Mouse Brain Microvascular Endothelial Cells Research Articles

Junctional adhesion molecule-A deficient mice are protected from severe experimental autoimmune encephalomyelitis.

In multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis (EAE), early pathological features include immune cell infiltration into the central nervous system (CNS) and blood-brain barrier (BBB) disruption. We investigated the role of junctional adhesion molecule-A (JAM-A), a tight junction protein, in active EAE (aEAE) pathogenesis. Our study confirms JAM-A expression at the blood-brain barrier and its luminal redistribution during aEAE. JAM-A deficient (JAM-A-/-) C57BL/6J mice exhibited milder aEAE, unrelated to myelin oligodendrocyte glycoprotein-specific CD4+ T-cell priming. While JAM-A absence influenced macrophage behavior on primary mouse brain microvascular endothelial cells (pMBMECs) under flow in vitro, it did not impact T-cell extravasation across primary mouse brain microvascular endothelial cells. At aEAE onset, we observed reduced lymphocyte and CCR2+ macrophage infiltration into the spinal cord of JAM-A-/- mice compared to control littermates. This correlated with increased CD3+ T-cell accumulation in spinal cord perivascular spaces and brain leptomeninges, suggesting JAM-A absence leads to T-cell trapping in central nervous system border compartments. In summary, JAM-A plays a role in immune cell infiltration and clinical disease progression in aEAE.

Long noncoding RNA KCNQ1OT1 aggravates cerebral infarction by regulating PTBT1/SIRT1 via miR-16-5p.

Cerebral infarction (CI) is one of the leading causes of disability and death. LncRNAs are key factors in CI progression. Herein, we studied the function of long noncoding RNA KCNQ1OT1 in CI patient plasma samples and in CI models. Quantitative real-time PCR and Western blotting tested gene and protein expressions. The interactions of KCNQ1OT1/PTBP1 and miR-16-5p were analyzed using dual-luciferase reporter and RNA immunoprecipitation assays; MTT assays measured cell viability. Cell migration and angiogenesis were tested by wound healing and tube formation assays. Pathological changes were analyzed by triphenyltetrazolium chloride and routine staining. We found that KCNQ1OT1 and PTBP1 were overexpressed and miR-16-5p was downregulated in CI patient plasma and in oxygen-glucose deprived (OGD) induced mouse brain microvascular endothelial (bEnd.3) cells. KCNQ1OT1 knockdown suppressed pro-inflammatory cytokine production and stimulated angiogenic responses in OGD-bEnd.3 cells. KCNQ1OT1 upregulated PTBP1 by sponging miR-16-5p. PTBP1 overexpression or miR-16-5p inhibition attenuated the effects of KCNQ1OT1 knockdown. PTBP1 silencing protected against OGD-bEnd.3 cell injury by enhancing SIRT1. KCNQ1OT1 silencing or miR-16-5p overexpression also alleviated ischemic injury in a mice middle cerebral artery occlusion model. Thus, KCNQ1OT1 silencing alleviates CI by regulating the miR-16-5p/PTBP1/SIRT1 pathway, providing a theoretical basis for novel therapeutic strategies targeting CI.

Interleukin-22 Contributes to Blood-Brain Barrier Disruption via STAT3/VEGFA Activation in Escherichia coli Meningitis.

Escherichia coli continues to be the predominant Gram-negative pathogen causing neonatal meningitis worldwide. Inflammatory mediators have been implicated in the pathogenesis of meningitis and are key therapeutic targets. The role of interleukin-22 (IL-22) in various diseases is diverse, with both protective and pathogenic effects. However, little is understood about the mechanisms underlying the damaging effects of IL-22 on the blood-brain barrier (BBB) in E. coli meningitis. We observed that meningitic E. coli infection induced IL-22 expression in the serum and brain of mice. The tight junction proteins (TJPs) components ZO-1, Occludin, and Claudin-5 were degraded in the mouse brain and human brain microvascular endothelial cells (hBMEC) following IL-22 administration. Moreover, the meningitic E. coli-caused increase in BBB permeability in wild-type mice was restored by knocking out IL-22. Mechanistically, IL-22 activated the STAT3-VEGFA signaling cascade in E. coli meningitis, thus eliciting the degradation of TJPs to induce BBB disruption. Our data indicated that IL-22 is an essential host accomplice during E. coli-caused BBB disruption and could be targeted for the therapy of bacterial meningitis.

