Nutritional modulation of nonalcoholic fatty liver disease and insulin resistance: human data

Perinatal exposure to environmental endocrine disruptor bisphenol A aggravates the onset of non-alcoholic fatty liver disease (NAFLD) in weanling F1 offspring of obese rats

Bisphenol A (BPA) is a major environmental pollutant and food contaminant with endocrine-disrupting effects on human and animal health. Perinatal and developmental exposure to BPA has been known to cause hepatotoxicity in adulthood. However, its intergenerational effects in a metabolically challenged population have been scarcely investigated. Our study was designed to assess the intergenerational effect of an environmentally relevant dose of BPA and diet-induced parental obesity on the hepatic health outcome of F1 offspring. Wistar rats were given a high-fat diet to induce obesity, followed by chronic low dosages of BPA (10 ppm × 180 days) in drinking water. Post-treatment, rats were crossed within groups to obtain the F1 generation. Weanling pups were observed for weight gain, levels of hepatic antioxidants, liver function enzymes, cholesterol, C-reactive protein, and triglyceride in the serum. Histological changes in the liver tissue were also investigated. mRNA expression of energy homeostasis genes (FTO and MCR-4) in the liver was analyzed alongside blood biomarkers. We observed higher birth weight and rapid weight gain in the test group in comparison with controls, which was consistent with the changes in mRNA and protein expression of FTO and MCR-4. BPA caused a significant, treatment-related change in the inflammatory marker C-reactive protein, lipid peroxidation, antioxidants, and lipid profile. These findings were accompanied by histological changes in the liver tissue characteristic of hepatic steatosis indicating the onset of the non-alcoholic fatty liver disease (NAFLD). Our study offers a link between exposure to BPA in parents and onset of NAFLD in their offspring.

Non-Alcoholic Fatty Liver Disease (NAFLD) Pathogenesis and Natural Products for Prevention and Treatment

Non-alcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease, affecting approximately one-quarter of the global population, and has become a world public health issue. NAFLD is a clinicopathological syndrome characterized by hepatic steatosis, excluding ethanol and other definite liver damage factors. Recent studies have shown that the development of NAFLD is associated with lipid accumulation, oxidative stress, endoplasmic reticulum stress, and lipotoxicity. A range of natural products have been reported as regulators of NAFLD in vivo and in vitro. This paper reviews the pathogenesis of NAFLD and some natural products that have been shown to have therapeutic effects on NAFLD. Our work shows that natural products can be a potential therapeutic option for NAFLD.

α-Tocopherol suppresses hepatic steatosis by increasing CPT-1 expression in a mouse model of diet-induced nonalcoholic fatty liver disease

Aim

Antioxidant therapy for with vitamin E appears to be effective for the treatment of nonalcoholic fatty liver disease　(NAFLD). However, the mechanism of action and optimal therapeutic dosage is unclear. The present study was undertaken to examine whether the effects of α‐tocopherol (α‐Toc) on NAFLD are dose‐dependent in a diet‐induced obese model.

Methods

Male mice were fed standard chow, high‐fat (HF) diet, HF diet with low‐dose, or with high dose of α‐Toc supplementation. Histological findings, triglyceride content, and the levels of protein expression related to fatty acid synthesis/oxidation such as carnitine palmitoyltransferase I (CPT‐1) of liver were evaluated. In addition, 2‐tetradecylglycidic acid (TDGA), a CPT‐1 inhibitor, was administered to mice fed HF diet with low‐dose of α‐Toc. Finally, HepG2 cells in fat‐loaded environment were treated with 0–50 μM α‐Toc.

Results

Treatment of low‐dose of α‐Toc decreased HF‐induced hepatic fat accumulation, but this finding was not observed in treatment of high dose of α‐Toc. HF‐induced reduction of CPT‐1 was attenuated with low‐dose of α‐Toc but not with high dose of α‐Toc. TDGA suppressed the improvement of histological findings in liver induced by low‐dose of α‐Toc treatment. CPT‐1 expression in HepG2 cells increased in response to low‐dose of α‐Toc, but not in high dose.

Conclusions

Dual action of α‐Toc on CPT‐1 protein levels was observed. The effect of vitamin E on NAFLD may be not be dose‐dependent.

Effects of Meal Fructose/Glucose Composition on Postprandial Glucose Appearance and Hepatic Glycogen Synthesis in Healthy Subjects

Dietary fructose overshadows glucose in promoting metabolic complications. Intestinal fructose metabolism (IFM) protects against these effects in rodents, by favoring gluconeogenesis, but the extent of IFM in humans is not known. We therefore aimed to infer the extent of IFM by comparing the contribution of dietary fructose to systemic glucose and hepatic glycogen appearance postprandially. Twelve fasting healthy subjects ingested two protein meals in random order, one supplemented with 50 g 5/95 fructose/glucose (LF) and the other with 50 g 55/45 fructose/glucose (HF). Sources of postprandial plasma glucose appearance and hepatic glycogen synthesis were determined with deuterated water. Plasma glucose excursions, as well as pre- and post-meal insulin, c-peptide, and triglyceride levels were nearly identical for both meals. The total gluconeogenic contribution to plasma glucose appearance was significantly higher for HF versus LF (65 ± 2% vs. 34 ± 3%, p < 0.001). For HF, Krebs cycle anaplerosis accounted for two-thirds of total gluconeogenesis (43 ± 2%) with one-third from Triose-P sources (22 ± 1%). With LF, three-quarters of the total gluconeogenic contribution originated via Krebs cycle anaplerosis (26 ± 2%) with one-quarter from Triose-P sources (9 ± 2%). HF and LF gave similar direct and indirect pathway contributions to hepatic glycogen synthesis. Increasing the fructose/glucose ratio had significant effects on glucose appearance sources but no effects on hepatic glycogen synthesis sources, consistent with extensive IFM. The majority of fructose carbons were converted to glucose via the Krebs cycle.

Beneficial body mass index to enhance survival outcomes in patients with early-stage hepatocellular carcinoma following microwave ablation treatment

Purpose: To identify the beneficial body mass index (BMI) for patients with hepatocellular carcinoma (HCC) to achieve longer survival time following curative microwave ablation (MWA).Methods: This retrospective study evaluated 474 patients with solitary primary HCC who underwent MWA. BMI at initial admission and other characteristics were collected. The associations of the BMI with the overall survival (OS) and disease-free survival (DFS) were analyzed by Cox proportional hazards regression analysis in multiple models. A two-piecewise linear regression model was applied to examine the threshold effect of the BMI on OS and DFS by maximized log likelihood method. The threshold level was determined by using trial and error.Results: Patients with a normal BMI range achieved improved survival outcomes but similar DFS in multiple models. In the model with adjustments of the age, size, and Charlson score, patients with BMI ≤ 22.9 and ≤24.9 kg/m² exhibited a lower death rate than patients with BMI ≤18.5 kg/m² (p < 0.05). U-shaped relationships between the BMI and OS were illustrated when the BMI was set as a continuous variable. The death prevalence decreased with an increasing BMI up to the first turning point of 21.5 and increased with an increasing BMI up to the second turning point of 23.1 (p = 0.00). The threshold effect analysis indicated that no turning point was selected in the DFS results (p = 0.10).Conclusions: The beneficial BMI level for HCC patients following MWA, with a more likely favorable survival outcome, is 21.5 to 23.1 kg/m².

