Immune cell regulation of glia during CNS injury and disease

Astrocyte heterogeneity in ischemic stroke: Molecular mechanisms and therapeutic targets

Ischemic stroke is one of the major causes of death and disability in adults, bringing a significant economic burden to the society and families. Despite significant advancements in stroke treatment, focusing solely on neurons is insufficient for improving disease progression and prognosis. Astrocytes are the most ubiquitous cells in the brain, and they undergo morphological and functional changes after brain insults, which has been known as astrocyte reactivity. Transcriptomics have shown that reactive astrocytes (RA) are heterogeneous, and they can be roughly classified into neurotoxic and neuroprotective types, thereby affecting the development of central nervous system (CNS) diseases. However, the relationship between stroke and reactive astrocyte heterogeneity has not been fully elucidated, and regulating the heterogeneity of astrocytes to play a neuroprotective role may provide a new perspective for the treatment of stroke. Here we systematically review current advancements in astrocyte heterogeneity following ischemic stroke, elucidate the molecular mechanisms underlying their activation, and further summarize promising therapeutic agents and molecular targets capable of modulating astrocyte heterogeneity.

The potential of brain organoids in addressing the heterogeneity of synucleinopathies

Synucleinopathies are a group of diseases characterized by neuronal and glial accumulation of α-synuclein (aSyn) linked with different clinical presentations, including Parkinson's disease (PD), Parkinson's disease with dementia (PDD), Dementia with Lewy Bodies (DLB) and Multiple system atrophy (MSA). Interestingly, the structure of the aSyn aggregates can vary across different synucleinopathies. Currently, it is unclear how the aSyn protein can aggregate into diverse structures and affect distinct cell types and various brain regions, leading to different clinical symptoms. Recent advances in induced pluripotent stem cells (iPSCs)-based brain organoids (BOs) technology provide an unprecedented opportunity to define the etiology of synucleinopathies in human brain cells within their three-dimensional (3D) context. In this review, we will summarize current advances in investigating the mechanisms of synucleinopathies using BOs and discuss the scope of this platform to define mechanisms underlining the selective vulnerability of cell types and brain regions in synucleinopathies.

Age-dependent glial heterogeneity and traumatic injury responses in a vertebrate brain structure

The progression of traumatic brain injury (TBI) pathology is significantly influenced by age and involves a complex interplay of glial cells. However, the influence of age on the glial dynamics and their TBI responses remains mostly unexplored. Here, we obtain a comprehensive single-cell transcriptome atlas of three major glial types under the physiological and TBI conditions across four post-embryonic life stages in the zebrafish midbrain optic tectum. We identify a library of glial subtypes and states with specific age-dependent patterns that respond distinctly to TBI. Combining the glial interactome analysis and CRISPR-Cas9-mediated gene disruption, we reveal the essential roles of dla-notch3 and cxcl12a-cxcr4b interactions in the early-larval-stage-specific unresponsiveness of radial astrocytes to TBI and the TBI-induced age-independent recruitment of microglia to injury sites, respectively. Overall, our findings provide the molecular and cellular framework of TBI-induced age-related glial dynamics in vertebrate brains.

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.

ILC2 instructs neural stem and progenitor cells to potentiate neurorepair after stroke

Stroke affects approximately 1 in 6 individuals globally and is the leading cause of adult disability, which is attributed to neuronal damage and neurological impairments. The mechanisms by which the brain tissue microenvironment supports neurogenesis and neurorepair post-stroke remain to be fully elucidated. In this study, we report that group 2 innate lymphoid cells (ILC2s) accumulate within the lesion core and subventricular zone (SVZ) during brain recovery following cerebral ischemia. Mice with ILC2 deficiency display impaired neurological scoring post-stroke. Mechanistic studies reveal that brain ILC2s enhance the proliferation of neural stem and progenitor cells (NSPCs) through the secretion of amphiregulin (Areg). Adoptive transfer of ILC2s or administration of Areg markedly improves neurological outcomes post-stroke. These findings demonstrate that ILC2s and their secreted products may represent a promising therapeutic strategy for enhancing neurorepair following brain injury.

Peripheral Blood Monocytes as Biomarkers of Neurodevelopmental Disorders: A Systematic Review and Meta-Analysis

Accumulating evidence implicates immune dysregulation and chronic inflammation in neurodevelopmental disorders (NDDs), often manifesting as abnormal alterations in peripheral blood immune cell levels. The mononuclear phagocyte system, including monocytes and microglia, has been increasingly recognized for its involvement in the pathogenesis of NDDs. However, due to inconsistent findings in the literature, whether monocytes can serve as a reliable biomarker for NDDs remains controversial. To address this issue, we conducted a systematic review and meta-analysis of studies examining monocyte counts in NDD individuals. A comprehensive search was conducted across PubMed, Web of Science, and Scopus databases. Variables extracted for analysis encompassed the author's name, year of study, sample size, patient's age, type of disease, mean, standard deviation of monocytes and sex ratio. A total of 2503 articles were found by searching the three databases. After removed duplicates and screening titles, abstracts, and full texts, 17 articles met the inclusion criteria, and 20 independent studies were included in the meta-analysis. The results indicated significantly increased monocyte counts in 5 type NDDs compared to Typical Development (TD) groups (g = 0.36, 95%CI [0.23, 0.49]). Subgroup analyses revealed no significant differences in monocyte counts across different NDD types, gender, or age. These findings suggest that aberrant alterations in monocyte counts are common in NDD cases, indicating their potential as biomarkers for these conditions. Future research should further investigate the role of monocyte in understanding the mechanisms, early detection, and clinical diagnosis of NDDs.

Intracranial AAV administration dose-dependently recruits B cells to inhibit the AAV redosing

Recombinant adeno-associated virus (rAAV) is a widely used viral vector for gene therapy. However, a limitation of AAV-mediated gene therapy is that patients are typically dosed only once. In this study, we investigated the possibility of delivering multiple rounds of AAV through intracerebral injections in the mouse brain, and discovered a dose-dependent modulation of the second administration by the first-round AAV injection in a brain-wide scale. High-dose AAV injection increased chemokines CXCL9 and CXCL10 to recruit parenchymal infiltration of lymphocytes, whereas the blood-brain-barrier was relatively intact. Brain-wide dissection discovered the likely routes of the infiltrated lymphocytes through perivascular space and ventricles. Further analysis revealed that B lymphocytes played a critical role in inhibiting the redose. Choosing the right dosage for the first injection or switching the second AAV to a different serotype provided an effective way to antagonize the first-round AAV inhibition. Together, these results suggest that mammalian brains are not immunoprivileged for AAV infection, but multiple rounds of AAV gene therapy are feasible if designed carefully with proper doses and serotypes.

Astrocyte alterations during Osmotic Demyelination Syndrome: intermediate filaments, aggresomes, proteasomes, and glycogen storages

INTRODUCTION

A murine model mimicking the human osmotic demyelination syndrome (ODS) revealed with histology demyelinated alterations in the relay posterolateral (VPL) and ventral posteromedial (VPM) thalamic nuclei 12 h and 48 h after chronic hyponatremia due to a fast reinstatement of osmolality. Abnormal expression astrocyte markers ALDHL1 and GFAP with immunohistochemistry in these ODS altered zones, prompted aims to verify in both protoplasmic and fibrillar astrocytes with ultrastructure those changes and other associated subcellular modifications.

METHOD

This ODS investigation included four groups of mice: Sham (NN; n = 13), hyponatremic (HN; n = 11), those sacrificed 12 h after a fast restoration of normal natremia (ODS12h; n = 6), and mice sacrificed 48 h afterward, or ODS48 h (n = 9). Out of those four groups of mice, with LM and ultrastructure microscopy, the thalamic zones included NN (n = 2), HN (n = 2), ODS12h (n = 3) and ODS48h (n = 3) samples. There, comparisons between astrocytes included organelles, GFAP, and glycogen content changes.

