Visceral fat: a key mediator of steatohepatitis in metabolic liver disease

Nonalcoholic fatty liver disease and the coronary artery disease

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is increasingly prevalent and is recognized as part of the metabolic syndrome (MetS). Patients with NAFLD have a lower life expectancy compared to the general population, with coronary artery disease (CAD) as the leading cause of death.

AIMS

We aim to address the epidemiological data of CAD, the possible pathogenesis or linkage mechanisms of NAFLD and atherosclerosis and the strategies to reduce the CAD risk in NAFLD patients.

METHODS

We reviewed data from a Medline and PubMed search which was performed to identify relevant literature using search terms "NAFLD," "metabolic syndrome" and "coronary artery disease."

RESULTS

Patients with steatohepatitis, a part of the spectrum of NAFLD, have more cardiovascular events than patients without steatohepatitis. However, the association between liver histological progression and the risk of CAD events is not linear. A multidisciplinary approach to NAFLD patients based on controlling related risk factors and monitoring for CAD risks and liver complications is necessary. The combination of lifestyle modification with pharmacological treatment tailored to each individual's risk factors needs to be considered. There is a need for more research on primary prevention for CAD in NAFLD patients and interventional studies for determining the nature of the relationship between NAFLD and CAD.

CONCLUSIONS

NAFLD is recognized as part of the MetS and increases cardiovascular risks. Therefore, a multidisciplinary approach to these patients of controlling the related risk factors and monitoring for cardiovascular and liver complications must be done.

The development of chronic kidney disease in Japanese patients with non-alcoholic fatty liver disease

Objective Chronic kidney disease (CKD) is present in patients with nonalcoholic fatty liver disease (NAFLD). The aim of this retrospective study was to assess the cumulative development incidence and predictive factors for new onset of CKD in Japanese patients with NAFLD. Methods A total of 5,561 NAFLD patients without CKD were enrolled. CKD was defined as either an estimated glomerular filtration rate of <60 mL/min/1.73 m(2) or dipstick proteinuria (≥+1). A blood sample and a urine sample were taken for routine analyses during follow-up. The mean observation period was 5.5 years. The primary goal is the new development of CKD. Independent factors associated with new development of CKD were analyzed by using the Kaplan-Meyer method and the Cox proportional hazards model. Results Of 5.561 NAFLD patients, 263 patients developed CKD. The cumulative development rate of CKD was 3.1% at the 5th year and 12.2% at the 10th year. Multivariate Cox proportional hazards analysis showed that CKD development in patients with NAFLD occurred when patient had low level of GFR of 60-75 mL/min/1.73 m(2) [hazard ratio:2.75; 95% confidence interval (CI)=1.93-3.94; p<0.001], age of ≥50 years (hazard ratio: 2.67; 95% CI=2.06-3.46; p<0.001), diabetes (hazard ratio: 1.92; 95% CI=1.45-2.54; p<0.001), hypertension (hazard ratio: 1.69; 95% CI=1.25-2.29; p<0.001), and elevated serum gamma-glutamyltransferase of ≥109 IU/L (hazard ratio: 1.35; 95% CI=1.02-1.78; p=0.038). Conclusion Our retrospective study indicates that the annual incidence of CKD in Japanese patients with NAFLD is about 1.2%. Five factors of low eGFR level, aging, type 2 diabetes, hypertension, and elevated gamma-glutamyltransferase, increases the risk of the development of CKD.

Inflammatory modulation of exercise salience: using hormesis to return to a healthy lifestyle

Most of the human population in the western world has access to unlimited calories and leads an increasingly sedentary lifestyle. The propensity to undertake voluntary exercise or indulge in spontaneous physical exercise, which might be termed "exercise salience", is drawing increased scientific attention. Despite its genetic aspects, this complex behaviour is clearly modulated by the environment and influenced by physiological states. Inflammation is often overlooked as one of these conditions even though it is known to induce a state of reduced mobility. Chronic subclinical inflammation is associated with the metabolic syndrome; a largely lifestyle-induced disease which can lead to decreased exercise salience. The result is a vicious cycle that increases oxidative stress and reduces metabolic flexibility and perpetuates the disease state. In contrast, hormetic stimuli can induce an anti-inflammatory phenotype, thereby enhancing exercise salience, leading to greater biological fitness and improved functional longevity. One general consequence of hormesis is upregulation of mitochondrial function and resistance to oxidative stress. Examples of hormetic factors include calorie restriction, extreme environmental temperatures, physical activity and polyphenols. The hormetic modulation of inflammation, and thus, exercise salience, may help to explain the highly heterogeneous expression of voluntary exercise behaviour and therefore body composition phenotypes of humans living in similar obesogenic environments.

Restriction of calorie and iron intake results in reduction of visceral fat and serum alanine aminotransferase and ferritin levels in patients with chronic liver disease

AIM

  To clarify the impact of visceral fat on chronic liver diseases such as non-alcoholic fatty liver disease (NAFLD) and hepatitis C, we investigated the effects of lifestyle modifications on the amount of visceral fat, liver biochemistry and serum ferritin levels in patients with liver disease.

METHODS

  Eighty-two patients (NAFLD, n = 37; hepatitis C, n = 45) were advised to adopt lifestyle modifications, including dietary changes and exercise, and these were maintained for 6 months. Bodyweight, percentage of body fat, visceral fat area (VFA) and serum alanine aminotransferase (ALT) and ferritin were measured before and after intervention.

RESULTS

  In NAFLD, the mean VFA of 134.5 cm(2) was significantly reduced to 125.3 cm(2) after 6 months (P < 0.001). ALT levels improved significantly between the values measured before and after intervention (P = 0.039). The VFA prior to intervention was 100 cm(2) in hepatitis C patients and it was reduced significantly after 6 months to 95.6 cm(2) (P < 0.001). ALT levels also improved significantly in the hepatitis C patients (P < 0.001). The serum ferritin levels also reduced in these patients. Improvements in serum ALT and ferritin levels correlated with the amount of visceral fat reduction in both groups (P = 0.046, P = 0.008, respectively).

CONCLUSION

  These findings demonstrate that restriction of calorie and iron intake results in reduction of visceral fat, liver enzymes and ferritin in patients with chronic liver disease. Visceral fat may be a central target for future interventions, not only in NAFLD but also in hepatitis C.

Visceral adiposity index is associated with histological findings and high viral load in patients with chronic hepatitis C due to genotype 1

Metabolic factors have been associated with liver damage in patients with genotype 1 chronic hepatitis C (G1 CHC). We tested visceral adiposity index (VAI), a new marker of adipose dysfunction in G1 CHC, patients to assess its association with host and viral factors and its link to both histological findings and sustained virological response (SVR). Two hundred thirty-six consecutive G1 CHC patients were evaluated by way of liver biopsy and anthropometric and metabolic measurements, including insulin resistance (IR), homeostasis model assessment (HOMA), and VAI using waist circumference, body mass index, triglycerides, and high-density lipoprotein cholesterol. All biopsies were scored by one pathologist for staging and grading and graded for steatosis, which was considered moderate to severe if ≥ 30%. Multiple linear regression analysis revealed that VAI score was independently associated with higher HOMA score (P = 0.009), log10 hepatitis C virus RNA levels (P = 0.01), necroinflammatory activity (P = 0.04), and steatosis (P = 0.04). Multiple logistic regression analysis revealed that IR (OR 3.879, 95% CI 1.727-8.713, P = 0.001), higher VAI score (OR 1.472, 95% CI 1.051-2.062, P = 0.02), and fibrosis (OR 2.255, 95% CI 1.349-3.768, P = 0.002) were linked to steatosis ≥ 30%. Logistic regression analysis revealed that older age (OR 1.030, 95% CI 1.002-1.059, P = 0.03), higher VAI score (OR 1.618, 95% CI 1.001-2.617, P = 0.04), and fibrosis (OR 2.608, 95% CI 1.565-4.345, P < 0.001) were independently associated with moderate to severe necroinflammatory activity. No independent associations were found between VAI score and both fibrosis and SVR.

