Endothelin Receptor Research Articles

Endothelin receptor antagonists in chronic kidney disease.

Endothelin-1 is a potent vasoconstrictor that has diverse physiological functions in the kidney, including in the regulation of blood flow and glomerular filtration, electrolyte homeostasis and endothelial function. Overexpression of endothelin-1 contributes to the pathophysiology of both diabetic and non-diabetic chronic kidney disease (CKD). Selective endothelin receptor antagonists (ERAs) that target the endothelin A (ETA) receptor have demonstrated benefits in animal models of kidney disease and in clinical trials. In patients with type 2 diabetes and CKD, the selective ETA ERA, atrasentan, reduced albuminuria and kidney function decline. Concerns about the increased risks of fluid retention and heart failure with ERA use have led to the design of further trials to optimize dosing and patient selection. More recent studies have shown that the dual ETAreceptor andangiotensin receptor blocker, sparsentan, preserved kidney function with minimal fluid retention in patients with IgA nephropathy. Moreover, combined administration of a low dose of the ETA-selective ERA, zibotentan, with the sodium-glucose cotransporter 2 (SGLT2) inhibitor, dapagliflozin, enhanced albuminuria reduction and mitigated fluid retention in patients with CKD. Notably, sparsentan and aprocitentan have received FDA approval for the treatment of IgA nephropathy and treatment-resistant hypertension, respectively. This Review describes our current understanding of the use of ERAs in patients with CKD to guide their optimal safe and effective use in clinical practice.

Double-blinded, randomized tolerance study of a biologically enhanced Nanogel with endothelin-1 and bradykinin receptor antagonist peptides via intra-articular injection for osteoarthritis treatment in horses

BackgroundOsteoarthritis is a leading cause of pain and retirement in athletic horses. Hydro-expansive functionalized nanogels, acting as Drug Delivery Systems, constitute one of the current therapeutic prospects. These nanogels have the potential to combine mechanical benefits through polymers with the biological effect of prolonged release of bioactive molecules. The purpose of this double-blinded randomized tolerance study versus negative control was to evaluate the response of healthy joints to a single injection of the expected efficient dose (further referred to as the trial dose) and overdose of nanogels composed of chitosan and hyaluronic acid and featuring a type A endothelin receptor antagonist and a type B1 bradykinin receptor antagonist. The metacarpophalangeal joints of 8 healthy horses were randomly injected with 2.4 mL of functionalized nanogels and 2.4 mL of saline as control on the contralateral limb. Injections were repeated twice at one-week intervals, followed by injection of a triple dose of nanogel on week four. Clinical, ultrasonographic and synovial fluid cellular and biochemical follow-ups were performed up to three months following the first injection.ResultsNo change in general clinical parameters, lameness or sensitivity to passive flexion of the fetlocks was noted. Mild to moderate synovitis was noted on the day following injection in the treated group, with a significant difference (p < 0.05) compared to the control group. It spontaneously resolved on day 3 following the injections and did not increase with repeated injections. Similar effects were noted after injection of the triple dose but lasted for a week. Synovial fluid markers of inflammation also showed a transient significant increase in the treated group one week after each injection, but no differences were detected at the end of the study.ConclusionsInjections of the expected therapeutic dose of functionalized nanogel in healthy joints induced a mild transient inflammatory response in the joint. Three injections of the trial dose at one-week intervals and injection of thrice the trial dose induce a mildly greater inflammation without harmful effects on joints. Functionalized nanogels are well tolerated prospects for the treatment of osteoarthritis in horses. Their beneficial effects on arthritic joints have yet to be evaluated to determine their therapeutic potential.

Risk of respiratory, thoracic, and mediastinal disorders associated with endothelin receptor antagonists and prostacyclin-related drugs in pulmonary hypertension: a disproportionality analysis based on FAERS

ABSTRACT Background Adverse drug events (ADEs) for endothelin receptor antagonists (ERAs) and prostacyclin-related drugs (PRDs) have been reported in clinical trials, but large-scale, real-world evaluations for respiratory, thoracic, and mediastinal disorders (RTMD) remain scarce. Methods A pharmacovigilance analysis of the FAERS database (Q1 2004~Q2 2024) used the reporting odds ratio (ROR) method for disproportionality analysis to assess the adverse drug events (ADEs) of ERAs and PRDs in pulmonary arterial hypertension, focusing on risks related to RTMD. Results Reports of ADEs for ERAs (bosentan, ambrisentan, and macitentan) were 15,286, 36795, and 17,497, respectively, and for PRDs (epoprostenol, treprostinil, iloprost, and selexipag) were 5,477, 57265, 3,247, and 5,504. Females exceeded males, with most cases in adults. The top PTs for ERAs were death, dyspnea, and pneumonia, with bosentan linked to liver impairment. PRDs commonly cause headaches, flushing, hypotension, edema, and fluid retention. Dyspnea was the most reported RTMD risk for all drugs, and nasal congestion was noted for all. Selexipag had the fewest RTMD-related PTs, and iloprost had the strongest signal for hemoptysis. Conclusion The analysis highlights the RTMD risks of ERAs and PRDs in treating PH and underscores the need for careful monitoring of ADEs to ensure their safe and effective use in clinical practice.

