Anti-inflammatory effects of a fluorovinyloxyacetamide compound KT-15087 in microglia cells

Caffeic acid methyl ester inhibits mast cell activation through the suppresion of MAPKs and NF-κB signaling in RBL-2H3 cells

Anti-inflammatory effects of caffeic acid derivatives have been widely reported. However, the effect of caffeic acid methyl ester (CAME) on the anti-allergic effect in mast cells has not been elucidated. The present study was aimed to investigate the anti-allergic properties of CAME and its underlying mechanism. Rat basophilic leukemia (RBL-2H3) cells were incubated withphorbol-12-myristate-13-acetate (PMA) and a calcium ionophore, A23187 to induce mast cell activation. Anti-allergic effect of CAME was examined by measuring cytokine, histamine and β-hexosaminidase release. Western blotting was conducted to determine cyclooxygenase-2 (COX-2) expression, Mitogen-activated protein kinases (MAPKs) activation and nuclear factor-κB (NF-κB) translocation. CAME significantly suppressed PMA/A23187-induced TNF-α secretion, and β-hexosaminidase and histamine release in a concentration-dependent manner. Furthermore, CAME significantly attenuated PMA/A23187-induced COX-2 expression and nuclear translocation of NF-κB. CAME significantly suppressed PMA/A23187-induced increased phosphorylation of p38, ERK and JNK RBL-2H3 cells. The results demonstrate that CAME significantly attenuates anti-allergic action by suppressing degranulation of mast cells through the suppression of MAPKs/NF-κB signaling pathway in RBL-2H3 cells.

Microglia mediated neuroinflammation - signaling regulation and therapeutic considerations with special reference to some natural compounds

Neuroinflammation plays a central role in multiple neurodegenerative diseases and neurological disorders such as Alzheimer's disease (AD), Parkinson's disease (PD), cerebral ischemic injury etc. In this connection, microglia, the key players in the central nervous system, mediate the inflammatory response process. In brain injuries, activated microglia can clear the cellular debris and invading pathogens and release neurotrophic factors; however, prolonged microglia activation may cause neuronal death through excessive release of inflammatory mediators. Therefore, it is of paramount importance to understand the underlying molecular mechanisms of microglia activation to design an effective therapeutic strategy to alleviate neuronal injury. Recent studies have shown that some natural compounds and herbal extracts possess anti-inflammatory properties that may suppress microglial activation and ameliorate neuroinflammation and hence are neuroprotective. In this review, we will update some of the common signaling pathways that regulate microglia activation. Among the various signaling pathways, the Notch-1, mitogen-activated protein kinases (MAPKs), and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) have been reported to exacerbate microglia mediated neuroinflammation that is implicated in different neuropathological diseases. The search for natural compounds or agents, specifically those derived from natural herbal extracts such as Gastrodin, scutellarin, RG1 etc. has been the focus of many of our recent studies because they have been found to regulate microglia activation. The pharmacological effects of these agents and their potential mechanisms for regulating microglia activation are systematically reviewed here for a fuller understanding of their biochemical action and therapeutic potential for treatment of microglia mediated neuropathological diseases.

3,4,5-Trihydroxycinnamic Acid Inhibits LPS-Induced Inflammatory Response by Increasing SIRT1 Expression in Human Umbilical Vein Endothelial Cells

