UNIPROT:P43026 - FACTA Search

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Query: UNIPROT:P43026 (lipopolysaccharide)
62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In response to neurotransmitters, astrocytes show various types of calcium increase (transient, oscillatory, and complex), the physiological significance of which is still controversial. To explore this variability, we examined factors affecting the calcium increase pattern in cultured astrocytes and investigated the consequences of the astrocytic calcium response in slice preparations. We found that growth factors (GFs) (EGF plus basic FGF) promoted calcium oscillation in response to glutamate, ATP, or thimerosal (which directly activates the inositol-1,4,5 triphosphate receptor) and that this effect was suppressed by pro-inflammatory cytokines (interleukin-1beta or tumor necrosis factor-alpha), lipopolysaccharide, or a MEK (mitogen-activated protein kinase kinase) inhibitor, suggesting dual regulation of calcium oscillation in astrocytes by factors affecting brain function and pathology via the mitogen-activated protein kinase (MAPK) cascade. The calcium oscillation was accompanied by enlargement of the calcium store, cell proliferation, and the development of a hypertrophic morphology. The cytokines suppressed GF-induced MAPK-dependent immediate early gene promoter activation, but not phosphorylation of extracellular signal-regulated kinase (ERK), showing that they affected gene regulation by acting on the MAPK cascade downstream of ERK. In slice preparations, a metabotropic glutamate receptor agonist converted the spontaneous neuronal calcium increase, attributable to synaptic transmission, to an oscillatory response similar to that seen in astrocytes in culture, indicating that the calcium response in astrocytes acted as a feedback mechanism on the activity of neighboring neurons. This is the first evidence for a dual regulation of calcium oscillation by physiological factors and for the control of calcium dynamics actually being used in physiological processes.
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PMID:Dual regulation of calcium oscillation in astrocytes by growth factors and pro-inflammatory cytokines via the mitogen-activated protein kinase cascade. 1464 90

Toll-like receptors (TLR) have been described as partially sharing signalling pathways but showing unique ligand specificity and tissue distribution. Here, the response of bovine macrophages (Mphi) and dendritic cells (DC), both derived from monocytes, was compared by exposing them to the TLR-specific ligands lipopolysaccharide, poly(I:C)-double-stranded RNA, and CpG-DNA, as well as inactivated Gram-negative and Gram-positive bacteria, shown to bind to TLR. The production of NO, superoxide anion, interleukin-10 (IL-10), IL-12 and tumour necrosis factor (TNF) was determined. Compared to monocytes, Mphi expressed more TLR2 and similar levels of TLR4 mRNA transcripts, as analysed by quantitative polymerase chain reaction, whereas DC expressed reduced amounts. Although both DC and Mphi recognized the TLR ligands, dramatic differences were seen in their reaction pattern to them. Both cell types responded with the production of TNF, but DC produced more IL-12, whereas Mphi produced more IL-10, regardless of the TLR agonist used. Co-stimulation with interferon-gamma influenced the amount of cytokine production, but did not alter the cell type-specific response pattern. Compared to Mphi, DC produced > 10 times less NO upon triggering with TLR ligands. In addition, DC produced superoxide anion to opsonized and non-opsonized zymosan, but not to phorbol 12-myristate 13-acetate, a response pattern confirmed for human Mphi and DC, respectively. Different protein kinase C isoforms and extracellular signal-regulated kinase patterns were detected in cell lysates of resting and stimulated Mphi and DC. Collectively, our results point to profound differences in pathogen-derived signal-response coupling occurring commensurate with distinct functions carried out by Mphi or DC.
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PMID:Differential production of cytokines, reactive oxygen and nitrogen by bovine macrophages and dendritic cells stimulated with Toll-like receptor agonists. 1467 98

