Retinol-binding Protein 4 Levels Research Articles

Retinol-binding protein 4 as a promising serum biomarker for the diagnosis and prognosis of hepatocellular Carcinoma

BackgroundThe prognosis of hepatocellular carcinoma (HCC) is universally poor. Early diagnosis plays a pivotal role in determining the outcome of HCC. MethodsWe employed a comparative proteomics approach to identify potential biomarkers and validated the application of retinol-binding protein 4 (RBP4) as a biomarker for HCC. RBP4 protein expression was examined in liver tissues from 80 HCC patients through immunohistochemical analysis. Serum RBP4 concentrations were measured by ELISA in a cohort comprising 290 HCC patients, matched 202 chronic hepatitis B patients and 269 healthy controls. Survival data were collected from HCC patients. The diagnostic and prognostic values of RBP4 were evaluated using receiver operating curve (ROC) analysis. ResultsThe validation results demonstrated a significant reduction in RBP4 levels in both liver tissues and serum samples from HCC patients. ROC analysis of the diagnostic value of RBP4 revealed an AUC of 0.879 (95 % CI: 0.854∼0.903) for HCC. When combined with AFP, the AUC increased to 0.919, with a sensitivity of 87.9 % and specificity of 80 %. Survival analysis revealed significantly reduced overall survival time in individuals with low-expression of RBP4 compared to those with high-expression. The joint prognostic model exhibited an AUC of 0.926 (95 % CI: 0.888∼0.964), which was significantly higher than that of AFP alone (AUC=0.809; P <0.0001). ConclusionsRBP4 shows a great potential as a biomarker with appreciable diagnostic value, complementing the AFP in HCC diagnosis. Additionally, it holds promise as a prognostic biomarker that, when integrated into a combined prognostic model, could greatly improve HCC prognosis efficiency.

MICRONUTRIENT STATUS (VITAMINS A AND D) AND ITS EFFECT ON THE SEVERITY OF THE COURSE OF COVID-19 IN CHILDREN

A strong immune response is important during recovery from COVID-19, and its status is infl uenced by several micronutrients. Vitamin D is important in regulating the immune response and protecting against respiratory infections. Vitamin A also has immunomodulatory eff ects, inhibiting viral replication and enhancing immune responses, thereby reducing morbidity and mortality from COVID-19. The aim of research was to study the levels of vitamins A, D, and retinol- binding protein 4 in children with COVID-19, and their associations with the severity of the disease.Material and Methods. 112 children aged 1 month to 18 years with COVID-19 confi rmed by polymerase chain reaction (PCR)in nasal swabs or by a positive serologic test (IgM and IgG or IgM). In all children, vitamin D levels were determined by thecolorimetric enzyme- linked immunosorbent assay (ELISA) using the Monobind test system. Vitamin A and retinol binding protein 4 (RBP4) levels were determined by the colorimetric enzyme- linked immunosorbent assay (ELISA) using the Elabscience test system. Statistical analysis was performed using Stat Plus (its 95 % confi dence interval (95 % CI) was calculated for the mean values, and the Kruskal- Wallis test (H-test) was used as the reliability criterion for checking the equality of the medians of several samples). The level of statistical signifi cance was set at P&lt;0.05). The study was conducted in accordance with the rules of patient safety and ethical principles of scientifi c medical research involving human subjects (2000). The permission to conduct this study was granted by the Bioethics Commission (Protocol No. 73, dated April 3, 2023). The parents (legal representatives) of the patients gave their written consent to the conduct of this study. This study is a fragment of research work «Optimizing the diagnosis of clinical and pathogenetic characteristics of the COVID-19 coronavirus infection in children with comorbid pathology and treatment features» (state registration No. 0123U100064, 2023-2025).Results. The mean age of the children was (7.04±5.75) years (95 % CI 5.96-8.12). According to the severity of the disease,57 children (50.89 %) had a mild course, 43 children (38.39 %) had a moderate course, and 12 children (10.72 %) had a severe course. The concentration of vitamin D in children with mild course of COVID-19 was 30.91 ng/ml, in children with moderate course – 29.10 ng/ml, in children with severe course – 22.42 ng/ml (Р&lt;0.05). The level of vitamin A also varied in children with diff erent severity of the disease: in mild COVID-19 it was 456.10 ng/ml, in moderate – 347.30 ng/ml, and in severe – 242.90 ng/ ml (Р &lt;0.001). At the same time, the level of retinol binding protein 4 was 30.66 ng/ml in mild disease, 33.07 ng/ml in moderate disease and 23.28 ng/ml in severe disease.Conclusions. Children with moderate and severe COVID-19 have signifi cantly lower levels of vitamins A, D, and RBP4compared to uninfected individuals. Vitamin A and RBP4 levels were age-dependent, and vitamin D levels did not show agerelated patterns. Lower levels of vitamins A and D are associated with higher levels of pro-infl ammatory markers – CRP,leukocytes and ESR.

Retinol binding protein 4 and type 2 diabetes: from insulin resistance to pancreatic β-cell function.

