Causes and metabolic consequences of Fatty liver

Circulating FGF21 Levels in Human Health and Metabolic Disease

Human fibroblast growth factor 21 (FGF21) is primarily produced and secreted by the liver as a hepatokine. This hormone circulates to its target tissues (e. g., brain, adipose tissue), which requires two components, one of the preferred FGF receptor isoforms (FGFR1c and FGFR3c) and the co-factor beta-Klotho (KLB) to trigger downstream signaling pathways. Although targeting FGF21 signaling in humans by analogues and receptor agonists results in beneficial effects, e. g., improvements in plasma lipids and decreased body weight, it failed to recapitulate the improvements in glucose handling shown for many mouse models. FGF21's role and metabolic effects in mice and its therapeutic potential have extensively been reviewed elsewhere. In this review we focus on circulating FGF21 levels in humans and their associations with disease and clinical parameters, focusing primarily on obesity and obesity-associated diseases such as type-2 diabetes. We provide a comprehensive overview on human circulating FGF21 levels under normal physiology and metabolic disease. We discuss the emerging field of inactivating FGF21 in human blood by fibroblast activation protein (FAP) and its potential clinical implications.

Metabolomic Characteristics of Fatty Pancreas

Objective Pancreatic steatosis is associated with impaired beta cell function in patients with prediabetes. The pathomechanisms underlying this association still remain to be elucidated. Recent data show that adipocytes are situated within the pancreatic parenchyma and therefore give raise to hypothesize that pancreatic fat together with known and unknown metabolites such as hepatokines affect insulin secretion. Applying a targeted metabolomic approach we investigated possible circulating markers of pancreatic fat in order to better understand its role in the pathophysiology of impaired beta cell function.

Methods We included 361 Caucasians, at increased risk of type 2 diabetes, from the Tübingen Family Study. All participants underwent a frequently sampled oral glucose tolerance test to assess insulin secretion and a magnetic resonance imaging to quantify pancreatic fat content, total body fat and visceral fat. Among the 152 subjects with prediabetes (IFG and/or IGT), two groups each with 20 individuals, having the lowest and highest pancreatic fat content were selected. The groups were matched for sex, age, BMI, total fat content, visceral fat content, liver fat content and insulin sensitivity. Metabolites were analyzed using the AbsoluteIDQ® p400 HR Kit by Biocrates.

Results Pancreatic fat content of all 152 subjects with prediabetes was negatively associated with insulin secretion represented by AUCC-peptide 0–120/AUCGlucose 0–120 (p=0.04; β=− 3.24). Furthermore, pancreatic fat content was positively associated with BMI, total body and visceral fat (all p<0.005). Levels of aminoacids, biogenic amines and monosaccharides were similar between the groups with high/low pancreatic fat content (p>0.90). Also, levels of polar lipids such as lysophosphatidylcholines, phosphatidylcholines, sphingomyelins and ceramides did not differ significantly between the groups (p>0.90). Investigating the levels of neutral lipids such as aclycarnitines, diglycerides, triglycerides and cholesteryl esters also revealed no differences between the groups (p>0.90).

Conclusion The amount of pancreatic fat is not associated with the metabolomic pattern in individuals with prediabetes. This might be due to the relatively low pancreatic fat content compared to the total amount of fat stored in other depots. The impact of pancreatic steatosis on insulin secretion might be mediated by paracrine effects which cannot be detected in the circulation.

Tissue Changes in the Development of Fatty Liver by Chronic Ingestion of Sucrose Associated with Obesity and Dyslipidemia in Rats

A diet high in sucrose, which is a common food constituent, induces obesity and non- alcoholic fatty liver (NFLD) caused by high caloric intake; however, it is important to investigate those sequential changes in the hepatic parenchyma related to sugar consumption which are associated to obesity and dyslipidemia. We analyzed the effects of long-term sucrose intake on fatty liver development, by the administration of 30% sucrose in drinking water in healthy Wistar rats during 30 weeks. Serum variables, body fat index, caloric intake and microscopic examination of liver tissue were monitored. In the first week, grade 1 steatosis was observed with ballooned hepatocytes, with a caloric intake of 125 ± 1.90 kcal / day / 100 g of body weight; together with a gain of 71% in abdominal fat with respect to the control group and dyslipidemia. During the 10 to 20 weeks period, steatosis grade 2 with noticeable inflammation (steatohepatitis), polymorphic cells and ballooned hepatocytes were evident. After 10 weeks, the caloric intake was 72.9 ± 5.99 kcal / day / 100 g of body weight with 199% of gain in abdominal fat in SUC groups with respect control group (p < 0.01) and moderate dyslipidemia; while after 20 weeks, the caloric intake was 61.6 ± 4.65 kcal / day / 100 g of body weight with 208% of gain in abdominal fat and also moderate dyslipidemia. After 30 weeks steatosis grade 3 with marked inflammation (steatohepatitis), periportal fibrosis, globose and fat-filled hepatocytes were observed, with a caloric intake of 52.3 ± 3.05 kcal / day / 100 g of body weight and 232% of gain in abdominal fat that was related to severe dyslipidemia. In conclusion, the sequential changes in the development of NAFLD were associated with the ingestion of sucrose and obesity since the first week of administration.

Non-alcoholic fatty liver disease: causes, diagnosis, cardiometabolic consequences, and treatment strategies

The prevalence of non-alcoholic fatty liver disease (NAFLD) is increasing worldwide. In some patients with NAFLD, isolated steatosis can progress to advanced stages with non-alcoholic steatohepatitis (NASH) and fibrosis, increasing the risk of cirrhosis and hepatocellular carcinoma. Furthermore, NAFLD is believed to be involved in the pathogenesis of common disorders such as type 2 diabetes and cardiovascular disease. In this Review, we highlight novel concepts related to diagnosis, risk prediction, and treatment of NAFLD. First, because NAFLD is a heterogeneous disease, the advanced stages of which seem to be strongly affected by comorbidities such as insulin resistance and type 2 diabetes, early use of reliable, non-invasive diagnostic tools is needed, particularly in patients with insulin resistance or diabetes, to allow the identification of patients at different disease stages. Second, although the strongest genetic risk alleles for NAFLD (ie, the 148Met allele in PNPLA3 and the 167Lys allele in TM6SF2) are associated with increased liver fat content and progression to NASH and cirrhosis, these alleles are also unexpectedly associated with an apparent protection from cardiovascular disease. If consistent across diverse populations, this discordance in NAFLD-related risk prediction between hepatic and extrahepatic disease might need to be accounted for in the management of NAFLD. Third, drug treatments assessed in NAFLD seem to differ with respect to cardiometabolic and antifibrotic efficacy, suggesting the need to better identify and tailor the most appropriate treatment approach, or to use a combination of approaches. These emerging concepts could contribute to the development of a multidisciplinary approach for endocrinologists and hepatologists working together in the management of NAFLD.

Crosstalk between nonalcoholic fatty liver disease and cardiometabolic syndrome

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 and de novo lipogenesis can lead to NAFLD and insulin resistance. Thus, individuals with obesity, insulin resistance, and dyslipidaemia are at the greatest risk of developing NAFLD. Conversely, NAFLD is a phenotype of cardiometabolic syndrome. Notably, researchers have discovered a close association between NAFLD and impaired glucose metabolism and focused on the role of NAFLD in the development of type 2 diabetes. Moreover, recent studies provide substantial evidence for an association between NAFLD and atherosclerosis and cardiometabolic disorders. Even if NAFLD can progress into severe liver disorders including nonalcoholic steatohepatitis (NASH) and cirrhosis, the majority of subjects with NAFLD die from cardiovascular disease eventually. In this review, we propose a potential pathological link between NAFLD/NASH and cardiometabolic syndrome. The potential factors that can play a pivotal role in this link, such as inflammation, insulin resistance, alteration in lipid metabolism, oxidative stress, genetic predisposition, and gut microbiota are discussed.