1. The present study was undertaken to investigate the anti-inflammatory effects of a synthetic compound, LCY-2-CHO, on the expression of inducible nitric oxide synthase (iNOS), COX-2, and TNF-alpha in murine RAW264.7 macrophages. 2. Within 1-30 microm, LCY-2-CHO concentration-dependently inhibited lipopolysaccharide (LPS)-induced nitric oxide (NO), prostaglandin E(2) (PGE(2)), and tumor necrosis factor-alpha (TNF-alpha) formation, with IC(50) values of 2.3, 1, and 0.8 microm, respectively. Accompanying inhibition of LPS-induced iNOS, cyclooxygenase-2 (COX-2), and pro-TNF-alpha proteins was observed. 3. Reverse transcription-polymerase chain reaction (RT-PCR) and promoter analyses indicated that iNOS expression was inhibited at the transcriptional level (IC(50)=2.3 microm), that inhibition of COX-2 expression only partially depended on gene transcription (IC(50)=7.6 microm), and that TNF-alpha transcription was unaffected. 4. Transcriptional assays revealed that activation of AP-1, but not NF-kappaB, was concomitantly blocked by LCY-2-CHO. Our results showed that LCY-2-CHO was capable of interfering with post-transcriptional regulation, altering the stability of COX-2 and TNF-alpha mRNAs. 5. Since the 3'-untranslated region (3' UTR) of both COX-2 and TNF-alpha mRNA contains a p38 mitogen-activated protein kinase (MAPK)-regulated element involved in mRNA stability, we assessed the effect of LCY-2-CHO on p38 MAPK. Our data clearly indicated an inhibition (IC(50)=1.7 microm) of LPS-mediated p38 MAPK activity, but not of extracellular signal-regulated kinase (ERK) or c-Jun N-terminal kinase (JNK) activity. However, kinase assays ruled out a direct inhibition of p38 MAPK action. The selective p38 MAPK inhibitor, SB203580, inhibited the promoter activities of iNOS and COX-2 rather than that of TNF-alpha. 6. In conclusion, LCY-2-CHO downregulates inflammatory iNOS, COX-2, and TNF-alpha gene expression in macrophages through interfering with p38 MAPK and AP-1 activation.
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PMID:The anti-inflammatory carbazole, LCY-2-CHO, inhibits lipopolysaccharide-induced inflammatory mediator expression through inhibition of the p38 mitogen-activated protein kinase signaling pathway in macrophages. 1498 Sep 80

It has been widely shown that many plant-derived compounds present significant anti-inflammatory effects. For this reason, they represent potential molecules for the development of new drugs, especially designed for the treatment and/or control of chronic inflammatory states such as rheumatism, asthma, inflammatory bowel diseases, atherosclerosis, etc. This review focuses on the naturally-occurring compounds with anti-inflammatory properties and attempts to correlate their actions with the modulation of cytokines and associated intracellular signalling pathways; it continues the review published in the November, 2003 issue of Planta Medica. Abbreviations. AP-1:activator protein-1 CCR1:chemokine receptor 1 CINC-1:cytokine-induced neutrophil chemoattractant 1 COX:cyclooxygenase EGCG:(-)-epigallocatechin gallate ELAM-1:endothelial-leukocyte adhesion molecule-1 ERK:extracellular signal-regulated kinase GRO:growth-related oncogene HUVEC:human umbilical vein endothelial cells ICAM-1:intercellular adhesion molecule-1 IFN:interferon IL:interleukin iNOS:inducible nitric oxide synthase IRA:the natural interleukin receptor activation JAK:janus kinase JNK:c-Jun NH2-terminal kinase LPS:lipopolysaccharide MAPK:mitogen-activated protein kinases MCP:monocyte chemotactic protein MHC:major histocompatibility complex MIP:macrophage inflammatory protein MMP:matrix metalloproteinases MPO:myeloperoxidase NF-kappaBnuclear factor kappa B NO:nitric oxide PAF:platelet aggregation factor PGEE:prostaglandin PK:protein kinase PMA/TPA:phorbol myristate acetate RANTES:regulated upon activation normal T-cell expressed and secreted TGF-beta:transforming growth factor-beta TNFalpha:tumour necrosis factor VCAM-1:vascular cell adhesion molecule-1
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PMID:Anti-inflammatory compounds of plant origin. Part II. modulation of pro-inflammatory cytokines, chemokines and adhesion molecules. 1499 84

Mitogen-activated protein kinases (MAPKs) are thought to have a critical role in lipopolysaccharide (LPS)-induced immune responses but the molecular mechanisms underlying the mediation of these signaling are not clear. The roles of p38 and extracellular signal-regulated kinase (ERK) in the regulation of nitric oxide (NO) and proinflammatory cytokine expression in J774A.1 macrophages in response to LPS were examined. Specific inhibitors for p38 and ERK, SB203580 and PD98059, respectively, were used. LPS (30ng/ml) activated inducible nitric oxide synthase (iNOS), subsequent NO production, and gene expression for tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1beta, IL-6, and IL-12. Treatment of cultures with SB203580 increased LPS-induced reactive oxygen species (ROS) production, whereas both SB203580 and PD98059 decreased LPS-induced NO production. Concomitant decreases in the expression of iNOS mRNA and protein were detected. SB203580 and PD98059 decreased LPS-induced gene expression of IL-1beta and IL-6. SB203580 increased LPS-induced expression of TNF-alpha and IL-12; PD98059 had no effect on these cytokines. Results indicated that both p38 and ERK pathways are involved in LPS-stimulated NO synthesis and the expression of IL-1beta and IL-6. p38 signaling pathway is involved in LPS-induced ROS, TNF-alpha and IL-12 production.
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PMID:Inhibition of p38 and ERK MAP kinases blocks endotoxin-induced nitric oxide production and differentially modulates cytokine expression. 1499 52

