BV2 Microglia Research Articles

Rejuvenating aged microglia by p16ink4a-siRNA-loaded nanoparticles increases amyloid-β clearance in animal models of Alzheimer's disease.

Age-dependent accumulation of amyloid plaques in patients with sporadic Alzheimer's disease (AD) is associated with reduced amyloid clearance. Older microglia have a reduced ability to phagocytose amyloid, so phagocytosis of amyloid plaques by microglia could be regulated to prevent amyloid accumulation. Furthermore, considering the aging-related disruption of cell cycle machinery in old microglia, we hypothesize that regulating their cell cycle could rejuvenate them and enhance their ability to promote more efficient amyloid clearance. First, we used gene ontology analysis of microglia from young and old mice to identify differential expression of cyclin-dependent kinase inhibitor 2A (p16ink4a), a cell cycle factor related to aging. We found that p16ink4a expression was increased in microglia near amyloid plaques in brain tissue from patients with AD and 5XFAD mice, a model of AD. In BV2 microglia, small interfering RNA (siRNA)-mediated p16ink4a downregulation transformed microglia with enhanced amyloid phagocytic capacity through regulated the cell cycle and increased cell proliferation. To regulate microglial phagocytosis by gene transduction, we used poly (D,L-lactic-co-glycolic acid) (PLGA) nanoparticles, which predominantly target microglia, to deliver the siRNA and to control microglial reactivity. Nanoparticle-based delivery of p16ink4a siRNA reduced amyloid plaque formation and the number of aged microglia surrounding the plaque and reversed learning deterioration and spatial memory deficits. We propose that downregulation of p16ink4a in microglia is a promising strategy for the treatment of Alzheimer's disease.

Effects of the Glucocorticoid-Mediated Mitochondrial Translocation of Glucocorticoid Receptors on Oxidative Stress and Pyroptosis in BV-2 Microglia.

Microglia are resident macrophages within the central nervous system, serving as the first responders to neuroinflammation. Glucocorticoids (GCs) may cause damage to brain tissue, but the specific mechanism remains unclear. This study was divided into two parts: a glucocorticoid receptor (GR) mitochondrial translocation intervention experiment and a mitochondrial oxidative stress inhibition experiment. BV-2 microglia were stimulated with dexamethasone (DEX) and treated with either tubastatin-A or mitoquinone (MitoQ) for 24 h. Our results showed that DEX increased the translocation of GRs to mitochondria, and this effect was accompanied by decreases in the expression of mitochondrially encoded cytochrome c oxidase 1 (MT-CO1) and mitochondrially encoded cytochrome c oxidase 3 (MT-CO3) and increases in the expression of NOD-like receptor thermal protein domain-associated protein 3 (NLRP3), caspase-1, and Gasdermin D (GSDMD). The level of mitochondrial respiratory chain complex IV (MRCC IV) and adenosine triphosphate (ATP) was decreased. An elevation in the level of mitochondrial oxidative stress and the opening of the mitochondrial permeability transition pore (mPTP) was also observed. Mechanistically, tubastatin-A significantly suppressed the mitochondrial translocation of GRs, improved the expression of mitochondrial genes, promoted the restoration of mitochondrial function, and inhibited pyroptosis. MitoQ significantly prevented mitochondrial oxidative stress, improved mitochondrial function, and reduced apoptosis and pyroptosis. Both tubastatin-A and MitoQ suppressed DEX-induced pyroptosis. This study substantiates that the increase in the mitochondrial translocation of GRs mediated by GCs exacerbates oxidative stress and pyroptosis in microglia, which indicates that the regulation of mitochondrial pathways by GCs is pathogenic to microglia.

Polystyrene microplastics induce anxiety via HRAS derived PERK-NF-κB pathway

Exposure to environmentally hazardous substances is recognized as a significant risk factor for neurological associated disorders. Among these substances, polystyrene microplastics (PS-MPs), widely utilized in various consumer products, have been reported to exhibit neurotoxicity. However, the potential association of PS-MPs with abnormal anxiety behaviors, along with the underlying molecular mechanisms and key proteins involved, remains insufficiently explored. Here, we delineated the potential mechanisms of PS-MPs-induced anxiety through proteomics and molecular investigations. We characterized the PS-MPs, observed their accumulation in the brain, leading to anxiety-like behavior in mice, which is correlated with microglia activation and pro-inflammatory response. Consistent with these findings, our studies on BV2 microglia cells showed that PS-MPs activated NF-κB-mediated inflammation resulting in the upregulation of pro-inflammatory cytokines such as TNFα and IL-1β. Of particular significance, HRAS was identified as a key factor in the PS-MPs induced pro-inflammatory response through whole proteomics analysis, and knockdown of H-ras effectively inhibited PS-MPs induced PERK-NF-κB activation and associated pro-inflammatory response in microglia cells. Collectively, our findings highlight that PS-MPs induce anxiety of mice via the activation of the HRAS-derived PERK-NF-κB pathway in microlglia. Our results contribute valuable insights into the molecular mechanisms of PS-MPs-induced anxiety, and may offer implications for addressing neurotoxicity and prevention the adverse effects of environmentally hazardous substances, including microplastics.

