P-glycoprotein (ABCB1) and Oxidative Stress: Focus on Alzheimer's Disease

Structural insight into binding site access and ligand recognition by human ABCB1

ABCB1 is a broad-spectrum efflux pump central to cellular drug handling and multidrug resistance in humans. However, its mechanisms of poly-specific substrate recognition and transport remain poorly resolved. Here we present cryo-EM structures of lipid embedded human ABCB1 in its apo, substrate-bound, inhibitor-bound, and nucleotide-trapped states at 3.4-3.9 Å resolution without using stabilizing antibodies or mutations and each revealing a distinct conformation. The substrate binding site is located within one half of the molecule and, in the apo state, is obstructed by transmembrane helix (TM) 4. Substrate and inhibitor binding are distinguished by major differences in TM arrangement and ligand binding chemistry, with TM4 playing a central role in all conformational transitions. Our data offer fundamental new insights into the role structural asymmetry, secondary structure breaks, and lipid interactions play in ABCB1 function and have far-reaching implications for ABCB1 inhibitor design and predicting its substrate binding profiles.

QKL injection ameliorates Alzheimer's disease-like pathology by regulating expression of RAGE

The onset of Alzheimer's disease is related to neuron damage caused by massive deposition of Aβ in the brain. Recent studies suggest that excessive Aβ in the brain mainly comes from peripheral blood, and BBB is the key to regulate Aβ in and out of the brain. In this study, we explored the pathogenesis of AD from the perspective of Aβ transport through the BBB and the effect of QKL injection in AD mice. The results showed that QKL could improve the cognitive dysfunction of AD mice, decrease the level of Aβ and Aβ transporter-RAGE, which was supported by the results of network pharmacology, molecular docking and molecular dynamics simulation. In conclusion, RAGE is a potential target for QKL's therapeutic effect on AD.

Enhancing of cerebral Abeta clearance by modulation of ABC transporter expression: a review of experimental approaches

Clearance of amyloid-beta (Aβ) from the brain is impaired in both early-onset and late-onset Alzheimer's disease (AD). Mechanisms for clearing cerebral Aβ include proteolytic degradation, antibody-mediated clearance, blood brain barrier and blood cerebrospinal fluid barrier efflux, glymphatic drainage, and perivascular drainage. ATP-binding cassette (ABC) transporters are membrane efflux pumps driven by ATP hydrolysis. Their functions include maintenance of brain homeostasis by removing toxic peptides and compounds, and transport of bioactive molecules including cholesterol. Some ABC transporters contribute to lowering of cerebral Aβ. Mechanisms suggested for ABC transporter-mediated lowering of brain Aβ, in addition to exporting of Aβ across the blood brain and blood cerebrospinal fluid barriers, include apolipoprotein E lipidation, microglial activation, decreased amyloidogenic processing of amyloid precursor protein, and restricting the entrance of Aβ into the brain. The ABC transporter superfamily in humans includes 49 proteins, eight of which have been suggested to reduce cerebral Aβ levels. This review discusses experimental approaches for increasing the expression of these ABC transporters, clinical applications of these approaches, changes in the expression and/or activity of these transporters in AD and transgenic mouse models of AD, and findings in the few clinical trials which have examined the effects of these approaches in patients with AD or mild cognitive impairment. The possibility that therapeutic upregulation of ABC transporters which promote clearance of cerebral Aβ may slow the clinical progression of AD merits further consideration.

Irisin/PGC-1α/FNDC5 pathway in Parkinson's disease: truth under the throes

Parkinson's disease (PD) is considered one of the most common neurodegenerative brain diseases which involves the deposition of α-synuclein. Irisin hormone, a newly discovered adipokine, has a valuable role in diverse neurodegenerative diseases. Therefore, this review aims to elucidate the possible role of the irisin hormone in PD neuropathology. Irisin hormone has a neuroprotective effect against the development and progression of various neurodegenerative disorders by increasing the expression of brain-derived neurotrophic factor (BDNF). Irisin hormone has anti-inflammatory, anti-apoptotic, and anti-oxidative impacts, thereby reducing the expression of the pro-inflammatory cytokines and the progression of neuroinflammation. Irisin-induced PGC-1α could potentially prevent α-synuclein-induced dopaminergic injury, neuroinflammation, and neurotoxicity in PD. Inhibition of NF-κB by irisin improves PGC-1α and FNDC5 signaling pathway with subsequent attenuation of PD neuropathology. Therefore, the irisin/PGC-1α/FNDC5 pathway could prevent dopaminergic neuronal injury. In conclusion, the irisin hormone has a neuroprotective effect through its anti-inflammatory and antioxidant impacts with the amelioration of brain BDNF levels. Further preclinical and clinical studies are recommended in this regard.

Nicotinamide Mononucleotide (NMN) Works in Type 2 Diabetes through Unexpected Effects in Adipose Tissue, Not by Mitochondrial Biogenesis

Nicotinamide mononucleotide (NMN) has emerged as a promising therapeutic intervention for age-related disorders, including type 2 diabetes. In this study, we confirmed the previously observed effects of NMN treatment on glucose uptake and investigated its underlying mechanisms in various tissues and cell lines. Through the most comprehensive proteomic analysis to date, we discovered a series of novel organ-specific effects responsible for glucose uptake as measured by the IPGTT: adipose tissue growing (suggested by increased protein synthesis and degradation and mTOR proliferation signaling upregulation). Notably, we observed the upregulation of thermogenic UCP1, promoting enhanced glucose conversion to heat in intermuscular adipose tissue while showing a surprising repressive effect on mitochondrial biogenesis in muscle and the brain. Additionally, liver and muscle cells displayed a unique response, characterized by spliceosome downregulation and concurrent upregulation of chaperones, proteasomes, and ribosomes, leading to mildly impaired and energy-inefficient protein synthesis machinery. Furthermore, our findings revealed remarkable metabolic rewiring in the brain. This involved increased production of ketone bodies, downregulation of mitochondrial OXPHOS and TCA cycle components, as well as the induction of well-known fasting-associated effects. Collectively, our data elucidate the multifaceted nature of NMN action, highlighting its organ-specific effects and their role in improving glucose uptake. These findings deepen our understanding of NMN's therapeutic potential and pave the way for novel strategies in managing metabolic disorders.

