Association between alcohol intake amount and prevalence of metabolic syndrome in Korean rural male population

Moderate alcohol consumption is known to be associated with a reduced risk of cardiovascular disease and mortality. However, few studies reported that long-term alcohol drinking may increase the prevalence of central obesity, and cardiovascular disease. We examined the association between metabolic syndrome, nutritional factors and alcohol intake amount in Korean male rural population. We performed a cross-sectional analysis on data from Korean Rural Genomic Cohort (KRGC) study. We used multiple logistic regression analysis to estimate the adjusted odds ratio of metabolic syndrome according to alcohol intake amount categories (never, 0-16 g/day, 16-40 g/day, and >40 g/day). The age adjusted odds ratio for the prevalence of metabolic syndrome was significantly increased in the quartile with the highest alcohol consumption compared to the non-alcohol drinking group (1.33; C.I., 1.11-1.59). These results were similar in the high energy intake group, but not in the low energy intake group. Waist circumference, blood pressure, and serum triglyceride levels were significantly higher in the quartile with the highest alcohol consumption compared to the non-alcohol drinking group. These results suggest that large alcohol consumption is associated with metabolic syndrome and may be a modifiable risk factor of metabolic syndrome especially in subjects with high calorie intake.

Nonobese population in a developing country has a high prevalence of nonalcoholic fatty liver and significant liver disease

There is a paucity of community-based epidemiological data on nonalcoholic fatty liver (NAFL) among nonaffluent populations in developing countries. Available studies are radiological and/or biochemical and lack histological assessment, limiting their strength. We conducted a prospective epidemiological study comprising a 1:3 subsample of all adult (>18 years) inhabitants of a rural administrative unit of West Bengal, India. Subjects positive for hepatitis B virus and/or hepatitis C virus infection and consuming any amount of alcohol were excluded. Diagnosis of NAFL was by dual radiological screening protocol consisting of ultrasonographic and computed tomographic examination of the liver. Transient elastographic examination and liver biopsy were performed in a subset to identify significant liver disease. The risk factors of having NAFL were analyzed. A total of 1,911 individuals were analyzed, 7% of whom were overweight and 11% of whom had abdominal obesity. The prevalence of NAFL, NAFL with elevated alanine aminotransferase, and cryptogenic cirrhosis was 8.7%, 2.3%, and 0.2%, respectively. Seventy-five percent of NAFL subjects had a body mass index (BMI) <25 kg/m(2), and 54% were neither overweight nor had abdominal obesity. The subjects with the highest risk of having NAFL were those with a BMI >25 kg/m(2) (odds ratio 4.3, 95% confidence interval 1.6-11.5). Abdominal obesity, dysglycemia (fasting plasma glucose >100 mg/dL or elevated homeostatic model assessment of insulin resistance), and higher income were the other risk factors. Even having a normal BMI (18.5-24.9 kg/m(2)) was associated with a 2-fold increased risk of NAFL versus those with a BMI <18.5 kg/m(2).

CONCLUSION

There is a significant prevalence of NAFL and potentially significant liver disease, including cryptogenic cirrhosis, in this predominantly nonobese, nonaffluent population in a developing country. NAFL will be a major determinant of future liver disease burden in countries of the developing world.

The role of fructose in the pathogenesis of NAFLD and the metabolic syndrome

Nonalcoholic fatty liver disease (NAFLD) is the most frequent liver disease worldwide, and is commonly associated with the metabolic syndrome. Secular trends in the prevalence of these diseases may be associated with the increased fructose consumption observed in the Western diet. NAFLD is characterized by two steps of liver injury: intrahepatic lipid accumulation (hepatic steatosis), and inflammatory progression to nonalcoholic steatohepatitis (NASH) (the 'two-hit' theory). In the first 'hit', hepatic metabolism of fructose promotes de novo lipogenesis and intrahepatic lipid, inhibition of mitochondrial beta-oxidation of long-chain fatty acids, triglyceride formation and steatosis, hepatic and skeletal muscle insulin resistance, and hyperglycemia. In the second 'hit', owing to the molecular instability of its five-membered furanose ring, fructose promotes protein fructosylation and formation of reactive oxygen species (ROS), which require quenching by hepatic antioxidants. Many patients with NASH also have micronutrient deficiencies and do not have enough antioxidant capacity to prevent synthesis of ROS, resulting in necroinflammation. We postulate that excessive dietary fructose consumption may underlie the development of NAFLD and the metabolic syndrome. Furthermore, we postulate that NAFLD and alcoholic fatty liver disease share the same pathogenesis.

Nonalcoholic fatty liver disease and hepatocellular carcinoma: a weighty connection

Hepatocellular carcinoma (HCC) is a common and deadly malignancy that is increasing in incidence in developed countries. The emergence of hepatitis C virus (HCV) accounts for about half of this increase in HCC, although the etiology of HCC in 15%-50% of new HCC cases remains unclear. The most common form of chronic liver disease in developed countries is nonalcoholic fatty liver disease (NAFLD), which encompasses a broad spectrum of histopathology. The prevalence of NAFLD, including the more aggressive nonalcoholic steatohepatitis (NASH), is increasing with the growing epidemics of diabetes and obesity. NASH can progress to cirrhosis and its related complications. Growing evidence suggests that NASH accounts for a large proportion of idiopathic or cryptogenic cirrhosis, which is associated with the typical risk factors for NASH. HCC is a rare, although important complication of NAFLD. Diabetes and obesity have been established as independent risk factors for the development of HCC. New evidence also suggests that hepatic iron deposition increases the risk of HCC in NASH-derived cirrhosis. Multiple case reports and case reviews of HCC in the setting of NASH support the associations of diabetes and obesity with the risk of HCC, as well as suggest age and advanced fibrosis as significant risks. Insulin resistance and its subsequent inflammatory cascade that is associated with the development of NASH appear to play a significant role in the carcinogenesis of HCC. The complications of NASH, including cirrhosis and HCC, are expected to increase with the growing epidemic of diabetes and obesity.

Relative roles of HBsAg seroclearance and mortality in the decline of HBsAg prevalence with increasing age

OBJECTIVES

Mortality and hepatitis B surface antigen (HBsAg) seroclearance are the two extremes of prognostic destination of chronic hepatitis B virus (HBV) infection. Their relative roles in the decline of HBsAg prevalence with increasing age are unknown.

METHODS

HBsAg-seropositive subjects with near normal alanine aminotransferase (ALT) were followed up every 3 to 12 months for >1 year. Serum HBsAg was assayed at entry and re-assayed at 3- to 5-year intervals. The morbidity and mortality data were obtained from hospital records, cancer registration, and the national mortality database. The mortality and HBsAg-seroclearance rates were examined by survival analysis.

RESULTS

At entry, 1,386 subjects (20.9%) were hepatitis B e antigen (HBeAg) seropositive and 5,235 were HBeAg seronegative. The mean follow-up period was 13.6+/-5.4 years (median 13.2; range 1-29.1). HBsAg seroclearance occurred more frequently (555 cases, 8.4%) than mortality (97 cases, 1.5%; P<0.001; overall HBsAg seroclearance/mortality ratio: 5.6), of which only 40% were liver-related cases. Cox regression analysis revealed that male sex, HBeAg negativity, older age, low maximal ALT level, and hepatic steatosis were factors associated with HBsAg seroclearance. The estimated annual HBsAg seroclearance rate was around 1.05-1.61% after the age of 50 years, whereas the estimated mortality rate was quite low before the age of 60 and increased from 0.41% per year at ages 60-64 to 1.19% per year at ages 70-74 years.

CONCLUSIONS

The HBsAg seroclearance over mortality rate was 5.6 in this cohort. This suggests that HBsAg seroclearance is the main reason for decreasing HBsAg prevalence with increasing age in the population.

The role of hepatic fat accumulation in pathogenesis of non-alcoholic fatty liver disease (NAFLD)

Nonalcoholic fatty liver disease is increasingly regarded as a hepatic manifestation of metabolic syndrome, and the severity of nonalcoholic fatty liver disease seems to increase in parallel with other features of metabolic syndrome. Excess lipid accumulation in the liver cells is not only a mediator of Metabolic Syndrome and indicator of a lipid overload but also accompanied by a range of histological alterations varying from 'simple' steatosis to nonalcoholic steatohepatitis, with time progressing to manifest cirrhosis. Hepatocellular carcinoma may also occur in nonalcoholic steatohepatitis -related cirrhosis with a mortality rate similar to or worse than for cirrhosis associated with hepatitis C. This review summarizes the knowledge about the causal relationship between hepatic fat accumulation, insulin resistance, liver damage and the etiological role of hepatic fat accumulation in pathogenesis of extra- and intra-hepatic manifestations. Special emphasis is given suggestions of new targets treatment and prevention of nonalcoholic fatty liver disease.

