endothelin-1 and Intracranial-Aneurysm

Aneurysmal subarachnoid hemorrhage (SAH) is an acute cerebrovascular emergency resulting from the rupture of a brain aneurysm. Despite only accounting for 5% of all strokes, SAH imposes a significant health burden on society due to its relatively young age at onset. Those who survive the initial bleed are often afflicted with severe disabilities thought to result from delayed cerebral ischemia (DCI). Consequently, elucidating the underlying mechanistic pathways implicated in DCI development following SAH remains a priority. Neuroinflammation has recently been implicated as a promising new theory for the development of SAH complications. However, despite this interest, clinical trials have failed to provide consistent evidence for the use of anti-inflammatory agents in SAH patients. This may be explained by the complexity of SAH as a plethora of inflammatory pathways have been shown to be activated in the disease. By determining how these pathways may overlap and interact, we hope to better understand the developmental processes of SAH complications and how to prevent them. The goal of this review is to provide insight into the available evidence regarding the molecular pathways involved in the development of inflammation following SAH and how SAH complications may arise as a result of these inflammatory pathways.

Topics: Brain Ischemia; Endothelin-1; Humans; Inflammation; Intracranial Aneurysm; Metabolic Networks and Pathways; Mitogen-Activated Protein Kinases; Oxyhemoglobins; Platelet Activating Factor; Reactive Oxygen Species; Serotonin; Subarachnoid Hemorrhage; Thrombin

Cerebral vasospasm lingers as the leading preventable cause of death and disability in patients who experience aneurysmal subarachnoid hemorrhage. Despite the potentially devastating consequences of cerebral vasospasm, the mechanisms behind it are incompletely understood. Nitric oxide, endothelin-1, bilirubin oxidation products and inflammation appear to figure prominently in its pathogenesis. Therapies directed at many of these mechanisms are currently under investigation and hold significant promise for an ultimate solution to this substantial problem.

Topics: Anti-Inflammatory Agents; Bilirubin; Calcium Channel Blockers; Cerebral Angiography; Encephalitis; Endothelin-1; Fibrinolytic Agents; Heme Oxygenase (Decyclizing); Humans; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Intracranial Aneurysm; Magnesium; Muscle Contraction; Muscle, Smooth, Vascular; Nitric Oxide; Subarachnoid Hemorrhage; Time Factors; Vasospasm, Intracranial

Molecular biologic investigations in the past decades have begun to unravel the intracellular mechanisms involved in vasomotor regulation of cerebral blood vessels and their failure in delayed cerebral vasospasm produced by aneurysmal subarachnoid hemorrhage. Progress in deciphering macrovascular regulatory mechanisms and their failure in delayed cerebral vasospasm induced by aneurysmal subarachnoid hemorrhage have revealed that there are at least two important vasoactive substances-nitric oxide and endothelin-1-that play important roles in the clinical manifestations of subarachnoid-hemorrhage-induced cerebral vasospasm. Nitric oxide is a cell-membrane-permeable free radical gas that accounts for the phenomenon of vasodilatation by a variety of vasodilator agents. Endothelin-1, a 21 amino acid peptide, is one of the most potent constricting factors. Cerebral vasospasm is thought to represent a disturbance in the cerebral vasomotor equilibrium for which these two physiologically antagonistic compounds are at least partly responsible. Advances in our understanding of the molecular responses of the cerebral vasculature to subarachnoid hemorrhage should lead to more comprehensive management as knowledge becomes translated into development of effective pharmacologic agents to reverse or prevent cerebral vasospasm following aneurysmal subarachnoid hemorrhage.

Topics: Endothelin-1; Humans; Intracranial Aneurysm; Nitric Oxide; Subarachnoid Hemorrhage; Time Factors; Vasospasm, Intracranial

This study aimed to study the association between rs12976445 polymorphism and the incidence of IA re-bleeding. Genotype and allele frequency analysis was performed to study the association between rs12976445 polymorphism and the risk of IA re-bleeding. Western blot, ELISA and real-time RT-PCR were conducted to measure the relative expression of miR-125a, ET1 mRNA and ET1 protein. Computational analysis and luciferase assays were utilized to investigate the association between the expression of miR-125a and ET1 mRNA. No significant differences were observed between IA patients with or without symptoms of re-bleeding. Subsequent analyses indicated that the T allele was significantly associated with the reduced risk of IA re-bleeding. In patients carrying the CC genotype, miR-125a level was up-regulated while ET1 mRNA/protein levels were reduced compared with those in patients carrying the CT or TT genotype. And ET1 mRNA was identified as a virtual target gene of miR-125a with a potential miR-125a binding site located on its 3'UTR. Accordingly, the ET mRNA/protein levels could be suppressed by the transfection of miR-125a precursors, but the transfection of ET1 siRNA exhibited no effect on the expression of miR-125a. Therefore, an increased level of miR-125a can lead to the increased risk of IA re-bleeding. Since miR-125a level is higher in CC-genotyped patients, it can be concluded that the presence of T allele in the rs12976445 polymorphism is associated with a lower risk of IA re-bleeding, and miR-125a may be used as a novel diagnostic and therapeutic target for IA rupture.