RESULTS

Thalamic ODS epicenter damages comprised both protoplasmic (PA) and fibrillar (FA) astrocyte necroses along with those of neuropil destructions and neuron Wallerian demyelinated injuries surrounded by a centrifugal region gradient revealing worse to mild destructions. Ultrastructure aspects of resilient HN and ODS12h PAs disclosed altered mitochondria and accumulations of beta- to alpha-glycogen granules that became eventually captured into phagophores as glycophagosomes in ODS48h. HN and ODS12h time lapse FAs accumulated ribonucleoproteins, cytoskeletal aggresomes, and proteasomes but distant and resilient ODS48h FAs maintained GFAP fibrils along with typical mitochondria and dispersed β-glycogen, including in their neuropil surroundings. Thus, ODS triggered astrocyte injuries that involved both post-transcriptional and post-translational modifications such that astrocytes were unable to use glycogen and metabolites due to their own mitochondria defects while accumulated stalled ribonucleoproteins, cytoskeletal aggresomes were associated with proteasomes and GFAP ablation. Resilient but distant astrocytes revealed restitution of amphibolism where typical carbohydrate storages were revealed along with GFAP, as tripartite extensions supply for restored nerve axon initial segments, neural Ranvier's junctions, and oligodendrocyte -neuron junctional contacts.

CONCLUSION

ODS caused astrocyte damage associated with adjacent neuropil destruction that included a regional demyelination caused by a loss of dispatched energetic and metabolic exchanges within the injured region, bearing proportional and collateral centrifugal injuries, which involved reactive repairs time after rebalanced osmolarity.

Adolescent exposure to micro/nanoplastics induces cognitive impairments in mice with neuronal morphological damage and multi-omic alterations

Polystyrene micro/nanoplastics (MPs/NPs) are globally recognized environmental concerns due to their widespread pollution and detrimental effects on physiological functions. However, the neurotoxic effects and underlying mechanisms of MPs/NPs on brain function in adolescents remain incompletely understood. This study investigated the effects of polystyrene MPs/NPs on neurobehavioral function in adolescent mice, utilizing multi-omic analysis and molecular biology assays to explore potential mechanisms. Following oral exposure of MPs (5 μm) or NPs (0.5 μm) at 0.5 mg/day for 4 weeks, NPs induced more severe cognitive impairment in mice than MPs, as assessed by the Morris water maze and Y-maze tests. This impairment might be associated with the neuron loss and neurogenesis inhibition caused by NPs, while dendritic spine loss mediated by MPs in the hippocampus. Furthermore, analysis of hippocampal transcriptome and Western blotting indicated the potential involvement of the PI3K/AKT pathway in NPs-induced neurotoxicity. Meanwhile, exposure to NPs induced more pronounced disruptions in the hippocampal metabolome and gut microbiota, and strong correlations were observed between changes in hippocampal metabolites and gut bacteria. This study elucidated the toxicity mechanism of MPs and NPs in inducing cognitive impairment in adolescent mice, providing insights into their toxicological impacts and potential strategies for intervention.

Dissecting the immune response of CD4+ T cells in Alzheimer's disease

The formation of amyloid-β (Aβ) plaques is a neuropathological hallmark of Alzheimer's disease (AD), however, these pathological aggregates can also be found in the brains of cognitively unimpaired elderly population. In that context, individual variations in the Aβ-specific immune response could be key factors that determine the level of Aβ-induced neuroinflammation and thus the propensity to develop AD. CD4+ T cells are the cornerstone of the immune response that coordinate the effector functions of both adaptive and innate immunity. However, despite intensive research efforts, the precise role of these cells during AD pathogenesis is still not fully elucidated. Both pathogenic and beneficial effects have been observed in various animal models of AD, as well as in humans with AD. Although this functional duality of CD4+ T cells in AD can be simply attributed to the vast phenotype heterogeneity of this cell lineage, disease stage-specific effect have also been proposed. Therefore, in this review, we summarized the current understanding of the role of CD4+ T cells in the pathophysiology of AD, from the aspect of their antigen specificity, activation, and phenotype characteristics. Such knowledge is of practical importance as it paves the way for immunomodulation as a therapeutic option for AD treatment, given that currently available therapies have not yielded satisfactory results.

Roles, Functions, and Pathological Implications of Exosomes in the Central Nervous System

Exosomes are a subset of extracellular vesicles (EVs) secreted by nearly all cell types and have emerged as a novel mechanism for intercellular communication within the central nervous system (CNS). These vesicles facilitate the transport of proteins, nucleic acids, lipids, and metabolites between neurons and glial cells, playing a pivotal role in CNS development and the maintenance of homeostasis. Current evidence indicates that exosomes from CNS cells may function as either inhibitors or enhancers in the onset and progression of neurological disorders. Furthermore, exosomes have been found to transport disease-related molecules across the blood-brain barrier, enabling their detection in peripheral blood. This distinctive property positions exosomes as promising diagnostic biomarkers for neurological conditions. Additionally, a growing body of research suggests that exosomes derived from mesenchymal stem cells exhibit reparative effects in the context of neurological disorders. This review provides a concise overview of the functions of exosomes in both physiological and pathological states, with particular emphasis on their emerging roles as potential diagnostic biomarkers and therapeutic agents in the treatment of neurological diseases.

The emerging role of the microglia triggering receptor expressed on myeloid cells (TREM) 2 in multiple sclerosis

BACKGROUND

The chronic inflammatory condition known as multiple sclerosis (MS) causes inflammation and demyelination in the central nervous system (CNS). The activation of multiple cell types, including the CNS's resident immune cells called microglia, is a component of the immunological response in MS. Recently, the triggering receptor expressed on myeloid cells (TREM) family has emerged as a crucial player in modulating microglial function and subsequent neuroinflammation. Understanding the role of TREM receptors in MS pathogenesis could provide insightful information on how to develop new therapeutic approaches.

MAIN BODY

The TREM family consists of several receptors, including TREM-1 and TREM-2, which can be expressed on both immune cells, such as myeloid cells and microglia, and non-immune cells. These receptors interact with their respective ligands and regulate signaling pathways, ultimately leading to the control of microglial activation and inflammatory reactions. TREM-2, in particular, has garnered significant interest because of its connection with MS and other neurodegenerative diseases. The activation of microglia through TREM receptors in MS is thought to influence the equilibrium between helpful and detrimental inflammatory responses. TREM receptors can promote the phagocytosis of myelin debris and remove apoptotic cells, thus contributing to tissue repair and regeneration. However, excessive or dysregulated activation of microglia mediated by TREM receptors can lead to the release of pro-inflammatory cytokines and neurotoxic factors, exacerbating neuroinflammation and neurodegeneration in MS.

CONCLUSION

The emerging role of the TREM family in demyelinating diseases highlights the importance of microglia in disease pathogenesis. Understanding the mechanisms by which TREM receptors modulate microglial function can provide valuable insights into the development of targeted therapies for these disorders. By selectively targeting TREM receptors, it may be possible to harness their beneficial effects on tissue repair while dampening their detrimental pro-inflammatory responses. Further research is warranted to elucidate the precise signaling pathways and ligand interactions involved in TREM-mediated microglial activation, which could uncover novel therapeutic avenues for treating MS and other neuroinflammatory disorders.

Evolution of the ocular immune system

The evolution of the ocular immune system should be viewed within the context of the evolution of the immune system, and indeed organisms, as a whole. Since the earliest time, the most primitive responses of single cell organisms involved molecules such as anti-microbial peptides and behaviours such as phagocytosis. Innate immunity took shape ~2.5 billion years ago while adaptive immunity and antigen specificity appeared with vertebrate evolution ~ 500 million years ago. The invention of the microscope and the germ theory of disease precipitated debate on cellular versus humoral immunity, resolved by the discovery of B and T cells. Most recently, our understanding of the microbiome and consideration of the host existing symbiotically with trillions of microbial genes (the holobiont), suggests that the immune system is a sensor of homoeostasis rather than simply a responder to pathogens. Each tissue type in multicellular organisms, such as vertebrates, has a customised response to immune challenge, with powerful reactions most evident in barrier tissues such as the skin and gut mucosa, while the eye and brain occupy the opposite extreme where responses are attenuated. The experimental background which historically led to the concept of immune privilege is discussed in this review; however, we propose that the ocular immune response should not be viewed as unique but simply an example of how the tissues variably respond in nature, more or less to the same challenge (or danger).

The Role of Microglia in Perioperative Pain and Pain Treatment: Recent Advances in Research

Microglia play a crucial role in monitoring the microenvironment of the central nervous system. Over the past decade, the role of microglia in the field of pain has gradually been unraveled. Microglia activation not only releases proinflammatory factors that enhance nociceptive signaling, but also participates in the resolving of pain. Opioids induce microglia activation, which enhances phagocytic activity and release of neurotoxic substances. Conversely, microglia activation reduces opioid efficacy and results in opioid tolerance. The application of microglia research to clinical pain management and drug development is a promising but challenging area. Microglia-targeted therapies may provide new avenues for pain management.

