Hepatic steatosis and type 2 diabetes mellitus

Blood pressure, gallstones, and age at first cholecystectomy in U.S. adults: a cross-sectional study

BACKGROUND

Gallstones are a prevalent health issue. Recent studies have revealed that blood pressure (BP) may affect gallstone formation. This study assessed the association between hypertension (HTN) and both the prevalence of gallstones and the age at first cholecystectomy among U.S. adults.

METHODS

Data were extracted from the National Health and Nutrition Examination Survey (NHANES) database from 2017 to 2020. Weighted logistic and linear regression analyses and subgroup analyses were employed to investigate the relationships between HTN, gallstone disease (GD), and age at first cholecystectomy. Additionally, this study employed generalized additive models (GAM) and smooth-fitting curves to delineate the relationships. The two-piecewise linear regression model and logarithmic likelihood ratio test elucidated the inflection point of systolic blood pressure (SBP) on the age at first cholecystectomy.

RESULTS

The study included 7,532 participants aged over 20 years. Of these, 817 reported a history of cholecystectomy, and 781 reported a history of gallstones. After adjustment for age, gender, race, diabetes, and hypercholesterolemia, HTN was significantly associated with gallstones in individuals aged 48 years (OR = 1.39; 95% CI: 1.03, 1.88). SBP was positively correlated with the age at first cholecystectomy (β = 0.20, 95% CI: 0.13, 0.26). When examining the correlation between SBP and age at surgery, age was first positively and then negatively correlated with BP, with 170 as an inflection point. We carried out subgroup analyses to evaluate the robustness of the link between HTN and cholecystectomy. The results revealed a consistent positive association between HTN and cholecystectomy across these variables (p > 0.05).

CONCLUSION

The study found a correlation between BP and the prevalence of gallstones in individuals aged 42 years and older and a positive association between SBP and the age at first cholecystectomy. While causality cannot be confirmed, these findings may assist in identifying early risk groups for GD and early cholecystectomy, thereby enhancing risk stratification and potentially reducing screening costs.

The Multifunctional Role of KCNE2: From Cardiac Arrhythmia to Multisystem Disorders

The KCNE2 protein is encoded by the kcne2 gene and is a member of the KCNE protein family, also known as the MinK-related protein 1 (MiRP1). It is mostly present in the epicardium of the heart and gastric mucosa, and it is also found in the thyroid, pancreatic islets, liver and lung, among other locations, to a lesser extent. It is involved in numerous physiological processes because of its ubiquitous expression and partnering promiscuity, including the modulation of voltage-dependent potassium and calcium channels involved in cardiac action potential repolarization, and regulation of secretory processes in multiple epithelia, such as gastric acid secretion, thyroid hormone synthesis, generation and secretion of cerebrospinal fluid. Mutations in the KCNE2 gene or aberrant expression of the protein may play a critical role in cardiovascular, neurological, metabolic and multisystem disorders. This article provides an overview of the advancements made in understanding the physiological functions in organismal homeostasis and the pathophysiological consequences of KCNE2 in multisystem diseases.

Potential role of gut microbiota in major depressive disorder: A review

Interactions between the gut microbiota and host immunity are sophisticated, dynamic, and host-dependent. Scientists have recently conducted research showing that disturbances in the gut bacterial community can lead to a decrease in some metabolites and, consequently, to behaviors such as depression. Exposure to stressors dropped the relative abundance of bacteria in the genus Bacteroides while soaring the relative abundance of bacteria in the genus Clostridium, Coprococcus, Dialister, and Oscillibacter, which were also reduced in people with depression. Microbiota and innate immunity are in a bilateral relationship. The gut microbiota has been shown to induce the synthesis of antimicrobial proteins such as catalysidins, type C lectins, and defensins. Probiotic bacteria can modulate depressive behavior through GABA signaling. The gut microbiome produces essential metabolites such as neurotransmitters, tryptophan metabolites, and short-chain fatty acids (SCFAs) that can act on the CNS. In the case of dysbiosis, due to mucin changes, the ratio of intestinal-derived molecules may change and contribute to depression. Psychotropics, including Bifidobacterium longum NCC3001, Clostridium butyricum CBM588, and Lactobacillus acidophilus, have mental health benefits, and can have a positive effect on the host-brain relationship, and have antidepressant effects. This article reviews current studies on the association between gut microbiota dysbiosis and depression. Comprehensively, these findings could potentially lead to novel approaches to improving depressive symptoms via gut microbiota alterations, including probiotics, prebiotics, and fecal microbiota transplantation.

Microbiota and Gut-Liver Axis: An Unbreakable Bond?

The gut microbiota, amounting to approximately 100 trillion (1014) microbes represents a genetic repertoire that is bigger than the human genome itself. Evidence on bidirectional interplay between human and microbial genes is mounting. Microbiota probably play vital roles in diverse aspects of normal human metabolism, such as digestion, immune modulation, and gut endocrine function, as well as in the genesis and progression of many human diseases. Indeed, the gut microbiota has been most closely linked to various chronic ailments affecting the liver, although concrete scientific data are sparse. In this narrative review, we initially discuss the basic epidemiology of gut microbiota and the factors influencing their initial formation in the gut. Subsequently, we delve into the gut-liver axis and the evidence regarding the link between gut microbiota and the genesis or progression of various liver diseases. Finally, we summarise the recent research on plausible ways to modulate the gut microbiota to alter the natural history of liver disease.

Targeted therapeutics and novel signaling pathways in non-alcohol-associated fatty liver/steatohepatitis (NAFL/NASH)

Non-alcohol-associated fatty liver/steatohepatitis (NAFL/NASH) has become the leading cause of liver disease worldwide. NASH, an advanced form of NAFL, can be progressive and more susceptible to developing cirrhosis and hepatocellular carcinoma. Currently, lifestyle interventions are the most essential and effective strategies for preventing and controlling NAFL without the development of fibrosis. While there are still limited appropriate drugs specifically to treat NAFL/NASH, growing progress is being seen in elucidating the pathogenesis and identifying therapeutic targets. In this review, we discussed recent developments in etiology and prospective therapeutic targets, as well as pharmacological candidates in pre/clinical trials and patents, with a focus on diabetes, hepatic lipid metabolism, inflammation, and fibrosis. Importantly, growing evidence elucidates that the disruption of the gut-liver axis and microbe-derived metabolites drive the pathogenesis of NAFL/NASH. Extracellular vesicles (EVs) act as a signaling mediator, resulting in lipid accumulation, macrophage and hepatic stellate cell activation, further promoting inflammation and liver fibrosis progression during the development of NAFL/NASH. Targeting gut microbiota or EVs may serve as new strategies for the treatment of NAFL/NASH. Finally, other mechanisms, such as cell therapy and genetic approaches, also have enormous therapeutic potential. Incorporating drugs with different mechanisms and personalized medicine may improve the efficacy to better benefit patients with NAFL/NASH.

The association between hypertension and the risk of gallstone disease: a cross-sectional study

BACKGROUND

To explore the association between hypertension and the risk of gallstone disease.

METHODS

We collected the data about the subjects receiving physical examination. Gallstone disease was diagnosed by abdominal ultrasound. Multivariable logistic regression was used to study the association between blood pressure and the risk of gallstone disease. SPSS version 23.0 was used for statistical analysis, and two-tailed P < 0.05 was defined as statistically significant.

