Comment on, "Differential DNA methylation associated with delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage: a systematic review".

The article "Differential DNA Methylation Associated with Delayed Cerebral Ischemia after Aneurysmal Subarachnoid Hemorrhage: A Systematic Review" by Tomasz Klepinowski et al. offers an in-depth analysis of the relationship between DNA methylation and delayed cerebral ischemia (DCI) following aneurysmal subarachnoid hemorrhage (aSAH). By systematically reviewing databases like PubMed, MEDLINE, Scopus, and Web of Science, the authors identify key genes, including ITPR3, HAMP, INSR, and CDHR5, as potential biomarkers for early DCI diagnosis. Their meticulous adherence to PRISMA guidelines and the STROBE statement for quality assessment enhances the study's credibility. However, the review could be improved by discussing methodological variability, statistical power, and the functional relevance of identified CpG sites. Additional sections on mechanistic pathways, integration with other omics data, clinical translation, and ethical considerations would further strengthen the review, providing a more comprehensive understanding of epigenetic factors in DCI and paving the way for future therapeutic interventions.

Comment on, "Gene expression in a canine basilar artery vasospasm model: a genome-wide network-based analysis".

The study by Sasahara et al. (2008) offers a comprehensive exploration of the molecular mechanisms underlying cerebral vasospasm following subarachnoid hemorrhage, utilizing genome-wide microarray technology and network-based analysis in a canine model. Their work identifies significant gene expression changes, particularly in IL-6, IL-8, and CCL2, which are implicated in cell signaling, host-pathogen interactions, and immune responses. Despite the study's methodological rigor, it is limited by a single time-point analysis and the use of non-injected controls, which may not fully account for procedural effects. Future studies should include a time-course analysis and more appropriate controls, as well as isolate specific cell types to enhance the relevance of the findings. Further research could explore therapeutic interventions targeting the identified pathways, particularly those involved in calcium signaling and inflammation, to develop more effective treatments for cerebral vasospasm.

Genetic evidence for the causal association of neuroticism with intracranial aneurysms: A Mendelian randomization study.

OBJECTIVE: The aim of this study was to assess the potential causal relationship between neuroticism and 12 neuroticism items with intracranial aneurysms (IAs) and aneurysmal subarachnoid hemorrhage (aSAH) using a two-sample Mendelian randomization (MR) approach. METHODS: Study data were obtained from the Genome-Wide Association Study (GWAS) pooled dataset, and we extracted summary statistics for neuroticism, 12 neuroticism items, and IAs, which were categorized into ruptured and unruptured aneurysms (IA), aSAH, and unruptured IAs (uIA). Single nucleotide polymorphisms (SNPs) were used as instrumental variables (IVs) to explore the causal relationship between exposure and outcome using five Mendelian randomization methods, with Inverse variance weighted (IVW) as the primary study method. Horizontal multiple validity tests, sensitivity analyses, and inverse MR ensured the stability of the results. RESULTS: The two-sample MR showed a genetically predictive association between neuroticism and IA [odds ratio (OR) = 1.16; 95 % confidence interval (95 % CI): 1.04-1.30; p = 0.009], aSAH (OR = 1.17; 95 % CI: 1.03-1.33; p = 0.013) and uIA (OR = 1.30; 95 % CI: 1.07-1.59; p = 0.009) were all genetically predictive of association. Ivw showed a positive association between 5 neuroticism items and IA risk, 5 neuroticism items and aSAH risk as well as no genetically predictive association between neuroticism items and uIA. Sensitivity analysis and inverse MR confirmed the robustness of the results. CONCLUSION: Our Mendelian randomization analysis demonstrated genetic causality between neuroticism and neuroticism items with intracranial aneurysms, aneurysmal subarachnoid hemorrhage, and unruptured intracranial aneurysms, and further studies are needed to confirm these results and explore potential mechanisms of action.

MiRNA expression profiling reveals a potential role of microRNA-148b-3p in cerebral vasospasm in subarachnoid hemorrhage.

