M2 Microglia Research Articles

Ghrelin Induces Ferroptosis Resistance and M2 Polarization of Microglia to Alleviate Neuroinflammation and Cognitive Impairment in Alzheimer's Disease.

Microglial polarization and ferroptosis are important pathological features in Alzheimer's disease (AD). Ghrelin, a brain-gut hormone, has potential neuroprotective effects in AD. This study aimed to explore the potential mechanisms by which ghrelin regulates the progression of AD, as well as the crosstalk between microglial polarization and ferroptosis.Mouse BV2 microglial cells and male mice were treated with beta-amyloid (Aβ) (1-42) to simulate the AD environment. Microglia ferroptosis was measured by detecting levels of ferroptosis-related proteins (SLC7A11, GPX4, FTL1, and FTH1), metabolic markers (ROS, MDA, GSH, SOD), and observing mitochondrial morphological changes. Microglial polarization was evaluated by measuring levels of inflammatory markers and surface markers. The impact of ghrelin on Aβ1-42-exposed microglia was assessed by coupling with the ferroptosis activator Erastin. Cognitive impairment in AD mice was evaluated through behavioral tests. Tissue staining was applied to determine neuronal damage.In Aβ1-42-exposed microglia, ghrelin upregulated the protein expression of SLC7A11, GPX4, FTL1 and FTH1, reduced ROS and MDA levels, and elevated GSH and SOD levels through the BMP6/SMAD1 pathway. Ghrelin alleviated mitochondrial structural damage. Additionally, ghrelin reduced levels of pro-inflammatory factors and CD86, while increasing levels of anti-inflammatory factors and CD206. Erastin reversed the effects of ghrelin on ferroptosis and phenotypic polarization in Aβ1-42-exposed microglia. In AD mice, ghrelin ameliorated abnormal behavior, neuroinflammation, and plaque deposition. Ghrelin attenuated iNOS/IBA1-positive expression and enhanced Arg-1/IBA1-positive expression in the hippocampus. Ghrelin induces microglial M2 polarization by inhibiting microglia ferroptosis, thereby alleviating neuroinflammation. Our results indicate that ghrelin may serve as a promising potential agent for treating cognitive impairment in AD.

Genetically Programmed Single-Component Protein Hydrogel for Spinal Cord Injury Repair.

Protein self-assembly allows for the formation of diverse supramolecular materials from relatively simple building blocks. In this study, a single-component self-assembling hydrogel is developed using the recombinant protein CsgA, and its successful application for spinal cord injury repair is demonstrated. Gelation is achieved by the physical entanglement of CsgA nanofibrils, resulting in a self-supporting hydrogel at low concentrations (≥5mg mL-1). By leveraging the programmability of the CsgA gene sequence, the bioactive hydrogel is enhanced by fusing functional peptide GHK. GHK is recognized for its anti-inflammatory, antioxidant, and neurotrophic factor-stimulating properties, making it a valuable addition to the hydrogel for spinal cord injury repair applications. In vitro experiments demonstrate that the CsgA-GHK hydrogel can modulate microglial M2 polarization, promote neuronal differentiation of neural stem cells, and inhibit astrocyte differentiation. Additionally, the hydrogel shows efficacy in alleviating inflammation and promotes neuronal regeneration at the injury site, leading to significant functional recovery in a rat model with compression injury spinal cord cavity. These findings lay the groundwork for developing a modular design platform for recombinant CsgA protein hydrogels in tissue repair applications.

Molecular mechanism of METTL14-mediated m6A modification regulating microglial function post ischemic stroke

This study explores the molecular mechanism of METTL14 regulating microglial function post ischemic stroke. A murine model was established by tMCAO. The neurological function was evaluated by mNSS. The cerebral infarct size and pathological changes were observed by TTC and H&E staining. M1 and M2 microglia in brain tissues were detected by flow cytometry. BV2 cells were subjected to OGD/R to establish an in vitro model. qRT-PCR and Western blot were used for detecting METTL14, PAX6, YTHDF2, TREM2, iNOS, and Arg1 expressions. The m6A level was quantitatively analyzed, and the binding of YTHDF2 or m6A to PAX6 was analyzed by RIP. PAX6 mRNA stability was assessed after actinomycin D treatment. ChIP was utilized for determining the enrichment of PAX6 on TREM2 promoter. The binding relationship between TREM2 and PAX6 was verified by dual-luciferase reporter assay. METTL14 was highly expressed after tMCAO, and silence of METTL14 alleviated symptoms of tmcao mice and promoted microglial M2 polarization. METTL14 enhanced PAX6 mRNA m6A modification to promote YTHDF2 binding to PAX6 mRNA and its degradation. PAX6 bound to TREM2 promoter and facilitated its transcription and expression. In conclusion, METTL14-mediated m6A modification aggravates ischemic stroke by promoting microglial M1 polarization via YTHDF2/PAX6/TREM2 axis.

