Serum AFBP levels are elevated in patients with nonalcoholic fatty liver disease.

OBJECTIVE: Adipocyte fatty acid-binding-protein (A-FABP), retinol-binding protein 4 (RBP4), and lipocalin-2 have been identified as adipokines that may link obesity, insulin resistance, and metabolic syndrome. Nonalcoholic fatty liver disease (NAFLD) is regarded as a manifestation of metabolic syndrome. We evaluated the relationship of A-FABP, RBP4, and lipocalin-2 to variables related to metabolic syndrome and NAFLD. METHODS: A total of 140 subjects (72 males and 68 females) were included in this study. Subjects were divided into two groups (NAFLD, n = 73 and normal, n = 67) based on the detection of a fatty liver by ultrasonography. RESULTS: Serum A-FABP levels were higher in the NAFLD group than in the normal group (18.42 ± 7.24 ng/mL vs. 15.74 ± 7.02 ng/mL, p = 0.022). After adjusting for age and sex, we observed that body mass index (BMI), diastolic blood pressure, waist circumference, body fat percentage, triglycerides, and serum RBP4 levels were positively associated with serum A-FABP levels in all subjects. Multiple linear regression analysis revealed that systolic blood pressure, diastolic blood pressure, and serum RBP4 levels were independently associated with serum A-FABP levels. In logistic regression analysis, patients in the higher quartiles of A-FABP levels had higher odds ratios (OR) for the presence of NALFD than patients in the lower quartiles (OR: 3.56; 95% confident interval or CI: 1.25, 10.14). CONCLUSIONS: We observed higher serum A-FABP levels in the NAFLD group than in the normal group. However, serum RBP4 and lipocalin-2 levels appeared to have different relationships with several variables related to metabolic syndrome and NAFLD, which contradict results of previous studies.

Effects of a three-month combined exercise programme on fibroblast growth factor 21 and fetuin-A levels and arterial stiffness in obese women.

OBJECTIVE: We examined the relationship between brachial-ankle pulse wave velocity (baPWV) reflecting arterial stiffness and the levels of novel hepatokines fibroblast growth factor 21 (FGF21) and fetuin-A. In addition, we evaluated the effect of a 3-month combined aerobic and resistance exercise programme on FGF21 and fetuin-A levels as well as arterial stiffness in obese women. METHODS: Forty nondiabetic, obese women (body mass index = 27·6 ± 2·4 kg/m(2) ) were included in the study and were compared before and after a 3-month exercise programme, which was composed of 45 min of aerobic exercise at an intensity of 60-75% of the age-predicted maximum heart rate (300 kcal/session) and 20 min of resistance training (100 kcal/session) five times a week. All exercise sessions were supervised by a professional exercise physiologist. RESULTS: At baseline, baPWV levels were correlated with age, body mass index (BMI), systolic blood pressure (SBP), high density lipoprotein cholesterol, fasting glucose and serum FGF21 levels. In a multiple stepwise regression analysis using baPWV as a dependent variable, baPWV levels were associated with age, BMI, SBP, FGF21 and fetuin-A levels (R(2) = 0·744). After the exercise programme, BMI, waist circumference, SBP, diastolic blood pressure and triglyceride levels were significantly decreased. Moreover, baPWV values were significantly improved (P < 0·001) along with modest decrease in FGF21 levels (P = 0·043). However, fetuin-A levels were not changed significantly (P = 0·202). CONCLUSIONS: A 3-month combined exercise programme decreases the FGF21 levels as well as arterial stiffness in obese Korean women.

Effects of a combined aerobic and resistance exercise program on C1q/TNF-related protein-3 (CTRP-3) and CTRP-5 levels.

OBJECTIVE: To examine the effect of a combined exercise program on C1q/tumor necrosis factor-related protein (CTRP) 3 and CTRP-5 levels and novel adiponectin paralogs suggested to be links between metabolism and inflammation and to evaluate sex differences and association with cardiometabolic risk factors in humans with use of a newly developed ELISA. RESEARCH DESIGN AND METHODS: This cross-sectional study explored the implications of CTRP-3 and CTRP-5 on cardiometabolic parameters in 453 nondiabetic Korean adults. In addition, we evaluated the impact of a 3-month combined exercise program on CTRP-3 and CTRP-5 levels in 76 obese women. The exercise program consisted of 45 min of aerobic exercise at an intensity of 60-75% of the age-predicted maximum heart rate (300 kcal/session) and 20 min of resistance training (100 kcal/session) five times per week. RESULTS: Both CTRP-3 and CTRP-5 concentrations were significantly higher in women (P<0.001) than in men (P=0.030). In a multiple stepwise regression analysis, CTRP-3 levels were independently associated with age, sex, and triglyceride, LDL cholesterol, adiponectin, and retinol-binding protein 4 (RBP4) levels (R2=0.182). After 3 months of a combined exercise program, cardiometabolic risk factors, including components of metabolic syndrome, insulin resistance, and RBP4 levels, decreased significantly. In particular, CTRP-3 levels decreased significantly (median [interquartile range] 444.3 [373.8-535.0] to 374.4 [297.2-435.9], P<0.001), whereas CTRP-5 levels were slightly increased (34.1 [28.6-44.3] to 38.4 [29.8-55.1], P=0.048). CONCLUSIONS: A 3-month combined exercise program significantly decreased CTRP-3 levels and modestly increased CTRP-5 levels in obese Korean women.

Elevated serum retinol-binding protein 4 is associated with insulin resistance in older women.

Retinol-binding protein 4 (RBP4), a molecule secreted from adipocytes and hepatocytes, may contribute to insulin resistance and is a potential predictor for type 2 diabetes mellitus. We investigated the association between serum RBP4 concentrations and insulin resistance in perimenopausal women. In addition, we examined associations of serum RBP4 concentrations with age, risk factors of cardiovascular disease, and metabolic syndrome. A total of 73 healthy women were included in this study. Subjects' anthropometric measurements were taken, and body mass index and waist-hip ratio were calculated. Fasting glucose, fasting insulin, serum RBP4, and lipid parameters were examined. These various parameters were compared in subjects younger than and older than 50 years. Serum RBP4 concentrations in women at least 50 years of age were significantly higher than those in women younger than 50 years. In all subjects, serum RBP4 concentrations positively correlated with age, diastolic blood pressure, fasting glucose, and homeostatic assessment model of insulin resistance. After subgroup analysis, serum RBP4 concentrations positively correlated with age, fasting glucose, and homeostatic assessment model of insulin resistance in women at least 50 years of age. In women younger than 50 years, serum RBP4 concentrations positively correlated only with fasting glucose. Serum RBP4 appears to identify age-induced insulin resistance by physiologic changes due to aging or menopause and by increasing hepatic glucose production. However, the clinical implication of RBP4 for detecting cardiovascular disease and metabolic syndrome is not clear.