Circulating vitamin D binding protein, total, free and bioavailable 25-hydroxyvitamin D and risk of colorectal cancer

The potential role of vitamin D binding protein in kidney disease: a comprehensive review

Chronic kidney disease (CKD) is a growing health concern with a complex etiological landscape. Among the numerous factors implicated, vitamin D binding protein (VDBP) has emerged as a focal point of scientific studies because of its critical role in vitamin D metabolism and immune modulation. The relationship between VDBP and CKD reveals a complex web of molecular and biochemical details that have great potential for improving diagnostic understanding and treatment strategies for CKD. This review summarizes the multifaceted roles of VDBP, including its molecular dynamics, interactions with vitamin D, and subsequent implications for kidney function. The main focus of the discussion is how VDBP affects bone mineral homeostasis, highlighted by the dysregulation of calcium and phosphorus metabolism, which is a part of the pathophysiology of CKD. The discussion also touches on the immunomodulatory scope of VDBP and how it may reduce the chronic inflammatory environment that accompanies CKD. The diagnostic potential of VDBP as a biomarker for CKD has been rigorously examined, highlighting its capacity to improve early detection and prognostic assessment. Modification of VDBP activity has the potential to slow the course of CKD and improve patient outcomes. Furthermore, a detailed examination of the genetic polymorphisms of VDBP and their implications for CKD susceptibility and treatment responsiveness provides a perspective for personalized medical methods. Prospects for the future depend on the expansion of studies that try to understand the molecular mechanisms underlying the VDBP-CKD interaction, in addition to clinical trials that evaluate the effectiveness of VDBP-focused treatment approaches.

Circulating vitamin D levels and colorectal cancer risk: A meta-analysis and systematic review of case-control and prospective cohort studies

The associations between circulating vitamin D concentrations and total and site-specific colorectal cancer (CRC) incidence have been examined in several epidemiological studies with overall inconclusive findings. The aim of this systematic review and meta-analysis of both case-control and prospective cohort studies was to evaluate the association between CRC and circulating levels of vitamin D. The main exposure and outcome were circulating total 25(OH)D and CRC, respectively, in the overall population (i.e., all subjects). Two reviewers, working independently, screened all the literature available to identify studies that met the inclusion criteria (e.g., case-control or prospective cohort studies, published in English, and excluding non-original papers). Data were pooled by the generic inverse variance method using a random or fixed effect model, as approriate. Heterogeneity was identified using the Cochran's Q-test and quantified by the I² statistic. Results were stratified by study design, sex, and metabolite of vitamin D. Sensitivity and subgroup analyses were also performed. A total of 28 original studies were included for the quantitative meta-analysis. Meta-analyses comparing the highest vs lowest categories, showed a 39% lower risk between levels of total 25(OH)D and CRC risk (OR (95% CI): 0.61 (0.52; 0.71); 11 studies) in case-control studies; whereas a 20% reduced CRC risk in prospective cohort studies (HR (95% CI): 0.80 (0.66; 0.97); 6 studies). Results in women mirrored main results, whereas results in men were non-significant in both analyses. Our findings support an inverse association between circulating vitamin D levels and CRC risk.

Is there a link between vitamin D status, SARS-CoV-2 infection risk and COVID-19 severity?

The outbreak of COVID-19 emerged in December 2019 rapidly spread across the globe and has become pandemic. Little is known about the protective factors of this infection, which is equally distributed between genders and different ages while severe and poor prognosis cases are strongly associated to old males and the presence of comorbidities. Thus, preventive measures aiming at reducing the number of infection and/or their severity are strongly needed. Vitamin D has got great attention and has been claimed as potentially protective against the infection since it may be associated with immunocompetence, inflammation, aging, and those diseases involved in determining the outcomes of COVID-19. This narrative review aims at collecting the literature available on the involvement of the vitamin D status in the pathogenesis of COVID-19 and the putative utility of vitamin D supplementation in the therapeutics. It emerges that a poor vitamin D status seems to associate with an increased risk of infection whereas age, gender and comorbidities seem to play a more important role in COVID-19 severity and mortality. While randomized control trials are needed to better inquire into this topic, vitamin D supplementation may be useful beside its potential effects on SARS-CoV-2 infection and COVID-19.

[Power station sun and hormone factory skin : A current assessment of the importance of vitamin D metabolism during human evolution and strategies for UV prevention]

The sun is of great importance for human health. One important reason for this is the production of vitamin D, endorphins and many other hormones by the skin due to stimulation by sunlight. Insufficient access to sunlight increases the risk for vitamin D deficiency, a pandemic which would affect more than one billion people worldwide and under which ca. 60% of the population in Germany would suffer. The skin has a unique position in vitamin D metabolism as elementary steps for vitamin D production take place here and it is furthermore a target organ for actions of vitamin D. Due to the many positive effects of the sun, a healthy balance must be found between UV protection to shield against skin cancer but also ensuring sufficient vitamin D production. For regulation of this fragile balance between photoprotection and vitamin D production, which has accompanied mankind throughout evolution, sunscreens are an integral part of the modern lifestyle, although critical reports on possible risks for their use have recently become more frequent. This article discusses the current state of knowledge on the importance of vitamin D metabolism in human skin and the use of sun creams.

Early Pregnancy Vitamin D Binding Protein Is Independently Associated with the Development of Gestational Diabetes: A Retrospective Cohort Study

BACKGROUND

Vitamin D-binding protein (VDBP) has been implicated in several adverse pregnancy outcomes either directly or indirectly via influencing the concentrations of biologically active vitamin D metabolites. However, human studies exploring these metabolites in pregnancy remain sparse. Here, we examine whether VDBP and total, free, and bioavailable 25-hydroxyvitamin D (25(OH)D) metabolites in early pregnancy are associated with subsequent adverse pregnancy outcomes.

METHODS

We conducted a retrospective analysis of 304 pregnant women in early pregnancy (<20 weeks gestation). The demographic characteristics, anthropometric data, and total 25(OH)D were measured and plasma or serum samples were collected and bio-banked. Using these samples, we measured VDBP (polyclonal ELISA) and albumin (automated colorimetry), and calculated free and bioavailable 25(OH)D using validated formulae. Pregnancy outcomes were derived from scanned medical records. Regression models were used to analyse the relationships between vitamin D metabolites in early pregnancy and subsequent pregnancy outcomes (gestational diabetes mellitus (GDM), pre-eclampsia, preterm birth), with adjustment for predetermined clinically relevant maternal factors including age, body mass index (BMI), and ethnicity.

