Arteriovenous Malformation Tissue Research Articles

MicroRNA-135b-5p Is a Pathologic Biomarker in the Endothelial Cells of Arteriovenous Malformations.

Arteriovenous malformations (AVMs) are congenital vascular anomalies with a poor prognosis. AVMs are considered intractable diseases, as there is no established approach for early diagnosis and treatment. Therefore, this study aimed to provide new evidence by analyzing microRNAs (miRNAs) associated with AVM. We present fundamental evidence for the early diagnosis and treatment of AVM by analyzing miRNAs in the endothelial cells of AVMs. This study performed sequencing and validation of miRNAs in endothelial cells from normal and AVM tissues. Five upregulated and two downregulated miRNAs were subsequently analyzed under hypoxia and vascular endothelial growth factor (VEGF) treatment by one-way analysis of variance (ANOVA). Under hypoxic conditions, miR-135b-5p was significantly upregulated in the AVM compared to that under normal conditions, corresponding to increased endothelial activity (p-value = 0.0238). VEGF treatment showed no significant increase in miR-135b-5p under normal conditions, however, a surge in AVM was observed. Under both hypoxia and VEGF treatment, comparison indicated a downregulation of miR-135b-5p in AVM. Therefore, miR-135b-5p was assumed to affect the pathophysiological process of AVM and might play a vital role as a potential biomarker of AVMs for application related to diagnosis and treatment.

Relative expression of hormone receptors by endothelial and smooth muscle cells in proliferative and non-proliferative areas of congenital arteriovenous malformations

BackgroundEpisodic growth due to microvascular proliferations (MVP) has been reported in congenital arteriovenous malformations (AVM), which are normally quiescent lesions composed of mature malformed vessels. Since AVM also may worsen under conditions of hormonal dysregulation, we hypothesized that hormonal influences may stimulate this process of vasoproliferative growth through potential interactions with hormone receptors (HR).Methods13 Cases of AVM tissue with histologically documented vasoproliferative growth were analyzed quantitatively for the presence and tissue localization of estrogen receptor (ER), progesterone receptor (PGR), growth hormone receptor (GHR) and follicle-stimulating hormone receptor (FSHR) in relation to resident cells of interest (endothelial cells (EC), smooth muscle cells (SMC) and mast cells (MC)) by applying multiplex immunohistochemistry (IHC) staining. Expression patterns in lesions with MVP and mature vessels were quantified and compared. Available fresh frozen tissues of 3 AVM samples were used to confirm the presence of HR using Reverse-Transcriptase quantitative Polymerase Chain Reaction (RT-qPCR).ResultsAll four HR studied were expressed in all cases within EC and SMC in areas of MVP and mature vessels, but not in normal skin tissue. ER, GHR, and FSHR showed more expression in EC of MVP and in SMC of mature vessels. RT-qPCR confirmed presence of all 4 HR in both areas.ConclusionExpression of ER, PGR, GHR, and FSHR in vasoproliferative areas of congenital AVM could explain onset of sudden symptomatic growth, as has observed in a subpopulation of patients. These findings may have implications for eventual anti-hormonal targeted therapy in the lesions involved.

Extracranial arteriovenous malformations demonstrate dysregulated TGF-β/BMP signaling and increased circulating TGF-β1