RESULTS

A total of 318,403 people were included in the study and 171,276 (53.8%) of them were men and 147,127 (46.2%) were women. Among them, 27,463 (8.6%) were diagnosed with gallstone disease on ultrasound examination, with 12,452 (3.9%) cases of gallstones and 15,017 (4.7%) cases of cholecystectomy. Multivariable logistic regression showed that hypertension was significantly associated with the risk of gallstone disease (OR = 1.05; 95% CI: 1.02-1.10; P = 0.03) and gallstones (OR = 1.12; 95% CI: 1.06-1.19; P < 0.01) and the association between hypertension and gallstone disease was stronger in women than in men. However, hypertension was not significantly correlated with cholecystectomy (OR = 0.99; 95% CI: 0.95-1.04; P = 0.85). Additionally, results showed that with the severity of hypertension increased, the risk of gallstone disease was also marked elevated (P for trend < 0.001).

CONCLUSIONS

The gallstone disease was prevalent and hypertension is significantly associated with the gallstone disease risk with a significant dose-response association. This study showed that the association between hypertension and cholecystectomy was not statistically significant, maybe hypertension correlated with gallstones but not with symptomatic gallstone disease which would require cholecystectomy.

Pancreas morphogenesis and homeostasis depends on tightly regulated Zeb1 levels in epithelial cells

The pancreas is comprised of exocrine and endocrine compartments releasing digestive enzymes into the duodenum and regulating blood glucose levels by insulin and glucagon release. Tissue homeostasis is depending on transcription factor networks, involving Ptf1α, Ngn3, Nkx6.1, and Sox9, which are already activated during organogenesis. However, proper organ function is challenged by diets of high sugar and fat content, increasing the risk of type 2 diabetes and other disorders. A detailed understanding of processes that are important for homeostasis and are impaired during type 2 diabetes is lacking. Here, we show that Zeb1—a transcription factor known for its pivotal role in epithelial-mesenchymal transition, cell plasticity, and metastasis in cancer—is expressed at low levels in epithelial cells of the pancreas and is crucial for organogenesis and pancreas function. Loss of Zeb1 in these cells result in an increase of islet mass, impaired glucose tolerance, and sensitizes to develop liver and pancreas steatosis during diabetes and obesity. Interestingly, moderate overexpression of Zeb1 results in severe pancreas agenesis and lethality after birth, due to islet insufficiency and lack of acinar structures. We show that Zeb1 induction interferes with proper differentiation, cell survival, and proliferation during pancreas formation, due to deregulated expression of endocrine-specific transcription factors. In summary, our analysis suggests a novel role of Zeb1 for homeostasis in epithelial cells that is indispensable for pancreas morphogenesis and proper organ function involving a tight regulation of Zeb1 expression.

Therapeutic Potentials of Colocasia affinis Leaf Extract for the Alleviation of Streptozotocin-Induced Diabetes and Diabetic Complications: In vivo and in silico-Based Studies

INTRODUCTION

Hypoglycemia in diabetes mellitus (DM) correlates with hepatic impairment, nephropathy, lipid abnormalities, and oxidative stress and subsequently complicates the disease pathogenesis. Medicinal plants have been used for the management of diabetes since ancient times. In this study, we explored the potentials of Colocasia affinis (CA), a plant known to possess anti-allergic and anti-inflammatory activities, as a remedy for diabetes and related complications.

METHODS

We induced diabetes in rats using a single intraperitoneal dose (65 mg/kg) of streptozotocin (STZ). We next treated the rats with an ethanolic extract of leaves of CA to reveal its antidiabetic and organ-protective potentials. Biomarkers of diabetes, inflammation, and oxidative stress were measured using biochemical and histopathological analysis. We also performed molecular docking for three major phytochemicals (kaempferol, myricetin, and rosmarinic acid) of CA.

RESULTS

Oral administration of the CA leaves extract at 250 mg/kg and 500 mg/kg doses decreased blood glucose level significantly (p<0.05) in STZ-induced diabetic rats. The extract also considerably attenuated plasma HbA1c levels and normalized blood lipids, glycogen, alanine aminotransferase (ALT), and aspartate aminotransferase (AST). Additionally, treatment with the extract improved kidney complications by decreasing serum creatinine and blood urea nitrogen (BUN) levels. Furthermore, CA leaves extract normalized nitric oxide (NO) and advance oxidative protein products (AOPP) in diabetic rats. The extract also showed significant improvement of the antioxidant enzymes glutathione dismutase (GSH) and superoxide dismutase (SOD) at a dose of 500 mg/kg. Besides, histological investigation demonstrated attenuation of inflammation of the vital organs, including the liver and the kidney. In silico studies revealed that three major phytochemicals (kaempferol, myricetin, and rosmarinic acid) of the ethanolic extract of leaves of CA can inhibit several molecular targets of diabetes and inflammation.

CONCLUSION

Collectively, our results demonstrated the therapeutic potentials of CA for the mitigation of diabetes and diabetic complications.

Anti-hyperglycemic and hypolipidemic effects of black ginseng extract containing increased Rh4, Rg5, and Rk1 content in muscle and liver of type 2 diabetic db/db mice

Black ginseng (BG), which is produced by repeated steaming and drying of fresh ginseng, has various pharmacological and therapeutic properties. This study investigated the anti-hyperglycemic and hypolipidemic effects of BG ethanolic extract in type 2 diabetic db/db mice. The levels of fasting blood glucose, HbA1c, insulin levels and thiobarbituric acid reactive substances values were decreased in the groups fed BG extract (BG) (100 and 900 mg/kg BW/day), compared to the control group (CON). In the BG compared with the CON, hepatic steatosis in the liver and the size of adipocytes in muscle tissue were improved. The administration of BG regulated the glucose transporter type (GLUT) 4 and 2, and peroxisome proliferator-activated receptor (PPAR) α and γ in muscle and liver. Moreover, ginsenosides (Rh4, Rg5, and Rk1), which profiled by HPLC, regulated the markers for lipid metabolism and glucose metabolism; PPARs and GLUTs in muscle and C2C12 rather than liver cells and tissue. These findings suggested that ginsenosides (Rh4, Rg5, and Rk1) from BG extract can ameliorate type 2 diabetes through their anti-hyperglycemic and hypolipidemic effects.

The role of IFN in the development of NAFLD and NASH

Non-alcoholic fatty liver disease (NAFLD) and its progressive inflammatory form non-alcoholic steatohepatitis (NASH) are major health challenges due to a significant increase in their incidence and prevalence. While NAFLD is largely benign, the chronic liver inflammation in NASH patients may cause progression to liver cirrhosis and hepatocellular carcinoma. There is an urgent need for a better understanding of the factors, which drive the progression from NAFLD to NASH and how to use this information both to improve diagnostic and to develop new treatment strategies. Increasing evidence points to interferons (IFNs) as key players in NAFLD and particular in the progression to NASH. IFNs crucial role in disease development is supported by both genetic evidence and animal studies. In this review, we describe the involvement of both type I and type III IFNs in the development and progression of NAFLD and NASH.

The role of the gut microbiome in chronic liver disease: the clinical evidence revised

Recent research has suggested a role for the intestinal microbiota in the pathogenesis and potential treatment of a wide range of liver diseases. The intestinal microbiota and bacterial products may contribute to the development of liver diseases through multiple mechanisms including increased intestinal permeability, chronic systemic inflammation, production of short-chain fatty acids and changes in metabolism. This suggests a potential role for pre-, pro- and synbiotic products in the prevention or treatment of some liver diseases. In addition, there is emerging evidence on the effects of faecal microbial transplant. Herein, we discuss the relationship between the intestinal microbiota and liver diseases, as well as reviewing intestinal microbiota-based treatment options that are currently being investigated.