Enhancing Solubility and Bioefficacy of Stilbenes by Liposomal Encapsulation-The Case of Macasiamenene F.

Stilbenes in food and medicinal plants have been described as potent antiphlogistic and antioxidant compounds, and therefore, they present an interesting potential for the development of dietary supplements. Among them, macasiamenene F (MF) has recently been shown to be an effective anti-inflammatory and cytoprotective agent that dampens peripheral and CNS inflammation in vitro. Nevertheless, this promising molecule, like other stilbenes and a large percentage of drugs under development, faces poor water solubility, which results in trickier in vivo administration and low bioavailability. With the aim of improving MF solubility and developing a form optimized for in vivo administration, eight types of conventional liposomal nanocarriers and one type of PEGylated liposomes were formulated and characterized. In order to select the appropriate form of MF encapsulation, the safety of MF liposomal formulations was evaluated on THP-1 and THP-1-XBlue-MD2-CD14 monocytes, BV-2 microglia, and primary cortical neurons in culture. Furthermore, the cellular uptake of liposomes and the effect of encapsulation on MF anti-inflammatory effectiveness were evaluated on THP-1-XBlue-MD2-CD14 monocytes and BV-2 microglia. MF (5 mol %) encapsulated in PEGylated liposomes with an average size of 160 nm and polydispersity index of 0.122 was stable, safe, and the most promising form of MF encapsulation keeping its cytoprotective and anti-inflammatory properties.

Ferroptosis mediated by TNFSF9 interferes in acute ischaemic stroke reperfusion injury with the progression of acute ischaemic stroke.

In this study, we investigated the potential involvement of TNFSF9 in reperfusion injury associated with ferroptosis in acute ischaemic stroke patients, mouse models and BV2 microglia. We first examined TNFSF9 changes in peripheral blood from stroke patients with successful reperfusion, and constructed oxygen-glucose deprivation-reperfusion (OGD-R) on BV2 microglia, oxygen-glucose deprivation for 6 h followed by reoxygenation and re-glucose for 24 h, and appropriate over-expression or knockdown of TNFSF9 manipulation on BV2 cells and found that in the case of BV2 cells encountering OGD-R over-expression of TNFSF9 resulted in increased BV2 apoptosis. Still, the knockdown of TNFSF9 ameliorated apoptosis and ferroptosis. In an invivo experiment, we constructed TNFSF9 over-expression or knockout mice by intracerebral injection of TNFSF9-OE or sh-TNFSF9 adenovirus. We performed the middle cerebral artery occlusion (MCAO) model on day four, 24 h after ligation of the proximal artery, for half an hour to recanalize. As luck would have it, over-expression of TNFSF9 resulted in increased brain infarct volumes, neurological function scores and abnormalities in TNFSF9-related TRAF1 and ferroptosis-related pathways, but knockdown of TNFSF9 improved brain infarcts in mice as well as reversing TNFSF9-related signalling pathways. In conclusion, our data provide the first evidence that TNFSF9 triggers microglia activation by activating the ferroptosis signalling pathway following ischaemic stroke, leading to brain injury and neurological deficits.

Albiflorin Attenuates Neuroinflammation and Improves Functional Recovery After Spinal Cord Injury Through Regulating LSD1-Mediated Microglial Activation and Ferroptosis.

Spinal cord injury (SCI) is a serious, prolonged, and irreversible injury with few therapeutic options. Albiflorin (AF) possesses powerful pharmacodynamic properties and exerts protective effects against neuroinflammation. However, no research has examined the neuroprotective effect of AF following SCI.Rats were received laminectomy to establish SCI animal model and treated with AF (20mg/kg and 40mg/kg). Behavioral experiments were conducted to assess the impacts of AF on motor function after SCI in rats. Hematoxylin-eosin (HE) staining, Nissl staining, and Prussian Blue staining were performed to observe histological changes, neuronal damage, and iron deposition, respectively. Transmission electron microscope was adopted to observe the ultrastructure of spinal cord tissues. Immunofluorescence assay was performed to examine neurons and microglia. ELISA assay was used to examine the production of cytokines. Western blot assay was used to detect the expression level of ferroptosis-related proteins. Microglia BV-2 cells were induced by LPS to mimic the neuroinflammatory condition. Cell viability was assessed by CCK-8 assay, and lipid peroxidase level was measured by C11 BODIPY 581/591 staining. Molecular docking technology was utilized to confirm the relationship between AF and LSD1.AF improved the motor functional recovery after SCI in rats. Meanwhile, AF attenuated neuron apoptosis and microglia activation, reduced the production of pro-inflammatory cytokines and iron accumulation, and inhibited spinal cord ferroptosis following SCI in rats. LSD1 was verified to be a target protein of AF, and AF could concentration-dependently downregulate LSD1 expression in injured spinal cordsin vivoand LPS-induced BV-2 cellsin vitro. In addition, AF not only inhibited ferroptosis through reducing lipid peroxidase and iron levels and regulating ferroptosis-related proteins, but also inhibited microglial activation and reduced pro-inflammatory cytokines production in LPS-induced BV-2 cells; however, these changes were partly counteracted by LSD1 overexpression.AF could reduce microglial activation and ferroptosis, attenuate neuroinflammation, and improve functional recovery following SCI by downregulating LSD1, providing novel therapeutic strategies for the treatment of SCI.

