Serum fetuin-A associates with type 2 diabetes and insulin resistance in Chinese adults

Rethinking Mitral Annular Calcification and Its Clinical Significance: From Passive Process to Active Pathology

BACKGROUND

Mitral annulus calcification is a chronic degenerative condition affecting the fibrous base of the mitral valve. Historically viewed as an age-related phenomenon, recent studies suggest it is driven by active mechanisms involving systemic inflammation, hemodynamic stress, abnormal calcium-phosphorus metabolism, and lipid accumulation. Despite often being asymptomatic and incidentally detected, its clinical relevance stems from its strong association with increased cardiovascular disease risk, higher cardiovascular mortality, and elevated overall mortality.

METHODS

This article investigates the complexities and controversies surrounding mitral annular calcification as a potential embolic source, focusing on its diagnosis, its relationship with systemic inflammation, and its links to metabolic and chronic disorders.

RESULTS

The findings highlight that mitral annular calcification is not merely a passive marker of aging but an active indicator of atherosclerotic burden with significant implications for cardiovascular health.

CONCLUSION

Mitral annulus calcification should be recognized as an important factor in cardiovascular risk assessment, offering insight into systemic inflammatory processes and metabolic dysregulation.

Association of pro-inflammatory cytokines, adipokines and hepatokine with incident diabetes in India: a nested case-control study within CARRS cohort

AIMS

To study the association of pro-inflammatory markers with incident diabetes in India.

METHODS

We did a nested case-control study within the CARRS (Centre for Ardiometabolic Risk Reduction in South Asia) cohort. Of the 5739 diabetes-free individuals at the baseline, 216 participants with incident diabetes and 432 age-, gender- and city-matched controls at 2-year follow-up were included. We measured high sensitive C-reactive protein (hsCRP), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), monocyte chemoattractant protein-1 ( MCP-1), adiponectin, leptin and fetuin-A in the stored baseline blood samples. We did multivariate conditional logistic regression to estimate association of inflammatory markers (as quartiles) and incident diabetes. Covariates were baseline fasting plasma glucose (FPG) and lipids, body mass index (BMI), family history of diabetes, smoking and alcohol use.

RESULTS

Baseline hsCRP and TNF-α were higher, and IL-6 and adiponectin were lower among cases vs. controls. In multivariate conditional logistic regression models, only quartile-3 (odds ratio [OR]: 2.96 [95% CI:1.39, 6.30]) and quartile-4 (OR: 2.58 [95% CI: 1.15, 5.79]) of TNF-α and quartile-4 of MCP-1 (OR: 2.55 [95% CI: 1.06, 6.16]) were positively associated with diabetes after adjusting for baseline FPG and BMI. These associations did not remain after adjusting for family history. High level (quartile-4) of IL-6 was negatively associated with diabetes after adjusting for all factors (OR: 0.18 [95% CI: 0.06, 0.55]).

CONCLUSIONS

Higher TNF-α and MCP-1 levels and lower IL-6 were associated with higher risk of developing diabetes. Better understanding and potential methods of addressing these biomarkers, especially in relation to family history, are needed to address diabetes in South Asians.

Evaluation of Fetuin-A level in diabetic retinopathy

Background

Diabetic retinopathy (DR) is a micro-vascular consequence of diabetes mellitus (DM) that manifests clinically as retinal ischemia, neovascularization, altered retinal permeability, and macular edema. In the adult population, DR is now considered a leading cause of blindness. Fetuin-A is a multifunctional glycoprotein that, because of its dual role in insulin resistance and angiogenesis, could be an early trigger of DR pathogenesis.

Objective

This study aimed to evaluate the level of Fetuin-A in diabetic patients with and without retinopathy and demonstrate if it could be used as an early indicator of DR.

Patients and methods

A case–control study enrolled 45 participants selected from Al-Zahraa University Hospital, between March 2021 and October 2021, they were divided into three groups: Group 1: healthy control group (n=15); Group 2: type 2 diabetic patients without DR (n=15); and Group 3: type 2 diabetic patients with DR (n=15). All groups were age- and sex-matched and were investigated by enzyme-linked immunosorbent assay (ELISA) to evaluate serum level of Fetuin-A.

Results

There was a highly significant difference of FBG, 2HPP, and HbA1c between the studied groups (p< 0.001), while there was no significant difference between the three studied groups regarding Fetuin-A. There were no significant correlation between Fetuin-A, glycemic parameters, and diabetic duration in Groups 2 and 3.

Conclusion

Fetuin-A has no significant role in the pathogenesis of diabetic retinopathy.

Liver Fetuin-A at Initiation of Insulin Resistance

Hepatokines (liver secreted proteins with possible distant action) are emerging potential players in insulin resistance in type 2 diabetic patients. Here, we explored the effect of a high-fat diet on the expression of fetuin-A, one of those candidate liver proteins, and its relationship with liver macrophage activation. Mice were fed a normal diet or a high-fat diet for 3 days, known to initiate steatosis and liver insulin resistance. A preventive liver macrophage depletion was obtained by intravenous injection of clodronate-loaded liposomes. The mRNA and protein expression of fetuin-A was evaluated by qPCR, Western blot and immunofluorescence on different insulin-sensitive tissues (liver, adipose tissue, and muscle). Short-term high-fat diet-induced steatosis, liver macrophage activation, and hepatic insulin resistance together with a significantly increased expression of liver AHSG (α2-HS glycoprotein/fetuin-A) mRNA and serum fetuin-A concentration. On immunofluorescence, fetuin-A was mostly expressed in centrilobular hepatocytes. This increase in fetuin-A under high-fat diet was not evidenced in other peripheral insulin-sensitive tissues (skeletal muscle and adipose tissue). The mRNA expression of α2-HS glycoprotein was 800 times higher within the liver compared with the adipose tissue or the muscle. Liver macrophage depletion that significantly ameliorated insulin sensitivity was associated with a significant decrease in α2-HS glycoprotein mRNA expression. In conclusion, this study demonstrated liver fetuin-A overexpression at the initiation of high-fat diet feeding, concurrent with hepatic steatosis and insulin resistance. Targeting liver macrophages in this setting reduced liver α2-HS glycoprotein expression suggesting that fetuin-A acts as an hepatokine with proinsulin resistance effects.

The structure, biosynthesis, and biological roles of fetuin-A: A review

Fetuin-A is a heterodimeric plasma glycoprotein containing an A-chain of 282 amino acids and a B-chain of 27 amino acid residues linked by a single inter-disulfide bond. It is predominantly expressed in embryonic cells and adult hepatocytes, and to a lesser extent in adipocytes and monocytes. Fetuin-A binds with a plethora of receptors and exhibits multifaceted physiological and pathological functions. It is involved in the regulation of calcium metabolism, osteogenesis, and the insulin signaling pathway. It also acts as an ectopic calcification inhibitor, protease inhibitor, inflammatory mediator, anti-inflammatory partner, atherogenic factor, and adipogenic factor, among other several moonlighting functions. Fetuin-A has also been demonstrated to play a crucial role in the pathogenesis of several disorders. This review mainly focuses on the structure, synthesis, and biological roles of fetuin-A. Information was gathered manually from various journals via electronic searches using PubMed, Google Scholar, HINARI, and Cochrane Library from inception to 2022. Studies written in English and cohort, case-control, cross-sectional, or experimental studies were considered in the review, otherwise excluded.