Effects of aerobic exercise training on the risk factors for liver diseases in elderly women with obesity and impaired fasting glucose: A pilot study

[Purpose]

In the present pilot study, we aimed to investigate the effects of the Silverrobics exercise program, which is similar to aerobic dance, on the factors related to glucose metabolism and liver enzymes.

[Methods]

Eight elderly women with obesity and impaired fasting glucose participated in the Silverrobics exercise program (60 minutes per session for five times a week for 8 weeks). The program was conducted at 50–60% of the heart rate reserve at 1 to 2 weeks and at 60–80% of the heart rate reserve at 3 to 8 weeks. To verify the effect of this 8-week exercise program on glucose metabolism and liver enzymes, blood analysis at pre- and post-training was performed.

[Results]

After the Silverrobics exercise program, there were significant decreases in the glucose (p<0.05), glycated hemoglobin A1c (p<0.05), 1,5-anhydroglucitol (p<0.05), and insulin levels (p<0.01) and homeostatic model assessment of insulin resistance score (p<0.05). However, there were no significant effects on the liver enzymes, except for alkaline phosphatase. The alkaline phosphatase level increased after the Silverrobics exercise program (p<0.05).

[Conclusion]

Although the Silverrobics exercise program had no beneficial effects on the liver enzymes, it may play an important role in preventing liver diseases considering the effects on glucose metabolism.

Association between ADIPOQ G276T and C11377G polymorphisms and the risk of non-alcoholic fatty liver disease: An updated meta-analysis

Background

Nonalcoholic fatty liver disease (NAFLD) is a significant contributor to global hepatic disorders. ADIPOQ gene single‐nucleotide polymorphisms have been associated with NAFLD susceptibility, but with inconsistent results across the studies. This study aimed to investigate the association between ADIPOQ polymorphisms (+276G>T, rs1501299 and −11377C>G, rs266729) and the risk of NAFLD.

Methods

PubMed, Embase, Wanfang, Web of Science, and China National Knowledge Infrastructure databases were used to identify the relevant published literature. Statistical analyses were calculated with STATA 11.0 software and RevMan 5.2. Summary odds ratios (OR) and 95% confidence intervals (CIs) were generated to assess the strength of the associations.

Results

Eleven relevant articles with a total of 3,644 participants (1,847 cases/1,797 controls) were included. Our meta‐analysis results revealed that ADIPOQ gene +276G>T polymorphism was not associated with NAFLD under various genetic models (allele model: OR = 0.99, 95% CI [0.69, 1.41]; dominant model: OR = 1.06, 95% CI [0.71, 1.58]; recessive model: OR = 0.83, 95% CI [0.42, 1.65]; homozygous model: OR = 0.86, 95% CI [0.38, 1.95]; heterozygous model: OR = 1.10, 95% CI [0.80, 1.53]; respectively). Moreover, no statistical significant association was found between +276G>T and NAFLD risk in the subgroups. ADIPOQ gene −11377C>G polymorphism significantly increased the risk of NAFLD (allele model: OR = 1.49, 95% CI [1.28, 1.75]; dominant model: OR = 1.64, 95% CI [1.35, 1.99]; recessive model: OR = 1.77, 95% CI [1.16, 2.70]; homozygous model: OR = 2.13, 95% CI [1.38, 3.28]; heterozygous model: OR = 1.58, 95% CI [1.29, 1.93]; respectively).

Conclusion

ADIPOQ gene −11377C>G may be a risk factor for NAFLD, while there was no association between ADIPOQ gene +276G>T polymorphism and the risk of NAFLD. Further studies are needed to detect the relationship between these ADIPOQ polymorphisms and NAFLD.

Dietary Sources of Fructose and Its Association with Fatty Liver in Mexican Young Adults

Fructose intake has been associated with non-alcoholic fatty liver disease (NAFLD). The objective of this study was to assess the consumption of dietary fructose according to: 1) classification of hepatic steatosis by two indexes and 2) diagnosis of NAFLD by MRI. We conducted a cross-sectional analysis among 100 young adults from Mexico City. The Hepatic Steatosis Index (HSI) and the Fatty Liver Index (FLI) were estimated using Body Mass Index (BMI), waist circumference, and fasting concentrations of glucose, triglycerides, and hepatic enzymes (ALT, AST, GGT). A semi-quantitative food frequency questionnaire was administered to obtain dietary sources of fructose. We estimated the concordance between the hepatic indices and NAFLD and the correlation between the index scores and the percentage of liver fat. Eighteen percent presented NAFLD; 44% and 46% were classified with hepatic steatosis according to HSI and FLI, respectively. We compared dietary intake of fructose by each outcome: HSI, FLI, and NAFLD. Sugar-sweetened beverages (SSB) and juices were consumed significantly more by those with steatosis by FLI and NAFLD suggesting that SSB intake is linked to metabolic alterations that predict the risk of having NAFLD at a young age.

Non-alcoholic steatohepatitis aggravates nitric oxide synthase inhibition-induced arteriosclerosis in SHRSP5/Dmcr rat model

Non-alcoholic steatohepatitis (NASH) is linked to increased cardiovascular risk, independent of the broad spectrum of metabolic syndrome risk factors. Stroke-prone (SP) spontaneously hypertensive rats (SHRSP5/Dmcr) fed a high-fat and high-cholesterol (HFC) diet developed hepatic lesions similar to those in human NASH pathology. These rats simultaneously developed lipid deposits in the mesenteric arteries, cardiac fibrosis, endothelial dysfunction and left ventricle (LV) diastolic dysfunction. However, the intermediary factors between NASH and cardiovascular disease are still unknown. We investigated whether NASH aggravates nitric oxide (NO) synthase inhibition-induced arteriosclerosis in SHRSP5/Dmcr rats. Wistar Kyoto and SHRSP5/Dmcr rats were divided into 4 groups of 5 and fed the stroke-prone (SP) or HFC diets for 8 weeks. To induce NO synthase inhibition, N^ω -nitro-L-arginine methyl ester hydrochloride (L-NAME) mixed with drinking water was administered in the final 2 weeks. The NASH+L-NAME group demonstrated the following characteristics related to arteriosclerosis and myocardial ischaemia: (a) LV systolic dysfunction with asynergy, (b) replacement fibrosis caused by the shedding of cardiomyocytes and (c) arterial lipid deposition and coronary occlusion secondary to endothelial dysfunction. These characteristics were not observed in the NASH or non-NASH+L-NAME groups. The SHRSP5/Dmcr rat model demonstrates that NASH significantly aggravates cardiovascular risk.

Effects of exercise training on Fetuin-a in obese, type 2 diabetes and cardiovascular disease in adults and elderly: a systematic review and Meta-analysis

Background

Elevated levels of fetuin-A are associated with increased risks of metabolic syndrome, type 2 diabetes and nonalcoholic fatty liver disease. This meta-analysis investigated whether exercise interventions can reduce fetuin-A in adults.

Methods

We searched clinical trials that objectively assessed fetuin-A and included study arms with exercise intervention. The pre-intervention and post-intervention data were used for meta-analysis. The effect sizes were calculated as standardized mean differences or changes in fetuin-A and expressed as Hedges’ g using random-effects models.

Results

The overall Hedges’ g for fetuin-A in all included interventions was − 0.640 (95%CI − 1.129 to − 0.151; n = 9), but this effect was not observed in obese (g = − 0.096; 95%CI, − 0.328 to 0.135) and type 2 diabetes/dysglycemia (g = − 0.56; 95%CI, − 1.348 to 0.236) individuals. Additionally, the random-effects meta-regression analysis showed that there was not a greater decrease in fetuin-A in individuals who achieved greater body mass index reductions (regression coefficient = 0.065; 95%CI, − 0.185 to 0.315).

