Alpha2-Heremans-Schmid glycoprotein/fetuin-A is associated with insulin resistance and fat accumulation in the liver in humans

Matrix γ-carboxyglutamate protein and Fetuin-A, in wet type age-related macular degeneration

AIM

To evaluate the high sensitivity C-reactive protein (hsCRP), Fetuin-A and matrix γ-carboxyglutamate protein (MGP) as the main factors for vascular calcification and inflammation in serum of patients with advanced age-related macular degeneration (ARMD) in comparison to healthy controls.

METHODS

The subjects were 40 patients with choroidal neovascularization (CNV) having a mean age of 70.9±9.1y and a matched group of 49 apparently healthy control subjects. The ARMD was diagnosed using a slit-lamp with superfield lens, fundus photography and fluorescein angiography. Measurement of hsCRP was done by nephelometry method. Levels of Fetuin-A and MGP were measured by enzyme-linked immunosorbent assay (ELISA) technique.

RESULTS

hsCRP [0.45(0.07-2.63) mg/L vs 0.25(0.03-1.2) mg/L, P=0.02)] and Fetuin-A levels (50.27±5.04 vs 44.99±10.28 ng/mL, P=0.009) were higher in the patients than in the control groups. We could not find significant difference in MGP level between two groups (P=0.08). There was not a significant correlation between MGP with Fetuin-A and hsCRP among the patients (P=0.7, P=0.9 respectively). A significant negative correlation of hsCRP with Fetuin-A was observed in both case and control groups (P=0.004, r=-0.33 and P=0.001, r=-0.54, respectively).

CONCLUSION

Although our study shows that serum hsCRP and Fetuin-A is increased in CNV patients as well as negatively correlated with both study groups, their direct role on pathogenesis of ARMD required future studies.

Biomarkers of insulin sensitivity and insulin resistance: Past, present and future

Insulin resistance in insulin target tissues including liver, skeletal muscle and adipose tissue is an early step in the progression towards type 2 diabetes. Accurate diagnostic parameters reflective of insulin resistance are essential. Longstanding tests for fasting blood glucose and HbA1c are useful and although the hyperinsulinemic euglycemic clamp remains a "gold standard" for accurately determining insulin resistance, it cannot be implemented on a routine basis. The study of adipokines, and more recently myokines and hepatokines, as potential biomarkers for insulin sensitivity is now an attractive and relatively straightforward approach. This review discusses potential biomarkers including adiponectin, RBP4, chemerin, A-FABP, FGF21, fetuin-A, myostatin, IL-6, and irisin, all of which may play significant roles in determining insulin sensitivity. We also review potential future directions of new biological markers for measuring insulin resistance, including metabolomics and gut microbiome. Collectively, these approaches will provide clinicians with the tools for more accurate, and perhaps personalized, diagnosis of insulin resistance.

Exendin-4 Inhibits the Expression of SEPP1 and Fetuin-A via Improvement of Palmitic Acid-Induced Endoplasmic Reticulum Stress by AMPK

BACKGROUND

Selenoprotein P (SEPP1) and fetuin-A, both circulating liver-derived glycoproteins, are novel biomarkers for insulin resistance and nonalcoholic fatty liver disease. However, the effect of exendin-4 (Ex-4), a glucagon-like peptide-1 receptor agonist, on the expression of hepatokines, SEPP1, and fetuin-A, is unknown.

METHODS

The human hepatoma cell line HepG2 was treated with palmitic acid (PA; 0.4 mM) and tunicamycin (tuni; 2ug/ml) with or without exendin-4 (100 nM) for 24 hours. The change in expression of PA-induced SEPP1, fetuin-A, and endoplasmic reticulum (ER) stress markers by exendin-4 treatment were evaluated using quantitative real-time reverse transcription polymerase chain reaction and Western blotting. Transfection of cells with AMP-activated protein kinase (AMPK) small interfering RNA (siRNA) was performed to establish the effect of exendin-4-mediated AMPK in the regulation of SEPP1 and fetuin-A expression.

RESULTS

Exendin-4 reduced the expression of SEPP1, fetuin-A, and ER stress markers including PKR-like ER kinase, inositol-requiring kinase 1α, activating transcription factor 6, and C/EBP homologous protein in HepG2 cells. Exendin-4 also reduced the expression of SEPP1 and fetuin-A in cells treated with tunicamycin, an ER stress inducer. In cells treated with the AMPK activator 5-aminoidazole-4-carboxamide ribonucleotide (AICAR), the expression of hepatic SEPP1 and fetuin-A were negatively related by AMPK, which is the target of exendin-4. In addition, exendin-4 treatment did not decrease SEPP1 and fetuin-A expression in cells transfected with AMPK siRNA.

CONCLUSION

These data suggest that exendin-4 can attenuate the expression of hepatic SEPP1 and fetuin-A via improvement of PA-induced ER stress by AMPK.

Associations of Erythrocyte Fatty Acids in the De Novo Lipogenesis Pathway with Proxies of Liver Fat Accumulation in the EPIC-Potsdam Study

Background

Biomarker fatty acids (FAs) reflecting de novo lipogenesis (DNL) are strongly linked to the risk of cardiometabolic diseases. Liver fat accumulation could mediate this relation. There is very limited data from human population-based studies that have examined this relation.

Objective

The aim of this study was to investigate the relation between specific FAs in the DNL pathway and liver fat accumulation in a large population-based study.

Methods

We conducted a cross-sectional analysis of a subsample (n = 1,562) of the EPIC-Potsdam study, which involves 27,548 middle-aged men and women. Baseline blood samples have been analyzed for proportions of 32 FAs in erythrocyte membranes (determined by gas chromatography) and biomarker concentrations in plasma. As indicators for DNL, the DNL-index (16:0 / 18:2n-6) and proportions of individual blood FAs in the DNL pathway were used. Plasma parameters associated with liver fat content (fetuin-A, ALT, and GGT) and the algorithm-based fatty liver index (FLI) were used to reflect liver fat accumulation.

Results

The DNL-index tended to be positively associated with the FLI and was positively associated with GGT activity in men (p for trend: 0.12 and 0.003). Proportions of 14:0 and 16:0 in erythrocytes were positively associated with fetuin-A, whereas 16:1n-7 were positively associated with the FLI and GGT activity (all p for trends in both sexes at least 0.004). Furthermore, the proportion of 16:1n-7 was positively related to fetuin-A in women and ALT activity in men (all p for trend at least 0.03). The proportion of 16:1n-9 showed positive associations with the FLI and GGT activity in men and fetuin-A in both sexes, whereas 18:1n-7 was positively associated with GGT activity in men (all p for trend at least 0.048).

Conclusion

Findings from this large epidemiological study suggest that liver fat accumulation could link erythrocyte FAs in the DNL pathway to the risk of cardiometabolic diseases.

Increased adipose tissue secretion of Fetuin-A, lipopolysaccharide-binding protein and high-mobility group box protein 1 in metabolic syndrome

OBJECTIVE

Adipose Tissue (AT) dysregulation contributes to the pro-inflammatory state and insulin resistance of Metabolic Syndrome (MetS). We examined AT secretion of the hepatokine, Fetuin-A, LBP, sCD14 and HMGB-1, and toll-like receptor 2 and 4 protein levels in MetS and controls.

DESIGN AND METHODS

Secreted levels of Fetuin-A, LBP, HMGB-1 and sCD14 and TLR2 and TLR4 protein in AT of controls and MetS patients were assayed. Also mRNA and protein for Fetuin-A, LBP, sCD14 and HMGB-1 were studied in subcutaneous fat depot of mice and during adipocyte differentiation.

RESULTS

Secretion of Fetuin-A, LBP and HMGB-1 from AT were significantly increased in MetS (n = 28) compared to controls (n = 25), even after adjustment for adiposity. There were no significant differences in sCD14. Both LBP and Fetuin-A correlated significantly with HOMA-IR and increased significantly with increasing features of MetS. There was a significant increase in AT TLR2 and TLR4 protein in MetS compared to controls. Expression of Fetuin-A and LBP were significantly higher in subcutaneous white adipose tissue of HFD fed mice as well as in ob/ob mice compared to C57BL6/J control mice (n = 6 per group). Additionally mRNA and protein levels of FetA, LBP and HMGB-1 increased during differentiation of 3T3-L1 adipocytes.

CONCLUSIONS

We make the novel observation of increased secretion of Fetuin A, LBP and HMGB-1 from AT and hypothesize that these engage TLRs in AT and other tissues contributing to the pro-inflammatory state and insulin resistance of MetS.

