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Montfort C.V.,Liver Unit Hospital Clinic | Montfort C.V.,CIBER ISCIII | Matias N.,Liver Unit Hospital Clinic | Matias N.,CIBER ISCIII | And 18 more authors.
Journal of Hepatology | Year: 2012

Background & Aims: Steatohepatitis (SH) is associated with mitochondrial dysfunction and excessive production of superoxide, which can then be converted into H2O2 by SOD2. Since mitochondrial GSH (mGSH) plays a critical role in H2O2 reduction, we explored the interplay between superoxide, H2O2, and mGSH in nutritional and genetic models of SH, which exhibit mGSH depletion. Methods: We used isolated mitochondria and primary hepatocytes, as well as in vivo SH models showing mGSH depletion to test the consequences of superoxide scavenging. Results: In isolated mitochondria and primary hepatocytes, superoxide scavenging by SOD mimetics or purified SOD decreased superoxide and peroxynitrite generation but increased H2O2 following mGSH depletion, despite mitochondrial peroxiredoxin/thioredoxin defense. Selective mGSH depletion sensitized hepatocytes to cell death induced by SOD mimetics, and this was prevented by RIP1 kinase inhibition with necrostatin-1 or GSH repletion with GSH ethyl ester (GSHee). Mice fed the methionine-choline deficient (MCD) diet or MAT1A-/- mice exhibited reduced SOD2 activity; in vivo treatment with SOD mimetics increased liver damage, inflammation, and fibrosis, despite a decreased superoxide and 3-nitrotyrosine immunoreactivity, effects that were ameliorated by mGSH replenishment with GSHee, but not NAC. As a proof-of-principle of the detrimental role of superoxide scavenging when mGSH was depleted transgenic mice overexpressing SOD2 exhibited enhanced susceptibility to MCD-mediated SH. Conclusions: These findings underscore a critical role for mGSH in the therapeutic potential of superoxide scavenging in SH, and suggest that the combined approach of superoxide scavenging with mGSH replenishment may be important in SH. © 2012 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.


Romero-Gomez M.,University of Seville | Jover M.,University of Seville | Del Campo J.A.,University of Seville | Royo J.L.,Pablo De Olavide University | And 14 more authors.
Annals of Internal Medicine | Year: 2010

Background: Hepatic encephalopathy is a major complication of cirrhosis and is associated with a poor prognosis. Objective: To identify mutations in the gene sequence for glutaminase in humans that could be responsible for the development of hepatic encephalopathy in patients with cirrhosis. Design: Cohort study. Setting: Outpatient clinics in 6 Spanish hospitals. Patients: 109 consecutive patients with cirrhosis in the estimation cohort, 177 patients in the validation cohort, and 107 healthy control participants. Measurements: Patients were followed every 3 or 6 months until the development of hepatic encephalopathy or liver transplantation, death, or the end of the study. Results: The genetic analyses showed that glutaminase TACC and CACC haplotypes were linked to the risk for overt hepatic encephalopathy. Mutation scanning of the glutaminase gene identified a section in the promoter region where base pairs were repeated (a microsatellite). Over a mean follow-up of 29.6 months, hepatic encephalopathy occurred in 28 patients (25.7%) in the estimation cohort. Multivariable Cox models were used to determine the following independent predictors: Child-Turcotte-Pugh stage (hazard ratio [HR], 1.6 [95% CI, 1.29 to 1.98]; P = 0.001), minimal hepatic encephalopathy (HR, 3.17 [CI, 1.42 to 7.09]; P = 0.006), and having 2 long alleles of the microsatellite (HR, 3.12 [CI, 1.39 to 7.02]; P = 0.006). The association between 2 long alleles of the microsatellite and overt hepatic encephalopathy was confirmed in a validation cohort (HR, 2.1 [CI, 1.17 to 3.79]; P = 0.012). Functional studies showed higher luciferase activity in cells transfected with the long form of the microsatellite, which suggests that the long microsatellite enhances glutaminase transcriptional activity. Limitation: Other genes and allelic variants might be involved in the clinical expression of hepatic encephalopathy. Conclusion: This study identifies a genetic factor that is associated with development of hepatic encephalopathy in patients with cirrhosis. Primary Funding Source: Instituto de Salud Carlos III, Spanish Ministry of Health. © 2010 American College of Physicians.


