Serum adipocyte fatty acid binding protein levels are positively associated with subclinical atherosclerosis in Chinese pre- and postmenopausal women with normal glucose tolerance

Adipokines, adiposity, and atherosclerosis

Characterized by a surplus of whole-body adiposity, obesity is strongly associated with the prognosis of atherosclerosis, a hallmark of coronary artery disease (CAD) and the major contributor to cardiovascular disease (CVD) mortality. Adipose tissue serves a primary role as a lipid-storage organ, secreting cytokines known as adipokines that affect whole-body metabolism, inflammation, and endocrine functions. Emerging evidence suggests that adipokines can play important roles in atherosclerosis development, progression, as well as regression. Here, we review the versatile functions of various adipokines in atherosclerosis and divide these respective functions into three major groups: protective, deteriorative, and undefined. The protective adipokines represented here are adiponectin, fibroblast growth factor 21 (FGF-21), C1q tumor necrosis factor-related protein 9 (CTRP9), and progranulin, while the deteriorative adipokines listed include leptin, chemerin, resistin, Interleukin- 6 (IL-6), and more, with additional adipokines that have unclear roles denoted as undefined adipokines. Comprehensively categorizing adipokines in the context of atherosclerosis can help elucidate the various pathways involved and potentially pave novel therapeutic approaches to treat CVDs.

Interplay between Fatty Acid Binding Protein 4, Fetuin-A, Retinol Binding Protein 4 and Thyroid Function in Metabolic Dysregulation

Signalling between the tissues integrating synthesis, transformation and utilization of energy substrates and their regulatory hormonal axes play a substantial role in the development of metabolic disorders. Interactions between cytokines, particularly liver derived hepatokines and adipokines, secreted from adipose tissue, constitute one of major areas of current research devoted to metabolic dysregulation. The thyroid exerts crucial influence on the maintenance of basal metabolic rate, thermogenesis, carbohydrate and lipid metabolism, while its dysfunction promotes the development of metabolic disorders. In this review, we discuss the interplay between three adipokines: fatty acid binding protein type 4, fetuin-A, retinol binding protein type 4 and thyroid hormones, that shed a new light onto mechanisms underlying atherosclerosis, cardiovascular complications, obesity, insulin resistance and diabetes accompanying thyroid dysfunction. Furthermore, we summarize clinical findings on those cytokines in the course of thyroid disorders.

A-FABP in Metabolic Diseases and the Therapeutic Implications: An Update

Adipocyte fatty acid-binding protein (A-FABP), which is also known as ap2 or FABP4, is a fatty acid chaperone that has been further defined as a fat-derived hormone. It regulates lipid homeostasis and is a key mediator of inflammation. Circulating levels of A-FABP are closely associated with metabolic syndrome and cardiometabolic diseases with imminent diagnostic and prognostic significance. Numerous animal studies have elucidated the potential underlying mechanisms involving A-FABP in these diseases. Recent studies demonstrated its physiological role in the regulation of adaptive thermogenesis and its pathological roles in ischemic stroke and liver fibrosis. Due to its implication in various diseases, A-FABP has become a promising target for the development of small molecule inhibitors and neutralizing antibodies for disease treatment. This review summarizes the clinical and animal findings of A-FABP in the pathogenesis of cardio-metabolic diseases in recent years. The underlying mechanism and its therapeutic implications are also highlighted.

Prospective association of serum adipocyte fatty acid-binding protein with heart failure hospitalization in diabetes

AIMS

Adipocyte fatty acid-binding protein (AFABP) is associated with cardiovascular diseases in type 2 diabetes. Whether circulating AFABP levels are associated with the risk of heart failure (HF) in type 2 diabetes remains undefined. We investigated the prospective association of circulating AFABP levels with incident HF hospitalization in type 2 diabetes, and its relationship to the use of sodium glucose co-transporter 2 inhibitors (SGLT2i) which reduce HF risk.

