Pathological interactions between the endothelin-1 and the angiotensin- converting enzyme among Tunisian coronary patients

Background

The correct understanding of the biochemical and metabolic interactions between coronary risk factors contribute to the exploration of cardiovascular pathophysiology and improves therapeutic care.

The aim of this study was to explore the endothelin-1 (ET-1) concentration and the angiotensin converting enzyme (ACE) activity among Tunisian patients with coronary heart disease, and to investigate the metabolic relationships between these two markers,… and to assess the possible relationship between them and the different risk factors.

In this present study, ET-1 concentration was determined by an analytical method (High Performance Chromatography, coupled by Mass Spectrometry), ACE activity was measured by a kinetic method for patients and healthy controls. These subjects (157 patients and 142 controls) beneficed also by a biochemical exploration (lipid, apolipoproteins and glucose profiles) to quantify cardiovascular risk.

Results

A statistically significant increase of the ET-1 concentration was found among patients compared to healthy controls (15.2 ± 5.3 nM vs 7.1 ± 2.7 nM, p < 0,00001). For the ACE activity, in spite the treatment of the majority of patients (97%) with ACE inhibitors, this activity was statistically elevated in patients compared to healthy subjects (86.7 ± 25.4 IU/L vs 42.8 ± 12.1 IU/L, p < 0.00001).

Furthermore, a statistically positive correlation was identified between these two cardiac markers (r = 0.68 p < 0.00001).

Conclusion

The study of the metabolic relationship between the ET-1 and ACE among coronary patients reveals other therapeutics targets.

Proteomic Analysis of Endothelin-1 Targets in the Regulation of Cardiomyocyte Proliferation

Hypoxia is a fetal stressor that leads to the production of endothelin-1 (ET-1). Previous work has shown that ET-1 treatment leads to the premature terminal differentiation of fetal cardiomyocytes. However, the precise mechanism is unknown. We tested the hypothesis that the fetal cardiomyocyte proteome will be greatly altered due to ET-1-treatment, which reveals a potential molecular mechanism of ET-1-induced terminal differentiation. Over a thousand proteins were detected in the fetal cardiomyocytes and among them 75 proteins were significantly altered due to ET-1 treatment. Using IPA pathway analysis, the merged network depicted several key proteins that appeared to be involved in regulating proliferation, including: EED, UBC, ERK1/2, MAPK, Akt, and EGFR. EED protein, which is associated with regulating proliferation via epigenetic mechanisms, is of particular interest. Herein we propose a model of the molecular mechanism by which ET-1 induced cardiomyocyte terminal differentiation occurs.

Molecular mechanisms of pruritus

Pruritus is an unpleasant sensation that evokes the urgent desire to scratch. It is a symptom derived from many nervous system disorders that affects a large population of humans and is treated by a variety of pharmacological agents with variable access. Chronic itch is a huge unmet health problem which affect upward 20% of people worldwide. The mechanisms underlying the chronic pruritus are complex. Studies of the neurobiology, neurophysiology and cellular biology of itch have gradually been clarifying the mechanism of chronic itch both peripherally and centrally. The discussion has been focused on pruriceptive nerves and their receptors as well as the cytokines/chemokines that play major roles in itch induction. Though it is historically hypothesized that pain convey signal generated with the stimuli under high intensity, and itch transduces signal from the same nerves of pain but under low intensity, recently, with the identification of distinct itch specific sensory afferent fibers the theory has twisted the "intensity" to a existence of a complete separation of pain and itch pathways. This review helps to understand the unique properties of itch signaling pathways and their clinical importance of the itch perception and pruritic diseases.

Establishment and characterization of porcine focal cerebral ischemic model induced by endothelin-1

BACKGROUND AND PURPOSE

Due to well-developed Circle of Willis in pigs, it is technically challenging to make persistent focal ischemic stroke based on occlusion of cerebral arteries. Endothelin-1 could cause a focal lesion by forcing transient but strong vasoconstriction in the circumscribed injected area. Its use in porcine stroke model has drawn attention lately. However, all the porcine endothelin-1 induced models were euthanized soon after surgery. Whether the brain lesion is persistent, and whether they could cause neurological deficit are not known. This research aims to provide a more detailed characterization of endothelin-1 induced porcine cerebral ischemic model by evaluating the change of neurological function and the brain lesion monitored by MRI of the pigs.

METHODS

Danish Domestic pigs were randomly divided into two groups: a group receiving endothelin-1 (ET-1 group, n=6) and a sham group (n=6). After the fronto-temporal craniotomy, pigs in the ET-1 group received 200μl endothelin-1 injected within a cortical area of one cm²; pigs in the sham group received only saline injections. Neurological deficit evaluation and MRI scanning were done 24h and 72h after operation. Afterwards, hematoxylin and eosin staining was conducted to detect the morphological characteristics of the damaged brain tissue.

RESULTS

The average performance score in the pigs of the ET-1 group was 9.67±1.03 and 9.00±1.26 respectively, at 24h and 72h after surgery, which was significantly higher than that of the pigs in sham group. The brain lesion percentage detected by MRI was 12.26±0.60%, and 10.33±0.51% respectively, at 24h and 72h after surgery in the ET-1 group. Microscopy showed extended pyknotic neuronal perikarya in neurons located in the ischemic area.

CONCLUSIONS

The endothelin-1 induced porcine cerebral ischemic model is technically easier, and able to create cerebral ischemia severe enough to cause a functional neurological deficit as well as observable lesions on MRI. It is a suitable model for long-term cerebral ischemia research.

Inhibitory effect of fentanyl citrate on the release of endothlin-1 induced by bradykinin in melanoma cells

BACKGROUND

Our previous study showed that the μ-opioid receptor agonist fentanyl citrate inhibits endothelin-1-and bradykinin-mediated pain responses in mice orthotopically inoculated with melanoma cells. We also demonstrated that bradykinin induces endothelin-1 secretion in melanoma cells. However, the analgesic mechanisms of fentanyl citrate remain unclear. Thus, the present study was conducted to determine whether fentanyl citrate affects bradykinin-induced endothelin-1 secretion in B16-BL6 melanoma cells.

METHODS

The amount of endothelin-1 in the culture medium was measured using an enzyme immunoassay. The expression of endothelin-1, kinin B₂ receptors, and μ-opioid receptors in B16-BL/6 melanoma cells was determined using immunocytochemistry.

RESULTS

Fentanyl citrate inhibited bradykinin-induced endothelin-1 secretion. The inhibitory effect of fentanyl citrate on the secretion of endothelin-1 was attenuated by the μ-opioid receptor antagonist naloxone methiodide. The immunoreactivities of endothelin-1, kinin B₂ receptors, and μ-opioid receptors in B16-BL6 melanoma cells were observed.

CONCLUSION

These results suggest that fentanyl citrate regulates bradykinin-induced endothelin-1 secretion through μ-opioid receptors in melanoma cells.

Effect of N-arachidonoyl-l-serine on human cerebromicrovascular endothelium

N-arachidonoyl-l-serine (ARA-S) is an endogenous lipid, chemically related to the endocannabinoid, N-arachidonoyl ethanolamine (i.e., anandamide) and with similar physiologic and pathophysiologic functions. Reports indicate that ARA-S possesses vasoactive and neuroprotective properties resembling those of cannabinoids. However, in contrast to cannabinoids, ARA-S binds weakly to its known classical receptors, CB1 and CB2, and is therefore considered to be a 'cannabinoid-like' substance. The originally described ARA-S induced-endothelial-dependent vasorelaxation was not abrogated by CB1, CB2 receptor antagonists or TRPV1 competitive inhibitor. The present report demonstrates that ARA-S enhances the fluorescence staining of both cannabinoid receptors (CB1 and CB2) in human brain endothelial cells (HBEC). This reaction is specific since it was reduced by respective selective receptor antagonist (SR141716A and SR141728A). ARA-S alone or in the presence of ET-1 was shown to alter the cytoskeleton (actin). Both ARA-S stimulated phosphorylation of various kinases (MAPK, Akt, JNK and c-JUN) and alteration of cytoskeleton are mediated via CB1, CB2 and TRPV1 receptors. The findings also showed the involvement of Rho/Rock and PI3/Akt/NO pathways in the ARA-S-induced phosphorylation of kinases and actin reorganization in HBEC. All of the above mentioned ARA-S-induced effects were reduced by the treatment with LY294002 (inhibitor of PI3/Akt kinase), except MAPK kinase. In addition, MAPK, JNK, c-JUN phosphorylation were inhibited by H1152 (inhibitor of Rho/ROCK kinase), except Akt kinase. Furthermore, PI3/Akt pathway was inhibited by pretreatment with l-NAME (inhibitor of NOS). The findings suggest that ARA-S is a modulator of Rho kinase and may play a critical role in the regulation of its activity and subsequent effects on the cytoskeleton and its role in supporting essential cell functions like vasodilation, proliferation and movement.

Endothelin-1-Induced Cell Hypertrophy in Cardiomyocytes is Improved by Fenofibrate: Possible Roles of Adiponectin

Aim: Previous studies demonstrated that endothelin-1 (ET-1) can significantly increase the cell size and stimulate adiponectin expression in cultured human cardiomyocytes (HCM). The aim of the present study was to investigate the effects of fenofibrate, a peroxisome proliferator-activated receptor-α (PPARα) activator, on cell hypertrophy and adiponectin expression in vitro and in a rat model of daunorubicin-induced cardiomyopathy.

