Dalesconols B inhibits lipopolysaccharide induced inflammation and suppresses NF-κB and p38/JNK activation in microglial cells

Prolactin Attenuates Neuroinflammation in LPS-Activated SIM-A9 Microglial Cells by Inhibiting NF-κB Pathways Via ERK1/2

Prolactin (PRL) is a pleiotropic hormone with multiple functions in several tissues and organs, including the brain. PRL decreases lesion-induced microgliosis and modifies gene expression related to microglial functions in the hippocampus, thereby providing a possible mechanism through which it might participate in neuroimmune modulatory responses and prevent neuronal cell damage. However, the direct contribution of microglial cells to PRL-mediated neuroprotection is still unclear and no studies have yet documented whether PRL can directly activate cellular pathways in microglial cells. The aim of this study is to elucidate in vitro actions of PRL on the immortalized SIM-A9 microglia cell line in basal and LPS-stimulated conditions. PRL alone induced a time-dependent extracellular signal-regulated kinase 1/2 (ERK1/2) activation. Pretreatment with PRL attenuated LPS (200 ng/ml) stimulated pro-inflammatory markers: nitric oxide (NO) levels, inducible nitric oxide synthase (iNOS), interleukins (IL)-6, -1β and tumor necrosis factor (TNF-α) expression at 20 nM dosage. PRL suppressed LPS-induced nuclear factor (NF)-κappaB (NF-κB) p65 subunit phosphorylation and its upstream p-ERK1/2 activity. In conclusion, PRL exhibits anti-inflammatory effects in LPS-stimulated SIM-A9 microglia by downregulating pro-inflammatory mediators corresponding to suppression of LPS-activated ERK1/2 and NF-κB phosphorylation.

Oxiracetam Mediates Neuroprotection Through the Regulation of Microglia Under Hypoxia-Ischemia Neonatal Brain Injury in Mice

In neonatal hypoxic-ischemic brain damage (HIBD), in addition to damage caused by hypoxia and ischemia, over-activation of inflammation leads to further deterioration of the condition, thus greatly shortening the optimal treatment time window. Ischemic penumbra, the edematous area encompassing the infarct core, is characterized by typical activation of microglia and overt inflammation, and prone to incorporate into the infarct core gradually after ischemia onset. If treated in time, the cells located in the penumbra can survive, thereby impeding the expansion of the infarction. We demonstrated for the first time that in the acute phase of HIBD in neonatal mice, treatment of Oxiracetam (ORC) significantly curtailed the size of ischemic penumbra together with drastic reduction of infarction. By staining various cellular markers, we found that the penumbra was defined and concentrated with activated microglia. We also analyzed transmission electron microscopy and Luminex assay results to elucidate the mechanisms involved. We further confirmed that ORC switched polarization of microglia from the inflammatory towards the alternatively activated phenotype, thus promoting microglia from being neurotoxic into neuroprotective. Meanwhile, ORC decreased proliferation of microglia; however, their functions of phagocytosis and autophagy were otherwise enhanced. Last, we clarified that ORC promoted autophagy through the AMPK/mTOR pathway, which further induced the transition of the inflammatory to the alternatively activated phenotype in microglia. The pro-inflammatory factors secretion was inhibited as well, thereby reducing the progression of the infarction. Taken together, it is concluded that Oxiracetam reduced the expansion of ischemic infarction in part via regulating the interplay between microglia activation and autophagy, which would delay the progression of HIBD and effectively prolong the time window for the clinical treatment of HIBD.

Reduced brain fractalkine-CX3CR1 signaling is involved in the impaired cognition of streptozotocin-treated mice

