Pharmacological Inhibition of Epidermal Growth Factor Receptor Prevents Intracranial Aneurysm Rupture by Reducing Endoplasmic Reticulum Stress.

BACKGROUND: Multiple pathways and factors are involved in the rupture of intracranial aneurysms. The EGFR (epidermal growth factor receptor) has been shown to mediate inflammatory vascular diseases, including atherosclerosis and aortic aneurysm. However, the role of EGFR in mediating intracranial aneurysm rupture and its underlying mechanisms have yet to be determined. Emerging evidence indicates that endoplasmic reticulum (ER) stress might be the link between EGFR activation and the resultant inflammation. ER stress is strongly implicated in inflammation and apoptosis of vascular smooth muscle cells, both of which are key components of the pathophysiology of aneurysm rupture. Therefore, we hypothesized that EGFR activation promotes aneurysmal rupture by inducing ER stress. METHODS: Using a preclinical mouse model of intracranial aneurysm, we examined the potential roles of EGFR and ER stress in developing aneurysmal rupture. RESULTS: Pharmacological inhibition of EGFR markedly decreased the rupture rate of intracranial aneurysms without altering the formation rate. EGFR inhibition also significantly reduced the mRNA (messenger RNA) expression levels of ER-stress markers and inflammatory cytokines in cerebral arteries. Similarly, ER-stress inhibition also significantly decreased the rupture rate. In contrast, ER-stress induction nullified the protective effect of EGFR inhibition on aneurysm rupture. CONCLUSIONS: Our data suggest that EGFR activation is an upstream event that contributes to aneurysm rupture via the induction of ER stress. Pharmacological inhibition of EGFR or downstream ER stress may be a promising therapeutic strategy for preventing aneurysm rupture and subarachnoid hemorrhage.

Does the use of oral contraceptives or hormone replacement therapy offer protection against the formation or rupture of intracranial aneurysms in women?: a systematic review and meta-analysis.

OBJECTIVE: The aim of this study was to carry out a systematic review of the literature with meta-analysis to evaluate the effect of using oral contraceptive and hormone replacement therapy as a protective factor in the formation of intracranial aneurysms and subarachnoid hemorrhage. METHODS: This is a systematic review of the literature with meta-analysis, using PubMed and Embase as databases and the PRISMA method. Case-control and cohort studies published until December 2022 were included in this review. RESULTS: Four studies were included in this review; three of which were eligible for meta-analysis. Regarding the use of oral contraceptive and the development of subarachnoid hemorrhage, there was a lower risk of aneurysm rupture with an odds ratio 0.65 (confidence interval 0.5-0.85). In the analysis of patients using hormone replacement therapy and developing subarachnoid hemorrhage, there was also a lower risk of aneurysm rupture with an OR 0.54 (CI 0.39-0.74). Only one article analyzed the formation of intracranial aneurysm and the use of hormone replacement therapy and oral contraceptive, and there was a protective effect with the use of these medications. oral contraceptive: OR 2.1 (CI 1.2-3.8) and hormone replacement therapy: OR 3.1 (CI 1.5-6.2). CONCLUSION: The use of hormone replacement therapy and oral contraceptive has a protective effect in intracranial aneurysm rupture and formation.

Wheat ergot fungus-derived and modified drug for inhibition of intracranial aneurysm rupture due to dysfunction of TLR-4 receptor in Alzheimer's disease.

BACKGROUND: Alzheimer's disease (AD) is a form of dementia that strikes elderly people more frequently than it does younger people. The cognitive skills and memory of Alzheimer's sufferers continue to deteriorate over time. Recent studies have shown that patients with AD have greater amounts of inflammatory markers in their bodies, which suggests that inflammation occurs early on in the progression of the disease. There is a possibility that Aß oligomers and fibrils can be recognised by TLRs, in addition to the microglial receptors CD14, CD36, and CD47. When Aß binds to either CD36 or TLR4, it sets off a chain reaction of inflammatory chemokines and cytokines that ultimately results in neurodegeneration. Diabetes and Alzheimer's disease have both been recently related to TLR4. The activation of TLR4 has been connected to a variety of clinical difficulties that are associated with diabetes, in addition to the internal environment of the body and the microenvironment of the brain. TLR4 inhibitors have been shown in clinical investigations to not only lessen the likelihood of getting sick but also to increase the average longevity. RESULT: In this work we used molecular docking and molecular dynamics modelling to investigate the effectiveness of FDA-approved antidiabetic plant derived drugs in combating the TLR4 receptor. Molecular docking experiments were used to make a prediction regarding the most important interactions involving 2-Bromoergocryptine Mesylate. With a binding affinity of -8.26 kcal/mol, it stood out from the other candidates as the one with the greatest potential. To verify the interaction pattern that takes place between 2-Bromoergocryptine Mesylate and the TLR4 receptor, a molecular dynamic simulation was run at a time scale of 150 nanoseconds. Because of this, 2-Bromoergocryptine Mesylate was able to make substantial contact with the active site, which led to increased structural stability during the process of the complex's dynamic development. CONCLUSION: As a result of this, the results of our research may be relevant for future research into the efficacy of 2-bromoergocryptine mesylate as a potential lead treatment for TLR4 receptors in intracranial aneurysm rupture in AD.

