scholarly journals On the shuttling across the blood-brain barrier via tubules formation: mechanism and cargo avidity bias

2020 ◽  
Author(s):  
Xiaohe Tian ◽  
Diana Moreira Leite ◽  
Edoardo Scarpa ◽  
Sophie Nyberg ◽  
Gavin Fullstone ◽  
...  
Keyword(s):  
Blood Brain Barrier ◽  
Density Lipoprotein ◽  
Brain Barrier ◽  
Receptor Interaction ◽  
High Avidity ◽  
Waste Products ◽  
Blood Brain ◽  
The Brain

The blood-brain barrier is made of polarised brain endothelial cells (BECs) phenotypically conditioned by the central nervous system (CNS). Transport across BECs is of paramount importance for nutrient uptake as well as to rid the brain of waste products. Nevertheless, currently we do not understand how large macromolecular cargo shuttles across and how BECs discriminate between the brain-bound and own nutrients. Here, we study the low-density lipoprotein receptor-related protein 1 (LRP1) an essential regulator of BEC transport, and show that it is associated with endocytic effectors, endo-lysosomal compartments as well as syndapin-2, a member of the Bin/Amphiphysin/Rvs (BAR) domain superfamily known to stabilise tubular carriers. We employed synthetic self-assembled vesicles, polymersomes, as a multivalent system with tunable avidity as a tool to investigate the mechanism of transport across BECs. We used a combination of conventional and super-resolution microscopy, both in vivo and in vitro, accompanied with biophysical modelling of transport kinetics and membrane-bound interactions. Our results demonstrate that the avidity of the ligand-receptor interaction (the overall cargo binding energy) determines the mechanism of sorting during the early stages of endocytosis and consequent trafficking. We show that high avidity cargo biases the LRP1 towards internalisation and fast degradation in BECs, while mid avidity augments the formation of syndapin-2 stabilised tubular carriers and promotes fast shuttling across BECs. Thus, we map out a very detailed mechanism where clathrin, actin, syndapin-2, dynamin and SNARE act synergistically to enable fast shuttling across BECs.

scholarly journals On the shuttling across the blood-brain barrier via tubule formation: Mechanism and cargo avidity bias

2020 ◽  
Vol 6 (48) ◽  
pp. eabc4397 ◽  
Author(s):  
Xiaohe Tian ◽  
Diana M. Leite ◽  
Edoardo Scarpa ◽  
Sophie Nyberg ◽  
Gavin Fullstone ◽  
...  
Keyword(s):  
Blood Brain Barrier ◽  
Density Lipoprotein ◽  
Brain Barrier ◽  
High Avidity ◽  
Biophysical Modeling ◽  
Tubule Formation ◽  
Waste Products ◽  
Blood Brain

The blood-brain barrier is made of polarized brain endothelial cells (BECs) phenotypically conditioned by the central nervous system (CNS). Although transport across BECs is of paramount importance for nutrient uptake as well as ridding the brain of waste products, the intracellular sorting mechanisms that regulate successful receptor-mediated transcytosis in BECs remain to be elucidated. Here, we used a synthetic multivalent system with tunable avidity to the low-density lipoprotein receptor–related protein 1 (LRP1) to investigate the mechanisms of transport across BECs. We used a combination of conventional and super-resolution microscopy, both in vivo and in vitro, accompanied with biophysical modeling of transport kinetics and membrane-bound interactions to elucidate the role of membrane-sculpting protein syndapin-2 on fast transport via tubule formation. We show that high-avidity cargo biases the LRP1 toward internalization associated with fast degradation, while mid-avidity augments the formation of syndapin-2 tubular carriers promoting a fast shuttling across.

scholarly journals Lysozyme transport to the brain by liposomes

2018 ◽  
Vol 1 (2) ◽  
pp. 146-161 ◽  
Author(s):  
Mirjam M Nordling-David ◽  
Elior Rachamin ◽  
Etty Grad ◽  
Gershon Golomb
Keyword(s):  
Blood Brain Barrier ◽  
White Blood Cells ◽  
Brain Barrier ◽  
Immunofluorescent Staining ◽  
Phagocytic Cells ◽  
Blood Brain ◽  
The Brain ◽  
Positively Charged