Patients with diabetes mellitus are predisposed to cognitive impairment. Fractalkine-CX3CR1 in the brain signaling represents a primary neuron-microglia inter-regulatory system for several brain functions including learning and memory processes. The present study addressed whether fractalkine-CX3CR1 signaling in the hippocampus contributes to the cognitive deficits observed in streptozotocin (STZ)-treated mice. Our results showed that STZ-treated mice exhibited significant cognitive deficits in the Y-maze test, and a decrease in fractalkine and CX3CR1 levels in the hippocampus. Moreover, intracerebroventricular injection of the CX3CR1 antagonist 18a in normal mice induced significant cognitive deficits in the Y-maze test. STZ-treated mice showed a significant increase in plasma corticosterone levels and a decrease in plasma and hippocampal levels of insulin-like growth factor-1 (IGF-1). Therefore, we examined the effects of corticosterone and IGF-1 on regulation of fractalkine and CX3CR1 expression. Dexamethasone (DEX) application significantly decreased the mRNA expression of fractalkine in primary neuron and astrocyte cultures, and of CX3CR1 in primary microglia cultures. On the other hand, IGF-1 application significantly increased the mRNA expression of fractalkine in primary neuron cultures and CX3CR1 in primary microglia cultures. In addition, administration of DEX and the IGF-1 receptor tyrosine kinase inhibitor picropodophyllin significantly reduced the mRNA expression of fractalkine and CX3CR1 in the hippocampus. These findings indicate that impaired cognition in STZ-treated mice is associated with reduced fractalkine-CX3CR1 signaling in the hippocampus which may be induced by an increase in corticosterone and a decrease in IGF-1.

6-Gingerol attenuates microglia-mediated neuroinflammation and ischemic brain injuries through Akt-mTOR-STAT3 signaling pathway

Neuroinflammation is critical for the pathogenesis of ischemia brain damage. Over-activated microglia-mediated inflammation plays a very important role in ischemia cerebral injuries. 6-Gingerol, obtained from edible ginger (Zingiber Officinale) exhibits protective effects against inflammation. In this study, we found that 6-Gingerol could reduce the size of infarction (P = 0.0184) and improve neurological functions (P = 0.04) at the third day after ischemic brain injury in vivo. Since 6-Gingerol has the anti-inflammatory effects, we further investigated its impacts on neuroinflammation mediated by microglia both in vivo and in vitro. We found that the levels of pro-inflammatory cytokines Interleukin-1 beta (IL-1β, P = 0.0213), Interleukin-6 (IL-6, P = 0.0316), and inducible NO synthase (iNOS, P = 0.0229) in the infarct penumbra were lower in 6-Gingerol treated groups. Furthermore, microglia induced pro-inflammatory cytokines, such as IL-6, IL-1β, incremental intercellular nitric oxide (NO), as well as iNOS were blocked by the treatment of 6-Gingerol in lipopolysaccharide (LPS) stimulated microglia. In terms of mechanism, 6-Gingerol potently suppressed phosphorylation of serine-threonine protein kinase (Akt) - mammalian target of rapamycin (mTOR) - signal transducer and activator of transcription 3 (STAT3) in LPS-treated microglia. Taken together, the present study suggested that 6-Gingerol improved cerebral ischemia injury by suppressing microglia-mediated neuroinflammation by down-regulating Akt-mTOR-STAT3 pathway.

Abnormal Iodine Nutrition-Induced ER Stress Upregulates MCP-1 Expression Through P38/MAPK Signaling Pathway in Thyroid Cells

Iodine is an important chemical for thyroid hormone synthesis. The association between iodine nutrition status and the risk of disease present U-shaped curve, as either low or high iodine nutrition status will increase the risk of thyroid diseases. Endoplasmic reticulum stress (ER stress), which can induce over expressions of inflammation factors, like monocyte chemo-attractant protein-1 (MCP-1), is related to the pathogenesis of thyroid disease. However, the correlations among iodine, MCP-1 and ER stress are not entirely clear during the pathogenesis of thyroid diseases. Present study aims to investigate how iodine nutrition status influences MCP-1 expression through P38/MAPK pathway as well as the roles of ER stress in this process. Human thyroid cells (Nthy-ori-3-1) was used as a cell model in this study. The expressions of p-P38, PERK, IRE1, ATF6, and MCP-1 were detected after the cells were treated with iodine at different concentrations with or without ER stress inhibitor (4-PBA) or P38/MAPK blocker (SB203580). The expressions of p-P38, PERK, IRE1, ATF6, and MCP-1 in Nthy-ori-3-1 cells treated with iodine at abnormal concentrations were all significantly higher than those in cells treated with iodine at normal concentration. However, addition of ER stress blocker, 4-PBA in the abnormal-iodine treated cells, decreased the expressions of p-P38, PERK, IRE1, ATF6, and MCP-1. Similarly, P38/MAPK activity inhibitor, SB203580, also decreased the expressions of p-P38 and MCP-1. Abnormal iodine nutrition status triggered ER stress and upregulated MCP-1 expression through P38/MAPK signaling pathway in thyrocyte.

