Development of In Vitro and In Vivo Evaluation Systems for Vitamin D Derivatives and Their Application to Drug Discovery

We have developed an in vitro system to easily examine the affinity for vitamin D receptor (VDR) and CYP24A1-mediated metabolism as two methods of assessing vitamin D derivatives. Vitamin D derivatives with high VDR affinity and resistance to CYP24A1-mediated metabolism could be good therapeutic agents. This system can effectively select vitamin D derivatives with these useful properties. We have also developed an in vivo system including a Cyp27b1-gene-deficient rat (a type I rickets model), a Vdr-gene-deficient rat (a type II rickets model), and a rat with a mutant Vdr (R270L) (another type II rickets model) using a genome editing method. For Cyp27b1-gene-deficient and Vdr mutant (R270L) rats, amelioration of rickets symptoms can be used as an index of the efficacy of vitamin D derivatives. Vdr-gene-deficient rats can be used to assess the activities of vitamin D derivatives specialized for actions not mediated by VDR. One of our original vitamin D derivatives, which displays high affinity VDR binding and resistance to CYP24A1-dependent metabolism, has shown good therapeutic effects in Vdr (R270L) rats, although further analysis is needed.

Vitamin K2 Awareness in Sun-Protected Patients Supplementing With Vitamin D

Dermatologists often recommend vitamin D for sun-protected patients. Most patients are not aware of the key role vitamin K2 plays in vitamin D metabolism and do not receive sufficient dietary vitamin K2. A survey of 50 sun-protecting patients shows 4/50 understood the role of vitamin K2 and 1/50 was supplementing vitamin K2. Therefore, counseling on vitamin K2 supplementation may be of benefit to sun-protected dermatology patients. J Drugs Dermatol. 2021;20(2):228-229. doi:10.36849/JDD.5829.

Vitamin A and D Absorption in Adults with Metabolic Syndrome versus Healthy Controls: A Pilot Study Utilizing Targeted and Untargeted LC-MS Lipidomics

SCOPE

Persons with metabolic syndrome (MetS) absorb less vitamin E than healthy controls. It is hypothesized that absorption of fat-soluble vitamins (FSV) A and D2 would also decrease with MetS status and that trends would be reflected in lipidomic responses between groups.

METHODS AND RESULTS

Following soymilk consumption (501 IU vitamin A, 119 IU vitamin D2 ), the triglyceride-rich lipoprotein fractions (TRL) from MetS and healthy subjects (n = 10 age- and gender-matched subjects/group) are assessed using LC-MS/MS. Absorption is calculated using area under the time-concentration curves (AUC) from samples collected at 0, 3, and 6 h post-ingestion. MetS subjects have ≈6.4-fold higher median vitamin A AUC (retinyl palmitate) versus healthy controls (P = 0.07). Vitamin D2 AUC is unaffected by MetS status (P = 0.48). Untargeted LC-MS lipidomics reveals six phospholipids and one cholesterol ester with concentrations correlating (r = 0.53-0.68; P < 0.001) with vitamin A concentration.

CONCLUSIONS

The vitamin A-phospholipid association suggests increased hydrolysis by PLB, PLRP2, and/or PLA2 IB may be involved in the trend in higher vitamin A bioavailability in MetS subjects. Previously observed differences in circulating levels of these vitamins are likely not due to absorption. Alternate strategies should be investigated to improve FSV status in MetS.

Differences in 25-Hydroxyvitamin D Clearance by eGFR and Race: A Pharmacokinetic Study

BACKGROUND

Conversion of 25-hydroxyvitamin D (25[OH]D) to the active form of vitamin D occurs primarily in the kidney. Observational studies suggest 25(OH)D clearance from the circulation differs by kidney function and race. However, these potential variations have not been tested using gold-standard methods.

METHODS

We administered intravenous, deuterated 25(OH)D3 (d-25[OH]D3) in a pharmacokinetic study of 87 adults, including 43 with normal eGFR (≥60 ml/min per 1.73 m2), 24 with nondialysis CKD (eGFR <60 ml/min per 1.73 m2), and 20 with ESKD treated with hemodialysis. We measured concentrations of d-25(OH)D3 and deuterated 24,25-dihydroxyvitamin D3 at 5 minutes and 4 hours after administration, and at 1, 4, 7, 14, 21, 28, 42, and 56 days postadministration. We calculated 25(OH)D clearance using noncompartmental analysis of d-25(OH)D3 concentrations over time. We remeasured 25(OH)D clearance in a subset of 18 participants after extended oral vitamin-D3 supplementation.

RESULTS

The mean age of the study cohort was 64 years; 41% were female, and 30% were Black. Mean 25(OH)D clearances were 360 ml/d, 313 ml/d, and 263 ml/d in participants with normal eGFR, CKD, and kidney failure, respectively (P=0.02). After adjustment for age, sex, race, and estimated blood volume, lower eGFR was associated with reduced 25(OH)D clearance (β=-17 ml/d per 10 ml/min per 1.73 m2 lower eGFR; 95% CI, -21 to -12). Black race was associated with higher 25(OH)D clearance in participants with normal eGFR, but not in those with CKD or kidney failure (P for interaction=0.05). Clearance of 25(OH)D before versus after vitamin-D3 supplementation did not differ.

CONCLUSIONS

Using direct pharmacokinetic measurements, we show that 25(OH)D clearance is reduced in CKD and may differ by race.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

Clearance of 25-hydroxyvitamin D in Chronic Kidney Disease (CLEAR), NCT02937350; Clearance of 25-hydroxyvitamin D3 During Vitamin D3 Supplementation (CLEAR-PLUS), NCT03576716.

Ultra-Marathon-Induced Increase in Serum Levels of Vitamin D Metabolites: A Double-Blind Randomized Controlled Trial

Purpose: While an increasing number of studies demonstrate the importance of vitamin D for athletic performance, the effects of any type of exercise on vitamin D metabolism are poorly characterized. We aimed to identify the responses of some vitamin D metabolites to ultra-marathon runs. Methods: A repeated-measures design was implemented, in which 27 amateur runners were assigned into two groups: those who received a single dose of vitamin D₃ (150,000 IU) 24 h before the start of the marathon (n = 13) and those (n = 14) who received a placebo. Blood samples were collected 24 h before, immediately after, and 24 h after the run. Results: In both groups of runners, serum 25(OH)D₃, 24,25(OH)₂D₃, and 3-epi-25(OH)D₃ levels significantly increased by 83%, 63%, and 182% after the ultra-marathon, respectively. The increase was most pronounced in the vitamin D group. Body mass and fat mass significantly decreased after the run in both groups. Conclusions: Ultra-marathon induces the mobilization of vitamin D into the blood. Furthermore, the 24,25(OH)₂D₃ and 3-epi-25(OH)D₃ increases imply that the exercise stimulates vitamin D metabolism.

Vitamin D, Autoimmune Disease and Rheumatoid Arthritis

Vitamin D has been reported to influence physiological systems that extend far beyond its established functions in calcium and bone homeostasis. Prominent amongst these are the potent immunomodulatory effects of the active form of vitamin D, 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3). The nuclear vitamin D receptor (VDR) for 1,25-(OH)2D3 is expressed by many cells within the immune system and resulting effects include modulation of T cell phenotype to suppress pro-inflammatory Th1 and Th17 CD4+ T cells and promote tolerogenic regulatory T cells. In addition, antigen-presenting cells have been shown to express the enzyme 1α-hydroxylase that converts precursor 25-hydroxyvitamin D3 (25-OHD3) to 1,25-(OH)2D3, so that immune microenvironments are able to both activate and respond to vitamin D. As a consequence of this local, intracrine, system, immune responses may vary according to the availability of 25-OHD3, and vitamin D deficiency has been linked to various autoimmune disorders including rheumatoid arthritis (RA). The aim of this review is to explore the immune activities of vitamin D that impact autoimmune disease, with specific reference to RA. As well as outlining the mechanisms linking vitamin D with autoimmune disease, the review will also describe the different studies that have linked vitamin D status to RA, and the current supplementation studies that have explored the potential benefits of vitamin D for prevention or treatment of RA. The overall aim of the review is to provide a fresh perspective on the potential role of vitamin D in RA pathogenesis and treatment.

Genetic variation in GC and CYP2R1 affects 25-hydroxyvitamin D concentration and skeletal parameters: A genome-wide association study in 24-month-old Finnish children

Vitamin D is important for normal skeletal homeostasis, especially in growing children. There are no previous genome-wide association (GWA) studies exploring genetic factors that influence vitamin D metabolism in early childhood. We performed a GWA study on serum 25-hydroxyvitamin D (25(OH)D) and response to supplementation in 761 healthy term-born Finnish 24-month-old children, who participated in a randomized clinical trial comparing effects of 10 μg and 30 μg of daily vitamin D supplementation from age 2 weeks to 24 months. Using the Illumina Infinium Global Screening Array, which has been optimized for imputation, a total of 686085 markers were genotyped across the genome. Serum 25(OH)D was measured at the end of the intervention at 24 months of age. Skeletal parameters reflecting bone strength were determined at the distal tibia at 24 months using peripheral quantitative computed tomography (pQCT) (data available for 648 children). For 25(OH)D, two strong GWA signals were identified, localizing to GC (Vitamin D binding protein) and CYP2R1 (Vitamin D 25-hydroxylase) genes. The GWA locus comprising the GC gene also associated with response to supplementation. Further evidence for the importance of these two genes was obtained by comparing association signals to gene expression data from the Genotype-Tissue Expression project and performing colocalization analyses. Through the identification of haplotypes associated with low or high 25(OH)D concentrations we used a Mendelian randomization approach to show that haplotypes associating with low 25(OH)D were also associated with low pQCT parameters in the 24-month-old children. In this first GWA study on 25(OH)D in this age group we show that already at the age of 24 months genetic variation influences 25(OH)D concentrations and determines response to supplementation, with genome-wide significant associations with GC and CYP2R1. Also, the dual association between haplotypes, 25(OH)D and pQCT parameters gives support for vertical pleiotropy mediated by 25(OH)D.

