title: Multi-hit inhibition of circulating and cell-associated components of the toll-like receptor 4 pathway by oxidized phospholipids.
abstract: OBJECTIVE
  Oxidized phospholipids (OxPLs) that are abundant in atherosclerotic lesions are increasingly recognized as context-dependent lipid mediators demonstrating both pro- and antiinflammatory activities. Molecular mechanisms of their effects are largely unknown. Here we present novel information on the mechanisms whereby OxPLs modulate activation of TLR4 by lipopolysaccharide (LPS).
  
  
  RESULTS
  We show, using several cell types and various inflammatory genes as readouts, that different classes and molecular species of OxPLs do not stimulate TLR4 but exert prominent inhibitory effects on LPS-induced reactions. Our data demonstrate that binding of OxPLs to the LPS-binding protein (LBP) and CD14 prevents recognition of LPS by these proteins, thus impairing activation of TLR4. In addition, OxPLs inhibited LBP- and CD14-independent activation of TLR4 by the synthetic TLR4 agonist E6020 indicating that in parallel with LBP and CD14, OxPLs target cell-associated steps in TLR4 cascade.
  
  
  CONCLUSIONS
  Our data suggest that OxPLs inhibit action of LPS via a multi-hit mechanism. These results support the notion that OxPLs are endogenous inhibitors of TLR4 produced in response to oxidative stress.
authors.affiliation: Department of Vascular Biology and Thrombosis Research, Medical University of Vienna, Austria.
authors.forename: Elena
authors.initials: E
authors.lastname: von Schlieffen
authors.forename: Olga V
authors.initials: OV
authors.lastname: Oskolkova
authors.forename: Gernot
authors.initials: G
authors.lastname: Schabbauer
authors.forename: Florian
authors.initials: F
authors.lastname: Gruber
authors.forename: Stephan
authors.initials: S
authors.lastname: Blüml
authors.forename: Melinda
authors.initials: M
authors.lastname: Genest
authors.forename: Alexandra
authors.initials: A
authors.lastname: Kadl
authors.forename: Claudia
authors.initials: C
authors.lastname: Marsik
authors.forename: Sylvia
authors.initials: S
authors.lastname: Knapp
authors.forename: Jesse
authors.initials: J
authors.lastname: Chow
authors.forename: Norbert
authors.initials: N
authors.lastname: Leitinger
authors.forename: Bernd R
authors.initials: BR
authors.lastname: Binder
authors.forename: Valery N
authors.initials: VN
authors.lastname: Bochkov
mesh_terms: D000209:Acute-Phase Proteins / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D002478:Cells, Cultured; D019040:E-Selectin / Q000235:genetics / Q000378:metabolism; D042783:Endothelial Cells / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism; D007700:Kinetics; D018950:Lipopolysaccharide Receptors / Q000378:metabolism; D008070:Lipopolysaccharides / Q000378:metabolism / Q000494:pharmacology*; D008562:Membrane Glycoproteins / Q000378:metabolism; D010084:Oxidation-Reduction; D010743:Phospholipids / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism; D000099231:Lipopolysaccharide-Binding Protein
chemical_list: D000209:Acute-Phase Proteins; D002352:Carrier Proteins; D019040:E-Selectin; D018836:Inflammation Mediators; D015850:Interleukin-6; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D010743:Phospholipids; D012333:RNA, Messenger; D051197:Toll-Like Receptor 4; D014409:Tumor Necrosis Factor-alpha; D000099231:Lipopolysaccharide-Binding Protein; C508600:IL6 protein, human; C495345:TLR4 protein, human