Alzheimer's Disease: Exploring Pathophysiological Hypotheses and the Role of Machine Learning in Drug Discovery

Alzheimer's disease (AD) is a major neurodegenerative dementia, with its complex pathophysiology challenging current treatments. Recent advancements have shifted the focus from the traditionally dominant amyloid hypothesis toward a multifactorial understanding of the disease. Emerging evidence suggests that while amyloid-beta (Aβ) accumulation is central to AD, it may not be the primary driver but rather part of a broader pathogenic process. Novel hypotheses have been proposed, including the role of tau protein abnormalities, mitochondrial dysfunction, and chronic neuroinflammation. Additionally, the gut-brain axis and epigenetic modifications have gained attention as potential contributors to AD progression. The limitations of existing therapies underscore the need for innovative strategies. This study explores the integration of machine learning (ML) in drug discovery to accelerate the identification of novel targets and drug candidates. ML offers the ability to navigate AD's complexity, enabling rapid analysis of extensive datasets and optimizing clinical trial design. The synergy between these themes presents a promising future for more effective AD treatments.

Exploring the potential of plasma and adipose mesenchymal stem cell-derived extracellular vesicles as novel platforms for neuroinflammation therapy

Persistent reactive oxygen species (ROS) and neuroinflammation contribute to the onset and progression of neurodegenerative diseases, underscoring the need for targeted therapeutic strategies to mitigate these effects. Extracellular vesicles (EVs) show promise in drug delivery due to their biocompatibility, ability to cross biological barriers, and specific interactions with cell and tissue receptors. In this study, we demonstrated that human plasma-derived EVs (pEVs) exhibit higher brain-targeting specificity, while adipose-derived mesenchymal stem cells EVs (ADMSC-EVs) offer regenerative and immunomodulatory properties. We further investigated the potential of these EVs as therapeutic carriers for brain-targeted drug delivery, using Donepezil (DNZ) as the model drug. DNZ, a cholinesterase inhibitor commonly used for Alzheimer's disease (AD), also has neuroprotective and anti-inflammatory properties. The size of EVs used ranged from 50 to 300 nm with a surface charge below -30 mV. Both formulations showed rapid cellular internalization, without toxicity, and the ability to cross the blood-brain barrier (BBB) in a zebrafish model. The have analyzed the anti-inflammatory and antioxidant actions of pEVs-DNZ and ADMSC-EVs-DNZ in the presence of lipopolysaccharide (LPS). ADMSC-EVs significantly reduced the inflammatory mediators released by HMC3 microglial cells while treatment with pEVs-DNZ and ADMSC-EVs-DNZ lowered both phagocytic activity and ROS levels in these cells. In vivo experiments using zebrafish larvae revealed that both EV formulations reduced microglial proliferation and exhibited antioxidant effects. Overall, this study highlights the potential of EVs loaded with DNZ as a novel approach for treating neuroinflammation underlying various neurodegenerative diseases.

Microglia lactylation in relation to central nervous system diseases

The development of neurodegenerative diseases is closely related to the disruption of central nervous system homeostasis. Microglia, as innate immune cells, play important roles in the maintenance of central nervous system homeostasis, injury response, and neurodegenerative diseases. Lactate has been considered a metabolic waste product, but recent studies are revealing ever more of the physiological functions of lactate. Lactylation is an important pathway in lactate function and is involved in glycolysis-related functions, macrophage polarization, neuromodulation, and angiogenesis and has also been implicated in the development of various diseases. This review provides an overview of the lactate metabolic and homeostatic regulatory processes involved in microglia lactylation, histone versus non-histone lactylation, and therapeutic approaches targeting lactate. Finally, we summarize the current research on microglia lactylation in central nervous system diseases. A deeper understanding of the metabolic regulatory mechanisms of microglia lactylation will provide more options for the treatment of central nervous system diseases.

Role of Long Non-coding RNA in Nerve Regeneration

Nerve injury can be caused by a variety of factors. It often takes a long time to repair a nerve injury and severe nerve injury is even difficult to heal. Therefore, increasing attention has focused on nerve injury and repair. Long non-coding RNA (lncRNA) is a newly discovered non-coding RNA with a wide range of biological activities. Numerous studies have shown that a variety of lncRNAs undergo changes in expression after nerve injury, indicating that lncRNAs may be involved in various biological processes of nerve repair and regeneration. Herein, we summarize the biological roles of lncRNAs in neurons, glial cells and other cells during nerve injury and regeneration, which will help lncRNAs to be better applied in nerve injury and regeneration in the future.

The m6A methyltransferase METTL3 drives neuroinflammation and neurotoxicity through stabilizing BATF mRNA in microglia

Persistent neuroinflammation and progressive neuronal loss are defining features of acute brain injury including traumatic brain injury (TBI) and cerebral stroke. Microglia, the most abundant type of brain-resident immune cells, continuously surveil the environment and play a central role in shaping the inflammatory state of the central nervous system (CNS). In the study, we discovered that the protein expression of METTL3 (a m6A methyltransferase) was upregulated in inflammatory microglia independent of increased Mettl3 gene transcription following TBI in both human and mouse subjects. Subsequently, we identified TRIP12, a HECT-domain E3 ubiquitin ligase, as a negative regulator of METTL3 protein expression by facilitating METTL3 K48-linked polyubiquitination. Importantly, selective ablation of Mettl3 inhibited microglial pathogenic activities, diminished neutrophil infiltration, rescued neuronal loss and facilitated functional recovery post-TBI. Using MeRIP-seq and CUT&Tag sequencing, we identified that METTL3 promoted the expression of Basic Leucine Zipper Transcriptional Factor ATF-Like (BATF), which in turn directly bound to a cohort of characteristic inflammatory cytokines and chemokine genes. Enhanced activities of BATF in microglia elicited TNF-dependent neurotoxicity and can also promote neutrophil recruitment through releasing CXCL2. Pharmacological inhibition of METTL3 using a BBB-penetrating drug-loaded nano-system showed satisfactory therapeutic effects in both TBI and stroke mouse models. Collectively, our findings identified METTL3-m6A-BATF axis as a potential therapeutic target for terminating detrimental neuroinflammation and progressive neuronal loss following acute brain injury. METTL3 protein is significantly up-regulated in inflammatory microglia due to the decreased proteasomal degradation mediated by TRIP12 and ERK-USP5 pathways. METTL3 stabilized BATF mRNA stability and promoted BATF expression through the m6A-IGF2BP2-dependent mechanism. Elevated expression of BATF elicits a pro-inflammatory gene program in microglia, and aggravates neuroinflammatory response including local immune responses and peripheral immune cell infiltration. Genetic deletion or pharmaceutically targeting METTL3-BATF axis suppressed microglial pro-inflammatory activities and promoted neurological recovery following TBI and stroke.

Regulation of dynamic spatiotemporal inflammation by nanomaterials in spinal cord injury

Spinal cord injury (SCI) is a common clinical condition of the central nervous system that can lead to sensory and motor impairment below the injury level or permanent loss of function in severe cases. Dynamic spatiotemporal neuroinflammation is vital to neurological recovery, which is collectively constituted by the dynamic changes in a series of inflammatory cells, including microglia, neutrophils, and astrocytes, among others. Immunomodulatory nanomaterials can readily improve the therapeutic effects and simultaneously overcome various drawbacks associated with treatment, such as the off-target side effects and loss of bioactivity of immune agents during circulation. In this review, we discuss the role of dynamic spatiotemporal inflammation in secondary injuries after SCI, elaborate on the mechanism of action and effect of existing nanomaterials in treating SCI, and summarize the mechanism(s) whereby they regulate inflammation. Finally, the challenges and prospects associated with using nanotechnology to modulate immunotherapy are discussed to provide new insights for future treatment. Deciphering the intricate spatiotemporal mechanisms of neuroinflammation in SCI requires further in-depth studies. Therefore, SCI continues to represent a formidable challenge.

STING Driving Synaptic Phagocytosis of Hippocampal Microglia/Macrophages Contributes to Cognitive Impairment in Sepsis-Associated Encephalopathy in Mice

BACKGROUND

Sepsis-associated encephalopathy (SAE) is a serious neurologic complication in septic patients with poor prognoses. There is increasing evidence that stimulator of interferon genes (STING) plays a crucial role in neuroinflammation and cognitive impairment. However, whether sepsis associated with STING changes contributes to cognitive impairment is unknown.

