STAT6/Arg1 promotes microglia/macrophage efferocytosis and inflammation resolution in stroke mice

Sirt5-mediated polarization and metabolic reprogramming of macrophage sustain brain function following ischemic stroke

Ischemic stroke has become the leading cause of morbidity and mortality in adults. Reperfusion may initiate inflammatory response and cause damage to brain. Macrophage is supposed to be the major contributor of neuroinflammation and immune response. Hypersuccinylation correlates with neuropathological process post cerebral ischemia, rendering the possibility of functional role of succinylation in regulating recovery from injury. Here we reported that ischemic stroke causes upregulation of global protein succinylation dramatically. Mechanically, Sirt5 expression is repressed upon ischemic stroke, which exerts a crucial role in orchestrating global protein succinylation level. Furthermore, deficiency of Sirt5 enhances infiltration, M1 polarization and metabolic programming of macrophage in response to stroke via succinylation of Pkm2. Physiologically, depletion of Sirt5 enlarges damage region of brain during stroke. Utilization of Sirt5 agonist resveratrol efficiently ameliorates the destructive effects induced by stroke, thereby supporting recovery from brain injury. Our study not only reveal a heretofore unrecognized mechanism underlying the relation between stroke and protein succinylation, but also shed light on clinical potential for management of stroke injury via targeting protein succinylation.

Microglial phagocytosis and regulatory mechanisms: Key players in the pathophysiology of depression

Depression is a globally prevalent emotional disorder with a complex pathophysiology. Microglia are resident immune cells in the central nervous system, playing crucial roles in regulating inflammation, synaptic plasticity, immune phagocytosis, and other functions, thereby exerting significant impacts on neuropsychiatric disorders like depression. Increasing research indicates that abnormal phagocytic function of microglia in the brain is involved in depression, showing excessive or insufficient phagocytosis in different states. Here, we have provided a review of the signaling molecules involved in microglial phagocytosis in depression, including "eat me" signals such as phosphatidylserine (PS), complement, and "don't eat me" signals such as CD47, CD200 and related receptors. Furthermore, we discuss the regulatory effects of existing pharmaceuticals and dietary nutrients on microglial phagocytosis in depression, emphasizing the need for tailored modulation based on the varying phagocytic states of microglia. This review aims to facilitate a deeper understanding of the role of microglial phagocytosis in depression and provide a roadmap for potential therapeutic strategies for depression targeting microglial phagocytosis.

DDR2 alleviates retinal vaso-obliteration and pathological neovascularization by modulating microglia M1/M2 phenotypic polarization in a mouse model of proliferative retinopathy

Retinopathy of prematurity (ROP), a leading cause of blindness in premature infants, is characterized by retinal vaso-obliteration during hyperoxia and pathological neovascularization (NV) in relative hypoxia phase. Current treatments, which focus on the late stages of pathological neovascularization, are associated with numerous side effects. Studies demonstrated that discoidin domain receptor 2 (DDR2), a collagen-binding receptor tyrosine kinase, inhibits the experimental choroidal neovascularization and participates in tumor angiogenesis. However, the role of DDR2 in ROP and underlying mechanisms is unclear. In this study, we initially found that DDR2 expressed during mouse physiological retinal vascular development and significantly decreased in vaso-obliteration phase followed by increase during pathological neovascularization phase in mouse oxygen-induced retinopathy (OIR) model. Early upregulation of DDR2 before hyperoxia attenuates oxygen-induced vaso-obliteration, reduces pathological neovascularization, and promotes retinal vascular maturation. Additionally, DDR2 upregulation increased the number of microglia around retinal blood vessels and induced anti-inflammatory M2 polarization. Furthermore, the STAT6/TGF-β signaling pathway suppressed during hyperoxia was activated after DDR2 upregulation. In conclusion, DDR2 attenuated vaso-obliteration and inhibited pathological neovascularization by switching the microglia polarization from M1 to M2 phenotype via the STAT6/TGF-β signaling pathway in OIR. This suggests that DDR2 could be a novel target for the early treatment of ROP.

The Impact of VEGF-C-Induced Dural Lymphatic Vessel Growth on Ischemic Stroke Pathology

Timely relief of edema and clearance of waste products, as well as promotion of anti-inflammatory immune responses, reduce ischemic stroke pathology, and attenuate harmful long-term effects post-stroke. The discovery of an extensive and functional lymphatic vessel system in the outermost meningeal layer, dura mater, has opened up new possibilities to facilitate post-stroke recovery by inducing dural lymphatic vessel (dLV) growth via a single injection of a vector encoding vascular endothelial growth factor C (VEGF-C). In the present study, we aimed to improve post-stroke outcomes by inducing dLV growth in mice. We injected mice with a single intracerebroventricular dose of adeno-associated viral particles encoding VEGF-C before subjecting them to transient middle cerebral artery occlusion (tMCAo). Behavioral testing, Gadolinium (Gd) contrast agent-enhanced magnetic resonance imaging (MRI), and immunohistochemical analysis were performed to define the impact of VEGF-C on the post-stroke outcome. VEGF-C improved stroke-induced behavioral deficits, such as gait disturbances and neurological deficits, ameliorated post-stroke inflammation, and enhanced an alternative glial immune response. Importantly, VEGF-C treatment increased the drainage of brain interstitial fluid (ISF) and cerebrospinal fluid (CSF), as shown by Gd-enhanced MRI. These outcomes were closely associated with an increase in the growth of dLVs around the region where we observed increased vefgc mRNA expression within the brain, including the olfactory bulb, cortex, and cerebellum. Strikingly, VEGF-C-treated ischemic mice exhibited a faster and stronger Gd-signal accumulation in ischemic core area and an enhanced fluid outflow via the cribriform plate. In conclusion, the VEGF-C-induced dLV growth improved the overall outcome post-stroke, indicating that VEGF-C has potential to be included in the treatment strategies of post-ischemic stroke. However, to maximize the therapeutic potential of VEGF-C treatment, further studies on the impact of an enhanced dural lymphatic system at clinically relevant time points are essential.

Integrating Bulk RNA and Single-Cell Sequencing Data Unveils Efferocytosis Patterns and ceRNA Network in Ischemic Stroke

Excessive inflammatory response following ischemic stroke (IS) injury is a key factor affecting the functional recovery of patients. The efferocytic clearance of apoptotic cells within ischemic brain tissue is a critical mechanism for mitigating inflammation, presenting a promising avenue for the treatment of ischemic stroke. However, the cellular and molecular mechanisms underlying efferocytosis in the brain after IS and its impact on brain injury and recovery are poorly understood. This study explored the roles of inflammation and efferocytosis in IS with bioinformatics. Three Gene Expression Omnibus Series (GSE) (GSE137482-3 m, GSE137482-18 m, and GSE30655) were obtained from NCBI (National Center for Biotechnology Information) and GEO (Gene Expression Omnibus). Differentially expressed genes (DEGs) were processed for GSEA (Gene Set Enrichment Analysis), GO (Gene Ontology Functional Enrichment Analysis), and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analyses. Efferocytosis-related genes were identified from the existing literature, following which the relationship between Differentially Expressed Genes (DEGs) and efferocytosis-related genes was examined. The single-cell dataset GSE174574 was employed to investigate the distinct expression profiles of efferocytosis-related genes. The identified hub genes were verified using the dataset of human brain and peripheral blood sample datasets GSE56267 and GSE122709. The dataset GSE215212 was used to predict competing endogenous RNA (ceRNA) network, and GSE231431 was applied to verify the expression of differential miRNAs. At last, the middle cerebral artery (MCAO) model was established to validate the efferocytosis process and the expression of hub genes. DEGs in two datasets were significantly enriched in pathways involved in inflammatory response and immunoregulation. Based on the least absolute shrinkage and selection operator (LASSO) analyses, we identified hub efferocytosis-related genes (Abca1, C1qc, Ptx3, Irf5, and Pros1) and key transcription factors (Stat5). The scRNA-seq analysis showed that these hub genes were mainly expressed in microglia and macrophages which are the main cells with efferocytosis function in the brain. We then identified miR-125b-5p as a therapeutic target of IS based on the ceRNA network. Finally, we validated the phagocytosis and clearance of dead cells by efferocytosis and the expression of hub gene Abca1 in MCAO mice models.

Mechanism of adipose-derived stem cell-derived extracellular vesicles affecting macrophage efferocytosis by mediating ADAM17/MerTK in the apoptosis of tubular epithelial cells after sepsis-associated acute kidney injury

OBJECTIVE

This study explored the molecular mechanism of adipose-derived stem cell-derived extracellular vesicles (ADSC-EVs) improving post-sepsis-associated acute kidney injury (S-AKI) tubular epithelial cell (TEC) apoptosis by modulating ADAM17/MerTK-mediated macrophage efferocytosis.

METHODS

The S-AKI mouse model was established by caecal ligation and puncture and intravenously injected with ADSC-EVs. Mouse kidney macrophages were cultured with LPS, cultured with EVs while transfecting with oe-ADAM17 or si-MerTK, then incubated with Jurkat cells. Mouse serum urea and creatinine, and KIM-1, efferocytosis- and apoptosis-related protein, inflammatory factor, cytokine, and soluble MerTK (sMerTK) levels were determined using colorimetric assay, immunohistochemistry, Western blot, and ELISA. Renal tubular injury, TEC apoptosis, macrophage efferocytosis, and M1/M2 polarization levels were assessed via HE staining, TUNEL staining, immunofluorescence, and flow cytometry, respectively. In vivo validation experiments were conducted.