Regulation of P-Glycoprotein during Oxidative Stress

P-glycoprotein (Pgp, ABCB1, MDR1) is an efflux transporter protein that removes molecules from the cells (outflow) into the extracellular space. Pgp plays an important role in pharmacokinetics, ensuring the absorption, distribution, and excretion of drugs and its substrates, as well as in the transport of endogenous molecules (steroid and thyroid hormones). It also contributes to tumor cell resistance to chemotherapy. In this review, we summarize the mechanisms of Pgp regulation during oxidative stress. The currently available data suggest that Pgp has a complex variety of regulatory mechanisms under oxidative stress, involving many transcription factors, the main ones being Nrf2 and Nf-kB. These factors often overlap, and some can be activated under certain conditions, such as the deposition of oxidation products, depending on the severity of oxidative stress. In most cases, the expression of Pgp increases due to increased transcription and translation, but under severe oxidative stress, it can also decrease due to the oxidation of amino acids in its molecule. At the same time, Pgp acts as a protector against oxidative stress, eliminating the causative factors and removing its by-products, as well as participating in signaling pathways.

Effects of DHA (omega-3 fatty acid) and estradiol on amyloid β-peptide regulation in the brain

In the early stages of sporadic Alzheimer's disease (SAD), there is a strong correlation between memory impairment and cortical levels of soluble amyloid-β peptide oligomers (Aβ). It has become clear that Aβ disrupt glutamatergic synaptic function, which can in turn lead to the characteristic cognitive deficits of SAD, but the actual pathways are still not well understood. This opinion article describes the pathogenic mechanisms underlying cerebral amyloidosis. These mechanisms are dependent on the amyloid precursor protein and concern the synthesis of Aβ peptides with competition between the non-amyloidogenic pathway and the amyloidogenic pathway (i.e. a competition between the ADAM10 and BACE1 enzymes), on the one hand, and the various processes of Aβ residue clearance, on the other hand. This clearance mobilizes both endopeptidases (NEP, and IDE) and removal transporters across the blood-brain barrier (LRP1, ABCB1, and RAGE). Lipidated ApoE also plays a major role in all processes. The disturbance of these pathways induces an accumulation of Aβ. The description of the mechanisms reveals two key molecules in particular: (i) free estradiol, which has genomic and non-genomic action, and (ii) free DHA as a preferential ligand of PPARα-RXRα and PPARɣ-RXRα heterodimers. DHA and free estradiol are also self-regulating, and act in synergy. When a certain level of chronic DHA and free estradiol deficiency is reached, a permanent imbalance is established in the central nervous system. The consequences of these deficits are revealed in particular by the presence of Aβ peptide deposits, as well as other markers of the etiology of SAD.

Extranodal lymphoma: pathogenesis, diagnosis and treatment

Approximately 30% of lymphomas occur outside the lymph nodes, spleen, or bone marrow, and the incidence of extranodal lymphoma has been rising in the past decade. While traditional chemotherapy and radiation therapy can improve survival outcomes for certain patients, the prognosis for extranodal lymphoma patients remains unsatisfactory. Extranodal lymphomas in different anatomical sites often have distinct cellular origins, pathogenic mechanisms, and clinical manifestations, significantly influencing their diagnosis and treatment. Therefore, it is necessary to provide a comprehensive summary of the pathogenesis, diagnosis, and treatment progress of extranodal lymphoma overall and specifically for different anatomical sites. This review summarizes the current progress in the common key signaling pathways in the development of extranodal lymphomas and intervention therapy. Furthermore, it provides insights into the pathogenesis, diagnosis, and treatment strategies of common extranodal lymphomas, including gastric mucosa-associated lymphoid tissue (MALT) lymphoma, mycosis fungoides (MF), natural killer/T-cell lymphoma (nasal type, NKTCL-NT), and primary central nervous system lymphoma (PCNSL). Additionally, as PCNSL is one of the extranodal lymphomas with the worst prognosis, this review specifically summarizes prognostic indicators and discusses the challenges and opportunities related to its clinical applications. The aim of this review is to assist clinical physicians and researchers in understanding the current status of extranodal lymphomas, enabling them to make informed clinical decisions that contribute to improving patient prognosis.

Vascular contributions to Alzheimer's disease

Alzheimer's disease (AD) is the most common cause of dementia and is characterized by progressive neurodegeneration and cognitive decline. Understanding the pathophysiology underlying AD is paramount for the management of individuals at risk of and suffering from AD. The vascular hypothesis stipulates a relationship between cardiovascular disease and AD-related changes although the nature of this relationship remains unknown. In this review, we discuss several potential pathological pathways of vascular involvement in AD that have been described including dysregulation of neurovascular coupling, disruption of the blood brain barrier, and reduced clearance of metabolite waste such as beta-amyloid, a toxic peptide considered the hallmark of AD. We will also discuss the two-hit hypothesis which proposes a 2-step positive feedback loop in which microvascular insults precede the accumulation of Aß and are thought to be at the origin of the disease development. At neuroimaging, signs of vascular dysfunction such as chronic cerebral hypoperfusion have been demonstrated, appearing early in AD, even before cognitive decline and alteration of traditional biomarkers. Cerebral small vessel disease such as cerebral amyloid angiopathy, characterized by the aggregation of Aß in the vessel wall, is highly prevalent in vascular dementia and AD patients. Current data is unclear whether cardiovascular disease causes, precipitates, amplifies, precedes, or simply coincides with AD. Targeted imaging tools to quantitatively evaluate the intracranial vasculature and longitudinal studies in individuals at risk for or in the early stages of the AD continuum could be critical in disentangling this complex relationship between vascular disease and AD.