Vitamin D status in a monocentric cohort of systemic lupus erythematosus (SLE) patients and correlations with clinical and immunological profile

INTRODUCTION

Numerous studies have found that a majority of systemic lupus erythematosus (SLE) patients have suboptimal vitamin D levels. The major contributory factor is most likely attributed to sun protection measures in order to avoid SLE flares. The objectives of this research included the assessment of vitamin D status and its association with clinical manifestations of SLE, cardiovascular risk factors, autoantibodies, SLE disease activity and damage accrual.

METHOD

This retrospective study involved SLE patients who attended the Rheumatology Clinic at the Hospital Kuala Lumpur from January 2014 to December 2016. Vitamin D was categorised as normal, insufficient or deficient, and the clinical variables were compared across vitamin D categories with chi-squared tests and Pearson correlation coefficient.

RESULTS

We included 216 patients. The mean 25(OH)D concentration was 51.3(Standard Deviation; SD 14.8) nmol/L. Fifty (23.1%) patients had vitamin D deficiency, 120 (55.6%) had vitamin D insufficiency, while 46 (21.3%) had adequate vitamin D levels. There were statistically significant associations between vitamin D status and ethnic group, lupus nephritis and hypertension. No correlations were observed between vitamin D status with SLEDAI score (Pearson correlation coefficient -0.015, p=0.829) as well as SDI score (Pearson correlation coefficient -0.017, p=0.801).

CONCLUSION

SLE patients should be screened for vitamin D concentrations and their levels optimised.

Myrtus Polyphenols, from Antioxidants to Anti-Inflammatory Molecules: Exploring a Network Involving Cytochromes P450 and Vitamin D

Inflammatory response represents one of the main mechanisms of healing and tissue function restoration. On the other hand, chronic inflammation leads to excessive secretion of pro-inflammatory cytokines involved in the onset of several diseases. Oxidative stress condition may contribute in worsening inflammatory state fall, increasing reactive oxygen species (ROS) production and cytokines release. Polyphenols can counteract inflammation and oxidative stress, modulating the release of toxic molecules and interacting with physiological defenses, such as cytochromes p450 enzymes. In this paper, we aimed at evaluating the anti-inflammatory properties of different concentrations of Myrtus communis L. pulp and seeds extracts, derived from liquor industrial production, on human fibroblasts. We determined ROS production after oxidative stress induction by H₂O₂ treatment, and the gene expression of different proinflammatory cytokines. We also analyzed the expression of CYP3A4 and CYP27B1 genes, in order to evaluate the capability of Myrtus polyphenols to influence the metabolic regulation of other molecules, including drugs, ROS, and vitamin D. Our results showed that Myrtus extracts exert a synergic effect with vitamin D in reducing inflammation and ROS production, protecting cells from oxidative stress damages. Moreover, the extracts modulate CYPs expression, preventing chronic inflammation and suggesting their use in development of new therapeutic formulations.

Stabilization of Vitamin D in Pea Protein Isolate Nanoemulsions Increases Its Bioefficacy in Rats

Micronutrient delivery formulations based on nanoemulsions can enhance the absorption of nutrients and bioactives, and thus, are of great potential for food fortification and supplementation strategies. The aim was to evaluate the bioefficacy of vitamin D (VitD) encapsulated in nanoemulsions developed by sonication and pH-shifting of pea protein isolate (PPI) in restoring VitD status in VitD-deficient rats. Weaned male albino rats (n = 35) were fed either normal diet AIN-93G (VitD 1000 IU/kg) (control group; n = 7) or a VitD-deficient diet (<50 IU/kg) for six weeks (VitD-deficient group; n = 28). VitD-deficient rats were divided into four subgroups (n = 7/group). Nano-VitD and Oil-VitD groups received a dose of VitD (81 µg) dispersed in either PPI-nanoemulsions or in canola oil, respectively, every other day for one week. Their control groups, Nano-control and Oil-control, received the respective delivery vehicles without VitD. Serum 25-hydroxyvitamin D [25(OH)VitD], parathyroid hormone (PTH), Ca, P, and alkaline phosphatase (ALP) activity were measured. After one week of treatment, the VitD-deficient rats consuming Nano-VitD recovered from Vitamin D deficiency (VDD) as compared against baseline and had serum 25(OH)VitD higher than the Nano-control. Enhancement in VitD status was followed with expected changes in serum PTH, Ca, P, and ALP levels, as compared against the controls. Stabilization of VitD within PPI-based nanoemulsions enhances its absorption and restores its status and biomarkers of bone resorption in VitD-deficient rats.

Genomic Response to Vitamin D Supplementation in the Setting of a Randomized, Placebo-Controlled Trial

BACKGROUND

Vitamin D deficiency has been associated with multiple diseases, but the causal relevance and underlying processes are not fully understood. Elucidating the mechanisms of action of drug treatments in humans is challenging, but application of functional genomic approaches in randomized trials may afford an opportunity to systematically assess molecular responses.

METHODS

In the Biochemical Efficacy and Safety Trial of Vitamin D (BEST-D), a double-blind, placebo-controlled, dose-finding, randomized clinical trial, 305 community-dwelling individuals aged over 65 years were randomly allocated to treatment with vitamin D3 4000 IU, 2000 IU or placebo daily for 12 months. Genome-wide genotypes at baseline, and transcriptome and plasma levels of cytokines (IFN-γ, IL-10, IL-8, IL-6 and TNF-α) at baseline and after 12 months, were measured. The trial had >90% power to detect 1.2-fold changes in gene expression.

FINDINGS

Allocation to vitamin D for 12-months was associated with 2-fold higher plasma levels of 25-hydroxy-vitamin D (25[OH]D, 4000 IU regimen), but had no significant effect on whole-blood gene expression (FDR < 5%) or on plasma levels of cytokines compared with placebo. In pre-specified analysis, rs7041 (intron variant, GC) had a significant effect on circulating levels of 25(OH)D in the low dose, but not in the placebo or high dose vitamin D regimen. A gene expression quantitative trait locus analysis (eQTL) demonstrated evidence of 31,568 cis-eQTLs (unique SNP-probe pairs) among individuals at baseline and 34,254 after supplementation for 12 months (any dose). No significant associations involving vitamin D supplementation response eQTLs were found.

INTERPRETATION

We performed a comprehensive functional genomics and molecular analysis of vitamin D supplementation in a randomized, placebo-controlled trial. Although this study was limited to mostly Caucasian individuals aged over 65 years, the results differ from many previous studies and do not support a strong effect of vitamin D on long-term transcriptomic changes in blood or on plasma cytokine levels. The trial demonstrates the feasibility of applying functional genomic and genetic approaches in randomized trials to assess molecular and individual level responses.

KEY RESULT

Supplementation with high-dose vitamin D in older people for 12 months in a randomized, placebo-controlled trial had no significant effect on gene expression or on plasma concentrations of selected cytokines.

TRIAL REGISTRATION

SRCTN registry (Number 07034656) and the European Clinical Trials Database (EudraCT Number 2011-005763-24).

Baseline characteristics of participants in the VITamin D and OmegA-3 TriaL (VITAL): Effects on Bone Structure and Architecture

Vitamin D supplements are often used to benefit skeletal health, although data on effects of daily high-dose vitamin D alone on bone density and structure are lacking. The ongoing VITamin D and OmegA-3 TriaL (VITAL) is a double-blind, randomized, placebo-controlled trial testing effects of high-dose supplemental vitamin D3 (cholecalciferol; 2000 IU/day) and/or omega-3 fatty acids (FAs; 1 g/day) for the primary prevention of cancer and cardiovascular disease. The study has a mean treatment period of 5 years among 25,874 U.S. men ≥50 years and women ≥55 years old from all 50 states. The ancillary study, VITAL: Effects on Bone Structure and Architecture, is testing effects of vitamin D3 and/or omega-3 FAs on musculoskeletal outcomes and body composition in a subcohort of 771 participants. At in-person visits at the Harvard Catalyst Clinical and Translational Science Center (CTSC), participants completed bone density/architecture, body composition, and physical performance assessments at baseline and two-year follow-up. Baseline characteristics were evenly distributed among treatment groups, suggesting that any uninvestigated confounders will be evenly distributed; sex differences were also analyzed. Future analyses of the two-year follow-up visits will elucidate whether daily high-dose, supplemental vitamin D3 and/or omega-3 FAs improve musculoskeletal outcomes, helping to advance clinical and public health recommendations.

