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Query: UNIPROT:P43026 (lipopolysaccharide)
 62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Polymyxin B (PmB), an agent often used to neutralize the effects of bacterial lipopolysaccharide (LPS), was shown to exert a dose-dependent stimulatory effect on the biosynthesis of C3, factor B, interleukin-6 (IL-6), and granulocyte-macrophage colony-stimulating factor (GM-CSF) in human monocytes. A low dose of PmB (1 to 5 micrograms/ml) efficiently suppressed the LPS-induced (1 or 100 ng/ml) production of IL-6, GM-CSF, and factor B, but not the C3 production induced by 100 ng of LPS per ml. A reduced level of GM-CSF may have contributed to the persisting high C3 concentrations and the apparent lack of LPS inhibition in the latter situation, since GM-CSF is an inhibitor of monocyte C3 biosynthesis.
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PMID:Polymyxin B stimulates production of complement components and cytokines in human monocytes. 772 27

Endotoxin (lipopolysaccharide) is a cell wall polymer from gram-negative bacteria that stimulates Kupffer cell release of cytokines such as tumor necrosis factor-alpha and interleukin-1. Another bacterial cell wall polymer in both gram-negative and gram-positive organisms is peptidoglycan-polysaccharide. Lipopolysaccharide and peptidoglycan-polysaccharide exist together in the intestinal lumen and can cross the intestinal mucosa, enter the portal vein and activate Kupffer cells. The purpose of this study was to compare the effects of lipopolysaccharide stimulation and peptidoglycan-polysaccharide stimulation of Kupffer cells on release of tumor necrosis factor-alpha and interleukin-1. Both bacterial polymers caused maximum tumor necrosis factor-alpha release from Kupffer cells after incubation for 4 to 8 hr. Maximum tumor necrosis factor-alpha release induced by 400 ng/ml lipopolysaccharide was 704 +/- 258 pg/ml, compared with 329 +/- 91 pg/ml tumor necrosis factor-alpha after 100 micrograms/ml peptidoglycan-polysaccharide (p < 0.001). Polymyxin B blocked lipopolysaccharide stimulation of tumor necrosis factor-alpha by 95% +/- 5% but blocked peptidoglycan-polysaccharide-stimulated tumor necrosis factor-alpha by 30% +/- 14% (p < 0.001). Repeat incubation of Kupffer cells with lipopolysaccharide after prior lipopolysaccharide incubation induced low tumor necrosis factor-alpha release (tolerance). Repeat incubation with peptidoglycan-polysaccharide induced no tolerance to tumor necrosis factor-alpha release. Incubation of lipopolysaccharide plus peptidoglycan-polysaccharide released less tumor necrosis factor-alpha than did each polymer used alone, but this inhibition was prevented by indomethacin. Dibutyryl cyclic AMP, prostaglandin E1, prostaglandin E2 and the adenosine A2-receptor agonist N-ethylcarboxyamideadenosine inhibited lipopolysaccharide-stimulated tumor necrosis factor-alpha release by 83%, 97%, 90% and 94%, respectively, but inhibited peptidoglycan-polysaccharide-stimulated tumor necrosis factor-alpha release by 52%, 60%, 45% and 51%, respectively (p < 0.001 for each). This indicates that intracellular signaling pathways differ for lipopolysaccharide-stimulated and peptidoglycan-polysaccharide-stimulated tumor necrosis factor-alpha release. After incubation for 8 and 24 hr, 100 micrograms/ml peptidoglycan-polysaccharide had induced significantly more interleukin-1 release from cultured Kupffer cells than had 400 ng/ml lipopolysaccharide (p < 0.001). Lipopolysaccharide induced tolerance to interleukin-1 release after repeat incubation, but peptidoglycan-polysaccharide caused no tolerance. These studies show that peptidoglycan-polysaccharide, a ubiquitous bacterial cell wall polymer, shares several proinflammatory properties with lipopolysaccharide but that there are differences that may have pathophysiological significance.
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PMID:Comparison of peptidoglycan-polysaccharide and lipopolysaccharide stimulation of Kupffer cells to produce tumor necrosis factor and interleukin-1. 813 41

