The blood-brain barrier (BBB) is a selective barrier and a functional gatekeeper for the central nervous system (CNS), essential for maintaining brain homeostasis. The BBB is composed of specialized ...brain endothelial cells (BECs) lining the brain capillaries. The tight junctions formed by BECs regulate paracellular transport, whereas transcellular transport is regulated by specialized transporters, pumps and receptors. Cytokine-induced neuroinflammation, such as the tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β), appear to play a role in BBB dysfunction and contribute to the progression of Alzheimer’s disease (AD) by contributing to amyloid-β (Aβ) peptide accumulation. Here, we investigated whether TNF-α and IL-1β modulate the permeability of the BBB and alter Aβ peptide transport across BECs. We used a human BBB in vitro model based on the use of brain-like endothelial cells (BLECs) obtained from endothelial cells derived from CD34+ stem cells cocultivated with brain pericytes. We demonstrated that TNF-α and IL-1β differentially induced changes in BLECs’ permeability by inducing alterations in the organization of junctional complexes as well as in transcelluar trafficking. Further, TNF-α and IL-1β act directly on BLECs by decreasing LRP1 and BCRP protein expression as well as the specific efflux of Aβ peptide. These results provide mechanisms by which CNS inflammation might modulate BBB permeability and promote Aβ peptide accumulation. A future therapeutic intervention targeting vascular inflammation at the BBB may have the therapeutic potential to slow down the progression of AD.
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•In vitro BBB does not predict permeability in vivo for highly lipophilic compounds.•In vitro BBB permeability does not account for brain tissue binding.•Glial cells could be use in ...vitro to mimic the influence of brain tissue binding.•New calculation method accounting for both BBB permeation and brain tissue binding.
Assessing the rate of drug delivery to the central nervous system (CNS) in vitro has been used for decades to predict whether CNS drug candidates are likely to attain their pharmacological targets, located within the brain parenchyma, at an effective dose. The predictive value of in vitro blood-brain barrier (BBB) models is therefore frequently assessed by comparing in vitro BBB permeability, usually quoted as the endothelial permeability coefficient (Pe) or apparent permeability (Papp), to their rate of BBB permeation measured in vivo, the latter being commonly assessed in rodents.
In collaboration with AstraZeneca (DMPK department, Södertälje, Sweden), the in vitro BBB permeability (Papp and Pe) of 27 marketed CNS drugs has been determined using a bovine in vitro BBB model and compared to their in vivo permeability (Pvivo), obtained by rat in-situ brain perfusion. The latter was taken from published data from Summerfield et al. (2007).
This comparison confirmed previous reports, showing a strong in vitro/in vivo correlation for hydrophilic compounds, characterized by low brain tissue binding and a weak correlation for lipophilic compounds, characterized by high brain tissue binding. This observation can be explained by the influence of brain tissue binding on the uptake of drugs into the CNS in vivo and the absence of possible brain tissue binding in vitro.
The use of glial cells (GC) in the in vitro BBB model to mimic brain tissue binding and the introduction of a new calculation method for in vitro BBB permeability (Pvitro) resulted in a strong correlation between the in vitro and in vivo rate of BBB permeation for the whole set of compounds. These findings might facilitate further in vitro to in vivo extrapolation for CNS drug candidates.
The aggregation of amyloid-β peptide (Aβ) has been linked to the formation of neuritic plaques, which are pathological hallmarks of Alzheimer's disease (AD). Various natural compounds have been ...suggested as therapeutics for AD. Among these compounds, resveratrol has aroused great interest due to its neuroprotective characteristics. Here, we provide evidence that grape skin and grape seed extracts increase the inhibition effect on Aβ aggregation. However, after intravenous injection, resveratrol is rapidly metabolized into both glucuronic acid and sulfate conjugations of the phenolic groups in the liver and intestinal epithelial cells (within less than 2 h), which are then eliminated. In the present study, we show that solid lipid nanoparticles (SLNs) functionalized with an antibody, the anti-transferrin receptor monoclonal antibody (OX26 mAb), can work as a possible carrier to transport the extract to target the brain. Experiments on human brain-like endothelial cells show that the cellular uptake of the OX26 SLNs is substantially more efficient than that of normal SLNs and SLNs functionalized with an unspecific antibody. As a consequence, the transcytosis ability of these different SLNs is higher when functionalized with OX-26.
