Serum Retinol-binding Protein 4 Research Articles

Short-Term Detraining does not Change Insulin Sensitivity and RBP4 in Rodents Previously Submitted to Aerobic Exercise.

Elevated serum retinol binding protein 4 (RBP4) levels were previously described in insulin-resistance states. Exercise training can improve insulin sensitivity and RBP4, but the time-response effect of exercise detraining on RBP4 has not been studied. Thus, we examined the effects of exercise training and short-term detraining on insulin resistance, serum RBP4 levels, and GLUT4 expression in spontaneously hypertensive rats (SHR). Thirty-two male SHR, 4 months old, were submitted to 10-week treadmill training, 5 times/week or kept sedentary, followed by a 2- and 4-day detraining period. Body weight, insulin tolerance test, maximum speed in a maximal exercise test, serum RBP4 (ELISA), and epididymal fat GLUT4 expression (Western blot) were measured. Although all rats gained weight (43%, p=0.004) only the trained group showed a reduction (p<0.001) of epididymal fat weight. Detraining did not change these parameters. Exercise training increased insulin sensitivity (26%, p=0.001) and maximum exercise capacity (80%, p<0.001), benefits not lost after detraining. RBP4 levels were reduced in response to exercise training (45%, p<0.001); detraining did not change these benefits. Trained rats had increased GLUT4 expression (microsomal, ~226%; p<0.001 and plasma membrane, ~55%; p=0.011). A slight reduction in GLUT4 expression in the plasma membrane (~28%, p=0.041), but not in the microsomal fraction, was observed after 4 days of detraining. Exercise training is associated with reduced RBP4 levels, increased insulin sensitivity, and epididymal fat GLUT4 expression. Even short periods of detraining (4 days) were shown to be associated with reversal of higher plasma membrane GLUT4.

Expression of retinol binding protein 4 and nuclear factor-κB in diabetic rats with atherosclerosis and the intervention effect of pioglitazone.

This study aims to investigate the expression of retinol binding protein 4 (RBP4) and the activity of nuclear factor-kappa B (NF-κB) in diabetic rats with atherosclerosis, and to evaluate the intervention effect of pioglitazone. A total of 75 Wistar rats were randomly divided into four groups: Normal control (NC), diabetic rats (DM1), diabetic rats with atherosclerosis (DM2) and diabetic rats treated with pioglitazone (DM + Pio). The activity of NF-κB, the levels of serum and adipose tissue RBP4, fasting plasma glucose (FPG), fasting insulin (FINS), low-density lipoprotein cholesterol (LDL-c), high-density lipoprotein cholesterol (HDL-c), triglycerides (TG) and arteria caudilis systolic blood pressure (SBP) were measured. Percentage of fat mass (PFM), atherogenic index of plasma (AIP) and homeostasis model assessment of insulin resistance (HOMA-IR) were calculated. Compared with the NC and DM + Pio groups, all the parameters mentioned above increased significantly in the DM1 and DM2 groups, with the exception that HDL-c decreased. Pearson analysis showed that RBP4 in serum and adipose tissue were positively associated with TG, LDL-c, FINS, PFM, AIP, HOMA-IR, NF-κB, SBP and negatively associated with HDL-c. Multivariable logistic regression analysis showed that serum RBP4 and TG were predictors for the presence of diabetic atherosclerosis. In conclusion, RBP4 may be an effective predictor for diabetic atherosclerosis; pioglitazone is able to decrease RBP4 and NF-κB, which may partly contribute to its protective effect against diabetic atherosclerosis.

Serum retinol binding protein 4 is negatively related to estrogen in Chinese women with obesity: a cross-sectional study.

