Neurotoxic reactive astrocytes are induced by activated microglia

GPR37L1 identifies spinal cord astrocytes and protects neuropathic pain after nerve injury

Astrocytes in the spinal cord dorsal horn (SDH) play a pivotal role in synaptic transmission and neuropathic pain. However, the precise classification of SDH astrocytes in health and disease remains elusive. Here, we reveal Gpr37l1 as a marker and functional regulator of spinal astrocytes. Through single-nucleus RNA sequencing, we identified Gpr37l1 as a selective G-protein-coupled receptor (GPCR) marker for spinal cord astrocytes. Notably, SDH displayed reactive astrocyte phenotypes and exacerbated neuropathic pain following nerve injury combined with Gpr37l1 deficiency. In naive animals, Gpr37l1 knockdown in SDH astrocytes induces astrogliosis and pain hypersensitivity, while Gpr37l1-/- mice fail to recover from neuropathic pain. GPR37L1 activation by maresin 1 increased astrocyte glutamate transporter 1 (GLT-1) activity and reduced spinal EPSCs and neuropathic pain. Selective overexpression of Gpr37l1 in SDH astrocytes reversed neuropathic pain and astrogliosis after nerve injury. Our findings illuminate astrocyte GPR37l1 as an essential negative regulator of pain, which protects against neuropathic pain through astrocyte signaling in SDH.

Exploring human brain development and disease using assembloids

How the human brain develops and what goes awry in neurological disorders represent two long-lasting questions in neuroscience. Owing to the limited access to primary human brain tissue, insights into these questions have been largely gained through animal models. However, there are fundamental differences between developing mouse and human brain, and neural organoids derived from human pluripotent stem cells (hPSCs) have recently emerged as a robust experimental system that mimics self-organizing and multicellular features of early human brain development. Controlled integration of multiple organoids into assembloids has begun to unravel principles of cell-cell interactions. Moreover, patient-derived or genetically engineered hPSCs provide opportunities to investigate phenotypic correlates of neurodevelopmental disorders and to develop therapeutic hypotheses. Here, we outline the advances in technologies that facilitate studies by using assembloids and summarize their applications in brain development and disease modeling. Lastly, we discuss the major roadblocks of the current system and potential solutions.

Neuroinflammation, Blood-Brain Barrier, and HIV Reservoirs in the CNS: An In-Depth Exploration of Latency Mechanisms and Emerging Therapeutic Strategies

Despite the success of antiretroviral therapy (ART) in suppressing viral replication in the blood, HIV persists in the central nervous system (CNS) and causes chronic neurocognitive impairment, a hallmark of HIV-associated neurocognitive disorders (HAND). This review looks at the complex interactions among HIV, the blood-brain barrier (BBB), neuroinflammation, and the roles of viral proteins, immune cell trafficking, and pro-inflammatory mediators in establishing and maintaining latent viral reservoirs in the CNS, particularly microglia and astrocytes. Key findings show disruption of the BBB, monocyte infiltration, and activation of CNS-resident cells by HIV proteins like Tat and gp120, contributing to the neuroinflammatory environment and neuronal damage. Advances in epigenetic regulation of latency have identified targets like histone modifications and DNA methylation, and new therapeutic strategies like latency-reversing agents (LRAs), gene editing (CRISPR/Cas9), and nanoparticle-based drug delivery also offer hope. While we have made significant progress in understanding the molecular basis of HIV persistence in the CNS, overcoming the challenges of BBB penetration and neuroinflammation is key to developing effective therapies. Further research into combination therapies and novel drug delivery systems will help improve outcomes for HAND patients and bring us closer to a functional cure for HIV.

Progranulin deficiency in the brain: the interplay between neuronal and non-neuronal cells

Heterozygous mutations in GRN gene lead to insufficient levels of the progranulin (PGRN) protein, resulting in frontotemporal dementia (FTD) with TAR DNA-binding protein 43 (TDP-43) inclusions, classified pathologically as frontotemporal lobar degeneration (FTLD-TDP). Homozygous GRN mutations are exceedingly rare and cause neuronal ceroid lipofuscinosis 11, a lysosomal storage disease with onset in young adulthood, or an FTD syndrome with late-onset manifestations. In this review, we highlight the broad spectrum of clinical phenotypes associated with PGRN deficiency, including primary progressive aphasia and behavioral variant of frontotemporal dementia. We explore these phenotypes alongside relevant rodent and in vitro human models, ranging from the induced pluripotent stem cell-derived neural progenitors, neurons, microglia, and astrocytes to genetically engineered heterotypic organoids containing both neurons and astrocytes. We summarize advantages and limitations of these models in recapitulating the main FTLD-GRN hallmarks, highlighting the role of non-cell-autonomous mechanisms in the formation of TDP-43 pathology, neuroinflammation, and neurodegeneration. Data obtained from patients' brain tissues and biofluids, in parallel with single-cell transcriptomics, demonstrate the complexity of interactions among the highly heterogeneous cellular clusters present in the brain, including neurons, astrocytes, microglia, oligodendroglia, endothelial cells, and pericytes. Emerging evidence has revealed that PGRN deficiency is associated with cell cluster-specific, often conserved, genetic and molecular phenotypes in the central nervous system. In this review, we focus on how these distinct cellular populations and their dysfunctional crosstalk contribute to neurodegeneration and neuroinflammation in FTD-GRN. Specifically, we characterize the phenotypes of lipid droplet-accumulating microglia and alterations of myelin lipid content resulting from lysosomal dysfunction caused by PGRN deficiency. Additionally, we consider how the deregulation of glia-neuron communication affects the exchange of organelles such as mitochondria, and the removal of excess toxic products such as protein aggregates, in PGRN-related neurodegeneration.

Fibrillar amyloidosis and synaptic vesicle protein expression progress jointly in the cortex of a mouse model with β-amyloid pathology

Neurodegeneration, accumulation of β-amyloid (Aβ) plaques, and neuroinflammation are the major hallmarks of Alzheimer's disease. Here, we aimed to investigate the temporal and spatial association between synaptic activity, Aβ plaque load, and neuroinflammation in an Aβ mouse model with limited neurodegeneration. 26 APPSL70 and 15 C57Bl/6 mice underwent longitudinal PET-scans with [18F]UCB-H from plaque onset to levels of strong plaque load (5.3 - 11.0 months of age) to assess the synaptic vesicle protein 2A (SV2A) expression, [18F]FBB to determine the fibrillar Aβ plaque load, and [18F]GE-180 and [18F]F-DED to assess microglial and astroglial (re)activity. Statistical parametric mapping was performed to uncover similarities between the binding patterns of all four tracers. We found a continuous increase in Aβ-PET in APPSL70 mice from 5.3 to 11.0 months of age, resulting in a significantly higher [18F]FBB PET signal in the cortex, hippocampus, and thalamus of APPSL70 mice compared to C57Bl/6 mice at 11.0 months of age. Parallel increases in SV2A-PET signals were observed in the cortex and thalamus of APPSL70 mice compared to C57Bl/6 mice. Statistical parametric mapping revealed a similar pattern of Aβ- and SV2A-PET differences (dice coefficient 53 %). Patterns of microglia activation showed stronger congruency with SV2A expression (dice coefficient 58 %) than patterns of reactive astrogliosis (dice coefficient 26 %). APPSL70 mice with limited neurodegeneration comprise a close temporal and spatial association between SV2A expression, Aβ plaque load, and microglial activation. SV2A PET imaging in APPSL70 mice may facilitate longitudinal monitoring of increased synaptic activity in the earliest phase of AD.

Exosome-shuttled miR-5121 from A2 astrocytes promotes BSCB repair after traumatic SCI by activating autophagy in vascular endothelial cells

Spinal cord injury (SCI) is a severe neurological disorder that significantly impacts patients' quality of life. Following SCI, the blood-spinal cord barrier (BSCB) is destroyed, leading to ischemia and hypoxia, which further exacerbates the imbalance in the spinal cord microenvironment. A2-type astrocytes, which arise under ischemic and hypoxic conditions, have been reported to promote SCI repair. However, the roles of exosomes derived from A2 astrocytes (A2-Exos) in SCI have not been explored. This study aims to investigate the role of A2-Exos in SCI repair, particularly in BSCB restoration, and to elucidate its potential mechanisms. GEO database analysis, western blotting, and immunofluorescence were used to detect A2 astrocyte polarization after SCI in mice. In vitro, A2 astrocytes were obtained through hypoxia induction, and A2-Exos were extracted via ultracentrifugation. An in vivo SCI model and a series of in vitro experiments demonstrated the reparative effects of A2-Exos on BSCB following SCI. Furthermore, miRNA sequencing analysis and rescue experiments confirmed the role of miRNAs in A2-Exos-mediated BSCB repair. Finally, luciferase assays and western blotting were performed to investigate the underlying mechanisms. The results showed that A2-Exos promote motor function recovery and BSCB repair in mice following SCI. In vitro, A2-Exos facilitated BSCB reconstruction and endothelial cell autophagy. miRNA sequencing identified miR-5121 as the most significantly enriched miRNA in A2-Exos, suggesting its involvement in BSCB repair and autophagy regulation. AKT2 was identified as a potential downstream target of miR-5121. Functional gain- and loss-of-function experiments further validated the miR-5121/AKT2 axis. Finally, we demonstrated that the AKT2/mTOR/p70S6K pathway may mediate the effects of miR-5121 in A2-Exos on BSCB repair.

