New role of plasminogen activator inhibitor-1 in alcohol-induced liver injury

Noninvasive Biomarkers for Alcohol-Related Liver Disease-A Proteomic Related Preliminary Report

Increased alcohol intake over decades leads to progressive alcohol-related liver disease (ALD) and contributes to increased mortality. It is characterized by reduced platelet count. Platelets have a role in protecting vascular integrity and involved in liver regeneration. Alcohol affects the platelet count and its function. Platelet function is regulated by their proteins, released during pathophysiological conditions. Therefore, platelet proteome plays a vital role during ALD. This preliminary study consists of 10 patients with ALD. It includes the preparation of human platelets for the proteomic approach. We performed liquid chromatography-mass spectrometry for the samples. A total of 536 proteins were identified in patients with ALD of which 31 proteins were mentioned as a candidate based on their clinical significance. The advancement of diagnostic or therapeutic tools based on the application of platelet proteins in ALD is still far off. Platform for platelet and its proteome research may give diagnostic and prognostic insights into ALD. Platelet proteomes could possibly be concluded as therapeutic and potential diagnostic or prognostic markers in ALD.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12291-023-01120-9.

Inflammatory liver diseases and susceptibility to sepsis

Patients with inflammatory liver diseases, particularly alcohol-associated liver disease and metabolic dysfunction-associated fatty liver disease (MAFLD), have higher incidence of infections and mortality rate due to sepsis. The current focus in the development of drugs for MAFLD is the resolution of non-alcoholic steatohepatitis and prevention of progression to cirrhosis. In patients with cirrhosis or alcoholic hepatitis, sepsis is a major cause of death. As the metabolic center and a key immune tissue, liver is the guardian, modifier, and target of sepsis. Septic patients with liver dysfunction have the highest mortality rate compared with other organ dysfunctions. In addition to maintaining metabolic homeostasis, the liver produces and secretes hepatokines and acute phase proteins (APPs) essential in tissue protection, immunomodulation, and coagulation. Inflammatory liver diseases cause profound metabolic disorder and impairment of energy metabolism, liver regeneration, and production/secretion of APPs and hepatokines. Herein, the author reviews the roles of (1) disorders in the metabolism of glucose, fatty acids, ketone bodies, and amino acids as well as the clearance of ammonia and lactate in the pathogenesis of inflammatory liver diseases and sepsis; (2) cytokines/chemokines in inflammatory liver diseases and sepsis; (3) APPs and hepatokines in the protection against tissue injury and infections; and (4) major nuclear receptors/signaling pathways underlying the metabolic disorders and tissue injuries as well as the major drug targets for inflammatory liver diseases and sepsis. Approaches that focus on the liver dysfunction and regeneration will not only treat inflammatory liver diseases but also prevent the development of severe infections and sepsis.

Resolvin D1 attenuated liver injury caused by chronic ethanol and acute LPS challenge in mice

Alcohol-associated liver disease (ALD) is a major health problem with limited effective treatment options. Alcohol-associated hepatitis (AH) is a subset of severe ALD with a high rate of mortality due to infection, severe inflammation, and ultimately multi-organ failure. There is an urgent need for novel therapeutic approaches to alleviate the human suffering associated with this condition. Resolvin D1 (RvD1) promotes the resolution of inflammation and regulates immune responses. The current study aimed to test the therapeutic efficacy and mechanisms of RvD1-mediated effects on liver injury and inflammation in an experimental animal model that mimics severe AH in humans. Our data demonstrated that mice treated with RvD1 had attenuated liver injury and inflammation caused by EtOH and LPS exposure by limiting hepatic neutrophil accumulation and decreasing hepatic levels of pro-inflammatory cytokines. In addition, RvD1 treatment attenuated hepatic pyroptosis, an inflammatory form of cell death, via downregulation of pyroptosis-related genes such as GTPase family member b10 and guanylate binding protein 2, and reducing cleavage of caspase 11 and gasdermin-D. In vitro experiments with primary mouse hepatocytes and bone marrow-derived macrophages confirmed the effectiveness of RvD1 in the attenuation of pyroptosis. In summary, our data demonstrated that RvD1 treatment provided beneficial effects against liver injury and inflammation in an experimental animal model recapitulating features of severe AH in humans. Our results suggest that RvD1 may be a novel adjunct strategy to traditional therapeutic options for AH patients.

"Super" SERPINs-A stabilizing force against fibrinolysis in thromboinflammatory conditions

The superfamily of serine protease inhibitors (SERPINs) are a class of inhibitors that utilise a dynamic conformational change to trap and inhibit their target enzymes. Their powerful nature lends itself well to regulation of complex physiological enzymatic cascades, such as the haemostatic, inflammatory and complement pathways. The SERPINs α2-antiplasmin, plasminogen-activator inhibitor-1, plasminogen-activator inhibitor-2, protease nexin-1, and C1-inhibitor play crucial inhibitory roles in regulation of the fibrinolytic system and inflammation. Elevated levels of these SERPINs are associated with increased risk of thrombotic complications, obesity, type 2 diabetes, and hypertension. Conversely, deficiencies of these SERPINs have been linked to hyperfibrinolysis with bleeding and angioedema. In recent years SERPINs have been implicated in the modulation of the immune response and various thromboinflammatory conditions, such as sepsis and COVID-19. Here, we highlight the current understanding of the physiological role of SERPINs in haemostasis and inflammatory disease progression, with emphasis on the fibrinolytic pathway, and how this becomes dysregulated during disease. Finally, we consider the role of these SERPINs as potential biomarkers of disease progression and therapeutic targets for thromboinflammatory diseases.

Comparison of plasminogen activator inhibitor-1 levels in chronic hepatitis B patients with hepatic cirrhosis and without hepatic cirrhosis

Introduction: One of the hepatic cirrhosis manifestations is bleeding disorders. Among all the substance that plays a pivotal role in maintaining the balance between thrombosis and thrombolysis is PAI-1, synthesized by hepatocytes. The dynamics of increase and decrease of PAI-1 is a natural response to the ongoing hepatic cirrhosis, but may not be seen in non-hepatic cirrhosis. PAI-1 levels also depends on the stage of fibrosis. Several conditions may interfere with PAI-1 levels including age, body mass index, and gender Objectives: This study aims to find out the comparison of PAI-1 levels in hepatitis B patients with hepatic cirrhosis and without hepatic cirrhosis and to compare it with every stage of hepatic cirrhosis. Patients and Methods: This study is an observational analytical study with a cross-sectional approach conducted at Wahidin Sudirohusodo hospitals, Makassar. Subjects are chronic hepatitis B patients with and without hepatic cirrhosis which meet inclusion criteria. Serum PAI-1 levels were measured by using Bender MedSystems human plasminogen activator inhibitor-1 ELISA kit (BMS2033) and using the ELISA technique. Statistical analysis was performed using the Kolmogorov Smirnov normality test as well as the Mann-Whitney method. Statistical results are considered significant if the p-value <0.05. Results: The research was conducted on 60 subjects who meet inclusion criteria, consisting of 33 men and 27 women. There were 16 patients with hepatic cirrhosis. Levels of PAI-1 in hepatic cirrhosis was significantly different which lower than non-hepatic cirrhosis patient (0.43 ng/mL Vs 1.11 ng/mL, p=0.024).  By staging of hepatic fibrosis, stage F2 hepatic fibrosis had the highest levels of PAI-1, in contrast with end-stage hepatic fibrosis which had the lowest levels. Conclusion: Levels of PAI-1 fluctuate through different stages of hepatic fibrosis. The significant difference in PAI-1 levels in hepatic cirrhosis and non-hepatic cirrhosis demonstrates a correlation between PAI-1 and hepatic cirrhosis  Keywords: Chronic hepatitis B, Hepatic cirrhosis, Plasminogen Activator Inhibitor-1

Hepatoprotective Effect of Oyster Peptide on Alcohol-Induced Liver Disease in Mice

Alcohol-induced liver disease (ALD) has become one of the major global health problems, and the aim of this study was to investigate the characterization of the structure as well as the hepatoprotective effect and mechanism of oyster peptide (OP, MW < 3500 Da) on ALD in a mouse model. The results demonstrate that ethanol administration could increase the activities of aspartate aminotransferase (AST), alanine transaminase (ALT), γ-Glutamyl transferase (GGT), reactive oxygen species (ROS), malondialdehyde (MDA), and triglycerides (TG), as well as increase the interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor (TNF-α) levels (p < 0.01), and reduce the activity of superoxide dismutase (SOD) and the concentration of glutathione (GSH). Those changes were significantly reversed by the application of different doses of OP. Furthermore, the mRNA expressions of nuclear factor elythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), and quinone oxidoreductase1 (NQO1) were significantly up-regulated in OP groups, and the mRNA expressions of nuclear factor kappa-light chain enhancer of B cells (NF-κB), TNF-α, and IL-6 were markedly reduced in OP groups compared to that of the model group. Thus, OP had a significant protective effect on ALD through the enhancement of the in vivo antioxidant ability and the inhibition of the inflammatory response as possible mechanisms of action, which therefore suggests that OP might be useful as a natural source to protect the liver from alcohol damage.