Hepatokines Fetuin-A and Fetuin-B status in obese Saudi patient with diabetes mellitus type 2

The present study aims to investigate the association of the serum levels of Fetuin-A and Fetuin-B with type 2 diabetes mellitus (T2DM) in obese Saudi patients and explore the mechanism that links obesity and T2DM in Saudi patients. In this study, a total of 240 adult Saudis (116 men and 124 women) in the age group of 42.7±11.6 years were divided into three groups based on fasting blood glucose (FBG) levels: controls, T2DM and prediabetic. The levels of FBG, lipid profile and serum insulin were measured. Enzyme-linked immunosorbent assay (ELISA) was done to measure Fetuin-A, Fetuin-B and C-reactive protein (CRP). The results show that participants of the prediabetic and T2DM groups had significantly higher body mass index (BMI) values and elevated blood pressure (BP), FBG, total cholesterol (TC), triglyceride (TG), insulin, homeostatic model assessment-IR (HOMA-IR) and homeostatic model assessment-β (HOMA-β) as compared to the control group (P<0.001). The T2DM group participants exhibited significantly higher BMI, BP, FBG, TG, insulin, HOMA-IR and HOMA-β as compared to the prediabetic group participants (P<0.001). The serum levels of high-density lipoprotein-cholesterol (HDL-C) and low-density lipoprotein-cholesterol (LDL-C) were not significantly different among the three tested groups. The serum concentrations of CRP, Fetuin-A and Fetuin-B were slightly higher in T2DM patients as compared to the control group, but the difference failed to reach statistical significance (P>0.05). When results were segregated according to gender, FBG and HDL-C were significantly elevated (P=0.043 and P=0.002, respectively) in T2DM women (12.6±3.6 mmol/l and 1.0±0.3 mmol/l, respectively) compared to T2DM men (11.0±3.3 mmol/l and 0.86±0.2 mmol/l, respectively). However, the diastolic BP and waist-hip ratio (WHR) were significantly increased (P=0.010 and P=0.006, respectively) in T2DM men. The BMI and TC and all other measured parameters were similar between the two genders. Fetuin-A was significantly and positively associated with insulin levels (R=0.19, P=0.05), HOMA-IR (R=0.25, P=0.01) and TG (R=0.20, P=0.01) among overall participants of this study. The T2DM participants exhibited a significantly positive correlation with body weight. Fetuin-A was significantly and positively correlated with Fetuin-B in prediabetic participants, but this relation was not observed in the T2DM participants. Fetuin-B correlated inversely (P<005) with systolic BP (R=-0.20, P=0.01) and diastolic BP (R=-0.18, P=0.05). Interestingly, a strong inverse correlation was observed between Fetuin-B and TG in overall participants (R=-0.21, P=0.01) and specifically in T2DM women (R=-0.41, P=0.01). In conclusion, our study did not find a significant association of Fetuin-A or Fetuin-B levels in serum with T2DM. However, our results suggest that Fetuin-A may influence insulin resistance and serum Fetuin-B concentrations were inversely associated with TG in the general adult Saudi population.

AGEs-Induced Calcification and Apoptosis in Human Vascular Smooth Muscle Cells Is Reversed by Inhibition of Autophagy

Vascular calcification (VC) in macrovascular and peripheral blood vessels is one of the main factors leading to diabetes mellitus (DM) and death. Apart from the induction of vascular calcification, advanced glycation end products (AGEs) have also been reported to modulate autophagy and apoptosis in DM. Autophagy plays a role in maintaining the stabilization of the external and internal microenvironment. This process is vital for regulating arteriosclerosis. However, the internal mechanisms of this pathogenic process are still unclear. Besides, the relationship among autophagy, apoptosis, and calcification in HASMCs upon AGEs exposure has not been reported in detail. In this study, we established a calcification model of SMC through the intervention of AGEs. It was found that the calcification was upregulated in AGEs treated HASMCs when autophagy and apoptosis were activated. In the country, AGEs-activated calcification and apoptosis were suppressed in Atg7 knockout cells or pretreated with wortmannin (WM), an autophagy inhibitor. These results provide new insights to conduct further investigations on the potential clinical applications for autophagy inhibitors in the treatment of diabetes-related vascular calcification.

Fetuin-A as a Marker of Insulin Resistance

Fetuin–A is a glycoprotein which helps in the regulation of metabolism. It is an early marker of insulin resistance (IR). The aim of this study was to evaluate the role of Fetuin–A as a predictive biomarker in cases of newly detected type 2 diabetes (NDD). The study involved 60 NDD and 60 Normal Healthy Controls (NHC). All the demographics and anthropological characteristics were noted. Fasting blood samples were drawn and various biochemical parameters were analyzed. The homeostatic model assessment of insulin resistance (HOMA-IR) and the quantitative insulin sensitivity check index (QUICKI) score was calculated. Chisquare, student T-test and Mann Whitney U tests were employed to associate and compare the mean and median between the NDD and NHC groups. Pearson's and Spearman’s correlation analysis were employed to examine the relationship of Fetuin–A levels with parametric and nonparametric variables. The independent predictors of Fetuin–A was determined by employing multiple forward linear regression. Fetuin–A was significantly high in NDD compared to NHC (1323 vs. 306.98 mcg/mL; p<0.001). Majority of NDD patients demonstrated IR based on the HOMA-IR (88.33% vs. 66.67%) and QUICKI score (96.67% vs. 85%). The multiple linear regression analysis showed that systolic blood pressure, age and QUICKI score were independently associated with Fetuin–A (p value <0.01). Fetuin–A may be used as a biomarker to detect NDD. Therefore, early detection of Fetuin–A levels in NDD gives an opportunity for suitable patient management.

Analysis of an Indian diabetes prevention programme on association of adipokines and a hepatokine with incident diabetes

To study the association and possible predictive role of visfatin, resistin, fetuin-A and chemerin with incident type 2 diabetes (T2DM) among Asian Indians with prediabetes. Their association with insulin resistance, β-cell function, glycaemia and anthropometry were also studied. This is a nested case-control study of a large 2-year prospective prevention trial in persons at high risk of developing T2DM. Baseline HbA1c values between 6.0% (42 mmol/mol) and 6.2% (44 mmol/mol) were chosen for this analysis (n = 144). At follow-up, persons with incident T2DM (HbA1c ≥ 6.5%, 48 mmol/mol) were grouped as cases (n = 72) and those reverted to normoglycaemia, (HbA1c < 5.7% (39 mmol/mol) as controls (n = 72). Insulin resistance showed the strongest association with incident T2DM ((Odds Ratio (OR): 23.22 [95%CI 6.36-84.77]; p < 0.0001). Baseline visfatin (OR: 6.56 [95%CI 2.21-19.5]; p < 0.001) and fetuin-A (OR: 1.01 [95%CI (1.01-1.04)]; p < 0.0001) independently contributed to the conversion of prediabetes to T2DM. The contribution was significantly higher when their elevated levels coexisted (OR: 12.63 [95%CI 3.57-44.63]; p < 0.0001). The area under the curve was 0.77 ± SE 0.4 (95%CI 0.69-0.85) and 0.80 ± SE 0.04 (95%CI 0.73-0.88) for visfatin (median 17.7 ng/ml, sensitivity and specificity: 75%, p < 0.0001) and fetuin-A (mean 236.2 µg/ml, sensitivity: 71%, specificity: 75%, p < 0.0001) respectively. Higher baseline visfatin and fetuin-A concentrations are strongly associated with incident T2DM and are predictive of future diabetes.

Fetuin-B, a potential link of liver-adipose tissue cross talk during diet-induced weight loss-weight maintenance

Background/objectives

Numerous hepatokines are involved in inter-organ cross talk regulating tissue-specific insulin sensitivity. Adipose tissue lipolysis represents a crucial element of adipose insulin sensitivity and is substantially involved in long-term body weight regulation after dietary weight loss. Thus, we aimed to analyze the impact of the hepatokine Fetuin-B in the context of weight loss induced short- and long-term modulation of adipose insulin sensitivity.

Subjects/methods

143 subjects (age > 18; BMI ≥ 27 kg/m²) were analyzed before (T-3) and after (T0) a standardized 12-week dietary weight reduction program. Afterward, subjects were randomized to a 12-month lifestyle intervention or a control group. After 12 months (T12) no further intervention was performed until 6 months later (T18) (Maintain-Adults trial). Tissue-specific insulin sensitivity was estimated by HOMA-IR (predominantly liver), ISI_Clamp (predominantly skeletal muscle), and free fatty acid suppression during hyperinsulinemic-euglycemic clamp (FFA_Supp) (predominantly adipose tissue). Fetuin-B was measured at all concomitant time points.