RESULTS

Lower VDBP concentrations were associated with higher glucose levels and a greater likelihood of developing GDM at 26-28 weeks gestation (odds ratio [OR] (95% CI) = 0.98 (0.97,0.99), p = 0.015). This finding remained significant after adjustment for maternal covariates including age, BMI, and ethnicity (β = -0.003, p = 0.03). Lower total, free and bioavailable 25(OH)D, but not VDBP, were associated with a shorter length of gestation, but only the relationship with total 25(OH)D remained significant after adjustment for the above maternal covariates (β = 0.02, p = 0.006).

CONCLUSIONS

This is the first study to examine VDBP, and total, free and bioavailable 25(OH)D in relation to pregnancy outcomes in a well characterised multi-ethnic cohort of pregnant women. Our findings show that VDBP and total 25(OH)D are associated with GDM and length of gestation, respectively; however, further investigations using large-scale prospective studies are needed to confirm our findings.

Super Secondary Structures of Proteins with Post-Translational Modifications in Colon Cancer

New advances in protein post-translational modifications (PTMs) have revealed a complex layer of regulatory mechanisms through which PTMs control cell signaling and metabolic pathways, contributing to the diverse metabolic phenotypes found in cancer. Using conformational templates and the three-dimensional (3D) environment investigation of proteins in patients with colorectal cancer, it was demonstrated that most PTMs (phosphorylation, acetylation, and ubiquitination) are localized in the supersecondary structures (helical pairs). We showed that such helical pairs are represented on the outer surface of protein molecules and characterized by a largely accessible area for the surrounding solvent. Most promising and meaningful modifications were observed on the surface of vitamin D-binding protein (VDBP), complement C4-A (CO4A), X-ray repair cross-complementing protein 6 (XRCC6), Plasma protease C1 inhibitor (IC1), and albumin (ALBU), which are related to colorectal cancer developing. Based on the presented data, we propose the impact of the observed modifications in immune response, inflammatory reaction, regulation of cell migration, and promotion of tumor growth. Here, we suggest a computational approach in which high-throughput analysis for identification and characterization of PTM signature, associated with cancer metabolic reprograming, can be improved to prognostic value and bring a new strategy to the targeted therapy.

Association of thyroid cancer risk with plasma 25-hydroxyvitamin D and vitamin D binding protein: a case-control study in China

PURPOSE

To investigate the association of thyroid cancer (TC) with 25-hydroxyvitamin D [25(OH)D] and vitamin D binding protein (DBP) and examine whether there was an interaction between 25(OH)D and DBP in relation to TC risk.

METHODS

A matched case-control study based on multiple hospitals included 506 pairs of cases with newly diagnosed TC and controls. All subjects were divided into the quartiles according to the distribution of 25(OH)D and DBP in controls. Odds ratio (OR) and 95% confidence intervals (CIs) for the association of TC with 25(OH)D and DBP were estimated by conditional logistic regression.

RESULTS

Comparing the highest to lowest quartiles, a decreased TC risk was respectively associated with plasma 25(OH)D (OR 0.63, 95% CI 0.40-1.00, P-trend = 0.046) and DBP (OR 0.49, 95% CI 0.32-0.77, P-trend = 0.001). However, the association between DBP and TC might be modified by 25(OH)D (P-interaction = 0.014) and physical activity (P-interaction = 0.017). Compared to participants with 25(OH)D and DBP concentrations respectively below medians, those with both concentrations above medians had a lower risk of TC (OR 0.56, 95% CI 0.39-0.82). In stratified analysis based on clinical characteristics of tumor, significantly negative association between 25(OH)D, and DBP and TC were observed among the cases with early stage of tumor progression.

CONCLUSIONS

This study suggested that 25(OH)D and DBP had protective effects against TC. But the negative association between TC and DBP might be modified by 25(OH)D and physical activity.

Association of Circulating Vitamin D With Colorectal Cancer Depends on Vitamin D-Binding Protein Isoforms: A Pooled, Nested, Case-Control Study

BACKGROUND

Higher circulating 25-hydroxyvitamin-D [25(OH)D] concentrations are consistently inversely associated with colorectal cancer (CRC) risk in observational studies. However, it is unknown whether this association depends on the functional GC-rs4588*A (Thr436Lys) variant encoding the vitamin D-binding protein-2 (DBP2) isoform, which may affect vitamin D status and bioavailability.

METHODS

We analyzed data from 1710 incident CRC cases and 1649 incidence-density-matched controls nested within three prospective cohorts of mostly Caucasians. Study-specific incidence rate ratios (RRs) for associations of prediagnostic, season-standardized 25(OH)D concentrations according to DBP2 isoform with CRC were estimated using multivariable unconditional logistic regression and were pooled using fixed-effects models. All statistical significance tests were two-sided.

RESULTS

The odds of having 25(OH)D concentrations less than 50 nmol/L (considered insufficient by the Institute of Medicine) were 43% higher for each DBP2-encoding variant (rs4588*A) inherited (per DBP2 odds ratio [OR] = 1.43, 95% confidence interval [CI] = 1.27 to 1.62, P trend = 1.2 × 10-8). The association of 25(OH)D concentrations with CRC risk differed by DBP2: 25(OH)D concentrations considered sufficient (≥ 50 nmol/L), relative to deficient (< 30 nmol/L), were associated with a 53% lower CRC risk among individuals with the DBP2 isoform (RR = 0.47, 95% CI = 0.33 to 0.67), but with a non-statistically significant 12% lower risk among individuals without it (RR = 0.88, 95% CI = 0.61 to 1.27) (P heterogeneity = .01).

CONCLUSIONS

Our results suggest that the 25(OH)D-CRC association may differ by DBP isoform, and those with a DBP2-encoding genotype linked to vitamin D insufficiency may particularly benefit from adequate 25(OH)D for CRC prevention.

Association between blood circulating vitamin D and colorectal cancer risk in Asian countries: a systematic review and dose-response meta-analysis

OBJECTIVES

To assess the association between blood circulating vitamin D levels and colorectal cancer risk in the Asian population.

DESIGN

This is a systematic review and dose-response meta-analysis of observational studies that investigated the relationship between blood circulating vitamin D levels and colorectal cancer risk in the Asian population.

