Association between alcoholism and increased hepatic iron stores

Liver Iron Loading in Alcohol-Associated Liver Disease

Alcohol-associated liver disease (ALD) is a common chronic liver disease with increasing incidence worldwide. Alcoholic liver steatosis/steatohepatitis can progress to liver fibrosis/cirrhosis, which can cause predisposition to hepatocellular carcinoma. ALD diagnosis and management are confounded by several challenges. Iron loading is a feature of ALD which can exacerbate alcohol-induced liver injury and promote ALD pathologic progression. Knowledge of the mechanisms that mediate liver iron loading can help identify cellular/molecular targets and thereby aid in designing adjunct diagnostic, prognostic, and therapeutic approaches for ALD. Herein, the cellular mechanisms underlying alcohol-induced liver iron loading are reviewed and how excess iron in patients with ALD can promote liver fibrosis and aggravate disease pathology is discussed. Alcohol-induced increase in hepatic transferrin receptor-1 expression and up-regulation of high iron protein in Kupffer cells (proposed) facilitate iron deposition and retention in the liver. Iron is loaded in both parenchymal and nonparenchymal liver cells. Iron-loaded liver can promote ferroptosis and thereby contribute to ALD pathology. Iron and alcohol can independently elevate oxidative stress. Therefore, a combination of excess iron and alcohol amplifies oxidative stress and accelerates liver injury. Excess iron-stimulated hepatocytes directly or indirectly (through Kupffer cell activation) activate the hepatic stellate cells via secretion of proinflammatory and profibrotic factors. Persistently activated hepatic stellate cells promote liver fibrosis, and thereby facilitate ALD progression.

Fulminant Hepatic Failure With Minimal Alcohol Consumption in a 25-Year-Old Female With Hereditary Hemochromatosis: A Rare Case

Hereditary hemochromatosis (HH) is an inherited disorder in which organ damage and other clinical manifestations are commonly seen in patients with a homozygous mutation involving C282Y of the HFE gene, causing increased iron absorption in the intestine. The liver is the primary site of iron deposition, and excessive iron overload can eventually lead to hepatic cirrhosis. Patients who drink significant amounts of alcohol are more likely to develop cirrhosis, and in females, it is commonly seen after menopause. We describe a young female with hereditary hemochromatosis who developed fulminant hepatic failure with minimal alcohol consumption at age 25.

Deoxynivalenol: Mechanisms of action and its effects on various terrestrial and aquatic species

Deoxynivalenol, a type B trichothecene mycotoxin produced by Fusarium species of fungi, is a ubiquitious contaminant of cereal grains worldwide. Chronic, low dose consumption of feeds contaminated with DON is associated with a wide range of symptoms in terrestrial and aquatic species including decreased feed intake and feed refusal, reduced weight gain, and altered nutritional efficiency. Acute, high dose exposure to DON may be associated with more severe symptoms such as vomiting, diarrhea, intestinal inflammation and gastrointestinal hemorrhage. The toxicity of DON is partly related to its ability to disrupt eukaryotic protein synthesis via binding to the peptidyl transferase site of the ribosome. Moreover, DON exerts its effects at the cellular level by activating mitogen activated protein kinases (MAPK) through a process known as the ribotoxic stress response (RSR). The outcome of DON-associated MAPK activation is dose and duration dependent; acute low dose exposure results in immunostimulation characterized by the upregulation of cytokines, chemokines and other proinflammatory-related proteins, whereas longer term exposure to higher doses generally results in apoptosis, cell cycle arrest, and immunosuppression. The order of decreasing sensitivity to DON is considered to be: swine > rats > mice > poultry ≈ ruminants. However, studies conducted within the past 10 years have demonstrated that some species of fish, such as rainbow trout, are highly sensitive to DON. The aims of this review are to explore the effects of DON on terrestrial and aquatic species as well as its mechanisms of action, metabolism, and interaction with other Fusarium mycotoxins. Notably, a considerable emphasis is placed on reviewing the effects of DON on different species of fish.

Hemochromatosis and Xeroderma Pigmentosum: Two (Un)Suspicious Neighbors

A 51-year-old woman, clinically diagnosed with <i>Xeroderma pigmentosum</i> (XP), showed abnormalities in liver enzymes, high ferritin and transferrin saturation levels, with ultrasonographic features of chronic liver disease, in addition to skin hyperpigmentation. Genetic testing confirmed the clinical hypothesis of hereditary hemochromatosis (HH). Due to the known proximity of HFE (6p22.2) and POLH (6p21.1) genes, accountable for HH and the XP-V variant, respectively, a genetic test was offered and a rare variant of the POLH gene was identified. We report the first confirmed case, to our knowledge, of a patient diagnosed both with XP and HH, in whom two mutated neighbor genes – POLH and HFE – were identified, possibly the result of genetic linkage.

Cutaneous Manifestations of Chronic Liver Disease

Given the visibility of cutaneous findings, skin manifestations are often a presenting symptom of underlying systemic disease, including chronic liver disease. Many cutaneous signs and symptoms that correlate with chronic liver disease are common physical examination findings in patients with no history of liver disease. It is nonetheless important to be aware that these cutaneous findings may be an indication of underlying liver disease and often occur in the setting of such hepatic dysfunction. This article covers general cutaneous signs that may correlate with various liver diseases and describes specific cutaneous signs as they relate to more specific liver diseases.

Ferroptosis is involved in alcohol-induced cell death in vivo and in vitro

A critical pathogenic factor in the development of lethal liver failure is cell death induced by the accumulation of lipid reactive oxygen species. In this study, we discovered and illuminated a new mechanism that led to alcoholic liver disease via ferroptosis, an iron-dependent regulated cell death. Study in vitro showed that both necroptosis inhibitor and ferroptosis inhibitors performed significantly protective effect on alcohol-induced cell death, while apoptosis inhibitor and autophagy inhibitor had no such effect. Our data also indicated that alcohol caused the accumulation of lipid peroxides and the mRNA expression of prostaglandin-endoperoxide synthase 2, reduced the protein expression of the specific light-chain subunit of the cystine/glutamate antiporter and glutathione peroxidase 4. Importantly, ferrostatin-1 significantly ameliorated liver injury that was induced by overdosed alcohol both in vitro and in vivo. These findings highlight that targeting ferroptosis serves as a hepatoprotective strategy for alcoholic liver disease treatment.

Establishment of an alcoholic fatty liver disease model in mice

BACKGROUND

Alcoholic fatty liver disease (AFLD) defines an important stage in the progression of alcoholic liver disease (ALD), which is a major cause of morbidity and mortality worldwide.

OBJECTIVE

To establish a mouse model of AFLD.

METHODS

Male C57BL/6 mice were divided into the following two groups: (i) a control group, which was allowed free access to food and water and (ii) an alcohol-treated group, which was administered a 15% (v/v) alcohol solution instead of water. After 8-9 months of treatment, serum biochemical indexes, histopathological changes, liver triglyceride content, iron storage, and ferritin light chain protein expression were measured using an automatic biochemical analyzer, hematoxylin-eosin (HE) staining, a commercially available kit, Prussian blue staining, and Western blot analysis, respectively.

RESULTS

Compared with the control group, the alcohol-treated group displayed increased levels of serum LDH, ALT, and AST, decreased levels of ALB, and no significant change in levels of TP. Additionally, increased levels of serum TG, T-CHO, and LDL and decreased levels of serum GLU and HDL were observed in the alcohol-treated mice. HE staining showed that lipid vacuolization occurred in the livers of alcohol-treated mice. The alcohol-treated mice also exhibited increased liver triglyceride content. Moreover, Prussian blue staining and Western blot analysis demonstrated that chronic alcohol administration caused iron overloading of the liver.