Cerebral vasospasm (CVS) is an important contributor to delayed cerebral ischemia following aneurysmal subarachnoid hemorrhage (aSAH), leading to high morbidity and long-term disability. While several microRNAs (miRNAs) have been implicated in vasospasm, the underlying mechanisms for CVS remain poorly understood. Our study aims to identify miRNAs that may contribute to the development of CVS. Whole-blood samples were obtained during or outside of vasospasm from aSAH patients whose maximal vasospasm was moderate or severe. MiRNAs were isolated from serial whole-blood samples, and miRNA sequencing was performed. Differentially expressed miRNAs were identified and the expression levels in patients' samples were verified using real-time qPCR. The biological functions of identified miRNA were evaluated in human brain endothelial cells (HBECs). MiRNA profiling revealed significant upregulation of miR-148b-3p in patients during CVS. We demonstrated that miR-148b-3p directly targeted and decreased the expression of ROCK1, affecting cell proliferation, migration, and invasion of HBECs through the ROCK-LIMK-Cofilin pathway. We propose that the upregulation of miRNA-148b-3p plays a role in the development of CVS by regulating actin cytoskeletal dynamics in HBECs, which is crucial for vascular function. Our study highlights miR-148b-3p as a potential diagnostic marker as well as therapeutic target for CVS following aSAH.

miR-93-5p impairs autophagy-lysosomal pathway via TET3 after subarachnoid hemorrhage.

Intact autophagy-lysosomal pathway (ALP) in neuronal survival is crucial. However, it remains unclear whether ALP is intact after subarachnoid hemorrhage (SAH). Ten-eleven translocation (TET) 3 primarily regulates genes related to autophagy in neurons in neurodegenerative diseases. This study aims to investigate the role of TET3 in the ALP following SAH. The results indicate that the ALP is impaired after SAH, with suppressed autophagic flux and an increase in autophagosomes. This is accompanied by a decrease in TET3 expression. Activation of TET3 by α-KG can improve ALP function and neural function to some extent. Silencing TET3 in neurons significantly inhibited the ALP function and increased apoptosis. Inhibition of miR-93-5p, which is elevated after SAH, promotes TET3 expression. This suggests that the downregulation of TET3 after SAH is, at least in part, due to elevated miR-93-5p. This study clarifies the key role of TET3 in the functional impairment of the ALP after SAH. The preliminary exploration revealed that miR-93-5p could lead to the downregulation of TET3, which could be a new target for neuroprotective therapy after SAH.

Analysis of different expression RNA binding protein genes in mouse microglia cell from the brains of mice 72 h after subarachnoid hemorrhage or sham operation.

BACKGROUND: The prognosis of brain injury caused by subarachnoid hemorrhage (SAH) is poor. Previous studies showed that abnormal function of RBPs might be involved in brain injury, neuroinflammation and further affect microglia homeostasis. However, no studies have systematically analyzed the genome-wide abnormal expression of RBPs genes in microglia during SAH. METHODS: RNA-seq data of microglia from the SAH mouse group (SAH) and control sham-operated mouse group (sham) were downloaded from the GEO database in GSE167957, including four samples from the sham group and four samples from the SAH group for subsequent analysis.Utilizing GO and KEGG functional enrichment analyses, we conducted a comprehensive study of differentially expressed genes (DEGs), alternative splicing patterns, and co-expression networks to gain deeper insights into the differential expression of RNA-binding proteins (RBPs) and differential alternative splicing events (ASEs) between the SAH (subarachnoid hemorrhage) and sham groups. This analysis aimed to elucidate the potential mechanisms underlying the aberrant expression of RBPs in microglia during brain injury caused by SAH. RESULTS: ASEs and co-expression analyses of differentially expressed RBPs and differential ASEs were carried out in microglia in terms of gene expression. GO and KEGG functional enrichment analysis showed that aberrantly expressed RBPs such as Mcm7, Mtdh, SRSF3, and Hnrnpa2b1 may affect and regulate downstream Csnk1d, Uckl1 and other protein phosphorylation-related genes by alterative splicing. CONCLUSION: RBPs were aberrantly expressed in microglia during the development of brain injury secondary to SAH, regulating alterative splicing of downstream genes and influencing the progression of SAH brain injury in this study. This implies that RBPs are important for the identification of new therapeutic targets for brain injury after SAH.

Sex differences in risk factor relationships with subarachnoid haemorrhage and intracranial aneurysms: A Mendelian Randomisation study.