3,4,5-Trihydroxycinnamic acid (THC) has been demonstrated to exert anti-inflammatory activities in LPS-induced RAW264.7 murine macrophage cells and in LPS-induced septic mice. However, the effect of THC on the inflammatory response in vascular endothelial cells has not been clearly examined. The goal of the present study was to elucidate the anti-inflammatory properties of THC and its underlying mechanism in LPS-challenged human umbilical vein endothelial cells (HUVECs). THC significantly suppressed LPS-induced interleukin-1β production and intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 expression and significantly decreased LPS-induced nuclear factor-κB activation by attenuating p65 phosphorylation and inhibitor of kappa B degradation. To understand the underlying mechanism of the anti-inflammatory effect of THC, the involvement of the sirtuin 1 (SIRT1) signaling pathway was examined. THC resulted in increased expression of SIRT1 in LPS-challenged HUVECs. Among the downstream molecular targets of SIRT1, the level of LPS-induced acetylated p53 was significantly decreased by THC treatment, whereas no noticeable change was observed in the levels of forkhead box O3 and peroxisome proliferator activated receptor gamma coactivator 1 alpha. In conclusion, the results clearly demonstrate that THC possesses anti-inflammatory properties by increasing SIRT1 expression and subsequent suppression of p53 activation in LPS-challenged HUVECs.

Isorhamnetin-3-O-Glucuronide Suppresses JNK and p38 Activation and Increases Heme-Oxygenase-1 in Lipopolysaccharide-Challenged RAW264.7 Cells

Preclinical Research Isorhanmetin (ISH) exhibits a wide range of biological properties including anticancer, anti-oxidant and anti-inflammatory activities. However, the pharmacological properties of isorhamnetin-3-O-glucuronide (IG), a glycoside derivative of ISH, have not been extensively examined. The objective of this study was to examine the anti-inflammatory properties of IG and its underlying mechanism in lipopolysaccharide (LPS)-challenged RAW264.7 macrophage cells in comparison with its aglycone, ISH. IG suppressed LPS-induced extracellular secretion of the proinflammatory mediators, nitric oxide (NO) and PGE2 , and proinflammatory protein expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2. IG also increased expression of heme oxygenase-1 (HO-1). IG attenuated LPS-induced activation of c-Jun N-terminal kinase (JNK) and p38 in a concentration-dependent manner with negligible suppression of extracellular signal-regulated kinases (ERK) phosphorylation. In conclusion, this study demonstrates that IG exerts anti-inflammatory activity by increasing HO-1 expression and by suppressing JNK and p38 signaling pathways in LPS-challenged RAW264.7 macrophage cells. Drug Dev Res 77 : 143-151, 2016. © 2016 Wiley Periodicals, Inc.

Quercetin-3-O-β-D-Glucuronide Suppresses Lipopolysaccharide-Induced JNK and ERK Phosphorylation in LPS-Challenged RAW264.7 Cells

Quercetin, a flavonol, has been reported to exhibit a wide range of biological properties including anti-oxidant and anti-inflammatory activities. However, pharmacological properties of quercetin-3-O-β-D-glucuronide (QG), a glycoside derivative of quercetin, have not been extensively examined. The objective of this study is to elucidate the anti-inflammatory property and underlying mechanism of QG in lipopolysaccharide (LPS)-challenged RAW264.7 macrophage cells in comparison with quercetin. QG significantly suppressed LPS-induced extracellular secretion of pro-inflammatory mediators such as nitric oxide (NO) and PGE₂, and pro-inflammatory protein expressions of iNOS and COX-2. To elucidate the underlying mechanism of the anti-inflammatory property of QG, involvement of MAPK signaling pathways was examined. QG significantly attenuated LPS-induced activation of JNK and ERK in concentration-dependent manners with a negligible effect on p38. In conclusion, the present study demonstrates QG exerts anti-inflammatory activity through the suppression of JNK and ERK signaling pathways in LPS-challenged RAW264.7 macrophage cells.