METHODS AND RESULTS

Baseline serum AFABP level was measured in 3322 Chinese participants without known history of cardiovascular diseases or hospitalization for HF, recruited from the Hong Kong West Diabetes Registry. Its association with incident HF hospitalization was evaluated using multivariable Cox regression analysis. Use of SGLT2i was included as a time-dependent covariate. Among these 3322 participants (52.9% men; mean age 60.0 ± 12.6), 176 (5.3%) developed HF hospitalization over a median follow-up of 8 years. Seven hundred and thirty-one (22%) were started on SGLT2i during the study period (empagliflozin 55.1%, dapagliflozin 44.2%, canagliflozin 0.4%, and ertugliflozin 0.3%). Serum AFABP levels were significantly higher in participants who developed HF hospitalization than those who did not (men: 14.8 vs. 8.3 ng/mL; women: 21.5 vs. 14.6 ng/mL; all: 18.6 vs. 10.9 ng/mL, P < 0.001). In multivariable Cox regression analysis, baseline serum AFABP level was significantly associated with incident HF hospitalization [hazard ratio (HR) 1.38, 95% confidence interval (CI) 1.06-1.80, P = 0.019] independent of the use of SGLT2i, in a model also consisting of age; sex; body mass index; smoking status; duration of diabetes; hypertension, dyslipidaemia; atrial fibrillation; presence of chronic kidney disease and albuminuria; glycated haemoglobin and high-sensitivity C-reactive protein levels; and use of metformin, insulin, aspirin, furosemide, and beta-blockers at baseline. High cumulative defined daily dose (cDDD) of SGLT2i was protective of incident HF hospitalization (HR 0.10, 95% CI 0.01-0.68, P = 0.019). The addition of circulating AFABP level to a clinical model of conventional HF risk factors provided significant improvement in the category-free net reclassification index (11.5%, 95% CI 1.6-22.1, P = 0.02) and integrated discrimination improvement (0.3%, 95% CI 0.1-1.7, P = 0.04). A dose-dependent reduction in cumulative incidence of HF hospitalization in response to SGLT2i, based on cDDD, was more clearly observed in participants with a higher baseline AFABP level above the sex-specific median (P for trend <0.01).

CONCLUSIONS

Circulating AFABP level is independently associated with incident HF hospitalization in type 2 diabetes and is potentially helpful in risk stratification for the prevention of HF hospitalization.

Increased Serum Adipocyte Fatty Acid-Binding Protein Levels Are Associated with Decreased Sensitivity to Thyroid Hormones in the Euthyroid Population

Background: Serum adipocyte fatty acid-binding protein (A-FABP) and thyroid hormones are closely associated with metabolic disorders; however, their relationship remains unknown. We aimed at investigating the associations of serum A-FABP levels with single and composite indices of the thyroid system. Methods: The study included 1057 community-based euthyroid participants (age range: 27-81 years) in Shanghai, among whom 601 were women. Serum free triiodothyronine (fT3), free thyroxine (fT4), and thyrotropin (TSH) were measured by electrochemical luminescence immunoassay. The thyroid feedback quantile-based index (TFQI), thyrotropin index (TSHI), and thyrotroph thyroxine resistance index (TT4RI) were calculated to evaluate central sensitivity to thyroid hormones. Peripheral sensitivity to thyroid hormones was evaluated by the fT3 to fT4 ratio (fT3/fT4). Enzyme-linked immunosorbent assay was used to measure serum A-FABP levels. Results: Serum A-FABP levels were 6.41 [95% confidence interval: 6.10-6.74] ng/mL among all subjects. Multiple cardiovascular metabolic risk factors were adjusted in the multivariate linear regression analysis and the multinomial logistic regression analysis (nonordinal). In both sexes, serum A-FABP levels were positively associated with fT4 (men: standardized β = 0.150, p = 0.001; women: standardized β = 0.218, p < 0.001), TFQI (men: standardized β = 0.119, p = 0.009; women: standardized β = 0.165, p < 0.001), and TSHI (men: standardized β = 0.108, p = 0.017; women: standardized β = 0.114, p = 0.005); while they were negatively associated with fT3/fT4 (men: standardized β = -0.122, p = 0.008; women: standardized β = -0.129, p = 0.001). Serum A-FABP levels were not associated with fT3, TSH, or TT4RI. Compared with the first quartile group of TFQI, for every 10 ng/mL increase in A-FABP, the odds ratio (OR) for the third quartile group of TFQI was 2.213 in women (p = 0.035); the ORs for the fourth quartile group of TFQI were 2.614 in men (p = 0.022) and 3.425 in women (p = 0.002). Conclusions: In a euthyroid population, increased serum A-FABP levels were associated with decreased sensitivity to thyroid hormones, suggesting that A-FABP may mediate the "cross-talk" between adipose tissue and the thyroid system.

