P物质促进脑膜炎奈瑟菌诱导小胶质细胞表达COX-2

目的观察P物质(substance P,SP)对脑膜炎奈瑟菌抗原诱导小胶质细胞表达环氧化酶2(cyclooxygenase-2,COX-2)和产生前列腺素E2(PGE2)的影响。方法原代培养小胶质细胞,根据不同的实验目的分为3组:(1)空白对照组:仅加入培养基;(2)脑膜炎奈瑟菌抗原组:加入10μg/mL抗原作用8 h;(3)SP组:在抗原刺激的同时加入1 nM SP作用8 h。采用RT-PCR检测小胶质细胞中COX-2的表达情况,ELISA检测培养上清中PGE2的产生。结果小胶质细胞未经任何处理情况下,COX-2表达量极少。当用10μg/mL脑膜炎奈瑟菌抗原处理8 h后,COX-2明显增高。而同时加用1 nM SP作用后,COX-2表达进一步增多。10μg/mL抗原作用8 h即可诱导一定水平的PGE2表达。而加用1 nM SP后,PGE2水平明显高于抗原组。此外,小胶质细胞经SP受体拮抗剂L-703606处理后,SP对COX-2的协同作用消失。结论 P物质能促进脑膜炎奈瑟菌诱导小胶质细胞表达COX-2及产生PGE2,从而可能加重中枢神经系统的炎症反应。

Triptolide protects against 1-methyl-4-phenyl pyridinium-induced dopaminergic neurotoxicity in rats:Implication for immunosuppressive therapy in Parkinson’s disease

Objective Neuroinflammation with microglial activation has been implicated to have a strong association with the progressive dopaminergic neuronal loss in Parkinson＇s disease （PD）. The present study was undertaken to evaluate the activation profile of microglia in 1-methyl-4-phenyl pyridinium （MPP^＋）-induced hemiparkinsonian rats. Triptolide, a potent immunosuppressant and microglia inhibitor, was then examined for its efficacy in protecting dopaminergic neurons from injury and ameliorating behavioral disabilities induced by MPP^＋. Methods The rat model of PD was established by intranigral microinjection of MPP^＋. At baseline and on day 1, 3, 7, 14, 21 following MPP^＋ injection, the degree of microglial activation was examined by detecting the immunodensity of OX-42 （microglia marker） in the substantia nigra （SN）. The number of viable dopaminergic neurons was determined by measuring tyrosine hydroxylase （TH） positive neurons in the SN. Behavioral performances were evaluated by counting the number of rotations induced by apomorphine, calculating scores of forelimb akinesia and vibrissae-elicited forelimb placing asymmetry. Results Intranigral injection of MPP^＋ resulted in robust activa- tion of microglia, progressive depletion of dopaminergic neurons, and ongoing aggravation of behavioral disabilities in rats. Triptolide significantly inhibited microglial activation, partially prevented dopaminergic cells from death and improved behavioral performances. Conclusion These data demonstrated for the first time a neuroprotective effect of triptolide on dopaminergic neurons in MPP^＋ induced hemiparkinsonian rats. The protective effect of triptolide may, at least partially, be related to the inhibition of MPP^＋-induced microglial activation. Our results lend strong support to the use of immunosuppressive agents in the management of PD.

Thrombin-induced microglial activation contributes to the degeneration of nigral dopaminergic neurons in vivo

Objective To evaluate the role of thrombin-activated microglia in the neurodegeneration of nigral dopaminergic neurons in the rat substantia nigra （SN） in vivo. Methods After stereotaxic thrombin injection into unilateral SN of rats, immunostaining, reverse transcription polymerase chain reaction （RT-PCR） and biochemical methods were used to observe tyrosine hydroxylase （TH） irnmunoreactive positive cells, microglia activation, nitric oxide （NO） amount and inducible nitricoxide synthase （iNOS） expression. Results （1） Selective damage to dopaminergic neurons was produced after thrombin injection, which was evidenced by loss of TH imrnunostaining in time-dependent manner; （2） Strong microglial activation was observed in the SN; （3） RT-PCR demonstrated the early and transient expression of neurotoxic factors iNOS mRNA in the SN. Immunofluorescence results found that thrombin induced expression of iNOS in microglia. The NO production in the thrombininjected rats was significantly higher than that of controls （P 〈 0.05）. Conclusion Thrombin intranigral injection can injure the dopaminergic neurons in the SN. Thrombin-induced microglia activation precedes dopaminergic neuron degeneration, which suggest that activation of microglia and release of NO may play important roles in dopaminergic neuronal death in the SN.

