AGA technical review on nonalcoholic fatty liver disease

cDNA microarray analysis of autoimmune hepatitis, primary biliary cirrhosis and consecutive disease manifestation

While autoimmune hepatitis (AIH) and primary biliary cirrhosis (PBC) usually have distinct clinical manifestations, some patients present with features of both conditions. Using cDNA microarrays, we analyzed and compared gene expression profiles in 8 patients with AIH, 9 with PBC, 8 with chronic hepatitis C (CHC), 8 with non-alcoholic steatohepatitis (NASH) and 9 with normal livers. We subsequently applied this method to a tissue sample from a 61-year-old woman with overlapping features of both AIH and PBC. A 61-year-old woman was admitted to our hospital for evaluation of elevated serum alkaline phosphatase. A liver biopsy showed accumulation of mononuclear cells around the bile duct cells, a feature characteristic of chronic non-suppurative destructive cholangitis (CNSDC). Three years later, her serum alanine aminotransferase (ALT) level had increased, and a liver biopsy demonstrated evidence of a severe form of hepatitis. A cDNA microarray analysis of both biopsies identified the molecular events associated with her altered histology. The expression profile of this patient, which was originally different from that of the other PBC patients, changed to an AIH pattern. Our results suggest that this patient has characteristics of both AIH and PBC.

Prevalence of and risk factors for fatty liver in a general population of Shanghai, China

BACKGROUND/AIMS

To determine the prevalence and risk factors of fatty liver (FL) among Shanghai adults.

METHODS

A cross-sectional ultrasonographic survey with randomized multistage stratified cluster sampling was used.

RESULTS

The study included 3175 subjects (1218 men) with a mean age of 52 years. FL was found in 661 (20.82%) subjects. After adjustment by age and sex, FL prevalence was found to be 17.29%, and the prevalences of alcoholic, suspected alcoholic and nonalcoholic FL were determined to be 0.79, 1.15 and 15.35%, respectively. Generally, age, body mass index (BMI), waist circumference, blood pressure, and the prevalences of obesity, diabetes, hypertension and dyslipidemia were all significantly higher in FL patients than in controls; In contrast, the levels of high-density-lipoprotein cholesterol (HDL-C), education and physical activity were markedly lower. Multiple regression analyses showed that only nine factors (male, educational level, waist circumference, BMI, HDL-C, triglyceride, fasting plasma glucose, diabetes and hypertension) were closely related to FL. In excessive drinkers, obesity increased the risk for FL by 4.8-fold, but excessive drinking was associated with only a 1.5-fold increased risk in obese subjects.

CONCLUSIONS

FL in Shanghai is highly prevalent and mainly related to multiple metabolic disorders.

Esteatohepatitis no alcohólica asociada a hiperplasia estromal ovárica

Alterations in liver function tests have previously been reported in patients with ovarian disease. We report the case of a woman with prolonged hypertransaminasemia, significant hirsutism and android phenotype who was diagnosed with nonalcoholic steatohepatitis and ovarian stromal hyperplasia.

Spectrum of NAFLD and diagnostic implications of the proposed new normal range for serum ALT in obese women

The upper limit of normal for ALT activity has been recommended to be lowered to < or = 30 U/L in men and < or = 19 U/L in women. These changes have been suggested to be diagnostically useful in subjects with nonalcoholic fatty liver disease (NAFLD). Our aim was to investigate the prevalence and spectrum of NAFLD with regard to the new ALT guidelines in 233 women with class II/III obesity. We compared our prior reference range for ALT (ULN < or = 30 U/L in women) with the new standard. Our study demonstrates that only 86 patients (36.9%) would be classified as having normal ALT levels compared with 169 patients (72.5%) by the new and old standards, respectively. In patients with normal ALT activity (new vs. old standard), the prevalence of fatty liver (FL: 39.5% vs 40.2%), portal fibrosis, and steatosis (IPF: 37.2% vs. 33.7%) and nonalcoholic steatohepatitis (NASH: 23.3% vs. 26%) were similar. In comparison, newly defined patients with elevated ALT levels (>19 U/L) demonstrated an increased prevalence of FL (36%) and IPF (11.6%) but a 23.8% decrease in the prevalence of NASH as compared with the old standard. The sensitivity and specificity for NASH were 42% and 80% (ALT > 30 U/L) compared with 74% and 42% (ALT > 19 U/L). In conclusion, a significant increase in the prevalence of FL and IPF is detected in subjects with elevated ALT levels with the application of the new standard. However, the diagnostic utility for ALT to identify NASH or IPF remains poor, and significant healthcare expenditures may be incurred if this standard is adopted.

Endothelial dysfunction and cardiovascular risk profile in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is consistently associated with features of the metabolic syndrome, a condition carrying a high risk of cardiovascular events. We measured the vasodilatory response of the brachial artery in response to ischemia (a test of endothelial function) (FMV) as well as cardiovascular risk profile in 52 NAFLD cases and 28 age- and sex-matched controls. The 10-year risk of coronary events was calculated according to the Framingham equation and the scores derived from the PROCAM study and NCEP-ATPIII proposals. FMV was 6.33% +/- 5.93% in NAFLD versus 12.22% +/- 5.05% in controls (P < .0001), and higher in pure fatty liver (9.93%) compared with nonalcoholic steatohepatitis (4.94%) (P = .010). No differences were observed in flow-independent vasodilation (response to sublingual nitroglycerin). Percent FMV was negatively associated with insulin resistance (homeostasis model assessment) in the whole population (r = -0.243; P = .030). In logistic regression analysis, NAFLD was associated with a percent FMV in the lower tertile (OR, 6.7; 95% CI, 1.26-36.1), after adjustment for age, sex, body mass index, and insulin resistance. Among NAFLD patients, low FMV was associated with nonalcoholic steatohepatitis (adjusted OR, 6.8; 95% CI, 1.2-40.2). The 10-year probability of cardiovascular events was moderately increased in NAFLD, and particularly in nonalcoholic steatohepatitis. In conclusion, our study provides evidence of endothelial dysfunction and increased risk of cardiovascular events in NAFLD. The risk of advanced liver disease is well recognized in NAFLD patients, but the large majority of cases might experience cardiovascular disease in the long term, indirectly limiting the burden of liver failure.

Gallstone disease in non-alcoholic fatty liver: prevalence and associated factors

BACKGROUND

Insulin resistance is a risk factors for non-alcoholic fatty liver disease (NAFLD) and for gallstone disease (GD). Aims of the present study were to assess the prevalence of and factors associated with GD in unselected patients with NAFLD.

METHODS

A total of 161 consecutive patients with NAFLD diagnosed through compatible ultrasonography in the absence of known etiologies of liver disease (in all patients) and/or confirmed histologically (in 61 patients), was studied. Gallstone disease was diagnosed through ultrasound scanning or on the basis of previous cholecystectomy. Anthropometric and biochemical variables and concurrent diseases were compared in 32 NAFLD-GD patients and in 129 NAFLD patients without GD (controls) according to gender.

