Causes and metabolic consequences of Fatty liver

Hepatic Cholesterol-25-Hydroxylase Overexpression Improves Systemic Insulin Sensitivity in Mice

Obesity is a major risk factor for several diseases including diabetes, heart disease, and some forms of cancer and due to its rapidly increasing prevalence it has become one of the biggest problems medicine is facing today. All the more surprising, a substantial percentage of obese patients are metabolically healthy when classified based on insulin resistance and systemic inflammation. Oxysterols are naturally occurring molecules that play important role in various metabolic and inflammatory processes and their levels are elevated in patients suffering from obesity and diabetes. 25-Hydroxycholesterol (25-OHC) is produced in cells from cholesterol by the enzyme cholesterol 25-hydroxylase (Ch25h) and is involved in lipid metabolism, inflammatory processes, and cell proliferation. Here, we investigated the role of hepatic Ch25h in the transition from metabolically healthy obesity to insulin resistance and diabetes. Using several different experimental approaches, we demonstrated the significance of Ch25h on the border of "healthy" and "diseased" states of obesity. Adenovirus-mediated Ch25h overexpression in mice improved glucose tolerance and insulin sensitivity and lowered HOMA-IR. Our data suggest that low hepatic Ch25h levels could be considered a risk marker for unhealthy obesity.

Silymarin/Silybin and Chronic Liver Disease: A Marriage of Many Years

Silymarin is the extract of Silybum marianum, or milk thistle, and its major active compound is silybin, which has a remarkable biological effect. It is used in different liver disorders, particularly chronic liver diseases, cirrhosis and hepatocellular carcinoma, because of its antioxidant, anti-inflammatory and antifibrotic power. Indeed, the anti-oxidant and anti-inflammatory effect of silymarin is oriented towards the reduction of virus-related liver damages through inflammatory cascade softening and immune system modulation. It also has a direct antiviral effect associated with its intravenous administration in hepatitis C virus infection. With respect to alcohol abuse, silymarin is able to increase cellular vitality and to reduce both lipid peroxidation and cellular necrosis. Furthermore, silymarin/silybin use has important biological effects in non-alcoholic fatty liver disease. These substances antagonize the progression of non-alcoholic fatty liver disease, by intervening in various therapeutic targets: oxidative stress, insulin resistance, liver fat accumulation and mitochondrial dysfunction. Silymarin is also used in liver cirrhosis and hepatocellular carcinoma that represent common end stages of different hepatopathies by modulating different molecular patterns. Therefore, the aim of this review is to examine scientific studies concerning the effects derived from silymarin/silybin use in chronic liver diseases, cirrhosis and hepatocellular carcinoma.

Age at menarche is associated with the prevalence of non-alcoholic fatty liver disease later in life

BACKGROUND

The aim of the present study was to investigate whether age at menarche is associated with non-alcoholic fatty liver disease (NAFLD) later in life.

METHODS

The association between age at menarche and obesity, insulin resistance, and NAFLD after menopause was investigated in a cross-sectional study of 4128 postmenopausal Chinese women; NAFLD was diagnosed by hepatic ultrasound and information regarding age at menarche was collected using an interviewer-administered questionnaire.

RESULTS

Women with age at menarche <15 years had higher prevalence of overweight/obesity, insulin resistance, and NAFLD compared with women with age at menarche 15-18 or >18 years. Logistic regression revealed that women with earlier menarche had a higher risk for the age-adjusted prevalence of overweight/obesity, insulin resistance, and NAFLD, whereas later menarche showed a weaker, but still significant, association with a lower prevalence of NAFLD. However, further adjustment for some variables and current body mass index (BMI) or homeostasis model assessment of insulin resistance (HOMA-IR) attenuated the association between later menarche and a lower prevalence of NAFLD. A decreasing trend in the risk of NAFLD was seen across increasing levels of age at menarche (age-adjusted P_trend  < 0.001; multivariate-adjusted P_trend  < 0.001; multivariate + current BMI-adjusted P_trend  = 0.03; multivariate + HOMA-IR-adjusted P_trend  = 0.06).

CONCLUSION

Age at menarche is associated with the prevalence of NAFLD later in life, independent of BMI and insulin resistance.

Non-alcoholic fatty liver disease with and without metabolic syndrome: Different long-term outcomes

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) and metabolic syndrome (MetS) are both shown to increase the risk of cardiovascular diseases and type 2 diabetes. However, there is a great overlap between these two diseases. The present study was aimed to examine the cardiovascular and metabolic prognosis of non-alcoholic fatty liver disease with and without metabolic syndrome.

METHODS

Middle-aged subjects (n=958) were divided into four subgroups, those with NAFLD and MetS, those with NAFLD or MetS, and healthy controls. The baseline characteristics of the subgroups were analyzed. The follow-up time for cardiovascular events was about 16years. After approximately 21years the cardiac ultrasound and laboratory parameters were re-analyzed and new type 2 diabetes cases were recorded.

RESULTS

Those with both diseases were at the greatest risk for cardiovascular events (p<0.001). Compared to healthy controls, only those with MetS, with or without NAFLD, were at increased risk for the development of type 2 diabetes (p<0.001) and for an increase in left ventricular mass index (p=0.001 and p=0.005, respectively). The cardiovascular and metabolic risk in subjects with NAFLD only was quite similar to that in healthy controls. The I148M variant of the patatin-like phospholipase domain-containing 3 gene (PNPLA3 polymorphism) was most present in those with NAFLD only (p=0.008).

CONCLUSIONS

NAFLD with MetS implies a considerable risk for cardiovascular diseases, type 2 diabetes and the increase of left ventricular mass index whereas NAFLD without MetS does not.

Nonalcoholic Fatty Liver Disease Is Prevalent in Women With Prior Gestational Diabetes Mellitus and Independently Associated With Insulin Resistance and Waist Circumference

OBJECTIVE

Type 2 diabetes increases the risk of nonalcoholic fatty liver disease (NAFLD), which is a potentially reversible condition but is also associated with progressive fibrosis and cirrhosis. Women with prior gestational diabetes mellitus (pGDM) have a higher risk for NAFLD.

RESEARCH DESIGN AND METHODS

One hundred women without diabetes who had pGDM (median [interquartile range]: age 38.6 [6.4] years; BMI 31.0 [6.2] kg/m²) and 11 healthy control subjects without NAFLD (age 37.9 [7.8] years; BMI 28.1 [0.8] kg/m²) underwent a 75-g oral glucose tolerance test (OGTT), DXA whole-body scan, and ultrasonic evaluation of hepatic steatosis.

RESULTS

Twenty-four (24%) women with pGDM had NAFLD on the basis of the ultrasound scan. None had cirrhosis. Women with NAFLD had a higher BMI (P = 0.0002) and waist circumference (P = 0.0003), increased insulin resistance (P = 0.0004), and delayed suppression of glucagon after the OGTT (P < 0.0001), but NAFLD was not associated with the degree of glucose intolerance (P = 0.2196). Visceral fat mass differed among the three groups, with the NAFLD group having the highest amount of fat and the control subjects the lowest (P = 0.0003). By logistic regression analysis, insulin resistance (P = 0.0057) and waist circumference (P = 0.0109) were independently associated with NAFLD.

CONCLUSIONS

NAFLD was prevalent in this cohort of relatively young and nonseverely obese women with pGDM who are considered healthy apart from their increased risk for diabetes. Insulin resistance and a larger waist circumference were independently associated with the presence of NAFLD, whereas glucose intolerance was not.

Hepatic Overexpression of CD36 Improves Glycogen Homeostasis and Attenuates High-Fat Diet-Induced Hepatic Steatosis and Insulin Resistance

The common complications in obesity and type 2 diabetes include hepatic steatosis and disruption of glucose-glycogen homeostasis, leading to hyperglycemia. Fatty acid translocase (FAT/CD36), whose expression is inducible in obesity, is known for its function in fatty acid uptake. Previous work by us and others suggested that CD36 plays an important role in hepatic lipid homeostasis, but the results have been conflicting and the mechanisms were not well understood. In this study, by using CD36-overexpressing transgenic (CD36Tg) mice, we uncovered a surprising function of CD36 in regulating glycogen homeostasis. Overexpression of CD36 promoted glycogen synthesis, and as a result, CD36Tg mice were protected from fasting hypoglycemia. When challenged with a high-fat diet (HFD), CD36Tg mice showed unexpected attenuation of hepatic steatosis, increased very low-density lipoprotein (VLDL) secretion, and improved glucose tolerance and insulin sensitivity. The HFD-fed CD36Tg mice also showed decreased levels of proinflammatory hepatic prostaglandins and 20-hydroxyeicosatetraenoic acid (20-HETE), a potent vasoconstrictive and proinflammatory arachidonic acid metabolite. We propose that CD36 functions as a protective metabolic sensor in the liver under lipid overload and metabolic stress. CD36 may be explored as a valuable therapeutic target for the management of metabolic syndrome.