Activating astrocytic α2A adrenoceptors in hippocampus reduces glutamate toxicity to attenuate sepsis-associated encephalopathy in mice

BackgroundGlutamate metabolism disorder is an important mechanism of sepsis-associated encephalopathy (SAE). Astrocytes regulate glutamate metabolism. In septic mice, α2A adrenoceptor (α2A-AR) activation in the central nervous system provides neuroprotection. α2A-ARs are expressed abundantly in hippocampal astrocytes. This study was performed to determine whether hippocampal astrocytic α2A-AR activation confers neuroprotection against SAE and whether this protective effect is astrocyte specific and achieved by the modulation of glutamate metabolism. MethodsMale C57BL/6 mice with and without α2A-AR knockdown were subjected to cecal ligation and puncture (CLP). They were treated with intrahippocampal guanfacine (an α2A-AR agonist) or intraperitoneal dexmedetomidine in the presence or absence of dihydrokainic acid [DHK; a glutamate transporter 1 (GLT-1) antagonist] and/or UCPH-101 [a glutamate/aspartate transporter (GLAST) antagonist]. Hippocampal tissue was collected for the measurement of astrocyte reactivity, GLT-1 and GLAST expression, and glutamate receptor subunit 2B (GluN2B) phosphorylation. In vivo real-time extracellular glutamate concentrations in the hippocampus were measured by ultra-performance liquid chromatography tandem mass spectrometry combined with microdialysis, and in vivo real-time hippocampal glutamatergic neuron excitability was assessed by calcium imaging. The mice were subjected to the Barnes maze and fear conditioning tests to assess their learning and memory. Golgi staining was performed to assess changes in the hippocampal synaptic structure. In vitro, primary astrocytes with and without α2A-AR knockdown were stimulated with lipopolysaccharide (LPS) and treated with guanfacine or dexmedetomidine in the presence or absence of 8-bromo- cyclic adenosine monophosphate (8-Br-cAMP, a cAMP analog). LPS-treated primary and BV2 microglia were also treated with guanfacine or dexmedetomidine. Astrocyte reactivity, PKA catalytic subunit, GLT-1 an GLAST expression were determined in primary astrocytes. Interleukin-1β, interleukin-6 and tumor necrosis factor-alpha in the medium of microglia culture were measured. ResultsCLP induced synaptic injury, impaired neurocognitive function, increased astrocyte reactivity and reduced GLT-1 and GLAST expression in the hippocampus of mice. The extracellular glutamate concentration, phosphorylation of GluN2B at Tyr-1472 and glutamatergic neuron excitability in the hippocampus were increased in the hippocampus of septic mice. Intraperitoneal dexmedetomidine or intrahippocampal guanfacine administration attenuated these effects. Hippocampal astrocytes expressed abundant α2A-ARs; expression was also detected in neurons but not microglia. Specific knockdown of α2A-ARs in hippocampal astrocytes and simultaneous intrahippocampal DHK and UCPH-101 administration blocked the neuroprotective effects of dexmedetomidine and guanfacine. Intrahippocampal administration of DHK or UCPH-101 alone had no such effect. In vitro, guanfacine or dexmedetomidine inhibited astrocyte reactivity, reduced PKA catalytic subunit expression, and increased GLT-1 and GLAST expression in primary astrocytes but not in primary astrocytes that received α2A-AR knockdown or were treated with 8-Br-cAMP. Guanfacine or dexmedetomidine inhibited microglial reactivity in BV2 but not primary microglia. ConclusionsOur results suggest that neurocognitive protection against SAE after hippocampal α2A-AR activation is astrocyte specific. This protection may involve the inhibition of astrocyte reactivity and alleviation of glutamate neurotoxicity, thereby reducing synaptic injury. The cAMP/protein kinase A (PKA) signaling pathway is a potential cellular mechanism by which activating α2A-AR modulates astrocytic function.

Human β-Defensin 3 Inhibition of P. gingivalis LPS-Induced IL-1β Production by BV-2 Microglia through Suppression of Cathepsins B and L.

