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)

It is known that murine macrophages produce nitric oxide (NO) when stimulated with lipopolysaccharide (LPS) or interferon-gamma (IFN-gamma), and NO mediates the tumoricidal activity of activated macrophages. The present study was designed to investigate whether the intercellular adhesion is necessary for activated rat alveolar macrophages to exert the full cytotoxic effects. Rat alveolar macrophages produced NO dose dependently in response to either LPS or IFN-gamma, and caused DNA fragmentation in rat type II pneumocytes transformed with SV40 (SV40T2). Chemically produced NO also caused the DNA fragmentation and viability loss in SV40T2, and both of them were inhibited by a NO radical scavenger. The cytotoxicity of activated macrophages was reduced by NG-monomethyl-L-arginine, a competitive nitric synthase inhibitor, and neither superoxide dismutase nor catalase modulated the cytotoxicity. Although alveolar macrophages stimulated with either LPS or IFN-gamma caused DNA fragmentation of SV40T2, only LPS increased the intercellular adherence between macrophages and SV40T2. The intercellular adhesion was reduced by both anti-CD18 and anti-CD11a. However, those antibodies did not affect the cytotoxicity of LPS-stimulated macrophages. These results clearly indicate that NO-mediated cytotoxicity is caused predominantly by diffusion of NO, and the beta 2 integrin-mediated intercellular adhesion does not play an important role, if any, in activated macrophage-mediated cytotoxic effects on SV40T2.
 ...
PMID:Nitric oxide-mediated cytotoxic effects of alveolar macrophages on transformed lung epithelial cells are independent of the beta 2 integrin-mediated intercellular adhesion. 953 25

Sepsis is believed to increase the risk of bilirubin brain toxicity, but the mechanism is not known. Adult male Sprague-Dawley rats were injected intraperitoneally with either 20 mg/kg Escherichia coli lipopolysaccharide, approximately 5 x 10(9)/kg CFU Listeria monocytogenes or vehicle 48 h prior to sacrifice. Rats were killed with an intraperitoneal injection of pentobarbital. Mitochondrial membrane fractions were produced by homogenization of the brains and differential centrifugation in 0.32 M sucrose. The mitochondrial pellet was resuspended in distilled water and sonicated to rupture the mitochondria. The protein concentration of the suspension was standardized to 2.5 mg/ml. Bilirubin oxidation was assayed in a pH 8.2, 0.1 M barbital buffer containing 10 microM bilirubin, 5 mM EDTA, and 500 U/ml catalase. Optical density was measured at 440 nm before and after a 60-min incubation at 37.5 degrees C. There were no differences between the control, endotoxemic, and septic groups as far as the ability of brain mitochondrial membranes to oxidize bilirubin (bilirubin oxidation rate: 289 +/- 11 vs. 295 +/- 9 vs. 296 +/- 12 pmol/min/mg protein, mean +/- SD). We conclude that endotoxemia or sepsis do not change the ability of brain mitochondrial membranes to oxidize bilirubin. If sepsis truly increases the risk of bilirubin encephalopathy in neonatal jaundice, this is likely to involve other mechanisms.
 ...
PMID:Effects of endotoxemia and sepsis on bilirubin oxidation by rat brain mitochondrial membranes. 957 65

During the innate immune response, excessive release of reactive oxygen species (ROS) from sequestered phagocytes and activated resident macrophages represents the predominant component of oxidative stress in the liver and other tissues. The consequence of oxidative stress is determined by the status and adaptive changes of antioxidant pathways. In this review, we present evidence that the synchronized response of hepatic sinusoidal endothelial cells, the primary sites of phagocyte attachment, plays an important role in defense against phagocyte-derived ROS. An essential component of the metabolic adaptation of hepatic sinusoidal cells to lipopolysaccharide (LPS)-induced oxidative stress is the stimulated expression of glucose-6-phosphate dehydrogenase (G6PD), the key enzyme of the pentose cycle (hexose monophosphate shunt, HMS). All major ROS-metabolic enzymes, i.e., glutathione peroxidase, glutathione reductase, catalase, superoxide dismutases, NADPH oxidase, and nitric oxide synthase, directly or indirectly depend on NADPH, which is produced in the HMS in these cells. The functional significance of up-regulated HMS within a particular cell type depends on the accompanying adaptive changes in ROS-metabolizing enzymes. In LPS-activated Kupffer cells, the elevated expression of glucose transporter GLUT1 and G6PD mainly serves primed production of superoxide anion, hydrogen peroxide, and nitric oxide. In sinusoidal endothelial cells, the LPS-induced response pattern of glucose- and ROS-metabolizing enzymes results in elevated ROS detoxifying capacity. The described studies also suggest the existence of an intercellular oxidant balance between pro-oxidant Kupffer cells and antioxidant endothelial cells in the hepatic micro-environment. Maintenance of the intercellular oxidant/antioxidant balance between phagocytes and endothelial cells may represent an important mechanism protecting the hepatic parenchyma against exogenous oxidative stress during the inflammatory response.
 ...
PMID:Endotoxemia, pentose cycle, and the oxidant/antioxidant balance in the hepatic sinusoid. 958 96

