scholarly journals Insights Into the Mechanisms of Brain Endothelial Erythrophagocytosis

2021 ◽  
Vol 9 ◽  
Author(s):  
Jiahong Sun ◽  
Prema Vyas ◽  
Samar Mann ◽  
Annlia Paganini-Hill ◽  
Ane C. F. Nunes ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Prussian Blue ◽  
Degradation Products ◽  
Annexin V ◽  
Brain Endothelium ◽  
Cellular Mechanisms ◽  
Phosphatidylserine Exposure ◽  
The Brain

The endothelial cells which form the inner cellular lining of the vasculature can act as non-professional phagocytes to ingest and remove emboli and aged/injured red blood cells (RBCs) from circulation. We previously demonstrated an erythrophagocytic phenotype of the brain endothelium for oxidatively stressed RBCs with subsequent migration of iron-rich RBCs and RBC degradation products across the brain endothelium in vivo and in vitro, in the absence of brain endothelium disruption. However, the mechanisms contributing to brain endothelial erythrophagocytosis are not well defined, and herein we elucidate the cellular mechanisms underlying brain endothelial erythrophagocytosis. Murine brain microvascular endothelial cells (bEnd.3 cells) were incubated with tert-butyl hydroperoxide (tBHP, oxidative stressor to induce RBC aging in vitro)- or PBS (control)-treated mouse RBCs. tBHP increased the reactive oxygen species (ROS) formation and phosphatidylserine exposure in RBCs, which were associated with robust brain endothelial erythrophagocytosis. TNFα treatment potentiated the brain endothelial erythrophagocytosis of tBHP-RBCs in vitro. Brain endothelial erythrophagocytosis was significantly reduced by RBC phosphatidylserine cloaking with annexin-V and with RBC-ROS and phosphatidylserine reduction with vitamin C. Brain endothelial erythrophagocytosis did not alter the bEnd.3 viability, and tBHP-RBCs were localized with early and late endosomes. Brain endothelial erythrophagocytosis increased the bEnd.3 total iron pool, abluminal iron levels without causing brain endothelial monolayer disruption, and ferroportin levels. In vivo, intravenous tBHP-RBC injection in aged (17–18 months old) male C57BL/6 mice significantly increased the Prussian blue-positive iron-rich lesion load compared with PBS-RBC-injected mice. In conclusion, RBC phosphatidylserine exposure and ROS are key mediators of brain endothelial erythrophagocytosis, a process which is associated with increased abluminal iron in vitro. tBHP-RBCs result in Prussian blue-positive iron-rich lesions in vivo. Brain endothelial erythrophagocytosis may provide a new route for RBC/RBC degradation product entry into the brain to produce iron-rich cerebral microhemorrhage-like lesions.

Differences between in vitro and in vivo degradation of LHRH by rat brain and other organs

1987 ◽  
Vol 253 (3) ◽  
pp. E317-E321 ◽  
Author(s):  
F. A. Carone ◽  
M. A. Stetler-Stevenson ◽  
V. May ◽  
A. LaBarbera ◽  
G. Flouret
Keyword(s):  
Degradation Products ◽  
Venous Blood ◽  
Simultaneous Action ◽  
Pituitary Cells ◽  
Time Intervals ◽  
Luteinizing Hormone Releasing Hormone ◽  
Hydrolysis Of ◽  
The Brain

