Pathogenesis Of Intracranial Aneurysms Research Articles

Single-cell analysis reveals the implication of vascular endothelial cell-intrinsic ANGPT2 in human intracranial aneurysm.

While previous single-cell RNA sequencing (scRNA-seq) studies have attempted to dissect intracranial aneurysm (IA), the primary molecular mechanism for IA pathogenesis remains unknown. Here, we uncovered the alterations of cellular compositions, especially the transcriptome changes of vascular endothelial cells (ECs), in human IA. We performed scRNA-seq to compare the cell atlas of sporadic IA and the control artery. The transcriptomes of 43,462 cells were profiled for further analysis. In general, IA had increased immune cells (T/NK cells, B cells, myeloid cells, mast cells, neutrophils) and fewer vascular cells (ECs, vascular smooth muscle cells and fibroblasts). Based on the obtained high-quantity and high-quality EC data, we found genes associated with angiogenesis in ECs from IA patients. By EC-specific expression of candidate genes in vivo, we observed the involvement of angpt2a in causing cerebral vascular abnormality. Furthermore, an IA zebrafish model mimicking the main features of human IA was generated through targeting pdgfrb gene, and knockdown of angpt2a alleviated the vascular dilation in the IA zebrafish model. By performing a landscape view of the single-cell transcriptomes of IA and the control artery, we contribute to a deeper understanding of the cellular composition and the molecular changes of ECs in IA. The implication of angiogenic regulator ANGPT2 in IA formation and progression, provides a novel potential therapeutical target for IA interventions.

Phoenixin-14 maintains the contractile type of vascular smooth muscle cells in cerebral aneurysms rats.

The rupture of intracranial aneurysm (IA) is the primary reason contributing to the occurrence of life-threatening subarachnoid hemorrhages. The oxidative stress-induced phenotypic transformation from the contractile phenotype to the synthetic phenotype of vascular smooth muscle cells (VSMCs) plays a pivotal role in IA formation and rupture. Our study aimed to figure out the role of phoenixin-14 in VSMC phenotypic switching during the pathogenesis of IA by using both cellular and animal models. Primary rat VSMCs were isolated from the Willis circle of male Sprague-Dawley rats. VSMCs were stimulated by hydrogen peroxide (H2O2) to establish a cell oxidative damage model. After pretreatment with phoenixin-14 and exposure to H2O2, VSMC viability, migration, and invasion were examined through cell counting kit-8 (CCK-8), wound healing, and Transwell assays. Intracellular reactive oxygen species (ROS) production in VSMCs was evaluated by using 2',7'-Dichlorofluorescin diacetate (DCFH-DA) fluorescence probes and flow cytometry. Rat IA models were established by ligation of the left common carotid arteries and posterior branches of both renal arteries. The histopathological changes of rat intracranial blood vessels were observed through hematoxylin and eosin staining. The levels of contractile phenotype markers (alpha-smooth muscle actin [α-SMA] and smooth muscle 22 alpha [SM22α]) in VSMCs and rat arterial rings were determined through real-time quantitative polymerase chain reaction (RT-qPCR) and western blot analysis. Our results showed that H2O2 stimulated the production of intracellular ROS and induced oxidative stress in VSMCs, while phoenixin-14 pretreatment attenuated intracellular ROS levels in H2O2-exposed VSMCs. H2O2 exposure promoted VSMC migration and invasion, which, however, was reversed by phoenixin-14 pretreatment. Besides, phoenixin-14 administration inhibited IA formation and rupture in rat models. The decrease in α-SMA and SM22α levels in H2O2-exposed VSMCs and IA rat models was antagonized by phoenixin-14. Collectively, phoenixin-14 ameliorates the progression of IA through preventing the loss of the contractile phenotype of VSMCs.

Identification of immune-inflammation targets for intracranial aneurysms: A multiomics and epigenome-wide study integrating summary-data-based mendelian randomization, single-cell-type expression analysis, and DNA methylation regulation.