Results

Circulating Fetuin-B levels correlated significantly with estimates of obesity, hepatic steatosis as well as HOMA-IR, ISI_Clamp, FFA_Supp at baseline. Fetuin-B decreased during dietary weight loss (4.2 (3.5–4.9) vs. 3.8 (3.2–4.6) µg/ml; p = 2.1 × 10⁻⁵). This change was associated with concomitant improvement of HOMA-IR (r = 0.222; p = 0.008) and FFA_Supp (r = −0.210; p = 0.013), suggesting a particular relationship to hepatic and adipose tissue insulin sensitivity. Weight loss induced improvements of insulin resistance were almost completely preserved until months 12 and 18 and most interestingly, the short and long-term improvement of FFA_Supp was partially predicted by baseline level of Fetuin-B.

Conclusions

Our data suggest that Fetuin-B might be a potential mediator of liver-adipose cross talk involved in short- and long-term regulation of adipose insulin sensitivity, especially in the context of diet-induced weight changes.

Trial registration

ClinicalTrials.gov number: NCT00850629, https://clinicaltrials.gov/ct2/show/NCT00850629, date of registration: February 25, 2009.

Cirrhosis and insulin resistance: current knowledge, pathophysiological mechanisms, complications and potential treatments

End-stage chronic liver diseases are often associated with insulin resistance (IR) and diabetes mellitus (DM). Indeed, to quantify insulin sensitivity the euglycemic clamp technique was utilized, allowing the following to be stated: in small groups of patients, an IR in almost all cirrhotic patients can be observed, compared with a control group. Additionally, it has been demonstrated that IR in cirrhosis is linked to a decreased peripheral (muscle) glucose uptake rather than an increased liver glucose production. The homoeostasis model of IR (HOMA-IR) technique, devised only later, was then exploited to assess this same phenomenon in a larger sample population. The research established that even in patients with preserved liver function, cirrhosis is associated with significant alterations in glucose homoeostasis levels. The purpose of the present paper is to present the current research around the affiliation of cirrhosis and IR, discuss potential mechanisms explaining the association between cirrhosis and IR (i.e. endocrine perturbation, liver inflammation, altered muscle mass and composition, altered gut microbiota and permeability), complications that can arise as well as treatment options, through a critical review of the literature surrounding this subject. This research will also be investigating the beneficial impact, if there is any, of identifying and curing IR in patients with cirrhosis.

Effects of fetuin-A with diverse functions and multiple mechanisms on human health

Fetuin-A (Alfa 2-Heremans-Schmid) is a glycoprotein that is mainly synthesized by hepatocytes and then released into the bloodstream. While fetuin-A, a multifunctional protein, has inhibitory effects on health in the processes of calcification, mineralization, coronary artery calcification (CAC), and kidney stone formation by various mechanisms, it has such stimulatory effects as obesity, diabetes, and tumor progression processes. Fetuin-A produces these effects on the organism mainly by playing a role in the secretion levels of some inflammatory cytokines and exosomes, preventing unwanted calcification, inhibiting the autophosphorylation of tyrosine kinase, suppressing the release of adiponectin and peroxisome proliferator-activated receptor-γ (PPARγ), activating the toll-like receptor 4 (TLR-4), triggering the phosphatidylinositol 3 (PI3) kinase/Akt signaling pathway and cell proliferation, and mimicking the transforming growth factor-beta (TGF-β) receptor. In the present review, fetuin-A was examined in a wide perspective from the structure and release of fetuin-A to its effects on health.

Inflammatory markers in children and adolescents with type 2 diabetes mellitus

This review examines the potential relationship between serum inflammation markers and type 2 diabetes mellitus (T2DM). Inflammation markers have been proposed as prognostic markers for the development of T2DM and its complications. Furthermore, modulation of the inflammatory process may offer future treatment strategies for T2DM. This review focuses on children and adolescents because there is usually little, if any, complications associated with other disease processes, use of medications, or active tobacco smoking. Furthermore, β-cell failure in young age cannot be solely explained by aging and exhaustion of β-cells due to insulin resistance. Pediatric studies have demonstrated that pro-inflammatory cytokines TNF-α, IL-6, IL-1β, IFNγ, PEDF, and fetuin A were increased in insulin resistance, while the anti-inflammatory cytokines adiponectin and omentin were decreased. Furthermore, TNF-α, fetuin A, FGF-21 were altered in obese children with T2DM suggesting a direct involvement in β-cell failure. Future studies focusing on children and adolescents may facilitate our understanding of T2DM as an inflammatory disease process.

Fetuin-A levels are increased in the adipose tissue of diabetic obese humans but not in circulation

Background

The hepatokine fetuin-A is linked to obesity and type 2 diabetes, but its presence and expression in adipose tissue remain unclear. In this study, we aimed to assess the circulating levels of fetuin-A and its expression in subcutaneous adipose tissue (SAT) from diabetic and non-diabetic obese subjects and their modulation by exercise.

Methods

SAT and blood were obtained from adults obese (diabetic, n=118 and non-diabetic, n=166) before and after a 3-month exercise program (diabetic, n=40 and non-diabetic, n=36, respectively). Plasma fetuin-A was assayed using ELISA. The presence and expression of fetuin-A in SAT, peripheral blood mononuclear cells (PBMCs) and cell lines (3T3-L1, THP-1, HepG2, RAW 264.7) were analysed using confocal microscopy, immunoblotting and qRT-PCR.

Results

Plasma fetuin-A level did not significantly differ between diabetic and non-diabetic obese subjects. However, when the non-diabetic group was divided into metabolically healthy and unhealthy phenotypes, significantly higher fetuin-A level was observed in the unhealthy sub-group. Circulating fetuin-A was mainly associated with glycaemic markers. In SAT, fetuin-A protein level was significantly higher in the diabetic obese subjects but its mRNA was not detected. Similarly, fetuin-A protein was detected in PBMCs, but its mRNA was not. In line with this, the use of various cell lines and culture media indicated that the presence of fetuin-A in SAT and PBMCs was due to its uptake from circulation rather than its endogenous expression. Finally, physical exercise decreased fetuin-A levels in both plasma and SAT in both groups.

Conclusions

Fetuin-A levels increased in association with diabetes in SAT but not in circulation in the obese subjects. Moreover, physical exercise decreased fetuin-A level. Fetuin-A potentially acts as a hepatokine taken up by other tissues, such as adipose tissue.

Electronic supplementary material

The online version of this article (10.1186/s12944-018-0919-x) contains supplementary material, which is available to authorized users.

Serum levels of fetuin-A are negatively associated with log transformation levels of thyroid-stimulating hormone in patients with hyperthyroidism or euthyroidism: An observational study at a medical center in Taiwan

Fetuin-A is a protein with various biological functions. It plays a role in insulin resistance and arterial calcium deposition. Thyroid dysfunction may affect energy expenditure, glucose metabolism, and the risk of cardiovascular diseases. In the present study, we compared the serum fetuin-A concentrations in hyperthyroid patients with those in euthyroid patients.We recruited 30 newly-diagnosed hyperthyroid patients (the HY group) and treated them with anti-thyroid regimens as clinically indicated. We recruited 30 euthyroid individuals (the EU group) as controls. We compared laboratory parameters at the baseline and at 6 months. We then determined the associations between the levels of fetuin-A and free thyroxine (fT4), thyroid-stimulating hormone (TSH), or log transformation of TSH (logTSH).At the baseline, the HY patients had significantly higher serum fetuin-A levels than the EU patients (median [Q1, Q3]: 735.4 [537.9, 843.4] ng/mL vs 561.1[449.2, 670.5] ng/mL, P = .010). At 6 months, the serum fetuin-A levels of the HY patients decreased but were still higher than those of the EU patients (698.4 [627.6, 924.3] ng/mL vs 616.5 [498.2, 727.7] ng/mL, P = .002). At baseline, the serum levels of fetuin-A were negatively associated with logTSH (β = -53.79, P = .010). At 6 months, the levels of fetuin-A were positively associated with fT4 (β = 86.91, P = .039), and negatively associated with logTSH (β = -104.28, P < .001). Changes to the levels of fetuin-A within 6 months were negatively associated with changes to logTSH (β = -57.80, P = .019). The negative associations between fetuin-A levels and logTSH at baseline and at 6 months, and the changes during the 6 months remained significant after adjustment for sex and age (β = -51.72, P = .016; β = -103.11, P < .001; and β = -59.36, P = .020, respectively).The patients with hyperthyroidism had higher serum fetuin-A levels than the patients with euthyroidism. In patients with hyperthyroidism, the serum fetuin-A concentrations decreased after the anti-thyroid treatment. In the present study, serum fetuin-A concentrations were negatively associated with logTSH.