Extracranial arteriovenous malformations (AVMs) are characterized by anomalous arterial-to-venous connections, aberrant angiogenesis, local inflammation and hypoxia, and disorganized histological architecture; however, the precise molecular perturbations leading to this phenotype remain elusive. We hypothesized that extracranial AVM tissue would demonstrate deregulation of the TGF-β/BMP signaling pathway, which may serve as a potential target in the development of molecular-based therapies for AVMs. AVM tissue was harvested during resection from 10 patients with AVMs and compared to control tissue. Blood was collected from 14 AVM patients and 10 patients without AVMs as controls. Expression of TGF-β/BMP pathway components was analyzed using RT-PCR, western blotting, and immunohistochemistry. Circulating levels of TGF-β1 were analyzed by ELISA. Paired t tests were utilized to perform statistical analysis. The mRNA levels of TGF-β1, ALK1, Endoglin (ENG), Smad6, Smad7, and Smad8 were significantly elevated in AVM tissue when compared to controls. Protein levels of TGF-β1 and Smad3 were elevated in AVM tissue while protein levels of BMP-9, ALK1, Smad1, Smad6, and Smad8 were significantly decreased in AVMs. Immunohistochemistry demonstrated increased TGF-β1 in the perivascular cells of AVMs compared to normal controls, and circulating levels of TGF-β1 were significantly higher in AVM patients. Patients with AVMs demonstrate aberrant TGF-β/BMP expression in AVM tissue and blood compared to controls. Targeting aberrantly expressed components of the TGF-β/BMP pathway in extracranial AVMs may be a viable approach in the development of novel molecular therapies, and monitoring circulating TGF-β1 levels may be a useful indicator of treatment success.

Hypoxia Promotes Angiogenic Effect in Extracranial Arteriovenous Malformation Endothelial Cells.

Arteriovenous malformation (AVM) is characterized by high-flow blood vessels connecting arteries and veins without capillaries. This disease shows increased angiogenesis and a pathophysiological hypoxic environment in proximal tissues. Here, we analyzed the effects of hypoxia on angiogenesis in the endothelial cells (ECs) of AVM and normal tissues. ECs from human normal and AVM tissues were evaluated using immunocytochemistry with CD31. In vitro tube formation under hypoxia was tested in both ECs using Matrigel. The relative expression of angiogenesis-related genes was measured using real-time PCR. Under normoxia, CD31 was significantly higher in AVM ECs (79.23 ± 0.65%) than in normal ECs (74.15 ± 0.70%). Similar results were observed under hypoxia in AVM ECs (63.85 ± 1.84%) and normal ECs (60.52 ± 0.51%). In the tube formation test under normoxic and hypoxic conditions, the junction count and total vessel length were significantly greater in AVM ECs than normal ECs. Under both normoxia and hypoxia, the angiogenesis-related gene FSTL1 showed a significantly higher expression in AVM ECs than in normal ECs. Under hypoxia, CSPG4 expression was significantly lower in AVM ECs than in normal ECs. Accordingly, the angiogenic effect was increased in AVM ECs compared with that in normal ECs. These results provide a basic knowledge for an AVM treatment strategy.

Wall shear stress on vascular smooth muscle cells exerts angiogenic effects on extracranial arteriovenous malformations.

BackgroundIn addition to vascular endothelial cells, vascular smooth muscle cells (VSMCs) are subject to continuous shear stress because of blood circulation. The angiogenic properties of VSMCs in extracranial arteriovenous malformations (AVMs) may exceed those of normal blood vessels if the body responds more sensitively to mechanical stimuli. This study was performed to investigate the hypothesis that rapid angiogenesis may be achieved by mechanical shear stress.MethodsVSMCs were obtained from six patients who had AVMs and six normal controls. The target genes were set to angiopoietin-2 (AGP2), aquaporin-1 (AQP1), and transforming growth factor-beta receptor 1 (TGFBR1). Reverse-transcriptase polymerase chain reaction (RT-PCR) and real-time PCR were implemented to identify the expression levels for target genes. Immunofluorescence was also conducted.ResultsUnder the shear stress condition, mean relative quantity values of AGP2, AQP1, and TGFBR1 in AVM tissues were 1.927±0.528, 1.291±0.031, and 2.284±1.461 when compared with neutral conditions. The expression levels of all three genes in AVMs were higher than those in normal tissue except for AQP1 under shear stress conditions. Immunofluorescence also revealed increased staining of shear stress-induced genes in the normal tissue and in AVM tissue.ConclusionsShear stress made the VSMCs of AVMs more sensitive. Although the pathogenesis of AVMs remains unclear, our study showed that biomechanical stimulation imposed by shear stress may aggravate angiogenesis in AVMs.

