Neurological / neurovascular disorders constitute the leading cause of disability and second leading cause of deaths in the world. Some of the major neurological / neurovascular disorders or diseases include stroke, Alzheimer’s disease, spinal cord injury, neonatal hypoxic-ischemic encephalopathy, etc. Their pathophysiology is considered as highly complex and has been blamed as the main obstacle in the development of any drugs for these diseases. In this review, we have described the endothelin system, their involvement in neurovascular disorders, importance of endothelin B receptors (ETBRs) as a novel potential drug target, and its agonism by IRL-1620 (INN - sovateltide), which we are developing as a drug candidate for treating the above-mentioned neurological disorders / diseases. We have highlighted the results of our pre-clinical and clinical studies related to these diseases. The phase I, safety and tolerability study of sovateltide has shown it as a highly safe and well tolerable compound at tested dosages, while pre-clinical and clinical phase II studies have demonstrated its efficacy in treating acute ischemic stroke, where it is currently being developed as a “First in Class” drug. Its testing in Alzheimer’s disease (AD), acute spinal cord injury and neonatal hypoxic-ischemic encephalopathy (HIE) is currently being carried out and are at different stages of drug development. Successful completion of these studies will prove the involvement of ETBRs signaling in neurological / neurovascular diseases and help in development of novel neurological drugs in future.

Cardiac hypertrophy is an important and independent risk factor for the development of heart failure. To better understand the mechanisms and regulatory pathways involved in cardiac hypertrophy, there is a need for improved in vitro models. In this study, we investigated how hypertrophic stimulation affected human induced pluripotent stem cell (iPSC)-derived cardiomyocytes (CMs). The cells were stimulated with endothelin-1 (ET-1) for 8, 24, 48, 72, or 96h. Parameters including cell size, ANP-, proBNP-, and lactate concentration were analyzed. Moreover, transcriptional profiling using RNA-sequencing was performed to identify differentially expressed genes following ET-1 stimulation. The results show that the CMs increase in size by approximately 13% when exposed to ET-1 in parallel to increases in ANP and proBNP protein and mRNA levels. Furthermore, the lactate concentration in the media was significantly increased indicating that the CMs consume more glucose, a hallmark of cardiac hypertrophy. Using RNA-seq, a hypertrophic gene expression pattern was also observed in the stimulated CMs. Taken together, these results show that hiPSC-derived CMs stimulated with ET-1 display a hypertrophic response. The results from this study also provide new molecular insights about the underlying mechanisms of cardiac hypertrophy and may help accelerate the development of new drugs against this condition.

Objective: to retrospectively evaluate the incidence rate (IR) of echocardiographic signs suspected for pulmonary hypertension (PH) in Systemic sclerosis (SSc) patients after the introduction of a combination therapy with bosentan and sildenafil for treatment or prevention of digital ulcers. Methods: patients attending the Scleroderma Unit of the Universital Hospital of Careggi from July 2010 to July 2023 were enrolled. Patients older than 18 years old, with an history of digital ulcers, treated with bosentan and sildenafil in combination for at least 12 months were included. Patients with a diagnosis of PH preceding the introduction of the therapy were excluded. Demographical data, disease duration, laboratoristic and instrumental data (pulmonary function tests, echocardiographic estimation of pulmonary artery pressure (PAPs) and ultrasonographic value of renal resistive index) were collected. The IR of echocardiographic signs suspected for pulmonary hypertension and their 95% confidence interval were calculated in events/1000 patients-years.Results: forty-seven patients were enrolled; mean disease duration was 12,14 years (SD 5,87). Mean duration of the combination treatment was 78.33 (SD 41.37) months and total at-risk time was 3525 months. Two patients (4,2%) presented echocardiographic signs of PH (sPAP 50 mmHg and 40 mmHg); the IR was calculated to be 6.8/1000 patients-years (95% CI 6,02-7,7). In one of the 2 patients RHC excluded PAH, while the other patient refused to undergo to RHC and PAH could not be confirmed/excluded. A stability of PFTs and echocardiografic PAPs was observed during the observation time. Conclusions: the results of this retrospective study suggest that combination therapy with endothelin receptor antagonist and Phosphodiesterase-5 (PDE5) inhibitors could help in preventing PAH in SSc; prospective case-control studies on larger population are needed to improve knowledge in this field.

The ubiquitous peptide endothelin is currently under investigation as a modulatory factor of autonomic responses to acute emotional stress. Baseline plasma levels of endothelin alter blood pressor responses, but it remains unclear whether autonomic activity and arrhythmogenesis are affected. We recorded sympathetic and vagal indices (derived from heart rate variability analysis), rhythm disturbances, voluntary motion, and blood pressure after acute emotional stress in conscious rats with implanted telemetry devices. Two strains were compared, namely wild-type and ETB-deficient rats, the latter displaying elevated plasma endothelin. No differences in heart rate or blood pressure were evident, but sympathetic responses were blunted in ETB-deficient rats, contrasting prompt activation in wild-type rats. Vagal withdrawal was observed in both strains at the onset of stress, but vagal activity was subsequently restored in ETB-deficient rats, accompanied by low voluntary motion during recovery. Reflecting such distinct autonomic patterns, frequent premature ventricular contractions were recorded in wild-type rats, as opposed to sinus pauses in ETB-deficient rats. Thus, chronically elevated plasma endothelin levels blunt autonomic responses to acute emotional stress, resulting in vagal dominance and bradyarrhythmias. Our findings provide further insights into the pathophysiology of stress-induced tachyarrhythmias and syncope.

Chronic hemodialysis (HD) patients have very high cardiovascular risk. Acute vascular changes during dialysis mediated by factors of the endothelium may have a crucial role in this. Aim: To study acute vascular changes during HD. In 29 consecutive chronic HD patients (age: 65.6±10.4 years) pre-, mid-, and post-HD plasma syndecan-1 (SDC-1) and endothelin-1 (ET-1) levels were measured. Applanation tonometry was performed before HD. SDC-1 levels increased during HD (p=0.004). Males had higher ET-1 levels. Patients were divided into 2 groups based on pulse wave velocity (PWV): PWV≥12 m/s and PWV<12 m/s. Pre-HD and mid-HD SDC-1 levels were higher in the group with PWV≥12 m/s (10.174±2.568 vs. 7.928±1.794 ng/ml, p=0.013, and 10.319±3.482 vs. 8.248±1.793 ng/ml, p=0.044, respectively). Post-HD ET-1 levels were higher in the patient group having PWV≥12 m/s (10.88±3.00 vs. 8.05±3.48 pg/l, p=0.027). Patients having PWV≥12 m/s had higher pre-HD peripheral and aortic systolic blood pressure (p<0.05). Total cholesterol correlated with the SDC-1 decrease during HD (r=0.539; p=0.008). Pre-, mid-, and post-HD SDC-1 correlated with the ultrafiltration (r=0.432, p=0.019; r=0.377, p=0.044; and r=0.401, p=0.012, respectively). SDC-1 and ET-1 contribute to vascular changes observed during HD, and they have correlations with some cardiovascular risk factors.