Obesity Liver Disease Research Articles

Liver microRNA transcriptome reveals miR-182 as link between type 2 diabetes and fatty liver disease in obesity

Background:The development of obesity-associated comorbidities such as type 2 diabetes (T2D) and hepatic steatosis has been linked to selected microRNAs in individual studies; however, an unbiased genome-wide approach to map T2D induced changes in the miRNAs landscape in human liver samples, and a subsequent robust identification and validation of target genes are still missing.Methods:Liver biopsies from age- and gender-matched obese individuals with (n=20) or without (n=20) T2D were used for microRNA microarray analysis. The candidate microRNA and target genes were validated in 85 human liver samples, and subsequently mechanistically characterized in hepatic cells as well as by dietary interventions and hepatic overexpression in mice.Results:Here, we present the human hepatic microRNA transcriptome of type 2 diabetes in liver biopsies and use a novel seed prediction tool to robustly identify microRNA target genes, which were then validated in a unique cohort of 85 human livers. Subsequent mouse studies identified a distinct signature of T2D-associated miRNAs, partly conserved in both species. Of those, human-murine miR-182–5 p was the most associated with whole-body glucose homeostasis and hepatic lipid metabolism. Its target gene LRP6 was consistently lower expressed in livers of obese T2D humans and mice as well as under conditions of miR-182–5 p overexpression. Weight loss in obese mice decreased hepatic miR-182–5 p and restored Lrp6 expression and other miR-182–5 p target genes. Hepatic overexpression of miR-182–5 p in mice rapidly decreased LRP6 protein levels and increased liver triglycerides and fasting insulin under obesogenic conditions after only seven days.Conclusions:By mapping the hepatic miRNA-transcriptome of type 2 diabetic obese subjects, validating conserved miRNAs in diet-induced mice, and establishing a novel miRNA prediction tool, we provide a robust and unique resource that will pave the way for future studies in the field. As proof of concept, we revealed that the repression of LRP6 by miR-182–5 p, which promotes lipogenesis and impairs glucose homeostasis, provides a novel mechanistic link between T2D and non-alcoholic fatty liver disease, and demonstrate in vivo that miR-182–5 p can serve as a future drug target for the treatment of obesity-driven hepatic steatosis.Funding:This work was supported by research funding from the Deutsche Forschungsgemeinschaft (KI 1887/2-1, KI 1887/2-2, KI 1887/3-1 and CRC-TR296), the European Research Council (ERC, CoG Yoyo LepReSens no. 101002247; PTP), the Helmholtz Association (Initiative and Networking Fund International Helmholtz Research School for Diabetes; MB) and the German Center for Diabetes Research (DZD Next Grant 82DZD09D1G).

Liver microRNA transcriptome reveals miR-182 as link between type 2 diabetes and fatty liver disease in obesity.

The development of obesity-associated comorbidities such as type 2 diabetes (T2D) and hepatic steatosis has been linked to selected microRNAs in individual studies; however, an unbiased genome-wide approach to map T2D induced changes in the miRNAs landscape in human liver samples, and a subsequent robust identification and validation of target genes are still missing. Liver biopsies from age- and gender-matched obese individuals with (n=20) or without (n=20) T2D were used for microRNA microarray analysis. The candidate microRNA and target genes were validated in 85 human liver samples, and subsequently mechanistically characterized in hepatic cells as well as by dietary interventions and hepatic overexpression in mice. Here, we present the human hepatic microRNA transcriptome of type 2 diabetes in liver biopsies and use a novel seed prediction tool to robustly identify microRNA target genes, which were then validated in a unique cohort of 85 human livers. Subsequent mouse studies identified a distinct signature of T2D-associated miRNAs, partly conserved in both species. Of those, human-murine miR-182-5 p was the most associated with whole-body glucose homeostasis and hepatic lipid metabolism. Its target gene LRP6 was consistently lower expressed in livers of obese T2D humans and mice as well as under conditions of miR-182-5 p overexpression. Weight loss in obese mice decreased hepatic miR-182-5 p and restored Lrp6 expression and other miR-182-5 p target genes. Hepatic overexpression of miR-182-5 p in mice rapidly decreased LRP6 protein levels and increased liver triglycerides and fasting insulin under obesogenic conditions after only seven days. By mapping the hepatic miRNA-transcriptome of type 2 diabetic obese subjects, validating conserved miRNAs in diet-induced mice, and establishing a novel miRNA prediction tool, we provide a robust and unique resource that will pave the way for future studies in the field. As proof of concept, we revealed that the repression of LRP6 by miR-182-5 p, which promotes lipogenesis and impairs glucose homeostasis, provides a novel mechanistic link between T2D and non-alcoholic fatty liver disease, and demonstrate in vivo that miR-182-5 p can serve as a future drug target for the treatment of obesity-driven hepatic steatosis. This work was supported by research funding from the Deutsche Forschungsgemeinschaft (KI 1887/2-1, KI 1887/2-2, KI 1887/3-1 and CRC-TR296), the European Research Council (ERC, CoG Yoyo LepReSens no. 101002247; PTP), the Helmholtz Association (Initiative and Networking Fund International Helmholtz Research School for Diabetes; MB) and the German Center for Diabetes Research (DZD Next Grant 82DZD09D1G).

