Brain Distribution Research Articles

DDEL-03. PHYSIOLOGICALLY BASED PHARMACOKINETIC (PBPK) MODELING OF HETEROGENEOUS DRUG PENETRATION INTO THE HUMAN BRAIN AND GLIOBLASTOMA

Abstract BACKGROUD Insufficient penetration of potentially effective therapeutic agents across the human blood-brain barrier (BBB) is a hurdle to the effective treatment of brain cancer. The BBB in glioblastoma is disrupted to varying extents. This study was to develop a PBPK model platform for prediction of heterogenous drug penetration into the human brain and glioblastoma. METHODS A 7-compartment CNS (7-CNS) PBPK model platform was developed to predict drug concentrations in the brain blood, brain parenchyma, cranial CSF, spinal CSF, and 3 tumor compartments representing infiltrating tumor (T1) with a slightly disrupted BBB, bulk tumor (T2) with a leaky BBB, and necrotic core (T3) with no blood vessels. The model accounted for brain/tumor general anatomy and regional pathophysiological differences. Drug transfer and fluid balance between compartments were described by differential equations. Simulations were performed using R programming. The model was verified by comparisons of predicted and observed tumor PK data of ribociclib and abemaciclib in glioblastoma patients. RESULTS For ribociclib, the model-predicted mean unbound drug brain-to-plasma ratio (Kp,uu) was 0.17, 2.2, 8.2, 24.9 in normal brain, T1, T2, and T3, respectively; the predicted Kp,uu in T1 and T2 was consistent with observed Kp,uu in non-enhancing (median, 2.0) and enhancing tumors (median, 10.1) from 12 patients. For abemaciclib, the predicted mean Kp,uu was 0.88, 1.4, 6.2, and 3.1 in normal brain, T1, T2, and T3, respectively; the predicted Kp,uu in T1 and T2 agreed with observed Kp,uu in non-enhancing (median, 2.1) and enhancing tumors (median, 7.2) from 38 patients. CONCLUSION The developed PBPK model platform well predicts heterogeneous drug penetration and distribution in normal human brain and different regions of glioblastoma, as verified by ribociclib and abemaciclib. It provides a mechanism-based computational modeling tool to assist the development and design of improved drugs and dosing regimens for more effective treatment of glioblastoma.

Oropharyngeal aspirated Ag/TiO2 nanohybrids: Transformation, distribution and toxicity

The wide application of Ag-loaded TiO2 nanohybrids photocatalysts on environment and energy increases the lung exposure risk to humans. Ag/TiO2 nanohybrids inhalation can cause pulmonary toxicity, and there are concerns about whether the loaded silver can be released and cause toxic effects on extrapulmonary organs. Therefore, in this study, the possible biotransformation, biodistribution, and toxicity of oropharyngeal aspirated Ag/TiO2 nanohybrids were investigated first time in vitro and in vivo to answer this question. Firstly, the results of biotransformation showed that the ultrafine silver nanoparticles (~3.5 nm, 2 w/w%) loaded on the surface of nano-TiO2 (~25 nm) could agglomerate and release in Gamble's solution, and the hydrodynamic diameter of the nanohybrids agglomerates increased from about 200 nm to 1 μm. Furthermore, after exposure 10 mg/kg Ag/TiO2 nanohybrids to C57BL/6 J male mice by oropharyngeal aspiration weekly, the biodistribution results showed that the released silver could result in blood, liver, and brain distribution within 28 d. Finally, body weight, organ coefficient, blood biochemical indicators of liver and kidney function, and pathological images demonstrated that although silver could release and lead to extrapulmonary organ distribution, it did not cause obvious extrapulmonary organ damage. The original lung was still the main toxicity and accumulation target organ of Ag/TiO2 nanohybrids, which mainly manifested as the pro-inflammatory and pro-fibrotic effects that should be focused on in the future. Therefore, this study is of great significance in evaluating the safety of Ag-loaded TiO2 nanoparticles and predicting their toxic mechanisms.

Revisiting the outcome of adult wild-type Htt inactivation in the context of HTT-lowering strategies for Huntington's disease.