Development of research on mechanisms of acupuncture intervention on ischemic stroke and its relationship with microglia

Microglia, the main phagocytic cells in the brain, play a key role in inflammatory response and neuroprotection in ischemic stroke, and are potential targets for the treatment of ischemic stroke. Multiple studies have confirmed that the effect of acupuncture on ischemic stroke is closely related to its effect in regulating the activities of microglia. In the present paper, we reviewed the role of microglia in ischemic stroke and the current research status of acupuncture intervention, and prospects the future research direction. Past researches showed that microglia have a bidirectional role in the pathological process of cerebral ischemia, that is, M1 microglia can secrete pro-inflammatory cytokines, participate in the damage of the blood-brain barrier, and aggravate the damage of neurotoxicity, and M2 microglia can secrete anti-inflammatory cytokines, nerve growth factors, neurotrophic factors, improve neuroplasticity and promote vascular remodeling. Acupuncture can exert brain protective effects by regulating the activation and polarization direction of microglia, inhibiting inflammatory reactions, maintaining the integrity of the blood-brain barrier, promoting vascular remodeling, and promoting nerve regeneration. However, whether acupuncture intervention in different periods can affect the response of microglia and how it affects, and whether different acupuncture parameters have different effects on the regulation of microglia, it needs further research. In addition, more in-depth and multi-angle systematic studies on polarization of microglia, secretion factors, cell relationships, upstream and downstream regulatory factors and other aspects with microglia are definitely needed.

Temporal therapy utilizing exosomes derived from M2 macrophages demonstrates enhanced efficacy in alleviating neuropathic pain in diabetic rats.

Diabetic pain patients have increased pain at night. Exosomes can relieve neuropathic pain. This study aimed to investigate the efficacy of exosome administration at different time points in relieving diabetic neuropathic pain (DNP) in rats. M2 macrophages from bone marrow were induced in mice and exosomes were extracted. A diabetic rat model was induced using streptozotocin, with the mechanical withdrawal threshold (MWT) of the rats being measured at ≤ 80% of the basal value after 14 days, indicating successful construction of the DNP rat model. Exosomes were administered on three consecutive days at ZT0 (zeitgeber time) and ZT12. Parameters including blood glucose levels, body weight, MWT, and thermal withdrawal latency (TWL) were assessed in the rats. The lumbar spinal cord of rats was examined on days 21 and 28 to measure inflammatory factors and observe the expression of M1 and M2 microglia. Furthermore, microglia were exposed to lipopolysaccharide (LPS) and LPS + exosomes in a controlled in vitro setting to assess alterations in microglia phenotype involving the NF-kB p65 and IKBα inflammatory signaling pathways. The findings revealed that administration of exosomes during the rat resting period at ZT12 resulted in increased MWT and TWL, as well as a shift in microglia polarization towards the M2 phenotype. In vitro analysis indicated that exosomes influenced microglia polarization and suppressed the phosphorylation of NF-kB p65 and IKBα. Temporal therapy with exosomes effectively reduces pain in DNP rats by polarizing microglia and affecting NF-kB p65 and IKBα signaling pathways.

Maresin-like 1 Ameliorates Neuropathology of Alzheimer's Disease in Brains of a Transgenic Mouse Model.

(1) Background: Impeded resolution of inflammation contributes substantially to the pathogenesis of Alzheimer's disease (AD); consequently, resolving inflammation is pivotal to the amelioration of AD pathology. This can potentially be achieved by the treatment with specialized pro-resolving lipid mediators (SPMs), which should resolve neuroinflammation in brains. (2) Methods: Here, we report the histological effects of long-term treatment with an SPM, maresin-like 1 (MarL1), on AD pathogenesis in a transgenic 5xFAD mouse model. (3) Results: MarL1 treatment reduced Aβ overload, curbed the loss of neurons in brains especially cholinergic neurons associated with cleaved-caspase-3-associated apoptotic degeneration, reduced microgliosis and the pro-inflammatory M1 polarization of microglia, curbed the AD-associated decline in anti-inflammatory Iba1+Arg-1+-M2 microglia, inhibited phenotypic switching to pro-inflammatory N1 neutrophils, promoted the blood-brain barrier-associated tight-junction protein claudin-5 and decreased neutrophil leakage in 5xFAD brains, and induced the switch of neutrophils toward the inflammation-resolving N2 phenotype. (4) Conclusions: Long-term administration of MarL1 mitigates AD-related neuropathogenesis in brains by curbing neuroinflammation and neurodegeneration, based on the histological results. These findings provide preclinical leads and mechanistic insights for the development of MarL1 into an effective modality to ameliorate AD pathogenesis.