Elevated Plasma Copeptin Levels Identify the Presence and Severity of Nonalcoholic Fatty Liver Disease in Obesity

Abstract Background Non-alcoholic fatty liver disease is characterized by excessive fat accumulation in the liver with unclear mechanism may be due to epigenetic changes which take place at the transcriptional level without altering the underlying DNA sequence. this epigenetic alternation are involved in regulation of hepatic lipid metabolism, insulin resistance, mitochondrial damage, oxidative stress response, and the release of inflammatory cytokines, all of which have been implicated in the development and progression of NAFLD. Elevated copeptin, a vasopressin marker, is linked to metabolic disease, and obese rats with lowvasopressin concentration had a decreased risk of liver steatosis. Aim and objectives To Detect the elevation of plasma copeptin in obese patients with nonalcoholic fatty liver disease in relation to general population. Subjects and Methods This is A randomized case control cross sectional study, was carried out at internal medicine and gastroenterology department, Ain Shams University hospitals, on 100 patients above 18 years old with Hepatic Steatosis Index (HSI) and NAFLD-Liver Fat Score (LFS), over a period of 6 months. Result There was high statistically significant difference between the studied groups as regard Serum plasma copeptin. Conclusion Our study demonstrates for the first time that copeptin levels predict the presence of biopsy-proven NAFLD in obese individuals, regardless of body adiposity and the coexistence of other metabolic disorders. Studies with longitudinal design are warranted for exploring the possible involvement of AVP/V1aR system in the development and progression of NAFLD.

Integrated omics analysis for characterization of the contribution of high fructose corn syrup to non-alcoholic fatty liver disease in obesity

BackgroundHigh-Fructose Corn Syrup (HFCS), a sweetener rich in glucose and fructose, is nowadays widely used in beverages and processed foods; its consumption has been correlated to the emergence and progression of Non-Alcoholic Fatty Liver Disease (NAFLD). Nevertheless, the molecular mechanisms by which HFCS impacts hepatic metabolism remain scarce, especially in the context of obesity. Besides, the majority of current studies focuses either on the detrimental role of fructose in hepatic steatosis or compare separately the additive impact of fructose versus glucose in high fat diet-induced NAFLD. AimBy engaging combined omics approaches, we sought to characterize the role of HFCS in obesity-associated NAFLD and reveal molecular processes, which mediate the exaggeration of steatosis under these conditions. MethodsHerein, C57BL/6 mice were fed a normal-fat-diet (ND), a high-fat-diet (HFD) or a HFD supplemented with HFCS (HFD-HFCS) and upon examination of their metabolic and NAFLD phenotype, proteomic, lipidomic and metabolomic analyses were conducted to identify HFCS-related molecular alterations of the hepatic metabolic landscape in obesity. ResultsAlthough HFD and HFD-HFCS mice displayed comparable obesity, HFD-HFCS mice showed aggravation of hepatic steatosis, as analysis of the lipid droplet area in liver sections revealed (12,15 % of total section area in HFD vs 22,35 % in HFD-HFCS), increased NAFLD activity score (3,29 in HFD vs 4,86 in HFD-HFCS) and deteriorated hepatic insulin resistance, as compared to the HFD mice. Besides, the hepatic proteome of HFD-HFCS mice was characterized by a marked upregulation of 5 core proteins implicated in de novo lipogenesis (DNL), while an increased phosphatidyl-cholines(PC)/phosphatidyl-ethanolamines(PE) ratio (2.01 in HFD vs 3.04 in HFD-HFCS) was observed in the livers of HFD-HFCS versus HFD mice. Integrated analysis of the omics datasets indicated that Tricarboxylic Acid (TCA) cycle overactivation is likely contributing towards the intensification of steatosis during HFD-HFCS-induced NAFLD. ConclusionOur results imply that HFCS significantly contributes to steatosis aggravation during obesity-related NAFLD, likely deriving from DNL upregulation, accompanied by TCA cycle overactivation and deteriorated hepatic insulin resistance.

