Endothelin-1 is Increased in the Plasma of Patients Hospitalized with Covid-19

Importance The coronavirus disease 2019 (Covid-19) pandemic continues to place a devastating strain on healthcare services worldwide and there remains an ongoing requirement for new treatments. A key mechanism recognised in progressive severe disease is virus-induced endothelial dysregulation. Endothelin-1 (ET-1), being the most highly expressed peptide in endothelial cells and potent vasoconstrictor of human blood vessels, represents a potential therapeutic target through the use of Endothelin receptor antagonists. Objective To investigate the association of plasma ET-1 with Covid-19 disease severity Design Retrospective longitudinal cohort study of Covid-19 patients divided into Group A (asymptomatic or symptoms not requiring hospitalisation), Group B (symptoms requiring hospitalisation) and Group C (symptoms requiring supplemental oxygen therapy or assisted ventilation) recruited between March and July 2020 (the first wave of the Covid-19 pandemic in the UK). Data were compared with a contemporaneous cross-section of non-infected volunteers (Controls). Setting Single Tertiary National Health Service Hospital. Participants Tissue banked plasma samples were obtained from 194 patients. Exposures Quantitation of ET-1 in plasma by specific enzyme linked immunosorbent assay. Main outcome and measures Pairwise comparison of ET-1 levels (median [IQR]) between patient categories, and subgroups defined by clinical outcomes. Results Baseline ET-1 plasma levels (pg/ml) were elevated in patients requiring hospitalisation compared with controls and patients with asymptomatic or mild infection (Group B: 1.59 [1.13-1.98], and Group C: 1.65 [1.02-2.32] versus controls: 0.68 [0.47-0.87], p=<0.001 and Group A: 0.72 [0.57-1.10], p=<0.001). ET-1 levels were also elevated in patients that died (2.09 [1.66-3.15]), developed acute kidney (1.70 [1.07-2.36]) or myocardial injury (1.50 [0.92-2.28]) compared with patients with an uncomplicated infection (1.00 [0.61-1.57], p=<0.01). Amongst surviving hospitalised patients, ET-1 concentrations decreased when measured at 28 days (Group B: 0.86 [0.60-1.61] and Group C: 1.17 [0.66-1.62] versus baseline, p=<0.05) and 90 days (Group B: 0.69 [0.59-1.38] and Group C: 1.01 [0.64-1.21] versus baseline, p=<0.05). Conclusions and relevance Hospitalised Covid-19 patients demonstrate elevated ET-1 levels during the acute phase of infection and this is associated with increasing clinical severity of the disease. The results support the hypothesis that endothelin receptor antagonists may be beneficial for certain Covid-19 patients.

Novel Genome-wide Interactions Mediated via BOLL and EDNRA Polymorphisms in Intracranial Aneurysm

Association of boule (BOLL) and endothelin receptor type A (EDNRA) loci with intracranial aneurysm (IA) formation has been reported via genome-wide association studies. However, the underlying genome-wide interactions have yet to be reported. We sought to identify genome-wide interactions involving BOLL and EDNRA loci for IA. Genome-wide interaction analyses of BOLL and EDNRA involving 250 IA patients and 296 controls were performed under an additive effect model. Subsequent gene expression analyses were conducted using transcripts per million (TPM). A total of 23 and 11 SNPs suggested a genome-wide threshold (p < 1.25×10−8) interacting with rs700651 (BOLL) and rs6841581 (EDNRA), respectively. The rs1105980 (PTCH1) showed the most significant interaction with rs700651 (p = 6.41×10−11). The rs74585958 (RYK) interacted strongly with rs6841581 (p = 1.64×10−9). The BOLL-interacting CXCR4 was highly overexpressed in whole blood (TPM = 419.8) and CCDC3 was overexpressed in all artery-related tissues (TPM = 315.4 to 473.9). EDNRA-interacting EIF4H showed a comprehensively elevated expression across all tissues and cells (TPM = 85.8 to 372.0). Genome-wide interaction study shows that BOLL and EDNRA may contribute to IA formation by interacting with multiple genes in cardio-metabolic pathway. Our findings may provide insight into the functional relevant to IA susceptibility.