CONCLUSIONS

Chronic administration of 15% (v/v) alcohol in the drinking water over 8-9 months caused AFLD in mice. Our results establish an AFLD model that represents a promising tool for the future study of the progression of ALD.

Endoplasmic Reticulum Stress and Ethanol Neurotoxicity

Ethanol abuse affects virtually all organ systems and the central nervous system (CNS) is particularly vulnerable to excessive ethanol exposure. Ethanol exposure causes profound damages to both the adult and developing brain. Prenatal ethanol exposure induces fetal alcohol spectrum disorders (FASD) which is associated with mental retardation and other behavioral deficits. A number of potential mechanisms have been proposed for ethanol-induced brain damage; these include the promotion of neuroinflammation, interference with signaling by neurotrophic factors, induction of oxidative stress, modulation of retinoid acid signaling, and thiamine deficiency. The endoplasmic reticulum (ER) regulates posttranslational protein processing and transport. The accumulation of unfolded or misfolded proteins in the ER lumen triggers ER stress and induces unfolded protein response (UPR) which are mediated by three transmembrane ER signaling proteins: pancreatic endoplasmic reticulum kinase (PERK), inositol-requiring enzyme 1 (IRE1), and activating transcription factor 6 (ATF6). UPR is initiated to protect cells from overwhelming ER protein loading. However, sustained ER stress may result in cell death. ER stress has been implied in various CNS injuries, including brain ischemia, traumatic brain injury, and aging-associated neurodegeneration, such as Alzheimer's disease (AD), Huntington's disease (HD), Amyotrophic lateral sclerosis (ALS), and Parkinson's disease (PD). However, effects of ethanol on ER stress in the CNS receive less attention. In this review, we discuss recent progress in the study of ER stress in ethanol-induced neurotoxicity. We also examine the potential mechanisms underlying ethanol-mediated ER stress and the interaction among ER stress, oxidative stress and autophagy in the context of ethanol neurotoxicity.

Biomarkers of iron status and trace elements in welders

Iron status was studied in 137 welders exposed to a geometric mean (GM) air concentration of 214 μg/m(3) (range 1-3230) of manganese (Mn), in 137 referents and in 34 former welders. The GM concentrations of S-ferritin were 119 (3-1498), 112 (9-1277) and 98 (12-989) μg/L (p=0.24) in the three groups, respectively. Also the GM concentrations of S-hepcidin were not significantly different between the groups (8.4 μg/L (2.8-117); 6.6 μg/L (1.8-100); 6.5 μg/L (1.2-22)) (p=0.22). Multiple linear regression analysis including all welders and referents showed an increase in the concentration of S-ferritin associated with having serum carbohydrate deficient transferrin (S-CDT) above the upper reference limit of ≥1.7%, indicating high alcohol consumption. Serum C-reactive protein was not associated with exposure as welders, but an association with S-ferritin was shown. The GM S-ferritin concentrations among all welders and referents with S-CDT≥1.7% were 157 μg/L (95% CI 113-218) as compared to 104 μg/L (95% CI 94-116) (p=0.02) in those with S-CDT<1.7%. The GM concentrations of Mn in biological fluids were higher in the welders as compared to the referents, while S-Fe, S-Co and B-Co were statistically significantly lower. This could suggest a competitive inhibition from Mn on the uptake of Fe and Co. Increasing concentrations of S-CDT was associated with higher S-Mn, S-Fe and B-Co in the multiple linear regression analysis. The association between S-CDT and S-Fe remained when all subjects with high S-CDT (≥1.7%) were excluded, suggesting increased uptake of Fe even at lower alcohol consumption.

Dietary and prophylactic iron supplements : Helpful or harmful?

Mild hypoferremia represents an aspect of the ability of the body to withhold iron from pathogenic bacteria, fungi, and protozoa, and from neoplastic cells. However, our iron-withholding defense system can be thwarted by practices that enhance iron overload such as indiscriminate iron fortification of foods, medically prescribed iron supplements, alcohol ingestion, and cigarette smoking. Elevated standards for normal levels of iron can be misleading and even dangerous for individuals faced with medical insults such as chronic infection, neoplasia, cardiomyopathy, and arthritis. We are becoming increasingly aware that the wide-spread hypoferremia in human populations is a physiological response to insult rather than a pathological cause of insult, and that attempts to correct the condition by simply raising iron levels may not only be misguided but may actually impair host defense.

Monitoring oxidative stress in patients with non-alcoholic and alcoholic liver diseases

Ethanol-induced liver injury may be linked, at least partly, to an oxidative stress resulting from increased free radical production and/or decreased antioxidant defence. Distinguishing alcoholic and non-alcoholic liver disease has important implications. This study looked at the possible changes between alcoholic and non-alcoholic liver diseases by examining the presence of oxidative damage, as monitored by several parameters relating to oxidative stress. Lipid peroxides concentration, superoxide dismutase activity and glutathione S-transferase activity increased, where as glutathione content, glutathione peroxidase activity and glutathione reductase activity decreased among the tested subjects in comparison to normal healthy group. Determination of these parameters may be valuable in the evaluation of liver disease. However, oxidative stress related enzymes and non-enzymes can not be utilized as a marker for alcoholic liver diseases, as these parameters responded in the same way after liver is damaged irrespective of their cause. Their level may help in determining the degree of liver damage. Degree of oxidative injury was similar in patients with non-alcoholic liver disease and in moderate drinkers; while significantly higher in heavy drinkers. The differences between the groups might be based on the type of liver pathological condition rather than its etiology (i.e. alcohol and non alcohol related causes).

An opium alkaloid-papaverine ameliorates ethanol-induced hepatotoxicity: Diminution of oxidative stress

In this communication, we show the modulatory potential of papaverine, an opium alkaloid and a well known vasodilator agent on the ethanol-induced hepatic oxidative stress in male Wistar rats. Ethanol treatment (50% v/v) enhanced lipid peroxidation significantly accompanied by a decline in the activities of glutathione peroxidase (G-Px), glutathione reductase (GR) and depletion in levels of hepatic glutathione (GSH). Ethanol administration increased hepatic glutathione-s-transferases (GST). Enhanced lipid peroxidation induced by ethanol was significantly reduced when papverine was coadministered (P<0.05). In addition, the depleted levels of glutathione and inhibited activities of G-Px and GR recovered significantly (P<0.05) levelling off to control values on co-exposure. Papaverine (200 mg/kg bw) effectively antagonised the ethanol-induced lipid peroxidation and impaired glutathione levels and glutathione dependent enzyme systems. Our results suggest that papaverine is an effective chemopreventive agent in the liver and may suppress the ethanol-induced hepatotoxicity.

Alcohol Activates TGF-Beta but Inhibits BMP Receptor-Mediated Smad Signaling and Smad4 Binding to Hepcidin Promoter in the Liver

Hepcidin, a key regulator of iron metabolism, is activated by bone morphogenetic proteins (BMPs). Mice pair-fed with regular and ethanol-containing L. De Carli diets were employed to study the effect of alcohol on BMP signaling and hepcidin transcription in the liver. Alcohol induced steatosis and TGF-beta expression. Liver BMP2, but not BMP4 or BMP6, expression was significantly elevated. Despite increased BMP expression, the BMP receptor, and transcription factors, Smad1 and Smad5, were not activated. In contrast, alcohol stimulated Smad2 phosphorylation. However, Smad4 DNA-binding activity and the binding of Smad4 to hepcidin promoter were attenuated. In summary, alcohol stimulates TGF-beta and BMP2 expression, and Smad2 phosphorylation but inhibits BMP receptor, and Smad1 and Smad5 activation. Smad signaling pathway in the liver may therefore be involved in the regulation of hepcidin transcription and iron metabolism by alcohol. These findings may help to further understand the mechanisms of alcohol and iron-induced liver injury.