Liver Involvement in Individuals with Obesity: A Cross-sectional Study from Western India.

Obesity is a largely neglected health problem in developing countries which leads to additional morbidities including nonalcoholic fatty liver disease (NAFLD), one of the most important causes of chronic liver disease. Central obesity is intricately related to the pathogenesis of the NAFLD, which over time could result in a fiogenic response and end-stage liver disease. We have attempted to study the association of various risk factors and laboratory investigations with the incidence of liver involvement in obese individuals. A cross-sectional study of 210 patients was carried out in a tertiary care center in Western India. Patients above 18 years of age with either general or abdominal obesity were included and their history taking and general and systemic examination was done along with laboratory investigations and ultrasonography for visualize any liver involvement. Age >50 years, female gender, postmenopausal state, sedentary lifestyle, high body mass index (BMI), waist circumference (WC), and neck circumference were all risk factors for liver involvement in obese individuals. Raised C-reactive protein (CRP), serum glutamic-oxaloacetic transaminase (SGOT), triglycerides, low density lipoprotein (LDL), cholesterol, fasting blood sugar (FBS), 2-hour postprandial blood sugar (PP2BS), and low high density lipoprotein (HDL), serum protein, and albumin were significantly associated with liver disease. Patients having high NAFLD fiosis and BMI, aminotransferace ratio and diabetes (BARD) scores, or Metabolic syndrome (MS) was at a higher risk for liver disease. Advancing age, postmenopausal females, and lack of physical activity are risk factors for liver disease in obesity. Raised CRP and SGOT along with impaired lipid profile and glycemic control could be used as markers for fatty liver in obese individuals. MS greatly increases the risk of liver involvement in obese individuals.

Inflammation: The Straw That Broke the NAFLD Liver!

Inflammation: The Straw That Broke the NAFLD Liver!

Iron status influences non-alcoholic fatty liver disease in obesity through the gut microbiome

BackgroundThe gut microbiome and iron status are known to play a role in the pathophysiology of non-alcoholic fatty liver disease (NAFLD), although their complex interaction remains unclear.ResultsHere, we applied an integrative systems medicine approach (faecal metagenomics, plasma and urine metabolomics, hepatic transcriptomics) in 2 well-characterised human cohorts of subjects with obesity (discovery n = 49 and validation n = 628) and an independent cohort formed by both individuals with and without obesity (n = 130), combined with in vitro and animal models. Serum ferritin levels, as a markers of liver iron stores, were positively associated with liver fat accumulation in parallel with lower gut microbial gene richness, composition and functionality. Specifically, ferritin had strong negative associations with the Pasteurellaceae, Leuconostocaceae and Micrococcaea families. It also had consistent negative associations with several Veillonella, Bifidobacterium and Lactobacillus species, but positive associations with Bacteroides and Prevotella spp. Notably, the ferritin-associated bacterial families had a strong correlation with iron-related liver genes. In addition, several bacterial functions related to iron metabolism (transport, chelation, heme and siderophore biosynthesis) and NAFLD (fatty acid and glutathione biosynthesis) were also associated with the host serum ferritin levels. This iron-related microbiome signature was linked to a transcriptomic and metabolomic signature associated to the degree of liver fat accumulation through hepatic glucose metabolism. In particular, we found a consistent association among serum ferritin, Pasteurellaceae and Micrococcacea families, bacterial functions involved in histidine transport, the host circulating histidine levels and the liver expression of GYS2 and SEC24B. Serum ferritin was also related to bacterial glycine transporters, the host glycine serum levels and the liver expression of glycine transporters. The transcriptomic findings were replicated in human primary hepatocytes, where iron supplementation also led to triglycerides accumulation and induced the expression of lipid and iron metabolism genes in synergy with palmitic acid. We further explored the direct impact of the microbiome on iron metabolism and liver fact accumulation through transplantation of faecal microbiota into recipient’s mice. In line with the results in humans, transplantation from ‘high ferritin donors’ resulted in alterations in several genes related to iron metabolism and fatty acid accumulation in recipient’s mice.ConclusionsAltogether, a significant interplay among the gut microbiome, iron status and liver fat accumulation is revealed, with potential significance for target therapies.5HRkabMBtxskC5-wBBcq1wVideo abstract

Assessment of Lifestyle Factors Helps to Identify Liver Fibrosis Due to Non-Alcoholic Fatty Liver Disease in Obesity.

