Insulin resistance-associated hepatic iron overload

Interaction of non-alcoholic fatty liver disease with other liver diseases

Obesity-related steatosis is an increasingly common histological finding in liver biopsies and may co-exist with other chronic liver diseases. Although non-alcoholic fatty liver disease (NAFLD) without true steatohepatitis is generally a benign condition, when another liver disease is present, steatosis may exacerbate the liver damage. In this review, we discuss the interaction of obesity-related steatosis with chronic hepatitis C, alcoholic liver disease, disorders of hepatic iron storage and drug-induced liver disease. The role of weight reduction in minimizing liver injury in patients with chronic hepatitis C is discussed. Finally, we discuss the problems associated with orthotopic liver transplantation for patients with NAFLD.

Iron activates NF-kappaB in Kupffer cells

Iron exacerbates various types of liver injury in which nuclear factor (NF)-kappaB-driven genes are implicated. This study tested a hypothesis that iron directly elicits the signaling required for activation of NF-kappaB and stimulation of tumor necrosis factor (TNF)-alpha gene expression in Kupffer cells. Addition of Fe2+ but not Fe3+ (approximately 5-50 microM) to cultured rat Kupffer cells increased TNF-alpha release and TNF-alpha promoter activity in a NF-kappaB-dependent manner. Cu+ but not Cu2+ stimulated TNF-alpha protein release and promoter activity but with less potency. Fe2+ caused a disappearance of the cytosolic inhibitor kappaBalpha, a concomitant increase in nuclear p65 protein, and increased DNA binding of p50/p50 and p65/p50 without affecting activator protein-1 binding. Addition of Fe2+ to the cells resulted in an increase in electron paramagnetic resonance-detectable.OH peaking at 15 min, preceding activation of NF-kappaB but coinciding with activation of inhibitor kappaB kinase (IKK) but not c-Jun NH2-terminal kinase. In conclusion, Fe2+ serves as a direct agonist to activate IKK, NF-kappaB, and TNF-alpha promoter activity and to induce the release of TNF-alpha protein by cultured Kupffer cells in a redox status-dependent manner. We propose that this finding offers a molecular basis for iron-mediated accentuation of TNF-alpha-dependent liver injury.

Genetic Covariation between Serum γ-Glutamyltransferase Activity and Cardiovascular Risk Factors

Background: Several studies have shown that variation in serum γ-glutamyltransferase (GGT) in the population is associated with risk of death or development of cardiovascular disease, type 2 diabetes, stroke, or hypertension. This association is only partly explained by associations between GGT and recognized risk factors. Our aim was to estimate the relative importance of genetic and environmental sources of variation in GGT as well as genetic and environmental sources of covariation between GGT and other liver enzymes and markers of cardiovascular risk in adult twin pairs.

Methods: We recruited 1134 men and 2241 women through the Australian Twin Registry. Data were collected through mailed questionnaires, telephone interviews, and by analysis of blood samples. Sources of variation in GGT, alanine aminotransferase (ALT), and aspartate aminotransferase (AST) and of covariation between GGT and cardiovascular risk factors were assessed by maximum-likelihood model-fitting.

Results: Serum GGT, ALT, and AST were affected by additive genetic and nonshared environmental factors, with heritabilities estimated at 0.52, 0.48, and 0.32, respectively. One-half of the genetic variance in GGT was shared with ALT, AST, or both. There were highly significant correlations between GGT and body mass index; serum lipids, lipoproteins, glucose, and insulin; and blood pressure. These correlations were more attributable to genes that affect both GGT and known cardiovascular risk factors than to environmental factors.

Conclusions: Variation in serum enzymes that reflect liver function showed significant genetic effects, and there was evidence that both genetic and environmental factors that affect these enzymes can also affect cardiovascular risk.

Management of nonalcoholic steatohepatitis: an analytic review

Nonalcoholic steatohepatitis (NASH) is a metabolic disorder of the liver, which, although usually relatively mild, may in some cause fibrosis, cirrhosis, and premature death resulting from liver failure. Its prevalence is increasing, and it is probably underestimated as a cause for cirrhosis. The need for an effective treatment is clear and urgent. Although several small, pilot, and randomized studies have been reported, large-scale studies are yet to be performed in patients with NASH. The aim of therapy is to intervene early in patients at risk of progression of liver disease. In this review, we summarize the extant literature on the management of NASH and discuss the potential future therapies and prophylactic recommendations in patients with NASH.

HFE based re-evaluation of heterozygous hemochromatosis

Homozygosity for the C282Y mutation in the HFE gene is strongly associated with hereditary hemochromatosis. More than one subject out of 10 in the general population is a heterozygote for the C282Y mutation. In this study, we address whether or not conclusions drawn from HLA-based family studies regarding the expression of heterozygous hemochromatosis are applicable to C282Y heterozygotes. The correlation between HLA-inferred and HFE genotypes and the variation of serum iron tests according to HFE genotype and other factors were studied in persons from well-characterized hemochromatosis pedigrees. Subjects were tested for both C282Y and H63D mutations. The following factors were studied: age, sex, alcohol consumption, body mass index, liver function tests, serum lipids and glucose, serum iron, transferrin saturation, and ferritin. HLA-inferred heterozygotes were C282Y heterozygotes in only 70% and compound heterozygotes (i.e., heterozygotes for both C282Y and H63D) in 20%. C282Y heterozygotes did not differ from wild type homozygotes in terms of serum iron tests. Only compound heterozygotes presented with slightly increased transferrin saturation. On the other hand, increased serum ferritin was strongly associated with overweight or lipidic or glucose abnormalities. C282Y heterozygotes selected from family studies do not have greater serum iron tests than wild type homozygotes, except for compound heterozygotes, and therefore should not require special followup. The discovery of abnormal iron tests in a C282Y heterozygote should lead to workup for other causes of iron overload.