Fetuin-A (AHSG) and its usefulness in clinical practice. Review of the literature

BACKGROUND

Fetuin-A, also called Alpha 2-Heremans Schmid Glycoprotein, is a multifunctional plasma agent what has been proven in animal and human studies. It plays a role as a physiological inhibitor of insulin receptor tyrosine kinase associated with insulin resistance and a negative acute phase reactant. It also regulates bone remodeling and calcium metabolism being an important inhibitor of calcium salt precipitation and vascular calcifications.

METHODS

PubMed database was searched for articles from 2002 up to December 2014 to identify the role of fetuin-A in the pathogenesis of selected internal diseases.

RESULTS

Due to secretion of fetuin-A mainly by the liver, it may be a marker of liver function and predictor of mortality in patients with cirrhosis and hepatocellular cancer. The associations between high fetuin-A and metabolic syndrome as well as its hepatic manifestation- nonalcoholic fatty liver disease and atherogenic lipid profile have been well proven. However, fetuin-A relation with BMI is not so clear. Contrary to few reports, many authors suggest that fetuin-A may be an independent risk factor for type 2 diabetes and marker of diabetic complications. Close associations of high and low fetuin-A concentrations with cardiovascular diseases and mortality risk have been reported which is explained by differences in analyzed populations, stages of atherosclerosis and calcifications, coexistence of type 2 diabetes or kidney dysfunction and different main pathways of fetuin-A actions in various diseases.

CONCLUSIONS

Fetuin-A has a diagnostic potential as a biomarker for liver dysfunction, cardiovascular diseases and disorders associated with metabolic syndrome.

Fetuin-A 742 (C/T) and 766 (C/G) polymorphic sites are associated with increased risk of myocardial infarction in older patients (≥ 40 years of age)

Inflammation and genetics have key roles in the pathogenesis of atherosclerosis, and the etiology of myocardial infarction (MI). Recent studies have indicated that lower serum levels of fetuin-A may accelerate the vascular mineralization process, which leads to pathophysiological conditions, such as coronary heart disease and chronic renal failure. The aim of the present study was to evaluate the association between specific fetuin-A polymorphisms (742 and 766) that are associated with circulating serum levels, and MI cases. The study consisted of 292 participants; 146 healthy control subjects and 146 patients with MI. The patient group was divided into two subgroups: 56 MI ≤ 40 years and 90 MI ≥ 40 years. The genotype distribution of fetuin 742 (C/T) and fetuin 766 (C/G) were determined by restriction enzyme digestion of polymerase chain reaction products. A significant difference was determined between the patients with MI and the control subjects with regards to fetuin-A 742 C/T gene polymorphism (P=0.028), regardless of age. Genotype distributions of fetuin-A 742 (C/G, P=0.004) and 766 (C/T, P=0.017) were statistically different in the older patients with MI (MI ≥ 40 years old), as compared with the healthy controls; however, there were no significant differences between the younger patients with MI and the controls, with regards to fetuin-A 742 C/T (P=0.519) and 766 C/G (P=0.653) gene polymorphisms. In addition, an association was observed between the presence of fetuin-A 742 T and 766 G alleles, and MI cases. The present study demonstrates that fetuin-A 742 (C/T) and 766 (C/G) genotypes may be risk factors for MI in patients older than 40 years of age.

Prediabetes and associated disorders

Prediabetes represents an elevation of plasma glucose above the normal range but below that of clinical diabetes. Prediabetes includes individuals with IFG, IGT, IFG with IGT and elevated HbA1c levels. Insulin resistance and β-cell dysfunction are characteristic of this disorder. The diagnosis of prediabetesis is vital as both IFG and IGT are indeed well-known risk factors for type 2 diabetes with a greater risk in the presence of combined IFG and IGT. Furthermore, as will be illustrated in this review, prediabetes is associated with associated disorders typically only considered in with established diabetes. These include cardiovascular disease, periodontal disease, cognitive dysfunction, microvascular disease, blood pressure abnormalities, obstructive sleep apnea, low testosterone, metabolic syndrome, various biomarkers, fatty liver disease, and cancer. As the vast majority of individuals with prediabetes are unaware of their diagnosis, it is therefore vital that the associated conditions are identified, particularly in the presence of mild hyperglycemia, so they may benefit from early intervention.

Evaluation of fetuin-A and carotid intima-media thickness in adolescent type 1 diabetic patients

OBJECTIVE

To evaluate fetuin-A level and carotid intima-media thickness (CIMT) in adolescent type 1 diabetics.

PATIENTS AND METHODS

The study included 62 type 1 diabetic patients and 30 healthy volunteers of the same age and sex. Blood sample was taken for assessment of glycosylated hemoglobin (HbA1), lipid profile, and fetuin-A. Urine sample was also taken for assessment of albumin/creatinine ratio. Anthropometric measurements were taken, including weight, height, and waist and hip circumference. CIMT was assessed for all patients and controls.

RESULTS

Serum fetuin-A, Rt., Lt. and both CIMT were significantly higher in diabetics. Fetuin-A had a significant positive correlation with duration of disease, waist and hip circumference, BMI, BMI SDS, waist/height ratio, Rt., Lt. and both CIMT. Stepwise multiple regression analysis revealed that the duration of disease, waist/height ratio, and HDL-c were the factors related to fetuin-A.

CONCLUSION

Adolescent type 1 diabetic patients have high fetuin-A levels and increased CIMT, with the latter representing the development of early atherosclerosis. In this light, adolescents with type 1 diabetes require frequent follow up for early detection of atherosclerosis.

Serum fetuin-A and arginase-1 in human obesity model: Is there any interaction between inflammatory status and arginine metabolism?

Obesity is a major risk factor for many chronic metabolic diseases such as inflammation, insulin resistance (IR) and fatty liver injury. It was reported that obesity causes some variations on the serum levels of fetuin-A and is associated with arginine metabolism, especially arginase-1 levels. The aim of our study was to evaluate, the interaction and possible changes of these liver over produced proteins, fetuin-A and arginase-1 levels in obesity-related inflammatory status. Study groups were composed of individuals aged between 19 and 63 (n = 62). The control group included healthy subjects with BMI < 25, obese group included obese patients with BMI > 30 and with no other chronic disease. Biochemical markers were determined by an auto-analyzer. Adiponectin, fetuin-A, arginase-1, asymmetric dimethylarginine (ADMA), arginine, Hexanoyl-lysine (HEL) and leptin levels were measured with commercial ELISA immunoassay kits. Nitrite and nitrate were determined with colorimetric assay kit in serum samples. High sensitive C-reactive protein (hsCRP) levels and liver function enzymes activities were higher in the obese group in respect to the control group. Serum fetuin-A, arginase-1 and leptin levels were increased but adiponectin levels were decreased in obese subjects. Fetuin-A levels showed significant correlations with arginase-1 and HOMA-IR. Consequently, we carried out an investigation about higher serum fetuin-A and arginase-1 levels may have an important role in obesity and obesity-related liver damage.

The effects of omega-3 fatty acid on vitamin D activation in hemodialysis patients: a pilot study

The high incidence of cardiovascular disease and vitamin D deficiency in chronic kidney disease patients is well known. Vitamin D activation by omega-3 fatty acid (FA) supplementation may explain the cardioprotective effects exerted by omega-3 FA. We hypothesized that omega-3 FA and 25-hydroxyvitamin D (25(OH)D) supplementation may increase 1,25-dihydroxyvitamin D (1,25(OH)₂D) levels compared to 25(OH)D supplementation alone in hemodialysis (HD) patients that have insufficient or deficient 25(OH)D levels. We enrolled patients that were treated for at least six months with 25(OH)D < 30 ng/mL (NCT01596842). Patients were randomized to treatment for 12 weeks with cholecalciferol supplemented with omega-3 FA or a placebo. Levels of 25(OH)D and 1,25(OH)₂D were measured after 12 weeks. The erythrocyte membrane FA contents were also measured. Levels of 25(OH)D were increased in both groups at 12 weeks compared to baseline. The 1,25(OH)₂D levels at 12 weeks compared to baseline showed a tendency to increase in the omega-3 FA group. The oleic acid and monounsaturated FA content decreased, while the omega-3 index increased in the omega-3 FA group. Omega-3 FA supplementation may be partly associated with vitamin D activation, although increased 25(OH)D levels caused by short-term cholecalciferol supplementation were not associated with vitamin D activation in HD patients.

