Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P43026 (lipopolysaccharide)
 62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Dexamethasone inhibits lipopolysaccharide-induced synthesis of the cytokine, interleukin-1 beta, in cerebrospinal fluid of patients with bacterial meningitis. Along with monocytes, astrocytes are capable of producing lipopolysaccharide-induced interleukin-1 beta in the central nervous system. The objective of this study was to investigate the induction of interleukin-1 beta mRNA by lipopolysaccharide, and the inhibition of this process by dexamethasone, in human astrocytes using the astrocytoma cell line U-373MG as a model system. Dexamethasone-mediated inhibition of induction of interleukin-1 beta mRNA by lipopolysaccharide required a functional glucocorticoid receptor. In contrast to monocytes, lipopolysaccharide induction of interleukin-1 beta mRNA in U-373MG cells required de novo protein synthesis. Dexamethasone also had no effect on lipopolysaccharide-induced interleukin-1 beta transcriptional initiation in U-373MG cells. U-373MG cells were similar to monocytes, however, with respect to the ability of dexamethasone to decrease interleukin-1 beta mRNA half-life. These findings demonstrate that the mode of lipopolysaccharide induction of interleukin-1 beta mRNA, and inhibition of this process by dexamethasone, can vary in different cell types.
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PMID:Protein synthesis-dependent induction of interleukin-1 beta by lipopolysaccharide is inhibited by dexamethasone via mRNA destabilization in human astroglial cells. 759 67

The objective of adjunct anti-inflammatory therapy of bacterial meningitis is the containment of heightened inflammation caused by lysis of bacteria by antibiotics. This can be modelled by giving two consecutive intra-cisternal injections of lipopolysaccharide (LPS) to rabbits, the first at 0 h to induce inflammation to mimic that occurring during the proliferation of bacteria in the cerebrospinal fluid (CSF), and the second at 6 h to mimic inflammation subsequent to antibiotic-induced bacterial lysis. Injection of 2.5 ng of LPS induced pleocytosis at 4 h which was preceded by a peak of tumour necrosis factor (TNF) activity at 2 h. A subsequent injection of 25 ng of LPS at 6 h induced second peaks of pleocytosis and CSF TNF. Dexamethasone (1.5 mg/kg, i.v.) administered 15 min or 1 h before the second injection of LPS tended only to reduce CSF TNF, but effectively prohibited further pleocytosis. Brain TNF alpha mRNA levels were unchanged at 6 and 7 h after LPS injection, and were unaffected by dexamethasone. These results indicate that the subarachnoid space is distinct from the general circulation in that the TNF-producing cells present do not display a hypo-responsive state towards LPS as occurs when LPS is injected systemically. Furthermore, dexamethasone is able to attenuate the secondary inflammatory response resulting from a second LPS injection without eliminating a second peak of TNF activity.
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PMID:Dexamethasone treatment of lipopolysaccharide-induced meningitis in rabbits that mimics magnification of inflammation following antibiotic therapy. 760 53

Transport of L-arginine and generation of nitrite in microglia-free astroglial cultures derived from neonatal mouse brain were stimulated by bacterial lipopolysaccharide (LPS) in a time- and dose-dependent manner. LPS stimulated arginine transport between 1.3- and 2.5-fold; half-maximal stimulation was obtained with 0.3 micrograms/ml LPS. Acceleration of transport was detectable within 6 h of incubation with LPS. Cycloheximide or actinomycin D neutralized the effect of LPS. Stimulation of generation of nitrite was reduced when the cells were incubated simultaneously with LPS and either genistein or diethyldithiocarbamate, inhibitors of protein tyrosine kinase and nuclear transcription factor kappa, respectively. However, stimulation of arginine transport was not reduced in the presence of these compounds. Dexamethasone inhibited stimulation of nitric oxide (NO) production but not of arginine transport. Protein kinase C inhibitor staurosporine had no effect on either process. The results suggest that LPS-stimulated acceleration of arginine transport in astrocytes requires protein as well as RNA synthesis. Induction of synthesis of an astroglial cationic amino acid transport system appears to be mechanistically independent from stimulation of intracellular NO production.
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PMID:Stimulation of arginine transport and nitric oxide production by lipopolysaccharide is mediated by different signaling pathways in astrocytes. 761 13

