Causes and metabolic consequences of Fatty liver

Effect of Non-Alcoholic Fatty Liver Disease on Estimated Glomerular Filtration Rate Could Be Dependent on Age

There is a gap between the association of non-alcoholic fatty liver disease (NAFLD) and renal function in an apparently healthy population. This study aims to assess whether NAFLD is associated with estimated glomerular filtration rate (eGFR) levels and to understand early changes of eGFR in NAFLD. A cross-sectional study was performed among apparently healthy persons who underwent general health screening including laboratory assessments and hepatic ultrasonography from January 2013 to December 2013 at the First Affiliated Hospital of Zhejiang University, College of Medicine, China. This study included 1,193 subjects with a mean age of 48 years. Prevalence of NAFLD was 31.3%. Mean eGFR was significantly lower in NAFLD than in controls (107 ± 19 mL/min/1.73 m(2) vs. 113 ± 23 mL/min/1.73 m(2), P<0.001). Correlation analysis between eGFR and NAFLD related risk factors revealed an inverse correlation between eGFR levels and some NAFLD risk factors (all P<0.01). All subjects were classified into five phases according to age. Average eGFR levels of NAFLD were lower than controls in three phases for subjects with ≤ 50 years of age (all P<0.05), while there were no significant differences on average eGFR levels between NAFLD and controls in two phases for subjects with >50 years of age (Both P>0.05). The eGFR level is significantly associated with NAFLD and its risk factors in an apparently healthy population. Effects of NAFLD on eGFR could be dependent on age.

[Role of metabolic lipases and lipotoxicity in the development of non-alcoholic steatosis and non-alcoholic steatohepatitis]

Non-alcoholic fatty liver disease (NAFLD) has become the most common liver disease in developed countries, covering a spectrum of pathological conditions ranging from single steatosis to non-alcoholic steatohepatitis, cirrhosis and hepatocellular carcinoma. Its pathogenesis has been often interpreted by the "double-hit" hypothesis, where the lipid accumulation in the liver is followed by proinflammatory mediators inducing inflammation, hepatocellular injury and fibrosis. Nowadays, a more complex model suggests that free fatty acids and their metabolites could be the true lipotoxic agents that contribute to the development of NAFLD and hepatic insulin resistance, suggesting a central role for metabolic lipases in that process.

Activation of aryl hydrocarbon receptor dissociates fatty liver from insulin resistance by inducing fibroblast growth factor 21

The aryl hydrocarbon receptor (AHR), also known as the dioxin receptor, was originally characterized as a xenobiotic receptor that senses xenotoxicants. We investigated the endobiotic and hepatic role of AHR in fatty liver and energy metabolism and identified the endocrine factor that mediates the metabolic function of AHR. Wild-type and liver-specific constitutively activated human AHR transgenic mice were used to investigate the role of AHR in fatty liver and energy homeostasis. Adenovirus expressing short hairpin RNA targeting fibroblast growth factor 21 (FGF21) were used to determine the involvement of FGF21 in the metabolic effect of AHR. We showed that, despite their severe fatty liver, the transgenic mice were protected from diet-induced obesity and type 2 diabetes. We identified the endocrine hormone FGF21 as a mediator for the metabolic benefit of AHR and established FGF21 as a direct transcriptional target of AHR. Interestingly, the transactivation of FGF21 by AHR contributed to both hepatic steatosis and systemic insulin hypersensitivity, both of which were largely abolished upon FGF21 knockdown.

CONCLUSIONS

The AHR-FGF21 endocrine signaling pathway establishes AHR as a pivotal environmental modifier that integrates signals from chemical exposure in the regulation of lipid and energy metabolism.

Low-grade chronic inflammation induces behavioral stereotypy in rats

Schizophrenia is known to be associated with metabolic disturbances including diabetes mellitus, obesity and cardiovascular diseases. A growing body of evidence has suggested abnormal cytokine levels in schizophrenia. In the present study, we explored the effects of low-grade chronic inflammation on behavioral stereotypy in a rat model of non-alcoholic fatty liver disease (NAFLD). In order to induce NAFLD, rats were fed with either water enriched with 30 % fructose or plain tap water for 8 weeks. Following feeding period, behavioral stereotypy was evaluated with apomorphine-induced stereotypy test. Also, levels of tumor necrosis factor alpha (TNF-α), interleukin 2 (IL-2) and nuclear factor kappa B (NF-κB) in the liver and brain tissues were assessed biochemically. Brain homovanilic acid (HVA) was measured to evaluate the dopamine turnover. NAFLD rats showed significantly higher stereotypy score compared to controls (p = 0.016). TNF-α, IL-2, and NF-κB levels were significantly increased in NAFLD rats compared to control group. Brain HVA levels were elevated in NAFLD rats as well (p = 0.008). Moreover, NAFLD group prompted a considerable increase in brain IL-2 immunoexpression (p = 0.005). In conclusion, the present study demonstrates that low-grade chronic inflammation such as NAFLD may enhance apomorphine-induced stereotypic behavior via increasing dopaminergic activity in rats.

Beneficial effects of 2 years of administration of parenteral testosterone undecanoate on the metabolic syndrome and on non-alcoholic liver steatosis and C-reactive protein

BACKGROUND

Elderly men often show a concurrence of a decline of testosterone with attributes of the metabolic syndrome. This study tested the effects of normalization of testosterone.

MATERIALS AND METHODS

A total of 122 hypogonadal men (18-83 years, mean 59.6±8.0 years; n=11<45 years, n=25<55 years, n=53<65 years) were included in the study. Their baseline testosterone levels were between 0.14 and 4.51 ng/mL (n>4.90 ng/mL) and were treated with parenteral testosterone undecanoate for 2 years as the sole intervention (administration at 0 and 6 weeks, and thereafter every 12 weeks).

RESULTS

Plasma testosterone increased from 3.3±1.9 ng/mL to 4.1±1.5 ng/mL (p<0.01) at 3 months, and then stabilized at 6.8±1.3 ng/mL after the first 6 months. There was a remarkable progressive linear decline in body weight, body mass index, and waist circumference over the entire study period. Plasma cholesterol decreased significantly over the first 12 months, and then stabilized. Plasma glucose, triglycerides, low-density lipoprotein cholesterol, and C-reactive protein decreased significantly and high-density lipoprotein cholesterol increased significantly over the 24-month study period in a non-linear manner. There was a significant decrease in aspartate aminotransferase and alanine aminotransferase levels over the first 9 and 12 months, and then values leveled off. Changes in variables were largely correlated with changes in testosterone levels. At baseline, 47 out of 122 subjects fulfilled the metabolic syndrome criteria as defined by the National Cholesterol Education Program (2001); after 2 years of testosterone treatment, this number had declined to 11 out of 122 subjects.

CONCLUSION

With testosterone treatment over 2 years, the most significant improvement of the metabolic syndrome was noted over the first 12 months, but over the following 12 months further improvement was also observed. With regard to safety of testosterone administration to mainly elderly men, a number of safety measures were carried out.

The amelioration of hepatic steatosis by thyroid hormone receptor agonists is insufficient to restore insulin sensitivity in ob/ob mice

Thyroid hormone receptor (TR) agonists have been proposed as therapeutic agents to treat non-alcoholic fatty liver disease (NAFLD) and insulin resistance. We investigated the ability of the TR agonists GC-1 and KB2115 to reduce hepatic steatosis in ob/ob mice. Both compounds markedly reduced hepatic triglyceride levels and ameliorated hepatic steatosis. However, the amelioration of fatty liver was not sufficient to improve insulin sensitivity in these mice and reductions in hepatic triglycerides did not correlate with improvements in insulin sensitivity or glycemic control. Instead, the effects of TR activation on glycemia varied widely and were found to depend upon the time of treatment as well as the compound and dosage used. Lower doses of GC-1 were found to further impair glycemic control, while a higher dose of the same compound resulted in substantially improved glucose tolerance and insulin sensitivity, despite all doses being equally effective at reducing hepatic triglyceride levels. Improvements in glycemic control and insulin sensitivity were observed only in treatments that also increased body temperature, suggesting that the induction of thermogenesis may play a role in mediating these beneficial effects. These data illustrate that the relationship between TR activation and insulin sensitivity is complex and suggests that although TR agonists may have value in treating NAFLD, their effect on insulin sensitivity must also be considered.

Protective effects of farnesoid X receptor (FXR) on hepatic lipid accumulation are mediated by hepatic FXR and independent of intestinal FGF15 signal

BACKGROUND & AIMS

There is a growing evidence that bile acids are involved in the regulation of triglyceride-, cholesterol-homoeostasis and fat absorption. In this study organ-specific Fxr knockout mice were used to further investigate the influence of farnesoid X receptor FXR in lipogenesis.

