Hypoadiponectinemia plays a crucial role in the development of nonalcoholic fatty liver disease in patients with type 2 diabetes mellitus independent of visceral adipose tissue

Correlation Between Clinical Features of Type 2 Diabetes Mellitus with CT Findings of Fatty Liver Patients

People with fatty liver disease are at major risk of liver cirrhosis and malignancies. This study aims to evaluate the correlation between fatty liver and diabetes features on computed tomography (CT) using Hounsfield units for the liver and spleen. The research was conducted in Jeddah Hospital’s Medical Imaging Department and CT scan department from March 2018 until March 2020. A total of 50 patients with diabetes were chosen randomly, with males (26) and females (24) ranging in age from 31 to 80 years old. Descriptive statistics of body mass index were recorded for the liver and the spleen; the main liver enzymes were Alanine aminotransferase (ALT), Gamma-glutamyltransferase (GGT), albumin, total bilirubin, and direct bilirubin, which were measured and analyzed using the Statistical Package for the Social Sciences program, version 23. We found a significant correlation of ALT and direct bilirubin with liver and spleen HU at p value < 0.017 and < 0.073, respectively; the mean and standard deviation for the other liver enzymes GGT, albumin, and total bilirubin in segment 3 of the left liver were 45.48 ± 7.077 HU, 45.00 ± 7.797 HU, 36.67 ± 5.776 HU, and 37.23 ± 4.885 HU, respectively. We concluded that fatty liver is associated with type 2 diabetes mellitus symptoms such as high ALT and direct bilirubin, with no significant association between GGT, albumin, total bilirubin, and liver and spleen HU.

Low level of adiponectin predicts the development of Nonalcoholic fatty liver disease: is it irrespective to visceral adiposity index, visceral adipose tissue thickness and other obesity indices?

We aimed to study the correlation of adiponectin level with insulin resistance (IR), carotid intima-media thickness (cIMT), and various obesity indices especially visceral adipose tissue (VAT) thickness, and visceral adiposity index (VAI), in patients with NAFLD (n = 41), T2D (n = 22), NAFLD + T2D (n = 41), and healthy subjects (n = 20). Results showed the median level of adiponectin in patients with NAFLD (2.97 μg/mL) and ones with NAFLD + T2D (3.21 μg/mL) is significantly lower rather than in controls (4.39 μg/mL). Moreover, VAI is the only predictor for adiponectin concentration in the combination of patient groups and also in all participants independent of IR and other obesity indices. Adiponectin level had also a positive correlation with cIMT and IR in NAFLD patients. Interestingly, lower level of adiponectin was associated with the presence of T2D, NAFLD, and NAFLD + T2D independent of IR and obesity indices. Collectively, it seems that VAI reflecting visceral adipose tissue function is a possible predictor of adiponectin level.

Determination of “indeterminate score” measurements in lean nonalcoholic fatty liver disease patients from western Saudi Arabia

BACKGROUND

Noninvasive measures to estimate liver fibrosis in lieu of biopsy in nonalcoholic liver disease (NAFLD) can broadly differentiate high vs low degrees of condition extent. However, an “indeterminate score” necessitates further clinical investigation and biopsy becomes essential, highlighting the need for identification of other noninvasive factors with accuracy for this midlevel extent and its prognosis. Lean NAFLD cases are of particular interest regarding this issue, as they present as otherwise healthy, and will benefit greatly from the less invasive assessment.

AIM

To estimate the agreement of two noninvasive assessment tools in lean NAFLD patients, and assess factors related to indeterminate scores.

METHODS

Ultrasound-diagnosed NAFLD patients, without sign of other chronic liver disease (n = 1262), were enrolled from a tertiary private medical centre between 2016-2019. After grouping by body mass index (obese, overweight, and lean), each participant underwent FibroScan. NAFLD fibrosis score (NFS) was used for subclassification (lower, higher, and indeterminate). No patient underwent liver biopsy. The kappa statistic was used to assess inter-rater agreement between the three groups on liver fibrosis degree assessed via FibroScan and NFS. Indeterminate score among the three groups was assessed to identify factors that predict its determination.

RESULTS

The NAFLD study cohort was composed of lean (159/1262, 12.6%), overweight (365/1262, 29%) and obese (737/1262, 58.4%) individuals. The lean patients were significantly younger (49.95 ± 15.3 years, P < 0.05), with higher serum high density lipoprotein (52.56 ± 16.27 mg/dL, P < 0.001) and lower prevalences of type 2 diabetes mellitus, hypertension and hyperlipidaemia. All groups showed a predominance of lower fibrosis degree. The lean NAFLD patients showed a significantly lower NFS (P < 0.001). Degree of agreement between FibroScan and NFS was fair between the lean and obese NAFLD categories, and moderate in the overweight category. NFS was predictive of indeterminate score. Age was a factor among all the body mass index (BMI) categories; other associated factors, but with less strength, were serum alanine aminotransferase in the overweight category and BMI in the obese category.

CONCLUSION

Lean NAFLD patients showed lower degree and prevalence of liver fibrosis by NFS; however, follow-up biopsy is still needed.

