Pharmacokinetic analysis of antiviral drug ritonavir across the blood-brain barrier and its interaction with Scutellaria baicalensis using multisite microdialysis in rats

Ritonavir, an excellent inhibitor of CYP3A4, has recently been combined with nirmatrelvir to form Paxlovid for the treatment of severe acute respiratory syndrome coronavirus 2 infections. The root of Scutellaria baicalensis Georgi (S. baicalensis), a traditional Chinese medicinal (TCM) herb commonly used to treat heat/inflammation in the lung and digestive tracts, which are major organs targeted by viral infections, contains flavones that can influence the CYP3A metabolism pathway. To investigate the ability of ritonavir to cross the bloodbrain barrier (BBB) and its potential herb-drug interactions with an equivalent TCM clinical dose of S. baicalensis, multisite microdialysis coupled with an LCMS/MS system was developed using rat model. Pretreatment with S. baicalensis extract for 5 days, which contains less flavones than those used in previous studies, had a significant influence on ritonavir, resulting in a 2-fold increase in the total concentration of flavones in the blood and brain. Treatment also boosted the maximum blood concentration of flavones by 1.5-fold and the maximum brain concentration of flavones by 2-fold, all the while exerting no noticeable influence on the transfer ratio across the bloodbrain barrier. These experimental results demonstrated that the use of a typical traditional Chinese medicinal dose of S. baicalensis is sufficient to influence the metabolic pathway and synergistically increase the concentration of ritonavir in rats.

Inhibiting ferroptosis in brain microvascular endothelial cells: A potential strategy to mitigate polystyrene nanoplastics‒induced blood‒brain barrier dysfunction

Polystyrene nanoplastics (PS-NPs), a group of ubiquitous pollutants, may injure the central nervous system through the blood‒brain barrier (BBB). However, whether exposure to PS-NPs contributes to BBB disruption and the underlying mechanisms are still unclear. In vivo, we found that PS-NPs (25 mg/kg BW) could significantly increase BBB permeability in mice and downregulate the distribution of the tight junction-associated protein zona occludens 1 (ZO-1) in brain microvascular endothelial cells (BMECs). Using an in vitro BBB model, exposure to PS-NPs significantly reduced the transendothelial electrical resistance and altered ZO-1 expression and distribution in a dose-dependent manner. RNA-seq analysis and functional investigations were used to investigate the molecular pathways involved in the response to PS-NPs. The results revealed that the ferroptosis and glutathione metabolism signaling pathways were related to the disruption of the BBB model caused by the PS-NPs. PS-NPs treatment promoted ferroptosis in bEnd.3 cells by inducing disordered glutathione metabolism in addition to Fe2+ and lipid peroxide accumulation, while suppressing ferroptosis with ferrostatin-1 (Fer-1) suppressed ferroptosis-related changes in bEnd.3 cells subjected to PS-NPs. Importantly, Fer-1 alleviated the decrease in ZO-1 expression in bEnd.3 cells and the exacerbation of BBB damage induced by PS-NPs. Collectively, our findings suggest that inhibiting ferroptosis in BMECs may serve as a potential therapeutic target against BBB disruption induced by PS-NPs exposure.

Dahuang-Wumei decoction protects against hepatic encephalopathy in mice: Behavioural, biochemical, and molecular evidence

BACKGROUND

Disturbance of the blood‒brain barrier (BBB) and associated inflammatory responses are observed in patients with hepatic encephalopathy (HE) and can cause long-term complications. Dahuang-Wumei decoction (DWD) is a renowned traditional Chinese herbal medicine with a long history of clinical use and has been widely employed as an effective treatment for hepatic encephalopathy (HE). Despite its established efficacy, the precise mechanisms underlying the therapeutic effects of DWD have not been fully elucidated.

PURPOSE

The present study aimed to comprehensively explore the potential effects and underlying molecular mechanisms of DWD on HE through an integrated investigation that included both in vivo and in vitro experiments.

METHODS

In the present study, carbon tetrachloride (CCl4) and thioacetamide (TAA) were used to establish an HE model in mice. The therapeutic effects of DWD on liver injury, fibrosis, brain injury, behaviour, and consciousness disorders were evaluated in vivo. C8-D1A and bEnd.3 cells were used to construct a BBB model in vitro. The effects of DWD on proinflammatory factor expression, BBB damage and the Wnt/β-catenin pathway were detected in vivo and in vitro.

