Retinol binding protein 4 correlates with and is an early predictor of carotid atherosclerosis in type 2 diabetes mellitus patients

Association between serum retinol-binding protein and lower limb atherosclerosis risk in type 2 diabetes mellitus

BACKGROUND

Serum retinol-binding protein (RBP) is the primary transport protein of circulating vitamin A. RBP has a crucial role in maintaining nutrient metabolism and physiologic homeostasis. Several studies have indicated that serum RBP participates in the progression of diabetes and diabetes-related complications. However, the impact of serum RBP on lower limb atherosclerosis has not been determined in individuals with type 2 diabetes mellitus (T2DM).

AIM

To determine the association between serum RBP and lower limb atherosclerosis in individuals with T2DM.

METHODS

This retrospective study enrolled 4428 eligible T2DM patients and divided the patients into non-lower limb atherosclerosis (n = 1913) and lower limb atherosclerosis groups (n = 2515) based on lower limb arterial ultrasonography results. At hospital admission, baseline serum RBP levels were assessed, and all subjects were categorized into three groups (Q1-Q3) based on RBP tertiles. Logistic regression, restricted cubic spline regression, subgroup analysis, and machine learning were used to assess the association between RBP levels and lower limb atherosclerosis risk.

RESULTS

Among 4428 individuals with T2DM, 2515 (56.80%) had lower limb atherosclerosis. Logistic analysis showed that lower limb atherosclerosis risk increased by 1% for every 1 unit rise in serum RBP level (odds ratio = 1.01, 95% confidence interval: 1.00-1.02, P = 0.004). Patients in the highest tertile group (Q3) had a higher lower limb atherosclerosis risk compared to the lowest tertile group (Q1) (odds ratio = 1.36, 95% confidence interval: 1.12-1.67, P = 0.002). The lower limb atherosclerosis risk gradually increased with an increase in RBP tertile (P for trend = 0.005). Restricted cubic spline analysis indicated a linear correlation between serum RBP levels and lower limb atherosclerosis risk (non-linear P < 0.05). Machine learning demonstrated the significance and diagnostic value of serum RBP in predicting lower limb atherosclerosis risk.

CONCLUSION

Elevated serum RBP levels correlate with an increased lower limb atherosclerosis risk in individuals with T2DM.

Adipokine Levels of RBP4, Resistin and Nesfatin-1 in Women Diagnosed With Gestational Diabetes

Gestational diabetes mellitus (GDM) is a common complication of pregnancy in which women without previously diagnosed diabetes develop chronic hyperglycemia during pregnancy. It is associated with a number of maternal and fetal/neonatal complications. The role of the adipokines retinol binding protein-4, resistin and nesfatin-1 in the development of GDM is relatively poorly understood, but their role in glucose metabolism is suspected and their use as early markers to predict the development of GDM is being sought. The aim of study was to determine the correlation between the levels of selected adipokines (retinol binding protein-4, resistin, nesfatin-1) in women with gestational diabetes mellitus (GDM) and healthy pregnant women and to compare their levels with other clinical and biochemical parameters. Patients with GDM had significantly higher BMI (28.4±4.5 vs. 24.6±4 kg/m2), total cholesterol (6±1.3 vs. 5.3±1.4 mmol/l) and triacylglycerols (1.9±0.8 vs. 1.4±0.7 mmol/l) than women in the control group. RBP4 confirms the significant difference between the groups, it is higher in the control group of healthy pregnant women. The adipokines resistin and nesfatin-1 show no differences between the control and GDM groups, but their ratios with BMI, cholesterol and triacylglycerols, resistin shows elevated levels in the control group. In women with GDM, RBP4 was significantly positively correlated with C-peptide and negatively correlated with total, LDL, and non-HDL cholesterol. Resistin was also negatively correlated with total, LDL, HDL, and non-HDL cholesterol. Nesfatin-1 was only moderately positively correlated with glycated hemoglobin (HbA1C) and fasting glycemia. There is ambiguity in the results of previous studies on the levels of the investigated adipokines in pregnant women with GDM and the interpretation depends on many factors. Keywords: Gestational diabetes, Adipokines, Retinol-binding protein 4, Resistin, Nesfatin-1.

Serum retinol binding protein 4 in individuals with essential hypertension and type 2 diabetes: A cross-sectional study

Background

Cardiometabolic disorders, notably primary hypertension and type 2 diabetes, present substantial global health challenges. The intricate interplay between metabolic and cardiovascular pathways has prompted extensive research into molecular mechanisms linking these conditions. The adipokine Retinol Binding Protein 4 (RBP4), initially recognized for retinol transport, has emerged as a potential biomarker in the network of metabolic and cardiovascular dysfunction. Recent studies implicate RBP4 in insulin resistance and its complications, including hypertension. This study explores RBP4 dynamics in patients with primary hypertension and type 2 diabetes, aiming to contribute valuable insights into diagnostic and therapeutic advancements in managing these interconnected disorders.

