The blood-brain barrier in health and chronic neurodegenerative disorders. Neuron. 2008;57:178-201. [PMID: 18215617 DOI: 10.1016/j.neuron.2008.01.003]

Beyond wrecking a wall: revisiting the concept of blood-brain barrier breakdown in ischemic stroke

The blood-brain barrier constitutes a dynamic and interactive boundary separating the central nervous system and the peripheral circulation. It tightly modulates the ion transport and nutrient influx, while restricting the entry of harmful factors, and selectively limiting the migration of immune cells, thereby maintaining brain homeostasis. Despite the well-established association between blood-brain barrier disruption and most neurodegenerative/neuroinflammatory diseases, much remains unknown about the factors influencing its physiology and the mechanisms underlying its breakdown. Moreover, the role of blood-brain barrier breakdown in the translational failure underlying therapies for brain disorders is just starting to be understood. This review aims to revisit this concept of "blood-brain barrier breakdown," delving into the most controversial aspects, prevalent challenges, and knowledge gaps concerning the lack of blood-brain barrier integrity. By moving beyond the oversimplistic dichotomy of an "open"/"bad" or a "closed"/"good" barrier, our objective is to provide a more comprehensive insight into blood-brain barrier dynamics, to identify novel targets and/or therapeutic approaches aimed at mitigating blood-brain barrier dysfunction. Furthermore, in this review, we advocate for considering the diverse time- and location-dependent alterations in the blood-brain barrier, which go beyond tight-junction disruption or brain endothelial cell breakdown, illustrated through the dynamics of ischemic stroke as a case study. Through this exploration, we seek to underscore the complexity of blood-brain barrier dysfunction and its implications for the pathogenesis and therapy of brain diseases.

Alterations in the Blood-Brain Barrier in Mood Disorders and Neurodegenerative Diseases

Depressive disorders and suicidal behaviors represent major causes of health loss. Modifications of brain microvasculature, and specifically alterations of the blood-brain barrier have been supposed to participate in the vulnerability to those disorders along with cognitive impairment, especially in the older adults. In this article, we addressed evidence linking blood-brain barrier impairments with mood disorders and suicide. Secondly, we investigated their relationship with depression in old age, and with neurodegenerative processes. Particular attention was drawn toward the potential interactions between the coagulation processes and the blood-brain barrier dysfunctions, as innovative treatment strategies may emerge from research in those fields. Overall, the studies reviewed highlight the implication of multiple dysfunctions of the blood-brain barrier in mood disorders and suicide. Impairments of the blood-brain barrier show relationships with altered expression of endothelial cell junction proteins. These modifications also implicate receptors of the extracellular matrix, the vascular endothelial growth factor, changes in perivascular astrocytes, and has links with local and systemic inflammatory processes. Dysfunctions of the blood-brain barrier underly chronic stress and participate in psychiatric diathesis in old age. In addition, we outline that coagulation processes are likely to interact with the blood-brain barrier and further contribute to neurodegenerative disorders. In conclusion, new pathophysiological models offer perspectives toward detecting new biomarkers in mood disorders and suicide. In parallel, these models open avenues for developing innovative therapeutic agents, although further considering their potential risks and eventual benefits is needed.

Brain remodeling in stroke patients: A comprehensive review of mechanistic and neuroimaging studies

Stroke-induced brain remodeling involves a complex interplay of neurovascular components, including endothelial cells, microglia, astrocytes, and pericytes, which collectively contribute to the restoration of brain function. These processes are crucial for repairing the blood-brain barrier, regulating inflammation, and promoting neurogenesis. This review examines the mechanisms underlying brain remodeling and the role of advanced neuroimaging techniques-such as functional MRI (fMRI), positron emission tomography (PET), functional near-infrared spectroscopy (fNIRS), and functional ultrasound (fUS)-in assessing these changes. We also discuss various therapeutic approaches aimed at enhancing brain remodeling, including pharmacological agents, stem cell therapy, and rehabilitation strategies that target neurovascular repair and functional recovery. Despite significant progress, challenges remain in translating imaging insights into effective treatments. Future research should focus on integrating multiple imaging modalities to provide a comprehensive view of neurovascular changes and refining therapeutic interventions to optimize recovery and functional outcomes in stroke patients.

Acute high-fat high-sugar diet rapidly increases blood-brain barrier permeability in mice

The blood-brain barrier (BBB) maintains brain homeostasis by protecting the brain from pathological stimuli and controlling the entry of physiological substances from the periphery. Consequently, alterations in BBB permeability may pose a threat to brain health. Long-term consumption of a high-fat high-sugar/Western diet (HFD) is known to induce BBB dysfunction. However, nothing is known about the immediate effects of acute HFD consumption on the BBB. Using spectrophotometry and in vivo 2-photon microscopy in mice, we demonstrate region-specific BBB leakage already after 1 h of HFD for low- and high-molecular-weight tracers. Acute HFD also significantly increased BBB permeability to the anticancer drug doxorubicin. These previously unknown effects of acute HFD in mice may have far-reaching implications for the clinical use of drugs depending on the dietary habits of the patient, and might inform future studies on drug transport to the brain.

The Blood-Brain Barrier: Composition, Properties, and Roles in Brain Health

Blood vessels are critical to deliver oxygen and nutrients to tissues and organs throughout the body. The blood vessels that vascularize the central nervous system (CNS) possess unique properties, termed the blood-brain barrier (BBB), which allow these vessels to tightly regulate the movement of ions, molecules, and cells between the blood and the brain. This precise control of CNS homeostasis allows for proper neuronal function and protects the neural tissue from toxins and pathogens, and alterations of this barrier are important components of the pathogenesis and progression of various neurological diseases. The physiological barrier is coordinated by a series of physical, transport, and metabolic properties possessed by the brain endothelial cells (ECs) that form the walls of the blood vessels. These properties are regulated by interactions between different vascular, perivascular, immune, and neural cells. Understanding how these cell populations interact to regulate barrier properties is essential for understanding how the brain functions in both health and disease contexts.

Neuroinflammation in Alzheimer disease

Increasing evidence points to a pivotal role of immune processes in the pathogenesis of Alzheimer disease, which is the most prevalent neurodegenerative and dementia-causing disease of our time. Multiple lines of information provided by experimental, epidemiological, neuropathological and genetic studies suggest a pathological role for innate and adaptive immune activation in this disease. Here, we review the cell types and pathological mechanisms involved in disease development as well as the influence of genetics and lifestyle factors. Given the decade-long preclinical stage of Alzheimer disease, these mechanisms and their interactions are driving forces behind the spread and progression of the disease. The identification of treatment opportunities will require a precise understanding of the cells and mechanisms involved as well as a clear definition of their temporal and topographical nature. We will also discuss new therapeutic strategies for targeting neuroinflammation, which are now entering the clinic and showing promise for patients.

IL-8 and IL-1β in the Cerebrospinal Fluid of Patient With Creutzfeldt-Jakob Disease: A Case Report

Inflammatory cytokines play a crucial role in Creutzfeldt-jakob disease (CJD). We examined inflammatory cytokine levels in both blood and CSF in a CJD patient and an epileptic encephalopathy as a control case. Results showed that IL-6, IL-8, IL-1β, and TNF-α levels were elevated in blood, but only IL-8 and IL-1β levels, especially IL-8, were significantly elevated in Cerebrospinal fluid (CSF). This suggests that IL-8 and IL-1β are closely related to cognitive impairment and blood-brain barrier (BBB) damage in CJD, and IL-8 might be a key target in early cognitive impairment in CJD.

Nanoparticles Designed Based on the Blood-Brain Barrier for the Treatment of Cerebral Ischemia-Reperfusion Injury

Cerebral ischemia-reperfusion injury (CI/RI) is currently considered a significant factor affecting the prognosis of ischemic stroke. The blood-brain barrier (BBB) plays multiple roles in the treatment ofCI/RI. BBB leakage allows bloodborne toxins to exacerbate the stroke pathology. Yet as the physiological barrier that separates the blood from the brain, BBB also poses a significant obstacle to therapeutic drug delivery. Therefore, it is essential to consider both crossing and repairing the BBB in the process of the treatment of CI/RI. Leveraging the exceptional benefits of nanoparticles (NPs) for BBB penetration and targeted repair, numerous NPs are developed as promising drug delivery platforms. Considering the complex role of the BBB in CI/RI, this review delves into the strategies for designing NPs to cross the BBB, focusing on peptide-modified NPs, cell-mediated NPs, cell membrane-derived NPs, and BBB-modulating NPs. Additionally, it summarizes design strategies of NPs targeting endothelial cells (ECs), astrocytes, and those aimed at regulating the microenvironment to repair the BBB. On this basis, it reveals the prospects and challenges of NPs designed around the BBB in CI/RI treatment. And it highlights the need to combine BBB permeability promotion and BBB repair in nanoparticle strategies designed based on the BBB to achieve more effective treatment.

