Genetics of Intracranial Aneurysms

Exploring the latest findings on endovascular treatments for giant aneurysms: a review

Giant intracranial aneurysms represent a very challenging aspect of aneurysmal pathophysiology with very high mortality and morbidity if left untreated. Their variety in clinical presentation (subarachnoid hemorrhage, cranial nerve palsy, etc.) and pathological and imaging properties (location, anatomy, presence of collateral circulation) pose serious questions regarding the best treatment option. Admirable advances have been achieved in surgical techniques, while endovascular modalities with flow diversion techniques have become widely used. However, there is still lack of data regarding whether a single endovascular technique can be the universal treatment for such cases. In this review, we aim to summarize the current funds of knowledge concerning giant intracranial aneurysms and the role of endovascular management in their treatment.

ARISE I Consensus Review on the Management of Intracranial Aneurysms

BACKGROUND

Intracranial aneurysms (IAs) remain a challenging neurological diagnosis associated with significant morbidity and mortality. There is a plethora of microsurgical and endovascular techniques for the treatment of both ruptured and unruptured aneurysms. There is no definitive consensus as to the best treatment option for this cerebrovascular pathology. The Aneurysm, Arteriovenous Malformation, and Chronic Subdural Hematoma Roundtable Discussion With Industry and Stroke Experts discussed best practices and the most promising approaches to improve the management of brain aneurysms.

METHODS

A group of experts from academia, industry, and federal regulators convened to discuss updated clinical trials, scientific research on preclinical system models, management options, screening and monitoring, and promising novel device technologies, aiming to improve the outcomes of patients with IA.

RESULTS

Aneurysm, Arteriovenous Malformation, and Chronic Subdural Hematoma Roundtable Discussion With Industry and Stroke Experts suggested the incorporation of artificial intelligence to capture sequential aneurysm growth, identify predictors of rupture, and predict the risk of rupture to guide treatment options. The consensus strongly recommended nationwide systemic data collection of unruptured IA radiographic images for the analysis and development of machine learning algorithms for rupture risk. The consensus supported centers of excellence for preclinical multicenter trials in areas such as genetics, cellular composition, and radiogenomics. Optical coherence tomography and magnetic resonance imaging contrast-enhanced 3T vessel wall imaging are promising technologies; however, more data are needed to define their role in IA management. Ruptured aneurysms are best managed at large volume centers, which should include comprehensive patient management with expertise in microsurgery, endovascular surgery, neurology, and neurocritical care.

CONCLUSIONS

Clinical and preclinical studies and scientific research on IA should engage high-volume centers and be conducted in multicenter collaborative efforts. The future of IA diagnosis and monitoring could be enhanced by the incorporation of artificial intelligence and national radiographic and biologic registries. A collaborative effort between academic centers, government regulators, and the device industry is paramount for the adequate management of IA and the advancement of the field.

Complex networks approach to study comorbidities in patients with unruptured intracranial aneurysms

The role of complex network analysis in patients with diagnosis of unruptured intracranial aneurysm is unexplored. The objective of this study is to assess the applicability of this methodology in aneurysm patients. We retrospectively analyze comprehensive unbiased local digital data of a large number of patients treated for any reason between January 2004 and July 2019. We apply an age-cohort approach to a total of 628,831 patients and construct the diagnostic history of each patient-and include the information how old the patient was when diagnosed for the first time with each diagnosis coded according to International Classification of Diseases. For each cohort of age within a 10 year interval and for each gender, we construct a statistically validated comorbidity network and focused on crucial comorbidity links that the aneurysm code has to other disease codes within the whole network. For all cohorts of different age and gender, the analysis shows that 267 diagnose codes have nearest neighbour statistically validated links to unruptured aneurysm ICD code. Among the 267 comorbidities, 204 (76%) were found in patients aged from 40 to 69-years old. Patterns of connectivity with aneurysms were found for smoking, hypertension, chronic obstructive pulmonary disease, dyslipidemia, and mood disorders. A few uncommon connections are also detected in cohorts of female patients. Our study explored the applicability of network analysis and statistical validation in aneurysm observational study.