Dysfunction of the immune system and inflammation plays a vital role in developing intracranial aneurysms (IAs). However, the progress of genetic pathophysiology is complicated and not entirely elaborated. This study aimed to explore the genetic associations of immune- and inflammation-related genes (IIRGs) with IAs and their subtypes using Mendelian randomization, colocalization test, and integrated multiomics functional analysis. We conducted a summary-data-based Mendelian randomization (SMR) analysis using data from several genome-wide association studies of gene expression (31,684 European individuals) and protein quantitative trait loci (35,559 Icelanders), as well as information on IAs and their subtypes from The International Stroke Genetics Consortium (IGSC) for discovery phase and the FinnGen study for replication. This analysis aimed to determine the causal relationship between IIRGs and the risk of IAs and their subtypes. Further functional analyses, including DNA methylation regulation (1980, European individuals), single-cell-type expression analysis, and protein-protein interaction, were conducted to detect the specific cell type with enriched expression and discover potential drug targets. After integrating multi-omics evidence from expression quantitative trait loci (eQTL)and protein quantitative trait loci(pQTL), we found that tier 1: RELT [odds ratio (OR): 0.14, 95% confidence interval (CI): 0.04-0.50], TNFSF12 (OR: 1.24, 95% CI: 1.24-1.43), tier 3:ICAM5 (OR: 0.89, 95% CI: 0.82-0.96), and ERAP2 (OR: 1.07, 95% CI: 1.02-1.12) were associated with the risk of IAs; tier 3: RELT (OR: 0.11, 95% CI: 0.02-0.54), ERAP2 (OR: 1.08, 95% CI: 1.02-1.13), and TNFSF12 (OR: 1.24, 95% CI: 1.05-1.47) were associated with the risk of aneurysmal subarachnoid hemorrhage (aSAH); and tier 1:RELT (OR: 0.04, 95% CI: 0.01-0.30) was associated with the risk of unruptured intracranial aneurysms (uIAs). Further functional analyses showed that RELT was regulated by cg06382664 and cg18850434 and ICAM5 was regulated by cg04295144 in IAs; RELT was regulated by cg06382664, cg08770935, cg16533363, and cg18850434 in aSAH; and RELT was regulated by cg06382664 and cg21810604 in uIAs. In addition, we found that H6PD (OR: 1.13, 95% CI: 1.01-1.28), NT5M (OR: 1.91, 95% CI: 1.21-3.01), and NPTXR (OR: 1.13, 95% CI: 1.01-1.26) were associated with IAs; NT5M (OR: 2.13, 95% CI: 1.23-3.66) was associated aSAH; and AP4M1 (OR: 0.06, 95% CI: 0.01-0.42) and STX7 (OR: 3.97, 95% CI: 1.41-11.18) were related to uIAs. STX7 and TNFSF12 were mainly enriched in microglial cells, whereas H6PD, STX7, and TNFSF12 were mainly enriched in astrocytes. After integrating multi-omics evidence, we eventually identified IIRGs: RELT, TNFSF12, ICAM5 and ERAP2 were the novel therapy targets for IAs. These new results confirmed a vital role of immune and inflammation in the etiology of IAs, contributing to enhance our understanding of the immune and inflammatory mechanisms in the pathogenesis of IAs and revealing the complex genetic causality of IAs.

Integrated analysis of single-cell sequencing and machine learning identifies a signature based on monocyte/macrophage hub genes to analyze the intracranial aneurysm associated immune microenvironment.

Monocytes are pivotal immune cells in eliciting specific immune responses and can exert a significant impact on the progression, prognosis, and immunotherapy of intracranial aneurysms (IAs). The objective of this study was to identify monocyte/macrophage (Mo/MΦ)-associated gene signatures to elucidate their correlation with the pathogenesis and immune microenvironment of IAs, thereby offering potential avenues for targeted therapy against IAs. Single-cell RNA-sequencing (scRNA-seq) data of IAs were acquired from the Gene Expression Synthesis (GEO) database. The significant infiltration of monocyte subsets in the parietal tissue of IAs was identified using single-cell RNA sequencing and high-dimensional weighted gene co-expression network analysis (hdWGCNA). The integration of six machine learning algorithms identified four crucial genes linked to these Mo/MΦ. Subsequently, we developed a multilayer perceptron (MLP) neural model for the diagnosis of IAs (independent external test AUC=1.0, sensitivity =100%, specificity =100%). Furthermore, we employed the CIBERSORT method and MCP counter to establish the correlation between monocyte characteristics and immune cell infiltration as well as patient heterogeneity. Our findings offer valuable insights into the molecular characterization of monocyte infiltration in IAs, which plays a pivotal role in shaping the immune microenvironment of IAs. Recognizing this characterization is crucial for comprehending the limitations associated with targeted therapies for IAs. Ultimately, the results were verified by real-time fluorescence quantitative PCR and Immunohistochemistry.