METHODS

Liver- and intestine-specific Fxr knockout mice were fed a 1% cholesterol diet for 28 days. Histological examination of frozen tissue sections included Sudan III/H&E, BODIPY staining and liver X receptor (LXR) immunohistochemistry. Liver triglycerides, serum cholesterol, serum bile acids and nuclear LXR protein were measured. mRNA expression of several genes involved in bile acid-, cholesterol-homoeostasis and lipogenesis was quantified by real-time PCR.

RESULTS

Hepatic FXR deficiency contributes to lipid accumulation under 1% cholesterol administration which is not observed in intestinal Fxr knockout mice. Strong lipid accumulation, characterized by larger vacuoles could be observed in hepatic Fxr knockout sections, while intestinal Fxr knockout mice show no histological difference to controls. In addition, these mice have the ability to maintain normal serum cholesterol and bile acid levels. Hepatic Fxr knockouts were characterized by elevated triglycerides and bile acid levels. Expression level of LXR was significantly elevated under control and 1% cholesterol diet in hepatic Fxr knockout mice and was followed by concomitant lipogenic target gene induction such as Fas and Scd-1. This protective FXR effect against hepatic lipid accumulation was independent of intestinal Fgf15 induction.

CONCLUSION

These results show that the principal site of protective bile acid signalling against lipid accumulation is located in the liver since the absence of hepatic but not intestinal FXR contributes to lipid accumulation under cholesterol diet.

Comorbidities and Metabolic Derangement of NAFLD

Nonalcoholic fatty liver disease (NAFLD) is an increasingly common cause of chronic liver disease worldwide and is becoming a major public health problem. NAFLD has been recognized as a hepatic manifestation of metabolic syndrome linked with insulin resistance. Growing evidence supports that NAFLD is associated with systemic diseases such as cardiovascular disease (CVD), chronic kidney disease (CKD), type 2 diabetes, obesity, and metabolic syndrome. The majority of deaths in patients with NAFLD come from cardiovascular disease. These findings are strongly attributed to nonalcoholic steatohepatitis (NASH) rather than simple steatosis. NAFLD should be considered not only a liver specific disease but also an early mediator of systemic disease. The underlying mechanisms and pathogenesis of NAFLD with regard to other medical disorders are not yet fully understood. Further investigation is needed for future therapeutic strategies for NAFLD. This review focuses on the relationship between NAFLD and various comorbid diseases and metabolic derangement.

Association of a lifestyle index with MRI-determined liver fat content in a general population study

BACKGROUND

In prior studies, lifestyle indices were associated with numerous disease end points, but the association with fatty liver disease (FLD), a key correlate of cardiometabolic risk, is unknown. The aim was to investigate associations between a lifestyle index with liver fat content.

METHODS

Liver fat was quantified by MRI as liver signal intensity (LSI) in 354 individuals selected from a population-based cohort from Germany. Exposure to favourable lifestyle factors was quantified using an additive score with each factor modelled as a dichotomous trait. Favourable lifestyle factors were defined as waist circumference below 102 (men) or 88 cm (women), physical activity ≥3.5 h/week, never-smoking and a favourable dietary pattern, which was derived to explain liver fat variation. In a cross-sectional study, multivariable adjusted linear and logistic regression was applied to investigate the association between the lifestyle index (range 0-4, exposure) and LSI (modelled as a continuous trait or dichotomised as a FLD indicator variable, respectively).

RESULTS

Individuals with four favourable lifestyle factors (n=9%) had lower LSI values (ß -0.40; 95% CI -0.61 to -0.19) and a lower OR (0.09; 95% CI 0.03 to 0.30) for FLD compared with individuals with zero favourable lifestyle factors (n=10%).

CONCLUSIONS

A healthy lifestyle pattern was associated with less liver fat. Prospective studies are warranted.

Nonalcoholic fatty liver disease and vascular function: cross-sectional analysis in the Framingham heart study

OBJECTIVE

Patients with nonalcoholic fatty liver disease (NAFLD) have an increased risk of cardiovascular disease; however, it is not known whether NAFLD contributes to cardiovascular disease independent of established risk factors. We examined the association between NAFLD and vascular function.

APPROACH AND RESULTS

We conducted a cross-sectional study of 2284 Framingham Heart Study participants without overt cardiovascular disease who had liver fat attenuation measured on computed tomography and who had measurements of vascular function and covariates. We evaluated the association between NAFLD and vascular function using multivariable partial correlations adjusting for age, sex, cohort, smoking, diabetes mellitus, hyperlipidemia, hypertension, body mass index, and visceral adipose tissue. The prevalence of NAFLD in our sample (mean age, 52±12 years; 51.4% women) was 15.3%. In age-, sex-, and cohort-adjusted analyses, greater liver fat was modestly associated with lower flow-mediated dilation (r=-0.05; P=0.02), lower peripheral arterial tonometry ratio (r=-0.20; P<0.0001), higher carotid-femoral pulse wave velocity (r=0.13; P<0.0001), and higher mean arterial pressure (r=0.11; P<0.0001). In multivariable-adjusted models, NAFLD remained associated with higher mean arterial pressure (r=0.06; P=0.005) and lower peripheral arterial tonometry ratio (r=-0.12; P<0.0001). The association between NAFLD and peripheral arterial tonometry ratio persisted after further adjustment for body mass index and visceral adipose tissue.

CONCLUSIONS

For multiple measures of vascular function, the relationship with NAFLD appeared largely determined by shared cardiometabolic risk factors. The persistent relationship with reduced peripheral arterial tonometry response beyond established risk factors suggests that NAFLD may contribute to microvascular dysfunction.

Fetuin-A negatively correlates with liver and vascular fibrosis in nonalcoholic fatty liver disease subjects

BACKGROUND & AIMS

Fetuin-A (α2HS-glycoprotein), a liver secretory glycoprotein, is known as a transforming growth factor (TGF)-β1 signalling inhibitor. Serum fetuin-A concentration is associated with nonalcoholic fatty liver disease (NAFLD) and cardiovascular disease. However, the usefulness of serum fetuin-A as a predictive fibrosis biomarker in NAFLD patients remains unclear. In this study, we investigated the relationship between circulating fetuin-A levels and fibrosis-related markers [platelet count, NAFLD fibrosis score and carotid intima media thickness (IMT)] in subjects with NAFLD.

METHODS

A total of 295 subjects (male, 164; female, 131) who received medical health check-ups were enrolled in this study. NAFLD was diagnosed using abdominal ultrasonography. Serum fetuin-A was measured by ELISA. IMT was assessed using a high-resolution ultrasound scanner. Using recombinant human fetuin-A, we investigated the effects of fetuin-A on hepatic stellate cells, which play a pivotal role in the process of hepatic fibrosis.

RESULTS

Serum fetuin-A concentration was significantly correlated with platelet count (R = 0.19, P < 0.01), NAFLD fibrosis score (R = -0.25, P < 0.01) and mean IMT (R = -0.22, P < 0.01). Multivariate analyses revealed that the fetuin-A concentration is a significant and independent determinant of platelet count, NAFLD fibrosis score and mean IMT. Recombinant fetuin-A suppressed TGF-β1 signalling and fibrosis-related gene expression and increased the expression of TGF-β1 pseudoreceptor bone morphogenic protein and activin membrane-bound inhibitor (BAMBI).

CONCLUSIONS

Serum fetuin-A level is associated with liver/vessel fibrosis-related markers in NAFLD patients. Circulating fetuin-A could be a useful serum biomarker for predicting liver and vascular fibrosis progression in NAFLD patients.

Nonalcoholic fatty liver disease as a potential risk factor of cardiovascular disease

Nonalcoholic fatty liver disease (NAFLD) is the hepatic component of the metabolic syndrome. The aim of this review is to summarize the available data linking NAFLD with cardiovascular disease (CVD). The following topics are reviewed: (a) the clinical evidence linking NAFLD to increased prevalence of CVD; (b) the relationship between NAFLD (which is diagnosed by liver biopsy, serum liver enzymes, or ultrasonography) and incidence of CVD; (c) the mechanism linking NAFLD to CVD and clinical implication; and (d) the potential impact of NAFLD treatment on cardiac complications. CVD dictates the outcome (or outcomes) in patients with NAFLD more frequently and to a greater extent than does the progression of liver disease. NAFLD patients have a higher risk of all-cause death than the general population, mainly because of CVD or liver-related causes. The biologic mechanism linking NAFLD and CVD might be associated with various factors, involving a complex interaction among insulin resistance, oxidative stress, abnormal adipocytokine profile, endothelial dysfunction, lipid abnormalities, and activation of inflammatory cascade. Lifestyle modifications and pharmacotherapy are helpful to treat patients with NAFLD. NAFLD is likely to be associated with an increased risk of CVD, and raises the possibility that NAFLD may not only be a marker but also an early mediator of CVD.