METHODS

Male adult mice received lipopolysaccharide (LPS) injection (a single dose of 4 mg/kg; i.p. injection) and 30 min later, they were injected with STING inhibitor C-176 (a single dose of 30 mg/kg, i.p. injection). Behavioral assessments, biochemical measurements, in vivo and ex vivo electrophysiology techniques were conducted to investigate the association between LPS-induced STING overexpression and cognitive function.

RESULTS

Cognitive impairment was associated with STING overexpression and activation of microglia/macrophages. Phagocytosis of microglia/macrophages as well as complement C1q release were increased after LPS injection, leading to abnormal pruning synapses, synaptic transmission reduction, long-term potentiation (LTP) impairment, as well as abnormal theta oscillation in the hippocampus. Notably, STING inhibitor C-176 significantly reversed these changes.

CONCLUSIONS

Sepsis-induced STING overexpression in microglia/macrophages may lead to synaptic loss, abnormal theta oscillation and LTP impairment through microglia/macrophages activation and complement C1q modulation, ultimately resulting in cognitive impairment.

Seizures Triggered by Systemic Administration of 4-Aminopyridine in Rats Lead to Acute Brain Glucose Hypometabolism, as Assessed by [18F]FDG PET Neuroimaging

4-aminopyridine (4-AP) is a non-selective blocker of voltage-dependent K+ channels used to improve walking in multiple sclerosis patients, and it may be useful in the treatment of cerebellar diseases. In animal models, 4-AP is used as a convulsant agent. When administered intrahippocampally, 4-AP induces acute local glucose hypermetabolism and significant brain damage, while i.p. administration causes less neuronal damage. This study aimed to investigate the effects of a single i.p. administration of 4-AP on acute brain glucose metabolism as well as on neuronal viability and signs of neuroinflammation 3 days after the insult. Brain glucose metabolism was evaluated by [18F]FDG PET neuroimaging. [18F]FDG uptake was analyzed based on volumes of interest (VOIs) as well as by voxel-based (SPM) analyses. The results showed that independently of the type of data analysis used (VOIs or SPM), 4-AP induced acute generalized brain glucose hypometabolism, except in the cerebellum. Furthermore, the SPM analysis normalized by the whole brain uptake revealed a significant cerebellar hypermetabolism. The neurohistochemical assays showed that 4-AP induced hippocampal astrocyte reactivity 3 days after the insult, without inducing changes in neuronal integrity or microglia-mediated neuroinflammation. Thus, acute brain glucose metabolic and neuroinflammatory profiles in response to i.p. 4-AP clearly differed from that reported for intrahippocampal administration. Finally, the results suggest that the cerebellum might be more resilient to the 4-AP-induced hypometabolism.

Neuroinflammation in Age-Related Neurodegenerative Diseases: Role of Mitochondrial Oxidative Stress

A shared hallmark of age-related neurodegenerative diseases is the chronic activation of innate immune cells, which actively contributes to the neurodegenerative process. In Alzheimer's disease, this inflammatory milieu exacerbates both amyloid and tau pathology. A similar abnormal inflammatory response has been reported in Parkinson's disease, with elevated levels of cytokines and other inflammatory intermediates derived from activated glial cells, which promote the progressive loss of nigral dopaminergic neurons. Understanding the causes that support this aberrant inflammatory response has become a topic of growing interest and research in neurodegeneration, with high translational potential. It has been postulated that the phenotypic shift of immune cells towards a proinflammatory state combined with the presence of immunogenic cell death fuels a vicious cycle in which mitochondrial dysfunction plays a central role. Mitochondria and mitochondria-generated reactive oxygen species are downstream effectors of different inflammatory signaling pathways, including inflammasomes. Dysfunctional mitochondria are also recognized as important producers of damage-associated molecular patterns, which can amplify the immune response. Here, we review the major findings highlighting the role of mitochondria as a checkpoint of neuroinflammation and immunogenic cell deaths in neurodegenerative diseases. The knowledge of these processes may help to find new druggable targets to modulate the inflammatory response.

Uncovering the dual roles of peripheral immune cells and their connections to brain cells in stroke and post-stroke stages through single-cell sequencing

Ischemic stroke is a cerebrovascular disease that affects the blood vessels and the blood supply to the brain, making it the second leading cause of death worldwide. Studies suggest that immune cells play a dual role during the inflammatory and recovery phases of stroke. However, in-depth investigations of specific cell subtypes and their differentiation trajectories remain to be elucidated. In this review, we highlight the application of single-cell RNA sequencing (scRNA-seq) for the unbiased identification of cell heterogeneity in brain and peripheral blood mononuclear cells (PBMCs) during and after a stroke. Our goal is to explore the phenotypic landscape of cells with different roles in this context. Specifically, we provide an overview of the roles, cell surface markers, immune cell-released cytokines, and intercellular interactions identified in major immune cells during and after stroke, as identified by different technologies. Additionally, we summarize the connection between immune cells in peripheral blood and the brain via their differentiation trajectories. By synthesizing the application of scRNA-seq in the combined analysis of PBMCs and brain tissue at higher sampling frequencies, we aim to unveil the dual role of peripheral immune cells, which could facilitate the development of new treatment strategies for ischemic stroke.

Spatiotemporal transcriptomic map of glial cell response in a mouse model of acute brain ischemia

The role of nonneuronal cells in the resolution of cerebral ischemia remains to be fully understood. To decode key molecular and cellular processes that occur after ischemia, we performed spatial and single-cell transcriptomic profiling of the male mouse brain during the first week of injury. Cortical gene expression was severely disrupted, defined by inflammation and cell death in the lesion core, and glial scar formation orchestrated by multiple cell types on the periphery. The glial scar was identified as a zone with intense cell-cell communication, with prominent ApoE-Trem2 signaling pathway modulating microglial activation. For each of the three major glial populations, an inflammatory-responsive state, resembling the reactive states observed in neurodegenerative contexts, was observed. The recovered spectrum of ischemia-induced oligodendrocyte states supports the emerging hypothesis that oligodendrocytes actively respond to and modulate the neuroinflammatory stimulus. The findings are further supported by analysis of other spatial transcriptomic datasets from different mouse models of ischemic brain injury. Collectively, we present a landmark transcriptomic dataset accompanied by interactive visualization that provides a comprehensive view of spatiotemporal organization of processes in the postischemic mouse brain.

Human iPSC-derived neural stem cells displaying radial glia signature exhibit long-term safety in mice

Human induced pluripotent stem cell-derived neural stem/progenitor cells (hiPSC-NSCs) hold promise for treating neurodegenerative and demyelinating disorders. However, comprehensive studies on their identity and safety remain limited. In this study, we demonstrate that hiPSC-NSCs adopt a radial glia-associated signature, sharing key epigenetic and transcriptional characteristics with human fetal neural stem cells (hfNSCs) while exhibiting divergent profiles from glioblastoma stem cells. Long-term transplantation studies in mice showed robust and stable engraftment of hiPSC-NSCs, with predominant differentiation into glial cells and no evidence of tumor formation. Additionally, we identified the Sterol Regulatory Element Binding Transcription Factor 1 (SREBF1) as a regulator of astroglial differentiation in hiPSC-NSCs. These findings provide valuable transcriptional and epigenetic reference datasets to prospectively define the maturation stage of NSCs derived from different hiPSC sources and demonstrate the long-term safety of hiPSC-NSCs, reinforcing their potential as a viable alternative to hfNSCs for clinical applications.