Homogenates of brain, pituitary, liver, lung, ovary, and testes were incubated with [pyro Glu1-3,4-3H]luteinizing hormone-releasing hormone ([3H]LHRH), and the profiles of metabolites generated as a function of time were determined. After 5 min of incubation, 5 was the predominant metabolite in most homogenates. Although the profiles of metabolites varied at different time intervals, metabolites 2, 3, 4, and 5, and in some instances 7 and 9, appeared to form simultaneously and were detectable at 10 min. Neither metabolite 6 nor other larger metabolites formed initially as dominant degradation products. The findings suggest cleavage of LHRH by the simultaneous action of several endopeptidases. After a single vascular transit of [3H]LHRH, metabolites were determined in the venous blood of liver, lung, and brain of rats in vivo. There were no metabolites of [3H]LHRH in venous blood of liver and lung; however, metabolites 2-4 were present in venous blood of the brain. Incubation of rat anterior pituitary cells with [3H]LHRH yielded metabolites 1-4 but not metabolites 5 or 9 as in homogenates. Incubation of [3H]LHRH with porcine follicular granulosa cells resulted in the generation of metabolites 2-7 and 9, similar to the profile in homogenates. Thus, since homogenates contain enzymes of disrupted cells, they do not always reflect mechanisms for in vivo hydrolysis of circulating LHRH. Brain degraded 12.1% of LHRH during a single vascular transit and may account for substantial degradation of the circulating hormone.

Abstract TP478: Mechanisms of Brain Endothelial Erythrophagocytosis: Insights Into the Pathogenesis of Cerebral Microbleeds

Stroke ◽  
2020 ◽  
Vol 51 (Suppl_1) ◽  
Author(s):  
Jiahong Sun ◽  
Prema Vyas ◽  
Samar Mann ◽  
Sriyansh Yarlagadda ◽  
Mark J Fisher ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Vitamin C ◽  
Annexin V ◽  
Cerebral Microbleeds ◽  
Endosomal Trafficking ◽  
Brain Endothelial Cells ◽  
Brain Endothelium ◽  
Cellular Mechanisms ◽  
Microvascular Endothelium ◽  
Late Endosomes

Background: Cerebral microbleeds, MRI signatures of cerebral microhemorrhage, are thought to arise from brain microvessel disruption. Our prior work suggests an alternate origin for some microbleeds, emphasizing brain endothelial erythrophagocytosis (BEE) producing microhemorrhage-like lesions (“pseudo-microbleeds”) in absence of vascular disruption (Frontiers Cell Neurosci 9-18; PMID: 30237761). We demonstrated an erythrophagocytic phenotype of brain microvascular endothelium for oxidatively-stressed red blood cells (RBC), and migration of iron-rich hemoglobin across the brain endothelium. However, cellular mechanisms underlying BEE and hemoglobin passage across brain endothelium are not defined. Herein we investigated a) role of oxidative stress and RBC phosphatidylserine (PS) exposure in BEE and b) intracellular endosomal trafficking of RBC within brain endothelial cells. Methods: Murine brain endothelial cells (bEnd.3 cells) were incubated with 2x10 6 mouse RBC treated with 3mM tert-butylhydroperoxide (t-BHP, an oxidative stressor) or sterile PBS (control) for 48h at 37°C, in the presence of 7.5 μg annexin V to cloak PS, or vitamin C (15μM-1500μM) to reduce reactive oxygen species (ROS). BEE was evaluated by hematoxylin & eosin stain and diaminofluorene assay for hemoglobin. RBC ROS levels, PS exposure, and cell viability were measured. bEnd.3 cells were immunostained to visualize RBC in early and late endosomes, the latter being the presumed site of RBC degradation post-erythrophagocytosis. Results: tBHP induced both ROS production and PS exposure in RBC. There was a 9-fold increase (p<0.001) in BEE of t-BHP-RBC compared with control. Vitamin C reduced RBC ROS levels (70%, p<0.001) and PS exposure (27%, p<0.001), while annexin V blocked RBC PS exposure (65%, p<0.001). BEE was significantly attenuated by annexin V (63%, p<0.001) and vitamin C (39%, p<0.001). No change in bEnd.3 viability was observed and t-BHP-RBC localized to both early and late endosomes. Conclusions: These data demonstrate the importance of RBC PS exposure in BEE, and describe the intracellular trafficking of RBC in brain endothelial cells. These findings provide insights into the development of microhemorrhage-like lesions and cerebral microbleeds.

scholarly journals Neurobiological After-Effects of Low Intensity Transcranial Electric Stimulation of the Human Nervous System: From Basic Mechanisms to Metaplasticity