Only some individuals with obesity develop liver fibrosis due to non-alcoholic fatty liver disease (NAFLD-fibrosis). We determined whether detailed assessment of lifestyle factors in addition to physical, biochemical and genetic factors helps in identification of these patients. A total of 100 patients with obesity (mean BMI 40.0 ± 0.6 kg/m2) referred for bariatric surgery at the Helsinki University Hospital underwent a liver biopsy to evaluate liver histology. Physical activity was determined by accelerometer recordings and by the Modifiable Activity Questionnaire, diet by the FINRISK Food Frequency Questionnaire, and other lifestyle factors, such as sleep patterns and smoking, by face-to-face interviews. Physical and biochemical parameters and genetic risk score (GRS based on variants in PNPLA3, TM6SF2, MBOAT7 and HSD17B13) were measured. Of all participants 49% had NAFLD-fibrosis. Independent predictors of NAFLD-fibrosis were low moderate-to-vigorous physical activity, high red meat intake, low carbohydrate intake, smoking, HbA1c, triglycerides and GRS. A model including these factors (areas under the receiver operating characteristics curve (AUROC) 0.90 (95% CI 0.84–0.96)) identified NAFLD-fibrosis significantly more accurately than a model including all but lifestyle factors (AUROC 0.82 (95% CI 0.73–0.91)) or models including lifestyle, physical and biochemical, or genetic factors alone. Assessment of lifestyle parameters in addition to physical, biochemical and genetic factors helps to identify obese patients with NAFLD-fibrosis.

Liver disease in obesity and underweight: the two sides of the coin. A narrative review.

Malnutrition, whether characterized by not enough or too much nutrient intake, is detrimental to the liver. We herein provide a narrative literature revision relative to hepatic disease occurrence in over or undernourished subjects, to shed light on the paradox where both sides of malnutrition lead to similar liver dysfunction and fat accumulation. Medline, EMBASE, and Cochrane Library were searched for publications up to July 2020. Articles discussing the association between both chronic and acute liver pathology and malnutrition were evaluated together with studies reporting the dietary intake in subjects affected by malnutrition. The association between overnutrition and non-alcoholic fatty liver disease (NAFLD) is well recognized, as the beneficial effects of calorie restriction and very low carbohydrate diets. Conversely, the link between undernutrition and liver injury is more complex and less understood. In developing countries, early exposure to nutrient deficiency leads to marasmus and kwashiorkor, accompanied by fatty liver, whereas in developed countries anorexia nervosa is a more common form of undernutrition, associated with liver injury. Weight gain in undernutrition is associated with liver function improvement, whereas no study on the impact of macronutrient distribution is available. We hypothesized a role for very low carbohydrate diets in the management of undernutrition derived liver pathology, in addition to the established one in overnutrition-related NAFLD. Further studies are warranted to update the knowledge regarding undernutrition-related liver disease, and a specific interest should be paid to macronutrient distribution both in the context of refeeding and relative to its role in the development of hepatic complications of anorexia nervosa. Narrative review, Level V.

Lauric Acid versus Palmitic Acid: Effects on Adipose Tissue Inflammation, Insulin Resistance, and Non-Alcoholic Fatty Liver Disease in Obesity.