Huntingtin-lowering strategies are central to therapeutic approaches for Huntington's disease. Recent studies reported the induction of age- and cell type-specific phenotypes by conditional huntingtin knockout, but these experimental conditions did not precisely mimic huntingtin-lowering or gene-editing conditions in terms of the cells targeted and brain distribution, and no transcriptional profiles were provided. Here, we used the adeno-associated delivery system commonly used in CNS gene therapy programmes and the self-inactivating KamiCas9 gene-editing system to investigate the long-term consequences of wild-type mouse huntingtin inactivation in adult neurons and, thus, the feasibility and safety of huntingtin inactivation in these cells. Behavioural and neuropathological analyses and single-nuclei RNA sequencing indicated that huntingtin editing in 77% of striatal neurons and 16% of cortical projecting neurons in adult mice induced no behavioural deficits or cellular toxicity. Single-nuclei RNA sequencing in 11.5-month-old animals showed that huntingtin inactivation did not alter striatal-cell profiles or proportions. Few differentially expressed genes were identified and Augur analysis confirmed an extremely limited response to huntingtin inactivation in all cell types. Our results therefore indicate that wild-type huntingtin inactivation in adult striatal and projection neurons is well tolerated in the long term.

Dissimilar Effect of P-Glycoprotein and Breast Cancer Resistance Protein Inhibition on the Distribution of Erlotinib to the Retina and Brain in Humans and Mice.

P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) are two ATP-binding cassette efflux transporters that are coexpressed at the human blood-brain barrier (BBB) and blood-retina barrier (BRB). While pharmacological inhibition of P-gp and/or BCRP results in increased brain distribution of dual P-gp/BCRP substrate drugs, such as the tyrosine kinase inhibitor erlotinib, the effect of P-gp and/or BCRP inhibition on the retinal distribution of such drugs has hardly been investigated. In this study, we used positron emission tomography (PET) imaging to assess the effect of transporter inhibition on the distribution of [11C]erlotinib to the human retina and brain. Twenty two healthy volunteers underwent two PET scans after intravenous (i.v.) injection of a microdose (<5 μg) of [11C]erlotinib, a baseline scan, and a second scan either with concurrent i.v. infusion of tariquidar to inhibit P-gp (n = 5) or after oral intake of single ascending doses of erlotinib (300 mg, 650 mg, or 1000 mg, n = 17) to saturate erlotinib transport. In addition, transport of [3H]erlotinib to the retina and brain was assessed in mice by in situ carotid perfusion under various drug transporter inhibition settings. In comparison to the baseline PET scan, coadministration of tariquidar or erlotinib led to a significant decrease of [11C]erlotinib total volume of distribution (VT) in the human retina by -25 ± 8% (p ≤ 0.05) and -41 ± 16% (p ≤ 0.001), respectively. In contrast, erlotinib intake led to a significant increase in [11C]erlotinib VT in the human brain (+20 ± 16%, p ≤ 0.001), while administration of tariquidar did not result in any significant changes. In situ carotid perfusion experiments showed that both P-gp and BCRP significantly limit the distribution of erlotinib to the mouse retina and brain but revealed a similar discordant effect at the mouse BRB and BBB following co-perfusion with tariquidar and erlotinib as in humans. Co-perfusion with prototypical inhibitors of solute carrier transporters did not reveal a significant contribution of organic cation transporters (e.g., OCTs and OCTNs) and organic anion-transporting polypeptides (e.g., OATP2B1) to the retinal and cerebral distribution of erlotinib. In conclusion, we observed a dissimilar effect after P-gp and/or BCRP inhibition on the retinal and cerebral distribution of [11C]erlotinib. The exact mechanism for this discrepancy remains unclear but may be related to the function of an unidentified erlotinib uptake carrier sensitive to tariquidar inhibition at the BRB. Our study highlights the great potential of PET to study drug distribution to the human retina and to assess the functional impact of membrane transporters on ocular drug distribution.

Interaction of amisulpride with GLUT1 at the blood-brain barrier. Relevance to Alzheimer's disease.