CONCLUSION

In G1 CHC patients, higher VAI score is independently associated with both steatosis and necroinflammatory activity and has a direct correlation with viral load.

Evolution of inflammation in nonalcoholic fatty liver disease: the multiple parallel hits hypothesis

Whereas in most cases a fatty liver remains free of inflammation, 10%-20% of patients who have fatty liver develop inflammation and fibrosis (nonalcoholic steatohepatitis [NASH]). Inflammation may precede steatosis in certain instances. Therefore, NASH could reflect a disease where inflammation is followed by steatosis. In contrast, NASH subsequent to simple steatosis may be the consequence of a failure of antilipotoxic protection. In both situations, many parallel hits derived from the gut and/or the adipose tissue may promote liver inflammation. Endoplasmic reticulum stress and related signaling networks, (adipo)cytokines, and innate immunity are emerging as central pathways that regulate key features of NASH.

Fat: a matter of disturbance for the immune system

Obesity is increasingly being recognized as a risk factor for a number of benign and malignant gastrointestinal conditions. However, literature on the underlying pathophysiological mechanisms is sparse and ambiguous. There is compelling evidence that both overnutrition and undernutrition negatively interfere with the immune system. Overnutrition has been found to increase susceptibility to the development of inflammatory diseases, autoimmune diseases and cancer. In the regulation of immune and inflammatory processes, white adipose tissue plays a critical role, not only as an energy store but also as an important endocrine organ. The obese state is characterised by a low-grade systemic inflammation, mainly as a result of increased adipocytes as well as fat resident- and recruited-macrophage activity. In the past few years, various products of adipose tissue including adipokines and cytokines have been characterised and a number of pathways linking adipose tissue metabolism with the immune system have been identified. Activation of the innate immune system plays a major role in hepatic steatosis. Non-alcoholic fatty liver disease includes a wide spectrum of diseases, from pure steatosis to non-alcoholic steatohepatitis in the absence of significant alcohol consumption. Although steatosis is considered a non-progressive disease, non-alcoholic steatohepatitis may deteriorate in advanced chronic liver diseases, cirrhosis, and hepatocellular carcinoma. An important parallel between obesity-related pathology of adipose tissue and liver pertains to the emerging role of macrophages, and growing evidence suggests that Kupffer cells critically contribute to progression of non-alcoholic fatty liver disease. Moreover, a close link between specific immune activation and atherosclerosis has been well established, suggesting that fat can directly trigger immune responses. This review discusses the role of fat as "a matter of disturbance for the immune system" with a focus on hepatic steatosis.

Role and cellular source of nicotinamide adenine dinucleotide phosphate oxidase in hepatic fibrosis

Reactive oxygen species (ROS) generated by nicotinamide adenine dinucleotide phosphate oxidase (NOX) is required for liver fibrosis. This study investigates the role of NOX in ROS production and the differential contribution of NOX from bone marrow (BM)-derived and non-BM-derived liver cells. Hepatic fibrosis was induced by bile duct ligation (BDL) for 21 days or by methionine-choline-deficient (MCD) diet for 10 weeks in wild-type (WT) mice and mice deficient in p47phox (p47phox knockout [KO]), a component of NOX. The p47phox KO chimeric mice were generated by the combination of liposomal clodronate injection, irradiation, and BM transplantation of p47phox KO BM into WT recipients and vice versa. Upon BDL, chimeric mice with p47phox KO BM-derived cells, including Kupffer cells, and WT endogenous liver cells showed a ∼25% reduction of fibrosis, whereas chimeric mice with WT BM-derived cells and p47phox KO endogenous liver cells, including hepatic stellate cells, showed a ∼60% reduction of fibrosis. In addition, p47phox KO compared to WT mice treated with an MCD diet showed no significant changes in steatosis and hepatocellular injury, but a ∼50% reduction in fibrosis. Cultured WT and p47phox KO hepatocytes treated with free fatty acids had a similar increase in lipid accumulation. Free fatty acids promoted a 1.5-fold increase in ROS production both in p47phox KO and in WT hepatocytes.

CONCLUSION

NOX in both BM-derived and non-BM-derived cells contributes to liver fibrosis. NOX does not play a role in experimental steatosis and the generation of ROS in hepatocytes, but exerts a key role in fibrosis.

Nonalcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD), the most common liver disorder in the Western world, is a clinico-histopathological entity in which excessive triglyceride accumulation in the liver occurs. Non-alcoholic steatohepatitis (NASH) represents the necroinflammatory form, which can lead to advanced liver fibrosis, cirrhosis, and hepatocellular carcinoma. The pathogenesis of NAFLD/NASH is complex but increased visceral adiposity plus insulin resistance with increased free fatty acids release play an initial key role for the onset and perpetuation of liver steatosis. Further events in the liver include oxidative stress and lipid peroxidation, decreased antioxidant defences, early mitochondrial dysfunction, iron accumulation, unbalance of adipose-derived adipokines with a chronic proinflammatory status, and gut-derived microbial adducts. New gene polymorphisms increasing the risk of fatty liver, namely APOC3 and PNPLA3, have been lately identified allowing further insights into the pathogenesis of this condition. In our review pathophysiological, genetic, and essential diagnostic and therapeutic aspects of NAFLD are examined with future trends in this field highlighted.

Nonalcoholic steatohepatitis: risk factors and diagnosis

Nonalcoholic steatohepatitis (NASH) represents the progressive form of nonalcoholic fatty liver disease with greater potential to lead to liver-related morbidity and mortality. Diagnosing NASH mandates more intensive clinical management and consideration for clinical trials. Currently, the diagnosis of NASH requires a liver biopsy, which is invasive, with drawbacks in sampling and interpretation error. Clinical risk factors for NASH include diabetes and the metabolic syndrome; however, these are not sufficiently predictive of the condition by themselves. Routine liver aminotransaminase levels are not reliable; however, novel plasma hepatocyte apoptosis markers, either alone or in combination with clinical risk factors, are potential noninvasive diagnostic tools for the future.