CLINICAL TRIAL REGISTRATION NUMBER

NCT01747447.

Gene Expression Pattern in Response to Cholecalciferol Supplementation Highlights Cubilin as a Major Protein of 25(OH)D Uptake in Adipocytes and Male Mice White Adipose Tissue

It is well established that the active form of vitamin D (i.e., 1,25-dihydroxyvitamin D [1,25(OH)2D]) regulates the expression of genes involved in its own metabolism and transport in the kidney and possibly in the liver. However, little is known about the transcriptional impact of cholecalciferol supplementation on white adipose tissue (WAT) and adipocytes, which are a major site of vitamin D and 25-hydroxyvitamin D [25(OH)D] storage in the organism. To fill this gap, we investigated the impact of cholecalciferol supplementation in WAT via a panel of genes coding for enzymes and proteins involved in vitamin D metabolism and uptake. Mice supplemented with cholecalciferol (15,000 IU/kg of body weight per day) for 4 days showed decreased messenger RNA (mRNA) levels of proteins involved in cholecalciferol metabolism (Cyp24a1, Cyp27a1) and decreased cubilin mRNA levels in WAT. These data were partly confirmed in 3T3-L1 adipocytes incubated with 1,25(OH)2D. The downregulation of cubilin mRNA observed in WAT and in 3T3-L1 was confirmed at the protein level in WAT and at the mRNA level in human primary adipocytes. Vitamin D receptor (VDR) agonist (EB1089) and RNA interference approaches demonstrated that VDR was involved in this regulation. Furthermore, chemical inhibitor and RNA inference analysis demonstrated that cubilin was involved in 25(OH)D uptake by adipocytes. This study established an overall snapshot of the genes regulated by cholecalciferol in mouse WAT and cell-autonomously in adipocytes. We highlighted that the regulation of cubilin expression was mediated by a VDR-dependent mechanism, and we demonstrated that cubilin was involved in 25(OH)D uptake by adipocytes.

Fish oil based vitamin D nanoencapsulation by ultrasonication and bioaccessibility analysis in simulated gastro-intestinal tract

Recently, nanoemulsions have been employed for different applications including food and drug industries for efficient nutrient delivery system. In this study, vitamin D (a lipophilic molecule) was encapsulated in fish oil for higher oral bioavailability. The oil-in-water nanoemulsion was formulated by ultrasonication technique with a droplet size range of 300-450nm and a shelf life of more than 90days. The influence of oil, water and surfactant concentration was investigated by phase diagram. The formulated nanoemulsion had encapsulation efficiency in the range of 95.7-98.2%. Further, nanoemulsion passed through simulated gastro-intestinal tract revealed an increased bioavailability than non-encapsulated vitamin. Thus, the formulation can be used as a drug delivery vehicle for various lipophilic compounds. Till date, no one have fabricated an efficient nano-vehicle for the delivery of vitamin D as well as analyzed the efficient delivery system in simulated GI-tract, this is first of its kind study in this regard. This can be scaled up further after analyzing the safety aspects.

A nonrandomized trial of vitamin D supplementation for Barrett's esophagus

Background

Vitamin D deficiency may increase esophageal cancer risk. Vitamin D affects genes regulating proliferation, apoptosis, and differentiation and induces the tumor suppressor 15-hydroxyprostaglandin dehydrogenase (PGDH) in other cancers. This nonrandomized interventional study assessed effects of vitamin D supplementation in Barrett’s esophagus (BE). We hypothesized that vitamin D supplementation may have beneficial effects on gene expression including 15-PGDH in BE.

Methods

BE subjects with low grade or no dysplasia received vitamin D₃ (cholecalciferol) 50,000 international units weekly plus a proton pump inhibitor for 12 weeks. Esophageal biopsies from normal plus metaplastic BE epithelium and blood samples were obtained before and after vitamin D supplementation. Serum 25-hydroxyvitamin D was measured to characterize vitamin D status. Esophageal gene expression was assessed using microarrays.

Results

18 study subjects were evaluated. The baseline mean serum 25-hydroxyvitamin D level was 27 ng/mL (normal ≥30 ng/mL). After vitamin D supplementation, 25-hydroxyvitamin D levels rose significantly (median increase of 31.6 ng/mL, p<0.001). There were no significant changes in gene expression from esophageal squamous or Barrett’s epithelium including 15-PGDH after supplementation.

Conclusion

BE subjects were vitamin D insufficient. Despite improved vitamin D status with supplementation, no significant alterations in gene expression profiles were noted. If vitamin D supplementation benefits BE, a longer duration or higher dose of supplementation may be needed.

Impaired Release of Vitamin D in Dysfunctional Adipose Tissue: New Cues on Vitamin D Supplementation in Obesity

CONTEXT

Vitamin D accumulates in adipose tissue (AT), and vitamin D deficiency is frequent in obesity.

OBJECTIVE

We hypothesize that trafficking of vitamin D is altered in dysfunctional AT.

DESIGN, PATIENTS, SETTINGS

Fifty-four normal-weight and 67 obese males were recruited in a prospective study and randomly assigned to supplementation with 50 µg/wk 25-hydroxyvitamin-D3 or 150 µg/wk vitamin D3 for 1 year, raising dosage by 50% if vitamin D sufficiency [serum 25-hydroxyvitamin-D3 >50 nmol/L], was not achieved at 6 months; 97 subjects completed the study.

METHODS

Vitamin D3 and 25-hydroxyvitamin-D3 were quantified by HPLC-MS in control and insulin-resistant (IR) 3T3-L1 cells and subcutaneous AT (SAT) from lean and obese subjects, incubated with or without adrenaline; expression of 25-hydroxylase (Cyp27a1), 1α-hydroxylase (Cyp27b1), and vitamin D receptor (Vdr) was analyzed by real-time polymerase chain reaction.

RESULTS

In IR adipocytes, uptake of D3 and 25-hydroxyvitamin-D3 was higher, but, after adrenaline stimulation, the decrement in D3 and 25-hydroxyvitamin-D3 was stronger in control cells, which also showed increased expression of Cyp27a1 and Cyp27b1 and higher levels of 25-hydroxyvitamin-D3. In SAT from obese subjects, adrenaline-induced release of D3 and 25-hydroxyvitamin-D3 was blunted; in both IR cells and obese SAT, protein expression of β2-adrenergic receptor was reduced. Supplementation with 25-hydroxyvitamin-D3 was more effective in achieving vitamin D sufficiency in obese, but not in normal weight subjects.

CONCLUSION

Dysfunctional AT shows a reduced catecholamine-induced release of D3 and 25-hydroxyvitamin-D3 and altered activity of vitamin D-metabolizing enzymes; for these reasons supplementation with 25-hydroxyvitamin-D3 is more effective in obese individuals.

Growth Hormone Favorably Affects Bone Turnover and Bone Mineral Density in Patients With Short Bowel Syndrome Undergoing Intestinal Rehabilitation

BACKGROUND

Patients with short bowel syndrome (SBS) have a high prevalence of metabolic bone disease due to nutrient malabsorption and potential effects of parenteral nutrition (PN). Human growth hormone (hGH) has been shown in some studies to have anabolic effects on bone, but hGH effects on bone in patients with SBS are unknown.

METHODS

Adults with PN-dependent SBS underwent a 7-day period of baseline studies while receiving usual oral diet and PN and then began receiving modified diets designed to improve nutrient absorption and daily oral calcium/vitamin D supplements (1500 mg elemental calcium and 600 IU vitamin D, respectively). Subjects were randomized to receive in a double-blind manner either subcutaneous (sc) saline placebo as the control or hGH (0.1 mg/kg/d for 3 weeks, then 0.1 mg/kg 3 days a week for 8 subsequent weeks). Open-label hGH was given from week 13 to week 24 in subjects who required PN after completion of the 12-week double-blind phase. Markers of bone turnover (serum osteocalcin and urinary N-telopeptide [NTX]), vitamin D nutriture (serum calcium, 25-hydroxyvitamin D [25-OH D] and parathyroid hormone [PTH] concentrations), and intestinal calcium absorption were measured at baseline and at weeks 4 and 12. Dual x-ray absorptiometry (DXA) of the hip and spine was performed to determine bone mineral density (BMD) at baseline and weeks 12 and 24.

RESULTS

The majority of subjects in each group exhibited evidence of vitamin D deficiency at baseline (25-OH D levels<30 ng/mL; 78% and 79% of control and hGH-treated subjects, respectively). Subjects treated with hGH demonstrated a significant increase from baseline in serum osteocalcin levels at 12 weeks (+62%; p<.05). The levels of NTX were increased over time in the hGH-treated group; however, this did not reach statistical significance. Both NTX and osteocalcin remained unchanged in control subjects. BMD of the spine and total hip was unchanged in subjects treated with placebo or hGH at 24 weeks. However, femoral neck BMD was slightly but significantly decreased in the placebo group at this time point but remained unchanged from baseline in the hGH-treated subjects.

CONCLUSIONS

hGH therapy significantly increased markers of bone turnover during the initial 3 months of therapy and stabilized femoral neck bone mass over a 6-month period in patients with severe SBS undergoing intestinal rehabilitation.