Association between serum uric acid and non-alcoholic fatty liver disease in Korean adults

BACKGROUND

Increased uric acid is associated with the metabolic syndrome, conditions linked to oxidative stress and insulin resistance. Non-alcoholic fatty liver disease (NAFLD) is now considered a hepatic manifestation of insulin resistance. However, little has been written regarding the association between uric acid and NAFLD.

METHODS

We examined the association between uric acid and the presence of NAFLD in 3768 Koreans (2133 men, 1635 women; aged 20-75 years) in a health examination program. Uric acid quartiles were categorized separately as follows: Q1: <or=291.5, Q2: 291.6-333.1, Q3: 333.2-380.7, and Q4: >or=380.8 micromol/L for men; Q1: <or=202.2, Q2: 202.3-232.0, Q3: 231.1-267.7, and Q4: >or=267.8 micromol/L for women. Hepatic steatosis was diagnosed based on abdominal ultrasonographic findings by hyperechogenicity of liver tissue, difference of echogenicity between the liver and diaphragm, and visibility of vascular structures. The odds ratios (ORs) and 95% confidence intervals (CIs) for NAFLD were calculated across each quartile of serum uric acid.

RESULTS

The prevalence of NAFLD was 25.8% (32.2% in men and 17.4% in women). After adjustment for age, body mass index (BMI), smoking, regular exercise, blood pressure, fasting plasma glucose (FPG), triglycerides, and high-density lipoprotein (HDL) cholesterol, the ORs (95% CIs) for NAFLD according to each quartile of uric acid were 1.00, 1.55 (1.13-2.14), 1.77 (1.30-2.41), and 2.01 (1.45-2.78) for men and 1.00, 0.69 (0.40-1.20), 1.12 (0.67-1.88), and 1.94 (1.21-3.13) for women.

CONCLUSIONS

Serum uric acid is independently associated with the presence of NAFLD, and uric acid may be a useful additional measure in assessing the risk of NAFLD in the clinical setting.

Fatty liver incidence and predictive variables

Although fatty liver predicts ischemic heart disease, the incidence and predictors of fatty liver need examination. The objective of this study was to determine fatty liver incidence and predictive variables. Using abdominal ultrasonography, we followed biennially through 2007 (mean follow-up, 11.6+/-4.6 years) 1635 Nagasaki atomic bomb survivors (606 men) without fatty liver at baseline (November 1990 through October 1992). We examined potential predictive variables with the Cox proportional hazard model and longitudinal trends with the Wilcoxon rank-sum test. In all, 323 (124 men) new fatty liver cases were diagnosed. The incidence was 19.9/1000 person-years (22.3 for men, 18.6 for women) and peaked in the sixth decade of life. After controlling for age, sex, and smoking and drinking habits, obesity (relative risk (RR), 2.93; 95% confidence interval (CI), 2.33-3.69, P<0.001), low high-density lipoprotein-cholesterol (RR, 1.87; 95% CI, 1.42-2.47; P<0.001), hypertriglyceridemia (RR, 2.49; 95% CI, 1.96-3.15; P<0.001), glucose intolerance (RR, 1.51; 95% CI, 1.09-2.10; P=0.013) and hypertension (RR, 1.63; 95% CI, 1.30-2.04; P<0.001) were predictive of fatty liver. In multivariate analysis including all variables, obesity (RR, 2.55; 95% CI, 1.93-3.38; P<0.001), hypertriglyceridemia (RR, 1.92; 95% CI, 1.41-2.62; P<0.001) and hypertension (RR, 1.31; 95% CI, 1.01-1.71; P=0.046) remained predictive. In fatty liver cases, body mass index and serum triglycerides, but not systolic or diastolic blood pressure, increased significantly and steadily up to the time of the diagnosis. Obesity, hypertriglyceridemia and, to a lesser extent, hypertension might serve as predictive variables for fatty liver.

[Ultrasound in the diagnostics of fatty liver in obesity]

Chronic diffuse liver diseases produce a characteristic ultrasound image called bright liver. On the basis of liver attenuation, two major appearances can be observed: low and high attenuation types. It is proved that high attenuation is associated with fatty liver and subcutaneous fat thickness correlates with attenuation. Cut-off value of attenuation and subcutaneous fat thickness was searched for differentiation of the two attenuation types and that of the normal livers. 441 patients (proved by histology) were examined by ultrasound. 132 normal livers, 176 low and 133 high attenuation type bright livers were found. Cut-off level of attenuation, determined by frequency distribution analysis was defined as 1.1 dB/cm/MHz, between fatty liver and low attenuation type bright liver and normal liver. Cut-off value for subcutaneous fat thickness could not be determined. It is concluded, that above the cut-off point of attenuation, the diagnosis of fatty liver can be established without liver biopsy. Subcutaneous fat thickness values give additive confirmative data.

Prevention of hepatocellular carcinoma in the Asia-Pacific region: consensus statements

Among approximately 650,000 people who die from hepatocellular carcinoma (HCC) each year, at least two-thirds live in Asia. Efforts to improve early diagnosis and treatment have not yet impacted mortality. An Asia-Pacific Working Party convened in Hong Kong in June 2008 to consider ways to prevent HCC in this region. Separate reviews have summarized epidemiology of HCC, preventive approaches related to hepatitis B virus (HBV), hepatitis C virus (HCV) and non-viral liver diseases, and the role of surveillance to detect HCC at a curative stage. We now present Consensus Statements from these deliberations and reviews. As chronic hepatitis B is the most common cause of HCC in Asia, effective hepatitis B vaccination programs are the most important strategy to reduce HCC incidence. Prevention of HCV by screening blood donors, universal precautions against blood contamination in health-care settings and reducing HCV transmission from injection drug use are also vital. There is strong evidence that effective antiviral therapy to control HBV infection or eradicate HCV substantially reduces (but does not abolish) HCC risk. With hemochromatosis, family screening, early diagnosis and correcting iron overload to prevent liver fibrosis prevents HCC. There is currently insufficient evidence to give firm recommendations on alcohol, obesity/metabolic risk factors and other liver diseases. HCC surveillance for high-risk groups is recommended in individual cases but cost-effectiveness is not as high as infant hepatitis B vaccination and screening blood for HCV. Widespread application of HCC surveillance in Asia-Pacific countries depends on economic factors and health-care priorities.

A fresh look at NASH pathogenesis. Part 1: the metabolic movers

The strong relationship between over-nutrition, central obesity, insulin resistance/metabolic syndrome and non-alcoholic fatty liver disease (NAFLD) suggest pathogenic interactions, but key questions remain. NAFLD starts with over-nutrition, imbalance between energy input and output for which the roles of genetic predisposition and environmental factors (diet, physical activity) are being redefined. Regulation of energy balance operates at both central nervous system and peripheral sites, including adipose and liver. For example, the endocannabinoid system could potentially be modulated to provide effective pharmacotherapy of NAFLD. The more profound the metabolic abnormalities complicating over-nutrition (glucose intolerance, hypoadiponectinemia, metabolic syndrome), the more likely is NAFLD to take on its progressive guise of non-alcoholic steatohepatitis (NASH). Interactions between steatosis and insulin resistance, visceral adipose expansion and subcutaneous adipose failure (with insulin resistance, inflammation and hypoadiponectinemia) trigger amplifying mechanisms for liver disease. Thus, transition from simple steatosis to NASH could be explained by unmitigated hepatic lipid partitioning with failure of local adaptive mechanisms leading to lipotoxicity. In part one of this review, we discuss newer concepts of appetite and metabolic regulation, bodily lipid distribution, hepatic lipid turnover, insulin resistance and adipose failure affecting adiponectin secretion. We review evidence that NASH only occurs when over-nutrition is complicated by insulin resistance and a highly disordered metabolic milieu, the same 'metabolic movers' that promote type 2 diabetes and atheromatous cardiovascular disease. The net effect is accumulation of lipid molecules in the liver. Which lipids and how they cause injury, inflammation and fibrosis will be discussed in part two.

Influence of polygenetic polymorphisms on the susceptibility to non-alcoholic fatty liver disease of Chinese people

BACKGROUND AND AIM

The aim of this study was to investigate the influence of polygenetic polymorphisms, which play a role in the pathogenesis of metabolic syndrome, on the susceptibility to non-alcoholic fatty liver disease (NAFLD) of Chinese people.