Serum fetuin-A concentrations are positively associated with serum VEGF levels in patients with newly diagnosed type 2 diabetes

Fetuin-A was considered to be involved in pathogenesis of type 2 diabetes. On the other hand, higher vascular endothelial growth factor (VEGF) expression is associated with diabetes and its vascular complications, but the mechanisms leading to higher VEGF levels are still not clear. To the best of our knowledge, there are no data to show the associations between fetuin-A and VEGF in patients with type 2 diabetes. Therefore, the aim of this study is to investigate the relationship between serum fetuin-A concentrations and serum VEGF levels in patients with type 2 diabetes. We recruited 345 patients with newly diagnosed type 2 diabetes. Serum fetuin-A concentrations and serum VEGF levels were measured using enzyme-linked immunosorbent assay (ELISA) method. In this study, there was a significant positive correlation between serum fetuin-A concentrations and serum VEGF levels (r=0.223, P<0.001), and the correlation remained significant even after adjustment for other confounding factors in the multivariate regression model (β=0.151, P=0.006). Mantel-Haenszel (M-H) stratified analysis showed that the degree of association of high concentrations of fetuin-A with high levels of VEGF is higher than that with low levels of VEGF (odds ratio of M-H [ORM-H], 2.938; 95% confidence interval [CI], 1.896-4.553). In addition, this study showed that both fetuin-A and VEGF were positively associated with fasting plasma glucose (FPG), glycated hemoglobin A1c (HbA1c) and C-reactive protein (CRP). These data suggested that serum fetuin-A concentrations were positively associated with serum VEGF levels in patients with newly diagnosed type 2 diabetes.

The relationship of circulating fetuin-a with liver histology and biomarkers of systemic inflammation in nondiabetic subjects with nonalcoholic fatty liver disease

BACKGROUND/AIMS

Fetuin-A, a glycoprotein with anti-inflammatory properties, plays an important role in counter-regulating inflammatory responses. It has also been associated with insulin resistance and metabolic syndrome. We aimed to investigate circulating concentrations of fetuin-A and its possible association with hepatic and systemic inflammation in nondiabetic subjects with nonalcoholic fatty liver disease (NAFLD).

PATIENTS AND METHODS

We included 105 nondiabetic male subjects with NAFLD [nonalcoholic steatohepatitis (NASH, n = 86) and simple steatosis (SS, n = 19)]. Plasma levels of fetuin-A and markers of inflammation [high-sensitive C reactive protein (hsCRP), tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), and adiponectin] were measured by enzyme-linked immunosorbent assay method. Insulin sensitivity was determined by homeostasis model assessment of insulin resistance (HOMA-IR) index.

RESULTS

Fetuin-A was negatively correlated with age (r = -0.27, P = 0.006), however there was no association between fetuin-A and body mass index, waist circumference (WC), glucose, insulin, HOMA-IR, lipid parameters, and inflammatory markers. In addition, no significant association was observed between fetuin-A and histological findings including liver fibrosis.

CONCLUSION

This study demonstrated that plasma fetuin-A levels are not correlated with the hepatic histology and systemic markers of inflammation in nondiabetic subjects with NAFLD. Our data also suggested that age is significantly associated with fetuin-A in this clinically relevant condition.

Fetuin-A: a novel link between obesity and related complications

Fetuin-A (FetA) is a 64-kDa glycoprotein that is secreted from both the liver and adipose tissue. Circulating FetA is elevated in obesity and related disorders including type 2 diabetes mellitus, nonalcoholic fatty liver disease and the metabolic syndrome; and a FetA-related parameter, caliciprotein particle, is highly relevant to vascular calcification in overweight/obese patients with chronic kidney disease. FetA level is also associated with impaired insulin sensitivity and glucose tolerance. Accumulating evidence suggests that elevated FetA level causes impaired glycemic control, as FetA has been implicated in impairment of insulin receptor signaling, toll-like receptor 4 activation, macrophage migration and polarization, adipocyte dysfunction, hepatocyte triacylglycerol accumulation and liver inflammation and fibrosis. Weight loss, aerobic exercise, metformin and pioglitazone have each been shown to be effective for reducing FetA level.

The human colostrum whey proteome is altered in gestational diabetes mellitus

Proteomics of human milk has been used to identify the comprehensive cargo of proteins involved in immune and cellular function. Very little is known about the effects of gestational diabetes mellitus (GDM) on lactation and breast milk components. The objective of the current study was to examine the effect of GDM on the expression of proteins in the whey fraction of human colostrum. Colostrum was collected from women who were diagnosed with (n = 6) or without (n = 12) GDM at weeks 24-28 in pregnancy. Colostral whey was analyzed for protein abundances using high-resolution, high-mass accuracy liquid chromatography tandem mass spectrometry. A total of 601 proteins were identified, of which 260 were quantified using label free spectral counting. Orthogonal partial least-squares discriminant analysis identified 27 proteins that best predict GDM. The power law global error model corrected for multiple testing was used to confirm that 10 of the 27 proteins were also statistically significantly different between women with versus without GDM. The identified changes in protein expression suggest that diabetes mellitus during pregnancy has consequences on human colostral proteins involved in immunity and nutrition.

Phosphorylation of sterol regulatory element-binding protein (SREBP)-1c by p38 kinases, ERK and JNK influences lipid metabolism and the secretome of human liver cell line HepG2

The transcription factor sterol regulatory element binding protein (SREBP)-1c plays a pivotal role in lipid metabolism. In this report we identified the main phosphorylation sites of MAPK-families, i.e. p38 stress-activated MAPK (p38), ERK-MAPK (ERK) or c-JUN N-terminal protein kinases (JNK) in SREBP-1c. The major phosphorylation sites of p38, i.e. serine 39 and threonine 402, are identical to those we recently identified in the splice-variant SREBP-1a. In contrast, ERK and JNK phosphorylate SREBP-1c at two major sites, i.e. threonine 81 and serine 93, instead of one site in SREBP-1a. Functional analyses of the biological outcome in the human liver cell line HepG2 reveals SREBP-1c phosphorylation dependent alteration in lipid metabolism and secretion pattern of lipid transporting proteins, e.g. ApoE or ApoA1. These results suggest that phosphorylation of SREBP-1c by different MAPKs interferes with lipid metabolism and the secretory activity of liver cells.

Relationship of apelin, procalcitonin, and fetuin-A concentrations with carotid intima-media thickness in acromegaly

Background

Acromegaly is characterized by excess growth hormone and insulin-like growth factor-1 concentrations. There is conflicting evidence as to whether acromegaly is associated with an increased risk of atherosclerosis. Apelin is an adipose tissue-derived peptide that may be associated with hyperinsulinemia. Fetuin-A is a hepatocyte produced plasma glycoprotein that has an important role as a calcification inhibitor. The aim of this study was to examine apelin, fetuin-A, and procalcitonin concentrations and to assess their relationship with carotid intima medial thickness (cIMT) in subjects with acromegaly.

Methods

Apelin, fetuin-A, and procalcitonin serum concentrations were measured in 37 (20 inactive and 17 active) subjects with acromegaly and 30 control subjects, along with carotid intima medial thickness.

Results

The concentrations of apelin, fetuin-A, and procalcitonin were increased in subjects with acromegaly. There were significant correlations between apelin, fetuin-A, and procalcitonin in subjects with acromegaly. Carotid intima medial thickness values were similar between control subjects and subjects with acromegaly.

Conclusions

Carotid intima medial thickness was not increased in subjects with acromegaly. It is possible that the increased apelin and fetuin-A concentrations observed play a protective role against the development of atherosclerosis in subjects with acromegaly.

Fetuin A/nutritional status predicts cardiovascular outcomes and survival in hemodialysis patients

BACKGROUND

Fetuin A - a predictor of cardiovascular (CV) outcomes in dialysis patients - is correlated with over-nutrition in the general population. Whether fetuin A and nutritional status interact with each other to alter CV outcomes and survival in hemodialysis (HD) patients remains unknown.

METHODS

We performed a prospective study on 388 prevalent HD patients. We used the geriatric nutritional risk index (GNRI) for the evaluation of nutritional status. Study outcomes included the occurrence of CV event, CV death, and all-cause mortality during follow-up; interactions between parameters for predicting outcomes were assessed by the interaction terms in a Cox regression model.

RESULTS

Overall, 131 patients experienced CV events and 92 patients died, with 51 CV deaths. HD patients with higher fetuin A levels had lower numbers of CV events (adjusted hazard ratio [HR], 0.9; 0.81-0.99) and all-cause mortality (adjusted HR, 0.97; 0.91-0.99). However, patients with higher GNRI had lower all-cause mortality (adjusted HR, 0.79; 0.51-0.98, for every 10-unit increase). Fetuin A levels and GNRI showed a significant interaction in the prediction of CV events (adjusted HR, 1.01; 1.008-1.02) but not for all-cause or CV mortality. In patients with poor nutritional status, higher fetuin A levels were associated with fewer CV events; however, in contrast, in subjects with better nutritional status, higher fetuin A levels appeared to lead to a higher number of CV events.

CONCLUSIONS

Fetuin A showed a remarkable interaction with nutritional status in evaluating the risks of CV morbidities in prevalent HD patients.