Atherogenic Index of Plasma: Novel Predictive Biomarker for Cardiovascular Illnesses

BACKGROUND/AIM

Cardiovascular diseases (CVD) are the most important cause of mortality globally. Nevertheless, the World Health Organization have declared that a precise and quick recognition of susceptible individuals to develop CVD is imperative to combat those illnesses. Additionally, developing countries need affordable alternatives to effectively prognosticate cardiovascular events. Therefore, the objective of this study was to assess well-established clinical prognostic markers in Mexican women to identify affordable, specific, and useful tools to predict cardiovascular events.

MATERIAL AND METHODS

A cross-sectional study was performed including 340 healthy women. Anthropometric and clinical measurements were acquired from all enrolled individuals. Also, a blood sample of each participant women was obtained to complete biochemical analyses (triglycerides, glucose, total cholesterol, LDL cholesterol, and HDL cholesterol), and serum asymmetric dimethylarginine (ADMA), and adipocyte-fatty acid binding protein (FABP4) determinations. Finally, with anthropometric, clinical and biochemical determinations, atherogenic indices (Framingham risk score, Castelli's risk index, and atherogenic index of plasma) were estimated.

RESULTS

A mean value of 6.5 ± 7.2 was detected for the Framingham risk score, 3.7 ± 1.3 for Castelli's risk index, and 0.12 ± 0.22 for the atherogenic index of plasma (AIP). Circulating mean ADMA and FABP4 levels found in assessed women were 0.68 ± 0.34 mmol/L and 20.3 ± 16.6 ng/mL, respectively. Furthermore, strong positive relationships (p <0.05) between AIP and serum FABP4 and ADMA concentrations were detected after adjustment by traditional CVD risk factors.

CONCLUSION

In conclusion, AIP could be recommended as a potential biomarker in the early diagnosis of CVD events in developing countries.

Heart rate variability mediates the association between polycyclic aromatic hydrocarbons exposure and atherosclerotic cardiovascular disease risk in coke oven workers

Polycyclic aromatic hydrocarbons (PAHs) metabolites was related to heart rate variability (HRV) reduction and atherosclerotic cardiovascular disease (ASCVD), and ASCVD was also affected by HRV. However, the mediating role of HRV in the association between PAHs exposure and ASCVD risk was largely unknown. We aimed to investigate whether the relation of PAHs exposure with ASCVD risk was mediated by HRV among coke oven workers. A total of 1100 subjects with complete data were qualified in the current study. We measured 12 urinary PAHs metabolites by gas chromatography-mass spectrometry (GC-MS) and HRV indices by 3-channel digital Holter monitors. The associations between urinary PAHs metabolites, HRV indices, and ASCVD risk were explored using generalized linear models or multivariate logistic regression models. A mediation analysis was conducted to examine the role of HRV on the association between PAHs exposure and ASCVD risk. We found that urinary 1-hydroxynaphthalene (1-OHNa), 2-OHNa, and total PAH metabolites (ΣOH-PAH) were dose-responsive associated with increased risk of ASCVD. Compared with lowest quartile, the adjusted odds ratio (OR) for ASCVD risk in the highest quartile were 2.36 for 1-OHNa, 6.58 for 2-OHNa, and 1.60 for ΣOH-PAH (all P_trend<0.05). In addition, significant dose-dependent relationships were found across 2-OHNa quartiles with decreasing HRV indices, which in turn, were positively associated with elevated risk of ASCVD (all P_trend<0.05). Mediation analyses indicated that HRV mediate 2.7%-4.3% of the association between 2-OHNa exposure and higher ASCVD risk. Our data suggested that occupational exposure to PAHs may increase ASCVD risk, which was partially mediated by HRV.

