fibrin and Liver-Diseases--Alcoholic

Plasminogen activator inhibitor-1 (PAI-1) is a major player in fibrinolysis due to its classical role of inhibiting plasminogen activators. Although increased fibrinolysis is common in alcoholic cirrhosis, decreased fibrinolysis (driven mostly by elevated levels of PAI-1) is common during the development of alcoholic liver disease (ALD). However, whether or not PAI-1 plays a causal role in the development of early ALD was unclear. Recent studies in experimental models have suggested that PAI-1 may contribute to the development of early (steatosis), intermediate (steatohepatitis) and late (fibrosis) stages of ALD. For example, fatty liver owing to both acute and chronic ethanol was blunted by the genetic inhibition of PAI-1. This effect of targeting PAI-1 appears to be mediated, at least in part, by an increase in very low-density lipoprotein (VLDL) synthesis in the genetic absence of this acute phase protein. Results from a two-hit model employing ethanol and lipopolysaccharide administration suggest that PAI-1 plays a critical role in hepatic inflammation, most likely due to its ability to cause fibrin accumulation, which subsequently sensitizes the liver to ensuing damaging insults. Lastly, the role of PAI-1 in hepatic fibrosis is less clear and appears that PAI-1 may serve a dual role in this pathological change, both protective (enhancing regeneration) and damaging (blocking matrix degradation). In summary, results from these studies suggest that PAI-1 may play multiple roles in the various stages of ALD, both protective and damaging. The latter effect is mediated by its influence on steatosis (i.e. decreasing VLDL synthesis), inflammation (i.e. impairing fibrinolysis) and fibrosis (i.e. blunting matrix degradation), whereas the former is mediated by maintaining hepatocyte division after an injury.

Topics: Animals; Disease Progression; Ethanol; Fatty Liver; Fibrin; Fibrinolysis; Humans; Lipopolysaccharides; Lipoproteins, VLDL; Liver; Liver Cirrhosis, Alcoholic; Liver Diseases, Alcoholic; Mice; Plasminogen Activator Inhibitor 1

Alcoholic liver disease (ALD) remains a leading cause of death from liver disease in the United States. In studies from the Veterans Administration, patients with cirrhosis and superimposed alcoholic hepatitis had greater than 60% mortality over a 4-year period, with most of those deaths occurring in the first month. Thus, the prognosis for this disease is more ominous than for many common types of cancer (eg, breast, prostate, and colon). Moreover, ALD imposes a significant economic burden from lost wages, health care costs, and lost productivity. Unfortunately, there is still no Food and Drug Administration-approved or widely accepted drug therapy for any stage of ALD. Thus, a pressing need exists for a more detailed understanding of mechanisms of liver injury. This article reviews recent advances in mechanisms and therapy related to five major areas of direct relevance to ALD: oxidative stress; gut-liver axis and cytokine signaling; malnutrition; fibrin/clotting; and stellate cell activation/fibrosis. We also review why therapies related to these mechanisms have performed well in experimental animals and in vitro systems, but have not necessarily translated into effective therapy for humans with ALD.

Topics: Blood Coagulation; Cytokines; Fibrin; Gastrointestinal Tract; Hepatic Stellate Cells; Humans; Liver Cirrhosis, Alcoholic; Liver Diseases, Alcoholic; Malnutrition; Oxidative Stress; Signal Transduction; Zinc

 Patients with cirrhosis may acquire profound changes in haemostasis. Although haemostatic changes in cirrhosis have been extensively studied, most studies were performed in groups of patients with mixed aetiology. As thrombotic events appear more common in some aetiologies of disease, notably non-alcoholic steatohepatitis (NASH) and cholestatic disease, we hypothesized that haemostatic changes might be different across aetiologies..  We studied 109 patients with cirrhosis (31 cholestatic liver disease, 23 NASH, 37 alcoholic liver disease [ALD], 18 viral hepatitis) and 44 healthy controls. Patients with malignancy were excluded. Routine diagnostic tests of haemostasis, thrombin generation assays, fibrin permeability assays and a plasma-based fibrinolytic assay were performed..  All patients had comparable severity of disease according to their Model for End-Stage Liver Disease score (9 [7-11]). Plasma levels of von Willebrand factor were substantially elevated across all aetiologies, with a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 levels comparable to controls. Thrombin generation capacity was elevated in all aetiologies, most profoundly in ALD. Fibrin permeability was decreased in all aetiologies, which was accompanied by elevated fibrinogen levels. Clot lysis times were prolonged in NASH and cholestatic disease. Plasma levels of individual proteins were similarly altered in all aetiologies..  Our in-depth haemostatic profiling of primary, secondary and tertiary haemostasis in a group of patients with Childs-Turcotte-Pugh A/B cirrhosis showed no large differences between aetiologies, and was consistent with a general hypercoagulable profile in patients with mild cirrhosis. These results suggest that patients with cirrhosis have an increased risk of thrombosis, irrespective of their aetiology.

Topics: Aged; Blood Coagulation; Blood Coagulation Tests; Case-Control Studies; Cholestasis; Female; Fibrin; Fibrinolysis; Fibrosis; Hemostasis; Hemostatics; Hepatitis; Humans; Liver Cirrhosis; Liver Diseases, Alcoholic; Male; Middle Aged; Partial Thromboplastin Time; Thrombin

The early stages of alcohol-induced liver injury involve chronic inflammation. Whereas mechanisms by which this effect is mediated are not completely understood, it is hypothesized that enhanced sensitivity to circulating lipopolysaccharide (LPS) contributes to this process. It has recently been shown that ethanol induces activation of plasminogen activator inhibitor-1 (PAI-1). PAI-1 causes fibrin accumulation in liver by inhibiting degradation of fibrin (fibrinolysis). LPS also enhances fibrin accumulation by activating the coagulation cascade. It was therefore hypothesized that ethanol will synergistically increase fibrin accumulation caused by LPS, enhancing liver damage. Accordingly, the effect of ethanol pretreatment on LPS-induced liver injury and fibrin deposition was determined in mice. Ethanol enhanced liver damage caused by LPS, as determined by plasma parameters and histological indices of inflammation and damage. This effect was concomitant with a significant increase in PAI-1 expression. Extracellular fibrin accumulation caused by LPS was also robustly increased by ethanol preexposure. Coadministration of the thrombin inhibitor hirudin or the MEK (mitogen-activated protein kinase) inhibitor U0126 significantly attenuated the enhanced liver damage caused by ethanol preexposure; this protection correlated with a significant blunting of the induction of PAI-1 caused by ethanol/LPS. Furthermore, thrombin/MEK inhibition prevented the synergistic effect of ethanol on the extracellular accumulation of fibrin caused by LPS. Similar protective effects on fibrin accumulation were observed in tumor necrosis factor receptor 1 (TNFR-1)(-/-) mice or in wild-type injected with PAI-1-inactivating antibody.. These results suggest that enhanced LPS-induced liver injury caused by ethanol is mediated, at least in part, by fibrin accumulation in livers, mediated by an inhibition of fibrinolysis by PAI-1. These results also support the hypothesis that fibrin accumulation may play a critical role in the development of early alcohol-induced liver injury.

Topics: Alcohol Drinking; Animals; Antithrombin III; Enzyme Activation; Ethanol; Extracellular Signal-Regulated MAP Kinases; Fibrin; Gene Expression Regulation; Lipid Metabolism; Lipopolysaccharides; Liver; Liver Diseases, Alcoholic; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Peptide Hydrolases; Plasminogen Activator Inhibitor 1; Receptors, Tumor Necrosis Factor, Type I; Triglycerides