Bakuchiol Suppresses Inflammatory Responses Via the Downregulation of the p38 MAPK/ERK Signaling Pathway

The purpose of the present study was to evaluate the effects of bakuchiol on the inflammatory response and to identify the molecular mechanism of the inflammatory effects in a lipopolysaccharide (LPS)-stimulated BV-2 mouse microglial cell line and mice model. The production of prostaglandin E₂ (PGE₂), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) was measured by enzyme-linked immunosorbent assay. The mRNA expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), TNF-α, and IL-6 was measured using reverse transcription–polymerase chain reaction analysis. Mitogen-activated protein kinase (MAPK) phosphorylation was determined by western blot analysis. In vitro experiments, bakuchiol significantly suppressed the production of PGE₂ and IL-6 in LPS-stimulated BV-2 cells, without causing cytotoxicity. In parallel, bakuchiol significantly inhibited the LPS-stimulated expression of iNOS, COX-2, and IL-6 in BV-2 cells. However, bakuchiol had no effect on the LPS-stimulated production and mRNA expression of TNF-α or on LPS-stimulated c-Jun NH2-terminal kinase phosphorylation. In contrast, p38 MAPK and extracellular signal-regulated kinase (ERK) phosphorylation were inhibited by bakuchiol. In vivo experiments, Bakuchiol reduced microglial activation in the hippocampus and cortex tissue of LPS-injected mice. Bakuchiol significantly suppressed LPS-injected production of TNF-α and IL-6 in serum. These results indicate that the anti-neuroinflammatory effects of bakuchiol in activated microglia are mainly regulated by the inhibition of the p38 MAPK and ERK pathways. We suggest that bakuchiol may be beneficial for various neuroinflammatory diseases.

LncRNA-1810034E14Rik reduces microglia activation in experimental ischemic stroke

Background

Activation of microglial cells plays an important role in neuroinflammation after ischemic stroke. Inhibiting the activation of microglial cells has been suggested as a potential therapeutic approach in the treatment of ischemic stroke.

Methods

Oxygen-glucose deprivation in primary microglial cells and transient middle cerebral artery occlusion (MCAO) in C57BL/6 mice were used as the in vitro and in vivo ischemic stroke models. Microarray analysis was performed to investigate the overall impact of long non-coding RNAs (lncRNAs) on the inflammation status of microglial cells. RT-qPCR was used to evaluate the lncRNA levels and mRNA levels of cytokines and microglial cell markers. ELISA was taken to measure the level of cytokines. Immunofluorescence was used to observe the activation of microglial cells. Western blotting was performed to test the p65 phosphorylation.

Results

In this study, we showed that LncRNA-1810034E14Rik was significantly decreased in LPS-treated or oxygen-glucose deprivation-induced microglial cells. Overexpression of 1810034E14Rik decreased the infarct volume and alleviated brain damage in MCAO mice. 1810034E14Rik overexpression reduced the expression of inflammatory cytokines not only in ischemic stroke mice but also in oxygen-glucose deprivation-induced microglial cells. Moreover, 1810034E14Rik overexpression could suppress the activation of microglial cells and inhibit the phosphorylation of p65.

Conclusions

LncRNA-1810034E14Rik plays an anti-inflammatory role in ischemic stroke and regulates p65 phosphorylation, making it a potential target for stroke treatment.

Electronic supplementary material

The online version of this article (10.1186/s12974-019-1464-x) contains supplementary material, which is available to authorized users.