Effect of Dual Endothelin Receptor Antagonist on a Retinal Degeneration Animal Model by Regulating Choroidal Microvascular Morphology

Objective. Clinical studies have found that increasing levels of plasma endothelin-1 (ET-1) might inhibit choroidal blood flow (BF) and promote choroidal vasoconstriction. This study was designed to investigate ET-1 levels and its effect on choroidal microvascular morphology in a retinitis pigmentosa (RP) animal model. Methods. Mice with retinal degeneration (rd10) were intragastrically administered bosentan, a dual endothelin receptor antagonist. We detected plasma ET-1 levels using an enzyme-linked immunosorbent assay (ELISA) kit at P14, P21, and P28 and evaluated ET-1 expression in RPE/choroid/sclera complexes using western blot and whole mount immunofluorescence staining at P28. Retinal thickness was measured using hematoxylin and eosin (H&E) staining at P28. At the same time, we also estimated choroidal microvascular densities using vascular luminal casting with a scanning electron microscope (SEM). Results. Plasma ET-1 levels were increased significantly in rd10 mice at P21 (65.48 ± 24.83 pg/ml) and P28 (85.89 ± 20.23 pg/ml) compared with C57BL/6J mice at P21 (33.52 ± 16.33 pg/ml) and P28 (42.38 ± 17.53 pg/ml); the expression of ET-1 was also upregulated in RPE/choroid/sclera complexes at P28. Bosentan inhibited ET-1 expression in plasma ( P < 0.05 ) and RPE/choroid/sclera complexes at P28 in rd10 mice. Choroidal microvascular densities were decreased in rd10 mice, and bosentan could weaken these changes. Conclusion. Plasma and local ET-1 was elevated in an animal model of RP, suggesting that it likely participates in the pathological progression of retinal degeneration and may thus provide a new intervention target. ET-1 blockade might exert its protective effect by elevating choroidal microvascular density via inhibition of ET-1.

Endothelin Receptor Blockade Blunts the Pressor Response to Acute Stress in Obese Men and Women

Obesity is associated with dysregulation of the endothelin system. In obese individuals, an exaggerated pressor response to acute stress is accompanied by increased circulating endothelin-1. The impact of combined endothelin A/B receptor (ETA/B) antagonism on the stress-induced pressor response in overweight/obese individuals is unknown. Objective: To test the hypothesis that treatment with an ETA/B antagonist (bosentan) would reduce the stress-induced pressor response and arterial stiffness in overweight/obese compared to normal weight individuals. Methods: 40 participants [Normal weight (NW): n=20, BMI: 21.7 ± 2.4 kg/m2 & Overweight/obese (OB): n=20, BMI: 33.8 ± 8.2 kg/m2] were randomized to placebo or 125 mg of bosentan twice a day (250 mg total) for 3 days. Hemodynamics were assessed before, during, and after a cold pressor test (CPT). Endothelin-1 was assessed at baseline and immediately after CPT. Following a washout period, the same protocol was repeated with the opposite treatment. Results: The change from baseline in mean arterial pressure (MAP) during CPT following bosentan was significantly lower (p=0.039) in the OB group, compared to the NW group (OB: 28±12 vs LN: 34±15 mm Hg). Conclusions: These results suggest that ETA/B antagonism favorably blunts the pressor response to acute stress in overweight/obese individuals.