The relationship among amyloid-β deposition, sphingomyelin level, and the expression and function of P-glycoprotein in Alzheimer's disease pathological process

In Alzheimer's disease, the transporter P-glycoprotein is responsible for the clearance of amyloid-β in the brain. Amyloid-β correlates with the sphingomyelin metabolism, and sphingomyelin participates in the regulation of P-glycoprotein. The amyloid cascade hypothesis describes amyloid-β as the central cause of Alzheimer's disease neuropathology. Better understanding of the change of P-glycoprotein and sphingomyelin along with amyloid-β and their potential association in the pathological process of Alzheimer's disease is critical. Herein, we found that the expression of P-glycoprotein in APP/PS1 mice tended to increase with age and was significantly higher at 9 and 12 months of age than that in wild-type mice at comparable age. The functionality of P-glycoprotein of APP/PS1 mice did not change with age but was significantly lower than that of wild-type mice at 12 months of age. Decreased sphingomyelin levels, increased ceramide levels, and the increased expression and activity of neutral sphingomyelinase 1 were observed in APP/PS1 mice at 9 and 12 months of age compared with the levels in wild-type mice. Similar results were observed in the Alzheimer's disease mouse model induced by intracerebroventricular injection of amyloid-β1-42 and human cerebral microvascular endothelial cells treated with amyloid-β1-42. In human cerebral microvascular endothelial cells, neutral sphingomyelinase 1 inhibitor interfered with the changes of sphingomyelin metabolism and P-glycoprotein expression and functionality caused by amyloid-β1-42 treatment. Neutral sphingomyelinase 1 regulated the expression and functionality of P-glycoprotein and the levels of sphingomyelin and ceramide. Together, these findings indicate that neutral sphingomyelinase 1 regulates the expression and function of P-glycoprotein via the sphingomyelin/ceramide pathway. These studies may serve as new pursuits for the development of anti-Alzheimer's disease drugs.

Selective Fluorescent Probes for High-Throughput Functional Diagnostics of the Human Multidrug Transporter P-Glycoprotein (ABCB1)

The multidrug transporter ABCB1 (MDR1, Pgp) plays an important role in the absorption, distribution, metabolism, and elimination of a wide range of pharmaceutical compounds. Functional investigation of the ABCB1 expression is also essential in many diseases, including drug-resistant cancer, inflammatory conditions, or Alzheimer disease. In this study, we examined the potential interaction of the ABCB1 multidrug transporter with a group of commercially available viability dyes that are generally considered not to penetrate into intact cells. Here, we demonstrate that the slow cellular accumulation of TO-PRO™-1 (TP1) or TO-PRO™-3 (TP3) was strongly inhibited by ABCB1-dependent dye extrusion. TP1/3 dye accumulation was not affected by the presence of ABCC1 or ABCG2, while this uptake was increased to the level in the ABCB1-negative cells by a specific P-glycoprotein inhibitor, Tariquidar. We suggest that TP compounds can be used as highly sensitive, selective, non-toxic, and stable dyes to examine the functional expression and properties of the ABCB1 multidrug transporter, especially in microplate-based high-throughput flow cytometry assays. In addition, we demonstrate the applicability of the TP dyes to efficiently select and separate even a very low number of Pgp-expressing intact cells.

Calpain Inhibitor Calpeptin Improves Alzheimer's Disease-Like Cognitive Impairments and Pathologies in a Diabetes Mellitus Rat Model

Diabetes mellitus (DM) has been considered an accelerator of Alzheimer's disease (AD), but the cellular and molecular mechanisms underlying this effect are not fully understood. Here, we attempted to determine the role and regulatory mechanism of calpain in the AD-like cognitive decline and pathological changes in rats caused by DM. In the initial stages, our results verified that DM model rats showed cognitive impairment, as well as a loss of neurons, decreased pericyte marker (PDGFR-β and α-SMA), and calpain-2 expression and amyloid-β (Aβ) deposition in the hippocampal tissues. In high glucose-induced primary pericytes, the cell apoptotic rate was increased, and cell proliferation was inhibited in a time-dependent manner. The protein level of calpain-2 was also upregulated by HG induction, but the level of calpain-1 did not change with HG treatment, which was also observed in DM model rats. Subsequently, some DM model rats were administered calpeptin, an inhibitor of calpain. Our data revealed that calpeptin treatment significantly suppressed calpain-1 and calpain-2 expression in the hippocampal tissues and effectively improved the cognitive impairments of DM model rats. Neuronal loss, Aβ accumulation, pericyte loss, inflammation, and oxidative stress injury in the hippocampal tissues of DM model rats were also partly rescued by calpeptin administration. Our work demonstrated that the calpain inhibitor calpeptin could alleviate DM-induced AD-like cognitive impairments and pathological changes in rats, and this effect may be associated with pericytes. Calpeptin may become a promising drug to treat the AD-like complications of DM.

Screening Biomarkers for Systemic Lupus Erythematosus Based on Machine Learning and Exploring Their Expression Correlations With the Ratios of Various Immune Cells

Background

Systemic lupus erythematosus (SLE) is an autoimmune illness caused by a malfunctioning immunomodulatory system. China has the second highest prevalence of SLE in the world, from 0.03% to 0.07%. SLE is diagnosed using a combination of immunological markers, clinical symptoms, and even invasive biopsy. As a result, genetic diagnostic biomarkers for SLE diagnosis are desperately needed.

Method

From the Gene Expression Omnibus (GEO) database, we downloaded three array data sets of SLE patients' and healthy people's peripheral blood mononuclear cells (PBMC) (GSE65391, GSE121239 and GSE61635) as the discovery metadata (n_SLE = 1315, n_normal = 122), and pooled four data sets (GSE4588, GSE50772, GSE99967, and GSE24706) as the validate data set (n_SLE = 146, n_normal = 76). We screened the differentially expressed genes (DEGs) between the SLE and control samples, and employed the least absolute shrinkage and selection operator (LASSO) regression, and support vector machine recursive feature elimination (SVM-RFE) analyze to discover possible diagnostic biomarkers. The candidate markers' diagnostic efficacy was assessed using the receiver operating characteristic (ROC) curve. The reverse transcription quantitative polymerase chain reaction (RT-qPCR) was utilized to confirm the expression of the putative biomarkers using our own Chinese cohort (n_SLE = 13, n_normal = 10). Finally, the proportion of 22 immune cells in SLE patients was determined using the CIBERSORT algorithm, and the correlations between the biomarkers' expression and immune cell ratios were also investigated.

Results

We obtained a total of 284 DEGs and uncovered that they were largely involved in several immune relevant pathways, such as type І interferon signaling pathway, defense response to virus, and inflammatory response. Following that, six candidate diagnostic biomarkers for SLE were selected, namely ABCB1, EIF2AK2, HERC6, ID3, IFI27, and PLSCR1, whose expression levels were validated by the discovery and validation cohort data sets. As a signature, the area under curve (AUC) values of these six genes reached to 0.96 and 0.913, respectively, in the discovery and validation data sets. After that, we checked to see if the expression of ABCB1, IFI27, and PLSCR1 in our own Chinese cohort matched that of the discovery and validation sets. Subsequently, we revealed the potentially disturbed immune cell types in SLE patients using the CIBERSORT analysis, and uncovered the most relevant immune cells with the expression of ABCB1, IFI27, and PLSCR1.

