Astrocyte Involvement in Blood-Brain Barrier Function: A Critical Update Highlighting Novel, Complex, Neurovascular Interactions

Temperature Regulates Astroglia Morphogenesis Through Thermosensory Circuitry in Caenorhabditis elegans

Astrocytes are the most abundant type of macroglia in the brain and play crucial roles in regulating neural development and functions. The diverse functions of astrocytes are largely determined by their morphology, which is regulated by genetic and environmental factors. However, whether and how the astrocyte morphology is affected by temperature remains largely unknown. Here we discovered that elevated cultivation temperature (26°C) stimulates Caenorhabditis elegans ventral CEPsh glia endfoot extension during early developmental stages. This extension depends on the activation of glutamate AWC neurons, which inhibit the postsynaptic cholinergic AIY interneurons through glutamate-gated chloride channels, GLC-3 and GLC-4. In responding to the thermosensory signal, the guanyl-nucleotide exchange factor EPHX-1 and Rho GTPase CDC-42/Cdc42 in the glia facilitate the endfoot extension via F-actin assembly. This study elucidates the significant role of thermosensory circuitry in glia morphogenesis and the underlying molecular mechanism.

Astrocytes of the hippocampus and responses to periprandial neuroendocrine hormones

Astrocytes have risen as stars in the field of energy homeostasis and neurocognitive function, acting as a bridge of communication between the periphery and the brain, providing metabolic support, signaling via gliotransmitters, and altering synaptic communication. Dietary factors and energy state have a profound influence on hippocampal function, and the hippocampus is critical for appropriate behavioral responses associated with feeding and internal hunger cues (being in the fasted or full state), but how the hippocampus senses periprandial status and is impacted by diet is largely unknown. Periprandial hormones act within the hippocampus to modulate processes involved in hippocampal-dependent learning and memory function and astrocytes likely play an important role in modulating this signaling. In addition to periprandial hormones, astrocytes are positioned to respond to changes in circulating nutrients like glucose. Here, we review literature investigating how astrocytes mediate changes in hippocampal function, highlighting astrocyte location, morphology, and function in the context of integrating glucose metabolism, neuroendocrine hormone action, and/or cognitive function in the hippocampus. Specifically, we discuss research findings on the effects of insulin, ghrelin, leptin, and GLP-1 on glucose homeostasis, neural activity, astrocyte function, and behavior in the hippocampus. Because obesogenic diets impact neuroendocrine hormones, astrocytes, and cognitive function, we also discuss the effects of diet and diet-induced obesity on these parameters.

A novel optimized orthotopic mouse model for brain metastasis with sustained cerebral blood circulation and capability of multiple delivery

Brain metastasis is thought to be related to the high mortality and poor prognosis of lung cancer. Despite significant advances in the treatment of primary lung cancer, the unique microenvironment of the brain renders current therapeutic strategies largely ineffective against brain metastasis. The lack of effective drugs for brain metastasis treatment is primarily due to the incomplete understanding of the mechanisms underlying its initiation and progression. Currently, our understanding of brain metastasis remains limited, primarily due to the absence of appropriate models that can realistically simulate the entire process of tumor cell detachment from the primary site, circulation through the bloodstream, and eventual colonization of the brain. Therefore, there is a pressing need to develop more suitable lung cancer brain metastasis models that can effectively replicate these critical stages of metastasis. Here, based on the traditional carotid artery injection model, we established a novel orthotopic mouse model by using a light-controlled hydrogel to repair the puncture site on the carotid artery, with sustained cerebral blood circulation and the capability of multiple delivery cancer cell to mimic lung cancer brain metastasis. The optimized orthotopic mouse model significantly reduced cerebral ischemia and improved cerebral oxygenation by 60% compared to the traditional orthotopic mouse model, enhancing post-operative survival rates. It also showed a reduction in pro-inflammatory cytokines and featured less inflammatory and more resting states of microglial and astrocyte cells. Furthermore, the optimized orthotopic mouse model markedly increased the success rate and absolute number of the metastatic clones in the brain. Additionally, the multiple delivery model based on the optimized orthotopic mouse model substantially augmented the tumor clone number and formation rates compared to single injection in the optimized orthotopic mouse model. This model overcomes previous limitations by maintaining cerebral circulation, providing a more accurate simulation of the continuous entry of tumor cells into cerebral circulation. It offers a robust platform for studying the interactions of cancer cells with the brain microenvironment and testing new therapeutic approaches.