Inflammation Markers in Type 2 Diabetes and the Metabolic Syndrome in the Pediatric Population

PURPOSE OF REVIEW

Chronic inflammation, adipokines, and hepatokines have been identified as basis of insulin resistance and β cell failure in animal models. We present our current knowledge concerning the potential relationship between these cytokines, inflammation, metabolic syndrome (MetS), and type 2 diabetes mellitus (T2DM) in the pediatric population.

RECENT FINDINGS

Pro-inflammatory cytokines related to insulin resistance and MetS in children are tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, IL-1β, interferon gamma, pigment epithelium-derived factor, chemerin, vaspin, and fetuin A. Anti-inflammatory cytokines associated with insulin resistance and MetS in children are leptin, adiponectin, omentin, fibroblast growth factor (FGF)-21, osteocalcin, and irisin. These anti-inflammatory cytokines are decreased (adiponectin, omentin, and osteocalcin) or increased (leptin, FGF-21, and irisin) in obesity suggesting a resistance state. TNF-α, fetuin A, and FGF-21 are altered in obese children with T2DM suggesting an involvement in β cell failure. These cytokines, adipokines, and hepatokines may be able to predict development of MetS and T2DM and have a potential therapeutic target ameliorating insulin resistance.

Relationship of Serum Fetuin A with Metabolic and Clinical Parameters in German Children and Adolescents with Type 1 Diabetes

BACKGROUND AND AIM

The hepatokine fetuin A is upregulated in the metabolic syndrome and in type 2 diabetes (T2D), while its role in adolescent type 1 diabetes (T1D) is unclear. We assessed the relationship between circulating fetuin A levels and metabolic control, comorbidities, and complications in adolescent T1D patients.

METHODS

We studied the relationship between serum fetuin A and clinical diabetes-related data from the DPV registry (Diabetes-Pa-tienten-Verlaufsdokumentation) in 172 adolescent T1D patients with early-onset (<5 years) long-standing (>10 years) T1D. Fetuin A levels were further compared between adolescent T1D and T2D patients.

RESULTS

Serum fetuin A levels in T1D patients (mean 0.267 ± 0.043 g/L) did not correlate with age, diabetes duration, gender, body mass index (BMI), glycated hemoglobin, serum lipid levels, blood pressure, celiac or thyroid disease, nephropathy, or retinopathy. An association of fetuin A levels with insulin requirements was only evident within the subgroup of overweight T1D patients (rs = 0.439, p = 0.028, n = 25, BMI >90th percentile), disappearing after adjustment for multiple testing. Adolescent T1D patients showed distinctly lower fetuin A levels than patients with T2D (p ≤ 0.001).

CONCLUSION

Overall, we did not observe a clinically relevant association of fetuin A levels with surrogate parameters for insulin sensitivity in our juvenile T1D cohort. A correlation with insulin requirements was detectable in overweight patients only. We hypothesize that multiple factors, such as obesity, puberty, inadequate metabolic control, and hepatic steatosis, have to add up before a clinically relevant effect of fetuin A on insulin sensitivity becomes evident.

Does bariatric surgery influence plasma levels of fetuin-A and leukocyte cell-derived chemotaxin-2 in patients with type 2 diabetes mellitus?

Background

Fetuin-A and leukocyte cell-derived chemotaxin-2 (LECT-2) are liver-derived proteins. Fetuin-A is an independent risk factor for type 2 diabetes (T2D) and obese patients with T2D have higher plasma fetuin-A levels than those without T2D. LECT-2 has positive correlation with the severity of both obesity and insulin resistance. The changes in plasma fetuin-A are not consistent after bariatric surgery and no studies have investigated the changes in LECT-2 on the obese patients with T2D after bariatric surgery.

Methods

Overall, 18 patients undergoing gastric bypass (GB) and 16 patients undergoing sleeve gastrectomy (SG) were enrolled. The fasting plasma fetuin-A and LECT-2 levels were measured at baseline, one week, three months, and one year after surgery.

Results

Both the GB and SG groups significantly decreased the body mass index (BMI), waist-to-hip ratio, a body shape index; the triglyceride, fasting blood sugar (FBS), hemoglobin A1c, C-peptide levels; and homeostatic model assessment (HOMA-IR) one year after surgery. The SG group showed a decreasing trend in plasma fetuin-A levels one year after SG surgery. There are no significant changes in LECT-2 one year after either GB or SG. Fetuin-A had a near significant negative relationship with insulin (P = 0.056) and HOMA-IR (P = 0.050) in the SG group. Changes in fetuin-A had a significant positive relationship with changes in BMI (P = 0.031) and waist-to-hip ratio (P = 0.031) in the GB group and had a near significant positive correlation with FBS (P = 0.051) in the SG group.

Discussion

Neither GB nor SG modifies plasma levels of plasma fetuin-A or LECT-2 in T2D patients after surgery. The changes in plasma fetuin-A have a positive correlation with those of the BMI and waist-to-hip ratio 12 months after GB.

Prolactin improves hepatic steatosis via CD36 pathway

BACKGROUND & AIMS

Prolactin (PRL) is a multifunctional polypeptide with effects on metabolism, however, little is known about its effect on hepatic steatosis and lipid metabolism. Herein, we aimed to assess the role of PRL in the development of non-alcoholic fatty liver disease (NAFLD).

METHODS

The serum PRL levels of 456 patients with NAFLD, 403 controls without NAFLD diagnosed by ultrasound, and 85 individuals with liver histology obtained during metabolic surgery (44 female and 30 male patients with NAFLD and 11 age-matched non-NAFLD female individuals) were evaluated. The expression of the gene encoding the prolactin receptor (PRLR) and signalling molecules involved in hepatic lipid metabolism were evaluated in human liver and HepG2 cells. The effects of overexpression of PRLR or fatty acid translocase (FAT)/CD36 or knockdown of PRLR on hepatic lipid metabolism were tested in free fatty acid (FFA)-treated HepG2 cells.

RESULTS

Circulating PRL levels were lower in individuals with ultrasound-diagnosed NAFLD (men: 7.9 [range, 5.9-10.3] µg/L; women: 8.7 [range, 6.1-12.4] µg/L) than those with non-NAFLD (men: 9.1 [range, 6.8-13.0] µg/L, p = 0.002; women: 11.6 [range, 8.2-16.1] µg/L, p <0.001). PRL levels in patients with biopsy-proven severe hepatic steatosis were lower compared with those with mild-to-moderate hepatic steatosis in both men (8.3 [range, 5.4-9.5] µg/L vs. 9.7 [range, 7.1-12.3] µg/L, p = 0.031) and women (8.5 [range, 4.2-10.6] µg/L vs. 9.8 [range, 8.2-15.7] µg/L, p = 0.027). Furthermore, hepatic PRLR gene expression was significantly reduced in patients with NAFLD and negatively correlated with CD36 gene expression. In FFA-induced HepG2 cells, PRL treatment or PRLR overexpression significantly reduced the expression of CD36 and lipid content, effects that were abrogated after silencing of PRLR. Furthermore, overexpression of CD36 significantly reduced the PRL-mediated improvement in lipid content.