Conclusion

Supervised exercise is associated with reductions in fetuin-A levels in adults and elderly. However, the results of the present meta-analysis should be interpreted with caution because of the variety of type of exercises and individual obesity related-disorders involve. Therefore, additional high-quality randomized controlled trials describing the effect of supervised exercise interventions on fetuin-A in adults are still needed. 

Electronic supplementary material

The online version of this article (10.1186/s12944-019-0962-2) contains supplementary material, which is available to authorized users.

Coenzyme Q10 attenuates high-fat diet-induced non-alcoholic fatty liver disease through activation of the AMPK pathway

Coenzyme Q10 regulates lipid metabolism to ameliorate the progression of NAFLD by activating the AMPK pathway.

Transient Elastography and Controlled Attenuation Parameter (CAP) in the Assessment of Liver Steatosis in Severe Adult Growth Hormone Deficiency

Non-alcoholic fatty liver disease (NAFLD) is common in patients with growth hormone deficiency (GHD). Some noninvasive techniques have been used to quantify liver fat, such as the controlled attenuation parameter (CAP). Objective: To evaluate CAP as a tool to identify liver steatosis and its relationship with different clinical and biochemical metabolic parameters in a group of patients with severe adult growth hormone deficiency (AGHD), and to compare the evolution of metabolic profiles after 6 months of human growth hormone (rhGH) replacement therapy in a subgroup of patients. Methods: Cross-sectional observational study at baseline of naive rhGH multiple pituitary hormonal deficiency (MPHD) hypopituitarism patients. A 6-month intervention clinical trial in a selected group of a non-randomized, non-controlled cohort was also applied. Results: Liver stiffness measurement (LSM) was normal in severe AGHD patients. CAP evaluation showed steatosis in 36.3% of baseline patients (8/22), associated with higher BMI, waist circumference, insulin, and alanine aminotransferase (ALT) levels. According to steatosis degree by CAP, child-onset growth hormone deficiency (CO-GHD) was graded as 68.75% (11/16) S0, 12.5% (2/16) S1, and 18.75% (3/16) S3, whereas AO-GHD was graded as 50% (3/6) S0, 16.66% (1/6) S2, and 33.33% S3. After 6 months of hrGH replacement, CAP measurements did not change significantly, neither on group without hepatic steatosis at baseline (194.4 ± 24.3 vs. 215.4 ± 51.3; p = 0.267) nor on the group with hepatic steatosis (297.2 ± 32.3 vs. 276.4 ± 27.8; p = 0.082). A significant improvement of body composition was observed only in the first group. Conclusions: We have demonstrated the importance of CAP as a non-invasive tool in the liver steatosis identification on hypopituitary patients. This method may be an important indicator of the severity of metabolic disorders in MPHD patients. In our study, no liver health modification in LSM at baseline or after 6 months of rhGH replacement was found. Longer studies can help to establish the potential repercussions of growth hormone replacement therapy on liver steatosis.

Development of the Metabolic Syndrome: Study Design and Baseline Data of the Lufthansa Prevention Study (LUPS), A Prospective Observational Cohort Survey

The Lufthansa Prevention Study (LUPS) study is a prospective observation of a healthy worker cohort to identify early changes in metabolism leading to the Metabolic Syndrome (MetS) and to analyze their relation to behavioral factors like nutrition, physical activity, psychological status, and to underlying genetic conditions. The LUPS study recruited a sample of 1.962 non-diabetic healthy adults between 25-60 years, employed at a flight base of Lufthansa Technik GmbH in Hamburg, Germany. Baseline assessments included anthropometric measures, blood and urine samples and medical history. Psychosocial variables, dietary habits and life-style risk factors were assessed via self-reported questionnaires.In this report we describe the study design and present baseline parameters including the prevalence of the MetS using different classification criteria. The MetS was present in 20% of male and 12% of female subjects according to the 'Harmonizing the metabolic syndrome' definition. The prevalence varies between 2.6% in male and 2.3% in female subjects up to 48% in male and 41% in female subjects according to different classification criteria of MetS.In conclusion, this first cross-sectional view on the LUPS data confirms the expectation that this cohort is rather healthy and thus provides the opportunity to analyze early changes associated with the development of the MetS. The LUPS study is registered as a clinical trial NCT01313156.

Long-term effects of increased protein intake after weight loss on intrahepatic lipid content and implications for insulin sensitivity: a PREVIEW study

The aim of this study was to assess the effects of a weight maintenance period comprising two diets differing in protein intake, after weight loss, on intrahepatic lipid content and implications for insulin sensitivity. A total of 25 participants [body mass index (BMI): 31.1 (3.5 kg/m²; intrahepatic lipid (IHL): 8.7 (8.3%; fasting glucose: 6.4 (0.6 mmol/l; homeostatic model assessment for insulin resistance (HOMA-IR): 3.7 (1.6; Matsuda index: 3.4 (2.9] started an 8-wk low-energy diet followed by a 2-yr weight maintenance period with either high protein or medium protein dietary guidelines. At baseline, after 6 mo, and after 2 yr, IHL, visceral adipose tissue (VAT), and subcutaneous adipose tissue (SAT) were determined by magnetic resonance spectroscopy/imaging. Glucose and insulin concentrations, determined during an oral glucose challenge, were used to assess the HOMA-IR and Matsuda insulin sensitivity index (ISI). Protein intake was measured with 24-h urinary nitrogen excretion. Protein intake, BMI, IHL, VAT, SAT, HOMA-IR, and ISI did not change differently between the groups during the intervention. In the whole group, BMI, IHL, VAT, SAT, HOMA-IR, and ISI were favorably changed at 6 mo and 2 yr compared with baseline ( P < 0.05). Mixed-model analysis showed that independent of BMI, protein intake (g/d) at 6 mo was inversely related to IHL (coefficient: -0.04; P < 0.05) and VAT (coefficient: -0.01; P < 0.05). Overall, IHL was positively related to HOMA-IR (coefficient: 0.10; P < 0.01) and inversely related to ISI (coefficient: -0.17; P < 0.01), independent of BMI. A 2-yr medium- to high-protein energy-restricted diet reduced IHL and VAT. Independently of changes in BMI, IHL was inversely related to insulin sensitivity.

Association between body mass index and fatty liver risk: A dose-response analysis

Body mass index (BMI) is associated with fatty liver risk, however, the dose-response relationship between continuous BMI changes and fatty liver risk has not been clearly defined. In this study, a cross-sectional study was conducted and a total of 3202 individuals were included. Unconditional logistic regression and restricted cubic spline model were used to analyze the dose-response association of BMI with fatty liver risk. After adjusting for confounding factors (age, gender, hypertension, total cholesterol, triglycerides, glucose, high-density lipoprotein, low-density lipoprotein, uric acid, homocysteine, creatinine, aspartate aminotransferase and alanine transaminase), overweight (OR = 3.55, 95% CI: 2.49–5.06, P = 2.79 × 10⁻¹²), obesity (OR = 7.59, 95% CI: 4.91–11.71, P = 6.56 × 10⁻²⁰) were significantly related to fatty liver risk. Stratified by gender (male/female), age (<50 years/≥50 years), prevalence of hypertension (yes/no), the above association was still significant (P = 0.004 or lower). In dose-response analysis, BMI was statistically significantly associated with fatty liver risk in a nonlinear fashion (approximately J-shaped fashion, P_nonlinearity = 1.71 × 10⁻⁴ or lower) in the total population and all subgroups mentioned above. Findings from this dose-response analysis suggest that higher BMI (overweight/obesity) is an independent, dose-dependent risk factor for fatty liver, and prevention of fatty liver focusing on continuous changes in BMI should be noted.

