Obesity and nonalcoholic fatty liver disease

Influence of dietary macronutrients on liver fat accumulation and metabolism

The liver is a principal metabolic organ within the human body and has a major role in regulating carbohydrate, fat, and protein metabolism. With increasing rates of obesity, the prevalence of non-alcoholic fatty liver disease (NAFLD) is growing. It remains unclear why NAFLD, which is now defined as the hepatic manifestation of the metabolic syndrome, develops but lifestyle factors such as diet (ie, total calorie and specific nutrient intakes), appear to play a key role. Here we review the available observational and intervention studies that have investigated the influence of dietary macronutrients on liver fat content. Findings from observational studies are conflicting with some reporting that relative to healthy controls, patients with NAFLD consume diets higher in total fat/saturated fatty acids, whilst others find they consume diets higher in carbohydrates/sugars. From the limited number of intervention studies that have been undertaken, a consistent finding is a hypercaloric diet, regardless of whether the excess calories have been provided either as fat, sugar, or both, increases liver fat content. In contrast, a hypocaloric diet decreases liver fat content. Findings from both hyper- and hypo-caloric feeding studies provide some suggestion that macronutrient composition may also play a role in regulating liver fat content and this is supported by data from isocaloric feeding studies; fatty acid composition and/or carbohydrate content/type appear to influence whether there is accrual of liver fat or not. The mechanisms by which specific macronutrients, when consumed as part of an isocaloric diet, cause a change in liver fat remain to be fully elucidated.

What Is Lipotoxicity?

Enlarged fat cells in obese adipose tissue diminish capacity to store fat and are resistant to the anti-lipolytic effect of insulin. Insulin resistance (IR)-associated S-nitrosylation of insulin-signaling proteins increases in obesity. In accordance with the inhibition of insulin-mediated anti-lipolytic action, plasma free fatty acid (FFA) levels increase. Additionally, endoplasmic reticulum stress stimuli induce lipolysis by activating cyclic adenosine monophosphate/Protein kinase A (cAMP/PKA) and extracellular signal-regulated kinase ½ (ERK1/2) signaling in adipocytes. Failure of packaging of excess lipid into lipid droplets causes chronic elevation of circulating fatty acids, which can reach to toxic levels within non-adipose tissues. Deleterious effects of lipid accumulation in non-adipose tissues are known as lipotoxicity. In fact, triglycerides may also serve a storage function for long-chain non-esterified fatty acids and their products such as ceramides and diacylglycerols (DAGs). Thus, excess DAG, ceramide and saturated fatty acids in obesity can induce chronic inflammation and have harmful effect on multiple organs and systems. In this context, chronic adipose tissue inflammation, mitochondrial dysfunction and IR have been discussed within the scope of lipotoxicity.

Differences in characteristics of glucose intolerance between patients with NAFLD and chronic hepatitis C as determined by CGMS

Glucose intolerance frequently develops in accordance with the progression of chronic liver disease. However, differences in the characteristics of glucose intolerance between patients with nonalcoholic fatty liver disease (NAFLD) and those with chronic hepatitis C (C-CH) remain incompletely understood. To clarify these differences, patients with NAFLD (n = 37) and C-CH (n = 40) were evaluated with a continuous glucose monitoring system (CGMS). In the patients with NAFLD, Maximum blood glucose concentration and blood glucose swings were significantly correlated with hepatic fibrosis markers. In the patients with C-CH, however, those two CGMS parameters were negatively correlated with the serum albumin (ALB) concentration. Furthermore, in the patients with C-CH with an ALB concentration of ≤4.0 g/dl, those two CGMS parameters were negatively correlated with the ALB concentration with greater statistical significance. In conclusion, obvious differences in the characteristics of glucose intolerance between patients with NAFLD and those with C-CH were clarified. In patients with NAFLD, glucose intolerance gradually progressed in accordance with the progression of hepatic fibrosis. In those with C-CH, glucose intolerance suddenly developed upon the appearance of hypoalbuminaemia.

Clinical usefulness of controlled attenuation parameter to screen hepatic steatosis for potential donor of living donor liver transplant

OBJECTIVE

Hepatic steatosis is associated with an increased risk of graft loss. Although the controlled attenuation parameter (CAP), a process based on transient elastography, has been suggested as a noninvasive method of assessing hepatic steatosis, to date, there is no study on the usefulness of CAP as a single screening tool for detecting hepatic steatosis in potential living donor liver. We evaluated the accuracy of CAP for detecting hepatic steatosis in potential liver donors.

PATIENTS AND METHODS

All potential donors of living-donor liver transplantation who underwent a CAP assessment and ultrasonography-guided liver biopsy were enrolled. The steatosis grades were as follows: S0 less than 5%; S1, 5-33%; S2, 34-66%; and S3, more than 66%.

RESULTS

According to the liver biopsies, 19 (34.5%) patients had S0, 30 (54.5%) patients had S1, and 6 (11.0%) patients had S2. The CAP value was correlated positively with BMI (r=0.242, P=0.01), waist circumference (r=0.268, P=0.006), hip circumference (r=0.334, P=0.001), Magnetic resonance fat signal fraction (r=0.465, P=0.001), and histologic steatosis grade (r=0.542, P=0.001). The area under the receiver operator characteristic curve for the diagnosis of steatosis (≥S2) by CAP was 0.88 (sensitivity 83.3% and specificity 81.6% at a cutoff value of 276 dB/m, P<0.0001).

CONCLUSION

This study suggests that CAP, as a simple and noninvasive preoperative assessment for hepatic steatosis, may be sufficient for identifying and thus excluding significant hepatic steatosis (>33%) in potential liver donors.

Prevalence and Correlates of Suspected Nonalcoholic Fatty Liver Disease in Chinese Children

Nonalcoholic fatty liver disease (NAFLD) has become a serious public health problem worldwide; however, the availability of information on the prevalence of NAFLD in the general pediatric population is still limited. The primary aim of this study was to reveal the prevalence and correlates of suspected NAFLD in Chinese children at the national level. Data from the China Health and Nutrition Surveys (CHNS) was used. Weight, height, waist circumference (WC), blood pressure (BP) were measured for children aged 7–18 years. Blood samples were collected and analyzed. Children were classified as having suspected NAFLD if common causes of liver disease were excluded, and serum alanine aminotransferase (ALT) values were above the established thresholds (>22.1 IU/L for girls and >25.8 IU/L for boys). A percentage of 9.03% (75 out of 831) of Chinese children was found to have suspected NAFLD. Overweight and obesity according to BMI percentiles, abdominal obesity, hyperuricemia (uric acid (UA) > 327 μmol/L), and elevated total cholesterol (TC) were all detected as the correlates of childhood suspected NAFLD when adjusting for other factors. Our study revealed the prevalence of suspected NAFLD in general Chinese children at the national level for the first time. Our findings indicate that suspected NAFLD in children is associated with increasing childhood morbidities, further studies are needed to better understand the prevalence of childhood NAFLD and its correlates, and large-scale programs should be launched to screen NAFLD in the pediatric population in China.

Obesity-induced hepatic steatosis is mediated by endoplasmic reticulum stress in the subfornical organ of the brain

Nonalcoholic fatty liver disease (NAFLD), characterized by an excess accumulation of hepatic triglycerides, is a growing health epidemic. While ER stress in the liver has been implicated in the development of NAFLD, the role of brain ER stress - which is emerging as a key contributor to a number of chronic diseases including obesity - in NAFLD remains unclear. These studies reveal that chemical induction of ER stress in the brain caused hepatomegaly and hepatic steatosis in mice. Conversely, pharmacological reductions in brain ER stress in diet-induced obese mice rescued NAFLD independent of body weight, food intake, and adiposity. Evaluation of brain regions involved revealed robust activation of ER stress biomarkers and ER ultrastructural abnormalities in the circumventricular subfornical organ (SFO), a nucleus situated outside of the blood-brain-barrier, in response to high-fat diet. Targeted reductions in SFO-ER stress in obese mice via SFO-specific supplementation of the ER chaperone 78-kDa glucose-regulated protein ameliorated hepatomegaly and hepatic steatosis without altering body weight, food intake, adiposity, or obesity-induced hypertension. Overall, these findings indicate a novel role for brain ER stress, notably within the SFO, in the pathogenesis of NAFLD.

Childhood Adiposity and Nonalcoholic Fatty Liver Disease in Adulthood

OBJECTIVE

To investigate the association of childhood adiposity and change in adiposity status from childhood to adulthood with nonalcoholic fatty liver disease (NAFLD) and abnormal liver enzyme levels in adulthood.