Molecular imaging-guided diagnosis and treatment integration for brain diseases

In practical clinical scenarios, improved diagnostic methods have been developed for the precise visualization of molecular targets using molecular imaging in brain diseases. Recently, the introduction of innovative molecular imaging modalities across both macroscopic and mesoscopic dimensions, with remarkable specificity and spatial resolution, has expanded the scope of applications beyond diagnostic testing, with the potential to guide therapeutic interventions, offering real-time feedback in the context of brain therapy. The molecular imaging-guided integration of diagnosis and treatment holds the potential to revolutionize disease management by enabling the real-time monitoring of treatment responses and therapy adjustments. Given the vibrant and ever-evolving nature of this field, this review provides an integrated picture on molecular image-guided diagnosis and treatment integration for brain diseases involving the basic concepts, significant breakthroughs, and recent trends. In addition, based on the current achievements, some critical challenges are also discussed.

Predictive value of circulating inflammatory biomarkers for early-onset post-stroke cognitive impairment: a prospective cohort study

Introduction

Stroke ranks as the second leading cause of mortality and the third leading cause of disability globally. Post-stroke cognitive impairment (PSCI) is a prevalent complication following acute ischemic stroke, imposing substantial burdens on patients, families, and society. This study aimed to explore the potential of circulating immune-inflammatory markers as predictors of PSCI.

Methods

Conducted as a prospective observational cohort study from June 2023 to August 2024 at the Affiliated Drum Tower Hospital, Medical School of Nanjing University, it included patients experiencing their first acute ischemic stroke within 72 h of symptom onset. Cognitive assessments were conducted 7 to 10 days post-stroke using the Montreal Cognitive Assessment (MoCA), with scores below 23 indicating PSCI.

Results

A total of 146 patients meeting the inclusion criteria were recruited, with 71 patients exhibiting PSCI during the acute phase of stroke. Compared to patients in the post-stroke no cognitive impairment (PSNCI) group, those with PSCI demonstrated significantly elevated peripheral blood neutrophil-to-lymphocyte ratio (NLR), globulin-to-lymphocyte ratio (GLR), and C-reactive protein-to-lymphocyte ratio (CLR), while the lymphocyte-to-monocyte ratio (LMR) was notably reduced (all p < 0.05). Both univariate and multivariate logistic regression analyses identified GLR as independently associated with PSCI. After adjusting for common clinical variables, the odds ratio (OR) for the highest tertile of GLR compared to the lowest was 6.20 (95% CI, 2.10-18.33; p = 0.001). The optimal GLR cutoff was 18.22, with a sensitivity of 62.0%, specificity of 78.7%, and an area under curve (AUC) of 0.726.

Conclusion

This study indicates that elevated circulating GLR levels during the acute phase post-stroke onset are an independent risk factor for early-onset PSCI, even after adjusting for clinically relevant variables.

Multidimensional exploration of hydrogels as biological scaffolds for spinal cord regeneration: mechanisms and future perspectives

Spinal cord injury (SCI) is a severe condition that frequently leads to permanent disabilities and neurological dysfunction. Its progression is driven by a multifaceted pathophysiology, encompassing direct trauma, secondary injury cascades, and intricate cellular and molecular responses. While current therapies focus on alleviating symptoms and restoring functionality, achieving effective neural regeneration in the spinal cord continues to be a significant challenge. Hydrogels, recognized for their exceptional biocompatibility, conductivity, and injectability, have shown great potential as advanced scaffolds to support neuronal and axonal regeneration. Recently, these materials have attracted significant interest in the field of SCI rehabilitation research. This review concludes recent progress in hydrogel-based strategies for SCI rehabilitation, emphasizing their distinct properties, underlying mechanisms, and integration with bioactive molecules, stem cells, and complementary biomaterials. Hydrogels foster neuronal regeneration by providing a tailored microenvironment, while advanced features such as self-repair, electrical conductivity, and controlled drug release significantly enhance their therapeutic potential in experimental models. This review explores hydrogel technologies and their applications, underscoring their potential to address the challenges of SCI treatment and paving the way for future clinical implementation.

A Biomimetic Human Multi-Cellular In Vitro Model of the Blood-Brain Barrier

Current in vitro models fail to recapitulate specific physiological properties of the human blood-brain barrier (BBB); hence the need for a reliable platform to study central nervous system diseases and drug permeability. To mimic the normally tight blood-brain interface, primary human endothelial cells (HAECs) and primary human astrocytes (A) were grown in a confined space of the physical scaffold created by gelatin methacrylate (GelMA) hydrogel to allow optimal astrocyte-endothelial cell direct/indirect interaction. Evidence for a physiologically relevant BBB was established by assessing the expression of tight junction markers conferring the barrier function, and by measuring biophysical attributes using the trans-endothelial electrical resistance (TEER) and the Evans blue albumin (EBA) permeability assay. An HAEC+A three-dimensional (3D) co-culture was associated with 12-fold higher claudin-5 (CLDN5) and cadherin-1 (CDH1 or Epithelial [E]-cadherin) transcriptional levels than two-dimensional (2D) models. This model conferred the highest TEER (45 Ω·cm2) in 3D HAEC+A, which value was 30 Ω·cm2 in 2D (p < 0.01) and 25 Ω·cm2 in 3D HAEC cultures (p < 0.001). Functionally, in 3D HAEC+A co-cultures, higher TEER resulted in 10-fold and 7-fold lower EBA permeability at 120 min, in HAECs alone or in to 2D co-cultures (p < 0.01). The established human primary cell model has acquired features mimicking the human BBB in vitro, and is now poised to be tested for the permeability of the BBB to pharmacological agents, parasites, cells (such as brain-tropic cancer cell metastasis) and any mechanisms that might involve traversing the BBB.

Engineered nanoparticles for the treatment of Alzheimer's disease

Alzheimer's disease (AD) is one of the most common diseases characterized by neurodegeneration and is becoming a major public health problem worldwide. AD is manifested mainly by progressive impairments in cognition, emotion, language and memory in the elderly population. Many treatment strategies have been explored for decades; however, there is still no effective way to address the root cause of AD pathogenesis, only to target symptoms to improve patient cognitive outcomes. Intracerebral administration is difficult because of the challenges posed by the blood‒brain barrier (BBB). NPs are materials with sizes between 1 and 100 nm that can improve biocompatibility, extend the half-life, transport macromolecules, be delivered across the BBB to the central nervous system, and exhibit good targeting capabilities. NPs can provide new ideas for the treatment of AD in terms of their antiaging, antineuroinflammatory, antioxidative, and nerve repair-promoting effects. In this manuscript, we first describe the relationship between AD and the BBB. Second, we introduce the application of nanoparticles for AD treatment. Finally, we summarize the challenges faced by nanoparticles in the treatment of AD.

Small Extracellular Vesicles From Hypoxia-Neuron Maintain Blood-Brain Barrier Integrity

BACKGROUND

Acute ischemic stroke disrupts communication between neurons and blood vessels in penumbral areas. How neurons and blood vessels cooperate to achieve blood-brain barrier repair remains unclear. Here, we reveal crosstalk between ischemic penumbral neurons and endothelial cells (ECs) mediated by circular RNA originating from oxoglutarate dehydrogenase (CircOGDH).

METHODS

We analyzed clinical data from patients with acute ischemic stroke to explore the relationship between CircOGDH levels and hemorrhagic transformation events. In addition, a middle cerebral artery occlusion and reperfusion mouse model with neuronal CircOGDH suppression was used to assess endothelial permeability. ECs with increased CircOGDH expression were analyzed for changes in COL4A4 (collagen type IV alpha 4) levels, and in vitro coculture experiments were conducted to examine small extracellular vesicle-mediated CircOGDH transfer between neurons and ECs.

