Acute ischemia induces spatially and transcriptionally distinct microglial subclusters

Inhibition of the cGAS-STING pathway: contributing to the treatment of cerebral ischemia-reperfusion injury

The cGAS-STING pathway plays an important role in ischemia-reperfusion injury in the heart, liver, brain, and kidney, but its role and mechanisms in cerebral ischemia-reperfusion injury have not been systematically reviewed. Here, we outline the components of the cGAS-STING pathway and then analyze its role in autophagy, ferroptosis, cellular pyroptosis, disequilibrium of calcium homeostasis, inflammatory responses, disruption of the blood-brain barrier, microglia transformation, and complement system activation following cerebral ischemia-reperfusion injury. We further analyze the value of cGAS-STING pathway inhibitors in the treatment of cerebral ischemia-reperfusion injury and conclude that the pathway can regulate cerebral ischemia-reperfusion injury through multiple mechanisms. Inhibition of the cGAS-STING pathway may be helpful in the treatment of cerebral ischemia-reperfusion injury.

Evobrutinib mitigates neuroinflammation after ischemic stroke by targeting M1 microglial polarization via the TLR4/Myd88/NF-κB pathway

BACKGROUND

Evobrutinib, a third-generation Bruton's tyrosine kinase (BTK) inhibitor, shows great promise for treating neuroinflammatory diseases due to its small molecular size, ease of absorption, and ability to cross the blood-brain barrier. Although previous studies have confirmed significant BTK expression in microglia, the potential of Evobrutinib to treat ischemic stroke by modulating microglial function and its underlying mechanisms remain to be elucidated.

METHODS

Male C57BL/6 mice with cerebral ischemia was established to evaluate the effects of oral Evobrutinib treatment. Assessments included TTC staining, behavioral experiments, and pathological examinations were used to evaluate cerebral ischemic injury. Western Blot, flow cytometry, and qPCR were employed to monitor changes in BTK and pBTK expression in microglia and the impact of Evobrutinib on neuroinflammation following the stroke. In vitro, primary microglia were generated to determine the effects of Evobrutinib on the TLR4/ Myd88/NF-κB pathway and on the polarization of microglial subtypes.

RESULTS

The expression of BTK and pBTK is upregulated in microglia under conditions of cerebral ischemia and oxygen-glucose deprivation (OGD). Evobrutinib treatment not only reduced infarct volume in mice but also ameliorated pathological damage and facilitated neurological function recovery. Flow cytometry revealed that Evobrutinib decreased inflammatory cell infiltration and promoted M2 microglia polarization post-stroke. In vitro studies demonstrated that Evobrutinib downregulated the proportion of pro-inflammatory microglia and curtailed the secretion of inflammatory factors under OGD conditions. Mechanistically, Evobrutinib attenuated the OGD-induced upregulation of TLR4/Myd88/NF-κB expression, an effect that was further enhanced by the addition of the TLR4 pathway inhibitor TAK242.

CONCLUSIONS

Evobrutinib inhibits the expression and activation of BTK in microglia, reducing M1 microglia-mediated neuroinflammation and alleviating ischemic injury following stroke. This effect is mechanistically linked to the inhibition of TLR4/Myd88/NF-κB-mediated M1 polarization of microglia.

Post-cerebral ischemia energy crisis: the role of glucose metabolism in the energetic crisis

BACKGROUND

Cells universally employ an efficiency-driven metabolic switch mechanism during nutritional changes, growth, and differentiation, transitioning from oxidative phosphorylation (OXPHOS) to glycolysis to ensure survival under hypoxic conditions or high energy demands. In cerebral ischemia, inadequate blood supply causes oxygen and energy deprivation, prompting brain cells to initiate glycolytic reprogramming to meet urgent energy needs. While this adaptation is a temporary solution, it may lead to lactic acidosis, aggravated inflammation, and increased free radical production. Prolonged reperfusion with sustained glycolysis can exacerbate brain cell damage, potentially causing irreversible harm.

OBJECTIVES

This review systematically examines the dynamic changes in glucose metabolic transport mechanisms and the roles of immediate, early, intermediate, and late responder cells, along with their regulatory factors, in glycolytic reprogramming.

METHODS

Using a temporal analysis framework based on the body's natural response sequence to pathological events, we elucidate how cells at different stages collaborate to address glucose metabolism reprogramming under pathological conditions.

CONCLUSIONS

Reversing glucose metabolism reprogramming and inhibiting glycolysis may improve the pathological processes of ischemic stroke, offering potential therapeutic benefits.

Advances in brain ischemia mechanisms and treatment approaches: Recent insights and inflammation-driven risks

The application of existing radical treatments for stroke is limited to a small number of cases, with current practices predominantly focusing on conservative therapy. This review examines the pathophysiology of excitotoxicity, oxidative stress, and inflammation during brain ischemia caused by stroke, highlighting insights into each pathology and reporting the latest therapeutic developments that are expected to serve as new treatment options. Finally, we outline the recent attention given to the relationship between periodontal disease and stroke. We propose addressing the limitations of existing treatments for stroke and suggest novel therapeutic approaches while also presenting the potential contribution of periodontal disease treatment to the prevention of stroke.