Increased serum ferritin is common in men with essential hypertension

OBJECTIVES

Insulin-resistance-associated hepatic iron overload syndrome (IRHIO) is characterized by high serum ferritin and presence of metabolic alterations that are part of insulin-resistance syndrome (IRS). Thus, clinical conditions characterized by a high prevalence of IRS may also be characterized by a high prevalence of IRHIO.

DESIGN AND METHODS

We studied 88 consecutive patients with essential hypertension, 62 patients with IRHIO and 102 healthy normotensive controls. Hemochromatosis, other conditions able to induce secondary iron overload or serum ferritin increase unrelated to body iron stores were excluded. Iron indices, metabolic profiles and hepatic tests in hypertensive with or without increased serum ferritin and in IRHIO with and without hypertension were studied. Metabolic variables, serum iron indices, liver function tests and hepatic ultrasound data were analysed. Data were compared by non-parametric tests.

RESULTS

In men with hypertension, increased serum ferritin was more frequent than in controls (21 versus 0%, P = 0.001). Hypertensive men with increased serum ferritin had more frequent and pronounced metabolic alterations than those with normal serum ferritin, the metabolic abnormalities and serum ferritin being frequently positively correlated. In hypertensive men with increased serum ferritin, metabolic and iron data were similar to those of IRHIO patients with hypertension.

CONCLUSIONS

In males, hypertension is characterized by a higher prevalence of increased iron stores and metabolic abnormalities that are part of the IRHIO syndrome. This finding may have clinical implications due to the increased risk of IRHIO patients to develop hepatic cirrhosis and also for the role of iron in early atherogenesis.

Cross-talk between iron metabolism and diabetes

Emerging scientific evidence has disclosed unsuspected influences between iron metabolism and type 2 diabetes. The relationship is bi-directional--iron affects glucose metabolism, and glucose metabolism impinges on several iron metabolic pathways. Oxidative stress and inflammatory cytokines influence these relationships, amplifying and potentiating the initiated events. The clinical impact of these interactions depends on both the genetic predisposition and the time frame in which this network of closely related signals acts. In recent years, increased iron stores have been found to predict the development of type 2 diabetes while iron depletion was protective. Iron-induced damage might also modulate the development of chronic diabetes complications. Iron depletion has been demonstrated to be beneficial in coronary artery responses, endothelial dysfunction, insulin secretion, insulin action, and metabolic control in type 2 diabetes. Here, we show that iron modulates insulin action in healthy individuals and in patients with type 2 diabetes. The extent of this influence should be tested in large-scale clinical trials, searching for the usefulness and cost-effectiveness of therapeutic measures that decrease iron toxicity. The study of individual susceptibility and of the mechanisms that influence tissue iron deposition and damage are proposed to be valuable in anticipating and treating diabetes complications.

Islet hyperplasia in callitrichids

Five callitrichids (three common marmosets -Callithrix jacchus -, a black tufted-eared marmoset -C. penicillata-, and a saddle-back tamarin -Saguinus fuscicollis) were diagnosed with islet hyperplasia by histopathology and immunohistochemistry. All were privately-owned, unrelated callitrichids ranging from 2- to 4-year-old. Relevant findings were anorexia (3/5), vomiting (2/5), ptyalism (1/5), polyuria/polydipsia (1/5), respiratory distress (1/5), hyperglycemia (2/3) and glycosuria (1/1); hyperglycemia and glycosuria were associated with pregnancy in a common marmoset and resolved after reducing simple carbohydrates in diet. All five animals died, three of them after few premonitory signs; in two cases, other concurrent diseases unrelated to islet hyperplasia were considered the cause of death. Additional animals from two facilities had high weight (4), physical obesity (3), polyuria/polydipsia/polyphagia/uriposia (1), hyperglycemia (1), and/or glycosuria (2). Pathologic findings in the deceased callitrichids were: islet hyperplasia (5/5); hemosiderosis (5/5); lipomatosis (4/5) of several tissues (atria, 3/5; pancreas, gall bladder, intestine, esophagus, and thyroid, 2/5; liver, 1/5); pancreatic necrosis or steatonecrosis, and/or acute pancreatitis (3/5); and vacuolation of hepatocytes and renal tubular cells most likely consistent with hepatorenal lipidosis (2/5). The islets of Langerhans were more numerous and larger than in a control, and morphologically normal in all cases, except in a common marmoset that had a few cells with a foamy cytoplasm and shrunken hyperchromatic or picknotic nucleus. Insulin (5/5), glucagon (3/5), and somatostatin (3/5) immunohistochemistry revealed that most cells stained positively for insulin diffusely in their cytoplasm (5/5) (staining restricted to the vascular pole of b-cells in the control). These findings suggest that obesity, insulin resistance and/or type II diabetes may be implicated and thus a prospective study on these diseases in callitrichids is necessary to determine their etiopathogenesis.