Resolution of NASH with weight loss documented by hepatic MRI

A 57-year-old Asian woman with type 2 diabetes mellitus, hypertension, obesity, dyslipidaemia and history of breast cancer, was referred to the cardiovascular health and lipid centre for evaluation and management of dyslipidaemia and NASH (Non-alcoholic steatohepatitis) in 2010. She originally had a detailed work up at the liver clinic for elevated liver enzymes, with no associated symptoms. Initial hepatic MRI on 22 January 2007 showed diffuse fatty infiltration quantitated at 15%. We counselled her on lifestyle modifications, including dietary measures and exercise, geared toward weight loss. Over the next 2 years, she lost 24.5 lbs; repeat hepatic MRI on 22 December 2011 showed 6% hepatic fat, which is within the normal range. This case demonstrates the efficacy of significant weight loss in the improvement and resolution of NASH. We believe that this is the first case report documenting this through liver MRI.

Television viewing and fatty liver in early midlife. The Cardiovascular Risk in Young Finns Study

INTRODUCTION

Both sedentary behaviour and fatty liver are associated with increased risk of obesity and non-communicable diseases, but their relationship remains unknown. We investigated the relationship of television (TV) viewing time with serum gamma-glutamyltransferase (GGT) and Fatty Liver Index (FLI), and ultrasonographically assessed liver fat.

METHODS

A total of 1,367 adults of the population-based Cardiovascular Risk in Young Finns study (748 women, 619 men, aged 34-49 years) had fasting serum GGT, triglycerides, weight, height, and waist circumference, and self-reported TV time data from 2001, 2007, and 2011. Changes in GGT and FLI, and liver ultrasound images in 2011 were studied in groups with constantly low (≤ 1 h/d), moderate (1-3 h/d), or high (≥ 3 h/d) daily TV time, and in groups with ≥ 1 hour increase/decrease in daily TV time between 2001 and 2011.

RESULTS

Constantly high TV time was associated with higher GGT and FLI (P < 0.02 in both), and 2.3-fold (95% CI 1.2-4.5) increased risk of fatty liver regardless of age, sex, leisure-time and occupational physical activity, energy intake, diet composition, alcohol use, sleep duration, socioeconomic status, and smoking. Adjustment for BMI partly attenuated the associations.

CONCLUSIONS

High TV viewing increases fatty liver risk. It may be one mechanism linking sedentary behaviour with increased cardiometabolic disease risks.

MacroH2A1 isoforms are associated with epigenetic markers for activation of lipogenic genes in fat-induced steatosis

The importance of epigenetic changes in the development of hepatic steatosis is largely unknown. The histone variant macroH2A1 under alternative splicing gives rise to macroH2A1.1 and macroH2A1.2. In this study, we show that the macroH2A1 isoforms play an important role in the regulation of lipid accumulation in hepatocytes. Hepatoma cell line and immortalized human hepatocytes transiently transfected or knocked down with macroH2A1 isoforms were used as in vitro model of fat-induced steatosis. Gene expressions were analyzed by quantitative PCR array and Western blot. Chromatin immunoprecipitation analysis was performed to check the association of histone H3 lysine 27 trimethylation (H3K27me3) and histone H3 lysine 4 trimethylation (H3K4me3) with the promoter of lipogenic genes. Livers from knockout mice that are resistant to lipid deposition despite a high-fat diet were used for histopathology. We found that macroH2A1.2 is regulated by fat uptake and that its overexpression caused an increase in lipid uptake, triglycerides, and lipogenic genes compared with macroH2A1.1. This suggests that macroH2A1.2 is important for lipid uptake, whereas macroH2A1.1 was found to be protective. The result was supported by a high positivity for macroH2A1.1 in knockout mice for genes targeted by macroH2A1 (Atp5a1 and Fam73b), that under a high-fat diet presented minimal lipidosis. Moreover, macroH2A1 isoforms differentially regulate the expression of lipogenic genes by modulating the association of the active (H3K4me3) and repressive (H3K27me3) histone marks on their promoters. This study underlines the importance of the replacement of noncanonical histones in the regulation of genes involved in lipid metabolism in the progression of steatosis.

4Ps medicine of the fatty liver: the research model of predictive, preventive, personalized and participatory medicine-recommendations for facing obesity, fatty liver and fibrosis epidemics

Relationship between adipose tissue and fatty liver, and its possible evolution in fibrosis, is supported by clinical and research experience. Given the multifactorial pathogenesis of non-alcoholic fatty liver disease (NAFLD), treatments for various contributory risk factors have been proposed; however, there is no single validated therapy or drug association recommended for all cases which can stand alone. Mechanisms, diagnostics, prevention and treatment of obesity, fatty liver and insulin resistance are displayed along with recommendations and position points. Evidences and practice can get sustainable and cost-benefit valuable outcomes by participatory interventions. These recommendations can be enhanced by comprehensive research projects, addressed to societal issues and innovation, market appeal and industry development, cultural acceptance and sustainability. The basis of participatory medicine is a greater widespread awareness of a condition which is both a disease and an easy documented and inclusive clue for associated diseases and unhealthy lifestyle. This model is suitable for addressing prevention and useful for monitoring improvement, worsening and adherence with non-invasive imaging tools which allow targeted approaches. The latter include health psychology and nutritional and physical exercise prescription expertise disseminated by continuous medical education but, more important, by concrete curricula for training undergraduate and postgraduate students. It is possible and recommended to do it by early formal teaching of ultrasound imaging procedures and of practical lifestyle intervention strategies, including approaches aimed to healthier fashion suggestions. Guidelines and requirements of research project funding calls should be addressed also to NAFLD and allied conditions and should encompass the goal of training by research and the inclusion of participatory medicine topics. A deeper awareness of ethics of competences in health professionals and the articulation of knowledge, expertise and skills of medical doctors, dieticians, health psychologists and sport and physical exercise graduates are the necessary strategy for detectin a suboptimal health status and achieving realistically beneficial lifestyle changes. “The devil has put a penalty on all things we enjoy in life. Either we suffer in health or we suffer in soul or we get fat” (Albert Einstein); the task of medical research and intervention is to make possible to enjoy life also without things that make sufferance in health and souls and which excessively increase body fat.

Gamma-glutamyl transferase and risk of type II diabetes: an updated systematic review and dose-response meta-analysis

PURPOSE

We assessed the nature of the dose-response relationship between gamma-glutamyl transferase (GGT) levels and risk of incident type II diabetes mellitus (T2DM) in the general population.

METHODS

Systematic review and dose-response meta-analysis of published prospective studies. Relevant studies were identified in a literature search of MEDLINE, EMBASE, and Web of Science databases up to June 2014. We examined a potential nonlinear relationship using restricted cubic splines.

RESULTS

Of the 300 titles reviewed, we included 24 cohort studies with data on 177,307 participants and 11,155 T2DM cases. In pooled analysis of 16 studies with relevant data, there was evidence of a nonlinear association between GGT and T2DM risk in both males (P for nonlinearity = .02) and females (P for nonlinearity = .0005). In a comparison of extreme thirds of baseline levels of GGT, relative risk for T2DM in pooled analysis of all 24 studies was 1.34 (95% confidence interval, 1.27-1.42). There was heterogeneity among the studies (P < .001), which was to a large part explained by blood sample used, study size, degree of confounder adjustment, and quality of studies.

CONCLUSIONS

Circulating level of GGT contributes to an increased risk of T2DM in the general population in a nonlinear dose-response pattern.

Fatty liver largely explains associations of subclinical hypothyroidism with insulin resistance, metabolic syndrome, and subclinical coronary atherosclerosis

BACKGROUND

The association of subclinical hypothyroidism (SCH) with insulin resistance, metabolic syndrome (MS), and coronary atherosclerosis is uncertain.

OBJECTIVE

To investigate the role of increased intrahepatic fat in the association of SCH with insulin resistance, MS, and coronary atherosclerosis.

DESIGN, PATIENTS, AND METHODS

We conducted a cross-sectional study in a sample of 753 subjects (46% males) aged 35-70 years with no history of diabetes, renal, hepatic, thyroid, or coronary heart disease, and were participants of the Genetics of Atherosclerotic Disease study. SCH was defined as a high serum TSH level with normal free thyroxine concentration. Fatty liver (FL), coronary artery calcification (CAC), and abdominal visceral adipose tissue were assessed by computed tomography. Cross-sectional associations of SCH with and without FL, with MS, insulin resistance, and subclinical atherosclerosis defined as a CAC score >0, were examined in logistic regression models.

RESULTS

SCH was observed in 17.7% of the population studied. The prevalence of FL was similar in both euthyroid and SCH subjects (31.8 vs 27.8%, P=0.371). SCH plus FL subjects were heavier and had more metabolic abnormalities compared with SCH plus normal liver subjects. In multivariate-adjusted logistic regression analyses, SCH plus FL was associated with MS (odds ratio (OR): 2.73, 95% CI: 1.26-5.92), insulin resistance (OR: 4.91, 95% CI: 1.63-14.75), and CAC score >0 (OR: 3.05, 95% CI: 1.20-7.76). SCH without FL showed no associations.

