SciELO - Scientific Electronic Library Online

vol.98 número11Prolapso rectal completoInflamación y perforación de divertículo solitario de ciego: Presentación de 5 casos y revisión de la literatura índice de autoresíndice de materiabúsqueda de artículos
Home Pagelista alfabética de revistas  

Servicios Personalizados




Links relacionados

  • En proceso de indezaciónCitado por Google
  • No hay articulos similaresSimilares en SciELO
  • En proceso de indezaciónSimilares en Google


Revista Española de Enfermedades Digestivas

versión impresa ISSN 1130-0108

Rev. esp. enferm. dig. vol.98 no.11 Madrid nov. 2006




Non-alcoholic fatty liver disease. From insulin resistance to mitochondrial dysfunction

Enfermedad grasa del hígado no alcohólica. Desde la resistencia a la insulina a la disfunción mitocondrial



J. A. Solís Herruzo, I. García Ruiz,
M. Pérez Carreras and M. T. Muñoz Yagüe

Departments of Gastroenterology and Hepatology. Research Center. University Hospital "12 de Octubre". Universidad Complutense. Madrid, Spain





Non-alcoholic fatty liver disease represents a set of liver lesions similar to those induced by alcohol that develop in individuals with no alcohol abuse. When lesions consist of fatty and hydropic degeneration, inflammation, and eventually fibrosis, the condition is designated non-alcoholic steatohepatitis (NASH). The pathogenesis of these lesions is not clearly understood, but they are associated with insulin resistance in most cases. As a result, abdominal fat tissue lipolysis and excessive fatty acid uptake by the liver occur. This, together with a disturbance of triglyceride export as VLDL, results in fatty liver development. Both the inflammatory and hepatocellular degenerative components of NASH are attributed to oxidative stress. Mitochondrial respiratory chain loss of activity plays a critical role in the genesis of latter stress. This may be initiated by an increase in the hepatic TNFa, iNOS induction, peroxynitrite formation, tyrosine nitration and inactivation of enzymes making up this chain. Consequences of oxidative stress include: lipid peroxidation in cell membranes, stellate cell activation in the liver, liver fibrosis, chronic inflammation, and apoptosis.

Key words: Non-alcoholic fatty liver disease. Insulin resistance. Mitochondrial dysfunction.



Alcohol-induced liver lesions belong to three different categories (1-3): a) fatty liver, where hepatocytes are filled with a big fat vacuole displacing the nucleus and other organelles towards the cell's periphery (macrovacuolar steatosis). On occasion, hepatocytes contain multiple fat droplets that will not displace the nucleus peripherally, allowing it to remain in its central position (microvacuolar steatosis); b) alcoholic hepatitis. These patients exhibit, together with liver steatosis, hepatocyte ballooning degeneration, alcoholic hyaline or Mallory bodies, megamitochondria, mixed inflammatory infiltrates with predominant polymorphonuclear cells, and both pericentral and pericellular fibrosis. All these changes are more common and severe in the centrolobular zone 3; and c) alcoholic liver cirrhosis, primarily micronodular that may secondarily evolve to macro-micronodular cirrhosis. Also cirrhoses with this etiology may become complicated with hepatocellular carcinoma.

These lesions, mainly those corresponding to alcoholic hepatitis, have been considered highly suggestive of alcohol abuse. However, as early as in the 1950s Zelman (4) and Werswater and Fainer (5) described the presence of liver steatosis and fibrosis associated with inflammatory infiltrates in the liver of obese patients. Also Thaler reported on several occasions -during the 60s and early 70s- apparently alcoholic lesions in non-drinking subjects. Hence Thaler suggested that the term "alcoholic hepatitis" be replaced by "fatty hepatitis", "Fettleberhepatitis", or "steatohepatitis" (6-8). Similar cases were further described during the 70s in obese (9-11) and diabetic (12-14) individuals, as well as in patients undergoing enteric bypass for morbid obesity (15,16). All these reports were received with skepticism as most authors were convinced that these patients were in fact heavy drinkers. In 1980, Ludwig et al. (17) coined the term "non-alcoholic steatohepatitis" (NASH) to designate these lesions that mimic those induced by alcohol in individuals with no alcohol abuse. NASH is currently considered a part in a wider spectrum of lesions including -in addition to NASH itself- non-alcoholic fatty liver, fatty liver and inflammation, and probably a high number of cryptogenic cirrhoses (18,19). To designate all this range of lesions the term "non-alcoholic fatty liver disease" (NAFLD) was proposed. The prognostic relevance of all these lesions is heterogeneous. While steatosis is a stable lesion that only develops into more severe forms in 3% of cases, NASH evolves to cirrhosis in 15-25% of cases (18,20). Many cryptogenic cirrhoses probably originate in NASH, with steatohepatitis signs disappearing over time (21-23). As with cirrhosis from other etiologies, NASH-derived cirrhosis may also result in hepatocellular carcinoma (24).

The diagnosis of NASH is not based on the presence of a specific liver lesion, but on the existence of a constellation of lesions including steatosis, hepatocyte hydropic degeneration, and inflammatory infiltrates. In addition, hyaline Mallory bodies, megamitochondria, and fibrosis in varying degrees are commonly found. A scoring system has been recently suggested to assess the various hepatic lesions of NAFLD, and to establish the histological diagnosis of NASH (19,25). A conceptual and critical diagnostic feature of NAFLD is absence of alcohol abuse. There is no unanimous view on what may be considered "non-abusive alcohol consumption" regarding NAFLD, but consumption is usually considered non-abusive when ethanol ingestion remains below 20-40 g/day in males and 20 g/day in females (26,27).

NAFLD is a common lesion in Western populations, and will become commoner in the future, as it is associated with insulin resistance, diabetes, and obesity. After viral infection and alcohol abuse, it currently represents the third most common cause of hypertransaminasemia. It is estimated that 17 to 33% of the general population have NAFLD, and the lesion present in 5.7 to 17% of this same population is NASH (28,29). When hypertransaminasemia has been studied for a cause in subjects with no viral infection markers and no alcohol abuse, NAFLD lesions are found in 40 to 90% of cases (29). In a study by ourselves some 20 years ago we found that NASH lesions had a prevalence of 5/100,000 population, an incidence of 0.9/100,000 population/year, and a frequency in liver biopsies of 1.9% and one in twelve alcoholic hepatitis cases (30,31). More recent reviews of this problem have shown that such incidence and prevalence have been on the rise for the past few years.

NAFLD has been identified in association with a high number of metabolic, surgical, and toxic conditions (secondary NAFLDs). However, the primary factor associated with NAFLD is metabolic syndrome, defined as the associated presence of at least three of the following changes in one individual: blood hypertension (≥ 130/85 mmHg), central obesity (waist > 102 cm in males; > 88 cm in females), fasting hyperglycemia (≥ 110 mg/dl), hypertriglyceridemia (> 150 mg/dl), and reduced HDL (< 40 mg/dl in males; < 50 mg/dl in females) (32). A common pathophysiologic feature in this syndrome is insulin resistance (33-35). In fact, NAFLD would represent the hepatic component of insulin resistance syndrome.


From insulin resistance to fatty liver

Insulin is the primary anabolizing hormone in the body. Its effect brings about an increased synthesis of proteins, glycogen, and lipids, facilitates glucose uptake by cells, and decreases glyconeogenesis and lipolysis. The mechanisms for such varied effects are only partially understood. In adipocytes and skeletal muscle cells the binding of its specific receptor by insulin is known to activate the receptor's tyrosine kinase, the latter's self-phosphorylation, and the phosphorylation in tyrosine/activation of IRS-1 (Insulin Receptor Substrate-1). This is followed by the activation of PI3K (Phosphatidyl Inositol-3 Kinase). This kinase activates a glucose transporter that is usually found within vesicles in the cytoplasm -Gluc-4 (glucose transporter 4)- and moves it unto the plasma membrane, thus facilitating cell glucose uptake (34,36,37) (Fig. 1). Within cells glucose is used an energy source, or stored as glycogen when not required. In the presence of insulin resistance, IRS-1 phosphorylation in tyrosine does not take place; cell glucose uptake stops; glucose is retained in the extracellular space and hyperglycemia occurs, which in turn stimulates insulin secretion by pancreatic β cells (38). Once the pancreas is depleted and can no longer compensate for hyperglycemia, type-II diabetes mellitus develops.

The cascade phenomena following the binding of insulin to its receptor is more extensive than previously mentioned. PI3K activation after IRS-1 phosphorylation activates phosphodiesterase, and as a consequence AMPc degradation and depletion. Absence of AMPc precludes PKA (Protein Kinase A) activation, and hence lipoprotein lipase (LPL) activation too (39). That is, neither triglyceride hydrolysis nor free fatty acid (FFA) release from fat tissue occur (40). A consequence of insulin resistance in fat tissue is that cAMP remains high, which activates PKA, which in turn activates LPL. This results in triglyceride degradation and FFA release into the blood. The lipogenic and anti-lipolytic effects of insulin are coordinated by the hormone's PI3K-mediated effects on SREBP (Sterol Regulatory Element Binding Protein), a transcription factor that plays an essential role in the activation of various genes involved in lipogenesis (acetyl-CoA carboxylase; fatty acid synthase; glycerol-3 phosphate acetyltransferase, etc.) (41), and in VLDL excretion (MTP, Microsomal Transfer Protein). Hence, in the absence of insulin activity, all these genes are repressed, and so is lipogenesis (42) (Fig. 1).

The effects of insulin on the liver slightly differ from those exerted on fat tissue and skeletal muscle, as insulin receptor phosphorylates another substrate -IRS-2 (43)- into tyrosine, which through PI3K and Akt-2/PKB phosphorylates and inactivates GSK3 (Glycogen Synthase Kinase-3), and the latter stops inhibiting glycogen synthase thus allowing an increase in the latter's activity (44). As a result, insulin increases glycogen synthesis in the liver. Liver insulin resistance results in opposite effects. It decreases glycogen synthesis and increases glycolysis, glyconeogenesis, and glucose release into the circulation. In addition, insulin stimulates -also through IRS-2 and SREBP activation- the expression of lipogenic genes determining the synthesis of fatty acids in the liver (45).

Factors playing a role in insulin resistance are probably multiple (46-48). Steatosis itself has been implied, as well as oxidative stress, FFAs, TNFα, and -as intracellular mediators- ceramide, IKKβ (49), NFkB, PKC-θ (Protein Kinase C-θ), JNK1 (Jun N-Terminal Kinase-1) (36,50-54), cytochrome CYP2E1 (55), and SOCS (56). The latter proteins interfere in insulin signal transmission, as they preclude IRS-1 and IRS-2 from coming into contact with insulin receptor (57) or induce proteasomal degradation for these substrates (58). Their overexpression in the liver induces insulin resistance and increased SREBP, which in turn originates steatosis (48). The role of liver steatosis in the pathogenesis of insulin resistance is supported by a number of observations. In the course of liver steatosis of any origin, insulin resistance also develops in a secondary manner. For instance, insulin resistance commonly develops in lipodystrophies (59,60), disturbed mitochondrial β-oxidation (61), or VLDL secretion defects (62). Similarly, the feeding of rats with fat-rich diets induces hepatic insulin resistance (47). In lipodystrophies, subcutaneous and visceral fat is mobilized, hypertriglyceridemia develops, and fat deposition in the liver occurs. On the other hand, mice lacking fat tissue develop severe liver and muscle steatosis, inability to activate PI3K through IRS-2, and hepatic insulin resistance (63). We also have a number of studies demonstrating that insulin resistance correlates with liver fat deposition (64). Both FFAs and TNFα are likely to interfere in the transmission of insulin-generated signals on inducing IRS-1 phosphorylation in serine 307 -rather than tyrosine (65-68). Phosphorylation in this serine is incompatible with simultaneous phosphorylation in tyrosine. Both TNFα and FFAs possibly bring about this phosphorylation following JNK1 (Jun-N-terminal Kinase-1) activation (65,69,70). JNK1 overactivation has been demonstrated in mice with NASH (71). NFkB release secondary to IKK-β activation has been involved in the pathogenesis of oxidative stress-induced insulin resistance (72).

As previously mentioned, huge amounts of FFAs are released into the circulation as a result of insulin resistance-associated lipolysis. Abdominal fat lipolysis is particularly important in the pathogenesis of NAFLD (73). Thus, for instance, almost two thirds of liver fat deposits in NAFLD have been seen to derive from circulating FFAs (74), and the severity of liver steatosis has been shown to correlate with visceral fat tissue rather than subcutaneous or peripheral fat tissue values (75). Removal of subcutaneous fat by liposuction solves none of NAFLD-related metabolic disorders (76). Indeed, insulin resistance, peripheral adiponectin, TNFα, IL-6, CRP, insulin, glucose, etc. remain all unchanged following such fat removal. In contrast, a reduction of visceral fat improves insulin resistance and other metabolic disturbances associated with NAFLD (77). Visceral fat has been shown to be particularly resistant to insulin activity (78), and is thus more easily hydrolyzed. In addition, based on its strategic position in the circulation of portal blood, the liver directly receives FFAs released during abdominal fat lipolysis. Fatty acid and glycerol plasma concentrations in patients and animals with NAFLD are strongly increased, and insulin can be seen to have a reduced capability in blocking the release of such lipolysis-derived products (79).

FFAs arriving in the liver activate nuclear receptor PPARα, which by forming a heterodimer with RXR (Retinoid X Receptor) induces the transcription of numerous genes involved in fatty acid catabolism and clearance (acyl-CoA oxidase, cytochrome P450, fatty acid-binding protein, microsomal triglyceride transfer protein, apolipoprotein B100, etc.) (80-82) (Fig. 2). Specifically, these proteins play a role in FFA utilization, triglyceride (steatosis) and phospholipid synthesis, glyconeogenesis (hyperglycemia), or oxidation in mitochondria, peroxisomes, or microsomes. These three oxidation types are highly significant, as they may contribute to the cell's oxidative stress.B-oxidation in mitochondria may lead to ROS (Reactive Oxygen Species) formation, mainly superoxide anions (O2-), during oxidative phosphorylation (83). B-oxidation in peroxisomes leads to hydrogen peroxide formation, whereas oxidation in microsomes -with the involvement of cytochrome P450- determines the formation of superoxide anions and dicarboxylic acids. Triglyceride buildup in liver cells would result from liver FFA uptake in amounts greater than those that may be used or exported into the blood as VLDLs. To this day no altered incorporation of FFAs into triglycerides, phospholipids, or cholesterol esters has been demonstrated in patients with NAFLD (79). On the contrary, some studies have shown that triglyceride exports as VLDLs are reduced in patients with NAFLD due to their lower incorporation into apolipoprotein B100 (84,85). Polymorphisms in the MTP (Microsomal Triglyceride Transfer Protein) promoter have been seen in these patients that may explain such lipid export defect (86,87). MTP incorporates triglycerides into apolipoprotein B in the endoplasmic reticulum and Golgi apparatus, thus giving rise to VLDL formation and facilitated lipid release from liver cells (88-90). When MTP activity is reduced, lipid export from hepatocytes decreases, cells retain their lipids, and liver steatosis ensues. Liver steatosis is a common occurrence in diseases with MTP mutations (91). In chronic HCV infection (mainly genotype 3), commonly associated with NAFLD, liver MTP activity is significantly decreased (92). Therefore, NAFLD's steatosis would on the one hand result from greater FFA uptake by the liver as a result of insulin resistance-derived lipolysis, and on the other hand from disturbed triglyceride export into the circulation as VLDLs (Fig. 2).


From steatosis to non-alcoholic steatohepatitis

Oxidative stress

If insulin resistance plays a fundamental role in the pathogenesis of fatty liver, then oxidative stress is probably pivotal in the evolution from steatosis to NASH and the more advanced lesions of NAFLD. It has been posited that NASH would result from two aggressions. The first one would be represented by fatty liver; the second by oxidative stress (93,94). We have plenty of evidence suggesting that oxidative stress is present in NAFLD. Patients and animals with this lesion have increased liver levels of malonic aldehyde (MDA) (95,96), 4-hydroxynonenal (4-HNE) (97), 3-tyrosine nitrated proteins (79,95,96), and 8-hydroxydeoxyguanosine (97,98), all of them markers for lipid, protein, and DNA oxidative lesion, respectively. Furthermore, blood thioredoxin levels, another oxidative stress marker, are elevated in NASH (99), while those of antioxidizing factors are decreased (96,100,101). Genes coding for most antioxidizing factors have an ARE (Antioxidant-Response Element) in common that responds to transcription factors Nrf1 and Nrf2 (Nuclear factor erythroid 2-related factor). These two factors act as heterodimers, and make up complexes with Small-Maf and other bZIF proteins (102). Nrfs factors are normally sequestered in the cytoplasm (103). When a cell suffers from oxidative stress, Nrfs factors are translocated into the nucleus, bind AREs in antioxidizing genes, and induce their expression (104,105). The relevance of these antioxidizing factors in the pathogenesis of NAFLD is supported by studies in Nrf1-/- mice, which lack Nrf1 and develop a decreased expression of genes with AREs, steatosis, necrosis, apoptosis, liver inflammation, and pericellular and pericentral fibrosis, in addition to oxidative stress (106). Consistent with this is the finding that antioxidizing (Glutathione S Transferase) gene expression is diminished in patients with NAFLD (107).