Mechanisms of alcohol-induced endoplasmic reticulum stress and organ injuries

Alcohol is readily distributed throughout the body in the blood stream and crosses biological membranes, which affect virtually all biological processes inside the cell. Excessive alcohol consumption induces numerous pathological stress responses, part of which is endoplasmic reticulum (ER) stress response. ER stress, a condition under which unfolded/misfolded protein accumulates in the ER, contributes to alcoholic disorders of major organs such as liver, pancreas, heart, and brain. Potential mechanisms that trigger the alcoholic ER stress response are directly or indirectly related to alcohol metabolism, which includes toxic acetaldehyde and homocysteine, oxidative stress, perturbations of calcium or iron homeostasis, alterations of S-adenosylmethionine to S-adenosylhomocysteine ratio, and abnormal epigenetic modifications. Interruption of the ER stress triggers is anticipated to have therapeutic benefits for alcoholic disorders.

Effect of epigallocatechin-3-gallate on iron overload in mice with alcoholic liver disease

Iron has long been related to the pathological process of alcoholic liver disease (ALD). Liver iron overload is known to accelerate the development of ALD. In the present study we aimed to examine the effect of epigallocatechin-3-gallate (EGCG) on iron overload of ALD and to explore the potential mechanisms involved in its protection against ALD in mice. Male C57BL/6J mice were given alcohol by intragastric administration for 12 weeks. At the end of 8th week, ALD mice were treated for 4 weeks for 10, 20 and 30 mg kg(-1) EGCG by intraperitoneal injection. Liver injuries were assessed by histopathologic examination and Serum Alanine Aminotransferase (ALT) levels. Serum iron content, hepatic iron concentration and liver malondialdehyde (MDA) contents were examined. In addition, hepcidin mRNA levels and transferrin (Tf) and transferrin receptor 1 (TfR1) protein levels of liver tissue were also evaluated. Compared with model group, treatment of ALD mice with EGCG ameliorated liver injuries, decreased serum iron level, hepatic iron levels and liver MDA contents, increased hepcidin mRNA level and decreased Tf and TfR1 protein expression in the liver. The results of our study explain a new point of view that the protective effect of EGCG on ALD is associated with its iron-chelating property. The possible mechanisms are that EGCG affects hepatic iron uptake and inhibits iron absorption in the small intestinal.

Is the iron regulatory hormone hepcidin a risk factor for alcoholic liver disease?

Despite heavy consumption over a long period of time, only a small number of alcoholics develop alcoholic liver disease. This alludes to the possibility that other factors, besides alcohol, may be involved in the progression of the disease. Over the years, many such factors have indeed been identified, including iron. Despite being crucial for various important biological processes, iron can also be harmful due to its ability to catalyze Fenton chemistry. Alcohol and iron have been shown to interact synergistically to cause liver injury. Iron-mediated cell signaling has been reported to be involved in the pathogenesis of experimental alcoholic liver disease. Hepcidin is an iron-regulatory hormone synthesized by the liver, which plays a pivotal role in iron homeostasis. Both acute and chronic alcohol exposure suppress hepcidin expression in the liver. The sera of patients with alcoholic liver disease, particularly those exhibiting higher serum iron indices, have also been reported to display reduced prohepcidin levels. Alcohol-mediated oxidative stress is involved in the inhibition of hepcidin promoter activity and transcription in the liver. This in turn leads to an increase in intestinal iron transport and liver iron storage. Hepcidin is expressed primarily in hepatocytes. It is noteworthy that both hepatocytes and Kupffer cells are involved in the progression of alcoholic liver disease. However, the activation of Kupffer cells and TNF-α signaling has been reported not to be involved in the down-regulation of hepcidin expression by alcohol in the liver. Alcohol acts within the parenchymal cells of the liver to suppress the synthesis of hepcidin. Due to its crucial role in the regulation of body iron stores, hepcidin may act as a secondary risk factor in the progression of alcoholic liver disease. The clarification of the mechanisms by which alcohol disrupts iron homeostasis will allow for further understanding of the pathogenesis of alcoholic liver disease.

Role of alcohol in the regulation of iron metabolism

Patients with alcoholic liver disease frequently exhibit increased body iron stores, as reflected by elevated serum iron indices (transferrin saturation, ferritin) and hepatic iron concentration. Even mild to moderate alcohol consumption has been shown to increase the prevalence of iron overload. Moreover, increased hepatic iron content is associated with greater mortality from alcoholic cirrhosis, suggesting a pathogenic role for iron in alcoholic liver disease. Alcohol increases the severity of disease in patients with genetic hemochromatosis, an iron overload disorder common in the Caucasian population. Both iron and alcohol individually cause oxidative stress and lipid peroxidation, which culminates in liver injury. Despite these observations, the underlying mechanisms of iron accumulation and the source of the excess iron observed in alcoholic liver disease remain unclear. Over the last decade, several novel iron-regulatory proteins have been identified and these have greatly enhanced our understanding of iron metabolism. For example, hepcidin, a circulatory antimicrobial peptide synthesized by the hepatocytes of the liver is now known to play a central role in the regulation of iron homeostasis. This review attempts to describe the interaction of alcohol and iron-regulatory molecules. Understanding these molecular mechanisms is of considerable clinical importance because both alcoholic liver disease and genetic hemochromatosis are common diseases, in which alcohol and iron appear to act synergistically to cause liver injury.

Hemochromatosis gene mutations, liver function tests and iron status in alcohol-dependent patients admitted for detoxification

BACKGROUND

Screening of target populations for hemochromatosis (HFE) gene allele status has been recommended. Alcoholic liver disease may be associated with iron overload and there is evidence of excessive alcohol consumption among patients with hereditary hemochromatosis. This study determined the HFE gene allele status in alcohol-dependent patients and explored the associations between iron status, liver enzymes, and HFE status.

METHODS

A total of 151 consecutive patients admitted for alcohol detoxification were tested for HFE mutations, iron status, and liver function tests. The prevalence data were compared with those from a New Zealand population. manova was used to compare liver function tests and iron status for subjects with different HFE mutations.

RESULTS

Three compound heterozygotes, one homozygote for C282Y, and one homozygote for H63D were found among the 151 patients. For the remaining 146 patients, there was no difference in the distribution of heterozygote status by allele, compared to the general New Zealand population. No HFE mutation: general population 64.4%, alcohol-dependent patients 64.4%; H63D: general population 23.6%, alcohol-dependent patients 28.1%; C282Y: general population 11.9%, alcohol-dependent patients 7.5% (P = 0.20). There was no relationship between liver function tests or iron status and HFE mutation status among the study group.

CONCLUSIONS

No evidence has been found in the present that HFE allele status prevalence is different from the general population or associated with different liver function or iron status among alcohol-dependent patients. The cause of altered iron status among alcohol-dependent patients does not appear to be related to HFE status.

Iron overload syndromes and the liver

Iron can accumulate in the liver in a variety of conditions, including congenital, systemic iron-loading conditions (hereditary hemochromatosis), conditions associated with systemic macrophage iron accumulation (transfusions, hemolytic conditions, anemia of chronic disease, etc), in some hepatitidies (hepatitis C, alcoholic liver disease, porphyria cutanea tarda), and liver-specific iron accumulation of uncertain pathogenesis in cirrhosis. The anatomic pathologist will be faced with the task of determining whether iron accumulation in the liver is significant and, if so, the nature of the disease that lead to the accumulation (ie diagnosis). The tools available to the pathologist include (most importantly) histologic examination with iron stain, quantitative iron analysis, clinical history, laboratory iron tests (serum iron and iron-binding capacity, serum ferritin) and germline genetic analysis for mutations in genes known to be associated with hemochromatosis (HFE, ferroportin, hepcidin, hemojuvelin, transferrin receptor-2). This article provides an overview of the above.