RESULTS

S-AKI mice displayed elevated levels of serum urea, creatinine, KIM-1, pro-inflammatory factors, pro-apoptotic proteins and ADAM17 protein, decreased anti-apoptotic protein and MerTK protein levels, and diminished M2 polarization. ADSC-EVs down-regulated ADAM17 and sMerTK, and increased cell membrane MerTK, macrophage recognition of apoptotic cells and efferocytosis, and M2 polarization in renal tissues of S-AKI mice and LPS-induced mouse renal macrophages, indicating that ADSC-EVs regulated ADAM17/MerTK-mediated macrophage efferocytosis and promoted M2 polarization. MerTK silencing partially reversed ADSC-EVs-regulated LPS-induced mouse renal macrophage efferocytosis and M2 polarization. In vivo, ADAM17 upregulation partly averted ADSC-EVs-regulated post-S-AKI TEC apoptosis in mouse renal tissues.

CONCLUSION

ADSC-EVs down-regulated sMerTK level and up-regulated macrophage membrane MerTK protein level by modulating ADAM17 to promote macrophage efferocytosis and ameliorate post-S-AKI TEC apoptosis and inflammation.

SORLA Orchestrates microglial dynamics for enhanced neuroprotection and recovery following ischemic stroke

This study identifies a novel function of Sortilin-related receptor with A-type repeats (SORLA), traditionally linked to Alzheimer's Disease (AD) as a high-risk gene and associated with neuronal function, in modulating microglial responses to ischemic stroke. We discovered that SORLA expression is significantly reduced in microglia following stroke, a change linked to increased brain injury and diminished neurological recovery. Utilizing SORLA knockout and overexpression models, we demonstrated its essential role in adjusting microglial inflammatory responses. Notably, microglial-specific overexpression of SORLA not only promoted anti-inflammatory actions and effective phagocytosis but also surpassed traditional concepts of microglial polarization. This overexpression mitigated brain damage and enhanced neurofunctional recovery post-stroke, highlighting the neuroprotective potential of SORLA. This breakthrough challenges the prevailing understanding the role of SORLA and opens new therapeutic possibilities for stroke recovery, indicating its wider relevance for neurodegenerative disease management.

Poliumoside Exhibits Neuroprotective Effects against Cerebral Ischemia-Reperfusion Injury by Relieving Microglia-Mediated Neuronal Damage and Astrocytic Activation

Excessive activation of microglia contributes to neuronal damage and astrocytic activation during cerebral ischemia and hypoxia. Poliumoside (Pol) is a caffeoylated phenylpropanoid glycoside with significant anti-inflammatory and antioxidant functions. However, whether Pol can mediate microglia-mediated neurotoxicity in the ischemic brain remains nebulous. Here, a cerebral ischemia-reperfusion injury (CI/RI) mouse model was conducted to investigate Pol's role in microglial activation and neurotoxicity. We found that Pol significantly reduced neurological deficits, cerebral infarction volume, and neuronal damage in the CI/RI mouse model. Pol inhibited proinflammatory cytokines and microglial and astrocytic activation, while enhancing anti-inflammatory cytokines. Mechanistically, Pol markedly suppressed Fstl1, NF-κB phosphorylation, and the Nlrp3-Asc-Caspase1 inflammasome. In the oxygen-glucose-deprivation (OGD)-mediated BV2 microglia, Fstl1 overexpression significantly enhanced microglial activation. The conditioned medium of Fstl1-overexpressed microglia promoted astrocytic activation and neuronal injuries. However, Pol treatment or NF-κB pathway inhibition reversed Fstl1-mediated effects. In conclusion, Pol restrained microglia-modulated neuroinflammation and neurotoxicity in the cerebral hypoxic-ischemic model by restraining the Fstl1-NF-κB pathway.

Necroptosis of hippocampal neurons in paclitaxel chemotherapy-induced cognitive impairment mediates microglial activation via TLR4/MyD88 signaling pathway

Background

Paclitaxel (PTX) chemotherapy frequently induces cognitive impairment, which is closely associated with two key pathological processes: necroptosis of hippocampal neurons and microglial polarization. Necroptotic neurons release damage-associated molecular patterns, triggering inflammatory responses. As the primary immune cells in the central nervous system, microglia can exhibit either pro-inflammatory or anti-inflammatory activity depending on their polarization state. However, the relationship between PTX-induced neuronal necroptosis and microglial activation remains unclear.

Methods

In this study, both in vivo and in vitro experiments were conducted. In vivo, an adult male C57BL/6N mouse model of PTX-induced cognitive impairment was established and divided into three groups: Veh (vehicle control), PTX (paclitaxel only), and P + N (paclitaxel with Nec-1 treatment). Necrostatin-1 (Nec-1), a specific inhibitor of RIPK1, was used to inhibit necroptosis. In vitro, HT22 cells were used to prepare necroptosis-conditioned medium, and BV-2 cells were treated with this medium. TAK-242, a TLR4 inhibitor, was used to explore the role of the TLR4/MyD88 signaling pathway. Immunofluorescence staining, western blot, and ELISA were employed to detect relevant markers and cytokines.

Results

The results demonstrated that PTX-induced necroptosis of hippocampal neurons activated microglia. Nec-1 effectively suppressed neuronal necroptosis and reduced M1 polarization of microglia. The TLR4/MyD88 signaling pathway was involved in microglial polarization induced by the necroptotic-conditioned medium of PTX-treated HT22 cells. TAK-242 significantly blocked the regulatory effect of PTX-induced neuronal necroptosis on BV-2 microglial polarization.

Conclusion

This study reveals that hippocampal neuron necroptosis activates microglia through the TLR4/MyD88 signaling pathway in PTX-induced cognitive impairment, promoting M1 polarization and neuroinflammation. Inhibiting necroptosis promotes M2 polarization and neuroprotection. These findings uncover a novel mechanism of PTX-induced cognitive impairment and suggest potential therapeutic targets.

Polylactic acid electrospun membranes coated with chiral hierarchical-structured hydroxyapatite nanoplates promote tendon healing based on a macrophage-homeostatic modulation strategy

Tendon injury is a common and challenging problem in the motor system that lacks an effective treatment, affecting daily activities and lowering the quality of life. Limited tendon regenerative capability and immune microenvironment dyshomeostasis are considered the leading causes hindering tendon repair. The chirality of biomaterials was proved to dictate immune microenvironment and dramatically affect tissue repair. Herein, chiral hierarchical structure hydroxylapatite (CHAP) nanoplates are innovatively synthesized for immunomodulatory purposes and further coated onto polylactic acid electrospinning membranes to achieve long-term release for tendon regeneration adaption. Notably, levorotatory-chiral HAP (L-CHAP) nanoplates rather than dextral-chiral or racemic-chiral exhibit good biocompatibility and bioactivity. In vitro experiments demonstrate that L-CHAP induces macrophage M2 polarization by enhancing macrophage efferocytosis, which alleviates inflammatory damage to tendon stem cells (TDSCs) through downregulated IL-17-NF-κB signaling. Meanwhile, L-CHAP-mediated macrophage efferocytosis also promotes TDSCs proliferation and tenogenic differentiation. By establishing a rat model of Achilles tendon injury, L-CHAP was demonstrated to comprehensively promoting tendon repair by enhancing macrophage efferocytosis and M2 polarization in vivo, finally leading to improvement of tendon ultrastructural and mechanical properties and motor function. This novel strategy highlights the role of L-CHAP in tendon repair and thus provides a promising therapeutic strategy for tendon injury.

Retinoic acid modulates peritoneal macrophage function and distribution to enhance antibacterial defense during inflammation

Background

Peritoneal macrophages, comprising large peritoneal macrophages (LPMs) and small peritoneal macrophages (SPMs), play a vital role in maintaining immune defenses during inflammation. However, the molecular mechanisms governing their responses, particularly the impact of retinoic acid (RA), remain poorly understood. This study aims to elucidate the role of RA in modulating macrophage function, distribution, and immune responses during bacterial infections.

Methods

A murine model of peritonitis was established using Escherichia coli expressing a tdTomato fluorescence marker. The effects of RA on macrophage phagocytic capacity, population dynamics, and transcriptomic profiles were assessed using immunofluorescence, flow cytometry, RNA sequencing, and quantitative PCR. Additionally, RA-loaded ZIF-8 nanoparticles were employed to investigate the sustained effects of RA delivery.

Results

RA significantly enhanced macrophage phagocytic activity, delayed functional decline, and promoted the recruitment of SPMs in the peritoneal cavity. Transcriptomic analysis revealed upregulation of leukocyte migration and cell adhesion pathways in RA-treated SPMs. RA treatment also induced distinct gene expression profiles in macrophage subpopulations, reflecting its role in immune modulation. Notably, RA-loaded ZIF-8 nanoparticles prolonged RA retention within macrophages, sustaining its effects.

Conclusion

RA enhances antibacterial defense by modulating macrophage activity, providing new insights into immune regulation. These findings underscore the therapeutic potential of RA and its nanoparticle formulations in managing bacterial infections and inflammation.

Alveolar macrophages polarization switch via α2-adrenoceptor activation ameliorates pulmonary inflammation following kidney ischemia reperfusion

PURPOSE

The present study aimed to explore the anti-inflammatory mechanism of dexmedetomidine (Dex), an α2-adrenoceptor (α2-AR) agonist, in renal ischemia-reperfusion (RIR)-induced acute lung injury (ALI).