Conclusion

Our study identified ABCB1, IFI27, and PLSCR1 as potential diagnostic genes for Chinese SLE patients, and uncovered their most relevant immune cells. The findings in this paper provide possible biomarkers for diagnosing Chinese SLE patients.

A Set of Dysregulated Target Genes to Reduce Neuroinflammation at Molecular Level

Increasing evidence links chronic neurodegenerative diseases with neuroinflammation; it is known that neuroprotective agents are capable of modulating the inflammatory processes, that occur with the onset of neurodegeneration pathologies. Here, with the intention of providing a means for active compounds’ screening, a dysregulation of neuronal inflammatory marker genes was induced and subjected to neuroprotective active principles, with the aim of selecting a set of inflammatory marker genes linked to neurodegenerative diseases. Considering the important role of microglia in neurodegeneration, a murine co-culture of hippocampal cells and inflamed microglia cells was set up. The evaluation of differentially expressed genes and subsequent in silico analysis showed the main dysregulated genes in both cells and the principal inflammatory processes involved in the model. Among the identified genes, a well-defined set was chosen, selecting those in which a role in human neurodegenerative progression in vivo was already defined in literature, matched with the rate of prediction derived from the Principal Component Analysis (PCA) of in vitro treatment-affected genes variation. The obtained panel of dysregulated target genes, including Cxcl9 (Chemokine (C-X-C motif) ligand 9), C4b (Complement Component 4B), Stc1 (Stanniocalcin 1), Abcb1a (ATP Binding Cassette Subfamily B Member 1), Hp (Haptoglobin) and Adm (Adrenomedullin), can be considered an in vitro tool to select old and new active compounds directed to neuroinflammation.

3,6'-disinapoyl sucrose attenuates Aβ1-42 - induced neurotoxicity in Caenorhabditis elegans by enhancing antioxidation and regulating autophagy

The aggregation of β‐amyloid (Aβ) has the neurotoxicity, which is thought to play critical role in the pathogenesis of Alzheimer's disease (AD). Inhibiting Aβ deposition and neurotoxicity has been considered as an important strategy for AD treatment. 3,6'‐Disinapoyl sucrose (DISS), one of the oligosaccharide esters derived from traditional Chinese medicine Polygalae Radix, possesses antioxidative activity, neuroprotective effect and anti‐depressive activity. This study was to explore whether DISS could attenuate the pathological changes of Aβ_1‐42 transgenic Caenorhabditis elegans (C. elegans). The results showed that DISS (5 and 50 μM) treatment significantly prolonged the life span, increased the number of egg‐laying, reduced paralysis rate, decreased the levels of lipofuscin and ROS and attenuated Aβ deposition in Aβ_1‐42 transgenic C. elegans. Gene analysis showed that DISS could up‐regulate the mRNA expression of sod‐3, gst‐4, daf‐16, bec‐1 and lgg‐1, while down‐regulate the mRNA expression of daf‐2 and daf‐15 in Aβ_1‐42 transgenic C. elegans. These results suggested that DISS has the protective effect against Aβ_1‐42‐induced pathological damages and prolongs the life span of C. elegans, which may be related to the reduction of Aβ deposition and neurotoxicity by regulating expression of genes related to antioxidation and autophagy.

Targeting Systemic Innate Immune Cells as a Therapeutic Avenue for Alzheimer Disease

Alzheimer disease (AD) is the first progressive neurodegenerative disease worldwide, and the disease is characterized by an accumulation of amyloid in the brain and neurovasculature that triggers cognitive decline and neuroinflammation. The innate immune system has a preponderant role in AD. The last decade, scientists focused their efforts on therapies aiming to modulate innate immunity. The latter is of great interest, since they participate to the inflammation and phagocytose the amyloid in the brain and blood vessels. We and others have developed pharmacological approaches to stimulate these cells using various ligands. These include toll-like receptor 4, macrophage colony stimulating factor, and more recently nucleotide-binding oligomerization domain-containing 2 receptors. This review will discuss the great potential to take advantage of the innate immune system to fight naturally against amyloid β accumulation and prevent its detrimental consequence on brain functions and its vascular system. SIGNIFICANCE STATEMENT: The focus on amyloid β removal from the perivascular space rather than targeting CNS plaque formation and clearance represents a new direction with a great potential. Small molecules able to act at the level of peripheral immunity would constitute a novel approach for tackling aberrant central nervous system biology, one of which we believe would have the potential of generating a lot of interest.

First clinical assessment of [18F]MC225, a novel fluorine-18 labelled PET tracer for measuring functional P-glycoprotein at the blood-brain barrier

OBJECTIVE

5-(1-(2-[18F]fluoroethoxy))-[3-(6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl)-propyl]-5,6,7,8-tetrahydronaphthalen ([18F]MC225) is a selective substrate for P-glycoprotein (P-gp), possessing suitable properties for measuring overexpression of P-gp in the brain. This is the first-in-human study to examine safety, radiation dosimetry and P-gp function at the blood-brain barrier (BBB) of [18F]MC225 in healthy subjects.

METHODS

[18F]MC225 biodistribution and dosimetry were determined in 3 healthy male subjects, using serial 2 h and intermittent 4 and 6 h whole-body PET scans acquired after [18F]MC225 injection. Dynamic [18F]MC225 brain PET (90 min) was obtained in 5 healthy male subjects. Arterial blood was sampled at various time intervals during scanning and the fraction of unchanged [18F]MC225 in plasma was determined. T1-weighted MRI was performed for anatomical coregistration. Total distribution volume (VT) was estimated using 1- and 2-tissue-compartment models (1-TCM and 2-TCM, respectively). VT was also estimated using the Logan graphical method (Logan plot) (t* = 20 min). Surrogate parameters without blood sampling (area-under the curve [AUC] of regional time-activity curves [TACs] and negative slope of calculated TACs) were compared with the VT values.

RESULTS

No serious adverse events occurred throughout the study period. Although biodistribution implied hepatobiliary excretion, secretion of radioactivity from liver to small intestine through the gallbladder was very slow. Total renal excreted radioactivity recovered during 6 h after injection was < 2%ID. Absorbed dose was the highest in the pancreas (mean ± SD, 203 ± 45 μGy/MBq) followed by the liver (83 ± 11 μGy/MBq). Mean effective dose with and without urination was 17 ± 1 μSv/MBq. [18F]MC225 readily entered the brain, distributing homogeneously in grey matter regions. 2-TCM provided lower Akaike information criterion scores than did 1-TCM. VT estimated by Logan plot was well correlated with that of 2-TCM (r2 > 0.9). AUCs of TACs were positively correlated with VT (2-TCM) values (r2: AUC0-60 min = 0.61, AUC0-30 min = 0.62, AUC30-60 min = 0.59, p < 0.0001). Negative slope of SUV TACs was negatively correlated with VT (2-TCM) values (r2 = 0.53, p < 0.0001).