Determining contributions of exogenous glucose and fructose to de novo fatty acid and glycerol synthesis in liver and adipose tissue

The de novo synthesis of triglyceride (TG) fatty acids (FA) and glycerol can be measured with stable isotope tracers. However, these methods typically do not inform the contribution of a given substrate to specific pathways on these synthetic processes. We integrated deuterated water (²H₂O) measurement of de novo lipogenesis (DNL) and glycerol-3-phosphate (GLY) synthesis from all substrates with a ¹³C nuclear magnetic resonance (NMR) method that quantifies TG FA and glycerol enrichment from a specific [U-¹³C]precursor. This allowed the [U-¹³C]precursor contribution to DNL and GLY to be estimated. We applied this method in mice to determine the contributions of fructose and glucose supplemented in the drinking water to DNL and GLY in liver, mesenteric adipose tissue (MAT) and subcutaneous adipose tissue (SCAT). In liver, fructose contributed significantly more to DNL of saturated fatty acids (SFA) and oleate as well as to GLY compared to glucose. Moreover, its contribution to SFA synthesis was significantly higher compared to that of oleate. MAT and SCAT had lower fractional rates of total DNL and GLY compared to liver and glucose was utilized more predominantly than fructose for TG synthesis in these tissues. This novel ²H₂O/¹³C integrated method revealed for the first time, tissue specific selection of substrates for DNL, particularly fructose in regard to glucose in liver. Also, this approach was able to resolve the distribution of specific FAs into the TG sn2 and sn1,3 sites. This stable isotope integrated approach yielded information so far uncovered by other lipidomic tools and should powerfully assist in other nutritional, pathological or environmental contexts.

Consensus document. Management of non-alcoholic fatty liver disease (NAFLD). Clinical practice guideline

Non-alcoholic fatty liver disease (NAFLD) is the main cause of liver diseases in Spain and the incidence is raising due to the outbreak of type 2 diabetes and obesity. This CPG suggests recommendation about diagnosis, mainly non-invasive biomarkers, and clinical management of this entity. Life-style modifications to achieve weight loss is the main target in the management of NAFLD. Low caloric Mediterranean diet and 200 minutes/week of aerobic exercise are encouraged. In non-responders patients with morbid obesity, bariatric surgery or metabolic endoscopy could be indicated. Pharmacological therapy is indicated in patients with NASH and fibrosis and non-responders to weight loss measures. NAFLD could influence liver transplantation, as a growing indication, the impact of steatosis in the graft viability, de novo NAFLD rate after OLT and a raised cardiovascular risk that modify the management of this entity. The current CPG was the result of the First Spanish NAFLD meeting in Seville.

Liver fat: a relevant target for dietary intervention? Summary of a Unilever workshop

Currently it is estimated that about 1 billion people globally have non-alcoholic fatty liver disease (NAFLD), a condition in which liver fat exceeds 5 % of liver weight in the absence of significant alcohol intake. Due to the central role of the liver in metabolism, the prevalence of NAFLD is increasing in parallel with the prevalence of obesity, insulin resistance and other risk factors of metabolic diseases. However, the contribution of liver fat to the risk of type 2 diabetes mellitus and CVD, relative to other ectopic fat depots and to other risk markers, is unclear. Various studies have suggested that the accumulation of liver fat can be reduced or prevented via dietary changes. However, the amount of liver fat reduction that would be physiologically relevant, and the timeframes and dose-effect relationships for achieving this through different diet-based approaches, are unclear. Also, it is still uncertain whether the changes in liver fat per se or the associated metabolic changes are relevant. Furthermore, the methods available to measure liver fat, or even individual fatty acids, differ in sensitivity and reliability. The present report summarises key messages of presentations from different experts and related discussions from a workshop intended to capture current views and research gaps relating to the points above.

Dietary intervention, but not losartan, completely reverses non-alcoholic steatohepatitis in obese and insulin resistant mice

Background

Dietary intervention is the cornerstone of non-alcoholic steatohepatitis (NASH) treatment. However, histological evidence of its efficacy is limited and its impact on hepatic pathways involved in NASH is underreported. The efficacy of the angiotensin receptor type 1 blocker losartan is controversial because of varying results in a few animal and human studies. We evaluated the effect of dietary intervention versus losartan on NASH and associated systemic metabolic features in a representative mouse model.

Methods

Male C57BL/6 J mice with high fat-high sucrose diet (HF-HSD) induced NASH, obesity, insulin resistance and hypercholesterolemia were subjected to dietary intervention (switch from HF-HSD to normal chow diet (NCD)) (n = 9), continuation HF-HSD together with losartan (30 mg/kg/day) (n = 9) or continuation HF-HSD only (n = 9) for 8 weeks. 9 mice received NCD during the entire experiment (20 weeks). We assessed the systemic metabolic effects and performed a detailed hepatic histological and molecular profiling. A P-value of < 0.05, using the group with continuation of HF-HSD only as control, was considered as statistically significant.

Results

Dietary intervention normalized obesity, insulin resistance, and hypercholesterolemia (for all P < 0.001), and remarkably, completely reversed all histological features of pre-existent NASH (for all P < 0.001), including fibrosis measured by quantification of collagen proportional area (P < 0.01). At the hepatic molecular level, dietary intervention targeted fibrogenesis with a normalization of collagen type I alpha 1, transforming growth factor β1, tissue inhibitor of metalloproteinase 1 mRNA levels (for all P < 0.01), lipid metabolism with a normalization of fatty acid translocase/CD36, fatty acid transport protein 5, fatty acid synthase mRNA levels (P < 0.05) and markers related to mitochondrial function with a normalization of hepatic ATP content (P < 0.05) together with sirtuin1 and uncoupling protein 2 mRNA levels (for both P < 0.001). Dietary intervention abolished p62 accumulation (P < 0.01), suggesting a restoration of autophagic flux. Losartan did not significantly affect obesity, insulin resistance, hypercholesterolemia or any histological NASH feature.

Conclusions

Dietary intervention, and not losartan, completely restores the metabolic phenotype in a representative mouse model with pre-existent NASH, obesity, insulin resistance and hypercholesterolemia.

Dietary fructose as a risk factor for non-alcoholic fatty liver disease (NAFLD)

Glucose is a major energy source for the entire body, while fructose metabolism occurs mainly in the liver. Fructose consumption has increased over the last decade globally and is suspected to contribute to the increased incidence of non-alcoholic fatty liver disease (NAFLD). NAFLD is a manifestation of metabolic syndrome affecting about one-third of the population worldwide and has progressive pathological potential for liver cirrhosis and cancer through non-alcoholic steatohepatitis (NASH). Here we have reviewed the possible contribution of fructose to the pathophysiology of NAFLD. We critically summarize the current findings about several regulators, and their potential mechanisms, that have been studied in humans and animal models in response to fructose exposure. A novel hypothesis on fructose-dependent perturbation of liver regeneration and metabolism is advanced. Fructose intake could affect inflammatory and metabolic processes, liver function, gut microbiota, and portal endotoxin influx. The role of the brain in controlling fructose ingestion and the subsequent development of NAFLD is highlighted. Although the importance for fructose (over)consumption for NAFLD in humans is still debated and comprehensive intervention studies are invited, understanding of how fructose intake can favor these pathological processes is crucial for the development of appropriate noninvasive diagnostic and therapeutic approaches to detect and treat these metabolic effects. Still, lifestyle modification, to lessen the consumption of fructose-containing products, and physical exercise are major measures against NAFLD. Finally, promising drugs against fructose-induced insulin resistance and hepatic dysfunction that are emerging from studies in rodents are reviewed, but need further validation in human patients.