Kinetics of endothelin-1 and effect selective ETA antagonism on ETB activation: a mathematical modeling analysis

IntroductionEndothelin-1 (ET-1) regulates renal and vascular function, but the clinical utility of selective ETA receptor antagonists has been limited due to associated fluid retention. The mechanisms underlying fluid retention remain poorly understood but could be a consequence of changes in ET-1 binding to the unantagonized ETB receptor, either through increased ET-1 or non-selective ETB.MethodsA mathematical model of ET-1 kinetics was developed to quantify effects of ETA antagonist exposure and selectivity on concentrations of ET-1 and its complexes with ETA and ETB receptors. The model describes ET-1 production, tissue and plasma distribution, ETA and ETB receptor binding, and receptor-mediated clearance, and was calibrated and validated with human ET-1 infusion studies.ResultsThe model confirmed the significant role of ETB in ET-1 clearance. By varying both drug ETA selectivity (Kib/Kia) and concentration over a wide range, simulations predicted that while selective ETA antagonist (selectivity &amp;gt;1) always decreased [ET1-ETA], the change in [ET1-ETB] was more complex. It increased up to 45% as drug concentrations approached and exceeded Kia, but the increase was diminished as drug concentration increased further and fell below baseline at high concentrations. The drug concentration required to cause a decrease in [ET1-ETB] was lower as ETA selectivity decreased.DiscussionThis is the first mechanistic mathematical model of ET-1 kinetics that describes receptor-mediated clearance, and the consequence of ETB blockade on ET-1 concentrations. It provides a useful tool that can coupled with experimental studies to quantitively understand and investigate this complex and dynamic system.

Eisenmenger Syndrome: Pathophysiology, Clinical Manifestations, and Contemporary Management Approaches in Advanced Cardiopulmonary Disease

Eisenmenger syndrome, a complex and severe form of congenital heart disease, results from prolonged left-to-right shunting due to underlying cardiac defects such as ventricular septal defects, atrial septal defects, or patent ductus arteriosus, ultimately leading to irreversible pulmonary arterial hypertension and a reversal of the initial shunt. This syndrome represents the most severe spectrum of pulmonary vascular disease associated with congenital heart defects and is characterized by hypoxemia, erythrocytosis, and systemic cyanosis. Despite advances in early diagnosis and intervention in congenital heart disease, Eisenmenger syndrome remains a significant concern due to the irreversible nature of pulmonary vascular changes and associated multisystem complications. This article provides a comprehensive review of the pathophysiology, clinical manifestations, and the role of pharmacologic and non-pharmacologic therapies, including advanced palliative care, to improve patient quality of life. Emerging therapies such as endothelin receptor antagonists, phosphodiesterase-5 inhibitors, and prostacyclin analogs show promise in symptom management, though surgical interventions, such as heart-lung transplantation, remain reserved for selected cases. Given the high mortality associated with Eisenmenger syndrome, a multidisciplinary approach is critical in managing complications, improving patient outcomes, and supporting functional status.

C-C motif chemokine receptor-2 blockade ameliorates pulmonary hypertension in rats and synergizes with a pulmonary vasodilator

