Gene Transfer of Extracellular Superoxide Dismutase to Atherosclerotic Mice

Abstract

Clinical and epidemiological studies have provided circumstantial evidence that oxidized low-density lipoprotein (LDL) and antioxidants are involved in the pathogenesis of atherosclerosis. Superoxide dismutases (SODs) have been shown in vitro to protect LDL from deleterious effects of superoxide anions. In the present study, we have used adenoviral gene transfer to determine effect of extracellular SOD (EC-SOD) on atherogenesis in LDL receptor -/- mice. Intravenous administration of EC-SOD adenovirus (2 x 10(9) plaque forming units) into tail vein targeted transgene mainly to liver and induced a 3.5- to sevenfold increase in plasma total SOD activity. EC-SOD was secreted into circulation for 2-3 weeks mostly in a truncated B-form, suggesting that endogenous proteolytic mechanisms control the level and distribution of the enzyme. Therapeutic potential was determined by measuring plasma resistance against copper oxidation and analyzing atherosclerotic lesion areas in aortas of LDL receptor -/- mice. Mice were kept on a cholesterol diet for 10 weeks before gene transfer and 3 or 6 weeks after the gene transfer. Results showed a tendency for a reduction in the overall lesion area after EC-SOD gene transfer as compared with LacZ transduced control mice, but the difference did not reach statistical significance. It is concluded that short-term overexpression of EC-SOD in vivo does not affect atherogenesis in LDL receptor -/- mice.

Genetically Reduced Antioxidative Protection and Increased Ischemic Heart Disease Risk

“…Gene transfer of EC-SOD into LDL receptor-null mice did not affect the extent of lesion formation even though plasma EC-SOD was increased 4-to 7-fold. 15 It should, however, be kept in mind that the extra EC-SOD expression transfected to these mice was added onto a normal physiological level. If physiological EC-SOD levels are sufficient to balance out oxidative stress from superoxide anions, increasing EC-SOD concentrations, even to excessive levels, cannot be expected to reduce atherogenesis.…”

Extracellular superoxide dismutase (ecSOD) in vascular biology: an update on exogenous gene transfer and endogenous regulators of ecSOD

“…-associated oxidative stress by enhancing ecSOD has been applied successfully in various experimental disease models [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] (Table I). For example, ecSOD has been shown to restore erectile function in streptozotocin-induced diabetes, 33 protect against vascular dysfunction with aging, 19 blunt ischemia/reperfusion-induced liver injury, 32 reduce systemic vascular resistance and arterial pressure in spontaneously hypertensive rats, 21 improve endothelial dysfunction in hypertension and in heart failure models, 23,35 and ameliorate inflammatory arthritis.…”

“…Conversely, in other cases, ecSOD gene therapy failed to protect against cardiovascular diseases (Table I). For example, Laukkanen et al 18 reported that short-term overexpression of ecSOD in vivo did not affect atherogenesis in LDL receptor −/− mice. Yamaguchi et al 24 showed that human ecSOD gene transfer failed to prevent cerebral vasospasm in a canine model of subarachnoid hemorrhage.…”

Adenovirus-Mediated Extracellular Superoxide Dismutase Gene Therapy Reduces Neointima Formation in Balloon-Denuded Rabbit Aorta

“…12 The method was specific for the transgene and did not amplify endogenous rabbit EC-SOD mRNA. The reaction conditions for reverse transcription were as follows: denaturation at 80°C for 10 minutes, random primer annealing at 25°C for 5 minutes, and first-strand synthesis at 60°C for 50 minutes.…”