Enhanced excretion of vitamin D binding protein in type 1 diabetes: a role in vitamin D deficiency?

Urinary Vitamin D Binding Protein: A Marker of Kidney Tubular Dysfunction in Patients at Risk for Type 2 Diabetes

Context

Recent studies have reported elevated urinary vitamin D binding protein (uVDBP) concentrations in patients with diabetic kidney disease, although the utility of uVDBP to predict deterioration of kidney function over time has not been examined.

Objective

Our objective was to assess the association of uVDBP with longitudinal changes in kidney function.

Methods

Adults at-risk for type 2 diabetes from the Prospective Metabolism and Islet Cell Evaluation (PROMISE) study had 3 assessments over 6 years (n = 727). Urinary albumin-to-creatinine ratio (ACR) and estimated glomerular filtration rate (eGFR) were used as measures of kidney function. Measurements of uVDBP were performed with enzyme-linked immunosorbent assay and normalized to urine creatinine (uVDBP:cr). Generalized estimating equations (GEEs) evaluated longitudinal associations of uVDBP and uVDBP:cr with measures of kidney function, adjusting for covariates.

Results

Renal uVDBP loss increased with ACR severity at baseline. Individuals with normoalbuminuria, microalbuminuria, and macroalbuminuria had median log uVDBP:cr concentrations of 1.62 μg/mmol, 2.63 μg/mmol, and 2.48 μg/mmol, respectively, and ACR positively correlated with uVDBP concentrations (r = 0.37; P < .001). There was no significant association between uVDBP and eGFR at baseline. Adjusted longitudinal GEE models indicated that each SD increase both in baseline and longitudinal uVDBP:cr was significantly associated with higher ACR over 6 years (β = 30.67 and β = 32.91, respectively). Conversely, neither baseline nor longitudinal uVDBP:cr measures showed a significant association with changes in eGFR over time. These results suggest that loss of uVDBP:cr over time may be a useful marker for predicting renal tubular damage in individuals at risk for diabetes.

Vitamin D receptor rs3782905 and vitamin D binding protein rs7041 polymorphisms are associated with hepatocellular carcinoma susceptibility in cirrhotic HCV patients

BACKGROUND

The severity of chronic hepatitis C and susceptibility to hepatocellular carcinoma (HCC) are associated with genetic variations within vitamin D receptor (VDR) in several populations. This study aims to determine the significance of the VDRs (rs2228570, rs3782905, rs11568820) and DBP (rs7041) for the susceptibility to HCC in Egyptian patients with chronic HCV infection and their effect on the progression of liver cirrhosis to carcinogenesis.

METHODS

Single nucleotide polymorphisms (SNPs) VDR (rs2228570, rs3782905), and DBP rs7041 were genotyped using restriction fragment length-PCR (RFLP-PCR) technique and VDR rs11568820 was genotyped using single strand polymorphism PCR (SSP PCR). These SNPs genotypes, haplotypes and linkage disequilibrium analyses were examined in 299 Egyptian individuals (100 HCV-cirrhotic patients, 99 HCC- HCV patients, and 100 healthy controls).

RESULT

The VDR rs2228570 CC genotype, VDR rs3782905 GC and CC genotypes, and DBP rs7041 GG genotype are significantly higher in HCC. It is noteworthy that, VDR rs3782905 CC and DBP rs7041 TG genotypes are higher in HCV induced liver cirrhosis than with HCC progression in HCV infected patients. Furthermore, among patients, the relationship between these SNPs and smoking status, gender, and HCC susceptibility was reported.

CONCLUSION

Among the four investigated SNPs, there are associations between VDR rs3782905 and DBP rs7041 and the HCC progression in Egyptian patients chronically infected with HCV. These SNPs are considered as risk factors in HCV induced liver cirrhosis and HCC. The combinations of these SNPs with smoking status and gender are statistically linked to a high risk of HCC. Future research with a larger sample size of subjects with HCV infection is advised, because chronic liver disease induced by HCV infection is the primary cause of HCC in Egypt. We recommend screening of these SNPs for prediction of LC and HCC development in HCV infected patients, which may improve the used therapeutic protocol. These results suggest that VDR polymorphisms may be potential determinants for HCC susceptibility in Egyptian HCV patients.

Genetic influence on urinary vitamin D binding protein excretion and serum levels: a focus on rs4588 C>A polymorphism in the GC gene

Introduction

Vitamin D binding protein (VDBP) plays a crucial role in vitamin D transport and metabolism. The rs4588-A polymorphism of the GC gene, encoding VDBP, has been associated with altered serum VDBP and 25-hydroxyvitamin D (25OHD) levels. However, the mechanisms underlying these effects remain unclear. We aimed to investigate the relationship between urinary VDBP excretion and serum VDBP and 25OHD levels in individuals with and without the rs4588-A allele.

Methods

A cross-sectional study was conducted on 109 children (mean age: 11.96 years) to explore the impact of rs4588-A on vitamin D metabolism and urinary VDBP excretion. Biochemical analyses determined serum 25OHD and VDBP levels, and urinary VDBP-to-creatinine ratio (u-VDBP/Cr). Genotyping for rs4588 SNP was performed using LightSNiP assay. Statistical analyses included correlation, linear regression, and comparison between allele groups.

Results

Participants carrying the rs4588-A allele exhibited lower serum 25OHD levels compared to non-carriers (median (IQR): 11.85 (3.5) vs. 12.86 (4.9), p = 0.023). However, no statistically significant differences were observed in serum VDBP levels (126.34 ± 59.3 in rs4588-A vs. 136.49 ± 51.3 in non-rs4588-A, p = 0.141) or in u-VDBP/Cr (median (IQR): 0.4 (0.35) in rs4588-A vs. 0.386 (0.43) in non-rs4588-A, p = 0.189) between the two allele groups. A significant inverse correlation between u-VDBP/Cr and serum VDBP levels was found only in rs4588-A carriers (r = -0.367, p = 0.024). No such correlation was observed in non-carriers or the entire cohort. A linear regression analysis confirmed the impact of u-VDBP/Cr on serum VDBP levels in rs4588-A carriers (B = -0.269, t = -2.185, p = 0.035).

Conclusion

Individuals with the rs4588-A allele in the GC gene had lower serum 25OHD levels. An inverse correlation between urinary VDBP excretion and serum VDBP levels was observed, suggesting a partial role of the renal pathway in altered serum VDBP and 25OHD levels linked to the rs4588-A allele.

Performance of urinary vitamin D-binding protein in diabetic kidney disease: a meta-analysis

Objective: To systematically evaluate the correlation between urinary vitamin D-binding protein (VDBP) and diabetic kidney disease and to evaluate the relationship between urinary VDBP and the albumin-to-creatinine ratio (ACR), renal function indicators [estimate glomerular filtration rate (eGFR), creatinine (CR), blood urea nitrogen (BUN)] and glycaemic control indices [glycated hemoglobin (HbA1c), fasting plasma glucose (FPG)].Methods: We searched the CNKI, Wanfang, VIP, CBM, PubMed, Cochrane Library, Embase and Web of Science databases up to May 31, 2023, for relevant literature. RevMan 5.3 software was used for the meta-analysis.Results: Ultimately, 9 articles were included. Due to heterogeneity in the pooled results, the random-effects model was chosen. Meta-analysis results showed that the urinary VDBP concentrations in the normal albuminuria diabetes group were significantly higher than those in the healthy control group [SMD 1.52, 95% CI (0.84, 2.19), p < 0.00001]. The urinary VDBP concentrations in the microalbuminuria diabetes group were significantly higher than those in the normal albuminuria diabetes group [SMD 1.81, 95% CI (1.40, 2.21), p < 0.00001]. The urinary VDBP concentrations in the macroalbuminuria diabetes group were also significantly higher than those in the microalbuminuria diabetes group [SMD 1.51, 95% CI (1.05, 1.96), p < 0.00001]. In addition, urinary VDBP was positively correlated with the ACR, CR, BUN and HbA1c [Summary r = 0.73, 95% CI (0.54, 0.85), p < 0.0001; Summary r = 0.38, 95% CI (0.10, 0.61), p = 0.009; Summary r = 0.37, 95% CI (0.16, 0.55), p = 0.0008; Summary r = 0.40, 95% CI (0.13, 0.62), p = 0.005, respectively] and tended to be negatively correlated with the eGFR [Summary r = -0.64, 95% CI (-0.92, 0.10), p = 0.08] but was not significantly correlated with the FPG [Summary r = 0.16, 95% CI (-0.03, 0.33), p = 0.10]. Sensitivity analysis showed that our pooled results are robust.Conclusion: Urinary VDBP may be used as a novel biomarker for the early diagnosis of DKD and can be used to assess the severity of DKD.

Measurement of Urinary Gc-Globulin by a Fluorescence ELISA Technique: Method Validation and Clinical Evaluation in Septic Patients-A Pilot Study

A major complication of sepsis is the development of acute kidney injury (AKI). In case of acute tubular damage, Gc-globulin, a known serum sepsis marker is increasingly filtrated into the urine therefore, urinary Gc-globulin (u-Gc) levels may predict septic AKI. We developed and validated a competitive fluorescence ELISA method for u-Gc measurement. Serum and urine samples from septic patients were collected in three consecutive days (T1, T2, T3) and data were compared to controls. Intra- and interassay imprecisions were CV < 14% and CV < 20%, respectively, with a recovery close to 100%. Controls and septic patients differed (p < 0.001) in their u-Gc/u-creatinine levels at admission (T1, median: 0.51 vs. 79.1 µg/mmol), T2 (median: 0.51 vs. 57.8 µg/mmol) and T3 (median: 0.51 vs. 55.6 µg/mmol). Septic patients with AKI expressed higher u-Gc/u-creatinine values than those without AKI at T1 (median: 23.6 vs. 136.5 µg/mmol, p < 0.01) and T3 (median: 34.4 vs. 75.8 µg/mmol, p < 0.05). AKI-2 stage patients exhibited more increased u-Gc/u-creatinine levels at T1 (median: 207.1 vs. 53.3 µg/mmol, p < 0.05) than AKI-1 stage individuals. Moderate correlations (p < 0.001) were observed between u-Gc/u-creatinine and se-urea, se-creatinine, se-hsCRP, WBC, u-total protein, u-albumin, u-orosomucoid/u-creatinine, and u-Cystatin C/u-creatinine levels. U-Gc testing may have a predictive value for AKI in septic patients.

