Astrocyte Crosstalk in CNS Inflammation

Spatial transcriptomics combined with single-nucleus RNA sequencing reveals glial cell heterogeneity in the human spinal cord

JOURNAL/nrgr/04.03/01300535-202511000-00032/figure1/v/2024-12-20T164640Z/r/image-tiff Glial cells play crucial roles in regulating physiological and pathological functions, including sensation, the response to infection and acute injury, and chronic neurodegenerative disorders. Glial cells include astrocytes, microglia, and oligodendrocytes in the central nervous system, and satellite glial cells and Schwann cells in the peripheral nervous system. Despite the greater understanding of glial cell types and functional heterogeneity achieved through single-cell and single-nucleus RNA sequencing in animal models, few studies have investigated the transcriptomic profiles of glial cells in the human spinal cord. Here, we used high-throughput single-nucleus RNA sequencing and spatial transcriptomics to map the cellular and molecular heterogeneity of astrocytes, microglia, and oligodendrocytes in the human spinal cord. To explore the conservation and divergence across species, we compared these findings with those from mice. In the human spinal cord, astrocytes, microglia, and oligodendrocytes were each divided into six distinct transcriptomic subclusters. In the mouse spinal cord, astrocytes, microglia, and oligodendrocytes were divided into five, four, and five distinct transcriptomic subclusters, respectively. The comparative results revealed substantial heterogeneity in all glial cell types between humans and mice. Additionally, we detected sex differences in gene expression in human spinal cord glial cells. Specifically, in all astrocyte subtypes, the levels of NEAT1 and CHI3L1 were higher in males than in females, whereas the levels of CST3 were lower in males than in females. In all microglial subtypes, all differentially expressed genes were located on the sex chromosomes. In addition to sex-specific gene differences, the levels of MT-ND4 , MT2A , MT-ATP6 , MT-CO3 , MT-ND2 , MT-ND3 , and MT-CO2 in all spinal cord oligodendrocyte subtypes were higher in females than in males. Collectively, the present dataset extensively characterizes glial cell heterogeneity and offers a valuable resource for exploring the cellular basis of spinal cord-related illnesses, including chronic pain, amyotrophic lateral sclerosis, and multiple sclerosis.

Integrating scRNA-seq to explore offspring neurodevelopmental toxicity induced by Cyfluthrin exposure during pregnancy: A fate decision for NSCs

Cyfluthrin is a widely used insecticide, and studies have shown that its exposure during pregnancy is associated with neurobehavioral abnormalities in offspring, but the mechanism of toxicity is unknown. In this study, we observed the neurodevelopmental toxicity of Cyfluthrin in rat offspring of different ages due to pregnancy exposure, which manifested a series of impairments such as persistent cognitive impairment, neuronal loss in hippocampal tissues, synaptic damage, and altered expression of neurodevelopmental-related factors. Hippocampal scRNA-seq in neonatal rats showed specific cellular responses to prenatal Cyfluthrin exposure. Through DEG intergroup difference analysis, intercellular communication analysis, and mimetic timing analysis, we found that the change in the fate of neural stem cells - alterations in differentiation direction, proliferation, and apoptosis levels - was the main cause of the offspring's developmental toxicity induced by prenatal Cyfluthrin exposure. This inference was verified by our in - vivo and ex - vivo experiments. Our study first constructed a single - cell atlas of the offspring's brain hippocampus exposed to Cyfluthrin during pregnancy. It warns about pesticide intake during pregnancy and nursing in women and provides a theoretical basis for neurodevelopmental toxicity from early - life exposure to environmental pollutants.

Contributions of Genetic Variation in Astrocytes to Cell and Molecular Mechanisms of Risk and Resilience to Late-Onset Alzheimer's Disease

Reactive astrocytes are associated with Alzheimer's disease (AD), and several AD genetic risk variants are associated with genes highly expressed in astrocytes. However, the contribution of genetic risk within astrocytes to cellular processes relevant to the pathogenesis of AD remains ill-defined. Here, we present a resource for studying AD genetic risk in astrocytes using a large collection of induced pluripotent stem cell (iPSC) lines from deeply phenotyped individuals with a range of neuropathological and cognitive outcomes. IPSC lines from 44 individuals were differentiated into astrocytes followed by unbiased molecular profiling using RNA sequencing and tandem mass tag-mass spectrometry. We demonstrate the utility of this resource in examining gene- and pathway-level associations with clinical and neuropathological traits, as well as in analyzing genetic risk and resilience factors through parallel analyses of iPSC-astrocytes and brain tissue from the same individuals. Our analyses reveal that genes and pathways altered in iPSC-derived astrocytes from individuals with AD are concordantly dysregulated in AD brain tissue. This includes increased levels of prefoldin proteins, extracellular matrix factors, COPI-mediated trafficking components and reduced levels of proteins involved in cellular respiration and fatty acid oxidation. Additionally, iPSC-derived astrocytes from individuals resilient to high AD neuropathology show elevated basal levels of interferon response proteins and increased secretion of interferon gamma. Correspondingly, higher polygenic risk scores for AD are associated with lower levels of interferon response proteins in astrocytes. This study establishes an experimental system that integrates genetic information with a matched iPSC lines and brain tissue data from a large cohort of individuals to identify genetic contributions to molecular pathways affecting AD risk and resilience.

Microglia activation orchestrates CXCL10-mediated CD8+ T cell recruitment to promote aging-related white matter degeneration

Aging is the major risk factor for neurodegeneration and is associated with structural and functional alterations in white matter. Myelin is particularly vulnerable to aging, resulting in white matter-associated microglia activation. Here we used pharmacological and genetic approaches to investigate microglial functions related to aging-associated changes in myelinated axons of mice. Our results reveal that maladaptive microglia activation promotes the accumulation of harmful CD8+ T cells, leading to the degeneration of myelinated axons and subsequent impairment of brain function and behavior. We characterize glial heterogeneity and aging-related changes in white matter by single-cell and spatial transcriptomics and reveal elaborate glial-immune interactions. Mechanistically, we show that the CXCL10-CXCR3 axis is crucial for the recruitment and retention of CD8+ T cells in aged white matter, where they exert pathogenic effects. Our results indicate that myelin-related microglia dysfunction promotes adaptive immune reactions in aging and identify putative targets to mitigate their detrimental impact.

Single-nucleus RNA sequencing and network pharmacology reveal the mediation of fisetin on neuroinflammation in Alzheimer's disease

BACKGROUND

Alzheimer's Disease (AD) is a neurodegenerative disorder characterized by a progressive decline in cognitive function and memory. This study explores cellular subgroups in AD using single-nucleus RNA sequencing (snRNA-seq). It integrates the pharmacological network of traditional Chinese medicine (TCM) to identify potential therapeutic targets, providing a theoretical basis for the development of clinical AD.

METHODS

We obtained data information from the Gene Expression Omnibus (GEO) for snRNA-seq analysis. Enrichment and pseudotime analysis were performed to explore the functions and differentiation pathways of cellular subgroups. Cellular communication networks were mapped to reveal subgroup interactions. Additionally, a pharmacological network for AD was constructed using the TCM pharmacology database.

RESULTS

We identified several cell subgroups associated with AD pathology, contributing to disease progression in various ways. Notably, the TNC+ CD44+ astrocyte subgroup activated the I-kappa B kinase/ NF-κB signaling pathway, leading to increased expression of inflammatory cytokines. In the pharmacological network, fisetin was identified as a promising compound with the potential to bind to the CD44 protein, mitigating the inflammatory response and preventing further neuronal damage.

