Synthetic VSMCs induce BBB disruption mediated by MYPT1 in ischemic stroke.
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ABSTRACT:
SUBMITTER: Meng H
PROVIDER: S-EPMC8441154 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Roles of reactive perivascular astrocytes in dysregulation of the blood-brain barrier (BBB) function and cerebral perfusion are not well defined. Here, we investigated transformation of reactive astrocyte function for vascular repair after ischemic stroke by targeted deletion of astrocytic Na+/H+ exchanger isoform 1 in Gfap-CreERT2+/-;Nhe1f/f (Nhe1 Astro-KO) mice. Control Gfap-CreERT2+/-;Nhe1f/f (wild-type) mice displayed BBB damage (elevated endothelial transcytosis and intracellular vesicles) and persistent cerebral hypoperfusion in an ischemic stroke model (transient middle cerebral artery occlusion). In contrast, Nhe1 Astro-KO mice exhibited significantly less endothelial transcytosis and vesicle formation, and increased angiogenesis and cerebral blood perfusion (CBF) post-stroke. Bulk RNA-sequencing transcriptome analysis of isolated GFAP+ reactive astrocytes from wild-type and Nhe1 Astro-KO ischemic brains revealed that ~177 genes were differentially upregulated, with the Wnt7a mRNA among the top upregulated genes, along with additional Wnt pathway genes (Wnt7b, Fzd9, Fzd10, and Ndp). Abundant Wnt7a/b and β-catenin protein expression was detected in cerebral vessels of Nhe1 Astro-KO ischemic brains but not in the wild-type brains. Selective activation of Wnt/β-catenin pathway in cerebral vessels of Nhe1 Astro-KO ischemic brains was further validated using the Wnt reporter line TCF/LEF::H2B-eGFP; Gfap-CreERT2+/-;Nhe1f/f mice. Lastly, the role of Wnt/β-catenin pathway in resistance of Nhe1 Astro-KO mice to stroke-mediated BBB damage was tested by administration of Wnt/β-catenin inhibitor XAV-939. Taken together, we report that transforming reactive astrocyte function by upregulating astrocytic Wnt/β-catenin signaling activity is a novel mechanism to reduce the BBB endothelial damage, stimulate vascular repair, and restore cerebral blood flow after ischemic stroke.
2020-12-08 | GSE145839 | GEO
Project description:Stroke is a leading cause of morbidity and mortality globally. Leonurine (also named SCM-198), a compound extracted from Herba leonuri, was effective on the prevention of various cardiovascular and brain diseases. The purpose of this study was to explore the possible therapeutic potential of SCM-198 against ischemia reperfusion injury and underlying mechanisms. In the in vivo transient middle cerebral artery occlusion (tMCAO) rat model, we found that treatment with SCM-198 could decrease infarct volume and improve neurological deficit by protecting against blood-brain barrier (BBB) breakdown. In the in vitro model of cell oxygen-glucose deprivation and reoxygenation (OGD/R), consistent results were obtained with decreased reactive oxygen species (ROS) production and maintained the BBB integrity. Further study demonstrated that SCM-198 increased the expression of histone deacetylase- (HDAC-) 4 which could inhibit NADPH oxidase- (NOX-) 4 and matrix metalloproteinase- (MMP-) 9 expression, resulting in the elevation of tight junction proteins, including claudin-5, occludin, and zonula occluden- (ZO-) 1. These results indicated SCM-198 protected BBB integrity by regulating the HDAC4/NOX4/MMP-9 tight junction pathway. Our findings provided novel insights into the protective effects and mechanisms of SCM-198 on ischemic stroke, indicating SCM-198 as a new class of potential drug against acute onset of ischemic stroke.