Repression of MicroRNA-30e by Hepatitis C Virus Enhances Fatty Acid Synthesis

Chronic hepatitis C virus (HCV) infection often leads to end‐stage liver disease, including hepatocellular carcinoma (HCC). We have previously observed reduced expression of microRNA‐30e (miR‐30e) in the liver tissues and sera of patients with HCV‐associated HCC, although biological functions remain unknown. In this study, we demonstrated that HCV infection of hepatocytes transcriptionally reduces miR‐30e expression by modulating CCAAT/enhancer binding protein β. In silico prediction suggests that autophagy‐related gene 5 (ATG5) is a direct target of miR‐30e. ATG5 is involved in autophagy biogenesis, and HCV infection in hepatocytes induces autophagy. We showed the presence of ATG5 in the miR‐30e–Argonaute 2 RNA‐induced silencing complex. Overexpression of miR‐30e in HCV‐infected hepatocytes inhibits autophagy activation. Subsequent studies suggested that ATG5 knockdown in Huh7.5 cells results in the remarkable inhibition of sterol regulatory element binding protein (SREBP)‐1c and fatty acid synthase (FASN) level. We also showed that overexpression of miR‐30e decreased lipid synthesis‐related protein SREBP‐1c and FASN in hepatocytes. Conclusion: We show new mechanistic insights into the interactions between autophagy and lipid synthesis through inhibition of miR‐30e in HCV‐infected hepatocytes.

Accuracy of ultrasonography in the assessment of liver fat compared with MRI

AIM

To investigate the accuracy of ultrasonography in the assessment of hepatic steatosis using magnetic resonance imaging (MRI) as standard of reference and to explore the influence of additional hepatic iron overload.

MATERIAL AND METHODS

A total of 2,783 volunteers (1,442 women, 1,341 men; mean age, 52.3±13.8 years) underwent confounder-corrected chemical-shift-encoded MRI of the liver at 1.5 T. Proton-density fat fraction (PDFF) and transverse relaxation rate (R2*) were calculated to estimate hepatic steatosis and liver iron overload, respectively. In addition, the presence of hepatic steatosis was assessed by B-mode ultrasonography. The sensitivity, specificity, and accuracy of hepatic ultrasonography were determined for different degrees of hepatic steatosis and different amounts of liver iron.

RESULTS

MRI revealed hepatic steatosis in 40% of participants (n=1,112), which was mild in 68.9% (n=766), moderate in 26.7% (n=297), and severe in 4.4% (n=49) of patients. Ultrasonography detected hepatic steatosis in 37.8% (n=1,052), corresponding to 74.5% sensitivity and 86.6% specificity. The sensitivity of ultrasound increased with the amount of hepatic fat present and was 65.1%, 95%, and 96% for low, moderate, and high fat content; whereas the specificity was constantly high at 86.6%. The diagnostic accuracy of ultrasound for detection of hepatic steatosis did not vary significantly with the amount of liver iron present.

CONCLUSION

Ultrasonography is an excellent tool to assess hepatic steatosis in the clinical setting with some limitations in patients with a low liver fat content. The detection of hepatic steatosis by ultrasonography is not influenced by liver iron.

Ellagic acid ameliorates AKT-driven hepatic steatosis in mice by suppressing de novo lipogenesis via the AKT/SREBP-1/FASN pathway

Ellagic acid alleviates hepatic lipid accumulation in mice by suppressing AKT-driven de novo lipogenesis.

Non-alcoholic fatty liver disease and obesity: the role of the gut bacteria

Non-alcoholic fatty-liver disease (NAFLD) is now considered one of the leading causes of liver disease worldwide and is associated with metabolic syndrome and obesity. There are several factors contributing to the disease state. Recent research suggests that the intestinal microbiota (IM) and bacterial products may play a role through several mechanisms which include increased energy uptake, intestinal permeability and chronic inflammation. In addition to diet and exercise, treatment options targeting the IM are being investigated and include the use of pre-, pro- and synbiotics as well as the possibility of fecal microbial transfers. This literature review explores the relationship between NAFLD and the IM as well as highlight new IM treatment options that may become available in the near future.

Non-alcoholic Fatty Liver Disease Is a Risk Factor for Type 2 Diabetes in Middle-aged Japanese Men and Women

Objective Emerging studies have focused on the association between non-alcoholic fatty liver disease (NAFLD) and the risk of type 2 diabetes mellitus (T2DM). We aimed to investigate whether NAFLD diagnosed by ultrasonography could predict the risk of future T2DM in a Japanese middle-aged health check population. Methods We conducted a 10-year observational study in a health checkup population of middle-aged Japanese men and women at Hidaka Hospital from 2004 to 2013. We excluded cases with an alcohol intake exceeding 20 g/day and those with impaired glucose tolerance. The remaining 1,544 men and 864 women were classified into fatty liver and non-fatty liver groups based on the findings of abdominal ultrasonography. Both groups were followed for the development of diabetes. A multiple regression analysis was performed for each variable to predict the risk of future diabetes. Results The median age of the participants was 46.0 years at the entry, and the follow-up period was 10 years. The incidence of diabetes in the fatty liver group was 12.5% (29/232) in men and 26.3% (10/38) in women, whereas the incidence of diabetes in the non-fatty liver group was 2.5% (34/1,312) in men and 1.8% (15/826) in women. The relative risk of diabetes associated with fatty liver was 4.8 [95% confidence interval (CI) 3.0-7.8, p<0.0001] in men and 14.5 (95% CI 7.0-30.1, p<0.0001) in women. Conclusion NAFLD was a significant predictor for future diabetes in a Japanese middle-aged health check population, especially in women.

Effect of Restriction of Foods with High Fructose Corn Syrup Content on Metabolic Indices and Fatty Liver in Obese Children

OBJECTIVE

We examined the effect of restriction of foods with high fructose content in obese school children.

METHODS

In a clinical study, we selected 54 obese children 6 to 11 years old with high fructose consumption (>70 g/day) in order indicate dietary fructose restriction (<20 g/day) for 6 weeks. Anthropometry, liver ultrasound as well as glucose, insulin, lipids, leptin, IGFBP1, and RBP4 serum levels were collected.

RESULTS

The group of children had 80% adherence and reported decreased fructose consumption (110 ± 38.6 to 11.4 ± 12.0 g/day) and also a significant decrease in caloric (2,384 ± 568 to 1,757 ± 387 kcal/day) and carbohydrate consumption (302 ± 80.4 to 203 ± 56.0 g/day). The severity of steatosis improved significantly after fructose restriction (p < 0.000001). However, no changes in BMI, systolic blood pressure, or diastolic blood pressure were found. Only triglyceride levels decreased (1.44 ± 0.43 to 1.31 ± 0.38 mmol/l), High-densitiy lipoprotein cholesterol showed a marginal increase (1.45 ± 0.19 to 1.56 ± 0.44 mmol/l). Insulin resistance and RBP4 did not change.

CONCLUSIONS

In school children, the restriction of high fructose foods with a decrease of caloric and carbohydrate intake at 6 weeks did not induce weight loss; however, triglyceride levels and hepatic steatosis decreased. Differences with other studies in regard to weight loss may be explained by adaptive changes on metabolic expenditure.

Non alcoholic fatty liver disease in a Nigerian population with type II diabetes mellitus

Introduction

Worldwide, Non-alcoholic fatty liver disease (NAFLD) has become an important cause of chronic liver disease and cardiovascular morbidity, even more so in subjects with Type II Diabetes Mellitus (T2DM). The aim of this study was to determine the prevalence and risk factors of NAFLD in an African population with Type II Diabetes Mellitus.

Methods

We performed a case control study and evaluated anthropometric and biochemical risk factors for NAFLD in 336 subjects (T2DM and non-diabetic controls). Parameters assessed included estimation of BMI (Body Mass Index), measurement of waist circumference (WC), serum cholesterol including HDL-C, LDL-C and triglyceride and serum transaminases (ALT and AST). Hepatitis B and C viral antibody screening was also performed. The diagnosis of NAFLD was confirmed by identification of hepatic steatosis on abdominal ultrasound scan evaluation and exclusion of significant alcohol consumption.