CONCLUSIONS

By exploring the ecological landscape of various cellular subgroups in AD and investigating the roles and mechanisms, combined with molecular docking and pharmacological network screening, our findings provide new insights and therapeutic possibilities for AD treatment.

Glioma-neuronal circuit remodeling induces regional immunosuppression

Neuronal activity-driven mechanisms influence glioblastoma cell proliferation and invasion, while glioblastoma remodels neuronal circuits. Although a subpopulation of malignant cells enhances neuronal connectivity, their impact on the immune system remains unclear. Here, we show that glioblastoma regions with enhanced neuronal connectivity exhibit regional immunosuppression, characterized by distinct immune cell compositions and the enrichment of anti-inflammatory tumor-associated macrophages (TAMs). In preclinical models, knockout of Thrombospondin-1 (TSP1/Thbs1) in glioblastoma cells suppresses synaptogenesis and glutamatergic neuronal hyperexcitability. Furthermore, TSP1 knockout restores antigen presentation-related genes, promotes the infiltration of pro-inflammatory TAMs and CD8 + T-cells in the tumor, and alleviates TAM-mediated T-cell suppression. Pharmacological inhibition of glutamatergic signaling also shifts TAMs toward a less immunosuppressive state, prolongs survival in mice, and shows the potential to enhance the efficacy of immune cell-based therapy. These findings confirm that glioma-neuronal circuit remodeling is strongly linked with regional immunosuppression and suggest that targeting glioma-neuron-immune crosstalk could provide avenues for immunotherapy.

Restoring neuronal excitability and spatial memory through inhibiting amyloid-β-induced hyperactive NF-κB in a rat model of Alzheimer's disease

Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder associated with aberrant neuronal activity. In AD, NF-κB, a key transcription factor and inflammatory mediator, becomes hyperactive, influencing gene expression, and likely neuronal excitability. This study investigates whether inhibiting intracortical injection of amyloid-β peptides (Aβ)-induced hyperactive NF-κB can restore spatial memory impairment and abnormal neuronal activity in rats. We observed that intracortical injection of Aβ increases immunoreactivity of phosphorylated-p65 in CA1 pyramidal neurons. We demonstrated that in vivo treatment of rats with JSH-23 restores anxiety-like behaviors as well as spatial learning and memory, as assessed by elevated plus maze and Morris water maze, respectively. In addition, using patch-clamp recording we showed that the intrinsic excitability of CA1 pyramidal neurons, particularly in terms of the evoked spikes, is reduced in Aβ-injected rats along with altered resting membrane properties. Incubating acute brain slices from control rats in aCSF containing JSH-23 did not influence the neuronal activity. In contrast, this incubation restored almost all of the passive- and activity-dependent properties of CA1 pyramidal neurons in brain slices from Aβ-injected rats. Furthermore, we found that Aβ-induced enhancement of Ih currents and after-hyperpolarization amplitude (AHP) are reduced by JSH-23 incubation, possibly underlying rescuing effects of NF-κB inhibition at behavioral and cognitive level. Collectively, our results suggest that hyperactive NF-κB signaling in AD is associated with abnormal neuronal activity and deficits in cognitive functions. Moreover, pharmacologic inhibition of this signaling molecule restores neuronal excitability, as well as rescues spatial memory, likely through influencing Ih currents and AHP.

Downregulation of STAT3 transcription factor reverses synaptotoxic phenotype of reactive astrocytes associated with prion diseases

In neurodegenerative diseases, including prion diseases, astrocytes adopt reactive phenotypes that persist throughout disease progression. While astrocyte reactivity may initially serve as a protective response to prion infection, it transitions into a neurotoxic phenotype that disrupts homeostatic functions and exacerbates disease pathology. The transcription factor Stat3 has been recognized as a master regulator of astrocyte reactivity in neurodegenerative diseases, yet its role in prion disease-associated astrocyte reactive phenotypes remains unexplored. The current study addresses this gap by investigating the effects of Stat3 deletion in reactive astrocytes isolated from prion-infected mice. We demonstrate that Stat3 deletion mitigates the reactive astrocyte phenotype and alleviates their synaptotoxic effects. Stat3-dependent activation of astrocytes was reproduced by co-culturing naïve astrocytes with reactive microglia isolated from prion-infected animals or exposing them to microglia-conditioned media. A cytokine array profiling of 40 molecules revealed partially overlapping inflammatory signatures in reactive microglia and astrocytes, with IL-6 prominently upregulated in both cell types. Notably, IL-6 treatment elevated phosphorylated Stat3 levels in naïve astrocytes and triggered astrocyte reactivity. These findings indicate that the synaptotoxic phenotype of astrocytes in prion diseases can be sustained by reactive microglia and self-reinforced in a cell-autonomous manner. Our work highlights the pivotal role of Stat3 signaling in astrocyte activation and suggests that Stat3 inhibition may suppress the reactive phenotype of astrocytes associated with prion diseases.

Linking depression and neuroinflammation: Crosstalk between glial cells

The inflammatory hypothesis is one of the more widely accepted pathogenesis of depression. Glia plays an important immunomodulatory role in neuroinflammation, mediating interactions between the immune system and the central nervous system (CNS). Glial cell-driven neuroinflammation is not only an important pathological change in depression, but also a potential therapeutic target. This review discusses the association between depression and glial cell-induced neuroinflammation and elucidates the role of glial cell crosstalk in neuroinflammation. Firstly, we focus on the role of glial cells in neuroinflammation in depression and glial cell interactions; secondly, we categorize changes in different glial cells in animal models of depression and depressed patients, focusing on how glial cells mediate inflammatory responses and exacerbate depressive symptoms; Thirdly, we review how conventional and novel antidepressants affect the phenotype and function of glial cells, thereby exerting anti-inflammatory activity; finally, we discuss the role of the gut-brain axis in glial cell function and depression, and objectively analyze the problems that remain in current antidepressant therapy. This review aims to provide an objective analysis of how glial cell cross-talk may mediate neuroinflammation and thereby influence pathologic progression of depression. It is concluded that a novel therapeutic strategy may be to ameliorate glial cell-mediated inflammatory responses.

Gestational Diabetes Mellitus Rats Induce Anxiety-Depression-Like Behavior in Offspring: Association with Neuroinflammation and NF-κB Pathway

The gestational diabetes mellitus (GDM) rat model was established through a combination of high-fat diet and streptozotocin. GDM is a common disease during pregnancy with high morbidity, which is associated with a high risk of neurological changes in the offspring. Neuroinflammation plays an important role in the development of anxiety-depression-like behavior. However, the mechanisms involved are unknown. This study aimed to investigate whether GDM induces chronic neuroinflammation in the offspring, resulting in anxiety-depression-like behavior. Our study used high-fat diets and streptozotocin to establish a gestational diabetes rat model. Eight-week-old offspring were assessed for anxiety-depression-like behavior using the open field test and the modified forced swimming test. Prefrontal cortex (PFC) tissue was observed by H&E staining. The expression level of peripheral and central inflammation was monitored by ELISA. Differentially expressed genes in the PFC were detected by RNA-sequencing. The results of RNA-sequencing were verified by RT-qPCR, Western blot, and Wes™ Automatic Western Blot Quantitative Analysis. Anxiety-depression-like behavior was observed in the offspring of GDM. It indicated that PFC neurons were impaired and neuroinflammation was more serious in the GDM offspring, in which the increased concentration of CXCL10 was observed. Moreover, it revealed that the PI3K/AKT pathway was enriched by KEGG analysis. Mechanistically, GDM increased astrocyte activation and facilitated the nuclear translocation of phosphorylated-nuclear factor-κ B (p-NF-κB) in the offspring. The development of anxiety-depression-like behavior in the offspring of GDM rats was influenced by neuroinflammation in the PFC. These effects may be associated with astrocyte activation and activation of the NF-κB pathway.