The Role of Polymorphism in the Endothelial Homeostasis and Vitamin D Metabolism Genes in the Severity of Coronary Artery Disease

Coronary artery disease (CAD) remains one of the leading causes of cardiovascular morbidity and mortality worldwide. The maintenance of endothelial homeostasis and vitamin D metabolism play an important role in CAD pathogenesis. This study aimed to determine the association of endothelial homeostasis and vitamin D metabolism gene polymorphism with CAD severity. A total of 224 low-risk patients (SYNTAX score ≤ 31) and 36 high-risk patients (SYNTAX score > 31) were recruited for this study. The serum level of E-, L- and P-selectins; endothelin; eNOS; 25OH; and 1.25-dihydroxy vitamin D was measured using an enzyme-linked immunosorbent assay (ELISA). Polymorphic variants in SELE, SELP, SELPLG, END1, NOS3, VDR and GC were analyzed using a polymerase chain reaction (PCR). We found no differences in the serum levels of the studied markers between high- and low-risk patients. Three polymorphic variants associated with CAD severity were discovered: END1 rs3087459, END1 rs5370 and GC rs2298849 in the log-additive model. Moreover, we discovered a significantly decreased serum level of 1.25-dihydroxy vitamin D in high-risk CAD patients with the A/A-A/G genotypes of the rs2228570 polymorphism of the VDR gene, the A/A genotype of the rs7041 polymorphism of the GC gene and the A/A genotype of the rs2298849 polymorphism of the GC gene.

Transcriptomic analysis reveal the responses of dendritic cells to VDBP

BACKGROUND

Vitamin D binding protein (VDBP) is an essential plasma carrier protein, which plays possible roles in reproductive health, disease and so on. However, the effects of VDBP on immunity have not been fully studied and the pertinent literatures remain very limited.

OBJECTIVE

In this study, we introduced the exogenous VDBP into DC2.4 and established a stable DC2.4/VDBP cell line to explore the role of this gene in immunity.

METHODS

Dendritic cells (DCs), as the most effective antigen presenting cells (APC) found so far, are directly involved in regulating some innate immunity. In order to evaluate the biological role of VDBP in DCs, we stably overexpressed VDBP in DCs, and conducted Cell Counting Kit‑8 (CCK-8 kit) and flow cytometry to detect changes in cell function. CCK-8 kit was used to monitor the viability of DCs after gene overexpression, and flow cytometry was used to detect changes in cell cycle distribution and apoptosis. Subsequently, in order to reveal the mechanism of VDBP regulating DCs, we adopted RNA sequencing (RNA-seq).

RESULTS

CCK-8 results revealed VDBP successfully inhibited viability of DCs. Besides, we found that overexpression of this gene greatly promoted apoptosis and obviously altered the cell cycle distribution of DCs in G1 and G2 phases. Moreover, RNA-seq was carried out and 151 differently expression genes (DEGs) were obtained. In addition, gene differential expression analysis showed that most of them were uniformly enriched in immunity-related pathways.

CONCLUSION

These results indicated that VDBP greatly repressed proliferation, facilitated apoptosis and changed cell cycle in DCs via altering the expression levels of gene associated with their cellular immunity.

Megalin and Vitamin D Metabolism—Implications in Non-Renal Tissues and Kidney Disease

Megalin is an endocytic receptor abundantly expressed in proximal tubular epithelial cells and other calciotropic extrarenal cells expressing vitamin D metabolizing enzymes, such as bone and parathyroid cells. The receptor functions in the uptake of the vitamin D-binding protein (DBP) complexed to 25 hydroxyvitamin D3 (25(OH)D3), facilitating the intracellular conversion of precursor 25(OH)D3 to the active 1,25 dihydroxyvitamin D3 (1,25(OH)2D3). The significance of renal megalin-mediated reabsorption of 25(OH)D3 and 1,25(OH)2D3 has been well established experimentally, and other studies have demonstrated relevant roles of extrarenal megalin in regulating vitamin D homeostasis in mammary cells, fat, muscle, bone, and mesenchymal stem cells. Parathyroid gland megalin may regulate calcium signaling, suggesting intriguing possibilities for megalin-mediated cross-talk between calcium and vitamin D regulation in the parathyroid; however, parathyroid megalin functionality has not been assessed in the context of vitamin D. Within various models of chronic kidney disease (CKD), megalin expression appears to be downregulated; however, contradictory results have been observed between human and rodent models. This review aims to provide an overview of the current knowledge of megalin function in the context of vitamin D metabolism, with an emphasis on extrarenal megalin, an area that clearly requires further investigation.

The association of vitamin D binding protein levels and genotypes with type 1 diabetes in the black South African population

BACKGROUND

Vitamin D deficiency and the vitamin D pathway have previously been associated with type 1 diabetes (T1D). The majority of vitamin D is transported through the blood bound to the vitamin D binding protein (VDBP). Two polymorphisms in the VDBP gene (rs4588 and rs7041) result in different VDBP variants and have been associated with T1D, however the results are not consistent. The association of VDBP levels and its polymorphisms with T1D have not been investigated in the black South African population. Therefore, this study aimed to determine whether rs4588, rs7041 or serum VDBP levels were associated with T1D in this population.

METHODS

Participants with type 1 diabetes and controls were recruited from the greater Johannesburg area, South Africa. Participants were genotyped for rs4588 and rs7041 using PCR-RFLP and serum VDBP levels were determined by ELISA.

RESULTS

There was no difference in VDBP allelic or genotypic frequencies between participants with T1D and controls (rs4588 C allele frequency 0.92 vs. 0.94; p = 0.390 and rs7041 T allele frequency 0.95 vs. 0.95; p = 0.890). In univariate analysis, the rs4588 CC genotype was associated with increased serum VDBP levels, however, this association was lost with multivariate analysis. The VDBP genotypes were not associated with any other study variables. In logistic regression analysis, higher VBDP levels were associated with T1D (OR: (95% CI): 6.58 (1.45-29.9); p = 0.015), and within a linear regression analysis, T1D disease status was found to be associated with 0.044 mg/ml higher VDBP levels (p = 0.028).

CONCLUSIONS

These data suggest that serum VDBP levels are positively associated with the presence of T1D in the African population. Whether VDBP lies in the causal pathway or its elevation is an effect of T1D is uncertain and requires further investigation.

Alterations in circulating levels of vitamin D binding protein, total and bioavailability of vitamin D in diabetic retinopathy patients

AIMS

This study aimed to investigate the association between circulating levels of vitamin D binding protein (VDBP) and its genotypes and diabetic retinopathy risk.

METHODS

This case-control study recruited 154 patients with type 2 diabetes mellitus; 62 with diabetic retinopathy (DR) and 92 without DR and diabetic nephropathy (DN). Circulating levels of 25-hydroxyvitamin D3 and VDBP levels were measured in the patients. The genotype and phenotype of VDBP were evaluated based on two common VDBP variations; rs7041 and rs4588.

RESULTS

Serum levels of VDBP were significantly lower in patients with DR than in patients without DR and/or DN (Ln-VDBP (μg/ml): 6.14 ± 0.92 vs. 6.73 ± 1.45, p = 0.001) even after adjustment for age, sex, body mass index, disease duration, estimated glomerular filtration rate (eGFR), HbA1C, insulin therapy profile, and serum levels of 25(OH)D. The distribution of VDBP phenotypes and genotypes in the two studied groups were nearly the same, and the distribution was similar to that of the general population.

CONCLUSIONS

In this study, we found the association between lower circulating levels of VDBP and risk of DR. However, the precise mechanism linking these two remains unknown. Further and more in-depth research is needed to find out the underlying causes of the relationship.

Free and Bioavailable Vitamin D Levels of Patients with Type 1 Diabetes Mellitus and Association with Bone Metabolism

Aim

Vitamin D deficiency is known to be associated with metabolic bone diseases. The aim of this study is to evaluate vitamin D and calculated free and bioactive vitamin D levels of type 1 diabetic patients and to evaluate the association with bone turnover markers.

Method

This cross-sectional study includes 60 patients admitted to endocrinology outpatient clinic with diagnosis of type 1 diabetes mellitus and 60 controls. Weight, height and waist circumference were recorded and blood samples were taken for measurement of 25-hydroxyvitamin D (25(OH)D), vitamin D binding protein (VDBP), osteocalcin, bone alkaline phosphatase (bone-ALP), c-telopeptide. Free and bioavailable vitamin D levels were calculated with formula.

Results

Vitamin D levels of type 1 diabetic patients were significantly higher (p = 0.01). Parathormone levels of the group with vitamin D level under 20 ng/ml was significantly higher (p = 0.029). VDBP levels were similar in both groups. Correlation analysis of free and bioavailable vitamin D level with osteocalcin, c-telopeptide, bone alkaline phosphatase revealed only a weak significant correlation between free vitamin D and osteocalcin (r = -0.201; p = 0.028). A negative correlation was determined between 25(OH)D and parathormone levels (r = -0.294; p < 0.005). Serum osteocalcin, bone alkaline phosphatase and c-telopeptide levels of control group were significantly higher.

Conclusion

25(OH)D levels of the study population was extremely low. The measurement of VDBP and calculated free and bioactive vitamin D levels did not show a better correlation with bone turnover markers according to 25(OH)D levels.

To the Question of Vitamin D Network in Type 1 Diabetes and Diabetic Nephropathy in Children Nursed in Ukrainian Endocrinology Unit

Background

Vitamin D deficiency is a great problem worldwide. Vitamin D plays an essential role in calcium and bone metabolism. Diabetic nephropathy (DN) is a dangerous kidney-related complication of type 1 diabetes (T1D).

Aim of the study

To evaluate levels of Vitamin D3 in pediatric patients with T1D and DN; to study the dependence between the Vitamin D level and main clinical and laboratory parameters of the disease, that is, duration, complications episodes, albuminuria levels, glomerular filtration rate (GFR).

Material and methods

A survey of 72 children with T1D and DN aged 3–17 years was done. Complex examination including conventional methods (physical examination, blood pressure measurement, blood tests, study of urinary sediment, renal ultrasound, etc.) was done for all patients. Data was processed using GraphPad Prism 9.0 Software for Windows (USA, San Diego, CA). p-values <.05 were considered statistically significant.

