INHIBITION OF ENDOTHELIAL-CELL ACTIVATION BY ADENOVIRUS-MEDIATED EXPRESSION OF I-KAPPA-B-ALPHA, AN INHIBITOR OF THE TRANSCRIPTION FACTOR NF-KAPPA-B

During the inflammatory response, endothelial cells (EC) transiently u pregulate a set of genes encoding, among others, cell adhesion molecul es and chemotactic cytokines that together mediate the interaction of the endothelium with cells of the immune system. Gene upregulation is mediated predominantly at the transcriptional level and in many cases involves the transcription factor nuclear factor (NF) kappa B. We have tested the concept of inhibiting the inflammatory response by overexp ression of a specific inhibitor of NF-kappa B, I kappa B alpha. A reco mbinant adenovirus expressing I kappa B alpha was constructed (rAd.I k appa B alpha) and used to infect EC ofhuman and porcine origin. Ectopi c expression of I kappa B alpha resulted in marked, and in some cases complete, reduction of the expression of several markers of EC activat ion, including vascular cell adhesion molecule 1, interleukins 1, 6, 8 , and tissue factor. Overexpressed I kappa B alpha inhibited NF-kappa B specifically since (a) in electrophoretic mobility shift assay, NF-k appa B but not AP-1 binding activity was inhibited, and (b) von Willeb rand factor and prostacyclin secretion that occur independently of NF- kappa B, remained unaffected. Functional studies of leukocyte adhesion demonstrated strong inhibition of HL-60 adhesion to I kappa B alpha-e xpressing EC. These findings suggest that NF-kappa B could be an attra ctive target for therapeutic intervention in a variety of inflammatory diseases, including xenograft rejection.