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)

Gram-negative septicemia remains one of the most serious forms of hospital-acquired infection. The most consistently virulent component of the gram-negative lipopolysaccharide (endotoxin) appears to be lipid A. Elucidation of the structure-function relationships of lipid A and the biochemical configurations required for endotoxicity makes possible the design of lipopolysaccharide antagonists and/or the production of poly- or monoclonal antibodies that may abrogate the biologic effects of endotoxin. The mechanisms of activity of lipopolysaccharide and the pathophysiologic events it triggers are now better understood than in the recent past. Lipid A triggers the release of mediators such as cachectin (tumor necrosis factor), thereby initiating a cascade of potentially lethal events. Although recent studies indicate no routine role for corticosteroids in gram-negative septic shock or acute respiratory distress syndrome, considerable progress has been made in the development of effective antibiotics. Recent studies of septicemia in neutropenic patients show survival rates significantly higher than those reported more than two decades ago.
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PMID:University of California/Davis Interdepartmental Conference on gram-negative septicemia. 168 79

This review suggests that infections are potent immunomodulators by causing significant alterations in one or more mediators of homeostasis and that an effective antibiosis may be a potent immunomodulator, albeit indirectly. When large numbers of microorganisms are killed, their enzymes and toxins are rapidly released and activate the immune system. The septic syndrome and the potentially progressive states of septic shock, acute respiratory distress syndrome and multiple organ system failure illustrate the biological response modulating (BRM) activity of both infection and antibiotic. Enhancement of phagocytosis and intracellular killing would be a useful immunomodulatory activity for antibiotics. Equally useful would be the capacity of the antibiotic to bind or inactivate bacterial lipopolysaccharide (LPS) to diminish monocyte release of tumour-necrosing factor (TNF) at a rate equal to or faster than the killing effect of the antibiotic on bacteria. For other types of immune deficiencies, such as are observed in HIV-positive patients with secondary bacterial, fungal and viral infections, modulation of viral receptors including HIV-R on CD4 lymphocytes accompanied by their up-regulation, enhancement of interferon (IFN) and natural killer (NK) function and inhibition of CD8 suppressor activity would be important activities. The classic example of polymyxin as an immunomodulating, albeit toxic, antibiotic offers a rational and definitive basis for the concept. In-vitro data on cefodizime, a third generation cephalosporin that achieves good tissue levels, are presented and show the ability of the intact antibiotic, as well as its immunomodulating side-chain, to down-regulate TNF and interleukin 1 (IL-1) released from human monocytes by lectin-activated lymphocytes, LPS and IFN.
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PMID:Antibiotics as biological response modifiers. 207 50

Recent reports have shown that prostaglandin E2 (PGE2) is able to suppress lipopolysaccharide (LPS)-stimulated production of tumor necrosis factor-alpha (TNF-alpha). In the present study we compared PGE2 with prostacyclin (PGI2) analogs in their potency to influence LPS-stimulated production of interleukin-1 beta (IL-1 beta) and TNF-alpha by human mononuclear cells (MNC). Our results show, that the stable analogs of PGI2, iloprost and cicaprost, markedly suppress TNF-alpha synthesis in LPS-stimulated MNC without effect on IL-1 beta production. Although there was no significant difference in maximal suppression of TNF-alpha, iloprost and cicaprost reached suppression to 50% of control at 20-fold lower concentrations than PGE2. The ID50 for iloprost and cicaprost were 8 nM and 5 nM, respectively, compared to 125 nM for PGE2. Moreover, the prostacyclin analogs as well as PGE2 suppressed LPS-induced production of TNF-alpha in Mono Mac 6 cells, a permanent human cell line with characteristics of mature monocytes. Suppression of TNF-alpha synthesis by cicaprost and PGE2 is probably mediated by an increased intracellular cAMP formation. We were able to show elevated cAMP levels with 1 microM and 10 microM of PGE2 and cicaprost in this system. The suppression of TNF-alpha synthesis may add to the beneficial effects of iloprost reported in animal models of acute respiratory distress syndrome (ARDS) and may offer a therapeutic approach in TNF-alpha mediated pathologic processes.
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PMID:Prostacyclin analogs suppress the synthesis of tumor necrosis factor-alpha in LPS-stimulated human peripheral blood mononuclear cells. 750 98

