Modulators of microglia activation and polarization in ischemic stroke (Review)

Pterostilbene improves neurological dysfunction and neuroinflammation after ischaemic stroke via HDAC3/Nrf1-mediated microglial activation

BACKGROUND

Stroke is a type of acute brain damage that can lead to a series of serious public health challenges. Demonstrating the molecular mechanism of stroke-related neural cell degeneration could help identify a more efficient treatment for stroke patients. Further elucidation of factors that regulate microglia and nuclear factor (erythroid-derived 2)-like 1 (Nrf1) may lead to a promising strategy for treating neuroinflammation after ischaemic stroke. In this study, we investigated the possible role of pterostilbene (PTS) in Nrf1 regulation in cell and animal models of ischaemia stroke.

METHODS

We administered PTS, ITSA1 (an HDAC activator) and RGFP966 (a selective HDAC3 inhibitor) in a mouse model of middle cerebral artery occlusion-reperfusion (MCAO/R) and a model of microglial oxygen‒glucose deprivation/reperfusion (OGD/R). The brain infarct size, neuroinflammation and microglial availability were also determined. Dual-luciferase reporter, Nrf1 protein stability and co-immunoprecipitation assays were conducted to analyse histone deacetylase 3 (HDAC3)/Nrf1-regulated Nrf1 in an OGD/R-induced microglial injury model.

RESULTS

We found that PTS decreased HDAC3 expression and activity, increased Nrf1 acetylation in the cell nucleus and inhibited the interaction of Nrf1 with p65 and p65 accumulation, which reduced infarct volume and neuroinflammation (iNOS/Arg1, TNF-α and IL-1β levels) after ischaemic stroke. Furthermore, the CSF1R inhibitor PLX5622 induced elimination of microglia and attenuated the therapeutic effect of PTS following MCAO/R. In the OGD/R model, PTS relieved OGD/R-induced microglial injury and TNF-α and IL-1β release, which were dependent on Nrf1 acetylation through the upregulation of HDAC3/Nrf1 signalling in microglia. However, the K105R or/and K139R mutants of Nrf1 counteracted the impact of PTS in the OGD/R-induced microglial injury model, which indicates that PTS treatment might be a promising strategy for ischaemia stroke therapy.

CONCLUSION

The HDAC3/Nrf1 pathway regulates the stability and function of Nrf1 in microglial activation and neuroinflammation, which may depend on the acetylation of the lysine 105 and 139 residues in Nrf1. This mechanism was first identified as a potential regulatory mechanism of PTS-based neuroprotection in our research, which may provide new insight into further translational applications of natural products such as PTS.

The Interplay of Carveol and All-Trans Retinoic Acid (ATRA) in Experimental Parkinson's Disease: Role of Inflammasome-Mediated Pyroptosis and Nrf2

Parkinson's disease (PD) is a debilitating and the second most common neurodegenerative disorder with a high prevalence. PD has a multifaceted etiology characterized by an altered redox state and an excessive inflammatory response. Extensive research has consistently demonstrated the role of the nuclear factor E2-related factor (Nrf2) and inflammasomes, notably NLRP3 in neurodegenerative diseases. In this study, our focus was on exploring the potential neuroprotective properties of carveol in Parkinson's disease. Our findings suggest that carveol may exhibit these effects through Nrf2 and by suppressing pyroptosis. Male albino mice were treated with carveol, and the animal PD model was induced through a single intranigral dose of 2 µg/2µl lipopolysaccharide (LPS). To further demonstrate the essential role of the Nrf2 pathway, we utilized all-trans retinoic acid (ATRA) to inhibit the Nrf2. Our finding showed the induction of pyroptosis as evidenced by increased levels of NLRP3 and other inflammatory mediators, including IL-1β, iNOS, p-NFKB, and apoptotic cell death indicated by positive fluoro Jade B (FJB) staining. Moreover, increased levels of lipid peroxides and reactive oxygen species indicated a significant rise in oxidative stress due to LPS. The administration of carveol mitigates oxidative stress and suppresses inflammatory pathways through the augmentation of intrinsic antioxidant defenses, primarily via the activation of the Nrf2. Conversely, ATRA reversed carveol protective effects by increasing FJB-positive cells, inflammatory and oxidative biomarkers. Taken together, our findings suggest that carveol mitigated LPS-induced Parkinson-like symptoms, partially through the activation of the Nrf2 and downregulation of pyroptosis notably NLRP3.

Timed sulfonylurea modulation improves locomotor and sensory dysfunction following spinal cord injury

Traumatic spinal cord injury (SCI) results in immediate tissue necrosis and delayed secondary expansion of neurological damage, often resulting in lifelong paralysis, neurosensory dysfunction, and chronic pain. Progressive hemorrhagic necrosis (PHN) and excessive excitation are the main sources of secondary neural injury. Recent approaches to attenuate PHN by glibenclamide can improve locomotor function after SCI. However, use of glibenclamide can exacerbate development of SCI-induced chronic pain by inhibiting KATP channels to increase neuronal excitation and glial activation. In this study, we explored a treatment strategy involving administration of glibenclamide, which suppresses PHN, and diazoxide, which protects against neuronal excitation and inflammation, at different time intervals following spinal cord contusion. Our goal was to determine whether this combined approach enhances both sensory and motor function. Contusive SCI was induced at spinal segment T10 in adult rats. We found that KATP channels opener, diazoxide, decreased the hyperexcitability of primary sensory neurons after SCI by electrophysiology. Timed application of glibenclamide and diazoxide following contusion significantly improved locomotor function and mitigated development of SCI-induced chronic pain, as shown by behavioral evidence. Finally, we found that timed application of glibenclamide and diazoxide attenuates the inflammatory activity in the spinal cord and increases the survival of spinal matters following SCI. These preclinical studies introduce a promising potential treatment strategy to address SCI-induced dysfunction.

Synthesis of Lipidated Ligands and Formulation of Glia-Specific LNPs for RNAi-Mediated BBB Protection

Pro-inflammatory polarization of microglia and astrocytes results in neuroinflammation and blood-brain barrier (BBB) disruption after a primary traumatic brain injury (TBI). Herein, we demonstrate that the dual-ligand functionalized lipid nanoparticles (AM31 LNPs) were actively and specifically internalized by microglia and astrocytes via mannose receptor (MR)- and adenosine receptor (AR)-mediated endocytosis, respectively, in a mouse model of TBI. Systemic administration of AM31 LNPs carrying siRNA against p65 resulted in internalization by the glial cells in the peri-infarct region and a robust knockdown of p65 at both mRNA and protein levels in these cells, leading to significant down-regulation of key pro-inflammatory cytokines and up-regulation of key anti-inflammatory cytokines. AM31 LNP-mediated silencing of p65 ameliorated TBI-induced BBB disruption. Our data proved that AM 31 LNP is a promising vehicle for RNA therapeutics for targeting microglia and astrocytes in neural disorder.

Identification of Potential Biomarkers for Patients with DWI-Negative Ischemic Stroke

Ischemic stroke is the leading cause of long-term disability in adults, accounting for 80% of stroke cases. Diffusion weighted imaging (DWI) examination is the main test for acute ischemic stroke, but in recent years, several studies have shown that some patients show negative DWI examination after the onset of ischemic stroke with symptoms of significant neurological deficits. In this study, we investigated potential biomarkers related to immune metabolism in the peripheral blood of DWI-negative versus DWI-positive patients after ischemic stroke and explored their possible regulatory processes in ischemic stroke. The datasets related to ischemic stroke were downloaded from the GEO database, immune-related genes and metabolism-related genes were obtained from the ImmPort database and MSigDB database, respectively, and immune-related differential genes were obtained based on immune scores using the algorithm of the R software package "GSVA." Candidate genes were selected based on intersections, hub genes were screened using the algorithm in Cytoscape software, and finally, GeneMANIA analysis, GSEA enrichment analysis, subcellular localization, gene transcription factor and gene-drug interaction networks, and disease correlation analyses were performed for the hub genes. Five hub genes (GART, TYMS, PPAT, CTPS1, and PAICS) were obtained by PPI network analysis and software analysis. Among them, PPAT and PAICS may be the real hub genes with consistent and significantly differentiated results from the discovery and validation sets. The functions of these hub genes may be related to pathways such as nucleotide biosynthetic processes. The constructed hub gene ceRNA network showed that hsa-10a-5p is the key miRNA connecting PAICS and multiple lncRNAs in this study. Differential genes related to immunity and metabolism in DWI-negative and DWI-positive patients after IS were identified using bioinformatics analysis, and their pathways and related TF-RNAs, miRNAs, and lncRNAs were identified. These genes may be considered effective targets for the diagnosis and treatment of ischemic stroke.