Summary Background Angiogenesis is a target in the treatment of ovarian cancer. Nintedanib, an oral triple angiokinase inhibitor of VEGF receptor, platelet-derived growth factor receptor, and ...fibroblast growth factor receptor, has shown activity in phase 2 trials in this setting. We investigated the combination of nintedanib with standard carboplatin and paclitaxel chemotherapy in patients with newly diagnosed advanced ovarian cancer. Methods In this double-blind phase 3 trial, chemotherapy-naive patients (aged 18 years or older) with International Federation of Gynecology and Obstetrics (FIGO) IIB–IV ovarian cancer and upfront debulking surgery were stratified by postoperative resection status, FIGO stage, and planned carboplatin dose. Patients were randomly assigned (2:1) via an interactive voice or web-based response system to receive six cycles of carboplatin (AUC 5 mg/mL per min or 6 mg/mL per min) and paclitaxel (175 mg/m2 ) in addition to either 200 mg of nintedanib (nintedanib group) or placebo (placebo group) twice daily on days 2–21 of every 3-week cycle for up to 120 weeks. Patients, investigators, and independent radiological reviewers were masked to treatment allocation. The primary endpoint was investigator-assessed progression-free survival analysed in the intention-to-treat population. This trial is registered with ClinicalTrials.gov , number NCT01015118. Findings Between Dec 9, 2009, and July 27, 2011, 1503 patients were screened and 1366 randomly assigned by nine study groups in 22 countries: 911 to the nintedanib group and 455 to the placebo group. 486 (53%) of 911 patients in the nintedanib group experienced disease progression or death compared with 266 (58%) of 455 in the placebo group. Median progression-free survival was significantly longer in the nintedanib group than in the placebo group (17·2 months 95% CI 16·6–19·9 vs 16·6 months 13·9–19·1; hazard ratio 0·84 95% CI 0·72–0·98; p=0·024). The most common adverse events were gastrointestinal (diarrhoea: nintedanib group 191 21% of 902 grade 3 and three <1% grade 4 vs placebo group nine 2% of 450 grade 3 only) and haematological (neutropenia: nintedanib group 180 20% grade 3 and 200 (22%) grade 4 vs placebo group 90 20% grade 3 and 72 16% grade 4; thrombocytopenia: 105 12% and 55 6% vs 21 5% and eight 2%; anaemia: 108 12% and 13 1% vs 26 6% and five 1%). Serious adverse events were reported in 376 (42%) of 902 patients in the nintedanib group and 155 (34%) of 450 in the placebo group. 29 (3%) of 902 patients in the nintedanib group experienced serious adverse events associated with death compared with 16 (4%) of 450 in the placebo group, including 12 (1%) in the nintedanib group and six (1%) in the placebo group with a malignant neoplasm progression classified as an adverse event by the investigator. Drug-related adverse events leading to death occurred in three patients in the nintedanib group (one without diagnosis of cause; one due to non-drug-related sepsis associated with drug-related diarrhoea and renal failure; and one due to peritonitis) and in one patient in the placebo group (cause unknown). Interpretation Nintedanib in combination with carboplatin and paclitaxel is an active first-line treatment that significantly increases progression-free survival for women with advanced ovarian cancer, but is associated with more gastrointestinal adverse events. Future studies should focus on improving patient selection and optimisation of tolerability. Funding Boehringer Ingelheim.
Increase in blood-brain barrier (BBB) permeability is a crucial step in neuroinflammatory processes. We previously showed that N Methyl D Aspartate Receptor (NMDARs), expressed on cerebral ...endothelial cells forming the BBB, regulate immune cell infiltration across this barrier in the mouse. Here, we describe the mechanism responsible for the action of NMDARs on BBB permeabilization. We report that mouse CNS endothelial NMDARs display the regulatory GluN3A subunit. This composition confers to NMDARs' unconventional properties: these receptors do not induce Ca
influx but rather show nonionotropic properties. In inflammatory conditions, costimulation of human brain endothelial cells by NMDA agonists (NMDA or glycine) and the serine protease tissue plasminogen activator, previously shown to potentiate NMDAR activity, induces metabotropic signaling via the Rho/ROCK pathway. This pathway leads to an increase in permeability via phosphorylation of myosin light chain and subsequent shrinkage of human brain endothelial cells. Together, these data draw a link between NMDARs and the cytoskeleton in brain endothelial cells that regulates BBB permeability in inflammatory conditions.