A Novel Humanized Model of NASH and Its Treatment With META4, A Potent Agonist of MET

BACKGROUND & AIMS

Nonalcoholic fatty liver disease is a frequent cause of hepatic dysfunction and is now a global epidemic. This ailment can progress to an advanced form called nonalcoholic steatohepatitis (NASH) and end-stage liver disease. Currently, the molecular basis of NASH pathogenesis is poorly understood, and no effective therapies exist to treat NASH. These shortcomings are due to the paucity of experimental NASH models directly relevant to humans.

METHODS

We used chimeric mice with humanized liver to investigate nonalcoholic fatty liver disease in a relevant model. We carried out histologic, biochemical, and molecular approaches including RNA-Seq. For comparison, we used side-by-side human NASH samples.

RESULTS

Herein, we describe a "humanized" model of NASH using transplantation of human hepatocytes into fumarylacetoacetate hydrolase-deficient mice. Once fed a high-fat diet, these mice develop NAFLD faithfully, recapitulating human NASH at the histologic, cellular, biochemical, and molecular levels. Our RNA-Seq analyses uncovered that a variety of important signaling pathways that govern liver homeostasis are profoundly deregulated in both humanized and human NASH livers. Notably, we made the novel discovery that hepatocyte growth factor (HGF) function is compromised in human and humanized NASH at several levels including a significant increase in the expression of the HGF antagonists known as NK1/NK2 and marked decrease in HGF activator. Based on these observations, we generated a potent, human-specific, and stable agonist of human MET that we have named META4 (Metaphor) and used it in the humanized NASH model to restore HGF function.

CONCLUSIONS

Our studies revealed that the humanized NASH model recapitulates human NASH and uncovered that HGF-MET function is impaired in this disease. We show that restoring HGF-MET function by META4 therapy ameliorates NASH and reinstates normal liver function in the humanized NASH model. Our results show that the HGF-MET signaling pathway is a dominant regulator of hepatic homeostasis.

More Pronounced Hypercoagulable State and Hypofibrinolysis in Patients With Cirrhosis With Versus Without HCC

In patients with cirrhosis, particularly those with hepatocellular carcinoma (HCC), hypercoagulability may be associated with purported increased risks of portal vein thrombosis and cirrhosis progression. In this study, we extensively investigated hemostatic alterations potentially responsible for the thrombotic tendency in HCC, and evaluated whether such alterations were predictive of hepatic decompensation. Patients with cirrhosis at all stages were prospectively recruited and underwent an extensive hemostatic assessment, including all procoagulant factors and inhibitors, thrombin generation with and without thrombomodulin (TG), profibrinolytic and antifibrinolytic factors, and plasmin‐antiplasmin complex. In study part 1 (case control), we compared alterations of coagulation and fibrinolysis in patients with cirrhosis with versus without HCC. In study part 2 (prospective), the subgroup of patients with decompensated cirrhosis was followed for development of further decompensation, and predictors of outcome were assessed by multivariate analysis. One‐hundred patients were recruited (50 each with and without HCC). Severity of cirrhosis was comparable between groups. Median HCC volume was 9 cm³ (range: 5‐16). Compared with controls, patients with HCC demonstrated a significantly more prothrombotic hemostatic profile due to increased TG and reduced activation of fibrinolysis, independent of cirrhosis stage. During a median follow‐up of 175 days, 20 patients with decompensated cirrhosis developed further episodes of decompensation that were predicted by low FVII and high plasminogen activator inhibitor‐1 levels, independent of Model for End‐Stage Liver Disease score. Conclusion: Patients with cirrhosis with HCC have profound hyper‐coagulable changes that can account for their increased thrombotic tendency. In contrast, hypercoagulability in patients with decompensated cirrhosis is more likely a consequence of chronic liver disease rather than a driver for cirrhosis progression.

Plasminogen activator inhibitor-1 reduces cardiac fibrosis and promotes M2 macrophage polarization in inflammatory cardiomyopathy

Plasminogen activator inhibitor-1 (PAI-1) has a cardioprotective function in mice by repressing cardiac fibrosis through TGF-β and plasminogen-mediated pathways. In addition it is known to be involved in the recruitment and polarization of monocytes/macrophages towards a M2 phenotype in cancer. Here, we investigated the expression of PAI-1 in human dilated cardiomyopathy (DCM) and inflammatory dilated cardiomyopathy (DCMi) and its effect on cardiac fibrosis and macrophage polarization. We retrospectively analyzed endomyocardial biopsies (EMBs) of patients with DCM or DCMi for PAI-1 expression by immunohistochemistry. Furthermore, EMBs were evaluated for the content of fibrotic tissue, number of activated myofibroblasts, TGF-β expression, as well as for M1 and M2 macrophages. Patients with high-grade DCMi (DCMi-high, CD3⁺ lymphocytes > 30 cells/mm²) had significantly increased PAI-1 levels compared to DCM and low-grade DCMi patients (DCMi-low, CD3⁺ lymphocytes = 14-30 cells/mm²) (15.5 ± 0.4% vs. 1.0 ± 0.1% and 4.0 ± 0.1%, p ≤ 0.001). Elevated PAI-1 expression in DCMi-high subjects was associated with a diminished degree of cardiac fibrosis, decreased levels of TGF-β and reduced number of myofibroblasts. In addition, DCMi-high patients revealed an increased proportion of non-classical M2 macrophages towards classical M1 macrophages, indicating M2 macrophage-favoring properties of PAI-1 in inflammatory cardiomyopathies. Our findings give evidence that elevated expression of cardiac PAI-1 in subjects with high-grade DCMi suppresses fibrosis by inhibiting TGF-β and myofibroblast activation. Moreover, our data indicate that PAI-1 is involved in the polarization of M2 macrophages in the heart. Thus, PAI-1 could serve as a potential prognostic biomarker and as a possible therapeutic target in inflammatory cardiomyopathies.

Plasminogen Activator Inhibitor-1 and Oncogenesis in the Liver Disease

Hepatocellular carcinoma (HCC) is a significant cause of cancer mortality worldwide. Chronic hepatic inflammation and fibrosis play a critical role in the development of HCC. Liver fibrosis develops as a result of response to injury such that a persistent and excessive wound healing response induces extracellular matrix (ECM) deposition leading to HCC. PAI-1 is a fibrinolysis inhibitor involved in regulating protein degradation and homeostasis while assisting wound healing. PAI-1 presents increased levels in various diseases such as fibrosis, cancer, obesity and metabolic syndrome. Moreover, PAI-1 has been extensively studied for developing potential therapies against fibrosis. In the present review, we summarize how PAI-1 affects oncogenesis during liver disease progression based on the recently published literatures. Although there are controversies regarding the role of PAI-1 and approaches to treatment, this review suggests that proper manipulation of PAI-1 activity could provide a novel therapeutic option on the development of chronic liver disease via modulation of cancer stem-like cells (CSCs) differentiation.

PAI-1 augments mucosal damage in colitis

There is a major unmet clinical need to identify pathways in inflammatory bowel disease (IBD) to classify patient disease activity, stratify patients that will benefit from targeted therapies such as anti-tumor necrosis factor (TNF), and identify new therapeutic targets. In this study, we conducted global transcriptome analysis to identify IBD-related pathways using colon biopsies, which highlighted the coagulation gene pathway as one of the most enriched gene sets in patients with IBD. Using this gene-network analysis across 14 independent cohorts and 1800 intestinal biopsies, we found that, among the coagulation pathway genes, plasminogen activator inhibitor-1 (PAI-1) expression was highly enriched in active disease and in patients with IBD who did not respond to anti-TNF biologic therapy and that PAI-1 is a key link between the epithelium and inflammation. Functionally, PAI-1 and its direct target, the fibrinolytic protease tissue plasminogen activator (tPA), played an important role in regulating intestinal inflammation. Intestinal epithelial cells produced tPA, which was protective against chemical and mechanical-mediated colonic injury in mice. In contrast, PAI-1 exacerbated mucosal damage by blocking tPA-mediated cleavage and activation of anti-inflammatory TGF-β, whereas the inhibition of PAI-1 reduced both mucosal damage and inflammation. This study identifies an immune-coagulation gene axis in IBD where elevated PAI-1 may contribute to more aggressive disease.

