Adenoviral vector transfection into the pulmonary epithelium after cecal ligation and puncture in rats

Background: Adenoviral-targeted gene delivery to respiratory epithelium can augment production of specific proteins. Therefore, it may be valuable in treating the acute respiratory distress syndrome. The authors tested the hy pothesis that adenoviral vector uptake after cecal ligation and double punc ture in rats, an animal model of the acute respiratory distress syndrome, i s higher than that observed In controls that did not undergo operation ("no noperated") or those that under-went a sham operation ("sham-operated"). Methods: Adenoviruses expressing green fluorescent protein or Lac-Z were de livered into the lungs of anesthetized rats via tracheal catheter. Animals were killed 24 or 48 It later. Histopathology and green fluorescent protein expression were examined using light of fluorescence microscopy. Cellular localization of Lac-Z was determined with electron microscopy or semithin s ectioning. Viral receptor density and localization were determined using im munoblotting and immunohistochemistry. Results: After cecal ligation and double puncture, rats were hypoxic and ta chypneic. Alveoli were segmentally consolidated, contained proteinaceous de bris and neutrophils, and had thickened septa. Administration of adenovirus es to rats that were sham-operated or underwent cecal ligation and double p uncture resulted in high levels of marker protein expression in cells linin g alveoli. Use of 3 x 10(11) plaque-forming units instead of 3 X 10(12) pla que-forming units resulted In similar levels of green fluorescent protein e xpression with negligible viral-mediated lymphocytic infiltration. Semithin section and electron microscopy revealed expression primarily localized to type H alveolar cells. Abundance of alpha (v)beta (3) integrins and human coxsackie-adenovirus receptor (receptors that modulate viral attachment and internalization) was increased after cecal ligation and double puncture, p redominantly in type H pneumocytes. Conclusions: Cecal ligation and double puncture Induces histologic and func tional changes consistent with the acute respiratory distress syndrome, inc reases surface expression of viral receptors, and enhances adenoviral-media ted gene transfer.