Coconut oil, rich in medium-chain saturated fatty acids (MCSFA), in particular, lauric acid (LA), is known to exert beneficial metabolic effects. Although LA is the most abundant saturated fatty acid in coconut oil, the specific role of LA in altering obesity-related metabolic disorders remains unknown. Here, we examined the effects of supplementing a high fat (HF) diet with purified LA on obesity-associated metabolic derangements in comparison with palmitic acid (PA), a long-chain saturated fatty acid. Male C57BL/6 mice were fed a control chow diet (CD) or an HF diet supplemented with 3% LA (HF + LA) or PA (HF + PA) for 12 wk. Markers of adipose tissue (AT) inflammation, systemic insulin resistance (IR), and hepatic steatosis, were assessed. The body weight and total fat mass were significantly higher in both HF + LA and HF + PA diet-fed groups compared to CD controls. However, the visceral adipose tissue (VAT) mass was significantly higher (p < 0.001) in HF + LA-fed mice compared to both CD as well as HF + PA-fed mice. Interestingly, markers of AT inflammation were promoted to a lesser extent in HF + LA-fed mice compared to HF + PA-fed mice. Thus, immunohistochemical analysis of VAT showed an increase in MCP-1 and IL-6 staining in HF + PA-fed mice but not in HF + LA-fed mice compared to CD controls. Further, the mRNA levels of macrophage and inflammatory markers were significantly higher in HF + PA-fed mice (p < 0.001) whereas these markers were increased to a lesser extent in HF + LA-fed group. Of note, the insulin tolerance test revealed that IR was significantly increased only in HF + PA-fed mice but not in HF + LA-fed group compared to CD controls. While liver triglycerides were increased significantly in both HF + PA and HF + LA-fed mice, liver weight and plasma markers of liver injury such as alanine aminotransferase and aspartate aminotransferase were increased significantly only in HF + PA-fed mice but not in HF + LA-fed mice. Taken together, our data suggest that although both LA and PA increased AT inflammation, systemic IR, and liver injury, the extent of metabolic derangements caused by LA was less compared to PA in the setting of high fat feeding.

Elevated plasma copeptin levels identify the presence and severity of non-alcoholic fatty liver disease in obesity

IntroductionCopeptin is the stable surrogate marker of vasopressin (VP), which is released in response to elevated plasma osmolality or low blood pressure. Elevated plasma copeptin levels are associated with higher risk of insulin resistance-related disorders, such as type 2 diabetes (T2DM), metabolic syndrome (MS), and cardiovascular disease, and experimental reduction of circulating VP levels is shown to significantly decrease hepatic fat content in obese rats, independently from body adiposity. However, the association between copeptin and non-alcoholic fatty liver disease and steatohepatitis (NAFLD/NASH) in humans has not been explored yet. The aim of this study was to explore the relationship between plasma copeptin and the presence/severity of NAFLD/NASH.MethodsFor this study, we recruited 60 obese patients candidate to bariatric surgery for clinical purposes in which intraoperative liver biopsies were performed for diagnosing NAFLD/NASH. Circulating copeptin levels were also assessed in 60 age- and sex-comparable non-obese individuals without NAFLD at liver ultrasonography. Plasma copeptin was measured by sandwich immunoluminometric assay (Thermo Fisher Scientific).ResultsObese patients with biopsy-proven NAFLD (53%) had significantly higher copeptin levels than both obese individuals without NAFLD and non-obese subjects (ob/NAFLD+ 9.5 ± 4.9; ob/NAFLD− 6.4 ± 2.6; and non-ob/NAFLD− 7.4 ± 5.1 pmol/L; p = 0.004 and p = 0.01 respectively). Plasma copeptin concentration positively correlated with hepatic macro- and micro-vesicular steatosis (r = 0.36, p = 0.026; r = 0.31, p = 0.05), lobular inflammation (r = 0.37, p = 0.024) and significantly increased throughout degrees of NASH severity, as expressed as absence, borderline, and overt NASH at the liver biopsy (r = 0.35, p = 0.01). Greater circulating copeptin predicted the presence of NASH with OR = 1.73 (95% CI = 1.02–2.93) after multivariate adjustment for age, sex, renal function and presence of T2DM and MS components.ConclusionsIncreased plasma copeptin is independently associated with the presence and severity of NAFLD and NASH, pointing to a novel mechanism behind human fatty liver disease potentially modifiable by pharmacological treatment and lifestyle intervention.