Endothelial Progenitor Cells: A Review of Molecular Mechanisms in the Pathogenesis and Endovascular Treatment of Intracranial Aneurysms.

This comprehensive review explores the multifaceted role of endothelial progenitor cells (EPCs) in vascular diseases, focusing on their involvement in the pathogenesis and their contributions to enhancing the efficacy of endovascular treatments for intracranial aneurysms (IAs). Initially discovered as CD34+ bone marrow-derived cells implicated in angiogenesis, EPCs have been linked to vascular repair, vasculogenesis, and angiogenic microenvironments. The origin and differentiation of EPCs have been subject to debate, challenging the conventional notion of bone marrow origin. Quantification methods, including CD34+ , CD133+ , and various assays, reveal the influence of factors, like age, gender, and comorbidities on EPC levels. Cellular mechanisms highlight the interplay between bone marrow and angiogenic microenvironments, involving growth factors, matrix metalloproteinases, and signaling pathways, such as phosphatidylinositol-3-kinase (PI3K) and mitogen-activated protein kinase (MAPK). In the context of the pathogenesis of IAs, EPCs play a role in maintaining vascular integrity by replacing injured and dysfunctional endothelial cells. Recent research has also suggested the therapeutic potential of EPCs after coil embolization and flow diversion, and this has led the development of device surface modifications aimed to enhance endothelialization. The comprehensive insights underscore the importance of further research on EPCs as both therapeutic targets and biomarkers in IAs.

Circ_0008571 modulates the phenotype of vascular smooth muscle cells by targeting miR-145-5p in intracranial aneurysms

BackgroundThe dysfunction of human vascular smooth cells (hVSMCs) is significantly connected to the development of intracranial aneurysms (IAs). By suppressing the activity of microRNAs (miRNAs), circular RNAs (circRNAs) participate in IA pathogenesis. Nevertheless, the role of hsa_circ_0008571 in IAs remains unclear. MethodscircRNA sequencing was used to identify circRNAs from human IA tissues. To determine the function of circ_0008571, Transwell, wound healing, and cell proliferation assays were conducted. To identify the target of circ_0008571, the analyses of CircInteractome and TargetScan, as well as the luciferase assay were carried out. Furthermore, circ_0008571 knockdown and over-expression were performed to investigate its functions in IA development and the underlying molecular mechanisms. ResultsBoth hsa_circ_0008571 and Integrin beta 8 (ITGB8) were downregulated, while miR-145-5p transcription was elevated in the aneurysm wall of IAs patients compared to superficial temporal artery tissues. In vitro, cell migration and growth were dramatically suppressed after hsa_circ_0008571 overexpression. Mechanistically, has_circ_0008571 could suppress miR-145-5p activity by direct sponging. Moreover, we found that ITGB8 expression and the activation of the TGF-β-mediated signaling pathway were significantly enhanced. ConclusionThe hsa_circ_0008571-miR-145-5p-ITGB8 axis plays an essential role in IA progression.

