Differential gene expression in relation to the clinical characteristics of human brain arteriovenous malformations

Carvedilol suppresses ryanodine receptor-dependent Ca2+ bursts in human neurons bearing PSEN1 variants found in early onset Alzheimer's disease

Seizures are increasingly being recognized as the hallmark of Alzheimer's disease (AD). Neuronal hyperactivity can be a consequence of neuronal damage caused by abnormal amyloid β (Aß) depositions. However, it can also be a cell-autonomous phenomenon causing AD by Aß-independent mechanisms. Various studies using animal models have shown that Ca2+ is released from the endoplasmic reticulum (ER) via type 1 inositol triphosphate receptors (InsP3R1s) and ryanodine receptors (RyRs). To investigate which is the main pathophysiological mechanism in human neurons, we measured Ca2+ signaling in neural cells derived from three early-onset AD patients harboring Presenilin-1 variants (PSEN1 p.A246E, p.L286V, and p.M146L). Of these, it has been reported that PSEN1 p.A246E and p.L286V did not produce a significant amount of abnormal Aß. We found all PSEN1-mutant neurons, but not wild-type, caused abnormal Ca2+-bursts in a manner dependent on the calcium channel, Ryanodine Receptor 2 (RyR2). Indeed, carvedilol, an RyR2 inhibitor, and VK-II-86, an analog of carvedilol without the β-blocking effects, sufficiently eliminated the abnormal Ca2+ bursts. In contrast, Dantrolene, an inhibitor of RyR1 and RyR3, and Xestospongin c, an IP3R inhibitor, did not attenuate the Ca2+-bursts. The Western blotting showed that RyR2 expression was not affected by PSEN1 p.A246E, suggesting that the variant may activate the RyR2. The RNA-Seq data revealed that ER-stress responsive genes were increased, and mitochondrial Ca2+-transporter genes were decreased in PSEN1A246E cells compared to the WT neurons. Thus, we propose that aberrant Ca2+ signaling is a key link between human pathogenic PSEN1 variants and cell-intrinsic hyperactivity prior to deposition of abnormal Aß, offering prospects for the development of targeted prevention strategies for at-risk individuals.

HSPA6 and its role in cancers and other diseases

Heat Shock Protein Family A (Hsp70) Member 6 (HSPA6) (Online Mendelian Inheritance in Man: 140555) belongs to the HSP70 family and is a partially conserved inducible protein in mammals. The HSPA6 gene locates on the human chromosome 1q23.3 and encodes a protein containing two important structural domains: The N-terminal nucleotide-binding domain and the C-terminal substrate-binding domain. Currently, studies have found that HSPA6 not only plays a role in the tumorigenesis and tumor progresses but also causes non-tumor-related diseases. Furthermore, HSPA6 exhibits to inhibit tumorigenesis and tumor progression in some types of cancers but promotes in others. Even though HSPA6 research has increased, its exact roles and mechanisms are still unclear. This article reviews the structure, expression, function, research progress, possible mechanism, and perspective of HSPA6 in cancers and other diseases, highlighting its potential role as a targeted therapeutic and prognostic marker.

Review of treatment and therapeutic targets in brain arteriovenous malformation

Brain arteriovenous malformations (bAVM) are an important cause of intracranial hemorrhage (ICH), especially in younger patients. The pathogenesis of bAVM are largely unknown. Current understanding of bAVM etiology is based on studying genetic syndromes, animal models, and surgically resected specimens from patients. The identification of activating somatic mutations in the Kirsten rat sarcoma viral oncogene homologue (KRAS) gene and other mitogen-activated protein kinase (MAPK) pathway genes has opened up new avenues for bAVM study, leading to a paradigm shift to search for somatic, de novo mutations in sporadic bAVMs instead of focusing on inherited genetic mutations. Through the development of new models and understanding of pathways involved in maintaining normal vascular structure and functions, promising therapeutic targets have been identified and safety and efficacy studies are underway in animal models and in patients. The goal of this paper is to provide a thorough review or current diagnostic and treatment tools, known genes and key pathways involved in bAVM pathogenesis to summarize current treatment options and potential therapeutic targets uncovered by recent discoveries.