Results

NAFLD was identified in 16.7% (28 of 168) patients with T2DM compared with 1.2% (2 of 168) non-diabetic controls (Odds Ratio 16.6; p < 0.001). Central obesity (WC > 102cm) and dyslipidaemia (HDL-c < 40mg/dl) were independently associated with NAFLD in male subjects with T2DM (p = 0.03 and p = 0.04 respectively).

Conclusion

NAFLD occurred more frequently in patients with T2DM than controls and was associated with central obesity and dyslipidaemia. The diabetic subjects with NAFLD will require more intensive therapy to decrease the risk of hepatic, cardiovascular and other adverse events.

Kcne2 deletion causes early-onset nonalcoholic fatty liver disease via iron deficiency anemia

Nonalcoholic fatty liver disease (NAFLD) is an increasing health problem worldwide, with genetic, epigenetic, and environmental components. Here, we describe the first example of NAFLD caused by genetic disruption of a mammalian potassium channel subunit. Mice with germline deletion of the KCNE2 potassium channel β subunit exhibited NAFLD as early as postnatal day 7. Using mouse genetics, histology, liver damage assays and transcriptomics we discovered that iron deficiency arising from KCNE2-dependent achlorhydria is a major factor in early-onset NAFLD in Kcne2(─/─) mice, while two other KCNE2-dependent defects did not initiate NAFLD. The findings uncover a novel genetic basis for NAFLD and an unexpected potential factor in human KCNE2-associated cardiovascular pathologies, including atherosclerosis.

The Relationship between 10-Year Cardiovascular Risk Calculated Using the Pooled Cohort Equation and the Severity of Non-Alcoholic Fatty Liver Disease

BACKGROUND

We investigated the association between the severity of non-alcoholic fatty liver disease (NAFLD) and the estimated 10-year risk of cardiovascular disease (CVD) calculated by Pooled Cohort Equation (PCE) and Framingham risk score (FRS).

METHODS

A total of 15,913 participants (mean age, 46.3 years) in a health screening program were selected for analysis. The presence and severity of fatty liver was assessed by abdominal ultrasonogram. Subjects who drank alcohol more than three times a week were excluded from the study.

RESULTS

Among the participants, 57.6% had no NAFLD, 35.4% had grade I, 6.5% had grade II, and 0.5% had grade III NAFLD. Mean estimated 10-year CVD risk was 2.59%, 3.93%, 4.68%, and 5.23% calculated using the PCE (P for trend <0.01) and 4.55%, 6.39%, 7.33%, and 7.13% calculated using FRS, according to NAFLD severity from none to severe (P for trend <0.01). The odds ratio for ≥7.5% estimated CVD risk calculated using the PCE showed a higher correlation with increasing severity of NAFLD even after adjustment for conventional CVD risk factors (1.52, 2.56, 3.35 vs. the no NAFLD group as a reference, P<0.01) compared with calculated risk using FRS (1.65, 1.62, 1.72 vs. no NAFLD group as a reference, P<0.01).

CONCLUSION

In our study of apparently healthy Korean adults, increasing severity of NAFLD showed a higher correlation with estimated 10-year CVD risk when calculated using the PCE than when calculated using FRS.

Change in fatty liver status and 5-year risk of incident metabolic syndrome: a retrospective cohort study

INTRODUCTION

Fatty liver is associated with metabolic syndrome (MetS) but it may also occur without MetS. Whether resolution of fatty liver in the general population affects risk of MetS is unknown. Our aim was to determine whether a change in fatty liver status (either the development of new fatty liver or the resolution of existing fatty liver) would modify the risk of de novo MetS.

METHODS

Two thousand eighty-nine people without hypertension, diabetes, and MetS were examined at baseline and at 5-year follow-up using a retrospective cohort study design. Fatty liver status was assessed at baseline and at follow-up by ultrasonography. Adjusted hazard ratios (aHR) and 95 % confidence intervals (CIs) for de novo MetS at follow-up were calculated controlling for the potential confounders, compared to the reference group (people who never had fatty liver at baseline and follow-up).

RESULTS

During follow-up, fatty liver developed in 251 people and fatty liver resolved in 112 people. After the adjustment for multiple confounders, persisting fatty liver and incident fatty liver development were associated with de novo MetS, with aHR of 2.60 (95 % CIs [1.61,4.20]) and 3.31 (95 % CIs [1.99,5.51]), respectively. Risk of new MetS in resolved fatty liver group was attenuated with insignificant aHR of 1.29 accompanying 95 % CIs of 0.60 and 2.80.

DISCUSSION

Development or maintenance of fatty liver is positively associated with occurrence of new MetS. Resolution of fatty liver status has similar risk of de novo MetS with those who never had fatty liver. Therefore, cautious management is needed with those with fatty liver.

Liraglutide reduces fatty degeneration in hepatic cells via the AMPK/SREBP1 pathway

Recent studies have suggested that liraglutide could have a potential function in improving non-alcoholic fatty liver disease (NAFLD); however, the underlying molecular mechanism remains unclear. The aim of the present study was to investigate the role of the AMP-activated protein kinase (AMPK)/sterol regulatory element binding protein 1 (SREBP1) pathway in mediating the effect of liraglutide in reducing fatty degeneration in an in vitro NAFLD model. To resemble the NAFLD condition in vitro, L-02 cells were treated with 0.5 mM free fatty acids (FFAs) for 24 h. Liraglutide could affect the expression of AMPKα1, phosphorylated AMPKα1 and SREBP1 in a dose-dependent manner in FFA-exposed L-02 cells, as demonstrated by western blot analysis. The intracellular lipid accumulation was significantly decreased, as shown by oil red O staining. A significant decrease in the content of triglyceride and total cholesterol was observed when the FFA-exposed L-02 cells were incubated with liraglutide. In addition, the increased expression of liver-type fatty acid-binding protein in FFA-exposed L-02 cells was suppressed by liraglutide. These effects were reversed by compound C, an AMPK inhibitor. In conclusion, this study has demonstrated that liraglutide can reduce fatty degeneration induced by FFAs in hepatocytes, and this effect may be partially mediated by the AMPK/SREBP1 pathway.

Effect of Centaurium erythraea Rafn, Artemisia herba-alba Asso and Trigonella foenum-graecum L. on liver fat accumulation in C57BL/6J mice with high-fat diet-induced type 2 diabetes

ETHNOPHARMACOLOGICAL RELEVANCE

Centaurium erythraea Rafn (CE), Artemisia herba-alba Asso (AHA) and Trigonella foenum-graecum L. (TFG) are traditionally used to treat type 2 diabetes in Algeria, previous studies have found that extracts of these plants were effective to treat or prevent experimental diabetes induced by high-fat diet (HFD).

AIM OF THE STUDY

Describe the additional effects of these extracts on lipid tissue deposition in HFD.

MATERIALS AND METHODS

Male C57BL/6J mice were fed with HFD to induce type 2 Diabetes. Groups of mice were given plant extracts orally at 2g/kg/bodyweight daily for 20 weeks during establishment of diabetes, or for 18 weeks after confirmation of diabetes at the 17th week. Liver and other tissue samples were stained with Oil Red O.

RESULTS

Liver steatosis was confirmed with HFD. CE, AHA and TFG extracts improved liver steatosis by the end of the preventive (20 weeks) and curative periods (35 weeks). This was most marked for CE extract (p<0.05), less so with TFG and AHA. No steatosis was found in other tissues.