Alcohol, oxidative stress and free radical damage

The involvement of free radical mechanisms in the pathogenesis of alcoholic liver disease (ALD) is demonstrated by the detection of lipid peroxidation markers in the liver and the serum of patients with alcoholism, as well as by experiments in alcohol-feed rodents that show a relationship between alcohol-induced oxidative stress and the development of liver pathology. Ethanol-induced oxidative stress is the result of the combined impairment of antioxidant defences and the production of reactive oxygen species by the mitochondrial electron transport chain, the alcohol-inducible cytochrome P450 (CYP) 2E1 and activated phagocytes. Furthermore, hydroxyethyl free radicals (HER) are also generated during ethanol metabolism by CYP2E1. The mechanisms by which oxidative stress contributes to alcohol toxicity are still not completely understood. The available evidence indicates that, by favouring mitochondrial permeability transition, oxidative stress promotes hepatocyte necrosis and/or apoptosis and is implicated in the alcohol-induced sensitization of hepatocytes to the pro-apoptotic action of TNF-alpha. Moreover, oxidative mechanisms can contribute to liver fibrosis, by triggering the release of pro-fibrotic cytokines and collagen gene expression in hepatic stellate cells. Finally, the reactions of HER and lipid peroxidation products with hepatic proteins stimulate both humoral and cellular immune reactions and favour the breaking of self-tolerance during ALD. Thus, immune responses might represent the mechanism by which alcohol-induced oxidative stress contributes to the perpetuation of chronic hepatic inflammation. Together these observations provide a rationale for the possible clinical application of antioxidants in the therapy for ALD.

Compound overload of copper and iron in patients with Wilson's disease

This review of the copper-iron interaction in Wilson's disease was mainly based on ten patients (three females and seven males) studied in our institutes because the genetic tests of ATP7B for Wilson's disease of primary copper toxicosis and HFE for hemochromatosis, the biochemical parameters of copper and iron, and morphological studies on biopsied liver specimens were complete. All patients had hypoceruloplasminemia and hepatic lesions compatible with Wilson's disease. One patient was homozygous and nine patients were compound heterozygous for the mutations in ATP7B, and all patients were free from the major mutation, C282Y, of HFE. The biochemical parameters of iron metabolism were not specific, except for serum ferritin concentration. Judging from the traditional criteria, seven patients had hyperferritinemia. Histochemical iron was stained in the livers of seven patients and histochemical copper was found in nine patients. Microanalysis was more sensitive than histochemistry, detecting copper and iron accumulation in the hepatocellular lipofuscin particles of all patients. Using an improved fixative, intralipofuscin distribution was found to be different between cuprothionein and iron complexes. Iron overload in Wilson's disease might be worsened after treatment because of the close relation to hypoceruloplasminemia, in which the iron efflux from the liver to the circulation is disturbed.

Influence of diets with cereal grains contaminated by graded levels of two Fusarium toxins on selected enzymatic and histological parameters of liver in gilts

Feeding experiments with diets containing Fusarium toxin-contaminated wheat were conducted to clarify the pathogenesis of enzymatic and histopathological effects of Fusarium toxins on porcine liver cells. A total of 36 prepuberal gilts were divided into four groups and fed diets with increasing proportions of Fusarium toxin-contaminated wheat at a total wheat proportion of 40% over a period of 35 days. The concentrations of the indicator toxins deoxynivalenol (DON) and zearalenone (ZON) which were analyzed by HPLC methods were 210/4, 3070/88, 6100/235, and 9570/358 microg/kg in the diets fed to groups I-IV, respectively. The feeding of mycotoxin-contaminated diets did not cause gross pathological findings in the livers of the animals. Liver tissues were subjected to enzymatic, histological, and ultrastructural examinations. The percentages of the stained areas in periodic acid-Schiff (PAS), Berlin-Blue, and Masson Goldner's trichrome stainings were calculated using the AnalySIS 3.4-system. Significant histopathological findings of alterations with varying degrees in glycogen reduction and increase of hemosiderin particles were found in the liver cells of groups II, III and IV. The thickness of interlobular connective tissue septum in liver cells was significantly increased in groups III and IV. Qualitative ultrastructural alterations were observed in hepatocytes of gilts in groups III and IV. Dependent upon the mycotoxin concentration in the diet, the hepatocytes developed a dose-dependent, extensive, smooth endoplasmic reticulum, exhibited loss of ribosomes, and acquired an increased number of fatty and autophagic vacuoles. However, liver damage as measured by prominent elevated transaminase activities in serum was not detected. Together, the histopathological results provide evidence of liver dysfunction in the absence of clinical signs, especially in pigs fed higher concentrations of Fusarium toxin-contaminated wheat.

Effects of HFE gene mutations and alcohol on iron status, liver biochemistry and morbidity

BACKGROUND AND AIMS

The aims of the present study were to determine: (i) whether alcohol consumption is greater in individuals with HFE mutations; and (ii) whether common HFE mutations modify the effects of alcohol on serum iron and liver biochemistry or morbidity.

METHODS

The residents of the town of Busselton in Western Australia were subject to cross-sectional health surveys between 1966 and 1983. In 1994/1995 all surviving participants of the earlier surveys were invited to take part in a follow-up survey. Logistic, linear and Poisson log-linear regression analyses were performed in 1490 men and 1452 women from the 1994/1995 survey to assess the relationships between HFE mutations, alcohol, iron levels, liver biochemistry and morbidity.

RESULTS

Heavy or moderate alcohol consumption was present in 7% or 36% of men and 0.5% or 12% of women, respectively. Alcohol consumption strongly influenced levels of serum ferritin and gamma glutamyl transpeptidase (GGT) and mean cell volume (MCV) in men and women but only alanine aminotransferase (ALT) levels in women. These effects were independent of HFE gene mutations. Hospital admission rates for respiratory disorders were higher in men with the C282Y mutation.

CONCLUSIONS

Alcohol consumption strongly influences serum ferritin and GGT levels and MCV in men and women but only ALT levels in women, and these effects are independent of HFE mutations. HFE gene mutations do not predispose to moderate or heavy alcohol consumption. The C282Y mutation is associated with increased respiratory admission rates in men.

The effect of alcohol consumption on the prevalence of iron overload, iron deficiency, and iron deficiency anemia

BACKGROUND & AIMS

Our aim was to investigate the relationship between alcohol consumption and iron overload, iron deficiency, or iron deficiency anemia in the U.S. population.

METHODS

Adult participants of the Third National Health and Nutrition Examination Survey who did not consume alcohol (n = 8839) were compared with participants who consumed < or =1 (n = 4976), >1 to < or =2 (n = 1153), or >2 (n = 915) alcoholic drinks/day during the preceding 12 months. We examined the following markers of iron overload: elevated serum transferrin-iron saturation (TS) level (>45%, >50%, and >60%), elevated serum ferritin level (>300, >400, >500, and >600 ng/mL), and combinations of both elevated serum TS and ferritin levels. Iron deficiency was defined as the presence of at least 2 of the following: serum ferritin level <12 ng/mL, serum TS level <15%, and erythrocyte protoporphyrin level >1.24 micromol/L. Iron deficiency anemia was defined as the presence of both iron deficiency and anemia.