Abstract TP314: The α5 Integrin Inhibitor ATN161 Mitigates SARS-CoV-2- Induced Brain Endothelial Barrier Disruption and Neuroinflammation α5 Integrin Inhibitor ATN 161

Introduction: Although SARS-CoV-2 infection can cause a wide range of mild to severe symptoms, the pathophysiology of acute and long-term neurological manifestations remains elusive. The arginine-glycine-aspartic acid motif of the viral spike protein may use to bind integrins receptors in the CNS, which play an important role in cerebrovascular integrity. Here we investigate the role of integrin α5β1 in mediating brain endothelial damage and inflammation during SARS-CoV-2 infection. Method: Mouse brain microvascular endothelial cells (bEnd.3) were treated with SARS-CoV-2 (Isolate USA-WA1/2020) or delta variant spike protein for 24h then later exposed to hypoxia for 6h (to model the effects of in vivo pulmonary infection). Cells were pretreated with ATN-16, 1h before SARS-CoV-2 and hypoxia challenge. Further, BALB/c mice were inoculated intranasally with 2x10 4 -PFU of the MA-10 strain of SARS-CoV-2 and treated with 1mg/kg of ATN-161, an α5β1 integrin inhibitor, retro-orbitally. The brains were collected 3 days post-infection for neuropathological evaluation. Results: SARS-CoV-2 and delta variant spike protein inoculations induced integrin α5 and decreased claudin-5 expression in bEnd.3 cells in a dose-dependent manner. SARS-CoV-2 spike protein challenge at 0.5 μg for 24h followed by hypoxia for 6h resulted in increased α5 and decreased claudin-5 expression in either hypoxia or SARS-CoV-2+hypoxia combination. ATN-161 (10μM) pretreatment inhibited SARS-CoV-2+hypoxia-induced α5 upregulation and restored claudin-5 loss in bEnd.3 cells. The in vivo studies showed a significant increase in the pro-inflammatory response as measured by cytokine IL-6 expression and a decrease in barrier integrity by tight junction claudin-5 expression in the brains of MA10-infected mice compared to mock controls. ATN-161 treatment decreased IL-6 expression and increased claudin 5 expression in infected mice. Conclusion: Therefore, we propose that targeting integrin α5β1 through inhibitors such as ATN-161 offers a promising therapeutic strategy for attenuating SARS-CoV-2 and its immunological impact on brain vasculature. This approach may be pivotal in reducing both acute and chronic neurological morbidities associated with COVID-19.

Protective Effects of Sophoraflavanone G by Inhibiting TNF-α-Induced MMP-9-Mediated Events in Brain Microvascular Endothelial Cells.

The regulation of matrix metalloproteinases (MMPs), especially MMP-9, has a critical role in both physiological and pathological events in the central nervous system (CNS). MMP-9 is an indicator of inflammation that triggers several CNS disorders, including neurodegeneration. Tumor necrosis factor-α (TNF-α) has the ability to stimulate the production of different inflammatory factors, including MMP-9, in several conditions. Numerous phytochemicals are hypothesized to mitigate inflammation, including the CNS. Among them, a flavonoid compound, sophoraflavanone G (SG), found in Sophora flavescens has been found to possess several medicinal properties, including anti-bacterial and anti-inflammatory effects. In this study, mouse brain microvascular endothelial cells (bMECs) were used to explore TNF-α-induced MMP-9 signaling. The effects of SG on TNF-α-induced MMP-9 expression and its mechanisms were further evaluated. Our study revealed that the expression of MMP-9 in bMECs was stimulated by TNF-α through the activation of ERK1/2, p38 MAPK, and JNK1/2 via the TNF receptor (TNFR) with a connection to the NF-κB signaling pathway. Moreover, we found that SG can interact with the TNFR. The upregulation of MMP-9 by TNF-α may lead to the disruption of zonula occludens-1 (ZO-1), which can be mitigated by SG administration. These findings provide evidence that SG may possess neuroprotective properties by inhibiting the signaling pathways associated with TNFR-mediated MMP-9 expression and the subsequent disruption of tight junctions in brain microvascular endothelial cells.

