Endothelin-1 Research Articles

CGS-21680 defers cisplatin-induced AKI-CKD transition in C57/BL6 mice

Acute kidney injury (AKI), with a high mortality and morbidity, is known as a risk factor for developing progressive chronic kidney disease (CKD). Targeting transition of AKI to CKD displays an excellent therapeutic potential. This study aims at investigating the role of CGS-21680, selective A2AR agonist, in deferring Cis-induced AKI-CKD transition. The AKI-CKD transition model was induced in C57/BL6 mice by repeated low doses of Cis (2.5 mg/kg i.p for 5 consecutive days in two cycles with a recovery phase of 16 days between two cycles). CGS-21680 was administered daily for 6 weeks (0.1 mg/kg, i.p). Urine, blood, and kidney were collected at three different time points to track the disease progression. CGS-21680 administration preserved kidney function and attenuated tubular damage as evidenced by hematoxylin-eosin (H&E) histopathology. CGS-21680 significantly restored oxidative status as reflected by reduced malondialdehyde (MDA) content and increased total antioxidant capacity (TAC). CGS-21680 showed anti-inflammatory effect as indicated by decreased TNF-α and iNOS. Additionally, CGS-21680 ameliorated endothelial dysfunction and enhanced renal vasodilation as evidenced by upregulation of endothelial nitric oxide synthase (eNOS) and nitric oxide (NO) expression and down regulation of endothelin-1 (ET-1) and its receptor endothelin-A (ET-A) receptor expression. CGS-21680 also attenuated renal fibrosis as reflected by the reduction of percentage of fibrosis in Masson's trichome-stained renal sections and down regulation of transforming growth factor beta1 (TGF-β1) protein expression in IHC-stained renal sections. In conclusion, CGS-21680 could defer Cis-induced AKI-CKD transition via its vasodilatory, antioxidant, anti-inflammatory, and anti-fibrotic effects.

Research on the Improvement of Endothelial Cell Function and Trophoblast Apoptosis in Rats with Preeclampsia by Tanshinone IIA

Background Preeclampsia is a pregnancy complication characterized by high blood pressure and signs of damage to another organ system, often the kidneys. Recent studies suggest that endothelial dysfunction and trophoblast apoptosis are involved in the pathogenesis of preeclampsia. Purpose To investigate the effects of tanshinone IIA (TIIA) on clinical symptoms, vascular endothelial function, and placental trophoblast apoptosis in preeclampsia rats. Materials and Methods Twenty-four pregnant Sprague-Dawley rats, between 8 and 10 weeks old, were randomly divided and allocated into three groups: Control, model, and treatment, with each group consisting of 8 rats. The control group received normal saline injections via the tail vein; the model group received NG-nitro-l-arginine methyl ester (l-NAME) to induce preeclampsia, followed by normal saline injections; and the treatment group received TIIA (10 mg/kg) via tail vein injection after preeclampsia induction with l-NAME. Various parameters were measured, including tail artery systolic pressure, 24-hour proteinuria, offspring and placental weight, levels of endothelial nitric oxide synthase (eNOS), endothelin-1 (ET-1), placental growth factor (PLGF), and soluble FMS-like tyrosine kinase 1 (sFlt-1) in serum, and expression of B-cell lymphoma-2 (Bcl-2) and Bcl-2-related X protein (Bax) in placental trophoblasts. Results TIIA treatment led to decreased tail artery systolic pressure and 24-hour urine protein levels, increased body and placental weights of offspring, and favorable changes in serum levels of ET-1, sFlt-1, eNOS, and PLGF. Moreover, TIIA treatment resulted in decreased Bax levels and apoptosis in placental trophoblasts, along with increased Bcl-2 levels. Conclusion TIIA can improve the clinical symptoms of preeclampsia in rats induced by l-NAME, alleviate the apoptosis of placental trophoblast cells, and improve vascular endothelial function.

Endothelial Cells Increase Mesenchymal Stem Cell Differentiation in Scaffold-Free 3D Vascular Tissue.

In this study, we present a versatile, scaffold-free approach to create ring-shaped engineered vascular tissue segments using human mesenchymal stem cell-derived smooth muscle cells (hMSC-SMCs) and endothelial cells (ECs). We hypothesized that incorporation of ECs would increase hMSC-SMC differentiation without compromising tissue ring strength or fusion to form tissue tubes. Undifferentiated hMSCs and ECs were co-seeded into custom ring-shaped agarose wells using four different concentrations of ECs: 0%, 10%, 20%, and 30%. Co-seeded EC and hMSC rings were cultured in SMC differentiation medium for a total of 22 days. Tissue rings were then harvested for histology, Western blotting, wire myography, and uniaxial tensile testing to examine their structural and functional properties. Differentiated hMSC tissue rings comprising 20% and 30% ECs exhibited significantly greater SMC contractile protein expression, endothelin-1 (ET-1)-meditated contraction, and force at failure compared with the 0% EC rings. On average, the 0%, 10%, 20%, and 30% EC rings exhibited a contractile force of 0.745 ± 0.117, 0.830 ± 0.358, 1.31 ± 0.353, and 1.67 ± 0.351 mN (mean ± standard deviation [SD]) in response to ET-1, respectively. Additionally, the mean maximum force at failure for the 0%, 10%, 20%, and 30% EC rings was 88.5 ± 36. , 121 ± 59.1, 147 ± 43.1, and 206 ± 0.8 mN (mean ± SD), respectively. Based on these results, 30% EC rings were fused together to form tissue-engineered blood vessels (TEBVs) and compared with 0% EC TEBV controls. The addition of 30% ECs in TEBVs did not affect ring fusion but did result in significantly greater SMC protein expression (calponin and smoothelin). In summary, co-seeding hMSCs with ECs to form tissue rings resulted in greater contraction, strength, and hMSC-SMC differentiation compared with hMSCs alone and indicates a method to create a functional 3D human vascular cell coculture model.