CONCLUSIONS

Our results reveal a novel association between the central nervous system and the liver, whereby PRL/PRLR improved hepatic lipid accumulation via the CD36 pathway.

LAY SUMMARY

Our clinical study suggests a negative association between prolactin (PRL)/prolactin receptor (PRLR) and the presence of non-alcoholic fatty liver disease (NAFLD). Using cell experiments, we found that PRL ameliorates hepatic steatosis via the hepatic PRLR and fatty acid translocase (FAT)/CD36, a key transporter of free fatty acid uptake in liver. Our findings suggest a novel approach to improving NAFLD using PRL and PRLR. Clinical trial number: NCT03296605.

The association between circulating fetuin-A levels and type 2 diabetes mellitus risk: systematic review and meta-analysis of observational studies

BACKGROUND AND OBJECTIVE

Fetuin-A is a liver-derived circulating protein that is associated with insulin resistance and diabetes. The objective of this systematic review and meta-analysis of published observational studies was to investigate mean levels of fetuin-A in T2D patients and the relationship between blood fetuin-A levels and T2D risk.

MATERIALS AND METHODS

PubMed, Embase, Google Scholar, Web of Science, and The Cochrane Library were systematically searched for potential relevant studies up to 1 December 2016. Natural logarithm-transformed estimate risks, standard mean differences on the basis of Hedges's adjusted g, and 95% confidence intervals (CIs) were calculated for all eligible studies and were combined to measure the pooled data using random-effects model.

RESULTS

A total of 32 studies including 27 case-control and 5 cohort studies were included in the current study. Fetuin-A levels in T2D patients were significantly higher than control groups [Hedges' g = 1.73, 95% CI (1.25-2.22), P < 0.001], with significant heterogeneity across studies (P < 0.001, I ² = 98.46%). Findings from meta-analyses of cohort studies showed a statistically significant association between fetuin-A levels and T2D risk [rate ratio = 1.62, 95% CI (1.26-2.08), P < 0.001], with no significant heterogeneity (P = 0.10, I ² = 46.06%).

CONCLUSION

We found a significant relationship between the fetuin-A levels with T2D risk. Although fetuin-A may be as a potential screening and prediction biomarker or a therapeutic target in T2D patients, further studies are required in this regard.

Fetuin-A levels and risk of type 2 diabetes mellitus: a systematic review and meta-analysis

AIMS

Fetuin-A has been linked to insulin resistance and obesity. Its role in the pathogenesis of type 2 diabetes (T2DM) has also been discussed. We aimed to investigate the prospective association of fetuin-A and the risk of T2DM in a systematic review and meta-analysis.

METHODS

A systematic search of studies from the MEDLINE, EMBASE, Pubmed and Web of Science using fetuin-A, diabetes and various synonyms was conducted up to June 5, 2017. Relevant studies were extracted by two reviewers independently. The quality of studies was assessed using Newcastle-Ottawa scales. Overall estimates were pooled using fixed effect with inverse variance meta-analysis. Subgroup analyses by gender, study population, techniques of assessing fetuin-A, diabetes ascertainment methods, follow-up duration and measures of association were conducted.

RESULTS

Seven studies comprising a total of 11,497 individuals and 2176 cases of T2DM were included in the systematic review and meta-analysis. Overall, one SD increment of fetuin-A level was associated with a 23% greater risk of incident T2DM (RR: 1.23, 95% CI 1.16-1.31). No significant heterogeneity or publication bias was found. The association was relatively stable across different subgroups. However, the association seemed only evident in women, but not in men.

CONCLUSIONS

Higher circulating fetuin-A levels were associated with increased risk of T2DM. However, the causality deserved further analysis.

Usefulness of serum fetuin-A level as a marker of erectile dysfunction

This study aimed to evaluate the correlation between serum levels of fetuin-A and the presence and severity of erectile dysfunction (ED) in Egyptian population. The study was performed on 60 ED patients and 20 age-matched healthy controls. A comprehensive medical history and complete physical examination were obtained and performed in all participants. ED and its severity were assessed via International Index of Erectile Function (IIEF-5). Doppler ultrasound, fasting blood glucose level, complete lipid profile, serum total testosterone (TT) and serum fetuin-A were performed. Our results revealed that there were no statistically significant differences between the ED group and the controls regarding body mass index, fetal bovine serum, cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL) and triglyceride (TG). However, IIEF-5 and serum TT levels were significantly lower in ED patients than controls. Regarding serum fetuin-A, our data demonstrated that ED patients had significantly lower serum fetuin-A levels than controls. In addition, patients with severe ED had lower fetuin-A levels than moderate and mild ED (P<0.001). Serum fetuin-A levels are positively correlated with cholesterol, LDL, TG and IIEF-5 and negatively correlated with HDL. In conclusion, serum fetuin-A level could be a potentially useful and sensitive biomarker for ED diagnosis.

Alterations in serum levels of fetuin A and selenoprotein P in chronic hepatitis C patients with concomitant type 2 diabetes: A case-control study

BACKGROUND

Insulin resistance (IR) and type 2 diabetes mellitus (T2DM) are serious extrahepatic manifestations of chronic hepatitis C virus (HCV) infection. However, the mechanism underlying the IR in chronic HCV is obscure. Hepatokines are group of liver-derived protein, which affect the glucose and lipid metabolism in several tissues. Fetuin A (also known as human α2-HS-glycoprotein) is one of the hepatokines, which was recognized as a natural inhibitor of the insulin receptor tyrosine kinase in liver and skeletal muscle. Additionally, selenoprotein P has emerged as an important hepatokine, which primarily acts as selenium transporter and has been reported to be implicated in glucose homeostasis in human.

OBJECTIVE

The aim of the current case-control study was to investigate the serum levels of both fetuin A and selenoprotein P in chronic hepatitis C patients with or without T2DM and to correlate their levels with other biochemical parameters of insulin resistance.

MAIN FINDINGS

Our results showed that, serum fetuin A levels increased significantly in HCV patients compared with controls (P<0.01) and surplus increase was found in HCV with concomitant T2DM (P>0.001). However, selenoprotein P levels significantly elevated only in patients with both HCV and T2DM (P<0.05) compared with the healthy subjects. Both fetuin A and selenoprotein P were positively correlated with fasting blood glucose. Yet, only fetuin A was significantly correlated to the HOMA-IR (r=0.28; P=0.03).

CONCLUSIONS

These results indicate crucial roles played by fetuin A and selenoprotein P in the IR caused by HCV and that both hepatokines may be targets for the development of therapies to treat or inhibit insulin resistance associated to HCV. However, further studies on large scale should be conducted to confirm our findings.

Serum Fetuin A Levels: Are They a Reliable Marker for Hepatic Steatosis and Regional Adiposity in Renal Transplant Recipients?

BACKGROUND

Fetuin A is a protein expressed in the liver and it is an important inhibitor of ectopic calcification. High levels of fetuin A correlate with insulin resistance, hepatic steatosis, and regional adiposity in the general population. The association between hepatic steatosis and fetuin A level in renal transplant recipients (RTRs) remains unclear.

AIM

The aim of this study was to explore the relationships between fetuin A, hepatic steatosis, and regional adiposity in RTRs.

METHODS

Data from 44 patients with normal renal functions were included, all subjected to history taking for clinical data, assessment of central obesity and regional adiposity, assessment of hepatic steatosis using abdominal ultrasound (US), and measurements of serum fetuin A concentration using enzyme-linked immunosorbent assay (ELISA) kits.

RESULTS

Our study included 20 females (45.4%) and 24 males (54.6%) with mean age of 41.26 ± 11.2 years. Twenty-four subjects had hepatic steatosis. Fetuin A level in RTRs with hepatic steatosis with a mean of 1642.92 ± 358.91 is significantly higher (P < .001) than those without hepatic steatosis with a mean of 711.74 ± 57.85. Serum fetuin A level was positively correlated with regional adiposity (P = .021) and hepatic steatosis grade (P = .017). Fetuin A level increased with increased duration after renal transplantation (P < .001). The best cutoff value for detecting entrance into phase 3 or 4 steatosis is fetuin of 1862 with sensitivity of 88.9% and specificity of 87.7%.