Association of adipokines with hepatic steatosis and fibrosis in chronic hepatitis B patients on long-term nucleoside analogue

BACKGROUND & AIMS

It is unknown how concomitant hepatic steatosis affects disease progression in chronic hepatitis B (CHB). Adipokines such as fibroblast growth factor 21 (FGF21) and adipocyte fatty acid-binding protein (AFABP) have been associated with non-alcoholic fatty liver disease. We determined the significance of these metabolic markers in CHB-related liver injury.

METHODS

We recruited CHB patients on antiviral treatment for transient elastography assessment to determine liver stiffness (advanced fibrosis/cirrhosis, F3/F4, defined by EASL-ALEH criteria) and controlled attenuation parameter (hepatic steatosis, defined as ≥ 248 dB/m). Plasma FGF-21, AFABP and adiponectin levels were measured.

RESULTS

A total of 415 patients [mean age 59.6 years, 71.6% male, median treatment duration 6.2 years] were recruited. Patients with F3/F4 (N = 151) had lower FGF-21 (11.7 vs 13.6 pg/mL, P = 0.055), higher AFABP (126.8 vs 84.1 pg/mL, P < 0.001) and HOMA-IR (7.1 vs 5.1, P = 0.004) levels compared to those without F3/F4 (N = 264). Multivariate analysis showed that FGF-21 level was associated with hepatic steatosis (OR 1.005, 95% CI 1.001-1.009) and F3/F4 (OR 0.993, 95% CI 0.989-0.998), while AFABP level (OR 1.001, 95% CI 1-1.002), body mass index (BMI) (OR 1.107, 95% CI 1.037-1.182) and presence of diabetes mellitus (OR 2.059, 95% CI 1.206-3.516) were associated with F3/F4. With the combined presence of BMI ≥ 25 kg/m² , diabetes and AFABP > 105.9 pg/mL, the odds ratio for F3/F4 was 3.712 (95% CI 1.364-10.105, P = 0.010).

CONCLUSIONS

Low FGF-21 and high AFABP levels were associated with advanced fibrosis/cirrhosis in CHB patients on antiviral treatment. Plasma AFABP, together with other metabolic risk factors, may aid identification of patients lacking fibrosis improvement during antiviral treatment.

Prospective associations of circulating adipocyte fatty acid-binding protein levels with risks of renal outcomes and mortality in type 2 diabetes

AIMS/HYPOTHESIS

Elevated circulating adipocyte fatty acid-binding protein (AFABP) levels have been found to correlate with diabetic nephropathy staging in cross-sectional studies. However, it remains unclear whether these higher serum levels reflect a role of AFABP in the development of diabetic kidney disease (DKD), or simply result from its impaired renal clearance in DKD. Here we investigated prospectively the prognostic importance of serum AFABP level in the development of adverse renal outcomes in a large clinic-based cohort of participants with type 2 diabetes.

METHODS

Baseline serum AFABP levels were measured in 5454 Chinese participants from the Hong Kong West Diabetes Registry. The association between circulating AFABP levels and incident adverse renal outcomes-defined as a composite endpoint of a sustained 40% decline in eGFR, end-stage renal disease requiring renal replacement therapy or kidney transplantation, or renal deaths-was evaluated using multivariable Cox regression analysis.