Methods

This cross-sectional study, conducted over 2 years in a tertiary healthcare centre of North India, aimed to investigate the serum concentration of Retinol Binding Protein 4 (RBP4) in 119 participants diagnosed with primary hypertension and type 2 diabetes. Ethical guidelines were strictly followed, and comprehensive clinical assessments, including blood pressure measurements, were performed. RBP4 levels were quantified using an ELISA kit, alongside markers of insulin resistance. Statistical analyses, involving t-tests and correlation assessments, sought to unravel potential associations between RBP4, insulin resistance, and blood pressure parameters using SPSS 20.0.

Results

The study comprised 61 healthy control (HC) participants and 58 individuals diagnosed with both essential hypertension and type 2 diabetes (EH+T2D). EH+T2D participants were on average older (45.71 ± 9.29 years vs. 40.34 ± 9.47 years, P = 0.002). Dyslipidemia prevalence was markedly higher in EH+T2D (72.4% vs. 11.4%, P < 0.0001), accompanied by disrupted lipid profiles. Serum RBP4 concentration was significantly elevated in EH+T2D (49.17 ± 19.37 mg/L, P < 0.0001), suggesting its potential role in the shared pathophysiology of primary hypertension and type 2 diabetes. Pearson's correlation analysis revealed associations between RBP4 levels, metabolic, and cardiovascular parameters, underscoring its potential as a link between these conditions.

Conclusion

Elevated serum RBP4 levels suggest its potential as a novel biomarker in the shared pathophysiology of primary hypertension and type 2 diabetes. The correlation analysis highlights the intricate interplay between metabolic, lipid, and cardiovascular parameters, emphasizing the need for holistic interventions.

The essential role of dual-energy x-ray absorptiometry in the prediction of subclinical cardiovascular disease

Subclinical cardiovascular disease (Sub-CVD) is an early stage of cardiovascular disease and is often asymptomatic. Risk factors, including hypertension, diabetes, obesity, and lifestyle, significantly affect Sub-CVD. Progress in imaging technology has facilitated the timely identification of disease phenotypes and risk categorization. The critical function of dual-energy x-ray absorptiometry (DXA) in predicting Sub-CVD was the subject of this research. Initially used to evaluate bone mineral density, DXA has now evolved into an indispensable tool for assessing body composition, which is a pivotal determinant in estimating cardiovascular risk. DXA offers precise measurements of body fat, lean muscle mass, bone density, and abdominal aortic calcification, rendering it an essential tool for Sub-CVD evaluation. This study examined the efficacy of DXA in integrating various risk factors into a comprehensive assessment and how the application of machine learning could enhance the early discovery and control of cardiovascular risks. DXA exhibits distinct advantages and constraints compared to alternative imaging modalities such as ultrasound, computed tomography, magnetic resonance imaging, and positron emission tomography. This review advocates DXA incorporation into cardiovascular health assessments, emphasizing its crucial role in the early identification and management of Sub-CVD.

Are variants of the RBP4 gene associated with serum retinol-binding protein 4 concentrations and carotid intima-media thickness values in women with obesity?

INTRODUCTION

Several studies showed the correlation of retinol-binding protein 4 (RBP4) with increased cardiovascular risk - including higher values of carotid intima-media thickness (cIMT) - particularly in individuals with obesity.

OBJECTIVES

Our study aimed to investigate the impact of rs10882273; rs3758538; rs3758539, and rs7094671 RBP4 gene variants on RBP4 serum concentrations as well as cIMT values (a marker of subclinical atherosclerosis) among female patients with obesity.

PATIENTS AND METHODS

We recruited 74 women with obesity and 24 women without obesity as a study and control group, respectively. The genotypic and allelic frequencies of RBP4 gene variants were evaluated for associations with serum RBP4 and cIMT.

RESULTS

The median serum RBP4 concentrations were 20.30 µg/mL and 19.80 µg/mL in the patients and control group, respectively (p = 0.740). No significant differences were seen in cIMT values between the two studied groups (0.60 [0.50-1.00] vs. 0.60 ± 0.10 in the patient and control group, respectively); however, the results were close to reaching significance (p = 0.071), similar as in observed association of the minor haplotype AA for rs7084671 and rs375839 with female obesity (p = 0.0559). The correlation analysis showed no significant differences between RBP4 gene variants with serum RBP4 and cIMT.