CONCLUSIONS

Fetuin A is positively correlated with hepatic steatosis and regional adiposity in RTRs. Fetuin increases with increased duration after renal transplantation. Accordingly it may be used as a marker for hepatic steatosis and regional adiposity in these patients.

The Role of AGE/RAGE Signaling in Diabetes-Mediated Vascular Calcification

AGE/RAGE signaling has been a well-studied cascade in many different disease states, particularly diabetes. Due to the complex nature of the receptor and multiple intersecting pathways, the AGE/RAGE signaling mechanism is still not well understood. The purpose of this review is to highlight key areas of AGE/RAGE mediated vascular calcification as a complication of diabetes. AGE/RAGE signaling heavily influences both cellular and systemic responses to increase bone matrix proteins through PKC, p38 MAPK, fetuin-A, TGF-β, NFκB, and ERK1/2 signaling pathways in both hyperglycemic and calcification conditions. AGE/RAGE signaling has been shown to increase oxidative stress to promote diabetes-mediated vascular calcification through activation of Nox-1 and decreased expression of SOD-1. AGE/RAGE signaling in diabetes-mediated vascular calcification was also attributed to increased oxidative stress resulting in the phenotypic switch of VSMCs to osteoblast-like cells in AGEs-induced calcification. Researchers found that pharmacological agents and certain antioxidants decreased the level of calcium deposition in AGEs-induced diabetes-mediated vascular calcification. By understanding the role the AGE/RAGE signaling cascade plays diabetes-mediated vascular calcification will allow for pharmacological intervention to decrease the severity of this diabetic complication.

Association between serum fetuin-A level and erectile function

Recent studies have shown that ED is an early symptom of atherosclerosis. Fetuin-A, a glycoprotein secreted by the liver, kidneys and choroid plexus, has been linked to systemic fibrosis and calcification in human and rat studies. Deficiency of this compound may play a role in atherosclerosis and cardiovascular disease progression. The aim of the study was to examine whether serum fetuin-A level is related to erectile function or severity of ED. Sixty ED patients without cardiovascular disease were assigned to one of the three groups (mild, moderate or severe ED) depending on ED severity. Twenty healthy volunteers were included as the control group. The International Index of Erectile Function-5 questionnaire was used to measure erection quality in all four groups. Mean age, body mass index, total testosterone, low- and high-density lipoprotein cholesterol, and triglyceride levels did not significantly differ between the three erectile dysfunction and control groups (P > 0.05). The group with severe ED had a significantly lower mean fetuin-A level than the mild ED and control groups. For both mild and moderate ED groups, the mean serum fetuin-A level was significantly lower in comparison with the control group (P < 0.001). Serum fetuin-A level may be used as a supplemental biochemical parameter in preliminary evaluation of ED.

Proteinuria as the Most Relevant Parameter Affecting Fetuin-A Levels in Preeclampsia

The present study aimed to examine the factors affecting the possible changes in serum fetuin-A in patients with preeclampsia (PE). The examined factors included the parameters of insulin resistance (IR) [(insulin sensitivity (HOMA%S), insulin resistance (HOMA2IR), and beta-cell functions (HOMA%B)], which were calculated using the HOMA2 calculator, and total and ionized calcium and magnesium levels.

Sixty PE patients and thirty healthy pregnant women, which comprised the study group and control group, respectively participated in the present study. Fetuin-A, estradiol, insulin, glucose, total and ionized calcium and magnesium, total protein, albumin, and globulins were measured in their sera.

The results of the present study showed that serum total and ionized magnesium and the I.Ca/Mg ratio decreased in PE women. Although the fasting insulin level and HOMA2IR were higher and HOMA2%S was lower in PE compared with the control women, PE did not appear as an overt insulin-resistant state. Serum fetuin-A was low in PE patients compared with the control group because PE women had proteinuria. Fetuin-A levels were not correlated with the characteristics and IR parameters, cations, and estradiol levels, but it was correlated with the severity of proteinuria.

These results confirmed the hypothesis that proteinuria results in the loss of fetuin-A because it has a low molecular weight.

Comparative effects of metformin and pioglitazone on fetuin-A and osteoprotegerin concentrations in patients with newly diagnosed diabetes: A randomized clinical trial

AIMS

Fetuin-A is a circulating glycoprotein capable of inhibiting insulin signaling both in vivo and in vitro and is positively associated with insulin resistance. Osteoprotegerin (OPG) acts as a regulatory molecule with increased levels in the early stages of diabetes and atherosclerosis, and is also associated with insulin resistance. We investigated the effects of pioglitazone and metformin as representative insulin-sensitizing therapies on fetuin-A and OPG levels.

MATERIALS AND METHODS

In a randomized clinical trial setting (NCT02027103), 88 patients with newly diagnosed type 2 diabetes were randomly assigned to pioglitazone (30 mg/day, n=46) or metformin (1000 mg/day, n=42) for 12 weeks. Various anthropometric and metabolic parameters, fetuin-A, OPG, highly sensitive C-reactive protein (hsCRP), and homeostasis model assessment of insulin resistance (HOMA-IR) were measured at baseline and after three months.

RESULTS

The reduction in fasting plasma glucose and haemoglobin A1c levels was comparable in the two arms. Pioglitazone resulted in a significant reduction in both fetuin-A and OPG in men, but only fetuin-A in women. Metformin was only effective in lowering OPG levels in women. When compared, both medications were equally effective with regard to fetuin-A and OPG reduction in women (p=0.413 and 0.359, respectively). In men, pioglitazone more effectively decreased fetuin-A levels in both uni- (p=0.011) and multivariate models (p=0.015) and OPG levels in only uni- (p=0.023) but not the multivariate model (p=0.547).

CONCLUSIONS

Metformin and pioglitazone differentially affect fetuin-A and osteoprotegrin levels in diabetic women and men. The level of change may not necessarily be associated with the amelioration of insulin resistance.

Serum Fetuin-A Associated With Fatty Liver Index, Early Indicator of Nonalcoholic Fatty Liver Disease: A Strobe-Compliant Article

Increased fetuin-A has been reported in association with type 2 diabetes and other metabolic diseases. However, the large population data concerning fetuin-A and nonalcoholic fatty liver disease (NAFLD) were limited. In this study, we aimed to investigate the association of serum fetuin-A with fatty liver index (FLI), the indicator of NAFLD. A population-based cross-sectional analysis was performed in 5219 middle-aged and elderly participants who were recruited from 2 nearby urban communities in Shanghai, China. Serum fetuin-A concentrations were measured by enzyme-linked immunosorbent assay (ELISA). The fourth quartiles of FLI, alanine aminotransferance (ALT), aspartate aminotransferance (AST), and γ-glutamyl transpeptadase (GGT) were defined as elevated FLI, ALT, AST, and GGT, respectively. Fetuin-A was positively associated with log-transformed-FLI, -ALT, -AST, and -GGT after adjustment for the confounding factors (all P < 0.05). Multivariate logistic regression analysis showed that each one-standard deviation increase in serum fetuin-A (120.1 mg/L) was associated with 12% (95% confidence interval [CI] 1.01-1.25, P = 0.04), 13% (95% CI 1.06-1.21, P < 0.001), and 10% (95% CI 1.03-1.17, P = 0.005) increased risk of elevated FLI, ALT, and AST, respectively. Categorical analysis showed that as compared to the lowest quartile, the highest quartile of serum fetuin-A associated with a 35% (95% CI 0.98-1.86), 50% (95% CI 1.24-1.83), and 33% (95% CI 1.10-1.60) increased risk of elevated FLI, ALT, and AST, respectively. No significant association was found with GGT. In Chinese adults, serum fetuin-A concentrations were significantly associated with elevated FLI, ALT, and AST, the early indicators of NAFLD.