Results

Majority of patients from T1D group have normal value of Vitamin D, only 27.7% of children have Vitamin D insufficiency. In contrast, in children from DN group only 16.7% of children have Vitamin D insufficiency and 83.3% have Vitamin D deficiency. Vitamin D serum level negatively correlates with disease duration and albuminuria level in the group with DN. Serum levels of Vitamin D positively correlate with GFR in patients with T1D. Patients with DN who had a duration of T1D for 10 years and more have a higher progression rate to Vitamin D deficiency as compared to those who have a T1D duration of less than 10 years.

Conclusions

The authors conclude that Vitamin D has a direct relationship with functional disorders with DN, that is, albuminuria, GFR, kidney function. Further investigations of Vitamin D supplementation on different stages of the ND development and progression are needed.

Free, bioavailable 25-hydroxyvitamin D levels and their association with diabetic ketoacidosis in children with type 1 diabetes at diagnosis

BACKGROUND

Considering the roles of 25-hydroxyvitamin D (25OHD) in glucose homeostasis and immune modulation, vitamin D deficiency may be related to the development of type 1 diabetes (T1DM) and diabetic ketoacidosis (DKA). We evaluated the total, free, bioavailable 25OHD levels and vitamin D binding protein (VDBP) levels and genotypes between T1DM patients and controls.

METHODS

This retrospective, cross-sectional study included 84 children with T1DM (38 boys and 46 girls, 8.0 ± 3.6 years) and 1:1 age- and sex-matched healthy controls. A multiplex liquid chromatography-tandem mass spectrometry-based assay was used to simultaneously measure vitamin D metabolites.

RESULTS

Patients with T1DM had lower levels of total 25OHD (16.3 ± 5.1 vs. 19.9 ± 6.5 ng/mL, P< 0.001) and VDBP (146.0 ± 27.8 vs. 224.9 ± 36.1 µg/mL, P = 0.001), but higher free 25OHD (8.0 ± 2.5 vs. 6.5 ± 2.3 pg/mL, P< 0.001) than controls. Patients who presented with DKA had lower levels of 25OHD in the total (15.0 ± 4.6 vs. 17.6 ± 5.2 ng/mL, P = 0.020), free (7.5 ± 2.6 vs. 8.4 ± 2.4 pg/mL, P = 0.059), and bioavailable (2.3 ± 0.9 vs. 2.8 ± 0.8 ng/mL, P = 0.014) forms than those without DKA at the T1DM diagnosis. The lower the total, free, and bioavailable 25OHD levels at diagnosis, the lower the pH and HCO3-. The proportions of the VDBP genotypes did not differ between the patients and controls.

CONCLUSION

Patients with T1DM had higher levels of free 25OHD than healthy children, despite lower levels of total 25OHD. However, patients with DKA exhibited lower levels of bioavailable 25OHD than those without DKA at the T1DM diagnosis. The lower the concentrations of free and bioavailable 25OHD, the more severe the acidosis at the initial T1DM presentation.

Early detection of diabetic nephropathy in patient with type 2 diabetes mellitus: A review of the literature

Type 2 diabetes mellitus is a pathology of heterogeneous etiology characterized by hyperglycemia resulting from lack of insulin action, insulin secretion, or both, and the population with diabetes mellitus is predicted to be about 439 million worldwide by 2030. Prolong diabetes has been related with microvascular complications especially diabetic nephropathy. DN is the most common complication of type 2 diabetes mellitus, and it is the leading cause of end-stage renal disease worldwide. It is crucial to diagnose patients who are more sensible to develop DN for better control of the process of disease. Several factors and mechanisms contribute to the development and outcome of diabetic nephropathy. Microalbuminuria is an early marker of DN and use it as a routine for screening, but the renal damages may be happening even without microalbuminuria. There are several significant kidney damage and disease biomarkers which helps in early detection of DN. An early biomarker may allow earlier diagnosis, treatment reduces DN prevalence and slows DN progression. Therefore, this review focuses on laboratory biomarkers that are earlier, more validation of an early and specific biomarker could potentially make it possible for early diagnosis, treatment, and retardation of progression of diabetic nephropathy.

Secondary hyperparathyroidism and adverse health outcomes in adults with chronic kidney disease

Background

Secondary hyperparathyroidism (sHPT) develops frequently in patients with chronic kidney disease (CKD). However, the burden and long-term impact of sHPT on the risk of adverse health outcomes are not well studied.

Methods

We evaluated all adults receiving nephrologist care in Stockholm during 2006–11 who were not undergoing kidney replacement therapy and had not developed sHPT. Incident sHPT was identified by using clinical diagnoses, initiated medications or two consecutive parathyroid hormone (PTH) measurements ≥130 pg/mL. We characterized sHPT incidence by estimated glomerular filtration rate (eGFR) strata, evaluated clinical predictors and quantified the association between incident sHPT (time-varying exposure) and the risk of fractures, CKD progression, major adverse cardiovascular events (MACEs) and death.

Results

We identified 2556 adults with CKD Stages 1–5 (mean age 66 years, 38% women), of whom 784 developed sHPT during follow-up. The incidence of sHPT increased with advancing CKD: from 57 cases/1000 person-years in CKD Stage G3 to 230 cases/1000 person-years in Stage G5. In multivariable analyses, low eGFR was the strongest sHPT predictor, followed by young age, male sex and diabetes. Incident sHPT was associated with a 1.3-fold (95% confidence interval 1.1–1.8) increased risk of death, a 2.2-fold (1.42–3.28) higher risk of MACEs, a 5.0-fold (3.5–7.2) higher risk of CKD progression and a 1.3-fold (1.5–2.2) higher risk of fractures. Results were consistent in stratified analyses and after excluding early events.

Conclusions

Our findings illustrate the burden of sHPT in advanced CKD and highlight the susceptibility for adverse outcomes of patients developing sHPT. This may inform clinical decisions regarding pre-sHPT risk stratification, PTH monitoring and risk-prevention strategies post-sHPT development.

Vitamin K and D Supplementation and Bone Health in Chronic Kidney Disease-Apart or Together?

Vitamin K (VK) and vitamin D (VD) deficiency/insufficiency is a common feature of chronic kidney disease (CKD), leading to impaired bone quality and a higher risk of fractures. CKD patients, with disturbances in VK and VD metabolism, do not have sufficient levels of these vitamins for maintaining normal bone formation and mineralization. So far, there has been no consensus on what serum VK and VD levels can be considered sufficient in this particular population. Moreover, there are no clear guidelines how supplementation of these vitamins should be carried out in the course of CKD. Based on the existing results of preclinical studies and clinical evidence, this review intends to discuss the effect of VK and VD on bone remodeling in CKD. Although the mechanisms of action and the effects of these vitamins on bone are distinct, we try to find evidence for synergy between them in relation to bone metabolism, to answer the question of whether combined supplementation of VK and VD will be more beneficial for bone health in the CKD population than administering each of these vitamins separately.

Evaluation of Vitamin D Metabolism in Patients with Type 1 Diabetes Mellitus in the Setting of Cholecalciferol Treatment

In this prospective controlled study, we examined 25 adults with adequately controlled (HbA1c level < 8.0%) type 1 diabetes mellitus (T1DM) and 49 conditionally healthy adults, intending to reveal the diversity of vitamin D metabolism in the setting of cholecalciferol intake at a therapeutic dose. All patients received a single dose (150,000 IU) of cholecalciferol aqueous solution orally. Laboratory assessments including serum vitamin D metabolites (25(OH)D₃, 25(OH)D₂, 1,25(OH)₂D₃, 3-epi-25(OH)D₃ and 24,25(OH)₂D₃), free 25(OH)D, vitamin D-binding protein (DBP) and parathyroid hormone (PTH) as well as serum and urine biochemical parameters were performed before the intake and on Days 1, 3 and 7 after the administration. The studied groups had no significant differences in baseline parameters except that the patients with diabetes showed higher baseline levels of free 25(OH)D (p < 0.05). They also lacked a correlation between the measured and calculated free 25(OH)D in contrast to the patients from the control group (r = 0.41, p > 0.05 vs. r = 0.88, p < 0.05), possibly due to the glycosylation of binding proteins, which affects the affinity constant for 25(OH)D. The elevation of vitamin D levels after the administration of cholecalciferol was comparable in both groups, with slightly higher 25(OH)D₃ levels observed in the diabetes group throughout the study since Day 1 (p < 0.05). Overall, our data indicate that in patients with adequately controlled T1DM 25(OH)D₃ levels and the therapeutic response to cholecalciferol is similar to that in healthy individuals.

Executive summary of clinical practice guide on fracture risk in lifestyle diseases

Accumulating evidence has shown that patients with lifestyle diseases such as type 2 diabetes mellitus, chronic kidney disease, and chronic obstructive pulmonary disease are at increased risk of osteoporotic fracture. Fractures deteriorate quality of life, activities of daily living, and mortality as well as a lifestyle disease. Therefore, preventing fracture is an important issue for those patients. Although the mechanism of the lifestyle diseases-induced bone fragility is still unclear, not only bone mineral density (BMD) reduction but also bone quality deterioration are involved in it. Because fracture predictive ability of BMD and FRAX^® is limited, especially for patients with lifestyle diseases, the optimal management strategy should be established. Thus, when the intervention of the lifestyle diseases-induced bone fragility is initiated, the deterioration of bone quality should be taken into account. We here review the association between lifestyle diseases and fracture risk and proposed an algorism of starting anti-osteoporosis drugs for patients with lifestyle diseases.

Association between vitamin D metabolites, vitamin D binding protein, and proteinuria in dogs

BACKGROUND

Proteinuria has been associated with progression of renal disease and increased morbidity and mortality in dogs and people. In people, proteinuria also has been associated with hypovitaminosis D. Little is known about the relationship between vitamin D metabolism and proteinuria in dogs.

OBJECTIVES

To further elucidate vitamin D status in dogs with protein-losing nephropathy (PLN) and minimal to no azotemia. We hypothesized that vitamin D metabolites would be lower in dogs with PLN compared to healthy dogs.

ANIMALS

Twenty-three client-owned adult dogs with PLN and 10 healthy control dogs.