Advancing stroke recovery: unlocking the potential of cellular dynamics in stroke recovery

Stroke stands as a predominant cause of mortality and morbidity worldwide, and there is a pressing need for effective therapies to improve outcomes and enhance the quality of life for stroke survivors. In this line, effective efferocytosis, the clearance of apoptotic cells, plays a crucial role in neuroprotection and immunoregulation. This process involves specialized phagocytes known as "professional phagocytes" and consists of four steps: "Find-Me," "Eat-Me," engulfment/digestion, and anti-inflammatory responses. Impaired efferocytosis can lead to secondary necrosis and inflammation, resulting in adverse outcomes following brain pathologies. Enhancing efferocytosis presents a potential avenue for improving post-stroke recovery. Several therapeutic targets have been identified, including osteopontin, cysteinyl leukotriene 2 receptor, the µ opioid receptor antagonist β-funaltrexamine, and PPARγ and RXR agonists. Ferroptosis, defined as iron-dependent cell death, is now emerging as a novel target to attenuate post-stroke tissue damage and neuronal loss. Additionally, several biomarkers, most importantly CD163, may serve as potential biomarkers and therapeutic targets for acute ischemic stroke, aiding in stroke diagnosis and prognosis. Non-pharmacological approaches involve physical rehabilitation, hypoxia, and hypothermia. Mitochondrial dysfunction is now recognized as a major contributor to the poor outcomes of brain stroke, and medications targeting mitochondria may exhibit beneficial effects. These strategies aim to polarize efferocytes toward an anti-inflammatory phenotype, limit the ingestion of distressed but viable neurons, and stimulate efferocytosis in the late phase of stroke to enhance post-stroke recovery. These findings highlight promising directions for future research and development of effective stroke recovery therapies.

Comprehensive immune modulation mechanisms of Angong Niuhuang Wan in ischemic stroke: Insights from mass cytometry analysis

BACKGROUND

Angong Niuhuang Wan (AGNHW, ), is a classical medicinal formula in Traditional Chinese Medicine (TCM) that has been appreciated for its neuroprotective properties in ischemic cerebral injuries, yet its intricate mechanisms remain only partially elucidated.

AIMS

This study leverages advanced Mass cytometry (CyTOF) to analyze AGNHW's multifaceted immunomodulation effects in-depth, emphasizing previously underexplored areas.

RESULTS

AGNHW mitigated monocyte-derived macrophages (MoDM) infiltration in the brain, distinguishing its effects on those from microglia. While the vehicle group exhibited elevated inflammatory markers like CD4, CD8a, and CD44 in ischemic brains, the AGNHW-treated group attenuated their expressions, indicating AGNHW's potential to temper the post-ischemic inflammatory response. Systemically, AGNHW modulated fundamental immune cell dynamics, notably augmenting CD8+ T cells, B cells, monocytes, and neutrophil counts in the peripheral blood under post-stroke conditions. Intracellularly, AGNHW exhibited its targeted modulation of the signaling pathways, revealing a remarked inhibition of key markers like IκBα, indicating potential suppression of inflammatory responses in ischemic brain injuries.

CONCLUSION

This study offers a comprehensive portrait of AGNHW's immunomodulation effects on ischemic stroke, illuminating its dual sites of action-both cerebral and systemic-and its nuanced modulation of cellular and molecular dynamics.

HPGD: An Intermediate Player in Microglial Polarization and Multiple Sclerosis Regulated by Nr4a1

HPGD encodes 15-Hydroxyprostaglandin dehydrogenase catalyzing the decomposition of prostaglandin E2 and has not been reported in multiple sclerosis (MS). We previously found that Nr4a1 regulated microglia polarization and inhibited the progression of experimental autoimmune encephalomyelitis (EAE). Bioinformatics analysis suggested that HPGD might be regulated by Nr4a1. Therefore, this study aimed to explore the role of HPGD in microglia polarization and determine whether HPGD mediates the inhibition of EAE by Nr4a1. C57BL/6 mice were treated with MOG35-55 peptide to induce EAE. BV-2 cells were treated with LPS/IL-4 to induce M1/M2 polarization. We then analyzed the pathological changes of spinal cord tissue, detected the expression levels of M1/M2 genes in tissues and cells, and explored the effect of HPGD on PPARγ activation to clarify the role of HPGD in EAE. The interaction between HPGD and Nr4a1 was verified by ChIP and pull-down assay. HPGD was downregulated in the spinal cord of EAE mice and HPGD overexpression alleviated the progression of EAE. Experiments in vitro and in vivo revealed that HPGD inhibited M1 polarization, promoted M2 polarization and increased PPARγ-DNA complex level. Nr4a1 could bind to the promoter of HPGD and its overexpression increased HPGD level. HPGD overexpression (or knockdown) reversed the effect of Nr4a1 knockdown (or overexpression) on M1/2 polarization. HPGD is regulated by Nr4a1 and inhibits the progression of EAE through shifting the M1/M2 polarization and promoting the activation of PPARγ signaling pathway. This study provides potential targets and basis for the development of MS therapeutic drugs.

Exogenous Functional Mitochondria Derived from Bone Mesenchymal Stem Cells That Respond to ROS Can Rescue Neural Cells Following Ischemic Stroke

Background

Upon uptake by stressed cells, functional mitochondria can perform their normal functions, ultimately enhancing the survival of host cells. However, despite the promising results of this approach, there is still a lack of understanding of the specific relationship between nerve cells and functional mitochondria.

Methods

Functional mitochondria (F-Mito) were isolated from bone marrow-derived mesenchymal stem cells (BMSCs). The ability of microglia cells to internalize F-Mito was evaluated using a middle cerebral artery occlusion (MCAO) model in C57BL/6J mice and an oxygen-glucose deprivation/reoxygenation (OGD/R) cell model. After OGD/R and F-Mito treatment, the temporal dynamics of intracellular reactive oxygen species (ROS) levels were examined.The relationship between ROS levels and F-Mito uptake was assessed at the individual cell level using MitoSOX, Mitotracker, and HIF-1α labeling.

Results

Our findings indicate that microglia cells exhibit enhanced mitochondrial uptake compared to astrocytes. Furthermore, internalized F-Mito reduced ROS levels and HIF-1α levels. Importantly, we found that the ROS response in microglia cells following ischemia is a critical regulator of F-Mito internalization, and promoting autophagy in microglia cells might reduce the uptake of ROS and HIF-1α levels.

Conclusion

It is verified that F-Mito derived from BMSCs play a protective role in ischemia-reperfusion injury, as their weakening reduces microglial cell activation and alleviates neuroinflammation.

Microglia in Ischemic Stroke: Pathogenesis Insights and Therapeutic Challenges

Ischemic stroke is the most common type of stroke, which is the main cause of death and disability on a global scale. As the primary immune cells in the brain that are crucial for preserving homeostasis of the central nervous system microenvironment, microglia have been found to exhibit dual or even multiple effects at different stages of ischemic stroke. The anti-inflammatory polarization of microglia and release of neurotrophic factors may provide benefits by promoting neurological recovery at the lesion in the early phase after ischemic stroke. However, the pro-inflammatory polarization of microglia and secretion of inflammatory factors in the later phase of injury may exacerbate the ischemic lesion, suggesting the therapeutic potential of modulating the balance of microglial polarization to predispose them to anti-inflammatory transformation in ischemic stroke. Microglia-mediated signaling crosstalk with other cells may also be key to improving functional outcomes following ischemic stroke. Thus, this review provides an overview of microglial functions and responses under physiological and ischemic stroke conditions, including microglial activation, polarization, and interactions with other cells. We focus on approaches that promote anti-inflammatory polarization of microglia, inhibit microglial activation, and enhance beneficial cell-to-cell interactions. These targets may hold promise for the creation of innovative therapeutic strategies.

Age-Related Alterations in Immune Function and Inflammation: Focus on Ischemic Stroke

The aging of the global population poses significant scientific challenges. Moreover, the biological process of aging is the most significant risk factor for most chronic illnesses; therefore, understanding the molecular and cellular mechanisms underlying these aging-related challenges is crucial for extending the healthy lifespan of older individuals. Preventing brain aging remains a priority public health goal, and integrative and comprehensive aging analyses have revealed that immunosenescence is a potential cause of age-related brain damage and disease (e.g., stroke). Importantly, the neuroinflammatory and immune systems present two-way contact and thus can affect each other. Emerging evidence supports the numerous effects of immunosenescence- and inflammation-mediated immunity in neurologically injured brains. In this study, we briefly outline how aging alters the pathophysiology and transcriptional amplitude in patients who experienced stroke and then discuss how the immune system and its cellular components and molecular mechanisms are affected by age after stroke. Finally, we highlight emerging interventions with the potential to slow down or reduce aging and prevent stroke onset.

Astrocyte-Derived Extracellular Vesicles for Ischemic Stroke: Therapeutic Potential and Prospective

Stroke is a leading cause of death and disability in the world. Astrocytes are special glial cells within the central nervous system and play important roles in mediating neuroprotection and repair processes during stroke. Extracellular vesicles (EVs) are lipid bilayer particles released from cells that facilitate intercellular communication in stroke by delivering proteins, lipids, and RNA to target cells. Recently, accumulating evidence suggested that astrocyte-derived EVs (ADEVs) are actively involved in mediating numerous biological processes including neuroprotection and neurorepair in stroke and they are realized as an excellent therapeutic approach for treating stroke. In this review we systematically summarize the up-to-date research on ADEVs in stroke, and prospects for its potential as a novel therapeutic target for stroke. We also provide an overview of the effects and functions of ADEVs on stroke recovery, which may lead to developing clinically relevant therapies for stroke.