Lipopolysaccharide-induced cerebral inflammatory damage and the therapeutic effect of platelet activating factor receptor antoganist

Objective To investigate lipopolysaccharide （LPS） induced acute cerebral inflammatory damage and the therapeutic effect of ginkgolide B （BN52021）. Methods Thirty Sprague-Dawley rats were randomly divided into 3 groups （n = 10 for each group）： Control group, Model group and Treatment group （treated with BN52021）. LPS were injected into the fourth ventricle of rat to make a neuroinflammatory murine model. Morris water maze was used to detect the learning and memory ability of rats; changes of synapse number and subcellular ultrastructures were observed under a transmission electron microscope; OX-42 positive microglia in the brain was detected by immunohistochemical method. Results The average escape latency in the Treatment group were significantly shortened than that in the Model group; and the percentage of swimming distance traveled in platform quadrant accounting for total distance increased markedly. The rough endoplasmic reticulum and polyribosomes in the Treatment group were more than that in the Model group, but the number of synapses seemed to have no obvious change. The number of OX-42 positive microglia in the Treatment group decreased markedly than that in the Model group, and the grey density of OX-42-positive cells increased significantly. Conclusion LPS can induce inflammatory damages to the brain, but the damage could be antagonized by BN52021. Platelet activating factor receptor antagonist may offer an effective therapy for neurodegeneration diseases.

Lipopolysaccharide preconditioning induces protection against lipopolysac-charide -induced neurotoxicity in organotypic midbrain slice culture

Objective To identify the protective effect of lipopolysaccharide （LPS） preconditioning against LPS-induced inflammatory damage in dopaminergic neurons of midbrain slice culture and the possible mechanisms. Methods After cultured in vitro for 14 d, the rat organotypic midbrain slices were pretreated with different concentrations （0, 1, 3, 6 or 10 ng/mL） of LPS for 24 h followed by treatment with 100 ng/mL LPS for 72 h. The whole slice viability was detelmined by measurement of the activity of lactic acid dehydrogenase （LDH）. Tyrosine hydroxylase-immunoreactive （TH-IR） neurons and CD 1 1 b/c equivalent-immunoreactive （OX-42-IR） microglia in the slices were observed by immunohistochemical method, and tumor necrosis factor-α （TNF-α levels in the culture media were detected by enzymelinked immunosorbent assays （ELISA）. Results In the slices treated with 100 ng/mL LPS for 72 h, the number of TH-IR neurons reduced from 191± 12 in the control slices to 46±4, and the LDH activity elevated obviously （P 〈 0.01）, along with remarkably increased number of OX-42-IR cells and production of TNF-α （P 〈 0.01）. Preconditioning with 3 or 6 ng/mL LPS attenuated neuron loss （the number of TH-IR neurons increased to 126± 12 and 180± 13, respectively） and markedly reduced LDH levels （P 〈 0.05）, accompanied by significant decreases of OX-42-IR microglia activation and TNF-α production （P 〈 0.05）. Conclusion Low-dose LPS preconditioning could protect dopaminergic neurons against inflammatory damage in rat midbrain slice culture, and inhibition of microglial activation and reduction of the proinflammatory factor TNF-α production may contribute to this protective effect. Further understanding the underlying mechanism of LPS preconditioning may open a new window for treatment of Parkinson＇s disease.

