Vitamin D receptor: key roles in bone mineral pathophysiology, molecular mechanism of action, and novel nutritional ligands

The relationship between serum vitamin D, testosterone, and oxidative stress levels in women with sexual dysfunction: A case-controlled study

OBJECTIVE

Female sexual dysfunction (FSD) is highly prevalent and can result from hypovitaminosis D. Besides the role of vitamin D in normal bone development, studies showed it could reduce oxidative stress and lipid peroxidation. This prospective study aims to evaluate the relationship between serum vitamin D, testosterone, and oxidative stress levels in women with FSD.

MATERIALS AND METHODS

In this cross-sectional study, a total of 40 women with FSD (age range: 18-45 years) were randomly assigned into two groups of intervention and control. In the intervention group, patients received vitamin D 300,000 IU intramuscularly (IM) and then 50,000 IU orally once a week for four weeks. We measured the serum vitamin D, testosterone, and oxidative stress levels, as well as the Female Sexual Function Index (FSFI) at baseline and monthly for three months.

RESULTS

Serum testosterone levels significantly increased in the intervention group at the end of the third month (P = 0.014). Also, FSFI scores significantly improved (P < 0.01) in the intervention group compared to the control group. While there was positive a correlation between serum vitamin D levels with glutathione, total antioxidant capacity (TAC), testosterone, and FSFI score, there was a negative correlation between serum vitamin D levels with malondialdehyde (MDA), protein carbonyl, and nitric oxide.

CONCLUSION

We witnessed that women with FSD had low serum vitamin D levels. So, modifying serum vitamin D levels must be considered as a treatment option. Moreover, vitamin D supplementation improved testosterone, serum oxidative stress, and sexual function.

Proanthocyanidin B2 derived metabolites may be ligands for bile acid receptors S1PR2, PXR and CAR: an in silico approach

Bile acids (BAs) act as signaling molecules via their interactions with various nuclear (FXR, VDR, PXR and CAR) and G-protein coupled (TGR5, M3R, S1PR2) BA receptors. Stimulation of these BA receptors influences several processes, including inflammatory responses and glucose and xenobiotic metabolism. BA profiles and BA receptor activity are deregulated in cardiometabolic diseases; however, dietary polyphenols were shown to alter BA profile and signaling in association with improved metabolic phenotypes. We previously reported that supplementing mice with a proanthocyanidin (PAC)-rich grape polyphenol (GP) extract attenuated symptoms of glucose intolerance in association with changes to BA profiles, BA receptor gene expression, and/or downstream markers of BA receptor activity. Exact mechanisms by which polyphenols modulate BA signaling are not known, but some hypotheses include modulation of the BA profile via changes to gut bacteria, or alteration of ligand-availability via BA sequestration. Herein, we used an in silico approach to investigate putative binding affinities of proanthocyanidin B2 (PACB2) and PACB2 metabolites to nuclear and G-protein coupled BA receptors. Molecular docking and dynamics simulations revealed that certain PACB2 metabolites had stable binding affinities to S1PR2, PXR and CAR, comparable to that of known natural and synthetic BA ligands. These findings suggest PACB2 metabolites may be novel ligands of S1PR2, CAR, and PXR receptors.Communicated by Ramaswamy H. Sarma.

Molecular insights into the pathogenic impact of vitamin D deficiency in neurological disorders

Neurological disorders are the major cause of disability, leading to a decrease in quality of life by impairing cognitive, sensorimotor, and motor functioning. Several factors have been proposed in the pathogenesis of neurobehavioral changes, including nutritional, environmental, and genetic predisposition. Vitamin D (VD) is an environmental and nutritional factor that is widely distributed in the central nervous system's subcortical grey matter, neurons of the substantia nigra, hippocampus, thalamus, and hypothalamus. It is implicated in the regulation of several brain functions by preserving neuronal structures. It is a hormone rather than a nutritional vitamin that exerts a regulatory role in the pathophysiology of several neurological disorders, including Alzheimer's disease, Parkinson's disease, epilepsy, and multiple sclerosis. A growing body of epidemiological evidence suggests that VD is critical in neuronal development and shows neuroprotective effects by influencing the production and release of neurotrophins, antioxidants, immunomodulatory, regulation of intracellular calcium balance, and direct effect on the growth and differentiation of nerve cells. This review provides up-to-date and comprehensive information on vitamin D deficiency, risk factors, and clinical and preclinical evidence on its relationship with neurological disorders. Furthermore, this review provides mechanistic insight into the implications of vitamin D and its deficiency on the pathogenesis of neurological disorders. Thus, an understanding of the crucial role of vitamin D in the neurobiology of neurodegenerative disorders can assist in the better management of vitamin D-deficient individuals.

