248 research outputs found
The Brain Microvascular Endothelium Supports T Cell Proliferation and Has Potential for Alloantigen Presentation
Endothelial cells (EC) form the inner lining of blood vessels and are positioned between circulating lymphocytes and tissues. Hypotheses have formed that EC may act as antigen presenting cells based on the intimate interactions with T cells, which are seen in diseases like multiple sclerosis, cerebral malaria (CM) and viral neuropathologies. Here, we investigated how human brain microvascular EC (HBEC) interact with and support the proliferation of T cells. We found HBEC to express MHC II, CD40 and ICOSL, key molecules for antigen presentation and co-stimulation and to take up fluorescently labeled antigens via macropinocytosis. In co-cultures, we showed that HBEC support and promote the proliferation of CD4+ and CD8+ T cells, which both are key in CM pathogenesis, particularly following T cell receptor activation and co-stimulation. Our findings provide novel evidence that HBEC can trigger T cell activation, thereby providing a novel mechanism for neuroimmunological complications of infectious diseases. © 2013 Wheway et al
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Modulation of blood-brain barrier permeability by neutrophils: in vitro and in vivo studies
The blood-brain barrier (BBB) restricts solute permeability across healthy cerebral endothelial cells. However, during inflammation, permeability is increased and can lead to deleterious cerebral edema. Neutrophils are early cellular participants in acute inflammation, but their effect on BBB permeability is unclear. To study this, neutrophils were applied in a resting and activated state to in vitro and in vivo models of the BBB. In vitro, human neutrophils (5 × 106/ml) were activated with tumor necrosis factor (100U/ml) and leukotriene B4 (10-7mol/l). Untreated neutrophils reduced permeability across the human brain endothelial cell line hCMEC/D3. Activated neutrophils returned permeability to baseline, an effect blocked by the reactive oxygen scavengers superoxide dismutase (10U/ml) and catalase (1000U/ml). In vivo, human neutrophils (2.5 × 105 in 4μl) were injected into the striatum of anesthetized juvenile Wistar rats, and BBB permeability measured 30 minutes later. This was compared to control injections (4μl) of vehicle (0.9% saline) and arachidonic acid (10-3mol/l). The injection generated a small hematoma around the injection tract (<3μl). Untreated neutrophils induced significantly lower permeability in their vicinity than activated neutrophils, with a trend to lowered permeability compared to the vehicle control. Neither untreated nor activated neutrophils induced permeability increases, while arachidonic acid increased permeability as a positive control. This study further delineates the effect of neutrophils on the BBB, and demonstrates that resting neutrophils induce acute reductions in permeability while activated neutrophils have a neutral effect. The in vivo model reiterates some aspects of acute intracerebral hemorrhage
Role of KCNMA1 gene in breast cancer invasion and metastasis to brain
International audienceBACKGROUND: The prognosis for patients with breast tumor metastases to brain is extremely poor. Identification of prognostic molecular markers of the metastatic process is critical for designing therapeutic modalities for reducing the occurrence of metastasis. Although ubiquitously present in most human organs, large-conductance calcium- and voltage-activated potassium channel (BKCa) channels are significantly upregulated in breast cancer cells. In this study we investigated the role of KCNMA1 gene that encodes for the pore-forming alpha-subunit of BKCa channels in breast cancer metastasis and invasion. METHODS: We performed Global exon array to study the expression of KCNMA1 in metastatic breast cancer to brain, compared its expression in primary breast cancer and breast cancers metastatic to other organs, and validated the findings by RT-PCR. Immunohistochemistry was performed to study the expression and localization of BKCa channel protein in primary and metastatic breast cancer tissues and breast cancer cell lines. We performed matrigel invasion, transendothelial migration and membrane potential assays in established lines of normal breast cells (MCF-10A), non-metastatic breast cancer (MCF-7), non-brain metastatic breast cancer cells (MDA-MB-231), and brain-specific metastatic breast cancer cells (MDA-MB-361) to study whether BKCa channel inhibition attenuates breast tumor invasion and metastasis using KCNMA1 knockdown with siRNA and biochemical inhibition with Iberiotoxin (IBTX). RESULTS: The Global exon array and RT-PCR showed higher KCNMA1 expression in metastatic breast cancer in brain compared to metastatic breast cancers in other organs. Our results clearly show that metastatic breast cancer cells exhibit increased BKCa channel activity, leading to greater invasiveness and transendothelial migration, both of which could be attenuated by blocking KCNMA1. CONCLUSION: Determining the relative abundance of BKCa channel expression in breast cancer metastatic to brain and the mechanism of its action in brain metastasis will provide a unique opportunity to identify and differentiate between low grade breast tumors that are at high risk for metastasis from those at low risk for metastasis. This distinction would in turn allow for the appropriate and efficient application of effective treatments while sparing patients with low risk for metastasis from the toxic side effects of chemotherapy
Edaravone protects against methylglyoxal-induced barrier damage in human brain endothelial cells
BACKGROUND:
Elevated level of reactive carbonyl species, such as methylglyoxal, triggers carbonyl stress and activates a series of inflammatory responses leading to accelerated vascular damage. Edaravone is the active substance of a Japanese medicine, which aids neurological recovery following acute brain ischemia and subsequent cerebral infarction. Our aim was to test whether edaravone can exert a protective effect on the barrier properties of human brain endothelial cells (hCMEC/D3 cell line) treated with methylglyoxal.
