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)

Treatment of outer membranes of Serratia marcescens with polymyxin B results in the formation of blebs. This effect is thought to be due to the action of the antibiotic on the lipopolysaccharides, proteins, phospholipids or a combination thereof. It is unclear whether this effect is dissociative, degradative or due to an inhibition of the assembly of outer membrane components. Prior studies showed that lipopolysaccharides and polymyxin B form complexes, but direct visualization of the in situ action of polymyxin B had not been accomplished. Isolated outer membranes normally exhibit a periodicity of the polysaccharide molecules when stained by the thiosemicarbazide-silver technique. Polymyxin B treated outer membranes display a change in their basic morphology. This effect is very drastic in the sensitive strain as demonstrated by the large gaps in the deposition of the granules in the modified outer membrane structure. Thus it appears that the polysaccharide molecules (probably the lipopolysaccharide) either alone or in association with protein or phospholipids are the primary targets of the antibiotic.
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PMID:Electron microscopic observations of polysaccharide components in polymyxin B treated outer membranes from Serratia marcescens. 8 89

Two models have been proposed to explain triggering of B cells by so-called "T-independent antigen." Feldmann and Basten (1) proposed that the interaction of multiple repeating determinants on polymeric antigens with specific Ig receptors on the B-cell surface is sufficient to provide the signals for division of these cells and differentiation to antibody-forming cells. In contrast, coutinho et al. (2, and see review, 3) have claimed that there is only one signal, a mitogenic signal, receptors acting merely as passive focusing devices to localize the antigen on specific cells where it delivers a mitogenic signal resulting in differentiation to an antibody-producing cell. This model rests primarily on the demonstration that at high concentration all T-independent antigens they have tested are mitogenic for B cells (4-6). Compatible with this hypothesis are the observations that hydrolysis of lipopolysaccharide (LPS) to remove the ester- linked fatty acids of the mitogenic lipid A component abrogates its mitogenic (7,8) activity as well as its ability, when substituted with the TNP hapten, to induce a T-independent anti- TNP response (9). However, alkali treatment of LPS, although not changing its antigenic component (8), may also modify the molecule physically or chemically which could account for loss of immunogenic properties (10). We therefore investigated other reagents which interact with LPS in a more chemically defined manner in an effort to clarify the relationship between the mitogenic and immunogenic properties of this molecule. Polymyxin B (PB) is one of a family of cyclic peptide antibiotics which are bactericidal for most gram-negative bacteria. It prevents the lethal endotoxic activity of LPS (11, 12) and changes the physical structure of LPS (13). We report here that low doses of PB added to cultures of mouse spleen cells inhibit the mitogenic activity of TNP-LPS, a T- independent antigen, and native LPS, but do not suppress the immune response to TNP-LPS. PB interacts with TNP-LPS and LPS causing a physical change in the molecule. In addition, polymyxin-treated LPS is no longer mitogenic. These results suggest a dissociation between the mitogenic and immunogenic properties of TNP-LPS.
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PMID:Dissociation between mitogenicity and immunogenicity of TNP-lipopolysaccharide, a T-independent antigen. 16 59

Polymyxin B, which is a basic polypeptide produced by various strains of Bacillus Polymyxa, has previously been shown to prevent the lethal effect of LPS and to neutralize the Schwartzmann reaction. In this study we have investigated the interactions between polymyxin B and lipopolysaccharide (LPS) and hapten LPS conjugates. Polymyxin B was found to suppress mitogenicity of LPS and also to inhibit immunogenicity of the hapten conjugate 4-hydroxy-3,5-dinitrophenacetyl (NNP)-LPS. Inhibition was not due to interference with the expression of NNP determinants nor to cross-reactivity between PB and the hapten. Since mitogenicity and immunogenicity decreased in parallel, we conclude that B-cell activation in specific thymus independent responses does not take place in the absence of a nonspecific (non-Ig-mediated) signal.
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PMID:Association between mitogenicity and immunogenicity of 4-hydroxy-3,5-dinitrophenacetyl-lipopolysaccharide, a T-independent antigen. 17 23

