Effect of angiotensin II on plasminogen activator inhibitor-1 production by cultured human mesangial cells

Angiotensin II is a vasoactive peptide that has been widely implicated in the pathogenesis of glomerular disease. Some of its effects are thought to be independent of changes in blood pressure. Plasmin is a key regulator of fibrinolysis and extracellular matrix turnover. The conversion of plasminogen to plasmin by plasminogen activators (PAs) is controlled by their specific inhibitor, PAI-1. In this study we report the effects of angiotensin II on the production of PA inhibitor-1 (PAI-1) and tissue-type PA (t-PA) by glomerular mesangial cells in culture. Angiotensin II significantly increased the production of PAI-1 in the supernatant of mesangial cells (p < 0.05) in a dose-dependent manner, the maximum stimulation occurring at a concentration of 10(-5) M. The effect was not mediated by transforming growth factor-beta (TGF-beta), which is known to be induced by angiotensin II; TGF-beta itself can increase PAI-1 expression. Angiotensin II did not alter t-PA production or incorporation of matrix fibronectin but did increase cellular proliferation and H-3-thymidine uptake. The increase in PAI-1 by angiotensin II may contribute to the persistence of fibrin deposits and extracellular matrix accumulation, providing another mechanism whereby angiotensin II contributes to glomerular dysfunction.