title: Cardiac glycoside inhibits IL-8-induced biological responses by downregulating IL-8 receptors through altering membrane fluidity.
abstract: Considering the potential role of interleukin-8 (IL-8) in inflammation, angiogenesis, tumorogenesis, and metastasis, and the involvement of different cell types especially neutrophils and macrophages in those processes, the regulation of IL-8-mediated biological responses is important. In this report we provide evidences that oleandrin, a cardiac glycoside potentially inhibited IL-8-, formyl peptide (FMLP)-, EGF-, or nerve growth factor (NGF)-, but not IL-1- or TNF-induced NF-kappaB activation in macrophages. Oleandrin inhibited IL-8-, but not TNF-induced NF-kappaB-dependent genes expression. Oleandrin inhibited the binding of IL-8, EGF, or NGF, but not IL-1 or TNF. It decreased almost 79% IL-8 binding without altering affinity towards IL-8 receptors and this inhibition of IL-8 binding was observed in isolated membrane. The IL-8, anti-IL-8Rs antibodies, or protease inhibitors were unable to protect oleandrin-mediated inhibition of IL-8 binding. Phospholipids significantly protected oleandrin-mediated inhibition of IL-8 binding thereby restoring IL-8-induced NF-kappaB activation. Oleandrin altered the membrane fluidity as detected by microviscosity parameter and a decrease in diphenylhexatriene, a lipid binding fluorophore binding in a dose-dependent manner. Overall, our results suggest that oleandrin inhibits IL-8-mediated biological responses in diverse cell types by modulating IL-8Rs through altering membrane fluidity and microviscosity. The study might help to regulate IL-8-mediated biological responses involved in inflammation, metastasis, and neovascularization.
authors.affiliation: Laboratory of Immunology, Centre for DNA Fingerprinting & Diagnostics, Nacharam, Hyderabad, India. manna@cdfd.org.in
authors.forename: Sunil K
authors.initials: SK
authors.lastname: Manna
authors.forename: Yashin
authors.initials: Y
authors.lastname: Sreenivasan
authors.forename: Abira
authors.initials: A
authors.lastname: Sarkar
mesh_terms: D000469:Alkaline Phosphatase / Q000235:genetics / Q000378:metabolism; D000906:Antibodies / Q000276:immunology / Q000494:pharmacology; D002298:Cardenolides / Q000494:pharmacology*; D002301:Cardiac Glycosides / Q000494:pharmacology; D002460:Cell Line; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D002784:Cholesterol / Q000494:pharmacology; D051546:Cyclooxygenase 2 / Q000378:metabolism; D004161:Diphenylhexatriene / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects; D004815:Epidermal Growth Factor / Q000378:metabolism / Q000494:pharmacology; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D018922:HL-60 Cells; D006801:Humans; D051550:I-kappa B Kinase / Q000378:metabolism; D020672:I-kappa B Proteins / Q000378:metabolism; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D007375:Interleukin-1 / Q000378:metabolism / Q000494:pharmacology; D016209:Interleukin-8 / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D008560:Membrane Fluidity / Q000187:drug effects*; D008565:Membrane Proteins / Q000378:metabolism; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D052002:NF-kappa B p50 Subunit / Q000378:metabolism; D020932:Nerve Growth Factor / Q000378:metabolism / Q000494:pharmacology; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism; D010743:Phospholipids / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D011401:Promoter Regions, Genetic / Q000235:genetics; D011480:Protease Inhibitors / Q000494:pharmacology; D011956:Receptors, Cell Surface / Q000378:metabolism; D018123:Receptors, Interleukin / Q000276:immunology / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013110:Sphingosine / Q000494:pharmacology; D051996:Transcription Factor RelA / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism / Q000494:pharmacology; D020298:U937 Cells
chemical_list: D000906:Antibodies; D002298:Cardenolides; D002301:Cardiac Glycosides; D020672:I-kappa B Proteins; D007375:Interleukin-1; D016209:Interleukin-8; D008565:Membrane Proteins; D016328:NF-kappa B; D052002:NF-kappa B p50 Subunit; C000606204:NFKBIA protein, human; D010743:Phospholipids; D011480:Protease Inhibitors; D011956:Receptors, Cell Surface; D018123:Receptors, Interleukin; D011993:Recombinant Fusion Proteins; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D018799:Intercellular Adhesion Molecule-1; D000072000:NF-KappaB Inhibitor alpha; D049452:Green Fluorescent Proteins; D004161:Diphenylhexatriene; D009240:N-Formylmethionine Leucyl-Phenylalanine; D004815:Epidermal Growth Factor; D020932:Nerve Growth Factor; D002784:Cholesterol; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D051550:I-kappa B Kinase; D000469:Alkaline Phosphatase; C021065:oleandrin; D013110:Sphingosine