Single-cell RNA sequencing reveals ECM remodeling-tumor stiffness-FAK as a key driver of vestibular schwannoma progression

Vestibular schwannoma (VS), characterized by the absence of merlin expression, is the most prevalent benign tumor located at the cerebellopontine angle, lacking approved pharmaceutical interventions except for off-label utilization of bevacizumab. The role of Tumor stiffness-Focal adhesion kinase (FAK) activation in fueling tumor progression is well-established, with merlin deficiency serving as a biomarker for tumor sensitivity to FAK inhibitors. In this context, we investigated whether Tumor stiffness-FAK contributes to VS progression. Single-cell RNA sequencing revealed associations between VS progression and gene sets related to "Response to mechanical stimulus" and "Neurotrophin signaling pathway". Histological studies indicated a potential involvement of neurotrophins in early stages of VS tumorigenesis, while enhanced Extracellular matrix (ECM) remodeling-Tumor stiffness-FAK signaling accompanies later stages of VS progression. In vitro experiments demonstrated that elevated matrix stiffness induces cytoskeletal remodeling, cell proliferation, and metalloproteinase expression in VS cells by activating FAK. Conversely, FAK inhibition diminishes these effects. Collectively, this study suggests that ECM remodeling-Tumor stiffness contributes to VS progression via FAK activation, positioning FAK as a promising therapeutic target in treating VS.

Integrated bioinformatics analysis and biological experiments to identify key immune genes in vascular dementia

Objectives

This study aimed to identify key immune genes to provide new perspectives on the mechanisms and diagnosis of vascular dementia (VaD) based on bioinformatic methods combined with biological experiments in mice.

Methods

We obtained gene expression profiles from a Gene Expression Omnibus database (GSE186798). The gene expression data were analysed using integrated bioinformatics and machine learning techniques to pinpoint potential key immune-related genes for diagnosing VaD. Moreover, the diagnostic accuracy was evaluated through receiver operating characteristic curve analysis. The microRNA, transcription factor (TF), and drug-regulating hub genes were predicted using the database. Immune cell infiltration has been studied to investigate the dysregulation of immune cells in patients with VaD. To evaluate cognitive impairment, mice with bilateral common carotid artery stenosis (BCAS) were subjected to behavioural tests 30 d after chronic cerebral hypoperfusion. The expression of hub genes in the BCAS mice was determined using a quantitative polymerase chain reaction(qPCR).

Results

The results of gene set enrichment and gene set variation analyses indicated that immune-related pathways were upregulated in patients with VaD. A total of 1620 immune genes were included in the combined immune dataset, and 323 differentially expressed genes were examined using the GSE186798 dataset. Thirteen potential genes were identified using differential gene analysis. Protein-protein interaction network design and functional enrichment analysis were performed using the immune system as the main subject. To evaluate the diagnostic value, two potential core genes were selected using machine learning. Two putative hub genes, Rac family small GTPase 1(RAC1) and CKLF-like MARVEL transmembrane domain containing 5 (CMTM5) exhibit good diagnostic value. Their high confidence levels were confirmed by validating each biomarker using a different dataset. According to GeneMANIA, VaD pathophysiology is strongly associated with immune and inflammatory responses. The data were used to construct miRNA hub gene, TFs-hub gene, and drug-hub gene networks. Varying levels of immune cell dysregulation were also observed. In the animal experiments, a BCAS mouse model was employed to mimic VaD in humans, further confirmed using the Morris water maze test. The mRNA expression of RAC1 and CMTM5 was significantly reduced in the BCAS group, which was consistent with the results of the integrated bioinformatics analysis.

Conclusions

RAC1 and CMTM5 are differentially expressed in the frontal lobes of BCAS mice, suggesting their potential as biomarkers for diagnosing and prognosis of VaD. These findings pave the way for exploring novel molecular mechanisms aimed at preventing or treating VaD.

Identification of NETs-related genes as diagnostic biomarkers in ischemic stroke using RNA sequencing and single-cell analysis