CONCLUSIONS

This initial evaluation indicated that [18F]MC225 is a suitable and safe PET tracer for measuring P-gp function at the BBB.

The Blood-Brain Barrier, Oxidative Stress, and Insulin Resistance

The blood–brain barrier (BBB) is a network of specialized endothelial cells that regulates substrate entry into the central nervous system (CNS). Acting as the interface between the periphery and the CNS, the BBB must be equipped to defend against oxidative stress and other free radicals generated in the periphery to protect the CNS. There are unique features of brain endothelial cells that increase the susceptibility of these cells to oxidative stress. Insulin signaling can be impacted by varying levels of oxidative stress, with low levels of oxidative stress being necessary for signaling and higher levels being detrimental. Insulin must cross the BBB in order to access the CNS, levels of which are important in peripheral metabolism as well as cognition. Any alterations in BBB transport due to oxidative stress at the BBB could have downstream disease implications. In this review, we cover the interactions of oxidative stress at the BBB, how insulin signaling is related to oxidative stress, and the impact of the BBB in two diseases greatly affected by oxidative stress and insulin resistance: diabetes mellitus and Alzheimer’s disease.

Uptake of Aβ by OATPs might be a new pathophysiological mechanism of Alzheimer disease

BACKGROUND

The accumulation of neurotoxic amyloid-beta (Aβ) in the brain is a characteristic of Alzheimer's disease (AD), at the same time, it is possible alterations of liver function could affect brain Aβ levels through changes in blood Aβ concentration. Over the last decade, a number of reports have shown that P-glycoprotein (encoded by ABC1B1) actively mediates the efflux transport of Aβ peptides. However, the mechanism by which Aβ peptides enter the cells is not clear. In the preliminary study, we found that the protein expression of organic anion transporting Polypeptide 1a4 (OATP1B1) in the liver tissue of mice with AD was significantly higher than that in the normal mice. In contrast, the protein expression of Oatp1a4 in the brain significantly decreased in mice with AD. OATP1B1, an important drug transporter might be related to the pathophysiology of AD.

RESULTS

In this study, we established an OATP1B1-GFP-HEK293T cell model to confirm the OATP1B1 mediated transport of Aβ_1-42. Compared to the control group of GFP-HEK293Tcells, the uptake of Aβ_1-42 protein in the OATP1B1-GFP-HEK293T group increased significantly with the increase in concentration of Aβ_1-42, and also increased significantly with an increase in the duration of incubation. Similar results were observed in the flow cytometry experiment, and the uptake of Aβ_1-42in HEK293T-OATP1B1 cells was almost twice that in the control group. These results indicate that OATPs may act as an important "carrier" for the transport of Aβ1-42 from the blood to the tissues, including liver and brain.

CONCLUSIONS

This is a novel and interesting finding and OATP1B1 can be investigated as a new treatment target for AD.

Oxidative Stress and the Neurovascular Unit

The neurovascular unit (NVU) is a relatively recent concept that clearly describes the relationship between brain cells and their blood vessels. The components of the NVU, comprising different types of cells, are so interrelated and associated with each other that they are considered as a single functioning unit. For this reason, even slight disturbances in the NVU could severely affect brain homeostasis and health. In this review, we aim to describe the current state of knowledge concerning the role of oxidative stress on the neurovascular unit and the role of a single cell type in the NVU crosstalk.

Genetic Variants and Oxidative Stress in Alzheimer's Disease

In an aging society, the number of people suffering from Alzheimer's Disease (AD) is still growing. Currently, intensive research is being carried out on the pathogenesis of AD. The results of these studies indicated that oxidative stress plays an important role in the onset and development of this disease. Moreover, in AD oxidative stress is generated by both genetic and biochemical factors as well as the functioning of the systems responsible for their formation and removal. The genetic factors associated with the regulation of the redox system include TOMM40, APOE, LPR, MAPT, APP, PSEN1 and PSEN2 genes. The most important biochemical parameters related to the formation of oxidative species in AD are p53, Homocysteine (Hcy) and a number of others. The formation of Reactive Oxygen Species (ROS) is also related to the efficiency of the DNA repair system, the effectiveness of the apoptosis, autophagy and mitophagy processes as well as the antioxidant potential. However, these factors are responsible for the development of many disorders, often with similar clinical symptoms, especially in the early stages of the disease. The discovery of markers of the early diagnosis of AD may contribute to the introduction of pharmacotherapy and slow down the progression of this disease.

Clinically-Relevant ABC Transporter for Anti-Cancer Drug Resistance

Multiple drug resistance (MDR), referring to the resistance of cancer cells to a broad spectrum of structurally and mechanistically unrelated drugs across membranes, severely impairs the response to chemotherapy and leads to chemotherapy failure. Overexpression of ATP binding cassette (ABC) transporters is a major contributing factor resulting in MDR, which can recognize and mediate the efflux of diverse drugs from cancer cells, thereby decreasing intracellular drug concentration. Therefore, modulators of ABC transporter could be used in combination with standard chemotherapeutic anticancer drugs to augment the therapeutic efficacy. This review summarizes the recent advances of important cancer-related ABC transporters, focusing on their physiological functions, structures, and the development of new compounds as ABC transporter inhibitors.

