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)

Phospholipase A2 activity in the postnuclear supernatant of lymphocytes has been studied by measuring 14C arachidonate released from labelled phosphatidyl ethanolamine (PE) and phosphatidyl choline (PC) as exogenous substrates. The pH optimum was 7.5-9.0 for PE and 9.0 for PC. Phospholipase A2 was not detected in the presence of 2 mM EGTA. It was optimal with the millimolar calcium concentrations and higher towards PE. Preincubation of lymphocytes with 0.5 M ionophore A-23187 was followed by 2.4 fold stimulation of the phospholipase activity. A stimulatory effect was observed after preincubation of cells with 10 micrograms/ml of phytohemagglutinin, lipopolysaccharide, concanavalin A; it decreased as: lipopolysaccharide greater than phytohemagglutinin greater than concanavalin A. The results obtained have suggested the possibility of existence of different forms of phospholipase A2 in the spleen lymphocytes and participation of the enzyme in the early signalling events.
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PMID:[Phospholipase A2 from rat spleen lymphocytes hydrolyzing arachidonoyl-phospholipids]. 181 83

In the present study, we sought to identify the T cell-replacing factor which selectively induces IgG2b antibody formation in lipopolysaccharide-activated mouse spleen cells in vitro and in vivo, and which is present in the synovial fluid (SF) of rheumatoid arthritis (RA) patients. The protein A plaque assay was used to measure IgM, IgG1, IgG2b, and IgG3 plaque-forming cells. An enzyme-linked immunosorbent assay was used to measure interleukin-6 (IL-6) levels in RA SF. We found that IgG2b induction by RA SF is not caused by IL-6, IL-1, or any other inflammatory cytokines or mediators, such as transforming growth factor beta, platelet-derived growth factor, nerve growth factor, fibroblast growth factor, epidermal growth factor, elastase, collagenase, and phospholipase A2. IgG2b-inducing factor in RA SF has unique biological properties compared with those of the interleukins and inflammatory mediators known to be present in RA SF.
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PMID:Relationship between IgG2b-inducing activity in rheumatoid arthritis synovial fluid and other well-known cytokines and inflammatory mediators. 195 23

The specific activity of phospholipase A2 (PLA2) in the liver homogenate was elevated 1.7-fold in bacillus Calmette-Guerin (BCG)-treated rats, 1.6-fold in lipopolysaccharide (LPS)-treated rats, and 2.4-fold in BCG-infected rats treated with LPS, compared with that of control rats. These increased activities were almost completely inhibited by the antibody directed against rat splenic group II PLA2 (PLA2M) but not by anti-pancreatic PLA2 antibody. The results of immunoblot analysis confirmed that the PLA2 immunochemically related to the group II enzyme was induced by treatment with BCG and/or LPS. The anti-PLA2M antibody-inhibitable PLA2 activity per a single cell was elevated not only in nonparenchymal cell fraction but also in hepatocyte fraction, as in the case of whole liver. On the contrary, the PLA2 concentration and its specific activity did not change by the same treatment both in spleen homogenate and in isolated spleen cell fractions although a 3-fold increase in spleen mass occurred by BCG treatment. These results suggested that a tissue-specific mechanism of the PLA2 induction by these inflammatory mediators may operate in liver.
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PMID:Induction of group II-like phospholipase A2 by lipopolysaccharide in the liver of BCG-primed rat. 199 76