CONCLUSION

SCH with FL is associated with increased odds of MS, insulin resistance, and CAC, independent of potential confounders.

Type 2 diabetes as a disease of ectopic fat?

BACKGROUND

Although obesity and diabetes commonly co-exist, the evidence base to support obesity as the major driver of type 2 diabetes mellitus (T2DM), and the mechanisms by which this occurs, are now better appreciated.

DISCUSSION

This review briefly examines several sources of evidence - epidemiological, genetic, molecular, and clinical trial - to support obesity being a causal risk factor for T2DM. It also summarises the ectopic fat hypothesis for this condition, and lists several pieces of evidence to support this concept, extending from rare conditions and drug effects to sex- and ethnicity-related differences in T2DM prevalence. Ectopic liver fat is the best-studied example of ectopic fat, but more research on pancreatic fat as a potential cause of β-cell dysfunction seems warranted. This ectopic fat concept, in turn, broadly fits with the observation that individuals of similar ages can develop diabetes at markedly different body mass indexes (BMIs). Those with risk factors leading to more rapid ectopic fat gain - for example, men (compared with women), certain ethnicities, and potentially those with a family history of diabetes, as well as others with genes linked to a reduced subcutaneous adiposity - are more likely to develop diabetes at a younger age and/or lower BMI than those without.

SUMMARY

Obesity is the major risk factor for T2DM and appears to drive tissue insulin resistance in part via gain of ectopic fat, with the best-studied organ being the liver. However, ectopic fat in the pancreas may contribute to β-cell dysfunction. In line with this observation, rapid resolution of diabetes linked to a preferential and rapid reduction in liver fat has been noted with significant caloric reduction. Whether these observations can help develop better cost-effective and sustainable lifestyle /medical interventions in patients with T2DM requires further study.

Association between noninvasive fibrosis markers and cardio-vascular organ damage among adults with hepatic steatosis

Evidence suggests that advanced fibrosis, as determined by the noninvasive NAFLD fibrosis score (NFS), is a predictor of cardiovascular mortality in individuals with ultrasonography-diagnosed NAFLD. Whether the severity of histology (i.e., fibrosis stage) is associated with more pronounced cardiovascular organ damage is unsettled. In this study, we analyzed the clinical utility of NFS in assessing increased carotid intima-media thickness (cIMT), and left ventricular mass index (LVMI). In this cross-sectional study NFS, cIMT and LVMI were assessed in 400 individuals with ultrasonography-diagnosed steatosis. As compared with individuals at low probability of liver fibrosis, individuals both at high and at intermediate probability of fibrosis showed an unfavorable cardio-metabolic risk profile having significantly higher values of waist circumference, insulin resistance, high sensitivity C-reactive protein (hsCRP), fibrinogen, cIMT, and LVMI, and lower insulin-like growth factor-1 (IGF-1) levels. The differences in cIMT and LVMI remained significant after adjustment for smoking and metabolic syndrome. In a logistic regression model adjusted for age, gender, smoking, and diagnosis of metabolic syndrome, individuals at high probability of fibrosis had a 3.9-fold increased risk of vascular atherosclerosis, defined as cIMT>0.9 mm, (OR 3.95, 95% CI 1.12-13.87) as compared with individuals at low probability of fibrosis. Individuals at high probability of fibrosis had a 3.5-fold increased risk of left ventricular hypertrophy (LVH) (OR 3.55, 95% CI 1.22-10.34) as compared with individuals at low probability of fibrosis. In conclusion, advanced fibrosis, determined by noninvasive fibrosis markers, is associated with cardiovascular organ damage independent of other known factors.

Metabolically healthy obesity, presence or absence of fatty liver, and risk of type 2 diabetes in Japanese individuals: Toranomon Hospital Health Management Center Study 20 (TOPICS 20)

OBJECTIVE

We investigated whether the metabolically healthy obese (MHO) phenotype was associated with an increased risk of the development of diabetes. If so, we aimed to determine what factors could explain this finding.

DESIGN, SETTING, AND PARTICIPANTS

Studied were 8090 Japanese individuals without diabetes. Metabolic health status was assessed by common clinical markers: blood pressure, triglycerides, high-density lipoprotein-cholesterol, and fasting glucose concentrations. The cutoff value for obesity or normal weight (NW) was a body mass index of 25.0 kg/m(2).

RESULTS

The 5-year incidence rate of diabetes was 1.2% (n = 58 of 4749) in metabolically healthy NW (MHNW) individuals, 2.8% (n = 20 of 719) in MHO individuals, 6.0% (n = 102 of 1709) in metabolically abnormal NW individuals, and 10.3% (n = 94 of 913) in metabolically abnormal obese individuals. Although MHO individuals had no or one metabolic factor, 47.8% had ultrasonographic fatty liver (FL). The MHO group had a significantly increased risk of diabetes compared with the MHNW group [multivariate adjusted odds ratio (OR) 2.23 (95% confidence interval [CI] 1.33, 3.75)], but this risk was attenuated after adjustment for FL. Compared with the MHNW/non-FL group, the risk of diabetes in the MHO/non-FL group was not significantly elevated [OR 1.01 (95% CI 0.35, 2.88)]. However, the MHO/FL and MHNW/FL groups had similarly elevated risks of diabetes [OR 4.09 (95% CI 2.20, 7.60) and 3.16 (1.78, 5.62), respectively].

CONCLUSIONS

Almost half of the MHO participants had FL, which partially explained the increased risk of diabetes among the obese phenotypes. The presence of FL should be evaluated to assess whether an individual was actually in a metabolically benign state for the prediction of diabetes.

Non-alcoholic fatty liver disease and obesity: Biochemical, metabolic and clinical presentations

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease in the world. Presentation of the disease ranges from simple steatosis to non-alcoholic steatohepatitis (NASH). NAFLD is a hepatic manifestation of metabolic syndrome that includes central abdominal obesity along with other components. Up to 80% of patients with NAFLD are obese, defined as a body mass index (BMI) > 30 kg/m². However, the distribution of fat tissue plays a greater role in insulin resistance than the BMI. The large amount of visceral adipose tissue (VAT) in morbidly obese (BMI > 40 kg/m²) individuals contributes to a high prevalence of NAFLD. Free fatty acids derived from VAT tissue, as well as from dietary sources and de novo lipogenesis, are released to the portal venous system. Excess free fatty acids and chronic low-grade inflammation from VAT are considered to be two of the most important factors contributing to liver injury progression in NAFLD. In addition, secretion of adipokines from VAT as well as lipid accumulation in the liver further promotes inflammation through nuclear factor kappa B signaling pathways, which are also activated by free fatty acids, and contribute to insulin resistance. Most NAFLD patients are asymptomatic on clinical presentation, even though some may present with fatigue, dyspepsia, dull pain in the liver and hepatosplenomegaly. Treatment for NAFLD and NASH involves weight reduction through lifestyle modifications, anti-obesity medication and bariatric surgery. This article reviews the available information on the biochemical and metabolic phenotypes associated with obesity and fatty liver disease. The relative contribution of visceral and liver fat to insulin resistance is discussed, and recommendations for clinical evaluation of affected individuals is provided.

Nonalcoholic fatty liver disease and the heart in children and adolescents

Over the last two decades, the rise in the prevalence rates of overweight and obesity explains the emergence of nonalcoholic fatty liver disease (NAFLD) as the leading cause of chronic liver disease worldwide. As described in adults, children and adolescents with fatty liver display insulin resistance, glucose intolerance, and dyslipidemia. Thus NAFLD has emerged as the hepatic component of the metabolic syndrome (MetS) and a strong cardiovascular risk factor even at a very early age. Several studies, including pediatric populations, have reported independent associations between NAFLD and markers of subclinical atherosclerosis including impaired flow-mediated vasodilation, increased carotid artery intima-media thickness, and arterial stiffness, after adjusting for cardiovascular risk factors and MetS. Also, it has been shown that NAFLD is associated with cardiac alterations, including abnormal left ventricular structure and impaired diastolic function. The duration of these subclinical abnormalities may be important, because treatment to reverse the process is most likely to be effective earlier in the disease. In the present review, we examine the current evidence on the association between NAFLD and atherosclerosis as well as between NAFLD and cardiac dysfunction in the pediatric population, and discuss briefly the possible biological mechanisms linking NAFLD and cardiovascular changes. We also address the approach to treatment for this increasingly prevalent disease, which is likely to have an important future global impact on the burden of ill health, to prevent not only end-stage liver disease but also cardiovascular disease.