RESULTS

Over a median follow-up of 5 years, 754 of the 5454 participants developed incident adverse renal outcomes. Elevated circulating AFABP levels were independently associated with incident adverse renal outcomes (HR 1.43, 95% CI 1.31, 1.57, p < 0.001) after adjustments for conventional risk factors for DKD progression. Importantly, the prognostic role of serum AFABP was independent of the baseline albuminuria status or eGFR levels of the study participants.

CONCLUSIONS/INTERPRETATION

Circulating AFABP levels were predictive of incident adverse renal outcomes, even in participants with relatively well-preserved kidney function at baseline, suggesting its potential to be a useful marker for early risk stratification in DKD.

Association of serum adipocyte fatty acid-binding protein and apolipoprotein B /apolipoprotein A1 ratio with intima media thickness of common carotid artery in dyslipidemic patients

BACKGROUND

Diseases caused by atherosclerosis play the most important role in mortality and morbidity worldwide. Serum adipocyte fatty acid binding protein (A-FABP) seems to be a new promising marker to determine the risk of atherosclerosis.

OBJECTIVE

The aim of this study was to evaluate relationships between serum A-FABP levels in studied individuals and to assess the possibility of modeling the intima media thickness of the common carotid artery (C-IMT) using A-FABP levels and other observed characteristics.

METHODS

Seventy two Caucasian individuals were enrolled and divided into 3 groups: dyslipidemic patients with or without metabolic syndrome (MetS+, n=17; MetS-, n= 34) and controls (n=21).

RESULTS

There was confirmed the well-established risk profile of individuals with MetS (unfavorable lipid and lipoprotein profile, as well as increased parameters of insulin resistence and C-IMT). A-FABP concentrations in this group were significantly higher in comparison with both MetS- and controls.

CONCLUSION

Using multiple linear regression models of C-IMT values for all individual data, healthy controls and dyslipidemic patients without metabolic syndrome (MetS-) A-FABP levels were not revealed as an important predictor of C-IMT in our model. In contrast, age, gender, waist circumference, nonHDL cholesterol levels and ApoB/ApoA1 ratio were important repressors of C- IMT in study individuals. This finding may be attributed to the overwhelming effect of other more robust risk factors for atherosclerosis in these individuals.

Circulating Fatty Acid-Binding Protein 4 Concentration Predicts the Progression of Carotid Atherosclerosis in a General Population Without Medication

BACKGROUND

Fatty acid-binding protein 4 (FABP4), which is expressed in both adipocytes and macrophages, is secreted from the cells and acts as an adipokine. An elevated circulating FABP4 level is associated with insulin resistance and atherosclerosis.Methods and Results:We investigated the causative association between FABP4 level and progression of atherosclerosis in subjects of the Tanno-Sobetsu Study, a population-based cohort. In 281 subjects without medication (male/female: 109/172) in the year 2010 or 2013, the carotid intima-media thickness (CIMT) assessed using carotid ultrasonography was significantly correlated with age, adiposity, blood pressure, renal dysfunction and levels of cholesterol, triglycerides, fasting glucose, HbA1c and FABP4 (r=0.331, P<0.001). Multiple regression analysis demonstrated that age, sex and FABP4 concentration were independent predictors of CIMT. A total of 78 (male/female: 29/49) of the 156 subjects in 2010 underwent carotid ultrasonography again in 2013. The change in CIMT each year during that 3-year period (mean±SD: 3.8±22.3 µm/year) was positively correlated with basal levels of high-sensitivity C-reactive protein (hsCRP) (r=0.231, P=0.046) and FABP4 (r=0.267, P=0.018) in 2010. After adjustment for age, sex and hsCRP level, the basal FABP4 level was independently associated with the change in CIMT per year.

CONCLUSIONS

FABP4 concentration is an independent predictor of the progression of carotid atherosclerosis.

