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

The mitogen-inducible cyclooxygenase (COX-2) is selectively expressed in lipopolysaccharide (LPS)-stimulated macrophages. However, the signaling pathways that lead to the expression of COX-2 in LPS-stimulated macrophages are not well understood. LPS activates members of mitogen-activated protein kinases (MAPKs) and NF-kappaB transcription factor in macrophages. We have shown that protein tyrosine kinase (PTK) inhibitors suppress the LPS-induced expression of COX-2 in macrophages (Chanmugam et al., J Biol Chem 270: 5418-5426, 1995). These PTK inhibitors also inhibit LPS-induced activation of MAPKs. Thus, in the present study, we determined whether the activation of MAPKs and NF-kappaB is necessary for the signaling pathway for the LPS-induced expression of COX-2 in the murine macrophage cell line RAW 264.7. The findings demonstrated that inhibition of extracellular signal-regulated protein kinases 1 and 2 (ERK-1 and -2) by the selective inhibitor PD98059 or inhibition of P38 by the specific inhibitor SB203580 results in partial suppression of COX-2 expression. However, activation of MAPKs by phorbol 12-myristate 13-acetate, H2O2, sorbitol, sodium vanadate, or a combination of these agents failed to induce the expression of COX-2. Inhibitors of NF-kappaB suppressed COX-2 expression without affecting tyrosine phosphorylation of MAPKs. The PTK inhibitors that suppressed the activation of MAPKs and COX-2 expression also inhibited the degradation of IkappaB-alpha. Together, these results indicate that the activation of NF-kappaB is required to induce the expression of COX-2 in LPS-stimulated RAW 264.7 cells. Inhibition of ERK-1 and 2 or P38 results in partial suppression of COX-2 expression. However, the activation of MAPKs alone is not sufficient to induce the expression of COX-2 in these cells.
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PMID:Expression of mitogen-inducible cyclooxygenase induced by lipopolysaccharide: mediation through both mitogen-activated protein kinase and NF-kappaB signaling pathways in macrophages. 929 54

We investigated the effect of the p38 kinase inhibitor SB 203580 on airway inflammation induced by aerosolized lipopolysaccharide (LPS) in male Wistar rats. SB 203580 significantly inhibited (ED(50)=15.8 mg kg(-1)) plasma levels of TNF-alpha in rats challenged with LPS (1.5 mg kg(-1), i.p.). Aerosolized LPS induced a peak in TNF-alpha levels and the initiation of a neutrophilic response in bronchoalveolar lavage (BAL) fluid at the 2 h time point. Furthermore, the 4 h time point was associated with the peak in IL-1beta levels and the initial plateau of neutrophilia observed in the BAL fluid. SB 203580 (100 mg kg(-1)), had no effect on peak TNF-alpha levels or the associated neutrophilia in the BAL. Interestingly, the PDE 4 inhibitor RP 73401 (100 mg kg(-1)) significantly reduced both TNF-alpha levels and neutrophilic inflammation. However, the BAL fluid from rats pre-treated with either compound significantly inhibited TNF-alpha release from cultured human monocytes 18 h after LPS treatment (83.6 and 44.5% inhibition, respectively). Alternatively, SB 203580 (100 mg kg(-1)) produced dose-related inhibition of BAL IL-1beta levels (67.5% inhibition, P<0.01) and BAL neutrophilia (45.9% inhibition, P<0.01) 4 h after LPS challenge. P38 protein was present in lung tissue and the level of expression was not affected by LPS treatment. P38 kinase appears to be involved in the release of IL-1beta and the sustained neutrophilic response in the BAL fluid. This data may suggest a role for p38 inhibitors in the treatment of airway inflammatory diseases in which neutrophilia is a feature of the lung pathology.
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PMID:Role of p38 MAP kinase in LPS-induced airway inflammation in the rat. 1130 43

