scholarly journals Functional Expression of Choline Transporters in the Blood–Brain Barrier

Nutrients ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 2265 ◽  
Author(s):  
Masato Inazu

Cholinergic neurons in the central nervous system play a vital role in higher brain functions, such as learning and memory. Choline is essential for the synthesis of the neurotransmitter acetylcholine by cholinergic neurons. The synthesis and metabolism of acetylcholine are important mechanisms for regulating neuronal activity. Choline is a positively charged quaternary ammonium compound that requires transporters to pass through the plasma membrane. Currently, there are three groups of choline transporters with different characteristics, such as affinity for choline, tissue distribution, and sodium dependence. They include (I) polyspecific organic cation transporters (OCT1-3: SLC22A1-3) with a low affinity for choline, (II) high-affinity choline transporter 1 (CHT1: SLC5A7), and (III) choline transporter-like proteins (CTL1-5: SLC44A1-5). Brain microvascular endothelial cells, which comprise part of the blood–brain barrier, take up extracellular choline via intermediate-affinity choline transporter-like protein 1 (CTL1) and low-affinity CTL2 transporters. CTL2 is responsible for excreting a high concentration of choline taken up by the brain microvascular endothelial cells on the brain side of the blood–brain barrier. CTL2 is also highly expressed in mitochondria and may be involved in the oxidative pathway of choline metabolism. Therefore, CTL1- and CTL2-mediated choline transport to the brain through the blood–brain barrier plays an essential role in various functions of the central nervous system by acting as the rate-limiting step of cholinergic neuronal activity.

Author(s):  
Lorena Gárate-Vélez ◽  
Claudia Escudero-Lourdes ◽  
Daniela Salado-Leza ◽  
Armando González-Sánchez ◽  
Ildemar Alvarado-Morales ◽  
...  

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.


1960 ◽  
Vol 198 (6) ◽  
pp. 1296-1298 ◽  
Author(s):  
Benedict Cassen ◽  
Richard Neff

Experimental evidence is obtained that, coincident with a state of not too severe concussion, the blood-brain barrier system becomes more permeable to phosphate ions. The permeability returns to normal when the animal recovers and shows normal activity. Arguments are presented in favor of the hypothesis that dysfunction of the central nervous system during concussion is related to a disturbed electrolyte balance in the fluids of the brain caused by a piezochemical disturbance of the blood-brain barrier membranes (presumably the astropods of the astrocytic cells).


2021 ◽  
Author(s):  
Sheng Yang ◽  
Yufei Huang ◽  
Yonghong Shi ◽  
Xuebing Bai ◽  
Ping Yang ◽  
...  

Tembusu Virus (TMUV) is an emerging and re-emerging zoonotic pathogen that adversely affects poultry industry in recent years. TMUV disease is characterized by nonsuppurative encephalitis in ducklings. The duckling infection model was established to study the mechanism of TMUV crossing the blood-brain barrier (BBB) into the central nervous system (CNS). Here, we showed that no obvious clinical symptoms and enhancement of BBB permeability occurred at the early stage of infection (3∼5 dpi). While simultaneously virus particles were observed by transmission electron microscopy in the brain, inducing the accumulation of inflammatory cytokines. Neurological symptoms and disruption of BBB appeared at the intermediate stage of infection (7∼9 dpi). It was confirmed that TMUV could survive and propagate in brain microvascular endothelial cells (BMECs), but did not affect the permeability of BBB in vivo and in vitro at an early date. In conclusion, TMUV enters the CNS then causes encephalitis, and finally destruct the BBB, which may be due to the direct effect of TMUV on BMECs and the subsequent response of “inflammatory storm”. IMPORTANCE The TMUV disease has caused huge losses to the poultry industry in Asia, which is potentially harmful to public health. Neurological symptoms and their sequelae are the main characters of this disease. However, the mechanism of how this virus enters the brain and causes encephalitis is unclear. In this study, we confirmed that the virus entered the CNS and then massively destroyed BBB and the BBB damage was closely associated with the subsequent outbreak of inflammation. TMUV may enter the CNS through the transcellular and “Trojan horse” pathways. These findings can fill the knowledge gap in the pathogenesis of TMUV-infected poultry and be benefit for the treatment of TMUV disease. What’s more, TMUV is a representative to study the infection of avian flavivirus. Therefore, our studies have significances both for understanding of the full scope of mechanisms of TMUV and other flavivirus infection, and conceivably, for therapeutics.


eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Gabriela C Olivera ◽  
Emily C Ross ◽  
Christiane Peuckert ◽  
Antonio Barragan

The cellular barriers of the central nervous system proficiently protect the brain parenchyma from infectious insults. Yet, the single-celled parasite Toxoplasma gondii commonly causes latent cerebral infection in humans and other vertebrates. Here, we addressed the role of the cerebral vasculature in the passage of T. gondii to the brain parenchyma. Shortly after inoculation in mice, parasites mainly localized to cortical capillaries, in preference over post-capillary venules, cortical arterioles or meningeal and choroidal vessels. Early invasion to the parenchyma (days 1-5) occurred in absence of a measurable increase in blood-brain barrier (BBB) permeability, perivascular leukocyte cuffs or hemorrhage. However, sparse focalized permeability elevations were detected adjacently to replicative parasite foci. Further, T. gondii triggered inflammatory responses in cortical microvessels and endothelium. Pro- and anti-inflammatory treatments of mice with LPS and hydrocortisone, respectively, impacted BBB permeability and parasite loads in the brain parenchyma. Finally, pharmacological inhibition or Cre/loxP conditional knockout of endothelial focal adhesion kinase (FAK), a BBB intercellular junction regulator, facilitated parasite translocation to the brain parenchyma. The data reveal that the initial passage of T. gondii to the central nervous system occurs principally across cortical capillaries. The integrity of the microvascular BBB restricts parasite transit, which conversely is exacerbated by the inflammatory response.