Serum Concentrations of New Predictive Cardiovascular Disease Biomarkers in Mexican Women Exposed to Lead

The purpose of this study was to evaluate lead exposure and its relationship with serum levels of predictive CVD biomarkers [asymmetric dimethylarginine (ADMA), adipocyte fatty acid-binding protein (FABP4), adiponectin, and chemerin] in women living in San Luis Potosi, Mexico. A mean blood lead level (BLL) of 11.5 ± 9.00 μg/dL (mean ± standard deviation) was found after all blood samples were analyzed. Regarding serum predictive CVD biomarkers, mean serum level of 0.68 ± 0.38 μmol/L, 20.5 ± 16.5 ng/mL, 12.5 ± 3.30 μg/mL, and 255 ± 130 ng/mL were found for ADMA, FABP4, adiponectin, and chemerin, respectively. Simple significant associations (Pearson´s correlations) between BLL and ADMA (r = 0.17; p = 0.04) and FABP4 (r = 0.23; p = 0.03) were found. Furthermore, a multivariate linear regression model showed that BLL was a significant predictor of serum ADMA (β = 0.06; p = 0.001) and FABP4 (β = 1.75; p = 0.0004) concentrations after adjusting by confounders. For serum chemerin and adiponectin levels, no associations were found with BLL. In conclusion, high serum ADMA and FABP4 (predictive CVD biomarkers) levels were found in women exposed to lead. Consequently, this research can be used as a point of departure for the prevention of CVD events in populations living in sites environmentally impacted with lead.

Contribution of serum adipocyte fatty acid-binding protein levels to the presence of microalbuminuria in a Chinese hyperglycemic population

AIMS/INTRODUCTION

Individuals with type 2 diabetes mellitus are vulnerable to micro- and macrovascular complications in the presence of microalbuminuria. Adipocyte fatty acid-binding protein (A-FABP) was proposed as an indicator for albuminuria in patients with diabetes. The present study aimed to explore the associations between serum A-FABP levels and microalbuminuria in the hyperglycemic population.

MATERIALS AND METHODS

Serum A-FABP levels were detected using sandwich enzyme-linked immunosorbent assay. Microalbuminuria was identified by urinary albumin-to-creatinine ratio (UACR), when the value was between 30-300 mg/g. The participants were divided into the subgroups based on sex and the status of impaired glucose regulation or newly diagnosed type 2 diabetes mellitus.

RESULTS

A total of 939 participants, consisting of 436 men and 503 women, were enrolled. Serum levels of A-FABP were much higher in participants with microalbuminuria than those without microalbuminuria. This result held true for all subgroups (all P < 0.05). For Spearman's correlation analyses, serum A-FABP levels showed a positive relationship with the UACR in men and women (both P < 0.01). Multiple stepwise regression analysis showed that serum A-FABP levels were independently and positively correlated with UACR in both sexes (men: standardized β = 0.256, P < 0.001; women: standardized β = 0.155, P = 0.001). This relationship remained significant in every subgroup (all P < 0.01).

CONCLUSIONS

For hyperglycemic individuals, serum A-FABP levels increased in the presence of microalbuminuria. Serum A-FABP levels were identified as an independent factor positively associated with the UACR.

Serum adipocyte-fatty acid binding protein (FABP4) levels in women from Mexico exposed to polycyclic aromatic hydrocarbons (PAHs)

Recent studies indicate that exposure to polycyclic aromatic hydrocarbons (PAHs) is a very important risk factor for the development of cardiovascular diseases (CVDs). Correspondingly, adipocyte-fatty acid binding protein (FABP4, also known as aP2 and AFABP) has been proposed as a new, meaningful and useful biomarker to predict metabolic and cardiovascular diseases. Therefore, the aim of this study was to evaluate serum FABP4 levels in Mexican women exposed to PAHs. Urinary 1-hydroxypyrene ((1-OHP), exposure biomarker for PAHs) levels were quantified using a high-performance liquid chromatography (HPLC) technique, and serum FABP4 concentrations were analyzed using a commercially available ELISA kit. The mean urinary 1-OHP level found in women participating in this study was 1.30 ± 1.10 μmol/mol creatinine (2.45 ± 2.10 μg/g creatinine). Regarding serum FABP4 concentrations, the levels ranged from 3.80 to 62.5 ng/mL in the assessed population. Moreover, a significant association (p < 0.001) was found between urinary 1-OHP levels and serum FABP4 concentrations in women after adjusting for potential confounding variables. The presented data in this study can be considered only as a starting point for further studies. Then, in order to elucidate whether FABP4 represents a risk factor for CVD disease in humans exposed to air contaminants (such as PAHs), large epidemiological studies are necessary.