DATA SOURCES

Relevant studies were identified through a literature search in Medline, Embase and Web of Science from 1st January 1980 to 31st January 2019. Eligibility criteria: original studies published in peer-reviewed journals investigating the association between blood circulating vitamin D levels and the risk of colorectal cancer and/or adenoma in Asian countries.

DATA EXTRACTION AND SYNTHESIS

Two authors independently extracted data and assessed the quality of included studies. Study-specific ORs were pooled using a random-effects model. A dose-response meta-analysis was performed with generalised least squares regression. We applied the Newcastle-Ottawa Scale quality assessment to evaluate the quality of the selected studies.

RESULTS

The eight included studies encompassed a total of 2916 cases and 6678 controls. The pooled ORs of colorectal cancer for the highest versus lowest categories of blood circulating vitamin D levels was 0.75 (95% CI 0.58 to 0.97) up to 36.5 ng/mL in the Asian population. There was heterogeneity among the studies (I²=53.9%, P_{heterogeneity}=0.034). The dose-response meta-analysis indicated a significant linear relationship (P_{non-linearity}=0.11). An increment of 16 ng/mL in blood circulating vitamin D level corresponded to an OR of 0.79 (95% CI 0.64 to 0.97).

CONCLUSIONS

The results of this meta-analysis indicate that blood circulating vitamin D level is associated with decreased risk of colorectal cancer in Asian countries. The dose-response meta-analysis shows that the strength of this association among the Asian population is similar to that among the Western population. Our study suggests that the Asian population should improve nutritional status and maintain a higher level of blood circulating vitamin D.

The association of serum vitamin D-binding protein and 25-hydroxyvitamin D in pre-operative and post-operative colorectal cancer

Background

The association between vitamin D–binding protein (VDBP) and 25‐hydroxyvitamin D (25 (OH)D) with colorectal cancer (CRC) is still ambiguous. This study was to further investigate the relationship between serum VDBP, 25 (OH)D levels and the clinical and pathological features of patients with CRC.

Methods

Enzyme‐linked immunosorbent assay (ELISA) and chemiluminescence immunoassay were used to analyze the VDBP and 25(OH)D concentrations in serum. Pearson's correlation analysis was applied to evaluate the association between serum VDBP and 25(OH)D levels in CRC. Conditional logistic regression was performed to analyze the prediction value of serum VDBP or 25(OH)D as a risk factor for CRC.

Results

The serological levels of 25(OH)D in patients were significantly lower than in healthy individuals, while VDBP levels were significantly higher than in healthy controls. The serum VDBP in pre‐operative was significantly lower than in post‐operative samples, while the serum 25(OH)D from pre‐operative patients was significantly higher than post‐operative patients. Patients with tumors with higher stage and increased lymph node involvement had lower serum post‐operative VDBP levels. In addition, our results showed that the pre‐operative VDBP level is a risk factor of CRC.

Conclusions

The levels of serum 25(OH)D and VDBP were both associated with CRC. Thus, serum 25(OH)D and VDBP levels might be of value in evaluating the pathogenesis and risk of CRC in the future. Moreover, serum VDBP or 25(OH)D levels were associated with patient's clinical and pathological features providing data for risk and prognostic prediction.

Additively protective effects of vitamin D and calcium against colorectal adenoma incidence, malignant transformation and progression: A systematic review and meta-analysis

BACKGROUND

Colorectal cancer (CRC) exhibits a linear progression from normal colonic epithelium, adenoma initiation, carcinoma transformation and even to metastasis. Diet changes might influence carcinogenesis and prognosis. We aimed to determine the effects of vitamin D and calcium on colorectal adenoma incidence, malignancy development and prognosis.

METHODS

Systematic literature searches (PubMed, Embase, and Cochrane Library databases) and hand searches were performed by September 30, 2019. A random-effects model was adopted to pool relative ratios (RRs) for colorectal tumour incidence or hazard ratios (HRs) for CRC mortality. Stratified analyses were performed by gender, tumour location, calcium intake level and ethnic group.

RESULTS

Total 854,195 cases from 166 studies were included. The colorectal adenoma incidence was inversely correlated with the circulating 25-hydroxyvitamin D [25(OH)D] level (RR: 0.80, 95% CI: 0.71-0.89), vitamin D intake (RR: 0.87, 95% CI: 0.82-0.92) and calcium intake (RR: 0.86, 95% CI: 0.81-0.91). The CRC incidence was decreased by circulating 25(OH)D (RR: 0.67, 95% CI: 0.59-0.77), vitamin D intake (RR: 0.85, 95% CI: 0.78-0.93) and calcium intake (RR: 0.75, 95% CI: 0.70-0.79). High-level circulating 25(OH)D triggered better overall survival (HR: 0.67, 95% CI: 0.57-0.79) and CRC-specific survival (HR: 0.63, 95% CI: 0.53-0.74). Stratified analyses showed that vitamin D and calcium significantly suppressed colorectal tumour incidence among women. Left-sided CRC risk was reversely related to circulating 25(OH)D (RR: 0.60, 95% CI: 0.41-0.88) and vitamin D intake (RR: 0.73, 95% CI: 0.57-0.93). Circulating 25(OH)D decreased colorectal adenoma (RR: 0.63, 95% CI: 0.48-0.82) and CRC (RR: 0.69, 95% CI: 0.56-0.86) risk in populations with higher calcium intake. European and American populations benefited more from vitamin D intake against colorectal tumour. A significant dose-response relationship was observed between intake of vitamin D or calcium and colorectal tumour incidence.

CONCLUSIONS

Vitamin D and calcium play additively chemopreventive roles in colorectal adenoma incidence, malignant transformation and progression, especially for women and left-sided CRC patients.