CONCLUSION

CE extract had a clear hepatoprotective effect in this mouse model of diet-induced type 2 diabetes. AHA and TFG had a minimal or no significant effect on steatosis. Beyond its effect as an antidiabetic agent, CE may also be promising to prevent or treat non-alcoholic liver steatosis.

Hepatoprotective and Pancreatoprotective Properties of the Ethanolic Extract of Nigerian Propolis

Objective:

Increased oxidative stress is associated with the progression of diabetic mellitus. In the present study, we investigated the effects of the ethanolic extract of Nigerian propolis (N. propolis) on markers of oxidative stress, histology of the liver and pancreas and glycaemia in alloxan-induced diabetic rats.

Materials and Methods:

Alloxan-induced hyperglycemic Wistar rats were treated with either metformin (150 mg/kg/d) or N. propolis (200 mg/kg/d and 300 mg/kg/d) for 28 days. At the end of the treatment period, the rats were sacrificed; blood was collected for biochemical analysis while their pancreases and liver were excised and processed for histological studies.

Results:

Serum oxidative stress markers and blood glucose concentration were compared between the treated and control rats. In contrast to the non-treated diabetic rats, blood glucose concentration were not significantly different between treated rats and control (P < 0.05) at 28 days of treatment with N. propolis and metformin. Serum malondialdehyde levels was reduced while superoxide dismutase levels were elevated in the N. propolis group; these levels were converse in the diabetic group, these differences are statistically significant (P<0.05) when compared with the control. Histologically, there was improvement in the treated group compared to the untreated group.

Conclusion:

These findings suggest that the N. propolis confers protection against hyperglycemia-induced oxidative stress in both liver and pancreas of adult Wistar rats.

Exendin-4 attenuates endoplasmic reticulum stress through a SIRT1-dependent mechanism

Accumulation of excess hepatic lipids contributes to insulin resistance and liver disease associated with endoplasmic reticulum (ER) stress. Exendin-4 is an agonist of the glucagon-like peptide 1 receptor and plays a role in improving insulin resistance and liver disease by increasing silent mating type information regulation 2 homolog (SIRT) 1. However, the effects and mechanism of action of exendin-4 on responses to palmitic acid (PA)-induced ER stress in hepatocytes have not been clearly defined. We investigated whether exendin-4 attenuates PA-induced ER stress via SIRT1 in HepG2 cells. PA treatment induced increased expression of PRKR-like endoplasmic reticulum kinase, inositol-requiring kinase 1α (IRE1α), activating transcription factor 6 (ATF6), and C/EBP homologous protein (CHOP) mRNA. Exendin-4 decreased the expression of P-IRE1α, ATF6, X-box binding protein-1 and CHOP, and increased the expression of SERCA2b. A significant decrease in the hepatic expression of PUMA, BAX, cytochrome c, and cleaved caspase-3 were observed in hepatocytes treated with exendin-4. The TUNEL assay consistently showed that exendin-4 reversed hepatocyte apoptosis induced by treatment with PA. Inhibition of SIRT1 by nicotinamide and siRNA significantly increased the expression of ER stress marker genes in cells treated with both PA and exendin-4. In conclusion, increased SIRT1 by exendin-4 attenuates PA-induced ER stress and mitochondrial dysfunction in hepatocytes.

Clinical approaches to non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) ranges from simple steatosis to nonalcoholic steatohepatitis (NASH), leading to fibrosis and potentially cirrhosis, and it is one of the most common causes of liver disease worldwide. NAFLD is associated with other medical conditions such as metabolic syndrome, obesity, cardiovascular disease and diabetes. NASH can only be diagnosed through liver biopsy, but noninvasive techniques have been developed to identify patients who are most likely to have NASH or fibrosis, reducing the need for liver biopsy and risk to patients. Disease progression varies between individuals and is linked to a number of risk factors. Mechanisms involved in the pathogenesis are associated with diet and lifestyle, influx of free fatty acids to the liver from adipose tissue due to insulin resistance, hepatic oxidative stress, cytokines production, reduced very low-density lipoprotein secretion and intestinal microbiome. Weight loss through improved diet and increased physical activity has been the cornerstone therapy of NAFLD. Recent therapies such as pioglitazone and vitamin E have been shown to be beneficial. Omega 3 polyunsaturated fatty acids and statins may offer additional benefits. Bariatric surgery should be considered in morbidly obese patients. More research is needed to assess the impact of these treatments on a long-term basis. The objective of this article is to briefly review the diagnosis, management and treatment of this disease in order to aid clinicians in managing these patients.

Selective hepatic insulin resistance in a murine model heterozygous for a mitochondrial trifunctional protein defect

Earlier reports suggest a link between mitochondrial dysfunction and development of hepatic insulin resistance. Here we used a murine model heterozygous (HET) for a mitochondrial trifunctional protein (MTP) gene defect to determine if a primary defect in mitochondrial long-chain fatty acid oxidation disrupts hepatic insulin action. Hyperinsulinemic-euglycemic clamps and signaling studies were performed for assessment of whole-body and hepatic insulin resistance/signaling. In addition, hepatic fatty acid oxidation and hepatic insulin action were assessed in vitro using primary hepatocytes isolated from HET and wildtype (WT) mice. In both hepatic mitochondria and isolated primary hepatocytes, heterozygosity of MTP caused an ∼50% reduction in mitochondrial fatty acid oxidation, a significantly impaired glucose disposal during the insulin clamp, and a markedly lower insulin-stimulated suppression of hepatic glucose production. HET mice also exhibited impaired insulin signaling, with increased hepatic phosphorylation of IRS2 (ser731) and reduced Akt phosphorylation (ser473) in both hepatic tissue and isolated primary hepatocytes. Assessment of insulin-stimulated FOXO1/phospho-FOXO1 protein content and PEPCK/G6Pase messenger RNA (mRNA) expression did not reveal differences between HET and WT mice. However, insulin-induced phosphorylation of GSK3β was significantly blunted in HET mice. Hepatic insulin resistance was associated with an increased methylation status of the catalytic subunit of protein phosphatase 2A (PP2A-C), but was not associated with differences in hepatic diacylglycerol content, activated protein kinase C-ϵ (PKC-ϵ), inhibitor κB kinase β (IKK-β), c-Jun N-terminal kinase (JNK), or phospho-JNK protein contents. Surprisingly, hepatic ceramides were significantly lower in the HET mice compared with WT.

CONCLUSION

A primary defect in mitochondrial fatty acid β-oxidation causes hepatic insulin resistance selective to hepatic glycogen metabolism that is associated with elevated methylated PP2A-C, but independent of other mechanisms commonly considered responsible for insulin resistance. (HEPATOLOGY 2013;).

Pathophysiology and Long-Term Management of the Metabolic Syndrome

The metabolic syndrome has been characterized by a cluster of abnormalities that include obesity, hyperglycemia, dyslipidemia, and hypertension. Other conditions associated with this syndrome include microalbuminuria, inflammation, a prothrombotic state, and a fatty liver. Together, these abnormalities lead to an environment where the risk of developing both type 2 diabetes and atherosclerotic cardiovascular disease are greatly enhanced. Recognition of this syndrome by practitioners, early treatment, and long-term management are crucial for disease prevention. Successful treatment requires the introduction of lifestyle changes initially and pharmacotherapy subsequently if lifestyle changes are not sufficient.