Constructing Electron-Rich Ru Clusters on Non-Stoichiometric Copper Hydroxide for Superior Biocatalytic ROS Scavenging to Treat Inflammatory Spinal Cord Injury

Traumatic spinal cord injury (SCI) represents a complex neuropathological challenge that significantly impacts the well-being of affected individuals. The quest for efficacious antioxidant and anti-inflammatory therapies is both a compelling necessity and a formidable challenge. Here, in this work, the innovative synthesis of electron-rich Ru clusters on non-stoichiometric copper hydroxide that contain oxygen vacancy defects (Ru/def-Cu(OH)2), which can function as a biocatalytic reactive oxygen species (ROS) scavenger for efficiently suppressing the inflammatory cascade reactions and modulating the endogenous microenvironments in SCI, is introduced. The studies reveal that the unique oxygen vacancies promote electron redistribution and amplify electron accumulation at Ru clusters, thus enhancing the catalytic activity of Ru/def-Cu(OH)2 in multielectron reactions involving oxygen-containing intermediates. These advancements endow the Ru/def-Cu(OH)2 with the capacity to mitigate ROS-mediated neuronal death and to foster a reparative microenvironment by dampening inflammatory macrophage responses, meanwhile concurrently stimulating the activity of neural stem cells, anti-inflammatory macrophages, and oligodendrocytes. Consequently, this results in a robust reparative effect on traumatic SCI. It is posited that the synthesized Ru/def-Cu(OH)2 exhibits unprecedented biocatalytic properties, offering a promising strategy to develop ROS-scavenging and anti-inflammatory materials for the management of traumatic SCI and a spectrum of other diseases associated with oxidative stress.

Cedrol attenuates acute ischemic injury through inhibition of microglia-associated neuroinflammation via ERβ-NF-κB signaling pathways

Microglia-associated neuroinflammation plays essential roles in pathology of acute stroke. Cedrol, a natural compound extracted from ginger, has been shown to confer inhibitory effects on inflammation in various diseases. However, whether Cedrol suppresses neuroinflammation and protects brains from acute ischemic injury still remains unclear. In this study, we found that Cedrol inhibited microglia activation and the production of inflammatory factors in LPS-challenged microglia and the penumbra region of middle cerebral artery occlusion (MCAO) mice. We also found that Cedrol reduced the infarct size and mNSS scores and improved acute cerebral ischemia-induced behavioral outcomes, suggesting remarked neuroprotection of Cedrol. Molecular docking analysis showed that Cedrol bound to estrogen receptor β (ERβ) with moderate-strong affinity. Intriguingly, treatment with fulvestrant, an ER blocker, abolished the anti-inflammatory effects of Cedrol. Cedrol significantly reversed the LPS- and MCAO-induced increases in phosphorylation levels of IκB and NF-κB P65 in primary microglia and MCAO mice, respectively. Additionally, Cedrol was observed to rescue LPS-induced shuttling of NF-κB P65 from cytoplasm to nuclei in primary microglia, indicating inhibitory effects of Cedrol on NF-κB signaling. These results suggest microglia associated neuroinflammation may be mediated by ERβ-NF-κB signaling pathway. Together, our study reveals that Cedrol protected brain function from acute cerebral ischemia through inhibition of microglia-associated neuroinflammation via ERβ-NF-κB signaling pathways, and Cedrol may serve as an alternative option for treatment of acute stroke injury.

Genetic association between epilepsy and gliomas: Insights from Mendelian randomization and single-cell transcriptomic analyses

BACKGROUND

Seizures are prevalent in glioma patients, especially in those with low-grade gliomas. The interaction between gliomas and epilepsy involves complex biological mechanisms that are not fully understood.

METHODS

We collected Genome-Wide Association Study data for epilepsy and gliomas, performed differential expression analysis, and conducted Gene Ontology (GO) enrichment analysis on the identified genes. Single-cell RNA sequencing data (scRNA-seq) from GSE221534 dataset in Gene Expression Omnibus (GEO) were used to analyze cell-cell interactions within glioma samples from patients with and without epilepsy.

RESULTS

Mendelian Randomization (MR) analysis revealed significant associations between genetic variants related to epilepsy and glioma risk, suggesting a potential causal relationship, especially in astrocytomas. Differential expression analysis identified epilepsy-related genes that were significantly upregulated in astrocytoma tissues compared to normal brain tissues. GO enrichment analysis indicated that these genes are involved in critical biological processes such as neurogenesis and cellular signaling. The scRNA-seq analysis showed, compared to non-epileptic samples, glioma stem cells, microglia, and NK cells are increased in the core regions of astrocytomas in epileptic patients. Additionally, intercellular communication between tumor cells and other non-tumor cells is markedly enhanced in astrocytoma samples from epileptic patients.

CONCLUSION

This study provides evidence of a genetic association between epilepsy and gliomas and elucidates the biological mechanisms through which epilepsy may influence glioma progression.

Association between Scabies Treatment and Parkinson's Disease: A Nationwide, Population-Based Study

BACKGROUND

Scabies is typically treated with scabicides like lindane, which poses a risk for acute neural toxicity. Lindane's prolonged use, particularly in agriculture, is linked to neurodegenerative diseases, including Parkinson's disease (PD), the second most common neurodegenerative disorder. This study aimed to evaluate whether scabies patients, particularly those treated with topical lindane, are at increased risk of developing PD.

METHODS

A nationwide population-based cohort study was conducted using data from Taiwan's National Health Research Institutes claims database from 2000 to 2018. The study included 27,173 patients with scabies, matched to a control group, with both groups followed for up to 18 years. The primary outcome was the incidence of newly diagnosed PD, and the hazard ratio (HR) for PD was calculated, focusing on those treated with topical lindane.

RESULTS

Among the 54,346 patients, 1639 (3.0%) were newly diagnosed with PD, with 993 (60.6%) from the scabies group and 646 (39.4%) from the control group. Scabies patients had an adjusted hazard ratio (aHR) of 1.46 (95% CI 1.32-1.63) for developing PD compared to controls. However, patients treated with topical lindane had a significantly lower aHR for PD at 0.15 (95% CI 0.12-0.19; p < 0.001), with a lower cumulative incidence of PD also observed in this group (p < 0.001).

CONCLUSIONS

Scabies patients are at a 1.46-fold increased risk of developing PD, but those treated with lindane exhibit a significantly lower risk, suggesting potential protective effects of lindane against PD.

An insight into the concept of neuroinflammation and neurodegeneration in Alzheimer's disease: targeting molecular approach Nrf2, NF-κB, and CREB

Alzheimer's disease (AD) is a most prevalent neurologic disorder characterized by cognitive dysfunction, amyloid-β (Aβ) protein accumulation, and excessive neuroinflammation. It affects various life tasks and reduces thinking, memory, capability, reasoning and orientation ability, decision, and language. The major parts responsible for these abnormalities are the cerebral cortex, amygdala, and hippocampus. Excessive inflammatory markers release, and microglial activation affect post-synaptic neurotransmission. Various mechanisms of AD pathogenesis have been explored, but still, there is a need to debate the role of NF-κB, Nrf2, inflammatory markers, CREB signaling, etc. In this review, we have briefly discussed the signaling mechanisms and function of the NF-ĸB signaling pathway, inflammatory mediators, microglia activation, and alteration of autophagy. NF-κB inhibition is a current strategy to counter neuroinflammation and neurodegeneration in the brain of individuals with AD. In clinical trials, numbers of NF-κB modulators are being examined. Recent reports revealed that molecular and cellular pathways initiate complex pathological competencies that cause AD. Moreover, this review will provide extensive knowledge of the cAMP response element binding protein (CREB) and how these nuclear proteins affect neuronal plasticity.

MicroRNA-195-5p Inhibits Intracerebral Hemorrhage-Induced Inflammatory Response and Neuron Cell Apoptosis

Intracerebral hemorrhage (ICH) is a severe condition characterized by bleeding within brain tissue. Primary brain injury in ICH results from a mechanical insult caused by blood accumulation, whereas secondary injury involves inflammation, oxidative stress, and disruption of brain physiology. miR-195-5p may participate in ICH pathology by regulating cell proliferation, oxidative stress, and inflammation. Therefore, we assessed the performance of miR-195-5p in alleviating ICH-induced secondary brain injury. ICH was established in male Sprague-Dawley rats (7 weeks old, 200-250 g) via the stereotaxic intrastriatal injection of type IV bacterial collagenase, after which miR-195-5p was administered intravenously. Neurological function was assessed using corner turn and forelimb grip strength tests. Protein expression was assessed by western blotting and ELISA. The miR-195-5p treatment significantly improved neurological function; modulated macrophage polarization by promoting anti-inflammatory marker (CD206 and Arg1) production and inhibiting pro-inflammatory marker (CD68 and iNOS) production; enhanced Akt signalling, reduced oxidative stress by increasing Sirt1 and Nrf2 levels, and attenuated inflammation by decreasing NF-κB activation; inhibited apoptosis via increased Bcl-2 and decreased cleaved caspase-3 levels; and regulated synaptic plasticity by modulating NMDAR2A, NMDAR2B, BDNF, and TrkB expression and ERK and CREB phosphorylation. In conclusion, miR-195-5p exerts neuroprotective effects in ICH by reducing inflammation and oxidative stress, inhibiting apoptosis, and restoring synaptic plasticity, ultimately restoring behavioral recovery, and represents a promising therapeutic agent that warrants clinical studies.

