Nonalcoholic fatty liver disease: a review of current understanding and future impact

Evaluation of the nonalcoholic fat liver disease fibrosis score for patients undergoing bariatric surgery

CONTEXT: Morbidly obese patients have an increased risk for nonalcoholic fat liver disease. Its severe form, nonalcoholic steatohepatitis may cause liver fibrosis. The diagnosis of advanced fibrosis has great value during the pre operative evaluation for bariatric surgery. Currently, liver biopsy is the gold standard for diagnosis of liver fibrosis. OBJECTIVE: To evaluate the nonalcoholic fat liver disease fibrosis score in morbidly obese patients undergoing Roux-en-Y gastric bypass in our population. METHODS: One hundred fifty-eight morbidly obese patients that had undergone bariatric surgery were included. Age, body mass index, hyperglycemia, platelet count, albumin and AST/ALT ratio were applied to the score formula. Scores above 0.676 were indicative of advanced liver fibrosis and scores under -1,455 absence of advanced liver fibrosis. These scores were compared to liver biopsy findings. RESULTS: The presence of advanced fibrosis could be diagnosed with good accuracy, with a positive predictive value of 83.7%. The score had a higher accuracy to exclude advanced fibrosis with a negative predictive value of 97%. Twenty-five patients (16%) had scores between the cutoffs points and were identified as indeterminate. The score sensibility and specificity was 83% and 97% respectively. CONCLUSIONS: The nonalcoholic fat liver disease fibrosis score has high accuracy to identify and exclude advanced liver fibrosis in morbidly obese patients subjected to bariatric surgery.

Dynamic expression of L-FABP and PPAR-α mRNAs in nonalcoholic fatty liver disease in rats

AIM: To establish a rat model of nonalcoholic fatty liver disease (NAFLD) to detect the changes in the expression of liver fatty acid-binding protein (L-FABP) and peroxisome proliferator-activated receptor-α (PPAR-α) mRNAs in NAFLD and to explore the mechanism underlying the pathogenesis of the disease.

METHODS: Eighty-four male Wistar rats were randomly and equally divided into two groups: control group (fed a normal diet for 18 weeks) and model group (fed a high-fat diet for 12 wk and a normal diet for another 6 wk). Each group was further divided into 7 subgroups for testing at weeks 0, 2, 4, 8, 12, 16 and 18. Rats in the two groups were sacrificed at each time point. Blood samples were taken to measure serum ALT, TG, CHOL, HDL-C and LDL-C. Liver samples were taken for HE staining and for detection of the expression of L-FABP and PPAR-α mRNAs by real-time fluorescence quantitative RT-PCR.

RESULTS: The expression of L-FABP and PPAR-α mRNAs in control rats showed no obvious changes. No steatosis was observed at week 2 in rats fed a high-fat diet. The expression of L-FABP mRNA increased obviously in rats fed a high-fat diet at week 4 (0.59 ± 0.06 vs 0.52 ± 0.03, P < 0.05), reaching the peak at weeks 8 and 12 (0.91 ± 0.07 and 0.92 ± 0.08 vs 0.52 ± 0.03, respectively; both P < 0.01). At week 18, the expression level of L-FABP mRNA declined significantly (0.59 ± 0.04 vs 0.92 ± 0.08, P < 0.01) but was still higher than that in the control group (P < 0.05). The expression of PPAR-α mRNA decreased obviously in rats fed a high-fat diet at week 4 (1.05 ± 0.09 vs 1.13 ± 0.07, P < 0.05), reaching the lowest level at weeks 8 and 12 (0.89 ± 0.04 and 0.85 ± 0.07 vs 1.13 ± 0.07, respectively; both P < 0.01). At week 18, the expression level of PPAR-α mRNA was elevated obviously (1.04 ± 0.07 vs 0.85 ± 0.07, P < 0.01) but was still lower than that in the control group. Steatosis become worst at week 12 but was improved greatly at week 18.

CONCLUSION: In the progression of rat NAFLD, PPAR-α mRNA expression decreases and L-FABP mRNA expression increases as steatosis becomes worse. Steatosis can be improved through diet.

Risk factors for type 2 diabetes accompanying nonalcoholic fatty liver: an analysis of 58 cases

AIM: To study the risk factors for type 2 diabetes mellitus (DM) accompanying nonalcoholic fatty liver and its relation with metabolic syndrome.

METHODS: Fifty-eight patients with type 2 DM were divided into type 2 DM accompanying nonalcoholic fatty liver group (group A) and simple type 2 DM group (group B). Body mass index (BMI), systolic blood pressure(SBP), diastolic blood pressure (DBP), glycosylated hemoglobin (HBA1C), total cholesterol (TC), triglyceride (TG), low density lipoprotein (LDP), alanine aminotransferase (ALT), and gamma- glutamyltransferase (GGT) were detected in two groups.

RESULTS: The BMI, SBP, DBP,HBA1C, TC, TG, LDL, ALT, AST and GGT were 25.2 kg/m² ± 3.2 kg/m², 133 mmHg ± 17 mmHg, 82 mmHg ± 10 mmHg, 5.5% ± 1.2%, 2.7 mmol/L ± 1.2 mmol/L, 1.2 mmol/L ± 1.2 mmol/L, 33 mmol/L ± 14 mmol/L, and 33 U/L ± 23 U/L, and 33 U/L ± 23 U/L, respectively, in group A, which were higher than those (21.2 kg/m² ± 3.3 kg/m², 132 mmHg ± 20 mmHg, 78 mmHg ± 8 mmHg, 8.5% ± 2.4%, 4.3 mmol/L ± 1.21 mmol/L, 1.2 mmol/L ± 1.1 mmol/L, 1.1 mmol/L ± 1.3 mmol/L, 16 U/L ± 12 U/L, and 15 U/L ± 12 U/L) in group B (P < 0.01).

CONCLUSION: Obesity, hypertension and hyperlipemia are the risk factors for type 2 DM accompanying nonalcoholic fatty liver.

Nonalcoholic fatty liver disease after liver transplantation for cryptogenic cirrhosis or nonalcoholic fatty liver disease

Nonalcoholic steatohepatitis (NASH) may account for many cases of cryptogenic cirrhosis. If so, then steatosis might recur after liver transplantation. Two thousand fifty-two patients underwent primary liver transplantation for chronic liver disease between 1986 and 2004. Serial liver biopsy samples were assessed for steatosis and fibrosis. Two hundred fifty-seven patients (12%) had a pretransplant diagnosis of cryptogenic cirrhosis (239) or NASH (18). Fatty liver developed in 31% and was more common when the pretransplant diagnosis was NASH (45% at 5 years versus 23% for cryptogenic cirrhosis, P = 0.007). NASH developed in only 4% and occurred exclusively when steatosis had already occurred. Steatosis after liver transplantation was associated with the baseline body weight and body mass index by univariate analyses, but no pretransplant or posttransplant characteristic independently predicted steatosis after liver transplantation because obesity was so common in all groups. Five percent and 10% developed bridging fibrosis or cirrhosis after 5 and 10 years, respectively, and this was more common after NASH (31%) than in those who developed steatosis alone (6%) or had no fat (3%, P = 0.002). One-, 5-, and 10-year survival was the same in patients who underwent transplantation for cryptogenic cirrhosis or NASH (86%, 71%, and 56%) and in patients who underwent transplantation for other indications (86%, 71%, and 53%; not significant), but death was more often due to cardiovascular disease and less likely from recurrent liver disease. In conclusion, fatty liver is common after liver transplantation for cryptogenic cirrhosis or NASH but is twice as common in the latter group; this suggests that some cryptogenic cirrhosis, but perhaps not all, is caused by NASH. Posttransplant NASH is unusual, and steatosis appears to be a prerequisite. Advanced fibrosis is uncommon, and survival is the same as that of patients who undergo transplantation for other causes.