Retinol binding protein 4 (RBP4) is an adipokine that has been explored as a key biomarker of type 2 diabetes mellitus (T2DM) in recent years. Researchers have conducted a series of experiments to understand the interplay between RBP4 and T2DM, including its role in insulin resistance and pancreatic β-cell function. The results of these studies indicate that RBP4 has a significant influence on T2DM and is considered a potential biomarker of T2DM. However, there have also been some controversies about the relationship between RBP4 levels and T2DM. In this review, we update and summarize recent studies focused on the relationship between RBP4 and T2DM and its role in insulin resistance and pancreatic β-cell function to clarify the existing controversy and provide evidence for future studies. We also assessed the potential therapeutic applications of RBP4 in treating T2DM. A narrative review. Overall, there were significant associations between RBP4 levels, insulin resistance, pancreatic β-cell function, and T2DM. More mechanistic studies are needed to determine the role of RBP4 in the onset of T2DM, especially in terms of pancreatic β-cell function. In addition, further studies are required to evaluate the effects of drug intervention, lifestyle intervention, and bariatric surgery on RBP4 levels to control T2DM and the role of reducing RBP4 levels in improving insulin sensitivity and pancreatic β-cell function.

Adipokines in depressed women with and without adverse childhood experiences

BackgroundAdverse childhood experiences (ACE) elevate the risk of both major depressive disorder (MDD) and metabolic diseases. The underlying pathophysiology might include alterations of adipokine levels as a consequence of ACE. In this study, we used a full-factorial design to investigate the levels of select adipokines in women with ACE-only (n = 23), MDD-only (n = 27), ACE+MDD (n = 25) and healthy controls (HC, n = 29) to identify metabolic makers associated with vulnerability and resilience of developing MDD after ACE exposure. MethodsSerum levels of adiponectin, leptin, adiponectin-to-leptin (A/L) ratio, and retinol binding protein 4 (RBP4) were measured using enzyme-linked immunosorbent assay (ELISA). ResultsAdiponectin levels did not differ between groups. Individuals with vs. without MDD showed higher leptin serum concentrations. As predicted, A/L ratio indicated lower values in individuals with vs. without ACE. RBP4 showed a more nuanced pattern with reduced levels in the ACE-only and MDD-only groups compared to HC. Furthermore, the ACE-only group showed lower RBP4 concentrations compared to ACE+MDD. These results were not accounted by BMI or medication status. ConclusionOur results do not support the utility of adiponectin and leptin as predictors of vulnerability or resilience of developing MDD after ACE. In contrast, RBP4 might play a role in resilience towards the development of MDD following ACE. Further research on this more recently discovered adipokine seems warranted.

Reappraisal of serum retinol-binding protein as a surrogate marker for retinol and discovery of a novel retinol estimation formula

Background & AimsSerum retinol (ROH) is commonly used for population level assessment of vitamin A status. High-performance liquid chromatography (HPLC) is considered most accurate method for measuring ROH. However, with the technical difficulty of using HPLC for routine assays, serum retinol-binding protein (RBP) measured by immunological assays is expected to be a surrogate marker for ROH, with reports of a close correlation between serum RBP and ROH. Nevertheless, RBP is not commonly tested to assess vitamin A status with concerns over RBP alterations under various physiopathological conditions. Thus, we reappraised the extent to which RBP could be used as a surrogate marker in representative disorders that alter serum RBP levels. As a related marker, diagnostic utility of transthyretin (TTR) was also evaluated. MethodsTo evaluate the reliability of ROH and RBP assays, specimen stability was assessed in terms of (1) storage at 25, 4, −20, and −80 ºC for 1−28 days, (2) five-cycle freeze-thawing, and (3) fluorescent light exposure for 1−14 days. Sources of variation (sex, age, body mass index [BMI], and drinking habits) and reference intervals for ROH, RBP, and TTR were determined in 617 well-defined healthy individuals. To investigate the influence of disorders that affect serum RBP, patients with five diagnostic groups were enrolled: 26 with chronic kidney disease (CKD); 13 with various malignancies in advanced stages (AdM), 12 with acute bacterial infections (ABI), 6 with liver cirrhosis (LC), and 26 with simple obesity (BMI ≥ 27 kg/m2). ResultsThe stability of RBP and ROH in serum was confirmed under all conditions. In healthy individuals, serum ROH, RBP, and TTR were appreciably high in males with a slight increase in proportion to age and BMI. The major-axis regression line between RBP (x) and ROH (y) in healthy individuals was y = x, with a correlation coefficient of 0.986. In the LC, AdM, and ABI groups, similar strong correlations were observed; however, the regression lines were shifted slightly rightward from the healthy group line, indicating a positive bias in estimating ROH. Interestingly, the same analyses between TTR and ROH revealed similar strong linear relationships in all groups; however, the regression line of each group showed a leftward (opposite) shift from the healthy group line. Based on these observations, we developed a novel regression model composed of RBP and TTR, which proved to be accurate in estimating ROH, even under these pathological conditions. ConclusionsThe perfect RBP-ROH correlation in healthy individuals indicates the utility of RPB as a surrogate marker for ROH. Nevertheless, under RBP-altered conditions, a slight overestimation of ROH is inevitable. However, when the TTR was tested together, the bias can be corrected almost perfectly using the novel ROH estimation formula comprising RBP and TTR.

Retinol-binding protein 4 (RBP4) circulating levels and gestational diabetes mellitus: a systematic review and meta-analysis.