Alternative treatment methods attenuate the development of NAFLD: A review of resveratrol molecular mechanisms and clinical trials

Nonalcoholic fatty liver disease (NAFLD) is considered to be one of the most common liver pathologies that occur widely among societies with a predominance of the Western dietary pattern. NAFLD may progress from hepatic steatosis to nonalcoholic steatohepatitis (NASH), subsequently leading to cirrhosis and becoming a major cause of hepatocellular carcinoma. Thus its prevention and therapy play an important role in hepatology. To our knowledge, there is no effective treatment for patients with NAFLD. The aim of this review was to summarize the results of recent alternative treatment studies conducted both on cell cultures and in vivo that concern molecular effects of resveratrol (3,5,4'-trihydroxystilbene) in the treatment of NAFLD. The precise metabolism, pharmacology, and clinical trials with different concentrations of resveratrol were described. The review also presents a brief summary of other alternative treatment methods of NAFLD and their mechanisms compared with current clinical understanding.

Effect of garlic powder consumption on body composition in patients with nonalcoholic fatty liver disease: A randomized, double-blind, placebo-controlled trial

Background:

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease that is becoming a public health problem in recent decades. Obesity and overweight play a key role in NAFLD pathogenesis. Thus, weight loss (especially body fat mass) is one component of therapeutic strategies in NAFLD. Results from experimental studies have shown that garlic (Allium sativum L.) can reduce body weight and body fat mass. However, the effect of garlic on body fat mass and weight in the human population, which is addressed in this study, is still obscure.

Materials and Methods:

In this clinical trial, 110 subjects with NAFLD were randomly assigned to the intervention or the control group. The intervention group received two garlic tablets (containing 400 mg of garlic powder) daily while the control group received placebo tablets. Dietary intake and physical activity of participants were obtained by a validated questionnaire. Body composition was measured by bioelectrical impedance analysis. Data were analyzed using SPSS software version 16.

Results:

In the intervention group, significant reductions were observed in body weight and body fat mass (P < 0.05). We also observed a significant reduction in body weight in the control group, but there were no significant changes in total body water and lean body mass in both groups (P > 0.05). In the intervention group, the percentage change in body weight was significantly greater than the control group (−2.6 vs. −0.7, P = 0.02). No serious side effects associated with the intervention were reported.

Conclusion:

Our trial suggests that garlic supplemfrom experimental studies have shown thatentation can reduce body weight and fat mass among subjects with NAFLD.

Effects of aerobic exercise on ectopic lipids in patients with growth hormone deficiency before and after growth hormone replacement therapy

Growth hormone replacement therapy (GHRT) increases exercise capacity and insulin resistance while it decreases fat mass in growth hormone-deficient patients (GHD). Ectopic lipids (intramyocellular (IMCL) and intrahepatocellular lipids (IHCL) are related to insulin resistance. The effect of GHRT on ectopic lipids is unknown. It is hypothesized that exercise-induced utilization of ectopic lipids is significantly decreased in GHD patients and normalized by GHRT. GHD (4 females, 6 males) and age/gender/waist-matched control subjects (CS) were studied. VO2max was assessed on a treadmill and insulin sensitivity determined by a two-step hyperinsulinaemic-euglycaemic clamp. Visceral (VAT) and subcutaneous (SAT) fat were quantified by MR-imaging. IHCL and IMCL were measured before and after a 2 h exercise at 50-60% of VO2max using MR-spectroscopy (∆IMCL, ∆IHCL). Identical investigations were performed after 6 months of GHRT. VO2max was similar in GHD and CS and significantly increased after GHRT; GHRT significantly decreased SAT and VAT. 2 h-exercise resulted in a decrease in IMCL (significant in CS and GHRT) and a significant increase in IHCL in CS and GHD pre and post GHRT. GHRT didn't significantly impact on ∆IMCL and ∆IHCL. We conclude that aerobic exercise affects ectopic lipids in patients and controls. GHRT increases exercise capacity without influencing ectopic lipids.

Liver Cancer: Connections with Obesity, Fatty Liver, and Cirrhosis

The burden of hepatocellular carcinoma (HCC), the most common form of liver cancer, is steadily growing because obesity, type 2 diabetes, and nonalcoholic fatty liver disease (NAFLD) are replacing viral- and alcohol-related liver disease as major pathogenic promoters. The most worrisome aspects of these new risk factors are their large spread in the general population and their link with HCC arising in noncirrhotic livers. HCC may be the presenting feature of an asymptomatic nonalcoholic steatohepatitis (NASH), the progressive form of NAFLD. The HCC risk connected to metabolic factors has been underestimated so far, and a poorer surveillance has prevented an adequate treatment. Systemic and hepatic molecular mechanisms involved in obesity- and NAFLD-induced hepatocarcinogenesis as well as potential early markers of HCC are being extensively investigated. This review summarizes current evidence linking obesity, NAFLD and liver cancer, discusses its clinical impact and describes the main mechanisms underlying this complex relationship.

GLP-1-oestrogen attenuates hyperphagia and protects from beta cell failure in diabetes-prone New Zealand obese (NZO) mice

AIMS/HYPOTHESIS

Oestrogens have previously been shown to exert beta cell protective, glucose-lowering effects in mouse models. Therefore, the recent development of a glucagon-like peptide-1 (GLP-1)-oestrogen conjugate, which targets oestrogen into cells expressing GLP-1 receptors, offers an opportunity for a cell-specific and enhanced beta cell protection by oestrogen. The purpose of this study was to compare the effects of GLP-1 and GLP-1-oestrogen during beta cell failure under glucolipotoxic conditions.

METHODS

Male New Zealand obese (NZO) mice were treated with daily s.c. injections of GLP-1 and GLP-1-oestrogen, respectively. Subsequently, the effects on energy homeostasis and beta cell integrity were measured. In order to clarify the targeting of GLP-1-oestrogen, transcription analyses of oestrogen-responsive genes in distinct tissues as well as microarray analyses in pancreatic islets were performed.

RESULTS

In contrast to GLP-1, GLP-1-oestrogen significantly decreased food intake resulting in a substantial weight reduction, preserved normoglycaemia, increased glucose tolerance and enhanced beta cell protection. Analysis of hypothalamic mRNA profiles revealed elevated expression of Pomc and Leprb. In livers from GLP-1-oestrogen-treated mice, expression of lipogenic genes was attenuated and hepatic triacylglycerol levels were decreased. In pancreatic islets, GLP-1-oestrogen altered the mRNA expression to a pattern that was similar to that of diabetes-resistant NZO females. However, conventional oestrogen-responsive genes were not different, indicating rather indirect protection of pancreatic beta cells.

CONCLUSIONS/INTERPRETATION

GLP-1-oestrogen efficiently protects NZO mice against carbohydrate-induced beta cell failure by attenuation of hyperphagia. In this regard, targeted delivery of oestrogen to the hypothalamus by far exceeds the anorexigenic capacity of GLP-1 alone.

Data from a randomized and controlled trial of LCarnitine prescription for the treatment for Non- Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) consists of a range of complication. The disease describes clinical , para clinical and pathological conditions from simple steatosis in non-alcoholic steato hepatitis (NASH) to fibrosis, cirrhosis and hepato cellular carcinoma. Therefore, it is of interest to evaluate the grade of fatty liver and Liver Function Test in NAFLD patients. We collected samples and data from 80 patients referred to gastrointestinal clinic of Emam Reza hospital with sonography diagnosed NAFLD and were evaluated in two groups in a randomized clinical trial. The effects of L-Carnitine (500 mg) prescription twice a day on liver enzymes and echogenicity changes in case group was documented and compared with the control group. The mean age of the patients was 40.7±8 in the age range of 25 to 62 years old with 66 (82.5%) male and 14 (17.5%) female patients. Data show that fatty liver changes were not significantly different in the two groups (P=0.23). It is observed that the ALT was the only enzyme with significant changes (P=0.01) after a 24-week interval. It is also noted that the difference in fatty liver sonographic grading was also significant in the two groups (P=0.0001). Thus, proper therapeutic protocols can be adopted beside diet and weight loss to control the disease trend in consideration to the significant changes observed both in enzymatic levels and sonographic grading between the two groups of patients with NAFLD.

