LPS-stimulated BV2 Microglial Cells Research Articles

The Ameliorative Effects of the Ethyl Acetate Extract of Salicornia europaea L. and Its Bioactive Candidate, Irilin B, on LPS-Induced Microglial Inflammation and MPTP-Intoxicated PD-Like Mouse Model.

Hyperactivation of microglia, the resident innate immune cells of the central nervous system, exacerbates various neurodegenerative disorders, including Parkinson's disease (PD). Parkinson's disease is generally characterized by a severe loss of dopaminergic neurons in the nigrostriatal pathway, with substantial neuroinflammation and motor deficits. This was experimentally replicated in animal models, using neurotoxins, i.e., LPS (lipopolysaccharides) and MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine). Salicornia europaea L. (SE) has been used as a dietary supplement in Korea and Europe for several years, due to its nutritional and therapeutic value. In this study, we intend to investigate the antineuroinflammatory and anti-PD-like effects of the bioactive fraction/candidate of the SE extract. Initially, we screened various fractions of SE extract using an in vitro antioxidant assay. The optimal fraction was investigated for its in vitro antineuroinflammatory potential in LPS-stimulated BV-2 microglial cells and in vivo anti-PD-like potential in MPTP-intoxicated mice. Subsequently, to identify the potential candidate responsible for the elite therapeutic potential of the optimal fraction, we conducted antioxidant activity-guided isolation and purification; the bioactive candidate was structurally characterized using nuclear magnetic resonance spectroscopy and chromatographic techniques and further investigated for its in vitro antioxidative and antineuroinflammatory potential. The results of our study indicate that SE-EA and its bioactive candidate, Irilin B, effectively alleviate the deleterious effect of microglia-mediated neuroinflammation and promote antioxidative effects. Thus, they exhibit potential as therapeutic candidates against neuroinflammatory and oxidative stress-mediated PD-like neurodegenerative complications.

Investigating anti-neuroinflammatory mechanism of orientin in lipopolysaccharide-induced BV2 microglia cells

Chronic neuroinflammation in central nervous system (CNS) can lead to neurodegenerative diseases (ND). This was due to the over-activated microglia, which releases excessive pro-inflammatory mediators. The molecular mechanisms of orientin as anti-neuroinflammatory are yet to be fully elucidated. In order to investigate the effect of orientin on LPS-stimulated BV2 microglial cells, the cells were pre-treated with orientin at maximum non-toxic dose (MNTD) (15 µM) or half MNTD (½ MNTD) (7.5 µM) for 3 hours, followed by incubation with 0.1 µg/mL of LPS for 24 hours. The LPS-stimulated cells were then subjected to three series of studies, including the determination of ROS level using 2’,7’-dichlorofluorescindiacetate (DCFH-DA) methods and the determination of mRNA of nuclear factor (NF)- кB, Signal transducer and activator of transcription 1 (STAT1), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2)and heme oxygenase-1 (HO-1) via real-time PCR (qPCR). The findings from this study demonstrated the probable mechanism of orientin in treating neuroinflammation via the downregulation of ROS level, STAT1, NF-кB, iNOS and COX-2 whilst upregulating HO-1. Validation of molecular mechanism of orientin suggested that it could be a potential therapeutic agent in treating ND.

MicroRNA-181b-5p attenuates early postoperative cognitive dysfunction by suppressing hippocampal neuroinflammation in mice