Activation of mononuclear cell tissue factor was examined utilizing lipopolysaccharides obtained from wild-type and both Rc and Re mutants of Salmonella typhimurium. Wild-type (smooth) lipopolysaccharide, galactose-deficient (Rc) lipopolysaccharide, heptose-deficient (Re) lipopolysaccharide, and lipid A preparations were all active in their ability to generate tissue factor activity in human mononuclear cells grown in tissue culture. Polymyxin B has been reported to prevent some of the lethal effects of endotoxin in vivo, and the drug reportedly binds to the 2-keto-3-deoxyoctulosonate-lipid A region of the lipopolysaccharide molecule. Polymyxin B was effective in inhibiting the tissue factor generating activity of wild-type lipopolysaccharide, Re lipopolysaccharide, and lipid A in a dose-dependent fashion. Treatment of lipid A preparations with mild alkali abolished the ability of these preparations to activate tissue factor in cells. Analogous to many of the other biologic properties of lipopolysaccharide, tissue factor activation in human mononuclear cells appears to depend upon the integrity of the lipid A portion of the molecule.
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PMID:Structural features of Salmonella typhimurium lipopolysaccharide required for activation of tissue factor in human mononuclear cells. 19 73

Events associated with endotoxin-induced mitogenesis in murine spleen cells were investigated. Commitment to deoxyribonucleic acid (DNA) synthesis, the onset of DNA synthesis, and phases of cell cycle were timed. Increased levels of DNA synthesis in murine spleen cells stimulated with endotoxin were observed 12 to 16 h after the addition of the mitogen. The total cell cycle time of stimulated B-cells was 11 to 14 h. The S-phase was 8 h. The G2-phase was 1 h, and the combined M-plus G1-phase of cycling cells was 2 to 5 h. A 1- to 4-h exposure to lipopolysaccharide elicited a significant increase in DNA synthesis. Progressively longer exposures to lipopolysaccharide, up to 24 h, produced further increases in first-cycle DNA synthesis. Polymyxin B, when added with endotoxin to cultures from the outset, inhibited first-cycle DNA synthesis. However, if addition of the antibiotic was delayed, progressive increases in first-cycle dna synthesis were observed. These data indicate a heterogeneity among B-cells in their responsiveness to endotoxin.
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PMID:Commitment to deoxyribonulceic acid synthesis and the cell cycle in endotoxin-stimulated murine spleen cells. 19 18

Polymyxins are known to be inhibitors of certain polyclonal B cell activators such as lipopolysaccharide and dextransulphate. However, increased specific responses to hapten-coupled mitogens have been reported after the addition of polymyxins to superoptimal conjugate doses. In this paper we have studied the effect of polymyxin B on superoptimal polyclonal doses of lipopolysaccharide. Results similar to those reported for hapten-lipopolysaccharide conjugates were obtained. Polymyxin B was also found to exert adjuvant properties for a primary immune response to sheep erythrocytes and to be a thymus-independent antigen.
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PMID:B-cell activating properties of polymyxin B. 20 83

The peptide antibiotic Polymyxin B (PMB) binds to bacterial endotoxin (lipopolysaccharide, LPS). We prepared covalent conjugates of PMB and horseradish peroxidase (HRP) by periodation of HRP-linked oligosaccharides followed by direct condensation with PMB. In addition we prepared monoclonal antibodies (Mabs) to PMB. The PMB-HRP conjugates and anti-PMB Mabs were used to study in ELISA the binding of PMB to LPS from Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. In addition, PMB-HRP was used to quantify lipid A in ELISA, and to stain gram-negative bacteria histochemically. For the study of PMB-LPS interaction, PMB-HRP proved to be superior to the anti-PMB Mabs. PMB-HRP conjugates are useful general probes to detect or measure lipid A and LPS of various species using very simple methods and to stain bacteria, and they may obviate the need for many specific antisera. Thus, PMB-HRP conjugates are useful probes for endotoxin research.
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PMID:Polymyxin B-horseradish peroxidase conjugates as tools in endotoxin research. 148 86