HFE genotype frequencies in consecutive reference laboratory specimens: comparisons among referral sources and association with initial diagnosis

We quantified HFE genotype frequencies in specimens submitted by physicians grouped by specialty and determined associations of genotypes with initial diagnosis based on phenotyping in patients evaluated at an iron disorders center. Of 526 specimens (519 from Alabama), these "typical" hemochromatosis-associated genotypes were detected: 85 C282Y/C282Y, 50 C282Y/H63D, and 27 H63D/H63D. Respective frequencies of C282Y/C282Y in specimens from an iron disorders center (n = 156), gastroenterologists (n = 147), hematologists/medical oncologists (n = 85), liver transplant surgeons (n = 11), endocrinologists and rheumatologists (n = 9), and "other sources" (n = 7) were greater (p < 0.05) than in population controls. In 44 patients from an iron disorders center initially diagnosed as "presumed hemochromatosis," 27 (61.4%) had C282Y/C282Y, 10 (22.7%) had C282Y/H63D, and 3 (6.8%) had H63D/H63D. C282Y/C282Y was not detected in 48 patients with "abnormality probably not an iron overload disorder." A total of 20.5% of 44 family members of patients had "typical" hemochromatosis-associated HFE genotypes (7.0% controls; p = 0.02). We conclude that most physicians who submitted specimens identify patients by phenotyping who have greater frequencies of "typical" hemochromatosis-associated HFE genotypes than controls, and that HFE mutation testing is useful in detecting hemochromatosis in family members of persons with hemochromatosis or iron overload.

Iron overload disorders

Because hepatic siderosis is a frequent finding, there is a risk of making it trite when elaborating the pathology report. Iron is increasingly considered an important cofactor of morbidity. Its finding in hepatic cells must be recognized, indicated, qualified, quantified, and interpreted. A systematic reasoning based on a strict semiological approach allows for guiding the clinician. Iron overload syndromes do not amount to genetic hemochromatosis only.

Alcoholic and nonalcoholic steatohepatitis

The constellation of histopathologic lesions that characterize alcoholic and nonalcoholic steatohepatitis has been well described and has served as the basis for clinical diagnosis, natural history studies, and experimental models for analyses of etiopathogenesis. The lesions common to both entities include, to varying degrees, steatosis, liver cell ballooning, lobular inflammation with a notable component of polymorphonuclear leukocytes, and a characteristic form of fibrosis that is initially located in the perisinusoidal regions of acinar zone 3. Cirrhosis with or without steatosis or steatohepatitis may occur in both entities. Mallory's hyaline is common but not necessary; megamitochondria and varying amounts of iron may be observed in either process. Hepatocellular carcinoma is a recognized complication of both processes, albeit with greater frequency in the former. Alcoholic hepatitis may present with more severe clinical and histologic manifestations than the nonalcoholic counterpart, including significant morbidity and mortality. The perivenular lesions collectively referred to as sclerosing hyaline necrosis are markers of severity, and are not common in nonalcoholics. In many instances, however, the microscopic lesions of these two processes are similar, likely as a reflection of common pathogenetic pathways, and the distinction between the two is ultimately clinically derived.

Effect of iron depletion in carbohydrate-intolerant patients with clinical evidence of nonalcoholic fatty liver disease

BACKGROUND & AIMS

Increased body iron, genetic hemochromatosis (GH) mutations, and nonalcoholic fatty liver disease (NAFLD) tend to cluster in carbohydrate-intolerant patients. In an attempt to further clarify the interrelationships among these conditions, we studied 42 carbohydrate-intolerant patients who were free of the common GH mutations C282Y and H63D, and had a serum iron saturation lower than 50%.

METHODS

We measured body iron stores, and induced iron depletion to a level of near-iron deficiency (NID) by quantitative phlebotomy.

RESULTS

In the 17 patients with clinical evidence of NAFLD, we could not demonstrate supranormal levels of body iron (1.6 +/- 0.2 vs. 1.4 +/- 0.2 g; P = 0.06). However, at NID, there was a 40%-55% improvement (P = 0.05-0.0001) of both fasting and glucose-stimulated plasma insulin concentrations, and near-normalization of serum alanine aminotransferase activity (from 61 +/- 5 to 32 +/- 2 IU/L; P < 0.001).

CONCLUSIONS

These results reflect the insulin-sparing effect of iron depletion and indicate a key role of iron and hyperinsulinemia in the pathogenesis of NAFLD.

Fasting insulin and uric acid levels but not indices of iron metabolism are independent predictors of non-alcoholic fatty liver disease. A case-control study

BACKGROUND

Non-alcoholic fatty liver disease is a common reason for hepatological consultation and may herald severe hepatic and extra-hepatic disease. The aetiopathogenesis of this condition is an area of increasing interest.