Pannexin1 Channel-Mediated Inflammation in Acute Ischemic Stroke

Emerging evidence suggests that inflammation mediated by the pannexin1 channel contributes significantly to acute ischemic stroke. It is believed that the pannexin1 channel is key in initiating central system inflammation during the early stages of acute ischemic stroke. Moreover, the pannexin1 channel is involved in the inflammatory cascade to maintain the inflammation levels. Specifically, the interaction of pannexin1 channels with ATP-sensitive P2X7 purinoceptors or promotion of potassium efflux mediates the activation of the NLRP3 inflammasome, triggering the release of pro-inflammatory factors such as IL-1 and IL-18, exacerbating and sustaining inflammation of brain. Also, increased release of ATP induced by cerebrovascular injury activates pannexin1 in vascular endothelial cells. This signal directs peripheral leukocytes to migrate into ischemic brain tissue, leading to an expansion of the inflammatory zone. Intervention strategies targeting pannexin1 channels may greatly alleviate inflammation after acute ischemic stroke to improve this patient population's clinical outcomes. In this review, we sought to summarize relevant studies on inflammation mediated by the pannexin1 channel in acute ischemic stroke and discussed the possibility of using brain organoid-on-a-chip technology to screen miRNAs that exclusively target the pannexin1 channel to provide new therapeutic measures for targeted regulation of pannexin1 channel to reduce inflammation in acute ischemic stroke.

Naodesheng Pills Ameliorate Cerebral Ischemia Reperfusion-Induced Ferroptosis via Inhibition of the ERK1/2 Signaling Pathway

Background

Ferroptosis plays a crucial role in the occurrence and development of cerebral ischemia-reperfusion (I/R) injury and is regulated by mitogen-activated protein kinase 1/2 (ERK1/2). In China, Naodesheng Pills (NDSP) are prescribed to prevent and treat cerebrosclerosis and stroke. However, the protective effects and mechanism of action of NDSP against cerebral I/R-induced ferroptosis remain unclear. We investigated whether NDSP exerts its protective effects against I/R injury by regulating ferroptosis and aimed to elucidate the underlying mechanisms.

Methods

The efficacy of NDSP was evaluated using a Sprague-Dawley rat model of middle cerebral artery occlusion and an in vitro oxygen-glucose deprivation/reoxygenation (OGD/R) model. Brain injury was assessed using 2,3,5-triphenyltetrazolium chloride (TTC), hematoxylin and eosin staining, Nissl staining, and neurological scoring. Western blotting was performed to determine the expression levels of glutathione peroxidase 4 (GPX4), divalent metal-ion transporter-1 (DMT1), solute carrier family 7 member 11 (SLC7A11), and transferrin receptor 1 (TFR1). Iron levels, oxidative stress, and mitochondrial morphology were also evaluated. Network pharmacology was used to assess the associated mechanisms.

Results

NDSP (1.08 g/kg) significantly improved cerebral infarct area, cerebral water content, neurological scores, and cerebral tissue damage. Furthermore, NDSP inhibited I/R- and OGD/R-induced ferroptosis, as evidenced by the increased protein expression of GPX4 and SLC7A11, suppression of TFR1 and DMT1, and an overall reduction in oxidative stress and Fe2+ levels. The protective effects of NDSP in vitro were abolished by the GPX4 inhibitor RSL3. Network pharmacology analysis revealed that ERK1/2 was the core target gene and that NDSP reduced the amount of phosphorylated ERK1/2.

Conclusion

NDSP exerts its protective effects against I/R by inhibiting cerebral I/R-induced ferroptosis, and this mechanism is associated with the regulation of ferroptosis via the ERK1/2 signaling pathway.

Lysophosphatidic Acid Receptor 1 Plays a Pathogenic Role in Permanent Brain Ischemic Stroke by Modulating Neuroinflammatory Responses

Lysophosphatidic acid receptor 1 (LPA1) plays a critical role in brain injury following a transient brain ischemic stroke. However, its role in permanent brain ischemic stroke remains unknown. To address this, we investigated whether LPA1 could contribute to brain injury of mice challenged by permanent middle cerebral artery occlusion (pMCAO). A selective LPA1 antagonist (AM152) was used as a pharmacological tool for this investigation. When AM152 was given to pMCAO-challenged mice one hour after occlusion, pMCAO-induced brain damage such as brain infarction, functional neurological deficits, apoptosis, and blood-brain barrier disruption was significantly attenuated. Histological analyses demonstrated that AM152 administration attenuated microglial activation and proliferation in injured brain after pMCAO challenge. AM152 administration also attenuated abnormal neuroinflammatory responses by decreasing expression levels of pro-inflammatory cytokines while increasing expression levels of anti-inflammatory cytokines in the injured brain. As underlying effector pathways, NF-κB, MAPKs (ERK1/2, p38, and JNKs), and PI3K/Akt were found to be involved in LPA1-dependent pathogenesis. Collectively, these results demonstrate that LPA1 can contribute to brain injury by permanent ischemic stroke, along with relevant pathogenic events in an injured brain.

Microglia-neuron-vascular interactions in ischemia

Cerebral ischemia is a devastating condition that results in impaired blood flow in the brain leading to acute brain injury. As the most common form of stroke, occlusion of cerebral arteries leads to a characteristic sequence of pathophysiological changes in the brain tissue. The mechanisms involved, and comorbidities that determine outcome after an ischemic event appear to be highly heterogeneous. On their own, the processes leading to neuronal injury in the absence of sufficient blood supply to meet the metabolic demand of the cells are complex and manifest at different temporal and spatial scales. While the contribution of non-neuronal cells to stroke pathophysiology is increasingly recognized, recent data show that microglia, the main immune cells of the central nervous system parenchyma, play previously unrecognized roles in basic physiological processes beyond their inflammatory functions, which markedly change during ischemic conditions. In this review, we aim to discuss some of the known microglia-neuron-vascular interactions assumed to contribute to the acute and delayed pathologies after cerebral ischemia. Because the mechanisms of neuronal injury have been extensively discussed in several excellent previous reviews, here we focus on some recently explored pathways that may directly or indirectly shape neuronal injury through microglia-related actions. These discoveries suggest that modulating gliovascular processes in different forms of stroke and other neurological disorders might have presently unexplored therapeutic potential in combination with neuroprotective and flow restoration strategies.

NEAT1 inhibits the angiogenic activity of cerebral arterial endothelial cells by inducing the M1 polarization of microglia through the AMPK signaling pathway

BACKGROUND

Enhancing angiogenesis may be an effective strategy to promote functional recovery after ischemic stroke. Inflammation regulates angiogenesis. Microglia are crucial cells that initiate inflammatory responses after various brain injuries. Long noncoding RNA nuclear paraspeckle assembly transcript 1 (NEAT1) plays a role in regulating brain injury. This study aimed to explore the effects of NEAT1-regulated microglial polarization on the neovascularization capacity of cerebrovascular endothelial cells and the underlying molecular regulatory mechanisms.

METHODS

Mouse cerebral arterial endothelial cells (mCAECs) were co-cultured with BV-2 cells in different groups using a Transwell system. NEAT1 expression levels were measured by fluorescence quantitative reverse transcription PCR. Levels of IL-1β, IL-6, TNF-α, Arg-1, IL-4, and IL-10 were determined using ELISA. Expression levels of CD86 and CD163 were detected by immunofluorescence. The neovascularization capacity of mCAECs was assessed using CCK-8, Transwell, Transwell-matrigel, and tube formation assays. Label-free quantification proteomics was carried out to identify differentially expressed proteins. Protein levels were measured by Western blotting.

RESULTS

NEAT1 overexpression induced M1 polarization in BV-2 cells, whereas NEAT1 knockdown blocked lipopolysaccharide-induced M1 polarization in microglia. NEAT1-overexpressing BV-2 cells suppressed the angiogenic ability of mCAECs, and NEAT1-knocking BV-2 cells promoted the angiogenic ability of mCAECs under lipopolysaccharide treatment. Label-free quantitative proteomic analysis identified 144 upregulated and 131 downregulated proteins that were induced by NEAT1 overexpression. The AMP-activated protein kinase (AMPK) signaling pathway was enriched in the Kyoto Encyclopedia of Genes and Genomes analysis of the differentially expressed proteins. Further verification showed that NEAT1 inactivated the AMPK signaling pathway. Moreover, the AMPK activator 5-aminoimidazole-4-carboxamide ribonucleotide reversed the effect of NEAT1 on BV-2 polarization and the regulatory effect of NEAT1-overexpressing BV-2 cells on the angiogenic ability of mCAECs.

CONCLUSIONS

NEAT1 inhibits the angiogenic activity of mCAECs by inducing M1 polarization of BV-2 cells through the AMPK signaling pathway. This study further clarified the impact and mechanism of NEAT1 on microglia and the angiogenic ability of cerebrovascular endothelial cells.

Rhoa/ROCK, mTOR and Secretome-Based Treatments for Ischemic Stroke: New Perspectives

Ischemic stroke triggers a complex cascade of cellular and molecular events leading to neuronal damage and tissue injury. This review explores the potential therapeutic avenues targeting cellular signaling pathways implicated in stroke pathophysiology. Specifically, it focuses on the articles that highlight the roles of RhoA/ROCK and mTOR signaling pathways in ischemic brain injury and their therapeutic implications. The RhoA/ROCK pathway modulates various cellular processes, including cytoskeletal dynamics and inflammation, while mTOR signaling regulates cell growth, proliferation, and autophagy. Preclinical studies have demonstrated the neuroprotective effects of targeting these pathways in stroke models, offering insights into potential treatment strategies. However, challenges such as off-target effects and the need for tissue-specific targeting remain. Furthermore, emerging evidence suggests the therapeutic potential of MSC secretome in stroke treatment, highlighting the importance of exploring alternative approaches. Future research directions include elucidating the precise mechanisms of action, optimizing treatment protocols, and translating preclinical findings into clinical practice for improved stroke outcomes.