Anti-inflammatory effects of glaucocalyxin B in microglia cells

Over-activated microglia is involved in various kinds of neurodegenerative process including Parkinson, Alzheimer and HIV dementia. Suppression of microglial over activation has emerged as a novel strategy for treatment of neuroinflammation-based neurodegeneration. In the current study, anti-inflammatory and neuroprotective effects of the ent-kauranoid diterpenoids, which were isolated from the aerial parts of Rabdosia japonica (Burm. f.) var. glaucocalyx (Maxim.) Hara, were investigated in cultured microglia cells. Glaucocalyxin B (GLB), one of five ent-kauranoid diterpenoids, significantly decreased the generation of nitric oxide (NO), tumor necrosis factor (TNF)-α, interleukin (IL)-1β, cyclooxygenase (COX)-2 and inducible nitric oxide synthase (iNOS) in the lipopolysaccharide (LPS)-activated microglia cells. In addition, GLB inhibited activation of nuclear factor-κB (NF-κB), p38 mitogen-activated protein kinase (MAPK) and generation of reactive oxygen species (ROS) in LPS-activated microglia cells. Furthermore, GLB strongly induced the expression of heme oxygenase (HO)-1 in BV-2 microglia cells. Finally, GLB exhibited neuroprotective effect by preventing over-activated microglia induced neurotoxicity in a microglia/neuron co-culture model. Taken together, the present study demonstrated that the GLB possesses anti-nueroinflammatory activity, and might serve as a potential therapeutic agent for treating neuroinflammatory diseases.

Lonicera japonica THUNB. Extract Inhibits Lipopolysaccharide-Stimulated Inflammatory Responses by Suppressing NF-κB Signaling in BV-2 Microglial Cells

In the current study, we evaluated the anti-inflammatory effects of Lonicera japonica THUNB. (LJ) and its underlying molecular mechanism in lipopolysaccharide (LPS)-stimulated BV-2 microglial cells. Our results indicated that LJ significantly inhibits LPS-stimulated production of nitric oxide (NO) and prostaglandin E2 (PGE2). In addition, LJ inhibited inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) at both the protein and mRNA levels. In LPS-stimulated BV-2 microglial cells, LJ inhibited proinflammatory cytokines and chemokines, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), monocyte chemoattractant protein-1 (MCP-1), matrix metalloproteinase-9 (MMP-9) enzymatic activities, and/or mRNA expression, as well as reactive oxygen species (ROS) production. LJ significantly suppressed activation of nuclear factor-κB (NF-κB) and its translocation from the cytosol to the nucleus and suppressed the DNA-binding activity of NF-κB. Furthermore, LJ significantly inhibited phosphorylation of c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase 1/2 (ERK 1/2), p38 mitogen-activated protein kinases (MAPKs), phosphatidylinositol 3-kinases (PI3K)/Akt, and Janus kinase 1 (JAK1)/signal transducer and activator of transcription (STAT)1/3. Collectively, our findings indicated that the antineuroinflammatory properties of LJ in LPS-induced BV-2 microglial cells is due to downregulation of proinflammatory cytokines and chemokines downstream of inhibition of NF-κB activation.

Immunostimulating activity of maysin isolated from corn silk in murine RAW 264.7 macrophages

Corn silk (CS) has long been consumed as a traditional herb in Korea. Maysin is a major flavonoid of CS. The effects of maysin on macrophage activation were evaluated, using the murine macrophage RAW 264.7 cells. Maysin was isolated from CS by methanol extraction, and preparative C₁₈ reverse phase column chromatography. Maysin was nontoxic up to 100 μg/ml, and dose-dependently increased TNF-α secretion and iNOS production by 11.2- and 4.2-fold, respectively, compared to untreated control. The activation and subsequent nuclear translocation of NF-κB was substantially enhanced upon treatment with maysin (1-100 μg/ml). Maysin also stimulated the phosphorylation of Akt and MAPKs (ERK, JNK). These results indicated that maysin activates macrophages to secrete TNF-α and induce iNOS expression, via the activation of the Akt, NF-κB and MAPKs signaling pathways. These results suggest for the first time that maysin can be a new immunomodulator, enhancing the early innate immunity. [BMB Reports 2014; 47(7): 382-387]

N-(p-Coumaryol)-Tryptamine Suppresses the Activation of JNK/c-Jun Signaling Pathway in LPS-Challenged RAW264.7 Cells