RESULTS

The overall prevalence of GD was 19.88%, higher in female patients (P < 0.05), who were older (P < 001). The overall percentage of GD increased with age (P < 0.05). The GD patients had higher uric acid (men), total cholesterol and apolipoprotein B (apo-B) serum concentrations (women; P < 0.05); women also had a higher prevalence of hypertriglyceridemia (P < 0.05). The age-corrected odds ratio of having GD by tertiles increased significantly with increasing uric acid (men) and with increasing total cholesterol, triglycerides and apo-B (women). At univariate continuous analysis GD was associated with insulin 120 min and uric acid in male patients; and with body mass index, insulin 120 min, apo-B, total cholesterol and triglycerides in female patients. On multivariate analysis it was found that among these factors only uric acid in men and apo-B in women were independently associated with GD in NAFLD.

CONCLUSIONS

The prevalence of GD in NAFLD is more elevated than reported in the general population. The factors independently associated with GD in NAFLD are different from those reported in the general population and vary according to the gender.

Hepatocyte Mitochondrial Injury and the Change of Adenosine Triphosphate Storage in Rat Nonalcoholic Steatohepatitis

AIM: To investigate the mitochondrial injury and change in adenosine triphosphate (ATP) storage in a rat model of nonalcoholic steatohepatitis (NASH) induced by fat-rich diet.

METHODS: Seventy-two male SD rats were randomly divided into two groups. The control group (n = 24) was fed with normal diet; the model group (n = 48) was fed with fat-rich diet, which is consisted of 10% lard oil + 2% cholesterol. 6 or 12 rats were sacrificed at the 8^th, 12^th, 16^th and 24^th wk of the experiment. Serum biochemical parameters were measured by a commercial laboratory. The hepatic histologic change was evaluated by light microscopy and transmission electron microscopy. The ATP content was measured by luciferin-luciferase method.

RESULTS: Simple fatty liver was observed in the model group at the 8^th wk. From the 12^th wk to 24^th wk, the liver gradually progressed to steatohepatitis. The ATP content of the liver was reduced in the model group compared with normal group at the 16^th wk [(2.97±0.48)10^-8 μmol/g vs (2.25±0.55)10^-8 μmol/g, P = 0.0 361, t = 2.354] and the 24^th wk [(2.97±0.48)10^-8 μmol/g vs (1.99±0.66)10^-8 μmol/g, P = 0.0 053, t = 3.439]. Markedly abnormal morphology was observed in the hepatocyte mitochondria in model group, including swelling, rounding, loss of cristae, and stacks of intramitochondrial paracrystalline inclusion bodies.

CONCLUSION: The hepatocytic mitochondria in NASH were injured and the storage of ATP was reduced, which may contribute to the pathogenesis of NASH.

Sources of fatty acids stored in liver and secreted via lipoproteins in patients with nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is characterized by the accumulation of excess liver triacylglycerol (TAG), inflammation, and liver damage. The goal of the present study was to directly quantify the biological sources of hepatic and plasma lipoprotein TAG in NAFLD. Patients (5 male and 4 female; 44 +/- 10 years of age) scheduled for a medically indicated liver biopsy were infused with and orally fed stable isotopes for 4 days to label and track serum nonesterified fatty acids (NEFAs), dietary fatty acids, and those derived from the de novo lipogenesis (DNL) pathway, present in liver tissue and lipoprotein TAG. Hepatic and lipoprotein TAG fatty acids were analyzed by gas chromatography/mass spectrometry. NAFLD patients were obese, with fasting hypertriglyceridemia and hyperinsulinemia. Of the TAG accounted for in liver, 59.0% +/- 9.9% of TAG arose from NEFAs; 26.1% +/- 6.7%, from DNL; and 14.9% +/- 7.0%, from the diet. The pattern of labeling in VLDL was similar to that in liver, and throughout the 4 days of labeling, the liver demonstrated reciprocal use of adipose and dietary fatty acids. DNL was elevated in the fasting state and demonstrated no diurnal variation. These quantitative metabolic data document that both elevated peripheral fatty acids and DNL contribute to the accumulation of hepatic and lipoprotein fat in NAFLD.

Sources of fatty acids stored in liver and secreted via lipoproteins in patients with nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is characterized by the accumulation of excess liver triacylglycerol (TAG), inflammation, and liver damage. The goal of the present study was to directly quantify the biological sources of hepatic and plasma lipoprotein TAG in NAFLD. Patients (5 male and 4 female; 44 +/- 10 years of age) scheduled for a medically indicated liver biopsy were infused with and orally fed stable isotopes for 4 days to label and track serum nonesterified fatty acids (NEFAs), dietary fatty acids, and those derived from the de novo lipogenesis (DNL) pathway, present in liver tissue and lipoprotein TAG. Hepatic and lipoprotein TAG fatty acids were analyzed by gas chromatography/mass spectrometry. NAFLD patients were obese, with fasting hypertriglyceridemia and hyperinsulinemia. Of the TAG accounted for in liver, 59.0% +/- 9.9% of TAG arose from NEFAs; 26.1% +/- 6.7%, from DNL; and 14.9% +/- 7.0%, from the diet. The pattern of labeling in VLDL was similar to that in liver, and throughout the 4 days of labeling, the liver demonstrated reciprocal use of adipose and dietary fatty acids. DNL was elevated in the fasting state and demonstrated no diurnal variation. These quantitative metabolic data document that both elevated peripheral fatty acids and DNL contribute to the accumulation of hepatic and lipoprotein fat in NAFLD.

Prevalence of and risk factors for nonalcoholic fatty liver disease: the Dionysos nutrition and liver study

The prevalence of and the risk factors for fatty liver have not undergone a formal evaluation in a representative sample of the general population. We therefore performed a cross-sectional study in the town of Campogalliano (Modena, Italy), within the context of the Dionysos Project. Of 5,780 eligible persons aged 18 to 75 years, 3,345 (58%) agreed to participate in the study. Subjects with suspected liver disease (SLD), defined on the basis of elevated serum alanine aminotransferase (ALT) and gamma-glutamyl-transferase (GGT) activity, hepatitis B surface antigen (HBsAg), or hepatitis C virus (HCV)-RNA positivity, were matched with randomly selected subjects of the same age and sex without SLD. A total of 311 subjects with and 287 without SLD underwent a detailed clinical, laboratory, and anthropometrical evaluation. Fatty liver was diagnosed by ultrasonography, and alcohol intake was assessed by using a 7-day diary. Multinomial logistic regression was used to detect risk factors for normal liver versus nonalcoholic fatty liver disease (NAFLD) and for alcoholic fatty liver (AFLD) versus NAFLD. The prevalence of NAFLD was similar in subjects with and without SLD (25 vs. 20%, P = .203). At multivariable analysis, normal liver was more likely than NAFLD in older subjects and less likely in the presence of obesity, hyperglycemia, hyperinsulinemia, hypertriglyceridemia, and systolic hypertension; AFLD was more likely than NAFLD in older subjects, males, and in the presence of elevated GGT and hypertriglyceridemia, and less likely in the presence of obesity and hyperglycemia. In conclusion, NAFLD is highly prevalent in the general population, is not associated with SLD, but is associated with many features of the metabolic syndrome.

