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)

The human MONO-MAC-6 cell line expresses the monocyte-associated differentiation markers CD14 and monocyte-specific esterase (MSE) and can be stimulated by lipopolysaccharide (LPS) to produce high mRNA levels of monocyte-related cytokines. This similarity to human peripheral blood monocytes (PBMo) renders this cell line a promising model for studies of monocyte activation and differentiation. Interleukin-4 (IL-4) is known to act antagonistically to LPS during the activation process of PBMo, inhibiting the production of cytokines. Therefore, this study was designed to compare the effects of IL-4 and LPS on the expression of monocytic markers and tumor necrosis factor alpha (TNF alpha) mRNA on PBMo and the MONO-MAC-6 cell line. IL-4 inhibited the LPS-induced expression of TNF alpha mRNA in PBMo and downregulated the LPS receptor CD14 but it had no influence on MONO-MAC-6 cells regarding these parameters. However, upregulation of CD14 and MSE mRNA expression in the cell line by a 2-day incubation with LPS were inhibited by IL-4. This response to IL-4 after long-term treatment with LPS was seemingly contradictory to the missing reduction of TNF alpha mRNA expression after short-term incubation with LPS. Obviously long-term treatment with LPS made the cells responsive to IL-4. The increase in responsiveness was not due to IL-4 receptor (IL-4R) upregulation, as LPS did not influence the constitutive expression of the IL-4R.
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PMID:IL-4 inhibits the LPS-induced expression of CD14 and monocyte-specific esterase mRNA in MONO-MAC-6 cells. 752 93

We have investigated the interaction of soluble peptidoglycan (sPG), in comparison with lipopolysaccharide (LPS), with human mononuclear cells (MNC) by determining the capacity of sPG to induce interleukin-6 (IL-6) and IL-1 release. In addition, we investigated the modulation of their interaction by anti-CD14 monoclonal antibody and by partial structures of LPS. We found that sPG, like LPS, was able to induce IL-6 and IL-1 production by MNC. However, dose-response experiments revealed that at least 3,000 ng of sPG per ml was necessary for induction, whereas the optimal LPS concentration was 1 ng/ml. Anti-CD14 monoclonal antibody reduced sPG- and LPS-induced IL-6 and IL-1 production. Moreover, partial structures of LPS were able to reduce monokine production induced by sPG and LPS. We conclude that sPG constitutes, like LPS, an inflammatory cytokine inducer and that CD14 is involved in the activation of human monocytes not only by LPS but also by sPG.
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PMID:Soluble peptidoglycan-induced monokine production can be blocked by anti-CD14 monoclonal antibodies and by lipid A partial structures. 752 97

Marked elevation of transforming growth factor-beta 1 (TGF-beta 1) has been demonstrated clinically following injury and in sepsis. While alterations in the monocyte binding site (CD14) for the lipopolysaccharide (LPS)-lipopolysaccharide binding protein (LBP) complex have been noted with exposure to LPS, immune complexes, gamma-interferon, and IL-4, it is not known whether TGF-beta 1 can alter CD14 expression. To study the effect of TGF-beta 1 on monocyte CD14 expression, human leukocytes were isolated from healthy donors with discontinuous gradient centrifugation and incubated at 37 degrees C for 2 and 24 hr with increasing doses of purified human platelet TGF-beta 1. Monocytes were immunofluorescently stained with monoclonal antibodies recognizing CD14 and CD16. The cells were analyzed by flow cytometry. At 2 hr, 50 ng/ml TGF-beta 1 significantly lowered CD14 expression (51%, P = 0.043). At 24 hr, there was no significant difference between cells stimulated by TGF-beta 1 and control cells. To confirm that TGF-beta 1 was active at 24 hr, we examined levels of CD16. CD16 expression was increased by 10 ng/ml of TGF-beta 1. These observations suggest that high physiologic concentrations of TGF-beta 1 cause early monocyte suppression of CD14. Thus, CD14 may be marker for the transition of monocytes to macrophages and TGF-beta 1 may be responsible for the down-regulation of CD14 expression observed in monocytes obtained from septic patients.
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PMID:Transforming growth factor-beta 1 lowers the CD14 content of monocytes. 752 45