The consequences of oxidative stress on cells are manifold. They induce cell membrane lipid peroxidation, and cell degeneration and necrosis, cell death by apoptosis (108,109), proinflammatory cytokine expression, liver stellate cell activation, and fibrogenesis (93,94,110).

Source of oxidative stress

The role of mitochondria

While the source of oxidative stress in NASH is probably multiple (fatty acid oxidation, microsomal cytochromes, siderosis, cytokines, Kupffer cells, etc.), mitochondrial dysfunction seems to play a predominant role. Mitochondria are involved in both FFA β-oxidation and ROS generation (83,111-114). Several studies have shown that mitochondria in patients with NASH are abnormal from both a morphologic and a functional perspective. In these patients mitochondria are big, swollen, with scarce criptae, and usually with paracrystalline inclusions (79,115). These changes are very similar to those found in mitochondrial myopathies arising from disturbances in the mitochondrial respiratory chain (MRC) (116). In addition, [13C]CO2 generation from 13C-methionine and ATP resynthesis after fructose overload are severely reduced in patients with liver steatosis (117,118). Both problems suggest that mitochondrial function, in addition to mitochondrial morphology, is altered in patients with NASH.

Mitochondria are the primary site for FFA β-oxidation. A number of steps may be distinguished in this process (83,119):

(α) FFA uptake by mitochondria. An enzyme, CPT-1 (Carnitine Palmitoyl Transferase-I) and a translocase play a role in this process, and long-chain fatty acids must be previously bound to carnitine. Once the fatty acid has entered the mitochondria and is found in the mitochondrial matrix, carnitine is released back into the cytoplasm. Carnitine depletion (120-122), CPT-I deficiency (123), or a defective translocase may alter fatty acid uptake by mitochondria, and prevent their β-oxidation. This may contribute to fatty acid retention in the cytoplasm, and their subsequent re-esterification in triglycerides (Fig. 3).

In a study by ourselves in patients with NASH we found normal intrahepatic levels of both free and total carnitine (124), which was consistent with other authors' findings in obese and alcoholic patients with fatty liver (122, 125); similarly, the measurement of CPT-I activity in the liver of patients with NASH revealed normal values (124), and hence we may not attribute cytoplasmic triglyceride build up to FFAs not entering the mitochondria.

(β) The second step in this mitochondrial fatty acid oxidation process includes a range of successive b-oxidations leading to acetyl-CoA and short-chain fatty acids-CoA formation, and NAD+ to NADH conversion (126). Few studies have measured fatty acid b-oxidation in NAFLD. With indirect methods fatty acid b-oxidation has been presumed to be increased in these patients (79, 127). By directly measuring mitochondrial (palmitic acid) and peroxisomal (lignoceric acid) β-oxidation in ob/ob mice with NAFLD and NASH lesions we found that oxidation was significantly increased for both fatty acids (95). These results are consistent with the findings by Diehl’s team in this same type of mice (128,129).

Such β-oxidation increase has been attributed to insulin resistance, and hence to increased lipolysis and FFA uptake in the liver (41,79). FFAs play a role in the activation of transcription factor PPARα (Peroxisome Proliferator-Activated Receptor α), which in turn activates the expression of genes involved in fatty acid β-oxidation (130,131) (Fig. 3). (χ) NADH resulting from β-oxidation is re-oxidized to NAD+ in a process designated oxidative phosphorylation, which leads to ATP formation. The latter represents the only energy source that may be used by cells. This phosphorylation includes a number of enzyme complexes located at the inner mitochondrial membrane (complexes I to V), which are designated the mitochondrial respiratory chain (MRC). In this chain NAD+ and FADH2 electrons pass from one complex to the next, and eventually combine with oxygen and protons to form water. This process is coupled with another concomitant one where mitochondrial matrix protons are sent to the intermembrane space of mitochondria, thus generating an electrochemical gradient between the matrix and this space. When these protons go back to the mitochondrial matrix via ATP synthase (complex V), they determine the conversion of ADP into ATP, and hence the electrochemical energy built up in the intermembrane space is used in the formation of cell-usable energy (83,119,132). Along this oxidative phosphorylation process some electrons usually escape, and give rise to ROS –mainly O2 –– formation after binding mitochondrial matrix oxygen (133,134). When oxidative phosphorylation is deficient due to low MRC activity, not only ATP formation decreases, but electrons escaping the system increase and ROS formation is higher (126) (Fig. 4). As is the case with NASH, such ROS formation would be enhanced when liver FFA uptake and β-oxidation are increased. It is also enhanced in diabetes mellitus, where glucose oxidation represents a significant provision of electrons to MRC.

Information available on the function of oxidative phosphorylation and MRC in patients with NASH is very limited. Caldwell et al. (115) found that MRC complex I and III activity was normal in platelet mitochondria from patients with NASH, and Sanyal et al. (79) found no defects in this chain’s enzyme expression when studying muscle tissue from a patient with NASH. We have directly studied the activity of all MRC enzyme complexes in the liver of patients with NASH (124). In this study we were first to demonstrate that these complexes’ activity was reduced by 30 to 50% versus control activity. This defect compromises both complexes with mitochondria gene-encoded (complexes I, III, IV, V) and nuclear geneencoded (complex II) components. Consistent with these findings were the reports by Haque et al. (135), who published that cytochrome c oxidase –one of MRC complexes– activity was reduced. While the cause of these enzymatic defects remained unexplained, we saw that these complexes’ activity was inversely correlated to blood TNFα levels, body mass index, and HOMA index to assess insulin resistance (124).

In order to gain a deeper insight in the study of factors potentially responsible for MRC hypofunction, we used an animal NAFLD model that reproduces many of the disturbances commonly seen in humans. Mice of the ob/ob (Lep-/-) type have their leptin gene neutralized, and thus lack this hormone; as a result they experience polyfagia and weight gain, and develop insulin resistance, hyperglycemia, and hyperlipemia (136). Histological, the liver of animals studied by us had steatosis in 42% of hepatocytes, as well as hydropic degeneration, Mallory hyaline, and inflammatory infiltrates. That is, these animals met histological criteria for NASH. The study of MRC activity in these mice showed the presence of a defect similar to that found in patients with NASH. MRC enzyme activity was reduced by 40 to 60% versus healthy animals (137). Hence, these ob/ob mice seem to represent a fine experimental model to research the etiopathogenesis of mitochondrial dysfunction as found in patients with NAFLD.

MRC dysfunction as found in these mice allows to predict that both electron escape and ROS formation are likely increased in them (138). Indeed, the measurement of substances reacting with thiobarbituric acid (TBARS), a marker of oxidative stress, showed highly elevated levels. These findings are consistent with those already mentioned suggesting the presence of oxidative stress in the liver of patients with NASH (79,96,128,139-141).

Mitochondrial dysfunction mechanisms

Mechanisms potentially involved in mitochondrial dysfunction either in patients with NAFLD or ob/ob mice are varied. One may well be oxidative stress itself. MDA and 4-HNE, two products resulting from cell lipid peroxidation, are known to inhibit cytochrome c oxidase (MRC complex IV) activity after making up a number of conjugates with this complex’s peptics (142,143). Furthermore, ROS may damage both mitochondrial DNA (mtDNA) (144,145) and mitochondrial iron-sulfur cluster enzymes (138), thus leading to MRC hypofunction (146). Such mitochondrial DNA (mtDNA) lesions, which are difficult to repair in mitochondria (147), should impact the expression of complexes I, III, IV, and V in this chain, as mtDNA codes for 13 polypeptides making up these complexes. In accordance with this, Haqué et al. (135) found that patients with NASH had mtDNA depletion. The presence of oxidative stress in cells may initiate a series of vicious circles contributing to increase mtDNA damage, and to induce a greater mitochondrial disturbance (132,148).

Despite such evidence, findings in our studies with ob/ob mice do not support the role of oxidative stress as the causal factor for mitochondrial dysfunction. In effect, treating these animals with N-acetyl-cysteine (NAC) via the peritoneal route for 3 months markedly reduced liver TBARS concentration, but could not improve MRC complex activity or liver histological lesions (95). NAC inability to improve NAFLD histology has been reported also by other authors (96). These results, together with the fact that MRC complex II activity –with components not encoded in mtDNA– is also diminished in NAFLD and ob/ob mice, render the role of oxidative stress in the pathogenesis of this mitochondrial defect uncertain. Nevertheless, it is essential that experiments are repeated using antioxidants preferentially acting on mitochondria –e.g., superoxide dismutase analogues– before definitely excluding the role of oxidative stress (149).

Another important factor to consider in the pathogenesis of mitochondrial dysfunction is TNFα. There is strong evidence available advocating for the role of this cytokine in the pathogenesis of NASH (150,151). High blood TNFα levels have been found in patients with NASH (124,152-155), and we found that reduced MRC activity correlated with increased blood TNFα (124). In ob/ob mice we saw that TNFα concentrations in liver tissue were some 20-fold higher than in normal mice (137). In a previous study we demonstrated that treating cells with TNFα increases ROS, decreases messenger RNA for some ATPase components, and reduces the number of peptides making up ATPase and cytochrome c oxidase (156). The source of this hepatic TNFα is likely not one, since fat tissue, as well as hepatocytes and Kupffer cells may produce TNFα (150,157,158). Abdominal fat tissue may be a significant source for liver TNFα, as its passage through the liver is mandatory. In obese subjects fat tissue is infiltrated by macrophages (159,160), which may release TNFα besides adipocytes themselves (161). Preadipocytes exhibit some antimicrobial and phagocytic properties, just as macrophages do, and may also potentially transdifferentiate themselves into macrophages (162). Potential stimuli for TNFα release are varied (adipocyte cytokines, lipoperoxide phagocytosis, endotoxins). Furthermore, FFAs released during abdominal fat lipolysis may themselves induce TNFα expression both in the adipose tissue (163) and hepatocytes (164). This effect would occur via NFκB activation. FFAs would give rise to Bax translocation into lysosomes, and facilitate cathepsin B release to the cytoplasm, which would –via IKKβ– activate NFκB (165). 

Increased TNFα production would be a part of the chronic liver inflammation status that is present in liver steatosis. As a result of oxidative stress and FFA liver uptake Kupffer cells, IKKβ, and NFκB would become activated (165, 166). This transcription factor increases gene expression for TNFα, TGFβ, IL-8, IL-6, and IL-1β, among other factors. These may reproduce many of the histological changes usually found in NAFLD. For example, IL-8 induces neutrophil chemotaxis, TNFα, hepatocyte necrosis/apoptosis, TGFβ, stellate cell activation, liver fibrosis, and Mallory body formation.

 Biological effects by TNFα may be antagonized by adiponectin (167). This is an adipocyte-produced hormone with antilipogenic effects that inhibits fat from building up in the liver and other non-fat tissues, and hence prevents NAFLD, NASH, and liver inflammation and fibrosis development (168-171). The administration of recombinant adiponectin to ob/ob mice reduces hepatomegaly, fatty acid synthesis, and inflammation, while increasing fatty acid oxidation at the same time (168). Mice producing no adiponectin develop severe fibrosis following exposure to Cl4C, but this effect may be avoided if mice are infected with an adiponectin-expressing adenovirus (169). The antiinflammatory effect is probably exerted through a number of mechanisms, including reduced TNFα production by fat-tissue macrophages (167,172), NFκB pathway inhibition via AMPc (173), and inhibited macrophage activation (174). Decreased steatosis results from PPARα and cAMP-dependent kinase activation. This increases fatty acid oxidation and lipid export, and decreases lipogenesis (175). Via this same pathway, adiponectin enhances insulin sensitivity (176-179), and may revert many NAFLD-related disturbances. Decreased fibrosis is mediated by its antiproliferating and apoptotic effects on liver stellate cells (171). In metabolic syndrome, including NAFLD, blood adiponectin levels are decreased (153,180-182), which relates to central fat extent, increased liver steatosis, and liver insulin resistance (183,184). In contrast with other adipokines, circulating adiponectin levels are lower in obese subjects, particularly in visceral obesity. When visceral fat is diminished by losing weight, circulating adiponectin –and adiponectin mRNA– levels significantly increase in fat tissue (162). These changes are concurrent with and opposed to those experienced by TNFα and IL-6. These two cytokines inhibit adiponectin mRNA expression.

In a previous study, we found proof of TNFα’s negative effect on mitochondria. This cytokine induced relevant morphologic and functional changes on mitochondria. After incubating cells with TNFα for 8 hours, mitochondria swelled, became rounded, lost their septa, lightened their matrix, and broke their external membrane (185). In addition, our study revealed that TNFα may interfere with electron flow in MRC complexes I and III (185,186). This cytokine determines electron retention in cytochrome b, so the latter may donate such retained electrons to oxygen so that superoxide anions are formed (185). In fact, many NAFLD-related disorders may be explained by TNFα’s biological effects, as this factor not only induces MRC dysfunction, but also increases cell resistance to insulin, induces the expression of several proinflammatory cytokines and enzymes (including iNOS [Inducible Nitric Oxide Synthase], and brings about cell death by apoptosis or necrosis, among other things.

The critical role of TNFα in the pathogenesis of NAFLD and mitochondrial dysfunction is supported by results obtained in ob/ob mice treated for 3 months with anti-TNFα (infliximab) through the peritoneal route. While this therapy was insufficient to fully normalize TNFα levels in liver tissue, it did suffice to strikingly normalize or improve complex I, II, III, and V activity, to decrease β-oxidation activity, and to regress liver histology almost to normal (95). The effect we observed on β-oxidation has also been seen by Li et al. (128), and may be attributed to TNFα actions on insulin sensitivity (99,187), oxidative stress (99), and stearoyl-CoA desaturase (128), an enzyme involved in fatty acid synthesis (188). Simultaneous improvement of mitochondrial dysfunction and histological lesions after therapy with anti-TNFα antibodies allows to advocate for a role of TNFα in the pathogenesis of both disorders, and suggest that mitochondrial defects may well participate in lesion development.

The multiple biological effects of TNFα include iNOS expression induction (189), particularly when its activity is combined with that of IL-1β, IFNγ, and endotoxin (190). This enzyme catalyzes L-arginine oxidation in the presence of oxygen to give nitric oxide (NO). A normal liver expresses only endothelial NOS. However, under given circumstances –for example, under the effects of TNFα– liver iNOS expression strikingly increases, and the liver generates great amounts of NO (191). This TNFα effect is mediated by transcription factor NFκB (192), whose activity is greatly increased in ob/ob mice (128). In our study we found that the liver of these mice had, in addition to significantly increased levels of TNFα, also a marked induction of mitochondrial iNOS. Such enzymatic induction is no doubt dependent upon TNFα, as its expression dramatically decreased in obese mice treated with anti-TNFα, and approached control levels. The study by Laurent et al. also supports a non-activation of the iNOS pathway in ob/ob mice (128), as very high nitrite, nitrate, and 3-tyrosine nitrated protein concentrations were found in the liver. 

These findings may have pathogenic implications, since NO and other nitrogen-derived reagents may alter both mitochondrial and MRC function (193). Indeed, NO reacts with cytochrome c oxidase (complex IV), interrupts electron passage, and blocks their binding of oxygen (194). On the other hand, peroxynitrite (ONOO–), a product resulting from NO reaction with O2 , is an activity inhibitor for various proteins, including some MRC components (195,196). In vitro studies have shown that peroxynitrite may inactivate complexes I, II, V, cytochrome c (196-198), and also complex III under selected circumstances (199). Mechanisms through which peroxynitrite exerts these effects are varied and include its oxidative potential (200), and its ability to damage DNA (201), nitrate protein tyrosine residues, and generate 3-tyrosine nitrated proteins (202). The presence of 3-tyrosine nitrated proteins in tissues is a marker of tissue aggression by peroxynitrite radicals (203). Hence, we searched for such proteins in the liver of ob/ob mice.