Expression of Cathepsins B, D, and G in Extracranial Arterio-Venous Malformation.

Objectives: We have previously identified a population of cells that expressed stemness-associated markers in extracranial arterio-venous malformation (AVM) and demonstrated expression of cathepsins B, D, and G on embryonic stem cell (ESC)-like populations in other vascular anomalies. This study investigated the expression of cathepsins B, D, and G, and their localization in relation to this primitive population in extracranial AVM.Methods: Immunohistochemical staining was performed on AVM tissue samples from 13 patients to demonstrate expression of cathepsins B, D, and G. Western blotting was performed on four AVM tissue samples and three AVM-derived primary cell lines to confirm protein expression of cathepsins B and D proteins. RT-qPCR was performed on three AVM-derived primary cell lines to demonstrate transcript expression of cathepsins B, D, and G. Enzymatic activity assays were performed on three AVM-derived primary cell lines to investigate if cathepsins B and D were active. Localization of the cathepsins was investigated using immunofluorescence dual-staining of the cathepsins with the ESC markers OCT4 and SOX2, and mast cells marker chymase on two of the 13 AVM tissue samples.Results: Immunohistochemical staining demonstrated expression of cathepsins B, D, and G in all 13 AVM tissue samples. Western blotting showed expression of cathepsins B and D proteins in all four AVM tissue samples and all three AVM-derived primary cell lines. RT-qPCR demonstrated transcripts of cathepsins B, D, and G in all three AVM-derived primary cell lines. Enzymatic activity assays showed that cathepsins B and D were active. Immunofluorescence staining showed expression of cathepsins B and D on the OCT4+/SOX2+ endothelium and media of the lesional vessels and cells within the stroma in AVM nidus. Cathepsin G was expressed on the chymase+ phenotypic mast cells.Conclusions: This study demonstrated the novel finding of the expression of cathepsins B, D, and G in AVM. Cathepsins B and D were expressed by the primitive population, and cathepsin G was localized to mast cells, within the AVM nidus.

Oscillatory shear stress promotes angiogenic effects in arteriovenous malformations endothelial cells

BackgroundVascular endothelial cells (ECs) are subject to continuous shear stress due to blood circulation. Mechanical stress due to high shear flow can also cause arteriovenous malformation (AVM) when ECs respond hyper-sensitively to shear flow. This study was conducted to test the hypothesis that angiogenesis could be promoted in response to mechanical stress via regulation of pro-angiogenic factors in AVM cells.MethodsECs were extracted from the tissue samples from six AVM patients and six normal patients. Shear stress at 7 dynes/cm2 were applied for 24 h. Before and after application of shear stress to each group, RT-PCR was performed to access the expression levels of angiopoietin2(AGP2), aquaporin1(AQP1) and TGFβR1. Immunofluorescences was also performed to evaluate the level of protein expressions.ResultsIn both normal and AVM tissues, AGP2 and TGFβR1 under the shear stress showed increased expression in the ECs compared to the non-sheared samples. When AVMs and normal arterial vasculature were compared, the expression levels of both AGP2 and TGFβR1 in AVMs were higher when compared to normal arterial vasculature with or without shear stress. Immunofluorescence-based protein analysis also confirmed shear-induced AGP2 and TGFβR1 in both samples of normal and AVM patients.ConclusionsAVMs exhibited higher sensitivity to shear stress by producing higher expressions of some marked genes and proteins that regulate the endothelial functions upon exposure to shear stress. While the physiological mechanism for AVMs remain elusive, our study shows the plausibility of physical stress imposed by the shearing flow can cause the occurrence of AVMs.

Stemness-Associated Markers Are Expressed in Extracranial Arteriovenous Malformation.