Nonalcoholic fatty liver disease and polycystic ovary syndrome

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in the Western world comprising a spectrum of liver damage from fatty liver infiltration to end-stage liver disease, in patients without significant alcohol consumption. Increased prevalence of NAFLD has been reported in patients with polycystic ovary syndrome (PCOS), one of the most common endocrinopathies in premenopausal women, which has been redefined as a reproductive and metabolic disorder after the recognition of the important role of insulin resistance in the pathophysiology of the syndrome. Obesity, in particular central adiposity and insulin resistance are considered as the main factors related to NAFLD in PCOS. Moreover, existing data support that androgen excess, which is the main feature of PCOS and is interrelated to insulin resistance, may be an additional contributing factor to the development of NAFLD. Although the natural history of NAFLD remains unclear and hepatic steatosis seems to be a relatively benign condition in most patients, limited data imply that advanced stage of liver disease is possibly more frequent in obese PCOS patients with NAFLD. PCOS patients, particularly obese patients with features of the metabolic syndrome, should be submitted to screening for NAFLD comprising assessment of serum aminotransferase levels and of hepatic steatosis by abdominal ultrasound. Lifestyle modifications including diet, weight loss and exercise are the most appropriate initial therapeutic interventions for PCOS patients with NAFLD. When pharmacologic therapy is considered, metformin may be used, although currently there is no medical therapy of proven benefit for NAFLD. Long-term follow up studies are needed to clarify clinical implications and guide appropriate diagnostic evaluation, follow-up protocol and optimal treatment for PCOS patients with NAFLD.

Estrogen receptor ligands ameliorate fatty liver through a nonclassical estrogen receptor/Liver X receptor pathway in mice

Liver X receptor (LXR) activation stimulates triglyceride (TG) accumulation in the liver. Several lines of evidence indicate that estradiol-17β (E2) reduces TG levels in the liver; however, the molecular mechanism underlying the E2 effect remains unclear. Here, we show that administration of E2 attenuated sterol regulatory element-binding protein (SREBP)-1 expression and TG accumulation induced by LXR activation in mouse liver. In estrogen receptor alpha (ERα) knockout (KO) and liver-specific ERα KO mice, E2 did not affect SREBP-1 expression or TG levels. Molecular analysis revealed that ERα is recruited to the SREBP-1c promoter through direct binding to LXR and inhibits coactivator recruitment to LXR in an E2-dependent manner. Our findings demonstrate the existence of a novel liver-dependent mechanism controlling TG accumulation through the nonclassical ER/LXR pathway. To confirm that a nonclassical ER/LXR pathway regulates ERα-dependent inhibition of LXR activation, we screened ERα ligands that were able to repress LXR activation without enhancing ERα transcriptional activity, and, as a result, we identified the phytoestrogen, phloretin. In mice, phloretin showed no estrogenic activity; however, it did reduce SREBP-1 expression and TG levels in liver of mice fed a high-fat diet to an extent similar to that of E2.

CONCLUSION

We propose that ER ligands reduce TG levels in the liver by inhibiting LXR activation through a nonclassical pathway. Our results also indicate that the effects of ER on TG accumulation can be distinguished from its estrogenic effects by a specific ER ligand.

Nonalcoholic fatty liver disease and metabolic syndrome in postmenopausal women

Nonalcoholic fatty liver disease (NAFLD) is considered the most common cause of chronic liver disease in the Western countries. NAFLD includes a spectrum ranging from a simple steatosis to a nonalcoholic steatohepatitis (NASH) which is defined by the presence of inflammatory infiltrate, cellular necrosis, hepatocyte ballooning, and fibrosis and cirrhosis that can eventually develop into hepatocellular carcinoma. Studies emphasize the role of insulin resistance, oxidative stress, pro-inflammatory cytokines, adipokines in the development and progression of NAFLD. It seems to be independently associated with type II diabetes mellitus, increased triglycerides, decreased HDL-cholesterol, abdominal obesity and insulin resistance. These findings are in accordance with the criteria used in the diagnosis of metabolic syndrome (MetS). Here, we will discuss the current knowledge on the epidemiology, pathophysiology and diagnosis of NAFLD and the association of metabolic syndrome in postmenopausal women.

Relationship between sarcopenia and nonalcoholic fatty liver disease: the Korean Sarcopenic Obesity Study

Previous studies have shown that nonalcoholic fatty liver disease (NAFLD) and sarcopenia may share pathophysiological mechanisms, such as insulin resistance, inflammation, vitamin D deficiency, and decreased physical activity. However, their direct relationship has not been investigated. The association between NAFLD and sarcopenia was examined in 452 apparently healthy adults enrolled in the Korean Sarcopenic Obesity Study (KSOS), an ongoing prospective observational cohort study. The liver attenuation index (LAI), which was measured using abdominal computed tomography (CT), was used as a parameter for the diagnosis of NAFLD. Sarcopenia was defined using a skeletal muscle mass index (SMI) [SMI (%) = total skeletal muscle mass (kg) / weight (kg) × 100] that was measured by dual energy X-ray absorptiometry (DXA). After adjusting for age and sex, both SMI and LAI were negatively correlated with the homeostasis model assessment of insulin resistance (HOMA-IR) (P < 0.001) and high sensitivity C-reactive protein (hsCRP) (P < 0.001) as well as brachial-ankle pulse wave velocity (baPWV), an indicator of arterial stiffness. Furthermore, SMI and LAI had positive relationships with high-density lipoprotein (HDL)-cholesterol, but both had a negative relationship with triglyceride, alanine aminotransferase (ALT), and total body fat. In a multiple logistic regression analysis, the odds ratio for NAFLD risk was 5.16 (95% confidence interval [CI] = 1.63-16.33) in the lowest quartile of SMI compared to the highest after adjusting for potential confounding factors.

CONCLUSION

Individuals with lower muscle mass exhibited increased risk of NAFLD. This result may provide a novel insight into the mechanism linking between sarcopenia and NAFLD. (Clinical trial no. NCT01594710.)

Obesity and renal disease: not all fat is created equal and not all obesity is harmful to the kidneys

The prevalence of obesity is increasing worldwide and contributes to many health problems, including kidney disease. Unexpectedly, 10-30% of obese individuals are apparently not at increased risk of metabolic diseases, e.g. type 2 diabetes, cardiovascular disease and risk of renal disease. Their phenotype is labeled 'metabolically healthy obesity'. In the search for mechanisms explaining this unexpected condition, a favourable type of body fat distribution with low insulin resistance and with low subclinical inflammation has been identified. Furthermore, signalling pathways have been found that distinguish between metabolically benign and malignant obesity. In addition, the important roles of fatty acids, adipokines and hepatokines were identified. These factors regulate insulin resistance and subclinical inflammation. Onset and evolution of chronic kidney disease (CKD) are affected by obesity. CKD also increases the risk of insulin resistance and subclinical inflammation, two pathways that play an important role in the pathogenesis of renal malfunction. This brief review summarizes novel insights, specifically how distinct body fat compartments (including perivascular and even renal sinus fat) may have an impact on progression of CKD.

Multiple short bouts of exercise over 12-h period reduce glucose excursions more than an energy-matched single bout of exercise

OBJECTIVE

Long, uninterrupted bouts of sedentary behavior are thought to negatively influence postprandial glucose and insulin concentrations. We examined the effects of a 1-h bout of morning exercise versus intermittent walking bouts of short duration on glucose excursions and insulin secretion over 12-h.

MATERIALS/METHODS

Eleven young, obese individuals (18-35 years, BMI>30kg/m(2)) with impaired glucose tolerance were studied on three 12-h study days: 1) sedentary behavior (SED); 2) sedentary behavior with 1-h morning exercise (EX) at 60%-65% VO2peak; and 3) sedentary behavior with 12-hourly, 5-min intervals of exercise (INT) at 60%-65% VO2peak. Meals (1046kJ/meal) were provided every 2-h. Blood samples were collected every 10 min and measured for glucose, insulin, and c-peptide concentrations.

RESULTS

Glucose iAUC (12-h) was attenuated in the INT and SED conditions compared to the EX condition (P<0.05). Glucose concentrations were higher in the EX compared to the SED condition for ~150min (20% of the study day), and comparison of the EX-INT study days revealed that glucose concentrations were greater for~240min (~1/3 of the 12-hday). In the SED condition, the 12-h insulin iAUC was ~15% higher (P<0.05) compared to the INT and EX conditions. Insulin production rate was found to increase ~20% with INT exercise vs. the SED and EX condition (P<0.05).

CONCLUSIONS

Short, frequent periods of exercise attenuated glucose excursions and insulin concentrations in obese individuals to a greater degree than an equal amount of exercise performed continuously in the morning.

Review article: the endocannabinoid system in liver disease, a potential therapeutic target

BACKGROUND

Endocannabinoids are a family of potent lipid-soluble molecules, acting on the cannabinoid (CB) receptors that mediate the effects of marijuana. The CB receptors, endocannabinoids and the enzymes involved in their synthesis and degradation are located in the brain and peripheral tissues, including the liver.

AIMS

To review the current understanding of the role of the endocannabinoid system in liver disease-associated pathophysiological conditions, and drugs targeting the endocannabinoid system as therapy for liver disease.

METHODS

Original articles and reviews were used to summarise the relevant pre-clinical and clinical research findings relating to this topic.