METHODS

Data were obtained from a population-based cohort of children aged 6 to 18 years started in 1987. From 2010 to 2014, 1350 subjects (aged 28-45 years) from the original cohort were followed. Childhood overweight and obesity were defined using BMI and subscapular skinfold thickness, respectively. In adulthood, ultrasound-based NAFLD, abnormal liver enzymes, and related risk factors were assessed.

RESULTS

Overweight or obese children were more likely to have adult NAFLD (males: odds ratio [OR] = 2.49 for BMI and 2.78 for subscapular skinfold thickness; females: OR = 3.34 and 3.61; all Ps < .001) and alanine aminotransferase (ALT) elevation (males: OR = 1.64 and 1.66; females: OR = 2.12 and 3.01; all Ps < .05) than children with normal weight for both sexes. Compared with subjects who had normal weight in childhood and were nonobese in adulthood, subjects who were obese in adulthood, irrespective of their childhood adiposity status, were more likely to have NAFLD and ALT elevation in adulthood for both sexes. However, subjects who were overweight or obese in childhood but became nonobese in adulthood had similar likelihood of having NAFLD and ALT elevation in adulthood for both sexes.

CONCLUSIONS

Overweight or obese children are more likely to have NAFLD and ALT elevation in adulthood. However, the risk associated with increased weight during childhood can be mitigated by becoming nonobese in adulthood.

Lipid overload during gestation and lactation can independently alter lipid homeostasis in offspring and promote metabolic impairment after new challenge to high-fat diet

Background

Nutritional status in early life is critically involved in the metabolic phenotype of offspring. However the changes triggered by maternal consumption of high-fat diet (HFD) in pre- or postnatal period should be better understood. Here we evaluated whether maternal HFD consumption during gestation and lactation could differently affect liver miR-122 and miR-370 expression leading to metabolic damages observed in offspring. Moreover, we investigate whether early overnutrition program offspring to more harmful response to HFD in later life.

Methods

Female mice were fed either a standard chow (SC) diet or a HFD three weeks before and during mating, gestation and/or lactation. Offspring were evaluated on the delivery day (d0), in a cross-fostering model at day 28 (d28) and in adult life, after a re-challenge with a HFD (d82).

Results

In vitro analysis using liver cell line showed that palmitate could induced decrease in miR-122 and increase in miR-370 expression. Newborn pups (d0) from obese dams showed a decrease in lipid oxidation markers (Cpt1a and Acadvl), an increase in triacylglycerol synthesis markers (Agpat and Gpam), as well as lower miR-122 and higher miR-370 hepatic content that was inversely correlated to maternal serum NEFA and TAG. Pups fostered to SC dams presented an increase in body weight and Agpat/Gpam expression at d28 compared to pups fostered to HFD dams and an inverse correlation was observed between miR-122 hepatic expression and offspring serum TAG. In adult life (d82), the reintroduction of HFD resulted in higher body weight gain and hepatic lipid content. These effects were accompanied by impairment in lipid and glucose metabolism, demonstrated by reduced Cpt1a/Acadvl and increased Agpat/Gpam expression, lower glucose tolerance and insulin sensitivity.

Conclusion

Our data suggest that both gestational and lactation overnutrition results in metabolic changes that can permanently alter lipid homeostasis in offspring. The presence of fatty acids in maternal blood and milk seem to be responsible for modulating the expression of miR-122 and miR-370, which are involved in liver metabolism. These alterations significantly increase susceptibility to obesity and ectopic lipid accumulation and lead to a more harmful response to HFD in offspring.

Electronic supplementary material

The online version of this article (doi:10.1186/s12986-017-0168-4) contains supplementary material, which is available to authorized users.

Lipid overload during gestation and lactation can independently alter lipid homeostasis in offspring and promote metabolic impairment after new challenge to high-fat diet

BACKGROUND

Nutritional status in early life is critically involved in the metabolic phenotype of offspring. However the changes triggered by maternal consumption of high-fat diet (HFD) in pre- or postnatal period should be better understood. Here we evaluated whether maternal HFD consumption during gestation and lactation could differently affect liver miR-122 and miR-370 expression leading to metabolic damages observed in offspring. Moreover, we investigate whether early overnutrition program offspring to more harmful response to HFD in later life.

METHODS

Female mice were fed either a standard chow (SC) diet or a HFD three weeks before and during mating, gestation and/or lactation. Offspring were evaluated on the delivery day (d0), in a cross-fostering model at day 28 (d28) and in adult life, after a re-challenge with a HFD (d82).

RESULTS

In vitro analysis using liver cell line showed that palmitate could induced decrease in miR-122 and increase in miR-370 expression. Newborn pups (d0) from obese dams showed a decrease in lipid oxidation markers (Cpt1a and Acadvl), an increase in triacylglycerol synthesis markers (Agpat and Gpam), as well as lower miR-122 and higher miR-370 hepatic content that was inversely correlated to maternal serum NEFA and TAG. Pups fostered to SC dams presented an increase in body weight and Agpat/Gpam expression at d28 compared to pups fostered to HFD dams and an inverse correlation was observed between miR-122 hepatic expression and offspring serum TAG. In adult life (d82), the reintroduction of HFD resulted in higher body weight gain and hepatic lipid content. These effects were accompanied by impairment in lipid and glucose metabolism, demonstrated by reduced Cpt1a/Acadvl and increased Agpat/Gpam expression, lower glucose tolerance and insulin sensitivity.

CONCLUSION

Our data suggest that both gestational and lactation overnutrition results in metabolic changes that can permanently alter lipid homeostasis in offspring. The presence of fatty acids in maternal blood and milk seem to be responsible for modulating the expression of miR-122 and miR-370, which are involved in liver metabolism. These alterations significantly increase susceptibility to obesity and ectopic lipid accumulation and lead to a more harmful response to HFD in offspring.

Green tea extract treatment reduces NFκB activation in mice with diet-induced nonalcoholic steatohepatitis by lowering TNFR1 and TLR4 expression and ligand availability

NFκB-mediated inflammation contributes to liver injury during nonalcoholic steatohepatitis (NASH). We hypothesized that antiinflammatory activities of green tea extract (GTE) during NASH would lower tumor necrosis factor receptor-1 (TNFR1)- and Toll-like receptor-4 (TLR4)-mediated NFκB activation. Male C57BL6/J mice (6 weeks old) were fed a low-fat (LF) or high-fat (HF) diet for 12 weeks to induce NASH. They were then randomized to continue on these diets supplemented with 0 or 2% GTE (n=10/group) for an additional 8 weeks prior to evaluating NASH, NFκB inflammation and TNFR1 and TLR4 receptor complexes and their respective ligands, TNFα and endotoxin. HF feeding increased (P<.05) serum alanine aminotransferase (ALT) activity and histological evidence of NASH compared with LF controls. HF-mediated increases in NFκB p65 phosphorylation were also accompanied by increased serum TNFα and endotoxin concentrations, mRNA expression of hepatic TNFR1 and TLR4 and MyD88 protein levels. GTE in LF mice had no effect (P>.05) on liver histology or inflammatory responses. However, GTE in HF mice decreased biochemical and histological parameters of NASH and lowered hepatic p65 phosphorylation in association with decreased serum TNFα, mRNA expression of TNFR1 and TLR4 and MyD88 protein. GTE in HF-fed mice also lowered serum endotoxin and up-regulated mRNA expression of duodenal occludin and zonula occluden-1 and ileal occludin and claudin-1 that were otherwise lowered in expression by HF feeding. These data suggest that dietary GTE treatment reduces hepatic inflammation in NASH by decreasing proinflammatory signaling through TNFR1 and TLR4 that otherwise increases NFκB activation and liver injury.

Nonalcoholic Fatty Liver Disease: Epidemiology, Pathogenesis, Natural History, Diagnosis, and Current Treatment Options

Nonalcoholic fatty liver disease (NAFLD) is on the rise and has become a major etiology for chronic liver disease. It is frequently associated with obesity, insulin resistance, hypertension, and dyslipidemia and is considered the hepatic manifestation of metabolic syndrome. In this review, we present a summary of the epidemiology and pathogenesis of NAFLD, and discuss the clinical evaluation and stratification of NAFLD patients into low, intermediate, and high risk with respect to liver-related outcomes. While diet and exercise are the cornerstone of treatment in all patients, the low rate of adherence and inadequacy of these recommendations necessitate pharmacologic intervention, especially in intermediate- and high-risk patients. We discuss vitamin E and pioglitazone which are often used as first-line therapy by many practitioners, with pentoxifylline and liraglutide as backup agents. Several drugs are in advanced-phase clinical trials and will likely change the landscape for management of NAFLD in the very near future.

The Two Faces of Galectin-3: Roles in Various Pathological Conditions

Galectin-3, a unique chimaera-type member of the lectin family, displays a wide range of activities. This versatile molecule is involved in fundamental biological processes, including cell proliferation, cell-cell adhesion, apoptosis and immune responses.

