Adenoviral Vector Transfection into the Pulmonary Epithelium after Cecal Ligation and Puncture in Rats

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Abstract

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 hypothesis that adenoviral vector uptake after cecal ligation and double puncture in rats, an animal model of the acute respiratory distress syndrome, is higher than that observed in controls that did not undergo operation (“nonoperated”) or those that underwent a sham operation (“sham-operated”).

Methods

Adenoviruses expressing green fluorescent protein or Lac-Z were delivered into the lungs of anesthetized rats via tracheal catheter. Animals were killed 24 or 48 h 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 sectioning. Viral receptor density and localization were determined using immunoblotting and immunohistochemistry.

Results

After cecal ligation and double puncture, rats were hypoxic and tachypneic. Alveoli were segmentally consolidated, contained proteinaceous debris and neutrophils, and had thickened septa. Administration of adenoviruses to rats that were sham-operated or underwent cecal ligation and double puncture resulted in high levels of marker protein expression in cells lining alveoli. Use of 3 × 1011 plaque-forming units instead of 3 × 1012 plaque-forming units resulted in similar levels of green fluorescent protein expression with negligible viral-mediated lymphocytic infiltration. Semithin section and electron microscopy revealed expression primarily localized to type II alveolar cells. Abundance of αvβ3 integrins and human coxsackie–adenovirus receptor (receptors that modulate viral attachment and internalization) was increased after cecal ligation and double puncture, predominantly in type II pneumocytes.

Conclusions

Cecal ligation and double puncture induces histologic and functional changes consistent with the acute respiratory distress syndrome, increases surface expression of viral receptors, and enhances adenoviral-mediated gene transfer.

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