title: Sphingosine-1-phosphate increases human alveolar epithelial IL-8 secretion, proliferation and neutrophil chemotaxis.
abstract: Sphingosine-1-phosphate (S1P) has been presented recently as a pro-inflammatory agent in the airway epithelium since S1P levels are increased in bronchoalveolar lavage fluid of human asthmatics. However, the effects of S1P over the alveolar epithelium and neutrophil interactions are poorly understood. Here, we show that S1P increased interleukin 8 (IL-8) gene expression and protein secretion and proliferation in alveolar epithelial cells A549 at physiological concentrations (1 microM). At the same time, S1P increased intracellular Ca2+ concentration (potency 17.91 microM, measured by epifluorescence microscopy), phospholipase D (PLD) activity (measured by chemiluminiscence method) and extracellular matrix-regulated kinase1/2 (ERK1/2) phosphorylation (measured by western blot) via G(i)-coupled receptor (inhibited by pertussis toxin 100 ng/ml) in A549 cells. Both, IL-8 secretion and A549 proliferation were dependent of PLD activity (inhibited by 1-butanol 0.5%), intracellular Ca2+ (inhibited by acetoxymethyl 1,2-bis(2-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid (BAPTA-AM) 100 microM), ERK1/2 phosphorylation (inhibited by 2-[2-amino-3-methoxyphenyl]-4H-1-benzopyran-4-one (PD98059) 10 microM) and G(i)-coupled receptors (blocked by pertussis toxin 100 ng/ml). Moreover, S1P increased intercellular adhesion molecule I (ICAM-1) expression and failed in vascular cell adhesion molecule I (VCAM-1) modification (measured by flow cytometer) in A549. Indirectly, A549 supernatant fluids arising from A549-S1P 1 microM stimulation decreased L-selectin expression without CD11b/CD18 integrin modification in human neutrophils. In the same way, A549-S1P supernatant fluids increased neutrophil chemotaxis (Boyden chamber), which was inhibited by antibody against IL-8. This study demonstrates for the first time that S1P participates in the alveolar epithelial interactions in vitro.
authors.affiliation: Department of Pharmacology, Faculty of Medicine, University of Valencia, Spain. xmilara@hotmail.com
authors.forename: Javier
authors.initials: J
authors.lastname: Milara
authors.forename: Manuel
authors.initials: M
authors.lastname: Mata
authors.forename: Maria Dolores
authors.initials: MD
authors.lastname: Mauricio
authors.forename: Eva
authors.initials: E
authors.lastname: Donet
authors.forename: Esteban J
authors.initials: EJ
authors.lastname: Morcillo
authors.forename: Julio
authors.initials: J
authors.lastname: Cortijo
mesh_terms: D020001:1-Butanol / Q000494:pharmacology; D002118:Calcium / Q000037:antagonists & inhibitors / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D002634:Chemotaxis, Leukocyte / Q000187:drug effects*; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005419:Flavonoids / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D016209:Interleukin-8 / Q000378:metabolism*; D049449:Luminescence; D008246:Lysophospholipids / Q000494:pharmacology*; D009504:Neutrophils / Q000187:drug effects; D037342:Pertussis Toxin / Q000494:pharmacology; D010739:Phospholipase D / Q000037:antagonists & inhibitors / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011650:Pulmonary Alveoli / Q000166:cytology; D043562:Receptors, G-Protein-Coupled / Q000037:antagonists & inhibitors; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D005419:Flavonoids; D016209:Interleukin-8; D008246:Lysophospholipids; D043562:Receptors, G-Protein-Coupled; D018799:Intercellular Adhesion Molecule-1; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; C060506:sphingosine 1-phosphate; D004533:Egtazic Acid; D020001:1-Butanol; D037342:Pertussis Toxin; D048049:Extracellular Signal-Regulated MAP Kinases; D010739:Phospholipase D; D013110:Sphingosine; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D002118:Calcium