This review is aimed at providing a general overview of the biological actions and diverse effects of Galectin-3 in many pathological conditions, with a specific focus on autoimmunity, inflammation and tumour progression. We report herein that Galectin-3 exerts deleterious functions determined by promotion of tumour progression and liver inflammation or aggravation of T cell-mediated autoimmune diseases. On the other hand, Galectin-3 exhibits a protective role in metabolic abnormalities and primary biliary cirrhosis.

The paradoxical “yin and yang” functions of Galectin-3 depend not only on its tissue and cellular localization but also on its availability, glycosylation status and the expression level of its ligands.

Increased Circulating Levels of Alpha-Ketoglutarate in Morbidly Obese Women with Non-Alcoholic Fatty Liver Disease

Background

Non-alcoholic fatty liver disease (NAFLD) causes a wide spectrum of liver damage, ranging from simple steatosis to cirrhosis. However, simple steatosis (SS) and steatohepatitis (NASH) cannot yet be distinguished by clinical or laboratory features. The aim of this study was to assess the relationship between alpha-ketoglutarate and the degrees of NAFLD in morbidly obese patients.

Materials and Methods

We used a gas chromatography-quadruple time-of-flight-mass spectrometry analysis to quantify alpha-ketoglutarate in serum from normal-weight subjects (n = 30) and morbidly obese women (n = 97) with or without NAFLD.

Results

We found that serum levels of alpha-ketoglutarate were significantly higher in morbidly obese women than in normal-weight women. We showed that circulating levels of alpha-ketoglutarate were lower in lean controls and morbidly obese patients without NAFLD. We also found that alpha-ketoglutarate serum levels were higher in both SS and NASH than in normal liver of morbidly obese patients. However, there was no difference between SS and NASH. Moreover, we observed that circulating levels of alpha-ketoglutarate were associated with glucose metabolism parameters, lipid profile, hepatic enzymes and steatosis degree. In addition, diagnostic performance of alpha-ketoglutarate has been analyzed in NAFLD patients. The AUROC curves from patients with liver steatosis exhibited an acceptable clinical utility. Finally, we showed that the combination of biomarkers (AST, ALT and alpha-ketoglutarate) had the highest accuracy in diagnosing liver steatosis.

Conclusion

These findings suggest that alpha-ketoglutarate can determine the presence of non-alcoholic fatty liver in morbidly obese patients but it is not valid a biomarker for NASH.

Astaxanthin inhibits inflammation and fibrosis in the liver and adipose tissue of mouse models of diet-induced obesity and nonalcoholic steatohepatitis

The objective of this study was to determine if astaxanthin (ASTX), a xanthophyll carotenoid, can prevent obesity-associated metabolic abnormalities, inflammation and fibrosis in diet-induced obesity (DIO) and nonalcoholic steatohepatitis (NASH) mouse models. Male C57BL/6J mice were fed a low-fat (6% fat, w/w), a high-fat/high-sucrose control (HF/HS; 35% fat, 35% sucrose, w/w), or a HF/HS containing ASTX (AHF/HS; 0.03% ASTX, w/w) for 30 weeks. To induce NASH, another set of mice was fed a HF/HS diet containing 2% cholesterol (HF/HS/HC) a HF/HS/HC with 0.015% ASTX (AHF/HS/HC) for 18 weeks. Compared to LF, HF/HS significantly increased plasma total cholesterol, triglyceride and glucose, which were lowered by ASTX. ASTX decreased hepatic mRNA levels of markers of macrophages and fibrosis in both models. The effect of ASTX was more prominent in NASH than DIO mice. In epididymal fat, ASTX also decreased macrophage infiltration and M1 macrophage marker expression, and inhibited hypoxia-inducible factor 1-α and its downstream fibrogenic genes in both mouse models. ASTX significantly decreased tumor necrosis factor α mRNA in the splenocytes from DIO mice upon lipopolysaccharides stimulation compared with those from control mice fed an HF/HS diet. Additionally, ASTX significantly elevated the levels of genes that regulate fatty acid β-oxidation and mitochondrial biogenesis in the skeletal muscle compared with control obese mice, whereas no differences were noted in adipose lipogenic genes. Our results indicate that ASTX inhibits inflammation and fibrosis in the liver and adipose tissue and enhances the skeletal muscle's capacity for mitochondrial fatty acid oxidation in obese mice.

Influence of the rs738409 polymorphism in patatin-like phospholipase 3 on the treatment efficacy of non-alcoholic fatty liver disease with type 2 diabetes mellitus

AIM

A genome-wide association study revealed that the single nucleotide polymorphism (SNP) rs738409 in the patatin-like phospholipase 3 gene (PNPLA3) was strongly associated with non-alcoholic fatty liver disease (NAFLD). Recent pilot studies investigated the effects of dipeptidyl peptidase-4 inhibitors on liver function and glucose metabolism in NAFLD with type 2 diabetes mellitus (DM). We herein evaluated the efficacy of alogliptin in NAFLD patients with type 2 DM as well as the relationship between genotypes at rs738409 in PNPLA3 and treatment efficacy.

METHODS

Forty-one biopsy-proven NAFLD patients with type 2 DM treated with 25 mg/day alogliptin were retrospectively enrolled. SNP rs738409 in PNPLA3 was present in all patients. Clinical data were measured before and after the treatment.

RESULTS

Average hemoglobin A1c (HbA1c) levels mostly remained unchanged. Moreover, significant changes were not noted in the levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) during the follow-up period. A positive correlation was observed between improvements in HbA1c (ΔHbA1c) levels and changes in AST (ΔAST) and ALT (ΔALT) levels (r = 0.325 and 0.439, respectively). Patients with the risk allele (G-allele) showed more positive correlation between ΔHbA1c and changes in transaminase. Furthermore, improvements in the levels of total cholesterol, triglycerides and hyaluronic acid were significantly greater in G-allele patients in the weight loss group.

CONCLUSION

The treatment of NAFLD with type 2 DM with alogliptin contributed to the amelioration of NAFLD. Our results suggested that differences in the PNPLA3 risk allele affected the therapeutic effects of this treatment.

Green tea extract provides extensive Nrf2-independent protection against lipid accumulation and NFκB pro- inflammatory responses during nonalcoholic steatohepatitis in mice fed a high-fat diet

SCOPE

Green tea extract (GTE) reduces liver steatosis and inflammation during nonalcoholic steatohepatitis (NASH). We hypothesized GTE would mitigate NASH in a nuclear factor erythroid-2-related-factor-2 (Nrf2)-dependent manner in a high fat (HF) induced model.

METHODS AND RESULTS

Nrf2-null and wild-type (WT) mice were fed an HF diet containing 0 or 2% GTE for eight weeks prior to assessing parameters of NASH. Compared to WT mice, Nrf2-null mice had increased serum alanine aminotransferase, hepatic triglyceride, expression of free fatty acid uptake and lipogenic genes, malondialdehyde and NFκB phosphorylation and expression of pro-inflammatory genes. In WT mice, GTE increased Nrf2 and NADPH:quinone oxidoreductase-1 mRNA, and lowered hepatic steatosis, lipid uptake and lipogenic gene expression, malondialdehyde, and NFκB-dependent inflammation. In Nrf2-null mice, GTE lowered NFκB phosphorylation and TNF-α and MCP1 mRNA to levels observed in WT mice fed GTE whereas hepatic triglyceride and lipogenic genes were lowered only to those of WT mice fed no GTE. Malondialdehyde was lowered in Nrf2-null mice fed GTE, but not to levels of WT mice, and without improving the hepatic antioxidants α-tocopherol, ascorbic acid and uric acid.

CONCLUSION

Nrf2 deficiency exacerbates NASH whereas anti-inflammatory and hypolipidemic activities of GTE likely occur largely independent of Nrf2 signaling.

Diet-induced dyslipidemia leads to nonalcoholic fatty liver disease and oxidative stress in guinea pigs

Chronic dyslipidemia imposed by a high-fat and high-caloric dietary regime leads to debilitating disorders such as obesity, nonalcoholic fatty liver disease (NAFLD), and insulin resistance. As disease rates surge, so does the need for high validity animal models to effectively study the causal relationship between diet and disease progression. The dyslipidemic guinea pig displays a high similarity with the human lipoprotein profile and may in this aspect be superior to other rodent models. This study investigated the effects of 2 long-term Westernized diets (0.35% cholesterol, 18.5% vegetable oil and either 15% or 20% sucrose) compared with isocaloric standard chow in adult guinea pigs. Biochemical markers confirmed dyslipidemia in agreement with dietary regimens; however, both high-fat groups displayed a decreased tissue fat percentage compared with controls. Macroscopic appearance, histopathologic evaluation, and plasma markers of liver function confirmed NAFLD in high-fat groups, supported by liver redox imbalance and markers suggesting hepatic endothelial dysfunction. Plasma markers indicated endothelial dysfunction in response to a high-fat diet, although atherosclerotic lesions were not evident. Evaluation of glucose tolerance showed no indication of insulin resistance. The 5% increase in sucrose between the 2 high-fat diets did not lead to significant differences between groups. In conclusion, we find the dyslipidemic guinea pig to be a valid model of diet imposed dyslipidemia, particularly with regards to hepatic steatosis and endothelial dysfunction. Furthermore, the absence of obesity supports the present study setup as targeting NAFLD in nonobese individuals.