Nitric oxide (NO.) has proven effective in improving oxygenation and reducing pulmonary hypertension in the acute respiratory distress syndrome (ARDS), but the precise mechanism remains unclear. NO. has been shown to reduce leukocyte-endothelial adhesion, attenuate neutrophil (PMN) sequestration, and protect endothelium from an inflammatory insult. Intercellular adhesion molecule (ICAM)-1 is a pivotal regulator of PMN-endothelial adhesion and, thus, a critical mediator of PMN cytotoxicity. Consequently, we hypothesized that NO. suppresses ICAM-1 expression on endothelium. Human umbilical vein endothelial cells (HUVEC) were cultured. The NO. donor 3-morpholinosidnonimine (SIN-1) (0.1-10 microM) was incubated with HUVEC for 4 hr. In separate experiments, HUVEC were incubated with bacterial lipopolysaccharide (LPS) (100 ng/ml) alone or following SIN-1 pretreatment. ICAM-1 expression on HUVEC was measured by flow cytometric analysis. SIN-1 (1 and 10 microM) reduced the expression of ICAM-1 on resting HUVEC by 58 and 47%, respectively. LPS upregulated ICAM-1 expression; however, this was not affected by SIN-1 pretreatment. We conclude that NO. reduces constitutive endothelial expression of ICAM-1, but does not prevent LPS-stimulated upregulation of ICAM-1 expression. Downregulation of ICAM-1 may be a mechanism whereby NO. protects resting endothelium (distant organ bed) from circulating primed or activated PMNs, but may not be as effective at a primary inflammatory site.
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PMID:Nitric oxide reduces endothelial expression of intercellular adhesion molecule (ICAM)-1. 866 Dec 20

To understand the basis for the refractory nature of acute respiratory distress syndrome (ARDS) to glucocorticoids, the effects of dexamethasone pretreatment (DEX, 2 mg/kg, intraperitoneally) on the kinetics of airway tumor necrosis factor-alpha (TNF alpha) and macrophage inflammatory protein 2 (MIP-2) production, and polymorphonuclear leukocyte (PMN) influx after intratracheal lipopolysaccharide (LPS) (1 mg/kg) in rats were investigated. In the absence of exogenous glucocorticoids, TNF alpha and MIP-2 levels in bronchoalveolar lavage (BAL) fluid peaked at 21 and 300 ng, respectively, by 3 h. DEX pretreatment resulted in a 74% reduction in BAL TNF alpha, yet MIP-2 accumulation was unchanged. In addition, DEX reduced PMN influx at 5 h by 58.4% to 4.1 +/- 0.7 x 10(6) PMN (n = 5). DEX, however, did not mitigate the 3-fold increase in total BAL protein observed at 5 h, attributable to albumin influx. The effects of subacute DEX treatment (3.8 mg/kg per day, for 3 days) on cell-surface expression of the adhesion molecules CD11a, CD11b, and L-selectin were determined by flow cytometric analysis of peripheral blood and autologous BAL PMN. Compared with peripheral blood PMN, exudative PMN had 4-fold greater CD11b expression, no change in CD11a, and loss of L-selectin immunoreactivity 5 h after LPS challenge. The upregulation of CD11b on exudative PMN was insensitive to DEX pretreatment, which, together with a failure to suppress MIP-2 levels, provides a possible explanation for the lack of efficacy of steroids in the management of ARDS.
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PMID:Glucocorticoid effects in an endotoxin-induced rat pulmonary inflammation model: differential effects on neutrophil influx, integrin expression, and inflammatory mediators. 867 28

We evaluated the effects of antithrombin III (AT III) on the pulmonary vascular injury induced by injecting rats with lipopolysaccharide (LPS) to investigate the possible usefulness of AT III as a treatment for acute respiratory distress syndrome. The intravenous administration of AT III prevented the pulmonary accumulation of leukocytes (as evaluated by myeloperoxidase activity) and the increase in pulmonary vascular permeability to 125I-bovine serum albumin induced by LPS. The increase in pulmonary vascular permeability induced by LPS administration was unaffected by various anticoagulants but was inhibited by the leukocytopenia induced by nitrogen mustard or by the administration of a granulocyte elastase inhibitor, ONO-5046. AT III given alone, but not heparin plus AT III or Trp49-modified AT III, which lacks affinity for heparin, significantly increased the plasma concentration of 6-keto-prostaglandin F1alpha, suggesting that the interaction of AT III with heparin-like substances at the endothelial cell surface promotes the release of prostacyclin from endothelial cells in vivo. Trp49-modified AT III failed to prevent the LPS-induced accumulation of leukocytes and vascular injury. The pulmonary accumulation of leukocytes and vascular injury induced by LPS were not prevented by administering AT III to rats that were pretreated with indomethacin. The continuous intravenous infusion of prostacyclin prevented the LPS-induced pulmonary accumulation of leukocytes and vascular injury. Findings suggest that AT III depends on its ability to promote the release of prostacyclin, a potent inhibitor of leukocyte activation, from endothelial cells to prevent pulmonary vascular injury induced by LPS.
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PMID:Attenuation of endotoxin-induced pulmonary vascular injury by antithrombin III. 876 16

We evaluated the effect of interleukin-6 (IL-6) on the production of prostacyclin (PGI2) by cultured human pulmonary artery smooth muscle cells (HPASMC). Incubation of these cells for up to 48 h with IL-6 led to a dose- and time-dependent decrease in the concentration of PGI2 in the culture medium. The incubation of HPASMC with 10 micrograms/ml of lipopolysaccharide (LPS), 200 U/ml of IL-1 beta, or 500 U/ml of TNF alpha for 24 hr significantly increased the concentration of PGI2 in the medium. However, the addition of IL-6 to a medium containing LPS, IL-1 beta, or TNF alpha significantly inhibited the stimulatory effect of those substances on PGI2 production. Such inhibition was closely related to the concentration of IL-6. IL-6 may counteract the roles of LPS and of other cytokines on the regulation of pulmonary vascular tension in endotoxin- and cytokine-mediated disorders such as sepsis and the acute respiratory distress syndrome (ARDS).
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PMID:Inhibitory effects of interleukin-6 on release of PGI2 by cultured human pulmonary artery smooth muscle cells. 888 Aug 95