Using immunofluorescence techniques we found that 3-tyrosine nitrated proteins was largely increased in obese mice when compared to control mice. These findings suggest that liver proteins in obese mice have been damaged by peroxynitrite radicals or derivatives. To gain a deeper insight on the origin of 3-tyrosine nitrated proteins, we looked for these proteins in a mitochondrial protein extract. Also in this case we saw that proteins in these organelles had been damaged by peroxynitrite. Moreover, after immunoprecipitating these proteins with anti-3-nitrotyrosine, we observed that a number of MRC components, at least cytochrome c and protein ND4, a component of complex I, had been 3-tyrosine nitrated.

Considering that MRC enzyme nitration is associated with a decrease in their catalytic activity (204), such nitration is likely to have been responsible for their low enzyme activity. In order to assess the role of peroxynitrite and reactive derivatives (205) in the pathogenesis of this disorder, we treated ob/ob mice with uric acid through the intraperitoneal route for three months. This acid rapidly reacts with peroxynitrite to form inactive nitrogenous urates (205,206). Therefore, uric acid is considered a natural neutralizer for peroxynitrite (205,207) and reactive derivatives (205,206). Treating mice with uric acid has been shown to reduce 3-tyrosine nitrated protein formation (205,206), and to prevent neurologic lesion progression in multiple sclerosis experimental model (203,208). Uric acid therapy effects in ob/ob mice were dramatic, as liver lipoperoxide and 3-tyrosine nitrated protein levels decreased, specifically decreasing cytochrome c and MRC ND4 peptide 3-tyrosine nitration. These effects were associated with a normalization of MRC complexes I and V activity, and a marked improvement of complexes II and III. Finally, this therapy led to the regression of liver lesions, and a recovery of the liver structure’s normal appearance. Uric acid effects on liver lesions support the role of peroxynitrite not only in MRC dysfunction, but also in the pathogenesis of lesions.

Results from our studies prompt us to suggest that liver TNFα –probably from abdominal fat tissue or enhanced expression in hepatocytes by FFAs– induces iNOS, and hence a greater formation of NO. This radical, when in the presence of O2, originates peroxynitrite radicals, which would bind MRC proteins and determine a decrease in their activity. Similar effects to those reported with uric acid have been seen when ob/ob mice were treated with MnTBAP (Manganese [III] 5,10,15,20 Benzoic Acid Porphyrin), an analogue of Mn superoxide dismutase (MnSOD) that turns O2 into H2O2 (96). Besides a reduction in oxidative phosphorylation and ATP formation, decreased MRC enzyme activity increases the number of electrons escaping the system; these electrons bind oxygen and then give rise to ROS formation. Such electron leak would be particularly high in situations where FFA provision to the liver for mitochondrial oxidation –as is the case with NAFLD– is elevated. This would be the origin of higher lipoperoxide levels as found in the liver of these obese mice. 

Other sources of oxidative stress

While mitochondrial dysfunction plays a predominant role in ROS generation, ROS may also come from FFA oxidation in peroxysomes and microsomes, and from Kupffer cell activation. In the obese and in patients with NASH, CYP2E1 activity is increased (209-213), likely induced by FFAs or ketones (214). This microsomal enzyme, besides taking part in the degradation of xenobiotics, induces FFA ω-oxidation (215), during which ROS are generated (216,217). The real significance of ROS from this source in the pathogenesis of human NASH remains to be demonstrated. Kupffer cells may also generate ROS via the NADPH-oxidase system (218). In experimental NASH models these cells have been shown to be activated, and to possess a high number of endotoxin receptors (166,219,220). Various factors may play a role in these cells’ activation. One would be lipoperoxide phagocytosis; another, the phagocytosis of endotoxins from the intestine (219).

Consequences of oxidative stress

ROS may induce lipid peroxidation, particularly for unsaturated fatty acids in cell membranes. The impact of such aggression is manifold. 

1. On the one hand it has an impact on membrane physico-chemical properties, which in turn has an impact on membrane receptor and enzyme activity, antigen expression, intercellular interactions (221-223), and membrane permeability. Changes may occur that compromise cell viability (passage of calcium into cells) (224) and condition cell death through necrosis as a result of the latter.

2. A lesion characteristic of NASH is liver fibrosis. It initially has a pericellular and pericentral distribution in Rapapport’s lobule area 3, but in advanced stages alters lobule architecture and takes on the pattern of micronodular cirrhosis. Cells primarily involved in the production of such fibrosis include liver stellate cells (LSCs). In a normal liver LSCs are in a latent state, and cannot produce extracellular matrix components. When the liver is damaged these cells become activated, change their morphology and function, and synthesize the various components of extracellular matrix (225-227). In human and experimental NASH, these cells have been shown to be activated and in greatly increased numbers (228-230). Mechanisms conducing to liver fibrosis in NASH are probably multiple.

α) Oxidative stress may induce LSC activation, and hence help stimulate liver fibrogenesis. This effect may occur following the activation of transcriptional factors NFκB and c-Myb. ROS may lead to IκB degradation in the cytoplasm, which conditions the release of transcription factor NFκB and its nuclear translocation (231). This effect would follow IKK (IκB Kinase)activation and IκB phosphorylation. In activated LSCs NFκB activity is increased and NFκB p50/p65 heterodimer may be found in the nucleus. Similarly, oxidative stress may induce gene expression of factor c-Myb and its binding to DNA (232). This transcription factor may play a role in the expression of smooth muscle actin, and in LSC contractility, differentiation, and proliferation (233). These cells may become activated by the phagocytosis of apoptotic bodies resulting from hepatocyte death (234).

β) In addition, lipid peroxidation-derived reactive aldehydes, including MDA and 4-HNE, may take part in liver fibrogenesis. Indeed, Chojkier et al. (235) showed that MDA significantly increased the expression of messenger RNA (mRNA) for collagen α1(I) in human fibroblast cultures. Maher et al. (236,237) found that collagen synthesis doubled up when fibroblasts were cultured with MDA. Findings consistent with these were reported by other investigators (238-241). While mechanisms of this effect are not unique, conjugates made up of reactive aldehydes with protein amino acids or sulphydryl radicals are likely to play a role (242). Such conjugate formation has been demonstrated in animal models with lipid peroxidation induction, and in a number of clinical circumstances with active fibrogenesis (241,243-247). On the other hand, antioxidant therapies decrease the formation of such conjugates, and prevent fibrogenesis (241,246,248). In a previous study we found evidence that aldehyde conjugates are involved in increased collagen expression (110,249.), since treating cells with p-hydroximercuribenzoate (pHMB) or pyridoxal-5´-phosphato (P5P) abolished the effects of both MDA and an oxidizing combination (ferrous chloride, ascorbic acid, cytric acid) on collagen expression. In these studies we determined that these aldehydes exert their effects through elements located between sequences -116 and -110 pb in the collagen α1 (I) promoter, and that transcription factors Sp1 and Sp3 act as mediators for this stimulus. These factors recognize G+C-rich sequences (250), and act as expression stimulating factors for a wide variety of genes, including the collagen α1(I) gene (250-254).

χ) In patients with insulin resistance and NASH, blood leptin levels are usually increased (255). Leptin is a 16 kDa peptide expressed by gene obese (Ob) (256) that is released by adipocytes and has varied metabolic effects, with the most significant of these being related to body weight and energy expenditure (257). TNFα is a major inducer (258). Together with metabolic effects, it has been seen to exert a powerful fibrogenic effect (259). Leptin-lacking ob/ob mice are particularly resistant to liver fibrosis development (260,261), but lose such resistance when exogenous leptin is administered (260). On the other hand, leptin administration enhances fibrosis as induced by other aggressions (262). High circulating leptin levels, which relate to fibrosis severity (266), have been found in patients with chronic hepatitis C, alcoholic liver disease, or NASH (255,263-265). The mechanisms through which leptin exerts these fibrogenic effects require further study, but several have been mentioned. Some have found that leptin directly stimulates LSCs (259,267), and others that this effect would be indirectly exerted after inducing TGFβ (Transforming Growth Factor-β) release from Kupffer, stellate, and endothelial cells (259-261,268). Some have shown evidence that it may delay extracellular matrix degradation after increasing TIMP-1 expression (269), and others that it stimulates LSC proliferation (270) and inhibits LSC apoptosis (271). Finally, leptin may induce oxidative stress by acting on MRC (272,273). It might well activate the aforementioned fibrogenic mechanisms through such oxidative stress.

δ) Other fat tissue hormones may also behave in a fibrogenic manner. Angiotensin II and norepinephrine may act directly on LSCs and induce their activation (274, 275). Osteopontin may lead to this through its proinflammatory effects (276). Mice lacking osteopontin have been seen to be protected against liver inflammation and fibrosis when on a choline-methionine-deficient diet.

ε) Steatosis itself may be a fibrogenesis-stimulating factor. NAFLD may exhibit fibrosis in the absence of necroinflammatory activity (228-277), fibrosis extent as experimentally induced is influenced by dietary fat types (278).

f) Another factor closely linked to obesity, liver steatosis, and the progression of liver disease –including chronic hepatitis C and NASH– is type-2 diabetes mellitus and insulin resistance (279,280). Type-2 diabetes includes peripheral insulin resistance, and high blood insulin levels, hence insulin may likely play some role in fibrosis progression. In fact, Hickman et al. found a significant association between blood insulin levels and increased fibrosis (281). Similarly, other authors have confirmed such association of insulin resistance with fibrosis severity in chronic hepatitis C (282,283). In this regard LSCs have been shown to possess insulin receptors, and thus this hormone may contribute to these cells' proliferation (284). This proliferative effect of insulin may take place by stimulating the MAPK (MAP kinase) pathway (285), which is closely related to cell growth. In addition, insulin increases TGFβ (286) and CTGF production (287).

γ) Finally, LSC and hence fibrogenesis activation may be an indirect consequence of hepatocyte apoptosis. This type of cell death yields apoptotic body formation –these bodies are phagocyted by macrophages or LSCs themselves, determine TGFβ release, and the latter activates LSCs (288,289). 

3. NFκB activation, which brings about oxidative stress, may explain the chronic inflammatory status of the liver in NAFLD (165,166), as it induces the expression of genes for numerous proinflammatory factors, including TNFα (290), interleukins 2, 6 and 8, ICAM-1 (291), MCP-1 (292), MIP-2 (293), CINC (Cytokine-Induced Neutrophil Chemoattractant) (294), and several proinflammatory enzymes (lipoxygenase, cyclooxygenase, iNOS) (231). At this point, TNFα, on activating NFκB, starts a new vicious circle that helps increase inflammation. Our studies (95), as those by Li et al. (128), show that treating ob/ob mice with anti-TNFα reverts or deletes liver infiltrates. On the other hand, the binding of reactive aldehydes (MDA, 4-HNE) to hepatocyte surface proteins may modify these proteins’ antigenic structure and initiate an immune response contributing to the inflammatory response seen in patients with NASH (295).

4. While mechanisms leading to Mallory hyaline formation are little understood, reactive aldehydes resulting from oxidative stress and TGFβ are also likely involved. In effect, TGFβ may activate transglutaminase, and the latter may result in the formation of cytokeratin polymers by establishing transversal links between lysine molecules in some cytokeratin chains and glutamine molecules in other cytokeratin chains (296).

5. In NASH hepatocyte death results not only from necrosis but also from apoptosis (297-300). Several pathways and factors may lead to this programmed death, including oxidative stress itself, TNFα, and FFAs. (α) ROS increase the expression of Fas receptors in the surface of hepatocytes, and thus may induce death by apoptosis (297). This effects has been attributed to NFκB activation, as this factor may increase cell death receptor expression (301,302); however, NFκB mainly behaves as a cell survival factor by inducing the expression of various enzymes (Mn-SOD, iNOS) or multiple antiapoptotic factors (Mcl-1, cFLIP, IAPs, Bcl-XL, A1) (192,303). The binding of Fas ligand to Fas receptor initiates a cascade of events in which the binding of adapting protein FADD (Fas-Associated Death Domain) to Fas, caspase 8 activation with eventually caspase 3 activation (304), Bid (BH3 interacting domain death) cleavage (305), fragment tBid translocation to the outer mitochondrial membrane, and binding of Bak (Bcl-2 antagonist/killer) and Bax (Bcl-2-associated X protein) by this fragment –which induces these proteins’ activation and increased mitochondrial membrane permeability– all play a role. In this way cytochrome c and other proapoptotic proteins leave the mitochondrial intermembrane space [Smac/DIABLO (Second mitochondrial-derived activator of caspase/Direct IAP-binding protein with low pI); AIF (Apoptosis inducing factor), endonuclease G] (306-309) and enter the cytoplasm. In the cytoplasm cytochrome c forms a complex with cytosol factor Apaf-1 (Apoptotic protease activating factor-1), ATP, and procaspase 9 (apoptosome), which leads to the latter’s activation, and then to procaspase 3 activation (310-312). Caspase 3 starts cell degradation and death by apoptosis (313). This latter process includes DNA degradation, nuclear and cellular fragmentation, and apoptotic body formation. These bodies may undergo phagocytosis by macrophages and other neighboring cells, and become fully degradated in their lysosomes. Another consequence of cytochrome c leaving mitochondria is that it interferes with electron flow through MRC.

As a result, ROS formation increases (314), and a new vicious cycle begins, which will worsen the disturbance.

Oxidative stress through NFκB activation may induce TNFα formation, and this factor may in turn induce apoptosis in hepatocytes (315,316). In fact, this cytokine may originate cell death both by apoptosis and necrosis, depending upon the cell’s energy status, as apoptosis is an active process using up huge energy amounts (317). TNFα action follows a pathway partly similar to that of FasL, as on binding its receptor (TNFR-1) forms a complex (complex I) made up with TRADD (TNF Receptor-Associated Protein with Death Domain), RIP (Receptor-Interacting Protein), and TRAF-2 (TNF Receptor-Associated Factor-2). This complex initiates a survival pathway where NFκB, BclXL, Mcl-1, Gadd45β, c-FLIP, IAPs, and A1 play a role (303,318,319). On the other hand, this molecular complex undergoes a number of changes and gives rise to another complex known as DISC (Death-inducing signaling complex) (complex II), which is bound by FADD. This leads to the activation of caspase 8, and the latter cleaves Bid to its truncated form, tBid, which permeabilizes mitochondria as was mentioned above (316). In addition, after the binding of TNFα to its receptor, sphingomyelinase becomes activated and generates ceramide from cell membrane-derived sphingomyelin (316). Ceramide induces cell apoptosis through various pathways, including its direct action on mitochondrial membrane pores, and inducing glutathione depletion (320,321). Furthermore, in previous studies in our laboratory (156) we showed that, at least partly, TNFα-related cytotoxicity is mediated by ROS.

To conclude, fatty acids may also play a relevant role in cell death. Evidence suggests that fatty acid accumulation in non-adipose cells is associated with cell dysfunction and death (322,323). This phenomenon has been designated lipotoxicity. This toxicity may contribute to the pathogenesis of various conditions. For instance, long-chain fatty acid deposition in pancreatic β cells or cardiomyocytes of diabetic rats induces death in these cells (324,325). The severity of myocardiopathy in diabetic patients has been seen to be related to the extent of myocardial triglyceride deposition (326). The mechanism through which triglyceride or FFA deposition results in these lesions or dysfunction is unknown. Fibroblasts and endothelial cells exposed to high long-chain saturated fatty acid concentrations reduce their proliferation and die (327). Death has been suggested to occur by apoptosis, which has been at least demonstrated in cardiomyocytes, pancreas β cells, and hematopoietic cells exposed to palmitic or stearic acid (328, 329). These proapoptotic effects would develop through at least two different mechanisms: a) by increasing lysosomal permeability, thus facilitating cathepsin B release, and favoring TNFα expression (164); b) by increasing mitochondrial permeability through JNK, thus facilitating cytochrome c release (330). Some authors have implicated ceramide as a second messenger for cell death. This mediator derives from sphingomyelin hydrolysis in cell membranes, and is used by TNFα to induce cell apoptosis (331). As was mentioned above, ceramide favors mitochondrial pore aperture, but other cell targets such as increased nitric oxide (332,333), CAPK (Ceramide-Activated Protein Kinase), PKCζ (Protein Kinase Cζ), “CAPP (Ceramide-Activaded Protein Phosphatase), MAPK (Mitogen Activated Protein Kinase), JNK (c-Jun N-terminal Kinase), and NFκB (334,335) have been considered as well.