Bioinformatics analysis revealed the potential crosstalk genes and molecular mechanisms between intracranial aneurysms and periodontitis

ObjectivesThe risk of intracranial aneurysms (IAs) development and rupture is significantly higher in patients with periodontitis (PD), suggesting an association between the two. However, the specific mechanisms of association between these two diseases have not been fully investigated.Materials and methodsIn this study, we downloaded IAs and PD data from the Gene Expression Omnibus. Differentially expressed genes (DEGs) were identified, and functional enrichment analysis was performed. The protein-protein interaction (PPI) network and weighted gene co-expression network analysis (WGCNA) was performed to identified key modules and key crosstalk genes. In addition, the immune cell landscape was assessed and the correlation of key crosstalk genes with each immune cell was calculated. Finally, transcription factors (TFs) regulating key crosstalk genes were explored.Results127 overlapping DEGs were identified and functional enrichment analysis highlighted the important role of immune reflection in the pathogenesis of IAs and PD. We identified ITGAX and COL4A2 as key crosstalk genes. In addition, the expression of multiple immune cells was significantly elevated in PDs and IAs compared to controls, and both key crosstalk genes were significantly negatively associated with Macrophages M2. Finally, GATA2 was identified as a potential key transcription factor (TF), which regulates two key crosstalk gene.ConclusionsThe present study identifies key crosstalk genes and TF in PD and IAs, providing new insights for further study of the co-pathogenesis of PD and IAs from an immune and inflammatory perspective. Also, this is the first study to report the above findings.

Identification of differentially expressed autophagy-related genes in cases of intracranial aneurysm: Bioinformatics analysis

ObjectiveRecent research indicates that autophagy is essential for the rupture of intracranial aneurysm (IA). This study aimed to examine and validate potential autophagy-related genes (ARGs) in cases of IA using bioinformatics analysis. MethodsTwo expression profiles (GSE54083 and GSE75436) were obtained from the Gene Expression Omnibus database. Differentially expressed ARGs (DEARGs) in cases of IA were screened using GSE75436, and enrichment analysis and Protein–Protein Interaction (PPI) networks were used to identify the hub genes and related pathways. Furthermore, a novel predictive diagnostic signature for IA based on the hub genes was constructed. The area under the Receiver Operating Characteristic curve (AUC) was used to evaluate the signature performance in GSE75436. ResultsIn total, 75 co-expressed DEARGs were identified in the GSE75436 and GSE54083 dataset (28 upregulated and 47 downregulated genes). Enrichment analysis of DEARGs revealed several enriched terms associated with proteoglycans in cancer and human immunodeficiency virus 1 infection. PPI analysis revealed interactions between these genes. Hub DEARGs included insulin-like growth factor 1, clusters of differentiation 4, cysteine-aspartic acid protease 8, Bcl-2-like protein 11, mouse double mutant 2 homolog, toll-like receptor 4, growth factor receptor-bound protein 2, Jun proto-oncogene, AP-1 transcription factor subunit, hypoxia inducible factor 1 alpha, and erythroblastic oncogene B-2. Notably, the signature showed good performance in distinguishing IA (AUC = 0.87). The sig calibration curves showed good calibration. ConclusionBioinformatic analysis identified 75 potential DEARGs in cases of IA. This study revealed that IA is affected by autophagy, which could explain the pathogenesis of IA and aid in its diagnosis and treatment. However, future research with experimental validation is necessary to identify potential DEARGs in cases of IA.

Immunological alterations in intracranial aneurysm: a prospective study on selected biomarker profiles in blood collected during endovascular neurointervention.

Previous studies showed that the concentrations of selected chemokines are locally elevated in samples collected from the lumen of intracranial aneurysms (IA). Our objective was to determine whether the observed differences in analyte concentrations were influenced by the origin of the blood samples (i.e. cerebral versus peripheral), thus providing insight into the localised nature of these alterations and their significance in IA pathogenesis. This prospective study included 24 patients with IA who underwent endovascular embolisation. Concentrations of selected analytes were analysed in blood samples from the IA lumen, feeding artery, and aorta. The analytes included MPO, Lipocalin-2/NGAL, sICAM-1, sVCAM-1, and serum amyloid A. Higher median plasma concentrations of MPO, lipocalin-2/NGAL, sVCAM-1, and SAA were found in samples obtained from the IA lumen and the feeding artery compared to the aorta. The concentration of sICAM-1 was significantly higher in the IA compared to the aorta, but did not differ between the proximal artery and the aorta. No significant differences in any analyte concentration were observed between the IA and the proximal artery. These findings suggest that the IA and the proximal vessel share similarities in the local immunological environment, which is different from that observed in the aorta. Further studies are needed to fully understand and elucidate these observations.