High plasma fetuin-A levels are associated with metabolic syndrome among males but not females in a Japanese general population

AIMS

Fetuin-A, a protein exclusively secreted from the liver, is associated with insulin resistance and/or metabolic syndrome (MetS). However, few studies have examined this association in Japan. We investigated this issue in a Japanese general population.

METHODS

We performed an epidemiological survey in a small community in Japan. The participants consisted of 659 subjects (253 males and 406 females). Fetuin-A levels were measured by a sandwich ELISA method and the modified NCEP-ATP III criteria were adopted to diagnose MetS. The homeostasis model assessment index (HOMA-IR) was calculated as a marker of insulin resistance.

RESULTS

Statistically significant characteristics of the 659 subjects stratified by fetuin-A quartiles were male gender (inversely), age (inversely), insulin, HOMA-IR, uric acid (inversely), alcohol intake (inversely) and the prevalence of MetS. Mean fetuin-A levels were 249.7±45.1μg/ml in males and 262.7±55.8μg/ml in females. In males, the prevalence of MetS was 43.1%, and their mean HOMA-IR level was 1.1. In females, the prevalence of MetS was 17.7%, and their mean HOMA-IR level was 0.9. Multiple stepwise regression analyses showed that fetuin-A levels in males but not females were independently associated with MetS and LDL-c. Multiple logistic regression analysis of fetuin-A (quartile 1 vs. quartile 4) in males showed significant odds ratios of 1.009 (95% C.I.: 1.003-1.015) for MetS and 1.376 (95% C.I.: 1.027-1.844) for 1-SD increment increase in LDL-c.

CONCLUSIONS

High plasma fetuin-A levels were associated with MetS in community-dwelling Japanese males but not females.

Association between fetuin-A levels with insulin resistance and carotid intima-media thickness in patients with new-onset type 2 diabetes mellitus

Fetuin-A, which is known to inhibit insulin signaling and pathological calcification, has emerged as a diabetes risk biomarker. In the present study, the association between the fetuin-A levels with insulin resistance (IR) and carotid intima-media thickness (CIMT) was investigated in patients with new-onset type 2 diabetes mellitus (nT2DM). A total of 100 patients with nT2DM (nT2DM group) and 100 normal glucose tolerance (NGT group) controls were evaluated. The serum fetuin-A level was measured by a commercial solid-phase ELISA kit. The estimate of IR was calculated by homeostasis model assessment (HOMA-IR). CIMT was measured by B-mode ultrasound. The association between the serum fetuin-A levels and the metabolic parameters was also analyzed. The serum fetuin-A levels were increased significantly in the nT2DM group compared to the NGT group (368.5±15.6 mg/ml vs. 152.7±7.1 mg/ml, P<0.01). Fetuin-A was positively correlated with HOMA-IR, CIMT, glycated hemoglobin, triglyceride, low-density lipoprotein cholesterol, body mass index, systolic blood pressure, fasting blood glucose and 2 h post-glucose load blood glucose (P<0.05 and P<0.01), but negatively correlated with fasting plasma insulin, 2 h plasma insulin after glucose overload, high-density lipoprotein cholesterol and HOMA-β-cell insulin secretion index (P<0.05 and P<0.01). To the best of our knowledge, the study demonstrated for the first time that there is a significant association between the serum fetuin-A levels with IR and CIMT in nT2DM. These results indicate that serum fetuin-A levels can be used as independent markers in the diagnosis of macroangiopathies in nT2DM.

Inflammatory and metabolic biomarkers and risk of liver and biliary tract cancer

Obesity and associated metabolic disorders have been implicated in liver carcinogenesis; however, there are little data on the role of obesity-related biomarkers on liver cancer risk. We studied prospectively the association of inflammatory and metabolic biomarkers with risks of hepatocellular carcinoma (HCC), intrahepatic bile duct (IBD), and gallbladder and biliary tract cancers outside of the liver (GBTC) in a nested case-control study within the European Prospective Investigation into Cancer and Nutrition. Over an average of 7.7 years, 296 participants developed HCC (n=125), GBTC (n=137), or IBD (n=34). Using risk-set sampling, controls were selected in a 2:1 ratio and matched for recruitment center, age, sex, fasting status, and time of blood collection. Baseline serum concentrations of C-reactive protein (CRP), interleukin-6 (IL-6), C-peptide, total high-molecular-weight (HMW) adiponectin, leptin, fetuin-a, and glutamatdehydrogenase (GLDH) were measured, and incidence rate ratios (IRRs) and 95% confidence intervals (CIs) were estimated using conditional logistic regression. After adjustment for lifestyle factors, diabetes, hepatitis infection, and adiposity measures, higher concentrations of CRP, IL-6, C-peptide, and non-HMW adiponectin were associated with higher risk of HCC (IRR per doubling of concentrations=1.22; 95% CI=1.02-1.46; P=0.03; 1.90; 95% CI=1.30-2.77; P=0.001; 2.25; 95% CI=1.43-3.54; P=0.0005; and 2.09; 95% CI=1.19-3.67; P=0.01, respectively). CRP was associated also with risk of GBTC (IRR=1.22; 95% CI=1.05-1.42; P=0.01). GLDH was associated with risks of HCC (IRR=1.62; 95% CI=1.25-2.11; P=0.0003) and IBD (IRR=10.5; 95% CI=2.20-50.90; P=0.003). The continuous net reclassification index was 0.63 for CRP, IL-6, C-peptide, and non-HMW adiponectin and 0.46 for GLDH, indicating good predictive ability of these biomarkers.

CONCLUSION

Elevated levels of biomarkers of inflammation and hyperinsulinemia are associated with a higher risk of HCC, independent of obesity and established liver cancer risk factors.

Causal relationship between body mass index and fetuin-A level in the asian population: a bidirectional Mendelian randomization study

OBJECTIVE

Fetuin-A is associated with body mass index (BMI) as well as components of the metabolic syndrome. However, it is unclear if fetuin-A affects BMI or the other way around. We therefore assessed the causal association between fetuin-A and BMI or vice versa, utilizing a bidirectional Mendelian randomization approach.

DESIGN AND METHODS

This was a study of 2558 subjects from the Electricity Generating Authority of Thailand (EGAT) cohort. Two polymorphisms, that is, rs2248690 in the alpha2-Hereman-Schmid glycoprotein (AHSG) gene and rs9939609 in the fat mass and obesity-associated (FTO) gene were genotyped. Bidirectional causal models were constructed using a two-stage least-square instrumental variable (IV) regression. First, rs2248690 locus was used as the instrumental variable for the effect of circulating fetuin-A on BMI, and then, the FTO rs9939609 locus was used as the instrumental variable for the effect of BMI on circulating fetuin-A.

RESULTS

Among the 2558 subjects, the prevalence of the minor AHSG (T) and FTO (A) alleles was 17.9% and 22.1%, respectively. The AHSG rs2248690 locus was highly related to serum fetuin-A levels (P < 0.001). Likewise, the FTO rs9939609 locus and BMI were highly associated (P < 0.001). Mendelian randomization analyses showed that circulating fetuin-A, instrumented by the AHSG rs2248690 locus, was associated with BMI (coefficient = 2.26; 95% CI: 0.39, 4.12). In contrast, BMI, instrumented by the FTO rs9939609 locus, was not associated with circulating fetuin-A (coefficient = 0.0007; 95% CI: -0.0242, 0.0256).

CONCLUSION

Our findings suggest a causal association leading from circulating fetuin-A to BMI. There was no evidence of reverse causality from BMI to fetuin-A.

Hepatic steatosis and PNPLA3 I148M variant are associated with serum Fetuin-A independently of insulin resistance

BACKGROUND & AIMS

Fetuin-A is a liver-derived peptide associated with insulin resistance. Aim of this cross-sectional study was to evaluate whether Fetuin-A is increased in patients with nonalcoholic fatty liver disease (NAFLD) vs. healthy subjects without metabolic abnormalities and the association with insulin resistance and liver damage. To investigate the causal relationship between fatty liver and Fetuin-A, we also analysed whether the inherited I148M PNPLA3 variant modulates Fetuin-A.

METHODS

In 137 patients with histological NAFLD, complete metabolic characterization, PNPLA3 genotype, and in 260 healthy subjects without metabolic alterations, Fetuin-A was measured by enzyme-linked immunoabsorbent assay.

RESULTS

Serum Fetuin-A was higher in NAFLD patients than in controls (P < 0·0001), independently of age, sex, BMI, insulin resistance, dyslipidemia, adiponectin, PNPLA3 I148M and ALT levels (OR 1·006 95% CI 1·003-1·11; P = 0·003). In NAFLD patients, Fetuin-A was associated with steatosis severity (P = 0·03) and metabolic syndrome features, but not with hepatic inflammation. At multivariate analysis, Fetuin-A levels were associated with BMI, triglycerides, hyperglycemia and PNPLA3 I148M (P = 0·034) independently also of age, sex and ALT levels. As PNPLA3 I148M is a strong and inherited determinant of liver fat without affecting insulin resistance and lipid levels, these data suggest that steatosis has a causal role in determining serum Fetuin-A levels.

