Lack of plasminogen activator inhibitor-1 promotes growth and abnormal matrix remodeling of advanced atherosclerotic plaques in apolipoprotein E-deficient mice

Epidemiological studies suggest that elevated plasma levels of plasminogen activator inhibitor-1 (PAI-1) predispose an individual to ischemic heart disease or promote plaque progression by inhibiting fibrinolysis. In the present study, loss of PAI-1 in apolipoprotein E (apoE) -deficient (apoE(-/-):PAI-1(-/-)) mice promoted the growth of advanced atherosclerotic plaques, which was due to enhanced extracellular matrix deposition. ApoE(-/-):PAI-1(-/-) plaques also exhibited collagen fiber disorganization and degradation. Immunostaining and bone marrow transplantation revealed that smooth muscle cells, not macrophages, primarily expressed PAI-1 in plaques. Thus, although PAI-1 may promote plaque growth because of its antifibrinolytic properties, the present study reveals a protective role for PAI-1 by limiting plaque growth and preventing abnormal matrix remodeling.