Exercise-Induced Shear Stress Drives mRNA Translation In Vitro.

The vascular endothelium is the first line of defense to prevent cardiovascular disease. Its optimal functioning and health are maintained by the interaction of the proteins-endothelial nitric oxide synthase (eNOS), sirtuin 1 (SIRT1), and endothelin 1 (ET1)-and the genes that encode them-NOS3, SIRT1, and EDN1, respectively. Aerobic exercise improves endothelial function by allegedly increasing endothelial shear stress (ESS). However, there are no current data exploring the acute effects of specific exercise-induced ESS intensities on these regulatory proteins and genes that are associated with endothelial function. The purpose of this study was to assess the acute changes in endothelial proteins and gene expression after exposure to low-, moderate-, and high-intensity exercise-induced ESS. Human umbilical vein endothelial cells (HUVECs) were exposed to resting ESS (18 dynes/cm2, 60 pulses per minute (PPM)), low ESS (35 dynes/cm2, 100 PPM), moderate ESS (50 dynes/cm2, 120 PPM), and high ESS (70 dynes/cm2, 150 PPM). Protein and gene expression were quantified by fluorescent Western blot and RTqPCR, respectively. All exercise conditions showed an increase in eNOS and SIRT1 expression and a decrease in NOS3 and SIRT1 gene expression when compared to resting conditions. In addition, there was no expression of ET1 and an increase in EDN1 gene expression when compared to resting conditions. These results show that (1) exercise-induced ESS increases the expressions of vascular protective proteins and (2) there is an inverse relationship between the proteins and their encoding genes immediately after exercise-induced ESS, suggesting that exercise has a previously unexplored translational role catalyzing mRNA to proteins.

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

Perivascular adipose tissue (PVAT) negatively regulates vascular muscle contraction. However, in the context of obesity, the PVAT releases vasoconstrictor substances that detrimentally affect vascular function. A pivotal player in this scenario is the peptide endothelin-1 (ET-1), which induces oxidative stress and disrupts vascular function. The present study postulates that obesity augments ET-1 production in the PVAT, decreases the function of the nuclear factor erythroid 2-related factor-2 (Nrf2) transcription factor, further increasing reactive oxygen species (ROS) generation, culminating in PVAT dysfunction. Male C57BL/6 mice were fed either a standard or a high-fat diet for 16 weeks. Mice were also treated with saline or a daily dose of 100 mg·kg-1 of the ETA and ETB receptor antagonist Bosentan, for 7 days. Vascular function was evaluated in thoracic aortic rings, with and without PVAT. Mechanistic studies utilized PVAT from all groups and cultured WT-1 mouse brown adipocytes. PVAT from obese mice exhibited increased ET-1 production, increased ECE1 and ETA gene expression, loss of the anticontractile effect, as well as increased ROS production, decreased Nrf2 activity, and downregulated expression of Nrf2-targeted antioxidant genes. PVAT of obese mice also exhibited increased expression of Tyr216-phosphorylated-GSK3β and KEAP1, but not BACH1 - negative Nrf2 regulators. Bosentan treatment reversed all these effects. Similarly, ET-1 increased ROS generation and decreased Nrf2 activity in brown adipocytes, events mitigated by BQ123 (ETA receptor antagonist). These findings place ET-1 as a major contributor to PVAT dysfunction in obesity and highlight that pharmacological control of ET-1 effects restores PVAT's cardiovascular protective role.

Evaluation of some nonroutine cardiac biomarkers among adults and children with beta-thalassemia major.