Exploring the potential of VGLL3 methylation as a prognostic indicator for intracranial aneurysm with gender-specific considerations

DNA methylation is widely recognized to play a role in intracranial aneurysm (IA) pathogenesis. We investigated the levels of methylation of vestigial-like 3 (VGLL3) in IA and explored its potential as a prognostic indicator. A total of 48 patients with IA and 48 healthy controls were included in the present study. Methylation levels of CpG sites were assessed using bisulfite pyrosequencing, and levels of VGLL3, TEAD, and YAP in the blood were measured by real-time quantitative polymerase chain reaction testing. VGLL3 methylation was significantly higher in controls than in IA patients (P=0.001), and this phenomenon was more pronounced in females (P<0.001). Compared with the control group, the expression levels of VGLL3 and TEAD in the blood of IA patients were significantly increased, while YAP was significantly decreased. VGLL3 methylation was positively correlated with HDL (P=0.003) and female Lpa concentration (r = 0.426, P=0.03), and was also negatively correlated with age (P=0.003), APOE (P=0.005), and VGLL3 mRNA expression (P<0.001). Methylation and mRNA expression of VGLL3 may serve as indicators of IA risk in females (AUC = 0.810 and 0.809). VGLL3 methylation may participate in the pathogenesis of IA by regulating the expression of the VGLL3/TEAD/YAP pathway, and its gene methylation and expression levels have IA risk prediction value.

ADORA3: A Key Player in the Pathogenesis of Intracranial Aneurysms and a Potential Diagnostic Biomarker

BACKGROUND

The effects of genes on the development of intracranial aneurysms (IAs) remain to be elucidated, and reliable blood biomarkers for diagnosing IAs are yet to be established. This study aimed to identify genes associated with IAs pathogenesis and explore their diagnostic value by analyzing IAs datasets, conducting vascular smooth muscle cells (VSMC) experiments, and performing blood detection.

METHODS

IAs datasets were collected and the differentially expressed genes were analyzed. The selected genes were validated in external datasets. Autophagy was induced in VSMC and the effect of selected genes was determined. The diagnostic value of selected gene on the IAs were explored using area under curve (AUC) analysis using IAs plasma samples.

RESULTS

Analysis of 61 samples (32 controls and 29 IAs tissues) revealed a significant increase in expression of ADORA3 compared with normal tissues using empirical Bayes methods of "limma" package; this was further validated by two external datasets. Additionally, induction of autophagy in VSMC lead to upregulation of ADORA3. Conversely, silencing ADORA3 suppressed VSMC proliferation and autophagy. Furthermore, analysis of an IAs blood sample dataset and clinical plasma samples demonstrated increased ADORA3 expression in patients with IA compared with normal subjects. The diagnostic value of blood ADORA3 expression in IAs was moderate when analyzing clinical samples (AUC: 0.756). Combining ADORA3 with IL2RB or CCR7 further enhanced the diagnostic ability for IAs, with the AUC value over 0.83.

CONCLUSIONS

High expression of ADORA3 is associated with IAs pathogenesis, likely through its promotion of VSMC autophagy. Furthermore, blood ADORA3 levels have the potential to serve as an auxiliary diagnostic biomarker for IAs.

Drug classes affecting intracranial aneurysm risk: Genetic correlation and Mendelian randomization

INTRODUCTION

There is no non-invasive treatment to prevent aneurysmal subarachnoid hemorrhage (ASAH) caused by intracranial aneurysm (IA) rupture. We aimed to identify drug classes that may affect liability to IA using a genetic approach.

PATIENTS AND METHODS

Using genome-wide association summary statistics we calculated genetic correlation between unruptured IA (N = 2140 cases), ASAH (N = 5140) or the combined group, and liability to drug usage from 23 drug classes (N up to 320,000) independent of the risk factor high blood pressure. Next, we evaluated the causality and therapeutic potential of correlated drug classes using three different Mendelian randomization frameworks.

RESULTS

Correlations with IA were found for antidepressants, paracetamol, acetylsalicylic acid, opioids, beta-blockers, and peptic ulcer and gastro-esophageal reflux disease drugs. MR showed no evidence that genetically predicted usage of these drug classes caused IA. Genetically predicted high responders to antidepressant drugs were at higher risk of IA (odds ratio [OR] = 1.61, 95% confidence interval (CI) = 1.09-2.39, p = 0.018) and ASAH (OR = 1.68, 95% CI = 1.07-2.65, p = 0.024) if they used antidepressant drugs. This effect was absent in non-users. For beta-blockers, additional analyses showed that this effect was not independent of blood pressure after all. A complex and likely pleiotropic relationship was found between genetic liability to chronic multisite pain, pain medication usage (paracetamol, acetylsalicylic acid, and opioids), and IA.