Prevention of preeclampsia

Preeclampsia is a common complication of pregnancy that is associated with an increased risk of maternal and neonatal morbidity and mortality. Currently, delivery is the only cure for preeclampsia; therefore, effective prevention and treatment options for this condition are sorely needed. In the current issue of the JCI, Mirzakhani et al. report the findings of the Vitamin D Antenatal Asthma Reduction Trial (VDAART), a well-conducted large, randomized, double-blind, placebo-controlled trial of vitamin D supplementation for the prevention of preeclampsia. Though vitamin D supplementation had no effect on the risk of preeclampsia, reduced maternal serum vitamin D levels did correlate with preeclampsia risk. Mirzakhani and colleagues identified a number of gene pathways that are differentially regulated among women with low serum vitamin D levels who develop preeclampsia. These results indicate that further research on the role of vitamin D in preeclampsia is warranted.

Early pregnancy vitamin D status and risk of preeclampsia

BACKGROUND

Low vitamin D status in pregnancy was proposed as a risk factor of preeclampsia.

METHODS

We assessed the effect of vitamin D supplementation (4,400 vs. 400 IU/day), initiated early in pregnancy (10-18 weeks), on the development of preeclampsia. The effects of serum vitamin D (25-hydroxyvitamin D [25OHD]) levels on preeclampsia incidence at trial entry and in the third trimester (32-38 weeks) were studied. We also conducted a nested case-control study of 157 women to investigate peripheral blood vitamin D-associated gene expression profiles at 10 to 18 weeks in 47 participants who developed preeclampsia.

RESULTS

Of 881 women randomized, outcome data were available for 816, with 67 (8.2%) developing preeclampsia. There was no significant difference between treatment (N = 408) or control (N = 408) groups in the incidence of preeclampsia (8.08% vs. 8.33%, respectively; relative risk: 0.97; 95% CI, 0.61-1.53). However, in a cohort analysis and after adjustment for confounders, a significant effect of sufficient vitamin D status (25OHD ≥30 ng/ml) was observed in both early and late pregnancy compared with insufficient levels (25OHD <30 ng/ml) (adjusted odds ratio, 0.28; 95% CI, 0.10-0.96). Differential expression of 348 vitamin D-associated genes (158 upregulated) was found in peripheral blood of women who developed preeclampsia (FDR <0.05 in the Vitamin D Antenatal Asthma Reduction Trial [VDAART]; P < 0.05 in a replication cohort). Functional enrichment and network analyses of this vitamin D-associated gene set suggests several highly functional modules related to systematic inflammatory and immune responses, including some nodes with a high degree of connectivity.

CONCLUSIONS

Vitamin D supplementation initiated in weeks 10-18 of pregnancy did not reduce preeclampsia incidence in the intention-to-treat paradigm. However, vitamin D levels of 30 ng/ml or higher at trial entry and in late pregnancy were associated with a lower risk of preeclampsia. Differentially expressed vitamin D-associated transcriptomes implicated the emergence of an early pregnancy, distinctive immune response in women who went on to develop preeclampsia.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00920621.

FUNDING

Quebec Breast Cancer Foundation and Genome Canada Innovation Network. This trial was funded by the National Heart, Lung, and Blood Institute. For details see Acknowledgments.

A Retrospective Study in Adults with Metabolic Syndrome: Diabetic Risk Factor Response to Daily Consumption of Agaricus bisporus (White Button Mushrooms)

Adults with metabolic syndrome from different race/ethnicities are often predisposed to developing type 2 diabetes (T2D); however, growing evidence suggests that healthy diets and lifestyle choices can significantly slow or prevent progression to T2D. This poorly understood relationship to healthy dietary patterns and prevention of T2D motivated us to conduct a retrospective analysis to determine the potential impact of a minor dietary lifestyle change (daily mushroom consumption) on known T2D risk factors in racially diverse adults with confirmed features of the metabolic syndrome. Retrospectively, we studied 37 subjects who had participated in a dietary intervention focused on vitamin D bioavailability from white button mushrooms (WBM). All 37 had previously completed a 16-week study where they consumed 100 g of WBM daily and were then followed-up for one month during which no mushrooms were consumed. We analyzed differences in serum risk factors from baseline to 16-week, and from baseline to one-month follow-up. Measurement of serum diabetic risk factors included inflammatory and oxidative stress markers and the antioxidant component naturally rich in mushrooms, ergothioneine. Significant beneficial health effects were observed at 16-week with the doubling of ergothioneine from baseline, increases in the antioxidant marker ORAC (oxygen radical absorption capacity) and anti-inflammatory hormone, adiponectin and significant decreases in serum oxidative stress inducing factors, carboxymethyllysine (CML) and methylglyoxal (MG), but no change in the lipid oxidative stress marker 8-isoprostane, leptin or measures of insulin resistance or glucose metabolism. We conclude that WBM contain a variety of compounds with potential anti-inflammatory and antioxidant health benefits that can occur with frequent consumption over time in adults predisposed to T2D. Well-controlled studies are needed to confirm these findings and identify the specific mushroom components beneficial to health.

Impact of a cholesterol membrane transporter's inhibition on vitamin D absorption: A double-blind randomized placebo-controlled study

Oral supplements are important to prevent and treat vitamin D deficiency. Despite the growing number of prescriptions, vitamin D's absorptive mechanisms are not clearly elucidated. By evaluating the effect of ezetimibe on vitamin D absorption, we aim to determine if the cholesterol transporter Niemann-Pick C1-Like 1 transporter contributes to it. This randomized, double-blind, placebo-controlled trial (ClinicalTrials.govNCT02234544) was developed in a South Brazilian University Hospital. Fifty-one medical students were randomized to ezetimibe 10mg/day or placebo for 5 days. On the fifth and 19th days, blood samples for 25-hydroxycholecalciferol (25OHD), parathyroid hormone (PTH), calcium, and albumin were collected. After the first blood sample collection, all participants received a single oral 50,000 IU cholecalciferol dose during a 15 g-fat meal. Serum 25OHD levels were measured by the immunoassay Diasorin Liaison®. Measurements were compared in a general linear model adjusted for multiple comparisons by the Bonferroni test. Before cholecalciferol administration, 25OHD was <30 ng/mL and <20 ng/mL, respectively, in all and in 82.3% of the participants. Fourteen days after a single 50,000 IU oral dose of cholecalciferol, mean (SD) changes in serum 25OHD were similar in both groups, after adjustment to BMI and 25OHD levels before cholecalciferol administration (p=0.26): 8.7 (3.7) ng/mL in the ezetimibe group, versus 10.0 (3.8) ng/mL in the placebo group. Mean serum 25OHD, PTH, calcium and albumin levels remained similar in both groups. We conclude that ezetimibe had no effect on the mean change in serum 25OHD after a single oral dose of cholecalciferol, in these healthy and young adults.

Intestinal Calcium Absorption Decreases Dramatically After Gastric Bypass Surgery Despite Optimization of Vitamin D Status

Roux-en-Y gastric bypass (RYGB) surgery has negative effects on bone, mediated in part by effects on nutrient absorption. Not only can RYGB result in vitamin D malabsorption, but the bypassed duodenum and proximal jejunum are also the predominant sites of active, transcellular, 1,25(OH)2 D-mediated calcium (Ca) uptake. However, Ca absorption occurs throughout the intestine, and those who undergo RYGB might maintain sufficient Ca absorption, particularly if vitamin D status and Ca intake are robust. We determined the effects of RYGB on intestinal fractional Ca absorption (FCA) while maintaining ample 25OHD levels (goal ≥30 ng/mL) and Ca intake (1200 mg daily) in a prospective cohort of 33 obese adults (BMI 44.7 ± 7.4 kg/m(2)). FCA was measured preoperatively and 6 months postoperatively with a dual stable isotope method. Other measures included calciotropic hormones, bone turnover markers, and BMD by DXA and QCT. Mean 6-month weight loss was 32.5 ± 8.4 kg (25.8% ± 5.2% of preoperative weight). FCA decreased from 32.7% ± 14.0% preoperatively to 6.9% ± 3.8% postoperatively (p < 0.0001), despite median (interquartile range) 25OHD levels of 41.0 (33.1 to 48.5) and 36.5 (28.8 to 40.4) ng/mL, respectively. Consistent with the FCA decline, 24-hour urinary Ca decreased, PTH increased, and 1,25(OH)2 D increased (p ≤ 0.02). Bone turnover markers increased markedly, areal BMD decreased at the proximal femur, and volumetric BMD decreased at the spine (p < 0.001). Those with lower postoperative FCA had greater increases in serum CTx (ρ = -0.43, p = 0.01). Declines in FCA and BMD were not correlated over the 6 months. In conclusion, FCA decreased dramatically after RYGB, even with most 25OHD levels ≥30 ng/mL and with recommended Ca intake. RYGB patients may need high Ca intake to prevent perturbations in Ca homeostasis, although the approach to Ca supplementation needs further study. Decline in FCA could contribute to the decline in BMD after RYGB, and strategies to avoid long-term skeletal consequences should be investigated.

Effect of Vitamin D Supplementation on Blood Pressure: A Systematic Review and Meta-analysis Incorporating Individual Patient Data

IMPORTANCE

Low levels of vitamin D are associated with elevated blood pressure (BP) and future cardiovascular events. Whether vitamin D supplementation reduces BP and which patient characteristics predict a response remain unclear.