METHODS

RIR was induced in C57BL/6J mice by bilateral renal pedicles occlusion for 60 min followed by 24 h of reperfusion. Mice were pretreated with Dex alone or in combination with atipamezole (Atip), an α2-AR antagonist. Pulmonary histopathological assessment, arterial blood gas analysis, cell count and multiple cytokine examination in bronchoalveolar lavage fluid (BALF), evaluation of the global inflammation status in lung tissue, and investigation of alveolar macrophage phenotypes were carried out. In vitro, the polarization of mouse alveolar macrophages (MH-S) treated with serum from normal or RIR mice was indirectly detected by quantitative polymerase chain reaction (qPCR).

RESULTS

The findings demonstrated that, in comparison to RIR animals, dexmedetomidine mitigated lung injury and remarkably promoted macrophage polarization towards an anti-inflammatory M2 phenotype in the pulmonary tissue. Concurrently, a reduction in inflammatory cell infiltration and levels of pro-inflammatory cytokines was observed. In vitro studies verified that dexmedetomidine directed MH-S towards the M2 phenotype after stimulation with RIR serum. However, these effects were mostly reversed following administration of atipamezole.

CONCLUSION

Dexmedetomidine alleviates renal ischemia-reperfusion-induced ALI by activating α2-adrenoceptor, thereby inducing macrophage polarization towards an anti-inflammatory phenotype and reducing pulmonary global inflammation.

Remote Organ Damage Induced by Stroke: Molecular Mechanisms and Comprehensive Interventions

Significance: Damage after stroke is not only limited to the brain but also often occurs in remote organs, including the heart, lung, liver, kidney, digestive tract, and spleen, which are frequently affected by complex pathophysiological changes. The organs in the human body are closely connected, and signals transmitted through various molecular substances could regulate the pathophysiological changes of remote organs. Recent Advances: The latest studies have shown that inflammatory response plays an important role in remote organ damage after stroke, and can aggravate remote organ damage by activating oxidative stress, sympathetic axis, and hypothalamic axis, and disturbing immunological homeostasis. Remote organ damage can also cause damage to the brain, aggravating inflammatory response and oxidative damage. Critical Issues: Therefore, an in-depth exploration of inflammatory and oxidative mechanisms and adopting corresponding comprehensive intervention strategies have become necessary to reduce damage to remote organs and promote brain protection. Future Directions: The comprehensive intervention strategy involves multifaceted treatment methods such as inflammation regulation, antioxidants, and neural stem cell differentiation. It provides a promising treatment alternative for the comprehensive recovery of stroke patients and an inspiration for future research and treatment. The various organs of the human body are interconnected at the molecular level. Only through comprehensive intervention at the molecular and organ levels can we save remote organ damage and protect the brain after stroke to the greatest extent. Antioxid. Redox Signal. 00, 000-000.

Role of efferocytosis in chronic pain -- From molecular perspective

The complex nature of pain pathophysiology complicates the establishment of objective diagnostic criteria and targeted treatments. The heterogeneous manifestations of pain stemming from various primary diseases contribute to the complexity and diversity of underlying mechanisms, leading to challenges in treatment efficacy and undesirable side effects. Recent evidence suggests the presence of apoptotic cells at injury sites, the distal dorsal root ganglia (DRG), spinal cord, and certain brain regions, indicating a potential link between the ineffective clearance of dead cells and debris and pain persistence. This review highlights recent research findings indicating that efferocytosis plays a significant yet often overlooked role in lesion expansion while also representing a potentially reversible impairment that could be targeted therapeutically to mitigate chronic pain progression. We examine recent advances into how efferocytosis, a process by which phagocytes clear apoptotic cells without triggering inflammation, influences pain initiation and intensity in both human diseases and animal models. This review summarizes that efferocytosis contributes to pain progression from the perspective of defective and inefficient efferocytosis and its subsequent secondary necrocytosis, cascade inflammatory response, and the shift of phenotypic plasticity and metabolism. Additionally, we investigate the roles of newly discovered genetic alterations or modifications in biological signaling pathways in pain development and chronicity, providing insights into innovative treatment strategies that modulate efferocytosis, which are promising candidates and potential avenues for further research in pain management and prevention.

Prolyl hydroxylase inhibitor desidustat improves stroke outcomes via enhancing efferocytosis in mice with chronic kidney disease

Patients with chronic kidney disease (CKD) are at a significantly increased risk of stroke and experience worse stroke outcomes and higher mortality. CKD exacerbates stroke risk and severity through a complex interplay of systemic inflammation, oxidative stress, and impaired clearance of uremic toxins, leading to neuroinflammation and microglial activation. Current acute ischemic stroke treatments, while effective in the general population, do not adequately address CKD-specific mechanisms, limiting their efficacy in this high-risk population. Prolyl hydroxylase domain (PHD) inhibitors have shown promise in treating anemia associated with CKD and may offer cerebroprotective benefits. However, the effects of PHD2 inhibition on long-term sensorimotor outcomes and the underlying mechanisms in mice with CKD remain largely unknown. Here, we investigated the impact of CKD on stroke severity and assessed the therapeutic potential of desidustat, a PHD inhibitor, in improving stroke outcomes. Using an adenine-induced CKD mouse model, we demonstrated that CKD exacerbated stroke-induced long-term sensorimotor deficits, increased neuroinflammation, and impaired microglial efferocytosis via dysregulation of the ADAM17-MerTK axis. Desidustat treatment in mice with CKD significantly improved long-term sensorimotor functional outcomes and reduced post-stroke neuroinflammation while enhancing microglial efferocytosis by reducing ADAM17 and enhancing microglial MerTK expression. In vitro studies using human-induced microglia-like cells further confirmed the ability of desidustat to enhance efferocytosis of apoptotic neurons by reducing the cleavage of MerTK. These findings suggest that desidustat may serve as a novel therapeutic strategy for improving stroke outcomes in patients with CKD, a population at high risk for stroke and poor functional recovery.

Microglia efferocytosis: an emerging mechanism for the resolution of neuroinflammation in Alzheimer's disease

Alzheimer's disease (AD) is a complex neurodegenerative disorder characterized by significant neuroinflammatory responses. Microglia, the immune cells of the central nervous system, play a crucial role in the pathophysiology of AD. Recent studies have indicated that microglial efferocytosis is an important mechanism for clearing apoptotic cells and cellular debris, facilitating the resolution of neuroinflammation. This review summarizes the biological characteristics of microglia and the mechanisms underlying microglial efferocytosis, including the factors and signaling pathways that regulate efferocytosis, the interactions between microglia and other cells that influence this process, and the role of neuroinflammation in AD. Furthermore, we explore the role of microglial efferocytosis in AD from three perspectives: its impact on the clearance of amyloid plaques, its regulation of neuroinflammation, and its effects on neuroprotection. Finally, we summarize the current research status on enhancing microglial efferocytosis to alleviate neuroinflammation and improve AD, as well as the future challenges of this approach as a therapeutic strategy for AD.

The origin and polarization of Macrophages and their role in the formation of the Pre-Metastatic niche in osteosarcoma

Osteosarcoma, a primary malignant bone tumor commonly found in adolescents, is highly aggressive, with a high rate of disability and mortality. It has a profound negative impact on both the physical and psychological well-being of patients. The standard treatment approach, comprising surgery and chemotherapy, has seen little improvement in patient outcomes over the past several decades. Once relapse or metastasis occurs, prognosis worsens significantly. Therefore, there is an urgent need to explore new therapeutic approaches. In recent years, the successful application of immunotherapy in certain cancers has demonstrated its potential in the field of cancer treatment. Macrophages are the predominant components of the immune microenvironment in osteosarcoma and represent critical targets for immunotherapy. Macrophages exhibit dual characteristics; while they play a key role in maintaining tumor-promoting properties within the microenvironment, such as inflammation, angiogenesis, and immune suppression, they also possess antitumor potential as part of the innate immune system. A deeper understanding of macrophages and their relationship with osteosarcoma is essential for the development of novel therapeutic strategies.

SIRPα modulates microglial efferocytosis and neuroinflammation following experimental subarachnoid hemorrhage via the SHP1/STAT6 axis

Subarachnoid hemorrhage induces extensive neuronal cell death, leading to the release of damage-associated molecular patterns (DAMPs). These DAMPs, along with hemoglobin and cell corpses, trigger localized inflammation. Signal regulatory protein alpha (SIRPα) plays a crucial role in efferocytosis by acting as a "don't eat-me" signal, modulating inflammation and tissue homeostasis. However, the precise function and regulatory mechanisms of SIRPα in efferocytosis remain unclear. Proteomic analysis of cerebrospinal fluid (CSF) reveals that SIRPα levels are significantly elevated in the CSF of SAH patients and correlate with clinical outcomes. In vivo and in vitro studies show that microglial knockdown of SIRPα promotes efferocytosis and attenuates neuroinflammation following SAH. SIRPα inhibits efferocytosis by recruiting and phosphorylating SHP1 and SHP2 through phosphorylation of four tyrosine residues in its cytoplasmic domain, with SHP1 playing a particularly critical role. Mutation of these tyrosine residues to non-phosphorylatable alanine residues enhances efferocytosis and reduces neuroinflammation in vitro. RNA-seq analysis suggests that this mutation upregulates the expression of "eat-me" signals, MerTK and CD36, and identifies STAT6 as a key transcription factor involved in this process. In conclusion, SIRPα plays a central role in regulating microglia efferocytosis and neuroinflammation after SAH via the SHP1/STAT6 axis. Targeting this pathway may provide a promising therapeutic approach for SAH.

