2/13 (15%) ETA receptor (g-) patients with AMR (p = 0.009) during the first year after biopsy.

CONCLUSIONS

The expression of endothelin A receptors in glomeruli seems to be a potentially important feature in the diagnosis of damage during antibody-mediated rejection. It may help to identify patients at a higher risk of allograft rejection and injury.

YAP and endothelin-1 signaling: an emerging alliance in cancer

The rational making the G protein-coupled receptors (GPCR) the centerpiece of targeted therapies is fueled by the awareness that GPCR-initiated signaling acts as pivotal driver of the early stages of progression in a broad landscape of human malignancies. The endothelin-1 (ET-1) receptors (ET-1R), known as ET_A receptor (ET_AR) and ET_B receptor (ET_BR) that belong to the GPCR superfamily, affect both cancer initiation and progression in a variety of cancer types. By the cross-talking with multiple signaling pathways mainly through the scaffold protein β-arrestin1 (β-arr1), ET-1R axis cooperates with an array of molecular determinants, including transcription factors and co-factors, strongly affecting tumor cell fate and behavior. In this scenario, recent findings shed light on the interplay between ET-1 and the Hippo pathway. In ET_AR highly expressing tumors ET-1 axis induces the de-phosphorylation and nuclear accumulation of the Hippo pathway downstream effectors, the paralogous transcriptional cofactors Yes-associated protein (YAP) and Transcriptional coactivator with PDZ-binding motif (TAZ). Recent evidence have discovered that ET-1R/β-arr1 axis instigates a transcriptional interplay involving YAP and mutant p53 proteins, which share a common gene signature and cooperate in a oncogenic signaling network. Mechanistically, YAP and mutp53 are enrolled in nuclear complexes that turn on a highly selective YAP/mutp53-dependent transcriptional response. Notably, ET-1R blockade by the FDA approved dual ET-1 receptor antagonist macitentan interferes with ET-1R/YAP/mutp53 signaling interplay, through the simultaneous suppression of YAP and mutp53 functions, hampering metastasis and therapy resistance. Based on these evidences, we aim to review the recent findings linking the GPCR signaling, as for ET-1R, to YAP/TAZ signaling, underlining the clinical relevance of the blockade of such signaling network in the tumor and microenvironmental contexts. In particular, we debate the clinical implications regarding the use of dual ET-1R antagonists to blunt gain of function activity of mutant p53 proteins and thereby considering them as a potential therapeutic option for mutant p53 cancers. The identification of ET-1R/β-arr1-intertwined and bi-directional signaling pathways as targetable vulnerabilities, may open new therapeutic approaches able to disable the ET-1R-orchestrated YAP/mutp53 signaling network in both tumor and stromal cells and concurrently sensitizes to high-efficacy combined therapeutics.

[Endothelin-1 rs5370 gene polymorphism in primary nephrotic syndrome: A case-control study]

INTRODUCTION

Primary nephrotic syndrome (NS) is a common glomerular disease in children. We assessed the genotypes and frequency of the rs5370 allelic variant of the EDN1 gene in children with primary NS.

PATIENTS AND METHODS

We conducted a case-control study in Mansoura University Children's Hospital, Egypt, between December 2015 and January 2018. We recruited 50 patients with steroid-sensitive NS (SSNS) and 50 patients with steroid-resistant NS (SRNS) in addition to 100 healthy controls. The patients underwent clinical evaluations and tests including measurement of serum albumin, cholesterol, creatinine and urea levels and a 24-hour urinary protein test. We used polymerase chain reaction methods to assess the genotypes of rs5370 variants of the EDN1 gene (GG, GT and TT) and alleles (T and G) in the groups under study.

RESULTS

The most frequent genotype of the EDN1 gene at the locus of interest in the control group was the GT genotype (88%; P=.001) while the GG genotype was more frequent in the NS group compared to the control group (P=.02). We did not find statistically significant differences between the NS and control groups in regard to the EDN1 rs5370 alleles (P=.69). The GG genotype was more frequent in the SSNS group compared to the SRNS and control groups (P=.03). When we compared allele frequencies between the control, SSNS and SRNS groups, we did not find significant differences (P=.89). The GT genotype was associated with normal blood pressure in children with NS (P=.007), while the GG genotype was associated with hypertension (P<.001). We did not find statistically significant differences in renal histopathology or serum cholesterol levels based on the genotype.