Methods: The cultured human cardiomyocytes (HCM) were stimulated with or without ET-1. The cell size and the protein expressions of PPARα and adiponectin were tested by confocal Immunofluorescence study and Western blot, respectively. To study the effects of PPARα activation on ET-1-induced cell hypertrophy and adiponectin protein synthesis, HCM were pretreated with fenofibrate or small interfering RNA (siRNA) of PPARα. Echocardiographic parameters were measured and immunohistochemistry study of myocardial adiponectin expression was conducted in the in vivo study.

Results: ET-1 significantly increased the cell size, dose-dependently suppressed the expression of PPARα, and enhanced the expression of adiponectin; whereas, such an increase of cell size and enhancement of adiponectin expression were inhibited by the pre-treatment with fenofibrate. Addition of siRNA of PPARα abolished the effects of fenofibrate. Moreover, we found that fenofibrate treatment can significantly improve the left ventricular function and reverse the myocardial expression of adiponectin.

Conclusions: Our study shows that fenofibrate may protect against ET-1-induced cardiomyocyte hypertrophy and enhanced adiponectin expression through modulation of PPARα expression in vitro and limitation of daunorubicin cardiotoxicity in vivo, suggesting a novel mechanistic insight into the role of PPARα and adiponectin in cardiac hypertrophy and heart failure.

The effects of hydroxychloroquine on endothelial dysfunction

Hydroxychloroquine is an anti-malarial drug which, due to its anti-inflammatory and immunomodulatory effects, is widely used for the treatment of autoimmune diseases. In a model of systemic lupus erythematosus hydroxychloroquine has been shown to exert protective endothelial effects. In this study, we aimed to investigate whether hydroxychloroquine was endothelial protective in an in vitro model of TNF-α and preeclamptic serum induced dysfunction. We showed that hydroxychloroquine significantly reduced the production of TNF-α and preeclamptic serum induced endothelin-1 (ET-1). Hydroxychloroquine also significantly mitigated TNF-α induced impairment of angiogenesis. These findings support the further assessment of hydroxychloroquine as an adjuvant therapy in preeclampsia.

The heart as an extravascular target of endothelin-1 in particulate matter-induced cardiac dysfunction

Exposure to particulate matter air pollution has been causally linked to cardiovascular disease in humans. Several broad and overlapping hypotheses describing the biological mechanisms by which particulate matter exposure leads to cardiovascular disease have been explored, although linkage with specific factors or genes remains limited. These hypotheses may or may not also lead to particulate matter-induced cardiac dysfunction. Evidence pointing to autocrine/paracrine signaling systems as modulators of cardiac dysfunction has increased interest in the emerging role of endothelins as mediators of cardiac function following particulate matter exposure. Endothelin-1, a well-described small peptide expressed in the pulmonary and cardiovascular systems, is best known for its ability to constrict blood vessels, although it can also induce extravascular effects. Research on the role of endothelins in the context of air pollution has largely focused on vascular effects, with limited investigation of responses resulting from the direct effects of endothelins on cardiac tissue. This represents a significant knowledge gap in air pollution health effects research, given the abundance of endothelin receptors found on cardiac tissue and the ability of endothelin-1 to modulate cardiac contractility, heart rate, and rhythm. The plausibility of endothelin-1 as a mediator of particulate matter-induced cardiac dysfunction is further supported by the therapeutic utility of certain endothelin receptor antagonists. The present review examines the possibility that endothelin-1 release caused by exposure to PM directly modulates extravascular effects on the heart, deleteriously altering cardiac function.

Suppressed endothelin-1 by anti-VEGF therapy is important for patients with BRVO-related macular edema to improve their vision

Background

Branch retinal vein occlusion (BRVO) commonly occurs at the arteriovenous crossing in the unilateral eye, and cardiovascular diseases can be risk factors of BRVO. However, the pathomechanism leading to BRVO is not yet clear. In addition to mechanical compression, the vein might locally constrict due to an altered biochemical environment, such as an increase in the concentration of endothelin-1 (ET-1). We evaluated changes in ET-1 following injection of intravitreal bevacizumab (IVB), which is the anti-vascular endothelial growth factor (VEGF) agent with the longest serum half-life, to determine the effect on BRVO-related macular edema.

Methods

Twenty consecutive patients with BRVO-related macular edema (10 males, 10 females; age range 56–83 years) who visited our hospital were included in this prospective study. Visual acuity (VA); central retinal thickness (CRT), determined by macular optical coherence tomography (OCT); and plasma ET-1 levels were obtained before IVB treatment and 1 month later.

Results

Patients had hypertension (80 %), dyslipidemia (50 %), diabetes mellitus (35 %), or collagen disease (5 %). Mean CRT was significantly decreased from 673.0 ± 327.8 to 388.2 ± 155.0 μm (P = 0.0007), and mean VA was significantly improved after IVB (P = 0.0239). Mean plasma ET-1 was significantly decreased from 1.272 ± 0.451 to 1.095 ± 0.316 pg/mL (P = 0.0238); however, the plasma ET-1 level was increased in all five patients who did not show improved VA after IVB.

Conclusions

In patients with BRVO-related macular edema, anti-VEGF therapy leads to an expected reduction in ET-1 levels; however, the ET-1 level was found to increase in some patients; this is clearly related to less improvement of VA after anti-VEGF therapy.

Trial registration

University hospital Medical Information Network (UMIN) Center UMIN000013236. Registered 10 October, 2012.

Endothelin-1 (ET-1) induces resistance to bortezomib in human multiple myeloma cells via a pathway involving the ETB receptor and upregulation of proteasomal activity

PURPOSE

Bortezomib (BTZ) is used for the treatment of multiple myeloma (MM). However, a significant proportion of patients may be refractory to the drug. This study aimed to investigate whether the endothelin (ET-1) axis may act as an escape mechanism to treatment with bortezomib in MM cells.

METHODS

NCI-H929 and RPMI-8226 (human MM cell lines) were cultured with or without ET-1, BTZ, and inhibitors of the endothelin receptors. ET-1 levels were determined by ELISA, while the protein levels of its receptors and of the PI3K and MAPK pathways' components by western blot. Effects of ET-1 on cell proliferation were studied by MTT and on the ubiquitin proteasome pathway by assessing the chymotryptic activity of the 20S proteasome in cell lysates.

RESULTS

Endothelin receptors A and B (ETAR and ETBR, respectively) were found to be expressed in both cell lines, with the RPMI-8226 cells that are considered resistant to BTZ, expressing higher levels of ETBR and in addition secreting ET-1. Treatment of the NCI-H929 cells with ET-1 increased proliferation, while co-incubation of these cells with ET-1 and BTZ decreased BTZ efficacy with concomitant upregulation of 20S proteasomal activity. Si-RNA silencing or chemical blockade of ETBR abrogated the protective effects of ET-1. Finally, data suggest that the predominant signaling pathway involved in ET-1/ETBR-induced BTZ resistance in MM cells may be the MAPK pathway.

CONCLUSION

Our data suggest a possible role of the ET-1/ETBR axis in regulating the sensitivity of MM cells to BTZ. Thus, combining bortezomib with strategies to target the ET-1 axis could prove to be a novel promising therapeutic approach in MM.

Therapeutic potential of endothelin inhibitors in canine hemangiosarcoma

AIMS

Hemangiosarcoma (HSA) that originates from vascular endothelial cells is the most common splenic malignant neoplasm in dogs, as it accounts for approximately 20% of all canine soft tissue sarcomas. In this study, inhibitory effects of endothelin receptor antagonists on the growth of HSA cells were examined using cell lines established from canine HSA.

MAIN METHODS

The preproendothelin-1 (PPET-1), endothelin type A receptor (ETA) and endothelin type B receptor (ETB) mRNA expression levels in HSA cell lines (n=5) were analyzed quantitatively by real-time RT-PCR. These levels were compared with those in HSA tissues (n=11) and those in normal splenic tissues (n=6). ETA and ETB protein expression was examined by western blot. The production and secretion of endothelin-1 (ET-1) and big ET-1 by cell lines were analyzed by measuring the levels in the culture medium by ELISA. The inhibitory effects of endothelin receptor antagonists (ambrisentan, BQ788 and bosentan) on cell growth were evaluated by WST-8 assay.

KEY FINDINGS

The PPET1 and ETA mRNA expression levels were elevated in HSA tissues and HSA cell lines compared with normal tissues. In cell lines, the production of ET-1 and big ET-1 peptide as well as the expression of ETA protein were detected, but the levels of ETB were not measured. Ambrisentan and bosentan inhibited growth activity in cell lines. Ambrisentan was more effective than bosentan.

SIGNIFICANCE

These findings demonstrate the importance of the ETA axis in canine HSA as well as the potential of ETA inhibitors in the treatment of canine HSA.

Endothelin ETA receptors predominate in chronic thromboembolic pulmonary hypertension

AIMS

Endothelin-1 levels are raised in chronic thromboembolic pulmonary hypertension. Our aim in this study was to identify the presence of endothelin receptors in patients with CTEPH by analysing tissue removed at pulmonary endarterectomy.

MAIN METHODS

Pulmonary endarterectomy tissue cross-sections were analysed using autoradiography with [(125)I]-ET-1 using ligands selective for ETA or ETB to determine sub-type distribution. The precise cellular localisation of ETA and ETB receptors was determined using selective antisera to both sub-types and compared with haematoxylin and eosin, Elastic Van Gieson and smooth muscle actin labelled sections.