CONCLUSIONS

We did not find drugs decreasing liability to IA and ASAH but found that antidepressant drugs may increase liability. We observed pleiotropic relationships between IA and other drug classes and indications. Our results improve understanding of pathogenic mechanisms underlying IA.

Peripheral macrophages in the development and progression of structural cerebrovascular pathologies

The human cerebrovascular system is responsible for maintaining neural function through oxygenation, nutrient supply, filtration of toxins, and additional specialized tasks. While the cerebrovascular system has resilience imparted by elaborate redundant collateral circulation from supportive tertiary structures, it is not infallible, and is susceptible to developing structural vascular abnormalities. The causes of this class of structural cerebrovascular diseases can be broadly categorized as 1) intrinsic developmental diseases resulting from genetic or other underlying aberrations (arteriovenous malformations and cavernous malformations) or 2) extrinsic acquired diseases that cause compensatory mechanisms to drive vascular remodeling (aneurysms and arteriovenous fistulae). Cerebrovascular diseases of both types pose significant risks to patients, in some cases leading to death or disability. The drivers of such diseases are extensive, yet inflammation is intimately tied to all of their progressions. Central to this inflammatory hypothesis is the role of peripheral macrophages; targeting this critical cell type may lead to diagnostic and therapeutic advancement in this area. Here, we comprehensively review the role that peripheral macrophages play in cerebrovascular pathogenesis, provide a schema through which macrophage behavior can be understood in cerebrovascular pathologies, and describe emerging diagnostic and therapeutic avenues in this area.

Analysis of aneurysmal subarachnoid hemorrhage as a multistep process

BACKGROUND AND PURPOSE

Aneurysmal subarachnoid hemorrhage (ASAH) is a complex disease with higher incidence in women compared to men and in Japan compared to other countries. It was hypothesized that ASAH is consistent with a multistep model of disease. The following assessments were made: (1) the number of steps needed for the disease to occur and (2) whether this number may be different in female versus male and in Japanese versus non-Japanese patients.

METHODS

Incidence data were generated from a meta-analysis on ASAH incidence until 2017, which was supplemented with a literature search from 2017 to April 2023. Age- and sex-adjusted incidences per 10-year age groups were calculated and the logarithm of age-specific incidence against the logarithm of age was regressed with least-squares regression.

RESULTS

In 2317 ASAH patients a linear relationship between logarithm of incidence and logarithm of age was found with a slope estimate of 3.13 (95% confidence interval 2.60-3.65), consistent with a four-step process. Similar estimates were found for female, male, Japanese and non-Japanese patients.

CONCLUSIONS

Our results suggest that ASAH is a four-step process, also in subgroups with higher ASAH incidence. Elucidation of the exact nature of these steps can provide important clues for identification of disease mechanisms underlying ASAH.

Monogenic Causes of Cerebrovascular Disease in Childhood: A Case Series

BACKGROUND

Despite an increase in the number of genes associated with pediatric stroke, imaging phenotypes in children have not been well reported. Guidelines are needed to facilitate the identification and treatment of patients with monogenic causes of cerebrovascular disorders.

METHODS

We performed a retrospective review of imaging and medical records of patients aged zero to 21 years with monogenic causes of vascular malformations, small or large vessel disease, transient ischemic attacks, and/or ischemic or hemorrhagic stroke. We classified patients according to their imaging phenotype and reviewed neurological and systemic features and management strategies. We reviewed the literature to identify genes associated with cerebrovascular disorders presenting in childhood.

RESULTS

We identified 18 patients with monogenic causes of cerebrovascular disorders and classified each patient as belonging to one or more of three cerebrovascular phenotypes according to predominant imaging characteristics: small vessel disease, large vessel disease, and/or vascular malformations. Preventative treatments included aspirin, N-acetylcysteine, tocilizumab, therapeutic low-molecular-weight heparin, and resection of vascular malformations.

CONCLUSIONS

Classifying pediatric patients with cerebrovascular disorders by imaging phenotype can aid in determining the next steps in genetic testing and treatment.