METHODS

The subjects were selected from an epidemiological survey in the Guangdong province of southern China. In each polymorphism study, 50-117 subjects who met the diagnostic criteria of NAFLD and had typical clinical and ultrasonographic findings were placed into the case group. Using a nested case-control design, the same numbers of matched people without NAFLD were included as controls. Single nucleotide polymorphisms (SNP) at nine positions in seven candidate genes were tested. These SNP were found to be associated with the pathogenesis of metabolic syndrome. Genetic analyses were performed using genomic DNA extracted from peripheral blood leukocytes. Polymerase chain reaction-restriction fragment length polymorphism was applied to detect SNP.

RESULTS

Most candidate genes' SNP were associated with susceptibility to NAFLD. Some showed positive relationships (increased risk): tumor necrosis factor-alpha-238, adiponectin-45, leptin-2548, peroxisome proliferator-activated receptors-161 and phosphatidyletha-nolamine N-methyltransferase-175. Other SNP demonstrated a negative association (decreased risk): adiponectin-276 and hepatic lipase-514. Only two were not associated: tumor necrosis factor-alpha-380 and peroxisome proliferator-activated receptors-gamma co-activator-1alpha-482.

CONCLUSION

Most candidate genes' SNP examined in metabolic syndrome patients were associated with susceptibility to NAFLD.

Dynamic expression of hepatic thioredoxin mRNA in rats with non-alcoholic fatty liver disease

OBJECTIVE

To investigate the expression and significance of thioredoxin messenger ribonucleic acid (mRNA) in the development of non-alcoholic fatty liver disease (NAFLD) induced by a high fat diet.

METHODS

A total of 48 male Wistar rats were divided into a normal control group and a model group, which were both divided into three subgroups (at weeks 9, 13 and 18, respectively). The levels of serum tumor necrosis factor-alpha (TNF-alpha), free fatty acid (FFA), total cholesterol (TC) and triglyeride (TG), changes in the serum and hepatic tissue superoxide dismutase (SOD), reduced glutathione hormone (GSH) and malondialdehyde (MDA) were measured. The expression of thioredoxin mRNA in rat livers were detected with reverse transcriptase polymerase chain reaction (RT-PCR). Meanwhile, the pathological changes of liver tissue were observed by hematoxylin-eosin stain.

RESULTS

Simple fatty liver was observed in model group at week 9. From weeks 13 to 18, liver histopathology showed steatohepatitis. Compared with corresponding normal groups, in the model groups the levels of TNF-alpha, FFA, TC, TG in serum, and MDA in serum and liver increased significantly, while the vitality of SOD and GSH content in serum and liver decreased remarkably. Meanwhile, in the model group, the expression of hepatic thioredoxin mRNA was significantly decreased at week 9 compared with the normal group (P < 0.01), then increased gradually, but were lower than the corresponding normal groups at all times (P < 0.01).

CONCLUSION

The expression of thioredoxin mRNA is significantly lower in the liver of rats with NAFLD and might reach the lowest point after developing simple fatty liver. Meanwhile the downregulation of thioredoxin mRNA may cause the inflammatory injury initially in NAFLD.

Characterization of high-fat, diet-induced, non-alcoholic steatohepatitis with fibrosis in rats

An ideal animal model is necessary for a clear understanding of the etiology, pathogenesis, and mechanisms of human non-alcoholic steatohepatitis (NASH) and for facilitating the design of effective therapy for this condition. We aimed to establish a rat model of NASH with fibrosis by using a high-fat diet (HFD). Male Sprague-Dawley (SD) rats were fed a HFD consisting of 88 g normal diet, 10 g lard oil, and 2 g cholesterol. Control rats were fed normal diet. Rats were killed at 4, 8, 12, 16, 24, 36, and 48 weeks after HFD exposure. Body weight, liver weight, and epididymal fat weight were measured. Serum levels of fasting glucose, triglyceride, cholesterol, alanine aminotransferase (ALT), free fatty acids (FFA), insulin, and tumor necrosis factor-alpha (TNF-alpha) were determined. Hepatic histology was examined by H&E stain. Hepatic fibrosis was assessed by VG stain and immunohistochemical staining for transforming growth factor beta 1 (TGF-beta1), and alpha-smooth-muscle actin (alpha-SMA). The liver weight and liver index increased from week 4, when hepatic steatosis was also observed. By week 8, the body weight and epididymal fat weight started increasing, which was associated with increased serum levels of FFA, cholesterol, and TNF-alpha, as well as development of simple fatty liver. The serum ALT level increased from week 12. Steatohepatitis occurred from weeks 12 through 48. Apparent hepatic perisinosodial fibrosis did not occur until week 24, and progressed from week 36 to 48 with insulin resistance. Therefore, this novel model may be potentially useful in NASH study.

Review article: omega-3 fatty acids - a promising novel therapy for non-alcoholic fatty liver disease

BACKGROUND

Non-alcoholic fatty liver disease affects 10-35% of the adult population worldwide; there is no consensus on its treatment. Omega-3 fatty acids have proven benefits for hyperlipidaemia and cardiovascular disease, and have recently been suggested as a treatment for non-alcoholic fatty liver disease.

AIMS

To review the evidence base for omega-3 fatty acids in non-alcoholic fatty liver disease and critically appraise the literature relating to human trials.

METHODS

A Medline and PubMed search was performed to identify relevant literature using search terms 'omega-3', 'N-3 PUFA', 'eicosapentaenoic acid', 'docosahexaenoic acid', 'non-alcoholic fatty liver disease' and 'NAFLD'.

RESULTS

Omega-3 fatty acids are important regulators of hepatic gene transcription. Animal studies demonstrate that they reduce hepatic steatosis, improve insulin sensitivity and reduce markers of inflammation. Clinical trials in human subjects generally confirm these findings, but have significant design inadequacies.

CONCLUSIONS

Omega-3 fatty acids are a promising treatment for non-alcoholic fatty liver disease which require to be tested in randomized placebo-controlled trials.

Functional proteomic analysis of nonalcoholic fatty liver disease in rat models: enoyl-coenzyme a hydratase down-regulation exacerbates hepatic steatosis

Nonalcoholic fatty liver disease (NAFLD) has emerged as a common public health problem that can progress to end-stage liver disease. A high-fat diet (HFD) may promote the development of NAFLD through a mechanism that is poorly understood. We adopted a proteomic approach to examine the effect of HFD on the liver proteome during the progression of NAFLD. Male Sprague-Dawley rats fed an HFD for 4, 12, and 24 weeks replicated the progression of human NAFLD: steatosis, nonspecific inflammation, and steatohepatitis. Using two-dimensional difference gel electrophoresis (DIGE) combined with matrix-assisted laser desorption ionization time of flight/time of flight analysis, 95 proteins exhibiting significant changes (ratio > or = 1.5 or < or =-1.5, P < 0.05) during the development of NAFLD were identified. Biological functions for these proteins reflected phase-specific characteristics during the progression of the disease. The potential role of enoyl-coenzyme A hydratase (ECHS1), an enzyme that catalyzes the second step of mitochondrial fatty acid beta-oxidation, received further investigation. First, the reduced protein level of ECHS1 was validated both in rat models and in patients with biopsy-proven hepatic simple steatosis via immunoblotting or immunohistochemical analysis. Then the small interfering RNA (siRNA)-mediated knockdown of ECHS1 in the murine hepatocyte cell line alpha mouse liver 12 (AML12) demonstrated increased cellular lipid accumulation induced by free fatty acid (FFA) overload. Furthermore, using a hydradynamic transfection method, the in vivo silencing effect of siRNA duplexes targeting ECHS1 was further investigated in mice. Administering ECHS1 siRNA specifically reduced the expression of ECHS1 protein in mice liver, which significantly exacerbated the hepatic steatosis induced by an HFD.

CONCLUSION

Our results revealed that ECHS1 down-regulation contributed to HFD-induced hepatic steatosis, which may help clarify the pathogenesis of NAFLD and point to potential targets for therapeutic interventions.

Hepatic steatosis (fatty liver disease) in asymptomatic adults identified by unenhanced low-dose CT

OBJECTIVE

The purpose of this study was to investigate the prevalence of hepatic steatosis in an asymptomatic U.S. adult population using attenuation values at unenhanced CT as the reference standard. We also assessed the utility of known clinical risk factors for diagnosis.

