In vitro evidence for the brain glutamate efflux hypothesis: Brain endothelial cells cocultured with astrocytes display a polarized brain-to-blood transport of glutamate

Glia ◽  
2012 ◽  
Vol 60 (6) ◽  
pp. 882-893 ◽  
Author(s):  
Hans Christian Helms ◽  
Rasmus Madelung ◽  
Helle Sønderby Waagepetersen ◽  
Carsten Uhd Nielsen ◽  
Birger Brodin
Keyword(s):  
Endothelial Cells ◽  
Brain Endothelial Cells ◽  
Blood Transport ◽  
The Brain ◽  
Glutamate Efflux

scholarly journals Two peptides targeting endothelial receptors are internalized into murine brain endothelial cells

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0249686
Author(s):  
Diána Hudecz ◽  
Sara Björk Sigurdardóttir ◽  
Sarah Christine Christensen ◽  
Casper Hempel ◽  
Andrew J. Urquhart ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Transferrin Receptor ◽  
Vesicular Transport ◽  
Brain Diseases ◽  
Brain Endothelial Cells ◽  
Binding Studies ◽  
Wide Range ◽  
Murine Brain ◽  
The Brain

The blood-brain barrier (BBB) is one of the main obstacles for therapies targeting brain diseases. Most macromolecules fail to pass the tight BBB, formed by brain endothelial cells interlinked by tight junctions. A wide range of small, lipid-soluble molecules can enter the brain parenchyma via diffusion, whereas macromolecules have to transcytose via vesicular transport. Vesicular transport can thus be utilized as a strategy to deliver brain therapies. By conjugating BBB targeting antibodies and peptides to therapeutic molecules or nanoparticles, it is possible to increase uptake into the brain. Previously, the synthetic peptide GYR and a peptide derived from melanotransferrin (MTfp) have been suggested as candidates for mediating transcytosis in brain endothelial cells (BECs). Here we study uptake, intracellular trafficking, and translocation of these two peptides in BECs. The peptides were synthesized, and binding studies to purified endocytic receptors were performed using surface plasmon resonance. Furthermore, the peptides were conjugated to a fluorophore allowing for live-cell imaging studies of their uptake into murine brain endothelial cells. Both peptides bound to low-density lipoprotein receptor-related protein 1 (LRP-1) and the human transferrin receptor, while lower affinity was observed against the murine transferrin receptor. The MTfp showed a higher binding affinity to all receptors when compared to the GYR peptide. The peptides were internalized by the bEnd.3 mouse endothelial cells within 30 min of incubation and frequently co-localized with endo-lysosomal vesicles. Moreover, our in vitro Transwell translocation experiments confirmed that GYR was able to cross the murine barrier and indicated the successful translocation of MTfp. Thus, despite binding to endocytic receptors with different affinities, both peptides are able to transcytose across the murine BECs.

scholarly journals Polarized α-synuclein trafficking and transcytosis across Brain Endothelial Cells via Rab7-decorated carriers

2021 ◽  
Author(s):  
Parvez Alam ◽  
Mikkel Roland Holst ◽  
Line Laursen ◽  
Janni Nielsen ◽  
Simone Nielsen ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Vesicular Transport ◽  
Alpha Synuclein ◽  
Brain Endothelial Cells ◽  
Direct Role ◽  
Peripheral Tissues ◽  
Parkinsons Disease ◽  
Therapeutic Implications ◽  
The Brain

Parkinsons disease is mainly caused by aggregation of alpha-synuclein (α-syn) in the brain. Exchange of α-syn between the brain and peripheral tissues could have important pathophysiological and therapeutic implications, but the trafficking mechanism of α-syn across the blood brain barrier (BBB) remains unclear. In this study, we therefore investigated uptake and transport mechanisms of α-syn monomers and oligomers across an in vitro BBB model system. Both α-syn monomers and oligomers were internalized by primary brain endothelial cells, with increased restriction of oligomeric over monomeric transport. To enlighten the trafficking route of monomeric α-syn in brain endothelial cells, we investigated co-localization of α-syn and intracellular markers of vesicular transport. Here, we observed the highest colocalization with clathrin, Rab7 and VPS35, suggesting a clathrin-dependent internalization, preferentially followed by a late endosome retromer-connected trafficking pathway. Furthermore, STED microscopy revealed monomeric α-syn trafficking via Rab7-decorated carriers. Knockdown of Caveolin1, VPS35, and Rab7 using siRNA did not affect monomeric α-syn uptake into endothelial cells. However, it significantly reduced transcytosis of monomeric α-syn in the luminal-abluminal direction, suggesting a polarized regulation of monomeric α-syn vesicular transport. Our findings suggest a direct role for Rab7 in polarized trafficking of monomeric α-syn across BBB endothelium, and the potential of Rab7 directed trafficking to constitute a target pathway for new therapeutic strategies against Parkinsons disease and related synucleinopathies.