KEY FINDINGS

Two patterns of ET-1 binding were found. In sections with frequent recanalised channels, ET-1 bound to the smooth muscle cells surrounding the channels. In sections where there was less organised thrombus with no obvious re-canalisation, minimal ET-1 binding was observed. Some contractile type smooth muscle cells not associated with recanalised channels and diffusely spread throughout the PEA material were associated with ET receptor antibody binding on immunohistochemistry. There was a greater expression of the ETA receptor type in the specimens.

SIGNIFICANCE

The presence of ET-1 receptors in the chronic thrombus in proximal CTEPH suggests ET-1 could act not only on the distal vasculopathy in the unobstructed vessels but may also stimulate smooth muscle cell proliferation within chronic clot. The abundance of ET receptors within the tissue provides evidence that the ET pathway is involved in the pathology of chronic thrombus reorganisation leading to CTEPH providing a rationale for the repurposing of ET receptor antagonists in the treatment of this condition.

Endothelin receptor antagonists in sickle cell disease: A promising new therapeutic approach

Sickle cell disease (SCD) is a genetic hematologic disorder that is characterized by a variety of potentially life threatening acute and chronic complications. Currently, hydroxyurea is the only clinically approved pharmacological therapy for the treatment of SCD, and the continued prevalence of severe disease complications underscores the desperate need for the development of new therapeutic agents. Central features of the sickle cell disease milieu, including hypoxia, oxidative stress, and thrombosis, are established enhancers of endothelin-1 (ET-1) synthesis. This conceptual connection between ET-1 and SCD was confirmed by multiple studies that demonstrated markedly elevated plasma and urinary levels of ET-1 in SCD patients. Direct evidence for the involvement of ET-1 signaling in the development of SCD pathologies has come from studies using endothelin receptor antagonists in SCD mice. This review summarizes recent studies that have implicated ET-1 signaling as a mechanistic contributor to renal, vascular, pulmonary, and nociceptive complications of sickle cell disease and discusses the potential for the use of ET receptor antagonists in the treatment of SCD.

Targeting the ROS-HIF-1-endothelin axis as a therapeutic approach for the treatment of obstructive sleep apnea-related cardiovascular complications

Obstructive sleep apnea (OSA) is now recognized as an independent and important risk factor for cardiovascular diseases such as hypertension, coronary heart disease, heart failure and stroke. Clinical and experimental data have confirmed that intermittent hypoxia is a major contributor to these deleterious consequences. The repetitive occurrence of hypoxia-reoxygenation sequences generates significant amounts of free radicals, particularly in moderate to severe OSA patients. Moreover, in addition to hypoxia, reactive oxygen species (ROS) are potential inducers of the hypoxia inducible transcription factor-1 (HIF-1) that promotes the transcription of numerous adaptive genes some of which being deleterious for the cardiovascular system, such as the endothelin-1 gene. This review will focus on the involvement of the ROS-HIF-1-endothelin signaling pathway in OSA and intermittent hypoxia and discuss current and potential therapeutic approaches targeting this pathway to treat or prevent cardiovascular disease in moderate to severe OSA patients.

Gene expression profiling reveals novel protective effects of Aminaphtone on ECV304 endothelial cells

Aminaphtone, a drug used in the treatment of chronic venous insufficiency (CVI), showed a remarkable role in the modulation of several vasoactive factors, like endothelin-1 and adhesion molecules. We analysed in vitro the effects of Aminaphtone on whole-genome gene expression and production of different inflammatory proteins. ECV-304 endothelial cells were stimulated with IL-1β 100U/ml in the presence or absence of Aminaphtone 6μg/ml. Gene expression profiles were compared at 1, 3, and 6h after stimulation by microarray. Supernatants of ECV-304 cultures were analysed at 3, 6, 12, and 24h by multiplex ELISA for production of several cytokine and chemokines. Microarrays showed a significant down-regulation at all times of a wide range of inflammatory genes. Aminaphtone appeared also able to modulate the regulation of immune response process (down-regulating cytokine biosynthesis, transcripts involved in lymphocyte differentiation and cell proliferation, and cytokine-cytokine receptor interaction) and to regulate genes engaged in homeostasis, secretion, body fluid levels, response to hypoxia, cell division, and cell-to-cell communication and signalling. Results were confirmed and extended analysing the secretome, which showed significant reduction of the release of 14 cytokines and chemokines. These effects are predicted to be mediated by interaction with different transcription factors. Aminaphtone was able to modulate the expression of inflammatory molecules relevant to the pathogenesis of several conditions in which the endothelial dysfunction is the main player and early event, like scleroderma, lung fibrosis, or atherosclerosis.

Bone-marrow-derived mesenchymal stem cells attenuate cognitive deficits in an endothelin-1 rat model of stroke

PURPOSE

Stroke is the third leading cause of death and permanent disability in the United States, often producing long-term cognitive impairments, which are not easily recapitulated in animal models. The goals of this study were to assess whether: (1) the endothelin-1 (ET-1) model of chronic stroke produced discernable cognitive deficits; (2) a spatial operant reversal task (SORT) would accurately measure memory deficits in this model; and (3) bone-marrow-derived mesenchymal stem cells (BMMSCs) could reduce any observed deficits.

METHODS

Rats were given unilateral intracerebral injections of vehicle or ET-1, a stroke-inducing agent, near the middle cerebral artery. Seven days later, they were given intrastriatal injections of BMMSCs or vehicle, near the ischemic penumbra. The cognitive abilities of the rats were assessed on a novel SORT, which was designed to efficiently distinguish cognitive deficits from potential motoric confounds.

RESULTS

Rats given ET-1 had significantly more cognitive errors at six weeks post-stroke on the SORT, and that these deficits were attenuated by BMMSC transplants.

CONCLUSIONS

These findings indicate that: (1) the ET-1 model produces chronic cognitive deficits; (2) the SORT efficiently measures cognitive deficits that are not confounded by motoric impairment; and (3) BMMSCs may be a viable treatment for stroke-induced cognitive dysfunction.

Hypoxia-inducible factor-1α, vascular endothelial growth factor, inducible nitric oxide synthase, and endothelin-1 expression correlates with angiogenesis in congenital heart disease

In Taiwan, the average prevalence of congenital heart disease (CHD) is 13.08/1000 live births. Most children with CHD die before the age of 5 years; therefore, identifying treatment methods to extend the life of CHD patients is an important issue in clinical practice. The objective of this study is to evaluate the roles of hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF), inducible nitric oxide synthase (iNOS), endothelin-1 (ET-1), and CD34 in CHD autopsy cases in comparison with autopsy cases without CHD. The study included 19 autopsy cases, which were divided into the following four groups: acyanotic CHD (n = 11), cyanotic CHD (n = 3), CHD associated with chromosomal abnormalities (n = 3), and complex CHD (n = 2). Heart specimens obtained from 10 autopsy cases without CHD were included as controls. Our results indicated that high percentages of HIF-1α (100%), VEGF (89.5%), iNOS (78.9%), and ET-1 (84.2%) expressions were observed in CHD autopsy cases and this was found to be significant. HIF-1α induced by hypoxia could play a potential role in relating downstream gene expressions in CHD patients. Upregulation of VEGF by HIF-1α could play an important role in triggering angiogenesis to protect myocardial cell survival in a hypoxic microenvironment. Therefore, HIF-1α could be a significant prognosis marker in CHD and be a prospective candidate in the development of target therapy in cardiovascular diseases.

Endothelin-1: Biosynthesis, Signaling and Vasoreactivity

Endothelin-1 (ET-1) is an extremely potent vasoconstrictor peptide originally isolated from endothelial cells. Its synthesis, mainly regulated at the gene transcription level, involves processing of a precursor by a furin-type proprotein convertase to an inactive intermediate, big ET-1. The latter peptide can then be cleaved directly by an endothelin-converting enzyme (ECE) into ET-1 or reach the active metabolite through a two-step process involving chymase hydrolyzing big ET-1 to ET-1 (1-31), itself needing conversion to ET-1 by neprilysin (NEP) to exert physiological activity. ET-1 signals through two G protein-coupled receptors, endothelin receptor A (ETA) and endothelin receptor B (ETB). Both receptors induce an increase in intracellular Ca(2+), mainly from the extracellular space through voltage-independent mechanisms, the receptor-operated channels and store-operated channels. ET-1 also induces signaling through epidermal growth factor receptor transactivation, oxidative stress induction, rho-kinase, and the activation (ETA) or inhibition (ETB) of the adenylate cyclase/cyclic adenosine monophosphate pathway. Arterial vasoconstriction is mediated mainly by the ETA receptor. ET-1, via endothelium-located ETB, relaxes arteries or constricts vessels following activation of the same receptor type on the smooth muscle, where it can interact with ETA. In addition, ETB-dependent vasoconstriction seems more prominent in the venous vasculature. A better understanding of how ET-1 is synthesized and how ETA and ETB receptors interact could help design better pharmacological agents in the treatment of cardiovascular diseases where targeting the ET-1 system is indicated.

Transforming growth factor beta 1 induced endothelin-1 release is peroxisome proliferator-activated receptor gamma dependent in A549 cells

Background

Endothelin-1 (ET-1) is involved in pulmonary vascular remodeling. The aim of this study was to investigate the biochemical interactions between PPAR-γ, TGF-β1 and ET-1 in vitro.