Cathepsin B (CatB) is thought to be essential for the induction of Porphyromonas gingivalis lipopolysaccharide (Pg LPS)-induced Alzheimer's disease-like pathologies in mice, including interleukin-1β (IL-1β) production and cognitive decline. However, little is known about the role of CatB in Pg virulence factor-induced IL-1β production by microglia. We first subjected IL-1β-luciferase reporter BV-2 microglia to inhibitors of Toll-like receptors (TLRs), IκB kinase, and the NLRP3 inflammasome following stimulation with Pg LPS and outer membrane vesicles (OMVs). To clarify the involvement of CatB, we used several known CatB inhibitors, including CA-074Me, ZRLR, and human β-defensin 3 (hBD3). IL-1β production in BV-2 microglia induced by Pg LPS and OMVs was significantly inhibited by the TLR2 inhibitor C29 and the IκB kinase inhibitor wedelolactonne, but not by the NLRPs inhibitor MCC950. Both hBD3 and CA-074Me significantly inhibited Pg LPS-induced IL-1β production in BV-2 microglia. Although CA-074Me also suppressed OMV-induced IL-1β production, hBD3 did not inhibit it. Furthermore, both hBD3 and CA-074Me significantly blocked Pg LPS-induced nuclear NF-κB p65 translocation and IκBα degradation. In contrast, hBD3 and CA-074Me did not block OMV-induced nuclear NF-κB p65 translocation or IκBα degradation. Furthermore, neither ZRLR, a specific CatB inhibitor, nor shRNA-mediated knockdown of CatB expression had any effect on Pg virulence factor-induced IL-1β production. Interestingly, phagocytosis of OMVs by BV-2 microglia induced IL-1β production. Finally, the structural models generated by AlphaFold indicated that hBD3 can bind to the substrate-binding pocket of CatB, and possibly CatL as well. These results suggest that Pg LPS induces CatB/CatL-dependent synthesis and processing of pro-IL-1β without activation of the NLRP3 inflammasome. In contrast, OMVs promote the synthesis and processing of pro-IL-1β through CatB/CatL-independent phagocytic mechanisms. Thus, hBD3 can improve the IL-1β-associated vicious inflammatory cycle induced by microglia through inhibition of CatB/CatL.

Elucidating the mechanisms underlying astrocyte-microglia crosstalk in hippocampal neuroinflammation induced by acute diquat exposure.

The transition from paraquat (PQ) to diquat (DQ), both organic dication herbicides, in China has led to significant increases in the number of acute DQ poisoning cases. Case studies have shown that acute DQ poisoning resulted in injury to the central nervous system (CNS), but the mechanism underlying the injury remains to be explored. The present study aimed to investigate how DQ influenced purinergic signaling between astrocytes and microglia and whether extracellular ATP (eATP) was involved in promoting neuroinflammation induced by acute DQ toxicity through the activation of the P2X4/NLRP3 signaling pathway. We constructed a rat model of acute DQ toxicity to observe the pathological changes in hippocampal tissues after DQ exposure and measure the expression levels of IL-1β and TNF-α in the hippocampal tissue. We also established an in vitro co-culture model of C6 astrocytes and BV-2 microglia using transwell chambers, measured the amount of eATP secreted into C6 astrocytes after DQ treatment, and assessed the inflammatory response and changes in the P2X4/NLRP3 signaling pathway in BV-2 microglia. The results showed that the neurons in the hippocampal tissue of rats exhibited loose arrangement, nuclear consolidation, and necrosis after DQ exposure, and IL-1β and TNF-α levels were signification higher in the hippocampal tissue after DQ exposure. DQ exposure to the co-cultured cells induced an increase in ATP secretion from C6 astrocytes as well as a significant increase of P2X4, NLRP3, IL-1β, and IL-18 expression in BV-2 microglia. In contrast, pretreatment of C6 astrocytes with apyrase (an ATP hydrolase) resulted in a significant decrease of P2X4, NLRP3, IL-1β, and IL-18 expression in BV-2 microglia. Furthermore, inhibition of P2X4 expression in BV-2 microglia by transfection with si-P2X4 effectively reversed the increase of NLRP3, IL-1β, and IL-18 in BV-2 microglia induced by DQ when co-cultured with C6 astrocytes. These results indicate that astrocytes can activate the P2X4/NLRP3 signaling pathway in microglia through the DQ-induced extracellular release of ATP to promote neuroinflammation in rat hippocampal tissue.

LncRNA PVT1 promotes neuroinflammation after intracerebral hemorrhage by regulating the miR-128-3p/TXNIP axis