AIM

To evaluate anthropometric and biochemical factors associated to non-alcoholic fatty liver disease in a case-control study. Methods. Demographic and biochemical data of 60 consecutive patients with bright liver absent-to-low alcohol consumption, no evidence of viral, genetic and autoimmune diseases, were compared to those of 60 age- and gender-matched historical controls without fatty liver by univariate and multiple logistic regression analysis.

RESULTS

Patients were more often hypertriglyceridaemic, obese and diabetic than controls (p<.01). Mean values of alanine transaminase, gammaglutamyltranspeptidase, triglycerides, uric acid, fasting and log insulin, transferrin percent saturation and ferritin were significantly higher in the patients, while transferrin and quantitative insulin sensitivity check index, a quantitative insulin sensitivity index, were lower. No iron storage was found in those who underwent liver biopsy At univariate analysis the relative risk for non-alcoholic fatty liver disease significantly increased (p<0. 05) with increasing body mass index, fasting insulin, alanine transaminase, uric acid, triglycerides and gammaglutamyltranspeptidase; it decreased with increasing transferrin and quantitative insulin sensitivity check index. Multiple logistic regression analysis disclosed only fasting insulin and uric acid to be independent predictors of non-alcoholic fatty liver disease (p<0.05).

CONCLUSIONS

Fasting insulin and serum uric acid levels indicating insulin resistance, but not indices of iron overload, are independent predictors of non-alcoholic fatty liver disease.

Non-alcoholic steatohepatitis: clinical significance and pathogenesis

Non-alcoholic steatohepatitis (NASH) is a form of liver disease resembling alcoholic liver disease in a patient who does not consume significant amounts of alcohol. Since its first description in 1980 it has been recognized with increasing frequency. The natural course is relatively benign, but liver cirrhosis. together with all its sequelae, may develop; sometimes liver transplantation is indicated. NASH should probably be regarded as a two-stage acquired metabolic disorder consisting of the development of the insulin resistance syndrome in a patient with pre-existing metabolic abnormalities. The insulin resistance syndrome may well be the most important metabolic abnormality giving rise to hepatic steatosis. The preexisting metabolic abnormalities can be diverse, and may well be multifactorial and/or polymorphogenetic. A steatotic liver may be more susceptible to the deleterious effects of the pre-existing metabolic abnormalities. Pre-existing metabolic abnormalities of particular interest are increased hepatic iron storage and derangements of lipoprotein metabolism. While awaiting the complete resolution of the pathogenesis, current treatment is largely conservative. Every patient should be encouraged to lose weight and to avoid alcohol and other hepatotoxins. In addition, diabetes, lipid abnormalities and increased iron stores should be looked for.

Nonalcoholic steatohepatitis, insulin resistance, and metabolic syndrome: further evidence for an etiologic association

This study aims to determine the presence of the components of the metabolic syndrome in primary nonalcoholic steatohepatitis (NASH) and to assess the role of liver disease in the genesis of peripheral hyperinsulinemia. Nineteen patients (18 men and 1 woman; mean age, +/- SD, 38 +/- 10 years; body mass index [BMI], 26 +/- 2 kg/m(2)) with histologic evidence of NASH were enrolled; 19 age- and sex-matched normal subjects were investigated as controls. Plasma glucose, insulin, and C-peptide levels were measured during an oral glucose tolerance test, and a frequently sampled intravenous glucose tolerance test (FSIGT), analyzed by minimal modeling technique, was performed. Compared with controls, the NASH group had lower insulin sensitivity (3.84 +/- 2.44 vs. 7.48 +/- 3.01 10(-4) x min(-1)/microU/mL; P =.0003) and higher total insulin secretion (21 +/- 13 vs. 10 +/- 3 nmol/L in 240 minutes; P =.001). Hepatic insulin extraction was similar in both groups (69.8% +/- 16.1% vs. 70.2% +/- 18.3%; P =.854). According to the results of the oral glucose tolerance test, no patient was classified as diabetic, 5 were classified as glucose intolerant, and 1 was classified as having impaired fasting glycemia. Nine patients (47%) had at least the 2 minimum criteria required to define the metabolic syndrome according to the European Group for the Study of Insulin Resistance (EGIR). In conclusion, hyperinsulinemia and insulin resistance occur frequently in patients with NASH; these conditions do not stem from a reduced hepatic insulin extraction but from an enhanced pancreatic insulin secretion compensatory to reduced insulin sensitivity. The derangement of insulin regulation, often associated with the metabolic syndrome, may play a causal role in the pathogenesis of NASH.

Tumor necrosis factor alpha promoter polymorphisms and insulin resistance in nonalcoholic fatty liver disease

BACKGROUND & AIMS

Nonalcoholic fatty liver disease, which can range from fatty liver alone to nonalcoholic steatohepatitis and cirrhosis, is related to insulin resistance. Tumor necrosis factor alpha (TNF-alpha) may induce insulin resistance, and polymorphisms of its promoter have been associated with an increased release of this cytokine. We analyzed (1) the prevalence of insulin resistance, (2) the prevalence of the 238 and 308 TNF-alpha polymorphisms, and (3) the relationship among TNF-alpha polymorphisms, insulin resistance, and the occurrence of steatohepatitis in 99 patients with nonalcoholic fatty liver diagnosed by ultrasonography and confirmed by histologic analysis in the 53 who underwent biopsy.