Stem cell paracrine actions in tissue regeneration and potential therapeutic effect in human endometrium: a retrospective study

OBJECTIVE

Determining genetic and paracrine mechanisms behind endometrial regeneration in Asherman's syndrome and endometrial atrophy (AS/EA) patients after autologous CD133⁺ bone marrow-derived stem cell (CD133⁺ BMDSC) transplantation.

DESIGN

Retrospective study using human endometrial biopsies and mouse models.

SETTING

Fundación-IVI, IIS-La Fe, Valencia, Spain.

SAMPLES

Endometrial biopsies collected before and after CD133⁺ BMDSC therapy, from eight women with AS/EA (NCT02144987) from the uterus of five mice with only left horns receiving CD133⁺ BMDSC therapy.

METHODS

In human samples, haematoxylin and eosin (H&E) staining, RNA arrays, PCR validation, and neutrophil elastase (NE) immunohistochemistry (IHQ). In mouse samples, PCR validation and protein immunoarrays.

MAIN OUTCOME MEASURES

H&E microscopic evaluation, RNA expression levels, PCR, and growth/angiogenic factors quantification, NE IHQ signal.

RESULTS

Treatment improved endometrial morphology and thickness for all patients. In human samples, Jun, Serpine1, and Il4 were up-regulated whereas Ccnd1 and Cxcl8 were down-regulated after treatment. The significant decrease of NE signal corroborated Cxcl8 expression. Animal model analysis confirmed human results and revealed a higher expression of pro-angiogenic cytokines (IL18, HGF, MCP-1, MIP2) in treated uterine horns.

CONCLUSIONS

CD133⁺ BMDSC seems to activate several factors through a paracrine mechanism to help tissue regeneration, modifying endometrial behaviour through an immunomodulatory milieu that precedes proliferation and angiogenic processes. Insight into these processes could bring us one step closer to a non-invasive treatment for AS/EA patients.

TWEETABLE ABSTRACT

CD133⁺ BMDSC therapy regenerates endometrium, modifying the immunological milieu that precedes proliferation and angiogenesis.

A Noncanonical Role for Plasminogen Activator Inhibitor Type 1 in Obesity-Induced Diabetes

Obesity is a major risk factor for type 2 diabetes because of chronic hepatic inflammation and resultant insulin resistance. Hepatocyte growth factor (HGF) is responsible for resetting hepatic homeostasis after injury following activation by urokinase-type plasminogen activator (u-PA; encoded by the PLAU gene). Plasminogen activator inhibitor type-1 (PAI-1; encoded by the SERPINE1 gene), a u-PA inhibitor and antifibrinolytic agent, is often elevated in obesity and is linked to cardiovascular events. We hypothesized that, in addition to its role in preventing fibrinolysis, elevated PAI-1 inhibits HGF's activation by u-PA and the resultant anti-inflammatory and hepatoprotective properties. Wild-type and PAI-1 knockout (KO) mice on a high-fat diet both became significantly heavier than lean controls; however, the obese KO mice demonstrated improved glucose metabolism compared with wild-type mice. Obese KO mice also exhibited an increase in conversion of latent single-chain HGF to active two-chain HGF, coinciding with an increase in the phosphorylation of the HGF receptor (HGFR or MET, encoded by the MET gene), as well as dampened inflammation. These results strongly suggest that, in addition to its other functions, PAI-mediated inhibition of HGF activation prohibits the resolution of inflammation in the context of obesity-induced type 2 diabetes.

Transitional Remodeling of the Hepatic Extracellular Matrix in Alcohol-Induced Liver Injury

Alcohol consumption is a common custom worldwide, and the toxic effects of alcohol on several target organs are well understood. The liver is the primary site of alcohol metabolism and is therefore the major target of alcohol toxicity. Alcoholic liver disease is a spectrum of disease states, ranging from simple steatosis (fat accumulation), to inflammation, and eventually to fibrosis and cirrhosis if untreated. The fibrotic stage of ALD is primarily characterized by robust accumulation of extracellular matrix (ECM) proteins (collagens) which ultimately impairs the function of the organ. The role of the ECM in early stages of ALD is poorly understood, but recent research has demonstrated that a number of changes in the hepatic ECM in prefibrotic ALD not only are present, but may also contribute to disease progression. The purpose of this review is to summarize the established and proposed changes to the hepatic extracellular matrix (ECM) that may contribute to earlier stages of ALD development and to discuss potential mechanisms by which these changes may mediate the progression of the disease.

Metabolic derivatives of alcohol and the molecular culprits of fibro-hepatocarcinogenesis: Allies or enemies?

Chronic intake of alcohol undoubtedly overwhelms the structural and functional capacity of the liver by initiating complex pathological events characterized by steatosis, steatohepatitis, hepatic fibrosis and cirrhosis. Subsequently, these initial pathological events are sustained and ushered into a more complex and progressive liver disease, increasing the risk of fibro-hepatocarcinogenesis. These coordinated pathological events mainly result from buildup of toxic metabolic derivatives of alcohol including but not limited to acetaldehyde (AA), malondialdehyde (MDA), CYP2E1-generated reactive oxygen species, alcohol-induced gut-derived lipopolysaccharide, AA/MDA protein and DNA adducts. The metabolic derivatives of alcohol together with other comorbidity factors, including hepatitis B and C viral infections, dysregulated iron metabolism, abuse of antibiotics, schistosomiasis, toxic drug metabolites, autoimmune disease and other non-specific factors, have been shown to underlie liver diseases. In view of the multiple etiology of liver diseases, attempts to delineate the mechanism by which each etiological factor causes liver disease has always proved cumbersome if not impossible. In the case of alcoholic liver disease (ALD), it is even more cumbersome and complicated as a result of the many toxic metabolic derivatives of alcohol with their varying liver-specific toxicities. In spite of all these hurdles, researchers and experts in hepatology have strived to expand knowledge and scientific discourse, particularly on ALD and its associated complications through the medium of scientific research, reviews and commentaries. Nonetheless, the molecular mechanisms underpinning ALD, particularly those underlying toxic effects of metabolic derivatives of alcohol on parenchymal and non-parenchymal hepatic cells leading to increased risk of alcohol-induced fibro-hepatocarcinogenesis, are still incompletely elucidated. In this review, we examined published scientific findings on how alcohol and its metabolic derivatives mount cellular attack on each hepatic cell and the underlying molecular mechanisms leading to disruption of core hepatic homeostatic functions which probably set the stage for the initiation and progression of ALD to fibro-hepatocarcinogenesis. We also brought to sharp focus, the complex and integrative role of transforming growth factor beta/small mothers against decapentaplegic/plasminogen activator inhibitor-1 and the mitogen activated protein kinase signaling nexus as well as their cross-signaling with toll-like receptor-mediated gut-dependent signaling pathways implicated in ALD and fibro-hepatocarcinogenesis. Looking into the future, it is hoped that these deliberations may stimulate new research directions on this topic and shape not only therapeutic approaches but also models for studying ALD and fibro-hepatocarcinogenesis.

Attrition of Hepatic Damage Inflicted by Angiotensin II with α-Tocopherol and β-Carotene in Experimental Apolipoprotein E Knock-out Mice

Angiotensin II is one of the key regulatory peptides implicated in the pathogenesis of liver disease. The mechanisms underlying the salubrious role of α-tocopherol and β-carotene on liver pathology have not been comprehensively assessed. Here, we investigated the mechanisms underlying the role of Angiotensin II on hepatic damage and if α-tocopherol and β-carotene supplementation attenuates hepatic damage. Hepatic damage was induced in Apoe(-/-)mice by infusion of Angiotensin II followed by oral administration with α-tocopherol and β-carotene-enriched diet for 60 days. Investigations showed fibrosis, kupffer cell hyperplasia, hepatocyte degeneration and hepatic cell apoptosis; sinusoidal dilatation along with haemorrhages; evidence of fluid accumulation; increased ROS level and increased AST and ALT activities. In addition, tPA and uPA were down-regulated due to 42-fold up-regulation of PAI-1. MMP-2, MMP-9, MMP-12, and M-CSF were down-regulated in Angiotensin II-treated animals. Notably, α-tocopherol and β-carotene treatment controlled ROS, fibrosis, hepatocyte degeneration, kupffer cell hyperplasia, hepatocyte apoptosis, sinusoidal dilatation and fluid accumulation in the liver sinusoids, and liver enzyme levels. In addition, PAI-1, tPA and uPA expressions were markedly controlled by β-carotene treatment. Thus, Angiotensin II markedly influenced hepatic damage possibly by restraining fibrinolytic system. We concluded that α-tocopherol and β-carotene treatment has salubrious role in repairing hepatic pathology.

