Comparison of the Effect of Adenoviral Delivery of Three Superoxide Dismutase Genes Against Hepatic Ischemia-Reperfusion Injury

Abstract

The purpose of this study was to investigate the effectiveness of superoxide dismutase (SOD) overexpression in an acute model of hepatic oxidative stress. Oxidative stress was established using a warm ischemia-reperfusion model, where nearly 70% of the liver was made hypoxic by clamping the hepatic artery and a branch of the portal vein for 1 hr followed by restoration of blood flow. Animals were infected i.v. with 1 x 10(9) plaque-forming units (PFU) of adenovirus containing the transgene for cytosolic Cu/Zn-SOD (Ad.SOD1), mitochondrial Mn-SOD (Ad.SOD2), extracellular Cu/Zn-SOD (Ad.SOD3), or the bacterial reporter gene for beta-galactosidase (Ad.lacZ) 3 days prior to experiments. Ad.SOD1 and Ad.SOD2 caused a three-fold increase in SOD expression and activity in liver compared to Ad.lacZ-treated control animals. Intravenous administration of Ad.SOD3 increased SOD activity slightly in serum but not in liver. Increases in serum transaminases and pathology due to ischemia-reperfusion were blunted by Ad.SOD1 and Ad.SOD2; however, extracellular SOD had no significant effect. Moreover, lipid-derived free radical adducts (a(N) = 15.65 G and a(H)(beta) = 2.78 G) were increased by ischemia-reperfusion. This effect was blunted by about 60% in Ad.SOD1- and Ad.SOD2-infected animals, but was unaffected by Ad.SOD3. However, when high doses of Ad.SOD3 (3 x 10(10) PFU) were administered. serum SOD activity was elevated three-fold and was protective against hepatic ischemia-reperfusion injury under these conditions. These data demonstrate that adenoviral delivery of superoxide dismutase can effectively reduce hepatic oxidative stress.

Manganese superoxide dismutase suppresses hypoxic induction of hypoxia-inducible factor-1α and vascular endothelial growth factor

“…In support of this proposal, Wheeler et al (2003) have shown that adenovirus transduction of SOD3 (extracellular SOD or ecSOD) inhibits the growth of B16 melanoma cells in mice. At 2 weeks after implantation, B16 tumor size was 65% smaller in mice infected with AdecSOD in comparison with mice infected with AdlacZ.…”

Redox therapeutics in hepatic ischemia reperfusion injury

“…This study found only partial protection from IRI implicating a significant role for other ROS or highlighting the weakness that this therapy cannot target the intracellular effects of ROS. Subsequent studies have utilized carbohydrate modifications of these enzymes or gene delivery to up regulate the intracellular activity of these enzymes and have shown potential benefit and cause for further investigation [50,51] .…”

Antioxidant gene therapy and hepatic ischemia-reperfusion injury

“…8 Furthermore, deleting viral genes can reduce the immunogenicity and toxicity, which allows for higher vector delivery with more prolonged persistence. 10 Using such recombinant adenovirus vectors, Wheeler et al 11 were able to deliver human superoxide dismutase genes (Ad.SOD1, Ad.SOD2) to liver cells and protect against hepatic ischemia-reperfusion injury. The authors confirmed and significantly expanded previous work by Engelhardt and coworkers with MnSOD (SOD2).…”

“…Interestingly, both interventions were equally protective. 11 The investigators did not evaluate in which liver cell types the viral vectors were present. Although adenoviruses enter hepatocytes, these viruses will also infect Kupffer cells.…”

“…An attenuated inflammatory response limits reperfusion injury. 2 However, Wheeler et al 11 also showed that intramuscular injection of Ad.SOD3 (extracellular SOD) substantially increased plasma SOD3 levels and that this novel intervention also protected against hepatic ischemia-reperfusion injury in vivo. This finding suggests that at least some of the reactive oxygen species generated by Kupffer cells in the vasculature and neutrophils in the extracellular space subsequently entered hepatocytes and caused cell injury.…”