Analysis and interpretation of inflammatory fluid markers in Alzheimer's disease: a roadmap for standardization

Growing interest in the role of the immune response in Alzheimer's Disease and related dementias (ADRD) has led to widespread use of fluid inflammatory markers in research studies. To standardize the use and interpretation of inflammatory markers in AD research, we build upon prior guidelines to develop consensus statements and recommendations to advance application and interpretation of these markers. In this roadmap paper, we propose a glossary of terms related to the immune response in the context of biomarker discovery/validation, discuss current conceptualizations of inflammatory markers in research, and recommend best practices to address key knowledge gaps. We also provide consensus principles to summarize primary conceptual, methodological, and interpretative issues facing the field: (1) a single inflammatory marker is likely insufficient to describe an entire biological cascade, and multiple markers with similar or distinct functions should be simultaneously measured in a panel; (2) association studies in humans are insufficient to infer causal relationships or mechanisms; (3) neuroinflammation displays time-dependent and disease context-dependent patterns; (4) neuroinflammatory mechanisms should not be inferred based solely on blood inflammatory marker changes; and (5) standardized reporting of CSF inflammatory marker assay validation and performance will improve incorporation of inflammatory markers into the biological AD criteria.

Experimental autoimmune encephalomyelitis pathogenesis alters along animal age: impact of S100B expression

Multiple Sclerosis (MS) is the leading inflammatory and non-traumatic cause of disability in young adults, with late-onset MS emerging in middle-aged patients often resulting in poorer treatment responses and worse prognoses. The calcium-binding protein S100B is elevated in MS patients, and its targeting has shown promise in reducing disease severity in experimental autoimmune encephalomyelitis (EAE) models. However, most studies on MS pathology have focused on young animal models, leaving a gap in understanding the effects of age and S100B ablation on disease progression throughout the lifespan. This study aimed to characterize EAE in mice of different ages, examining demyelination, inflammation, and immune responses to determine whether S100B ablation could mitigate MS pathogenesis across the lifespan. EAE was induced in six cohorts of C57BL/6 mice: young adults (3 months), older adults (6 months), and middle-aged (12 months), including corresponding S100B knockout (KO) groups, followed for 23 days. Upon sacrifice, spinal cords were assessed via immunohistochemistry and Real-Time qPCR, while splenocytes were analyzed for immune cell characterization. Results indicated a more severe disease course in 12-month-old mice, marked by increased gliosis, inflammation, and impaired microglial phagocytic activity. Notably, S100B absence reduced gliosis and inflammatory markers across all ages, with 12-month-old S100B KO mice showing increased regulatory T cells. These findings highlight the exacerbating role of age and elevated S100B in MS progression, underscoring the importance of identifying age-specific MS markers and therapeutic targets.

The anti-inflammatory drug Montelukast ameliorates cognitive deficits by rescuing the inflammatory levels in young AD animal models

Neuroinflammation precedes the clinical symptoms onset of Alzheimer's disease (AD) by decades. However, the anti-inflammatory drugs were not always effective at all stages of the disease. Here, using the fly and mouse AD models, we evaluated the effects of anti-inflammatory drugs on inflammatory-related factors and the proinflammatory cytokines at different ages of AD animals. We also performed behavioral tests to evaluate the cognitive aspects of AD. Combined with the bioinformatics analysis, we would like to exhibit a better understanding of AD. Based on the previous studies and reanalysis of published database, we found aged AD animals might better represent the inflammatory status of symptomatic AD. Our results showed that mRNA levels of antimicrobial peptides (AMPs) were highly expressed in 10-day-old AD flies, while no significant difference was observed in 40-day-old AD. In aged APP/PS1 mice (22.5 months), inflammatory-related factors NF-κB, IBA1, and the mRNA levels of proinflammatory cytokines Il-1β and Il-6 were not differentially expressed. In contrast, a significant increase was observed in 7.5-month-old APP/PS1 mice. Moreover, the anti-inflammatory drug Montelukast (MON) did not ameliorate the inflammatory and cognitive defects in 22.5-month-old aged mice but showed a rescue effect in 7.5-month-old young APP/PS1 mice. Altogether, our study demonstrates the different inflammatory status might lead to variations of anti-inflammatory drug efficacy, which helps to clarify the importance of considering the pathological stage of the disease when administering treatment.

Extracellular Vesicles Derived from FGF2-Primed Astrocytes Against Mitochondrial and Synaptic Toxicities in Parkinson's Disease

Purpose

Mitochondrial dysfunction associated with neuronal degeneration and subsequent synaptic disconnection are essential for the development of Parkinson's disease (PD). Considering that astrocytes play key roles in synaptogenesis during development, we hypothesized that fibroblast growth factor - 2 (FGF2), a key factor for astrocyte development, could reverse the toxic phenotype of reactive astrocytes, and the extracellular vesicles (EVs) derived from FGF2-primed astrocytes would enhance synaptogenesis in PD model. The present study was to test this hypothesis.

Methods

EVs isolated from FGF2-primed astrocytes (FGF2-EVs) were characterized by transmission electron microscopy and nanoparticle tracking analysis. FGF2-EVs were applied to both in vitro and in vivo models of PD. EVs derived from naïve astrocytes (CON-EV) were used as control. Mitochondrial alterations, neuronal survival, synaptogenesis, and mice behavior were subsequently evaluated by quantitative real-time polymerase chain reaction, Western-blotting, immunohistochemistry, and CatWalk gait analysis. To dissect the underlying mechanisms, proteomic analysis and small interfering RNA (siRNA) mediated gene silencing were adopted.

Results

FGF2 treatment restored the expression of neural progenitor markers and suppressed the levels of A1 astrocytic markers in MPP+ pretreated astrocytes. FGF2-EVs, in comparison with that of CON-EVs, effectively protected neurons from mitochondrial fragmentation and stimulated synaptogenesis, as evidenced by expression of Mitofusin 2 (Mfn2), postsynaptic density protein 95 (PSD-95) and synaptophysin (SYP). Proteomic analysis revealed high enrichment of neural cell adhesion molecule 1 (NCAM1) in FGF2-EVs. Knocking down NCAM1 severely influenced the expression of mitochondrial and synaptic proteins. Furthermore, delivery of FGF2-EVs significantly enhanced the survival of TH+ neurons, the levels of NCAM1 and synaptogenesis in the substantia nigra of PD mice, as well as the locomotion of PD mice.

Conclusion

EVs from FGF2-primed astrocytes are superior in protecting PD mice against mitochondrial and synaptic toxicities, possibly through NCAM1, which could be used as a therapeutic strategy for PD.

Myeloid lineage C3 induces reactive gliosis and neuronal stress during CNS inflammation

Complement component C3 mediates pathology in CNS neurodegenerative diseases. Here we use scRNAseq of sorted C3-reporter positive cells from mouse brain and optic nerve to characterize C3 producing glia in experimental autoimmune encephalomyelitis (EAE), a model in which peripheral immune cells infiltrate the CNS, causing reactive gliosis and neuro-axonal pathology. We find that C3 expression in the early inflammatory stage of EAE defines disease-associated glial subtypes characterized by increased expression of genes associated with mTOR activation and cell metabolism. This pro-inflammatory subtype is abrogated with genetic C3 depletion, a finding confirmed with proteomic analyses. In addition, early optic nerve axonal injury and retinal ganglion cell oxidative stress, but not loss of post-synaptic density protein 95, are ameliorated by selective deletion of C3 in myeloid cells. These data suggest that in addition to C3b opsonization of post synaptic proteins leading to neuronal demise, C3 activation is a contributor to reactive glia in the optic nerve.

Astrocytic RNA editing regulates the host immune response to alpha-synuclein

RNA editing is a posttranscriptional mechanism that targets changes in RNA transcripts to modulate innate immune responses. We report the role of astrocyte-specific, ADAR1-mediated RNA editing in neuroinflammation in Parkinson's disease (PD). We generated human induced pluripotent stem cell-derived astrocytes, neurons and cocultures and exposed them to small soluble alpha-synuclein aggregates. Oligomeric alpha-synuclein triggered an inflammatory glial state associated with Toll-like receptor activation, viral responses, and cytokine secretion. This reactive state resulted in loss of neurosupportive functions and the induction of neuronal toxicity. Notably, interferon response pathways were activated leading to up-regulation and isoform switching of the RNA deaminase enzyme, ADAR1. ADAR1 mediates A-to-I RNA editing, and increases in RNA editing were observed in inflammatory pathways in cells, as well as in postmortem human PD brain. Aberrant, or dysregulated, ADAR1 responses and RNA editing may lead to sustained inflammatory reactive states in astrocytes triggered by alpha-synuclein aggregation, and this may drive the neuroinflammatory cascade in Parkinson's.