Author(s):  
S Dingezweni

The blood–brain barrier (BBB) is a dynamic barrier essential for central nervous system interstitial fluid separation from circulating blood. This dynamic separation ensures maintenance of neuronal microenvironment homeostasis against that of the everchanging in solutes and toxin concentration in circulating blood. The blood–brain barrier structure is complex, it has multiple contributors, such as specialised blood microvascular endothelium, neurons, astrocytes and pericytes. Transfer of essential nutrients to the brain and waste products from the brain to circulating blood is tightly regulated and facilitated by a large surface area and specialised transport systems. It is not only the physical characteristics of the barrier that assist in maintenance of neuronal microenvironment, biochemical substances and the high trans endothelial electrical resistance also play a major role. Circumventricular organs are those parts of the central nervous system lacking the blood–brain barrier. These are essential for optimum central nervous system interaction with circulating blood directly or using neurotransmitters. Primary or secondary central nervous system pathological states, such as infective and noninfective causes, directly or indirectly induce biochemical mediators that may disrupt and alter blood–brain barrier structure and function. Understanding of the blood–brain barrier anatomy and physiology assists in developing treatment methods to overcome degenerative and pathological states negatively affecting the central nervous system.


2020 ◽  
Vol 4 (2) ◽  
pp. 053-062
Author(s):  
Dutta Rajib

Blood vessels that supply and feed the central nervous system (CNS) possess unique and exclusive properties, named as blood–brain barrier (BBB). It is responsible for tight regulation of the movement of ions, molecules, and cells between the blood and the brain thereby maintaining controlled chemical composition of the neuronal milieu required for appropriate functioning. It also protects the neural tissue from toxic plasma components, blood cells and pathogens from entering the brain. In this review the importance of BBB and its disruption causing brain pathology and progression to different neurological diseases like Alzheimer’s disease (AD), Parkinson’s disease (PD), Amyotrophic lateral sclerosis (ALS), Huntington’s disease (HD) etc. will be discussed.


2004 ◽  
Vol 72 (9) ◽  
pp. 4985-4995 ◽  
Author(s):  
Yun C. Chang ◽  
Monique F. Stins ◽  
Michael J. McCaffery ◽  
Georgina F. Miller ◽  
Dan R. Pare ◽  
...  

ABSTRACT Cryptococcal meningoencephalitis develops as a result of hematogenous dissemination of inhaled Cryptococcus neoformans from the lung to the brain. The mechanism(s) by which C. neoformans crosses the blood-brain barrier (BBB) is a key unresolved issue in cryptococcosis. We used both an in vivo mouse model and an in vitro model of the human BBB to investigate the cryptococcal association with and traversal of the BBB. Exposure of human brain microvascular endothelial cells (HBMEC) to C. neoformans triggered the formation of microvillus-like membrane protrusions within 15 to 30 min. Yeast cells of C. neoformans adhered to and were internalized by the HBMEC, and they crossed the HBMEC monolayers via a transcellular pathway without affecting the monolayer integrity. The histopathology of mouse brains obtained after intravenous injection of C. neoformans showed that the yeast cells either were associated with endothelial cells or escaped from the brain capillary vessels into the neuropil by 3 h. C. neoformans was found in the brain parenchyma away from the vessels by 22 h. Association of C. neoformans with the choroid plexus, however, was not detected during up to 10 days of observation. Our findings indicate that C. neoformans cells invade the central nervous system by transcellular crossing of the endothelium of the BBB.


2019 ◽  
Author(s):  
Brett A. Eyford ◽  
Chaahat S.B. Singh ◽  
Thomas Abraham ◽  
Lonna Munro ◽  
Kyung Bok Choi ◽  
...  

AbstractThe blood-brain barrier (BBB), hinders the distribution of therapeutics, intended for treatment of diseases of the brain. A twelve-amino acid peptide, termed MTfp, was derived from MTf, and retains the ability to cross the BBB intact and ferry cargo into intacellular organelles within neurons, glia and microglia in the brain. A novel MTfp-siRNA peptide-oligonucleotide conjugate (POC), directed against NOX4, a gene known to potentiate ischemic stroke, was chemically synthesized. The MTfp-NOX4 siRNA POC traversed the BBB, resulting in the knockdown of NOX4 expression in the brain. Following induction of ischemic stroke, animals treated with the POC exhibited significantly smaller infarcts; accompanied by significant protection against neurological deterioration and improved recovery. The data demonstrates that the MTfp portion, of this novel POC, can facilitate BBB transcytosis; where the siRNA moiety can elicit effective therapeutic knockdown of a gene associated with a disease of the central nervous system (CNS). This is a general platform to transport therapeutics to the CNS and thereby, offers new avenues for potential treatments of neuropathologies that are currently refractory to existing therapies.


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