Several monoclonal antibodies directed against the human CD14 antigen have been established. We now report that the antibody My4, but not LeuM3, reacts with porcine monocytes. Among porcine peripheral blood mononuclear cells (PBMC), 14.6% of the cells stain with the CD14 antibody My4, which is similar to the percentage obtained with the antiporcine monocyte antibody 74-22-15. Two-colour immunofluorescence reveals that My4 and 74-22-15 antigens are coexpressed on the same cells, and cell sorter-purified My4+ cells exhibit the morphology of monocytes. Whole blood analysis (which also shows staining of granulocytes) reveals that the average percentage of My4+ monocytes amongst all leucocytes is 5.8% with 580 cells/microliters. Furthermore, porcine peritoneal macrophages (PM) and alveolar macrophages (AM), both stain for My4, with a four-fold lower level on AM. Treatment of cells with phosphatidylinositol-specific phospholipase C decreases My4 staining, but does not affect staining with antibody 74-22-15. Immunoprecipitation with the My4 antibody from surface labelled pig mononuclear cells demonstrates a 54 kDa band similar to human CD14, and Western blotting with pig serum demonstrates two bands similar to the alpha and beta forms of human soluble CD14. Finally, the My4 antibody is capable of blocking lipopolysaccharide- (LPS)-induced interleukin-6 production in isolated PBMC. These data show that the My4 antibody recognizes genuine CD14 on porcine monocytes and macrophages.
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PMID:The antibody MY4 recognizes CD14 on porcine monocytes and macrophages. 752 41

Previous research in our laboratory has shown that polymorphonuclear leukocytes (PMN) from neonates are not primed effectively in vitro with lipopolysaccharide (LPS) (from Escherichia coli 0111:B4) compared with priming of adult PMN. This finding led us to speculate that differences between neonatal and adult LPS receptors may account for the lower response by neonatal PMN to LPS. In these experiments, we investigated if CD14 or other LPS receptors contribute to the priming activity of PMN by LPS. We found that unprimed neonatal and adult PMN expressed similar numbers of CD14 (11.6 +/- 9.2 versus 18.6 +/- 2.7 fluorescence units [FlU]; P > 0.05) and LPS-binding sites (2.94 +/- 1.4 versus 4.94 +/- 0.79 FlU; P > 0.05). Monoclonal antibody against CD14 (MY4) did not significantly change the binding of LPS to adult unprimed PMN, suggesting that LPS receptors other than CD14 receptors are predominant on PMN. However, when PMN were pretreated with LPS (10 ng/ml) for 45 min at 37 degrees C, expression of CD14 on adult PMN increased to 33.8 +/- 4.9 FlU (P < 0.05 versus unprimed adult PMN) while that on neonatal PMN showed little change, increasing to 17.2 +/- 10.3 FlU (P > 0.05 versus unprimed neonatal PMN; P < 0.05 versus primed adult PMN). Furthermore, MY4 specifically blocked oxidative-radical production from PMN primed with LPS (10 ng/ml) compared with that from control PMN (P < 0.01). These studies suggest that LPS primes PMN by activating CD14 expression. We conclude that lower expression of CD14 or failure to up-regulate CD14 after LPS pretreatment contributes to the inability of neonatal PMN to be primed by LPS.
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PMID:Diminished priming of neonatal polymorphonuclear leukocytes by lipopolysaccharide is associated with reduced CD14 expression. 752 32

We have tested hypotheses relating lipoprotein structure to function as measured by the relative ability to neutralize endotoxin by comparing natural human lipoproteins, a chemically defined form of reconstituted high-density lipoprotein (R-HDL), and a lipid emulsion (Intralipid). The human whole-blood system was used as an in vitro model of lipopolysaccharide (LPS) binding protein and CD14-dependent activation of cytokine production. When lipoproteins were compared on the basis of protein content, R-HDL was most effective in reducing tumor necrosis factor alpha (TNF-alpha) production followed in order by very low density lipoprotein, low-density lipoprotein, Intralipid, and natural HDL. However, when these particles were compared by protein, phospholipid, cholesterol, or triglyceride content by stepwise linear regression analysis, only phospholipid was correlated to effectiveness (r2 = 0.873; P < 0.0001). Anti-CD14 monoclonal antibodies MY4 and 3C10 inhibited LPS binding protein and CD14-dependent activation of TNF-alpha production by LPS at LPS concentrations up to approximately 1.0 ng/ml. R-HDL (2 mg of protein per ml) blocked TNF-alpha production by LPS from both smooth- and rough-type gram-negative bacteria at concentrations up to 100 ng of LPS per ml but had little effect on heat-killed gram-positive Staphylococcus aureus and no effect on other LPS-independent stimuli tested. These results support our hypothesis that LPS is neutralized by binding to phospholipid on the surface of R-HDL and demonstrate that R-HDL is a potent inhibitor of the induction of TNF-alpha by LPS from both rough- and smooth-form gram-negative bacteria in whole human blood.
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PMID:Reconstituted high-density lipoprotein neutralizes gram-negative bacterial lipopolysaccharides in human whole blood. 752 33