Adiposity and Diabetes Risk in Adults with Prediabetes: Heterogeneity of Findings Depending on Age and Anthropometric Measure

OBJECTIVE

The study aimed to evaluate the effect of age on diabetes incidence by general and central adiposity after 3-year follow-up in adults with prediabetes.

METHODS

Data were taken from a cohort of 1,184 subjects with prediabetes included in The Cohort Study in Primary Health Care on the Evolution of Patients with Prediabetes (PREDAPS). General adiposity was defined using body mass index (BMI), and central adiposity was defined with waist circumference and waist to height ratio. Data were analyzed by age groups 30 to 59 and 60 to 74 years. The association between adiposity and diabetes incidence was assessed using hazard ratios (HR).

RESULTS

Adjusting for sociodemographic characteristics, lifestyles, and metabolic parameters, diabetes HR for central adiposity based on the waist circumference clinical cutoff were 2.14 (1.12-4.09) and 1.48 (0.80-2.74) for people aged 30 to 59 and 60 to 74 years, respectively. In the model additionally adjusted for BMI, diabetes HR were 2.65 (1.24-5.65) and 1.33 (0.68-2.59), respectively. The use of a 1-SD increase rather than cutoff points did not alter this pattern. Similar findings were observed with central adiposity based on waist to height ratio.

CONCLUSIONS

The association of central adiposity with type 2 diabetes incidence was lower for people in the older age group than for those in the younger age group.

Female Dietary Patterns and the Pathogenesis of NAFLD

In Europe as well as the United States, nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease and is strongly associated with obesity and type 2 diabetes mellitus (T2DM). Nonalcoholic fatty liver disease is defined as a hepatic manifestation of the metabolic syndrome. Being a very powerful and independent cardiovascular risk factor, NAFLD increases cardiovascular and overall mortality to a significant degree. The purpose of this review was to determine sex- and gender-specific differences in the prevalence and pathogenesis of NAFLD and delineate the specific characteristics of NAFLD as a systemic disease in men and women. Postmenopausal women and women with endocrine disorders such as the polycystic ovarian syndrome are at high risk of developing NAFLD. The increasing incidence of female NAFLD after menopause appears to be related to reduced estrogen and increased testosterone levels, as well as changes in the distribution of fatty tissue. Finally, the role of gender-specific nutrition patterns in the pathogenesis of NAFLD will be discussed. Fructose consumption from industrialized products is a promoter of NAFLD, depending on the total daily calorie intake of macronutrients. A higher level of health literacy and conscious food behavior have been noted among women of all age groups compared to males, which could play a role in the pathogenesis of NAFLD. Health professionals are confronted with the challenges of early diagnosis by the use of sensitive, reliable, and noninvasive diagnostic tools, including screening algorithms for high-risk persons and providing gender-specific nutritional support as a crucial element of treatment and disease prevention.

Role of osteoprotegerin/receptor activator of nuclear factor kappa B/receptor activator of nuclear factor kappa B ligand axis in nonalcoholic fatty liver disease

Concomitantly with the increase in the prevalences of overweight/obesity, nonalcoholic fatty liver disease (NAFLD) has worldwide become the main cause of chronic liver disease in both adults and children. Patients with fatty liver display features of metabolic syndrome (MetS), like insulin resistance (IR), glucose intolerance, hypertension and dyslipidemia. Recently, epidemiological studies have linked obesity, MetS, and NAFLD to decreased bone mineral density and osteoporosis, highlighting an intricate interplay among bone, adipose tissue, and liver. Osteoprotegerin (OPG), an important symbol of the receptor activator of nuclear factor-B ligand/receptor activator of nuclear factor kappa B/OPG system activation, typically considered for its role in bone metabolism, may also play critical roles in the initiation and perpetuation of obesity-related comorbidities. Clinical data have indicated that OPG concentrations are associated with hypertension, left ventricular hypertrophy, vascular calcification, endothelial dysfunction, and severity of liver damage in chronic hepatitis C. Nonetheless, the relationship between circulating OPG and IR as a key feature of MetS as well as between OPG and NAFLD remains uncertain. Thus, the aims of the present review are to provide the existent knowledge on these associations and to discuss briefly the underlying mechanisms linking OPG and NAFLD.

Increased Pancreatic Echogenicity with US: Relationship to Glycemic Progression and Incident Diabetes

Purpose To evaluate the association between increased pancreatic echogenicity (IPE) and the risk of glycemic progression and incident diabetes. Materials and Methods This retrospective study was approved by the institutional review board, with waiver of informed consent. Consecutive individuals who had undergone abdominal ultrasonography as part of a health examination at a tertiary hospital between January 2005 and December 2011 were included. IPE was defined as increased echogenicity of the pancreas compared with that of the left lobe of liver. Glycemic progression was defined as the development of new prediabetes or diabetes in normoglycemic participants or as new diabetes in prediabetic participants during the follow-up period (median, 3.17 years; interquartile range, 2.01-4.67 years). The occurrence of incident diabetes, defined as a new diagnosis of diabetes during follow-up, was also analyzed. Results Mean age of the 32 346 participants was 50.4 years ± 12.2, and 48% (15 489 of 32 346) were female. The prevalence of IPE and nonalcoholic fatty liver disease (NAFLD) was 8.4% (2720 of 32 346) and 41.4% (13 389 of 32 346), respectively. A total of 8856 participants were included in the follow-up analysis. During the 29 819.2 person-years of follow-up, 1217 (13.7%) and 449 (5.1%) of the 8856 participants developed glycemic progression and new diabetes, respectively. IPE was associated with more glycemic progression (hazard ratio, 1.54; 95% confidence interval: 1.23, 1.92; P < .001) and incident diabetes (hazard ratio, 1.49; 95% confidence interval: 1.05, 2.11; P = .024) after adjustment for confounders, HbA_1c concentration, and NAFLD. Conclusion Increased pancreatic echogenicity is associated with deteriorating glycemic parameters and higher risk of glycemic progression and incident diabetes, independent of HbA_1c concentration and NAFLD. ^© RSNA, 2018 Online supplemental material is available for this article.

Severity of nonalcoholic fatty liver disease is associated with subclinical cerebro-cardiovascular atherosclerosis risk in Korean men

BACKGROUND

No studies have reported the relationship between nonalcoholic fatty liver disease (NAFLD) and concurrent cerebral artery and coronary artery atherosclerosis simultaneously. We aimed at determining whether NAFLD, as assessed by ultrasound, is associated with subclinical cerebro-cardio vascular atherosclerosis (CCVA) by multidetector-row computed tomography (MDCT), and high resolution-magnetic resonance angiography (HR-MRA). This cross-sectional study included men in the general Korean population aged 20-70 years.

RESULTS

A total of 1,652 men participated in the study (normal, n = 835; mild-to-moderate NAFLD, n = 512; severe NAFLD, n = 305). The risk of subclinical CCVA was positively associated with age (odds ratio [OR] 1.068; 1.054-1.081, p < 0.001), body mass index (OR 1.120; 1.08 0-1.162, p < 0.001), hepatic enzyme levels (OR 1.012; 1.001-1.023, p = 0.027; OR 1.006; 1.001-1.012, p = 0.036), fasting glucose (OR 1.021; 1.015-1.027, p < 0.001), triglycerides (OR 1.002; 1.000-1.003, p = 0.016), hypertension (OR 2.836; 2.268-3.546, p < 0.001), and diabetes (OR 2.911; 2.137-3.964, p < 0.001). Also, high-density lipoprotein cholesterol was inversely associated with subclinical CCVA (OR 0.974; 0.965-0.982, p < 0.001). Compared with normal controls, the OR for subclinical CCVA after full adjustment was 1.46 in the mild-to-moderate NAFLD group (95% confidence interval [CI]: 1.10 to 1.93) and 2.04 in the severe NAFLD group (95% CI: 1.44 to 2.89).