BackgroundPostoperative cognitive dysfunction (POCD) is a common complication after surgery and its occurrence is associated with increased morbidity and mortality. However, the pathophysiology of this complication remains largely unknown. Efforts to identify causes of POCD have focused on the hippocampal neuroinflammation. Recently, accumulated evidence indicates that NeurimmiRs, a subset of microRNAs (miRNAs), which modulate both neuronal and immune processes, play an important role in neuroinflammation. However, the impact of NeurimmiRs on POCD has not been investigated. We hypothesized that NeurimmiRs is involved in surgery-induced cognitive impairment in adult mice via mediating hippocampal neuroinflammation. MethodsMicroRNA(miR)-181b-5p was found to be downregulated in the hippocampi of mice with POCD using microRNA array, which was also verified in vivo in the mouse model of POCD by Quantitative real-time polymerase chain reaction (qPCR). Subsequently, the expression of miR-181b-5p was measured in lipopolysaccharide (LPS) stimulated BV-2 microglial cells and hippocampal tissues of the mice with POCD. Then, loss of function and overexpression studies were performed by transfection with miR-181b-5p mimic/ inhibitor in cultured BV-2 cell lines and intrahippocampal injection of miR-181b-5p agomir before Surgery/Anesthesia, to identify the role of miR-181b-5p in neuroinflammation and cognitive impairments. QPCR, western blot and ELISA were used to determine the expression of proinflammatory mediators. Immunofluorescence staining was applied to evaluate the activation of microglia. Furthermore, we used bioinformatics analysis and dual-luciferase assay to predict and verify the potential target of miR-181b-5p. ResultsThe results indicated that miR-181b-5p mimic could repress the mRNA and protein expression of proinflammatory mediators, including tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and monocyte chemoattractant protein (MCP)-1 in LPS-stimulated BV-2 microglial cells, while the miR-181b-5p inhibitor induced upregulation of the above-mentioned proinflammatory factors. Further bioinformatics analysis showed that miR-181b-5p was predicted to potentially target the 3′-untranslated region (UTR) of TNF-α, and binding sites of miR-181b-5p in the 3′-UTR of TNF-α were identified by dual-luciferase assay. Importantly, injecting miR-181b-5p agomir into the hippocampus of mice before surgery, ameliorated the hippocampus-dependent memory, and was accompanied by downregulation of proinflammatory factors expression and reduced microglial activation in the hippocampus of POCD mice. ConclusionsCollectively, these findings suggest that miR-181b-5p attenuates early POCD by suppressing hippocampal neuroinflammation in mice. They also highlight the importance of studying miRNAs in the context of POCD and identify miR-181b-5p as a novel potential therapeutic target for improving POCD.

Chemical Constituents and an Antineuroinflammatory Lignan, Savinin from the Roots of Acanthopanax henryi.

The phytochemical investigation on the roots of Acanthopanax henryi (Araliaceae) resulted in the discovery of twenty compounds whose chemical structures were elucidated by the analysis of 1D-, 2D-NMR, mass spectrometry data, other physicochemical properties, and a comparison of the spectral data with the literature. They were identified as (-)-sesamin (1), helioxanthin (2), savinin (3), taiwanin C (4), 6-methoxy-7-hydroxycoumarin (5), behenic acid (6), 3-O-caffeoyl-quinic acid (7), 5-O-caffeoyl-quinic acid (8), 1,3-di-O-caffeoyl-quinic acid (9), 1,4-di-O-caffeoyl-quinic acid (10), 1,5-di-O-caffeoyl-quinic acid (11), (+)-threo-(7R,8R)-guaiacylglycerol-β-coniferyl aldehyde ether (12), (+)-erythro-(7S,8R)-guaiacylglycerol-β-coniferyl aldehyde ether (13), ferulic acid (14), caffeic acid (15), stigmasterol (16), β-sitosterol (17), adenosine (18), syringin (19), and trans-coniferin (20). Among these isolates, compound 3 showed inhibitory activity against lipopolysaccharide- (LPS-) induced nitric oxide (NO) and prostaglandin E2 (PGE2) production with IC50 values of 2.22 ± 0.11 and 2.28 ± 0.23 μM, respectively. The effects of compound 3 were associated with the suppression of LPS-induced expression of the inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein. Furthermore, compound 3 negatively regulated the production of interleukin- (IL-) 1β and tumor-necrosis factor- (TNF-) α at the transcriptional level in LPS-stimulated BV2 microglial cells. These antineuroinflammatory effects of compound 3 were mediated by p38 mitogen-activated protein kinase (MAPK).