Cardiac injury caused by iron overload is the leading cause of mortality and morbidity in patients with beta-thalassemia, owing to frequent blood transfusion, increased iron overload, and blood hemolysis. This research aimed to assess several novel cardiac biomarkers in the blood samples of children and adult patients with beta-thalassemia major (βTM), along with their respective control groups. These biomarkers included endothelin 1 (ET-1), N-terminal pro-brain natriuretic peptide (NT-proBNP), atrial natriuretic peptide (ANP), growth differentiation factor-15 (GDF-15), and renalase (RNLS). This case-control study was done on 46 patients with βTM (23 children <18 years, and 23 adults ≥18 years) from the Genetic Hematology Center in Thi-Qar province, Iraq, and 42 comparable controls in 2 groups (21 for each group) in the period from February to April 2023. Levels of ET-1, NT-proBNP, ANP, GDF-15, RNLS, and ferritin were higher in the children and adults with βTM than in the control subjects. Elevations of the novel cardiac biomarkers ET-1, NT-proBNP, ANP, GDF-15, and RNLS in the sera of children and adult patients with βTM when compared with comparable control subjects confirm that the majority of patients with βTM are at risk of cardiac and cardiovascular complications even when there are no obvious symptoms, especially in children, which gives suitable predictive biomarkers.

Sparsentan improves glomerular hemodynamics, cell functions, and tissue repair in a mouse model of FSGS.

Dual endothelin-1 (ET-1) and angiotensin II (AngII) receptor antagonism with sparsentan has strong antiproteinuric actions via multiple potential mechanisms that are more pronounced, or additive, compared with current standard of care using angiotensin receptor blockers (ARBs). Considering the many actions of ET-1 and AngII on multiple cell types, this study aimed to determine glomeruloprotective mechanisms of sparsentan compared to the ARB losartan by direct visualization of its effects in the intact kidney in focal segmental glomerulosclerosis (FSGS) using intravital multiphoton microscopy. In both healthy and FSGS models, sparsentan treatment increased afferent/efferent arteriole diameters; increased or preserved blood flow and single-nephron glomerular filtration rate; attenuated acute ET-1 and AngII-induced increases in podocyte calcium; reduced proteinuria; preserved podocyte number; increased both endothelial and renin lineage cells and clones in vasculature, glomeruli, and tubules; restored glomerular endothelial glycocalyx; and attenuated mitochondrial stress and immune cell homing. These effects were either not observed or of smaller magnitude with losartan. The pleiotropic nephroprotective effects of sparsentan included improved hemodynamics, podocyte and endothelial cell functions, and tissue repair. Compared with losartan, sparsentan was more effective in the sustained preservation of kidney structure and function, which underscores the importance of the ET-1 component in FSGS pathogenesis and therapy.

Secretion of GPNMB from Neural Stem Cells Induced by ET-1 Contributes to Angiogenesis after Spinal Cord Injury.

The feeble plasticity of spinal cord microvascular endothelial cells (SCMECs) after trauma is one of the major causes of spinal cord injury (SCI). Neural stem cells (NSCs) play an important role in nerve repair. Glycoprotein nonmetastatic B (GPNMB) has neuroprotective effects and can be stimulated by endothelin 1 (ET-1), and its expression is upregulated in SCI. Here, we aim to investigate whether elevated ET-1 levels stimulate NSCs to secrete GPNMB, thereby further promoting angiogenesis. Mouse SCMECs and NSCs were isolated, cultured, and identified by flow cytometry and immunofluorescence staining. NSCs were treated with ET-1, while SCMECs were cocultured with NSCs, followed by treatment with ET-1. NCS and SCMEC viability were evaluated using cell counting kit 8 (CCK-8) assay, while cell proliferation, migration, invasion, and angiogenesis were examined using 5'-Ethynyl-2'-Deoxyuridine (EdU) staining, wound healing assay, Transwell assay, and tube formation assay. GPNMB expression in NCSs and SCMECs was quantified by western blot assay, quantitative Real-Time polymerase chain reaction (qRT-PCR), or enzyme-linked immunosorbent assay (ELISA). Mouse SCMECs and NSCs were successfully isolated and cultured. ET-1 promoted NSC viability and proliferation and upregulated GPNMB expression. NSCs and ET-1-treated NSCs promoted the viability, migration, invasion, angiogenesis, and GPNMB expression in SCMECs compared with control group cells, while GPNMB antibody reversed the above effects of ET-1 on the SCMECs. ET-1 promotes SCMEC migration and invasion, along with angiogenesis, by enhancing NSC-mediated GPNMB secretion, so ET-1 may be a novel therapeutic target for SCI.

Abstract P437: Correlation between plasma CT-proET-1 and renal dysfunction in patients with resistant hypertension. A biomarker analysis of the PRECISION study.