Endocannabinoids, FOXO and the metabolic syndrome: redox, function and tipping point--the view from two systems

The endocannabinoid system (ECS) was only 'discovered' in the 1990s. Since then, many new ligands have been identified, as well as many new intracellular targets--ranging from the PPARs, to mitochondria, to lipid rafts. It was thought that blocking the CB-1 receptor might reverse obesity and the metabolic syndrome. This was based on the idea that the ECS was dysfunctional in these conditions. This has met with limited success. The reason may be that the ECS is a homeostatic system, which integrates energy seeking and storage behaviour with resistance to oxidative stress. It could be viewed as having thrifty actions. Thriftiness is an innate property of life, which is programmed to a set point by both environment and genetics, resulting in an epigenotype perfectly adapted to its environment. This thrifty set point can be modulated by hormetic stimuli, such as exercise, cold and plant micronutrients. We have proposed that the physiological and protective insulin resistance that underlies thriftiness encapsulates something called 'redox thriftiness', whereby insulin resistance is determined by the ability to resist oxidative stress. Modern man has removed most hormetic stimuli and replaced them with a calorific sedentary lifestyle, leading to increased risk of metabolic inflexibility. We suggest that there is a tipping point where lipotoxicity in adipose and hepatic cells induces mild inflammation, which switches thrifty insulin resistance to inflammation-driven insulin resistance. To understand this, we propose that the metabolic syndrome could be seen from the viewpoint of the ECS, the mitochondrion and the FOXO group of transcription factors. FOXO has many thrifty actions, including increasing insulin resistance and appetite, suppressing oxidative stress and shifting the organism towards using fatty acids. In concert with factors such as PGC-1, they also modify mitochondrial function and biogenesis. Hence, the ECS and FOXO may interact at many points; one of which may be via intracellular redox signalling. As cannabinoids have been shown to modulate reactive oxygen species production, it is possible that they can upregulate anti-oxidant defences. This suggests they may have an 'endohormetic' signalling function. The tipping point into the metabolic syndrome may be the result of a chronic lack of hormetic stimuli (in particular, physical activity), and thus, stimulus for PGC-1, with a resultant reduction in mitochondrial function and a reduced lipid capacitance. This, in the context of a positive calorie environment, will result in increased visceral adipose tissue volume, abnormal ectopic fat content and systemic inflammation. This would worsen the inflammatory-driven pathological insulin resistance and inability to deal with lipids. The resultant oxidative stress may therefore drive a compensatory anti-oxidative response epitomised by the ECS and FOXO. Thus, although blocking the ECS (e.g. via rimonabant) may induce temporary weight loss, it may compromise long-term stress resistance. Clues about how to modulate the system more safely are emerging from observations that some polyphenols, such as resveratrol and possibly, some phytocannabinoids, can modulate mitochondrial function and might improve resistance to a modern lifestyle.

Prevalence of ultrasound-diagnosed non-alcoholic fatty liver disease in a hospital cohort and its association with anthropometric, biochemical and sonographic characteristics

Non-alcoholic fatty liver disease (NAFLD) is considered as the most common liver disease in Western countries with still rising prevalence due to a lifestyle favoring the development of the metabolic syndrome.

AIM

To investigate the prevalence of ultrasound-diagnosed NAFLD in patients with referral for sonographic examination of the abdomen, and to determine risk factors.

METHODS

After exclusion of patients with known liver disease or risk factors for secondary NAFLD, a total of 155 arbitrarily selected patients (mean age 53.6±17.4 years; 52.6% male) from the interdisciplinary ultrasound department of a German University Hospital were included in this prospective study. Each patient underwent a standardized ultrasound, anthropometric and biochemical examination.

RESULTS

The prevalence of ultrasound-diagnosed NAFLD was 40.0%. NAFLD-patients had significantly higher body mass index (BMI) and waist-to-hip ratio, higher rates of reported hypertension and diabetes mellitus, and lower HDL cholesterol serum levels. Furthermore, NAFLD-patients revealed significantly higher serum ALT levels (23.2±22.1 U/l vs. 15.0±8.2 U/l; p=0.001), lower AST/ALT ratio (1.76±0.79 vs. 2.11±0.94; p=0.019), and notably, decreased flow in the portal vein (22.9±6.3 cm/s vs. 26.7±10.5 cm/s; p=0.011). Multivariate analysis revealed BMI (odds ratio (OR): 14.05; 95% Confidence interval (CI): 3.3-59.8), AST/ALT ratio (OR: 0.39; CI: 0.18-0.82), and HDL-C (OR: 4.33; CI: 1.6-11.9) as independent risk factors.

CONCLUSIONS

Ultrasound-diagnosed NAFLD is frequent in patients with referral for ultrasound examination of the abdomen, and our findings further support that NAFLD is the hepatic manifestation of the metabolic syndrome with obesity being the most important risk factor.

Different levels of overnutrition and weight gain during pregnancy have differential effects on fetal growth and organ development

BACKGROUND

Nearly 50% of U.S. women of child-bearing age are overweight or obese, conditions linked to offspring obesity and diabetes.

METHODS

Utilizing the sheep, females were fed a highly palatable diet at two levels of overfeeding designed to induce different levels of maternal body weight increase and adiposity at conception, and from conception to midgestation. Fetal growth and organ development were then evaluated at midgestation in response to these two different levels of overfeeding. Ewes were fed to achieve: 1) normal weight gain (control, C), 2) overweight (125% of National Research Council [NRC] recommendations, OW125) or 3) obesity (150% of NRC recommendations, OB150) beginning 10 wks prior to breeding and through midgestation. Body fat % and insulin sensitivity were assessed at three points during the study: 1) diet initiation, 2) conception and 3) mid-gestation. Ewes were necropsied and fetuses recovered at mid-gestation (day 78).

RESULTS

OB150 ewes had a higher % body fat than OW125 ewes prior to breeding (P = 0.03), but not at mid-gestation (P = 0.37). Insulin sensitivity decreased from diet initiation to mid-gestation (P = 0.04), and acute insulin response to glucose tended to be greater in OB150 ewes than C ewes (P = 0.09) and was greater than in OW125 ewes (P = 0.02). Fetal crown-rump length, thoracic and abdominal girths, and fetal perirenal fat were increased in the OW125 and OB150 versus C ewes at mid-gestation. However, only fetal heart, pancreas, and liver weights, as well as lipid content of fetal liver, were increased (P < 0.05) in OB150 ewes versus both C and OW125 ewes at midgestation.

CONCLUSIONS

These data demonstrate that different levels of overfeeding, resulting in differing levels of maternal weight gain and adiposity prior to and during pregnancy, lead to differential effects on fetal overgrowth and organ development.

Visceral adipose tissue and inflammation correlate with elevated liver tests in a cohort of overweight and obese patients

OBJECTIVE

To study the relationship between elevated liver tests and high sensitive C-reactive protein (hs-CRP), as potential markers of liver inflammation and non-alcoholic steatohepatitis (NASH), with anthropometric and laboratory parameters in overweight patients, especially the relationship with visceral adipose tissue (VAT).

METHODS

Patients presenting to the obesity clinic were prospectively included. Detailed anthropometry, computed tomography (CT)-measured VAT, liver tests (aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP) and gamma-glutamyl transferase (GGT)) and hs-CRP were assessed, along with an extended series of biochemical parameters.

RESULTS

All 480 patients (gender distribution male (M)/female (F) (10/90%)) with complete data were included. Mean age was 39+/-13 years, mean BMI 34.5+/-6.0 kg m(-2). In 37.3% of the patients one or more of the liver tests were elevated. VAT was positively related to AST (r=0.18, P<0.001), ALT (r=0.29, P<0.001), ALP (r=0.16, P<0.01) and GGT (r=0.39, P<0.001). Comparing subjects with high (VAT>or=113 cm(2)) vs low (VAT<113 cm(2)) VAT levels, significant differences were noted for AST (26+/-12 vs 24+/-12 U l(-1), P=0.003), ALT (37+/-21 vs 31+/-21 U l(-1), P<0.001), ALP (76+/-20 vs 71+/-18 U l(-1), P=0.008), GGT (33+/-20 vs 25+/-15 U l(-1), P<0.001) and hs-CRP (0.62+/-0.43 vs 0.52+/-0.48 mg dl(-1), P<0.001). After correction for BMI the difference in AST and ALP between the high vs low VAT group disappeared. The differences for ALT and GGT remained significant (P=0.008 and P<0.001 respectively). After correction for hs-CRP the four different liver tests remained significantly higher in the high VAT group. A stepwise multiple regression analysis revealed that every single liver test has his own most important determinant; VAT and hs-CRP for AST, insulin resistance calculated with homeostasis model assessment (HOMA-IR) and hs-CRP for ALT and ALP, and triglycerides and VAT for GGT.