Water-Soluble Arginyl-Diosgenin Analog Attenuates Hippocampal Neurogenesis Impairment Through Blocking Microglial Activation Underlying NF-κB and JNK MAPK Signaling in Adult Mice Challenged by LPS.

Microglia-mediated neuroinflammatory responses are well known to inhibit neurogenesis in the dentate gyrus (DG) of the adult hippocampus, and growing evidence indicates that therapeutic intervention to suppress microglial activation could be an effective strategy for restoring the impaired neurogenesis and memory performance. In the present study, we investigated the effects of water-soluble arginyl-diosgenin analog (Arg-DG) on the adult hippocampal neurogenesis using a central LPS-induced inflammatory mice model, along with the fundamental mechanisms in vivo and in vitro using LPS-stimulated microglial BV2 cells. Arg-DG (0.6mg/kg) attenuates LPS-impaired neurogenesis by ameliorating the proliferation and differentiation of neural stem cells (NSCs), and prolonging their survival. The impaired neurogenesis in the hippocampal DG triggered the cognitive function, and that treatment of Arg-DG led to the recovery of cognitive decline. Arg-DG also suppressed the production of LPS-induced pro-inflammatory cytokines in hippocampal DG by blocking microglial activation. In in vitro study, Arg-DG inhibited the production of nitric oxide (NO), nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) expression, and prostaglandin D2 production (PGD2), as well as the pro-inflammatory cytokines, such as interleukin (IL)-6, IL-1β, and tumor necrosis factor alpha (TNF-α). The anti-inflammatory effect of Arg-DG was regulated by NF-κB and MAPK JNK signaling both in vivo, and in LPS-stimulated microglial BV2 cells. Taken together, these results suggest that Arg-DG might have the potential to treat various neurodegenerative disorders resulting from microglia-mediated neuroinflammation.

Anti-inflammatory pterocarpanoids from the roots of Pongamia pinnata

A phytochemical study on the roots of Pongamia pinnata afforded 11 pterocarpanoids, including three new compounds. The structures of the isolated compounds were determined by 1D and 2D NMR and HRESIMS data. The absolute configurations of the new compounds were assigned via analysis of the specific rotations and electronic circular dichroism (ECD) spectra. The isolates were evaluated for their inhibitory effects on nitric oxide (NO) production in LPS-stimulated BV-2 microglial cells. Six compounds exhibited inhibitory effects against NO production, and compound 5 showed the best activity with an IC50 value at 12.0 μM.

The NLRP3 inflammasome is involved in the neuroprotective mechanism of neural stem cells against microglia-mediated toxicity in SH-SY5Y cells via the attenuation of tau hyperphosphorylation and amyloidogenesis

The cognitive impairment caused by Alzheimer’s disease (AD) is associated with beta-amyloid (Aβ) and tau proteins, and is accompanied by inflammation. Recently, a novel inflammasome signaling pathway has been uncovered. Inflammasomes are implicated in the execution of inflammatory responses and pyroptotic death leading to neurodegeneration. Thus, the inflammasome signaling pathway could be a potential therapeutic target for AD. Neural stem cells (NSCs) are multipotent cells that can self-renew and differentiate into distinct neural cells. NSC therapy has been considered to be a promising therapeutic approach in protecting the central nervous system and restoring it following damage. However, the mechanisms involved remain unclear. The aims of this study were to investigate the protective effects of NE4C neural stem cells against microglia-mediated neurotoxicity and to explore molecular mechanisms mediating their actions. NE4C decreased the levels of caspase-1 and IL-1β, and attenuated the level of the NLRP3 inflammasome and its associated protein adapter, apoptosis-associated speck-like protein containing a C-terminal caspase recruitment domain (ASC) in LPS-stimulated BV2 microglial cells, possibly by regulating the phosphorylation of p38α MAPK. The conditioned media obtained from co-culture of LPS-stimulated BV2 and NE4C cells exhibited protective effects on SH-SY5Y cells against microglia-mediated neurotoxicity; this was associated with an attenuation of tau phosphorylation and amyloidogenesis and accompanied by down-regulation of GSK-3β and p38α MAPK signalling pathways. In conclusion, the present study suggested that NSC therapy could be a potential strategy against microglia-mediated neurotoxicity. NSCs regulate NLRP3 activation and IL-1β secretion, which are critical in the initiation of the inflammatory responses, hence preventing the release of neurotoxic pro-inflammatory factors by microglia. This eventually reduces tau hyperphosphylation and amyloidogenesis, possibly through the regulation of GSK-3β and p38α MAPK signalling pathways, and thus protects SH-SY5Y cells against microglia-mediated neurotoxicity.