Semiquantitative evaluation overestimates the degree of steatosis in liver biopsies: a comparison to stereological point counting

The degree of steatosis in liver biopsies is usually assessed by a morphological semiquantitative approach in which the histopathologist uses a four-graded scale: 0-3 or none, slight, moderate and severe. Scores 1-3 are considered to correspond to fat deposition in <33, 33-66 and >66% of the hepatocytes. There is a considerable inter- and intra-individual variation in such scoring methods and a more standardized and quantitative approach is preferable. In the present study, we compare the semiquantitative technique with the stereological point counting method in the assessment of hepatic steatosis. A total of 75 archived liver needle biopsies were used. They were selected according to the original routine diagnosis of slight, moderate or severe steatosis. In all, 10 randomly selected images from each biopsy were digitized into a computer, a point grid lattice was superimposed and the number of hits on fat globules was counted. A pathologist scored the specimens in a four-graded scale as described above. The mean liver biopsy area (volume) with fat in hepatocytes was 2.2% for grade 1, 9.2% for grade 2 and 23.1% for grade 3. The kappa value for the semiquantitative estimates was 0.71 for the unweigthed kappa and 0.87 for weighted kappa. The intraclass correlation coefficient (ICC) was 0.99 for images counted twice and 0.95 when two sets of images were captured from the same biopsy. These ICCs indicate excellent agreement and above that of the semiquantitative estimates. In conclusion, the area/volume of fat content of the hepatocytes is greatly overemphasized in semiquantitative estimation. Furthermore, the point counting technique has a better reproducibility than visual evaluation and should be preferred in estimates of liver steatosis in scientific studies and in clinical contexts when the amount of steatosis is important for treatment and prognosis, such as liver transplantation.

Hepatic steatosis and HIV infection

There is increasing concern that patients with chronic HIV infection may be at increased risk of nonalcoholic fatty liver disease (NAFLD), which can evolve into nonalcoholic steatohepatitis (NASH) and cirrhosis. Multiple factors have been hypothesized to be necessary for the development and progression of this condition. Potential risk factors, which tend to accumulate in the HIV-positive population, include metabolic derangements, chronic inflammation, hepatitis coinfection, and treatment with certain nucleoside reverse transcriptase inhibitors (NRTIs). HIV-associated conditions such as hyperlactatemia and lipodystrophy frequently overlap with fatty liver disease. The cornerstone of management of HIV-associated fatty liver disease is currently to treat the predominant underlying condition. There is a need for more epidemiologic data to better define the role of comorbidities and drugs in the development of NAFLD. Further work is also needed to elucidate the pathogenesis and to evaluate the therapeutic effect of treating comorbidities and avoiding certain antiretroviral drugs.

Design and validation of a histological scoring system for nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is characterized by hepatic steatosis in the absence of a history of significant alcohol use or other known liver disease. Nonalcoholic steatohepatitis (NASH) is the progressive form of NAFLD. The Pathology Committee of the NASH Clinical Research Network designed and validated a histological feature scoring system that addresses the full spectrum of lesions of NAFLD and proposed a NAFLD activity score (NAS) for use in clinical trials. The scoring system comprised 14 histological features, 4 of which were evaluated semi-quantitatively: steatosis (0-3), lobular inflammation (0-2), hepatocellular ballooning (0-2), and fibrosis (0-4). Another nine features were recorded as present or absent. An anonymized study set of 50 cases (32 from adult hepatology services, 18 from pediatric hepatology services) was assembled, coded, and circulated. For the validation study, agreement on scoring and a diagnostic categorization ("NASH," "borderline," or "not NASH") were evaluated by using weighted kappa statistics. Inter-rater agreement on adult cases was: 0.84 for fibrosis, 0.79 for steatosis, 0.56 for injury, and 0.45 for lobular inflammation. Agreement on diagnostic category was 0.61. Using multiple logistic regression, five features were independently associated with the diagnosis of NASH in adult biopsies: steatosis (P = .009), hepatocellular ballooning (P = .0001), lobular inflammation (P = .0001), fibrosis (P = .0001), and the absence of lipogranulomas (P = .001). The proposed NAS is the unweighted sum of steatosis, lobular inflammation, and hepatocellular ballooning scores. In conclusion, we present a strong scoring system and NAS for NAFLD and NASH with reasonable inter-rater reproducibility that should be useful for studies of both adults and children with any degree of NAFLD. NAS of > or =5 correlated with a diagnosis of NASH, and biopsies with scores of less than 3 were diagnosed as "not NASH."

Tratamiento médico de la hepatopatía grasa no alcohólica primaria

The need for an effective and safe medical treatment of nonalcoholic fatty liver disease is urgent due to its high prevalence and progressive character. At the moment, therapeutic strategies are largely empirical and based on the control of associated clinical conditions (especially obesity, type 2 diabetes mellitus, and hypertriglyceridemia) and the use of some specific drugs (insulin sensitizing agents, cytoprotectives, antioxidants, and anticytokines) as an attempt to counteract known elements of the pathogenesis. None of these specifics measures have been found to display enough evidence to recommend their clinical use. It is indispensable to join efforts in coordinated networks to define, as soon as possible, the best treatment and the best time to start it.

Fructose-induced fatty liver disease: hepatic effects of blood pressure and plasma triglyceride reduction

The most known risk factor for nonalcoholic fatty liver disease (NAFLD) is the metabolic syndrome. In this study, we characterized changes in liver pathology, hepatic lipid composition, and hepatic iron concentration (HIC) occurring in rats given fructose-enriched diet (FED), with and without therapeutic maneuvers to reduce blood pressure and plasma triglycerides. Rats were given FED or standard rat chow for 5 weeks. Rats on FED were divided into 4 groups: receiving amlodipine (15 mg/kg per day), captopril (90 mg/kg per day), bezafibrate (10 mg/kg per day) in the last 2 weeks, or a control group that received FED only. FED rats had hepatic macrovesicular and microvesicular fat deposits develop, with increase in hepatic triglycerides (+198%) and hepatic cholesterol (+89%), but a decrease in hepatic phospholipids (-36%), hypertriglyceridemia (+223%), and hypertension (+15%), without increase in HIC. Amlodipine reduced blood pressure (-18%), plasma triglycerides (-12%), but there was no change in hepatic triglycerides and phospholipids concentrations. Captopril reduced blood pressure (-24%), plasma triglycerides (-36%), hepatic triglycerides (-51%), and hepatic macrovesicular fat (-51%), but increased HIC (+23%), with a borderline increase in hepatic fibrosis. Bezafibrate reduced plasma triglycerides (-49%), hepatic triglycerides (-78%), hepatic macrovesicular fat (-90%), and blood pressure (-11%). We conclude that FED rats can be a suitable model for human NAFLD. Drugs administered to treat various aspects of the metabolic syndrome could have hepatic effects. An increase in HIC in rats with NAFLD could be associated with increased hepatic fibrosis.