Hypothesis: Endothelin (ET)-1 is upregulated in hypertension and especially resistant forms of hypertension. As ET-1 is a paracrine hormone involved in renal organ damage, we investigated the correlation between eGFR and activity of the ET system in the resistant hypertensive population of the PRECISION trial (NCT03541174), in which aprocitentan, a dual endothelin ET A /ET B receptor antagonist, significantly reduced blood pressure and UACR. To assess activity of the ET system, ET-1 and CT-proET-1, a stable peptide and biomarker for ET-1 production, were measured in plasma. Methods: From plasma collected at screening from the future randomized patients in PRECISION, ET-1 (n=688) and CT-proET-1 (n=100, randomly selected) were measured by ELISA and LC-MS-based assays respectively. Baseline levels of CT-proET-1 were determined on pooled plasma from healthy adults (n=70). Pearson correlation coefficient was determined between biomarkers of the ET system and eGFR. Results: CT-proET-1 concentrations measured in patients with resistant hypertension were higher than concentrations from healthy subjects (83 vs 55 pM). In patients with an eGFR≥60 mL/min/1.73m 2 , mean CT-proET-1 concentration was 75 pM [95% CI 70-81; n=77] as compared to 116 pM [95% CI 95-140 n=23] in patients with eGFR&lt;60 mL/min/1.73m 2 . In these two subgroups, mean ET-1 concentrations were 1.90 ng/L [95% CI 1.85-1.95; n=531] and 2.10 ng/L [95% CI 1.99-2.22; n=157] for patients with an eGFR≥60 and eGFR&lt;60 mL/min/1.73m 2 respectively. There was an inverse correlation between CT-proET-1 and eGFR (r=-0.61, p&lt;0.0001) and a less pronounced correlation between ET-1 and eGFR (r=-0.11, p=0.0027) (see Figure ). Conclusions: In patients with resistant hypertension, there was a strong inverse correlation between plasma CT-proET-1 and renal function, suggesting the role of the ET system not only in hypertension but also in renal damage. These data demonstrate that CT-proET-1 is a sensitive biomarker of the ET system, reflecting the production of ET-1.

Association of plasma endothelin-1 levels with revascularization strategies and short-term clinical outcomes: Role of diabetes

Mortality rate due to coronary artery disease (CAD) is elevated among diabetes mellitus (DM) compared to non-DM patients. Endothelin 1 (ET-1), a potent vasoconstrictor, is implicated in the pathophysiology of both CAD and DM. The impact of ET-1 on the short-term clinical outcomes following revascularization by percutaneous coronary intervention (PCI) and coronary artery bypass surgery (CABG) remains unclear. We investigated the impact of ET-1 on clinical outcomes and revascularization strategies in CAD patients, exploring the role of DM on modifying these relationships. In a prospective observational study, patients presenting to cardiac catheterization lab for CAD evaluation at a Jordanian hospital were enrolled and stratified by status of CAD and DM. Plasma levels of ET-1 were measured before catheterization. Short-term clinical outcomes and prognosis were compared.Among 815 enrolled patients (603 CAD and 212 controls), DM prevalence was higher among CAD patients than non-CAD. Plasma ET-1 levels were measured in 490 random patients and were associated with CAD and the need for revascularization. Multivariate analysis independently revealed higher plasma ET-1 levels in DM patients requiring revascularization. Short-term follow-up for 366 patients (median of 4 months) showed that 132 developed one cerebro/cardiovascular event, predominantly among DM patients. Baseline ET-1 was not associated with higher risk of the first event. Notably, revascularization by PCI was associated with lower event risk in DM patients.Our study indicates that plasma ET-1 levels are associated with the need for revascularization in DM patients, with those undergoing PCI having a lower risk of initial cerebro/cardiovascular events.

Abstract 19: Effect of the endothelin receptor antagonist aprocitentan on plasma endothelin, renin and aldosterone concentrations in patients with resistant hypertension. A biomarker analysis of the PRECISION study.

Hypothesis: Dual endothelin (ET) ET A /ET B receptor antagonist aprocitentan significantly reduced blood pressure in patients with resistant hypertension, who were still hypertensive despite standard background anti-hypertensive drugs including a diuretic, an ARB and a CCB (PRECISION trial, NCT03541174). The effect of aprocitentan in this population, characterized with low renin and elevated aldosterone levels, was assessed on a panel of plasma biomarkers: ET-1, CT-proET-1 (a stable peptide and biomarker for ET-1 production), renin, aldosterone. Methods: From the 730 randomized patients in PRECISION, ET-1 (n=700), CT-proET-1 (n=100, randomly selected), immunoreactive renin (n=679) and aldosterone (n=703) were measured in plasma samples collected at randomization (baseline) and after 4 weeks for either placebo, aprocitentan 12.5 or 25 mg. Results: Four-week placebo treatment had no effect on the studied biomarkers compared to baseline. Treatment with aprocitentan 12.5 and 25 mg increased plasma ET-1 by +34% and +53% and CT-proET-1 by +38% and +47% vs. baseline respectively. Aprocitentan had no effect on renin levels (p&gt;0.05) while decreasing plasma aldosterone by -17% and -24% at the 12.5 and 25 mg dose respectively. Importantly, the reduction in aldosterone did not result in a change in kalemia (see Table ). Conclusions: Aprocitentan caused reactive dose-dependent increases in plasma CT-proET-1 and ET-1, resulting from effective ET receptor blockade. The increase in CT-proET-1 may indicate a compensatory increase in ET-1 de novo synthesis, while the increase in ET-1 may reflect a reduced clearance due to blockade of ET B and increased production. The decrease of aldosterone by aprocitentan confirms the secretagogue role of ET-1 on aldosterone production by adrenal cortical cells via both ET A and ET B receptors This decrease of aldosterone was observed on top of the known decrease induced by an ARB but did not induce hyperkalemia nor aggravation of renal function.