Association of coronary artery calcification with liver fibrosis in Japanese patients with non-alcoholic fatty liver disease

AIMS

Cardiovascular events are the leading cause of death among patients with non-alcoholic fatty liver disease (NAFLD), but their relationship remains unclear. This study examined the association between coronary atherosclerosis and liver fibrosis, represented by the coronary artery calcification (CAC) score and non-invasive fibrosis markers, respectively.

METHODS

Among 698 patients with chest pain or electrocardiographic abnormalities who underwent coronary computed tomography (CT) between April 2006 and March 2010, those with known liver disorders or history of emergency coronary angioplasty were excluded, leaving 366 patients for this study. Diagnosis of NAFLD was based on abdominal CT and history of alcohol consumption. Subjects with CAC of 100 AU or more were categorized into the high-risk group for cardiovascular events. Patient records were examined for clinical parameters including CAC score and non-invasive fibrosis marker FIB-4 index.

RESULTS

Ninety-four patients (25.7%) had NAFLD. In this group, univariate analysis identified old age, high diastolic blood pressure, high liver to spleen ratio and high FIB-4 index as risk factors for cardiovascular events and multivariate analysis identified age of 66 years or older and FIB-4 index of 2.09 or more as the significant risk factors. For the observation period until August 2014, the cumulative proportion of PCI performance was significantly higher in patients with FIB-4 of 2.09 or more than those with FIB-4 of less than 2.09.

CONCLUSION

The progression of arteriosclerosis and that of liver fibrosis may be associated in NAFLD patients. The FIB-4 index can be easily determined and thus can be a useful marker for predicting cardiovascular events in NAFLD patients.

Integrative transcriptomic analysis of NAFLD animal model reveals dysregulated genes and pathways in metabolism

Dysregulation of metabolism in hepatocytes leads to hepatic diseases such as hepatitis and non-alcoholic fatty liver disease (NAFLD). NAFLD represents a spectrum of liver diseases ranging from simple steatosis to nonalcoholic steatohepatitis (NASH). NASH is likely to progress to cirrhosis, liver failure and hepatocellular carcinoma, which lead to poor long-term prognosis. However, the exact mechanism of development of NAFLD is not well elucidated. In order to better understand the pathogenesis of NAFLD, we have performed an integrative analysis to livers from NAFLD rat models in a global view of the transcriptome. By systemic and integrative analyses, we have found that transport, angiogenesis and cell adhesion were upregulated in response to high fat diet feeding, which may cause a large amount of free fatty acid transport, hepatic fibrosis and hepatocytes injury. GO tree analysis has shown that angiogenesis was upregulated. GO term in response to high fat diet which may cause fibrosis. The pathway interaction network has indicated that upregulated "valine, leucine, and isoleucine metabolism" may decrease the serum concentration of branched-chain amino acid (BCAA). The enhanced degradation of BCAA in NAFLD animal models may lead to inhibition of the regeneration of hepatocytes, reducing the production of albumin, attenuating the inhibition of liver cancer and decreasing immunity. Overall, high fat diet upregulated a variety of metabolism which have converged at TCA cycle. High fatty has pushed the hepatic mitochondria to a "busy state". Comprehensively, genes participated in dysregulated biological process and metabolisms may be served as indicators for evaluation of NAFLD progression and therapeutic targets.

A Computational Model of Hepatic Energy Metabolism: Understanding Zonated Damage and Steatosis in NAFLD

In non-alcoholic fatty liver disease (NAFLD), lipid build-up and the resulting damage is known to occur more severely in pericentral cells. Due to the complexity of studying individual regions of the sinusoid, the causes of this zone specificity and its implications on treatment are largely ignored. In this study, a computational model of liver glucose and lipid metabolism is presented which treats the sinusoid as the repeating unit of the liver rather than the single hepatocyte. This allows for inclusion of zonated enzyme expression by splitting the sinusoid into periportal to pericentral compartments. By simulating insulin resistance (IR) and high intake diets leading to the development of steatosis in the model, we identify key differences between periportal and pericentral cells accounting for higher susceptibility to pericentral steatosis. Secondly, variation between individuals is seen in both susceptibility to steatosis and in its development across the sinusoid. Around 25% of obese individuals do not show excess liver fat, whilst 16% of lean individuals develop NAFLD. Furthermore, whilst pericentral cells tend to show higher lipid levels, variation is seen in the predominant location of steatosis from pericentral to pan-sinusoidal or azonal. Sensitivity analysis was used to identify the processes which have the largest effect on both total hepatic triglyceride levels and on the sinusoidal location of steatosis. As is seen in vivo, steatosis occurs when simulating IR in the model, predominantly due to increased uptake, along with an increase in de novo lipogenesis. Additionally, concentrations of glucose intermediates including glycerol-3-phosphate increased when simulating IR due to inhibited glycogen synthesis. Several differences between zones contributed to a higher susceptibility to steatosis in pericentral cells in the model simulations. Firstly, the periportal zonation of both glycogen synthase and the oxidative phosphorylation enzymes meant that the build-up of glucose intermediates was less severe in the periportal hepatocyte compartments. Secondly, the periportal zonation of the enzymes mediating β-oxidation and oxidative phosphorylation resulted in excess fats being metabolised more rapidly in the periportal hepatocyte compartments. Finally, the pericentral expression of de novo lipogenesis contributed to pericentral steatosis when additionally simulating the increase in sterol-regulatory element binding protein 1c (SREBP-1c) seen in NAFLD patients in vivo. The hepatic triglyceride concentration was predicted to be most sensitive to inter-individual variation in the activity of enzymes which, either directly or indirectly, determine the rate of free fatty acid (FFA) oxidation. The concentration was most strongly dependent on the rate constants for β-oxidation and oxidative phosphorylation. It also showed moderate sensitivity to the rate constants for processes which alter the allosteric inhibition of β-oxidation by acetyl-CoA. The predominant sinusoidal location of steatosis meanwhile was most sensitive variations in the zonation of proteins mediating FFA uptake or triglyceride release as very low density lipoproteins (VLDL). Neither the total hepatic concentration nor the location of steatosis showed strong sensitivity to variations in the lipogenic rate constants.

Phenotypes of prediabetes and stratification of cardiometabolic risk

Prediabetes is associated with increased risks of type 2 diabetes, cardiovascular disease, dementia, and cancer, and its prevalence is increasing worldwide. Lifestyle and pharmacological interventions in people with prediabetes can prevent the development of diabetes and possibly cardiovascular disease. However, prediabetes is a highly heterogeneous metabolic state, both with respect to its pathogenesis and prediction of disease. Improved understanding of these features and precise phenotyping of prediabetes could help to improve stratification of disease risk. In this Personal View, we focus on the extreme metabolic phenotypes of metabolically healthy obesity and metabolically unhealthy normal weight, insulin secretion failure, insulin resistance, visceral obesity, and non-alcoholic fatty liver disease. We present new analyses aimed at improving characterisation of phenotypes in lean, overweight, and obese people with prediabetes. We discuss evidence from lifestyle intervention studies to explore whether these phenotypes can also be used for individualised prediction and prevention of cardiometabolic diseases.