Ordonez R.,University of León | Ordonez R.,CIBER ISCIII | Fernandez A.,University of León | Fernandez A.,CIBER ISCIII | And 14 more authors.
Journal of Pineal Research | Year: 2015

Autophagy is a process that maintains homeostasis during stress, although it also contributes to cell death under specific contexts. Ceramides have emerged as important effectors in the regulation of autophagy, mediating the crosstalk with apoptosis. Melatonin induces apoptosis of cancer cells; however, its role in autophagy and ceramide metabolism has yet to be clearly elucidated. This study was aimed to evaluate the effect of melatonin administration on autophagy and ceramide metabolism and its possible link with melatonin-induced apoptotic cell death in hepatocarcinoma (HCC) cells. Melatonin (2 mm) transiently induced autophagy in HepG2 cells through JNK phosphorylation, characterized by increased Beclin-1 expression, p62 degradation, and LC3II and LAMP-2 colocalization, which translated in decreased cell viability. Moreover, ATG5 silencing sensitized HepG2 cells to melatonin-induced apoptosis, suggesting a dual role of autophagy in cell death. Melatonin enhanced ceramide levels through both de novo synthesis and acid sphingomyelinase (ASMase) stimulation. Serine palmitoyltransferase (SPT) inhibition with myriocin prevented melatonin-induced autophagy and ASMase inhibition with imipramine-impaired autophagy flux. However, ASMase inhibition partially protected HepG2 cells against melatonin, while SPT inhibition significantly enhanced cell death. Findings suggest a crosstalk between SPT-mediated ceramide generation and autophagy in protecting against melatonin, while specific ASMase-induced ceramide production participates in melatonin-mediated cell death. Thus, dual blocking of SPT and autophagy emerges as a potential strategy to potentiate the apoptotic effects of melatonin in liver cancer cells. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.


Sia D.,Liver Unit Hospital Clinic | Sia D.,Italian National Cancer Institute | Alsinet C.,Liver Unit Hospital Clinic | Newell P.,Earle A Chiles Research Institute | And 3 more authors.
Current Pharmaceutical Design | Year: 2014

Induction of angiogenesis represents one of the major hallmarks of cancer. The growth of new vessels is crucial to provide malignant cells with an adequate supply of oxygen and nutrients. It is generally accepted that vascular endothelial growth factor (VEGF) is a major driver of the angiogenic process in physiological and pathological processes in both embryo and adult. VEGF is often found overexpressed in tumors, as well as its receptors VEGFR1 and VEGFR2. Hence, several different strategies have been designed to target VEGF signal transduction. In the last decades, multiple inhibitors have been therapeutically validated in preclinical models and several clinical trials. Neutralizing monoclonal antibodies against VEGF and small molecule tyrosine kinase inhibitors targeting VEGFRs have been shown to block its angiogenic activity, resulting in tumor vascular regression, anti-tumor effects and improvements in patient survival. However, side effects and lack of efficacy in some instances challenge the potential clinical impact of these therapies. This review examines the role of VEGF signaling in cancer and outlines the current status of anti-angiogenic therapies against VEGF pathway. © 2014 Bentham Science Publishers.


Guevara M.,Liver Unit Hospital Clinic | Guevara M.,Institute dInvestigacions Biomediques August Pi Sunyer
Hepatology | Year: 2012

Aims: In patients with cirrhosis and refractory ascites the role of beta-blockers in the development of paracentesis- induced circulatory dysfunction (PICD) is unknown. The aim of this study was to investigate the incidence of PICD before and after discontinuation of beta- blockers in patients with cirrhosis and refractory ascites. A self control cross-over study was performed. Methods: Patients with cirrhosis and refractory ascites treated with beta-blockers were selected. Heart rate, arterial pressure, and plasma renin concentrations (PRC) were collected before, immediately after and 1 week after largevolume paracentesis associated with intravenous albumin administration. Beta-blocker therapy was progressively discontinued after complete endoscopic eradication of varices. The clinical and biological evaluation was then repeated. The presence of PICD was defined as an increase in PRC of at least 50% above baseline 1 week after paracentesis. Results: Ten patients were included (nine men, mean age 59.1 6 10.7 years old). The MELD score was 17.7 6 4.4 and eight patients were Child Pugh C. When patients were given betablockers,the heart rate did not change immediately after paracentesis while mean arterial pressure significantly decreased; PICD developed in eight patients. After beta-blockers were discontinued, the heart rate significantly increased immediately after paracentesis and mean arterial pressure significantly decreased; PICD only developed in one patient; the difference in the incidence of PICD was significant when these same patients were treated with beta-blockers. Conclusions: The use of beta-blockers may be associated with a high risk of PICD in patients with cirrhosis and refractory ascites. © 2012.