A20 regulates lymphocyte adhesion in murine neuroinflammation by restricting endothelial ICOSL expression in the CNS.

A20 is a ubiquitin-modifying protein that negatively regulates NF-κB signaling. Mutations in A20/TNFAIP3 are associated with a variety of autoimmune diseases, including multiple sclerosis (MS). We found that deletion of A20 in central nervous system (CNS) endothelial cells (ECs) enhances experimental autoimmune encephalomyelitis (EAE), a mouse model of MS. A20ΔCNS-EC mice showed increased numbers of CNS-infiltrating immune cells during neuroinflammation and in the steady state. While the integrity of the blood-brain barrier (BBB) was not impaired, we observed a strong activation of CNS-ECs in these mice, with dramatically increased levels of the adhesion molecules ICAM-1 and VCAM-1. We discovered ICOSL to be expressed by A20-deficient CNS-ECs, which we found to function as adhesion molecules. Silencing of ICOSL in CNS microvascular ECs partly reversed the phenotype of A20ΔCNS-EC mice without reaching statistical significance and delayed the onset of EAE symptoms in WT mice. In addition, blocking of ICOSL on primary mouse brain microvascular ECs impaired the adhesion of T cells in vitro. Taken together, we propose that CNS EC-ICOSL contributes to the firm adhesion of T cells to the BBB, promoting their entry into the CNS and eventually driving neuroinflammation.

TMIC-08. CLAUDIN-1 UPREGULATION IN GLIOBLASTOMA INDUCED BLOOD-BRAIN-BARRIER DYSFUNCTION VIA A PARACRINE MECHANISM

Abstract BACKGROUND Blood-brain-barrier (BBB) disruption is a well-known phenomenon in glioblastoma. However, the mechanism driving BBB dysfunction in GBM is still unknown, especially in the previously established vasculature near the invasive edge. In this study, we aimed to determine if GBM paracrine signaling is sufficient to induce BBB dysfunction and identify changes in the tight junctions of the BBB. METHODS An in vivo xenograft model was established through an intracranial injection of U-87 MG cells in nude mice. Weekly MRIs were performed to monitor tumor growth. Two weeks after tumor appearance, brains were collected following a 4% PFA perfusion for immunostaining and confocal imaging. An in vitro model of the BBB was created by seeding primary mouse brain microvascular endothelial cells (BMECs) on transwell inserts. Once the BMECs reached confluency with a TEER value of 170-175Ω*cm2, the media was replaced with filtered conditioned media from U-87 MG cell line, an IDH mutant cell line, or BMECs for three days with TEER values monitored each day. RESULTS Immunofluorescent staining revealed a significant increase in claudin-1 expression and decrease in claudin-5 expression in the tumor vs normal brain tissue of our in vivo model (p < 0.01). After 24 hours of exposure to conditioned media from both U-87 MG and IDH mutant cells, BMECs had a significant decrease in TEER compared to control and BMEC conditioned media (p < .0001). After 72 hours, TEER values continued to decrease, reaching around 155Ω*cm2, with control BMECs remaining around 187Ω*cm2. CONCLUSIONS These results suggest GBM cells secrete factors capable of inducing changes in the tight junction proteins of the BBB and increasing its permeability. Future studies will aim to identify the mechanism in which these changes occur.

Compromised Blood-Brain Barrier Junctions Enhance Melanoma Cell Intercalation and Extravasation.

Melanoma frequently metastasises to the brain, and a detailed understanding of the molecular and cellular mechanisms underlying melanoma cell extravasation across the blood-brain barrier (BBB) is important for preventing brain metastasis formation. Making use of primary mouse brain microvascular endothelial cells (pMBMECs) as an in vitro BBB model, we imaged the interaction of melanoma cells into pMBMEC monolayers. We observed exclusive junctional intercalation of melanoma cells and confirmed that melanoma-induced pMBMEC barrier disruption can be rescued by protease inhibition. Interleukin (IL)-1β stimulated pMBMECs or PECAM-1-knockout (-ko) pMBMECs were employed to model compromised BBB barrier properties in vitro and to determine increased melanoma cell intercalation compared to pMBMECs with intact junctions. The newly generated brain-homing melanoma cell line YUMM1.1-BrM4 was used to reveal increased in vivo extravasation of melanoma cells across the BBB of barrier-compromised PECAM-1-deficient mice compared to controls. Taken together, our data indicate that preserving BBB integrity is an important measure to limit the formation of melanoma-brain metastasis.