Little is known on the haemostatic profiles of human microvascular endothelial cells (MVEC) from different tissues. In addition it is not known whether MVEC from patients display the same haemostatic pattern as MVEC coming from healthy controls. To address these questions MVEC from human lung and brain were isolated and stimulated with tumour necrosis factor alpha (TNF) and E. coli lipopolysaccharide (LPS) for 24 h. The level and the kinetics of procoagulant activity (PCA) and thrombomodulin (TM) expression were found to be different depending on the tissue of origin and on the agonist used. In particular, the inducible PCA was higher in lung than in brain MVEC, an observation that may be related to the frequency of lung involvement in septic shock. Differences were also observed for tissue plasminogen activator (t-PA) and plasminogen activator inhibitor 1 (PAI-1) with MVEC supernatants or cell lysates. These variables were then measured in lung MVEC purified from patients with acute respiratory distress syndrome (ARDS) and compared to controls. Cells from ARDS patients constitutively expressed more PCA and PAI-1 than controls. The fibrinolytic potential, expressed as t-PA/PAI-1 ratio, was lower in ARDS than in lung MVEC. It is concluded that MVEC display different haemostatic features depending on the tissue they come from and that lung MVEC from ARDS patients present a procoagulant profile when compared with those from controls.
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PMID:Haemostatic properties of human pulmonary and cerebral microvascular endothelial cells. 906 14

The effects of bacterial endotoxin (lipopolysaccharide, LPS) are amplified by lipopolysaccharide binding protein (LBP) and CD14, resulting in cellular activation at very low concentrations of LPS. To investigate the importance of this pathway in acute lung injury, we measured LPS, LBP, and soluble CD14 (sCD14) in the bronchoalveolar lavage fluid (BAL) of 82 patients with acute respiratory distress syndrome (ARDS). LBP and sCD14 increased markedly in BAL of patients with ARDS. sCD14 and LBP each were strongly related to BAL total protein and polymorphonuclear neutrophil (PMN) concentration, whereas LPS concentration was not. Multivariate analyses showed sCD14 to be strongly related to BAL total protein, even after controlling for LPS and LBP concentrations. sCD14 was strongly and independently related to PMN concentration, after controlling for BAL LPS, LBP, and interleukin-8 (IL-8). The BAL LPS concentration was not strongly related to either BAL total protein or BAL PMN. The BAL sCD14 and LBP values were similar in all subgroups of patients with ARDS, and were not related to survival. The serum LBP and sCD14 were elevated in ARDS, but were not related to BAL total protein, LBP, sCD14, PMN, or clinical outcome. Thus, LBP and sCD14 reach high concentrations in the lungs of patients with ARDS, and BAL sCD14 is strongly related to two major indices of lung inflammation: total protein and PMN concentration. CD14-dependent mechanisms may contribute to lung inflammation in ARDS.
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PMID:Relationship between soluble CD14, lipopolysaccharide binding protein, and the alveolar inflammatory response in patients with acute respiratory distress syndrome. 911 29

We have herein established an endotoxemia-induced acute respiratory distress syndrome (ARDS)-like lung injury administered a sublethal dose of lipopolysaccharide (LPS) intravenously 36 hours after the intratracheal instillation of heat-killed Streptococcus pyogenes (OK-432). At 36 hours after OK-432 priming, a mild infiltration into the lungs, consisting of a small number of neutrophils and macrophages, was observed without destruction of pulmonary architecture. A subsequent challenge with a sublethal dose of LPS induced pathologic changes characteristic of ARDS--such as extensive edema in alveolar lumina, marked infiltration composed of a large number of neutrophils and a few macrophages, fibrin deposit in alveolar space, and destruction of pulmonary architecture--resulting in severe hypoxemia. Concomitantly, LPS challenge after priming with OK-432 induced a marked elevation of IL-8 levels in serum and bronchoalveolar lavage fluid with local IL-8 production in lungs, as revealed by immunohistochemical analysis. An anti-IL-8 antibody treatment almost completely prevented pulmonary edema, destruction of pulmonary architecture, and impairment in gas exchange as well as neutrophil infiltration in lungs; there was also a significant reduction in the rate of acute lethality. These results provide evidence that IL-8 has a pivotal role in the induction of ARDS associated with endotoxemia, probably by recruiting and activating neutrophils locally.
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PMID:Prevention of endotoxemia-induced acute respiratory distress syndrome-like lung injury in rabbits by a monoclonal antibody to IL-8. 912 Nov 20


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