A Critical Appraisal of Strategies to Optimize Vitamin D Status in Germany, a Population with a Western Diet

During the last decade, our scientific knowledge of the pleiotropic biological effects of vitamin D metabolites and their relevance to human health has expanded widely. Beyond the well-known key role of vitamin D in calcium homeostasis and bone health, it has been shown that vitamin D deficiency is associated with a broad variety of independent diseases, including several types of cancer, and with increased overall mortality. Moreover, recent findings have demonstrated biological effects of the vitamin D endocrine system that are not mediated via activation of the classical nuclear vitamin D receptor (VDR) by binding with high affinity to its corresponding ligand, the biologically active vitamin D metabolite 1,25-dihydroxyvitamin D (1,25(OH)₂D). In contrast, many of these new biological effects of vitamin D compounds, including regulation of the circadian clock and many metabolic functions, are mediated by other vitamin D metabolites, including 20-hydroxyvitamin D and 20,23-dihydroxyvitamin D, and involve their binding to the aryl hydrocarbon receptor (AhR) and retinoid-orphan receptor (ROR). In most populations, including the German population, UVB-induced cutaneous vitamin D production is the main source for fulfilling the human body’s requirements of vitamin D. However, this causes a dilemma because solar or artificial UVR exposure is associated with skin cancer risk. In addition to UVB-induced vitamin D production in skin, in humans, there are two other possible sources of vitamin D: from diet and supplements. However, only a few natural foods contain substantial amounts of vitamin D, and in most populations, the dietary source of vitamin D cannot fulfill the body´s requirements. Because an increasing body of evidence has convincingly demonstrated that vitamin D deficiency is very common worldwide, it is the aim of this paper to (i) give an update of the vitamin D status in a population with a western diet, namely, the German population, and to (ii) develop strategies to optimize the vitamin D supply that consider both the advantages as well as the disadvantages/risks of different approaches, including increasing vitamin D status by dietary intake, by supplements, or by UVB-induced cutaneous synthesis of vitamin D.

Vitamin D-binding protein (rs4588) T/T genotype is associated with anteroseptal myocardial infarction in coronary artery disease patients

Background

Cardiovascular diseases (CVD) are among leading causes of death worldwide and amongst CVD, coronary artery disease (CAD) accounts for almost half of all cardiovascular deaths as the most common cause of death in the developed world. Vitamin D and the vitamin D-binding protein (VDBP) have been studied as possible CAD pathogenesis factors but literature data provide opposing evidence on their role in CAD. Herein we aimed to present novel evidence on the association of two VDBP polymorphisms (rs4588) and (rs7041) with CAD in patients after acute myocardial infarction and study possible correlations of these polymorphisms with 25-hydroxyvitamin D [25(OH)D] serum levels.

Methods

The cross-section genotyping study included 155 subjects with CAD upon acute myocardial infarct and 104 control subjects. All patients and control group were Caucasians of European descent. VDBP polymorphisms (rs4588) and (rs7041) were studied by use of RT-PCR. Liquid chromatography, tandem mass spectrometry (LC-MS/MS) method was used for measurement of vitamin D in the serum.

Results

Association of the VDBP (rs4588) T/T genotype with CAD patients after acute MI and correlation of VDBP (rs4588) genotype G/G with higher levels of total vitamin D were found. No correlation of 25(OH)D serum levels with CAD were established but the multivariate logistic regression modelling enabled association of total vitamin D level and VDBP (rs4588) T/T genotype with CAD and anteroseptal myocardial infarction (ASMI) CAD occurrence.

Conclusions

Obtained data speak in favor to the VDBP (rs4588) T/T genotype as a susceptibility factor for anteroseptal myocardial infarction where the same genotype showed to be generally more prevalent in smokers.

Nanodiamond for Sample Preparation in Proteomics

Protein analysis of potential disease markers in blood is complicated by the fact that proteins in plasma show very different abundances. As a result, high-abundance proteins dominate the analysis, which often render the analysis of low-abundance proteins impossible. Depleting high-abundance proteins is one strategy to solve this problem. Here, we present, for the first time, a very simple approach based on selective binding of serum proteins to the surface of nanodiamonds. In our first proof-of-principle experiments, we were able to detect, on average, eight proteins that are present at a concentration of 1 ng/mL (instead of 0.5 ng/mL in the control without sample preparation). Remarkably, we detect proteins down to a concentration of 400 pg/mL after only one simple depletion step. Among the proteins we could analyze are also numerous disease biomarkers, including markers for multiple cancer forms, cardiovascular diseases, or Alzheimer's disease. Remarkably, many of the biomarkers we find also could not be detected with a state-of-the-art ultrahigh-performance liquid chromatography column (which depletes the 64 most-abundant serum proteins).

Sputum Proteomics Reveals a Shift in Vitamin D-binding Protein and Antimicrobial Protein Axis in Tuberculosis Patients

Existing understanding of molecular composition of sputum and its role in tuberculosis patients is variously limited to its diagnostic potential. We sought to identify infection induced sputum proteome alteration in active/non tuberculosis patients (A/NTB) and their role in altered lung patho-physiology. Out of the study population (n = 118), sputum proteins isolated from discovery set samples (n = 20) was used for an 8-plex isobaric tag for relative and absolute concentration analysis. A minimum set of protein with at least log₂(ATB/NTB) >±1.0 in ATB was selected as biosignature and validated in 32 samples. Predictive accuracy was calculated from area under the receiver operating characteristic curve (AUC of ROC) using a confirmatory set (n = 50) by Western blot analysis. Mass spectrometry analysis identified a set of 192 sputum proteins, out of which a signature of β-integrin, vitamin D binding protein:DBP, uteroglobin, profilin and cathelicidin antimicrobial peptide was sufficient to differentiate ATB from NTB. AUC of ROC of the biosignature was calculated to 0.75. A shift in DBP-antimicrobial peptide (AMP) axis in the lungs of tuberculosis patients is observed. The identified sputum protein signature is a promising panel to differentiate ATB from NTB groups and suggest a deregulated DBP-AMP axis in lungs of tuberculosis patients.

Vitamin D Status Is Not Associated with Risk of Early Menopause

Background

Early natural menopause, the cessation of ovarian function before age 45 y, is positively associated with cardiovascular disease and other conditions. Dietary vitamin D intake has been inversely associated with early menopause; however, no previous studies have evaluated risk with regard to plasma 25-hydroxyvitamin D [25(OH)D] concentrations.

Objective

We prospectively evaluated associations of total and free 25(OH)D and vitamin D-binding protein (VDBP) concentrations and the risk of early menopause in a case-control study nested within the Nurses' Health Study II (NHS2). We also considered associations of 25(OH)D and VDBP with anti-Müllerian hormone (AMH) concentrations.