N-(p-Coumaryol) tryptamine (CT), a phenolic amide, has been reported to exhibit anti-oxidant and anti-inflammatory activities. However, the underlying mechanism by which CT exerts its pharmacological properties has not been clearly demonstrated. The objective of this study is to elucidate the anti-inflammatory mechanism of CT in lipopolysaccharide (LPS)-challenged RAW264.7 macrophage cells. CT significantly inhibited LPS-induced extracellular secretion of pro-inflammatory mediators such as nitric oxide (NO) and PGE2, and protein expressions of iNOS and COX-2. In addition, CT significantly suppressed LPS-induced secretion of pro-inflammatory cytokines such as TNF-α and IL-1β. To elucidate the underlying anti-inflammatory mechanism of CT, involvement of MAPK and Akt signaling pathways was examined. CT significantly attenuated LPS-induced activation of JNK/c-Jun, but not ERK and p38, in a concentration-dependent manner. Interestingly, CT appeared to suppress LPS-induced Akt phosphorylation. However, JNK inhibition, but not Akt inhibition, resulted in the suppression of LPS-induced responses, suggesting that JNK/c-Jun signaling pathway significantly contributes to LPS-induced inflammatory responses and that LPS-induced Akt phosphorylation might be a compensatory response to a stress condition. Taken together, the present study clearly demonstrates CT exerts anti-inflammatory activity through the suppression of JNK/c-Jun signaling pathway in LPS-challenged RAW264.7 macrophage cells.

Methyl p-Hydroxycinnamate Suppresses Lipopolysaccharide-Induced Inflammatory Responses through Akt Phosphorylation in RAW264.7 Cells

Derivatives of caffeic acid have been reported to possess diverse pharmacological properties such as anti-inflammatory, anti-tumor, and neuroprotective effects. However, the biological activity of methyl p-hydroxycinnamate, an ester derivative of caffeic acid, has not been clearly demonstrated. This study aimed to elucidate the anti-inflammatory mechanism of methyl p-hydroxycinnamate in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells. Methyl p-hydroxycinnamate significantly inhibited LPS-induced excessive production of pro-inflammatory mediators such as nitric oxide (NO) and PGE₂ and the protein expression of iNOS and COX-2. Methyl p-hydroxycinnamate also suppressed LPS-induced overproduction of pro-inflammatory cytokines such as IL-1β and TNF-α. In addition, methyl p-hydroxycinnamate significantly suppressed LPS-induced degradation of IκB, which retains NF-κB in the cytoplasm, consequently inhibiting the transcription of pro-inflammatory genes by NF-κB in the nucleus. Methyl p-hydroxycinnamate exhibited significantly increased Akt phosphorylation in a concentration-dependent manner. Furthermore, inhibition of Akt signaling pathway with wortmaninn abolished methyl p-hydroxycinnamate-induced Akt phosphorylation. Taken together, the present study clearly demonstrates that methyl p-hydroxycinnamate exhibits anti-inflammatory activity through the activation of Akt signaling pathway in LPS-stimulated RAW264.7 macrophage cells.

Phosphorylation of Akt Mediates Anti-Inflammatory Activity of 1-p-Coumaroyl β-D-Glucoside Against Lipopolysaccharide-Induced Inflammation in RAW264.7 Cells

Hydroxycinnamic acids have been reported to possess numerous pharmacological activities such as antioxidant, anti-inflammatory, and anti-tumor properties. However, the biological activity of 1-p-coumaroyl β-D-glucoside (CG), a glucose ester derivative of p-coumaric acid, has not been clearly examined. The objective of this study is to elucidate the anti-inflammatory action of CG in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophage cells. In the present study, CG significantly suppressed LPS-induced excessive production of pro-inflammatory mediators such as nitric oxide (NO) and PGE2 and the protein expression of iNOS and COX-2. CG also inhibited LPS-induced secretion of pro-inflammatory cytokines, IL-1β and TNF-α. In addition, CG significantly suppressed LPS-induced degradation of IκB. To elucidate the underlying mechanism by which CG exerts its anti-inflammatory action, involvement of various signaling pathways were examined. CG exhibited significantly increased Akt phosphorylation in a concentration-dependent manner, although MAPKs such as Erk, JNK, and p38 appeared not to be involved. Furthermore, inhibition of Akt/PI3K signaling pathway with wortmannin significantly, albeit not completely, abolished CG-induced Akt phosphorylation and anti-inflammatory actions. Taken together, the present study demonstrates that Akt signaling pathway might play a major role in CG-mediated anti-inflammatory activity in LPS-stimulated RAW264.7 macrophage cells.