METHODS

Insulin resistance was evaluated by the homeostatic metabolic assessment insulin resistance indices and TNF-alpha polymorphisms by polymerase chain reaction and restriction fragment length polymorphism analysis.

RESULTS

Insulin resistance was detected in almost all of the patients and was more severe in those with steatohepatitis. The prevalence of the 238, but not of the 308, TNF-alpha polymorphism was higher in subjects with nonalcoholic fatty liver than in controls (31% vs. 15%; P < 0.0001), and patients positive for TNF-alpha polymorphisms had higher insulin resistance indices, a higher prevalence of impaired glucose tolerance, and a lower number of associated risk factors for steatosis.

CONCLUSIONS

TNF-alpha polymorphisms could represent a susceptibility genotype for insulin resistance, nonalcoholic fatty liver, and steatohepatitis.

Iron accumulation in the liver of male patients with Wilson's disease

OBJECTIVES

There is accumulating evidence that ceruloplasmin, a copper protein with ferroxidase activity, plays an important role in iron metabolism. The genetic disorder, aceruloplasminemia, can lead to tissue storage of iron as in hemochromatosis. Because most patients with Wilson's disease, a genetic copper toxicosis, have hypoceruloplasminemia, some could be affected by iron overload.

METHODS

Four male patients with Wilson's disease were enrolled in this study of pre- and post-treatment iron metabolism.

RESULTS

Pretreatment copper contents of the liver were high in all four male patients studied as diagnostic of Wilson's disease. Genetic analysis supported their clinical diagnosis of Wilson's disease without a background of hemochromatosis. Pretreatment serum ceruloplasmin levels were <20 mg/dl in all four patients. A standard penicillamine treatment for 3-8.5 yr further decreased their serum ceruloplasmin levels. Post-treatment serum ferroxidase activity was low as was the serum ceruloplasmin protein. Copper contents in the liver decreased after treatment in all subjects. In contrast, nonheme iron in the liver increased during treatment. Pretreatment liver specimens were positive for histochemical iron in two patients, and post-treatment specimens were positive in all four patients. In two patients, serum aminotransferase levels rebounded with elevation of serum ferritin concentration during the treatment period. Subsequent iron reduction by phlebotomy ameliorated their biochemical liver damage.

CONCLUSION

Iron overload related to hypoceruloplasminemia may be clinically important, particularly in male patients with Wilson's disease.

Association of Increased Ferritin with Premature Coronary Stenosis in Men

Background: Body iron status has been implicated in atherosclerotic cardiovascular disease. The main hypothesis is that high iron status is associated with increased oxidation of LDL. We investigated the potential role of ferritin as an additional risk factor promoting atherosclerosis among a young population with coronary artery disease (CAD).

Methods: Four hundred consecutive patients (218 males, 182 females) referred for diagnostic coronary angiography were examined, and risk factors for CAD, lipids, C-reactive protein (CRP), and ferritin concentrations were recorded for all participants.

Results: Ferritin was higher in the male patients with CAD (121 μg/L; range, 56–258 μg/L) than in the men without significant CAD (73 μg/L; range, 32–138 μg/L; P &lt;0.002). Multiple logistic regression analysis, after adjustment for the established coronary risk factors, showed ferritin as an independent discriminating risk factor for CAD (P &lt;0.01). Men in the highest quartile of ferritin had an odds ratio (OR) of 1.62 [95% confidence interval (95% CI), 1.12–2.42; P &lt;0.01] compared with men in the lowest quartile of ferritin. The association between ferritin and CAD was more pronounced in male patients ≤50 years (OR = 2.65; 95% CI, 1.35–5.51; P &lt;0.003). Ferritin was significantly higher in diabetic male patients in comparison with nondiabetic male patients [168 μg/L (range, 74–406 μg/L) vs 106 μg/L (range, 44–221 μg/L), respectively; P &lt;0.002]. No association was observed between ferritin and CAD among the female patients.

Conclusion: Our data suggest that increased ferritin might be an independent predictor of premature CAD in male Iranian patients.

Venesection therapy of insulin resistance-associated hepatic iron overload

BACKGROUND/AIMS

The association of hepatic iron overload with metabolic disorders has been coined as the insulin resistance-associated hepatic iron overload syndrome (IR-HIO).

METHODS

Fifty-six IR-HIO patients were phlebotomized either weekly (n = 14) or bimonthly (n = 42) and compared with C282Y homozygotes and with ten IR-HIO patients treated by a low calorie diet alone.

RESULTS

In venesected patients, the median amount of mobilized iron was 0.6 g in 2.8 months in females and 1.8 g in 5 months in males. Mobilized iron did not differ depending on the frequency of venesections or HFE genotype. When compared with C282Y homozygotes, IR-HIO patients had a similar amount of mobilized iron, but three-fold serum ferritin levels. The presenting symptoms (chronic fatigue and/or polyarthralgias) improved in 6/7 patients. Phlebotomies were well tolerated. In patients treated by a low calorie diet, serum ferritin levels remained stable.

