Regulation of adenovirus-mediated elafin transgene expression by bacteriallipopolysaccharide

Lipopolysaccharide (LPS) is a mediator of inflammatory lung injury. Selecti ve augmentation of host defense molecules such as elafin (an elastase inhib itor with antimicrobial activity) at the onset of pulmonary inflammation is an attractive potential therapeutic strategy. The aim of this study was to determine whether elafin expression could be induced by LPS administered a fter transfection with adenovirus (Ad) encoding human elafin downstream of the murine cytomegalovirus (CMV) promoter (known to be potentially responsi ve to LPS). In addition, we aimed to determine the effect of local elafin a ugmentation on neutrophil migration to the lung. LPS significantly up-regul ated elafin expression from pulmonary epithelial cells transfected with Ad- elafin in vitro. In murine airways expression of human elafin was achieved using doses low enough (3 x 10(7) plaque forming units) to circumvent overt vector-induced inflammation. LPS significantly up-regulated human elafin s ecretion in murine airways treated with Ad-elafin [117 ng/ml in bronchoalve olar lavage fluid (BALF) after LPS administration, 5.9 ng/ml after PBS, p < 0.01)]. Over-expression of elafin significantly augmented LPS-mediated neu trophil migration into the airways in vivo (1.30 x 10(6) neutrophils in BAL F after Ad-elafin/LPS treatment, 0.54 x 10(6) after Ad-lacZ/LPS (p < 0.05), 0.63 x 10(6) after PBS/LPS (p < 0.05)) and significantly enhanced human ne utrophil migration in vitro. These data suggest novel functions for elafin in neutrophil migration, and that judicious selection of promoters may allo w single, low-dose adenoviral administration to effect inflammation-specifi c expression of potentially therapeutic transgenes.