RESULTS

Our results showed that DWD can improve liver injury and fibrosis and brain damage and inhibit neurofunctional and behavioural disorders in mice with HE. Afterwards, we found that DWD decreased the levels of proinflammatory factors and suppressed BBB disruption by increasing the levels of junction proteins in vivo and vitro. Further studies verified that the Wnt/β-catenin pathway may play a pivotal role in mediating the inhibitory effect of DWD on HE.

CONCLUSION

These results demonstrated that DWD can treat HE by preventing BBB disruption, and the underlying mechanisms involved were associated with the activation of the Wnt/β-catenin pathway and the inhibition of inflammatory responses.

Endothelial EGLN3-PKM2 signaling induces the formation of acute astrocytic barrier to alleviate immune cell infiltration after subarachnoid hemorrhage

BACKGROUND

Most subarachnoid hemorrhage (SAH) patients have no obvious hematoma lesions but exhibit blood-brain barrier dysfunction and vasogenic brain edema. However, there is a few days between blood‒brain barrier dysfunction and vasogenic brain edema. The present study sought to investigate whether this phenomenon is caused by endothelial injury induced by the acute astrocytic barrier, also known as the glial limitans.

METHODS

Bioinformatics analyses of human endothelial cells and astrocytes under hypoxia were performed based on the GEO database. Wild-type, EGLN3 and PKM2 conditional knock-in mice were used to confirm glial limitan formation after SAH. Then, the effect of endothelial EGLN3-PKM2 signaling on temporal and spatial changes in glial limitans was evaluated in both in vivo and in vitro models of SAH.

RESULTS

The data indicate that in the acute phase after SAH, astrocytes can form a temporary protective barrier, the glia limitans, around blood vessels that helps maintain barrier function and improve neurological prognosis. Molecular docking studies have shown that endothelial cells and astrocytes can promote glial limitans-based protection against early brain injury through EGLN3/PKM2 signaling and further activation of the PKC/ERK/MAPK signaling pathway in astrocytes after SAH.

CONCLUSION

Improving the ability to maintain glial limitans may be a new therapeutic strategy for improving the prognosis of SAH patients.

Subcellular trafficking and transcytosis efficacy of different receptor types for therapeutic antibody delivery at the blood‒brain barrier

Here, we report an experimental setup to benchmark different receptors for targeted therapeutic antibody delivery at the blood-brain barrier. We used brain capillary endothelial-like cells derived from induced pluripotent stem cells (hiPSC-BECs) as a model system and compared them to colon epithelial Caco-2 cells. This approach helped to identify favourable receptors for transport into the cell layer itself or for directing transport for transcytosis across the cell layer. The sorting receptors transferrin receptor and sortilin were shown to be efficient as antibody cargo receptors for intracellular delivery to the cell layer. In contrast, the cell surface receptors CD133 and podocalyxin were identified as static and inefficient receptors for delivering cargo antibodies. Similar to in vivo studies, the hiPSC-BECs maintained detectable transcytotic transport via transferrin receptor, while transcytosis was restricted using sortilin as a cargo receptor. Based on these findings, we propose the application of sortilin as a cargo receptor for delivering therapeutic antibodies into the brain microvascular endothelium.

Brain endothelial cell-derived extracellular vesicles with a mitochondria-targeting photosensitizer effectively treat glioblastoma by hijacking the blood‒brain barrier

Glioblastoma (GBM) is the most aggressive malignant brain tumor and has a high mortality rate. Photodynamic therapy (PDT) has emerged as a promising approach for the treatment of malignant brain tumors. However, the use of PDT for the treatment of GBM has been limited by its low blood‒brain barrier (BBB) permeability and lack of cancer-targeting ability. Herein, brain endothelial cell-derived extracellular vesicles (bEVs) were used as a biocompatible nanoplatform to transport photosensitizers into brain tumors across the BBB. To enhance PDT efficacy, the photosensitizer chlorin e6 (Ce6) was linked to mitochondria-targeting triphenylphosphonium (TPP) and entrapped into bEVs. TPP-conjugated Ce6 (TPP-Ce6) selectively accumulated in the mitochondria, which rendered brain tumor cells more susceptible to reactive oxygen species-induced apoptosis under light irradiation. Moreover, the encapsulation of TPP-Ce6 into bEVs markedly improved the aqueous stability and cellular internalization of TPP-Ce6, leading to significantly enhanced PDT efficacy in U87MG GBM cells. An in vivo biodistribution study using orthotopic GBM-xenografted mice showed that bEVs containing TPP-Ce6 [bEV(TPP-Ce6)] substantially accumulated in brain tumors after BBB penetration via transferrin receptor-mediated transcytosis. As such, bEV(TPP-Ce6)-mediated PDT considerably inhibited the growth of GBM without causing adverse systemic toxicity, suggesting that mitochondria are an effective target for photodynamic GBM therapy.