Activation of heat shock response improves biomarkers of NAFLD in patients with metabolic diseases

Nonalcoholic fatty liver disease (NAFLD) is often accompanied by metabolic disorders such as metabolic syndrome and type 2 diabetes (T2DM). Heat shock response (HSR) is one of the most important homeostatic abilities but is deteriorated by chronic metabolic insults. Heat shock (HS) with an appropriate mild electrical stimulation (MES) activates HSR and improves metabolic abnormalities including insulin resistance, hyperglycemia and inflammation in metabolic disorders. To analyze the effects of HS + MES treatment on NAFLD biomarkers, three cohorts including healthy men (two times/week, n = 10), patients with metabolic syndrome (four times/week, n = 40), and patients with T2DM (n = 100; four times/week (n = 40) and two, four, seven times/week (n = 20 each)) treated with HS + MES were retrospectively analyzed. The healthy subjects showed no significant alterations in NAFLD biomarkers after the treatment. In patients with metabolic syndrome, many of the NAFLD steatosis markers, including fatty liver index, NAFLD-liver fat score, liver/spleen ratio and hepatic steatosis index and NAFLD fibrosis marker, aspartate aminotransferase/alanine aminotransferase (AST/ALT) ratio, were improved upon the treatment. In patients with T2DM, all investigated NAFLD steatosis markers were improved and NAFLD fibrosis markers such as the AST/ALT ratio, fibrosis-4 index and NAFLD-fibrosis score were improved upon the treatment. Thus, HS + MES, a physical intervention, may become a novel treatment strategy for NAFLD as well as metabolic disorders.

Adiponectin as a novel biomarker for liver fibrosis

Adiponectin is known to play primary roles in the regulation of systemic glucose homeostasis and lipid metabolism. Interestingly, emerging evidence indicates beneficial effects of adiponectin on liver fibrosis; however, the exact mechanisms of this action remain unclear. Herein, we aimed to summarize the recent findings regarding the role of adiponectin in liver fibrogenesis and update the current comprehensive knowledge regarding usefulness of adiponectin-based treatments in liver fibrosis. Adiponectin has been demonstrated to have an anti-fibrotic action in the liver by blocking the activation of hepatic stellate cell-mediated adenosine monophosphate-activated protein kinase and peroxisome proliferator-activated receptor-alpha pathways, which in turn diminish the expression of pro-fibrotic genes. In addition, hyperadiponectinemia was noted in patients with various chronic liver diseases (CLDs)-related liver fibrosis. An increase in circulating adiponectin levels was also found to be associated with the development of liver fibrosis, indicating a role of adiponectin as a non-invasive biomarker for predicting the progression of liver fibrosis. It is therefore reasonable to speculate that adiponectin may be developed as a new therapeutic candidate for the treatment of liver fibrosis. Nonetheless, future observations are still necessary to fully elucidate the extent of the effects of adiponectin on liver fibrotic outcomes, in order to modify adiponectin as an anti-fibrotic therapy that would speed up fibrosis reversal in patients with CLD.

Clinical characteristics of patients with diabetes mellitus and fatty liver diagnosed by liver/spleen Hounsfield units on CT scan

Objective The leading cause of liver injuries in diabetes mellitus may be associated with fatty liver. We aimed to elucidate the relationship between fatty liver and diabetes characteristics. Methods Retrospectively, 970 patients with diabetes were analysed. Fatty liver was diagnosed when the liver/spleen Hounsfield unit ratio by computed tomography was below 0.9. Clinical diabetes characteristics were compared between patients with and without fatty liver. Results Of 970 patients (717 male and 253 female; mean age 64.4 years), 175 males (24.4%) and 60 females (23.7%) had fatty liver. None of the 28 patients with type 1 diabetes had fatty liver. In male patients with type 2 diabetes, age, visceral adipose tissue (VAT), albumin, alanine amino-transferase (ALT), and triglycerides were independently associated with fatty liver. In females, age and bilirubin were associated with fatty liver. Conclusions Fatty liver is associated with type 2 diabetes characteristics, including younger age and elevated VAT, albumin, ALT, and triglycerides in males and younger age and elevated bilirubin levels in females.

Expansion of Bone Marrow Adipose Tissue During Caloric Restriction Is Associated With Increased Circulating Glucocorticoids and Not With Hypoleptinemia

Bone marrow adipose tissue (MAT) accounts for up to 70% of bone marrow volume in healthy adults and increases further in clinical conditions of altered skeletal or metabolic function. Perhaps most strikingly, and in stark contrast to white adipose tissue, MAT has been found to increase during caloric restriction (CR) in humans and many other species. Hypoleptinemia may drive MAT expansion during CR but this has not been demonstrated conclusively. Indeed, MAT formation and function are poorly understood; hence, the physiological and pathological roles of MAT remain elusive. We recently revealed that MAT contributes to hyperadiponectinemia and systemic adaptations to CR. To further these observations, we have now performed CR studies in rabbits to determine whether CR affects adiponectin production by MAT. Moderate or extensive CR decreased bone mass, white adipose tissue mass, and circulating leptin but, surprisingly, did not cause hyperadiponectinemia or MAT expansion. Although this unexpected finding limited our subsequent MAT characterization, it demonstrates that during CR, bone loss can occur independently of MAT expansion; increased MAT may be required for hyperadiponectinemia; and hypoleptinemia is not sufficient for MAT expansion. We further investigated this relationship in mice. In females, CR increased MAT without decreasing circulating leptin, suggesting that hypoleptinemia is also not necessary for MAT expansion. Finally, circulating glucocorticoids increased during CR in mice but not rabbits, suggesting that glucocorticoids might drive MAT expansion during CR. These observations provide insights into the causes and consequences of CR-associated MAT expansion, knowledge with potential relevance to health and disease.