Contribution of a first-degree family history of diabetes to increased serum adipocyte fatty acid binding protein levels independent of body fat content and distribution

Background/Objectives:

First-degree relatives of patients with diabetes bear an increased risk of diabetes, overweight/obesity and cardiovascular disease. Accumulating evidence indicates that circulating concentrations of adipokines are altered in individuals with a first-degree family history of diabetes (FHD), but the adipokine adipocyte fatty acid binding protein (A-FABP) has been rarely studied in this population. The present study explored the association between a first-degree FHD and serum A-FABP levels.

Subjects/Methods:

A total of 1962 normoglycemic participants were divided into subgroups of men, premenopausal women and postmenopausal women. Serum A-FABP levels were measured using a sandwich enzyme-linked immunoabsorbent assay. Abdominal fat distribution, including visceral fat area and subcutaneous fat area, was assessed by magnetic resonance imaging.

Results:

Totals of 792 men, 544 premenopausal women and 626 postmenopausal women were enrolled. Serum A-FABP levels were much higher in subjects with a first-degree FHD than in those without an FHD in all subgroups (all P<0.05). Logistic regression analysis revealed an independent and positive relationship between a first-degree FHD and serum A-FABP levels in men (P=0.029), premenopausal women (P=0.036) and postmenopausal women (P=0.008). Multiple stepwise regression analysis showed that a first-degree FHD was an independent factor positively associated with serum A-FABP levels in men (standardized β=0.068, P=0.029), premenopausal women (standardized β=0.090, P=0.018) and postmenopausal women (standardized β=0.102, P=0.004).

Conclusions:

Serum A-FABP levels were increased significantly in normoglycemic individuals with a first-degree FHD. The contribution of the first-degree FHD to the elevated serum A-FABP levels was independent of total body fat content and abdominal fat distribution. Thus, use of serum A-FABP as a biomarker in the first-degree relatives of patients with diabetes may result in overestimation of the risk of obesity-induced metabolic disease and cardiovascular disease.

Association of androgen with gender difference in serum adipocyte fatty acid binding protein levels

Clinical investigations have indicated women have higher levels of adipocyte fatty acid binding protein (A-FABP) than men. The present study aimed to identify factors related to gender difference in serum A-FABP levels. A total of 507 participants (194 men, 132 premenopausal women, and 181 postmenopausal women) were enrolled in the present study. Serum A-FABP levels increased in the order from men to premenopausal women to postmenopausal women in both body mass index categories (<25.0 and ≥25.0 kg/m(2); all P < 0.05). Multiple stepwise regression analyses showed that after adjustment for factors related to serum A-FABP levels, the trunk fat mass was an independent and positive factor of serum A-FABP levels. For men, total testosterone was associated independently and inversely with serum A-FABP levels. For pre- and postmenopausal women, bioavailable testosterone and total testosterone were independent and positive factors associated with serum A-FABP levels, respectively. The present study demonstrated that the androgen was correlated with the serum A-FABP levels negatively in men, but positively in women. With these effects on the fat content, especially trunk fat, androgen might contribute to the gender difference in serum A-FABP levels.