OBJECTIVE

To systematically review whether supplementation with vitamin D or its analogues reduce BP.

DATA SOURCES

We searched MEDLINE, CINAHL, EMBASE, Cochrane Central Register of Controlled Trials, and http://www.ClinicalTrials.com augmented by a hand search of references from the included articles and previous reviews. Google was searched for gray literature (ie, material not published in recognized scientific journals). No language restrictions were applied. The search period spanned January 1, 1966, through March 31, 2014.

STUDY SELECTION

We included randomized placebo-controlled clinical trials that used vitamin D supplementation for a minimum of 4 weeks for any indication and reported BP data. Studies were included if they used active or inactive forms of vitamin D or vitamin D analogues. Cointerventions were permitted if identical in all treatment arms.

DATA EXTRACTION AND SYNTHESIS

We extracted data on baseline demographics, 25-hydroxyvitamin D levels, systolic and diastolic BP (SBP and DBP), and change in BP from baseline to the final follow-up. Individual patient data on age, sex, medication use, diabetes mellitus, baseline and follow-up BP, and 25-hydroxyvitamin D levels were requested from the authors of the included studies. For trial-level data, between-group differences in BP change were combined in a random-effects model. For individual patient data, between-group differences in BP at the final follow up, adjusted for baseline BP, were calculated before combining in a random-effects model.

MAIN OUTCOMES AND MEASURES

Difference in SBP and DBP measured in an office setting.

RESULTS

We included 46 trials (4541 participants) in the trial-level meta-analysis. Individual patient data were obtained for 27 trials (3092 participants). At the trial level, no effect of vitamin D supplementation was seen on SBP (effect size, 0.0 [95% CI, -0.8 to 0.8] mm Hg; P=.97; I2=21%) or DBP (effect size, -0.1 [95% CI, -0.6 to 0.5] mm Hg; P=.84; I2=20%). Similar results were found analyzing individual patient data for SBP (effect size, -0.5 [95% CI, -1.3 to 0.4] mm Hg; P=.27; I2=0%) and DBP (effect size, 0.2 [95% CI, -0.3 to 0.7] mm Hg; P=.38; I2=0%). Subgroup analysis did not reveal any baseline factor predictive of a better response to therapy.

CONCLUSIONS AND RELEVANCE

Vitamin D supplementation is ineffective as an agent for lowering BP and thus should not be used as an antihypertensive agent.

The vitamin D, ionised calcium and parathyroid hormone axis of cerebral capillary function: therapeutic considerations for vascular-based neurodegenerative disorders

Blood-brain barrier dysfunction characterised by brain parenchymal extravasation of plasma proteins may contribute to risk of neurodegenerative disorders, however the mechanisms for increased capillary permeability are not understood. Increasing evidence suggests vitamin D confers central nervous system benefits and there is increasing demand for vitamin D supplementation. Vitamin D may influence the CNS via modulation of capillary function, however such effects may be indirect as it has a central role in maintaining calcium homeostasis, in concert with calcium regulatory hormones. This study utilised an integrated approach and investigated the effects of vitamin D supplementation, parathyroid tissue ablation (PTX), or exogenous infusion of parathyroid hormone (PTH) on cerebral capillary integrity. Parenchymal extravasation of immunoglobulin G (IgG) was used as a marker of cerebral capillary permeability. In C57BL/6J mice and Sprague Dawley rats, dietary vitamin D was associated with exaggerated abundance of IgG within cerebral cortex (CTX) and hippocampal formation (HPF). Vitamin D was also associated with increased plasma ionised calcium (iCa) and decreased PTH. A response to dose was suggested and parenchymal effects persisted for up to 24 weeks. Ablation of parathyroid glands increased CTX- and HPF-IgG abundance concomitant with a reduction in plasma iCa. With the provision of PTH, iCa levels increased, however the PTH treated animals did not show increased cerebral permeability. Vitamin D supplemented groups and rats with PTH-tissue ablation showed modestly increased parenchymal abundance of glial-fibrillary acidic protein (GFAP), a marker of astroglial activation. PTH infusion attenuated GFAP abundance. The findings suggest that vitamin D can compromise capillary integrity via a mechanism that is independent of calcium homeostasis. The effects of exogenous vitamin D supplementation on capillary function and in the context of prevention of vascular neurodegenerative conditions should be considered in the context of synergistic effects with calcium modulating hormones.

Prevalence and correction of severe hypovitaminosis D in patients over 50 years with a low-energy fracture

PURPOSE/INTRODUCTION

To examine the increase in serum 25(OH) vitamin D levels after supplementation with 800 IU/day of vitamin D in patients with low vitamin D levels and which factors affected the increase in vitamin D levels.

METHODS

The study included patients > 50 years with a low-energy fracture and a vitamin D level < 30 nmol/l. This was a retrospective study and was carried out at a large non-teaching hospital in the Netherlands.

RESULTS

82 patients were included, mean basal 25(OH) vitamin D level was 21.2 nmol/l. After a mean of 9.8 weeks, the mean increase in vitamin D was 48.5 nmol/l. Only 45.1% reached the target level of > 50 nmol/l. The increase was correlated with the basal level of vitamin D (p < 0.05), and the time interval between the two vitamin D measurements (p < 0.05) and was inversely related to body weight (p < 0.05), but was not related to age, gender or renal function.

CONCLUSIONS

We found that the generally recommended dosage of 800 IU of vitamin D per day resulted in suboptimal serum levels after ten weeks of treatment in more than half of the patients. The increase in vitamin D levels was higher in patients with low body weight and in patients with very low basal vitamin D levels. These data suggest that these patients should initially be treated with higher dosages of vitamin D. If not possible, vitamin D measurements should be performed after at least six months of supplementation with dosage adjustment.

Associations between vascular health indices and serum total, free and bioavailable 25-hydroxyvitamin D in adolescents

Objective

The role of vitamin D in cardiovascular health remains debated as results have been inconsistent. Previous studies have not considered the bioavailability of 25-hydroxy vitamin D [25(OH)D]. Objectives of our study were to investigate the association between serum concentrations of total, free and bioavailable 25(OH)D and independent predictors of cardiovascular risk such as flow mediated dilatation (FMD) and augmentation index (AIx).

Design

This cross-sectional study included 47 post-menarchal, adolescent females [31 African American (AA) and 16 European American (EA)].

Methods

AIx was standardized to a heart rate of 75 beats/min (AIx75). Free and bioavailable 25(OH)D concentrations were calculated from standard formulas.

Results and Conclusions

Mean age of the participants was 15.8±1.4 years and mean body mass index was 23.1±4.0 kg/m². Serum total 25(OH)D was not associated with FMD, but was positively associated with AIx75 in the adjusted model (rho = 0.4, P = 0.03). AIx75 was positively associated with bioavailable 25(OH)D (rho = 0.4, P = 0.004) and free 25(OH)D (rho = 0.4, P = 0.009) and the associations persisted after adjusting for covariates. In race-specific analyses, total, free and bioavailable 25(OH)D were strongly positively associated with AIx75 in AA (rho = 0.5, 0.4, 0.4, respectively), which persisted even after adjusting for covariates. Whereas in EA there was an inverse association between total 25(OH)D and AIx75 in EA (rho = −0.6), which attenuated after adjusting for covariates.

Conclusion

Circulating total, free and bioavailable 25(OH)D were associated with arterial stiffness in adolescent girls, and these associations were race dependent. Notwithstanding, the implications of associations between vascular function indices and 25(OH)D remains unclear.

A randomised controlled trial of high dose vitamin D in recent-onset type 2 diabetes

AIMS

Vitamin D insufficiency has been associated with impaired pancreatic beta-cell function. We aimed to determine if high dose oral vitamin D3 (D) improves beta-cell function and glycaemia in type 2 diabetes.

METHODS

Fifty adults with type 2 diabetes diagnosed less than 12 months, with normal baseline serum 25-OH D (25D), were randomised to 6000 IU D (n=26) or placebo (n=24) daily for 6 months. Beta-cell function was measured by glucagon-stimulated serum C-peptide (delta C-peptide [DCP], nmol/l). Secondary outcome measures were fasting plasma glucose (FPG), post-prandial blood glucose (PPG), HbA1c and insulin resistance (HOMA-IR).

RESULTS

In the D group, median serum 25D (nmol/l) increased from 59 to 150 (3 months) and 128 (6 months) and median serum 1,25D (pmol/l) from 135 to 200 and 190. After 3 months, change in DCP from baseline in D (+0.04) and placebo (-0.08) was not different (P=0.112). However, change in FPG (mmol/l) was significantly lower in D (-0.40) compared to placebo (+0.1) (P=0.007), as was the change in PPG in D (-0.30) compared to placebo (+0.8) (P=0.005). Change in HbA1c (%) between D (-0.20) and placebo (-0.10) was not different (P=0.459). At 6 months, changes from baseline in DCP, FPG, PPG and HbA1c were not different between groups.

CONCLUSION

Oral D3 supplementation in type 2 diabetes was associated with transient improvement in glycaemia, but without a measurable change in beta-cell function this effect is unlikely to be biologically significant. High dose D3 therefore appears to offer little or no therapeutic benefit in type 2 diabetes.