The membrane-associated CD14 receptor (mCD14) is a monocyte/macrophage differentiation antigen, and it has been demonstrated to serve as a receptor for bacterial lipopolysaccharide (LPS; endotoxin). Binding of LPS to mCD14 has been shown to be associated with LPS-induced macrophage, monocyte, and neutrophil activation in humans. In this report, we describe the presence and function of an mCD14-like receptor on bovine alveolar macrophages (bAM). An immunofluorescence technique and flow cytometric analysis indicated binding of anti-human CD14 monoclonal antibodies (MAb) My4, 3C10, and 60bd to bAM. Binding of anti-CD14 MAb (3C10 and MY4) was reduced over 20% by pretreatment of bAM with phosphatidylinositol-specific phospholipase C (0.5 to 1.0 U/ml), indicating that bovine mCD14 is a glycosyl phosphatidylinositol-anchored protein. In addition, pretreatment of bAM with anti-CD14 MAb decreased binding of 125I-labeled LPS to macrophages, suggesting that bovine mCD14 serves as a receptor for LPS. A cDNA probe based on the human sequence for CD14 was used in Northern (RNA) blot analysis, and hybridization to human monocyte CD14 yielded the expected 1.5-kb band. Hybridization to bovine mRNA yielded a 1.5-kb band plus an unexpected 3.1-kb band. Constitutive expression of bovine CD14 mRNA was observed, and the expression level was modestly elevated in bAM stimulated for 24 h with LPS (1 ng/ml) in the presence of bovine serum. The function and activation of bAM were assessed by quantitation of tissue factor (TF) expression on the cells using an activated factor X-related chromogenic assay and S-2222 substrate. LPS (1 ng/ml)-mediated upregulation of TF expression on bAM was dependent on the presence of bovine serum components, and TF expression was inhibited by anti-CD14 MAb. In addition, TF mRNA levels in LPS-stimulated bAM were decreased by pretreatment of cells with anti-CD14 MAb (MAb 60bd, 10 micrograms/ml).
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PMID:CD14 and tissue factor expression by bacterial lipopolysaccharide-stimulated bovine alveolar macrophages in vitro. 752 35

CD14, a glycosylphosphatidylinositol-anchored protein on the surface of monocytes, macrophages, and polymorphonuclear leukocytes, is a receptor for lipopolysaccharide (LPS). CD14 binding of LPS is enhanced by serum proteins, especially lipopolysaccharide binding protein. The serum-dependent binding of LPS to CD14 stimulates macrophages to make cytokines, which can cause septic shock in humans and animals. Here, we identify a region in human CD14 which is important in serum-dependent LPS binding and LPS-induced cellular activation. Four small regions (4-5 amino acids long) within the N-terminal 65 amino acids of CD14 were deleted singly or in combination. The deletion mutants were stably expressed in Chinese hamster ovary (CHO) cells. The mutants were characterized in three assays: reactivity with anti-CD14 monoclonal antibody, serum-dependent LPS binding, and LPS-induced activation of NF-kappa B. Some of the mutants selectively lost reactivity with the anti-CD14 monoclonal antibody that inhibited serum-dependent LPS binding and cellular activation. All of the mutants bound much less LPS than wild type CD14 in the presence of serum. None of the mutants bound more LPS than control CD14-CHO cells in the absence of serum. CD14-CHO cells respond to LPS by activation of NF-kappa B. All of the deletion mutants were less active LPS receptors than wild type CD14-CHO cells. The delta AVEVE mutant, the delta DDED and delta PQPD double mutant, and the delta DDED, delta PQPD, delta AVEVE, and delta DPRQY quadruple deletion mutants were essentially inactive LPS receptors in CHO cells. These studies suggest that the 65 N-terminal amino acids of CD14 are critical for serum-dependent binding of LPS to CD14 and subsequent signal transduction in CHO cells.
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PMID:A region of human CD14 required for lipopolysaccharide binding. 752 31