Improvements of Glucose and Lipid Metabolism After Jejuno-ileal Circuit Procedure in a Non-obese Diabetic Rat Model

BACKGROUND

In a recent study, we showed a jejuno-ileal circuit (JIC) procedure that effectively improved glucose homeostasis, but the intrinsic mechanism requires further studies. Furthermore, the role of JIC in lipid metabolism is also unknown. Given that adiposity aggravates insulin sensitivity, we hypothesize that the JIC procedure improves fat metabolism and thus further contributes to diabetic remission. The aim of this study was to investigate the effects of JIC surgery on lipid metabolism and glucose homeostasis in a non-obese diabetic rat model.

METHODS

Fourteen high-fat diet and low-dose streptozotocin-induced diabetic rats were randomly divided into JIC and sham-JIC groups. Body weight, food intake, glucose tolerance, insulin resistance, serum lipid parameters, glucagon-like peptide 1 (GLP-1), and adipose-derived hormones were measured. At 12 weeks postoperatively, the expressions of hepatic fatty acid synthase (FAS) and acetyl-CoA carboxylase (ACC) were measured by Western blot. The lipid content of liver was assessed by hematoxylin-eosin staining and Oil Red O staining. The enteroendocrine cells in the distal ileum were examined by immunohistochemical staining.

RESULTS

Relative to the sham group, the JIC rats exhibited significant improvements in glucose tolerance, insulin resistance, and dyslipidemia without weight loss, showing increased GLP-1 and adiponectin and decreased leptin. JIC also reduced the expression of FAS and ACC in the liver, exhibited improved hepatic fat content, and raised the levels of GLP-1 and chromogranin A in the distal gut.

CONCLUSIONS

JIC alleviated lipometabolic disorders in hyperglycemic rats, which may contribute to the amelioration of insulin sensitivity and glycemic control.

Research advances in the relationship between nonalcoholic fatty liver disease and atherosclerosis

Nonalcoholic fatty liver disease (NAFLD) is a metabolic stress-induced liver disease that is closely related not only to genetic susceptibility but also to insulin resistance and highly linked with metabolic syndrome. In recent years, the prevalence of NAFLD has increased rapidly, paralleling the epidemic of type 2 diabetes mellitus and obesity leading to cardiovascular disease. It has been demonstrated that NAFLD is highly associated with atherosclerosis. With recently gained knowledge, it appears that NAFLD may induce insulin resistance, dyslipidemia, oxidative stress, inflammation, and fluctuation of adipokines associated with atherosclerosis. In this review, we aimed to summarize recent discoveries related to both NAFLD and atherosclerosis, and to identify possible mechanisms linking them.

The Prevalence of Non-Alcoholic Fatty Liver Disease in Children and Adolescents: A Systematic Review and Meta-Analysis

Background & Aims

Narrative reviews of paediatric NAFLD quote prevalences in the general population that range from 9% to 37%; however, no systematic review of the prevalence of NAFLD in children/adolescents has been conducted. We aimed to estimate prevalence of non-alcoholic fatty liver disease (NAFLD) in young people and to determine whether this varies by BMI category, gender, age, diagnostic method, geographical region and study sample size.

Methods

We conducted a systematic review and meta-analysis of all studies reporting a prevalence of NAFLD based on any diagnostic method in participants 1–19 years old, regardless of whether assessing NAFLD prevalence was the main aim of the study.

Results

The pooled mean prevalence of NAFLD in children from general population studies was 7.6% (95%CI: 5.5% to 10.3%) and 34.2% (95% CI: 27.8% to 41.2%) in studies based on child obesity clinics. In both populations there was marked heterogeneity between studies (I² = 98%). There was evidence that prevalence was generally higher in males compared with females and increased incrementally with greater BMI. There was evidence for differences between regions in clinical population studies, with estimated prevalence being highest in Asia. There was no evidence that prevalence changed over time. Prevalence estimates in studies of children/adolescents attending obesity clinics and in obese children/adolescents from the general population were substantially lower when elevated alanine aminotransferase (ALT) was used to assess NAFLD compared with biopsies, ultrasound scan (USS) or magnetic resonance imaging (MRI).

Conclusions

Our review suggests the prevalence of NAFLD in young people is high, particularly in those who are obese and in males.

Folic acid supplementation during high-fat diet feeding restores AMPK activation via an AMP-LKB1-dependent mechanism

AMPK is an endogenous energy sensor that regulates lipid and carbohydrate metabolism. Nonalcoholic fatty liver disease (NAFLD) is regarded as a hepatic manifestation of metabolic syndrome with impaired lipid and glucose metabolism and increased oxidative stress. Our recent study showed that folic acid supplementation attenuated hepatic oxidative stress and lipid accumulation in high-fat diet-fed mice. The aim of the present study was to investigate the effect of folic acid on hepatic AMPK during high-fat diet feeding and the mechanisms involved. Male C57BL/6J mice were fed a control diet (10% kcal fat), a high-fat diet (60% kcal fat), or a high-fat diet supplemented with folic acid (26 mg/kg diet) for 5 wk. Mice fed a high-fat diet exhibited hyperglycemia, hepatic cholesterol accumulation, and reduced hepatic AMPK phosphorylation. Folic acid supplementation restored AMPK phosphorylation (activation) and reduced blood glucose and hepatic cholesterol levels. Activation of AMPK by folic acid was mediated through an elevation of its allosteric activator AMP and activation of its upstream kinase, namely, liver kinase B1 (LKB1) in the liver. Consistent with in vivo findings, 5-methyltetrahydrofolate (bioactive form of folate) restored phosphorylation (activation) of both AMPK and LKB1 in palmitic acid-treated HepG2 cells. Activation of AMPK by folic acid might be responsible for AMPK-dependent phosphorylation of HMG-CoA reductase, leading to reduced hepatic cholesterol synthesis during high-fat diet feeding. These results suggest that folic acid supplementation may improve cholesterol and glucose metabolism by restoration of AMPK activation in the liver.

Accuracy of computer-aided ultrasound as compared with magnetic resonance imaging in the evaluation of nonalcoholic fatty liver disease in obese and eutrophic adolescents

OBJECTIVE

To compare the accuracy of computer-aided ultrasound (US) and magnetic resonance imaging (MRI) by means of hepatorenal gradient analysis in the evaluation of nonalcoholic fatty liver disease (NAFLD) in adolescents.

MATERIALS AND METHODS

This prospective, cross-sectional study evaluated 50 adolescents (aged 11-17 years), including 24 obese and 26 eutrophic individuals. All adolescents underwent computer-aided US, MRI, laboratory tests, and anthropometric evaluation. Sensitivity, specificity, positive and negative predictive values and accuracy were evaluated for both imaging methods, with subsequent generation of the receiver operating characteristic (ROC) curve and calculation of the area under the ROC curve to determine the most appropriate cutoff point for the hepatorenal gradient in order to predict the degree of steatosis, utilizing MRI results as the gold-standard.

RESULTS

The obese group included 29.2% girls and 70.8% boys, and the eutrophic group, 69.2% girls and 30.8% boys. The prevalence of NAFLD corresponded to 19.2% for the eutrophic group and 83% for the obese group. The ROC curve generated for the hepatorenal gradient with a cutoff point of 13 presented 100% sensitivity and 100% specificity. As the same cutoff point was considered for the eutrophic group, false-positive results were observed in 9.5% of cases (90.5% specificity) and false-negative results in 0% (100% sensitivity).

CONCLUSION

Computer-aided US with hepatorenal gradient calculation is a simple and noninvasive technique for semiquantitative evaluation of hepatic echogenicity and could be useful in the follow-up of adolescents with NAFLD, population screening for this disease as well as for clinical studies.

Volume-dependent effect of supervised exercise training on fatty liver and visceral adiposity index in subjects with type 2 diabetes The Italian Diabetes Exercise Study (IDES)

AIMS

This study evaluated the effect of supervised exercise training on liver enzymes and two surrogate measures of non-alcoholic fatty liver disease (NAFLD) in subjects with type 2 diabetes.