The Role of Epigenetics in Brain Aneurysm and Subarachnoid Hemorrhage: A Comprehensive Review.

This comprehensive review explores the emerging field of epigenetics in intracranial aneurysm (IA) and aneurysmal subarachnoid hemorrhage (aSAH). Despite recent advancements, the high mortality of aSAH needs an understanding of its underlying pathophysiology, where epigenetics plays a crucial role. This review synthesizes the current knowledge, focusing on three primary epigenetic mechanisms: DNA methylation, non-coding RNA (ncRNA), and histone modification in IA and aSAH. While DNA methylation studies are relatively limited, they suggest a significant role in the pathogenesis and prognosis of IA and aSAH, highlighting differentially methylated positions in genes presumably involved in these pathologies. However, methodological limitations, including small sample sizes and a lack of diverse population studies, temper these results. The role of ncRNAs, particularly miRNAs, has been more extensively studied, but there are still few studies focused on histone modifications. Despite methodological challenges and inconsistent findings, these studies underscore the involvement of miRNAs in key pathophysiological processes, including vascular smooth muscle regulation and the inflammatory response. This review emphasizes methodological challenges in epigenetic research, advocating for large-scale epigenome-wide association studies integrating genetic and environmental factors, along with longitudinal studies. Such research could unravel the complex mechanisms behind IA and aSAH, guiding the development of targeted therapeutic approaches.

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.

Effects of KLF11 on Vascular Smooth Muscle Cells and its Underlying Mechanisms in Intracranial Aneurysm.

Vascular smooth muscle cells (VSMCs) affect the phenotypic changes in intracranial aneurysm (IA). They exhibit enhanced dissociation and migration and play a key role in IA pathogenesis. KLF transcription factor 11 (KLF11), a member of the KLF family, significantly affects the cancer cell proliferation, differentiation, and apoptosis. However, its expression, biological functions, and latent action mechanisms in IA remain unclear. This study aimed to analyze the effects of KLF11 on H2O2-induced human brain VSMCs (HBVSMCs) in IA. We determined the mRNA levels of KLF11 in 15 paired arterial wall tissues of patients with IA and healthy volunteers. HBVSMCs were stimulated with H2O2 for 6h to establish an IA model in vitro. Cell viability, apoptosis, and inflammatory cytokine (interleukin [IL-1β, tumor necrosis factor-α, and IL-6) levels were assessed using the 3-(4,5-dimethylthiazol-2-yl)-2-5-diphenyltetrazolium bromide, flow cytometry, and enzyme-linked immunosorbent assays, respectively. KLF11 expression was determined via quantitative reverse transcription-polymerase chain reaction, western blotting, and immunofluorescence analyses. Furthermore, p-p38, p38, cleaved-caspase 3, and caspase 3 levels were determined via western blotting. KLF11 levels were downregulated in the arterial wall tissues of patients with IA than in those of the control group. KLF11 upregulation by KLF11-plasmid promoted the cell viability, reduced apoptosis, decreased cleaved-caspase 3 expression, and inhibited the secretion of inflammatory factors in H2O2-induced HBVSMCs. KLF11-plasmid remarkably reduced p-p38 expression and p-p38/p-38 ratio; however, these effects were reversed by P79350 treatment. Overall, KLF11 upregulation improved the HBVSMC functions and exerted protective effects against IA, suggesting its potential for IA treatment.

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

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. 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. 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. 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.

Exosomal lncRNA DUXAP8 affecting CHPF2 in the pathogenesis of intracranial aneurysms