The ins and outs of microglial cells in brain health and disease

Microglia are the brain's resident macrophages that play pivotal roles in immune surveillance and maintaining homeostasis of the Central Nervous System (CNS). Microglia are functionally implicated in various cerebrovascular diseases, including stroke, aneurysm, and tumorigenesis as they regulate neuroinflammatory responses and tissue repair processes. Here, we review the manifold functions of microglia in the brain under physiological and pathological conditions, primarily focusing on the implication of microglia in glioma propagation and progression. We further review the current status of therapies targeting microglial cells, including their re-education, depletion, and re-population approaches as therapeutic options to improve patient outcomes for various neurological and neuroinflammatory disorders, including cancer.

Dihydroergotamine protects against ischemic stroke by modulating microglial/macrophage polarization and inhibiting inflammation in mice

OBJECTIVES

The search for drugs that can protect the brain tissue and reduce nerve damage in acute ischemic stroke has emerged as a research hotspot. We investigated the potential protective effects and mechanisms of action of dihydroergotamine against ischemic stroke.

METHODS

C57BL/6 mice were subjected to middle cerebral artery occlusion (MCAO), and dihydroergotamine at a dose of 10 mg/kg/day was intraperitoneally injected for 14 days. Adhesive removal and beam walking tests were conducted 1, 3, 5, 7, 10, and 14 days after MCAO surgery. Thereafter, the mechanism by which dihydroergotamine regulates microglia/macrophage polarization and inflammation and imparts ischemic stroke protection was studied using enzyme-linked immunosorbent assay, immunofluorescence staining, and western blotting.

RESULTS

From the perspective of a drug repurposing strategy, dihydroergotamine was found to inhibit oxygen-glucose deprivation damage to neurons, significantly improve cell survival rate, and likely exert a protective effect on ischemic brain injury. Dihydroergotamine significantly improved neural function scores and survival rates and reduced brain injury severity in mice. Furthermore, dihydroergotamine manifests its protective effect on ischemic brain injury by reducing the expression of TNF-α and IL-1β in mouse ischemic brain tissue, inhibiting the polarization of microglia/macrophage toward the M1 phenotype and promoting polarization toward the M2 phenotype.

CONCLUSION

This study is the first to demonstrate the protective effect of dihydroergotamine, a first-line treatment for migraine, against ischemic nerve injury in vitro and in vivo.

Immune cells: potential carriers or agents for drug delivery to the central nervous system

Drug delivery systems (DDS) have recently emerged as a promising approach for the unique advantages of drug protection and targeted delivery. However, the access of nanoparticles/drugs to the central nervous system (CNS) remains a challenge mainly due to the obstruction from brain barriers. Immune cells infiltrating the CNS in the pathological state have inspired the development of strategies for CNS foundation drug delivery. Herein, we outline the three major brain barriers in the CNS and the mechanisms by which immune cells migrate across the blood-brain barrier. We subsequently review biomimetic strategies utilizing immune cell-based nanoparticles for the delivery of nanoparticles/drugs to the CNS, as well as recent progress in rationally engineering immune cell-based DDS for CNS diseases. Finally, we discuss the challenges and opportunities of immune cell-based DDS in CNS diseases to promote their clinical development.

Edaravone dexborneol promotes M2 microglia polarization against lipopolysaccharide-induced inflammation via suppressing TLR4/MyD88/NF-κB pathway

Edaravone dexborneol (ED) is a novel neuroprotective compound that consists of two active ingredients, edaravone and ( +)-borneol in a 4:1 ratio, which has been shown the anti-inflammatory properties in animal models of ischemic stroke, cerebral hemorrhage, and autoimmune encephalomyelitis. However, the effect of ED on the polarization of microglia in neuroinflammation has not been elucidated. This study was to investigate the effects of ED on the polarization of microglia induced by lipopolysaccharide (LPS) and potential mechanisms. BV-2 microglial cells were incubated with ED (100, 200, and 400 µM) for 2 h, followed by lipopolysaccharide (LPS, 1 µg/ml) for 12 h. The researchers used the Griess method, western blot, immunocytochemistry, and subcellular fractionation to assess the effects and potential mechanisms of ED on neuroinflammatory reactions. The expression of ROS and the activities of antioxidant enzymes (SOD, GPx, and CAT) in LPS-induced BV-2 cells were also measured using the DCFH-DA fluorescent probe and colorimetric methods, respectively. It was observed that ED significantly declined the levels of TLR4/NF-κB pathway-associated proteins (TLR4, MyD88, p65, p-p65, IκBα, p-IκBα, IKKβ, p-IKKβ) and therefore inhibited LPS-induced production of NO, IL-1β, and TNF-α. Moreover, ED markedly downregulated the M1 marker (iNOS) and upregulated the M2 marker (Arginase-1, Ym-1). In addition, ED also reduced ROS generation and enhanced GPx activity. ED induced the polarization of LPS-stimulated microglia from M1 to M2 against inflammation by negatively regulating the TLR4/MyD88/NF-κB signaling pathway. Additionally, ED performed antioxidative function by depleting the intracellular excessive ROS caused by LPS through the enhancement of the enzymatic activity of GPx. ED may be a potential agent to attenuate neuroinflammation via regulating the polarization of microglia.

A One-Stone-Two-Birds Strategy of Targeting Microbubbles with "Dual" Anti-Inflammatory and Blood-Brain Barrier "Switch" Function for Ischemic Stroke Treatment

Inflammation is considered to be the main target of the development of new stroke therapies. There are three key issues in the treatment of stroke inflammation: the first one is how to overcome the blood-brain barrier (BBB) to achieve drug delivery, the second one is how to select drugs to treat stroke inflammation, and the third one is how to achieve targeted drug delivery. In this study, we constructed hydrocortisone-phosphatidylserine microbubbles and combined them with ultrasound (US)-targeted microbubble destruction technology to successfully open the BBB to achieve targeted drug delivery. Phosphatidylserine on the microbubbles was used for its "eat me" effect to increase the targeting of the microvesicles. In addition, we found that hydrocortisone can accelerate the closure of the BBB, achieving efficient drug delivery while reducing the entry of peripheral toxins into the brain. In the treatment of stroke inflammation, it was found that hydrocortisone itself has anti-inflammatory effects and can also change the polarization of microglia from the harmful pro-inflammatory M1 phenotype to the beneficial anti-inflammatory M2 phenotype, thus achieving dual anti-inflammatory effects and enhancing the anti-inflammatory effects in ischemic areas after stroke, well reducing the cerebellar infarction volume by inhibiting the inflammatory response after cerebral ischemia. A confocal microendoscope was used to directly observe the polarization of microglial cells in living animal models for dynamic microscopic visualization detection showing the advantage of being closer to clinical work. Taken together, this study constructed a multifunctional targeted US contrast agent with the function of "one-stone-two-birds", which can not only "on-off" the BBB but also have "two" anti-inflammatory functions, providing a new strategy of integrated anti-inflammatory targeted delivery and imaging monitoring for ischemic stroke treatment.

Influence of the brain‑gut axis on neuroinflammation in cerebral ischemia‑reperfusion injury (Review)

Stroke, a debilitating cerebrovascular ailment, poses significant threats to human life and health. The intricate interplay between the gut‑brain‑microbiota axis (GBMA) and cerebral ischemia‑reperfusion has increasingly become a focal point of scientific exploration, emerging as a pivotal research avenue in stroke pathophysiology. In the present review, the authors delved into the nexus between the GBMA and neuroinflammation observed post‑stroke. The analysis underscored the pivotal roles of histone deacetylase 3 and neutrophil extracellular traps subsequent to stroke incidents. The influence of gut microbial compositions and their metabolites, notably short‑chain fatty acids and trimethylamine N‑oxide, on neuroinflammatory processes, was further elucidated. The involvement of immune cells, especially regulatory T‑cells, and the intricate signaling cascades including cyclic GMP‑AMP synthase/stimulator of interferon genes/Toll‑like receptor, further emphasized the complex regulatory mechanisms of GBMA in cerebral ischemia/reperfusion injury (CI/RI). Collectively, the present review offered a comprehensive perspective on the metabolic, immune and inflammatory modulations orchestrated by GBMA, augmenting the understanding of its role in neuroinflammation following CI/RI.

Electroacupuncture attenuates middle cerebral artery occlusion-induced learning and memory impairment by regulating microglial polarization in hippocampus

BACKGROUND

As a traditional medical therapy, electroacupuncture (EA) has been demonstrated to have beneficial effects on ischemic stroke-induced cognitive impairment. However, the underlying mechanism is largely unclear.

METHODS

Adult rats received occlusion of the middle cerebral artery and reperfusion (MCAO/R) to establish the ischemic stroke model. Morris water maze test was performed following EA stimulation at the GV20, PC6, and KI1 acupoints in rats to test the learning and memory ability. Western blot, immunofluorescent staining, and enzyme-linked immunosorbent assay were conducted to assess the cellular and molecular mechanisms.