Usefulness of fetuin-A to predict risk for cardiovascular disease among patients with obstructive sleep apnea

Patients with obstructive sleep apnea (OSA) are at increased risk for cardiovascular diseases (CVDs). Fetuin-A, a novel hepatokine, has been associated with the metabolic syndrome (MetS), insulin resistance, and type 2 diabetes mellitus, all of which are highly prevalent in patients with OSA and associated with increased CVD risk. The goal of this study was to determine whether fetuin-A could be involved in the pathogenesis of CVD risk in patients with OSA, through relations of fetuin-A with MetS components and/or insulin resistance. Overweight or obese, nondiabetic volunteers (n = 120) were diagnosed with OSA by in-laboratory nocturnal polysomnography. Steady-state plasma glucose concentrations derived during the insulin suppression test were used to quantify insulin-mediated glucose uptake; higher steady-state plasma glucose concentrations indicated greater insulin resistance. Fasting plasma fetuin-A and lipoprotein concentrations were measured. Whereas neither the prevalence of MetS nor the number of MetS components was associated with tertiles of fetuin-A concentrations, the lipoprotein components of MetS, triglycerides and high-density lipoprotein cholesterol, increased (p <0.01) and decreased (p <0.05), respectively, across fetuin-A tertiles. Additionally, comprehensive lipoprotein analysis revealed that very low density lipoprotein (VLDL) particles and VLDL subfractions (VLDL1+2 and VLDL3) were increased across fetuin-A tertiles. In contrast, neither insulin resistance nor sleep measurements related to OSA were found to be modified by fetuin-A concentrations. In conclusion, abnormalities of lipoprotein metabolism, but not MetS or insulin resistance per se, may represent a mechanism by which fetuin-A contributes to increased CVD risk in patients with OSA.

Association of plasma Fetuin-A and clinical characteristics in patients with new-onset type 2 diabetes mellitus

CONTEXT

Fetuin-A is an abundant plasma protein known to inhibit insulin signaling and pathologic calcification, has emerged as a promising candidate biomarker for diabetes risk.

OBJECTIVE

The objective of this study was to investigate the relationships between plasma Fetuin-A level with clinical characteristics in patients with new-onset type 2 diabetes mellitus (nT2DM).

SUBJECTS AND METHODS

Plasma Fetuin-A levels, and clinical characteristics were assessed in 100 patients with nT2DM and 100 normal glucose tolerance (NGT).

RESULTS

nT2DM subjects had significantly higher Fetuin-A levels than NGT subjects (368.5 ± 15.6 vs 152.7 ± 7.1 mg/ml, P < 0.01). In the Pearson's correlation coefficients, Fetuin-A levels and clinical parameters. Fetuin-A was positively correlated with HOMA-insulin resistance index (HOMA-IR), carotid intima media thickness(CIMT), HbA1c, triglyceride (TG), Low-density lipoprotein cholesterol (LDL-C), body mass index (BMI), systolic blood pressure (SBP), fasting plasma glucose (FBG) and 2 h post-glucose load blood glucose (2 h OGTT) (P < 0.05 and P < 0.01), but negatively with fasting plasma insulin (FINS), 2 h plasma insulin after glucose overload (PINS), High-density lipoprotein cholesterol (HDL-C) and HOMA-beta-cell insulin secretion index (HOMA-IS) (P < 0.05 and P < 0.01). However, no significant relationships were observed between plasma Fetuin-A levels and estimated glomerular filtration rate (eGFR), age and gender in nT2DM subjects. In a multiple linear regression analysis, Fetuin-A levels were independently associated with FBG, 2 h OGTT, HOMA-IS, TG, and CIMT (R(2) = 0.6760). CIMT were negatively associated with FINS and HDL-C (r = -0.33, P = 0.008; r = -0.31, P = 0.01, respectively) in the Pearson's analyses. Moreover, they were positively associated with HOMA-IR (r = 0.28, P = 0.03). It showed significant correlations of plasma CIMT with FINS, PINS and HOMA-IR (R(2) = 0.6760).

CONCLUSIONS

Our study suggests that the plasma Fetuin-A levels may be associated with macroangiopathies in nT2DM patients. Therefore, detecting early plasma Fetuin-A levels nT2DM provides an opportunity to intervene of carotid artery disease in diabetic patients and giving timely treatment for the prevention of diabetic vascular complications.

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.

Serum fetuin-A levels in patients with cardiovascular disease: a meta-analysis

Background. Fetuin-A (FA) suppresses arterial calcification, promotes insulin resistance, and appears to be elevated in patients with cardiovascular diseases (CVD), but the data is still inconsistent. To clarify the correlation between serum FA levels and the presence and severity of CVDs, we performed this meta-analysis. Method. Potential relevant studies were identified covering the following databases: PubMed, Embase, Web of Science, Cochrane Library, CISCOM, CINAHL, Google Scholar, China BioMedicine (CBM), and China National Knowledge Infrastructure (CNKI) databases. Data from eligible studies were extracted and included in the meta-analysis using a random-effects model. Results. Ten case-control studies, including 1,281 patients with CVDs and 2,663 healthy controls, were included. The results showed significant differences in serum levels of FA between the CVDs patients and the healthy controls (SMD = 1.36, 95%CI: 0.37–2.36, P = 0.007). Ethnicity-subgroup analysis implied that low serum FA levels are related to CVDs in Caucasians (SMD = 1.73, 95%CI: 0.20–3.26, P = 0.026), but not in Asians (SMD = 1.04, 95%CI: −0.33–2.40, P = 0.138). Conclusion. The data indicated that decreased serum FA level is correlated with the development of CVDs. FA might be clinically valuable for reflecting the progression of CVDs.

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.

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.

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.

Serum Fetuin-A levels, insulin resistance and oxidative stress in women with polycystic ovary syndrome

This study was designed to determine serum Fetuin-A levels and establish whether serum Fetuin-A level is related with insulin resistance, oxidative stress, ovarian hyperandrogenism and dyslipidemia in women with polycystic ovary syndrome (PCOS). Twenty-two patients with PCOS and twenty-one healthy control women were evaluated in this controlled clinical study. Serum Fetuin-A, lipid fractions, glucose, insulin, malondialdehyde (MDA), myeloperoxidase (MPO), glutathione (GSH), superoxide dismutase (SOD) and other hormone (gonadotropins, androgens) levels were measured. The estimate of insulin resistance was calculated by homeostasis model assessment (HOMA-R). The women with PCOS had significantly higher serum fasting glucose, insulin, luteinizing hormone (LH), MDA, Fetuin-A levels, and LH/follicle-stimulating hormone (FSH) ratio, free androgen index (FAI), HOMA-IR than healthy women. However, sex hormone-binding globulin (SHBG) and GSH levels were significantly lower in patients with PCOS compared with controls. Fetuin-A was positively correlated with insulin, HOMA-IR and FAI. Multiple regression analysis revealed that FAI was strong predictor of serum Fetuin-A level. Serum Fetuin-A level was related with insulin resistance and ovarian hyperandrogenism in women with PCOS. These results suggest that Fetuin-A may have a role in triggering the processes leading to insulin resistance and androgen excess in PCOS.

Can serum fetuin-A be regarded as an inflammatory marker among patients with familial Mediterranean fever?

BACKGROUND/AIM

Familial Mediterranean fever (FMF), the most frequent periodic fever syndrome, is an autosomal recessive inherited disease that predominantly affects eastern Mediterranean populations. Fetuin-A is a well known negative acute-phase protein. Studies of this glycoprotein as a marker of inflammation in FMF are limited. We have investigated the relationship between serum levels of fetuin-A and inflammatory markers in patients with FMF before, during, and after FMF attacks.