Dietary lycopene and tomato extract supplementations inhibit nonalcoholic steatohepatitis-promoted hepatocarcinogenesis in rats

Epidemiological and experimental studies provide supportive evidence that lycopene (LY), a major carotenoid from tomatoes and tomato products, may act as a chemopreventive agent against certain types of cancers. We recently showed that high-fat diet (HFD)-induced nonalcoholic steatohepatitis (NASH) promoted diethylnitrosamine (DEN)-initiated hepatocarcinogenesis in a rat model. Using this model, we investigated the efficacy of an equivalent dosage of dietary LY from either a pure compound or a tomato extract (TE) against NASH-promoted hepatocarcinogenesis. Six groups of rats were injected with DEN and then fed either Lieber-DeCarli control diet or HFD with or without LY or TE for 6 weeks. Results showed that both LY and TE supplementations significantly decreased the number of altered hepatic foci expressing the placental form of glutathione S-transferase in the livers of HFD-fed rats. This was associated with significantly lower proliferating cell nuclear antigen positive hepatocytes and cyclinD1 protein, as well as decreased activation of extracellular signal-regulated kinase and nuclear NF-kappaB. Although both LY and TE supplementations reduced HFD-induced lipid peroxidation in the livers, we observed significantly decreased cytochrome P450 2E1, inflammatory foci and mRNA expression of proinflammatory cytokines (TNF-alpha, IL-1beta and IL-12) in the HFD+TE fed group but increased nuclear NF-E2-related factor-2 and heme oxygenase-1 proteins in the HFD+LY fed group, relative to HFD feeding alone. These data indicate that LY and TE can inhibit NASH-promoted hepatocarcinogenesis mainly as a result of reduced oxidative stress, which could be fulfilled through different mechanisms.

Abdominal magnetic resonance elastography

Magnetic resonance elastography (MRE) is a magnetic resonance imaging-based technique for quantitatively assessing the mechanical properties of tissues based on the propagation of shear waves. Multiple studies have described many potential applications of MRE, from characterizing tumors to detecting diffuse disease processes. Studies have shown that MRE can be successfully implemented to assess abdominal organs. The first clinical application of MRE to be well documented is the detection and characterization of hepatic fibrosis, which systematically increases the stiffness of liver tissue. In this diagnostic role, it offers a safer, less expensive, and potentially more accurate alternative to invasive liver biopsy. Emerging results suggest that measurements of liver and spleen stiffness may provide an indirect way to assess portal hypertension. Preliminary studies have demonstrated that it is possible to use MRE to evaluate the mechanical properties of other abdominal structures, such as the pancreas and kidneys. Steady technical progress in developing practical protocols for applying MRE in the abdomen and the pelvis provides opportunities to explore many other potential applications of this emerging technology.

Nonalcoholic steatohepatitis, animal models, and biomarkers: what is new?

Nonalcoholic fatty liver disease (NAFLD) is a clinicopathological term that encompasses a spectrum of abnormalities ranging from simple triglyceride accumulation in the hepatocytes (hepatic steatosis) to hepatic steatosis with inflammation (steatohepatitis, also known as nonalcoholic steatohepatitis or NASH). NASH can also progress to cirrhosis and hepatocellular carcinoma (HCC). Steatohepatitis has been estimated to affect around 5% of the total population and 20% of those who are overweight. The mechanisms leading to NASH and its progression to cirrhosis and HCC remain unclear, but it is a condition typically associated with obesity, insulin resistance, diabetes, and hypertriglyceridemia. This point corroborates the need for animal models and molecular markers that allow us to understand the mechanisms underlying this disease. Nowadays, there are numerous mice models to study abnormal liver function such as steatosis, NASH, and hepatocellular carcinoma. The study of the established animal models has provided many clues in the pathogenesis of steatosis and steatohepatitis, although these remain incompletely understood and no mice model completely fulfills the clinical features observed in humans. In addition, there is a lack of accurate sensitive diagnostic tests that do not involve invasive procedures. Current laboratory tests include some biochemical analysis, but their utility for diagnosing NASH is still poor. For that reason, a great effort is being made toward the identification and validation of novel biomarkers to assess NASH using high-throughput analysis based on genomics, proteomics, and metabolomics. The most recent discoveries and their validation will be discussed.

Age-related fat deposition in multifidus muscle could be a marker for nonalcoholic fatty liver disease

BACKGROUND

Although nonalcoholic fatty liver disease (NAFLD) is associated with visceral obesity, the relationship between visceral fat accumulation and skeletal muscle steatosis in patients with NAFLD has not been established. We evaluated: (1) the relationship between multifidus muscular tissue steatosis, visceral fat accumulation, and biochemical data in a cross-sectional study, and (2) the influence of weight reduction on multifidus muscular tissue steatosis in a longitudinal study.

METHODS

Three hundred thirty-three NAFLD patients were enrolled. Hepatic steatosis, visceral fat area, and the multifidus muscle/subcutaneous fat attenuation ratio (MM/F ratio) were evaluated by computed tomography. To evaluate how weight reduction produced by diet and exercise affected the MM/F ratio, changes in the MM/F ratio were compared between weight reduction and non-weight reduction groups.

RESULTS

There was a gender difference in MM/F ratios. The MM/F ratio was significantly correlated with age (male r = 0.613, P < 0.01; female r = 0.440, P < 0.01). The MM/F ratio was positively correlated with visceral fat area (male: r = 0.262, P < 0.01; female: r = 0.214, P < 0.01). A decrease in the MM/F ratio, concomitant with reduced visceral fat accumulation, led to alleviation of hepatic steatosis in 20 patients with weight reduction, but not in 22 patients without weight reduction.

CONCLUSIONS

The MM/F ratio was closely related to aging and visceral fat accumulation. The MM/F ratio was improved by weight reduction, indicating that fat accumulation in the multifidus muscle evaluated by computed tomography might be a therapeutic indicator of NAFLD.

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.

Efficacy of insulin-sensitizing agents in nonalcoholic fatty liver disease

AIM

To investigate the efficacy of insulin-sensitizing agents in nonalcoholic fatty liver disease (NAFLD) patients.

METHODS

This is an open-label, randomized, a single-center study. Sixty-four patients, with impaired glucose metabolism and elevated alanine aminotransferase for at least 6 months before enrollment and NAFLD activity score at least 5 in liver biopsy, were randomized as group 1 and received metformin 1700 mg/day, group 2 received rosiglitazone 4 mg/day, and group 3 received a combination of metformin 1700 mg/day and rosiglitazone 4 mg/day for 12 months.

RESULTS

Baseline demographic and laboratory findings were similar in all the three groups, except baseline insulin level that was significantly higher in group 1 and group 3 versus group 2 (P<0.05). Serum transaminase levels showed a significant decrease after treatment in both group 2 and group 3. Serum gamma-glutamyl transpeptidase levels decreased significantly only in the group 3. However, there was no significant change in liver tests of group 1. Postprandial glucose levels showed significant decrease in all of the three groups. Homeostasis model assessment-insulin resistance was reduced significantly in only group 2. NAFLD score was significantly decreased on follow-up biopsy of the patients in group 2 and group 3. Fibrosis did not change significantly after the treatment.