CONCLUSIONS

Liver fat accumulation and the I148M variant of PNPLA3 are associated with serum Fetuin-A levels independently of insulin resistance. Fetuin-A may be implicated in the pathogenesis of metabolic complications associated with NAFLD.

Circulating alanine transaminase (ALT) and γ-glutamyl transferase (GGT), but not fetuin-A, are associated with metabolic risk factors, at baseline and at two-year follow-up: the prospective Cyprus Metabolism Study

OBJECTIVE

To comparatively evaluate traditional liver tests and fetuin A as predictors of cardiometabolic risk, we studied associations between serum alanine transaminase (ALT), γ-glutamyl transferase (GGT), aspartate aminotransferase (AST) and fetuin-A and anthropometric, metabolic, and cardiovascular parameters cross-sectionally at baseline, and prospectively, after 2-years of follow-up.

RESEARCH DESIGN AND METHODS

616 randomly enrolled young healthy participants in the Cyprus Metabolism Study, including all 93 subjects who participated in the follow-up study 2 years after baseline assessment, were included in this study.

RESULTS

In the cross-sectional study, serum ALT and GGT were strongly correlated with anthropometric, cardiovascular, and metabolic variables, while serum AST was only correlated with waist circumference and waist-to-hip ratio. Fetuin-A was correlated with anthropometric variables, systolic blood pressure (SBP), insulin, and homeostasis model of assessment-insulin resistance (HOMA-IR) in the unadjusted model. In the fully adjusted model, both serum ALT and GGT levels remained positively correlated with total and low-density lipoprotein (LDL) cholesterol. GGT levels also remained correlated with triglycerides. ALT levels remained strongly positively correlated with insulin (r=0.17, p<.0001) and HOMA-IR (r=0.16, p=0.0001). Serum fetuin-A levels were no longer significantly correlated with any variables. Prospectively, ALT and GGT were predictors of anthropometric variables and LDL cholesterol, while baseline levels of AST and fetuin-A were not predictors of any variables at 2-year follow-up.

CONCLUSIONS

We confirmed associations of ALT and GGT levels but failed to demonstrate an independent association between fetuin-A and cardiometabolic risk factors in young healthy men. Traditional liver tests (LFTs) are thus better than fetuin-A predictors of metabolic risk factors cross-sectionally and prospectively in young healthy adults.

AMP-activated Protein Kinase (AMPK): Does This Master Regulator of Cellular Energy State Distinguish Insulin Sensitive from Insulin Resistant Obesity?

Although a correlation exists between obesity and insulin resistance, roughly 25 % of obese individuals are insulin sensitive. AMP-activated protein kinase (AMPK) is a cellular energy sensor that among its many actions, integrates diverse physiological signals to restore energy balance. In addition, in many situations it also increases insulin sensitivity. In this context, AMPK activity is decreased in very obese individuals undergoing bariatric surgery who are insulin resistant compared to equally obese patients who are insulin sensitive. In this review, we will both explore what distinguishes these individuals, and evaluate the evidence that diminished AMPK is associated with insulin resistance and metabolic syndrome-associated disorders in other circumstances.

Fetuin-A influences vascular cell growth and production of proinflammatory and angiogenic proteins by human perivascular fat cells

AIMS/HYPOTHESIS

Fetuin-A (alpha2-Heremans-Schmid glycoprotein), a liver-derived circulating glycoprotein, contributes to lipid disorders, diabetes and cardiovascular diseases. In a previous study we found that perivascular fat cells (PVFCs) have a higher angiogenic potential than other fat cell types. The aim was to examine whether fetuin-A influences PVFC and vascular cell growth and the expression and secretion of proinflammatory and angiogenic proteins, and whether TLR4-independent pathways are involved.

METHODS

Mono- and co-cultures of human PVFCs and endothelial cells were treated with fetuin-A and/or palmitate for 6-72 h. Proteins were quantified by ELISA and Luminex, mRNA expression by real-time PCR, and cell growth by BrDU-ELISA. Some PVFCs were preincubated with a nuclear factor κB NFκBp65 inhibitor, or the toll-like receptor 4 (TLR4) inhibitor CLI-095, or phosphoinositide 3-kinase (PI3K)/Akt inhibitors and/or stimulated with insulin. Intracellular forkhead box protein O1 (FoxO1), NFκBp65 and inhibitor of κB kinase β (IKKβ) localisation was visualised by immunostaining.

RESULTS

PVFCs expressed and secreted IL-6, IL-8, plasminogen activator inhibitor 1 (PAI-1), basic fibroblast growth factor (bFGF), platelet-derived growth factor (PDGF)-BB, monocyte chemotactic protein-1 (MCP-1), vascular endothelial growth factor (VEGF), placental growth factor (PLGF) and hepatocyte growth factor (HGF). Fetuin-A upregulated IL-6 and IL-8, and this was potentiated by palmitate and blocked by CLI-095. Immunostaining and electrophoretic mobility shift assay (EMSA) showed partial NFκBp65 activation. MCP-1 was upregulated and blocked by CLI-095, but not by palmitate. However, HGF was downregulated, which was slightly potentiated by palmitate. This effect persisted after TLR4 pathway blockade. Stimulation of insulin-PI3K-Akt signalling by insulin resulted in nuclear FoxO1 extrusion and HGF upregulation. Fetuin-A counteracted these insulin effects.

CONCLUSIONS/INTERPRETATION

Fetuin-A and/or palmitate influence the expression of proinflammatory and angiogenic proteins only partially via TLR4 signalling. HGF downregulation seems to be mediated by interference with the insulin-dependent receptor tyrosine kinase pathway. Fetuin-A may also influence angiogenic and proinflammatory proteins involved in atherosclerosis.

Ketosis onset type 2 diabetes had better islet β-cell function and more serious insulin resistance

Diabetic ketosis had been identified as a characteristic of type 1 diabetes mellitus (T1DM), but now emerging evidence has identified that they were diagnosed as T2DM after long time follow up. This case control study was aimed at comparing the clinical characteristic, β-cell function, and insulin resistance of ketosis and nonketotic onset T2DM and providing evidence for treatment selection. 140 cases of newly diagnosed T2DM patients were divided into ketosis (62 cases) and nonketotic onset group (78 cases). After correction of hyperglycemia and ketosis with insulin therapy, plasma C-peptide concentrations were measured at 0, 0.5, 1, 2, and 3 hours after 75 g glucose oral administration. Area under the curve (AUC) of C-peptide was calculated. Homoeostasis model assessment was used to estimate basal β-cell function (HOMA-β) and insulin resistance (HOMA-IR). Our results showed that ketosis onset group had higher prevalence of nonalcoholic fatty liver disease (NAFLD) than nonketotic group (P = 0.04). Ketosis onset group had increased plasma C-peptide levels at 0 h, 0.5 h, and 3 h and higher AUC(0-0.5), AUC₀₋₁, AUC₀₋₃ (P < 0.05). Moreover, this group also had higher HOMA-β and HOMA-IR than nonketotic group (P < 0.05). From these data, we concluded that ketosis onset T2DM had better islet β-cell function and more serious insulin resistance than nonketotic onset T2DM.

[The role of fetuin-A in cardiovascular diseases]

Fetuin-A (also known as α2-Heremans-Schmid glycoprotein) is a multifunctional molecule secreted by the liver. It is a negative acute phase reactant with a debated role in subclinical inflammation. Fetuin-A is an inhibitor of the insulin receptor and its serum level correlates with insulin resistance. The protein has been implicated in adipocyte dysfunction and it is associated with obesity and non-alcoholic fatty liver disease. Although all these properties seem to promote atherosclerosis, the role of fetuin-A in cardiovascular diseases is more complex. As a natural inhibitor of tissue and vascular calcification, fetuin-A also acts as a protective factor in atherosclerosis. The potential role and prognostic value of fetuin-A in arterial calcification and cardiovascular diseases is discussed in this review, along with explanations for seemingly contradicting results in the literature and possible directions for future research.

Impact of the adipokine adiponectin and the hepatokine fetuin-A on the development of type 2 diabetes: prospective cohort- and cross-sectional phenotyping studies

Background

Among adipokines and hepatokines, adiponectin and fetuin-A were consistently found to predict the incidence of type 2 diabetes, both by regulating insulin sensitivity.

Objective

To determine to what extent circulating adiponectin and fetuin-A are independently associated with incident type 2 diabetes in humans, and the major mechanisms involved.

Methods

Relationships with incident diabetes were tested in two cohort studies: within the European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam study (628 cases) and the Nurses' Health Study (NHS; 470 cases). Relationships with body fat compartments, insulin sensitivity and insulin secretion were studied in the Tübingen Lifestyle Intervention Program (TULIP; N = 358).