The Endothelin Receptor Antagonist Macitentan Inhibits Human Cytomegalovirus Infection

Human cytomegalovirus (HCMV) infection is an important cause of morbidity and mortality in immunocompromised patients and a major etiological factor for congenital birth defects in newborns. Ganciclovir and its pro-drug valganciclovir are the preferred drugs in use today for prophylaxis and treatment of viremic patients. Due to long treatment times, patients are at risk for developing viral resistance to ganciclovir and to other drugs with a similar mechanism of action. We earlier found that the endothelin receptor B (ETBR) is upregulated during HCMV infection and that it plays an important role in the life cycle of this virus. Here, we tested the hypothesis that ETBR blockade could be used in the treatment of HCMV infection. As HCMV infection is specific to humans, we tested our hypothesis in human cell types that are relevant for HCMV pathogenesis; i.e., endothelial cells, epithelial cells and fibroblasts. We infected these cells with HCMV and treated them with the ETBR specific antagonist BQ788 or ETR antagonists that are approved by the FDA for treatment of pulmonary hypertension; macitentan, its metabolite ACT-132577, bosentan and ambrisentan, and as an anti-viral control, we used ganciclovir or letermovir. At concentrations expected to be relevant in vivo, macitentan, ACT-132577 and BQ788 effectively inhibited productive infection of HCMV. Of importance, macitentan also inhibited productive infection of a ganciclovir-resistant HCMV isolate. Our results suggest that binding or signaling through ETBR is crucial for viral replication, and that selected ETBR blockers inhibit HCMV infection.

E.coli JM83 Damages Mucosal Barrier Inducing Hirschsprung-Associated Enterocolitis via Activated TLR4 / NF-κB / P-p38 Signaling

Purpose Hirschsprung-associated enterocolitis (HAEC) is characterized by intestinal mucosal damage and unbalance of intestinal microbiota. Recent studies have shown that the TLR4/NF-κB/p-p38 signaling in the intestine is of great importance to intestinal mucosal integrity. This study aimed to investigate the role of TLR4/NF-κB/p-p38 signaling in the pathogenesis of HAEC in Escherichia coli (E. coli) JM83 infected Endothelin receptor B (Ednrb)−/− mice. Methods Ednrb −/− mice were administered with E. coli JM83 by oral gavage to establish the HAEC model, mice were randomly divided into WT group, Ednrb−/− group and Ednrb−/−+ E. coli JM83 group. The role of TLR4/NF-κB/p-p38 signaling was evaluated by vivo study. Results The activation of the TLR4/NF-κB/p-p38 signaling induced by E. coli JM83 caused HAEC in Ednrb−/− mice, which was evidenced by a significantly increased expression of TNF-α, TGF-β and IL-10, decreased density of F-actin protein. While TLR4 knockdown improved the degree of enterocolitis and attenuated the expression of IL-10, TNF-α, TGF-β and increased the density of F-actin protein in Ednrb−/− mice after E. coli infection. Conclusions These results indicate that E. coli JM83 activates TLR4/NF-κB/p-p38 signaling to promote the development of HAEC. However, inhibition of this signaling may be benefit to the treatment and prevention of HAEC.

A human antibody against human endothelin receptor type A that exhibits antitumor potency

Endothelin receptor A (ETA), a class A G-protein-coupled receptor (GPCR), is involved in the progression and metastasis of colorectal, breast, lung, ovarian, and prostate cancer. We overexpressed and purified human endothelin receptor type A in Escherichia coli and reconstituted it with lipid and membrane scaffold proteins to prepare an ETA nanodisc as a functional antigen with a structure similar to that of native GPCR. By screening a human naive immune single-chain variable fragment phage library constructed in-house, we successfully isolated a human anti-ETA antibody (AG8) exhibiting high specificity for ETA in the β-arrestin Tango assay and effective inhibitory activity against the ET-1-induced signaling cascade via ETA using either a CHO-K1 cell line stably expressing human ETA or HT-29 colorectal cancer cells, in which AG8 exhibited IC50 values of 56 and 51 nM, respectively. In addition, AG8 treatment repressed the transcription of inhibin βA and reduced the ETA-induced phosphorylation of protein kinase B and extracellular regulated kinase. Furthermore, tumor growth was effectively inhibited by AG8 in a colorectal cancer mouse xenograft model. The human anti-ETA antibody isolated in this study could be used as a potential therapeutic for cancers, including colorectal cancer.