Abnormalities in the Von Willebrand-Angiopoietin Axis Contribute to Dysregulated Angiogenesis and Angiodysplasia in Children With a Glenn Circulation

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Children with a bidirectional superior cavopulmonary connection (Glenn circulation) develop dysregulated angiogenesis and pulmonary angiodysplasia in the form of arteriovenous malformations (AVMs). No targeted therapy exists.

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The von Willebrand factor (vWF)–angiopoietin axis plays a major role in normal angiogenesis, angiodysplasia, and AVM formation in multiple diseases.

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vWF and angiopoietin-2 (which destabilizes vessel formation) were abnormal in children with a Glenn circulation versus control children. Within Glenn patients, angiopoietin-1 (which stabilizes vessel formation) and angiogenesis were different in the systemic versus pulmonary circulation. Plasma angiopoietin-1 was lower in the pulmonary circulation of Glenn patients with pulmonary AVMs than Glenn patients without AVMs.

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In parallel, differences in multiple angiogenic and inflammatory signaling peptides were observed between Glenn patients and controls, which indicated derangements in multiple angiogenic pathways in Glenn patients.

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These findings support the novel hypothesis that abnormal vWF metabolism and angiopoietin signaling dysregulate angiogenesis and contribute to pulmonary AVM formation in children with a Glenn circulation.

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The vWF-angiopoietin axis may be a target to correct angiogenic imbalance and reduce pulmonary angiodysplasia in Glenn patients.

Children with a bidirectional superior cavopulmonary (Glenn) circulation develop angiodysplasia and pulmonary arteriovenous malformations (AVMs). The von Willebrand factor (vWF)–angiopoietin axis plays a major role in AVM formation in multiple diseases. We observed derangements in global angiogenic signaling, vWF metabolism, angiopoietins, and in vitro angiogenesis in children with a Glenn circulation versus controls and within Glenn pulmonary versus systemic circulations. These findings support the novel hypothesis that abnormalities in the vWF-angiopoietin axis may dysregulate angiogenesis and contribute to Glenn pulmonary AVMs. The vWF-angiopoietin axis may be a target to correct angiogenic imbalance in Glenn patients, for whom no targeted therapy exists.

Neurovascular inflammation in the pathogenesis of brain arteriovenous malformations

Brain arteriovenous malformations (bAVM) arise as congenital or sporadic focal lesions with a significant risk for intracerebral hemorrhage (ICH). A wide range of interindividual differences is present in the onset, progression, and severity of bAVM. A growing body of gene expression and polymorphism-based research studies support the involvement of localized inflammation in bAVM disease progression and rupture. In this review article, we analyze the altered responses of neural, vascular, and immune cell types that contribute to the inflammatory process, which exacerbates the pathophysiological progression of vascular dysmorphogenesis in bAVM lesions. The cumulative effect of inflammation in bAVM development is orchestrated by various genetic moderators and inflammatory mediators. We also discuss the potential therapies for the treatment of brain AVM by targeting the inflammatory processes and mediators. Elucidating the precise role of inflammation in the bAVM growth and hemorrhage would open novel avenues for noninvasive and effectual causal therapy that may complement the current therapeutic strategies.

Basic research and surgical techniques for brain arteriovenous malformations

Arteriovenous malformations (AVMs) are hemorrhagic vascular diseases in which arteries and veins are directly connected with no capillary bed between the two. We herein introduce the results of basic research of this disease and surgical techniques based on our data and experiences. The results obtained from our research show that cell death- and inflammation-related molecules changed or became activated compared with control specimens. These findings indicate that chronic inflammation occurs in and around the nidus of AVMs. Various molecules are involved in the mechanisms of cell death and angiogenesis during this process. Confirmation of blood flow in the nidus is very important to avoid hemorrhagic complications during surgical removal of the nidus. The risk of hemorrhage increases when the blood flow in the nidus is not reduced. We reported the advantages of serial indocyanine green videoangiography, which is used to assess the blood flow during AVM nidus removal. Since publication of the ARUBA trial and Scottish Audit, treatments with high morbidity have not been allowed. It is especially important for neurosurgeons to treat low Spetzler-Martin grade AVMs with low morbidity. J. Med. Invest. 67 : 222-228, August, 2020.