METHODS

Serum 25-hydroxyvitamin D (25[OH]D), 1,25-dihydroxyvitamin D (1,25[OH]₂ D), 24,25-dihydroxyvitamin D (24,25[OH]₂ D), serum vitamin D binding protein (VDBP), and urine 25(OH)D concentrations were measured.

RESULTS

Compared to healthy dogs, dogs with PLN had lower concentrations of all vitamin D metabolites (P < .01). Correlations (rho; 95% confidence interval [CI]) in dogs with PLN are reported. Serum 25(OH)D and 24,25(OH)₂ D concentrations were positively correlated with albumin (r = 0.47; 0.07-0.74), and 24,25(OH)₂ D was negatively correlated with urine protein-to-creatinine ratio (UPC; r = -0.54; -0.78 to -0.16). Urine 25(OH)D-to-creatinine ratio was negatively correlated with serum albumin concentration (r = -0.77; -0.91 to -0.50) and positively correlated with UPC (r = 0.79; 0.53-0.91). Serum VDBP concentration was positively correlated with serum albumin concentration (r = 0.53; 0.05-0.81).

CONCLUSIONS AND CLINICAL IMPORTANCE

Dogs with PLN have decreased serum concentrations of vitamin D metabolites. Urine 25(OH)D-to-creatinine ratio and UPC are correlated in PLN dogs. Future studies are needed to assess additional management strategies for dogs with PLN.

Association Between Vitamin D and Uric Acid in Adults: A Systematic Review and Meta-Analysis

Association between vitamin D and uric acid is complex and might be bidirectional. Our study aimed to determine the bidirectional association between vitamin D and uric acid in adults. Using MEDLINE via PubMed and Scopus, we systematically searched for observational or interventional studies in adults, which assessed the association between serum vitamin D and serum uric acid, extracted the data, and conducted analysis by direct and network meta-analysis. The present review included 32 studies, of which 21 had vitamin D as outcome and 11 had uric acid as outcome. Meta-analysis showed a significant pooled beta coefficient of serum uric acid level on serum 25(OH)D level from 3 studies of 0.512 (95% confidence interval: 0.199, 0.825) and a significant pooled odds ratio between vitamin D deficiency and hyperuricemia of 1.496 (1.141, 1.963). The pooled mean difference of serum 25(OH)D between groups with hyperuricemia and normouricemia was non-significant at 0.138 (-0.430, 0.707) ng/ml, and the pooled mean difference of serum uric acid between categories of 25(OH)D were also non-significant at 0.072 (-0.153, 0.298) mg/dl between deficiency and normal, 0.038 (-0.216, 0.292) mg/dl between insufficiency and normal, and 0.034 (-0.216, 0.283) mg/dl between deficiency and insufficiency. In conclusion, increasing serum uric acid might be associated with increasing 25(OH)D level, while vitamin D deficiency is associated with hyperuricemia. These reverse relationships should be further evaluated in a longitudinal study.

Lower serum 25-hydroxyvitamin D levels are associated with impaired glomerular filtration rate in type 2 diabetes patients

BACKGROUND

25-Hydroxyvitamin D [25(OH)D] deficiency has been implicated as a possible risk factor for the onset and progression of diabetes kidney disease (DKD). The aim of this study was to evaluate the interaction between levels of 25(OH)D and DKD in type 2 diabetes mellitus (DM) patients.

METHODS

Cross-sectional design, outpatient type 2 DM. Glomerular filtration rate (GFR) was measured by 51Cr-EDTA and estimated by Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), urinary albumin excretion (UAE) by immunoturbidimetry, and 25(OH)D by chemiluminescence. Receiver operating characteristic (ROC) curve analysis and generalized linear model (Poisson robust regression estimator) were used to assess the interaction between 25(OH)D levels and renal function.

RESULTS

A total of 114 type 2 DM patients aged 60 ± 10 years, 49 males (43%), DM duration 22 ± 10 years, with GFR > 60 ml/min/1.73 m2 were evaluated. Patients with GFRs 60-90 (n = 50) had significantly lower 25(OH)D levels than individuals with GFRs > 90 ml/min/1.73 m2 (n = 64), respectively 40 ± 20 versus 48 ± 20 nmol/l, p = 0.027. This difference was more pronounced for older individuals (39 ± 20 versus 54 ± 23 nmol/l, respectively), and Poisson robust regression disclosed that lower 25(OH)D [Poisson regression (PR) = 0.989, confidence interval (CI): 0.978-0.999, p = 0.034], and advanced age (PR = 1.050, CI: 1.007-1.096, p = 0.023) were significantly associated with the lower GFR category, adjusted for seasons. ROC curve analysis showed that the cutoff point of 25(OH)D of 41 nmol/l was associated with lower GFR [area under the curve (AUC) = 0.694, p = 0.009]. CKD-EPI estimated GFR (eGFR) was not associated with 25(OH)D in any analysis. There was no difference in 25(OH)D levels between patients with elevated UAE as compared with normoalbuminuric ones (44 ± 21 versus 46 ± 19 nmol/l, p = 0.587).

CONCLUSION

Lower levels of 25(OH)D are associated with decreased GFR in patients with type 2 DM, especially in older patients, with no evidence of interaction with UAE levels.

Vitamin D deficiency 2.0: an update on the current status worldwide

Vitamin D testing and the use of vitamin D supplements have increased substantially in recent years. Currently, the role of vitamin D supplementation, and the optimal vitamin D dose and status, is a subject of debate, because large interventional studies have been unable to show a clear benefit (in mostly vitamin D replete populations). This may be attributed to limitations in trial design, as most studies did not meet the basic requirements of a nutrient intervention study, including vitamin D-replete populations, too small sample sizes, and inconsistent intervention methods regarding dose and metabolites. Vitamin D deficiency (serum 25-hydroxyvitamin D [25(OH)D] < 50 nmol/L or 20 ng/ml) is associated with unfavorable skeletal outcomes, including fractures and bone loss. A 25(OH)D level of >50 nmol/L or 20 ng/ml is, therefore, the primary treatment goal, although some data suggest a benefit for a higher threshold. Severe vitamin D deficiency with a 25(OH)D concentration below <30 nmol/L (or 12 ng/ml) dramatically increases the risk of excess mortality, infections, and many other diseases, and should be avoided whenever possible. The data on a benefit for mortality and prevention of infections, at least in severely deficient individuals, appear convincing. Vitamin D is clearly not a panacea, and is most likely efficient only in deficiency. Given its rare side effects and its relatively wide safety margin, it may be an important, inexpensive, and safe adjuvant therapy for many diseases, but future large and well-designed studies should evaluate this further. A worldwide public health intervention that includes vitamin D supplementation in certain risk groups, and systematic vitamin D food fortification to avoid severe vitamin D deficiency, would appear to be important. In this narrative review, the current international literature on vitamin D deficiency, its relevance, and therapeutic options is discussed.

Muscle and bone parameters in underprivileged Indian children and adolescents with T1DM

BACKGROUND

The incidence of Type 1 diabetes mellitus (T1DM) is increasing and sarcopenia and osteoporosis have been reported to be associated with long standing diabetes. There is scarcity of data on bone health status of children with T1DM. Our aim was to assess bone health parameters [by Dual energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT)] and muscle strength (by hand grip) in underprivileged Indian children with T1DM.

MATERIAL AND METHODS

A cross sectional, observational study was conducted in underprivileged children with diabetes attending the out patient clinic for T1DM at a tertiary care hospital. Children with T1DM with disease duration more than 1 year were included in the study. Age and gender matched controls were also enrolled. Data on age, gender, disease duration, anthropometric parameters and HbA1c were collected. Bone mineral density (BMD) was assessed by dual energy X-ray absorptiometry (Lunar iDXA) and peripheral quantitative computed tomography (pQCT, Stratec XCT 2000) and muscle strength by handgrip. Data were analysed using SPSS 25.0.

RESULTS

251 children with T1DM and 250 age gender matched controls were studied. Mean age of T1DM children was 10.8 ± 4.3yrs (controls 10.3 ± 3.6). Mean HbA1C was 9.7 ± 2.1%. The total body less head areal BMD (TBLH aBMD) and lumbar spine bone mineral apparent density (LSBMAD) Z-scores were significantly lower in children with T1DM (-1.5 ± 1.3, -1.3 ± 1.6 respectively) as compared to controls (-0.5 ± 1.3, -0.64 ± 1.5 respectively) (p < 0.05 for both). Z-scores for trabecular and total density (vBMD) were significantly lower in patients with T1DM (-0.7 ± 1.0, -0.7 ± 1.0 respectively) than controls (-0.15 ± 1.2, -0.31 ± 1.1), (p <  0.05) and trabecular density was lower at distal radius with increasing disease duration. Hand-grip strength Z-score was lower in children with T1DM (-3.0 ± 0.5) as compared to controls (-2.8 ± 0.5). Trabecular density and HbA1C concentrations were negatively correlated (R = -0.18, p < 0.05) as was muscle area and HbA1C concentrations (R = -0.17, p < 0.05,).

CONCLUSION

Bone and muscle health were affected in children with poorly controlled T1DM. With increasing disease duration, attention is required for optimising musculoskeletal health.

Vitamin D-binding protein and vitamin D receptor genotypes and 25-hydroxyvitamin D levels are associated with development of aortic and mitral valve calcification and coronary artery diseases

To assess the association between vitamin D-Binding Protein (VDBP rs7041T>G) and vitamin D receptor (VDR rs1544410G>A) gene polymorphisms with susceptibility to cardiovascular diseases in population from west of Iran. Two hundred forty-nine individuals with cardiovascular disease (92 with aortic and Mitral Valves Calcification (AMVC) and 157 with Coronary Artery Diseases (CAD) that their diseases were confirmed by echocardiography and angiography and unrelated 182 healthy controls (gender and age-matched) were selected for this case-control study. The VDR 1544410G>A, and VDBP 7041T>G genotyping were detected by PCR-RFLP, serum vitamin D and lipid concentrations were measured by ELISA and enzyme assay, respectively. The VDR rs1544410G>A gene is a strong risk factor for CAD (OR = 1.28, p = 0.002) and the dominant genotype (T/G+G/G) of VDBP 7041 T>G SNP plays a protective role (OR = 0.67, p = 0.003) in AMVC development in studied population. In addition, lower level of vitamin D strongly increased the risk of CAD (15 ± 11.02 vs. 21.3 ± 18 μg/L, p = 0.043) and AMVC (12.1 ± 13.1 vs.21.3 ± 18 μg/L, p = 0.014) development in individuals carrying T/T genotype of VDBP 7041 T>G gene polymorphism. There was a strong interaction between A allele VDR rs1544410 and G allele of VDBP rs7041 genes in a protective role (OR = 0.74, p = 0.044) in AMVC patients). CAD and AMVC patients were deficient in vitamin D, i.e. their level of vitamin D was strongly lower than that in the control group. Our findings for the first time indicated that there is a strong association between vitamin D deficiency, lipid profile and the VDR rs1544410G>A and rs7T41>G VDBP genes polymorphisms. These interactions may be one of the important factors for CAD and AMVC incidence.