Blood-brain barrier (BBB) dysfunction may be involved in the increased sensitivity of Alzheimer's disease (AD) patients to antipsychotics, including amisulpride. Studies indicate that antipsychotics interact with facilitated glucose transporters (GLUT), including GLUT1, and that GLUT1 BBB expression decreases in AD. We tested the hypotheses that amisulpride (charge: +1) interacts with GLUT1, and that BBB transport of amisulpride is compromised in AD. GLUT1 substrates, GLUT1 inhibitors and GLUT-interacting antipsychotics were identified by literature review and their physicochemical characteristics summarised. Interactions between amisulpride and GLUT1 were studied using in silico approaches and the human cerebral endothelial cell line, hCMEC/D3. Brain distribution of [3H]amisulpride was determined using in situ perfusion in wild type (WT) and 5xFamilial AD (5xFAD) mice. With transmission electron microscopy (TEM) we investigated brain capillary degeneration in WT mice, 5xFAD mice and human samples. Western blots determined BBB transporter expression in mouse and human. Literature review revealed that, although D-glucose has no charge, charged molecules can interact with GLUT1. GLUT1 substrates are smaller (184.95±6.45g/mol) than inhibitors (325.50±14.40g/mol) and GLUT-interacting antipsychotics (369.38±16.04). Molecular docking showed beta-D-glucose (free energy binding: -15.39kcal/mol) and amisulpride (-29.04kcal/mol) interact with GLUT1. Amisulpride did not affect [14C]D-glucose hCMEC/D3 accumulation. [3H]amisulpride uptake into the brain (except supernatant) of 5xFAD mice compared to WT remained unchanged. TEM revealed brain capillary degeneration in human AD. There was no difference in GLUT1 or P-glycoprotein BBB expression between WT and 5xFAD mice. In contrast, caudate P-glycoprotein, but not GLUT1, expression was decreased in human AD capillaries versus controls. This study provides new details about the BBB transport of amisulpride, evidence that amisulpride interacts with GLUT1 and that BBB transporter expression is altered in AD. This suggests that antipsychotics could potentially exacerbate the cerebral hypometabolism in AD. Further research into the mechanism of amisulpride transport by GLUT1 is important for improving antipsychotics safety.

Distribution of morphine and methadone to the brain in a developmental chicken embryo model

The use and/or misuse of opioids by pregnant women would expose the fetuses to these drugs during critical stages of development with serious effects for the newborn, like the neonatal abstinence syndrome (NAS). We have revisited an established chicken model for NAS to describe the distribution of morphine and methadone to the brain and explore its validity as a valuable alternative to rodent models. For this purpose, chicken eggs were injected with a single dose of 10 mg/kg or 20 mg/kg morphine or 20 mg/kg methadone onto the chorioallantoic membrane (CAM) on embryonal day 13. Whole brains and lungs were harvested and the concentrations of morphine, methadone and their subsequent metabolites (morphine-3-glucuronide and EDDP, respectively) determined in the brain and lungs at different time points using LC-MS/MS. Morphine and methadone, as well as their metabolites, were detected both in the brain and lungs, with significantly higher concentrations in the lungs. Pharmacokinetic modelling showed that the distribution of morphine to the brain followed a first-order absorption with transit compartments and linear elimination, with concentrations linearly dependent on dose. Moreover, methadone, but not morphine, reduced μ receptor (the main morphine receptor) binding, which can be of relevance for opioid tolerance. The present study is the first to report the brain distribution of morphine, which can be described by standard pharmacokinetic processes, and methadone in the developing chicken embryo. The present findings supplement the already established model and support the use of this chicken model to study NAS.

Enhanced antidepressant effects of BDNF-quercetin alginate nanogels for depression therapy