Abnormal aminotransferase activity in women with polycystic ovary syndrome

Alanine aminotransferase (ALT) activity was abnormal in 30% of 70 female infertility patients with polycystic ovary syndrome in whom causes other than nonalcoholic fatty liver disease were excluded by history and serum testing. Women with elevated ALT had significantly higher body mass index, waist circumference, serum triglycerides, total cholesterol-to-HDL-cholesterol ratio, and degree of insulin resistance.

A phase 2 clinical trial of metformin as a treatment for non-diabetic paediatric non-alcoholic steatohepatitis

BACKGROUND

Children with non-alcoholic steatohepatitis are insulin-resistant and metformin has been proposed as a potential therapy. However, paediatric safety and efficacy data are absent.

AIM

To test the hypothesis that metformin therapy will safely improve markers of liver disease in paediatric non-alcoholic steatohepatitis.

METHODS

Single-arm open-label pilot study of metformin 500 mg twice daily for 24 weeks in non-diabetic children with biopsy-proven non-alcoholic steatohepatitis.

RESULTS

Ten obese children (mean body mass index 30.4) enrolled and completed the trial. Mean alanine aminotransferase and aspartate aminotransferase (AST) improved significantly (P < 0.01) from baseline (184, 114 U/L) to end of treatment (98, 68 U/L). Alanine aminotransferase normalized in 40% and AST normalized in 50% of subjects. Children demonstrated significant improvements in liver fat measured by magnetic resonance spectroscopy (30-23%, P < 0.01); insulin sensitivity measured by quantitative insulin sensitivity check index (0.294-0.310, P < 0.05); and quality of life measured by pediatric quality of life inventory 4.0 (69-81, P < 0.01).

CONCLUSION

Open-label treatment with metformin for 24 weeks was notable for improvement in liver chemistry, liver fat, insulin sensitivity and quality of life. A large randomized-controlled trial is needed to definitively determine the efficacy of metformin for paediatric non-alcoholic steatohepatitis.

Histological progression of non-alcoholic fatty liver disease in Chinese patients

BACKGROUND

Non-alcoholic fatty liver disease is an important cause of chronic hepatitis and cryptogenic cirrhosis. The natural history of non-alcoholic fatty liver disease is not well understood especially in Asian populations.

AIM

To investigate the histological progression in Chinese patients with biopsy-proven non-alcoholic fatty liver disease.

METHODS

Chinese patients who had liver biopsy at least 3 years ago and confirmed to have non-alcoholic fatty liver disease were invited for a second liver biopsy. Clinical and laboratory parameters related to their liver function and metabolic syndrome were recorded and analysed. Liver biopsies were scored for the degree of steatosis, necroinflammation and fibrosis. Correlation coefficients were calculated to assess the association between changes in histological scores and metabolic parameters.

RESULTS

Seventeen patients who had been followed up for a median period of 6.1 (range: 3.8-8.0) years underwent a second liver biopsy. Nine (53%) patients had progressive disease with worsening of fibrosis score. No statistically significant correlation was found between the changes in histological scores and metabolic parameters. Seven patients developed hypertension or diabetes mellitus during the period of follow-up.

CONCLUSIONS

Non-alcoholic fatty liver disease is a progressive disease in Chinese patients as in their Caucasian counterparts. Diagnosis of non-alcoholic fatty liver disease may predate development of new components of metabolic syndrome.

Serum folate and homocysteine levels in obese females with non-alcoholic fatty liver

OBJECTIVE

Folate depletion and hyperhomocysteinemia increase the risk for hepatic alcoholic damage and promote oxidative stress in animals. In addition, some investigators have reported an inverse association between serum folate and body mass index and a positive correlation between total homocysteine and fat mass. We investigated whether there is an association between serum folate and total homocysteine concentrations with the presence of non-alcoholic fatty liver disease (NAFLD) in obese subjects.

METHODS

Forty-three obese (body mass index > or =35 kg/m2) patients who underwent bariatric surgery and hepatic biopsy were included. Serum total homocyteine, folate and vitamin B12 concentrations and hepatic enzymes were measured. Liver biopsies were graded for the presence of fat, inflammation, and fibrosis on a scale from 0 to 3. A total histologic score was calculated based on the sum of partial scores. Severe NAFLD was defined as a total score of at least 4 or severe steatosis (partial score for fat = 3).

RESULTS

Severe NAFLD was present in 17 patients. Serum folate concentration was significantly lower in obese patients with NAFLD than in those with normal liver or minimal alterations (9.3 +/- 3.5 versus 12.2 +/- 3.1 ng/mL, P = 0.005). Serum total homocysteine and vitamin B12 concentrations were similar in both groups. An inverse correlation between serum folate concentration and body mass index was observed (r = -0.31, P = 0.046).

CONCLUSIONS

In this study, severe NAFLD in obese subjects was associated with lower serum folate concentrations and serum homocysteine and vitamin B12 concentrations were not associated with liver damage in obese subjects.

Magnetic resonance spectroscopy to measure hepatic triglyceride content: prevalence of hepatic steatosis in the general population

Despite the increasing prevalence of nonalcoholic fatty liver disease (NAFLD), the criteria used to diagnose the disorder remain poorly defined. Localized proton magnetic resonance spectroscopy (MRS) accurately measures hepatic triglyceride content (HTGC) but has been used only in small research studies. Here, MRS was used to analyze the distribution of HTGC in 2,349 participants from the Dallas Heart Study (DHS). The reproducibility of the procedure was validated by showing that duplicate HTGC measurements were high correlated (r = 0.99, P < 0.001) and that the coefficient of variation between measurements was low (8.5%). Intake of a high-fat meal did not significantly affect the measurements, and values were similar when measurements were made from the right and left hepatic lobes. To determine the "upper limit of normal" for HTGC, the distribution of HTGC was examined in the 345 subjects from the DHS who had no identifiable risk factors for hepatic steatosis (nonobese, nondiabetic subjects with minimal alcohol consumption, normal liver function tests, and no known liver disease). The 95th percentile of HTGC in these subjects was 5.56%, which corresponds to a hepatic triglyceride level of 55.6 mg/g. With this value as a cutoff, the prevalence of hepatic steatosis in Dallas County was estimated to be 33.6%. Thus MRS provides a sensitive, quantitative, noninvasive method to measure HTGC and, when applied to a large urban US population, revealed a strikingly high prevalence of hepatic steatosis.