Abstract Aims We investigated whether the disruption of C-C motif chemokine receptor (CCR) 2 may attenuate the development of pulmonary arterial hypertension (PAH) in any rat models with the reversal of the associated pro-inflammatory state and vascular dysfunction, and synergize with a conventional pulmonary vasodilator. Methods and Results Using Ccr2(-/-) rats generated by CRISPR/Cas9, we investigated pulmonary hypertension (PH) in Ccr2(+/+) or Ccr2(-/-) rats treated with monocrotaline (MCT), SU5416/hypoxia (SuHx) and chronic hypoxia (CH). Ccr2(-/-) decreased the right ventricular systolic pressure, an index of right ventricular hypertrophy and mortality rate, and reversed increased expression of inflammatory cytokines/chemokines (interleukin-6, tumor necrosis factor-α, C-C motif chemokine receptor (CCL)-2, interleukin-1β, transforming growth factor-β) in rats 3weeks after MCT injection, but not in SuHx or CH models. Consistently, Ccr2(-/-) decreased indices of pulmonary vascular diseases (PVD) and perivascular macrophage infiltration, as well as reversed impaired bone morphogenetic protein receptor type 2 signaling, increased endothelial apoptosis and impaired nitric oxide signaling and decreased phosphodiesterase-5 (PDE5) expression in lungs in MCT-treated rats. Gene expression of receptors for prostaglandin I2 and endothelin was not changed by Ccr2(-/-) in MCT-treated rats. In cultured pulmonary arterial smooth muscle cells (PASMCs), Ccr2(-/-) suppressed CCL2-induced hyperproliferation and dedifferentiation as well as reversed CCL2-induced decrease in PDE5 expression. The whole-genome RNA sequencing analysis identified differentially expressed genes in CCL2-stimulated Ccr2(-/-) PASMCs, which are related to regulation of cellular differentiation and contraction. Based on studies in rats and cultured PASMCs, we investigated whether a PDE5 inhibitor, tadalafil, synergizes with Ccr2(-/-). Tadalafil administration ameliorated PH and PVDs in MCT-treated Ccr2(-/-) rats but not in Ccr2(+/+) rats. Tadalafil further improved survival in MCT-treated Ccr2(-/-) rats. Conclusion The present findings demonstrated that CCR2 disruption ameliorated PAH in MCT-treated rats, which was associated with the reversal of dysregulated inflammatory pathways and vascular dysfunction and synergized with tadalafil. These findings suggest that CCR2 may be a therapeutic target in intractable PAH patients with a certain CCR2-related inflammatory phenotype and refractory to conventional pulmonary vasodilators.

Exploring the Endothelin-1 pathway in chronic thromboembolic pulmonary hypertension microvasculopathy.

Targeted vasopeptide therapies have significantly advanced the management of pulmonary arterial hypertension (PAH). However, due to insufficient preclinical evidence regarding the involvement of the endothelin-1 (ET-1) pathway in chronic thromboembolic pulmonary hypertension (CTEPH) pathophysiology, the potential of ET-1 receptor antagonism in treating CTEPH remains uncertain. In this study, we investigated the role of the ET-1 pathway in CTEPH microvasculopathy using a multifaceted approach. Plasma ET-1 levels were measured in a cohort of 59 CTEPH patients and 41 healthy controls. Additionally, we evaluated the expression of key ET-1 pathway members in pulmonary explants from CTEPH, idiopathic PAH, and control patients. We used an in vitro system to test the hypothesis that the turbulent flow, observed near the vascular obstructions pathognomonic of CTEPH, enhances ET-1 expression. Our findings were further validated in vivo using a CTEPH piglet model that contains distinct regions representing pre- and post-thrombus lung territories. We found a twofold increase in circulating ET-1 levels in CTEPH patients compared to healthy subjects. Pulmonary explants from CTEPH patients exhibited pronounced overexpression of ET-1, endothelin receptor A (ETA), and phosphorylated myosin light chain (p-MLC) in muscularized pulmonary microvessels, suggesting heightened vascular contraction. In vitro experiments showed that turbulent flow facilitates ET-1 secretion compared to laminar flow regions. Additionally, in the CTEPH piglet model, elevated plasma ET-1 levels were observed compared to controls. Immunofluorescence and confocal microscopy analyses confirmed increased ETA and p-MLC in remodeled arteries from both pulmonary territories. However, ET-1 protein elevation was exclusively observed in the obstructed territory. These findings collectively indicate impaired vascular tone in microvessels of CTEPH patients and the CTEPH piglet model. Furthermore, our data implicates the ET-1 pathway in microvasculopathy, with turbulent flow playing a pathological role. These insights underscore the potential utility of ET-1 receptor antagonists as a promising therapeutic approach for CTEPH treatment.

Endothelin-1 receptor blockade impairs invasion patterns in engineered 3D high-grade serous ovarian cancer tumouroids.