To evaluate occurrence of oxidative stress in circulating blood, we developed standard methods to assess (1) granulocytes status as a source of reactive oxygen species (ROS) and (2) lipid peroxidation (LPO). A simplified and highly sensitive assay was developed by utilizing the chemiluminescence (CL) from luminol oxidized by ROS. 1. The CL, from 300 microliters medium containing 1% blood, 10 micrograms/ml luminol and 0.025 microgram/ml phorbol myristate acetate, well reflected the primed granulocyte status induced by in vitro contact with lipopolysaccharide (LPS). This CL was weakened slightly by superoxide dismutase and catalase, but markedly decreased by sodium azide. 2. We determined the optimal conditions for the t-butyl hydroperoxide (t-BuOOH)-stimulated CL method to evaluate plasma LPO in experiments on rat plasma added with phosphatidylethanolamine hydroperoxide (PEOOH). The CL from 300 microliters medium containing 6.67% plasma. 10 micrograms/ml luminol and 5 mumol/ml t-BuOOH was proportional to the added PEOOH amount. The integrated CL of the plasma with 0-60 nmol of PEOOH gave values of 8.280-14.213 x 10(6) counts/60 min/tube. 3. Only 100 microliters of freshly drawn blood was enough for the two CL methods to detect the generation of ROS and the occurrence of LPO. These CL methods enabled the determination of the time course of oxidative stress occurrence in circulating blood of rats treated with 5 mg/kg LPS, i.p.
 ...
PMID:[Assay for oxidative stress injury by detection of luminol-enhanced chemiluminescence in a freshly obtained blood sample: a study to follow the time course of oxidative injury]. 958 81

Bacterial lipopolysaccharide (LPS) in the presence of interferon gamma (IFNgamma) stimulates the synthesis of the cationic amino acid transporter 2B (CAT-2B) and inducible nitric oxide synthetase (iNOS) in RAW264 macrophages, which are thought to underlie the increased rate of arginine uptake into these cells and its conversion to nitric oxide, respectively. Here I demonstrate that the LPS- and IFNgamma-induced increase in arginine uptake into RAW264 cells is partially suppressed in the presence of PD 98059, partially suppressed in the presence of SB 203580, and completely inhibited by both drugs. In contrast, the LPS- and IFNgamma-induced synthesis of CAT-2B mRNA and iNOS protein is unaffected by PD 98059 and SB 203580. The results indicate that the MAPK/ERK and SAPK2/p38 cascades are both rate-limiting for LPS- and IFNgamma-stimulated arginine uptake, but not for iNOS synthesis. They also suggest that PD 98059 and SB 203580 suppress CAT-2B synthesis at a post-transcriptional level.
 ...
PMID:Role of MAP kinase cascades in inducing arginine transporters and nitric oxide synthetase in RAW264 macrophages. 966 26