Topics: 3' Untranslated Regions; Antifibrinolytic Agents; Brain; Cell Line; Cerebral Arteries; Endothelin-1; Female; Gene Frequency; Genetic Association Studies; Genetic Predisposition to Disease; Humans; Intracranial Aneurysm; Male; MicroRNAs; Polymorphism, Single Nucleotide; Risk; Subarachnoid Hemorrhage

OBJECTIVE Endothelin-1, a potent vasoconstrictor, and its receptors may be involved in the pathogenesis of aneurysmal subarachnoid hemorrhage (aSAH), clinical vasospasm, delayed cerebral ischemia (DCI), and functional outcome following aSAH. In the present study, common endothelin single nucleotide polymorphisms (SNPs) and their relation to aSAH were evaluated. METHODS Blood samples from all patients enrolled in the Cerebral Aneurysm Renin Angiotensin System (CARAS) study were used for genetic evaluation. The CARAS study prospectively enrolled patients with aSAH at 2 academic institutions in the US from 2012 to 2015. Common endothelin SNPs were detected using 5' exonnuclease (TaqMan) genotyping assays. Analysis of associations between endothelin SNPs and aSAH and its clinical sequelae was performed. RESULTS Samples from 149 patients with aSAH and 50 controls were available for analysis. In multivariate logistic regression analysis, the TG (odds ratio [OR] 2.102, 95% confidence interval [CI] 1.048-4.218, p = 0.036) and TT genotypes (OR 7.884, 95% CI 1.003-61.995, p = 0.05) of the endothelin-1 T/G SNP (rs1800541) were significantly associated with aSAH. There was a dominant effect of the G allele (CG/GG genotypes; OR 4.617, 95% CI 1.311-16.262, p = 0.017) of the endothelin receptor A G/C SNP (rs5335) on clinical vasospasm. Endothelin SNPs were not associated with DCI or functional outcome. CONCLUSIONS Common endothelin SNPs were found to be associated with presentation with aSAH and clinical vasospasm. Further studies are required to elucidate the relevant pathophysiology and its potential implications in the treatment of patients with aSAH.

Topics: Brain Ischemia; Endothelin-1; Female; Follow-Up Studies; Genetic Association Studies; Genetic Predisposition to Disease; Humans; Intracranial Aneurysm; Male; Middle Aged; Polymorphism, Single Nucleotide; Prospective Studies; Receptor, Endothelin A; Receptor, Endothelin B; Subarachnoid Hemorrhage; Treatment Outcome; Vasospasm, Intracranial

Aneurysmal subarachnoid hemorrhage is a type of stroke with high morbidity and mortality. Increased endothelin-1 (ET-1) levels have been associated with increased risk of cerebral vasospasm, which is associated with increased morbidity. The purpose of this study was to investigate the relationships between ET-1 genotypes and ET-1 protein levels in cerebrospinal fluid (CSF) measured 72 hr before angiographic vasospasm measurement in subjects at high risk of cerebral vasospasm. Specifically, this study evaluated the differences between variant positive and variant negative groups of nine different ET-1 single-nucleotide polymorphisms (SNPs) in relationship with the ET-1 protein exposure rate. The CSF ET-1 protein levels were quantified using enzyme-linked immunosorbent assay. One functional SNP and eight ET-1 tagging SNPs were selected because they represent genetic variability in the entire ET-1 gene. The variant negative group of SNP rs2070699 was associated with a significantly higher ET-1 exposure rate than the variant positive group (p = 0.004), while the variant positive group of the rs5370 group showed a trend toward association with a higher ET-1 exposure rate (p = 0.051). Other SNPs were not informative. This is the first study to show differences in ET-1 exposure rate 72 hr before angiography in relation to ET-1 genotypes. These exploratory findings need to be replicated in a larger study; if replicated, these differences in genotypes may be a way to inform clinicians of those patients at a higher risk of increased ET-1 protein levels, which may lead to a higher risk of angiographic vasospasm.