Deciphering the vascular labyrinth: role of microRNAs and candidate gene SNPs in brain AVM development - literature review

Background: Brain arteriovenous malformations (AVMs) are a relatively infrequent vascular pathology of unknown etiology that, despite their rarity, cause the highest number of hemorrhagic strokes under the age of 30 years. They pose a challenge to all forms of treatment due to their variable morphology, location, size, and, last but not least, evolving nature. MicroRNAs (miRNAs) are non-coding RNA strands that may suppress the expression of target genes by binding completely or partially to their complementary sequences. Single nucleotide polymorphisms (SNPs), as the name implies, are variations in a single nucleotide in the DNA, usually found in the non-coding segments. Although the majority of SNPs are harmless, some located in the proximity of candidate genes may result in altered expression or function of these genes and cause diseases or affect how different pathologies react to treatment. The roles miRNAs and certain SNPs play in the development and growth of AVMs are currently uncertain, yet progress in deciphering the minutiae of this pathology is already visible. Methods and Results: We performed an electronic Medline (PubMed, PubMed Central) and Google Academic exploration using permutations of the terms: "arteriovenous malformations," "single nucleotide polymorphisms," "microRNA," "non-coding RNA," and "genetic mutations." The findings were then divided into two categories, namely the miRNAs and the candidate gene SNPs associated with AVMs respectively. 6 miRNAs and 12 candidate gene SNPs were identified and discussed. Conclusions: The following literature review focuses on the discoveries made in ascertaining the different implications of miRNAs and candidate gene SNPs in the formation and evolution of brain AVMs, as well as highlighting the possible directions of future research and biological treatment. Abbreviations: ACVRL1/ALK1: activin receptor-like kinase 1; Akt: protein kinase B; ANGPTL4: angiopoietin-like 4; ANRIL: antisense noncoding RNA in the INK4 locus; AVM: arteriovenous malformation; AVM-BEC: arteriovenous malformation brain endothelial cell; BRCA1: breast cancer type 1 susceptibility protein; CCS: case-control study; CDKN2A/B: cyclin-dependent kinase inhibitor 2A/B; CLTC: clathrin heavy chain; DNA: deoxyribonucleic acid; ERK: extracellular signal-regulated kinase; GPR124: probable G-protein coupled receptor 124; GWAS: genome-wide association study; HHT: hereditary hemorrhagic telangiectasia; HIF1A: hypoxia-inducible factor 1A; IA: intracranial aneurysm; ICH: intracranial hemorrhage; Id-1: inhibitor of DNA-binding protein A; IL-17: interleukin 17; MAP4K3: mitogen-activated protein kinase kinase kinase kinase 3; miRNA: microRNA; MMP: matrix metalloproteinase; NFkB: nuclear factor kappa-light-chain of activated B cells; NOTCH: neurogenic locus notch homolog; p38MAPK: p38 mitogen-activated protein kinase; PI3K: phosphoinositide 3-kinase; RBBP8: retinoblastoma-binding protein 8; RNA: ribonucleic acid; SNAI1: Snail Family Transcriptional Repressor 1; SNP: single nucleotide polymorphism; SOX-17: SRY-related HMG-box; TGF-β: transformation growth factor β; TGFR: transformation growth factor receptor; TIMP-4, tissue inhibitor of metalloproteinase 4; TSP-1: thrombospondin-1; UTR: untranslated region; VEGF: Vascular Endothelial Growth Factor; VSMC: vascular smooth muscle cell; Wnt1: Wnt family member 1.