RESULTS

The endocannabinoid system as a whole plays an important role in liver diseases (i.e. non-alcoholic liver disease, alcoholic liver disease, hepatic encephalopathy and autoimmune hepatitis) and related pathophysiological conditions (i.e. altered hepatic haemodynamics, cirrhotic cardiomyopathy, metabolic syndrome and ischaemia/reperfusion disease). Pharmacological targeting of the endocannabinoid system has had success as treatment for patients with liver disease, but adverse events led to withdrawal of marketing approval. However, there is optimism over novel therapeutics targeting the endocannabinoid system currently in the pre-clinical stage of development.

CONCLUSIONS

The endocannabinoid system plays an important role in the pathophysiology of liver disease and its associated conditions. While some drugs targeting the endocannabinoid system have deleterious neurological adverse events, there is promise for a newer generation of therapies that do not cross the blood-brain barrier.

Immunological and molecular basis of nonalcoholic steatohepatitis and nonalcoholic fatty liver disease

The prevalence of nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) is rising worldwide with the increasing incidence of obesity, Type 2 diabetes mellitus and metabolic syndrome. NASH is currently one of the most common indications of liver transplantation in the United States. The immune system plays a major role in the pathogenesis of NAFLD/NASH. The metabolic changes, associated with obesity and metabolic syndrome, induce immunological responses resulting in NAFLD and further aggravation of the metabolic derangement in a feed-forward loop. Genetic and endocrine factors modulate the immunological and metabolic responses and determine the pathophysiological features of NAFLD. Histologically, NAFLD is a spectrum that ranges from simple hepatic steatosis to severe steatohepatitis, liver cirrhosis and/or hepatocellular carcinoma. Liver cirrhosis and hepatocellular carcinoma are responsible for the morbidity and mortality of the disease. This article is a critical evaluation of our current knowledge of the immunological and molecular basis of the disease.

Liver fat accumulation is associated with reduced hepatic insulin extraction and beta cell dysfunction in healthy older individuals

BACKGROUND

There is a well-established association between type 2 diabetes and non-alcoholic fatty liver disease (NAFLD) secondary to excess accumulation of intrahepatic lipid (IHL), but the mechanistic basis for this association is unclear. Emerging evidence suggests that in addition to being associated with insulin resistance, NAFLD may be associated with relative beta-cell dysfunction. We sought to determine the influence of liver fat on hepatic insulin extraction and indices of beta-cell function in a cohort of apparently healthy older white adults.

METHODS

We performed a cross-sectional analysis of 70 healthy participants in the Hertfordshire Physical Activity Trial (39 males, age 71.3 ± 2.4 years) who underwent oral glucose tolerance testing with glucose, insulin and C-Peptide levels measured every 30 minutes over two hours. The areas under the concentration curve for glucose, insulin and C-Peptide were used to quantify hepatic insulin extraction (HIE), the insulinogenic index (IGI), the C-Peptide increment (CGI), the Disposition Index (DI) and Adaptation Index (AI). Visceral fat was quantified with magnetic resonance (MR) imaging and IHL with MR spectroscopy. Insulin sensitivity was measured with the Oral Glucose Insulin Sensitivity (OGIS) model.

RESULTS

29 of 70 participants (41%) exceeded our arbitrary threshold for NAFLD, i.e. IHL >5.5%. Compared to those with normal IHL, those with NAFLD had higher weight, BMI, waist and MR visceral fat, with lower insulin sensitivity and hepatic insulin extraction. Alcohol consumption, age, HbA1c and alanine aminotransferase (ALT) levels were similar in both groups. Insulin and C-Peptide excursions after oral glucose loading were higher in the NAFLD group, but the CGI and AI were significantly lower, indicating a relative defect in beta-cell function that is only apparent when C-Peptide is measured and when dynamic changes in glucose levels and also insulin sensitivity are taken into account. There was no difference in IGI or DI between the groups.

CONCLUSIONS

Although increased IHL was associated with greater insulin secretion, modelled parameters suggested relative beta-cell dysfunction with NAFLD in apparently healthy older adults, which may be obscured by reduced hepatic insulin extraction. Further studies quantifying pancreatic fat content directly and its influence on beta cell function are warranted.

TRIAL REGISTRATION

ISRCTN60986572.

Cinnamon extract improves insulin sensitivity in the brain and lowers liver fat in mouse models of obesity

Objectives

Treatment of diabetic subjects with cinnamon demonstrated an improvement in blood glucose concentrations and insulin sensitivity but the underlying mechanisms remained unclear. This work intends to elucidate the impact of cinnamon effects on the brain by using isolated astrocytes, and an obese and diabetic mouse model.

Methods

Cinnamon components (eugenol, cinnamaldehyde) were added to astrocytes and liver cells to measure insulin signaling and glycogen synthesis. Ob/ob mice were supplemented with extract from cinnamomum zeylanicum for 6 weeks and cortical brain activity, locomotion and energy expenditure were evaluated. Insulin action was determined in brain and liver tissues.

Results

Treatment of primary astrocytes with eugenol promoted glycogen synthesis, whereas the effect of cinnamaldehyde was attenuated. In terms of brain function in vivo, cinnamon extract improved insulin sensitivity and brain activity in ob/ob mice, and the insulin-stimulated locomotor activity was improved. In addition, fasting blood glucose levels and glucose tolerance were greatly improved in ob/ob mice due to cinnamon extracts, while insulin secretion was unaltered. This corresponded with lower triglyceride and increased liver glycogen content and improved insulin action in liver tissues. In vitro, Fao cells exposed to cinnamon exhibited no change in insulin action.

Conclusions

Together, cinnamon extract improved insulin action in the brain as well as brain activity and locomotion. This specific effect may represent an important central feature of cinnamon in improving insulin action in the brain, and mediates metabolic alterations in the periphery to decrease liver fat and improve glucose homeostasis.

Aggravation of nonalcoholic steatohepatitis by moderate alcohol consumption is associated with decreased SIRT1 activity in rats

Chronic alcohol intake decreases adiponectin and sirtuin 1 (SIRT1) expressions, both of which have been implicated in various biological processes including inflammation, apoptosis and metabolism. We have previously shown that moderate consumption of alcohol aggravates liver inflammation and apoptosis in rats with pre-existing nonalcoholic steatohepatitis (NASH). This study investigated whether moderate alcohol intake alters SIRT1 activity, adiponectin/Adiponectin receptor (AdipoR)-related signaling and lipid metabolism in a pre-existing NASH status. Sprague-Dawley rats were fed with a high-fat diet (71% energy from fat) for 6 weeks to induce NASH then subsequently divided into 2 sub-groups: fed either a modified high-fat diet (HFD, 55% energy from fat) or a modified high-fat alcoholic diet (HFA, 55% energy from fat and 16% energy from ethanol) for an additional 4 weeks. We observed in comparison to HFD group, HFA increased hepatic nuclear SIRT1 protein but decreased its deacetylase activity. SREBP-1c protein expression and FAS mRNA levels were significantly upregulated, while DGAT1/2 and CPT-I mRNA levels were downregulated in the livers of HFA compared to HFD. Although hepatic AdipoR1 decreased, HFA did not alter AdipoR2 and their downstream signaling. There were no significant changes in plasma adiponectin and free fatty acids (FFA), as well as adiponectin expression in adipose tissue between the two groups. The present study indicates that suppression in SIRT1 deacetylase activity contributes to alcohol-exacerbated hepatic inflammation and apoptosis in rats with pre-existing NASH. In addition, moderate alcohol intake did not modulate adiponectin/AdipoR signaling axis in this model.

Association between noninvasive fibrosis markers and chronic kidney disease among adults with nonalcoholic fatty liver disease

Evidence suggests that nonalcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) are associated with an increased risk of chronic kidney disease (CKD). In this study we aimed to evaluate whether the severity of liver fibrosis estimated by NAFLD fibrosis score is associated with higher prevalence of CKD in individuals with NAFLD. To this end NAFLD fibrosis score and estimated glomerular filtration rate (eGFR) were assessed in 570 White individuals with ultrasonography-diagnosed NAFLD. As compared with subjects at low probability of liver fibrosis, individuals at high and intermediate probability showed an unfavorable cardio-metabolic risk profile having significantly higher values of waist circumference, insulin resistance, high sensitivity C-reactive protein, fibrinogen, uric acid and lower insulin-like growth factor-1 levels. Individuals at high and intermediate probability of liver fibrosis have lower eGFR after adjustment for gender, smoking, glucose tolerance status, homeostasis model assessment index of insulin resistance (HOMA-IR index), diagnosis of metabolic syndrome, statin therapy, anti-diabetes and anti-hypertensive treatments (P = 0.001). Individuals at high probability of liver fibrosis had a 5.1-fold increased risk of having CKD (OR 5.13, 95%CI 1.13–23.28; P = 0.03) as compared with individuals at low probability after adjustment for age, gender, and BMI. After adjustment for glucose tolerance status, statin therapy, and anti-hypertensive treatment in addition to gender, individuals at high probability of liver fibrosis had a 3.9-fold increased risk of CKD (OR 3.94, 95%CI 1.11–14.05; P = 0.03) as compared with individuals at low probability. In conclusion, advanced liver fibrosis, determined by noninvasive fibrosis markers, is associated with CKD independently from other known factors.