Salidroside Derivative SHPL-49 Exerts Anti-Neuroinflammatory Effects by Modulating Excessive Autophagy in Microglia

The neuroinflammation triggered by cellular demise plays a pivotal role in ameliorating the injury associated with ischemic stroke, which represents a significant global burden of mortality and disability. The compound SHPL-49, a derivative of rhodioloside, was discovered by our research team and has previously demonstrated neuroprotective effects in rats with ischemic stroke. This study aimed to elucidate the underlying mechanisms of SHPL-49's protective effects. Preliminary investigations revealed that SHPL-49 effectively alleviates PMCAO-induced neuroinflammation. Further studies indicated that SHPL-49 downregulates the expression of the lysosomal protein LAMP-2 and reduces lysosomal activity, impeding the fusion of lysosomes and autophagosomes, thus inhibiting excessive autophagy and increasing the expression levels of the autophagy proteins LC3-II and P62. Furthermore, SHPL-49 effectively reverses the NF-κB nuclear translocation induced by the autophagy inducer rapamycin, significantly lowering the expression levels of the inflammatory factors IL-6, IL-1β, and iNOS. In a co-culture system of BV2 and PC12 cells, SHPL-49 enhanced PC12 cell viability by inhibiting excessive autophagy in BV2 cells and reducing the ratio of apoptotic proteins Bax and BCL-2. The overall findings suggest that SHPL-49 exerts its neuroprotective effects through the inhibition of excessive autophagy and the suppression of the NF-κB signaling pathway in microglia, thereby attenuating neuroinflammation.

Maresin-1 promotes neuroprotection and modulates metabolic and inflammatory responses in disease-associated cell types in preclinical models of multiple sclerosis

Multiple sclerosis (MS) is a prevalent inflammatory neurodegenerative disease in young people, causing neurological abnormalities and impairment. To investigate a novel therapeutic agent for MS, we observed the impact of maresin 1 (MaR1) on disease progression in a well-known, relapsing-remitting experimental autoimmune encephalomyelitis mouse model. Treatment with MaR1 accelerated inflammation resolution, reduced neurological impairment, and delayed disease development by reducing immune cell infiltration (CD4+IL-17+ and CD4+IFNγ+) into the central nervous system. Furthermore, MaR1 administration enhanced IL-10 production, primarily in macrophages and CD4+ cells. However, neutralizing IL-10 with an anti-IL-10 antibody eliminated the protective impact by MaR1 in relapsing-remitting experimental autoimmune encephalomyelitis model, implying the significance of IL-10 in MaR1 treatment. Metabolism has been recognized as a critical mediator of effector activity in many types of immune cells. In our investigation, MaR1 administration significantly repaired metabolic dysregulation in CD4+ cells, macrophages, and microglia in EAE mice. Furthermore, MaR1 treatment restored defective efferocytosis in treated macrophages and microglia. MaR1 also preserved myelin in EAE mice and regulated O4+ oligodendrocyte metabolism by reversing metabolic dysregulation via increased mitochondrial activity and decreased glycolysis. Overall, in a preclinical MS animal model, MaR1 therapy has anti-inflammatory and neuroprotective properties. It also induced metabolic reprogramming in disease-associated cell types, increased efferocytosis, and maintained myelination. Moreover, our data on patient-derived peripheral blood mononuclear cells substantiated the protective role of MaR1, expanding the therapeutic spectrum of specialized proresolving lipid mediators. Altogether, these findings suggest the potential of MaR1 as a novel therapeutic agent for MS and other autoimmune diseases.

Irisin reprograms microglia through activation of STAT6 and prevents cognitive dysfunction after surgery in mice

Postoperative cognitive dysfunction (POCD) is common in the aged population and associated with poor clinical outcomes. Irisin, an endogenous molecule that mediates the beneficial effects of exercise, has shown neuroprotective potential in several models of neurological diseases. Here we show that preoperative serum level of irisin is reduced in dementia patients over the age of 70. Comprehensive proteomics analysis reveals that deletion of irisin affects the nervous and immune systems, and reduces the expression of complement proteins. Systemically administered irisin penetrates the blood-brain barrier in mice, targets the microglial integrin αVβ5 receptor, activates signal transducer and activator of transcription 6 (STAT6), induces microglia reprogramming to the M2 phenotype, and improves immune microenvironment in LPS-induced neuroinflammatory mice. Finally, prophylactic administration of irisin prevents POCD-like behavior, particularly early cognitive dysfunction. Our findings provide new insights into the direct regulation of the immune microenvironment by irisin, and reveal that recombinant irisin holds great promise as a novel therapy for preventing POCD and other neuroinflammatory disorders. SUMMARY: Our findings reveal molecular and cellular mechanisms of irisin on neuroinflammation, and show that prophylactic administration of irisin prevents POCD-like behavior, particularly early cognitive dysfunction.

Macrophage corpses for immunoregulation and targeted drug delivery in treatment of collagen-induced arthritis mice

The role of pro-inflammatory macrophages (M1) in rheumatoid arthritis (RA) is significant, as they produce excessive cytokines. Targeting efferocytosis is a potential manner to repolarize M1 macrophages into pro-resolving M2 phenotype, which restores immune homeostasis by releasing anti-inflammatory mediators. In this study, liquid nitrogen-treated dead macrophages (DM) are employed to act as a dead cell-derived active targeted drug carrier for shikonin (SHK) and induce efferocytosis in M1 macrophages with the enhancement of SHK as an AMP-activated protein kinase (AMPK)-activator. The synergistic activation of AMPK leads to uncoupled protein 2 (UCP2) upregulation and reprograms M1 macrophages into M2 phenotypes by promoting oxidative phosphorylation. In the mouse model of collagen-induced arthritis, the intravenous administration of DM/SHK leads to a consistent transformation of M1 macrophages into the M2 phenotype within the infiltrative synovium. This transformation of macrophages results in the restoration of immune homeostasis in the synovium through an increase in the production of pro-resolving mediators. Additionally, it inhibits synovial proliferation and infiltration and provides protection against erosion of cartilage and bone. In summary, LNT-based DM serves as an active targeting drug carrier to M1 macrophages and also acts synergistically with SHK to target immunometabolism.

Energy metabolism in health and diseases

Energy metabolism is indispensable for sustaining physiological functions in living organisms and assumes a pivotal role across physiological and pathological conditions. This review provides an extensive overview of advancements in energy metabolism research, elucidating critical pathways such as glycolysis, oxidative phosphorylation, fatty acid metabolism, and amino acid metabolism, along with their intricate regulatory mechanisms. The homeostatic balance of these processes is crucial; however, in pathological states such as neurodegenerative diseases, autoimmune disorders, and cancer, extensive metabolic reprogramming occurs, resulting in impaired glucose metabolism and mitochondrial dysfunction, which accelerate disease progression. Recent investigations into key regulatory pathways, including mechanistic target of rapamycin, sirtuins, and adenosine monophosphate-activated protein kinase, have considerably deepened our understanding of metabolic dysregulation and opened new avenues for therapeutic innovation. Emerging technologies, such as fluorescent probes, nano-biomaterials, and metabolomic analyses, promise substantial improvements in diagnostic precision. This review critically examines recent advancements and ongoing challenges in metabolism research, emphasizing its potential for precision diagnostics and personalized therapeutic interventions. Future studies should prioritize unraveling the regulatory mechanisms of energy metabolism and the dynamics of intercellular energy interactions. Integrating cutting-edge gene-editing technologies and multi-omics approaches, the development of multi-target pharmaceuticals in synergy with existing therapies such as immunotherapy and dietary interventions could enhance therapeutic efficacy. Personalized metabolic analysis is indispensable for crafting tailored treatment protocols, ultimately providing more accurate medical solutions for patients. This review aims to deepen the understanding and improve the application of energy metabolism to drive innovative diagnostic and therapeutic strategies.

Detrimental influence of Arginase-1 in infiltrating macrophages on poststroke functional recovery and inflammatory milieu

Poststroke inflammation critically influences functional outcomes following ischemic stroke. Arginase-1 (Arg1) is considered a marker for anti-inflammatory macrophages, associated with the resolution of inflammation and promotion of tissue repair in various pathological conditions. However, its specific role in poststroke recovery remains to be elucidated. This study investigates the functional impact of Arg1 expressed in macrophages on poststroke recovery and inflammatory milieu. We observed a time-dependent increase in Arg1 expression, peaking at 7 d after photothrombotic stroke in mice. Cellular mapping analysis revealed that Arg1 was predominantly expressed in LysM-positive infiltrating macrophages. Using a conditional knockout (cKO) mouse model, we examined the role of Arg1 expressed in infiltrating macrophages. Contrary to its presumed beneficial effects, Arg1 cKO in LysM-positive macrophages significantly improved skilled forelimb motor function recovery after stroke. Mechanistically, Arg1 cKO attenuated fibrotic scar formation, enhanced peri-infarct remyelination, and increased synaptic density while reducing microglial synaptic elimination in the peri-infarct cortex. Gene expression analysis of fluorescence-activated single cell sorting (FACS)-sorted CD45low microglia revealed decreased transforming growth factor-β (TGF-β) signaling and proinflammatory cytokine activity in peri-infarct microglia from Arg1 cKO animals. In vitro coculture experiments demonstrated that Arg1 activity in macrophages modulates microglial synaptic phagocytosis, providing evidence for macrophage-microglia interaction. These findings present unique insights into the function of Arg1 in central nervous system injury and highlight an interaction between infiltrating macrophages and resident microglia in shaping the poststroke inflammatory milieu. Our study identifies Arg1 in macrophages as a potential therapeutic target for modulating poststroke inflammation and improving functional recovery.

Human herpesvirus-associated transposable element activation in human aging brains with Alzheimer's disease

INTRODUCTION

Human herpesvirus (HHV) has been linked to Alzheimer's disease (AD), but the underlying mechanisms remain unknown.

