Pharmacological Targeting of Plasminogen Activator Inhibitor-1 Decreases Vascular Smooth Muscle Cell Migration and Neointima Formation.

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 antimigratory effects were PAI-1-specific and physiologically relevant. However, PAI-039 did not inhibit EC migration. PAI-039 inhibited phosphorylation and nuclear translocation of signal transducers and activators of transcription-1 in SMCs, but had no discernable effect on signal transducer and activator of transcription-1 signaling in ECs. Expression of low-density lipoprotein receptor-related protein 1, a motogenic PAI-1 receptor that activates Janus kinase/signal transducers and activators of transcription-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 seems to be because of differences in PAI-1-dependent low-density lipoprotein receptor-related protein 1/Janus kinase/signal transducer and activator of transcription-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.

Different mechanisms for histone acetylation by ethanol and its metabolite acetate in rat primary hepatocytes.

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, PPARγ, 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.