The Predictive Value of PKC and ET-1 Levels in Cerebrospinal Fluid for Vasospasm and Prognosis in Patients with Aneurysmal Subarachnoid Hemorrhage.

To analyze the predictive value of protein kinase C (PKC) and endothelin-1 (ET-1) in cerebrospinal fluid for vasospasm and prognosis in patients with aneurysmal subarachnoid hemorrhage (ASH). One hundred and forty-eight ASH patients hospitalized in our hospital during February 2019 to February 2022 were optioned as observation subjects. These subjects were graded into good prognosis group (mRS score 0-2, n = 102) and poor prognosis group (mRS score 3-6, n = 46) according to the Rankin Revised Scale Score (mRS) after 6 months of follow-up. Cerebrospinal fluid was collected from patients to detect the content of ET-1 and PKC. The prognostic factors were analyzed using multifactorial logistic regression. The predictive value was assessed using receiver operating characteristic (ROC) curve. The patients with poor prognosis had a higher age level and a higher proportion of ≥2 aneurysms, aneurysm diameter ≥6 mm, cerebral vasospasm, and Hunt-Hess grade ≥III than those with good prognosis (P < 0.05). The patients with poor prognosis had higher content of PKC and ET-1 than those with good prognosis (P < 0.05). Age, aneurysm diameter ≥6 mm, cerebral vasospasm, Hunt-Hess classification ≥grade III, PKC and ET-1 were all risk factors related to the prognosis of ASH (P < 0.05). The area under the curve (AUC) of PKC and ET-1 for diagnosing poor prognosis of ASH was 0.803 and 0.720, respectively. The AUC of the combined detection was 0.873 (P < 0.05). Patients with cerebrovascular spasm had higher content of PKC and ET-1 than those without (P < 0.05). The AUC of PKC and ET-1 for diagnosing cerebral vasospasm in ASH was 0.891 and 0.816, respectively, which was 0.932 for combined detection (P < 0.05). The combination of PKC and ET-1 in cerebrospinal fluid had certain value in predicting the poor prognosis of patients with ASH.

Abstract P146: Sex-Dependent Regulation of the Endothelin System in Multi-End Organ Inflammation in Lupus-Associated Cardiovascular Disease

Lupus is a chronic autoimmune disease characterized by IgG deposition, Toll-like receptor 7 (TLR7) overactivation, and autoantibody production resulting in end organ inflammation. SLE disproportionally affects women, SLE disproportionally affects women to men (9:1 ratio), with a high prevalence in African American women. Highly vascularized organs are severely impacted by lupus, specifically the kidneys and brain. Recent literature has shown that cardiovascular disease (CVD) has significant detrimental impacts on organ crosstalk. Endothelin-1 (ET-1), a potent vasoconstricting peptide, has been shown elevated in patients with CVD and in patients with lupus independent of disease severity. However, the extent to which ET-1 promotes lupus-associated CVD and end organ cross talk remains to be elucidated. Therefore, we hypothesized that TLR7 overactivation in a murine model of SLE-associated CVD would lead to a sex-dependent regulation of the renal and cerebral ET systems. Female and male lupus-prone B6.Nba2 mice were subjected to bi-weekly treatment with the Resiquimod (R848; TLR7/8 agonist; 100ug/30ul) or vehicle control (Acetone) for one month and subsequently studied for 12 weeks. At 16 weeks, the kidneys and brains were collected for histology and ET system (ET-1, ET A, and ET B ) analysis. Exploration of specific end organ damage demonstrates a profound increase in renal and cerebral IgG complex deposition as well as renal macrophages and T cells in both females and males receiving R848. Renal ET-1 levels displayed no time nor treatment-dependent effects in females, while males exhibited a significant time-dependent increase in expression at the 4 and 16-week timepoints. Interestingly, at the receptor level, neither sex demonstrated differences in ET A nor ET B levels in the kidney. While renal ET-1 level did not change, females demonstrated a significant increase in cerebral ET-1 at the 16-week timepoint, while males trended for increased cerebral ET-1. At the receptor level, females had a trend for increased cerebral ET A expression, while there was no change in males, and neither sex displayed a change in ET B receptor expression. These findings suggest a potential shift towards a pro-inflammatory state via the cerebral ET-1/ET A signaling axis in the R848-treated females. These findings warrant further exploration into the end-organ specific pathophysiological role ET-1/ET A signaling in multiorgan crosstalk in lupus-associated CVD.