Lentivirus-Mediated HDAC3 Inhibition Attenuates Oxidative Stress in APPswe/PS1dE9 Mice

Amyloid-β (Aβ) induces a burst of oxidative stress and plays a critical role in the pathogenesis of Alzheimer's disease (AD). Our previous results have shown that histone deacetylase 3 (HDAC3) inhibition ameliorates spatial memory deficits and decreases the Aβ burden in the brains of 9-month-old APPswe/PS1dE9 (APP/PS1) mice. In this study, we investigated the role of HDAC3 inhibition in oxidative stress in vivo and in vitro models of AD. HDAC3 was detected mainly in the neurons, and HDAC3 inhibition significantly decreased reactive oxygen species generation and improved primary cortical neuron viability. In addition, HDAC3 inhibition attenuated spatial memory dysfunction in 6-month-old APP/PS1 mice, and decreased the apoptotic rate in the hippocampi as demonstrated by TUNEL staining. HDAC3 inhibition also reduced markers of lipid peroxidation, protein oxidation, and DNA/RNA oxidation in the hippocampi of APP/PS1 mice. Moreover, HDAC3 inhibition inactivated the c-Abl/MST1/YAP signaling pathway in the hippocampi of APP/PS1 mice. In conclusion, our data show that HDAC3 inhibition can attenuate spatial memory deficits and inhibit oxidative stress in APP/PS1 mice; these results indicate a potential strategy for AD treatment.

Acorus calamus: a bio-reserve of medicinal values

Many plants are found to possess reliable pharmacological properties and have started to attract the attention of researchers. One such holistic plant is Acorus calamus, commonly known as sweet flag, belonging to the rhizomatous family Acoraceae. The different parts of this plant, such as the leaves and rhizomes, are used traditionally in different medicinal preparations for the treatment of various ailments including arthritis, neuralgia, diarrhoea, dyspepsia, kidney and liver troubles, eczema, sinusitis, asthma, fevers, bronchitis, hair loss, and other disorders. Many reports have also appeared in mainstream scientific journals confirming its nutritional and medicinal properties. Biochemical analysis of the plant has revealed a large number of secondary metabolites that may be responsible for its rich medicinal properties. Basic scientific research has uncovered the mechanisms by which itexerts its therapeutic effects. Medicinal herbs such as A. calamus are quite promising in the recent therapeutic scenario, with a large number of people favouring remedies and health approaches that are free from the side effects often associated with synthetic chemicals. In this review, we try to summarise the ethno-medicinal uses, botanical descriptions, phytochemical constituents, and biological activity of the plant parts, as well as the molecular targets of A. calamus, which we hope will serve as a good base for further work on this plant.

FasL incapacitation alleviates CD4+ T cells-induced brain injury through remodeling of microglia polarization in mouse ischemic stroke

Inflammation responses involving the crosstalk between infiltrated T cells and microglia play crucial roles in ischemia stroke. Recent studies showed that Fas ligand (FasL) mutation could reduce post-stroke T cell invasion and microglia activation. In this study, we demonstrated that CD4⁺ T cells could induce M1 microglia polarization through NF-κB signaling pathway, whereas FasL mutant CD4⁺ T cells significantly reversed this effect. Besides, Th17/Treg cells balance was skewed into Treg cells after FasL mutation. In addition, conditioned medium from co-culture of FasL mutant CD4⁺ T cells and microglia could alleviate neuronal injury. Collectively, FasL incapacitation could alleviate CD4⁺ T cells-induced inflammation through remodeling microglia polarization, suggesting a therapeutic potential for control of inflammation responses after ischemic stroke.

Long non-coding RNA PVT1 promote LPS-induced septic acute kidney injury by regulating TNFα and JNK/NF-κB pathways in HK-2 cells

This study aimed to investigate the effect and underlying mechanism of long non-coding RNA plasmacytoma variant translocation 1 (PVT1) in lipopolysaccharide (LPS)-induced inflammation injury in HK-2 cells. We established LPS-induced septic acute kidney injury (AKI) model in HK-2 cells. LPS-induced HK-2 cells were transfected with pc-PVT1, pc-NC, si-PVT1 or si-NC. Cell viability and apoptosis rate were detected by MTT assay and Annexin V-FITC/PI Apoptosis Detection kit, respectively. The relationships of PVT1 and inflammatory factors were evaluated by RNA Immunoprecipitation (RIP) assay. The levels of inflammatory factors, apoptosis-related proteins and the expressions of proteins related to c-Jun N-terminal kinase (JNK) and nuclear factor-κB (NF-κB) signaling pathway were detected by ELISA or Western blotting. Compared with cells with pc-NC, cell viability was remarkably decreased and cell apoptosis rate was increased in LPS-induced cells with pc-PVT1 (p<0.05). The levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and IL-1β were significantly increased in LPS-induced cells with pc-PVT1 compared with cells with pc-NC (p<0.05). All these changes were reversed in LPS-induced cells with si-PVT1 and si-NC (p<0.05). RTP assay revealed that PVT1 could bind to TNF-α. Furthermore, down-regulated PVT1 remarkably reduced the expressions of p-JNK and p-c-Jun, p-IκBα and p-p65 (p<0.05); while increased expressions of these proteins and inflammatory factors induced by up-regulated PVT1 were reversed by JNK or NF-κB inhibitors. PVT1 may promote inflammatory response by binding to TNF-α and inhibiting JNK/NF-κB signaling pathway in LPS-induced septic AKI cells.