| S-EPMC5485366 | biostudies-literature
Project description:Hypoxia-induced disruption of the blood-brain barrier (BBB) is the result of many different mechanisms, including alterations to the cytoskeleton. In this study, we identified actin-binding proteins involved in cytoskeletal dynamics with quantitative proteomics and assessed changes in subcellular localization of two proteins involved in actin polymerization [vasodilator-stimulated phosphoprotein (VASP)] and cytoskeleton-plasma membrane cross-linking (moesin). We found significant redistribution of both VASP and moesin to the cytoskeletal and membrane fractions of BBB endothelial cells after 1-h hypoxic stress. We also investigated activation of actin-myosin contraction through assessment of phosphorylated myosin light chain (pMLC) with confocal microscopy. Hypoxia caused a rapid and transient increase in pMLC. Blocking MLC phosphorylation through inhibition of myosin light chain kinase (MLCK) with ML-7 prevented hypoxia-induced BBB disruption and relocalization of the tight junction protein ZO-1. Finally, we implicate the transient receptor potential (TRP)C family of channels in mediating these events since blockade of TRPC channels and the associated calcium influx with SKF-96365 prevents hypoxia-induced permeability changes and the phosphorylation of MLC needed for actin-myosin contraction. These data suggest that hypoxic stress triggers alterations to cytoskeletal structure that contribute to BBB disruption and that calcium influx through TRPC channels contributes to these events.
| S-EPMC2889642 | biostudies-literature
Project description:ObjectivesTo report and associate acute cerebral infarctions in 2 young, previously healthy siblings with use of the street drug known as "spice" (a synthetic marijuana product, also known as "K2"), which they independently smoked before experiencing acute embolic-appearing ischemic strokes.MethodsWe present history, physical examination, laboratory data, cerebrovascular imaging, echocardiogram, ECG, and hospital course of these patients.ResultsWe found that in both siblings spice was obtained from the same source. The drug was found to contain the schedule I synthetic cannabinoid JWH-018. Full stroke workup was unrevealing of a stroke etiology; urine drug screen was positive for marijuana.ConclusionsWe found that our 2 patients who smoked the street drug spice had a temporal association with symptoms of acute cerebral infarction. This association may be confounded by contaminants in the product consumed (i.e., marijuana or an unidentified toxin) or by an unknown genetic mechanism. The imaging of both patients suggests an embolic etiology, which is consistent with reports of serious adverse cardiac events with spice use, including tachyarrhythmias and myocardial infarctions.
| S-EPMC3863350 | biostudies-literature
Project description:BackgroundNeuroinflammation, which is mainly mediated by excessive microglia activation, plays a major role in ischemic stroke. Overactivated microglia secrete numerous inflammatory cytokines, causing excessive inflammatory responses and ultimately exacerbating ischemic brain injury. Hence, compounds that attenuate neuroinflammation could become promising drug candidates for ischemic stroke. Fraxetin has an anti-inflammatory effect in many inflammatory diseases. However, whether it possesses an anti-inflammatory capacity in microglia-mediated neuroinflammation after ischemic brain injury is unknown. Our study aimed to investigate the suppression effect of fraxetin on neuroinflammation in lipopolysaccharide (LPS)-activated microglia and establish whether fraxetin could alleviate ischemic brain injury in a rodent model of ischemic stroke.MethodsFor the in vitro experiment, primary microglia were obtained from 1-day-old C57/BL6J mice. The cells were activated with LPS and treated with fraxetin at a non-cytotoxic concentration. Real-time PCR, enzyme-linked immunosorbent assays, and immunofluorescence staining were used to evaluate the anti-inflammatory effects of fraxetin. The potential molecular mechanisms were explored and verified through RNA-sequencing analysis, western blotting and real-time PCR. For the in vivo experiment, focal ischemia was induced by middle cerebral artery occlusion (MCAO) in 8-week-old male C57/BL6J mice. Fraxetin (5 mg/kg) or an equal volume of saline was injected into mice intraperitoneally after MCAO, and 2% 2,3,5-triphenyltetrazolium chloride staining was applied to measure infarct volume. Behavioral tests were conducted to measure neurological deficits in the mice. Real-time PCR, western blotting, and immunofluorescence staining were used to examine the expression of inflammatory cytokines and microglia activation in the ischemic penumbra.ResultsFraxetin effectively inhibited the expression of proinflammatory cytokines including inducible nitric oxide synthase, tumor necrosis factor-α, interleukin-1 beta, and interleukin-6 in LPS-activated microglia. Fraxetin also suppressed the PI3K/Akt/NF-κB signaling pathway in activated microglia, which contributed to its anti-inflammatory effects. Furthermore, the administration of fraxetin attenuated ischemic brain injury and behavioral deficits after stroke. Finally, fraxetin was found to attenuate the activation of microglia both in vitro and in vivo.ConclusionsOur results suggest that fraxetin has a suppression effect on microglia-mediated neuroinflammation, and this effect is associated with the PI3K/Akt/NF-κB signaling pathway. Fraxetin may therefore have potential neuroprotective properties for ischemic stroke.