Gestational diabetes mellitus (GDM) is a prevalent condition where diabetes is diagnosed during pregnancy, affecting both maternal and fetal outcomes. Retinol-binding protein 4 (RBP4) is a circulating adipokine which belongs to the lipocalin family and acts as a specific carrier protein that delivers retinol (vitamin A) from the liver to the peripheral tissues. Growing data indicate that circulating RBP4 levels may positively correlate with GDM. Thus, this systematic review and meta-analysis aimed to investigate the potential relationship between circulating RBP4 levels and GDM when measured at various stages of pregnancy. MEDLINE, CINAHL, EMCARE, EMBASE, Scopus, and Web of Science databases were searched to identify studies comparing pregnant women with and without GDM, whose circulating RBP4 levels were measured in at least one pregnancy trimester. Findings were reported using standardized mean difference (SMD) and random-effects models were used to account for variability among studies. Furthermore, the risk of bias was assessed using the RoBANS tool. Out of the 34 studies identified, 32 were included in the meta-analysis (seven with circulating RBP4 levels measured in the first trimester, 19 at 24-28 weeks, and 14 at >28 weeks of pregnancy). RBP4 levels were statistically higher in the GDM group than in controls when measured during all these pregnancy stages, with the noted RBP4 SMD being 0.322 in the first trimester (95% CI: 0.126-0.517; p < 0.001; 946 GDM cases vs. 1701 non-GDM controls); 0.628 at 24-28 weeks of gestation (95% CI: 0.290-0.966; p < 0.001; 1776 GDM cases vs. 1942 controls); and 0.875 at >28 weeks of gestation (95% CI: 0.252-1.498; p = 0.006; 870 GDM cases vs. 1942 non-GDM controls). Significant study heterogeneity was noted for all three pregnancy timepoints. The present findings indicate consistently higher circulating RBP4 levels in GDM cases compared to non-GDM controls, suggesting the potential relevance of RBP4 as a biomarker for GDM. However, the documented substantial study heterogeneity, alongside imprecision in effect estimates, underscores the need for further research and standardization of measurement methods to elucidate whether RBP4 can be utilized in clinical practice as a potential GDM biomarker. PROSPERO (CRD42022340097: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022340097).

Vitamin A Positively Correlates with Secretory Immunoglobulin A: A Cross-Sectional Study in Omicron COVID-19 Outpatients.

Background: Respiratory tract infections remain among the leading causes of mortality worldwide. The COVID-19 pandemic has highlighted the importance of mucosal immunity in defending against infectious agents. Vitamin A is known to influence the production of secretory immunoglobulin A (SIgA) predominantly in the gut, where it is a critical component of the first line of defense on mucosal surfaces. Methods: This cross-sectional study, conducted 14 days post-positive COVID-19 diagnosis, aimed to determine the relationship between the nutritional status of vitamin A and SIgA levels in COVID-19 outpatients. Serum and saliva samples were collected. Vitamin A nutritional status was determined based on the assessment of dietary intake and the analysis of retinol-binding protein 4 (RBP4). SIgA levels were analyzed from salivary samples. In addition, serum antibodies were analyzed. Results: Dietary vitamin A intake and RBP4 levels positively correlated with SIgA. Patients with higher vitamin A intake showed higher SIgA/IgG1 and SIgA/IgG3 ratios, while those with higher RBP4 levels showed higher SIgA/IgM, SIgA/IgG1, and SIgA/IgG2 ratios. Conclusions: These findings underscore a significant correlation between vitamin A nutritional status and SIgA levels in COVID-19 outpatients, which may suggest the potential importance of maintaining optimal vitamin A levels for the prevention of viral infections.

Assessing the Impact of Bariatric Surgery on Retinol-Binding Protein 4 (RBP4): A Systematic Review and Meta-Analysis.

This study aimed to analyze changes in retinol-binding protein 4 (RBP4) levels before and after bariatric surgery in obese individuals. Bariatric surgery is a safe and effective treatment for morbid obesity, impacting molecules like RBP4. A systematic review and meta-analysis of 12 relevant studies were conducted, utilizing databases such as PubMed, Cochrane Central, Web of Science, and Scopus. Significant differences in RBP4, glucose, and BMI levels pre- and post-surgery were observed. Meta-regression analysis explored associations with age, pre-BMI, triglycerides, glucose, and post-insulin levels. Findings suggest RBP4 may improve insulin sensitivity after bariatric surgery, warranting further investigation as a potential pharmacotherapeutic target. These results highlight the importance of understanding RBP4's role in the context of bariatric surgery and its implications for improving metabolic health in obese individuals.

The Hepatokine RBP4 Links Metabolic Diseases to Articular Inflammation.

This study investigates the role of retinol binding protein 4 (RBP4) in an articular context. RBP4, a vitamin A transporter, is linked to various metabolic diseases. Synovial fluid RBP4 levels were assessed in crystalline arthritis (CA) patients using ELISA. RBP4's impact on articular cell types was analysed in vitro through RT-PCR and flow cytometry. Proteomic analysis was conducted on primary human osteoarthritis chondrocytes (hOACs). Synovial fluid RBP4 concentrations in CA patients correlated positively with glucose levels and negatively with synovial leukocyte count and were elevated in hypertensive patients. In vitro, these RBP4 concentrations activated neutrophils, induced the expression of inflammatory factors in hOACs as well as synoviocytes, and triggered proteomic changes consistent with inflammation. Moreover, they increased catabolism and decreased anabolism, mitochondrial dysfunction, and glycolysis promotion. Both in silico and in vitro experiments suggested that RBP4 acts through TLR4. This study identifies relevant RBP4 concentrations in CA patients' synovial fluids, linking them to hypertensive patients with a metabolic disruption. Evidence is provided that RBP4 acts as a DAMP at these concentrations, inducing robust inflammatory, catabolic, chemotactic, and metabolic responses in chondrocytes, synoviocytes, and neutrophils. These effects may explain RBP4-related metabolic diseases' contribution to joint destruction in various rheumatic conditions like CA.