MATERIALS AND METHODS

For 3,357 consecutive asymptomatic adults (1,865 women and 1,492 men; mean age, 57.0 years), hepatic and splenic CT attenuation values (Hounsfield units) were obtained by unenhanced CT using a low-dose colonography technique for colorectal cancer screening. Multiple attenuation criteria for steatosis were applied, including liver thresholds and comparison of liver and spleen attenuation. Relevant clinical risk factors were compared against a CT liver attenuation < or = 40 HU, which has been shown to exclude mild steatosis.

RESULTS

Mean liver attenuation was 58.8 +/- 10.8 (SD) HU. The prevalence of moderate-to-severe hepatic steatosis (defined by liver attenuation < or = 40 HU) was 6.2% (208/3,357). For CT attenuation criteria that include milder degrees of steatosis, prevalence increased to as high as 45.9% (1,542/3,357) for a liver-to-spleen attenuation ratio of < or = 1.1. Overweight status (body mass index > 25) was a sensitive indicator for moderate-to-severe steatosis (92.8%) but was highly nonspecific (37.5%). Other clinical risk factors, such as diabetes, dyslipidemia, hypertension, alcohol overuse, and hepatitis, were more specific (77.6-92.4%) but highly insensitive (1.9-37.5%). Combining clinical risk factors did not substantially increase the accuracy for screening.

CONCLUSION

Assessment of liver attenuation by use of unenhanced CT represents an objective and noninvasive means for detection of asymptomatic hepatic steatosis, whereas clinical risk factor assessment is unreliable. Further longitudinal investigation is needed to determine the most appropriate attenuation threshold and the risk for disease progression to steatohepatitis and cirrhosis.

Hepatitis B virus X protein impairs hepatic insulin signaling through degradation of IRS1 and induction of SOCS3

BACKGROUND

Hepatitis B virus (HBV) is a major cause of chronic liver diseases, and frequently results in hepatitis, cirrhosis, and ultimately hepatocellular carcinoma. The role of HCV in associations with insulin signaling has been elucidated. However, the pathogenesis of HBV-associated insulin signaling remains to be clearly characterized. Therefore, we have attempted to determine the mechanisms underlying the HBV-associated impairment of insulin signaling.

METHODOLOGY

The expressions of insulin signaling components were investigated in HBx-transgenic mice, HBx-constitutive expressing cells, and transiently HBx-transfected cells. Protein and gene expression was examined by Western blot, immunohistochemistry, RT-PCR, and promoter assay. Protein-protein interaction was detected by coimmunoprecipitation.

PRINCIPAL FINDINGS

HBx induced a reduction in the expression of IRS1, and a potent proteasomal inhibitor blocked the downregulation of IRS1. Additionally, HBx enhanced the expression of SOCS3 and induced IRS1 ubiquitination. Also, C/EBPalpha and STAT3 were involved in the HBx-induced expression of SOCS3. HBx interfered with insulin signaling activation and recovered the insulin-mediated downregulation of gluconeogenic genes.

CONCLUSIONS/SIGNIFICANCE

These results provide direct experimental evidences for the contribution of HBx in the impairment of insulin signaling.

Hepatic effects of rosiglitazone in rats with the metabolic syndrome

Rats given fructose-enriched diet develop many characteristics of the human metabolic syndrome and non-alcoholic fatty liver disease. In this study, we characterized the hepatic effects of rosiglitazone in fructose-enriched diet rats. Rats were randomly divided into three groups. One group was maintained on standard rat chow diet for 6 weeks, whereas the other two groups were given fructose-enriched diet for 6 weeks. Four weeks after the initiation of fructose-enriched diet, one of the fructose-enriched diet groups was also given rosiglitazone (10 mg/kg/day) for an additional 2 weeks. Rosiglitazone administration to the fructose-enriched diet rats was associated with decreases in the following parameters: blood pressure (-17%), plasma triglycerides (-62%), hepatic total lipids (-19%), hepatic triglycerides (-61%), hepatic malondialdehyde (-88%), glutathione reductase activity (-84%). An increase in adiponectin plasma levels (+329%), hepatic phospholipids (+46%), hepatic alpha-tocopherol concentrations (+24%) and hepatic paraoxonase activity (+68%) was observed. Rosiglitazone caused a decrease in hepatic macrovesicular steatosis score but no change in hepatic fibrosis. Administration of rosiglitazone, to rats with the metabolic syndrome has limited hepatic favourable effects: it improves hepatic lipid metabolism, decreases macrovesicular steatosis and improves some of the hepatic oxidative-anti-oxidative milieu but has no effect on hepatic fibrosis.

Treatment options for nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) has become increasingly recognized as the most common cause of abnormal liver enzymes in the last few decades and is among the most common forms of chronic liver disease in the Western world and across the globe. With the growing epidemic of obesity and diabetes, NAFLD is estimated to affect about one-quarter of the US population. Although most patients with NAFLD have nonprogressive bland steatosis, a minority of patients develop the histological subtype of nonalcoholic steatohepatitis (NASH), which may progress to cirrhosis, hepatocellular carcinoma, and liver-related death. This is especially true when NASH patients have type 2 diabetes. Treatment of NAFLD should therefore be directed towards patients with established NASH. Sustained weight loss seems to improve insulin resistance and associated NASH. In fact, weight loss with bariatric surgery leads to biochemical and histological improvement in morbidly obese patients with NASH. Several pharmacologic agents have been studied in an effort to improve insulin resistance and pro-inflammatory mediators potentially responsible for the development and progression of NASH. While some studies have shown initial promise, none has established long-term efficacy using randomized clinical trials. This paper briefly reviews the epidemiology, natural history, and pathophysiology of NAFLD and NASH and then focuses on the clinical trials of various therapeutic modalities for NAFLD. These include weight loss agents, bariatric surgery, insulin-sensitizing agents, lipid-lowering agents, antioxidants, probiotics, anti-tumor necrosis factor agents, cytoprotective and other novel agents.

Hepatitis B virus infection among American patients with chronic hepatitis C virus infection: prevalence, racial/ethnic differences, and viral interactions

Little is known about hepatitis B virus (HBV) infection among patients with chronic hepatitis C virus (HCV) infection in the United States. We prospectively enrolled 1,257 patients with chronic HCV infection from two medical centers in New York City. A total of 61.5% (95% confidence interval, 58.8%-64.2%) had evidence of prior exposure to HBV (hepatitis B core antibody-positive), whereas 5.8% (95% confidence interval, 4.5%-7.1%) had dual infection with HBV (hepatitis B surface antigen-positive). Multivariable logistic regression analysis identified age <40 years, Asian race, injection drug use, and a greater number of lifetime sexual partners as independent risk factors for HBV-HCV dual infection. Liver biopsy results in 26 HBV-HCV-infected and 658 HCV-monoinfected patients showed that stage 3 or 4 fibrosis was significantly more common in those with HBV-HCV dual infection (84.6% versus 29.9%; P < 0.001). Patients infected with HBV and HCV had significantly lower median HCV RNA levels (1.3 versus 4.5 x 10(6) copies/mL; P < 0.001) and were less likely to have HCV RNA levels > or =5 x 10(6) copies/mL (12.3% versus 45.4%; P < 0.001) than those who had HCV monoinfection. All five patients with HBV-HCV dual infection who had undetectable HBV DNA levels had HCV RNA levels > or =5 x 10(6) copies/mL.

CONCLUSION

American patients with chronic HCV infection should be tested for HBV, especially younger patients, Asians, injection drug users, and those with an increased number of lifetime sexual partners. The presence of severe liver disease and HBV-HCV viral interactions in patients with dual infection necessitates careful but aggressive clinical management, although the optimal strategy remains to be determined.

Nonalcoholic fatty liver disease: a review and update

The spectrum of nonalcoholic fatty liver disease (NAFLD) ranges from asymptomatic steatosis to nonalcoholic steatohepatitis (NASH) and cirrhosis. Hepatic steatosis occurs when free fatty acids, released in the setting of insulin resistance and the metabolic syndrome, are taken up by the liver. Additional biochemical insults, including oxidative stress, upregulation of inflammatory mediators, and dysregulated apoptosis, can result in inflammation (producing NASH) and fibrosis. Noninvasive methods (e.g., abdominal ultrasonography) are safe ways to support a diagnosis of hepatic steatosis, but advanced liver histopathologic findings including NASH and fibrosis cannot be identified without pursuing liver biopsy. Recent advances in serologic and imaging methods aim to determine severity of inflammation and fibrosis noninvasively. Currently, therapeutic options for NAFLD are limited to medications that reduce risk factors, but the future holds promise for therapies that might slow the progression of this increasingly prevalent disorder.