Risk factor management matters more than pharmaceutical cyclooxygenase-2 inhibition in the prevention of de novo intracranial aneurysms.

BACKGROUND AND PURPOSE: Pathophysiological studies of saccular intracranial aneurysm (sIA) disease have shown that inflammation plays a crucial role in sIA development. Pharmaceutical inhibition of COX-2-PGE2-NF-κB signaling (COX-2, cyclooxygenase-2; PGE2, prostaglandin E2; NF-κB, nuclear factor κB) has been shown in animal models to inhibit sIA formation and progression suggesting that use of medication inhibiting COX-2 could reduce intracranial aneurysm formation also in patients. METHODS: The impact of COX-2 inhibition on de novo sIA formation was studied in two cohorts: in a previously described angiographically followed cohort of 1419 sIA patients and in a cohort of 117 sIA patients treated with stenting or stent-assisted embolization. Patients were identified from our population-based Kuopio Intracranial Aneurysm Database. Data on the use of anti-inflammatory medications and hospital diagnoses were obtained from national registries. Risk factors were identified by univariate and multivariate analyses. RESULTS: De novo sIA patients were younger and more often smokers. Use of COX-2 selective inhibitors or nonsteroidal anti-inflammatory drugs did not significantly reduce de novo sIA formation, but the percentage of patients with de novo sIA formation was smaller in patients with prescribed regular acetylsalicylic acid medication (1.1% vs. 3.6%). In the multivariate analysis, however, neither acetylsalicylic acid use nor other type of pharmaceutical inhibition of COX-2 reduced the formation of de novo sIAs. The risk was mostly affected by age, smoking history and irregular usage of antihypertensive medication regardless of used COX-2 inhibition level. CONCLUSION: For the prevention of de novo sIA formation, risk factor management with focus on cessation of smoking and treating hypertension adequately seems more important than pharmaceutical COX-2 inhibition.

Pharmacological inhibition of epidermal growth factor receptor attenuates intracranial aneurysm formation by modulating the phenotype of vascular smooth muscle cells.

AIM: To study the effect of pharmacological inhibition of epidermal growth factor receptor (EGFR) on intracranial aneurysm (IA) initiation. METHODS: Human IA samples were analyzed for the expression of p-EGFR and alpha smooth muscle actin (α-SMA) by immunofluorescence (IF). Rat models of IA were established to evaluate the ability of the EGFR inhibitor, erlotinib, to attenuate the incidence of IA. We analyzed anterior cerebral artery tissues by pathological and proteomic detection for the expression of p-EGFR and relevant proteins, and vessel casting was used to evaluate the incidence of aneurysms in each group. Rat vascular smooth muscle cells (VSMCs) and endothelial cells were extracted and used to establish an in vitro co-culture model in a flow chamber with or without erlotinib treatment. We determined p-EGFR and relevant protein expression in VSMCs by immunoblotting analysis. RESULTS: Epidermal growth factor receptor activation was found in human IA vessel walls and rat anterior cerebral artery walls. Treatment with erlotinib markedly attenuated the incidence of IA by inhibiting vascular remodeling and pro-inflammatory transformation of VSMC in rat IA vessel walls. Activation of EGFR in rat VSMCs and phenotypic modulation of rat VSMCs were correlated with the strength of shear stress in vitro, and treatment with erlotinib reduced phenotypic modulation of rat VSMCs. In vitro experiments also revealed that EGFR activation could be induced by TNF-α in human brain VSMCs. CONCLUSIONS: These results suggest that EGFR plays a critical role in the initiation of IA and that the EGFR inhibitor erlotinib protects rats from IA initiation by regulating phenotypic modulation of VSMCs.

Aspirin treatment prevents inflammation in experimental bifurcation aneurysms in New Zealand White rabbits.