Vitamin D deficiency triggers intrinsic apoptosis by impairing SPP1-dependent antiapoptotic signaling in chronic hematogenous osteomyelitis

Chronic hematogenous osteomyelitis (CHOM) is a common bone disease characterized by the development of sequestra after bacterial infection. Emerging evidence has shown that vitamin D (VD) deficiency raises the risk of osteomyelitis, but the underlying mechanisms remain obscure. Here, we establish a CHOM model in VD diet-deficient mice by intravenous inoculation of Staphylococcus aureus. Whole-genome microarray analyses using osteoblast cells isolated from sequestra reveal significant downregulation of SPP1 (secreted phosphoprotein 1). Molecular basis investigations show that VD sufficiency activates the VDR/RXR (VD receptor/retinoid X receptor) heterodimer to recruit NCOA1 (nuclear receptor coactivator 1) and transactivate SPP1 in healthy osteoblast cells. Secreted SPP1 binds to the cell surface molecule CD40 to activate serine/threonine-protein kinase Akt1, which then phosphorylates forkhead box O3a (FOXO3a), blocking FOXO3a-mediated transcription. By contrast, VD deficiency impairs the NCOA1-VDR/RXR-mediated overexpression of SPP1, leading to the inactivation of Akt1 and the accumulation of FOXO3a. FOXO3a then upregulates the expression of the apoptotic genes BAX (Bcl2-associated X-protein), BID (BH3 interacting death domain), and BIM (Bcl2-interacting mediator of cell death), to induce apoptosis. Administration of the NCOA1 inhibitor gossypol to the CHOM mice also promotes the occurrence of sequestra. VD supplementation can reactivate the SPP1-dependent antiapoptotic signaling and improve the outcomes of CHOM. Collectively, our data reveal that VD deficiency promotes bone destruction in CHOM by the removal of SPP1-dependent antiapoptotic signaling.

Evaluation of Vitamin D Levels in Pediatric Patients With Recurrent Aphthous Stomatitis

BACKGROUND

Recurrent aphthous stomatitis is one of the most common oral mucosal diseases. It is characterized by recurrent painful attacks. Its etiology is unknown. Vitamin D (vit D) is a steroid vitamin with immunomodulatory and anti-inflammatory effects. It is thought that oral cavity diseases may occur in vitamin D deficiency. This study aimed to investigate vit D levels in pediatric patients with recurrent aphthous stomatitis.

METHODS

In this retrospective study, 86 children with recurrent aphthous stomatitis and 71 age-matched healthy children were included in the study. The 25-hydroxyvitamin D levels examined with the enzyme immune assay were recorded for both groups.

RESULTS

Serum vit D level was 12±4.5 ng/ml in the group with aphthous stomatitis and 31±7 ng/ml in the healthy group. A statistically significant difference was found in vit D levels between the two groups (p<0.001).

CONCLUSIONS

Vit D levels were significantly low in children with recurrent aphthous stomatitis. Our findings suggest that low vit D levels may be associated with recurrent aphthous stomatitis.

Relationship between Maternal Vitamin D Levels and Adverse Outcomes

Vitamin D (VD), a fat-soluble vitamin, has a variety of functions that are important for growth and development, including regulation of cell differentiation and apoptosis, immune system development, and brain development. As such, VD status during pregnancy is critical for maternal health, fetal skeletal growth, and optimal pregnancy outcomes. Studies have confirmed that adverse pregnancy outcomes, such as preeclampsia, low birth weight, neonatal hypocalcemia, poor postnatal growth, skeletal fragility, and increased incidence of autoimmune diseases, can be associated with low VD levels during pregnancy and infancy. Thus, there is growing interest in the role of VD during pregnancy. This review summarizes the potential adverse health outcomes of maternal VD status during pregnancy for both mother and offspring (gestational diabetes mellitus, hypertensive gestational hypertension, intrauterine growth restriction, miscarriage, stillbirth, and preterm birth) and discusses the underlying mechanisms (regulation of cytokine pathways, immune system processing, internal secretion, placental function, etc.) of VD in regulating each of the outcomes. This review aims to provide a basis for public health intervention strategies to reduce the incidence of adverse pregnancies.

