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)

In the previous paper we have demonstrated that progesterone-treated lymphocytes of healthy pregnant women produce a 34,000 MW protein that inhibits cytotoxic activity and prostaglandin F2 alpha synthesis. Since recently it has been shown that certain leukotrienes have a stimulatory effect on natural killer activity, in this study an attempt was made to determine whether there is a relationship between cytotoxicity and PGF2 alpha synthesis or if alterations in the values of these parameters are independent. Arachidonic acid increased cytotoxic activity of healthy pregnant women's peripheral blood mononuclear cells (PBMC) in a concentration-dependent manner. Exogenous arachidonic acid was able to counteract the blocking effect of the above-mentioned protein produced by progesterone-treated lymphocytes. To determine whether the products of the cyclooxygenase or the lipoxygenase pathway of arachidonic acid metabolism are responsible for increased cytotoxicity, both enzyme systems were blocked separately. Both indomethacin and the lipoxygenase inhibitor BW 755C reduced cytotoxicity in a dose-dependent fashion. However, the lipoxygenase inhibitor prevented prostaglandin synthesis to the same extent, or even more than indomethacin, in all concentrations used; so, its blocking effect cannot be considered as supportive evidence for the role of leukotrienes in cytotoxicity. On the other hand, lipopolysaccharide, with a selective stimulatory effect on prostaglandin synthesis, increased cytotoxicity. Lipopolysaccharide had no effect on progesterone-pretreated PBMC. The above data allow the assumption that besides leukotrienes, cyclooxygenase products may also increase cytotoxicity.
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PMID:The mechanism of the inhibitory effect of progesterone on lymphocyte cytotoxicity: II. Relationship between cytotoxicity and the cyclooxygenase pathway of arachidonic acid metabolism. 393 86

The lethal action of endotoxin was studied in mice sensitized against the lipopolysaccharide by D-galactosamine. Protection was obtained by FPL 55712, a selective antagonist of sulfidopeptide leukotrienes, by diethylcarbamazine, an inhibitor of leukotriene biosynthesis, by BW 755C, a dual lipoxygenase and cyclooxygenase inhibitor, and by dexamethasone, which inhibits arachidonate release. Indomethacin incompletely antagonized endotoxin lethality; indoprofen did not protect at all. Leukotriene generation induced by endotoxin in vivo could be demonstrated in rats by employing a radioimmunoassay on bile extracts since intravascular sulfidopeptide leukotrienes were rapidly eliminated into bile. Additionally, however, endotoxin affected the hepatobiliary elimination of sulfidopeptide leukotrienes. From intravenously injected tracer [3H]leukotriene D4, 67% appeared only partially metabolized in bile within 30 min in control rats. Endotoxin and lipid A reduced the biliary [3H]leukotriene D4 secretion by up to 80% while enhancing the hepatic [3H]leukotriene D4 content up to twofold. This inhibition of hepatobiliary elimination was stronger than endotoxin-induced reductions of bile flow or of biliary [14C]taurocholate secretion. Endotoxin, as an activator of the arachidonate cascade, thus potentiates its action in vivo by interfering with the rapid hepatobiliary clearance of sulfidopeptide leukotrienes in addition to stimulating leukotriene and prostanoid formation.
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PMID:Role of peptide leukotrienes and their hepatobiliary elimination in endotoxin action. 609 38

We have evaluated the possible role of biological response modifiers (BRMs) in myelopoiesis by investigating BRM modulated secretion of hematopoietic growth factors and inhibitors. Here, we report the evidence of augmented secretion of granulocyte and/or macrophage colony stimulating factors (CSF) by murine resident peritoneal macrophages after in vitro incubation with murine interferons (alpha, beta-mIFN; beta-mIFN; gamma-mIFN), poly ICLC (polyriboinosinic-polycytidylic acid poly-L-lysine), BM 41.332 (2-cyano-1-[(2-methoxy-6-methyl-pyridin-3yl)-methyl]-aziridine) and lipopolysaccharide (LPS). The secretion of CSF appears to be independent of the ability of the BRMs to induce IFN, as shown by the use of neutralizing antibodies against mIFN. The antiproliferative effects of IFN also did not block the BRM induced effects of CSF. The combination of alpha, beta-mIFN and poly ICLC or LPS and poly ICLC at suboptimal concentrations resulted in additive, but not synergistic effects on CSF secretion by macrophages. Histological examination of the colonies induced indicated the presence of two types of CSF, namely CSF1 and CSF3, which give rise to pure macrophage and granulocyte colonies respectively. In parallel to their effect on CSF secretion, these BRMs also caused a considerable increase in secretion of prostaglandins of the E series (PGE) by macrophages. However, the production of PGE did not interfere or influence CSF secretion, since the inhibition of the enzyme cyclooxygenase with indomethacin (10(-7) molar) 3 h before stimulation with poly ICLC, alpha, beta-mIFN, or LPS, inhibited the secretion of PGE by macrophages without affecting the secretion of CSF. Macrophages, stimulated by one of the active BRMs for 24 h, could not be restimulated by any of these agents to again secrete significant amounts of CSF or PGE, even after a 2 day resting phase. Other drugs tested (diethyldithiocarbamate, maleic anhydride divinyl ether, azimexone) failed to stimulate the in vitro secretion of significant amounts of CSF and PGE. The results presented here indicate that several BRMs can be utilized to stimulate macrophages to secrete the myelopoietic growth factor CSF, thus supporting the concept that these BRMs might be of value in reconstituting or promoting impaired granulocyte and monocyte/macrophage function.
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PMID:Role of prostaglandin E and interferon in secretion of colony-stimulating factor by murine macrophages after in vitro treatment with biological response modifiers. 620 28