AEBP1 Silencing Protects Against Cerebral Ischemia/Reperfusion Injury by Regulating Neuron Ferroptosis and Microglia M2 Polarization Through PRKCA-PI3K-Akt Axis.

Cerebral ischemia/reperfusion injury is one of the main causes of neuronal damage. Neuron ferroptosis and microglia polarization are considered as critical processes during cerebral ischemia/reperfusion. Adipocyte enhancer-binding protein 1 (AEBP1) usually acts as a transcriptional repressor which is involved in various diseases. However, it is still remains unknown whether AEBP1 could have important roles in regulating the neuron ferroptosis and microglia polarization in cerebral ischemia/reperfusion injury. The oxygen-glucose deprivation and reperfusion (OGD/R)-treated cells and middle cerebral artery occlusion (MCAO)-treated mice were used as in vitro and in vivo models. The differentially expressed factors were analyzed according to GEO datasets. Relative mRNA and protein expression levels were detected by qRT-PCR and western blot analysis. Cell viability was measured by CCK-8 assay. ROS, GSH and iron contents were detected using specifical assay kits. CD26 and CD206 levels were measured by immunofluorescence assay. Inflammatory cytokines were detected by ELISA. The association between AEBP1 and PRKCA was assessed by luciferase reporter and ChIP analyses. The neuron damage in mice was analyzed by TTC staining and neurological deficit score. Transcription factor AEBP1 was increased in OGD/R-treated HT22 and BV2 cells. AEBP1 silencing attenuated OGD/R-induced HT22 cell ferroptosis through increasing cell viability, GSH and GPX4 levels, and decreasing ROS, iron and ACSL4 levels. AEBP1 knockdown promoted microglia M2 polarization by increasing CD206-positive cells and Arg-1 level, and reducing iNOS, TNF-α, IL-1β and IL-6 levels in BV2 cells. AEBP1 transcriptionally repressed PRKCA expression, and further regulated PI3K/Akt signaling activation. Inhibition of PRKCA or PI3K/Akt reversed the effects of AEBP1 silencing on neuron ferroptosis and microglia M2 polarization. AEBP1 downregulation attenuated neuronal damage by decreasing infarct size and deficit scores in MCAO-treated mice. AEBP1 silencing mitigated neuron ferroptosis and promoted microglia M2 polarization through increasing PRKCA and activating PI3K/Akt signaling, indicating the potentially protective action of AEBP1 knockdown in cerebral ischemia/reperfusion injury.

Quercetin Regulates the Polarization of Microglia through the NRF2/HO1 Pathway and Mitigates Alzheimer's Disease.

Alzheimer's disease (AD) is a burdening disease and is the main cause of dementia. Quercetin (Que), an antioxidant, plays potential roles in treating age-related disorders, including AD. This study aimed to validate the effects of Que on AD and explore the underlying mechanisms. Mice with no treatment, amyloid-β Aβ (1-42) treatment (for acquiring AD model), or Aβ (1-42) plus Que treatment were used. Cognitive function was determined using the open field test (OFT), objective recognition test, and Y-maze test. In brain tissues, mRNA levels of inflammation cytokines, the M1 microglia marker cluster of differentiation (CD)86, and the M2 microglia markers arginase 1 (Arg1) and CD206 were measured. Nuclear factor E2-related factor 2 (NRF2)/heme oxygenase-1 (HO1) pathway-related proteins were detected by western blot. Additionally, mechanisms were investigated using human microglia HMC3 cells treated with Aβ (1-42) and Aβ (1-42) plus Que. The NRF2/HO1 pathway in HMC3 cells was inhibited using the selective inhibitor ML385. Cell viability and death were assessed using the cell counting kit-8 (CCK-8) and lactate dehydrogenase (LDH) release levels, respectively. Cell apoptosis was measured by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL). Levels of NRF2/HO1 pathway-related proteins, inflammation cytokines, and oxidative stress-related markers, including malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione (reduced glutathione (GSH)/oxidized glutathione disulfide (GSSG)), were determined in HMC3 cells. Flow cytometry was used to determine M1 markers CD86 and CD80 and M2 markers CD206 and CD163. Cognitive ability was impaired in AD model mice, and Que treatment reversed this impairment (p < 0.05). Levels of interleukin (IL)-1β, tumor necrosis factor-alpha (TNF-α), and IL-6 were increased, while M2 markers were decreased in the AD model mouse brain. Que treatment reversed these changes (p < 0.001). The NRF2/HO1 pathway was slightly inhibited in AD mice brain, while further activated by Que (p < 0.05). Que reversed the Aβ (1-42)-impaired cell viability. Through greatly activating NRF2/HO1 pathway, Que suppressed Aβ (1-42)-induced cell death, decreased Aβ (1-42)-promoted IL-1β, TNF-α, IL-6, MDA, CD86 and CD80, increased Aβ (1-42)-suppressed SOD and GSH/GSSG, and greatly increased CD206 and CD163 (p < 0.01). Quercetin, through the activation of the NRF2/HO1 pathway, promotes M2 polarization of microglia, suppresses Aβ (1-42)-induced inflammation and oxidative stress, protects microglia from Aβ (1-42)-induced damage, improves cognitive function in mice, and demonstrates therapeutic potential for AD.