RESULTS

Clinical data indicated that reduced CircOGDH levels were correlated with increased hemorrhagic transformation in patients with acute ischemic stroke. In the middle cerebral artery occlusion and reperfusion model, neuronal CircOGDH suppression impaired the restoration of endothelial permeability. ECs with increased CircOGDH expression exhibited higher COL4A4 levels, which helped maintain vascular stability. In vitro, hypoxic neurons transferred CircOGDH to ECs via small extracellular vesicles, leading to elevated COL4A4 expression and enhanced endothelial integrity.

CONCLUSIONS

Our findings highlight the significance of CircOGDH in neuron-EC crosstalk via small extracellular vesicles in the ischemic penumbra, emphasizing the need for balanced intervention strategies in acute ischemic stroke management.

Exploring neuropharmacokinetics: mechanisms, models, and clinical implications

Neuropharmacokinetics is an emerging field dedicated to understanding the pharmacokinetics of drugs within the central nervous system (CNS), with a particular emphasis on overcoming the challenges posed by the blood-brain barrier. This paper reviews the latest advancements in drug delivery strategies, including nanoparticle-based systems, receptor-mediated transcytosis, and efflux transporter inhibition, which have been designed to enhance drug penetration into the brain. Additionally, the use of advanced imaging techniques such as positron emission tomography, functional magnetic resonance imaging, and magnetic resonance imaging with contrast agents has provided critical insights into drug distribution, receptor occupancy, and the functional impact of therapeutic agents within the CNS. These innovations not only enhance our understanding of CNS drug action but also pave the way for more effective treatments for neurological and psychiatric disorders.

Alpha‑Asarone Ameliorates Neuronal Injury After Ischemic Stroke and Hemorrhagic Transformation by Attenuating Blood-Brain Barrier Destruction, Promoting Neurogenesis, and Inhibiting Neuroinflammation

Recombinant tissue-type plasminogen activator (rt-PA), the primary drug for acute ischemic stroke (IS), has a narrow therapeutic window and carries a potential risk of hemorrhagic transformation (HT). Without rt-PA administration, patients may suffer permanent cerebral ischemia. Alpha-asarone (ASA), a natural compound derived from Acorus tatarinowii Schott, exhibits diverse neuropharmacological effects. This study aims to investigate whether ASA could improve outcomes in IS and be used to mitigate HT induced by rt-PA. We employed models of permanent middle cerebral artery occlusion (pMCAO) and photothrombotic cortical injury (PCI) to investigate both the therapeutic efficacy and underlying mechanisms of ASA during the acute and recovery periods following IS, respectively. Additionally, Sprague-Dawley rats were subjected to rt-PA treatment at 6-h post-PCI to mimic HT (rt-PA-HT). Our results revealed three key findings: (1) ASA demonstrated therapeutic effects in the acute phase of pMCAO rats by alleviating blood-brain barrier damage through inhibition of glial cell-mediated neuroinflammation; (2) administration of ASA 24 h after stroke ameliorated the neurological damage during the recovery phase in PCI mice by promoting neurogenesis via activation of the BDNF/ERK/CREB signaling pathway; (3) ASA attenuated rt-PA-HT injury by modulating the NLRP3/Caspase1/IL-1β and IL-18 pathways. Overall, our findings suggest that ASA mitigates neuronal injury following IS and HT, positioning it as a promising candidate for treating these conditions.

Down-regulation of platelet-derived growth factor receptor β in pericytes increases blood-brain barrier permeability and significantly enhances α-synuclein in a Parkinson's Disease 3D cell model in vitro under hyperglycemic condition

BACKGROUND

Parkinson's Disease (PD) often presents with a compromised blood-brain barrier (BBB), which hyperglycemia may exacerbate. Pericytes, a key cell for BBB integrity, are potential therapeutic targets for neurodegenerative disorders. Few studies have developed 3D PD cell models incorporating neurovascular units (NVU) through the co-culture of human endothelial, pericytes, astrocytes, and SH-SY5Y cells to evaluate BBB impairment and the role of pericytes under hyperglycemic condition.

METHOD

A 3D PD like cell model was developed using 6-OHDA-affected SH-SY5Y cells, combined with endothelial cells, pericytes, and astrocytes through the Real Architecture for Tissue (RAFT) 3D co-culture system. PD incorporating reduced (30 % and 89 %) PDGFRβ NVU (RPN) with or without hyperglycemic model (HM) were also established. BBB permeability to sodium fluorescein was assessed, and BBB impairment was evaluated using BBB-associated proteins (ZO-1, CD54, CD144), cell-specific proteins (CD31, GFAP, PDGFRβ, CD13), tyrosine hydroxylase (TH), α-synuclein, oligomeric α-synuclein, and α-synuclein (ser9).

RESULTS

PD 3D cell models incorporating RPN with or without hyperglycemia were successfully established in vitro. Graduately increased BBB impairment was observed in PD, PD with RPN, and PD with RPN combined with HM, indicated by decreased BBB-associated and cell-specific proteins, reduced TH, and increased α-synuclein, oligomeric α-synuclein, and α-synuclein (ser9) compared to the NVU model.

CONCLUSION

Reduced pericyte PDGFRβ could increase BBB permeability, accelerate PD progression, and exacerbate under hyperglycemic condition.

Endothelial Neurogranin Regulates Blood-Brain Barrier Permeability via Modulation of the AKT Pathway

Neurogranin (Ng) expression is a biomarker for Alzheimer's disease. A loss of brain Ng and an increase in CSF Ng positively correlate with cognitive decline. Ng is known to regulate neuronal calcium-calmodulin binding and synaptic plasticity, which are critical for learning/memory. Interestingly, we discovered that Ng is also expressed in mouse and human blood-brain barrier (BBB). However, the role of Ng expression in brain vasculature remains largely undefined. In this study, we investigated the role of Ng expression on neurovascular structure and function using Ng null mice and human cerebral microvascular endothelial (hCMEC/D3) cells. We performed brain clearing and immunolabeling of blood vessels from whole brains and brain slices. Deletion of Ng significantly decreases neurovascular density in mice. Using in vivo permeability assays, we found increased neurovascular permeability in Ng null mice. We also observed significant changes in the expression of tight junction proteins using western blot and immunofluorescent staining. To identify the molecular pathways involved, we carried out label-free proteomics on brain lysates from endothelial-specific Ng knockout mice. Ingenuity Pathway Analysis indicated that the AKT pathway is attenuated in the vasculature of endothelial-specific Ng knockout mice. To validate these in vivo findings, we pharmacologically manipulated AKT signaling in hCMEC/D3 cells and observed that inhibition of AKT activation causes increased permeability. Our results indicate that the loss of Ng expression alters neurovascular structure and permeability, potentially contributing to neurological dysfunction. Therefore, modulating Ng expression in the BBB may offer a novel therapeutic approach for Alzheimer's disease.

Meta-analysis of the make-up and properties of in vitro models of the healthy and diseased blood-brain barrier

In vitro models of the human blood-brain barrier (BBB) are increasingly used to develop therapeutics that can cross the BBB for treating diseases of the central nervous system. Here we report a meta-analysis of the make-up and properties of transwell and microfluidic models of the healthy BBB and of BBBs in glioblastoma, Alzheimer's disease, Parkinson's disease and inflammatory diseases. We found that the type of model, the culture method (static or dynamic), the cell types and cell ratios, and the biomaterials employed as extracellular matrix are all crucial to recapitulate the low permeability and high expression of tight-junction proteins of the BBB, and to obtain high trans-endothelial electrical resistance. Specifically, for models of the healthy BBB, the inclusion of endothelial cells and pericytes as well as physiological shear stresses (~10-20 dyne cm-2) are necessary, and when astrocytes are added, astrocytes or pericytes should outnumber endothelial cells. We expect this meta-analysis to facilitate the design of increasingly physiological models of the BBB.