2021 ◽  
Vol 12 ◽  
Author(s):  
Sohaib Ali Korai ◽  
Federico Ranieri ◽  
Vincenzo Di Lazzaro ◽  
Michele Papa ◽  
Giovanni Cirillo
Keyword(s):  
Transcranial Electrical Stimulation ◽  
Cellular Mechanisms ◽  
After Effects ◽  
Brain Functions ◽  
Non Invasive ◽  
Low Intensity ◽  
The Brain ◽  
Human Nervous System

Non-invasive low-intensity transcranial electrical stimulation (tES) of the brain is an evolving field that has brought remarkable attention in the past few decades for its ability to directly modulate specific brain functions. Neurobiological after-effects of tES seems to be related to changes in neuronal and synaptic excitability and plasticity, however mechanisms are still far from being elucidated. We aim to review recent results from in vitro and in vivo studies that highlight molecular and cellular mechanisms of transcranial direct (tDCS) and alternating (tACS) current stimulation. Changes in membrane potential and neural synchronization explain the ongoing and short-lasting effects of tES, while changes induced in existing proteins and new protein synthesis is required for long-lasting plastic changes (LTP/LTD). Glial cells, for decades supporting elements, are now considered constitutive part of the synapse and might contribute to the mechanisms of synaptic plasticity. This review brings into focus the neurobiological mechanisms and after-effects of tDCS and tACS from in vitro and in vivo studies, in both animals and humans, highlighting possible pathways for the development of targeted therapeutic applications.

scholarly journals Multifunctional Superparamagnetic Stiff Nanoreservoirs for Blood Brain Barrier Applications

Nanomaterials ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 449 ◽  
Author(s):  
Zulema Vargas-Osorio ◽  
Andrés Da Silva-Candal ◽  
Yolanda Piñeiro ◽  
Ramón Iglesias-Rey ◽  
Tomas Sobrino ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Vascular Endothelial Cells ◽  
Neurological Diseases ◽  
Developed Countries ◽  
Large Set ◽  
In Vivo Experiments ◽  
Liver And Kidney ◽  
The Brain

Neurological diseases (Alzheimer’s disease, Parkinson’s disease, and stroke) are becoming a major concern for health systems in developed countries due to the increment of ageing in the population, and many resources are devoted to the development of new therapies and contrast agents for selective imaging. However, the strong isolation of the brain by the brain blood barrier (BBB) prevents not only the crossing of pathogens, but also a large set of beneficial drugs. Therefore, an alternative strategy is arising based on the anchoring to vascular endothelial cells of nanoplatforms working as delivery reservoirs. In this work, novel injectable mesoporous nanorods, wrapped by a fluorescent magnetic nanoparticles envelope, are proposed as biocompatible reservoirs with an extremely high loading capacity, surface versatility, and optimal morphology for enhanced grafting to vessels during their diffusive flow. Wet chemistry techniques allow for the development of mesoporous silica nanostructures with tailored properties, such as a fluorescent response suitable for optical studies, superparamagnetic behavior for magnetic resonance imaging MRI contrast, and large range ordered porosity for controlled delivery. In this work, fluorescent magnetic mesoporous nanorods were physicochemical characterized and tested in preliminary biological in vitro and in vivo experiments, showing a transversal relaxivitiy of 324.68 mM−1 s−1, intense fluorescence, large specific surface area (300 m2 g−1), and biocompatibility for endothelial cells’ uptake up to 100 µg (in a 80% confluent 1.9 cm2 culture well), with no liver and kidney disability. These magnetic fluorescent nanostructures allow for multimodal MRI/optical imaging, the allocation of therapeutic moieties, and targeting of tissues with specific damage.

scholarly journals Microembolus clearance through angiophagy is an auxiliary mechanism preserving tissue perfusion in the rat brain

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Anne-Eva van der Wijk ◽  
Theodosia Georgakopoulou ◽  
Jisca Majolée ◽  
Jan S. M. van Bezu ◽  
Miesje M. van der Stoel ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Tissue Perfusion ◽  
Brain Parenchyma ◽  
Cytoskeletal Remodeling ◽  
The Common ◽  
The Brain ◽  
Auxiliary Mechanism ◽  
Fibrin Clots