Association between serum 25-hydroxyvitamin D and diabetic kidney disease in Chinese patients with type 2 diabetes

Objective

The objective was to assess the association between 25-hydroxyvitamin D (25OHD) level and diabetic kidney disease (DKD) in Chinese patients with type 2 diabetes.

Methods

Data pertaining to 351 in-patients with type 2 diabetes were collected. Subjects were classified into three groups based on the level of urinary albumin-to-creatinine ratio (UACR). UACR < 30 mg/g was defined as normoalbuminuria, while UACR levels of 30–300 mg/g and ≥ 300 mg/g were defined as microalbuminuria and macroalbuminuria, respectively. Serum 25OHD and other clinical characteristics among various UACR groups were compared. The relationship between albuminuiria and 25OHD was analyzed.

Results

The prevalence of 25OHD insufficiency in the microalbuminuria group was significantly higher than that in the normoalbuminuria group (25.1% vs. 19.6%; P < 0.05); patients with macroalbuminuria had the highest prevalence of 25OHD deficiency (37.8%; P < 0.01 versus normoalbuminuria). Logistic regression analyses demonstrated that low 25OHD levels were associated with DKD [odds ratio (OR) = 1.51, 95% confidence interval (CI) 1.16–1.97). The association was more robust after adjusting for sex, hypertension, increased systolic blood pressure, glycemic status, and hyperuricemia (OR = 1.62, 95% CI 1.19–2.20).

Conclusions

The prevalence of vitamin D insufficiency/deficiency in patients with albuminuria was overtly higher than that in patients without albuminuria among Chinese adults with type 2 diabetes. Vitamin D insufficiency/deficiency was independently associated with DKD in type 2 diabetes.

The Role of Vitamin D Binding Protein, Total and Free 25-Hydroxyvitamin D in Diabetes

Vitamin D is important for bone health, but may also have extra-skeletal effects. Vitamin D and its binding protein DBP have immunological effects and may therefore be important in the development of type 1 diabetes (T1DM), and low serum levels of 25-hydroxyvitamin D (25(OH)D) are associated with later development of type 2 diabetes (T2DM). However, it has so far been difficult to convincingly show an effect of vitamin D supplementation on prevention or treatment of diabetes. The serum level of 25(OH)D has traditionally been used as a marker of a subject's vitamin D status. This measurement includes both 25(OH)D bound to DBP and albumin as well as the free from of 25(OH)D. However, according to the free hormone hypothesis, the free form is the biologically active. Previously the free form of 25(OH)D had to be calculated based on measurements of 25(OH)D, DBP, and albumin, but recently a method for direct measurement of free 25(OH)D has become commercially available. This is important in clinical conditions where the amount of DBP is affected, and has caused a renewed interest in which vitamin D metabolite to measure in clinical situations. In the present review the relations between DBP, total and free 25(OH)D in T1DM and T2DM are described.

Immunomodulatory Effect of Vitamin D and Its Potential Role in the Prevention and Treatment of Type 1 Diabetes Mellitus-A Narrative Review

Type 1 diabetes mellitus is a chronic autoimmune disease associated with degeneration of pancreatic β-cells that results in an inability to produce insulin and the need for exogenous insulin administration. It is a significant global health problem as the incidence of this disorder is increasing worldwide. The causes are still poorly understood, although it certainly has genetic and environmental origins. Vitamin D formed profusely in the skin upon exposure to sunlight, as well as from dietary sources, exhibits an immunomodulatory effect based on gene transcription control. Indeed, vitamin D can downregulate mechanisms connected with adaptive immunity, induce immunological tolerance and decrease auto-aggression-related inflammation. These properties provide the basis for a preventive and therapeutic role of vitamin D. As many studies have demonstrated, appropriate supplementation with vitamin D reduces the risk of autoimmune diseases, including type 1 diabetes mellitus, and alleviates disease symptoms in patients. The aim of this narrative review is to present the molecular mechanisms for the vitamin D immunomodulatory effect as well as review human clinical studies on the use of vitamin D as adjuvant therapy in type 1 diabetes mellitus.

The application of post-translational modification oriented serum proteomics to assess experimental diabetes with complications

Proteome analysis of serum from type 2 diabetics with complications may lead to the discovery of diagnostic or prognostic biomarkers. To circumvent the principal barrier of serum proteomics, our investigation aimed to evaluate whether a study of post-translational modification enriched serum proteins could be valuable for the discovery of biomarkers or metabolic pathways related to type 2 diabetes pathogenesis. Type 2 diabetes was induced from high-fat diet fed Sprague Dawley rats with streptozotocin injection. Once diabetic status was confirmed, serum samples from either fasted healthy or diabetic rats were pooled and profiled by two-dimensional difference gel electrophoresis or comparative 2D electrophoresis after protein enrichments using immobilized metal ion, concanavalin A, and lentil affinity chromatography, respectively. Differential expressed proteins were identified and the associated networks were established by an Ingenuity Pathway Analysis. As a result, induced rats became severe diabetic and accompanied by hyperlipidemia, fatty liver, and glomerular hypertrophy. There were 3 total, 14 phosphorylated and 23 glycosylated protein targets differentially expressed. Proteins could be linked to HNF4A, HNF1A, and NF_κB transcriptional factors and antigen presentation, humoral immune response, and inflammatory response pathways. Predicted organ toxicity in kidney, heart, and liver matched with our histopathological results. In conclusion, post-translational modification based serum protein enrichment could be a valuable approach to enhance the resolution of serum proteomics without depleting potentially valuable abundant proteins. Our results also indicated the potential association of the hepatic secretome and hepatocyte nuclear factors in the pathogenesis of type 2 diabetes and its complications.

Vitamin D Deficiency in Chronic Kidney Disease: Recent Evidence and Controversies

Vitamin D (VD) is a pro-hormone essential for life in higher animals. It is present in few types of foods and is produced endogenously in the skin by a photochemical reaction. The final step of VD activation occurs in the kidneys involving a second hydroxylation reaction to generate the biologically active metabolite 1,25(OH)₂-VD. Extrarenal 1α-hydroxylation has also been described to have an important role in autocrine and paracrine signaling. Vitamin D deficiency (VDD) has been in the spotlight as a major public healthcare issue with an estimated prevalence of more than a billion people worldwide. Among individuals with chronic kidney disease (CKD), VDD prevalence has been reported to be as high as 80%. Classically, VD plays a pivotal role in calcium and phosphorus homeostasis. Nevertheless, there is a growing body of evidence supporting the importance of VD in many vital non-skeletal biological processes such as endothelial function, renin-angiotensin-aldosterone system modulation, redox balance and innate and adaptive immunity. In individuals with CKD, VDD has been associated with albuminuria, faster progression of kidney disease and increased all-cause mortality. Recent guidelines support VD supplementation in CKD based on extrapolation from cohorts conducted in the general population. In this review, we discuss new insights on the multifactorial pathophysiology of VDD in CKD as well as how it may negatively modulate different organs and systems. We also critically review the latest evidence and controversies of VD monitoring and supplementation in CKD patients.

Urinary vitamin D-binding protein, a novel biomarker for lupus nephritis, predicts the development of proteinuric flare

Lupus nephritis (LN) is a major complication of systemic lupus erythematosus (SLE). Conventional biomarkers for assessing renal disease activity are imperfect in predicting clinical outcomes associated with LN. The aim of this study is to identify urinary protein biomarkers that reliably reflect the disease activity or predict clinical outcomes. A quantitative proteomic analysis was performed to identify protein biomarker candidates that can differentiate between SLE patients with and without LN. Selected biomarker candidates were further verified by enzyme-linked immunosorbent assay using urine samples from a larger cohort of SLE patients ( n = 121) to investigate their predictive values for LN activity measure. Furthermore, the association between urinary levels of a selected panel of potential biomarkers and prognosis of LN was assessed with a four-year follow-up study of renal outcomes. Urinary vitamin D-binding protein (VDBP), transthyretin (TTR), retinol binding protein 4 (RBP4), and prostaglandin D synthase (PTGDS) were significantly elevated in SLE patients with LN, especially in patients with active LN ( n = 21). Among them, VDBP well correlated with severity of proteinuria (rho = 0.661, p < 0.001) and renal SLE Disease Activity Index (renal SLEDAI) (rho = 0.520, p < 0.001). In the four-year follow-up, VDBP was a significant risk factor (hazard ratio 9.627, 95% confidence interval 1.698 to 54.571, p = 0.011) for the development of proteinuric flare in SLE patients without proteinuria ( n = 100) after adjustments for multiple confounders. Urinary VDBP correlated with proteinuria and renal SLEDAI, and predicted the development of proteinuria.

Identification of HLA-A2-restricted immunogenic peptides derived from Vitamin D-Binding Protein

T-cell-mediated destruction of pancreatic β cells leads to Type 1 diabetes (TID). Vitamin D-Binding Protein (VDBP) has been identified as an autoantigen and T cell reactivity against VDBP increases in the development of T1D. Autoreactive cytotoxic T lymphocytes (CTLs) recognize β-cell-derived peptides in the context of major histocompatibility complex class I molecules. However, little is known about the VDBP-derived immunogenic peptides that are presented in the context of human HLA molecules. Here, we predicted and identified VDBP derived immunogenic peptides that were presented in association with human HLA-A2 molecule. The VDBP derived peptides binding to HLA-A∗0201 were predicted by using a computer-assisted algorithm. The candidate peptides were synthesized, then affinity between peptides and HLA-A∗0201 were analyzed. In addition, the CTL activity of the peptides was detected by cytotoxicity assay and ELISPOT assay in vitro. Furthermore, HLA-A∗0201-transgenic mice were immunized with peptides to induce the CTL activity in vivo. The results demonstrated that peptides of VDBP containing residues 211-219 and 235-243 had high affinity with HLA-A∗0201. In addition, these peptides elicited potent CTL responses in vitro, and induced T1D in vivo. Therefore, this experiment identified immunogenic HLA-A∗0201-restricted epitopes derived from VDBP, and provided pathogenesis theory of T1D.