Objective Intracerebral hemorrhage (ICH) has significant morbidity and mortality. TXNIP and the competing endogenous RNA (ceRNA) regulatory mechanism involved in long non-coding RNA (lncRNA) play roles in ICH. We probed the upstream microRNAs (miRNAs)/lncRNAs that regulated TXNIP expression in the ceRNA mechanism. Methods ICH mouse model was established, and ICH secondary injury was simulated in BV2 microglia by hemin treatment. TXNIP was silenced 48 h before ICH modeling. The ICH mouse brain water content (BWC) and brain lesion volume after ICH were recorded. Neuronal apoptosis and neurological deficits were evaluated by double staining of NeuN and TUNEL/modified Garcia/corner turn/forelimb placement tests. Iba1 + microglia number and tumor necrosis factor-α (TNF-α)/interleukin-1β (IL-1β)/IL-10/TXNIP/PVT1/miR-128-3p levels were assessed by immunohistochemistry, Western blot, ELISA, and RT-qPCR. Cell viability/death of BV2 cells conditioned medium-treated neuron HT22 cells were assessed by CCK-8/LDH assays. miRNA that had a targeted binding relationship with TXNIP was screened. The targeted bindings of miR-128-3p to TXNIP/PVT1 to miR-128-3p were verified by dual-luciferase reporter gene assay. Results TXNIP knockdown reduced post-ICH microglial activation/release of pro-inflammatory factors/brain edema/brain lesion volume/neurological deficits in mice and increased releases of anti-inflammatory factors. TXNIP/PVT1 knockdown inhibited hemin-induced inflammatory responses in BV2 cells and protected in vitro co-cultured HT22 cells. PVT1 was a sponge of miR-128-3p to repress TXNIP expression. miR-128-3p knockdown diminished PVT1 knockdown-inhibited hemin-induced BV2 cell inflammatory responses/neurotoxicity. Conclusions PVT1 silencing reduced hemin-induced neuroinflammation and had a protective effect on neurons by increasing the targeted inhibition of TXNIP by miR-128-3p.

Interferon Regulatory Factor 5 Regulates the Phagocytosis of Microglia and Alleviate Alzheimer's Pathology.

Microglia play a critical role in the pathophysiology of Alzheimer's disease. They are involved in Aβ-induced neuroinflammatory responses, regulating the production of inflammatory mediators. Interferon regulatory factor 5 (IRF5) plays a central role in inflammatory diseases in the periphery, the role of which in central nervous system remains elusive. This study aimed to investigate the role of IRF5 in Aβ-induced neuroinflammation and the progression of Aβ pathology. We found that Aβ1-42 oligomers significantly increased the level of IRF5 in BV2 microglia. The levels of proinflammatory cytokines TNF-α, IL-1β, and IL-6 were significantly upregulated with Aβ treatment. IRF5 knockdown with siRNA in microglia significantly reduced the expression of these proinflammatory factors induced by Aβ and promoted Aβ phagocytosis. Besides, LC3 upregulation and p62 downregulation were observed in IRF5 knockdown microglia. This was also validated in APP/PS1 mice with IRF5 knockdown, leading to reduced Aβ levels in the brain. We conclude that IRF5 mediates Aβ-induced microglial inflammatory responses. IRF5 knockdown attenuated Aβ-induced inflammatory responses and promoted the phagocytosis and autophagy of Aβ by microglia.

Dynamic Changes and Effects of H2S, IGF-1, and GH in the Traumatic Brain Injury.

The aim of this study was to examine the expression changes of H2S, IGF-1, and GH in traumatic brain injury (TBI) patients and to detect their neuroprotective functions after TBI. In this study, we first collected cerebrospinal fluid (CSF) and plasma from TBI patients at different times after injury and evaluated the concentrations of H2S, IGF-1, and GH. In vitro studies were using the scratch-induced injury model and cell-cell interaction model (HT22 hippocampal neurons co-cultured with LPS-induced BV2 microglia cells). In vivo studies were using the controlled cortical impact (CCI) model in mice. Cell viability was assessed by CCK-8 assay. Pro-inflammatory cytokines expression was determined by qRT-PCR, ELISA, and nitric oxide production. Western blot was performed to assess the expression of CBS, CSE, IGF-1, and GHRH. Moreover, the recovery of TBI mice was evaluated for behavioral function by applying the modified Neurological Severity Score (mNSS), the Rotarod test, and the Morris water maze. We discovered that serum H2S, CSF H2S, and serum IGF-1 concentrations were all adversely associated with the severity of the TBI, while the concentrations of IGF-1 and GH in CSF and GH in the serum were all positively related to TBI severity. Experiments in vitro and in vivo indicated that treatment with NaHS (H2S donor), IGF-1, and MR-409 (GHRH agonist) showed protective effects after TBI. This study gives novel information on the functions of H2S, IGF-1, and GH in TBI.

Hysterolides A–I, dimeric or monomeric sesquiterpene lactones from Parthenium hysterophorus L.

Nine undescribed sesquiterpene lactones, including two pseudoguaianolide dimers (1 and 2), a pseudoguaiac dilactone (3), and six pseudoguaianolides (4–9), along with 13 known analogues (10–22) were isolated from Parthenium hysterophorus. Among them, hysterolide A (1) possesses an unusual carbon skeleton with a unique cyclobutane ring connecting two pseudoguaianolides. Hysterolide C (3) is a sesquiterpene dilactone incorporating a bicyclo[5.1.0]octane core. Spectroscopic analyses, 13C NMR and ECD calculations, and X-ray diffraction elucidated their structures and absolute configurations. Moreover, all the isolates were assayed for their anti-inflammatory activities by inhibiting LPS-induced nitric oxide production in BV-2 microglia cells, wherein, nine compounds displayed significant inhibitory activities with IC50 of 0.52–6.32 μM. Furthermore, the preliminary structure-activity relationship was also established.