BackgroundBrain-derived neurotrophic factor (BDNF) with neuronic development and function is a promising therapeutic agent for treating depressive disorder, according to the neurotrophin hypothesis. However, the delivery of BDNF into the brain is not easy as these large protein molecules cannot efficiently cross the blood-brain barrier (BBB) and easily suffer oxidative damage in vivo. Therefore, the quercetin-based alginate nanogels (quercetin nanogels) loaded with BDNF have been developed, which could efficiently bypass the BBB via the nose-to-brain pathway and protect BDNF from oxidative damage, providing an effective route for the therapy of depressive disorders by intranasal delivery.ResultsQuercetin nanogels exhibited uniform size distribution, excellent biocompatibility, and potent antioxidant and anti-inflammatory activities. Quercetin nanogels in the thermosensitive gel achieved sustained and controlled release of BDNF with non-Fick’s diffusion, exhibited rapid brain distribution, and achieved nearly 50-fold enhanced bioavailability compared to oral quercetin. Quercetin nanogels as a therapeutic drug delivery carrier exerted antidepressant effects on reserpine-induced rats, effectively delivered BDNF to reverse despair behavior in stress-induced mice, and exhibited antidepressant effects on chronic mild unpredictable stimulation (CUMS) rats. These antidepressant effects of BDNF-Quercetin nanogels for CUMS rats are associated with the regulation of the glutamatergic system, PI3K-Akt, and BDNF-TrkB signaling pathway.ConclusionsIn this study, we provide a promising strategy for brain delivery of BDNF for treating depressive disorders, effectively achieved through combining quercetin nanogels and intranasal administration.

N-glycans show distinct spatial distribution in mouse brain.

The development and function of the brain requires N-linked glycosylation of proteins, which is a ubiquitous modification in the secretory pathway. N-glycans have a distinct composition and undergo tight regulation in the brain, but the spatial distribution of these structures remains relatively unexplored. Here, we systematically employed carbohydrate binding lectins with differing specificities to various classes of N-glycans and appropriate controls to identify glycan expression in multiple regions of the mouse brain. Lectins binding high-mannose-type N-glycans, the most abundant class of brain N-glycans, showed diffuse staining with some punctate structures observed on high magnification. Lectins binding specific motifs of complex N-glycans, including fucose and bisecting GlcNAc, showed more partitioned labeling, including to the synapse-rich molecular layer of the cerebellum. Understanding the spatial distribution of N-glycans across the brain will aid future studies of these critical protein modifications in development and disease of the brain.

Ginkgo biloba extract protects against depression-like behavior in mice through regulating gut microbial bile acid metabolism.

Depression is a mental disorder with high morbidity, disability and relapse rates. Ginkgo biloba extract (GBE), a traditional Chinese medicine, has a long history of clinical application in the treatment of cerebral and mental disorders, but the key mechanism remains incompletely understood. Here we showed that GEB exerted anti-depressant effect in mice through regulating gut microbial metabolism. GBE protected against unpredictable mild stress (UMS)-induced despair, anxiety-like and social avoidance behavior in mice without sufficient brain distribution. Fecal microbiome transplantation transmitted, while antibiotic cocktail abrogated the protective effect of GBE. Spatiotemporal bacterial profiling and metabolomics assay revealed a potential involvement of Parasutterella excrementihominis and the bile acid metabolite ursodeoxycholic acid (UDCA) in the effect of GBE. UDCA administration induced depression-like behavior in mice. Together, these findings suggest that GBE acts on gut microbiome-modulated bile acid metabolism to alleviate stress-induced depression.

Impact of a moderate decrease in the abundance of P-glycoprotein at the blood–brain barrier on the brain distribution of model P-glycoprotein substrates

Impact of a moderate decrease in the abundance of P-glycoprotein at the blood–brain barrier on the brain distribution of model P-glycoprotein substrates

A fast and accurate brain extraction method for CT head images

BackgroundBrain extraction is an essential prerequisite for the automated diagnosis of intracranial lesions and determines, to a certain extent, the accuracy of subsequent lesion recognition, location, and segmentation. Segmentation using a fully convolutional neural network (FCN) yields high accuracy but a relatively slow extraction speed.MethodsThis paper proposes an integrated algorithm, FABEM, to address the above issues. This method first uses threshold segmentation, closed operation, convolutional neural network (CNN), and image filling to generate a specific mask. Then, it detects the number of connected regions of the mask. If the number of connected regions equals 1, the extraction is done by directly multiplying with the original image. Otherwise, the mask was further segmented using the region growth method for original images with single-region brain distribution. Conversely, for images with multi-region brain distribution, Deeplabv3 + is used to adjust the mask. Finally, the mask is multiplied with the original image to complete the extraction.ResultsThe algorithm and 5 FCN models were tested on 24 datasets containing different lesions, and the algorithm’s performance showed MPA = 0.9968, MIoU = 0.9936, and MBF = 0.9963, comparable to the Deeplabv3+. Still, its extraction speed is much faster than the Deeplabv3+. It can complete the brain extraction of a head CT image in about 0.43 s, about 3.8 times that of the Deeplabv3+.ConclusionThus, this method can achieve accurate brain extraction from head CT images faster, creating a good basis for subsequent brain volume measurement and feature extraction of intracranial lesions.

