High adenoviral loads stimulate NFκB-dependent gene expression in human vascular smooth muscle cells

Replication-deficient adenoviral vectors have been widely used for gene transfer with the aim of delivering genes of interest to investigate their function and potentially to treat human disease. The ability to critically evaluate the biological role of a gene of interest, using adenovirus-based vectors, has been hampered by the development of local inflammation at the site of delivery. We have demonstrated that high multiplicity infection of human VSMCs with a replication-deficient adenoviral vector expressing no transgene leads to activation of the transcription factor NFκB. Activation of NFκB by this mechanism was able to augment gene expression from the human cytomegalovirus immediate–early promoter (CMV-IEP) and induce expression of the adhesion molecule ICAM-1 in human VSMCs. These effects were inhibited by pretreatment with Nα-p-tosyl-L-lysine chloromethyl ketone (TLCK), a serine protease inhibitor known to inhibit the activation of NFκB. This important effect of the vector itself may have profound implications when replication-deficient adenoviral vectors are used for experimental gene transfer at a high multiplicity of infection.