Hydrogen alleviated cognitive impairment and blood‒brain barrier damage in sepsis-associated encephalopathy by regulating ABC efflux transporters in a PPARα-dependent manner

Hydrogen (H₂) can protect against blood‒brain barrier (BBB) damage in sepsis-associated encephalopathy (SAE), but the mechanism is still unclear. We examined whether it is related to PPARα and its regulatory targets, ABC efflux transporters. After injection with DMSO/GW6471 (a PPARα inhibitor), the mice subjected to sham/caecal ligation and puncture (CLP) surgery were treated with H₂ for 60 min postoperation. Additionally, bEnd.3 cells were grown in DMSO/GW6471-containing or saline medium with LPS. In addition to the survival rates, cognitive function was assessed using the Y-maze and fear conditioning tests. Brain tissues were stained with TUNEL and Nissl staining. Additionally, inflammatory mediators (TNF-α, IL-6, HMGB1, and IL-1β) were evaluated with ELISA, and PPARα, ZO-1, occludin, VE-cadherin, P-gp, BCRP and MRP2 were detected using Western blotting. BBB destruction was assessed by brain water content and Evans blue (EB) extravasation. Finally, we found that H₂ improved survival rates and brain dysfunction and decreased inflammatory cytokines. Furthermore, H₂ decreased water content in the brain and EB extravasation and increased ZO-1, occludin, VE-cadherin and ABC efflux transporters regulated by PPARα. Thus, we concluded that H₂ decreases BBB permeability to protect against brain dysfunction in sepsis; this effect is mediated by PPARα and its regulation of ABC efflux transporters.

Biology of breast cancer brain metastases and novel therapies targeting the blood brain barrier: an updated review

Brain metastasis (BM) is a critical cause of morbidity and mortality in patients with breast cancer (BC). Compared with other cancer cells, BC cells (BCs) exhibit special features in the metastatic process. However, the underlying mechanisms are still unclear, especially the crosstalk between tumour cells and the microenvironment. To date, novel therapies for BM, including targeted therapy and antibody‒drug conjugates, have been developed. Due to an improved understanding of the blood‒brain barrier (BBB) and blood-tumour barrier (BTB), the development and testing of therapeutic agents in clinical phases have substantially increased. However, these therapies face a major challenge due to the low penetration of the BBB or BTB. As a result, researchers have increasingly focused on finding ways to promote drug penetration through these barriers. This review provides an updated overview of breast cancer brain metastases (BCBM) and summarizes the newly developed therapies for BCBM, especially drugs targeting the BBB or BTB.

CCL5/CCR5-mediated peripheral inflammation exacerbates blood‒brain barrier disruption after intracerebral hemorrhage in mice

BACKGROUND

Owing to metabolic disequilibrium and immune suppression, intracerebral hemorrhage (ICH) patients are prone to infections; according to a recent global analysis of stroke cases, approximately 10 million new-onset ICH patients had experienced concurrent infection. However, the intrinsic mechanisms underlying the effects of infection related peripheral inflammation after ICH remain unclear.

METHODS

Lipopolysaccharide (LPS) was intraperitoneally injected into ICH model mice to induce peripheral inflammation. Neurobehavioral deficits, blood‒brain barrier (BBB) disruption, and the expression of CCR5, JAK2, STAT3, and MMP9 were evaluated after treatment with recombinant CCL5 (rCCL5) (a CCR5 ligand), maraviroc (MVC) (an FDA-approved selective CCR5 antagonist), or JAK2 CRISPR plasmids.

RESULTS

Our study revealed that severe peripheral inflammation increased CCL5/CCR5 axis activation in multiple inflammatory cell types, including microglia, astrocytes, and monocytes, and aggravated BBB disruption and neurobehavioral dysfunction after ICH, possibly in part through the JAK2/STAT3 signaling pathway.

CONCLUSIONS

CCR5 might be a potential target for the clinical treatment of infection-induced exacerbation of BBB disruption following ICH.