NIR-II Fluorescent Protein Created by In Situ Albumin-Tagging for Sensitive and Specific Imaging of Blood-Brain Barrier Disruption

Imaging albumin in vivo is a reliable strategy to visualize blood-brain barrier (BBB) disruption by detecting the dye-labeled albumin leaking into brain parenchyma. Although Evans Blue (EB) and indocyanine green (ICG) dyes have been applied to assess BBB impairment, their naked-eye observation or near-infrared-I (NIR-I) imaging window limit the imaging sensitivity and contrast for this promising "albumin-based" strategy. Herein, an albumin-specific tagged near-infrared-II (NIR-II) probe is engineered as a chromophore to construct fluorescent proteins (FPs) in situ for assessing BBB disruption in stroke. The optimized chromophore, C7-1080, can covalently bind to albumin through nucleophilic substitution, forming FPs without adjuvant. Notably, the albumin effectively acts as a brightness enhancer and stability regulator for chromophores through the tight clamping effect. Theoretical simulation, proteomics, and protein mutation techniques are employed to investigate the binding behavior between albumin and chromophore. The in situ NIR-II FPs construction strategy facilitates high-precision dual-channel imaging of BBB disruption and cerebral vessels during ischemic stroke when combined with the IR-808Ac probe. Overall, the in situ albumin-specific tag holds promise for diagnosing and monitoring strokes, presenting a tool for investigating the progression and therapeutic responses of related diseases.

p23 protects against ferroptosis of brain microvascular endothelial cells in ischemic stroke

Ferroptosis is a type of iron‑dependent regulated cell death that differs from apoptosis, autophagy or necrosis. p23 serves as a co‑chaperone and performs a unique biological function in various diseases by binding to client proteins to modulate their biological functions; however, its effect on ferroptosis remains largely unknown. In the present study, the effects of cerebral ischemia/reperfusion (I/R) injury (CIRI) or oxygen‑glucose deprivation/reoxygenation on the blood‑brain barrier (BBB) and ferroptosis in brain microvascular endothelial cells (BMECs), as well as the expression of p23, were examined. Subsequently, the effects of p23 on CIRI‑induced BBB dysfunction and BMEC ferroptosis were determined. Finally, the role of glutathione peroxidase 4 (GPX4) in the regulatory effects of p23 on ferroptosis was detected. The results revealed that p23 protected against BBB injury caused by CIRI by inhibiting ferroptosis in BMECs. The effect of p23 on ferroptosis was then explored, and it was found that the expression of GPX4, a major regulator of ferroptosis, was promoted by p23. Furthermore, molecular docking and co‑immunoprecipitation experiments revealed that p23 could bind to GPX4 through its N‑terminal domain (1‑90aa), enhance the stability of GPX4 and inhibit the degradation of GPX4 by cycloheximide. Finally, a cerebral I/R animal model was established using GPX4 conditional knockout mice (GPX4 FosCreERT2/+), and it was revealed that the protective effect of p23 overexpression on the BBB in GPX4 FosCreERT2/+ mice was attenuated compared with that in GPX4 FosCreERT2/‑ mice. In conclusion, p23 may serve a protective role against cerebral I/R‑induced BBB injury by inhibiting ferroptosis in BMECs through enhancing the stability of GPX4, providing a potential therapeutic target for ischemic stroke.

Impact of Microglia-Derived Extracellular Vesicles on Resident Central Nervous System Cell Populations After Acute Brain Injury Under Various External Stimuli Conditions

Acute brain injuries (ABI) caused by various emergencies can lead to structural and functional damage to brain tissue. Common causes include traumatic brain injury, cerebral hemorrhage, ischemic stroke, and heat stroke. Globally, ABI represent a significant portion of neurosurgical cases. Previous studies have emphasized the significant therapeutic potential of stem cell-derived extracellular vesicles (EVs). Recent research indicates that EVs extracted from resident cells in the central nervous system (CNS) also show therapeutic potential following brain injury. Microglia, as innate immune cells of the CNS, respond to changes in the internal environment by altering their phenotype and secreting EVs that impact various CNS cells, including neurons, astrocytes, oligodendrocytes, endothelial cells, neural stem cells (NSCs), and microglia themselves. Notably, under different external stimuli, microglia can either promote neuronal survival, angiogenesis, and myelin regeneration while reducing glial scarring and inflammation, or they can exert opposite effects. This review summarizes and evaluates the current research findings on how microglia-derived EVs influence various CNS cells after ABI under different external stimuli. It analyzes the interaction mechanisms between EVs and resident CNS cells and discusses potential future research directions and clinical applications.

Comprehensive characterization of metabolic consumption and production by the human brain

Metabolism is vital for brain function. However, a systematic investigation to understand the metabolic exchange between the human brain and circulatory system has been lacking. Here, we compared metabolomes and lipidomes of blood samples from the cerebral venous sinus and femoral artery to profile the brain's uptake and release of metabolites and lipids (1,365 metabolites and 140 lipids). We observed a high net uptake of glucose, taurine, and hypoxanthine and identified glutamine and pyruvate as significantly released metabolites by the brain. Triacylglycerols are the most prominent class of lipid consumed by the brain. The brain with cerebral venous sinus stenosis (CVSS) consumed more glucose and lactate and released more glucose metabolism byproducts than the brain with cerebral venous sinus thrombosis (CVST). Our data also showed age-related alterations in the uptake and release of metabolites. These results provide a comprehensive view of metabolic consumption and production processes within the human brain.

Dissecting endothelial cell heterogeneity with new tools

The formation of a blood vessel network is crucial for organ development and regeneration. Over the past three decades, the central molecular mechanisms governing blood vessel growth have been extensively studied. Recent evidence indicates that vascular endothelial cells-the specialized cells lining the inner surface of blood vessels-exhibit significant heterogeneity to meet the specific needs of different organs. This review focuses on the current understanding of endothelial cell heterogeneity, which includes both intra-organ and inter-organ heterogeneity. Intra-organ heterogeneity encompasses arterio-venous and tip-stalk endothelial cell specialization, while inter-organ heterogeneity refers to organ-specific transcriptomic profiles and functions. Advances in single-cell RNA sequencing (scRNA-seq) have enabled the identification of new endothelial subpopulations and the comparison of gene expression patterns across different subsets of endothelial cells. Integrating scRNA-seq with other high-throughput sequencing technologies promises to deepen our understanding of endothelial cell heterogeneity at the epigenetic level and in a spatially resolved context. To further explore human endothelial cell heterogeneity, vascular organoids offer powerful tools for studying gene function in three-dimensional culture systems and for investigating endothelial-tissue interactions using human cells. Developing organ-specific vascular organoids presents unique opportunities to unravel inter-organ endothelial cell heterogeneity and its implications for human disease. Emerging technologies, such as scRNA-seq and vascular organoids, are poised to transform our understanding of endothelial cell heterogeneity and pave the way for innovative therapeutic strategies to address human vascular diseases.

Harnessing the Potential of Exosomes in Therapeutic Interventions for Brain Disorders

Exosomes, which are nano-sized natural vesicles secreted by cells, are crucial for intercellular communication and interactions, playing a significant role in various physiological and pathological processes. Their characteristics, such as low toxicity and immunogenicity, high biocompatibility, and remarkable drug delivery capabilities-particularly their capacity to traverse the blood-brain barrier-make exosomes highly promising vehicles for drug administration in the treatment of brain disorders. This review provides a comprehensive overview of exosome biogenesis and isolation techniques, strategies for the drug loading and functionalization of exosomes, and exosome-mediated blood-brain barrier penetration mechanisms, with a particular emphasis on recent advances in exosome-based drug delivery for brain disorders. Finally, we address the opportunities and challenges associated with utilizing exosomes as a drug delivery system for the brain, summarizing the barriers to clinical translation and proposing future research directions.