CONCLUSIONS

The GG genotype at the rs5370 locus of the EDN1 gene may be associated with an increased risk of primary NS and a better response to steroid therapy.

ETA receptors are involved in the febrile response induced by high dose of bacterial endotoxin

Previous studies have demonstrated that endothelin-1 (ET-1) is involved in the febrile response induced by lipopolysaccharide (LPS) in male and female rats. This peptide induces fever acting on ET_B receptors in the central nervous system. However, during sepsis, endothelinergic ET_A receptors in the brain also exert an important role reducing the mortality of the animals. The present study evaluated the participation of ET_A receptors in the febrile response induced by different doses LPS in rats. Male Wistar rats were treated with the ET_A receptor antagonist BQ123 before or after the injection of a low dose (10 μg/kg) or a high dose (200 μg/kg) of LPS intraperitoneally. The febrile response was evaluated. The treatment with BQ123, in both protocols did not change the febrile response induced by the lower dose of LPS. The pre-treatment with BQ123 also did not significantly change the febrile response induced by a higher dose of LPS but the post-treatment with the antagonist abolished the febrile response induced by this dose of LPS. These results suggest that even though ET_A receptors are not recruited in the febrile response induced by lower doses of LPS, they are involved in the febrile response induced by high doses of this stimulus.

Endothelin-1 in the pathophysiology of obesity and insulin resistance

The association between plasma endothelin-1 (ET-1) and obesity has been documented for decades, yet the contribution of ET-1 to risk factors associated with obesity is not fully understood. In 1994, one of first papers to document this association also noted a positive correlation between plasma insulin and ET-1, suggesting a potential contribution of ET-1 to the development of insulin resistance. Both endogenous receptors for ET-1, ETA and ETB are present in all insulin-sensitive tissues including adipose, liver and muscle, and ET-1 actions within these tissues suggest that ET-1 may be playing a role in the pathogenesis of insulin resistance. Further, antagonists for ET-1 receptors are clinically approved making these sites attractive therapeutic targets. This review focuses on known mechanisms through which ET-1 affects plasma lipid profiles and insulin signalling in these metabolically important tissues and also identifies gaps in our understanding of ET-1 in obesity-related pathophysiology.

Sirtuin-1 inhibits endothelin-2 expression in human granulosa-lutein cells via hypoxia inducible factor 1 alpha and epigenetic modifications†

Endothelin-2 (EDN2) expression in granulosa cells was previously shown to be highly dependent on the hypoxic mediator, hypoxia inducible factor 1 alpha (HIF1A). Here, we investigated whether sirtuin-1 (SIRT1), by deacetylating HIF1A and class III histones, modulates EDN2 in human granulosa-lutein cells (hGLCs). We found that HIF1A was markedly suppressed in the presence of resveratrol or a specific SIRT1 activator, SRT2104. In turn, hypoxia reduced SIRT1 levels, implying a mutually inhibitory interaction between hypoxia (HIF1A) and SIRT1. Consistent with reduced HIF1A transcriptional activity, SIRT1 activators, resveratrol, SRT2104, and metformin, each acting via different mechanisms, significantly inhibited EDN2. In support, knockdown of SIRT1 with siRNA markedly elevated EDN2, whereas adding SRT2104 to SIRT1-silenced cells abolished the stimulatory effect of siSIRT1 on EDN2 levels further demonstrating that EDN2 is negatively correlated with SIRT1. Next, we investigated whether SIRT1 can also mediate the repression of the EDN2 promoter via histone modification. Chromatin immunoprecipitation (ChIP) analysis revealed that SIRT1 is indeed bound to the EDN2 promoter and that elevated SIRT1 induced a 40% decrease in the acetylation of histone H3, suggesting that SIRT1 inhibits EDN2 promoter activity by inducing a repressive histone configuration. Importantly, SIRT1 activation, using SRT2104 or resveratrol, decreased the viable numbers of hGLC, and silencing SIRT1 enhanced hGLC viability. This effect may be mediated by reducing HIF1A and EDN2 levels, shown to promote cell survival. Taken together, these findings propose novel, physiologically relevant roles for SIRT1 in downregulating EDN2 and survival of hGLCs.

