Macaca radiata (bonnet monkey): a spontaneous model of nonalcoholic fatty liver disease

Background: Nonalcoholic fatty liver disease (NAFLD) is a well‐recognized condition that includes a spectrum of clinicopathology conditions ranging from steatotosis to cirrhosis and liver failure. Available animal models are not ideal as they show only a partial resemblance to characteristic human NAFLD. Objective: This study was aimed at identifying a nonhuman primate model of NAFLD resembling features of human NAFLD, which will be useful in understanding the mechanism of the onset of this disease and for developing novel therapeutic modalities. Methods: The histological status of the liver and serum levels of triglycerides (TG), cholesterol, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) of aged bonnet monkeys were compared with that of the aged rhesus and adult bonnet monkeys. Histopathology and immunostaining of liver sections and oil red ‘O’ confirmed NAFLD in aged bonnet monkeys. Results: Aged bonnet monkeys showed a significant (P<0.01) increase in serum TG, AST and ALT compared with aged rhesus and adult bonnet monkeys. Histopathology of the liver of aged bonnet macaques showed diffused microvesicular and macrovesicular fatty changes, perivenular and portal and perisinusoidal fibrosis with fatty degeneration of hepatocytes, and immunostaining of liver sections was suggestive of NAFLD. Conclusion: The spontaneous occurrence of NAFLD in normal animals is rare, but aged bonnet monkeys may serve as a unique animal model for studies related to NAFLD because they mimic pathophysiological features of human NAFLD.     

Short-term orlistat therapy improves fatty infiltration indices and liver fibrosis scores in patients with non-alcoholic fatty liver disease and metabolic syndrome

Background and study aimsPatients with non-alcoholic fatty liver disease (NAFLD) exhibit features of metabolic syndrome, including a high body mass index, central obesity, high blood pressure, and abnormal lipid profile values. Orlistat, an intestinal lipase enzyme inhibitor, improves insulin resistance. We aimed to investigate the effects of short-term therapy with orlistat on the components of metabolic syndrome associated with NAFLD and explore its effect on liver fibrosis scores.Patients and methodsAn open-label placebo-controlled clinical study using orlistat for 12 weeks was carried out on 50 patients with NAFLD. They were divided into a placebo group (Group I) and an orlistat treatment group (120 mg per day, Group II). The diagnosis of NAFLD was made by ultrasonography and laboratory investigations. Anthropometric and blood pressure measurements and hepatic liver enzymes, fasting lipids, and blood glucose levels were determined before and after treatment. Lipid indices including cholesterol (Chol-I), triglyceride (TG-I), triglyceride-glucose (TYG-I), and the scores for lipid fibrosis using the NAFLD fibrosis score (NFS) and Fibrosis-4 score (Fib-4) were also determined.ResultsOrlistat significantly improved the anthropometric and metabolic indices (TG-I, TYG-I) and liver enzymes. Orlistat demonstrated a favorable impact on the NAS and Fib-4 scores for liver fibrosis.ConclusionOrlistat improves the components of metabolic syndrome, leading to the improvement of insulin resistance and thereby improves fatty infiltration of the liver. To a lesser extent, orlistat improved the liver fibrosis scores.     

Leptin, insulin resistance, and liver fibrosis in human nonalcoholic fatty liver disease

BACKGROUND/AIMS: Data from animal models of fibrosis and fatty liver suggest that leptin may mediate the profibrogenic responses in the liver, but the association of leptin and liver fibrosis in human nonalcoholic fatty liver disease (NAFLD) remains undefined. We aimed at determining the relation between leptin and liver fibrosis in human NAFLD. METHODS: Human plasma leptin and several indicators of insulin resistance were measured in 88 NAFLD patients and matched controls. RESULTS: Leptin levels were significantly greater in patients with more advanced fibrosis (P = 0.005). By multivariate analysis, the significant association between leptin and fibrosis was abolished (adjusted P = 0.3) when controlling for confounders including age, gender, BMI, diabetes and insulin resistance. Only age (adjusted P = 0.006) and insulin sensitivity (adjusted P = 0.04) correlated significantly with fibrosis stage. A second liver biopsy was performed in 39 out of the 88 patients at 27.9 +/- 16 months. Leptin levels were not significantly different between patients who had fibrosis progression (n = 10) and those who did not (n = 29). CONCLUSIONS: In human NAFLD, no relationship between leptin levels and fibrosis stage was demonstrated. The correlation of leptin and fibrosis severity seems to be an indicator of the factors that determine leptin production.     