CONCLUSIONS

In IR-HIO patients, body iron stores are significantly increased, overestimated by serum ferritin, not modified by a low calorie diet, and safely removed by phlebotomies. Based on these data and on studies indicating that iron excess is associated with increased risk for hepatic fibrosis, cancer and cardiovascular disorders, venesection therapy can be recommended in IR-HIO patients.

Nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH) is a condition characterized by hepatomegaly, elevated serum aminotransferase levels, and a histologic picture similar to alcoholic hepatitis in the absence of alcohol abuse. Most patients with NASH are obese women, and many have diabetes mellitus, hypercholesterolemia, or hypertriglyceridemia. NASH has also been associated with a number of metabolic conditions, surgical procedures, and drug treatments. Most patients are asymptomatic. The most common sign of NASH is hepatomegaly. Stigmata of chronic liver disease are rare. Laboratory abnormalities include a 2-4-fold elevation of serum aminotransferase levels; other liver function test results are usually normal. Histologically, there is moderate to severe macrovesicular steatosis and lobular hepatitis with necrosis or ballooning degeneration and/or fibrosis. The pathogenesis of NASH is poorly understood, but lipid peroxidation and oxidative stress are the leading culprits. The natural history of NASH is unknown, but NASH seems to be a stable disease in most patients. Treatment of NASH is unproven, but weight reduction is recommended in obese patients. Small pilot studies of several drugs have shown promise, but large randomized clinical trials are awaited. Orthotopic liver transplantation is the treatment of choice for end-stage liver disease secondary to NASH.

Nonalcoholic fatty liver disease: a feature of the metabolic syndrome

Insulin sensitivity (euglycemic clamp, insulin infusion rate: 40 mU. m(-2). min(-1)) was studied in 30 subjects with biopsy-proven nonalcoholic fatty liver disease (NAFLD), normal glucose tolerance, and a BMI <30 kg/m(2). Of those 30 subjects, 9 had pure fatty liver and 21 had evidence of steatohepatitis. In addition, 10 patients with type 2 diabetes under good metabolic control and 10 healthy subjects were studied. Most NAFLD patients had central fat accumulation, increased triglycerides and uric acid, and low HDL cholesterol, irrespective of BMI. Glucose disposal during the clamp was reduced by nearly 50% in NAFLD patients, as well as in patients with normal body weight, to an extent similar to that of the type 2 diabetic patients. Basal free fatty acids were increased, whereas insulin-mediated suppression of lipolysis was less effective (-69% in NAFLD vs. -84% in control subjects; P = 0.003). Postabsorptive hepatic glucose production (HGP), measured by [6,6-(2)H(2)]glucose, was normal. In response to insulin infusion, HGP decreased by only 63% of basal in NAFLD vs. 84% in control subjects (P = 0.002). Compared with type 2 diabetic patients, NAFLD patients were characterized by lower basal HGP, but with similarly reduced insulin-mediated suppression of HGP. There was laboratory evidence of iron overload in many NAFLD patients, but clinical, histological, and biochemical data (including insulin sensitivity) were not correlated with iron status. Four subjects were heterozygous for mutation His63Asp of the HFE gene of familiar hemochromatosis. We concluded that NAFLD, in the presence of normoglycemia and normal or moderately increased body weight, is characterized by clinical and laboratory data similar to those found in diabetes and obesity. NAFLD may be considered an additional feature of the metabolic syndrome, with specific hepatic insulin resistance.

Risk factors for diabetes mellitus and early insulin resistance in chronic hepatitis C

BACKGROUND/AIMS

Our aims were to investigate the host and viral specific factors associated with diabetes mellitus (DM) and insulin resistance in chronic hepatitis C patients.

METHODS

One hundred and three hepatitis C virus (HCV)-infected were studied to assess the effects of HCV genotype, hepatic iron content, steatosis, hepatic fibrosis, body mass index (BMI) and family history of DM on the occurrence of DM. Insulin resistance (HOMA IR) was studied in 81 non-diabetic patients to determine the mechanism associated with insulin resistance in this subgroup.

RESULTS

Sixteen of the 123 were diabetic (13.0%). The variables predictive of DM were METAVIR fibrosis score 4 (OR, 13.16; P = 0.012), family history of diabetes (OR, 16.2; P = 0.0023), BMI (OR, 1.37; P = 0.017) and age (OR, 1.09; P = 0.002). In non-diabetic HCV-infected patients, HOMA-IR of METAVIR fibrosis score 0 and 1 patients were significantly different than score 2 and score 3/4 patients.

CONCLUSIONS

Our findings indicate that older age, obesity, severe liver fibrosis and family history of diabetes help identify those HCV patients who might have potential risk factors for development of DM. We observed that insulin resistance in non-diabetic HCV-infected patients was related to grading of liver fibrosis, and occurs already at an early stage in the course of HCV infection.

Hyperferritinemia, iron overload, and multiple metabolic alterations identify patients at risk for nonalcoholic steatohepatitis

OBJECTIVE

The aim of this study was to define in patients with hyperferritinemia and normal transferrin saturation the relationships among hyperferritinemia, iron overload, HFE gene mutations, the presence of metabolic alterations, and nonalcoholic steatohepatitis (NASH).

