Attenuation of Monocrotaline-Induced Pulmonary Hypertension by Luminal Adeno-Associated Virus Serotype 9 Gene Transfer of Prostacyclin Synthase

Abstract

Idiopathic pulmonary arterial hypertension (iPAH) is associated with high morbidity and mortality. We evaluated whether luminal delivery of the human prostacyclin synthase (hPGIS) cDNA with adeno-associated virus (AAV) vectors could attenuate PAH. AAV serotype 5 (AAV5) and AAV9 vectors containing the hPGIS cDNA under the control of a cytomegalovirus-enhanced chicken β-actin (CB) promoter or vehicle (saline) were instilled into lungs of rats. Two days later, rats were injected with monocrotaline (MCT, 60 mg/kg) or saline. Biochemical, hemodynamic, and morphologic assessments were performed when the rats developed symptoms (3-4 weeks) or at 6 weeks. Luminal (airway) administration of AAV5 and AAV9CBhPGIS vectors (MCT-AAV5 and MCT-AAV9 rats) significantly increased plasma levels of 6-keto-PGF1(α) as compared with MCT-controls, and closely resembled levels measured in rats not treated with MCT (saline-saline). Right ventricular (RV)/left ventricular (LV)+septum (S) ratios and RV systolic pressure (RVSP) were greater in MCT-control rats than in saline-saline rats, whereas the ratios and RVSP in MCT-AAV5CBhPGIS and MCT-AAV9CBhPGIS rats were similar to saline-saline rats. Thickening of the muscular media of small pulmonary arteries of MCT-control rats was detected in histological sections, whereas the thickness of the muscular media in MCT-AAV5CBhPGIS and MCT-AAV9CBhPGIS rats was similar to saline-saline controls. In experiments with different promoters, a trend toward increased levels of PGF1(α) expression was detected in lung homogenates, but not plasma, of MCT-treated rats transduced with an AAV9-hPGIS vector containing a CB promoter. This correlated with significant reductions in the RV/LV+S ratio and RVSP in MCT-AAV9CBhPGIS rats that resembled levels in saline-saline rats. No changes in levels of PGF1(α), RV/LV+S, or RVSP were detected in rats transduced with AAV9-hPGIS vectors containing a modified CB promoter (CB7) or a distal epithelial cell-specific promoter (CC10). Thus, AAV9CBhPGIS vectors prevented development of MCT-induced PAH and associated pulmonary vascular remodeling.