Interrogating mediators of single-cell transcriptional changes in the acute damaged cerebral cortex: Insights into endothelial-astrocyte interactions

Traumatic brain injury (TBI) induces complex cellular and molecular changes, challenging recovery and therapeutic development. Although molecular pathways have been implicated in TBI pathology, the cellular specificity of these mechanisms remains underexplored. Here, we investigate the role of endothelial cell (EC) EphA4, a receptor tyrosine kinase receptor involved in axonal guidance, in modulating cell-specific transcriptomic changes within the damaged cerebral cortex. Utilizing single-cell RNA sequencing (scRNA-seq) in an experimental TBI model, we mapped transcriptional changes across various cell types, with a focus on astrocytes and ECs. Our analysis reveals that EC-specific knockout (KO) of EphA4 triggers significant alterations in astrocyte gene expression and shifts predominate subclusters. We identified six distinct astrocyte clusters (C0-C5) in the damaged cortex including as C0-Mobp/Plp1+; C1-Slc1a3/Clu+; C2-Hbb-bs/Hba-a1/Ndrg2+; C3-GFAP/Lcn2+; C4-Gli3/Mertk+, and C5-Cox8a+. We validate a new Sox9+ cluster expressing Mertk and Gas, which mediates efferocytosis to facilitate apoptotic cell clearance and anti-inflammatory responses. Transcriptomic and CellChat analyses of EC-KO cells highlights upregulation of neuroprotective pathways, including increased amyloid precursor protein (APP) and Gas6. Key pathways predicted to be modulated in astrocytes from EC-KO mice include oxidative phosphorylation and FOXO signaling, mitochondrial dysfunction and ephrin B signaling. Concurrently, metabolic and signaling pathways in endothelial cells-such as ceramide and sphingosine phosphate metabolism and NGF-stimulated transcription-indicate an adaptive response to a metabolically demanding post-injury hypoxic environment. These findings elucidate potential interplay between astrocytic and endothelial responses as well as transcriptional networks underlying cortical tissue damage.

Molecular Motors in Blood-Brain Barrier Maintenance by Astrocytes

The blood-brain barrier (BBB) comprises distinct cell types, including endothelial cells, pericytes, and astrocytes, and is essential for central nervous system (CNS) homeostasis by selectively regulating molecular transport and maintaining integrity. In particular, astrocytes are essential for BBB function, as they maintain BBB integrity through their end-feet, which form a physical and biochemical interface that enhances endothelial cell function and barrier selectivity. Moreover, they secrete growth factors like vascular endothelial growth factor (VEGF) and transforming growth factor-beta (TGF-β), which regulate tight junction (TJ) proteins (e.g., claudins and occludins) crucial for limiting paracellular permeability. Molecular motors like kinesins, dynein, and myosins are essential for these astrocyte functions. By facilitating vesicular trafficking and protein transport, they are essential for various functions, including trafficking of junctional proteins to support BBB integrity, the proper mitochondria localization within astrocyte processes for efficient energy supply, the polarized distribution of aquaporin (AQP)-4 at astrocyte end-feet for regulating water homeostasis across the BBB, and the modulation of neuroinflammatory responses. Moreover, myosin motors modulate actomyosin dynamics to regulate astrocyte process outgrowth, adhesion, migration, and morphology, facilitating their functional roles. Thus, motor protein dysregulation in astrocytes can compromise BBB function and integrity, increasing the risk of neurodegeneration. This review explores the complex interplay between astrocytes and molecular motors in regulating BBB homeostasis, which represents an attractive but poorly explored area of research.

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.

The Triad of Blood-Brain Barrier Integrity: Endothelial Cells, Astrocytes, and Pericytes in Perinatal Stroke Pathophysiology

Pediatric stroke, a significant cause of long-term neurological deficits in children, often arises from disruptions within neurovascular unit (NVU) components. The NVU, a dynamic ensemble of astrocytes, endothelial cells, pericytes, and microglia, is vital for maintaining cerebral homeostasis and regulating vascular brain development. Its structural integrity, particularly at the blood-brain barrier (BBB), depends on intercellular junctions and the basement membrane, which together restrict paracellular transport and shield the brain from systemic insults. Dysfunction in this intricate system is increasingly linked to pediatric stroke and related cerebrovascular conditions. Mutations disrupting endothelial cell adhesion or pericyte-endothelial interactions can compromise BBB stability, leading to pathological outcomes such as intraventricular hemorrhage in the germinal matrix, a hallmark of vascular brain immaturity. Additionally, inflammation, ferroptosis, necroptosis, and autophagy are key cellular processes influencing brain damage and repair. Excessive activation of these mechanisms can exacerbate NVU injury, whereas targeted therapeutic modulation offers potential pathways to mitigate damage and support recovery. This review explores the cellular and molecular mechanisms underlying NVU dysfunction, BBB disruption, and subsequent brain injury in pediatric stroke. Understanding the interplay between genetic mutations, environmental stressors, and NVU dynamics provides new insights into stroke pathogenesis. The susceptibility of the germinal matrix to vascular rupture further emphasizes the critical role of NVU integrity in early brain development. Targeting inflammatory pathways and cell death mechanisms presents promising strategies to preserve NVU function and improve outcomes for affected neonates.