Methods

The NHS2 is a prospective study in 116,430 nurses, aged 25-42 y at baseline (1989). Premenopausal plasma blood samples were collected between 1996 and 1999, from which total 25(OH)D and VDBP concentrations were measured and free 25(OH)D concentrations were calculated. Cases experienced menopause between blood collection and age 45 y (n = 328) and were matched 1:1 by age and other factors to controls who experienced menopause after age 48 y (n = 328). Conditional logistic regression models were used to estimate ORs and 95% CIs for early menopause according to each biomarker. Generalized linear models were used to estimate AMH geometric means according to each biomarker.

Results

After adjusting for smoking and other factors, total and free 25(OH)D were not associated with early menopause. Quartile 4 compared with quartile 1 ORs were 1.04 (95% CI: 0.60, 1.81) for total 25(OH)D and 0.70 (95% CI: 0.41, 1.20) for free 25(OH)D. 25(OH)D was unrelated to AMH concentrations. VDBP was positively associated with early menopause; the OR comparing the highest with the lowest quartile of VDBP was 1.80 (95% CI: 1.09, 2.98).

Conclusions

Our findings suggest that total and free 25(OH)D are not importantly related to the risk of early menopause. VDBP may be associated with increased risk, but replication is warranted.

Serum vitamin D levels correlate with the presence and histological grading of colorectal adenomas in peri and postmenopausal women

BACKGROUND & AIMS

Vitamin D is known to modulate immune function and proliferation. Higher vitamin D [25(OH)D₃] serum levels have been reported to have protective effects on adenoma detection and colorectal cancer (CRC) development and survival.

METHODS

This retrospective cohort study included 315 peri and post-menopausal women submitted to opportunistic colorectal and osteoporosis screening at the gynaecology outpatient clinic of a tertiary medical centre between 2004 and 2015. Colonoscopy findings were correlated with 25(OH)D₃ and PTH serum levels, and subsequently adjusted in a multivariate logistic regression model. Confounding factors included demographic and colorectal risk factors, pharmacological therapies and bone densitometry metrics.

RESULTS

A total of 77 lesions were identified in 66 patients. Vitamin D insufficiency (<30 ng/mL) and deficiency (<20 ng/mL) were identified in 79.4% and 35.2% of patients, respectively. In univariate analysis, lower levels of 25(OH)D₃ were associated with polyp, adenoma and advanced adenoma detection. After adjusting for confounders, an association with polyps could not be observed, but a trend towards a negative correlation with adenoma detection was found (adjusted OR: 0.96; 95% CI 0.92-1.00; p = 0.083). Regarding advanced adenoma detection, 25(OH)D₃ (adjusted OR: 0.86; 95% CI 0.77-0.97; p = 0.013) proved to be an independent predictive factor. No association was found between 25(OH)D₃ levels and lesion detection site.

CONCLUSION

The association of 25(OH)D₃ serum levels with colorectal lesions seems to be restricted to adenomatous lesions and is influenced by histological grading. Vitamin D may be a valuable biomarker for optimization of risk stratification in group-specific CRC screening protocols.

Why should we measure free 25(OH) vitamin D?

Vitamin D, either in its D₂ or D₃ form, is essential for normal human development during intrauterine life, kidney function and bone health. Vitamin D deficiency has also been linked to cancer development and some autoimmune diseases. Given this huge impact of vitamin D on human health, it is important for daily clinical practice and clinical research to have reliable tools to judge on the vitamin D status. The major circulating form of vitamin D is 25-hydroxyvitamin D (25(OH)D), although it is not the most active metabolite, the concentrations of total 25-hydroxyvitamin D in the serum are currently routinely used in clinical practice to assess vitamin D status. In the circulation, vitamin D - like other steroid hormones - is bound tightly to a special carrier - vitamin D-binding protein (DBP). Smaller amounts are bound to blood proteins - albumin and lipoproteins. Only very tiny amounts of the total vitamin D are free and potentially biologically active. Currently used vitamin D assays do not distinguish between the three forms of vitamin D - DBP-bound vitamin D, albumin-bound vitamin D and free, biologically active vitamin D. Diseases or conditions that affect the synthesis of DBP or albumin thus have a huge impact on the amount of circulating total vitamin D. DBP and albumin are synthesized in the liver, hence all patients with an impairment of liver function have alterations in their total vitamin D blood concentrations, while free vitamin D levels remain mostly constant. Sex steroids, in particular estrogens, stimulate the synthesis of DBP. This explains why total vitamin D concentrations are higher during pregnancy as compared to non-pregnant women, while the concentrations of free vitamin D remain similar in both groups of women. The vitamin D-DBP as well as vitamin D-albumin complexes are filtered through the glomeruli and re-uptaken by megalin in the proximal tubule. Therefore, all acute and chronic kidney diseases that are characterized by a tubular damage, are associated with a loss of vitamin D-DBP complexes in the urine. Finally, the gene encoding DBP protein is highly polymorphic in different human racial groups. In the current review, we will discuss how liver function, estrogens, kidney function and the genetic background might influence total circulating vitamin D levels and will discuss what vitamin D metabolite is more appropriate to measure under these conditions: free vitamin D or total vitamin D.

Prognostic value of circulating vitamin D binding protein, total, free and bioavailable 25-hydroxy vitamin D in patients with colorectal cancer

Numerous studies have suggested that there was a significantly positive association between circulating total 25-hydroxyvitamin D (25(OH)D) and survival in colorectal cancer patients. Moreover, plasma vitamin D was also found significantly associated with the concentration of vitamin D binding protein (VDBP). However, there was no paper to clarify the prognostic value of VDBP, free and bioavailable 25(OH)D in colorectal carcinogenesis. The aim of this study was to comprehensively assess the prognostic value of VDBP, total, free and bioavailable 25(OH)D in stage I-III colorectal cancer patients. A total of 206 colorectal cancer patients were enrolled in this prospective study. Preoperative plasma total 25(OH)D and VDBP concentrations were measured by direct enzyme-linked immunosorbent assay, and albumin concentration was measured by Beckman automatic biochemical analyzer. Free and bioavailable 25(OH)D concentrations were calculated based on the concentrations of plasma VDBP, total 25(OH) D and albumin. X-title program was used to determine the optimal cut-off values of VDBP, total, free and bioavailable 25(OH)D. Results showed that elevated free and bioavailable 25(OH)D were significantly associated with better 5-year overall survival (OS) by univariate analysis. By multivariate cox analysis, we also found that the high level of free 25(OH)D (HR = 0.442, 95%CI = 0.238–0.819, P < 0.010) could be identified as an independent factor for better OS. In conclusion, our study suggested that higher levels of free and bioavailable 25(OH)D were associated with better OS in stage I-III colorectal cancer patients. Moreover, free 25(OH)D could be considered as an independent prognostic biomarker for OS.