Inflammatory factors such as tumor necrosis factor (TNF), interleukin 1 (IL-1), and lipopolysaccharide (LPS) greatly enhance the expression of group II phospholipase A2 (PLA2-II) mRNA, leading to increased secretion of PLA2-II enzyme from rat-cultured astrocytes. The potent antiinflammatory agent dexamethasone suppressed the PLA2-II expression induced by LPS. In vivo studies also demonstrated that the level of PLA2-II mRNA in the brain increased with intravenous injection of LPS. These results suggest that PLA2-II in the brain plays important roles in the inflammatory response. Agents which increase intracellular cAMP concentration did not stimulate PLA2-II expression by themselves but selectively enhanced TNF-induced PLA2-II expression about 5-fold. Phorbol ester, a well known protein kinase C activator, increased the PLA2-II expression. H-7, a protein kinase C inhibitor, inhibited the LPS-induced PLA2-II expression, but did not inhibit the TNF-induced one. Therefore, we conclude that the TNF-activated pathway differs from the LPS-activated one: the former is enhanced by cAMP and the latter involves protein kinase C.
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PMID:Inflammatory factors stimulate expression of group II phospholipase A2 in rat cultured astrocytes. Two distinct pathways of the gene expression. 203 82

Bovine pulmonary artery endothelial cells (BPAEC) were labeled with 3H-arachidonic acid. Exposure of the labeled BPAEC to Pasteurella haemolytica lipopolysaccharide (LPS) resulted in a time- and dose-dependent release of radioactivity. The release was inhibited by 5 mM indomethacin, but inhibition was not caused by less than or equal to 500 microM indomethacin or hydrocortisone, which suggests that the release was caused primarily by a mechanism other than cyclooxygenase or phospholipase A2 metabolism of arachidonic acid. Pasteurella haemolytica LPS also caused increased adherence of bovine neutrophils to BPAEC through independent effects on both cell types. The increased adherence was inhibited by treatment of either cell type with cycloheximide or actinomycin D prior to LPS exposure, indicating that de novo protein synthesis was required in both cell types to promote the LPS-induced adherence. Lipopolysaccharide may be an important factor in neutrophil-mediated effects in pneumonic pasteurellosis by causing increased neutrophil adherence and, thus, the vascular sequestration of neutrophils. Together, these experiments provide additional evidence for the involvement of LPS in pneumonic pasteurellosis. Moreover, they provide evidence of LPS-induced endothelial activation, which could have broad ramifications in the inflammatory and immune responses of pneumonic pasteurellosis.
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PMID:Pasteurella haemolytica lipopolysaccharide-induced arachidonic acid release from and neutrophil adherence to bovine pulmonary artery endothelial cells. 212 78

The mechanism(s) involved in the generation of free radicals in human leukocytes by phorbol myristate acetate (PMA), formyl-methionyl-leucyl-phenylalanine (FMP), lipopolysaccharide (LPS), arachidonic acid (AA), and recombinant-tumor necrosis factor-1-alpha (r-TNF-1 alpha) was investigated. Calmodulin antagonists, chlorpromazine and trifluoperazine, inhibited free radical generation in human leukocytes by these stimulants. Dexamethosone, an inhibitor of phospholipase A2, could also block free radical generation in human leukocytes induced by r-TNF 1 alpha. PMA, FMP, LPS and TNF can activate phospholipase A2 and induce the release of AA from the cell membrane lipid pool. AA induced free radical generation in human leukocytes can be inhibited by calmodulin antagonists. Hence, it is likely that calmodulin dependent events play a crucial role in the generation of free radicals by human leukocytes in response to various stimulants including TNF.
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PMID:Stimulation of free radical generation in human leukocytes by various agents including tumor necrosis factor is a calmodulin dependent process. 215 20

The mechanism(s) involved in the generation of free radicals in human leukocytes by cis-unsaturated fatty acids, gamma-linolenic acid (GLA), and arachidonic acid (AA), was investigated. Calmodulin antagonists, chlorpromazine and trifluoperazine, inhibited free radical generation by human leukocytes in vitro induced by GLA, AA PMA (Phorbol myristate acetate), formyl-methionyl-leucyl-phenylalanine (FMLP) and lipopolysaccharide (LPS). On the other hand, chloroquine, a phospholipase A2 inhibitor, and colchicine, a microtubule disrupting agent, were without any effect. When sub-optimal concentrations of GLA and AA were added together, leukocytes showed an additive effect on free radical generation. These results indicate that Calmodulin dependent event(s) play a significant role in the generation of free radicals by human leukocytes.
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PMID:Free radical generation in human leukocytes by CIS-unsaturated fatty acids is a calmodulin dependent process. 216 83

