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)

During infection or inflammation, cells of the blood vessel wall, such as endothelial cells (EC) and smooth muscle cells (SMC), contribute to the regulation of the immune response by production of cytokines or expression of adhesion molecules. Little is known about the mechanism(s) involved in the stimulation of vascular cells by endotoxin (lipopolysaccharide [LPS]). As reported previously, LPS antagonists reduce LPS-induced cytokine production or adhesion in vitro specifically, suggesting a specific LPS recognition mechanism. We thus investigated the role of CD14 for stimulation of vascular SMC by LPS. Complement-fixing antibodies directed against CD14 (LeuM3, RoMo I, or Mo2) lysed monocytes but failed to mediate lysis of EC or SMC, indicating the lack of endogenous membrane CD14 in vascular cells. In addition, we did not detect expression of CD14 protein on EC and SMC in cell sorting analysis or cell immunoassay experiments. These observations are in line with our finding that a CD14 probe did not hybridize with mRNA or EC or SMC in Northern (RNA) blot experiments, although it hybridized well with monocyte-derived mRNA. We obtained the same results with the much more sensitive reverse transcription-PCR. Since the vascular SMC did not express endogenous CD14, we investigated the role of human serum-derived soluble CD14 (sCD14) for activation of SMC by LPS. In medium containing human serum, anti-CD14 antibodies inhibited activation of SMC by LPS. In contrast, the same antibodies did not inhibit activation of cells cultured in medium containing fetal calf serum. SMC cultured in sCD14-depleted medium responded 1,000-fold less to LPS than cells cultured in presence of sCD14. Reconstitution of sCD14-depleted serum or supplementation of serum-free medium with recombinant CD14 restored the capacity of the cells to respond to LPS. These results show that specific activation of vascular SMC by LPS does not involve binding to endogenous membrane CD14, but that the activation of vascular SMC by LPS is mediated to a great extent by serum-derived sCD14.
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PMID:Endotoxin activates human vascular smooth muscle cells despite lack of expression of CD14 mRNA or endogenous membrane CD14. 753 23

We have previously isolated a lipopolysaccharide (LPS)-resistant mutant (named LR-9) of a cultured macrophage-like cell line, J774.1. This mutant had defective LPS binding [Hara-Kuge, S., Amano, F., Nishijima, M., and Akamatsu, Y. (1990) J. Biol. Chem. 265, 6606-6610]. In this study, we found that: (1) LPS-binding to parental J774.1 cells was dependent on a serum factor with a molecular weight of about 60 kDa, probably LPS binding protein (LBP); (2) LPS-binding to J774.1 cells was markedly reduced by treating the cells with phosphatidylinositol-specific phospholipase C (PI-PLC); (3) mutant LR-9 cells were defective in LPS-binding even in the presence of serum; (4) LR-9 cells lacked CD14 protein on flow cytometric and immunoblot analyses, but retained normal CD14 mRNA levels on RNA blot analysis; (5) small amounts of LPS (1 to 10 ng/ml) activated J774.1, but not LR-9 cells, to secrete tumor necrosis factor-alpha and to release arachidonate metabolites, whereas both J774.1 and LR-9 were activated by large concentrations of LPS (100 to 1,000 ng/ml). These results provide genetic evidence that CD14 molecules in J774.1 cells play a crucial role in LPS-binding and in LPS-triggered signal transduction, and indicate that large amounts of LPS can activate J774.1 cells without the participation of CD14 molecules.
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PMID:Identification of a biochemical lesion, and characteristic response to lipopolysaccharide (LPS) of a cultured macrophage-like cell mutant with defective LPS-binding. 753 58

In vitro studies have previously shown that the myelomonocytic differentiation antigen CD14 is a receptor for a complex consisting of lipopolysaccharide (LPS) and LPS-binding protein. To investigate the role of CD14 in vivo and its relationship to induction of LPS-induced endotoxin shock, transgenic mice expressing human CD14 were produced. These mice express human CD14 strongly on the surface of their monocytes, neutrophils, and Thy-1(+) lymphocytes and are hypersensitive to LPS, as evidenced by their increased susceptibility to endotoxin shock. These results document the importance of CD14 in vivo as a primary mediator of this lethal syndrome. Furthermore, these mice provide an important model for testing the therapeutic effects of agents directed specifically against the human, as opposed to the murine, CD14 protein in preventing LPS-induced endotoxin shock.
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PMID:Transgenic mice expressing human CD14 are hypersensitive to lipopolysaccharide. 768 94