Unveiling the Protective Roles of Melatonin on Glial Cells in the Battle Against Alzheimer's Disease-Insights from In Vivo and In Vitro Studies

Alzheimer's disease (AD) is a chronic, progressive neurodegenerative disorder that predominantly affects the elderly. Characterized by amyloid-beta (Aβ) plaques and neurofibrillary tangles, AD leads to memory loss, cognitive decline, and severe behavioral changes. As the most common form of dementia, AD imposes a significant global health burden, highlighting the need for interventions that address underlying disease mechanisms rather than only symptomatic treatment. Glial cells, including microglia and astrocytes, play a crucial role in AD progression by mediating neuroinflammatory responses and modulating Aβ clearance and neuronal health. Dysfunction in these cells can exacerbate neuroinflammation and neuronal damage, making glial cells an important target for therapeutic intervention. This review synthesizes findings from in vivo and in vitro studies on melatonin's effects on glial cell dysfunction in AD, emphasizing the multi-mechanistic nature of its neuroprotective properties. Recent studies highlight melatonin's potential as a therapeutic agent that addresses AD-related mechanisms through its interactions with glial cells. Melatonin has demonstrated protective effects, including reducing oxidative stress, apoptosis, and inflammation, inhibiting Aβ fibrillogenesis, and modulating amyloid precursor proteins. Additionally, its influence on glial cell activity, through melatonin receptor pathways, suggests it can alleviate neuroinflammation, a key component of AD progression. The collective evidence points to melatonin's promise as a therapeutic tool with potential roles in both preventive and adjunctive treatments for AD. However, further research is necessary to establish its efficacy and safety in clinical settings.

Single-cell transcriptomic and functional studies identify glial state changes and a role for inflammatory RIPK1 signaling in ALS pathogenesis

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by motor neuron loss. Microglia and astrocyte-driven neuroinflammation is prominent in ALS, but the cell state dynamics and pathways driving disease remain unclear. We performed single-nucleus RNA sequencing of ALS spinal cords and identified altered glial cell states, including increased expression of inflammatory and glial activation markers. Many of these signals converged on the inflammation and cell death regulator receptor-interacting protein kinase 1 (RIPK1) and the necroptotic cell death pathway. In superoxide dismutase 1 (SOD1)G93A mice, blocking RIPK1 kinase activity delayed symptom onset and motor impairment and modulated glial responses. We used human induced pluripotent stem cell (iPSC)-derived motor neuron, astrocyte, and microglia tri-cultures to identify potential biomarkers that are secreted upon RIPK1 activation in vitro and modulated by RIPK1 inhibition in the cerebrospinal fluid (CSF) of people with ALS. These data reveal ALS-enriched glial populations associated with inflammation and suggest a deleterious role for neuroinflammatory signaling in ALS pathogenesis.

Effect of microglial Pd1 on glial scar formation after spinal cord injury in mice

The crosstalk between microglia and astrocytes following spinal cord injury (SCI) greatly decides the prognosis. However, a comprehensive understanding of the molecular mechanisms by which microglia regulate astrocytic activity post-SCI is lacking. Programmed cell death protein 1 (Pdcd1, Pd1) plays a crucial role in modulating immune responses by exerting suppressive effects on microglia and peripheral immune cells within the central nervous system (CNS). Previous studies have shown the involvement of Pd1 in the pathogenesis of SCI; however, the role of microglial Pd1 in astrocytic activation and the following glial scar formation remains elusive. Here, we demonstrated that the pharmacological depletion of microglia using minocycline decreased the expression of TNF-α and IL-6 while concurrently increasing the expression of IL-10 following SCI, thereby facilitating motor function recovery in mice. We observed an increase in Pd1 expression in the injured spinal cord after SCI, with precise localization of Pd1 within microglia. Based on Pd1 knockout (KO) mice, we further revealed that Pd1 deficiency disrupted glial scar formation, leading to increased inflammation, impeded nerve regeneration, enlarged tissue damage, and compromised functional recovery following SCI. In vitro study showed that siRNA-mediated inhibition of Pd1 in microglia followed by lipopolysaccharide (LPS) treatment significantly inhibited astrocyte migration and upregulated the secretion of TNF-α and CXCL9 from microglia, indicating that microglial Pd1 regulates glial scar formation through modulating the inflammatory microenvironment. Our study gains a new mechanistic insight into how microglial Pd1 decides the fate of SCI and promotes microglial Pd1 as a promising therapeutic target for SCI.

Mitigating Cannabidiol's Non-Selective Cytotoxicity via Subcellular Organelle Targeting: Exploring Mitochondrial Targeting Potential

Cannabidiol (CBD), a phytocannabinoid from Cannabis sativa, is renowned for its nonpsychoactive properties and therapeutic potential. However, its clinical application is limited by nonselective cytotoxicity, affecting microglia, oligodendrocytes, and other cells. To address this, subcellular organelle-targeting strategies were explored to minimize off-target effects and enhance CBD's therapeutic index. Three organelle-specific conjugates targeting mitochondria, endoplasmic reticulum, and lysosomes were synthesized. Among these, the mitochondria-targeting triphenylphosphonium (TPP)-modified CBD conjugates demonstrated reduced cytotoxicity and enhanced anti-inflammatory activity. Further optimization identified a four-carbon ether chain linker (CBD-TPP-C4) that increased antineuroinflammatory activity by 3-fold and reduced cytotoxicity by 1.6-fold, compared to unmodified CBD. CBD-TPP-C4 also elevated mitochondrial ATP levels in vitro, improved mitochondrial morphology and locomotor function in Caenorhabditis elegans, and potentiated morphine analgesia in mice. These findings highlight subcellular targeting as a promising strategy to enhance CBD's safety and efficacy, paving the way for improved therapeutic applications.

Microglia heterogeneity, modeling and cell-state annotation in development and neurodegeneration

Within the CNS, microglia execute various functions associated with brain development, maintenance of homeostasis and elimination of pathogens and protein aggregates. This wide range of activities is closely associated with a plethora of cellular states, which may reciprocally influence or be influenced by their functional dynamics. Advancements in single-cell RNA sequencing have enabled a nuanced exploration of the intricate diversity of microglia, both in health and disease. Here, we review our current understanding of microglial transcriptional heterogeneity. We provide an overview of mouse and human microglial diversity encompassing aspects of development, neurodegeneration, sex and CNS regions. We offer an insight into state-of-the-art technologies and model systems that are poised to improve our understanding of microglial cell states and functions. We also provide suggestions and a tool to annotate microglial cell states on the basis of gene expression.

Characterization of Isolated Human Astrocytes from Aging Brain

Astrocytes have multiple crucial roles, including maintaining brain homeostasis and synaptic function, performing phagocytic clearance, and responding to injury and repair. It has been suggested that astrocyte performance is progressively impaired with aging, leading to imbalances in the brain's internal milieu that eventually impact neuronal function and lead to neurodegeneration. Until now, most evidence of astrocytic dysfunction in aging has come from experiments done with whole tissue homogenates, astrocytes collected by laser capture, or cell cultures derived from animal models or cell lines. In this study, we used postmortem-derived whole cells sorted with anti-GFAP antibodies to compare the unbiased, whole-transcriptomes of human astrocytes from control, older non-impaired individuals and subjects with different neurodegenerative diseases, such as Parkinson's disease (PD), Alzheimer's disease (ADD), and progressive supranuclear palsy (PSP). We found hundreds of dysregulated genes between disease and control astrocytes. In addition, we identified numerous genes shared between these common neurodegenerative disorders that are similarly dysregulated; in particular, UBC a gene for ubiquitin, which is a protein integral to cellular homeostasis and critically important in regulating function and outcomes of proteins under cellular stress, was upregulated in PSP, PD, and ADD when compared to control.