Cyclooxygenase-2 inhibitor inhibits hippocampal synaptic reorganization in pilocarpine-induced status epilepticus rats

Objective： To examine modulations caused by cyclooxygenase-2 （COX-2） inhibitors on altered microenvironments and overbalanced neurotransmitters in pilocarpine-induced epileptic status rats and to investigate possible mechanisms. Methods： Celecoxib （a COX-2 inhibitor） was administered 45 min prior to pilocarpine administration. The effects of COX-2 inhibitors on mlPSCs （miniature GABAergic inhibitory postsynaptic currents） of CA3 pyramidal cells in the hippocampus were recorded. Expressions of COX-2, c-Fos, newly generated neurons, and activated microgliosis were analyzed by immunohistochemistry, and expressions of c^-subunit of y-amino butyric acid （GABAA） receptors and mitogen-activated protein kinase/extracellular signal-regulated protein kinase （MAPK/ERK） activity were detected by Western blotting. Results： Pretreatment with celecoxib showed protection against pilocarpine-induced seizures. Celecoxib prevented microglia activation in the hilus and inhibited the abnormal neurogenesis and astrogliosis in the hippocampus by inhibiting MAPK/ERK activity and c-Fos transcription. Celecoxib also up-regulated the expression of GABAA receptors. NS-398 （N-2-cyclohexyloxy-4-nitrophenyl-methanesulfonamide）, another COX-2 inhibitor, enhanced the frequency and decay time of mIPSCs. Conclusion： The COX-2 inhibitor celecoxib decreased neuronal excitability and prevented epileptogenesis in pilocarpine-induced status epilepticus rats. Celecoxib regulates synaptic reorganization by inhibiting astrogliosis and ectopic neurogenesis by attenuating MAPK/ERK signal activity, mediated by a GABAergic mechanism.

D-β-hydroxybutyrate inhibits microglial activation in a cell activation model in vitro

Microglial activation plays an important role in a panel of neurological disorders such as multiple sclerosis(MS) and Parkinson's disease(PD),and is a key target for developing therapeutic strategies for these diseases.Ketogenic diet (KD),which is able to inhibit microglial activation in substantia nigra pars compacta of mice,has been shown effective in a mouse model of PD,possibly through increasing D-β-hydroxybutyrate(D-β-HB),a major component of ketone bodies.To verify this,we developed an in vitro model of microglia activation with a microglia line,BV-2,and investigated how D-β-HB have an effect on the LPS-stimulated BV-2 cells.We found D-β-HB is able to recover the cell viability,and inhibit the production of inflammatory mediators and cytokines such as ROS,nitrite,IL-1β,TNF-α,and IL-6,which otherwise were increased in LPS-stimulated BV-2 cells.We conclude that the LPS induced BV-2 cells activation is a valid in vitro model of microglia activation.D-β-HB is able to suppress the activation of BV-2 cells, which might account for one of the possible reasons of KD therapy on the PD model.

The therapeutic mechanism of Shenyuan Gan in lipopolysaccharide-induced neuroinflammation in BV2 microglial cells

Objective To study the therapeutic effects of Shenyuan Gan(参远苷,SYG)on the inflammat-ory response in BV2 microglial cells induced by lipopolysaccharide(LPS).Methods The cytotoxicity of SYG to BV2 microglial cells was evaluated using a Cell Counting Kit-8(CCK-8)assay,and the effect of SYG concentrations on LPS-induced BV2 microglial cells was studied.The morphological changes were observed using an optical microscope.The nitric oxide(NO)concentration in cell culture supernatant was determined using Griess re-agent.The expression of cytokines and inflammatory mediators were also measured by an en-zyme-linked immunosorbent assay(ELISA).Western blot analysis was used to determine the levels of inducible NO synthase(iNOS),nuclear factor-kappa B(NF-κB)p65,alpha inhibitor of NF-κB(IκB-α),phosphorylation-IκB-α(p-IκB-α),NOD-like receptor 3(NLRP3),and cas-pase-1 expression.Moreover,the expression of iNOS,NLRP3,and ionized calcium binding adapter molecule 1(Iba1)was also observed using immunofluorescent staining.Results SYG had a low cytotoxic effect on BV2 microglial cells and could significantly decr-ease LPS-induced morphological changes of BV2 microglial cells(P<0.05).ELISA results showed that SYG significantly inhibited the LPS-induced increase in interleukin(IL)-1βand IL-6 in BV2 microglia cells(P<0.05),and Western blot analysis showed that the phosphoryla-tion levels of iNOS,NF-κB p65,and IκB-αas well as NLRP3 and caspase-1 expression were also significantly decreased,and IκB-αexpression was increased after SYG treatment(P<0.05,compared with the LPS-treated group).The immunofluorescence results were consist-ent with the Western blot results,and Iba1 staining indicated that the cell morphology tended to be resting.These results indicate that SYG has a certain inhibitory effect on LPS-induced inflammation in BV2 microglial cells.Conclusion SYG can inhibit LPS-induced release of inflammatory factors in BV2 microglial cells by affecting the phosphorylation levels of NF-κB p65 and IκB-α.SYG is a valuable candid-ate for treating neuroinflammation-related diseases.