CONCLUSION

Rosiglitazone therapy seems to be more effective in metabolic control and histological improvement in NAFLD patients with impaired glucose metabolism.

Maternal high-fat feeding primes steatohepatitis in adult mice offspring, involving mitochondrial dysfunction and altered lipogenesis gene expression

Nonalcoholic fatty liver disease (NAFLD) describes an increasingly prevalent spectrum of liver disorders associated with obesity and metabolic syndrome. It is uncertain why steatosis occurs in some individuals, whereas nonalcoholic steatohepatitis (NASH) occurs in others. We have generated a novel mouse model to test our hypothesis: that maternal fat intake contributes to the development of NAFLD in adult offspring. Female mice were fed either a high-fat (HF) or control chow (C) diet before and during gestation and lactation. Resulting offspring were fed either a C or a HF diet after weaning, to generate four offspring groups; HF/HF, HF/C, C/HF, C/C. At 15 weeks of age, liver histology was normal in both the C/C and HF/C offspring. Kleiner scoring showed that although the C/HF offspring developed nonalcoholic fatty liver, the HF/HF offspring developed NASH. At 30 weeks, histological analysis and Kleiner scoring showed that both the HF/C and C/HF groups had NAFLD, whereas the HF/HF had a more severe form of NASH. Therefore, exposure to a HF diet in utero and during lactation contributes toward NAFLD progression. We investigated the mechanisms by which this developmental priming is mediated. At 15 weeks of age, hepatic mitochondrial electron transport chain (ETC) enzyme complex activity (I, II/III, and IV) was reduced in both groups of offspring from HF-fed mothers (HF/C and HF/HF). In addition, measurement of hepatic gene expression indicated that lipogenesis, oxidative stress, and inflammatory pathways were up-regulated in the 15-week-old HF/C and HF/HF offspring.

CONCLUSION

Maternal fat intake contributes toward the NAFLD progression in adult offspring, which is mediated through impaired hepatic mitochondrial metabolism and up-regulated hepatic lipogenesis.

Recurrent disease following liver transplantation for nonalcoholic steatohepatitis cirrhosis

Recurrence of the original disease following liver transplantation is not uncommon and can lead to graft failure. There are limited data on recurrent fatty liver disease following liver transplantation. The aim of this study was to determine the incidence of recurrent fatty liver disease in patients with biopsy-proven nonalcoholic steatohepatitis, its effect on survival, and whether there are any predictive factors for recurrence. We analyzed patients undergoing liver transplantation for nonalcoholic steatohepatitis cirrhosis from 1997 to 2008 at a single center. Patients undergoing transplantation for cholestatic disease, alcohol, hepatitis C, or cryptogenic cirrhosis were controls. Ninety-eight patients underwent transplantation for nonalcoholic steatohepatitis cirrhosis. Recurrent fatty liver disease was seen in 70%, 25% had recurrent nonalcoholic steatohepatitis, and 18% had stage II/IV or greater fibrosis at a mean of 18 months. No patients with recurrent nonalcoholic steatohepatitis developed graft failure or required retransplantation at a follow-up of 3 years. No recipient or donor factors were associated with disease recurrence, although patients with recurrent nonalcoholic steatohepatitis had a higher incidence of diabetes, weight gain, and dyslipidemia at the time of diagnosis of recurrence. One-third of patients with recurrent nonalcoholic steatohepatitis had normal liver enzymes at the time of diagnosis post-transplantation. In conclusion, recurrent fatty liver disease is common following liver transplantation for nonalcoholic steatohepatitis cirrhosis but does not lead to early allograft failure. Recurrent nonalcoholic steatohepatitis can occur despite normal liver enzymes, and features of metabolic syndrome are associated with disease recurrence.

Thrombotic risk factors and liver histologic lesions in non-alcoholic fatty liver disease

BACKGROUND/AIMS

The pathogenetic mechanisms of development of non-alcoholic steatohepatitis (NASH) and fibrosis are not clear, although thrombosis of small intrahepatic veins has been suggested to trigger liver tissue remodelling and thrombotic risk factors have been associated with more advanced fibrosis in chronic viral hepatitis (CVH). We evaluated the prevalence of thrombotic risk factors (RFs) in non-alcoholic fatty liver disease (NAFLD) and their possible association with fatty liver or NASH.

METHODS

We included 60 patients with histologically documented NAFLD and a historical cohort of 90 patients with chronic hepatitis B (n=39) or C (n=51). Thrombophilic factors were evaluated on the day of the liver biopsy.

RESULTS

One or more thrombotic RFs were detected in 37% of NAFLD patients, and >or= 2 RFs were detected in 12% of NAFLD patients, being less frequently present than in CVH patients (37% and 68%, respectively; P <or= 0.001). Among NAFLD cases, one or more thrombotic RFs were significantly more frequently present in NASH than simple fatty liver (56% vs. 8%; odds ratio [OR]: 13.8, 2.8-67.4, P<0.001). In multivariate analysis, NASH was independently associated with moderate to severe steatosis (adjusted OR: 24.3; P=0.001) and the presence of one or more thrombotic RFs (adjusted OR: 38.7; P=0.002). Fibrosis stage was worse in NASH patients with than without thrombotic RFs (2.5+/-1.1 vs. 1.3+/-1.1; P=0.002).

CONCLUSIONS

Thrombotic RFs are frequently present in patients with NAFLD and are associated with NASH and more advanced fibrosis. Such an association may have significant clinical implications, even though it is not clear yet whether it represents a primary or secondary phenomenon.

Science to practice: can MR elastography be used to detect early steatohepatitis in fatty liver disease?

SUMMARY

Fatty liver disease is common in Western countries. Some patients with this condition develop steatohepatitis, with ongoing liver injury that can lead to cirrhosis. Liver biopsy is currently required to differentiate between uncomplicated fatty liver disease and the more serious condition of steatohepatitis. Salameh and colleagues (1) studied the potential role of MR elastography for this diagnostic task in rat models of simple fatty liver and steatohepatitis. Their results suggest that MR elastography may have a potentially important role for noninvasive early detection of steatohepatitis in patients with fatty liver disease.

Systematic review of risk factors for fibrosis progression in non-alcoholic steatohepatitis

BACKGROUND/AIMS

Non-alcoholic steatohepatitis (NASH) is a growing public health problem. Evaluation of risk factors for fibrosis in NASH will help to target resources to reduce development of cirrhosis. This study had two aims; the first to compile longitudinal histological data to characterize the natural history of fibrosis progression in NASH, and second, to identify predictive factors for progression to advanced fibrosis (stage 3 or greater) in NASH.

METHODS

Subjects had to have a histological diagnosis compatible with NASH on their initial biopsy, received no intervention of proven histological benefit, and undergone two liver biopsies with at least an interval of one year between them.

RESULTS

Ten studies were selected comprising 221 patients. 37.6% had progressive fibrosis over a mean follow-up interval of 5.3 years (SD, 4.2 years, median, 3.7 years, range 1.0-21.3 years). Proportional hazards regression analysis demonstrated that age (HR=0.98, p=0.009) and inflammation on initial biopsy (any inflammation, HR=2.5, p=0.001; grade 1, HR=2.5, p=0.001; grade 2, HR=2.4, p=0.003) are independent predictors of progression to advanced fibrosis. Other traditional parameters (e.g. obesity, diabetes, hypertension) were not statistically significant predictors.