Aging, vascular dysfunction, and the blood-brain barrier: unveiling the pathophysiology of stroke in older adults

The progressive decline of vascular integrity and blood-brain barrier (BBB) function is associated with aging, a major risk factor for stroke. This review describes the cellular and molecular changes in the brain microvasculature of the neurovascular unit (NVU) that contribute to the development of BBB dysfunction in aging, such as endothelial cell senescence, oxidative stress, and degradation of tight junction proteins. Stroke severity and recovery are exacerbated by BBB breakdown, leading to neuroinflammation, neurotoxicity, and cerebral oedema while identifying molecular mechanisms such as the NLRP3 inflammasome, matrix metalloproteinases (MMPs), and non-coding RNAs (e.g., miRNAs and circRNAs) that drive BBB disruption in aging and stroke. Real-time assessment of BBB permeability in stroke pathophysiology is made possible using advanced imaging techniques, such as dynamic contrast-enhanced MRI and positron emission tomography. Furthermore, biomarkers, including claudin-5, PDGFRβ, or albumin concentration, serve as markers of BBB integrity and vascular health. Restoration of BBB function and stroke recovery with emerging therapeutic strategies, including sirtuin modulators (SIRT1 and SIRT3 activators to enhance endothelial function and mitochondrial health), stem cell-derived extracellular vesicles (iPSC-sEVs for BBB repair and neuroprotection), NLRP3 inflammasome inhibitors (MCC950 to attenuate endothelial pyroptosis and inflammation), hydrogen-rich water therapy (to counteract oxidative stress-induced BBB damage), and neuropeptides such as cortistatin (to regulate neuroinflammation and BBB stability), is promising. This review explores the pathophysiological mechanisms of BBB dysfunction in aging and stroke, their relation to potential therapeutic targets, and novel approaches to improve vascular health and neuroprotection.

Vagus nerve stimulation (VNS) preventing postoperative cognitive dysfunction (POCD): two potential mechanisms in cognitive function

Postoperative cognitive dysfunction (POCD) impacts a significant number of patients annually, frequently impairing their cognitive abilities and resulting in unfavorable clinical outcomes. Aimed at addressing cognitive impairment, vagus nerve stimulation (VNS) is a therapeutic approach, which was used in many mental disordered diseases, through the modulation of vagus nerve activity. In POCD model, the enhancement of cognition function provided by VNS was shown, demonstrating VNS effect on cognition in POCD. In the present study, we primarily concentrates on elucidating the role of the VNS improving the cognitive function in POCD, via two potential mechanisms: the inflammatory microenvironment and epigenetics. This study provided a theoretical support for the feasibility that VNS can be a potential method to enhance cognition function in POCD.

A guide for blood-brain barrier models

Understanding the intricate mechanisms underlying brain-related diseases hinges on unraveling the pivotal role of the blood-brain barrier (BBB), an essential dynamic interface crucial for maintaining brain equilibrium. This review offers a comprehensive analysis of BBB physiology, delving into its cellular and molecular components while exploring a wide range of in vivo and in vitro BBB models. Notably, recent advancements in 3D cell culture techniques are explicitly discussed, as they have significantly improved the fidelity of BBB modeling by enabling the replication of physiologically relevant environments under flow conditions. Special attention is given to the cellular aspects of in vitro BBB models, alongside discussions on advances in stem cell technologies, providing valuable insights into generating robust cellular systems for BBB modeling. The diverse array of cell types used in BBB modeling, depending on their sources, is meticulously examined in this comprehensive review, scrutinizing their respective derivation protocols and implications. By synthesizing diverse approaches, this review sheds light on the improvements of BBB models to capture physiological conditions, aiding in understanding BBB interactions in health and disease conditions to foster clinical developments.

Design, current states, and challenges of nanomaterials in anti-neuroinflammation: A perspective on Alzheimer's disease

Alzheimer's disease (AD), an age-related neurodegenerative disease, brings huge damage to the society, to the whole family and even to the patient himself. However, until now, the etiological factor of AD is still unknown and there is no effective treatment for it. Massive deposition of amyloid-beta peptide(Aβ) and hyperphosphorylation of Tau proteins are acknowledged pathological features of AD. Recent studies have revealed that neuroinflammation plays a pivotal role in the pathology of AD. With the rise of nanomaterials in the biomedical field, researchers are exploring how the unique properties of these materials can be leveraged to develop effective treatments for AD. This article has summarized the influence of neuroinflammation in AD, the design of nanoplatforms, and the current research status and inadequacy of nanomaterials in improving neuroinflammation in AD.

Beta-caryophyllene inhibits the permeability of the blood-brain barrier in MPTP-induced parkinsonism

INTRODUCTION

Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder worldwide. Although the precise pathogenesis of PD remains unclear, several studies demonstrate that oxidative stress, inflammation, low levels of antioxidants, and the presence of biomolecules that generate reactive oxygen species can disrupt the blood-brain barrier (BBB) as an essential feature of the disease.

AIMS

This study aimed to test whether agonism to cannabinoid receptor type 2 (CB2) through the administration of β-caryophyllene (BCP) could correct BBB permeability in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) parkinsonism induction model.

METHODS

We conducted a molecular assessment of proteins (immunochemistry and western blot), BBB permeability, and related biomarkers of PD (lipid peroxidation) in the MPTP mouse model of the disease.

RESULTS

Expression of zonula occludens (ZO-1) and occludin tight junction (TJ) proteins was dampened in the striatum and substantia nigra pars compacta of mice, while lipid peroxidation and BBB permeability increased in the striatum in the MPTP-treated group, and these effects were reversed under BCP administration. This phytocannabinoid was able to restore protein expression and immunoreactivity of tyrosine hydroxylase (TH), ionized calcium-binding adapter molecule 1 (Iba-1), and glial fibrillary acidic protein (GFAP), as well as nuclear factor-erythroid 2-related factor (NRF2) translocation to the nucleus, and NADPH quinone oxidase 1 (NQO1) expression in mice treated with MPTP.

CONCLUSION

These results highlight the role of CB2 as a therapeutic target for PD, suggesting that its activation may ameliorate PD-related BBB disruption and oxidative stress, reducing the selective death of dopaminergic neurons.

Fibrinogen degradation products exacerbate alpha-synuclein aggregation by inhibiting autophagy via downregulation of Beclin1 in multiple system atrophy

Multiple system atrophy (MSA) is a rapidly progressive neurodegenerative disease arising from accumulation of the α-synuclein and aberrant protein clearance in oligodendrocytes. The mechanisms of autophagy involved in the progression of MSA remain poorly understood. It is reported that MSA patients have blood-brain barrier impairments, which may increase the entry of fibrinogen into the brain. However, the roles of fibrinogen and its degradation products (FDPs) on autophagy and α-synuclein accumulation in MSA remain unknown. Here, we established the MSA animal model by intraperitoneal injection of 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine (MPTP) and 3-nitropropionic acid (3-NP), and cellular models by adding fibrillar α-syn into oligodendrocytes to investigate the mechanisms of FDPs on autophagy and accumulation of α-synuclein in oligodendrocytes. We found that FDPs inhibit the entry of α-synuclein into lysosomes for degradation, increasing aggregation of α-synuclein in oligodendrocytes (OLN-93). Our findings indicated that in OLN-93, FDPs inhibited the expressions of Beclin1 and Bif-1, which could promote the fusion of autophagosomes with lysosomes. Furthermore, the expression of α-synuclein was elevated in FDPs-injected mice, accompanied by an increase in the protein level of p62. We detected elevated expression of FDPs in the striatum of MSA mice. Finally, FDPs inhibited the expression of Beclin1 and Bif-1, which led to aberrant autophagic degradation and increased aggregation of α-synuclein and phospho-α-synuclein in MSA mice. Our study illustrates that FDPs can cause aggregation of α-synuclein in MSA by inhibiting Beclin1-mediated autophagy, which may exacerbate disease progression. These results provide a new therapeutic approach for MSA, that targets the inhibitory effect of FDPs on oligodendrocyte autophagy.

From blood vessels to brain cells: Connecting the circulatory system and Parkinson's disease

Parkinson's disease (PD) is traditionally recognized as a neurodegenerative disorder characterized by motor dysfunction and α-synuclein protein accumulation in the brain. However, recent research suggests that the circulatory system may also contribute to PD pathogenesis through the spread of α-synuclein beyond the brain. The blood-brain barrier (BBB), a key regulator of molecular exchange between the bloodstream and the brain, may become compromised in PD, allowing harmful substances, including pathogenic forms of α-synuclein, to infiltrate the brain and promote neurodegeneration. Transport mechanisms such as P-glycoprotein and the low-density lipoprotein (LDL) receptor-related protein (LRP-1) further modulate the movement of α-synuclein across the BBB, influencing disease progression. Additionally, extracellular vesicles are emerging as crucial mediators in the dissemination of α-synuclein between the brain and peripheral tissues, facilitating its spread and accumulation. The lymphatic system, responsible for clearing α-synuclein, may also contribute to PD pathology when impaired. This review highlights the growing evidence for a circulatory axis in the initiation and progression of PD. We propose that future research should explore the hypothesis that the circulatory system contributes to the pathogenesis of PD by aiding the distribution of α-synuclein throughout the body.