PrP 106-126 Altered PrP mRNA Gene Expression in Mouse Microglia BV-2 Cells

Prion diseases are infectious and fatal neurodegenerative diseases.The pathogenic agent is an abnormal prion protein aggregate.Microglial activation in the centre nervous system is a characteristic feature of prion disease.In this study,we examined the effect of PrP 106-126 on PrP mRNA gene expression in Mouse microglia cells BV-2 by real-time quantitative PCR.PrP mRNA expression level was found to be significantly increased after 18 h exposure of BV-2 cells to PrP 106-126,with 3-fold increase after 18 h and 4.5-fold increase after 24 h and BV-2 cells proliferating occurred correspondingly.Our results provide the first in vitro evidence of the increase of PrP mRNA levels in microglial cells exposed to PrP 106-126,and indicate that microglial cells might play a critical role in prion pathogenesis.

Maresin 1 alleviates neuroinflammation and cognitive decline in a mouse model of cecal ligation and puncture

Objective:Inflammation in the central nervous system plays a crucial role in the occurrence and development of sepsis-associated encephalopathy.This study aims to explore the effects of maresin 1(MaR1),an anti-inflammatory and pro-resolving lipid mediator,on sepsis-induced neuroinflammation and cognitive impairment.Methods:Mice were randomly assigned to 4 groups:A sham group(sham operation+vehicle),a cecal ligation and puncture(CLP)group(CLP operation+vehicle),a MaR1-LD group(CLP operation+1 ng MaR1),and a MaR1-HD group(CLP operation+10 ng MaR1).MaR1 or vehicle was intraperitoneally administered starting 1 h before CLP operation,then every other day for 7 days.Survival rates were monitored,and serum inflammatory cytokines[tumor necrosis factor alpha(TNF-α),interleukin(IL)-1β,and IL-6]were measured 24 h after operation using enzyme-linked immunosorbent assay(ELISA).Cognitive function was assessed 7 days after operation using the Morris water maze(MWM)test and novel object recognition(NOR)task.The mRNA expression of TNF-α,IL-1β,IL-6,inducible nitric oxide synthase(iNOS),IL-4,IL-10,and arginase 1(Arg1)in cortical and hippocampal tissues was determined by real-time reverse transcription PCR(RT-PCR).Western blotting was used to determine the protein expression of iNOS,Arg1,signal transducer and activator of transcription 6(STAT6),peroxisome proliferator-activated receptor gamma(PPARγ),and phosphorylated STAT6(p-STAT6)in hippocampal tissue.Microglia activation was visualized via immunofluorescence.Mice were also treated with the PPARγantagonist GW9662 to confirm the involvement of this pathway in MaR1’s effects.Results:CLP increased serum levels of TNF-α,IL-1β,and IL-6,and reduced body weight and survival rates(all P<0.05).Both 1 ng and 10 ng doses of MaR1 significantly reduced serum TNF-α,IL-1β,and IL-6 levels,improved body weight,and increased survival rates(all P<0.05).No significant difference in efficacy was observed between the 2 doses(all P>0.05).MWM test and NOR task indicated that CLP impaired spatial learning,which MaR1 mitigated.However,GW9662 partially reversed MaR1’s protective effects.Real-time RTPCR results demonstrated that,compared to the sham group,mRNA expression of TNF-α,IL-1β,and iNOS significantly increased in hippocampal tissues following CLP(all P<0.05),while IL-4,IL-10,and Arg1 showed a slight decrease,though the differences were not statistically significant(all P>0.05).Compared to the CLP group,both 1 ng and 10 ng MaR1 decreased TNF-α,IL-1β,and iNOS mRNA expression in hippocampal tissues and increased IL-4,IL-10,and Arg1 mRNA expression(all P<0.05).Immunofluorescence results indicated a significant increase in Iba1-positive microglia in the hippocampus after CLP compared to the sham group(P<0.05).Administration of 1 ng and 10 ng MaR1 reduced the percentage area of Iba1-positive cells in the hippocampus compared to the CLP group(both P<0.05).Western blotting results showed that,compared to the CLP group,both 1 ng and 10 ng MaR1 down-regulated the iNOS expression,while up-regulated the expression of Arg1,PPARγ,and p-STAT6(all P<0.05).However,the inclusion of GW9662 counteracted the MaR1-induced upregulation of Arg1 and PPARγcompared to the MaR1-LD group(all P<0.05).Conclusion:MaR1 inhibits the classical activation of hippocampal microglia,promotes alternative activation,reduces sepsis-induced neuroinflammation,and improves cognitive decline.