High-grade serous ovarian cancer (HG-SOC), accounting for 70-80% of ovarian cancer deaths, is characterized by a widespread and rapid metastatic nature, influenced by diverse cell types, cell-cell interactions, and acellular components of the tumour microenvironment (TME). Within this tumour type, autocrine and paracrine activation of the endothelin-1 receptors (ET-1R), expressed in tumour cells and stromal elements, drives metastatic progression. The lack of three-dimensional models that faithfully recapitulate the unique HG-SOC TME has been the bottleneck in performing drug screening for personalized medicine. Herein, we developed HG-SOC tumouroids by engineering a dense central artificial cancer mass (ACM) containing HG-SOC cells, nested within a compressed hydrogel recapitulating the stromal compartment comprising type I collagen, laminin, fibronectin, and stromal cells (fibroblasts and endothelial cells). ET-1-stimulated HG-SOC cells in the tumouroids showed an altered migration pattern and formed cellular aggregates, mimicking micrometastases that invaded the stroma. Compared with control cells, ET-1-stimulated tumouroids showed a higher number of invasive bodies, which were reduced by treatment with the dual ET-1 receptor (ET-1R) antagonist macitentan. In addition, ET-1 increased the size of the invading aggregates compared with control cells. This study establishes an experimental 3D multicellular model eligible for mechanical research, investigating the impact of matrix stiffness and TME interactions, which will aid drug screening to guide therapeutic decisions in HG-SOC patients.

Abstract 4134327: Efficacy and safety of aprocitentan in patients with resistant hypertension receiving at least 4 antihypertensive medications including beta (β) blockers

Background: Aprocitentan, a dual ET A /ET B endothelin receptor antagonist, was recently FDA-approved for use in combination with other drugs for the treatment of hypertension not adequately controlled on other antihypertensive drugs. β-blockers are used for the prevention of cardiovascular events and have antihypertensive effects. All subjects in the PRECISION study were hypertensive at screening despite receiving ≥3 antihypertensives, with 63.5% on ≥4 and 16.8% on ≥5 antihypertensives. All were switched to a standardized fixed dose triple combination of amlodipine/valsartan/hydrochlorothiazide; and the 456 patients (62.5% of the 730 total) who were on β-blockers at screening continued throughout the study as well. Of these, 173 (37.9%) had a history of ischemic heart disease and 106 (23.2%) a history of congestive heart failure, vs 52 (19%) and 37 (13.5%) not receiving β-blockers. This preplanned subgroup analysis assessed the efficacy and safety of aprocitentan in patients with resistant hypertension on the triple combination with or without β-blockers. Methods: Changes from baseline (BL) in office systolic blood pressure (SBP) and diastolic BP (DBP) were assessed at Week 4, the end of the double-blind treatment phase with aprocitentan 12.5 mg or 25 mg per day or placebo, and at Week 36, at the end of the single-blind aprocitentan 25 mg treatment phase. Results: There was no difference in the efficacy of aprocitentan when patients were on a β-blocker or not. In patients on β-blockers, 12.5 mg and 25 mg aprocitentan decreased SBP from BL to Week 4 by mean -14.9 mmHg and -14.9 mmHg, respectively, vs -11.2 mmHg in the placebo group; and in patients without β-blockers by -16.5 mmHg and -14.9 mmHg vs -11.8 mmHg. Similar results were seen at Week 36, as compared with BL for both subgroups, and at Week 4 for DBP (Table 1). In patients on β-blockers, the incidence of edema/fluid retention at Week 4 was 9.9%, 19.3% and 2.8% in the aprocitentan 12.5 mg, 25 mg and placebo groups, respectively, as compared with 7.6%, 16.7%, and 1.0% in patients without β-blockers. In both subgroups, most events occurred during the first 8 weeks of treatment. The incidence of edema/fluid retention with aprocitentan was comparable with that of the placebo group in both subgroups thereafter. Conclusions: Aprocitentan is effective in lowering BP and has a good safety and tolerability profile in patients with resistant hypertension who are taking 4 or more antihypertensive drugs including β-blockers.

Abstract 4119891: Risk Factors of Anemia in Pulmonary Arterial Hypertension Patients with Endothelin Receptor Antagonists Administration and Related Treatment

Background: Endothelin receptor antagonists (ERAs) demonstrated significant efficiency in delaying clinical deterioration and improving survival of patients with pulmonary arterial hypertension (PAH). However, the frequent occurrence of anemia after ERAs administration has gained clinical attention currently, whereas the etiology of anemia is unclear. The risk factors of ERAs associated anemia remained undefined. Therefore, we aim to investigate risk factors of developing anemia after ERAs treatment and whether iron supplement could correct anemia. Method: A retrospective cohort study was performed among patients with PAH who received ERAs between January, 2017 and December, 2019 in Fuwai hospital. The primary outcome was development of anemia after ERAs therapy and secondary outcome was correction of anemia after iron supplement. Results: A total of 120 patients with PAH were included in the study and 28 patients developed anemia during follow up . Distinctively, all the patients who developed anemia were female. After ERAs administration, iron metabolism (Ferritin 95.29±144.79 μg/L versus 69.9±118.25 μg/L, P &lt;0.001) and hemoglobin (154.21±23.80 g/L versus 136.12±28.61 g/L, P &lt;0.001) reduced significantly in the total cohort with patients who developed anemia more significant. Baseline iron metabolism (Ferritin: HR 0.98, 95%CI 0.96-0.99, P =0.02) was independently associated with development of anemia after ERAs administration. Compared with patients with iron replete, patients with iron deficiency had over 9-fold risk of developing anemia after receiving ERAs (HR = 9.59, 95%CI 3.62-25.41, P &lt; 0.01). Iron supplement could effectively correct anemia. Conclusion: It is advised that patients receiving ERAs monitor iron metabolism and hemoglobin regularly, especially females and those with low hemoglobin level and compromised iron homeostasis before ERAs administration, which facilitates prevention and early detection of anemia. ERAs-related anemia is mostly mild, oral iron supplement could effectively reverse anemia and aberrant iron metabolism.