Nonalcoholic fatty liver disease: a clinical review

Nonalcoholic fatty liver disease may be the most common liver disease in the United States, with a high prevalence in the obese, type 2 diabetic population, and it is probably underestimated as a cause for cirrhosis. Clinicopathologically, it represents a wide spectrum of histologic abnormalities and clinical outcomes, ranging from benign hepatic steatosis to cirrhosis. Pathophysiologically, insulin resistance is thought to be pivotal in the development of steatosis, after which a second oxidative stressor produces lipid peroxidation and nonalcoholic steatohepatitis (NASH). Liver biopsy is the gold standard for diagnosis and prognosis. The need for an effective treatment is both clear and urgent, yet in the absence of proven therapies, treatment is directed toward weight loss and comorbidity management. For patients with NAFLD at risk of disease progression, there is a lack of large, randomized, placebo-controlled trials of adequate treatment duration, with baseline stratification according to histologic severity.

A pilot study of vitamin E versus vitamin E and pioglitazone for the treatment of nonalcoholic steatohepatitis

BACKGROUND & AIMS

Insulin resistance and oxidative stress contribute to the pathogenesis of nonalcoholic steatohepatitis (NASH). We conducted a pilot study for the following reasons: (1) to test the hypothesis that a combination of an antioxidant (vitamin E) and an insulin sensitizer (pioglitazone) would be superior to vitamin E alone for the treatment of NASH, and (2) to define the effects of these interventions on insulin-sensitive metabolic functions and correlate the effects with changes in liver histology.

METHODS

A randomized prospective trial was performed to compare the efficacy and safety of vitamin E alone (400 IU/day) vs. vitamin E (400 IU/day) and pioglitazone (30 mg/day) in nondiabetic, noncirrhotic subjects with NASH. Metabolic functions were assessed by a 2-step, hyperinsulinemic (10 and 40 mU/m2/min) euglycemic clamp.

RESULTS

A total of 10 patients were randomized to each arm. Two patients on combination therapy discontinued treatment; one because of pregnancy and the other because of hepatotoxicity. Treatment with vitamin E only produced a significant decrease in steatosis (mean grade, 2.2 vs. 1.4; P < .02). Compared with baseline, combination therapy produced a significant decrease in steatosis (mean, 2.3 vs. 1; P < .002), cytologic ballooning (1.3 vs. 0.2; P < .01), Mallory's hyaline (0.7 vs. 0.2; P < .04), and pericellular fibrosis (1.2 vs. 0.6; P < .03). Although vitamin E had no significant effects, combination therapy produced a significant increase in metabolic clearance of glucose and a decrease in fasting free fatty acid (FFA) and insulin. The decrease in fasting FFA and insulin independently predicted improvement in hepatic steatosis and cytologic ballooning.

CONCLUSIONS

A combination of vitamin E and pioglitazone produces a greater improvement in NASH histology. The improvement in steatosis and cytologic ballooning are related to treatment-associated decreases in fasting FFA and insulin levels.

Non-alcoholic fatty liver disease/non-alcoholic steatohepatitis (NAFLD/NASH): diagnosis and clinical course

Non-alcoholic fatty liver disease (NAFLD) is a frequent syndrome encompassing fatty liver alone and steatohepatitis (NASH). Often asymptomatic, the suspicion arises because of abnormal aminotransferases or a bright liver on abdominal ultrasound. It should be suspected during evaluation of associated conditions as obesity, diabetes or dyslipidaemia. The diagnostic evaluation must exclude other potential causes of liver disease and may include a liver biopsy, the only method able to confirm features of necroinflammation and fibrosis that define NASH and its prognostic implications. Indeed, the presence of necroinflammation has been associated with a significant risk of progression to cirrhosis and eventually hepatocellular carcinoma. Age >45 years, obesity and diabetes have also been associated with an increased risk of liver fibrosis and progression to cirrhosis. Given the high prevalence of NAFLD, general measures of life-style changes, focusing on exercise, diet, and total alcohol abstinence, should be implemented before a liver biopsy is considered.

Prevalence of hepatic steatosis in an urban population in the United States: impact of ethnicity

Despite the increasing prevalence of nonalcoholic fatty liver disease (NAFLD), its pathogenesis and clinical significance remain poorly defined. In this study, we examined and compared the distribution of hepatic triglyceride content (HTGC) in 2,287 subjects from a multiethnic, population-based sample (32.1% white, 48.3% black, and 17.5% Hispanic) using proton magnetic resonance spectroscopy. HTGC varied over a wide range (0.0%-41.7%; median, 3.6%) in the population. Almost one third of the population had hepatic steatosis, and most subjects with hepatic steatosis had normal levels of serum alanine aminotransferase (79%). The frequency of hepatic steatosis varied significantly with ethnicity (45% in Hispanics; 33% in whites; 24% in blacks) and sex (42% in white men; 24% in white women). The higher prevalence of hepatic steatosis in Hispanics was due to the higher prevalence of obesity and insulin resistance in this ethnic group. However, the lower frequency of hepatic steatosis in blacks was not explained by ethnic differences in body mass index, insulin resistance, ethanol ingestion, or medication use. The prevalence of hepatic steatosis was greater in men than women among whites, but not in blacks or Hispanics. The ethnic differences in the frequency of hepatic steatosis in this study mirror those observed previously for NAFLD-related cirrhosis (Hispanics > whites > blacks). In conclusion, the significant ethnic and sex differences in the prevalence of hepatic steatosis documented in this study may have a profound impact on susceptibility to steatosis-related liver disease.

Oxidative Stress in Nonalcoholic Fatty Liver Disease: Pathogenesis and Antioxidant Therapies

Nonalcoholic fatty liver disease is a common cause of chronic liver disease, a common finding on liver biopsy in those patients with abnormal blood transaminase levels, and a common cause of cryptogenic cirrhosis in the United States. The prevalence of this disorder is expected to rise with the increase in obesity, and the clinical spectrum can range from simple steatosis (fatty liver) to cirrhosis of the liver. Insulin resistance is thought to be pivotal for the development of steatosis, and oxidative stress may be a potential factor that can promote hepatic necroinflammation and fibrosis. Preliminary studies have examined the role of oxidative stress and antioxidants in animal and human studies of this disorder. Efforts to improve the hepatic antioxidant system could be achieved by optimizing the patient's diet, by supplementation with precursors for antioxidants, or by supplementation with essential metals and/or antioxidants. Randomized, controlled trials are required to examine these potential approaches using patients with this disorder.