Factors Governing Development of Non-Alcoholic Fatty Liver Disease and Insulin Resistance in Obesity

The factors promoting development of non-alcoholic fatty liver disease in patients with obesity and different state of carbohydrate metabolism have been investigated in 43 patients. These included 26 patients with abdominal obesity (BMI = 52.9 ± 7.9 kg/m2) and 17 conditionally healthy donors (control group) without obesity (BMI = 18.9–24.9 kg/m2). Seven (of 17) conditionally healthy persons formed a comparison group that was included to compare the results of study on the levels of tissue-specific expression of HSP70 mRNA. The study of mRNA expression was performed by real-time PCR. Blood serum concentrations of IL-6 and TNF-α were evaluated by the ELISA method. In obese patients with diabetes mellitus type 2 (DM2), a significant increase in the serum level of pro-inflammatory cytokines was found in comparison with the group of patients without DM2 and control. The results of histological examination of liver biopsy specimens in obese patients revealed the most pronounced changes in the group of DM2 patients. Regardless of the stage of nonalcoholic fatty liver disease in obese DM2 patients, there was an increase in the area of fatty inclusions (relative to the group without DM2). The study of the HSP70 gene expression in peripheral blood mononuclear cells revealed a significant increase versus the comparison group. The relationship between the level of the HSP70 gene expression in metabolically active tissues (visceral, subcutaneous adipose tissue and liver) and the serum content of proinflammatory cytokines (IL-6 and TNF-α) found in all obese patients may indicate suppression of HSP70 expression in these tissues under conditions of systemic and local inflammation in obesity.

Factors governing development of nonalcoholic fatty liver disease and insulin resistance in obesity

The factors promoting development of non-alcoholic fatty liver disease in patients with obesity and different state of carbohydrate metabolism have been studied. 43 patients were examined; these included 26 patients with abdominal obesity (BMI=52.9±7.9 kg/m2). The control group consisted of 17 conditionally healthy donors without obesity (BMI=18.9-24.9 kg/m2), seven of them formed a comparison group that was included to compare the results of study on the levels of tissue-specific expression of HSP70 mRNA. The study of mRNA expression was performed by real-time PCR. The concentration of IL-6 and TNF-a was measured in blood serum by the ELISA method. In patients with obesity with diabetes mellitus type 2 (DM2), a significant increase in the serum level of proinflammatory cytokines was found in comparison with the group of patients without DM2 and control. The results of histological examination of liver biopsy specimens in obese patients revealed the most pronounced changes in the group of DM2 patients. Regardless of the stage of nonalcoholic fatty liver disease in obese DM2 patients, an increase in the area of fatty inclusions (relative to the group without type 2 diabetes) was recorded. The study of the HSP70 gene expression in peripheral blood mononuclear cells allowed its significant increase relative to the comparison group. The relationship between the level of expression of the HSP70 gene in metabolically active tissues (visceral, subcutaneous adipose tissue and liver) established in all obese patients with the serum content of proinflammatory cytokines (IL-6 and TNF-a) may indicate suppression of HSP70 expression in these tissues, background of systemic and local inflammation in obesity.

A combination of dietary N-3 fatty acids and a cyclooxygenase-1 inhibitor attenuates nonalcoholic fatty liver disease in mice

We sought to determine whether a combination of purified n-3 fatty acids (n-3) and SC-560 (SC), a cyclooxygenase-1-specific inhibitor, is effective in ameliorating nonalcoholic fatty liver disease in obesity. Female wild-type mice were fed a high-fat and high-cholesterol diet (HF) supplemented with n-3 in the presence or absence of SC. Mice treated with SC alone exhibited no change in liver lipids, whereas n-3-fed mice tended to have lower hepatic lipids. Mice given n-3+SC had significantly lower liver lipids compared with HF controls indicating enhanced lipid clearance. Total and sulfated bile acids were significantly higher only in n-3+SC-treated mice compared with chow diet (CD) controls. Regarding mechanisms, the level of pregnane X receptor (PXR), a nuclear receptor regulating drug/bile detoxification, was significantly higher in mice given n-3 or n-3+SC. Studies in precision-cut liver slices and in cultured hepatoma cells showed that n-3+SC enhanced not only the expression/activation of PXR and its target genes but also the expression of farnesoid X receptor (FXR), another regulator of bile synthesis/clearance, indicating that n-3+SC can induce both PXR and FXR. The mRNA level of FGFR4 which inhibits bile formation showed a significant reduction in Huh 7 cells upon n-3 and n-3+SC treatment. PXR overexpression in hepatoma cells confirmed that n-3 or SC each induced the expression of PXR target genes and in combination had an enhanced effect. Our findings suggest that combining SC with n-3 potentiates its lipid-lowering effect, in part, by enhanced PXR and/or altered FXR/FGFR4 signaling.

