Direct effects of alcohol on hepatic fibrinolytic balance: implications for alcoholic liver disease.

BACKGROUND/AIMS: The pathogenesis of alcoholic liver disease (ALD) remains uncertain. Fibrin production and degradation are altered in experimental liver injury. We have recently identified increased expression of a number of genes (annexin A2 (ANXA2), p11, tPA and PAI-1) that implicate fibrinolysis in ALD progression. Aim of our study was to study the direct effect of alcohol on fibrinolysis and plasmin activity in hepatic cell lines and in vivo.
METHODS: Expression of pro- and anti-fibrinolytic genes was determined in liver biopsies from patients with progressive ALD and in HepG2, Huh7 and LX-2 cells exposed to alcohol. The functional effects on fibrinolysis and plasmin activities were determined. C57BL6 female mice were given a single dose of alcohol and serum and liver triglyceride content and serum plasmin activity determined.
RESULTS: Alcohol induced a significant up-regulation of ANXA2, PLG, PAI-1 and p11 in human ALD, cell lines and in mice exposed to alcohol. Up-regulation of ANXA2 and p11 was inhibited by the alcohol dehydrogenase inhibitor 4-methylpyrazole. Fibrinolysis and plasmin were increased in HepG2 and LX-2 cells by 10mM alcohol and was inhibited by ANXA2 blocking antibody. Plasmin also increased in mice given a moderate dose of alcohol. By contrast, there was striking up-regulation of PAI-1 in mice given a high dose of alcohol with associated decrease in plasmin.
CONCLUSIONS: Alcohol directly alters hepatic expression of pro- and anti-fibrinolytic genes in a dose dependent manner with low dose promoting fibrinolysis and high dose inhibiting fibrinolysis. After a large dose of alcohol in vivo, the dominant effect was up-regulation of hepatic PAI-1 with suppression of plasmin. The effect of alcohol on fibrinolysis and plasmin is mediated in part by ANXA2. Alcohol directly influences hepatic pathways of fibrinolysis that may contribute to ALD.