scholarly journals Nonlytic exocytosis of Cryptococcus neoformans from neutrophils in the brain vasculature

2019 ◽  
Vol 17 (1) ◽  
Author(s):  
Xiaofan Yang ◽  
Huijuan Wang ◽  
Fan Hu ◽  
Xichen Chen ◽  
Mingshun Zhang
Keyword(s):  
Endothelial Cells ◽  
Cryptococcus Neoformans ◽  
Actin Polymerization ◽  
Brain Endothelial Cells ◽  
Brain Vasculature ◽  
Mouse Brain Endothelial Cells ◽  
Immunodeficiency Syndrome ◽  
Brain Microvasculature ◽  
The Brain

Abstract Background Cryptococcus neoformans (C. neoformans) is an encapsulated budding yeast that causes life-threatening meningoencephalitis in immunocompromised individuals, especially those with acquired immunodeficiency syndrome (AIDS). To cause meningoencephalitis, C. neoformans circulating in the bloodstream must first be arrested in the brain microvasculature. Neutrophils, the most abundant phagocytes in the bloodstream and the first leukocytes to be recruited to an infection site, can ingest C. neoformans. Little is known about how neutrophils interact with arrested fungal cells in the brain microvasculature. Methods A blood-brain barrier (BBB) in vitro model was established. The interactions between neutrophils adhering to brain endothelial cells and fungi were observed under a live cell imaging microscope. A flow cytometry assay was developed to explore the mechanisms. Immunofluorescence staining of brain tissues was utilized to validate the in vitro phenomena. Results Using real-time imaging, we observed that neutrophils adhered to a monolayer of mouse brain endothelial cells could expel ingested C. neoformans without lysis of the neutrophils or fungi in vitro, demonstrating nonlytic exocytosis of fungal cells from neutrophils. Furthermore, nonlytic exocytosis of C. neoformans from neutrophils was influenced by either the fungus (capsule and viability) or the neutrophil (phagosomal pH and actin polymerization). Moreover, nonlytic exocytosis of C. neoformans from neutrophils was recorded in brain tissue. Conclusion These results highlight a novel function by which neutrophils extrude C. neoformans in the brain vasculature. Graphical abstract

scholarly journals The insulin receptor is expressed and functional in cultured blood-brain barrier endothelial cells but does not mediate insulin entry from blood to brain

2018 ◽  
Vol 315 (4) ◽  
pp. E531-E542 ◽  
Author(s):  
Maria Hersom ◽  
Hans C. Helms ◽  
Christoffer Schmalz ◽  
Thomas Å. Pedersen ◽  
Stephen T. Buckley ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Insulin Receptor ◽  
Blood Brain Barrier ◽  
Brain Barrier ◽  
Brain Endothelial Cells ◽  
Insulin Transport ◽  
Blood Brain ◽  
The Brain ◽  
Receptor Inhibitor

Insulin and its receptor are known to be present and functional in the brain. Insulin cerebrospinal fluid concentrations have been shown to correlate with plasma levels of insulin in a nonlinear fashion, indicative of a saturable transport pathway from the blood to the brain interstitial fluid. The aim of the present study was to investigate whether insulin was transported across brain endothelial cells in vitro via an insulin receptor-dependent pathway. The study showed that the insulin receptor was expressed at both the mRNA and protein levels in bovine brain endothelial cells. Luminally applied radiolabeled insulin showed insulin receptor-mediated binding to the endothelial cells. This caused a dose-dependent increase in Akt-phosphorylation, which was inhibited by coapplication of an insulin receptor inhibitor, s961, demonstrating activation of insulin receptor signaling pathways. Transport of insulin across the blood-brain barrier in vitro was low and comparable to that of a similarly sized paracellular marker. Furthermore, insulin transport was not inhibited by coapplication of an excess of unlabeled insulin or an insulin receptor inhibitor. The insulin transport and uptake studies were repeated in mouse brain endothelial cells demonstrating similar results. Although it cannot be ruled out that culture-induced changes in the cell model could have impaired a potential insulin transport mechanism, these in vitro data indicate that peripheral insulin must reach the brain parenchyma through alternative pathways rather than crossing the blood-brain barrier via receptor mediated transcytosis.