Association of adiponectin gene variation with progression of nonalcoholic fatty liver disease: A 4-year follow-up survey

OBJECTIVE

To explore the role of tagging single nucleotide polymorphisms (tagSNPs) in the adiponectin gene in the natural course of nonalcoholic fatty liver disease (NAFLD).

METHODS

The participants were chosen from our previous survey containing 3543 individuals. Finally, a total of 696 participants who had been followed up for a median of 4 years were included. Each participant was administered with an interview, physical examination, blood tests and ultrasonic examination at both baseline and end-point. Polymerase chain reaction-restriction fragment length polymorphism was applied to determine seven tagSNPs in the adiponectin gene, namely, rs182052, rs16861205, rs822396, rs7627128, rs1501299, rs2241767 and rs3774261. Ordinal logistic regression was used to screen risk factors of NAFLD progression as well as the susceptibility to the disease. Haplotypes analyses were performed to confirm the results.

RESULTS

After adjusting for age and gender, rs1501299 (G276T), rs2241767 (A45G) and rs3774261 (A712G) were found to be risk factors of both susceptibility (OR 5.040, 7.471 and 3.546, respectively) and progression (OR 3.83, 3.51 and 3.30, respectively) to NAFLD. Nevertheless, rs182052, rs16861205, rs822396 and rs7627128 had no impact on them. These findings were confirmed by haplotype analysis.

CONCLUSION

The tagSNPs rs2241767, rs1501299 and rs3774261 in the adiponectin gene are risk factors for the individuals' susceptibility to and progression of NAFLD.

Adiponectin as an anti-fibrotic and anti-inflammatory adipokine in the liver

Hepatic fibrosis is a dynamic process resulting from excessive deposition of extracellular matrix in the liver; uncontrolled progression of fibrosis can eventually lead to liver cirrhosis and/or hepatocellular carcinoma. The fibrogenic process is complex and modulated by a number of both hepatic and extra-hepatic biological factors. Growing evidence indicates that adipokines, a group of cytokines produced by adipose tissue, impart dynamic functions in liver and are involved in modulation of hepatic fibrosis. In particular, two key adipokines, adiponectin and leptin, directly regulate many biological responses closely associated with development and progression of hepatic fibrosis. Leptin acts as a pro-fibrogenic cytokine, while adiponectin possesses anti-fibrogenic and anti-inflammatory properties. Adiponectin, acting via its cognate receptors, adiponectin receptors 1 and 2, potently suppresses fibrosis and inflammation in liver via multiple mechanisms. This review summarizes recent findings concerning the role of adiponectin in fibrogenic process in liver and addresses the underlying molecular mechanisms in modulation of fibrosis.

Impact of glucose tolerance on the severity of non-alcoholic steatohepatitis

Aims/Introduction:  We investigated the relationship between non‐alcoholic steatohepatitis (NASH) and different stages of fasting plasma glucose (FPG) concentrations, and the association between factors related to glucose tolerance and severity of NASH.

Materials and Methods:  A total of 147 patients with non‐alcoholic fatty liver disease (NAFLD) who had undergone a liver biopsy were divided into three groups: a normal glucose tolerance (NGT) group, an impaired fasting glucose (IFG) group and a diabetes (DM) group. In addition, to investigate progression factors of NASH in the DM group, we divided the diabetic patients into two groups: a group with NASH (NASH group) and a group without NASH, the simple steatosis (SS) group. The relationship between the patients’ clinical parameters and the severity of NAFLD/NASH were analyzed.

Results:  In the patients with liver biopsies, the IFG group had the highest percentage of NASH. There was no correlation between FPG and either total NAFLD activity scores (NAS) or staging of NASH, but the fasting serum insulin was correlated significantly with both, even after adjusting for age, sex and body mass index. Among the diabetic patients, the fasting insulin values in the NASH group were significantly higher than in the SS group, but there were no differences in FPG or A1c values between the two groups. The fasting serum insulin correlated significantly with total NAS, but the FPG and A1c values did not.

Conclusions:  A high percentage of the IFG group developed NASH. Hyperinsulinemia, but not hyperglycemia, was associated with severity of NASH. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2011.00134.x, 2011)

The prevalence and predictors of active brown adipose tissue in Chinese adults

OBJECTIVE

Previous studies have shown that active brown adipose tissue (BAT) is present in adults and may play important roles in the regulation of energy homeostasis. However, nearly every study has been carried out in patients undergoing scanning for cancer surveillance (CS), whose metabolism and BAT activity may not reflect those of healthy individuals. The objective of this study was to investigate the prevalence and predictors of active BAT in Chinese adults, particularly in healthy individuals.

DESIGN

A total of 31,088 consecutive subjects aged ≥18 years who had undergone positron emission tomography/computed tomography (PET/CT) scanning of BAT were evaluated in this study.