CONCLUSIONS

Our data show that NAFLD is common among Korean men, and NAFLD severity on ultrasonography is associated with subclinical CCVA, as assessed by MDCT, and HR-MRA.

An Integrated Understanding of the Rapid Metabolic Benefits of a Carbohydrate-Restricted Diet on Hepatic Steatosis in Humans

A carbohydrate-restricted diet is a widely recommended intervention for non-alcoholic fatty liver disease (NAFLD), but a systematic perspective on the multiple benefits of this diet is lacking. Here, we performed a short-term intervention with an isocaloric low-carbohydrate diet with increased protein content in obese subjects with NAFLD and characterized the resulting alterations in metabolism and the gut microbiota using a multi-omics approach. We observed rapid and dramatic reductions of liver fat and other cardiometabolic risk factors paralleled by (1) marked decreases in hepatic de novo lipogenesis; (2) large increases in serum β-hydroxybutyrate concentrations, reflecting increased mitochondrial β-oxidation; and (3) rapid increases in folate-producing Streptococcus and serum folate concentrations. Liver transcriptomic analysis on biopsy samples from a second cohort revealed downregulation of the fatty acid synthesis pathway and upregulation of folate-mediated one-carbon metabolism and fatty acid oxidation pathways. Our results highlight the potential of exploring diet-microbiota interactions for treating NAFLD.

The potential role of the osteopontin-osteocalcin-osteoprotegerin triad in the pathogenesis of prediabetes in humans

AIMS

To examine the relationship between hormones involved in bone remodeling and glucose metabolism alterations in prediabetes.

METHODS

Individuals (n = 43) with NGT (BMI = 31.1 ± 1.1 kg/m²) and individuals (n = 79) with impaired glucose regulation (IGR) (BMI = 31.9 ± 1.2 kg/m²) including subjects with IFG, IGT, and IFG-IGT underwent OGTT and DXA. Osteopontin (OPN), osteocalcin (OCN), osteoprotegerin (OPG), and PTH levels were measured at fasting. Beta-cell function was calculated using C-peptide deconvolution. Dynamic indexes of insulin sensitivity were calculated from OGTT. A subgroup underwent to a euglycemic hyperinsulinemic clamp with 3-³H-glucose to estimate the endogenous glucose production (EGP) and insulin-mediated body glucose disposal (TGD/SSPI).

RESULTS

OPN was higher in IGR compared to NGT (5.3 ± 0.5 vs. 3.3 ± 0.2 μg/mL; p = 0.008) and in isolated IGT compared to IFG and IFG-IGT (6.3 ± 0.5 vs. 4.5 ± 0.3 and 5.4 ± 0.5 μg/mL; p = 0.02). OCN was similar in IFG and NGT but lower in IGT and IFG-IGT compared to NGT (7.2 ± 0.3 and 5.4 ± 0.2 vs. 8.3 ± 0.3 ng/mL; p < 0.01). OPN was positively correlated with HbA1c, fasting and 2 h plasma glucose and PTH. OCN was negatively correlated with body fat, 2 h plasma glucose, insulin and positively correlated with Stumvoll index. OPG correlated with TGD/SSPI (r = - 0.29; p < 0.05), EGP, and hepatic insulin resistance index in IGR (r = 0.51, r = 0.43; p < 0.01). There was no correlation between PTH and insulin sensitivity or Beta-cell function parameters.

CONCLUSIONS

In prediabetes, hormones known to be involved in bone remodeling may affect glucose metabolism before overt T2DM occurs with tissue-specific mechanisms.

Energy-matched moderate and high intensity exercise training improves nonalcoholic fatty liver disease risk independent of changes in body mass or abdominal adiposity - A randomized trial

BACKGROUND AND PURPOSE

Exercise training is commonly prescribed for individuals diagnosed with nonalcoholic fatty liver disease (NAFLD); however, consensus regarding the volume and intensity of exercise for optimal benefits is lacking. Thus, we determined whether high intensity interval exercise training (HIIT) produced greater reductions in intrahepatic lipid (IHL) content and NAFLD risk factors compared with energy-matched moderate intensity continuous exercise training (MICT) in obese adults with liver steatosis.

METHODS

Eighteen obese adults were randomized to either 4weeks of HIIT (4min 80% VO₂peak/3min, 50% VO₂peak) or MICT (55% VO₂peak, ~60min), matched for energy expenditure (~400kcal/session) and compared to five non-exercising age-matched control subjects. IHL was measured by ¹H-MRS and frequent blood samples were analyzed for glucose, insulin, c-peptide, and NEFA levels during a liquid meal test (180min) to characterize metabolic phenotype.

RESULTS

Baseline body weight, visceral abdominal adiposity, and fasting insulin concentrations were greater in the MICT vs HIIT group (P<0.05), while IHL was tightly matched between MICT and HIIT subjects (P>0.05), albeit higher than control subjects (P<0.01). Visceral abdominal adiposity, body mass, liver aminotransferases (ALT, AST), and hepatic apoptotic/inflammatory markers (cytokeratin 18 and fetuin a) were not reduced with either exercise training intervention (P>0.05). Both HIIT and MICT lowered IHL (HIIT, -37.0±12.4%; MICT, -20.1±6.6%, P<0.05); however, the reduction in IHL was not statistically different between exercise intensities (P=0.25). Furthermore, exercise training decreased postprandial insulin, c-peptide, and lipid peroxidation levels (iAUC, P<0.05).

CONCLUSIONS

Collectively, these findings indicate that energy-matched high intensity and moderate intensity exercise are effective at decreasing IHL and NAFLD risk that is not contingent upon reductions in abdominal adiposity or body mass.

The Common Mechanisms of Sarcopenia and NAFLD

Current studies have shown that sarcopenia and nonalcoholic fatty liver disease (NAFLD) have similar pathophysiological profiles. The cooccurrence of sarcopenia and NAFLD has been observed in elderly patients. The actions of these conditions are linked, and their treatments are similar. Therefore, studies should be conducted on NAFLD-sarcopenia rather than on NAFLD or sarcopenia.

Association between hemoglobin glycation index and hepatic steatosis in non-diabetic individuals

AIMS

Hemoglobin glycation index (HGI), which is the difference between the observed value of HbA1 and the predicted HbA1c based on plasma glucose levels, represents a measure of the degree of non-enzymatic glycation of hemoglobin and it has been found to be positively associated with diabetic complications. Herein we investigated whether HGI is associated with hepatic steatosis and related biomarkers in subjects without diabetes.

METHODS

1120 White individuals without diabetes were stratified in quartiles according to HGI levels. Hepatic steatosis was diagnosed by ultrasonography.

RESULTS

As compared with subjects in the lowest quartile of HGI those in the intermediate and high HGI groups displayed an unfavorable cardio-metabolic risk profile having significantly higher values of body mass index (BMI), waist circumference, % fat mass, total cholesterol, triglycerides, inflammatory markers such as high sensitivity C reactive protein, erythrocytes sedimentation rate, complement C3, platelets and white blood cell count, hepatic insulin resistance assessed by the liver IR index and lower concentrations of high-density lipoprotein. HGI was positively associated with the biomarker of liver damage alanine aminotransferase, and fatty liver index, an indicator of hepatic steatosis. In a logistic regression analysis adjusted for age, gender and BMI individuals in the highest quartile of HGI exhibited a 1.6-fold increased odd of having hepatic steatosis (95% CI: 1.03-2.41; p=0.03) as compared with subjects in the lowest quartile of HGI.