Arsenic Induces Blood‒Brain Barrier Disruption and Regulates T Lymphocyte Subpopulation Differentiation in the Cerebral Cortex and Hippocampus Associated with the Nrf2 Pathway In Vivo

Increasing evidence has confirmed that the nervous system shows innate and adaptive immunity, which also participates in nerve damage. This study aimed to explore the neuroimmune imbalance induced by arsenic and its possible mechanism. Mice were exposed to NaAsO₂ (0, 5, 10, 25, and 50 mg/L) for 1 month by drinking water. Y-maze and Morris water maze tests revealed that arsenic impaired learning and memory. The optical density of Evans blue showed a marked dose-dependent increase in the brain, and the mRNA and protein levels of the BBB tight junctions (TJs), occludin at 25 and 50 mg/L arsenic, and claudin-5 at 50 mg/L arsenic, were markedly decreased in the cerebral cortex. Arsenic downregulated occludin and claudin-5 mRNA expression at 50 mg/L and protein expression at 25 and 50 mg/L in the hippocampus. Immunohistochemical staining showed that 50 mg/L arsenic increased corticocerebral and hippocampal CD3⁺ T, CD4⁺ T, and CD8⁺ T cells; CD4 and CD8 proteins were increased with 25 and 50 mg/L arsenic. Arsenic decreased the corticocerebral and hippocampal Th1, Th17, and regulatory Treg transcription factors T-bet, Rorγt, and Foxp3 and the cytokine IFN-γ, IL-17, and TGF-β mRNA levels and increased the Th2 transcription factor GATA3 and cytokine IL-4 mRNA levels. Moreover, arsenic enhanced the expression of nuclear factor E2-related factor (Nrf2) and its downstream enzymes heme oxygenase-1 (HO-1) and glutathione-S-transferase (GST). In conclusion, these results demonstrate that arsenic exposure induces BBB dysfunction and T lymphocyte infiltration and affects CD4⁺ T lymphocyte differentiation, which may be associated with Nrf2 activation.

Caveolin-1 accelerates hypoxia-induced endothelial dysfunction in high-altitude cerebral edema

Background

High-altitude cerebral edema (HACE) is a serious and potentially fatal brain injury that is caused by acute hypobaric hypoxia (HH) exposure. Vasogenic edema is the main pathological factor of this condition. Hypoxia-induced disruptions of tight junctions in the endothelium trigger blood‒brain barrier (BBB) damage and induce vasogenic edema. Nuclear respiratory factor 1 (NRF1) acts as a major regulator of hypoxia-induced endothelial cell injury, and caveolin-1 (CAV-1) is upregulated as its downstream gene in hypoxic endothelial cells. This study aimed to investigate whether CAV-1 is involved in HACE progression and the underlying mechanism.

Methods

C57BL/6 mice were exposed to HH (7600 m above sea level) for 24 h, and BBB injury was assessed by brain water content, Evans blue staining and FITC-dextran leakage. Immunofluorescence, transmission electron microscope, transendothelial electrical resistance (TEER), transcytosis assays, and western blotting were performed to confirm the role and underlying mechanism of CAV-1 in the disruption of tight junctions and BBB permeability. Mice or bEnd.3 cells were pretreated with MβCD, a specific blocker of CAV-1, and the effect of CAV-1 on claudin-5 internalization under hypoxic conditions was detected by immunofluorescence, western blotting, and TEER. The expression of NRF1 was knocked down, and the regulation of CAV-1 by NRF1 under hypoxic conditions was examined by qPCR, western blotting, and immunofluorescence.

Results

The BBB was severely damaged and was accompanied by a significant loss of vascular tight junction proteins in HACE mice. CAV-1 was significantly upregulated in endothelial cells, and claudin-5 explicitly colocalized with CAV-1. During the in vitro experiments, hypoxia increased cell permeability, CAV-1 expression, and claudin-5 internalization and downregulated tight junction proteins. Simultaneously, hypoxia induced the upregulation of CAV-1 by activating NRF1. Blocking CAV-1-mediated intracellular transport improved the integrity of TJs in hypoxic endothelial cells and effectively inhibited the increase in BBB permeability and brain water content in HH animals.

Conclusions

Hypoxia upregulated CAV-1 transcription via the activation of NRF1 in endothelial cells, thus inducing the internalization and autophagic degradation of claudin-5. These effects lead to the destruction of the BBB and trigger HACE. Therefore, CAV-1 may be a potential therapeutic target for HACE.

Gather wisdom to overcome barriers: Well-designed nano-drug delivery systems for treating gliomas

Due to the special physiological and pathological characteristics of gliomas, most therapeutic drugs are prevented from entering the brain. To improve the poor prognosis of existing therapies, researchers have been continuously developing non-invasive methods to overcome barriers to gliomas therapy. Although these strategies can be used clinically to overcome the blood‒brain barrier (BBB), the accurate delivery of drugs to the glioma lesions cannot be ensured. Nano-drug delivery systems (NDDS) have been widely used for precise drug delivery. In recent years, researchers have gathered their wisdom to overcome barriers, so many well-designed NDDS have performed prominently in preclinical studies. These meticulous designs mainly include cascade passing through BBB and targeting to glioma lesions, drug release in response to the glioma microenvironment, biomimetic delivery systems based on endogenous cells/extracellular vesicles/protein, and carriers created according to the active ingredients of traditional Chinese medicines. We reviewed these well-designed NDDS in detail. Furthermore, we discussed the current ongoing and completed clinical trials of NDDS for gliomas therapy, and analyzed the challenges and trends faced by clinical translation of these well-designed NDDS.