Anti-inflammatory effects of isoalantolactone on LPS-stimulated BV2 microglia cells through activating GSK-3β-Nrf2 signaling pathway

Isoalantolactone (ISO) is a sesquiterpene lactone isolated from Inula helenium that has been known to exhibit anti-inflammatory effect. Nevertheless, the effects of ISO on neuroinflammation have not been explored. BV2 microglia cells were pretreated with ISO and then stimulated with LPS. ISO attenuated the production of inflammatory mediators, such as TNF-α, IL-1β, NO, and PGE2 in LPS-stimulated BV2 microglia cells. ISO suppressed the LPS-induced NF-κB activation in a concentration-dependent manner. The expression of Nrf2 and HO-1 were increased by the treatment of ISO. Inhibition of Nrf2 by siRNA could reverse the anti-inflammatory effects of ISO, as confirmed by the reversed inflammatory mediator production. Furthermore, ISO increased the level of phosphorylated GSK-3β, the upstream molecule of Nrf2. In conclusion, these results indicated that ISO might exhibit its anti-inflammatory effects through activating GSK-3β-Nrf2 signaling pathway.

Two new chromene derivatives from Artemisia songarica

Two new chromene derivatives, songaricachromenes A (1) and B (2), were isolated from Artemisia songarica, along with 10 known compounds (3–12). The structures and stereochemistry of the new compounds were elucidated by analyses of the NMR, MS, and electronic circular dichroism (ECD) data. All the isolates (1–12) were evaluated for their NO inhibitory effects on LPS-stimulated BV-2 microglial cells.

Isolation of Novel Sesquiterpeniods and Anti-neuroinflammatory Metabolites from Nardostachys jatamansi.

Nardostachys jatamansi contains various types of sesquiterpenoids that may play an important role in the potency of plant’s anti-inflammatory effects, depending on their structure. In this study, five new sesquiterpenoids, namely kanshone L (1), kanshone M (2), 7-methoxydesoxo-narchinol (3), kanshone N (4), and nardosdaucanol (5), were isolated along with four known terpenoids (kanshone D (6), nardosinanone G (7), narchinol A (8), and nardoaristolone B (9)) from the rhizomes and roots of Nardostachys jatamansi. Their structures were determined by analyzing 1D and 2D NMR and MS data. Among the nine sesquiterpenoids, compounds 3, 4, and 8 were shown to possess dose-dependent inhibitory effects against lipopolysaccharide (LPS)-stimulated nitric oxide (NO) production in BV2 microglial cells. Furthermore, compounds 3, 4, and 8 exhibited anti-neuroinflammatory effects by inhibiting the production of pro-inflammatory mediators, including prostaglandin E2 (PGE2), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) proteins, as well as pro-inflammatory cytokines, such as interleukin (IL)-1β, IL-12 and tumor necrosis factor-α (TNF-α), in LPS-stimulated BV2 microglial cells. Moreover, these compounds were shown to inhibit the activation of the NF-κB signaling pathway in LPS-stimulated BV2 microglial cells by suppressing the phosphorylation of IκB-α and blocking NF-κB translocation. In conclusion, five new and four known sesquiterpenoids were isolated from Nardostachys jatamansi, and compounds 3, 4, and 8 exhibited anti-neuroinflammatory effects in LPS-stimulated BV2 microglial cells through inhibiting of NF-κB signaling pathway.