The multiple-hit pathogenesis of non-alcoholic fatty liver disease (NAFLD)

Nonalcoholic fatty liver disease (NAFLD) is increasingly prevalent and represents a growing challenge in terms of prevention and treatment. Despite its high prevalence, only a small minority of affected patients develops inflammation and subsequently fibrosis and chronic liver disease, while most of them only exhibit simple steatosis. In this context, the full understanding of the mechanisms underlying the development of NAFLD and non-alcoholic steatohepatitis (NASH) is of extreme importance; despite advances in this field, knowledge on the pathogenesis of NAFLD is still incomplete. The 'two-hit' hypothesis is now obsolete, as it is inadequate to explain the several molecular and metabolic changes that take place in NAFLD. The "multiple hit" hypothesis considers multiple insults acting together on genetically predisposed subjects to induce NAFLD and provides a more accurate explanation of NAFLD pathogenesis. Such hits include insulin resistance, hormones secreted from the adipose tissue, nutritional factors, gut microbiota and genetic and epigenetic factors. In this article, we review the factors that form this hypothesis.

A novel hepatokine, HFREP1, plays a crucial role in the development of insulin resistance and type 2 diabetes

AIMS/HYPOTHESIS

Type 2 diabetes is highly correlated with nonalcoholic fatty liver disease (NAFLD). Hepatocyte-derived fibrinogen-related protein 1 (HFREP1) is a hepatokine that mediates NAFLD development; however, the role of HFREP1 in the development of insulin resistance and diabetes remains obscure.

METHODS

A total of 193 age- and sex-matched participants with normal glucose tolerance, impaired fasting glucose (IFG), impaired glucose tolerance (IGT) and newly diagnosed diabetes (NDD) were recruited for a cross-sectional study. Plasma HFREP1 levels were measured and multivariate linear regression analysis was used to evaluate the relationship between HFREP1, IFG, IGT and NDD. The causal relationship between HFREP1 and insulin resistance was then investigated in animal and cell models. Glucose and insulin tolerance tests, and euglycaemic-hyperinsulinaemic clamp, were used to evaluate insulin sensitivity in animals with Hfrep1 overexpression or knockdown in liver by lentiviral vectors. HepG2 cells were used to clarify the possible mechanism of HFREP1-induced insulin resistance.

RESULTS

Plasma HFREP1 concentrations were significantly increased in participants with IFG, IGT and NDD. HFREP1 concentrations were independently associated with fasting plasma glucose levels, insulin resistance, IFG, IGT and NDD. Injection of recombinant HFREP1 or Hfrep1 overexpression induced insulin resistance in mice, and HFREP1 disrupted insulin signalling to induce insulin resistance through an extracellular signal-regulated kinase (ERK)1/2-dependent pathway. Moreover, hepatic knockdown of HFREP1 improved insulin resistance in both mice fed a high-fat diet and ob/ob mice.

CONCLUSIONS/INTERPRETATION

These findings highlight the crucial role of HFREP1 in insulin resistance and diabetes, and provide a potential strategy and biomarker for developing therapeutic approaches to combat these diseases.

Non-alcoholic fatty liver disease fibrosis score and preclinical vascular damage in morbidly obese patients

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is strongly related with enhanced morbidity and mortality from cardiovascular disease. In obese patients with both NAFLD and features of the metabolic syndrome, the cardiovascular risk is further increased.

AIM

The aim of this study is to investigate the relationship between severity of liver fibrosis evaluated by NAFLD fibrosis score (NAFLD-FS), Homeostatic Model Assessment of Insulin Resistance (HOMA-IR), other obesity-related markers and preclinical atherosclerosis in morbidly obese patients with previously diagnosed NAFLD.

METHODS

Laboratory parameters, visceral fat area (VFA), flow-mediated dilatation (FMD), intima-media thickness (IMT), HOMA-IR and NAFLD-FS were determined in 196 morbidly obese patients.

RESULTS

Patients with higher NAFLD-FS or HOMA-IR show higher left max-IMT and lower FMD (p<0.001). VFA and NAFLD-FS, but not HOMA-IR, were independent predictors of reduced FMD (respectively β -0.268, p=0.001 and β -0.165, p=0.039, p of the model<0.001) and increased left max-IMT (respectively β 0.165, p=0.031 and β 0.301, p<0.001, p of the model<0.001).

CONCLUSIONS

In morbidly obese patients, NAFLD-FS correlates with markers of early vascular damage. NAFLD-FS, easier to obtain than VFA, seems to be a better score than HOMA-IR to categorize such subjects who are potentially at risk of future cardiovascular events.

Epidemiology and natural history of non-alcoholic fatty liver disease

Non-alcoholic steatohepatitis (NASH) is part of the spectrum of non-alcoholic fatty liver disease (NAFLD) that leads to progressive liver disease and presents a growing challenge to public health. Because of the increased prevalence of metabolic syndrome and obesity, NAFLD and NASH have expanded to a substantial extent. In NASH patients, advanced fibrosis is the major predictor of morbidity and liver-related mortality, and an accurate diagnosis of NASH is mandatory. Although there is currently no validated test of serum biomarkers available to diagnose NASH, and histologic evaluation with a liver biopsy remains the gold standard, screening for fibrosis is recommended in patients with suspicion of NASH. Clinical prediction models and serum biomarkers for advanced fibrosis have relatively good negative predictive value and can be useful for screening. Also, transient elastography is increasingly available to estimate fibrosis in NASH. Therefore, due to the lack of a reliable and accepted non-invasive diagnostic modality, screening for NASH in the general population is not currently recommended. Better understanding of the natural history of NASH is needed to evaluate the utility and cost-effectiveness of screening.

Fatty liver is an independent predictor of early carotid atherosclerosis

BACKGROUND & AIMS

Whether steatosis is incidentally or causally associated with carotid atherosclerosis is debated, and long-term follow-up data are missing. This study aims to examine the impact of steatosis on the presence and progression of carotid intima-media thickness (C-IMT) and carotid plaques (CP) in a large cohort with longitudinal follow-up.

METHODS

A retrospective single-center study between 1995 and 2012. Transversal cohort: patients with ⩾2 cardiovascular risk factors without previous cardiovascular events. Longitudinal cohort: patients with two consecutive C-IMT measurements more than 2years apart. Steatosis was defined by a surrogate marker, the fatty liver index (FLI). CP and C-IMT were assessed by carotid ultrasound.

RESULTS

In the transversal cohort (n=5671) both C-IMT and the Framingham risk score (FRS) increased across FLI quartiles (0.58±0.12, 0.61±0.14, 0.63±0.14, 0.64±0.14mm, and 5±5%, 9±7%, 12±8%, 15±9%, p<0.001 for both). Steatosis predicted C-IMT better than diabetes or dyslipidemia. Steatosis independently predicted C-IMT (p=0.002) and FRS (p<0.001) after adjustment for metabolic syndrome and cardiovascular risk factors. In the longitudinal cohort (n=1872, mean follow-up 8±4years), steatosis occurred in 12% and CP in 23% of patients. C-IMT increased in patients with steatosis occurrence (from 0.60±0.13mm to 0.66±0.14mm, p=0.001) whereas it did not change in those that stayed free of steatosis. Steatosis at baseline predicted CP occurrence (OR=1.63, 95% CI 1.10-2.41, p=0.014), independent of age, sex, type-2 diabetes, tobacco use, hsCRP, hypertension and C-IMT.

CONCLUSIONS

In patients with metabolic syndrome at risk for cardiovascular events, steatosis contributes to early atherosclerosis and progression thereof, independent of traditional cardiovascular risk factors.

Branched-chain and aromatic amino acids, insulin resistance and liver specific ectopic fat storage in overweight to obese subjects

BACKGROUND & AIMS

Amino acids may interfere with insulin action, particularly in obese individuals. We hypothesized that increased circulating branched-chain and aromatic amino acids herald insulin resistance and ectopic fat storage, particularly hepatic fat accumulation.

METHODS AND RESULTS

We measured fasting branched-chain and aromatic amino acids (tryptophan, tyrosine, and phenylalanine) by mass spectrometry in 111 overweight to obese subjects. We applied abdominal magnetic resonance imaging and spectroscopy to assess adipose tissue distribution and ectopic fat storage, respectively. Plasma branched-chain amino acids concentrations were related to insulin sensitivity and intrahepatic fat independent from adiposity, age and gender, but not to abdominal adipose tissue or intramyocellular fat.

CONCLUSIONS

In weight stable overweight and obese individuals, branched-chain amino acid concentrations are specifically associated with hepatic fat storage and insulin resistance.