Hepatitis C virus activates the mTOR/S6K1 signaling pathway in inhibiting IRS-1 function for insulin resistance

Hepatitis C virus (HCV) infection significantly increases the prevalence of type 2 diabetes mellitus (T2DM). Insulin receptor substrate 1 (IRS-1) plays a key role in insulin signaling, thus enabling metabolic regulation in mammalian cells. We have previously shown that HCV infection modulates phosphorylation of Akt, a downstream target of IRS-1. In this study, we further examined the status of total IRS-1 and the downstream regulation of the Akt pathway in understanding mTOR/S6K1 signaling using HCV genotype 2a (clone JFH1)-infected hepatocytes. Inhibition of IRS-1 expression was observed in HCV-infected hepatocytes compared to that in a mock-infected control. The status of the tuberous sclerosis complex (TSC-1/TSC-2) was significantly decreased after HCV infection of human hepatocytes, showing a modulation of the downstream Akt pathway. Subsequent study indicated an increased level of Rheb and mTOR expression in HCV-infected hepatocytes. Interestingly, the phosphoS6K1 level was higher in HCV-infected hepatocytes, suggesting a novel mechanism for IRS-1 inhibition. Ectopic expression of TSC-1/TSC-2 significantly recovered the IRS-1 protein expression level in HCV-infected hepatocytes. Further analyses indicated that HCV core protein plays a significant role in modulating the mTOR/S6K1 signaling pathway. Proteasome inhibitor MG 132 recovered IRS-1 and TSC1/2 expression, suggesting that degradation occurred via the ubiquitin proteasome pathway. A functional consequence of IRS-1 inhibition was reflected in a decrease in GLUT4 protein expression and upregulation of the gluconeogenic enzyme PCK2 in HCV-infected hepatocytes. Together, these observations suggested that HCV infection activates the mTOR/S6K1 pathway in inhibiting IRS-1 function and perturbs glucose metabolism via downregulation of GLUT4 and upregulation of PCK2 for insulin resistance.

Antidiabetic effect of total saponins from Entada phaseoloides (L.) Merr. in type 2 diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

The seed of Entada phaseoloides (L.) Merr. (Entada phaseoloides) has been long used as an effective herb for the treatment of Diabetes mellitus by Dai people, one of the Chinese ethnic minorities. Saponin is an abundant type of secondary metabolic products in the seed of this plant. The aim of this study is to evaluate the potential therapeutic effects of total saponins from Entada phaseoloides (TSEP) in experimental type 2 Diabetes mellitus (T2DM) rats.

MATERIALS AND METHODS

T2DM rats were induced by high-fat diet and low-dose streptozotocin (STZ). Then different oral doses of TSEP (25, 50 and 100 mg/kg) were administrated to T2DM rats for 21 days. For comparison, a standard antidiabetic drug, metformin (200 mg/kg), was used as a positive control drug. Then the relative biochemical analysis and histopathological examination were made to evaluate the antidiabetic effect of TSEP.

RESULTS

TSEP dramatically reduced fasted blood glucose and serum insulin levels and alleviates hyperglycemia associated oxidative stress in T2DM rats. Moreover, a significantly hypolipidemic effect and an improvement in tissue steatosis could be observed after TSEP administration. Further investigations revealed a possible anti-inflammation effect of TSEP by examining serum levels of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α) and C-reactive protein (CRP). The effects of TSEP exhibited a dose-dependent manner and were comparable to metformin.

CONCLUSION

Our present study demonstrates both hypoglycemic and hypolipidemic activities of TSEP in T2DM rats, which support its antidiabetic property. This work also implies a possibility that TSEP exerts its therapeutic effect through repressing chronic inflammation responses.

In vitro evidence for chronic alcohol and high glucose mediated increased oxidative stress and hepatotoxicity

BACKGROUND

Hyperglycemia or alcoholism can lead to impaired liver functions. Cytochrome P450 2E1 (CYP2E1) is elevated in hyperglycemia or alcoholism and plays a critical role in generating oxidative stress in the cell.

METHODS

In the present study, we have used VL-17A cells that overexpress the alcohol metabolizing enzymes [alcohol dehydrogenase (ADH) and CYP2E1] to investigate the toxicity due to ethanol (EtOH) plus high glucose. Toxicity was assessed through viability assay and amount of acetaldehyde adduct formation. Oxidative stress parameters included measuring reactive oxygen species (ROS) levels and malondialdehyde adduct formation. Apoptosis was determined through caspase-3 activity, Annexin V- Propidium iodide staining, and changes in mitochondrial membrane potential. The effects of antioxidants and specific inhibitors of ADH and CYP2E1 on cell viability and ROS levels were also studied.

RESULTS

When present together, EtOH plus high glucose-treated VL-17A cells exhibited greater oxidative stress and toxicity than other groups. Apoptosis was observed in liver cells treated with the toxins, and the EtOH plus high glucose-treated VL-17A cells exhibited apoptosis to the largest extent. A distinct and graded increase in CYP2E1 level occurred in the different groups of VL-17A cells. Further, antioxidants or inhibitors of ADH and CYP2E1 were effective in decreasing the observed oxidative stress and toxicity.

CONCLUSIONS

The combined oxidative insult due to alcohol plus high glucose leads to greater liver injury, which may prove to be a timely warning for the injurious effects of alcohol consumption in diabetics.

Kinetic studies to investigate lipoprotein metabolism

To develop novel strategies for the prevention and treatment of dyslipidaemia, it is essential to understand the pathophysiology of dyslipoproteinaemia in humans. Lipoprotein metabolism is a complex system in which abnormal concentrations of various lipoprotein particles can result from alterations in their rates of production, conversion and/or catabolism. Traditional methods that measure plasma lipoprotein concentrations only provide static estimates of lipoprotein metabolism and hence limited mechanistic information. By contrast, the use of tracers labelled with stable isotopes and mathematical modelling provides a powerful tool for probing lipid and lipoprotein kinetics in vivo and furthering understanding of the pathogenesis of dyslipoproteinaemia.

Proteomics analysis of human nonalcoholic fatty liver

Nonalcoholic fatty liver disease (NAFLD) is being increasingly recognized as a major cause of liver-related morbidity and mortality. Given the increasing prevalence of obesity in western countries, NAFLD has become an important public health problem. The principal aim of this study was to find differences in protein expression between patients with NAFLD and healthy controls. Changes in protein expression of liver samples from controls, nonalcoholic steatosis, and nonalcoholic steatohepatitis (NASH) subjects were analyzed by two-dimensional differential in-gel electrophoresis (DIGE). With this proteomic technique, hundreds of proteins can be analyzed simultaneously and their relative abundance can be calculated. Proteins showing significant changes (ratio ≥ 1.5, p < 0.05) were identified by MALDI TOF/TOF mass spectrometry. Western blot of tissue homogenates was then used as a complementary method to validate protein expression changes observed by DIGE. With the aim to have a noninvasive approach to detect changes produced in NAFLD-affected liver, validated proteins were further tested in serum samples of different cohorts of patients. Following this approach, we identified two candidate markers CPS1 and GRP78 that were differentially expressed between control, steatosis, and NASH. This proteomics approach demonstrates that DIGE combined with MALDI TOF/TOF and Western blot analysis of tissue and serum samples is a useful approach to identify candidate markers associated with NAFLD.

Prolonged caloric restriction in obese patients with type 2 diabetes mellitus decreases plasma CETP and increases apolipoprotein AI levels without improving the cholesterol efflux properties of HDL

OBJECTIVE

Using a mouse model for human-like lipoprotein metabolism, we observed previously that reduction of the hepatic triglyceride (TG) content resulted in a decrease in plasma cholesteryl ester transfer protein (CETP) and an increase in HDL levels. The aim of the current study was to investigate the effects of prolonged caloric restriction in obese patients with type 2 diabetes mellitus, resulting in a major reduction in hepatic TG content, on plasma CETP and HDL levels.