Mari M.,Liver Unit Hospital Clinic | Morales A.,Liver Unit Hospital Clinic | Colell A.,Liver Unit Hospital Clinic | Garcia-Ruiz C.,Liver Unit Hospital Clinic | And 3 more authors.
Biochimica et Biophysica Acta - General Subjects | Year: 2013

Background: Mitochondria are the powerhouse of mammalian cells and the main source of reactive oxygen species (ROS) associated with oxygen consumption. In addition, they also play a strategic role in controlling the fate of cells through regulation of death pathways. Mitochondrial ROS production fulfills a signaling role through regulation of redox pathways, but also contributes to mitochondrial damage in a number of pathological states. Scope of review: Mitochondria are exposed to the constant generation of oxidant species, and yet the organelle remains functional due to the existence of an armamentarium of antioxidant defense systems aimed to repair oxidative damage, of which mitochondrial glutathione (mGSH) is of particular relevance. Thus, the aim of the review is to cover the regulation of mGSH and its role in disease. Major conclusions: Cumulating evidence over recent years has demonstrated the essential role for mGSH in mitochondrial physiology and disease. Despite its high concentration in the mitochondrial matrix, mitochondria lack the enzymes to synthesize GSH de novo, so that mGSH originates from cytosolic GSH via transport through specific mitochondrial carriers, which exhibit sensitivity to membrane dynamics. Depletion of mGSH sensitizes cells to stimuli leading to oxidative stress such as TNF, hypoxia or amyloid β-peptide, thereby contributing to disease pathogenesis. General significance: Understanding the regulation of mGSH may provide novel insights to disease pathogenesis and toxicity and the opportunity to design therapeutic targets of intervention in cell death susceptibility and disease. This article is part of a Special Issue entitled Cellular functions of glutathione. © 2012 Elsevier B.V.


Tarrats N.,Liver Unit Hospital Clinic | Moles A.,Liver Unit Hospital Clinic | Morales A.,Liver Unit Hospital Clinic | Garcia-Ruiz C.,Liver Unit Hospital Clinic | And 3 more authors.
Hepatology | Year: 2011

Tumor necrosis factor (TNF) has been implicated in the progression of many chronic liver diseases leading to fibrosis; however, the role of TNF in fibrogenesis is controversial and the specific contribution of TNF receptors to hepatic stellate cell (HSC) activation remains to be established. Using HSCs from wild-type, TNF-receptor-1 (TNFR1) knockout, TNF-receptor-2 (TNFR2) knockout, or TNFR1/R2 double-knockout (TNFR-DKO) mice, we show that loss of both TNF receptors reduced procollagen-α1(I) expression, slowed down HSC proliferation, and impaired platelet-derived growth factor (PDGF)-induced promitogenic signaling in HSCs. TNFR-DKO HSCs exhibited decreased AKT phosphorylation and in vitro proliferation in response to PDGF. These effects were reproduced in TNFR1 knockout, but not TNFR2 knockout, HSCs. In addition, matrix metalloproteinase 9 (MMP-9) expression was dependent on TNF binding to TNFR1 in primary mouse HSCs. These results were validated in the human HSC cell line, LX2, using neutralizing antibodies against TNFR1 and TNFR2. Moreover, in vivo liver damage and fibrogenesis after bile-duct ligation were reduced in TNFR-DKO and TNFR1 knockout mice, compared to wild-type or TNFR2 knockout mice. Conclusion: TNF regulates HSC biology through its binding to TNFR1, which is required for HSC proliferation and MMP-9 expression. These data indicate a regulatory role for TNF in extracellular matrix remodeling and liver fibrosis, suggesting that targeting TNFR1 may be of benefit to attenuate liver fibrogenesis. © 2011 American Association for the Study of Liver Diseases.