Neutrophil extracellular traps (NETs) are increasingly recognized for their involvement in ischemic stroke (IS), yet their precise contribution to IS outcomes is not fully understood. This study aims to elucidate the role of NETs in IS progression and identify potential biomarkers and therapeutic targets. In this study, mice were subjected to middle cerebral artery occlusion (MCAO). RNA sequencing was conducted on brain tissue samples to identify differentially expressed genes (DEGs) using the "limma" package. The diagnostic potential of these biomarkers was assessed using receiver operating characteristic (ROC) curve analysis. Additionally, single-cell RNA sequencing data were analyzed with the Seurat package to further investigate the cellular dynamics. We identified DEGs, and NETs-related genes associated with IS progression. Specifically, Ceacam3, Tnf, Selp, and Fcgr4 were found to be upregulated in MCAO samples, exhibiting diagnostic value as biomarkers for IS. Immune infiltration analysis indicated associations between these genes and various immune cell types. Gene Set Enrichment Analysis (GSEA) revealed their involvement in IS-related pathways, including ferroptosis, IL-17 signaling, leukocyte transendothelial migration, necroptosis, and NETs formation. Single-cell data confirmed the expression of Tnf, Selp, and Fcgr4 in neutrophils. CellChat analysis uncovered key cell-cell interactions in IS, emphasizing the role of neutrophils in communicating with microglia and T cells via the JAM pathway, with Thbs1 and Cd47 as key mediators. The findings provide insights into the cellular and molecular mechanisms underlying IS and may pave the way for novel therapeutic strategies targeting NETs in IS patients.

Association of TAB2 gene polymorphism with endometrial cancer susceptibility and clinical analysis

Objective

Transforming growth factor-β-activated kinase 1 binding protein 2 (TAB2) plays a vital role in inflammatory pathways. It has also been considered a potential target for the enhancement of the the antiestrogen effects. Previous evidence has indicated that TAB2 gene variants are associated with several diseases, whereas their potential correlation with endometrial cancer (EC) is unclear. This study aims to initially explore the association between TAB2 gene polymorphisms (rs237028 /AG, rs521845 T/G, and rs652921 T/C) and EC.

Materials and Methods

Polymerase chain reaction-restriction fragment length polymorphism was applied to determine the genotype composition and the allele frequencies of TAB2 gene variant polymorphisms in 270 EC patients and 294 healthy controls.

Results

The G allele of rs521845 was related to the increase of EC risk [p=0.08, odds ratio (OR): 0.72, 95% confidence interval (CI): 0.56-0.91]. Moreover, EC risk was associated with rs521845 in different genetic models (p=0.017, OR: 0.63, 95% CI: 0.44-0.91 in the codominant model; p=0.0051, OR: 0.61, 95% CI: 0.43-0.87 in the dominant model). For rs237028, the percentage of AG genotype in patients with highly differentiated tumours (G1) was significantly higher than that in moderately, poorly differentiated patients (G2/G3) (p=0.031, OR: 0.77, 95% CI: 0.45-1.30).

Conclusion

Our results showed that the rs521845 polymorphism of TAB2, was associated with EC risk, suggesting that TAB2 may play a crucial role in EC prognosis.

Long-Term Minocycline Treatment Exhibits Enhanced Therapeutic Effects on Ischemic Stroke by Suppressing Inflammatory Phenotype of Microglia Through the EMB/MCT4/STING Pathway

BACKGROUND

Neuroinflammation caused by excessive activation of microglia is a significant cause of poor prognosis in ischemic stroke patients. Minocycline, a microglial cell inhibitor, has neuroprotective effects in stroke, but its optimal treatment duration and specific mechanisms of action remain unclear. This study aimed to compare the efficacy of different minocycline treatment durations on stroke and explore their mechanisms of action.

METHODS

We investigated the effects of various durations of minocycline treatment on microglial polarization using cellular and animal models. The mechanisms of long-term minocycline therapy for neuroprotective effects were explored through in vitro and in vivo experiments.

RESULTS

In stroke models, long-term minocycline treatment showed a stronger inhibitory effect on neuroinflammation and improved neuron viability compared with short-term treatment. Further in vitro and in vivo results indicated that long-term minocycline treatment downregulated microglial glycolysis levels through the EMB/MCT4 axis, promoting the transformation of microglia to an anti-inflammatory phenotype by inhibiting the activation of the STING pathway, thereby improving post-stroke neuroinflammation.

CONCLUSION

Long-term minocycline therapy exerts neuroprotective effects in ischemic stroke by regulating the EMB/MCT4/STING axis and inhibiting the inflammatory phenotype of microglia through downregulating cellular glycolysis levels. Extending the treatment duration of minocycline appropriately may further improve ischemic stroke outcomes.

The Multifaceted Roles of BACH1 in Disease: Implications for Biological Functions and Therapeutic Applications

BTB domain and CNC homolog 1 (BACH1) belongs to the family of basic leucine zipper proteins and is expressed in most mammalian tissues. It can regulate its own expression and play a role in transcriptionally activating or inhibiting downstream target genes. It has a crucial role in various biological processes, such as oxidative stress, cell cycle, heme homeostasis, and immune regulation. Recent research highlights BACH1's significant regulatory roles in a series of conditions, including stem cell pluripotency maintenance and differentiation, growth, senescence, and apoptosis. BACH1 is closely associated with cardiovascular diseases and contributes to angiogenesis, atherosclerosis, restenosis, pathological cardiac hypertrophy, myocardial infarction, and ischemia/reperfusion (I/R) injury. BACH1 promotes tumor cell proliferation and metastasis by altering tumor metabolism and the epithelial-mesenchymal transition phenotype. Moreover, BACH1 appears to show an adverse role in diseases such as neurodegenerative diseases, gastrointestinal disorders, leukemia, pulmonary fibrosis, and skin diseases. Inhibiting BACH1 may be beneficial for treating these diseases. This review summarizes the role of BACH1 and its regulatory mechanism in different cell types and diseases, proposing that precise targeted intervention of BACH1 may provide new strategies for human disease prevention and treatment.