Abstract 35: The Dual Endothelin-1 Antagonist Aprocitentan Attenuates Mitochondrial Oxidative Stress in Human Cardiac Fibroblasts

Endothelin-1 (ET-1) is a peptide hormone primarily produced by endothelial cells that functions as a potent vasoconstrictor through two receptors, ETA and ETB. While most research on ET-1 has focused on endothelial dysfunction and hypertension, increasing evidence shows that ET-1 is also involved in other physiological processes such as cell proliferation, inflammation, and tissue remodeling. Dysregulation of ET-1 has been implicated in the pathogenesis of various diseases, including heart failure, atherosclerosis, fibrosis, systemic sclerosis, and cancer. Aprocitentan (also known as ACT-132577) is a relatively new dual ET-1 receptor antagonist that prevents ET-1 from binding to both endothelin receptors and has been shown to significantly reduce blood pressure in patients with resistant hypertension. Our hypothesis was that aprocitentan could reduce the proliferation rate and mitochondrial ROS production induced by TGF-β in human cardiac fibroblasts (HCFs). HCFs were isolated from hearts from fully de-identified cadaveric donors and cultured in cardiac fibroblast growth medium. HCFs were treated with aprocitentan (4 μM) and/or TGF-β1 (10 ng/ml) for 72 hours (doses and times identified in preliminary dose-response and time-course assays). Aprocitentan reduced the TGF-β1-induced proliferation rate in HCFs by approximately 23% ( Figure 1A ). Our study also aimed to determine if aprocitentan could mitigate mitochondrial dysfunction. Since the mitochondrion is a major source of reactive oxygen species (ROS), which can promote myofibroblast differentiation, mitochondrial properties in HCFs were assessed using MitoTracker Green and MitoSOX staining. TGF-β1 treatment increased mitochondrial ROS production, which was significantly reduced by aprocitentan ( Figure 1BC ); furthermore, aprocitentan reduced mitochondrial fragmentation induced by TGF-β1 treatment ( Figure 1D ). To the best of our knowledge, we are the first to demonstrate that aprocitentan can reduce the increased production of mitochondrial ROS, mitochondrial fragmentation, and cell proliferation rate induced by TGF-β1 in HCFs. This discovery could pave the way for new research and therapeutic strategies for treating fibrosis in cardiovascular disorders.

Abstract P178: Sex Differences in the Role of the Immune ET-1/ET A Axis in Controlling Blood Pressure during a Hypertension Challenge

Immune cells like dendritic cells (DCs) and T cells are essential for the development of hypertension. Upregulation of the vasoactive peptide endothelin-1 (ET-1) is key in the progression of hypertension. ET-1 acting via its ET A receptor raises blood pressure and promotes end-organ damage and inflammation. DCs and T cells express ET-1 receptors and respond to changing levels of ET-1. However, it is unknown whether activation of the ET-1/ET A receptor axis on DCs or T cells is critical in driving hypertension, or if a differential activation of this axis in immune cells leads to the sex differences that exist in the pathophysiology of this disease. We hypothesized that activation of the ET-1/ ET A axis on immune cells is crucial in the development of hypertension, with a more prominent role in males than females. Male and female mice lacking ET A receptor on DCs (DC ET A KO) or on T cells (T cell ET A KO) and floxed ET A control mice were given the nitric oxide synthase inhibitor L-NAME (0.5 mg/mL) in drinking water for 3 wks to induce hypertension. Systolic blood pressure (SBP) was measured 3 times/wk via tail cuff plethysmography. Glomerular filtration rate (GFR) was evaluated at baseline and after L-NAME treatment via the transcutaneous FITC-sinistrin clearance method. Absence of ET A receptor on DCs resulted in a ~10 mmHg decrease in SBP at baseline in both sexes, and this difference increased throughout the protocol in males (Floxed ET A vs. DC ET A KO: L-NAME: 150.8±6.7 vs. 130.8±2.6 mmHg, n=4/group, p=0.002), but not in females (137.4±5.7 vs. 137.2±2.4 mmHg, n=3/group). Lack of the ET A receptor on T cells led to a similar decrease of ~10 mmHg in SBP at baseline. However, the difference in SBP widened when males were challenged with L-NAME (Floxed ET A vs. T cell ET A KO: 135.2±2.0 vs. 118.0±4.1, n=11/group, p=0.003), whereas the group difference in SBP disappeared in females (131.5±4.0 vs. 132.4±4.7, n=8-9/group). Following L-NAME, GFR trended to decline in control male mice, while it increased in T cell ET A KO males. Our data suggest that activation of ET A receptors on DCs and T cells modulates SBP in response to a hypertensive insult in males, but not in females. Additionally, absence of ET-1/ ET A axis activation on T cells suggests improved renal function during hypertension. Our results suggest that the use of ET A antagonism in the clinic may be more protective during hypertension in males than females.

