Open AccessOxidized low density lipoproteins downregulate LPS‐induced platelet‐activating factor receptor expression in human monocyte‐derived macrophages
Author(s) -
Hourton Delphine,
Stengel Dominique,
Chapman M. John,
Ninio Ewa
Publication year - 2001
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.2001.02372.x
Subject(s) - lipopolysaccharide , lysophosphatidylcholine , downregulation and upregulation , chemistry , platelet activating factor , monocyte , macrophage , electrophoretic mobility shift assay , microbiology and biotechnology , receptor , western blot , platelet activating factor receptor , u937 cell , endocrinology , medicine , gene expression , biochemistry , biology , in vitro , antagonist , gene , phospholipid , phosphatidylcholine , membrane
Monocytes/macrophages play a key role in atherogenesis due to their inflammatory properties including formation of lipid mediators such as platelet‐activating‐factor (PAF). We investigated the effect of oxidized low‐density lipoprotein (oxLDL) on lipopolysaccharide (LPS)‐induced PAF receptor (PAF‐R) expression in human macrophages and the implication of the nuclear factor (NF)‐κB in this regulation. LPS‐treatment (1 µg·mL −1 ) of macrophages increased PAF binding and PAF‐R mRNA expression by 56% ( P < 0.05) and twofold ( P < 0.01), respectively. In contrast, highly oxidized low‐density lipoprotein [ox 24h LDL; 100 µg·mL −1 ; thiobarbituric acid reacting substances: 31 ± 3 nmol equiv. malondialdehyde (MDA)·mg protein LDL −1 ] diminished PAF‐R expression (−69%; P < 0.05) and mRNA level (− 45%; P < 0.01). LPS pretreatment induced the activated form of p65 in the nuclear compartment of macrophages (detected by Western blotting) and NF‐κB binding activity (by electrophoretic mobility shift assay). Treatment of macrophages with ox 24h LDL suppressed the LPS‐induced binding of NF‐κB to DNA. In addition, treatment of macrophages with lysophosphatidylcholine (2 and 10 µ m ), a major component of oxLDL, inhibited the LPS‐induced NF‐κB binding to DNA and reduced PAF binding by 30 and 70%, respectively. In conclusion, oxLDL may downregulate PAF‐R expression in human macrophages by inhibiting LPS‐induced NF‐κB binding to DNA.