CONCLUSIONS

According to our knowledge, this is the first study investigating the association between RBP4 gene variants and serum RBP4 and cIMT among Polish female patients with obesity. However, our results show that genetic variants rs10882273, rs3758538, rs3758539, and rs7094671 of the RBP4 gene are not associated with RBP4 serum concentrations or cIMT values among women with obesity.

Imaging Early Life Cardiovascular Phenotype

The growing epidemics of obesity, hypertension, and diabetes, in addition to worsening environmental factors such as air pollution, water scarcity, and climate change, have fueled the continuously increasing prevalence of cardiovascular diseases (CVDs). This has caused a markedly increasing burden of CVDs that includes mortality and morbidity worldwide. Identification of subclinical CVD before overt symptoms can lead to earlier deployment of preventative pharmacological and nonpharmacologic strategies. In this regard, noninvasive imaging techniques play a significant role in identifying early CVD phenotypes. An armamentarium of imaging techniques including vascular ultrasound, echocardiography, magnetic resonance imaging, computed tomography, noninvasive computed tomography angiography, positron emission tomography, and nuclear imaging, with intrinsic strengths and limitations can be utilized to delineate incipient CVD for both clinical and research purposes. In this article, we review the various imaging modalities used for the evaluation, characterization, and quantification of early subclinical cardiovascular diseases.

Nutrients and Dietary Approaches in Patients with Type 2 Diabetes Mellitus and Cardiovascular Disease: A Narrative Review

Cardiovascular disease (CVD) is the most common cause of morbidity and mortality in developed countries. The prevalence of CVD is much higher in patients with type 2 diabetes mellitus (T2DM), who may benefit from lifestyle changes, which include adapted diets. In this review, we provide the role of different groups of nutrients in patients with T2DM and CVD, as well as dietary approaches that have been associated with better and worse outcomes in those patients. Many different diets and supplements have proved to be beneficial in T2DM and CVD, but further studies, guidelines, and dietary recommendations are particularly required for patients with both diseases.

Low Levels of Serum Fetuin-A and Retinol-Binding Protein 4 Correlate with Lipoprotein Subfractions in Morbid Obese and Lean Non-Diabetic Subjects

Background: Fetuin-A and retinol-binding protein 4 (RBP4) are secreted as both hepatokine and adipokine. These are involved in insulin resistance, obesity-related dyslipidemia, and atherosclerosis. To date, correlations of circulating fetuin-A and RBP4 with lipoprotein subfractions as well as high-density lipoprotein (HDL)-linked proteins have not been entirely investigated in morbid obese and lean non-diabetic subjects. Methods: One-hundred obese non-diabetic patients (body mass index, BMI: 42.5 ± 8.1 kg/m²) along with 32 gender and age-matched normal weight controls (BMI: 24.5 ± 2.5 kg/m²) were enrolled in our study. Serum fetuin-A and RBP4 were measured by ELISA. Lipoprotein subfractions were distributed by Lipoprint gelelectrophoresis. Results: Serum fetuin-A and RBP4 were unexpectedly lower in obese patients (p < 0.01 and p < 0.01, respectively) compared to controls and correlated with each other (r = 0.37; p < 0.001). Fetuin-A had positive correlations with HDL-C (r = 0.22; p = 0.02), apolipoprotein AI (apoAI) (r = 0.33; p < 0.001), very-low density lipoprotein (VLDL) subfraction (r = 0.18; p = 0.05), and large HDL subfraction levels (r = 0.3; p = 0.001) but did not show correlation with carbohydrate parameters in all subjects. RBP4 correlated positively with HDL-C (r = 0.2; p = 0.025), apoAI (r = 0.23; p = 0.01), VLDL subfraction (r = 0.37; p < 0.001), intermediate HDL subfraction (r = 0.23; p = 0.01), and small HDL subfraction (r = 0.21; p = 0.02) concentrations, as well as C-peptide levels in overall participants. Backward stepwise multiple regression analysis showed that serum fetuin-A concentration is best predicted by RBP4 and large HDL subfraction. In model 2, VLDL subfraction was the independent predictor of serum RBP4 level. Conclusions: Our data may indicate a potential role of fetuin-A and RBP4 in impaired lipoprotein metabolism associated with obesity.

Is the Retinol-Binding Protein 4 a Possible Risk Factor for Cardiovascular Diseases in Obesity?