Association of fatty liver disease with nonfatal cardiovascular events in patients undergoing maintenance hemodialysis

BACKGROUND/AIMS

The prevalence of cardiovascular (CV) disease in patients undergoing maintenance hemodialysis (HD) is reportedly higher than that in healthy individuals. In the present study, we aimed to investigate whether ultrasonographically documented fatty liver disease (FLD) is an independent risk factor for nonfatal CV events in patients undergoing HD.

METHODS

A retrospective cohort study was conducted in a medical center in southern Taiwan. The medical records of 490 patients undergoing HD who were enrolled between July 1998 and October 2012 were screened. Finally, 278 patients who had undergone hepatic ultrasonography and had available data were recruited in the present study. The patients included 130 men and 148 women; their mean age was 59.9 years. The primary endpoint was nonfatal CV events in the observation period. The comparable data included epidemiological, hematological, and biochemical profiles. A time-dependent statistical method was used to analyze the associated factors.

RESULTS

The prevalence of nonfatal CV events was significantly increased in the patients with FLD compared with those without FLD (CV events: 32 vs. 18%, respectively; p = 0.008). After adjusting for associated risk factors (sex, age, body mass index, smoking, diabetes, hypertension, dyslipidemia, and Kt/V), multivariate analyses identified FLD (CV events: hazard ratio 2.84, 95% confidence interval 1.52-5.28, p = 0.001), advanced age, and diabetes to be independently associated with nonfatal CV events.

CONCLUSION

The study suggests that FLD was an independent risk factor for nonfatal CV events in patients undergoing maintenance HD.

Nonalcoholic fatty liver disease, hepatic insulin resistance, and type 2 diabetes

Nonalcoholic fatty liver disease (NAFLD), hepatic insulin resistance, and type 2 diabetes are all strongly associated and are all reaching epidemic proportions. Whether there is a causal link between NAFLD and hepatic insulin resistance is controversial. This review will discuss recent studies in both humans and animal models of NAFLD that have implicated increases in hepatic diacylglycerol (DAG) content leading to activation of novel protein kinase Cϵ (PKCϵ) resulting in decreased insulin signaling in the pathogenesis of NAFLD-associated hepatic insulin resistance and type 2 diabetes. The DAG-PKCϵ hypothesis can explain the occurrence of hepatic insulin resistance observed in most cases of NAFLD associated with obesity, lipodystrophy, and type 2 diabetes.

The interactions of nonalcoholic fatty liver disease and cardiovascular diseases

A complex interaction among metabolic factors, adipose tissue lipolysis, oxidative stress, and insulin resistance results in a deleterious process that may link nonalcoholic fatty liver disease (NAFLD) with severe cardiovascular (CV) outcomes. Patients with NAFLD are at higher risk of atherosclerosis, new onset of CV events, and overall mortality. The strong association between NAFLD and CV disease should affect clinical practice, with screening and surveillance of patients with NAFLD. This review discusses the data linking these major diseases.

Assisted reproductive technologies impair the expression and methylation of insulin-induced gene 1 and sterol regulatory element-binding factor 1 in the fetus and placenta

OBJECTIVE

To evaluate the cholesterol metabolism linked to assisted reproductive technology (ART) by analyzing the expression levels and DNA methylation patterns of the insulin-induced gene (INSIG), sterol regulatory element-binding protein (SREBP), and SREBP cleavage-activating protein in the fetus and placenta.

DESIGN

Experimental research study.

SETTING

An IVF center, university-affiliated teaching hospital.

PATIENT(S)

Four patients groups were recruited: pregnancies after IVF/intracytoplasmic sperm injection (ICSI) (n = 55), natural pregnancies (n = 40), multifetal reduction after IVF/ICSI (n = 56), and multifetal reduction after controlled ovarian hyperstimulation (COH) (n = 42).

INTERVENTION(S)

Expression and DNA methylation of INSIG-SREBP- SREBP cleavage-activating protein in the fetus and placenta samples were determined.

MAIN OUTCOME MEASURE(S)

The expression and DNA methylation patterns were tested by real-time quantitative polymerase chain reaction (PCR) and pyrosequencing.

RESULT(S)

In the ICSI treatment group, significantly higher levels of triglycerides and apolipoprotein-B were observed in cord blood compared with controls. Meanwhile, in ICSI-conceived fetuses, the expression of INSIG1 was significantly higher, and methylation rates were lower, than in the IVF and control groups. Furthermore, in the placenta, the INSIG1 and SREBF1 transcripts were also significantly higher with lower methylation rates in the ICSI group than in the IVF and control groups.

CONCLUSION(S)

Our results indicated that the dysregulation of INSIG1 and SREBF1 caused by ART were observed not only in the fetus but also in the placenta, primarily in the ICSI group. However, the long-term sequelae of this dysregulation should be closely followed.

Lifestyle intervention involving calorie restriction with or without aerobic exercise training improves liver fat in adults with visceral adiposity

OBJECTIVE

To evaluate the effect of calorie restriction-induced weight loss with or without aerobic exercise on liver fat.

METHODS

Thirty-three adults with visceral adiposity were divided into calorie restriction (CR; n = 18) or CR and aerobic exercise (CR + Ex; n = 15) groups. Target energy intake was 25 kcal/kg of ideal body weight. The CR + Ex group had a targeted exercise time of 300 min/wk or more at lactate threshold intensity for 12 weeks.

RESULTS

Reductions in body weight (CR, -5.3 ± 0.8 kg; CR + Ex, -5.1 ± 0.7 kg), fat mass (CR, -4.9 ± 0.9 kg; CR + Ex, -4.4 ± 0.6 kg), and visceral fat (CR, -24 ± 5 cm2; CR + Ex, -37 ± 5 cm2) were not statistically different between groups. Liver fat decreased significantly in both groups, with no difference between groups. Change in maximal oxygen uptake was significantly greater in the CR + Ex group than in the CR group (CR, -0.7 ± 0.7 mL/kg/min; CR + Ex, 2.9 ± 1.0 mL/kg/min).

CONCLUSION

Both CR and CR + Ex resulted in an improved reduction in liver fat; however, there was no additive effect of exercise training.

Elevated 1 h postload plasma glucose levels identify adults with normal glucose tolerance but increased risk of non-alcoholic fatty liver disease

OBJECTIVE

To determine the ability of the proposed diagnostic value of a 1-h OGTT glucose ≥155mg/dL to identify individuals with non-alcoholic fatty liver disease (NAFLD) diagnosed by ultrasonography in a cohort of adult white individuals.

DESIGN

The study group comprised 710 white individuals participating to the CATAnzaro MEtabolic RIsk factors (CATAMERI) Study, a cross-sectional study assessing cardio-metabolic risk factors in individuals carrying at least one risk factor including dysglycemia, overweight/obesity, hypertension, dyslipidemia. a 75 g oral Oral Glucose Tolerance Test (OGTT) was performed with 0, 30, 60, 90 and 120 min sampling for plasma glucose and insulin measurements. Cardio-metabolic risk factors including alanine aminotransferase (ALT), aspartate aminotransferase (AST), and gamma-glutamyltransferase (GGT) were assessed in the whole cohort.

RESULTS

Of the 710 participants examined, 295 had normal glucose tolerance (NGT) with 1-hour post-load plasma glucose <155 mg/dL (NGT 1h-low), 109 individuals had NGT 1h-high, 104 had isolated impaired fasting glucose (IFG), and 202 had impaired glucose tolerance (IGT). As compared with NGT 1h-low, NGT 1h-high and IGT subjects exhibited significantly higher body mass index (BMI), triglycerides, high sensitivity C reactive protein, ALT, GGT, and hepatic insulin resistance (IR), assessed by the liver IR index, as well as lower high density lipoprotein, and insulin-like growth factor-1 (IGF-1) levels. In a logistic regression analysis adjusted for age, gender, and BMI, NGT 1h-high participants had a 1.5-fold increased risk of having NAFLD and an even increased risk was observed in subjects with IGT (1.8-fold), but not in the isolated IFG group (1.01-fold).

CONCLUSIONS

These data suggest that the value of a 1-hour OGTT glucose ≥155 mg/dL may be helpful to identify a subset of NGT individuals at risk for NAFLD.

Association of hepatic insulin resistance indexes to nonalcoholic fatty liver disease and related biomarkers

BACKGROUND AND AIMS

Nonalcoholic fatty liver disease (NAFLD) is linked with insulin resistance, however, if it is differentially associated with surrogate hepatic insulin resistance indexes is still undefined. We examined the relationship between these indexes, NAFLD and its related biomarkers (alanine aminotransferase [ALT], aspartate aminotransferase [AST], gamma-glutamyltransferase [GGT], alkaline phosphatase [ALK], high-sensitive C reactive protein [hsCRP], insulin-like growth factor-1 [IGF-1]).