Cold aortic flush after ventricular fibrillation cardiac arrest reduces inflammatory reaction but not neuronal loss in the pig cerebral cortex

This study aims to retrospectively compare two resuscitation methods (extracorporeal cardiopulmonary resuscitation (ECPR) vs. emergency preservation and resuscitation (EPR)) by pathohistologically assessing pig brains in a ventricular fibrillation cardiac arrest (VFCA) model. In prospective studies from 2004 to 2006, swine underwent VFCA for 13 (n = 6), 15 (n = 14) or 17 (n = 6) minutes with ECPR (ECPR13, ECPR15 and ECPR17). Another 15 min VFCA group (n = 8) was resuscitated with EPR and chest compressions (EPR15 + CC). Brains of animals surviving for nine days (ECPR13 n = 4, ECPR15 n = 2, ECPR17 n = 1, EPR15 + CC n = 7) were harvested. Eight different brain regions were analyzed with the image analysis software QuPath using HE-staining, GFAP- and Iba1-immunohistochemistry. Only ECPR13 and EPR15 + CC animals were included in statistical analysis, due to low survival rates in the other groups. All VFCA samples showed significantly fewer viable neurons compared to shams, but no significant differences between ECPR13 and EPR15 + CC animals were observed. ECPR13 animals showed significantly more glial activation in all cerebral cortex regions compared to shams and in occipital, temporal and parietal cortex compared to EPR15 + CC. In conclusion, EPR + CC resulted in a significantly reduced inflammatory reaction in cerebral cortex compared to ECPR but did not influence the extent of neuronal death after VFCA.

Galangin reduces MPTP-induced dopamine neuron injury via the autophagy dependent-PI3K/AKT pathway

Introduction

Research has confirmed that Galangin can attenuate autophagy and protect dopaminergic neurons. This study aims to clarify whether Galangin attenuates dopaminergic neuron injury by regulating the PI3K/AKT pathway in Parkinson's disease (PD) model mice.

Methods

The study explores the mitigating effects of Galangin on PD processes by administering 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to induce the condition. Techniques including network analysis, transcriptomic analysis, rotarod test, enzyme-linked immunosorbent assay (ELISA), qRT-PCR, western blotting, immunohistochemistry, immunofluorescence, and hematoxylin-eosin (HE) were employed to unveil the molecular changes induced by Galangin.

Results

The network pharmacological analysis showed 301 targets related to Galangin, and 2,858 genes related to PD. Galangin treatment can improve the motor coordination of PD model mice, reduce damage to neurons in the brain, improve the antioxidant capacity and reduce the inflammatory damage of brain tissue. Additionally, Galangin suppressed mRNA expression of PD markers (IL-1β, TNF-α, IL-6, SRC and PTGS2), elevated protein levels of GSH-Px, SOD, P-PI3K, P-CREB, P-AKT, TH, BDNF and P62, while decreasing α-syn, SRC, MDA, Beclin-1 and LC3B expression. Moreover, the expression of significantly different genes in the Galangin-treated group and model group analyzed by transcriptomics was basically consistent with the qRT-PCR verification results.

Conclusion

Galangin supresses Beclin-1-dependent autophagy and upregulates the PI3K/AKT signaling pathway to attenuate the neuroinflammatory injury and improve motor coordination ability in PD mice induced by MPTP.

Gut microbiota links vitamin C supplementation to enhanced mental vitality in healthy young adults with suboptimal vitamin C status: A randomized, double-blind, placebo-controlled trial

The intricate relationship between nutrition, gut microbiome, and mental health has gained increasing attention. We aimed to determine how vitamin C supplementation improves mental vitality through the gut microbiome and associated neurological and immunological changes. We used 16S rRNA sequencing to analyze gut microbiota profiles of participants from our previous trial, in which healthy young adults (20-39 years) with inadequate serum vitamin C levels (< 50 μM) received 500 mg vitamin C or a placebo twice daily for 4 weeks (vitamin C, n = 21; placebo, n = 19). We examined whether changes in gut microbiota correlated with previously determined mental vitality indices, including Stroop test performance, work engagement, and serum brain-derived neurotrophic factor (BDNF) levels. Serum concentrations of microbial-derived molecules, cytokines, and neurotransmitters were analyzed using enzyme-linked immunosorbent assay, electrochemiluminescence-based immunoassay, or ultra-high-performance liquid chromatography-mass spectrometry. Monocyte subpopulations in peripheral blood were quantified using fluorescence-activated cell sorting analysis. Vitamin C supplementation increased the relative abundance of Bacillaceae and Anaerotruncus, while decreasing Desulfovibrio, with the Desulfovibrio reduction correlating with Stroop test performance. Moreover, participants showing a substantial Desulfovibrio reduction ("responders") demonstrated greater BDNF increases and stronger correlations between serum L-DOPA levels and work engagement scores than did non-responders. In addition, vitamin C supplementation suppressed inflammatory responses with concurrent reduction in serum lipopolysaccharide levels, and responders showed greater decreases in IL-10 levels and classical monocyte frequencies than non-responders. In conclusion, vitamin C supplementation modulates gut microbiota composition, particularly by reducing Desulfovibrio abundance, with the extent of reduction correlating with mental vitality improvements and decreased inflammation. This study provides insights into vitamin C supplementation as a critical dietary intervention, as it may modulate mental health through its influence on the gut-brain-immune axis.

Role of clonal inflammatory microglia in histiocytosis-associated neurodegeneration

Langerhans cell histiocytosis (LCH) and Erdheim-Chester disease (ECD) are clonal myeloid disorders associated with mitogen-activated protein (MAP)-kinase-activating mutations and an increased risk of neurodegeneration. We found microglial mutant clones in LCH and ECD patients, whether or not they presented with clinical symptoms of neurodegeneration, associated with microgliosis, astrocytosis, and neuronal loss, predominantly in the rhombencephalon gray nuclei. Neurological symptoms were associated with PU.1+ clone size (p = 0.0003) in patients with the longest evolution of the disease, indicating a phase of subclinical incipient neurodegeneration. Genetic barcoding analysis suggests that clones may originate from definitive or yolk sac hematopoiesis, depending on the patients. In a mouse model, disease topography was attributable to a local clonal proliferative advantage, and microglia depletion by a CSF1R-inhibitor limited neuronal loss and improved survival. These studies characterize a neurodegenerative disease associated with clonal proliferation of inflammatory microglia. The long preclinical stage represents a therapeutic window before irreversible neuronal depletion.

DL-3-n-butylphthalide inhibits astrocyte activation in the cortical penumbra of ischemia-reperfusion model rats via AKT signaling

Ischemic stroke triggers rapid activation of astrocytes, which contributes to tissue damage. Dl-3-n-butylphthalide (NBP), an independently developed compound in China for the treatment of ischemic stroke, has unclear molecular mechanisms. In this study, we established a Sprague-Dawley rat model of middle cerebral artery occlusion (MCAO) by occluding the middle cerebral artery for 1.5 h followed by reperfusion for 72 h. We assessed neurological scores, infarct volume, neuronal injury, and the expression levels of GFAP, C3, S100A10, GLT-1, p-AKT/AKT, and p-mTOR/mTOR, as well as immunofluorescence double staining of C3/S100A10 with GFAP and GLT-1 respectively. NBP significantly improved neurological function in MCAO rats, reduced infarct area, alleviated neuronal injury, inhibited A1 astrocyte polarization, promoted A2 astrocyte polarization, and upregulated GLT-1 expression. However, the AKT inhibitor (TCN) weakened NBP's regulatory effects on astrocytes and GLT-1. Finally, immunofluorescence experiments showed that GLT-1 colocalized more effectively with A2 astrocytes than with A1 astrocytes. We demonstrated that NBP reduces astrocyte activation and upregulates GLT-1 expression via the AKT/mTOR pathway, providing new insights into therapeutic strategies for ischemic stroke and valuable clues for drug design.

Non-neuronal brain biology and its relevance to animal welfare

Non-neuronal cells constitute a significant portion of brain tissue and are seen as having key roles in brain homeostasis and responses to challenges. This review illustrates how non-neuronal biology can bring new perspectives to animal welfare through understanding mechanisms that determine welfare outcomes and highlighting interventions to improve welfare. Most obvious in this respect is the largely unrecognised relevance of neuroinflammation to animal welfare which is increasingly found to have roles in determining how animals respond to challenges. We start by introducing non-neuronal cells and review their involvement in affective states and cognition often seen as core psychological elements of animal welfare. We find that the evidence for a causal involvement of glia in cognition is currently more advanced than the corresponding evidence for affective states. We propose that translational research on affective disorders could usefully apply welfare science derived approaches for assessing affective states. Using evidence from translational research, we illustrate the involvement of non-neuronal cells and neuroinflammatory processes as mechanisms modulating resilience to welfare challenges including disease, pain, and social stress. We review research on impoverished environments and environmental enrichment which suggests that environmental conditions which improve animal welfare also improve resilience to challenges through balancing pro- and anti-inflammatory non-neuronal processes. We speculate that non-neuronal biology has relevance to animal welfare beyond neuro-inflammation including facilitating positive affective states. We acknowledge the relevance of neuronal biology to animal welfare whilst proposing that non-neuronal biology provides additional and relevant insights to improve animals' lives.