Comprehensive review on single-cell RNA sequencing: A new frontier in Alzheimer's disease research

Alzheimer's disease (AD) is a multifaceted neurodegenerative condition marked by gradual cognitive deterioration and the loss of neurons. While conventional bulk RNA sequencing techniques have shed light on AD pathology, they frequently obscure the cellular diversity within brain tissues. The advent of single-cell RNA sequencing (scRNA-seq) has transformed our capability to analyze the cellular composition of AD, allowing for the detection of unique cell populations, rare cell types, and gene expression alterations at an individual cell level. This review examines the use of scRNA-seq in AD research, focusing on its contributions to understanding cellular diversity, disease progression, and potential therapeutic targets. We discuss key technological innovations, data analysis techniques, and challenges associated with scRNA-seq in studying AD. Furthermore, we highlight recent studies that have utilized scRNA-seq to identify novel biomarkers, uncover disease-associated pathways, and elucidate the role of non-neuronal cells, such as microglia and astrocytes, in AD pathogenesis. By providing a comprehensive overview of advancements in scRNA-seq for unraveling cellular heterogeneity in AD, this review highlights the transformative impact of scRNA-seq on our comprehension of disease mechanisms and the creation of targeted treatments.

Experimental Type 2 diabetes and lipotoxicity-associated neuroinflammation involve mitochondrial DNA-mediated cGAS/STING axis: implication of Type-1 interferon response in cognitive impairment

Type-1 IFN (interferon)-associated innate immune response is increasingly getting attention in neurodegenerative and metabolic diseases like type 2 diabetes (T2DM). However, its significance in T2DM/lipotoxicity-induced neuroglia changes and cognitive impairment is missing. The present study aims to evaluate the involvement of cGAS (cyclic GMP-AMP synthase)-STING (stimulator of interferon gene), IRF3 (interferon regulatory factor-3), TBK (TANK binding kinase)-mediated Type-1 IFN response in the diabetic brain, and lipotoxicity (palmitate-bovine serum albumin conjugate/PA-BSA)-induced changes in cells (neuro2a and BV2). T2DM was induced in C57/BL6 mice by feeding on a high-fat diet (HFD, 60% Kcal) for 16 weeks and injecting a single dose of streptozotocin (100 mg/kg, i.p) in the 12th week. Plasma biochemical parameter analysis, neurobehavioral assessment, protein expression, and quantitative polymerase chain reaction study were carried out to decipher the hypothesis. T2DM-associated metabolic and lipotoxic stress led to mitochondrial impairment causing leakage of mtDNA to the cytoplasm further commencing cGAS activation and its downstream signaling. The diseased hippocampus and cortex showed decreased expression of synaptophysin (p < 0.01) and PSD-95 (p < 0.01, p < 0.05) with increased expression of cGAS (p < 0.001), p-STING (p < 0.001), p-STAT1 (signal transducer and activator of transcription) (p < 0.01), and IFN-β (p < 0.001) compared to normal control. The IFN-β/p-STAT1-mediated microglia activation was executed employing a conditioned media approach. C-176, a selective STING inhibitor, alleviated cGAS/p-STING/IFN-β expression and proinflammatory microglia/M1-associated markers (CD16 expression, CXCL10, TNF-α, IL-1β mRNA fold change) in the diabetic brain. The present study suggests Type-1IFN response may result in neuroglia dyshomeostasis affecting normal brain function. Alleviating STING signaling has the potential to protect T2DM-associated central ailment.

Photobiomodulation Increases M2-Type Polarization of Macrophages by Inhibiting Versican Production After Spinal Cord Injury

Spinal cord injury (SCI) is a catastrophic accidence with little effective treatment, and inflammation played an important role in that. Previous studies showed photobiomodulation (PBM) could effectively downregulate the process of inflammation with modification of macrophage polarization after SCI; however, the potential mechanism behind that is still unclear. In the presented study, we aimed to investigate the effect of PBM on the expression level of versican, a matrix molecular believed to be associated with inflammation, and tried to find the mechanism on how that could regulate the inflammation process. Using immunofluorescence technique and western blot, we found the expression level of versican is increased after injury and markedly downregulated by irradiation treatment. Using virus intrathecal injection, we found the knock-down of versican could produce the effect similar to that of PBM and might have an effect on inflammation and macrophage polarization after SCI. To further verify the deduction, we peptide the supernatant of astrocytes to induce M0, M1, and M2 macrophages. We found that the versican produced by astrocytes might have a role on the promotion of M2 macrophages to inflammatory polarization. Finally, we investigated the potential pathway in the regulation of M2 polarization with the induction of versican. This study tried to give an interpretation on the mechanism of inflammation inhibition for PBM in the perspective of matrix regulation. Our results might provide light on the inflammation regulation after SCI.

TYROBP serve as potential immune-related signature genes in the acute phase of intracerebral hemorrhage

The development of intracerebral hemorrhage (ICH) is a dynamic process and intervention during the acute phase of ICH is critical for subsequent recovery. Therefore, it is crucial to screen potential signature genes and therapeutic target genes in the acute phase of ICH. In this study, based on the results of mRNA sequencing in mouse ICH and mRNA sequencing of human ICH from online databases, top five potential signature genes after ICH, Tyrobp, Itgb2, Tlr2, Ptprc and Itgam, were screened. Quantitative PCR results showed higher mRNA expression of Tyrobp, Itgb2, Tlr2, Ptprc, and Itgam in the 1-, 3- and 5-day mouse ICH groups compared to the sham-operated group. Immune infiltration correlation analysis shows that the top-ranked signature gene, Tyrobp, is negatively correlated with M2 macrophages and plasma cells, and Western blot analysis shows higher expression of the Tyrobp protein in the 1-, 3-, and 5-day mouse ICH groups compared to the sham-operated group. Furthermore, immunohistochemistry revealed that TYROBP protein expression was significantly higher in human ICH tissues than in normal brain tissues. Our results suggest that Tyrobp is a signature gene in the acute phase of ICH and may be a potential target for the treatment of the acute phase of ICH.

A single intravenous reelin injection restores corticosterone-induced neurochemical and behavioral alterations in dams during the post-partum period

Introduction

Treatment with the synaptic plasticity protein reelin has rapid antidepressant-like effects in adult corticosterone (CORT)-induced depressed rats, whether administered repeatedly or acutely. However, these effects remain unexplored in the context of post-partum depression (PPD).

Methods

This study investigated the antidepressant-like effect of a single injection of reelin in a CORT-induced model of PPD. Long-Evans female dams received either daily subcutaneous CORT (40 mg/kg) or saline injections (controls) from the post-partum day (PD) 2 to 22, and on PD22 were treated with a single intravenous reelin (3 μg) or vehicle injection.

Results

Reelin treatment fully normalized to control levels the CORT-induced increase in Forced Swim Test (FST) immobility and the decrease in reelin-positive cells in the subgranular zone of the intermediate hippocampus. It also increased the number of oxytocin-positive cells in the paraventricular nucleus (PVN), the number of reelin-positive cells in the dorsal and ventral hippocampus, and the dendritic complexity of newborn neurons in the intermediate hippocampus, causing a partial recovery compared to controls. None of these changes were associated with fluctuations in estrogen levels measured peripherally.

Discussion

This study brings new insights into the putative antidepressant-like effect of peripherally administered reelin in an animal model of PPD. Future studies should be conducted to investigate these effects on a dose-response paradigm and to further elucidate the mechanisms underlying the antidepressant-like effects of reelin.

Meningeal Lymphatics in Central Nervous System Diseases

Since its recent discovery, the meningeal lymphatic system has reshaped our understanding of central nervous system (CNS) fluid exchange, waste clearance, immune cell trafficking, and immune privilege. Meningeal lymphatics have also been demonstrated to functionally modify the outcome of neurological disorders and their responses to treatment, including brain tumors, inflammatory diseases such as multiple sclerosis, CNS injuries, and neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. In this review, we discuss recent evidence of the contribution of meningeal lymphatics to neurological diseases, as well as the available experimental methods for manipulating meningeal lymphatics in these conditions. Finally, we also provide a discussion of the pressing questions and challenges in utilizing meningeal lymphatics as a prime target for CNS therapeutic intervention and possibly drug delivery for brain disorders.