Low levels of 25-hydroxyvitamin D in children and adolescents with type 1 diabetes mellitus: a single center experience

PURPOSE

Low vitamin D level is common in adults with diabetes mellitus (DM). We assessed vitamin D level and its associated factors in Korean youth with type 1 DM.

METHODS

Type 1 DM cases (n=85) and healthy controls (n=518) aged <20 years were included and grouped into 3 categories according to vitamin D level: deficiency (<20 ng/mL), insufficiency (20-30 ng/mL), or sufficiency (≥30 ng/mL).

RESULTS

The mean serum vitamin D level was significantly lower (21.6±8.5 ng/mL vs. 28.0±12.0 ng/mL, P<0.001) and vitamin D deficiency prevalence was significantly higher (48% vs. 26%, P<0.001) in type 1 DM cases than in healthy controls. Logistic regression analysis revealed that type 1 DM cases were more likely to have vitamin D deficiency (P=0.004), independent of sex, age, and body mass index. Type 1 DM cases with vitamin D deficiency/insufficiency were mainly diagnosed in winter (November to April) (P=0.005), and the duration of diabetes was longer than in those with vitamin D sufficiency (P=0.046). However, season of diagnosis, duration of diabetes, prescribed daily insulin dose, and glycosylated hemoglobin and C-peptide levels were not associated with 25-hydroxyvitamin D (25(OH)D) level in type 1 DM cases after adjustment for other factors.

CONCLUSIONS

We recommend assessment of serum 25(OH)D level in type 1 DM cases and to treatment if findings indicate insufficiency. Further studies investigating the mechanisms underlying vitamin D deficiency in youth with type 1 DM are needed.

Vitamin D-Binding Protein Clearance Ratio Is Significantly Associated with Glycemic Status and Diabetes Complications in a Predominantly Vitamin D-Deficient Population

INTRODUCTION

Studies have shown increased urine excretion of vitamin D-binding protein (VDBP) in patients with diabetic nephropathy (DN) resulting from postulated mechanisms linked to renal tubular damage. In this study, we evaluate the utility of VDBP clearance ratio as a novel determinant of glycemic status, DN, and other diabetes-associated complications.

METHODS

Levels of vitamin D, HbA1c, serum, urine concentrations of VDBP, and creatinine were measured in 309 subjects. The ratio of urine microalbumin to creatinine was determined to categorize subjects as normoalbuminuric (NAO), microalbuminuric (MIA), and macroalbuminuric (MAA). The VDBP clearance ratio was calculated.

RESULTS

Mean VDBP clearance ratios in NAO, MIA, and MAA were 0.7, 4, and 15, respectively. Significant positive correlations of VDBP clearance ratio were found with age, WC, SBP, DBP, TG, glucose, HbA1c, urine VDBP, urine microalbumin, and urine microalbumin/creatinine, and a significant negative correlation was found with the steady-state estimate of beta cell function (B%). Receiver operating curve (ROC) analyses of the use of VDBP clearance ratio for detection of albumin status shows a value of 0.81 for the area under the curve.

CONCLUSIONS

The strong associations of VDBP clearance ratio with glycemic control and diabetes-associated complications suggest that this index could play a wider role in detection and/or pathogenesis and complications of diabetes.

Assessment of Vitamin D-Binding Protein and Early Prediction of Nephropathy in Type 2 Saudi Diabetic Patients

Early detection of diabetic nephropathy (DN) represents a great challenge in an attempt to reduce the burden of chronic kidney diseases in diabetic patients. This study aimed to investigate the potential early prediction role of urinary vitamin D-binding protein (uVDBP) for the diagnosis of DN and to examine the possible correlation to serum VDBP, high-sensitivity C-reactive protein (hs-CRP), and insulin resistance in these patients. Serum and urine samples were obtained from 40 healthy volunteers and 120 patients with type 2 diabetes divided into 3 groups: normoalbuminuria, microalbuminuria, and macroalbuminuria (urinary albumin excretion rate < 30, 30-300, and >300 μg/mg, resp.); n = 40/group. Serum and urinary VDBP levels were quantified by ELISA. Insulin resistance has been assessed by homeostasis model assessment index (HOMAI). Correction for urine creatinine concentration was applied for urinary quantitative measurements. uVDBP levels were significantly elevated in micro- and macroalbuminuria patient groups compared with those of the normoalbuminuria patient group and controls (820.4 ± 402.8 and 1458.1 ± 210.0 compared with 193.1 ± 141.0 and 127.7 ± 21.9 ng/mg, resp.) (P < 0.001). There was significant correlation between serum and urinary levels of VDBP in total patient group. Receiver operating characteristic analysis of uVDBP levels showed optimum cut-off value of 216.0 ng/mg corresponding to 98.8% sensitivity and 80.0% specificity and an area under the curve of 0.973 to discriminate the normoalbuminuria from the microalbuminuria groups. In multivariate analysis, ordination plot showed obvious demarcation between the study groups caused by the higher levels of uVDBP and albumin/creatinine ratio among other variables. The study findings suggested a possible clinical application of uVDPB as an early and a good marker for the detection of early renal disease in type 2 DM Saudi patients. Large-scale validation studies are warranted to confirm the results before including uVDBP with the available list of other conventional biomarkers.

Profile of chronic kidney disease related-mineral bone disorders in newly diagnosed advanced predialysis diabetic kidney disease patients: A hospital based cross-sectional study

AIM

Chronic kidney disease related-mineral bone disorder (CKD-MBD) has been poorly studied in pre-dialysis Indian CKD population. There are limited data on the pattern of these disturbances in diabetic CKD patients. Therefore, a study was conducted to find out the profile of mineral bone disorders in T2DM patients with pre-dialysis CKD.

METHODS

In this cross-sectional design, diabetic patients with newly-diagnosed stage 4 and 5 CKD were evaluated. Serum levels of calcium, phosphorus, intact parathyroid hormone (iPTH), 25 hydroxy vitamin D and total alkaline phosphatase (ALP) were measured in all patients. Bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry (DXA).

RESULTS

A total of 72 eligible patients participated (44 males, 28 females; age 54.2±11.7). Patients with CKD Stage 5 had a lower level of corrected serum calcium and significantly higher level of inorganic phosphorus, total ALP and iPTH as compared to stage 4 patients. Overall, 38.5% were hypocalcemic, 31.43% were hyperphosphatemic. 24.2% of CKD subjects were vitamin D deficient (<10ng/ml) and 41.4% having vitamin D insufficiency (10-20ng/ml). In stage 4, hyperparathyroidism (iPTH>110pg/ml) was detected in nearly 43% of patients. In stage 5, only 32% patients was found to have hyperparathyroidism (iPTH>300pg/ml). There was a good correlation between iPTH and total ALP (r=0.5, p=0.0001) in this cohort. 25 (OH) vitamin D was inversely correlated with ALP (r=-0.39, P=0.001) and showed negative correlation with urine ACR (r=-0.37, P=0.002). As a group, the osteoporotic CKD subjects exhibited higher iPTH (220.1±153.8 vs. 119±108pg/ml, p<0.05) as compared to those who were osteopenic or had normal bone density. There was significant correlation between BMD and iPTH (adjusted r=-0.436; P=0.001). In the multivariate regression model, we found intact PTH to predict BMD even after adjustment of all the confounders.

CONCLUSION

The current study showed that adynamic bone disease is prevalent even in pre-dialysis CKD population. High bone turnover disease may not be the most prevalent type in diabetic CKD. However, it could contribute to the development of osteoporosis in CKD subjects. Serum total ALP can serve as a biochemical marker to identify pattern of bone turnover where intact PTH is not available.

A lack of association between vitamin D-binding protein and 25-hydroxyvitamin D concentrations in pediatric type 1 diabetes without microalbuminuria

PURPOSE

Vitamin D deficiency is reported to be more common in type 1 diabetes patients and might be associated with the increased urinary loss of vitamin D binding protein (VDBP) consequent to impaired 25-hydroxyvitamin D (25(OH)D) circulation. We aimed to evaluate the possible increased urinary loss of VDBP, a correlation between VDBP and circulating 25(OH)D level, and risk factors influencing low vitamin D level in pediatric type 1 diabetes patients without microalbuminuria.

METHODS

This is a cross-sectional study of subjects who visited Seoul National University Children's Hospital between January and March 2013. Forty-two type 1 diabetes patients and 29 healthy controls were included. Biochemical parameters including serum and urine VDBP concentrations were analyzed.

RESULTS

There was no significant difference in the frequency of vitamin D deficiency or serum 25(OH)D level between the 2 groups. The serum and urine VDBP concentrations did not show any difference between the 2 groups. Serum 25(OH) D level did not correlate with serum or urine VDBP. Multivariate regression analysis revealed that daylight outdoor hours (β=2.948, P=0.003) and vitamin D intake (β=2.865, P=0.003) affected the 25(OH)D level; the presence of type 1 diabetes or urinary VDBP excretion was not significant.

CONCLUSIONS

In pediatric type 1 diabetes patients, urinary VDBP excretion did not contribute to low serum 25(OH)D level in the setting of normoalbuminuria. The factors associated with 25(OH)D level during winter periods were daylight outdoor hours and vitamin D intake. Further studies including both micro- and macroalbuminuria patients with type 1 diabetes are warranted.

The cellular selection between apoptosis and autophagy: roles of vitamin D, glucose and immune response in diabetic nephropathy

BACKGROUND AND AIMS

Apoptosis, autophagy and cell cycle arrest are cellular responses to injury which are supposed to play fundamental roles in initiation and progression of diabetic nephropathy (DN). The aims of the present study is to shed light on the potential effects of vitamin D analog 22-oxacalcitriol (OCT) on different cell responses during DN, and the possible interplay between both glucose, immune system and vitamin D in determining the cell fate.