The AST/ALT (De-Ritis) ratio: A novel marker for critical limb ischemia in peripheral arterial occlusive disease patients

The aspartat aminotransferase (AST)/alanin aminotransferase (ALT) (De-Ritis) ratio (AAR) is an easily applicable blood test. An elevated AAR on the one hand has been associated with an increase in nonalcoholic fatty liver disease (NAFLD). NAFLD on the other hand is associated with an increase in cardiovascular disease, all-cause mortality, and diabetes. As the AAR is also elevated in case of muscular damage, we investigated AAR and its association with critical limb ischemia (CLI) in peripheral arterial occlusive disease (PAOD) patients.In our cross-sectional study, we included 1782 PAOD patients treated at our institution from 2005 to 2010. Patients with chronic alcohol consumption (>20 g/day) were excluded. AAR was calculated and the cohort was categorized into tertiles according to the AAR. An optimal cut-off value for the continuous AAR was calculated by applying a receiver operating curve analysis to discriminate between CLI and non-CLI.In our cohort, occurrence of CLI significantly increased with an elevation in AAR. As an optimal cut-off value, an AAR of 1.67 (sensitivity 34.1%, specificity 81.0%) was identified. Two groups were categorized, 1st group containing 1385 patients (AAR < 1.67) and a 2nd group with 397 patients (AAR > 1.67). CLI was more frequent in AAR > 1.67 patients (166 [41.9%]) compared to AAR < 1.67 patients (329 [23.8%]) (P < 0.001), as was prior myocardial infarction (28 [7.1%] vs 54 [3.9%], P = 0.01). Regarding inflammatory parameters, C-reactive protein (median 8.1 mg/L [2.9-28.23] vs median 4.3 mg/L [2.0-11.5]) and fibrinogen (median 427.5 mg/dL [344.25-530.0] vs 388.0 mg/dL [327.0-493.0]) also significantly differed in the 2 patient groups (both P < 0.001). Finally, an AAR > 1.67 was associated with an odds ratio (OR) of 2.0 (95% confidence interval [CI] 1.7-2.3) for CLI even after adjustment for other well-established vascular risk factors.An increased AAR is significantly associated with patients at high risk for CLI and other cardiovascular endpoints. The AAR is a broadly available and cheap marker, which might be useful to highlight patients at high risk for vascular endpoints.

Pathogenesis of Zika Virus-Associated Embryopathy

A strong causal association has become evident between Zika virus (ZIKV) infection during pregnancy and the occurrence of fetal growth restriction, microcephaly and eye defects. Circumstantial evidence is presented in this paper in support of the hypothesis that these effects, as well as the Guillain-Barré syndrome, are due to an endogenous form of hypervitaminosis A resulting from ZIKV infection-induced damage to the liver and the spillage of stored vitamin A compounds ("retinoids") into the maternal and fetal circulation in toxic concentrations. Retinoids are mainly stored in the liver (about 80%) and are essential for numerous biological functions. In higher concentration, retinoids are potentially cytotoxic, pro-oxidant, mutagenic and teratogenic, especially if sudden shifts occur in their bodily distribution. Although liver involvement has not been mentioned specifically in recent reports, conventional liver enzyme tests underestimate the true extent of liver dysfunction. The proposed model could be tested by comparing retinoid concentration and expression profiles in microcephalic newborns of ZIKV-infected mothers and nonmicrocephalic newborn controls, and by correlating these profiles with measures of clinical severity.

Early hypermethylation of hepatic Igfbp2 results in its reduced expression preceding fatty liver in mice

Obesity and ectopic fat disposition are risk factors for metabolic disease. Recent data indicate that IGFBP2 expression in liver is epigenetically inhibited during hepatic steatosis. The aim of this study was to investigate if epigenetic de-regulation of hepatic Igfbp2 occurs already early in life and is associated with increased risk for diet-induced obesity (DIO) during adolescence. Male C57BL/6J mice received a high-fat diet. After 3 weeks on this diet (age of 6 weeks), DIO-susceptible (responder, Resp) and DIO-resistant (non-responder, nResp) mice were identified by early weight gain. At the age of 6 weeks, Resp mice exhibited elevated blood glucose (p < 0.05), plasma insulin (p < 0.01), HOMA-IR and leptin/adiponectin ratio, whereas liver triglycerides were identical but significantly increased (p < 0.01) in Resp mice at 20 weeks of age. Igfbp2 expression was reduced in young Resp compared with nResp mice (p < 0.01), an effect that correlated with elevated DNA methylation of intronic CpG₂₆₀₅ (p < 0.01). The epigenetic inhibition of Igfbp2 was stable over time and preceded DIO and hepatosteatosis in adult mice. In vitro studies demonstrated that selective methylation of CpG₂₆₀₅ significantly reduced reporter activity by ∼85%, indicating that Igfbp2 expression is modulated by methylation. In human whole blood cells, methylation of IGFBP2 at the homologous CpG site was increased in obese men with impaired glucose tolerance. In conclusion, our data show that increased methylation of hepatic Igfbp2 during infancy predicts the development of fatty liver later in life and is linked to deterioration of glucose metabolism.

Exercise Intensity Modulates Glucose-Stimulated Insulin Secretion when Adjusted for Adipose, Liver and Skeletal Muscle Insulin Resistance

Little is known about the effects of exercise intensity on compensatory changes in glucose-stimulated insulin secretion (GSIS) when adjusted for adipose, liver and skeletal muscle insulin resistance (IR). Fifteen participants (8F, Age: 49.9±3.6yr; BMI: 31.0±1.5kg/m²; VO₂peak: 23.2±1.2mg/kg/min) with prediabetes (ADA criteria, 75g OGTT and/or HbA_1c) underwent a time-course matched Control, and isocaloric (200kcal) exercise at moderate (MIE; at lactate threshold (LT)), and high-intensity (HIE; 75% of difference between LT and VO₂peak). A 75g OGTT was conducted 1 hour post-exercise/Control, and plasma glucose, insulin, C-peptide and free fatty acids were determined for calculations of skeletal muscle (1/Oral Minimal Model; SM_IR), hepatic (HOMA_IR), and adipose (ADIPOSE_IR) IR. Insulin secretion rates were determined by deconvolution modeling for GSIS, and disposition index (DI; GSIS/IR; DI_SMIR, DI_HOMAIR, DI_ADIPOSEIR) calculations. Compared to Control, exercise lowered SM_IR independent of intensity (P<0.05), with HIE raising HOMA_IR and ADIPOSE_IR compared with Control (P<0.05). GSIS was not reduced following exercise, but DI_HOMAIR and DI_ADIPOSEIR were lowered more following HIE compared with Control (P<0.05). However, DI_SMIR increased in an intensity based manner relative to Control (P<0.05), which corresponded with lower post-prandial blood glucose levels. Taken together, pancreatic insulin secretion adjusts in an exercise intensity dependent manner to match the level of insulin resistance in skeletal muscle, liver and adipose tissue. Further work is warranted to understand the mechanism by which exercise influences the cross-talk between tissues that regulate blood glucose in people with prediabetes.

A Role for the Liver in Parturition and Preterm Birth

Neither the mechanisms of parturition nor the pathogenesis of preterm birth are well understood. Poor nutritional status has been suspected as a major causal factor, since vitamin A concentrations are low in preterm infants. However, even large enteral doses of vitamin A from birth fail to increase plasma concentrations of vitamin A or improve outcomes in preterm and/or extremely low birthweight infants. These findings suggest an underlying impairment in the secretion of vitamin A from the liver, where about 80% of the vitamin is stored. Vitamin A accumulates in the liver and breast during pregnancy in preparation for lactation. While essential in low concentration for multiple biological functions, vitamin A in higher concentration can be pro-oxidant, mutagenic, teratogenic and cytotoxic, acting as a highly surface-active, membrane-seeking and destabilizing compound. Regarding the mechanism of parturition, it is conjectured that by nine months of gestation the hepatic accumulation of vitamin A (retinol) from the liver is such that mobilization and secretion are impaired to the point where stored vitamin A compounds in the form of retinyl esters and retinoic acid begin to spill or leak into the circulation, resulting in amniotic membrane destabilization and the initiation of parturition. If, however, the accumulation and spillage of stored retinoids reaches a critical threshold prior to nine months, e.g., due to cholestatic liver disease, which is common in mothers of preterm infants, the increased retinyl esters and/or retinoic acid rupture the fetal membranes, inducing preterm birth and its complications, including retinopathy, necrotizing enterocolitis and bronchopulmonary dysplasia. Subject to testing, the model suggests that measures taken prior to and during pregnancy to improve liver function could reduce the risk of adverse birth outcomes, including preterm birth.