Research on acupuncture and glial cells: A bibliometric analysis

BACKGROUND

There are a growing number of studies on the effect of acupuncture on glial cells in the central nervous system; however, there are few related bibliometric analyses in this area. Therefore, the purpose of this bibliometric study was to visualize the literature on acupuncture-regulated glial cells.

METHODS

On November 23, 2022, regular and review articles on acupuncture and glial cell-related research were retrieved from the Web of Science Core Collection database. The R package "bibliometrix" was used to summarize the main findings, count the occurrences of the top keywords, visualize the international collaboration network, and generate a 3-field plot. The VOSviewer software was used to conduct both co-authorship and co-occurrence analyses. CiteSpace was used to identify the best references and keywords with the highest citation rates.

RESULTS

Overall, 348 publications on acupuncture and glial cells were included. The publications were primarily from China, Korea, and the United States of America. The majority of publications were found in relevant journals. Apart from "acupuncture" and "glial cells," the most frequently used keywords were "neuroinflammation," "hyperalgesia," and "pain."

CONCLUSION

This bibliometric study mapped a fundamental knowledge structure comprising countries, institutions, authors, journals, and articles in the research fields of acupuncture and glial cells over the last 3 decades. These results provide a comprehensive perspective on the wider landscape of this research area.

Methylprednisolone Modulates the Tfr/Tfh ratio in EAE-Induced Neuroinflammation through the PI3K/AKT/FoxO1 and PI3K/AKT/mTOR Signalling Pathways

Methylprednisolone (MP) is a potent glucocorticoid that can effectively inhibit immune system inflammation and brain tissue damage in Multiple sclerosis (MS) patients. T follicular helper (Tfh) cells are a subpopulation of activated CD4 + T cells, while T follicular regulatory (Tfr) cells, a novel subset of Treg cells, possess specialized abilities to suppress the Tfh-GC response and inhibit antibody production. Dysregulation of either Tfh or Tfr cells has been implicated in the pathogenesis of MS. However, the molecular mechanism underlying the anti-inflammatory effects of MP therapy on experimental autoimmune encephalomyelitis (EAE), a representative model for MS, remains unclear. This study aimed to investigate the effects of MP treatment on EAE and elucidate the possible underlying molecular mechanisms involed. We evaluated the effects of MP on disease progression, CNS inflammatory cell infiltration and myelination, microglia and astrocyte activation, as well as Tfr/Tfh ratio and related molecules/inflammatory factors in EAE mice. Additionally, Western blotting was used to assess the expression of proteins associated with the PI3K/AKT pathway. Our findings demonstrated that MP treatment ameliorated clinical symptoms, inflammatory cell infiltration, and myelination. Furthermore, it reduced microglial and astrocytic activation. MP may increase the number of Tfr cells and the levels of cytokine TGF-β1, while reducing the number of Tfh cells and the levels of cytokine IL-21, as well as regulate the imbalanced Tfr/Tfh ratio in EAE mice. The PI3K/AKT/FoxO1 and PI3K/AKT/mTOR pathways were found to be involved in EAE development. However, MP treatment inhibited their activation. MP reduced neuroinflammation in EAE by regulating the balance between Tfr/Tfh cells via inhibition of the PI3K/AKT/FoxO1 and PI3K/AKT/mTOR signalling pathways.

Walnut-Derived Peptides Alleviate Learning and Memory Impairments in a Mice Model via Inhibition of Microglia Phagocytose Synapses

Microglia phagocytose synapses have an important effect on the pathogenesis of neurological disorders. Here, we investigated the neuroprotective effects of the walnut-derived peptide, TWLPLPR(TW-7), against LPS-induced cognitive deficits in mice and explored the underlying C1q-mediated microglia phagocytose synapses mechanisms in LPS-treated HT22 cells. The MWM showed that TW-7 improved the learning and memory capacity of the LPS-injured mice. Both transmission electron microscopy and immunofluorescence analysis illustrated that synaptic density and morphology were increased while associated with the decreased colocalized synapses with C1q. Immunohistochemistry and immunofluorescence demonstrated that TW-7 effectively reduced the microglia phagocytosis of synapses. Subsequently, overexpression of C1q gene plasmid was used to verify the contribution of the TW-7 via the classical complement pathway-regulated mitochondrial function-mediated microglia phagocytose synapses in LPS-treated HT22 cells. These data suggested that TW-7 improved the learning and memory capability of LPS-induced cognitively impaired mice through a mechanism associated with the classical complement pathway-mediated microglia phagocytose synapse.

Single-nucleus analysis reveals microenvironment-specific neuron and glial cell enrichment in Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) is a complicated neurodegenerative disease. Neuron-glial cell interactions are an important but not fully understood process in the progression of AD. We used bioinformatic methods to analyze single-nucleus RNA sequencing (snRNA-seq) data to investigate the cellular and molecular biological processes of AD.

METHOD

snRNA-seq data were downloaded from Gene Expression Omnibus (GEO) datasets and reprocessed to identify 240,804 single nuclei from healthy controls and patients with AD. The cellular composition of AD was further explored using Uniform Manifold Approximation and Projection (UMAP). Enrichment analysis for the functions of the DEGs was conducted and cell development trajectory analyses were used to reveal underlying cell fate decisions. iTALK was performed to identify ligand-receptor pairs among various cell types in the pathological ecological microenvironment of AD.

RESULTS

Six cell types and multiple subclusters were identified based on the snRNA-seq data. A subcluster of neuron and glial cells co-expressing lncRNA-SNHG14, myocardin-related transcription factor A (MRTFA), and MRTFB was found to be more abundant in the AD group. This subcluster was enriched in mitogen-activated protein kinase (MAPK)-, immune-, and apoptosis-related pathways. Through molecular docking, we found that lncRNA-SNHG14 may bind MRTFA and MRTFB, resulting in an interaction between neurons and glial cells.

CONCLUSIONS

The findings of this study describe a regulatory relationship between lncRNA-SNHG14, MRTFA, and MRTFB in the six main cell types of AD. This relationship may contribute to microenvironment remodeling in AD and provide a theoretical basis for a more in-depth analysis of AD.

Hyperglycemia enhances brain susceptibility to lipopolysaccharide-induced neuroinflammation via astrocyte reprogramming

Hyperglycemia has been shown to modulate the immune response of peripheral immune cells and organs, but the impact of hyperglycemia on neuroinflammation within the brain remains elusive. In the present study, we provide evidences that streptozotocin (STZ)-induced hyperglycemic condition in mice drives a phenotypic switch of brain astrocytes to a proinflammatory state, and increases brain vulnerability to mild peripheral inflammation. In particular, we found that hyperglycemia led to a significant increase in the astrocyte proliferation as determined by flow cytometric and immunohistochemical analyses of mouse brain. The increased astrocyte proliferation by hyperglycemia was reduced by Glut1 inhibitor BAY-876. Transcriptomic analysis of isolated astrocytes from Aldh1l1CreERT2;tdTomato mice revealed that peripheral STZ injection induced astrocyte reprogramming into proliferative, and proinflammatory phenotype. Additionally, STZ-induced hyperglycemic condition significantly enhanced the infiltration of circulating myeloid cells into the brain and the disruption of blood-brain barrier in response to mild lipopolysaccharide (LPS) administration. Systemic hyperglycemia did not alter the intensity and sensitivity of peripheral inflammation in mice to LPS challenge, but increased the inflammatory potential of brain microglia. In line with findings from mouse experiments, a high-glucose environment intensified the LPS-triggered production of proinflammatory molecules in primary astrocyte cultures. Furthermore, hyperglycemic mice exhibited a significant impairment in cognitive function after mild LPS administration compared to normoglycemic mice as determined by novel object recognition and Y-maze tasks. Taken together, these results demonstrate that hyperglycemia directly induces astrocyte reprogramming towards a proliferative and proinflammatory phenotype, which potentiates mild LPS-triggered inflammation within brain parenchymal regions.