Relationship between uric acid and hepatic steatosis among Koreans

AIM

The relationship between high uric-acid levels and hepatic steatosis, according to body mass index (BMI) categories, and their coexistence with the metabolic syndrome (MetS) were examined in the present study.

METHODS

The study involved a cross-sectional sample of 13,621 Koreans (7221 men and 6400 women) who visited a health checkup centre between 2005 and 2006. Hepatic steatosis was diagnosed using ultrasonography. Hyperuricaemia was defined as >7mg/dL for men and >6mg/dL for women. The MetS was defined as the presence of three or more MetS components-obesity (BMI >or=25.0kg/m(2)), high blood pressure, elevated levels of triglycerides and glucose, and low levels of high-density lipoprotein (HDL)-cholesterol.

RESULTS

In total, 26.2% were diagnosed with hepatic steatosis, of whom 11.9% were non-obese (BMI <25kg/m(2)) and 52.5% were obese. Hyperuricaemia was associated with hepatic steatosis in non-obese (adjusted odds ratio [AOR] of 1.4 in men and 2.2 in women) as well as in obese individuals (AOR of 1.8 in men and 2.3 in women) after adjusting for age, other MetS components and liver function tests. The AOR (95% CI) for hepatic steatosis in obese individuals with hyperuricaemia compared with non-obese individuals with normal uric-acid levels was 7.7 (6.4-9.3) in men and 12.4 (7.8-19.5) in women. The adjusted age and liver-function test ORs (95% CI) for hepatic steatosis in those with hyperuricaemia and no MetS compared with those who had normal uric acid levels and no MetS were 2.0 (1.7-2.4) in men and 3.2 (2.1-4.9) in women. The ORs (95% CI) in those with hyperuricaemia and the MetS increased to 6.9 (5.5-8.8) and 15.2 (8.4-27.4) in men and women, respectively.

CONCLUSION

Hyperuricaemia is independently associated with hepatic steatosis regardless of BMI category or the presence of the MetS in Korean adults. Further research into the causal relationship is needed.

Betaine inhibits Toll-like receptor 4 expression in rats with ethanol-induced liver injury

AIM: To test whether ethanol feeding could induce Toll-like receptor 4 (TLR4) responses, assess the hepatoprotective effect of betaine and its inhibitive effect on TLR4 in animal models of alcoholic liver injury.

METHODS: Forty-eight female Sprague-Dawley rats were randomly divided into four groups as control, model, low and high dose betaine groups. Except control group, all rats were fed with high fat-containing diet plus ethanol and fish oil gavages for 8 wk. Betaine was administered intragastrically after exposure of ethanol for 4 wk. The changes of liver histology were examined. The expression of TLR4 mRNA and protein was detected by RT-PCR and Western blotting, respectively. The serum aminotransferase activity [alanine transarninase (ALT), aspartate aminotransferase (AST)], serum endotoxin, and liver inflammatory factors [tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), interleukin-18 (IL-18)] were also assayed.

RESULTS: Compared with control group, rats of model group developed marked liver injury, accompanied by an increase of ALT (159.41 ± 7.74 U/L vs 59.47 ± 2.34 U/L, P < 0.0001), AST (248.25 ± 1.40 U/L vs 116.89 ± 3.48 U/L, P < 0.0001), endotoxin (135.37 ± 30.17 ng/L vs 44.15 ± 7.54 ng/L, P < 0.0001), TNF-α (20.81 ± 8.58 pg/mL vs 9.34 ± 2.57 pg/mL, P = 0.0003), IFN-γ (30.18 ± 7.60 pg/mL vs 16.86 ± 9.49 pg/mL, P = 0.0039) and IL-18 (40.99 ± 8.25 pg/mL vs 19.73 ± 9.31 pg/mL, P = 0.0001). At the same time, the expression of TLR4 mRNA and protein was markedly induced in the liver after chronic ethanol consumption (1.45 ± 0.07 vs 0.44 ± 0.04, P < 0.0001; 1.83 ± 0.13 vs 0.56 ± 0.08, P < 0.0001). Compared with model group, betaine feeding resulted in significant decreases of ALT (64.93 ± 6.06 U/L vs 159.41 ± 7.74 U/L, P < 0.0001), AST (188.73 ± 1.11 U/L vs 248.25 ± 1.40 U/L, P < 0.0001), endotoxin (61.80 ± 12.56 ng/L vs 135.37 ± 30.17 ng/L, P < 0.0001), TNF-α (9.79 ± 1.32 pg/mL vs 20.81 ± 8.58 pg/mL, P = 0.0003), IFN-γ (18.02 ± 5.96 pg/mL vs 30.18 ± 7.60 pg/mL, P = 0.0008) and IL-18 (18.23 ± 7.01 pg/mL vs 40.99 ± 8.25 pg/mL, P < 0.0001). Betaine also improved liver steatosis. The expression levels of TLR4 mRNA or protein in liver tissues were significantly lowered (0.62 ± 0.04 vs 1.45 ± 0.07, P < 0.0001; and 0.65 ± 0.06 vs 1.83 ± 0.13, P < 0.0001). There was a statistical difference of TLR4 mRNA and protein expression between high- and low-dose betaine groups (0.62 ± 0.04 vs 0.73 ± 0.05, P < 0.0001, and 0.65 ± 0.06 vs 0.81 ± 0.09, P < 0.0001).

CONCLUSION: Betaine can prevent the alcohol-induced liver injury effectively and improve the liver function. The expression of TLR4 increases significantly in ethanol-fed rats and betaine administration can inhibit TLR4 expression.

Non-alcoholic fatty liver disease: the hepatic consequence of obesity and the metabolic syndrome

Non-alcoholic fatty liver disease (NAFLD) is now the most common liver disease in both adults and children worldwide. As a disease spectrum, NAFLD may progress from simple steatosis to steatohepatitis, advanced fibrosis and cirrhosis. An estimated 20–35% of the general population has steatosis, 10% of whom will develop the more progressive non-alcoholic steatohepatitis associated with markedly increased risk of cardiovascular- and liver-related mortality. Development of NAFLD is strongly linked to components of the metabolic syndrome including obesity, insulin resistance, dyslipidaemia and type 2 diabetes. The recognition that NAFLD is an independent risk factor for CVD is a major public health concern. There is a great need for a sensitive non-invasive test for the early detection and assessment of the stage of NAFLD that could also be used to monitor response to treatment. The cellular and molecular aetiology of NAFLD is multi-factorial; genetic polymorphisms influencing NAFLD have been identified and nutrition is a modifiable environmental factor influencing NAFLD progression. Weight loss through diet and exercise is the primary recommendation in the clinical management of NAFLD. The application of systems biology to the identification of NAFLD biomarkers and factors involved in NAFLD progression is an area of promising research.

The prevalence and clinical correlates of elevated ALT levels in an urban Chinatown community

Alanine aminotransferase (ALT) levels are a primary consideration in treatment decisions regarding hepatitis B virus (HBV) infection. Levels can be elevated as a result of HBV-related liver injury or to other causes. The aim of this study was to assess the background prevalence and clinical correlates of elevated ALT levels in Chinese immigrants who were HBsAg negative. Subjects consisted of adults seen in an urban Chinatown Internal Medicine practice between 1, 2006 and 12, 2007. Clinical information was collected retrospectively. An elevated ALT level was defined as >19 U/L for women and >30 U/L for men. The primary analysis focused on 2457 persons who were HBsAg negative. Their mean age was 55 +/- 18 years, 64% were female and 36% were obese. All subjects were ethnically Chinese and 96% were born in Asia. Thirty percent had an elevated ALT level. In univariate analysis, factors associated with elevated ALT included older age (P < 0.001), female gender (P = 0.001), obesity (P < 0.001), diabetes (P < 0.001), hypercholesterolemia (P < 0.001) and hypertension (P < 0.001). In multivariate analysis BMI, diabetes, female gender and hypercholesterolemia were significantly associated with elevated ALT level. An additional analysis focused on a group of patients who were HBsAg positive, HBeAg negative and had HBV-DNA levels <1000 copies/mL. Fifty percent had elevated ALT levels. In conclusion, elevated ALT levels are common among Chinese immigrants without HBV (30%) and are associated with features of the metabolic syndrome. Liver biopsy should be performed in selected patients with HBV to distinguish the cause of ALT elevation before initiating antiviral therapy.