BACKGROUND: Aneurysm wall degeneration is linked to growth and rupture. To address the effect of aspirin (ASA) on aneurysm formation under various wall conditions, this issue was analyzed in a novel rabbit bifurcation model. METHODS: Bifurcation aneurysms created in 45 New Zealand White rabbits were randomized to vital (n=15), decellularized (n=13), or elastase-degraded (n=17) wall groups; each group was assigned to a study arm with or without ASA. At follow-up 28 days later, aneurysms were evaluated for patency, growth, and wall inflammation at macroscopic and histological levels. RESULTS: 36 rabbits survived to follow-up at the end of the trial. None of the aneurysms had ruptured. Patency was visualized in all aneurysms by intraoperative fluorescence angiography and confirmed in 33 (92%) of 36 aneurysms by MRI/MRA. Aneurysm size was significantly increased in the vital (without ASA) and elastase-degraded (with and without ASA) groups. Aneurysm thrombosis was considered complete in three (50%) of six decellularized aneurysms without ASA by MRI/MRA. Locoregional inflammation of the aneurysm complex was significantly reduced in histological analysis among all groups treated with ASA. CONCLUSION: ASA intake prevented inflammation of both the periadventitial tissue and aneurysm wall, irrespective of initial wall condition. Although ASA prevented significant growth in aneurysms with vital walls, this preventive effect did not have an important role in elastase-degraded pouches. In possible translation to the clinical situation, ASA might exert a potential preventive effect during early phases of aneurysm formation in patients with healthy vessels but not in those with highly degenerative aneurysm walls.

Could outcomes of intracranial aneurysms be better predict using serum creatinine and glomerular filtration rate?

Purpose: To analyze the role of serum creatinine levels as a biomarker of intracranial aneurysm outcomes. Methods: This is a prospective analysis of outcomes of patients with intracranial aneurysm. One hundred forty-seven patients with serum creatinine at admission and 6 months follow up were included. Linear and logistic regressions were used to analyze the data. Modified Rankin scale (mRS) was used to assess outcome. Results: Creatinine level was not directly related to aneurysm outcome nor aneurysm rupture (p > 0.05). However, patients with a glomerular filtration rate (GFR) lower than 72.50 mL·min­1 had an odds ratio (OR) of 3.049 (p = 0.006) for worse outcome. Similarly, aneurysm rupture had an OR of 2.957 (p = 0.014) for worse outcomes. Stepwise selection model selected 4 variables for outcomes prediction: serum creatinine, sex, hypertension and treatment. Hypertensive patients had, on average, an increase in 0.588 in mRS (p = 0.022), while treatment with microsurgery had a decrease in 0.555 (p = 0.038). Conclusions: Patients with higher GFR had better outcomes after 6 months. Patients with higher GFR had better outcomes after 6 months. Creatinine presented an indirect role in GFR values and should be included in models for outcome prediction.

Aspirin and growth, rupture of unruptured intracranial aneurysms: A systematic review and meta-analysis.

OBJECTIVES: Aspirin has been suggested as a potential therapeutic strategy to prevent the growth and rupture of unruptured intracranial aneurysms (UIAs), but there is still controversy. The aim of this systematic review and meta-analysis is to determine the association between aspirin use and growth, rupture of UIAs. METHODS: We performed a systematic literature search of electronic databases to identify cohort and case-control studies investigating the relationship between aspirin use and growth or rupture of UIAs. Pooled odds ratio (OR) with corresponding 95% confidence interval (CI) were calculated using a random effects model. Heterogeneity among studies was quantified using the I2 statistic, and potential publication bias was assessed using funnel plots. Sensitivity analysis was performed to verify the robustness of the intention-to-treat results. Subgroup analysis was conducted according to the frequency of aspirin use. RESULTS: We identified 8 studies comprising 10,518 participants. The risk of bias was low to moderate. The pooled estimate showed that aspirin use was associated with a lower likelihood of growth of UIAs (OR = 0.25, 95% CI = 0.11-0.55; p = 0.0005) without statistical heterogeneity (p for Cochran Q statistic = 0.62, I2 = 0%). Likewise, aspirin intake also significant decreased 58% risk of intracranial aneurysms rupture (OR = 0.42, 95% CI = 0.29-0.60; p < 0.00001) with moderate heterogeneity (p for Cochran Q statistic = 0.005, I2 = 66%). Similar results were observed in the sensitivity analysis. Pooled OR of aspirin frequency subgroup analysis for less than or equal to 2 times per week was 0.82 (95%CI = 0.40-1.72; I2 = 0%), for at least 3 times per week to daily was 0.25 (95%CI = 0.12-053; I2 = 0%), for daily was 0.59 (95%CI: 0.47-0.74; I2 = 0%), and for unknown was 0.26 (95%CI: 0.15-0.45; I2 = 51%). CONCLUSIONS: The results of this systematic review and meta-analysis indicates a beneficial effect of aspirin on growth and rupture of UIAs.