Human pharmacokinetic profile of 1,25-dihydroxyvitamin D3-glycoside of herbal origin

A natural form of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), the active metabolite of vitamin D, was identified in glycosylated form in Solanum glaucophyllum (SG). Solbone P, an extract of SG with high and homogenous content of glycosylated 1,25(OH)2D3, was chemically characterized and produced under GMP conditions. Three different doses of glycosylated 1,25(OH)2D3 were given as single oral dose to 16 healthy volunteers in a first-in-man trial. The oral pharmacokinetic properties of 1,25(OH)2D3 of SG origin were established and the subjects were monitored until day 28 for safety reasons. This included regular monitoring of vital signs, electrocardiogram (ECG) data, calcium, phosphate and creatinine values. Subjects were exposed to up to the equivalent of a 40-fold level of the recommended human daily dose for synthetic 1,25(OH)2D3 (0.5μg/subject/day) without experiencing any untoward effects. When compared with the historically established pharmacokinetics profile of synthetic 1,25(OH)2D3, glycosylated 1,25(OH)2D3 of herbal origin exhibited delayed absorption characteristics. The phenomenon is species independent, as similar pharmacokinetic patterns were observed in rats and chickens. This modified release pattern may be attributed to the glycosylation of herbal 1,25(OH)2D3 because de-glycosylation by ubiquitous intestinal enzymes prior to intestinal uptake of the unmodified 1,25(OH)2D3 is the rate-limiting step. The major relevance of this finding is that the human pharmacokinetic profile of glycosylated 1,25(OH)2D3 of herbal origin is reminiscent of a delayed release formulation of free 1,25(OH)2D3, resulting in a wider therapeutic window, a potentially longer therapeutic effectiveness, and thus, a better pharmacologic tolerance. This article is part of a Special Issue entitled '16th Vitamin D Workshop'.

Vitamin D deficiency: a simple algorithm employing weekly administration of 50,000 IU of vitamin D

OBJECTIVE

Vitamin D deficiency affects parathyroid hormone levels and is endemic in the American population due to diet and lifestyle. The aim of this study was to evaluate a treatment algorithm using weekly doses of 50,000 IU of Vitamin D2 for thyroid and parathyroid surgery patients.

STUDY DESIGN

Prospective, non-randomized.

SETTING

University health sciences center.

SUBJECTS AND METHODS

Patients at a thyroid center being treated for benign and malignant thyroid diseases or parathyroid disease. Subjects with total vitamin D levels less than 30 ng/dl were prospectively treated with weekly doses of 50,000 IU of vitamin D2 (D2) for durations dependent upon initial vitamin D (25-hydroxyvitamin D) levels. Vitamin D levels were measured after the treatment intervals and change in levels from baseline was determined.

RESULTS

Subjects receiving 8 weeks of therapy demonstrated an average increase in vitamin D level of 13.4 ng/ml, 10 weeks of therapy showed an increase of 16.35 ng/ml, and 12 weeks showed an average increase of 21.6 ng/ml. The treatment groups had success rates of 82%, 75%, and 71% after 8, 10, and 12 weeks of therapy respectively. When only compliant patients were evaluated (defined as greater than 3-ng/ml increase after therapy), the success rates after 8, 10, and 12 weeks increased to 95%, 79%, and 71% respectively.

CONCLUSIONS

A simple algorithm using 50,000 IU of vitamin D2 corrects its deficiency in the majority of subjects treated. This is a simple method of treatment for thyroid and parathyroid patients who are vitamin D deficient. Thyroid and parathyroid conditions are frequently treated by otolaryngologists and vitamin D deficiency can complicate their diagnosis and/or management.

Multifunctional and potent roles of the 3-hydroxypropoxy group provide eldecalcitol's benefit in osteoporosis treatment

Eldecalcitol (1α,25-dihydroxy-2β-(3-hydroxypropoxy)vitamin D3, [developing code: ED-71]), a new osteoporosis treatment drug that was recently approved in Japan, is a best-in-class drug in the class of calcitriol (1α,25-dihydroxyvitamin D3) and its prodrug alfacalcidol (1α-hydroxyvitamin D3), which have been used to treat osteoporosis for 30 years. In a comparative Phase III clinical study with alfacalcidol in osteoporosis patients, eldecalcitol demonstrated superior efficacy in the endpoints of increment of bone mineral density and reduction of bone fracture with equivalent safety to alfacalcidol. Eldecalcitol was discovered by searching synthetic analogs of calcitriol and alfacalcidol, and its main structural characteristic is having the 3-hydroxypropoxy group at the 2β-position. This review discusses why introducing the group leads to excellent efficacy and safety in osteoporosis treatment and elucidates the functional roles of the 3-hydroxypropoxy group. Briefly, the functional roles of the group are, first, realizing the metabolism switching in which eldecalcitol shows resistance to CYP24A1 and is metabolized in the liver; second, increasing the affinity to the serum carrier protein and prolonging the half-life to 53h; and third, stabilizing the eldecalcitol-receptor complex. Taken together, these functional roles of the 3-hydroxypropoxy group are beneficial in osteoporosis treatment. This review attempts to give a detailed account of the mode of action of eldecalcitol by clarifying these multifunctional roles of the 3-hydroxypropoxy group from the medicinal chemist's perspective.

Vitamin D-binding protein and vitamin D status of black Americans and white Americans

BACKGROUND

Low levels of total 25-hydroxyvitamin D are common among black Americans. Vitamin D-binding protein has not been considered in the assessment of vitamin D deficiency.

METHODS

In the Healthy Aging in Neighborhoods of Diversity across the Life Span cohort of blacks and whites (2085 participants), we measured levels of total 25-hydroxyvitamin D, vitamin D-binding protein, and parathyroid hormone as well as bone mineral density (BMD). We genotyped study participants for two common polymorphisms in the vitamin D-binding protein gene (rs7041 and rs4588). We estimated levels of bioavailable 25-hydroxyvitamin D in homozygous participants.

RESULTS

Mean (±SE) levels of both total 25-hydroxyvitamin D and vitamin D-binding protein were lower in blacks than in whites (total 25-hydroxyvitamin D, 15.6±0.2 ng per milliliter vs. 25.8±0.4 ng per milliliter, P<0.001; vitamin D-binding protein, 168±3 μg per milliliter vs. 337±5 μg per milliliter, P<0.001). Genetic polymorphisms independently appeared to explain 79.4% and 9.9% of the variation in levels of vitamin D-binding protein and total 25-hydroxyvitamin D, respectively. BMD was higher in blacks than in whites (1.05±0.01 g per square centimeter vs. 0.94±0.01 g per square centimeter, P<0.001). Levels of parathyroid hormone increased with decreasing levels of total or bioavailable 25-hydroxyvitamin D (P<0.001 for both relationships), yet within each quintile of parathyroid hormone concentration, blacks had significantly lower levels of total 25-hydroxyvitamin D than whites. Among homozygous participants, blacks and whites had similar levels of bioavailable 25-hydroxyvitamin D overall (2.9±0.1 ng per milliliter and 3.1±0.1 ng per milliliter, respectively; P=0.71) and within quintiles of parathyroid hormone concentration.

CONCLUSIONS

Community-dwelling black Americans, as compared with whites, had low levels of total 25-hydroxyvitamin D and vitamin D-binding protein, resulting in similar concentrations of estimated bioavailable 25-hydroxyvitamin D. Racial differences in the prevalence of common genetic polymorphisms provide a likely explanation for this observation. (Funded by the National Institute on Aging and others.).

Clinical controversies in vitamin D: 25(OH)D measurement, target concentration, and supplementation

Despite a plethora of recent research and systematic reviews of available data, controversy continues to surround the definition of optimal vitamin D status, the daily intake needed, and the potential adverse health consequences of "insufficiency." Efforts to standardize vitamin D measurement and improve understanding of the physiologic consequences of other vitamin D metabolites such as 3-epi and 24,25(OH)2D (and potentially other vitamin D compounds) are needed. Currently, measurement of circulating 25(OH)D is accepted as the approach to define an individual's vitamin D status. However, existing 25(OH)D assays may include other vitamin D metabolites such as the 3-epimer of 25(OH)D and 24,25(OH)2D. It seems unlikely that the controversy will soon be resolved.

L-arginine and vitamin D adjunctive therapies in pulmonary tuberculosis: a randomised, double-blind, placebo-controlled trial

BACKGROUND

Vitamin D (vitD) and L-arginine have important antimycobacterial effects in humans. Adjunctive therapy with these agents has the potential to improve outcomes in active tuberculosis (TB).

METHODS

In a 4-arm randomised, double-blind, placebo-controlled factorial trial in adults with smear-positive pulmonary tuberculosis (PTB) in Timika, Indonesia, we tested the effect of oral adjunctive vitD 50,000 IU 4-weekly or matching placebo, and L-arginine 6.0 g daily or matching placebo, for 8 weeks, on proportions of participants with negative 4-week sputum culture, and on an 8-week clinical score (weight, FEV1, cough, sputum, haemoptysis). All participants with available endpoints were included in analyses according to the study arm to which they were originally assigned. Adults with new smear-positive PTB were eligible. The trial was registered at ClinicalTrials.gov NCT00677339.