ONO-4007 is a new synthetic lipid A derivative with low endotoxic activities. We have reported that ONO-4007 could be a new bio-logical response modifier for the treatment of tumor necrosis factor (TNF)-alpha-sensitive tumors. In this study, we confirmed that ONO-4007 activated a murine macrophage cell line, RAW264.7, and that the activated RAW264.7 cells produced TNF-alpha. RAW264.7 cells stimulated for less than 15 min with ONO-4007 (40 g/ml) did not produce TNF-alpha (less than 4 U/ml). However, 24 h stimulation with ONO-4007 induced TNF-alpha production (more than 256 U/ml) in RAW264.7 cells. Although P38 in mitogen-activated protein kinase of the RAW264.7 cells was not tyrosine phosphorylated by ONO-4007 stimulation, ERK1 of the RAW264.7 cells was tyrosine phosphorylated for 5-15 min by ONO-4007 stimulation. Tyrosine phosphorylation of ERK1 decreased gradually from 15 min after stimulation and almost disappeared 60 min after stimulation. These findings indicate that ONO-4007 stimulates RAW264.7 cells immediately and induces tyrosine phosphorylation of ERK1 in the RAW264.7 cells for 5-15 min. These data suggest that the signal transduction pathway of ONO-4007 may be similar to that of lipopolysaccharide.
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PMID:A signaling pathway by a new synthetic lipid A analog, ONO-4007, in RAW264.7 cells. 1243 41

P38 mitogen-activated protein kinase (MAPK) is an important component of intracellular signaling cascades that initiate various inflammatory cellular responses. To determine the role of p38 MAPK in the procoagulant response to lipopolysaccharide (LPS), 24 healthy subjects were exposed to an intravenous dose of LPS (4 ng/kg), preceded 3 hours earlier by orally administered 600 or 50 mg BIRB 796 BS (a specific p38 MAPK inhibitor), or placebo. The 600-mg dose of BIRB 796 BS strongly inhibited LPS-induced coagulation activation, as measured by plasma concentrations of the prothrombin fragment F1 + 2. BIRB 796 BS also dose dependently attenuated the activation and subsequent inhibition of the fibrinolytic system (plasma tissue-type plasminogen activator, plasmin-alpha2-antiplasmin complexes, and plasminogen activator inhibitor type 1) and endothelial cell activation (plasma soluble E-selectin and von Willebrand factor). Activation of p38 MAPK plays an important role in the procoagulant and endothelial cell response after in vivo exposure to LPS.
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PMID:Inhibition of coagulation, fibrinolysis, and endothelial cell activation by a p38 mitogen-activated protein kinase inhibitor during human endotoxemia. 1257 15

The current study characterizes the mechanism by which mercury, a toxic metal, induces death in murine macrophages. The cytotoxic EC(50) of mercury ranged from 62.7 to 81.1 microM by various assays in J774A.1 cultures; accordingly, we employed 70 microM of mercuric chloride in most experiments. Mercury-induced intracellular calcium modulated reactive oxygen species (ROS) production, which resulted in both cell apoptosis and necrosis indicated by annexin V binding and caspase-3 activity, and propidium-iodide binding. Calcium antagonists abolished ROS production. Mercury stimulated p38 mitogen-activated protein kinase (MAPK) and additively stimulated lipopolysaccharide-activated p38. Mercury-activated p38 was decreased by pretreatment of cells with antioxidants, N-acetylcysteine (NAC) and silymarin, indicating that mercury-induced ROS were involved in p38 activation. Mercury increased the expression of tumor necrosis factor alpha (TNFalpha); antioxidants and a specific p38 inhibitor decreased this effect. Pretreatment with antioxidants, p38 inhibitor, and anti-TNFalpha antibody decreased mercury-induced necrosis; however, anti-TNFalpha antibody did not decrease mercury-induced apoptosis. Results suggest that mercury-induced macrophage death is a mix of apoptosis and necrosis employing different pathways. P38-mediated caspase activation regulates mercury-induced apoptosis and p38-mediated TNFalpha regulates necrosis in these cells. Calcium regulates ROS production and mercury-induced ROS modulate downstream p38 that regulates both apoptosis and necrosis.
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PMID:Mercury-induced apoptosis and necrosis in murine macrophages: role of calcium-induced reactive oxygen species and p38 mitogen-activated protein kinase signaling. 1505 Apr 7