CONCLUSION

In overweight and obese patients, liver tests, especially ALT and GGT, are associated with visceral fat mass. After correction for BMI and hs-CRP, ALT and GGT are significantly higher in patients with increased VAT, thereby supporting evidence for a potential key role of VAT in the pathogenesis of non-alcoholic fatty liver disease (NAFLD).

Protective roles of adiponectin in obesity-related fatty liver diseases: mechanisms and therapeutic implications

Adiponectin is an insulin-sensitizing adipokine possessing multiple beneficial effects on obesity-related medical complications. This adipokine is secreted from adipocytes into the circulation as three oligomeric isoforms, including trimer, hexamer and the high molecular weight (HMW) oligomeric complex. Each oligomeric isoform of adiponectin possesses distinct biological properties and activates different signaling pathways in various target tissues. The hepato-protective activities have been demonstrated by many clinical and experimental studies. The decreased level of serum adiponectin represents an independent risk factor for nonalcoholic fatty liver disease (NAFLD) and liver dysfunctions in humans. In animals, elevation of circulating adiponectin by either pharmacological or genetic approaches leads to a significant alleviation of hepatomegaly, steatosis and necro-inflammation associated with various liver diseases. In adiponectin knockout mice, there is a pre-existing condition of hepatic steatosis and mitochondria dysfunction, which might contribute to the increased vulnerabilities of these mice to the secondary liver injuries induced by obesity and other conditions. This review aims to summarize recent advances on delineation of the structural, molecular and cellular mechanisms underlying the hepato-protective properties of adiponectin.

Nonalcoholic fatty liver disease: pathology and pathogenesis

Nonalcoholic fatty liver disease (NAFLD) is recognized as the leading cause of chronic liver disease in adults and children. NAFLD encompasses a spectrum of liver injuries ranging from steatosis to steatohepatitis with or without fibrosis. Fibrosis may progress to cirrhosis and complications including hepatocellular carcinoma. Histologic findings represent the complexity of pathophysiology. NAFLD is closely associated with obesity and is most closely linked with insulin resistance; the current Western diet, high in saturated fats and fructose, plays a significant role. There are several mechanisms by which excess triglycerides are acquired and accumulate in hepatocytes. Formation of steatotic droplets may be disordered in NAFLD. Visceral adipose tissue dysfunction in obesity and insulin resistance results in aberrant cytokine expression; many cytokines have a role in liver injury in NAFLD. Cellular stress and immune reactions, as well as the endocannabinoid system, have been implicated in animal models and in some human studies.

Relationship of non-alcoholic fatty liver disease to colorectal adenomatous polyps

BACKGROUND AND AIMS

Metabolic syndrome and insulin resistance are associated with a higher risk of colon cancer. Non-alcoholic fatty liver disease (NAFLD) is regarded as a manifestation of metabolic syndrome in the liver. This investigation was initiated to determine whether NAFLD has a relationship to colorectal adenomatous polyps.

METHODS

We examined the 2917 participants who underwent a routine colonoscopy at Kangbuk Samsung Hospital in 2007. We divided the 2917 subjects into the adenomatous polyp group (n = 556) and the normal group (n = 2361). Anthropometric measurements, biochemical tests for liver and metabolic function, and abdominal ultrasonographs were assessed.

RESULTS

The prevalence of NAFLD was 41.5% in the adenomatous polyp group and 30.2% in the control group. By multiple logistic regression analysis, NAFLD was found to be associated with an increased risk of colorectal adenomatous polyps (odds ratio, 1.28; 95% confidence interval, 1.03-1.60). An increased risk for NAFLD was more evident in patients with a greater number of adenomatous polyps.

CONCLUSION

NAFLD was associated with colorectal adenomatous polyps. Further studies are needed to confirm whether NAFLD is a predictor for the development of colorectal adenomatous polyps and cancer.

Long-term effects of metformin and lifestyle modification on nonalcoholic Fatty liver disease obese adolescents

Objective. To assess the long-term effects of metformin in combination with lifestyle intervention and its association between insulin levels and the degree of steatosis at ultrasonography (US) in obese adolescents. Methods. Thirty-five postpubertal obese boys were randomized into two groups: one receiving metformin in combination with a multidisciplinary lifestyle intervention versus a placebo group, which also received the same intervention. The visceral, subcutaneous fat and degree of steatosis were measured by ultrasonography. Fasting blood samples were collected to analyze glucose, insulin, insulin resistance, and aminotransferases. Repeated ANOVA measures were used to compare changes over time and between groups, and Spearman's correlations were used to identify an association between insulin and the degree of steatosis at US. Results. There was a positive correlation between the degree of steatosis at US with insulin concentrations and HOMA-IR. Long-term therapy plus metformin significantly reduced body weight, body mass index, insulin, HOMA-IR, and visceral fat. Conclusions. Metformin was more effective than the placebo in improving clinical parameters associated with obesity and steatosis.

Visceral adiposity is not associated with inflammatory markers in trauma patients

BACKGROUND

Excess visceral adiposity induces chronic subclinical inflammation resulting in the metabolic syndrome. Whether excess visceral adiposity impacts posttraumatic inflammatory profiles more is unknown. We hypothesized that obese patients (body mass index >30 kg/m) with higher visceral to subcutaneous adipose tissue distribution would have increased inflammatory outcomes.

METHODS

A secondary analysis of a prospective cohort of adult trauma patients requiring >48 hours of intensive care unit care over a 55-month period was analyzed. Body fat distribution was determined by radiologist review of computed tomography scans at L1. Concentric freeform regions were defined manually, and area was calculated. Visceral adiposity was defined as subcutaneous fat area: visceral area >1.35 (the median), whereas subcutaneous adiposity was defined as a ratio <1.35. Primary outcomes were proinflammatory biomarkers known to be associated with chronic visceral obesity (white blood cell count, interleukin 1, 2, 4, 6, 8, 10, and tumor necrosis factor alpha). Secondary outcomes were all-cause in-hospital mortality, adult respiratory distress syndrome, and nosocomial infections.

RESULTS

Two hundred eighty-one (19%) obese patients with available computed tomography scans from 1,510 trauma patients were included. Visceral adiposity included 140 patients, subcutaneous adiposity included 141 patients. The two groups were similar in regards to age, Trauma Injury Severity Score, and Acute Physiology and Chronic Health Evaluation II score. There was no difference (p > 0.05) in proinflammatory biomarkers. Patients with visceral adiposity had similar clinical outcomes including mortality (p = 0.56), adult respiratory distress syndrome (p = 0.69), and infection (0.43).

CONCLUSIONS

Visceral body fat distribution in obese patients is not associated with increased inflammatory profiles or clinical outcomes after trauma. The impact of injury severity on acute inflammation likely overwhelms the metabolic disturbances and subclinical inflammation associated with visceral obesity in the chronic setting.