Glial 'omics in ischemia: Acute stroke and chronic cerebral small vessel disease

Vascular injury and pathologies underlie common diseases including ischemic stroke and cerebral small vessel disease (CSVD). Prior work has identified a key role for glial cells, including microglia, in the multifaceted and temporally evolving neuroimmune response to both stroke and CSVD. Transcriptional profiling has led to important advances including identification of distinct gene expression signatures in ischemia-exposed, flow cytometrically sorted microglia and more recently single cell RNA sequencing-identified microglial subpopulations or clusters. There is a reassuring degree of overlap in the results from these two distinct methodologies with both identifying a proliferative and a separate type I interferon responsive microglial element. Similar patterns were later seen using multimodal and spatial transcriptomal profiling in ischemia-exposed microglia and astrocytes. Methodological advances including enrichment of specific neuroanatomic/functional regions (such as the neurovascular unit) prior to single cell RNA sequencing has led to identification of novel cellular subtypes and generation of new credible hypotheses as to cellular function based on the enhanced cell sub-type specific gene expression patterns. A ribosomal tagging strategy focusing on the cellular translatome analyses carried out in the acute phases post stroke has revealed distinct inflammation-regulating roles for microglia and astrocytes in this setting. Early spatial transcriptomics experiments using cerebral ischemia models have identified regionally distinct microglial cell clusters in ischemic core versus penumbra. There is great potential for combination of these methods for multi-omics approaches to further elucidate glial responses in the context of both acute ischemic stroke and chronic CSVD.

In Vivo Time-Resolved Single-Cell RNA-Seq Reveals Chemotherapy-Induced Transcriptional Dynamics in Tumor Infiltrating Lymphocytes

Single-cell RNA sequencing (scRNA-seq) using metabolic RNA labeling enables detailed analysis of dynamic gene expression within single cells. However, most studies are limited to in vitro settings, restricting the exploration of in vivo transcriptomic dynamics. To address this, we developed scDyna-seq, a time-resolved scRNA-seq method for in vivo applications using 4-thiouridine (4sU) labeling. scDyna-seq efficiently captures nascent RNA, allowing for precise tracking of gene expression in both in vitro and in vivo contexts, including crossing the blood-brain and blood-fetal barriers. It is also compatible with other single-cell multiomics approaches. In a mouse bladder cancer model, scDyna-seq revealed that cisplatin (cis-diaminodichloroplatinum, CDDP) induced significant dynamic changes in tumor-infiltrating lymphocytes, particularly in genes related to costimulation, effector functions, and exhaustion, which were not detected by conventional methods. When coupled with scTCR-seq, scDyna-seq showed increased TCR clonal expansion linked to CDDP-induced immunogenic death and neoantigen production. In conclusion, scDyna-seq offers safe, precise in vivo RNA labeling as well as single-cell analysis, expanding our understanding of cellular dynamics and facilitating research in health and disease.

Microglial Regulation of Neural Networks in Neuropsychiatric Disorders

Microglia serve as vital innate immune cells in the central nervous system, playing crucial roles in the generation and development of brain neurons, as well as mediating a series of immune and inflammatory responses. The morphologic transitions of microglia are closely linked to their function. With the advent of single-cell sequencing technology, the diversity of microglial subtypes is increasingly recognized. The intricate interactions between microglia and neuronal networks have significant implications for psychiatric disorders and neurodegenerative diseases. A deeper investigation of microglia in neurologic diseases such as Alzheimer disease, depression, and epilepsy can provide valuable insights in understanding the pathogenesis of diseases and exploring novel therapeutic strategies, thereby addressing issues related to central nervous system disorders.

β2 integrin regulates neutrophil trans endothelial migration following traumatic brain injury

Neutrophils are the first responders among peripheral immune cells to infiltrate the central nervous system following a traumatic brain injury (TBI), triggering neuroinflammation that can exacerbate secondary tissue damage. The precise molecular controls that dictate the inflammatory behavior of neutrophils post-TBI, however, remain largely elusive. Our comprehensive analysis of the molecular landscape surrounding the trauma in TBI mice has revealed a significant alteration in the abundance of β2 integrin (ITGB2), predominantly expressed by neutrophils and closely associated with immune responses. Using the fluid percussion injury (FPI) mouse model, we investigated the therapeutic efficacy of Rovelizumab, an agent that blocks ITGB2. The treatment has demonstrated significant improvements in neurologic function in TBI mice, attenuating blood-brain barrier permeability, mitigating oxidative stress and inflammatory mediator release, and enhancing cerebral perfusion. Moreover, ITGB2 blockade has effectively limited the adherence, migration, and infiltration of neutrophils, and has impeded the formation of neutrophil extracellular traps (NETs) upon their activation. Finally, it was demonstrated that ITGB2 mediates these effects mainly through its interaction with intercellular adhesion molecule-1 (ICAM 1) of endotheliocyte. These findings collectively illuminate ITGB2 as a crucial molecular switch that governs the adverse effects of neutrophils post-TBI and could be targeted to improve clinical outcome in patients.