Delivery of drugs into the brain is limited due to poor penetrability of many drugs via the blood-brain barrier. Previous studies have shown that the brain is kept under close surveillance by the immune system, implying that circulating phagocytic cells, such as neutrophils and monocytes, are crossing the blood-brain barrier. We hypothesized that charged liposomes could be transported to the brain following their phagocytosis by circulating monocytes. In this work, we investigated the capacity of circulating monocytes to be exploited as a drug delivery system following IV administration of nano-sized, positively fluorescently labeled liposomes containing the protein lysozyme. Negatively charged fluorescently labeled liposomes were used for comparison. By using a modified thin-film hydration technique, the desired properties of the liposomal formulations were achieved including size, polydispersity index, high drug concentration, and stability. In vitro results showed a significant time-dependent uptake of positively charged liposomes by RAW264.7 cells. In vivo results revealed that circulating white blood cells (mainly monocytes) contained high levels of fluorescently labeled liposomes. Screening of brain sections using confocal microscopy uncovered that a substantial amount of fluorescently labeled liposomes, in contrast to the fluorescent markers in solution, was transported into the brain. In addition, anti-CD68 immunofluorescent staining of brain sections demonstrated co-localization of positively charged liposomes and macrophages in different brain sections. Furthermore, significantly higher levels of lysozyme were detected in brain lysates from rats treated with positively charged liposomes compared to rats treated with lysozyme solution. Taken together this confirms our hypothesis that the designed liposomes were transported to the brain following their phagocytosis by circulating monocytes.

Lipid Nanoformulations in the Treatment of Neuropsychiatric Diseases: An Approach to Overcome the Blood Brain Barrier

2020 ◽  
Vol 21 (9) ◽  
pp. 674-684 ◽  
Author(s):  
Saleha Rehman ◽  
Bushra Nabi ◽  
Faheem Hyder Pottoo ◽  
Sanjula Baboota ◽  
Javed Ali
Keyword(s):  
Blood Brain Barrier ◽  
Water Solubility ◽  
Oral Absorption ◽  
Brain Barrier ◽  
Therapeutic Drug ◽  
Blood Brain ◽  
Neuropsychiatric Diseases ◽  
The Brain

Background: Neuropsychiatric diseases primarily characterized by dementia stand third in the global list of diseases causing disability. The poor water solubility, erratic oral absorption, low bioavailability, poor intestinal absorption, and the impeding action of the blood-brain barrier (BBB) are the major factors limiting the therapeutic feasibility of the antipsychotics. Only a small percentage of antipsychotics reaches the therapeutic target site, which warrants administration of high doses, consequently leading to unwanted side-effects. Hence the main struggle for the effective treatment of neuropsychiatric diseases occurs “at the gates” of the brain, which can be mitigated with the use of a nanotechnology-based platform. Methods: The goal of this review is to undertake a comprehensive study about the role of lipid nanoformulations in facilitating the delivery of antipsychotics across BBB along with the available in vitro and in vivo evidence. Results: Lipid nanoformulations have attained great popularity for the delivery of therapeutics into the brain. Their nanosize helps in overcoming the biological barriers, thereby providing easy BBB translocation of the drugs. Besides, they offer numerous advantages like controlled and targeted drug release, minimizing drug efflux, long storage stability, augmented bioavailability, and reduced adverse drug effects to attain an optimal therapeutic drug concentration in the brain. Moreover, employing alternative routes of administration has also shown promising results. Conclusion: Thus, it can be concluded that the lipid nanoformulations bear immense potential in overcoming the challenges associated with the treatment of neuropsychiatric disorders. However, the area warrants further clinical studies to ensure their commercialization, which could revolutionize the treatment of neuropsychiatric diseases in the coming decades.

scholarly journals Overcoming the Blood-Brain Barrier: Functionalised Chitosan Nanocarriers

Pharmaceutics ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 1013 ◽  
Author(s):  
Anna E. Caprifico ◽  
Peter J. S. Foot ◽  
Elena Polycarpou ◽  
Gianpiero Calabrese
Keyword(s):  
Blood Brain Barrier ◽  
Chemical Properties ◽  
Brain Barrier ◽  
Hydroxyl Groups ◽  
Blood Brain ◽  
The Brain ◽  
Major Impediment ◽  
And Chemical Properties

The major impediment to the delivery of therapeutics to the brain is the presence of the blood-brain barrier (BBB). The BBB allows for the entrance of essential nutrients while excluding harmful substances, including most therapeutic agents; hence, brain disorders, especially tumours, are very difficult to treat. Chitosan is a well-researched polymer that offers advantageous biological and chemical properties, such as mucoadhesion and the ease of functionalisation. Chitosan-based nanocarriers (CsNCs) establish ionic interactions with the endothelial cells, facilitating the crossing of drugs through the BBB by adsorptive mediated transcytosis. This process is further enhanced by modifications of the structure of chitosan, owing to the presence of reactive amino and hydroxyl groups. Finally, by permanently binding ligands or molecules, such as antibodies or lipids, CsNCs have showed a boosted passage through the BBB, in both in vivo and in vitro studies which will be discussed in this review.