Methods

A549 cells were pre-treated with S2505 (10 μM), S2871 (10 μM) with/without SB203580 (10 μM) for 60 min following 2 h treatment with 10 ng/mL TGF-β1. A549 cells were also transfected with positive or negative PPAR-γ plasmids for comparison. RT-PCR, ELISA, western blotting and confocal laser scanning microscopy (CLSM) were used to measure the relevant expression of mRNA, protein, mediators of pathways and nuclear factor translocation.

Results

SB203580 inhibited TGF-β1 induced ET-1 expression in A549 cells. S2871 decreased PPAR-γ mRNA and increase TGF-β1-induced ET-1 expression. S2871 increased phosphorylation of p38 MAPK and Smad2. Cells transfected with PPAR-γ negative plasmid increased TGF-β1 induced ET-1 expression, and increased the expression of phospho-p38 MAPK and phospho-Smad2. S2505 increased PPAR-γ mRNA expression, suppressed the increased TGF-β1-induced expression of ET-1. S2505 inhibited TGF-β1 induced phosphorylation of p38 MAPK and Smad2, also the nuclear translocation of Smad2. Cells transfected with PPAR-γ positive plasmid reduced TGF-β1-induced ET-1 expression, and inhibited the expression of phospho-p38 MAPK and phospho-Smad2.

Conclusions

TGF-β1 induced release of endothelin-1 is PPAR-γ dependent in cultured A549 cells.

Adrenomedullin and endothelin-1 are associated with myocardial injury and death in septic shock patients

Background

Adrenomedullin and endothelin-1 are hormones with opposing effects on the cardiovascular system. Adrenomedullin acts as a vasodilator and seems to be important for the initiation and continuation of the hyperdynamic circulatory response in sepsis. Endothelin-1 is a vasoconstrictor and has been linked to decreased cardiac performance. Few studies have studied the relationship between adrenomedullin and endothelin-1, and morbidity and mortality in septic shock patients. High-sensitivity troponin T (hsTNT) is normally used to diagnose acute cardiac injury but is also prognostic for outcome in intensive care. We investigated the relationship between mid-regional pro-adrenomedullin (MR-proADM), C-terminal pro-endothelin-1 (CT-proET-1), and myocardial injury, measured using transthoracic echocardiography and hsTNT in septic shock patients. We were also interested in the development of different biomarkers throughout the ICU stay, and how early measurements were related to mortality. Further, we assessed if a positive biomarker panel, consisting of MR-proADM, CT-proET-1, and hsTNT changed the odds for mortality.

Methods

A cohort of 53 consecutive patients with septic shock had their levels of MR-proADM, CT-proET-1, hsTNT, and left ventricular systolic functions prospectively measured over 7 days. The relationship between day 1 levels of MR-proADM/CT-proET-1 and myocardial injury was studied. We also investigated the relationship between biomarkers and early (7-day) and later (28-day) mortality. Likelihood ratios, and pretest and posttest odds for mortality were calculated.

Results

Levels of MR-proADM and CT-proET-1 were significantly higher among patients with myocardial injury and were correlated with left ventricular systolic dysfunction. MR-proADM and hsTNT were significantly higher among 7-day and 28-day non-survivors. CT-proET-1 was also significantly higher among 28-day but not 7-day non-survivors. A positive biomarker panel consisting of the three biomarkers increased the odds for mortality 13-fold to 20-fold.

Conclusions

MR-proADM and CT-proET-1 are associated with myocardial injury. A biomarker panel combining MR-proADM, CT-proET-1, and hsTNT increases the odds ratio for death, and may improve currently available scoring systems in critical care.

Lipopolysaccharide potentiates endothelin-1-induced proliferation of pulmonary arterial smooth muscle cells by upregulating TRPC channels

Lipopolysaccharide (LPS) and endothelin-1 (ET-1) are critical pathogenic factors in sepsis-induced pulmonary hypertension; however it is unknown whether they have a coordinated action in the pathogenesis of this disease. Here we found that although LPS did not change the contractility of rat pulmonary arterial smooth muscle cells (PASMCs) in response to ET-1, it significantly promoted ET-1-induced PASMC proliferation. Measurement of ET-1-evoked Ca(2+) transients in PASMCs showed that LPS dramatically enhanced Ca(2+) influx mediated by transient receptor potential canonical (TRPC) channels. LPS did not directly activate TRPC channels, instead it selectively upregulated the expression of TRPC3 and TRPC4 in pulmonary arteries. Small interfering RNA (siRNA) and chemical blockers against TRPC channels abolished LPS-induced PASMC proliferation. LPS-induced cell proliferation and TRPC expression was mediated by the Ca(2+)-dependent calcineurin/NFAT signaling pathway. We suggest that blocking TRPC channels could be an effective strategy in controlling pulmonary arterial remodeling after endotoxin exposure.

Hydrogen Gas Ameliorates Hepatic Reperfusion Injury After Prolonged Cold Preservation in Isolated Perfused Rat Liver

Hydrogen gas reduces ischemia and reperfusion injury (IRI) in the liver and other organs. However, the precise mechanism remains elusive. We investigated whether hydrogen gas ameliorated hepatic I/R injury after cold preservation. Rat liver was subjected to 48-h cold storage in University of Wisconsin solution. The graft was reperfused with oxygenated buffer with or without hydrogen at 37° for 90 min on an isolated perfusion apparatus, comprising the H₂ (+) and H₂ (-) groups, respectively. In the control group (CT), grafts were reperfused immediately without preservation. Graft function, injury, and circulatory status were assessed throughout the perfusion. Tissue samples at the end of perfusion were collected to determine histopathology, oxidative stress, and apoptosis. In the H₂ (-) group, IRI was indicated by a higher aspartate aminotransferase (AST), alanine aminotransferase (ALT) leakage, portal resistance, 8-hydroxy-2-deoxyguanosine-positive cell rate, apoptotic index, and endothelial endothelin-1 expression, together with reduced bile production, oxygen consumption, and GSH/GSSG ratio (vs. CT). In the H₂ (+) group, these harmful changes were significantly suppressed [vs. H₂ (-)]. Hydrogen gas reduced hepatic reperfusion injury after prolonged cold preservation via the maintenance of portal flow, by protecting mitochondrial function during the early phase of reperfusion, and via the suppression of oxidative stress and inflammatory cascades thereafter.

Cerebrovascular disease in ageing and Alzheimer's disease

Cerebrovascular disease (CVD) and Alzheimer’s disease (AD) have more in common than their association with ageing. They share risk factors and overlap neuropathologically. Most patients with AD have Aβ amyloid angiopathy and degenerative changes affecting capillaries, and many have ischaemic parenchymal abnormalities. Structural vascular disease contributes to the ischaemic abnormalities in some patients with AD. However, the stereotyped progression of hypoperfusion in this disease, affecting first the precuneus and cingulate gyrus, then the frontal and temporal cortex and lastly the occipital cortex, suggests that other factors are more important, particularly in early disease. Whilst demand for oxygen and glucose falls in late disease, functional MRI, near infrared spectroscopy to measure the saturation of haemoglobin by oxygen, and biochemical analysis of myelin proteins with differential susceptibility to reduced oxygenation have all shown that the reduction in blood flow in AD is primarily a problem of inadequate blood supply, not reduced metabolic demand. Increasing evidence points to non-structural vascular dysfunction rather than structural abnormalities of vessel walls as the main cause of cerebral hypoperfusion in AD. Several mediators are probably responsible. One that is emerging as a major contributor is the vasoconstrictor endothelin-1 (EDN1). Whilst there is clearly an additive component to the clinical and pathological effects of hypoperfusion and AD, experimental and clinical observations suggest that the disease processes also interact mechanistically at a cellular level in a manner that exacerbates both. The elucidation of some of the mechanisms responsible for hypoperfusion in AD and for the interactions between CVD and AD has led to the identification of several novel therapeutic approaches that have the potential to ameliorate ischaemic damage and slow the progression of neurodegenerative disease.

A combination of the main constituents of Fufang Xueshuantong Capsules shows protective effects against streptozotocin-induced retinal lesions in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Fufang Xueshuantong Capsule, an herbal formula licensed for clinical use in China, which is composed of Panax notoginseng (Burkill) F.H. Chen, Salvia miltiorrhiza Bunge, Astragalus membranaceus (Fisch.) Bunge, and Scrophularia ningpoensis Hemsl, has proven effective for the treatment of diabetic retinopathy. However, its bioactive constituents are still ambiguous. In this study, the therapeutic effects of a combination of the main constituents of Fufang Xueshuantong Capsule (cFXT) were evaluated in streptozotocin (STZ)-induced retinal lesions to identify the bioactive constituents.

METHODS

Sprague-Dawley rats, except for those in the control group (vehicle+vehicle), were administered a single injection of 60mg/kg STZ. One-week later, STZ-treated rats were randomly divided into three groups-one STZ group (STZ+vehicle) and two cFXT treatment groups (STZ+cFXT). The rats in the latter two groups received cFXT 44.8mg/kg or cFXT 22.4mg/kg by intragastric gavage once per day, for 24 consecutive weeks. The rats in the control and STZ groups received the vehicle in the same way. Body weights and fasting blood glucose levels were recorded every four weeks. After treatment, hemorheological tests were performed to record the erythrocyte aggregation indexes, blood viscosity, and plasma viscosity. The trypsin digestion method was used to observe pericyte and acellular capillary counts in the retina. Ultraviolet spectrophotometry was utilized to measure the activity of aldose reductase (AR) by measuring the nicotinamide adenine dinucleotide phosphate (NADPH) consumption at 340nm. An immunohistochemical assay was used to observe the expressions of vascular endothelial growth factor (VEGF) and pigment epithelium-derived factor (PEDF) in the retina. The expression levels of intercellular adhesion molecule-1 (ICAM-1), endothelin-1 (RT-1),and occludin in the retina were tested by the western blot assay.