Background: The prevalence of intracranial aneurysms (IAs) and incidence of aneurysmal subarachnoid haemorrhage (aSAH) is higher in women than in men. Although several cardiometabolic and lifestyle factors have been related to the risk of IAs or aSAH, it is unclear whether there are sex differences in causal relationships of these risk factors. Aims: The aim of this study was to determine sex differences in causal relationships between cardiometabolic and lifestyle factors and risk of aSAH and IA. Methods: We conducted a sex-specific two-sample Mendelian randomisation study using summary-level data from genome-wide association studies. We analysed low-density lipoprotein cholesterol, high-density lipoprotein cholesterol [HDL-C], triglycerides, non-HDL-C, total cholesterol, fasting glucose, systolic and diastolic blood pressure, smoking initiation, and alcohol use as exposures, and aSAH and IA (i.e., aSAH and unruptured IA combined) as outcomes. Results: We found statistically significant sex differences in the relationship between genetically proxied non-HDL-C and aSAH risk, with odds ratios (ORs) of 0.72 (95% confidence interval 0.58, 0.88) in women and 1.01 (0.77, 1.31) in men (P-value for sex difference 0.044). Moreover, genetic liability to smoking initiation was related to a statistically significantly higher risk of aSAH in men compared to women (P-value for sex difference 0.007) with ORs of 3.81 (1.93, 7.52) and 1.12 (0.63, 1.99), respectively, and to a statistically significantly higher IA risk in men compared to women (P-value for sex difference 0.036) with ORs of 3.58 (2.04, 6.27) and 1.61 (0.98, 2.64), respectively. In addition, higher genetically proxied systolic and diastolic blood pressure were related to a higher risk of aSAH and IA in both women and men. Conclusions: Higher genetically proxied non-HDL-C was related to a lower risk of aSAH in women compared to men. Moreover, genetic liability to smoking initiation was associated with a higher risk for aSAH and IA in men compared to women. These findings may help improve understanding of sex differences in the development of aSAH and IA.

Identification of key genes and immune infiltration in peripheral blood biomarker analysis of delayed cerebral ischemia: Valproic acid as a potential therapeutic drug.

BACKGROUND: Delayed cerebral ischemia (DCI) is a common and serious complication of subarachnoid hemorrhage (SAH). Its pathogenesis is not fully understood. Here, we developed a predictive model based on peripheral blood biomarkers and validated the model using several bioinformatic multi-analysis methods. METHODS: Six datasets were obtained from the GEO database. Characteristic genes were screened using weighted correlation network analysis (WGCNA) and differentially expressed genes. Three machine learning algorithms, elastic networks-LASSO, support vector machines (SVM-RFE) and random forests (RF), were also used to construct diagnostic prediction models for key genes. To further evaluate the performance and predictive value of the diagnostic models, nomogram model were constructed, and the clinical value of the models was assessed using Decision Curve Analysis (DCA), Area Under the Check Curve (AUC), Clinical Impact Curve (CIC), and validated in the mouse single-cell RNA-seq dataset. Mendelian randomization(MR) analysis explored the causal relationship between SAH and stroke, and the intermediate influencing factors. We validated this by retrospectively analyzing the qPCR levels of the most relevant genes in SAH and SAH-DCI patients. This experiment demonstrated a statistically significant difference between SAH and SAH-DCI and normal group controls. Finally, potential small molecule compounds interacting with the selected features were screened from the Comparative Toxicogenomics Database (CTD). RESULTS: The fGSEA results showed that activation of Toll-like receptor signaling and leukocyte transendothelial cell migration pathways were positively correlated with the DCI phenotype, whereas cytokine signaling pathways and natural killer cell-mediated cytotoxicity were negatively correlated. Consensus feature selection of DEG genes using WGCNA and three machine learning algorithms resulted in the identification of six genes (SPOCK2, TRRAP, CIB1, BCL11B, PDZD8 and LAT), which were used to predict DCI diagnosis with high accuracy. Three external datasets and the mouse single-cell dataset showed high accuracy of the diagnostic model, in addition to high performance and predictive value of the diagnostic model in DCA and CIC. MR analysis looked at stroke after SAH independent of SAH, but associated with multiple intermediate factors including Hypertensive diseases, Total triglycerides levels in medium HDL and Platelet count. qPCR confirmed that significant differences in DCI signature genes were observed between the SAH and SAH-DCI groups. Finally, valproic acid became a potential therapeutic agent for DCI based on the results of target prediction and molecular docking of the characterized genes. CONCLUSION: This diagnostic model can identify SAH patients at high risk for DCI and may provide potential mechanisms and therapeutic targets for DCI. Valproic acid may be an important future drug for the treatment of DCI.

Transcriptomics and metabolomics reveal hypothalamic metabolic characteristics and key genes after subarachnoid hemorrhage in rats.