Effects of transcutaneous electrical stimulation of lower limb muscles on experimental fatty liver

BACKGROUND AND AIMS

Although the beneficial effects of exercise on fatty liver have been described, a previous study conducted at our department showed that transcutaneous electrical muscle stimulation (TEMS) of lower abdominal muscles aggravated fatty liver. The present study aims to evaluate the ability of TEMS of the lower limb muscles to improve fatty liver infiltration.

MATERIAL AND METHODS

Thirty male Wistar rats were randomly allocated into three groups: control; fructose-fed (F), fed fructose-enriched diet for 6weeks; and fructose-fed with transcutaneous electrical muscle stimulation (F+TEMS), fed fructose-enriched diet for 6weeks and lower limb muscles subjected to TEMS during the last 3weeks of feeding, five sessions/week. Body weight, length, body mass index (BMI), and abdominal and lower limb circumferences were all recorded. Fasting blood glucose, serum insulin, serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), total protein, serum albumin, high density lipoprotein cholesterol (HDL-C), triglyceride (TG), and total cholesterol (TC) levels were measured. LDL cholesterol (LDL-C) and the atherogenic index (AI) were calculated. Absolute and relative hepatic weights as well as histological examination of the liver were assessed.

RESULTS

Final body weight, abdominal and lower limb circumferences, absolute liver weight, homoeostasis model assessment (HOMA) score, and TG, LDL-C, AI, serum ALT, and AST levels were all significantly reduced in the (F+TEMS) group compared to the (F) group. There was a significant increase in GPx and HDL-C levels, HDL/LDL ratio, and total protein and serum albumin content in (F+TEMS) rats compared to (F) rats. Histologically, hepatic tissue from (F+TEMS) rats had minimal steatotic changes that were restricted to zone 1 and less marked inflammatory cell infiltration compared to (F) rats.

CONCLUSION

TEMS was able to reverse steatosis, hyperglycaemia, insulin resistance, dyslipidaemia, and fatty liver caused by fructose feeding. The study confirmed that the variation in the anatomical site of skeletal muscle contraction affects fatty liver in different ways.

Association between betatrophin/ANGPTL8 and non-alcoholic fatty liver disease: animal and human studies

Betatrophin/angiopoietin-like protein 8 (ANGPTL8) is a liver-secreted protein recently identified as a potent stimulator of beta cell proliferation in mice. However, it is unclear how betatrophin is regulated in humans with non-alcoholic fatty liver disease (NAFLD). We investigated the role of betatrophin in mice and in humans with and without NAFLD. Serum betatrophin levels were examined by ELISA in 164 subjects, including 96 patients with NAFLD. Levels were significantly elevated in subjects with NAFLD compared with controls (1.301 ± 0.617 vs. 0.900 ± 0.574 μg/L, P < 0.001), even after stratification by diabetic or obesity status. Circulating betatrophin positively correlated with obesity or glycemic indices, liver enzyme profiles, and NAFLD status, and was confirmed by multivariate regression analyses (β = 0.195, P = 0.040). However, when including insulin resistance index in the model, the significant association between betatrophin level and NAFLD was diminished due to a mediation effect of insulin resistance on this relationship. Palmitate or tunicamycin increased betatrophin expression in HepG2 cells, while a chemical chaperone blocked its induction. Hepatic expression of betatrophin was elevated in mice with NAFLD including db/db or ob/ob mice and mice with a high-fat or methionine-choline deficient diet. In conclusion, circulating betatrophin was increased in mice and humans with NAFLD and its expression was induced by endoplasmic reticulum stress in hepatocytes (Clinical trial no. NCT02285218).

Short-term aerobic exercise training improves gut peptide regulation in nonalcoholic fatty liver disease

Obesity-related nonalcoholic fatty liver disease (NAFLD) is now the most common chronic liver disease. Exercise and diet are uniformly prescribed treatments for NAFLD; however, there are limited empirical data on the effects of exercise training on metabolic function in these patients. The purpose of this study was to investigate the fasting and glucose-stimulated adaptation of gut peptides to short-term aerobic exercise training in patients with NAFLD. Twenty-two obese subjects, 16 with NAFLD [body mass index (BMI), 33.2 ± 1.1 (SE) kg/m(2)] and 6 obese controls (BMI, 31.3 ± 1.2 kg/m(2)), were enrolled in a supervised aerobic exercise program (60 min/day, 85% of their heart rate maximum, for 7 days). Fasting and glucose-stimulated glucagon-like peptide-1 (GLP-17-36) and peptide tyrosine tyrosine (PYYTotal) concentrations in plasma were assessed before and after the exercise program. Initially, the NAFLD group had higher fasting PYY (NAFLD = 117 ± 18.6, control = 47.2 ± 6.4 pg/ml, P < 0.05) and GLP-1 (NAFLD = 12.4 ± 2.2, control = 6.2 ± 0.2 pg/ml, P < 0.05) and did not significantly increase GLP-1 or PYY in response to glucose ingestion. After the exercise program, fasting GLP-1 was reduced in the NAFLD group (10.7 ± 2.0 pg/ml, P < 0.05). Furthermore, exercise training led to significant increase in the acute (0-30 min) PYY and GLP-1 responses to glucose in the NAFLD group, while the total area under the glucose-stimulated GLP-1 response curve was reduced in both NAFLD and controls (P < 0.05). In summary, 7 days of vigorous aerobic exercise normalized the dynamic PYY and GLP-1 responses to nutrient stimulation and reduced the GLP-1 response in NAFLD, suggesting that exercise positively modulates gut hormone regulation in obese adults with NAFLD.

β2-Adrenergic receptor ablation modulates hepatic lipid accumulation and glucose tolerance in aging mice

Catecholamines acting through β-adrenergic receptors (β(1)-, β(2)-, β(3)-AR subtypes) modulate important biological responses in various tissues. Our previous studies suggest a role for increased hepatic β-AR-mediated signaling during aging as a mediator of hepatic steatosis, liver glucose output, and insulin resistance in rodents. In the current study, we have utilized β(2)-AR knockout (KO) and wildtype (WT) control mice to define further the role of β(2)-AR signaling during aging on lipid and glucose metabolism. Our results demonstrate for the first time that age-related increases in hepatic triglyceride accumulation and body weight are attenuated upon β(2)-AR ablation. Although no differences in plasma triglyceride, non-esterified fatty acids or insulin levels were detected between old WT and KO animals, an age-associated increase in hepatic expression of lipid homeostasis regulator Cidea was significantly reduced in old KO mice. Interestingly, we also observed a shift from reduced glucose tolerance in young adult KO animals to significantly improved glucose tolerance in old KO when compared to age-matched WT mice. These results provide evidence for an important role played by β(2)-ARs in the regulation of lipid and glucose metabolism during aging. The effect of β(2)-AR ablation on caloric intake during aging is currently not known and requires investigation. Future studies are also warranted to delineate the β(2)-AR-mediated mechanisms involved in the control of lipid and glucose homeostasis, especially in the context of a growing aging population.

The role of immune cells in metabolism-related liver inflammation and development of non-alcoholic steatohepatitis (NASH)

The low grade inflammatory state present in obesity promotes the progression of Non-Alcoholic Fatty Liver Disease (NAFLD). In Non-Alcoholic Steatohepatitis (NASH), augmented hepatic steatosis is accompanied by aberrant intrahepatic inflammation and exacerbated hepatocellular injury. NASH is an important disorder and can lead to fibrosis, cirrhosis and even neoplasia. The pathology of NASH involves a complex network of mechanisms, including increased infiltration of different subsets of immune cells, such as monocytes, T-lymphocytes and neutrophils, to the liver, as well as activation and in situ expansion of liver resident cells such as Kupffer cells or stellate cells. In this review, we summarize recent advances regarding understanding the role of the various cells of the innate and adaptive immunity in NASH development and progression, and discuss possible future therapeutic options and tools to interfere with disease progression.