Modeling Spinal Cord Injury in a Dish with Hyperosmotic Stress: Population-Specific Effects and the Modulatory Role of Mesenchymal Stromal Cell Secretome

Innovations in spinal cord injury (SCI) models are crucial for developing effective therapies. This study introduces a novel in vitro SCI model using cultures of primary mixed spinal cord cells from rat pups, featuring key spinal cord cell types. This model offers distinct advantages in terms of feasibility, reproducibility, and cost-effectiveness, requiring only basic cell culture equipment. Following hyperosmotic stress via sorbitol treatment, the model recapitulated SCI pathophysiological hallmarks, with a 65% reduction in cell viability and gradual cell death over 48 h, making it ideal for evaluating neuroprotective agents. Notably, the human adipose tissue stem cell (hASC) secretome provided significant protection: it preserved metabolic viability, reduced β amyloid precursor protein (β-APP) expression in surviving neurons, and modulated the shift in the astrocytic morphotype. A transcriptomic profile of the effect of the hASC secretome treatment showed significant functional enrichments related to cell proliferation and cycle progression pathways. In addition to supporting the use of the hASC secretome as a therapy for SCI, this study is the first to use sorbitol as a hyperosmolar stressor to recapitulate key aspects of SCI pathophysiology. Thereby, this model can be used as a promising platform for evaluating therapeutic agents targeting neuroprotection and neuroregeneration, offering outputs related to cell death, neuronal stress, and protection, as well as induction of glial reactivity.

Examination of Anti-Inflammatory Effects After Propionate Supplementation in the R6/2 Mouse Model of Huntington's Disease

Huntington's disease is a progressive, untreatable neurodegenerative disorder caused by a mutation in the Huntingtin gene. Next to neurodegeneration, altered immune activation is involved in disease progression. Since central nervous system inflammation and dysfunction of immune cells are recognized as driving characteristics, immunomodulation might represent an additional therapeutic strategy. Short-chain fatty acids were known to have immunomodulatory effects in neuroinflammatory diseases, such as multiple sclerosis. In this study, R6/2 mice were treated daily with 150 mM propionate. Survival range, body weight, and motor abilities were monitored. In striatal and cortical samples, neuronal survival was analyzed by immunofluorescence staining of NeuN-positive cells and expression levels of BDNF mRNA by real-time polymerase chain reaction. As inflammatory marker TNFα mRNA and IL-6 mRNA were quantified by rtPCR, iNOS-expressing cells were counted in immunologically stained brain slides. Microglial activation was evaluated by immunofluorescent staining of IBA1-positive cells and total IBA1 protein by Western Blot, in addition, SPI1 mRNA expression was quantified by rtPCR. Except for clasping behavior, propionate treatment did neither improve the clinical course nor mediated neuronal protection in R6/2 mice. Yet there was a mild anti-inflammatory effect in the CNS, with (i) reduction in SPI1-mRNA levels, (ii) reduced iNOS positive cells in the motor cortex, and (iii) normalized TNFα-mRNA in the motor cortex of propionate-treated R6/2 mice. Thus, Short-chain fatty acids, as an environmental factor in the diet, may slightly alleviate symptoms by down-regulating inflammatory factors in the central nervous system. However, they cannot prevent clinical disease progression or neuronal loss.

Central TYK2 inhibition identifies TYK2 as a key neuroimmune modulator

GWAS have identified tyrosine kinase 2 (TYK2) variants in multiple inflammatory disorders, specifically a protective hypomorphic TYK2 allele (P1104A) in multiple sclerosis (MS). Impaired TYK2 signaling within the central nervous system (CNS) may impart the protective effects of TYK2 P1104A allele in MS. We deployed brain-penetrant TYK2 inhibitors (cTYK2i) alongside the peripherally restricted TYK2 inhibitor (pTYK2i; BMS-986165) to untangle the contributions of central TYK2 inhibition in diverse models of neuroinflammation. While pTYK2i had little impact, cTYK2i reduced clinical score, lymphoid cell infiltration, and cytokines/chemokines in experimental autoimmune encephalomyelitis (EAE). Microglial activation was attenuated in cTYK2i-treated EAE spinal cords and circulating neurofilament light (NfL) was reduced in plasma and cerebral spinal fluid (CSF). Additionally, cTYK2i was protective in an antibody-mediated mouse model of primary progressive MS (PPMS). Finally, we demonstrate TYK2 inhibition has a robust impact on a unique subset of activated astrocytes termed Interferon-Responsive-Reactive-Astrocytes (IRRA). The data presented herein identify a key role for CNS TYK2 signaling in regulating neuroinflammation and solidify TYK2 as a potential therapeutic target for MS.

Astrocyte and oligodendrocyte pathology in Alzheimer's disease

Astrocytes and oligodendrocytes, once considered passive support cells, are now recognized as active participants in the pathogenesis of Alzheimer's disease. Emerging evidence highlights the critical role that these glial cells play in the pathological features of Alzheimer's, including neuroinflammation, excitotoxicity, synaptic dysfunction, and myelin degeneration, which contribute to neurodegeneration and cognitive decline. Here, we review the current understanding of astrocyte and oligodendrocyte pathology in Alzheimer's disease and highlight research that supports the therapeutic potential of modulating astrocyte and oligodendrocyte functions to treat Alzheimer's disease.

NLRP3 inflammasome in neuroinflammation and central nervous system diseases

Neuroinflammation plays an important role in the pathogenesis of various central nervous system (CNS) diseases. The NLRP3 inflammasome is an important intracellular multiprotein complex composed of the innate immune receptor NLRP3, the adaptor protein ASC, and the protease caspase-1. The activation of the NLRP3 inflammasome can induce pyroptosis and the release of the proinflammatory cytokines IL-1β and IL-18, thus playing a central role in immune and inflammatory responses. Recent studies have revealed that the NLRP3 inflammasome is activated in the brain to induce neuroinflammation, leading to further neuronal damage and functional impairment, and contributes to the pathological process of various neurological diseases, such as multiple sclerosis, Parkinson's disease, Alzheimer's disease, and stroke. In this review, we summarize the important role of the NLRP3 inflammasome in the pathogenesis of neuroinflammation and the pathological course of CNS diseases and discuss potential approaches to target the NLRP3 inflammasome for the treatment of CNS diseases.

Astrocytes, reactive astrogliosis, and glial scar formation in traumatic brain injury

Traumatic brain injury is a global health crisis, causing significant death and disability worldwide. Neuroinflammation that follows traumatic brain injury has serious consequences for neuronal survival and cognitive impairments, with astrocytes involved in this response. Following traumatic brain injury, astrocytes rapidly become reactive, and astrogliosis propagates from the injury core to distant brain regions. Homeostatic astroglial proteins are downregulated near the traumatic brain injury core, while pro-inflammatory astroglial genes are overexpressed. This altered gene expression is considered a pathological remodeling of astrocytes that produces serious consequences for neuronal survival and cognitive recovery. In addition, glial scar formed by reactive astrocytes is initially necessary to limit immune cell infiltration, but in the long term impedes axonal reconnection and functional recovery. Current therapeutic strategies for traumatic brain injury are focused on preventing acute complications. Statins, cannabinoids, progesterone, beta-blockers, and cerebrolysin demonstrate neuroprotective benefits but most of them have not been studied in the context of astrocytes. In this review, we discuss the cell signaling pathways activated in reactive astrocytes following traumatic brain injury and we discuss some of the potential new strategies aimed to modulate astroglial responses in traumatic brain injury, especially using cell-targeted strategies with miRNAs or lncRNA, viral vectors, and repurposed drugs.

Lipid metabolism, remodelling and intercellular transfer in the CNS

Lipid metabolism encompasses the catabolism and anabolism of lipids, and is fundamental for the maintenance of cellular homeostasis, particularly within the lipid-rich CNS. Increasing evidence further underscores the importance of lipid remodelling and transfer within and between glial cells and neurons as key orchestrators of CNS lipid homeostasis. In this Review, we summarize and discuss the complex landscape of processes involved in lipid metabolism, remodelling and intercellular transfer in the CNS. Highlighted are key pathways, including those mediating lipid (and lipid droplet) biogenesis and breakdown, lipid oxidation and phospholipid metabolism, as well as cell-cell lipid transfer mediated via lipoproteins, extracellular vesicles and tunnelling nanotubes. We further explore how the dysregulation of these pathways contributes to the onset and progression of neurodegenerative diseases, and examine the homeostatic and pathogenic impacts of environment, diet and lifestyle on CNS lipid metabolism.