AbstractConsidering its intolerance to ischemia, it is of critical importance for the brain to efficiently process microvascular occlusions and maintain tissue perfusion. In addition to collateral microvascular flow and enzymatic degradation of emboli, the endothelium has the potential to engulf microparticles and thereby recanalize the vessel, through a process called angiophagy. Here, we set out to study the dynamics of angiophagy in relation to cytoskeletal remodeling in vitro and reperfusion in vivo. We show that polystyrene microspheres and fibrin clots are actively taken up by (brain) endothelial cells in vitro, and chart the dynamics of the actin cytoskeleton during this process using live cell imaging. Whereas microspheres were taken up through the formation of a cup structure by the apical endothelial membrane, fibrin clots were completely engulfed by the cells, marked by dense F-actin accumulation surrounding the clot. Both microspheres and fibrin clots were retained in the endothelial cells. Notably, fibrin clots were not degraded intracellularly. Using an in vivo microembolization rat model, in which microparticles are injected into the common carotid artery, we found that microspheres are transported by the endothelium from the microvasculature into the brain parenchyma. Microembolization with microspheres caused temporal opening of the blood–brain barrier and vascular nonperfusion, followed by microsphere extravasation and restoration of vessel perfusion over time. Taken together, angiophagy is accompanied by active cytoskeletal remodeling of the endothelium, and is an effective mechanism to restore perfusion of the occluded microvasculature in vivo.

Endothelial cell phagocytosis of senescent neutrophils decreases procoagulant activity

2013 ◽  
Vol 109 (06) ◽  
pp. 1079-1090 ◽  
Author(s):  
Shuchuan Liu ◽  
Fenglin Cao ◽  
Yue Liu ◽  
Ruishuang Ma ◽  
Yu Si ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Apoptotic Cell ◽  
Procoagulant Activity ◽  
Human Neutrophils ◽  
Coagulation Time ◽  
Phosphatidylserine Exposure ◽  
Experimental Approaches ◽  
Vascular Compartment

SummaryAbundant senescent neutrophils traverse the vascular compartment and may contribute to pathologic conditions. For example, they become procoagulant when undergoing apoptosis and may contribute to thrombosis or inflammation. Our previous studies demonstrated a dominant clearance pathway in which the neutrophils can be phagocytosed by liver macrophages. The aim of this study was to explore an alternate pathway of neutrophil clearance by endothelial cells. Phagocytosis of the neutrophils by endothelial cells was performed using various experimental approaches including flow cytometry, confocal microscopy and electron microscopy assays in vitro and in vivo. Procoagulant activity of cultured neutrophils was evaluated by coagulation time, factor Xase and prothrombinase assays. Lactadherin functioned as a novel probe for the detection of phosphatidylserine on apoptotic cells, an opsonin (bridge) between apoptotic cell and phagocyte for promoting phagocytosis, and an efficient anticoagulant for inhibition of factor Xase and thrombin formation. When cultured, purified human neutrophils spontaneously entered apoptosis and developed procoagulant activity that was directly related to the degree of phosphatidylserine exposure. Co-culture of aged neutrophils and endothelial cells resulted in phagocytosis of the neutrophils and prolonged coagulation time. Lactadherin diminished the procoagulant activity and increased the rate of neutrophil clearance. In vivo, neutrophils were sequestered by endothelial cells after blockade of Kupffer cells, a process that was dependent upon both phosphatidylserine exposure and P-selectin expression. Thus, the ability of endothelial cells to clear senescent neutrophils may limit the procoagulant and/or inflammatory impact of these cells.