Neuronal Soluble Fas Ligand Drives M1-Microglia Polarization after Cerebral Ischemia

AIMS

This study explored sFasL expression in neurons and the potential role of neuronal sFasL in modulating the microglial phenotypes.

METHODS

In vivo, middle cerebral artery occlusion (MCAO) was induced in both FasL-mutant (gld) and wild-type (wt) mice. In vitro, primary cortical neuron or microglia or coculture from wt/gld mice was subjected to oxygen glucose deprivation (OGD). sFasL level in the supernatant was evaluated by ELISA. Neuronal-conditioned medium (NCM) or exogenous sFasL was applied to primary microglia with or without FasL neutralizing antibody. Protein expression of JAK2/STAT3 and NF-κB pathways were determined by Western blot. The effect of microglia phenotype from wt/gld mice on the fate of ischemic neurons was further elucidated.

RESULTS

In vivo, compared with wild-type mice, M1 markers (CD16, CD32 and iNOS) were attenuated in gld mice after MCAO. In vitro, post-OGD neuron released more sFasL. Both post-OGD NCM and exogenous sFasL could trigger M1-microglial polarization. However, this M1 phenotype shift was partially blocked by utilization of FasL neutralizing antibody or gld NCM. Consistently, JAK2/STAT3 and NF-κB signal pathways were both activated in microglia after exogenous sFasL treatment. Compared with wild-type mice, M1-conditioned medium prepared from gld mice protected neuron against OGD injury.

CONCLUSIONS

Ischemic neurons release sFasL, which contributes to M1-microglial polarization. The underlying mechanisms may involve the activation of JAK2/STAT3 and NF-κB signaling pathways.

Anti-inflammatory effects and antioxidant activity of dihydroasparagusic acid in lipopolysaccharide-activated microglial cells

The activation of microglia and subsequent release of toxic pro-inflammatory factors are crucially associated with neurodegenerative disease, characterized by increased oxidative stress and neuroinflammation, including Alzheimer and Parkinson diseases and multiple sclerosis. Dihydroasparagusic acid is the reduced form of asparagusic acid, a sulfur-containing flavor component produced by Asparagus plants. It has two thiolic functions able to coordinate the metal ions, and a carboxylic moiety, a polar function, which may enhance excretion of the complexes. Thiol functions are also present in several biomolecules with important physiological antioxidant role as glutathione. The aim of this study is to evaluate the anti-inflammatory and antioxidant potential effect of dihydroasparagusic acid on microglial activation in an in vitro model of neuroinflammation. We have used lipopolysaccharide to induce an inflammatory response in primary rat microglial cultures. Our results suggest that dihydroasparagusic acid significantly prevented lipopolysaccharide-induced production of pro-inflammatory and neurotoxic mediators such as nitric oxide, tumor necrosis factor-α, prostaglandin E2, as well as inducible nitric oxide synthase and cyclooxygenase-2 protein expression and lipoxygenase activity in microglia cells. Moreover it effectively suppressed the level of reactive oxygen species and affected lipopolysaccharide-stimulated activation of mitogen activated protein kinase, including p38, and nuclear factor-kB pathway. These results suggest that dihydroasparagusic acid's neuroprotective properties may be due to its ability to dampen induction of microglial activation. It is a compound that can effectively inhibit inflammatory and oxidative processes that are important factors of the etiopathogenesis of neurodegenerative diseases.