Objectives: Arteriovenous malformation (AVM) consists of a nidus with poorly formed low-resistance vessels in place of a functional capillary network. The role of somatic mutations in embryonic stem cells (ESCs) and vascular anomalies and the presence of primitive populations in vascular anomalies led us to investigate the presence of a primitive population in extracranial AVM.Methods: Extracranial AVM tissue samples from 12 patients were stained for stemness-associated markers OCT4, SOX2, NANOG, KLF4, and c-MYC using immunohistochemical staining. In situ hybridization (ISH) was performed on six tissue samples to determine transcript expression. Western blotting and RT-qPCR were performed on two AVM-derived primary cell lines to determine protein and transcript expression of these markers, respectively. Immunofluorescence staining was performed on two tissue samples to investigate marker co-localization.Results: Immunohistochemical staining demonstrated the expression of OCT4, SOX2, KLF4, and c-MYC on the endothelium and media of lesional vessels and cells within the stroma of the nidus in all 12 AVM tissue samples. ISH and RT-qPCR confirmed transcript expression of all five markers. Western blotting showed protein expression of all markers except NANOG. Immunofluorescence staining demonstrated an OCT4+/SOX2+/KLF4+/c-MYC+ population within the endothelium and media of the lesional vessels and cells within the stroma of the AVM nidus.Conclusions: Our findings may suggest the presence of a primitive population within the AVM nidus. Further investigation may lead to novel therapeutic targeting of this population.

CTCFL expression is associated with cerebral vascular abnormalities

CTCFL is expressed in testis, oocytes and embryonic stem cells, and is aberrantly expressed in malignant cells, and is classified as a cancer-testis gene. We have previously shown by using a tetracycline-inducible Ctcfl transgene that inappropriate expression of Ctcfl negatively impacts fetal development and causes early postnatal lethality in the mouse. The affected pups displayed severe vascular abnormalities and localized hemorrhages in the brain evocative of cerebral cavernous malformations (CCM) and arteriovenous malformations (AVM) in humans. Thus, we aim to analyze; a) the presence of CCM-related proteins CCM1/KRIT1, CCM2/malcavernin and CCM3/PDCD10 in Ctcfl transgenic animals and, b) whether there is CTCFL expression in human CCM and AVM tissues. Ctcfl transgenic animals exhibited increased CD31 expression in vascular areas of the dermis and periadnexal regions but no difference was observed for vWF and α-SMA expressions. CCM-related proteins CCM1/KRIT1, CCM2/malcavernin and CCM3/PDCD10 were aberrantly expressed in coronal sections of the head in transgenic animals. We also observed CTCFL expression in human CCMs and AVMs. The induced expression of CTCFL resulting in vascular brain malformations in mice combined with the presence of CTCFL in human vascular malformations provide new insights into the role of this gene in vascular development in humans.

Analysis of the Related Risk Factors of Cerebral AVM Hemorrhage and the Relationship Between EPCs and SDF-1 in Brain AVM