P10.21.A THE ABCB1/ABCG2 INHIBITOR ELACRIDAR IS A MORE POTENT PHARMACOENHANCER COMPARED TO TARIQUIDAR FOR TREATMENT OF INTRACRANIAL TUMORS WITH SMALL MOLECULE DRUGS

Abstract BACKGROUND The blood-brain barrier (BBB) is a major hurdle to successful pharmacotherapy of brain tumors. ABCB1 and ABCG2 are efflux transporters that are expressed in brain tumor vessels and reduce the uptake of many small molecule drugs. Elacridar and tariquidar are both dual ABCB1 and ABCG2 inhibitors. We aim to improve pharmacotherapy of brain cancer by concomitant use of potentially effective drugs with elacridar. Since tariquidar has mostly been used to assess the effects of ABC-transporters on brain uptake in human studies with PET tracers, we decided to compare both agents in our rodent models. MATERIAL AND METHODS We used Abcg2;Abcb1a/b double knockout (DKO), Abcb1a/b KO, Abcg2 KO and wild-type mice receiving a cocktail of 7 model drugs at a fixed low dose in combination with elacridar or tariquidar at a range of doses. Drugs were given by 3-h infusion. DKO mice are the reference for complete inhibition, while single KO mice allow interrogation of the remaining transporter in case of dual substrate drugs. Brain and plasma levels were measured by LC-MS/MS. RESULTS Complete inhibition of Abcb1 by elacridar was achieved when the plasma level is about 1.0 μM. However, a much higher plasma level (&amp;gt;4 μM) of tariquidar was needed. Inhibition of Abcg2 was more difficult. For erlotinib and palbociclib about 1.0 μM of elacridar was sufficient, but other more profound Abcg2 substrate drugs never reached the B/P ratios achieved in reference to DKO mice, even at 4 μM. Strikingly, tariquidar could not enhance the brain uptake of ABCG2-subtrate drugs in Abcb1a/b KO mice. The B/P ratio of elacridar in DKO mice was 6. Elacridar improved its own brain distribution in WT mice, achieving steady-state B/P ratios at plasma level above 1.4 μM. The B/P ratio of tariquidar in DKO mice was about 2, while in WT and Abcb1a/b KO mice was 0.3 and did not increase even at plasma concentration &amp;gt;8 μM. Only in Abcg2 KO mice, the B/P ratio increased to levels of DKO mice at tariquidar plasma levels of &amp;gt; 6 μM. CONCLUSION Elacridar is a much more potent inhibitor of Abcb1a/b and Abcg2 at the BBB. Elacridar can act as a pharmaco-enhancer of ABCB1 substrate drugs and weaker ABCG2 substrates. Tariquidar will enhance the brain penetration of ABCB1 substrates, but full inhibition is only achieved at levels above those reported in human subjects. The efflux of tariquidar by Abcg2 at the BBB severely compromises the usefulness of tariquidar as a pharmaco-enhancer for brain delivery.

Urolithins: A Prospective Alternative against Brain Aging.

The impact of host-microbiome interactions on cognitive health and disease has received increasing attention. Microbial-derived metabolites produced in the gut are one of crucial mechanisms of the gut-brain axis interaction, showing attractive perspectives. Urolithins (Uros) are gut microbial-derived metabolites of ellagitannins and ellagic acid, whose biotransformation varies considerably between individuals and decreases greatly with age. Recently, accumulating evidence has suggested that Uros may have specific advantages in preventing brain aging including favorable blood-brain barrier permeability, selective brain distribution, and increasingly supporting data from preclinical and clinical studies. However, the usability of Uros in diagnosis, prevention, and treatment of neurodegenerative diseases remains elusive. In this review, we aim to present the comprehensive achievements of Uros in age-related brain dysfunctions and neurodegenerative diseases and discuss their prospects and knowledge gaps as functional food, drugs, or biomarkers against brain aging.