Mouse peritoneal macrophages respond to activators of protein kinase C and to zymosan particles and calcium ionophore by rapid enhancement of a phospholipase A pathway and mobilization of arachidonic acid. The pattern of protein phosphorylation induced in these cells by 4 beta-phorbol 12-myristate 13-acetate (PMA), 1,2-dioctanoyl-sn-glycerol, exogenous phospholipase C and by zymosan and ionophore A23187 was found to be virtually identical. The time course of phosphorylation differed among the phosphoprotein bands and in only some of those identified (i.e., those of 45 and 65 kDa) was the phosphorylation sufficiently rapid to be involved in the activation of the phospholipase A pathway. Phosphorylation of lipocortin I or II could not be detected. Down-regulation of kinase C by a 24-h pretreatment with PMA resulted in extensive inhibition of both protein phosphorylation and the mobilization of arachidonic acid in response to PMA or dioctanoylglycerol. The phosphorylation of the 45 kDa protein in response to zymosan and A23187 was also inhibited by pretreatment with PMA, while only arachidonic acid release induced by zymosan was inhibited by this pretreatment. Depletion of intracellular calcium had little effect on kinase C-dependent phosphorylation, although arachidonic acid mobilization is severely inhibited under these conditions. Bacterial lipopolysaccharide and lipid A induced a phosphorylation pattern different from that induced by PMA, and down-regulation of protein kinase C did not affect lipopolysaccharide-induced protein phosphorylation. The results indicate (i) that protein kinase C plays a critical role also in zymosan-induced activation of the phospholipase A pathway mobilizing arachidonic acid; (ii) that such activation requires calcium at some step distal to kinase C-mediated phosphorylation and (iii) that phosphorylation of lipocortins does not explain the kinase C-dependent activation.
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PMID:A role for protein kinase C-mediated phosphorylation in the mobilization of arachidonic acid in mouse macrophages. 249 91

To characterize the mechanism of the anorexia during infection, we investigated the effect of E. coli lipopolysaccharide (LPS) on feeding in rats under various conditions: LPS (125, 100, 75, and 50 micrograms/kg body weight = b. wt.) injected intraperitoneally (IP) reduced food intake by decreasing meal frequency without affecting meal size. The Ca++-channel blocker verapamil (5 mg/kg b. wt., IP) or the antipyretic and antiphlogistic drug indomethacin (2.5 mg/kg b. wt., IP), but not combined alpha- and beta-adrenergic receptor blockade by IP phentolamine plus propranolol (500 micrograms/kg b. wt., each) attenuated the anorectic effect of LPS (125 or 100 micrograms/kg b. wt.). The results suggest that a phospholipase A2-sensitive mechanism contributes to the anorexia during injection.
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PMID:Verapamil and indomethacin attenuate endotoxin-induced anorexia. 269 50

The interaction of lipopolysaccharide toxin (LPS) with isolated washed human blood platelets has been studied. LPS was found to induce the rapid (1-2 min) and marked (15-20%) breakdown of mono- and polyphosphoinositides and formation of significant amounts of diacylglycerols (ca. 20%). However TxB2 biosynthesis from endogenous 14C-arachidonic acid was stimulated by LPS incubation only by ca. 20%. Phosphatidylcholine and phosphatidylethanolamine were also hydrolysed by ca. 8 and 12%, respectively, presumably via the activation of endogenous phospholipase A2. Besides, LPS caused the decreasing of the lipid fluidity of a platelet plasma membrane as was shown by ESR spectroscopy using doxylstearic acid probes. All these changes by LPS induce no aggregation of platelets. It is concluded that an enhancement of a phosphoinositide cycle is not a possibly necessary and sufficient condition for a platelet aggregation.
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PMID:[Phosphoinositide breakdown and diacyl glycerin formation in human thrombocytes as affected by a lipopolysaccharide toxin]. 283 17


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