Background and objective
Idiopathic, familial and secondary pulmonary arterial hypertension (PAH) are associated with reduced bone morphogenetic protein receptor type 2 (BMPR2) expression, and in some contexts, TGF‐β upregulation. Our aims were to assess BMPR2 gene therapy in a PAH mouse model and to assess the impact on TGF‐β signalling.
Methods
Using a targeted in vivo gene delivery approach, we assessed the impact of BMPR2 gene delivery in a transgenic mouse model in which PAH was first induced by doxycycline driven expression of a dominant negative BMPR2 mutant (R899X). We also assessed the impact of BMPR2 gene delivery on TGF‐β‐induced changes in cell signalling in human pulmonary vascular endothelial and smooth muscle cells.
Results
In the mouse model, changes in TGF‐β levels were not detected, but BMPR2 gene delivery reversed the increase in right ventricle systolic pressure (RVSP) and Fulton Index (FI), associated with a trend to increased pulmonary endothelial nitric oxide synthase (eNOS) gene expression. In vitro, BMPR2 gene transfer reduced TGF‐β effects on Smad2, Smad1/5/8 and Erk1/2 phosphorylation in human pulmonary arterial smooth muscle cells (HPASMC). BMPR2 was also found to upregulate nitric oxide (NO) production in lung derived human microvascular endothelial cells (HMVEC‐L).
Conclusion
This study provides further evidence that BMPR2 modulation may have therapeutic potential.
See Editorial, page 406