Here we show that lipopolysaccharide (LPS) induction of glial inducible nitric oxide synthase (iNOS) requires membrane (m) and soluble (s) forms of CD14. In glial cell cultures, an anti-rat CD14 monoclonal antibody detected CD14 protein in whole cells and cell lysates, and reduced LPS-dependent iNOS expression. Glial cells and normal brain tissue expressed CD14 mRNA, as revealed by isolation of a rat CD14 clone (rCD14) from an astrocyte cDNA library and RT-PCR analysis. Finally, serum the ED(50) of LPS required for glial iNOS expression, and antibodies against sCD14 blocked the potentiating effect of serum.
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PMID:CD14 mediate endotoxin induction of nitric oxide synthase in cultured brain glial cells. 859 86

The human monocytic cell lines MUTZ-3 and MONO-MAC-6 express the lipopolysaccharide (LPS) receptor CD14. Paralleling the situation in peripheral blood monocytes (PBMo), recombinant human interleukin-4 (IL-4) down-regulated the expression of CD14 on the cell surface of MUTZ-3, but not that of MONO-MAC-6 cells. In addition, preincubation with IL-4 prevented the LPS-induced up-regulation of IL-1 beta mRNA levels in MUTZ-3, but not in MONO-MAC-6 cells. We examined whether the differential responsiveness of the cell lines was due to the missing expression of the IL-4 receptor (IL-4R) alpha or gamma c chain in MONO-MAC-6 cells. Flow cytometric and immunoprecipitation analysis revealed expression of both IL-4R chains in both cell lines. In addition, short-term stimulation with IL-4 induced tyrosine-phosphorylation of the gamma c chain. As both cell lines also expressed signal transducer and activator of transcription 6 (STAT 6), our data suggested that the differential reaction patterns of MUTZ-3 and MONO-MAC-6 cells were not due to a generally defective IL-4R complex. Interestingly, long-term (48 hr) treatment with LPS rendered MONO-MAC-6 cells sensitive to IL-4. LPS up-regulated expression of monocyte-specific esterase (MSE) mRNA as well as CD14 protein in MONO-MAC-6 cells; both effects were inhibited by IL-4. This stimulation was not paralleled by an increase of IL-4R mRNA or protein expression supporting the above hypothesis of a constitutively present and active IL-4R. We discuss possible causes for the differential reaction patterns of MUTZ-3 and MONO-MAC-6 cells to IL-4.
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PMID:MUTZ-3, a monocytic model cell line for interleukin-4 and lipopolysaccharide studies. 901 29

Gut-derived endotoxins (lipopolysaccharide, LPS) are believed to contribute to alcohol-induced liver disease (ALD) by stimulating Kupffer cells, the resident liver macrophages, to release proinflammatory cytokines. This activation is largely mediated by CD14, a high-affinity membrane-anchored receptor for LPS. We observed, by chemiluminescence-enhanced detection, an increase in immunoreactive CD14 protein in Kupffer cells isolated from rats treated with ethanol for 2 weeks. Immunocytofluorescence experiments confirmed that this increase was confined to the membranes of Kupffer cells from the alcohol-treated rats. The increase was regulated pretranslationally: a 3-fold elevation (p < 0.01) in the hepatic level of CD14 mRNA was observed. The marked increase in CD14 expression suggests a new mechanism by which alcohol increases the LPS-mediated cytokine signaling by the liver macrophages, thus promoting the interaction between alcohol and endotoxins in the development of liver damage.
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PMID:Alcohol-induced expression of the CD14 endotoxin receptor protein in rat Kupffer cells. 939 30

Studies were undertaken to examine hepatocyte CD14 expression during endotoxemia. Our results show that lipopolysaccharide (LPS) treatment in vivo caused a marked upregulation in CD14 mRNA and protein levels in rat hepatocytes. Detectable increases in mRNA were seen as early as 1.5 h after LPS treatment; these increases peaked at 20-fold by 3 h and returned to baseline levels by 24 h. In situ hybridization localized the CD14 mRNA expression to hepatocytes both in vitro and in vivo. Increases in hepatic CD14 protein levels were detectable by 3 h and peaked at 12 h. Hepatocytes from LPS-treated animals expressed greater amounts of cell-associated CD14 protein, and more of the soluble CD14 was released by hepatocytes from LPS-treated rats in vitro. The increases in hepatocyte CD14 expression during endotoxemia occurred in parallel to increases of CD14 levels in plasma. To provide molecular identification of the hepatocyte CD14, we cloned the rat liver CD14 cDNA. The longest clone consists of a 1,591-bp insert containing a 1,116-bp open reading frame. The deduced amino acid sequence is 372 amino acids long, has 81.8 and 62.8% homology to the amino acid sequences of mouse and human CD14, respectively, and is identical to the rat macrophage CD14. The expressed CD14 protein from this clone was functional, as indicated by NF-kappaB activation in response to LPS and fluorescein isothiocyanate-LPS binding in CHO cells stably transfected with rat CD14. A nuclear run-on assay showed that CD14 transcription rates were significantly increased in hepatocytes from LPS-treated animals, indicating that the upregulation in CD14 mRNA levels observed in rat hepatocytes after LPS treatment is dependent, in part, on increased transcription. In vitro and in vivo experiments indicated that interleukin-1beta and/or tumor necrosis factor alpha participate in the upregulation of CD14 mRNA levels in hepatocytes. Our data indicate that hepatocytes express CD14 and that hepatocyte CD14 mRNA and protein levels increase rapidly during endotoxemia. Our observations also support the idea that soluble CD14 is an acute-phase protein and that hepatocytes could be a source for soluble CD14 production.
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PMID:Expression of CD14 by hepatocytes: upregulation by cytokines during endotoxemia. 978 8