Mechanistic role of proteins and peptides in Management of Neurodegenerative Disorders

Proteins and peptides have emerged as significant contributors in the management of neurodegenerative disorders due to their diverse biological functions. These biomolecules influence various cellular processes, including cellular repair, inflammation reduction, and neuronal survival, which are crucial for mitigating the effects of diseases such as Alzheimer's, Parkinson's, and Amyotrophic Lateral Sclerosis (ALS). By interacting with specific cellular receptors, proteins and peptides like neurotrophic factors, cytokines, and enzyme inhibitors promote neurogenesis, reduce oxidative stress, and enhance synaptic plasticity. Nevertheless, till certain limitations and challenges do exist to deliver these fragile therapeutic bioactives. Moreover, targeted delivery systems, such as nanoparticles and biomolecular carriers, are being developed to improve the bioavailability and specificity of these protein-based therapeutics, ensuring efficient crossing of the blood-brain barrier. This review explores the mechanistic pathways through which these biomolecules act, emphasizing their potential to modify disease progression and improve the quality of life in patients with neurodegenerative conditions. Overall, proteins and peptides are not only seen as promising therapeutic agents but also as foundational tools in advancing personalized medicine in the field of neurodegenerative disorders.

Glutamatergic argonaute2 promotes the formation of the neurovascular unit in mice

Proper formation of the complex neurovascular unit (NVU) along with the blood-brain barrier is critical for building and sustaining a healthy, functioning central nervous system. The RNA binding protein argonaute2 (Ago2) mediates microRNA (miRNA)-mediated gene silencing, which is critical for many facets of brain development, including NVU development. Here, we found that Ago2 in glutamatergic neurons was critical for NVU formation in the developing cortices of mice. Glutamatergic neuron-specific loss of Ago2 diminished synaptic formation, neuronal-to-endothelial cell contacts, and morphogenesis of the brain vasculature, ultimately compromising the integrity of the blood-brain barrier. Ago2 facilitated miRNA targeting of phosphatase and tensin homolog (Pten) mRNA, which encodes a phosphatase that modulates reelin-dependent phosphatidylinositol 3-kinase (PI3K)-Akt signaling within the glutamatergic subpopulation. Conditionally deleting Pten in Ago2-deficient neurons restored Akt2 phosphorylation as well as postnatal development and survival. Several mutations in AGO2 impair small RNA silencing and are associated with Lessel-Kreienkamp syndrome, a neurodevelopmental disorder. When expressed in a neuronal cell line, these human AGO2 loss-of-function variants failed to suppress PTEN, resulting in attenuated PI3K-Akt signaling, further indicating that dysregulation of Ago2 function may contribute to both impaired development and neurological disorders. Together, these results identify Ago2 as central to the engagement of neurons with blood vessels in the developing brain.

Altered cognitive function in obese patients: relationship to gut flora

Obesity is a risk factor for non-communicable diseases such as cardiovascular disease and diabetes, which are leading causes of death and disability. Today, China has the largest number of overweight and obese people, imposing a heavy burden on China's healthcare system. Obesity adversely affects the central nervous system (CNS), especially cognitive functions such as executive power, working memory, learning, and so on. The gradual increase in adult obesity rates has been accompanied by a increase in childhood obesity rates. In the past two decades, the obesity rate among children under 5 years of age has increased from 32 to 42 million. If childhood obesity is not intervened in the early years, it will continue into adulthood and remain there for life. Among the potential causative factors, early lifestyle may influence the composition of the gut flora in childhood obesity, such as the rate and intake of high-energy foods, low levels of physical activity, may persist into adulthood, thus, early lifestyle interventions may improve the composition of the gut flora in obese children. Adipose Axis plays an important role in the development of obesity. Adipose tissue is characterized by increased expression of nucleoside diphosphate-linked molecule X-type motif 2 (NUDT2), amphiphilic protein AMPH genes, which encode proteins that all play important roles in the CNS. NUDT2 is associated with intellectual disability. Furthermore, amphiphysin (AMPH) is involved in glutamatergic signaling, ganglionic synapse development, and maturation, which is associated with mild cognitive impairment (MCI) and Alzheimer's disease (AD). All of the above studies show that obesity is closely related to cognitive decline in patients. Animal experiments have confirmed that obesity causes changes in cognitive function. For example, high-fat diets rich in long- and medium-chain saturated fatty acids may adversely affect cognitive function in obese mice. This process may be attributed to the Short-Chain Fatty Acid (SCFA)-rich high-fat diet (HFD) activating enterocyte TLR signaling, especially TLR-2 and TLR-4, altering the downstream MyD88-4 signaling, thereby impacting the downstream MyD88-NF-κB signaling cascade and up-regulating the levels of pro-inflammatory factors and lipopolysaccharide (LPS). These changes result in the loss of integrity of the intestinal mucosa and cause an imbalance in the internal environment. Obesity may lead to the disruption of the intestinal flora and damage the intestinal barrier function, causing intestinal flora dysbiosis. In recent years, a growing number of studies have investigated the relationship between obesity and the intestinal flora. For example, high-fat and high-sugar diets have been found to lead to the thinning of the mucus layer of the colon, a decrease in the number of tight junction proteins, and an increase in intestinal permeability in mice. Such changes alter the composition of intestinal microorganisms, allow endotoxins into the blood circulation, and induce neuroinflammation and brain damage. Therefore, obesity affects cognitive function and is even hereditary. This paper reviews the obesity-induced cognitive dysfunction, the underlying mechanisms, the research progress of intestinal flora dysregulation in obese patients, the relationship between intestinal flora and cognitive function changes, and the research progress on intestinal flora dysregulation in obese patients. We want to regulate the internal environment of obese patients from the perspective of intestinal flora, improving the cognitive function of obese patients, and prevent obesity-induced changes in related neurological functions.

Permeability Benchmarking: Guidelines for Comparing in Silico, in Vitro, and in Vivo Measurements

Permeability is a measure of the degree to which cells can transport molecules across biological barriers. Units of permeability are distance per unit time (typically cm/s), where accurate measurements are needed to define drug delivery in homeostasis and to model dysfunction occurring during disease. This perspective offers a set of community-led guidelines to benchmark permeability data across multidisciplinary approaches and different biological contexts. First, we lay out the analytical framework for three methodologies to calculate permeability: in silico assays using either transition-based counting or the inhomogeneous-solubility diffusion approaches, in vitro permeability assays using cells cultured in 2D or 3D geometries, and in vivo assays utilizing in situ brain perfusion or multiple time-point regression analysis. Then, we demonstrate a systematic benchmarking of in silico to both in vitro and in vivo, depicting the ways in which each benchmarking is sensitive to the choices of assay design. Finally, we outline seven recommendations for best practices in permeability benchmarking and underscore the significance of tailored permeability assays in driving advancements in drug delivery research and development. Our exploration encompasses a discussion of "generic" and tissue-specific biological barriers, including the blood-brain barrier (BBB), which is a major hurdle for the delivery of therapeutic agents into the brain. By addressing challenges in reconciling simulated data with experimental assays, we aim to provide insights essential for optimizing accuracy and reliability in permeability modeling.

Bioinformatics insights into mitochondrial and immune gene regulation in Alzheimer's disease

BACKGROUND

There is growing evidence that the pathogenesis of Alzheimer's disease is closely linked to the resident innate immune cells of the central nervous system, including microglia and astrocytes. Mitochondrial dysfunction in microglia has also been reported to play an essential role in the pathogenesis of AD and other neurological diseases. Therefore, finding the mitochondrial and immune-related gene (MIRG) signatures in AD can be significant in diagnosing and treating AD.