Enhancement of dalesconols A and B production via upregulation of laccase activity by medium optimization and inducer supplementation in submerged fermentation of Daldinia eschscholzii

Dalesconols (dalesconols A and B) are novel polyketides with strong immunosuppressive activity produced by Daldinia eschscholzii. In this work, the effects of different media (M1, M2, and M3) on fungus growth and dalesconols biosynthesis were firstly tested and compared. Intermediates and enzyme analysis indicated that laccase had the major contribution to dalesconols biosynthesis. The key role of laccase on dalesconols biosynthesis was further experimentally confirmed, which suggested that the modified M2 was more favored for laccase and dalesconols production. Thereafter, the medium composition was optimized by RSM with a fermentation titer of 36.66 mg/L obtained. Furthermore, Ca(2+) induction was employed to up-regulate of laccase activity and further enhanced dalesconols production (76.90 mg/L), which was 308% higher than that in M2. In addition, dalesconols production reached 63.42 mg/L in scale-up experiments. This work indicated great potential of laccase as a key enzyme on regulation of dalesconols production.

Malibatol A regulates microglia M1/M2 polarization in experimental stroke in a PPARγ-dependent manner

Background

Activation of microglia plays a crucial role in immune and inflammatory processes after ischemic stroke. Microglia is reported with two opposing activated phenotypes, namely, classic phenotype (M1) and the alternative phenotype (M2). Inhibiting M1 while stimulating M2 has been suggested as a potential therapeutic approach in the treatment of stroke.

Findings

In this study, we indicated that a novel natural anti-oxidant extracted from the Chinese plant Hopea hainanensis, malibatol A (MA), decreased the infarct size and alleviated the brain injury after mice middle cerebral artery occlusion (MCAO). MA inhibited expression inflammatory cytokines in not only MCAO mice but also lipopolysaccharide (LPS)-stimulated microglia. Moreover, treatment of MA decreased M1 markers (CD16, CD32, and CD86) and increased M2 markers (CD206, YM-1) while promoting the activation of nuclear receptor PPARγ.

Conclusions

MA has anti-inflammatory effects in MCAO mice in a PPARγ-dependent manner, making it a potential candidate for stroke treatment.

Curcumenol isolated from Curcuma zedoaria suppresses Akt-mediated NF-κB activation and p38 MAPK signaling pathway in LPS-stimulated BV-2 microglial cells

Curcumenol attenuates the inflammatory responses induced by LPS in BV-2 microglial cells.

Pyrroloquinoline quinone (PQQ) inhibits lipopolysaccharide induced inflammation in part via downregulated NF-κB and p38/JNK activation in microglial and attenuates microglia activation in lipopolysaccharide treatment mice

Therapeutic strategies designed to inhibit the activation of microglia may lead to significant advancement in the treatment of most neurodegenerative diseases. Pyrroloquinoline quinone (PQQ) is a naturally occurring redox cofactor that acts as an essential nutrient, antioxidant, and has been reported to exert potent immunosuppressive effects. In the present study, the anti-inflammatory effects of PQQ was investigated in LPS treated primary microglia cells. Our observations showed that pretreatment with PQQ significantly inhibited the production of NO and PGE2 and suppressed the expression of pro-inflammatory mediators such as iNOS, COX-2, TNF-a, IL-1b, IL-6, MCP-1 and MIP-1a in LPS treated primary microglia cells. The nuclear translocation of NF-κB and the phosphorylation level of p65, p38 and JNK MAP kinase pathways were also inhibited by PQQ in LPS stimulated primary microglia cells. Further a systemic LPS treatment acute inflammation murine brain model was used to study the suppressive effects of PQQ against neuroinflammation in vivo. Mice treated with PQQ demonstrated marked attenuation of neuroinflammation based on Western blotting and immunohistochemistry analysis of Iba1-against antibody in the brain tissue. Indicated that PQQ protected primary cortical neurons against microglia-mediated neurotoxicity. These results collectively suggested that PQQ might be a promising therapeutic agent for alleviating the progress of neurodegenerative diseases associated with microglia activation.