RESULTS

cFXT is composed of 991.44mg/g saponins of Panax notoginseng, 1.62mg/g harpagoside, 0.70mg/g cryptotanshinone, 0.74mg/g tanshinone I, and 5.50mg/g astragaloside A. Although it showed no effects on the increased body weight and blood glucose levels induced by STZ in rats. However, it showed a tendency to attenuate the increase in erythrocyte aggregation, plasma viscosity, and acellular vessel and pericyte loss, paralleled with a reversal of the hyper-activation of AR, the hyper-expression of VEGF, ICAM-1, and ET-1, and the hypo-expression of PEDF and occludin in the retinas of STZ-treated rats.

CONCLUSION

The saponins of Panax notoginseng, harpagoside, cryptotanshinone, tanshinone I, and astragaloside A are the main bioactive constituents of Fufang Xueshuantong Capsule and contribute to the attenuation of STZ-induced retinal lesions in rats. These constituents can be used as the base to optimize a new drug for the treatment of diabetic retinopathy, and can be selected for quality control of Fufang Xueshuantong Capsules.

Endothelin-1 protects human melanocytes from UV-induced DNA damage by activating JNK and p38 signalling pathways

Endothelin-1 is a paracrine factor with mitogenic, melanogenic and survival effects on cultured human melanocytes. We report that endothelin-1 signalling reduced the generation and enhanced the repair of ultraviolet radiation (UV)-induced DNA photoproducts, and inhibited apoptosis of human melanocytes, without increasing cAMP levels, melanin content or proliferation. Treatment with endothelin-1 activated the MAP kinases JNK and p38, as evidenced by phosphorylation of their target, activating transcription factor-2 (ATF-2). Endothelin-1 also enhanced the phosphorylation of JNK, p38 and ATF-2 by UV. The effects of endothelin-1 were dependent on increasing intracellular calcium mobilization by endothelin B receptor signalling. Activation of both JNK and p38 was required for reducing DNA photoproducts, but only JNK partially contributed to the survival effect of endothelin-1. ATF-2 activation depended mainly on JNK, yet was not sufficient for the effect of endothelin-1 on UV-induced DNA damage, suggesting the requirement for other JNK and p38 targets for this effect. Our results underscore the significance of endothelin-1 and endothelin B receptor signalling in reducing the genotoxic effects of UV via activating JNK and p38, hence restoring genomic stability of melanocytes.

c-Src tyrosine kinase mediates high glucose-induced endothelin-1 expression

Endothelin-1 (ET-1) plays an important role in the pathophysiology of diabetes-associated cardiovascular disorders. The molecular mechanisms leading to ET-1 upregulation in diabetes are not entirely defined. c-Src tyrosine kinase regulates important pathophysiological aspects of vascular response to insults. In this study, we aimed to elucidate whether high glucose-activated c-Src signaling plays a role in the regulation of ET-1 expression. Human endothelial cells EAhy926 (ECs) were exposed to normal or high levels of glucose for 24h. Male C57BL/6J mice were rendered diabetic with streptozotocin and then treated with a specific c-Src inhibitor (Src I1) or c-Src siRNA. Real-time PCR, Western blot, and ELISA, were used to investigate ET-1 regulation. The c-Src activity and expression were selectively downregulated by pharmacological inhibition and siRNA-mediated gene silencing, respectively. High glucose dose-dependently up-regulated c-Src phosphorylation and ET-1 gene and protein expression levels in human ECs. Chemical inhibition or silencing of c-Src significantly decreased the high-glucose augmented ET-1 expression in cultured ECs. In vivo studies showed significant elevations in the aortic ET-1 mRNA expression and plasma ET-1 concentration in diabetic mice compared to non-diabetic animals. Treatment with Src I1, as well as in vivo silencing of c-Src, significantly reduced the upregulated ET-1 expression in diabetic mice. These data provide new insights into the regulation of ET-1 expression in endothelial cells in diabetes. Pharmacological targeting of c-Src activity and/or expression may represent a potential therapeutic strategy to reduce ET-1 level and to counteract diabetes-induced deleterious vascular effects.

Plasma endothelin-1 level as a predictor for poor collaterals in patients with ≥95% coronary chronic occlusion

BACKGROUND

Coronary collateral circulation (CCC) plays an important role in protecting myocardium from ischemic damage. The studies on factors which impact on CCC might be of great clinical interest. The aim of the present study was to evaluate endothelin-1 (ET-1) as a potential predictor for poor or good CCC in patients with angiography-proven ≥95% coronary occlusion.

METHODS

We screened 1038 consecutive patients with ≥95% occlusion in at least one major epicardial coronary artery detected by coronary angiography. Of these, 663 patients were classified into the poor CCC group with Rentrop 0-2 grade collateral circulation and 375 patients into the good CCC group with Rentrop 3 grade. The association of plasma ET-1 levels with collateral status was assessed.

RESULTS

We found that patients in the poor CCC group had a higher ET-1 level than those in the good CCC group (0.59±0.48 vs. 0.39±0.32pmol/L, p<0.001), and the ET-1 values increased with the descent of the Rentrop grades (p for trend<0.001). Moreover, multivariate logistic regression analysis revealed an independent association between ET-1 and collateral status (odds ratio [95% CI] for poor CCC 2.27 [1.60-3.22], p<0.001). Additionally, the association presented significance in both men (odds ratio [95% CI] for poor CCC 3.18 [2.20-4.74], p<0.001) and women (odds ratio [95% CI] for poor CCC 3.10 [1.36-7.85], p=0.011) when the sex-specific analysis was performed.

CONCLUSIONS

Plasma ET-1 level may be a useful, easily available marker for predicting the degree of CCC in patients with ≥95% coronary chronic occlusion.

The Evaluation of Endothelin-1 and Endothelin Receptor Type A Gene Polymorphisms in Patients with Vitiligo

Background:

Endothelin-1 (EDN1) and EDN receptor type A (EDNRA) are implicated in melanocyte functions.

Aim and Objectives:

This study examines the role of EDN1 (G5665T and T-1370G) and EDNRA (C + 70G and G-231A) polymorphisms as a risk factor for vitiligo, and evaluates the relationship between genotypes and clinical characteristics of vitiligo patients.

Materials and Methods:

We analyzed genotype/allele distributions of EDN1 and EDNRA polymorphisms in 100 patients with vitiligo and 185 healthy controls by real-time polymerase chain reaction.

Results:

There was no notable risk for vitiligo afflicted by studied polymorphisms. However, the presence of EDNRA +70 variant G allele was found to be related with decreased risk for development of generalized type of vitiligo (odds ratio [OR]: 0.42, 95% confidence interval [CI] = 0.21–0.86, p_corr = 0.03) and showed protective effect against associated diseases seen in vitiligo (OR: 0.49, 95% CI = 0.27–0.88, p_corr = 0.034). Haplotype analysis demonstrated a strong (disequilibrium coefficient = 0.73, r² = 0.405) linkage disequilibrium between EDN1 G5665T and T-1370G polymorphisms. The EDN1 5665/-1330 TT haplotype was over represented significantly in controls than in patients (P = 0.04).

Conclusion:

The studied polymorphisms do not seem to be a major risk for vitiligo. Haplotype analysis denoting protective effects against vitiligo may indicate an indirect interaction in the course of vitiligo. In addition, EDNRA + 70 polymorphism is protective against generalized type of vitiligo and associated diseases.

Human tissue kallikrein ameliorates cerebral vasospasm in a rabbit model of subarachnoid hemorrhage

OBJECTIVES

Cerebral vasospasm (CVS) and early brain injury are major causes of morbidity and mortality following subarachnoid hemorrhage (SAH). We investigated the efficiency of human tissue kallikrein (HTK) to prevent CVS in a rabbit model of SAH.

METHODS

Forty-eight Japanese white rabbits were randomly divided into four groups (n = 12 each): control (sham-operated), SAH, SAH + phosphate-buffered saline (PBS, vehicle), and SAH + HTK. Basilar artery (BA) diameters were measured by three-dimensional computed tomography angiography at three time points. Endothelin-1 (ET-1) and nitric oxide (NO) levels in the cerebrospinal fluid (CSF) were assayed 24 h before and 5 and 7 days after SAH. After the last measurement, the animals were killed, and endothelial cell apoptosis was assessed. Bax and Bcl-2 levels in the BA were measured by western blotting.

RESULTS

HTK was found to significantly reduce CVS following SAH in rabbits. Inverse changes were observed in ET-1 and NO levels in the CSF collected from the SAH group. HTK increased levels of NO, which has a vasodilatory effect, but did not affect levels of ET-1, which has a vasoconstrictive effect. CTA revealed that HTK treatment significantly increased BA diameter. Moreover, HTK treatment reduced the number of apoptotic cells following SAH, presumably by increasing and decreasing Bcl-2 and Bax expression, respectively.

CONCLUSION

HTK ameliorated CVS and inhibited apoptosis in the BA in a rabbit model of SAH.