Fibrinolysis and the control of blood coagulation

Fibrin plays an essential role in hemostasis as both the primary product of the coagulation cascade and the ultimate substrate for fibrinolysis. Fibrinolysis efficiency is greatly influenced by clot structure, fibrinogen isoforms and polymorphisms, the rate of thrombin generation, the reactivity of thrombus-associated cells such as platelets, and the overall biochemical environment. Regulation of the fibrinolytic system, like that of the coagulation cascade, is accomplished by a wide array of cofactors, receptors, and inhibitors. Fibrinolytic activity can be generated either on the surface of a fibrin-containing thrombus, or on cells that express profibrinolytic receptors. In a widening spectrum of clinical disorders, acquired and congenital defects in fibrinolysis contribute to disease morbidity, and new assays of global fibrinolysis now have potential predictive value in multiple clinical settings. Here, we summarize the basic elements of the fibrinolytic system, points of interaction with the coagulation pathway, and some recent clinical advances.

Oral intake of chicoric acid reduces acute alcohol-induced hepatic steatosis in mice

OBJECTIVE

Acute and chronic consumption of alcohol can alter intestinal barrier function thereby increasing portal endotoxin levels subsequently leading to an activation of toll-like receptor (TLR) 4-dependent signaling cascades, elevated levels of reactive oxygen species and induction of tumor necrosis factor α in the liver. Recent studies suggest that chicoric acid found in Echinacea pupurea, chicory, and other plants, may possess antioxidant and anti-inflammatory effects. The aim of the present study was to determine if chicoric acid can reduce acute alcohol-induced liver damage.

METHODS

Female mice were given chicoric acid orally (4 mg/kg body weight) for 4 d before acute ethanol administration (6 g/kg body weight). Furthermore, the effect of chicoric acid on the lipopolysaccharide (LPS)-dependent activation in an in vitro model of Kupffer cells (RAW264.7 macrophages) was assessed.

RESULTS

Acute alcohol ingestion caused a significant increase in hepatic triacylglycerols accumulation, which was associated with increased protein levels of the inducible nitric oxide synthase (iNOS), 4-hydroxynonenal protein adducts, and active plasminogen activator inhibitor 1 protein in the liver. Pretreatment of animals with chicoric acid significantly attenuated these effects of alcohol on the liver. In LPS-treated RAW264.7 macrophages, pretreatment with chicoric acid significantly suppressed LPS-induced mRNA expression of iNOS and tumor necrosis factor α.

CONCLUSION

These data suggest that chicoric acid may reduce acute alcohol-induced steatosis in mice through interfering with the induction of iNOS and iNOS-dependent signaling cascades in the liver.

Cellular and molecular mechanisms in the pathogenesis of liver fibrosis: An update

There have been considerable recent advances towards a better understanding of the complex cellular and molecular network underlying liver fibrogenesis. Recent data indicate that the termination of fibrogenic processes and the restoration of deficient fibrolytic pathways may allow the reversal of advanced fibrosis and even cirrhosis. Therefore, efforts have been made to better clarify the cellular and molecular mechanisms that are involved in liver fibrosis. Activation of hepatic stellate cells (HSCs) remains a central event in fibrosis, complemented by other sources of matrix-producing cells, including portal fibroblasts, fibrocytes and bone marrow-derived myofibroblasts. These cells converge in a complex interaction with neighboring cells to provoke scarring in response to persistent injury. Defining the interaction of different cell types, revealing the effects of cytokines on these cells and characterizing the regulatory mechanisms that control gene expression in activated HSCs will enable the discovery of new therapeutic targets. Moreover, the characterization of different pathways associated with different etiologies aid in the development of disease-specific therapies. This article outlines recent advances regarding the cellular and molecular mechanisms involved in liver fibrosis that may be translated into future therapies. The pathogenesis of liver fibrosis associated with alcoholic liver disease, non-alcoholic fatty liver disease and viral hepatitis are also discussed to emphasize the various mechanisms involved in liver fibrosis.

Kupffer cells in the liver

Kupffer cells are a critical component of the mononuclear phagocytic system and are central to both the hepatic and systemic response to pathogens. Kupffer cells are reemerging as critical mediators of both liver injury and repair. Kupffer cells exhibit a tremendous plasticity; depending on the local metabolic and immune environment, then can express a range of polarized phenotypes, from the proinflammatory M1 phenotype to the alternative/M2 phenotype. Multiple M2 phenotypes can be distinguished, each involved in the resolution of inflammation and wound healing. Here, we have provided an update on recent research that has contributed to the developing delineation of the contribution of Kupffer cells to different types of liver injury, with an emphasis on alcoholic and nonalcoholic liver diseases. These recent advances in our understanding of Kupffer cell function and regulation will likely provide new insights into the potential for therapeutic manipulation of Kupffer cells to promote the resolution of inflammation and enhance wound healing in liver disease.

Expression of deleted in liver cancer 1 and plasminogen activator inhibitor 1 protein in ovarian carcinoma and their clinical significance

Background

The deleted in liver cancer 1 (DLC1) and plasminogen activator inhibitor 1 (PAI-1) are known to be closely associated with tumor growth and metastasis in several kinds of human tumors. The aim of this study was to investigate the expression of DLC1 and PAI-1 in ovarian carcinoma, and evaluate their relations with the prognosis of ovarian carcinoma.

Methods

Immunohistochemical staining and Western blot were used to examine the expressions of DLC1 and PAI-1 protein in 25 specimens normal ovarian tissues, 52 specimens of serous cystadenocarcinoma tissues and 23 specimens of mucinous cystadenocarcinoma tissues. Chi-square test, Logistic regression and Partial Correlate analysis were performed to evaluate the association between DLC1 and PAI-1 with clinicopathological characteristics. Overall survival was estimated by Kaplan-Meier curves and multivariate Cox analysis. The relationships between DLC1 and PAI-1 protein expression were analyzed by Pearson’s correlation coefficient.

Results

The expression of DLC1 protein in ovarian carcinoma tissues was significantly lower than that in normal ovarian tissues, but it was converse for PAI-1. In ovarian carcinoma, the expression of DLC1 was significantly associated with advanced FIGO stage, ascites and positive lymph node metastasis, whereas PAI-1 protein was closely related with advanced FIGO stage, poor histological differentiation and lymph node metastasis. The expression of DLC1 was negatively correlated with PAI-1 in ovarian carcinoma. Ovarian cancer patients with negative expression of DLC1 and positive expression of PAI-1 had the worst overall survival time compared to other patients.

Conclusions

The expression of DLC1 and PAI-1 were closely related with the metastasis and invasion of ovarian carcinoma, only the combination of DLC1 and PAI-1 could serve as an independent prognostic factor of ovarian carcinoma.

Association of hepatitis C with markers of hemostasis in HIV-infected and uninfected women in the women's interagency HIV study (WIHS)

BACKGROUND

Coinfection with HIV and hepatitis C virus (HCV) is common. HIV infection and treatment are associated with hypercoagulability; thrombosis in HCV is underinvestigated. Proposed markers of hemostasis in HIV include higher D-dimer, Factor VIII%, and plasminogen activator inhibitor-1 (PAI-1) antigen and lower total Protein S% (TPS) but have not been examined in HCV. We assessed the independent association of HCV with these 4 measures of hemostasis in a multicenter, prospective study of HIV: the Women's Interagency HIV Study.

METHODS

We randomly selected 450 HCV-infected (anti-HCV+ with detectable plasma HCV RNA) and 450 HCV-uninfected (anti-HCV-) women. HCV was the main exposure of interest in regression models.

RESULTS

Four hundred forty-three HCV+ and 425 HCV- women were included. HCV+ women had higher Factor VIII% (124.4% ± 3.9% vs. 101.8% ± 3.7%, P < 0.001) and lower TPS (75.7% ± 1.1% vs. 84.3% ± 1.1%, <0.001) than HCV- women, independent of HIV infection and viral load; there was little difference in PAI-1 or log10 D-dimer. After adjustment for confounders, these inferences remained. HIV infection was independently associated with higher Factor VIII% and log10 D-dimer and lower TPS.

CONCLUSIONS

HCV was independently associated with higher Factor VIII% and lower TPS consistent with hypercoagulability. Higher Factor VIII% and D-dimer and lower TPS were also strongly associated with HIV infection and levels of HIV viremia, independent of HCV infection. Further investigation is needed to determine if there is increased thrombotic risk from HCV. Studies examining hemostasis markers in HIV infection must also assess the contribution of HCV infection.