Mechanisms and Therapeutic Prospects of Microglia-Astrocyte Interactions in Neuropathic Pain Following Spinal Cord Injury

Neuropathic pain is a prevalent and debilitating condition experienced by the majority of individuals with spinal cord injury (SCI). The complex pathophysiology of neuropathic pain, involving continuous activation of microglia and astrocytes, reactive gliosis, and altered neuronal plasticity, poses significant challenges for effective treatment. This review focuses on the pivotal roles of microglia and astrocytes, the two major glial cell types in the central nervous system, in the development and maintenance of neuropathic pain after SCI. We highlight the extensive bidirectional interactions between these cells, mediated by the release of inflammatory mediators, neurotransmitters, and neurotrophic factors, which contribute to the amplification of pain signaling. Understanding the microglia-astrocyte crosstalk and its impact on neuronal function is crucial for developing novel therapeutic strategies targeting neuropathic pain. In addition, this review discusses the fundamental biology, post-injury pain roles, and therapeutic prospects of microglia and astrocytes in neuropathic pain after SCI and elucidates the specific signaling pathways involved. We also speculated that the extracellular matrix (ECM) can affect the glial cells as well. Furthermore, we also mentioned potential targeted therapies, challenges, and progress in clinical trials, as well as new biomarkers and therapeutic targets. Finally, other relevant cell interactions in neuropathic pain and the role of glial cells in other neuropathic pain conditions have been discussed. This review serves as a comprehensive resource for further investigations into the microglia-astrocyte interaction and the detailed mechanisms of neuropathic pain after SCI, with the aim of improving therapeutic efficacy.

Overexpressed CD73 attenuates GSDMD-mediated astrocyte pyroptosis induced by cerebral ischemia-reperfusion injury through the A2B/NF-κB pathway

Ischemic stroke, resulting from the blockage or narrowing of cerebral vessels, causes brain tissue damage due to ischemia and hypoxia. Although reperfusion therapy is essential to restore blood flow, it may also result in reperfusion injury, causing secondary damage through mechanisms like oxidative stress, inflammation, and excitotoxicity. These effects significantly impact astrocytes, neurons, and endothelial cells, aggravating brain injury and disrupting the blood-brain barrier. CD73, an ectoenzyme that regulates adenosine production through ATP hydrolysis, plays a critical role in purinergic signaling and neuroprotection. During ischemic stroke, CD73 expression is dynamically regulated in response to ischemia and inflammation. It catalyzes the conversion of AMP to adenosine, which activates adenosine receptors to exert neuroprotective effects. Targeting the CD73-adenosine pathway presents a potential therapeutic strategy for mitigating ischemic stroke damage. Pyroptosis, a highly inflammatory form of programmed cell death mediated by inflammasomes like NLRP3 and caspases, plays a significant role in cerebral ischemia-reperfusion injury. Astrocytes, the most abundant CNS cells, contribute to both neuroprotection and injury, with pyroptosis exacerbating inflammation and brain damage. Regulating astrocyte pyroptosis is a promising therapeutic target. Our study investigates CD73's role in regulating astrocyte pyroptosis during ischemia-reperfusion injury. Using CD73 knockout mice and overexpression models, along with in vitro oxygen-glucose deprivation/reperfusion experiments, we found that CD73 overexpression reduces GSDMD-mediated astrocyte pyroptosis via the A2B/NF-κB pathway. These findings offer a novel approach to reducing neuroinflammation, protecting astrocytes, and improving outcomes in ischemic stroke.

Impacts of PI3K/protein kinase B pathway activation in reactive astrocytes: from detrimental effects to protective functions

Astrocytes are the most abundant type of glial cell in the central nervous system. Upon injury and inflammation, astrocytes become reactive and undergo morphological and functional changes. Depending on their phenotypic classification as A1 or A2, reactive astrocytes contribute to both neurotoxic and neuroprotective responses, respectively. However, this binary classification does not fully capture the diversity of astrocyte responses observed across different diseases and injuries. Transcriptomic analysis has revealed that reactive astrocytes have a complex landscape of gene expression profiles, which emphasizes the heterogeneous nature of their reactivity. Astrocytes actively participate in regulating central nervous system inflammation by interacting with microglia and other cell types, releasing cytokines, and influencing the immune response. The phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway is a central player in astrocyte reactivity and impacts various aspects of astrocyte behavior, as evidenced by in silico , in vitro , and in vivo results. In astrocytes, inflammatory cues trigger a cascade of molecular events, where nuclear factor-κB serves as a central mediator of the pro-inflammatory responses. Here, we review the heterogeneity of reactive astrocytes and the molecular mechanisms underlying their activation. We highlight the involvement of various signaling pathways that regulate astrocyte reactivity, including the PI3K/AKT/mammalian target of rapamycin (mTOR), α v β 3 integrin/PI3K/AKT/connexin 43, and Notch/PI3K/AKT pathways. While targeting the inactivation of the PI3K/AKT cellular signaling pathway to control reactive astrocytes and prevent central nervous system damage, evidence suggests that activating this pathway could also yield beneficial outcomes. This dual function of the PI3K/AKT pathway underscores its complexity in astrocyte reactivity and brain function modulation. The review emphasizes the importance of employing astrocyte-exclusive models to understand their functions accurately and these models are essential for clarifying astrocyte behavior. The findings should then be validated using in vivo models to ensure real-life relevance. The review also highlights the significance of PI3K/AKT pathway modulation in preventing central nervous system damage, although further studies are required to fully comprehend its role due to varying factors such as different cell types, astrocyte responses to inflammation, and disease contexts. Specific strategies are clearly necessary to address these variables effectively.

Baicalin ameliorates neuroinflammation by targeting TLR4/MD2 complex on microglia via PI3K/AKT/NF-κB signaling pathway

This study aims to elucidate the target and mechanism of baicalin, a clinically utilized drug, in the treatment of neuroinflammatory diseases. Neuroinflammation, characterized by the activation of glial cells and the release of various pro-inflammatory cytokines, plays a critical role in the pathogenesis of various diseases, including spinal cord injury (SCI). The remission of such diseases is significantly dependent on the improvement of inflammatory microenvironment. Toll-like receptor 4/myeloid differentiation protein 2 (TLR4/MD2) complex plays an important role in pathogen recognition and innate immune activation. baicalin, a natural flavonoid, is renowned for its potent anti-inflammatory property. In this study, we discovered that baicalin significantly reduced the activation of glial cells and the levels of pro-inflammatory cytokines at the lesion site of SCI mice, thereby mitigating demyelination and neuronal damage. By directly occupying the active pocket of TLR4/MD2 complex on microglia, baicalin inhibited PI3K/AKT/NF-κB pathway, thereby exerting its anti-inflammatory effect. These findings were corroborated in mice induced by lipopolysaccharide, a TLR4 agonist. Furthermore, baicalin indirectly altered phenotype of astrocytes by reducing secretion of TNF-α, IL-1α, and C1q levels from microglia. Our work demonstrated that baicalin effectively alleviated neuroinflammation by directly targeting microglia and indirectly modulating astrocytes phenotype. As a natural flavonoid, baicalin holds significant potential as a therapeutic candidate for diseases characterized by neuroinflammation.

Astrocyte-Derived Extracellular Vesicles Alleviate Optic Nerve Injury Through Remodeling of Retinal Microenvironmental Homeostasis

Purpose

Traumatic optic neuropathy (TON) leads to the loss of retinal ganglion cells (RGCs) and results in permanent visual impairment. Protecting and regenerating RGCs is crucial for the treatment of TON. Studies have demonstrated that astrocyte-derived extracellular vesicles (ADEVs) exhibit neuroprotective effects in models of central nervous system (CNS) injury. This study aimed to investigate whether ADEVs have a similar neuroprotective effect on RGCs in an optic nerve crush (ONC) rat model.

Methods

ADEVs were collected from primary rat astrocytes, and an ONC model was established to evaluate the effects of ADEVs on retinal structure and visual function using optical coherence tomography (OCT), hematoxylin and eosin (H&E) staining, and flash visual evoked potential (f-VEP) analysis. Immunofluorescence was used to examine RGCs and investigate reactive gliotic changes. Additionally, miRNA sequencing of ADEVs and retinal mRNA sequencing were performed to identify the potential mechanisms involved.

Results

ADEVs protected RGCs from progressive loss and improved visual function. ADEVs also significantly increased the expression of glial fibrillary acidic protein (GFAP) and modulated microglial activation. The miRNAs associated with ADEVs were targeted by neuroprotective signals, such as MAPK, PI3K-AKT, and TNF-α, and through the targeting network generated via retinal mRNA sequencing, we found that potential functional genes, such as THBS1, PAK3, and Gstm1, likely participate in microenvironmental regulation.

Conclusions

We discovered that ADEVs play a neuroprotective role in optic nerve injury. Our findings provide a new cell-free therapeutic strategy for optic neuropathy.