Activation of the nuclear enzyme poly(ADP-ribose) polymerase (PARP) is involved in numerous pathophysiological conditions. Because PARP-1 knockout mice are resistant to endotoxin-induced shock and inhibitors of the enzyme were reported to have similar beneficial properties, we investigated the effect of 4-hydroxyquinazoline (4-HQN), a potent PARP-1 inhibitor, on the modulation of kinase cascades and the regulation of transcription factors in a rodent septic shock model. T2-weighted magnetic resonance imaging showed the pattern of anatomical localization of the inflammatory response in bacterial lipopolysaccharide (LPS)-treated mice and the anti-inflammatory effect of the PARP-1 inhibitor. We have found that 4-HQN activated the phosphatidylinositol 3 (PI3)-kinase/Akt pathway in lung, liver, and spleen, and down-regulated two elements of the MAP kinase system. Namely, it dramatically attenuated the activation of the LPS-induced extracellular signal-regulated kinase (ERK)1/2 and p38 mitogen-activated protein (MAP) kinase in a tissue-specific manner. Furthermore, phosphorylation of p90RSK, a downstream target of ERK1/2, showed a similar pattern of down-regulation as did the phosphorylation of ERK1/2 and p38 after LPS and 4-HQN treatment. As a consequence of the aforementioned effects on the kinase pathways, 4-HQN decreased the activation of transcription factor nuclear factor-kappaB (NF-kappaB) and activator protein 1 (AP-1) in LPS-induced endotoxic shock. Our results provide evidence for the first time that the beneficial effects of PARP inhibition in endotoxic shock, such as attenuation of NF-kappaB- and AP-1 transcription factor activation, are mediated, at least partially, through the regulation of the PI3-kinase/Akt pathway and MAP kinase cascades.
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PMID:Regulation of kinase cascades and transcription factors by a poly(ADP-ribose) polymerase-1 inhibitor, 4-hydroxyquinazoline, in lipopolysaccharide-induced inflammation in mice. 1499 56

Actinobacillus actinomycetemcomitans is a major periodontopathic bacterium with multiple virulence factors, including lipopolysaccharide (LPS). Previous reports have demonstrated that LPS induced apoptosis in a murine macrophage-like cell line, J744.1, as well as in peritoneal macrophages from C3H/HeN mice in the presence of cycloheximide (CHX). However, the detailed molecular mechanisms involved in the apoptosis of macrophages induced by LPS and CHX are not well known. To clarify the possible role of LPS in the induction of macrophage apoptosis, we investigated cell death induced by LPS from A. actinomycetemcomitans and CHX in human macrophage-like U937 cells, which were differentiated by 12-O-tetradecanoylphorbol 13-acetate (TPA), and also assessed the molecular mechanisms involved in the process. We found that TPA-differentiated U937 cells usually showed resistance to LPS-induced apoptosis. However, in the presence of CHX, LPS induced release of cytochrome c without modifying steady-state levels of Bcl-2, Bcl-xL, Bax, and Bak. Treatment with LPS in the presence of CHX also led to activation of caspase-3 and apoptosis via, in part, the CD14/toll-like receptor 4 (TLR4). The induction of cytochrome c release may have been due to dephosphorylation of Akt and Bad, which were cooperatively induced by CHX and LPS. However, endogenous tumor necrosis factor alpha- and Fas-induced signals, extracellular signal-regulated kinase kinase/mitogen-activated protein kinases and I-kappa B alpha/nuclear factor-kappa B (NF-kappa B) were not required for caspase-3-dependent apoptosis. These results emphasize the possible important role of the mitochondrial apoptotic pathway leading to caspase-3 activation in LPS-induced apoptosis of human macrophages in the presence of CHX.
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PMID:Mechanisms involved in apoptosis of human macrophages induced by lipopolysaccharide from Actinobacillus actinomycetemcomitans in the presence of cycloheximide. 1503 4