METHODS

We measured BAT activity via (18)F-fluorodeoxyglucose PET/CT in subjects who had undergone scanning for either a routine medical checkup (MC) or CS in Shanghai. Then, we investigated the predictors of active BAT, particularly in healthy individuals.

RESULTS

In both groups, the prevalence of BAT was higher in women than in men. Using a multivariate logistic analysis, we found age, sex, BMI, and high thyroid glucose uptake to be significant predictors of BAT activity in the MC group. Similarly, we found age, sex, and BMI to be significant predictors of BAT activity, but not thyroid high glucose uptake, in the CS group.

CONCLUSIONS

In Chinese adults, BAT activity inversely correlates with BMI and thyroid high glucose uptake, which reinforces the central role of brown fat in adult metabolism and provides clues to a potential means for treating the metabolic syndrome.

Liver fat content is linked to inflammatory changes in subcutaneous adipose tissue in type 2 diabetes patients

BACKGROUND

Patients with type 2 diabetes mellitus (T2DM) are typically overweight and have an increased liver fat content (LFAT). High LFAT may be explained by an increased efflux of free fatty acids from the adipose tissue, which is partly instigated by inflammatory changes. This would imply an association between inflammatory features of the adipose tissue and liver fat content.

OBJECTIVE

To analyse associations between inflammatory features of the adipose tissue and liver fat content.

DESIGN

A cross-sectional study.

PATIENTS

Twenty-seven obese patients with insulin-treated T2DM were studied.

MEASUREMENTS

LFAT content was measured by proton magnetic resonance spectroscopy. A subcutaneous (sc) fat biopsy was obtained to determine morphology and protein levels within adipose tissue. In addition to fat cell size, the percentage of macrophages and the presence of crown-like structures (CLSs) within sc fat were assessed by CD68-immunohistochemical staining.

RESULTS

Mean LFAT percentage was 11·1 ± 1·7% (range: 0·75-32·9%); 63% of the patients were diagnosed with an elevated LFAT (upper range of normal ≤5·5%). Whereas adipocyte size did not correlate with LFAT, 3 of 4 subjects with CLSs in sc fat had elevated LFAT and the percentage of macrophages present in sc adipose tissue was positively associated with LFAT. Protein concentrations of adiponectin within adipose tissue negatively correlated with LFAT. Adipose tissue protein levels of the key inflammatory adipokine plasminogen activator inhibitor-1 (PAI-1) were positively associated with LFAT.

CONCLUSIONS

Several pro-inflammatory changes in sc adipose tissue associate with increased LFAT content in obese insulin-treated patients with T2DM. These findings suggest that inflammatory changes at the level of the adipose tissue may drive liver fat accumulation.

Association of Adiponectin rs1501299 and rs266729 Gene Polymorphisms With Nonalcoholic Fatty Liver Disease

BACKGROUND

Genetic and environmental factors are important for the development of nonalcoholic fatty liver disease (NAFLD). Adiponectin is a white and brown adipose tissue hormone, and have been found to play essential roles in the regulation of energy homoeostasis. Recent reports have identified a possible role of adiponectin in NAFLD via PPARγ pathway.

OBJECTIVES

The present study was designed to find out the impact of adiponectin rs1501299 (276G/T) and rs266729 (-11377C/G) gene polymorphisms in NAFLD.

PATIENTS AND METHODS

Eighty-three patients with diagnosis of NAFLD, and 93 healthy subjects were included in the study. Tetra ARMS-PCR was designed to detect single nucleotide polymorphisms.

RESULTS

A significant difference was found between NAFLD and control group regarding the rs266729 polymorphism (χ2 = 7.35, P = 0.025). The rs266729 polymorphism increased the risk of NAFLD in codominant (CC vs. CG: OR = 2.18, 95% CI = 1.16 - 4.12, P = 0.016) and dominant (CC vs. CG/GG: OR = 2.31, 95% CI = 1.25 - 4.27; P = 0.008) inheritance tested models. The G allele increased the risk of NAFLD (OR = 1.63, 95% CI = 1.03 - 2.57, P = 0.037) in comparison with C allele. No significant difference was found between the groups concerning adiponectin rs1501299 gene polymorphism (χ2 = 0.70, P = 0.697).

CONCLUSIONS

adiponectin rs266729 polymorphism might be a candidate gene, which determines the susceptibility to NAFLD. Larger studies are necessary to confirm these findings in various populations.

Upregulation of UCP2 by adiponectin: the involvement of mitochondrial superoxide and hnRNP K

BACKGROUND

The adipocyte-derived hormone adiponectin elicits protective functions against fatty liver diseases and hepatic injuries at least in part by stimulating the expression of a mitochondrial inner membrane transporter, uncoupling protein 2 (UCP2). The present study was designed to investigate the cellular and molecular mechanisms underlying adiponectin-induced UCP2 expression.