Cell-cell communications in the brain of hepatic encephalopathy: The neurovascular unit

Many patients with liver diseases are exposed to the risk of hepatic encephalopathy (HE). The incidence of HE in liver patients is high, showing various symptoms ranging from mild symptoms to coma. Liver transplantation is one of the ways to overcome HE. However, not all patients can receive liver transplantation. Moreover, patients who have received liver transplantation have limitations in that they are vulnerable to hepatocellular carcinoma, allograft rejection, and infection. To find other therapeutic strategies, it is important to understand pathological factors and mechanisms that lead to HE after liver disease. Oxidative stress, inflammatory response, hyperammonaemia and metabolic disorders seen after liver diseases have been reported as risk factors of HE. These are known to affect the brain and cause HE. These peripheral pathological factors can impair the blood-brain barrier, cause it to collapse and damage the neurovascular unit component of multiple cells, including vascular endothelial cells, astrocytes, microglia, and neurons, leading to HE. Many previous studies on HE have suggested the impairment of neurovascular unit and cell-cell communication in the pathogenesis of HE. This review focuses on pathological factors that appear in HE, cell type-specific pathological mechanisms, miscommunication/incorrect relationships, and therapeutic candidates between brain cells in HE. This review suggests that regulating communications and interactions between cells may be important in overcoming HE.

Innate immune sensors and regulators at the blood brain barrier: focus on toll-like receptors and inflammasomes as mediators of neuro-immune crosstalk and inflammation

Cerebral endothelial cells (CEC) that form the brain capillaries are the principal constituents of the blood brain barrier (BBB), the main active interface between the blood and the brain which plays a protective role by restricting the infiltration of pathogens, harmful substances and immune cells into the brain while allowing the entry of essential nutrients. Aberrant CEC function often leads to increased permeability of the BBB altering the bidirectional communication between the brain and the bloodstream and facilitating the extravasation of immune cells into the brain. In addition to their role as essential gatekeepers of the BBB, CEC exhibit immune cell properties as they can receive and transmit signals between the blood and the brain partly via release of inflammatory effectors in pathological conditions. Cerebral endothelial cells express innate immune receptors, including toll like receptors (TLRs) and inflammasomes which are the first sensors of exogenous or endogenous dangers and initiators of immune and inflammatory responses which drive neural dysfunction and degeneration. Accumulating evidence indicates that activation of TLRs and inflammasomes in CEC compromises BBB integrity, promotes aberrant neuroimmune interactions and modulates both systemic and neuroinflammation, common pathological features of neurodegenerative and psychiatric diseases and central nervous system (CNS) infections and injuries. The goal of the present review is to provide an overview of the pivotal roles played by TLRs and inflammasomes in CEC function and discuss the molecular and cellular mechanisms by which they contribute to BBB disruption and neuroinflammation especially in the context of traumatic and ischemic brain injuries and brain infections. We will especially focus on the most recent advances and literature reports in the field to highlight the knowledge gaps. We will discuss future research directions that can advance our understanding of the central contribution of innate immune receptors to CEC and BBB dysfunction and the potential of innate immune receptors at the BBB as promising therapeutic targets in a wide variety of pathological conditions of the brain.

Advancing neurological disorders therapies: Organic nanoparticles as a key to blood-brain barrier penetration

The blood-brain barrier (BBB) plays a vital role in protecting the central nervous system (CNS) by preventing the entry of harmful pathogens from the bloodstream. However, this barrier also presents a significant obstacle when it comes to delivering drugs for the treatment of neurodegenerative diseases and brain cancer. Recent breakthroughs in nanotechnology have paved the way for the creation of a wide range of nanoparticles (NPs) that can serve as carriers for diagnosis and therapy. Regarding their promising properties, organic NPs have the potential to be used as effective carriers for drug delivery across the BBB based on recent advancements. These remarkable NPs have the ability to penetrate the BBB using various mechanisms. This review offers a comprehensive examination of the intricate structure and distinct properties of the BBB, emphasizing its crucial function in preserving brain balance and regulating the transport of ions and molecules. The disruption of the BBB in conditions such as stroke, Alzheimer's disease, and Parkinson's disease highlights the importance of developing creative approaches for delivering drugs. Through the encapsulation of therapeutic molecules and the precise targeting of transport processes in the brain vasculature, organic NP formulations present a hopeful strategy to improve drug transport across the BBB. We explore the changes in properties of the BBB in various pathological conditions and investigate the factors that affect the successful delivery of organic NPs into the brain. In addition, we explore the most promising delivery systems associated with NPs that have shown positive results in treating neurodegenerative and ischemic disorders. This review opens up new possibilities for nanotechnology-based therapies in cerebral diseases.

Role of Glial Cells and Receptors in Schizophrenia Pathogenesis

The specific pathogeneses of schizophrenia (SCZ) remain an enigma despite extensive research that has implicated both genetic and environmental factors. Recent revelations that dysregulated immune system caused by glial cell overactivation result in neuroinflammation, a key player in neurodegenerative as well as neuropsychiatric disorders including SCZ are providing novel clues on potential therapeutic interventions. Here, we review the roles of glial cells (Dr. Arne Schousboe's passion) and two of their most implicated receptors, toll-like receptors (TLRs), and nicotinic cholinergic receptors, in SCZ pathology with suggestions as potential targets in this devastating neuropsychiatric condition.