RNA-Sequencing Highlights Inflammation and Impaired Integrity of the Vascular Wall in Brain Arteriovenous Malformations

Background and Purpose—

Interventional treatment of unruptured brain arteriovenous malformations (BAVMs) has become increasingly controversial. Because medical therapy is still lacking, we aimed to obtain insight into the disease mechanisms implicated in BAVMs and to identify potential targets for medical treatment to prevent rupture of a BAVM.

Methods—

We used next-generation RNA sequencing to identify differential expression on a transcriptome-wide level comparing tissue samples of 12 BAVMs to 16 intracranial control arteries. We identified differentially expressed genes by negative binominal generalized log-linear regression (false discovery rate corrected P <0.05). We selected 10 genes for validation using droplet digital polymerase chain reaction. We performed functional pathway analysis accounting for potential gene-length bias, to establish enhancement of biological pathways involved in BAVMs. We further assessed which Gene Ontology terms were enriched.

Results—

We found 736 upregulated genes in BAVMs including genes implicated in the cytoskeletal machinery and cell-migration and genes encoding for inflammatory cytokines and secretory products of neutrophils and macrophages. Furthermore, we found 498 genes downregulated including genes implicated in extracellular matrix composition, the binary angiopoietin-TIE system, and TGF (transforming growth factor)-β signaling. We confirmed the differential expression of top 10 ranked genes. Functional pathway analysis showed enrichment of the protein digestion and absorption pathway (false discovery rate-adjusted P =1.70×10 −2 ). We identified 47 enriched Gene Ontology terms (false discovery rate-adjusted P <0.05) implicated in cytoskeleton network, cell-migration, endoplasmic reticulum, transmembrane transport, and extracellular matrix composition.

Conclusions—

Our genome-wide RNA-sequencing study points to involvement of inflammatory mediators, loss of cerebrovascular quiescence, and impaired integrity of the vascular wall in the pathophysiology of BAVMs. Our study may lend support to potential receptivity of BAVMs to medical therapeutics, including those promoting vessel maturation, and anti-inflammatory and immune-modifying drugs.

RNA Sequencing Reveals the Activation of Wnt Signaling in Low Flow Rate Brain Arteriovenous Malformations

Background

The blood flow rate of brain arteriovenous malformations (bAVMs) is an important clinical characteristic closely associated with the hemorrhage risk and radiosurgery obliteration rate of bAVMs. However, the underlying molecular properties remain unclear. To identify potential key molecules, signaling pathways, and vascular cell types involved, we compared gene expression profiles between bAVMs with high flow rates and low flow rates (LFR) and validated the functions of selected key molecules in vitro.

Methods and Results

We performed RNA‐sequencing analysis on 51 samples, including 14 high flow rate bAVMs and 37 LFR bAVMs. Functional pathway analysis was performed to identify potential signals influencing the flow rate phenotype of bAVMs. Candidate genes were investigated in bAVM specimens by immunohistochemical staining. Migration, tube formation, and proliferation assays were used to test the effects of candidate genes on the phenotypic properties of cultured human umbilical vein endothelial cells and human brain vascular smooth muscle cells. We identified 250 upregulated and 118 downregulated genes in LFR bAVMs compared with high flow rate bAVMs. Wnt signaling was activated in the LFR group via upregulation of FZD10 and MYOC. Immunohistochemical staining showed that vascular endothelial and smooth muscle cells of LFR bAVMs exhibited increased FZD10 and MYOC expression. Experimentally elevating these genes promoted human umbilical vein endothelial cells and migration and tube formation by activating canonical Wnt signaling in vitro.

Conclusions

Our results suggest that canonical Wnt signaling mediated by FZD10 and MYOC is activated in vascular endothelial and smooth muscle cells in LFR bAVMs.