BackgroundThe association between serum Retinol Binding Protein 4 (RBP4) and obesity is still controversial. Serum RBP4 levels varies by gender, and estradiol may play a role in the difference. To investigate the participation of sex hormones in the association of RBP4 and obesity in humans, we measured serum RBP4, BMI, and sex hormones in 87 women from the outpatient.MethodsEighty-seven subjects of Chinese women origin from the outpatient (aged 40.22 ± 15.54 years) were enrolled. Subjects with diseases affecting the metabolic state or not suitable to participate in this study were excluded. Anthropometrics and laboratory tests, including lipid profile, luteinizing hormone (LH), follicle stimulating hormone (FSH), prolactin (PRL), estradiol (E2),progesterone (PROG), testosterone (TESTO), and dehydroepiandrosterone (DHEA) were conducted. Serum RBP4 was detected by an enzyme immunoassay kit and validated by quantitative Western blotting.ResultsCirculating RBP4 levels were positively associated with BMI, waist circumference, waist-to-hip ratio (WHR), systolic and diastolic (SBP), diastolic blood pressure (DBP), triglycerides (TG), low high-density lipoprotein cholesterol(LDL-c), and testosterone (TESTO) in the total group. While only in obese individuals, serum RBP4 levels were negatively associated with E2. The highest value was in the subjects with both obesity and the low estrogen level. Multiple linear regression analysis revealed that RBP4 correlated independently with TG, TC and insulin in all subjects, TC in non- obese individuals. However, E2 were significantly associated with serum RBP4 only in obese individuals.ConclusionsRBP4 could be a marker of obesity-related factors; estrogen was negatively related to RBP4 and might be one of the influential factors.

Effects of phenolic-rich extracts of Clinacanthus nutans on high fat and high cholesterol diet-induced insulin resistance.

BackgroundClinacanthus nutans is used traditionally in many parts of Asia to improve well-being, but there are limited studies on its efficacy. We explored the potential use of C. nutans for prevention of high fat and high cholesterol diet-(HFHC-) induced insulin resistance in rats.MethodsThe leaf of C. nutans was extracted using water (AL extract) and methanol (AML extract), and the extracts were fed to rats alongside the HFHC diet for 7 weeks, and compared with simvastatin. Oral glucose tolerance test, and serum insulin, retinol binding protein 4 (RBP4), adiponectin and leptin were measured. Homeostatic model assessment of insulin resistance (HOMA-IR) was computed, while transcriptional regulation of hepatic insulin signaling genes was also assessed.ResultsGlycemic response was higher in the HFHC group compared with the AL and AML groups, which also had lower serum RBP4, fasting glucose, insulin and HOMA-IR. Serum adiponectin levels were higher, while leptin levels were lower in the AML and AL groups compared to the HFHC group. There was upregulation of the Insulin receptor substrate, phosphotidyl inositol-3-phosphate, adiponectin receptor and leptin recetor genes, in comparison with the HFHC group.ConclusionsOverall, the results showed that the HFHC diet worsened metabolic indices and induced insulin resistance partly through transcriptional regulation of the insulin signaling genes. C.nutans, on the other hand, attenuated the metabolic effects and transcriptional changes induced by the HFHC diet. The results suggested that C.nutans may be a good source of functional ingredient for the prevention of insulin resistance.Electronic supplementary materialThe online version of this article (doi:10.1186/s12906-016-1049-5) contains supplementary material, which is available to authorized users.

The relationship between serum adipocytokines and Graves' ophthalmopathy: A hospital-based study.

Adipocytokines are thought to be associated with inflammatory disorders and autoimmune diseases. However, limited information is available on the relationship between serum adipocytokine levels, Graves' disease (GD), and Graves' ophthalmopathy (GO). The present study examined the relationship between serum adipocytokine levels and GD and GO. A total of 80 patients with GD participated in this study. The medical records of patients were reviewed retrospectively. GO activity was assessed using the clinical activity score (CAS). GO severity was assessed by the modified NOSPECS classification and included soft tissue involvement, proptosis, and extraocular muscle involvement. Serum adiponectin, leptin, resistin, and retinol-binding protein 4 (RBP-4) levels were measured using commercially available enzyme-linked immunosorbent assays. The prevalence of GO was 36.3%. Serum adiponectin, leptin, and resistin levels were significantly higher in patients with GO than in those without GO. The CAS was positively correlated with serum adiponectin and leptin levels. The total eye score was positively correlated with serum adiponectin, leptin, resistin, and RBP-4 levels. A multivariate analysis revealed that serum leptin and resistin levels were associated with the presence of GO after adjusting for clinical factors. Free thyroxine was negatively correlated with serum leptin level. These results suggest that adipocytokines, such as leptin and resistin, may play a role in inflammatory and autoimmune processes of GD and GO. Future studies with larger numbers of patients are required to establish relationships between serum adipocytokines levels and GO and ascertain the role of adipocytokines in GD and GO.