The role of the inflammatory cytokine interleukin 1beta (IL-1beta) as potent agonist of the PMN respiratory burst signal transduction cascade has been described. We hypothesized that this phenomenon is self-limiting and that polymorphonuclear leukocyte (PMN)-derived reactive oxygen intermediates (ROI) might provide feedback regulation on the IL-1beta surface receptor (IL-1betaR)-G-protein-effector enzyme transducing tripartite complex that ultimately leads to NADPH oxidase activation. Therefore, we separately assessed either baseline or IL-1beta-induced activation of each member of the IL-1betaR-G-protein-phospholipase D (PLD) or IL-1betaR-G-protein-phospholipase C (PLC) signaling systems in the presence or absence of one of several specific ROI scavengers/antioxidants. Purified human PMN were lipopolysaccharide primed, adhered for 2 h, and stimulated with 100 ng/mL IL-1beta with or without 1% v/v dimethyl sulfoxide, 10 mM NaN3, 30 mM L-alanine, 200 U catalase, or 300 U superoxide dismutase (SOD). To validate the use of these antioxidants, the production of O2-, H2O2, hypochlorous acid, or myeloperoxidase (MPO) in the employed experimental model was confirmed in a separate set of experiments. The expression of IL-1betaR type I or II was assessed by binding with corresponding 125I-labeled monoclonal antibodies and corrected for nonspecific binding. PLD activation was assessed by measuring phosphatidyl ethanol formation in the presence of ethanol. PLC activation was determined by quantitative measurement of diacylglycerol. The level of Galpha stimulatory and inhibitory subunits was assessed by Western blotting. IL-1betaR type I expression was significantly up-regulated in the presence of catalase and SOD. PLD activation was increased by dimethyl sulfoxide and NaN3, and PLC activation was up-regulated by NaN3, L-alanine, SOD, and catalase. After 5 min of stimulation with IL-1beta, Gialpha expression was significantly down-regulated by NaN3 and SOD, whereas SOD had an up-regulating effect on the expression of Gs alpha. Increasing concentrations of externally added authentic MPO progressively down-regulated both PLD and PLC activity. Thus, PMN-derived ROI, in addition to their role as antibacterial/fungal agents, serve as second messengers in IL-1beta signal transduction, with MPO having the most ubiquitous role as a modulator of PMN second messenger pathways.
 ...
PMID:The role of neutrophil-derived oxidants as second messengers in interleukin 1beta-stimulated cells. 968 92

Mating pair stabilization occurs during conjugative DNA transfer whereby the donor and recipient cells form a tight junction which requires pili as well as TraN and TraG in the donor cell. The role of the outer membrane protein, TraN, during conjugative transfer was examined by introduction of a chloramphenicol resistance cassette into the traN gene on an F plasmid derivative, pOX38, to produce pOX38N1::CAT. pOX38N1::CAT was greatly reduced in its ability to transfer DNA, indicating that TraN plays a greater role in conjugation than previously thought. F and R100-1 traN were capable of complementing pOX38N1::CAT transfer equally well when wild-type recipients were used. F traN, but not R100-1 traN, supported a much lower level of transfer when there was an ompA mutation or lipopolysaccharide (LPS) deficiency in the recipient cell, suggesting receptor specificity. The R100-1 traN gene was sequenced, and the gene product was found to exhibit 82.3% overall similarity with F TraN. The differences were mainly located within a central region of the proteins (amino acids 162 to 333 of F and 162 to 348 of R100-1). Deletion analysis of F traN suggested that this central portion might be responsible for the receptor specificity displayed by TraN. TraN was not responsible for TraT-dependent surface exclusion. Thus, TraN, and not the F pilus, appears to interact with OmpA and LPS moieties during conjugation, resulting in mating pair stabilization, the first step in efficient mobilization of DNA.
 ...
PMID:Genetic analysis of the role of the transfer gene, traN, of the F and R100-1 plasmids in mating pair stabilization during conjugation. 969 48

We studied, using organotypic hippocampal slices in culture, the role of pro-inflammatory cytokines, oxygen radicals and nitric oxide in neuronal death induced either by endotoxic insult [interferon (IFN) gamma, 24 h followed by lipopolysaccharide, 24 h] or by glutamate receptor-mediated excitotoxic insult. We demonstrated that neuronal death induced by endotoxic insult was absolutely dependent on the synthesis of tumour necrosis factor alpha (TNF-alpha). Indeed, TNF-alpha antibodies and SB203580, an inhibitor of p38 stress kinase known to block TNF-alpha and other cytokine synthesis, completely protected neurons from the endotoxic insult. Inhibiting oxygen radical and nitric oxide productions also reduced the endotoxic shock. We also showed that after priming the cultures with IFN-gamma, TNF-alpha was unable to induce neuronal death unless oxygen-free radicals were exogenously provided. In contrast, although glutamate receptor-induced excitotoxicity was associated with a low TNF-alpha synthesis and a modest activation of p38 stress kinase, neither TNF-alpha antibodies nor SB203580 were able to decrease excitotoxic neuronal insult. We did not reduce glutamate receptor-induced neuronal death with superoxide dismutase plus catalase. In conclusion, although inflammation follows glutamate receptor-mediated neurotoxicity, the mechanisms by which an endotoxic insult triggers neuronal death are different from those involved in excitotoxicity.
 ...
PMID:The neuronal death induced by endotoxic shock but not that induced by excitatory amino acids requires TNF-alpha. 978 5