CONCLUSIONS

Higher levels of HGI may identify subjects without diabetes at increased risk of having hepatic steatosis.

Increased risk of cerebrovascular accident related to non-alcoholic fatty liver disease: a meta-analysis

Recent published studies on the association between non-alcoholic fatty liver disease (NAFLD) and cerebrovascular accident (CVA) risk have yielded conflicting findings. The aim of our study was to identify the potential association by pooling all available publications. A total of nine independent studies were included into our study. The pooled odd ratio (OR) with 95% confidence interval (95% CI) was calculated to weigh the strength for the relationship between NAFLD and CVA risk. We also conducted stratified analyses by study design, ethnicity and disease classification for further elucidation. The pooled results of the present meta-analysis showed that NAFLD was related to increased risk of CVA (OR = 2.32, 95% CI 1.84–2.93, P < 0.001). Besides, NAFLD is associated with increased risk of CVA among both Caucasians (OR = 2.27, 95% CI 1.77–2.90, P < 0.001) and Asians (OR = 2.81, 95% CI 1.43–5.51, P = 0.003). Moreover, the significant association was also observed in case-control studies (OR = 2.73, 95% CI 1.67–4.48, P < 0.001) and cohort studies (OR = 2.22, 95% CI 1.71–2.89, P < 0.001), respectively. In addition, NAFLD was shown to correlate with increased risk of cerebral hemorrhage (OR = 1.85, 95% CI 1.05–3.27, P = 0.034) and the ischemic stroke (OR = 2.51, 95% CI 1.92–3.28, P < 0.001). In conclusion, our findings firstly provide strong evidence for a risk effect of NAFLD on CVA development.

Association between MRI-derived hepatic fat fraction and blood pressure in participants without history of cardiovascular disease

OBJECTIVES

We assessed whether liver fat content, as determined by MRI, correlates with blood pressure (BP), a major vascular risk factor, in individuals from the general population without history of stroke and coronary or peripheral artery disease.

METHODS

Cross-sectional data from 384 participants (161 women; aged 39-73 years) of a MRI substudy of the KORA FF4 survey were used. Hepatic fat fraction (HFF) was measured in the left and right lobe of the liver using single voxel multiecho H-spectroscopy and at the level of the portal vein using a multiecho Dixon-sequence. Associations of HFF with SBP and DBP as well as hypertension were assessed by right censored normal regression (accounting for antihypertensive treatment) and by logistic regression, respectively.

RESULTS

High levels of HFF measured on the level of the portal vein (90th percentile, 21.8%), compared with low HFF levels (10th percentile, 1.7%), were associated with higher SBP (131 vs. 122 mmHg; overall P = 0.001), higher DBP (82 vs. 76 mmHg, P < 0.001) and with higher odds of hypertension [odds ratio (OR) = 2.16, P = 0.025]. A level of 5.13% (54th percentile) was identified as optimal HFF cut-off for the prediction of hypertension (OR = 2.00, P = 0.015). Alcohol consumption emerged as an effect modifier for the association between HFF and hypertension (nonalcohol drinker: OR = 3.76, P = 0.025; alcohol drinker: OR = 1.59, P = 0.165).

CONCLUSION

MRI-derived subclinical HFF is associated with SBP and DBP as well as with hypertension in participants from the general population without history of cardiovascular disease.

Fibroblast Growth Factor 21-Metabolic Role in Mice and Men

Since its identification in 2000, the interest of scientists in the hepatokine fibroblast growth factor (FGF) 21 has tremendously grown, and still remains high, due to a wealth of very robust data documenting this factor's favorable effects on glucose and lipid metabolism in mice. For more than ten years now, intense in vivo and ex vivo experimentation addressed the physiological functions of FGF21 in humans as well as its pathophysiological role and pharmacological effects in human metabolic disease. This work produced a comprehensive collection of data revealing overlaps in FGF21 expression and function but also significant differences between mice and humans that have to be considered before translation from bench to bedside can be successful. This review summarizes what is known about FGF21 in mice and humans with a special focus on this factor's role in glucose and lipid metabolism and in metabolic diseases, such as obesity and type 2 diabetes mellitus. We highlight the discrepancies between mice and humans and try to decipher their underlying reasons.

CD40 signaling and hepatic steatosis: Unanticipated links

Obesity predisposes to an increased risk of nonalcoholic fatty liver disease (NAFLD). Hepatic steatosis is the key pathological feature of NAFLD and has emerged as a metabolic disorder in which innate and adaptive arms of the immune response play a central role in disease pathogenesis. Recent studies have revealed unexpected relationships between CD40 signaling and hepatic steatosis in high fat diet rodent models. CD154, the ligand of CD40, is a mediator of inflammation and controls several critical events of innate and adaptive immune responses. In the light of these reports, we discuss potential links between CD40 signaling and hepatic steatosis in NAFLD.

Type 1 Diabetes and Non-Alcoholic Fatty Liver Disease: When Should We Be Concerned? A Nationwide Study in Brazil

Obesity is increasing worldwide, affecting even patients with type 1 diabetes (T1D). A higher prevalence of associated comorbidities is expected, such as non-alcoholic fatty liver disease (NAFLD). This paper reports a cross-sectional multicenter study on a population with T1D (n = 1662), which aimed to evaluate the prevalence of metabolic syndrome (MS), a known risk factor for NAFLD, and to investigate predisposing factors associated with MS, as well as factors associated with elevated alanine aminotransferase (ALT), as it correlates to liver fat content. Patients were from 14 public clinics of 10 cities from all geographical regions of Brazil. A high prevalence of MS was found, especially among adults (32.3%), and this was related to age, female gender, acid uric levels, and the presence of acanthosis nigricans. ALT above the normal range was associated with triglyceride levels (especially above 129.5 mg/dL), serum uric acid, age, male gender, HbA1c, and non-Caucasian ethnicity. Patients with T1D, metabolic syndrome, and the aforementioned factors may be at a higher risk of NAFLD and should be referred to ultrasound for NAFLD evaluation. Further studies are necessary to establish the prevalence of NAFLD in individuals with T1D and to determine the disease’s progression in these patients.

Additive effect of non-alcoholic fatty liver disease on the development of diabetes in individuals with metabolic syndrome

INTRODUCTION

Non-alcoholic fatty liver disease (NAFLD) is considered as the hepatic manifestation of the metabolic syndrome (MetS), with insulin resistance as the common pathophysiology. In a current longitudinal cohort study, we evaluated the separate and combined effects of MetS and NAFLD on incident diabetes risk.

METHODS

Participants were categorized into four groups on the basis of the presence of NAFLD and MetS at baseline (i.e., with NAFLD, with MetS, with both, or without either). We compared the development of diabetes among these four groups.

RESULTS

During the mean follow up of 4years, 435 of the 7849 participants (5.5%) developed diabetes. The age, sex, and smoking-adjusted risk of incident diabetes was higher in the NAFLD only group (HR 1.51, 95% CI 1.14-1.99), MetS only group (HR 2.82, 95% CI 2.01-3.95), and both group (HR 5.45, 95% CI 4.32-6.82) compared with the group of neither. When compared with the NAFLD only group, the adjusted HR for incident diabetes was 1.87 (95% CI 1.29-2.72) in the MetS only group and 3.62 (95% CI 2.74-4.77) in both group. Among individuals with MetS, the presence of NAFLD showed a significant increase in risk of incident diabetes even after further adjustment for MetS components including fasting glucose, TG, BMI, systolic BP, and HDL-C (HR 1.53, 95% CI 1.09-2.16).