Light at the ENDothelium-role of Sox17 and Runx1 in endothelial dysfunction and pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a progressive disease that is characterized by an obliterative vasculopathy of the distal pulmonary circulation. Despite significant progress in our understanding of the pathophysiology, currently approved medical therapies for PAH act primarily as pulmonary vasodilators and fail to address the underlying processes that lead to the development and progression of the disease. Endothelial dysregulation in response to stress, injury or physiologic stimuli followed by perivascular infiltration of immune cells plays a prominent role in the pulmonary vascular remodeling of PAH. Over the last few decades, our understanding of endothelial cell dysregulation has evolved and brought to light a number of transcription factors that play important roles in vascular homeostasis and angiogenesis. In this review, we examine two such factors, SOX17 and one of its downstream targets, RUNX1 and the emerging data that implicate their roles in the pathogenesis of PAH. We review their discovery and discuss their function in angiogenesis and lung vascular development including their roles in endothelial to hematopoietic transition (EHT) and their ability to drive progenitor stem cells toward an endothelial or myeloid fate. We also summarize the data from studies that link mutations in Sox17 with an increased risk of developing PAH and studies that implicate Sox17 and Runx1 in the pathogenesis of PAH. Finally, we review the results of recent studies from our lab demonstrating the efficacy of preventing and reversing pulmonary hypertension in animal models of PAH by deleting RUNX1 expression in endothelial or myeloid cells or by the use of RUNX1 inhibitors. By investigating PAH through the lens of SOX17 and RUNX1 we hope to shed light on the role of these transcription factors in vascular homeostasis and endothelial dysregulation, their contribution to pulmonary vascular remodeling in PAH, and their potential as novel therapeutic targets for treating this devastating disease.

Rare variants with large effects provide functional insights into the pathology of migraine subtypes, with and without aura

Migraine is a complex neurovascular disease with a range of severity and symptoms, yet mostly studied as one phenotype in genome-wide association studies (GWAS). Here we combine large GWAS datasets from six European populations to study the main migraine subtypes, migraine with aura (MA) and migraine without aura (MO). We identified four new MA-associated variants (in PRRT2, PALMD, ABO and LRRK2) and classified 13 MO-associated variants. Rare variants with large effects highlight three genes. A rare frameshift variant in brain-expressed PRRT2 confers large risk of MA and epilepsy, but not MO. A burden test of rare loss-of-function variants in SCN11A, encoding a neuron-expressed sodium channel with a key role in pain sensation, shows strong protection against migraine. Finally, a rare variant with cis-regulatory effects on KCNK5 confers large protection against migraine and brain aneurysms. Our findings offer new insights with therapeutic potential into the complex biology of migraine and its subtypes.

Spontaneous Middle Meningeal Artery Aneurysms: A Case Report and Review of the Literature

Most reported aneurysms concerning the middle meningeal artery (MMA) are pseudoaneurysms; however, there have been rare reports of non-traumatic MMA aneurysms in the literature. In this paper, we present the case of a 70-year-old female with a true 5-mm aneurysm in the anterior division of the left MMA that was causing erosion through the left temporal bone and was successfully treated with coil embolization. We also present a comprehensive literature review of non-traumatic MMA aneurysms reported since 1930. These aneurysms are associated with conditions such as hypertension, Paget's disease, and intracranial meningiomas and result from flow dynamics disturbances. Treatment involves both endovascular treatment and open surgery, while rupture, especially in the elderly, results in high disability, underscoring the importance of timely intervention upon identification.