Nanotechnology for microglial targeting and inhibition of neuroinflammation underlying Alzheimer’s pathology

BackgroundAlzheimer's disease (AD) is considered to have a multifactorial etiology. The hallmark of AD is progressive neurodegeneration, which is characterized by the deepening loss of memory and a high mortality rate in the elderly. The neurodegeneration in AD is believed to be exacerbated following the intercoupled cascades of extracellular amyloid beta (Aβ) plaques, uncontrolled microglial activation, and neuroinflammation. Current therapies for AD are mostly designed to target the symptoms, with limited ability to address the mechanistic triggers for the disease. In this study, we report a novel nanotechnology based on microglial scavenger receptor (SR)-targeting amphiphilic nanoparticles (NPs) for the convergent alleviation of fibril Aβ (fAβ) burden, microglial modulation, and neuroprotection.MethodsWe designed a nanotechnology approach to regulate the SR-mediated intracellular fAβ trafficking within microglia. We synthesized SR-targeting sugar-based amphiphilic macromolecules (AM) and used them as a bioactive shell to fabricate serum-stable AM–NPs via flash nanoprecipitation. Using electron microscopy, in vitro approaches, ELISA, and confocal microscopy, we investigated the effect of AM–NPs on Aβ fibrilization, fAβ-mediated microglial inflammation, and neurotoxicity in BV2 microglia and SH-SY5Y neuroblastoma cell lines.ResultsAM–NPs interrupted Aβ fibrilization, attenuated fAβ microglial internalization via targeting the fAβ-specific SRs, arrested the fAβ-mediated microglial activation and pro-inflammatory response, and accelerated lysosomal degradation of intracellular fAβ. Moreover, AM–NPs counteracted the microglial-mediated neurotoxicity after exposure to fAβ.ConclusionsThe AM–NP nanotechnology presents a multifactorial strategy to target pathological Aβ aggregation and arrest the fAβ-mediated pathological progression in microglia and neurons.Graphical

Insulin Mediates Lipopolysaccharide-Induced Inflammatory Responses and Oxidative Stress in BV2 Microglia.

Insulin, the key hormone for glucose regulation, has garnered attention for its role as an immune modulator. Impaired insulin signaling in the central nervous system is linked to neuroinflammation and neurodegenerative diseases. Microglia, the resident macrophage-like immune cells in the brain, are key regulators of neuroinflammation. However, the mechanisms by which insulin influences microglial immune responses remain relatively unknown. This study aimed to assess the effects of post-treatment with insulin [30minutes after lipopolysaccharide (LPS) exposure] on LPS-induced inflammatory responses in BV2 microglial cells. Post-treatment with insulin potentiated LPS-induced production of nitric oxide and pro-inflammatory cytokines, such as TNF and IL-6, through activation of the Akt/NF-κB pathway. Insulin also enhanced the ability of BV2 cells to phagocytose bacteria particles and β-amyloid fibrils. Conversely, insulin inhibited activation of NADPH oxidase and reduced intracellular levels of reactive oxygen species in LPS-treated BV2 cells. Insulin enhances microglial immune competence when challenged by endotoxins but mitigates oxidative stress in these cells.

Fatsia japonica extract exerts antioxidant and anti-neuroinflammatory effects on neuronal cells and a zebrafish model

Ethnopharmacological relevanceFatsia japonica is a traditional medicine used to treat various diseases, including inflammation-related disorders. However, its antineuroinflammatory and neuroprotective effects remain unclear. Aim of the studyWe aimed to evaluate the anti-neuroinflammatory and neuroprotective effects of F. japonica extract to identify the underlying mechanisms. Materials and methodsThe components of F. japonica extract were profiled using ultra-high-performance liquid chromatography-mass spectrometry. The effects of F. japonica extract were investigated in BV2 microglia and HT22 hippocampal cells. Furthermore, in vivo effects of F. japonica extract were assessed using zebrafish models treated with H2O2 and LPS to evaluate the effects of in vivo. ResultsWe identified 27 compounds in the F. japonica extract. F. japonica extract demonstrated anti-inflammatory properties by suppressing LPS-induced inflammatory responses in both BV2 cells and zebrafish, along with inhibiting the activation of the nuclear factor (NF)-κB (p65) pathway. The protective effects of this extract were also observed on glutamate-treated HT22 cells and in H2O2-induced zebrafish. Furthermore, F. japonica extract upregulated nuclear factor E2-related (Nrf) 2/heme oxygenase (HO)-1 expression in BV2 and HT22 cells. ConclusionsF. japonica extract exerted anti-neuroinflammatory and neuroprotective effects through Nrf2/HO-1 and the NF-κB pathway.