Urinary fibrogenic cytokines ET-1 and TGF-β1 are associated with urinary angiotensinogen levels in obese children

BACKGROUND

Fibrogenic cytokines are recognized as putative drivers of disease activity and histopathological deterioration in various kidney diseases. We compared urinary transforming growth factor β1 (U-TGF-β1) and endothelin 1 (U-ET-1) levels across body mass index classes and assessed their association with the level of urinary angiotensinogen (U-AGT), a biomarker of intrarenal renin-angiotensin-aldosterone system (RAAS).

METHODS

The was a cross-sectional evaluation of 302 children aged 8-9 years. Ambulatory blood pressure (BP), insulin resistance (HOMA-IR), aldosterone level and renal function were evaluated. U-ET-1, U-TGF-β1 and U-AGT levels were determined by immunoenzymatic methods.

RESULTS

Obese children presented with the lowest levels of U-ET-1 and U-TGF-β1, but the difference was only significant for U-ET-1. In obese children, the median levels of both U-ET-1 and U-TGF-β1 tended to increase across tertiles (T1-T3) of U-AGT (U-ET-1: T1, 19.9 (14.2-26.3); T2, 32.5 (23.3-141.6); T3, 24.8 (18.7-51.5) ng/g creatinine, p = 0.007; U-TGF-β1: T1, 2.2 (1.8-4.0); T2, 4.3 (2.7-11.7); T3, 4.9 (3.8-10.1) ng/g creatinine, p = 0.004]. In multivariate models, in the obese group, U-ET-1 was associated with HOMA-IR and aldosterone and U-AGT levels, and U-TGF-β1 was associated with U-AGT levels and 24 h-systolic BP.

CONCLUSIONS

Whereas the initial hypothesis of higher levels of urinary fibrogenic cytokines in obese children was not confirmed in our study, both TGF-β1 and U-ET-1 levels were associated with U-AGT level, which likely reflects an early interplay between tissue remodeling and RAAS in obesity-related kidney injury.

Endothelin-1 as a predictor of impaired glucose tolerance and type 2 diabetes--A longitudinal study in the Vara-Skövde Cohort

We addressed whether endothelin-1, a marker of endothelial dysfunction, predicts impaired glucose tolerance (IGT) and type 2 diabetes mellitus (T2DM) in a population study in south-western Sweden. Follow-up after 9.7 years showed an association between circulating endothelin-1 levels at baseline and development of IGT/T2DM in women but not in men.

[Circuit resistance training improved endothelial dysfunction in obese aged women]

INTRODUCTION

It is widely accepted that obesity is associated with endothelial dysfunction. In a recent paper, we have also found circuit resistance training may reduce visceral fat in obese aged women. Accordingly, the current study was conducted to ascertain the effects of circuit resistance training on markers of endothelial dysfunction in this population group.

METHODS

In the present interventional study, a total of 48 obese aged women were recruited from the community. Twenty-four of them were randomly assigned to perform a 12-week resistance circuit training programme, 3-days per week. This training was circularly performed in 6 stations: arm curl, leg extension, seated row, leg curl, triceps extension and leg press. The Jamar handgrip electronic dynamometer was used to assess maximal handgrip strength of the dominant hand. Lastly, serum samples were analysed using an immunoassay (ELISA) for endothelin-1, intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1).

RESULTS

When compared to baseline, resistance training significantly reduced serum levels of endothelin-1 (2.28 ± 0.7 vs. 1.98 ± 1.1 pg/ml; p = 0.019; d = 0.67) and ICAM-1 (290 ± 69 vs. 255 ± 76 ng/ml; p = 0.004; d = 0.92) in the experimental group. No significant changes in any of the tested outcomes were found in the control group.

CONCLUSION

A short-term circuit resistance program improved endothelial dysfunction in aged obese women. Further studies on this topic are still required to consolidate this approach in clinical application.

ETA and ETB receptors contribute to neuropeptide Y-induced secretion of endothelin-1 in right but not left human ventricular endocardial endothelial cells

Our recent work showed that neuropeptide Y-induced secretion of endothelin-1 (ET-1) in left and right human ventricular endocardial endothelial cells (hLEECs or hREECs respectively) via the activation of neuropeptide Y2 or Y5 receptors depending on the cell type. The aim of this study was to verify whether hLEECs or hREECs secretion of ET-1 induced by NPY is due, in part, to the activation of ETA and/or ETB receptors by the secreted ET-1. Using the technique of indirect immunofluorescence coupled to real 3-D confocal microscopy, as well as ELISA, our results show that in hREECs, the NPY-induced release of ET-1 seems to be due, in part, to the activation of both ETA and ETB receptors. On the other hand, in hLEECs, ETA and ETB receptors do not contribute to the ET-1 released by NPY. Therefore, our results suggest that the NPY-induced release of ET-1 in EECRs is due to NPY receptor activation and the subsequent activation of the ETA and ETB receptors by the released ET-1. However, the release of ET-1 by NPY in hLEECs is mainly due to NPY receptor activation. Furthermore, this secretory process of ET-1 is different between the right and left ventricular cells and highlights the important tuning roles that right and left ventricular EECs possess as well as their contribution to the physiological and pathophysiological states of the underlying heart muscle.

Study of breakthrough cancer pain in an animal model induced by endothelin-1

Cancer patients with bone metastases often suffer breakthrough pain. However, little progress has been made in the treatment of breakthrough pain and its associated mechanism(s) in the patient with cancer due to lacking of resembling and predictive animal models. We previously have demonstrated that endothelin-1 plays an important role in breakthrough cancer pain. In the present study, we have established an animal model of breakthrough cancer pain induced by endothelin-1. The animal model of breakthrough cancer pain is strictly followed the definition and meets the characteristics of breakthrough pain. The model is reliable, reproducible and easy to be produced. To our knowledge, this is the first report for establishing such an animal model. In addition, we also found that a selective ETA receptor antagonist BQ-123 could reverse endothelin-1 induced breakthrough pain. We further studied the characteristics of pain behaviors such as hind limb use score and voluntary wheel running as well as the electrophysiology of sciatic nerve fibers with the model. The murine model shows high resemblance compared to the breakthrough cancer pain in the patients with cancer clinically. It provides a platform for further study of the pathogenesis of breakthrough cancer pain and targeted intervention.

Macitentan blocks endothelin-1 receptor activation required for chemoresistant ovarian cancer cell plasticity and metastasis

AIMS

In epithelial ovarian cancer (EOC), activation of endothelin-1 (ET-1)/endothelin A receptor (ETAR) and ET-1/ETBR signaling is linked to many tumor promoting effects, such as proliferation, angiogenesis, invasion, metastasis and chemoresistance. Understanding how to hamper the distinct mechanisms that facilitate epithelial plasticity and propagation is therefore central for improving the clinical outcome for EOC patients.

MAIN METHODS

The phosphorylation status of Akt and MAPK was evaluated by immunoblotting in A2780 and 2008 EOC cell lines and their cisplatinum-resistant variants. Vasculogenic mimicry was analyzed by vascular tubules formation assay. Tumor growth and metastases inhibition was performed in chemoresistant EOC xenografts.

KEY FINDINGS

We found that the dual ETAR/ETBR antagonist macitentan was able to inhibit the ET-1-induced activation of Akt and MAPK signaling pathways in chemoresistant EOC cells. Moreover, chemoresistant EOC cells displayed higher capability to engage vasculogenic mimicry compared to sensitive cells that was inhibited after treatment with macitentan. Finally, the specific ETAR antagonist zibotentan was less efficacious compared to macitentan to suppress tumor growth in chemoresistant EOC xenografts and the co-treatment of macitentan and cisplatinum reduced the metastatic progression.

SIGNIFICANCE

Our findings better clarify the ET-1-induced molecular mechanisms underlying the aggressive behavior of chemoresistant EOC cells. These results also support the use of macitentan in combination with chemotherapy as a rational therapeutic strategy for circumventing drug resistance in EOC.

Increased mortality with elevated plasma endothelin-1 in acute heart failure: an ASCEND-HF biomarker substudy

AIMS

Endothelin-1 (ET-1) is an endogenous vasoconstrictor implicated in pulmonary and systemic hypertension, as well as ventricular dysfunction, through effects on vascular smooth muscle, the kidneys, and cardiomyocytes. We aimed to determine the association between serial ET-1 levels and acute heart failure patient outcomes.

METHODS AND RESULTS

We measured plasma ET-1 at baseline, 48-72 h, and 30 days in a cohort of 872 patients hospitalized with acute heart failure from the ASCEND-HF trial (randomized to nesiritide vs. placebo), and its association with 30-day mortality, 180-day mortality, in-hospital death or worsening heart failure, and 30-day mortality or rehospitalization. Median ET-1 was 7.6 [interquartile range (IQR) 5.9-10] pg/mL at baseline, 6.3 (IQR 4.9-8.1) pg/mL at 48-72 h, and 5.9 (IQR 4.7-7.9) pg/mL at 30 days (P < 0.001). Baseline and 48-72 h ET-1 were found to be independently associated with 180-day mortality in a multivariable analysis [hazard ratio (HR) 1.6, 95% confidence interval (CI) 1.3-2.0, P < 0.001 and HR 1.5, 95% CI 1.2-1.9, P = 0.001, respectively, log-transformed]. ET-1 that was measured at 48-72 h was also independently associated with death or worsening heart failure prior to discharge [odds ratio (OR) 1.6, 95% CI 1.03-2.4, P = 0.03]. These independent associations remained significant after including NT-proBNP in the multivariable analysis.