The effect of heat-aggregated immunoglobulin G's (HAgg-IgGs) on bacterial lipopolysaccharide- (LPS) induced polyclonal B cell activation (PBA) was studied. HAgg-IgGs (10 micrograms/ml or more) that were added to cultures of spleen cells obtained from BALB/c mice remarkably decreased the numbers of anti-trinitrophenyl (TNP) antibody-producing cells (APC) generated by LPS in cultures. This suppressive effect was seen when HAgg-IgGs were added within 1 hr after the initiation of culture. Later addition of HAgg-IgGs did not cause any effective suppression of the generation of APC. Moreover, the spleen cells, which had been pretreated with HAgg-IgGs, washed for removal of free HAgg-IgGs, and subsequently cultured, responded poorly to LPS. HAgg-IgG2b was more effective than HAgg-IgGs, but HAgg-IgG2a did not have any suppressive effect. A similar suppressive effect was observed when HAgg-IgG2b-Fc was added into culture, whereas none was noted with IgG2b-Fab. Indomethacin (IM), known as cyclooxygenase inhibitor, could completely abrogate the suppressive effects of HAgg-IgGs on LPS-induced PBA responses when it was added to the cell cultures together with HAgg-IgGs or to the cultures of HAgg-IgGs-pretreated cells. Addition of prostaglandin E2 (PGE2) showed strong suppression of the PBA responses of spleen cell cultures that had been pretreated with HAgg-IgGs and IM, but other PG analogues showed no suppression. Thus, it would appear that PGE2 has some role in the suppression of the LPS-induced PBA response.
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PMID:Suppression of lipopolysaccharide-induced polyclonal B cell activation of murine spleen with heat-aggregated murine immunoglobulin G. 622 74

Kupffer cells exposed to bacterial lipopolysaccharide in vitro synthesized collagenase and released the major portion of it into the extracellular space while the intracellular level of enzyme was not altered significantly. Cycloheximide prevented the appearance of collagenase in the medium indicating de novo synthesis. Indomethacin, an inhibitor of cyclooxygenase, also blocked collagenase synthesis. In line with this observation. Kupffer cells were found to synthesize substantial amounts of prostaglandin E2 when exposed to lipopolysaccharide; concomitantly, cellular cAMP levels were increased. Indomethacin was shown to abolish the stimulated cAMP formation. Addition to the culture medium of cAMP or dibutyryladenosine 3', 5'-monophosphate as well as of prostaglandin E2 or, to a lesser extent, prostaglandin E1 allowed indomethacin-inhibited cells to resume the production of collagenase. It is proposed that in rat Kupffer cells lipopolysaccharide-elicited collagenase synthesis and excretion is mediated sequentially by stimulated production of prostaglandin E2, enhanced adenylate cyclase activity and increased intracellular cAMP levels.
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PMID:Involvement of prostaglandin E and adenosine 3', 5'-monophosphate in lipopolysaccharide-stimulated collagenase release by rat Kupffer cells. 628 7

The synthesis and secretion of prostaglandins and leukotrienes by mouse peritoneal macrophages is under several regulatory controls. Arachidonic acid must first be released from phospholipid stores by the action of phospholipases. Macrophages have the capacity to deacylate arachidonic acid directly from the SN2 position of phospholipids via the action of a phospholipase A2. In addition, these cells contain a phospholipase C capable of removing inositol-phosphate from phosphatidylinositol generating diacylglycerol. Another enzyme, diacylglycerol lipase is present to then generate arachidonic acid. The free arachidonic acid then enters the cyclooxygenase pathway to generate prostaglandins, the lipoxygenase pathway to generate leukotrienes or both pathways. The nature of the inflammatory stimulus added to these cells determines which of the above pathways become operative. Zymosan and the Ca++ ionophore, A23187 stimulate the synthesis of both prostaglandins and leukotrienes whereas phorbol myristate acetate and lipopolysaccharide induce only the synthesis of prostaglandins. In addition, the synthesis of these two products by macrophages can be regulated by certain antiinflammatory compounds. Indomethacin, aspirin, ibuprofen and benoxaprofen are only inhibitors of the prostaglandin pathway, whereas BW755C, 5,8,11-ETYA, NDGA and sulindac sulfide (high doses) are inhibitors of the synthesis of both prostaglandins and leukotrienes. Dapsone, an effective drug for leprosy, also inhibits the synthesis of both of these products.
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PMID:Physiological and pharmacological regulation of prostaglandin and leukotriene production by macrophages. 632