Bermuda Triangle for the liver: alcohol, obesity, and viral hepatitis

Despite major progress in understanding and managing liver disease in the past 30 years, it is now among the top 10 most common causes of death globally. Several risk factors, such as genetics, diabetes, obesity, excessive alcohol consumption, viral infection, gender, immune dysfunction, and medications, acting individually or in concert, are known to precipitate liver damage. Viral hepatitis, excessive alcohol consumption, and obesity are the major factors causing liver injury. Estimated numbers of hepatitis B virus (HBV) and hepatitis C virus (HCV)-infected subjects worldwide are staggering (370 and 175 million, respectively), and of the 40 million known human immunodeficiency virus positive subjects, 4 and 5 million are coinfected with HBV and HCV, respectively. Alcohol and HCV are the leading causes of end-stage liver disease worldwide and the most common indication for liver transplantation in the United States and Europe. In addition, the global obesity epidemic that affects up to 40 million Americans, and 396 million worldwide, is accompanied by an alarming incidence of end-stage liver disease, a condition exacerbated by alcohol. This article focuses on the interactions between alcohol, viral hepatitis, and obesity (euphemistically described here as the Bermuda Triangle of liver disease), and discusses common mechanisms and synergy.

Role of matrix metalloproteinases and tissue inhibitor of metalloproteinases type-1 in the development of alcoholic liver fibrosis in rats

AIM: To study the role of matrix metalloproteinases and tissue inhibitor of metalloproteinases type-1 in alcoholic liver fibrosis (ALF) in rats by dynamically monitoring their expression in ALF.

METHODS: SD rats were randomly divided into three groups: a control group, a CCl₄ group and an experimental group. The experiment group was intragastrically given a mixture (560 mL/L alcohol, 10 mL/kg; corn oil 2 mL/kg; pyrazole 25 mg/kg) once a day and an intraperitoneal injection of 0.3 mL/kg 25% CCl4 solution (in olive oil) twice a week. The CCl₄ group received an intraperitoneal injection of CCl₄ solution and was intragastrically given equal volume of normal saline (12 mL/kg per day). The control group was given equal volume of normal saline both intraperitoneally and intragastrically. The rats were anaesthetized and killed 4, 8, 10 and 12 wk after modeling. Serum levels of ALT and AST were measured. Pathological changes in liver tissues were observed. The expression of MMP2, MMP9 and TIMP-1 was detected by Western blot and real-time PCR.

RESULTS: Compared to the control group, the CCl₄ group showed no significant changes in body weight, liver weight, liver/body weight ratio and serum transaminase levels, but the experimental group had significantly decreased body weight and significantly increased liver weight, liver/body weight ratio and serum transaminases. In the experimental group, with the increase in the severity of liver fibrosis, MMP2, MMP9 and TIMP-1 levels were gradually elevated, and expression of TIMP-1 increased more obviously than that of MMP2 and MMP9.

CONCLUSION: MMP2, MMP9 and TIMP-1 may play an important role in the pathogenesis of ALF in rats.

Transforming growth factor β neutralization ameliorates pre-existing hepatic fibrosis and reduces cholangiocarcinoma in thioacetamide-treated rats

Considerable evidence has demonstrated that transforming growth factor β (TGF-β) plays a key role in hepatic fibrosis, the final common pathway for a variety of chronic liver diseases leading to liver insufficiency. Although a few studies have reported that blocking TGF-β with soluble receptors or siRNA can prevent the progression of hepatic fibrosis, as yet no evidence has been provided that TGF-β antagonism can improve pre-existing hepatic fibrosis. The aim of this study was to examine the effects of a murine neutralizing TGF-β monoclonal antibody (1D11), in a rat model of thioacetamide (TAA)-induced hepatic fibrosis. TAA administration for 8 weeks induced extensive hepatic fibrosis, whereupon 1D11 dosing was initiated and maintained for 8 additional weeks. Comparing the extent of fibrosis at two time points, pre- and post-1D11 dosing, we observed a profound regression of tissue injury and fibrosis upon treatment, as reflected by a reduction of collagen deposition to a level significantly less than that observed before 1D11 dosing. Hepatic TGF-β1 mRNA, tissue hydroxyproline, and plasminogen activator inhibitor 1 (PAI-1) levels were significantly elevated at the end of the 8 week TAA treatment. Vehicle and antibody control groups demonstrated progressive injury through 16 weeks, whereas those animals treated for 8 weeks with 1D11 showed striking improvement in histologic and molecular endpoints. During the course of tissue injury, TAA also induced cholangiocarcinomas. At the end of study, the number and area of cholangiocarcinomas were significantly diminished in rats receiving 1D11 as compared to control groups, presumably by the marked reduction of supporting fibrosis/stroma. The present study demonstrates that 1D11 can reverse pre-existing hepatic fibrosis induced by extended dosing of TAA. The regression of fibrosis was accompanied by a marked reduction in concomitantly developed cholangiocarcinomas. These data provide evidence that therapeutic dosing of a TGF-β antagonist can diminish and potentially reverse hepatic fibrosis and also reduce the number and size of attendant cholangiocarcinomas.

Interferon-gamma-mediated tissue factor expression contributes to T-cell-mediated hepatitis through induction of hypercoagulation in mice

Concanavalin A (Con A) treatment induces severe hepatitis in mice in a manner dependent on T cells, interferon (IFN)-gamma, and tumor necrosis factor (TNF). Treatment with the anticoagulant heparin protects against hepatitis, despite healthy production of IFN-γ and TNF. Here, we investigated molecular and cellular mechanisms for hypercoagulation-mediated hepatitis. After Con A challenge, liver of wild-type (WT) mice showed prompt induction of Ifnγ and Tnf, followed by messenger RNA expression of tissue factor (TF) and plasminogen activator inhibitor-1 (PAI-1), which initiate blood coagulation and inhibit clot lysis, respectively. Mice developed dense intrahepatic fibrin deposition and massive liver necrosis. In contrast, Ifnγ(-/-) mice and Ifnγ(-/-) Tnf(-/-) mice neither induced Pai1 or Tf nor developed hepatitis. In WT mice TF blockade with an anti-TF monoclonal antibody protected against Con A-induced hepatitis, whereas Pai1(-/-) mice were not protected. Both hepatic macrophages and sinusoidal endothelial cells (ECs) expressed Tf after Con A challenge. Macrophage-depleted WT mice reconstituted with hematopoietic cells, including macrophages deficient in signal transducer and activator of transcription-1 (STAT1) essential for IFN-γ signaling, exhibited substantial reduction of hepatic Tf and of liver injuries. This was also true for macrophage-depleted Stat1(-/-) mice reconstituted with WT macrophages. Exogenous IFN-γ and TNF rendered T-cell-null, Con A-resistant mice deficient in recombination-activating gene 2, highly susceptible to Con A-induced liver injury involving TF.

CONCLUSIONS

Collectively, these results strongly suggest that proinflammatory signals elicited by IFN-γ, TNF, and Con A in both hepatic macrophages and sinusoidal ECs are necessary and sufficient for the development of hypercoagulation-mediated hepatitis.

Correlates and reference limits of plasma gamma-glutamyltransferase fractions from the Framingham Heart Study

BACKGROUND

We assessed GGT fractions correlates and their reference values in the Offspring Cohort of the Framingham Heart Study.

METHODS

Correlates of GGT fractions were assessed by multivariable regression analysis in 3203 individuals [47% men, mean age (SD): 59 (10) years]. GGT fractions reference values were established by empirical quantile analysis in a reference group of 432 healthy subjects [45% men, 57 (10) years].

RESULTS

Fractional GGT levels were higher in men than in women (P<0.0001). In both sexes, fractions were associated with: triglycerides were associated with b-GGT, alcohol consumption with m-, s- and f-GGT. C-reactive protein with m- and s-GGT, while plasminogen activator inhibitor-1 with b- and f-GGT. Body mass index, blood pressure, glucose and triglycerides correlated with b- and f-GGT. In comparison with the reference group [b-GGT/s-GGT median (Q1-Q3): 0.51 (0.35-0.79)U/L], subjects affected by cardiovascular disease or diabetes showed no change of b/s ratio [0.52 (0.34-0.79)U/L, 0.57 (0.40-0.83)U/L, respectively]. The b/s ratio was higher in presence of metabolic syndrome [0.61 (0.42-0.87)U/L, P<0.0001], while lower in heavy alcohol consumers [0.41 (0.28-0.64)U/L, P<0.0001].