CONCLUSIONS

We observed an independent association between elevated ET-1 and short-term in-hospital clinical outcomes and 180-day mortality in hospitalized patients with acute heart failure ET-1 provided additional prognostic information which was incremental to that yielded by NT-proBNP.

Elevations in C-reactive protein and endothelin-1 system activity in humans

AIMS

C-reactive protein (CRP) is an inflammatory cytokine that has been shown to be an independent predictor of future atherothrombotic events. Hyperactivity of endothelin-1 (ET-1), a potent vasoconstrictor peptide produced by the endothelium, is linked with cardiovascular disease development and progression. ET-1 is sensitive to inflammatory stimuli, though the influence of CRP on ET-1 system activity is unknown. We tested the hypothesis that ET-1-mediated vasoconstrictor tone is enhanced in adults with elevated plasma CRP concentrations.

MATERIALS AND METHODS

Sixty non-obese adults (43-70years) were studied: 20 with hsCRP<1.0mg/L (low CRP; 0.5±0.1mg/L); 20 with hsCRP 1.0-3.0mg/L (moderate CRP; 2.0±0.1mg/L); and 20 with hsCRP>3.0mg/L (high CRP; 6.3±0.5mg/L). Forearm blood flow (FBF; plethysmography) was determined in response to intra-arterial infusions of ET-1 (5pmol/min for 20min) and selective ETA receptor blockade (BQ-123, 100nmol/min for 60min).

KEY FINDINGS

In response to ET-1, FBF decreased ~10% in the low (-10.0±2.3%), moderate (-10.7±4.0%), and high (-6.6±5.2%) CRP groups, with no significant differences between groups. Additionally, all groups demonstrated a marginal, though significant (~10%), vasodilator response to BQ-123; however, there were no differences in the FBF response to BQ-123 across CRP groups. There were no significant correlations between plasma CRP concentrations and peak FBF response to either ET-1 or BQ-123.

SIGNIFICANCE

These results indicate that ET-1 system activity is not influenced by elevations in CRP. Enhanced ET-1 system activity may not be involved in the increased cardiovascular disease risk associated with elevations in plasma CRP concentrations.

Novel 24-h ovine model of brain death to study the profile of the endothelin axis during cardiopulmonary injury

BACKGROUND

Upregulation of the endothelin axis has been observed in pulmonary tissue after brain death, contributing to primary graft dysfunction and ischaemia reperfusion injury. The current study aimed to develop a novel, 24-h, clinically relevant, ovine model of brain death to investigate the profile of the endothelin axis during brain death-associated cardiopulmonary injury. We hypothesised that brain death in sheep would also result in demonstrable injury to other transplantable organs.

METHODS

Twelve merino cross ewes were randomised into two groups. Following induction of general anaesthesia and placement of invasive monitoring, brain death was induced in six animals by inflation of an extradural catheter. All animals were supported in an intensive care unit environment for 24 h. Animal management reflected current human donor management, including administration of vasopressors, inotropes and hormone resuscitation therapy. Activation of the endothelin axis and transplantable organ injury were assessed using ELISA, immunohistochemistry and standard biochemical markers.

RESULTS

All animals were successfully supported for 24 h. ELISA suggested early endothelin-1 and big endothelin-1 release, peaking 1 and 6 h after BD, respectively, but there was no difference at 24 h. Immunohistochemistry confirmed the presence of the endothelin axis in pulmonary tissue. Brain dead animals demonstrated tachycardia and hypertension, followed by haemodynamic collapse, typified by a reduction in systemic vascular resistance to 46 ± 1 % of baseline. Mean pulmonary artery pressure rose to 186 ± 20 % of baseline at induction and remained elevated throughout the protocol, reaching 25 ± 2.2 mmHg at 24 h. Right ventricular stroke work increased 25.9 % above baseline by 24 h. Systemic markers of cardiac and hepatocellular injury were significantly elevated, with no evidence of renal dysfunction.

CONCLUSIONS

This novel, clinically relevant, ovine model of brain death demonstrated that increased pulmonary artery pressures are observed after brain death. This may contribute to right ventricular dysfunction and pulmonary injury. The development of this model will allow for further investigation of therapeutic strategies to minimise the deleterious effects of brain death on potentially transplantable organs.

Urocortin 1 expression and secretion by human umbilical vein endothelial cells: In vitro effects of interleukin 8, interferon γ, lipopolysaccharide, endothelin 1, prostaglandin F-2α, estradiol, progesterone and dexamethasone

Urocortin 1 (Ucn1) is a 40-amino-acid peptide that has vasodilatory activity and displays immunomodulatory and antioxidant properties. Maternal and cord plasma Ucn1 levels are increased in preeclampsia and preterm labor, but the mechanisms of such increase are poorly known. Thus, we investigated Ucn1 localization in human umbilical cord and assessed some potential stimuli to Ucn1 release by human umbilical vein endothelial cells (HUVEC). Human umbilical cords were obtained at uncomplicated term pregnancy (n=11). Ucn1 localization was assessed by immunohistochemistry and quantified. HUVEC were grown in vitro to confluence, then incubated with serial concentrations of interleukin (IL)-8, interferon (INF)-γ, lipopolysaccharide (LPS), endothelin (ET)-1, prostaglandin (PG)F-2α, estradiol, progesterone and dexamethasone and Ucn1 concentrations were measured in the supernatants. Ucn1 was immunolocalized with similar intensity in umbilical cord arteries, vein and Wharton's jelly. Ucn1 mRNA was detected in all HUVEC cultures and Ucn1 peptide was detectable in culture medium from untreated cells at different time points. Incubation with IFN-γ increased Ucn1 secretion in a dose-dependent manner. Treatments with IL-8, LPS, ET-1 and dexamethasone were able to increase three to fourfold Ucn1 release from cultured endothelial cells. In conclusion, umbilical vessels express Ucn1 and may be a contributive source of Ucn1 release into fetal-placental circulation. IL-8, IFN-γ, LPS, ET-1 and dexamethasone promote Ucn1 secretion from cultured HUVEC.

A novel role of endothelium in activation of latent pro-membrane type 1 MMP and pro-MMP-2 in rat aorta

AIMS

Aortic stiffness is an independent risk factor for progression of cardiovascular diseases. Degradation of elastic fibres in aorta due to angiotensin II (ANGII)-stimulated overactivation of latent membrane type 1 matrix metalloproteinase (MT1MMP) and matrix metalloproteinase-2 (MMP2) is regarded to represent an important cause of aortic stiffness. Therefore, clarification of the causal mechanisms triggering the overactivation of these MMPs is of utmost importance. This study addresses the endothelium as a novel key activator of latent pro-MT1MMP and pro-MMP2 in rat aorta.

METHODS AND RESULTS

Using a co-culture model of rat aortic endothelial cells (ECs) and smooth muscle cells (SMCs), we found that ANGII stimulation resulted in activation of latent pro-MT1MMP and pro-MMP2 in SMCs exclusively when co-cultured with ECs (assessed with western blot and gelatin zymography, respectively). EC-specific AT1 receptor stimulation triggered endothelin-1 release and paracrine action on SMCs. Endothelin-1 increased expression and activity of pro-protein convertase furin in SMCs via endothelin receptor type A (assessed with qPCR and furin activity assay, respectively). Consequently, furin acted in two ways. First, it increased the activation of latent pro-MT1MMP and, second, it activated pro-αvβ3 integrin. Both pathways led to overactivation of latent pro-MMP2. In vitro findings in the co-culture model were fully consistent with the ex vivo findings obtained in isolated rat aorta.

CONCLUSIONS

We propose that the endothelium under ANGII stimulation acts as a novel and key activator of latent pro-MT1MMP and pro-MMP2 in SMCs of rat aorta. Therefore, endothelium may critically contribute to pathophysiology of aortic stiffness.

The G protein estrogen receptor (GPER) is regulated by endothelin-1 mediated signaling in cancer cells

Endothelin-1 (ET-1) is a potent endogenous vasoconstrictor involved in many diseases, including certain cardiovascular disorders and cancer. As previous studies have shown that the G protein estrogen receptor (GPER) may regulate ET-1 dependent effects on the vascular system, we evaluated whether GPER could contribute to the effects elicited by ET-1 in breast cancer and hepatocarcinoma cells. Here, we demonstrate that ET-1 increases GPER expression through endothelin receptor A (ETAR) and endothelin receptor B (ETBR) along with the activation of PI3K/ERK/c-Fos/AP1 transduction pathway. In addition, we show that GPER is involved in important biological responses observed upon ET-1 exposure, as the migration of the aforementioned tumor cells and the formation of tube-like structures in human umbilical vein endothelial cells (HUVECs). Our data suggest that GPER may contribute to ET-1 action toward the progression of some types of tumor.

Is adalimumab protective in ischemia-reperfusion injury in lung?

OBJECTIVES

Increasing cytokines and reactive oxygen species (ROS) during ischemia reperfusion (I-R) leads to the lung damage. Adalimumab (Ada) is a potent tumor necrosis factor-alpha (TNF-α) inhibitor agent. We aimed to evaluate whether Ada would prevent the lung tissue from damage development over the I-R process.