RESULTS

EA stimulation attenuated neurological deficits. In the Morris water maze test, EA treatment ameliorated the MCAO/R-induced learning and memory impairment. Moreover, we observed that MCAO/R induced microglial activation and polarization in the ischemic hippocampus, whereas, EA treatment dampened microglial activation and inhibited M1 microglial polarization but enhanced M2 microglial polarization. EA treatment inhibited the increased expression of proinflammatory cytokines and enhanced the increased expression of anti-inflammatory cytokines. Finally, we found that EA treatment dampened microglial p38 mitogen-activated protein kinase (MAPK) phosphorylation.

CONCLUSION

Collectively, our data suggested that EA treatment ameliorated cognitive impairment induced by MCAO/R and the underlying mechanism may be p38-mediated microglia polarization and neuroinflammation.

Hypoxic postconditioning drives protective microglial responses and ameliorates white matter injury after ischemic stroke

BACKGROUND

Ischemic stroke (IS) is a cerebrovascular disease with high incidence and mortality. White matter repair plays an important role in the long-term recovery of neurological function after cerebral ischemia. Neuroprotective microglial responses can promote white matter repair and protect ischemic brain tissue.

AIMS

The aim of this study was to investigate whether hypoxic postconditioning (HPC) can promote white matter repair after IS, and the role and mechanism of microglial polarization in white matter repair after HPC treatment.

MATERIALS & METHODS

Adult male C57/BL6 mice were randomly divided into three groups: Sham group (Sham), MCAO group (MCAO), and hypoxic postconditioning group (HPC). HPC group were subjected to 45 min of transient middle cerebral artery occlusion (MCAO) immediately followed by 40 min of HPC.

RESULTS

The results showed that HPC reduced the proinflammatory level of immune cells. Furthermore, HPC promoted the transformation of microglia to anti-inflammatory phenotype on the third day after the procedure. HPC promoted the proliferation of oligodendrocyte progenitors and increased the expression of myelination-related proteins on the 14th day. On the 28th day, HPC increased the expression of mature oligodendrocytes, which enhanced myelination. At the same time, the motor neurological function of mice was restored.

DISCUSSION

During the acute phase of cerebral ischemia, the function of proinflammatory immune cells was enhanced, long-term white matter damage was aggravated, and motor sensory function was decreased.

CONCLUSION

HPC promotes protective microglial responses and white matter repair after MCAO, which may be related to the proliferation and differentiation of oligodendrocytes.

Electrolyte Imbalance and Neurologic Injury

Neurologic injury continues to be a debilitating worldwide disease with high morbidity and mortality. The systemic sequelae of a neural insult often lead to prolonged hospital stays and challenging nutritional demands that contribute to poorer prognoses. Clinical management of a given condition should prioritize preserving the homeostatic parameters disrupted by inflammatory response cascades following the primary insult. This focused review examines the reciprocal relationship between electrolyte disturbance and neurologic injury. A prolonged electrolyte imbalance can significantly impact morbidity and mortality in neurologic injuries. A detailed overview of the major electrolytes and their physiologic, iatrogenic, and therapeutic implications are included. The pathophysiology of how dysnatremias, dyskalemias, dyscalcemias, and dysmagnesemias occur and the symptoms they can induce are described. The manifestations in relation to traumatic brain injury, status epilepticus, and acute ischemic stroke are addressed. Each type of injury and the strength of its association with a disruption in either sodium, potassium, calcium, or magnesium is examined. The value of supplementation and replacement is highlighted with an emphasis on the importance of early recognition in this patient population. This review also looks at the current challenges associated with correcting imbalances in the setting of different injuries, including the relevant indications and precautions for some of the available therapeutic interventions. Based on the findings of this review, there may be a need for more distinct clinical guidelines on managing different electrolyte imbalances depending on the specified neurologic injury. Additional research and statistical data on individual associations between insult and imbalance are needed to support this potential future call for context-based protocols.

The Impact of Juvenile Microglia Transcriptomics on the Adult Brain Regeneration after Cerebral Ischemia

Microglial cells play a pivotal role in the brain's health and operation through all stages of life and in the face of illness. The contributions of microglia during the developmental phase of the brain markedly contrast with their contributions in the brain of adults after injury. Enhancing our understanding of the pathological mechanisms that involve microglial activity in brains as they age and in cerebrovascular conditions is crucial for informing the creation of novel therapeutic approaches. In this work we provide results on microglia transcriptomics in the juvenile vs injured adult brain and its impact on adult brain regeneration after cerebral ischemia. During fetal brain development, microglia cells are involved in gliogenesis, angiogenesis, axonal outgrowth, synaptogenesis, neurogenesis and synaptic reorganization by engulfing neuronal extensions. Within the mature, intact brain, microglial cells exhibit reduced movement of their processes in response to minimal neuronal activity, while they continuously monitor their surroundings and clear away cellular debris. Following a stroke in the adult brain, inflammation, neurodegeneration, or disruptions in neural equilibrium trigger alterations in both the genetic blueprint and the structure and roles of microglia, a state often described as "activated" microglia. Such genetic shifts include a notable increase in the pathways related to phagosomes, lysosomes, and the presentation of antigens, coupled with a rise in the expression of genes linked to cell surface receptors. We conclude that a comparison of microglia transcriptomic activity during brain development and post-stroke adult brain might provide us with new clues about how neurodegeneration occurs in the adult brain. This information could very useful to develop drugs to slow down or limit the post-stroke pathology and improve clinical outcome.

Jasminoidin reduces ischemic stroke injury by regulating microglia polarization via PASK-EEF1A1 axis

Jasminoidin (JAS) can alleviate ischemic stroke (IS) injury, but its molecular mechanism remains undefined. The polarization of microglia affects IS process. This research is powered to probe whether the molecular mechanism of JAS for IS treatment is coupled with microglia polarization. IS modeling in mice was accomplished by middle cerebral artery occlusion (MCAO) and model mice were injected with 25 and 50 mg/mL JAS, followed by determination of infarct volume, brain water content, and histological changes in mouse brains. The microglia modeling was performed by 1-h oxygen-glucose deprivation and 24-h reoxygenation. Oxygen-glucose deprivation/reoxygenation (OGD/R)-induced microglia were treated with JAS and transfected with Per-Arnt-Sim kinase (PASK)-overexpressing plasmid, subsequent to which cell viability and lactate dehydrogenase (LDH) level were determined. The mRNA or protein expressions of examined genes in microglia and brain tissues were detected by quantitative real-time polymerase chain reaction or western blot. MCAO-induced massive infarction, edema, and injury in mouse brain tissues, upregulated interleukin-1 beta (IL-1β), FcγRIIB (CD32), tumor necrosis factor alpha (TNF-α), PASK, p-eukaryotic elongation factor 1A1 (EEF1A1), and p-EEF1A1/EEF1A1 levels, but downregulated mannose receptor 1 (CD206), arginase-1 (Arg-1) and interleukin-10 (IL-10), and EEF1A1 expressions, which was reversed by JAS. OGD/R treatment decreased microglial viability as well as expressions of CD206, Arg-1, IL-10, and EEF1A1, yet increased cytotoxicity and levels of IL-1β, CD32, TNF-α, PASK, p-EEF1A1, and p-EEF1A1/EEF1A1, which was reversed by JAS. PASK overexpression reversed the effects of JAS on microglia. JAS reduces IS injury by regulating microglia polarization via PASK-EEF1A1 axis.

Astrocyte-targeted siRNA delivery by adenosine-functionalized LNP in mouse TBI model

Traumatic brain injury (TBI) induces pro-inflammatory polarization of astrocytes and causes secondary disruption of the blood-brain barrier (BBB) and brain damage. Herein, we report a successful astrocyte-targeted delivery of small interfering RNA (siRNA) by ligand functionalized lipid nanoparticles (LNPs) formulated from adenosine-conjugated lipids and a novel ionizable lipid (denoted by Ad4 LNPs). Systemic administration of Ad4 LNPs carrying siRNA against TLR4 to the mice TBI model resulted in the specific internalization of the LNPs by astrocytes in the vicinity of damaged brain tissue. A substantial knockdown of TLR4 at both mRNA and protein levels in the brain was observed, which led to a significant decrease of key pro-inflammatory cytokines and an increase of key anti-inflammatory cytokines in serum. Dye leakage measurement suggested that the Ad4-LNP-mediated knockdown of TLR4 attenuated the TBI-induced BBB disruption. Together, our data suggest that Ad4 LNP is a promising vehicle for astrocyte-specific delivery of nucleic acid therapeutics.

Metabolic reprogramming regulates microglial polarization and its role in cerebral ischemia reperfusion

The brain is quite sensitive to changes in energy supply because of its high energetic demand. Even small changes in energy metabolism may be the basis of impaired brain function, leading to the occurrence and development of cerebral ischemia/reperfusion (I/R) injury. Abundant evidence supports that metabolic defects of brain energy during the post-reperfusion period, especially low glucose oxidative metabolism and elevated glycolysis levels, which play a crucial role in cerebral I/R pathophysiology. Whereas research on brain energy metabolism dysfunction under the background of cerebral I/R mainly focuses on neurons, the research on the complexity of microglia energy metabolism in cerebral I/R is just emerging. As resident immune cells of the central nervous system, microglia activate rapidly and then transform into an M1 or M2 phenotype to correspond to changes in brain homeostasis during cerebral I/R injury. M1 microglia release proinflammatory factors to promote neuroinflammation, while M2 microglia play a neuroprotective role by secreting anti-inflammatory factors. The abnormal brain microenvironment promotes the metabolic reprogramming of microglia, which further affects the polarization state of microglia and disrupts the dynamic equilibrium of M1/M2, resulting in the aggravation of cerebral I/R injury. Increasing evidence suggests that metabolic reprogramming is a key driver of microglial inflammation. For example, M1 microglia preferentially produce energy through glycolysis, while M2 microglia provide energy primarily through oxidative phosphorylation. In this review, we highlight the emerging significance of regulating microglial energy metabolism in cerebral I/R injury.