Troxerutin dampened hypothalamic neuroinflammation via microglial IL-22/IL-22R1/IRF3 activation in dihydrotestosterone-induced polycystic ovary syndrome rats

BackgroundPolycystic ovary syndrome (PCOS) is the most common reproductive-endocrine condition in premenopausal women. Troxerutin, a common clinical anti-coagulant agent, was shown to work as a strong IL-22 boosting agent counteracting the hyperactivated gonadotrophin releasing hormone (GnRH) neurons and heightened GnRH release, the neuroendocrine origin of PCOS with unknown mechanism in rats. Exploring the off-label use of troxerutin medication for PCOS is thus sorely needed. MethodsSerum IL-22 content and hypothalamic IL-22 protein were detected. Inflammatory factor levels in hypothalamo-pituitary were evaluated. Immunofluorescence staining was employed to determine the activation and M1/M2-prone polarization of microglia in arcuate hypothalamus and median eminence. RNA-sequencing and transcriptome analysis were applied to explore the potential driver of microglia M2-polarization in response to IL-22 bolstering effect. The function of microglial IL-22/IL-22R1/IRF3 system was further verified using in vivo knockdown of IL-22R1 and a potent IRF3 inhibitor in BV2 microglial cell lines in vitro. ResultsTroxerutin augmented serum IL-22 content, and its consequent spillover into the hypothalamus led to the direct activation of IL-22R1/IRF3 system on microglia, thereby promoted microglia M2 polarization in arcuate hypothalamus and median eminence, dampened hypothalamic neuroinflammation, inhibited hyperactive GnRH and rescued a breadth of PCOS-like traits in dihydrotestosterone (DHT) rats. The salutary effects of troxerutin treatment on hypothalamic neuroinflammation, microglial M1/2 polarization, GnRH secretion and numerous PCOS-like features were blocked by in vivo knockdown of IL-22R1. Moreover, evidence in vitro illustrated that IL-22 supplement to BV-2 microglia cell lines promoted M2 polarization, overproduction of anti-inflammatory marker and limitation of pro-inflammatory factors, whereas these IL-22 effects were blunted by geldanamycin, a potent IRF3 inhibitor. ConclusionHere, the present study reported the potential off-label use of troxerutin medication, a common clinical anti-coagulant agent and an endogenous IL-22 enhancer, for multiple purposes in PCOS. The rational underlying the application of troxerutin as a therapeutic choice in PCOS derived from its activity as an IL-22 memetic agent targeting the neuro-endocrine origin of PCOS, and its promotive impact on microglia M2 polarization via activating microglial IL-22R1/IRF3 system in the arcuate hypothalamus and median eminence of DHT female rats.

Empagliflozin targets Mfn1 and Opa1 to attenuate microglia-mediated neuroinflammation in retinal ischemia and reperfusion injury

BackgroundNeuroinflammation and mitochondrial dysfunction play crucial roles in retinal ischemia and reperfusion (IR) injury. Recent studies have identified mitochondrial function as a promising target for immunomodulation. Empagliflozin (EMPA), an anti-diabetic drug, has exhibited great potential as both an anti-inflammatory agent and a protector of mitochondrial health. This study aimed to assess the therapeutic efficacy of EMPA in retinal IR injury.MethodsTo evaluate the protective effects of EMPA, the drug was injected into the vitreous body of mice post-retinal IR. Single-cell RNA sequencing (scRNA-seq) analysis was conducted to uncover the underlying mechanisms, and the results were further validated through in vivo and in vitro experiments.ResultsEMPA effectively protected retinal ganglion cells (RGCs) from IR injury by attenuating local retinal inflammation. The scRNA-seq analysis revealed that EMPA downregulated the nucleotide-binding domain and leucine-rich repeat containing protein 3 (NLRP3) signaling pathway and restored mitochondrial dynamics by upregulating the expression of mitochondrial fusion-related genes, Mitofusin 1 (Mfn1) and optic atrophy 1 (Opa1). These findings were further corroborated by Western blotting. In vitro experiments provided additional insights, demonstrating that EMPA suppressed lipopolysaccharide (LPS)-induced cell inflammation and NLRP3 inflammasome activation. Moreover, EMPA enhanced mitochondrial fusion, neutralized mitochondrial reactive oxygen species (mtROS), and restored mitochondrial membrane potential (MMP) in BV2 microglia. Notably, genetic ablation of Mfn1 or Opa1 abolished the anti-inflammatory effects of EMPA.ConclusionsOur findings highlight the positive contribution of Mfn1 and Opa1 to the anti-inflammatory therapeutic effect of EMPA. By restoring mitochondrial dynamics, EMPA effectively mitigates microglia-mediated neuroinflammation and prevents RGC loss in retinal IR injury.

Lumbricus Extract Prevents LPS-Induced Inflammatory Activation of BV2 Microglia and Glutamate-Induced Hippocampal HT22 Cell Death by Suppressing MAPK/NF-κB/NLRP3 Signaling and Oxidative Stress.

