Abstract
There is evidence that low-density lipoprotein (LDL) is modified by hydrolytic enzymes, and that the product (E-LDL) induces selective production of interleukin 8 (IL-8) in endothelial cells. Since nuclear factor-kappaB (NF-kappaB) is a major regulator of IL-8 transcription, we studied its activation in endothelial cells treated with E-LDL. Unexpectedly, the modified lipoprotein not only failed to activate NF-kappaB, but completely blocked its activation by tumour necrosis factor-alpha (TNF-alpha) in EA.hy926-cells, as assessed by electrophoretic mobility shift assays and immunofluorescence. Inhibition occurred upstream of NF-kappaB translocation, as inhibitor of NF-kappaB- (IkappaB)-phosphorylation was suppressed by E-LDL. In contrast to NF-kappaB, transcription factor activator protein-1 (AP-1) proved to be activated. Removal of free fatty acids present in E-LDL obliterated both activation of AP-1 and inhibition of NF-kappaB. Chromatin immunoprecipitation revealed that phosphorylated c-jun, but not NF-kappaBp65 bound to the natural IL-8 promoter. Production of endothelial IL-8 and simultaneous modulation of NF-kappaB in response to hydrolyzed LDL might serve to protect the vessel wall and promote silent removal of the insudated lipoprotein.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Cell Line
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Endothelial Cells / drug effects
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Endothelial Cells / enzymology
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Endothelial Cells / metabolism*
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Fatty Acids, Nonesterified / metabolism
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Humans
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Hydrolysis
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I-kappa B Proteins / metabolism
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Imidazoles / pharmacology
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Inflammation / enzymology
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Inflammation / metabolism*
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Interleukin-8 / genetics
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Interleukin-8 / metabolism
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Lipoproteins, LDL / metabolism*
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NF-KappaB Inhibitor alpha
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Phosphorylation
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Promoter Regions, Genetic
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Protein Kinase Inhibitors / pharmacology
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Proto-Oncogene Proteins c-jun / metabolism
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Pyridines / pharmacology
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Sterol Esterase / metabolism
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Time Factors
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Transcription Factor AP-1 / metabolism
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Transcription Factor RelA / metabolism
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Trypsin / metabolism
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Tumor Necrosis Factor-alpha / metabolism
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p38 Mitogen-Activated Protein Kinases / antagonists & inhibitors
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p38 Mitogen-Activated Protein Kinases / metabolism
Substances
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CXCL8 protein, human
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Fatty Acids, Nonesterified
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I-kappa B Proteins
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Imidazoles
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Interleukin-8
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Lipoproteins, LDL
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NFKBIA protein, human
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Protein Kinase Inhibitors
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Proto-Oncogene Proteins c-jun
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Pyridines
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Transcription Factor AP-1
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Transcription Factor RelA
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Tumor Necrosis Factor-alpha
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NF-KappaB Inhibitor alpha
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p38 Mitogen-Activated Protein Kinases
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Sterol Esterase
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Trypsin
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SB 203580