Interleukin-34-dependent perivascular macrophages promote vascular function in the brain

The development of most macrophages depends on the colony-stimulating factor 1 (CSF-1) receptor, which has two ligands: CSF-1 and interleukin-34 (IL-34). While IL-34 is required for the homeostasis of microglia, the parenchymal macrophages in the central nervous system (CNS), it is unclear whether brain border-associated macrophages (BAMs) also depend on this cytokine. Here, we demonstrated that the embryonic development of murine BAMs in the choroid plexus, leptomeninges, and perivascular spaces required CSF-1, while IL-34 was critical for their maintenance in adulthood. In the brain, Il34 was expressed by mural cells and perivascular fibroblasts, and its transgenic deletion in these cells interrupted BAM maintenance. Il34 deficiency coincided with transcriptional changes in vascular cells, leading to increased flow velocity and vasomotion in pial and penetrating arterioles. Similarly, Mrc1CreCsf1rfl/fl mice lacking CD206+ perivascular BAMs exhibited increased hemodynamics in arterial networks. These findings reveal a crosstalk between vascular cells and CNS macrophages regulating cerebrovascular function.

APOE genotype determines cell-type-specific pathological landscape of Alzheimer's disease

The apolipoprotein E (APOE) gene is the strongest genetic risk modifier for Alzheimer's disease (AD), with the APOE4 allele increasing risk and APOE2 decreasing it compared with the common APOE3 allele. Using single-nucleus RNA sequencing of the temporal cortex from APOE2 carriers, APOE3 homozygotes, and APOE4 carriers, we found that AD-associated transcriptomic changes were highly APOE genotype dependent. Comparing AD with controls, APOE2 carriers showed upregulated synaptic and myelination-related pathways, preserving synapses and myelination at the protein level. Conversely, these pathways were downregulated in APOE3 homozygotes, resulting in reduced synaptic and myelination proteins. In APOE4 carriers, excitatory neurons displayed reduced synaptic pathways similar to APOE3, but oligodendrocytes showed upregulated myelination pathways like APOE2. However, their synaptic and myelination protein levels remained unchanged or increased. APOE4 carriers also showed increased pro-inflammatory signatures in microglia but reduced responses to amyloid-β pathology. These findings reveal APOE genotype-specific molecular alterations in AD across cell types.

Neuroprotective effects of the elderberry diet on the methamphetamine-induced toxicity in rats: a behavioral, electrophysiological, and histopathological study

Methamphetamine (METH) harms nerve and glial cells in both animals and humans, impacting cognitive functions and leading to research on cognitive impairments in exposed animals. Elderberry (EB) contains numerous bioactive compounds and demonstrates various health benefits, which can be valuable for maximizing its use in the food industry. In the present study, we focused on the probable protective effects of EB on the devastating impacts of METH in the hippocampus, one of the critical areas in memory and cognition. Thirty-six rats were classified into three groups, including the control, METH (10 mg/kg ip for four weeks), and METH + EB (10 mg/kg ip METH plus the EB diet for four weeks). They underwent behavioral, electrophysiological, and histological assays. The findings show an improvement in the METH-induced memory decay and anxiety-like behaviors. Further, the EB diet recovered the population spike (PS) amplitude and the field excitatory postsynaptic potential (fEPSP) slope of the evoked potentials of the LTP components in hippocampus neurocircuits. We observed a remarkable drop in the number of hippocampal astrocytes in the METH + EB group compared to the METH group. The Sholl analysis showed an increase in the soma size and total process length in hippocampal astrocytes. Moreover, the EB diet improved neuronal cell arrangement in the hippocampus of rats. Though further research is required to clarify this matter, it seems that EB can have a protective effect on the memory-related variables. However, more research is needed to clarify this.

Icaritin promotes brain functional rehabilitation in ischemic stroke rats by regulating astrocyte activation and polarization via GPER

BACKGROUND

Cerebral ischemic injury induces the polarization of astrocytes toward two different phenotypes, i.e., the proinflammatory A1 phenotype and the protective, anti-inflammatory A2 phenotype, affects the prognosis of cerebral ischemia. To explore the neuroprotective effect of phytoestrogens ICT on cerebral ischemic rehabilitation and the preliminary mechanism of regulating astrocyte polarization.

METHODS

Transient middle cerebral artery occlusion (tMCAO)/reperfusion was performed on rats and then treated with ICT (i.p.) once daily for 28 days. Intervention of GPER specific inhibitor G15 was repeated. The body weight, Garcia JH scale, right/left brain weight ratio, CatWalk gait test and Y maze test to assess overall neural function in rats. Inflammatory factors in ischemic cortical were detected by Western blotting. The number of newborn neurons was observed by BrdU staining, and the double immunofluorescence staining and Western blotting to evaluated the activation and A1 and A2 polarization of astrocytes.

RESULTS

The results showed that ICT treatment markedly perfected functional outcomes on a long-term basis after ischemic stroke, it also improved learning and memory and gait. ICT inhibited the polarization of A1 type astrocytes and promoted the polarization of A2 type astrocytes, promote neuron regeneration in hippocampus DG region. G15 removes some of the protective effects of ICT.

CONCLUSIONS

The experimental results show that ICT exerts neuroprotective effects and regulates astrocyte polarization through GPER, suggesting that it may be a potential therapeutic agent for ischemic stroke during the recovery period.

Chronic mild stress dysregulates autophagy, membrane dynamics, and lysosomal status in frontal cortex and hippocampus of rats

Inflammation has been related to major depressive disorder pathophysiology. Autophagy, a degradative pathway regulating inflammation and immunity, has emerged as a potential contributor. Among others, we characterized, in frontal cortex (FC) and hippocampus (Hp), autophagy markers (upregulations in mTOR, ATG7, and ATG 16L1, and downregulations in ULK1, BECLIN1, phospho-SQSTM1, ATG3, ATG12, and ATG 16L1), effectors of the endosomal sorting complexes required for transport (overexpression in HRS, VPS37A, CHMP6, and GALECTIN 3, and downregulations in STAM2, TSG101, VPS28, VPS37A, CHMP5, VPS4B, and GALECTIN 9), and lysosomal proteins (LAMP1, LAMP2A, MANNOSE RECEPTOR, HSC70, HSP70, CATHEPSIN D and B, and CYSTATIN C, whose variations are dependent on lysosomal nature and brain region) of male rats exposed to chronic mild stress, a model of depression, compared to control rats. Results indicate that chronic stress alters protein expression of autophagy and the endosomal sorting complexes required for transport markers in a region-specific manner, plus increases lysosomal presence, oppositely modulating lysosomal proteins in each structure. Additionally, astrocytes seemed to exert an essential role in the regulation of the autophagy adaptor SQSTM1/p62. In conclusion, stress-induced protein disruptions in these pathways highlight their differential modulation after chronic stress exposure and their potential role in maintaining brain homeostasis during the stress response, making them promising targets for new therapeutic strategies in stress-related pathologies.