Prevalence and determinants of diabetes mellitus among Iranian patients with chronic liver disease

BACKGROUND: Alterations in carbohydrate metabolism are frequently observed in cirrhosis. We conducted this study to define the prevalence of diabetes mellitus (DM) and impaired glucose tolerance (IGT) in Iranian patients with chronic liver disease (CLD), and explore the factors associated with DM in these patients. METHODS: One hundred and eighty-five patients with CLD were enrolled into the study. Fasting plasma glucose and two-hour plasma glucose were measured in patients' sera. DM and IGT were diagnosed according to the latest American Diabetes Association criteria. RESULTS: The subjects included 42 inactive HBV carriers with a mean age of 42.2 +/- 12.0 years, 102 patients with HBV or HCV chronic hepatitis with a mean age of 41.2 +/- 10.9 years, and 41 cirrhotic patients with a mean age of 52.1 +/- 11.4 years. DM and IGT were diagnosed in 40 (21.6%) and 21 (11.4%) patients, respectively. Univariate analysis showed that age (P = 0.000), CLD status (P = 0.000), history of hypertension (P = 0.007), family history of DM (P = 0.000), and body mass index (BMI) (P = 0.009) were associated with DM. Using Multivariate analysis, age (OR = 4.7, 95%CI: 1.8-12.2), family history of DM (OR = 6.6, 95%CI: 2.6-17.6), chronic hepatitis (OR = 11.6, 95%CI: 2.9-45.4), and cirrhosis (OR = 6.5, 95%CI: 2.4-17.4) remained as the factors independently associated with DM. When patients with cirrhosis and chronic hepatitis were analyzed separately, higher Child-Pugh's score in cirrhotic patients (OR = 9.6, 95%CI: 1.0-88.4) and older age (OR = 7.2, 95%CI: 1.0-49.1), higher fibrosis score (OR = 59.5, 95%CI: 2.9-1211.3/ OR = 11.9, 95%CI: 1.0-132.2), and higher BMI (OR = 30.3, 95%CI: 3.0-306.7) in patients with chronic hepatitis were found to be associated with higher prevalence of DM. CONCLUSIONS: Our findings indicate that patients with cirrhosis and chronic hepatitis are at the increased risk of DM occurrence. Older age, severe liver disease, and obesity were associated with DM in these patients.

Hepatitis C and steatosis

Steatosis is a common finding in patients with chronic hepatitis C (CHC) due to a combination of the direct steatogenic effect of hepatitis C virus (HCV) and the prevalence of metabolic risk factors in the HCV population. Steatosis is now established as a risk factor for disease progression in CHC and significantly impacts therapeutic response. Research efforts should continue to focus on defining the complex viral and host interactions involved in the pathogenesis of HCV-related steatosis so that future therapeutic strategies may be accurately and appropriately targeted.

Evaluation and management of non-alcoholic steatohepatitis

Non-alcoholic fatty liver disease represents a spectrum of liver diseases which occurs in the absence of alcohol consumption in amounts considered injurious to the liver. Non-alcoholic fatty liver disease includes both non-alcoholic fatty liver and non-alcoholic steatohepatitis. We present an integrated approach that utilizes both clinical and laboratory studies to diagnose and manage a patient with suspected non-alcoholic steatohepatitis. The goals of treatment include (1) correction of the underlying risk factors, (2) avoidance of factors that promote progression of liver disease, and (3) specific treatment of non-alcoholic steatohepatitis.

Nonalcoholic steatohepatitis: histologic features and clinical correlations with 30 blinded biopsy specimens

Thirty overweight patients with clinically characterized and biopsy proven nonalcoholic steatohepatitis (NASH) were enrolled in a 48-week treatment trial with rosiglitazone, a peroxisome proliferator-activator receptor (PPAR)-gamma agonist that enhances insulin sensitivity. Improvement in laboratory liver tests, insulin resistance and liver fat content were documented; blinded biopsy review demonstrated decreases in necroinflammatory activity or grade and in individual components of grade, and changes in the relationship of lobular and portal inflammation as well as in the nature of perisinusoidal fibrosis. The current study identified correlations of histological features of the protocol entry biopsy specimens with contemporaneous laboratory and imaging tests. Significant correlations with histologically assessed steatosis were liver fat, evaluated by computed tomography (P = 0.001); mean HbA1C, a measure of glycemic control (P = 0.004); and QUICKI, a measure of insulin sensitivity (P = 0.05). Histologically determined grades of steatohepatitis (SH) correlated with HbA1C (P = 0.01), and a trend toward elevated fasting glucose levels was seen. No subject in the study was cirrhotic at entry; fibrosis scores of the 30 subjects did not significantly correlate with age, gender, body mass index, or clinical tests. All subjects underwent 3 biopsies (prior, entry, and posttreatment), and all had undergone a prior biopsy with diagnostic SH. By blinded analysis, 7 study entry biopsy specimens did not fulfill published strict criteria for SH. Laboratory results from these subjects included normal fasting glucose level and, compared with the 23 subjects with criteria for SH, lower mean alanine aminotransferase and aspartate aminotransferase levels (P = 0.02 for both), less insulin resistance (P = 0.03), and lower mean HbA1C (P = 0.001). We conclude that biopsy findings determined by blinded analysis correlated with image-detected steatosis, laboratory markers of hepatic inflammation, insulin resistance, and long-term glycemia; the findings confirm the usefulness of strict histological criteria in the evaluation of NASH.

Natural history of nonalcoholic steatohepatitis: a longitudinal study of repeat liver biopsies

Nonalcoholic steatohepatitis may cause severe fibrosis, cirrhosis, and hepatocellular carcinoma, but supporting evidence is based on indirect data. Few publications have examined the results of repeat liver biopsies to evaluate progression of fibrosis. The aims of this study were to assess rate of fibrosis progression in untreated patients with nonalcoholic steatohepatitis and to identify associated variables. Among 106 patients, a second liver biopsy was proposed to those who had undergone their first liver biopsy at least 3 years before. None of them had been given pharmacological therapy. Liver biopsy samples were evaluated blindly. Variables were compared between patients with (group P) and without (group NP) fibrosis progression, using a Wilcoxon rank-sum test for numerical variables and a difference of two binomial proportions for categorical ones. Twenty-two patients (median age, 45 years; age range, 20-69 years; 13 women; diabetes in 8 patients, obesity in 10 patients) underwent a second liver biopsy 4.3 years (range, 3.0-14.3 years) after the first. Fibrosis progression was found in 7 patients in group P (31.8%), no progression was found in 15 patients in group NP. There were no differences between both groups regarding age, gender, diabetes, hyperlipidemia, ALT levels, AST-to-ALT ratio levels, albumin levels, prothrombin activity, steatosis, or inflammation. Obesity was significantly more prevalent in group P (86%) than in group NP (27%; P =.01). Basal body mass index was higher in group P (median, 33.2; range, 29.1-38.2) than in group NP (median, 29.0; range, 24.0-38.1; P =.024). Time between biopsies was not different between groups. In conclusion, progression of liver fibrosis was found in a third of nonalcoholic steatohepatitis patients 4.3 years after the first liver biopsy, and obesity and body mass index were the only associated factors with such progression.