METHODS

Forty patients with increased serum ferritin, resistant to dietary restriction and normal transferrin saturation, 90 with ultrasonographic evidence of hepatic steatosis, and 60 obligate heterozygotes for hemochromatosis, all negative for alcohol abuse, hepatitis virus infections, and inflammation were studied. Transferrin saturation, serum ferritin, uric acid, lipids, glucose tolerance, insulin resistance, HFE gene mutations, liver histology, and hepatic iron concentration were analyzed.

RESULTS

Of the 40 patients with hyperferritinemia, 29 (72%) had biochemical metabolic abnormalities, 18 of the 26 examined (69%) had insulin resistance, 26 (65%) had the presence of one of the two HFE gene mutations (normal controls, 33 of 128 [26%], p < 0.0001), and all had increased liver iron concentration. Thirty-one patients (77%) had histology compatible with NASH. At univariate analysis, NASH was significantly associated with the presence of metabolic alterations, the C282Y mutation, and severity of fibrosis. At multivariate analysis, NASH was associated with the coexistence of multiple metabolic alterations (odds ratio = 5.2, 95% CI = 0.95-28.7). The risk of having NASH augmented in the presence of higher values of ferritin and liver iron concentration. Among the 90 patients with ultrasonographic evidence of hepatic steatosis, 24 (27%) had increased serum ferritin with normal transferrin saturation, but only six remained hyperferritinemic after dietary restriction.

CONCLUSION

Increased ferritin with normal transferrin saturation is frequently found in patients with hepatic steatosis, but it reflects iron overload only in those patients in whom it persists despite an appropriate diet. The simultaneous disorder of iron and glucose and/or lipid metabolism, in most of the cases associated with insulin resistance, is responsible for persistent hyperferritinemia and identifies patients at risk for NASH.

Insulin resistance in non-alcoholic steatohepatitis

BACKGROUND

Non-alcoholic steatohepatitis is a chronic liver disease that is capable of progressing to end-stage liver disease, but generally has a benign course. Obesity, non-insulin-dependent diabetes mellitus and hyperlipidaemia are the most common associations of the disease.

AIMS

To investigate the insulin resistance in patients with non-alcoholic steatohepatitis who have no other causes of insulin resistance such as obesity, diabetes mellitus, and hyperlipidaemia.

PATIENTS

Thirteen patients (7 male, 6 female) with non-alcoholic steatohepatitis and 12 (6 male, 6 female) healthy volunteers.

METHODS

All patients and healthy volunteers were submitted to biochemical tests and hyperinsulinaemic euglycaemic insulin clamp technique.

RESULTS

Basal insulin levels and C-peptide levels were significantly higher in non-alcoholic steatohepatitis group than in controls (p<0.001 and p<0.001, respectively). Hyperinsulinaemic euglycaemic insulin clamp technique revealed lower glucose utilization in the non-alcoholic steatohepatitis group and the difference was statistically significant (p<0.001).

CONCLUSIONS

Our study revealed marked hyperinsulinaemia and insulin resistance in patients with non-alcoholic steatohepatitis. Hyperinsulinaemia and insulin resistance may contribute to pathogenesis of nonalcoholic steatohepatitis.

Clinical aspects of hemochromatosis

Hemochromatosis is one of the most frequent genetic diseases among the white populations, affecting one in three hundred persons. Its diagnosis has been radically transformed by the discovery of the HFE gene. In a given individual, the diagnosis can, from now on, be ascertained on the sole association of a plasma transferrin saturation (TS) over 45% and homozygosity for the C282Y mutation. Liver biopsy is only required to search for cirrhosis whenever there is hepatomegaly and/or serum ferritin >1000 ng/ml and/or elevated serum AST. Family screening is mandatory, primarily centered on the siblings. The treatment remains based on venesection therapy which improves many features of the disease (one of the most refractory, however, being the joint signs) and permits normal life expectancy provided the diagnosis is established prior to the development of cirrhosis or of insulin-dependent diabetes. In view of the prevalence, the non-invasive diagnosis, the spontaneous severity and the efficacy of a very simple therapy, hemochromatosis should benefit from population screening. This screening could be based, first, on the assessment of transferrin saturation, followed - when elevated - by the search for the C282Y mutation. The discovery of the HFE gene has also paved the road for the individualization of other types of iron overload syndromes which are not HFE-related.

Inherited metabolic disease

This review focuses on two genetic disorders of metal metabolism, genetic hemochromatosis and Wilson disease, and on the most common lysosomal storage disorder, Gaucher disease, for which recombinant enzyme replacement therapy is available. The discovery of the genes for these disorders has led to an explosion of new information about the function of these gene products and the identification of other proteins involved in their metabolism. These discoveries have altered our current diagnostic and therapeutic approaches to these disorders and have furthered our understanding of disease pathophysiology. New modalities being developed for future use include cell transplant and genetic replacement therapies.