Plasma 25-hydroxyvitamin D concentration and subsequent risk of total and site specific cancers in Japanese population: large case-cohort study within Japan Public Health Center-based Prospective Study cohort

OBJECTIVE

To evaluate the association between pre-diagnostic circulating vitamin D concentration and the subsequent risk of overall and site specific cancer in a large cohort study.

DESIGN

Nested case-cohort study within the Japan Public Health Center-based Prospective Study cohort.

SETTING

Nine public health centre areas across Japan.

PARTICIPANTS

3301 incident cases of cancer and 4044 randomly selected subcohort participants.

EXPOSURE

Plasma concentration of 25-hydroxyvitamin D measured by enzyme immunoassay. Participants were divided into quarters based on the sex and season specific distribution of 25-hydroxyvitamin D among subcohorts. Weighted Cox proportional hazard models were used to calculate the multivariable adjusted hazard ratios for overall and site specific cancer across categories of 25-hydroxyvitamin D concentration, with the lowest quarter as the reference.

MAIN OUTCOME MEASURE

Incidence of overall or site specific cancer.

RESULTS

Plasma 25-hydroxyvitamin D concentration was inversely associated with the risk of total cancer, with multivariable adjusted hazard ratios for the second to fourth quarters compared with the lowest quarter of 0.81 (95% confidence interval 0.70 to 0.94), 0.75 (0.65 to 0.87), and 0.78 (0.67 to 0.91), respectively (P for trend=0.001). Among the findings for cancers at specific sites, an inverse association was found for liver cancer, with corresponding hazard ratios of 0.70 (0.44 to 1.13), 0.65 (0.40 to 1.06), and 0.45 (0.26 to 0.79) (P for trend=0.006). A sensitivity analysis showed that alternately removing cases of cancer at one specific site from total cancer cases did not substantially change the overall hazard ratios.

CONCLUSIONS

In this large prospective study, higher vitamin D concentration was associated with lower risk of total cancer. These findings support the hypothesis that vitamin D has protective effects against cancers at many sites.

Vitamin D-Binding Protein Enhances Epithelial Ovarian Cancer Progression by Regulating the Insulin-like Growth Factor-1/Akt Pathway and Vitamin D Receptor Transcription

Purpose: Malignant ascites of epithelial ovarian cancer (EOC) helps identify prognostic biomarkers or mechanisms of tumor progression. Vitamin D-binding protein (DBP) was revealed to be upregulated in EOC ascites in our previous proteomic study. Here, we examined the role of DBP in EOC.Experimental Design: We analyzed ascites, serum, and tissue samples of patients with newly diagnosed EOC to determine the prognostic effects of DBP. We verified DBP function using orthotopic animal models and DBP regulation in ovarian cancer cell lines.Results: Elevated ascitic DBP was significantly associated with poor response to chemotherapy, short progression-free interval, increased cancer progression, and death. Ascitic DBP overexpression was an independent unfavorable biomarker for progression-free survival; DBP overexpression in cancerous tissue was significantly related to chemoresistance. In vivo and in vitro investigations demonstrated an important role for DBP in ovarian cancer progression. Orthotopic model mice inoculated with DBP knockdown ovarian cancer cells displayed a significant reduction in tumor formation, malignant cell number, ascitic DBP levels, invasiveness, and metastasis, and increased survival compared with controls. In presence of vitamin D receptor (VDR), DBP promoted cell aggression (invasion and doubling time) via activation of the insulin-like growth factor-1/insulin-like growth factor-binding protein-2/Akt axis, and induced suppression of vitamin D-responsive genes. A NF-κB p65-binding site in the VDR promoter was identified as a major determinant of DBP-dependent VDR promoter activation.Conclusions: This study highlights the importance of DBP in ovarian tumor progression and the potential application of DBP as a therapeutic target for EOC. Clin Cancer Res; 24(13); 3217-28. ©2018 AACR.

Concerning the vitamin D reference range: pre-analytical and analytical variability of vitamin D measurement

Unlike other vitamins, the vitamin D concentration in blood varies cyclically over the course of the year in relation to genetic (gender, ethnicity, polymorphisms) and environmental factors (sunlight exposure, diet, food-related or direct vitamin D supplementation, skin pigmentation). Although the major diagnostics manufacturers have recently developed improved automated 25-hydroxy vitamin D immunoassays, the intra- and inter-laboratory variability is still high (especially at low vitamin D concentrations) which might lead to incorrect vitamin D deficiency/insufficiency diagnosis. Moreover, despite recent efforts to standardize the assay and minimize its variability, the current bias for measured vitamin D concentrations is often still above the desirable ± 10% criterion. Because the implications of low vitamin D concentrations in non-skeletal diseases are still partially unknown, international guideline recommendations for establishing meaningful ranges, at any time over the course of the year, irrespective not only of environmental and personal factors but also of instrumental variability, are needed. In this review, we discuss the main factors that influence the variability of vitamin D concentrations and whether a centile curve, individually calculated by a theoretical equation considering such factors, might be better suited than a fixed limit to assess abnormal vitamin D concentrations in otherwise healthy subjects. Vitamin D reference ranges during pregnancy, childhood, or diagnosed illnesses, which merit separate discussion, are beyond the scope of this review.

Vitamin D metabolites in captivity? Should we measure free or total 25(OH)D to assess vitamin D status?