LncRNAs expression signatures of human brain arteriovenous malformation revealed by microarray

Long noncoding RNAs (LncRNAs) were important genes involved in a variety of biological functions. They are aberrantly expressed in many types of diseases. In this study, we described LncRNAs profiles in 4 pairs of human brain arteriovenous malformation(AVM) and the corresponding fragment of superior temporal arteries(STA) or small scalp arteries (controlled arteries, CA) and try to find LncRNAs that correlated with the human brain AVM and with clinical symptoms.4 pairs of AVM tissues and corresponding STA or scalp artery fragments (depended on the operative approach) of 4 AVM patients who were admitted in Beijing TianTan hospital were collected. Then LncRNA and mRNA expression profiling analysis was performed by Arraystar-LncRNA array. From the data, we found 1931 LncRNAs upregulated (>2 folds) and 1852 downregulated (<2 folds) in total 28,012 LncRNAs that could be detected. We also found 1577 upregulated mRNAs (>2 folds) and 1699 downregulated (<2 folds) in 21,780 mRNAs that could be detected. LncRNAs (ENST00000423394, ENST00000444114, TCONS_00013855, and ENST00000452148) were evaluated by qPCR in 14 pairs of AVM nidus and the control. This 4 LncRNAs were aberrantly expressed in AVM nidus compared with the control. LncRNA (ENST00000423394) correlated with epilepsy (R = 0.34, P = .02, 95% confidence interval 0.08-0.85)We found that development of AVM may correspond with downregulation of NADPH reductase, lipoprotein lipase and Optic atrophy related proteins. It also may correspond with upregulation of Fcγreceptor. The downregulation of NADPH reductase may correlate with seizures of AVM patients.

Neovasculature can be induced by patching an arterial graft into a vein: A novel in vivo model of spontaneous arteriovenous fistula formation

Arteriovenous malformations consist of tangles of arteries and veins that are often connected by a fistula. The causes and mechanisms of these clinical entities are not fully understood. We discovered that suturing an arterial patch into the common jugular vein of rabbits led to spontaneous neovascularization, the formation of an arteriovenous fistula and the development of an arteriovenous shunt. An arterial patch excised from the common carotid artery was sutured into the common jugular vein. Within a month, a dense nidus-like neovasculature formed around the patch. Angiography and pulse-oximeter analyses showed that the blood flowing into the neovasculature was arterial blood. This indicated that an arteriovenous shunt had formed. Fluorescence in situ hybridization with a Y chromosome probe in female rabbits that received an arterial patch from male rabbits showed that the vessels close to the graft bore the Y chromosome, whereas the vessels further away did not. Enzyme-linked immunosorbent assays and cDNA microarray analysis showed that multiple angiogenic factors were upregulated after patch transplantation. This is the first in vivo model of spontaneous arteriovenous fistula formation. Further research on these differences may help to improve understanding of human vascular anomaly diseases and the basic principles underlying vasculogenesis and/or angiogenesis.

Magnetic Resonance (MR) Imaging of Vascular Malformations

Vascular malformations pose a diagnostic and therapeutic challenge due to the broad differential diagnosis as well as common utilization of inadequate or inaccurate classification systems among healthcare providers. Therapeutic approaches to these lesions vary based on the type, size, and extent of the vascular anomaly, necessitating accurate diagnosis and classification. Magnetic resonance (MR) imaging (MRI) is an effective modality for classifying vascular anomalies due to its ability to delineate the extent and anatomic relationship of the malformation to adjacent structures. In addition to anatomical mapping, the complete evaluation of vascular anomalies includes hemodynamic characterization. Dynamic time-resolved contrast-enhanced MR angiography provides information regarding hemodynamics of vascular anomalies, differentiating high- and low-flow vascular malformations. Radiologists must identify the MRI features of vascular malformations for better diagnosis and classification.

MicroRNA-137 and microRNA-195* inhibit vasculogenesis in brain arteriovenous malformations

OBJECTIVE

Brain arteriovenous malformations (AVMs) are the most common cause of nontraumatic intracerebral hemorrhage in young adults. The genesis of brain AVM remains enigmatic. We investigated microRNA (miRNA) expression and its contribution to the pathogenesis of brain AVMs.