Role of Retinol Binding Protein -4(RBP-4) and some Biochemical Parameters in Type II Diabetes Mellitus Patients

Diabetes is an important public health issue that adversely affects the lives of millions of individuals worldwide. RBP4 involvement in the pathogenesis of insulin resistance and type 2 diabetes. The aim of this study to assessment of role retinol binding protein -4 and other biochemical parameters in T2DM. Eighty eight participated in this study. Forty four T2DM, age between (40-60) years and forty four healthy control age between (40-55). there was a highly significant increase of FBS, HbA1C, TC, TG, LDL-C and VLDL-C, while a significant decreased of HDL-C between control and T2DM patients. There was a highly significant increase of RBP-4 level between different group (control and T2DM patients). Conclusion: Elevation of retinol in diabetic patients is considered a risk indicator for them with the early onset of cardiovascular disease, and this is a result of the continuous increase in the concentrations of sugar levels in the blood, and thus a defect in the metabolism of fats occurs, which leads to its rise, and this is an indicator of the entry of a diabetic patient with one of the complications, which is heart disease.

Clinical value of retinol binding protein, C-reactive protein and urine microalbumin in patients with chronic renal disease and ischemic cerebrovascular disease.

To explore the diagnostic value of retinol binding protein (RBP), C-reactive protein (CRP) and urine microalbumin (UMA) for ischemic cerebrovascular disease (ICD) in patients with chronic kidney disease (CKD). In this study, a total of 118 patients with CKD were selected and grouped into two groups: a group of patients who were complicated with ICD (CKD+ICD group, n=58), and a group of patients with CKD only (CKD group, n=60). Then, the patients in the CKD+ICD group were further classified into a good prognosis group and a bad prognosis group according their modified Rankin scale score at sixth months after discharge. Serum RBP, CRP and urine UMA levels were compared between the CKD group and CKD+ICD group. The diagnostic efficiency of serum RBP, CRP and urine UMA levels for ICD in patients with CKD was analyzed. The receiver operating characteristic (ROC) curve was used to assess their prognostic performance. Logistic regression analysis was used to evaluate the risk factors for poor prognosis of patients with CKD and ICD. The levels of RBP, CRP, and UMA in the CKD+ICD group were significantly higher than those in the CKD group (all P<0.05). RBP demonstrated the highest diagnostic accuracy and sensitivity for ICD in CKD patients, while CRP and UMA exhibited equivalent specificity, surpassing that of RBP. ROC curves showed that the areas under the curve (AUCs) of RBP and CRP were significantly greater than that of UMA (P<0.05) and there was no significant difference for AUCs between RBP and CRP. In addition, the levels of RBP, CRP and UMA in the poor prognosis group were significantly higher than those in the good prognosis group (all P<0.05). Logistic regression analysis showed that RBP, CRP and UMA were independent risk factors for the poor prognosis of patients with CKD and ICD (Odds ratios =2.507, 3.677 and 1.919, respectively; all P<0.05). The assessment of RBP, CRP and UMA is recommended for diagnosis of ICD in CKD patients. RBP, CRP and UMA are independent risk factors for poor prognosis of CKD patients with ICD.

Patient Characteristics Associated with Concurrent Klebsiella pneumoniae Infection and Severe Pulmonary Tuberculosis.

This study aims to investigate the clinical characteristics associated with concurrent Klebsiella pneu-moniae (K. pneumoniae) infection in hospitalized patients with severe pulmonary tuberculosis. A retrospective study was conducted on hospitalized severe pulmonary tuberculosis patients between January 2019 and December 2020. Among the 487 patients with severe pulmonary tuberculosis, a positive sputum culture for K. pneumoniae was reported in 76 patients (15.6%, 61 males and 15 females). Among these patients, 27 (35.5%) and 49 (64.5%) patients were with and without K. pneumoniae infection, respectively. Compared to patients without K. pneumoniae infection, patients with K. pneumoniae infection had higher mortality (16.3% vs. 40.7%, p = 0.02), and lower inhibitory/cytotoxic CD8 count (24.2 ± 9.9 vs. 17.8 ± 8.0, p = 0.02), complement C4 (0.3 ± 0.1 vs. 0.2 ± 0.1, p = 0.01), and retinol-binding protein level (32.2 ± 22.2 vs. 22.4 ± 11.8, p = 0.02). Furthermore, the acute Physiology and Chronic Health Evaluation II score was associated with the K. pneumoniae infection in severe pulmonary tuberculosis patients. It can be concluded that a significant number of severe pulmonary tuberculosis patients can have concurrent K. pneumoniae infection. Immunity, nutritional status, and disease severity are associated with the concurrent infection of K. pneumoniae in these patients.

Correlations of Serum Retinol-Binding Protein and Stromal Cell-Derived Factor-1 with Renal Function in Patients with Diabetic Kidney Disease.