The authors describe how NMDARs expressed on endothelial cells regulate blood-brain barrier function via myosin light chain phosphorylation and increase in permeability. They report that these non-neuronal NMDARs display distinct structural, functional, and pharmacological features than their neuronal counterparts.
Alzheimer’s disease (AD) is characterized by the abnormal accumulation of amyloid-β (Aβ) peptides in the brain. The pathological process has not yet been clarified, although dysfunctional transport ...of Aβ across the blood–brain barrier (BBB) appears to be integral to disease development. At present, no effective therapeutic treatment against AD exists, and the adoption of a ketogenic diet (KD) or ketone body (KB) supplements have been investigated as potential new therapeutic approaches. Despite experimental evidence supporting the hypothesis that KBs reduce the Aβ load in the AD brain, little information is available about the effect of KBs on BBB and their effect on Aβ transport. Therefore, we used a human in vitro BBB model, brain-like endothelial cells (BLECs), to investigate the effect of KBs on the BBB and on Aβ transport. Our results show that KBs do not modify BBB integrity and do not cause toxicity to BLECs. Furthermore, the presence of KBs in the culture media was combined with higher MCT1 and GLUT1 protein levels in BLECs. In addition, KBs significantly enhanced the protein levels of LRP1, P-gp, and PICALM, described to be involved in Aβ clearance. Finally, the combined use of KBs promotes Aβ efflux across the BBB. Inhibition experiments demonstrated the involvement of LRP1 and P-gp in the efflux. This work provides evidence that KBs promote Aβ clearance from the brain to blood in addition to exciting perspectives for studying the use of KBs in therapeutic approaches.
Characterizing interaction of newly synthetized molecules with efflux pumps remains essential to improve their efficacy and safety. Caco-2 cell line cultivated on inserts is widely used for measuring ...apparent permeability of drugs across biological barriers, and for estimating their interaction with efflux pumps such as P-gp, BCRP and MRPs. However, this method remains time consuming and expensive. In addition, detection method is required for measuring molecule passage across cell monolayer and false results can be generated if drugs concentrations used are too high as demonstrated with quinidine. For this reason, we developed a new protocol based on the use of Caco-2 cell directly seeded on 96- or 384-well plates and the use of fluorescent substrates for efflux pumps. We clearly observed that the new method reduces costs for molecule screening and leads to higher throughput compared to traditional use of Caco-2 cell model. This accelerated model could provide quick feedback regarding the molecule design during the early stage of drug discovery and therefore reduce the number of compounds to be further evaluated using the traditional Caco-2 insert method.
Neuroinflammation and brain lipid imbalances are observed in Alzheimer's disease (AD). Tumor necrosis factor-α (TNFα) and the liver X receptor (
) signaling pathways are involved in both processes. ...However, limited information is currently available regarding their relationships in human brain pericytes (HBP) of the neurovascular unit. In cultivated HBP, TNFα activates the
pathway and increases the expression of one of its target genes, the transporter ATP-binding cassette family A member 1 (
), while
is not expressed. Apolipoprotein E (
) synthesis and release are diminished. The cholesterol efflux is promoted, but is not inhibited, when
or
are blocked. Moreover, as for TNFα, direct
activation by the agonist (T0901317) increases
expression and the associated cholesterol efflux. However, this process is abolished when
/
are both inhibited. Neither the other ABC transporters nor the SR-BI are involved in this TNFα-mediated lipid efflux regulation. We also report that inflammation increases
expression and function. In conclusion, our data suggest that inflammation increases HBP protection against xenobiotics and triggers an
/
independent cholesterol release. Understanding the molecular mechanisms regulating this efflux at the level of the neurovascular unit remains fundamental to the characterization of links between neuroinflammation, cholesterol and HBP function in neurodegenerative disorders.