Advances in understanding the role of leptin, adiponectin and resistin in liver fibrogenesis

Liver fibrosis is a wound healing reaction in response to a variety of chronic liver insults and is characterized by excessive extracellular matrix deposition within the liver. The term "adipocytokines]represents a group of polypeptide molecules produced primarily by adipose tissue. Accumulating evidence demonstrates that adipocytokines play a pivotal role in the pathogenesis of chronic liver diseases, such as nonalcoholic fatty liver disease. In this article, we will summarize the recent findings concerning the role of adipocytokines, such as leptin, adiponectin and resistin, in liver fibrogenesis.

Kupffer cell activation is a causal factor for hepatic insulin resistance

Recruited adipose tissue macrophages contribute to chronic and low-grade inflammation causing insulin resistance in obesity. Similarly, we hypothesized here that Kupffer cells, the hepatic resident macrophages, play a pathogenic role in hepatic insulin resistance induced by a high-fat diet. Mice were fed a normal diet or high-fat diet for 3 days. Kupffer cell activation was evaluated by immunohistochemistry and quantitative RT-PCR. Insulin sensitivity was assessed in vivo by hyperinsulinemic-euglycemic clamp and insulin-activated signaling was investigated by Western blot. Liposome-encapsulated clodronate was injected intravenously to deplete macrophages prior to a short-term exposure to high-fat diet. Here, we characterized a short-term high-fat diet model in mice and demonstrated early hepatic insulin resistance and steatosis concurrent with Kupffer cell activation. We demonstrated that selective Kupffer cell depletion obtained by intravenous clodronate, without affecting adipose tissue macrophages, was sufficient to enhance insulin-dependent insulin signaling and significantly improve hepatic insulin sensitivity in vivo in this short-term high-fat diet model. Our study clearly shows that hepatic macrophage response participates to the onset of high-fat diet-induced hepatic insulin resistance and may therefore represent an attractive target for prevention and treatment of diet- and obesity-induced insulin resistance.

Effect of 6-month nutritional intervention on non-alcoholic fatty liver disease

OBJECTIVE

We evaluated the effect of diet therapy as exclusive treatment on insulin resistance, biochemical parameters of metabolic syndrome, and degree of hepatic steatosis in patients with non-alcoholic fatty liver disease.

METHODS

Thirty-one patients with non-alcoholic fatty liver disease received a diet with a reduction of 500 to 1000 cal/d, containing 15% protein, 55% carbohydrates, and 30% fat, for 6 mo. At entry and 6 mo after dietary instructions, degrees of hepatic steatosis and visceral obesity were assessed by computed tomography; serum aspartate aminotransferase, alanine aminotransferase, γ-glutamyl transferase, glucose, triacylglycerols, and high-density lipoprotein cholesterol were measured by automated methods. Body mass index, waist circumference, waist-to-hip ratio, and food intake (7-d diary) were also evaluated. At the end of follow-up, the patients were classified as adherent or non-adherent to treatment according to a weight loss of more or less than 5% of initial body weight, respectively.

RESULTS

Seventeen patients were classified as adherent (group 1) and 14 as non-adherent (group 2). Group 2 only presented a significant reduction in body mass index and waist circumference. In contrast, in group 1, in addition to significant improvement of all anthropometric parameters, a significant reduction was observed in alanine aminotransferase and γ-glutamyl transferase levels, homeostasis model assessment for insulin resistance, visceral fat and tomographic liver density, together with an increase in serum high-density lipoprotein cholesterol levels. These patients presented a significant decrease in total energy intake and in total and saturated fats.

CONCLUSION

Nutritional intervention as exclusive treatment, with a loss of at least 5% of initial weight, is effective in the treatment of non-alcoholic fatty liver disease.

Association of serum leptin levels with homeostasis model assessment-estimated insulin resistance and metabolic syndrome: the key role of central obesity

BACKGROUND

Leptin is correlated with several features of metabolic syndrome; however, possible confounders (eg, obesity) of this association are not known. This study evaluated the relationship between leptin, metabolic syndrome, and insulin resistance in an Iranian population and further investigated whether this relationship is confounded by obesity or central obesity.

METHODS

A total of 387 participants (18-65 years old) who referred to a large university general hospital for routine health examinations were categorized into 2 groups with (n = 130) and without (n = 257) metabolic syndrome. Fasting plasma glucose, insulin, lipids, and leptin levels were measured and the homeostasis model assessment of insulin resistance (HOMA-IR) was calculated. Metabolic syndrome was defined according to the National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) criteria.

RESULTS

Age- and sex-adjusted leptin levels were significantly higher in patients with than those without metabolic syndrome (29.62 +/- 1.67 vs. 18.50 +/- 1.21 ng/mL, P < 0.001). After adjustment for age, sex, and body mass index (BMI), leptin values were significantly correlated with HOMA-IR (P < 0.001), metabolic syndrome, and its components (P < 0.05). After adjustment for waist circumference, however, these associations were no longer statistically significant.

CONCLUSIONS

We demonstrated that high leptin levels are associated with insulin resistance and metabolic syndrome independent of BMI but these associations are significantly mediated through the effects of central obesity.

Multivariate analysis of risk factors for the development of type 2 diabetes in nonalcoholic fatty liver disease

PURPOSE

Diabetes is present in patients with nonalcoholic fatty liver disease (NAFLD). The aim of this retrospective cohort study was to assess the cumulative development of type 2 diabetes and predictive factors for its development in Japanese patients with NAFLD.

METHODS

A total of 6003 NAFLD patients diagnosed by ultrasonography were enrolled. The mean follow-up period was 4.9 years. An overnight (12 h) fasting blood sample or a casual blood sample was taken for routine analyses during follow up. The primary outcome was the development of type 2 diabetes. Evaluation was performed by using the Kaplan-Meier method and Cox proportional hazards analysis.

RESULTS

Of the 6003 NAFLD patients, 411 patients developed type 2 diabetes. The cumulative development rate of type 2 diabetes was 6.8% at the 5th year and 17.7% at the 10th year. Multivariate Cox proportional hazards analysis showed that type 2 diabetes development in patients with NAFLD occurred when patients had prediabetes status (hazard ratio 6.39; 95% confidence interval 5.00-8.18; P < 0.001), mean serum gamma-glutamyltransferase (GGT) level of more than 109 IU/l (hazard ratio 1.60; 95% confidence interval 1.22-2. 02; P < 0.001), mean serum triglyceride (TG) level of more than 150 mg/l (hazard ratio 1.28; 95% confidence interval 1.05-1.55; P = 0.020), and physical activity of less than 60 min per week (hazard ratio 1.60; 95% confidence interval 1.25-2.00; P < 0.001).

CONCLUSIONS

The improvement of prediabetes status and physical activity, and the normalization of mean GGT and TG levels during follow up are important to prevent the development of T2DM in patients with NAFLD.

Metabolic syndrome and hepatocellular carcinoma: two growing epidemics with a potential link

Hepatocellular carcinoma (HCC) is the most rapidly increasing cause of cancer death in the United States. Although many risk factors for HCC are well defined, including hepatitis B virus (HBV), hepatitis C virus (HCV), and alcohol, most series have indicated that 5% to 30% of patients with HCC lack a readily identifiable risk factor for their cancer. The majority of "cryptogenic" HCC in the United States is attributed to nonalcoholic fatty liver disease (NAFLD), a hepatic manifestation of the metabolic syndrome. The metabolic syndrome is a constellation of problems that includes insulin resistance, obesity, hypertension, and hyperlipidemia. Increasingly, components of the metabolic syndrome are being linked to various forms of cancer with respect to both increased risk of disease and worsened outcome. In this review, the authors focused on the relation between metabolic syndrome and HCC. They investigated the increased risks of HCC among individuals with features of metabolic syndrome, potentially worsened cancer outcomes in these patients, possible pathogenic mechanisms to explain these relations, and treatment options for those with NAFLD and its progressive counterpart, nonalcoholic steatohepatitis. It is predicted that metabolic syndrome will lead to large increases in the incidence of HCC over the next decades. A better understanding of the relation between these 2 diseases ultimately should lead to improved screening and treatment options for patients with HCC.