Comparison of Validation Parameters for the Determination of Vitamin D3 in Commercial Pharmaceutical Products Using Traditional and Greener HPTLC Methods

Several analytical methods are documented for the estimation of vitamin D3 (VD3) in pharmaceuticals, food supplements, nutritional supplements, and biological samples. However, greener analytical methods for VD3 analysis are scarce in the literature. As a consequence, attempts were made to design and validate a greener “high-performance thin-layer chromatography (HPTLC)” method for VD3 estimation in commercial pharmaceutical products, as compared to the traditional HPTLC method. The greenness indices of both approaches were predicted by utilizing the “Analytical GREENness (AGREE)” method. Both traditional and greener analytical methods were linear for VD3 estimation in the 50–600 ng band−1 and 25–1200 ng band−1 ranges, respectively. The greener HPTLC strategy outperformed the traditional HPTLC strategy for VD3 estimation in terms of sensitivity, accuracy, precision, and robustness. For VD3 estimation in commercial tablets A–D, the greener analytical strategy was better in terms of VD3 assay over the traditional analytical strategy. The AGREE index of the traditional and greener analytical strategies was estimated to be 0.47 and 0.87, respectively. The AGREE analytical outcomes suggested that the greener analytical strategy had a superior greener profile to the traditional analytical strategy. The greener HPTLC strategy was regarded as superior to the traditional HPTLC methodology based on a variety of validation factors and pharmaceutical assays.

Vitamin D Receptor Polymorphisms Among the Turkish Population are Associated with Multiple Sclerosis

Multiple sclerosis (MS) is an inflammatory disease characterized by demyelination and axonal degeneration affecting the central nervous system. Among the genetic factors suggested to be associated with this disease are polymorphisms to the vitamin D receptor (VDR) gene. We tested the hypothesis that polymorphisms in the vitamin D receptor (VDR) gene are associated with MS. The aim of the study was to investigate the relationship of MS with the VDR gene Fok-I, Bsm-I and Taq-I polymorphisms among the Turkish population. This study contains 271 MS patients and 203 healthy controls. Genomic DNA was isolated from the samples and the VDR gene Fok-I, Bsm-I and Taq-I polymorphism regions were amplified by polymerase chain reaction (PCR). The PCR products were digested, and the genotypes were determined based on size of digested PCR products. Our results demonstrate associations between MS and the distribution of the VDR gene Fok-I T/T polymorphism genotype in a dominant model, VDR gene Fok-I T allele frequency, distribution of VDR gene Taq-I C/C polymorphism genotype in a dominant model and VDR gene Taq-I C allele frequency (Pearson test, p<0.05). However, there was no association between MS and the VDR gene Bsm-I polymorphisms for the genotype distribution (Pearson test, p>0.05) or allele frequency (Pearson test, p>0.05). Fok-I and Taq-I VDR gene polymorphisms are significantly associated with MS in dominant, homozygote and heterozygote inheritance models among the Turkish population.

Symptomatic spinal cord compression: an uncommon symptom in pseudohypoparathyroidism

We describe symptomatic spinal cord compression associated with pseudohypoparathyroidism (PHP) in a young female patient and reviewed similar cases previously reported in the literature. The characteristics of these cases were analyzed from etiology, clinical subtypes, symptoms, treatment, and prognosis. Neurological examination revealed functional upper extremities with bilateral lower extremity paraplegia. Laboratory tests showed hypocalcemia, hyperphosphatemia, and elevated parathyroid hormone; high-throughput sequencing showed a heterozygous GNAS mutation in exon 12, specifically c.1006C > T (p.R336W). Imaging findings showed multilevel spinal stenosis with significant spinal cord compression at the T2-T3 level. Seventeen cases with similar characteristics were reviewed. We found that the primary clinical manifestation of these patients was bilateral lower extremity spastic paraplegia. Multilevel spinal cord compression was commonly observed, especially at the lower cervical and upper thoracic spinal cord. Most of the patients had poor surgical treatment outcome and prognosis. Clinicians should be aware of paraplegia due to spinal cord compression as a rare neurological complication in patients with PHP. Early diagnosis and treatment of PHP is one basis for preventing severe spinal cord-related complications.