Upregulation of Suppressor of Cytokine Signaling 3 in Microglia by Cinnamic Acid.

Neuroinflammation plays an important role in the pathogenesis of various neurodegenerative diseases including Alzheimer's disease (AD). Suppressor of cytokine signaling 3 (SOCS3) is an anti-inflammatory molecule that suppresses cytokine signaling and inflammatory gene expression in different cells including microglia. The pathways through which SOCS3 could be upregulated are poorly described. Cinnamic acid is a metabolite of cinnamon, a natural compound that is being widely used all over the world as a spice or flavoring agent. Here, we examined if cinnamic acid could upregulate SOCS3 in microglia. Microglia and astroglia isolated from mouse brain as well as BV-2 microglial cells were treated with cinnamic acid followed by monitoring the level of SOCS3 and different proinflammatory molecules by RT-PCR and real-time PCR. To nail down the mechanism, we also performed ChIP analysis to monitore the recruitment of cAMP response element binding (CREB) to the socs3 gene promoter and carried out siRNA knockdown of CREB. Cinnamic acid upregulated the expression of SOCS3 mRNA and protein in mouse BV-2 microglial cells in dose- and time-dependent manner. Accordingly, cinnamic acid also increased the level of SOCS3 and suppressed the expression of inducible nitric oxide synthase and proinflammatory cytokines (TNFα, IL-1β and IL-6) in LPSstimulated BV-2 microglial cells. Similar to BV-2 microglial cells, cinnamic acid also increased the expression of SOCS3 in primary mouse microglia and astrocytes. We have seen that cAMP response element is present in the promoter of socs3 gene, that cinnamic acid induces the activation of CREB, that siRNA knockdown of CREB abrogates cinnamic acid-mediated upregulation of SOCS3, and that cinnamic acid treatment leads to the recruitment of CREB to the socs3 gene. These studies suggest that cinnamic acid upregulates the expression of SOCS3 in glial cells via CREB pathway, which may be of importance in neuroinflammatory and neurodegenerative disorders.

Lactobacillus johnsonii CJLJ103 Attenuates Scopolamine-Induced Memory Impairment in Mice by Increasing BDNF Expression and Inhibiting NF-��B Activation

In the present study, we examined whether Lactobacillus johnsonii CJLJ103 (LJ) could alleviate cholinergic memory impairment in mice. Oral administration of LJ alleviated scopolamine-induced memory impairment in passive avoidance and Y-maze tasks. Furthermore, LJ treatment increased scopolamine-suppressed BDNF expression and CREB phosphorylation in the hippocampi of the brain, as well as suppressed TNF-α expression and NF-κB activation. LJ also increased BDNF expression in corticosterone-stimulated SH-SY5Y cells and inhibited NF-κB activation in LPS-stimulated microglial BV2 cells. However, LJ did not inhibit acetylcholinesterase activity. These findings suggest that LJ, a member of human gut microbiota, may mitigate cholinergic memory impairment by increasing BDNF expression and inhibiting NF-κB activation.

Anti-neuroinflammatory effects of galangin in LPS-stimulated BV-2 microglia through regulation of IL-1β production and the NF-κB signaling pathways.

Neuroinflammation resulting from microglial activation is involved in the pathogenesis of neurodegenerative diseases, including Parkinson's diseases. Microglial activation plays an important role in neuroinflammation and contributes to several neurological disorders. Hence, inhibition of both microglial activation and the generation of pro-inflammatory cytokines may lead to an effective treatment for neurodegenerative diseases. In the present study, the anti-neuroinflammatory effects of galangin were investigated in lipopolysaccharide (LPS)-stimulated BV-2 microglial cells. Galangin significantly decreased the generation of nitric oxide, interleukin-1β, and inducible nitric oxide synthase in LPS-stimulated BV-2 microglial cells. In addition, galangin inhibited the phosphorylation of p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase 1/2. Furthermore, it was observed that activation of both IκB-α and nuclear factor kappa B (NF-κB) was significantly increased following LPS stimulation, and this effect was suppressed by galangin treatment. In conclusion, galangin displayed an anti-neuroinflammatory activity in LPS-stimulated BV-2 microglial cells. Galangin inhibited LPS-induced neuroinflammation via the MAPK and NF-κB signaling pathways and might act as a natural therapeutic agent for the treatment of various neuroinflammatory conditions.