ObjectiveThis study endeavored to explore the relationship between exosome-derived lncRNA Double Homeobox A Pseudogene 8 (DUXAP8) and Chondroitin Polymerizing Factor 2 (CHPF2), and their roles in the pathogenesis of intracranial aneurysm (IA). MethodsThe shared targeted molecules (DUXAP8 and CHPF2) were detected via GSE122897 and GSE75436 datasets. A total of 312 patients with IAs were incorporated into this study. Exosomes were isolated from serum samples, and their identity was confirmed using Western blotting for exosomal markers (CD9, CD63 and ALIX). Inflammatory responses in IA tissues were evaluated using Hematoxylin-Eosin staining. CHPF2 protein concentration and the expression levels of DUXAP8 and CHPF2 mRNA in exosomal samples were assessed using Immunochemistry (IHC), Western Blotting, and qRT-PCR, respectively. Cell-based assays involving Human Umbilical Vein Endothelial Cells (HuvECs), including transfection with exosomal DUXAP8, Western Blotting, qRT-PCR, and Cell Counting Kit-8, were conducted. Receiver Operating Characteristic (ROC) curves were derived using SPSS. ResultsDUXAP8 level affects the level of CHPF2. DUXAP8 expression within exosomes was associated with increased CD9, CD63, ALIX and CHPF2 levels during IA development and inflammatory stress. In HuvECs, transfection with exosomes carrying DUXAP8 siRNA resulted in reduced CHPF2 expression, whereas DUXAP8 mimic increased CHPF2 concentrations. The Area Under the ROC Curve (AUC) for exosomal DUXAP8 expression and CHPF2 levels, and aneurysm size was 0.768 (95% CI, 0.613 to 0.924), 0.937 (95% CI, 0.853 to 1.000), and 0.943 (95% CI, 0.860, 1.000), respectively. ConclusionExosome-derived DUXAP8 promotes IA progression by affecting CHPF2 expression.

Decreased PDLIM1 expression in endothelial cells contributes to the development of intracranial aneurysm.

Intracranial aneurysm (IA) is a common vascular enlargement that occurs in the wall of cerebral vessels and frequently leads to fatal subarachnoid hemorrhage. PDZ and LIM domain protein 1 (PDLIM1) is a cytoskeletal protein that functions as a platform for multiple protein complex formation. However, whether PDLIM is involved in the pathogenesis of IA remains poorly understood. Loss-of-function and gain-of-function strategies were employed to determine the in vitro roles of PDLIM1 in vascular endothelial cells (VECs). A rat model of IA was generated to study the role of PDLIM1 in vivo. Gene expression profiling, Western blotting, and dual luciferase reporter assays were performed to uncover the underlying cellular mechanism. Clinical IA samples were used to determine the expression of PDLIM1 and its downstream signaling molecules. PDLIM1 expression was reduced in the endothelial cells of IA and was regulated by Yes-associated protein 1 (YAP1). Genetic silencing of PDLIM1 inhibited the viability, migratory ability, and tube formation ability of VECs. Opposite results were obtained by ectopic expression of PDLIM1. Additionally, PDLIM1 overexpression mitigated IA in vivo. Mechanistic investigations revealed that PDLIM1 promoted the transcriptional activity of β-catenin and induced the expression of v-myc myelocytomatosis viral oncogene homolog (MYC) and cyclin D1 (CCND1). In clinical settings, reduced expression of PDLIM1 and β-catenin downstream target genes was observed in human IA samples. Our study indicates that YAP1-dependent expression of PDLIM1 can inhibit IA development by modulating the activity of the Wnt/β-catenin signaling pathway and that PDLIM1 deficiency in VECs may represent a potential marker of aggressive disease.

Current understanding of macrophages in intracranial aneurysm: relevant etiological manifestations, signaling modulation and therapeutic strategies.

Macrophages activation and inflammatory response play crucial roles in intracranial aneurysm (IA) formation and progression. The outcome of ruptured IA is considerably poor, and the mechanisms that trigger IA progression and rupture remain to be clarified, thereby developing effective therapy to prevent subarachnoid hemorrhage (SAH) become difficult. Recently, climbing evidences have been expanding our understanding of the macrophages relevant IA pathogenesis, such as immune cells population, inflammatory activation, intra-/inter-cellular signaling transductions and drug administration responses. Crosstalk between macrophages disorder, inflammation and cellular signaling transduction aggravates the devastating consequences of IA. Illustrating the pros and cons mechanisms of macrophages in IA progression are expected to achieve more efficient treatment interventions. In this review, we summarized the current advanced knowledge of macrophages activation, infiltration, polarization and inflammatory responses in IA occurrence and development, as well as the most relevant NF-κB, signal transducer and activator of transcription 1 (STAT1) and Toll-Like Receptor 4 (TLR4) regulatory signaling modulation. The understanding of macrophages regulatory mechanisms is important for IA patients' clinical outcomes. Gaining insight into the macrophages regulation potentially contributes to more precise IA interventions and will also greatly facilitate the development of novel medical therapy.