Retinol-binding protein 4 in obese and obese-diabetic postmenopausal women in Montenegro

Introduction: Menopause is associated with an increase in visceral fat and obesity and is the leading risk factor for insulin resistance (IR) and type 2 diabetes mellitus (T2DM). Recent evidence suggests that retinol-binding protein 4 (RBP4) is not an independent determinant of IR and its role in human glucose metabolism is not well clarified. We examined RBP4 and its association with IR, cardiometabolic and kidney parameters in obese postmenopausal women with and without T2DM.Methods: Basic anthropometric, biochemical parameters, and blood pressure (BP) were determined in 50 obese diabetic and 50 obese non-diabetic sedentary postmenopausal women, and compared with 50 healthy normal weight controls.Results: Higher levels of RBP4 were observed in obese individuals, as compared with normal weight group (p=0.033). However, we did not find significant difference between obese non-diabetic and obese-diabetic individuals (p=0.583). Serum RBP4 did not correlate with anthropometric measurements or any indicator of glucose metabolism in diabetic group, whereas RBP4 correlated with creatinine (r=0.416, p=0.003), eGFR (r= -0.304, p=0.032) and triglycerides (r=0.484, p&lt;0.001). In obese non-diabetic group, correlations were observed with fasting glucose (r=0.346, p=0.014), insulin (r=0.292, p=0.038), HOMA-IR (r=0.329 p=0.020), HbA1c (r=0.326, p=0.021), creatinine (r=0.399, p=0.004), eGFR (r= -0.389, p=0.005), HDL-c (r= -0.316, p=0.025), triglycerides (r=0.461, p&lt;0.001), and systolic BP (r=0.286, p=0.044). In multiple regression analysis, triglycerides (Beta=0.302, p&lt;0.001) and eGFR (Beta= -0.188, p=0.015) were independent predictors of RBP4.Conclusions: Serum RBP4 is not increased in obese type 2 diabetic postmenopausal women, but is associated with triglycerides and eGFR independently of diabetes.

Medullary Thyroid Carcinoma--Circulating Status of Vaspin and Retinol Binding Protein-4 in Iranian Patients.

Vaspin and Retinol binding protein-4 (RBP4) are new adipokines mainly produced by adipose tissue. Considering that medullary thyroid carcinoma (MTC) is a malignant neuroendocrine tumor, and to date the relationship between serum levels of vaspin and RBP4 with MTC has not been studied, in this matched case-control study we evaluated their possible significance to this tumor type. A total of 45 patients with MTC (21 males and 24 females) and 45 healthy persons as a control group (24 males and 21 females) were selected. The two groups were matched for age, sex and body mass index. Serum Vaspin and RBP4 levels were measured by enzyme-linked immunosorbent assay (ELISA) methods in both groups. Also, weight and height were measured and body mass index was calculated too. In total, patients with MTC had significantly higher serum vaspin levels compared to the controls (0.52 ng/ml vs. 0.45 ng/ml, P=0.0241). However, no significant difference was found in serum RBP4 concentrations between the patients with MTC and the controls (15.2±2.55 μg/ml versus 15.1±3.34 μg/ml, p>0.05). The results of this study demonstrated that serum RBP4 levels in MTC patients are not significantly different from those found in healthy individuals and did not correlate with MTC. On the other hand, higher levels of serum vaspin are associated with an increased risk of MTC. Thus Vaspin may be a novel and promising biomarker for diagnosis or confirmation of MTC in conjunction other specific tumor markers.