METHODS

Sedentary patients from 22 outpatient diabetes clinics were randomized by center, age and treatment to twice-a-week supervised aerobic and resistance training plus structured exercise counseling (exercise group, EXE; n=303) versus counseling alone (control group, CON; n=303) for 12 months. EXE participants were further randomized to low-to-moderate (n=142) or moderate-to-high (n=161) intensity training of equal energy cost. Baseline and end-of-study levels of liver enzymes, fatty liver index (FLI) and visceral adiposity index (VAI) were obtained.

RESULTS

Enzyme levels did not change, whereas FLI and VAI decreased significantly in EXE, but not CON participants. Physical activity (PA) volume was an independent predictor of both FLI and VAI reductions, the extent of which increased from the 1st to the 4th quintile of PA volume and baseline to end-of-study changes in fitness parameters. Differences in the effect of LI versus HI training were negligible.

CONCLUSIONS

Data from this large cohort of subjects with type 2 diabetes indicate that FLI and VAI decrease with supervised training in a volume-dependent manner.

Efficacy of the Omega-3 Index in predicting non-alcoholic fatty liver disease in overweight and obese adults: a pilot study

Non-alcoholic fatty liver disease (NAFLD) is an independent predictor of CVD in otherwise healthy individuals. Low n-3 PUFA intake has been associated with the presence of NAFLD; however, the relationship between a biomarker of n-3 status – the Omega-3 Index – and liver fat is yet to be elucidated. A total of eighty overweight adults (fifty-six men) completed the anthropometric and biochemical measurements, including the Omega-3 Index, and underwent proton magnetic resonance spectroscopy assessment of liver fat. Bivariate correlations and multiple regression analyses were performed with reference to prediction of liver fat percentage. The mean Omega-3 Index was high in both NAFLD (intrahepatic lipid concentration≥5·5 %) and non-NAFLD groups. The Omega-3 Index, BMI, waist circumference, glucose, insulin, TAG, high-sensitive C-reactive protein (hsCRP) and alanine aminotransferase (ALT) were positively correlated, and HDL and erythrocyte n-6:n-3 ratio negatively correlated with liver fat concentration. Regression analysis found that simple anthropometric and demographic variables (waist, age) accounted for 31 % of the variance in liver fat and the addition of traditional cardiometabolic blood markers (TAG, HDL, hsCRP and ALT) increased the predictive power to 43 %. The addition of the novel erythrocyte fatty acid variable (Omega-3 Index) to the model only accounted for a further 3 % of the variance (P=0·049). In conclusion, the Omega-3 Index was associated with liver fat concentration but did not improve the overall capacity of demographic, anthropometric and blood markers to predict NAFLD.

Role of fish oil in human health and possible mechanism to reduce the inflammation

The roles of Omega-3 FAs are inflammation antagonists, while Omega-6 FAs are precursors for inflammation. The plant form of Omega-3 FAs is the short-chain α-linolenic acid, and the marine forms are the long-chain fatty acids: docosahexaenoic acid and eicosapentaenoic acid. Omega-3 FAs have unlimited usages, and they are considered as omnipotent since they may benefit heart health, improve brain function, reduce cancer risks and improve people's moods. Omega-3 FAs also have several important biological effects on a range of cellular functions that may decrease the onset of heart diseases and reduce mortality among patients with coronary heart disease, possibly by stabilizing the heart's rhythm and by reducing blood clotting. Some review studies have described the beneficial roles of Omega-3 FAs in cardiovascular diseases (CVDs), cancer, diabetes, and other conditions, including inflammation. Studies of the effect of Omega-3 FAs gathered from studies in diseased and healthy population. CVDs including atherosclerosis, coronary heart diseases, hypertension, and metabolic syndrome were the major fields of investigation. In studies of obesity, as the central obesity increased, the level of adipocyte synthesis of pro-inflammatory cytokines like tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6) were increased and the level of anti-inflammatory adiponectin was decreased indicating a state of inflammation. The level of C reactive protein (CRP) synthesized from hepatocyte is increased by the influence of IL-6. CRP can be considered as a marker of systemic inflammation associated with increased risks of CVDs. In molecular studies, Omega-3 FAs have direct effects on reducing the inflammatory state by reducing IL-6, TNF-α, CRP and many other factors. While the appropriate dosage along with the administrative duration is not known, the scientific evidence-based recommendations for daily intake are not modified.

Are microRNAs the Molecular Link Between Metabolic Syndrome and Alzheimer's Disease?

Alzheimer's disease (AD) is the most common cause of dementia in people over 65 years of age. At present, treatment options for AD address only its symptoms, and there are no available treatments for the prevention or delay of the disease process. Several preclinical and epidemiological studies have linked metabolic risk factors such as hypertension, obesity, dyslipidemia, and diabetes to the pathogenesis of AD. However, the molecular mechanisms that underlie this relationship are not fully understood. Considering that less than 1% of cases of AD are attributable to genetic factors, the identification of new molecular targets linking metabolic risk factors to neuropathological processes is necessary for improving the diagnosis and treatment of AD. The dysregulation of microRNAs (miRNAs), small non-coding RNAs that regulate several biological processes, has been implicated in the development of different pathologies. In this review, we summarize some of the relevant evidence that points to the role of miRNAs in metabolic syndrome (MetS) and AD and propose that miRNAs may be a molecular link in the complex relationship between both diseases.

Increased levels of systolic blood pressure within the normal range are associated with significantly elevated risks of nonalcoholic fatty liver disease

A positive association between hypertension or high-normal blood pressure (BP) and risk of nonalcoholic fatty liver disease (NAFLD) is well-known; however, no data have been generated exploring the risk of NAFLD within the normal range of BP. We aimed to assess the association between normal systolic blood pressure (SBP) and risk of NAFLD.A total of 27,769 subjects from 2 separate medical centers were included. Subjects were divided into 4 groups (G1 to G4) by SBP levels: G1: 90-99 mmHg, G2: 100-109 mmHg, G3: 110-119 mmHg, and G4: 120-129 mmHg. The prevalence, hazard ratios (HRs) and 95% confidence intervals (CIs) for NAFLD were calculated across each group, using the G1 as reference.Higher SBP was observed in subjects with NAFLD than those without NAFLD. The prevalence of NAFLD in a cross-sectional population from G1 to G4 was 6.1%, 13.6%, 19.6%, and 25.8%, respectively. The HRs for NAFLD in the longitudinal population were 2.17 (95% CI 1.60-2.93), 3.87 (95% CI 2.89-5.16), 5.81 (95% CI 4.32-7.81) for G2, G3, and G4, respectively. After adjusting for known confounding variables, HRs of G2 to G4 were 1.44 (95% CI 1.06-1.96), 1.94 (95% CI 1.44-2.61), 2.38 (95% CI 1.75-3.23), respectively.This is the first study to demonstrate that increased levels of SBP within the normal range are associated with significantly elevated risks of NAFLD, independent of other confounding factors.

Ursolic acid inhibits the development of nonalcoholic fatty liver disease by attenuating endoplasmic reticulum stress

Ursolic acid (UA) is a natural pentacyclic triterpenoid compound, which is enriched with many herbs and plants, such as apple, cranberry and olive. UA performs multiple biological activities including anti-oxidation, anti-inflammation, anti-cancer and hepatoprotection. However, the exact mechanism underlying the hepatoprotective activity of UA remains unclear. In this study, the effects of UA on the development of nonalcoholic fatty liver disease (NAFLD) were investigated. In vivo, UA treatment (0.14%, w/w) significantly decreased the liver weight, serum levels of ALT/AST and hepatic steatosis in db/db mice (a type 2 diabetic mouse model). In vitro, UA treatment (10-30 μg ml(-1)) significantly decreased palmitic acid induced intracellular lipid accumulation in L02 cells. Our results suggested that the beneficial effects of UA on NAFLD may be due to its ability to increase lipid β-oxidation and to inhibit the hepatic endoplasmic reticulum (ER) stress. Together, UA may be further considered as a natural compound for NAFLD treatment.