Recent advances in nanomedicines for the treatment of ischemic stroke

Ischemic stroke is a cerebrovascular disease normally caused by interrupted blood supply to the brain. Ischemia would initiate the cascade reaction consisted of multiple biochemical events in the damaged areas of the brain, where the ischemic cascade eventually leads to cell death and brain infarction. Extensive researches focusing on different stages of the cascade reaction have been conducted with the aim of curing ischemic stroke. However, traditional treatment methods based on antithrombotic therapy and neuroprotective therapy are greatly limited for their poor safety and treatment efficacy. Nanomedicine provides new possibilities for treating stroke as they could improve the pharmacokinetic behavior of drugs in vivo, achieve effective drug accumulation at the target site, enhance the therapeutic effect and meanwhile reduce the side effect. In this review, we comprehensively describe the pathophysiology of stroke, traditional treatment strategies and emerging nanomedicines, summarize the barriers and methods for transporting nanomedicine to the lesions, and illustrate the latest progress of nanomedicine in treating ischemic stroke, with a view to providing a new feasible path for the treatment of cerebral ischemia.

Intranasal temperature-sensitive hydrogels of cannabidiol inclusion complex for the treatment of post-traumatic stress disorder

Post-traumatic stress disorder (PTSD) is a psychiatric disease that seriously affects brain function. Currently, selective serotonin reuptake inhibitors (SSRIs) are used to treat PTSD clinically but have decreased efficiency and increased side effects. In this study, nasal cannabidiol inclusion complex temperature-sensitive hydrogels (CBD TSGs) were prepared and evaluated to treat PTSD. Mice model of PTSD was established with conditional fear box. CBD TSGs could significantly improve the spontaneous behavior, exploratory spirit and alleviate tension in open field box, relieve anxiety and tension in elevated plus maze, and reduce the freezing time. Hematoxylin and eosin and c-FOS immunohistochemistry slides showed that the main injured brain areas in PTSD were the prefrontal cortex, amygdala, and hippocampus CA1. CBD TSGs could reduce the level of tumor necrosis factor-α caused by PTSD. Western blot analysis showed that CBD TSGs increased the expression of the 5-HT1A receptor. Intranasal administration of CBD TSGs was more efficient and had more obvious brain targeting effects than oral administration, as evidenced by the pharmacokinetics and brain tissue distribution of CBD TSGs. Overall, nasal CBD TSGs are safe and effective and have controlled release. There are a novel promising option for the clinical treatment of PTSD.

Escape from abluminal LRP1-mediated clearance for boosted nanoparticle brain delivery and brain metastasis treatment

Breast cancer brain metastases (BCBMs) are one of the most difficult malignancies to treat due to the intracranial location and multifocal growth. Chemotherapy and molecular targeted therapy are extremely ineffective for BCBMs due to the inept brain accumulation because of the formidable blood‒brain barrier (BBB). Accumulation studies prove that low density lipoprotein receptor-related protein 1 (LRP1) is promising target for BBB transcytosis. However, as the primary clearance receptor for amyloid beta and tissue plasminogen activator, LRP1 at abluminal side of BBB can clear LRP1-targeting therapeutics. Matrix metalloproteinase-1 (MMP1) is highly enriched in metastatic niche to promote growth of BCBMs. Herein, it is reported that nanoparticles (NPs-K-s-A) tethered with MMP1-sensitive fusion peptide containing HER2-targeting K and LRP1-targeting angiopep-2 (A), can surmount the BBB and escape LRP1-mediated clearance in metastatic niche. NPs-K-s-A revealed infinitely superior brain accumulation to angiopep-2-decorated NPs-A in BCBMs bearing mice, while comparable brain accumulation in normal mice. The delivered doxorubicin and lapatinib synergistically inhibit BCBMs growth and prolongs survival of mice bearing BCBMs. Due to the efficient BBB penetration, special and remarkable clearance escape, and facilitated therapeutic outcome, the fusion peptide-based drug delivery strategy may serve as a potential approach for clinical management of BCBMs.