Subarachnoid hemorrhage (SAH) is a serious hemorrhagic event with high mortality and morbidity. Multiple injurious events produced by SAH can lead to a series of pathophysiologic processes in the hypothalamus that can severely impact patients' life. These pathophysiologic processes usually result in physiologic derangements and dysfunction of the brain and multiple organs. This dysfunction involved multiple dimensions of the genome and metabolome. In our study, we induced the SAH model in rats to obtain hypothalamic tissue and serum. The samples were subsequently analyzed by transcriptomics and metabolomics. Next, the functional enrichment analysis of the differentially expressed genes and metabolites were performed by GO and KEGG pathway analysis. Through transcriptomic analysis of hypothalamus samples, 263 up-regulated differential genes, and 207 down-regulated differential genes were identified in SAH groups compared to Sham groups. In the KEGG pathway analysis, a large number of differential genes were found to be enriched in IL-17 signaling pathway, PI3K-Akt signaling pathway, and bile secretion. Liquid chromatography-mass spectrometry metabolomics technology was conducted on the serum of SAH rats and identified 11 up-regulated and 26 down-regulated metabolites in positive ion model, and 1 up-regulated and 10 down-regulated metabolites in negative ion model. KEGG pathways analysis showed that differentially expressed metabolites were mainly enriched in pathways of bile secretion and primary bile acid biosynthesis. We systematically depicted the neuro- and metabolism-related biomolecular changes occurring in the hypothalamus after SAH by performing transcriptomics and metabolomics studies. These biomolecular changes may provide new insights into hypothalamus-induced metabolic changes and gene expression after SAH.

BCAT1 alleviates early brain injury by inhibiting ferroptosis through PI3K/AKT/mTOR/GPX4 pathway after subarachnoid hemorrhage.

Regulation of the redox system by branched-chain amino acid transferase 1 (BCAT1) is of great significance in the occurrence and development of diseases, but the relationship between BCAT1 and subarachnoid hemorrhage (SAH) is still unknown. Ferroptosis, featured by iron-dependent lipid peroxidation accompanied by the depletion of glutathione peroxidase 4 (GPX4), has been implicated in the pathological process of early brain injury after subarachnoid hemorrhage. This study established SAH model by endovascular perforation and adding oxyhemoglobin (Hb) to HT22 cells and delved into the mechanism of BCAT1 in SAH-induced ferroptotic neuronal cell death. It was found that SAH-induced neuronal ferroptosis could be inhibited by BCAT1 overexpression (OE) in rats and HT22 cells, and BCAT1 OE alleviated neurological deficits and cognitive dysfunction in rats after SAH. In addition, the effect of BCAT1 could be reversed by the Ly294002, a specific inhibitor of the PI3K pathway. In summary, our present study indicated that BCAT1 OE alleviated early brain injury EBI after SAH by inhibiting neuron ferroptosis via activation of PI3K/AKT/mTOR pathway and the elevation of GPX4. These results suggested that BCAT1 was a promising therapeutic target for subarachnoid hemorrhage.

Nimodipine-associated standard dose reductions and neurologic outcomes after aneurysmal subarachnoid hemorrhage: the era of pharmacogenomics.

Nimodipine, an L-type cerebroselective calcium channel antagonist, is the only drug approved by the US Food and Drug Administration for the neuroprotection of patients with aneurysmal subarachnoid hemorrhage (aSAH). Four randomized, placebo-controlled trials of nimodipine demonstrated clinical improvement over placebo; however, these occurred before precision medicine with pharmacogenomics was readily available. The standard enteral dose of nimodipine recommended after aSAH is 60 mg every 4 h. However, up to 78% of patients with aSAH develop systemic arterial hypotension after taking the drug at the recommended dose, which could theoretically limit its neuroprotective role and worsen cerebral perfusion pressure and cerebral blood flow, particularly when concomitant vasospasm is present. We investigated the association between nimodipine dose changes and clinical outcomes in a consecutive series of 150 patients (mean age, 56 years; 70.7% women) with acute aSAH. We describe the pharmacogenomic relationship of nimodipine dose reduction with clinical outcomes. These results have major implications for future individualized dosing of nimodipine in the era of precision medicine.

Machine learning and deep learning to identifying subarachnoid haemorrhage macrophage-associated biomarkers by bulk and single-cell sequencing.