METHODOLOGY/PRINCIPAL FINDINGS

Mice were treated with adiponectin and/or different drug inhibitors. Parenchymal (PCs) and nonparenchymal (NPCs) cells were fractionated from the liver tissues for mitochondria isolation, Western blotting and quantitative PCR analysis. Mitochondrial superoxide production was monitored by MitoSOX staining and flow cytometry analysis. Compared to control mice, the expression of UCP2 was significantly lower in NPCs, but not PCs of adiponectin knockout mice (AKO). Both chronic and acute treatment with adiponectin selectively increased the mRNA and protein abundance of UCP2 in NPCs, especially in the enriched endothelial cell fractions. The transcription inhibitor actinomycin D could not block adiponectin-induced UCP2 expression, whereas the protein synthesis inhibitor cycloheximide inhibited the elevation of UCP2 protein but not its mRNA levels. Mitochondrial content of heterogeneous nuclear ribonucleoprotein K (hnRNP K), a nucleic acid binding protein involved in regulating mRNA transportation and stabilization, was significantly enhanced by adiponectin, which also evoked a transient elevation of mitochondrial superoxide. Rotenone, an inhibitor of mitochondrial respiratory complex I, abolished adiponectin-induced superoxide production, hnRNP K recruitment and UCP2 expression.

CONCLUSIONS/SIGNIFICANCE

Mitochondrial superoxide production stimulated by adiponectin serves as a trigger to initiate the translocation of hnRNP K, which in turn promotes UCP2 expressions in liver.

Enhanced fatty acid flux triggered by adiponectin overexpression

Adiponectin overexpression in mice increases insulin sensitivity independent of adiposity. Here, we combined stable isotope infusion and in vivo measurements of lipid flux with transcriptomic analysis to characterize fatty acid metabolism in transgenic mice that overexpress adiponectin via the aP2-promoter (ADNTg). Compared with controls, fasted ADNTg mice demonstrated a 31% reduction in plasma free fatty acid concentrations (P = 0.008), a doubling of ketones (P = 0.028), and a 68% increase in free fatty acid turnover in plasma (15.1 ± 1.5 vs. 25.3 ± 6.8 mg/kg · min, P = 0.011). ADNTg mice had 2-fold more brown adipose tissue mass, and triglyceride synthesis and turnover were 5-fold greater in this organ (P = 0.046). Epididymal white adipose tissue was slightly reduced, possibly due to the approximately 1.5-fold increase in the expression of genes involved in oxidation (peroxisome proliferator-activated receptor α, peroxisome proliferator-activated receptor-γ coactivator 1α, and uncoupling protein 3). In ADNTg liver, lipogenic gene expression was reduced, but there was an unexpected increase in the expression of retinoid pathway genes (hepatic retinol binding protein 1 and retinoic acid receptor beta and adipose Cyp26A1) and liver retinyl ester content (64% higher, P < 0.02). Combined, these data support a physiological link between adiponectin signaling and increased efficiency of triglyceride synthesis and hydrolysis, a process that can be controlled by retinoids. Interactions between adiponectin and retinoids may underlie adiponectin's effects on intermediary metabolism.

Adiponectin regulation of stellate cell activation via PPARγ-dependent and -independent mechanisms

In this study, we elucidated the mechanism by which adiponectin modulates hepatic stellate cell activation and fibrogenesis. Adiponectin-overexpressing transgenic mice receiving thioacetamide were resistant to fibrosis, compared with controls. In contrast, adiponectin-null animals developed severe fibrosis. Expression of collagen α1(I) and α-smooth muscle actin (α-SMA) mRNAs were significantly lower in adiponectin-overexpressing mice, compared with controls. In wild-type stellate cells exposed to a lentivirus encoding adiponectin, expression of peroxisome proliferator-activated receptor-γ (PPARγ), SREBP1c, and CEBPα mRNAs was significantly increased (3.2-, 4.1-, and 2.2-fold, respectively; n = 3; P < 0.05, adiponectin virus versus control), consistent with possible activation of an adipogenic transcriptional program. Troglitazone, a PPARγ agonist, strongly suppressed up-regulation of collagen α1(I) and α-SMA mRNA in stellate cells isolated from wild-type mice; however, stellate cells from adiponectin-null animals failed to respond to troglitazone. Furthermore, in isolated stellate cells in which PPARγ was depleted using an adenovirus-Cre-recombinase system and in which adiponectin was also overexpressed, collagen α1(I) and α-SMA were significantly inhibited. We conclude that the PPARγ effect on stellate cell activation and the fibrogenic cascade appears to be adiponectin-dependent; however, the inhibitory effect of adiponectin on stellate cell activation was not dependent on PPARγ, suggesting the presence of PPARγ-dependent as well as independent pathways in stellate cells.

Prevalence of non-alcoholic fatty liver disease and its relation to hypoadiponectinaemia in the middle-aged and elderly Chinese population

INTRODUCTION

Hypoadiponectinaemia is an important risk factor for non-alcoholic fatty liver disease (NAFLD). However, little is known about its role in the Chinese population. This study sought to assess the prevalence of NAFLD and its association with hypoadiponectinaemia in middle-aged and elderly Chinese.

MATERIAL AND METHODS

We conducted a population-based cross-sectional study in an urban Shanghai sample of 2201 participants age 50 years to 83 years (973 men, 1228 women). Hepatic ultrasonographic examination was performed for all participants. Serum adiponectin concentrations were measured by ELISA methods.

RESULTS

The prevalence of NAFLD was 19.8% (16.0% in men, 22.8% in women). Serum adiponectin levels were significantly higher in female than in male subjects (p < 0.001). Serum adiponectin levels were significantly lower in NAFLD subjects than those in control subjects (p < 0.001). The prevalence of NAFLD progressively increased with declining adiponectin levels (p(for trend) < 0.001). The participants in the lowest adiponectin quartile had a significantly increased risk for acquiring NAFLD (OR = 2.31, 95% CI 1.72-3.15) after adjustment for potential confounders.