Sex Hormone-Binding Globulin in Children and Adolescents

Sex hormone-binding globulin (SHBG) is a circulating glycoprotein that transports testosterone and other steroids in the blood. Interest in SHBG has escalated in recent years because of its inverse association with obesity and insulin resistance, and because many studies have linked lower circulating levels of SHBG to metabolic syndrome, type 2 diabetes, nonalcoholic fatty liver disease, polycystic ovary syndrome, and early puberty. The purpose of this review is to summarize molecular, clinical, endocrine, and epidemiological findings to illustrate how measurement of plasma SHBG may be useful in clinical medicine in children.

Muscle and liver-specific alterations in lipid and acylcarnitine metabolism after a single bout of exercise in mice

Intracellular lipid pools are highly dynamic and tissue-specific. Physical exercise is a strong physiologic modulator of lipid metabolism, but most studies focus on changes induced by long-term training. To assess the acute effects of endurance exercise, mice were subjected to one hour of treadmill running, and (13)C16-palmitate was applied to trace fatty acid incorporation in soleus and gastrocnemius muscle and liver. The amounts of carnitine, FFA, lysophospholipids and diacylglycerol and the post-exercise increase in acetylcarnitine were pronouncedly higher in soleus than in gastrocnemius. In the liver, exercise increased the content of lysophospholipids, plasmalogens and carnitine as well as transcript levels of the carnitine transporter. (13)C16-palmitate was detectable in several lipid and acylcarnitine species, with pronounced levels of tracer-derived palmitoylcarnitine in both muscles and a strikingly high incorporation into triacylglycerol and phosphatidylcholine in the liver. These data illustrate the high lipid storing activity of the liver immediately after exercise whereas in muscle, fatty acids are directed towards oxidation. The observed muscle-specific differences accentuate the need for single-muscle analyses as well as careful consideration of the particular muscle employed when studying lipid metabolism in mice. In addition, our results reveal that lysophospholipids and plasmalogens, potential lipid signalling molecules, are acutely regulated by physical exercise.

Glucose-Raising Polymorphisms in the Human Clock Gene Cryptochrome 2 (CRY2) Affect Hepatic Lipid Content

Circadian rhythms govern vital functions. Their disruption provokes metabolic imbalance favouring obesity and type-2 diabetes. The aim of the study was to assess the role of clock genes in human prediabetes. To this end, genotype-phenotype associations of 121 common single nucleotide polymorphisms (SNPs) tagging ARNTL, ARNTL2, CLOCK, CRY1, CRY2, PER1, PER2, PER3, and TIMELESS were assessed in a study population of 1,715 non-diabetic individuals metabolically phenotyped by 5-point oral glucose tolerance tests. In subgroups, hyperinsulinaemic-euglycaemic clamps, intravenous glucose tolerance tests, and magnetic resonance imaging/spectroscopy were performed. None of the tested SNPs was associated with body fat content, insulin sensitivity, or insulin secretion. Four CRY2 SNPs were associated with fasting glycaemia, as reported earlier. Importantly, carriers of these SNPs’ minor alleles revealed elevated fasting glycaemia and, concomitantly, reduced liver fat content. In human liver tissue samples, CRY2 mRNA expression was directly associated with hepatic triglyceride content. Our data may point to CRY2 as a novel switch in hepatic fuel metabolism promoting triglyceride storage and, concomitantly, limiting glucose production. The anti-steatotic effects of the glucose-raising CRY2 alleles may explain why these alleles do not increase type-2 diabetes risk.

Nonalcoholic Fatty Liver Disease and Mean Platelet Volume: A Systemic Review and Meta-analysis

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is linked to obesity, metabolic syndrome, and cardiovascular disease. Increased mean platelet volume (MPV), a marker of platelet activity, is associated with acute myocardial infarction, stroke, thrombosis, and increased mortality after myocardial infarction. The purpose of this study was to perform a meta-analysis to investigate the relationship between NAFLD and MPV.

METHODOLOGY

A systematic search of MEDLINE (Ovid), PubMed, and CINAHL databases from 1950 to May 2014, complemented with manual review of references of published articles for studies comparing MPV in patients with and without NAFLD was done. Results were pooled using both fixed and random effects model.

RESULTS

Our analysis from pooling of data from 8 observational studies including 1428 subjects (NAFLD=842 and non-NAFLD=586) showed that MPV was significantly higher in patients with NAFLD than those without. The standardized mean difference in MPV between NAFLD and controls was 0.457 (95% confidence interval: 0.348-0.565, P<0.001) using fixed and 0.612 (95% confidence interval: 0.286-0.938, P<0.001) using random effects model.

CONCLUSIONS

This study suggests that MPV is significantly higher in patients with NAFLD, indicating the presence of increased platelet activity in such patients. Future research is needed to investigate whether this increased MPV is associated with increased cardiovascular disease in patients with NAFLD.

Fatty liver disease: Disparate predictive ability for cardiometabolic risk and all-cause mortality

AIM: To assess the association of a surrogate of fatty liver disease (FLD) with incident type-2 diabetes, coronary heart disease, and all-cause mortality.

METHODS: In a prospective population-based study on 1822 middle-aged adults, stratified to gender, we used an algorithm of fatty liver index (FLI) to identify associations with outcomes. An index ≥ 60 indicated the presence of FLD. In Cox regression models, adjusted for age, smoking status, high-density lipoprotein cholesterol, and systolic blood pressure, we assessed the predictive value of FLI for incident diabetes, coronary heart disease (CHD), and all-cause mortality.

RESULTS: At a mean 8 year follow-up, 218 and 285 incident cases of diabetes and CHD, respectively, and 193 deaths were recorded. FLD was significantly associated in each gender with blood pressure, total cholesterol, apolipoprotein B, uric acid, and C-reactive protein; weakly with fasting glucose; and inversely with high-density lipoprotein-cholesterol and sex hormone-binding globulin. In adjusted Cox models, FLD was (with a 5-fold HR) the major determinant of diabetes development. Analyses further disclosed significant independent prediction of CHD by FLD in combined gender [hazard ratio (HR) = 1.72, 95% confidence interval (CI): 1.17-2.53] and men (HR = 2.35, 95%CI: 1.25-4.43). Similarly-adjusted models for all-cause mortality proved, however, not to confer risk, except for a tendency in prediabetics and diabetic women.

CONCLUSION: A surrogate of FLD conferred significant high risk of diabetes and coronary heart disease, independent of some metabolic syndrome traits. All-cause mortality was not associated with FLD, except likely in the prediabetic state. Such a FLI may reliably be used in epidemiologic studies.

Increased visceral adiposity with normal weight is associated with the prevalence of non-alcoholic fatty liver disease in Japanese patients with type 2 diabetes

AIMS/INTRODUCTION

To investigate the impact of increased visceral adiposity with normal weight (OB[-]VA[+]) on the prevalence of non-alcoholic fatty liver disease in patients with type 2 diabetes.

MATERIALS AND METHODS

This was a cross-sectional study of 140 Japanese patients with type 2 diabetes (mean age 65 ± 11 year; 44.6% women). Visceral fat area (VFA; cm(2) ) and liver attenuation index (LAI) were assessed by abdominal computed tomography. The patients were divided into four groups by VFA and body mass index (BMI; kg/m(2) ) as follows: BMI <25 kg/m(2) and VFA <100 cm(2) (OB[-]VA[-]), BMI ≥25 kg/m(2) and VFA <100 cm(2) (OB[+]VA[-]), BMI <25 kg/m(2) and VFA ≥100 cm(2) (OB[-]VA[+]), and BMI ≥25 kg/m(2) and VFA ≥100 cm(2) (OB[+]VA[+]). Multivariate linear regression and logistic regression analysis were carried out to determine the impact of OB(-)VA(+) on LAI.