| S-EPMC9096375 | biostudies-literature
Project description:The Network Modification (NeMo) Tool uses a library of brain connectivity maps from normal subjects to quantify the amount of structural connectivity loss caused by focal brain lesions. We hypothesized that the Network Modification Tool could predict remote brain tissue loss caused by poststroke loss of connectivity.Baseline and follow-up MRIs (10.7±7.5 months apart) from 26 patients with acute ischemic stroke (age, 74.6±14.1 years, initial National Institutes of Health Stroke Scale, 3.1±3.1) were collected. Lesion masks derived from diffusion-weighted images were superimposed on the Network Modification Tool's connectivity maps, and regional structural connectivity losses were estimated via the Change in Connectivity (ChaCo) score (ie, the percentage of tracks connecting to a given region that pass through the lesion mask). ChaCo scores were correlated with subsequent atrophy.Stroke lesions' size and location varied, but they were more frequent in the left hemisphere. ChaCo scores, generally higher in regions near stroke lesions, reflected this lateralization and heterogeneity. ChaCo scores were highest in the postcentral and precentral gyri, insula, middle cingulate, thalami, putamen, caudate nuclei, and pallidum. Moderate, significant partial correlations were found between baseline ChaCo scores and measures of subsequent tissue loss (r=0.43, P=4.6×10(-9); r=0.61, P=1.4×10(-18)), correcting for the time between scans.ChaCo scores varied, but the most affected regions included those with sensorimotor, perception, learning, and memory functions. Correlations between baseline ChaCo and subsequent tissue loss suggest that the Network Modification Tool could be used to identify regions most susceptible to remote degeneration from acute infarcts.
| S-EPMC3943489 | biostudies-literature
Project description:Stimulation of Na+ /H+ exchanger isoform 1 (NHE1) in astrocytes causes ionic dysregulation under ischemic conditions. In this study, we created a Nhe1flox/flox (Nhe1f/f ) mouse line with exon 5 of Nhe1 flanked with two loxP sites and selective ablation of Nhe1 in astrocytes was achieved by crossing Nhe1f/f mice with Gfap-CreERT2 Cre-recombinase mice. Gfap-CreERT2+/- ;Nhe1f/f mice at postnatal day 60-90 were treated with either corn oil or tamoxifen (Tam, 75 mg/kg/day, i.p.) for 5 days. After 30 days post-injection, mice underwent transient middle cerebral artery occlusion (tMCAO) to induce ischemic stroke. Compared with the oil-vehicle group (control), Tam-treated Gfap-CreERT2+/- ;Nhe1f/f (Nhe1 KO) mice developed significantly smaller ischemic infarction, less edema, and less neurological function deficits at 1-5 days after tMCAO. Immunocytochemical analysis revealed less astrocytic proliferation, less cellular hypertrophy, and less peri-lesion gliosis in Nhe1 KO mouse brains. Selective deletion of Nhe1 in astrocytes also reduced cerebral microvessel damage and blood-brain barrier (BBB) injury in ischemic brains. The BBB microvessels of the control brains show swollen endothelial cells, opened tight junctions, increased expression of proinflammatory protease MMP-9, and significant loss of tight junction protein occludin. In contrast, the Nhe1 KO mice exhibited reduced BBB breakdown and normal tight junction structure, with increased expression of occludin and reduced MMP-9. Most importantly, deletion of astrocytic Nhe1 gene significantly increased regional cerebral blood flow in the ischemic hemisphere at 24 hr post-MCAO. Taken together, our study provides the first line of evidence for a causative role of astrocytic NHE1 protein in reactive astrogliosis and ischemic neurovascular damage.