There is general consensus that serum 25(OH)D is the best biochemical marker for nutritional vitamin D status. Whether free 25(OH)D would be a better marker than total 25(OH)D is so far unclear. Free 25(OH)D can either be calculated based on the measurement of the serum concentrations of total 25(OH)D, vitamin D-binding protein (DBP), albumin, and the affinity between 25(OH)D and its binding proteins in physiological situations. Free 25(OH)D can also be measured directly by equilibrium dialysis, ultrafitration or immunoassays. During the vitamin D workshop held in Boston in March 2016, a debate was organized about the measurements and clinical value of free 25(OH)D, and this debate is summarized in the present manuscript. Overall there is consensus that most cells apart from the renal tubular cells are exposed to free rather than to total 25(OH)D. Therefore free 25(OH)D may be highly relevant for the local production and action of 1,25(OH)₂D. During the debate it became clear that there is a need for standardization of measurements of serum DBP and of direct measurements of free 25(OH)D. There seems to be very limited genetic or racial differences in DBP concentrations or (probably) in the affinity of DBP for its major ligands. Therefore, free 25(OH)D is strongly correlated to total 25(OH)D in most normal populations. Appropriate studies are needed to define the clinical implications of free rather than total 25(OH)D in normal subjects and in disease states. Special attention is needed for such studies in cases of abnormal DBP concentrations or when one could expect changes in its affinity for its ligands.

Total and Free Circulating Vitamin D and Vitamin D-Binding Protein in Relation to Colorectal Cancer Risk in a Prospective Study of African Americans

Background: Previous studies rarely evaluated the associations between vitamin D-binding protein and free vitamin D with colorectal cancer risk. We assessed these biomarkers and total 25-hydroxyvitamin D in relation to colorectal cancer risk in a sample of African Americans.Methods: Cases comprised 224 African American participants of the Southern Community Cohort Study diagnosed with incident colorectal cancer. Controls (N = 440) were selected through incidence density sampling and matched to cases on age, sex, and race. Conditional logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (CI) for associations between biomarker levels and colorectal cancer risk.Results: Vitamin D was inversely associated with colorectal cancer risk where the OR per-SD increase in total and free 25-hydroxyvitamin D were 0.82 (95% CI, 0.66-1.02) and 0.82 (95% CI, 0.66-1.01), respectively. Associations were most apparent among cases diagnosed >3 years after blood draw: ORs for the highest tertile versus the lowest were 0.69 (95% CI, 0.21-0.93) for total 25-hydroxyvitamin D and 0.71 (95% CI, 0.53-0.97) for free 25-hydroxyvitamin D. Inverse associations were seen in strata defined by sex, BMI, and anatomic site, although not all findings were statistically significant. Vitamin D-binding protein was not associated with colorectal cancer risk.Conclusions: Our findings suggest that total and free 25-hydroxyvitamin D may be inversely associated with colorectal cancer risk among African Americans.Impact: These findings highlight a potential role for vitamin D in colorectal cancer prevention in African Americans. Cancer Epidemiol Biomarkers Prev; 26(8); 1242-7. ©2017 AACR.

25-Hydroxyvitamin D Status and Risk for Colorectal Cancer and Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis of Epidemiological Studies

Epidemiological evidence suggests an association between low vitamin D status and risk for various outcomes including cardiovascular diseases, cancer, and type 2 diabetes mellitus (T2DM). Analyzing serum 25-hydroxyvitamin D [25(OH)D] is the most established means to evaluate an individual's vitamin D status. However, cutoff values for 25(OH)D insufficiency as well as for optimal 25(OH)D levels are controversial. This systematic review critically summarizes the epidemiological evidence regarding 25(OH)D levels and the risk for colorectal cancer and T2DM. The meta-analytical calculation revealed a pooled relative risk (RR) of 0.62 (CI 0.56-0.70; I² = 14.7%) for colorectal cancer and an RR of 0.66 (CI 0.61-0.73; I² = 38.6%) for T2DM when comparing individuals with the highest category of 25(OH)D with those in the lowest. A dose-response analysis showed an inverse association between 25(OH)D levels and RR for both outcomes up to concentrations of about 55 ng/mL for colorectal cancer and about 65 ng/mL for T2DM. At still higher 25(OH)D levels the RR increases slightly, consistent with a U-shaped association. In conclusion, a higher 25(OH)D status is associated with a lower risk for colorectal cancer and T2DM; however, this advantage is gradually lost as levels increase beyond 50-60 ng/mL.

Association between serum levels of bioavailable vitamin D and negative symptoms in first-episode psychosis

Total vitamin D levels had been commonly reported to be lowered in patients with chronic psychotic illnesses in countries from the higher latitudes. However, studies on patients with first episode psychosis (FEP) are limited. In this study we investigated serum concentrations of total and bioavailable vitamin D levels in FEP patients compared to healthy controls and the association between symptom severity and vitamin D components. A total of 31 FEP patients and 31 healthy controls were recruited from Institute of Mental Health, Singapore. FEP patients were identified using Structured Clinical Interview for DSM-IV Axis I disorders (SCID-1) and severity symptoms were assessed using the positive and negative syndrome scale (PANSS). Sera from participants were analyzed for total vitamin D, vitamin D-binding protein (DBP) and bioavailable vitamin D. Linear regressions were performed to examine the associations between serum total and bioavailable vitamin D and the PANSS subscales. Current study noted a significantly lower bioavailable vitamin D was in the FEP group and an association between bioavailable vitamin D and negative symptoms in FEP patients in a population with a consistent supply of sun exposure throughout the year.

Vitamin D-binding protein and free vitamin D concentrations in acromegaly

Free 25-hydroxyvitamin D [25(OH)D] is suggested to be important in the determination of vitamin D deficiency, since vitamin D-binding protein (VDBP) may affect total 25(OH)D levels. There are no data about free 25(OH)D concentrations in acromegaly. We aimed to investigate serum VDBP and total and free 25(OH)D levels in patients with acromegaly in comparison with control subjects. We recruited 54 patients with acromegaly and 32 control subjects who were similar according to age, gender, and body mass index. Serum VDBP levels were found to be increased in patients with acromegaly compared to control subjects [90.35 (72.45-111.10) vs. 69.52 (63.89-80.13) mg/l, p = 0.001]. There was statistically no significant difference in serum total 25(OH)D levels between the patients with acromegaly and control subjects [18.63 (13.35-27.73) vs. 22.51 (19.20-28.96) ng/ml, p = 0.05]. Free 25(OH)D levels were significantly decreased in patients with acromegaly compared to control subjects [14.55 (10.45-21.45) vs. 17.75 (15.30-23.75) pg/ml, p = 0.03]. Free 25(OH)D levels correlated positively with total 25(OH)D (p = 0.0001) and HDL cholesterol (p = 0.04) and negatively with fasting blood glucose (p = 0.04). Our findings indicate that VDBP is increased and free 25(OH)D is decreased in acromegaly, while there is no significant alteration in total 25(OH)D.