Experimental models of non-alcoholic fatty liver disease in rats

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in the Western world, and it persists at a high prevalence. NAFLD is characterised by the accumulation of triglycerides in the liver and includes a spectrum of histopathological findings, ranging from simple fatty liver through non-alcoholic steatohepatitis (NASH) to fibrosis and ultimately cirrhosis, which may progress to hepatocellular carcinoma. The pathogenesis of NAFLD is closely related to the metabolic syndrome and insulin resistance. Understanding the pathophysiology and treatment of NAFLD in humans has currently been limited by the lack of satisfactory animal models. The ideal animal model for NAFLD should reflect all aspects of the intricate etiopathogenesis of human NAFLD and the typical histological findings of its different stages. Within the past several years, great emphasis has been placed on the development of an appropriate model for human NASH. This paper reviews the widely used experimental models of NAFLD in rats. We discuss nutritional, genetic and combined models of NAFLD and their pros and cons. The choice of a suitable animal model for this disease while respecting its limitations may help to improve the understanding of its complex pathogenesis and to discover appropriate therapeutic strategies. Considering the legislative, ethical, economical and health factors of NAFLD, animal models are essential tools for the research of this disease.

Measuring short-term liver metabolism non-invasively: postprandial and post-exercise ¹H and ³¹P MR spectroscopy

OBJECT

The objective of this study was to determine the effects of a standardized fat rich meal and subsequent exercise on liver fat content by ¹H MRS and on liver adenosine triphosphate (ATP) content by ³¹P MRS in healthy subjects.

MATERIALS AND METHODS

Hepatic ¹H and proton decoupled ³¹P MRS were performed on nine healthy subjects on a clinical 3.0 T MR imager three times during a day: after (1) an overnight fast, (2) a following standardized fat rich meal and (3) a subsequent exercise session. Blood parameters were followed during the day to serve as a reference to MRS.

RESULTS

Liver fat content increased gradually over the day (p = 0.0001) with an overall increase of 30 %. Also γ-NTP changed significantly over the day (p = 0.005). γ-NTP/tP decreased by 9 % (p = 0.019, post hoc) from the postprandial to the post-exercise state.

CONCLUSION

Our study shows that in vivo MRS can depict short lived physiological changes; entering of fat into liver cells and consumption of ATP during exercise can be measured non-invasively in healthy subjects. The physiological state may have an impact on fat and energy metabolite levels. Hepatic ¹H and ³¹P MRS studies should be performed under standardized conditions.

Exenatide improves hepatic steatosis by enhancing lipid use in adipose tissue in nondiabetic rats

AIM: To investigate the metabolic changes in skeletal muscle and/or adipose tissue in glucagon-like peptide-1-induced improvement of nonalcoholic fatty liver disease (NAFLD).

METHODS: Male Wistar rats were fed either a control diet (control group) or a high-fat diet (HFD). After 4 wk, the HFD-fed rats were subdivided into two groups; one group was injected with exenatide [HFD-Ex(+) group] and the other with saline [HFD-Ex(-) group] every day for 12 wk. The control group received saline and were fed a control diet. Changes in weight gain, energy intake, and oxygen consumption were analyzed. Glucose tolerance tests were performed after 8 wk of treatment. Histological assessments were performed in liver and adipose tissue. RNA expression levels of lipid metabolism related genes were evaluated in liver, skeletal muscle, and adipose tissue.

RESULTS: Exenatide attenuated weight gain [HFD-Ex(-) vs HFD-Ex(+)] and reduced energy intake, which was accompanied by an increase in oxygen consumption and a decrease in the respiratory exchange ratio [HFD-Ex(-) vs HFD-Ex(+)]. However, exenatide did not affect glucose tolerance. Exenatide reduced lipid content in the liver and adipose tissue. Exenatide did not affect the expression of lipid metabolism-related genes in the liver or skeletal muscle. In adipose tissue, exenatide significantly upregulated lipolytic genes, including hormone-sensitive lipase, carnitine palmitoyltransferase-1, long-chain acyl-CoA dehydrogenase, and acyl-CoA oxidase 1 [HFD-Ex(-) vs HFD-Ex(+)]. Exenatide also upregulated catalase and superoxide dismutase 2 [HFD-Ex(-) vs HFD-Ex(+)].

CONCLUSION: In addition to reducing appetite, enhanced lipid use by exenatide in adipose tissue may reduce hepatic lipid content in NAFLD, most likely by decreasing lipid influx into the liver.

Coffee consumption attenuates short-term fructose-induced liver insulin resistance in healthy men

BACKGROUND

Epidemiologic and experimental data have suggested that chlorogenic acid, which is a polyphenol contained in green coffee beans, prevents diet-induced hepatic steatosis and insulin resistance.

OBJECTIVE

We assessed whether the consumption of chlorogenic acid-rich coffee attenuates the effects of short-term fructose overfeeding, dietary conditions known to increase intrahepatocellular lipids (IHCLs), and blood triglyceride concentrations and to decrease hepatic insulin sensitivity in healthy humans.

DESIGN

Effects of 3 different coffees were assessed in 10 healthy volunteers in a randomized, controlled, crossover trial. IHCLs, hepatic glucose production (HGP) (by 6,6-d2 glucose dilution), and fasting lipid oxidation were measured after 14 d of consumption of caffeinated coffee high in chlorogenic acid (C-HCA), decaffeinated coffee high in chlorogenic acid, or decaffeinated coffee with regular amounts of chlorogenic acid (D-RCA); during the last 6 d of the study, the weight-maintenance diet of subjects was supplemented with 4 g fructose · kg(-1) · d(-1) (total energy intake ± SD: 143 ± 1% of weight-maintenance requirements). All participants were also studied without coffee supplementation, either with 4 g fructose · kg(-1) · d(-1) (high fructose only) or without high fructose (control).

RESULTS

Compared with the control diet, the high-fructose diet significantly increased IHCLs by 102 ± 36% and HGP by 16 ± 3% and decreased fasting lipid oxidation by 100 ± 29% (all P < 0.05). All 3 coffees significantly decreased HGP. Fasting lipid oxidation increased with C-HCA and D-RCA (P < 0.05). None of the 3 coffees significantly altered IHCLs.

CONCLUSIONS

Coffee consumption attenuates hepatic insulin resistance but not the increase of IHCLs induced by fructose overfeeding. This effect does not appear to be mediated by differences in the caffeine or chlorogenic acid content. This trial was registered at clinicaltrials.gov as NCT00827450.

Common carotid intima-media thickness in patients with non-alcoholic fatty liver disease: a population-based case-control study

BACKGROUND/AIMS

Metabolic syndrome is a well-known risk factor for atherosclerosis. Non-alcoholic fatty liver disease (NAFLD) has features of metabolic syndromes. This study aimed to investigate the association between NAFLD and atherosclerosis.

METHODS

In a population-based study in southern Iran, asymptomatic adult inhabitants aged more than 20 years were selected through cluster random sampling, and were screened for the presence of fatty liver and common carotid intima-media thickness (CIMT), with abdominal and cervical ultrasonography, respectively. Those with fatty liver were compared to the same number of individuals without fatty liver.