CONCLUSIONS

Metabolic and cardiovascular risk markers are important correlates of GGT fractions, in particular of b-GGT.

Does fructose consumption contribute to non-alcoholic fatty liver disease?

Fructose is mainly consumed with added sugars (sucrose and high fructose corn syrup), and represents up to 10% of total energy intake in the US and in several European countries. This hexose is essentially metabolized in splanchnic tissues, where it is converted into glucose, glycogen, lactate, and, to a minor extent, fatty acids. In animal models, high fructose diets cause the development of obesity, insulin resistance, diabetes mellitus, and dyslipidemia. Ectopic lipid deposition in the liver is an early occurrence upon fructose exposure, and is tightly linked to hepatic insulin resistance. In humans, there is strong evidence, based on several intervention trials, that fructose overfeeding increases fasting and postprandial plasma triglyceride concentrations, which are related to stimulation of hepatic de novo lipogenesis and VLDL-TG secretion, together with decreased VLDL-TG clearance. However, in contrast to animal models, fructose intakes as high as 200 g/day in humans only modestly decreases hepatic insulin sensitivity, and has no effect on no whole body (muscle) insulin sensitivity. A possible explanation may be that insulin resistance and dysglycemia develop mostly in presence of sustained fructose exposures associated with changes in body composition. Such effects are observed with high daily fructose intakes, and there is no solid evidence that fructose, when consumed in moderate amounts, has deleterious effects. There is only limited information regarding the effects of fructose on intrahepatic lipid concentrations. In animal models, high fructose diets clearly stimulate hepatic de novo lipogenesis and cause hepatic steatosis. In addition, some observations suggest that fructose may trigger hepatic inflammation and stimulate the development of hepatic fibrosis. This raises the possibility that fructose may promote the progression of non-alcoholic fatty liver disease to its more severe forms, i.e. non-alcoholic steatohepatitis and cirrhosis. In humans, a short-term fructose overfeeding stimulates de novo lipogenesis and significantly increases intrahepatic fat concentration, without however reaching the proportion encountered in non-alcoholic fatty liver diseases. Whether consumption of lower amounts of fructose over prolonged periods may contribute to the pathogenesis of NAFLD has not been convincingly documented in epidemiological studies and remains to be further assessed.

Proteomic analysis of extracellular matrix from the hepatic stellate cell line LX-2 identifies CYR61 and Wnt-5a as novel constituents of fibrotic liver

Activation of hepatic stellate cells (HSCs) and subsequent uncontrolled accumulation of altered extracellular matrix (ECM) underpin liver fibrosis, a wound healing response to chronic injury, which can lead to organ failure and death. We sought to catalogue the components of fibrotic liver ECM to obtain insights into disease etiology and aid identification of new biomarkers. Cell-derived ECM was isolated from the HSC line LX-2, an in vitro model of liver fibrosis, and compared to ECM from human foreskin fibroblasts (HFFs) as a control. Mass spectrometry analyses of cell-derived ECMs identified, with ≥99% confidence, 61 structural ECM or secreted proteins (48 and 31 proteins for LX-2 and HFF, respectively). Gene ontology enrichment analysis confirmed the enrichment of ECM proteins, and hierarchical clustering coupled with protein–protein interaction network analysis revealed a subset of proteins enriched to fibrotic ECM, highlighting the existence of cell type-specific ECM niches. Thirty-six proteins were enriched to LX-2 ECM as compared to HFF ECM, of which Wnt-5a and CYR61 were validated by immunohistochemistry in human and murine fibrotic liver tissue. Future studies will determine if these and other components may play a role in the etiology of hepatic fibrosis, serve as novel disease biomarkers, or open up new avenues for drug discovery.

Acute alcohol-induced liver injury

Alcohol consumption is customary in most cultures and alcohol abuse is common worldwide. For example, more than 50% of Americans consume alcohol, with an estimated 23.1% of Americans participating in heavy and/or binge drinking at least once a month. A safe and effective therapy for alcoholic liver disease (ALD) in humans is still elusive, despite significant advances in our understanding of how the disease is initiated and progresses. It is now clear that acute alcohol binges not only can be acutely toxic to the liver, but also can contribute to the chronicity of ALD. Potential mechanisms by which acute alcohol causes damage include steatosis, dysregulated immunity and inflammation, and altered gut permeability. Recent interest in modeling acute alcohol exposure has yielded new insights into potential mechanisms of acute injury, which also may well be relevant for chronic ALD. Recent work by this group on the role of PAI-1 and fibrin metabolism in mediating acute alcohol-induced liver damage serve as an example of possible new targets that may be useful for alcohol abuse, be it acute or chronic.

Serum cytokeratin 18 and cytokine elevations suggest a high prevalence of occupational liver disease in highly exposed elastomer/polymer workers

OBJECTIVE

Cytokeratin 18 (CK18) is a novel serologic biomarker for occupational liver disease. The purpose of this study is to determine the prevalence of CK18 elevation in elastomer/polymer workers exposed to acrylonitrile, 1,3-butadiene, and styrene.

METHODS

A total of 82 chemical workers were evaluated. Cytokeratin 18 was determined by enzyme-linked immunosorbent assay and proinflammatory cytokines were measured by multi-analyte chemiluminescent detection.

RESULTS

Thirty-nine percent (32 of 82) had elevated CK18 levels, which were not explained by alcohol or obesity, except in potentially four cases. The pattern of CK18 elevation was consistent with toxicant-associated steatohepatitis (TASH) in the majority of cases (78%). Tumor necrosis factor α, interleukin-6, interleukin-8, monocyte chemotactic protein-1, and plasminogen activator inhibitor-1 were increased in these workers compared with those with normal CK18 levels.

CONCLUSIONS

These results suggest a high prevalence of occupational liver disease and TASH in elastomer/polymer workers with elevated proinflammatory cytokines.

Effects of pharmacological suppression of plasminogen activator inhibitor-1 in myocardial remodeling after ischemia reperfusion injury

Plasminogen activator inhibitor-1 (PAI-1) contributes to cardiac ventricular remodeling because migration of inflammatory cells and attenuation of extracellular matrix degradation are caused by plasmin and matrix metalloproteinase. However, the roles of PAI-1 in myocardial ischemia reperfusion (I/R) injury and the following inflammatory response have not yet been well elucidated. To clarify the role of PAI-1 in myocardial I/R injury, we used a specific PAI-1 inhibitor (IMD-1622) in a rat model. The left anterior descending coronary artery was ligated and reperfusion was performed by loosening the suture after 30 minutes of arterial occlusion. A single administration of IMD-1622 (20 mg/kg) or vehicle was given intraperitoneally and then the rats were sacrificed on day 1 or day 14 after I/R. Blood pressure, echocardiograms, histopathology, and molecular examination were performed. The examinations revealed that PAI-1 inhibitor showed limited effects on cardiac dysfunction and ventricular remodeling after I/R. We conclude that the pharmacological inhibition of PAI-1 may not affect ventricular remodeling after myocardial I/R injury.

Histone H3 phosphorylation (Ser10, Ser28) and phosphoacetylation (K9S10) are differentially associated with gene expression in liver of rats treated in vivo with acute ethanol

The epigenetic histone modification by ethanol is emerging as one of the mechanisms for its deleterious effects in the liver. In this context, we have investigated the role of histone H3 phosphorylation at Ser10 (P-H3-Ser10), and Ser28 (P-H3-Ser28) in liver after acute ethanol treatment in vivo. Ethanol was administered intraperitoneally in male Sprague-Dawley rats. Ethanol dose-response (1-5 g/kg body weight) and time-course (1-4 h) experiments were conducted, and various parameters were monitored. Steatosis and necrosis (serum alanine aminotransferase) of the liver increased in 4 h, suggesting liver injury. There were differences between P-H3-Ser10 and P-H3-Ser28 at 1 h, with the latter being more sensitive to lower ethanol doses. It was noteworthy that phosphorylation of both serines disappeared at the highest dose used (5 g/kg). We also examined phosphoacetylation of histone H3 at K9S10 and observed a dramatic increase. The changes in histone H3 phosphorylation and phosphoacetylation were also accompanied with expression of early response genes (c-fos, c-jun, mitogen-activated protein kinase phosphatase-1). Chromatin immunoprecipitation assays in samples from 1.5 and 4 h of ethanol administration indicated that increased histone H3 phosphorylation at Ser28 was associated with the promoters of c-jun and plasminogen activator inhibitor-1. In conclusion, this study demonstrates for the first time that in vivo exposure of liver to acute ethanol induced phosphorylation and phosphoacetylation of histone H3, and these modifications are differentially involved in the mRNA expression of genes.