TL-2 attenuates β-amyloid induced neuronal apoptosis through the AKT/GSK-3β/β-catenin pathway

β-amyloid (Aβ)-mediated neuronal apoptosis contributes to the progression of Alzheimer's disease (AD), although the exact mechanism remains unclear. This study aimed to investigate whether Dalesconol B (TL-2), a potent immunosuppressive agent with an unusual carbon skeleton, could inhibit Aβ-induced apoptosis in vitro and in vivo and to explore the underlying mechanisms. Aβ(1-42) was injected to bilateral hippocampus of mice to make the AD models in vivo. TL-2 was able to cross the blood-brain barrier and attenuate memory deficits in the AD mice. TL-2 also inhibited Aβ(1-42)-induced neuronal apoptosis in vitro and in vivo. In addition, TL-2 could activate the AKT/GSK-3β pathway, and inhibition of AKT and activation of GSK-3β partially eliminated the neuroprotective effects of TL-2. Furthermore, TL-2 induced the nuclear translocation of β-catenin and enhanced its transcriptional activity through the AKT/GSK-3β pathway to promote neuronal survival. These results suggest that TL-2 might be a potential drug for AD treatment.

Oridonin attenuates Aβ1-42-induced neuroinflammation and inhibits NF-κB pathway

Neuroinflammation induced by beta-amyloid (Aβ) plays a critical role in the pathogenesis of Alzheimer’s disease (AD), and inhibiting Aβ-induced neuroinflammation serves as a potential strategy for the treatment of AD. Oridonin (Ori), a compound of Rabdosia rubescens, has been shown to exert anti-inflammatory effects. In this study, we demonstrated that Ori inhibited glial activation and decreased the release of inflammatory cytokines in the hippocampus of Aβ_1–42-induced AD mice. In addition, Ori inhibited the NF-κB pathway and Aβ_1–42-induced apoptosis. Furthermore, Ori could attenuate memory deficits in Aβ_1–42-induced AD mice. In conclusion, our study demonstrated that Ori inhibited the neuroinflammation and attenuated memory deficits induced by Aβ_1–42, suggesting that Ori might be a promising candidate for AD treatment.

A novel cell line from spontaneously immortalized murine microglia

BACKGROUND

Purified microglia cultures are useful tools to study microglial behavior in vitro. Microglial cell lines serve as an attractive alternative to primary microglia culture, circumventing the costly and lengthy preparation of the latter. However, immortalization by genetic or pharmacologic manipulations may show altered physiology from primary microglia.

NEW METHOD

A novel microglial cell line was isolated from a primary glial culture of postnatal murine cerebral cortices. The culture contained a population of spontaneously transformed microglia that continued to divide without genetic or pharmacological manipulations. After several clones were isolated, one particular clone, SIM-A9, was analyzed for its microglial characteristics.

RESULTS

SIM-A9 cells expressed macrophage/microglia-specific proteins, CD68 and Iba1. SIM-A9 cells were responsive to exogenous inflammatory stimulation with lipopolysaccharide and β-amyloid, triggering tyrosine kinase-based and NFκB signaling cascades as well as TNFα secretion. SIM-A9 cells also exhibited phagocytic uptake of fluorescent labeled β-amyloid and bacterial bioparticles. Furthermore, lipopolysaccharide increased the levels of inducible nitric oxide synthase and cyclooxygenase-2, whereas IL-4 stimulation increased arginase-1 levels demonstrating that SIM-A9 cells are capable of switching their profiles to pro- or anti-inflammatory phenotypes, respectively.

COMPARISON WITH EXISTING METHODS

The use of SIM-A9 cells avoids expensive and lengthy procedures required for the preparation of primary microglia. Spontaneously immortalized SIM-A9 cells are expected to behave more comparably to primary microglia than virally transformed or pharmacologically induced microglial cell lines.

CONCLUSIONS

SIM-A9 cells exhibit key characteristics of cultured primary microglia and may serve as a valuable model system for the investigation of microglial behavior in vitro.

IMM-H004, a novel coumarin derivative compound, attenuates the production of inflammatory mediatory mediators in lipopolysaccharide-activated BV2 microglia