Simvastatin increases circulating endothelial progenitor cells and inhibits the formation of intracranial aneurysms in rats with diet-induced hyperhomocysteinemia.

BACKGROUND AND PURPOSE: Endothelial dysfunction triggers early pathological changes in artery, leading to the formation of intracranial aneurysm (ICA). Increase in plasma homocysteine (Hcy) impairs endothelium and endothelial progenitor cells (EPCs) are critical in repairing damaged endothelium. The aim of this study was to assess the impact of simvastatin on ICA formation in rats with hyperhomocysteinemia (HHcy). METHODS: ICAs were induced in Male Sprague-Dawley rats after surgical induction in the presence of HHcy induced by a high L-methionine diet with or without oral simvastatin treatment. The size and media thickness of ICAs were evaluated 2 months after aneurysm induction. EPCs and serum vascular endothelial grow factor (VEGF) were measured be flow cytometry and ELISA respectively. Plasma Hcy levels and expression of VEGF, endothelial nitric oxide synthase (eNOS), inducible nitric oxide synthase (iNOS), matrix metalloproteinase-2 (MMP-2), and MMP-9 in aneurysmal walls were examined and correlated with ICA formation. RESULTS: HHcy accelerates ICA formation and rats treated with simvastatin exhibited a significant increase in media thickness and a reduction in aneurysmal size. Simvastatin increased levels of circulating EPCs and decreased iNOS, MMP-2, MMP-9 and VEGF mRNA levels, while increased eNOS mRNA in aneurysmal tissue. CONCLUSION: In a rat model, HHcy reduces circulating EPCs and accelerates ICA formation. Simvastatin treatment increases circulating EPCs and inhabits the formation of ICA. We have shown a close association among circulating EPCs, biochemical markers related to vascular remodeling and the formation of ICA.

Roles of Phytoestrogen in the Pathophysiology of Intracranial Aneurysm.

Background and Purpose: The incidences of intracranial aneurysm and aneurysmal subarachnoid hemorrhage are high in postmenopausal women. Although population-based studies suggest that hormone replacement therapy is beneficial for postmenopausal women with intracranial aneurysms, estrogen replacement may no longer be recommended for the prevention of chronic diseases given its association with adverse outcomes, such as cancer and ischemic stroke. The isoflavone daidzein and its intestinal metabolite equol are bioactive phytoestrogens and potent agonists of estrogen receptors. Given their estrogenic properties, we investigated whether the isoflavones daidzein and equol are protective against the formation and rupture of intracranial aneurysms in a mouse model of the postmenopausal state. Methods: We induced intracranial aneurysms in ovariectomized adult female mice using a combination of induced systemic hypertension and a single injection of elastase into the cerebrospinal fluid. We fed the mice with an isoflavone-free diet with/without daidzein supplementation, or in a combination of intraperitoneal equol, or oral vancomycin treatment. We also used estrogen receptor beta knockout mice. Results: Both dietary daidzein and supplementation with its metabolite, equol, were protective against aneurysm formation in ovariectomized mice. The protective effects of daidzein and equol required estrogen receptor-ß. The disruption of the intestinal microbial conversion of daidzein to equol abolished daidzein's protective effect against aneurysm formation. Mice treated with equol had lower inflammatory cytokines in the cerebral arteries, suggesting that phytoestrogens modulate inflammatory processes important to intracranial aneurysm pathogenesis. Conclusions: Our study establishes that both dietary daidzein and its metabolite, equol, protect against aneurysm formation in ovariectomized female mice through the activation of estrogen receptor-ß and subsequent suppression of inflammation. Dietary daidzein's protective effect required the intestinal conversion to equol. Our results indicate the potential therapeutic value of dietary daidzein and its metabolite, equol, for the prevention of the formation of intracranial aneurysms and related subarachnoid hemorrhage.

Candidate drugs for preventive treatment of unruptured intracranial aneurysms: A cross-sectional study.