scholarly journals Combination of Alanine and Glutathione as Targeting Ligands of Nanoparticles Enhances Cargo Delivery into the Cells of the Neurovascular Unit

Pharmaceutics ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 635
Author(s):  
Gergő Porkoláb ◽  
Mária Mészáros ◽  
András Tóth ◽  
Anikó Szecskó ◽  
András Harazin ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Cultured Cells ◽  
Neurological Diseases ◽  
Neurovascular Unit ◽  
Cell Types ◽  
Target Cells ◽  
Brain Endothelial Cells ◽  
Multiple Ligands ◽  
The Brain

Inefficient drug delivery across the blood–brain barrier (BBB) and into target cells in the brain hinders the treatment of neurological diseases. One strategy to increase the brain penetration of drugs is to use vesicular nanoparticles functionalized with multiple ligands of BBB transporters as vehicles. Once within the brain, however, drugs must also be able to reach their therapeutic targets in the different cell types. It is, therefore, favorable if such nanocarriers are designed that can deliver their cargo not only to brain endothelial cells, but to other cell types as well. Here, we show that alanine-glutathione dual-targeting of niosomes enhances the delivery of a large protein cargo into cultured cells of the neurovascular unit, namely brain endothelial cells, pericytes, astrocytes and neurons. Furthermore, using metabolic and endocytic inhibitors, we show that the cellular uptake of niosomes is energy-dependent and is partially mediated by endocytosis. Finally, we demonstate the ability of our targeted nanovesicles to deliver their cargo into astroglial cells after crossing the BBB in vitro. These data indicate that dual-labeling of nanoparticles with alanine and glutathione can potentially be exploited to deliver drugs, even biopharmacons, across the BBB and into multiple cell types in the brain.

scholarly journals Age influences susceptibility of brain capillary endothelial cells to La Crosse virus infection and cell death

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Rahul Basu ◽  
Vinod Nair ◽  
Clayton W. Winkler ◽  
Tyson A. Woods ◽  
Iain D. C. Fraser ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Cell Death ◽  
Virus Infection ◽  
La Crosse Virus ◽  
Brain Capillary ◽  
Adult Mice ◽  
Age Related ◽  
Capillary Endothelial Cells ◽  
The Brain

Abstract Background A key factor in the development of viral encephalitis is a virus crossing the blood-brain barrier (BBB). We have previously shown that age-related susceptibility of mice to the La Crosse virus (LACV), the leading cause of pediatric arbovirus encephalitis in the USA, was associated with the ability of the virus to cross the BBB. LACV infection in weanling mice (aged around 3 weeks) results in vascular leakage in the olfactory bulb/tract (OB/OT) region of the brain, which is not observed in adult mice aged > 6–8 weeks. Thus, we studied age-specific differences in the response of brain capillary endothelial cells (BCECs) to LACV infection. Methods To examine mechanisms of LACV-induced BBB breakdown and infection of the CNS, we analyzed BCECs directly isolated from weanling and adult mice as well as established a model where these cells were infected in vitro and cultured for a short period to determine susceptibility to virus infection and cell death. Additionally, we utilized correlative light electron microscopy (CLEM) to examine whether changes in cell morphology and function were also observed in BCECs in vivo. Results BCECs from weanling, but not adult mice, had detectable infection after several days in culture when taken ex vivo from infected mice suggesting that these cells could be infected in vitro. Further analysis of BCECs from uninfected mice, infected in vitro, showed that weanling BCECs were more susceptible to virus infection than adult BCECs, with higher levels of infected cells, released virus as well as cytopathic effects (CPE) and cell death. Although direct LACV infection is not detected in the weanling BCECs, CLEM analysis of brain tissue from weanling mice indicated that LACV infection induced significant cerebrovascular damage which allowed virus-sized particles to enter the brain parenchyma. Conclusions These findings indicate that BCECs isolated from adult and weanling mice have differential viral load, infectivity, and susceptibility to LACV. These age-related differences in susceptibility may strongly influence LACV-induced BBB leakage and neurovascular damage allowing virus invasion of the CNS and the development of neurological disease.