The aim is to investigate the correlations of serum retinol-binding protein (RBP) and stromal cell-derived factor-1 (SDF-1) with renal function in patients with diabetic kidney disease (DKD). A total of 438 patients with type 2 diabetes mellitus (T2DM) treated from October 2017 to October 2020 were enrolled in this prospective study and divided into simple T2DM and DKD groups. According to urinary albumin-to-creatinine ratio (UACR), DKD patients were divided into moderate, severe, and nephrotic groups. They were assigned to one of the following categories of estimated glomerular filtration rate (eGFR): G1, G2, G3a, G3b, G4, and G5 stages. The correlations of RBP and SDF-1 with renal function were analyzed. The DKD group had a longer T2DM course and higher RBP, uric acid (UA), blood urea nitrogen (BUN), β2-microglobulin (β2-MG), serum creatinine (Scr) levels and UACR, and lower SDF-1 level and eGFR than those of simple T2DM group (p < 0.05). The areas under the receiver operating characteristic curves of RBP and SDF-1 for identifying DKD were 0.903 and 0.868, and the optimal cutoff values were 70.71 mg/L and 5.69 ng/mL, respectively. With increasing urinary albumin and clinical stage, RBP, UA, BUN, β2-MG and Scr levels and UACR significantly rose, while SDF-1 level and eGFR declined (p < 0.05). In patients with DKD, RBP was correlated positively with UACR, UA, BUN, β2-MG, and Scr (r = 0.764/0.787/0.693/0.577/0.801, p < 0.0001), and negatively with eGFR (r = -0.782, p < 0.0001). SDF-1 was correlated negatively with UACR, UA, BUN, β2-MG and Scr (r = -0.744/-0.794/-0.666/-0.605/-0.820, p < 0.0001), and positively with eGFR (r = 0.767, p < 0.0001). The multiple linear regression equation was RBP = 29.852 + 0.007 x UACR + 0.101 x UA + 0.497 x BUN + 0.034 x Scr-0.083 x eGFR (p < 0.001). RBP and SDF-1 can identify DKD in patients with T2DM, and the degree of renal function damage is correlated positively with RBP and negatively with SDF-1. Elevated levels of UA, BUN, Scr and UACR as well as reduced eGFR are risk factors for evaluating RBP.

Does Retinol-Binding Protein 4 (holo- and apo-RBP4) Increase or Remain Constant in Sera from Patients with Hypothyroidism?

Retinol-binding protein 4 (RBP4) is a retinol transporter in the blood plasma. Many diseases alter the plasma or serum levels of RBP4. Since serum RBP4 concentrations have been reported to decrease in hyperthyroidism, this study investigated whether serum RBP4 concentrations increased or remained constant in hypothyroidism. In sera from patients with hypothyroidism (n=71), hyperthyroidism (n=30), and healthy subjects (n=20), serum concentrations of RBP4 (sum of holo- and apo-RBP4), retinol, albumin, creatinine, and related constituents were measured, and RBP4/retinol molar ratio (as an index of apo-RBP4) and estimated glomerular filtration rate (eGFR) were calculated. The results showed that serum RBP4 concentrations tended to increase with decreasing free thyroxine concentrations, but there were no significant differences among patients with hypothyroidism, hyperthyroidism, and healthy subjects. When patients with hypothyroidism were subdivided by serum RBP4 level using 2.1 μmol/L cut-off value, patients with >2.1 μmol/L were revealed to be patients with older age having lower tri-iodothyronine, higher holo-RBP4, higher apo-RBP4, higher retinol, higher RBP4/retinol molar ratio, and lower eGFR than those in patients with <2.1 μmol/L. Multiple regression analysis showed significant associations between serum RBP4 levels and explanatory variables (retinol and eGFR). Although serum levels of RBP4 prior to the onset of renal dysfunction may affect the present concentrations, we conclude that the increase of serum RBP4 (both holo- and apo-RBP4) in patients with hypothyroidism was attributed to the decline in eGFR. In contrast, serum RBP4 concentration remained constant without renal dysfunction.

Retinol-Binding Protein 4 and Visfatin Levels in Patients with Periodontitis and Obesity/Overweight: A Systematic Review and Meta-Analysis.

Prior studies demonstrated an equivocal conclusion about the association between the level of retinol-binding protein 4 (RBP4)/visfatin and periodontitis patients with obesity. The aim of our study (Prospero ID: CRD42023469058) was to systematically review the available articles linking the biofluid levels of RBP4/visfatin to the comorbidity of periodontitis and obesity. Clinical trials were screened in accordance with specific inclusion criteria from seven databases up to November 2023. A quality assessment was performed with the Newcastle-Ottawa Scale and ROBINS-I tools for observational and interventional trials, respectively. The standard mean difference (SMD) with a 95% confidence interval (CI) related to the RBP4 level was recorded; the other indicators related to the visfatin level were measured via the mean difference (MD) with the corresponding 95% CI, and Fisher's Z transformation was measured to reveal the association using Review Manager 5.4. The current evidence was based on five observational studies and two interventional studies. All of them were included in the systematic review, and six of them were in the meta-analysis. Statistical analysis indicated that there was no significant difference in the circulating levels of RBP4 in the periodontitis patients with obesity or without, who were labeled as OP or NP, respectively (155 OP-107 NP: SMD = 1.38; 95% CI: -0.18-2.94, p = 0.08), as well as the periodontal healthy patients with a normal weight, who were labelled as NnP (116 OP-79 NnP: SMD = 6.76; 95% CI: -5.34-18.87, p = 0.27). Meanwhile, a significant higher level of serum visfatin was found in the OP patients than that of the NP (86 OP-45 NP: MD = 4.21; 95% CI: 2.65-5.77, p < 0.00001)/NnP (164 OP-88 NnP: MD = 13.02; 95% CI: 7.34-18.70, p < 0.00001) group. In addition, a positive association was observed between the serum RBP4 and body mass index/clinical attachment loss (CAL). And, then, there was a positive association between the serum visfatin and periodontal parameters, including the probing depth, CAL, and plaque index, as well as metabolic parameters, including the total cholesterol, triglycerides, fasting blood glucose, and low-density lipoprotein cholesterol. Here, the circulating RBP4 level was not independently related to the comorbidity of periodontitis and obesity, while serum visfatin was significantly associated with periodontitis and obesity. Notably, the positive association between circulating RBP4/visfatin and the periodontal parameters/metabolic parameters firmly suggested that the higher severity of the obese or periodontal status was associated with an elevated level of serum visfatin or RBP4 in the OP group. With more rigorous longitudinal research, the exact causations between RBP4/visfatin and the patients affected by obesity and periodontitis could be disentangled. RBP4 and visfatin might be novel, enlightening prospective bio-indexes for the targeted treatment of comorbidities.