CONCLUSIONS

Presence of inflammation on the initial biopsy and age are independent predictors of progression to advanced fibrosis in patients with NASH.

Liver transplantation in patients with nonalcoholic steatohepatitis-related hepatocellular carcinoma

BACKGROUND & AIMS

The increasing incidence of hepatocellular carcinoma in the United States is only partially accounted for by hepatitis C virus (HCV) infections. The prevalence of hepatocellular carcinoma in patients with nonalcoholic steatohepatitis (NASH) is not known; guidelines from the American Association for the Study of Liver Diseases do not recommend surveillance imaging. We sought to determine the prevalence of hepatocellular carcinoma among patients undergoing liver transplantation for NASH-related cirrhosis and their outcome after surgery, compared with controls.

METHODS

We reviewed the records of adult patients with NASH cirrhosis who underwent liver transplantation by using a prospectively collected database from a single center. Data from patients with NASH cirrhosis were compared with matched controls who received transplantation for primary biliary cirrhosis/primary sclerosing cholangitis, alcoholic liver disease, or HCV.

RESULTS

Seventeen of 98 patients (17%) with NASH cirrhosis were diagnosed with hepatocellular carcinoma. The mean age was 63 years, and 70% were male. Six patients were diagnosed with hepatocellular carcinoma incidentally on explant. Survival after liver transplantation was 88% after mean follow-up of 2.5 years. The number of NASH patients known to have hepatocellular carcinoma before liver transplantation was greater than the number of patients with primary biliary cirrhosis/primary sclerosing cholangitis and comparable to the number of patients with alcoholic liver disease and HCV.

CONCLUSIONS

Patients with NASH cirrhosis are at risk for developing hepatocellular carcinoma; patients with NASH cirrhosis, especially men older than 50 years, should undergo surveillance imaging. Patients with NASH and hepatocellular carcinoma have good outcomes after liver transplantation.

Diagnosis and epidemiology of cirrhosis

Cirrhosis is defined histologically as an advanced form of progressive hepatic fibrosis with distortion of the hepatic architecture and regenerative nodule formation. It may be due to a variety of causes. It can be diagnosed incidentally on liver biopsy or hepatic imaging studies, or patients may present clinically with one or more features of hepatic failure. This article gives the reader a broad overview of the epidemiology, diagnosis, and natural history of cirrhosis; laying the foundation for subsequent articles, which will discuss the diagnosis and management of each of the specific cirrhosis-related complications.

A common variant in PNPLA3, which encodes adiponutrin, is associated with liver fat content in humans

AIMS/HYPOTHESIS

It has recently been suggested that the rs738409 G allele in PNPLA3, which encodes adiponutrin, is strongly associated with increased liver fat content in three different ethnic groups. The aims of the present study were as follows: (1) to try to replicate these findings in European individuals with quantitative measures of hepatic fat content; (2) to study whether the polymorphism influences hepatic and adipose tissue insulin sensitivity; and (3) to investigate whether PNPLA3 expression is altered in the human fatty liver.

METHODS

We genotyped 291 Finnish individuals in whom liver fat had been measured using proton magnetic resonance spectroscopy. Hepatic PNPLA3 expression was measured in 32 participants. Hepatic and adipose tissue insulin sensitivities were measured using a euglycaemic-hyperinsulinaemic (insulin infusion 0.3 mU kg(-1) min(-1)) clamp technique combined with infusion of [3-(3)H]glucose in 109 participants.

RESULTS

The rs738409 G allele in PNPLA3 was associated with increased quantitative measures of liver fat content (p = 0.011) and serum aspartate aminotransferase concentrations (p = 0.002) independently of age, sex and BMI. Fasting serum insulin and hepatic and adipose tissue insulin sensitivity were related to liver fat content independently of genotype status. PNPLA3 mRNA expression in the liver was positively related to obesity (r = 0.62, p < 0.0001) and to liver fat content (r = 0.58, p = 0.025) in participants who were not morbidly obese (BMI < 40 kg/m(2)).

CONCLUSIONS/INTERPRETATION

A common variant in PNPLA3 increases the risk of hepatic steatosis in humans.

Metabolic disturbances in non-alcoholic fatty liver disease

NAFLD (non-alcoholic fatty liver disease) refers to a wide spectrum of liver damage, ranging from simple steatosis to NASH (non-alcoholic steatohepatitis), advanced fibrosis and cirrhosis. NAFLD is strongly associated with insulin resistance and is defined by accumulation of liver fat >5% per liver weight in the presence of <10 g of daily alcohol consumption. The exact prevalence of NAFLD is uncertain because of the absence of simple non-invasive diagnostic tests to facilitate an estimate of prevalence. In certain subgroups of patients, such as those with Type 2 diabetes, the prevalence of NAFLD, defined by ultrasound, may be as high as 70%. NASH is an important subgroup within the spectrum of NAFLD that progresses over time with worsening fibrosis and cirrhosis, and is associated with increased risk for cardiovascular disease. It is, therefore, important to understand the pathogenesis of NASH and, in particular, to develop strategies for interventions to treat this condition. Currently, the 'gold standard' for the diagnosis of NASH is liver biopsy, and the need to undertake a biopsy has impeded research in subjects in this field. Limited results suggest that the prevalence of NASH could be as high as 11% in the general population, suggesting there is a worsening future public health problem in this field of medicine. With a burgeoning epidemic of diabetes in an aging population, it is likely that the prevalence of NASH will continue to increase over time as both factors are important risk factors for liver fibrosis. The purpose of this review is to: (i) briefly discuss the epidemiology of NAFLD to describe the magnitude of the future potential public health problem; and (ii) to discuss extra- and intra-hepatic mechanisms contributing to the pathogenesis of NAFLD, a better understanding of which may help in the development of novel treatments for this condition.

Differential expression of lumican and fatty acid binding protein-1: new insights into the histologic spectrum of nonalcoholic fatty liver disease

The basis of hepatocellular injury and progressive fibrosis in a subset of patients with nonalcoholic fatty liver disease (NAFLD) is poorly understood. We sought to identify hepatic proteins that are differentially abundant across the histologic spectrum of NAFLD. Hepatic protein abundance was measured in liver samples from four groups (n = 10 each) of obese (body mass index >30 kg/m(2)) patients: (1) obese normal group (normal liver histology), (2) simple steatosis (SS), (3) nonalcoholic steatohepatitis (NASH)-mild (steatohepatitis with fibrosis stage 0-1), and (4) NASH-progressive (steatohepatitis with fibrosis stage 2-4). Hepatic peptides were analyzed on an API Qstar XL quadrupole time-of-flight mass spectrometer using Analyst QS software. Linear trends tests were performed and used to screen for differential abundance. Nine known proteins were expressed with differential abundance between study groups. For seven proteins differential abundance is likely to have been on the basis increased hepatic lipid content and/or inflammation. Lumican, a 40-kDa keratin sulfate proteoglycan that regulates collagen fibril assembly and activates transforming growth factor-beta and smooth muscle actin, was expressed similarly in obese normal and SS but was overexpressed in a progressive manner in NASH-mild versus SS (124%, P < 0.001), NASH-progressive versus NASH-mild (156%, P < 0.001) and NASH-progressive versus obese normal (178%, P < 0.001). Fatty acid binding protein-1 (FABP-1), which is protective against the detergent effects of excess free fatty acids, facilitates intracellular free fatty acid transport and is an important ligand for peroxisome proliferator-activated receptor-mediated transcription, was overexpressed in SS when compared to the obese normal group (128%, P < 0.001), but was paradoxically underexpressed in NASH-mild versus SS (73%, P < 0.001), NASH-progressive versus NASH-mild (81%, P < 0.001), and NASH-progressive versus obese normal (59%, P < 0.001).