Aromadendrin Inhibits Lipopolysaccharide-Induced Nuclear Translocation of NF-κB and Phosphorylation of JNK in RAW 264.7 Macrophage Cells

Aromadendrin, a flavonol, has been reported to possess a variety of pharmacological activities such as anti-inflammatory, antioxidant, and anti-diabetic properties. However, the underlying mechanism by which aromadendrin exerts its biological activity has not been extensively demonstrated. The objective of this study is to elucidate the anti-inflammatory mechanism of aromadedrin in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells. Aromadendrin significantly suppressed LPS-induced excessive production of pro-inflammatory mediators such as nitric oxide (NO) and PGE2. In accordance, aromadendrin attenuated LPSinduced overexpression iNOS and COX-2. In addition, aromadendrin significantly suppressed LPS-induced degradation of IκB, which sequesters NF-κB in cytoplasm, consequently inhibiting the nuclear translocation of pro-inflammatory transcription factor NF- κB. To elucidate the underlying signaling mechanism of anti-inflammatory activity of aromadendrin, MAPK signaling pathway was examined. Aromadendrin significantly attenuated LPS-induced activation of JNK, but not ERK and p38, in a concentration-dependent manner. Taken together, the present study clearly demonstrates that aromadendrin exhibits anti-inflammatory activity through the suppression of nuclear translocation of NF-κB and phosphorylation of JNK in LPS-stimulated RAW 264.7 macrophage cells.

3,4,5-Trihydroxycinnamic Acid Inhibits Lipopolysaccharide-Induced Inflammatory Response through the Activation of Nrf2 Pathway in BV2 Microglial Cells

3,4,5-Trihydroxycinnamic acid (THC) is a derivative of hydroxycinnamic acids, which have been reported to possess a variety of biological properties such as anti-inflammatory, anti-tumor, and neuroprotective activities. However, biological activity of THC has not been extensively examined. Recently, we reported that THC possesses anti-inflammatory activity in LPS-stimulated BV2 microglial cells. However, its precise mechanism by which THC exerts anti-inflammatory action has not been clearly identified. Therefore, the present study was carried out to understand the anti-inflammatory mechanism of THC in BV2 microglial cells. THC effectively suppressed the LPS-induced induction of pro-inflammatory mediators such as NO, TNF-α, and IL-1β. THC also suppressed expression of MCP-1, which plays a key role in the migration of activated microglia. To understand the underlying mechanism by which THC exerts these anti-inflammatory properties, involvement of Nrf2, which is a cytoprotective transcription factor, was examined. THC resulted in increased phosphorylation of Nrf2 with consequent expression of HO-1 in a concentration-dependent manner. THC-induced phosphorylation of Nrf2 was blocked with SB203580, a p38 MAPK inhibitor, indicating that p38 MAPK is the responsible kinase for the phosphorylation of Nrf2. Taken together, the present study for the first time demonstrates that THC exerts anti-inflammatory properties through the activation of Nrf2 in BV2 microglial cells, suggesting that THC might be a valuable therapeutic adjuvant for the treatment of inflammation-related disorders in the CNS.