RESULTS

In the present study, 25.0% were OB(-)VA(+) patients, where the LAI levels were lower (1.09 ± 0.22) than those in OB(-)VA(-) patients (1.23 ± 0.15), and were equivalent to those in OB(+)VA(+) patients (1.03 ± 0.26). In multivariate linear regression analysis, OB(-)VA(+) was independently associated with LAI (standardized β-0.212, P = 0.014). In multivariate logistic regression analysis, OB(-)VA(+) was a significant predictor of LAI <0.9 (odds ratio 5.88, 95% confidence interval 1.03-33.52, P = 0.046).

CONCLUSIONS

The present study provides evidence that increased visceral adiposity with normal weight is a strong predictor for the prevalence of non-alcoholic fatty liver disease in Japanese patients with type 2 diabetes.

Impact of Nonalcoholic Fatty Liver Disease on Myocardial Perfusion in Nondiabetic Patients Undergoing Primary Percutaneous Coronary Intervention for ST-Segment Elevation Myocardial Infarction

Limited data exist on the role of nonalcoholic fatty liver disease (FLD) as a potential independent risk factor in the setting of acute coronary syndromes. The aim of this study was to evaluate the impact of FLD on myocardial perfusion and inhospital major adverse cardiac events (MACE) in the setting of ST-elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (PCI). We examined 186 consecutive nondiabetic patients (mean age 58 ± 11 years and 76% men) who underwent primary PCI for STEMI by ultrasound within 72 hours of admission. FLD was graded according to a semiquantitative severity score as mild (score <3) or moderate to severe (score ≥3). Myocardial perfusion was determined by measuring myocardial blush grade (MBG) and ST-segment resolution (STR) analysis. Patients were divided into 2 groups according to FLD score (<3 or ≥3). There were no differences with regard to postprocedural Thrombolysis In Myocardial Infarction 3 flow grade between the 2 groups (89% vs 83%, p = 0.201). Patients with FLD score ≥3 were more likely to have absent myocardial perfusion (MBG 0/1, 37% vs 12%, p <0.0001), absent STR (27% vs 9%, p = 0.001), and higher inhospital MACE rate (31% vs 8%, p <0.0001). By multivariate analysis, FLD ≥3 score was found to be an independent predictor of absent MBG 0/1 (odds ratio [OR] 2.856, 95% confidence interval [CI] 1.214 to 6.225, p = 0.033), absent STR (OR 2.862, 95% CI 1.242 to 6.342, p = 0.031), and inhospital MACE (OR 2.454, 95% CI 1.072 to 4.872, p = 0.048). In conclusion, we found that despite similar high rates of Thrombolysis In Myocardial Infarction 3 after primary PCI, patients with FLD score ≥3 are more likely to have impaired myocardial perfusion which may contribute to adverse inhospital outcome.

Variation in the Phosphoinositide 3-Kinase Gamma Gene Affects Plasma HDL-Cholesterol without Modification of Metabolic or Inflammatory Markers

Objective

Phosphoinositide 3-kinase γ (PI3Kγ) is a G-protein-coupled receptor-activated lipid kinase mainly expressed in leukocytes and cells of the cardiovascular system. PI3Kγ plays an important signaling role in inflammatory processes. Since subclinical inflammation is a hallmark of atherosclerosis, obesity-related insulin resistance, and pancreatic β-cell failure, we asked whether common genetic variation in the PI3Kγ gene (PIK3CG) contributes to body fat content/distribution, serum adipokine/cytokine concentrations, alterations in plasma lipid profiles, insulin sensitivity, insulin release, and glucose homeostasis.

Study Design

Using a tagging single nucleotide polymorphism (SNP) approach, we analyzed genotype-phenotype associations in 2,068 German subjects genotyped for 10 PIK3CG SNPs and characterized by oral glucose tolerance tests. In subgroups, data from hyperinsulinaemic-euglycaemic clamps, magnetic resonance spectroscopy of the liver, whole-body magnetic resonance imaging, and intravenous glucose tolerance tests were available, and peripheral blood mononuclear cells (PBMCs) were used for gene expression analysis.

Results

After appropriate adjustment, none of the PIK3CG tagging SNPs was significantly associated with body fat content/distribution, adipokine/cytokine concentrations, insulin sensitivity, insulin secretion, or blood glucose concentrations (p>0.0127, all; Bonferroni-corrected α-level: 0.0051). However, six non-linked SNPs displayed at least nominal associations with plasma HDL-cholesterol concentrations, two of them (rs4288294 and rs116697954) reaching the level of study-wide significance (p = 0.0003 and p = 0.0004, respectively). More precisely, rs4288294 and rs116697954 influenced HDL2-, but not HDL3-, cholesterol. With respect to the SNPs’ in vivo functionality, rs4288294 was significantly associated with PIK3CG mRNA expression in PBMCs.

Conclusions

We could demonstrate that common genetic variation in the PIK3CG locus, possibly via altered PIK3CG gene expression, determines plasma HDL-cholesterol concentrations. Since HDL2-, but not HDL3-, cholesterol is influenced by PIK3CG variants, PI3Kγ may play a role in HDL clearance rather than in HDL biogenesis. Even though the molecular pathways connecting PI3Kγ and HDL metabolism remain to be further elucidated, this finding could add a novel aspect to the pathophysiological role of PI3Kγ in atherogenesis.

Age- and Gender Dependent Liver Fat Content in a Healthy Normal BMI Population as Quantified by Fat-Water Separating DIXON MR Imaging

OBJECTIVES

To establish age- and sex-dependent values of magnetic resonance (MR) liver fat-signal fraction (FSF) in healthy volunteers with normal body-mass index (BMI).

METHODS

2-point mDIXON sequences (repetition time/echo time, 4.2msec/1.2msec, 3.1msec) at 3.0 Tesla MR were acquired in 80 healthy volunteers with normal BMI (18.2 to 25.7 kg/m2) between 20 and 62 years (10 men/10 women per decade). FSF was measured in 5 liver segments (segment II, III, VI, VII, VIII) based on mean signal intensities in regions of interest placed on mDIXON-based water and fat images. Multivariate general linear models were used to test for significant differences between BMI-corrected FSF among age subgroups. Pearson and Spearman correlations between FSF and several body measures were calculated.

RESULTS

Mean FSF (%) ± standard deviations significantly differed between women (3.91 ± 1.10) and men (4.69 ± 1.38) and varied with age for women/men (p-value: 0.002/0.027): 3.05 ± 0.49/3.74 ± 0.60 (age group 20-29), 3.75 ± 0.66/4.99 ± 1.30 (30-39), 4.76 ± 1.16/5.25 ± 1.97 (40-49) and 4.09 ± 1.26/4.79 ± 0.93 (50-62). FSF differences among age subgroups were significant for women only (p = 0.003).

CONCLUSIONS

MR-based liver fat content is higher in men and peaks in the fifth decade for both genders.

Endocrine causes of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in the industrialized world. The prevalence of NAFLD is increasing, becoming a substantial public health burden. NAFLD includes a broad spectrum of disorders, from simple conditions such as steatosis to severe manifestations such as fibrosis and cirrhosis. The relationship of NAFLD with metabolic alterations such as type 2 diabetes is well described and related to insulin resistance, with NAFLD being recognized as the hepatic manifestation of metabolic syndrome. However, NAFLD may also coincide with endocrine diseases such as polycystic ovary syndrome, hypothyroidism, growth hormone deficiency or hypercortisolism. It is therefore essential to remember, when discovering altered liver enzymes or hepatic steatosis on radiological exams, that endocrine diseases can cause NAFLD. Indeed, the overall prognosis of NAFLD may be modified by treatment of the underlying endocrine pathology. In this review, we will discuss endocrine diseases that can cause NALFD. Underlying pathophysiological mechanisms will be presented and specific treatments will be reviewed.

Adipose Tissue Dysfunction and Altered Systemic Amino Acid Metabolism Are Associated with Non-Alcoholic Fatty Liver Disease

Background

Fatty liver is a major cause of obesity-related morbidity and mortality. The aim of this study was to identify early metabolic alterations associated with liver fat accumulation in 50- to 55-year-old men (n = 49) and women (n = 52) with and without NAFLD.

Methods

Hepatic fat content was measured using proton magnetic resonance spectroscopy (¹H MRS). Serum samples were analyzed using a nuclear magnetic resonance (NMR) metabolomics platform. Global gene expression profiles of adipose tissues and skeletal muscle were analyzed using Affymetrix microarrays and quantitative PCR. Muscle protein expression was analyzed by Western blot.