Results

Circulating adiponectin and fetuin-A, independently of several confounders and of each other, associated with risk of diabetes in EPIC-Potsdam (RR for 1 SD: adiponectin: 0.45 [95% CI 0.37–0.54], fetuin-A: 1.18 [1.05–1.32]) and the NHS (0.51 [0.42–0.62], 1.35 [1.16–1.58]). Obesity measures considerably attenuated the association of adiponectin, but not of fetuin-A. Subjects with low adiponectin and concomitantly high fetuin-A had the highest risk. Whereas both proteins were independently (both p<1.8×10⁻⁷) associated with insulin sensitivity, circulating fetuin-A (r = −0.37, p = 0.0004), but not adiponectin, associated with insulin secretion in subjects with impaired glucose tolerance.

Conclusions

We provide novel information that adiponectin and fetuin-A independently of each other associate with the diabetes risk. Furthermore, we suggest that they are involved in the development of type 2 diabetes via different mechanisms, possibly by mediating effects of their source tissues, expanded adipose tissue and nonalcoholic fatty liver.

Serum fetuin A concentration is elevated in children with non-alcoholic fatty liver disease

PURPOSE

To assess the serum fetuin A concentration as a potential marker of subclinical atherosclerosis in obese children with NAFLD.

MATERIAL/METHODS

A prospective analysis of 45 obese children initially diagnosed with liver pathology (elevated serum ALT activity and/or ultrasonographic liver brightness and/or hepatomegaly) was conducted. The diagnosis of NAFLD was established in the children with elevated serum ALT activity and liver steatosis on ultrasound examination. Viral hepatitis, autoimmune, metabolic liver diseases (Wilson disease, alpha-1-antitrypsin deficiency, cystic fibrosis) and drug and toxin-induced liver injury were excluded in all children. The degree of liver steatosis was graded according to Saverymuttu scale and the total liver lipids concentration was assessed using proton magnetic resonance spectroscopy ((1)H MRS).

RESULTS

Serum fetuin A concentration was significantly higher in examined children compared to the control group (n=30) (p=0.00002). Higher serum fetuin A concentration was also observed in children with NAFLD (n=19) in comparison to the controls (p=0.000026). Additionally, higher BMI values, waist circumferences, ALT and GGT activity, intensity of liver steatosis on ultrasound and total concentration of lipids in the liver in (1)H MRS were found in children with NAFLD compared to the rest of the examined obese patients (n=26). There was not found any correlation of the investigated glycoprotein with any other assessed parameters both in children with NAFLD and obese children without NAFLD.

CONCLUSION

Higher serum fetuin A concentration found in children with NAFLD compared to the control group support the hypothesis that atherosclerotic processes may develop faster in hepatopatic obese patients.

Effect of moderate alcohol consumption on fetuin-A levels in men and women: post-hoc analyses of three open-label randomized crossover trials

BACKGROUND

Fetuin-A, a liver-derived glycoprotein that impairs insulin-signalling, has emerged as a biomarker for diabetes risk. Although moderate alcohol consumption has been inversely associated with fetuin-A, data from clinical trials are lacking. Thus, we evaluated whether moderate alcohol consumption decreases circulating levels of fetuin-A.

METHODS

We analyzed data of three separate open-label, randomized, crossover trials: 1) 36 postmenopausal women consuming 250 ml white wine (25 g alcohol) or white grape juice daily for 6 weeks, 2) 24 premenopausal women consuming 660 ml beer (26 g alcohol) or alcohol-free beer daily for 3 weeks, and 3) 24 young men consuming 100 ml vodka (30 g alcohol) orange juice or only orange juice daily for 4 weeks. After each treatment period fasting blood samples were collected.

RESULTS

Circulating fetuin-A concentrations decreased in men after vodka consumption (Mean ± SEM: 441 ± 11 to 426 ± 11 μg/ml, p = 0.02), but not in women after wine (448 ± 17 to 437 ± 17 μg/ml, p = 0.16) or beer consumption (498 ± 15 to 492 ± 15 μg/ml, p = 0.48) compared to levels after each corresponding alcohol-free treatment. Post-hoc power analyses indicated that the statistical power to detect a similar effect as observed in men was 30% among the postmenopausal women and 31% among the premenopausal women.

CONCLUSIONS

In these randomized crossover trials, moderate alcohol consumption decreased fetuin-A in men but not in women. This sex-specific effect may be explained by the relatively short intervention periods or the low statistical power in the trials among women.

TRIALS REGISTRATION

ClinicalTrials.gov ID no's: NCT00285909, NCT00524550, NCT00918918.

Direct inhibitory effects of pioglitazone on hepatic fetuin-A expression

Fetuin-A, a circulating glycoprotein synthesized in the liver, is involved in insulin resistance and type 2 diabetes. However, regulation of fetuin-A synthesis has remained obscure. We previously reported that pioglitazone treatment significantly reduced serum fetuin-A levels in patients with type 2 diabetes. To clarify whether pioglitazone can directory inhibit hepatic fetuin-A synthesis, we investigated the effects of pioglitazone on fetuin-A expression both in vitro and in vivo. Pioglitazone treatment suppressed mRNA and protein expression of fetuin-A in Fao hepatoma cells. Interestingly, rosiglitazone but not metformin, also inhibited fetuin-A expression. In addition, GW 9662, an inhibitor of peroxisome proliferator-activated receptor (PPAR) γ, reversed pioglitazone-induced suppression of fetuin-A, suggesting that thiazolidinedione derivatives may have common characteristics with regard to fetuin-A suppression, possibly through PPARγactivation. Finally, oral administration of pioglitazone to mice for 8 weeks resulted in suppression of hepatic fetuin-A mRNA. These findings suggest that pioglitazone may partially ameliorate insulin resistance through its direct inhibitory effects on fetuin-A expression in the liver.

Preventive roles of swimming exercise and pioglitazone treatment on hepatic dysfunction in a rat model of metabolic syndrome

Pioglitazone (Pio) and swimming exercise (SE) are insulin sensitisers. This investigation was suggested because of the significant side effects associated with Pio treatment in metabolic syndrome (MetS). This study was, therefore, designed to investigate the preventive role of Pio treatment and SE in terms of efficiency and pathological changes in MetS in a rat model. Sixty male Sprague–Dawley rats were distributed equally among 6 groups: (i) control group (C), (ii) exercised control group (C+E), (iii) Pio-treated control group (C+Pio), (iv) group with MetS, (v) group with MetS treated with Pio (MetS+Pio), and (vi) exercised MetS group (MetS+E). Systolic blood pressure and heart rate were measured at the end of the experiments (16 weeks). Retro-orbital blood samples were used to determine the serum levels of glucose, insulin, lipids, gamma glutamyl transferase, alanine transaminase, aspartate transaminase, alkaline phosphatase, fetuin-A, and adiponectin. Semiquantitative reverse transcriptase – PCR insulin gene expression assays and hepatic histopathological examination were conducted. Swimming exercise significantly improved all of the aforementioned parameters, more so than the Pio treatment. In particular, the serum hepatic enzyme levels and hepatic histopathological changes were improved compared with the MetS group. These results suggested that swimming exercise might be an alternative physiological preventive tool against hepatic dysfunction to avoid the side effects associated with Pio treatment, and this could be demonstrated in a rat model of metabolic syndrome.

The relationship between serum fetuin-A, cystatin-C levels, and microalbuminuria in patients with metabolic syndrome

BACKGROUND

The metabolic syndrome, syndrome X, is a group of metabolic disorders in which insulin resistance plays a pivotal role. The MS is an important risk factor for subsequent development of type 2 diabetes and cardiovascular disease. Fetuin-A is a liver derived blood protein that acts as effective inhibitor of soft tissue calcification. Cystatin C is a useful marker in measuring glomerular filtration rate. Moreover, recently it has been suggested that cystatin C may be a potential biomarker for detecting microalbuminuria. Microalbuminuria (MA) is a strong indicator of morbidity related to cardiovascular disorders, and is currently considered a novel diagnostic criterion for MS. It has been also demonstrated that the increased serum fetuin-A levels is associated with several parameters of MS. In this study, we attempted to investigate the relationship between serum fetuin-A, cystatin-C levels and microalbuminuria in patients with MS.

METHODS

A total of 50 patients with MS and 25 control were included in this study. We defined MS by the NCEP criteria among nondiabetic outpatients. Patients with MS were further divided into two groups based on MA status. Overall 25 of the participants with MS did not have MA (group I), while the remaining 25 had MA (group II). None of the subjects in the healthy control group (group III) had laboratory findings supporting the presence of MA. The serum fetuin-A and cystatin-C levels were measured using ELISA.