Extracellular vesicles as nanotheranostic platforms for targeted neurological disorder interventions

Central Nervous System (CNS) disorders represent a profound public health challenge that affects millions of people around the world. Diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), and traumatic brain injury (TBI) exemplify the complexities and diversities that complicate their early detection and the development of effective treatments. Amid these challenges, the emergence of nanotechnology and extracellular vesicles (EVs) signals a new dawn for treating and diagnosing CNS ailments. EVs are cellularly derived lipid bilayer nanosized particles that are pivotal in intercellular communication within the CNS and have the potential to revolutionize targeted therapeutic delivery and the identification of novel biomarkers. Integrating EVs with nanotechnology amplifies their diagnostic and therapeutic capabilities, opening new avenues for managing CNS diseases. This review focuses on examining the fascinating interplay between EVs and nanotechnology in CNS theranostics. Through highlighting the remarkable advancements and unique methodologies, we aim to offer valuable perspectives on how these approaches can bring about a revolutionary change in disease management. The objective is to harness the distinctive attributes of EVs and nanotechnology to forge personalized, efficient interventions for CNS disorders, thereby providing a beacon of hope for affected individuals. In short, the confluence of EVs and nanotechnology heralds a promising frontier for targeted and impactful treatments against CNS diseases, which continue to pose significant public health challenges. By focusing on personalized and powerful diagnostic and therapeutic methods, we might improve the quality of patients.

A translocation fluorescent probe for analyzing cellular physiological parameters in neurological disease models

Neurological disorders are closely linked to the alterations in cell membrane permeability (CMP) and mitochondrial membrane potential (MMP). Changes in CMP and MMP may lead to damage and death of nerve cells, thus triggering the onset and progression of neurological diseases. Therefore, monitoring the changes of these two physiological parameters not only benefits the accurate assessment of nerve cell health status, but also enables providing key information for the diagnosis and treatment of neurological diseases. However, the simultaneous monitoring of these two cellular physiological parameters is still challenging. Herein, we design and synthesize two quinolinium-carbazole-derivated fluorescent probes (OQ and PQ). As isomers, the only difference in their chemical structures is the linking position of the carbazole unit in quinoline rings. Strikingly, such a subtle difference endows OQ and PQ with significantly different organelle-staining behaviors. PQ mainly targets at the nucleus, OQ can simultaneously stain cell membranes and mitochondria in normal cells, and performs CMP and MMP-dependent translocation from the cell membrane to mitochondria then to the nucleus, thus holding great promise as an intracellular translocation probe to image the changes of CMP and MMP. After unraveling the intrinsic mechanism of their different translocation abilities by combining experiments with molecular dynamics simulations and density functional theory calculations, we successfully used OQ to monitor the continuous changes of CMP and MMP in three neurological disease-related cell models, including oxidative stress-damaged, Parkinson's disease, and virus-infected ones. Besides providing a validated imaging tool for monitoring cellular physiological parameters, this work paves a promising route for designing intracellular translocation probes to analyze cellular physiological parameters associated with various diseases.

Potential of Neuroinflammation-Modulating Strategies in Tuberculous Meningitis: Targeting Microglia

Tuberculous meningitis (TBM) is the most severe complication of tuberculosis (TB) and is associated with high rates of disability and mortality. Mycobacterium tuberculosis (M. tb), the infectious agent of TB, disseminates from the respiratory epithelium, breaks through the blood-brain barrier, and establishes a primary infection in the meninges. Microglia are the core of the immune network in the central nervous system (CNS) and interact with glial cells and neurons to fight against harmful pathogens and maintain homeostasis in the brain through pleiotropic functions. However, M. tb directly infects microglia and resides in them as the primary host for bacillus infections. Largely, microglial activation slows disease progression. The non-productive inflammatory response that initiates the secretion of pro-inflammatory cytokines and chemokines may be neurotoxic and aggravate tissue injuries based on damages caused by M. tb. Host-directed therapy (HDT) is an emerging strategy for modulating host immune responses against diverse diseases. Recent studies have shown that HDT can control neuroinflammation in TBM and act as an adjunct therapy to antibiotic treatment. In this review, we discuss the diverse roles of microglia in TBM and potential host-directed TB therapies that target microglia to treat TBM. We also discuss the limitations of applying each HDT and suggest a course of action for the near future.

Effect of General Anesthetic Agents on Microglia

The effects of general anesthetic agents (GAAs) on microglia and their potential neurotoxicity have attracted the attention of neuroscientists. Microglia play important roles in the inflammatory process and in neuromodulation of the central nervous system. Microglia-mediated neuroinflammation is a key mechanism of neurocognitive dysfunction during the perioperative period. Microglial activation by GAAs induces anti-inflammatory and pro-inflammatory effects in microglia, suggesting that GAAs play a dual role in the mechanism of postoperative cognitive dysfunction. Understanding of the mechanisms by which GAAs regulate microglia may help to reduce the incidence of postoperative adverse effects. Here, we review the actions of GAAs on microglia and the consequent changes in microglial function. We summarize clinical and animal studies associating microglia with general anesthesia and describe how GAAs interact with neurons via microglia to further explore the mechanisms of action of GAAs in the nervous system.

Transplantation of Neural Stem Cells Loaded in an IGF-1 Bioactive Supramolecular Nanofiber Hydrogel for the Effective Treatment of Spinal Cord Injury

Spinal cord injury (SCI) leads to massive cell death, disruption, and demyelination of axons, resulting in permanent motor and sensory dysfunctions. Stem cell transplantation is a promising therapy for SCI. However, owing to the poor microenvironment that develops following SCI, the bioactivities of these grafted stem cells are limited. Cell implantation combined with biomaterial therapies is widely studied for the development of tissue engineering technology. Herein, an insulin-like growth factor-1 (IGF-1)-bioactive supramolecular nanofiber hydrogel (IGF-1 gel) is synthesized that can activate IGF-1 downstream signaling, prevent the apoptosis of neural stem cells (NSCs), improve their proliferation, and induce their differentiation into neurons and oligodendrocytes. Moreover, implantation of NSCs carried out with IGF-1 gels promotes neurite outgrowth and myelin sheath regeneration at lesion sites following SCI. In addition, IGF-1 gels can enrich extracellular vesicles (EVs) derived from NSCs or from nerve cells differentiated from these NSCs via miRNAs related to axonal regeneration and remyelination, even in an inflammatory environment. These EVs are taken up by autologous endogenous NSCs and regulate their differentiation. This study provides adequate evidence that combined treatment with NSCs and IGF-1 gels is a potential therapeutic strategy for treating SCI.

The major histocompatibility complex participates in Parkinson's disease

Parkinson's disease (PD) is a common neurodegenerative disease characterized by progressive loss of dopaminergic neurons in the substantia nigra and the aggregation of alpha-synuclein (α-syn). The central nervous system (CNS) has previously been considered as an immune-privileged area. However, studies have shown that the immune responses are involved in PD. The major histocompatibility complex (MHC) presents antigens from antigen-presenting cells (APCs) to T lymphocytes, immune responses will be induced. MHCs are expressed in microglia, astrocytes, and dopaminergic neurons. Single nucleotide polymorphisms in MHC are related to the risk of PD. The aggregated α-syn triggers the expression of MHCs by activating glia cells. CD4+ and CD8+ T lymphocytes responses and microglia activation are detected in brains of PD patients. In addiction immune responses further increase blood-brain barrier (BBB) permeability and T cell infiltration in PD. Thus, MHCs are involved in PD through participating in immune and inflammatory responses.

Disease phenotypic screening in neuron-glia cocultures identifies blockers of inflammatory neurodegeneration

Neuropathology is often mediated by interactions between neurons and glia that cannot be modeled by monocultures. However, cocultures are difficult to use and analyze for high-content screening. Here, we perform compound screening using primary neuron-glia cultures to model inflammatory neurodegeneration, live-cell stains, and automated classification of neurons, astrocytes or microglia using open-source software. Out of 227 compounds with known bioactivities, 29 protected against lipopolysaccharide-induced neuronal loss, including drugs affecting adrenergic, steroid, inflammatory and MAP kinase signaling. The screen also identified physiological compounds, such as noradrenaline and progesterone, that protected and identified neurotoxic compounds, such as a TLR7 agonist, that induced microglial proliferation. Most compounds used here have not been tested in a neuron-glia coculture neurodegeneration assay previously. Thus, combining a complex cellular disease model with high-content screening of known compounds and automated image analysis allows identification of important biology, as well as potential targets and drugs for treatment.