USP22 Inhibits Microglial M1 Polarization by Regulating the PU.1/NLRP3 Inflammasome Pathway

ObjectiveThis study aimed to investigate the effect of Ubiquitin-Specific Peptidase 22 (USP22) on the inflammatory response mediated by BV-2 mouse microglia and explore the role of the PU box binding protein 1 (PU.1)/NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome in the USP22-induced polarization of BV-2 cells. MethodsThe BV-2 mouse microglia line was cultured in vitro, and plasmid and siRNA transfection was performed to overexpress or knockdown USP22. Subsequently, BV-2 cells were treated with lipopolysaccharide (LPS) and interferon-gamma (IFN-γ) and interleukin (IL)-4 to induce M1 and M2 polarization, respectively. Western blot was used to detect the expression levels of USP22, PU.1, M1 polarization markers [inducible nitric oxide synthase (iNOS), and cluster of differentiation (CD) 86], M2 polarization markers [arginase 1 (Arg1), and CD206], in BV-2 cells from different treatment groups. Additionally, measurement was performed on the inflammasome NLRP3, and its activation-related proteins [NIMA-related kinase7 (NEK7), cleaved-caspase 1, apoptosis-associated speck-like protein containing a CARD (ASC)]. Enzyme-linked immunosorbent (ELISA) assay was employed to determine the levels of inflammatory cytokines tumor necrosis factor-alpha (TNF-α), IL-1 β, and IL-10 in the cells. Furthermore, immunofluorescence was utilized to analyze the levels of iNOS and Arg1-positive BV-2 cells in different treatment groups. Moreover, the ubiquitination level of PU.1 was detected using immunoprecipitation. ResultsThe protein expression level of USP22 was significantly down-regulated in BV-2 cells treated with M1 polarization. Overexpression of USP22 remarkably reduced the protein levels of iNOS and CD86, but markedly increased the protein levels of Arg1 and CD206 in cells. Besides, there was a notable reduction in the levels of TNF-α and IL-1 β in the cell culture medium, while a remarkable increase was observed in the level of IL-10. Additionally, the level of iNOS-positive cells was significantly decreased, while the level of Arg1-positive cells was considerably increased. However, up-regulation of PU.1 expression could reverse the above results and promoted the expression of NLRP3 and its activation-related proteins. Notably, overexpression of USP22 significantly down-regulated the protein expression and ubiquitination level of PU.1. ConclusionUSP22 inhibits the M1 polarization of BV-2 mouse microglia. The PU.1/NLRP3 inflammasome pathway may be a critical regulatory pathway of USP22 in BV-2 cell polarization.

P2Y6R Inhibition Induces Microglial M2 Polarization by Promoting PINK1/Parkin-Dependent Mitophagy After Spinal Cord Injury.