Interleukin 6 alleviates hepatic steatosis and ischemia/reperfusion injury in mice with fatty liver disease

Fatty liver, formerly associated predominantly with excessive alcohol intake, is now also recognized as a complication of obesity and an important precursor state to more severe forms of liver pathology including ischemia/reperfusion injury. No standard protocol for treating fatty liver exists at this time. We therefore examined the effects of 10 days of interleukin 6 (IL-6) injection in 3 murine models of fatty liver: leptin deficient ob/ob mice, ethanol-fed mice, and mice fed a high-fat diet. In all 3 models, IL-6 injection decreased steatosis and normalized serum aminotransferase. The beneficial effects of IL-6 treatment in vivo resulted in part from an increase in mitochondrial beta oxidation of fatty acid and an increase in hepatic export of triglyceride and cholesterol. However, administration of IL-6 to isolated cultured steatotic hepatocytes failed to decrease lipid contents, suggesting that the beneficial effects of IL-6 in vivo do not result from its effects on hepatocytes alone. IL-6 treatment increased hepatic peroxisome proliferator-activated receptor (PPAR) alpha and decreased liver and serum tumor necrosis factor (TNF) alpha. Finally, 10 days of treatment with IL-6 prevented the susceptibility of fatty livers to warm ischemia/reperfusion injury. In conclusion, long-term IL-6 administration ameliorates fatty livers and protects against warm ischemia/reperfusion fatty liver injury, suggesting the therapeutic potential of IL-6 in treating human fatty liver disease.

The wide spectrum of steatohepatitis: a report of four cases and a review of the literature

We report on four cases displaying the wide range of aetiological risk factors (presence or absence of family history of dyslipidaemia and cryptogenic cirrhosis, from subnormal body mass index through morbid obesity, from absent through hepatotoxic alcohol consumption), laboratory test results (from subnormal through elevated uric acid and ferritin values), ultrasonographic changes (from normal findings through 'bright liver' with or without attenuation of ultrasound beam and absence/presence of focal lesions), and histological severity of steatohepatitis (fibrosis appearing to be inversely related to the amount of liver fat but zone 3 accentuation of lesions and ballooning being observed in all cases). Cases illustrate the concepts of overlapping aetiologies of steatohepatitis (hepatitis C, diabetes and lipodystrophy); the relationships between cryptogenic cirrhosis, familial cirrhosis, non-alcoholic fatty liver disease and hepatocellular carcinoma; familial hypobetalipoproteinaemia as an aetiology of steatohepatitis; and alcoholic liver disease in the obese. These issues, which are worthy of future investigation, are reviewed.

Beneficial effects of tumor necrosis factor-alpha inhibition by pentoxifylline on clinical, biochemical, and metabolic parameters of patients with nonalcoholic steatohepatitis

BACKGROUND

Tumor necrosis factor-alpha (TNF-alpha) has been incriminated to play an important role in the pathogenesis of nonalcoholic steatohepatitis (NASH). Pentoxifylline, a TNF-alpha inhibitor could prove useful in treating patients with NASH.

METHODS

Eighteen patients (mean age, 34 +/- 7.8 yr) with histologically proven NASH and with persistently elevated ALT (>1.5 times) were given pentoxifylline at a dosage of 400 mg t.i.d. for 6 months. No lipid-lowering agent or antioxidants were concurrently advised.

RESULTS

Impaired fasting glycemia, impaired glucose tolerance, diabetes mellitus, and hypertriglyceridemia were noted in 6, 35, 17, and 53% of the patients, respectively. After 6 months of therapy, fatigue improved (55.6 vs 20%, p= 0.016), but serum triglyceride (182 +/- 66 vs 160 +/- 55 mg/dl, p= 0.397), cholesterol (173 +/- 46 vs 162 +/- 40 mg/dl, p= 0.440), and body mass index (BMI) (27.3 +/- 3.1 vs 26 +/- 3.1 kg/m(2), p= 0.087) remained unchanged. Mean AST (66 +/- 29 vs 33 +/- 11 IU/l, p < 0.0001) and ALT (109 +/- 44 vs 47 +/- 20 IU/l, p < 0.0001) reduced significantly. ALT normalized in 23% at month 1 (p= 0.125), 35% at month 2 (p= 0.125), and 60% at month 6 (p= 0.008) of treatment. The insulin resistance index assessed by homeostatic metabolic assessment (HOMA(IR)) improved (5.1 +/- 3.4 vs 2.6 +/- 2, p = 0.046) and the serum TNF-alpha reduced significantly after therapy (22.15 +/- 2.49 vs 17 +/- 2.58 pg/ml, p = 0.011). The drug was well tolerated.

CONCLUSIONS

In patients with NASH, pentoxifylline therapy effectively achieved significant clinical and biochemical improvement with reduction in HOMA(IR). These benefits are possibly mediated through suppression of TNF-alpha.

High prevalence of metabolic complications in patients with non-alcoholic fatty liver disease

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is considered to be the liver component of the metabolic syndrome and is frequently associated with obesity, dyslipidemia and type II diabetes mellitus (NIDDM). We aimed to determine the development of liver function tests (LFTs) and metabolic complications in patients previously diagnosed with NAFLD.

METHODS

One-hundred-and-two patients with NAFLD diagnosed in the period 1994-2001 were identified. Eighty were brought in for new investigations, including LFTs, blood pressure, BMI, lipid profile, blood glucose and insulin. Original liver biopsy was re-evaluated.

RESULTS

Sixty-two patients (77%) were males (median age 46 years; mean follow-up time 2.8 +/- 1.2 years). Fifty-four patients (68%) were light to moderately overweight with body mass index (BMI) 25-30 kg/m. Mean BMI (28.2) was the same at diagnosis and at follow-up (28.3). At the new examination, 18 patients (23%) had developed diabetes mellitus type II (n = 6) or had impaired fasting glucose (IFG) (n = 12), compared to only 2 patients at diagnosis. Hyperinsulinemia was observed in 19 patients (24%). Dyslipidemia, with elevated triglycerides and/or hypercholesterolemia, was now present in 65 patients (81%). Twenty-two patients (27%) had hypertension compared to 9 (11%) at diagnosis. Liver biopsy was performed in 24%, and 89% of those fulfilled the criteria for NASH. However, mild inflammation and fibrosis was observed, grade 1-2 (n = 17), stage I-II (n = 13) and none had cirrhosis.

CONCLUSION

A significant proportion of patients with both clinical and histological diagnosis of NAFLD develop metabolic problems soon after diagnosis. These patients should be screened regularly for metabolic disorders.