Urinary orosomucoid and retinol binding protein levels as early diagnostic markers for diabetic kidney Disease

BackgroundDiabetic kidney disease (DKD) is the most common microvascular complication of diabetes, which has been a major cause of end-stage renal failure. Diagnosing diabetic kidney disease is important to prevent long-term kidney damage and determine the prognosis of patients with diabetes. In this study, we investigated the clinical significance of combined detection of urine orosomucoid and retinol-binding protein for early diagnosis of diabetic kidney disease.MethodsWe recruited 72 newly diagnosed patients with type 2 diabetes and 34 healthy persons from August 2016 to July 2018 at the First Affiliated Hospital of Henan Polytechnic University (Jiaozuo Second People’s Hospital). Using the Mogensen grading criteria, participants were classified as having diabetes or diabetic kidney disease, and healthy persons constituted the control group. Urine orosomucoid and retinol-binding protein levels were measured and correlated with other variables.ResultsWith the aggravation of renal damage, the level of urinary mucoid protein gradually increased. Urinary retinol-binding protein and microalbumin levels were significantly higher in the diabetes group than in control and nephropathy groups. Orosomucoid and retinol-binding protein might be independent risk factors for diabetes and diabetic kidney disease. Urinary orosomucoid significantly correlated with retinol-binding protein and microalbumin levels in the diabetic kidney disease group.ConclusionElevated urine orosomucoid and retinol-binding protein levels can be detected in the early stages of type 2 diabetic kidney disease. Both of these markers are important for diabetic kidney disease detection and early treatment.

Assessment of Circulating Retinol Binding Protein-4 Levels in Patients with Compound Heterozygosity for Hb S and β-Thalassemia

Background: Retinol Binding Protein-4 (RBP-4) is a member of the lipocalin family of proteins and the major transport protein of the hydrophobic molecule retinol, also known as vitamin A, in the circulation. Expression of RBP4 is highest in the liver, where most of the body's vitamin A reserves are stored as retinyl esters. For the mobilization of vitamin A from the liver, retinyl esters are hydrolyzed to retinol, which then binds to RBP-4 in the hepatocyte. After associating with transthyretin (TTR), the retinol/RBP-4/TTR complex is released into the bloodstream and delivers retinol to tissues via binding to specific membrane receptors. While, after its dissociation from TTR and retinol release, retinol-free apo-RBP4 in the circulation is filtrated by the kidney. More than 99% of that is reabsorbed by the proximal renal tubule, which renders urinary RBP-4 a highly sensitive marker for tubular dysfunction. We and other have shown previously that the patients with Sickle Cell Disease (SCD) have deficiencies or suboptimal levels of vitamin A, while recently (Br J Haematol. 2023;doi:10.1111/bjh.18862) higher urine RBP-4 in patients with SCD especially in those with persistent albuminuria but without an association of urine RBP-4 levels with estimated glomerular filtration rate (eGFR). In this context, we aimed to investigate the potential clinical significance of circulating plasma RBP-4 levels and its association with disease features in Caucasian patients with compound heterozygosity for HbS and β-thalassemia (HbS/β thal). Patients and Methods: Ninety Caucasian adult patients with HbS/β thal at steady phase were included in the study, while 22 apparently healthy individuals of similar age and gender served as controls. None of the patients was diabetic and has received any transfusions at least 6-monthes before enrollment in the study. RBP-4 concentration was measured with an immunoturbidimetric assay applied in an automated chemistry analyzer, along with hematologic, and series of blood chemistry parameters reflecting renal, cardiac and endothelial dysfunction. eGFR values were calculated using the CKD-EPI (Cystatin C and/or Creatinine equations). Results: We found that: a) Plasma RBP-4 levels were significantly lower in patients with HbS/β thal compared to controls, 30.5±2.7mg/L (Confidence Intervals (CI): 28.8;32.2mg/mL) vs 36.3±3.6mg/L (CI: 32.7;39.9mg/mL), p&amp;lt;0.003. The patients with β + genotypehave higher RBP-4 levels than those with β 0 genotype (p&amp;lt;0.05), whereas patients treated with hydroxycarbamide(50/90) are more likely to express higher RBP-4 levels, p-trend=0.06; b) RBP-4 levels in patients with HbS/β thal correlated positively with their age, body mass index (BMI) and Hb levels (r=0.264, p=0.012; r=0.334, p=0.001 and r=0.209, p&amp;lt;0.05, respectively; c) RBP-4 levels in patients with HbS/β thal correlated with total bilirubin, total cholesterol, triglycerides and uric acid (r=-0.452, p&amp;lt;0.001; r=0.395, p=0.004; r=0.292, p=0.015 and r=0.435, p&amp;lt;0.001, respectively); d) RBP-4 levels in patients with HbS/β thal correlated negatively with eGFR values rho=-0.360, p=0.003 and hs-CRP concentrations r=-0.309, p=0.004 and e) No correlations were found between RBP-4 levels with markers of cardiac and endothelial dysfunction such as High Sensitivity Troponin T, Growth Differentiation Factor-15, von Willebrand factor antigen, Α Disintegrin and Metalloproteinase with Thrombospondin Type 1 Motif 13 antigen and P-Selectin, as well as with number of vaso-occlusive crisis and mean pulmonary arterial pressure in the patients. Conclusions: These findings demonstrate a multifactorial role of RBP-4 in patients with HbS/β thal as the circulating levels of the protein correlate significantly with markers of erythropoiesis, inflammation and renal function. It is unclear of this study if RBP-4 has any specific functions in patients with HbS/β thal. However, RBP-4 should be more investigated in order to determine its clinical significance and in the case of sickle cell nephropathy both plasma and urine measurements should be considered.