ICGA combined with EP monitoring in microclipping of cerebral aneurysms

Cerebral aneurysm is one of the common cerebrovascular diseases in neurosurgery, and rupture of cerebral aneurysm is the most important cause of spontaneous subarachnoid hemorrhage. How to precisely clip the aneurysm has been a topic worth discussing, so the authors explore the value of ICGA combined with electrophysiological monitoring in the microclipping of cerebral aneurysms. Using the method of retrospective analysis of cases, 661 patients with cerebral aneurysms admitted to the Department of Neurosurgery, Zhongnan Hospital of Wuhan University, from 2021.8 to 2022.10 were studied, 390 patients with aneurysm clipping were included, and patients with Hunt-Hess classification ≥ 4 were excluded, and whether to use ICGA combined with EP in microclipping of the ruptured and unruptured aneurysm in pterional approach was investigated at the time of discharge, respectively. The MRS and total hospital days were compared to investigate the value of ICGA combined with EP in the microclipping of cerebral aneurysms. All 390 patients enrolled in the group had successful aneurysm clipping, 178 patients were screened for ruptured aneurysm pterional approach and 120 patients for unruptured aneurysm pterional approach access; the MRS at discharge was significantly lower in the ICGA combined with EP group than in the no-EP group for ruptured aneurysm pterional approach microclipping (p < 0.001), and the mean number of days in hospital was significantly lower (p < 0.01). Patients in the ICGA combined with EP group in microclipping of unruptured aneurysms with pterional approach also had significantly lower MRS at discharge compared with patients in the ICGA alone group (p < 0.001), with no statistically significant difference in the mean number of days in hospital (p = 0.09). In open cerebral aneurysm microclipping, ICGA combined with EP monitoring for both ruptured and unruptured aneurysms can effectively reduce the false-negative rate of ICGA, significantly reduce the incidence of postoperative neurological deficits, and shorten the total hospital stay to some extent. ICGA combined with EP monitoring may be an effective means to reduce the rate of false clipping of the penetrating vessels and to avoid stenosis or occlusion of the aneurysm-carrying artery and is worth promoting in microclipping of cerebral aneurysms except for Hunt-Hess ≥ 4.

Vascular Complications in Autosomal Dominant Polycystic Kidney Disease: Perspectives, Paradigms, and Current State of Play

Autosomal dominant polycystic kidney disease (ADPKD) is the leading cause of inherited kidney disease with significant contributions to CKD and end-stage kidney disease. The underlying polycystin proteins (PC1 and PC2) have widespread tissue expression and complex functional roles making ADPKD a systemic disease. Vascular complications, particularly intracranial aneurysms (ICA) are the most feared due to their potential for devastating neurological complications and sudden death. Intracranial aneurysms occur in 8-12% of all patients with ADPKD, but the risk is intensified 4-5-fold in those with a positive family history. The basis for this genetic risk is not well understood and could conceivably be due to features of the germline mutation with a significant contribution of other genetic modifiers and/or environmental factors. Here we review what is known about the natural history and genetics of unruptured ICA in ADPKD including the prevalence and risk factors for aneurysm formation and subarachnoid hemorrhage. We discuss two alternative screening strategies and recommend a practical algorithm that targets those at highest risk for ICA with a positive family history for screening.

Morphology and Hemodynamics of Cerebral Arteries and Aneurysms in a Rare Pair of Monozygotic Twins

In this preliminary study, the underlying pathophysiology mechanisms of cerebral aneurysms (CAs) in monozygotic twins (MTs) were investigated via a rare pair of MTs (twin A and twin B) involving four reconstructed arterial models using preclinical information. First, dimensions and configurated outlines of three-perspective geometries were compared. Adopting an in-vitro validated numerical CA model, hemodynamic characteristics were investigated in the MTs, respectively. Despite expected genetic similarities, morphological comparisons show that configurations of cerebral arteries exhibit significant differences between the twins. The ICA size of twin A is larger than that in twin B (2.23~25.86%), varying with specific locations, attributing to variations during embryological developments and environmental influences. Numerical modeling indicates the MTs have some hemodynamic similarities such as pressure distributions (~13,400 Pa) and their oscillatory shear index (OSI) (0~0.49), but present significant differences in local regions. Specifically, the difference in blood flow rate in the MTs is from 16% to 221%, varying with specifically compared arteries. The maximum time-averaged wall shear stress (53.6 Pa vs. 37.8 Pa) and different local OSI distributions were also observed between the MTs. The findings revealed that morphological variations in MTs could be generated by embryological and environmental factors, further influencing hemodynamic characteristics on CA pathophysiology.