RESULTS

200 participants were enrolled, less than the intended sample size: 50 received L-arginine + active vitD, 49 received L-arginine + placebo vit D, 51 received placebo L-arginine + active vitD and 50 received placebo L-arginine + placebo vitD. According to the factorial model, 99 people received arginine, 101 placebo arginine, 101 vitamin D, 99 placebo vitamin D. Results for the primary endpoints were available in 155 (4-week culture) and 167 (clinical score) participants. Sputum culture conversion was achieved by week 4 in 48/76 (63%) participants in the active L-arginine versus 48/79 (61%) in placebo L-arginine arms (risk difference -3%, 95% CI -19 to 13%), and in 44/75 (59%) in the active vitD versus 52/80 (65%) in the placebo vitD arms (risk difference 7%, 95% CI -9 to 22%). The mean clinical outcome score also did not differ between study arms. There were no effects of the interventions on adverse event rates including hypercalcaemia, or other secondary outcomes.

CONCLUSION

Neither vitD nor L-arginine supplementation, at the doses administered and with the power attained, affected TB outcomes.

REGISTRY

ClinicalTrials.gov. Registry number: NCT00677339.

The role of the serum vitamin D binding protein in the actions of the vitamin D analog eldecalcitol (ED-71) on bone and mineral metabolism

The vitamin D analog ED-71 (eldecalcitol) has been shown to be superior to calcitriol and its precursor alfacalcidol in maintaining or increasing bone mass in women and animal models with osteoporosis. The mechanism for the greater effectiveness of ED-71 is unknown. In the present study, we tested the hypothesis that the higher activity of ED-71 is due to its higher affinity for the serum vitamin D binding protein (DBP) by comparing the activities of orally administered ED-71, calcitriol and 22-oxacalcitriol (OCT) in wild type (WT) and DBP-ablated (DBPko) mice. In 8-week-old male WT mice, the effects of the analogs on serum and urinary calcium and phosphate were ED-71 > calcitriol > OCT. The results in DBPko mice were identical to those of the WT mice for all parameters tested. In ovariectomized mice, ED-71 was more effective than calcitriol in increasing bone mineral density, but again, there were no differences in the responses of the WT versus DBPko OVX mice. This lack of an effect of DBP ablation on the activities of oral ED-71 occurred despite the finding that peak circulating levels of ED-71 were 100 times lower and disappeared quickly in the DBPko mice while the peak levels at 1 h in WT mice were maintained for at least 24 h. These findings indicate that although DBP has a major influence on circulating levels of vitamin D compounds, it is not responsible for the greater efficacy of ED-71 on bone and mineral metabolism.

Interplay between vitamin D and the drug metabolizing enzyme CYP3A4

Cytochrome P450 3A4 (CYP3A4) is a multifunctional enzyme involved in both xenobiotic and endobiotic metabolism. This review focuses on two aspects: regulation of CYP3A4 expression by vitamin D and metabolism of vitamin D by CYP3A4. Enterohepatic circulation of vitamin D metabolites and their conjugates will be also discussed. The interplay between vitamin D and CYP3A4 provides new insights into our understanding of how enzyme induction can contribute to vitamin D deficiency. This article is part of a Special Issue entitled 'Vitamin D Workshop'.

Whole-body and microscopic autoradiography to determine tissue distribution of biopharmaceuticals -- target discoveries with receptor micro-autoradiography engendered new concepts and therapies for vitamin D

Information about the distribution of biopharmaceuticals is basic for understanding their actions. Tissue and cellular localization is a key to function. Autoradiography with radiolabeled compounds has provided valuable information with both low resolution whole-body macro-autoradiography and high resolution microscopic autoradiography (micro-autoradiography). Whole-body macro-autoradiography is a uniform and expedient single method approach, providing convenient dose- and time-related overviews with data similar to those obtained with conventional bioassays - and therefore widely used. However, whole-body macro-autoradiography, like common bioassays, has limitations. High specificity-low capacity sites of binding and deposition frequently remain unrecognized. Lack of cellular resolution can cause false negatives and provide misleading results (e.g., false blood-brain barrier). For micro-autoradiography, different methods are advertised in the literature. Most of them are, however, unsuited for drug localization because of inadequate resolution and frequent artifacts. Most drugs interact with their receptors non-covalently by weak electrostatic forces. Therefore, translocation and loss can occur during tissue preparation. This has complicated the use of micro-autoradiography. Receptor micro-autoradiography has overcome these complications and is a method of choice. It has been validated through several diffusible compounds with known localization, extensively applied. It has contributed numerous discoveries, followed by new concepts and therapies. Pictorial evidence in this review indicates that cellular information is essential, a 'sine qua non' for meaningful drug distribution studies. High resolution cellular microscopic information obtained from autoradiography requires tissue dissection and the necessary precautions for preserving pristine in vivo drug deposition. Receptor micro-autoradiography fulfils these requirements. It reveals crucial information at the subcellular level that cannot currently be obtained with any other type of autoradiography or spectrometric imaging.

Impact of maternal vitamin D status during pregnancy on neonatal vitamin D status

Maternal vitamin D deficiency is not uncommon. The lack of vitamin D during pregnancy may result in poor fetal growth and altered neonatal development that may persist into later life. Recognition of risk factors and early detection of vitamin D deficiency during pregnancy are important in order to prevent neonatal vitamin D deficiency and related complications. The aim of the current study was to assess the effect of maternal vitamin D status on the neonatal vitamin D stores. A total of 92 pregnant women at the end of the 3rd trimester and their newborns were recruited from Zagazig University Maternity and Children's Hospital, Egypt during the year 2011. Maternal and cord blood samples were taken at the beginning of the third trimester for determination of serum levels of circulating 25-hydroxyvitamin D3 (25(OH) D3) concentration, serum calcium (Ca++), phosphorus (PO4), and alkaline phosphatase (ALP). Compared with pregnant women with adequate vitamin D levels, women deficient in vitamin D had infants with vitamin D deficiency (X±SD 33.44±18.33 nmol/L vs. 55.39±17.37 nmol/L, p=0.01). Maternal and neonatal serum 25(OH)D3 levels showed a positive correlation with serum Ca++ and negative correlation with serum PO4 and ALP. Neonatal 25(OH) D3 was related to maternal third trimester levels (r=0.89, p=0.01). The newborn serum 25(OH)D3 concentrations are reliant on maternal vitamin D status, and the poor maternal vitamin D status may adversely affect neonatal vitamin D status and consequently Ca++ homeostasis.

Presence of valvular calcification predicts the response to cinacalcet: data from the ADVANCE study

BACKGROUND AND AIM OF THE STUDY

Cardiac valve calcification (CVC) and coronary artery calcification (CAC) appear to be linked pathogenetically, and both are associated with a poor prognosis among patients with chronic kidney disease on dialysis (CKD-5D). Little is known, however, about factors that affect the progression of CVC and CAC.

METHODS

A post-hoc analysis was performed of the ADVANCE study to assess whether patients with CVC are more prone to CAC progression, and whether CVC predicts the response to different treatments for secondary hyperparathyroidism.

RESULTS

Subjects were randomized to treatment with either cinacalcet and low doses of vitamin D analogs or larger, varying doses of vitamin D. Among 235 subjects, aortic valve or mitral valve calcification was detected in 108 (46%) and 118 (50%), respectively; 69 subjects (29%) had calcification of both valves. CVC was associated both with baseline CAC and CAC progression (p < 0.05). Subjects with aortic valve calcification who were treated with cinacalcet and low doses of vitamin D experienced less progression of CAC than subjects given larger, varying doses of vitamin D (adjusted OR: 0.26; 95% CI: 0.10, 0.64). This effect was greater in subjects with larger CAC burden at baseline.

CONCLUSION

The study findings suggest that CVC is a predictor of CAC progression and, potentially, of greater cardiovascular vulnerability. Treatment with cinacalcet combined with low doses of vitamin D slowed the progression of CAC compared to therapy using larger, varying doses of vitamin D.

25-Hydroxyvitamin D response to cholecalciferol supplementation in hemodialysis

BACKGROUND AND OBJECTIVES

Recent understanding of extrarenal production of calcitriol has led to the exploration of native vitamin D treatment in dialysis patients. This paper reports the pharmacokinetics of 25-hydroxyvitamin D response to 10,333 IU cholecalciferol given weekly in subjects on chronic dialysis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This randomized, double-blind, placebo-controlled trial of 15 weeks of oral cholecalciferol in subjects with stage 5 CKD requiring maintenance hemodialysis was conducted from November of 2007 to March of 2010. The time course of serum 25-hydroxyvitamin D was measured over the course of treatment. Additionally, blood was drawn at baseline and last visit for calcium, phosphorus, calcitriol, and parathyroid hormone levels.

RESULTS

The median (interquartile range) baseline 25-hydroxyvitamin D level was 13.3 (11.1-16.2) ng/ml for the treatment group and 15.2 (10.7-19.9) ng/ml for the placebo group. 25-hydroxyvitamin D steady state levels rose by 23.6 (19.2-29.9) ng/ml in the treatment group, and there was no change in the placebo group. Calcitriol levels also increased significantly in the treatment group. There were no significant changes in levels of calcium, albumin, phosphorus, and parathyroid hormone in either group.