Leptin is now recognized as a proinflammatory cytokine and thought to be a progressive factor for non-alcoholic steatohepatitis (NASH). Here we showed the effects of leptin on the production of TNF-alpha (tumor necrosis factor-alpha) by Kupffer cells (KCs) with signal transduction. Leptin enhanced TNF-alpha production accompanied by a dose-dependent increase of MAPK activity in lipopolysaccharide (LPS)-stimulated KCs. SB203580 and JNK inhibitor I, specific inhibitors of P38 and JNK, inhibited TNF-alpha production in KCs but PD98059, an inhibitor of the ERK pathway, did not affect TNF-alpha production by KCs. Recombinant constitutively active adenovirus (Ad)-MKK6 and-MKK7 increased TNF-alpha production in KCs with activation of P38 and JNK without any change by Ad-MEK1 delivery. On the other hand, KCs isolated from the Zucker rat (fa/fa), a leptin receptor-deficient rat, showed reduced production of TNF-alpha on stimulation with LPS. The delivery of Ad-MKK6 and-MKK7, but not Ad-MEK1, increased TNF-alpha production in KCs of Zucker rats with activation of P38 and JNK. Addition of leptin to normal rats increased LPS-induced hepatic TNF-alpha production in vivo and leptin receptor-deficient Zucker rats showed reduced hepatic TNF-alpha production on addition of LPS in vivo. These findings indicate that P38 and JNK pathways are involved in the signal transduction of leptin enhancement of LPS-induced TNF-alpha production.
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PMID:Leptin enhances TNF-alpha production via p38 and JNK MAPK in LPS-stimulated Kupffer cells. 1597 53

Mitogen-activated protein kinases (MAPKs) are important mediators of cytokine expression and are critically involved in the immune response. The lipopolysaccharide (LPS) of gram-negative bacteria induces the expression of cytokines and proinflammatory genes via the toll-like receptor 4 (TLR4) signaling pathway in diverse cell types. In vivo, Schwann cells (SCs) at the site of injury may also produce tumor necrosis factor-- alpha (TNF-alpha). However, the precise mechanisms of TNF-alpha synthesis are still not clear. The purpose of the present study was to elucidate the underlying molecular mechanisms in the cultured SCs for its ability to activate the MAPKs and TNF-alpha gene, in response to LPS. Using enzyme-linked immunosorbent assay (ELISA), it was confirmed that treatment with LPS stimulated the synthesis of TNF-alpha in a concentration- and time-dependent manner. Intracellular location of TNF-alpha was detected under confocal microscope. Moreover, LPS activated extracellular signal-regulated kinase (ERK1/2), P38 and stress activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) and induced their phosphorylation. LPS-elicited SCs TNF-alpha production was also drastically suppressed by PD98059 (ERK inhibitor), SB202190 (P38 inhibitor), or SP600125 (SAPK/JNK inhibitor). Additionally, the expression of CD14 and TLR4 was examined by RT-PCR. It was demonstrated that the expression of CD14, TLR4 was crucial for the SCs responses to LPS. In conclusion, the results provide novel mechanisms for the response of SCs to LPS stimulation, through MAPKs signaling pathways.
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PMID:Induction of TNF-alpha by LPS in Schwann cell is regulated by MAPK activation signals. 1790 45

Oxidative stress and inflammation are related to several chronic diseases including cancer and atherosclerosis. Hibiscus sabdariffa Linnaeus has been found to possess antioxidant effects. In this study, polyphenols extracted from Hibiscus sabdariffa L. (HPE) were used to detect anti-inflammatory effects on nitrite and prostaglandin E(2) (PGE(2)) in lipopolysaccharide (LPS) treated RAW264.7 cells. Sequentially, an animal model examination was performed to confirm the effects of HPE on LPS-induced hepatic inflammation. The results showed that HPE reduced 94.6% of xanthine oxidase activity in vitro, and decreased nitrite and PGE(2) secretions in LPS-induced cells. In LPS-treated rats, HPE significantly decreased the serum levels of alanine and aspartate aminotransferase. In the liver, lipid peroxidation and liver lesions decreased, and catalase activity and glutathione increased. The study also revealed that down-regulation of cyclooxygenase-2 (COX-2), p-c-Jun N-terminal kinase (p-JNK) and p-P38 might have been involved. In sum, this study found an anti-inflammatory potency of HPE both in vitro and in vivo.
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PMID:Polyphenols extracted from Hibiscus sabdariffa L. inhibited lipopolysaccharide-induced inflammation by improving antioxidative conditions and regulating cyclooxygenase-2 expression. 1920 85