Effects of Psychological Stress on Vascular Physiology: Beyond the Current Imaging Signal

PURPOSE OF REVIEW

This review describes the effects of psychological stress on the physiology of the entire vascular system, from individual cellular components to macrovascular and microvascular responses, and highlights the importance of the vascular system in the context of current limitations in cardiac imaging for evaluation of the cardiovascular response to mental stress.

RECENT FINDINGS

The physiological responses that mediate vascular changes are based on evolutionary needs, but there is increasing evidence that the long-term consequences of psychological stress can precipitate the development and progression of cardiovascular disease (CVD). While there is an extensive body of literature describing localized physiological responses or overt cardiovascular manifestations, often framed within the organ-specific scope of cardiovascular imaging, there has not been a comprehensive description of the global vascular effects of psychological stress. Given the global nature of these processes, targeted cardiovascular imaging modalities may be insufficient. Here we approach the vascular response to mental stress systematically, describing the effects on the endothelium, vascular smooth muscle, and adventitia. We then address the mental stress effects on large vessels and the microvascular compartment, with a discussion of the role of microvascular resistance in the pathophysiology of mental stress-induced myocardial ischemia. Vascular responses to psychological stress involve complex physiological processes that are not fully characterized by routine cardiovascular imaging assessments. Future research incorporating standardized psychological assessments targeted toward vascular mechanisms of stress responses is required to guide the development of behavioral and therapeutic interventions.

Prognostic values of EDNRB in triple-negative breast cancer

Triple-negative breast cancer (TNBC) has a high degree of malignancy. The endothelin B receptor (EDNRB) serves an important role in the occurrence and development of cancer. The present study aimed to investigate the prognostic value of EDNRB in TNBC. A total of 99 cases of TNBC were collected from the Henan Cancer Hospital database and 159 cases of TNBC were collected from The Cancer Genome Atlas database. A χ² test was used to analyze the association between EDNRB and clinicopathological data. Kaplan-Meier analysis and multivariate Cox regression analysis were used to analyze the association between EDNRB and prognosis, and to establish two models. The discrimination degree of the models was evaluated using time-dependent receiver operating characteristic curves and concordance index (C-index), whereas the accuracy and net benefit of the models were evaluated using integrated discriminant improvement (IDI) and decision curves. EDNRB expression was low in TNBC samples (P<0.01). Age (P=0.01), tumor size (P=0.04) and N stage (P=0.01) were associated with EDNRB expression. EDNRB expression was positively associated with stromal score (P<0.01), but not immune score. High expression levels of EDNRB indicated favorable disease-free survival time (hazard ratio, 0.38; 95% CI, 0.15–0.98; P=0.04). The integrated area under the curve and C-index of the new model were increased compared with the old model following the addition of EDNRB expression as a parameter. The IDI values for prediction of the 3- and 5-year survival rates were 0.04 (P=0.02) and 0.05 (P=0.01), respectively. The results of decision curve analysis showed that the new model had higher clinical net benefit than the old model in the range of 3-year survival rate <0.52. In conclusion, EDNRB was associated with a favorable prognosis in patients with TNBC, and may be used as a novel prognostic biomarker.

Influence of Macitentan on the Vascular Tone and Recruitment of Finger Capillaries Under Hypobaric Hypoxia in High Altitude