Immature myeloid cells induced by a high-fat diet contribute to liver inflammation

Chronic inflammation plays a critical role in promoting obesity-related disorders, such as fatty liver disease. The inflammatory cells that mediate these effects remain unknown. This study investigated the accumulation of immature myeloid cells in the liver and their role in liver inflammation. We found that the accumulation of immature myeloid cells, i.e., CD11b(+)Ly6C(hi)Ly6G(-) cells, in the liver of B6 mice fed a high-fat diet contribute to liver inflammation. Adoptive transfer of CD11b(+)Ly6C(hi)Ly6G(-) cells isolated from the liver of obese B6 mice, but not from lean B6 mice, resulted in liver damage that was evident by an increase in the activity of liver transferases in serum. CD11b(+)Ly6C(hi)Ly6G(-) cells isolated from the liver of obese mice are more easily activated by way of Toll-like receptor (TLR) stimulation resulting in interleukin 12 and other inflammatory cytokine expression in an MyD88-dependent fashion. TLR7-activated CD11b(+)Ly6C(hi)Ly6G(-) cells also enhance liver natural killer T cell (NKT) death in an Fas-dependent manner. Experiments using mice depleted of Gr-1(+) immature myeloid cells demonstrated the important role of CD11b(+)Ly6C(hi)Ly6G(-) in liver inflammation. Repeated injection of exosome-like particles causes CD11b(+) cell activation and subsequent homing to and accumulation of the cells in the liver.

CONCLUSION

Consumption of a high-fat diet by B6 mice triggers an accumulation of immature myeloid cells in the liver. The immature myeloid cells release proinflammatory cytokines and induce NKT cell apoptosis. Activation-induced NKT apoptosis further promotes excessive production of Th-1 cytokines. This diet-induced accumulation of immature myeloid cells may contribute to obesity-related liver disease.

Fatty liver and lipotoxicity

Fatty liver disease comprises a spectrum ranging from simple steatosis to steatohepatitis which can progress to liver cirrhosis and hepatocellular cancer. Hepatic lipotoxicity may ensue when the hepatic capacity to utilize, store and export fatty acids (FA) as triglycerides is overwhelmed. Additional mechanisms of hepatic lipotoxicity include abnormal FA oxidation with formation of reactive oxygen species, disturbances in cellular membrane FA and phospholipid composition, alterations of cholesterol content and ceramide signalling. Lipotoxicity is a key factor for the progression of fatty liver disease by inducing hepatocellular death, activating Kupffer cells and an inflammatory response, impairing hepatic insulin signalling resulting in insulin resistance, and activation of a fibrogenic response in hepatic stellate cells that can ultimately lead to cirrhosis. Therefore, the concept of hepatic lipotoxicity should be considered in future therapeutic concepts for fatty liver disease.

The liver and the waistline: Fifty years of growth

Fifty years of the Gastroenterological Society of Australia have witnessed the changing appearance of Australians. Asian immigration has transformed the dominant urban culture from European to Eurasian, with some unique Australian attributes. Meanwhile, global conditions have altered body shape, and our sports-proud country is now fat! Thus, as in North America, Europe, China, and affluent Asia-Pacific countries, prosperity and lifestyle, cheap processed foods coupled with reduced physical activity have created an epidemic of over-nutrition resulting in overweight/obesity. Additional genetic factors are at the core of the apple shape (central obesity) that typifies over-nourished persons with metabolic syndrome. Indigenous Australians, once the leanest and fittest humans, now have exceedingly high rates of obesity and type 2 diabetes, contributing to shorter life expectancy; Asian Australians are also at higher risk. Like non-steroidal anti-inflammatory drugs (NSAIDs) and cigarette smoking, obesity now contributes much to gastrointestinal morbidity and mortality (gastroesophageal reflux disease, cancers, gallstones, endoscopy complications). This review focuses on Australian research about fatty liver, particularly roles of central obesity/insulin resistance in non-alcoholic fatty liver disease/steatohepatitis (NAFLD/NASH). The outputs include many highly cited original articles and reviews and the first book on NAFLD. Studies have identified community prevalence, clinical outcomes, association with insulin resistance, metabolic syndrome and hypoadiponectinemia, developed and explored animal models for mechanisms of inflammation and fibrosis, conceptualized etiopathogenesis, and demonstrated that NASH can be reversed by lowering body weight and increasing physical activity. The findings have led to development of regional guidelines on NAFLD, the first internationally, and should now inform daily practice of gastroenterologists.

Subcutaneous rather than visceral adipose tissue is associated with adiponectin levels and insulin resistance in young men

INTRODUCTION

Studies on the association between adiponectin, body composition, and insulin resistance (IR) have been conflicting.

AIM

Our aim was to evaluate the impact of body composition on adiponectin and IR determined by homeostasis model assessment (HOMA) in a population-based study on relatively healthy young men, minimizing the possible effects of age, obesity, and severe comorbidity. DESIGN, METHODS, AND SUBJECTS: A population-based, cross-sectional study of 783 men aged 20-29 yr, randomly drawn from the Danish Central Personal Registry. Adiponectin was assessed using an in-house assay, and IR was determined using HOMA. Central fat mass (CFM) and lower extremity fat mass (LEFM) was measured by dual-energy x-ray absorptiometry, and visceral adipose tissue (VAT), sc adipose tissue (SAT), and thigh fat area (TFA) were assessed by magnetic resonance imaging.

RESULTS

Using multiple linear regression analysis, adiponectin correlated negatively with CFM (r = -0.27; P < 0.001) and SAT (r = -0.20; P < 0.001) and positively with LEFM (r = 0.19; P < 0.001) and TFA (r = 0.18; P < 0.001), whereas VAT did not associate significantly. In multiple linear regression analysis, HOMA-IR (dependent variable), correlated significantly with CFM (r = 0.27; P < 0.001) and SAT (r = 0.15; P < 0.001), whereas LEFM, VAT, or TFA did not correlate. Adiponectin was an independent predictor of HOMA-IR in both analyses (r = -0.14; P < 0.001).

CONCLUSION

SAT rather than VAT was inversely associated with adiponectin levels, and, interestingly, fat on the lower extremities was positively associated with adiponectin. Focusing on insulin resistance, SAT rather than VAT and TFA independently predicted a higher HOMA-IR. The observation that adiponectin was independently associated with lower HOMA-IR must be repeated in other populations.