Abstract 4144559: Sex Differences in Vascular Remodeling in Pulmonary Hypertension are mediated by Endothelin-2

Pulmonary arterial hypertension (PAH) is characterized by pulmonary arterial vascular remodelingleading to increased pulmonary artery pressure causing right ventricular hypertrophy, failure anddeath. The incidence of PAH is much higher in female patients, indicating that males may have aprotective factor that could help elucidate the pathogenesis of PAH. We have recently demonstratedthat the Y chromosome gene UTY protects against PH development in mice, however the fulldownstream mechanisms remains unknown. By integrating RNA-Seq on whole lung tissues fromUty-KO and WT male mice with a publically available male and female PAH lung microarraydataset, we found increased expression of Endothelin 2 (ET-2) in the lungs of Uty-KO compared toWT mice with PH as well as in the lungs of female patients compared to males with PAH. The roleof ET-1 is known in PAH, and Endothelin receptor antagonists are a common PAH therapy to whichfemale patients are more responsive. However, ET-2 has yet to be investigated in this context. Wevalidated that ET-2 expression is significantly increased in lung tissue from PAH female patientscompared to males. Plasma ET-2 concentration is also significantly higher in PAH patients versuscontrols. Interestingly, plasma ET-2 negatively correlates with pulmonary vascular resistance (PVR)and mean pulmonary arterial pressure (mPAP) in male PAH patients, whereas plasma ET-2significantly positively correlates with PVR and mPAP in female PAH patients. Functionally, wefound that recombinant ET-2 significantly inhibits proliferation of male pulmonary artery endothelialcells (PAECs), but significantly promotes proliferation in female PAECs. Similarly, ET-2 significantlyincreased proliferation of female pulmonary artery smooth muscle cells (PASMC), but not malePASMC. Together, we show that increased ET-2 expression may contribute to worsening PH bypromoting vascular remodeling in the lung and that elevated ET2 in females may at least partiallyexplain the higher incidence of female PAH patients

Enhanced Vasoconstriction in Sickle Cell Disease is Dependent on ETA Receptor Activation.

Sickle Cell Disease (SCD) carries a significant risk for poor vascular health and vascular dysfunction. High levels of vascular reactive oxygen species (ROS) as well as elevated plasma endothelin-1 (ET-1), a potent vasoconstrictor with actions via the ETA receptor, are both common phenotypes in SCD. Alpha-1 adrenergic receptor activation is a major mediator of stress-induced vasoconstriction. However, the mechanism of the SCD enhanced vasoconstrictive response is unknown. We hypothesized that SCD induces enhanced alpha-1 adrenergic mediated vasoconstriction through the ET-1/ETA receptor pathway in arterial tissues. Utilizing humanized SCD (HbSS) and genetic control (HbAA) mice, alpha-1a, but not alpha-1b or alpha-1d, receptor expression was significantly greater in aortic tissue from HbSS mice compared to HbAA mice. Significantly enhanced vasoconstriction in aortic and carotid arterial segments were observed from HbSS mice compared to HbAA mice. Treatment with ambrisentan, a selective ETA receptor antagonist, and a ROS scavenger normalized the aortic vasoconstrictive response in HbSS mice. In a randomized translational study, patients with SCD were treated with placebo or ambrisentan for 3 months, with the treatment group showing an increase in the percent brachial arterial diameter. Taken together, these data suggest that the ETA receptor pathway interaction with the adrenergic receptor pathway contributes to enhanced aortic vasoconstriction in SCD. Findings indicate the potential of ETA antagonism as a therapeutic avenue for improving vascular health in SCD.

Long-Term Safety and Efficacy of Macitentan in Inoperable Chronic Thromboembolic Pulmonary Hypertension: Results from MERIT and its Open-Label Extension.