To explore the related risk factors of hemorrhage in human brain cerebral arteriovenous malformations (AVM) and the relationship between endothelial progenitor cells (EPCs) content and stromal cell-derived factor-1 (SDF-1) in different ages. A retrospective analysis was conducted on 130 patients with cerebral AVM who underwent surgical treatment from May 2012 to October 2018. Univariate and multivariate logistic analysis was used to investigate the related risk factors of cerebral AVM hemorrhage. Forty paraffin specimens of human brain AVM were harvested from 24 cases of cerebral hemorrhage patients and 16 cases of non-cerebral hemorrhage patients Paraffin samples of cerebral cortex from 8 patients with epilepsy during the same period were selected as control. Positive expression of CD34 and vascular endothelial growth factor receptor 2 (KDR2) in brain tissue samples of both groups were used to identify EPCs. Immunofluorescence double staining was used for KDR2 and CD34 positive localization to determine EPCs localization, and SDF-1 expression detection was performed. The size of brain AVM<3 cm, deep brain AVM and single venous drainage are independent risk factors for cerebral AVM hemorrhage. Immunohistochemical results showed that CD34 and KDR2 were expressed in cerebral AVM group, but not in the control group. Double immunofluorescence staining showed that EPCs mainly existed at the edge of vascular wall, while SDF-1 could co-stain with alpha-smooth muscle actin (α-SMA) positive cells and CD31 positive cells. SDF-1 expression in brain AVM tissue was higher than that in control group. There were significant differences in the number of EPCs among the patients of different ages ( P<0.05). There was no significant difference in EPCs between cerebral hemorrhage group and non-hemorrhage group ( P>0.05). Brain AVM (<3 cm), single venous drainage and deep brain AVM are independent risk factors for cerebral AVM hemorrhage. In human brain AVM, EPC appears high level but decrease with age, which may play a role in vascular remodeling in AVM.

Endothelial MAP2K1 mutations in arteriovenous malformation activate the RAS/MAPK pathway

Arteriovenous malformation (AVM) is a locally destructive congenital vascular anomaly caused by somatic mutations in MAP2K1. The mutation is isolated to endothelial cells (ECs). The purpose of this study was to determine the effects of mutant MAP2K1 on EC signaling and vascular network formation. Pathway effects were studied using both mutant MAP2K1 (K57N) human AVM tissue and human umbilical vein endothelial cells (HUVECs) engineered to overexpress the MAP2K1 (K57N) mutation. Western blot was used to determine cell signaling along the RAS/MAPK pathway. Geltrex tube formation assays were performed to assess EC vascular network formation. Cells were treated with a MAP2K1 inhibitor (Trametinib) to determine its effect on signaling and vascular tube formation. Human mutant MAP2K1-AVM ECs had similar baseline MEK1 and ERK1/2 expression with controls; however, mutant MAP2K1-AVM ECs produced significantly more phosphorylated ERK1/2 than wild-type ECs. Mutant MAP2K1 HUVECs demonstrated significantly more phosphorylated ERK1/2 than control HUVECs. Trametinib reduced the phosphorylation of ERK1/2 in mutant cells and prevented the ability of ECs to form vascular networks. AVM MAP2K1 mutations activate RAS/MAPK signaling in ECs. ERK activation and vascular network formation are reduced with Trametinib. Pharmacotherapy using MAP2K1 inhibitors may prevent the formation or progression of AVMs.

Evaluation of digital image analysis as a supportive tool for the stratification of head and neck vascular anomalies

BackgroundThe histological differentiation of individual types of vascular anomalies (VA), such as lymphatic malformations (LM), hemangioma (Hem), paraganglioma (PG), venous malformations (VeM), arteriovenous malformations (AVM), pyogenic granulomas (GP), and (not otherwise classified) vascular malformations (VM n.o.c.) is frequently difficult due to the heterogeneity of these anomalies. The aim of the study was to evaluate digital image analysis as a method for VA stratificationMethodsA total of 40 VA tissues were examined immunohistologically using a selection of five vascular endothelial-associated markers (CD31, CD34, CLDN5, PDPN, VIM). The staining results were documented microscopically followed by digital image analyses based quantification of the candidate-marker-proteins using the open source program ImageJ/Fiji.ResultsDifferences in the expression patterns of the candidate proteins could be detected particularly when deploying the quotient of the quantified immunohistochemical signal values. Deploying signal marker quotients, LM could be fully distinguished from all other tested tissue types. GP achieved stratification from LM, Hem, VM, PG and AVM tissues, whereas Hem, PG, VM and AVM exhibited significantly different signal marker quotients compared with LM and GP tissues.ConclusionAlthough stratification of different VA from each other was only achieved in part with the markers used, the results of this study strongly support the usefulness of digital image analysis for the stratification of VA. Against the background of upcoming new diagnostic techniques involving artificial intelligence and deep (machine) learning, our data serve as a paradigm of how digital evaluation methods can be deployed to support diagnostic decision making in the field of VAs.