Increased RBP4 and Asprosin Are Novel Contributors in Inflammation Process of Periodontitis in Obese Rats.

There is a significant comorbidity between obesity and periodontitis, while adipokines are pivotal in the immunoinflammatory process, which may play a role in this special relationship. We aimed to assess the effect of adipokines as mediators in the progression of periodontitis in obese Sprague Dawley rats. Rats were divided into four groups: normal body weight with and without periodontitis and obesity with and without periodontitis. Experimental obesity and periodontitis were induced by a high-fat diet or ligaturing, and the effect was measured using metabolic and micro-computed tomography analysis and histological staining. Compared with the other three groups, the group of periodontitis with obesity (OP) had the heaviest alveolar bone absorption, the largest increase in osteoclasts, the utmost inflammatory cell infiltration and the highest expressions of pro-inflammatory cytokines and nuclear factor-kappa B ligand (RANKL); meanwhile, its expression of the osteogenesis-related gene was the lowest among the four groups. The expressions of leptin, visfatin, resistin, retinol-binding protein 4 (RBP4) and asprosin were upregulated, while adiponectin was decreased significantly in OP. The strong positive associations between the periodontal or circulating levels of RBP4 (or asprosin) and the degree of alveolar resorption in experimental periodontitis and obese rats were revealed. The upregulated expression of inflammation biomarkers, the corresponding degradation in connective tissue and the generation of osteoclasts in periodontitis were activated and exacerbated in obesity. The elevated level of RBP4/asprosin may contribute to a more severe periodontal inflammatory state in obese rats.

Analysis of the association between serum levels of 25(OH)D, retinol binding protein, and Cyclooxygenase-2 and the disease severity in patients with diabetic foot ulcers.

Diabetic foot ulcers (DFUs) pose significant clinical challenges, representing severe complications in diabetes mellitus patients and contributing to non-traumatic amputations. Identifying reliable biomarkers can optimize early diagnosis and improve therapeutic outcomes. This study focused on evaluating the association between serum levels of 25-hydroxyvitamin D [25-(OH)D], Serum Retinol Binding Protein (RBP), and Cyclooxygenase-2 (COX-2) in elderly DFU patients. A retrospective study involving 240 participants, from March 2020 to March 2023. The participants were segmented into three cohorts: 80 with DFUs, 80 diabetic patients without DFUs, and 80 healthy controls. Serum concentrations of the three biomarkers were assayed using methods like enzyme-linked immunosorbent assay (ELISA), chemiluminescence immunoassay, and an automated biochemistry analyser. Comparisons were made both between groups and within the DFU group based on disease severity. Statistical analysis revealed significant differences in biomarker levels across the groups (p < 0.05). COX-2 and RBP concentrations were highest in the DFU group, followed by the non-DFU diabetic group, and lowest in the control group. Conversely, 25(OH)D levels were highest in the control group, followed by the non-DFU diabetic group, and lowest in the DFU group. Within the DFU group, RBP and COX-2 levels increased with disease severity, while 25(OH)D levels decreased. These variations were especially pronounced in patients with the most severe Wagner grading. A significant positive correlation was observed between disease severity and levels of RBP (r = 0.651, p < 0.05) and COX-2 (r = 0.356, p < 0.05). Conversely, a significant negative correlation was identified between disease severity and 25(OH)D levels (r = -0.658, p < 0.05). Assessing 25(OH)D, RBP, and COX-2 serum levels offers a promising tool for evaluating the severity and progression of DFUs. Monitoring these biomarkers can enrich our understanding of the metabolic and inflammatory pathways of the disease and potentially refine therapeutic strategies.

[Experimental study on the therapeutic effect and mechanism of erlotinib on non-proliferative diabetic retinopathy].