Macrophage inflammatory protein 1 (MIP-1) is a recently characterized inflammatory and chemokinetic cytokine. Proinflammatory stimuli have been shown to induce expression of MIP-1 by macrophages. We hypothesized that microglia and astrocytes express MIP-1 alpha because of their many immunologic similarities to macrophages. MIP-1 alpha mRNA was examined with quantitative reverse transcription and polymerase chain reaction in an immortalized mouse microglial cell line (BV-2) and in mouse cortical astrocyte cultures. We found that in both the BV-2 microglial cell line and in astrocyte cultures, MIP-1 alpha mRNA was strongly induced by lipopolysaccharide and the phorbol ester PMA. MIP-1 alpha mRNA was reduced by dBcAMP, interferon-gamma, and PGE1. Dexamethasone decreased MIP-1 alpha mRNA levels in astrocyte cultures, but not in BV-2 microglial cells. Interleukin-1 beta, tumor necrosis factor alpha, and MIP-1 alpha had no effect on MIP-1 alpha mRNA expression. These findings demonstrate that MIP-1 alpha mRNA is expressed by cultured glial cells and is regulated by proinflammatory and anti-inflammatory stimuli. MIP-1 alpha may be expressed by microglia and astrocytes in vivo, and may help modulate cerebral inflammation.
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PMID:Macrophage inflammatory protein 1-alpha mRNA expression in an immortalized microglial cell line and cortical astrocyte cultures. 762 89

Nitric oxide (NO.) is a short-lived mediator which can be induced in a variety of cell types and produces many physiologic and metabolic changes in target cells. The inducible or high-output NO. synthase (NOS) pathway was first characterized in macrophages activated by lipopolysaccharide (LPS) and interferon gamma (IFN-gamma). Hepatocytes also express an inducible NOS following exposure to the combination of endotoxin (LPS) and tumor necrosis factor (TNF), interleukin 1 (IL-1), and IFN-gamma. In this study, to identify which of these cytokines, if any, was acting to induce the gene expression for hepatocyte NOS, we measured the levels of rat hepatocyte NOS mRNA by Northern blot analysis after stimulation by various combinations of endotoxin and cytokines in vitro. We found the mRNA for hepatocyte NOS to be a single band at approximately 4.5 kilobases which was maximally up-regulated (approximately 70-fold) by the combination of TNF, IL-1, IFN-gamma, and LPS. Abundance of NOS mRNA peaked 6-8 hr after stimulation and then declined by 25% at 24 hr. Unstimulated hepatocytes in vitro showed only a trace mRNA band after prolonged autoradiographic exposure. As single agents, TNF and IL-1 were the most effective inducers of hepatocyte NOS mRNA. Combinations of two or three stimuli revealed strong synergy between TNF, IL-1, and IFN-gamma. The increased mRNA levels correlated with elevated nitrogen oxide release and cGMP levels in the culture supernatants. Dexamethasone and cycloheximide inhibited induction of mRNA for hepatocyte NOS in a dose-dependent fashion. The addition of NG-monomethyl-L-arginine had no effect on mRNA levels but effectively blocked NO. formation. The inducible hepatocyte NOS mRNA was also detected in rat hepatocytes following chronic hepatic inflammation triggered by Corynebacterium parvum injection in vivo. These data demonstrate that the inducible NOS is functional in rat hepatocytes both in vitro and in vivo and that this pathway is under complex control. Endotoxin and inflammatory cytokines act synergistically to up-regulate gene expression for hepatocyte NOS, whereas glucocorticoids down-regulate the mRNA.
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PMID:Cytokines, endotoxin, and glucocorticoids regulate the expression of inducible nitric oxide synthase in hepatocytes. 767 58