Continuous positive airway pressure improves sleep apnea associated fatty liver

Treatment of sleep apnea can improve liver enzyme abnormalities in patients with nonalcoholic fatty liver disease. However, the effect of continuous positive airway pressure therapy for sleep apnea on liver fat accumulation was not assessed. Liver biopsy is the "gold standard" for determining and quantifying liver fat accumulation; however, obtaining two separate liver biopsies is challenging. We examined, using a newly described computerized tomography method to quantify liver fat accumulation, whether treatment of sleep apnea improves liver steatosis. In a prospective cohort study, patients diagnosed with obstructive sleep apnea, at Assaf Harofeh Medical Center's sleep laboratory, were identified. Patients completed a questionnaire and underwent blood tests for liver enzymes and lipid profile, and computed tomography scans to determine the liver attenuation index. Patients with liver attenuation index <or=-10 (correlating with histological macrovesicular steatosis >or=30%) were treated with continuous positive airway pressure for 2-3 years. Subsequently, patients underwent repeat blood tests and tomography scans. Of 47 patients who were analyzed, 16 had a low liver attenuation index (<or=-10). Patients with moderate-severe sleep apnea had worse liver attenuation index compared with patients with mild sleep apnea despite comparable body mass index and triglycerides levels. Patients who were compliant with 2-3 years of continuous positive airway pressure treatment demonstrated significant improvement in the mean liver attenuation index, whereas noncompliant patients did not. Patients with nonalcoholic fatty-liver disease may benefit from identification and treatment for obstructive sleep apnea because treatment may improve liver steatosis.

Interaction of adipokines and hepatitis B virus on histological liver injury in the Chinese

OBJECTIVES

Chronic hepatitis B patients with diabetes and metabolic syndrome are at increased risk of cirrhosis and hepatocellular carcinoma, but the underlying mechanism is unclear. Our objective was to test whether dysregulation of adipokines contributes to liver injury. We also studied whether viral factors affected adipokines, insulin resistance, and hepatic steatosis.

METHODS

A prospective cohort of 266 chronic hepatitis B patients undergoing liver biopsy was studied. Fasting blood was taken for the analysis of tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), adiponectin, leptin, and resistin. Insulin resistance was assessed by the homeostasis model assessment of insulin resistance (HOMA-IR). Factors associated with significant necroinflammation and cirrhosis were identified.

RESULTS

Histological activity index was correlated with serum TNF-alpha (R=0.40, P<0.0001) and IL-6 (R=0.32, P<0.0001) but not with adiponectin, leptin, or resistin. By multivariate analysis, TNF-alpha was associated with significant necroinflammation after adjusting for age and viral factors (odds ratio (OR) 1.041, 95% confidence interval (CI) 1.002-1.082, P=0.04). Serum adiponectin had positive correlation with hepatitis B virus DNA (R=0.17, P=0.007) and was decreased in patients with insulin resistance and hepatic steatosis. On the other hand, viral load, hepatitis B e-antigen status, and genotypes had no association with insulin resistance, hepatic steatosis, and the levels of TNF-alpha and IL-6. A total of 68 (25.6%) patients had cirrhosis. HOMA-IR, but not adipokine dysregulation, was independently associated with cirrhosis (OR 1.09, 95% CI 1.02-1.15, P=0.006).

CONCLUSIONS

TNF-alpha and/or IL-6 contribute to hepatic necroinflammation in chronic hepatitis B patients. Adiponectin protects against insulin resistance and hepatic steatosis but does not affect liver injury. Adipokines and viral factors contribute to liver injury independently.

Prevalence and factors associated with the presence of nonalcoholic fatty liver disease in an adult population in Spain

BACKGROUND/AIMS

The prevalence of nonalcoholic fatty liver disease (NAFLD) is unknown in Spain. The purpose of detecting NAFLD patients is to determine the associated factors and prevent its evolution to more severe forms. The aim of this study is to determine the prevalence and factors associated with NAFLD.

METHODS

This is a multicentre, cross-sectional, populational study. Individuals between 15 and 85 years of age were randomly selected from 25 primary healthcare centres in the province of Barcelona, Spain. Clinical histories were reviewed, and anamnesis, physical examination, blood analysis and hepatic echography were performed. Individuals with an alcohol intake greater than 30 g/day in men and greater than 20 g/day in women or with known liver disease were excluded.

RESULTS

Seven hundred and sixty-six individuals with a mean age of 53+/-14 years (range 17-83, 42.2% men) were included in the study. One hundred and ninety-eight individuals presented NAFLD with echographic criteria (prevalence 25.8, 33.4% men and 20.3% women P<0.001). On multivariate analysis, the following were associated with NAFLD: male sex [odds ratio (OR): 2.34, 95% confidence interval (95% CI): 1.57-3.49], age (OR: 1.04 per year, 95% CI: 1.02-1.05), metabolic syndrome (OR: 2.19, 95% CI: 1.29-3.72), insulin resistance (OR: 6.00, 95% CI: 3.43-10.5) and alanine aminotransferase (OR: 4.21, 95% CI: 2.23-7.95). Of the individuals who consumed alcohol, 29.4% consumed alcohol within the inclusion criteria, with a mean of 9.17+/-6.75 standard beverage units per week. Moderate alcohol intake was not related to NAFLD, although a possible protector effect was found with the quantity consumed among the drinkers who did not consume excessive amounts of alcohol (OR: 0.93 per standard beverage units, 95% CI: 0.88-0.98).

CONCLUSION

NAFLD prevalence in our population is very high. Male sex, age, metabolic syndrome, insulin resistance and alanine aminotransferase are the factors associated with NAFLD. Furthermore, studies should be carried out with respect to the controversial effect of alcohol on NAFLD.

Multivariate analysis of risk factors for the development of type 2 diabetes in nonalcoholic fatty liver disease

PURPOSE

Diabetes is present in patients with nonalcoholic fatty liver disease (NAFLD). The aim of this retrospective cohort study was to assess the cumulative development of type 2 diabetes and predictive factors for its development in Japanese patients with NAFLD.

METHODS

A total of 6003 NAFLD patients diagnosed by ultrasonography were enrolled. The mean follow-up period was 4.9 years. An overnight (12 h) fasting blood sample or a casual blood sample was taken for routine analyses during follow up. The primary outcome was the development of type 2 diabetes. Evaluation was performed by using the Kaplan-Meier method and Cox proportional hazards analysis.

RESULTS

Of the 6003 NAFLD patients, 411 patients developed type 2 diabetes. The cumulative development rate of type 2 diabetes was 6.8% at the 5th year and 17.7% at the 10th year. Multivariate Cox proportional hazards analysis showed that type 2 diabetes development in patients with NAFLD occurred when patients had prediabetes status (hazard ratio 6.39; 95% confidence interval 5.00-8.18; P < 0.001), mean serum gamma-glutamyltransferase (GGT) level of more than 109 IU/l (hazard ratio 1.60; 95% confidence interval 1.22-2. 02; P < 0.001), mean serum triglyceride (TG) level of more than 150 mg/l (hazard ratio 1.28; 95% confidence interval 1.05-1.55; P = 0.020), and physical activity of less than 60 min per week (hazard ratio 1.60; 95% confidence interval 1.25-2.00; P < 0.001).

CONCLUSIONS

The improvement of prediabetes status and physical activity, and the normalization of mean GGT and TG levels during follow up are important to prevent the development of T2DM in patients with NAFLD.

Tissue factor-deficiency and protease activated receptor-1-deficiency reduce inflammation elicited by diet-induced steatohepatitis in mice

Altered hepatic lipid homeostasis, hepatocellular injury, and inflammation are features of nonalcoholic steatohepatitis, which contributes significantly to liver-related morbidity and mortality in the Western population. A collection of inflammatory mediators have been implicated in the pathogenesis of steatohepatitis in mouse models. However, the pathways essential for coordination and amplification of hepatic inflammation and injury caused by steatosis are not completely understood. We tested the hypothesis that tissue factor (TF)-dependent thrombin generation and the thrombin receptor protease activated receptor-1 (PAR-1) contribute to liver inflammation induced by steatosis in mice. Wild-type C57Bl/6J mice fed a diet deficient in methionine and choline for 2 weeks manifested steatohepatitis characterized by increased serum alanine aminotransferase activity, macrovesicular hepatic steatosis, hepatic inflammatory gene expression, and lobular inflammation. Steatohepatitis progression was associated with thrombin generation and hepatic fibrin deposition. Coagulation cascade activation was significantly reduced in low TF mice, which express 1% of normal TF levels. Hepatic triglyceride accumulation was not affected in low TF mice or PAR-1-deficient mice. In contrast, biomarkers of hepatocellular injury, inflammatory gene induction, and hepatic accumulation of macrophages and neutrophils were greatly reduced by TF-deficiency and PAR-1-deficiency. The results suggest that TF-dependent thrombin generation and activation of PAR-1 amplify hepatic inflammation and injury during the pathogenesis of steatohepatitis.