RESULTS

Two hundred and ninety individuals were found to have fatty change on abdominal ultrasonography, and were labeled NAFLD. Compared to normal individuals, NAFLD patients had significantly higher prevalence of increased CIMT (OR, 1.66; p<0.001). Those with hypertension (HTN), diabetes mellitus (DM), higher waist circumference (WC) and older ages had significantly higher prevalence of thick CIMT. Through adjusting the effects of different variables, we indicated that NAFLD could be an independent risk factor for thick common carotid intima-media (OR, 1.90; 95% CI, 1.17-3.09; p=0.009). It was also shown that age could be another independent risk factor for thick CIMT.

CONCLUSIONS

Individuals with risk factors such as HTN, DM, and high WC are prone to develop atherosclerosis of the carotid artery. The presence of NAFLD should be considered as another probable independent factor contributing to the development of carotid atherosclerosis.

The effect of aerobic exercise on intrahepatocellular and intramyocellular lipids in healthy subjects

BACKGROUND

Intrahepatocellular (IHCL) and intramyocellular (IMCL) lipids are ectopic lipid stores. Aerobic exercise results in IMCL utilization in subjects over a broad range of exercise capacity. IMCL and IHCL have been related to impaired insulin action at the skeletal muscle and hepatic level, respectively. The acute effect of aerobic exercise on IHCL is unknown. Possible regulatory factors include exercise capacity, insulin sensitivity and fat availability subcutaneous and visceral fat mass).

AIM

To concomitantly investigate the effect of aerobic exercise on IHCL and IMCL in healthy subjects, using Magnetic Resonance spectroscopy.

METHODS

Normal weight, healthy subjects were included. Visit 1 consisted of a determination of VO2max on a treadmill. Visit 2 comprised the assessment of hepatic and peripheral insulin sensitivity by a two-step hyperinsulinaemic euglycaemic clamp. At Visit 3, subcutaneous and visceral fat mass were assessed by whole body MRI, IHCL and IMCL before and after a 2-hours aerobic exercise (50% of VO(2max)) using ¹H-MR-spectroscopy.

RESULTS

Eighteen volunteers (12M, 6F) were enrolled in the study (age, 37.6±3.2 years, mean±SEM; VO(2max), 53.4±2.9 mL/kg/min). Two hours aerobic exercise resulted in a significant decrease in IMCL (-22.6±3.3, % from baseline) and increase in IHCL (+34.9±7.6, % from baseline). There was no significant correlation between the exercise-induced changes in IMCL and IHCL and exercise capacity, subcutaneous and visceral fat mass and hepatic or peripheral insulin sensitivity.

CONCLUSIONS

IMCL and IHCL are flexible ectopic lipid stores that are acutely influenced by physical exercise, albeit in different directions.

TRIAL REGISTRATION

ClinicalTrial.gov NCT00491582.

Dietary walnut oil modulates liver steatosis in the obese Zucker rat

Purpose

Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of the metabolic syndrome. We aimed to clarify the impact of dietary walnut oil versus animal fat on hepatic steatosis, representing the initial step of multistage pathogenesis of NAFLD, in Zucker obese rats.

Methods

Zucker lean ad libitum (a.l.), Zucker obese a.l. or Zucker obese pair fed (p.f.) to the lean received isocaloric diets containing 8 % walnut oil (W8), W14 or 14 % lard (L14) (n = 10/group). Body weight, clinical serology, liver weight, lipid content and fatty acid composition and hepatic lipid metabolism-related transcripts were evaluated.

Results

Compared to lean, Zucker obese a.l. and p.f. showed hepatic triacylglyceride (TAG) accumulation. In Zucker obese p.f., W14 compared to W8 and L14 reduced liver lipids, TAG as well as hepatic omega-6 (n-6)/n-3 ratio and SCD activity index [(C18:0 + C18:1)/C18:0 ratio] paralleled by decreased lipoprotein lipase mRNA in obese p.f. and elevated microsomal triglyceride transfer protein mRNA in lean and obese. Further, W14 elevated the fasting blood TAG and reduced cholesterol levels in obese.

Conclusions

In our model, consumption of W14 inhibited hepatic lipid accumulation along with modulated hepatic gene expression implicated in hepatic fatty acid influx or lipoprotein assembly. These results provide first indication that dietary lipids from walnut oil are modulators of hepatic steatosis as the initial step of progressive NAFLD pathogenesis.

Iron overload causes oxidative stress and impaired insulin signaling in AML-12 hepatocytes

BACKGROUND

Iron overload is associated with increased severity of nonalcoholic fatty liver disease (NAFLD) including progression to nonalcoholic steatohepatitis and hepatocellular carcinoma.

AIMS

To identify potential role(s) of iron in NAFLD, we measured its effects on pathways of oxidative stress and insulin signaling in AML-12 mouse hepatocytes.

METHODS

Rapid iron overload was induced with 50 μM ferric ammonium citrate and 8-hydroxyquinoline. Insulin response was measured by Western blot of phospho-protein kinase B. Lipid content was determined by staining with Oil Red O. Reactive oxygen species (ROS) were measured by flow cytometry using 5-(and 6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate. Oxidative stress was measured by Western blots for phospho-jnk and phospho-p38.

RESULTS

Iron increased ROS (p < 0.001) and oxidative stress (p < 0.001) and decreased insulin signaling by 33 % (p < 0.001). Treatment with stearic or oleic acids (200 μM) increased cellular lipid content and differentially modulated effects of iron. Stearic acid potentiated iron-induced ROS levels by two-fold (p < 0.05) and further decreased insulin response 59 % (p < 0.05) versus iron alone. In contrast, cells treated with oleic acid were protected against iron-mediated injury; ROS levels were decreased by half (p < 0.01) versus iron alone while insulin response was restored to control (untreated) levels. The anti-oxidant curcumin reduced effects of iron on insulin signaling, ROS, and oxidative stress (p < 0.01). Curcumin was similarly effective in cells treated with both stearic acid and iron.

CONCLUSIONS

An in vitro model of NAFLD progression is described in which iron-induced oxidative stress inhibits insulin signaling. Pathophysiological effects of iron were increased by saturated fat and decreased by curcumin.

A Palaeolithic-type diet causes strong tissue-specific effects on ectopic fat deposition in obese postmenopausal women

OBJECTIVES

Ectopic fat accumulation in liver and skeletal muscle may be an essential link between abdominal obesity, insulin resistance and increased risk of cardiovascular disease after menopause. We hypothesized that a diet containing a relatively high content of protein and unsaturated fat [mainly monounsaturated fatty acids (MUFAs)] but limited carbohydrates and saturated fat would reduce lipid content in liver and muscle and increase insulin sensitivity in postmenopausal women.

SUBJECTS

Ten healthy, nonsmoking postmenopausal women with a body mass index (BMI) >27 (28-35) kg m(-2) were included in the study.

INTERVENTIONS

Participants were instructed to consume an ad libitum Palaeolithic-type diet intended to provide approximately 30 energy percentage (E%) protein, 40 E% fat (mainly MUFAs) and 30 E% carbohydrate. Intramyocellular lipid (IMCL) levels in calf muscles and liver triglyceride levels were quantified using proton magnetic resonance spectroscopy ((1) H-MRS) before and 5 weeks after dietary intervention. Insulin sensitivity was estimated by homoeostasis model assessment (HOMA) indices and the euglycaemic hyperinsulinaemic clamp technique.