New Evidence for P-gp-Mediated Export of Amyloid-β PEPTIDES in Molecular, Blood-Brain Barrier and Neuronal Models

Defective clearance mechanisms lead to the accumulation of amyloid-beta (Aβ) peptides in the Alzheimer’s brain. Though predominantly generated in neurons, little is known about how these hydrophobic, aggregation-prone, and tightly membrane-associated peptides exit into the extracellular space where they deposit and propagate neurotoxicity. The ability for P-glycoprotein (P-gp), an ATP-binding cassette (ABC) transporter, to export Aβ across the blood-brain barrier (BBB) has previously been reported. However, controversies surrounding the P-gp–Aβ interaction persist. Here, molecular data affirm that both Aβ₄₀ and Aβ₄₂ peptide isoforms directly interact with and are substrates of P-gp. This was reinforced ex vivo by the inhibition of Aβ₄₂ transport in brain capillaries from P-gp-knockout mice. Moreover, we explored whether P-gp could exert the same role in neurons. Comparison between non-neuronal CHO-APP and human neuroblastoma SK-N-SH cells revealed that P-gp is expressed and active in both cell types. Inhibiting P-gp activity using verapamil and nicardipine impaired Aβ₄₀ and Aβ₄₂ secretion from both cell types, as determined by ELISA. Collectively, these findings implicate P-gp in Aβ export from neurons, as well as across the BBB endothelium, and suggest that restoring or enhancing P-gp function could be a viable therapeutic approach for removing excess Aβ out of the brain in Alzheimer’s disease.

Structure and Function of Hepatobiliary ATP Binding Cassette Transporters

The liver is beyond any doubt the most important metabolic organ of the human body. This function requires an intensive crosstalk within liver cellular structures, but also with other organs. Membrane transport proteins are therefore of upmost importance as they represent the sensors and mediators that shuttle signals from outside to the inside of liver cells and/or vice versa. In this review, we summarize the known literature of liver transport proteins with a clear emphasis on functional and structural information on ATP binding cassette (ABC) transporters, which are expressed in the human liver. These primary active membrane transporters form one of the largest families of membrane proteins. In the liver, they play an essential role in for example bile formation or xenobiotic export. Our review provides a state of the art and comprehensive summary of the current knowledge of hepatobiliary ABC transporters. Clearly, our knowledge has improved with a breath-taking speed over the last few years and will expand further. Thus, this review will provide the status quo and will lay the foundation for new and exciting avenues in liver membrane transporter research.

MDR-1 function protects oocyte mitochondria against the transgenerational effects of nitrogen mustard exposure

Oocytes are vulnerable to alkylating agents like nitrogen mustard (NM), which can cause mitochondrial dysfunction associated with increased oxidative stress. Because mitochondria are maternally inherited, NM exposure affects oocyte mitochondrial physiology and compromises future progeny. Multidrug resistance transporters (MDRs) are transmembrane proteins that efflux such cytotoxic substances; MDR-1 is expressed in oocyte plasma and mitochondrial membranes and protects against oxidative stress. Our objective was to investigate how loss of MDR-1 can modulate oocyte response to NM transgenerationally. Wild Type (WT) and Mdr1a mutant female mice were injected intraperitoneally with sterile saline (control) or 0.1 mg/kg NM. 48 h post-injection, females were either sacrificed for F0 studies or mated with control males to yield F1 pups. After weaning, F1 females were sacrificed or mated to yield F2 pups. Germinal vesicle oocytes were assessed for mitochondrial membrane potential and reactive oxygen species (ROS) levels. NM exposed oocytes of both genotypes exhibited significantly higher ROS than controls in F0 and F1. NM F2 oocytes of neither genotype exhibited significantly higher ROS, though variation in Mdr1a mutants led to an upward trend. NM oocytes of both genotypes exhibited significantly disrupted mitochondrial membrane potential in F0. WT regained normalcy by F1 whereas Mdr1a mutants were unable to by F2. Our data suggest that Mdr1a mutants exhibit transgenerational mitochondrial dysfunction following toxic challenge that persists, implying that MDR-1 protects against toxicant-induced mitochondrial stress. Women without functional MDR-1 exposed to environmental toxicants could therefore be at risk for passing on compromised mitochondria to future offspring.

The Role of Neurovascular System in Neurodegenerative Diseases

The neurovascular system (NVS), which consisted of neurons, glia, and vascular cells, is a functional and structural unit of the brain. The NVS regulates blood-brain barrier (BBB) permeability and cerebral blood flow (CBF), thereby maintaining the brain's microenvironment for normal functioning, neuronal survival, and information processing. Recent studies have highlighted the role of vascular dysfunction in several neurodegenerative diseases. This is not unexpected since both nervous and vascular systems are functionally interdependent and show close anatomical apposition, as well as similar molecular pathways. However, despite extensive research, the precise mechanism by which neurovascular dysfunction contributes to neurodegeneration remains incomplete. Therefore, understanding the mechanisms of neurovascular dysfunction in disease conditions may allow us to develop potent and effective therapies for prevention and treatment of neurodegenerative diseases. This review article summarizes the current research in the context of neurovascular signaling associated with neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and Huntington's disease (HD). We also discuss the potential implication of neurovascular factor as a novel therapeutic target and prognostic marker in patients with neurodegenerative conditions. Graphical Abstract.

Emerging promise of sulforaphane-mediated Nrf2 signaling cascade against neurological disorders

Neurological disorders represent a great challenge and are the leading cause of death and disability globally. Although numerous complicated mechanisms are involved in the progressions of chronic and acute neurodegenerative disorders, most of the diseases share mutual pathogenic features such as oxidative stress, mitochondrial dysfunction, neuroinflammation, protein misfolding, excitotoxicity, and neuronal damage, all of these are the common targets of nuclear factor erythroid 2 related factor 2 (Nrf2) signaling cascade. No cure has yet been discovered to tackle these disorders, so, intervention approaches targeting phytochemicals have been recommended as an alternative form of treatment. Sulforaphane is a sulfur-rich dietary phytochemical which has several activities such as antioxidant, anti-inflammatory, and anti-tumor via multiple targets and various mechanisms. Given its numerous actions, sulforaphane has drawn considerable attention for neurological disorders in recent years. Nrf2 is one of the most crucial targets of sulforaphane which has potential in regulating the series of cytoprotective enzyme expressions that have neuroprotective, antioxidative, and detoxification actions. Neurological disorders are auspicious candidates for Nrf2-targeted treatment strategy. Sulforaphane protects various neurological disorders by regulating the Nrf2 pathway. In this article, we recapitulate current studies of sulforaphane-mediated Nrf2 activation in the treatment of various neurological disorders.

