C-reactive protein activates the nuclear factor-kappaB signal transduction pathway in saphenous vein endothelial cells: implications for atherosclerosis and restenosis.
OBJECTIVE
Elevated levels of C-reactive protein are one of the strongest prognostic factors in atherosclerosis. In addition to predicting vascular disease, C-reactive protein may directly facilitate the development of a proinflammatory and proatherosclerotic phenotype. Recent studies have demonstrated marked up-regulation of various adhesion molecules and inflammatory responses in endothelial cells subjected to C-reactive protein. The nuclear factor-kappaB signal transduction is known to play a key role in the expression of these proatherogenic entities. This study examines the direct effects of C-reactive protein on nuclear factor-kappaB activation and related mechanisms in saphenous vein endothelial cells.


METHODS
The activation of nuclear factor-kappaB was determined by confocal microscopy assessing the nuclear localization of nuclear factor-kappaB in endothelial cells incubated with C-reactive protein (50 microg/mL) for 30 minutes and 3 hours. Cells not incubated with C-reactive protein were used as negative controls, and cells incubated with tumor necrosis factor-alpha (10 ng/mL) for 15 minutes were used as positive controls in all studies. The degradation of IkappaB-alpha and IkappaB-beta was assessed by Western blotting of the cell lysates obtained from cells incubated with human recombinant C-reactive protein (50 microg/mL) for 15 minutes, 30 minutes, and 1 hour.


RESULTS
Nuclear factor-kappaB nuclear translocation in endothelial cells increased significantly after 30 minutes of incubation with C-reactive protein (P <.01). Nuclear localization of nuclear factor-kappaB returned to baseline levels after 3 hours of incubation with C-reactive protein. Incubation with C-reactive protein resulted in degradation of IkappaB-alpha that was maximal at 30 minutes (P <.05). C-reactive protein showed no significant effect on IkappaB-beta degradation.


CONCLUSIONS
These data demonstrate, for the first time, that C-reactive protein activates the nuclear factor-kappaB signal transduction pathway in endothelial cells. Degradation of IkappaB-alpha, but not IkappaB-beta, seems to be the major pathway leading to nuclear factor-kappaB nuclear translocation and activation induced by C-reactive protein. These data support the concept that C-reactive protein, at concentrations known to predict diverse vascular insults, directly facilitates a proinflammatory and proatherosclerotic phenotype through activation of nuclear factor-kappaB. These data have important implications for saphenous vein atherosclerosis in patients with elevated C-reactive protein levels.
Verma
Subodh
S
Division of Cardiac Surgery, Toronto General Hospital, University of Toronto, Ontario, Canada. subodh.verma@sympatico.ca
Badiwala
Mitesh V
MV
Weisel
Richard D
RD
Li
Shu-Hong
SH
Wang
Chao-Hung
CH
Fedak
Paul W M
PW
Li
Ren-Ke
RK
Mickle
Donald A G
DA
D001161:Arteriosclerosis / Q000378:metabolism* / Q000503:physiopathology; D015153:Blotting, Western; D002097:C-Reactive Protein / Q000494:pharmacology* / Q000502:physiology; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000378:metabolism*; D006651:Histocytochemistry; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism; D018613:Microscopy, Confocal; D016328:NF-kappa B / Q000378:metabolism*; D011994:Recombinant Proteins / Q000494:pharmacology; D012501:Saphenous Vein / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects
D020672:I-kappa B Proteins; D016328:NF-kappa B; D011994:Recombinant Proteins; D002097:C-Reactive Protein