RESEARCH DESIGN AND METHODS

We studied 27 obese (BMI: 37.2 ± 0.9 kg/m(2)) insulin-dependent patients with type 2 diabetes mellitus (14 men and 13 women, aged 55 ± 2 years) who received a 16-week very low calorie diet (VLCD). At baseline and after a 16-week VLCD, plasma lipids, lipoproteins, and CETP were measured. Furthermore, functionality of HDL with respect to inducing cholesterol efflux from human monocyte cells (THP-1) was determined.

RESULTS

A 16-week VLCD markedly decreased plasma CETP concentration (-18%; P < 0.01) and increased plasma apolipoprotein (apo)AI levels (+16%; P < 0.05), without significantly affecting plasma HDL-cholesterol and HDL-phospholipids. Although a VLCD results in HDL that is less lipidated, the functionality of HDL with respect to inducing cholesterol efflux in vitro was unchanged.

CONCLUSIONS

The marked decrease in hepatic TG content induced by a 16-week VLCD is accompanied by a decrease in plasma CETP concentration and an increase in apoAI levels, without improving the cholesterol efflux properties of HDL in vitro.

A defect in the activities of Δ and Δ desaturases and pro-resolution bioactive lipids in the pathobiology of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is a low-grade systemic inflammatory condition, since liver and adipose tissue tumor necrosis factor-α (TNF-α) and TNF receptor 1 transcripts and serum TNF-α levels are increased and IL-6(-/-) mice are less prone to NAFLD. Fatty liver damage caused by high-fat diets is associated with the generation of pro-inflammatory prostaglandin E(2) (PGE(2)). A decrease in the levels of arachidonic acid (AA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and the usefulness of EPA and DHA both in the prevention and management of NAFLD has been reported. AA, EPA and DHA and their anti-inflammatory products lipoxins (LXs), resolvins and protectins suppress IL-6 and TNF-α and PGE(2) production. These results suggest that the activities of Δ(6) and Δ(5) desaturases are reduced in NAFLD and hence, the dietary essential fatty acids, linoleic acid (LA) and α-linolenic acid (ALA) are not metabolized to their long-chain products AA, EPA and DHA, the precursors of anti-inflammatory molecules, LXs, resolvins and protectins that could pre vent NAFLD. This suggests that an imbalance between pro- and anti-inflammatory bioactive lipids contribute to NAFLD. Hence, it is proposed that plasma and tissue levels of AA, EPA, DHA and LXs, resolvins and protectins could be used as predictors and prognostic biomarkers of NAFLD. It is suggested that the synthesis and use of more stable analogues of LXs, resolvins and protectins need to be explored in the prevention and management of NAFLD.

Inflammatory stress exacerbates ectopic lipid deposition in C57BL/6J mice

Background

Chronic systemic inflammation and abnormal free fatty acid metabolism are closely related to ectopic lipid deposition. In this study, we investigate if inflammation tissue-specifically disrupts lipogenesis and lipolysis in nonadipose tissues and adipose tissue, resulting in ectopic lipid deposition in C57BL/6J mice.

Methods

We used casein injection in C57BL/6J mice to induce a chronic systemic inflammatory stress in vivo. Serum was analyzed for free fatty acid and cytokines. Insulin sensitivities were evaluated by glucose and insulin tolerance tests. Liver, muscle, adipose tissues were taken for lipid analysis. Real-time polymerase chain reaction and western blotting were used to examine the gene and protein expression of molecules involved in adipogenesis and lipolysis in tissues.

Results

Casein injection elevated serum levels of IL-6 and SAA in mice, which are associated with increased lipid accumulation in liver and muscle, suggesting that chronic systemic inflammation induces ectopic lipid deposition in nonadipose tissues. The inflammatory stress upregulated mRNA and protein expression of sterol regulatory element binding protein 1, fatty acid synthase, and acetyl CoA carboxylase alpha, while inhibited these molecules expression in adipose. Interestingly, in the same experimental setting, inflammation increased triglyceride lipase and hormone-sensitive lipase expression in white adipose tissue. Inflammation also induced insulin resistance and increased serum free fatty acid levels in C57BL/6J mice.

Conclusions

Chronic systemic inflammation increased lipogenesis in nonadipose tissues and lipolysis in white adipose tissue, resulting in ectopic lipid deposition in nonadipose tissues. This disturbed free fatty acid homeostasis and caused insulin resistance in C57BL/6J mice.

Long-term adaptation of global transcription and metabolism in the liver of high-fat diet-fed C57BL/6J mice

SCOPE

This study investigated the global transcriptional and metabolic changes occurring at multiple time points over 24 wk in response to a high-fat diet (HFD).

METHODS AND RESULTS

C57BL/6J mice were fed a HFD or normal diet (ND) over 24 wk. HFD-fed mice developed early clinical indicators of obesity-related co-morbidities including fatty liver, insulin resistance, hyperglycemia and hypercholesterolemia. Time-course microarray analysis at eight time points over 24 wk identified 332 HFD responsive genes as potential targets to counteract diet-induced obesity (DIO) and related co-morbidities. Glucose regulating enzyme activity and gene expression were altered early in the HFD-fed mice. Fatty acid (FA) and triglyceride (TG) accumulation in combination with inflammatory changes appear to be likely candidates contributing to hepatic insulin resistance. Cidea seemed to be one of representative genes related to these changes.

CONCLUSION

Global transcriptional and metabolic profiling across multiple time points in liver revealed potential targets for nutritional interventions to reverse DIO. In future, new approaches targeting HFD responsive genes and hepatic metabolism could help ameliorate the deleterious effects of an HFD and DIO-related complication.

The global epidemiology of hepatocellular carcinoma: present and future

The global risk of hepatocellular carcinoma (HCC) has been largely driven by hepatitis B virus (HBV) infection for the past century, along with hepatitis C virus (HCV), aflatoxin, excessive alcohol consumption, and obesity/diabetes. The dominant effect of HBV on global HCC risk should decline as the population vaccinated against HBV grows older. Infection with HCV is also expected to decline. Projections of HCV-related HCC rates remaining high for another 30 years may be overly pessimistic. Alcohol may be less of a factor in HCC in coming years. However, obesity and diabetes may become even more important risk factors for HCC.

Dietary fat intake promotes the development of hepatic steatosis independently from excess caloric consumption in a murine model

Nonalcoholic fatty liver disease results from overconsumption and is a significant and increasing cause of liver failure. The type of diet that is conducive to the development of this disease has not been established, and evidence-based treatment options are currently lacking. We hypothesized that the onset of hepatic steatosis is linked to the consumption of a diet with a high fat content, rather than related to excess caloric intake. In addition, we also hypothesized that fully manifested hepatic steatosis could be reversed by reducing the fat percentage in the diet of obese mice. C57BL/6J male mice were fed either a purified rodent diet containing 10% fat or a diet with 60% of calories derived from fat. A pair-feeding design was used to distinguish the effects of dietary fat content and caloric intake on dietary-induced hepatic lipid accumulation and associated injury. Livers were analyzed by quantitative reverse transcriptase polymerase chain reaction for lipid metabolism-related gene expression. After 9 weeks, mice on the 60%-fat diet exhibited more weight gain, insulin resistance, and hepatic steatosis compared with mice on a 10%-fat diet with equal caloric intake. Furthermore, mice with established metabolic syndrome at 9 weeks showed reversal of hepatic steatosis, insulin resistance, and obesity when switched to a 10%-fat diet for an additional 9 weeks, independent of caloric intake. Quantitative reverse transcriptase polymerase chain reaction revealed that transcripts related to both de novo lipogenesis and increased uptake of free fatty acids were significantly up-regulated in mice pair-fed a 60%-fat diet compared with 10%-fat-fed animals. Dietary fat content, independent from caloric intake, is a crucial factor in the development of hepatic steatosis, obesity, and insulin resistance in the C57BL/6J diet-induced obesity model caused by increased uptake of free fatty acids and de novo lipogenesis. In addition, once established, all these features of the metabolic syndrome can be successfully reversed after switching obese mice to a diet low in fat. Low-fat diets deserve attention in the investigation of a potential treatment of patients with nonalcoholic fatty liver disease.