Therapeutic strategies designed to inhibit the activation of microglia may lead to significant advancement in the treatment of most neurodegenerative diseases. 7-hydroxy-5-methoxy-4-methyl-3-(4-methylpiperazin-1-yl)-coumarin (IMM-H004) is a novel compound and has been reported exerting potent neuroprotective effects which may be related to anti-inflammation. In the present study, the anti-inflammatory effects of IMM-H004 were investigated in lipopolysaccharide (LPS)-treated BV2 microglia. Our observations indicated that treatment with IMM-H004 significantly inhibited BV2 microglia activation, protected PC12 cells and primary neurons against indirect toxicity mediated by exposure to conditioned medium (CM) from LPS-treated BV2 cells. Additionally, IMM-H004 significantly suppressed the release of TNF-α, IL-1β and NO, and suppressed the expression of pro-inflammatory mediators and cytokines such as iNOS, COX-2, and IL-6 in LPS-stimulated BV2 microglia. The nuclear translocation of NF-κB and the phosphorylation level of JNK and p38 MAPK pathways were also inhibited by IMM-H004 in LPS-treated BV2 microglia. Moreover, IMM-H004 also was a strong selective OH scavenger whose effect was similar with vitamin C. Overall, our findings suggested that IMM-H004 might be a promising therapeutic agent for alleviating the progress of neurodegenerative diseases associated with microglia activation.

Hydroxy-safflor yellow A attenuates Aβ₁₋₄₂-induced inflammation by modulating the JAK2/STAT3/NF-κB pathway

Beta-amyloid (Aβ)-mediated inflammation plays a critical role in the initiation and progression of Alzheimer׳s disease (AD). Anti-inflammatory treatment may provide therapeutic benefits. In this study, the effect of hydroxy-safflor yellow A (HSYA) on Aβ1-42-induced inflammation in AD mice was investigated and the underlying mechanisms were explored. Aβ1-42 was injected into bilateral hippocampi of mice to induce AD models in vivo. Spatial learning and memory of mice were investigated by the Morris water maze test. Activated microglia and astrocytes were examined by immunofluorescence staining for ionized calcium-binding adapter molecule-1 (Iba-1) and glial fibrillary acidic protein (GFAP). The mRNA of inflammatory cytokines were measured using real-time PCR. NF-κB p65 translocation was analyzed by western blotting and immunostaining. IκB and phosphorylation of JAK2 and STAT3 were tested by western blotting. The results showed that HSYA ameliorated the memory deficits in Aβ1-42-induced AD mice. HSYA suppressed Aβ1-42-induced activation of microglia and astrocytes and reduced the mRNA expression of pro-inflammatory mediators. HSYA up-regulated the JAK2/STAT3 pathway and inhibits the activation of NF-κB signaling pathways. Pharmacological inhibition of STAT3 by AG490 reversed the inactivation of p65 and anti-inflammatory effects of HSYA. In conclusion, these results suggest that HSYA protects Aβ1-42-induced AD model through inhibiting inflammatory response, which may involve the JAK2/STAT3/NF-κB pathway.

Sesquiterpene dimer (DSF-52) from Artemisia argyi inhibits microglia-mediated neuroinflammation via suppression of NF-κB, JNK/p38 MAPKs and Jak2/Stat3 signaling pathways

Microglia-involved neuroinflammation is thought to promote brain damage in various neurodegenerative disorders. Therefore, novel therapeutics suppressing microglia over-activation could prove useful for neuroprotection in inflammation-mediated neurodegenerative diseases. DSF-52 is a novel sesquiterpene dimer compound isolated from medical plant Artemisia argyi by our group. In this study, we investigated whether DSF-52 inhibited the neuroinflammatory responses in lipopolysaccharide (LPS)-activated microglia. Our findings showed that DSF-52 inhibited the production of nitric oxide (NO), prostaglandin E2 (PGE2), tumor necrosis factor-α (TNF-α), as well as mRNA expression of inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX-2), interleukin-1β (IL-1β), granulocyte-macrophage colony-stimulating factor (GM-CSF) and macrophage inflammatory protein-1α (MIP-1α) in LPS-activated BV-2 microglia. Moreover, DSF-52 markedly up-regulated mRNA levels of anti-inflammatory cytokine IL-10. Mechanism study indicated that DSF-52 suppressed Akt/IκB/NF-κB inflammation pathway against LPS treatment. Also, DSF-52 down-regulated the phosphorylation levels of JNK and p38 MAPKs, but not ERK. Furthermore, DSF-52 blocked Jak2/Stat3 dependent inflammation pathway through inhibiting Jak2 and Stat3 phosphorylation, as well as Stat3 nuclear translocation. We concluded that the inhibitory ability of DSF-52 on microglia-mediated neuroinflammation may offer a novel neuroprotective modality and could be potentially useful in inflammation-mediated neurodegenerative diseases.