NMDA receptor antagonist MK-801 reduces neuronal damage and preserves learning and memory in a rat model of traumatic brain injury

Objective NMDA receptor channel plays an important role in the pathophysiological process of traumatic brain injury （TBI）. The present study aims to study the pathological mechanism of TBI and the impairment of learning and memory after TBI, and to investigate the mechanism of the protective effect of NMDA receptor antagonist MK-801 on learning and memory disorder after TBI. Methods Forty Sprague-Dawley rats （weighing approximately 200 g） were randomized into 5 groups （n = 8 in each group）： control group, model group, low-dose group （MK-801 0.5 mg/kg）, middle-dose group （MK-801 2 mg/kg）, and high-dose group （MK-801 10 mg/kg）. TBI model was established using a weight-drop head injury mode. After 2-month drug treatment, learning and memory ability was evaluated by using Morris water maze test. Then the animals were sacrificed, and brain tissues were taken out for morphological and immunohistochemical assays. Results The ability of learning and memory was significantly impaired in the TBI model animals. Besides, the neuronal caspase-3 expression, neuronal nitric oxide synthase （nNOS）-positive neurons and OX-42-positive microglia were all increased in TBI animals. Meanwhile, the number of neuron synapses was decreased, and vacuoles degeneration could be observed in mitochondria. After MK-801 treatment at 3 different dosages, the ability of learning and memory was markedly improved, as compared to that of the TBI model animals. Moreover, neuronal caspase-3 expression, OX-42-positive microglia and nNOS-positive neurons were all significantly decreased. Meanwhile, the mitochondria degeneration was greatly inhibited. Conclusion MK-801 could significantly inhibit the degeneration and apoptosis of neurons in damaged brain areas. It could also inhibit TBI-induced increase in nNOS-positive neurons and OX-42-positive microglia. Impairment in learning and memory in TBI animals could be repaired by treatment with MK-801.

P2Y6 receptor and immunoinflammation

The immunocytes microglia in the central nervous system （CNS） were reported to play a crucial role in neurodegeneration. As a member of P2 receptors family, purinoceptor P2Y6 has attracted much attention recently. Previous studies showed that purinoceptor P2Y6 mainly contributed to microglia activation and their later phagocytosis in CNS, while in immune system, it participated in the secretion of interleukin （IL）-8 from monocytes and macrocytes. So there raises a question： whether purinoceptor P2Y6 also takes part in neuroinflammation？ Thus, this review mainly concerns about the properties and roles of purinoceptor P2Y6, including （1） structure of purinoceptor P2Y6; （2） distribution and properties of purinoceptor P2Y6; （3） relationships between purinoceptor P2Y6 and microglia; （4） relationships between purinoceptor P2Y6 and immunoinflammation. It＇s proposed that purinoceptor P2Y6 may play a role in neuroinflammation in CNS, although further research is still required.