Objective: To investigate the therapeutic effect and mechanism of erlotinib, an epidermal growth factor receptor (EGFR) inhibitor, on non-proliferative diabetic retinopathy (NPDR). Methods: An experimental research was conducted. Human retinal Müller cells (RMC) were MIO-M1 cells from Moorfields Ophthalmology Hospital and the Institute of Ophthalmology at London University College. MIO-M1 cells were divided into normal, hypertonic, high glucose, high glucose+dimethyl sulfoxide (DMSO), high glucose+erlotinib 0.5 mmol/L, high glucose+erlotinib 1 mmol/L, and high glucose+erlotinib 2 mmol/L groups using a random number table method. Detection of the effect of erlotinib on the proliferation of MIO-M1 cells under high glucose conditions was performed by 5-ethynyl-2'-deoxyuridine (EdU) method. Western blotting (WB) was used to detect the effect of erlotinib on the activation markers of glial fibrillary acidic protein (GFAP) and glutamine synthetase (GS) protein levels in MIO-M1 cells under high glucose conditions. WB was used to detect the effect of erlotinib on the protein levels of nerve growth factor receptor (p75NTR), vimentin, and cell retinol binding protein (CRALBP) in RMC under high glucose conditions. MIO-M1 cells were divided into normal group, high glucose group, high glucose+DMSO group, and high glucose+erlotinib (1 mmol/L) group using random number table method. The effect of erlotinib on EGFR nuclear translocation under high glucose conditions was detected by cell immunofluorescence staining. Immunoprecipitation was used to detect the effect of erlotinib on the interaction between EGFR and transcription intermediate factor 2 (TIF2) in MIO-M1 cells under high glucose conditions. MIO-M1 cells were randomly divided into normal group, high glucose group, high glucose+DMSO group, high glucose+Myc-DDK empty body group, high glucose+erlotinib group, high glucose+erlotinib+human doublet protein group, high glucose+erlotinib+TIF2 plasmid group, and high glucose+erlotinib+human doublet protein+TIF2 plasmid group. Cell immunofluorescence staining was used to detect the effect of erlotinib on the binding of EGFR and TIF2 in MIO-M1 cells under high glucose conditions through the EGFR/TIF2 axis. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to detect the regulatory effect of EGFR and TIF2 binding on cyclin D1 transcription in MIO-M1 cells under high glucose conditions. The mouse model of diabetes retinopathy (DR) was constructed and divided into normal group, DR group, DR+DMSO group, DR+erlotinib 0.25 mg·kg-1·d-1 group, DR+erlotinib 0.5 mg·kg-1·d-1 group and DR+erlotinib 1 mg·kg-1·d-1 group. 25 mice in total, 5 in each group. Tissue immunofluorescence staining was used to detect the expression of RMC activation marker GFAP. The FITC-dextran injection experiment was used to detect the effect of erlotinib on retinal vascular leakage in a murine DR model. Results: Compared with the normal group (32.4%±3.0%), the proportion of EdU positive cells in RMC in the high glucose group (59.2%±3.8%) increased (P<0.001). Compared with the high glucose group (59.2%±3.8%), the proportion of EdU positive cells in the high glucose+1 mmol/L erlotinib group (37.6%±4.4%) decreased (P<0.001). Compared with the normal group, the expression of GFAP in RMC in the high glucose group increased (1 in the normal group, 2.27±0.11 in the high glucose group, P<0.001), while the expression of GS decreased (1 in the normal group, 0.32±0.03 in the high glucose group, P<0.001). 1 mmol/L erlotinib treatment reduced the expression of GFAP in RMC under high glucose conditions (1.32±0.13 and 2.27±0.11, respectively; P<0.001), and increased the expression of GS (0.71±0.06 and 0.32±0.03, respectively; P<0.001). The colocalization of EGFR and DAPI in RMC of the high glucose+1 mmol/L erlotinib group was lower than that of the high glucose group (52.2%±4.1% and 76.4%±5.7%, respectively; P<0.001). The expression of TIF2 or EGFR both increased while using EGF or TIF2 antibodies to precipitate TIF2 or EGFR under high glucose conditions compared to the normal group (1 in the normal group, 2.27±0.20 in the high glucose group, 2.17±0.21 in the EGFR, all P<0.05). And the expression of TIF2 (1.38±0.10) or EGFR (1.32±0.13) in the high glucose+erlotinib group was lower than that in the high glucose group (2.27±0.20) and the high glucose group (2.17±0.21) (all P<0.05). The colocalization of EGFR and TIF2 (17.2%±3.9%) and the mRNA level of Cyclin D1 (1.32±0.16) in the RMC of the high glucose+erlotinib group were lower than those in the high glucose group (54.6%±3.7% of EGFR and TIF2 colocalization ratio, 2.58±0.19 of Cyclin D1 mRNA level,all P<0.05). The high glucose+erlotinib+AREG (EGFR agonist) group, high glucose+erlotinib+Myc DDK-TIF2 plasmid group and high sugar+erlotinib+AREG+Myc-DDK-TIF2 plasmid group EGFR colocalization with TIF2 (colocalization ratios 24.1%±1.9%, 26.0%±2.3%, 35.3%±2.5%) and TIF2 mRNA levels (1.71±0.16, 1.72±0.18, 2.20±0.18). Compared with the high glucose+erlotinib group, The increases were statistically significant (all P<0.05). Compared to the normal group, the expression of GFAP in mouse retina tissue was increased in the DR group (1 in the normal group, 3.07±0.19 in the DR group, P<0.001), and 0.5 mg·kg-1·d-1 erlotinib (1.73±0.30) significantly reduced the expression of GFAP in the retina of DR group mice (P<0.05). Compared to the normal group (3.97±0.47), the DR group (23.13±2.15) showed an increase in fluorescein leakage, while the DR+erlotinib group (11.66±1.45) showed a significant decrease in leakage compared to the DR group (all P<0.05). Conclusions: Erlotinib inhibits the proliferation and activation of RMC induced by high glucose, inhibits the entry of EGFR into the nucleus, inhibits the binding of EGFR to TIF2 in RMC, and reduces the transcription of Cyclin D1 in RMC by inhibiting the interaction between EGFR and TIF2. At the same time, erlotinib inhibits the proliferation and activation of RMC in the mouse DR model, ameliorating retinal vascular leakage in mice. These results suggest that erlotinib inhibits the activation and proliferation of RMC by downregulating the EGFR/TIF2/Cyclin D1 pathway under high glucose conditions, thereby alleviating the progression of NPDR.