1. The role of an enhanced formation of nitric oxide (NO) and the relative importance of the constitutive and inducible NO synthase (NOS) for the development of immediate (within 60 min) and delayed (at 180 min) vascular hyporeactivity to noradrenaline was investigated in a model of circulatory shock induced by endotoxin (lipopolysaccharide; LPS) in the rat. 2. Male Wistar rats were anaesthetized and instrumented for the measurement of mean arterial blood pressure (MAP) and heart rate. In addition, the calcium-dependent and calcium-independent NOS activity was measured ex vivo by the conversion of [3H]-arginine to [3H]-citrulline in homogenates from several organs obtained from vehicle- and LPS-treated rats. 3. E. coli LPS (10 mg kg-1, i.v. bolus) caused a rapid (within 5 min) and sustained fall in MAP. At 30 and 60 min after LPS, pressor responses to noradrenaline (0.3, 1 or 3 micrograms kg-1, i.v.) were significantly reduced. The pressor responses were restored by NG-nitro-L-arginine methyl ester (L-NAME, 1 mg kg-1, i.v. at 60 min), a potent inhibitor of NO synthesis. In contrast, L-NAME did not potentiate the noradrenaline-induced pressor responses in control animals. 4. Dexamethasone (3 mg kg-1, i.v., 60 min prior to LPS), a potent inhibitor of the induction of NOS, did not alter initial MAP or pressor responses to noradrenaline in control rats, but significantly attenuated the LPS-induced fall in MAP at 15 to 60 min after LPS. Dexamethasone did not influence the development of the LPS-induced immediate (within 60 min) hyporeactivity to noradrenaline. However,dexamethasone pretreatment prevented the hypotension and vascular hyporeactivity at 180 min.5. At 60 min after LPS a moderate increase in the activity of a calcium-independent (inducible) NOS activity was detected in the aorta, but not in any of the other tissues studied. However, at 180 min after LPS, a significant NOS induction was observed in the lung, liver, spleen, mesentery, heart and aorta.This NOS induction was substantially prevented by pretreatment with dexamethasone.6. These results suggest that the immediate hypotension and vascular hyporeactivity to noradrenaline in endotoxin shock is caused by an enhanced formation of NO due to activation of the constitutive enzyme. The delayed hypotension and vascular hyporeactivity, however, is due to enhanced NO formation by the LPS-induced enzyme.
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PMID:Nitric oxide-mediated hyporeactivity to noradrenaline precedes the induction of nitric oxide synthase in endotoxin shock. 768 37

We investigated the effect of the calcium channel antagonist nifedipine on the induction of nitric oxide synthase (NOS) by bacterial endotoxin (lipopolysaccharide; LPS) in J774.2 macrophages, in cultured rat aortic smooth muscle cells and in a rat model of endotoxin shock. Stimulation by LPS for 24 hr increased nitrite accumulation in the supernatant of both cell types. NOS induction accounts for this nitrite accumulation, as both NG-methyl-L-arginine and cycloheximide reduced nitrite production in both cell types. Dexamethasone inhibited LPS-stimulated nitrite production in macrophages, but not in rat aortic smooth muscle cells. Nifedipine inhibited the production of nitrite in these LPS-treated cell types, with a more pronounced effect on macrophages. However, nifedipine did not inhibit the production of nitrite in J774.2 cells in which NOS had already been induced by prior exposure to LPS, and any possible further induction was inhibited by cycloheximide. In anesthetized rats subjected to LPS, pretreatment with nifedipine or dexamethasone ameliorated the fall in mean arterial blood pressure and the vascular hyporeactivity to norepinephrine at 180 min after LPS injection. At 180 min after LPS, an increase in a calcium-independent (induced) NOS activity was measured in lung homogenates. This induced NOS activity was reduced in lungs from rats treated with nifedipine or dexamethasone before LPS. Thus, nifedipine inhibits the induction of NOS in response to LPS in cultured cells in vitro and in the anesthetized rat.
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PMID:Nifedipine inhibits the induction of nitric oxide synthase by bacterial lipopolysaccharide. 768 45