Targeting Wnt signaling at the neuroimmune interface for dopaminergic neuroprotectionJrepair in Parkinson＇s disease

During the past three decades, the Wingless-type MMTV integration site （Wnt） signaling cascade has emerged as an essential system regulating multiple processes in developing and adult brain. Accumulating evidence points to a dysregulation of Wnt signaling in major neurodegenerative pathologies including Parkinson＇s disease （PD）, a common neurodegenerative disorder characterized by the pro- gressive loss of midbrain dopaminergic （mDA） neurons and deregulated activation of astrocytes and microglia. This review highlights the emerging link between Wnt signaling and key inflammatory pathways during mDA neuron damage/repair in PD progression. In particular, we summarize recent evidence documenting that aging and neurotoxicant exposure strongly antagonize Wnt/β-catenin signaling in mDA neurons and subventricular zone （SVZ） neuroprogenitors via astrocyte-microglial interactions. Dysregulation of the crosstalk between Wnt/β-catenin signaling and anti-oxidant/anti-inflammatory pathways delineate novel mechanisms driving the decline of SVZ plasticity with age and the limited nigrostriatal dopaminergic self-repair in PD. These findings hold a promise in devetoping therapies that target Wnt/β-catenin signaling to enhance endogenous restoration and neuronal outcome in age-dependent diseases, such as PD.

Presenilin 2 deficiency facilitates Aβ-induced neuroinflammation and injury by upregulating P2X7 expression

Accumulating evidence suggests that β-amyloid （Aβ）-induced neuroinflammation plays a prominent and early role in Alzheimer＇s disease （AD）. In this study, we demonstrated that Presenilin 2 （PS2） deficiency facilitates Aβ-induced neuroinflammation and injury by upregulating P2X7 expression both in vitro and in vivo. PS2 knockout mice demonstrated increased cognitive impairments and cerebral injury. PS2 deficiency increased the expression of P2X7 both in neurons and microglial cells. Furthermore, extracellular ATP also increased in both Aβ-treated and untreated PS2 knockout microglial cells. Notably, Aβ-induced classical proinflammatory cytokines such as IL-113, IL-1α and TNF-α were increased in PS2 knockout microglial cells, suggesting a potential role for PS2 in the regulation of neuroinflammation. The expression of P2X7 clearly increased in PS2 knockdown BV2 cells. Consistent with in vivo data, Aβ-induced IL-1βproduction was also clearly enhanced in PS2 knockdown BV2 cells. Additionally, expression of the transcription factor Sp was increased in PS2 knockdown cells. When we treated PS2 knockdown ceils with the specific Spl inhibitor MIT, we observed that enhanced P2X7 expression was significantly rescued. Taken together, these data suggests that PS2 plays a protective role during Aβ-induced neuroinflammation and injury through down-regulation of P2X7 expression.

DGMI alleviates OGD/R-induced cell injury by regulating inflammatory and apoptosis signaling pathways