METHODS

We used a large-scale miRNA analysis of 16 samples including AVMs, hemangioblastoma, and controls to identify a distinct AVM miRNA signature. AVM smooth muscle cells (AVMSMCs) were isolated and identified by flow cytometry and immunohistochemistry, and candidate miRNAs were then tested in these cells. Migration, tube formation, and CCK-8-induced proliferation assays were used to test the effect of the miRNAs on phenotypic properties of AVMSMCs. A quantitative proteomics approach was used to identify protein expression changes in AVMSMCs treated with miRNA mimics.

RESULTS

A distinct AVM miRNA signature comprising a large portion of lowly expressed miRNAs was identified. Among these miRNAs, miR-137 and miR-195* levels were significantly decreased in AVMs and constituent AVMSMCs. Experimentally elevating the level of these microRNAs inhibited AVMSMC migration, tube formation, and survival in vitro and the formation of vascular rings in vivo. Proteomics showed the protein expression signature of AVMSMCs and identified downstream proteins regulated by miR-137 and miR-195* that were key signaling proteins involved in vessel development.

INTERPRETATION

Our results indicate that miR-137 and miR-195* act as vasculogenic suppressors in AVMs by altering phenotypic properties of AVMSMCs, and that the absence of miR-137 and miR-195* expression leads to abnormal vasculogenesis. Ann Neurol 2017;82:371-384.

Neuropathology of cerebrovascular diseases

The chapter describes the epidemiology of cerebrovascular diseases, anatomy of the cerebral blood vessels, pathophysiology of ischemia, hypoxia, hypoxemia, anemic hypoxia, histotoxic hypoxia, carbon monoxide damage, hyperoxid brain damage and decompression sickness, and selective cell and regional vulnerability; diseases of the blood vessels including atherosclerosis, hypertensive angiopathy, small vessel disease, inflammatory vascular diseases, cerebral amyloid angiopathies, CADASIL, CARASIL and other diseases that can lead to cerebrovascular occlusion; intracranial and intraspinal aneurysms and vascular malformations; hematologic disorders that can cause cerebral infarct or hemorrhage; brain ischemic damage; and spontaneous intracranial bleeding. Within ischemic brain damage, focal cerebral ischemia, hemorrhagic infarct, brain edema, penumbra, global cerebral ischemia, venous thrombosis, lacunas and lacunar state, status cribosus, granular atrophy of the cerebral cortex, hippocampal sclerosis, vascular leukoencephalopathy Binswanger type and multi-infarct encephalopathy are discussed in detail. Cognitive impairment of vascular origin deserves an individual section.

The Effect of Acute and Chronic Social Stress on the Hippocampal Transcriptome in Mice

Psychogenic stress contributes to the formation of brain pathology. Using gene expression microarrays, we analyzed the hippocampal transcriptome of mice subjected to acute and chronic social stress of different duration. The longest period of social stress altered the expression of the highest number of genes and most of the stress-induced changes in transcription were reversible after 5 days of rest. Chronic stress affected genes involved in the functioning of the vascular system (Alas2, Hbb-b1, Hba-a2, Hba-a1), injury response (Vwf, Mgp, Cfh, Fbln5, Col3a1, Ctgf) and inflammation (S100a8, S100a9, Ctla2a, Ctla2b, Lcn2, Lrg1, Rsad2, Isg20). The results suggest that stress may affect brain functions through the stress-induced dysfunction of the vascular system. An important issue raised in our work is also the risk of the contamination of brain tissue samples with choroid plexus. Such contamination would result in a consistent up- or down-regulation of genes, such as Ttr, Igf2, Igfbp2, Prlr, Enpp2, Sostdc1, 1500015O10RIK (Ecrg4), Kl, Clic6, Kcne2, F5, Slc4a5, and Aqp1. Our study suggests that some of the previously reported, supposedly specific changes in hippocampal gene expression, may be a result of the inclusion of choroid plexus in the hippocampal samples.