METHODS

Sixty-seven patients with FMF were enrolled in this study. Serum fetuin-A, seruloplasmin, fibrinogen, C reactive protein (CRP), white blood cell count (WBC), calcium, and erythrocyte sedimentation rate (ESR) were measured three times: during the attack-free period, 12 h after FMF attacks, and 7 days after FMF attacks. Plasma fetuin-A concentration was measured by use of an enzyme-linked immunoassay (ELISA) kit. Correlations and differentiation between the serum fetuin-A and other inflammatory markers in patients with FMF were investigated by use of the paired-samples T test and the Pearson correlation test (p < 0.01).

RESULTS

Serum fetuin-A levels of all FMF patients in the attack period were significantly lower than in the attack-free period (p < 0.001). In contrast, serum seruloplasmin (p < 0.05), fibrinogen (p < 0.001), CRP (p < 0.05), WBC (p < 0.05), and ESR (p < 0.05) were all significantly higher than in the attack-free period. Plasma fetuin-A is significantly and inversely highly correlated with the other inflammatory markers.

CONCLUSION

Fetuin-A might be a novel indicator of disease activity in patients with FMF and could be used as an adjunctive marker for differentiation of FMF attacks. The negative correlation between serum fetuin-A and other inflammatory markers may also be indicative of inflammation-dependent downregulation of fetuin-A expression in FMF patients.

Associations of serum fetuin-A levels with insulin resistance and vascular complications in patients with type 2 diabetes

OBJECTIVE

We examined the relationship between serum fetuin-A, insulin resistance (IR), metabolic syndrome (MS) and vascular complications including cardiac autonomic neuropathy (CAN) in patients with type 2 diabetes mellitus (T2DM).

METHODS

A total of 172 T2DM patients were recruited and evaluated for diabetic microangiopathies (nephropathy, retinopathy and peripheral neuropathy) including CAN. Serum fetuin-A levels were measured by enzyme-linked immunosorbent assay (ELISA), and the IR was assessed by the index of homeostasis model [homeostasis model assessment-insulin resistance (HOMA-IR)]. Atherosclerotic burden was assessed by ankle-brachial index (ABI) and brachial-ankle pulse wave velocity (baPWV).

RESULTS

Serum fetuin-A levels showed significant positive correlations with HOMA-IR (r = 0.196, p = 0.022), and the mean levels of HOMA-IR were significantly increased progressively across fetuin-A tertiles (p for trend = 0.044). Serum fetuin-A showed significant positive correlations with baPWV, systolic blood pressure (BP), total cholesterol, triglycerides, serum fasting c-peptide and negative correlations with ABI. Serum fetuin-A levels were also negatively correlated with serum adiponectin and positively correlated with serum tumour necrosis factor-α (TNF-α). The mean levels of serum fetuin-A were not significantly different according to the presence of each microangiopathies including CAN. Also, the mean levels of serum fetuin-A were not different between patients with MS and without MS.

CONCLUSIONS

This present study showed that levels of serum fetuin-A are significantly associated with IR and arterial stiffness assessed by baPWV, while there are no associations with each microangiopathies in patients with T2DM.

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.

Association of fasting serum insulin and fasting serum glucose levels with cognitive impairment in Chinese nonagenarians/centenarians

In this study, we examined the association of fasting serum insulin (FSI) and fasting serum glucose (FSG) with cognitive impairment in the very elderly using a sample of Chinese nonagenarians/centenarians. This study used data from a survey that was conducted in 2005 on all residents aged 90 years or more in a district with 2,311,709 inhabitants. FSG, FSI, and cognitive function were analyzed. The sample included 661 unrelated Chinese individuals (aged 90-108 years; mean, 93.52 ± 3.37 years; 67.17 % women; FSI, 6.27 ± 2.27 mU/mL; FSG levels, 4.46 ± 1.45 mmol/L). The prevalence of cognitive impairment was 61.81 % and that of hypoinsulinemia was 31.92 %. Individuals with hypoinsulinemia showed lower cognitive function scores (14.81 ± 5.79 vs. 15.78 ± 5.24, t = 2.160, P = 0.031). No differences in cognitive function score between different FSI and FSG groups were significant, and no differences in FSI and FSG between individuals with and without cognitive impairment were statistically significant. Unadjusted multiple logistic regressions showed that hypoinsulinemia, impaired fasting glucose, or diabetes did not change the risk of cognitive impairment significantly. In summary, we found that in elderly subjects, cognitive function appeared associated with FSI, and higher FSI may be associated with enhanced cognitive function.

Plasma levels of fetuin-A and hepatic enzymes and risk of type 2 diabetes in women in the U.S

Fetuin-A interferes with insulin action in animal studies, but data on fetuin-A and diabetes risk in humans are sparse and the role of nonalcoholic fatty liver disease in this association is unknown. From 2000 to 2006, we prospectively identified 470 matched incident diabetes case-control pairs in the Nurses' Health Study, for whom levels of plasma fetuin-A, alanine transaminase (ALT), and γ-glutamyltranspeptidase (GGT) were measured. After multivariate adjustment for covariates, including ALT and GGT, the odds ratio (OR) (95% CI) comparing extreme fetuin-A quintiles was 1.81 (1.07-3.06) (P for trend = 0.009). A mediational analysis showed that this positive association was largely (79.9%) explained by fasting insulin and hemoglobin A(1c) levels; after further adjustment of these factors, the OR (95% CI) comparing extreme quintiles was attenuated to 1.09 (0.56-2.10) (P for trend = 0.42). In addition, liver enzymes did not modify this association (P for interaction = 0.91 for ALT and 0.58 for GGT). When results from this study were pooled with those in three prior prospective investigations of the same association, a consistent, positive association was observed between high fetuin-A levels and diabetes risk: the relative risk (95% CI) comparing high versus low fetuin-A levels was 1.69 (1.39-2.05) (P for heterogeneity = 0.45). These findings suggest that plasma fetuin-A levels were independently associated with higher risk of developing type 2 diabetes.

Fetuin-A levels in hyperthyroidism

OBJECTIVE

Fetuin-A is a protein secreted from the liver that inhibits arterial calcification deposition and can contribute to insulin resistance. Hyperthyroidism is also associated with insulin resistance. It is not known whether hyperthyroidism has an effect on fetuin-A levels.

METHODS

We measured fetuin-A levels and homeostasis model of assessment-insulin resistance before hyperthyroidism treatment was initiated and after euthyroidism was achieved. A total of 42 patients diagnosed with hyperthyroidism were enrolled in this study. Fetuin-A, insulin, high-sensitivity C-reactive protein, fasting blood glucose, free T3 (fT3), free T4 (fT4), and thyrotropin were measured before and after euthyroidism was established.

RESULTS

Basal fasting blood glucose, high-sensitivity C-reactive protein, insulin, c-peptide, homeostasis model of assessment-insulin resistance, fT3, fT4 and fetuin-A levels were significantly decreased after euthyroidism was achieved (Table 1). Basal fasting blood glucose (r:0.407, p:0.008), high-sensitivity C-reactive protein (r:0.523, p<0.0001), insulin (r:0.479, p:0.001), homeostasis model of assessment-insulin resistance (r:0.541, p<0.0001), fT3 (r:0.492, p:0.001) and fT4 (r:0.473, p:0.002) were positively correlated with basal fetuin-A levels. Basal thyrotropin levels were significantly negatively correlated (r:-0.553, p<0.0001) with basal fetuin-A levels.

CONCLUSION

Our findings suggest that hyperthyroidism influences fetuin-A levels.

Advanced research on risk factors of type 2 diabetes

The prevalence of type 2 diabetes is increasing globally and poses a heavy burden on public health and socioeconomic development of all nations. Type 2 diabetes is a multifactorial disease and due to a combination of environmental and genetic risk factors. Many environmental risk factors contribute to the pathogenesis of type 2 diabetes, including lifestyles such as sedentary behaviour, diet, smoking and alcohol consumption, internal environmental factors such as inflammatory factors, adipocytokines and hepatocyte factors, external environmental factors such as environmental endocrine disruptors. This review summarizes current research efforts concentrated on the contributors for accelerated type 2 diabetes epidemic. It also provides a novel prospect for future researches.