title: Lipopolysaccharide and sphingosine-1-phosphate cooperate to induce inflammatory molecules and leukocyte adhesion in endothelial cells.
abstract: Given that TLRs and sphingosine-1-phosphate (S1P) are key players in inflammation, we explored the potential interplay between TLRs and S1P in the adhesion/inflammatory pathways in primary human endothelial cells. As determined by Western blot and flow cytometry, cells treated with LPS (a TLR4 ligand) and S1P showed significantly enhanced expression of adhesion molecules such as ICAM-1 and E-selectin compared with the effect of either ligand alone. Cell-type differences on E-selectin upregulation were observed. In contrast, no cooperation effect on ICAM-1 or E-selectin was observed with a TLR2/TLR1 ligand. Consistent with an increase in adhesion molecule expression, endothelial cell treatment with LPS plus S1P significantly enhanced adhesion of PBMCs under shear stress conditions compared with the effect of either ligand alone and exhibited comparable levels of cell adhesion strength as those after TNF-α treatment. Moreover, LPS and S1P cooperated to increase the expression of proinflammatory molecules such as IL-6, cyclooxygenase-2, and prostacyclin, as determined by ELISA and Western blot. The analysis of signaling pathways revealed the synergistic phosphorylation of ERK upon LPS plus S1P treatment of HUVEC and human aortic endothelial cells and cell-type differences on p38 and NF-κB activation. Moreover, pharmacological and small interfering RNA experiments disclosed the involvement of S1P(1/3) and NF-κB in the cooperation effect and that cell origin determines the S1P receptors and signaling routes involved. Sphingosine kinase activity induction upon LPS plus S1P treatment suggests S1P- Sphingosine kinase axis involvement. In summary, LPS and S1P cooperate to increase proinflammatory molecules in endothelial cells and, in turn, to augment leukocyte adhesion, thus exacerbating S1P-mediated proadhesive/proinflammatory properties.
authors.affiliation: Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas and Universidad de Valladolid, Valladolid 47003, Spain.
authors.forename: Isabel
authors.initials: I
authors.lastname: Fernández-Pisonero
authors.forename: Ana I
authors.initials: AI
authors.lastname: Dueñas
authors.forename: Olga
authors.initials: O
authors.lastname: Barreiro
authors.forename: Olimpio
authors.initials: O
authors.lastname: Montero
authors.forename: Francisco
authors.initials: F
authors.lastname: Sánchez-Madrid
authors.forename: Carmen
authors.initials: C
authors.lastname: García-Rodríguez
mesh_terms: D002448:Cell Adhesion / Q000187:drug effects; D002478:Cells, Cultured; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000276:immunology; D004357:Drug Synergism; D019040:E-Selectin / Q000235:genetics / Q000276:immunology; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000276:immunology / Q000473:pathology; D011464:Epoprostenol / Q000235:genetics / Q000276:immunology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000235:genetics / Q000276:immunology; D005786:Gene Expression Regulation / Q000187:drug effects; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects* / Q000276:immunology / Q000473:pathology; D006801:Humans; D007249:Inflammation / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics / Q000276:immunology; D015850:Interleukin-6 / Q000235:genetics / Q000276:immunology; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000276:immunology / Q000473:pathology; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008246:Lysophospholipids / Q000494:pharmacology*; D016328:NF-kappa B / Q000235:genetics / Q000276:immunology; D009928:Organ Specificity; D015398:Signal Transduction / Q000187:drug effects; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D051193:Toll-Like Receptors / Q000235:genetics / Q000276:immunology; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000276:immunology
chemical_list: D019040:E-Selectin; C508600:IL6 protein, human; D015850:Interleukin-6; D008070:Lipopolysaccharides; D008246:Lysophospholipids; D016328:NF-kappa B; D051193:Toll-Like Receptors; D018799:Intercellular Adhesion Molecule-1; C060506:sphingosine 1-phosphate; D011464:Epoprostenol; D051546:Cyclooxygenase 2; D048049:Extracellular Signal-Regulated MAP Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D013110:Sphingosine