Dietary Fiber, Genetic Variations of Gut Microbiota-derived Short-chain Fatty Acids, and Bone Health in UK Biobank

CONTEXT

Dietary fiber intake may relate to bone health.

OBJECTIVE

To investigate whether dietary fiber intake is associated with bone mineral density (BMD), and the modification effect of genetic variations related to gut microbiota-derived short-chain fatty acids (SCFAs).

DESIGN

The associations of dietary fiber intake with estimated BMD derived from heel ultrasound and fractures were assessed in 224 630 and 384 134 participants from the UK Biobank.

SETTING

UK Biobank.

MAIN OUTCOME MEASURES

Estimated BMD derived from heel ultrasound.

RESULTS

Higher dietary fiber intake (per standard deviation) was significantly associated with higher heel-BMD (β [standard error] = 0.0047 [0.0003], P = 1.10 × 10-54). Similarly significant associations were observed for all the fiber subtypes including cereal, fruit (dried and raw), and vegetable (cooked and raw) (all P < .05). A positive association was found in both women and men but more marked among men except for dietary fiber in cooked vegetables (all Pinteraction < .05). A protective association was found between dietary fiber intake and hip fracture (hazard ratio, 95% confidence interval: 0.94, 0.89-0.99; P = 3.0 × 10-2). In addition, the association between dietary fiber and heel BMD was modified by genetically determined SCFA propionate production (Pinteraction = 5.1 × 10-3). The protective association between dietary fiber and heel BMD was more pronounced among participants with lower genetically determined propionate production.

CONCLUSIONS

Our results indicate that greater intakes of total dietary fiber and subtypes from various food sources are associated with higher heel-BMD. Participants with lower genetically determined propionate production may benefit more from taking more dietary fiber.

Prevalence of hypovitaminosis D in patients with juvenile osteochondritis dissecans

BACKGROUND

Juvenile osteochondritis dissecans (JOCD) is an acquired joint disease of unknown etiology that affects skeletally immature patients and has the potential to progress to osteoarthritis. Recent studies have reported a high prevalence of vitaminD deficiency in patients with osteochondral lesions. The aim of our study was to determine serum vitaminD levels in patients diagnosed with JOCD.

METHODS

Serum 25(OH)D levels of 31 patients (22 males) presenting 40 lesions (29 JOCD of the knee, and 11 of the ankle) were evaluated. The average age was 11.9±2.9years. HypovitaminosisD was defined as a value less than 30ng/mL and was divided into vitaminD insufficiency (20 to 30ng/mL) and vitaminD deficiency (<20ng/mL).

RESULTS

HypovitaminosisD was present in 45.2% of the evaluated patients (32.2% insufficiency and 13% deficiency). No significant differences were found in the mean values and incidence of hypovitaminosis between those patients in which the sample was taken in warm or cold season (P=.267 and P=.875, respectively). Patients who required surgery had a higher incidence of hypovitaminosis than those treated conservatively (60% versus 31%, P=.054). There was no correlation in the incidence of hypovitaminosis with sex, location, stability of the lesion, or if the lesion was uni- or bilateral.

CONCLUSION

In our series, almost half of the patients diagnosed with JOCD presented abnormal serum levels of vitaminD. A two-fold incidence of hypovitaminosis was observed in patients requiring surgical treatment compared to patients managed conservatively. The association found in this study does not imply causation, but it should be considered within the set of actions for the treatment of these injuries.