Cerebral Microvascular Injury Induced by Lag3-Dependent α-Synuclein Fibril Endocytosis Exacerbates Cognitive Impairment in a Mouse Model of α-Synucleinopathies.

The pathological accumulation of α-synuclein (α-Syn) and the transmission of misfolded α-Syn underlie α-synucleinopathies. Increased plasma α-Syn levels are associated with cognitive impairment in Parkinson's disease, multiple system atrophy, and dementia with Lewy bodies, but it is still unknown whether the cognitive deficits in α-synucleinopathies have a common vascular pathological origin. Here, it is reported that combined injection of α-Syn preformed fibrils (PFFs) in the unilateral substantia nigra pars compacta, hippocampus, and cerebral cortex results in impaired spatial learning and memory abilities at 6 months post-injection and that this cognitive decline is related to cerebral microvascular injury. Moreover, insoluble α-Syn inclusions are found to form in primary mouse brain microvascular endothelial cells (BMVECs) through lymphocyte-activation gene 3 (Lag3)-dependent α-Syn PFFs endocytosis, causing poly(ADP-ribose)-driven cell death and reducing the expression of tight junction proteins in BMVECs. Knockout of Lag3 in vitro prevents α-Syn PFFs from entering BMVECs, thereby reducing the abovementioned response induced by α-Syn PFFs. Deletion of endothelial cell-specific Lag3 in vivo reverses the negative effects of α-Syn PFFs on cerebral microvessels and cognitive function. In short, this study reveals the effectiveness of targeting Lag3 to block the spread of α-Syn fibrils to endothelial cells in order to improve cognition.

Construction and optimization of a coculture system of mouse brain microvascular endothelial cells and myelin debris

Microvascular endothelial cells are a newly discovered cell type involved in the phagocytosis of myelin debris, which play a key role in the repair of spinal cord injuries. Several methods for the preparation of myelin debris and parameters for constructing a coculture system of microvascular endothelial cells and myelin debris are available, but no systematic studies have yet been conducted, which hinders further exploration of the mechanisms of demyelinating disease repair. Herein, we aimed to develop a standardized method for this process. Myelin debris of different sizes was obtained from the brains of C57BL/6 mice by stripping the brains under aseptic conditions, multiple grinding, gradient centrifugation, etc. Transmission electron microscopy and nanoparticle size analysis were used to characterize myelin debris. Microvascular endothelial cells were cultured on a matrix gel, and myelin debris of different sizes (fluorescently labeled using CFSE) was placed in coculture after forming a vascular-like structure. Subsequently, myelin debris of different concentrations was cocultured in the vascular-like structure, and phagocytosis of myelin debris by microvascular endothelial cells was detected using immunofluorescence staining and flow cytometry. We found that myelin debris could be successfuly obtained from the mouse brain with secondary grinding and other steps and cocultured with microvascular endothelial cells at a concentration of 2 mg/mL, which promoted the phagocytosis of microvascular endothelial cells. In conclusion, we provide a reference for the protocol of a coculture system of microvascular endothelial cells and myelin debris.

Lung infection by Pseudomonas aeruginosa induces neuroinflammation and blood–brain barrier dysfunction in mice