Vis-à-vis: a focus on genetic features of cerebral cavernous malformations and brain arteriovenous malformations pathogenesis

Cerebrovascular malformations include a wide range of blood vessel disorders affecting brain vasculature. Neuroimaging differential diagnosis can result unspecific due to similar phenotypes of lesions and their deep localization. Next-generation sequencing (NGS) platforms simultaneously analyze several hundreds of genes and can be applied for molecular distinction of different phenotypes within the same disorder's macro-area. We discuss about the main criticisms regarding molecular bases of cerebral cavernous malformations (CCM) and brain arteriovenous malformations (AVM), highlighting both common pathogenic aspects and genetic differences leading to lesion development. Many recent studies performed on human CCM and AVM tissues aim to detect genetic markers to better understand molecular bases and pathogenic mechanism, particularly for sporadic cases. Several genes involved in angiogenesis show different expression patterns between CCM and AVM, and these could represent a valid starting point to project a NGS panel to apply for differential cerebrovascular malformation diagnosis.

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.

Focal neurons: another source of vascular endothelial growth factor in brain arteriovenous malformation tissues?

BackgroundBrain arteriovenous malformations (bAVMs) are devastating, hemorrhage-prone, cerebrovascular entities characterized by well-defined feeding arteries, draining veins, and the absence of a capillary bed. The endothelial cells that comprise bAVMs exhibit a loss of arterial and venous specification. The role of abnormal angiogenesis in the formation and progression of bAVMs is still unclear. This study aimed to investigate the expression of vascular endothelial growth factor (VEGF) in neurons and glial cells in bAVMs to try to uncover the multiple cell origin of VEGF.MethodsA total of 25 bAVM specimens and 25 control tissues were obtained. Western blot and immunohistochemical analyses were used to evaluate the expression of VEGF. The distribution of VEGF in neurons and glial cells in these bAVMs were observed by double-label immunofluorescence staining and subsequent imaging.ResultsWestern blot analysis revealed a significant overexpression of VEGF in bAVM tissues (P < 0.05). Immunohistochemistry showed that the amount of cells that overexpressed VEGF in bAVM tissues was significantly greater compared to that in normal tissues (P < 0.05). Double-label immunofluorescence staining showed no significant difference between the mean amounts of VEGF-positive cells in astrocytes and in neurons (P < 0.05).ConclusionsThe formation and progression of bAVMs is related to the local overexpression of VEGF. Similar levels of VEGF overexpression are found in astrocytes, neurons, and vascular endothelial cells, which suggest that VEGF may be derived from astrocytes and neurons. It implied that focal neurons may play a certain role in the pathophysical process of bAVMs, however, identification of the production and functional mechanisms of VEGF in the neurons still requires further investigation.

Somatic MAP2K1 Mutations Are Associated with Extracranial Arteriovenous Malformation

Arteriovenous malformation (AVM) is a fast-flow, congenital vascular anomaly that may arise anywhere in the body. AVMs typically progress, causing destruction of surrounding tissue and, sometimes, cardiac overload. AVMs are difficult to control; they often re-expand after embolization or resection, and pharmacologic therapy is unavailable. We studied extracranial AVMs in order to identify their biological basis. We performed whole-exome sequencing (WES) and whole-genome sequencing (WGS) on AVM tissue from affected individuals. Endothelial cells were separated from non-endothelial cells by immune-affinity purification. We used droplet digital PCR (ddPCR) to confirm mutations found by WES and WGS, to determine whether mutant alleles were enriched in endothelial or non-endothelial cells, and to screen additional AVM specimens. In seven of ten specimens, WES and WGS detected and ddPCR confirmed somatic mutations in mitogen activated protein kinase kinase 1 (MAP2K1), the gene that encodes MAP-extracellular signal-regulated kinase 1 (MEK1). Mutant alleles were enriched in endothelial cells and were not present in blood or saliva. 9 of 15 additional AVM specimens contained mutant MAP2K1 alleles. Mutations were missense or small in-frame deletions that affect amino acid residues within or adjacent to the protein's negative regulatory domain. Several of these mutations have been found in cancers and shown to increase MEK1 activity. In summary, somatic mutations in MAP2K1 are a common cause of extracranial AVM. The likely mechanism is endothelial cell dysfunction due to increased MEK1 activity. MEK1 inhibitors, which are approved to treat several forms of cancer, are potential therapeutic agents for individuals with extracranial AVM.