CONCLUSIONS

Cholecalciferol (10,333 IU) given weekly in patients on chronic hemodialysis produces a steady state in 25-hydroxyvitamin D of approximately 24 ng/ml.

A local effect of CYP24 inhibition on lung tumor xenograft exposure to 1,25-dihydroxyvitamin D(3) is revealed using a novel LC-MS/MS assay

The vitamin D(3) catabolizing enzyme, CYP24, is frequently over-expressed in tumors, where it may support proliferation by eliminating the growth suppressive effects of 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)). However, the impact of CYP24 expression in tumors or consequence of CYP24 inhibition on tumor levels of 1,25(OH)(2)D(3)in vivo has not been studied due to the lack of a suitable quantitative method. To address this need, an LC-MS/MS assay that permits absolute quantitation of 1,25(OH)(2)D(3) in plasma and tumor was developed. We applied this assay to the H292 lung tumor xenograft model: H292 cells eliminate 1,25(OH)(2)D(3) by a CYP24-dependent process in vitro, and 1,25(OH)(2)D(3) rapidly induces CYP24 expression in H292 cells in vivo. In tumor-bearing mice, plasma and tumor concentrations of 1,25(OH)(2)D(3) reached a maximum of 21.6 and 1.70ng/mL, respectively, following intraperitoneal dosing (20μg/kg 1,25(OH)(2)D(3)). When co-administered with the CYP24 selective inhibitor CTA091 (250μg/kg), 1,25(OH)(2)D(3) plasma levels increased 1.6-fold, and tumor levels increased 2.6-fold. The tumor/plasma ratio of 1,25(OH)(2)D(3) AUC was increased 1.7-fold by CTA091, suggesting that the inhibitor increased the tumor concentrations of 1,25(OH)(2)D(3) independent of its effects on plasma disposition. Compartmental modeling of 1,25(OH)(2)D(3) concentration versus time data confirmed that: 1,25(OH)(2)D(3) was eliminated from plasma and tumor; CTA091 reduced the elimination from both compartments; and that the effect of CTA091 on tumor exposure was greater than its effect on plasma. These results provide evidence that CYP24-expressing lung tumors eliminate 1,25(OH)(2)D(3) by a CYP24-dependent process in vivo and that CTA091 administration represents a feasible approach to increase tumor exposure to 1,25(OH)(2)D(3).

Vitamin D binding protein and monocyte response to 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D: analysis by mathematical modeling

Vitamin D binding protein (DBP) plays a key role in the bioavailability of active 1,25-dihydroxyvitamin D (1,25(OH)₂D) and its precursor 25-hydroxyvitamin D (25OHD), but accurate analysis of DBP-bound and free 25OHD and 1,25(OH)₂D is difficult. To address this, two new mathematical models were developed to estimate: 1) serum levels of free 25OHD/1,25(OH)₂D based on DBP concentration and genotype; 2) the impact of DBP on the biological activity of 25OHD/1,25(OH)₂D in vivo. The initial extracellular steady state (eSS) model predicted that 50 nM 25OHD and 100 pM 1,25(OH)₂D), <0.1% 25OHD and <1.5% 1,25(OH)₂D are ‘free’ in vivo. However, for any given concentration of total 25OHD, levels of free 25OHD are higher for low affinity versus high affinity forms of DBP. The eSS model was then combined with an intracellular (iSS) model that incorporated conversion of 25OHD to 1,25(OH)₂D via the enzyme CYP27B1, as well as binding of 1,25(OH)₂D to the vitamin D receptor (VDR). The iSS model was optimized to 25OHD/1,25(OH)₂D-mediated in vitro dose-responsive induction of the vitamin D target gene cathelicidin (CAMP) in human monocytes. The iSS model was then used to predict vitamin D activity in vivo (100% serum). The predicted induction of CAMP in vivo was minimal at basal settings but increased with enhanced expression of VDR (5-fold) and CYP27B1 (10-fold). Consistent with the eSS model, the iSS model predicted stronger responses to 25OHD for low affinity forms of DBP. Finally, the iSS model was used to compare the efficiency of endogenously synthesized versus exogenously added 1,25(OH)₂D. Data strongly support the endogenous model as the most viable mode for CAMP induction by vitamin D in vivo. These novel mathematical models underline the importance of DBP as a determinant of vitamin D ‘status’ in vivo, with future implications for clinical studies of vitamin D status and supplementation.

[Vitamin D in the treatment of cardiorenal syndrome in patients with chronic nephropathy]

AIM

To determine place of vitamin D in prevention and treatment of cardiorenal syndrome (CRS) and chronic allograft nephropathy (CAN) in the aspect of myocardial and renal reparation.

METHODS AND MATERIAL

In Russia and the Netherlands we included in a randomized placebo controlled study 120 vitamin D deficient [25(OH) vitamin D<40 mol/l] recipients of asystolic and cadaveric donors. Patients were divided in 4 groups: paricalcitol (2-4 g/day) group (n=28), calcitriol (1-6 g/day orally) group (n=28), diet (1200-1800 IU/day of vitamin D with multivitamins and from foodstuffs) group (n=26), placebo with diet control group (n=27).

RESULTS

After 180 days degree of CAN according to the Banff classification was 1.24 and 1.22 in paricalcitol and calcitriol groups, respectively, compared with 1.43 and 1.68 in diet and placebo groups, respectively (p<0.05). Glomerular filtration rate (GFR) changed from 46.7 to 84.4, 81.4, 76.8, and 54.5 ml/min/1.73 m3 in paricalcitol, calcitriol, diet and placebo groups, respectively. Fluorescence activated cell scanning (FACS) analysis allowed to detect quantitative induction of SP+ cells amounting 7.4, 2.9 and 1.2%; 7.2, 2.7; and 1.1%; 6.1, 2.9 and 1.2%; 9.3, 1.3 and 0.7% of peripheral blood progenitors, renal epithelial cells, and cardiomyocytes in paricalcitol, calcitriol, diet and placebo groups, respectively. Levels of CD133, CD34, CD73, and CD105 were significantly elevated in patients of paricalcitol (median 161, range 0-834 copies), calcitriol (163, 0-721), and diet (119, 0-401) groups, compared with the placebo group (0,0-41), p<0.01. Level of nuclear vitamin D receptor (VDR) protein in renal tissue homogenizate and myocardium achieved 584, 599, 478, and 333 mole VRD/mg and 801, 715, 654, and 389 Φmole VRD/mg of protein in paricalcitol, calcitriol, diet and placebo groups, respectively (p<0.01). Circulating progenitor stem cells demonstrated comparatively high level of VDR expression--529, 526, 401, and 211 mole VRD/mg in CD133, CD34 cells; 432, 414, 303, and 290 mole VRD/mg in CD73, CD105 cells; 549, 558, 442, and 302 φmole VRD/mg in SP+ cells in paricalcitol, calcitriol, diet and placebo groups, respectively (p<0.05). Hypercalcemia was detected in 4(14%) patients in calcitriol group (p<0.001). Under influence of antihypertensive therapy arterial pressure decreased after transplantation from 180/101 to 143/87, 141/94, 147,102, and 165/101 mm Hg in paricalcitol, calcitriol, diet and placebo groups, respectively (p<0.01). NYHA heart failure functional class changed from 2.3 to 1.8, 1.9, 1.9, and 2.5 in paricalcitol, calcitriol, diet and placebo groups, respectively (p<0.01). In 6 months after transplantation average CCS scores were 533 (0-998), 611 (0-1712), 524 (122-1278) and 990 (120-1800) cells in paricalcitol, calcitriol, diet and placebo groups, respectively (p<0.05).

CONCLUSIONS

Vitamin D is an effective mean of prevention and treatment of CRS and CAN, stimulator of reparation of renal and myocardial tissues. Optimal for wide clinical practice is the use of active vitamin D analog paricalcitol (2-4 g/day) as well as special diet with multivitamins (up to 1800 IU of cholecalciferol).

The potential role of vitamin D enhanced foods in improving vitamin D status

Low vitamin D intake and status have been reported worldwide and many studies have suggested that this low status may be involved in the development of several chronic diseases. There are a limited number of natural dietary sources of vitamin D leading to a real need for alternatives to improve dietary intake. Enhancement of foods with vitamin D is a possible mode for ensuring increased consumption and thus improved vitamin D status. The present review examines studies investigating effects of vitamin D enhanced foods in humans and the feasibility of the approach is discussed.

Primary hyperparathyroidism - is vitamin D supplementation safe?

BACKGROUND

Vitamin D deficiency is commonly seen in patients with primary hyperparathyroidism. However, there is a widespread reluctance to provide vitamin D supplementation to this group of patients.

OBJECTIVE

This article examines the relationship between vitamin D deficiency and primary hyperparathyroidism and the effects of vitamin D supplementation.

CONCLUSION

Vitamin D deficiency exacerbates primary hyperparathyroidism and vice versa. With care, vitamin D supplementation can safely be given to selected patients with asymptomatic primary hyperparathyroidism and is suggested before deciding on medical or surgical management. Monitoring serum calcium concentration and urinary calcium excretion is recommended while achieving vitamin D repletion.