Diterpene ginkgolides meglumine injection(DGMI),a kind of Ginkgo biloba special extract injection,is now used for the treatment of ischemic stroke in convalescence.In the present study,we aimed to confirm whether DGMI could suppress inflammatory responses and apoptosis and explore the potential mechanisms underlying these effects.Cell viability and lactate dehydrogenase(LDH)release were measured by MTS and LDH assays after the cells were exposed to oxygen-glucose deprivation/reoxygenation(OGD/R).The extent of anti-apoptotic effect of DGMI was detected by flow cytometry using Annexin V-FITC/PI double staining assay kit.Pro-inflammatory cytokines,including TNF-α,IL-1β,IL-6 and IL-10,were quantified by a specific Bio-Plex ProTM Reagent Kit.Additionally,activities of TLR2/4,NF-κB p65,MAPK pathway and apoptosis-related proteins as well as cellular localization of NF-κB p65 were determined by Western blotting analysis and immunofluorescence staining,respectively.DGMI at 50μg/mL significantly increased the cell viability and decreased the secretion of IL-1β,IL-6,IL-10 and TNF-αin OGD/R-induced BV2 microglia cells.These effects were also confirmed by LDH assay and Annexin V-FITC/PI staining.Meanwhile,DGMI not only inhibited the protein expressions of TLR2,TLR4,MyD88,p-TAK1,p-IkBα,p-IKKβand Bak,but also decreased the cleaved caspase-3/caspase-3,Bax/Bcl-2 and cleaved PARP-1/PARP-1 ratio in OGD/R-induced BV2 microglia cells.Furthermore,OGD/R-enhanced p-JNK1/2 and p-p38 MAPK expressions and nuclear translocation of NF-κB p65 were also partially inhibited by DGMI.The present study showed that inflammatory responses were triggered in BV2 microglia cells activated by OGD/R,leading to the release of pro-inflammatory cytokines and apoptosis.DGMI suppressed the inflammatory response and apoptosis by regulating the TLR/MyD88/NF-κB signaling pathways and down-regulation of p-JNK1/2 and p-p38 MAPK activation.

Regulatory mechanisms and therapeutic potential of microglial inhibitors in neuropathic pain and morphine tolerance

Microglia are important cells involved in the regulation of neuropathic pain(NPP)and morphine tolerance.Information on their plasticity and polarity has been elucidated after determining their physiological structure,but there is still much to learn about the role of this type of cell in NPP and morphine tolerance.Microglia mediate multiple functions in health and disease by controlling damage in the central nervous system(CNS)and endogenous immune responses to disease.Microglial activation can result in altered opioid system activity,and NPP is characterized by resistance to morphine.Here we investigate the regulatory mechanisms of microglia and review the potential of microglial inhibitors for modulating NPP and morphine tolerance.Targeted inhibition of glial activation is a clinically promising approach to the treatment of NPP and the prevention of morphine tolerance.Finally,we suggest directions for future research on microglial inhibitors.

2-Hydroxycircumdatin C inhibits LPS-induced BV2 cells inflammatory response via down-regulation of TLR4-mediated NF-κB/MAPK and JAK2/STAT3 pathways

2-Hydroxycircumdatin C(2-HCC) is a circumdatin-type alkaloid isolated from a coral-associated fungus Aspergillus ochraceus LZDX-32-15.In the present study,we aimed to assess the neuroprotective effects of 2-HCC on the microglia-mediated inflammatory response as well as underlining molecular mechanisms.2-HCC could significantly down-regulate the overproduction of tumor necrosis factor-α(TNF-α) and interleukin-1β(IL-1β) induced by lipopolysaccharide(LPS) both in BV2 cells and primary microglial cells without affecting cell viability.In addition,2-HCC exerted obvious neuroprotective effects against inflammatory injury in neurons when cocultured with LPS-induced microglia.Mechanism investigation indicated that the anti-inflammatory effect of 2-HCC involved the inhibition of inducible nitric oxide synthase(iNOS) and cyclooxygenase 2(COX-2) and alleviation of the LPS-induced TLR4-NF-κB/MAPK pathway.Furthermore,2-HCC treatment attenuated LPS-induced activation of the JAK2/STAT3 pathway.In conclusion,these results indicated that the anti-inflammatory and neuroprotective properties of 2-HCC,at least partially,depended upon TLR4-NF-κB/MAPK and JAK2/STAT3 signaling pathways.