Interplay between VEGF and Nrf2 regulates angiogenesis due to intracranial venous hypertension.

Venous hypertension(VH) plays an important role in the pathogenesis of cerebral arteriovenous malformations (AVMs) and is closely associated with the HIF-1α/VEGF signaling pathway. Nuclear factor erythroid 2-related factor 2(Nrf2) significantly influences angiogenesis; however, the interplay between Nrf2 and VEGF under VH in brain AVMs remains unclear. Therefore, our study aimed to investigate the interplay between Nrf2 and VEGF due to VH in brain AVMs. Immunohistochemistry indicated that Nrf2 and VEGF were highly expressed in human brain AVM tissues. In vivo, we established a VH model in both wild-type (WT) and siRNA-mediated Nrf2 knockdown rats. VH significantly increased the expression of Nrf2 and VEGF. Loss of Nrf2 markedly inhibited the upregulation of VEGF, as determined by Western blot analysis and qRT-PCR. In vitro, primary brain microvascular endothelial cells (BMECs) were isolated from WT and Nrf2−/− mice, and a VEGF-Nrf2 positive feed-back loop was observed in BMECs. By trans well assay and angiogenesis assay, Nrf2 knockout significantly inhibited the migration and vascular tube formation of BMECs. These findings suggest that the interplay between Nrf2 and VEGF can contribute to VH-induced angiogenesis in brain AVMs pathogenesis.

Differential expression of long no-coding RNA in human intracranial arteriovenous malformation tissue

Objective To investigate the differential expression of long no-coding RNA(LncRNA)in human brain arteriovenous malformation(AVM)tissue using an Arraystar-LncRNA chip. Methods The vascular nidi of 14 patients with AVM used as the specimens of the test group and operated in Beijing Tiantan Hospital, Capital Medical University were selected. The scalp blood vessel or superficial temporal artery segment of the same patient was used as a control specimen. Arraystar-LncRNA chip was used to conduct the expression profile analysis of LncRNA and mRNA. The maximum expression difference of 8 LncRNAs was selected for PCR validation. Results After screening and validation, in the 2 8012 detectable LncRNAs, 1 931 were up-regulated for ≥2 times and 450 were up-regulated for ≥4 times compared with the control group; 1 852 were down-regulated for ≥2 times and 719 were down-regulated for ≥4 times. In the 21 780 detectable mRNAs, 1 577 were up-regulated for ≥2 times, 450 were up-regulated for ≥4 times; and 1 699 were down-regulated for ≥2 times and 681 were down-regulated for ≥4 times. The bioinformatics and pathway analyses for mRNAs showed that the differential expression of 8-code mRNAs(FDXR, SYNE2, FCGR3A, NDUFS4, COX5A, OPA1, ETFA, and LPL)were most obvious in comparison of the test group and the control group. These mRNAs were associated with mitochondrial electron respiratory chain function, interaction between cytokines, stress response, lipoprotein lipase, and cytoskeleton associated protein. PCR validation for mRNAs associated with these LncRNAs showed that there were significant differences in the differential expression of 4 LncRNAs(codes ENS0423394(P=0.03), ENS0444114(P=0.01), TCONS_00013855(P=0.01), and ENS0452148(P=0.01). Conclusion The occurrence and development mechanism of intracranial AVM may be associated with the mitochondrial NADPH oxidoreductase, lipoprotein lipase, and optic atrophy associated protein-related down-regulation of LncRNA expression. Key words: Intracranial arteriovenous malformations; Gene expression profile; Biological processes; Long no-coding RNA