Anthropogenic Iron Oxide Nanoparticles Induce Damage to Brain Microvascular Endothelial Cells Forming the Blood-Brain Barrier

2021 ◽  
Author(s):  
Lorena Gárate-Vélez ◽  
Claudia Escudero-Lourdes ◽  
Daniela Salado-Leza ◽  
Armando González-Sánchez ◽  
Ildemar Alvarado-Morales ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Blood Brain Barrier ◽  
Brain Barrier ◽  
Microvascular Endothelial Cells ◽  
Brain Microvascular Endothelial Cells ◽  
Blood Brain ◽  
Fe3o4 Nps ◽  
Microvascular Endothelial ◽  
The Brain

Background: Iron nanoparticles, mainly in magnetite phase (Fe3O4 NPs), are released to the environment in areas with high traffic density and braking frequency. Fe3O4 NPs were found in postmortem human brains and are assumed to get directly into the brain through the olfactory nerve. However, these pollution-derived NPs may also translocate from the lungs to the bloodstream and then, through the blood-brain barrier (BBB), into the brain inducing oxidative and inflammatory responses that contribute to neurodegeneration. Objective: To describe the interaction and toxicity of pollution-derived Fe3O4 NPs on primary rat brain microvascular endothelial cells (rBMECs), main constituents of in vitro BBB models. Methods: Synthetic bare Fe3O4 NPs that mimic the environmental ones (miFe3O4) were synthesized by co-precipitation and characterized using complementary techniques. The rBMECs were cultured in Transwell® plates. The NPs-cell interaction was evaluated through transmission electron microscopy and standard colorimetric in vitro assays. Results: The miFe3O4 NPs, with a mean diameter of 8.45 ± 0.14 nm, presented both magnetite and maghemite phases, and showed super-paramagnetic properties. Results suggest that miFe3O4 NPs are internalized by rBMECs through endocytosis and that they are able to cross the cells monolayer. The lowest miFe3O4 NPs concentration tested induced mid cytotoxicity in terms of 1) membrane integrity (LDH release) and 2) metabolic activity (MTS transformation). Conclusion: Pollution-derived Fe3O4 NPs may interact and cross the microvascular endothelial cells forming the BBB and cause biological damage.

scholarly journals Estrogen-Receptor-Mediated Protection of Cerebral Endothelial Cell Viability and Mitochondrial Function after Ischemic Insult in vitro

2009 ◽  
Vol 30 (3) ◽  
pp. 545-554 ◽  
Author(s):  
Jiabin Guo ◽  
Diana N Krause ◽  
James Horne ◽  
John H Weiss ◽  
Xuejun Li ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Estrogen Receptor ◽  
Endothelial Cell ◽  
Cell Viability ◽  
Mitochondrial Function ◽  
Protective Effects ◽  
Brain Endothelial Cells ◽  
Ischemic Insult ◽  
Mitochondrial Superoxide

Protective effects of estrogen against experimental stroke and neuronal ischemic insult are well-documented, but it is not known whether estrogen prevents ischemic injury to brain endothelium, a key component of the neurovascular unit. Increasing evidence indicates that estrogen exerts protective effects through mitochondrial mechanisms. We previously found 17β-estradiol (E2) to improve mitochondrial efficiency and reduce mitochondrial superoxide in brain blood vessels and endothelial cells. Thus we hypothesized E2 will preserve mitochondrial function and protect brain endothelial cells against ischemic damage. To test this, an in vitro ischemic model, oxygen-glucose deprivation (OGD)/reperfusion, was applied to immortalized mouse brain endothelial cells (bEnd.3). OGD/reperfusion-induced cell death was prevented by long-term (24, 48 h), but not short-term (0.5, 12 h), pretreatment with 10 nmol/L E2. Protective effects of E2 on endothelial cell viability were mimicked by an estrogen-receptor (ER) agonist selective for ERα (PPT), but not by one selective for ERβ (DPN). In addition, E2 significantly decreased mitochondrial superoxide and preserved mitochondrial membrane potential and ATP levels in early stages of OGD/reperfusion. All of the E2 effects were blocked by the ER antagonist, ICI-182,780. These findings indicate that E2 can preserve endothelial mitochondrial function and provide protection against ischemic injury through ER-mediated mechanisms.

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