RESULTS

Age, distributions of sex, BP and LDL cholesterol levels were similar among all groups. BMI, Waist/hip ratio, FBG, HOMA-IR, total cholesterol, trigliserid, CRP levels were significantly higher in group I and group II compared to control. In group II, the cystatin-C and fetuin levels were higher than control. While the cystatin-C levels were higher in group II compared to group I, the fetuin levels did not different. Morever, the fetuin A and cystatin-C concentrations were positively correlated with microalbuminuria (r = 0.26, p = 0.02; r = 0.50, p = 0.0001, respectively).

CONCLUSION

In our study, we found that MS patients with microalbuminuria had high levels of fetuin-A and cystatin-C. In conclusion, we suggest that determination of fetuin-A and cystatin C levels could be useful marker as an early indicator of renal injury in patients with MS.

Rapid improvement of hepatic steatosis after initiation of leptin substitution in a leptin-deficient girl

BACKGROUND

Leptin deficiency is associated with severe obesity and metabolic disturbances. Increased liver fat content has been reported in only one case beforehand, even though hepatic steatosis is a typical comorbidity of common obesity. It is also frequent in patients with lipodystrophy where it resolves under leptin therapy.

SUBJECT AND METHODS

In 2010, we reported a leptin-deficient patient with a novel homozygous mutation in the leptin gene and severe hepatic steatosis. We have now studied serum changes and changes in liver fat content during the substitution with recombinant methionyl human leptin.

RESULTS

After 23 weeks of leptin substitution, elevated transaminases, total cholesterol and low-density lipoprotein levels normalized. After 62 weeks, homeostasis model assessment of insulin resistance improved from 10.7 to 6.0 and body fat mass dropped from 50.2 to 37.8%. Liver fat content was drastically reduced from 49.7 to 9.4%. The first changes in liver fat content were detectable after 3 days of therapy.

CONCLUSION

Our patient showed a remarkable reduction of liver fat content during the treatment with recombinant methionyl human leptin. These changes occurred rapidly after initiation of the substitution, which implies that leptin has a direct effect on hepatic lipid metabolism in humans as it is seen in rodents.

Identification of nestin as a urinary biomarker for acute kidney injury

OBJECTIVES

Acute kidney injury (AKI) is a common complication in hospitalized patients and the incidence of AKI is rapidly increasing. Despite the advances in treatment of AKI, many patients still progress to end-stage renal disease and depend on dialysis. Therefore, early diagnosis and adequate treatment of AKI could improve prognosis.

METHODS

We established rat models of AKI induced by cisplatin nephrotoxicity and renal ischemia-reperfusion (I/R). Urine samples were collected, labeled with isobaric tags for relative and absolute quantification agents, and then subjected to nano-LC-MS/MS-based proteomic analysis. Results of the proteomic study were confirmed by Western blot. We also performed RNAi to silence nestin and investigate its role in renal I/R injury. We then validated its clinical application by studying urine nestin levels in AKI patients with cardiovascular surgeries.

RESULTS

Our proteomic analysis showed that fetuin-A, nestin, hamartin and T-kininogen were differentially expressed in the urine samples of rats after cisplatin or I/R treatment. Western blot confirmed the differential expression of these proteins in animal models and ELISA confirmed the differential expression of nestin in human urine samples. To explore the expression of nestin in the development of AKI, our results showed that nestin was primarily detected in the glomeruli and barely detected in tubular cells but increased in tubular cells during I/R- and cisplatin-induced AKI. The urine nestin-to-creatinine ratio increased earlier than serum creatinine in AKI patients with postcardiovascular surgeries. The role of nestin in AKI might be related to the p53 signaling pathway.

CONCLUSIONS

Thus, our results demonstrated that urinary nestin could be a urinary biomarker for patients with AKI and its role in AKI might be related to the p53 signaling pathway.

Higher fetuin-A, lower adiponectin and free leptin levels mediate effects of excess body weight on insulin resistance and risk for myelodysplastic syndrome

OBJECTIVE

Excess body weight has been implicated in the pathogenesis of myelodysplastic syndrome (MDS). We thus explored the role of serum fetuin-A reflecting ectopic hepatic fat deposition when storage capacity of adipocytes has been exceeded, free leptin reflecting overall fat mass and adiponectin reflecting visceral fat mass, all potential mediators of the effects of obesity on insulin resistance and, consequently, to MDS risk.

MATERIALS & METHODS

In a hospital-based case-control study, we studied 101 cases with incident, histologically confirmed primary MDS and 101 controls matched on gender, age and date of diagnosis, between 2004 and 2007. Serum fetuin-A, adiponectin, leptin, leptin receptor, free leptin and insulin were determined.

RESULTS

Higher serum fetuin-A, lower adiponectin and lower free leptin were all individually and independently associated with higher risk of MDS before and after controlling for matching and risk factors, such as age, gender, date of diagnosis, body mass index (BMI), family history of lymphohematopoietic cancer, smoking history and serum insulin. Interestingly, we have shown that these associations were prominent among overweight/obese individuals and persisted after controlling for BMI and serum insulin indicating that their effects are above and beyond insulinemia only.

CONCLUSION

Elevated serum fetuin-A but lower adiponectin and free leptin are associated with higher risk of MDS particularly among overweight/obese individuals. These findings suggest that the association between excessive weight gain and the risk of MDS could be mediated by fetuin-A, adiponectin and free leptin, which may have potential clinical and preventive implications.

Curcumin and diabetes: a systematic review

Turmeric (Curcuma longa), a rhizomatous herbaceous perennial plant of the ginger family, has been used for the treatment of diabetes in Ayurvedic and traditional Chinese medicine. The active component of turmeric, curcumin, has caught attention as a potential treatment for diabetes and its complications primarily because it is a relatively safe and inexpensive drug that reduces glycemia and hyperlipidemia in rodent models of diabetes. Here, we review the recent literature on the applications of curcumin for glycemia and diabetes-related liver disorders, adipocyte dysfunction, neuropathy, nephropathy, vascular diseases, pancreatic disorders, and other complications, and we also discuss its antioxidant and anti-inflammatory properties. The applications of additional curcuminoid compounds for diabetes prevention and treatment are also included in this paper. Finally, we mention the approaches that are currently being sought to generate a "super curcumin" through improvement of the bioavailability to bring this promising natural product to the forefront of diabetes therapeutics.

Lack of Association Between Variants within the AHSG , HCRT and NPY2R Genes and Anthropometrical Parameters in Czech Post-Monica Study

The aim of this study was to examine single nucleotide polymorphisms (SNPs) of candidate genes α 2-Heremans-Schmid glycoprotein ( AHSG , rs4917), Hypocretin ( HCRT , rs760282) and Neuropetide Y2 receptor (NPY2R , rs 1047214), which are known to have a potential effect on body mass index (BMI) and other indicators of obesity. A population study was performed in 2007/2008 on 2559 adults (1191 males and 1368 females) from the Czech post-MONICA project. The SNPs were examined using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. We did not find any significant association between the examined SNPs and BMI across the whole population. A significantly lower triglyceride level was found in the AHSG gene CC homozygotes compared to T allele carriers in the entire population ( p = 0.009). In conclusion, we are not able to confirm the hypothesis that polymorphisms within the AHSG , HCRT and NPY2R genes are major genetic determinants of BMI and plasma lipids in the Czech-Slavonic population.

Role of sex steroids, intrahepatic fat and liver enzymes in the association between SHBG and metabolic features

BACKGROUND

SHBG and liver enzymes levels are both associated with the risk of type 2 diabetes. However, the relationship between SHBG with liver enzymes and intrahepatic fat content remain poorly understood.

OBJECTIVE

To investigate whether SHBG is correlated with glucose and lipids levels and whether this association depends on fatty liver content, liver enzymes or sex hormone concentrations.

DESIGN AND PATIENTS

We studied 233 dysmetabolic men with measures of plasma SHBG, total testosterone, 17β-oestradiol, glucose, adiponectin, liver enzymes and hepatokines. Intrahepatic liver fat and visceral fat contents were measured by magnetic resonance imaging in 108 of these individuals.

RESULTS

After adjustment for age, SHBG concentration was inversely correlated with fasting glucose (βstandardized  = -0·21, P = 0·0007), HbA1c (βstandardized  = -0·27, P < 0·0001), triglycerides (βstandardized  = -0·19, P = 0·003) and positively correlated with HDL-Cholesterol (βstandardized  = 0·14, P = 0·03). These correlations persisted after adjustment for either total testosterone or 17β-oestradiol levels. SHBG was not related to either fetuin A or FGF 21 concentrations. The inverse association of SHBG with HbA1c and glycaemia was not altered after adjusting for liver markers but was no longer significant after adjustment for hepatic fat content.