Pre-clinical evidence for an anti-tumor activity of defibrotide, a DNA-based, endothelium stabilizing drug

2007 ◽  
Vol 25 (18_suppl) ◽  
pp. 14144-14144
Author(s):  
C. Echart ◽  
M. Iacobelli ◽  
P. Richardson ◽  
C. Mitsiades ◽  
T. Ignoni ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Tumor Cells ◽  
Degradation Products ◽  
Microvascular Endothelial Cells ◽  
Human Gastric Cancer ◽  
Western Blots ◽  
Microvascular Endothelial ◽  
Anti Tumor Activity

14144 Background: Defibrotide (DF) is a mixture of polydeoxyribonucleotides with anti-thrombotic activity. Next to endothelium stabilization, recent data suggest anti-neoplastic properties of DF modulating interactions of tumor cells with their microenvironment. We investigated whether DF regulates expression and activity of heparanase, an enzyme critically involved in breaking down extracellular barriers and releasing growth factors linked to tumor invasion and angiogenesis. Methods: Heparanase expression was tested by RT-PCR and flow cytometry with multiple myeloma (MM) and microvascular endothelial cells. Heparanase activity was measured in cellular extracts with a heparan-degrading enzymatic assay. Serum degradation products of DF were identified by SEC-HPLC. The anti-angiogenic potential of DF was tested in vitro using a kit with human microvascular endothelial cells forming tubes across a layer of fibroblasts. In vivo, DF was tested in the dorsal skin-fold chamber assay in mice after inoculation of human gastric cancer cells. Proliferation was assessed by trypan blue exclusion. Results: We demonstrate a striking downregulation of expression and enzymatic activity of heparanase in endothelial as well as MM cells. In contrast, the degradation products of DF failed to exert any biological activity, suggesting that the intact mixture of deoxyoligonucleotides is responsible for the anti-tumor effect. We could also show that DF prevents (tumor) angiogenesis in vitro and in vivo. Western blots suggest that DF reduces phosphorylation-activation of p70S6 kinase, a key target in the mTOR pathway linked to angiogenesis. In addition, DF does not influence proliferation of vascular or tumor cells, rather acts via selective inhibition of tube formation of endothelial cells. Conclusion: In the present report we provide evidence for an anti-tumor activity of DF. DF inhibits (tumor) vessel formation and heparanase activity, and thus should be considered as an anti-cancer agent. [Table: see text]

scholarly journals Diabetes-related sex differences in the brain endothelin system following ischemia in vivo and in human brain endothelial cells in vitro

2020 ◽  
Vol 98 (9) ◽  
pp. 587-595 ◽  
Author(s):  
Yasir Abdul ◽  
Weiguo Li ◽  
Juan D. Vargas ◽  
Emily Grant ◽  
Lianying He ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Sex Differences ◽  
Cell Types ◽  
Diabetic Rats ◽  
Receptor Subtype ◽  
Endothelin System ◽  
Eta Receptor ◽  
The Brain

The endothelin (ET) system has been implicated to contribute to the pathophysiology of cognitive impairment and stroke in experimental diabetes. Our goals were to test the hypotheses that (1) circulating and (or) periinfarct ET-1 levels are elevated after stroke in both sexes and this increase is greater in diabetes, (2) ET receptors are differentially regulated in the diabetic brain, (3) brain microvascular endothelial cells (BMVEC) of female and male origin express the ETA receptor subtype, and (4) diabetes- and stroke-mimicking conditions increase ET-1 levels in BMVECs of both sexes. Control and diabetic rats were randomized to sham or stroke surgery. BMVECs of male (hBEC5i) and female (hCMEC/D3) origin, cultured under normal and diabetes-mimicking conditions, were exposed to normoxia or hypoxia. Circulating ET-1 levels were higher in diabetic animals and this was more pronounced in the male cohort. Stroke did not further increase plasma ET-1. Tissue ET-1 levels were increased after stroke only in males, whereas periinfarct ET-1 increased in both control and diabetic females. Male BMVECs secreted more ET-1 than female cells and hypoxia increased ET-1 levels in both cell types. There was sexually dimorphic regulation of ET receptors in both tissue and cell culture samples. There are sex differences in the stroke- and diabetes-mediated changes in the brain ET system at the endothelial and tissue levels.

