Abstract 1362: Overexpression of Redox Factor-1 Inhibits Tumor Necrosis Factor-Alpha-Induced Vascular Cell Adhesion Molecule-1 and Monocyte Adhesion in the Vascular Endothelial Cells
Background : Redox factor-1 (Ref-1) is a ubiquitous protein that is a redox-sensitive regulator of multiple transcription factors as well as an apurinic/apyrimidic endonuclase in the base excision repair pathway. Monocyte adhesion to vascular endothelial cells seems to be initial and crucial events in the pathological process of the inflammatory diseases, such as atheriosclerosis. Recently, it has been uncovered extra-nuclear role of Ref-1 against the oxidative stress in the vascular cells. Therefore we asssessed the hypothesis that Ref-1 has an inhibitory action on the vascular inflammation in the vascular endothelial cells.
Methods and Results : Endothelial activation as a model of vascular inflammation in the cultured human umbilical vein endothelial cells was induced by the treatment of tumor-necrosis factor-alpha (TNF-α). Overexpression of Ref-1 in the endothelial cells was performed by the transfection with an adenovirus encoding human Ref-1 cDNA. Adenoviral overexpression Ref-1 significantly inhibited TNF-α-induced induction of vascular cell adhesion molecule-1 and monocyte adhesion on the endothelial cells. Ref-1-mediated suppression on the TNF-α-induced vascular cell adhesion molecule-1 was blocked by pretreatment of nitric oxide synthase inhibitor, L-nitroarginine methyl ester. Furthermore, overexpression of Ref-1 inhibited TNF-α-induced increase in the intracellular superoxide production by using the superoxide-sensitive fluorophore dihydroethidine. However, overexpression of Ref-1 did not affect the expression of copper/zinc superoxide dismutase in the endothelial cells.
Conclusions: These data provide evidence that Ref-1 in the endothelial cells suppressed TNF-α-induced vascular cell adhesion molecule-1 and monocyte adhesion through a nitric oxide-dependent mechanism, and by inhibiting the intracellular oxidative stress in the endothelial cells. Considering the biological functions of Ref-1, endogenous vascular Ref-1 might serve an anti-inflammatory action.