Blood-Brain Barrier Disruption in Schizophrenia: Insights, Mechanisms, and Future Directions

The blood-brain barrier (BBB) plays a crucial role in maintaining the homeostasis of the central nervous system by regulating solute transport and preventing neurotoxic substances from infiltrating brain tissue. In schizophrenia, emerging evidence identifies BBB dysfunction as a key pathophysiological factor associated with neuroinflammation, tight junction abnormalities, and endothelial dysfunction. Recent advancements in neuroimaging techniques, such as arterial spin labeling (ASL), have provided valuable tools for investigating BBB permeability and its role in disease progression. This review synthesizes findings from postmortem studies, serum and cerebrospinal fluid biomarker analyses, and advanced neuroimaging research to elucidate BBB alterations in schizophrenia. It highlights the mechanistic roles of tight junction protein dysregulation, neurovascular unit dysfunction, and immune responses in disrupting BBB integrity. Furthermore, the review examines the bidirectional effects of antipsychotic medications on BBB, addressing both therapeutic opportunities and potential challenges. By emphasizing the pivotal role of BBB dysfunction in schizophrenia pathogenesis, this review underscores its translational potential. Through the integration of multidisciplinary evidence, it lays the foundation for innovative diagnostic approaches and therapeutic strategies, enhancing our understanding of schizophrenia's complex pathophysiology.

Nanoparticle Interactions with the Blood Brain Barrier: Insights from Drosophila and Implications for Human Astrocyte Targeted Therapies

This review explores the intricate connections between Drosophila models and the human blood-brain barrier (BBB) with nanoparticle-based approaches for neurological treatment. Drosophila serves as a powerful model organism due to its evolutionary conservation of key biological processes, particularly in the context of the BBB, which is formed by glial cells that share structural and functional similarities with mammalian endothelial cells. Recent advancements in nanoparticle technology have highlighted their potential for effective drug delivery across the BBB, utilizing mechanisms such as passive diffusion, receptor-mediated transcytosis, and carrier-mediated transport. The ability to engineer nanoparticles with specific physicochemical properties-such as size, surface charge, and functionalization-enhances their targeting capabilities, particularly towards astrocytes, which play a crucial role in maintaining BBB integrity and responding to neuroinflammation. Insights gained from Drosophila studies have informed the design of personalized nanomedicine strategies aimed at treating neurodegenerative diseases, including Alzheimer's, Parkinson's disease etc. As research progresses, the integration of findings from Drosophila models with emerging humanized BBB systems will pave the way for innovative therapeutic approaches that improve drug delivery and patient outcomes in neurological disorders.

The Crucial Role of the Blood-Brain Barrier in Neurodegenerative Diseases: Mechanisms of Disruption and Therapeutic Implications

The blood-brain barrier (BBB) is a crucial structure that maintains brain homeostasis by regulating the entry of molecules and cells from the bloodstream into the central nervous system (CNS). Neurodegenerative diseases such as Alzheimer's and Parkinson's disease, as well as ischemic stroke, compromise the integrity of the BBB. This leads to increased permeability and the infiltration of harmful substances, thereby accelerating neurodegeneration. In this review, we explore the mechanisms underlying BBB disruption, including oxidative stress, neuroinflammation, vascular dysfunction, and the loss of tight junction integrity, in patients with neurodegenerative diseases. We discuss how BBB breakdown contributes to neuroinflammation, neurotoxicity, and the abnormal accumulation of pathological proteins, all of which exacerbate neuronal damage and facilitate disease progression. Furthermore, we discuss potential therapeutic strategies aimed at preserving or restoring BBB function, such as anti-inflammatory treatments, antioxidant therapies, and approaches to enhance tight junction integrity. Given the central role of the BBB in neurodegeneration, maintaining its integrity represents a promising therapeutic approach to slow or prevent the progression of neurodegenerative diseases.

Advancing Alzheimer's Disease Modelling by Developing a Refined Biomimetic Brain Microenvironment for Facilitating High-Throughput Screening of Pharmacological Treatment Strategies

Alzheimer's disease (AD) poses a significant worldwide health challenge, requiring novel approaches for improved models and treatment development. This comprehensive review emphasises the systematic development and improvement of a biomimetic brain environment to address the shortcomings of existing AD models and enhance the efficiency of screening potential drug treatments. We identify drawbacks in traditional models and emphasise the necessity for more physiologically accurate systems through an in-depth analysis of current literature. This review aims to study the development of an advanced AD model that accurately replicates key AD pathophysiological aspects using cutting-edge biomaterials and microenvironment design. Incorporating biomolecular elements like Tau proteins and beta-amyloid (Aβ) plaques improve the accuracy of illustrating disease mechanisms. The expected results involve creating a solid foundation for high-throughput screening with enhanced scalability, translational significance, and the possibility of speeding up drug discovery. Thus, this review fills the gaps in AD modelling and shows potential for creating precise and efficient drug treatments for AD.