RESULTS

Mean energy intake decreased by 25% with a weight loss of 4.5 kg. BMI, waist and hip circumference, waist/hip ratio and abdominal sagittal diameter also decreased significantly, as did diastolic blood pressure (mean -7 mmHg), levels of fasting serum glucose, cholesterol, triglycerides, LDL/HDL cholesterol, apolipoprotein B (ApoB) and apolipoprotein A1 (ApoA1), urinary C-peptide and HOMA indices. Whole-body insulin sensitivity did not change. Liver triglyceride levels decreased by 49%, whereas IMCL levels in skeletal muscle were not significantly altered.

CONCLUSIONS

A modified Palaeolithic-type diet has strong and tissue-specific effects on ectopic lipid deposition in postmenopausal women.

Sterol regulatory element-binding factor 2 (SREBF-2) predicts 7-year NAFLD incidence and severity of liver disease and lipoprotein and glucose dysmetabolism

We prospectively assessed the impact of a sterol regulatory element-binding factor-2 (SREBF-2) polymorphism on the risk of developing nonalcoholic fatty liver disease (NAFLD) and on liver histology and lipoprotein and glucose metabolism in biopsy-proven NAFLD. In a population-based study, we followed 175 nonobese, nondiabetic participants without NAFLD or metabolic syndrome at baseline, characterized for the SREBF-2 rs133291 C/T polymorphism, dietary habits, physical activity, adipokines, C-reactive protein (CRP), and endothelial adhesion molecules. A comparable cohort of NAFLD patients underwent liver biopsy, an oral glucose tolerance test with minimal model analysis to yield glucose homeostasis parameters, and an oral fat tolerance test with measurement of plasma lipoproteins, adipokines, and cytokeratin-18 fragments. After 7 years, 27% of subjects developed NAFLD and 5% developed diabetes. SREBF-2 predicted incident NAFLD and diabetes and CRP and endothelial adhesion molecule changes. In biopsy-proven NAFLD patients, SREBF-2 predicted nonalcoholic steatohepatitis (odds ratio 2.92 [95% CI 2.08-4.18], P = 0.002) and the severity of tissue insulin resistance, β-cell dysfunction, and oral fat intolerance (characterized by higher postprandial lipemia, cholesterol enrichment of triglyceride-rich lipoproteins and oxidized LDLs, HDL cholesterol fall, adipokine imbalance, and postprandial apoptosis activation). An SREBF-2 polymorphism predisposes individuals to NAFLD and associated cardiometabolic abnormalities and affects liver histology and glucose and lipid metabolism in biopsy-proven NAFLD.

Genetic signatures in choline and 1-carbon metabolism are associated with the severity of hepatic steatosis

Choline metabolism is important for very low-density lipoprotein secretion, making this nutritional pathway an important contributor to hepatic lipid balance. The purpose of this study was to assess whether the cumulative effects of multiple single nucleotide polymorphisms (SNPs) across genes of choline/1-carbon metabolism and functionally related pathways increase susceptibility to developing hepatic steatosis. In biopsy-characterized cases of nonalcoholic fatty liver disease and controls, we assessed 260 SNPs across 21 genes in choline/1-carbon metabolism. When SNPs were examined individually, using logistic regression, we only identified a single SNP (PNPLA3 rs738409) that was significantly associated with severity of hepatic steatosis after adjusting for confounders and multiple comparisons (P=0.02). However, when groupings of SNPs in similar metabolic pathways were defined using unsupervised hierarchical clustering, we identified groups of subjects with shared SNP signatures that were significantly correlated with steatosis burden (P=0.0002). The lowest and highest steatosis clusters could also be differentiated by ethnicity. However, unique SNP patterns defined steatosis burden irrespective of ethnicity. Our results suggest that analysis of SNP patterns in genes of choline/1-carbon metabolism may be useful for prediction of severity of steatosis in specific subsets of people, and the metabolic inefficiencies caused by these SNPs should be examined further.

Does fructose consumption contribute to non-alcoholic fatty liver disease?

Fructose is mainly consumed with added sugars (sucrose and high fructose corn syrup), and represents up to 10% of total energy intake in the US and in several European countries. This hexose is essentially metabolized in splanchnic tissues, where it is converted into glucose, glycogen, lactate, and, to a minor extent, fatty acids. In animal models, high fructose diets cause the development of obesity, insulin resistance, diabetes mellitus, and dyslipidemia. Ectopic lipid deposition in the liver is an early occurrence upon fructose exposure, and is tightly linked to hepatic insulin resistance. In humans, there is strong evidence, based on several intervention trials, that fructose overfeeding increases fasting and postprandial plasma triglyceride concentrations, which are related to stimulation of hepatic de novo lipogenesis and VLDL-TG secretion, together with decreased VLDL-TG clearance. However, in contrast to animal models, fructose intakes as high as 200 g/day in humans only modestly decreases hepatic insulin sensitivity, and has no effect on no whole body (muscle) insulin sensitivity. A possible explanation may be that insulin resistance and dysglycemia develop mostly in presence of sustained fructose exposures associated with changes in body composition. Such effects are observed with high daily fructose intakes, and there is no solid evidence that fructose, when consumed in moderate amounts, has deleterious effects. There is only limited information regarding the effects of fructose on intrahepatic lipid concentrations. In animal models, high fructose diets clearly stimulate hepatic de novo lipogenesis and cause hepatic steatosis. In addition, some observations suggest that fructose may trigger hepatic inflammation and stimulate the development of hepatic fibrosis. This raises the possibility that fructose may promote the progression of non-alcoholic fatty liver disease to its more severe forms, i.e. non-alcoholic steatohepatitis and cirrhosis. In humans, a short-term fructose overfeeding stimulates de novo lipogenesis and significantly increases intrahepatic fat concentration, without however reaching the proportion encountered in non-alcoholic fatty liver diseases. Whether consumption of lower amounts of fructose over prolonged periods may contribute to the pathogenesis of NAFLD has not been convincingly documented in epidemiological studies and remains to be further assessed.

Dietary protein affects gene expression and prevents lipid accumulation in the liver in mice

Background and Aims

High protein (HP) diets are suggested to positively modulate obesity and associated increased prevalence of non-alcoholic fatty liver (NAFLD) disease in humans and rodents. The aim of our study was to detect mechanisms by which a HP diet affects hepatic lipid accumulation.

Methods

To investigate the acute and long term effect of high protein ingestion on hepatic lipid accumulation under both low and high fat (HF) conditions, mice were fed combinations of high (35 energy%) or low (10 energy%) fat and high (50 energy%) or normal (15 energy%) protein diets for 1 or 12 weeks. Effects on body composition, liver fat, VLDL production rate and the hepatic transcriptome were investigated.

Results

Mice fed the HP diets displayed a lower body weight, developed less adiposity and decreased hepatic lipid accumulation, which could be attributed to a combination of several processes. Next to an increased hepatic VLDL production rate, increased energy utilisation due to enhanced protein catabolic processes, such as transamination, TCA cycle and oxidative phosphorylation was found upon high protein ingestion.

Conclusion

Feeding a HP diet prevented the development of NAFLD by enhancing lipid secretion into VLDL particles and a less efficient use of ingested calories.