Immunohistochemical Analysis of Sox17 Associated Pathway in Brain Arteriovenous Malformations

BACKGROUND

Sox17 has emerged as an important factor in vascular remodeling because of the potential linkage with Wnt/β-catenin, Notch, and the inflammatory pathway. Brain arteriovenous malformation (BAVM), as an angiogenic and inflammatory disorder, might possess an aberrant regulation of the Sox17 associated pathway. We sought to investigate the expression of the Sox17 associated pathway in BAVMs.

METHODS

Using immunohistochemical methods, 16 paraffin specimens of BAVM nidus were analyzed. Specimens were obtained from patients during surgical procedures.

RESULTS

Expression of Sox17, Hey1, and β-catenin was observed in all specimens. Large veins possessed a distinct pattern of expression; thick-walled veins had a stronger intensity, whereas thin-walled veins had a weaker intensity, of Sox17, Hey1, and β-catenin (P < 0.001). Thick-walled veins also had a higher expression of Sox17, Hey1, and β-catenin compared with large arteries (P < 0.05). Hey1 and β-catenin expression was also higher in thick-walled veins compared with brain microvessels (P < 0.01). In addition, the difference in expression of the Sox17 associated pathway (Hey1 and β-catenin) was observed in medium and small arteries compared with large arteries in BAVM nidus and brain microvessels (P < 0.01).

CONCLUSIONS

The Sox17 associated pathway was activated in the BAVM nidus. Our results indicate that arterial identity is gained in thick-walled veins; this might reflect the process of arterialization of the veins as a result of hemodynamic stress. In addition, high expression of the Sox17 associated pathway in medium and small arteries indicates that BAVM vessels are intrinsically active.

Molecular and cellular biology of cerebral arteriovenous malformations: a review of current concepts and future trends in treatment

OBJECT

Arteriovenous malformations (AVMs) are classically described as congenital static lesions. However, in addition to rupturing, AVMs can undergo growth, remodeling, and regression. These phenomena are directly related to cellular, molecular, and physiological processes. Understanding these relationships is essential to direct future diagnostic and therapeutic strategies. The authors performed a search of the contemporary literature to review current information regarding the molecular and cellular biology of AVMs and how this biology will impact their potential future management.

METHODS

A PubMed search was performed using the key words "genetic," "molecular," "brain," "cerebral," "arteriovenous," "malformation," "rupture," "management," "embolization," and "radiosurgery." Only English-language papers were considered. The reference lists of all papers selected for full-text assessment were reviewed.

RESULTS

Current concepts in genetic polymorphisms, growth factors, angiopoietins, apoptosis, endothelial cells, pathophysiology, clinical syndromes, medical treatment (including tetracycline and microRNA-18a), radiation therapy, endovascular embolization, and surgical treatment as they apply to AVMs are discussed.

CONCLUSIONS

Understanding the complex cellular biology, physiology, hemodynamics, and flow-related phenomena of AVMs is critical for defining and predicting their behavior, developing novel drug treatments, and improving endovascular and surgical therapies.

Social stress increases expression of hemoglobin genes in mouse prefrontal cortex

BACKGROUND

In order to better understand the effects of social stress on the prefrontal cortex, we investigated gene expression in mice subjected to acute and repeated social encounters of different duration using microarrays.

RESULTS

The most important finding was identification of hemoglobin genes (Hbb-b1, Hbb-b2, Hba-a1, Hba-a2, Beta-S) as potential markers of chronic social stress in mice. Expression of these genes was progressively increased in animals subjected to 8 and 13 days of repeated stress and was correlated with altered expression of Mgp (Mglap), Fbln1, 1500015O10Rik (Ecrg4), SLC16A10, and Mndal. Chronic stress increased also expression of Timp1 and Ppbp that are involved in reaction to vascular injury. Acute stress did not affect expression of hemoglobin genes but it altered expression of Fam107a (Drr1) and Agxt2l1 (Etnppl) that have been implicated in psychiatric diseases.

CONCLUSIONS

The observed up-regulation of genes associated with vascular system and brain injury suggests that stressful social encounters may affect brain function through the stress-induced dysfunction of the vascular system.