| S-EPMC5705024 | biostudies-literature
Project description:Infiltration of peripheral immune cells after blood-brain barrier (BBB) dysfunction causes severe inflammation after a stroke. Although the endothelial glycocalyx functions as a barrier to circulating cells, the relationship between stroke severity and glycocalyx dysfunction remains unclear. In this study, glycosaminoglycans (GAGs), a component of the endothelial glycocalyx, in ischemic stroke were studied using a photochemically induced thrombosis (PIT) mouse model. As results, decreased levels of heparan sulfate (HS) and chondroitin sulfate (CS) and increased activity of hyaluronidase 1 and heparanase (HPSE) were observed in ischemic brain tissues. HPSE expression in cerebral vessels increased after stroke onset and infarct volume greatly decreased after co-administration of N-acetylcysteine (NAC)+GAG oligosaccharides as compared to NAC administration alone. These results suggest that the endothelial glycocalyx was injured after the onset of stroke. Interestingly, scission activity of proHPSE produced by HBMEC/ciβ and HEK293 cells transfected with hHPSE1 cDNA were activated by acrolein exposure. We identified the ACR modified amino acid residues of proHPSE using nano LC-MS/MS, suggesting that ACR modification of Lys139 (6-kDa linker), and Lys107 and Lys161, located in the immediate vicinity of the 6-kDa linker, at least in part, is attributed to the activation of proHPSE. Since proHPSE, but not HPSE, localizes outside cells by binding with HS proteoglycans, ACR-modified proHPSE represents a promising target to protect the endothelial glycocalyx.
2020-11-16 | PXD021040 | Pride
Project description:Using a hitherto uncharacterized knockout mouse model of Notch 3, a Notch signaling receptor paralogue highly expressed in vascular SMCs, we uncover a striking susceptibility to ischemic stroke upon challenge. Cellular and molecular analyses of vascular SMCs derived from these animals associate Notch 3 activity to the expression of specific gene targets, whereas genetic rescue experiments unambiguously link Notch 3 function in vessels to the ischemic phenotype. Microarray Studies. Biotinylated cRNA samples from freshly sorted brain SMCs (four Notch 3 +/- mice and five Notch 3 -/- mice) were fragmented before hybridization (15 ug each) onto mouse 430 2.0 Affymetrix chips. The chips were washed, stained by using strepavidin-phycoerytrin, and scanned the next day as described in ref. 24. For data normalization, all probe sets were scaled to a target intensity of 150. Microarray data analysis was performed by using Rosetta Resolver. All cells were from 10- to 12-week-old male mice. Gene Ontology Analyses. PANTHER software was used to define over- and underrepresented functions in the list of signature genes found by microarray analysis (25). P values were calculated by using binomial statistics.
2014-06-11 | E-GEOD-58368 | biostudies-arrayexpress
Project description:BACKGROUND:The blood-brain barrier (BBB) maintains homeostasis of the brain environment by tightly regulating the entry of substances from systemic circulation. A breach in the BBB results in increased permeability to potentially toxic substances and is an important contributor to amplification of ischemic brain damage. The precise molecular pathways that result in impairment of BBB integrity remain to be elucidated. Autophagy is a degradation pathway that clears damaged or unnecessary proteins from cells. However, excessive autophagy can lead to cellular dysfunction and death under pathological conditions. METHODS:In this study, we investigated whether autophagy is involved in BBB disruption in ischemia, using in vitro cells and in vivo rat models. We used brain endothelial bEnd.3 cells and oxygen glucose deprivation (OGD) to simulate ischemia in culture, along with a rat ischemic stroke model to evaluate the role of autophagy in BBB disruption during cerebral ischemia. RESULTS:OGD 18 h induced cellular dysfunction, and increased permeability with degradation of occludin and activation of autophagy pathways in brain endothelial cells. Immunostaining revealed that occludin degradation is co-localized with ischemic autophagosomes. OGD-induced occludin degradation and permeability changes were significantly decreased by inhibition of autophagy using 3-methyladenine (3-MA). Enhanced autophagic activity and loss of occludin were also observed in brain capillaries isolated from rats with middle cerebral artery occlusion (MCAO). Intravenous administration of 3-MA inhibited these molecular changes in brain capillaries, and recovered the increased permeability as determined using Evans blue. CONCLUSIONS:Our findings provide evidence that autophagy plays an important role in ischemia-induced occludin degradation and loss of BBB integrity.
| S-EPMC7071658 | biostudies-literature