The role of microglia in thalamic reticular nucleus in acupuncture regulating cognitive deficits in insomnia rats

Objective:To explore the mechanism of acupuncture in regulating cognitive deficits in insomnia rats by observing the effect of acupuncture on microglia in thalamic reticular nucleus(TRN).Methods:Thirty rats were randomly divided into a control group,a model group and an acupuncture group,with 10 rats in each group.The insomnia model was established by intraperitoneal injection of para-chlorophenylalanine(PCPA)once a day for 2 d.Rats in the control group were intraperitoneally injected with the same amount of normal saline.Rats in the acupuncture group received acupuncture at Neiguan(PC 6)and Zusanli(ST 36)for 5 consecutive days.The CLOCKLAB 2 data acquisition system was used to dynamically observe the sleep of the rats throughout the experiment.The cognition of rats was evaluated by event-related potentials(ERPs).After intervention,brain tissue was extracted.Immunofluorescence was used to test the fluorescence expression in TRN region.The concentrations of interleukin(IL)-1βand tumor necrosis factor(TNF)-αwere detected by enzyme-linked immunosorbent assay.Results:After intraperitoneal injection of PCPA suspension,the spontaneous activity in light period of rats in the model group and acupuncture group increased significantly compared with the control group(both P<0.01).After acupuncture treatment,the rats in the acupuncture group had much less spontaneous activity during the light period than those in the model group(P<0.01),and the results indicated that acupuncture could effectively improve the sleep quality of insomnia rats.Compared with the control group,rats in the model group showed that the P3 latency,the average optical density of microglia,and the concentrations of IL-1βand TNF-αincreased significantly(all P<0.05),and the P3 amplitude decreased significantly(P<0.01).Compared with the model group,rats in the acupuncture group presented that the P3 latency,the average optical density of microglia,and the concentrations of IL-1βand TNF-αwere significantly decreased(all P<0.05),and the amplitude of P3 was significantly increased(P<0.05).Conclusion:Acupuncture possesses an ability to improve the cognitive state in insomnia rats.The mechanism may be related to inhibiting the microglial activation,diminishing the levels of pro-inflammatory mediators like IL-1βand TNF-α,and promoting the recovery of central nervous system function.

Human endogenous retrovirus W env increases nitric oxide production and enhances the migration ability of microglia by regulating the expression of inducible nitric oxide synthase

Human endogenous retrovirus W env(HERV-W env) plays a critical role in many neuropsychological diseases such as schizophrenia and multiple sclerosis(MS). These diseases are accompanied by immunological reactions in the central nervous system(CNS). Microglia are important immunocytes in brain inflammation that can produce a gasotransmitter – nitric oxide(NO). NO not only plays a role in the function of neuronal cells but also participates in the pathogenesis of various neuropsychological diseases. In this study, we reported increased NO production in CHME-5 microglia cells after they were transfected with HERV-W env. Moreover, HERV-W env increased the expression and function of human inducible nitric oxide synthase(hi NOS) and enhanced the promoter activity of hi NOS. Microglial migration was also enhanced. These data revealed that HERV-W env might contribute to increase NO production and microglial migration ability in neuropsychological disorders by regulating the expression of inducible NOS. Results from this study might lead to the identification of novel targets for the treatment of neuropsychological diseases, including neuroinflammatory diseases, stroke, and neurodegenerative diseases.

Interferon-liposomes prepared to make macroglia maintain M1 phenotype

Macroglia is a crucial macrophage only existing in the central nervous system.During the development of glioma,it can be activated as M2 anti-inflammatory type to promote glioma growth.Interferon-γ(IFN-γ)is an important immunomodulator in glioma microenvironment,which can also activate macroglia as M1 pro-inflammatory type to enhance anti-tumor immune response and lead to inhibition of glioma growth.Therefore,we utilized IFN-γto make macroglia maintain M1 phenotype,so that prospectively achieving anti-tumor immunity for glioma therapy.We prepared interferon-γ-liposomes(IFN-Lp)to protect IFN-γfrom elimination.IFN-Lp was proved to have strong capability to be phagocytosed and accumulate in macroglia(BV2 cells)to achieve long-term effect.In addition,IFN-Lp could allow BV2 cells to maintain M1 phenotype,showing no impact on its cell viability.These findings will offer new opportunities to achieve enhanced immunotherapy of glioma.