BACKGROUND AND PURPOSE: Establishment of drug therapy to prevent rupture of unruptured intracranial aneurysms (IAs) is needed. Previous human and animal studies have gradually clarified candidate drugs for preventive treatment of IA rupture. However, because most of these candidates belong to classes of drugs frequently co-administered to prevent cardiovascular diseases, epidemiological studies evaluating these drugs simultaneously should be performed. Furthermore, because drugs included in the same class may have different effects in terms of disease prevention, drug-by-drug assessments are important for planning intervention trials. MATERIALS AND METHODS: We performed a cross-sectional study enrolling patients diagnosed with IAs between July 2011 and June 2019 at our institution. Patients were divided into ruptured or unruptured groups. The drugs investigated were selected according to evidence suggested by either human or animal studies. Univariate and multivariate logistic regression analyses were performed to assess the association of drug treatment with rupture status. We also performed drug-by-drug assessments of the association, including dose-response relationships, with rupture status. RESULTS: In total, 310 patients with ruptured and 887 patients with unruptured IAs were included. Multivariate analysis revealed an inverse association of statins (odds ratio (OR), 0.54; 95% confidence interval (CI) 0.38-0.77), calcium channel blockers (OR, 0.41; 95% CI 0.30-0.58), and angiotensin II receptor blockers (ARBs) (OR, 0.67; 95% CI 0.48-0.93) with ruptured IAs. Moreover, inverse dose-response relationships with rupture status were observed for pitavastatin and rosuvastatin among statins, benidipine, cilnidipine, and amlodipine among calcium channel blockers, and valsartan, azilsartan, candesartan, and olmesartan among ARBs. Only non-aspirin non-steroidal anti-inflammatory drugs were positively associated with ruptured IAs (OR, 3.24; 95% CI 1.71-6.13). CONCLUSIONS: The present analysis suggests that several types of statins, calcium channel blockers, and ARBs are candidate drugs for preventive treatment of unruptured IAs.

Aspirin and Growth of Small Unruptured Intracranial Aneurysm: Results of a Prospective Cohort Study.

BACKGROUND AND PURPOSE: The role of aspirin in unruptured intracranial aneurysm (UIA) growth remains largely unknown. We aim to identify whether aspirin is associated with a lower rate of UIA growth in patients with UIA <7 mm. METHODS: This prospective cohort study consecutively enrolled patients with UIAs <7 mm with ischemic cerebrovascular disease between January 2016 and December 2019. Baseline and follow-up patient information, including the use of aspirin and blood pressure level, were recorded. Patients were considered aspirin users if they took aspirin, including standard- and low-dose aspirin, ≥3× per week. The primary end point was aneurysm growth in any direction or an indisputable change in aneurysm shape. RESULTS: Among the 315 enrolled patients, 272 patients (86.3%) underwent imaging examinations during follow-up (mean follow-up time, 19.6±12.7 months). A total of 113 patients were continuously treated with aspirin. UIA growth occurred in 31 (11.4%) patients. In the multivariate Cox analysis, specific aneurysm locations (anterior communicating artery, posterior communicating artery, or middle cerebral artery; hazard ratio, 2.89 [95% CI, 1.22-6.88]; P=0.016) and a UIA size of 5 to <7 mm (hazard ratio, 7.61 [95% CI, 3.02-19.22]; P<0.001) were associated with a high risk of UIA growth, whereas aspirin and well-controlled blood pressure were associated with a low risk of UIA growth (hazard ratio, 0.29 [95% CI, 0.11-0.77]; P=0.013 and hazard ratio, 0.25 [95% CI, 0.10-0.66]; P=0.005, respectively). The cumulative annual growth rates were as high as 40.0 and 53.3 per 100 person-years in the high-risk patients (>1 risk factor) with and without aspirin, respectively. CONCLUSIONS: Aspirin therapy and well-controlled blood pressure are associated with a low risk of UIA growth; the incidence of UIA growth in high-risk patients in the first year is high, warranting intensive surveillance in this patient group. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02846259.

Role of pregnancy and female sex steroids on aneurysm formation, growth, and rupture: a systematic review of the literature.