Secondary injury presents a significant hurdle to neural regeneration following spinal cord injury (SCI), primarily driven by inflammation in which microglial cells play a crucial role. Despite the growing interest in mitophagy, studies on its occurrence post-spinal cord injury, particularly within microglial cells, are scarce. While P2Y6R has been implicated in inflammation regulation in various neurological conditions, its specific role in SCI remains uncertain. Our study revealed an upregulation of P2Y6R expression following SCI notably in microglial cells. Treatment with the P2Y6R-specific inhibitor, MRS2578, in mice facilitated M2 polarization of microglial cells and alleviated secondary damage, ultimately enhancing neural regeneration and functional recovery. In an in vitro BV2 inflammation model, our findings indicate that P2Y6R inhibition induced M2 polarization of BV2 cells and reduced neuroinflammation through PINK/Parkin-dependent mitophagy activation. In summary, our results underscore the potential of P2Y6R inhibition in promoting mitophagy-induced M2 polarization of microglial cells, thereby ameliorating secondary injury following spinal cord injury.

Quercetin alleviates neonatal hypoxic-ischaemic brain injury by rebalancing microglial M1/M2 polarization through silent information regulator 1/ high mobility group box-1 signalling.

Neonatal hypoxic-ischaemic encephalopathy (HIE) remains one of the major causes of neonatal death and long-term neurological disability. Due to its complex pathogenesis, there are still many challenges in its treatment. In our previous studies, we found that quercetin can alleviate neurological dysfunction after hypoxic-ischaemic brain injury (HIBI) in neonatal mice. As demonstrated through in vitro experiments, quercetin can inhibit the activation of the TLR4/MyD88/NF-κB signalling pathway and the inflammatory response in the microglial cell line BV2 after oxygen-glucose deprivation. However, the in-depth mechanism still needs to be further elucidated. In the present study, 7day-old neonatal ICR mice or BV2 cells were treated with quercetin with or without the SIRT1 inhibitor EX527 via neurobehavioural, histopathological and molecular methods. In vivo experiments have shown that quercetin can significantly improve the performance of HI mice in behavioural tests, such as the Morris water maze, rotarod test and pole climbing test, and reduce HI insult-induced structural brain damage, cell apoptosis and hippocampal neuron loss. Quercetin also inhibited the immunofluorescence intensity of the microglial M1 marker CD16 + 32 and significantly downregulated the expression of the M1-related proteins iNOS, IL-1β and TNF-α. Moreover, quercetin increased the immunofluorescence intensity of the microglial M2 marker CD206 and significantly increased the expression of the M2-related proteins Arg-1 and IL-10. In addition, quercetin limits the nucleocytoplasmic translocation and release of microglial HMGB1 and further suppresses the activation of the downstream TLR4/MyD88/NF-κB signalling pathway. The above effects of quercetin are partially weakened by pretreatment with EX527. Similar results were found in in vitro experiments, and the mechanism further revealed that the rebalancing effect of quercetin on microglial polarization is achieved through the SIRT1-mediated reduction in HMGB1 acetylation levels. This study provides new and complementary insights into the neuroprotective effects of quercetin and a new direction for the treatment of neonatal HIE.

GIV/Girdin Modulation of Microglial Activation in Ischemic Stroke: Impact of FTO-Mediated m6A Modification.

Ischemic stroke (IS) is one of the most common causes of death in the world. The lack of effective pharmacological treatments for IS was primarily due to a lack of understanding of its pathogenesis. Gα-Interacting vesicle-associated protein (GIV/Girdin) is a multi-modular signal transducer and guanine nucleotide exchange factor that controls important signaling downstream of multiple receptors. The purpose of this study was to investigate the role of GIV in IS. In the present study, we found that GIV is highly expressed in the central nervous system (CNS). GIV protein level was decreased, while GIV transcript level was increased in the middle cerebral artery occlusion reperfusion (MCAO/R) mice model. Additionally, GIV was insensitive lipopolysaccharide (LPS) exposure. Interestingly, we found that GIV overexpression dramatically restrained microglial activation, inflammatory response, and M1 polarization in BV-2 microglia induced by oxygen-glucose deprivation and reoxygenation (OGD/R). On the contrary, GIV knockdown had the opposite impact. Mechanistically, we found that GIV activated the Wnt/β-catenin signaling pathway by interacting with DVL2 (disheveled segment polarity protein 2). Notably, m6A demethylase fat mass and obesity-associated protein (FTO) decreased the N6-methyladenosine (m6A) modification-mediated increase of GIV expression and attenuated the inflammatory response in BV-2 stimulated by OGD/R. Taken together, our results demonstrate that GIV inhibited the inflammatory response via activating the Wnt/β-catenin signaling pathway which expression regulated in an FTO-mediated m6A modification in IS. These results broaden our understanding of the role of the FTO-GIV axis in IS development.

Astragalus polysaccharide treatment relieves cerebral ischemia‒reperfusion injury by promoting M2 polarization of microglia by enhancing O-GlcNAcylation.