BackgroundSevere lung infection can lead to brain dysfunction and neurobehavioral disorders. The mechanisms that regulate the lung-brain axis of inflammatory response to respiratory infection are incompletely understood. This study examined the effects of lung infection causing systemic and neuroinflammation as a potential mechanism contributing to blood–brain barrier (BBB) leakage and behavioral impairment.MethodsLung infection in mice was induced by instilling Pseudomonas aeruginosa (PA) intratracheally. We determined bacterial colonization in tissue, microvascular leakage, expression of cytokines and leukocyte infiltration into the brain.ResultsLung infection caused alveolar-capillary barrier injury as indicated by leakage of plasma proteins across pulmonary microvessels and histopathological characteristics of pulmonary edema (alveolar wall thickening, microvessel congestion, and neutrophil infiltration). PA also caused significant BBB dysfunction characterized by leakage of different sized molecules across cerebral microvessels and a decreased expression of cell–cell junctions (VE-cadherin, claudin-5) in the brain. BBB leakage peaked at 24 h and lasted for 7 days post-inoculation. Additionally, mice with lung infection displayed hyperlocomotion and anxiety-like behaviors. To test whether cerebral dysfunction was caused by PA directly or indirectly, we measured bacterial load in multiple organs. While PA loads were detected in the lungs up to 7 days post-inoculation, bacteria were not detected in the brain as evidenced by negative cerebral spinal fluid (CSF) cultures and lack of distribution in different brain regions or isolated cerebral microvessels. However, mice with PA lung infection demonstrated increased mRNA expression in the brain of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α), chemokines (CXCL-1, CXCL-2) and adhesion molecules (VCAM-1 and ICAM-1) along with CD11b + CD45+ cell recruitment, corresponding to their increased blood levels of white cells (polymorphonuclear cells) and cytokines. To confirm the direct effect of cytokines on endothelial permeability, we measured cell–cell adhesive barrier resistance and junction morphology in mouse brain microvascular endothelial cell monolayers, where administration of IL-1β induced a significant reduction of barrier function coupled with tight junction (TJ) and adherens junction (AJ) diffusion and disorganization. Combined treatment with IL-1β and TNFα augmented the barrier injury.ConclusionsLung bacterial infection is associated with BBB disruption and behavioral changes, which are mediated by systemic cytokine release.

Helicobacter pylori infection selectively attenuates endothelial function in male mice via exosomes-mediated ROS production.

Substantial sex differences exist in atherosclerosis. Excessive reactive oxygen species (ROS) formation could lead to endothelial dysfunction which is critical to atherosclerosis development and progression. Helicobacter pylori (H. pylori) infection has been shown to attenuate endothelial function via exosomes-mediated ROS formation. We have demonstrated that H. pylori infection selectively increases atherosclerosis risk in males with unknown mechanism(s). The present study was to test the hypothesis that H. pylori infection impaired endothelial function selectively in male mice through exosome-mediated ROS formation. Age-matched male and female C57BL/6 mice were infected with CagA+ H. pylori to investigate sex differences in H. pylori infection-induced endothelial dysfunction. H. pylori infection attenuated acetylcholine (ACh)-induced endothelium-dependent aortic relaxation without changing nitroglycerine-induced endothelium-independent relaxation in male but not female mice, associated with increased ROS formation in aorta compared with controls, which could be reversed by N-acetylcysteine treatment. Treatment of cultured mouse brain microvascular endothelial cells with exosomes from H. pylori infected male, not female, mice significantly increased intracellular ROS production and impaired endothelial function with decreased migration, tube formation, and proliferation, which could be prevented with N-acetylcysteine treatment. H. pylori infection selectively impairs endothelial function in male mice due to exosome-mediated ROS formation.

Compressible viscoelasticity of cell membranes determined by gigahertz-frequency acoustic vibrations

Membrane viscosity is an important property of cell biology, which determines cellular function, development and disease progression. Various experimental and computational methods have been developed to investigate the mechanics of cells. However, there have been no experimental measurements of the membrane viscosity at high-frequencies in live cells. High frequency measurements are important because they can probe viscoelastic effects. Here, we investigate the membrane viscosity at gigahertz-frequencies through the damping of the acoustic vibrations of gold nanoplates. The experiments are modeled using a continuum mechanics theory which reveals that the membranes display viscoelasticity, with an estimated relaxation time of ca. 5.7+2.4/−2.7 ps. We further demonstrate that membrane viscoelasticity can be used to differentiate a cancerous cell line (the human glioblastoma cells LN-18) from a normal cell line (the mouse brain microvascular endothelial cells bEnd.3). The viscosity of cancerous cells LN-18 is lower than that of healthy cells bEnd.3 by a factor of three. The results indicate promising applications of characterizing membrane viscoelasticity at gigahertz-frequency in cell diagnosis.