CONCLUSION

Histologically progressive NAFLD is associated with overexpression of lumican, an important mediator of fibrosis in nonhepatic tissues, whereas FABP-1 is paradoxically underexpressed in NASH, suggesting a new potential mechanism of lipotoxicity in NAFLD. Further studies are needed to determine the biologic basis of lumican and/or FABP-1 dysregulation in NAFLD.

Outcome after liver transplantation for NASH cirrhosis

Nonalcoholic steatohepatitis (NASH) associated cirrhosis is an increasing indication for liver transplant (LT). The aim of this study was to determine outcome and poor predictive factors after LT for NASH cirrhosis. We analyzed patients undergoing LT from 1997 to 2008 at a single center. NASH was diagnosed on histopathology. LT recipients with hepatitis C, alcoholic or cholestatic liver disease and cryptogenic cirrhosis acted as matched controls. Ninety-eight LT recipients were identified with NASH cirrhosis. Compared to controls, NASH patients had a higher BMI (mean 32.3 kg/m2), and were more likely to be diabetic and hypertensive. Mortality after transplant was similar between NASH patients and controls but there was a tendency for higher earlier mortality in NASH patients (30-day mortality 6.1%, 1-year mortality 21.4%). Sepsis accounted for half of all deaths in NASH patients, significantly higher than controls. NASH patients > or =60 years, BMI > or =30 kg/m2 with diabetes and hypertension (HTN) had a 50% 1-year mortality. In conclusion, patients undergoing LT for NASH cirrhosis have a similar outcome to patients undergoing LT for other indications. The combination of older age, higher BMI, diabetes and HTN are associated with poor outcome after LT. Careful consideration is warranted before offering LT to these high-risk patients.

Clinical features and outcomes of cirrhosis due to non-alcoholic steatohepatitis compared with cirrhosis caused by chronic hepatitis C

BACKGROUND AND AIM

Ethnic differences in non-alcoholic steatohepatitis (NASH) are well-documented, but there has been no study on the prognosis of Japanese NASH patients with cirrhosis. Accordingly, we compared cirrhotic NASH with liver cirrhosis caused by chronic hepatitis C (LC-C) to clarify its clinical features and define the risk factors for death.

METHODS

A prospective evaluation of the outcomes of NASH patients with severe fibrosis was started in 1990. Data on age- and sex-matched patients with biopsy-proven LC-C were collected retrospectively and used as the control.

RESULTS

There were 68 patients with cirrhotic NASH and 69 with LC-C. The Child-Turcotte-Pugh (CTP) class was similar in these two groups. Although the outcome of the NASH group was better than that of the LC-C group, cirrhotic NASH followed a similar course to that of LC-C; that is, complications of cirrhosis developed, including hepatocellular carcinoma (HCC; the 5-year HCC rate was 11.3% for NASH and 30.5% for HCV) and death (the 5-year survival rates were 75.2% and 73.8%, respectively). HCC was the leading cause of death in both groups (NASH, 47%; HCV, 68%). The occurrence of HCC and the CTP class were significant risk factors for mortality in NASH patients according to a multivariate analysis (HCC: hazard ratio [HR] 7.96, 95% confidence interval [CI] 2.45-25.88, CTP class A: HR 0.17, 95% CI 0.06-0.50).

CONCLUSION

In conclusion, the present study confirmed that cirrhotic NASH has a similar course to LC-C. The occurrence of HCC was the strongest predictor of mortality in the NASH groups. These findings may be helpful when deciding on therapeutic interventions for NASH and also for the daily management of these patients.

Maternal high-fat diet triggers lipotoxicity in the fetal livers of nonhuman primates

Maternal obesity is thought to increase the offspring's risk of juvenile obesity and metabolic diseases; however, the mechanism(s) whereby excess maternal nutrition affects fetal development remain poorly understood. Here, we investigated in nonhuman primates the effect of chronic high-fat diet (HFD) on the development of fetal metabolic systems. We found that fetal offspring from both lean and obese mothers chronically consuming a HFD had a 3-fold increase in liver triglycerides (TGs). In addition, fetal offspring from HFD-fed mothers (O-HFD) showed increased evidence of hepatic oxidative stress early in the third trimester, consistent with the development of nonalcoholic fatty liver disease (NAFLD). O-HFD animals also exhibited elevated hepatic expression of gluconeogenic enzymes and transcription factors. Furthermore, fetal glycerol levels were 2-fold higher in O-HFD animals than in control fetal offspring and correlated with maternal levels. The increased fetal hepatic TG levels persisted at P180, concurrent with a 2-fold increase in percent body fat. Importantly, reversing the maternal HFD to a low-fat diet during a subsequent pregnancy improved fetal hepatic TG levels and partially normalized gluconeogenic enzyme expression, without changing maternal body weight. These results suggest that a developing fetus is highly vulnerable to excess lipids, independent of maternal diabetes and/or obesity, and that exposure to this may increase the risk of pediatric NAFLD.

Nonalcoholic fatty liver disease and nonalcoholic steatohepatitis: Selected practical issues in their evaluation and management

Nonalcoholic fatty liver disease (NAFLD) is among the most common causes of chronic liver disease in the western world. It is now recognized that these patients have myriad of important co-morbidities (e.g., diabetes, hypothyroidism and metabolic syndrome). The workup of patients with suspected NAFLD should consist of excluding competing etiologies and systemic evaluation of metabolic comorbidities. NAFLD is histologically categorized into steatosis and steatohepatitis, two states with fairly dichotomous natural history. While significant progress has been made in terms of noninvasively predicting advanced fibrosis, insufficient progress has been made in predicting steatohepatitis. Currently, liver biopsy remains the gold standard for the histological stratification of NAFLD. While sustained weight loss can be effective to treat NASH, it is often difficult to achieve. Foregut bariatric surgery can be quite effective in improving hepatic histology in selected patients without liver failure or significant portal hypertension. Thiazolidinediones have shown promise and the results from the ongoing, large multicenter study should become available soon. Large multicenter studies of CB, receptor anatagonists are also underway but their results will not be available for several years. Several recent studies have highlighted that cardiovascular disease is the single most important cause of morbidity and mortality in this patient population.

CONCLUSION

Health care providers should not only focus on liver disease but also concentrate on aggressively modifying and treating their cardiovascular risk factors.

Nonalcoholic steatohepatitis and hepatocellular carcinoma in galectin-3 knockout mice

AIM

Nonalcoholic fatty liver disease (NAFLD) represents a growing health concern due to its rapidly increasing prevalence worldwide. Nonalcoholic steatohepatitis (NASH) is a progressing form of NAFLD, and recently many studies have reported that it could eventually develop into hepatocellular carcinoma (HCC). We previously reported that 6-month-old male galectin-3 knockout (gal3(-/-)) mice developed clinicopathological features similar to those of NAFLD in humans. Our aim was to investigate the changes in liver histology in gal3(-/-) mice by long-term observation.