The neuroimmune interface in retinal regeneration

Retinal neurodegeneration leads to irreversible blindness due to the mammalian nervous system's inability to regenerate lost neurons. Efforts to regenerate retina involve two main strategies: stimulating endogenous cells to reprogram into neurons or transplanting stem-cell derived neurons into the degenerated retina. However, both approaches must overcome a major barrier in getting new neurons to grow back down the optic nerve and connect to appropriate visual targets in environments that differ significantly from developmental conditions. While immune privilege has historically been associated with the central nervous system, an emerging literature highlights the active role of immune cells in shaping neurodegeneration and regeneration. This review explores the neuroimmune interface in retinal repair, dissecting how immune interactions influence glial reprogramming, transplantation outcomes, and axonal regeneration. By integrating insights from regenerative species with mammalian models, we highlight novel immunomodulatory strategies to optimize retinal regeneration.

Transcription Factor-Based Gene Therapy Enables Functional Repair of Rat Following Chronic Ischemic Stroke

OBJECTIVE

In vivo transcription factor (TF) -mediated gene therapy through astrocyte-to-neuron (AtN) conversion has shown therapeutic effects on rodent and non-human primate cortical ischemic injury in the subacute phase. However, in the clinic, subcortical regions including striatum as well as white matter are vulnerable regions of stroke, with millions of patients beyond subacute phase. In this study, we investigate whether TF-mediated AtN conversion therapy can be extended to treat chronic-phase ischemic stroke involving subcortical regions (e.g., striatum) and white matter, beyond cortical injuries.

METHODS

Rat middle cerebral artery occlusion (MCAO)-like models were established to induce broad ischemic injuries including cortical and striatal regions. Then multiple rounds of TF-mediated gene therapy treatments through adeno-associated virus (AAV) system to cover the large-scaled infarct areas were conducted in the chronic phase of the stroke models. Magnetic resonance imaging (MRI), [18F] FDG-PET/CT, behavioral tests, immunohistochemistry and bulk-RNA seq were applied to evaluate the AtN conversion, tissue repair and functional recovery.

RESULTS

Our results revealed that administrated in the chronic phase of ischemic stroke, TF-mediated gene therapy can efficiently regenerate new neurons in both cortical and striatal regions, and promote tissue repair in both grey and white matter. Compared with single round of AAV administration, multiple rounds of treatment regenerated more neurons and led to a significant functional recovery.

CONCLUSIONS

Our study demonstrates that TF-mediated gene therapy has a broad therapeutic time window and can be applied multiple rounds to treat severe ischemic stroke, making it an attractive therapeutic intervention in the chronic phase after stroke, when current approaches are largely ineffective.

Disentangling the Switching Behavior in Functional Connectivity Dynamics in Autism Spectrum Disorder: Insights from Developmental Cohort Analysis and Molecular-Cellular Associations

Characterizing the transition or switching behavior between multistable brain states in functional connectivity dynamics (FCD) holds promise for uncovering the underlying neuropathology of Autism Spectrum Disorder (ASD). However, whether and how switching behaviors in FCD change in patients with developmental ASD, as well as their cellular and molecular basis, remains unexplored. This study develops a region-wise FCD switching index (RFSI) to investigate the drivers of FCD. This work finds that brain regions within the salience, default mode, and frontoparietal networks serve as abnormal drivers of FCD in ASD across different developmental stages. Additionally, changes in RFSI at different developmental stages of ASD correlated with transcriptomic profiles and neurotransmitter density maps. Importantly, the abnormal RFSI identifies in humans has also been observed in genetically edited ASD monkeys. Finally, single-nucleus RNA sequencing data from patients with developmental ASD are analyzed and aberrant switching behaviors in FCD may be mediated by somatostatin-expressing interneurons and altered differentiation patterns in astrocyte State2. In conclusion, this study provides the first evidence of abnormal drivers of FCD across different stages of ASD and their associated cellular and molecular mechanisms. These findings deepen the understanding of ASD neuropathology and offer valuable insights into treatment strategies.

ASTROCYTES AND ALCOHOL THROUGHOUT THE LIFESPAN

Evidence for involvement of astrocytes in several neurodegenerative disorders and in drug addiction has been emerging over the last two decades, but only in recent years have astrocytes been investigated for their roles in alcohol use disorder (AUD). As a result, there is a need to evaluate existing preclinical literature supporting involvement of astrocytes in the effects of alcohol exposure. Here we review emerging evidence about responses of astrocytes to alcohol, and the contributions of astrocytes to the development of AUD. We review studies of single-cell RNA sequencing with a focus on alcohol and astrocyte heterogeneity, astrocyte reactivity, and the role of astrocytes in remodeling the extracellular matrix. Effects of alcohol on astrocyte-modulated synaptic transmission are also discussed emphasizing studies never reviewed before. Since astrocytes play essential roles in brain development, we review recent research on the role of astrocytes in fetal alcohol spectrum disorders (FASD) which may also shed light on fetal development of psychiatric disorders that have a high prevalence in individuals affected by FASD. Finally, this review highlights gaps in knowledge about astrocyte biology and alcohol that need further research. Particularly, the dire need to identify astrocyte subpopulations and molecules that are susceptible to alcohol exposure and may be targets for therapeutic intervention.

Papain Affects the Percentage and Morphology of Microglia in Hippocampal Neuron-Glial Cultures

Background. Microglia, accounting for 5-15% of total brain cells, represent an essential population of glial cells in the cultures used for modeling neuroinflammation in vitro. However, microglia proliferation is poor in neuron-glial cultures. Here, we studied the population composition of rat hippocampal neuron-glial cell cultures prepared utilizing papain (PAP cultures) and trypsin (TRY cultures) as proteolytic enzymes for cell isolation. Methods. To evaluate the percentage and morphology of microglia in TRY and PAP cultures and cultures incubated in the presence of TGFβ+MCSF+cholesterol, which should enhance microglia proliferation, we used an immunostaining and calcium imaging approach in combination with staining using the recently developed vital microglia fluorescent probe CDr20. Results. We have shown that the microglia percentage in PAP cultures was higher than in TRY cultures. Microglia in PAP cultures are predominantly polarized, while bushy morphology was more characteristic of TRY cultures. We have also demonstrated that the TGFβ+MCSF+cholesterol combination increases the microglia number both in PAP and TRY cultures (up to 25-30%) and promotes the appearance of ameboid microglia characterized by high mobility. However, the significant appearance of ameboid microglia was observed already at the early stages of cultivation (2 DIV) in TRY cultures, while in PAP cultures, the described transformation was observed at 7 DIV. Based on the absence of the ATP-induced Ca2+ response, round shape, significant proliferation, and high mobility, we have suggested that ameboid microglia are reactive. Conclusions. Thus, our results demonstrate that papain is a more suitable proteolytic enzyme for preparing mixed hippocampal neuron-glial cultures with a higher percentage of heterogeneous microglia and functional neurons and astrocytes (tricultures).

Neuroinflammation and stress-induced pathophysiology in major depressive disorder: mechanisms and therapeutic implications

Major depressive disorder (MDD) is one of the most common mental health conditions, characterized by pervasive and persistent low mood, low self-esteem, and a loss of interest or pleasure in activities that are typically enjoyable. Despite decades of research into the etiology and pathophysiological mechanisms of depression, the therapeutic outcomes for many individuals remain less than expected. A promising new area of research focuses on stress-induced neuroinflammatory processes, such as the excessive activation and crosstalk of microglia and astrocytes in the central nervous system under stress, as well as elevated levels of pro-inflammatory cytokines, which are closely linked to the onset and progression of depression. This review summarizes the mechanisms through which neuroinflammation induces or promotes the development of depression, and also highlights the effective roles of small molecules with anti-inflammatory activity in the treatment of MDD. Understanding the specific mechanisms through which stress-induced neuroinflammation further impacts depression, and using technologies such as single-cell RNA sequencing to elucidate the specific subtypes and interactions of microglia and astrocytes in depression, is of great importance for developing more effective therapeutic strategies for MDD.