OBJECTIVE: Women have been shown to have a higher risk of cerebral aneurysm formation, growth, and rupture than men. The authors present a review of the recently published neurosurgical literature that studies the role of pregnancy and female sex steroids, to provide a conceptual framework with which to understand the various risk factors associated with cerebral aneurysms in women at different stages in their lives. METHODS: The PubMed database was searched for "("intracranial" OR "cerebral") AND "aneurysm" AND ("pregnancy" OR "estrogen" OR "progesterone")" between January 1980 and February 2019. A total of 392 articles were initially identified, and after applying inclusion and exclusion criteria, 20 papers were selected for review and analysis. These papers were then divided into two categories: 1) epidemiological studies about the formation, growth, rupture, and management of cerebral aneurysms in pregnancy; and 2) investigations on female sex steroids and cerebral aneurysms (animal studies and epidemiological studies). RESULTS: The 20 articles presented in this study include 7 epidemiological articles on pregnancy and cerebral aneurysms, 3 articles reporting case series of cerebral aneurysms treated by endovascular therapies in pregnancy, 3 epidemiological articles reporting the relationship between female sex steroids and cerebral aneurysms through retrospective case-control studies, and 7 experimental studies using animal and/or cell models to understand the relationship between female sex steroids and cerebral aneurysms. The studies in this review report similar risk of aneurysm rupture in pregnant women compared to the general population. Most ruptured aneurysms in pregnancy occur during the 3rd trimester, and most pregnant women who present with cerebral aneurysm have caesarean section deliveries. Endovascular treatment of cerebral aneurysms in pregnancy is shown to provide a new and safe form of therapy for these cases. Epidemiological studies of postmenopausal women show that estrogen hormone therapy and later age at menopause are associated with a lower risk of cerebral aneurysm than in matched controls. Experimental studies in animal models corroborate this epidemiological finding; estrogen deficiency causes endothelial dysfunction and inflammation, which may predispose to the formation and rupture of cerebral aneurysms, while exogenous estrogen treatment in this population may lower this risk. CONCLUSIONS: The aim of this work is to equip the neurosurgical and obstetrical/gynecological readership with the tools to better understand, critique, and apply findings from research on sex differences in cerebral aneurysms.

Role of diet-related factors in cerebral aneurysm formation and rupture

Cerebral aneurysms (CAs) are dilations of the wall of an artery in the brain filled with blood. The prevalence of unrupted CA in general population is estimated at approximately 3%. Ruptured aneurysms are the cause of 85% of spontaneous subarachnoid hemorrhage (SAH) cases. The formation of cerebral aneurysms results from various factors, including chronic inflammation, hemodynamic stress and vascular wall remodeling. Reactive oxygen species may induce the endothelial dysfunction possibly through the activation of Nuclear Factor Kappa-B, which is a key regulator of the proinflammatory genes. Hypertension may additionally increase the hemodynamic stress and activate the local renin-angiotensin system. The aim of this review was to assess the role of selected diet-related factors in the formation and rupture of cerebral aneurysms. It appears that inadequate intake of dietary antioxidants, hyperhomocysteinemia, hypertension (including incidental elevated blood pressure) and alcohol consumption may increase the risk of intracranial aneurysms. Individuals at high risk of CA formation and/or rupture should consume adequate amounts of antioxidant vitamins (vitamin C, vitamin E and carotenoids), B vitamins (vitamin B6, vitamin B12 and folate), flavonoids and n-3 fatty acids, limit alcohol and caffeine consumption and regularly control their blood pressure. Vegetables, fruits, grains, pulses, nuts and fish, as well as herbs, spices and tea, should be the major components of the daily diet. Due to the synergistic effect of various dietary components on health, Mediterranean diet or Dietary Approach to Stop Hypertension (DASH) diet, as they meet abovementioned requirements and have high anti-inflammatory potential, are thus recommended for the prevention of cerebral aneurysm formation and rupture.

Atorvastatin Protects Against Cerebral Aneurysmal Degenerative Pathology by Promoting Endothelial Progenitor Cells (EPC) Mobilization and Attenuating Vascular Deterioration in a Rat Model.

BACKGROUND Endothelial injury is the early pathological change of cerebral aneurysm (CA) formation. In addition to its lipid-lowering activity, atorvastatin (ATR) also reportedly promotes vascular repair via mobilizing endothelial progenitor cells (EPC). Here, we investigated the influence of ATR on vascular worsening after CA induction in rats. MATERIAL AND METHODS Adult male Sprague-Dawley rats were randomly assigned to 3 groups: a control (CTR) group, a CA group, and a CA+ATR treatment group. Circulating EPC level and hematological and lipid profiles were measured 3 months after CA induction. Verhoeff-Van Gieson staining and transmission electron microscopy were performed to assess pathological changes in the artery wall. RT-PCR was also performed to evaluate the expression of inflammation-related genes in the aneurysmal wall. RESULTS ATR significantly restored the impaired level of circulating EPC without changing hematological and lipid profiles 3 months after CA induction. ATR markedly inhibited endothelial injury, media thinning, and CA enlargement, accompanied by reduced vascular inflammation. CONCLUSIONS Our preliminary results demonstrate that the mobilization of EPC and improvement of endothelial function by ATR contribute to the prevention of cerebral aneurysm. Further studies are warranted to investigate the detailed mechanism.