Evidence for use of pulmonary arterial hypertension targeted-therapies in patients with chronic thromboembolic pulmonary hypertension (CTEPH) is limited. In MERIT-1, the endothelin receptor antagonist macitentan improved hemodynamic and functional parameters versus placebo in patients with inoperable CTEPH over a 24-week double-blind (DB) period. Its open-label (OL) extension study (MERIT-2) provides long-term safety/efficacy data. MERIT-2 (NCT02060721) was a multicenter, single-arm, OL, phase 2 extension study of MERIT-1. Patients completing MERIT-1 were eligible to receive 10 mg macitentan once-daily in MERIT-2. Safety and efficacy (6-min walk distance [6MWD] and change in World Health Organization functional class [WHO FC]) were assessed in all patients in MERIT-2 regardless of treatment received in DB (All patients MERIT-2 OL macitentan 10mg group) and the subgroup of patients receiving DB macitentan in MERIT-1 (Long-term [DB/OL] macitentan 10mg subgroup). Of the 80 patients randomized in MERIT-1, 76 entered MERIT-2 (All patients MERIT-2 OL macitentan 10mg group): 40 who received DB macitentan (DB-macitentan patients) and 36 DB placebo (DB-placebo patients). Median (interquartile range) macitentan exposure in the All patients MERIT-2 OL macitentan 10mg group was 45.5 (26.0, 66.1) months. During the OL period, treatment-emergent adverse events (AE) were reported in 72 (94.7%) patients; most frequent were worsening of pulmonary hypertension (19.7%), decreased hemoglobin (18.4%) and upper respiratory tract infection (15.8%). Fourteen (18.4%) patients died; none were assessed as macitentan-related. At Month 6 post-OL baseline, mean (standard deviation) change in 6MWD was - 0.4m (43.62) for DB-macitentan patients and 10.7m (45.63) for DB-placebo patients; the majority had unchanged (83.3%) or improved (12.5%) WHO FC. Safety/efficacy analyses were consistent in the Long-term (DB/OL) macitentan 10 mg subgroup. These analyses provide long-term safety/efficacy data in patients with inoperable CTEPH treated with macitentan. No unexpected safety findings occurred; reported AEs were consistent with the known safety profile of macitentan. At 6 months post-OL baseline, DB-placebo patients modestly improved 6MWD; DB-macitentan patients maintained improvements observed in MERIT-1. WHO FC was largely unchanged. ClinicalTrials.gov Identifiers: NCT02021292; NCT02060721.

Proteinuria and Progression of Renal Damage: The Main Pathogenetic Mechanisms and Pharmacological Approach.

The integrity of the glomerular filtration barrier maintains protein excretion below 150 mg/day. When urinary proteins increase, this indicates damage to the filtration barrier. However, proteinuria is not only a marker of kidney damage but also exacerbates it through various mechanisms involving the glomerular and tubulointerstitial compartments. Therefore, it is essential to intervene with renoprotective action that reduces the proteinuria. In this context, Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers are cornerstone treatments. Recent advancements include sodium-glucose cotransporter 2 inhibitors, initially used for glycemic control, now recognized for their renoprotective properties in both diabetic and non-diabetic populations. Another drug, Finerenone, a selective non-steroidal mineralocorticoid receptor antagonist, has emerged as a promising agent, offering anti-inflammatory and antifibrotic benefits with fewer side effects than traditional steroidal options. Finally, dual inhibition of angiotensin II and endothelin-1 receptors through agents like Sparsentan presents a novel approach with significant antiproteinuric effects in IgA nephropathy and focal segmental glomerulosclerosis. This brief review summarizes the mechanisms by which proteinuria promotes kidney damage and the renoprotective therapeutic approaches available, which can be combined with lifestyle modifications and specific treatments for underlying diseases to mitigate the progression of chronic kidney disease.

The effect of the endothelin receptor antagonist atrasentan on insulin resistance in phenotypic clusters of patients with type 2 diabetes and chronic kidney disease.

