Enzymatically hydrolyzed low-density lipoprotein modulates inflammatory responses in endothelial cells.
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.
Fenske
Dominic
D
Institute of Medical Microbiology and Hygiene, Johannes Gutenberg-University Mainz, Hochhaus am Augustusplatz, 55131 Mainz, Germany.
Dersch
Katrin
K
Lux
Cornelia
C
Zipse
Lisa
L
Suriyaphol
Prapat
P
Dragneva
Yolantha
Y
Han
Shan-Rui
SR
Bhakdi
Sucharit
S
Husmann
Matthias
M
D002460:Cell Line; D042783:Endothelial Cells / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D005230:Fatty Acids, Nonesterified / Q000378:metabolism; D006801:Humans; D006868:Hydrolysis; D020672:I-kappa B Proteins / Q000378:metabolism; D007093:Imidazoles / Q000494:pharmacology; D007249:Inflammation / Q000201:enzymology / Q000378:metabolism*; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism; D008077:Lipoproteins, LDL / Q000378:metabolism*; D000072000:NF-KappaB Inhibitor alpha; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology; D002787:Sterol Esterase / Q000378:metabolism; D013997:Time Factors; D018808:Transcription Factor AP-1 / Q000378:metabolism; D051996:Transcription Factor RelA / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
C508606:CXCL8 protein, human; D005230:Fatty Acids, Nonesterified; D020672:I-kappa B Proteins; D007093:Imidazoles; D016209:Interleukin-8; D008077:Lipoproteins, LDL; C000606204:NFKBIA protein, human; D047428:Protein Kinase Inhibitors; D016755:Proto-Oncogene Proteins c-jun; D011725:Pyridines; D018808:Transcription Factor AP-1; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D000072000:NF-KappaB Inhibitor alpha; D048051:p38 Mitogen-Activated Protein Kinases; D002787:Sterol Esterase; D014357:Trypsin; C093642:SB 203580