METHOD

All rats were randomly allocated into one of three groups: control, vehicle-treated DN group and OCT-treated DN group. Eight weeks after induction of diabetes, the rats were killed. Fasting blood glucose levels, serum 25 (OH) D, renal functions, cytokines and gene expression of autophagy, apoptotic and cell cycle arrest markers were assessed. In addition, the histological assessment of renal architecture was done.

RESULTS

OCT treatment remarkably improved the renal functions and albuminuria. The reductions in mesangial cell hypertrophy, extracellular matrix as well as cell loss were significantly associated with upregulation of pro-autophagy gene expressions and downregulation of both pro-apoptotic and G1-cell cycle arrest genes expression. The reno-protective effects of OCT treatment were associated with significant attenuation of the fasting blood glucose, serum IL-6, renal TLR-4 and IFN-g gene expression.

CONCLUSION

Modulator effects of OCT on glucose and immune system play important roles in renal cell fate decision and chronic kidney disease progression.

Vitamin D status in Egyptian children with type 1 diabetes and the role of vitamin D replacement in glycemic control

BACKGROUND

The association of low serum 25 hydroxy cholecalciferol (25OHD) levels with high glucose level and diminished insulin sensitivity suggests that vitamin D (VD) may modulate insulin metabolism. The aim of the study was to screen for vitamin D deficiency (VDD) in pediatric patients with type 1 diabetes (T1D) and study the effect of VD supplementation on their glycemic control and insulin requirements.

METHODS

A prospective cohort study including 50 patients with T1D. VD level was assessed initially and after 3 months of VD supplementation (in those with VDD). HbA1c and insulin requirements were studied at 0, 3 and 6 months of supplementation.

RESULTS

Fifty patients with T1D were included with mean diabetes duration of 4.11±2.34 years. VD level ranged from 0.2 to 33 ng/mL. VD status correlated significantly with daily insulin dose (p=0.030, r=0.306) and HbA1c (p<0.001, r=0.243). Thirty-five patients (70%) had VDD and were allocated for VD supplementation for 3 months. The mean HbA1c improved significantly after supplementation (p=0.003), followed by a significant deterioration at 6 months with no change in their insulin requirements at 3 or 6 months.

CONCLUSIONS

VD was highly prevalent in Egyptian T1D patients. VD supplementation improved glycemic control at 3 months after therapy with no reduction in insulin requirements.

Molecular actions of vitamin D in reproductive cell biology

Vitamin D (VitD) is an important secosteroid and has attracted attention in several areas of research due to common VitD deficiency in the population, and its potential to regulate molecular pathways related to chronic and inflammatory diseases. VitD metabolites and the VitD receptor (VDR) influence many tissues including those of the reproductive system. VDR expression has been demonstrated in various cell types of the male reproductive tract, including spermatozoa and germ cells, and in female reproductive tissues including the ovaries, placenta and endometrium. However, the molecular role of VitD signalling and metabolism in reproductive function have not been fully established. Consequently, the aim of this work is to review current metabolic and molecular aspects of the VitD–VDR axis in reproductive medicine and to propose the direction of future research. Specifically, the influence of VitD on sperm motility, calcium handling, capacitation, acrosin reaction and lipid metabolism is examined. In addition, we will also discuss the effect of VitD on sex hormone secretion and receptor expression in primary granulosa cells, along with the impact on cytokine production in trophoblast cells. The review concludes with a discussion of the recent developments in VitD–VDR signalling specifically related to altered cellular bioenergetics, which is an emerging concept in the field of reproductive medicine.

Vitamin D on Early Stages of Diabetic Kidney Disease: A Cross-sectional Study in Patients with Type 1 Diabetes Mellitus

CONTEXT

Genetic and environmental factors are involved in the pathogenesis of type 1 diabetes mellitus (T1DM), and vitamin D (VD) deficiency appears as a candidate to risk factor for developing diabetic kidney disease (DKD).

OBJECTIVE

The purpose of study was to evaluate the existence of an association between low levels of VD and the presence and degree of DKD in T1DM.

PATIENTS AND METHODS

We performed a cross-sectional study, between November 2014 and December 2015. Levels of 25(OH)D and albuminuria were analyzed in 37 patients with T1DM and normal glomerular filtration rate. Thirty-six subjects were evaluated as a control group.

RESULTS

Patients with T1DM and hypovitaminosis D had higher levels of albuminuria compared to those with normal VD levels [albuminuria (log10) = 1.92 vs. 1.44; p < 0.05]. When we have separated the group of patients according to stage of DKD in patients with normo, micro, and macroalbuminuria, there are lower levels of 25(OH)D in the last when compared to the first two groups (26.7 ± 6.2, 24.8 ± 7.0, and 15.9 ± 7.6 ng/ml; p < 0.05, respectively). In T1DM group, we have found correlations between VD levels and both albuminuria and DKD stages (r = -0.5; p < 0.01 and r = -0.4; p < 0.05, respectively). A simple linear regression model, with albuminuria as the dependent variable and VD as an independent variable, showed r2 = 0.2 and p < 0.01.

CONCLUSION

Our data suggest an association between reduced levels of VD and the presence and severity of DKD.

Epidemiology of Skeletal Health in Type 1 Diabetes

The skeleton is adversely affected by type 1 diabetes (T1D). Patients with T1D of both sexes have an increased risk of fracture that begins in childhood and extends across the entire lifespan. T1D is characterized by mild to modest deficits in bone density, structure, and microarchitecture. Current evidence suggests that the observed bone deficits in T1D are the result of impaired bone formation rather than increased bone resorption. There is emerging data that bone quality is impaired in T1D, which may explain the findings that fracture risk is elevated out of proportion to the degree of bone mineral deficit. In this review, we summarize the current knowledge regarding the epidemiology of skeletal health in T1D. Given the high individual and societal burden of osteoporotic fracture, there is an urgent need to better understand the etiology of T1D-related bone disease so that clinical strategies to prevent fracture can be developed.

Vitamin D status in youth with type 1 and type 2 diabetes enrolled in the Pediatric Diabetes Consortium (PDC) is not worse than in youth without diabetes

OBJECTIVE

To describe vitamin D levels and prevalence of vitamin D sufficiency, insufficiency and deficiency in a large, ethnically/racially diverse population of youth with type 1 diabetes (T1D) and type 2 diabetes (T2D) in comparison to national data and examine the associations between clinical/demographic factors and vitamin D levels.

METHODS

25-hydroxy vitamin D (25OHD) levels were measured in 215 youth with T1D and 326 youth with T2D enrolled in the Pediatric Diabetes Consortium (PDC). These levels were compared with those of youth of the same age without diabetes from the 2005-2006 NHANES Survey.

RESULTS

Vitamin D deficiency (<21 ng/mL) was present in 36% of PDC participants, and insufficiency (21-29 ng/mL) was present in an additional 34%. About 36% of age-matched youth in the NHANES Survey were vitamin D deficient and an additional 41% were insufficient. Deficiency or insufficiency varied by race/ethnicity, being highest in African-Americans (86%), intermediate in Hispanics (77%), and lowest in non-Hispanic whites (47%). Lower 25OHD levels were observed in African-American and Hispanic youth, during fall and winter, and at sites in the northern United States (all p-values < 0.001). Youth with T2D had significantly lower 25OHD levels than youth with T1D (p < 0.001), but this difference was largely eliminated after adjusting for race/ethnicity and socio-economic status.

CONCLUSIONS

Vitamin D deficiency/insufficiency is present in a substantial proportion of youth with diabetes, particularly minorities, but the prevalence appears similar to that in youth without diabetes. Further studies are needed to examine whether youth with diabetes would benefit from vitamin D supplementation.

Critically Ill Children Have Low Vitamin D-Binding Protein, Influencing Bioavailability of Vitamin D

RATIONALE

Vitamin D deficiency, often defined by total serum 25-hydroxyvitamin D (25[OH]D) <20 ng/ml, is common in critically ill patients, with associations with increased mortality and morbidity in the intensive care unit. Correction of vitamin D deficiency in critical illness has been recommended, and ongoing clinical trials are investigating the effect of repletion on patient outcome. The biologically active amount of 25(OH)D depends on the concentration and protein isoform of vitamin D-binding protein (VDBP), which is also an acute-phase reactant affected by inflammation and injury.

OBJECTIVES

We performed a secondary analysis of a cohort of critically ill children in which we reported a high rate of vitamin D deficiency, to examine how VDBP level and genotype would impact vitamin D status.

METHODS

We prospectively enrolled 511 children admitted to the pediatric intensive care unit over a 12-month period.

MEASUREMENTS AND MAIN RESULTS

We measured serum VDBP in 479 children. We genotyped single nucleotide polymorphisms rs7041 and rs4588 in the VDBP gene (GC) to determine haplotypes GC1F, GC1S, and GC2 in 178 subjects who consented, then calculated bioavailable 25(OH)D from serum 25(OH)D, VDBP, albumin, and GC haplotype. The median serum VDBP level was 159 μg/ml (interquartile range, 108-221), lower than has been reported in healthy children. Factors predicting lower levels in multivariate analysis included age <1 year, nonwhite race, being previously healthy, 25(OH)D <20 ng/ml and greater illness severity. In the subgroup that was genotyped, GC haplotype had the strongest association with VDBP level; carriage of one additional copy of GC1S was associated with a 37.5% higher level (95% confidence interval, 31.9-44.8; P < 0.001). Bioavailable 25(OH)D was also inversely associated with illness severity (r = -0.24, P < 0.001), and ratio to measured total 25(OH)D was variable and related to haplotype.

CONCLUSIONS

Physiologic deficiency of 25(OH)D in critical illness may be more difficult to diagnose, given that lower VDBP levels increase bioavailability. Treatment studies conducted on the basis of total 25(OH)D level, without consideration of VDBP concentration and genotype, may increase the risk of falsely negative results.

Impact of Long-Term Poor and Good Glycemic Control on Metabolomics Alterations in Type 1 Diabetic People

CONTEXT

Poor glycemic control in individuals with type 1 diabetes (T1D) is associated with both micro- and macrovascular complications, but good glycemic control does not fully prevent the risk of these complications.

OBJECTIVE

The objective of the study was to determine whether T1D with good glycemic control have persistent abnormalities of metabolites and pathways that exist in T1D with poor glycemic control.