Altered fatty acid metabolism-related gene expression in liver from morbidly obese women with non-alcoholic fatty liver disease

Lipid accumulation in the human liver seems to be a crucial mechanism in the pathogenesis and the progression of non-alcoholic fatty liver disease (NAFLD). We aimed to evaluate gene expression of different fatty acid (FA) metabolism-related genes in morbidly obese (MO) women with NAFLD. Liver expression of key genes related to de novo FA synthesis (LXRα, SREBP1c, ACC1, FAS), FA uptake and transport (PPARγ, CD36, FABP4), FA oxidation (PPARα), and inflammation (IL6, TNFα, CRP, PPARδ) were assessed by RT-qPCR in 127 MO women with normal liver histology (NL, n = 13), simple steatosis (SS, n = 47) and non-alcoholic steatohepatitis (NASH, n = 67). Liver FAS mRNA expression was significantly higher in MO NAFLD women with both SS and NASH compared to those with NL (p = 0.003, p = 0.010, respectively). Hepatic IL6 and TNFα mRNA expression was higher in NASH than in SS subjects (p = 0.033, p = 0.050, respectively). Interestingly, LXRα, ACC1 and FAS expression had an inverse relation with the grade of steatosis. These results were confirmed by western blot analysis. In conclusion, our results indicate that lipogenesis seems to be downregulated in advanced stages of SS, suggesting that, in this type of extreme obesity, the deregulation of the lipogenic pathway might be associated with the severity of steatosis.

Green Tea Lowers Hepatic COX-2 and Prostaglandin E2 in Rats with Dietary Fat-Induced Nonalcoholic Steatohepatitis

Green tea extract (GTE) protects against nonalcoholic steatohepatitis (NASH) by decreasing hepatic steatosis and nuclear factor kappa B (NFκB) activation. We hypothesized that hypolipidemic and anti-inflammatory activities of GTE would protect against NASH by reducing cyclooxygenase-2 (COX-2), an NFκB-dependent enzyme, and prostaglandin E2 (PGE2) in a dietary fat-induced obese model. Male Wistar rats were fed a low-fat diet containing no GTE or a high-fat (HF) diet containing GTE at 0%, 1%, or 2% for 8 weeks. Insulin resistance and total hepatic fatty acids increased following HF feeding (P<.05) and these were normalized by GTE at 1-2%. GTE (1-2%) normalized hepatic malondialdehyde without affecting cytochrome P450 2E1 mRNA expression, which was otherwise increased by HF feeding. HF-mediated increases in hepatic COX-2 protein and activity as well as PGE2 concentrations were normalized by GTE (1-2%). COX-2 activity and PGE2 were correlated to each other, and to serum alanine aminotransferase (ALT) and hepatic NFκB-binding activity (P<.05; r=0.28-0.49). GTE attenuated HF-mediated increases in total hepatic n-6 and n-3, without affecting the n-6/n-3 ratio. GTE did not affect HF-mediated increases in n-6 in nonesterified fatty acid (NEFA) and phospholipid pools, whereas n-3 and n-6/n-3 in both pools were unaffected by GTE and HF feeding. GTE decreased total hepatic arachidonic acid without affecting HF-mediated increases in arachidonic acid in NEFA or phospholipid pools. Thus, GTE attenuates lipid peroxidation and PGE2 accumulation by decreasing COX-2 activity independent of arachidonic acid availability and supports an additional mechanism by which GTE protects against liver injury during NASH in an HF-feeding model.

Are women with polycystic ovarian syndrome at a high risk of non-alcoholic Fatty liver disease; a meta-analysis

CONTEXT

Insulin resistance is a hallmark of metabolic syndrome (MS). It has been proposed that both polycystic ovarian syndrome (PCOS) and nonalcoholic fatty liver disease (NAFLD) are correlated with Insulin resistance. Therefore, PCOS and NAFLD can be attributed with insulin resistance and therefore MS. The aim of this meta-analysis was to determine whether PCOS patients are at a high risk of NAFLD.

EVIDENCE ACQUISITION

Google scholar, Scopus, ISI Web of Science, Embase, MEDLINE, and some Iranian databases such as scientific information database (SID), IranMedex, and MagIran were searched to identify relevant studies. We included all papers regardless of their language from January 1985 to June 2013. By using data on prevalence of NAFLD in patients with and without PCOS, odds ratio (OR) with 95% confidence intervals (CIs) were calculated in each study. Chi-squared test was used to assess heterogeneity between studies.

RESULTS

We finally included seven eligible studies. According to chi-squared test, there was a significant heterogeneity (73.6%) between studies (P = 0.001). NAFLD prevalence was significantly higher in patients with PCOS compared to healthy control, with an overall OR of 3.93 (95% CI: 2.17, 7.11).There was no significant publication bias based on Begg's and Egger's tests.

CONCLUSIONS

According to the results of this meta-analysis, there was a high risk of NAFLD in women with PCOS. We suggest evaluating patients with PCOS regarding NAFLD.

Type 2 diabetes mellitus is associated with the fibrosis severity in patients with nonalcoholic fatty liver disease in a large retrospective cohort of Japanese patients

BACKGROUND

The prevalence of nonalcoholic fatty liver disease (NAFLD) and metabolic syndrome have been increasing worldwide. The associations between metabolic factors and the histologic severity of NAFLD have not yet been clarified. Therefore, we studied the relationships between relevant metabolic factors and the histological severity of NAFLD.

METHODS

In a cross-sectional multicenter study conducted in Japan, we examined 1,365 biopsy-proven NAFLD patients. The frequencies of underlying lifestyle-related diseases and their relationships to the NAFLD histology were investigated.

RESULTS

The hepatic fibrosis stages (Stage 0/1/2/3/4) were 22.6/34.1/26.7/14.5/2.1 (%) in the male patients, and 16.2/31.7/23.9/21.6/6.6 (%) in the female patients. Dyslipidemia was present in 65.7% (hypertriglyceridemia, 45.3%; increased low-density lipoprotein cholesterol, 37.5%; decreased high density lipoprotein cholesterol, 19.5%) of patients. Hypertension was present in 30.2%, and diabetes mellitus (DM) in 47.3%. The fibrosis stage increased with age, especially in postmenopausal females. The body mass index was positively correlated with the fibrosis stage. Deterioration of glucose control was positively correlated with the fibrosis stage, this correlation being more prominent in females. Multivariate analysis identified age and DM as significant risk factors for advanced fibrosis. No significant correlation of the fibrosis stage was observed with hypertension. There was a negative correlation between the serum triglyceride levels and the fibrosis stage.

CONCLUSIONS

DM appeared to be a significant risk factor for advanced fibrosis in patients with NAFLD, and would therefore need to be properly managed to prevent the progression of NAFLD.

Galectin-3: an emerging all-out player in metabolic disorders and their complications

Galectin-3 has been increasingly recognized as an important modulator of several biological functions, by interacting with several molecules inside and outside the cell, and an emerging player in numerous disease conditions. Galectin-3 exerts various and sometimes contrasting effects according to its location, type of injury or site of damage. Strong evidence indicates that galectin-3 participates in the pathogenesis of diabetic complications via its receptor function for advanced glycation end-products (AGEs) and advanced lipoxidation end-products (ALEs). AGEs/ALEs are produced to an increased extent in target organs of complications, such as kidney and vessels; here, lack of galectin-3 impairs their removal, leading to accelerated damage. In contrast, in the liver, AGE/ALE tissue content and injury are decreased, because lack of galectin-3 results in reduced uptake and tissue accumulation of these by-products. Some of these effects can be explained by changes in the expression of receptor for AGEs (RAGE), associated with galectin-3 deletion and consequent changes in AGE/ALE tissue levels. Furthermore, galectin-3 might exert AGE/ALE- and RAGE-independent effects, favoring resolution of inflammation and modulating fibrogenesis and ectopic osteogenesis. These effects are mediated by intracellular and extracellular galectin-3, the latter via interaction with N-glycans at the cell surface to form lattice structures. Recently, galectin-3 has been implicated in the development of metabolic disorders because it favors glucose homeostasis and prevents the deleterious activation of adaptive and innate immune response to obesogenic/diabetogenic stimuli. In conclusion, galectin-3 is an emerging all-out player in metabolic disorders and their complications that deserves further investigation as the potential target of therapeutic intervention.

A new method for measuring the speed of sound in rat liver ex vivo using an ultrasound system: correlation of sound speed with fat deposition

The speed of sound correlates well with the fat content of the liver. Therefore, non-invasive quantification of sound speed in the liver might be of diagnostic value. Here we describe a new non-invasive method that would be clinically applicable for measurement of sound speed in the liver. Sprague-Dawley rats were divided into two groups: a control group and a fatty liver group prepared by keeping the rats on a choline-deficient diet for 6 wk. The livers were subjected to pathologic and biochemical analysis; the speed of sound through the liver tissue was measured using our proposed method and a pulser-receiver as standard. Our results indicated that use of the proposed method makes it feasible to diagnose fatty liver with good accuracy on the basis of sound speed. This approach would have considerable potential for non-invasive diagnosis of fatty liver and would be a valuable adjunct to conventional liver diagnostic procedures.

Glucagon-like peptide-1 analogue, liraglutide, improves liver fibrosis markers in obese women with polycystic ovary syndrome and nonalcoholic fatty liver disease

INTRODUCTION

Nonalcoholic fatty liver disease (NAFLD) has been linked to polycystic ovary syndrome (PCOS) and carries an increased risk of liver cirrhosis. Procollagen type 3 amino-terminal peptide (PIIINP) is an independent predictor of liver cirrhosis.