Vascular smooth muscle cells in intracranial aneurysms

Intracranial aneurysm (IA) is a severe cerebrovascular disease characterized by abnormal bulging of cerebral vessels that may rupture and cause a stroke. The expansion of the aneurysm accompanies by the remodeling of vascular matrix. It is well-known that vascular remodeling is a process of synthesis and degradation of extracellular matrix (ECM), which is highly dependent on the phenotype of vascular smooth muscle cells (VSMCs). The phenotypic switching of VSMC is considered to be bidirectional, including the physiological contractile phenotype and alternative synthetic phenotype in response to injury. There is increasing evidence indicating that VSMCs have the ability to switch to various phenotypes, including pro-inflammatory, macrophagic, osteogenic, foamy and mesenchymal phenotypes. Although the mechanisms of VSMC phenotype switching are still being explored, it is becoming clear that phenotype switching of VSMCs plays an essential role in IA formation, progression, and rupture. This review summarized the various phenotypes and functions of VSMCs associated with IA pathology. The possible influencing factors and potential molecular mechanisms of the VSMC phenotype switching were further discussed. Understanding how phenotype switching of VSMC contributed to the pathogenesis of unruptured IAs can bring new preventative and therapeutic strategies for IA.

Will improved neuroradiology facilities debunk the reported rarity of intracranial aneurysms in Sub-Saharan Africa?

Background:

Intracranial aneurysms (IAN) are rare in the Sub-Saharan Africa unlike other parts of the world. The debate is whether the low frequency might be apparent because of the scarcity of advanced neuroimaging services, or real. This study investigated if improved imaging facilities would debunk the rarity of IAN in our subregion.

Methods:

This is a retrospective cohort study of prospectively recorded data of patients with subarachnoid hemorrhage (SAH) and IAN managed over 19 years (2003–2021), at the study center with a catchment population of over 47 million. The center witnessed progressive improvements in neuroimaging facilities: 2-Slice, 8-slice, and 64-slice computed tomography (CT) and 0.35T, 1.5T magnetic resonance imaging (MRI) during the period.

Results:

There were 241 cases of SAH, but only 166 aneurysms were confirmed in 158 patients. Between 2003 and 2008, only 27 IAN patients (4.5 IAN/year) were diagnosed. After introduction of CT angiography/magnetic resonance angiography MRA using 8-slice CT/0.35T magnetic resonance imaging (MRI), between 2009 and 2014, the frequency of IAN increased to 8/year. Between 2015 and 2018 after installation of a 64-slice CT in 2014, the IAN remained the same (8/year). MRI 1.5T was added in 2018, the frequency doubled to 17 cases/year. The females were more (67.7%), the mean age was 46.3 years, but peak incidence was the sixth decade. Internal carotid artery aneurysms including posterior communicating artery were the most common (43%) followed by ACA with anterior communicating artery (24%) and middle cerebral artery (20%). Multiple aneurysms were seen in ten patients.

Conclusion:

Improved neuroimaging between 2003 and 2021 did not debunk the rarity of IAN in our region.

Pathophysiology of Early Brain Injury and Its Association with Delayed Cerebral Ischemia in Aneurysmal Subarachnoid Hemorrhage: A Review of Current Literature

Background: Delayed cerebral ischemia (DCI) is a common and serious complication of aneurysmal subarachnoid hemorrhage (aSAH). Though many clinical trials have looked at therapies for DCI and vasospasm in aSAH, along with reducing rebleeding risks, none have led to improving outcomes in this patient population. We present an up-to-date review of the pathophysiology of DCI and its association with early brain injury (EBI). Recent Findings: Recent studies have demonstrated that EBI, as opposed to delayed brain injury, is the main contributor to downstream pathophysiological mechanisms that play a role in the development of DCI. New predictive models, including advanced monitoring and neuroimaging techniques, can help detect EBI and improve the clinical management of aSAH patients. Summary: EBI, the severity of subarachnoid hemorrhage, and physiological/imaging markers can serve as indicators for potential early therapeutics in aSAH. The microcellular milieu and hemodynamic pathomechanisms should remain a focus of researchers and clinicians. With the advancement in understanding the pathophysiology of DCI, we are hopeful that we will make strides toward better outcomes for this unique patient population.