Insulin resistance and the pathogenesis of nonalcoholic fatty liver disease

The prevalence of obesity has reached epidemic proportions in most of the western world. Current estimates suggest that 22.5%of the population of the United States suffers from obesity and is at risk for development of obesity-related complications, including hypertension, coronary artery disease, diabetes, hyperlipidemia,increased predisposition for various cancers, and nonalcoholic fatty liver disease. Fatty liver disease is currently the most common abnormality observed in hepatology practice. Since it was first reported in the 1980s in obese diabetic females, our understanding of nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH) has undergone significant metamorphosis. It is now universally accepted that insulin resistance and subsequent hyperinsulinemia are key factors that lead to both NAFL and NASH.This article reviews the role of insulin resistance in the genesis of these conditions.

The clinical features, diagnosis and natural history of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) has emerged as the most common chronic liver disease in the United States. The histologic spectrum of NAFLD ranges from steatosis liver alone to nonalcoholic steatohepatitis (NASH), which is the most serious form of NAFLD. NASH is a progressive fibrotic disease, in which cirrhosis and liver-related death occur in up to 20% and 12%, respectively, over a 10-year period. NASH-associated cirrhosis also can develop into subacute liver failure, progress to hepatocellular carcinoma, and reoccur post-transplantation. In contrast, steatosis alone has a more benign clinical course, although progression to cirrhosis has occurred in 3% of these patients. The major risk factors for fibrosis include diabetes or obesity, an aspartate aminotransferase/alanine aminotransferase ratio of greater than 1, age older than 50, and hepatic histology.

Portal fibrosis and hepatic steatosis in morbidly obese subjects: A spectrum of nonalcoholic fatty liver disease

Nonalcoholic steatohepatitis (NASH) is a progressive form of nonalcoholic fatty liver disease (NAFLD) that can lead to hepatic fibrosis and cirrhosis. Portal fibrosis in the absence of NASH, called isolated portal fibrosis (IPF), has received less attention and has not been classified as a spectrum of NAFLD. The aims of this study were to determine the prevalence of IPF in subjects undergoing gastric bypass surgery, to identify biochemical variables associated with IPF, and to assess the metabolic syndrome as defined by the AdultTreatment Panel III criteria. We analyzed liver biopsies from 195 morbidly obese subjects after excluding all other causes of liver disease. The prevalence of fatty liver (FL) only, IPF, and NASH was 30.3%, 33.3%, and 36.4%, respectively. Several biochemical parameters significantly trended across the 3 groups, with IPF falling between FL and NASH. Hyperglycemia was the only metabolic parameter associated with NASH (OR, 5.4; 95% CI, 2.4-12; P < .0001) and IPF (OR, 2.8; 95% CI, 1.2-6.5; P = .01). Subjects with diabetes had the greatest risk for NASH (OR, 8; 95% CI, 3.3-19.7; P < .0001) and IPF (OR, 4.3; 95% CI, 1.6-11.6; P = .003). The metabolic syndrome was identified in 78.5% of subjects, and a significant trend for the number of metabolic criteria was observed across the spectrum of FL, IPF, and NASH. In conclusion, a significant subset of morbidly obese individuals has portal fibrosis in the absence of NASH that is associated with glycemic dysregulation. Therefore, IPF should be considered a spectrum of NAFLD that may prelude NASH in morbid obesity.

Reduced expression of peroxisome proliferator-activated receptor-alpha may have an important role in the development of non-alcoholic fatty liver disease

BACKGROUND

Although the pathogenesis of non-alcoholic fatty liver disease (NAFLD) remains poorly understood, metabolic syndrome associated with insulin resistance is the most reproducible factor in the development of NAFLD. Fat accumulation in hepatocytes results from an imbalance in the input, output and oxidation of fatty acid. Peroxisomes contain a battery of fatty acid oxidizing enzymes, the first of which, acyl-CoA oxidase (AOX), initiates the beta-oxidation spiral. One of the mammalian peroxisome proliferator-activated receptors (PPAR), PPAR-alpha, regulates the transcriptional expression of the enzymes involved in fatty acid beta-oxidation. The aim of the present study was to define the role of PPAR-alpha and AOX in the development of NAFLD using the Otsuka Long-Evans Tokushima fatty (OLETF) rat model.

METHODS

Liver tissue from OLETF (n = 12) and control (n = 10) rats 12, 28, and 40 weeks old were processed for histopathological and western blot analysis. The messenger RNA of PPAR-alpha and AOX were quantified by real-time RT-PCR.

RESULTS

At 40 weeks old, the histological analysis of the OLETF rat liver had steatosis (approximately 66%) and mild inflammation, which were comparable to those in NAFLD. Histological changes were unremarkable in 12 week and 28 week rats. In 12 week OLETF rats, the mRNA of AOX was 63% of the control. Expression of PPAR-alpha mRNA was also reduced to 3% that of the control. Along with the changes of mRNA, the protein expression of PPAR-alpha was also significantly reduced to 17% that of the control. In 28 week and 40 week animals, PPAR-alpha protein expression gradually increased to 75% and 78% that of the control. Expression of PPAR-alpha mRNA was also increased by up to 26% and 110% of the control. AOX, regulated by PPAR-alpha, also increased to 149% and 120% of the control.

CONCLUSION

Reduced expression of PPAR-alpha and AOX was observed even before definite steatosis had developed. The alteration of peroxisomal fatty acid metabolism may have an important role in the development of NAFLD.

Mechanism of Hepatic Insulin Resistance in Non-alcoholic Fatty Liver Disease

Short term high fat feeding in rats results specifically in hepatic fat accumulation and provides a model of non-alcoholic fatty liver disease in which to study the mechanism of hepatic insulin resistance. Short term fat feeding (FF) caused a approximately 3-fold increase in liver triglyceride and total fatty acyl-CoA content without any significant increase in visceral or skeletal muscle fat content. Suppression of endogenous glucose production (EGP) by insulin was diminished in the FF group, despite normal basal EGP and insulin-stimulated peripheral glucose disposal. Hepatic insulin resistance could be attributed to impaired insulin-stimulated IRS-1 and IRS-2 tyrosine phosphorylation. These changes were associated with activation of PKC-epsilon and JNK1. Ultimately, hepatic fat accumulation decreased insulin activation of glycogen synthase and increased gluconeogenesis. Treatment of the FF group with low dose 2,4-dinitrophenol to increase energy expenditure abrogated the development of fatty liver, hepatic insulin resistance, activation of PKC-epsilon and JNK1, and defects in insulin signaling. In conclusion, these data support the hypothesis hepatic steatosis leads to hepatic insulin resistance by stimulating gluconeogenesis and activating PKC-epsilon and JNK1, which may interfere with tyrosine phosphorylation of IRS-1 and IRS-2 and impair the ability of insulin to activate glycogen synthase.