CONCLUSIONS

Population-based screening suggests that NAFLD is highly prevalent in middle-aged and elderly people in Shanghai, particularly among women. Serum adiponectin level is negatively associated with NAFLD independently of potential cofounders, indicating that hypoadiponectinaemia may contribute to the development of NAFLD.

Molecular evolution of adiponectin in Carnivora and its mRNA expression in relation to hepatic lipidosis

Adiponectin is a novel adipocyte-derived hormone with low circulating concentrations and/or mRNA expression in obesity and non-alcoholic fatty liver disease (NAFLD). The adiponectin mRNA of several Carnivora species was sequenced to enable further gene expression studies in this clade with potential experimental species to examine the connections of hypoadiponectinemia to hepatic lipidosis. In addition, adiponectin mRNA expression was studied in the retroperitoneal fat of the American mink (Neovison vison), as hepatic lipidosis with close similarities to NAFLD can be rapidly induced to the species by fasting. The mRNA expression was determined after overnight-7d of food deprivation and 28d of re-feeding and correlated to the liver fat %. The homologies between the determined carnivoran mRNA sequences and that of the domestic dog were 92.2-99.1%. As the mRNA expression was not affected by short-term fasting and did not correlate with the liver fat %, there seems to be no clear connection between adiponectin and the development of lipidosis in the American mink. In the future, the obtained sequences can be utilized in further studies of adiponectin expression in comparative endocrinology.

Preliminary report: hepatic fat and inflammation in type 2 diabetes mellitus

Although the association between inflammation and hepatic fat is fairly established, it remains unclear whether this association is independent of general measures of obesity and standard cardiovascular risk factors. Therefore, the aim of this study was to investigate the contribution of hepatic steatosis as an independent predictor of chronic inflammation in 281 subjects with type 2 diabetes mellitus. Reduced hepatic steatosis significantly (P < .01) correlated with C-reactive protein (r = -0.16) and adiponectin (r = 0.23). The association of hepatic steatosis with both C-reactive protein and adiponectin remained significant after adjustment for age, ethnicity, body mass index (or waist circumference), triglycerides, high-density lipoprotein, and total cholesterol. These data support the concept that accumulation of hepatic fat is related to enhanced inflammation in type 2 diabetes mellitus independent of general measures of obesity and standard cardiovascular risk factors.

Diabetes of the liver: the link between nonalcoholic fatty liver disease and HFCS-55

Nonalcoholic fatty liver disease (NAFLD) is associated with obesity and insulin resistance. It is also a predisposing factor for type 2 diabetes. Dietary factors are believed to contribute to all three diseases. NAFLD is characterized by increased intrahepatic fat and mitochondrial dysfunction, and its etiology may be attributed to excessive fructose intake. Consumption of high fructose corn syrup-55 (HFCS-55) stands at up to 15% of the average total daily energy intake in the United States, and is linked to weight gain and obesity. The aim of this study was to establish whether HFCS-55 could contribute to the pathogenesis of NAFLD, by examining the effects of HFCS-55 on hepatocyte lipogenesis, insulin signaling, and cellular function, in vitro and in vivo. Exposure of hepatocytes to HFCS-55 caused a significant increase in hepatocellular triglyceride (TG) and lipogenic proteins. Basal production of reactive oxygen metabolite (ROM) was increased, together with a decreased capacity to respond to an oxidative challenge. HFCS-55 induced a downregulation of the insulin signaling pathway, as indicated by attenuated (ser473)phosphorylation of AKT1. The c-Jun amino-terminal kinase (JNK), which is intimately linked to insulin resistance, was also activated; and this was accompanied by an increase in endoplasmic reticulum (ER) stress and intracellular free calcium perturbation. Hepatocytes exposed to HFCS-55 exhibited mitochondrial dysfunction and released cytochrome C (CytC) into the cytosol. Hepatic steatosis and mitochondrial disruption was induced in vivo by a diet enriched with 20% HFCS 55; accompanied by hypoadiponectinemia and elevated fasting serum insulin and retinol-binding protein-4 (RBP4) levels. Taken together our findings indicate a potential mechanism by which HFCS-55 may contribute to the pathogenesis of NAFLD.

Visceral obesity and hypoadiponectinemia are significant determinants of hepatic dysfunction: An epidemiologic study of 3827 Japanese subjects

BACKGROUND AND AIM

Adiponectin is an anti-inflammatory and insulin-sensitizing adipocytokine, and its serum concentrations are reduced in obesity with visceral fat accumulation. Visceral fat accumulation is an independent determinant of elevated serum liver enzymes. Hypoadiponectinemia plays important roles in the clinical progression of nonalcoholic steatohepatitis. The aim of this study was to evaluate the relation between visceral fat area (VFA), serum adiponectin concentration, and biochemical liver tests, such as aspartate aminotransferase, alanine aminotransferase (ALT), and gamma-glutamyltransferase (GGT) in normal subjects.