METHODS

We initially investigated three 15-month-old gal3(-/-) mice, of which two developed multiple liver nodules with dysplastic changes. Then, we histopathologically examined the liver specimens of the 15-, 20- and 25-month-old gal3(-/-) mice and attempted to evaluate the liver morphology by contrast enhanced computed tomography (CT) before sacrifice.

RESULTS

At the age of 15 months or later, gal3(-/-) mice developed liver nodules with varying degrees of architectural and nuclear atypia based on mild to moderate delicate zone 3 fibrosis. In addition, we successfully confirmed the presence of some of the liver nodules by CT. We report herein that gal3(-/-) mice develop dysplastic liver nodules and HCC.

CONCLUSIONS

We believe that it would be interesting to use this murine model to investigate liver carcinogenesis based on a natural history of NAFLD. Furthermore, CT scanning might be a useful tool for longitudinal evaluation of morphological changes in vivo.

Fibrosis in diabetes complications: pathogenic mechanisms and circulating and urinary markers

Diabetes mellitus is characterized by a lack of insulin causing elevated blood glucose, often with associated insulin resistance. Over time, especially in genetically susceptible individuals, such chronic hyperglycemia can cause tissue injury. One pathological response to tissue injury is the development of fibrosis, which involves predominant extracellular matrix (ECM) accumulation. The main factors that regulate ECM in diabetes are thought to be pro-sclerotic cytokines and protease/anti-protease systems. This review will examine the key markers and regulators of tissue fibrosis in diabetes and whether their levels in biological fluids may have clinical utility.

Clinical and pathologic risk factors for atherosclerosis in cirrhosis: a comparison between NASH-related cirrhosis and cirrhosis due to other aetiologies

BACKGROUND/AIMS

The precise prevalence of risk factors for atherosclerosis in NASH-related cirrhosis is unknown. The aims of this study were: (1) to compare the prevalence of major risk factors for atherosclerosis between subjects who underwent liver transplantation for NASH-related cirrhosis and those with cirrhosis of other aetiologies and (2) to compare pathologic changes of atherosclerosis within the explants hepatic hilar arteries between the groups.

METHODS

Sixty subjects with NASH-related cirrhosis and 60 subjects with cirrhosis of other aetiologies were reviewed retrospectively. Demographic and clinical characteristics related to atherosclerosis were analyzed and compared. The hepatic hilar arteries of the explanted livers were examined for pathologic changes.

RESULTS

The prevalence of all coronary artery disease (CAD) risk factors and the metabolic syndrome was significantly higher in NASH-related cirrhosis group compared to cirrhosis of other aetiologies. The proportion of patients with a diagnosis of CAD was also significantly higher in the NASH-related cirrhosis group (21.6% vs. 5%, p=0.005). Pathological examination of hilar arteries showed possible atherosclerotic changes in only 4 cases (3 NASH-related cirrhosis; 1 HCV).

CONCLUSIONS

Major risk factors for atherosclerosis are significantly more prevalent in subjects with NASH-related cirrhosis than in subjects with cirrhosis of other aetiologies and are predictive of an increased prevalence of CAD. This study suggests that NASH-related cirrhosis is not protective against atherosclerosis.

Angiotensin II-induced non-alcoholic fatty liver disease is mediated by oxidative stress in transgenic TG(mRen2)27(Ren2) rats

BACKGROUND/AIMS

Non-alcoholic fatty liver disease (NAFLD) is a common health problem and includes a spectrum of hepatic steatosis, steatohepatitis and fibrosis. The renin-angiotensin system (RAS) plays a vital role in blood pressure regulation and appears to promote hepatic fibrogenesis. We hypothesized that increased RAS activity causes NAFLD due to increased hepatic oxidative stress.

METHODS

We employed the transgenic TG(mRen2)27(Ren2) hypertensive rat, harboring the mouse renin gene with elevated tissue Angiotensin II (Ang II).

RESULTS

Compared with normotensive Sprague-Dawley (SD) control rats, Ren2 developed significant hepatic steatosis by 9 weeks of age that progressed to marked steatohepatitis and fibrosis by 12 weeks. These changes were associated with increased levels of hepatic reactive oxygen species (ROS) and lipid peroxidation. Accordingly, 9-week-old Ren2 rats were treated for 3 weeks with valsartan, an angiotensin type 1 receptor blocker, or tempol, a superoxide dismutase/catalase mimetic. Hepatic indices for oxidative stress, steatosis, inflammation and fibrosis were markedly attenuated by both valsartan and tempol treatment.

CONCLUSIONS

This study suggests that Ang II causes development and progression of NAFLD in the transgenic Ren2 rat model by increasing hepatic ROS. Our findings also support a potential role of RAS in prevention and treatment of NAFLD.

Waist circumference correlates with hepatic fat accumulation in male Japanese patients with non-alcoholic fatty liver disease, but not in females

BACKGROUND AND AIM

Abdominal obesity, a component of metabolic syndrome, is a major risk factor for non-alcoholic fatty liver disease (NAFLD). In recent worldwide definitions of metabolic syndrome, waist measurement has been proposed as a simple and useful estimate of abdominal obesity, taking into account gender differences in waist circumference. The present cross-sectional study investigated the correlation of hepatic fat accumulation and waist circumference in Japanese NAFLD patients to determine if there are gender differences in this relationship.

METHODS

Consecutive patients (n = 2111) who had at least one of two criteria for liver disease (alanine aminotransferase [ALT] level >30 IU/mL and aspartate aminotransferase [AST]/ALT ratio <1) underwent abdominal ultrasonography. Patients positive for hepatitis B virus, hepatitis C virus or autoimmune antibodies and whose alcohol intake was >20 g/day were excluded. Patients with NAFLD underwent abdominal computed tomography. Hepatic fat accumulation was estimated by liver/spleen attenuation ratio (L/S ratio) and visceral adipose accumulation was measured as visceral fat area (VFA) at the umbilical level.

RESULTS

Of the 221 NAFLD patients, 103 were females. In males, the relationship between L/S ratio and waist circumference was negative (r =-0.356, P < 0.01), and there was no correlation in the female group. The relationship between L/S ratio and VFA was negative in both groups (males: r = -0.269, P < 0.01; females: r = -0.319, P < 0.01). Subcutaneous fat area/total fat area ratio at the umbilical level was larger in females than in males (P < 0.01).

CONCLUSIONS

In NAFLD patients, waist measurement is more susceptible to gender differences than VFA.

Serum phenylalanine concentration as a marker of liver function in obese patients before and after bariatric surgery

BACKGROUND

Human obesity is associated with increased serum phenylalanine concentration, which is probably caused by liver dysfunction related to liver steatosis. This study examines whether improvements of liver function after bariatric surgery is associated with a decrease of serum phenylalanine concentration caused by an increase of phenylalanine metabolism.

METHOD

Serum phenylalanine and alanine aminotransferase (an independent predictor of liver steatosis) concentrations as well as several parameters related to obesity were measured in 16 obese patients (seven men and nine women) before and 6 months after vertical banded gastroplasty. Ten (six men and four women) lean, healthy subjects served as controls.