CONCLUSION

The presence of NAFLD further increased the risk of incident diabetes in individuals with metabolic syndrome. Our results suggest that the coexistence of NAFLD has an additive effect on the development of diabetes in individuals with MetS.

Fatty liver as a risk factor for progression from metabolically healthy to metabolically abnormal in non-overweight individuals

PURPOSE

Recent studies identified that metabolically abnormal non-obese phenotype is a risk factor for cardiovascular diseases. However, little is known about risk factor for progression from metabolically healthy non-overweight to metabolically abnormal phenotype. We hypothesized that fatty liver had a clinical impact on progression from metabolically healthy non-overweight to metabolically abnormal phenotype.

METHODS

In this retrospective cohort study, 14,093 Japanese (7557 men and 6736 women), who received the health-checkup program from 2004 to 2012, were enrolled. Overweight and obesity were defined as body mass index 23.0-25.0 and ≥25.0 kg/m². Four metabolic factors (impaired fasting glucose, hypertension, hypertriglyceridemia and low high density lipoprotein-cholesterol concentration) were used for definition of metabolically healthy (less than two factors) or metabolically abnormal (two or more). We divided the participants into three groups: metabolically healthy non-overweight (9755 individuals, men/women = 4290/5465), metabolically healthy overweight (2547 individuals, 1800/747) and metabolically healthy obesity (1791 individuals, 1267/524). Fatty liver was diagnosed by ultrasonography.

RESULTS

Over the median follow-up period of 5.3 years, 873 metabolically healthy non-overweight, 512 metabolically healthy overweight and 536 metabolically healthy obesity individuals progressed to metabolically abnormal. The adjusted hazard risks of fatty liver on progression were 1.49 (95% confidence interval 1.20-1.83, p = 0.005) in metabolically healthy non-overweight, 1.37 (1.12-1.66, p = 0.002) in metabolically healthy overweight and 1.38 (1.15-1.66, p < 0.001) in metabolically healthy obesity, after adjusting for age, sex, alcohol, smoking, exercise, impaired fasting glucose, hypertension, hypertriglyceridemia, low high density lipoprotein-cholesterol concentration, and abdominal obesity.

CONCLUSIONS

Fatty liver is an independent risk factor for progression from metabolically healthy status to metabolically abnormal phenotype, even in non-overweight individuals.

Intrahepatic fat, abdominal adipose tissues, and metabolic state: magnetic resonance imaging study

BACKGROUND

Intrahepatic fat (IHF) is best known to associate with waist circumference (WC) and visceral adipose tissue (VAT), but its relation to abdominal subcutaneous adipose tissue is controversial. While IHF ≥ 5% dichotomously defines fatty liver, %IHF is rarely considered as a continuous variable that includes the normal range. In this study, we aimed to evaluate %IHF association with abdominal fat subdepots, pancreatic, and renal-sinus fats.

METHODS

We evaluated %IHF, abdominal fat subdepots, %pancreatic, and renal-sinus fats, among individuals with moderate abdominal obesity, using 3-Tesla magnetic resonance imaging.

RESULTS

Among 275 participants, %IHF widely ranged (0.01%-50.4%) and was lower in women (1.6%) than men (7.3%; P < .001). In an age, sex, and WC-adjusted models, VAT area (P < .006) was directly associated with %IHF, while superficial-subcutaneous adipose tissue proportion was inversely associated with %IHF (P < .006). In these models, renal-sinus fat was positively associated with %IHF (P = .005). In an age, sex, WC, and VAT-adjusted models, elevated liver enzymes, glycemic, lipid, and inflammatory biomarkers were associated with increased %IHF (P < .003 for all). In these models, the associations remained robust even within the normal range strata of IHF < 5% for triglycerides and chemerin (P ≤ .004 for all). For the diagnosis of fatty liver, the joint area under the curve of WC, alanine-aminotransferase, triglycerides/high-density lipoprotein cholesterol, and homeostasis model assessment of insulin resistance was 0.84(95% CI, 0.79-0.89).

CONCLUSIONS

Intrahepatic fat is differentially associated with abdominal fat subdepots. Intrahepatic-fat as a continuous variable could be predicted by specific traditional parameters, even within the current normal range, and partially independent of VAT.

Genetic determination of body fat distribution and the attributive influence on metabolism

OBJECTIVE

Genome-wide association studies (GWAS) have identified single-nucleotide polymorphisms (SNPs) associated with estimates of body fat distribution. Using predefined risk allele scores, the correlation of these scores with precisely quantified body fat distribution assessed by magnetic resonance (MR) imaging techniques and with metabolic traits was investigated.

METHODS

Data from 4,944 MR scans from 915 subjects of European ancestry were analyzed. Body fat distribution was determined by MR imaging and liver fat content by ¹ H-MR spectroscopy. All subjects underwent a five-point 75-g oral glucose tolerance test. A total of 65 SNPs with reported genome-wide significant associations regarding estimates of body fat distribution were genotyped. Four genetic risk scores were created by summation of risk alleles.

RESULTS

A higher allelic load of waist-to-hip ratio SNPs was associated with lower insulin sensitivity, higher postchallenge glucose levels, and more visceral and less subcutaneous fat mass.

CONCLUSIONS

GWAS-derived polymorphisms estimating body fat distribution are associated with distinct patterns of body fat distribution exactly measured by MR. Only the risk score associated with the waist-to-hip ratio in GWAS showed an unhealthy pattern of metabolism and body fat distribution. This score might be useful for predicting diseases associated with genetically determined, unhealthy obesity.

New insight into inter-organ crosstalk contributing to the pathogenesis of non-alcoholic fatty liver disease (NAFLD)

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver dysfunction and a significant global health problem with substantial rise in prevalence over the last decades. It is becoming increasingly clear that NALFD is not only predominantly a hepatic manifestation of metabolic syndrome, but also involves extra-hepatic organs and regulatory pathways. Therapeutic options are limited for the treatment of NAFLD. Accordingly, a better understanding of the pathogenesis of NAFLD is critical for gaining new insight into the regulatory network of NAFLD and for identifying new targets for the prevention and treatment of NAFLD. In this review, we emphasize on the current understanding of the inter-organ crosstalk between the liver and peripheral organs that contributing to the pathogenesis of NAFLD.

Pediatric Non-Alcoholic Fatty Liver Disease

With the increase in the prevalence of obesity, non-alcoholic fatty liver disease (NAFLD) has become among the leading causes of chronic liver disease in the pediatric age group. Once believed to be a “two-hit process”, it is now clear that the actual pathophysiology of NAFLD is complex and involves multiple pathways. Moreover, NAFLD is not always benign, and patients with non-alcoholic steatohepatitis (NASH) are at increased risk of developing advanced stages of liver disease. It has also been shown that NAFLD is not only a liver disease, but is also associated with multiple extrahepatic manifestations, including cardiovascular diseases, type 2 diabetes, and low bone mineral density. Although the data is scarce in the pediatric population, some studies have suggested that long-term mortality and the requirement of liver transplantation will continue to increase in patients with NAFLD. More studies are needed to better understand the natural history of NAFLD, especially in the pediatric age group.

Hepatic FDG uptake is associated with future cardiovascular events in asymptomatic individuals with non-alcoholic fatty liver disease

BACKGROUND

Hepatic F-18 fluoro-2-deoxyglucose (FDG) uptake is associated with non-alcoholic fatty liver disease (NAFLD) which is an independent risk factor for cardiovascular disease. However, the value of hepatic FDG uptake for predicting future cardiovascular events has not been explored.

