REPLICATION-DEFICIENT ADENOVIRUS INDUCES EXPRESSION OF INTERLEUKIN-8 BY AIRWAY EPITHELIAL-CELLS IN-VITRO

Preclinical studies with first-generation adenovirus (Ad) vectors admi nistered in vivo to the respiratory tract have demonstrated a nonspeci fic host response consisting, in part, of parenchymal neutrophil accum ulation followed by mononuclear cell and macrophage accumulation, We h ypothesized that the mechanism for this host response might be the ela boration of interleukin-8 (IL-8) and monocyte chemoattractant protein- 1 (MCP-1) from the airway epithelium following the exposure to Ad, To evaluate this hypothesis, we infected A549 cells (a human-derived lung epithelial cell line) in vitro with an adenovirus type 5 (Ad5)-based vector expressing a nuclear targeted P-galactosidase enzyme (Av1LacZ4) . We found that cellular transduction was efficient, resulting in gene delivery to 85.5% +/- 3.9% of the cell monolayer after 96 hr, Importa ntly, IL-8 mRNA transcript levels in Av1LacZ4-transduced cells were si gnificantly higher than uninfected controls by 24 hr and remained elev ated for 96 hr, IL-8 protein secretion from Av1LacZ4-transduced cells was increased for the same period, The Av1LacZ4-transduced A549 cells also showed a neutrophil chemoattractant activity higher than control cells, measurable at 24 hr, and persisting for 96 hr, The chemoattract ant activity could be neutralized by a specific monoclonal antibody to IL-8. Whereas Av1LacZ4 transduction induced IL-8 gene expression, the re was a lack of expression of MCP-1 by A549 cells, These observations demonstrate that the gene delivery to the airway epithelium using the Ad5-based expression vector results in IL-8 gene activation in these cells, which may contribute to the described inflammatory host respons e,