Glial changes in the dentate gyrus of neuronal-specific PTEN knockout mice correlate with changes in cell proliferation

Dysregulated hippocampal neurogenesis is a feature of temporal lobe epilepsy (TLE), marked by increased neuronal proliferation. The tumor suppressor gene phosphatase and tensin homolog (PTEN) regulates neuronal proliferation, and its deletion is implicated in TLE. We have previously shown that deletion of neuronal subset-specific (NS)-PTEN in mice increases the number of proliferating cells throughout the dentate gyrus, including subregions that are typically devoid of neurons but rich in glial cells, most notably the Hilus and Molecular Layer. In this study, we hypothesized that NS-PTEN knockout mice would exhibit increased numbers of microglia and astrocytes in these same dentate gyrus subregions. We performed immunohistochemistry for Iba1 (microglia) and GFAP (reactive astrocytes) on wild-type and NS-PTEN knockout mice at 4 and 10 weeks of age. Our data reveal that NS-PTEN knockout mice exhibit increased Iba1+ cell density at both ages, with some male-specific effects. Subregional analysis of the dentate gyrus showed that at 4 weeks, NS-PTEN knockout mice had greater Iba1+ cell density in the Granule Cell Layer (GCL) and Hilus, and at 10 weeks, increases were observed in the GCL, Hilus, and Molecular Layer. Additionally, we observed an increased number of microglia with an amoeboid morphology and fewer with thin, ramified processes. Contrast to Iba1+ microglia, GFAP+ reactive astrocytes were localized to the neurogenic GCL. Importantly, increases in both glial types strongly correlated with heightened cell proliferation (Ki67+ cells), as reported in our previous study, underscoring the role of glial cells in the spatial dysregulation of neurogenesis in NS-PTEN knockout mice.

Astrocyte-conditional knockout of MOB2 inhibits the phenotypic conversion of reactive astrocytes from A1 to A2 following spinal cord injury in mice

After spinal cord injury (SCI), reactive astrocytes in the injured area are triggered after spinal cord injury (SCI) and to polarize into A1 astrocytes with a proinflammatory phenotype or A2 astrocytes with an anti-inflammatory phenotype. Monopolar spindle binder 2 (MOB2) induces astrocyte stellation, maintains cell homeostasis, and promotes neurite outgrowth; however, its role in the phenotypic transformation of reactive astrocytes remains unclear. Here, we confirmed for the first time that MOB2 is associated with A1/A2 phenotypic switching in reactive astrocytes following SCI in mice. MOB2 modulated A1/A2 transformation in a primary astrocyte reactive cell model. Therefore, we constructed MOB2 conditional knockout mice (MOB2GFAP-CKO) and discovered that conditional knockout of MOB2 inhibited the conversion of reactive astrocytes from A1 to A2 and hindered spinal cord function recovery. Mechanistically, MOB2 increased the activation of PI3K-AKT signaling to promote A1/A2 transformation in vitro, whereas sc79 (an AKT activator) reversed the subtype transformation of reactive astrocytes and improved functional recovery in MOB2GFAP-CKO mice after SCI. Taken together, study provides the first insights into how MOB2 acts as a novel regulator to promote the conversion this of the reactive astrocyte phenotype from A1 to A2, showing great potential for the treatment of SCI.

Fibrinogen and Neuroinflammation in the Neurovascular Unit in Stroke

Stroke remains a leading cause of death and disability worldwide. Recent evidence suggests that stroke pathophysiology extends beyond vascular dysfunction to include complex interactions within the neurovascular unit (NVU), particularly involving fibrinogen. This blood-derived protein accumulates in the brain following blood-brain barrier (BBB) disruption and plays crucial roles in neuroinflammation and tissue repair. Through its unique structural domains, fibrinogen interacts with multiple cellular components, including astrocytes, microglia, and neural stem cells, thereby modulating inflammatory responses and neural repair mechanisms. This review examines fibrinogen's structure and its diverse functions in stroke pathophysiology, focusing on its interactions with vascular cells, glial cells, and peripheral immune cells. We also discuss emerging therapeutic strategies targeting fibrinogen-mediated pathways and the challenge of translating experimental results into effective clinical treatments.

Low Vitamin K Intake Impairs Cognition, Neurogenesis, and Elevates Neuroinflammation in C57BL/6 Mice

BACKGROUND

In addition to its important roles in blood coagulation and bone formation, vitamin K (VK) contributes to brain function. Low dietary VK intake, which is common among older adults, is associated with age-related cognitive impairment.

OBJECTIVES

To elucidate the biological mechanisms underlying VK's effects on cognition, we investigated the effects of low VK (LVK) intake on cognition in C57BL/6 mice.

METHODS

Male and female 9-mo-old C57BL/6 mice (n = 60) were fed an LVK diet or a control diet for 6 mo. Behavioral tests were performed on a subset of mice (n = 26) at 15 mo, and brain tissues were collected for follow-up analyses.

RESULTS

Menaquinone-4, the predominant VK form in the brain, was significantly lower in LVK mice compared to controls (15.6 ± 13.3 compared with 189 ± 186 pmol/g, respectively, P < 0.01). LVK mice showed reduced recognition memory in the novel object test by spending a lower percentage of time exploring the novel object compared to controls (47.45% ± 4.17 compared with 58.08% ± 3.03, P = 0.04). They also spent a significantly longer time learning the task of locating the platform in the Morris water maze test. Within the hippocampal dentate gyrus, LVK mice had a significantly lower number of proliferating cells and fewer newly generated immature neurons compared to control mice. Additionally, more activated microglia cells were identified in the LVK mice.

CONCLUSIONS

Our data indicate that LVK intake reduced menaquinone-4 concentrations in brain tissues and impaired learning- and memory-related cognitive function. This impairment may be related to the observed reduced hippocampal neurogenesis and elevated neural inflammation.

Acute exposure of perchlorate on zebrafish larvae: Neurotoxicity during development

OBJECTIVE

This study aimed to assess the acute developmental toxicity of perchlorate exposure and identify its manifestation of neurotoxicity in zebrafish (Danio rerio) model.

METHODS

Zebrafish larvae were exposed to sodium perchlorate at early developmental stages and the phenotypes of various developmental abnormalities were observed and recorded. Neurodevelopmental toxicity has been studied in particular in terms of central nervous system apoptosis, peripheral motor abnormalities, and abnormal autonomic motor behavior. Samples were processed for pathological, transcriptomic, and PCR analyses.

RESULTS

Acute exposure of zebrafish larvae to perchlorate resulted in developmental toxicity in a concentration-dependent manner. Heart rate abnormality (33 %), slow blood flow (37 %), abnormal size of liver (23 %), delayed yolk absorption (70 %), and abnormal body pigmentation (100 %) were observed in the 3.83 mg/mL group. Heart edema (10 %), heart rate abnormality (60 %), slow blood flow (67 %), abnormal size of liver (77 %), delayed yolk absorption (100 %), abnormalities in intestinal morphology (30 %), abnormal body pigmentation (100 %), and shorter body length (47 %) were observed in the 4.03 mg/mL group. Developmental neurotoxicity was characterized by brain apoptosis, damage to the central nervous system (P < 0.01) and peripheral motor neurons (P < 0.0001), and reduced autonomous motor distance (P < 0.01). Transcriptomic analysis revealed that c3a.1, c5, fga, fgb, and fgg were upregulated in the complement and coagulation cascades, and the mRNA levels of c3a.1, dusp1, slc2a6, purba, and klf9 were found upregulated in PCR.

CONCLUSION

Acute perchlorate exposure on zebrafish larvae caused various developmental toxicity in a concentration-dependent manner, notably neurotoxicity. We believed the immunological and inflammatory responses were involved.

Alpha-Synuclein Phosphomimetic Y39E and S129D Knock-In Mice Show Cytosolic Alpha-Synuclein Localization without Developing Neurodegeneration or Motor Deficits

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by motor and nonmotor symptoms. Its pathological hallmarks include the accumulation of misfolded alpha-synuclein (α-Syn) in Lewy bodies and Lewy neurites. Phosphorylation of α-Syn is a prominent feature of these inclusions, but its role in disease pathogenesis remains unclear. To identify the role of α-Syn phosphorylation in synucleinopathy, we generated two Snca knock-in (KI) mouse models carrying phosphomimetic mutations at SncaY39 or SncaS129 (SncaY39E or SncaS129D ) which manipulated epitopes phosphorylated in the PD brain. Both SncaY39E and SncaS129D KI mice displayed increased α-Syn phosphorylation, enhanced oligomer formation, and a shift of α-Syn localization from membrane-bound to cytoplasm. However, neurodegeneration in the substantia nigra was not observed up to 24 months of age. These findings demonstrate that mimicking the phosphorylation of Y39 or S129 can induce endogenous α-Syn phosphorylation. Still, a single phosphomimetic mutation alone is insufficient to induce PD-like behavior and pathology in the mouse's lifespan. Overall, our study provides a mouse model for investigating the role of phosphorylation at Y39 and S129 α-Syn epitopes in vivo.