Nonalcoholic fatty liver disease in severely obese subjects

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) has been consistently associated with obesity and insulin resistance. Nonalcoholic steatohepatitis (NASH) is a histological entity within NAFLD that can progress to cirrhosis. The exact prevalence of NASH in severe obesity is unknown. It is unclear whether differences in insulin sensitivity exist among subjects with NASH and simple fatty liver. OBJECTIVE: To evaluate the prevalence and correlates of NASH and liver fibrosis in a racially diverse cohort of severely obese subjects. DESIGN: Ninety-seven subjects were enrolled. Liver biopsies, indirect markers of insulin resistance, metabolic parameters, and liver function tests were obtained. RESULTS: Thirty-six percent of subjects had NASH and 25% had fibrosis. No cirrhosis was diagnosed on histology. Markers of hyperglycemia, insulin resistance, and the metabolic syndrome but not body mass index were associated with the presence of NASH and fibrosis. Elevated transaminase levels correlated strongly with NASH and fibrosis but 46% subjects with NASH had normal transaminases. Subjects with NASH had more severe insulin resistance when compared to those with simple fatty liver. A signal detection model incorporating AST and the presence of diabetes predicted the presence of NASH while another incorporating ALT and HbA1C predicted the presence of fibrosis. CONCLUSIONS: NAFLD is associated with the metabolic syndrome rather than excess adipose tissue in severe obesity. Insulin resistance is higher in subjects with NASH versus those with simple fatty liver. Statistical models incorporating markers of liver injury and hyperglycemia may be useful in predicting the presence of liver pathology in this population.     

Nonalcoholic fatty liver disease/steatohepatitis: epidemiology, pathogenesis, clinical presentation and treatment

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic hepatic disorder in Western countries, with a prevalence of 20-30%. NAFLD comprises 'silent liver disease', in which simple steatosis is the only histological finding and which is benign in course, and nonalcoholic steatohepatitis, which is characterized by hepatocellular injury and inflammation with or without fibrosis. NAFLD is clinically important, because even benign fatty liver can progress to steatohepatitis in many patients, which can lead to liver cirrhosis and its complications and hepatocellular carcinoma. NAFLD is a hepatic manifestation of metabolic syndrome; it is closely related to other clinical features of metabolic syndrome, and thus to cardiovascular morbidity. There are several different noninvasive techniques for formal diagnosis and follow-up, but liver biopsy remains the gold standard. The most important therapeutic strategies include lifestyle changes, including changes in dietary habits aimed at weight loss and blood pressure regulation, with a consequent decrease in insulin resistance. For some patients with NAFLD/nonalcoholic steatohepatitis, pharmacological treatment is the best option, although further studies are needed to confirm its efficacy and tolerability.     

Nonalcoholic Fatty Liver Disease Treated by Gastroplasty

Nonalcoholic steatohepatitis (NASH), which is the most severe histologic form of nonalcoholic fatty liver disease (NAFLD), is emerging as the most common clinically important form of liver disease in obese patients. The prevalence of NASH may increase with the rise in the rate of obesity and metabolic syndrome in affluent communities. The aim of this work is to describe clinical and histopathologic findings and correlate liver tissue damage to the length of duration of the obesity in the group of patients who underwent surgery as obesity treatment. Eighty-seven severely or morbidly obese patients underwent gastroplasty. Each patient was evaluated with complete clinical and laboratory medical assessment together with wedge liver biopsy taken from 59 unselected patients during the surgery. Patients were followed up for 41 months. Repeat liver biopsy was taken from 10 patients. Pathologic analysis recorded the presence and degree of steatosis, portal and lobular inflammation and fibrosis. Age, body mass index (BMI), and laboratory assessment correlated with pathologic data. Male patients showed more pronounced metabolic syndrome and fatty liver damage. Patients who become obese in childhood or as teenagers showed no differences in metabolic syndrome and NAFLD in mature age. There was statistically significant association between BMA, elevated transaminases, NAFLD, and fibrosis. Significant weight reduction was observed within first year after surgery, was slower in the second year, and stabilized within third year. Remarkable improvement followed in biological markers of metabolic syndrome. Ninety-six percent of initial liver biopsies had steatosis; 16% developed steatohepatitis and mild perivenular fibrosis. Significant improvement of the degenerative and inflammatory hepatic lesions in repeated biopsies and liver function readings was noted within 8 months after surgery. Obesity is a major and independent risk factor for the metabolic syndrome, NAFLD, NASH, and fibrosis. Surgical treatment improves metabolic abnormalities and hepatic lesions in long-term observations.     