Type 2 diabetes (T2D) patients with a clinical phenotype characterized by a high degree of insulin resistance are at increased risk of chronic kidney disease (CKD). We previously demonstrated that the endothelin receptor antagonist (ERA) atrasentan reduced insulin resistance in T2D. In this study, we compared the effect of atrasentan on insulin resistance across different phenotypic clusters of patients with T2D. We performed a post hoc analysis of the SONAR trial, a randomized, placebo-controlled trial of the ERA atrasentan in patients with T2D and CKD. Patients were stratified into four previously identified phenotypic clusters: severe insulin-deficient diabetes (SIDD), severe insulin-resistant diabetes (SIRD), mild obesity-related diabetes (MOD) and mild age-related diabetes (MARD). Changes in insulin resistance, assessed by HOMA-IR, were compared between the phenotypic clusters using a mixed effects model. In total, 931 patients were included in the analysis. In the overall population, atrasentan compared to placebo reduced HOMA-IR by 12.9% [95%CI 3.5,21.4]. This effect of atrasentan was more pronounced in clusters characterized by insulin resistance or deficiency: (SIRD cluster 26.2% [95% CI 3.8,43.3] and SIDD cluster 18.5% [95%CI -3.8,35.9]), although the latter did not reach statistical significance. The effect of atrasentan compared to placebo was less pronounced in the other two clusters (MARD 12.2% [95% CI -1.7,24.12] and MOD -5.3% [95% CI -28.9,13.9]). Atrasentan significantly improved insulin sensitivity in patients with T2D and CKD, especially in those characterized by high insulin resistance (SIRD cluster). Further studies are warranted to investigate the long-term clinical outcomes of atrasentan treatment in these distinct phenotypic clusters.

YAP signaling orchestrates the endothelin-1-guided invadopodia formation in high-grade serous ovarian cancer.

The high-grade serous ovarian cancer (HG-SOC) is a notoriously challenging disease, characterized by a rapid peritoneal dissemination. HG-SOC cells leverage actin-rich membrane protrusions, known as invadopodia, to degrade the surrounding extracellular matrix (ECM) and invade, initiating the metastatic cascade. In HG-SOC, the endothelin-1 (ET-1)/endothelin A receptor (ETAR)-driven signaling coordinates invadopodia activity, however how this axis integrates pro-oncogenic signaling routes, as YAP-driven one, impacting on the invadopodia-mediated ECM degradation and metastatic progression, deserves a deeper investigation. Herein, we observed that downstream of the ET-1/ET-1R axis, the RhoC and Rac1 GTPases, acting as signaling intermediaries, promote the de-phosphorylation and nuclear accumulation of YAP. Conversely, the treatment with the dual ETA/ETB receptor antagonist, macitentan, inhibits the ET-1-driven YAP activity. Similarly, RhoC silencing, or cell transfection with a dominant inactive form of Rac1, restore the YAP phosphorylated and inhibited state. Mechanistically, the ET-1R/YAP signal alliance coordinates invadopodia maturation into ECM-degrading structures, indicating how such ET-1R-guided protein network represents a route able to enhance the HG-SOC invasive potential. At functional level, we found that the interconnection between the ET-1R/RhoC and YAP signals is required for MMP-2 and MMP-9 proteolytic functions, cell invasion, and cytoskeleton architecture changes, supporting the HG-SOC metastatic strength. In HG-SOC patient-derived xenografts (PDX) macitentan, turning-off the invadopodia regulators RhoC/YAP, halt the metastatic colonization. ET-1R targeting, hindering the YAP activity, weakens the invadopodia machinery, embodying a promising therapeutic avenue to prevent peritoneal dissemination in HG-SOC.

IgA Vasculitis (Henoch-Schönlein Purpura): An Update on Treatment.

Objective: IgA vasculitis (IgAV), previously named as Henoch-Schönlein purpura, is the most frequent systemic vasculitis in children. In adults, IgAV is less common although it is associated with more severe disease. In fact, the frequency of glomerulonephritis (referred to as IgAV nephritis) in adults is higher than in children and tends to present more severely, with around 10-30% of those affected eventually progressing to end-stage renal disease. In this review, we describe the pathophysiology, main clinical features, diagnosis of the disease, and latest clinical data regarding IgAV therapy. Methods: A narrative literature review, primarily based on articles published in PubMed, was conducted. In addition to discussing the main aspects of glucocorticoids and conventional disease-modifying drugs used in the management of IgAV, this review focuses on the latest information reported regarding biologics and potential future therapies. Results: Glucocorticoids are the first-line therapy for IgAV, especially in adults with severe manifestations. Colchicine, dapsone, and methotrexate can be useful for controlling minor manifestations. Several immunomodulatory agents, such as cyclosporine A, tacrolimus, and mycophenolate mofetil, have shown favorable results as glucocorticoid-sparing agents. Leflunomide has shown promising results but requires further study. The use of rituximab has demonstrated efficacy in reducing relapse frequency, lowering the cumulative glucocorticoid burden, and achieving long-term remission of the disease in children and adults with IgAV. Immunoglobulins and plasma exchange therapy can also be useful in difficult and life-threatening situations. Other potential therapies with encouraging results include TRF-budesonide, B-cell-directed therapy, B-cell-depleting agents, sodium-glucose cotransporter-2 inhibitors, endothelin receptor antagonists, and complement pathway inhibitors. Conclusions: Glucocorticoids are the first-line therapy for IgAV, especially in adults with severe manifestations. The role of various immunomodulatory therapies, such as calcineurin inhibitors and mycophenolate mofetil, remains promising, while rituximab reduces the long-term side effects of glucocorticoids and can help achieve disease remission. Other potential therapies with encouraging results require further research.

