C-reactive protein activates the nuclear factor-kappaB signal transduction pathway in saphenous vein endothelial cells: implications for atherosclerosis and restenosis.

OBJECTIVES

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.