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)

Lactoferrin (Lf) has been found in most biological fluids including amniotic fluid and cervical mucoids in pregnant women, and released from neutrophils in response to the inflammation. As Lf possesses antimicrobial properties, it is widely considered to be an important component of the host defence against microbial infections. It is known that premature labor is caused by amniotic infection with the increase of prostaglandin production. High concentration of the inflammatory cytokines: interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha) in the amniotic fluid has been known. However, changes of Lf in amniotic fluid with infection has not been reported. In the present study, Lf concentrations in amniotic fluid were measured under the intra-uterine infections state and the biological significance of Lf was investigated. The effects of Lf on the IL-6 and IL-6mRNA production in cultured amnion cells were also investigated. The concentrations of Lf and IL-6 in amniotic fluid with CAM were 8.76 +/- 0.65 micrograms/ml and 6.92 +/- 4.88 ng/ml (n = 28) respectively and both were significantly higher (p < 0.01) than those without CAM [0.86 +/- 0.81 microgram/ml and 0.34 +/- 0.25 ng/ml (n = 31)]. Significant positive correlation (r = 0.91, p < 0.01) between Lf and IL-6 levels in amniotic fluid was found. IL-6 production induced by lipopolysaccharide (LPS) (100 ng/ml) in cultured amnion cells was significantly inhibited (p < 0.05) under the physiological concentration of Lf in amnion. Total RNA was extracted from the amniotic cells by guianizine solution. RT-PCR procedure and product analysis were performed from one microgram aliquote of total RNA. beta-actin was used as an international standard and c-DNA samples were followed by 30 cycles of PCR. RT-PCR product of IL-6 mRNA was detected by Southern hybridization. Expression of IL-6 mRNA was inhibited by the addition of Lf. From the results, the possibility that Lf might suppress amniotic IL-6 production under the condition of amniotic infection is suggested. It is also suggested that Lf might act as self defence mechanism from intra-uterine infection.
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PMID:Lactoferrin and interleukin-6 interaction in amniotic infection. 978 69

The aim of this study was to investigate an effect of oral treatment of rats with bovine lactoferrin (BLF) on carrageenan-induced inflammation. Rats were given 5 oral doses of BLF (10 mg each) on alternate days and 24 h after the last dose a carrageenan inflammation was induced in the hind foot. Control rats were given 0.9% natrium chloride (NaCl) or bovine serum albumin (BSA). The magnitude of the reaction was measured after 2 h (optimal response) and expressed as an increase of the foot pad thickness in milimeters. The evaluation of BLF effects on carrageenan reaction was supplemented by determination of the ability of spleen cell cultures to produce interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-alpha) upon lipopolysaccharide (LPS) induction using bioassays. The results revealed an inhibition of the carrageenan-induced inflammation in BLF-treated rats by 50 and 40% as compared to NaCl and BSA control groups, respectively. The inhibition was also associated with a substantial decrease in the ability of splenocytes to produce IL-6 in BLF-treated rats (94 and 83% as compared to NaCl- and BSA-treated groups). The LPS-induced TNF-alpha production was also decreased, although to a lesser degree (48 and 35%, respectively). The decreased ability of spleen cells to produce inflammatory cytokines in BLF-treated rats indicates that hyporeactivity of the immune system cells may be the basis for the inhibition of carrageenan-induced inflammation.
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PMID:Oral treatment of rats with bovine lactoferrin inhibits carrageenan-induced inflammation; correlation with decreased cytokine production. 988 15

Endotoxin (lipopolysaccharide [LPS]) is the major pathogenic factor of gram-negative septic shock, and endotoxin-induced death is associated with the host overproduction of tumor necrosis factor alpha (TNF-alpha). In the search for new antiendotoxin molecules, we studied the endotoxin-neutralizing capacity of a human lactoferrin-derived 33-mer synthetic peptide (GRRRRSVQWCAVSQPEATKCFQWQRNMRKVRGP; designated LF-33) representing the minimal sequence for lactoferrin binding to glycosaminoglycans. LF-33 inhibited the coagulation of the Limulus amebocyte lysate and the secretion of TNF-alpha by RAW 264.7 cells induced by lipid A and four different endotoxins with a potency comparable to that of polymyxin B. The first six residues at the N terminus of LF-33 were critical for its antiendotoxin activity. The endotoxin-neutralizing capacity of LF-33 and polymyxin B was attenuated by human serum. Coinjection of Escherichia coli LPS (125 ng) with LF-33 (2.5 microg) dramatically reduced the lethality of LPS in the galactosamine-sensitized mouse model. Significant protection of the mice against the lethal LPS challenge was also observed when LF-33 (100 microg) was given intravenously after intraperitoneal injection of LPS. Protection was correlated with a reduction in TNF-alpha levels in the mouse serum. These results demonstrate the endotoxin-neutralizing capability of LF-33 in vitro and in vivo and its potential use for the treatment of endotoxin-induced septic shock.
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PMID:Neutralization of endotoxin in vitro and in vivo by a human lactoferrin-derived peptide. 1002 82