Avicularin Inhibits Lipopolysaccharide-Induced Inflammatory Response by Suppressing ERK Phosphorylation in RAW 264.7 Macrophages

suppresAvicularin, quercetin-3-α-L-arabinofuranoside, has been reported to possess diverse pharmacological properties such as anti-inflammatory and anti-infectious effects. However, the underlying mechanism by which avicularin exerts its anti-inflammatory activity has not been clearly demonstrated. This study aimed to elucidate the anti-inflammatory mechanism of avicularin in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells. Avicularin significantly inhibited LPS-induced excessive production of pro-inflammatory mediators such as nitric oxide (NO) and PGE₂ and the protein levels of iNOS and COX-2, which are responsible for the production of NO and PGE₂, respectively. Avicularin also suppressed LPS-induced overproduction of pro-inflammatory cytokine IL-1β. Furthermore, avicularin significantly suppressed LPS-induced degradation of IκB, which retains NF-κB in the cytoplasm, consequently inhibiting the transcription of pro-inflammatory genes by NF-κB in the nucleus. To understand the underlying signaling mechanism of anti-inflammatory activity of avicularin, involvement of multiple kinases was examined. Avicularin significantly attenuated LPS-induced activation of ERK signaling pathway in a concentration-dependent manner. Taken together, the present study clearly demonstrates that avicularin exhibits anti-inflammatory activity through the suppression of ERK signaling pathway in LPS-stimulated RAW 264.7 macrophage cells.

Inhibition of microglia activation as a phenotypic assay in early drug discovery

Complex biological processes such as inflammation, cell death, migration, proliferation, and the release of biologically active molecules can be used as outcomes in phenotypic assays during early stages of drug discovery. Although target-based approaches have been widely used over the past decades, a disproportionate number of first-in-class drugs have been identified using phenotypic screening. This review details phenotypic assays based on inhibition of microglial activation and their utility in primary and secondary screening, target validation, and pathway elucidation. The role of microglia, both in normal as well as in pathological conditions such as chronic neurodegenerative diseases, is reviewed. Methodologies to assess microglia activation in vitro are discussed in detail, and classes of therapeutic drugs known to decrease the proinflammatory and cytotoxic responses of activated microglia are appraised, including inhibitors of glutaminase, cystine/glutamate antiporter, nuclear factor κB, and mitogen-activated protein kinases.

Protective action of erythropoietin on neuronal damage induced by activated microglia

Inflammation is a physiological defense response, but may also represent a potential pathological process in neurological diseases. In this regard, microglia have a crucial role in either progression or amelioration of degenerative neuronal damage. Because of the role of hypoxia in pro-inflammatory mechanisms in the nervous system, and the potential anti-inflammatory protective effect of erythropoietin (Epo), we focused our investigation on the role of this factor on activation of microglia and neuroprotection. Activation of microglial cells (EOC-2) was achieved by chemical hypoxia induced by cobalt chloride (CoCl2 ) and characterized by increased levels of nitrite, tumor necrosis factor-α and reactive oxygen species production, as well as up-regulation of inducible nitric oxide synthase expression. Under these conditions, cell proliferation data and proliferating cell nuclear antigen (PCNA) staining demonstrated a mitogenic effect of chemical hypoxia. Even though pre-treatment with Epo did not prevent nitrite production, inducible nitric oxide synthase protein expression or tumor necrosis factor-α secretion, it prevented the oxidative stress induced by CoCl2 as well as cell proliferation. Neuronal cells (SH-SY5Y) cultured in the presence of conditioned medium from activated EOC-2 cells or macrophages (RAW 264.7) developed significant apoptosis, an effect that was abolished by Epo via Epo/Epo receptor activation. The results show that even though Epo did not exert a direct anti-inflammatory effect on microglia activation, it did increase the resistance of neurons to subsequent damage from pro-inflammatory agents. In addition to its anti-apoptotic ability, the Epo antioxidant effect may have an indirect influence on neuronal survival by modulation of the pro-inflammatory environment.