Non-alcoholic fatty liver disease proteomics

PURPOSE

Non-alcoholic fatty liver disease (NAFLD) is an important cause of chronic liver injury that has gained concern in clinical hepatology. The principal aim of this study was to find differences in protein expression between patients with NAFLD and healthy controls.

EXPERIMENTAL DESIGN

Changes in protein expression of liver samples from each of the three groups of subjects, controls, non-alcoholic steatosis, and non-alcoholic steatohepatitis (NASH), were analyzed by DIGE combined with MALDI TOF/TOF analysis, a proteomic approach that allows to compare hundreds of proteins simultaneously.

RESULTS

Forty-three proteins exhibiting significant changes (ratio ≥1.5, p<0.05) were characterized, 22 comparing steatosis samples versus control samples and 21 comparing NASH versus control samples. Ten of these proteins were further analyzed by Western blot in tissue samples to confirm the observed changes of protein expression using DIGE. The proteins validated were further tested in serum samples of different cohorts of patients.

CONCLUSIONS AND CLINICAL RELEVANCE

Following this approach we identified two candidate markers, carbamoyl phosphate synthase 1 and 78  kDa glucose-regulated protein, differentially expressed between control and NASH. This proteomics approach demonstrates that DIGE combined with MALDI TOF/TOF and Western blot analysis of tissue and serum samples is a useful approach to identify candidate markers associated with NAFLD, resulting in proteins whose level of expression can be correlated to a disease state.

Role of nuclear factor kappaB in liver health and disease

NF-kappaB (nuclear factor kappaB) is a heterodimeric transcription factor that is constitutively expressed in all cell types and has a central role as a transcriptional regulator in response to cellular stress. In the present review, we discuss the role of NF-kappaB signalling in the maintenance of liver homoeostasis as well as in the pathogenesis of a wide variety of conditions affecting the liver, including viral hepatitis, steatohepatitis, cirrhosis and hepatocellular carcinoma. Much of the current knowledge of NF-kappaB signalling in the liver relates to the canonical pathway, the IKK [IkappaB (inhibitor of kappaB) kinase] complex and the RelA subunit. We explore the weaknesses of the experimental approaches to date and suggest that further work is needed to investigate in detail the discreet functions of each of the Rel subunits in liver physiology and disease.

Reversibility of fibrosis, inflammation, and endoplasmic reticulum stress in the liver of rats fed a methionine-choline-deficient diet

Fatty liver disease has become a health problem related to metabolic syndrome worldwide, although its molecular pathogenesis requires further study. It is also unclear whether advanced fibrosis of steatohepatitis will regress when diet is controlled. The aim of this study was to investigate whether the resolution of fibrosis occurs in steatohepatitis induced by a methionine-choline-deficient diet (MCDD). Manifestation of endoplasmic reticulum (ER) stress in this model was also studied. Nonalcoholic steatohepatitis with advanced fibrosis was induced in rats by feeding them an MCDD for 10 weeks. Instead of MCDD, a methionine-choline control diet (CD) was given for the last 2 weeks to the experimental group. Fibrosis and inflammation were determined by tissue staining. Protein and gene expressions were determined by immunoblotting and quantitative reverse transcription-PCR (RT-PCR), respectively. Expressions of caspase-7, caspase-12, glucose-regulated protein 78 (GRP78), and protein disulfide isomerase were evaluated to clarify the presence of ER stress. Changing the diet from MCDD to CD triggered the reduction of fat in hepatocytes, a decrease in inflammatory gene expression and oxidative stress, and regression of fibrosis accompanied by the disappearance of activated stellate cells and macrophages. Immunohistochemistry, immunoblotting, and RT-PCR analysis all indicated the occurrence of ER stress in steatohepatitis, while it recovered immediately after changing the diet from MCCD to CD. The ratio of hepatocyte proliferation/apoptotis increased significantly during the recovery stage. This simple experiment clearly shows that changing the diet from MCDD to a normal diet (CD) triggers the resolution of hepatic inflammatory and fibrotic reactions and hepatocyte apoptosis, suggesting that MCDD-induced steatohepatitis is also reversible. ER stress appears and disappears in association with the generation and regression of steatohepatitis, respectively, with fibrosis.

Biochemical mechanisms in drug-induced liver injury: certainties and doubts

Drug-induced liver injury is a significant and still unresolved clinical problem. Limitations to knowledge about the mechanisms of toxicity render incomplete the detection of hepatotoxic potential during preclinical development. Several xenobiotics are lipophilic substances and their transformation into hydrophilic compounds by the cytochrome P-450 system results in production of toxic metabolites. Aging, preexisting liver disease, enzyme induction or inhibition, genetic variances, local O(2) supply and, above all, the intrinsic molecular properties of the drug may affect this process. Necrotic death follows antioxidant consumption and oxidation of intracellular proteins, which determine increased permeability of mitochondrial membranes, loss of potential, decreased ATP synthesis, inhibition of Ca(2+)-dependent ATPase, reduced capability to sequester Ca(2+) within mitochondria, and membrane bleb formation. Conversely, activation of nucleases and energetic participation of mitochondria are the main intracellular mechanisms that lead to apoptosis. Non-parenchymal hepatic cells are inducers of hepatocellular injury and targets for damage. Activation of the immune system promotes idiosyncratic reactions that result in hepatic necrosis or cholestasis, in which different HLA genotypes might play a major role. This review focuses on current knowledge of the mechanisms of drug-induced liver injury and recent advances on newly discovered mechanisms of liver damage. Future perspectives including new frontiers for research are discussed.

Pyruvate dehydrogenase kinase isoenzyme 4 (PDHK4) deficiency attenuates the long-term negative effects of a high-saturated fat diet

The hypothesis that PDHK4 (pyruvate dehydrogenase kinase isoenzyme 4) has potential as a target for the treatment of type 2 diabetes was tested by feeding wild-type and PDHK4 knockout mice a high saturated fat diet that induces hyperglycemia, hyperinsulinaemia, glucose intolerance, hepatic steatosis and obesity. Previous studies have shown that PDHK4 deficiency lowers blood glucose by limiting the supply of three carbon gluconeogenic substrates to the liver. There is concern, however, that the increase in glucose oxidation caused by less inhibition of the pyruvate dehydrogenase complex by phosphorylation will inhibit fatty acid oxidation, promote ectopic fat accumulation and worsen insulin sensitivity. This was examined by feeding wild-type and PDHK4 knockout mice a high saturated fat diet for 8 months. Fasting blood glucose levels increased gradually in both groups but remained significantly lower in the PDHK4 knockout mice. Hyperinsulinaemia developed in both groups, but glucose tolerance was better and body weight was lower in the PDHK4 knockout mice. At termination, less fat was present in the liver and skeletal muscle of the PDHK4 knockout mice. Higher amounts of PGC-1alpha [PPARgamma (peroxisome proliferator-activated receptor gamma) coactivator 1alpha] and PPARalpha and lower amounts of fatty acid synthase and acetyl-CoA carboxylase isoenzyme 1 were present in the liver of the PDHK4 knockout mice. These findings suggest PDHK4 deficiency creates conditions that alter upstream signalling components involved in the regulation of lipid metabolism. The findings support the hypothesis that PDHK4 is a viable target for the treatment of type 2 diabetes.