High-carbohydrate diets induce hepatic insulin resistance to protect the liver from substrate overload

In population studies hepatic steatosis in subjects with Non-alcoholic fatty liver disease (NAFLD) is strongly associated with insulin resistance. This association has encouraged debate whether hepatic steatosis is the cause or the consequence of hepatic insulin resistance? Although genome-wide studies have identified several gene variants associated with either hepatic steatosis or type 2 diabetes, no variants have been identified associated with both hepatic steatosis and insulin resistance. Here, the hypothesis is proposed that high-carbohydrate diets contribute to the association between hepatic steatosis and insulin resistance through activation of the transcription factor ChREBP (Carbohydrate response element binding protein). Postprandial hyperglycaemia raises the hepatic concentrations of phosphorylated intermediates causing activation of ChREBP and induction of its target genes. These include not only enzymes of glycolysis and lipogenesis that predispose to hepatic steatosis but also glucose 6-phosphatase (G6PC) that catalyses the final reaction in glucose production and GCKR, the inhibitor of hepatic glucokinase that curtails hepatic glucose uptake. Induction of G6PC and GCKR manifests as hepatic glucose intolerance or insulin resistance. Induction of these two genes by high glucose serves to safeguard intrahepatic homeostasis of phosphorylated intermediates. The importance of GCKR in this protective mechanism is supported by "less-active" GCKR variants in association not only with hepatic steatosis and hyperuricaemia but also with lower fasting plasma glucose and decreased insulin resistance. This supports a role for GCKR in restricting hepatic glucose phosphorylation to maintain intrahepatic homeostasis. Pharmacological targeting of the glucokinase-GCKR interaction can favour either glucose clearance by the liver or intrahepatic metabolite homeostasis.

Serum ferritin levels predict incident non-alcoholic fatty liver disease in healthy Korean men

Little research has been done to examine the temporal relationship between serum ferritin and the development of nonalcoholic fatty liver disease. The aim of this study was to examine whether serum ferritin levels predict incident fatty liver in non-diabetic men. The study cohort comprised 2410 healthy Korean male who were aged 30 to 59years old with no evidence of ultrasonographically detectable fatty liver (USFL) at baseline. Alcohol intake was assessed with a self-reported questionnaire. At each visit, biochemical and anthropometric measurements and abdominal ultrasonography were done. Cox proportional hazard models were used to calculate the adjusted hazard ratios in separate models for USFL. During 7545.9 person-years of follow-up, 586 participants developed USFL. The hazard ratio (95% confidence interval) for incident USFL comparing the highest quartile of serum ferritin level to the lowest quartile was 1.54 (1.21-1.94) after adjusting for age, body mass index, smoking, alcohol intake, and exercise. That association remained significant after further adjustment for cardiovascular risk factors and in time-dependent models. The association between serum ferritin and incident USFL was still significant in the non-overweight group or the no current smoker group. Serum ferritin level was an independent risk factor of incident fatty liver detected by ultrasonography even in non-obese, healthy Korean men. Increased serum ferritin levels appear to be an early predictor for incident fatty liver.

Atorvastatin improves disease activity of nonalcoholic steatohepatitis partly through its tumour necrosis factor-α-lowering property

BACKGROUND

We have previously found that atorvastatin decreases liver injury markers in patients with nonalcoholic steatohepatitis. However, how atorvastatin treatment ameliorates the disease activity in nonalcoholic steatohepatitis patients remains unknown.

AIMS

We examined here which anthropometric, metabolic and inflammatory variables were improved and related with amelioration of disease activity in atorvastatin-treated nonalcoholic steatohepatitis patients.

METHODS

Forty-two biopsy-proven nonalcoholic steatohepatitis patients with dyslipidemia were enrolled. Patients were treated with atorvastatin (10mg/day) for 12 months.

RESULTS

Atorvastatin significantly decreased liver transaminase, γ-glutamyl transpeptidase, low-density lipoprotein-cholesterol, triglycerides, type IV collagen, and tumour necrosis factor-α levels, whilst it increased adiponectin and high-density lipoprotein-cholesterol. Atorvastatin improved nonalcoholic fatty liver disease activity score and increased liver to spleen density ratio. Multiple stepwise regression analysis revealed that γ-glutamyl transpeptidase, tumour necrosis factor-α and liver to spleen density ratio (inversely) were independently associated with nonalcoholic fatty liver disease activity score. Aspartate aminotransferase, low-density lipoprotein-cholesterol and nonalcoholic fatty liver disease activity score were independent determinants of decreased liver to spleen density ratio.

CONCLUSION

The present study suggests that atorvastatin improves the disease activity of nonalcoholic steatohepatitis partly via its tumour necrosis factor-α-lowering property.

Effects of n-6 PUFAs compared with SFAs on liver fat, lipoproteins, and inflammation in abdominal obesity: a randomized controlled trial

BACKGROUND

Replacing SFAs with vegetable PUFAs has cardiometabolic benefits, but the effects on liver fat are unknown. Increased dietary n-6 PUFAs have, however, also been proposed to promote inflammation-a yet unproven theory.

OBJECTIVE

We investigated the effects of PUFAs on liver fat, systemic inflammation, and metabolic disorders.

DESIGN

We randomly assigned 67 abdominally obese subjects (15% had type 2 diabetes) to a 10-wk isocaloric diet high in vegetable n-6 PUFA (PUFA diet) or SFA mainly from butter (SFA diet), without altering the macronutrient intake. Liver fat was assessed by MRI and magnetic resonance proton (1H) spectroscopy (MRS). Proprotein convertase subtilisin/kexin type-9 (PCSK9, a hepatic LDL-receptor regulator), inflammation, and adipose tissue expression of inflammatory and lipogenic genes were determined.

RESULTS

A total of 61 subjects completed the study. Body weight modestly increased but was not different between groups. Liver fat was lower during the PUFA diet than during the SFA diet [between-group difference in relative change from baseline; 16% (MRI; P < 0.001), 34% (MRS; P = 0.02)]. PCSK9 (P = 0.001), TNF receptor-2 (P < 0.01), and IL-1 receptor antagonist (P = 0.02) concentrations were lower during the PUFA diet, whereas insulin (P = 0.06) tended to be higher during the SFA diet. In compliant subjects (defined as change in serum linoleic acid), insulin, total/HDL-cholesterol ratio, LDL cholesterol, and triglycerides were lower during the PUFA diet than during the SFA diet (P < 0.05). Adipose tissue gene expression was unchanged.

CONCLUSIONS

Compared with SFA intake, n-6 PUFAs reduce liver fat and modestly improve metabolic status, without weight loss. A high n-6 PUFA intake does not cause any signs of inflammation or oxidative stress. Downregulation of PCSK9 could be a novel mechanism behind the cholesterol-lowering effects of PUFAs. This trial was registered at clinicaltrials.gov as NCT01038102.

Toward a unifying hypothesis of metabolic syndrome

Despite a lack of consistent diagnostic criteria, the metabolic syndrome (MetS) is increasingly evident in children and adolescents, portending a tsunami of chronic disease and mortality as this generation ages. The diagnostic criteria for MetS apply absolute cutoffs to continuous variables and fail to take into account aging, pubertal changes, and race/ethnicity. We attempt to define MetS mechanistically to determine its specific etiologies and to identify targets for therapy. Whereas the majority of studies document a relationship of visceral fat to insulin resistance, ectopic liver fat correlates better with dysfunctional insulin dynamics from which the rest of MetS derives. In contrast to the systemic metabolism of glucose, the liver is the primary metabolic clearinghouse for 4 specific foodstuffs that have been associated with the development of MetS: trans-fats, branched-chain amino acids, ethanol, and fructose. These 4 substrates (1) are not insulin regulated and (2) deliver metabolic intermediates to hepatic mitochondria without an appropriate "pop-off" mechanism for excess substrate, enhancing lipogenesis and ectopic adipose storage. Excessive fatty acid derivatives interfere with hepatic insulin signal transduction. Reactive oxygen species accumulate, which cannot be quenched by adjacent peroxisomes; these reactive oxygen species reach the endoplasmic reticulum, leading to a compensatory process termed the "unfolded protein response," driving further insulin resistance and eventually insulin deficiency. No obvious drug target exists in this pathway; thus, the only rational therapeutic approaches remain (1) altering hepatic substrate availability (dietary modification), (2) reducing hepatic substrate flux (high fiber), or (3) increasing mitochondrial efficiency (exercise).