Regulation of oxygen-glucose deprivation/reperfusion-induced inflammatory responses and M1-M2 phenotype switch of BV2 microglia by lobetyolin

To elucidate the protective mechanism of lobetyolin on oxygen-glucose deprivation/reperfusion (OGD/R)-induced damage in BV2 microglial cells. The OGD/R model was established using a chemical modeling method to simulate in vivo brain ischemia in lobetyolin-pretreated BV2 cells. The optimum lobetyolin dosage, chemical concentration, and OGD/R modeling duration were screened. The changes in cell morphology were observed, and the levels of immune response-related factors, including tumor necrosis factor-α (TNF-α), interleukin-6, inducible nitric oxide synthase (iNOS), and cluster of differentiation (CD)206, were detected using the enzyme-linked immunosorbent assay. The expression of chemokine-like-factor-1 (CKLF1), hypoxia-inducible factor (HIF)-1α, TNF-α, and CD206, was detected using western blotting. The gene expression of M1 and M2 BV2 phenotype markers was assessed using quantitative polymerase chain reaction (qPCR). The localization of M1 and M2 BV2 markers was detected using immunofluorescence analysis. The results showed that lobetyolin could protect BV2 cells from OGD/R-induced damage. After OGD/R, CKLF1/C-C chemokine receptor type 4 (CCR4) levels increased in BV2 cells, whereas the CKLF1/CCR4 level was decreased due to lobetyolin pretreatment. Additionally, BV2 cells injured with OGD/R tended to be M1 type, but lobetyolin treatment shifted the phenotype of BV2 cells from M1 type to M2 type. Lobetyolin decreased the expression of TNF-α and HIF-1α but increased the expression of transforming growth factor-β (TGF-β) in BV2 cells, indicating a dose-effect relationship. The qPCR results showed that lobetyolin decreased the expression of CD16, CD32, and iNOS at the gene level and increased the expression of C-C-chemokine ligand-22 and TGF-β. The immunofluorescence analysis showed that lobetyolin decreased CD16/CD32 levels and increased CD206 levels. Lobetyolin can protect BV2 cells from OGD/R-induced damage by regulating the phenotypic polarization of BV2 and decreasing inflammatory responses. Additionally, CKLF1/CCR4 may participate in regulating lobetyolin-induced polarization of BV2 cells via the HIF-1α pathway.

CircPTP4A2 Promotes Microglia Polarization in Cerebral Ischemic Stroke via miR-20b-5p/YTHDF1/TIMP2 Axis

Activated microglia play dual roles in ischemic stroke (IS) according to its polarization states. Herein, we investigated the function of circPTP4A2 in regulating microglia polarization in IS. IS models were established by MACO/R and OGD/R treatment. TTC staining was employed to detect cerebral infarct size. Cell vitality was measured using CCK-8 assay. CD16 and CD206 levels were examined using flow cytometry. The interactions between circPTP4A2, miR-20b-5p, and YTHDF1 were analyzed by dual-luciferase reporter gene, RIP, or RNA pull-down assays. circPTP4A2 was upregulated in IS patients. circPTP4A2 knockdown alleviated MCAO/R-induced cerebral injury in mice. circPTP4A2 knockdown promoted microglia M2 polarization after OGD/R. circPTP4A2 promoted YTHDF1 expression by sponging miR-20b-5p. The promoting effect of circPTP4A2 knockdown on microglia M2 polarization was abrogated by miR-20b-5p inhibition. YTHDF1 activated the NF-κB pathway by increasing TIMP2 mRNA stability and expression. circPTP4A2 downregulation promoted microglia M2 polarization to inhibit IS development by regulating the miR-20b-5p/YTHDF1/TIMP2/NF-κB axis.

Sertraline Pre-Treatment Attenuates Hemorrhagic Transformation Induced in Rats after Cerebral Ischemia Reperfusion via Down Regulation of Neuronal CD163: Involvement of M1/M2 Polarization Interchange and Inhibiting Autophagy

Cerebral ischemia reperfusion (I/R) is one of the neurovascular diseases which leads to severe brain deterioration. Haemorrhagic transformation (HT) is the main complication of ischemic stroke. It exacerbates by reperfusion, causing a more deleterious effect on the brain and death. The current study explored the protective effect of sertraline (Sert) against cerebral I/R in rats by inhibiting HT, together with the molecular pathways involved in this effect. Forty-eight wister male rats were divided into 4 groups: Sham, Sert + Sham, I/R, and Sert + I/R. The ischemic model was induced by bilateral occlusion of the common carotid artery for 20 min, then reperfusion for 24 h. Sertraline (20 mg/kg, p.o.) was administrated for 14 days before exposure to ischemia. Pre-treatment with Sert led to a significant attenuation of oxidative stress and inflammation. In addition, Sert attenuated phosphorylation of extracellular regulated kinases and nuclear factor kappa-p65 expression, consequently modulating microglial polarisation to M2 phenotype. Moreover, Sert prevented the hemorrhagic transformation of ischemic stroke as indicated by the notable decrease in neuronal expression of CD163, activity of Heme oxygenase-2 and matrix metalloproteinase-2 and 9 levels. In the same context, Sert decreased levels of autophagy and apoptotic markers. Furthermore, histological examination, Toluidine blue, and Prussian blue stain aligned with the results. In conclusion, Sert protected against cerebral I/R damage by attenuating oxidative stress, inflammation, autophagy, and apoptotic process. It is worth mentioning that our study was the first to show that Sert inhibited hemorrhagic transformation. The protective effect of sertraline against injury induced by cerebral ischemia reperfusion via inhibiting Hemorrhagic transformation.

Multi-target mechanism of Naoshuantong capsule for treatment of Ischemic stroke based on network pharmacology and molecular docking

BACKGROUND

Naoshuantong capsule (NST capsule) is a classic Chinese patent medicine, which can treat ischemic stroke (IS) and has good clinical efficacy. However, its pharmacological mechanism remains to be further explored in the treatment of IS.

METHODS

The bio-active components and potential targets of NST Capsules were obtained by ETCM and TCMSP databases. In addition, the related targets of IS were collected by Genecard, OMIM, DrugBank, TTD and DisGeNET databases. NST-IS common target was obtained by Venn platform. PPI network of NST-IS common target and the composition - target network diagram of NST Capsule were constructed by Cytoscape3.8.1. Finally, AutoDock was used for molecular docking.

RESULTS

265 targets were predicted from 32 active compounds in NST Capsule, 109 common targets were identified between NST Capsule and IS. The top 10 key targets of PPI network were ALB, TNF, TP53, VEGFA, CASP3, MYC, etc. Enrichment analysis showed that NST capsules treated IS mainly through lipid and atherosclerosis, fluid shear stress and atherosclerosis signaling pathways.

CONCLUSION

Through the methods of network pharmacology and molecular docking, this study clarified that NST capsules play a role in the treatment of IS, which is multi-target, multi-channel and multi-component regulation. This study further explored the pharmacological mechanism of NST capsule in the treatment of IS, which can provide some references for the subsequent research in the pharmacological mechanism of NST capsule.

Sirtuins as Potential Targets for Neuroprotection: Mechanisms of Early Brain Injury Induced by Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a prevalent cerebrovascular disease with significant global mortality and morbidity rates. Despite advancements in pharmacological and surgical approaches, the quality of life for SAH survivors has not shown substantial improvement. Traditionally, vasospasm has been considered a primary contributor to death and disability following SAH, but anti-vasospastic therapies have not demonstrated significant benefits for SAH patients' prognosis. Emerging studies suggest that early brain injury (EBI) may play a crucial role in influencing SAH prognosis. Sirtuins (SIRTs), a group of NAD + -dependent deacylases comprising seven mammalian family members (SIRT1 to SIRT7), have been found to be involved in neural tissue development, plasticity, and aging. They also exhibit vital functions in various central nervous system (CNS) processes, including cognition, pain perception, mood, behavior, sleep, and circadian rhythms. Extensive research has uncovered the multifaceted roles of SIRTs in CNS disorders, offering insights into potential markers for pathological processes and promising therapeutic targets (such as SIRT1 activators and SIRT2 inhibitors). In this article, we provide an overview of recent research progress on the application of SIRTs in subarachnoid hemorrhage and explore their underlying mechanisms of action.

Effect of resveratrol and combination of resveratrol and donepezil on the expression of microglial cells and astrocytes in Wistar albino rats of colchicine-induced Alzheimer's disease

Aim

The goal was to evaluate the effect of resveratrol (RS) and combination therapy of RS and donepezil (DPZ), on the numerical expression of microglial cells and astrocytes, in the frontal cortex, regions of the hippocampus in colchicine-induced Alzheimer's disease (AD) model.