Fibroblasts play an indirect augmenting effector role in the inflammatory response by releasing growth and differentiation factors and other inflammatory mediators after activation by inflammatory cytokines such as interleukin (IL)-1, but whether direct activation occurs by exogenous agents such as endotoxin (lipopolysaccharide, LPS) remains controversial. Using a number of primary human airways tissue-derived fibroblast lines, we demonstrate that in contrast to IL-1 alpha, LPS significantly induced gene expression and production of granulocyte/macrophage colony-stimulating factor (GM-CSF), IL-8, and IL-6 only in nasal but not bronchial or lung tissue-derived fibroblasts. Enhanced expression was dose- and time-dependent, and the minimal stimulatory dose was 10 ng LPS/ml. Polymyxin B entirely abrogated increased cytokine expression by LPS. Actinomycin D treatment largely inhibited expression, and LPS markedly increased an IL-6 gene promoter-driven luciferase reporter response in transfected nasal fibroblasts, suggesting enhanced expression may involve transcriptional regulation. Secondary protein or IL-1 synthesis requirement seemed unlikely since cycloheximide superinduced LPS-stimulated cytokine expression and anti-IL-1 alpha/beta antibodies failed to abrogate the response. Thus our data show that GM-CSF, IL-8, and IL-6 are directly inducible in nasal fibroblasts by LPS, and establish heterogeneous responsiveness to LPS by different fibroblast populations in the airways.
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PMID:Lipopolysaccharide induces expression of granulocyte/macrophage colony-stimulating factor, interleukin-8, and interleukin-6 in human nasal, but not lung, fibroblasts: evidence for heterogeneity within the respiratory tract. 839 62

Polymyxin B (PmB) in the concentration range of 10-50 micrograms/ml is used routinely in immunological studies to neutralize low levels of contaminating lipopolysaccharide (LPS) in media or reagents. While using PmB for such a purpose unexpected results were obtained, which led to the finding that low levels of PmB are cytotoxic to certain tumor cells. Further examination of a panel of 10 tumor cell lines revealed that in an 18-hour 51Cr release assay, EL4 cells and EL4/ADM cells were very sensitive (lysed by > or = 10 micrograms PmB/ml), C1498 cells and REH cells were moderately sensitive (lysed by > or = 20 micrograms PmB/ml) and cells of the remaining 6 lines were resistant (lysed only by 100 micrograms/ml) to PmB. A similar pattern of sensitivity was observed when 3H-thymidine incorporation was used as a measure of PmB effects in cell proliferation. The PmB concentration needed to kill 50% of the tumor cells in a suspension differed greatly among lines; thus for cells of a resistant line 8-fold more PmB was required for 50% killing than for those of a sensitive line. PmB toxicity toward EL4 cells was shown to increase to a plateau level with increasing time of exposure; however, the higher the concentration the earlier the plateau was reached. LPS may prevent PmB toxic effects since PmB binds to the lipid A portion of the LPS molecule, but 100 micrograms LPS/ml was only able to reduce the toxicity of 10 and 20 micrograms PmB/ml, and not that of 50 or 100 micrograms PmB/ml.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Polymyxin B-mediated lysis of tumor cells. 842 63