Pomegranate derivative urolithin A enhances vitamin D receptor signaling to amplify serotonin-related gene induction by 1,25-dihydroxyvitamin D

Mediated by the nuclear vitamin D receptor (VDR), the hormonally active vitamin D metabolite, 1,25-dihydroxyvitamin D₃ (1,25D), is known to regulate expression of genes impacting calcium and phosphorus metabolism, the immune system, and behavior. Urolithin A, a nutrient metabolite derived from pomegranate, possibly acting through AMP kinase (AMPK) signaling, supports respiratory muscle health in rodents and longevity in C. elegans by inducing oxidative damage-reversing genes and mitophagy. We show herein that urolithin A enhances transcriptional actions of 1,25D driven by co-transfected vitamin D responsive elements (VDREs), and dissection of this genomic effect in cell culture reveals: 1) urolithin A concentration-dependency, 2) occurrence with isolated natural VDREs, 3) nuclear receptor selectivity for VDR over ER, LXR and RXR, and 4) significant 3- to 13-fold urolithin A-augmentation of 1,25D-dependent mRNA encoding the widely expressed 1,25D-detoxification enzyme, CYP24A1, a benchmark vitamin D target gene. Relevant to potential behavioral effects of vitamin D, urolithin A elicits enhancement of 1,25D-dependent mRNA encoding tryptophan hydroxylase-2 (TPH2), the serotonergic neuron-expressed initial enzyme in tryptophan metabolism to serotonin. Employing quantitative real time-PCR, we demonstrate that TPH2 mRNA is induced 1.9-fold by 10 nM 1,25D treatment in culture of differentiated rat serotonergic raphe (RN46A-B14) cells, an effect magnified 2.5-fold via supplementation with 10 μM urolithin A. This potentiation of 1,25D-induced TPH2 mRNA by urolithin A is followed by a 3.1- to 3.7-fold increase in serotonin concentration in culture medium from the pertinent neuronal cell line, RN46A-B14. These results are consistent with the concept that two natural nutrient metabolites, urolithin A from pomegranate and 1,25D from sunlight/vitamin D, likely acting via AMPK and VDR, respectively, cooperate mechanistically to effect VDRE-mediated regulation of gene expression in neuroendocrine cells. Finally, gedunin, a neuroprotective natural product from Indian neem tree that impacts the brain derived neurotropic factor pathway, similarly potentiates 1,25D/VDR-action.

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Hormonal 1,25-dihydroxyvitamin D acts in brain to induce tryptophan hydroxylase-2.

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Urolithin A derived from ellagitannins in pomegranates curbs neuroinflammation.

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Urolithin A enhances the transcriptional actions of 1,25-dihydroxyvitamin D.

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Urolithin A raises 1,25-dihydroxyvitamin D-induced tryptophan hydroxylase-2 mRNA.

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Serotonin rises in raphe cells exposed to urolithin A and 1,25-dihydroxyvitamin D.

Vitamin D assessment and precision of clinical referrals: Insights gained from a teaching hospital in southern India

Objective:

Vitamin D deficiency is widely prevalent worldwide. This has led to a significant surge in referrals for vitamin D assessment in recent years. The cost-effectiveness and rationalization of this practice is uncertain. This study aimed to evaluate the referral pattern for vitamin D testing from a tertiary center in southern India.

Materials and Methods:

This was a cross-sectional study done over a period of one year (2017). A total of 95,750 individuals, referred for vitamin D screening were included in this study. Details regarding referring departments and indications for referral were obtained from the computerized hospital information processing system (CHIPS).

Results:

The study population exhibited a female preponderance (54.1%) with mean (SD) age of 40.3 (18.5) years. Overall, 44% were found to have vitamin D deficiency. Most of the referrals were from nephrology (15.4%), neurology (10.1%), and orthopedics (9.1%). Nevertheless, dermatology, the staff-clinic, and hematology which contributed to 3.3%, 1.7%, and 1.7% of referrals, had a higher proportion of vitamin D deficiency of 59.1%, 57.7%, and 64.6%, respectively. Although the most common indications for referral were generalized body aches (20.5%) and degenerative bone disorders (20.1%), the proportion of subjects with vitamin D deficiency referred for these indications were 46.1% and 41.6%, respectively. In contrast, chronic steroid use that accounted for 3.3% of the referrals had 59.1% of subjects who were deficient in vitamin D.