Apolipoprotein CIII Overexpression-Induced Hypertriglyceridemia Increases Nonalcoholic Fatty Liver Disease in Association with Inflammation and Cell Death.

Nonalcoholic fatty liver disease (NAFLD) is the principal manifestation of liver disease in obesity and metabolic syndrome. By comparing hypertriglyceridemic transgenic mice expressing apolipoprotein (apo) CIII with control nontransgenic (NTg) littermates, we demonstrated that overexpression of apoCIII, independent of a high-fat diet (HFD), produces NAFLD-like features, including increased liver lipid content; decreased antioxidant power; increased expression of TNFα, TNFα receptor, cleaved caspase-1, and interleukin-1β; decreased expression of adiponectin receptor-2; and increased cell death. This phenotype is aggravated and additional NAFLD features are differentially induced in apoCIII mice fed a HFD. HFD induced glucose intolerance together with increased gluconeogenesis, indicating hepatic insulin resistance. Additionally, the HFD led to marked increases in plasma TNFα (8-fold) and IL-6 (60%) in apoCIII mice. Cell death signaling (Bax/Bcl2), effector (caspase-3), and apoptosis were augmented in apoCIII mice regardless of whether a HFD or a low-fat diet was provided. Fenofibrate treatment reversed several of the effects associated with diet and apoCIII expression but did not normalize inflammatory traits even when liver lipid content was fully corrected. These results indicate that apoCIII and/or hypertriglyceridemia plays a major role in liver inflammation and cell death, which in turn increases susceptibility to and the severity of diet-induced NAFLD.

Genetic polymorphisms in fatty liver disease in HIV positive patients receiving combined antiretroviral therapy (cART)

Background and aims: Hepatic steatosis possibly occurs with any type of antiretroviral therapy (cART). Genome wide association studies have identified 7 single nucleotide polymorphisms (SNPs) predisposing to fatty liver disease in obesity. In this study, we analyzed if the risk of developing fatty liver under cART is associated to single nucleotide polymorphisms in HIV positive patients.

Hepatocyte TRAF3 promotes insulin resistance and type 2 diabetes in mice with obesity.

ObjectiveMetabolic inflammation is believed to promote insulin resistance and type 2 diabetes progression in obesity. TRAF3, a cytoplasmic signaling protein, has been known to mediate/modulate cytokine signaling in immune cells. The goal is to define the metabolic function of hepatic TRAF3 in the setting of obesity.MethodsHepatocyte-specific TRAF3 knockout mice were generated using the loxp/albumin-cre system. Liver TRAF3 was deleted in adult obese mice via Cre adenoviral infection. Both high fat diet-induced and genetic obesity were examined. TRAF3 levels and insulin signaling were measured by immunoblotting. Insulin sensitivity, hepatic glucose production, and glucose metabolism were examined by glucose, insulin, and pyruvate tolerance tests. Hepatic steatosis was examined by Oil red O staining of liver sections and measuring liver triacylglycerol levels.ResultsLiver TRAF3 levels were lower in the fasted states in normal mice, and were aberrantly higher in obese mice and in mice with streptozotocin-induced hyperglycemia. Glucose directly increased TRAF3 levels in primary hepatocytes. Hepatocyte-specific deletion of TRAF3 decreased hyperinsulinemia, insulin resistance, glucose intolerance, and hepatic steatosis in mice with either high fat diet-induced obesity or genetic obesity (ob/ob); conversely, in lean mice, adenovirus-mediated overexpression of TRAF3 in the liver induced hyperinsulinemia, insulin resistance, and glucose intolerance. Deletion of TRAF3 enhanced the ability of insulin to stimulate phosphorylation of Akt in hepatocytes, whereas overexpression of TRAF3 suppressed insulin signaling.ConclusionsGlucose increases the levels of hepatic TRAF3. TRAF3 in turn promotes hyperglycemia through increasing hepatic glucose production, thus forming a glucose-TRAF3 reinforcement loop in the liver. This positive feedback loop may drive the progression of type 2 diabetes and nonalcoholic fatty liver disease in obesity.

Determining the association between adipokine expression in multiple tissues and phenotypic features of non-alcoholic fatty liver disease in obesity.