This study was performed with Investigation Grant number 08/2005 from “Fundación Mutua Madrileña”, Madrid, Spain.



1. French SW, Nash J, Shitabata P, Kachi K, Hara C, Chedid A, et al. Pathology of alcoholic liver disease. Semin Liver Dis 1993; 13: 154-9.        [ Links ]

2. Harrison DJ, Burt AD. Pathology of alcoholic liver disease. In:Hayes PC, editor. Alcoholic Liver Disease. Bailliere’s Clin Gastroenterol 1993; 7: 641-62.        [ Links ]

3. Liu YC. Histopathology of alcoholic liver disease. In: McCullough AJ, editor. Alcoholic liver Disease. Clin Liver Dis 1998; 2: 753-63.        [ Links ]

4. Zelman S. The liver in obesity. Arch Intern Med 1952; 90: 141-56.        [ Links ]

5. Werswater JD, Fainer D. Liver impairment in the obese. Gastroenterology 1958; 34: 686-93.        [ Links ]

6. Thaler H. Die Fettleber und ihre pathogenetische Beziehung zur Lebercirrhosis. Virchows Arch Path Anat 1962; 335: 180-210.        [ Links ]

7. Thaler H. Leber Biopsie. Berlin:Springer-Verla; 1969. p. 176.        [ Links ]

8. Thaler H. Die Fettleber, ihre Ursachen und Begleitkrankheiten. Dtsch med Wschr 1962; 87: 1049-55.        [ Links ]

9. Kern WH, Heder AH, Payne JH, DeWind LT. Fatty metaborphosis of the liver in morbid obesity. Arch Oathol 1973; 96: 342-6.        [ Links ]

10. Galambos JT, Wills CE. Relationship between 505 paired liver tests and biopsies in 242 obese patients. Gastroenterology 1978; 74:1191-5.        [ Links ]

11. Adler M, Schaffner F. Fatty liver hepatitis and cirrhosis in obese patients. Am J Med 1979; 67: 811-6.        [ Links ]

12. Creutzfeldt W, Frerichs H, Sickinger K. Liver diseases and diabetes mellitus. In: Popper H, Schaffner F, editors. Progress in liver diseases. Vol. III. London: William Heinemann Med Books Ltd; 1970. p. 371-407.        [ Links ]

13. Falchuk KR, Fiske SC, Haggitt RC, Federman M, Trey C. Pericellular hepatic fibrosis and intracellular hyalin in diabetic mellitus. Gastroeneterology 1980; 78: 535-41.        [ Links ]

14. Itoh S, Tsukada Y, Motomure Y, Ichinoe A. Five patients with nonalcoholic diabetic cirrhosis. Acta Hepatogastroenterol 1979; 26: 90-7.        [ Links ]

15. DeWind LT, Payne JH. Intestinal bypass surgery for morbid obesity. Long-term results. JAMA 1978; 236: 2298-301.        [ Links ]

16. Campbell JM, Hung TK, Karam JH,Forsham PH. Jejunoileal bypass as a treatment of morbid obesity. Arch Intern Med 1977; 137: 602-10.        [ Links ]

17. Ludwig J, Viggiano RT, McGill DB. Nonalcoholic steatohepatitis: Mayo Clinic experiences with a hitherto unnamed disease. Mayo Clin Proc 1980; 55: 342-8.        [ Links ]

18. Matteoni CA, Younossi ZM, Gramlich T, Boparal N, Liu YC, Mc-Cullough AJ. Nonalcoholic fatty liver disease: a spectrum of clinical and pathological severity. Gastroenterology 1999; 116: 1413-9.        [ Links ]

19. Brunt EM, Janney CG, Bisceglie AM, Neuschwander-Tetri BA, Bacon BR. Nonalcoholic steatohepatitis: a proposal for grading and staging the histological lesions. Am J Gastoenterol 1999; 94: 2467-74.        [ Links ]

20. Caldwell SH, Hylton AI. The clinical outcome of NAFLD including cryptogenic cirrhosis. In: Farrell GC, George J, Hall PM, McCullough AJ, editors. Fatty liver disease. NASH and related disorders. Blackwell Publ Ltd Malden; 2005. p. 168-80.        [ Links ]

21. Poonawala A, Nair SP, Thuluvath PJ. Prevalence of obesity and diabetes in patients with crytogenic cirrhosis: a case study. Hepatology 2000; 32: 689-692.        [ Links ]

22. Caldwell SH, Oelsner DH, Iezzoni JC, Hespenheide EE, Battle EH, Driscoll CJ. Cryptogenic cirrhosis: clinical characterization and risk factors for underlying disease. Hepatology 1999; 29: 664-9.        [ Links ]

23. Ioannou GN, Weiss N, Kowdley KV, Dominitz JA. Is obesity a risk factor for cirrhosis-related death or hospitalization? A population-based cohort study. Gastroenterology 2003; 125: 1053-9.        [ Links ]

24. Ratziu V, Bonyhay L, Di Martino V, Charlotte F, Cavallaro L, Sayegh-Tainturier MH, et al. Survival, liver failure, and hepatocellular carcinoma in obesity-related cryptogenic cirrhosis. Hepatology 2002; 35: 1485-93.        [ Links ]

25. Kleiner DE, Brunt EM, Natta MV, Behling C, Contos MJ, Cummings OW, et al. Design and validation of a histological scoring system for nonalcoholic fatty liver disease. Hepatology 2005; 41: 1313-21.        [ Links ]

26. Newschwander-Tetri BA, Caldwell SH. Nonalcoholic steatohepatitis: summary of an AASLD single topic conference. Hepatology 2003; 37: 1202-19.        [ Links ]

27. George J, Farell GC. Practical approach to the diagnosis and management of people with fatty liver disease. In: Farrell GC, George J, Hall PM, McCullough AJ, editors. Fatty liver disease. NASH and related disorders. Blackwell Publ. Ltd. Malden. 2005: 181-93.        [ Links ]

28. Younossi ZM, Diehl AM, Ong JP. Nonalcoholic fatty liver disease: An agenda for clinical research. Hepatology 2002; 35: 746-52.        [ Links ]

29. McCullough AJ. The epidemiology and risk factors of NASH. In: Farell GC, George J, de la M Hall P, McCullough AJ, editors. Fatty liver disease. NASH and related disorders. Blackwell Publ Ltd Malden 2005: 23-37.        [ Links ]

30. Moreno Sánchez D, Solís Herruzo JA, Vargas Castrillón J, Colina Ruiz-Delgado F, Lizasoain Hernández M. Esteatohepatitis no alcohólica. Estudio clínico-analítico de 40 casos. Med Clin (Barc) 1987; 89: 188-93.        [ Links ]

31. Vargas Castrillón J, Colina Ruiz-Delgado F, Moreno Sánchez D, Solís Herruzo JA. Esteatohepatitis no alcohólica. Estudio histopatológico de 40 casos. Med Clin (Barc) 1988; 90: 563-8.        [ Links ]

32. National Institute of Health. The third report of the National Cholesterol Education Program Expert Panel on Detection Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III. Bethesda MA: National Institute of Heath. 2001: NIH Publications 01-2610.        [ Links ]

33. Marchesini G, Brizi M, Morselli-Labate AM, Bianchi G, Bugianesi G, McCullough AJ, et al. Association of nonalcoholic fatty liver disease with insulin resistance. Am J Med 1999; 107: 450-5.        [ Links ]

34. Samuel VT, Shulman GI. Insulin resistance in NAFLD: Potential mechanisms and therapies. In: Farell GC, George J, de la M Hall P, McCullough AJ, editors. Fatty liver disease. NASH and related disorders. Blackwell Publ Ltd Malden; 2005. p. 38-54.        [ Links ]

35. Marchesini G, Burgianesi E. NASH as part of the metabolic (insulin resistance) syndrome. In: Farell GC, George J, de la M Hall P, Mc-Cullough AJ, editors. Fatty liver disease. NASH and related disorders. Blackwell Publ Ltd Malden; 2005. p. 55-65.        [ Links ]

36. Virkamaki A, Ueki K, Kahn CR. Protein-protein interaction in insulin signaling and the molecular mechanisms of insulin resistance. J Clin Invest 1999; 103: 931-43.        [ Links ]

37. Saltier AR, Kahn CR. Insulin signaling and the regulation of glucose and lipid metabolism. Nature 2001; 414: 799-806.        [ Links ]

38. Chitturi S, Abeygunasekera S, Farell GC, Holmes-Walker J, Hui JM, Fung C, et al. NASH and insulin resistance: insulin hypersecretion and specific association with the insulin resistance. Hepatology 2002; 35: 373-9.        [ Links ]

39. Kitamura T, Kitamura Y, Kuroda S, Hino Y, Ando M, Kotani H, et al. Insulin-induced phosphorylation and activation of cyclic nucleotide phosphodiesterase 3B by the serine-threonine kinase Akt. Mol Cell Biol 1999; 19: 6286-96.        [ Links ]

40. Anthonsen MW, Ronnstrand L, Wernstedt C, Degerman E, Holm C. Identification of novel phosphorylation sites in hormone sensitive lipase that are phosphorylated in response to isoproterenol and govern activation properties in vitro. J Biol Chem 1998; 273: 215-21.        [ Links ]

41. Senyal AJ. Insulin resistance and nonalcoholic fatty liver disease. In: Arroyo V, Navasa M, Foros X, Bataller R, Sánchez-Fueyo A, Rodés J. editors. Update in treatment of liver disease. Barcelona: Ars Medica; 2005. p. 279-96.        [ Links ]

42. De Fronzo RA, Ferranini E. Insulin resistance. A multifaceted syndrome responsible for NIDDM, obesity, hypertension, dyslipidemia, and atherosclerotic cardiovascular disease. Diabetes Care 1991; 14: 173-94.        [ Links ]

43. Previs SF, Withers DJ, Ren JM, White MF, Shulman GI. Contrasting effects of IRS-1 versus IRS-2 gene disruption on carbohydrate and lipid metabolism in vivo. J Biol Chem 2000; 275: 38990-4.        [ Links ]

44. Cross DA, et al. Inhibition of glycogen synthetase kinase-3 by insulin mediated by protein kinase B. Nature 1995; 378: 385-9.        [ Links ]

45. López JM, Bennett MK, Sánchez HB, Rosenfeld JM, Osborne TF. Sterol regulation of acetyl coenzyme A carboxylase: A mechanism for coordinate control of cellular lipid. Proc Natl Acad Sci USA 1996; 93: 1049-53.        [ Links ]

46. Perseghin G, Peterson K, Shulman GI. Cellular mechanism of insulin resistance: potencial links with inflammation. Int J Obes Relat Metab Disord 2003; 27: S6-S11.        [ Links ]

47. Samuel VT, Liu Z-X, Qu X, Elder BD, Bilz S, Befroy D, et al. Mechanism of hepatic resistance in non alcoholic fatty liver disease. J Biol Chem 2004; 279: 3245-53.        [ Links ]

48. Ueki K, Kondo T, Tseng Y-H, Kahn CR. Central role of suppressors of cytokine signaling proteins in hepatic steatosis, insulin resistance, and the metabolic syndrome in the mouse. Proc Natl Acad Sci USA 2004; 101: 10422-7.        [ Links ]

49. Gao Z, et al. Serine phosphorylation of insulin receptor substrate 1 by inhibitor κB kinase complex. J Biol Chem 2002; 277: 48115-21.        [ Links ]

50. Shepherd PR, Kahn BB. Glucosa transporters and insulin action: implications for insulin resistance and diabetes mellitus. N Engl J Med 1999; 341: 248-57.        [ Links ]

51. Buglianesi E, McCullough AJ, Marchesini G. Insulin resistance: A metabolic pathway to chronic liver disease. Hepatology 2005; 42: 987-1000.        [ Links ]

52. Combettes-Souverain M, Issad T. Molecular basis of insulin action.Diabetes Metab 1998; 24: 477-89; .        [ Links ]

53. Kim JK, Fillmore JJ, Chen Y, Yu C, Moore IK, Pypaert M, et al. Tissue-specific overexpression of lipase causes tissue-specific insulin resistance. Proc Natl Acad Sci USA 2001; 98: 7522-7.        [ Links ]

54. Kim SP, Ellmerer M, Van Citters GW, Bergman RN. Primacy of hepatic insulin resistance in the development of metabolic syndrome induced by an isocaloric moderate-fat diet in the dog. Diabetes 2003; 52: 2453-60.        [ Links ]

55. Schattenberg JM, Wang Y, Sing R, Rigoli RM, Czaja MJ. Hepatocyte CYP2E1 overexpression and steatohepatitis lead to impaired hepatic insulin signalling. J Biol Chem 2005; 280: 9887-94.        [ Links ]

56. Farrell GC. Signalling links in the liver. Knitting SOCS with fat and inflammation. J Hepatol 2005; 43: 193-6.        [ Links ]

57. Ueki K, Kondo T, Kahn CR. Suppressor of cytokine signaling I (SOCS-1) and SOCS-3 cause insulin resistance through inhibition of tyrosine phosphorylation of insulin receptor substarte proteins by discrete mechanisms. Mol Cell Biol 2004; 24: 5434-46.        [ Links ]

58. Rui L, Yuan M, Frantz D, Shoelson SE, White MF. SOCS-1 and SOCS-3 block insulin signaling by ubiquitin-mediated degradation of IRS1 and IRS2. J Biol Chem 2002; 277: 42394-8.        [ Links ]

59. Petersen KF, Oral EA, Dufour S, Befroy D, Ariyan C, Yu C, et al. Leptin reverses insulin resistance and hepatic steatosis in patients with severe lipodystrophy. J Clin Invest 2002; 109: 1345-50.        [ Links ]

60. Sutinen J, Hakkinen AM, Westerbacka J, Seppala-Lindroos A, Vehkavaara S, Halavaara J, et al. Increased fat accumulation in the liver in HIV-infected patients with antiretroviral therapy-associated lipodystrophy. AIDS 2002; 16: 2183-93.        [ Links ]

61. Petersen KF, Befroy D, Dufour S, Dziura J, Rothman DL, et al. Mitochondrial dysfunction in the elderly: possible role in insulin resistance. Science 2003; 300: 1140-2.        [ Links ]

62. Ibdah JA, Perlegas P, Zhao Y, Angdisen J, Borgerink H, Shadoan MK, et al. Mice heterozygous for a defect in mitochondrial trifunctional protein develop hepatic steatosis and insulin resistance. Gastroenterology 2005; 128: 1381-90.        [ Links ]

63. Kim JK, Gavrilova O, Chen Y,Reitman ML, Shulman GI. Mechanism of insulin resistance in A-ZIP/F-1 fatless mice. J Biol Chem 2000; 275: 8456-60.        [ Links ]

64. Tikkainen M, Tamminen M, Hakkinen AM, Bergholm R, Vehkavaara S, Halavaara J, et al. Liver-fat accumulation and insulin in obese woman with previous gestational diabetes. Obes Res 2002; 10: 859-67.        [ Links ]

65. Hirosumi J, Tuncman G, Chang L, Gorgun CZ, Uysal KT, Maeda K, et al. A central role for the JNK in obesity and insulin resistance. Nature 2002; 420: 353-6.        [ Links ]

66. Sykiotis GP, Papavassiliou AG. Serine phosphorylation of insulin receptor substrate-1: a novel target for the reversal of insulin resistance. Mol Endocrinol 2001; 15: 1864-9; .        [ Links ]

67. Hotamisligil GS, Peraldi P, Budavari A, Ellis R, White MF, Spiegelman BM. IRS-1-mediated inhibition of insulin receptor tyrosine kinase activity in TNF-alpha- and obesity-induced insulin resistance. Science 1996; 271: 665-8.        [ Links ]

68. Shulman GI. Cellular mechanisms of insulin resistance. J Clin Invest 2000; 106: 171-6.        [ Links ]

69. Aguirre V, Werner ED, Giraud J, Lee YH, Shoelson SE, While MF. Phosphorylation of serine307 in insulin receptor substrate-1 blocks interactions with the insulin receptors and inhibits insulin action. J Biol Chem 2002; 277: 1531-7.        [ Links ]

70. Bennett BL, Satoh Y, Lewis AJ. JNK: A new therapeutic target for diabetes. Curr Opin Pharmacol 2003; 3: 420-5.        [ Links ]

71. Schattenberg JM, Singh R, Wang Y, Lefkowitch JH, Rigoli RM, Scherer PE, et al. JNK1 but not JNK2 promotes the development of steatohepatitis in mice. Hepatology 2006; 43: 163-72.        [ Links ]