Metabolic syndrome and alanine aminotransferase: a global perspective from the NAVIGATOR screening population

AIMS

Non-alcoholic fatty liver disease (NAFLD) is associated with features of the metabolic syndrome (MetS) and may be an expression of the syndrome within the liver. Using screening data from the Nateglinide And Valsartan in Impaired Glucose Tolerance Outcomes Research (NAVIGATOR) study (n = 42 149), we examined whether alanine aminotransferase (ALT), a biomarker for NAFLD, clustered with features of MetS and whether the clusters differed across global geographic regions.

METHODS

Exploratory factor analysis using principle components analysis was applied to data drawn from the NAVIGATOR screening population (n = 41 111). Demographic data, anthropomorphic measurements and blood pressure (BP) collected during the screening visit, as well as blood samples analysed for ALT, total cholesterol, triglycerides, high-density lipoprotein, low-density lipoprotein, and fasting and 2-h glucose measures after an oral glucose tolerance test were used for our analysis.

RESULTS

Two factors, interpreted as lipid (Factor 1), and BP/obesity (Factor 2) were identified, explaining approximately 50% of the variance in the overall population. Similar patterns of aggregation were reproducible across all geographic regions except Asia, where fasting glucose loaded more consistently on Factor 1. ALT loaded with mean arterial pressure, fasting glucose and waist circumference except in Asia, where it loaded only with mean arterial pressure and waist circumference.

CONCLUSIONS

ALT aggregated with components of MetS, and the pattern of aggregation of ALT with other features of MetS was similar across regions except Asia, possibly indicating a different pathophysiology for NAFLD in Asia. Predictive models of NAFLD may need to be adjusted for regional and ethnic differences.

Therapeutic effects of diet change on nonalcoholic fatty liver disease

AIM: To investigate the therapeutic effects of diet change on nonalcoholic fatty liver disease (NAFLD) and explore potential mechanisms involved.

METHODS: Eighty Sprague-Dawley male rats were randomly and equally divided into five groups: two normal control groups (NG8 and NG12 groups; fed a normal diet for 8 and 12 weeks, respectively), two high-fat diet groups (HG8 and HG12 groups; fed a high-fat diet for 8 and 12 weeks, respectively), and one diet change group (DG group; fed a high-fat diet for 8 weeks and a normal diet for another 4 weeks). The glucose infusion rate (GIR) was detected by the euglycemic hyperinsulinemic clamp test. The levels of ALT, AST, TG, TC, FFAs, FBS, FIns, TNF-α, SOD and MDA in the serum or liver were tested using a biochemistry automatic analyzer or by radioimmunoassay (RIA). The expression of c-Jun N-terminal protein kinase 1 (JNK1), insulin receptor substrate-1 (IRS-1) and phospho-IRS-1 Ser307 (p-IRS-1Ser307) was detected by Western blot.

RESULTS: Compared with the two matched NG groups, the body weight, liver index, the levels of ALT, AST, TG, TC, FFAs, FIns and TNF-α in the serum and TG, TC, FFAs and MDA in the liver increased (all P < 0.05 or 0.01), the level of SOD in the liver and GIR decreased (t = 4.88 and 7.92, respectively; both P < 0.05), and the expression of JNK1 protein and p-IRS-1Ser307 in the liver was upregulated in the two HG groups (t = 4.39, 5.81; 4.60, and 6.48, respectively). Significant differences were also noted in the above parameters between the HG8 and HG12 groups (all P < 0.05 or 0.01). A positive correlation was found between the expression intensity of JNK1 and insulin resistance (IR). The fatty degeneration of hepatocytes was aggravated in the HG groups with the prolongation of feeding time. In the DG group, all the above parameters were improved but did not return to normal levels as those in the NG groups (all P < 0.05).

CONCLUSION: A rat model of NAFLD and a rat model of NASH are established by feeding rats a high-fat diet for 8 weeks and 12 weeks, respectively. Diet change can improve NAFLD induced by a high fat diet.

Synergistic effect of fatty liver and smoking on metabolic syndrome

AIM: To investigate the association of fatty liver and smoking on metabolic syndrome and its components.

METHODS: This cross-sectional study enrolled participants who attended annual health screening at Shin Kong Wu Ho-Su Memorial Hospital from January to December 2005. A total of 3455 (1981 men and 1474 women) subjects were included in final analyses. Fatty liver was diagnosed using abdominal ultrasonography by trained gastroenterologists. The modified National Cholesterol Education Program Adult Treatment Panel III was used to define metabolic syndrome. The associations between smoking, fatty liver and metabolic syndrome were analyzed using multiple logistic regression.

RESULTS: Subjects with fatty liver, and who smoked tobacco, had the highest odds ratios (ORs) for high waist circumference [OR, 4.5 (95% CI: 3.3-6.1), P < 0.05], hypertriglyceridemia [OR, 8.1 (95% CI: 6.0-10.9), P < 0.05], low serum high-density lipoprotein cholesterol (HDL-C) [OR, 8.3 (95% CI: 6.1-11.3), P < 0.05], and metabolic syndrome [OR, 9.5 (95% CI: 6.7-13.4), P < 0.05] compared to subjects without fatty liver who did not smoke tobacco. We also found that the ORs for hypertriglyceridemia, low serum HDL-C, and metabolic syndrome for subjects with fatty liver who smoked tobacco had greater than the sum of the ORs for subjects with fatty liver who did not smoke plus those who did not have fatty liver and who did smoke.

CONCLUSION: Fatty liver and smoking had a synergistic effect on metabolic syndrome and its components, especially for hypertriglyceridemia and low serum HDL-C.

Recent advances in understanding the pathogenesis of nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH) is a pathological condition characterized by macrovesicular steatosis, necroinflammation, loss of hepatocytes and fibrosis. NASH is often associated with type 2 diabetes mellitus, hypertension, hyperlipoproteinemia and obesity. Recent studies emphasize the role of insulin resistance, oxidative stress and subsequent lipid peroxidation, proinflammatory cytokines, adipokines and mitochondrial dysfunction in the development and progression of NASH. In this article, we will review the role of insulin resistance, oxidative stress and subsequent lipid peroxidation, mitochondrial dysfunction, proinflammatory cytokines, adipokines such as resistin, leptin, adiponectin and PPAR-α, apoptosis, NF kappa B, SREBP-1c, endotoxaemia, and iron overload in the pathogenesis of NASH. The pathogenesis of NASH is thought to be related mainly with insulin resistance and oxidative stress and subsequent lipid peroxidation. Adipocytokines also play an important role in the pathogenesis of NASH through complex and interactive paracrine and endocrine mechanisms. Understanding of the mechanisms responsible for the pathogenesis of NASH has important implications for the treatment of NASH.

Epidemiology and natural history of non-alcoholic steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver condition in many parts of the world. This article describes the epidemiology and natural history of this disorder. It also describes current diagnostic and treatment methods and describes future implications NAFLD may have.

Nonalcoholic fatty liver disease in children living in the obeseogenic society

BACKGROUND

The problem of obesity in children has grown considerably in recent years in the United States as well as the rest of the world. This has resulted in a marked increase in the prevalence of nonalcoholic liver disease in the pediatric age group. Nonalcoholic fatty liver disease (NAFLD) is currently the most common hepatic disorder seen in pediatric hepatology practice.

DATA SOURCES

We have reviewed the most recent literature regarding the prevalence, pathogenesis as well as the most recent advances in the diagnostic and therapeutic modalities of NAFLD in children.

RESULTS

NAFLD affects a substantial portion of the population including children.

CONCLUSIONS

The rising incidence of NAFLD, nonalcoholic steatohepatitis (NASH) and cirrhosis emphasizes the need for effective treatment options. The lack of complete understanding of the pathogenesis of NAFLD still limits our ability to develop novel therapeutic modalities that can target the metabolic derangements implicated in the development of the disorder.

Nonalcoholic fatty liver disease: quantitative assessment of liver fat content by computed tomography, magnetic resonance imaging and proton magnetic resonance spectroscopy

OBJECTIVE

The purpose of this study was to evaluate the clinical application of imaging technology in the quantitative assessment of fatty liver with magnetic resonance imaging (MRI) and proton MR spectroscopy.