DNA methylation and mRNA expression of glutathione S-transferase alpha 4 are associated with intracranial aneurysms in a gender-dependent manner

Objective: We performed a case-control study to investigate the correlation between DNA methylation and mRNA expression of the glutathione S-transferase alpha 4 (GSTA4) gene and the risk of intracranial aneurysm (IA) in the Chinese Han population. Methods: After propensity score matching, 44 pairs of cases and controls were collected in this study. Fasting blood samples were collected for DNA and RNA extraction within 24 h of admission. Nine CpG dinucleotides were selected from the GSTA4 promoter region for DNA methylation pyrosequencing. mRNA expression of GSTA4 was measured by quantitative real-time polymerase chain reaction (RT-qPCR). In vitro cell experiments were conducted to verify the association between 5-aza-2'-deoxycytidine induced DNA hypomethylation and GSTA4 mRNA expression. Results: The mean methylation level of GSTA4 was much lower in IA patients, especially in IA patients, especially in unruptured IA (UIA), than that in controls (IA vs. Control, p < .001; ruptured IA (RIA) vs. Control, p = .005; UIA vs. Control, p < .001). With sex stratification, we further found that the association between GSTA4 methylation and IA risk presented only in women (mean methylation level: IA vs. Control, p < .001; RIA vs. Control, p = .009; UIA vs. Control, p < .001). GSTA4 mRNA expression was significantly higher in the IA group than in the control group (p < .01) and negatively correlated with DNA methylation in all individuals (r = -.746, p < .001). DNA hypomethylation can increase GSTA4 mRNA expression in human primary artery smooth muscle cells. The receiver operating characteristic (ROC) curve showed that GSTA4 mean methylation (AUC = .80, p < .001) was a reliable predictor of women intracranial aneurysm, among which CpG 1 exhibited the best predictive value (AUC = .89, p < .001). In addition, GSTA4 expression levels could also predict the risk of IA in women (AUC = .87, p = .005). Conclusion: Decreased DNA methylation and increased mRNA expression of the GSTA4 gene are associated with the risk of IA in women.

Identification of Biomarkers in Intracranial Aneurysm and Their Immune Infiltration Characteristics

BACKGROUND

Intracranial aneurysm (IA), known as the intracranial "unscheduled bomb," is one of the most dangerous cerebrovascular diseases, with unclear pathogenesis. This study aimed to show the mechanisms and identify the new biological targets by applying bioinformatics analysis.

METHODS

Expression profiling for control superficial temporal artery and IA walls in GSE26969 and GSE75436 datasets were downloaded. By executing the LIMMA package in R software, the differentially expressed genes (DEGs) were filtered, and the functional enrichments were consequently performed. Further cross-linking with the 2483 immune-related genes (IRGs) from the ImmPort database, the differentially expressed IRGs were identified. Based on them, the least absolute shrinkage and selection operator logistic regression and support vector machine-recursive feature elimination algorithms were used to screen the biomarkers, which were validated in the GSE54083 datasets. The CIBERSORT algorithm was applied to evaluate the infiltration of immune cells in tissues.

RESULTS

A total of 668 DEGs were obtained, and the functional enrichment suggested that they were closely related to the immune process. After intersecting them with the IRGs, 90 differentially expressed IRGs emerged, and ADIPOQ and ESM1 were identified as the biomarkers. Besides, we found that the infiltrated immune cells, such as the mast cells resting, might be associated with them.

CONCLUSIONS

We explored the contributing factors involving IA, which may generate a better understanding of the complex interactions among them and inspire a promising strategy for clinical works.

Multinational Genome-Wide Association Study and Functional Genomics Analysis Implicates Decreased SIRT3 Expression Underlying Intracranial Aneurysm Risk

BACKGROUND

The genetic mechanisms regulating intracranial aneurysm (IA) formation and rupture are largely unknown. To identify germline-genetic risk factors for IA, we perform a multinational genome-wide association study (GWAS) of individuals from the United Kingdom, Finland, and Japan.

OBJECTIVE

To identify a shared, multinational genetic basis of IA.

METHODS

Using GWAS summary statistics from UK Biobank, FinnGen, and Biobank Japan, we perform a meta-analysis of IA, containing ruptured and unruptured IA cases. Logistic regression was used to identify IA-associated single-nucleotide polymorphisms. Effect size was calculated using the coefficient r , estimating the contribution of the single-nucleotide polymorphism to the genetic variance of the trait. Genome-wide significance was set at 5.0 × 10 -8 . Expression quantitative trait loci mapping and functional genomics approaches were used to infer mechanistic consequences of implicated variants.