72. De la Pena A, Leclercq I, Field J, George J, Jones B, Hou HY, et al. NF-kappaB activation, rather than TNF, mediates hepatic inflammation in a murine modelo f steatohepatitis. Gastroenterology 2005; 129: 1663-74.        [ Links ]

73. Nielsen S, Guo Z, Johnson CM, Hersrud DD, Jensen MD. Splachnic lipólisis in human obesity. J Clin Invest 2004; 113: 1582-8.        [ Links ]

74. Donnelly KL, Smith CI, Schwarzenberg SJ, Jessurun J, Boidt MD, Parks EJ. Sources of fatty acids stored in liver and secreted via lipoproteins in patients with non alcoholic fatty liver disease. J Clin Invest 2005; 115: 1343-51.        [ Links ]

75. Kelley DE, McKolanis TM, Hegazi RAF, Kuller LH, Calan SC. Fatty liver in type 2 diabetes mellitus: Relation to regional adiposity,fatty acids, and insulin resistance. Am J Physiol Endocrinol Matabol 2003; 285: E906-E916.        [ Links ]

76. Klein S, Fontana L, Young L, Coggan AR, Kilo C, Patterson BW, et al. Absence o fan effect of liposuction on insulin action and risk factors fro coronary artery disease. N Engl J Med 2004; 350: 2549-57.        [ Links ]

77. Uusitupa M, Lindi V, Louheranta A, Salopuro T, Lindstrom J, Tuomilehto J. Long-term improvement in insulin sensitivity by changing lifestyles of people with impaired glucosa tolerance: 4-year results from the Finnish Diabetes Prevention Study. Diabetes 2003: 52: 2532-8.        [ Links ]

78. Masuzaki H, Paterson J, Shinyama H, Morton NM, Mullins JJ, Seckl JR, et al. A transgenic model of visceral obesity and the metabolic syndrome. Science 2001; 294: 2166-70.        [ Links ]

79. Sanyal AJ, Campbell-Sargent C, Mirshahi F, Rizzo WB, Contos MJ, Sterling RK, et al. Nonalcoholic steatohepatitis: association of insulin resistance and mitochondrial abnormalities. Gastroenterology 2001; 120: 1183-92.        [ Links ]

80. Landier JF, Thomas C, Grober J, Duez H, Percevault F, Souidi M, et al. Statin induction of liver fatty acid-binding protein (L-FABP) gene expression is peroxisome proliferator-activated receptor-alphadependent. J Biol Chem 2004; 279: 45512-8.         [ Links ]

81. Ameen C, Edvardsson U, Ljungberg A, Asp L, Akerblad P, Tuneld A, et al. Activation of peroxisome proliferator-activated receptor alpha increases the expression and activity of microsomal triglyceride transfer protein in the liver. J Biol Chem 2005; 280: 1224-9.        [ Links ]

82. Linden D, Lindberg K, Oscarsson J, Claesson C, Asp L, Li L, et al. Influence of peroxisome proliferator-activated receptor alpha agonists on the intracellular turnover and secretion of apolipoprotein (Apo)B-100 and ApoB-48. J Biol Chem 2002; 277: 23044-53.        [ Links ]

83. Pessayre D, Mansouri A, Fromenty B. Non-alcoholic steatosis and steatohepatitis. V. Mitochondrial dysfunction in steatohepatitis. Am J Physiol Gastrointest Liver Physiol 2002; 282: G193-G199.        [ Links ]

84. Charlton M, Sreekumar R, Rasmussen D, Lindor K, Nair KS. Apolipoprotein synthesis in non-alcoholic steatohepatitis. Hepatology 2002; 35: 898-904.        [ Links ]

85. Sreekumar R, Rosado B, Rasmussen D, Charlton M. Hepatic gene expression in histologically progressive nonalcoholic steatohepatitis. Hepatology 2003; 38: 244-51.        [ Links ]

86. Bernard S, Touzet S, Personne I, Lapras V, Bondon PJ, Berthezane F, et al. Association between microsomal triglyceride transfer protein gene polymorphism and the biological features of liver steatosis in patients with type II diabetes. Diabetologia 2000; 43: 995-9.        [ Links ]

87. Namikawa C, Shu-Ping Z, Vysellar JR, Nozaki Y, Nemoto Y, Ono M, et al. Polymorphisms of microsomal triglyceride transfer protein gene and manganese superoxide dismutase gene in non-alcoholic steatohepatitis. J Hepatol 2004; 40: 781-6.        [ Links ]

88. Ohashi K, Ishibashi S, Osuga J, Tozawa R, Harada K, Yahagi N, et al. Novel mutations in the microsomal triglyceride transfer protein gene causing abetalipoproteinemia. J Lipid Res 2000; 41: 1199-204.        [ Links ]

89. Tran K, Thorne-Tjomsland G, DeLong CJ, Cui Z, Shan J, Burton L, et al. Intracellular assembly of very low density lipoproteins containing apolipoprotein B100 in rat hematoma McA-RH777. J Biol Chem 2002; 277: 31187-200.        [ Links ]

90. Hussain MM, Iqbal J, Anwar K, Rava P, Day K. Microsomal triglyceride transfer protein: a multifunctional protein. Front Biosci 2003; 8: S500-S506.        [ Links ]

91. Watterau JR, Aggerbeck LP, Bouma ME, Eisenberg C, Munck A, Hermier M, et al. Absence of microsomal triglyceride transfer protein in individuals with abetalipoproteinemia. Science 1992; 258:999-1001.        [ Links ]

92. Mirandola S, Realdon S, Iqbal J, Gerotto M, Dal Pero F, Bortoletto G, et al. Liver microsomal triglyceride transfer protein is involvel in hepatitis C liver steatosis. Gastroenterology 2006; 130: 1661-89.        [ Links ]

93. Chittury S, Farrell GC. Etiopathogenesis of nonalcoholic steatohepatitis. Semin Liver Dis. 2001; 21: 27-41.        [ Links ]

94. James O, Day C. Non-alcoholic steatohepatitis: another disease of affluence. Lancet 1999; 353: 1634-6.        [ Links ]

95. Solís-Herruzo JA, García-Ruiz I, Díaz-Sanjuan T, Del Hoyo P, Colina F, Muñoz-Yagüe T. Uric acid and anti-TNFα antibody improve mitochondrial respiratory chain dysfunction in ob/ob mice. Hepatology 2005; 42: 634.        [ Links ]

96. Laurent A, Nicco C, van Nhieu JT, Borderie D, Chéreau C, Conti F, et al. Pivotal role of superoxide anion and beneficial effect of antioxidant molecules in murine steatohepatitis. Hepatology 2004; 39: 1277-85.        [ Links ]

97. Seki S, Kitada T, Sakaguchi H. Clinicopathological significance of oxidative cellular damage in non-alcoholic fatty liver diseases. Hepatol Res 2005; 33: 132-4.        [ Links ]

98. Seki S, Kitada T, Yamada T, Sakaguchi H, Nakatani K, Wakasa K. In situ detection of lipid peroxidation and oxidative DNA damage in non-alcoholic fatty liver disease. J Hepatol 2002; 37: 56-62.        [ Links ]

99. Sumida Y, Nakashima T, Yoh T, Furutani M, Hirohama A, Kakisaka Y, et al. Serum thioredoxin levels as a predictor of steatohepatitis in patients with nonalcoholic fatty liver disease. J Hepatol 2003; 38: 32-8.        [ Links ]

100. Yesilova Z, Yaman H, Oktenli C, Ozcan A, Uygun A, Fakir E, et al. Systemic markers of lipid peroxidation and antioxidants in patients with nonalcoholic fatty liver disease. Am J Gastroenterol 2005; 100: 850-5.        [ Links ]

101. Nobili V, Pastore A, Gaeta LM, Tozzí G, Comparcola D, Sartorelli MR, et al. Glutathione metabolism and antioxidant enzymes in patients affected by nonalcoholic steatohepatitis. Clin Chim Acta 2005; 355: 105-11.        [ Links ]

102. Motohashi H, O’Connor, Katsuoka F, Engel JD, Yamamoto M. Integration and diversity of the regulatory network componed of Maf and CNC families of transcription factors. Gene 2002; 294: 1-12.        [ Links ]

103. Itoh K, Wakabayashi N, Katoh Y, Ishii T, Igarashi K, Engel JD, et al. Keap1 represses nuclear activation of antioxidant responsive elements by Nrf2 through binding to the amino-terminal Neh2 domain. Genes Dev 1999; 13: 76-86.        [ Links ]

104. Gong P, Cederbaum AI. Nrf2 is increased by CYP2E1 in rodent liver and HepG2 cells and protects against oxidative stress caused by CYP2E1. Hepatology 2006; 43: 144-53.        [ Links ]

105. Nguyen T, Yang CS, Pickett CB. The pathways and molecular mechanisms regulating Nrf2 activation in response to chemical stress. Free Radic Biol Med 2004; 37: 433-41.        [ Links ]

106. Xu Z, Chen L, Leung L, Yen TS, Lee C, Chan JY. Liver-specific inactivation of the Nrf1 gene in adult mouse leads to non-alcoholic steatohepatitis and hepatic neoplasia. Proc Natl Acad Sci USA 2005; 102: 4120-5.        [ Links ]

107. Younossi ZM, Baranova A, Ziegler K, Giacco L, Schlauch K, Born TL, et al. A genomic and proteomic study of the spectrum of nonalcoholic fatty liver disease. Hepatology 2005; 42: 665-74.        [ Links ]

108. Malassagne B, Ferret PJ, Hammoud R, Tullidez M, Bedda S, Trebeden H, et al. The superoxide dismutase mimetic MnTBAP prevents Fas-induced acute liver failure in the mouse. Gastroenterology 2001; 121: 1451-9.        [ Links ]

109. Ferret PJ, Hammoud R, Tulliez M, Tran A, Trebeden H, Jaffray P, et al. Detoxification of reactive oxygen species by a nonpeptidyl mimic of superoxide dismutase cures acetaminophen-induced acute liver failure in the mouse. Hepatology 2001; 33: 1173-80.        [ Links ]

110. García-Ruiz I, De la Torre P, Díaz T, Esteban E, Fernández I, Muñoz-Yagüe T, et al. Sp1 and Sp3 transcription factors mediate malondialdehyde-induced collagen α1(I) gene expression in cultured hepatic stellate cells. J Biol Chem 2002; 277: 30551-8.        [ Links ]

111. Esposito LA, Melov S, Panov A, Cottrell BA, Wallace DC. Mitochondrial disease in mouse results in increased oxidative stress. Proc Natl Acad Sci 1999; 96: 4820-25.        [ Links ]

112. Fromenty B, Robin MA, Igoudjil A, Mansouri A, Pessayre D. The ins and outs of mitochondrial dysfunction in NASH. Diabetes Metab 2004; 30: 121-38.        [ Links ]

113. Berson A, De Beco V, Lettéron P, Robin MA, Moreau C, Kahwaji J, et al. Steatohepatitis-inducing drugs cause mitochondrial dysfunction and lipid peroxidation in rat hepatocytes. Gastroenterology 1998; 114: 764-74.        [ Links ]

114. Fromenty B, Berson A, Pessayre D. Microvesicular steatosis and steatohepatitis: Role of mitochondrial dysfunction and lipid peroxidation. J Hepatol 1997; 26: 13-22.        [ Links ]

115. Caldwell SH, Swerdlow RH, Khan EM, Iezzoni JC, Hespenheide EE, Parks JK, et al. Mitochondrial abnormalities in non-alcoholic steatohepatitis. J Hepatol 1999; 31: 430-4.        [ Links ]

116. Zeviani M, Tiranti V, Piantadosi C. Mitochondrial disorders. Medicine 1998; 77: 59-72.        [ Links ]

117. Spahr L, Negro F, Leandro G, Marinescu O, Goodman KJ, Rubbia-Brandt L, et al. Impaired hepatic mitochondrial oxidation using the 13C-methionine breath test in patients with macrovesicular steatosis and patients with cirrhosis. Med Sci Monit 2003; 9: CR6-11.        [ Links ]

118. Cortez-Pinto H, Chatham J, Chacko VP, Arnold C, Rashid A, Diehl AM. Alterations in liver ATP homeostasis in human nonalcoholic steatohepatitis: a pilot study. JAMA 1999; 282: 1659-64.        [ Links ]

119. Morris A. Mitochondrial respiratory chain disorders and the liver. Liver 1999; 19: 357-68.        [ Links ]

120. Bowyer BA, Miles JM, Haymond MW, Fleming CR. L-carnitine therapy in home parenteral nutrition patients with abnormal liver tests and low plasma carnitine concentration. Gastroenterology 1988; 94: 434-8.        [ Links ]

121. Krähenbühl S, Mang G, Kupferschmidt H, Meier PJ, Krause M. Plasma and hepatic carnitine and coenzyme A pools in a patient with fatal, valproate induced hepatotoxicity. Gut 1995; 37: 140-3.        [ Links ]

122. Harper P, Wadström C, Backman L, Cederblad G. Increased liver carnitine content in obese women. Am J Clin Nutr 1995; 61: 18-25.        [ Links ]

123. Yamamoto S, Abe H, Kohgo T, Ogawa A, Ohtake A, Hayashibe H, et al. Two novel gene mutations (Glu 74Lys, Phe 383Tyr) causing the “hepatic” form of carnitine palmitoyltransferase II deficiency. Hum Genet 1996; 98: 116-8.        [ Links ]

124. Pérez-Cerreras M, Del Hoyo P, Martín MA, Rubio JC, Martínez A, Castellano G, et al. Defective hepatic mitochondrial respiratory chain in patients with nonalcoholic steatohepatitis. Hepatology 2003; 38: 999-1007.        [ Links ]

125. De Sousa C, Leung NWY, Chalmers RA, Peters TJ. Free and total carnitine and acylcarnitine content of plasma, urine, liver and muscle of alcoholics. Clin Sci 1988; 75: 437-40.        [ Links ]

126. Fromenty B, Pessayre D. Inhibition of mitochondrial beta-oxidation as a mechanism of hepatotoxicity. Pharmacol Ther 1995; 67: 101-54.        [ Links ]

127. Miele L, Grieco A, Armuzzi A, Candelli M, Forgione A, Gasbarrini A, et al. Hepatic mitochondrial beta-oxidation in patients with nonalcoholic steatohepatitis assessed by 13C-octanoate breath test. Am J Gastroenterol 2003; 98: 2335-6.        [ Links ]

128. Li Z, Peraldi P, Yang S, Lin H, Huang J, Watkins PA, et al. Probiotics and antibodies to TNF inhibit inflammatory activity and improve nonalcoholic fatty liver disease. Hepatology 2003; 37: 343-50.        [ Links ]

129. Brady LJ, Brady PS, Romsos DR, Hoppel CL. Elevated hepatic mitochondrial and peroxisomal oxidative capacities in fed and starved adult obese (ob/ob) mice. Biochem J 1985; 231: 439-44.        [ Links ]

130. Schoonjans K, Staels B, Auwerx J. The preroxisome proliferator activated receptors (PPARS) and their effects on lipid metabolism and adipocyte differentiation. Biochim Biophys Acta 1996; 1302: 93-109.        [ Links ]

131. Kersten S, Seydoux J, Peters JM, González FJ, Desvergne B, Wahli W. Peroxisome proliferator-activated receptor-α mediates the adoptive response to fasting. J Clin Invest 1999; 103: 1489-98.        [ Links ]

132. Fromenty B, Pessayre D. Mitochondrial injury and NASH. In: Farrell GC, George J, de la M. Hall P, McCullough AJ. Eds Fatty Liver Disease. NASH and related disorders. Blackwell Publ Ltd Malden 132-42.        [ Links ]

133. Wallace DC. Mitochondrial disease in man and mouse. Science 1999; 283: 1482-8.        [ Links ]

134. Halliwell B. Free radicals, antioxidants, and human disease: curiosity, cause, or consequence? Lancet 1994; 344: 721-4.        [ Links ]

135. Haque M, Mirshahi F, Campbell-Sargent C, Sterling RK, Luketic VA, Shiffman ML, et al. Nonalcoholic steatohepatitis (NASH) is associated with hepatocyte mitochondrial depletion. Hepatology 2002; 36: 430A.        [ Links ]

136. Farell GC. Animal Models of steatohepatitis. In: Farell GC, George J, de la M Hall P, McCullough AJ, editors. Fatty liver disease. NASH and related disorders. Blackwell Publ Ltd Malden 2005: 91-108.        [ Links ]