Aneurysmal Subarachnoid Hemorrhage: Unanswered Questions.

Optimizing outcomes after aneurysmal subarachnoid hemorrhage remains a challenge for neurosurgeons and neurointensivists alike. Although we have learned a lot about the pathophysiology of this disease, many clinical questions are still unanswered. In this review, the authors discuss some of these questions, including the current diagnostic value of lumbar puncture in patients with negative computed tomography scans, the treatment value of blood pressure reduction and antifibrinolytics for prevention of early rebleeding, the indication for antiseizure medications, the optimal management of hydrocephalus and intracranial pressure, the role of clipping, and the options for diagnosis and treatment of delayed cerebral ischemia.

Cigarette Smoke Initiates Oxidative Stress-Induced Cellular Phenotypic Modulation Leading to Cerebral Aneurysm Pathogenesis.

OBJECTIVE: Cigarette smoke exposure (CSE) is a risk factor for cerebral aneurysm (CA) formation, but the molecular mechanisms are unclear. Although CSE is known to contribute to excess reactive oxygen species generation, the role of oxidative stress on vascular smooth muscle cell (VSMC) phenotypic modulation and pathogenesis of CAs is unknown. The goal of this study was to investigate whether CSE activates a NOX (NADPH oxidase)-dependent pathway leading to VSMC phenotypic modulation and CA formation and rupture. APPROACH AND RESULTS: In cultured cerebral VSMCs, CSE increased expression of NOX1 and reactive oxygen species which preceded upregulation of proinflammatory/matrix remodeling genes (MCP-1, MMPs [matrix metalloproteinase], TNF-α, IL-1ß, NF-κB, KLF4 [Kruppel-like factor 4]) and downregulation of contractile genes (SM-α-actin [smooth muscle α actin], SM-22α [smooth muscle 22α], SM-MHC [smooth muscle myosin heavy chain]) and myocardin. Inhibition of reactive oxygen species production and knockdown of NOX1 with siRNA or antisense decreased CSE-induced upregulation of NOX1 and inflammatory genes and downregulation of VSMC contractile genes and myocardin. p47phox-/- NOX knockout mice, or pretreatment with the NOX inhibitor, apocynin, significantly decreased CA formation and rupture compared with controls. NOX1 protein and mRNA expression were similar in p47phox-/- mice and those pretreated with apocynin but were elevated in unruptured and ruptured CAs. CSE increased CA formation and rupture, which was diminished with apocynin pretreatment. Similarly, NOX1 protein and mRNA and reactive oxygen species were elevated by CSE, and in unruptured and ruptured CAs. CONCLUSIONS: CSE initiates oxidative stress-induced phenotypic modulation of VSMCs and CA formation and rupture. These molecular changes implicate oxidative stress in the pathogenesis of CAs and may provide a potential target for future therapeutic strategies.

The predictive role of health-promoting behaviours and perceived stress in aneurysmal rupture.

AIMS AND OBJECTIVES: To examine the roles of two modifiable factors-health-promoting behaviours and perceived stress-in predicting aneurysmal rupture. BACKGROUND: Unruptured intracranial aneurysm detection produces significant stress and anxiety in patients because of the risk of rupture. Compared to nonmodifiable risk factors for rupture such as age, gender and aneurysm size/location, less attention has been given to modifiable risk factors. Two modifiable factors, health-promoting behaviours and perceived stress, have hardly been examined as potential predictors of rupture. DESIGN: This study used a cross-sectional design. METHODS: We assessed 155 patients with intracranial aneurysms-that is, subarachnoid haemorrhage (n = 77) or unruptured intracranial aneurysm (n = 78)-to examine (i) baseline characteristics (patient and aneurysmal factors), (ii) health-related factors (lifestyle habits and health-promoting behaviour) and (iii) perceived stress levels (psychological stress and physical stress). Patient records provided medical histories and aneurysmal factors; other data were collected using a structured questionnaire addressing lifestyle habits, the Health-Promoting Lifestyle Profile-II to measure health-promoting behaviour and the Perceived Stress Questionnaire to measure perceived-psychological stress and perceived-physical stress levels. RESULTS: Bivariate analysis indicated that aneurysm rupture risk was associated with female gender, aneurysm size/location, defecation frequency, hyperlipidaemia, sedentary time, low Health-Promoting Lifestyle Profile-II mean scores and high perceived-psychological stress scores. After adjusting for known risk factors, the mean Health-Promoting Lifestyle Profile-II and perceived-psychological stress scores remained robust predictors of rupture. Furthermore, known risk factors combined with these scores had greater predictive power than known risk factors alone. CONCLUSION: Health-promoting behaviour and psychological stress are promising modifiable factors for reducing risk of aneurysmal rupture. RELEVANCE TO CLINICAL PRACTICE: Our findings may stimulate greater understanding of mechanisms underlying aneurysmal rupture and suggest practical strategies for nurses to employ in optimising conservative management of rupture risk by teaching patients how to modify their risk. Both health-promoting behaviour and perceived stress should be addressed when designing preventive nursing interventions for patients with unruptured intracranial aneurysm.