Long-term dietary potential renal acid load during adolescence is prospectively associated with indices of nonalcoholic fatty liver disease in young women

Nonalcoholic fatty liver disease (NAFLD), frequently already present in young subjects, has been linked to reduced growth hormone levels and signaling. Similar hormonal changes occur during metabolic acidosis (MA), which may thus contribute to an increased NAFLD risk. Because subclinical MA can be diet induced, we aimed to examine whether a higher diet-dependent acid load during adolescence is prospectively associated with several currently used NAFLD surrogates in young adulthood. Dietary acidity during adolescence (boys:10-15 y, girls: 9-14 y) was calculated as potential renal acid load (PRAL) from at least three 3-d weighed dietary records according to a published algorithm considering dietary protein and minerals in 145 healthy participants. Routine measurements derived from blood analysis and anthropometric data in participants' young adulthood (18-25 y) were used to determine the NAFLD surrogates alanine-aminotransferase (ALT), hepatic steatosis index (HSI), and fatty liver index (FLI). Sex-stratified linear regression models, adjusted for dietary fiber, saturated fat, protein, and adolescent BMI SD scores, were run with PRAL as the independent variable. Dietary PRAL during puberty was positively associated with ALT (P = 0.02), HSI (P = 0.002), and FLI (P = 0.005) in adult females but not males. Females with an adolescent dietary acid load in the highest tertile had 3.5, 4.4, and 4.5 higher values of ALT, HSI, and FLI as adults, respectively, compared to females with the lowest PRAL. The present findings suggest that higher dietary acidity in adolescence may be prospectively associated with hepatic lipid accumulation in females. Whether this relationship is due to the higher proton load or rather represents an unhealthy dietary pattern requires further investigation.

Rosiglitazone versus rosiglitazone and metformin versus rosiglitazone and losartan in the treatment of nonalcoholic steatohepatitis in humans: a 12-month randomized, prospective, open- label trial

Medication combinations that improve the efficacy of thiazolidinediones or ameliorate weight-gain side effects of therapy represent an attractive potential treatment for (NASH). The aim of this randomized, open-label trial was to assess the efficacy of rosiglitazone and metformin in combination versus rosiglitazone and losartan, compared to rosiglitazone alone, after 48 weeks of therapy. A total of 137 subjects with biopsy-proven NASH were enrolled and randomly assigned to receive either 4 mg twice-daily of rosiglitazone, 4 mg of rosiglitazone and 500 mg of metformin twice-daily, or 4 mg of rosiglitazone twice-daily and 50 mg of losartan once-daily for 48 weeks. Patients were screened for other etiologies of chronic liver disease, including daily alcohol intake in excess of 20 g. Repeat liver biopsy was performed after 48 weeks of therapy and reviewed in a blinded fashion by a single expert hepatopathologist. The primary aim of the study was to assess for differences between treatment groups in the improvement of steatosis, hepatocellular inflammation, and fibrosis. In total, 108 subjects completed the trial. Primary outcome revealed no significant difference between treatment groups in all histologic parameters (steatosis, P = 0.137; hepatocellular inflammation, P = 0.320; fibrosis, P = 0.229). Overall improvement in steatosis, hepatocellular inflammation, ballooning degeneration, and fibrosis was observed (P ≤ 0.001). Serum aminotransferases were reduced in all three groups (P < 0.001 within treatment, P > 0.05 between groups). Metformin did not significantly mitigate weight gain (P = 0.051).

CONCLUSIONS

Forty-eight weeks of combination therapy with rosiglitazone and metformin or rosiglitazone and losartan confers no greater benefit than rosiglitazone alone with respect to histopathology.

Nutritional recommendations for patients with non-alcoholic fatty liver diseases

Fatty liver is the most common liver disease worldwide. Patients with fatty liver disease die primarily from cardiovascular disease and not from chronic liver diseases. Hyperglycemia and hyperinsulinemia induce lipogenesis, thereby increasing the hepatic pool of fatty acids. This pool is also increased by increased delivery of fatty acids through the diet or lipolysis in adipose tissue. Nutritional consultations and lifestyle modification are important in the treatment of non-alcoholic fatty liver disease (NAFLD). Among the dietary constituents, combination of vitamin D, vitamin E, and omega-3 fatty acids shows promise for the treatment of NAFLD.

Exotic Fruits as Therapeutic Complements for Diabetes, Obesity and Metabolic Syndrome

The prevalence and severity of obesity, type 2-diabetes, and the resultant metabolic syndrome are rapidly increasing. As successful preventive and therapeutic strategies for these life-threatening health ailments often come with adverse side effects, nutritional elements are widely used in many countries as preventive therapies to prevent or manage metabolic syndrome. Fruits are important dietary components, and contain various bioactive constituents. Many of these constituents have been proven to be useful to manage and treat various chronic diseases such as diabetes, obesity, cancer and cardiovascular diseases. Although exotic fruits are understudied throughout the world due to their limited regional presence, many studies reveal their potent ability to ameliorate metabolic derangements and the resultant conditions i.e. diabetes and obesity. The aim of this article is to review the role of exotic fruits and their constituents in the regulation of metabolic functions, which can beneficially alter diabetes and obesity pathophysiology.

Hepatic insulin resistance in mice with hepatic overexpression of diacylglycerol acyltransferase 2

Mice overexpressing acylCoA:diacylglycerol (DAG) acyltransferase 2 in the liver (Liv-DGAT2) have been shown to have normal hepatic insulin responsiveness despite severe hepatic steatosis and increased hepatic triglyceride, diacylglycerol, and ceramide content, demonstrating a dissociation between hepatic steatosis and hepatic insulin resistance. This led us to reevaluate the role of DAG in causing hepatic insulin resistance in this mouse model of severe hepatic steatosis. Using hyperinsulinemic-euglycemic clamps, we studied insulin action in Liv-DGAT2 mice and their wild-type (WT) littermate controls. Here, we show that Liv-DGAT2 mice manifest severe hepatic insulin resistance as reflected by decreased suppression of endogenous glucose production (0.8 ± 41.8 vs. 87.7 ± 34.3% in WT mice, P < 0.01) during the clamps. Hepatic insulin resistance could be attributed to an almost 12-fold increase in hepatic DAG content (P < 0.01) resulting in a 3.6-fold increase in protein kinase Cε (PKCε) activation (P < 0.01) and a subsequent 52% decrease in insulin-stimulated insulin receptor substrate 2 (IRS-2) tyrosine phosphorylation (P < 0.05), as well as a 64% decrease in fold increase pAkt/Akt ratio from basal conditions (P < 0.01). In contrast, hepatic insulin resistance in these mice was not associated with increased endoplasmic reticulum (ER) stress or inflammation. Importantly, hepatic insulin resistance in Liv-DGAT2 mice was independent of differences in body composition, energy expenditure, or food intake. In conclusion, these findings strengthen the link between hepatic steatosis and hepatic insulin resistance and support the hypothesis that DAG-induced PKCε activation plays a major role in nonalcoholic fatty liver disease (NAFLD)-associated hepatic insulin resistance.