We investigated subarachnoid haemorrhage (SAH) macrophage subpopulations and identified relevant key genes for improving diagnostic and therapeutic strategies. SAH rat models were established, and brain tissue samples underwent single-cell transcriptome sequencing and bulk RNA-seq. Using single-cell data, distinct macrophage subpopulations, including a unique SAH subset, were identified. The hdWGCNA method revealed 160 key macrophage-related genes. Univariate analysis and lasso regression selected 10 genes for constructing a diagnostic model. Machine learning algorithms facilitated model development. Cellular infiltration was assessed using the MCPcounter algorithm, and a heatmap integrated cell abundance and gene expression. A 3 × 3 convolutional neural network created an additional diagnostic model, while molecular docking identified potential drugs. The diagnostic model based on the 10 selected genes achieved excellent performance, with an AUC of 1 in both training and validation datasets. The heatmap, combining cell abundance and gene expression, provided insights into SAH cellular composition. The convolutional neural network model exhibited a sensitivity and specificity of 1 in both datasets. Additionally, CD14, GPNMB, SPP1 and PRDX5 were specifically expressed in SAH-associated macrophages, highlighting its potential as a therapeutic target. Network pharmacology analysis identified some targeting drugs for SAH treatment. Our study characterised SAH macrophage subpopulations and identified key associated genes. We developed a robust diagnostic model and recognised CD14, GPNMB, SPP1 and PRDX5 as potential therapeutic targets. Further experiments and clinical investigations are needed to validate these findings and explore the clinical implications of targets in SAH treatment.

The association between hematologic traits and aneurysm-related subarachnoid hemorrhage: a two-sample mendelian randomization study.

Several hematologic traits have been suggested to potentially contribute to the formation and rupture of intracranial aneurysms (IA). The purpose of this study is to explore the causal association between hematologic traits and the risk of IA. To explore the causal association between hematologic traits and the risk of IA, we employed two-sample Mendelian randomization (MR) analysis. Two independent summary-level GWAS data were used for preliminary and replicated MR analyses. The inverse variance weighted (IVW) method was employed as the primary method in the MR analyses. The stabilities of the results were further confirmed by a meta-analysis. In the preliminary MR analysis, hematocrit, hemoglobin concentration (p = 0.0047), basophil count (p = 0.0219) had a suggestive inverse causal relationship with the risk of aneurysm-associated subarachnoid hemorrhage (aSAH). The monocyte percentage of white cells (p = 0.00956) was suggestively positively causally correlated with the risk of aSAH. In the replicated MR analysis, only the monocyte percentage of white cells (p = 0.00297) remained consistent with the MR results in the preliminary analysis. The hematocrit, hemoglobin concentration, and basophil count no longer showed significant causal relationship (p > 0.05). Meta-analysis results further confirmed that only the MR result of monocyte percentage of white cells reached significance in the random effect model and fixed effect model. None of the 25 hematologic traits was causally associated with the risk of unruptured intracranial aneurysms (uIA). This study revealed a suggestive positive association between the monocyte percentage of white cells and the risk of aSAH. This finding contributes to a better understanding that monocytes/macrophages could participate in the risk of aSAH.

Causal association between circulating inflammatory cytokines and intracranial aneurysm and subarachnoid hemorrhage.

BACKGROUND AND PURPOSE: The causal association between inflammatory cytokines and the development of intracranial aneurysm (IA), unruptured IA (uIA) and subarachnoid hemorrhage (SAH) lacks clarity. METHODS: The summary-level datasets for inflammatory cytokines were extracted from a genome-wide association study of the Finnish Cardiovascular Risk in Young Adults Study and the FINRISK survey. The summary statistics datasets related to IA, uIA and SAH were obtained from the genome-wide association study meta-analysis of the International Stroke Genetics Consortium and FinnGen Consortium. The primary method employed for analysis was inverse variance weighting (false discovery rate), supplemented by sensitivity analyses to address pleiotropy and enhance robustness. RESULTS: In the International Stroke Genetics Consortium, 10, six and eight inflammatory cytokines exhibited a causal association with IA, uIA and SAH, respectively (false discovery rate, p < 0.05). In FinnGen datasets, macrophage Inflammatory Protein-1 Alpha (MIP_1A), MIP_1A and interferon γ-induced protein 10 (IP_10) were verified for IA, uIA and SAH, respectively. In the reverse Mendelian randomization analysis, the common cytokines altered by uIA and SAH were vascular endothelial growth factor (VEGF), MIP_1A, IL_9, IL_10 and IL_17, respectively. The meta-analysis results show that MIP_1A and IP_10 could be associated with the decreased risk of IA, and MIP_1A and IP_10 were associated with the decreased risk of uIA and SAH, respectively. Notably, the levels of VEGF, MIP_1A, IL_9, IL_10 and TNF_A were increased with uIA. Comprehensive heterogeneity and pleiotropy analyses confirmed the robustness of these results. CONCLUSION: Our study unveils a bidirectional association between inflammatory cytokines and IA, uIA and SAH. Further investigations are essential to validate their relationship and elucidate the underlying mechanisms.