METHODS

We leveraged functional genomics data from Religious Orders Study or the Rush Memory and Aging Project (ROS/MAP) and Mount Sinai Brain Bank (MSBB) brain biobanks and single-cell RNA-sequencing data from HHV-infected forebrain organoids to investigate HHV-infection-associated transposable element (TE) dysregulation underlying AD etiologies.

RESULTS

We identified widespread TE dysregulation in HHV-positive human AD brains, including an astrocyte-specific upregulation of LINE1 subfamily TEs in HHV-positive human AD brains. We further pinpointed astrocyte-specific LINE1 upregulation that could potentially regulate target gene NEAT1 expression via long-range enhancer-promoter chromatin interactions. This LINE1 dysregulation can be partially reversed by the usage of anti-HHV drugs (valacyclovir and acyclovir) in a virus-infected human brain organoid model. Finally, we demonstrated that valacyclovir rescued tau-associated neuropathology and alleviated LINE1 activation in an experimental tau aggregation model.

DISCUSSION

Our analysis provides associations linking molecular, clinical, and neuropathological AD features with HHV infection, which warrants future clinical validation.

HIGHLIGHTS

Via analysis of bulk RNA-seq data in two large-scale human brain biobanks, ROS/MAP (n = 109 pathologically confirmed AD and n = 44 cognitively healthy controls) and MSBB (n = 284 AD and n = 150 cognitively healthy controls), we identified widespread TE activation in HHV-positive human AD brains and significantly positive associations of HHV RNA abundance with APOE4 genotype, Braak staging score, and CERAD score. We identified cell type-specific LINE1 upregulation in both microglia and astrocytes of human AD brains via long-range enhancer-promoter chromatin interactions on lncRNA nuclear enriched abundant transcript 1 (NEAT1). We determined that usage of valacyclovir and acyclovir was significantly associated with reduced incidence of AD in a large real-world patient database. Using the HEK293 tau P301S model and U2OS mt-Keima cell model, we determined that valacyclovir treatment rescued tau-associated neuropathology and alleviated activation of LINE1 with increased cellular autophagy-level mechanistically supported clinical benefits of valacyclovir in real-world patient data.

Matrix-Rigidity Cooperates With Biochemical Cues in M2 Macrophage Activation Through Increased Nuclear Deformation and Chromatin Accessibility

Macrophages encounter a myriad of biochemical and mechanical stimuli across various tissues and pathological contexts. Notably, matrix rigidity has emerged as a pivotal regulator of macrophage activation through mechanotransduction. However, the precise mechanisms underlying the interplay between mechanical and biochemical cues within the nuclear milieu remain elusive. Here We elucidate how the increased matrix rigidity drives macrophages to amplify alternatively-activated (M2 phenotype) signaling cooperatively with biochemical cues (e.g., IL4/13) through altered nuclear mechanics. We demonstrate that reconstructed podosome-like F-actins and contractility induce nucleus deformation, opening nuclear pores, which facilitates nuclear translocation of the key transcription factor STAT6. Furthermore, the altered nuclear mechanics increases chromatin accessibility induced by H3K9 methylation, particularly of M2-associated gene promoters. These cooperative events of the mechano-chemical signaling at the cytoskeletal-to-nuclear domains facilitate M2 transcriptional activation and cellular functions. We further evidence the rigidity-primed M2 macrophages are immunosuppressive and accumulated within stiffened tumors in patients. This study proposes a mechanism by which matrix mechanics crosstalks with biochemical signals to potentiate macrophage activation through nuclear mechanosensing and chromatin modifications, offering insights into macrophage mechanobiology and its therapeutic modulations.

Danhong injection modulates microglial polarization and neuroinflammation via the JUNB/NF-κB pathway in ischemic stroke

ETHNOPHARMACOLOGICAL RELEVANCE

Ischemic stroke (IS) is a leading cause of death and disability in China. Danhong Injection (DHI) is a traditional Chinese medicine preparation made from Salvia miltiorrhiza var. miltiorrhiza and Carthamus tinctoriusL. It is used for treating stroke in China with proven safety and efficacy. Microglia M1/M2 polarization is a key factor in IS inflammatory response. However, the key transcription factors that regulate microglia polarization are unknown. It is also not clear how DHI exerts its mechanism in the treatment of IS.

AIM OF THE STUDY

This research aimed to investigate the effect of DHI on microglial polarization and neuroinflammation associated with IS and to elucidate the underlying mechanisms, with an emphasis on the JUNB/NF-κB signaling pathway.

MATERIALS AND METHODS

An oxygen-glucose deprivation (OGD) damage cell model and a permanent middle cerebral artery occlusion (pMCAO) model in C57BL/6 mice were employed. Neurological deficits, cerebral infarct volume, and microglial activation were assessed. Non-targeted metabolomics analysis with UHPLC-QE-MS and molecular biology methods, including RT-qPCR and Western blot, were applied to investigate the mechanisms.

RESULTS

In vivo, DHI decreased inflammation, reduced brain damage, and enhanced neurological function. DHI also ameliorated microglial activation and OGD-induced apoptosis in vitro. Metabolomics analysis identified significant metabolic changes, particularly in amino acid metabolism. Additionally, DHI treatment decreased the upregulated mRNA levels of ASS1 and ASL after OGD, indicating an influence on the arginine biosynthesis pathway, which is crucial for microglial function. DHI modulated the M1 to M2 phenotypes of microglial polarization and regulated microglial polarization through the JUNB/NF-κB signaling pathway. This was confirmed by JUNB silencing experiments.

CONCLUSIONS

DHI exhibits neuroprotective effects via suppressing ASS1 through the JUNB/NF-κB pathway, promoting the M2 state of microglia, and lowering the expression of inflammatory cytokines. This research unveils the potential therapeutic target of JUNB for IS treatment and sheds light on the novel intervention mechanism of DHI in microglial cells.

Changes in border-associated macrophages after stroke: single-cell sequencing analysis

ABSTRACT

Border-associated macrophages are located at the interface between the brain and the periphery, including the perivascular spaces, choroid plexus, and meninges. Until recently, the functions of border-associated macrophages have been poorly understood and largely overlooked. However, a recent study reported that border-associated macrophages participate in stroke-induced inflammation, although many details and the underlying mechanisms remain unclear. In this study, we performed a comprehensive single-cell analysis of mouse border-associated macrophages using sequencing data obtained from the Gene Expression Omnibus (GEO) database (GSE174574 and GSE225948). Differentially expressed genes were identified, and enrichment analysis was performed to identify the transcription profile of border-associated macrophages. CellChat analysis was conducted to determine the cell communication network of border-associated macrophages. Transcription factors were predicted using the 'pySCENIC' tool. We found that, in response to hypoxia, border- associated macrophages underwent dynamic transcriptional changes and participated in the regulation of inflammatory-related pathways. Notably, the tumor necrosis factor pathway was activated by border-associated macrophages following ischemic stroke. The pySCENIC analysis indicated that the activity of signal transducer and activator of transcription 3 (Stat3) was obviously upregulated in stroke, suggesting that Stat3 inhibition may be a promising strategy for treating border-associated macrophages-induced neuroinflammation. Finally, we constructed an animal model to investigate the effects of border-associated macrophages depletion following a stroke. Treatment with liposomes containing clodronate significantly reduced infarct volume in the animals and improved neurological scores compared with untreated animals. Taken together, our results demonstrate comprehensive changes in border-associated macrophages following a stroke, providing a theoretical basis for targeting border-associated macrophages-induced neuroinflammation in stroke treatment.

Arginine metabolism in myeloid cells in health and disease

Metabolic flexibility is key for the function of myeloid cells. Arginine metabolism is integral to the regulation of myeloid cell responses. Nitric oxide (NO) production from arginine is vital for the antimicrobial and pro-inflammatory responses. Conversely, the arginase 1 (ARG1)-dependent switch between the branch of NO production and polyamine synthesis downregulates inflammation and promotes recovery of tissue homeostasis. Creatine metabolism is key for energy supply and proline metabolism is required for collagen synthesis. Myeloid ARG1 also regulates extracellular arginine availability and T cell responses in parasitic diseases and cancer. Cancer, surgery, sepsis and persistent inflammation in chronic inflammatory diseases, such as neuroinflammatory diseases or arthritis, are associated with dysregulation of arginine metabolism in myeloid cells. Here, we review current knowledge on arginine metabolism in different myeloid cell types, such as macrophages, neutrophils, microglia, osteoclasts, tumor-associated macrophages (TAMs), tumor-associated neutrophils (TANs) and myeloid-derived suppressor cells (MDSCs). A deeper understanding of the function of arginine metabolism in myeloid cells will improve our knowledge on the pathology of several diseases and may set the platform for novel therapeutic applications.

Extracellular cold-inducible RNA-binding protein in CNS injury: molecular insights and therapeutic approaches

Central nervous system (CNS) injuries, such as ischemic stroke (IS), intracerebral hemorrhage (ICH) and traumatic brain injury (TBI), are a significant global burden. The complex pathophysiology of CNS injury is comprised of primary and secondary injury. Inflammatory secondary injury is incited by damage-associated molecular patterns (DAMPs) which signal a variety of resident CNS cells and infiltrating immune cells. Extracellular cold-inducible RNA-binding protein (eCIRP) is a DAMP which acts through multiple immune and non-immune cells to promote inflammation. Despite the well-established role of eCIRP in systemic and sterile inflammation, its role in CNS injury is less elucidated. Recent literature suggests that eCIRP is a pleiotropic inflammatory mediator in CNS injury. eCIRP is also being evaluated as a clinical biomarker to indicate prognosis in CNS injuries. This review provides a broad overview of CNS injury, with a focus on immune-mediated secondary injury and neuroinflammation. We then review what is known about eCIRP in CNS injury, and its known mechanisms in both CNS and non-CNS cells, identifying opportunities for further study. We also explore eCIRP's potential as a prognostic marker of CNS injury severity and outcome. Next, we provide an overview of eCIRP-targeting therapeutics and suggest strategies to develop these agents to ameliorate CNS injury. Finally, we emphasize exploring novel molecular mechanisms, aside from neuroinflammation, by which eCIRP acts as a critical mediator with significant potential as a therapeutic target and prognostic biomarker in CNS injury.