Summary Background Combining targeted treatments for renal cell carcinoma has been suggested as a possible method to improve treatment efficacy. We aimed to assess the potential synergistic or ...additive effect of the combination of bevacizumab, directed against the VEGF receptor, and temsirolimus, an mTOR inhibitor, in metastatic renal cell carcinoma. Methods TORAVA was an open-label, multicentre randomised phase 2 study undertaken in 24 centres in France. Patients aged 18 years or older who had untreated metastatic renal cell carcinoma were randomly assigned (2:1:1) to receive the combination of bevacizumab (10 mg/kg every 2 weeks) and temsirolimus (25 mg weekly; group A), or one of the standard treatments: sunitinib (50 mg/day for 4 weeks followed by 2 weeks off; group B), or the combination of interferon alfa (9 mIU three times per week) and bevacizumab (10 mg/kg every 2 weeks; group C). Randomisation was done centrally and independently from other study procedures with computer-generated permuted blocks of four and eight patients stratified by participating centre and Eastern Cooperative Oncology Group performance status. The primary endpoint was progression-free survival (PFS) at 48 weeks (four follow-up CT scans), which was expected to be above 50% in group A. Analysis was by intention to treat. The study is ongoing for long-term overall survival. This study is registered with ClinicalTrials.gov , number NCT00619268. Findings Between March 3, 2008 and May 6, 2009, 171 patients were randomly assigned: 88 to the experimental group (group A), 42 to group B, and 41 to group C. PFS at 48 weeks was 29·5% (26 of 88 patients, 95% CI 20·0–39·1) in group A, 35·7% (15 of 42, 21·2–50·2) in group B, and 61·0% (25 of 41, 46·0–75·9) in group C. Median PFS was 8·2 months (95% CI 7·0–9·6) in group A, 8·2 months (5·5–11·7) in group B, and 16·8 months (6·0–26·0) in group C. 45 (51%) of 88 patients in group A stopped treatment for reasons other than progression compared with five (12%) of 42 in group B and 15 (38%) of 40 in group C. Grade 3 or worse adverse events were reported in 68 (77%) of 88 patients in group A versus 25 (60%) of 42 in group B and 28 (70%) of 40 in group C. Serious adverse events were reported in 39 (44%) of 88, 13 (31%) of 42, and 18 (45%) of 40 patients in groups A, B, and C, respectively. Interpretation The toxicity of the temsirolimus and bevacizumab combination was much higher than anticipated and limited treatment continuation over time. Clinical activity was low compared with the benefit expected from sequential use of each targeted therapy. This combination cannot be recommended for first-line treatment in patients with metastatic renal cell carcinoma. Funding French Ministry of Health and Wyeth Pharmaceuticals.
Ganglioside GM1 (GM1) has been reported to functionally recover degenerated nervous system in vitro and in vivo, but the possibility to translate GM1's potential in clinical settings is counteracted ...by its low ability to overcome the blood-brain barrier (BBB) due to its amphiphilic nature. Interestingly, the soluble and hydrophilic GM1-oligosaccharide (OligoGM1) is able to punctually replace GM1 neurotrophic functions alone, both in vitro and in vivo. In order to take advantage of OligoGM1 properties, which overcome GM1's pharmacological limitations, here we characterize the OligoGM1 brain transport by using a human in vitro BBB model. OligoGM1 showed a 20-fold higher crossing rate than GM1 and time-concentration-dependent transport. Additionally, OligoGM1 crossed the barrier at 4 °C and in inverse transport experiments, allowing consideration of the passive paracellular route. This was confirmed by the exclusion of a direct interaction with the active ATP-binding cassette (ABC) transporters using the "pump out" system. Finally, after barrier crossing, OligoGM1 remained intact and able to induce Neuro2a cell neuritogenesis by activating the TrkA pathway. Importantly, these in vitro data demonstrated that OligoGM1, lacking the hydrophobic ceramide, can advantageously cross the BBB in comparison with GM1, while maintaining its neuroproperties. This study has improved the knowledge about OligoGM1's pharmacological potential, offering a tangible therapeutic strategy.
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