PPAR nuclear receptors and altered RPE lipid metabolism in age-related macular degeneration

The pathophysiology of 'early' dry age-related macular degeneration (ARMD), characterized by the accumulation of lipid and protein-rich sub-retinal deposits remains largely unknown. Accumulation and dysregulated turnover of lipids as well as extracellular matrix (ECM) molecules in sub-retinal pigment epithelial (RPE) deposits and Bruch's membrane, itself an ECM, play a role in ARMD. Epidemiological studies have shown an increased risk for the disease associated with higher dietary intake of long chain poly-unsaturated fatty acids (LCPUFA) and specifically more so for n-6 versus n-3 fatty acids. PUFAs are membrane targets of lipid peroxidation and natural ligands for the nuclear receptors, peroxisome proliferator activated receptors (PPAR). Here we investigated the expression of genes involved in lipid metabolism and expression of the three isoforms of PPARs in an immortalized cell line of human RPE cells (ARPE19) in the presence or absence of fatty acids.

Adipokines and redox signaling: impact on fatty liver disease

Adipokines (adipose tissue cytokines) are polypeptide factors secreted by adipose tissue in a highly regulated manner. The 'classical' adipokines (leptin, adiponectin, and resistin) are expressed only by adipocytes, but other adipokines have been shown to be released by resident and infiltrating macrophages, as well as by components of the vascular stroma. Indeed, adipose tissue inflammation is known to be associated with a modification in the pattern of adipokine secretion. Several studies indicate that adipokines can interfere with hepatic injury associated with fatty infiltration, differentially modulating steatosis, inflammation, and fibrosis. Moreover, plasma levels of adipokines have been investigated in patients with nonalcoholic fatty liver disease in order to establish correlations with the underlying state of insulin resistance and with the type and severity of hepatic damage. In this Forum article, we provide a review of recent data that suggest a significant role for oxidative stress, reactive oxygen species, and redox signaling in mediating actions of adipokines that are relevant in the pathogenesis of nonalcoholic fatty liver disease, including hepatic insulin resistance, inflammation, and fibrosis.

Pathogenesis of alcohol-induced liver disease: classical concepts and recent advances

Alcoholic liver disease (ALD) is a primary consequence of heavy and prolonged drinking. ALD contributes to the bulk of liver disease burden worldwide. Progression of ALD is a multifactorial and multistep process that includes many genetic and environmental risk factors. The molecular pathogenesis of ALD involves alcohol metabolism and secondary mechanisms such as oxidative stress, endotoxin, cytokines and immune regulators. The histopathological manifestation of ALD occurs as an outcome of complex but controlled interactions between hepatic cell types. Hepatic stellate cells (HSCs) are the key drivers of fibrogenesis, but transformation of hepatocytes to myofibroblastoids also implicate parenchymal cells as playing an active role in hepatic fibrogenesis. Recent discoveries indicate that lipogenesis during the early stages of ALD is a risk for advancement to cirrhosis. Other recently identified novel molecules and physiological/cell signaling pathways include fibrinolysis, osteopontin, transforming growth factor-β-SMAD and hedgehog signaling, and involvement of novel cytokines in hepatic fibrogenesis. The observation that ALD and non-alcoholic steatohepatitis share common pathways and genetic polymorphisms suggests operation of parallel pathogenic mechanisms. Future research involving genomics, epigenomics, deep sequencing and non-coding regulatory elements holds promise to identify novel diagnostic and therapeutic targets for ALD. There is also a need for adequate animal models to study pathogenic mechanisms at the molecular level and targeted therapy.

Fructose-induced steatosis in mice: role of plasminogen activator inhibitor-1, microsomal triglyceride transfer protein and NKT cells

Plasminogen activator inhibitor-1 (PAI-1) is an acute-phase protein known to be involved in alcoholic liver disease and hepatic fibrosis. In the present study, the hypothesis that PAI-1 is causally involved in the onset of fructose-induced hepatic steatosis was tested in a mouse model. Wild-type C57BL/6J and PAI-1⁻/⁻ mice were fed with 30% fructose solution or water for 8 weeks. Markers of hepatic steatosis, expression of PAI-1, apolipoprotein B (ApoB), cluster of differentiation 1d (CD1d), markers of natural killer T (NKT) cells, protein levels of phospho-c-Met and tumor necrosis factor-α (TNF-α) were determined. Activity of the microsomal triglyceride transfer protein (MTTP) was measured in liver tissue. In comparison with water controls, chronic intake of 30% fructose solution caused a significant increase in hepatic triglycerides, PAI-1 expression and plasma alanine aminotransferase levels in wild-type mice. This effect of fructose feeding was markedly attenuated in PAI-1⁻/⁻ mice. Despite no differences in portal endotoxin levels and hepatic TNF-α protein levels between fructose-fed groups, the protective effect of the loss of PAI-1 against the onset of fructose-induced steatosis was associated with a significant increase in phospho-c-Met, phospho Akt, expression of ApoB and activity of MTTP in livers of PAI-1⁻/⁻ mice in comparison with fructose-fed wild types. Moreover, in PAI-1⁻/⁻ mice, expressions of CD1d and markers of CD1d-reactive NKT cells were markedly higher than in wild-type mice; however, expression of markers of activation of CD1d-reactive NKT cells (eg, interleukin-15 and interferon-γ) were only found to be increased in livers of fructose-fed PAI-1⁻/⁻ mice. Taken together, these data suggest that PAI-1 has a causal role in mediating the early phase of fructose-induced liver damage in mice through signaling cascades downstream of Kupffer cells and TNF-α.

Advances in alcoholic liver disease

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.

Mechanisms and cell signaling in alcoholic liver disease

Alcoholic liver disease (ALD) remains a major cause of morbidity and mortality worldwide. For example, the Veterans Administration Cooperative Studies reported that patients with cirrhosis and superimposed alcoholic hepatitis had a 4-year mortality of >60%. The poor prognosis of ALD implies that preventing disease progression would be more effective than treating end-stage liver disease. An obvious avenue of prevention would be to remove the damaging agent; however, the infamously high rate of recidivism in alcoholics makes maintaining abstinence a difficult treatment goal to prevent ALD. Indeed, although the progression of ALD is well-characterized, there is no universally accepted therapy available to halt or reverse this process in humans. With better understanding of the mechanism(s) and risk factors that mediate the initiation and progression of ALD, rational targeted therapy can be developed to treat or prevent ALD. The purpose of this review is to summarize the established and proposed mechanisms by which chronic alcohol abuse damages the liver and to highlight key signaling events known or hypothesized to mediate these effects.

Pathogenesis of alcoholic liver disease: the role of nuclear receptors

Ethanol consumption causes fatty liver, which can lead to inflammation, fibrosis, cirrhosis and even liver cancer. The molecular mechanisms by which ethanol exerts its damaging effects are extensively studied, but not fully understood. It is now evident that nuclear receptors (NRs), including retinoid x receptor alpha and peroxisome proliferator-activated receptors, play key roles in the regulation of lipid homeostasis and inflammation during the pathogenesis of alcoholic liver disease (ALD). Given their pivotal roles in physiological processes, NRs represent potential therapeutic targets for the treatment and prevention of numerous metabolic and lipid-related diseases including ALD. This review summarizes the factors that contribute to ALD and the molecular mechanisms of ALD with a focus on the role of NRs.

Uridine triphosphate (UTP) induces profibrotic responses in cardiac fibroblasts by activation of P2Y2 receptors

Cardiac fibroblasts (CFs) play a key role in response to injury and remodeling of the heart. Nucleotide (P2) receptors regulate the heart but limited information is available regarding such receptors in CFs. We thus sought to determine if extracellular nucleotides regulate fibrotic responses (e.g., proliferation, migration and expression of profibrotic markers) of CFs in primary culture. UTP increased rat CF migration 3-fold (p<0.001), proliferation by 30% (p<0.05) and mRNA expression of profibrotic markers: alpha smooth muscle actin (alpha-SMA), plasminogen activator inhibitor-1 (PAI-1), transforming growth factor beta, soluble ST2, interleukin-6 and monocyte chemoattractant protein-1 (MCP-1) by 3.0-, 15-, 2.0-, 7.6-, 11-, and 6.1-fold, respectively (p<0.05). PAI-1 protein expression induced by UTP was dependent on protein kinase C (PKC) and extracellular signal-regulated kinase (ERK), based on blockade by the PKC inhibitor Ro-31-8220 and the ERK inhibitor U0126, respectively. The rank order for enhanced expression of PAI-1 and alpha-SMA by nucleotides (UTPgammaS>>UDPbetaS>>ATPgammaS), the expression of P2Y2 receptors as the most abundantly expressed P2Y receptor in rat CFs and a blunted response to UTP in P2Y2(-/-) mice all implicate P2Y2 as the predominant P2Y receptor that mediates nucleotide-promoted profibrotic responses. Additional results indicate that P2Y2 receptor-promoted profibrotic responses in CFs are transient, perhaps as a consequence of receptor desensitization. We conclude that P2Y2 receptor activation is profibrotic in CFs; thus inhibition of P2Y2 receptors may provide a novel means to diminish fibrotic remodeling and turnover of extracellular matrix in the heart.