PRIMARY CULTURE AND IDENTIFICATION OF MOUSE BRAIN MICROVASCULAR ENDOTHELIAL CELLS

Brain microvascular endothelial cells are the basic components of the blood-brain barrier. Many neurological diseases are related to the loss of blood brain barrier (BBB) function. Isolating and culturing primary BMVEC is an important means to study the function and regulation of BBB in vitro. To establish a method for isolation and culture of primary mouse brain microvascular endothelial cells (BMECs). The 7-10-days mice were sacrificed by neck removal, the cranial cavity was opened, the brain was aseptically removed and the cerebral cortex was retained. To extract brain microvascular segments, the brain underwent three D-Hank solution rinses. It was then homogenized, twice digested by enzyme, and centrifuged using a Bovine Serum Albumin (BSA) gradient. For primary culture, the brain microvascular segments were injected into gelatin-coated culture plates using DMED complete media. When the cell density reaches 90 %, the media is removed, and the cells are then given two PBS washes. A new medium was introduced after adding 1ml of the trypsin-EDTA solution to digest for 2–5 minutes for passage. Cell culture plates were rinsed and pre-cooled 95 % ethanol was added for 20 minutes after passaged cells had grown to 80–90 % of their original size. After a third wash, 1 ml of mouse factor VIII antibody was added to the culture wells, where it was left for 4 hours at 37 °C. FITC-labeled rabbit anti-mouse antibody in a volume of 1 mL was added. Under a confocal laser microscope, the plates were examined and taken pictures of. The outcome demonstrates positive expression of the marker factor VIII associated antigen. To create a cell suspension, monolayer-growing microvascular endothelial cells were chosen. 100 L of cell suspension was used to inoculate each well in 96-well plates, and the cells were then grown. On days 1, 2, 3, 4, 5, 6, and 7, the original medium was removed, and then 180 μL of DMEM and 20 μL of MTT were simultaneously added to each well for a 4-hour culture. After adding dimethyl sulfoxide (DMSO), each well's absorbance value (A value) was measured at 492 nm. The outcome demonstrates that the growth peak is attained between 6 and 8 days. This method can successfully isolate and culture primary BMECs, which lay a foundation for the study of BMEC in vitro.

The Aldose Reductase Inhibitor Epalrestat Maintains Blood–Brain Barrier Integrity by Enhancing Endothelial Cell Function during Cerebral Ischemia

Excessive activation of aldose reductase (AR) in the brain is a risk factor for aggravating cerebral ischemia injury. Epalrestat is the only AR inhibitor with proven safety and efficacy, which is used in the clinical treatment of diabetic neuropathy. However, the molecular mechanisms underlying the neuroprotection of epalrestat remain unknown in the ischemic brain. Recent studies have found that blood–brain barrier (BBB) damage was mainly caused by increased apoptosis and autophagy of brain microvascular endothelial cells (BMVECs) and decreased expression of tight junction proteins. Thus, we hypothesized that the protective effect of epalrestat is mainly related to regulating the survival of BMVECs and tight junction protein levels after cerebral ischemia. To test this hypothesis, a mouse model of cerebral ischemia was established by permanent middle cerebral artery ligation (pMCAL), and the mice were treated with epalrestat or saline as a control. Epalrestat reduced the ischemic volume, enhanced BBB function, and improved the neurobehavior after cerebral ischemia. In vitro studies revealed that epalrestat increased the expression of tight junction proteins, and reduced the levels of cleaved-caspase3 and LC3 proteins in mouse BMVECs (bEnd.3 cells) exposed to oxygen–glucose deprivation (OGD). In addition, bicalutamide (an AKT inhibitor) and rapamycin (an mTOR inhibitor) increased the epalrestat-induced reduction in apoptosis and autophagy related protein levels in bEnd.3 cells with OGD treatment. Our findings suggest that epalrestat improves BBB function, which may be accomplished by reducing AR activation, promoting tight junction proteins expression, and upregulating AKT/mTOR signaling pathway to inhibit apoptosis and autophagy in BMVECs.

Gli2-induced lncRNA Peg13 alleviates cerebral ischemia-reperfusion injury by suppressing Yy1 transcription in a PRC2 complex-dependent manner.

