The objective of this study was to determine whether overexpression of human extracellular superoxide dismutase (hEC-SOD) can preserve nitric oxide (NO) bioavailability. In vitro studies examined the transient expression of hEC-SOD in mouse epithelial (C10) cells and its effect on extracellular accumulation of NO, intracellular cyclic guanosine monophosphate (cGMP), and nuclear factor kappa B (NF-κB) activation under normal and oxidative stress conditions. In vivo, newborn rabbits were treated with a plasmid containing hEC-SOD cDNA or vehicle plasmid alone, followed by exposure to hyperoxia (Fio2 = 95% for 7 days). A third group was raised under normoxic conditions. cGMP and NF-κB activation were studied. There was significantly higher NO accumulation in cells expressing hEC-SOD exposed to oxidative stress compared with nontransfected cells. Accumulation of cGMP was significantly higher in cells expressing hEC-SOD. Oxidative stress induced NF-κB activation, which was abrogated by hEC-SOD expression. In vivo, there was significantly higher cGMP accumulation in transfected neonatal rabbit lung tissue at 3 and 7 days of hyperoxic exposure. Immunostaining for NF-κB, showed a marked increase in NF-κB concentration in nontreated neonatal rabbit lung tissue compared to transfected neonatal lung with hEC-SOD and the control air group. These results show that transient EC-SOD overexpression maintains NO bioavailability, which directly leads to maintenance of cGMP activity and reduction of NF-κB activation under oxidative stress.
- oxidative stress
ASJC Scopus subject areas
- Molecular Biology
- Pulmonary and Respiratory Medicine
- Clinical Biochemistry