Although many preventive and treatment approaches have been proposed, cardiovascular disease (CVD) remains one of the leading causes of deaths worldwide. Current epidemiological data require the specification of new causative factors, as well as the development of improved diagnostic tools to provide better cardiovascular management. Excessive accumulation of adipose tissue among patients suffering from obesity not only constitutes one of the main risk factors of CVD development but also alters adipokines. Increased attention is devoted to bioactive adipokines, which are also produced by the adipose tissue. The retinol-binding protein 4 (RBP4) has been associated with numerous CVDs and is presumably associated with an increased cardiovascular risk. With this in mind, exploring the role of RBP4, particularly among patients with obesity, could be a promising direction and could lead to better CVD prevention and management in this patient group. In our review, we summarized the current knowledge about RBP4 and its association with essential aspects of cardiovascular disease-lipid profile, intima-media thickness, atherosclerotic process, and diet. We also discussed the RBP4 gene polymorphisms essential from a cardiovascular perspective.

Association between retinol-binding protein 4 concentrations and gestational diabetes mellitus (A1GDM and A2GDM) in different pregnancy and postpartum periods

Background

Gestational diabetes mellitus (GDM) can cause severe adverse effects on fetal and neonatal outcomes. The following study investigates the relationship between retinol-binding protein 4 (RBP4) and GDM in pregnant women with different grades (A1 and A2) and different gestational weeks.

Methods

In this retrospective study, 194 GDM patients (GDM group) and 67 normal glucose tolerance pregnant women (control group) were enrolled from 2014 to 2017. Elbow venous blood samples were collected from all subjects. Enzyme electrode method and enzyme linked immunosorbent assay (ELISA) were used for fasting plasma glucose (FPG) and RBP4/insulin levels (FINS) analysis, respectively.

Results

At middle pregnancy and late stage, FINS, insulin resistance index (HOMA-IR) and RBP4 were all significantly higher in the GDM group compared to control group (P<0.05). Higher HOMA-IR and RBP4 levels, and lower levels of FPG were observed at late stage than those middle pregnancy in the GDM group (P<0.05). Moreover, FINS and RBP4 gradually decreased from middle pregnancy and late stage after delivery in the GDM group. Levels of FINS and RBP4 in postpartum GDM group were higher than those in normal control group (P<0.05). The optimal cut-off value of RBP4 at middle pregnancy diagnostic GDM was 34.84 µg/mL with sensitivity of 79.4% and specificity of 79.1%. The OGTT0h, 2h in A2GDM group was higher than that in A1GDM group, but there was no difference in OGTT1h, age and FINS, RBP4 in both A1GDM and A2GDM group.

Conclusions

RBP4 is closely related to GDM, and its levels increases with the increase of gestational weeks, which may reflect the development of insulin resistance in GDM. RBP4 suggests that the impaired insulin function of GDM in pregnant women is still difficult to recover in the short term after delivery. Compared with OGTT1h, the increase in OGTT0h and 2h levels during middle pregnancy is more helpful for predicting the risk of developing A2GDM at late stage.

Vitamin A signaling and homeostasis in obesity, diabetes, and metabolic disorders

Much evidence has accumulated in the literature over the last fifteen years that indicates vitamin A has a role in metabolic disease prevention and causation. This literature proposes that vitamin A can affect obesity development and the development of obesity-related diseases including insulin resistance, type 2 diabetes, hepatic steatosis and steatohepatitis, and cardiovascular disease. Retinoic acid, the transcriptionally active form of vitamin A, accounts for many of the reported associations. However, a number of proteins involved in vitamin A metabolism, including retinol-binding protein 4 (RBP4) and aldehyde dehydrogenase 1A1 (ALDH1A1, alternatively known as retinaldehyde dehydrogenase 1 or RALDH1), have also been identified as being associated with metabolic disease. Some of the reported effects of these vitamin A-related proteins are proposed to be independent of their roles in assuring normal retinoic acid homeostasis. This review will consider both human observational data as well as published data from molecular studies undertaken in rodent models and in cells in culture. The primary focus of the review will be on the effects that vitamin A per se and proteins involved in vitamin A metabolism have on adipocytes, adipose tissue biology, and adipose-related disease, as well as on early stage liver disease, including non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH).