Abstract 34: Elevation of Plasma anti-Endothelin A Receptor Autoantibodies in Lupus Subjects Correlates with Plasma Vascular Adhesion Molecule-1 Independent of Blood Pressure

Systemic Lupus Erythematosus (SLE) is an autoimmune disease that is characterized by deposition of autoantibodies and their immune complexes, resulting in inflammation, and end-organ damage to the kidney and vasculature. SLE disproportionally affects women to men (9:1 ratio), with a high prevalence in African American women and patients often have cardiovascular complications including hypertension (HTN). The activation of the endothelin (ET) system has been implicated in numerous pathological disease states including HTN, SLE, and diabetes. Recently, dual ET receptor antagonism was approved for treatment of patients with uncontrolled hypertension. Studies have demonstrated the presence of biologically active endothelin A receptor autoantibodies (ETAR-AAs) in systemic sclerosis and cystic fibrosis patients. Few studies have investigated the role of the synergistic interplay of SLE and HTN on ETAR-AAs. We hypothesized that women with SLE and HTN would have elevated plasma ETAR-AAs compared to control or SLE only subjects. To investigate this, we recruited non-SLE non-HTN controls (n=10), non-SLE HTN (n=10), SLE non-HTN (n=8), and SLE-HTN (n=10) female human subjects and analyzed clinical characteristics, plasma ETAR-AAs, soluble vascular adhesion molecule-1 (sVCAM-1) and soluble intracellular adhesion molecule-1 (sICAM-1). Plasma ETAR-AAs did not significantly correlate with either age (r=-0.1375; p=0.4453) or body mass index (r=-0.3149; p=0.0743). When subjects were categorized by SLE or HTN diagnosis, we found that subjects with SLE had a profound increase in ETAR-AAs compared to non-SLE controls (p&lt;0.0001) while the levels were similar between HTN and non-HTN controls (p=0.7626). Next, we stratified subjects by blood pressure status and found a significant elevation in plasma ETAR-AAs in SLE non-HTN over non-SLE HTN subjects (p=0.0121), while SLE-HTN subjects had significant elevations in ETAR-AAs compared to both non-SLE non-HTN (p=0.0183) and non-SLE HTN (p=0.0014) subjects. We correlated plasma levels of ETAR-AA with sVCAM-1 and sICAM-1 and found that plasma ETAR-AAs were positively associated with plasma sVCAM-1 (r=0.4288; p=0.0114) and sICAM-1 (r=0.3812; p=0.0286). These data indicate that irrespective of blood pressure status, elevated plasma ETAR-AAs are associated with markers of vascular dysfunction in SLE subjects. Further investigation of cell-specific ETAR-AA and ETAR signaling should be performed in murine models and human subjects with SLE.

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

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

Color Doppler Imaging, Endothelin-1, Corneal Biomechanics and Scleral Rigidity in Asymmetric Age-Related Macular Degeneration.

Age-related macular degeneration (AMD) presents a multifaceted etiopathogenesis involving ischemic, inflammatory, and genetic components. This study investigates the correlation between ocular hemodynamics, scleral rigidity (SR), and plasma endothelin-1 (ET1) levels in treatment-naive patients with asymmetrical AMD. This study included 20 treatment-naive patients (12 females and 8 males) with an average age of 76.4 ± 3.7 years, who presented with AMD with neovascular membrane formation (nAMD) in one eye, and intermediate grade 2 AMD (iAMD) in the other eye. The control group consisted of 20 healthy subjects (13 females and 7 males) with a mean age of 74.7 ± 3.9 years. All patients and healthy controls underwent color Doppler imaging (i) of the ophthalmic artery (OA), short posterior ciliary arteries (SPCAs), and central retinal artery (CRA); Plasma ET-1 levels were measured for all patients and healthy subjects. Corneal biomechanics were assessed using an Ocular Response Analyzer and two indices were obtained: corneal hysteresis (CH) and corneal resistance factor (CRF). Results showed reduced blood flow velocities and increased resistance indices in AMD eyes, particularly affecting the short posterior ciliary arteries. According to mechanical theory, ARMD eyes exhibited elevated scleral rigidity and corneal resistance factor compared to controls, with a notable rise in SR in neovascular AMD (nAMD) eyes. As per the chronic subacute inflammation theory, plasma ET-1 levels were significantly higher in AMD patients, correlating with abnormal SPCAs blood flow and increased resistance indices. Findings suggest a multifactorial etiology of AMD involving an increase of ET-1 plasma levels with biomechanic damages of corneal and scleral tissue in nAMD.

Effect of Levobupivacaine Hydrochloride-Loaded Nanospheres on Delayed Cerebral Vasospasm Following Subarachnoid Hemorrhage in Rabbits

