ABSTRACT
Tracheal insufflation of chloramphenicol acetyltransferase (CAT) expression plasmid (pBL-CAT) DNA without any gene delivery system results in transfection of rat lungs (Am J Physiol. 1995;268:L1052-L1056). This study investigated the pulmonary response to tracheal insufflation of plasmid DNA and the immunohistochemical localization of transgene expression in the lungs. Insufflation of 300 micrograms pBL-CAT DNA resulted in lung transfection without causing pulmonary injury as judged from the protein content of alveolar lavage fluid, pleural effusion, and lung ultrastructure. There was, however, an acute alveolar inflammatory response at 6 h after insufflation due to contaminating endotoxin present in the plasmid DNA preparation. Reducing the amount of endotoxin from 0.022 to 0.0015 microgram per 300 micrograms pBL-CAT completely abolished the acute alveolar inflammatory response without affecting the lung transfecting efficiency of pBL-CAT. Immunohistochemistry revealed that insufflation of pBL-CAT transfected predominantly small airway epithelial cells.
Subject(s)
DNA/administration & dosage , DNA/metabolism , Lung/metabolism , Plasmids/genetics , Transgenes , Animals , Chloramphenicol O-Acetyltransferase/genetics , Chloramphenicol O-Acetyltransferase/metabolism , DNA/genetics , Gene Expression , Immunohistochemistry , Lipopolysaccharides/toxicity , Liposomes , Lung/ultrastructure , Male , Plasmids/administration & dosage , Rats , Rats, Sprague-Dawley , Trachea/physiology , Transfection/methodsABSTRACT
Pulmonary superoxide dismutase (SOD) plays an important role in the lung defense against O2 toxicity. We have previously demonstrated that tracheal insufflation of interleukin-1 alpha (IL-1) selectively enhances pulmonary MnSOD and protects rats against O2 toxicity. However, little is known about the cellular distribution of pulmonary MnSOD- and CuZnSOD-specific proteins. We performed immunohistochemistry in plastic sections (2 microns thick) to determine the effects of hyperoxia and IL-1 on the cellular distribution of pulmonary MnSOD and CuZnSOD in rats. MnSOD and CuZnSOD were present in all lung cells. Smooth muscle and endothelial cells appeared to contain higher immunoreactive MnSOD and CuZnSOD proteins than other lung cell types. Exposure of rats to 100% O2 for 24 hr had no effect on the cellular distribution and intensity of pulmonary MnSOD. However, at 50 hr after O2 exposure the intensity of pulmonary MnSOD was reduced. In contrast, tracheal insufflation of IL-1 markedly enhanced the intensity of pulmonary MnSOD in rats exposed to O2 for 50 hr. Neither O2 exposure nor IL-1 insufflation had any apparent effect on the distribution and intensity of pulmonary CuZnSOD. We conclude that IL-1 selectively enhances pulmonary MnSOD and that this effect is manifested in most lung cells, particularly smooth muscle and endothelial cells.