The pleiotropic effects of statins: a comprehensive exploration of neurovascular unit modulation and blood-brain barrier protection

The blood-brain barrier (BBB) is the most central component of the neurovascular unit (NVU) and is crucial for the maintenance of the internal environment of the central nervous system and the regulation of homeostasis. A multitude of neuroprotective agents have been developed to exert neuroprotective effects and improve the prognosis of patients with ischemic stroke. These agents have been designed to maintain integrity and promote BBB repair. Statins are widely used as pharmacological agents for the treatment and prevention of ischemic stroke, making them a cornerstone in the pharmacological armamentarium for this condition. The primary mechanism of action is the reduction of serum cholesterol through the inhibition of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, which results in a decrease in low-density lipoprotein cholesterol (LDL-C) and an increase in cholesterol clearance. Nevertheless, basic and clinical research has indicated that statins may exert additional pleiotropic effects beyond LDL-C reduction. Previous studies on ischemic stroke have demonstrated that statins can enhance neurological function, reduce inflammation, and promote angiogenic and synaptic processes following ischemic stroke. The BBB has been increasingly recognized for its role in the development and progression of ischemic stroke. Statins have also been found to play a potential BBB protective role by affecting members of the NVU. This review aimed to provide a comprehensive theoretical basis for the clinical application of statins by systematically detailing how statins influence the BBB, particularly focusing on the regulation of the function of each member of the NVU.

Mechanistic exploration of ubiquitination-mediated pathways in cerebral ischemic injury

The ubiquitin-proteasome system (UPS) plays a pivotal role in regulating protein homeostasis and cellular processes, including protein degradation, trafficking, DNA repair, and cell signaling. During cerebral ischemia, ischemic conditions profoundly disrupt UPS activity, leading to proteasomal dysfunction and the accumulation of abnormal proteins. This imbalance contributes to neuronal injury and cell death observed in ischemic stroke. The UPS is intricately linked to various signaling pathways crucial for neuronal survival, inflammation, and cellular stress response, such as NF-κB, TRIM, TRIP, JAK-STAT, PI3K/Akt, and ERK1/2. Alterations in the ubiquitination process can significantly impact the activation and regulation of these pathways, exacerbating ischemic brain injury. Therapeutic approaches targeting the UPS in cerebral ischemia aim to rebalance protein levels, reduce proteotoxic stress, and mitigate neuronal injury. Strategies include proteasome inhibition, targeting specific ubiquitin ligases and deubiquitinating enzymes, and modulating ubiquitination-mediated regulation of key signaling pathways implicated in ischemia-induced pathophysiology. Therefore, the present review discusses the molecular mechanisms underlying UPS dysfunction in ischemic stroke is crucial for developing effective therapeutic interventions. Modulating ubiquitination-mediated pathways through therapeutic interventions targeting specific UPS components holds significant promise for mitigating ischemic brain injury and promoting neuroprotection and functional recovery in patients with cerebral ischemia.

Astrocyte Dysfunction Reflected in Ischemia-Induced Astrocyte-Derived Extracellular Vesicles: A Pilot Study on Acute Ischemic Stroke Patients

Extracellular vesicles (EVs) secreted by astrocytes (ADEVs) mediate numerous biological processes, providing insights into damage, repair, and protection following ischemic stroke (IS). This pilot study aimed to broaden the current knowledge on the astrocyte response to ischemia by dynamically assessing the aquaporin-4 (AQP4) and glial cell line-derived neurotrophic factor (GDNF) as cargo proteins of these vesicles in eighteen acute IS patients and nine controls. EV proteins were detected by Western blotting and followed 24 h (D1), 7 days (D7), and one month (M1) after symptoms onset. The post-ischemic ADEV AQP4 and GDNF levels were higher at D1 compared to the control group (p = 0.006 and p = 0.023). Significant differences were observed in ADEV AQP4 during the three evaluated time points (n = 12, p = 0.013) and between D1 and D7 (z = 2.858, p = 0.012), but not in EV GDNF. There was a positive relationship between the severity of stroke at D1 according to the National Institutes of Health Stroke Scale, and ADEV AQP4 at D1 (r = 0.50, p = 0.031), as well as ADEV GDNF at D1 and D7 (r = 0.49, p = 0.035 and r = 0.53, p = 0.021, respectively). The release of EVs with distinct protein profiles can be an attractive platform for the development of biomarkers in IS.