The relationship between autoimmune disorders and intracranial aneurysms in East Asian and European populations: a bidirectional and multivariable two-sample Mendelian randomization study.

It remains unclear about the pathogenesis of intracranial aneurysms (IAs) in the setting of autoimmune disorders (ADs). However, the underlying systemic inflammatory characteristics of ADs may affect IAs through shared inflammatory pathways. Therefore, this study was conducted to explore the relationship between ADs and IAs and assess causal effects. In this study, 6 common ADs were included to explore their causal relationship with IAs. Besides, a bidirectional two-sample univariable Mendelian randomization (UVMR) analysis was performed. In addition, the primary analysis was performed by the inverse variance weighted (IVW) and Bayesian weighted Mendelian randomization (BWMR) method, and a series of sensitivity analyses were performed to assess the robustness of the results. Further, the data related to ADs and IAs were collected from open genome-wide association study studies (GWASs) and the Cerebrovascular Disease Knowledge Portal (CDKP) (including 11,084 cases and 311,458 controls), respectively. These analyses were conducted based on both the East Asian and European populations. Moreover, 6 ADs were subject to grouping according to connective tissue disease, inflammatory bowel disease, and thyroid disease. On that basis, a multivariate MR (MVMR1) analysis was further performed to explore the independent causal relationship between each AD and IAs, and an MVMR 2 analysis was conducted to investigate such potential confounders as smoking, alcohol consumption, and systolic blood pressure. Finally, these results were verified based on the data from another GWAS of IAs. The UVMR analysis results demonstrated that systemic lupus erythematosus (SLE) was associated with a high risk of IAs in the East Asian population (IVW OR, 1.06; 95%CI, 1.02-1.11; p = 0.0065, UVMR), which was supported by the results of BWMR (OR, 1.06; 95%CI, 1.02-1.11; p = 0.0067, BWMR), MVMR1 (OR, 1.06; 95%CI, 1.01-1.10; p = 0.015, MVMR1), MVMR2 (OR, 1.05; 95%CI, 1.00-1.11; p = 0.049, MVMR2), and sensitivity analyses. The results in the validation group also suggested a causal relationship between SLE and IAs (IVW OR, 1.04; 95% CI, 1.00-1.09; p = 0.046). The reverse MR analysis results did not reveal a causal relationship between IAs and ADs. In this MR study, SLE was validated to be a risk factor for IAs in the East Asian population. Therefore, the management of IAs in patients with SLE should be highlighted to avoid stroke events.

Abstract 15566: Dissecting the Genetic Architecture of Intracranial Aneurysms

Introduction: The genetic risk of intracranial aneurysm (IA) development has been ascribed largely to smoking and hypertension. The contribution of IA risk loci to aberrant gene programs within cerebrovascular cell types remains unclear. Hypothesis: We hypothesized that candidate causal genes at IA susceptibility loci are enriched within extracellular matrix producing cell types. Methods: We identified participants enrolled in the Million Veterans Program (MVP) with and without IA. Thirty-two million genotyped and imputed variants were tested for association with IA using mixed effect regression modeling, controlling for age, sex, and population structure prior to external replication and meta-analysis. Candidate causal genes were prioritized through expression quantitative trait loci colocalization and transcriptome wide association studies. We constructed a cerebrovascular single nucleus RNA sequencing (snRNA-seq) dataset and integrated IA summary statistics to compute a ‘disease relevance score’ per nucleus using the scDRS pipeline. Cell type level analysis was used to assess association of cerebrovascular cell types with IA. Results: We identified 3165 participants (2280 European, 627 African, and 258 Hispanic ancestry) with and 592927 without IA in the MVP. After replication and meta-analysis with data from an additional 12273 cases and 591046 controls, we identified 22 loci (5 novel) associated with IA. We prioritized 16 candidate causal genes. Gene expression analysis of snRNA-seq genes revealed enrichment of several candidate genes, including EDNRA and PLCE1 within smooth muscle cells (SMCs) and pericytes. Integration of summary statistics and snRNA-seq data revealed significant association of matrix-producing pericytes and smooth muscle cell populations with IA. Conclusion: Here, we identify novel loci associated with IA and found enrichment of candidate causal genes in pericytes and SMCs. Integration of summary statistics with cerebrovascular snRNA-seq reveals association of cell-types involved in matrix production, suggesting an intrinsic deficit in matrix production and vascular integrity that may drive IA pathogenesis independent of systemic hypertension.