Inflammatory stress and idiosyncratic hepatotoxicity: hints from animal models

Adverse drug reactions (ADRs) present a serious human health problem. They are major contributors to hospitalization and mortality throughout the world (Lazarou et al., 1998; Pirmohamed et al., 2004). A small fraction (less than 5%) of ADRs can be classified as "idiosyncratic." Idiosyncratic ADRs (IADRs) are caused by drugs with diverse pharmacological effects and occur at various times during drug therapy. Although IADRs affect a number of organs, liver toxicity occurs frequently and is the primary focus of this review. Because of the inconsistency of clinical data and the lack of experimental animal models, how IADRs arise is largely undefined. Generation of toxic drug metabolites and induction of specific immunity are frequently cited as causes of IADRs, but definitive evidence supporting either mechanism is lacking for most drugs. Among the more recent hypotheses for causation of IADRs is that inflammatory stress induced by exogenous or endogenous inflammagens is a susceptibility factor. In this review, we give a brief overview of idiosyncratic hepatotoxicity and the inflammatory response induced by bacterial lipopolysaccharide. We discuss the inflammatory stress hypothesis and use as examples two drugs that have caused IADRs in human patients: ranitidine and diclofenac. The review focuses on experimental animal models that support the inflammatory stress hypothesis and on the mechanisms of hepatotoxic response in these models. The need for design of epidemiological studies and the potential for implementation of inflammation interaction studies in preclinical toxicity screening are also discussed briefly.

Alcohol, signaling, and ECM turnover

Alcohol is recognized as a direct hepatotoxin, but the precise molecular pathways that are important for the initiation and progression of alcohol-induced tissue injury are not completely understood. The current understanding of alcohol toxicity to organs suggests that alcohol initiates injury by generation of oxidative and nonoxidative ethanol metabolites and via translocation of gut-derived endotoxin. These processes lead to cellular injury and stimulation of the inflammatory responses mediated through a variety of molecules. With continuing alcohol abuse, the injury progresses through impairment of tissue regeneration and extracellular matrix (ECM) turnover, leading to fibrogenesis and cirrhosis. Several cell types are involved in this process, the predominant being stellate cells, macrophages, and parenchymal cells. In response to alcohol, growth factors and cytokines activate many signaling cascades that regulate fibrogenesis. This mini-review brings together research focusing on the underlying mechanisms of alcohol-mediated injury in a number of organs. It highlights the various processes and molecules that are likely involved in inflammation, immune modulation, susceptibility to infection, ECM turnover and fibrogenesis in the liver, pancreas, and lung triggered by alcohol abuse.

Plasminogen activator inhibitor-1 regulates integrin alphavbeta3 expression and autocrine transforming growth factor beta signaling

Fibrosis is characterized by elevated transforming growth factor beta (TGFbeta) signaling, resulting in extracellular matrix accumulation and increased PAI-1 (plasminogen activator inhibitor) expression. PAI-1 induces the internalization of urokinase plasminogen activator/receptor and integrin alphavbeta3 from the cell surface. Since increased alphavbeta3 expression correlates with increased TGFbeta signaling, we hypothesized that aberrant PAI-1-mediated alphavbeta3 endocytosis could initiate an autocrine loop of TGFbeta activity. We found that in PAI-1 knock-out (KO) mouse embryonic fibroblasts), alphavbeta3 endocytosis was reduced by approximately 75%, leaving alphavbeta3 in enlarged focal adhesions, similar to wild type cells transfected with PAI-1 small interfering RNA. TGFbeta signaling was significantly enhanced in PAI-1 KO cells, as demonstrated by a 3-fold increase in SMAD2/3-containing nuclei and a 2.9-fold increase in TGFbeta activity that correlated with an increase in alphavbeta3 and TGFbeta receptor II expression. As expected, PAI-1 KO cells had unregulated plasmin activity, which was only partially responsible for TGFbeta activation, as evidenced by a mere 25% reduction in TGFbeta activity when plasmin was inhibited. Treatment of cells with an alphavbeta3-specific cyclic RGD peptide (GpenGRGD) led to a more profound (59%) TGFbeta inhibition; a nonspecific RGD peptide (GRGDNP) inhibited TGFbeta by only 23%. Human primary fibroblasts were used to confirm that PAI-1 inhibition and beta3 overexpression led to an increase in TGFbeta activity. Consistent with a fibrotic phenotype, PAI-1 KO cells were constitutively myofibroblasts that had a 1.6-fold increase in collagen deposition over wild type cells. These data suggest that PAI-1-mediated regulation of alphavbeta3 integrin is critical for the control of TGFbeta signaling and the prevention of fibrotic disease.

Current experimental perspectives on the clinical progression of alcoholic liver disease

Chronic alcohol abuse is an important cause of morbidity and mortality throughout the world. Liver damage due to chronic alcohol intoxication initially leads to accumulation of lipids within the liver and with ongoing exposure this condition of steatosis may first progress to an inflammatory stage which leads the way for fibrogenesis and finally cirrhosis of the liver. While the earlier stages of the disease are considered reversible, cirrhotic destruction of the liver architecture beyond certain limits causes irreversible damage of the organ and often represents the basis for cancer development. This review will summarize current knowledge about the molecular mechanisms underlying the different stages of alcoholic liver disease (ALD). Recent observations have led to the identification of new molecular mechanisms and mediators of ALD. For example, plasminogen activator inhibitor 1 was shown to play a central role for steatosis, the anti-inflammatory adipokine, adiponectin profoundly regulates liver macrophage function and excessive hepatic deposition of iron is caused by chronic ethanol intoxication and increases the risk of hepatocellular carcinoma development.

New concepts in the pathogenesis of alcoholic liver disease

Alcoholic liver disease still represents an important cause for death and disability in most well-developed countries and is becoming a leading cause of disease in developing countries. It is now increasingly clear that, besides the formation of acetaldehyde, alcohol effects on the liver include oxidative stress, disturbances in methionine metabolism, endoplasmic reticulum stress, inflammatory/immune responses and adipokine imbalances. This article will discuss the most recent findings on the mechanisms by which alcohol abuse causes hepatic steatosis and steatohepatitis, and now it contributes to the progression of fibrosis. Although still incomplete, these data shed new light on the multifactorial pathogenesis of alcoholic liver disease and open new possibilities in the understanding of how gender and genetic factors can influence disease progression.

Characterization of a site on PAI-1 that binds to vitronectin outside of the somatomedin B domain

Vitronectin and plasminogen activator inhibitor-1 (PAI-1) are proteins that interact in the circulatory system and pericellular region to regulate fibrinolysis, cell adhesion, and migration. The interactions between the two proteins have been attributed primarily to binding of the somatomedin B (SMB) domain, which comprises the N-terminal 44 residues of vitronectin, to the flexible joint region of PAI-1, including residues Arg-103, Met-112, and Gln-125 of PAI-1. A strategy for deletion mutagenesis that removes the SMB domain demonstrates that this mutant form of vitronectin retains PAI-1 binding (Schar, C. R., Blouse, G. E., Minor, K. M., and Peterson, C. B. (2008) J. Biol. Chem. 283, 10297-10309). In the current study, the complementary binding site on PAI-1 was mapped by testing for the ability of a battery of PAI-1 mutants to bind to the engineered vitronectin lacking the SMB domain. This approach identified a second, separate site for interaction between vitronectin and PAI-1. The binding of PAI-1 to this site was defined by a set of mutations in PAI-1 distinct from the mutations that disrupt binding to the SMB domain. Using the mutations in PAI-1 to map the second site suggested interactions between alpha-helices D and E in PAI-1 and a site in vitronectin outside of the SMB domain. The affinity of this second interaction exhibited a K(D) value approximately 100-fold higher than that of the PAI-1-somatomedin B interaction. In contrast to the PAI-1-somatomedin B binding, the second interaction had almost the same affinity for active and latent PAI-1. We hypothesize that, together, the two sites form an extended binding area that may promote assembly of higher order vitronectin-PAI-1 complexes.