Topics: Endothelin-1; Female; Genotyping Techniques; Humans; Intracranial Aneurysm; Male; Middle Aged; Polymorphism, Single Nucleotide; Radiography; Subarachnoid Hemorrhage; Vasospasm, Intracranial

Increased endothelin-1 (ET-1) production and diminished nitric oxide synthase (NOS) bioavailability has been observed in aneurysmal subarachnoid hemorrhage (SAH). The authors previously found that 6-mercaptopurine (6-mp) is effective in preventing and reversing arterial narrowing in a rodent SAH model. This present study is of interest to examine the effect of 6-mp on ET-1/endothelial nitric oxide synthase (eNOS) in this animal model.. A rodent double hemorrhage SAH model was employed. Animals were randomly assigned to six groups (sham, SAH only, vehicle, 0.5, 1.0 and 2 mg kg(-1) day(-1) 6-mp treatment). Monoclonal CD45 immunostaining was utilized to evaluate monocytes and microglia. The level of pro-inflammatory cytokines, such as IL-1, IL-6 and TNF-α(RT-PCR), and ET-1 (ELISA) was measured. The basilar arteries (BAs) were harvested and sliced, and their cross-sectional areas were determined. Radiolabeled NOS assay kit was applied to detect eNOS.. Morphologically, convolution of internal elastic lamina, endothelial cells distortion, and necrotic smooth muscle were prevalently present in the basilar artery of SAH groups, which was absent in the 1 and 2 mg kg(-1) day(-1) 6-mp plus SAH group or the healthy controls. Significant vasospasm was noted in the vehicle group (lumen patency, 54.6%, p ≤ 0.01 compared with the sham group), but it was less prominent in the 2 mg kg(-1) day(-1) 6-mp treatment group (lumen patency, 87.6%, p < 0.05). In addition, administration with 2 mg kg(-1) day(-1) 6-mp reduced cytokine levels by 11%, 47%, and 34% for IL-1, IL-6, and TNF-α, respectively, and increased ET-1 levels were found in all the animals subject to SAH (SAH only, SAH plus vehicle, SAH plus 0.5 and 1.0 mg kg(-1) day(-1) 6-mp) except in the 2 mg kg(-1) day(-1) 6-mp SAH group, when compared with the healthy controls (no SAH). Meanwhile, treatment with 6-mp did not induce the levels of expressed eNOS in BAs in the 6-mp groups (0.5, 1.0, and 2 mg kg(-1) day(-1) 6-mp plus SAH) when compared with that in the SAH groups (p > 0.1).. In summary, treatment with 6-mp decreased the release of pro-inflammatory cytokines and diminished experimental vasospasm. This study offered first evidence that 6-mp dose-dependently reduces the level of ET-1 in a NO-independent mechanism, which corresponds to its antivasospastic effect in the condition of chronic vasospasm.

Topics: Aneurysm, Ruptured; Animals; Chemotaxis; Connective Tissue; Cytokines; Disease Models, Animal; Dose-Response Relationship, Drug; Endothelin-1; Immunosuppressive Agents; Inflammation Mediators; Intracranial Aneurysm; Male; Mercaptopurine; Microglia; Muscle, Smooth, Vascular; Nitric Oxide; Nitric Oxide Synthase; Rats; Rats, Sprague-Dawley; Subarachnoid Hemorrhage; Vasospasm, Intracranial

Though cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH) has been recognized for over half a century, it remains a major complication in patients with SAH. Clinical studies have shown that elevated levels of endothelin-1 (ET-1) are present in the cerebrospinal fluid of patients with SAH, suggesting that ET-1-mediated vasoconstriction contributes to vascular constriction after SAH. Administration of estrogen promotes vasodilation in humans and in experimental animals, in part by decreasing the production of ET-1. This study evaluated the influence of 17beta-estradiol (E2) on the production of ET-1 and cerebrovasospasm in an experimental SAH 2-hemorrhage model in rat. A 30-mm Silastic tube filled with E2 in corn oil (0.3 mg/ml) was subcutaneously implanted in male rats just before SAH induction. The degree of vasospasm was determined by averaging the cross-sectional areas of basilar artery 7 days after first SAH. Plasma samples collected before death were assayed for ET-1. The protective effect of E2 in attenuating vasospasm achieved statistical significance when compared with the SAH only or SAH plus vehicle groups (P < 0.01). Concentrations of ET-1 were higher in the SAH only and SAH plus vehicle groups than in controls (P < 0.001). Serum levels of ET-1 in the SAH plus E2 and E2 only groups were significantly lower than those in the SAH only and SAH plus vehicle groups (P < 0.001). There was no significant difference between ET-1 levels in the healthy control and SAH plus E2 groups. A significant correlation was found between the cross-sectional areas of basilar artery and ET-1 levels (P < 0.001). The beneficial effect of E2 in attenuating SAH-induced vasospasm may be due in part to decreasing ET-1 production after SAH. The role of E2 in the treatment of cerebral vasospasm after SAH is promising and is worthy of further investigation.