The biochemistry of chromium

Chromium has been known to be a micronutrient for mammals for four decades, but progress in elucidating the role of chromium has proceeded slowly. However, recent studies have shed light on a potential role of chromium in maintaining proper carbohydrate and lipid metabolism at a molecular level. The oligopeptide chromodulin binds chromic ions in response to an insulin-mediated chromic ion flux, and the metal-saturated oligopeptide can bind to an insulin-stimulated insulin receptor, activating the receptor's tyrosine kinase activity. Thus, chromodulin appears to play a role in an autoamplification mechanism in insulin signaling. The molecular agent responsible for transporting chromium from mobile pools to insulin-sensitive cells is probably the metal transport protein transferrin. Chromium from the popular dietary supplement chromium picolinate enters cells via a different mechanism. Release of chromium from chromium picolinate for use in cells requires reduction of the chromic center, a process that can lead potentially to the production of harmful hydroxyl radicals.

Clinical Consequences of New Insights in the Pathophysiology of Disorders of Iron and Heme Metabolism

This review examines the clinical consequences for the practicing hematologist of remarkable new insights into the pathophysiology of disorders of iron and heme metabolism. The familiar proteins of iron transport and storage—transferrin, transferrin receptor, and ferritin—have recently been joined by a host of newly identified proteins that play critical roles in the molecular management of iron homeostasis. These include the iron-regulatory proteins (IRP-1 and -2), HFE (the product of the HFE gene that is mutated in most patients with hereditary hemochromatosis), the divalent metal transporter (DMT1), transferrin receptor 2, ceruloplasmin, hephaestin, the “Stimulator of Fe Transport” (SFT), frataxin, ferroportin 1 and others. The growing appreciation of the roles of these newly identified proteins has fundamental implications for the clinical understanding and laboratory evaluation of iron metabolism and its alterations with iron deficiency, iron overload, infection, and inflammation.

In Section I, Dr. Brittenham summarizes current concepts of body and cellular iron supply and storage and reviews new means of evaluating the full range of body iron stores including genetic testing for mutations in the HFE gene, measurement of serum ferritin iron, transferrin receptor, reticulocyte hemoglobin content and measurement of tissue iron by computed tomography, magnetic resonance imaging and magnetic susceptometry using superconducting quantum interference device (SQUID) instrumentation.

In Section II, Dr. Weiss discusses the improved understanding of the molecular mechanisms underlying alterations in iron metabolism due to chronic inflammatory disorders. The anemia of chronic disorders remains the most common form of anemia found in hospitalized patients. The network of interactions that link iron metabolism with cellular immune effector functions involving pro- and anti-inflammatory cytokines, acute phase proteins and oxidative stress is described, with an emphasis on the implications for clinical practice.

In Section III, Dr. Brissot and colleagues discuss how the diagnosis and management of hereditary hemochromatosis has changed following the identification of the gene, HFE, that is mutated in most patients with hereditary hemochromatosis, and the subsequent development of a genotypic test. The current understanding of the molecular effects of HFE mutations, the usefulness of genotypic and phenotypic approaches to screening and diagnosis and recommendations for management are summarized.

Clinical Consequences of New Insights in the Pathophysiology of Disorders of Iron and Heme Metabolism

This review examines the clinical consequences for the practicing hematologist of remarkable new insights into the pathophysiology of disorders of iron and heme metabolism. The familiar proteins of iron transport and storage—transferrin, transferrin receptor, and ferritin—have recently been joined by a host of newly identified proteins that play critical roles in the molecular management of iron homeostasis. These include the iron-regulatory proteins (IRP-1 and -2), HFE (the product of the HFE gene that is mutated in most patients with hereditary hemochromatosis), the divalent metal transporter (DMT1), transferrin receptor 2, ceruloplasmin, hephaestin, the “Stimulator of Fe Transport” (SFT), frataxin, ferroportin 1 and others. The growing appreciation of the roles of these newly identified proteins has fundamental implications for the clinical understanding and laboratory evaluation of iron metabolism and its alterations with iron deficiency, iron overload, infection, and inflammation.

In Section I, Dr. Brittenham summarizes current concepts of body and cellular iron supply and storage and reviews new means of evaluating the full range of body iron stores including genetic testing for mutations in the HFE gene, measurement of serum ferritin iron, transferrin receptor, reticulocyte hemoglobin content and measurement of tissue iron by computed tomography, magnetic resonance imaging and magnetic susceptometry using superconducting quantum interference device (SQUID) instrumentation.

In Section II, Dr. Weiss discusses the improved understanding of the molecular mechanisms underlying alterations in iron metabolism due to chronic inflammatory disorders. The anemia of chronic disorders remains the most common form of anemia found in hospitalized patients. The network of interactions that link iron metabolism with cellular immune effector functions involving pro- and anti-inflammatory cytokines, acute phase proteins and oxidative stress is described, with an emphasis on the implications for clinical practice.

In Section III, Dr. Brissot and colleagues discuss how the diagnosis and management of hereditary hemochromatosis has changed following the identification of the gene, HFE, that is mutated in most patients with hereditary hemochromatosis, and the subsequent development of a genotypic test. The current understanding of the molecular effects of HFE mutations, the usefulness of genotypic and phenotypic approaches to screening and diagnosis and recommendations for management are summarized.