Alteration in the Function and Expression of SLC and ABC Transporters in the Neurovascular Unit in Alzheimer's Disease and the Clinical Significance

The neurovascular unit (NVU) plays an important role in maintaining the function of the central nervous system (CNS). Emerging evidence has indicated that the NVU changes function and molecules at the early stage of Alzheimer’s disease (AD), which initiates multiple pathways of neurodegeneration. Cell types in the NVU have become attractive targets in the interventional treatment of AD. The NVU transportation system contains a variety of proteins involved in compound transport and neurotransmission. Brain transporters can be classified as members of the solute carrier (SLC) and ATP-binding cassette (ABC) families in the NVU. Moreover, the transporters can regulate both endogenous toxins, including amyloid-beta (Aβ) and xenobiotic homeostasis, in the brains of AD patients. Genome-wide association studies (GWAS) have identified some transporter gene variants as susceptibility loci for late-onset AD. Therefore, the present study summarizes changes in blood-brain barrier (BBB) permeability in AD, identifies the location of SLC and ABC transporters in the brain and focuses on major SLC and ABC transporters that contribute to AD pathology.

Alzheimer's Disease: The Link Between Amyloid-β and Neurovascular Dysfunction

While prevailing evidence supports that the amyloid cascade hypothesis is a key component of Alzheimer's disease (AD) pathology, many recent studies indicate that the vascular system is also a major contributor to disease progression. Vascular dysfunction and reduced cerebral blood flow (CBF) occur prior to the accumulation and aggregation of amyloid-β (Aβ) plaques and hyperphosphorylated tau tangles. Although research has predominantly focused on the cellular processes involved with Aβ-mediated neurodegeneration, effects of Aβ on CBF and neurovascular coupling are becoming more evident. This review will describe AD vascular disturbances as they relate to Aβ, including chronic cerebral hypoperfusion, hypertension, altered neurovascular coupling, and deterioration of the blood-brain barrier. In addition, we will describe recent findings about the relationship between these vascular defects and Aβ accumulation with emphasis on in vivo studies utilizing rodent AD models.

ABC Transporters in Neurological Disorders: An Important Gateway for Botanical Compounds Mediated Neuro-Therapeutics

Neurodegeneration is a distinguishing feature of many age related disorders and other vector borne neuroinflammatory diseases. There are a number of factors that can modulate the pathology of these disorders. ATP-binding cassette (ABC) transporters are primarily involved in the maintenance of normal brain homeostasis by eliminating toxic peptides and compounds from the brain. Also, ABC transporters protect the brain from the unwanted effects of endogenous and exogenous toxins that can enter the brain parenchyma. Therefore, these transporters have the ability to determine the pathological outcomes of several neurological disorders. For instance, ABC transporters like P-glycoprotein (ABCB1), and BCRP (ABCG2) have been reported to facilitate the clearance of peptides such as amyloid-β (Aβ) that accumulate in the brain during Alzheimer's disease (AD) progression. Other members such as ABCA1, ABCA2, ABCC8, ABCC9, ABCG1 and ABCG4 also have been reported to be involved in the progression of various brain disorders such as HIV-associated dementia, Multiple sclerosis (MS), Ischemic stroke, Japanese encephalitis (JE) and Epilepsy. However, these defective transporters can be targeted by numerous botanical compounds such as Verapamil, Berberine and Fascalpsyn as a therapeutic target to treat these neurological outcomes. These compounds are already reported to modulate ABC transporter activity in the CNS. Nonetheless, the exact mechanisms involving the ABC transporters role in normal brain functioning, their role in neuronal dysfunction and how these botanical compounds ensure and facilitate their therapeutic action in association with defective transporters still remain elusive. This review therefore, summarizes the role of ABC transporters in neurological disorders, with a special emphasis on its role in AD brains. The prospect of using botanical/natural compounds as modulators of ABC transporters in neurological disorders is discussed in the latter half of the article.

Dysfunctional MDR-1 disrupts mitochondrial homeostasis in the oocyte and ovary

Multidrug resistance transporters (MDRs) are best known for their pathological role in neoplastic evasion of chemotherapeutics and antibiotics. Here we show that MDR-1 is present in the oocyte mitochondrial membrane, and it protects the female gamete from oxidative stress. Female mdr1a mutant mice have no significant difference in ovarian follicular counts and stages, nor in reproductively functioning hormone levels, yet these mice are significantly more vulnerable to gonadotoxic chemotherapy, have chronically elevated reactive oxygen species in immature germinal vesicle oocytes, exhibit a significant over-accumulation of metabolites involved in the tricarboxylic acid cycle (TCA), and have abnormal mitochondrial membrane potential. The mdr1a mutant ovaries have a dramatically different transcriptomic profile with upregulation of genes involved in metabolism. Our findings indicate that functionality of MDR-1 reveals a critical intersection of metabolite regulation, oxidative stress, and mitochondrial dysfunction that has direct implications for human infertility, premature reproductive aging due to oxidative stress, and gonadoprotection.

Eriodictyol alleviates lipopolysaccharide-triggered oxidative stress and synaptic dysfunctions in BV-2 microglial cells and mouse brain

Oxidative stress takes part in the development of the neurodegenerative disease. Eriodictyol, a flavonoid, commonly presents in citrus fruits, which was well-known for its various bioactivities. The purpose of this study was to investigate the neuroprotective effects of eriodictyol on lipopolysaccharide (LPS)-induced neuroinflammation, oxidative stress, synaptic dysfunctions, and the potential mechanisms involved. We found that eriodictyol explicitly restored LPS-triggered the decrease of cell viability and the mitochondrial potential as well as inflammation responses via mitogen-activated protein kinases (MAPKs) and nuclear factor κB (NF-κB) pathways regulated by reactive oxygen species (ROS). Besides, eriodictyol alleviated LPS-induced oxidative stress via NF-E2-Related factor2/Kelch-like ECH-associated protein 1 (Nrf2/Keap1) pathway in vivo and in vitro. Furthermore, eriodictyol reduced LPS-elicited synaptic dysfunctions via increasing the expression of silent information regulator 1 (Sirt1). Overall, eriodictyol protects LPS-triggered oxidative stress, neuroinflammation, and synaptic dysfunctions partially through MAPKs, NF-κB mediated by ROS, Sirt1, and Nrf2/Keap1 signal pathways, which further supports that eriodictyol is a potentially nutritional preventive strategy for oxidative stress-related neurodegenerative diseases.