Magainins are novel polycationic peptides with broad-spectrum antimicrobial activity, including activity against gram-negative bacteria. Gram-negative bacteremia can elicit endotoxic shock that is associated with the increased formation of eicosanoids. Inhibition of eicosanoid synthesis has been shown to improve the outcome of experimental endotoxic shock. The aim of the present study was to test the in vitro effects of two magainin peptides, MSI-97 (M1) and MSI-98 (M2), on eicosanoid synthesis by rat peritoneal macrophages (M phi) stimulated by Salmonella enteritidis lipopolysaccharide (LPS; 50 micrograms/ml) and Salmonella minnesota lipid A (5 micrograms/ml) and to compare their effects on LPS reactivity with a metachromatic dye. M1 (100 micrograms/ml) significantly (P < 0.05) reduced LPS-stimulated synthesis of thromboxane B2 (TXB2), without changing 6-keto-prostaglandin F1 alpha in M phi. Similarly, M2 (10 micrograms/ml) significantly attenuated M phi synthesis of TXB2 stimulated by either LPS or lipid A. However, at a higher concentration (100 micrograms/ml), M2 but not M1 significantly augmented LPS-induced increases in TXB2 and 6-keto-prostaglandin F1 alpha. Polymyxin B (40 micrograms/ml) inhibited LPS production and lipid A-stimulated TXB2 production. M1 (100 micrograms/ml) and polymyxin B (10 and 40 micrograms/ml) also inhibited calcium ionophore A23187 (10 microM)-induced synthesis of TXB2. The lipid A moiety of LPS reacts with dimethylmethylene blue dye, providing a metachromatic assay of LPS. This metachromatic reaction with lipid A was significantly reduced by polymyxin B and M2 at all concentrations. M1 was effective only at the highest M1:lipid A concentration ratio (2:1). Thus, M1 and M2 share some similarities with polymyxin B in inhibiting lipid A reactivity with the dye, which suggests that these magainins may also bind to lipid A. However, M1 was devoid of any inhibitory effects on dye reactivity with S. enteritidis LPS and M2 was inhibitory at only one concentration ratio (1:5). In conclusion, the varied effects of the magainin peptides on LPS, lipid A, and M phi eicosanoid synthesis appear to depend on the type of peptide used and on its concentration.
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PMID:Effects of two magainin peptides on eicosanoid release from rat peritoneal macrophages. 846 Sep 10

There is increasing evidence that lipoproteins of Treponema pallidum and Borrelia burgdorferi are key inflammatory mediators during syphilis and Lyme disease. A principal objective of the present study was to identify more precisely similarities and divergences among lipopolysaccharide (LPS)- and lipoprotein-lipopeptide-induced immune cell signaling events. Like LPS, purified native B. burgdorferi OspA and synthetic analogs of OspA, OspB, and two T. pallidum lipoproteins (Tpp47 and Tpp17) all induced NF-kappa B translocation in THP-1 human monocytoid cells. Acylation of OspA and the synthetic peptides was requisite for cell activation. Polymyxin B abrogated only the response to LPS. By using 70Z/3-derived pre-B-cell lines either lacking or expressing human CD14 (the LPS receptor), it was observed that expression of human CD14 imparted responsiveness to LPS but not to OspA or spirochetal lipopeptides (assessed by induction of NF-kappa B and expression of surface immunoglobulin M). Finally, the biological relevance of the observation that T. pallidum lipoproteins-lipopeptides induce both NF-kappa B and cytokine production in monocytes was supported by the ability of the synthetic analogs to promote human immunodeficiency virus replication in chronically infected U1 monocytoid cells; these observations also suggest a potential mechanism whereby a syphilitic chancre can serve as a cofactor for human immunodeficiency virus transmission. The combined data lend additional support to the proposal that spirochetal lipoproteins and LPS initiate monocyte activation via different cell surface events but that the signaling pathways ultimately converge to produce qualitatively similar cellular responses.
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PMID:Activation of human monocytic cells by Treponema pallidum and Borrelia burgdorferi lipoproteins and synthetic lipopeptides proceeds via a pathway distinct from that of lipopolysaccharide but involves the transcriptional activator NF-kappa B. 875 37

We have previously demonstrated that the membrane of the Staphylococcus aureus L form induced tumor necrosis factor alpha (TNF-alpha) from murine macrophages. In this study, we purified two proteins which induce TNF-alpha production from a human monocytic cell line, THP-1, and murine macrophages. These molecules were purified from delipidated membranes by deoxycholic acid extraction, two-step anion-exchange chromatography, and preparative electrophoresis. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified proteins showed for each a single band with a molecular mass of 30, and 36 kDa. These proteins were heat stable. Polymyxin B did not affect the production of TNF-alpha induced by these proteins. Furthermore, these proteins induced comparable levels of TNF-alpha in both lipopolysaccharide-responsive and -nonresponsive mouse macrophages. Pretreatment of murine macrophages with gamma interferon enhanced 30- and 36-kDa protein-mediated TNF-alpha production. The 30-kDa protein showed lethal toxicity to D-galactosamine-treated mice. The 30- and 36-kDa proteins stimulated the human immunodeficiency virus type 1 long terminal repeat in a monocytic cell line but not a T-cell line. This effect appeared to be mediated through the induction of nuclear factor kappaB. These results indicate that the 30- and 36-kDa proteins, membrane constituents of the S. aureus L form, may play a role in S. aureus infection and/or in human immunodeficiency virus type 1-infected individuals.
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PMID:Proteins of 30 and 36 kilodaltons, membrane constituents of the Staphylococcus aureus L form, induce production of tumor necrosis factor alpha and activate the human immunodeficiency virus type 1 long terminal repeat. 875 63