OBJECTIVE

To assess whether 6-month treatment with GLP-1 analogue, liraglutide, improves markers of liver fibrosis.

DESIGN

A case-control study comparing women with PCOS to age- and weight-matched controls. PCOS was diagnosed according to the Rotterdam criteria. All participants underwent liver function tests and liver ultrasound scan to assess for fatty infiltration. Serum marker for liver fibrosis, PIIINP, was measured at baseline and after 6-month treatment with liraglutide 1·8 mg od.

RESULTS

Nineteen women with PCOS and 17 controls were recruited, age 32·8 ± 7·2 vs 33·5 ± 6·7 years and weight 100·9 ± 16·7 vs 99·3 ± 14·7 kg, respectively. At baseline, the PCOS group had higher testosterone 1·2 ± 0·3 vs 0·9 ± 0·3 nm (P = 0·01), HOMA-IR 5·1 ± 2·6 vs 3·5 ± 1·3 (P = 0·03), AST 22·4 ± 5·2 vs 18·8 ± 3·4 u/l (P = 0·04), PIIINP 4·4 ± 0·8 vs 3·5 ± 0·8 ug/ml (P = 0·01) and NAFLD seven (35%) vs none (P = 0·005), respectively. Twenty-five (69%) participants completed the study (13 PCOS, 12 controls). Following treatment, weight was reduced by 3·0 ± 4·2 kg (P = 0·01) and 3·8 ± 3·4 kg (P = 0·001), respectively. Similarly, HOMA-IR, hsCRP, triglycerides and urinary isoprostane significantly reduced in both groups. PIIINP significantly reduced the in PCOS group 4·4 ± 0·8 vs 3·7 ± 0·9 ug/ml (P < 0·01), but not in controls 3·5 ± 0·8 vs 3·2 ± 0·7 ug/ml (P = 0·08).

CONCLUSIONS

Treatment with liraglutide, and/or associated weight loss, significantly reduced PIIINP levels in obese women with PCOS. This may be an additional beneficial factor when considering the use of liraglutide in women with PCOS, obesity and NAFLD.

Reduced dietary omega-6 to omega-3 fatty acid ratio and 12/15-lipoxygenase deficiency are protective against chronic high fat diet-induced steatohepatitis

Obesity is associated with metabolic perturbations including liver and adipose tissue inflammation, insulin resistance, and type 2 diabetes. Omega-6 fatty acids (ω6) promote and omega-3 fatty acids (ω3) reduce inflammation as they can be metabolized to pro- and anti-inflammatory eicosanoids, respectively. 12/15-lipoxygenase (12/15-LO) enzymatically produces some of these metabolites and is induced by high fat (HF) diet. We investigated the effects of altering dietary ω6/ω3 ratio and 12/15-LO deficiency on HF diet-induced tissue inflammation and insulin resistance. We examined how these conditions affect circulating concentrations of oxidized metabolites of ω6 arachidonic and linoleic acids and innate and adaptive immune system activity in the liver. For 15 weeks, wild-type (WT) mice were fed either a soybean oil-enriched HF diet with high dietary ω6/ω3 ratio (11∶1, HFH), similar to Western-style diet, or a fat Kcal-matched, fish oil-enriched HF diet with a low dietary ω6/ω3 ratio of 2.7∶1 (HFL). Importantly, the total saturated, monounsaturated and polyunsaturated fat content was matched in the two HF diets, which is unlike most published fish oil studies in mice. Despite modestly increased food intake, WT mice fed HFL were protected from HFH-diet induced steatohepatitis, evidenced by decreased hepatic mRNA expression of pro-inflammatory genes and genes involved in lymphocyte homing, and reduced deposition of hepatic triglyceride. Furthermore, oxidized metabolites of ω6 arachidonic acid were decreased in the plasma of WT HFL compared to WT HFH-fed mice. 12/15-LO knockout (KO) mice were also protected from HFH-induced fatty liver and elevated mRNA markers of inflammation and lymphocyte homing. 12/15-LOKO mice were protected from HFH-induced insulin resistance but reducing dietary ω6/ω3 ratio in WT mice did not ameliorate insulin resistance or adipose tissue inflammation. In conclusion, lowering dietary ω6/ω3 ratio in HF diet significantly reduces steatohepatitis.

Postnatal overfeeding promotes early onset and exaggeration of high-fat diet-induced nonalcoholic fatty liver disease through disordered hepatic lipid metabolism in rats

Exposure to overnutrition in critical or sensitive developmental periods may increase the risk of developing obesity and metabolic syndrome in adults. Nonalcoholic fatty liver disease (NAFLD) is the hepatic manifestation of the metabolic syndrome, but the relationship among postnatal nutrition, lipid metabolism, and NAFLD progression during development remains poorly understood. Here we investigated in a rat model whether postnatal overfeeding increases susceptibility to NAFLD in response to a high-fat diet. Litters from Sprague-Dawley dams were culled to three (small litters) or ten (normal litters) pups and then weaned onto a standard or high-fat diet at postnatal day 21 to generate normal-litter, small-litter, normal-litter/high-fat, and small-litter/high-fat groups. At age 16 weeks, the small-litter and both high-fat groups showed obesity, dyslipidemia, and insulin resistance. Hepatic disorders appeared earlier in the small-litter/high-fat rats with greater liver mass gain and higher hepatic triglycerides and steatosis score versus normal-litter/high-fat rats. Hepatic acetyl-CoA carboxylase activity and mRNA expression were increased in small-litter rats and aggravated in small-litter/high-fat rats but not in normal-litter/high-fat rats. The high expression in small-litter/high-fat rats coincided with high sterol regulatory element-binding protein-1c mRNA and protein expression. However, mRNA expression of enzymes involved in hepatic fatty acid oxidation (carnitine palmitoyltransferase 1) and output (microsomal triglyceride transfer protein) was decreased under a high-fat diet regardless of litter size. In conclusion, overfeeding related to small-litter rearing during lactation contributes to the NAFLD phenotype when combined with a high-fat diet, possibly through up-regulated hepatic lipogenesis.

Ethanol extract of Cirsium japonicum attenuates hepatic lipid accumulation via AMPK activation in human HepG2 cells

One of the most common causes of chronic liver disease, nonalcoholic fatty liver disease (NAFLD), is strongly associated with obesity and dysregulated insulin action in the liver. However, there are no pharmacological agents currently established for the treatment of NAFLD. A flowering plant in the Asteraceae family, Cirsium japonicum (CJ), exhibits a variety of pharmacological and antioxidative properties that promote hepatoprotection. In the present study, CJ ethanol extract was shown to reduce hepatic triglyceride (TG) and cholesterol accumulation. CJ significantly increased AMP-activated protein kinase (AMPK) phosphorylation in HepG2 hepatocytes and downregulated the level of the target genes, acetyl-CoA carboxylase and fatty acid synthase. In addition, CJ upregulated the expression of carnitine palmitoyltransferase-1, which is involved in fatty acid oxidation. The results of the present study indicated that the positive effects of CJ extract on high-fat diet-induced hepatic TG accumulation were mediated via the AMPK signaling pathway, indicating a potential target for the preventative treatment of NAFLD.

Cordyceps militaris alleviates non-alcoholic fatty liver disease in ob/ob mice

BACKGROUND/OBJECTIVES

Non-alcoholic fatty liver disease (NAFLD) is becoming an important public health problem as metabolic syndrome and type 2 diabetes have become epidemic. In this study we investigated the protective effect of Cordyceps militaris (C. militaris) against NAFLD in an obese mouse model.

MATERIALS/METHODS

Four-week-old male ob/ob mice were fed an AIN-93G diet or a diet containing 1% C. militaris water extract for 10 weeks after 1 week of adaptation. Serum glucose, insulin, free fatty acid (FFA), alanine transaminase (ALT), and proinflammatory cytokines were measured. Hepatic levels of lipids, glutathione (GSH), and lipid peroxide were determined.

RESULTS

Consumption of C. militaris significantly decreased serum glucose, as well as homeostasis model assessment for insulin resistance (HOMA-IR), in ob/ob mice. In addition to lowering serum FFA levels, C. militaris also significantly decreased hepatic total lipids and triglyceride contents. Serum ALT activities and tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) levels were reduced by C. militaris. Consumption of C. militaris increased hepatic GSH and reduced lipid peroxide levels.

CONCLUSIONS

These results indicate that C. militaris can exert protective effects against development of NAFLD, partly by reducing inflammatory cytokines and improving hepatic antioxidant status in ob/ob mice.