Objectives:Non-alcoholic fatty liver disease (NAFLD) is an obesity-associated disease, and in obesity adipokines are believed to be involved in the development of NAFLD. However, it is still not clear whether adipokines in the liver and/or adipose tissues can be related to the development of specific characteristics of NAFLD, such as steatosis and inflammation. We aimed to address this question by simultaneously examining the adipokine expression in three tissue types in obese individuals.Methods:We enrolled 93 severely obese individuals with NAFLD, varying from simple steatosis to severe non-alcoholic steatohepatitis. Their expression of 48 adipokines in the liver, visceral and subcutaneous adipose tissue (SAT) was correlated to their phenotypic features of NAFLD. We further determined whether the correlations were tissue specific and/or independent of covariates, including age, sex, obesity, insulin resistance and type 2 diabetes (T2D).Results:The expression of adipokines showed a liver- and adipose tissue-specific pattern. We identified that the expression of leptin, angiopoietin 2 (ANGPT2) and chemerin in visceral adipose tissue (VAT) was associated with different NAFLD features, including steatosis, ballooning, portal and lobular inflammation. In addition, the expression of tumor necrosis factor (TNF), plasminogen activator inhibitor type 1 (PAI-1), insulin-like growth factor 1 (somatomedin C) (IGF1) and chemokine (C-X-C motif) ligand 10 (CXCL10) in the liver tissue and the expression of interleukin 1 receptor antagonist (IL1RN) in both the liver and SAT were associated with NAFLD features. The correlations between ANGPT2 and CXCL10, and NAFLD features were dependent on insulin resistance and T2D, but for the other genes the correlation with at least one NAFLD feature remained significant after correcting for the covariates.Conclusions:Our results suggest that in obese individuals, VAT-derived leptin and chemerin, and hepatic expression of TNF, IGF1, IL1RN and PAI-1 are involved in the development of NAFLD features. Further, functional studies are warranted to establish a causal relationship.

Non Alcoholic Fatty Liver Disease in Obesity

Limited studies have been undertaken to characterize Non-Alcoholic Fatty Liver Disease (NAFLD) in the Indian population. The main objective of our study was to document the prevalence of NAFLD amongst a cohort of obese Indian patients and demonstrate its relationship with other components of the metabolic syndrome. A total of 60 adult obese patients were subjected to a detailed history, clinical exam, anthropometric study and laboratory workup. Focus was on liver function and components of the metabolic syndrome like blood pressure, glycemic status and lipid profile. Subjects enrolled were divided into two groups Group A (n=48), with NAFLD and Group B (n=12) without NAFLD. The two groups were then compared amongst themselves as well as with data from previous similar studies. A comparison of the anthropometric measurements revealed a statistically significant difference between the Body mass index (BMI) and Waist Hip Ratio of the two groups and in the mean triglyceride values between the two groups. Although the mean bilirubin levels measured in the serum were not statistically different the mean levels of SGOT and SGPT in the two groups was found to be statistically significant. On the contrary no significant difference in the values of alkaline phosphatase and synthetic liver functions could be discerned. A statistically highly significant difference in the mean liver span is seen. NAFLD is common in Indian obese populations and is associated with significant differences in anthropometric, clinical, laboratory and ultrasonographic aspects as compared with obese individuals not affected with liver disease.

Review article: non‐alcoholic fatty liver disease in morbidly obese patients and the effect of bariatric surgery

Morbid obesity is strongly associated with non-alcoholic fatty liver disease. The effects of bariatric surgery on liver tests an histological abnormalities after weight loss are controversial. To review the literature on the prevalence of non-alcoholic fatty liver disease in patients with morbid obesity with respect to laboratory and histopathological parameters and the effect of weight loss on these parameters after bariatric surgery. Standard liver tests do not seem to be a sensitive tool for the assessment and follow-up of non-alcoholic fatty liver disease in obesity. In nearly all patients with morbid obesity, histological abnormalities reflecting non-alcoholic fatty liver disease are present. Bariatric surgery in these patients will decrease the grade of steatosis. However, there are some concerns about the effect of bariatric surgery on hepatic inflammation and fibrosis. In particular, older follow-up studies reported negative results as opposed to more recent studies, which also showed improvement in hepatic inflammation and fibrosis. Unfortunately, most studies had limitations because of the selection of patients. Despite limitations in many studies, bariatric surgery seems to be a promising treatment in patients with obesity presenting with non-alcoholic fatty liver disease.