Betge, Stefan, Stefan Drinda, Thomas Neumann, Laura Bäz, Alexander Pfeil, Christian Schulze, Ralf Mrowka, Christian Jung, and Marcus Franz. Influence of macitentan on the vascular tone and recruitment of finger capillaries under hypobaric hypoxia in high altitude. High Alt Med Biol. 21:336-345, 2020. Introduction: Acute normobaric (NH) and hypobaric hypoxia (HH) has effects on the vascular tone of larger arteries and may have effects on the microcirculation. These effects may be noninvasively detectable by automated devices. A part of these effects may be mediated by endothelin (ET) and should be influenced by macitentan (MAC), a dual endothelin receptor antagonist (ERA). Methods: We used photoplethysmographic sensors, fingertip volume sensors, nailfold capillaroscopy, and laser Doppler probes at rest and after a 5-minute forearm ischemia in healthy study subjects under NH, under HH, and under HH plus a single dose of MAC. Results: NH at simulated 4000 m led to increased heart rates (HR) and pulse wave velocities (PWV) and reduced augmentation index (AIX). The values for the AIX showed a high SD and differed between the used devices. At simulated 5500 m, only baseline mean value (BMV; EndoPAT) showed a further change, indicating less filled capillaries of the fingertips. HH (2978 m) increased HR, blood pressure values, and PWV. Focusing on the microcirculation of the fingertips, HH reduced the BMV and the nailfold capillary density and the postischemic capillary recruitment. MAC had no effect on the BMV, but antagonized the effects of HH on the nailfold capillaries and led to a strongly increased postischemic diameter of the arterial limbs. Concordantly, the postischemic blood flow velocity increment, measured through ultrasound Doppler, was increased at ALT+MAC. Conclusions: The BMV may be a parameter for changes of the microcirculation of the finger tips. A single dose of MAC blocked hypoxia-induced capillary rarefaction and enhanced postischemic hyperemia of the fingertips. These results indicate the importance of ET-1 for the regulation of the microcirculation under hypoxia. The German Registry of Clinical Studies (DRKS) ID: 00005459.

The Clinical Efficacy of Endothelin Receptor Antagonists in Patients with Pulmonary Arterial Hypertension

Therapeutic strategies for pulmonary arterial hypertension (PAH) have made remarkable progress over the last two decades. Currently, 3 types of drugs can be used to treat PAH; prostacyclins, phosphodiesterase 5 inhibitors, and endothelin receptor antagonists (ERA). In Japan, the first generation ERA bosentan was reimbursed in 2005, following which the 2nd generation ERAs ambrisentan and macitentan were reimbursed in 2009 and 2015, respectively. The efficacy of each ERA on hemodynamics in PAH patients remains to be elucidated. The aims of this study were to evaluate the hemodynamic effects of ERAs and compare these effects among each generation of ERAs.We retrospectively examined the clinical parameters of 42 PAH patients who were prescribed an ERA (15 bosentan, 12 ambrisentan, and 15 macitentan) and who underwent a hemodynamic examination before and after ERA introduction at our institution from January 2007 to July 2019.In a total of 42 patients, mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance (PVR) were significantly decreased and cardiac index was significantly increased after ERA introduction (P < 0.001) and the World Health Organization-Functional class (WHO-Fc) was significantly improved after ERA introduction (P = 0.005). Next, in a comparison between 1st and 2nd generation ERAs, 2nd generation ERAs were found to have brought about greater improvements in hemodynamic parameters (mPAP and PVR. P < 0.01), heart rate, brain natriuretic peptide, arterial oxygen saturation, and mixed venous oxygen saturation than the 1st generation ERA bosentan.We conclude that all ERAs could successfully improve the hemodynamics of PAH patients and that the newer generation ERAs, ambrisentan and macitentan, seemed to be preferable to bosentan.

Pathophysiological effects of androgens on the female vascular system

Sex hormones and their respective receptors affect vascular function differently in men and women, so it is reasonable to assume they play a role in the sex differences in cardiovascular disease states. This review focuses on how the effects of testosterone on arterial vessels impact the female vasculature. In women with androgen-excess polycystic ovary syndrome, and in transgender men, testosterone exposure is associated with high blood pressure, endothelial dysfunction, and dyslipidemia. These relationships suggest that androgens may exert pathophysiological effects on the female vasculature, and these effects on the female vasculature appear to be independent from other co-morbidities of cardiovascular disease. There is evidence that the engagement of androgens with androgen receptor induces detrimental outcomes in the female cardiovascular system, thereby representing a potential causative link with sex differences and cardiovascular regulation. Gender affirming hormone therapy is the primary medical intervention sought by transgender people to reduce the characteristics of their natal sex and induce those of their desired sex. Transgender men, and women with androgen-excess polycystic ovary syndrome both represent patient groups that experience chronic hyperandrogenism and thus lifelong exposure to significant medical risk. The study of testosterone effects on the female vasculature is relatively new, and a complex picture has begun to emerge. Long-term research in this area is needed for the development of more consistent models and controlled experimental designs that will provide insights into the impact of endogenous androgen concentrations, testosterone doses for hormone therapy, and specific hormone types on function of the female cardiovascular system.