Molecular Basis of Cerebral Vasospasm: What Can We Learn from Transcriptome and Temporal Gene Expression Profiling in Intracranial Aneurysm?

Cerebral vasospasm (CV) is a significant complication following aneurysmal subarachnoid hemorrhage (aSAH), and lacks a comprehensive molecular understanding. Given the temporal trajectory of intracranial aneurysm (IA) formation, its rupture, and development of CV, altered gene expression might be a molecular substrate that runs through these clinical events, influencing both disease inception and progression. Utilizing RNA-Seq, we analyzed tissue samples from ruptured IAs with and without vasospasm to identify the dysregulated genes. In addition, temporal gene expression analysis was conducted. We identified seven dysregulated genes in patients with ruptured IA with vasospasm when compared with those without vasospasm. We found 192 common genes when the samples of each clinical subset of patients with IA, that is, unruptured aneurysm, ruptured aneurysm without vasospasm, and ruptured aneurysm with vasospasm, were compared with control samples. Among these common genes, TNFSF13B, PLAUR, OSM, and LAMB3 displayed temporal expression (progressive increase) with the pathological progression of disease that is formation of aneurysm, its rupture, and consequently the development of vasospasm. We validated the temporal gene expression pattern of OSM at both the transcript and protein levels and OSM emerges as a crucial gene implicated in the pathological progression of disease. In addition, RSAD2 and ATP1A2 appear to be pivotal genes for CV development. To the best of our knowledge, this is the first study to compare the transcriptome of aneurysmal tissue samples of aSAH patients with and without CV. The findings collectively provide new insights on the molecular basis of IA and CV and new leads for translational research.

Differential DNA methylation associated with delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage: a systematic review.

Recent studies suggest that differential DNA methylation could play a role in the mechanism of cerebral vasospasm (CVS) and delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH). Considering the significance of this matter and a lack of effective prophylaxis against DCI, we aim to summarize the current state of knowledge regarding their associations with DNA methylation and identify the gaps for a future trial. PubMed MEDLINE, Scopus, and Web of Science were searched by two authors in three waves for relevant DNA methylation association studies in DCI after aSAH. PRISMA checklist was followed for a systematic structure. STROBE statement was used to assess the quality and risk of bias within studies. This research was funded by the National Science Centre, Poland (grant number 2021/41/N/NZ2/00844). Of 70 records, 7 peer-reviewed articles met the eligibility criteria. Five studies used a candidate gene approach, three were epigenome-wide association studies (EWAS), one utilized bioinformatics of the previous EWAS, with two studies using more than one approach. Methylation status of four cytosine-guanine dinucleotides (CpGs) related to four distinct genes (ITPR3, HAMP, INSR, CDHR5) have been found significantly or suggestively associated with DCI after aSAH. Analysis of epigenetic clocks yielded significant association of lower age acceleration with radiological CVS but not with DCI. Hub genes for hypermethylation (VHL, KIF3A, KIFAP3, RACGAP1, OPRM1) and hypomethylation (ALB, IL5) in DCI have been indicated through bioinformatics analysis. As none of the CpGs overlapped across the studies, meta-analysis was not applicable. The identified methylation sites might potentially serve as a biomarker for early diagnosis of DCI after aSAH in future. However, a lack of overlapping results prompts the need for large-scale multicenter studies. Challenges and prospects are discussed.

The influence of epigenetic biological age on key complications and outcomes in aneurysmal subarachnoid haemorrhage.