The present study determined the presence of constitutive and inducible nitric oxide (NO) synthase activities in intestinal isolated epithelial cells and the effects of NO induction on intestinal epithelial cell viability. Epithelial cells were isolated from rat proximal small intestine by dispersion using citrate and EDTA. Constitutive NO synthase activity, determined by [14C]arginine conversion to citrulline that was inhibited by in vitro incubation with the arginine analogue NG-monomethyl-L-arginine (L-NMMA; 300 microM) or ethylene glycol-bis (beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA; 1 mM), was observed in these cells. Administration of Escherichia coli lipopolysaccharide (LPS; 3 mg/kg iv) significantly augmented NO synthase activity (determined 4 h later), which was inhibited in vitro by incubation with L-NMMA but not by EGTA. The highest level of constitutive and inducible NO synthase activity occurred in intestinal villus cells, and the lowest was in crypt cells. Induction of NO synthase activity was associated with a decrease in cellular viability as assessed by a decrease in trypan blue exclusion. Dexamethasone pretreatment (1 mg/kg iv 2 h before LPS administration) significantly reduced both induction of NO synthase activity and the reduction in cellular viability. Likewise concurrent administration of the NO synthase inhibitor NG-nitro-L-arginine methyl ester (10 mg/kg sc) ameliorated the reduction in cell viability induced by LPS administration, an effect abolished by pretreatment with the NO substrate L-arginine (350 mg/kg sc). Whereas constitutively formed NO may have a physiological role in these cells, the results in this study suggest that induction of NO synthase in epithelial cells may represent a mechanism of local intestinal damage.
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PMID:Nitric oxide synthase induction and intestinal epithelial cell viability in rats. 769 Jan 86

Both nitric oxide and prostaglandins are potent paracrine mediators of intercellular communication. An endotoxin-lipopolysaccharide (LPS) inducible form of nitric oxide synthase (mac-NOS) has recently been cloned from murine macrophages. An inducible prostaglandin synthase (TIS10/PGS-2), cloned from 3T3 cells, is also induced in LPS-activated macrophage. Because of the wide range of ligands that induce primary response genes in 3T3 cells, the ease of studying chimeric promoter constructs in 3T3 cells, and the importance of both nitric oxide and prostaglandins as paracrine mediators, we examined expression of mac-NOS in 3T3 cells. Tetradecanoyl phorbol-13-acetate (TPA), forskolin, platelet-derived growth factor, fibroblast growth factor, and serum all induce mac-NOS expression in Swiss 3T3 cells. Thus the mac-NOS gene can respond to a far wider range of inducers than previously suspected. mac-NOS is a primary response gene; cycloheximide does not block induction. TPA-induced mac-NOS and TIS10/PGS-2 mRNA accumulation patterns are similar. LPS is a potent inducer of mac-NOS in Swiss 3T3 cells but cannot induce TIS10/PGS-2. In contrast, v-src expression induces TIS10/PGS-2 message, but not iNOS message in a BALB/c 3T3 cell line containing a temperature-sensitive v-src gene. Dexamethasone (DEX) prevents induction of TIS10/PGS-2, but not most other primary response genes. DEX also blocks mac-NOS induction in Swiss 3T3 cells. The inducible TIS10/PGS-2 and mac-NOS genes, responsible for the production of two distinct paracrine agents, appear to share many regulatory features in 3T3 cells.
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PMID:"Macrophage" nitric oxide synthase is a glucocorticoid-inhibitable primary response gene in 3T3 cells. 769 32

Dexamethasone (DEX) is a well-known inhibitor of tumor necrosis factor (TNF) production when given shortly before lipopolysaccharide (LPS). However, DEX (10 mg/kg, ip) potentiates TNF production when administered 24-48 hr before LPS (16 micrograms/kg, ip). We have found that this is probably due to DEX induction of cytochrome P450 3A, which is known to produce nitric oxide (NO). The upregulating effect of DEX on TNF production is associated with increased NO production. Both the upregulation of NO and of TNF production by DEX are inhibited by co-administration of the P450 3A inhibitor troleandomycin (TAO, 40 mg/kg, ip). These data suggest that P450 3A-generated NO might be involved in TNF induction.
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PMID:The upregulating effect of dexamethasone on tumor necrosis factor production is mediated by a nitric oxide-producing cytochrome P450. 772 92


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