scholarly journals Nanoparticles Based on Quaternary Ammonium Chitosan-methyl-β-cyclodextrin Conjugate for the Neuropeptide Dalargin Delivery to the Central Nervous System: An In Vitro Study

Pharmaceutics ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 5
Author(s):  
Chiara Migone ◽  
Letizia Mattii ◽  
Martina Giannasi ◽  
Stefania Moscato ◽  
Andrea Cesari ◽  
...  
Keyword(s):  
Blood Brain Barrier ◽  
Quaternary Ammonium ◽  
Oral Absorption ◽  
In Vitro Study ◽  
Brain Barrier ◽  
Mucosal Barrier ◽  
Blood Brain ◽  
The Brain

Peptide oral administration is a hard goal to reach, especially if the brain is the target site. The purpose of the present study was to set up a vehicle apt to promote oral absorption of the neuropeptide dalargin (DAL), allowing it to cross the intestinal mucosal barrier, resist enzymatic degradation, and transport drugs to the brain after crossing the blood–brain barrier. Therefore, a chitosan quaternary ammonium derivative was synthesized and conjugated with methyl-β-cyclodextrin to prepare DAL-medicated nanoparticles (DAL-NP). DAL-NP particle size was 227.7 nm, zeta potential +8.60 mV, encapsulation efficiency 89%. DAL-NP protected DAL from degradation by chymotrypsin or pancreatin and tripled DAL degradation time compared to non-encapsulated DAL. Use of DAL-NP was safe for either Caco-2 or bEnd.3 cells, with the latter selected as a blood–brain barrier model. DAL-NP could also cross either the Caco-2 or bEnd.3 monolayer by the transepithelial route. The results suggest a potential DAL-NP ability to transport to the brain a DAL dose fraction administered orally, although in vivo experiments will be needed to confirm the present data obtained in vitro.

Organic Cation Transporters are Involved in Fluoxetine Transport Across the Blood-Brain Barrier in Vivo and in Vitro

2021 ◽  
Vol 18 ◽  
Author(s):  
Min Wang ◽  
Yingying Sun ◽  
Bingying Hu ◽  
Zhisheng He ◽  
Shanshan Chen ◽  
...  
Keyword(s):  
Blood Brain Barrier ◽  
Cellular Uptake ◽  
Organic Cation ◽  
Brain Barrier ◽  
Organic Cation Transporters ◽  
Cellular Accumulation ◽  
Blood Brain ◽  
The Brain

Background : The research and development of drugs for the treatment of central nervous system diseases faces many challenges at present. One of the most important questions to be answered is, how does the drug cross the blood-brain barrier to get to the target site for pharmacological action. Fluoxetine is widely used in clinical antidepressant therapy. However, the mechanism by which fluoxetine passes through the BBB also remains unclear. Under physiological pH conditions, fluoxetine is an organic cation with a relatively small molecular weight (<500), which is in line with the substrate characteristics of organic cation transporters (OCTs). Therefore, this study aimed to investigate the interaction of fluoxetine with OCTs at the BBB and BBB-associated efflux transporters. This is of great significance for fluoxetine to better treat depression. Moreover, it can provide a theoretical basis for clinical drug combinations. Methods: In vitro BBB model was developed using human brain microvascular endothelial cells (hCMEC/D3), and the cellular accumulation was tested in the presence or absence of transporter inhibitors. In addition, an in vivo trial was performed in rats to investigate the effect of OCTs on the distribution of fluoxetine in the brain tissue. Fluoxetine concentration was determined by a validated UPLC-MS/MS method. Results: The results showed that amantadine (an OCT1/2 inhibitor) and prazosin (an OCT1/3 inhibitor) significantly decreased the cellular accumulation of fluoxetine (P <.001). Moreover, we found that N-methylnicotinamide (an OCT2 inhibitor) significantly inhibited the cellular uptake of 100 and 500 ng/mL fluoxetine (P <.01 and P <.05 respectively). In contrast, corticosterone (an OCT3 inhibitor) only significantly inhibited the cellular uptake of 1000 ng/mL fluoxetine (P <.05). The P-glycoprotein (P-gp) inhibitor, verapamil, and the multidrug resistance resistance-associated proteins (MRPs) inhibitor, MK571, significantly decreased the cellular uptake of fluoxetine. However, intracellular accumulation of fluoxetine was not significantly changed when fluoxetine was incubated with the breast cancer resistance protein (BCRP) inhibitor Ko143. Furthermore, in vivo experiments proved that corticosterone and prazosin significantly inhibited the brain-plasma ratio of fluoxetine at 5.5 h and 12 h, respectively. Conclusion: OCTs might play a significant role in the transport of fluoxetine across the BBB. In addition, P-gp, BCRP, and MRPs seemed not to mediate the efflux transport of fluoxetine.