METHODS

The study group comprised 3827 Japanese subjects [mean age+/-SD; 47.6+/-10.7 y: 2854 males (48.4+/-10.7 y), 973 females (45.3+/-10.1 y)], who underwent annual health checkup in 2004. In addition to parameters measured in the annual health checkup, VFA and serum adiponectin concentration were measured by the bioelectrical impedance analysis method and a latex particle-enhanced turbidimetric assay system, respectively.

RESULTS

Pearson's correlation analysis showed a significant correlation between VFA and the levels of the above 3 liver enzymes in both sexes, and a significant negative correlation between adiponectin and all biochemical liver tests in men and with ALT and GGT in women. Stepwise multiple regression analysis showed that VFA was a significant determinant of serum liver tests in both sexes. Moreover, serum adiponectin concentration significantly and negatively influenced male ALT and GGT and female GGT.

CONCLUSIONS

Both visceral obesity and hypoadiponectinemia are significant determinants of subtle and asymptomatic hepatic dysfunction in normal Japanese subjects.

Adipokine serum levels are related to liver histology in severely obese patients undergoing bariatric surgery

BACKGROUND

Leptin, adiponectin, and resistin are adipokines linked to the development of insulin resistance, which plays a central role in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). We aimed to define adipokine serum levels in severely obese patients undergoing bariatric surgery and to correlate these with anthropometric and metabolic variables, liver function tests, and histopathological parameters of NAFLD and nonalcoholic steatohepatitis (NASH).

METHODS

Surgical liver biopsies were obtained from 50 bariatric patients with no history of liver disease or significant alcohol consumption. Serum leptin, adiponectin, and resistin levels were measured, and histology was assessed using Brunt's and Kleiner's scoring systems.

RESULTS

Waist/hip ratio was significantly higher in men (p = 0.0001), and leptin (p = 0.036) and adiponectin (p = 0.0001) serum levels were higher in women. Forty-one of 50 patients (82%) had histological NAFLD, including 10 (20%) with NASH. Nine patients (18%) had normal liver histology (obese control subgroup). In NAFLD patients, serum adiponectin was negatively correlated with activity grade and fibrosis stage, resistin was negatively correlated with steatosis grade (p = 0.033), while leptin was not related to histology. Leptin/adiponectin ratio showed positive association with stage (p = 0.044). In the subgroup of NASH patients, adiponectin was negatively correlated only with stage (p = 0.01), while there was no correlation between leptin, resistin, or leptin/adiponectin and histology.

CONCLUSIONS

Serum adiponectin and resistin levels are related to liver histology in bariatric patients and may be indicative of the histological severity of NAFLD and the extent of hepatic steatosis, respectively. Serum leptin levels are not informative of underlying liver histology in severely obese patients.

Elevated adiponectin serum levels in patients with chronic alcohol abuse rapidly decline during alcohol withdrawal

BACKGROUND

Adiponectin is a circulating protein with hepatoprotective effects.

AIMS

To study the relationship of excessive alcohol consumption and serum adiponectin levels (SAL).

PATIENTS AND METHODS

The SAL were determined in (i) heavy drinkers without advanced liver damage during the course of alcohol withdrawal, (ii) patients with chronic hepatitis C virus (HCV) infection, (iii) patients with alcohol-associated cirrhosis, and (iv) healthy volunteers that consumed excessive amounts of alcohol for only a short period of time. Further, primary human hepatocytes (PHH) and adipocytes were incubated in vitro with alcohol or serum of patients.

RESULTS

Patients with chronic alcohol consumption had significantly higher SAL than HCV-patients with comparable degrees of liver damage. In alcoholics, but not in HCV patients, SAL positively correlated with serum levels of aminotransferases. Further, SAL correlated with the amount of alcohol consumption but declined during the course of alcohol abstinence. After short-term excessive alcohol consumption SAL were not elevated in healthy individuals. Adiponectin mRNA was detectable in adipocytes but not in hepatocytes, and alcohol failed to induce adiponectin in both cell types. In contrast, serum of active drinkers induced adiponectin expression in adipocytes while serum from the same individuals collected after alcohol withdrawal had no effect.

CONCLUSIONS

Alcohol exhibits a specific effect on SAL that is dose and time dependent, and correlates with the degree of hepatic damage. Alcohol does not seem to affect adiponectin expression directly in adipocytes but potentially via mediators systemically released as a result of the chronic alcohol intake.

Mitochondrial dysfunction contributes to the increased vulnerabilities of adiponectin knockout mice to liver injury

Adiponectin is an adipocyte-derived hormone with a wide range of beneficial effects on obesity-related medical complications. Numerous epidemiological investigations in diverse ethnic groups have identified a lower adiponectin level as an independent risk factor for nonalcoholic fatty liver diseases and liver dysfunctions. Animal studies have demonstrated that replenishment of adiponectin protects against various forms of hepatic injuries, suggesting it to be a potential drug candidate for the treatment of liver diseases. This study was designed to investigate the cellular and molecular mechanisms underlying the hepatoprotective effects of adiponectin. Our results demonstrated that in adiponectin knockout (ADN-KO) mice, there was a preexisting condition of hepatic steatosis and mitochondrial dysfunction that might contribute to the increased vulnerabilities of these mice to secondary liver injuries induced by obesity and other conditions. Adenovirus-mediated replenishment of adiponectin depleted lipid accumulation, restored the oxidative activities of mitochondrial respiratory chain (MRC) complexes, and prevented the accumulation of lipid peroxidation products in ADN-KO mice but had no obvious effects on mitochondrial biogenesis. The gene and protein levels of uncoupling protein 2 (UCP2), a mitochondrial membrane transporter, were decreased in ADN-KO mice and could be significantly up-regulated by adiponectin treatment. Moreover, the effects of adiponectin on mitochondrial activities and on protection against endotoxin-induced liver injuries were significantly attenuated in UCP2 knockout mice.