RESULTS

Compared with nondrinkers, the prevalence of all markers of iron overload was significantly elevated among those who consumed >2 alcoholic drinks/day after adjusting for potential confounders. Consumption of any amount of alcohol was associated with a 40% reduction in the risk of iron deficiency anemia.

CONCLUSIONS

Consumption of up to 2 alcoholic drinks/day seems to be associated with reduced risk of iron deficiency and iron deficiency anemia without a concomitant increase in the risk of iron overload. Consumption of >2 alcoholic drinks/day is associated with a significant elevation in the risk of iron overload.

Iron overload enhances the development of experimental liver cirrhosis in mice

The role of iron in initiating liver fibrosis in iron overload diseases is not clearly established. Partly, this is due to the lack of suitable animal models that can produce the full liver pathology seen in genetic hemochromatosis. Recent advances in this field have demonstrated that iron may be interacting with other potential liver-damaging agents. The aim of this study was to investigate if feeding with carbonyl iron (CI) facilitates the development of carbon tetrachloride (CCl4)-induced liver fibrosis in the mouse. Mice were given a diet containing 3% CI and treated with CCl4 intraperitoneally twice weekly and 5% alcohol added to the drinking water for 12 weeks. Hepatic iron content increased 15- and 22-fold in animals receiving CI and CI + CCl4. At histological examination, iron-laden hepatocytes were found in CI treated animals, whereas these were absent in animals not exposed to CI. Mice receiving iron-enriched diet alone showed a mild fibrosis. Conversely, a marked collagen deposition was observed in CCl4 and CI + CCl4 groups. In particular, in this latter group, there was evidence of liver cirrhosis. Biochemical evaluation of collagen content substantiated histologic analysis. These results demonstrate that the addition of iron facilitates the development of cirrhosis in animals exposed to subtoxic doses of CCl4. This model may be useful in exploring the pathogenesis of liver cirrhosis. Moreover, its use in genetically altered mouse strains might provide new insight on the role of iron in fibrosis.

Effect of zinc on hepatic lipid peroxidation and antioxidative enzymes in ethanol-fed rats

A 3-ml aliquot of 30% ethanol was fed daily to normal as well as zinc-treated (227 mg l(-1)) rats for periods of 2, 4 and 8 weeks. A highly significant increase in the levels of hepatic lipid peroxidation was observed in ethanol-fed rats after 4 and 8 weeks of treatment. On the other hand, the levels of lipid peroxidation came down significantly following ethanol feeding to zinc-treated rats. The activities of glutathione peroxidase (GPx), catalase and superoxide dismutase (SOD) in liver were elevated significantly after ethanol administration to rats for durations of 2, 4 and 8 weeks. Interestingly, zinc treatment to rats given ethanol was able to bring down the elevated levels of SOD, catalase and GPx to within normal limits, However, zinc administration alone did not cause any significant alteration in the activities of these antioxidative enzymes.

Excess alcohol greatly increases the prevalence of cirrhosis in hereditary hemochromatosis

BACKGROUND & AIMS

The progression of fibrosis to cirrhosis is the most significant prognostic factor in hereditary hemochromatosis. We aimed to determine the range of hepatic iron concentration associated with cirrhosis in the absence of alcohol and other pro-fibrogenic cofactors and to quantify the contribution of excess alcohol consumption to the development of cirrhosis.

METHODS

Liver biopsy data were evaluated on 224 C282Y homozygous hemochromatosis subjects. To determine the effect of alcohol alone on the development of fibrosis, subjects with viral hepatitis or nonalcoholic steatohepatitis were excluded. Subjects were divided into those who consumed less than 60 g alcohol per day and those who consumed 60 g per day or more.

RESULTS

Seven percent of subjects who consumed less than 60 g per day had severe fibrosis/cirrhosis compared with 61% of excess alcohol consumers.

CONCLUSIONS

Hemochromatosis subjects who drink more than 60 g alcohol per day are approximately 9 times more likely to develop cirrhosis than those who drink less than this amount, and the range of hepatic iron concentration associated with cirrhosis in the absence of cofactors was 233-675 micromol/g dry weight.

Haptoglobin phenotype 2-2 overrepresentation in Cys282Tyr hemochromatotic patients

BACKGROUND/AIMS

Patients with genotypic Cys282Tyr homozygous hemochromatosis differ largely in phenotypic presentation. The HFE mutation on itself does not explain the different manifestations of hemochromatosis. We hypothesized that the genetic haptoglobin (Hp) polymorphism, because of its effect on iron metabolism, could be a modifying factor that influences the clinical presentation of hereditary hemochromatosis.

METHODS

In 167 Cys282Tyr homozygous hemochromatotic patients, the frequencies of Hp types (1-1, 2-1 and 2-2) and alleles (Hp1, Hp2) were compared with those in 918 healthy subjects. Clinical and laboratory indices of iron overload were incorporated in the analysis.

RESULTS

The Hp 2-2 type was overrepresented in the patient group (P<0.01). Male patients carrying Hp 2-2 had higher serum iron (P=0.003) and ferritin levels (P=0.03) than those with a Hp 1-1 or 2-1 type. The amount of iron removed with phlebotomy was also higher in Hp 2-2 patients (P=0.03).

CONCLUSIONS

The Hp 2-2 type is overrepresented among Cys282Tyr homozygous hemochromatotic patients. At diagnosis, iron overload was more pronounced in male patients carrying Hp 2-2. Our data suggest that Hp polymorphism affects iron metabolism in hereditary hemochromatosis.

Effects of alcohol consumption on indices of iron stores and of iron stores on alcohol intake markers

BACKGROUND

Alcohol increases body iron stores. Alcohol and iron may increase oxidative stress and the risk of alcohol-related liver disease. The relationship between low or "safe" levels of alcohol use and indices of body iron stores, and the factors that affect the alcohol-iron relationship, have not been fully characterized. Other aspects of the biological response to alcohol use have been reported to depend on iron status.

METHODS

We have measured serum iron, transferrin, and ferritin as indices of iron stores in 3375 adult twin subjects recruited through the Australian Twin Registry. Information on alcohol use and dependence and smoking was obtained from questionnaires and interviews.

RESULTS

Serum iron and ferritin increased progressively across classes of alcohol intake. The effects of beer consumption were greater than those of wine or spirits. Ferritin concentration was significantly higher in subjects who had ever been alcohol dependent. There was no evidence of interactions between HFE genotype or body mass index and alcohol. Alcohol intake-adjusted carbohydrate-deficient transferrin was increased in women in the lowest quartile of ferritin results, whereas adjusted gamma-glutamyltransferase, aspartate aminotransferase, and alanine aminotransferase values were increased in subjects with high ferritin.

CONCLUSIONS

Alcohol intake at low level increases ferritin and, by inference, body iron stores. This may be either beneficial or harmful, depending on circumstances. The response of biological markers of alcohol intake can be affected by body iron stores; this has implications for test sensitivity and specificity and for variation in biological responses to alcohol use.