137. García-Ruiz I, Rodríguez-Juan C, Díaz-Sanjuan T, Del Hoyo P, Colina F, Muñoz-Yagüe T, et al. Uric acid and anti-TNFα antibody improve mitochondrial respiratory chain dysfunction In ob/ob mice. Hepatology 2006; 44: 581-91.        [ Links ]

138. Paradies G, Petrosillo G, Pistolese M, Ruggiero FM. The effect of reactive oxygen species generated from the mitochondrial electron transport chain on the cytochrome c oxidase activity and on the cardiolipin content in bovine heart submitochondrial particles. FEBS Lett 2000; 466: 323-6.        [ Links ]

139. Leclerq IA, Farell GC, Field J, Bell DR, Gonzalez FJ, et al. CYP4A as microsomal catalysts of lipid peroxides in murine non-alcoholic steatohepatitis. J Clin Invest 2000; 105: 1067-75.        [ Links ]

140. Letteron P, Fromenty B, Terris B, Degott C, Pessayre D. Acute and chronic hepatic steatosis lead to in vivo lipid peroxidation in mice. J Hepatol 1996; 24: 200-8.        [ Links ]

141. Seke S, Kitada T, Yamada T, Sakaguchi H, Nakatani K, Wakasa K. In situ detection of lipid peroxidation and oxidative DNA damage in non alcoholic fatty liver disease. J Hepatol 2002; 37: 56-62.        [ Links ]

142. Chen J, Petersen DR, Schenker S, Henderson GI. Formation of malondialdehyde adducts in livers of rats exposed to ethanol: Role in ethanol-mediated inhibition of cytochrome c oxidase. Alcohol Clin Exp Res 2000; 24: 544-52.        [ Links ]

143. Chen J, Schenker S, Frosto TA, Hensderson GI. Inhibition of cytochrome c oxidase activity by 4-hydroxynonenal (HNE): Role of HNE adduct formation with the enzyme catalytic site. Biochem Biophys Acta 1998; 1380: 336-44.        [ Links ]

144. Hruszkewycz AM. Evidence for mitochondrial DNA damage by lipid peroxidation. Biochem Biophys Res Común 1988; 153: 191-7.        [ Links ]

145. Cadet J, Delatour T, Douki T, Gasparutto D, Pouget JP, Ravanat JL, et al. Hydroxyl radicals and DNA base damage. Mutat Res 1999; 424: 9-21.        [ Links ]

146. Demeilliers C, Maisonneuve C, Grodet A, Mansouri A, Nguyen R, Tinel M, et al. Impaired adaptive resynthesis and prolonged depletion of hepatic mitochondrial DNA after repeated alcohol binges in mice. Gastroenterology 2002 ; 123: 1278-90.        [ Links ]

147. Croteau DL, Stierum RH, Bohr VA. Mitochondrial DNA repair pathways. Mutat Res 1999; 434: 137-48.        [ Links ]

148. Ide T, Tsutsui H, Hayashidani S, Kang D, Suematsu N, Nakamura K, et al. Mitochondrial DNA damage and dysfunction associated with oxidative stress in failing hearts after myocardial infarction. Cir Res 2001; 88: 529-35.        [ Links ]

149. Patel M, Day BJ. Metalloporphyrin class of therapeutic catalytic antioxidants. Trends Pharmacol Sci 1999; 20: 359-64.        [ Links ]

150. Crespo J, Cayón A, Fernández-Gil P, Hernández-Guerra M, Mayorga M, Domínguez-Díaz A, et al. Gene expression of tumor necrosis factor a and TNF-receptors, p55 and p75, in nonalcoholic steatohepatitis patients. Hepatology 2001; 34: 1158-63.        [ Links ]

151. Tilg H, Diehl AM. Cytokines in alcoholic and nonalcoholic steatohepatitis. N Engl J Med 2000; 343: 1467-76.        [ Links ]

152. Kugelmas M, Hill DB, Vivian B, Marsano L, McClain CJ. Cytokines and NASH: A pilot study of the effects of lifestyle modification and vitamin E. Hepatology 2003; 38: 413-9.        [ Links ]

153. Hui JM, Hodge A, Farrel, GC, Kench JG, Kriketos A, George J. Beyond insulin resistance in NASH: TNFα or adiponectin? Hepatology 2004; 40: 46-54.        [ Links ]

154. Hotamisligil GS, Arner P, Caro JF, Atkinson RL, Spiegelman BM. Increased adipose tissue expression of tumor necrosis factor-alpha in human obesity and insulin resistance. J Clin Invest 1995; 95: 2409-15.        [ Links ]

155. Miyazaki Y, Pipek R, Mandarino LJ, DeFronzo RA. Tumor necrosis factor alpha and insulin resistance in obese type 2 diabetic patients. Int J Obes Relat Metab Disord 2003; 27: 88-94.        [ Links ]

156. Sánchez-Alcázar JA, Schneider E, Hernández-Muñoz I, Ruiz-Cabellos J, Siles-Rivas E, de la Torre P, et al. Reactive oxygen species mediates the down-regulation of mitochondrial transcripts and proteins by tumour necrosis factor-α in L929 cells. Biochem J 2003; 370: 609-19.        [ Links ]

157. Sanyal AJ. The pathogenesis of NASH: Human studies. In: Fatty Liver Disease. NASH and related disorders. Farrell GC, George J, Hall P de la M, McCullough AJ, editors. Blackwell Publ Ltd Malden 2005: 76-90.        [ Links ]

158. Kern PA, Saghizadeh M, Org JM, Bosch RJ, Deem R, Simsolo RB. The expression of tumor necrosis factor in human adipose tissue. Regulation by obesity, weight loss, and relationship to lipoprotein lipase. J Clin Invest 1995; 95: 2111-9.        [ Links ]

159. Weisberg SP, McCann D, Desai M, Rosenbaum M, Leibel RL, Ferrante AW Jr. Obesity is associated with macrophage accumulation in adipose tissue. J Clin Invest 2003; 112: 1796-808.        [ Links ]

160. Bouloumie A, Curat CA, Sengenes C, Lolmede K, Miranville A, Busse R. Role of macrophage tissue infiltration in metabolic diseases. Curr Opin Clin Nutr Metab Care 2005; 8: 346-54.        [ Links ]

161. Wellen KE, Hotamisligil GS. Obesity-induced inflammatory changes in adipose tissue. J Clin Invest 2003; 112: 1785-8.        [ Links ]

162. Angulo P. NAFLD, obesity, and bariatic surgery. Gastroenterology 2006; 130: 1848-52.        [ Links ]

163. Nguyen MTA, Satoh H, Favelyukis S, Babendure JL, Imamura T, Sbodio JI, et al. JNK and tumor necrosis factor-α mediate free fatty acid-induced insulin resistance in 3T3-L1 adipocytes. J Biol Chem 2005; 280: 35361-71.        [ Links ]

164. Feldstein AE, Werneburg NW, Canbay A, Guicciardi ME, Bronk SF, Rydzewski R, et al. Free fatty acids promote hepatic lipotoxicity by stimulating TNFα expression via a lysosomal pathway. Hepatology 2004; 40: 185-94.        [ Links ]

165. Cai D, Yuan M, Frantz D, Melendez PA, Hansen L, Lee J, et al. Local and systemic insulin resistance resulting from hepatic activation of IKK-beta and NF kappa B. Nat Med 2005; 11: 183-90.        [ Links ]

166. Arkan MC. Hevener AL, Greten FR, Maeda S, Li Z-W, Lond JM, et al. IKK-β links inflammation to obesity-induced insulin resistance. Nat Med 2005; 11: 191-8.        [ Links ]

167. Maeda N, Shimomura I, Kishida K, Nishizawa H, Matsuda M, Nagaretani H, et al. Diet-induced insulin resistance in mice lacking adiponectin/ACRP30. Nat Med 2002; 8: 731-7.        [ Links ]

168. Xu A, Wang Y, Keshaw H, Xu LY, Lam KS, Cooper GJ. The fatderived hormona adiponectin alleviate alcoholic and nonalcoholic fatty liver diseases in mice. J Clin Invest 2003; 112: 91-100.        [ Links ]

169. Kamada Y, Tamura S, Kiso S, Matsumoto H, Saji Y, Yoshida Y, et al. Enhanced carbon tetrachloride-induced liver fibrosis in mice lacking adiponectin. Gastroenterology 2003; 125: 1796-807.        [ Links ]

170. Lopez-Bermejo A, Botas P, Funahashi T, Delgado E, Kihara S, Ricart W, et al. Adiponectin, hepatocellular dysfunction and insulin sensitivity. Clin Endocrinol (Oxf) 2004; 60: 256-63.        [ Links ]

171. Ding X, Saxena NK, Lin S, Xu A, Srinivasan S, Anania FA. The roles of leptin and adiponectin: a novel paradigm in adipocytokine regulation of liver fibrosis and stellate cell biology. Am J Pathol 2005; 166: 1655-69.        [ Links ]

172. Masaki T, Chiba S, Tatsukawa H, Yasuda T, Noguchi H, Seike M, et al. Adiponectin protects LPS-induced liver injury through modulation of TNF-α in KK-Ay obese mice. Hepatology 2004; 40: 177-84.        [ Links ]

173. Ouchi N, Kihara S, Arita Y, Okamoto Y, Maeda K, Kuriyama H, et al. Adiponectin, an adipocyte-derived plasma protein, inhibits endothelial NF-kappaB signaling through a cAMP-dependent pathway. Circulation 2000; 102: 1296-301.        [ Links ]

174. Yokota T, Oritani K, Takahashi I, Ishikawa J, Matsuyama A, Ouchi N, et al. Adiponectin, a new member of the family of soluble defense collagens, negatively regulates the growth of myelomonocytic progenitors and the functions of macrophages. Blood 2000; 96: 1723-32.        [ Links ]

175. Yamauchi T, Kamon J, Kaki H, Terauchi Y, Kubota N, Hara K et al. The fat-derived hormone adiponectin reverses insulin resistance associated with both lipoatrophy and obesity. Nat Med 2001; 7: 887-8.        [ Links ]

176. Yamauchi T, Kamon J, Minokoshi Y, Ito Y, Kaki H, Uchida S, et al. Adiponectin stimulates glucosa utilization and fatty-acid oxidation by activating AMP-activated protein kinase. Nat Med 2002; 8:1288-95.        [ Links ]

177. Chen MB, McAinch AJ, Macaulay SL, Castelli LA, O’Brien PE, Dixon JB, et al. Impaired activation of AMP-kinase and fatty acid oxidation by globular adiponectin in cultured human skeletal muscle from obese type 2 diabetics. J Clin Endocrin Metab 2005; 90: 3665-72.        [ Links ]

178. Berg AH, Combs TP, Scherer PE. ACRP30/adiponectin: an adipokine regulating glucosa and lipid metabolism. Trenes Endocrin Metab 2002; 13: 84-9.        [ Links ]

179. Bouskila M, Pajvani UB, Scherer PE. Adiponectin: a relevant placer in PPARγ-agonist-mediated improvements in hepatic insulin sensitivity? Int J Obes Relat Metab Disord 2005; 29 (Supl. 1): S17-S23.        [ Links ]

180. Pagano C, Soardo G, Esposito W, Fallo F, Basan L, Donnini D et al. Plasma adiponectin is decreased in nonalcoholic fatty liver disease. Eur J Endocrinol 2005; 152: 113-8.        [ Links ]

181. Vuppalanchi R, Marri S, Kolwankar D, Considine RV, Chalasani N. Is adiponectin involved in the pathogenesis of nonalcoholic steatohepatitis? A preliminary human study. J Clin Gastroenterol 2005;39: 237-42.        [ Links ]

182. Havel PJ. Update on adipocyte hormones: regulation of energy balance and carbohydrate/lipid metaboism. Diabetes 2004; 53(Suppl 1): S143-S151.        [ Links ]

183. Westerbacka J, Corner A, Tiikkainen M, Vehkavaara S, Hakkinen AM, et al. Women and men have similar amounts of liver and intraabdominal fat, despite more subcutaneous fat in women: Implications for sex differences in markers of cardiovascular risk. Diabetologia 2004; 47: 1360-9.        [ Links ]

184. Bajaj M, Suraamornkul S, Piper P, Hardies LJ, Glass L, Cersosimo E, et al. Decreased plasma adiponectin concentrations are closely related to hepatic fat content and hepatic insulin resistance in pioglitazone-treated type 2 diabetic patients. J Clin Endicrinol Metab 2004;89: 200-6.        [ Links ]

185. Sánchez-Alcázar JA, Schneider E, Martínez MA, Carmona P, Hernández-Muñoz I, Siles E, et al. Tumor necrosis factor-α increases the steady state reduction of cytochrome b of the mitochondrial respiratory chain in metabolically inhibited L929 cells. J Biol Chem 2000; 275: 13353-61.        [ Links ]

186. Higuchi M, Proske RJ, Yeh ET. Inhibition of mitochondrial respiratory chain complex I by TNF results in cytochrome c release, membrane permeability transition, and apoptosis. Oncogene 1998 ; 17: 2515-24.        [ Links ]

187. Yang S, Zhu H, Li Y, Lin H, Gabrielson K, Trush MA, et al. Mitochondrial adaptations to obesity-related oxidant stress. Arch Biochem Biophys 2000; 378: 259-68.        [ Links ]

188. Cohen P, Miyazaki M, Socci ND, Hagge-Greenberg A, Liedtke W, Soukas AA, et al. Role for stearoyl –CoA desaturase-1 in leptin-mediated weight loss. Science 2002; 297: 240-3.        [ Links ]

189. Tracey KJ, Cerami A. Tumor necrosis factor a pleitropic cytokine and therapeutic target. Annu Rev Med 1994; 45: 491-503.        [ Links ]

190. Geller DA , Nussler AK, Di Silvio M, Lowenstein CJ, Shapiro RA, Wang SC, et al. Cytokines, endotoxin, and glucocorticoides regulate the expresión of inducible nitric oxide synthetase in hepatocytes. Proc Natl Acad Sci USA 1993; 90: 522-6.        [ Links ]

191. Curran RB, Billiar TR, Stuehr DJ, Hoffmann K, Simmons RL. Hepatocytes produce nitrogen oxides from L-arginine in response to inflammatory products of Kupffer cells. J Exp Med 1989; 170:1769-74.        [ Links ]

192. Hatano E, Bennett BL, Manning AM, Qian T, Lemasters JJ, Brenner DA. NF-κB stimulates inducible nitric oxide synthase to protect mouse hepatocytes from TNFα- and Fas-mediated apoptosis. Gastroenterology 2001: 120: 1251-62.        [ Links ]

193. Radi R, Cassina A, Hodara R, Castro L. Peroxynitrite reactions and formation in mitochondria. Free Radi Biol Med 2002; 33: 1451-64.        [ Links ]

194. Brown GC, Cooper CE. Nanomolar concentrations of NO reversibly inhibit sypnaptosomal respiration by competing with oxygen at cytochrome oxidase. FEBS. Lett 1994; 356: 295-8.        [ Links ]

195. Radi R, Cassina A, Hodara R, Castro L. Peroxynitrite reactions and formation in mitochondria. Free Radi Biol Med 2002; 33: 1451-64.        [ Links ]

196. Radi R, Cassina A, Hodara R. Nitric oxide and peroxynitrite interactions with mitochondria. Biol Chem 2002; 383: 401-9.        [ Links ]

197. Castro L, Eiserich JP, Sweeney S, Radi R, Freeman BA. Cytochrome c: a catalyst and target of nitrite-hydrogen peroxide-dependent protein nitration. Arch Biochem Biophys 2004; 421: 99-107.        [ Links ]

198. Murria J, Taylor SW, Zhang B, Ghosh SS, Capaldi RA. Oxidative damage to mitochondrial complex I due to peroxynitrite. J Biol Chem 2003; 278: 37223-30.        [ Links ]

199. Guidarelli A, Fiorani M, Cantoni O. Enhancing effects of intracellular ascorbic acid on peroxynitrite-induced U937 cell death are mediated by mitochondrial events resulting in enhanced sensitivity to peroxynitrite-dependent inhibition of complex III and formation of hydrogen peroxide. Biochem J 2004; 378: 959-66.        [ Links ]

200. Radi R, Beckman JS, Bush KM, Freeman BA. Peroxynitrite oxidation of sulfhydryls: the cytotoxic potential of superoxide and nitric oxide. J Biol Chem 1991; 266: 4244-50.        [ Links ]

