Monocyte Arrest and Transmigration on Inflamed Endothelium in Shear Flow Is Inhibited by Adenovirus-Mediated Gene Transfer of IκB-α

Abstract

AbstractMobilization of nuclear factor-κB (NF-κB) activates transcription of genes encoding endothelial adhesion molecules and chemokines that contribute to monocyte infiltration critical in atherogenesis. Inhibition of NF-κB has been achieved by pharmacological and genetic approaches; however, monocyte interactions with activated endothelium in shear flow following gene transfer of the NF-κB inhibitor IκB-α have not been studied. We found that overexpression of IκB-α in endothelial cells using a recombinant adenovirus prevented tumor necrosis factor-α (TNF-α)–induced degradation of IκB-α and suppressed the upregulation of vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), and E-selectin mRNA and surface protein expression and the upregulation of transcripts for the chemokines monocyte chemoattractant protein 1 (MCP-1) and growth-related activity-α (GRO-α) by TNF-α. This was associated with a reduction in endothelial MCP-1 secretion and GRO-α immobilization. Adhesion assays under physiological shear flow conditions showed that firm arrest, spreading, and transmigration of monocytes on TNF-α–activated endothelium was markedly inhibited by IκB-α overexpression. Inhibition with monoclonal antibodies and peptide antagonists inferred that this was due to reduced expression of Ig integrin ligand as well as of chemokines specifically involved in these events. In contrast, rolling of monocytes was increased by IκB-α transfer and was partly mediated by P-selectin; however, it appeared to be unaffected by the inhibition of E-selectin induction. Thus, our data provide novel evidence that selective modulation of NF-κB by adenoviral transfer of IκB-α impairs the expression of multiple endothelial gene products required for subsequent monocyte arrest and emigration in shear flow and thus for monocyte infiltration in atherosclerotic plaques.