Cerebral ischemia‒reperfusion (I/R) injury seriously threatens the lives of patients. Astragalus polysaccharide (APS) is the main active ingredient of Astragalus membranaceus and has a wide range of pharmacological activities. Here, we aimed to explore the impacts of APS on cerebral I/R injury and its specific mechanisms. We established a cerebral I/R injury model using middle cerebral artery occlusion (MCAO)-treated rats and oxygen glucose deprivation/reoxygenation (OGD/R)-treated BV2 cells. The interleukin 1β (IL-1β), interleukin 6 (IL-6) and interleukin (IL-10) levels were determined using corresponding ELISA kits and RT‒qPCR. The levels of M1 microglial markers (INOS and CD16) and M2 microglial markers (Arg-1 and CD206) were measured by RT‒qPCR. The O-linked N-acetylglucosamine modification (O-GlcNAcylation), O-GlcNAc transfer (OGT) and O-GlcNAc glycosidase (OGA) protein levels were measured by Western blot.Our results showed that APS treatment decreased IL-1β (179.72 ± 9.08 vs. 81.33 ± 6.30) and IL-6 (445.56 ± 33.09 vs. 234.75 ± 27.62) levels and increased IL-10 (41.95 ± 4.18 vs. 86.40 ± 7.16) levels in OGD/R-treated BV2 cells (p < 0.001). In addition, APS promoted the M2 polarization of OGD/R-treated BV2 cells, manifested by an increase in Arg-1 (0.43 ± 0.04 vs. 0.76 ± 0.03) and CD206 (0.36 ± 0.03 vs. 0.65 ± 0.06) and a decrease in INOS (2.84 ± 0.39 vs. 1.56 ± 0.19) and CD16 (4.04 ± 0.36 vs. 1.88 ± 0.09) in OGD/R-treated BV2 cells (p < 0.001). Additionally, APS treatment increased the O-GlcNAcylation and OGT levels in OGD/R-treated BV2 cells, while OGT knockdown reversed the effect of APS in OGD/R-treated BV2 cells and MCAO-treated rats (p < 0.05).Our study demonstrated that APS alleviated cerebral I/R injury by promoting the M2 polarization of microglia by enhancing OGT-mediated O-GlcNAcylation.

Procaine Regulates the STAT3/CCL5 Axis and Inhibits Microglia M1 Polarization to Alleviate Complete Freund's Adjuvant Rats Pain Behavior.

Neuropathic pain (NP) caused by sciatic nerve injury can significantly impact the quality of life of patients. The M1 phenotype of microglia has been reported to promote the progression of NP. Procaine is a lipid-soluble local anesthetic drug that exerts narcotic analgesic effects. Nevertheless, the detailed effect of procaine in NP is not clear. In order to explore the role of procaine in the polarization of NP microglia, HAPI cells were exposed to LPS to polarize into M1 type. In addition, the number of the M1 phenotype of HAPI cells was assessed using flow cytometry. The binding site between CCL5 and STAT3 was explored using the dual luciferase assay. Furthermore, in vivo experiments were applied for testing the impact of procaine on NP. LPS significantly inhibited HAPI cell viability, which was reversed by procaine. Consistently, procaine alleviated LPS-induced upregulation of inflammatory factors. Additionally, it significantly inhibited HAPI cell M1 polarization induced by LPS. Meanwhile, overexpression of STAT3 was able to promote HAPI cells M1 polarization through binding with the CCL5 promoter region and activating the PI3K/Akt signaling. Procaine could alleviate the painful behavior of complete Freund's adjuvant (CFA) rats by modulating the STAT3/CCL5 axis and inhibiting microglia M1 polarization. In conclusion, procaine alleviated the painful behavior of CFA rats via regulating the STAT3/CCL5 axis and inhibiting microglia M1 polarization. Hence, the research might provide a novel agent for NP treatment.

(+)-Borneol inhibits neuroinflammation and M1 phenotype polarization of microglia in epileptogenesis through the TLR4-NFκB signaling pathway.