DESIGN

We compared plasma metabolites in T1D with poor (glycated hemoglobin ≥ 8.5%, T1D[-] and good (glycated hemoglobin < 6.5%, T1D[+]) glycemic control with nondiabetic controls (ND).

SETTING

The study was conducted at the clinical research unit.

PATIENTS OR OTHER PARTICIPANTS

T1D with poor (n = 14), T1D(-) and good, T1D(+) (n = 15) glycemic control and matched (for age, sex, and body mass index) ND participants were included in the study.

INTERVENTION(S)

There were no intervention.

MAIN OUTCOME MEASURE(S)

Comparison of qualitative and quantitative profiling of metabolome was performed.

RESULTS

In T1D(-), 347 known metabolites belonging to 38 metabolic pathways involved in cholesterol, vitamin D, tRNA, amino acids (AAs), bile acids, urea, tricarboxylic acid cycle, immune response, and eicosanoids were different from ND. In T1D(+),154 known metabolites belonging to 26 pathways including glycolysis, gluconeogenesis, bile acids, tRNA biosynthesis, AAs, branch-chain AAs, retinol, and vitamin D metabolism remained altered from ND. Targeted measurements of AA metabolites, trichloroacetic acid, and free fatty acids showed directional changes similar to the untargeted metabolomics approach.

CONCLUSIONS

Comprehensive metabolomic profiling identified extensive metabolomic abnormalities in T1D with poor glycemic control. Chronic good glycemic control failed to normalize many of these perturbations, suggesting a potential role for these persistent abnormalities in many complications in T1D.

Serum 25-Hydroxyvitamin D Concentrations in Children Progressing to Autoimmunity and Clinical Type 1 Diabetes

CONTEXT

The role of vitamin D in the development of type 1 diabetes (T1D) remains controversial.

OBJECTIVE

The objective of the investigation was to study whether there are detectable differences in serum 25-hydroxyvitamin D (25[OH]D) concentrations between children who later progressed to T1D (cases) and matched children who remained nondiabetic and negative for islet autoantibodies (controls) when followed up from birth until disease onset.

DESIGN

A total of 3702 prospective serum samples from 252 children were measured for 25(OH)D from the age of 3 months onward using an enzyme immunoassay. Differences between the groups were compared by the mixed-model analysis of variance.

SETTING

T1D prediction and prevention study clinics in Turku, Oulu, and Tampere University Hospitals, Finland, participated in the study.

PARTICIPANTS

By the end of 2012, all 126 case children were diagnosed with T1D. The control children (n = 126) were matched for age, sex, study site, and human leukocyte antigen-HLA-DQ-conferred risk for T1D.

MAIN OUTCOME MEASURE

Median circulating 25(OH)D concentration (nanomoles per liter) was measured.

RESULTS

The patterns of variation in circulating 25(OH)D concentrations were similar between cases and controls and did not correlate with the age at seroconversion to autoantibody positivity (P = .79) or disease onset (P = .13). The median concentration of all collected samples did not differ between case and control children (66.6 nmol/L [range 14.0-262.8] vs 67.4 nmol/L [range 19.9-213.0]) P = .56).

CONCLUSIONS

This study shows that serum 25(OH)D concentrations are not associated with the development of T1D in Finland.

Urinary Vitamin D Binding Protein and KIM-1 Are Potent New Biomarkers of Major Adverse Renal Events in Patients Undergoing Coronary Angiography

Background

Vitamin-D-binding protein (VDBP) is a low molecular weight protein that is filtered through the glomerulus as a 25-(OH) vitamin D 3/VDBP complex. In the normal kidney VDBP is reabsorbed and catabolized by proximal tubule epithelial cells reducing the urinary excretion to trace amounts. Acute tubular injury is expected to result in urinary VDBP loss. The purpose of our study was to explore the potential role of urinary VDBP as a biomarker of an acute renal damage.

Method

We included 314 patients with diabetes mellitus or mild renal impairment undergoing coronary angiography and collected blood and urine before and 24 hours after the CM application. Patients were followed for 90 days for the composite endpoint major adverse renal events (MARE: need for dialysis, doubling of serum creatinine after 90 days, unplanned emergency rehospitalization or death).

Results

Increased urine VDBP concentration 24 hours after contrast media exposure was predictive for dialysis need (no dialysis: 113.06 ± 299.61ng/ml, n = 303; need for dialysis: 613.07 ± 700.45 ng/ml, n = 11, Mean ± SD, p<0.001), death (no death during follow-up: 121.41 ± 324.45 ng/ml, n = 306; death during follow-up: 522.01 ± 521.86 ng/ml, n = 8; Mean ± SD, p<0.003) and MARE (no MARE: 112.08 ± 302.00ng/ml, n = 298; MARE: 506.16 ± 624.61 ng/ml, n = 16, Mean ± SD, p<0.001) during the follow-up of 90 days after contrast media exposure. Correction of urine VDBP concentrations for creatinine excretion confirmed its predictive value and was consistent with increased levels of urinary Kidney Injury Molecule-1 (KIM-1) and baseline plasma creatinine in patients with above mentioned complications. The impact of urinary VDBP and KIM-1 on MARE was independent of known CIN risk factors such as anemia, preexisting renal failure, preexisting heart failure, and diabetes.

Conclusions

Urinary VDBP is a promising novel biomarker of major contrast induced nephropathy-associated events 90 days after contrast media exposure.

Bone status of Indian children and adolescents with type 1 diabetes mellitus

OBJECTIVE

Low bone mineral density has been reported in children and adolescents with type 1 diabetes (T1DM). The aims of this cross-sectional study were to study growth, serum IGF1 concentrations and bone health parameters assessed by Dual Energy X-ray Absorptiometry (DXA).

METHODS

Height was measured and converted to Z scores (HAZ). Serum IGF1 concentrations were measured (ELISA) in a subset. Bone mineral content for total body (less head) (TBBMC) and lumbar spine was measured (n=170, 77 boys, 6-16years old) and converted to Z scores using local normative data.

RESULT

Mean age was 11.1±3.8years, disease duration was 2.2±2.5years and HbA1C was 10.1±1.8%. Diabetic children were shorter than reference population (HAZ -0.6±1.1); Z scores for height and total body bone area (TBBA) for height were <-2SD in 12% & 6% respectively. Serum IGF1 Z scores were lower amongst group with longer disease duration (-1.58±1.3 vs -2.63±0.7; P=0.037). Disease duration (β=-0.180, P=0.000) and metabolic control (HbA1C; β=-0.096, P=0.042) were negative predictors of HAZ and TBBA for height Z in younger children. Using the Molgaard approach, children with longer disease duration had lower HAZ (-0.31±0.92 vs -1.28±1.11; P=0.000; "short bones") and TBBA for height Z scores (0.12±1.62 vs -0.53±0.94; P=0.044; "slender bones"). Older children (tanner stages 4 and 5) had lower BMC and BA as compared to reference population possibly due to delayed growth spurt.

CONCLUSION

Longer duration of diabetes was associated with shorter and slender but appropriately mineralized bones. Small and slender bones in diabetic children may increase risk of fragility fractures in the future. This article is part of a Special Issue entitled "Bone and diabetes".

CTX Correlation to Disease Duration and Adiponectin in Egyptian Children with T1DM

BACKGROUND

In this study, we investigated the relationship of adiponectin with bone marker changes in Egyptian children and adolescents with T1DM and the effect of disease duration on these markers, as well as the possible correlations between adiponectin and bone markers in these patients.

METHODS

Sixty Egyptian children and adolescent patients with T1DM were studied. Serum adiponectin and collagen breakdown products (cross-linked C-terminal telopeptide of collagen type l »CTX«) were measured and compared to the results of 20 age-matched healthy controls.

RESULTS

After adjustment for age, BMI, Tanner stage and gender; (total) adiponectin was significantly higher in all T1DM patients. Serum level of CTX and 25(OH)D showed a marked decrease in diabetics with disease duration > 5 years. Serum level of (total) calcium and inorganic phosphorus (Pi) did not show significant difference from control. CTX was inversely correlated to FBG and T1DM duration. Pi was inversely, while 25(OH)D was directly correlated to FBG. Total calcium showed an inverse correlation with HbA1c. FBG, TC, TAG, LDL-C were independent predictors of CTX in T1DM.

CONCLUSIONS

Adiponectin showed no correlation with either CTX or bone homeostatic indices. FBG, TC, TAG, LDL-C were independent predictors of CTX in T1DM. We recommend further investigation of adiponectin isoforms in a population-based study, to establish a good age- and sex-related reference.

Behind the scenes of vitamin D binding protein: more than vitamin D binding

Although being discovered in 1959, the number of published papers in recent years reveals that vitamin D binding protein (DBP), a member of the albuminoid superfamily, is a hot research topic. Besides the three major phenotypes (DBP1F, DBP1S and DBP2), more than 120 unique variants have been described of this polymorphic protein. The presence of DBP has been demonstrated in different body fluids (serum, urine, breast milk, ascitic fluid, cerebrospinal fluid, saliva and seminal fluid) and organs (brain, heart, lungs, kidneys, placenta, spleen, testes and uterus). Although the major function is binding, solubilization and transport of vitamin D and its metabolites, the name of this glycoprotein hides numerous other important biological functions. In this review, we will focus on the analytical aspects of the determination of DBP and discuss in detail the multifunctional capacity [actin scavenging, binding of fatty acids, chemotaxis, binding of endotoxins, influence on T cell response and influence of vitamin D binding protein-macrophage activating factor (DBP-MAF) on bone metabolism and cancer] of this abundant plasma protein.

Vitamin D-Binding Protein in Health and Chronic Kidney Disease

Vitamin D-binding protein (DBP) is a multifunctional protein that has attracted increasing interest in recent years, largely because of its potential role in modulating the activity of vitamin D. Nearly all circulating vitamin D (~85-90%) circulates bound to DBP, with a smaller proportion bound to albumin, leaving <5% circulating freely. DBP may also play roles beyond vitamin D binding, with potential roles in the immune system and elsewhere. Numerous polymorphisms of DBP exist around the world, and recent studies have identified relevance of different DBP phenotypes in determining DBP concentration and vitamin D affinity. This review focuses on the known roles of DBP in health and kidney disease, and current views on the relevance of DBP polymorphisms.