OBJECTIVE - To test the hypothesis that pharmacological plasminogen activator inhibitor (PAI)-1 inhibition protects against renin-angiotensin-aldosterone system-induced cardiovascular injury, the effect of a novel orally active small-molecule PAI-1 inhibitor, PAI-039, was examined in a mouse model of angiotensin (Ang) II-induced vascular remodeling and cardiac fibrosis.
METHODS AND RESULTS - Uninephrectomized male C57BL/6J mice were randomized to vehicle subcutaneus, Ang II (1 mug/h) subcutaneous, vehicle+PAI-039 (1 mg/g chow), or Ang II+PAI-039 during high-salt intake for 8 weeks. Ang II caused significant medial, adventitial, and aortic wall thickening compared with vehicle. PAI-039 attenuated Ang II-induced aortic remodeling without altering the pressor response to Ang II. Ang II increased heart/body weight ratio and cardiac fibrosis. PAI-039 did not attenuate the effect of Ang II on cardiac hypertrophy and increased fibrosis. The effect of PAI-039 on Ang II/salt-induced aortic remodeling and cardiac fibrosis was comparable to the effect of genetic PAI-1 deficiency. Ang II increased aortic mRNA expression of PAI-1, collagen I, collagen III, fibronectin, osteopontin, monocyte chemoattractant protein-1, and F4/80; PAI-039 significantly decreased the Ang II-induced increase in aortic osteopontin expression at 8 weeks.
CONCLUSIONS - This study demonstrates that pharmacological inhibition of PAI-1 protects against Ang II-induced aortic remodeling. Future studies are needed to determine whether the interactive effect of Ang II/salt and reduced PAI-1 activity on cardiac fibrosis is species-specific. In this study, the effect of pharmacological PAI-1 inhibition in a mouse model of Ang II-induced vascular remodeling and cardiac fibrosis was examined. PAI-1 inhibition significantly attenuated Ang II-induced aortic medial and wall thickening, but not cardiac hypertrophy, and enhanced Ang II/salt-induced cardiac fibrosis.