To investigate the effect of (+)-borneol on neuroinflammation and microglia phenotype polarization in epileptogenesis and its possible mechanism. Based on mouse models of status epilepticus (SE) induced by pilocarpine, and treated with 15 mg/kg (+)-borneol, western-blot was used to detect the expressions of NeuN, Iba-1, TLR4, p65 and p-p65 in the hippocampus. Immunofluorescence was used to detect the expression of apoptosis-related proteins Bax and Bcl-2. To explore the effect of (+)-borneol on microglia in vitro, we used the kainic acid-induced microglia model and the concentration of (+)-borneol was 25 μM according to CCK-8 results. The levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-10 (IL-10) in the supernatant of each group was detected by ELISA. The nitric oxide (NO) content in the supernatant was detected by Griess method. The expressions of Iba-1 and TLR4-NFκB signaling pathway-related proteins (TLR4, p65, p-p65) were detected by Western-Blot. Immunofluorescence was used to detect microglia's M1 and M2 phenotype polarization and the expression of Iba-1 and TLR4. (+)-borneol reduced hippocampal neuronal injury, apoptosis, and microglia activation by inhibiting the TLR-NFκB signaling pathway in SE mice. TLR4 agonist LPS partially reversed the neuroprotective effect of (+)-borneol. In the KA-induced microglia model, (+)-borneol inhibited microglia activation, M1 phenotype polarization, and secretion of pro-inflammatory cytokines through the TLR4-NFκB signaling pathway. LPS treatment inhibited the therapeutic effects of (+)-borneol. (+)-borneol inhibits microglial neuroinflammation and M1 phenotype polarization through TLR4-NFκB signaling pathway and reduces neuronal damage and apoptosis in SE mice. Therefore, (+)-borneol may be a potential drug for epilepsy modification therapy.

KDM4A facilitates neuropathic pain and microglial M1 polarization by regulating BDNF in a rat model of brachial plexus avulsion

BackgroundMany patients with brachial plexus avulsion (BPA) suffer from neuropathic pain, but the mechanism remains elusive. Modifications of histones, the proteins responsible for organizing DNA, may play an important role...

Exosomes from polarized Microglia: Proteomic insights into potential mechanisms affecting intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a devastating form of stroke associated with significant morbidity and mortality. Microglia are intracranial innate immune cell that play critical roles in Intracerebral hemorrhage through direct or indirect means. Vesicle transport is a fundamental mechanism of intercellular communication. Recent studies have identified microglia in specific polarized states correlate with pathogenesis, material and signal transmission in ICH through derived extracellular vesicles. Diverse polarization states trigger distinct functions, however, the exosome proteomes across these states remain poorly characterized. Here, we hypothesized that microglia exosomal profiles vary with polarization states, impacting their functional repertoire and influencing outcomes in cerebral hemorrhage. In vitro model of cerebral hemorrhage, administration of 20 μg/ml LPS-induced M1 microglia derived exosomes (M1-Exo) with HT22 enhanced hemin-induced neuronal death, while IL-4-induced M2 microglia derived exosomes (M2-Exo) significantly reduced hemin-induced cell apoptosis and inflammation. Then we identified novel state-specific proteomic profiles of microglia-derived exosomes under these polarization conditions through label-free quantitative mass spectrometry (LFQ-MS). Analysis of protein content identified several exosomal signature proteins and hundreds of differentially expressed proteins across polarization states. Specifically, proteins including UMOD, NLRP3, ACOD1, IL1RN, heme oxygenase 1 (HMOX1), CCL4, and TNFRSF1B in M1-Exo were enriched in inflammatory pathways, while those in M2-Exo exhibited enrichment in autophagy, ubiquitination, and mitochondrial respiration. The analysis of those diverse exosomal proteins suggested unique proteomic profiles and possible intracellular signal transmission and regulation mechanisms. Together, these findings offer new insights and resources for studying microglia-derived exosome and pave the way for the development of novel therapeutic strategies targeting microglial exosome-mediated pathways.

Ultrasound Stimulation Modulates Microglia M1/M2 Polarization and Affects Hippocampal Proteomic Changes in a Mouse Model of Alzheimer's Disease.