Methods

The study involved male albino Wistar rats of three months, age and consisted of 6 groups, with six animals each. The immunohistochemical staining with mouse monoclonal anti-human CD 68 and mouse monoclonal anti-GFAP was performed to assess the number of microglial cells and astrocytes, respectively.

Results

AD group showed an increase in the number of microglia, and the numbers declined in the treatment groups, RS 10, RS 20, RS10/10 and DPZ + RS (p < 0.001). Astrocyte count was increased in the treatment groups in contrast to the AD group (p < 0.05). The DPZ + RS combination group revealed substantial elevation in the number of astrocytes and decreased microglial number among all the groups (p < 0.001).

Conclusion

RS administration has diminished the microglial number and elevated the number of astrocytes. The elevated reactive astrocytes have decreased the microglial population. However, the limitation of our study is utilizing the colchicine for the induction of neurodegeneration. Using the transgenic models of AD may give a better insight into the pathogenesis and effect of RS. Another limitation of this study is the administration of RS and DPZ through different routes. The prospects of this research include studying the probiotic nature of RS and the effect of RS in other neurodegenerative disorders.

Insulin-like growth factor 1 in heat stress-induced neuroinflammation: novel perspective about the neuroprotective role of chromium

Heat stress (HS) can cause a series of stress responses, resulting in numerous negative effects on the body, such as the diminished food intake, carcass quality and reproductive capacity. In addition to the negative effects on the peripheral system, HS leads to central nervous system (CNS) disorders given its toll on neuroinflammation. This neuroinflammatory process is mainly mediated by microglia and astrocytes, which are involved in the activation of glial cells and the secretion of cytokines. While the regulation of inflammatory signaling has a close relationship with the expression of heat shock protein 70 (Hsp70), HS-induced neuroinflammation is closely related to the activation of the TLR4/NF-κB pathway. Moreover, oxidative stress and endoplasmic reticulum (ER) stress are key players in the development of neuroinflammation. Chromium (Cr) has been widely shown to have neuroprotective effects in both humans and animals, despite the lack of mechanistic evidence. Evidence has shown that Cr supplementation can increase the levels of insulin-like growth factor 1 (IGF-1), a major neurotrophic factor with anti-inflammatory and antioxidant effects. This review highlights recent advances in the attenuating effects and potential mechanisms of Cr-mediated IGF-1 actions on HS-induced neuroinflammation, providing presently existing evidence supporting the neuroprotective role of Cr.

Potential regulatory effects of stem cell exosomes on inflammatory response in ischemic stroke treatment

The high incidence and disability rates of stroke pose a heavy burden on society. Inflammation is a significant pathological reaction that occurs after an ischemic stroke. Currently, therapeutic methods, except for intravenous thrombolysis and vascular thrombectomy, have limited time windows. Mesenchymal stem cells (MSCs) can migrate, differentiate, and inhibit inflammatory immune responses. Exosomes (Exos), which are secretory vesicles, have the characteristics of the cells from which they are derived, making them attractive targets for research in recent years. MSC-derived exosomes can attenuate the inflammatory response caused by cerebral stroke by modulating damage-associated molecular patterns. In this review, research on the inflammatory response mechanisms associated with Exos therapy after an ischemic injury is discussed to provide a new approach to clinical treatment.

Microglia in Alzheimer's disease: pathogenesis, mechanisms, and therapeutic potentials

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by protein aggregation in the brain. Recent studies have revealed the critical role of microglia in AD pathogenesis. This review provides a comprehensive summary of the current understanding of microglial involvement in AD, focusing on genetic determinants, phenotypic state, phagocytic capacity, neuroinflammatory response, and impact on synaptic plasticity and neuronal regulation. Furthermore, recent developments in drug discovery targeting microglia in AD are reviewed, highlighting potential avenues for therapeutic intervention. This review emphasizes the essential role of microglia in AD and provides insights into potential treatments.

Network pharmacology to explore the mechanism of scutellarin in the treatment of brain ischaemia and experimental verification of JAK2/STAT3 signalling pathway

Scutellarin is used to treat brain ischaemia. However, its underlying mechanism of action remains unclear. This study aimed to elucidate the potential mechanism of action of scutellarin in brain ischaemia through network pharmacology and experimental verification. The JAK2/STAT3 signalling pathway was identified and experimentally verified. Expression of JAK2/STAT3 signalling related proteins in TNC-1 astrocytes with BV-2 microglia-conditioned medium (CM), CM + lipopolysaccharide (LPS) (CM + L), and CM pretreated with scutellarin + LPS (CM + SL) was analysed by Western Blot and immunofluorescence staining. Expression levels of JAK2, p-JAK2, STAT3, and p-STAT3 were evaluated in astrocytes pre-treated with AG490. Middle cerebral artery occlusion (MCAO) in rats was performed in different experimental groups to detect expression of the above biomarkers. Network pharmacology suggested that the JAK2/STAT3 signalling pathway is one of the mechanisms by which scutellarin mitigates cerebral ischaemic damage. In TNC-1 astrocytes, p-JAK2 and p-STAT3 expression were significantly up-regulated in the CM + L group. Scutellarin promoted the up-regulation of various markers and AG490 neutralised the effect of scutellarin. In vivo, up-regulation of p-JAK2 and p-STAT3 after ischaemia is known. These results are consistent with previous reports. Scutellarin further enhanced this upregulation at 1, 3, and 7 d after MCAO. Scutellarin exerts its therapeutic effects on cerebral ischaemia by activating the astrocyte JAK2/STAT3 signalling, which provides a firm experimental basis for its clinical application.

Human umbilical cord blood mononuclear cells ameliorate ischemic brain injury via promoting microglia/macrophages M2 polarization in MCAO Rats

Cerebral infarction is one of the most prevalent cerebrovascular disorders. Microglia and infiltrating macrophages play a key role in regulating the inflammatory response after ischemic stroke. Regulation of microglia/macrophages polarization contributes to the recovery of neurological function in cerebral infarction. In recent decades, human umbilical cord blood mononuclear cells (hUCBMNCs) have been considered a potential therapeutic alternative. However, the mechanism of action is yet unclear. Our study aimed to explore whether hUCBMNCs treatment for cerebral infarction is via regulation of microglia/macrophages polarization. Adult male Sprague-Dawley rats were subjected to middle cerebral artery occlusion (MCAO) and were treated by intravenous routine with or without hUCBMNCs at 24 h following MCAO. We evaluated the therapeutic effects of hUCBMNCs on cerebral infarction by measuring animal behavior and infarct volume, and further explored the possible mechanisms of hUCBMNCs for cerebral infarction by measuring inflammatory factors and microglia/macrophages markers using Elisa and immunofluorescence staining, respectively. We found that administration with hUCBMNCs improved behavioral functions and reduced infarct volume. Rats treated with hUCBMNCs showed a significant reduction in the level of IL-6, and TNF-α and increased the level of IL-4 and IL-10 compared to those treated without hUCBMNCs. Furthermore, hUCBMNCs inhibited M1 polarization and promoted M2 polarization of microglia/macrophages after MCAO. We conclude that hUCBMNCs could ameliorate cerebral brain injury by promoting microglia/macrophages M2 polarization in MCAO Rats. This experiment provides evidence that hUCBMNCs represent a promising therapeutic option for ischemic stroke.

BMP7 Attenuates Neuroinflammation after Spinal Cord Injury by Suppressing the Microglia Activation and Inducing Microglial Polarization Via the STAT3 Pathway

Excessive activation of pro-inflammatory (M1) microglia phenotypes after spinal cord injury (SCI) disrupts tissue repair and increases the risk of secondary SCI. We previously reported that adeno-associated virus (AAV) mediated delivery of bone morphogenetic protein 7 (BMP7) promotes functional recovery after SCI by reducing oligodendrocyte loss and demyelination; however, little is known about the early effects of BMP7 in ameliorating neuroinflammation in the acute SCI phase. Herein, we demonstrate that treatment with recombinant human BMP7 (rhBMP7) suppresses the viability of LPS-induced HMC3 microglia cells and increases the proportion with the M2 phenotype. Consistently, in a rat SCI model, rhBMP7 decreases the activation of microglia and promotes M2 polarization. After rhBMP7 administration, the STAT3 signaling pathway was activated in LPS-induced HMC3 cells and microglia in spinal cord lesions. Furthermore, the levels of TNF-α and IL-1β were significantly decreased in cell culture supernatants, lesion sites of injured spinal cords, and cerebrospinal fluid circulation after rhBMP7 administration, thus reducing neuron loss in the injured spinal cord and promoting functional recovery after SCI. These results provide insight into the immediate early mechanisms by which BMP7 may ameliorate the inflammation response to secondary SCI.

Low-Intensity Focused Ultrasound Neuromodulation for Stroke Recovery: A Novel Deep Brain Stimulation Approach for Neurorehabilitation?