Non-HLA Autoantibodies Against Angiotensin II Receptor 1 (AT1R) and Endothelin A Receptor (ETAR) in Pediatric Kidney Transplantation.

Antibody-mediated rejection (AMR) is the leading cause of premature kidney transplant failure. The role of alloantibodies against Human Leukocyte Antigens (HLA) has been a primary focus in AMR. More recently autoantibodies and alloantibodies against the angiotensin II receptor type 1 (AT1R) and the endothelin A receptor (ETAR) have been linked to poor allograft outcomes in kidney transplantation. Nevertheless, evidence supporting routine testing remains insufficient. ELISA testing for anti-AT1R and anti-ETAR antibodies was performed in a pediatric renal transplant cohort. We selected 12 pediatric recipients who had undergone protocol biopsies and antibody measurements at 6 and 24 months post-transplant. Immunohistochemistry was performed on biopsies for AT1R and ETAR as well as the adhesion molecules ICAM-1 and VCAM-1. The analysis showed that ICAM-1 and VCAM-1 expression was significantly increased, along with the presence of circulating antibodies, in patients at 24 months post-transplant compared to patients without circulating antibodies. The presence of anti-AT1R and anti-ETAR antibodies does not seem to influence the expression of their receptors in the transplanted organ. Instead, the increase in adhesion molecules may precede the development of histological damage. Therefore, enlarging the cohort and extending long-term observation would help to understand the impact of anti-AT1R and anti-ETAR antibodies after transplantation.

EDNRA regulates the tumour immune environment and predicts the efficacy and prognosis of cancer immunotherapy.

The potential role of endothelin receptor A (EDNRA) in cancer immunotherapy has been demonstrated; however, the mechanism of its therapeutic value remains to be investigated. This study aimed to reveal the potential link between cancer immunotherapy and EDNRA in human tumours. Clinical characteristics and gene expression information were acquired from the Cancer Genome Atlas database. The correlation between EDNRA expression and immune infiltration was analysed by tumour immune estimation resource (TIMER) and tumour-immune system interaction database (TISIDB). EDNRA expression in different cancer types were performed via qPCR. Immunohistochemistry was used to detect the relationships between EDNRA protein and immune checkpoints. The results have founded that EDNRA was differentially expressed in various tumours, and highly associated with patient's age and tumour stage. It is also of high potential prognostic value in predicting patient survival. It has been verified that the EDNRA, JAK-STAT, and TGF-β signalling pathways are involved in cancers. In general, EDNRA positively correlated with immunomodulatory agents, immune cell infiltration, and immunotherapy markers. Immunohistochemical analysis of breast cancer tissues showed that EDNRA was positively correlated with NRP1 expression. Furthermore, patients with low EDNRA levels showed a superior response to immunotherapy. The functional study found that EDNRA expression is upregulated in MDA-MB-231 and HepG2 cells, and knockdown of EDNRA inhibits proliferation and migration of cells. In conclusion, the immunotherapeutic function of EDNRA was elucidated in this study. EDNRA may be an important target in tumour immunotherapy and provide new insights for tumour immunotherapy.

Novel pharmacologic approaches in resistant hypertension

Resistant hypertension (RH) affects 10% to 18% of all patients with hypertension. It is diagnosed when blood pressure cannot be normalized despite the use of 3 classes of antihypertensive drugs (ACE inhibitors or sartans), calcium antagonists and diuretics in maximum doses. If the above-mentioned drugs are ineffective, spironolactone is most often administered. Recently, valsartan/sacubitrol and flozins have been increasingly used in resistant hypertension, which have been introduced for the treatment of diseases other than hypertension but can be a supplement to previously used drugs in resistant hypertension. Pharmaceutical companies are currently working on a dozen or so antihypertensive drugs. The most advanced studies concern aldosterone synthesis inhibitors, an endothelin receptor antagonist, and a drug that inhibits angiotensinogen synthesis. The results to date allow for the consideration of aprocitentan (a drug that inhibits endothelin receptors) or baxdrostat or another new aldosterone synthesis inhibitor in the treatment of resistant hypertension that does not respond to 4 drugs, including spironolactone. Further studies are needed to confirm the efficacy and safety of these new drugs in the treatment of resistant hypertension.