Role of adipose tissue in haemostasis, coagulation and fibrinolysis

Obesity is associated with an increased incidence of insulin resistance (IR), type 2 diabetes mellitus and cardiovascular diseases. The increased risk for cardiovascular diseases could partly be caused by a prothrombotic state that exists because of abdominal obesity. Adipose tissue induces thrombocyte activation by the production of adipose tissue-derived hormones, often called adipokines, of which some such as leptin and adiponectin have been shown to directly interfere with platelet function. Increased adipose tissue mass induces IR and systemic low-grade inflammation, also affecting platelet function. It has been demonstrated that adipose tissue directly impairs fibrinolysis by the production of plasminogen activator inhibitor-1 and possibly thrombin-activatable fibrinolysis inhibitor. Adipose tissue may contribute to enhanced coagulation by direct tissue factor production, but hypercoagulability is likely to be primarily caused by affecting hepatic synthesis of the coagulation factors fibrinogen, factor VII, factor VIII and tissue factor, by releasing free fatty acids and pro-inflammatory cytokines (tumour necrosis factor-alpha, interleukin-1beta and interleukin-6) into the portal circulation and by inducing hepatic IR. Adipose tissue dysfunction could thus play a causal role in the prothrombotic state observed in obesity, by directly and indirectly affecting haemostasis, coagulation and fibrinolysis.

Non-alcoholic fatty liver disease pathogenesis: the present and the future

Non-alcoholic fatty liver disease is the clinical hepatic expression of metabolic syndrome. The prevalence of non-alcoholic fatty liver disease is around 20-30%, and with a rapid increase in the metabolic risk factors in the general population, non-alcoholic fatty liver disease has become the most common cause of liver disease worldwide. A fraction (20-30%) of non-alcoholic fatty liver disease patients develop a potentially progressive hepatic disorder, namely non-alcoholic steatohepatitis, leading to end-stage liver disease. The pathogenesis of non-alcoholic fatty liver disease is not entirely understood, and even if insulin resistance is a major pathogenetic key, many other factors are implicated in both liver fat accumulation and disease progression to non-alcoholic steatohepatitis. In this review we aim to examine the literature, principally concerning human non-alcoholic fatty liver disease pathogenesis, and to identify the newest, most promising clinical and basic research data.

Association between omental adipose tissue macrophages and liver histopathology in morbid obesity: influence of glycemic status

BACKGROUND/AIMS

Recently we showed that macrophage accumulation in omental adipose tissue is associated with liver fibro-inflammation in morbidly obese subjects. Here, we evaluated the influence of glycemic status and extended the analysis to the spectrum of obesity-linked liver damage.

METHODS

Liver biopsies, subcutaneous and omental adipose tissue were collected in 132 obese subjects during gastric bypass surgery. HAM56+ adipose tissue macrophages were counted in subjects classified by liver histopathology and by their degree of insulin resistance.

RESULTS

In the whole population, the number of omental macrophages increased with the score of steatosis, the non-alcoholic fatty liver disease activity score, the stage of fibrosis and with fibro-inflammation index. None of these relationships were significant with subcutaneous macrophage count. In insulin-sensitive participants, omental macrophages accumulation was higher in subjects with high indexes of fibro-inflammation (p=0.012 vs. low indexes). In insulin-resistant including type 2 diabetic participants, omental macrophage count was higher both in subjects with high scores of steatosis and in subjects with high indexes of fibro-inflammation (p<0.05 vs. low scores).

CONCLUSIONS

Macrophage accumulation in omental adipose tissue is associated with aggravated steatosis and fibro-inflammation in insulin-resistant obese subjects independently of altered glycemic status.

The metabolic syndrome and nonalcoholic fatty liver disease in children

PURPOSE OF REVIEW

Nonalcoholic fatty liver disease (NAFLD) is increasingly prevalent in pediatric-age individuals, in parallel with increasing obesity, and can lead to liver inflammation, fibrosis, and even cirrhosis. NAFLD appears tightly linked with features of the metabolic syndrome (MetS). This review aims to reconsider the clinical presentation, laboratory and pathologic assessment, and treatment of NAFLD, with a focus on its relationship with the MetS.

RECENT FINDINGS

NAFLD occurs with a high prevalence and severity in obese, insulin-resistant adolescents, especially Hispanic males. Pediatric NAFLD may improve with lifestyle therapy and agents that improve insulin sensitivity. In youth, NAFLD appears tightly correlated with components of the MetS, especially visceral fat, which appears to predict fibrosis as well as liver fat. In addition, noninvasive techniques such as transient elastography may help provide data on fibrosis in youth with NAFLD and avoid biopsy.

SUMMARY

The close association between NAFLD and the MetS supports screening for other comorbidities associated with the MetS. Further research is urgently required to best identify effective therapies to prevent and treat NAFLD, but its close association with MetS argues for a focus on strategies designed to improve insulin resistance and components of the MetS.

Visceral obesity and the risk of Barrett's esophagus in Japanese patients with non-alcoholic fatty liver disease

Background

The association between obesity and the risk of Barrett's esophagus (BE) is unclear. Furthermore, the association between visceral obesity and the risk of BE is entirely unknown.

Methods

We conducted a retrospective study in 163 patients with non-alcoholic fatty liver disease (NAFLD) who underwent both endoscopy and abdominal CT at an interval of less than a year at our institution. BE was endoscopically diagnosed based on the Prague C & M Criteria. The surface areas of visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) were calculated from CT images at the level of the umbilicus. The correlations between the BMI, VAT, and SAT and the risk of BE were examined by univariate and multivariate analyses.

Results

Sixty-nine of the 163 study participants (42.3%) were diagnosed to have endoscopic BE, which was classified as short-segment BE (SSBE) in almost all of the cases. There were no significant differences in the age or gender distribution between the groups with and without BE. According to the results of the univariate analysis, VAT was significantly associated with the risk of BE; the BMI tended to be higher in the group with BE than in the group without BE, but this relation did not reach statistical significance. VAT was independently associated with the risk of BE even after adjustment for the BMI.

Conclusion

In Japanese patients with NAFLD, obesity tended to be associated with the risk of BE, and this risk appeared to be mediated for the most part by abdominal visceral adiposity.

Treatment of nonalcoholic steatohepatitis with colestimide

AIM

To clarify the usefulness of colestimide in patients with nonalcoholic steatohepatitis (NASH) with hyperlipidemia.

METHODS

In an open-label randomized controlled trial, 17 NASH patients with hyperlipidemia received colestimide (3 g/day) for 24 weeks. There were 21 control patients. All patients received lifestyle modification therapy. Efficacy was assessed based on metabolic profile, insulin resistance, transaminases, serum hepatic fibrosis markers, adipokine levels, visceral fat on computed tomography (CT), and the fatty liver grade on CT. NASH patients with moderate to severe steatosis by histology were also evaluated separately.

RESULTS

Baseline clinical characteristics of the two groups were similar. Both groups experienced a significant decrease of BMI with no difference between them. However, visceral fat decreased significantly more in the colestimide group (P = 0.046). Aspartate aminotransferase (AST) showed a significantly greater decrease in the colestimide group compared with the control group (P = 0.042). In patients with moderate to severe histological steatosis, there were significant differences between the two groups regard to HbA(1c), transaminases, and hyaluronic acid (P = 0.018 for HbA(1c), P = 0.003 for AST, P = 0.042 for alanine aminotransferase, and P = 0.042 for hyaluronic acid). Steatosis significantly improved in patients in the colestimide group who had fatty liver on CT (P = 0.049). In the colestimide group, abdominal distension and/or constipation were seen, but mostly tolerable, no other clinical or laboratory adverse events associated with the use of this medicine were not observed.

CONCLUSIONS

Colestimide seems to increase the efficacy of lifestyle modification in NASH patients with hyperlipidemia. Its beneficial effects were more prominent in NASH patients with moderate to severe histological steatosis.