Anti-inflammatory and antioxidant mechanisms of urolithin B in activated microglia

BackgroundUrolithin B is one of the gut microbial metabolites of ellagitannins and is found in diverse plant foods, including pomegranates, berries, walnuts, tropical fruits, and medicinal herbs. Although a number of biological activities of urolithin B have been reported, the anti-inflammatory and antioxidant effects of urolithin B in neuroinflammation have not been clearly demonstrated. PurposeThe present study aimed to investigate the anti-inflammatory and antioxidant effects of urolithin B in activated microglia and define its underlying molecular mechanisms. Study designThe effects of urolithin B on the expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and cytokines were examined in BV2 microglial cells using enzyme-linked immunosorbent assay (ELISA), reverse transcription polymerase chain reaction (RT-PCR), and Western blot analysis. Microglial activation in the lipopolysaccharide (LPS)-injected mouse brain was assessed using immunohistochemistry. The detailed molecular mechanisms underlying the anti-inflammatory and antioxidant effects of urolithin B were analyzed using an electrophoretic mobility shift assay, reporter gene assay, Western blot, and RT-PCR. ResultsUrolithin B inhibited the production of NO and pro-inflammatory cytokines, while increased anti-inflammatory cytokine IL-10 in LPS-stimulated BV2 microglial cells. In addition, urolithin B inhibited NO, TNF-α, and IL-6 production in lipoteichoic acid (LTA) or polyinosinic-polycytidylic acid (poly(I:C))-stimulated BV2 cells, suggesting that the anti-inflammatory effect of urolithin B is not confined to LPS stimulation. Urolithin B also showed an antioxidant effect by reducing intracellular reactive oxygen species (ROS) production and NADPH oxidase subunit expression, and by upregulating the antioxidant hemeoxygenase-1 expression via Nrf2/ARE signaling. More detailed mechanistic studies showed that urolithin B inhibited NF-κB activity by reducing the phosphorylation and degradation of IκBα. In addition, urolithin B suppressed the phosphorylation of JNK, ERK, and Akt, and enhanced the phosphorylation of AMPK, which is associated with anti-inflammatory and antioxidant processes. Finally, we demonstrated that urolithin B suppressed microglia activation in LPS-injected mouse brains. ConclusionsThe strong anti-inflammatory and antioxidant effects of urolithin B may provide therapeutic potential for neuroinflammatory disorders that are associated with oxidative stress and microglial activation.

Two new phenylpropanoids from Amomum paratsao-ko S. Q. Tong et Y. M. Xia

Two new phenylpropanoids, trans-(decyl-2-ene)-3-(4-hydroxy-3-methoxy-phenyl)propenoate (1) and trans-10-hydroxydecyl-3-(4-hydroxyphenyl) propenoate (2) were isolated from Amomum paratsao-ko S. Q. Tong et Y. M. Xia. Their structures were elucidated by extensive spectroscopic methods including 1D and 2D NMR and MS spectra. The new compounds were both evaluated for their anti-inflammatory activities via examination of the effect on IL-6 and MCP-1 in LPS-stimulated BV2 microglial cells. Both compounds 1 and 2 upregulate MCP-1 expression, and compound 1 significantly reduces IL-6 expression. These results indicate that compound 1 has the potential for development as an anti-inflammatory agent.