201. Szabó C. DNA strand breakage and activation of poly-ADP ribosyltransferase: a cytotoxic pathway triggered by ONOO. Free Rad Biol Med 1996; 21: 855-69.        [ Links ]

202. Viner RI, Williams TD, Schoneich C. Peroxynitrite modification of protein thiols: oxidation, nitrosylation, and S-glutathiolation of functionally important cysteine residue(s) in the sarcoplasmic reticulum Ca-ATPase. Biochemistry 1999; 38: 12408-15.        [ Links ]

203. Hooper DC, Bagasra O, Marini JC, Zborek A, Ohnishi ST, Kean R, et al. Prevention of experimental allergic encephalomyelitis by targeting nitric oxide and peroxynitrite: implications for the treatment of multiple sclerosis. Proc Natl Acad Sci USA 1997; 94: 2528-33.        [ Links ]

204. MacMillan-Crow LA, Crow JP, Thompson JA. Peroxynitrite-mediated inactivation of manganese superoxide dismutase involves nitration and oxidation of critical tyrosine residues. Biochemistry 1998; 37: 1613-22.        [ Links ]

205. Whiteman M, Ketsawatsakul U, Halliwell B. A reassessment of the peroxynitrite scavenging activity of uric acid. Ann NY Acad Sci 2002; 242-59.        [ Links ]

206. Kuzkaya N, Weissmann N, Harrison DG, Dikalov S. Interactions of peroxynitrite with uric acid in the presence of ascorbate and thiols:implications for uncoupling endothelial nitric oxide synthase. Biochem Pharm 2005; 70: 343-54.        [ Links ]

207. Chou SM, Wang HS, Taniguch, A. Role of SOD-1 and nitric oxide/cyclic GMP cascade on neurofilament aggregation in ALS/MND. J Neurol Sci 1996; 139 (Supl.): 16-26.        [ Links ]

208. Hooper DC, Scott GS, Zborek A, Mikheeva T, Kean RB, Koprowski H, et al. Uric acid, a peroxynitrite scavenger, inhibits CNS inflammation, blood-CNS barrier permeability changes, and tissue damage in a mouse model of multiple sclerosis. FASEB J 2000; 14:691-8.        [ Links ]

209. Weltman MD, Farell GC, Hall P, Ingelman-Sundberg M, Liddle C. Hepatic cytochrome P450 2E1 is increased in patients with non-alcoholic steatohepatitis. Hepatology 1998; 27: 128-33.        [ Links ]

210. O’Shea D, Davis SN, Kim RB, Wilkinson GR. Effect of fasting and obesity in human son the 6-hydroxylation of chlorzoxazone: a putative probe of CYP2E1 activity. Clin Pharmacol Ther 1994; 56: 359-67.        [ Links ]

211. Wang Z, Hall SD, Maya JF, Li I, Asghar A, Gorsky JC. Diabetes mellitus increases the in vivo activity of cytochrome P4502E1 in humans. Br J Clin Pharmacol 2003; 55: 77-85.        [ Links ]

212. Chalasani N, Gorski JC, Asghar MS, Asghar A, Foresman B, Hall SD, et al. Hepatic cytochrome P450 2E1 activity in non-diabetic patients with non-alcoholic steatohepatitis . Hepatology 2003; 37: 544-50.        [ Links ]

213. Emery MG, Fisher JM, Chein JY, Kharasch ED, Delling EP, Kowdley, et al. CYP2E1 activity befote and after weight loss in morbidly obese subjects with non-alcoholic fatty liver disease. Hepatology 2003; 38: 428-35.        [ Links ]

214. Gonzalez FJ. Role of cytochromes P450 in chemical toxicity and oxidative stress: studies with CYP2E1. Mutat Res 2005; 569: 101-10.        [ Links ]

215. Amet Y, Berthou F, Goasduff T, Salaun JP, Le Breton L, Menez JF. Evidence that cytochrome p450 2E1 is envolved in the (ω-1)-hydroxylation of lauric acid in rat liver microsomas. Biochem Biophys Res Commun 1994; 203: 1168-74.        [ Links ]

216. Leclercq IA, Farrell GC, Field J, Bell DR, González FJ, Robertson GR. CYP2E1 and CYP4A as microsomal catalysts of lipid peroxides in murine non-alcoholic steatohepatitis. J Clin Invest 2000; 105: 1067-75.        [ Links ]

217. Schattenberg JM, Wang Y, Singh R, Rigoli RM, Czaja MJ. Hepatocyte CYP2E1 overexpression and steatohepatitis lead to impaired hepatic insulin signaling. J Biol Chem 2005; 280: 9887-94.        [ Links ]

218. Kono H, Rusyn I, Yin M, Gabela E, Yamashina S, Dickalova A. NADPH-oxidase-derived free radicals are key oxidants in alcoholinduced liver disease. J Clin Invest 2000; 106: 867-72.        [ Links ]

219. Yang SQ, Lin HZ, Lane MD, Clemens M, Diehl AM. Obesity increases sensitivity to endotoxin liver injury: Implications for the pathogenesis of steatohepatitis. Proc Natl Acad Sci USA. 1997; 94: 2557-62.        [ Links ]

220. Wigg AJ, Roberts-Thomson IC, Dymock RB, McCarthy PJ, Grose RH, Cummins AG. The role of small intestinal bacterial overgrowth, intestinal permeability, endotoxemia, and tumor necrosis factor alpha in the patogenesis of non-alcoholic steatohepatitis. Gut 2001; 48: 206-11.        [ Links ]

221. Hegner D, Platt D. Effect of essential phospholipids on the properties of ATPases of isolated rat liver plasma membranas of young and old animals. Mech Ageing Dev 1975; 4: 191-200.        [ Links ]

222. Neuberger J, Hegarty JE. Eddleston ALWF, Williams R. Effect of polyunsaturated phosphatidylcholine on immune-mediated hepatocyte damage. Gut 1983; 24: 751-5.        [ Links ]

223. Jenkins PJ, Portman BP, Eddleston ALWF, Williams R. Use of polyunsaturated phosphatidylcholine in HBsAg negative chronic active hepatitis. Results of a prospective double blind controlled trial. Liver 1982; 2: 77-81.        [ Links ]

224. Masumoto N, Tasaka K, Miyake A, Tanizawa O. Superoxide anion increases intracellular free calcium in human myometrial cell. J Biol Chem 1990; 265: 225-336.        [ Links ]

225. Solís-Herruzo JA, De La Torre P, Muñoz-Yagüe MT. Hepatic stellate cells: Architects of hepatic fibrosis. Rev Esp Enferm Dig 2003;95: 438-9.        [ Links ]

226. Solís Herruzo JA, García Ruiz I, De La Torre P, Díaz San Juan T, Muñoz-Yagüe MT. Cytokine networks involved in liver extracellular matrix remodelling in fibrogenesis. In: Moreno-Otero R, Albillos A, García-Monzón C. Immunology and The Liver: Cytokines. Madrid: Acción Médica; 2001.        [ Links ]

227. Solís Herruzo JA. Factores Involucrados en la fibrogénesis hepática. Gastroenterología Hepatología 2000; 23: 186-99.        [ Links ]

228. Cortez-Pinto H, Batista A, Camilo ME, de Moura MV. Hepatic stellate cell activation occurs in non-alcoholic steatohepatitis. Hepatogastroenterology 2001; 48: 87-90.        [ Links ]

229. Washington K, Wright K, Shyr Y, Hunter EB, Olson S, Raiford DS.Hepatic stellate cell activation in non-alcoholic steatohepatitis and fatty liver. Hum Pathol 2000; 31: 822-88.        [ Links ]

230. George J, Pera N, Phung N, Leclercq I,Yung-Hou J, Farrell G. Lipid peroxidation, stellate cell activation and hepatic fibrogénesis in a rat model of chronic steatohepatitis. J Hepatol 2003; 39: 756-64 .        [ Links ]

231. Barnes PJ, Karin M. Nuclear factor-κB: A pivotal transcrition factor in chronic inflammatory diseases. N Engl J Med 1997; 336: 1066-71.        [ Links ]

232. Lee KS, Buch M, Houglum K, Chojkier M. Activation of hepatic stellate cells by TGF alpha and collagen type I is mediated by oxidative stress through c-myb expression. J Clin Invest 1995; 96: 2461-8.        [ Links ]

233. Lee KS, Buch M, Houglum K, Chojkier M. Activation of hepatic stellate cells by TGF alpha and collagen type I is mediated by oxidative stress through c-myb expression. J Clin Invest 1995; 96: 2461-8.        [ Links ]

234. Canboy A, Taimr P, Torok N, Friedman S, Gores GJ. Apoptotic body engulfment by human stellate cell line is profibrogenic. Lab Invest 2003; 83: 655-63.        [ Links ]

235. Chojkier M, Houglum K. Solis-Herruzo J, Brenner, DA. Stimulation of collagen gene expression by ascorbic acid in cultured human fibroblasts. A role for lipid peroxidation? J Biol Chem 1989; 264:16957-62.        [ Links ]

236. Maher JJ, Tzagarakis C, Giménez A. Malondialdehyde stimulates-collagen production by hepatic lipocytes only upon activation in primary culture. Alcohol Alcohol 1994; 29: 605-10.        [ Links ]

237. Zamara E, Novo E, Marra F, Gentilini A, Romanelli RG, Caligiuri A, et al. 4-Hydroxynonenal as a selective profibrogenic stimulus for activated human hepatic stellate cells. J Hepatol 2004; 40: 60-8.        [ Links ]

238. Parola M, Pinzani M, Casini A, Albano E, Poli G, Gentilini A, et al. Stimulation of lipid peroxidation or 4-hydroxynonenal treatment increases procollagen alpha 1 (I) gene expression in human liver fatstoring cells. Biochem Biophys Res Comm 1993; 194: 1044-50.        [ Links ]

239. Parola M, Pinzani M, Casini A, Leonarduzzi G, Marra F, Caligiuri A, et al. Induction of procollagen type I gene expression and synthesis in human hepatic stellate cells by 4-hydroxy-2,3-nonenal and other 4-hydroxy-2,3-alkenals is related to their molecular structure. Biochem Biophys Res Comm 1996; 222: 261-4.        [ Links ]

240. Tsukamoto H. Oxidative stress, antioxidants, and alcoholic liver fibrogenesis. Alcohol 1993; 10: 465-7.        [ Links ]

241. Tsukamoto H, Rippe RA, Niemela O, Lin M. Roles of oxidative stress in activation of Kupffer and Ito cells in liver fibrogenesis. J Gastroenterol Hepatol 1995; 10 (Supl. 1): S50-S53.        [ Links ]

242. Esterbauer H, Schaur RJ, Zollner H. Chemistry and biochemistry of 4-hydroxynonenal, malonaldehyde and related aldehydes. Free Rad Biol Med 1991; 11: 81-128.        [ Links ]

243. Houglum K, Venkataraman A, Lyche K, Chojkier M. A pilot study of the effects of d-alpha-tocopherol on hepatic stellate cell activation in chronic hepatitis C. Gastroenterology 1997; 113: 1069-73.        [ Links ]

244. Tsukamoto H, Horne W, Kamimura S, Niemela O, Parkkila S, Yla-Herttuala S, et al. Experimental liver cirrhosis induced by alcohol and iron. J Clin Invest 1995; 96: 620-30.        [ Links ]

245. Bedossa P, Houglum K, Trautwein Ch, Holstege A, Chojkier M. Stimulation of collagen alpha 1(I) gene expression is associated with lipid peroxidation in hepatocellular injury: a link to tissue fibrosis? Hepatology 1994; 19: 1262-71.        [ Links ]

246. Parola M, Leonarduzzi G, Biasi F, Albano E, Bicoca ME, Poli G, et al. Vitamin E dietary supplementation protects against carbon tetrachloride-induced chronic liver damage and cirrhosis. Hepatology 1992; 16: 1014-21.        [ Links ]

247. Houglum K, Filip M, Witztum JL, Chojkier M. Malondialdehyde and 4-hydroxynonenal protein adducts in plasma and liver of rats with iron overload. J Clin Invest 1990; 86: 1991-8.        [ Links ]

248. Pietrangelo A, Gualdi R, Casalgrandi G, Montosi G, Venture E. Molecular and cellular aspects of iron-induced hepatic cirrhosis in rodents. J Clin Invest 1995; 95: 1824-31.        [ Links ]

249. García Ruiz I, De La Torre MP, Díaz T, Esteban E, Morillas JD, Muñoz-Yagüe MT, et al. Sp family of transcription factors is involved in iron-induced collagen α1(I) gene expression. DNA Cell Biology 2000; 19: 167-78.        [ Links ]

250. Jian J-G, Chen Q, Bell A, Zarnegar R. Transcriptional regulation of the hepatocyte growth factor (HGF) gene by the Sp family of transcription factors. Oncogene 1997; 14: 3039-49.        [ Links ]

251. Ihn H, Trojanowska M. Sp3 is a transcriptional activator of the human alpha2(I) collagen gene. Nucleic Acid Res 1997; 25: 3712-7.        [ Links ]

252. Ihn H, Leroy EC, Trojanowska M. Oncostatin M stimulates transcription of the human alpha2(I) collagen gene via the Sp1/Sp3-binding site. J Biol Chem 1997; 272: 24666-72.        [ Links ]

253. Chen S, Artlett CM, Jimenez SA, Varga J. Modulation of human alpha1(I) procollagen gene activity by interaction with Sp1 and Sp3 transcription factors in vitro. Gene 1998 ; 215: 101-10.        [ Links ]

254. Rippe RA, Almounajed G, Brenner DA. Sp1 binding activity increases in activated Ito cells. Hepatology 1995; 22: 241-51.        [ Links ]

255. Angulo P, Alba LM, Petrovic LM, Adams LA, Lindo KD, Jensen MD. Leptin, insulin resistance and liver fibrosis in human non alcoholic fatty liver disease. J Hepatol 2004; 41: 943-9.        [ Links ]

256. Zhang Y, Proenca R, Maffei M, Barone M, Leopond L, Friedman JM. Positional cloning of the mouse obese gene and its human homologue. Nature 1994; 372: 425-32.        [ Links ]

257. Friedman JM. Leptin, leptin receptors, and the control of body weight. Nutr Rev 1998; 56: S38-S46.        [ Links ]

258. Grunfeld C, Zhao C, Fuller J, Pollack A, Moser A, Friedman J, et al. Endotoxin and cytokine induce expression of leptin, the OB gene product, in hamster. A role for leptin in the anorexia of infection. J Clin Invest 1996; 97: 2152-7.        [ Links ]

259. Saxena NK, Ikeda K, Rockey DC, Friedman SL, Anania FA. Leptin in hepatic fibrosis: evidence for increased collagen production in stellate cells and lean littermate of ob/ob mice. Hepatology 2002; 35: 762-71.        [ Links ]

260. Leclercq IA, Farell GC, Schriemer R, Robertson GR. Leptin is essential for hepatic fibrogenic response to chronic liver injury. J Hepatol 2002; 37: 206-13.        [ Links ]

261. Ikejima K, Takei Y, Honda H, Hirose M, Yoshikawa M, Zhang YJ. Leptin receptor-mediated signaling regulates hepatic fibrogenesis and remodeling of extracellular matriz in the rat. Gastroenterology 2002; 122: 1399-410.        [ Links ]

262. Ikejima K, Honda H, Yoshikawa M, Hirose M, Kitamura T, Takei Y, et al. Leptin augments inflammatory and profibrogenic responses in the murine liver induced by hepatotoxic chemicals. Hepatology 2001; 34: 288-97.        [ Links ]

263. Piche T, Gelsi E, Schneider SM, Hebuterne X, Giudicelli J, Ferrua B, et al. Fatigue is associated with high circulating leptin levels in chronic hepatitis C. Gut 2002; 51: 434-9.        [ Links ]

264. Testa R, Franceschini R, Giannini E, Cataldi A, Botta F, Fasoli A, et al. Serum leptin levels in patients with viral chronic hepatitis or liver cirrhosis. J Hepatol 2000; 33: 33-7.        [ Links ]

265. McCullough AJ, Bugianesi E, Marchesini G, Kalham SC. Gender-dependent alterations in serum leptin in alcoholic cirrhosis. Gastroenterology 1998; 115: 947-53.        [ Links ]

266. Piche T, Vandenlos S, Abakar-Mahamet A, Vanbierliet G, Barjoan EM, Calle G, et al. The severity of liver fibrosis is associated with high leptin levels in chronic hepatitis C. J Viral Hep. 2004; 11: 91-6.        [ Links ]