METHODS

Overall 36 patients with diffuse fatty liver who had undertaken the computed tomography (CT) scan, MRI and proton MR spectroscopy (1H MRS) were analyzed. Their body mass index (BMI) was measured and their liver to spleen CT ratio (L/S) calculated on the plain CT scan. MR T1-weighted imaging (T1WI) was obtained with in-phase (IP) and out-of-phase (OP) images. T2-weighted imaging (T2WI) was acquired with or without the fat-suppression technique. The liver fat content (LFC) was quantified as the percentage of relative signal intensity loss on T1WI or T2WI images. The intrahepatic content of lipid (IHCL) was expressed as the percentage of peak value ratio of lipid to water by 1H MRS.

RESULTS

The results of BMI measurement, CT L/S ratio, LFC calculated from MR T1WI and T2WI images, as well as IHCL measured by 1H MRS were 27.26 +/- 3.01 kg/m2, 0.88 +/- 0.26, 13.80 +/- 9.92%, 40.67 +/- 16.04% and 30.98 +/- 20.43%, respectively. The LFC calculated from MR T1WI, T2WI images and IHCL measured by 1H MRS correlated significantly with the CT L/S ratio (r = -0.830, P = 0.000; r = -0.736, P = 0.000; r = -0.461, P = 0.005, respectively). BMI correlated significantly only with the liver fat contents measured by T1WI IP/OP and 1H MRS (r = -0.347, P = 0.038; r = -0.374, P = 0.025, respectively).

CONCLUSION

CT, MR imaging and 1H MRS were effective methods for the quantitative assessment of LFC. The MR imaging, especially 1H MRS, would be used more frequently in the clinical evaluation of fatty liver and (1)H MRS could more accurately reflect the severity of fatty liver.

Non-alcoholic fatty liver disease: an expanding problem with low levels of awareness in Hong Kong

BACKGROUND AND AIM

With the Westernization of the lifestyle and the rising prevalence of obesity and diabetes mellitus, non-alcoholic fatty liver disease (NAFLD) is an emerging health problem in the Asia-Pacific region. The purpose of this study was to determine the awareness of NAFLD among the general population in Hong Kong.

METHODS

A random telephone survey was conducted from September 2007 to January 2008 using a structured multiple-choice questionnaire. Subjects were Hong Kong residents aged 18 or above who spoke Cantonese.

RESULTS

In the first phase of the telephone survey, 521 subjects were interviewed and the results showed that as high as 83% of respondents had never come across the term 'NAFLD'. Upon completion of the second phase telephone survey, a total of 508 respondents who had heard of NAFLD were successfully interviewed. Of the 508 respondents, nearly half of them (42%) expressed no idea about the prevalence of NAFLD in Hong Kong. About half of respondents (47%) knew nothing about the clinical presentation of NAFLD. The majority of them (78%) had a misconception that blood tests could provide a definite diagnosis of NAFLD. Smoking, hepatitis B carriage and a past history of hepatitis A infection were cited as risk factors of NAFLD by 52%, 57% and 42% of respondents, respectively. Of the 508 respondents who had heard of NAFLD, most of them perceived that their knowledge of NAFLD was either inadequate (46%) or highly inadequate (35%).

CONCLUSION

This survey revealed an inadequate knowledge of NAFLD among the general population in Hong Kong.

Development of nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) after pancreaticoduodenectomy: proposal of a postoperative NAFLD scoring system

BACKGROUND

The main etiology of NAFLD and NASH after pancreatic resection is still unclear, and the therapeutic strategy has yet to be established. The focus of this review is how predict and prevent NAFLD/NASH after pancreaticoduodenectomy.

METHODS

From April 2005 to October 2008, 54 patients who underwent pancreaticoduodenectomy in our institution were enrolled in this study. From the pre-, intra- and postoperative risk factors, we identified the most influential risk factors of postoperative NAFLD by uni- and multivariate analyses. Moreover, a postoperative NAFLD scoring system was proposed based on these risk factors.

RESULTS

The incidence of postoperative NAFLD was 37.0% (20/54). Of these, 10% (2/20) of patients were diagnosed as having NASH by percutaneous liver biopsy. By multivariate analysis, pancreatic adenocarcinoma (p < 0.05), pancreatic resection line (p < 0.01) and postoperative diarrhea (p < 0.01) were identified as the most influential factors concerning postoperative NAFLD. Based on these results, we proposed a postoperative NAFLD scoring system (0-10) and evaluated the correlation between the score and decreasing rates of CT values, revealing a significant correlation (r = 0.829 p < 0.001). The prevalence of postoperative NAFLD in the patients with our scores of 0-3, 4-6 and 7-10 points was 0 (0/22), 35 (6/17) and 93% (14/15), respectively.

CONCLUSIONS

In conclusion, NAFLD develops frequently in patients who undergo PD, and some patients even progress to NASH. A postoperative NAFLD scoring system makes it possible to predict the occurrence of NAFLD after PD, and aggressive nutrition support is needed for patients with high scores.

The liver and the waistline: Fifty years of growth

Fifty years of the Gastroenterological Society of Australia have witnessed the changing appearance of Australians. Asian immigration has transformed the dominant urban culture from European to Eurasian, with some unique Australian attributes. Meanwhile, global conditions have altered body shape, and our sports-proud country is now fat! Thus, as in North America, Europe, China, and affluent Asia-Pacific countries, prosperity and lifestyle, cheap processed foods coupled with reduced physical activity have created an epidemic of over-nutrition resulting in overweight/obesity. Additional genetic factors are at the core of the apple shape (central obesity) that typifies over-nourished persons with metabolic syndrome. Indigenous Australians, once the leanest and fittest humans, now have exceedingly high rates of obesity and type 2 diabetes, contributing to shorter life expectancy; Asian Australians are also at higher risk. Like non-steroidal anti-inflammatory drugs (NSAIDs) and cigarette smoking, obesity now contributes much to gastrointestinal morbidity and mortality (gastroesophageal reflux disease, cancers, gallstones, endoscopy complications). This review focuses on Australian research about fatty liver, particularly roles of central obesity/insulin resistance in non-alcoholic fatty liver disease/steatohepatitis (NAFLD/NASH). The outputs include many highly cited original articles and reviews and the first book on NAFLD. Studies have identified community prevalence, clinical outcomes, association with insulin resistance, metabolic syndrome and hypoadiponectinemia, developed and explored animal models for mechanisms of inflammation and fibrosis, conceptualized etiopathogenesis, and demonstrated that NASH can be reversed by lowering body weight and increasing physical activity. The findings have led to development of regional guidelines on NAFLD, the first internationally, and should now inform daily practice of gastroenterologists.

Roles of adipose restriction and metabolic factors in progression of steatosis to steatohepatitis in obese, diabetic mice

BACKGROUND AND AIMS

We previously reported that steatohepatitis develops in obese, hypercholesterolemic, diabetic foz/foz mice fed a high-fat (HF) diet for 12 months. We now report earlier onset of steatohepatitis in relation to metabolic abnormalities, and clarify the roles of dietary fat and bodily lipid partitioning on steatosis severity, liver injury and inflammatory recruitment in this novel non-alcoholic steatohepatitis (NASH) model.

METHODS

Foz/foz (Alms1 mutant) and wild-type (WT) mice were fed a HF diet or chow, and metabolic characteristics and liver histology were studied at 2, 6, 12 and 24 weeks.

RESULTS

After 12 weeks HF-feeding, foz/foz mice were obese and diabetic with approximately 70% reduction in serum adiponectin. Hepatomegaly developed at this time, corresponding to a plateau in adipose expansion and increased adipose inflammation. Liver histology showed mild inflammation and hepatocyte ballooning as well as steatosis. By 24 weeks, HF-fed foz/foz mice developed severe steatohepatitis (marked steatosis, alanine aminotransferase elevation, ballooning, inflammation, fibrosis), whereas dietary and genetic controls showed only simple steatosis. While steatosis was associated with hepatic lipogenesis, indicated by increased fatty acid synthase activity, steatohepatitis was associated with significantly higher levels of CD36, indicating active fatty acid uptake, possibly under the influence of peroxisome proliferator-activated receptor-gamma.

CONCLUSION

In mice genetically predisposed to obesity and diabetes, HF feeding leads to restriction of adipose tissue for accommodation of excess energy, causing lipid partitioning into liver, and transformation of simple steatosis to fibrosing steatohepatitis. The way in which HF feeding 'saturates' adipose stores, decreases serum adiponectin and causes hepatic inflammation in steatohepatitis may provide clues to pathogenesis of NASH in metabolic syndrome.