Hydrogen sulfide and the liver

Hydrogen sulfide (H2S) is a gasotransmitter that regulates numerous physiological and pathophysiological processes in our body. Enzymatic production of H2S is catalyzed by cystathionine γ-lyase (CSE), cystathionine β-synthase (CBS), and 3-mercaptopyruvate sulfurtransferase (MST). All these three enzymes present in the liver and via H2S production regulate liver functions. The liver is the hub for metabolism of glucose and lipids, and maintains the level of circulatory lipids through lipoprotein metabolism. Hepatic H2S metabolism affects glucose metabolism, insulin sensitivity, lipoprotein synthesis, mitochondrial biogenetics and biogenesis. Malfunction of hepatic H2S metabolism may be involved in many liver diseases, such as hepatic fibrosis and hepatic cirrhosis.

Rosiglitazone and fenofibrate exacerbate liver steatosis in a mouse model of obesity and hyperlipidemia. A transcriptomic and metabolomic study

Peroxisome proliferator-activated receptors (PPAR) play an important role in the regulation of lipid and glucose metabolism, inflammatory, and vascular responses. We show the effect of treatment with two PPAR agonists, fenofibrate (FF) and rosiglitazone (RSG), on ob/ob and LDLR-double deficient mice, by combined gene-expression and metabolomic analyses. Male mice were daily treated for 12 weeks with RSG (10 mg·kg(1-)·day(-1) per os (p.o.), n = 8) and FF (50 mg·kg(1-)·day(-1) p.o., n = 8). Twelve untreated ob/ob and LDLR-double deficient mice were used as controls. To integrate the transcriptomic and metabolomic results, we designed a hierarchical algorithm, based on the average linkage method in clustering. Data were also interpreted with the Ingenuity Pathway Analysis program. FF and RSG treatments significantly increased the hepatic triglyceride content in the liver when compared with the control group, and the treatments induced an increase in the number and size of hepatic lipid droplets. Both drugs simultaneously activate pro-steatotic and antisteatotic metabolic pathways with a well-ordered result of aggravation of the hepatic lipid accumulation. The present study is a cautionary note not only to researchers on the basic mechanism of the action of PPAR activators but also to the use of these compounds in clinical practice.

Prognostic factors for regression from impaired glucose tolerance to normal glucose regulation in Japanese patients with nonalcoholic fatty liver disease

OBJECTIVE

The aim of this retrospective cohort study was to assess the predictive factors for the regression from impaired glucose tolerance (IGT) to normal glucose regulation (NGR) in patients with nonalcoholic fatty liver disease (NAFLD).

METHODS

A total of 164 NAFLD patients who had IGT in the first 75-g oral glucose tolerance test (OGTT) and underwent a repeated OGTT five years later were enrolled. A multivariate logistic regression analysis was carried out to identify factors predicting the regression from IGT to NGR.

RESULTS

Out of the 164 patients, 29 regressed from IGT to NGR within five years after the first OGTT. The multivariate analysis by logistic regression showed that regression from IGT to NGR occurred when the patient was young (risk ratio for ten years: 0.38; 95% confidence interval [CI] 0.20-0.72; p=0.003), had a fasting plasma glucose (FPG) level of <100 mg/dL (risk ratio: 6.53; 95%CI 1.88-21.73; p=0.003), had a 2-hr post-load plasma glucose (PG) level of <160 mg/dL (risk ratio: 4.86; 95%CI 1.08-22.72; p=0.040), a body mass index (BMI) decrease of ≥1.5 (risk ratio: 5.20; 95% CI 1.41-19.24; p=0.014), physical activity of ≥2 Metabolic Equivalent of Task (MET) h/day (risk ratio: 5.57; 95%CI 1.68-18.44; p=0.005), and showed disappearance of the fatty liver by ultrasonography at five years (risk ratio: 9.92; 95%CI 2.87-34.34; p<0.001).

CONCLUSION

Our results suggest that six factors: young age, FPG <100 mg/dL, 2-hr post-load PG of <160 mg/dL, BMI decrease of ≥1.5, physical activity of ≥2 MET h/day, and the disappearance of fatty liver predict the regression from IGT to NGR in NAFLD patients.

Bitter melon extract attenuating hepatic steatosis may be mediated by FGF21 and AMPK/Sirt1 signaling in mice

We sought to evaluate the effects of Momordica charantia (bitter melon, BM) extract on insulin sensitivity, NAFLD, hepatic FGF21 and AMPK signaling in mice fed a high-fat diet. Male C57/B6 mice were randomly divided into HFD and HFD supplementation with BM for 12 week. Body weight, plasma glucose, FGF21 and insulin levels, hepatic FGF21 and AMPK signaling proteins were measured. The results showed that plasma FGF21 and insulin concentrations were significantly decreased and hepatic FGF21 content was significantly down-regulated, while FGF receptors 1, 3 and 4 (FGFR1, FGFR3 and FGFR4) were greatly up-regulated in BM group compared to the HFD group (P < 0.05 and P < 0.01). BM also significantly increased hepatic AMPK p, AMPK α1 AMPK α2 and Sirt1 content compared to the HFD mice. We, for the first time, demonstrated that BM extract attenuated hepatic steatosis in mice by enhancing hepatic FGF21 and AMPK/Sirt1 signaling.

Endoscopic duodenal-jejunal bypass liner rapidly improves plasma parameters of nonalcoholic fatty liver disease

Bariatric surgery reduces nonalcoholic fatty liver disease (NAFLD). We investigated the effects of duodenal-jejunal bypass liner (DJBL), nonsurgical bariatric device, on plasma parameters of NAFLD. Seventeen obese subjects with type 2 diabetes received the DJBL for 24 weeks. Before, during, and after DJBL implantation, we determined plasma levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), γ-glutamyltransferase (γ-GT), albumin, caspase-cleaved cytokeratin-18 (CK-18), and liver fatty acid-binding protein (L-FABP). At baseline, subjects had increased levels of AST (35 ± 4 IU/L), ALT (54 ± 5 IU/L), and γ-GT (66 ± 14 IU/L), compared with healthy individuals; subjects' mean concentrations of caspase-cleaved CK-18 and L-FABP were 214.4 ± 35.6 U/L and 29.3 ± 2.6 ng/mL, respectively. Three months after implantation of DJBL, all NAFLD-related parameters had decreased from baseline (AST, 28 ± 3 IU/L; ALT, 32 ± 2 IU/L; γ-GT, 44 ±7 IU/L; caspase-cleaved CK-18, 140.6 ± 16.3U/L; and L-FABP, 18.2 ± 1.5 ng/mL; all P < .05). After 6 months, levels of ALT and γ-GT had further decreased (ALT, 28 ± 2 IU/L and γ-GT, 35 ± 5 IU/L), whereas levels of AST, caspase-cleaved CK-18, and L-FABP had stabilized (P = not significant). Six months after DJBLs were removed, levels of ALT (37 ± 3 IU/L), γ-GT (42 ± 5 IU/L), and caspase-cleaved CK-18 (124.5 ± 12.5U/L) were still reduced (P < .05), whereas AST and L-FABP had returned to near baseline levels (P = not significant). Therefore, in obese subjects, DJBL reduces plasma parameters of NAFLD. ClinicalTrials.gov, Number: NCT00985114.

Preoperative 4-week supplementation with omega-3 polyunsaturated fatty acids reduces liver volume and facilitates bariatric surgery in morbidly obese patients

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is a very common condition among obese patients that may lead to the enlargement of the liver, that in turn impairs the access to the gastro-esophageal junction during laparoscopic bariatric surgery. Omega-3 polyunsaturated fatty acids (Ω-3 PUFAs) supplementation has been shown to reduce nutritional hepatic steatosis. The aim of this study was to assess the effects of a 4-week course of oral Ω-3 PUFAs supplementation on the volume of the liver.

METHODS

20 morbidly obese patients were administered oral Ω-3 PUFAs (1,500 mg daily) for 4 weeks before undergoing the laparoscopic Roux-en-Y gastric bypass (LRYGBP) without any dietary restriction. The volume of the left hepatic lobe was estimated by liver ultrasonography at baseline and at the end of treatment. The degree of difficulty to access the gastro-esophageal junction was appreciated subjectively by the operating surgeon.

RESULTS

All patients completed the study and no side effect was reported. The mean volume of the left hepatic lobe decreased by 20% from 598 ± 97 to 484 ± 118 cm(3) after the treatment (p = 0.002). The access to the gastro-esophageal junction was reported as simple, with easy retraction of the left hepatic lobe by the operating surgeon in all cases.

CONCLUSIONS

This study demonstrates that a 4-week course of oral Ω-3 PUFAs supplementation results in a significant reduction in liver size that facilitates the LRYGBP.