Objective Plasminogen activator inhibitor-1 (PAI-1), a serine protease inhibitor that promotes and inhibits cell migration, plays a complex and important role in adverse vascular remodeling. Little is known about the effects of pharmacological PAI-1 inhibitors, an emerging drug class, on migration of vascular smooth muscle cells (SMCs) and endothelial cells (ECs), crucial mediators of vascular remodeling. We investigated the effects of PAI-039 (tiplaxtinin), a specific PAI-1 inhibitor, on SMC and EC migration in vitro and vascular remodeling in vivo. Approach and Results PAI-039 inhibited SMC migration through collagen gels, including those supplemented with vitronectin and other extracellular matrix proteins, but did not inhibit migration of PAI-1-deficient SMCs, suggesting that its anti-migratory effects were PAI-1-specific and physiologically relevant. However, PAI-039 did not inhibit EC migration. PAI-039 inhibited phosphorylation and nuclear translocation of STAT-1 in SMCs, but had no discernable effect on STAT-1 signaling in ECs. Expression of LDL receptor-related protein 1 (LRP1), a motogenic PAI-1 receptor that activates JAK/STAT-1 signaling, was markedly lower in ECs than in SMCs. Notably, PAI-039 significantly inhibited intimal hyperplasia and inflammation in murine models of adverse vascular remodeling, but did not adversely affect re-endothelialization after endothelium-denuding mechanical vascular injury. Conclusions PAI-039 inhibits SMC migration and intimal hyperplasia, while having no inhibitory effect on ECs, which appears to be due to differences in PAI-1-dependent LRP1/JAK/STAT-1 signaling between SMCs and ECs. These findings suggest that PAI-1 may be an important therapeutic target in obstructive vascular diseases characterized by neointimal hyperplasia.

Ethanol and its major metabolite acetate both induced histone H3 acetylation in primary culture of rat hepatocytes. The acetylation by ethanol was dependent on the reactive oxygen species and mitogen-activated protein kinase pathway, whereas that by acetate was independent of both pathways. Ethanol increased CYP2E1 protein expression but acetate had negligible effect. The level of phospho-H2AX, an indicator of DNA breaks, was elevated by ethanol but not by acetate. Ethanol and acetate differentially activated mRNA expression for different genes, e.g., IL-6, PPARg, c-Fos, Egr-1, and PNPLA3 in hepatocytes. The most striking increase (3-fold) was in PNPLA3 mRNA by ethanol with little change by acetate. It was further shown that acetate inhibited histone deacetylase activity. Taken together, these data establish for the first time that ethanol and acetate exhibit differences in their effects on hepatocytes in gene expression, P-H2AX levels, and the mechanism of histone H3 acetylation. The implications of these differences in the actions of ethanol in liver are discussed.

Summary Background C-reactive protein (CRP) promotes tissue factor (TF) and plasminogen activator inhibitor-1 (PAI-1) expression in vitro, and elevated plasma CRP concentration is associated with increased risk of vein graft (VG) thrombosis after coronary artery bypass surgery. However, little is known about the effects of CRP on VG TF and PAI-1 expression in vivo, or on VG thrombosis. Objectives We studied transgenic (Tg) mice expressing human CRP in a VG model to explore in vivo cause-and-effect relationships between CRP and TF, PAI-1, and VG thrombosis. Methods Vein segments from WT and CRP-Tg donors were transplanted into carotid arteries of WT and CRP-Tg recipients. VGs were analyzed 1-4 weeks later. Results Human CRP accumulated in VGs during the first 4 weeks after surgery, but appeared to originate exclusively from systemic sources, rather than local production. Human CRP significantly increased TF gene expression, protein concentration, and activity in VGs. Human CRP also increased PAI-1 concentration in VGs, though only in vascular endothelial cells. Human CRP stimulated macrophage migration, invasion into VGs, and TF expression. Fibrin deposition was significantly greater in VGs of CRP-Tg mice compared to WT controls. Conclusions CRP accumulates in VGs early after surgery, originating from systemic sources rather than local synthesis. Human CRP promotes TF and PAI-1 expression in VGs, though with different expression patterns. Human CRP stimulates macrophage invasion and fibrin deposition within VGs. These results suggest that CRP induces pathological changes in VGs that contribute to early VG occlusion.

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