Adipocyte fatty acid binding protein levels relate to inflammation and fibrosis in nonalcoholic fatty liver disease

Several circulating cytokines are increased with obesity and may combine with the influence of visceral fat to generate insulin resistance, inflammation, and fibrosis in nonalcoholic fatty liver disease (NAFLD). Little information exists in NAFLD about three recently recognized tissue-derived cytokines that are all lipid-binding and involved in inflammation, namely adipocyte fatty acid-binding protein (AFABP), lipocalin-2, and retinol-binding protein 4 (RBP4). We examined the association of these three peptides with hepatic steatosis, inflammation, and fibrosis plus indices of adiposity, insulin resistance, and dyslipidaemia in 100 subjects with NAFLD and 129 matched controls. Levels of AFABP and lipocalin-2, but not RBP4, were significantly elevated in NAFLD versus control (AFABP, 33.5 +/- 14.4 versus 23.1 +/- 12.1 ng/mL [P < 0.001]; lipocalin-2, 63.2 +/- 26 versus 48.6 +/- 20 ng/mL [P < 0.001]) and correlated with indices of adiposity. AFABP correlated with indices of subcutaneous rather than visceral fat. AFABP alone distinguished steatohepatitis from simple steatosis (P= 0.02). Elevated AFABP independently predicted increasing inflammation and fibrosis, even when insulin resistance and visceral fat were considered; this applied to lobular inflammation and ballooning (odds ratio 1.4, confidence interval 1.0-1.8) and fibrosis stage (odds ratio 1.3, confidence interval 1.0-1.7) (P < or = 0.05 for all). None of the cytokines correlated with steatosis grade. AFABP levels correlated with insulin resistance (homeostasis model assessment of insulin resistance) in controls and NAFLD, whereas lipocalin-2 and RBP4 only correlated positively with insulin resistance in controls.

CONCLUSION

Circulating AFABP, produced by adipocytes and macrophages, and lipocalin-2, produced by multiple tissues, are elevated and may contribute to the metabolic syndrome in NAFLD. AFABP levels, which correlate with subcutaneous, but not visceral fat, independently predict inflammation and fibrosis in NAFLD and may have a direct pathogenic link to disease progression.

Effects of exercise and low-fat diet on adipose tissue inflammation and metabolic complications in obese mice

Adipose tissue inflammation causes metabolic disturbances, including insulin resistance and hepatic steatosis. Exercise training (EX) may decrease adipose tissue inflammation, thereby ameliorating such disturbances, even in the absence of fat loss. The purpose of this study was to 1) compare the effects of low-fat diet (LFD), EX, and their combination on inflammation, insulin resistance, and hepatic steatosis in high-fat diet-induced obese mice and 2) determine the effect of intervention duration (i.e., 6 vs. 12 wk). C57BL/6 mice (n = 109) fed a 45% fat diet (HFD) for 6 wk were randomly assigned to an EX (treadmill: 5 days/wk, 6 or 12 wk, 40 min/day, 65-70% Vo(2max)) or sedentary (SED) group. Mice remained on HFD or were placed on a 10% fat diet (LFD) for 6 or 12 wk. Following interventions, fat pads were weighed and expressed relative to body weight; hepatic steatosis was assessed by total liver triglyceride and insulin resistance by HOMA-IR and glucose AUC. RT-PCR was used to determine adipose gene expression of MCP-1, F4/80, TNF-alpha, and leptin. By 12 wk, MCP-1, F4/80, and TNF-alpha mRNA were reduced by EX and LFD. Exercise (P = 0.02), adiposity (P = 0.03), and adipose F4/80 (P = 0.02) predicted reductions in HOMA-IR (r(2) = 0.75, P < 0.001); only adiposity (P = 0.04) predicted improvements in hepatic steatosis (r(2) = 0.51, P < 0.001). Compared with LFD, EX attenuated increases in adiposity, hepatic steatosis, and adipose MCP-1 expression from 6 to 12 wk. There are unique metabolic consequences of a sedentary lifestyle and HFD that are most evident long term, highlighting the importance of both EX and LFD in preventing obesity-related metabolic disturbances.

Lifestyle-induced metabolic inflexibility and accelerated ageing syndrome: insulin resistance, friend or foe?

The metabolic syndrome may have its origins in thriftiness, insulin resistance and one of the most ancient of all signalling systems, redox. Thriftiness results from an evolutionarily-driven propensity to minimise energy expenditure. This has to be balanced with the need to resist the oxidative stress from cellular signalling and pathogen resistance, giving rise to something we call 'redox-thriftiness'. This is based on the notion that mitochondria may be able to both amplify membrane-derived redox growth signals as well as negatively regulate them, resulting in an increased ATP/ROS ratio. We suggest that 'redox-thriftiness' leads to insulin resistance, which has the effect of both protecting the individual cell from excessive growth/inflammatory stress, while ensuring energy is channelled to the brain, the immune system, and for storage. We also suggest that fine tuning of redox-thriftiness is achieved by hormetic (mild stress) signals that stimulate mitochondrial biogenesis and resistance to oxidative stress, which improves metabolic flexibility. However, in a non-hormetic environment with excessive calories, the protective nature of this system may lead to escalating insulin resistance and rising oxidative stress due to metabolic inflexibility and mitochondrial overload. Thus, the mitochondrially-associated resistance to oxidative stress (and metabolic flexibility) may determine insulin resistance. Genetically and environmentally determined mitochondrial function may define a 'tipping point' where protective insulin resistance tips over to inflammatory insulin resistance. Many hormetic factors may induce mild mitochondrial stress and biogenesis, including exercise, fasting, temperature extremes, unsaturated fats, polyphenols, alcohol, and even metformin and statins. Without hormesis, a proposed redox-thriftiness tipping point might lead to a feed forward insulin resistance cycle in the presence of excess calories. We therefore suggest that as oxidative stress determines functional longevity, a rather more descriptive term for the metabolic syndrome is the 'lifestyle-induced metabolic inflexibility and accelerated ageing syndrome'. Ultimately, thriftiness is good for us as long as we have hormetic stimuli; unfortunately, mankind is attempting to remove all hormetic (stressful) stimuli from his environment.

Nonalcoholic fatty liver disease in type 2 diabetes mellitus

PURPOSE OF REVIEW

To increase awareness about the close interrelationship between nonalcoholic fatty liver disease and type 2 diabetes mellitus, and of recent diagnostic and treatment advances in the field.

RECENT FINDINGS

The perception of nonalcoholic fatty liver disease as an uncommon and benign condition is rapidly changing. Approximately 70% of persons with type 2 diabetes mellitus have a fatty liver and the disease follows a more aggressive course with necroinflammation and fibrosis (i.e. nonalcoholic steatohepatitis) in diabetes. New evidence suggests that it is not steatosis per se but the development of lipotoxicity-induced mitochondrial dysfunction and activation of inflammatory pathways that leads to progressive liver damage. Nonalcoholic steatohepatitis is a leading cause of end-stage liver disease and contributes to cardiovascular disease in patients with type 2 diabetes mellitus. Because nonalcoholic steatohepatitis may develop even in the presence of normal liver transaminases, a liver biopsy is still necessary for a definitive diagnosis. However, new imaging methods and plasma biomarkers are emerging as alternative diagnostic tools. Lifestyle intervention is the gold standard for the management of nonalcoholic steatohepatitis. Recent randomized controlled trials suggest thiazolidiendiones are promising therapeutic agents.

SUMMARY

Nonalcoholic steatohepatitis is a frequently overlooked and potentially severe complication of type 2 diabetes mellitus. Patients may benefit from its early diagnosis and treatment.