Investigation of the Molecular Mechanism of Asthma in Meishan Pigs Using Multi-Omics Analysis

Asthma has been extensively studied in humans and animals, but the molecular mechanisms underlying asthma in Meishan pigs, a breed with distinct genetic and physiological characteristics, remain elusive. Understanding these mechanisms could provide insights into veterinary medicine and human asthma research. We investigated asthma pathogenesis in Meishan pigs through transcriptomic and metabolomic analyses of blood samples taken during autumn and winter. Asthma in Meishan pigs is related to inflammation, mitochondrial oxidative phosphorylation, and tricarboxylic acid (TCA) cycle disorders. Related genes include CXCL10, CCL8, CCL22, CCL21, OLR1, and ACKR1, while metabolites include succinic acid, riboflavin-5-phosphate, and fumaric acid. Transcriptomic sequencing was performed on panting and normal Meishan pigs, and differentially expressed genes underwent functional enrichment screening. Metabolomic analysis revealed differential metabolites and pathways between groups. Combined analyses indicated that lung inflammation is influenced by genetic, allergenic, and environmental factors disrupting oxidative phosphorylation in lung mitochondria, affecting the TCA cycle. Mitochondrial reactive oxygen species, glutathione S-transferases, arginase 1 and RORC in immune regulation, the Notch pathway, YPEL4 in cell proliferation, and MARCKS in airway mucus secretion play roles in asthma pathogenesis. This study highlights that many cytokines and signaling pathways contribute to asthma. Further studies are needed to elucidate their complex interactions.

Protective effects of berbamine against arginase-1 deficiency-induced injury in human brain microvascular endothelial cells

Endothelial cell dysfunction plays a crucial role in the early development of cerebral small vessel disease (CSVD). Arginase-1 (ARG1) is expressed in endothelial cells, and its deficiency may exacerbate cerebrovascular damage by increasing reactive oxygen species (ROS) production, thereby inducing endothelial cell apoptosis. Berbamine (BBM) has shown potential in neuroprotection and cardiovascular disease prevention. This study aimed to investigate the impact of ARG1 deficiency on human brain microvascular endothelial cells and the protective effects of BBM against ARG1 deficiency-induced damage. Human brain microvascular endothelial cells (HCMEC/D3) were cultured in vitro, and ARG1 knockdown or overexpression was achieved using plasmid transfection techniques. We examined the effects of ARG1 expression levels on HCMEC/D3 cell viability, migration, apoptosis, adhesion, and angiogenesis through cellular experiments. Additionally, we explored how ARG1 expression levels influenced arginine (Arg), nitric oxide (NO), and ROS levels in HCMEC/D3 cells. The results demonstrated that ARG1 deficiency inhibited HCMEC/D3 cell viability, migration, adhesion, and angiogenesis, while promoting apoptosis and elevating Arg, NO, and ROS levels in HCMEC/D3 cells. Next, the effect of different BBM concentrations on HCMEC/D3 cell viability was assessed using the CCK-8 assay, revealing that BBM at a concentration of 5 µM had no significant impact on cell viability. Subsequently, after successfully knocking down ARG1 in HCMEC/D3 cells, the cells were treated with BBM. The results showed that BBM effectively mitigated the negative effects of ARG1 deficiency on HCMEC/D3 cell viability, migration, apoptosis, adhesion, and angiogenesis, while also reducing Arg, NO, inducible nitric oxide synthase (iNOS), and ROS levels in HCMEC/D3 cells. In conclusion, this study suggests that ARG1 deficiency may damage HCMEC/D3 cells by increasing Arg levels, leading to elevated NO and ROS levels. BBM may provide protection to ARG1-deficient HCMEC/D3 cells by reducing Arg, NO, iNOS, and ROS levels. These findings deepen our understanding of the pathogenesis of CSVD and provide a theoretical basis for the clinical application of BBM.

Extracellular Vesicles From Bone Marrow-Derived Macrophages Enriched in ARG1 Enhance Microglial Phagocytosis and Haematoma Clearance Following Intracerebral Haemorrhage

Microglial phagocytosis of haematomas is crucial for neural functional recovery following intracerebral haemorrhage (ICH), a process regulated by various factors from within and outside the central nervous system (CNS). Extracellular vesicles (EVs), significant mediators of intercellular communication, have been demonstrated to play a pivotal role in the pathogenesis and progression of CNS diseases. However, the regulatory role of endogenous EVs on the phagocytic capacity of microglia post-ICH remains elusive. Utilising multi-omics analysis of brain tissue-derived EVs proteomics and single-cell RNA sequencing, this study identified that bone marrow-derived macrophages (BMDMs) potentially enhance microglial phagocytosis via EVs following ICH. By blocking BMDMs and reducing ARG1 in BMDM-derived EVs, we demonstrated that BMDMs facilitate erythrophagocytosis by delivering ARG1 to microglia via EVs post-ICH. EVs-carried ARG1 was found to augment phagocytosis by promoting RAC1-dependent cytoskeletal remodelling in microglia. Collectively, this research uncovers an intercellular communication pathway from BMDMs to microglia mediated by EVs post-ICH. This provides a novel paradigm for EV-mediated intercellular communication mechanisms and suggests a promising therapeutic potential for BMDM-derived EVs in the treatment of ICH.

Disrupting Notch signaling related HES1 in myeloid cells reinvigorates antitumor T cell responses

BACKGROUND

Tumor-associated macrophages (TAMs) are immunosuppressive cells within the tumor microenvironment (TME) that hinder anti-tumor immunity. Notch signaling is a pathway crucial for TAM differentiation and function. Here, we investigate the role of HES1, a downstream target of Notch signaling, in TAM-mediated immunosuppression and explore its potential as a target for cancer immunotherapy.

METHODS

In this work, we constructed conditional Hes1 knockout mice to selectively delete Hes1 in TAMs. We further analyzed the TME composition, T cell infiltration and activation, and anti-tumor effects in these mice, both alone and in combination with PD-1 checkpoint blockade.

RESULTS

Our study showed that expression levels of Notch target Hes1 were increase in TAMs and mice with conditional knockout of Hes1 gene in TAMs exhibited decreased tumor growth, with increased infiltration and activation of cytotoxic T cells in tumors. Expression of tumor promoting factors was critically altered in Hes1-conditional KO TAMs, leading to the improved tumor microenvironment. Notably, arginase-1 expression was decreased in Hes1-conditional KO mice. Arg1 is known to deplete arginine and deactivate T cells in the TME. Administration of anti-PD-1 monoclonal antibody inhibited tumor growth to a greater extent in Hes1-conditional KO mice than in WT mice.

CONCLUSIONS

We identified a pivotal role for the Notch signaling pathway in shaping TAM function, suggesting that T-cell dysfunction in the TME is caused when the Notch target, HES1, in TAMs is upregulated by tumor-associated factors (TAFs), which, in turn, increases the expression of arginase-1. Targeting HES1 in TAMs appears to be a promising strategy for cancer immunotherapy.

Efferocytosis: A new therapeutic target for stroke

ABSTRACT

Efferocytosis refers to the process that phagocytes recognize and remove the apoptotic cells, which is essential for maintaining tissue homeostasis both in physiological and pathological conditions. Numerous studies have demonstrated that efferocytosis can prevent secondary necrosis and proinflammatory factor release, leading to the resolution of inflammation and tissue immunological tolerance in numerous diseases such as stroke. Stroke is a leading cause of death and morbidity for adults worldwide. Persistent inflammation triggered by the dead cells or cell debris is a major contributor to post-stroke brain damage. Effective efferocytosis might be an efficient strategy to minimize inflammation and restore brain homeostasis for neuronal regeneration and function recovery. In this review, we will discuss the phagocytes in the brain, the molecular mechanisms underlying efferocytosis, the role of efferocytosis in inflammation resolution, and the potential therapeutic applications targeting efferocytosis in stroke.

Integrative multi-omics approach using random forest and artificial neural network models for early diagnosis and immune infiltration characterization in ischemic stroke

Background

Ischemic stroke (IS) is a significant global health issue, causing high rates of morbidity, mortality, and disability. Since conventional Diagnosis methods for IS have several shortcomings. It is critical to create new Diagnosis models in order to enhance existing Diagnosis approaches.

Methods

We utilized gene expression data from the Gene Expression Omnibus (GEO) databases GSE16561 and GSE22255 to identify differentially expressed genes (DEGs) associated with IS. DEGs analysis using the Limma package, as well as GO and KEGG enrichment analyses, were performed. Furthermore, PPI networks were constructed using DEGs from the String database, and Random Forest models were utilized to screen key DEGs. Additionally, an artificial neural network model was developed for IS classification. Use the GSE58294 dataset to evaluate the effectiveness of the scoring model on healthy controls and ischemic stroke samples. The effectiveness of the scoring model was evaluated through AUC analysis, and CIBERSORT analysis was conducted to estimate the immune landscape and explore the correlation between gene expression and immune cell infiltration.