Kupffer cells and other macrophages play an important role in pathogenesis of toxicants in the liver. The aim of this study was to evaluate the effect of macrophages on hepatocyte production of nitric oxide (NO), which has been previously reported to be protective toward oxidative stress induced in primary rat hepatocytes. For this purpose, RAW 264.7 macrophages were added to primary rat hepatocytes at various ratios between macrophages and hepatocytes. These cocultures were supplemented with lipopolysaccharide (LPS) and interferon gamma (IFN-gamma) for 23 hours to induce NO synthase and trigger NO production. NO production was followed by quantification of nitrites in culture medium and dinitrosyl iron complexes (DNIC) in intact hepatocytes after separation from macrophages. In cocultured hepatocytes incubated with LPS and IFN-gamma, DNIC and nitrite levels decreased compared with those observed in hepatocytes cultured without macrophages in the same conditions. Moreover, inhibition of NO production in hepatocyte cocultures was macrophage-number-dependent. Macrophage-conditioned medium also inhibited NO production in hepatocytes, suggesting that the effect of macrophages was mediated by soluble factors. Among the soluble factors known to decrease NO levels are some cytokines, growth factors, reactive oxygen species, and prostaglandins. Ultrafiltration of macrophage-conditioned medium through a 500-d membrane to rule out higher-molecular-weight molecules, such as anti-inflammatory cytokines and growth factors, failed to restore NO production. In the same way, the use of superoxide dismutase (SOD) and catalase (CAT) to eliminate reactive oxygen species produced by macrophages did not lead to recovery of NO levels in hepatocytes. However, when NO synthesis was inhibited in macrophages by NG-monomethyl-L-arginine (L-NMMA), hepatocytes recovered the capacity to produce NO. A net decrease of prostaglandin E2 (PGE2) release by macrophages was concomitantly observed. Moreover, inhibition of PGE2 production in macrophages by indomethacin led to restoration of NO levels. Taken together, our observations suggest that NO synthesized by macrophages can decrease NO production in hepatocytes via PGE2 release. Because of the protective role of NO toward many liver injuries, it may be postulated that macrophages contribute through this mechanism to liver damage.
 ...
PMID:Macrophage-induced inhibition of nitric oxide production in primary rat hepatocyte cultures via prostaglandin E2 release. 979 15

Because acute infection and inflammation affect drug metabolism and drug-metabolizing enzymes, the effect of the acute-phase response on the expression of glutathione S-transferase (GST) isoenzymes, glutathione synthesis, and several antioxidant enzymes was investigated. Hepatic expression of GST isozymes, positive and negative acute-phase reactants, and antioxidant enzymes were determined by Northern blotting and hybridization with gene-specific oligonucleotide probes after lipopolysaccharide treatment of rats. Lipopolysaccharide caused the expected acute-phase response as judged by the increased expression of positive and decreased expression of negative acute-phase proteins. The messenger RNA (mRNA) expression of the major hepatic rat GST isozymes A1, A2, A3, M1, and M2 was decreased 50% to 90%. Total hepatic GST activity toward 1-chloro-2,4-dinitrobenzene was also significantly decreased. mRNA expression of gamma-glutamylcysteine synthetase (GCS) large subunit and catalase was reduced by approximately 60%. GCS enzyme activity was also decreased, resulting in a 35% decrease in the hepatic content of reduced glutathione 4 days after lipopolysaccharide challenge. Mn-Superoxide dismutase expression was increased 13-fold, and thioredoxin level was elevated 3-fold after lipopolysaccharide challenge. The expression of all parameters determined returned to near control levels 7 days after treatment. Together, these data show that GSTs and GCS are negative acute-phase proteins and that decreased GCS activity results in a decrease in hepatic glutathione content. Thus, in addition to the phase I drug-metabolizing enzymes known to be decreased during the acute-phase response, some phase II enzymes involved in the elimination of xenobiotics and carcinogens are also decreased.
 ...
PMID:Identification of glutathione S-transferase isozymes and gamma-glutamylcysteine synthetase as negative acute-phase proteins in rat liver. 982 19


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>