Up-regulation of P-gp via NF-κB activation confers protection against oxidative damage in the retinal pigment epithelium cells

Dysfunction of retinal pigment epithelial (RPE) cells has been associated with the pathogenesis of age-related macular degeneration in relation to increased oxidative stress, subsequent mitochondrial dysfunction and cell death. Permeability-glycoprotein (P-gp), encoded by the multidrug resistance 1 gene (MDR1), is an active efflux pump involved in cell homeostasis and nuclear factor κB (NF-κB) shows potential involvement in P-gp regulation due to its binding to the promoter domains of MDR1 gene. This study sought to determine the role of P-gp expression regulated by NF-κB in RPE cells during oxidative stress. The human RPE D407 cells were exposed to increasing concentrations of hydrogen peroxide (H₂O₂) for 24 h. The small-interfering RNA (siRNA) transfection was used to down-regulate P-gp and NF-κB, and the expressions of P-gp and NF-κB p65 were determined by quantitative real-time PCR, western blot and immunofluorescence. The activity of NF-κB was detected by luciferase reporter assay. Mitochondrial membrane potential and cell death rate were detected by flow cytometry. We found that H₂O₂ exposure caused increasing rate of cell death and induced an elevated expression of P-gp as well as NF-κB activation and nucleus translocation in D407 cells. Inhibiting or silencing NF-κB led to a decrease in the oxidative-induced expression of P-gp. Down-regulation of P-gp by siRNA transfection further impaired the mitochondrial membrane potential and cell death rate in oxidative cells. Moreover, inhibition/knockdown of NF-κB decreased the high rate of cell death caused by H₂O₂. In conclusion, P-gp can provide moderate cytoprotection for the human RPE cells by ameliorating the mitochondrial dysfunction and NF-κB activation may be a potential regulator of P-gp expression response to oxidative stress.

Sulforaphane from Cruciferous Vegetables: Recent Advances to Improve Glioblastoma Treatment

Sulforaphane (SFN), an isothiocyanate (ITC) derived from cruciferous vegetables, particularly broccoli and broccoli sprouts, has been widely investigated due to its promising health-promoting properties in disease, and low toxicity in normal tissue. Although not yet fully understood, many mechanisms of anticancer activity at each step of cancer development have been attributed to this ITC. Given the promising data available regarding SFN, this review aimed to provide an overview on the potential activities of SFN related to the cellular mechanisms involved in glioblastoma (GBM) progression. GBM is the most frequent malignant brain tumor among adults and is currently an incurable disease due mostly to its highly invasive phenotype, and the poor efficacy of the available therapies. Despite all efforts, the median overall survival of GBM patients remains approximately 1.5 years under therapy. Therefore, there is an urgent need to provide support for translating the progress in understanding the molecular background of GBM into more complex, but promising therapeutic strategies, in which SFN may find a leading role.

Leaky brain in neurological and psychiatric disorders: Drivers and consequences

BACKGROUND

The blood-brain barrier acts as a highly regulated interface; its dysfunction may exacerbate, and perhaps initiate, neurological and neuropsychiatric disorders.

METHODS

In this narrative review, focussing on redox, inflammatory and mitochondrial pathways and their effects on the blood-brain barrier, a model is proposed detailing mechanisms which might explain how increases in blood-brain barrier permeability occur and can be maintained with increasing inflammatory and oxidative and nitrosative stress being the initial drivers.

RESULTS

Peripheral inflammation, which is causatively implicated in the pathogenesis of major psychiatric disorders, is associated with elevated peripheral pro-inflammatory cytokines, which in turn cause increased blood-brain barrier permeability. Reactive oxygen species, such as superoxide radicals and hydrogen peroxide, and reactive nitrogen species, such as nitric oxide and peroxynitrite, play essential roles in normal brain capillary endothelial cell functioning; however, chronically elevated oxidative and nitrosative stress can lead to mitochondrial dysfunction and damage to the blood-brain barrier. Activated microglia, redox control of which is mediated by nitric oxide synthases and nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, secrete neurotoxic molecules such as reactive oxygen species, nitric oxide, prostaglandin, cyclooxygenase-2, quinolinic acid, several chemokines (including monocyte chemoattractant protein-1 [MCP-1], C-X-C motif chemokine ligand 1 [CXCL-1] and macrophage inflammatory protein 1α [MIP-1α]) and the pro-inflammatory cytokines interleukin-6, tumour necrosis factor-α and interleukin-1β, which can exert a detrimental effect on blood-brain barrier integrity and function. Similarly, reactive astrocytes produce neurotoxic molecules such as prostaglandin E2 and pro-inflammatory cytokines, which can cause a 'leaky brain'.

CONCLUSION

Chronic inflammatory and oxidative and nitrosative stress is associated with the development of a 'leaky gut'. The following evidence-based approaches, which address the leaky gut and blood-brain barrier dysfunction, are suggested as potential therapeutic interventions for neurological and neuropsychiatric disorders: melatonin, statins, probiotics containing Bifidobacteria and Lactobacilli, N-acetylcysteine, and prebiotics containing fructo-oligosaccharides and galacto-oligosaccharides.

Characterization of Hit Compounds Identified from High-throughput Screening for their Effect on Blood-brain Barrier Integrity and Amyloid-β Clearance: In Vitro and In Vivo Studies

In Alzheimer's disease (AD) the blood-brain barrier (BBB) is compromised, thus therapeutic targeting of the BBB to enhance its integrity and function could be a unique approach to treat, slow or hold the progression of AD. Recently, we have developed an in vitro high-throughput screening assay to screen for compounds that increase the integrity of a cell-based BBB model. Results from primary screen identified multiple hit compounds that enhanced the monolayer integrity. Herein, further characterization of selected hit compounds, namely 8-bromoguanosine cyclic monophosphate, JW74, 1,10-phenanthroline monohydrate, SB216763 and α-tocopherol was performed. Compounds were subjected to concentration-dependent studies to determine their EC50 and potency to enhance the cell-based model integrity by the Lucifer Yellow permeability and amyloid-beta (Aβ) transport across the monolayer. The compounds demonstrated different EC50s to enhance the monolayer integrity ranging from 0.4 to 12.8 µM, and different effect on enhancing Aβ transport with highest transport observed for α-tocopherol (2.2-fold increase). Such effects were associated with increased levels of tight junction proteins such as claudin-5 and/or ZO-1, and Aβ major transport proteins LRP1 and P-glycoprotein. In vivo studies for α-tocopherol were performed in AD mouse model; consistent with the in vitro results α-tocopherol significantly increased BBB integrity measured by IgG extravasation, and reduced brain Aβ levels. In conclusion, findings support our developed cell-based BBB model as a functional predictive in vivo tool to select hit compounds, and suggest that enhancing BBB tightness and function has the potential to reduce Aβ pathology associated with AD.