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

We examined the mechanisms involved in neutrophil adherence to cultured human umbilical vein endothelial cells (HEC) induced by direct stimulation of the neutrophils by phorbol myristate acetate (PMA), formylmethionyl-leucyl-phenylalanine (FMLP), or the calcium ionophore A23187 (neutrophil-dependent adherence), or by pretreatment of HEC with interleukin-1 (IL-1), tumour necrosis factor (TNF) or lipopolysaccharide (LPS) (endothelial-dependent adherence). Two distinct mechanisms for neutrophil adherence to HEC were demonstrated by performing adherence assays: (i) at 37 degrees versus 4 degrees; (ii) in the presence of Ca2+ only versus Mg2+ only; and (iii) in the presence or absence of monoclonal antibodies (mAb) to the CD11/CD18 adhesion complex of neutrophils. A CD11/CD18-dependent mechanism (i.e. inhibited by anti-CD18 mAb) was identified that was active in the presence of Mg2+ only but not of Ca2+ only, and at 37 degrees but not at 4 degrees. A CD11/CD18-independent mechanism (i.e. not inhibited by anti-CD18 mAb) was active at 4 degrees and at 37 degrees, and in the presence of Ca2+ only and of Mg2+ only. Neutrophil-dependent adherence induced by FMLP or PMA occurred solely via the CD11/CD18-dependent mechanism, whereas endothelial-dependent adherence induced by a 4-hr pretreatment with IL-1, TNF, or LPS involved both CD11/CD18-dependent and/independent mechanisms. CD11/CD18-deficient neutrophils isolated from a patient with leucocyte adherence deficiency (LAD) maintained the ability to adhere to LPS-pretreated HEC in the presence of Ca2+ only, indicating that this mechanism of adherence involves a receptor on the neutrophil distinct from CD11/CD18. Furthermore, the disappearance of the CD11/CD18-independent, but not of the CD11/CD18-dependent mechanism of adherence, in HEC treated with TNF for 24 hr suggests that the two mechanisms of neutrophil adherence also involve distinct inducible endothelial-leucocyte adhesion molecules (E-LAM).
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PMID:CD11/CD18-independent neutrophil adherence to inducible endothelial-leucocyte adhesion molecules (E-LAM) in vitro. 257 36

Adherence of circulating neutrophils to the microvascular endothelium is the initial step in diapedesis, the process by which leukocytes migrate through blood vessels to accumulate at sites of cutaneous disease or injury. The mechanisms underlying neutrophil-endothelial cell interactions are currently under intense investigation. It has now been clearly shown that human neutrophil adherence in vitro to cultured human endothelial cell monolayers can be enhanced by a variety of mediators of inflammation, that both the neutrophil and the endothelial cell may actively contribute to the adhesive interaction depending on the stimuli involved, and that the Mac-1, LFA-1, p150,95 glycoprotein family (CD11/CD18) plays a critical role. Chemotactic peptides (FMLP, C5a) and lipid mediators (LTB4, PAF) act primarily on the neutrophil to enhance its adherence to endothelium. The effect occurs quickly (maximal response within 2 min), can be rapidly modulated, and is dependent on the expression of CD11/CD18 on the neutrophil surface. In contrast, the cytokines, interleukin-1 (IL-1) and tumor necrosis factor (TNF), as well as bacterial lipopolysaccharide (LPS), induce cultured human endothelial cells to increase their adhesivity for human neutrophils by a process that is time-dependent, requiring 4 to 6 h for maximal response, and involves de novo RNA and protein synthesis. Two adhesion molecules are induced on the surface of endothelium in response to cytokine activation: endothelial-leukocyte adhesion molecule-1 (ELAM-1) and intercellular adhesion molecule-1 (ICAM-1). ICAM-1 is a ligand for LFA-1 (CD11a/CD18). Thus, CD11/CD18 plays a central role in neutrophil adherence to endothelium stimulated by chemotactic factors or cytokines. However, much still remains to be explored to further understanding of the fascinating but complex interaction of circulating neutrophils and the microvascular endothelium during acute inflammatory reactions in the skin.
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PMID:Neutrophil-endothelial cell interactions: mechanisms of neutrophil adherence to vascular endothelium. 266 23