Relative contribution of iron burden, HFE mutations, and insulin resistance to fibrosis in nonalcoholic fatty liver

The mechanism(s) determining the progression from fatty liver to steatohepatitis is currently unknown. Our goal was to define the relative impact of iron overload, genetic mutations of HFE, and insulin resistance on the severity of liver fibrosis in a population of subjects with nonalcoholic fatty liver disease (NAFLD) who had low prevalence of obesity and no overt symptoms of diabetes. In a cohort of 263 prospectively enrolled patients with NAFLD, 7.4% of patients had signs of peripheral iron overload and 9% had signs of hepatic iron overload, but 21.1% had hyperferritinemia. The prevalence of C282Y and H63D HFE mutations was similar to the general population and mutations were not associated with iron overload. Although subjects were on average only moderately overweight, insulin sensitivity, measured both in the fasting state and in response to oral glucose, was lower. Univariate analysis demonstrated that the presence of severe fibrosis was independently associated with older age, female sex, overweight, aspartate/alanine aminotransferase ratio, serum ferritin level, fasting glucose and insulin levels, decreased insulin sensitivity, and with histologic features (degree of necroinflammation and steatosis). After adjustment for body mass index (BMI), age, sex, and degree of steatosis, ferritin levels (odds ratio [OR] = 1.77; 95% CI = 1.21- 2.58; P =.0032) and the oral glucose insulin sensitivity (OR = 0.53; CI = 0.33-0.87; P =.0113) were independent predictors of severe fibrosis. In conclusion, the current study indicates that insulin resistance is a major, independent risk factor for advanced fibrosis in patients with NAFLD. Increased ferritin levels are markers of severe histologic damage, but not of iron overload. Iron burden and HFE mutations do not contribute significantly to hepatic fibrosis in the majority of patients with NAFLD.     

The effect of etanercept on hepatic fibrosis risk in patients with non-alcoholic fatty liver disease, metabolic syndrome, and psoriasis

Background

Patients with psoriasis show a greater prevalence of non-alcoholic fatty liver disease (NAFLD) and metabolic syndrome than the general population. Moreover, patients with NAFLD and psoriasis are at higher risk of severe liver fibrosis than their counterparts with NAFLD and without psoriasis. The link between these three pathological conditions is a chronic low-grade inflammatory status. In this study, we aimed to evaluate the effect of etanercept versus psoralen and UVA (PUVA) therapy on the hepatic fibrosis risk in patients with psoriasis, metabolic syndrome, and NAFLD (with NAFLD diagnosed by ultrasonography).

Methods

Eighty-nine patients with chronic moderate-to-severe plaque-type psoriasis, metabolic syndrome, and NAFLD received etanercept or PUVA treatment. The two groups of patients were compared for anthropometric variables (body mass index and waist/hip ratio), lipid profile, glucose homeostasis, inflammatory status, risk of hepatic fibrosis, and ultrasonographic aspect of the liver, both at baseline (time [T] 0) and after 24 weeks of treatment (T24).

Results

After 24 weeks of treatment, only in the group receiving etanercept, we detected significant reductions (p < 0.05) in the aspartate transaminase (AST)/alanine transaminase (ALT) ratio, C-reactive protein (CRP) serum levels, fasting insulin levels, and homeostasis model assessment (HOMA) index, and a significant increase in the Quantitative Insulin-Sensitivity Check Index (QUICKI) (p < 0.05).