scholarly journals miR-98 reduces endothelial dysfunction by protecting blood–brain barrier (BBB) and improves neurological outcomes in mouse ischemia/reperfusion stroke model

2019 ◽  
Vol 40 (10) ◽  
pp. 1953-1965 ◽  
Author(s):  
David L Bernstein ◽  
Viviana Zuluaga-Ramirez ◽  
Sachin Gajghate ◽  
Nancy L Reichenbach ◽  
Boris Polyak ◽  
...  
Keyword(s):  
Blood Brain Barrier ◽  
Ischemia Reperfusion ◽  
Glucose Deprivation ◽  
Brain Barrier ◽  
Inflammatory Factors ◽  
Brain Endothelium ◽  
Blood Brain ◽  
The Brain

Most neurological diseases, including stroke, lead to some degree of blood–brain barrier (BBB) dysfunction. A significant portion of BBB injury is caused by inflammation, due to pro-inflammatory factors produced in the brain, and by leukocyte engagement of the brain endothelium. Recently, microRNAs (miRNAs) have appeared as major regulators of inflammation-induced changes to gene expression in the microvascular endothelial cells (BMVEC) that comprise the BBB. However, miRNAs’ role during cerebral ischemia/reperfusion is still underexplored. Endothelial levels of miR-98 were significantly altered following ischemia/reperfusion insults, both in vivo and in vitro, transient middle cerebral artery occlusion (tMCAO), and oxygen–glucose deprivation (OGD), respectively. Overexpression of miR-98 reduced the mouse’s infarct size after tMCAO. Further, miR-98 lessened infiltration of proinflammatory Ly6CHI leukocytes into the brain following stroke and diminished the prevalence of M1 (activated) microglia within the impacted area. miR-98 attenuated BBB permeability, as demonstrated by changes to fluorescently-labeled dextran penetration in vivo and improved transendothelial electrical resistance (TEER) in vitro. Treatment with miR-98 improved significantly the locomotor impairment. Our study provides identification and functional assessment of miRNAs in brain endothelium and lays the groundwork for improving therapeutic approaches for patients suffering from ischemic attacks.

scholarly journals Studies in vitro on the uptake and degradation of sodium hyaluronate in rat liver endothelial cells

1984 ◽  
Vol 223 (3) ◽  
pp. 617-626 ◽  
Author(s):  
B Smedsrød ◽  
H Pertoft ◽  
S Eriksson ◽  
J R E Fraser ◽  
T C Laurent
Keyword(s):  
Endothelial Cells ◽  
Rat Liver ◽  
Degradation Products ◽  
Binding Capacity ◽  
Primary Cultures ◽  
Sodium Hyaluronate ◽  
Physiological Concentration ◽  
Liver Endothelial Cells

Rat liver endothelial cells in primary cultures at 7 degrees C bind radioactively labelled sodium hyaluronate (HA; Mr 400 000) specifically and with high affinity (Kd = 6 × 10(-11) M). Maximal binding capacity is approx. 10(4) molecules per cell. Inhibition experiments with unlabelled HA and oligosaccharides from HA indicate that each molecule is bound by several receptors acting co-operatively and that the single receptor recognizes a tetra- or hexa-saccharide sequence of the polysaccharide. At 37 degrees C the liver endothelial cells endocytose the HA. The process combines the features of a receptor-mediated and a fluid-phase endocytosis. The rate of internalization does not show any saturation with increasing HA concentration, but is approximately proportional to the polysaccharide concentration at and above the physiological concentration. At 50 micrograms of free HA/l each liver endothelial cell accumulates 0.1 fg of the polysaccharide/min. Fluorescent HA accumulates in perinuclear granules, presumably lysosomes. Degradation products from HA appear in the medium about 30 min after addition of the polysaccharide to the cultures. The radioactivity from HA containing N-[3H]acetyl groups or 14C in the sugar rings is recovered mainly as [3H]acetate and [14C]acetate respectively. Estimations of the capacity of liver endothelial cells to internalize and degrade HA in vitro indicate that these cells may be primarily responsible for the clearance of HA from human blood in vivo.

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