Human neutrophil (PMN) attachment to human umbilical vein endothelial cells (HUVEC) was evaluated in vitro using two MAbs, R6-5-D6 and RR1/1, that recognize intercellular adhesion molecule-1 (ICAM-1), and one MAb, TS1/18, that recognizes CD18. Pretreatment of the HUVEC with anti-ICAM-1 MAbs produced greater than 50% inhibition of attachment to HUVEC, and IL-1 (0.5 U/ml)- or lipopolysaccharide (LPS) (10 ng/ml)-stimulated HUVEC, and greater than 99% inhibition of f-Met-Leu-Phe (0.5 nM) enhanced adherence. Anti-ICAM-1 MAbs also inhibited by greater than 85% the transendothelial migration induced by 4-h IL-1 (0.5 U/ml) and LPS (10 ng/ml) activation of the HUVEC. That these effects involved a CD18-dependent mechanism is supported by the following results: pretreatment of PMN with TS1/18 produced the same degree of inhibition of attachment and migration as seen with R6-5-D6. In addition, the use of both MAbs together did not further increase the inhibition of cell attachment to stimulated HUVEC. The attachment of PMN from patients with CD18 deficiency to stimulated HUVEC was not reduced by R6-5-D6, and both R6-5-D6 and TS1/18 revealed the same time course for appearance and disappearance of an adherence component on stimulated HUVEC not blocked by either MAb. These results demonstrate that attachment and transendothelial migration of PMN in vitro depend substantially on both CD18 on the PMN and ICAM-1 on the endothelial cell.
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PMID:Recognition of an endothelial determinant for CD 18-dependent human neutrophil adherence and transendothelial migration. 290 80

Intratracheal injection of endotoxin [lipopolysaccharide (LPS)] in rats causes acute inflammation characterized by the emigration of neutrophils (PMNs) into the bronchoalveolar airspace. Antibody to PMN adhesion molecule CD11a inhibited LPS-initiated PMN accumulation in bronchoalveolar lavage (BAL) fluid by 32% (P < 0.001). Antibody to the endothelial CD11a counterreceptor intercellular adhesion molecule-1 (ICAM-1) inhibited LPS-initiated PMN accumulation in BAL fluid by 66% (P < 0.0001). Combined antibody blockade of ICAM-1 and the C-X-C chemokine cytokine-induced neutrophil chemoattractant (CINC) inhibited LPS-initiated PMN emigration by 80%, significantly more than antibody against either ICAM-1 or CINC alone. To study the relative contribution of alveolar macrophages and PMNs to intra-alveolar tumor necrosis factor (TNF), the LPS-induced TNF in BAL fluid was measured after depletion of circulating PMNs with a cytolytic antibody to CD18. Although the anti-CD18 antibody completely abrogated LPS-initiated PMN emigration into BAL fluid, TNF levels in BAL fluid were unaffected, suggesting that alveolar macrophages are the predominant cellular source of LPS-induced TNF production. In conclusion, 1) CD11a, ICAM-1, and CINC play major roles in the LPS-initiated emigration of PMNs into the bronchoalveolar space, and 2) the TNF that drives ICAM-1 and CINC expression is derived largely from alveolar macrophages rather than PMNs.
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PMID:Intratracheal injection of endotoxin and cytokines. IX. Contribution of CD11a/ICAM-1 to neutrophil emigration. 749 85

The nature of the binding sites for lipopolysaccharide (LPS) on human monocytes was investigated using fluorescein isothiocyanate (FITC)-labelled LPS from Salmonella minnesota R595 (ReLPS). In the absence of serum, ReLPS bound to monocytes and this interaction was trypsin sensitive. A concentration of 0.1 mg/ml resulted in a 90% loss of LPS binding, while low concentrations increased this binding. Trypsin-treated monocytes recovered FITC-ReLPS binding after 20 hr culture, which was abrogated in the presence of cycloheximide and actinomycin D. This showed that de novo protein and mRNA synthesis were essential. A number of different proteins have been implicated in cellular binding of LPS to monocytes. In this paper we show that CD14 is not involved in direct binding of FITC-ReLPS to monocytes, since anti-CD14 monoclonal antibody (mAb) (3C10) and removal of most of cell-surface CD14 by phosphatidylinositol-specific phospholipase C did not prevent FITC-ReLPS binding. Furthermore, LPS also bound to CD14-deficient cells from a patient with paroxysmal nocturnal haemoglobinuria (PNH). FITC-ReLPS binding was not mediated by the CD11/CD18 complex since mAb to the alpha and beta chains of the CD11/CD18 complex did not alter the binding of FITC-ReLPS to cells. These observations indicate that ReLPS may interact with monocyte membrane protein(s) in the absence of serum. This binding site(s) for LPS might be different from those previously described by others.
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PMID:Serum-independent binding of lipopolysaccharide to human monocytes is trypsin sensitive and does not involve CD14. 750 49