Taxol, a microtubule stabilizer with anticancer activity, mimics the actions of lipopolysaccharide (LPS) on murine macrophages in vitro. Recently, it was shown that taxol-induced macrophage activation was inhibited by the LPS antagonist Rhodobacter sphaeroides diphosphoryl lipid A (RsDPLA). To investigate the mechanisms of taxol-induced macrophage activation, the present study focused on the interaction of LPS, RsDPLA, and taxol in the activation of and binding to macrophages. Taxol alone induced murine C3H/He macrophages to secrete tumor necrosis factor alpha (TNF) and to produce nitric oxide (NO) with kinetics similar to that of LPS. Macrophages from LPS-hyporesponsive C3H/HeJ mice, in contrast, did not yield any detectable TNF and NO production in response to LPS or taxol. RsDPLA inhibited taxol-induced TNF and NO production from C3H/He macrophages in a dose-dependent manner. The inhibition by RsDPLA was specific for LPS and taxol in that RsDPLA did not inhibit heat-killed Listeria monocytogenes- or zymosan-induced TNF production. Polymyxin B blocked the inhibitory effect of RsDPLA on taxol-induced TNF production. The inhibitory activity of RsDPLA appeared to be reversible since macrophages still responded to taxol in inducing TNF production after the RsDPLA was washed out with phosphate-buffered saline prior to the addition of taxol. Taxol-induced TNF production was not inhibited by colchicine, vinblastine, or 10-deacetylbaccatine III. A mutant cell line, J7.DEF3, defective in expression of a CD14 antigen, responded equally well to taxol by producing TNF as did the parent J774.1 cells. This suggested that the activation of macrophages by taxol does not require CD14. Taxol-induced TNF production by the mutant cells was also inhibited by RsDPLA. 125I-labeled LPS and 3H-labeled taxol was reported to bind to J774.1 cells predominantly via CD14 and microtubules, respectively. The binding of 125I-labeled LPS to J7.DEF3 cells was about 30 to 40% of that to J774.1 cells. The binding of 125I-LPS to J774.1 cells was inhibited by unlabeled LPS and RsDPLA but not by taxol. On the other hand, 3H-labeled taxol bound to both J774.1 cells and J7.DEF3 cells in similar time- and dose-dependent manners. The binding of [3H]taxol to these cells was inhibited by taxol but not by LPS or RsDPLA. Although the binding studies failed to examine cross competition for binding to macrophages, a possible explanation of these results is that LPS, RsDPLA, and taxol share the same molecule(s) on murine macrophages for their functional receptor(s), which is neither CD14 nor tubulin.
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PMID:CD14 is not involved in Rhodobacter sphaeroides diphosphoryl lipid A inhibition of tumor necrosis factor alpha and nitric oxide induction by taxol in murine macrophages. 752 46

We have examined basal and lipopolysaccharide (LPS)-induced release of interleukin 1 beta (IL-1 beta), interleukin 6 (IL-6), interleukin 8 (IL-8), tumour necrosis factor-alpha (TNF-alpha) and soluble CD14 (sCD14) in whole blood and peripheral blood mononuclear cells (PBMC) from 20 persons with either high (1.62-2.47 mmol/L) or low (0.43-1.29 mmol/L) levels of high-density lipoprotein (HDL). Whole blood was incubated at 37 degrees C for 2 h with 100 ng LPS/ml, while PBMC were incubated with 100 ng LPS/ml for up to 160 h. The LPS-induced release of IL-1 beta, IL-6, IL-8 and TNF-alpha into plasma showed no differences between the two HDL-groups; whereas levels of sCD14 were significantly higher in plasma in persons with low HDL (P < 0.01). PBMC incubated with LPS showed a significantly higher release of IL-1 beta (P = 0.01) and IL-6 (P = 0.02) in persons with high HDL at all sampling times. sCD14 was found not to be released by PBMC. These findings indicate that PBMC from persons with high or low levels of HDL have different functional properties, possibly of importance in inflammation and atherogenesis.
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PMID:LPS-induced release of IL-1 beta, IL-6, IL-8, TNF-alpha and sCD14 in whole blood and PBMC from persons with high or low levels of HDL-lipoprotein. 753 60


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