Lactoferrin (LF) has been found in most biological fluids including amniotic fluid and cervical mucus in pregnant women and is released from neutrophils in response to inflammation. It is an important component of the host defence against microbial infections due to its antimicrobial properties. Premature labour is caused by amniotic infection and high concentrations of inflammatory cytokines in amniotic fluid with infection are well established. In the present study, LF levels of intrauterine infection in amniotic fluid were measured and the biological significance of LF was investigated. The effects of LF on IL-6 production in cultured amnion cells were also investigated. The concentrations of LF and IL-6 in amniotic fluid with chorioamnionitis (CAM) were 8.76+/-0.65 microg/ml and 6.92+/-4.88 ng/ml (n = 28), respectively, and both were significantly higher (P<0.01) than those without CAM (0.86+/-0.81 microg/ml and 0.34+/-0.25 ng/ml; n = 31). LF and IL-6 levels were significantly higher (P<0.01) with CAM. A significant positive correlation between LF and IL-6 levels in amniotic fluid was found (r = 0.91, P<0.01). To our knowledge, this was the first study of its kind, which shows that IL-6 production induced by lipopolysaccharide in cultured cells was significantly inhibited below physiological concentration of LF in the amnion. In addition, the immunohistochemical localization of LF in fetal membranes was investigated. In the fetal membranes with CAM, strong positive staining was observed in amniotic and chorionic membranes, with leucocyte migration, while weak staining was observed in membranes without CAM. These results show conclusively that LF suppresses amniotic IL-6 production under the conditions of intrauterine infection.
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PMID:Amniotic fluid lactoferrin in intrauterine infection. 1019 38

Lactoferrin (LF) is a glycoprotein that exerts both bacteriostatic and bactericidal activities. The interaction of LF with lipopolysaccharide (LPS) of gram-negative bacteria seems to play a crucial role in the bactericidal effect. In this study, we evaluated, by means of an enzyme-linked immunosorbent assay, the binding of biotinylated LF to the S (smooth) and R (rough) (Ra, Rb, Rc, Rd1, Rd2, and Re) forms of LPS and different lipid A preparations. In addition, the effects of two monoclonal antibodies (AGM 10.14, an immunoglobulin G1 [IgG1] antibody, and AGM 2.29, an IgG2b antibody), directed against spatially distant epitopes of human LF, on the LF-lipid A or LF-LPS interaction were evaluated. The results showed that biotinylated LF specifically binds to solid-phase lipid A, as this interaction was prevented in a dose-dependent fashion by either soluble uncoupled LF or lipid A. The binding of LF to S-form LPS was markedly weaker than that to lipid A. Moreover, the rate of LF binding to R-form LPS was inversely related to core length. The results suggest that the polysaccharide O chain as well as oligosaccharide core structures may interfere with the LF-lipid A interaction. In addition, we found that soluble lipid A also inhibited LF binding to immobilized LPS, demonstrating that, in the whole LPS structure, the lipid A region contains the major determinant recognized by LF. AGM 10.14 inhibited LF binding to lipid A and LPS in a dose-dependent fashion, indicating that this monoclonal antibody recognizes an epitope involved in the binding of LF to lipid A or some epitope in its close vicinity. In contrast, AGM 2.29, even in a molar excess, did not prevent the binding of LF to lipid A or LPS. Therefore, AGM 10.14 may represent a useful tool for neutralizing selectively the binding of LF to lipid A. In addition, the use of such a monoclonal antibody could allow better elucidation of the consequences of the LF-lipid A interaction.
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PMID:Lactoferrin-lipid A-lipopolysaccharide interaction: inhibition by anti-human lactoferrin monoclonal antibody AGM 10.14. 1045 14

The aim of this study was to investigate effects of human lactoferrin (hLF) with regard to LFA-1 expression on unstimulated and lipopolysaccharide (LPS)-activated human peripheral blood mononuclear cells (PBMC). The investigations were carried out on 30 healthy volunteers, males and females, 24-58 years old. We found that hLF, at an optimal dose of 5 microg/ml/10(6) cells in 24-hour culture, exerted regulatory effects on LFA-1 expression, depending on distribution of this molecule on cells in control cultures and on the effects of LPS. First, we revealed several patterns of LFA-1 distribution and density of this marker among studied individuals. The effects of LPS and hLF on LFA-1 expression patterns were differential. LFA-1 expression was stimulated by individual actions of LPS or hLF, additive or synergistic effects of both factors, it could be also inhibited by hLF alone or in combination with LPS. In about one third of cases no significant effects of LPS or hLF on LFA-1 expression were seen. Removal of monocytes from the PBMC population diminished LFA-1 expression in control cultures and abolished LPS- or hLF-elicited changes. The regulatory effects of hLF were also blocked by treatment of PBMC cultures with anti-tumor necrosis factor alpha (TNF-alpha) antibodies. Taken together, the data showed that hLF and LPS had immunoregulatory properties with respect to LFA-1 expression on human PBMC and that these actions were mediated by monocytes and TNF-alpha.
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PMID:Regulatory effects of lactoferrin and lipopolysaccharide on LFA-1 expression on human peripheral blood mononuclear cells. 1048 75