The immunology of stroke and dementia

Ischemic stroke and vascular cognitive impairment, caused by a sudden arterial occlusion or more subtle but protracted vascular insufficiency, respectively, are leading causes of morbidity and mortality worldwide with limited therapeutic options. Innate and adaptive immunity have long been implicated in neurovascular injury, but recent advances in methodology and new experimental approaches have shed new light on their contributions. A previously unappreciated dynamic interplay of brain-resident, meningeal, and systemic immune cells with the ischemic brain and its vasculature has emerged, and new insights into the frequent overlap between vascular and Alzheimer pathology have been provided. Here, we critically review these recent findings, place them in the context of current concepts on neurovascular pathologies and Alzheimer's disease, and highlight their impact on recent stroke and Alzheimer therapies.

Monitoring of single-nucleus chromatin landscape of ischemic stroke in mouse cerebral cortex across time

Ischemic stroke constitutes a multifaceted neurological affliction that spans various cellular types. Lack of dynamic chromatin accessibility data after stroke is one of the obstacles to understanding this process. To gain insights into the variations in transcriptional regulation among various cell types subsequent to a stroke, we employed single-nucleus ATAC-seq to curate a chromatin accessibility compendium from the cerebral cortex of mice subjected to middle cerebral artery occlusion/reperfusion (MCAO/R). Tissue samples were collected at various time points including 0, 6, 12, 24 hours, and 7, 14 days post-reperfusion, in addition to Sham control group. We obtained 99,271 high-quality nuclei across nine cell types, thereby establishing the single-nucleus chromatin accessibility atlas. This atlas provides data for interpreting the regulatory mechanisms that pervade the continuum of ischemic stroke. The data presented herein constitutes a valuable resource for the comprehension of regulatory interplays within the pathology-afflicted cerebrum.

High spatial resolution gene expression profiling and characterization of neuroblasts migrating in the peri-injured cortex using photo-isolation chemistry

In the ventricular-subventricular-zone (V-SVZ) of the postnatal mammalian brain, immature neurons (neuroblasts) are generated from neural stem cells throughout their lifetime. These V-SVZ-derived neuroblasts normally migrate to the olfactory bulb through the rostral migratory stream, differentiate into interneurons, and are integrated into the preexisting olfactory circuit. When the brain is injured, some neuroblasts initiate migration toward the lesion and attempt to repair the damaged neuronal circuitry, but their low regeneration efficiency prevents functional recovery. Elucidation of the molecular basis of neuroblast migration toward lesions is expected to lead to the development of new therapeutic strategies for brain regenerative medicine. Here, we show gene expression profiles of neuroblasts migrating in the peri-injured cortex compared with those migrating in the V-SVZ using photo-isolation chemistry, a method for spatial transcriptome analysis. Differentially expressed gene analysis showed that the expression levels of 215 genes (97 upregulated and 118 downregulated genes) were significantly different in neuroblasts migrating in the peri-injured cortex from those migrating in the V-SVZ. Gene Ontology analysis revealed that in neuroblasts migrating in the peri-injured cortex, expression of genes involved in regulating migration direction and preventing cell death was upregulated, while the expression of genes involved in cell proliferation and maintenance of the immature state was downregulated. Indeed, neuroblasts migrating in the peri-injured cortex had significantly lower Cyclin D2 mRNA and Ki67 protein expression levels than those in the V-SVZ. In the injured brain, amoeboid microglia/macrophages expressed transforming growth factor-β (TGF-β), and neuroblasts migrating in the peri-injured cortex expressed TGF-β receptors. Experiments using primary cultured neuroblasts showed that application of TGF-β significantly decreased proliferating cells labeled with BrdU. These data suggest that the proliferative activity of neuroblasts migrating toward lesions is suppressed by TGF-β secreted from cells surrounding the lesion. This is the first comprehensive study characterizing the gene expression profiles of neuroblasts migrating in the peri-injured cortex.

Neuroprotective Effects of Eugenol Acetate Against Ischemic Stroke

Objective

To explore the neuroprotective effect of Eugenol Acetate (EA) on post-stroke neuroinflammation and investigate the underlying mechanisms.