The Role of Astrocytes in the Molecular Pathophysiology of Schizophrenia: Between Neurodevelopment and Neurodegeneration

Schizophrenia is a chronic and severe psychiatric disorder affecting approximately 1% of the global population, characterized by disrupted synaptic plasticity and brain connectivity. While substantial evidence supports its classification as a neurodevelopmental disorder, non-canonical neurodegenerative features have also been reported, with increasing attention given to astrocytic dysfunction. Overall, in this study, we explore the role of astrocytes as a structural and functional link between neurodevelopment and neurodegeneration in schizophrenia. Specifically, we examine how astrocytes contribute to forming an aberrant substrate during early neurodevelopment, potentially predisposing individuals to later neurodegeneration. Astrocytes regulate neurotransmitter homeostasis and synaptic plasticity, influencing early vulnerability and disease progression through their involvement in Ca2⁺ signaling and dopamine-glutamate interaction-key pathways implicated in schizophrenia pathophysiology. Astrocytes differentiate via nuclear factor I-A, Sox9, and Notch pathways, occurring within a neuronal environment that may already be compromised in the early stages due to the genetic factors associated with the 'two-hits' model of schizophrenia. As a result, astrocytes may contribute to the development of an altered neural matrix, disrupting neuronal signaling, exacerbating the dopamine-glutamate imbalance, and causing excessive synaptic pruning and demyelination. These processes may underlie both the core symptoms of schizophrenia and the increased susceptibility to cognitive decline-clinically resembling neurodegeneration but driven by a distinct, poorly understood molecular substrate. Finally, astrocytes are emerging as potential pharmacological targets for antipsychotics such as clozapine, which may modulate their function by regulating glutamate clearance, redox balance, and synaptic remodeling.

Drp1 mitochondrial fission in astrocyte modulates behavior and neuroinflammation during morphine addiction

BACKGROUND

Mitochondrial dynamics in neurons accompanied by neuroinflammation has been proved as pivotal events during repeated morphine exposure, however, the relationship between mitochondrial dynamics and neuroinflammation still remains unknown.

METHODS

This study was designed to investigate the potential role of astrocyte Drp1 in neuroinflammation during morphine addiction. Nucleus accumbens (NAc) tissues were collected for immunofluorescence, transmission electron microscopy (TEM) and quantitative real-time polymerase chain reaction (qRT-PCR) to detect the expression of pro-inflammatory cytokines and mitochondrial fission proteins. Morphine-induced conditioned place preference (CPP) and open field test (OFT) were used to determine the effects of Mdivi-1, a selective inhibitor of mitochondrial fission protein Drp1 in the rewarding properties of morphine. Astrocyte-specific knockdown experiments by an adeno-associated virus (AAV) vector containing shRNADrp1-EGFP infusion were performed to determine the effects of astrocyte Drp1 in NAc of mice with morphine treatment.

RESULTS

In this study, we found that repeated morphine exposure induced mitochondrial fragmentation in neurons, astrocytes, and microglia in NAc, correlating with increased inflammatory markers and addictive behaviors. The application of Mdivi-1 effectively mitigated mitochondrial fragmentation and astrocyte-mediated neuroinflammation within the NAc, thereby alleviating morphine-induced addictive behaviors. Crucially, the astrocyte-specific knockdown of Drp1 in NAc significantly curtailed drug-seeking behavior and substantially reduced neuroinflammation.

CONCLUSIONS

Collectively, our findings suggest that alterations in mitochondrial dynamics, particularly within astrocytes, play an important role in regulating neuroinflammation associated with morphine addiction. This research offers novel insights into potential therapeutic strategies for addressing substance use disorder (SUD) by regulating mitochondrial dynamics within astrocyte.

Upregulating mTOR/S6 K Pathway by CASTOR1 Promotes Astrocyte Proliferation and Myelination in Gpam-/--induced mouse model of cerebral palsy

GPAM, a key enzyme for lipid synthesis, is predominantly expressed in astrocytes (ASTs), where it facilitates lipid supply for myelin formation. Our previous studies identified GPAM as a novel causative gene for cerebral palsy (CP) and led to the development of a CP mouse model with GPAM deficiency (Gpam-/-). The model closely recapitulated the clinical phenotype of children with CP, due to the restricted proliferation of ASTs in the brain, reduced the amount of lipid, thinner brain white matter, and myelin dysplasia. The mammalian target of rapamycin (mTOR) pathway plays an important role in cell proliferation and lipid synthesis. Cytosolic arginine sensor (CASTOR1) interacts with GATOR2 to regulate mTOR complex 1 (mTORC1). Targeted degradation of CASTOR1 can activate the mTOR pathway. However, it remains unclear the involvement of mTOR pathway in neurological diseases such as CP. In this study, we demonstrated that the mTOR pathway was inhibited in Gpam-/- mice. Notably, CASTOR1 could regulate the activity of mTOR/S6K pathway, functioning as a negative upstream regulator. Furthermore, inhibition of CASTOR1 upregulated mTOR/S6K signaling, promoting astrocyte proliferation and myelination, which in turn enhanced motor function in the Gpam-/--induced CP mouse model. Collectively, these findings reveal the role of astrocytic mTOR in the pathogenesis of CP mice, broaden the therapeutic strategies, and provide a promising candidate target for CP treatment.

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.

The roles of immune factors in neurodevelopment

The development of the nervous system is a highly complex process orchestrated by a multitude of factors, including various immune elements. These immune components play a dual role, not only regulating the immune response but also actively influencing brain development under both physiological and pathological conditions. The brain's immune barrier includes microglia in the brain parenchyma, which act as resident macrophages, astrocytes that support neuronal function and contribute to the inflammatory response, as well as circulating immune cells that reside at the brain's borders, including the choroid plexus, meninges, and perivascular spaces. Cytokines-soluble signaling molecules released by immune cells-play a crucial role in mediating communication between immune cells and the developing nervous system. Cytokines regulate processes such as neurogenesis, synaptic pruning, and inflammation, helping to shape the neural environment. Dysregulation of these immune cells, astrocytes, or cytokine signaling can lead to alterations in neurodevelopment, potentially contributing to neurodevelopmental abnormalities. This article reviews the central role of microglia, astrocytes, cytokines, and other immune factors in neurodevelopment, and explores how neuroinflammation can lead to the onset of neurodevelopmental disorders, shedding new light on their pathogenesis.

Engineered endoplasmic reticulum-targeting nanodrugs with Piezo1 inhibition and promotion of cell uptake for subarachnoid hemorrhage inflammation repair

Subarachnoid hemorrhage (SAH) is a life-threatening acute hemorrhagic cerebrovascular condition, often presenting with severe headaches caused by intracranial hypertension, which in severe cases can lead to brain herniation. Piezo1 is a mechanosensitive ion channel protein whose mechanical properties are closely linked to central nervous system diseases. In this study, we developed an engineered endoplasmic reticulum membrane-based nanomedicine (CAQKERM@GsMTx4) using HEK293T cells, aimed at targeted delivery to acute hemorrhagic regions, rapid absorption, and precise inhibition of Piezo1 therapy. To ensure optimal targeting and therapeutic efficacy, we fused the CAQK peptide gene to the N-terminus of TRP-PK1, presenting the CAQK peptide on the endoplasmic reticulum membrane, and loaded GsMTx4 into engineered vesicles (EVs) derived from this engineered membrane. Through in vivo and in vitro experiments and multi-omics analysis, we have demonstrated the marked advantages of endoplasmic reticulum membrane vesicles over cell membrane-based vesicles. CAQKERM@GsMTx4 successfully inhibits Piezo1 in SAH, helps microglia change from the M1 phenotype to the M2 phenotype, and inhibits inflammatory responses and neuronal damage. Overall, this novel engineered endoplasmic reticulum membrane nanomedicine provides a potential effective strategy for the clinical treatment of subarachnoid hemorrhage.