Use of rat models to mimic alterations in iron homeostasis during human alcohol abuse and cirrhosis

With alcoholism, there are marked disturbances in iron homeostasis that are linked to alterations in serum transferrin and ferritin concentrations. This study identifies rat models of alcohol abuse that closely mimic these disturbances. Male rats were placed in one of the following three protocols: (1) pair-feeding of liquid diets for 1-8 weeks; (2) agar-block feeding for 8 weeks; or (3) generation of cirrhosis with CCl(4). Serum samples were analyzed for ferritin, transferrin, and iron levels, and the transferrin iron saturation and ferritin/transferrin ratios were calculated. Liver iron concentrations were also determined. Serum transferrin levels were elevated in animals fed alcohol for 8 weeks in pair-feeding and agar-block feeding protocols, but reduced in rats with cirrhosis. Serum ferritin concentration was reduced in rats fed ethanol in the liquid diet, but increased in rats consuming ethanol in agar blocks, in rats pair-fed the liquid control diet, and in rats with cirrhosis. This finding was mirrored by liver nonheme iron concentrations in all experimental groups, but not in the corresponding control groups. Serum iron levels were significantly elevated only in rats fed the liquid control diet. There was a progressive decrease in transferrin iron saturation and ferritin/transferrin ratios for animals fed ethanol in the liquid diet, but not when ethanol was ingested from agar blocks. The development of cirrhosis resulted in elevated liver iron concentrations and doubled ferritin/transferrin ratios. It is concluded that these models may be used to study disturbances in iron homeostasis that occur during alcohol abuse and the (subsequent) development of liver disease.

Histological evaluation of iron in liver biopsies: relationship to HFE mutations

OBJECTIVE

Hepatic iron overload is observed in many forms of chronic liver disease. Hereditary hemochromatosis (HH) results in hepatic iron overload and is associated with 2 missense mutations in the HFE gene. The aim of this study was to define the usefulness of the histological pattern of iron deposition in determining the probability of an iron-loaded patient having HFE-related iron overload.

METHODS

This study assessed liver biopsies containing stainable iron from 103 patients with various liver diseases; clinical information included hepatic iron concentration and HFE genotype (C282Y, H63D). The biopsies were evaluated using a reproducible histological scoring system for iron deposition. Three separate components of histological iron deposition were recorded: 1) pattern (primarily hepatocellular with a zonal gradient, or reticuloendothelial without an obvious zonal gradient), 2) pattern score to denote the extent of iron within the acinus, and 3) quantitation grade of iron granules within affected hepatocytes.

RESULTS

The predominantly hepatocellular pattern (HH pattern) was observed in 72 biopsies of which only 42 were from patients homozygous for the C282Y mutation, indicating that this pattern alone cannot be used as a surrogate marker for HH genotype. The predominantly reticuloendothelial pattern (non-HH pattern) was observed in the remaining 31 patients, none of whom was compound heterozygous or homozygous for the C282Y mutation (negative predictive value: 100%). Thus, the non-HH, reticuloendothelial pattern reliably predicts the absence of homozygosity for the C282Y mutation.

CONCLUSIONS

The use of histological evaluation for iron deposition is simple, assists in expanding information communicated from histopathologic observations, and may be clinically useful in determining the necessity of further evaluation of HFE genotype in subjects with histological evidence of hepatic iron overload.

Nonalcoholic steatohepatitis: a proposal for grading and staging the histological lesions

OBJECTIVE

Steatohepatitis is a morphological pattern of liver injury that may be seen in alcoholic or nonalcoholic liver disease. This pattern may occur with obesity, diabetes, the use of certain drugs, or the cause may be idiopathic. The well-recognized histopathological features of nonalcoholic steatohepatitis (NASH) include hepatocellular steatosis and ballooning, mixed acute and chronic lobular inflammation, and zone 3 perisinusoidal fibrosis. Currently, there are no systems for grading necroinflammatory activity or for staging fibrosis as exist for various other forms of chronic liver disease. The purpose of this study was to develop such a grading and staging system and was based on review of liver biopsies from 51 patients with nonalcoholic steatohepatitis from Saint Louis University Health Sciences Center.

METHODS

For determination of grade, 10 histological variables of activity were initially analyzed; an overall impression of mild, moderate, and severe was made and the variables considered to be most significant were used to develop the necroinflammatory grade.

RESULTS

The histological lesions considered to be significant were: steatosis, ballooning, and intra-acinar and portal inflammation. A staging score was developed to reflect both location and extent of fibrosis. The fibrosis score was derived from the extent of zone 3 perisinusoidal fibrosis with possible additional portal/periportal fibrosis and architectural remodeling. Fibrosis stages are as follows: Stage 1, zone 3 perisinusoidal fibrosis; Stage 2, as above with portal fibrosis; Stage 3, as above with bridging fibrosis; and Stage 4, cirrhosis.

CONCLUSION

We propose a grading and staging system that reflects the unique histological features of nonalcoholic steatohepatitis.

Hepatic lipid peroxidation in hereditary hemochromatosis and alcoholic liver injury

Studies in experimental animals have indicated that enhanced lipid peroxidation may play a role in the hepatic injury produced by iron overload or by excessive alcohol consumption. The aim of this study was to compare the formation of lipid peroxidation-derived aldehydes in the liver of patients with hereditary hemochromatosis (HH) and alcohol abuse. Liver biopsy specimens from 10 nondrinking patients with HH were evaluated. These patients were classified as having HH based on hepatic iron index or human leukocyte antigen identity with a known proband. All patients were homozygous for the Cys282Tyr mutation. In addition, 8 patients with alcoholic liver disease were examined, 2 of whom also had hemochromatosis. For comparison, 17 patients with liver diseases unrelated to iron overload or alcohol abuse were studied. Liver biopsy specimens were immunostained for protein adducts with malondialdehyde and 4-hydroxynonenal. Both malondialdehyde- and 4-hydroxynonenal-protein adducts were found from liver specimens of patients with HH and alcohol abuse in more abundant amounts than from patients in a control group. In alcoholics the adducts were primarily in zone 3, whereas in hemochromatosis staining had an acinar zone 1 predominance, which followed the localization of iron. The most abundant amounts of protein adducts were noted in patients with alcohol abuse plus iron overload. The data support the concept that both chronic alcohol use and iron overload induce hepatic lipid peroxidation. Through formation of reactive aldehydic products, excessive alcohol consumption and iron overload may have additive hepatotoxic effects.

Carbohydrate-deficient transferrin, a sensitive marker of chronic alcohol abuse, is highly influenced by body iron

Carbohydrate-deficient transferrin (CDT), a microheterogeneous form of serum transferrin (Tf), has been proposed as the most reliable marker of chronic alcohol consumption, although unexplained false-positive and -negative results have been reported. We investigated whether body iron influenced CDT serum levels by studying alcohol abusers with or without iron overload and nonabusers with iron deficiency or iron overload caused by genetic hemochromatosis (GH). In alcohol abusers, CDT was significantly lower in the presence of iron overload than in the absence (24.6 +/- 16.5 U/L vs. 33.3 +/- 11.7 U/L; P <.01), with false-negative results almost exclusively in patients with iron overload. Similarly, in nonabusers with GH, CDT was lower than in normal controls (9.6 +/- 2. 2 U/L vs. 15.7 +/- 3.3 U/L; P <.0001), whereas, patients with iron deficiency anemia had significantly higher levels than controls (28. 1 +/- 5.8 U/L vs. 15.7 +/- 3.3 U/L; P <.0001). In nonabusers, iron supplementation therapy significantly decreased CDT levels in patients with iron deficiency anemia (33.7 +/- 6.6 U/L vs. 21.7 +/- 5.2 U/L; P =.0007), while iron-depletion treatment significantly increased CDT levels in patients with GH (9.7 +/- 2.0 U/L vs. 14.7 +/- 4.0 U/L; P =.001). Alcohol abusers had a significant relationship between liver iron concentration (LIC) and the reciprocal of CDT (r =.65; P <.0001), while in nonabusers, there was a significant correlation between Tf and CDT (r =.72; P <.0001). In conclusion, CDT serum levels are markedly affected by the patient's iron status, with iron overload reducing its sensitivity in alcohol abusers and iron deficiency its specificity in nonabusers. CDT can be considered a reliable marker of alcohol abuse only when iron stores are normal.