Dipeptidyl Peptidase-4 Inhibitor Anagliptin Prevents Intracranial Aneurysm Growth by Suppressing Macrophage Infiltration and Activation.

BACKGROUND: Chronic inflammation plays a key role in the pathogenesis of intracranial aneurysms (IAs). DPP-4 (dipeptidyl peptidase-4) inhibitors have anti-inflammatory effects, including suppressing macrophage infiltration, in various inflammatory models. We examined whether a DPP-4 inhibitor, anagliptin, could suppress the growth of IAs in a rodent aneurysm model. METHODS AND RESULTS: IAs were surgically induced in 7-week-old male Sprague Dawley rats, followed by oral administration of 300 mg/kg anagliptin. We measured the morphologic parameters of aneurysms over time and their local inflammatory responses. To investigate the molecular mechanisms, we used lipopolysaccharide-treated RAW264.7 macrophages. In the anagliptin-treated group, aneurysms were significantly smaller 2 to 4 weeks after IA induction. Anagliptin inhibited the accumulation of macrophages in IAs, reduced the expression of MCP-1 (monocyte chemotactic protein 1), and suppressed the phosphorylation of p65. In lipopolysaccharide-stimulated RAW264.7 cells, anagliptin treatment significantly reduced the production of tumor necrosis factor α, MCP-1, and IL-6 (interleukin 6) independent of GLP-1 (glucagon-like peptide 1), the key mediator in the antidiabetic effects of DPP-4 inhibitors. Notably, anagliptin activated ERK5 (extracellular signal-regulated kinase 5), which mediates the anti-inflammatory effects of statins, in RAW264.7 macrophages. Preadministration with an ERK5 inhibitor blocked the inhibitory effect of anagliptin on MCP-1 and IL-6 expression. Accordingly, the ERK5 inhibitor also counteracted the suppression of p65 phosphorylation in vitro. CONCLUSIONS: A DPP-4 inhibitor, anagliptin, prevents the growth of IAs via its anti-inflammatory effects on macrophages.

Human Mesenchymal Stem Cell-Derived Microvesicles Prevent the Rupture of Intracranial Aneurysm in Part by Suppression of Mast Cell Activation via a PGE2-Dependent Mechanism.

Activation of mast cells participates in the chronic inflammation associated with cerebral arteries in intracranial aneurysm formation and rupture. Several studies have shown that the anti-inflammatory effect of mesenchymal stem cells (MSCs) is beneficial for the treatment of aneurysms. However, some long-term safety concerns exist regarding stem cell-based therapy for clinical use. We investigated the therapeutic potential of microvesicles (MVs) derived from human MSCs, anuclear membrane bound fragments with reparative properties, in preventing the rupture of intracranial aneurysm in mice, particularly in the effect of MVs on mast cell activation. Intracranial aneurysm was induced in C57BL/6 mice by the combination of systemic hypertension and intrathecal elastase injection. Intravenous administration of MSC-derived MVs on day 6 and day 9 after aneurysm induction significantly reduced the aneurysmal rupture rate, which was associated with reduced number of activated mast cells in the brain. A23187-induced activation of both primary cultures of murine mast cells and a human mast cell line, LAD2, was suppressed by MVs treatment, leading to a decrease in cytokine release and tryptase and chymase activities. Upregulation of prostaglandin E2 (PGE2) production and E-prostanoid 4 (EP4) receptor expression were also observed on mast cells with MVs treatment. Administration of an EP4 antagonist with the MVs eliminated the protective effect of MVs against the aneurysmal rupture in vivo. Human MSC-derived MVs prevented the rupture of intracranial aneurysm, in part due to their anti-inflammatory effect on mast cells, which was mediated by PGE2 production and EP4 activation. Stem Cells 2016;34:2943-2955.