High Serum Adipocyte Fatty Acid Binding Protein Is Associated with Metabolic Syndrome in Patients with Type 2 Diabetes

Adipocyte fatty acid binding protein (A-FABP) is a key mediator of obesity-related metabolic syndrome (MetS). The aim of this study was to evaluate the relationship between A-FABP concentration and MetS in type 2 diabetes mellitus (DM) patients. Fasting blood samples were obtained from 165 type 2 DM volunteers. MetS and its components were defined using diagnostic criteria from the International Diabetes Federation. Among 165 DM patients, 113 patients (68.5%) had MetS. Diabetic persons who had MetS had significantly higher A-FABP levels (P < 0.001) than those without MetS. Female DM persons had higher A-FABP level than man (P < 0.001). No statistically significant differences in A-FABP levels were found in use of statin, fibrate, or antidiabetic drugs. Multivariate forward stepwise linear regression analysis revealed that body fat mass (P < 0.001), logarithmically transformed creatinine (log-creatinine; P < 0.001), female DM patients (P < 0.001), and logarithmically transformed high sensitive C-reactive protein (log-hs-CRP; P = 0.013) were positively correlated, while albumin (P = 0.004) and glomerular filtration rate (GFR; P = 0.043) were negatively correlated with serum A-FABP levels in type 2 DM patients. In this study, higher serum A-FABP level was positively associated with MetS in type 2 DM patients.

Inverse relationship between serum osteocalcin levels and nonalcoholic fatty liver disease in postmenopausal Chinese women with normal blood glucose levels

AIM

Osteocalcin is involved in the progression of nonalcoholic fatty liver disease (NAFLD) in animal models and humans. In this study we investigated the relationship between serum osteocalcin levels and NAFLD in postmenopausal Chinese women.

METHODS

A total of 733 postmenopausal women (age range: 41-78 years) with normal blood glucose levels were enrolled in this cross-sectional study. Women taking lipid-lowering or anti-hypertensive drugs were excluded. Serum osteocalcin levels were assessed using an electrochemiluminescence immunoassay. The degree of NAFLD progression for each subject was assessed through ultrasonography. The fatty liver index (FLI) of each subject was calculated to quantify the degree of liver steatosis.

RESULTS

The median level of serum osteocalcin for all subjects enrolled was 21.99 ng/mL (interquartile range: 17.84-26.55 ng/mL). Subjects with NAFLD had significantly lower serum osteocalcin levels (18.39 ng/mL; range: 16.03-23.64 ng/mL) compared with those without NAFLD (22.31 ng/mL; range: 18.55-27.06 ng/mL; P<0.01). Serum osteocalcin levels decreased with incremental changes in the FLI value divided by the quartile (P-value for trend<0.01). The serum osteocalcin levels showed a negative correlation with the FLI values, even after adjusting for confounding factors (standardized β=-0.124; P<0.01). Binary logistic regression analysis identified an individual's serum osteocalcin level as an independent risk factor for NAFLD (odds ratio: 0.951; 95% confidence interval: 0.911-0.992; P=0.02).

CONCLUSION

Serum osteocalcin levels are inversely correlated with NAFLD in postmenopausal Chinese women with normal blood glucose levels.

Metabolic Syndrome and Menopause: Pathophysiology, Clinical and Diagnostic Significance

Menopause is a risk factor for cardiometabolic diseases, including metabolic syndrome (MetS), type 2 diabetes, and cardiovascular diseases. MetS is a constellation of interdependent factors such as insulin resistance, abdominal obesity, dyslipidemia, and hypertension. The prevalence of MetS in postmenopause is due to loss of the protective role of estrogens and increased circulating androgens resulting in changes to body fat distribution and development of abdominal obesity. Excessive visceral adipose tissue plays an important role due to synthesis and secretion of bioactive substances such as adipocytokines, proinflammatory cytokines, reactive oxygen species, prothrombotic, and vasoconstrictor factors. MetS may also impact risk assessment of breast cancer, osteoporosis and chronic kidney disease, and quality of life during the menopausal transition. Increased MetS has stimulated the exploration of new laboratory tests for early detection and therapies.