Results

A total of 26 significant DEGs associated with IS were identified. Metascape analysis revealed enriched biological processes and pathways related to IS. 10 key DEGs (ARG1, DUSP1, F13A1, NFIL3, CCR7, ADM, PTGS2, ID3, FAIM3, HLA-DQB1) were selected using Random Forest and artificial neural network models. The area under the ROC curve (AUC) for the IS classification model was found to be near 1, indicating its high accuracy. Additionally, the analysis of the immune landscape demonstrated elevated immune-related networks in IS patients compared to healthy controls.

Conclusion

The study uncovers the involvement of specific genes and immune cells in the pathogenesis of IS, suggesting their importance in understanding and potentially targeting the disease.

Identifying signature genes and their associations with immune cell infiltration in spinal cord injury

Background

Early detection of spinal cord injury (SCI) is conducive to improving patient outcomes. In addition, many studies have revealed the role of immune cells in the progression or treatment of SCI. The objective of this study was to identify the early signature genes and clarify how they are related to immune cell infiltration in SCI.

Methods

We analysed and identified early signature genes associated with SCI via bioinformatics analysis of the GSE151371 dataset from the GEO database. These genes were subsequently verified in the GSE33886 dataset and qRT-PCR. Finally, the CIBERSORT algorithm was used to examine the immune cell infiltration in SCI and its relationship with signature genes.

Results

Seven SCI-related signature genes, including ARG1, RETN, BPI, GGH, CCNB1, HIST1H2AC, and HIST1H2BJ, were identified, and their expression was verified via an external validation cohort and qRT-PCR. Moreover, the ROC curves revealed the diagnostic value of these genes. In addition, on the basis of immune cell infiltration analysis, plasma cells, M0 macrophages, activated CD4+ memory T cells, γδ T cells, naive CD4+ T cells, and resting CD4+ memory T cells may participate in the progression of SCI.

Conclusion

This study identified seven early signature genes of SCI that may serve as biomarkers for the early diagnosis of SCI and contribute to our understanding of immune changes during the pathology of SCI.

Deep Proteome Coverage of Microglia Using a Streamlined Data-Independent Acquisition-Based Proteomic Workflow: Method Consideration for a Phenotypically Diverse Cell Type

As the primary innate immune cells of the brain, microglia play a key role in various homeostatic and disease-related processes. To carry out their numerous functions, microglia adopt a wide range of phenotypic states. The proteomic landscape represents a more accurate molecular representation of these phenotypes; however, microglia present unique challenges for proteomic analysis. This study implemented a streamlined liquid- and gas-phase fractionation method with data-dependent acquisition (DDA) and parallel accumulation-serial fragmentation (PASEF) analysis on a TIMS-TOF instrument to compile a comprehensive protein library obtained from adult-derived, immortalized mouse microglia with low starting material (10 µg). The empirical library consisted of 9140 microglial proteins and was utilized to identify an average of 7264 proteins/run from single-shot, data-independent acquisition (DIA)-based analysis microglial cell lysate digest (200 ng). Additionally, a predicted library facilitated the identification of 7519 average proteins/run from the same DIA data, revealing complementary coverage compared with the empirical library and collectively increasing coverage to approximately 8000 proteins. Importantly, several microglia-relevant pathways were uniquely identified with the empirical library approach. Overall, we report a simplified, reproducible approach to address the proteome complexity of microglia using low sample input and show the importance of library optimization for this phenotypically diverse cell type.

Efferocytosis: the resolution of inflammation in cardiovascular and cerebrovascular disease

Cardiovascular and cerebrovascular diseases have surpassed cancer as significant global health challenges, which mainly include atherosclerosis, myocardial infarction, hemorrhagic stroke and ischemia stroke. The inflammatory response immediately following these diseases profoundly impacts patient prognosis and recovery. Efficient resolution of inflammation is crucial not only for halting the inflammatory process but also for restoring tissue homeostasis. Efferocytosis, the phagocytic clearance of dying cells by phagocytes, especially microglia and macrophages, plays a critical role in this resolution process. Upon tissue injury, phagocytes are recruited to the site of damage where they engulf and clear dying cells through efferocytosis. Efferocytosis suppresses the secretion of pro-inflammatory cytokines, stimulates the production of anti-inflammatory cytokines, modulates the phenotype of microglia and macrophages, accelerates the resolution of inflammation, and promotes tissue repair. It involves three main stages: recognition, engulfment, and degradation of dying cells. Optimal removal of apoptotic cargo by phagocytes requires finely tuned machinery and associated modifications. Key molecules in efferocytosis, such as 'Find-me signals', 'Eat-me signals', and 'Don't eat-me signals', have been shown to enhance efferocytosis following cardiovascular and cerebrovascular diseases. Moreover, various additional molecules, pathways, and mitochondrial metabolic processes have been identified to enhance prognosis and outcomes via efferocytosis in diverse experimental models. Impaired efferocytosis can lead to inflammation-associated pathologies and prolonged recovery periods. Therefore, this review consolidates current understanding of efferocytosis mechanisms and its application in cardiovascular and cerebrovascular diseases, proposing future research directions.

Research on the innate immune response in transgenic mice following ischemic stroke

The high incidence, death, disability, and recurrence of ischemic stroke (CIS) place a significant cost on families and society. According to recent research on the condition, immune-related damage is a major contributor to the development and occurrence of CIS. Innate immunity and adaptive immunity are the two primary categories of the immune system in the body. The body's first line of defense is innate immunity, and immune cells play a role in every stage of the immune system. At the same time, protein molecules play a vital function in regulating and differentiating immune cells. It can be said that protein molecules are the foundation of immune regulation. Model mice are necessary for us to examine fixed compounds in our studies. Conditional deletion and overexpression mouse models are the two primary categories of model mice. Numerous model mice have been documented in CIS research. The study of innate immune responses following ischemic stroke will benefit more from the use of these transgenic mice that target innate immunity. This paper analyzes the literature on transgenic mice related to innate immune responses following ischemic stroke because of the significance of these responses. It is anticipated to produce novel medications, improve clinical treatment guidance, and undergo a metamorphosis and application in the clinic in the future.

M1 Microglia-Derived Exosomes Promote A1 Astrocyte Activation and Aggravate Ischemic Injury via circSTRN3/miR-331-5p/MAVS/NF-κB Pathway

Background

After ischemic stroke (IS), microglia and astrocytes undergo polarization, transforming into a pro-inflammatory phenotype (M1 or A1). According to previous studies, exosomes might play an important role in the interplay between M1 microglia and A1 astrocytes after IS.

Methods

We used the microglial oxygen-glucose deprivation/reperfusion (OGD/R) model and ultracentrifugation to extract M1 microglial exosomes (M1-exos). Subsequently, we identified circSTRN3 enriched in exosomes through RNA sequencing and detected the role of circSTRN3 in astrocyte activation based on bioinformatics analysis, immunofluorescence, Western blotting, and polymerase chain reaction analysis. We validated these findings in the middle cerebral artery occlusion/reperfusion (MCAO/R) model of adult male C57BL/6J mice. Finally, we confirmed the correlation among circSTRN3, miR-331-5p, and stroke severity score in exosomes isolated from peripheral blood of IS patients.

Results

Our findings revealed that M1-exos promoted A1 astrocyte activation. CircSTRN3 was abundant in M1-exos, which could sponge miR-331-5p to affect mitochondrial antiviral signaling protein (MAVS), activate NF-κB pathway, and participate in A1 astrocyte activation. In addition, overexpressed circSTRN3 augmented the infarct size and neurological dysfunction in MCAO/R models, while miR-331-5p mimics reversed the effect. Furthermore, circSTRN3 in IS patients was positively correlated with stroke severity score (R 2 = 0.83, P < 0.001), while miR-331-5p demonstrated a negative correlation with the same score (R 2 = 0.81, P < 0.001).

Conclusion

Taken together, our research indicated that circSTRN3 from M1-exos could promote A1 astrocyte activation and exacerbate ischemic brain injury via miR331-5p/MAVS/NF-κB axis.

Efferocytosis in atherosclerosis

Cardiovascular disease is the leading cause of death worldwide, and it commonly results from atherosclerotic plaque progression. One of the increasingly recognized drivers of atherosclerosis is dysfunctional efferocytosis, a homeostatic mechanism responsible for the clearance of dead cells and the resolution of inflammation. In atherosclerosis, the capacity of phagocytes to participate in efferocytosis is hampered, leading to the accumulation of apoptotic and necrotic tissue within the plaque, which results in enlargement of the necrotic core, increased luminal stenosis and plaque inflammation, and predisposition to plaque rupture or erosion. In this Review, we describe the different forms of programmed cell death that can occur in the atherosclerotic plaque and highlight the efferocytic machinery that is normally implicated in cardiovascular physiology. We then discuss the mechanisms by which efferocytosis fails in atherosclerosis and other cardiovascular and cardiometabolic diseases, including myocardial infarction and diabetes mellitus, and discuss therapeutic approaches that might reverse this pathological process.

Potential association between COVID-19 and neurological disorders: analysis of common genes and therapeutics

As the COVID-19 pandemic persists, the increasing evidences suggest that the patients with COVID-19 may face the risks of the neurological complications and sequelae. To address this issue, we conducted a comprehensive study aimed at exploring the relationship between COVID-19 and various neurological disorders, with a particular focus on the shared dysregulated genes and the potential therapeutic targets. We selected six neurological disorders for investigation, including Alzheimer's disease, epilepsy, stroke, Parkinson's disease, and the sleep disorders. Through the bioinformatics analysis of the association between these disorders and COVID-19, we aimed to uncover the common molecular mechanisms and the potential treatment pathways. In this study, we utilized the publicly available RNA-Seq and microarray datasets, and employed tools such as Limma and DESeq2 for the differential gene analysis. Through the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis, we explored the common biological features and pathways. Additionally, we focused on analyzing the regulatory roles of miRNA and transcription factors on the shared differentially expressed genes, and predicted the potential drugs interacting with these genes. These analyses contribute to a better understanding of the relationship between COVID-19 and the neurological disorders, and provide a theoretical basis for the future treatment strategies. Through this research, we aim to offer the deeper insights to the scientific community and present the new perspectives for the clinical practice in addressing the challenges of the neurological complications and sequelae faced by the COVID-19 patients.