RESULTS

Our cohort contained 155 154 individuals (3132 IA cases and 152 022 controls). We identified 4 genetic loci reaching genome-wide: rs73392700 ( SIRT3 , effect size = 0.28, P = 4.3 × 10 -12 ), rs58721068 ( EDNRA , effect size = -0.20, P = 4.8 × 10 -12 ), rs4977574 ( AL359922.1 , effect size = 0.18, P = 7.9 × 10 -12 ), and rs11105337 ( ATP2B1 , effect size = -0.15, P = 3.4 × 10 -8 ). Expression quantitative trait loci mapping suggests that rs73392700 has a large effect size on SIRT3 gene expression in arterial and muscle, but not neurological, tissues. Functional genomics analysis suggests that rs73392700 causes decreased SIRT3 gene expression.

CONCLUSION

We perform a multinational GWAS of IA and identify 4 genetic risk loci, including 2 novel IA risk loci ( SIRT3 and AL359922.1 ). Identification of high-risk genetic loci across ancestries will enable population-genetic screening approaches to identify patients with IA.

Stroke Genetics: Discovery, Insight Into Mechanisms, and Clinical Perspectives

Stroke is the second leading cause of death worldwide and a complex, heterogeneous condition. In this review, we provide an overview of the current knowledge on monogenic and multifactorial forms of stroke, highlighting recent insight into the continuum between these. We describe how, in recent years, large-scale genome-wide association studies have enabled major progress in deciphering the genetic basis for stroke and its subtypes, although more research is needed to interpret these findings. We cover the potential of stroke genetics to reveal novel pathophysiological processes underlying stroke, to accelerate the discovery of new therapeutic approaches, and to identify individuals in the population who are at high risk of stroke and could be targeted for tailored preventative interventions.

Endovascular Biopsy of Vertebrobasilar Aneurysm in Patient With Polyarteritis Nodosa

Background and Purpose: The management of unruptured intracranial aneurysms remains controversial. The decisions to treat are heavily informed by estimated risk of bleeding. However, these estimates are imprecise, and better methods for stratifying the risk or tailoring treatment strategy are badly needed. Here, we demonstrate an initial proof-of-principle concept for endovascular biopsy to identify the key molecular pathways and gene expression changes associated with aneurysm formation. We couple this technique with single cell RNA sequencing (scRNAseq) to develop a roadmap of the pathogenic changes of a dolichoectatic vertebrobasilar aneurysm in a patient with polyarteritis nodosa.

Methods: Endovascular biopsy and fluorescence activated cell sorting was used to isolate the viable endothelial cells (ECs) using the established techniques. A single cell RNA sequencing (scRNAseq) was then performed on 24 aneurysmal ECs and 23 patient-matched non-aneurysmal ECs. An integrated panel of bioinformatic tools was applied to determine the differential gene expression, enriched signaling pathways, and cell subpopulations hypothesized to drive disease pathogenesis.

Results: We identify a subset of 7 (29%) aneurysm-specific ECs with a distinct gene expression signature not found in the patient-matched control ECs. A gene set enrichment analysis identified these ECs to have increased the expression of genes regulating the leukocyte-endothelial cell adhesion, major histocompatibility complex (MHC) class I, T cell receptor recycling, tumor necrosis factor alpha (TNFα) response, and interferon gamma signaling. A histopathologic analysis of a different intracranial aneurysm that was later resected yielded a diagnosis of polyarteritis nodosa and positive staining for TNFα.

Conclusions: We demonstrate feasibility of applying scRNAseq to the endovascular biopsy samples and identify a subpopulation of ECs associated with cerebral aneurysm in polyarteritis nodosa. Endovascular biopsy may be a safe method for deriving insight into the disease pathogenesis and tailoring the personalized treatment approaches to intracranial aneurysms.

Stroke Genetics: Turning Discoveries into Clinical Applications

The field of medical and population genetics in stroke is moving at a rapid pace and has led to unanticipated opportunities for discovery and clinical applications. Genome-wide association studies have highlighted the role of specific pathways relevant to etiologically defined subtypes of stroke and to stroke as a whole. They have further offered starting points for the exploration of novel pathways and pharmacological strategies in experimental systems. Mendelian randomization studies continue to provide insights in the causal relationships between exposures and outcomes and have become a useful tool for predicting the efficacy and side effects of drugs. Additional applications that have emerged from recent discoveries include risk prediction based on polygenic risk scores and pharmacogenomics. Among the topics currently moving into focus is the genetics of stroke outcome. While still at its infancy, this field is expected to boost the development of neuroprotective agents. We provide a brief overview on recent progress in these areas.