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.

Microglial Depletion, a New Tool in Neuroinflammatory Disorders: Comparison of Pharmacological Inhibitors of the CSF-1R

A growing body of evidence highlights the importance of microglia, the resident immune cells of the CNS, and their pro-inflammatory activation in the onset of many neurological diseases. Microglial proliferation, differentiation, and survival are highly dependent on the CSF-1 signaling pathway, which can be pharmacologically modulated by inhibiting its receptor, CSF-1R. Pharmacological inhibition of CSF-1R leads to an almost complete microglial depletion whereas treatment arrest allows for subsequent repopulation. Microglial depletion has shown promising results in many animal models of neurodegenerative diseases (Alzheimer's disease (AD), Parkinson's disease, or multiple sclerosis) where transitory microglial depletion reduced neuroinflammation and improved behavioral test results. In this review, we will focus on the comparison of three different pharmacological CSF-1R inhibitors (PLX3397, PLX5622, and GW2580) regarding microglial depletion. We will also highlight the promising results obtained by microglial depletion strategies in adult models of neurological disorders and argue they could also prove promising in neurodevelopmental diseases associated with microglial activation and neuroinflammation. Finally, we will discuss the lack of knowledge about the effects of these strategies on neurons, astrocytes, and oligodendrocytes in adults and during neurodevelopment.

Targeting chaperone-mediated autophagy in neurodegenerative diseases: mechanisms and therapeutic potential

The pathological hallmarks of various neurodegenerative diseases including Parkinson's disease and Alzheimer's disease prominently feature the accumulation of misfolded proteins and neuroinflammation. Chaperone-mediated autophagy (CMA) has emerged as a distinct autophagic process that coordinates the lysosomal degradation of specific proteins bearing the pentapeptide motif Lys-Phe-Glu-Arg-Gln (KFERQ), a recognition target for the cytosolic chaperone HSC70. Beyond its role in protein quality control, recent research underscores the intimate interplay between CMA and immune regulation in neurodegeneration. In this review, we illuminate the molecular mechanisms and regulatory pathways governing CMA. We further discuss the potential roles of CMA in maintaining neuronal proteostasis and modulating neuroinflammation mediated by glial cells. Finally, we summarize the recent advancements in CMA modulators, emphasizing the significance of activating CMA for the therapeutic intervention in neurodegenerative diseases.

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.

Immunotherapy and the Tumor Microenvironment in Brain Metastases from Non-Small Cell Lung Cancer: Challenges and Future Directions

Brain metastases (BMs) are a relatively common and severe complication in advanced non-small cell lung cancer (NSCLC), significantly affecting patient prognosis. Metastatic tumor cells can alter the brain tumor microenvironment (TME) to promote an immunosuppressive state, characterized by reduced infiltration of tumor-infiltrating lymphocytes (TILs), diminished expression of programmed death-ligand 1 (PD-L1), and changes in other proinflammatory factors and immune cell populations. Microglia, the resident macrophages of the brain, play a pivotal role in modulating the central nervous system (CNS) microenvironment through interactions with metastatic cancer cells, astrocytes, and infiltrating T cells. The M2 phenotype of microglia contributes to immunosuppression in BM via the activation of signaling pathways such as STAT3 and PI3K-AKT-mTOR. Recent advances have enhanced our understanding of the immune landscape of BMs in NSCLC, particularly regarding immune evasion within the CNS. Current immunotherapeutic strategies, including immune checkpoint inhibitors, have shown promise for NSCLC patients with BM, demonstrating intracranial activity and manageable safety profiles. Future research is warranted to further explore the molecular and immune mechanisms underlying BM, aiming to develop more effective treatments.

A New Human SCARB2 Knock-In Mouse Model for Studying Coxsackievirus A16 and Its Neurotoxicity

Hand, Foot, and Mouth Disease (HFMD) is a viral illness caused by enterovirus infections. While the introduction of the enterovirus 71 (EV71) vaccine has significantly reduced the number of EV71-related cases, the continued spread of Coxsackievirus A16 (CVA16) remains a major public health threat. Previous studies have shown that human SCARB2 (hSCARB2) knock-in (KI) mice, generated using embryonic stem cell (ESC) technology, are susceptible to CVA16. However, these models have failed to reproduce the clinical pathology and neurotoxicity after CVA16 infection. Therefore, there is an urgent need for a more reliable and effective animal model to study CVA16. In this study, we successfully created a hSCARB2 KI mouse model targeting the ROSA26 locus using CRISPR/Cas9 gene editing technology. The application of CRISPR/Cas9 enabled stable and widespread expression of hSCARB2 in the model. After infection, the KI mice exhibited a clinical pathology that closely mimics human infection, with prominent limb weakness and paralysis. The virus was detectable in multiple major organs of the mice, with peak viral load observed on day 7 post-infection, gradually clearing thereafter. Further analysis revealed widespread neuronal necrosis and infiltration of inflammatory cells in the brain and spinal cord of the KI mice. Additionally, significant activation of astrocytes (GFAP-positive) and microglia (IBA1-positive) was observed in the brain, suggesting that CVA16 infection may induce limb paralysis by attacking neuronal cells. Overall, this model effectively replicates the neuropathological changes induced by CVA16 infection and provides a potential experimental platform for studying CVA16-associated pathogenesis and neurotoxicity.

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.

H3K18 lactylation-mediated nucleotide-binding oligomerization domain-2 (NOD2) expression promotes bilirubin-induced pyroptosis of astrocytes

Histone lactylation, a newly glycosis-related histone modification, plays a crucial role in the regulation of gene expression in various immune cells. However, the role of histone lactylation in astrocytes remains unclear. Here, this study showed that the H3K18 lactylation (H3K18la) levels were upregulated in primary astrocytes under unconjugated bilirubin (UCB) stimulation and hippocampus of bilirubin encephalopathy (BE) rats. Inhibition of glycolysis decreased H3K18la and attenuated pyroptosis both in vitro and in vivo. CUT& Tag and RNA-seq results revealed that H3K18la was enriched at the promoter of nucleotide-binding oligomerization domain 2 (NOD2) and promoted its transcription. Moreover, NOD2 boosted the activation of downstream mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) signaling pathways, which exacerbated the neuroinflammation of BE. Collectively, this study provides a novel understanding of epigenetic regulation in astrocytes, and interruption of the H3K18la/NOD2 axis may represent a novel therapeutic strategy for treating bilirubin encephalopathy.

Short-term lipopolysaccharide treatment leads to astrocyte activation in LRRK2 G2019S knock-in mice without loss of dopaminergic neurons

BACKGROUND

The G2019S mutation of LRRK2, which enhances kinase activity of the protein, confers a substantial risk of developing Parkinson's disease (PD). However, the mutation demonstrates incomplete penetrance, suggesting the involvement of other genetic or environmental modulating factors. Here, we investigated whether LRRK2 G2019S knock-in (KI) mice treated with the inflammogen lipopolysaccharide (LPS) could model LRRK2 PD.