Topics: Animals; Disease Models, Animal; Endothelin-1; Estradiol; Intracranial Aneurysm; Male; Random Allocation; Rats; Rats, Sprague-Dawley; Subarachnoid Hemorrhage; Vasospasm, Intracranial

Cerebral aneurysms and arteriovenous malformations (AVM) are a common cause of stroke and cerebral hemorrage. Both are often discovered when they rupture, causing subarachnoid hemorrhage (SAH). SAH-induced vasospasm is mediated by enhanced vasoconstriction due to endothelin-1 (ET-1). We investigated whether endothelial cells (ECs) obtained from aneurysm and AVM express phenotypic and genotypic alterations contributing to the development of vasospasm after SAH. We isolated ECs from human AVM and aneurysm and then confirmed their EC origin by polymerase chain reaction and immunocytochemistry with endothelial markers. Experiments were also carried out with human cerebral microvascular and umbilical vein ECs (HCECs and HUVECs respectively) for comparison. We tested EC proliferation ability and microtubule formation in Matrigel at different cell passages. Five aneurysm (3 ruptured, 2 unruptured) and 3 AVM (2 ruptured, 1 unruptured) ECs were tested for ET-1 release in the culture medium. Aneurysm and AVM ECs expressed von Willebrand factor, Adrenomedullin, and exhibited a progressive reduction of proliferation and in vitro angiogenic ability after the V passage. Significantly higher levels of ET-1 have been detected in ECs from ruptured aneurysms and AVMs. We report the first successful isolation and characterization of primary EC lines from human cerebral vascular lesions. Augmented release of ET-1 is correlated with the rupture of the abnormal vessel confirming its role in vasospasm after SAH. Furthermore, ECs obtained from these vascular malformations can be used as an experimental model to study SAH-induced vasoconstriction.

Topics: Adrenomedullin; Cell Line; Constriction, Pathologic; Endothelial Cells; Endothelin-1; Endothelium, Vascular; Humans; Intracranial Aneurysm; Intracranial Arteriovenous Malformations; Protein Transport; RNA, Messenger; Rupture, Spontaneous; Subarachnoid Hemorrhage; von Willebrand Factor

Whereas the removal of subarachnoid blood is possible during early-stage aneurysm surgery, this cannot be achieved in aneurysms treated by endovascular means. The levels of potential spasmogens in the cerebrospinal fluid (CSF) in patients receiving endovascular treatment might therefore be higher, with the potential for more severe post-subarachnoid hemorrhage (SAH) vasospasm.. Serum and CSF concentrations of big endothelin (ET)-1 were serially measured in patients with SAH receiving one of the following treatments: 1) early (within 72 hours of SAH) aneurysm surgical treatment (15 patients), 2) early endovascular treatment (17 patients), or 3) no intervention in the acute phase (12 patients). In patients suffering delayed infarctions higher levels of big ET-1 CSF were demonstrated than in those without infarctions (p = 0.01). In patients in whom surgery was performed in the acute phase lower big ET-1 CSF concentrations were demonstrated than in those who received embolization treatment or no treatment (p = 0.02). Subgroup analysis demonstrated that in patients receiving early endovascular treatment, higher big ET-1 CSF concentrations were revealed than in those undergoing early aneurysm surgery; this was true for patients with (microsurgerytreated, 1.84 +/- 0.83 pg/ml; and embolization-treated 2.19 +/- 0.54 pg/ml) and without (microsurgery-treated 1.76 +/- 0.61 pg/ml; and embolization-treated 2.01 +/- 0.48 pg/ml) delayed infarctions.. Among patients with SAH who received treatment during the acute phase, those undergoing early aneurysm surgery were shown to have lower big ET-1 CSF levels than those receiving embolization and no treatment (that is, the nonsurgical treatment groups). The clinical significance of this finding remains to be established in future clinical trials, because in the present study the trend toward lower levels of big ET-1 CSF in the microsurgically treated group was not paralleled by a lower delayed stroke rate or an improvement in neurological outcome.

Topics: Adult; Aged; Aged, 80 and over; Aneurysm, Ruptured; Endothelin-1; Enzyme-Linked Immunosorbent Assay; Female; Humans; Intracranial Aneurysm; Male; Middle Aged; Time Factors