Evaluation of serum retinol-binding protein-4 levels as a biomarker of poor short-term prognosis in ischemic stroke

The aim was to investigate the relationship between retinol-binding protein 4 (RBP4) levels and short-term functional outcome, and to determine its possible role in acute ischemic stroke (AIS). In a prospective observational study, 299 first-ever AIS who were admitted to our hospital were included. Serum levels of RBP4 were assayed and severity of stroke was evaluated with the National Institutes of Health Stroke Scale (NIHSS) score on admission. The prognostic value of RBP4 to predict the poor outcome within 3 months was compared with the NIHSS and with other known outcome predictors. The median age of the included patients was 66 (interquartile range (IQR): 55-77) years and 155 (51.8%) were women. A poor functional outcome was found in 88 patients (29.4%), and significantly higher RBP4 values were found in poor outcomes rather than good outcomes patients (P<0.001). The poor outcomes distribution across the RBP4 quartiles ranged between 9.3% (first quartile) and 60.8% (fourth quartile). In multivariate models comparing the second(Q2), third, and fourth quartiles against the first quartile of the RBP4, RBP4 in Q3 and Q4 were associated with poor functional outcome, and increased risk of poor functional outcome by 144% (OR: 2.44; 95% confidence interval (CI): 1.22-5.03) and 602% (7.02; 3.11-12.24), respectively. Interestingly, RBP4 improved the NIHSS score (area under the curve (AUC) of the combined model, 0.79; 95% CI: 0.74-0.85; P<0.001). The data showed that elevated serum levels of RBP4 at admission were associated with severity and prognosis of AIS, suggesting that vitamin A metabolism or impaired insulin signaling could be involved.

Kidney function is associated with an altered protein composition of high-density lipoprotein

Patients with chronic kidney disease (CKD) exhibit a myriad of metabolic derangements, including dyslipidemia characterized by low plasma concentrations of high-density lipoprotein (HDL)-associated cholesterol. However, the effects of kidney disease on HDL composition have not been comprehensively determined. Here we used a targeted mass spectrometric approach to quantify 38 proteins contained in the HDL particles within a CKD cohort of 509 participants with a broad range of estimated glomerular filtration rates (eGFRs) (CKD stages I-V, and a mean eGFR of 45.5 mL/min/1.73m²). After adjusting for multiple testing, demographics, comorbidities, medications, and other characteristics, eGFR was significantly associated with differences in four HDL proteins. Compared to participants with an eGFR of 60 mL/min/1.73m² or more, those with an eGFR under 15 mL/min/1.73m² exhibited 1.89-fold higher retinol-binding protein 4 (95% confidence interval 1.34-2.67), 1.52-fold higher apolipoprotein C-III (1.25-1.84), 0.70-fold lower apolipoprotein L1 (0.55-0.92), and 0.64-fold lower vitronectin (0.48-0.85). Although the HDL apolipoprotein L1 was slightly lower among African Americans than among Caucasian individuals, the relationship to eGFR did not differ by race. After adjustment, no HDL-associated proteins associated with albuminuria. Thus, modest changes in the HDL proteome provide preliminary evidence for an association between HDL proteins and declining kidney function, but this needs to be replicated. Future analyses will determine if HDL proteomics is indeed a clinical predictor of declining kidney function or cardiovascular outcomes.

Association of retinol-binding protein 4 with metabolic syndrome in first-degree relatives of type 2 diabetic patients

Background:

Retinol-binding protein 4 (RBP4) is known to regulate lipid and glucose metabolism and insulin resistance. The influences of RBP4 on metabolic syndrome (MS) are still unclear. The purpose of this study is to evaluate the association between serum levels of RBP4 and MS components in first-degree relations of type 2 diabetic patients.

Materials and Methods:

This cross-sectional study was performed within the framework of the diabetes prevention project in Isfahan. This study has been conducted during 2012–2013. Seventy-eight subjects participate, with an average age of 43.20 ± 5.29 years. Weight, height, waist and hip circumferences, blood pressure (BP) of participants, fasting plasma glucose, hemoglobin A1c, total cholesterol, high-density lipoprotein cholesterol, triglyceride (TG), and serum RBP4 were measured from fasting blood sample taken from each participant after an overnight fast (12–14 h).

Results:

Systolic and diastolic BP were significantly higher in people in top median of RBP4 (11.8 ± 1.5 vs. 11.0 ± 1.2, P = 0.01 and 7.8 ± 1.0 vs. 7.3 ± 0.9, P = 0.03). Moreover, TG in people with high levels of RBP4 was higher compared with those with low levels of RBP4 (177.7 ± 97.6 vs. 138.7 ± 56.9, P = 0.02). People with low levels of RBP4 had significant greater hip circumferences (107.9 ± 7.5 vs. 104.3 ± 8.0, P = 0.04). There was no correlation between RBP4 and MS in crude model (odds ratio [OR]: 1.00, 0.95–1.05, P = 0.97). This null correlation remained after adjustment for body mass index, age, and physical activity (OR: 0.93, 0.91–1.07, P = 0.31).

Conclusion:

Although RBP4 levels were positively association with some risk factors of MS including hip circumference, TG, and systolic and diastolic BP, it does not seem to be a valuable marker for identification of the MS in the first relative degree of diabetic patients.