Human neutrophils are primed in the presence of complexes of lipopolysaccharide (LPS) with its serum binding protein (LBP) in a manner dependent on CD14. Cellular consequences of priming include increased responsiveness, the upregulation of surface proteins including the adhesive integrin CD11b/CD18 (Mac-1), the increased binding of certain ligands to CD11b/CD18, and the concurrent shedding of the L-selectin homing receptor. Because expression of both CD11b/CD18 and L-selectin is obligatory for formyl peptide-stimulated neutrophil aggregation in vitro (Simon et al, Blood 82:1097, 1993), we have examined the consequences of bacterial endotoxin on the expression of neutrophil adhesive molecules. We observed that the exposure of neutrophils to LPS/LBP, while enhancing the surface numbers and adhesive function of CD11b/CD18 for latex particles, did not induce aggregation. In contrast, as the LPS/LBP concentration increased (ED50 = 30 ng/mL LPS/LBP), the ability of neutrophils to aggregate decreased in parallel with the shedding of L-selectin. Moreover, when L-selectin adhesive activity was blocked by treatment with Fab fragments of Dreg-200, aggregation was inhibited to an extent roughly proportional to the available L-selection. Blocking of LPS/LBP with CD14-specific monoclonal antibodies suppressed L-selectin shedding and preserved formyl peptide-stimulated aggregation. Taken together, the data suggest that inhibition of neutrophil aggregation by LPS/LBP is related to the expression of L-selectin via CD14 rather than LPS inhibition of CD11b/CD18 function during cellular stimulation.
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PMID:Lipopolysaccharide enhances CD11b/CD18 function but inhibits neutrophil aggregation. 751 6

Previous studies have demonstrated that alveolar macrophages (AMphis) adherent to plastic release interleukin-8 in response to lipopolysaccharide (LPS). We sought to determine whether LPS could also alter surface adhesion molecule expression and thus modulate additional AMphi adhesive interactions. Canine AMphis obtained by bronchoalveolar lavage of excised lung were adhered onto tissue culture plastic and exposed to LPS (0.01 to 100 ng/ml). Expression of beta 2 integrins and intercellular adhesion molecule-1 (ICAM-1) was subsequently determined by flow cytometry, a cDNA probe to canine ICAM-1 was used to quantify ICAM-1 mRNA, and changes in adhesion molecule function were assessed by evaluating the extent of homotypic aggregation. ICAM-1 and CD11a/CD18 were present on freshly isolated AMphis. CD11b/CD18 and CD11c/CD18 were expressed at lower levels. Nonadherent AMphis expressed a pattern of beta 2 integrin and ICAM-1 comparable to adherent cells. During short-term LPS stimulation (3 h), adherent AMphis increased both the synthesis and expression of ICAM-1. CD18 expression was either decreased or remained unchanged with LPS stimulation. LPS stimulation in vitro (> 0.01 ng/ml) enhanced the homotypic aggregation of adherent AMphis. Aggregation was blocked by monoclonal antibodies to ICAM-1 (CL18/6) and CD11a (R7.1) and CD18 (R15.7). Similar kinetics were found for expression of ICAM-1 and homotypic aggregation, suggesting that up-regulation of ICAM-1 is a major determinant of the LPS-stimulated aggregation of AMphis.
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PMID:Induction of intercellular adhesion molecule-1 by lipopolysaccharide in canine alveolar macrophages. 752 15

CD11c/CD18 is a member of the leukocyte integrin family, heterodimeric adhesion molecules that interact with a diverse repertoire of ligands, including bacterial lipopolysaccharide (LPS). Their role as signal transducing receptors remains uncertain. We used a heterologous expression system to determine if CD11c/CD18 was capable of initiating signal transduction in response to LPS-binding, as assessed by the induced translocation of nuclear factor-kappa B. We have previously reported that Chinese hamster ovary (CHO)-K1 fibroblasts, normally unresponsive to LPS, acquire serum-dependent macrophage-like responses to LPS when transfected with CD14 (Golenbock, D.T., Y. Liu, F. Millham, M. Freeman, and R. Zoeller. 1993. J. Biol. Chem. 268:22055-22059), a known LPS receptor. In contrast, CHO cells acquired serum-independent responses to Gram-negative bacteria and LPS when transfected with CD11c/CD18 (CHO/CD11c). In comparison to CHO cells transfected with CD14 (CHO/CD14), responses in CHO/CD11c cells were slower, required higher endotoxin concentrations for maximal response, and were not inhibited by the presence of antibodies to CD14. CD11c/CD18 is, thus, the second phagocyte receptor, in addition to CD14, which has been shown to have the capacity to activate cells after binding to LPS. The function of this receptor in normal phagocytes may be limited to the recognition of LPS in infected tissues, where LPS-CD14 interactions are not favored because of the absence of serum proteins.
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PMID:CD11c/CD18, a transmembrane signaling receptor for lipopolysaccharide. 753 39