Phenotypic expression of HFE mutations: a French study of 1110 unrelated iron-overloaded patients and relatives

BACKGROUND & AIMS

Two mutations have been described in the HFE gene: C282Y and H63D. The aim of this study was to determine the phenotype of the different HFE genotypes.

METHODS

Clinical symptoms and iron data were examined according to HFE genotypes in 531 unrelated patients with unexplained liver iron overload and 579 relatives of hemochromatotic patients.

RESULTS

Non-C282Y +/+ patients did not markedly differ in terms of iron overload or clinical expression according to genotype, except for compound heterozygotes, who had slightly increased transferrin saturation. This contrasted with the strikingly increased expression in C282Y homozygotes. Similar phenotype/genotype correlations were observed in relatives based on serum iron test results. Family transmission of iron overload linked to HFE was exceptional in non-C282Y +/+ siblings and frequent in C282Y homozygotes.

CONCLUSIONS

Iron overload in patients with the non-C282Y +/+ genotype is mild to moderate, strikingly lower than in C282Y homozygotes, and is not influenced by HFE genotype, except, to a small extent, for compound heterozygotes. The role of H63D mutation therefore seems to be marginal.

Hepatic iron overload in patients with chronic viral hepatitis: role of HFE gene mutations

Mild to moderate hepatic iron overload is frequent in patients with chronic viral hepatitis (CH). We evaluated the role of hemochromatosis (HFE) gene mutations and other acquired factors in the development of iron overload in these patients. We studied 110 patients with chronic B or C viral hepatitis (31 women, 79 men), including 20 with cirrhosis, and 139 controls. Hepatic iron was evaluated by semiquantitative analysis in all the patients, and hepatic iron concentration (HIC) was determined in 97 of them (26 women, 71 men). C282Y and H63D mutations were sought in all the subjects by a polymerase chain reaction-restriction assay. The frequency of HFE genotypes and alleles did not differ in patients and controls. No relation was detected between hepatic iron stores and HFE gene mutations in women. In men, all C282Y heterozygotes had iron overload, and the H63D mutation was significantly more frequent in patients with more marked hepatic siderosis than in those with mild or no siderosis (P = .0039) and in controls (P = .0008). Heavy alcohol intake and hepatic cirrhosis were also associated with increased hepatic iron stores in the men. In the 71 men in whom HIC was measured, multiple regression analysis showed that this variable was related independently only to alcohol intake and HFE gene mutations. We suggest that in patients with CH, iron accumulates in the liver as the result of an interplay between genetic and acquired factors, and that increased liver iron stores may influence progression toward liver fibrosis.

Nutritional factors adversely influencing the glucose/insulin system

For the majority of people, particularly if they do not smoke, the food they eat is the largest controllable factor determining their long-term health. The disproportionate consumption of foods high in fat, especially high in saturated fat, and high in simple sugars at the expense of foods high in complex carbohydrate and unsaturated fat has the potential of inducing abnormal metabolic processes in a normal healthy individual and to promote chronic degenerative diseases. Some of the effects of individual macronutrients such as fat, refined sugars and alcohol in promoting abnormalities in glucose/insulin system are presented. These nutrients were chosen because they also have the ability to alter oxidative state of the individual, which in turn could affect the glucose/insulin system. This review focuses on the role of dietary nutrient interactions in influencing the glucose/insulin system through the generation of reactive oxygen species. The importance of dietary macronutrient interaction with micronutrients such as copper and iron and the potential it has in affecting the glucose/insulin system is addressed.

Effect of moderate alcohol intake on lipid peroxidation in plasma, erythrocyte and leukocyte and on some antioxidant enzymes

Plasma, erythrocyte and leukocyte lipid peroxidation, erythrocyte superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and plasma gamma-glutamyl transferase (GGT) levels were investigated in 36 healthy non-drinkers aged between 18-55 years (mean 38.7) and 72 alcohol drinkers aged between 20-48 years (mean 35.3) in order to determine the oxidative effect of alcohol. Erythrocyte lipid peroxidation of the drinkers (measured in terms of MDA) was found to be significantly (P < 0.05) reduced compared to that of controls. However, when Tukey-HSD and F test with ANOVA were performed, that significance disappears in those who consume less than 140 g of alcohol per day and persists in those who consume more than 140 g of alcohol per day (P < 0.05). Plasma GGT level was significantly increased compared to that of controls (P < 0.001). Also, there was a significant (P = 0.01) correlation between serum GGT level and the amount of alcohol. There were no significant differences between all the other parameters of both groups. Reduced lipid peroxidation of erythrocytes without any accompanying increase in the activities of antioxidant enzymes shows that another mechanism might be responsible for this finding. This mechanism was thought to be an alteration in lipid composition of erythrocyte membranes.

Studies on genotoxic effects of iron overload and alcohol in an animal model of hepatocarcinogenesis

BACKGROUND/AIMS

In order to examine whether iron and alcohol act synergistically during tumor initiation in vivo, we investigated the effects of dietary iron overload and a liquid ethanol-containing diet on the initiation phase of the Solt & Farber model of chemical hepatocarcinogenesis.

METHODS

Following dietary supplementation with carbonyl iron for 8 weeks and ethanol pair-feeding according to Lieber deCarli for 5 weeks, animals were subjected to partial hepatectomy in order to induce regenerative cell proliferation and thereby "fix" putative DNA lesions. Levels of malondialdehyde, reduced and oxidized ubiquinone-9, alpha-tocopherol and 8-oxo-2'-deoxyguanosine were analyzed in liver tissue removed at the time of partial hepatectomy, and blood was collected for determination of alanine amino-transferase activities. Following a 2-week recovery period, promotion was achieved with 0.02% dietary 2-acetylaminofluorene and carbon tetrachloride. Two weeks after the completion of promotion, animals were sacrificed and the number of preneoplastic, glutathione S-transferase 7,7-positive lesions counted. Animals initiated with diethylnitrosamine served as a positive control group.

RESULTS

Serum aminotransferase activities were significantly increased, and hepatic contents of ubiquinol-9 (reduced ubiquinone-9) were significantly decreased in animals exposed to the combination of iron and ethanol in comparison to the other groups. Livers from iron-treated animals had decreased levels of alpha-tocopherol and increased contents of malondialdehyde, whereas treatment with ethanol did not further enhance these alterations. Levels of 8-oxo-2'-deoxyguanosine were not significantly different in animals treated with iron, ethanol or iron + ethanol as compared with controls. The number of preneoplastic foci at the time of sacrifice was not increased in livers exposed to iron and/or ethanol as compared with those from control animals. As expected, the number of foci was significantly increased in positive controls which were initiated with diethylnitrosamine.

CONCLUSIONS

Iron potentiated the cytotoxic effects of ethanol, resulting in increased serum aminotransferase activities and decreased hepatic contents of ubiquinol. However, the combination of iron and ethanol did not exert genotoxic effects detectable as enhanced hepatic levels of 8-oxo-2'-deoxyguanosine, or increased formation of preneoplastic, glutathione S-transferase 7,7-positive lesions in the Solt & Farber model of chemical hepatocarcinogenesis.

Hepatotoxicity induced by iron overload and alcohol. Studies on the role of chelatable iron, cytochrome P450 2E1 and lipid peroxidation

BACKGROUND/AIMS

Clinical experience and studies with experimental animal models indicate a synergistic hepatotoxic effect of dietary iron overload and chronic alcohol ingestion. In order to elucidate the mechanism underlying this synergism, we examined the hepatic levels of ethanol-inducible cytochrome P450 2E1, glutathione and malondialdehyde, and the effect of iron chelation with desferrioxamine, in livers from rats treated with iron and/or ethanol.