Stroke as the leading cause of adult long-term disability and has a significant impact on patients, society and socio-economics. Non-invasive brain stimulation (NIBS) approaches such as transcranial magnetic stimulation (TMS) or transcranial electrical stimulation (tES) are considered as potential therapeutic options to enhance functional reorganization and augment the effects of neurorehabilitation. However, non-invasive electrical and magnetic stimulation paradigms are limited by their depth focality trade-off function that does not allow to target deep key brain structures critically important for recovery processes. Transcranial ultrasound stimulation (TUS) is an emerging approach for non-invasive deep brain neuromodulation. Using non-ionizing, ultrasonic waves with millimeter-accuracy spatial resolution, excellent steering capacity and long penetration depth, TUS has the potential to serve as a novel non-invasive deep brain stimulation method to establish unprecedented neuromodulation and novel neurorehabilitation protocols. The purpose of the present review is to provide an overview on the current knowledge about the neuromodulatory effects of TUS while discussing the potential of TUS in the field of stroke recovery, with respect to existing NIBS methods. We will address and discuss critically crucial open questions and remaining challenges that need to be addressed before establishing TUS as a new clinical neurorehabilitation approach for motor stroke recovery.

Brain and blood single-cell transcriptomics in acute and subacute phases after experimental stroke

Cerebral ischemia triggers a powerful inflammatory reaction involving both peripheral leukocytes and brain resident cells. Recent evidence indicates that their differentiation into a variety of functional phenotypes contributes to both tissue injury and repair. However, the temporal dynamics and diversity of post-stroke immune cell subsets remain poorly understood. To address these limitations, we performed a longitudinal single-cell transcriptomic study of both brain and mouse blood to obtain a composite picture of brain-infiltrating leukocytes, circulating leukocytes, microglia and endothelium diversity over the ischemic/reperfusion time. Brain cells and blood leukocytes isolated from mice 2 or 14 days after transient middle cerebral artery occlusion or sham surgery were purified by FACS sorting and processed for droplet-based single-cell transcriptomics. The analysis revealed a strong divergence of post-ischemic microglia, macrophages, and neutrophils over time, while such diversity was less evident in dendritic cells, B, T and NK cells. Conversely, brain endothelial cells and brain associated-macrophages showed altered transcriptomic signatures at 2 days post-stroke, but low divergence from sham at day 14. Pseudotime trajectory inference predicted the in-situ longitudinal progression of monocyte-derived macrophages from their blood precursors into day 2 and day 14 phenotypes, while microglia phenotypes at these two time points were not connected. In contrast to monocyte-derived macrophages, neutrophils were predicted to be continuously de-novo recruited from the blood. Brain single-cell transcriptomics from both female and male aged mice did not show major changes in respect to young mice, but aged and young brains differed in their immune cell composition. Furthermore, blood leukocyte analysis also revealed altered transcriptomes after stroke. However, brain-infiltrating leukocytes displayed higher transcriptomic divergence than their circulating counterparts, indicating that phenotypic diversification into cellular subsets occurs within the brain in the early and the recovery phase of ischemic stroke. In addition, this resource report contains a searchable database https://anratherlab.shinyapps.io/strokevis/ to allow user-friendly access to our data. The StrokeVis tool constitutes a comprehensive gene expression atlas that can be interrogated at the gene and cell type level to explore the transcriptional changes of endothelial and immune cell subsets from mouse brain and blood after stroke.

Immunomodulation: The next target of mesenchymal stem cell-derived exosomes in the context of ischemic stroke

Ischemic stroke (IS) is the most prevalent form of brain disease, characterized by high morbidity, disability, and mortality. However, there is still a lack of ideal prevention and treatment measures in clinical practice. Notably, the transplantation therapy of mesenchymal stem cells (MSCs) has been a hot research topic in stroke. Nevertheless, there are risks associated with this cell therapy, including tumor formation, coagulation dysfunction, and vascular occlusion. Also, a growing number of studies suggest that the therapeutic effect after transplantation of MSCs is mainly attributed to MSC-derived exosomes (MSC-Exos). And this cell-free mediated therapy appears to circumvent many risks and difficulties when compared to cell therapy, and it may be the most promising new strategy for treating stroke as stem cell replacement therapy. Studies suggest that suppressing inflammation via modulation of the immune response is an additional treatment option for IS. Intriguingly, MSC-Exos mediates the inflammatory immune response following IS by modulating the central nervous system, the peripheral immune system, and immunomodulatory molecules, thereby promoting neurofunctional recovery after stroke. Thus, this paper reviews the role, potential mechanisms, and therapeutic potential of MSC-Exos in post-IS inflammation in order to identify new research targets.

Engineering an inhibitor-resistant human CSF1R variant for microglia replacement

Hematopoietic stem cell transplantation (HSCT) can replace endogenous microglia with circulation-derived macrophages but has high mortality. To mitigate the risks of HSCT and expand the potential for microglia replacement, we engineered an inhibitor-resistant CSF1R that enables robust microglia replacement. A glycine to alanine substitution at position 795 of human CSF1R (G795A) confers resistance to multiple CSF1R inhibitors, including PLX3397 and PLX5622. Biochemical and cell-based assays show no discernable gain or loss of function. G795A- but not wildtype-CSF1R expressing macrophages efficiently engraft the brain of PLX3397-treated mice and persist after cessation of inhibitor treatment. To gauge translational potential, we CRISPR engineered human-induced pluripotent stem cell-derived microglia (iMG) to express G795A. Xenotransplantation studies demonstrate that G795A-iMG exhibit nearly identical gene expression to wildtype iMG, respond to inflammatory stimuli, and progressively expand in the presence of PLX3397, replacing endogenous microglia to fully occupy the brain. In sum, we engineered a human CSF1R variant that enables nontoxic, cell type, and tissue-specific replacement of microglia.

miR-34b-3p Inhibition of eIF4E Causes Post-stroke Depression in Adult Mice

Post-stroke depression (PSD) is a serious and common complication of stroke, which seriously affects the rehabilitation of stroke patients. To date, the pathogenesis of PSD is unclear and effective treatments remain unavailable. Here, we established a mouse model of PSD through photothrombosis-induced focal ischemia. By using a combination of brain imaging, transcriptome sequencing, and bioinformatics analysis, we found that the hippocampus of PSD mice had a significantly lower metabolic level than other brain regions. RNA sequencing revealed a significant reduction of miR34b-3p, which was expressed in hippocampal neurons and inhibited the translation of eukaryotic translation initiation factor 4E (eIF4E). Furthermore, silencing eIF4E inactivated microglia, inhibited neuroinflammation, and abolished the depression-like behaviors in PSD mice. Together, our data demonstrated that insufficient miR34b-3p after stroke cannot inhibit eIF4E translation, which causes PSD by the activation of microglia in the hippocampus. Therefore, miR34b-3p and eIF4E may serve as potential therapeutic targets for the treatment of PSD.

The core of maintaining neuropathic pain: Crosstalk between glial cells and neurons (neural cell crosstalk at spinal cord)

BACKGROUND

Neuropathic pain (NP) caused by the injury or dysfunction of the nervous system is a chronic pain state accompanied by hyperalgesia, and the available clinical treatment is relatively scarce. Hyperalgesia mediated by pro-inflammatory factors and chemokines plays an important role in the occurrence and maintenance of NP.

DATA TREATMENT

Therefore, we conducted a systematic literature review of experimental NP (PubMed Medline), in order to find the mechanism of inducing central sensitization and explore the intervention methods of hyperalgesia caused by real or simulated injury.

RESULT

In this review, we sorted out the activation pathways of microglia, astrocytes and neurons, and the process of crosstalk among them. It was found that in NP, the microglia P2X4 receptor is the key target, which can activate the mitogen-activated protein kinase pathway inward and then activate astrocytes and outwardly activate neuronal tropomyosin receptor kinase B receptor to activate neurons. At the same time, activated neurons continue to maintain the activation of astrocytes and microglia through chemokines on CXCL13/CXCR5 and CX3CL1/CX3CR1. This crosstalk process is the key to maintaining NP.

CONCLUSION

We summarize the further research on crosstalk among neurons, microglia, and astrocytes in the central nervous system, elaborate the ways and connections of relevant crosstalk, and find potential crosstalk targets, which provides a reference for drug development and preclinical research.

Purpurogallin Reverses Neuronal Apoptosis and Enhances "M2" Polarization of Microglia Under Ischemia via Mediating the miR-124-3p/TRAF6/NF-κB Axis

Purpurogallin (PPG) has been demonstrated to exert an anti-inflammatory function in neurological diseases. This study aimed at investigating the role of PPG on microglial polarization post ischemic stroke as well as the underlying mechanism. Mouse hippocampal neurons HT-22 and microglial BV2 cells were treated by oxygen and glucose deprivation to simulate an in-vitro ischemia model. qRT-PCR and ELISA examined expression of cytokines in microglia. CCK8 and flow cytometry measured HT-22 cell viability and apoptosis, respectively. The levels of miR-124-3p and TRAF6/NF-κB were determined. A mouse cerebral ischemia model was set up using middle cerebral artery occlusion (MCAO) method. After being dealt with PPG, the neurological functions, brain edema, neuronal apoptosis, and microglia activation of the mice were evaluated. As suggested by the results, PPG transformed "M1" to "M2" polarization of BV2 cells, and abated HT-22 cell apoptosis. PPG enhanced the neurological functions, alleviated brain edema, and decreased neuroinflammatory responses, and neuronal apoptosis in the brain lesions of MCAO mice. Furthermore, PPG enhanced miR-124-3p and repressed the TRAF6/NF-κB pathway. miR-124-3p suppressed the TRAF6/NF-κB pathway by targeting TRAF6. Collectively, PPG alleviates ischemia-induced neuronal damage and microglial inflammation by modulating the miR-124-3p/TRAF6/NF-κB pathway.