Design and development of donepezil hydrochloride loaded nanostructured lipid carriers for efficient management of Alzheimer’s disease

Objective The primary objective of this study was to develop nanostructured lipid carriers of donepezil hydrochloride (DNZ HCl) for effective management of Alzheimer’s disease (AD). Significance Intranasal administration of DNZ NLC containing Nigella sativa (NS) oil as a liquid lipid may significantly improve nasal penetration and deliver the drug directly to the brain avoiding blood brain barrier (BBB). Method High pressure homogenization was used to prepare nanostructured lipid carriers (NLCs), followed by ultrasonication. Glyceryl monostearate (GMS), Tween 80, and Poloxamer 407 were used as solid lipid, surfactant and co-surfactant respectively, whereas, Nigella sativa oil was used as a liquid lipid. Result The particle size, polydispersity index and zeta potential were found to be 107.4 ± 2.64 nm, 0.25 ± 0.04 and −41.7 mV. The entrapment efficiency and drug content were found to be 70.20% and 89.05% respectively. After intranasal administration of Donepezil hydrochloride (DNZ HCl) loaded NLC’s, the maximum concentrations (Cmax) of 4.597 µg/mL in brain and 2.2583 µg/mL in blood was achieved after 1 h (Tmax). Conclusion The formulated DNZ HCl loaded NLCs significantly improved nasal penetration and enhanced drug distribution in brain resulting in a potentially effective intranasal drug delivery system for the effective management of Alzheimer’s disease.

Simulation calculation of electric field distribution in the rat brain irradiated by electromagnetic pulses

Based on the spectrum distribution of electromagnetic pulses (EMPs), we constructed a dispersive electromagnetic model of rats with a fine division of tissues and organs and calculated the internal electric field distribution in the rat brain exposed to EMPs. The results showed that EMP radiation was capable of generating electric field distribution with good uniformity in the rat brain and that the peak field intensity in the rat brain was about 1/250 of that in the spatial domain. The electric field in the cerebral cortex was slightly higher than that in the deep hippocampus, striatum, and thalamus, and it was probably the lowest in the hypothalamus. In the cortex, the electric field was low in the prefrontal cortex, while it was relatively high in the parietal and temporal lobes near the middle and at the back of the brain. The data provide a theoretical quantitative basis for establishment of the dose–effect relationship between the electric field in the rat brain and biological effects of the pulse. In addition, it serves as a reference for simulation calculation of the effect of EMPs in living organisms.

In vivo brain distribution study of dexamethasone encapsulated in polymeric and albumin-based nanocarriers

In vivo brain distribution study of dexamethasone encapsulated in polymeric and albumin-based nanocarriers

How Much is Enough? Impact of Efflux Transporters on Drug delivery Leading to Efficacy in the Treatment of Brain Tumors.

The lack of effective chemotherapeutic agents for the treatment of brain tumors is a serious unmet medical need. This can be attributed, in part, to inadequate delivery through the blood-brain barrier (BBB) and the tumor-cell barrier, both of which have active efflux transporters that can restrict the transport of many potentially effective agents for both primary and metastatic brain tumors. This review briefly summarizes the components and function of the normal BBB with respect to drug penetration into the brain and the alterations in the BBB due to brain tumor that could influence drug delivery. Depending on what is rate-limiting a compound's distribution, the limited permeability across the BBB and the subsequent delivery into the tumor cell can be greatly influenced by efflux transporters and these are discussed in some detail. Given these complexities, it is necessary to quantify the extent of brain distribution of the active (unbound) drug to compare across compounds and to inform potential for use against brain tumors. In this regard, the metric, Kp,uu, a brain-to-plasma unbound partition coefficient, is examined and its current use is discussed. However, the extent of active drug delivery is not the only determinant of effective therapy. In addition to Kp,uu, drug potency is an important parameter that should be considered alongside drug delivery in drug discovery and development processes. In other words, to answer the question - How much is enough? - one must consider how much can be delivered with how much needs to be delivered.