METHODS AND RESULTS

473 Caucasians subjects underwent liver ultrasonography and oral glucose tolerance tests; homeostasis model assessment (HOMA), glucose(0-30) (area under the curve [AUC]) × insulin(0-30) (AUC) and liver insulin resistance (liver IR) indexes were computed. Liver IR index correlated more strongly than HOMA with GGT, ALK, hsCRP, ALT and AST and more strongly than glucose(0-30) (AUC) × insulin(0-30) (AUC) index with ALT, AST, GGT, ALK, hsCRP, and IGF-1. The ability of these indexes to identify NAFLD was evaluated by the area under the ROC curve; the ROC AUC for liver IR index was higher (0.733) than the ones for HOMA (0.685) and glucose(0-30) (AUC) × insulin(0-30) (AUC) (0.663) indexes. In a logistic regression model subjects in the highest quartile of the three indexes had a higher risk of having NAFLD than those in the lowest quartile (9.85-, 5.12- or 3.99-fold higher for liver IR index, HOMA, glucose(0-30) (AUC) × insulin(0-30) (AUC) index respectively).

CONCLUSIONS

we documented significant cross-sectional associations of NAFLD and liver biomarkers with three validated indexes of hepatic insulin resistance, with liver IR index showing the stronger correlation.

Long-lasting improvements in liver fat and metabolism despite body weight regain after dietary weight loss

OBJECTIVE

Weight loss reduces abdominal and intrahepatic fat, thereby improving metabolic and cardiovascular risk. Yet, many patients regain weight after successful diet-induced weight loss. Long-term changes in abdominal and liver fat, along with liver test results and insulin resistance, are not known.

RESEARCH DESIGN AND METHODS

We analyzed 50 overweight to obese subjects (46 ± 9 years of age; BMI, 32.5 ± 3.3 kg/m2; women, 77%) who had participated in a 6-month hypocaloric diet and were randomized to either reduced carbohydrates or reduced fat content. Before, directly after diet, and at an average of 24 (range, 17-36) months follow-up, we assessed body fat distribution by magnetic resonance imaging and markers of liver function and insulin resistance.

RESULTS

Body weight decreased with diet but had increased again at follow-up. Subjects also partially regained abdominal subcutaneous and visceral adipose tissue. In contrast, intrahepatic fat decreased with diet and remained reduced at follow-up (7.8 ± 9.8% [baseline], 4.5 ± 5.9% [6 months], and 4.7 ± 5.9% [follow-up]). Similar patterns were observed for markers of liver function, whole-body insulin sensitivity, and hepatic insulin resistance. Changes in intrahepatic fat und intrahepatic function were independent of macronutrient composition during intervention and were most effective in subjects with nonalcoholic fatty liver disease at baseline.

CONCLUSIONS

A 6-month hypocaloric diet induced improvements in hepatic fat, liver test results, and insulin resistance despite regaining of weight up to 2 years after the active intervention. Body weight and adiposity measurements may underestimate beneficial long-term effects of dietary interventions.

Non-alcoholic fatty liver disease independently predicts prediabetes during a 7-year prospective follow-up

BACKGROUND & AIMS

Non-alcoholic fatty liver disease (NAFLD) is suspected to confer an increased risk for developing type 2 diabetes (DM). However, only a few prospective studies evaluated NAFLD as a predictor for DM, most did not adjust for the full range of potential cofounders and none used an objectively quantified degree of steatosis. Our aim was to evaluate the independent role of NAFLD in predicting the development of pre-DM in a 7-year prospective follow-up of healthy volunteers.

METHODS

A prospective cohort of a subsample of the Israeli National Health Survey evaluated at baseline and after 7 years by identical protocols. Metabolic parameters and ultrasonographic evidence of NAFLD were evaluated in 213 subjects, without known liver disease or history of alcohol abuse. Exclusion criteria were pre-DM at the baseline survey. Steatosis was quantified by ultrasound with the hepato-renal ultrasound index (HRI).

RESULTS

The study included 141 volunteers (mean age 48.78 ± 9.68, 24.82% with NAFLD) without pre-DM/DM at baseline. Both NAFLD on regular US (OR=2.93, 1.02-8.41 95%CI) and HRI (OR=7.87, 1.83-33.82) were independent predictors for the development of pre-DM, adjusting for age, gender, BMI, family history of DM, baseline insulin, adiponectin and glucose. Further adjustment for physical activity and dietary intake did not weaken the association. Furthermore, NAFLD was a stronger predictor for pre-DM than the metabolic syndrome. Subjects with both NAFLD and glucose ≥89 had 93.3% incidence rate of pre-DM.

CONCLUSION

Non-alcoholic fatty liver disease is a strong and independent risk factor for pre-DM in the general adult population; thus, NAFLD patients should be classified as a population at risk.

Carbohydrate quality and quantity affect glucose and lipid metabolism during weight regain in healthy men

In this controlled, parallel-group feeding trial, we examined the impact of carbohydrate (CHO) intake and glycemic index (GI) on glucose and lipid metabolism during refeeding after weight loss. Healthy men (n = 32 total, age: 25.5 ± 3.9 y, BMI: 23.5 ± 2.0 kg/m2) overconsumed diets containing either 50% or 65% CHO for 1 wk (+50% of energy requirements) and then underwent 3 wk of calorie restriction (CR; -50%) followed by 2 wk of overconsuming (refeeding, +50%) the same diet but with either a low or high GI (40 vs.70 during CR, 41 vs.74 during refeeding) so that glycemic load (GL; dietary CHO content x GI) differed between groups during all phases. Glucose profiles were assessed by continuous interstitial glucose monitoring, insulin sensitivity (IS) by fasting blood sampling, oral glucose tolerance test (OGTT) and hyperinsulinemic-euglycemic clamp, and liver fat by MRI. Daytime area under the curve-glucose during refeeding was higher with high compared with low GI (P = 0.01) and 65% compared with 50% CHO intake (P = 0.05) and correlated with dietary GL (r = 0.71; P < 0.001). IS increased with CR and decreased again with refeeding in all groups. The decrease in OGTT-derived IS was greater with high- than with low-GI diets (-41 vs. -15%; P-interaction = 0.01) and correlated with dietary GL during refeeding (r = -0.51; P < 0.01). Serum triglycerides (TGs) and liver fat also improved with CR (-17 ± 38 mg/dL and -1.1 ± 1.3%; P < 0.05 and <0.001) and increased again with refeeding (+48 ± 48 mg/dL and +2.2 ± 1.6%; P < 0.001). After refeeding, serum TGs and liver fat were elevated above baseline values with 65% CHO intake only (+59.9 ± 37.5 mg/dL and +1.1 ± 1.7%, P-interaction <0.001 and <0.05). In conclusion, a diet low in GI and moderate in CHO content (i.e., low GL) may have health benefits by positively affecting daylong glycemia, IS, and liver fat.

Increased lipid synthesis and decreased β-oxidation in the liver of SHR/NDmcr-cp (cp/cp) rats, an animal model of metabolic syndrome

SHR/NDmcr-cp (cp/cp) rats (SHR/NDcp) are an animal model of metabolic syndrome. A previous study of ours revealed drastic increases in the mass of palmitic (16:0), oleic (18:1n-9), palmitoleic (16:1n-7), cis-vaccenic (18:1n-7) and 5,8,11-eicosatrienoic acids in the liver of SHR/NDcp. However, detailed information on the class of lipid accumulated and the mechanism responsible for the overproduction of the accumulated lipid in the liver was not obtained. This study aimed to characterize the class of lipid accumulated and to explore the mechanism underlying the lipid accumulation in the liver of SHR/NDcp, in comparison with SHR/NDmcr-cp (+/+) (lean hypertensive littermates of SHR/NDcp) and Wistar Kyoto rats. In the liver of SHR/NDcp, de novo synthesis of fatty acids (16:0, 18:1n-9 and 16:1n-7) and triacylglycerol (TAG) synthesis were up-regulated and fatty acid β-oxidation was down-regulated. These perturbations of lipid metabolism caused fat accumulation in hepatocytes and accumulation of TAG, which were enriched with 16:0, 18:1n-9 and 16:1n-7, in the liver of SHR/NDcp. On the other hand, no changes were found in hepatic contents of diacylglycerol and unesterified fatty acid (FFA); among FFA, there were no differences in the hepatic concentrations of unesterified 16:0 and stearic acid between SHR/NDcp and two other groups of rats. Moreover, little change was brought about in the expression of genes responsive to endoplasmic reticulum stress in the liver of SHR/NDcp. These results may reinforce the pathophysiological role of stearoyl-CoA desaturase 1 and fatty acid elongase 6 in the liver of SHR/NDcp.