We have examined the effect of the virulent Leptospira interrogans strain Teramo, serotype icterohemorrhagiae, on the adherence of human neutrophilic polymorphonuclear leukocytes (PMN) to cultured human umbilical vein endothelial cells (HEC). Selective pretreatment of HEC with intact or sonicated leptospires caused a dose- and time-dependent increase of HEC-PMN adhesion (13.2% +/- 2.5% adherence to untreated HEC versus 46.3% +/- 5.6% adherence to HEC pretreated for 4 h with 10(8) intact leptospires per ml [mean +/- standard error of six experiments; P < 0.001]). In contrast, selective leptospire pretreatment of PMN or the addition of leptospires during the adherence assay did not alter HEC-PMN adherence. Leptospire induction of endothelial-cell adhesiveness occurred without detectable HEC damage and was prevented by RNA and protein synthesis inhibitors and by monoclonal antibodies to the CD11/CD18 adhesion complex of neutrophils and to the endothelial-leukocyte adhesion molecule 1 (ELAM-1) of endothelial cells. Similar results were obtained with pretreatment of HEC with interleukin-1 or with the lipopolysaccharide (LPS) of the gram-negative bacterium Escherichia coli. The possibility that contamination by the LPS of gram-negative bacteria could be involved in the induction of HEC adhesiveness was ruled out by the observation that the LPS inhibitor polymyxin B, which abolished the proadhesive effect of E. coli LPS, was ineffective in inhibiting leptospire- as well as interleukin-1-induced adherence. Similarly, leptospire LPSs seemed to have no role in the increase of endothelial-cell adhesiveness, since pretreatment of HEC with a leptospire LPS extract (phenol-water method) or with a leptospire total lipid extract failed to induce the proadhesive phenotype for neutrophils. Instead, peptidoglycans extracted from our leptospires actively stimulated the endothelial proadhesive activity for neutrophils (16.5% +/- 2.1% adherence to untreated HEC versus 51.2% +/- 2.9% adherence to HEC pretreated for 4 h with 1 microgram of peptidoglycan per ml; [mean +/- standard error of four experiments; P < 0.001]). This peptidoglycan-induced activity was inhibited by monoclonal antibodies to the CD11/CD18 adhesion complex and to ELAM-1 but not by polymyxin B. We conclude that peptidoglycans from pathogenic leptospires are among the molecules that can directly activate vascular endothelial cells to increase their adhesiveness for neutrophilic granulocytes. These observations may contribute to a better understanding of the mechanisms whereby non-gram-negative bacteria modulate the local and systemic inflammatory reaction.
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PMID:Leptospira icterohemorrhagiae and leptospire peptidolgycans induce endothelial cell adhesiveness for polymorphonuclear leukocytes. 754 37

Acute lethality was induced in rabbits by the sequential injection of Propionibacterium acnes and lipopolysaccharide (LPS). P. acnes induced the infiltration of inflammatory cells into the liver lobules during the early phase, and LPS in the late phase caused death in association with pathological changes mimicking hepatocellular necrosis or degeneration around infiltrated mononuclear cells and fibrin deposition in the liver, lung, and kidney, suggestive of a systemic Schwartzman-like reaction. These pathological changes were accompanied by the elevation of plasma tumor necrosis factor (TNF) and interleukin-8 (IL-8) levels. A neutralizing antibody to a leukocyte adhesion molecule, integrin beta 2 (CD18), administered at the time of LPS challenge, prevented reduced the elevation of plasma TNF and IL-8 levels. An anti-TNF alpha antibody but not an anti-IL-8 mediator in this model. These results indicate that CD18 is critically involved in vivo in activating leukocytes to produce cytokines in response to LPS.
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PMID:Prevention of endotoxin-induced acute lethality in Propionibacterium acnes-primed rabbits by an antibody to leukocyte integrin beta 2 with concomitant reduction of cytokine production. 759 Nov 40


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