This research was aimed to analyze the mechanism of action of levobupivacaine hydrochloride-loaded nanospheres on delayed cerebral vasospasm following subarachnoid hemorrhage (SAH). Levobupivacaine hydrochloride-loaded nanospheres (LevoBPV Hcl/PLGA) were prepared using the solvent evaporation methodology, with the raw material as a control. The blood drug concentrations were detected by HPLC after subcutaneous and subarachnoid administration in experimental rabbits. Forty New Zealand white rabbits were randomly assigned into Sham group, SAH group, LevoBPV Hcl group (10 mg/kg), and LevoBPV Hcl/PLGA group (10 mg/kg), with 10 rabbits in each group. The SAH model was induced using the double blood injection methodology combined with internal carotid artery ligation. Brain tissue samples were collected on day 7 for pathological characterization, determination of neuronal apoptosis, and measurement of basilar artery diameter and area. The levels of oxidative stress factors (superoxide (SOD), malondiadehyde (MDA), glutathione peroxidase (GSH-Px)) and vasoconstrictor factors (nitric oxide (NO), endothelin-1 (ET-1)) in the cerebrospinal fluid (CSF) were detected using assay kits. The results revealed that the drug loading capacity of LevoBPV Hcl/PLGA was 29.13%, encapsulation efficiency was 87.09%, and the average particle size was 81.43 μm. Under the same dosage, both subcutaneous and subarachnoid administration of LevoBPV Hcl/PLGA exhibited two concentration peaks in the blood drug concentration, with lower concentration values versus LevoBPV Hcl group, and a longer average residence time than LevoBPV Hcl group (P &lt; 0.05). Relative to Sham group, SAH group exhibited decreased diameter and area of the basilar artery, reduced neuronal density, increased neuronal apoptosis rate, decreased levels of SOD, GSH-Px, and NO in the CSF, and increased levels of MDA and ET-1 (P &lt; 0.05). Moreover, LevoBPV Hcl group and LevoBPV Hcl/PLGA group showed increased diameter and area of the basilar artery, higher neuronal density, reduced neuronal apoptosis rate, elevated levels of SOD, GSH-Px, and NO in the CSF, and decreased levels of MDA and ET-1 versus SAH group (P &lt; 0.05). The LevoBPV Hcl/PLGA group exhibited increased diameter and area of the basilar artery, higher neuronal density, reduced neuronal apoptosis rate, elevated levels of SOD, GSH-Px, and NO in the CSF, and decreased levels of MDA and ET-1 versus LevoBPV Hcl group (P &lt; 0.05). In short, LevoBPV HCl-loaded nanospheres can prolong the in vivo residence time of subcutaneous and subarachnoid administration, reduce the maximum blood drug concentration, and enhance drug safety. Furthermore, these nanospheres can inhibit neuronal apoptosis following SAH, regulate oxidative stress and vasoconstrictor factor expression, thereby suppressing the occurrence of delayed cerebral vasospasm and alleviating brain tissue damage.

Abstract 15: Cell-Free Mitochondrial DNA Drives Endothelial Cell Activation and Vascular Dysfunction via Toll-Like Receptor 9 and Inflammasome Pathway Activation

Immune system activation has been shown to play an important role in the pathogenesis of hypertension and substantial evidence has been highlighting the importance of inflammasomes in vascular disease progression. Mitochondria damage leads to mitochondrial DNA (mtDNA) releasing into the cytoplasm, which, in turn, triggers the activation of leucine-rich-containing (NLR) family pyrin domain containing 3 (NLRP3) and absent in melanoma 2 (AIM2) inflammasomes, thereby exacerbating inflammation. However, whether mtDNA release-dependent exacerbation of inflammasomes drives endothelial cell activation and vascular damage remains to be elucidated. We hypothesize that cytosolic mtDNA release triggers endothelial cell activation and inflammation via Toll-Like Receptor 9 (TLR9) and inflammasome pathway activation, leading to vascular dysfunction. To assess this hypothesis, a concentration-response curve to endothelin-1 (ET-1) was performed in mesenteric resistance arteries (MRAs) isolated from wild-type and TLR9 knockout C57 mice in the presence or absence of mtDNA (4ug/mL) for one hour. To test inflammasome pathway activation, vascular smooth muscle cells (VSMC) and endothelial cells (EC) were incubated with TLR9 agonist (ODN2395, 3uM) or mtDNA (4ug/mL) and co-incubated with TLR9/AIM2 inhibitor (ODN2088, 2uM) or NLRP3 inhibitor (MCC950, 10uM) for 24 hours. Protein expression was assessed via Western blot and immunophenotyping was performed by flow cytometry. Data are presented as mean ± S.E.M and significance was set at p&lt;0.05. After incubation with mtDNA, MRAs from wild-type mice presented an increased contractile response to ET-1 which was prevented in TLR9 KO mice. In VSMC, TLR9 expression increased after incubation with ODN2395 (vehicle: 1.2 ± 0.2 vs ODN2395: 4 ± 1.5) or mtDNA (vehicle: 1.2 ± 0.2 vs mtDNA: 4.2 ± 1.2) while co-incubation with ODN2088 reversed this effect. Additionally, mtDNA promoted increased TNF-alpha (vehicle: 1 ± 0.1 vs mtDNA: 2.6 ± 0.5) and IL-6 (vehicle: 1 ± 0.1 vs mtDNA: 4.6 ± 0.3) expression in VSMC which was abolished in the presence of ODN2088. In EC, flow cytometry indicated that incubation with mtDNA promoted a 4-fold increase in the expression of CD31+ and a 2-fold increase in CD54+ cells while co-incubation with ODN2088 or MCC950 reversed this effect. Altogether these data suggest that cell-free mtDNA triggers the innate immune response via TLR9 and inflammasomes driving EC activation, vascular dysfunction, and inflammation.