A synthetic diosgenin primary amine derivative attenuates LPS-stimulated inflammation via inhibition of NF-κB and JNK MAPK signaling in microglial BV2 cells

Diosgenin, a precursor of steroid hormones in plants, is known to exhibit diverse pharmacological activities including anti-inflammatory properties. In this study, (3β, 25R)‑spirost‑5‑en‑3‑oxyl (2‑((2((2‑aminoethyl)amino)ethyl)amino)ethyl) carbamate (DGP), a new synthetic diosgenin derivative incorporating primary amine was used to investigate its anti-inflammatory effects and underlying mechanisms of action in lipopolysaccharide (LPS)-stimulated microglial BV2 cells. Pretreatment with DGP resulted in significant inhibition of nitric oxide (NO) synthesis, and down-regulation of nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in LPS-stimulated microglial BV2 cells. In addition, DGP decreased the production of reactive oxygen species (ROS) and pro-inflammatory cytokines such as interleukin (IL)-6, IL-1β, and tumor necrosis factor alpha (TNF-α). The inhibitory effects of DGP on these inflammatory mediators in LPS-stimulated microglial BV2 cells were regulated by NF-κB signaling through blocking p65 nuclear translocation and NF-κB p65/DNA binding activity. DGP also blocked the phosphorylation of c-Jun amino-terminal kinase (JNK), but not p38 kinase or extracellular signal-regulated kinases (ERK). The NF-κB inhibitor JSH-23 and JNK-specific inhibitor SP600125 significantly decreased NO production and IL-6 release in LPS-stimulated BV2 cells, respectively. The overall results demonstrate that DGP has anti-inflammatory effects on LPS-stimulated BV2 cells via inhibition of NF-κB and JNK activation, suggesting that DGP is a potential prophylactic agent in various neurodegenerative disorders.

YY1 promotes IL-6 expression in LPS-stimulated BV2 microglial cells by interacting with p65 to promote transcriptional activation of IL-6

Neuroinflammation plays a critical role in the process of neurodegenerative disorders, during which microglia, the principal resident immune cells in the central nervous system, are activated and produce proinflammatory mediators. Yin-Yang 1 (YY1), a multi-functional transcription factor, is widely expressed in cells of the immune system and participate in various cellular processes. However, whether YY1 is involved in the process of neuroinflammation is still unknown. In the present study, we found that YY1 was progressively up-regulated in BV2 microglial cells stimulated with lipopolysaccharide (LPS), which was dependent on the transactivation function of nuclear factor kappa B (NF-κB). Furthermore, YY1 knockdown notably inhibited LPS-induced the activation of NF-κB signaling and interleukin-6 (IL-6) expression in BV-2 cells, but not mitogen-activated protein kinase (MAPK) signaling. Moreover, YY1 strengthened p65 binding to IL-6 promoter by interacting with p65 but decreased H3K27ac modification on IL-6 promoter, eventually increasing IL-6 transcription. Taken together, these results for the first time uncover the regulatory mechanism of YY1 on IL-6 expression during neuroinflammation responses and provide new lights into neuroinflammation.

Anti-inflammatory Activity of 8-Hydroxydaidzein in LPS-Stimulated BV2 Microglial Cells via Activation of Nrf2-Antioxidant and Attenuation of Akt/NF-κB-Inflammatory Signaling Pathways, as Well As Inhibition of COX-2 Activity.

It was demonstrated that isoflavones can cross the blood-brain barrier, making them desirable candidate agents for the prevention of neurological symptoms. 8-Hydroxydaidzein (8-OHD, 4',7,8-trihydoxyisoflavone) is an isoflavone found only in fermented soy food. Current results showed that 8-OHD inhibited LPS-stimulated production of nitric oxide (NO) and proinflammatory cytokines, such as tumor necrosis factor (TNF)-α and interleukin (IL)-6, by inhibiting gene expression in BV2 microglial cells. Moreover, 8-OHD markedly quenched reactive oxygen species (ROS) and activated NF-E2-related factor 2 (Nrf2) so as to upregulate expression of Phase II enzymes, including heme oxygenase (HO)-1, NAD(P)H quinone dehydrogenase 1 (NQO1), and the modifier subunit of glutamate cysteine ligase (GCLM). 8-OHD also suppressed LPS-stimulated phosphorylation of Akt and NF-κB-p65. The anti-inflammatory activity of 8-OHD was attenuated by the HO-1 inhibitor zinc protoporphyrin (Znpp) but augmented by the PI3K/Akt inhibitor LY294002. 8-OHD also diminished LPS-induced prostaglandin E2 (PGE2) production without affecting cyclooxygenase (COX)-2 expression. In vitro assay shows that 8-OHD displayed mixed-type inhibition of COX-2 with an IC50 of 8.9 ± 1.2 μM. These data suggest that the anti-inflammatory activity of 8-OHD may be associated with the activation of Nrf2/HO-1 and attenuation of Akt/NF-κB signaling pathways as well as inhibition of COX-2 enzyme activity. In conclusion, 8-OHD, a potent Nrf2 activator, Akt/NF-κB activation suppressor, and COX-2 enzyme inhibitor, may have health-promoting effects for mitigating microglia activation and preventing neuroinflammation.