267. Cao Q, Mak KM, Lieber CS. Leptin enhances α1(I) collagen gene expression in LX-2 human hepatic stellate cells through JAK-mediated H2O2-dependent MAPK pathways. J Cell Biochem 2006; 97: 188-97.        [ Links ]

268. Tang M, Potter JJ, Mezey E. leptin enhances the effect of transforming growth factor beta in increasing type I collagen formation. Biochem Biophys Res Commun 2002; 297: 906-11.        [ Links ]

269. Cao Q, Mak KM, Ren C, Lieber CS. Leptin stimulates tissue inhibitor of metalloproteinase-1 in human hepatic stellate cells. J Biol Chem 2004; 279: 4292-304.        [ Links ]

270. Ikejima K, Okumura K, Lang T, Honda H, Abe W, Yamashina S, et al. The role of leptin in progresión of non-alcoholic fatty liver disease. Hepatol Res 2005; 33: 151-4.        [ Links ]

271. Saxena NK, Titus MA, Ding X, Floyd J, Srinivasan S, Sitaraman SV, et al. Leptin as a novel profibrogenic cytokine in hepatic stellate cells: mitogenesis and inhibition of apoptosis mediated by extracellular regulated kinase (Erk) and Akt phosphorylation FASEB J 2004; 181: 1612-4.        [ Links ]

272. Bouloumie A, Marumo T, Lafontan M, Busse R. Leptin induces oxidative stress in human endotelial cells. Fed Am Soc Exp Biol J 1999; 13: 1231-8.        [ Links ]

273. Yamagishi S, Edelstein D, Du X, Kaneda Y, Guzman M, Brownlee M. Leptin induces mitochondrial superoxide production and monocyte chemoattractant protein-1 expression in aortic endotelial cells by increasing fatty acid oxidation via protein kinase A. J Biol Chem. 2001; 276 (27):25096-100.        [ Links ]

274. Bataller R, Schwabe RF, Choi YH, Yang L, Palk YH, Lindquist J, et al. NADPH oxidase signal transduces angiotensin II in hepatic stellate cells and is critical in hepatic fibrosis. J Clin Invest 2003; 112:1383-94.        [ Links ]

275. Oben JA, Roskams T, Yang S, Lin H, Sinelli N, Li Z, et al. Norepinephrine induces hepatic fibrogenesis in leptin deficient ob/ob mice.Biochem Biophys Res Commun 2003; 308: 284-92.        [ Links ]

276. Sahai A, Malladi P, Melón-Aldana H, Green RM, Whitington PF. Upregulation of osteopontin expression is envolved in the development of non alcoholic steatohepatitis in a dietary murine model. Am J Physiol Gastrointest Liver Physiol 2004; 287: 264-73.        [ Links ]

277. Marceau P, Biron S, Hould FS, Marceau S, Simard S, Thung NS, et al. Liver pathology and metabolic syndrome X in severe obesity. J Clin Endocrinol Metab 1999; 84: 1513-7.        [ Links ]

278. Mezey E. Dietary fat and alcoholic liver disease. Hepatology 1998;28: 901-5.        [ Links ]

279. Monto A, Alonzo J, Watson JJ, Grunfeld C, Wright TL. Steatosis in chronic hepatitis C: relative contributions of obesity, diabetes mellitus, and alcohol. Hepatology 2002; 36: 729-36.        [ Links ]

280. Dixon JB, Bhathai PS, O’Brian PE. Nonalcoholic fatty liver disease: predictors of nonalcoholic steatohepatitis and liver fibrosis in the severely obese. Gastroenterology 2001; 121: 91-100.        [ Links ]

281. Hickman IJ, Powell EE, Prins JB, Clouston AD, Ash S, Purdie DM, et al. In overweight patients with chronic hepatitis C, circulating insulin is associated with hepatic fibrosis: implications for therapy. J Hepatol 2003; 39: 1042-8.        [ Links ]

282. Hui JM, Sud A, Farrell GC, Bandara P, Byth K, Kench JG, et al. Insulin resistance is associated with chronic hepatitis C and virus infection fibrosis progression. Gastroenterology 2003; 125: 1695-704.        [ Links ]

283. D’Souza R, Sabin CA, Foster GR. Insulin resistance plays a significant role in liver fibrosis in chronic hepatitis C and in the response to antiviral therapy. Am J Gastroenterol 2005; 100: 1509-15.        [ Links ]

284. Svegliati-Baroni G, Ridolfi F, Di Sario A, Casini A, Marucci L, Gaggiotti G, et al. Insulin and insulin-like growth factor-1 stimulate proliferation and type I collagen accumulation by human hepatic stellate cells: differential effects on signal transduction pathways. Hepatology 1999; 29: 1743-51.        [ Links ]

285. Cusi K, Maezono K, Osman A, Pendergrass M, Patti ME, Pratipanawair T, et al. Insulin resistance differentially affects the PI3-kinase-and MAP kinase-mediated signaling in human muscle. J Clin Invest 2000; 105: 311-20.        [ Links ]

286. Morrisey K, Evans RA, Wakefield L, Phillips AO. Translational regulation of renal proximal tubular epithelial cell transforming growth factor-beta 1 generation by insulin. Am J Pathol 2001; 159:1905-15.        [ Links ]

287. Paradis VP, Bonvoust G, Dargere F, Parfait D, Vidaud B, Conti M et al. High glucose and hyperinsulinemia stimulates connective tissue growth factor expression: a potential mechanism involved in progression to fibrosis in non-alcoholic steatohepatitis. Hepatology 2001; 34: 738-44.        [ Links ]

288. Canbay A, Taimr P, Torok N, Higuch H, Friedman S, Gores GJ. Apoptotic body engulfment by human stellate cell line is profibrogenic. Lab Invest 2003; 83: 655-63; .        [ Links ]

289. Fadok VA, Bratton DL, Konowal A, Freed PW, Westcott JY, Henson PM. Macrophages that have ingested apoptotic cells in vitro inhibit proinflammatory cytokine production through autocrine/paracrine mechanisms involving TGFβ, PGE2 and PAF. J Clin Invest 1998; 101: 890-8.        [ Links ]

290. Yin M, Gäbele E, Wheeler MD, Connor H, Bradford BU, Dikalova A, et al. Alcohol-induced free radicals in mice: direct toxicants or signaling molecules?. Hepatology 2001; 34: 935-42.        [ Links ]

291. C, Wand SC, Tsukamoto H, Brenner DA, Rippe RA. Expression of intracellular adhesion molecule 1 by activated hepatic stellate cells. Hepatology 1996; 24: 670-6.        [ Links ]

292. Marra F, Grandaliano G, Valente AJ, Pinzani M, Abboud HE. Cultured human liver fat-storing cells produce monocyte chemotactic protein-1. Regulation by proinflammatory cytokines. J Clin Invest 1993; 92: 1674-80.        [ Links ]

293. Sprenger H, Kaufmann A, Garn H, Lahme B, Gemsa D, Gressner AM. Induction of neutrophil-attracting chemokine in transforming rat hepatic stellate cells. Gastroenterology 1997; 113: 277-85.        [ Links ]

294. Maher JJ, Scott MK. Rat hepatic stellate cells produce cytokine-induced neutrophil chemoattractant (CINC) in primary culture and liver injury in vivo. Hepatology 1996; 24: 905A.        [ Links ]

295. Albano E, Mottaran E, Vidali M, Reale E, Saksena S, Occhino G, et al. Immune response towards lipid peroxidation products as a predictor of progression of non alcoholic fatty liver disease to advanced fibrosis. Gut 2005; 54: 987-93.        [ Links ]

296. Pessayre D, Berson A, Fromenty B, Mansouri A. Mitochondria in steatohepatitis. Semin Liver Dis 2001; 21: 57-69.        [ Links ]

297. Feldstein AE, Canbay A, Angulo P, Taniai M, Burgart LJ, Lindor KD, et al. Hepatocyte apoptosis and Fas expression are prominent features of human non alcoholic steatohepatitis. Gastroenterology 2003; 125: 437-43.        [ Links ]

298. Rodriguez CM, Cortez-Pinto H, Sola S. Apoptosis is a prominent feature of human alcoholic and nonalcoholic steatohepatitis. Hepatology 2001; 34: 672A.        [ Links ]

299. Ribeiro PS, Cortez-Pinto H, Solá S, Castro RE, Ramalho RM, Baptista A, et al. Hepatocyte apoptosis, expression of death receptors, and activation of NFκB in the liver of nonalcoholic and alcoholic steatohepatitis patients. Am J Gastroenterol 2004; 99: 1708-17.        [ Links ]

300. Ramalho RM, Cortez-Pinto H, Castro RE, Solá S, Costa A, Moura MC, et al. Apoptosis and Bcl-2 expresion in the livers of patients with steatohepatitis. Eur J Gastroenterol Hepatol 2006; 18: 21-9.        [ Links ]

301. Ashkenazi A, Dixt VM. Death receptors: signaling and modulation. Science 1998; 281: 1305-8.        [ Links ]

302. Green DR. Death and NFκB in T cell activation: Life at the edge. Molecular Cell. 2003; 11: 551-2.        [ Links ]

303. Baldwin AS. Control of oncogenesis and cancer therapy resistance by transcription factor NFκB. J Clin Invest 2001; 107: 241-6.        [ Links ]

304. Peter ME, Krammer PH. The CD95(APO-1/Fas) DISC and beyond. Cell Death Differ 2003; 10: 26-35.        [ Links ]

305. Li H, Zhu H, Xu CJ, Yuan J. Claveage of BID by caspase 8 mediates the mitochondrial damage in the Fas pathway of apoptosis. Cell 1998; 94: 491-501.        [ Links ]

306. Malhi H, Gores GJ, Lemasters JJ. Apoptosis and necrosis in the liver: a tale of two deaths? Hepatology 2006; 43: S31-S44.        [ Links ]

307. Bradham CA, Qian T, Streetz K, Trautwein C, Brenner DA, Lemasters JJ. The mitochondrial permeability transition is required for tumor necrosis factor alpha-mediated apoptosis and cytochrome c release. Mol Cell Biol 1998; 18: 6353-64.        [ Links ]

308. Li S, Zhao Y, He X, Kim TH, Kuharsky DK, Rabinowich H et al. Relief of extrinsic pathway inhibition by the Bid-dependent mitochondrial release of Smac in Fas-mediated hepatocytes apoptosis. J Biol Chem 2002; 277: 26912-20.        [ Links ]

309. Nechushtan A, Smith CL, Lamensdorf I, Yoon SH, Youle RJ. Bax and Bak coalesce into novel mitochondria-associated clusters during apoptosis. J Cell Biol 2001; 153: 1265-76.        [ Links ]

310. Crow MT, Mani K, Nam Y-J, Kitsis RN. The mitochondrial death pathway and cardiac myocyte apoptosis. Cir Res 2004; 95: 957-70.        [ Links ]

311. Green DR. Apoptotic pathways: ten minutes to dead. Cell 2005;121: 671-4.        [ Links ]

312. Amstrong JS. Mitochondrial membrana permeabilization: the sine qua non fro cell death. BioEssays 2006; 28: 253-60.        [ Links ]

313. Feldmann G, Haouzi D, Moreau A, Durand-Schneider AM, Bringier A, Berson A, et al. Opening of the mitochondrial permeability transition pore causes matrix expansion and outer membrane ruptura in Fas-mediated hepatic apoptosis in mice. Hepatology 2000; 31: 674-83.        [ Links ]

314. Kirkland RA, Windelborn JA, Kasprzak JM, Franklin JL. A Bax-induced pro-oxidant state is critical for cytochrome c release during programmaed neuronal death. J Neurol 2002; 22:6480-90.        [ Links ]

315. Nagai H, Matsumaru K, Feng G, Kaplowitz N. Reduced glutathione depletion causes necrosis and sensitization to tumor necrosis factoralpha-induced apoptosis in cultures mouse hepatocyte. Hepatology 2002; 36: 55-64.        [ Links ]

316. Ding W-X, Yin X-M. Dissection of the multiple mechanisms of TNF-alpha-induced apoptosis in liver injury. J Cell Mol Med 2004;8: 445-54.        [ Links ]

317. Matsumaru K, Ji C, Kaplowitz N. Mechanisms for sensitization to TNF-induced apoptosis by acute glutathione depletion in murine hepatocytes. Hepatology 2003; 37: 1425-34.        [ Links ]

318. Yin XM, Ding WX. Death receptor activation-induced hepatocyte apoptosis and liver injury. Curr Mol Med 2003; 3: 491-508.        [ Links ]

319. Park YC, et al. A novel mechanism of TRAF signaling revealed by structural and functional analyses of the TRADD-TRAF2 interaction. Cell 2000; 101: 777-87.        [ Links ]

320. Mari M, Colell A, Morales A, Paneda C, Varela-Nieto I, García-Ruiz C, et al. Acidic sphingomyelinase downregulates the liver-specific methionine adenosyltransferase IA, contribution to tumor necrosis factor-induced letal hepatitis. J Clin Invest 2004; 113: 892-904.        [ Links ]

321. Siskind L. Mitochondrial ceramide and the induction of apoptosis. J Bioener Biomem 2005; 37: 143-53.        [ Links ]

322. Listenberger LL, Ory DS, Schaffer JE. Palmitate-induced apoptosis can occur through a ceramide-independent pathway. J Biol Chem 2001; 276: 14890-5.        [ Links ]

323. Maestre I, Jordan J, Calvo S, Reig JA, Cena V, Soria B, et al. Mitochondrial dysfunction is envolved in apoptosis induced by serum withdrawal and fatty acids in the beta-cell line INS-1. Endocrinology 2003; 144: 335-45.        [ Links ]

324. Shimabukuro M, Zhou Y-T, Levi M, Unger RH. Fatty acid-induced beta cell apoptosis: a link between obesity and diabetes. Proc Natl Acad Sci USA. 1998; 95: 2498-502.        [ Links ]

325. Zhou YT, Grayburn P, Karim A, Shimabukuro M, Higa M, Baetens D, et al. Lipotoxic heart disease in obese rats: implications for human obesity. Proc Natl Acad Sci USA 2000; 97: 1784-9.        [ Links ]

326. Rodrigues B, Cam MC, McNeill JH. Myocardial substrate metabolism:implications for diabetic cardiomyopathy. J Mol Cell Cardiol 1995; 27: 169-79.        [ Links ]

327. Zhang CL, Lyngmo V, Nordoy A. The effects of saturated fatty acids on endothelial cells. Thromb Res 1992; 65: 65-75.        [ Links ]

328. Paumen MB, Ishida Y, Muramatsu M, Yamamoto M, Honjo T. Inhibition of carnitine palmitoyltransferase I augments sphingolipid synthesis and palmitate-induced apoptosis. J Biol Chem 1997; 272:3324-49.        [ Links ]

329. Hickson-Bick DL, Buja ML, McMillin JB. Palmitate-mediated alterations in the fatty acid metabolism of rat neonatal cardiac myocytes. J Mol Cell Cardiol 2000; 32: 511-9.        [ Links ]

330. Malhi HB, Werneburg N, Gores GJ. Hepatocyte lipoapoptosis is mediated by c-jun-n-terminal kinase (JNK) activation. Gastroenterology 2005; 128: 469.        [ Links ]

331. Kolesnick RN, Kronke M. Regulation of ceramide production and apoptosis. Annu Rev Physiol 1998; 60: 643-65.        [ Links ]

332. Unger RH. Lipotoxic diseases. Annu Rev Med 2002; 53: 319-39.        [ Links ]

333. Unger RH. Weapons of lean body mass destruction: the role of ectopic lipids in the metabolic syndrome. Endocrinology 2003; 144:5159-65.        [ Links ]

334. Mathias S, Pena LA, Kolesnick RN. Signal transduction of stress via ceramide. Biochem J 1998; 335: 465-80.        [ Links ]

335. Obeid LM, Hannun YA. Ceramide: a stress signal and mediator of growth suppression and apoptosis. J Cell Biochem 1995; 58: 191-8.        [ Links ]



Correspondence to:
J.A. Solís Herruzo.
Servicio de Medicina Aparato Digestivo.
Centro de Investigación.
Hospital Universitario 12 de Octubre.
Universidad Complutense.
Madrid. Ctra. de Andalucía, Km. 5,400.
28041 Madrid.

Recibido: 06-09-06
Aceptado: 06-09-06.

Creative Commons License Todo el contenido de esta revista, excepto dónde está identificado, está bajo una Licencia Creative Commons