RESULTS

We found that short-term (2 weeks) treatment with LPS did not result in the loss of dopaminergic neurons in either LRRK2 G2019S KI or wild-type (WT) mice. Compared with WT mice, LRRK2 G2019S-KI mice showed incomplete recovery from LPS-induced weight loss. In LRRK2 G2019S KI mice, LPS treatment led to upregulated phosphorylation of LRRK2 at the autophosphorylation site Serine 1292, which is known as a direct readout of LRRK2 kinase activity. LPS treatment caused a greater increase in the activated astrocyte marker glial fibrillary acidic protein (GFAP) in the striatum and substantia nigra of LRRK2 G2019S mice than in those of WT mice. The administration of caffeine, which was recently identified as a biomarker of resistance to developing PD in individuals with LRRK2 mutations, attenuated LPS-induced astrocyte activation specifically in LRRK2 G2019S KI mice.

CONCLUSIONS

Our findings suggest that 2 weeks of exposure to LPS is not sufficient to cause dopaminergic neuronal loss in LRRK2 G2019S KI mice but rather results in increased astrocyte activation, which can be ameliorated by caffeine.

The role of senescence-related genes in major depressive disorder: insights from machine learning and single cell analysis

BACKGROUND

Evidence indicates that patients with Major Depressive Disorder (MDD) exhibit a senescence phenotype or an increased susceptibility to premature senescence. However, the relationship between senescence-related genes (SRGs) and MDD remains underexplored.

METHODS

We analyzed 144 MDD samples and 72 healthy controls from the GEO database to compare SRGs expression. Using Random Forest (RF) and Support Vector Machine-Recursive Feature Elimination (SVM-RFE), we identified five hub SRGs to construct a logistic regression model. Consensus cluster analysis, based on SRGs expression patterns, identified subclusters of MDD patients. Weighted Gene Co-expression Network Analysis (WGCNA) identified gene modules strongly linked to each cluster. Single-cell RNA sequencing was used to analyze MDD SRGs functions.

RESULTS

The five hub SRGs: ALOX15B, TNFSF13, MARCH 15, UBTD1, and MAPK14 showed differential expression between MDD patients and controls. Diagnostics models based on these hub genes demonstrated high accuracy. The hub SRGs correlated positively with neutrophils and negatively with T lymphocytes. SRGs expression pattern revealed two distinct MDD subclusters. WGCNA identified significant gene modules within these subclusters. Additionally, individual endothelial cells with high senescence scores were found to interact with astrocytes via the Notch signaling pathway, suggesting a specific role in MDD pathogenesis.

CONCLUSION

This comprehensive study elucidates the significant role of SRGs in MDD, highlighting the importance of the Notch signaling pathway in mediating senescence effects.

Multiple Sclerosis and Other Acquired Demyelinating Diseases of the Central Nervous System

Acquired demyelinating diseases of the central nervous system (CNS) comprise inflammatory conditions, including multiple sclerosis (MS) and related diseases, as well as noninflammatory conditions caused by toxic, metabolic, infectious, traumatic, and neurodegenerative insults. Here, we review the spectrum of diseases producing acquired CNS demyelination before focusing on the prototypical example of MS, exploring the pathologic mechanisms leading to myelin injury in relapsing and progressive MS and summarizing the mechanisms and modulators of remyelination. We highlight the complex interplay between the immune system, oligodendrocytes and oligodendrocyte progenitor cells (OPCs), and other CNS glia cells such as microglia and astrocytes in the pathogenesis and clinical course of MS. Finally, we review emerging therapeutic strategies that exploit our growing understanding of disease mechanisms to limit progression and promote remyelination.

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

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

Decreased water exchange rate across the blood-brain barrier throughout the Alzheimer's disease continuum: Evidence from Chinese data

INTRODUCTION

Water exchange rate (Kw) across the blood-brain barrier (BBB) is used in magnetic resonance imaging (MRI) techniques to evaluate BBB functionality. Variations in BBB Kw across the Alzheimer's disease (AD) continuum remain uncertain.

METHODS

The study encompassed 38 cognitively normal individuals without AD biomarkers (CN_A-), 30 cognitively normal (CN_A+), and 31 cognitively impaired individuals (CI_A+) with positive AD biomarkers. Participants underwent clinical assessments, MRI/positron emission tomography scans, and assays of plasma biomarkers.

RESULTS

Significantly lower Kw was observed in multiple brain regions throughout the AD continuum. This alteration in Kw correlated with plasma biomarkers and neuropsychological performance. Elevated levels of phosphorylated tau 217 intensified the inverse relationship between Kw and neuropsychological performance. The integration of Kw, brain volume, and plasma biomarkers demonstrated potential in distinguishing stages within the AD continuum.

DISCUSSION

Consistently lower Kw was evident across the AD continuum and may act as a diagnostic tool for early AD screening.

HIGHLIGHTS

Observations revealed a decline in water exchange rate (Kw) across multiple brain regions within the Alzheimer's disease (AD) continuum, notably in the hippocampus, parahippocampal gyrus, and deep brain nuclei during the preclinical stage of AD. Strong correlations were established between Kw levels in various brain regions and plasma biomarkers, as well as neuropsychological performance in the AD continuum. Interaction between plasma phosphorylated tau (p-tau)217 and Kw in the hippocampus was linked to executive function, indicating a combined detrimental impact on cognitive abilities stemming from both blood-brain barrier Kw and p-tau 217. The combined use of Kw, brain volume, and plasma biomarkers-neurofilament light chain and glial fibrillary acidic protein-demonstrated potential for distinguishing individuals within the AD continuum.

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

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

Meningeal lymphatic vessel crosstalk with central nervous system immune cells in aging and neurodegenerative diseases

Meningeal lymphatic vessels form a relationship between the nervous system and periphery, which is relevant in both health and disease. Meningeal lymphatic vessels not only play a key role in the drainage of brain metabolites but also contribute to antigen delivery and immune cell activation. The advent of novel genomic technologies has enabled rapid progress in the characterization of myeloid and lymphoid cells and their interactions with meningeal lymphatic vessels within the central nervous system. In this review, we provide an overview of the multifaceted roles of meningeal lymphatic vessels within the context of the central nervous system immune network, highlighting recent discoveries on the immunological niche provided by meningeal lymphatic vessels. Furthermore, we delve into the mechanisms of crosstalk between meningeal lymphatic vessels and immune cells in the central nervous system under both homeostatic conditions and neurodegenerative diseases, discussing how these interactions shape the pathological outcomes. Regulation of meningeal lymphatic vessel function and structure can influence lymphatic drainage, cerebrospinal fluid-borne immune modulators, and immune cell populations in aging and neurodegenerative disorders, thereby playing a key role in shaping meningeal and brain parenchyma immunity.

Decoding TGR5: A comprehensive review of its impact on cerebral diseases

Currently, unraveling the enigmatic realm of drug targets for cerebral disorders poses a formidable challenge. Takeda G protein-coupled receptor 5 (TGR5), also known as G protein-coupled bile acid receptor 1, is a specific bile acid receptor. Widely distributed across various tissues, TGR5 orchestrates a myriad of biological functions encompassing inflammation, energy metabolism, fatty acid metabolism, immune responses, cellular proliferation, apoptosis, and beyond. Alongside its well-documented implications in liver diseases, obesity, type 2 diabetes, tumors, and cardiovascular diseases, a growing body of evidence accentuates the pivotal role of TGR5 in cerebral diseases. Thus, this comprehensive review aimed to scrutinize the current insights into the pathological mechanisms involving TGR5 in cerebral diseases, while contemplating its potential as a promising therapeutic target for cerebral diseases.