Neutrophils: Novel Contributors to Estrogen-Dependent Intracranial Aneurysm Rupture Via Neutrophil Extracellular Traps.

Background Intracranial aneurysms (IAs) are more prevalent in women than men, and aneurysmal subarachnoid hemorrhage disproportionately affects postmenopausal women. These sex differences suggest estrogen protects against IA progression that can lead to rupture, but the underlying mechanisms are not fully understood. Although studies have demonstrated estrogen regulates inflammatory processes that contribute to IA pathogenesis, the role of neutrophils remains to be characterized. Using a murine model, we tested our hypothesis that neutrophils contribute to IA pathophysiology in an estrogen-dependent manner. Methods and Results We compared neutrophil infiltration in C57BL/6 female mice that develop IAs to those with a normal circle of Willis. Next, we investigated the estrogen-dependent role of neutrophils in IA formation, rupture, and symptom-free survival using a neutrophil depletion antibody. Finally, we studied the role of neutrophil extracellular trap formation (NETosis) as an underlying mechanism of aneurysm progression. Mice that developed aneurysms had increased neutrophil infiltration compared with those with a normal circle of Willis. In estrogen-deficient female mice, both neutrophil depletion and NETosis inhibition decreased aneurysm rupture. In estrogen-deficient female mice treated with estrogen rescue and estrogen-intact female mice, neither neutrophil depletion nor NETosis inhibition affected IA formation, rupture, or symptom-free survival. Conclusions Neutrophils contribute to aneurysm rupture in an estrogen-dependent manner. NETosis appears to be an underlying mechanism for neutrophil-mediated IA rupture in estrogen deficiency. Targeting NETosis may lead to the development of novel therapeutics to protect against IA rupture in the setting of estrogen deficiency.

CypD induced ROS output promotes intracranial aneurysm formation and rupture by 8-OHdG/NLRP3/MMP9 pathway

Reactive Oxygen Species (ROS) are widely accepted as a pernicious factor in the progression of intracranial aneurysm (IA), which is eminently related to cell apoptosis and extracellular matrix degradation, but the mechanism remains to be elucidated. Recent evidence has identified that enhancement of Cyclophilin D (CypD) under stress conditions plays a critical role in ROS output, thus accelerating vascular destruction. However, no study has confirmed whether cypD is a detrimental mediator of cell apoptosis and extracellular matrix degradation in the setting of IA development. Our data indicated that endogenous cypD mRNA was significantly upregulated in human IA lesions and mouse IA wall, accompanied by higher level of ROS, MMPs and cell apoptosis. CypD−/− remarkably reversed vascular smooth muscle cells (VSMCs) apoptosis and elastic fiber degradation, and significantly decreased the incidence of aneurysm and ruptured aneurysm, together with the downregulation of ROS, 8-OHdG, NLRP3 and MMP9 in vivo and vitro. Furthermore, we demonstrated that blockade of cypD with CsA inhibited the above processes, thus preventing IA formation and rupture, these effects were highly dependent on ROS output. Mechanistically, we found that cypD directly interacts with ATP5B to promote ROS release in VSMCs, and 8-OHdG directly bind to NLRP3, which interacted with MMP9 to increased MMP9 level and activity in vivo and vitro. Our data expound an unexpected role of cypD in IA pathogenesis and an undescribed 8-OHdG/NLRP3/MMP9 pathway involved in accelerating VSMCs apoptosis and elastic fiber degradation. Repressing ROS output by CypD inhibition may be a promising therapeutic strategy for prevention IA development.