CONCLUSION

The significant association between SHBG and fasting glycaemia, HbA1c and lipid levels in dysmetabolic men was not related to either sex hormones or markers of liver function, but was dependent on intrahepatic fat. This suggests that intrahepatic fat, but not alterations in liver function markers, may be involved in the association between SHBG and glucose and lipid metabolism.

The effects of caloric restriction on fetuin-A and cardiovascular risk factors in rats and humans: a randomized controlled trial

OBJECTIVES

The liver-secreted protein fetuin-A is associated with insulin resistance, metabolic syndrome, type 2 diabetes and atherosclerosis. We examined the effect of caloric restriction (CR) on fetuin-A levels and concomitant changes in hepatic steatosis and cardiovascular risk factors in rats and humans.

DESIGN AND SUBJECTS

We performed a randomized, controlled clinical trial to examine circulating fetuin-A levels and cardiovascular risk parameters including visceral fat area (VFA), atherogenic lipid profile, inflammatory markers, adipokines levels and brachial artery endothelial function in 76 overweight women with type 2 diabetes before and after 12 weeks of CR. In addition, the effects of CR on hepatic steatosis and fetuin-A mRNA expression were evaluated in Otuska Long Evans Tokushima Fatty (OLETF) rats, an animal model of obesity and type 2 diabetes.

RESULTS

Circulating fetuin-A levels were significantly decreased after 12 weeks of CR and were accompanied by improvements in VFA, blood pressure, glucose, lipid profiles and liver function. The CR group also showed a significant decrease in apolipoprotein B, leptin and insulin resistance compared to those in the control group, although endothelial function was not different. Multiple regression analysis showed that the changes in fetuin-A levels were independently associated with CR and changes in hsCRP and adiponectin (R² = 0·156). Moreover, CR significantly reduced hepatic steatosis and fetuin-A expression, as well as weight, glucose, total cholesterol and triglyceride levels, in OLETF rats.

CONCLUSION

Caloric restriction significantly reduced the hepatic expression of fetuin-A and its circulating levels and improved several cardiovascular risk factors in obese rats and humans with type 2 diabetes.

Fetuin-A mRNA expression is elevated in NASH compared with NAFL patients

Fetuin-A is a pro-inflammatory protein expressed by hepatocytes. Its course in morbidly obese patients with NAFLD (non-alcoholic fatty liver disease) following weight loss by BAS (bariatric surgery) has not been fully elucidated yet. In the present study, we prospectively examined the effects of weight loss on various metabolic factors at 4 weeks and 6 months after surgery. Blood and liver tissues were retrieved from 108 morbidly obese NAFLD patients before/during BAS, and 50 of these individuals met the criteria for NASH (non-alcoholic steatohepatitis). Fetuin-A expression was measured by qPCR (quantitative real-time PCR), Western blotting and immunohistochemistry. Hepatocyte apoptosis was quantified via M30 (caspase-cleaved cytokeratin-18 fragments). Plasma concentrations of adiponectin and fetuin-A were determined by ELISA. Serum-derived parameters were additionally taken at 4 weeks and 6 months post-operatively. In addition, primary human hepatocytes were treated with NEFA (non-esterified fatty acid) to investigate changes in fetuin-A. BMI (body mass index) decreased significantly from 53.0±1.1 to 36.4±1.9 kg/m2 in the NAFL group and from 53.3±1.1 to 37.6±1.2 kg/m2 in the NASH group (P<0.0001) at 6 months post-surgery. This was associated with diminishing M30 and M65 (total cytokeratin-18) levels over 6 months after surgery. Adiponectin levels increased continuously in NASH patients, whereas NAFL patients plateaued at 4 weeks post-operatively. Hepatic fetuin-A mRNA and protein expression was elevated before surgery-induced weight loss. However, plasma concentrations of fetuin-A increased signficantly in NASH patients 4 weeks post-operatively. Treatment of hepatocytes with NEFA led to up-regulation of fetuin-A expression. BAS probably has a beneficial effect on NAFLD, as indicated by reduced hepatocyte apoptosis and improved adipokine profiles. In addition, fetuin-A expression is more prominent in NASH.

Salsalate and adiponectin ameliorate hepatic steatosis by inhibition of the hepatokine fetuin-A

Fetuin-A was recently identified as a novel hepatokine which is associated with obesity, insulin resistance and non-alcoholic fatty liver disease. Salsalate, a prodrug of salicylate with an anti-inflammatory effect and lower side effect profile, significantly lowers glucose and triglyceride levels, and increased adiponectin concentrations in randomized clinical trials. In this study, we examined the effects and regulatory mechanisms of salsalate and full length-adiponectin (fAd) on fetuin-A expression, steatosis and lipid metabolism in palmitate-treated HepG2 cells. Incubation of hepatocytes with palmitate significantly increased fetuin-A and SREBP-1c expression which lead to steatosis and knock-down of fetuin-A by siRNA restored these changes. Salsalate significantly down-regulated palmitate-induced fetuin-A mRNA expression and secretion in a dose- and time-dependent manner. Inhibition of palmitate-induced fetuin-A by salsalate was mediated by AMPK-mediated reduction of NFκB activity, which was blocked by AMPK siRNA or an inhibitor of AMPK. Salsalate attenuated the excessive steatosis by palmitate through SREBP-1c regulation in hepatocytes. Furthermore, fAd also showed suppression of palmitate-induced fetuin-A through the AMPK pathway and improvement of steatosis accompanied by restoration of SREBP-1c, PAPR-α and CD36. In preliminary in vivo experiments, salsalate treatment inhibited high fat diet (HFD)-induced steatosis as well as fetuin-A mRNA and protein expression in SD rats. In conclusion, salsalate and fAd improved palmitate-induced steatosis and impairment of lipid metabolism in hepatocytes via fetuin-A inhibition through the AMPK-NFκB pathway.

Fetuin-A is linked to improved glucose tolerance after short-term exercise training in nonalcoholic fatty liver disease

Fetuin-A is synthesized in the liver and may be associated with nonalcoholic fatty liver disease (NAFLD) and type 2 diabetes. Lifestyle-induced weight loss reduces fetuin-A, but the effect of exercise alone is unknown. We determined the effect of short-term exercise training on plasma fetuin-A in 13 (50.5 ± 3.4 yr) obese adults (body mass index, 33.3 ± 0.9 kg/m(2)) with clinically diagnosed NAFLD. Subjects participated in 7 days of supervised exercise training (60 min/day at ∼85% maximum heart rate) and were instructed to maintain their normal caloric and macronutrient intake. Insulin resistance was assessed by an oral glucose tolerance test. Hepatic triglyceride content (HTGC) was determined by proton MRI. We used C2C12 skeletal muscle cells to examine the direct effect of fetuin-A on 2-deoxyglucose uptake, insulin signaling [phosphorylation of Akt and AS160 (pAkt and pAS160, respectively)], and glucose transporter-4 (GLUT-4) translocation. Insulin resistance was reduced by 29% (P < 0.05), and glucose area under the curve (AUC) was decreased by 13% (P < 0.01) after the 7 days of exercise. Furthermore, circulating fetuin-A was decreased by 11% (4.2 ± 03 vs. 3.6 ± 0.2 nM; P < 0.02), and this change correlated with reduced insulin resistance (r = 0.62; P < 0.04) and glucose AUC (r = 0.58; P < 0.04). Importantly, the exercise program did not change body weight (P = 0.12), HTGC (P = 0.73), or aerobic capacity (P = 0.14). In vitro experiments revealed that fetuin-A decreased skeletal muscle glucose uptake by downregulating pAkt and pAS160 and subsequent GLUT-4 translocation to the plasma membrane. Together, our findings highlight a role for fetuin-A in skeletal muscle insulin resistance and suggest that part of the exercise-induced improvement in glucose tolerance in patients with NAFLD may be due to lowering fetuin-A.

Association of AHSG gene polymorphisms with ischemic stroke in a Han Chinese population

Previous studies have shown associations of fetuin-A (alpha2-Heremans-Schmid glycoprotein, AHSG) with various disorders, including insulin resistance, type 2 diabetes mellitus, metabolic syndrome, and atherosclerosis. In this study, genotype and allele frequencies of the rs4918 SNP in the AHSG gene were examined in 380 patients with ischemic stroke and 350 healthy controls from a Northern Han Chinese population via the PCR-RFLP technique. Frequencies of the GG genotype and the G allele in AHSG (rs4918) were significantly higher in patients with ischemic stroke or atherosclerotic cerebral infarction than those in the control group (P < 0.05). Logistic regression analysis demonstrated the significance of rs4918 in these patients, after adjustment for confounding factors (P < 0.05). These findings suggest that rs4918 SNPs of the AHSG gene are associated with a risk for ischemic stroke in a Northern Han Chinese population.