Human monocytes (M phi) exposed to 0.5-20 micrograms/ml of cyclosporine (CsA) produced levels of prostaglandins of the E series (PGE) that were 2-3-fold greater than control M phi cultured in medium alone. Maximal PGE levels were obtained at 24-48 hr incubation, and the failure to observe a linear increase of PGE levels at higher CsA concentrations appeared partially related to cytotoxic effects. CsA was considerably less effective than phorbol myristate acetate or bacterial lipopolysaccharide in increasing PGE production, but the PGE levels achieved with CsA approximated those known to suppress immune responsiveness. Other experiments showed that, although the increased PGE production with CsA was indomethacin-sensitive, CsA mostly functioned to increase the availability of free arachidonic acid (AA) instead of accelerating AA conversion by the cyclooxygenase pathway. Thus CsA can alter M phi physiology, and these alterations might inhibit quite early events during the induction phase of immune responses.
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PMID:Characteristics of cyclosporine induction of increased prostaglandin levels from human peripheral blood monocytes. 643 25

The products of arachidonic acid oxygenations by resident mouse peritoneal macrophages have been found to depend upon the nature of the stimulus. For example, soluble membrane-mediated inflammatory stimuli such as phorbol myristate acetate and lipopolysaccharide stimulated the formation of prostaglandin E2 via the cyclooxygenase pathway. In contrast, zymosan, a particulate, phagocytozable inflammatory mediator stimulated leukotrienes C4 and B4 synthesis via the lipoxygenase pathway in addition to stimulating prostaglandin E2 synthesis. Thus, the release of leukotrienes is not necessarily linked to the release of prostaglandins in a cell that has the enzymatic capability of producing both mediators. This suggests that the prostaglandin synthetase system can obtain substrate arachidonic acid from a source different from that for leukotriene synthesis.
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PMID:Evidence for two sources of arachidonic acid for oxidative metabolism by mouse peritoneal macrophages. 679 9

The expression of nonspecific macrophage-mediated tumoricidal activity in vitro is a transient phenomenon. The work reported here shows that the loss of tumoricidal activity by mouse macrophages is attributable, at least in part, to the effects of prostaglandin E (PGE). The amount of PGE needed to inhibit the expression of cytolytic activity (2 x 10(-9) M) was readily synthesized and secreted by the same population of resident peritoneal macrophages that had been induced to kill tumor cells by exposure to 100 ng/ml bacterial lipopolysaccharide (LPS). Inhibitory concentrations of PGE were present in supernatants within the 1st hr after macrophages were exposed to LPS. In spite of this fact, cytolytic activity still developed, and 12 to 16 hr were required for the PGE to have its full inhibitory effect. Thus, PGE did not act by blocking the development of cytolytic activity. Treatment of LPS-stimulated macrophages with 10(-6) M indomethacin (or other cyclooxygenase inhibitors) prevented both PGE synthesis and the shut-off of cytolytic activity. The latter effect could be reversed by adding PGE2 to the cultures at a concentration of 10(-8) M. Lastly, PGE inhibited cytolytic activity mediated by indomethacin-treated macrophages only when activator was present: pulsing with PGE before the addition of LPS had a negligible inhibitory effect. These findings may help explain why intratumoral macrophages often lack nonspecific cytolytic capabilities.
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PMID:Macrophage-mediated tumor cell killing: regulation of expression of cytolytic activity by prostaglandin E. 745 84

We have evaluated the role of prostaglandin E2 (PGE2) in the synthesis of nitric oxide (NO) by the activation of the inducible form of nitric oxide synthase (NOS) in the murine macrophage cell line, J774, stimulated with different doses of lipopolysaccharide (LPS). The stimulation of the J774 line with suboptimal doses of LPS (0.1 microgram/mL) caused a production of endogenous PGE2 that was capable of stimulating NOS activity inducing an increase in the NO synthesis, as attested by the fact that cyclooxygenase enzyme inhibitor, indomethacin, significantly reduced NO secretion. On the contrary, a higher dose of LPS (1 microgram/mL) produced high levels of PGE2 that reduced the levels of NOS and, subsequently, NO production. Experiments carried out with exogenous PGE2 indicated that concentrations between 1 and 10 ng/mL are able to stimulate the expression of NOS and the release of NO, while higher concentrations (> 50 ng/mL) are inhibitory. Furthermore, our data indicate that there is a network of interaction which involves NO, PGE2, and tumor necrosis factor. High levels of PGE2 inhibited TNF alpha secretion, which in turn could exert inhibitory effects on NO synthesis.
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PMID:Prostaglandin E2 regulates inducible nitric oxide synthase in the murine macrophage cell line J774. 748 Jul 96


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