Novel nasal niosomes loaded with lacosamide and coated with chitosan: A possible pathway to target the brain to control partial-onset seizures

This work aimed to develop and produce lacosamide-loaded niosomes coated with chitosan (LCA-CTS-NSM) using a thin-film hydration method and the Box-Behnken design. The effect of three independent factors (Span 60 amount, chitosan concentration, and cholesterol amount) on vesicle size, entrapment efficiency, zeta potential, and cumulative release (8 h) was studied. The optimal formulation of LCA-CTS-NSM was chosen from the design space and assessed for morphology, in vitro release, nasal diffusion, stability, tolerability, and in vivo biodistribution for brain targeting after intranasal delivery. The vesicle size, entrapment, surface charge, and in vitro release of the optimal formula were found to be 194.3 nm, 58.3%, +35.6 mV, and 81.3%, respectively. Besides, it exhibits sustained release behavior, enhanced nasal diffusion, and improved physical stability. Histopathological testing revealed no evidence of toxicity or structural damage to the nasal mucosa. It demonstrated significantly more brain distribution than the drug solution. Overall, the data is encouraging since it points to the potential for non-invasive intranasal administration of LCA as an alternative to oral or parenteral routes.

Polystyrene Microplastics Exacerbate Systemic Inflammation in High-Fat Diet-Induced Obesity.

Microplastics (MPs) are recognized as environmental pollutants with potential implications for human health. Considering the rapid increase in obesity rates despite stable caloric intake, there is a growing concern about the link between obesity and exposure to environmental pollutants, including MPs. In this study, we conducted a comprehensive investigation utilizing in silico, in vitro, and in vivo approaches to explore the brain distribution and physiological effects of MPs. Molecular docking simulations were performed to assess the binding affinity of three plastic polymers (ethylene, propylene, and styrene) to immune cells (macrophages, CD4+, and CD8+ lymphocytes). The results revealed that styrene exhibited the highest binding affinity for macrophages. Furthermore, in vitro experiments employing fluorescence-labeled PS-MPs (fPS-MPs) of 1 μm at various concentrations demonstrated a dose-dependent binding of fPS-MPs to BV2 murine microglial cells. Subsequent oral administration of fPS-MPs to high-fat diet-induced obese mice led to the co-existence of fPS-MPs with immune cells in the blood, exacerbating impaired glucose metabolism and insulin resistance and promoting systemic inflammation. Additionally, fPS-MPs were detected throughout the brain, with increased activation of microglia in the hypothalamus. These findings suggest that PS-MPs significantly contribute to the exacerbation of systemic inflammation in high-fat diet-induced obesity by activating peripheral and central inflammatory immune cells.

TDP-43 forms amyloid filaments with a distinct fold in type A FTLD-TDP.

The abnormal assembly of TAR DNA-binding protein 43 (TDP-43) in neuronal and glial cells characterizes nearly all cases of amyotrophic lateral sclerosis (ALS) and around half of cases of frontotemporal lobar degeneration (FTLD)1,2. A causal role for TDP-43 assembly in neurodegeneration is evidenced by dominantly inherited missense mutations in TARDBP, the gene encoding TDP-43, that promote assembly and give rise to ALS and FTLD3-7. At least four types (A-D) of FTLD with TDP-43 pathology (FTLD-TDP) are defined by distinct brain distributions of assembled TDP-43 and are associated with different clinical presentations of frontotemporal dementia8. We previously showed, using cryo-electronmicroscopy, that TDP-43 assembles into amyloid filaments in ALS and type B FTLD-TDP9. However, the structures of assembled TDP-43 in FTLD without ALS remained unknown. Here we report the cryo-electron microscopy structures of assembled TDP-43 from the brains of three individuals with the most common type of FTLD-TDP, type A. TDP-43 formed amyloid filaments with a new fold that was the same across individuals, indicating that this fold may characterize type A FTLD-TDP. The fold resembles a chevron badge and is unlike the double-spiral-shaped fold of ALS and type B FTLD-TDP, establishing that distinct filament folds of TDP-43 characterize different neurodegenerative conditions. The structures, in combination with mass spectrometry, led to the identification of two new post-translational modifications of assembled TDP-43, citrullination and monomethylation of R293, and indicate that they may facilitate filament formation and observed structural variation in individual filaments. The structures of TDP-43 filaments from type A FTLD-TDP will guide mechanistic studies of TDP-43 assembly, as well as the development of diagnostic and therapeutic compounds for TDP-43 proteinopathies.