The Importance of Phosphoinositide 3-Kinase in Neuroinflammation

Neuroinflammation, characterised by the activation of immune cells in the central nervous system (CNS), plays a dual role in both protecting against and contributing to the progression of neurodegenerative diseases, such as Alzheimer's disease (AD) and multiple sclerosis (MS). This review explores the role of phosphoinositide 3-kinase (PI3K), a key enzyme involved in cellular survival, proliferation, and inflammatory responses, within the context of neuroinflammation. Two PI3K isoforms of interest, PI3Kγ and PI3Kδ, are specific to the regulation of CNS cells, such as microglia, astrocytes, neurons, and oligodendrocytes, influencing pathways, such as Akt, mTOR, and NF-κB, that control cytokine production, immune cell activation, and neuroprotection. The dysregulation of PI3K signalling is implicated in chronic neuroinflammation, contributing to the exacerbation of neurodegenerative diseases. Preclinical studies show promise in targeting neuronal disorders using PI3K inhibitors, such as AS605240 (PI3Kγ) and idelalisib (PI3Kδ), which have reduced inflammation, microglial activation, and neuronal death in in vivo models of AD. However, the clinical translation of these inhibitors faces challenges, including blood-brain barrier (BBB) permeability, isoform specificity, and long-term safety concerns. This review highlights the therapeutic potential of PI3K modulation in neuroinflammatory diseases, identifying key gaps in the current research, particularly in the need for brain-penetrating and isoform-specific inhibitors. These findings underscore the importance of future research to develop targeted therapies that can effectively modulate PI3K activity and provide neuroprotection in chronic neurodegenerative disorders.

Intercellular Adhesion Molecule 1 (ICAM-1): An Inflammatory Regulator with Potential Implications in Ferroptosis and Parkinson's Disease

Intercellular adhesion molecule 1 (ICAM-1/CD54), a transmembrane glycoprotein, has been considered as one of the most important adhesion molecules during leukocyte recruitment. It is encoded by the ICAM1 gene and plays a central role in inflammation. Its crucial role in many inflammatory diseases such as ulcerative colitis and rheumatoid arthritis are well established. Given that neuroinflammation, underscored by microglial activation, is a key element in neurodegenerative diseases such as Parkinson's disease (PD), we investigated whether ICAM-1 has a role in this progressive neurological condition and, if so, to elucidate the underpinning mechanisms. Specifically, we were interested in the potential interaction between ICAM-1, glial cells, and ferroptosis, an iron-dependent form of cell death that has recently been implicated in PD. We conclude that there exist direct and indirect (via glial cells and T cells) influences of ICAM-1 on ferroptosis and that further elucidation of these interactions can suggest novel intervention for this devastating disease.

A patient-derived amyotrophic lateral sclerosis blood-brain barrier model for focused ultrasound-mediated anti-TDP-43 antibody delivery

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a rapidly progressing neurodegenerative disorder with minimally effective treatment options. An important hurdle in ALS drug development is the non-invasive therapeutic access to the motor cortex currently limited by the presence of the blood-brain barrier (BBB). Focused ultrasound and microbubble (FUS+ MB) treatment is an emerging technology that was successfully used in ALS patients to temporarily open the cortical BBB. However, FUS+ MB-mediated drug delivery across ALS patients' BBB has not yet been reported. Similarly, the effects of FUS+ MB on human ALS BBB cells remain unexplored.

METHODS

Here we established the first FUS+ MB-compatible, fully-human ALS patient-cell-derived BBB model based on induced brain endothelial-like cells (iBECs) to study anti-TDP-43 antibody delivery and FUS+ MB bioeffects in vitro.

RESULTS

Generated ALS iBECs recapitulated disease-specific hallmarks of BBB pathology, including reduced BBB integrity and permeability, and TDP-43 proteinopathy. The results also identified differences between sporadic ALS and familial (C9orf72 expansion carrying) ALS iBECs reflecting patient heterogeneity associated with disease subgroups. Studies in these models revealed successful ALS iBEC monolayer opening in vitro with no adverse cellular effects of FUS+ MB as reflected by lactate dehydrogenase (LDH) release viability assay and the lack of visible monolayer damage or morphology change in FUS+ MB treated cells. This was accompanied by the molecular bioeffects of FUS+ MB in ALS iBECs including changes in expression of tight and adherens junction markers, and drug transporter and inflammatory mediators, with sporadic and C9orf72 ALS iBECs generating transient specific responses. Additionally, we demonstrated an effective increase in the delivery of anti-TDP-43 antibody with FUS+ MB in C9orf72 (2.7-fold) and sporadic (1.9-fold) ALS iBECs providing the first proof-of-concept evidence that FUS+ MB can be used to enhance the permeability of large molecule therapeutics across the BBB in a human ALS in vitro model.

CONCLUSIONS

Together, this study describes the first characterisation of cellular and molecular responses of ALS iBECs to FUS+ MB and provides a fully-human platform for FUS+ MB-mediated drug delivery screening on an ALS BBB in vitro model.