BACKGROUND: We aimed to investigate the association between DNA-methylation biological age (B-age) calculated as age acceleration (ageAcc) and key aneurysmal subarachnoid haemorrhage (aSAH) complications such as vasospasm, delayed cerebral ischaemia (DCI), poor outcome, and mortality. METHODS: We conducted a prospective study involving 277 patients with aSAH. B-age was determined in whole blood samples using five epigenetic clocks: Hannum's, Horvath's, Levine's and both versions of Zhang's clocks. Age acceleration was calculated as the residual obtained from regressing out the effect of C-age on the mismatch between C-age and B-age. We then tested the association between ageAcc and vasospasm, DCI and 12-month poor outcome (mRS 3-5) and mortality using linear regression models adjusted for confounders. RESULTS: Average C-age was 55.0 years, with 66.8% being female. Vasospasm occurred in 143 cases (51.6%), DCI in 70 (25.3%) and poor outcomes in 99 (35.7%), with a mortality rate of 20.6%. Lower ageAcc was linked to vasospasm in Horvath's and Levine's clocks, whereas increased ageAcc was associated with 12-month mortality in Hannum's clock. No significant differences in ageAcc were found for DCI or poor outcome at 12 months with other clocks. CONCLUSIONS: Our study indicates that B-age is independently associated with vasospasm and 12-month mortality in patients with aSAH. These findings underscore the potential role of epigenetics in understanding the pathophysiology of aSAH-related complications and outcomes.

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.

TREM2 Alleviates Subarachnoid Hemorrhage-Induced Brain Injury through Attenuating Neuroinflammation and Programmed Cell Death in Vivo and in Vitro.

BACKGROUND: Apoptosis and pyroptosis are two types of programmed cell death related to the neuroinflammatory reaction after subarachnoid hemorrhage (SAH). Research indicates that triggering receptor expressed on myeloid cells 2 (TREM2) can regulate the SAH-induced inflammatory response. However, whether TREM2 regulates programmed cell death (apoptosis and pyroptosis) remains to be clarified. The purpose of the present study was to investigate the effects of TREM2 on cell death in SAH. METHODS: SAH was induced in adult male C57BL/6J mice by endovascular perforation. An in-vitro cellular model of SAH was established by treating cocultured BV2 microglia and HT22 neuronal cells with oxyhemoglobin. TREM2 overexpression or knockdown was carried out by intraventricular lentivirus injection at 7 d before SAH induction in mice or lentiviral transfection, respectively. Neurobehavioral tests as well as western blot, reverse transcription-quantitative polymerase chain reaction (RT-qPCR), immunofluorescence, Evans blue (EB) staining, Nissl staining, and flow cytometry assays were performed to investigate the neuroprotective role of TREM2 after SAH. RESULTS: After SAH, the TREM2 mRNA and protein levels were elevated in SAH mice, exhibiting a peak at 72 h. TREM2 overexpression improved the SAH-induced neurological deficits in mice, while TREM2 knockdown worsened them. In the brains of mice with TREM2 overexpression, less neuronal death and more neuronal survival were detected at 72 h post SAH. Meanwhile, TREM2 overexpression showed an inhibitory effect on microglial activation, neutrophil infiltration, and the expression of cell death marker proteins. Consistent results were obtained in vitro. CONCLUSIONS: Our research indicates the important role of TREM2 on cell death after SAH, suggesting that targeting TREM2 might be an effective approach for treating SAH.

MicroRNA-124 conducts neuroprotective effect via inhibiting AK4/ATF3 after subarachnoid hemorrhage.

Spontaneous subarachnoid hemorrhage (SAH) accounts for approximately 5% of all cases of stroke. SAH is correlated with elevated rates of mortality and disability. Despite significant advancements in comprehending the pathogenesis and surgical management, efficacious clinical interventions remain restricted, and the prognosis is yet to be enhanced. MicroRNAs play a crucial role in various pathological processes in organisms. Revealing these regulatory processes is conducive to the development of new treatment methods. MicroRNA-124 is highly expressed in the nervous system and has significant research value for SAH. This study aims to explore the role of miR-124 in the early post-SAH period on neural function and verify whether it is involved in the pathological and physiological processes of SAH. In this study, we used methods such as comparing the expression levels of miR-124 in cerebrospinal fluid, establishing a rat SAH model, and a mouse embryonic primary neuron hemoglobin stimulation model to verify the downstream proteins of miR-124 in SAH. Through transfection techniques, we adjusted the expression of this small RNA in Vitro and in Vivo models using miR-124 inhibitor and mimic in the primary neuron hemoglobin stimulation model and rat SAH model, and observed the phenotype. Finally, by consulting the literature and verifying in Vivo and in Vitro methods, AK4 and downstream molecule ATF3 were identified as downstream targets of miR-124.