Theissenolactone C Exhibited Ocular Protection of Endotoxin-Induced Uveitis by Attenuating Ocular Inflammatory Responses and Glial Activation.

The aim of this study was to investigate the effects of a natural component, theissenolactone C (LC53), on the ocular inflammation of experimental endotoxin-induced uveitis (EIU) and its related mechanisms in microglia. Evaluation of the severity of anterior uveitis indicated that LC53 treatment significantly decreased iridal hyperemia and restored the clinical scores. Additionally, the deficient retina functions of electroretinography were improved by LC53. LC53 significantly reduced levels of tumor necrosis factor (TNF)-α, monocyte chemoattractant protein-1, protein leakage and activation of matrix metalloproteinases in the anterior section during EIU. Moreover, LC53 treatment decreased the oxidative stress as well as neuroinflammatory reactivities of GFAP and Iba-1 in the posterior section. Furthermore, LC53 decreased the phosphorylation of p65, expression of HSP90, Bax, and cleaved-caspase-3 in EIU. According to the microglia studies, LC53 significantly abrogated the productions of TNF-α, PGE2, NO and ROS, as well as inducible NO synthase and cyclooxygenase-2 expression in LPS-stimulated microglial BV2 cells. The microglial activation of IKKβ, p65 phosphorylation and nuclear phosphorylated p65 translocation were strongly attenuated by LC53. On the other hand, LC53 exhibited the inhibitory effects on JNK and ERK MAPKs activation. Our findings indicated that LC53 exerted the ocular-protective effect through its inhibition on neuroinflammation, glial activation, and apoptosis in EIU, suggesting a therapeutic potential with down-regulation of the NF-κB signaling for uveitis and retinal inflammatory diseases.

Taraxasterol Inhibits LPS-Induced Inflammatory Response in BV2 Microglia Cells by Activating LXRα.

Neuroinflammation plays a critical role in the development of neurodegenerative diseases. Taraxasterol, a pentacyclic-triterpene isolated from Taraxacum officinale, has been reported to have anti-inflammatory effect. The aim of this study was to investigate the anti-inflammatory effects and mechanism of taraxasterol in LPS-stimulated BV2 microglia cells. BV2 microglia cells were treated with taraxasterol 12 h before LPS stimulation. The effects of taraxasterol on LPS-induced TNF-α and IL-1β production were detected by ELISA. The effects of taraxasterol on LXRα, ABCA1, TLR4, and NF-κB expression were detected by western blot analysis. The results showed that taraxasterol dose-dependently inhibited LPS-induced TNF-α and IL-1β production and NF-κB activation. Taraxasterol also disrupted the formation of lipid rafts and inhibited translocation of TLR4 into lipid rafts. Furthermore, taraxasterol was found to activate LXRα-ABCA1 signaling pathway which induces cholesterol efflux from cells. In addition, our results showed that the anti-inflammatory effect of taraxasterol was attenuated by transfection with LXRα siRNA. In conclusion, these results suggested that taraxasterol inhibits LPS-induced inflammatory response in BV2 microglia cells by activating LXRα-ABCA1 signaling pathway.