CD14, a glycoprotein that binds bacterial lipopolysaccharide, plays a critical role in the inflammatory response to infection by gram-negative bacteria. Studies were undertaken to determine whether cyclic adenosine monophosphate (cAMP) regulates CD14 expression in macrophages. Incubation of RAW 264.7 cells with 8-Br-cAMP resulted in a significant increase in steady-state CD14 mRNA levels. The increase in mRNA levels was also associated with both cell-associated and soluble CD14 protein. H89 completely blocked the 8-Br-cAMP-induced CD14 mRNA up-regulation. There was no change in CD 14 mRNA half-life in the presence of 8-Br-cAMP. The CD14 gene transcription rate was increased about twofold after exposure to 8-Br-cAMP. cAMP-dependent increases in CD14 mRNA were also observed in rat peritoneal macrophages, demonstrating that this is an authentic response of mature macrophages. This study provides evidence that cAMP and protein kinase A are important regulators of CD14 expression in macrophages.
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PMID:cAMP induces CD14 expression in murine macrophages via increased transcription. 1085 64

CD14 is a leukocyte surface molecule expressed on monocytes but not on lymphocytes. Recently, CD14 molecule was demonstrated to function as a receptor for endotoxin. CD14 specific monoclonal antibody (MAb), therefore, can be used to identify monocytes and study the host defense mechanism to bacterial endotoxin. To produce MAb against CD14 protein, in this study cDNA encoding CD14 protein and COS cell expression systems were used to prepare CD14 expressing COS cells. The CD14 transfectants were then used as antigen for mouse immunization. The spleen cells of the immunized mouse were then fused with myeloma cells by conventional hybridoma technique. By using this strategy, 5 hybridroma clones secreting antibody specific for CD14 molecule were generated within one fusion. The generated CD14 MAbs were strongly positive with monocytes, weakly positive with neutrophils but negative with lymphocytes. In addition, the generated CD14 MAb blocked the binding of lipopolysaccharide (LPS) to the CD14 molecules. These CD14 MAbs could be used to enumerate peripheral blood monocytes as well as using referent CD14 MAb. We, therefore, introduce an alternative method for preparation of antigen for production of monoclonal antibody. This type of antigen is a very effective antigen for the production of monoclonal antibodies against cell surface molecules.
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PMID:Production of anti-CD14 monoclonal antibodies using CD14 expressing COS cells as immunizing antigen. 1254 58

Saliva contains a number of proteins and glycoproteins that protect oral tissues, but little is known about the role of human saliva in innate immunity. Here we showed that human major salivary gland cells constitutively expressed a bacterial pattern recognition receptor, CD14, by immunohistochemistry. Human salivary gland cells in culture express CD14 mRNA and a 55-kDa CD14 protein in, but not on the cells, and secrete a soluble form with the same molecular mass. Human whole saliva contains a 55-kDa CD14, and the concentration of parotid saliva was 10-fold higher than whole saliva, which is comparable to that of serum CD14. Levels of CD14 in unstimulated whole and parotid saliva were unchanged before and after a meal and between unstimulated and stimulated saliva, indicating that saliva CD14 is constitutively secreted into the oral cavity. In contrast, lipopolysaccharide (LPS)-binding protein was below the detectable level. The saliva CD14 is functionally active in that it mediated the activation of CD14-lacking intestinal epithelial cells by LPS in a Toll-like receptor 4-dependent manner. These results suggested that saliva CD14 is important for the maintenance of oral health and possibly intestinal homeostasis.
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PMID:Constitutive expression of a bacterial pattern recognition receptor, CD14, in human salivary glands and secretion as a soluble form in saliva. 2035 76


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