PubMed | University of Southern California and Liver Unit Hospital Clinic
Type: | Journal: Redox biology | Year: 2014

Alcoholic liver disease (ALD) is a major cause of chronic liver disease and a growing health concern in theworld. While the pathogenesis of ALD is poorly characterized key players identified in experimental models and patients, such as perturbations in mitochondrial structure and function, selective loss of antioxidant defense and susceptibility to inflammatory cytokines, contribute to ALD progression. Both oxidative stress and mitochondrial dysfunction compromise essential cellular functions and energy generation and hence are important pathogenic mechanisms of ALD. An important process mediating the mitochondrial disruption induced by alcohol intake is the trafficking of cholesterol to mitochondria, mediated by acid sphingomyelinase-induced endoplasmic reticulum stress, which contributes to increased cholesterol synthesis and StARD1upregulation. Mitochondrial cholesterol accumulation not only sensitizes to oxidative stress but it can contribute to the metabolic reprogramming in ALD, manifested by activation of the hypoxia inducible transcription factor 1 and stimulation of glycolysis and lactate secretion. Thus, a better understanding of the mechanisms underlying alcohol-mediated mitochondrial impairment and oxidative stress may lead to the identification of novel treatments for ALD. The present review briefly summarizes current knowledge on the cellular and molecular mechanisms contributing to alcohol-induced mitochondrial dysfunction and cholesterol accumulation and provides insights for potential therapeutic targets in ALD.


Mari M.,Liver Unit Hospital Clinic | Morales A.,Liver Unit Hospital Clinic | Colell A.,Liver Unit Hospital Clinic | Garcia-Ruiz C.,Liver Unit Hospital Clinic | And 2 more authors.
Redox Biology | Year: 2014

Alcoholic liver disease (ALD) is a major cause of chronic liver disease and a growing health concern in theworld. While the pathogenesis of ALD is poorly characterized key players identified in experimental models and patients, such as perturbations in mitochondrial structure and function, selective loss of antioxidant defense and susceptibility to inflammatory cytokines, contribute to ALD progression. Both oxidative stress and mitochondrial dysfunction compromise essential cellular functions and energy generation and hence are important pathogenic mechanisms of ALD. An important process mediating the mitochondrial disruption induced by alcohol intake is the trafficking of cholesterol to mitochondria, mediated by acid sphingomyelinase-induced endoplasmic reticulum stress, which contributes to increased cholesterol synthesis and StARD1upregulation. Mitochondrial cholesterol accumulation not only sensitizes to oxidative stress but it can contribute to the metabolic reprogramming in ALD, manifested by activation of the hypoxia inducible transcription factor 1 and stimulation of glycolysis and lactate secretion. Thus, a better understanding of the mechanisms underlying alcohol-mediated mitochondrial impairment and oxidative stress may lead to the identification of novel treatments for ALD. The present review briefly summarizes current knowledge on the cellular and molecular mechanisms contributing to alcohol-induced mitochondrial dysfunction and cholesterol accumulation and provides insights for potential therapeutic targets in ALD. © 2014 The Authors.


Moles A.,Liver Unit Hospital Clinic | Moles A.,Institute Investigaciones Biomedicas Of Barcelona | Tarrats N.,Liver Unit Hospital Clinic | Tarrats N.,Institute Investigaciones Biomedicas Of Barcelona | And 5 more authors.
Journal of Biological Chemistry | Year: 2012

Niemann-Pick disease (NPD) is a lysosomal storage disease caused by the loss of acid sphingomyelinase (ASMase) that features neurodegeneration and liver disease. Because ASMase-knock- out mice models NPD and our previous findings revealed that ASMase activates cathepsins B/D (CtsB/D), our aim was to investigate the expression and processing of CtsB/D in hepatic stellate cells (HSCs) from ASMase-null mice and their role in liver fibrosis. Surprisingly, HSCs from ASMase-knock-out mice exhibit increased basal level and activity of CtsB as well as its in vitro processing in culture, paralleling the enhanced expression of fibrogenic markers α-smooth muscle actin (α-SMA), TGF-β, and pro-collagen- α1(I) (Col1A1). Moreover, pharmacological inhibition of CtsB blunted the expression of α-SMA and Col1A1 and proliferation of HSCs from ASMase-knock-out mice. Consistent with the enhanced activation of CtsB in HSCs from ASMase-null mice, the in vivo liver fibrosis induced by chronic treatment with CCl4 increased in ASMase-null compared with wild-type mice, an effect that was reduced upon CtsB inhibition. In addition to liver, the enhanced proteolytic processing of CtsB was also observed in brain and lung of ASMase-knock-out mice, suggesting that the overexpression of CtsB may underlie the phenotype of NPD. Thus, these findings reveal a functional relationship between ASMase and CtsB and that the ablation of ASMase leads to the enhanced processing and activation of CtsB. Therefore, targeting CtsB may be of relevance in the treatment of liver fibrosis in patients with NPD. © 2012 by The American Society for Biochemistry and Molecular Biology, Inc.

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