One of the biological functions of lactoferrin is the modulation of the host defense systems, including cytokine production and immune responses. We have tested the effect of lactoferrin on the productions of tumor necrosis factor-alpha and nitric oxide in some cells. Lactoferrin itself did not induce either tumor necrosis factor-alpha production or nitric oxide production, but lipopolysaccharide-stimulated tumor necrosis factor-alpha production of macrophages and monocytes were inhibited by lactoferrin treatment combined with stimulant. The induction of nitric oxide synthesis in stimulated macrophages and vascular smooth muscle cells was not affected by the lactoferrin.
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PMID:Effect of lactoferrin on the production of tumor necrosis factor-alpha and nitric oxide. 1058 Sep 98

Lactoferrin (LFR) plays an important role in the anti-microbial defense through iron binding, lipopolysaccharide binding and immunomodulation. In this study, we demonstrate that bovine LFR specifically inhibits the hemolytic activity of listeriolysin O (LLO) produced by Listeria monocytogenes. The hemolytic activity of LLO was completely inhibited in the presence of bovine LFR that was highly purified on two cation-exchange columns, whereas that of streptolysin O or perfringolysin O was not inhibited at all. A rabbit anti-LFR antibody canceled this inhibitory activity of bovine LFR. Although human transferrin exhibits 62% amino acid identity with bovine LFR, human apo-transferrin could not inhibit LLO-induced hemolysis. An increase in the concentration of FeCl3 or the Fe3+-saturation of bovine LFR, however, slightly reduced its inhibition of the hemolysis. The inhibitory activity of bovine LFR was dependent on pH, since it was observed under neutral and alkali conditions, but not under acidic conditions. These results suggest that the inhibition of LLO-induced hemolysis by bovine LFR is influenced by pH and iron ions, both of which may lead to conformational changes of LFR.
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PMID:Inhibition of listeriolysin O-induced hemolysis by bovine lactoferrin. 1059 21

A synthetic peptide (23 residues) that includes the antibacterial and lipopolysaccharide-binding regions of human lactoferricin, an antimicrobial sequence of lactoferrin, was used to study its action on cytoplasmic membrane of Escherichia coli 0111 and E. coli phospholipid vesicles. The peptide caused a depolarization of the bacterial cytoplasmic membrane, loss of the pH gradient, and a bactericidal effect on E. coli. Similarly, the binding of the peptide to liposomes dissipated previously created transmembrane electrical and pH gradients. The dramatic consequences of the transmembrane ion flux during the peptide exposure indicate that the adverse effect on bacterial cells occurs at the bacterial inner membrane.
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PMID:Permeabilizing action of an antimicrobial lactoferricin-derived peptide on bacterial and artificial membranes. 1062 10

The hypothesis that lactoferrin protects mice against lethal effects of bacterial lipopolysaccharide (LPS) is the subject of experimental investigations described in this article. Lipopolysaccharide is a powerful toxin produced by gram negative bacteria that when injected into humans or experimental animals reproduce many of the pathophysiologic and immune responses caused by live bacteria. Lactoferrin administered intraperitoneally 1 hr prior to injection of LPS significantly enhanced the survival of mice, reducing LPS-induced mortality from 83.3% to 16.7%. Changes in locomotor and other behavioral activities resulting from LPS injection were not present in mice treated with lactoferrin. Also, histological examination of intestine revealed remarkable resistance to injury produced by LPS if mice were pretreated with lactoferrin. Severe villus atrophy, edema and epithelial vacuolation were observed in LPS-treated animals but not in lactoferrin-treated counterparts. Electrophysiological parameters were used to assess secretory and absorptive functions in the small intestine. In mice treated with LPS, transmural electrical resistance was reduced and absorption of glucose was increased. Lactoferrin treatment had no significant influence on basal electrophysiological correlates of net ion secretion or glucose absorption nor on changes induced by LPS. Collectively, these results suggest that lactoferrin attenuates the lethal effect of LPS and modulates behavioral and histopathological sequela of endotoxemia.
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PMID:Lactoferrin protects gut mucosal integrity during endotoxemia induced by lipopolysaccharide in mice. 1070 62


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