Microglia-induced inflammatory signaling and neuronal oxidative stress are mutually reinforcing processes central to the pathogenesis of neurodegenerative diseases. Recent studies have shown that extracts of dried Pheretima aspergillum (Lumbricus) can inhibit tissue fibrosis, mitochondrial damage, and asthma. However, the effects of Lumbricus extracts on neuroinflammation and neuronal damage have not been previously studied. Therefore, to evaluate the therapeutic potential of Lumbricus extract for neurodegenerative diseases, the current study assessed the extract's anti-inflammatory and antioxidant activities in BV2 microglial cultures stimulated with lipopolysaccharide (LPS) along with its neuroprotective efficacy in mouse hippocampal HT22 cell cultures treated with excess glutamate. Lumbricus extract dose-dependently inhibited the LPS-induced production of multiple proinflammatory cytokines (tumor necrosis factor-α, interleukin (IL)-6, and IL-1β) and reversed the upregulation of proinflammatory enzymes (inducible nitric oxide synthase and cyclooxygenase-2). Lumbricus also activated the antioxidative nuclear factor erythroid 2-relayed factor 2/heme oxygenase-1 pathway and inhibited LPS-induced activation of the nuclear factor-κB/mitogen-activated protein kinases/NOD-like receptor family pyrin domain containing 3 inflammatory pathway. In addition, Lumbricus extract suppressed the glutamate-induced necrotic and apoptotic death of HT22 cells, effects associated with upregulated expression of antiapoptotic proteins, downregulation of pro-apoptotic proteins, and reduced accumulation of reactive oxygen species. Chromatography revealed that the Lumbricus extract contained uracil, hypoxanthine, uridine, xanthine, adenosine, inosine, and guanosine. Its effects against microglial activation and excitotoxic neuronal death reported herein support the therapeutic potential of Lumbricus for neurodegenerative diseases.

MiR-99b-3p/Mmp13 axis regulates NLRP3 inflammasome-dependent microglial pyroptosis and alleviates neuropathic pain via the promotion of autophagy

BackgroundNeuropathic pain significantly impairs quality of life, and effective interventions are limited. NOD-like receptor thermal protein domain associated protein 3 (NLRP3)-mediated microglial pyroptosis and the subsequent proinflammatory cytokine production are critical in exacerbating pain. Considering microglial pyroptosis as a potential target for developing specific analgesic interventions for neuropathic pain, our study investigated the pathogenesis and therapeutic targets in this condition. MethodsIn vitro experiments involved the co-culture of the immortalized BV-2 microglia cell line with lipopolysaccharide (LPS) to induce microglial pyroptosis. Differentially expressed microRNAs (miRNAs) were identified using high-throughput sequencing analysis. The downstream target genes of these miRNAs were determined through Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases, and the downstream target genes, combined with miRNAs, were predicted and verified through dual luciferase reporter gene assays. In vivo experiments were conducted to construct a chronic constriction injury (CCI) neuropathic pain model in rats and evaluate the analgesic effects of intrathecal injection of an adeno-associated virus vector (AAV) carrying miR-99b-3p. Gene expression was modulated through mimic or siRNA transfection. Western blot analysis assessed the expression of microglial pyroptosis and autophagy-related proteins, whereas RT-qPCR measured changes in proinflammatory cytokines expression. ResultsLPS-stimulated up-regulation of proinflammatory cytokines in microglia, accompanied by NLRP3-dependent pyroptosis, including increased NLRP3, GSDMD-N, Caspase1-p20, and mature-IL-1β expression. High-throughput sequencing analysis revealed 16 upregulated and 10 downregulated miRNAs in LPS-stimulated microglia, with miR-99b-3p being the most downregulated. KEGG analysis revealed that the target genes of these miRNAs are primarily enriched in calcium, FoxO, and mitogen-activated protein kinase (MAPK) signal pathways. Furthermore, overexpression of miR-99b-3p through mimic transfection significantly inhibited the inflammatory response and NLRP3-mediated pyroptosis by promoting autophagy levels in activated microglia. In addition, we predicted that the 3′ untranslated region (UTR) of matrix metalloproteinase-13 (Mmp13) could bind to miR-99b-3p, and knockdown of Mmp13 expression through siRNA transfection similarly ameliorated enhanced proinflammatory cytokines expression and microglial pyroptosis by enhancing autophagy. In vivo, Mmp13 was co-localized with spinal dorsal horn microglia and was suppressed by intrathecal injection of the AAV-miR-99b-3p vector. Moreover, overpressed miR-99b-3p alleviated CCI-induced mechanical allodynia and neuroinflammation while suppressing pyroptosis by enhancing autophagy in the spinal cord of CCI rats. ConclusionmiR-99b-3p exerts analgesic effects on neuropathic pain by targeting Mmp13. These antinociceptive effects are, at least in part, attributed to the promotion of autophagy, thereby inhibiting neuroinflammation and NLRP3-mediated pyroptosis in activated microglia.