CONCLUSION

These results suggest that the hepatoprotective properties of adiponectin are mediated at least in part by an enhancement of the activities of MRC complexes through a mechanism involving UCP2.

Fatty liver and chronic inflammation in Chinese adults

OBJECTIVE

To investigate the significance of fatty liver as predictor of insulin resistance (IR) and chronic inflammation.

RESEARCH DESIGN AND METHODS

This cross-sectional study included 450 adults of Han Chinese origin aged >or=35. Excluded were cases with hepatitis B or C, alcoholic liver disease, or currently using thiazolidinedione. The volunteers were screened for the presence of the components of metabolic syndrome (MtS). IR index was estimated by the homeostasis model assessment. The fatty liver index was evaluated by computed tomography, calculated as the liver/spleen (L/S) ratio arrived at by averaging Hounsfield values obtained for five 3-mm slices. Serum levels of adiponectin, C-reactive protein (CRP), leptin, interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) were checked in 100 subjects with low-L/S ratio and 100 age- and sex-matched controls.

RESULTS

Fatty liver index correlated with all MtS traits and IR index. The values of L/S ratios in subjects with 0, 1, 2, 3 and >or=4 traits of MtS were 1.25+/-0.13, 1.18+/-0.16, 1.12+/-0.21, 1.05+/-0.25 and 0.92+/-0.25, respectively (p<0.001). In our stepwise regression analysis to compare the L/S ratios to the conventional traits of MtS for association with adipokine dysregulation, we found L/S ratio to be independently associated with most of them: adiponectin (p<0.001), CRP (p<0.001), IL-6 (p=0.005) and TNF-alpha (p=0.014).

CONCLUSION

In Chinese, fatty liver index correlated well with IR index and can be a better marker of chronic inflammation than the conventional components of MtS.

Improvement of induction method of non-alcoholic fatty liver model in rats

AIM: To establish a rapid rat model of non-alcoholic fatty liver.

METHODS: Twenty-four male Sprague Dawley rats were averagely and randomly divide into group A, B and C, fed with normal diet, routine high-fat diet and routine high-fat diet plus sucrose, propylthiouracil, and sodium cholate, respectively. The general conditions and weight changes were dynamically observed for 5 wk, and then all the rats were killed. The pathological changes of liver tissues were observed by HE staining, and Sudan IV staining and electron microscopy were used to investigate the presence status of cytoplasmic lipid droplets in liver cells. The following indexes were compared between the three groups, including serum levels of triglyceride (TG), total cholesterol (TC), alanine aminotransferase (ALT), aspartate aminotransferase (AST), malondialdehyde (MDA), and superoxide dismutase (SOD), and tissue contents of TG and TC.

RESULTS: Starting from the fourth week, the weights of rats were significantly decreased in group A and C as compared with those in group B (249.63 ± 34.25, 241.88 ± 20.75 vs 275.38 ± 6.59, P < 0.05), but there was no marked difference between group A and C (P > 0.05). In the 5^th week, light microscopy showed a great number of fatty vacuoles in liver cells, and electron microscopy confirmed the presence of abundant lipid droplets. Different degrees of hepatic fatty degeneration (+~+++) was observed in group C (H = 13.36, P = 0.0003), but not in group A and B. The serum levels of TG, TC, ALT and MDA were markedly higher in group C than those in group A and B (TG: 1.28 ± 0.61 mmol/L vs 0.72 ± 0.12, 0.76 ± 0.04 mmol/L; TC: 12.78 ± 1.47 mmol/L vs 1.71 ± 0.03, 2.31 ± 0.49 mmol/L; ALT: 1518.64 ± 186.04 nkat/L vs 1181.57 ± 37.84, 1262.92 ± 159.20 nkat/L; MDA: 13.40 ± 4.24 μmol/L vs 5.89 ± 1.05, 7.23 ± 1.15 μmol/L; all P < 0.05), but the activity of SOD was lower in group C (5.21 ± 0.81 nkat/mL vs 11.91 ± 2.69, 11.19 ± 0.78 nkat/mL, P < 0.05). There were no notable differences between group A and B (P > 0.05). The tissue contents of TG and TC were dramatically higher both in group B and C than those in group A (TG: 2.14 ± 0.26, 5.83 ± 1.42 mmol/L vs 1.20 ± 0.16 mmol/L, P < 0.05; TC: 3.19 ± 0.23, 9.63 ± 1.12 mmol/L vs 2.13 ± 0.16 mmol/L, P < 0.05), and there was also statistical difference between group B and C (P < 0.05).

CONCLUSION: The rat model of non-alcoholic fatty liver can be successfully established within 5 wk by the improved method, which needs less time and cost during the construction, and basically simulating the occurrence and progression of non-alcoholic fatty liver in human beings.