METHODS

In this study, the intersection of the differentially expressed genes (DEGs) from the GSE109887 cohort, immune-related genes (IRGs) obtained from WGCNA analysis, and mitochondria-related genes (MRGs) was taken to identify mitochondria-immune-related genes (MIRGs). Then, using machine learning algorithms, biomarkers with good diagnostic value were selected, and a nomogram was constructed. Subsequently, we further analyzed the signaling pathways and potential biological mechanisms of the biomarkers through gene set enrichment analysis, prediction of transcription factors (TFs), miRNAs, and drug prediction.

RESULTS

Using machine learning algorithms, five biomarkers (TSPO, HIGD1A, NDUFAB1, NT5DC3, and MRPS30) were successfully identified, and a nomogram model with strong diagnostic ability and accuracy (AUC > 0.9) was constructed. In addition, single-gene enrichment analysis revealed that NDUFAB1 was significantly enriched in pathways associated with diseases, such as Alzheimer's and Parkinson's, providing valuable insights for future clinical research on Alzheimer's in the context of mitochondrial-immune interactions. Interestingly, brain tissue pathology showed neuronal atrophy and demyelination in AD mice, along with a reduction in Nissl bodies. Furthermore, the escape latency of AD mice was significantly longer than that of the control group. After platform removal, there was a notable increase in the path complexity and time required to reach the target quadrant, suggesting a reduction in spatial memory capacity in AD mice. Moreover, qRT-PCR validation confirmed that the mRNA expression of the five biomarkers was consistent with bioinformatics results. In AD mice, TSPO expression was increased, while HIGD1A, NDUFAB1, NT5DC3, and MRPS30 expressions were decreased. However, peripheral blood samples did not show expression of HIGD1A or MRPS30. These findings provide new insights for research on Alzheimer's disease in the context of mitochondrial-immune interactions, further exploring the pathogenesis of Alzheimer's disease and offering new perspectives for the clinical development of novel drugs.

CONCLUSIONS

Five mitochondrial and immune biomarkers, i.e., TSPO, HIGD1A, NDUFAB1, NT5DC3, and MRPS30, with diagnostic value in Alzheimer's disease, were screened by machine-learning algorithmic models, which will be a guide for future clinical research of Alzheimer's disease in the mitochondria-immunity-related direction.

Evaluation of zonulin levels in patients with migraine

BACKGROUND

Zonulin regulates permeability in blood-brain and intestinal barriers. The pathophysiology of migraine is based on the effect of neurogenic inflammation. The aim of the current investigation was to examine the serum zonulin level in individuals suffering from migraine.

METHODS

The sample comprised 40 individuals who had migraine and 40 controls. Disease duration, attack duration, attack frequency, Visual Analog Scale (VAS) scores, and comorbidities were available for the migraine group. Serum zonulin levels were evaluated by using the ELISA method.

RESULTS

There were no statistically significant differences between the two groups concerning age or gender (p > 0.05). The zonulin value of patients with migraine was higher when compared to the controls, indicating a significant difference (p = 0.037; p < 0.05). The zonulin level did not correlate with disease duration, attack duration, VAS score, or attack frequency (p > 0.05). The receiver operating characteristic curve analysis of zonulin revealed a cut-off value of 30.58 and above, at which it had 52.50% sensitivity, 77.5% specificity, 70% positive predictive value, and 62% a negative predictive value. The area under the curve was 63.6%, and the standard error value was 6.3%. The analysis also showed a statistically significant correlation between migraine diagnosis and a zonulin level of 30.58 (p = 0.006; p < 0.01).

CONCLUSIONS

Elevated zonulin levels in patients with migraine support the disruption of the intestinal barrier and neuroinflammation in these patients. The zonulin level may be a predictive biomarker of migraine. Multicenter, randomized trials are needed to evaluate treatments for intestinal permeability and zonulin levels in migraine patients.

Lysosome-Targeting Protein Degradation Through Endocytosis Pathway Triggered by Polyvalent Nano-Chimera for AD Therapy

The excessive up-regulation of receptor for advanced glycation end products (RAGE), a well-known pathological marker, drives the onset and progression of Alzheimer's disease. Although lysosome-targeting protein degradation has emerged as an effective therapeutic modality, the limited lysosome-sorting efficacy greatly hindered the degradation efficiency of target proteins. Herein, a lysosome-shuttle-like nano-chimera (endoTAC) is proposed based on polyvalent receptor binding mode for enhanced RAGE degradation as well as precise drug delivery. The endoTAC shows a high affinity to RAGE and enhances RAGE degradation due to its polyvalent-interaction with RAGE. Additionally, endoTAC features increased accumulation in diseased brain and shows promise as a precise brain delivery system. After loading with simvastatin, the SV@endoTAC proves to successfully reverse pathological features both in vitro and in vivo. The work proposes that the combination of a lysosome-targeting chimera and an effective drug delivery system can be promising in Alzheimer's disease therapy.

Modulating the blood-brain barrier in CNS disorders: A review of the therapeutic implications of secreted protein acidic and rich in cysteine (SPARC)

Secreted protein acidic and rich in cysteine (SPARC), an essential stromal cell protein, plays a crucial role in angiogenesis and maintaining endothelial barrier function. This protein is expressed by diverse cell types, including endothelial cells, fibroblasts, and macrophages, with increased expression found in regions of tissues undergoing active remodeling, repair, and proliferation. The role of SPARC in non-neural tissues is of significant interest. In the central nervous system (CNS), SPARC is highly expressed in blood vessels during early development. It becomes down-regulated as the brain matures, a pattern consistent with its role in angiogenesis and blood-brain barrier (BBB) establishment. In this review, we explore the multifaceted roles of SPARC in regulating CNS disorders, particularly its action in angiogenesis, inflammatory responses, neural system development and repair, barrier establishment, maintenance of BBB function, and the pathogenesis of CNS disorders triggered by BBB dysfunction.

Tracer kinetic model detecting heterogeneous blood-brain barrier permeability to water and contrast agent in Alzheimer's disease and dementia with Lewy bodies

INTRODUCTION

Blood-brain barrier (BBB) breakdown is essential in Alzheimer's disease (AD) and dementia with Lewy bodies (DLB), whereas the variability in BBB permeability to water and contrast agent is less clear.

METHODS

We investigated BBB permeability to water and contrast agent simultaneously using a novel tracer kinetic model for dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in 42 AD patients, 22 DLB patients, and 22 healthy controls. All participants underwent clinical, cognitive, and MRI assessments.

RESULTS

AD patients exhibited a significant reduction in the water exchange rates across the BBB, whereas DLB patients showed a significant increase in BBB permeability to contrast agent. Moreover, BBB permeability to both water and contrast agent in multiple brain regions demonstrated correlations with clinical severity.

DISCUSSION

The simultaneous evaluation of BBB permeability to water and contrast agent based on the proposed model highlights the heterogeneous patterns of BBB breakdown in AD and DLB.

HIGHLIGHTS

We measured blood-brain barrier (BBB) permeability to water and contrast agent based on dynamic contrast-enhanced magnetic resonance imaging. Alzheimer's disease (AD) is characterized by lower water exchange rates across the BBB. Dementia with Lewy bodies exhibits higher BBB permeability to contrast agent. BBB permeability is related to cognitive impairment and disease burden. BBB permeability to water was negatively associated with that to contrast agent.

P2Y1 receptor in Alzheimer's disease

Alzheimer's disease is the most frequent form of dementia characterized by the deposition of amyloid-beta plaques and neurofibrillary tangles consisting of hyperphosphorylated tau. Targeting amyloid-beta plaques has been a primary direction for developing Alzheimer's disease treatments in the last decades. However, existing drugs targeting amyloid-beta plaques have not fully yielded the expected results in the clinic, necessitating the exploration of alternative therapeutic strategies. Increasing evidence unravels that astrocyte morphology and function alter in the brain of Alzheimer's disease patients, with dysregulated astrocytic purinergic receptors, particularly the P2Y1 receptor, all of which constitute the pathophysiology of Alzheimer's disease. These receptors are not only crucial for maintaining normal astrocyte function but are also highly implicated in neuroinflammation in Alzheimer's disease. This review delves into recent insights into the association between P2Y1 receptor and Alzheimer's disease to underscore the potential neuroprotective role of P2Y1 receptor in Alzheimer's disease by mitigating neuroinflammation, thus offering promising avenues for developing drugs for Alzheimer's disease and potentially contributing to the development of more effective treatments.