3,4,5-Trihydroxycinnamic Acid Inhibits LPS-Induced iNOS Expression by Suppressing NF-κB Activation in BV2 Microglial Cells

Although various derivatives of caffeic acid have been reported to possess a wide variety of biological activities such as neuronal protection against excitotoxicity and anti-inflammatory property, the biological activity of 3,4,5-trihydroxycinnamic acid (THC), a derivative of hydroxycinnamic acids, has not been clearly examined. The objective of the present study is to evaluate the anti-inflammatory effects of THC on lipopolysaccharide (LPS)-stimulated BV2 microglial cells. THC significantly suppressed LPS-induced excessive production of nitric oxide (NO) and expression of iNOS, which is responsible for the production of iNOS. THC also suppressed LPS-induced overproduction of pro-inflammatory cytokines such as IL-1β and TNF-α in BV2 microgilal cells. Furthermore, THC significantly suppressed LPS-induced degradation of IκB, which retains NF-κB in the cytoplasm. Therefore, THC attenuated nuclear translocation of NF-κB, a major pro-inflammatory transcription factor. Taken together, the present study for the first time demonstrates that THC exhibits anti-inflammatory activity through the suppression of NF-κB transcriptional activation in LPS-stimulated BV2 microglial cells.

Regulation by lipocalin-2 of neuronal cell death, migration, and morphology

A secreted protein, lipocalin-2 (LCN2), has been previously shown to regulate a variety of cellular phenotypes such as cell death, migration, and morphology. The role of LCN2, however, appears to be different depending on the cellular context. Here, we investigated how LCN2 influences neuronal phenotypes by using primary cortical neuronal cell cultures and neuroblastoma cell lines as a model. When exposed to LCN2 protein, neurons and neuroblastoma cells were sensitized to cell death evoked by nitric oxide, oxidative stress, and tumor necrosis factor-α (TNF-α). A forced expression of lcn2 in glia enhanced neuronal cell death in cocultures of glia and neurons, indicating that both exogenous protein addition and endogenous expression of lcn2 give rise to similar results. Iron and BCL2-interacting mediator of cell death (BIM) protein were involved in LCN2-induced cell death sensitization, based on the studies using iron donor, chelator, siderophore, and short hairpin RNA (shRNA)-mediated knockdown of bim expression. Furthermore, cell migration assay and immunofluorescence microscopic observation revealed that LCN2 accelerated neuronal motility and process extension, suggesting multiple roles for LCN2 in the regulation of neuronal cell death, migration, and morphology.

Identification of KT-15073 as an inhibitor of lipopolysaccharide-induced microglial activation

Neuroinflammation has recently been implicated as an important mechanism responsible for the progression of neurodegenerative diseases. Activated microglia produce various proinflammatory cytokines and nitric oxide (NO) that are toxic to neurons. Thus, inhibition of microglial activation may alleviate neuroinflammatory and neurodegenerative processes. Among several fluorovinyloxyacetamide derivatives that were screened by microglia cell-based assay, a novel synthetic compound KT-15073 was identified to strongly attenuate the microglial production of NO and tumor necrosis factor-alpha (TNF-alpha). This compound also suppressed the gene expression of interleukin-1beta, inducible nitric oxide synthase, and TNF-alpha. KT-15073 inhibited the nuclear translocation and DNA binding of nuclear factor-kappaB as well as phosphorylation of p38 mitogen-activated protein kinase. In addition, KT-15073 reduced the cytotoxicity of lipopolysaccharide (LPS)-stimulated microglia toward B35 neuroblastoma cells in the microglia/neuroblastoma coculture, suggesting that the compound might exhibit the neuroprotective activity. Thus, KT-15073 has an anti-inflammatory activity in microglia, and may have a therapeutic potential for the treatment of neuroinflammatory or neurodegenerative diseases.