Conclusions

In patients with psoriasis, metabolic syndrome, and NAFLD, the risk of the development of hepatic fibrosis seems to be directly correlated with insulin resistance. Etanercept could be more efficacious to reduce the risk of developing hepatic fibrosis than PUVA therapy, and this preventive effect could be related to its anti-inflammatory and glucose homeostatic properties. We note that a limitation of the study was that the diagnosis of NAFLD was conducted by ultrasonography.     

Fibrosis in genotype 3 chronic hepatitis C and nonalcoholic fatty liver disease: Role of insulin resistance and hepatic steatosis

Hepatic steatosis has been associated with fibrosis, but it is unknown whether the latter is independent of the etiology of fat infiltration. We analyzed the relationship between clinical characteristics, insulin resistance (HOMA-R) and histological parameters in 132 patients with "viral" steatosis caused by genotype 3 chronic hepatitis C (CHC-3) and 132 patients with "metabolic" steatosis caused by nonalcoholic fatty liver disease (NAFLD), matched by age, BMI, and degree of liver fat accumulation. Tests of liver function were comparable in the two study populations. The prevalence of features of insulin resistance was higher in NAFLD, as was HOMA-R (P = .008). Logistic regression analysis confirmed that steatosis was associated with a high viral load and low serum cholesterol in CHC-3, and with high aminotransferase, glucose, ferritin and hypertriglyceridemia in NAFLD. At univariate analysis, advanced fibrosis was associated with steatosis in NAFLD, but not in CHC-3. Other parameters related to fibrosis severity were HOMA-R and a low platelet count in CHC-3, and high aminotransferases, HOMA-R, ferritin and low HDL-cholesterol in NAFLD. On multivariate analysis, only low platelet count (OR = 0.78; 95% CI, 0.67-0.92) and HOMA-R (OR = 2.98; 1.13-7.89) were independent predictors of advanced fibrosis in CHC-3. In NAFLD, severe fibrosis was predicted by fat grading (OR = 3.03; 1.41-6.53), ferritin (OR = 1.13; 1.03-1.25) and HOMA-R (OR = 1.16; 1.02-1.31). In conclusion, insulin resistance is an independent predictor of advanced fibrosis in both NAFLD and CHC-3, but the extent of steatosis contributes to advanced disease only in NAFLD. Virus-induced hepatic steatosis as seen in CHC-3 does not contribute significantly to liver fibrosis.     

Is there any link between dietary pattern and development of nonalcoholic fatty liver disease in adolescence? An expert review

Evaluation of: Oddy WH, Herbison CE, Jacoby P et al. The western dietary pattern is prospectively associated with nonalcoholic fatty liver disease in adolescence. Am. J. Gastroenterol. 108, 778–785 (2013).

The prevalence of overweight and obesity in childhood is a major public health concern. According to the obesity trend, the prevalence of pediatric nonalcoholic fatty liver disease (NAFLD) is also increasing. Nonalcoholic fatty liver disease is characterized by a spectrum of hepatic lesions (i.e., steatosis, ballooning, necroinflammation and fibrosis) that can progress to cirrhosis, hepatocellular carcinoma and liver failure with the consequent need for liver transplantation. Pediatric NAFLD is typically of primary origin and it is strongly associated with several features of the metabolic syndrome such as obesity, insulin resistance, dyslipidemia and Type 2 diabetes. The evaluated article reports the prospective relationship between dietary patterns at age 14 years and the presence of NAFLD at age 17 years. A total of 995 adolescents completed a food frequency questionnaire at 14 years and had liver ultrasound at 17 years. Prospective associations between the dietary pattern scores and the risk of NAFLD were analyzed using multiple logistic regression analyses. Nonalcoholic fatty liver disease was present in 15.2% of adolescents. A healthy dietary pattern at 14 years appeared protective against NAFLD at 17 years in centrally obese adolescents. On the contrary, a western dietary pattern at 14 years in this cohort was associated with an increased risk of NAFLD at 17 years, particularly in obese adolescents.