METHODOLOGY:
Cell viability was monitored in real-time by impedance-based cell electronic sensing. The barrier function of the monolayer was characterized by measurement of resistance and flux of permeability markers, and visualized by immunohistochemistry for claudin-5 and β-catenin. Cell morphology was also examined by holographic phase imaging.
PRINCIPAL FINDINGS:
Methylglyoxal exerted a time- and dose-dependent toxicity on cultured human brain endothelial cells: a concentration of 600 µM resulted in about 50% toxicity, significantly reduced the integrity and increased the permeability of the barrier. The cell morphology also changed dramatically: the area of cells decreased, their optical height significantly increased. Edaravone (3 mM) provided a complete protection against the toxic effect of methylglyoxal. Co-administration of edaravone restored cell viability, barrier integrity and functions of brain endothelial cells. Similar protection was obtained by the well-known antiglycating molecule, aminoguanidine, our reference compound.
CONCLUSION:
These results indicate for the first time that edaravone is protective in carbonyl stress induced barrier damage. Our data may contribute to the development of compounds to treat brain endothelial dysfunction in carbonyl stress related diseases
Implementing flexible bronchoscopy in least developed countries according to international guidelines is feasible and sustainable: example from Phnom-Penh, Cambodia
Real-time control of distributed batteries with blockchain-enabled market export commitments
Recent years have seen a surge of interest in
distributed residential batteries for households with renewable
generation. Yet, assuring battery assets are profitable for their
owners requires a complex optimisation of the battery asset and
additional revenue sources, such as novel ways to access wholesale
energy markets. In this paper, we propose a framework in which
wholesale market bids are placed on forward energy markets
by an aggregator of distributed residential batteries that are
controlled in real time by a novel Home Energy Management
System (HEMS) control algorithm to meet the market commitments, while maximising local self-consumption. The proposed
framework consists of three stages. In the first stage, an optimal
day-ahead or intra-day scheduling of the aggregated storage
assets is computed centrally. For the second stage, a bidding
strategy is developed for wholesale energy markets. Finally, in the
third stage, a novel HEMS real-time control algorithm based on a
smart contract allows coordination of residential batteries to meet
the market commitments and maximise self-consumption of local
production. Using a case study provided by a large UK-based
energy demonstrator, we apply the framework to an aggregator
with 70 residential batteries. Experimental analysis is done using
real per minute data for demand and production. Results indicate
that the proposed approach increases the aggregator’s revenues
by 35% compared to a case without residential flexibility, and
increases the self-consumption rate of the households by a factor
of two. The robustness of the results to uncertainty, forecast
errors and to communication latency is also demonstrated
Management of emerging multidrug-resistant tuberculosis in a low-prevalence setting
AbstractMultidrug-resistant (MDR) tuberculosis (TB) is an emerging concern in communities with a low TB prevalence and a high standard of public health. Twenty-three consecutive adult MDR TB patients who were treated at our institution between 2007 and 2013 were reviewed for demographic characteristics and anti-TB treatment management, which included surgical procedures and long-term patient follow-up. This report of our experience emphasizes the need for an individualized approach as MDR TB brings mycobacterial disease management to a higher level of expertise, and for a balance to be found between international current guidelines and patient-tailored treatment strategies
Transthyretin participates in beta-amyloid transport from the brain to the liver- involvement of the low-density lipoprotein receptor-related protein 1?
Transthyretin (TTR) binds Aβ peptide, preventing its deposition and toxicity. TTR is decreased in
Alzheimer’s disease (AD) patients. Additionally, AD transgenic mice with only one copy of the TTR
gene show increased brain and plasma Aβ levels when compared to AD mice with both copies of the
gene, suggesting TTR involvement in brain Aβ efflux and/or peripheral clearance. Here we showed that
TTR promotes Aβ internalization and efflux in a human cerebral microvascular endothelial cell line,
hCMEC/D3. TTR also stimulated brain-to-blood but not blood-to-brain Aβ permeability in hCMEC/D3,
suggesting that TTR interacts directly with Aβ at the blood-brain-barrier. We also observed that TTR
crosses the monolayer of cells only in the brain-to-blood direction, as confirmed by in vivo studies,
suggesting that TTR can transport Aβ from, but not into the brain. Furthermore, TTR increased Aβ
internalization by SAHep cells and by primary hepatocytes from TTR+/+ mice when compared to
TTR−/− animals. We propose that TTR-mediated Aβ clearance is through LRP1, as lower receptor
expression was found in brains and livers of TTR−/− mice and in cells incubated without TTR. Our
results suggest that TTR acts as a carrier of Aβ at the blood-brain-barrier and liver, using LRP1
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