Mechanism of Efferocytosis in Determining Ischaemic Stroke Resolution-Diving into Microglia/Macrophage Functions and Therapeutic Modality

After ischaemic cerebral vascular injury, efferocytosis-a process known as the efficient clearance of apoptotic cells (ACs) by various phagocytes in both physiological and pathological states-is crucial for maintaining central nervous system (CNS) homeostasis and regaining prognosis. The mechanisms of efferocytosis in ischaemic stroke and its influence on preventing inflammation progression from secondary injury were still not fully understood, despite the fact that the fundamental process of efferocytosis has been described in a series of phases, including AC recognition, phagocyte engulfment, and subsequent degradation. The genetic reprogramming of macrophages and brain-resident microglia after an ischaemic stroke has been equated by some researchers to that of the peripheral blood and brain. Based on previous studies, some molecules, such as signal transducer and activator of transcription 6 (STAT6), peroxisome proliferator-activated receptor γ (PPARG), CD300A, and sigma non-opioid intracellular receptor 1 (SIGMAR1), were discovered to be largely associated with aspects of apoptotic cell elimination and accompanying neuroinflammation, such as inflammatory cytokine release, phenotype transformation, and suppressing of antigen presentation. Exacerbated stroke outcomes are brought on by defective efferocytosis and improper modulation of pertinent signalling pathways in blood-borne macrophages and brain microglia, which also results in subsequent tissue inflammatory damage. This review focuses on recent researches which contain a number of recently discovered mechanisms, such as studies on the relationship between benign efferocytosis and the regulation of inflammation in ischaemic stroke, the roles of some risk factors in disease progression, and current immune approaches that aim to promote efferocytosis to treat some autoimmune diseases. Understanding these pathways provides insight into novel pathophysiological processes and fresh characteristics, which can be used to build cerebral ischaemia targeting techniques.

Electroacupuncture reduces inflammatory damage following cerebral ischemia-reperfusion by enhancing ABCA1-mediated efferocytosis in M2 microglia

Ischemic stroke (IS) is a severe cerebrovascular disease with high disability and mortality rates, where the inflammatory response is crucial to its progression and prognosis. Efferocytosis, the prompt removal of dead cells, can reduce excessive inflammation after IS injury. While electroacupuncture (EA) has been shown to decrease inflammation post-ischemia/reperfusion (I/R), its link to efferocytosis is unclear. Our research identified ATP-binding cassette transporter A1 (Abca1) as a key regulator of the engulfment process of efferocytosis after IS by analyzing public datasets and validating findings in a mouse model, revealing its close ties to IS progression. We demonstrated that EA can reduce neuronal cell death and excessive inflammation caused by I/R. Furthermore, EA treatment increased Abca1 expression, prevented microglia activation, promoted M2 microglia polarization, and enhanced their ability to phagocytose injured neurons in I/R mice. This suggests that EA's modulation of efferocytosis could be a potential mechanism for reducing cerebral I/R injury, making regulators of efferocytosis steps a promising therapeutic target for EA benefits.

Intestinal Akkermansia muciniphila is Beneficial to Functional Recovery Following Ischemic Stroke

Recent studies have demonstrated the interaction between gut microbiota and brain on ischemic stroke, but the roles of gut microbiota in the pathophysiology of ischemic stroke remain largely unclear. In this study, we detected a significant increase of intestinal Akkermansia muciniphila (AKK) following ischemic stroke by a rose bengal photothrombosis model. To investigate the function and mechanism of AKK on ischemic stroke, we performed the AKK administration prior to stroke surgery. The results showed that mice treated with AKK gained significantly higher body weight and behaved better than those in PBS group at 3 days after ischemic stroke. Consistently, AKK administration remarkably decreased the infarct volumes as well as the density of degenerating neurons and apoptotic cells after ischemic stroke. Notably, AKK is a potential therapeutic target in immune-related disorders connected to the microbiota, and inflammation is crucially involved in the pathophysiological process of ischemic stroke. For the determination of underlying mechanisms of this protective effect, we investigated whether there are associations between AKK and neuroinflammation following ischemic stroke. The results suggested that AKK administration significantly reduced the activation of astrocytes and microglia but up-regulated multiple anti-inflammatory factors following ischemic stroke. Therefore, our study highlighted the beneficial roles of intestinal AKK on ischemic stroke and provided a new perspective for the treatment of ischemic stroke.

Resolution of inflammation, an active process to restore the immune microenvironment balance: A novel drug target for treating arterial hypertension

The resolution of inflammation, the other side of the inflammatory response, is defined as an active and highly coordinated process that promotes the restoration of immune microenvironment balance and tissue repair. Inflammation resolution involves several key processes, including dampening proinflammatory signaling, specialized proresolving lipid mediator (SPM) production, nonlipid proresolving mediator production, efferocytosis and regulatory T-cell (Treg) induction. In recent years, increasing attention has been given to the effects of inflammation resolution on hypertension. Furthermore, our previous studies reported the antihypertensive effects of SPMs. Therefore, in this review, we aim to summarize and discuss the detailed association between arterial hypertension and inflammation resolution. Additional, the association between gut microbe-mediated immune and hypertension is discussed. This findings suggested that accelerating the resolution of inflammation can have beneficial effects on hypertension and its related organ damage. Exploring novel drug targets by focusing on various pathways involved in accelerating inflammation resolution will contribute to the treatment and control of hypertensive diseases in the future.

S100A9 deletion in microglia/macrophages ameliorates brain injury through the STAT6/PPARγ pathway in ischemic stroke

BACKGROUND

Microglia and infiltrated macrophages (M/M) are integral components of the innate immune system that play a critical role in facilitating brain repair after ischemic stroke (IS) by clearing cell debris. Novel therapeutic strategies for IS therapy involve modulating M/M phenotype shifting. This study aims to elucidate the pivotal role of S100A9 in M/M and its downstream STAT6/PPARγ signaling pathway in neuroinflammation and phagocytosis after IS.

METHODS

In the clinical study, we initially detected the expression pattern of S100A9 in monocytes from patients with acute IS and investigated its association with the long-term prognosis. In the in vivo study, we generated the S100A9 conditional knockout (CKO) mice and compared the stroke outcomes with the control group. We further tested the S100A9-specific inhibitor paqunimod (PQD), for its pharmaceutical effects on stroke outcomes. Transcriptomics and in vitro studies were adopted to explore the mechanism of S100A9 in modulating the M/M phenotype, which involves the regulation of the STAT6/PPARγ signaling pathway.

RESULTS

S100A9 was predominantly expressed in classical monocytes and was correlated with unfavorable outcomes in patients of IS. S100A9 CKO mitigated infarction volume and white matter injury, enhanced cerebral blood flow and functional recovery, and prompted anti-inflammation phenotype and efferocytosis after tMCAO. The STAT6/PPARγ pathway, an essential signaling cascade involved in immune response and inflammation, might be the downstream target mediated by S100A9 deletion, as evidenced by the STAT6 phosphorylation inhibitor AS1517499 abolishing the beneficial effect of S100A9 inhibition in tMCAO mice and cell lines. Moreover, S100A9 inhibition by PQD treatment protected against neuronal death in vitro and brain injuries in vivo.

CONCLUSION

This study provides evidence for the first time that S100A9 in classical monocytes could potentially be a biomarker for predicting IS prognosis and reveals a novel therapeutic strategy for IS. By demonstrating that S100A9-mediated M/M polarization and phagocytosis can be reversed by S100A9 inhibition in a STAT6/PPARγ pathway-dependent manner, this study opens up new avenues for drug development in the field.

Rapamycin Alleviates Neuronal Injury and Modulates Microglial Activation After Cerebral Ischemia

Neurons and microglia are sensitive to cerebral microcirculation and their responses play a crucial part in the pathological processes, while they are also the main target cells of many drugs used to treat brain diseases. Rapamycin exhibits beneficial effects in many diseases; however, whether it can affect neuronal injury or alter the microglial activation after global cerebral ischemia remains unclear. In this study, we performed global cerebral ischemia combined with rapamycin treatment in CX3CR1GFP/+ mice and explored the effects of rapamycin on neuronal deficit and microglial activation. Our results showed that rapamycin reduced neuronal loss, neurodegeneration, and ultrastructural damage after ischemia by histological staining and transmission electron microscopy (TEM). Interestingly, rapamycin suppressed de-ramification and proliferation of microglia and reduced the density of microglia. Immunofluorescence staining indicated that rapamycin skewed microglial polarization toward an anti-inflammatory state. Furthermore, rapamycin as well suppressed the activation of astrocytes. Meanwhile, quantitative real-time polymerase chain reaction (qRT-PCR) analyses revealed a significant reduction of pro-inflammatory factors as well as an elevation of anti-inflammatory factors upon rapamycin treatment. As a result of these effects, behavioral tests showed that rapamycin significantly alleviated the brain injury after stroke. Together, our study suggested that rapamycin attenuated neuronal injury, altered microglial activation state, and provided a more beneficial immune microenvironment for the brain, which could be used as a promising therapeutic approach to treat ischemic cerebrovascular diseases.