Lipocalin-2 promotes breast cancer brain metastasis by enhancing tumor invasion and modulating brain microenvironment

Breast cancer is the leading cancer diagnosed in women globally, with brain metastasis emerging as a major cause of death, particularly in human epidermal growth factor receptor 2 positive and triple-negative breast cancer subtypes. Comprehensive understanding of the molecular foundations of central nervous system metastases is imperative for the evolution of efficacious treatment strategies. Lipocalin-2 (LCN2), a secreted iron transport protein with multiple functions, has been linked to the progression of breast cancer brain metastasis (BCBM). In primary tumors, LCN2 promotes the proliferation and angiogenesis of breast cancer cells, triggers the epithelial-mesenchymal transition, interacts with matrix metalloproteinase-9, thereby facilitating the reorganization of the extracellular matrix and enhancing cancer cell invasion and migration. In brain microenvironment, LCN2 undermines the blood-brain barrier and facilitates tumor seeding in the brain by modulating the behavior of key cellular components. In summary, this review meticulously examines the fuel role of LCN2 in BCBM cascade, and investigates the potential mechanisms involved. It highlights the potential of LCN2 as both a therapeutic target and biomarker, indicating that interventions targeting LCN2 may offer improved outcomes for patients afflicted with BCBM.

Low-intensity pulsed ultrasound stimulation (LIPUS) modulates microglial activation following intracortical microelectrode implantation

Microglia are important players in surveillance and repair of the brain. Implanting an electrode into the cortex activates microglia, produces an inflammatory cascade, triggers the foreign body response, and opens the blood-brain barrier. These changes can impede intracortical brain-computer interfaces performance. Using two-photon imaging of implanted microelectrodes, we test the hypothesis that low-intensity pulsed ultrasound stimulation can reduce microglia-mediated neuroinflammation following the implantation of microelectrodes. In the first week of treatment, we found that low-intensity pulsed ultrasound stimulation increased microglia migration speed by 128%, enhanced microglia expansion area by 109%, and a reduction in microglial activation by 17%, indicating improved tissue healing and surveillance. Microglial coverage of the microelectrode was reduced by 50% and astrocytic scarring by 36% resulting in an increase in recording performance at chronic time. The data indicate that low-intensity pulsed ultrasound stimulation helps reduce the foreign body response around chronic intracortical microelectrodes.

Understanding the Role of Endothelial Cells in Glioblastoma: Mechanisms and Novel Treatments

Glioblastoma is a highly aggressive neoplasm and the most common primary malignant brain tumor. Endothelial tissue plays a critical role in glioblastoma growth and progression, facilitating angiogenesis, cellular communication, and tumorigenesis. In this review, we present an up-to-date and comprehensive summary of the role of endothelial cells in glioblastomas, along with an overview of recent developments in glioblastoma therapies and tumor endothelial marker identification.

Role of Glial Cells in Neuronal Function, Mood Disorders, and Drug Addiction

Mood disorders and substance use disorder (SUD) are of immense medical and social concern. Although significant progress on neuronal involvement in mood and reward circuitries has been achieved, it is only relatively recently that the role of glia in these disorders has attracted attention. Detailed understanding of the glial functions in these devastating diseases could offer novel interventions. Here, following a brief review of circuitries involved in mood regulation and reward perception, the specific contributions of neurotrophic factors, neuroinflammation, and gut microbiota to these diseases are highlighted. In this context, the role of specific glial cells (e.g., microglia, astroglia, oligodendrocytes, and synantocytes) on phenotypic manifestation of mood disorders or SUD are emphasized. In addition, use of this knowledge in the potential development of novel therapeutics is touched upon.

Roles of Epigenetics and Glial Cells in Drug-Induced Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by severe deficits in social communication and interaction, repetitive movements, abnormal focusing on objects, or activity that can significantly affect the quality of life of the afflicted. Neuronal and glial cells have been implicated. It has a genetic component but can also be triggered by environmental factors or drugs. For example, prenatal exposure to valproic acid or acetaminophen, or ingestion of propionic acid, can increase the risk of ASD. Recently, epigenetic influences on ASD have come to the forefront of investigations on the etiology, prevention, and treatment of this disorder. Epigenetics refers to DNA modifications that alter gene expression without making any changes to the DNA sequence. Although an increasing number of pharmaceuticals and environmental chemicals are being implicated in the etiology of ASD, here, we specifically focus on the molecular influences of the abovementioned chemicals on epigenetic alterations in neuronal and glial cells and their potential connection to ASD. We conclude that a better understanding of these phenomena can lead to more effective interventions in ASD.

The Interplay between Ferroptosis and Neuroinflammation in Central Neurological Disorders

Central neurological disorders are significant contributors to morbidity, mortality, and long-term disability globally in modern society. These encompass neurodegenerative diseases, ischemic brain diseases, traumatic brain injury, epilepsy, depression, and more. The involved pathogenesis is notably intricate and diverse. Ferroptosis and neuroinflammation play pivotal roles in elucidating the causes of cognitive impairment stemming from these diseases. Given the concurrent occurrence of ferroptosis and neuroinflammation due to metabolic shifts such as iron and ROS, as well as their critical roles in central nervous disorders, the investigation into the co-regulatory mechanism of ferroptosis and neuroinflammation has emerged as a prominent area of research. This paper delves into the mechanisms of ferroptosis and neuroinflammation in central nervous disorders, along with their interrelationship. It specifically emphasizes the core molecules within the shared pathways governing ferroptosis and neuroinflammation, including SIRT1, Nrf2, NF-κB, Cox-2, iNOS/NO·, and how different immune cells and structures contribute to cognitive dysfunction through these mechanisms. Researchers' findings suggest that ferroptosis and neuroinflammation mutually promote each other and may represent key factors in the progression of central neurological disorders. A deeper comprehension of the common pathway between cellular ferroptosis and neuroinflammation holds promise for improving symptoms and prognosis related to central neurological disorders.