Elevated Expression of Matrix Metalloproteinase-9 not Matrix Metalloproteinase-2 Contributes to Progression of Extracranial Arteriovenous Malformation.

Extracranial arteriovenous malformations (AVMs) are rare but dangerous congenital lesions arising from direct arterial-venous shunts without intervening capillaries. Progressive infiltration, expansion, and soft tissue destruction lead to bleeding, pain, debilitation and disfigurement. The pathophysiology of AVMs is not well understood. Matrix Metalloproteinases (MMPs) are thought to play an important role in pathologic processes underlying many diseases. This study investigates the expression of MMP-9 and MMP-2 in aggressive extracranial AVMs. The differential expression of MMP-9 and its regulatory factors is also examined. Herein we demonstrate that mRNA and protein expressions of MMP-9, but not MMP-2, are significantly higher in AVM tissues compared to normal tissues. The serum level of MMP-9, but not MMP-2, is also elevated in AVM patients compared to healthy controls. MMP-9/neutrophil gelatinase-associated lipocalin (NGAL) complex is also significantly increased in AVM tissues. The MMP-9/ tissue inhibitor of metalloproteases-1 (TIMP-1) complex presents as a major form detected in normal tissues. The increased and aberrant expression of MMP-9 and specific MMP-9 forms may help explain the constitutive vascular remodeling and infiltrative nature of these lesions. Specific MMP-9 inhibitors would be a promising treatment for AVMs.

Abstract 192: Axonal Guidance Factors as Potential Pediatric AVM Urinary Biomarker

Introduction: Development of noninvasive biomarkers for pediatric arteriovenous malformations (AVMs) could improve diagnosis and identify potential therapeutic targets. The axonal guidance factor, EphrinB2, and its cognate receptor EphB4 have been implicated in AVM development. Here we report our initial experience with urinary EphrinB2 as a novel AVM-specific urinary biomarker. Hypothesis: We hypothesize that urinary and tissue levels of EphrinB2 will be elevated in patients with AVM and distinguish AVM from other cerebrovascular disease. Methods: Specimens were collected from 45 pediatric patients (0-21 years of age) including unruptured AVM (n=15), moyamoya (n=15) and age- and sex-matched controls (n=15), per an IRB-approved protocol. ELISA quantified levels of urinary EphrinB2. Matched AVM tissue from the same patient was subjected to immunohistochemistry to correlate source tissue expression with biomarker levels. Results: Statistical analysis revealed a statistically significant increase in EphrinB2 and AVM-specific biomarker fingerprints capable of discerning AVM both from controls and also from other types of vascular neurosurgical disease. Compared to controls, EphrinB2 was elevated with mean EphrinB2 (0.10 pg/ug vs. 0.019 pg/ug, p&lt;0.01) and compared to moyamoya patients mean EphrinB2 (0.10 pg/ug vs. 0.014, p&lt;0.01). Similarly, EphrinB2 and EphB4 staining was significantly increased in AVM tissue vs. normal blood vessels matched as controls. Conclusion: In conclusion, these data suggests potential utility of urinary biomarkers, specifically EphrinB2, as diagnostic tools for clinicians treating children with AVMs and demonstrates proof-of- principle results supporting the concept of hypothesis-driven biomarker “fingerprinting” for unique cerebrovascular disease, differentiating AVM from other vascular pathology. For the first time, these data correlate known aspects of AVM molecular biology with clinically relevant diagnostics.