Methods

For in vitro experiments, primary microglia were pre-incubated with EA for 2 hours, followed by lipopolysaccharide (LPS) stimulation for 24 hours or Oxygen-Glucose Deprivation (OGD) treatment for 4 hours. Real-time quantitative PCR, enzyme-linked immunosorbent assay (ELISA) and Western blot were performed to examine the expression levels of inflammatory cytokines in primary microglia. The activation of NF-κB signaling pathway was evaluated by immunofluorescence staining and Western blot. For in vivo experiments, middle cerebral artery occlusion (MCAO) was constructed to mimic ischemic brain injury on 8-week-old male C57BL/6J mice. The mice were continuously injected intraperitoneally with EA or vehicle after MCAO. Neurobehavioral tests and TTC staining were conducted to estimate the neurological deficits and infarct area. Moreover, the white matter integrity after MCAO was observed via immunofluorescence staining.

Results

EA significantly reduced the expression of pro-inflammatory cytokines in LPS or OGD treated primary microglia, and inhibited LPS-induced activation of the NF-κB signaling pathway. In addition, EA alleviated ischemic brain injury and improved neuromotor function of MCAO mice. Furthermore, long-term neurological deficits and white matter integrity were improved by EA treatment after MCAO.

Conclusion

EA alleviated ischemic injury and restored white matter integrity in MCAO mice, which might be associated with the inhibition of NF-κB signaling pathway in microglia. Therefore, EA might be a promising candidate for the treatment of ischemic stroke.

Single-cell RNA sequencing in stroke and traumatic brain injury: Current achievements, challenges, and future perspectives on transcriptomic profiling

Single-cell RNA sequencing (scRNA-seq) is a high-throughput transcriptomic approach with the power to identify rare cells, discover new cellular subclusters, and describe novel genes. scRNA-seq can simultaneously reveal dynamic shifts in cellular phenotypes and heterogeneities in cellular subtypes. Since the publication of the first protocol on scRNA-seq in 2009, this evolving technology has continued to improve, through the use of cell-specific barcodes, adoption of droplet-based systems, and development of advanced computational methods. Despite induction of the cellular stress response during the tissue dissociation process, scRNA-seq remains a popular technology, and commercially available scRNA-seq methods have been applied to the brain. Recent advances in spatial transcriptomics now allow the researcher to capture the positional context of transcriptional activity, strengthening our knowledge of cellular organization and cell-cell interactions in spatially intact tissues. A combination of spatial transcriptomic data with proteomic, metabolomic, or chromatin accessibility data is a promising direction for future research. Herein, we provide an overview of the workflow, data analyses methods, and pros and cons of scRNA-seq technology. We also summarize the latest achievements of scRNA-seq in stroke and acute traumatic brain injury, and describe future applications of scRNA-seq and spatial transcriptomics.

Glycolytic reprogramming in microglia: A potential therapeutic target for ischemic stroke

Ischemic stroke is currently the second leading cause of mortality worldwide, with limited treatment options available. As resident immune cells, microglia promptly respond to cerebral ischemic injury, influencing neuroinflammatory damage and neurorepair. Studies suggest that microglia undergo metabolic reprogramming from mitochondrial oxidative phosphorylation to glycolysis in response to ischemia, significantly impacting their function during ischemic stroke. Therefore, this study aims to investigate the roles and regulatory mechanisms involved in this process, aiming to identify a new therapeutic target or potential drug candidate.

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.

The interplay between ferroptosis and inflammation: therapeutic implications for cerebral ischemia-reperfusion

Stroke ranks as the second most significant contributor to mortality worldwide and is a major factor in disability. Ischemic strokes account for 71% of all stroke incidences globally. The foremost approach to treating ischemic stroke prioritizes quick reperfusion, involving methods such as intravenous thrombolysis and endovascular thrombectomy. These techniques can reduce disability but necessitate immediate intervention. After cerebral ischemia, inflammation rapidly arises in the vascular system, producing pro-inflammatory signals that activate immune cells, which in turn worsen neuronal injury. Following reperfusion, an overload of intracellular iron triggers the Fenton reaction, resulting in an excess of free radicals that cause lipid peroxidation and damage to cellular membranes, ultimately leading to ferroptosis. The relationship between inflammation and ferroptosis is increasingly recognized as vital in the process of cerebral ischemia-reperfusion (I/R). Inflammatory processes disturb iron balance and encourage lipid peroxidation (LPO) through neuroglial cells, while also reducing the activity of antioxidant systems, contributing to ferroptosis. Furthermore, the lipid peroxidation products generated during ferroptosis, along with damage-associated molecular patterns (DAMPs) released from ruptured cell membranes, can incite inflammation. Given the complex relationship between ferroptosis and inflammation, investigating their interaction in brain I/R is crucial for understanding disease development and creating innovative therapeutic options. Consequently, this article will provide a comprehensive introduction of the mechanisms linking ferroptosis and neuroinflammation, as well as evaluate potential treatment modalities, with the goal of presenting various insights for alleviating brain I/R injury and exploring new therapeutic avenues.