The effectiveness of ultrasound stimulation in treating Alzheimer's disease (AD) has been reported in previous studies, but the underlying mechanisms remain unclear. This study investigated the effects of ultrasound stimulation on the proportion and function of microglia of different phenotypes, as well as on the levels of inflammatory factors. Additionally, it revealed the alterations in proteomic molecules in the mouse hippocampus following ultrasound stimulation treatment, aiming to uncover potential new molecular mechanisms. Ultrasound stimulation was used to stimulate the hippocampus for 30 min per day for 5 days in the ultrasound stimulation-treated group. Amyloid plaque deposition was measured using immunofluorescence staining. M1 and M2 type microglia were labeled using immunofluorescent double staining, and the ratio was calculated. The levels of Aβ42, IL-10, and TNF-α were determined using ELISA kits. The quantitative proteomics method was employed to explore molecular changes in hippocampal proteins. Ultrasound stimulation treatment reduced the average fluorescence intensity of amyloid plaques and the concentration of Aβ42. Compared to the AD group, ultrasound stimulation resulted in a 14% reduction in the proportion of M1 microglia and a 12% increase in the proportion of M2 microglia. The concentration of the anti-inflammatory factor IL-10 was significantly increased in the ultrasound stimulation-treated group. Proteomics analysis revealed 753 differentially expressed proteins between the ultrasound stimulation-treated and AD groups, with most being enriched in the oxidative phosphorylation pathway of mitochondria. Additionally, the activity of cytochrome c oxidase, involved in oxidative phosphorylation, was increased after ultrasound stimulation treatment. Ultrasound stimulation affects microglial polarization, reduces amyloid plaque load, and enhances levels of anti-inflammatory factors in APP/PS1 mice. Proteomics analysis reveals molecular changes in hippocampal proteins after ultrasound stimulation treatment. The mechanism behind ultrasound stimulation-induced modulation of microglial polarization may be related to changes in mitochondrial oxidative phosphorylation.

Avicularin Treatment Ameliorates Ischemic Stroke Damage by Regulating Microglia Polarization and its Exosomes via the NLRP3 Pathway.

Avicularin (AL), an ingredient of Banxia, has anti-inflammatory properties in cerebral disease and regulates polarization of macrophages, but its effects on ischemic stroke (IS) damage have not been studied. In vivo, AL was administered by oral gavage to middle cerebral artery occlusion/reperfusion (MCAO/R) C57BL/6J mice in doses of 1.25, 2.5, and 5 mg/kg/day for seven days, and, in vitro, AL was added to treat oxygen-glucose deprivation (OGD)-BV2 cells. Modified neurological severity score, Triphenyltetrazolium chloride (TTC) staining, brain-water-content detection, TdT-mediated dUTP nick-end labeling (TUNEL) assay, flow cytometry, immunofluorescence assay, Enzyme linked immunosorbent assay (ELISA), and Western-blot analysis were used to investigate the functions and mechanism of the effect of AL treatment on IS. The exosomes of AL-treated microglia were studied by transmission electron microscope (TEM), nanoparticle tracking analyzer (NTA), and Western-blot analysis. AL treatment reduced the neurological severity score, infarct volume, brain-water content, neuronal apoptosis, and the release of inflammatory factors, that were induced by MCAO/R. Notably, M2 microglia polarization was promoted but M1 microglia polarization was inhibited by AL in the ischemic penumbra of MCAO/R mice. Subsequently, anti-inflammatory and polarization-regulating effects of AL were verified in vitro. Suppressed NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome activation was found in the ischemic penumbra of animal and Oxygen-Glucose Deprivation/Reoxygenation (OGD/R) cells treated with AL, as evidenced by decreasing NLRP3-inflammasome-related protein and downstream factors. After AL treatment, the anti-apoptosis effect of microglial exosomes on OGD/R primary cortical neurons was increased. AL reduce inflammatory responses and neuron death of IS-associated models by regulating microglia polarization by the NLRP3 pathway and by affecting microglial exosomes.

Zinc sulfide nanoparticles serve as gas slow-release bioreactors for H2S therapy of ischemic stroke

Stroke is one of the leading causes of death and disability in the world. Ischemic stroke causes overproduction of reactive oxygen/nitrogen species (RONS) after reperfusion, triggering inflammatory responses that further leads to cell damage. In order to develop novel neuroprotective materials, we synthesized zinc sulfide nanoparticles (ZnS NPs) to function as gas slow-release bioreactors, showcasing stable and sustained H2S release while effectively removing RONS. In cultured cells, ZnS NPs can reduce the oxidative damage caused by oxygen-glucose deprivation and reoxygenation (OGD/R), promote the expression of p-AMPK, enhance microglia M2 polarization, decrease inflammatory factors and reduce neuronal apoptosis. Additionally, it increases the proliferation and migration of endothelial cells, promoting the formation of new neurovascular units by regulating the protein of p-AKT. In mice with ischemic stroke induced by middle cerebral artery occlusion/reperfusion (MCAO/R), ZnS NPs significantly reduce the infarct area and restore the mobility of mice owing to the slow release of H2S. In summary, our results indicate that ZnS NPs can be used as H2S slow-release bioreactors, offering a potentially innovative approach to treat ischemia-reperfusion injury caused by stroke.