Results

Increased branched-chain amino acid (BCAA), aromatic amino acid (AAA) and orosomucoid were associated with liver fat accumulation already in its early stage, independent of sex, obesity or insulin resistance (p<0.05 for all). Significant down-regulation of BCAA catabolism and fatty acid and energy metabolism was observed in the adipose tissue of the NAFLD group (p<0.001for all), whereas no aberrant gene expression in the skeletal muscle was found. Reduced BCAA catabolic activity was inversely associated with serum BCAA and liver fat content (p<0.05 for all).

Conclusions

Liver fat accumulation, already in its early stage, is associated with increased serum branched-chain and aromatic amino acids. The observed associations of decreased BCAA catabolism activity, mitochondrial energy metabolism and serum BCAA concentration with liver fat content suggest that adipose tissue dysfunction may have a key role in the systemic nature of NAFLD pathogenesis.

The Crosstalk between Hypoxia and Innate Immunity in the Development of Obesity-Related Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) has become a major health issue in western countries in parallel with the dramatic increase in the prevalence of obesity and all obesity related conditions, including respiratory diseases as obstructive sleep apnea-hypopnea syndrome (OSAHS). Interestingly, the severity of the liver damage in obesity-related NAFLD has been associated with the concomitant presence of OSAHS. In the presence of obesity, the proinflammatory state in these patients together with intermittent episodes of hypoxia, characteristic of OSAHS pathogenesis, may lead to an enhanced inflammatory response mediated by a positive feedback loop mechanism that implicates HIF-1 and NFκB. Thus, the severity of liver involvement in obese NAFLD patients with a concomitant diagnosis of OSAHS could be explained. In this review, we focus on the molecular mechanisms underlying the hepatic response to chronic intermittent hypoxia and its interaction with innate immunity in obesity-related NAFLD.

Liver fat, statin use, and incident diabetes: The Multi-Ethnic Study of Atherosclerosis

BACKGROUND AND AIMS

To balance competing cardiovascular benefits and metabolic risks of statins, markers of type 2 diabetes (T2D) susceptibility are needed. We sought to define a competing risk/benefit of statin therapy on T2D and cardiovascular disease (CVD) events using liver attenuation and coronary artery calcification (CAC).

METHODS AND RESULTS

3153 individuals from the Multi-Ethnic Study of Atherosclerosis (MESA) without CVD, T2D/impaired fasting glucose, or baseline statin therapy had CT imaging for CAC and hepatic attenuation (hepatic steatosis). Cox models and rates of CVD and T2D were calculated to assess the role of liver attenuation in T2D and the relative risks/benefits of statins on CVD and T2D. 216 T2D cases were diagnosed at median 9.1 years follow-up. High liver fat and statin therapy were associated with diabetes (HR 2.06 [95%CI 1.52-2.79, P < 0.0001] and 2.01 [95%CI 1.46-2.77, P < 0.0001], respectively), after multivariable adjustment. With low liver fat and CAC = 0, the number needed to treat (NNT) for statin to prevent one CVD event (NNT 218) was higher than the number needed to harm (NNH) with an incident case of T2D (NNH 68). Conversely, those with CAC >100 and low liver fat were more likely to benefit from statins for CVD reduction (NNT 29) relative to T2D risk (NNH 67). Among those with CAC >100 and fatty liver, incremental reduction in CVD with statins (NNT 40) was less than incremental risk increase for T2D (NNH 24).

CONCLUSIONS

Liver fat is associated with incident T2D and stratifies competing metabolic/CVD risks with statin therapy. Hepatic fat may inform T2D surveillance and lipid therapeutic strategies.

Mechanistic link between nonalcoholic fatty liver disease and cardiometabolic disorders

Nonalcoholic fatty liver disease (NAFLD) is a chronic condition characterized by fat accumulation combined with low-grade inflammation in the liver. A large body of clinical and experimental data shows that increased flux of free fatty acids from increased visceral adipose tissue can lead to NAFLD related with insulin resistance. Thus, individuals with obesity, insulin resistance, and dyslipidemia are at the greatest risk of developing NAFLD. Conversely, NAFLD is one of the phenotypes of insulin resistance or metabolic syndrome. Many researchers have discovered a close association between NAFLD and insulin resistance, and focused on the role of NAFLD in the development of type 2 diabetes. Further, substantial evidence has suggested the association between NAFLD and cardiovascular disease (CVD). In the current review, we provide a plausible mechanistic link between NAFLD and CVD and the potential of the former as a therapeutic target based on pathophysiology. We also discuss in detail about the role of insulin resistance, oxidative stress, low-grade inflammation, abnormal lipid metabolism, gut microbiota, changes of biomarkers, and genetic predisposition in the pathological linking between NAFLD and cardiometabolic disorders.

Type 2 diabetes alters metabolic and transcriptional signatures of glucose and amino acid metabolism during exercise and recovery

AIMS/HYPOTHESIS

The therapeutic benefit of physical activity to prevent and treat type 2 diabetes is commonly accepted. However, the impact of the disease on the acute metabolic response is less clear. To this end, we investigated the effect of type 2 diabetes on exercise-induced plasma metabolite changes and the muscular transcriptional response using a complementary metabolomics/transcriptomics approach.

METHODS

We analysed 139 plasma metabolites and hormones at nine time points, and whole genome expression in skeletal muscle at three time points, during a 60 min bicycle ergometer exercise and a 180 min recovery phase in type 2 diabetic patients and healthy controls matched for age, percentage body fat and maximal oxygen consumption (VO2).

RESULTS

Pathway analysis of differentially regulated genes upon exercise revealed upregulation of regulators of GLUT4 (SLC2A4RG, FLOT1, EXOC7, RAB13, RABGAP1 and CBLB), glycolysis (HK2, PFKFB1, PFKFB3, PFKM, FBP2 and LDHA) and insulin signal mediators in diabetic participants compared with controls. Notably, diabetic participants had normalised rates of lactate and insulin levels, and of glucose appearance and disappearance, after exercise. They also showed an exercise-induced compensatory regulation of genes involved in biosynthesis and metabolism of amino acids (PSPH, GATM, NOS1 and GLDC), which responded to differences in the amino acid profile (consistently lower plasma levels of glycine, cysteine and arginine). Markers of fat oxidation (acylcarnitines) and lipolysis (glycerol) did not indicate impaired metabolic flexibility during exercise in diabetic participants.

CONCLUSIONS/INTERPRETATION

Type 2 diabetic individuals showed specific exercise-regulated gene expression. These data provide novel insight into potential mechanisms to ameliorate the disturbed glucose and amino acid metabolism associated with type 2 diabetes.

Adiposity and cancer risk: new mechanistic insights from epidemiology

Excess body adiposity, commonly expressed as body mass index (BMI), is a risk factor for many common adult cancers. Over the past decade, epidemiological data have shown that adiposity-cancer risk associations are specific for gender, site, geographical population, histological subtype and molecular phenotype. The biological mechanisms underpinning these associations are incompletely understood but need to take account of the specificities observed in epidemiology to better inform future prevention strategies.

Central effects of humanin on hepatic triglyceride secretion

Humanin (HN) is an endogenous mitochondria-associated peptide that has been shown to protect against various Alzheimer's disease-associated insults, myocardial ischemia-reperfusion injury, and reactive oxygen species-induced cell death. We have shown previously that HN improves whole body glucose homeostasis by improving insulin sensitivity and increasing glucose-stimulated insulin secretion (GSIS) from the β-cells. Here, we report that intraperitoneal treatment with one of HN analogs, HNG, decreases body weight gain, visceral fat, and hepatic triglyceride (TG) accumulation in high-fat diet-fed mice. The decrease in hepatic TG accumulation is due to increased activity of hepatic microsomal triglyceride transfer protein (MTTP) and increased hepatic TG secretion. Both intravenous (iv) and intracerebroventricular (icv) infusion of HNG acutely increase TG secretion from the liver. Vagotomy blocks the effect on both iv and icv HNG on TG secretion, suggesting that the effects of HNG on hepatic TG flux are centrally mediated. Our data suggest that HN is a new player in central regulation of peripheral lipid metabolism.

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.