The effect of topical treatment and psoriasis severity on serum retinol-binding protein-4 levels

Objective: Psoriasis has been considered as chronic systemic disease. Retinol-binding protein-4 (RBP-4) might play a role in psoriasis and its comorbidities. The aim of this study was to investigate the associations between serum RBP-4 levels and disease severity, indicators of inflammation or metabolic syndrome and changes after topical treatment in psoriatic patients. Methods: Thirty-seven patients with relapse of plaque-type psoriasis and 16 healthy volunteers were examined. Blood samples were collected before and after 14 days of therapy. Serum RBP-4 concentrations were examined by enzyme-linked immunosorbent assay for correlation with psoriasis area and severity index (PASI), body mass index (BMI), inflammatory and biochemical markers and with efficacy of topical treatment. Results: RBP-4 serum levels were increased in psoriatics compared to the controls, but without statistical significance (p = 0.2). No significant correlations between investigated adipokine and several indicators of metabolic disorders, nor BMI or PASI were found. A significant negative correlation with CRP was noted. After topical treatment serum RBP-4 level did not significantly change (p = 0.3), despite clinical improvement. Conclusion: RBP-4 might have a protective role in terms of chronic inflammation and comorbidities of psoriasis. The adipokine is presumably not useful in determining severity and the effectiveness of antipsoriatic treatment.

Transgenic Mice Overexpressing Serum Retinol-Binding Protein Develop Progressive Retinal Degeneration through a Retinoid-Independent Mechanism

Serum retinol-binding protein 4 (RBP4) is the sole specific transport protein for retinol in the blood, but it is also an adipokine with retinol-independent, proinflammatory activity associated with obesity, insulin resistance, type 2 diabetes, and cardiovascular disease. Moreover, two separate studies reported that patients with proliferative diabetic retinopathy have increased serum RBP4 levels compared to patients with mild or no retinopathy, yet the effect of increased levels of RBP4 on the retina has not been studied. Here we show that transgenic mice overexpressing RBP4 (RBP4-Tg mice) develop progressive retinal degeneration, characterized by photoreceptor ribbon synapse deficiency and subsequent bipolar cell loss. Ocular retinoid and bisretinoid levels are normal in RBP4-Tg mice, demonstrating that a retinoid-independent mechanism underlies retinal degeneration. Increased expression of pro-interleukin-18 (pro-IL-18) mRNA and activated IL-18 protein and early-onset microglia activation in the retina suggest that retinal degeneration is driven by a proinflammatory mechanism. Neither chronic systemic metabolic disease nor other retinal insults are required for RBP4 elevation to promote retinal neurodegeneration, since RBP4-Tg mice do not have coincident retinal vascular pathology, obesity, dyslipidemia, or hyperglycemia. These findings suggest that elevation of serum RBP4 levels could be a risk factor for retinal damage and vision loss in nondiabetic as well as diabetic patients.

Correlation of serum retinol binding protein 4 and cystatin C with pigmented pretibial pathes in type 2 diabetes mellitus

A total of 165 type 2 diabetic patients were divided into two groups with pigmented pretibial pathes(PPP group)and no PPP(NPPP group). 50 subjects with normal glucose regulation were used as a control group(NGR group). The records of sex, age, diabetes duration, body mass index(BMI), systolic blood pressure(SBP), diastolic blood pressure, high density lipoprotein-cholesterol, low density lipoprotein-cholesterol, fasting blood glucose(FBG), 2 h postpradial plasma glucose(2hPG), triglyceride(TG), total cholesterol, HbA1C, retinol binding protein 4(RBP4), cystatin C(Cys C)were analyzed. The results showed that BMI, FBG, 2hPG, TG, and Cys C levels in NPPP group were higher than those in NGR group(all P<0.01). The levels of BMI, SBP, FBG, 2hPG, TG, Cys C, and RBP4 in PPP group were higher than those in NGR group(P<0.01 or P<0.05), while diabetes duration, FBG, 2hPG, HbA1C, Cys C, and RBP4 in PPP group were higher than those in NPPP group(P<0.01). Pearson correlation analysis revealed that serum RBP4 and Cys C were in linear positive correlation(r=0.77, P<0.01). The areas under receiver operating characteristic curve of RBP4 and Cys C were 0.81 and 0.78, respectively(P<0.01). The results of binary logistic regression analysis showed that diabetes duration, HbA1C, RBP4 were related to PPP(r=0.37, 0.26, 0.22, P<0.05 or P<0.01). Key words: Diabetes mellitus, type 2; Pigmented pretibial pathes; Retinol binding protein 4; Cystatin C

