Gene transfer of extracellular superoxide dismutase ameliorates pulmonary hypertension in rats

Rationale: Pulmonary hypertension (PH) is a life-threatening disease, characterized by vascular remodeling and vasoconstriction. Evidence suggests that oxidative stress may contribute to the pathogenesis and/or development of PH. Objectives: In the present study, we examined whether intratracheal gene transfer of human extracellular superoxide dismutase (EC-SOD) could ameliorate monocrotaline (MCT)-induced PH in rats. Methods: MCT-injected rats were intratracheally administered vehicle (MCT group) or an adenovirus encoding beta-galactosidase (Ad beta gal group) or human EC-SOD (AdEC-SOD group). Measurements and Main Results: After intratracheal gene transfer, EC-SOD was successfully expressed in lung tissue, bronchoalveolar lavage fluid, and plasma. Twenty-eight days after MCT injection, right ventricular systolic pressure and the weight ratio of the right ventricle to the left ventricle plus septum were significantly lower in the AdEC-SOD group (42.50 +/- 1.46 mm Hg and 0.453 +/- 0.029, respectively) than in the MCT group (59.89 +/- 1.61 mm Hg and 0.636 +/- 0.022, respectively) or the Ad beta gal group (61.50 +/- 2.61 mm Hg and 0.653 +/- 0.038, respectively). Moreover, vascular remodeling and proliferation of vascular smooth muscle cells in pulmonary arteries were markedly suppressed in the AdEC-SOD group. Importantly, 8-isoprostane in lung tissue was also significantly reduced in the AdEC-SOD group. Conclusions: EC-SOD overexpression to the lung ameliorated MCT-induced PH in rats. We suggest that EC-SOD may act as an antioxidant in PH and that increased oxidative stress may be important in the pathogenesis of MCT-induced PH.