RESULTS

Obese patients before surgery had approximately twofold higher serum phenylalanine concentration than control subjects. The serum phenylalanine concentration decreased 6 months after bariatric surgery. Serum alanine aminotransferase (ALT) concentration was higher in obese patients before surgery, and decreased 6 months after bariatric surgery. Changes in serum phenylalanine concentration correlated positively with changes of ALT concentration (r = 0.75; p < 0.001). The body weight, BMI, HOMA-IR, serum triacylglycerol, LDL-cholesterol/HLD-cholesterol ratio, leptin, insulin, and glucose concentrations were higher in obese patients, and decreased 6 months after bariatric surgery. Serum HDL-cholesterol concentration was lower in obese patients before surgery than in control subjects and increased 6 months after surgery.

CONCLUSION

Results obtained indicate that bariatric surgery-induced weight loss had beneficial effects on several laboratory parameters including serum phenylalanine, ALT, lipid concentrations and insulin resistance. A strong positive correlation between serum phenylalanine and serum ALT concentrations suggests that deterioration of liver function in obese patients is contributing to a decrease in phenylalanine metabolism and consequently to the increase of serum phenylalanine concentration. One can suppose that serum phenylalanine concentration could be noninvasive marker of liver dysfunction associated with liver steatosis in obese patients.

Contribution of de novo fatty acid synthesis to hepatic steatosis and insulin resistance: lessons from genetically engineered mice

Nonalcoholic fatty liver disease (NAFLD) is associated with obesity, insulin resistance, and type 2 diabetes. NAFLD represents a large spectrum of diseases ranging from (i) fatty liver (hepatic steatosis); (ii) steatosis with inflammation and necrosis; and (iii) cirrhosis. Although the molecular mechanism leading to the development of hepatic steatosis in the pathogenesis of NAFLD is complex, recent animal models have shown that modulating important enzymes in fatty acid synthesis in liver may be key for the treatment of NAFLD. This review discusses recent advances in the field.

Should patients with type 2 diabetes and raised liver enzymes be referred for further evaluation of liver disease?

Raised liver enzymes are common in type 2 diabetes (T2DM) but often considered benign. Non-alcoholic fatty liver was the cause in 65% of cases but other causes included alcoholic liver disease and viral hepatitis. Cirrhosis was identified in 11 patients. There is a significant burden of advanced liver diseases from a variety of aetiologies in patients with T2DM.

The impact of obesity on long-term outcomes in liver transplant recipients-results of the NIDDK liver transplant database

The impact of obesity on outcomes following liver transplantation has been difficult to determine, in part due to the confounding effects of ascites on BMI. We evaluated the impact of pretransplant recipient obesity on outcomes following liver transplantation using the NIDDK Liver Transplantation Database. Pretransplant BMI, corrected for ascites, was categorized as underweight (BMI <18 kg/m(2)), normal weight (BMI 18-25 kg/m(2)), overweight (BMI 25.1-30 kg/m(2)), Class I obese (BMI 30.1-35 kg/m(2)), Class II obese (BMI 35.1-40 kg/m(2)) and Class III obese (BMI >40 kg/m(2)). Primary outcomes were patient and graft survival. Secondary outcomes included days in hospital and days in ICU. Data from 704 adult liver transplant recipients from the NIDDK LTD and a further 609 patients from the Mayo Clinic were analyzed. Early and late patient and graft survival was similar across all BMI categories. Correcting for ascites volume resulted in 11-20% of patients moving into a lower BMI classification. The relative risk for mortality increased by 7% for each liter of ascites removed. We conclude that corrected BMI is not independently predictive of patient or graft survival. Obesity, within the ranges observed in this study, should not be considered to be a contraindication to liver transplantation in the absence of other relative contraindications.

Weight loss, dietary advice and statin therapy in non-alcoholic fatty liver disease: a retrospective study

BACKGROUND

Studies have shown that weight loss can have a favourable effect upon non-alcoholic fatty liver disease (NAFLD). However, the most effective means of achieving weight loss and safety profile of lipid-lowering drugs in the presence of NAFLD is unknown.

AIM

To investigate the effect of dietary advice and lipid-lowering drugs, particularly statins, on patients with NAFLD and dyslipidaemia.

DESIGN

Observational records based study.

METHODS

We studied 71 patients with NAFLD and dyslipidaemia diagnosed and treated between 1996 and 2002 at University Hospital Lewisham. Some were referred to a dietician for weight loss advice as part of their management. After treatment all patients were assessed for changes in weight, serum alanine transaminase (ALT) and serum lipids including serum cholesterol, serum high density lipoprotein (HDL) and serum triglycerides.

RESULTS

Thirty-seven male and 34 female patients with NAFLD and dyslipidaemia were followed up for a mean period of 440 +/- 374 days (median 335). Regression analysis revealed a significant association between changes in weight and changes in serum ALT (p < 0.039). Dietary advice failed to reduce body weight but significantly lowered the serum cholesterol to HDL ratio (p = 0.05). Only 15.4% of patients taking statins experienced a rise in serum ALT > or = 40 U/l, and in each case the rise was transient, returning near baseline or below without discontinuation of statin treatment.

CONCLUSIONS

Weight loss appears to improve NAFLD, and dietary advice and lipid-lowering drugs may be beneficial for patients with NAFLD and dyslipidaemia even if weight loss is not achieved. Statins appear to be safe and efficacious in this group.

Low circulating levels of dehydroepiandrosterone in histologically advanced nonalcoholic fatty liver disease

The biological basis of variability in histological progression of nonalcoholic fatty liver disease (NAFLD) is unknown. Dehydroepiandrosterone (DHEA) is the most abundant steroid hormone and has been shown to influence sensitivity to oxidative stress, insulin sensitivity, and expression of peroxisome proliferator-activated receptor alpha and procollagen messenger RNA. Our aim was to determine whether more histologically advanced NAFLD is associated with low circulating levels of DHEA. Serum samples were obtained prospectively at the time of liver biopsy in 439 patients with NAFLD (78 in an initial and 361 in validation cohorts) and in controls with cholestatic liver disease (n = 44). NAFLD was characterized as mild [simple steatosis or nonalcoholic steatohepatitis (NASH) with fibrosis stage 0-2] or advanced (NASH with fibrosis stage 3-4). Serum levels of sulfated DHEA (DHEA-S) were measured by enzyme-linked immunosorbent assay. Patients with advanced NAFLD had lower plasma levels of DHEA-S than patients with mild NAFLD in both the initial (0.25 +/- 0.07 versus 1.1 +/- 0.09 microg/mL, P < 0.001) and validation cohorts (0.47 +/- 0.06 versus 0.99 +/- 0.04 microg/mL, P < 0.001). A "dose effect" of decreasing DHEA-S and incremental fibrosis stage was observed with a mean DHEA-S of 1.03 +/- 0.05, 0.96 +/- 0.07, 0.83 +/- 0.11, 0.66 +/- 0.11, and 0.35 +/- 0.06 microg/mL for fibrosis stages 0, 1, 2, 3, and 4, respectively. All patients in both cohorts in the advanced NAFLD group had low DHEA-S levels, with the majority in the hypoadrenal range. The association between DHEA-S and severity of NAFLD persisted after adjusting for age. A relationship between disease/fibrosis severity and DHEA-S levels was not seen in patients with cholestatic liver diseases.

CONCLUSION

More advanced NAFLD, as indicated by the presence of NASH with advanced fibrosis stage, is strongly associated with low circulating DHEA-S. These data provide novel evidence for relative DHEA-S deficiency in patients with histologically advanced NASH.