Correlation of retinol binding protein 4 with metabolic indexes of glucose and lipid, bile cholesterol saturation index

To measure retinol binding protein 4 (RBP4) levels in serum and bile and to analyze their relationship with insulin resistance, dyslipidemia or cholesterol saturation index (CSI). A total of 60 patients with gallstone were divided into a diabetes group (n=30) and a control group (n=30). The concentrations of RBP4 in serum and bile were detected by enzyme-linked immunosorbent assay (ELISA). Enzyme colorimetric method was used to measure the concentration of biliary cholesterol, bile acid and phospholipid. Biliary CSI was calculated by Carey table. Partial correlation and multiple linear regression analysis were used to evaluate the correlation between the RBP4 levels in serum or bile and the above indexes. The RBP4 concentrations in serum and bile in the diabetes group were significantly elevated compared with those in the control group (both P<0.01). There was no significant difference in the serum total bile acid (TBA), serum triglyceride (TG), serum high-density lipoprotein (HDL), bile TBA, bile total cholesterol (TC) , bile phospholipids and bile CSI between the 2 groups (all P>0.05); but the serum TC, low density lipoprotein (LDL), fasting blood glucose (FBG), fasting insulin (FINS), and homeostasis model assessment for insulin resistance (HOMA-IR) in the diabetes group were significantly increased compared to those in the control group (all P<0.05). The partial correlation analysis, which was adjusted by age, showed that the bile RBP4 was positively correlated with body mass index (BMI), waist circumference (WC), FINS, FBG, TC, LDL and HOMA-IR (r=0.283, 0.405, 0.685, 0.667, 0.553, 0.424 and 0.735, respectively), and the serum RBP4 was also positively correlated with the WC, FINS, FBG, TC, LDL and HOMA-IR (r=0.317, 0.734, 0.609, 0.528, 0.386 and 0.751, respectively). Stepwise multivariate linear regression analysis suggested that the HOMA-IR, BMI and WC were independently correlated with the level of bile RBP4 (multiple regression equation: Ybile RBP4=2.372XHOMA-IR+0.420XBMI+0.178XWC-26.813), and the serum RBP4 level was correlated with the HOMA-IR and WC independently (multiple regression equation: Yserum RBP4=2.832XHOMA-IR +0.235XWC-20.128). Multiple regression equations showed that HOMA-IR was the strongest correlation factor with RBP4. RBP4 concentrations in serum and bile in the diabetes group are significantly higher than those in the control group. HOMA-IR, BMI and WC are independently correlated with the level of bile RBP4. HOMA-IR and WC are independently correlated with the serum RBP4 level. HOMA-IR is the strongest correlation factor with RBP4. RBP4 might play an important role in the course of gallstone formation in Type 2 diabetes mellitus.

Retinol-binding protein-4 and hs-CRP levels in patients with migraine.

Retinol-binding protein-4 (RBP4) and high-sensitivity C-reactive protein (hs-CRP) levels are associated with inflammation in patients with migraine. The release of proinflammatory cytokines during migraine results in recurrent sterile neurogenic inflammation. This study aimed to determine the correlation between RBP4 and hs-CRP levels, and migraine, which is considered an inflammatory disease. The study included 48 migraine patients and 40 age- and gender-matched controls. Migraine was diagnosed according to International Classification of Headache Disorders-II. The serum RBP4 level was measured using a commercial ELISA kit and hs-CRP was measured using an enzyme immunoassay test kit. The serum RBP4 level was significantly lower in the migraine patients than in the controls (P < 0.001), whereas the hs-CRP level was significantly higher in the migraine patients (P < 0.001). RBP4 and hs-CRP levels did not differ between the migraine patients with and without aura (P > 0.05). Migraine headache severity, frequency and duration were not correlated with serum RBP or hs-CRP levels (P > 0.05). The observed high hs-CRP level and low RBP4 level in migraine patients suggest that vitamin A might play a major role in the pathogenesis of migraine. It is known that inflammation is a key factor in many diseases. Additional research might result in a better understanding of the anti-inflammatory effects of vitamin A.