METHODS

Animals received diets with or without 2.5-3% carbonyl iron for 6-9 weeks, followed by an ethanol-containing diet or a liquid control diet for 5-9 weeks. Desferrioxamine was administered subcutaneously with mini-osmotic pumps. Alanine aminotransferase activity in serum and hepatic contents of glutathione and malondialdehyde were determined. The hepatic level of cytochrome P450 2E1 was determined with Western Blotting using a specific polyclonal antibody.

RESULTS

The combination of iron and alcohol led to a marked increase in serum alanine aminotransferase activity as compared with all other treatment groups, and iron chelation with desferrioxamine reversed these increases. Treatment with alcohol alone led to slightly increased aminotransferases compared with controls. The level of cytochrome P450 2E1 was significantly elevated in microsomes isolated from ethanol-treated rats, but neither additional iron supplementation nor desferrioxamine influenced this level significantly. Glutathione contents were increased in the livers of animals treated with iron and/or ethanol. Malondialdehyde values were increased in iron-treated animals, whereas neither ethanol nor desferrioxamine altered malondialdehyde levels significantly.

CONCLUSIONS

The toxic effects exerted by the combination of iron overload and chronic ethanol feeding on rat liver are dependent on a pool of chelatable iron. The hepatic level of cytochrome P450 2E1 is markedly induced by ethanol but not further altered by iron overload. Neither increased lipid peroxidation nor depletion of hepatic glutathione levels can explain the synergistic hepatotoxic effects of iron and ethanol in this model.

Assessment of iron status in association with excess alcohol consumption

Biochemical evidence of iron overload (transferrin saturation greater than 60% and/or serum ferritin concentration greater than 1000 micrograms/L) was observed in 16% of patients admitted to an alcohol withdrawal unit. No subjects in an age and sex matched control group showed such biochemical changes. Whilst changes in serum ferritin concentration closely correlated with aspartate aminotransferase activity and could be explained by alcohol induced liver damage, the increased transferrin saturation was not similarly explained. In nine patients withdrawal of alcohol resulted in a decrease in transferrin saturation and serum ferritin, the former due to a reduction in serum iron concentration. In patients with high alcohol intake biochemical measures of iron status may be misleading and a decrease in both transferrin saturation and serum ferritin concentration after withdrawal of alcohol may help to rule out the possible diagnosis of hereditary haemochromatosis.

A long-term study of the interaction between iron and alcohol in an animal model of iron overload

BACKGROUND/AIMS

The hypothesis that chronic alcohol ingestion potentiates iron-associated liver injury was investigated in the 'carbonyl iron-overload rat model'.

METHODS

Newborn male and female Wistar-Furth rats (seven per group) were used to investigate iron-alcohol interaction over a 26-week period. Groups 1 and 2 were iron loaded from birth, while the others received normal diet. At 10 weeks all rats commenced Lieber-DeCarli liquid diet; additional treatments were: group 1 6 g carbonyl iron/1000 ml diet plus alcohol; group 2 carbonyl iron in the liquid diet; group 3 alcohol in the liquid diet; group 4, the controls, received liquid diet only.

RESULTS

This study confirmed our previous observation that iron-loading from birth resulted in grade III-IV siderosis, in both male and female rats, and caused fibrosis associated with periportal macrophages. Alcohol-feeding, in addition to iron-feeding for 26 weeks significantly lowered the hepatic iron concentration in both male and female rats compared to those fed iron only (p < 0.05). Alcohol feeding did increase hepatic fibrosis in the iron-loaded animals. However, serum alanine aminotransferase activity was significantly higher in the iron-alcohol group than in the other groups (p < 0.05).

CONCLUSIONS

Thus, contrary to expectation, chronic alcohol feeding failed to potentiate hepatic fibrosis in iron-overloaded rats, although there was rather more hepatocyte necrosis, and the serum alanine aminotransferase activity was significantly higher in the iron-alcohol group than in the other groups.

The effect of iron overload and iron reductive treatment on the serum concentration of carbohydrate-deficient transferrin

The concentration of carbohydrate-deficient transferrin in serum (CDT) has been used as a reliable indicator of recent alcohol consumption. We have investigated the utility of this laboratory test in 20 patients with hereditary haemochromatosis (HH) by simultaneous evaluation of serum concentrations of liver transaminases, gamma-glutamyl transpeptidase, iron, transferrin and assessment of the liver iron concentration by magnetic resonance imaging. 11 patients were re-examined during iron depletion with phlebotomies. In all 11 patients intensive but not maintenance iron removal was associated with an increase in serum CDT, in three patients even to levels above the reference range. The mean serum CDT increased from 8.5 (SD 2.2) U/l to 16.6 (SD 7.2) U/l (P < 0.001). Iron mobilization from the liver was found particularly responsible for the increase in serum CDT. Independent of this finding we found a significant semi-logarithmic correlation (r = -0.77, P = 0.009) between the MRI determined liver iron concentration and serum CDT in the patients not on iron depletion. Our findings indicate that the utility of serum CDT as a measure of alcohol consumption in patients with HH may be compromised, especially during intensive iron depletion.

Ethanol-induced changes in membrane ATPases: inhibition by iron chelation

The effect of chronic ethanol intake, with and without an iron chelator, on the activity of rat membrane ATPases was investigated. Using the intragastric feeding model, male Wistar rats (250 g) were fed a liquid diet and ethanol for 1 month. In control pair-fed animals, ethanol was isocalorically replaced by dextrose. In addition to the above groups, two groups of animals (dextrose or ethanol-fed) also received an oral iron chelator (1,2-dimethyl-3-hydroxypyrid-4-one, L1) (25 mg/kg/day for 30 days). The blood ethanol levels were maintained between 150 and 300 mg/dL. Red cells were washed immediately with ice-cold saline, membranes were prepared, and ATPases were measured. The mean Ca2+ pump ATPase in animals fed ethanol was lower than in dextrose-fed controls. In contrast, Na+/K+ pump ATPase was enhanced following chronic ethanol treatment. The addition of L1 to the diet prevented the changes in both the Ca(2+)-ATPase and Na+/K(+)-ATPase in ethanol-fed rats. Although the exact mechanism for the prevention of changes in ATPase activity by L1 is unknown, it is not a result of non-specific interaction between the chelator and membranes. Incubation of purified membranes with different concentrations of L1 for 60 min at 37 degrees had no effect on the activity of the ATPase. In conclusion, chronic intake of ethanol specifically inhibited Ca2+ pump ATPase and enhanced Na+/K(+)-ATPase in rat red blood cell membranes. The iron chelator, L1, corrected both of these ethanol-induced changes.

Pathophysiology of iron toxicity

There are several inherited and acquired disorders that can result in chronic iron overload in humans, and the major clinical consequences are hepatic fibrosis, cirrhosis, hepatocellular cancer, cardiac disease, and diabetes. It is clear that lipid peroxidation occurs in experimental iron overload if sufficiently high levels of iron within hepatocytes are achieved. Lipid peroxidation is associated with hepatic mitochondrial and microsomal dysfunction in experimental iron overload, and lipid peroxidation may underlie the increased lysosomal fragility that has been detected in liver samples from both iron-loaded human subjects and experimental animals. Reduced cellular ATP levels, impaired cellular calcium homeostasis, and damage to DNA may all contribute to hepatocellular injury in iron overload. Long-term dietary iron overload in rats can lead to increased collagen gene expression and hepatic fibrosis, perhaps due to activation of hepatic lipocytes. The mechanisms whereby lipocytes are activated in iron overload remain to be elucidated; possible mediators include aldehydic products of iron-induced lipid peroxidation produced in hepatocytes, tissue ferritin, and/or cytokines released by activated Kupffer cells.