Serum Vitamin D is Not Helpful for Predicting Prostate Cancer Aggressiveness Compared with the Prostate Health Index

PURPOSE

We evaluated the usefulness of serum 25-hydroxyvitamin D as a marker of aggressive prostate cancer and for active surveillance compared to PHI (Prostate Health Index).

MATERIALS AND METHODS

Of 480 prospectively biopsied men 222 had prostate cancer and 258 had no evidence of malignancy. In all men prostate specific antigen was less than 20 ng/ml. We measured 25-hydroxyvitamin D, prostate specific antigen, free prostate specific antigen and -2proPSA using a commercially available immunoassay system. PHI was calculated according to the equation, -2proPSA/free prostate specific antigen × √PSA. We determined 25-hydroxyvitamin D using a 2-step competitive binding immunoenzymatic vitamin D assay.

RESULTS

The 25-hydroxyvitamin D concentrations were not associated with Gleason grade according to the 2014 ISUP (International Society of Urological Pathology) consensus conference Gleason grading system. PHI values were higher with increasing Gleason grade. Median 25-hydroxyvitamin D did not differ between men with prostate cancer vs no evidence of malignancy (50.6 vs 48.2 nmol/l, p = 0.192) or in ISUP Gleason subgroups despite seasonal variations of 25-hydroxyvitamin D. However, PHI values significantly differed between the subgroup with no evidence of malignancy and all Gleason subgroups (p <0.0001). The ROCs of all men revealed an advantage of PHI over 25-hydroxyvitamin D (AUC 0.78 vs 0.535, p <0.0001). PHI could also significantly better separate patients with no evidence of malignancy from those with nonaggressive disease (ISUP Gleason grade 1) from those with aggressive prostate cancer (ISUP Gleason grades 2-5).

CONCLUSIONS

It remains highly improbable that 25-hydroxyvitamin D could be used as decision or selection marker for aggressive prostate cancer or for active surveillance compared to accepted markers, as recently suggested.

Renal cell carcinoma: Review of etiology, pathophysiology and risk factors

BACKGROUND AND AIMS

The global incidence of renal cell cancer is increasing annually and the causes are multifactorial. Early diagnosis and successful urological procedures with partial or total nephrectomy can be life-saving. However, only up to 10% of RCC patients present with characteristic clinical symptoms. Over 60% are detected incidentally in routine ultrasound examination. The question of screening and preventive measures greatly depends on the cause of the tumor development. For the latter reason, this review focuses on etiology, pathophysiology and risk factors for renal neoplasm.

METHODS

A literature search using the databases Medscape, Pubmed, UpToDate and EBSCO from 1945 to 2015.

RESULTS AND CONCLUSIONS

Genetic predisposition/hereditary disorders, obesity, smoking, various nephrotoxic industrial chemicals, drugs and natural/manmade radioactivity all contribute and enviromental risks are a serious concern in terms of prevention and the need to screen populations at risk. Apropos treatment, current oncological research is directed to blocking cancer cell division and inhibiting angiogenesis based on a knowledge of molecular pathways.

Association between pre-miR-27a functional polymorphism and risk of colorectal cancer in north Chinese Han population

MicroRNA-27a (miR-27a) is deemed as an oncogene in malignancies including colorectal cancer (CRC), and rs895819 within pre-miR-27a may affect its secondary structure, leading to its aberrant expression and dysfunction of its targeted gene. We investigated genotype and allele frequencies of the locus in 412 I–III stage CRC cases and 412 age- and sex-matched healthy individuals to explore the possible association between them in the north of Chinese population. The results showed that frequencies of alleles A and G and genotypes GG, AG, and AA of the locus were 65.7%, 34.3%, 17.0%, 34.7%, and 48.3% in cases and 69.9%, 30.1%, 9.9%, 40.2%, and 49.8% in controls, respectively. GG genotype of the locus was positively associated with an increased risk of CRC in codominant (P=0.01, adjusted odds ratio =1.541, 95% confidence interval =1.110–2.239 for genotype GG vs AA) and recessive (P=0.003, adjusted odds ratio =1.855, 95% confidence interval =1.221–2.786 for genotype GG vs AA/GA) models, indicating that GG genotype of the locus might increase susceptibility to CRC. Moreover, genotypes AG and GG and allele G were significantly associated with III stage (P<0.001, P<0.001, and P=0.001, respectively), suggesting that the locus was associated with the progression of CRC. These results suggested that rs895819 within pre-miR-27a was involved in colorectal carcinogenesis and progression, genotype GG of the locus might be a susceptible factor for CRC, and allele G and allele G carrier (genotypes AG and GG) could predict CRC progression in north Chinese Han population.

Low 25-hydroxyvitamin D, but not the bioavailable fraction of 25-hydroxyvitamin D, is a risk factor for multiple sclerosis

BACKGROUND AND PURPOSE

Low 25-hydroxyvitamin D [25(OH)D] levels correlate with higher disease activity in patients with multiple sclerosis (MS). However, it is not clear whether low 25(OH)D levels directly contribute to increased disease activity or merely represent a consequence of reduced endogenous vitamin D synthesis in more disabled MS patients. Furthermore, recent data suggest that bioavailable vitamin D, which also integrates the levels of vitamin D binding proteins and albumin, could be a biologically more relevant parameter than 25(OH)D.

METHODS

Measured de-seasonalized 25(OH)D3 and vitamin D binding protein and calculated bioavailable and free vitamin D were compared in the baseline serum samples of 76 patients with clinically isolated syndrome enrolled in a longitudinal observational study and in 76 age- and sex-matched healthy controls (HC).

RESULTS

25(OH)D3 levels were lower in patients with clinically isolated syndrome (P = 0.002) than in HC, and more patients (8/76, 10.5%) than HC (1/76, 1.3%) had 25(OH)D3 levels <25 nmol/l (P = 0.03). In contrast, levels of 25(OH)D2, vitamin D binding protein and calculated levels of free and bioavailable vitamin D did not differ between the two groups.

CONCLUSIONS

Lower 25(OH)D3 levels already in the earliest phase of disease and in clinically hardly affected patients suggest that low 25(OH)D3 levels are rather a risk factor for than a consequence of MS. Nevertheless, because bioavailable vitamin D levels did not differ between the two groups, the mechanism underlying the association of 25(OH)D3 and MS does not appear to be related to reduced bioavailability of vitamin D.