Endothelial cell dysfunction plays an important role in cerebral ischemia-reperfusion (I/R) injury. LncRNA Peg13 is reported to be down-regulated in brain microvascular endothelial cells (BMVECs) induced by glucose-oxygen deprivation (OGD), but the mechanism of its involvement in I/R progression remains to be further explored. Here, mouse BMVECs (bEnd.3 cells) were treated with OGD / reoxygenation (OGD/R) to simulate I/R injury in vitro. Peg13 and Gli2 expression was decreased in OGD/R-treated bEnd.3 cells. And overexpression of Peg13 or Gli2 prevented OGD/R-induced reduction in cell migration and angiogenesis, as well as upregulation in cell apoptosis and oxidative stress levels. Mechanism exploration showed that Gli2 promoted the transcription of Peg13. And Peg13 repressed Yy1 transcription by binding to Ezh2 (a key subunit of PRC2 complex) and inducing the enrichment of H3K27me3 in Yy1 promoter region, thereby suppressing the transcriptional inhibition effect of Yy1 on Notch3 and promoting the expression of Notch3. Consistently, Notch3 overexpression hindered OGD/R-induced endothelium dysfunction. In addition, a brain I/R injury model was established using middle cerebral artery occlusion surgery. And lentivirus-mediated Gli2 and Peg13 overexpression vectors were injected into mice via the lateral ventricle one week before surgery. The results showed that overexpression of Peg13 or Gli2 alleviated I/R-induced neurological deficit, cerebral infarct and cerebral edema. And simultaneous overexpression of Peg13 and Gli2 showed a better protective effect than overexpression of Gli2 or Peg13 alone. In conclusion, Peg13 regulated by Gli2 inhibits Yy1 transcription in a PCR2 complex-dependent manner, and blocks the transcriptional repression of Notch3 by Yy1, thereby exerting neuroprotective effects on cerebral I/R injury.

Benzo[b]fluoranthene (B[b]F) affects apoptosis, oxidative stress, mitochondrial membrane potential and expressions of blood-brain barrier markers in microvascular endothelial cells

Exposure to polycyclic aromatic hydrocarbons (PAHs) contributes to the damage of blood-brain barrier. While a number of studies were focused on benzo[a]pyrene, direct effects and mechanisms of benzo[b]fluoranthene (B[b]F), another main component of PAHs, on blood-brain barrier (BBB) are not documented. Here, we investigated if B[b]F at concentrations of environmental relevance could affect apoptosis, oxidative stress, mitochondrial membrane potential (MMP) and BBB marker expression in mouse brain microvascular endothelial (bEnd.3) cells, an in vitro model typically used to study BBB toxicology. Cells were treated with varying concentrations of B[b]F (0, 10, 20 and 40 μM) for 48 h. Cell proliferation, cell cycle, apoptosis, oxidative stress, MMP and BBB marker expressions were evaluated by label-free real-time cell analysis, flow cytometry, immunofluorescence and Western-blot. The proliferation of bEnd.3 cells was inhibited by B[b]F in a concentration dependent manner. B[b]F treatment significantly affected cell cycle, induced apoptosis, increased levels of reactive oxygen species (ROS) and disputed MMP. Expressions of BBB marker Occludin and Claudin-5 were decreased in the presence of 40 μM B[b]F. In conclusion, B[b]F might damage BBB by affecting proliferation, apoptosis, ROS level and Occludin and Claudin-5 expressions in microvascular endothelial cells.

Cerium oxide nanoparticles with antioxidative neurorestoration for ischemic stroke

Oxidative stress and mitochondrial damage are the main mechanisms of ischemia-reperfusion injury in ischemic stroke. Herein, cerium oxide nanoparticles with powerful free radical scavenging ability were used as carriers to load dl-3-n-butylphthalide (NBP–CeO2 NPs) for the combined treatment of ischemic stroke. NBP-CeO2 NPs could eliminate reactive oxygen species (ROS) in mouse brain microvascular endothelial cells and hippocampal neurons after oxygen-glucose deprivation/reoxygenation (OGD/R), and also save mitochondrial membrane potential, morphology, and function, thus alleviating the in vitro blood brain barrier (BBB) disruption and neuronal apoptosis. In the middle cerebral artery embolization/recanalization (MCAO/R) mouse model, the NBP-CeO2 NPs also possessed superior ROS scavenging ability, protected mitochondria, and preserved BBB integrity, thereby reducing cerebral infarction and cerebral edema and inhibiting neuroinflammation and neuronal apoptosis. The long-term neurobehavioral tests indicated that the NBP-CeO2 NPs significantly improved sensorimotor function and spatial learning ability by promoting angiogenesis after ischemic stroke. Therefore, the NBP-CeO2 NPs provided a novel therapeutic approach for ischemic stroke by combining antioxidant and neurovascular repair abilities, highlighting its wide application in ischemia-reperfusion injury.