Aging disrupts blood-brain and blood-spinal cord barrier homeostasis, but does not increase paracellular permeability

Blood-CNS barriers protect the CNS from circulating immune cells and damaging molecules. It is thought barrier integrity becomes disrupted with aging, contributing to impaired CNS function. Using genome-wide and targeted molecular approaches, we found aging affected expression of predominantly immune invasion and pericyte-related genes in CNS regions investigated, especially after middle age, with spinal cord being most impacted. We did not find significant perturbation of endothelial cell junction genes or proteins, nor were vascular density or pericyte coverage affected by aging. We evaluated barrier paracellular permeability using small molecular weight tracers, serum protein extravasation, CNS water content, and iron labelling measures. We found no evidence for age-related increased barrier permeability in any of these tests. We conclude that blood-brain (BBB) and blood-spinal cord barrier (BSCB) paracellular permeability does not increase with normal aging in mouse. Whilst expression changes were not associated with increased permeability, they may represent an age-related primed state whereby additional insults cause increased leakiness.

Brain targeted polymeric micelles as drug carriers for ischaemic stroke treatment

Ischaemic stroke is a central nervous system disease with high morbidity, recurrence and mortality rates. Thrombolytic and neuroprotective therapies are the main therapeutic strategies for ischaemic stroke, however, the poor delivery efficiency of thrombolytic and neuroprotective drugs to the brain limits their clinical application. So far, the development of nanomedicine has brought opportunities for the above challenges, which can not only realise the effective accumulation of drugs in the target site, but also improve the pharmacokinetic behaviour of the drugs. Among the most rapidly developing nanoparticles, micelles gradually emerging as an effective strategy for ischaemic stroke treatment due to their own unique advantages. This review provided an overview of targeted and response-release micelles based on the physicochemical properties of the ischaemic stroke microenvironment, summarised the targeting strategies for delivering micellar formulations to the thrombus, blood-brain barrier, and brain parenchyma, and finally described the potentials and challenges of polymeric micelles in the treatment of ischaemic stroke.

Endothelial Cells and the Blood-Brain Barrier: Critical Determinants of Ineffective Reperfusion in Stroke

Ineffective reperfusion remains a critical challenge in neurointerventional treatment following ischemic stroke, with the integrity of the blood-brain barrier (BBB) being a key determinant of patient outcomes. This review explores the distinctive characteristics and roles of brain endothelial cells (ECs) in the context of stroke and ineffective reperfusion. We examine the unique properties of brain ECs compared to their counterparts in other tissues, focusing on their pathophysiological changes, functional impairments and the inflammatory cascades that follow stroke. Differences in gene expression between brain ECs and those in other organs offer deeper insights into their role in neuroprotective therapies. Additionally, drawing parallels between brain ECs and ECs from organs with similar ischemia-reperfusion injury profiles may inspire novel therapeutic approaches. This review highlights the critical importance of understanding the nuanced roles of ECs in BBB regulation, which ultimately impacts reperfusion outcomes.

SIV infection induces alterations in gene expression and loss of interneurons in Rhesus Macaque frontal cortex during early systemic infection

Understanding the neurobiological mechanisms underlying HIV-associated neurocognitive decline in people living with HIV is frequently complicated by an inability to analyze changes across the course of the infection and frequent presence of comorbid psychiatric and substance use disorders. Preclinical non-human primate simian immunodeficiency virus (SIV) models help address these shortcomings. However, SIV studies frequently target protracted endpoints, limiting our understanding of the neuromolecular alterations during the early post-infection window. To begin to address this knowledge gap, we utilized single nuclei transcriptomics to examine frontal cortex samples of rhesus macaques 10- and 20-days post-SIV infection, compared to non-infected controls. We identify and validated a decrease in inhibitory neurons during the early post infection window, representing a potential substrate of longer-term injury and neurocognitive impairment in people living with HIV. Differential expression identified alterations in cellular subtype gene expression that persisted over the 20-day time course and short-lived differences only detected at 10-days post-SIV infection. In silico predicted regulatory mechanisms and dysregulated neural signaling pathways are presented. Analysis of cell-cell interaction networks identify altered signal pathways in the frontal cortex that may represent regional alterations in cell-cell communications. In total, these results identify cell type-specific molecular mechanisms putatively capable of underlying long-term neurocognitive alterations in persons living with HIV.

Muscarinic acetylcholine receptor 3 localized to primary endothelial cilia regulates blood pressure and cognition

We previously demonstrated that the inability of primary endothelial cilia to sense fluid shear stress can lead to nitric oxide (NO) deficiency and cause hypertension (HTN). Decreased biosynthesis of NO contributes to cerebral amyloid angiopathy in Alzheimer's disease (AD) patients through increased deposition of amyloid beta (Aβ). However, the molecular mechanisms underlying the pathogenesis of HTN and AD are incompletely understood. The objective of this study was to examine the pathophysiological roles of vascular primary cilia and muscarinic acetylcholine receptor 3 (CHRM3) in HTN and AD. We discovered, for the first time, that CHRM3 was localized to primary cilia of endothelial and cerebrovascular cells, and that CHRM3 expression was downregulated in cilialess cells. Moreover, CHRM3 activation enhanced cilia length and sensory function in terms of eNOS activation. To further examine the role of vascular CHRM3 in vivo, we showed that endothelial CHRM3 knockout was associated with increased BP and attenuated acetylcholine-mediated vascular relaxation. In addition, endothelial CHRM3 knockout resulted in altered fear behavior. This demonstrates the physiological significance of endothelial CHRM3 signaling and primary cilia-derived NO production as an important mechanism in the control of BP and cognition.

Activation of Wnt/β-catenin in neural progenitor cells regulates blood-brain barrier development and promotes neuroinflammation

The central nervous system (CNS) requires specialized blood vessels to support neural function within specific microenvironments. During neurovascular development, endothelial Wnt/β-catenin signaling is required for BBB development within the brain parenchyma, whereas fenestrated blood vessels that lack BBB properties do not require Wnt/β-catenin signaling. Here, we used zebrafish to further characterize this phenotypic heterogeneity of the CNS vasculature. Using transgenic reporters of Wnt/β-catenin transcriptional activity, we found an inverse correlation between activated Wnt/β-catenin signaling in endothelial cells (ECs) versus non-ECs within these distinct microenvironments. Our results indicated that the level of Wnt/β-catenin signaling in non-ECs may regulate Wnt/β-catenin activity in adjacent ECs. To further test this concept, we generated a transgenic Tet-On inducible system to drive constitutively active β-catenin expression in neural progenitor cells (NPCs). We found that dose-dependent activation of Wnt/β-catenin in NPCs caused severe deficiency in CNS angiogenesis and BBB development. Additionally, we discovered a significant increase in the proliferation of microglia and infiltration of peripheral neutrophils indicative of a stereotypical neuroinflammatory response. In conclusion, our results demonstrate the importance of proper Wnt/β-catenin signaling within specific CNS microenvironments and highlights the potentially deleterious consequences of aberrant Wnt activation.

Extracellular Vesicles as Tools for Crossing the Blood-Brain Barrier to Treat Lysosomal Storage Diseases

Extracellular vesicles (EVs) are nanosized, membrane-bound structures that have emerged as promising tools for drug delivery, especially in the treatment of lysosomal storage disorders (LSDs) with central nervous system (CNS) involvement. This review highlights the unique properties of EVs, such as their biocompatibility, capacity to cross the blood-brain barrier (BBB), and potential for therapeutic cargo loading, including that of enzymes and genetic material. Current therapies for LSDs, like enzyme replacement therapy (ERT), often fail to address neurological symptoms due to their inability to cross the BBB. EVs offer a viable alternative, allowing for targeted delivery to the CNS and improving therapeutic outcomes. We discuss recent advancements in the engineering and modification of EVs to enhance targeting, circulation time and cargo stability, and provide a detailed overview of their application in LSDs, such as Gaucher and Fabry diseases, and Sanfilippo syndrome. Despite their potential, challenges remain in scaling production, ensuring isolation purity, and meeting regulatory requirements. Future developments will focus on overcoming these barriers, paving the way for the clinical translation of EV-based therapies in LSDs and other CNS disorders.