METHODS AND RESULTS

Study participants were 815 consecutive asymptomatic participants who underwent a health screening program that included FDG positron emission tomography/computed tomography (PET/CT), abdominal ultrasonography, and carotid intima-media thickness (CIMT) measurements (age 51.8 ± 6.0 year; males 93.9%). We measured hepatic FDG uptake and assessed the prognostic significance of this parameter with other cardiovascular risk factors including Framingham risk score and CIMT. Multivariate Cox proportional hazards analyses including all study participants revealed that NAFLD with high-hepatic FDG uptake was the only independent predictor for future cardiovascular events [hazard ratio (HR) 4.23; 95% CI 1.05-17.04; P = .043). Subgroup analysis conducted in the NAFLD group showed that high-hepatic FDG uptake was a significant independent predictor of cardiovascular events (HR 9.29; 95% CI 1.05-81.04; P = .045).

CONCLUSIONS

This exploratory study suggests that high-hepatic FDG uptake may be a useful prognostic factor for cardiovascular events in individuals with NAFLD.

Association of calf circumference with insulin resistance and non-alcohol fatty liver disease: the REACTION study

BACKGROUND

The feature of nonalcoholic fatty liver disease (NAFLD) is pathological excessive liver lipid accumulation of subjects who without history of alcohol abuse. Calf circumference is a proxy for lower-body fat and screening method for the identification of subjects with acatastatic lipid accumulation. The objective of this study was to examine the association between calf circumference and NAFLD.

METHODS

The study was a cross-sectional analysis including 8850 middle-aged and elderly individuals. NAFLD was examined by hepatic ultrasound and without alcohol abuse and other liver diseases. Calf circumference was measured on the lower right leg at the point of maximal circumference.

RESULTS

The mean of calf circumference were 35.7 cm for male and 34.6 cm for female (P < 0.001), respectively. Compared with the lowest calf circumference quartile, the odds ratio for NAFLD in the highest quartile was 2.73 (95% CI 2.34-3.19, P _trend <0.001) after adjusted for potential cofounders. There were also significant positive correlation between calf circumference and HOMA-IR, liver enzyme levels and triglycerides. In addition, we found significant positive correlation of calf circumference with the HOMA-IR and fasting insulin level in overweight and obese subjects (BMI ≥ 24 kg/m2) but not in lean subjects (test for interaction: P both less than 0.001 for insulin and HOMA-IR).

CONCLUSION

High calf circumference is significantly associated with elevated prevalence of NAFLD and increasing insulin resistance.

Nonoverweight nonalcoholic fatty liver disease and incident cardiovascular disease: A post hoc analysis of a cohort study

Nonalcoholic fatty liver disease (NAFLD) is known as a risk of incident cardiovascular disease (CVD). About 20% of NAFLD occurs in nonobese individuals. However, it remains to be elucidated the association between nonoverweight with NAFLD and a risk of incident CVD. Therefore, we investigated the risk of nonoverweight with NAFLD for incident CVD.We performed a post-hoc analysis of the previous prospective cohort study, in which 1647 Japanese were enrolled. Abdominal ultrasonography was used to diagnose NAFLD. Overweight was defined as body mass index ≥23 kg/m, which is recommended by World Health Organization for Asian. We divided participants into 4 phenotypes by existence of NAFLD and/or overweight. The hazard risks of the 4 phenotypes for incident CVD were calculated by Cox hazard model after adjusting for age, sex, smoking status, exercise, hypertension, hyperglycemia, hypertriglyceridemia, and low high-density lipoprotein cholesterol at baseline examination.Incident proportions of CVD were 0.6% in nonoverweight without NAFLD, 8.8% in nonoverweight with NAFLD, 1.8% in overweight without NAFLD, and 3.3% in overweight with NAFLD. Compared with nonoverweight without NAFLD, the adjusted hazard ratios of incident CVD were 10.4 (95% confidence interval 2.61-44.0, P = .001) in nonoverweight with NAFLD, 1.96 (0.54-7.88, P = .31) in overweight without NAFLD, and 3.14 (0.84-13.2, P = .09) in overweight with NAFLD.Nonoverweight with NAFLD was associated with higher risk of incident CVD. We should pay attention to NAFLD, even in nonoverweight individuals, to prevent further CVD events.

Metabolic Syndrome as a Multifaceted Risk Factor for Oxidative Stress

SIGNIFICANCE

Metabolic syndrome (MetS) is associated with a greater risk of diabetes and cardiovascular diseases. It is estimated that this multifactorial condition affects 20%-30% of the world's population. A detailed understanding of MetS mechanisms is crucial for the development of effective prevention strategies and adequate intervention tools that could curb its increasing prevalence and limit its comorbidities, particularly in younger age groups. With advances in basic redox biology, oxidative stress (OxS) involvement in the complex pathophysiology of MetS has become widely accepted. Nevertheless, its clear association with and causative effects on MetS require further elucidation. Recent Advances: Although a better understanding of the causes, risks, and effects of MetS is essential, studies suggest that oxidant/antioxidant imbalance is a key contributor to this condition. OxS is now understood to be a major underlying mechanism for mitochondrial dysfunction, ectopic lipid accumulation, and gut microbiota impairment.

CRITICAL ISSUES

Further studies, particularly in the field of translational research, are clearly required to understand and control the production of reactive oxygen species (ROS) levels, especially in the mitochondria, since the various therapeutic trials conducted to date have not targeted this major ROS-generating system, aimed to delay MetS onset, or prevent its progression.

FUTURE DIRECTIONS

Multiple relevant markers need to be identified to clarify the role of ROS in the etiology of MetS. Future clinical trials should provide important proof of concept for the effectiveness of antioxidants as useful therapeutic approaches to simultaneously counteract mitochondrial OxS, alleviate MetS symptoms, and prevent complications. Antioxid. Redox Signal. 26, 445-461.

[Features of a necrotic and inflammatory process in different forms of nonalcoholic fatty liver disease]

AIM

To identify the features of development of a necrotic and inflammatory process in different forms of nonalcoholic fatty liver disease (NAFLD), by comparatively analyzing a full set of clinical and laboratory parameters, including the cytokine status and the expression level of enzyme genes controlling the apoptosis of peripheral leukocytes.

SUBJECTS AND METHODS

86 patients with NAFLD, including 8 (9.3%) with hepatic steatosis (HS), 70 (81.4%) with nonalcoholic steatohepatitis (NASH), 40, 19, and 11 with mild, moderate, and high disease activity, respectively, and 8 (9.3%) with liver cirrhosis (LC), were examined. A control group consisted of 34 healthy donors. Clinical and biochemical blood indices, cytokine profile, and the level of caspase gene transcripts in the peripheral blood leukocytes (PBL) were estimated.

RESULTS

As compared to the controls, the patients with HS had higher tumor necrosis factor-α (TNF-α) and interleukin 6 (IL-6) levels and lower caspase 3, 6, and 8 mRNA in PBL. The concentration of IL-10 in NASH was higher than that in steatosis and positively correlated with the level of proinflammatory cytokines. The levels of TNF-α and IL6 were higher in the patients with NASH than in the controls. Those of C-reactive protein, γ-globulin, IL-6, and cytokeratin-18 fragment increased with the progression of NASH. In the latter, the transcriptional activity of caspase-3 gene decreased relative to the reference value and negatively correlated with the level of proinflammatory cytokines. In the patients with LC, the gene expression profile of caspases in PBL was similar to that in the control group; the level of IL-6 was higher than that in steatosis and NASH, that of IL-1β was higher than in HS and positively correlated the concentration of IL-6 and the activity of alanine aminotransferase and aspartate aminotransferase.

CONCLUSION

The features of a necrotic and inflammatory process were identified in different forms of NAFLD. When the latter progressed, the cytokine profile and gene expression levels of caspases in PBL altered along with a change in the general clinical picture.