Overgrowth of Gram-negative bacteria as a result of total parenteral nutrition (TPN) and bowel rest could be responsible for the release of a variety of hepatotoxic substances such as endotoxin or tumor necrosis factor (TNF) and the ensuing TPN-associated liver function derangements. Polymyxin B is an effective antimicrobial agent as well as a blocking agent for endotoxin (lipopolysaccharide) activity and TNF production. In the present study we compared the oral and intravenous effects of polymyxin in rats receiving TPN in an attempt to define these two possible mechanisms of action of polymyxin on TPN-associated hepatic steatosis. Both oral, as well as intravenous polymyxin B, significantly reduced total hepatic fat and triglyceride accumulation in TPN rats, more so in the intravenous group exhibiting close to control levels. Both polymyxin-treated groups exhibited significantly lower Gram-negative bacterial counts in the cecum, with the oral group exhibiting a lower count than the IV group. The spontaneous production of TNF by peritoneal macrophages was markedly increased in rats receiving TPN and very close to being undetected in both groups receiving TPN and polymyxin. We believe polymyxin B protects the liver during TPN by both its antimicrobial effect which prevents overgrowth of gut Gram-negative bacteria and the subsequent translocation of endotoxin, and by its specific antilipopolysaccharide activity which, in the present study, completely abolished hepatic steatosis and TNF production during TPN.
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PMID:Polymyxin B reduces total parenteral nutrition-associated hepatic steatosis by its antibacterial activity and by blocking deleterious effects of lipopolysaccharide. 149 9

Lyme disease refers to the multisymptomatic illness in humans which results from infection with the tick-borne spirochete Borrelia burgdorferi. The white-footed mouse is the major reservoir for B. burgdorferi and, upon infection, certain inbred mice develop symptoms similar to those reported in human disease. Sonicated preparations of washed spirochetes were found to have potent mitogenic activity when cultured with lymphocytes from naive C57BL/6, C3H/HeJ, or BALB/c mice. The activity of the B. burgdorferi sonicate was approximately fourfold greater than that of a similarly prepared Escherichia coli sonicate. Polymyxin B efficiently inhibited the mitogenic activity of the E. coli sonicate but only slightly inhibited that of the B. burgdorferi sonicate, suggesting that a lipid A-containing lipopolysaccharide was not responsible for the B. burgdorferi activity. Kinetic analysis indicated peak proliferation at 2 to 3 days of culturing, suggesting polyclonal activation. B- and T-lymphocyte depletion experiments indicated that the major cell type responding to the B. burgdorferi mitogen was the B lymphocyte. This mitogen stimulated murine B cells not only to proliferate but also to differentiate into antibody-secreting cells, as demonstrated by the production of immunoglobulin by stimulated splenocytes. Furthermore, the sonicated preparation stimulated the B-cell tumor line CH12.LX to secrete immunoglobulin in the absence of accessory cells. B. burgdorferi also stimulated interleukin-6 production in splenocyte cultures. The observation that B. burgdorferi can stimulate activation of and immunoglobulin production by normal B lymphocytes may directly reflect on the development of arthritis associated with persistent infection by this organism.
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PMID:Demonstration of a B-lymphocyte mitogen produced by the Lyme disease pathogen, Borrelia burgdorferi. 173 Apr 76

Polymyxin B, when bound to a polystyrene fiber (PMX-F), has been used experimentally as an extracorporeal blood filter to reduce serum lipopolysaccharide levels, which are believed to be responsible for physiologic alterations in the septic state. To validate our theory that a combination of PMX-F, systemic antibiotics, and immune stimulation would improve survival, 78 rats were given intravenous doses of Escherichia coli (range, 4.6 to 6.2 X 10(8) colony-forming units/ml). They were then randomized into groups receiving either systemic gentamicin (n = 10); pretreatment with muramyl dipeptide (n = 11); or extracorporeal hemoperfusion through either a sham column (n = 8), PMX-F-packed column with systemic gentamicin (n = 8); or PMX-F-packed column with systemic gentamicin and muramyl dipeptide pretreatment (n = 8). Thirty-three control rats received no treatment. Sham hemoperfusion (13%) and control (21%) rats had the lowest survival rate, although increased improvement was noted in rats treated with gentamicin (30%) or the combination of PMX-F filtration and gentamicin (50%). The most significant improvements occurred in rats pretreated with muramyl dipeptide (53%) and in rats treated with a combination of PMX-F, gentamicin, and muramyl dipeptide (88%). These data show that lipopolysaccharide filtration and nonspecific immune stimulation are additive to antibiotic therapy and are useful as adjunctive measures in the multimodal treatment of experimental gram-negative bacterial infection.
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PMID:Endotoxin filtration and immune stimulation improve survival from gram-negative sepsis. 192 67


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