Nicotinic Acetylcholine Receptors in Glial Cells as Molecular Target for Parkinson's Disease

Parkinson's disease (PD) is a progressive neurodegenerative disease characterized by resting tremor, bradykinesia, rigidity, and postural instability that also includes non-motor symptoms such as mood dysregulation. Dopamine (DA) is the primary neurotransmitter involved in this disease, but cholinergic imbalance has also been implicated. Current intervention in PD is focused on replenishing central DA, which provides remarkable temporary symptomatic relief but does not address neuronal loss and the progression of the disease. It has been well established that neuronal nicotinic cholinergic receptors (nAChRs) can regulate DA release and that nicotine itself may have neuroprotective effects. Recent studies identified nAChRs in nonneuronal cell types, including glial cells, where they may regulate inflammatory responses. Given the crucial role of neuroinflammation in dopaminergic degeneration and the involvement of microglia and astrocytes in this response, glial nAChRs may provide a novel therapeutic target in the prevention and/or treatment of PD. In this review, following a brief discussion of PD, we focus on the role of glial cells and, specifically, their nAChRs in PD pathology and/or treatment.

Reprogramming astrocytes into dopaminergic neurons to restore motor dysfunction in Parkinsons disease model rats

OBJECTIVES

Parkinson's disease (PD) is a neurodegenerative disorder primarily caused by the loss of dopaminergic neurons (DA) in the brain. Since DA neurons are non-renewable, conventional therapies only alleviate symptoms without addressing the root cause. This study aims to reprogram astrocyte (AS) into DA neurons for transplantation into the brain to reconstruct damaged neural circuits and treat PD.

METHODS

Astrocytes were isolated from neonatal rat brain tissues. A lentiviral vector carrying the transcription factors nuclear receptor-related factor 1 (UNRR1) and achaete-scute family bHLH transcription factor 1 (ASCL1), named LV-NURR1-ASCL1, was constructed and used to infect cultured rat AS in vitro. Immunofluorescence, Western blotting, and reverse transcription polymerase chain reaction (RT-PCR) were employed to detect and compare the expression levels of NURR1 and ASCL1 in lentivirus-infected AS (LV group) and AS cultured in complete medium without LV-NURR1-ASCL1 (Con group). The virus-infected AS was then cultured in neuronal induction medium for 18 days. Immunofluorescence was used to detect the expression of DA markers, including tyrosine hydroxylase (TH) and forkhead box A2 (FOXA2), as well as the neuronal marker class III beta tubulin (TUJ1). To establish the PD rat model, 6-hydroxydopamine (6-OHDA) was injected into 2 sites in the medial forebrain bundle (MFB) region of the right brain in rats. The reprogrammed cells (AS-iDA) were quantified and transplanted into the right MFB region of the PD model rats using a stereotaxic instrument. Four weeks after transplantation, immunofluorescence was used to assess the survival, differentiation, and migration of AS-iDA in the brain and the expression of TH, TUJ1, and FOXA2 in the brain tissue of PD rats. Eight weeks post-transplantation, the recovery of motor function in PD rats was evaluated using the apomorphine (APO)-induced rotation test, rotarod fatigue test, and open-field test.

RESULTS

Immunofluorescence analysis showed positive expression of NURR1 and ASCL1 in AS after lentiviral infection. RT-PCR results demonstrated that the mRNA expression levels of NURR1 and ASCL1 in the LV group were significantly higher than those in the Con group, with increases of (7.483±0.706)-fold and (10.830±1.940)-fold, respectively. Western blotting analysis further confirmed that the protein expression levels of NURR1 and ASCL1 in the LV group were (2.403±0.511)-fold and (4.423±0.603)-fold higher, respectively, compared to the control group. After 18 days of directed induction culture lentivirus-infected AS (AS-iDA) displayed significant morphological changes, developing neuron-like long neurites. At this stage, AS-iDA highly expressed the neuronal marker TUJ1 as well as the DA markers TH and FOXA2. Four weeks post-transplantation, immunofluorescence on brain slices from PD rats revealed that AS-iDA survived in the transplant region, migrated to surrounding areas, and expressed TUJ1, TH, and FOXA2. At 8 weeks post-transplantation, compared to untreated PD rats, PD rats transplanted with AS-iDA exhibited significantly reduced rotational behavior in the APO-induced rotation test, increased mobility in the open-field test, and extended time on the rotarod in the fatigue test (all P<0.05).

CONCLUSIONS

Lentiviral overexpression of NURR1 and ASCL1 efficiently reprograms AS into DA neurons. Transplantation of reprogrammed DA neurons significantly improves motor function in PD rats, highlighting their potential as donor cells for the treatment of neurodegenerative diseases.