Sea cucumber, Stichopus japonicus ethyl acetate fraction modulates the lipopolysaccharide induced iNOS and COX-2 via MAPK signaling pathway in murine macrophages

The sea cucumber Stichopus japonicus is an important food and traditional medicine in Asian countries. However, ethyl acetate solvent fraction of S. japonicus (SCEA-F) is largely unknown for its anti-inflammatory activity and related molecular mechanisms. In this study, effect of SCEA-F on inflammation was investigated in LPS stimulated RAW264.7 cells. SCEA-F significantly inhibited the productions of NO and PGE(2) by inhibiting iNOS and COX-2 at their protein and gene levels. The production and the gene transcription of pro-inflammatory cytokines are also inhibited. The responsible molecular signaling for these inhibitory actions was found to be through suppression of the phosphorylation of MAPK molecules; ERK and p38 MAPK. These results indicate that SCEA-F inhibits LPS-induced inflammatory response via blocking of MAPK signaling pathway in murine macrophages, thus demonstrated its in vitro anti-inflammatory potential. Therefore it could be suggested that SCEA-F could be effectively used in functional food preparations.

Tetramethylpyrazine inhibits production of nitric oxide and inducible nitric oxide synthase in lipopolysaccharide-induced N9 microglial cells through blockade of MAPK and PI3K/Akt signaling pathways, and suppression of intracellular reactive oxygen species

AIM OF THE STUDY

To determine the inhibitory effect of tetramethylpyrazine (TMP) on lipopolysaccharide (LPS)-induced over-production of nitric oxide (NO) and inducible nitric oxide synthase (iNOS) in N9 microglial cells.

MATERIALS AND METHODS

N9 cells were pretreated with vehicle or TMP and then exposed to LPS for the time indicated. Cell viability was determined by methylthiazoyltetrazolium (MTT) assay. Nitrite assay was performed by Griess reaction. Expression of iNOS mRNA was examined by RT-PCR. Protein levels of iNOS, p38 mitogen-activated protein kinase (MAPK), ERK1/2, JNK, phosphatidylinositol 3-kinase (PI3K) and Akt were determined by western blot analysis. Formation of reactive oxygen species (ROS) was evaluated by fluorescence image system.

RESULTS

TMP inhibited LPS-induced over-production of NO and iNOS in N9 cells. TMP also inhibited the NF-kappaB translocation from cytoplasm into nucleus of N9 cells. In addition, TMP showed blocking effect on the phosphorylation of p38 MAPK, ERK1/2, JNK and Akt, but not PI3K. Further, TMP suppressed the formation of intracellular ROS in LPS-induced N9 cells.

CONCLUSIONS

TMP inhibited production of NO and iNOS in LPS-induced N9 cells through blocking MAPK and PI3K/Akt activation and suppressing ROS production.

Anti-inflammatory effects of synthetic compound KT-14480 in lipopolysaccharide-stimulated microglia cells

Objectives

Neurodegenerative diseases have a prominent inflammatory component. Several synthetic fluorovinyloxyacetamide derivatives were screened by microglia cell-based assay in order to identify novel compounds that inhibit the inflammatory activation of microglia.

Methods

Microglia cell-based nitric oxide assay was employed to screen the compounds. RT-PCR and ELISA were conducted to evaluate the expression of inflammatory gene expression. Molecular mechanisms were determined by western blot analysis, immunocytochemistry, EMSA, and microglia/neuroblastoma cocultures.

Key findings

A fluorovinyloxyacetamide compound KT-14480 significantly suppressed nitric oxide production in lipopolysaccharide-stimulated microglia cells. KT-14480 also suppressed the secretion and expression of several inflammatory mediators such as tumour necrosis factor-α, interleukin-1β and inducible nitric oxide synthase. Additional studies showed that these inhibitory effects were accompanied by the suppression of nuclear factor-κB and neuroprotection in the microglia/neuroblastoma coculture.

Conclusions

Our results indicate that the anti-inflammatory compound KT-14480 may be a novel therapeutic drug candidate against neuroinflammatory diseases.