Single-cell sequencing to multi-omics: technologies and applications

Cells, as the fundamental units of life, contain multidimensional spatiotemporal information. Single-cell RNA sequencing (scRNA-seq) is revolutionizing biomedical science by analyzing cellular state and intercellular heterogeneity. Undoubtedly, single-cell transcriptomics has emerged as one of the most vibrant research fields today. With the optimization and innovation of single-cell sequencing technologies, the intricate multidimensional details concealed within cells are gradually unveiled. The combination of scRNA-seq and other multi-omics is at the forefront of the single-cell field. This involves simultaneously measuring various omics data within individual cells, expanding our understanding across a broader spectrum of dimensions. Single-cell multi-omics precisely captures the multidimensional aspects of single-cell transcriptomes, immune repertoire, spatial information, temporal information, epitopes, and other omics in diverse spatiotemporal contexts. In addition to depicting the cell atlas of normal or diseased tissues, it also provides a cornerstone for studying cell differentiation and development patterns, disease heterogeneity, drug resistance mechanisms, and treatment strategies. Herein, we review traditional single-cell sequencing technologies and outline the latest advancements in single-cell multi-omics. We summarize the current status and challenges of applying single-cell multi-omics technologies to biological research and clinical applications. Finally, we discuss the limitations and challenges of single-cell multi-omics and potential strategies to address them.

Natural products: A potential immunomodulators against inflammatory-related diseases

The incidence and prevalence of inflammatory-related diseases (IRDs) are increasing worldwide. Current approved treatments for IRDs in the clinic are combat against inhibiting the pro-inflammatory cytokines. Though significant development in the treatment in the IRDs has been achieved, the severe side effects and inefficiency of currently practicing treatments are endless challenge. Drug discovery from natural sources is efficacious over a resurgence and also natural products are leading than the synthetic molecules in both clinical trials and market. The use of natural products against IRDs is a conventional therapeutic approach since it is a reservoir of unique structural chemistry, accessibility and bioactivities with reduced side effects and low toxicity. In this review, we discuss the cause of IRDs, treatment of options for IRDs and the impact and adverse effects of currently practicing clinical drugs. As well, the significant role of natural products against various IRDs, the limitations in the clinical development of natural products and thus pave the way for development of natural products as immunomodulators against IRDs are also discussed.

AZD1390, an ataxia telangiectasia mutated inhibitor, attenuates microglia-mediated neuroinflammation and ischemic brain injury

AIMS

Excessive neuroinflammation mediated mainly by microglia plays a crucial role in ischemic stroke. AZD1390, an ataxia telangiectasia mutated (ATM) specific inhibitor, has been shown to promote radio-sensitization and survival in central nervous system malignancies, while the role of AZD1390 in ischemic stroke remains unknown.

METHODS

Real-time PCR, western blot, immunofluorescence staining, flow cytometry and enzyme-linked immunosorbent assays were used to assess the activation of microglia and the release of inflammatory cytokines. Behavioral tests were performed to measure neurological deficits. 2,3,5-Triphenyltetrazolium chloride staining was conducted to assess the infarct volume. The activation of NF-κB signaling pathway was explored through immunofluorescence staining, western blot, co-immunoprecipitation and proximity ligation assay.

RESULTS

The level of pro-inflammation cytokines and activation of NF-κB signaling pathway was suppressed by AZD1390 in vitro and in vivo. The behavior deficits and infarct size were partially restored with AZD1390 treatment in experimental stroke. AZD1390 restrict ubiquitylation and sumoylation of the essential regulatory subunit of NF-κB (NEMO) in an ATM-dependent and ATM-independent way respectively, which reduced the activation of the NF-κB pathway.

CONCLUSION

AZD1390 suppressed NF-κB signaling pathway to alleviate ischemic brain injury in experimental stroke, and attenuated microglia activation and neuroinflammation, which indicated that AZD1390 might be an attractive agent for the treatment of ischemic stroke.

Neuroprotective effects of Aucubin against cerebral ischemia-reperfusion injury

AIMS

To study the role of Aucubin (AU) in cerebral ischemia-reperfusion injury and investigate the potential mechanisms.

METHODS

For the in vitro experiment, primary microglia were cultured and stimulated by Lipopolysaccharides (LPS) and treated with AU. Male C57/BL6J mice were used and middle cerebral artery occlusion (MCAO) model was performed to induce cerebral ischemia-reperfusion injury. For the short-term effects, mice administrated with AU (40 mg/kg) for 3 days after MCAO were evaluated for the infarct volume and neurological deficits. The neuroinflammatory factors and microglia activation were determined by Real-time PCR, western blot and immunofluorescence staining. For the long-term effects, MCAO mice were injected daily with AU (5 mg/kg or 10 mg/kg) for 28 days. Behavior tests were used to assess the neurological deficits of MCAO mice, and white matter integrity was determined by myelin basic protein (MBP) staining and black-gold staining.