MATERIALS AND METHODS

Twenty seven Wistar albino male rats were divided into three groups (each group had 9 rats). To the control group, only laparotomy procedure was carried out. For I-R group, first infrarenal abdominal aorta was cross-clamped during 2 hr, and then reperfusion was performed for 2 hr. To I-R+Ada group, first a single dose of 50 mg/kg Ada was given intraperitoneally and 5 days later, same I-R procedure was carried out.

RESULTS

Levels of TNF-α, malondialdehyde (MDA), myeloperoxidase (MPO), endothelin-1 (ET-1) and caspase-3 enzyme activity of I-R group were higher than that of both I-R+ Ada [TNF-α (P=0.021), MDA (P=0.029), MPO (P=0.012), ET-1 (P=0.036, caspase-3 (P=0.007), respectively] and control group [TNF-α (P=0.008), MDA (P<0.001), MPO (P=0.001), ET-1 (P<0.001), caspase-3 (P<0.001), respectively]. In I-R group, severe damage was detected by hematoxylin-eosin staining. This damage was found less severe in Ada treatment group.

CONCLUSION

The release of cytokines and ET-1 in a large proportion after I-R injury, and generating of ROS in excessive quantity could cause severe damage in the lung tissue. Ada could be considered as a protective agent for lung tissue during I-R process.

Protective Effects of Infliximab on Lung Injury Induced by Methotrexate

INTRODUCTION

Methotrexate (MTX) is used to treat cancers, several forms of arthritis and other rheumatic conditions, although MTX may cause pulmonary toxicity related to the production of free oxygen radicals, various cytokines. Infliximab (IB) with its potent effect on tumor necrosis factor-alpha (TNF-α) inhibition also inhibits the release of endothelin-1 (ET-1). We aimed to investigate whether IB reduces pulmonary damage induced by an overdose of MTX.

METHOD

The rats were divided into 3 groups of 8 animals. The control group was given only saline. One dose of 20mg/kg MTX intraperitoneal was administered in the MTX group. IB 7 mg/kg was given to the MTX+IB (MI) group. Three days after IB was administered, 20mg/kg MTX was given. Five days after MTX was administered, all rats were sacrificed.

RESULTS

The TNF-α, ET-1, malondialdehyde (MDA), myeloperoxidase (MPO) and caspase-3 levels in MTX group were significantly higher than in control groups of TNF-α (P=.001), ET-1 (P=.001), MDA (P=.001), MPO (P=.001) and caspase-3 levels (P=.001) and MI groups of TNF-α (P=.009), ET-1 (P=.001), MDA (P=.047), MPO (P=.007) and caspase-3 levels (P=.003). The MI group had less histopathological damage in lung tissue than the MTX group.

CONCLUSION

Overdose of MTX leads to cytokine release and the formation of reactive oxygen species in addition to increased ET-1 secretion release that causes lung damage. IB, as a potent proinflammatory agent, TNF-α blocker, can decrease ET-1 release and oxidative stress, it may show significant protective effects in lung tissue against damage caused by MTX overdose.

Protective Effects of Infliximab on Lung Injury Induced by Methotrexate

INTRODUCTION

Methotrexate (MTX) is used to treat cancers, several forms of arthritis and other rheumatic conditions, although MTX may cause pulmonary toxicity related to the production of free oxygen radicals, various cytokines. Infliximab (IB) with its potent effect on tumor necrosis factor-alpha (TNF-α) inhibition also inhibits the release of endothelin-1 (ET-1). We aimed to investigate whether IB reduces pulmonary damage induced by an overdose of MTX.

METHOD

The rats were divided into 3 groups of 8 animals. The control group was given only saline. One dose of 20mg/kg MTX intraperitoneal was administered in the MTX group. IB 7 mg/kg was given to the MTX+IB (MI) group. Three days after IB was administered, 20mg/kg MTX was given. Five days after MTX was administered, all rats were sacrificed.

RESULTS

The TNF-α, ET-1, malondialdehyde (MDA), myeloperoxidase (MPO) and caspase-3 levels in MTX group were significantly higher than in control groups of TNF-α (P=.001), ET-1 (P=.001), MDA (P=.001), MPO (P=.001) and caspase-3 levels (P=.001) and MI groups of TNF-α (P=.009), ET-1 (P=.001), MDA (P=.047), MPO (P=.007) and caspase-3 levels (P=.003). The MI group had less histopathological damage in lung tissue than the MTX group.

CONCLUSION

Overdose of MTX leads to cytokine release and the formation of reactive oxygen species in addition to increased ET-1 secretion release that causes lung damage. IB, as a potent proinflammatory agent, TNF-α blocker, can decrease ET-1 release and oxidative stress, it may show significant protective effects in lung tissue against damage caused by MTX overdose.

Activation of ETA Receptor by Endothelin-1 Induces Hepatocellular Carcinoma Cell Migration and Invasion via ERK1/2 and AKT Signaling Pathways

Endothelin-1 (ET-1), a member of endothelins family, binds to ETA receptor (ETAR) and ETB receptor to exert its role in multiple cellular processes. Although ET-1 and its receptors has been reported to be overexpressed in many cancers, and overexpression of ET-1 is able to trigger hepatocarcinogenesis in zebrafish, the functions of ET-1 and its receptors in hepatocellular carcinoma (HCC) cell migration and invasion remain unclear. In the present study, we found that ETAR was greatly expressed in HCC cells and HCC tissues. ETAR expression as well as ET-1 expression was associated with vascular invasion and tumor stage in HCC. Activation of ETAR by ET-1 dose-dependently promoted cell migration and invasion of HCC cells, while silencing of ETAR by siRNA or blocking of ETAR by specific inhibitor resulted in significant reduction in ET-1-mediated migration and invasion. Furthermore, ET-1 induced activation of ERK1/2 and AKT and increased MMP-3 production via ETAR. In addition, using inhibitors of ERK1/2 and AKT, we found that ERK1/2 and AKT pathways were both involved in ETAR-mediated migration, invasion, and MMP-3 production. Taken together, our findings suggest that activation of ETAR by ET-1 promotes HCC cell migration and invasion via activating ERK1/2 and AKT signaling pathways and upregulating MMP-3 expression. Thus, ETAR may play an important role in the progress of HCC.

A Mediterranean diet supplemented with extra virgin olive oil or nuts improves endothelial markers involved in blood pressure control in hypertensive women

PURPOSE

Serum nitric oxide (NO) reduction and increased endothelin-1 (ET-1) play a pivotal role in endothelial dysfunction and hypertension. Considering that traditional Mediterranean diet (TMD) reduces blood pressure (BP), the aim of this study was to analyze whether TMD induced changes on endothelial physiology elements such as NO, ET-1 and ET-1 receptors which are involved in BP control.

METHODS

Non-smoking women with moderate hypertension were submitted for 1 year to interventions promoting adherence to the TMD, one supplemented with extra virgin olive oil (EVOO) and the other with nuts versus a control low-fat diet (30 participants/group). BP, NO, ET-1 and related gene expression as well as oxidative stress biomarkers were measured.

RESULTS

Serum NO and systolic BP (SBP) or diastolic BP (DBP) were negatively associated at baseline, as well as between NO and ET-1. Our findings also showed a DBP reduction with both interventions. A negative correlation was observed between changes in NO metabolites concentration and SBP or DBP after the intervention with TMD + EVOO (p = 0.033 and p = 0.044, respectively). SBP reduction was related to an impairment of serum ET-1 concentrations after the intervention with TMD + nuts (p = 0.008). We also observed changes in eNOS, caveolin 2 and ET-1 receptors gene expression which are related to NO metabolites levels and BP.

CONCLUSIONS

The changes in NO and ET-1 as well as ET-1 receptors gene expression explain, at least partially, the effect of EVOO or nuts on lowering BP among hypertensive women.

Plasma Levels of Acylated Ghrelin in Children with Pulmonary Hypertension Associated with Congenital Heart Disease

This study aims to estimate plasma levels of acylated ghrelin in children with pulmonary hypertension (PH) associated with congenital heart disease (CHD) and to correlate the levels of acylated ghrelin with endothelin-1 (ET-1), nitric oxide (NO), and clinical hemodynamic parameters. We investigated the plasma concentration of acylated ghrelin, ET-1, NO, and the hemodynamic parameters in 20 children with CHD, 20 children with PH-CHD, and 20 normal children. Plasma-acylated ghrelin and NO levels were significantly higher in CHD group than in control subjects (P < 0.001). Moreover, plasma-acylated ghrelin, ET-1, and NO levels were significantly elevated in PH-CHD group compared with the CHD group (P < 0.05). In PH-CHD children, plasma-acylated ghrelin levels correlated positively with pulmonary artery systolic pressure (PASP; r = 0.740, P < 0.001), pulmonary artery diastolic pressure (PADP; r = 0.613, P = 0.004), right ventricular systolic pressure (RVSP; r = 0.642, P = 0.002), mean pulmonary arterial hypertension (mPAP; r = 0.685, P = 0.001), right ventricle diameter (RVD; r = 0.473, P = 0.035), pulmonary artery trunk diameter (PAD; r = 0.613, P = 0.004), NO (r = 0.463, P = 0.04), and ET-1 (r = 0.524, P = 0.018). Plasma-acylated ghrelin levels were elevated both in CHD and in PH-CHD. Increased acylated ghrelin levels correlated positively with ET-1, NO, PASP, PADP, RVSP, mPAP, RVD, and PAD. Acylated ghrelin may be a new biomarker of PH-CHD.