Adenosine is an endogenous nucleoside that has potent receptor-mediated immunomodulatory effects on macrophage/monocyte function. In this study, we determined the effects of an adenosine A(2A) receptor agonist, ATL313, on the expression of mRNAs for four pro-inflammatory mediators, IL-1beta, IL-8, COX-2, and TNF-alpha, and the mRNA and protein for the anti-inflammatory cytokine, IL-10 in equine monocytes incubated with lipopolysaccharide (LPS). The results indicate that ATL313 significantly reduces LPS-induced expression of COX-2 and TNF-alpha, enhances the expression of IL-10 and IL-8, but does not alter the expression of IL-1beta. These effects of ATL313 were reversed by co-incubation with the selective adenosine A(2A) antagonist ZM241385, and were mimicked by the cAMP analogue dibutyryl cAMP. These differential effects of adenosine A(2A) receptor activation were in contrast to those obtained using the P38 MAPK inhibitor, SB203580, which nearly abolished all LPS-induced changes in mRNA expression as well as the production of TNF-alpha protein. These findings, which indicate that adenosine A(2A) receptor activation modulates the transcription of several, but not all, pro-inflammatory mediators and exerts a synergistic effect on the induction of at least one anti-inflammatory cytokine, suggest that selective adenosine A(2A) agonists may reduce the early pro-inflammatory effects of endotoxemia in horses.
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PMID:Differential modulation of lipopolysaccharide-induced expression of inflammatory genes in equine monocytes through activation of adenosine A2A receptors. 1976 23

It has been postulated that at least part of the loss of cognitive function in aging may be the result of deficits in Ca(2+) recovery (CAR) and increased oxidative/inflammatory (OX/INF) stress signaling. However, previous research showed that aged animals supplemented with blueberry (BB) extract showed fewer deficits in CAR, as well as motor and cognitive functional deficits. A recent subsequent experiment has shown that DA- or Abeta(42)-induced deficits in CAR in primary hippocampal neuronal cells (HNC) were antagonized by BB extract, and (OX/INF) signaling was reduced. The present experiments assessed the most effective BB polyphenol fraction that could protect against OX/INF-induced deficits in CAR, ROS generation, or viability. HNCs treated with BB extract, BB fractions (e.g., proanthocyanidin, PAC), or control medium were exposed to dopamine (DA, 0.1 mM), amyloid beta (Abeta(42), 25 muM) or lipopolysaccharide (LPS, 1 microg/mL). The results indicated that the degree of protection against deficits in CAR varied as a function of the stressor and was generally greater against Abeta(42) and LPS than DA. The whole BB, anthocyanin (ANTH), and PRE-C18 fractions offered the greatest protection, whereas chlorogenic acid offered the lowest protection. Protective capabilities of the various fractions against ROS depended upon the stressor, where the BB extract and the combined PAC (high and low molecular weight) fraction offered the best protection against LPS and Abeta(42) but were less effective against DA-induced ROS. The high and low molecular weight PACs and the ANTH fractions enhanced ROS production regardless of the stressor used, and this reflected increased activation of stress signals (e.g., P38 MAPK). The viability data indicated that the whole BB and combined PAC fraction showed greater protective effects against the stressors than the more fractionated polyphenolic components. Thus, these results suggest that, except for a few instances, the lesser the polyphenolic fractionation, the greater the effects, especially with respect to prevention of ROS and stress signal generation and viability.
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PMID:Differential protection among fractionated blueberry polyphenolic families against DA-, Abeta(42)- and LPS-induced decrements in Ca(2+) buffering in primary hippocampal cells. 2059 78


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