RESULTS

AU suppressed LPS-induced activation of microglia and pro-inflammatory cytokines release, and downregulated the NF-κB and MAPK pathways in primary microglia. In addition, AU attenuated ischemic injury and inhibited the neuro-inflammatory response in MCAO mice. Moreover, AU induced prolonged improvements in sensorimotor function and memory function following MCAO, and preserved white matter integrity in the long-term experiments.

CONCLUSIONS

AU protected against ischemic injury, which might be correlated with the downregulation of NF-κB and MAPK signaling pathways. Furthermore, AU alleviated cognitive impairment after stroke and restored white matter integrity. Our data indicated that AU might be a potential compound for the treatment of stroke and post-stroke cognitive impairment.

SRGN amplifies microglia-mediated neuroinflammation and exacerbates ischemic brain injury

BACKGROUND

Microglia is the major contributor of post-stroke neuroinflammation cascade and the crucial cellular target for the treatment of ischemic stroke. Currently, the endogenous mechanism underlying microglial activation following ischemic stroke remains elusive. Serglycin (SRGN) is a proteoglycan expressed in immune cells. Up to now, the role of SRGN on microglial activation and ischemic stroke is largely unexplored.

METHODS

Srgn knockout (KO), Cd44-KO and wild-type (WT) mice were subjected to middle cerebral artery occlusion (MCAO) to mimic ischemic stroke. Exogenous SRGN supplementation was achieved by stereotactic injection of recombinant mouse SRGN (rSRGN). Cerebral infarction was measured by 2,3,5-triphenyltetrazolium chloride (TTC) staining. Neurological functions were evaluated by the modified neurological severity score (mNSS) and grip strength. Microglial activation was detected by Iba1 immunostaining, morphological analysis and cytokines' production. Neuronal death was examined by MAP2 immunostaining and FJB staining.

RESULTS

The expression of SRGN and its receptor CD44 was significantly elevated in the ischemic mouse brains, especially in microglia. In addition, lipopolysaccharide (LPS) induced SRGN upregulation in microglia in vitro. rSRGN worsened ischemic brain injury in mice and amplified post-stroke neuroinflammation, while gene knockout of Srgn exerted reverse impacts. rSRGN promoted microglial proinflammatory activation both in vivo and in vitro, whereas Srgn-deficiency alleviated microglia-mediated inflammatory response. Moreover, the genetic deletion of Cd44 partially rescued rSRGN-induced excessed neuroinflammation and ischemic brain injury in mice. Mechanistically, SRGN boosted the activation of NF-κB signal, and increased glycolysis in microglia.

CONCLUSION

SRGN acts as a novel therapeutic target in microglia-boosted proinflammatory response following ischemic stroke.

Acute ischemia induces spatially and transcriptionally distinct microglial subclusters

BACKGROUND

Damage in the ischemic core and penumbra after stroke affects patient prognosis. Microglia immediately respond to ischemic insult and initiate immune inflammation, playing an important role in the cellular injury after stroke. However, the microglial heterogeneity and the mechanisms involved remain unclear.

METHODS

We first performed single-cell RNA-sequencing (scRNA-seq) and spatial transcriptomics (ST) on middle cerebral artery occlusion (MCAO) mice from three time points to determine stroke-associated microglial subclusters and their spatial distributions. Furthermore, the expression of microglial subcluster-specific marker genes and the localization of different microglial subclusters were verified on MCAO mice through RNAscope and immunofluorescence. Gene set variation analysis (GSVA) was performed to reveal functional characteristics of microglia sub-clusters. Additionally, ingenuity pathway analysis (IPA) was used to explore upstream regulators of microglial subclusters, which was confirmed by immunofluorescence, RT-qPCR, shRNA-mediated knockdown, and targeted metabolomics. Finally, the infarct size, neurological deficits, and neuronal apoptosis were evaluated in MCAO mice after manipulation of specific microglial subcluster.

RESULTS

We discovered stroke-associated microglial subclusters in the brains of MCAO mice. We also identified novel marker genes of these microglial subclusters and defined these cells as ischemic core-associated (ICAM) and ischemic penumbra-associated (IPAM) microglia, according to their spatial distribution. ICAM, induced by damage-associated molecular patterns, are probably fueled by glycolysis, and exhibit increased pro-inflammatory cytokines and chemokines production. BACH1 is a key transcription factor driving ICAM generation. In contrast, glucocorticoids, which are enriched in the penumbra, likely trigger IPAM formation, which are presumably powered by the citrate cycle and oxidative phosphorylation and are characterized by moderate pro-inflammatory responses, inflammation-alleviating metabolic features, and myelinotrophic properties.

CONCLUSIONS

ICAM could induce excessive neuroinflammation, aggravating brain injury, whereas IPAM probably exhibit neuroprotective features, which could be essential for the homeostasis and survival of cells in the penumbra. Our findings provide a biological basis for targeting specific microglial subclusters as a potential therapeutic strategy for ischemic stroke.