Abstract 344: Association Between Serum Retinol Binding Protein -4 Level and Coronary Artery Disease: A Meta Analysis

Background: Retinol binding protein 4 (RBP-4) is hepatokine/adipokine shown to be strongly associated with traditional and non-traditional (e.g. cytokines) cardiovascular risk factors via impairment of glucose and lipid metabolism and adipose tissue dysfunction. RBP-4 induce endothelial inflammation by stimulating expression of proinflammatory molecules whose effects are mediated via the activation of NADPH oxidase and NF-κB. The association of coronary artery disease (CAD) and RBP4 remains obscure. The objective of this study is to conduct a meta-analysis to evaluate the relationship between serum RBP-4 levels and CAD. Methods: We searched MEDLINE, CIINHAL and COCHRANE databases for studies reporting serum RBP-4 levels in the CAD and non CAD study population. We included case controls, cohort and cross-sectional studies. We calculated the weighted standardized mean difference (SMD) in serum RBP-4 levels between the CAD and control groups. Results: Our search strategy yielded 52 articles and we included 6 case control and 1 cohort study enrolling 4234 participants. The median age of the CAD group was 62yrs (56 - 65.4) compared to 59.4yrs (42.1 - 65.2) in the control group. The median percentage of female population in the CAD group was 63(IQR 53 -82.5) compared to 62(IQR 35.5 - 72) in the control group. The unweighted median serum RBP-4 levels in the CAD group was 33.4mcg/ml (26.59 - 65.7) compared to 29.8mcg/ml (16.5 - 62.5) in the control group. The SMD of RBP-4 level was 0.14 (95% CI 0.08 - 0.20) p&lt;0.001 comparing those in the CAD group and control group. Conclusion: Elevated serum RBP-4 levels is significantly associated with CAD. Current findings warrant the need to further investigate the role of RBP-4 in the development of CAD and its potential to predict incident CAD events.

Novel role for retinol-binding protein 4 in the regulation of blood pressure.

Elevated levels of serum retinol-binding protein 4 (RBP4) contribute to insulin resistance and correlate with increased prevalence of hypertension and myocardial infarction. We sought to determine whether lowering RBP4 would improve blood pressure (BP) and protect against obesity- or angiotensin (Ang)-II-induced hypertension. Systolic and diastolic BP were lower in the RBP4-knockout (RBP4-KO) mice and higher in the RBP4-overexpressing (RBP4-Tg) mice compared with BP in the wild-type (WT) littermates. Carbachol-induced vasodilatation was increased in arteries from the RBP4-KO compared with the WT mice and was impaired in the RBP4-Tg mice. Aortic eNOS(Ser1177) phosphorylation was enhanced ∼50% in the RBP4-KO mice, with no change in total eNOS protein. Feeding a high-fat diet increased BP in the RBP4-KO mice only to the level in the WT mice fed chow and had no effect on aortic eNOS(Ser1177) phosphorylation. Ang-II infusion resulted in 22 mmHg lower systolic BP in the RBP4-KO than in the WT mice, although the relative BP increase over saline infusion was ∼30% in both. Ang-II treatment decreased aortic eNOS(Ser1177) phosphorylation in the WT and RBP4-KO mice, but phosphorylation remained higher in the RBP4-KO mice. Cardiac hypertrophy with Ang-II treatment was diminished by 56% in the RBP4-KO mice. Thus, elevated serum RBP4 raises BP and lack of RBP4 reduces it, with commensurate changes in aortic eNOS(Ser1177) phosphorylation. Lowering RBP4 may reduce BP through enhanced eNOS-mediated vasodilatation and may be a novel therapeutic approach for hypertension.

Serum retinol binding protein 4 is associated with visceral fat in human with nonalcoholic fatty liver disease without known diabetes: a cross-sectional study.