Screening of infection conditions for brain microvascular endothelial cells infected by Streptococcus suis

Streptococcus suis is a pathogen that causes swine meningitis, sepsis, and other diseases. There are 34 serotypes, of which type 2 is the most pathogenic. During the infection process of Streptococcus suis, several major virulence factors are involved and play a different roles. Streptococcal meningitis is caused by the bacteria’s ability to cross the blood-brain barrier and enter the central nervous system. Therefore, studying the interaction between Streptococcus suis and cerebral microvascular endothelial cells will help reveal meningitis's pathogenic mechanism. When studying the interaction between bacteria and cells, the number of infected bacteria and the time of infection are very important. In this study, Streptococcus suis serotype two was made into bacteria liquid and counted. Then bacteria were used to infect mouse brain microvascular endothelial cells with different multiplicity of infection (1,10,100 and 200). Cells were harvested at six h, nine h,12h,18h, and 24h after infection. The total RNAs of harvested cells were extracted, and the concentration of RNA was detected. The OD260/OD280 was between 1.8~2.4, OD260/OD230 was 1.5~2.4, and the concentration was greater than 100ng/µL. Total RNAs were reverse transcribed to cDNAs used to perform quantitative PCR to detect the mRNA expression of IL-18, IL-1beta, IL-6, and IL-10. The results showed that each MOI group's mRNA expression is higher than the control group with different infection times. When the multiplicity of infection is at 1, each group's relative expression of cytokines reaches a peak at 18hrs after infection. When the multiplicity of infection is at 10, each group's relative expression of cytokines reaches a peak at 12hrs after infection. When the multiplicity of infection is at 100, the relative expression of cytokines reaches a peak at 12hrs after infection. When the multiplicity of infection is at 200, the relative expressions of each cytokine reach a peak at 6hrs after infection. Based on the mRNA relative expression of each cytokine under different conditions, the optimal multiplicity of infection was 100, and the optimal infection time was 12h. The result provides a basis for the study of the pathogenic mechanism of meningitis.

Lipopolysaccharide downregulates the expression of ZO-1 protein through the Akt pathway

BackgroundNeonatal bacterial meningitis is a common neonatal disease with high morbidity, and can cause serious sequelae when left untreated. Escherichia coli is the common pathogen, and its endotoxin, lipopolysaccharide (LPS) can damage the endothelial cells, increasing the permeability of the blood-brain barrier (BBB), leading to intracranial inflammation. However, the specific mechanism of bacterial meningitis induced by LPS damaging BBB remains unclear. In this study, the mouse brain microvascular endothelial (bEND.3) cells were used as a research object to investigate whether LPS damage BBB through the PI3K/Akt pathway.MethodsThe bEND.3 cells were stimulated with different concentrations of LPS for 12 h, and the expression of tight junction proteins (ZO-1, claudin-5, occludin) was detected using western blotting. The cells were challenged with the same concentration of LPS (1ug/ml) across different timepoints (0, 2 h, 4 h, 6 h, 12 h, 24 h). Expression of TJ proteins and signal pathway molecules (PI3K, p-PI3K, Akt, p-Akt) were detected. The distribution of ZO-1 in bEND.3 cells were detected by immunofluorescence staining.ResultsA negative correlation is observed between ZO-1 and LPS concentration. Moreover, a reduced expression of ZO-1 was most significant under 1 ug/ml of LPS, and the difference was statistically significant (P < 0.05). Additionally, there is a negative correlation between ZO-1 and LPS stimulation time. Meanwhile, the expression of claudin-5 and occludin did not change significantly with the stimulation of LPS concentration and time. The immunofluorescence assay showed that the amount of ZO-1 on the surface of bEND.3 cells stimulated with LPS was significantly lower than that of the control group. After LPS stimulation, p-Akt protein increased at 2 h and peaked at 4 h. The titer of p-PI3K did not change significantly with time.ConclusionLPS can downregulate the expression of ZO-1; however, its effect on claudin-5 and occludin is minimal. Akt signal pathway may be involved in the regulation of ZO-1 expression induced by LPS in bEND.3 cells.