Fatty Liver

Although the epidemic of obesity has been accompanied by an increase in the prevalence of the metabolic syndrome, not all obese develop the syndrome and even lean individuals can be insulin resistant. Both lean and obese insulin resistant individuals have an excess of fat in the liver which is not attributable to alcohol or other known causes of liver disease, a condition defined as nonalcoholic fatty liver disease (NAFLD) by gastroenterologists. The fatty liver is insulin resistant. Liver fat is highly significantly and linearly correlated with all components of the metabolic syndrome independent of obesity. Overproduction of glucose, VLDL, CRP, and coagulation factors by the fatty liver could contribute to the excess risk of cardiovascular disease associated with the metabolic syndrome and NAFLD. Both of the latter conditions also increase the risk of type 2 diabetes and advanced liver disease. The reason why some deposit fat in the liver whereas others do not is poorly understood. Individuals with a fatty liver are more likely to have excess intraabdominal fat and inflammatory changes in adipose tissue. Intervention studies have shown that liver fat can be decreased by weight loss, PPARγ agonists, and insulin therapy.

Magnetic resonance imaging of hepatic fibrosis: emerging clinical applications

Chronic liver disease and cirrhosis remains a major public health problem worldwide. While the majority of complications from chronic liver disease result from progressive hepatic fibrosis, the available diagnostic tests used in clinical practice are not sensitive or specific enough to detect occult liver injury at early or intermediate stages. While liver biopsy can stage the extent of fibrosis at diagnosis, its utility as a tool for longitudinal monitoring will be limited at the population level. To date, a number of methods including serum marker panels and ultrasound-based transient elastrography have been proposed for the non-invasive identification of hepatic fibrosis. Novel techniques including magnetic resonance (MR) spectroscopy, diffusion weighted MR, and MR elastography have also emerged for detecting fibrosis. In contrast to other non-invasive methods, MR imaging holds the promise of providing functional and biological information about hepatic pathophysiology as it relates to the natural history and future treatment of hepatic fibrosis. (HEPATOLOGY 2007.).

ChREBP, a transcriptional regulator of glucose and lipid metabolism

Dysregulations in hepatic lipid synthesis are often associated with obesity and type 2 diabetes, and therefore a perfect understanding of the regulation of this metabolic pathway appears essential to identify potential therapeutic targets. Recently, the transcription factor ChREBP (carbohydrate-responsive element-binding protein) has emerged as a major mediator of glucose action on lipogenic gene expression and as a key determinant of lipid synthesis in vivo. Indeed, liver-specific inhibition of ChREBP improves hepatic steatosis and insulin resistance in obese ob/ob mice. Since ChREBP cellular localization is a determinant of its functional activity, a better knowledge of the mechanisms involved in regulating its nucleo-cytoplasmic shuttling and/or its post-translational activation is crucial in both physiology and physiopathology. Here, we review some of the studies that have begun to elucidate the regulation and function of this key transcription factor in liver.

Ultrasound-based transient elastography for the detection of hepatic fibrosis: systematic review and meta-analysis

BACKGROUND & AIMS

Ultrasound-based transient elastography is a promising noninvasive alternative to liver biopsy for detecting hepatic fibrosis. However, its overall test performance in various settings remains unknown. The aims of this study were to perform a systematic review and meta-analysis of diagnostic accuracy studies comparing ultrasound-based transient elastography with liver biopsy for hepatic fibrosis.

METHODS

Electronic and manual bibliographic searches to identify potential studies were performed. Selection of studies was based on reported accuracy of ultrasound-based transient elastography compared with liver biopsy. Data extraction was performed independently by 2 reviewers. Meta-analysis combined the sensitivities, specificities, and likelihood ratios of individual studies. Extent and reasons for heterogeneity were assessed.

RESULTS

Nine studies in full publication were identified. For patients with stage IV fibrosis (cirrhosis), the pooled estimates for sensitivity were 87% (95% confidence interval [CI], 84%-90%), specificity 91% (95% CI, 89%-92%), positive likelihood ratio 11.7 (95% CI, 7.9-17.1), and negative likelihood ratio 0.14 (95% CI, 0.10-0.20). Among 7 investigations reporting patients with stages II-IV fibrosis, the pooled estimates for sensitivity were 70% (95% CI, 67%-73%), specificity 84% (95% CI, 80%-88%), positive likelihood ratio 4.2 (95% CI, 2.4-7.2), and negative likelihood ratio 0.31 (95% CI, 0.23-0.43). Diagnostic threshold (or cut-off value) bias was identified as an important cause of heterogeneity for pooled results in both patient groups.

CONCLUSIONS

Ultrasound-based transient elastography appears to be a clinically useful test for detecting cirrhosis.

Assessment of hepatic fibrosis with magnetic resonance elastography

BACKGROUND & AIMS

Accurate detection of hepatic fibrosis is crucial for assessing prognosis and candidacy for treatment in patients with chronic liver disease. Magnetic resonance (MR) elastography, a technique for quantitatively assessing the mechanical properties of soft tissues, has been shown previously to have potential for noninvasively detecting liver fibrosis. The goal of this work was to obtain preliminary estimates of the sensitivity and specificity of the technique in diagnosing liver fibrosis, and to assess its potential for identifying patients who potentially can avoid a biopsy procedure.

METHODS

MR elastography was performed in 35 normal volunteers and 50 patients with chronic liver disease. MR imaging measurements of hepatic fat to water ratios were obtained to assess the potential for fat infiltration to affect stiffness-based detection of fibrosis.

RESULTS

Liver stiffness increased systematically with fibrosis stage. Receiver operating curve analysis showed that, with a shear stiffness cut-off value of 2.93 kilopascals, the predicted sensitivity and specificity for detecting all grades of liver fibrosis is 98% and 99%, respectively. Receiver operating curve analysis also provided evidence that MR elastography can discriminate between patients with moderate and severe fibrosis (grades 2-4) and those with mild fibrosis (sensitivity, 86%; specificity, 85%). Hepatic stiffness does not appear to be influenced by the degree of steatosis.

CONCLUSIONS

MR elastography is a safe, noninvasive technique with excellent diagnostic accuracy for assessing hepatic fibrosis. Based on the high negative predictive value of MR elastography, an initial clinical application may be to triage patients who are under consideration for biopsy examination to assess possible hepatic fibrosis.

Role of ChREBP in hepatic steatosis and insulin resistance

Non-alcoholic fatty liver disease is tightly associated with insulin resistance, type 2 diabetes and obesity, but the molecular links between hepatic fat accumulation and insulin resistance are not fully identified. Excessive accumulation of triglycerides (TG) is one the main characteristics of non-alcoholic fatty liver disease and fatty acids utilized for the synthesis of TG in liver are available from the plasma non-esterified fatty acid pool but also from fatty acids newly synthesized through hepatic de novo lipogenesis. Recently, the transcription factor ChREBP (carbohydrate responsive element binding protein) has emerged as a central determinant of lipid synthesis in liver through its transcriptional control of key genes of the lipogenic pathway, including fatty acid synthase and acetyl CoA carboxylase. In this mini-review, we will focus on the importance of ChREBP in the physiopathology of hepatic steatosis and insulin resistance by discussing the physiological and metabolic consequences of ChREBP knockdown in liver of ob/ob mice.