Brain-Wide Neuroregenerative Gene Therapy Improves Cognition in a Mouse Model of Alzheimer's Disease

Alzheimer's disease (AD) is a progressive and irreversible brain disorder with extensive neuronal loss in the neocortex and hippocampus. Current therapeutic interventions focus on the early stage of AD but lack effective treatment for the late stage of AD, largely due to the inability to replenish the lost neurons and repair the broken neural circuits. In this study, by using engineered adeno-associated virus vectors that efficiently cross the blood-brain-barrier in the mouse brain, a brain-wide neuroregenerative gene therapy is developed to directly convert endogenous astrocytes into functional neurons in a mouse model of AD. It is found that ≈500 000 new neurons are regenerated and widely distributed in the cerebral cortex and hippocampus. Importantly, it is demonstrated that the converted neurons can integrate into pre-existing neural networks and improve various cognitive performances in AD mice. Chemogenetic inhibition of the converted neurons abolishes memory enhancement in AD mice, suggesting a pivotal role for the newly converted neurons in cognitive restoration. Together, brain-wide neuroregenerative gene therapy may provide a viable strategy for the treatment of AD and other brain disorders associated with massive neuronal loss.

A Neuroimmune-Oncology Microphysiological Analysis Platform (NEO-MAP) for Evaluating Astrocytic Scar Formation and Microgliosis in Glioblastoma Microenvironment

Glioblastoma multiforme (GBM) is the most aggressive type of brain tumor, characterized by its heterogeneity in cellular components, including reactive astrocytes and microglia. Since neuroimmune responses like astrogliosis and microgliosis gain recognition as vital factors in brain tumor progression, there is a growing need for clinically relevant models that assess the interactions between astrocytes, microglia, and GBM. Here, a NEuroimmune-Oncology Microphysiological Analysis Platform (NEO-MAP) is presented as a "new map" to observe astrocytic scar formation and microgliosis in response to GBM. NEO-MAP based on pathophysiological principles is designed to replicate the GBM-glia interactions, multi-phenotypic microglia activities, scar-forming astrocytes with chondroitin sulfate proteoglycans (CSPGs) in the extracellular matrix, and the biophysical characteristics of the astrocytic scar barrier. The NEO-MAP reveals that inhibiting mTORC2 in GBM promotes the proinflammatory transformation of astrocytes and enhanced astrocytic scar formation. Astrocytes that form scars prompted microglia to change from the M2 to M1 phenotype, enhancing chemotherapy sensitivity. Tissues from GBM patients show a significant correlation between reduced mTORC2 activity and increased astrogliosis, alongside a decrease in M2-polarized microgliosis, aligning with the NEO-MAP findings. Overall, the NEO-MAP is foreseen as a clinically significant tool for exploring tumor-glia interactions, opening avenues for drug development aimed at the tumor microenvironment.

SOX Genes in Spinal Cord Injury: Redefining Neural Stem Cell Regeneration Strategies

The study design is literature review. The sex-determining region Y gene (SRY)-related high mobility group box (HMG)-box (SOX) gene family has primarily been associated with neural development and sex determination and is a key component of human embryonic development. Recent studies on zebrafish models have demonstrated that the unique ability of the latter for central nervous tissue (CNS) repair following injury is largely mediated by SOX genes. Given that efforts aimed at the structural regeneration and functional restoration of neural tissue still represent a major therapeutic challenge in patients suffering CNS injury, these findings have initiated a discussion regarding the development of novel therapeutic strategies for SCI focusing on neural tissue regeneration. Spinal cord injury (SCI), in particular, represents a field that could greatly benefit from studies related to the function of the SOX genes. Neuro-informatics Laboratory, Mayo Clinic, Rochester, MN. A literature review was conducted, with a focus on SOX gene that has been described in the experimental studies of SCI. In this review, the existing evidence linking the SOX gene family to the pathophysiology of SCI is summarized, and future research steps regarding the potential implications of the SOX genes in neurological recovery following SCI are discussed, especially focusing on highlighting potential therapeutic targets. The potential implications of the latter could play a crucial role in future efforts to advance the treatment approaches to SCI.

Biological characteristics and transcriptomic profile of adipose-derived mesenchymal stem cells isolated from prion-infected murine model

BACKGROUND

Prion diseases are characterized by accumulation of misfolded host prion proteins (PrPSc) that produce aggregates in brain tissue. Mesenchymal stem cells (MSCs) have been identified as potential therapeutic candidates for prion diseases. However, it has been demonstrated that MSCs maintained and expressed PrPSc levels following inoculation, raising concerns regarding their safe and effective use in medical applications. Prion infectivity has been reported in fat tissues, thus the response of adipose-derived MSCs (AdMSCs) to prion infection needs to be fully studied.

METHODS

For this study, we analyzed the properties of AdMSCs isolated from mice infected with the ME7 scrapie strain and compared them with negative controls. We investigated morphology, viability, immunophenotyping, markers of inflammation, migration activity, and neurotrophic factors. RNA sequencing (RNA-Seq) was performed to identify transcriptome profile changes.

RESULTS

AdMSCs derived from ME7-infected mice displayed immunophenotypes similar to cells from negative controls, but they were larger with lower viability (p < 0.05). ME7 infection caused higher expression of inflammatory mediators CCL5, TNF-α, C3, and IL6 (p < 0.05 and p < 0.01) and low expression of the stem cell marker, CXCR4 (p < 0.05) which was confirmed by immunofluorescence staining. The results showed decreased migration activity and wound closure ability of AdMSCs isolated from ME7-infected mice as confirmed by Transwell migration and scratch wound assays (p < 0.05 and p < 0.001), respectively. The RNA-Seq results detected 367 differentially expressed genes between AdMSCs from ME7-infected mice and those from the negative controls, and negative regulation of locomotion, extracellular matrix (ECM) organization, collagen-containing ECM, and extracellular structure organization genes were common in AdMSCs from ME7-infected mice. Transcriptomic analysis revealed that pathways enriched in AdMSCs from ME7-infected mice included those involved in the PI3K-Akt signaling pathway, cell adhesion, protein digestion and absorption, and cytokine-cytokine receptor interactions. Interestingly, genes related to the regulation of iron storage, such as Hp and hepcidin, were upregulated in AdMSCs isolated from ME7-infected mice.

CONCLUSIONS

Based on these data, therapeutic strategies for AdMSCs in prion disease should be further investigated.

Targeting Connexin 43 in Retinal Astrocytes Promotes Neuronal Survival in Glaucomatous Injury

Astrocytes in the retina and optic nerve head play an important role in the pathogenesis of glaucoma. Astrocytes extensively express connexin 43 (Cx43), a protein that forms gap junction (GJ) channels and transmembrane unopposed hemichannels. While it is well documented that Cx43 expression is augmented in retinal injuries, the role of astrocytic Cx43 channels in glaucomatous injury is not fully understood. Here, we used a mouse model of ocular hypertension caused by intracameral microbead injections and a more severe model, optic nerve crush (ONC) injury, and assessed changes in Cx43 expression and GJ channel function. The effect of astrocyte-specific deletion of Cx43 (Cx43KO) on retinal ganglion cell (RGC) loss and visual function was also assessed. We show that the Cx43 expression is increased in retinal astrocytes at early time points and remained elevated even after sustained elevation of intraocular pressure (IOP) (~8 weeks), which paralleled an increase in astrocytic GJ coupling. Deletion of astrocytic Cx43 markedly improved the survival of RGCs by ~93% and preserved visual function as assessed by ERG and reduced numbers of activated microglial/macrophages in the glaucomatous retina. Cx43 expression was also substantially increased after ONC injury, and the absence of Cx43 in this model increased RGC survival by ~48%. These results reveal a deleterious role for Cx43 in glaucoma progression. Intravitreal injections of Gap19, a peptide that reportedly inhibits Cx43 hemichannels but not GJ channels, markedly increased RGC survival and visual function. Further studies are required to assess whether targeting Cx43 hemichannels might be useful for glaucoma treatment.

Potential roles for microglia in drug addiction: Adolescent neurodevelopment and beyond

Adolescence is a sensitive period for development of addiction-relevant brain circuits, and it is also when people typically start experimenting with drugs. Unfortunately, such substance use may cause lasting impacts on the brain, and might increase vulnerability to later-life addictions. Microglia are the brain's immune cells, but their roles in shaping neural connectivity and synaptic plasticity, especially in developmental sensitive periods like adolescence, may also contribute to addiction-related phenomena. Here, we overview how drugs of abuse impact microglia, and propose that they may play poorly-understood, but important roles in addiction vulnerability and progression.

Glial vascular Unit as a bridge between Blood-Brain Barrier and glymphatic System: Roles in sepsis-associated encephalopathy

This article underscores the Glial Vascular Unit (GVU) 's possible role in bridging the Blood-Brain Barrier (BBB) and Glymphatic System in Sepsis-associated encephalopathy (SAE). Future studies should prioritize understanding the mechanistic underpinnings of GVU dysfunction in sepsis and explore interventions aimed at modulating BBB permeability, astrocytic function, and glymphatic clearance. Understanding these complex mechanisms is crucial for developing therapeutic strategies aimed at mitigating the neurological impact of sepsis and improving outcomes for patients with SAE.