scholarly journals A blood–brain barrier overview on structure, function, impairment, and biomarkers of integrity

2020 ◽  
Vol 17 (1) ◽  
Author(s):  
Hossam Kadry ◽  
Behnam Noorani ◽  
Luca Cucullo
Keyword(s):  
Blood Brain Barrier ◽  
Structural Integrity ◽  
Critical Role ◽  
Brain Barrier ◽  
Clinical Aspects ◽  
Advantages And Disadvantages ◽  
Blood Brain ◽  
The Brain

AbstractThe blood–brain barrier is playing a critical role in controlling the influx and efflux of biological substances essential for the brain’s metabolic activity as well as neuronal function. Thus, the functional and structural integrity of the BBB is pivotal to maintain the homeostasis of the brain microenvironment. The different cells and structures contributing to developing this barrier are summarized along with the different functions that BBB plays at the brain–blood interface. We also explained the role of shear stress in maintaining BBB integrity. Furthermore, we elaborated on the clinical aspects that correlate between BBB disruption and different neurological and pathological conditions. Finally, we discussed several biomarkers that can help to assess the BBB permeability and integrity in-vitro or in-vivo and briefly explain their advantages and disadvantages.

Drug transport to the brain: comparison between in vitro and in vivo models of the blood-brain barrier

1995 ◽  
Vol 3 (6) ◽  
pp. 357-365 ◽  
Author(s):  
M.P. Dehouck ◽  
B. Dehouck ◽  
C. Schluep ◽  
M. Lemaire ◽  
R. Cecchelli
Keyword(s):  
Blood Brain Barrier ◽  
Drug Transport ◽  
Brain Barrier ◽  
In Vivo Models ◽  
Blood Brain ◽  
The Brain

scholarly journals A New Function for the LDL Receptor: Transcytosis of LDL across the Blood–Brain Barrier

1997 ◽  
Vol 138 (4) ◽  
pp. 877-889 ◽  
Author(s):  
Bénédicte Dehouck ◽  
Laurence Fenart ◽  
Marie-Pierre Dehouck ◽  
Annick Pierce ◽  
Gérard Torpier ◽  
...  
Keyword(s):  
Blood Brain Barrier ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Cytoplasmic Domain ◽  
Brain Barrier ◽  
Classical Pathway ◽  
Brain Capillary ◽  
Blood Brain ◽  
The Brain

Lipoprotein transport across the blood–brain barrier (BBB) is of critical importance for the delivery of essential lipids to the brain cells. The occurrence of a low density lipoprotein (LDL) receptor on the BBB has recently been demonstrated. To examine further the function of this receptor, we have shown using an in vitro model of the BBB, that in contrast to acetylated LDL, which does not cross the BBB, LDL is specifically transcytosed across the monolayer. The C7 monoclonal antibody, known to interact with the LDL receptor-binding domain, totally blocked the transcytosis of LDL, suggesting that the transcytosis is mediated by the receptor. Furthermore, we have shown that cholesterol-depleted astrocytes upregulate the expression of the LDL receptor at the BBB. Under these conditions, we observed that the LDL transcytosis parallels the increase in the LDL receptor, indicating once more that the LDL is transcytosed by a receptor-mediated mechanism. The nondegradation of the LDL during the transcytosis indicates that the transcytotic pathway in brain capillary endothelial cells is different from the LDL receptor classical pathway. The switch between a recycling receptor to a transcytotic receptor cannot be explained by a modification of the internalization signals of the cytoplasmic domain of the receptor, since we have shown that LDL receptor messengers in growing brain capillary ECs (recycling LDL receptor) or differentiated cells (transcytotic receptor) are 100% identical, but we cannot exclude posttranslational modifications of the cytoplasmic domain, as demonstrated for the polymeric immunoglobulin receptor. Preliminary studies suggest that caveolae are likely to be involved in the potential transport of LDL from the blood to the brain.

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