An extracellular surface-active agent, PM-factor, was obtained by high-speed centrifugation from the culture broth of Pseudomonas marginalis PD-14B. PM-factor exhibited emulsifying activity on a broad spectrum of hydrocarbon liquids, including aromatics, aliphatics, crude oil, and creosote. The factor appeared as ball-shaped particles of varying diameter when examined by electron microscopy (0.16-1.4 microns). Gel filtration chromatography demonstrated a high molecular mass of the factor (> 10(6) Da). The ultraviolet absorption spectrum manifested a peak in the region 200 nm rather in the region 260-280 nm. Amino acid analysis showed a very low amount of aromatic amino acids residues in the protein moiety of PM-factor. The presence of 3-deoxy-D-mannooctulosonic acid, heptose, hexosamine, phosphorus, and 3-hydroxy fatty acid indicated that PM-factor contained lipopolysaccharide. The emulsifying activity of PM-factor was inhibited strongly by mercuric chloride and moderately by EDTA. Polymyxin B, Ca2+, and Mg2+ markedly stimulated the factors emulsifying activity. Roles of the bioemulsifier in the functioning of P. marginalis as a plant pathogen and in bioremediation are discussed.
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PMID:Physicochemical properties of PM-factor, a surface-active agent produced by Pseudomonas marginalis. 886 31

The lipopolysaccharide endotoxin is the most powerful immune stimulant known and a causative agent in the clinical syndrome known as sepsis. Sepsis is responsible for more than 100,000 deaths annually, in large part due to the lack of a rapid, reliable, and sensitive diagnostic technique. This study describes the detection of LPS from E. coli at concentrations as low as 10 ng/mL, in 30 s using an evanescent wave fiber-optic biosensor. Polymyxin B, covalently immobilized onto the surface of the fiber-optic probe, selectively bound fluorescently labeled LPS. Unlabeled LPS was detected in a competitive assay format using labeled LPS for signal generation. The competitive assay format worked in both buffer and plasma with similar sensitivities. This method can be used with other LPS capture molecules such as antibodies, lectins, or antibiotics, to simultaneously detect LPS and to determine the LPS serotype. The LPS assay using the fiber-optic biosensor is applicable to both clinical and environmental testing.
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PMID:Detection of endotoxin using an evanescent wave fiber-optic biosensor. 893 15

The purpose of this study was to assess whether polymyxin B together with pentoxifylline, had beneficial effects on the acute-phase-response to E. coli endotoxin in the dwarf goat (n = 6). Polymyxin B partly neutralizes E. coli endotoxin by forming inactive polymyxin B-lipopolysaccharide (LPS) complexes; pentoxifylline has been reported to suppress the LPS-induced production of tumour necrosis factor (TNF-alpha). E. coli LPS (0.0067 microgram/kg/min over 30 min) induced fever, tachycardia, inhibition of rumen motility, a decline in WBC, lymphopenia, and decreases in plasma zinc and iron concentrations. Most of the haematological, blood biochemical and clinical effects of E. coli LPS were significantly reduced by polymyxin B pretreatment (0.1 mg/kg/min over 30 min, i.v.). Pentoxifylline (0.3 mg/kg/min over 30 min, i.v.) did not reduce the clinical and blood biochemical effects of E. coli LPS, however, it modulated the number of circulating neutrophils. No synergistic effects were observed after i.v. infusion of polymyxin B with pentoxifylline. The lack of synergy may be due to the production and release of pro-inflammatory cytokines other than TNF-alpha.
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PMID:Effects of pentoxifylline and polymyxin B on the acute-phase-response to Escherichia coli endotoxin in dwarf goats. 904 51


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