BackgroundHigh serum Retinol Binding Protein 4 (RBP4) levels were associated with insulin-resistant states in humans. To determine which fat compartments are associated with elevated RBP4 levels in humans, we measured serum RBP4 and hepatic fat content (HFC), visceral (VFA) and subcutaneous abdominal fat area (SFA) in 106 subjects with non-alcoholic fatty liver disease (NAFLD) without known diabetes.Methods106 patients with NAFLD (M/F: 61/45, aged 47.44 ± 14.16 years) were enrolled. Subjects with known diabetes, chronic virus hepatitis, and those with alcohol consumption ≥30 g/d in man and ≥20 g/d in woman were excluded. Anthropometrics and laboratory tests, including lipid profile, alanine aminotransferase (ALT), aspartate aminotransferase (AST) and γ-glutamyltransferase (γ-GT) were conducted. HFC, VFA and SFA were determined by CT scan. Serum RBP4 was detected by an enzyme immunoassay kit and validated by quantitative Western blotting.ResultsCirculating RBP4 was negatively associated with high-density lipoprotein cholesterol (HDL-c) (r = −0.392, p < 0.001), but positively with waist-to-hip ratio (WHR) (r = 0.343, p = 0.001), triglyceride (r = 0.330, p = 0.002), VFA (r = 0.298, p = 0.027), systolic blood pressure (r = 0.247, p = 0.020), diastolic blood pressure (r = 0.241, p = 0.023), γ-GT (r = 0.239, p = 0.034), waist circumference (r = 0.218, p = 0.040). Differently, serum RBP4 levels were not associated with HFC (r = 0.199, p = 0.071), SFA, age, BMI, total cholesterol, low-density lipoprotein cholesterol (LDL-c), ALT or AST (all p > 0.05). Multiple linear regression analysis revealed that RBP4 correlated independently with VFA (Standard β = 0.357, p = 0.019) and HDL-c (Standard β = −0.345, p = 0.023) in all subjects, HDL-c (Standard β = −0.315, p = 0.040) in men, VFA/SFA in women (Standard β = 0.471, p = 0.049), not with HFC. However, serum RBP4 was positively correlated with HFC when HFC below 6.34% (r = 0.574, p = 0.001).ConclusionsRBP4 could be a marker of abdominal obesity, however, the role of RBP4 in the pathogenesis of NAFLD is not sufficiently elucidated.

Serum Retinol Binding Protein-4 and Insulin Resistance in Post-menopausal Women with Cardiovascular Disease

Serum Retinol Binding Protein-4 and Insulin Resistance in Post-menopausal Women with Cardiovascular Disease

Changes of serum lipocalin-2 and retinol binding protein-4 levels in patients with psoriasis and Behçet's disease.

The correlation between psoriasis, Behcet's Disease (BD) and metabolic syndrome (MetS) is related to chronic inflammation [1, 2]. It is suggested that the inflammation that is caused by increased cytokines leads to an increase in insulin resistance and MetS. It has been shown that Lipocalin-2 (LCN-2), and Retinol-binding protein-4 (RBP-4) are related to obesity and insulin-resistance in humans [3, 4]. The current study aimed to investigate LCN-2 and RBP-4 levels in psoriasis and BD, which are [...]

Retinol binding protein-4 predicts incident diabetes in Asian Indian men with prediabetes.

The association of retinol binding protein-4 (RBP4) with incident type 2 diabetes (T2DM) in Asian Indian middle-aged men with impaired glucose tolerance (IGT) was studied. This was an ancillary analysis of a subsample from a cohort of participants with IGT in a 2 year prospective diabetes prevention program in India. For this analysis, 71 incident T2DM and 76 non-diabetic cases (non-progressors) based on the final glycemic outcome were selected. Baseline serum RBP4 was measured using competitive enzyme immunoassay. Correlations of RBP4 with relevant anthropometric and biochemical variables and also its association with diabetes were assessed using appropriate statistical analyses. Participants who developed T2DM had higher levels of serum RBP4 (21.3 [IQR: 17.7-24.9] µg/mL) compared with non-progressors (17.3 [IQR: 13.1-21.0] µg/mL; P = 0.001). Levels of RBP4 were lower than in Caucasians. Stepwise linear regression analysis showed that body mass index (BMI), systolic blood pressure, triglycerides, and HbA1c had independent associations with RBP4 levels. Multiple logistic regression analyses showed that RBP4 was independently associated with incident diabetes (odds ratio [OR] [95%confidence interval (CI)]: 1.69 [1.18-2.41]; P = 0.004). Adjustment for study group, age, BMI, waist circumference, 2 H plasma glucose, triglycerides, gamma glutamyl transferase, and insulin resistance weakened the significance of its association (OR [95%CI]: 1.65 [1.03-2.66]; P = 0.038).The results of this preliminary analyses showed that baseline serum RBP4 levels were independently associated with incident diabetes in Asian Indian men with IGT. It may be used as an additional predictor of future diabetes.

