Pharmacological inhibition and genetic deficiency of plasminogen activator inhibitor-1 attenuates angiotensin II/salt-induced aortic remodeling.

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.

Lack of plasminogen activator inhibitor-1 enhances the preventive effect of DX-9065a, a selective factor Xa inhibitor, on venous thrombus and acute pulmonary embolism in mice.

We have studied the physiological effects of DX-9065a, a selective factor Xa (FXa) inhibitor, and heparin in experimental venous thrombus and acute pulmonary embolism. Moreover, the effects of these compounds were also evaluated under the condition of plasminogen activator inhibitor-1 (PAI-1) deficiency. A thrombus was induced in the murine femoral vein. The compounds prolonged the time to occlusion in a dose-dependent manner. Pulmonary embolism was induced by continuous induction of venous thrombi in the left jugular vein. The mortality of mice increased time-dependently. Histological evidence of thromboembolism in the lung was obtained in all mice. Treatment with DX-9065a, but not heparin, reduced the mortality at 6 h after initiation of venous thrombi. In separate experiments, pulmonary thromboembolism was induced in PAI-1 knockout mice. The mortality in PAI-1 knockout mice was reduced compared with that of wild-type mice. Moreover, when DX- 9065a was administered to PAI-1 knockout mice with pulmonary thromboembolism, mice survived well without marked bleeding. These findings indicate that the dual inhibition of coagulation FXa and PAI-1 could be beneficial in the treatment of acute pulmonary embolism.

Role of plasminogen system components in focal cerebral ischemic infarction: a gene targeting and gene transfer study in mice.

BACKGROUND: The role of plasminogen system components in focal cerebral ischemic infarction (FCI) was studied in mice deficient in plasminogen (Plg-/-), in tissue or urokinase plasminogen activator (tPA-/- or uPA-/-), or in plasminogen activator inhibitor-1 or alpha2-antiplasmin (PAI-1(-/-) or alpha2-AP-/-). METHODS AND RESULTS: FCI was produced by ligation of the left middle cerebral artery and measured after 24 hours by planimetry of stained brain slices. In control (wild-type) mice, infarct size was 7.6+/-1.1 mm3 (mean+/-SEM), uPA-/- mice had similar infarcts (7.8+/-1.0 mm3, P=NS), tPA-/- mice smaller (2.6+/-0.80 mm3, P<0.0001), PAI-1(-/-) mice larger (16+/-0.52 mm3, P<0.0001), and Plg-/- mice larger (12+/-1.2 mm3, P=0.037) infarcts. alpha2-AP-/- mice had smaller infarcts (2. 2+/-1.1 mm3, P<0.0001 versus wild-type), which increased to 13+/-2.5 mm3 (P<0.005 versus alpha2-AP-/-) after intravenous injection of human alpha2-AP. Injection into alpha2-AP-/- mice of Fab fragments of affinospecific rabbit IgG against human alpha2-AP, after injection of 200 microg human alpha2-AP, reduced FCI from 11+/-1.5 to 5.1+/-1.1 mm3 (P=0.004). CONCLUSIONS: Plg system components affect FCI at 2 different levels: (1) reduction of tPA activity (tPA gene inactivation) reduces whereas its augmentation (PAI-1 gene inactivation) increases infarct size, and (2) reduction of Plg activity (Plg gene inactivation or alpha2-AP injection) increases whereas its augmentation (alpha2-AP gene inactivation or alpha2-AP neutralization) reduces infarct size. Inhibition of alpha2-AP may constitute a potential avenue to treatment of FCI.