Pretreatment with cationic lipid-mediated transfer of the Na+K+-ATPase pump in a mouse model in vivo augments resolution of high permeability pulmonary oedema

Resolution of pulmonary oedema is mediated by active absorption of liquid a cross the alveolar epithelium. A key component of this process is the sodiu m-potassium ATPase (Na+K+-ATPase) enzyme located on the basolateral surface of epithelial cells and up-regulated during oedema resolution. We hypothes ised that lung liquid clearance could be further up-regulated by lipid-medi ated transfer and expression of exogenous Na+K+-ATPase cDNA. We demonstrate proof of this principle in a model of high permeability pulmonary oedema i nduced by intraperitoneal injection of thiourea (2.5 mg/kg) in C57/BL6 mice . Pretreatment of mice (24 h before thiourea) by nasal sniffing of cationic liposome (lipid #67)-DNA complexes encoding the alpha and beta subunits of Na+K+-ATPase (160 mu g per mouse), significantly (P < 0.01) decreased the wet:dry weight ratios measured 2 h after thiourea injection compared with c ontrol animals, pretreated with an equivalent dose of an irrelevant gene. W hole lung Na+K+-ATPase activity was significantly (P < 0.05) increased in m ice pretreated with Na+K+-ATPase cDNA compared both with untreated control animals as well as animals pretreated with the irrelevant gene. Nested RT-P CR on whole lung homogenates confirmed gene transfer by detection of vector -specific mRNA in three of four mice studied 24 h after gene transfer. This demonstration of a significant reduction in pulmonary oedema following in vivo gene transfer raises the possibility of gene therapy as a novel, local ised approach for pulmonary oedema in clinical settings such as ARDS and lu ng transplantation.