Elevated retinol binding protein 4 induces apolipoprotein B production and associates with hypertriglyceridemia.

A high level of retinol binding protein 4 (RBP4) is reported to be associated with insulin resistance in humans. However, evidence from large-scale populations about the relationship between serum RBP4 and metabolic phenotypes is scarce. In the present study, we aimed to evaluate serum RBP4 distribution and its association with metabolic phenotypes among middle-aged and elderly Chinese. Serum concentrations of RBP4 in a cross-sectional sample of 2780 Chinese population aged 50-70 years old in Guangzhou were measured by ELISA. The mean of serum RBP4 concentration was 28.04 μg/mL for male and 37.76 μg/mL for female (P < .01), respectively. Circulating RBP4 was positively correlated with serum triglyceride and apolipoprotein B (apoB) concentrations. The odds ratio (OR) was substantially higher for hypertriglyceridemia (OR, 3.26; 95% confidence interval, 2.36-4.51) in the highest RBP4 quartile compared with those in the lowest quartile after multiple adjustment for confounders. Furthermore, serum RBP4 was significantly associated with fasting glucose, insulin levels, and homeostasis model assessment index-insulin resistance (HOMA-IR). Moreover, we showed that RBP4 enhanced microsomal triglyceride transfer protein (MTP) expression and activity via up-regulation of protein disulfide isomerase (PDI), suppressed low-density lipoprotein receptor (LDLR) expression, and impaired insulin-signaling pathway, leading to inductions in apoB secretion both in vitro and in vivo. Elevated circulating RBP4 concentrations were associated with higher risk of hypertriglyceridemia by inducing the secretion of triglyceride-rich apoB-containing lipoproteins.

The relationship between retinol-binding protein-4 and cardiometabolic risk factors in obese patients with type 2 diabetes mellitus

Background: Retinol-binding protein-4 (RBP4) is an adipocyte-secreted hormone considered to link obesity with cardiovascular complications. The oxidative stress has been implicated in the pathophysiology of obesity. We evaluated serum RBP4 and plasma total thiols (TT) in generalized obesity (GO) and abdominal obesity (AO) in relationship to classical cardiovascular risk factors. Glycated haemoglobin (HbA1c%), C-reactive protein (CRP) and lipid profile were also evaluated. Patients and Methods: Sixty obese patients were recruited [30 abdominally obese (AO) patients, (15 male and 15 female, mean (SD), 49.5 (5.5) years) were measured by waist circumference (WC &gt; 102 cm for men or &gt; 88 cm for women) and waist/hip ratio (WC divided by that of the hips of &gt; 0.9 for men and &gt; 0.85 for women)] and [30 generalized obese (GO) patients (22 male and 8 female; mean (SD); 42.5 (8) years) were measured by body mass index (BMI). [BMI ≥ 30.0-34.9 kg/m2, with normal WC] compared to 20 healthy subjects (14 males and 6 females; mean age (SD); 36.60 (5.97) years). Results: AO had significantly higher circulating RBP4 levels in comparison to GO (p&lt; 0.05). Total thiols levels were significantly lower in AO compared to GO patients (p&lt; 0.05). CRP significantly elevated in AO compared to GO patients (p&lt;0.05). Total serum cholesterol, triglycerides and Hb1Ac% increased with BMI, WC and waist/hip ratio (WHR). Conclusion: The study reveals that RBP4 is autonomously related to visceral fat accumulations and cardiovascular diseases. The study also reveals the beneficial effect of TT against obesity and cardiovascular disease and the potential clinical applicability of RBP4 and total thiols in cardiovascular diseases.