3-HKA Promotes Vascular Remodeling After Stroke by Modulating the Activation of A1/A2 Reactive Astrocytes

Ischemic stroke is the most common cerebrovascular disease and the leading cause of permanent disability worldwide. Recent studies have shown that stroke development and prognosis are closely related to abnormal tryptophan metabolism. Here, significant downregulation of 3-hydroxy-kynurenamine (3-HKA) in stroke patients and animal models is identified. Supplementation with 3-HKA improved long-term neurological recovery, reduced infarct volume, and increased ipsilateral cerebral blood flow after distal middle cerebral artery occlusion (MCAO). 3-HKA promoted angiogenesis, functional blood vessel formation, and blood-brain barrier (BBB) repair. Moreover, 3-HKA inhibited A1-like (neurotoxic) astrocyte activation but promoted A2-like (neuroprotective) astrocyte polarization. Proteomic analysis revealed that 3-HKA inhibited AIM2 inflammasome activation after stroke, and co-labeling studies indicated that AIM2 expression typically increased in astrocytes at 7 and 14 days after stroke. Consistently, in co-cultures of primary mouse brain microvascular endothelial cells and astrocytes, 3-HKA promoted angiogenesis after oxygen-glucose deprivation (OGD). AIM2 overexpression in astrocytes abrogated 3-HKA-driven vascular remodeling in vitro and in vivo, suggesting that 3-HKA may regulate astrocyte-mediated vascular remodeling by impeding AIM2 inflammasome activation. In conclusion, 3-HKA may promote post-stroke vascular remodeling by regulating A1/A2 astrocyte activation, thereby improving long-term neurological recovery, suggesting that supplementation with 3-HKA may be an efficient therapy for stroke.

Mitochondrial fatty acid oxidase CPT1A ameliorates postoperative cognitive dysfunction by regulating astrocyte ferroptosis

BACKGROUND

Postoperative cognitive dysfunction (POCD) is a significant surgery-related complication marked by cognitive decline. Studies indicated that neuroinflammation, ferroptosis, and mitochondrial fatty acid metabolism might play parts in POCD, and might be mediated by Carnitine palmitoyl transferase 1a (CPT1A), but requires further investigations. Therefore, this study aims to investigate the mechanism of mitochondrial fatty acid oxidase CPT1A on mitochondrial function, ferroptosis, and inflammation in POCD pathogenesis.

METHODS

SVG P12 astrocytes were used to investigate CPT1A's control over mitochondrial function, ferroptosis, and inflammation affecting neurons. CPT1A was overexpressed using shRNA, with or without oligomycin to modulate mitochondrial function. Co-culture of these astrocytes with neurons, under similar conditions, assessed CPT1A's impact on neuron damage via ferroptosis and inflammation. Gene and protein expressions of CPT1A, SYN, PSD95 were measured via RT-PCR and WB. Detection of JC-1, mitochondrial oxygen consumption rate (OCR), ROS, Fe2+ concentration, MOD, SOD and GSH/GSSG using kits was conducted to explore mitochondrial function and ferroptosis. Inflammation was quantified by ELISA for IL-6, IL-1β, and TGF-β.

RESULTS

We successfully established CPT1A overexpression and knockdown models in astrocytes, confirming CPT1A's ability to enhance mitochondrial membrane potential. Elevated CPT1A levels led to improved mitochondrial function, synaptic integrity, reduced oxidative stress, maintained iron homeostasis, and attenuated neuroinflammation, as reflected by increased SYN, PSD95, OCR, GSH and SOD, decreased ROS,GSSG, MDA, iron levels, and lowered inflammatory factors expression. Treatment with oligomycin reversed these protective effects, demonstrating the dependency of CPT1A's benefits on intact mitochondrial respiration. In co-culture experiments with hippocampal neurons, astrocytes with manipulated CPT1A levels, particularly those co-treated with oligomycin, exacerbated neuronal mitochondrial dysfunction, oxidative stress, iron accumulation, and inflammation.

CONCLUSION

Overexpression of mitochondrial fatty acid oxidase CPT1A might improve synaptic integrity and rescue POCD by ameliorating astrocyte ferroptosis and neuroinflammation.

Nuclear receptor 4A1 facilitates complete Freund's adjuvant-induced inflammatory pain in rats by promoting ferroptosis in spinal glial cells

Glial cell-induced neuroinflammation in the spinal cord is the critical pathology underlying complete Freund's adjuvant (CFA)-induced inflammatory pain. Previously, we showed that spinal glial cells undergo ferroptosis after CFA injection, which may contribute to the development of neuroinflammation and inflammatory pain. However, the mechanism underlying the occurrence of ferroptosis during inflammatory pain remains unclear. The aim of this study was to investigate the molecular factors involved in the occurrence of ferroptosis during the development of inflammatory pain. Bulk and single-cell RNA sequencing were performed to identify the key genes involved in the ferroptosis of spinal astrocytes, microglia, and oligodendrocytes in rats. We identified nuclear receptor 4A1 (NR4A1) as a common ferroptosis-related gene present in all three types of glial cells. Western blotting and immunostaining revealed increased NR4A1 levels in the spinal glial cells of the CFA-treated rats. Moreover, intrathecal injection of DIM-C-pPhOH (an NR4A1 inhibitor) effectively alleviated mechanical and thermal hypersensitivity in the CFA-treated rats by attenuating ferroptosis and neuroinflammation in spinal glial cells. Proteomic analysis revealed that mitogen-activated protein kinase 3 (MAPK3) may be the target protein of NR4A1. In addition, the combined results of chromatin immunoprecipitation and dual-luciferase assays indicated that NR4A1 can bind to the promoter region and promote transcription of MAPK3, ultimately leading to lipid peroxidation. In conclusion, this study demonstrated that increased expression of NR4A1 promotes the progression of CFA-induced inflammatory pain by enhancing ferroptosis through the transcriptional activation of MAPK3 and subsequent lipid peroxidation. Furthermore, inhibition of NR4A1 was found to suppress ferroptosis and reduce the release of pro-inflammatory cytokines in the spinal cord of rats with inflammatory pain. Collectively, these findings outline a novel pathological mechanism and identify potential therapeutic targets for the treatment of inflammatory pain.

CLEC16A in astrocytes promotes mitophagy and limits pathology in a multiple sclerosis mouse model

Astrocytes promote neuroinflammation and neurodegeneration in multiple sclerosis (MS) through cell-intrinsic activities and their ability to recruit and activate other cell types. In a genome-wide CRISPR-based forward genetic screen investigating regulators of astrocyte proinflammatory responses, we identified the C-type lectin domain-containing 16A gene (CLEC16A), linked to MS susceptibility, as a suppressor of nuclear factor-κB (NF-κB) signaling. Gene and small-molecule perturbation studies in mouse primary and human embryonic stem cell-derived astrocytes in combination with multiomic analyses established that CLEC16A promotes mitophagy, limiting mitochondrial dysfunction and the accumulation of mitochondrial products that activate NF-κB, the NLRP3 inflammasome and gasdermin D. Astrocyte-specific Clec16a inactivation increased NF-κB, NLRP3 and gasdermin D activation in vivo, worsening experimental autoimmune encephalomyelitis, a mouse model of MS. Moreover, we detected disrupted mitophagic capacity and gasdermin D activation in astrocytes in samples from individuals with MS. These findings identify CLEC16A as a suppressor of astrocyte pathological responses and a candidate therapeutic target in MS.