CD14 is important in the clearance of bacterial pathogens from lungs. However, the mechanisms that regulate the expression of membrane CD14 (mCD14) on alveolar macrophages (AM) have not been studied in detail. This study examines the regulation of mCD14 on AM exposed to Escherichia coli in vivo and in vitro, and explores the consequences of changes in mCD14 expression. The expression of mCD14 was decreased on AM exposed to E. coli in vivo and AM incubated with lipopolysaccharide (LPS) or E. coli in vitro. Polymyxin B abolished LPS effects, but only partially blocked the effects of E. coli. Blockade of extracellular signal-regulated kinase pathways attenuated LPS and E. coli-induced decrease in mCD14 expression. Inhibition of proteases abrogated the LPS-induced decrease in mCD14 expression on AM and the release of sCD14 into the supernatants, but did not affect the response to E. coli. The production of tumor necrosis factor-alpha in response to a second challenge with Staphylococcus aureus or zymosan was decreased in AM after incubation with E. coli but not LPS. These studies show that distinct mechanisms regulate the expression of mCD14 and the induction of endotoxin tolerance in AM, and suggest that AM function is impaired at sites of bacterial infection.
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PMID:Differential regulation of membrane CD14 expression and endotoxin-tolerance in alveolar macrophages. 1505 84

Triptolide (PG490) is a natural, biologically active compound extracted from the Chinese herb Tripterygium wilfordii. It has been shown to possess potent anti-inflammatory and immunosuppressive properties. In Raw 264.7 cells stimulated with lipopolysaccharide (LPS) to mimic inflammation, triptolide inhibits nitric oxide (NO) production in a dose-dependent manner and abrogates inducible nitric oxide synthase (iNOS) gene expression. To investigate the mechanism by which triptolide inhibits murine iNOS gene expression, we examined activation of mitogen-activated protein kinases (MAP kinases) and nuclear factor-kappa B (NF-kappa B) in these cells. Addition of triptolide inhibited phosphorylation of c-Jun NH(2)-terminal kinase (JNK) but not that of extracellular signal-regulated kinase (ERK) or p38 mitogen-activated protein kinase. In addition, triptolide significantly inhibited the DNA binding activity of NF-kappa B. Taken together, these results suggest that triptolide acts to inhibit inflammation through inhibition of NO production and iNOS expression through blockade of NF-kappa B and JNK activation.
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PMID:Triptolide inhibits murine-inducible nitric oxide synthase expression by down-regulating lipopolysaccharide-induced activity of nuclear factor-kappa B and c-Jun NH2-terminal kinase. 1519 45

Inflammatory cytokine production by alveolar macrophages (AMs) is regulated by transcriptional activation and may be increased by cigarette smoking. The smoking-induced regulation of interleukin (IL)-8 by extracellular signal-regulated kinase (ERK)-1 and -2, p38 mitogen-activated protein kinase (MAPK) and the transcription factor nuclear factor-kappaB (NF-kappaB) in lipopolysaccharide-stimulated AMs was assessed in nine smokers compared with nine healthy nonsmokers. IL-8 production was dependent on phosphorylation of ERK-1 and -2 and p38 MAPK, as examined by PD 098059 (10 microM), an inhibitor of the upstream activator of MAPK kinase (MKK)-1, and SB 203580 (10 microM), an inhibitor of p38 MAPK. IL-8 release and the inhibitory effect of PD 098059 were increased in AMs from smokers. Moreover, ERK-2 messenger ribonucleic acid expression, as examined by reverse transcriptase polymerase chain reaction and phosphorylation of ERK-2 using Western blots, were increased in AMs from smokers, indicating a smoking-induced modulatory role of ERK-1 and -2. Lipopolysaccharide-induced IL-8 production was dependent on activation of NF-kappaB, as examined by SN 50 (100 microM), an inhibitor of NF-kappaB translocation, and the specific NF-kappaB inhibitor kinase-2 inhibitor, AS 602868 (10 microM), with no differences in AMs from smokers and nonsmokers. SN 50 but not PD 098059 and SB 203580 blocked NF-kappaB deoxyribonucleic acid-binding, and this occurred to the same extent in AMs from smokers and nonsmokers, as examined by electromobility shift assay. It is concluded that cigarette smoking enhances mitogen-activated protein kinase activation more than nuclear factor-kappaB activation to increase lipopolysaccharide-induced interleukin-8 production in alveolar macrophages.
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PMID:Effect of smoking on MAP kinase-induced modulation of IL-8 in human alveolar macrophages. 1521 90

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