Conclusion:

To ensure a rational approach to vitamin D testing, clinicians ought to use their discretion to screen those truly at risk for vitamin D deficiency on a case to case basis and avoid indiscriminate testing of the same.

Association of Vitamin D Levels With Kidney Volume in Autosomal Dominant Polycystic Kidney Disease (ADPKD)

Vitamin D possesses renoprotective effects beyond mineral metabolism, potentially reducing arterial blood pressure and inflammation and vitamin D enzymes (CYP24A1 and CYP27B1) as well as vitamin D receptor (VDR) contribute to its homeostasis. In the present study, we aimed to determine vitamin D association with kidney volume, blood pressure parameters and inflammatory markers in ADPKD. This cross-sectional study, conducted from August 2011 through May 2016, evaluated 25(OH)D, 1,25(OH)2D and other hormonal/biochemical serum and urinary parameters, inflammatory markers and monocyte expression of VDR, CYP24A1, CYP27B1 in 74 ADPKD patients. The height-adjusted total kidney volume (htTKV) was determined by MRI and blood pressure (BP) measured through 24-h ambulatory BP monitoring (ABPM).Vitamin D insufficiency was present in 62% of patients and CYP24A1 was overexpressed in this group, raising a hypothesis of 25(OH)D increased catabolism. Serum 25(OH)D levels and VDR expression were negatively correlated with htTKV as was VDR with IL-6, IL-10, CRP, and NFκB. A multiple linear regression analysis with htTKV as dependent variable, including hypertension, CRP, eGFR, age, time since diagnosis, VDR, and 25(OH)D adjusted for season of the year showed that only the first three parameters were independent predictors of the former. There has been no association of serum 25(OH)D and VDR expression with ABPM parameters. Present findings suggested that low levels of serum 25(OH)D and VDR expression are associated with a higher kidney volume in ADPKD patients, but do not represent independent risk factors for htTKV.

Alternative binding sites at the vitamin D receptor and their ligands

In recent decades, the majority of ligands developed for the vitamin D receptor (VDR) bind at its deeply buried genomic ligand binding pocket. Theses ligands can be categorized into agonists and partial agonists/antagonists. A limited number of ligands, most of them peptides, bind the VDR‒coactivator binding site that is formed in the presence of an agonist and inhibit coactivator recruitment, and therefore transcription. Another solvent exposed VDR‒ligand binding pocket was identified for lithocholic acid, improving the overall stability of the VDR complex. Additional proposed interactions with VDR are discussed herein that include the alternative VDR‒ligand binding pocket that may mediate both non-genomic cellular responses and binding function 3 that was identified for the androgen receptor. Many VDR ligands increase blood calcium levels at therapeutic concentrations in vivo, thus the identification of alternative VDR‒ligand binding pockets might be crucial to develop non-calcemic and potent ligands for VDR to treat cancer and inflammatory disease.

Vitamin D and Vitamin D Receptor Gene in Osteoarthritis

Osteoarthritis is a degenerative, painful and irreversible disease that affects millions of people worldwide. The causes and mechanisms of osteoarthritis have not been fully understood. Vitamin D is an essential factor in bone metabolism. Its actions are mediated by the vitamin D receptor, a transcription factor that controls gene expression, thus maintaining calcium and phosphate homeostasis. Vitamin D has been hypothesized to play essential role in a number of musculoskeletal diseases including osteoarthritis, and its deficiency is prevalent among osteoarthritis patients. A large number of studies have been done regarding the effects of vitamin D in pathogenesis and progression of osteoarthritis, as well as its use a therapeutic agent. Up to date, studies have provided controversial results, and no consensus concerning this matter was achieved. With this review, we aim to explore current data on the possible role of vitamin D and its receptor in pathogenesis of osteoarthritis and assess the efficiency of vitamin D supplementation as a therapeutic strategy.

Vitamin D and critical illness: what endocrinology can learn from intensive care and vice versa

The prevalence of vitamin D deficiency in intensive care units ranges typically between 40 and 70%. There are many reasons for being or becoming deficient in the ICU. Hepatic, parathyroid and renal dysfunction additionally increases the risk for developing vitamin D deficiency. Moreover, therapeutic interventions like fluid resuscitation, dialysis, surgery, extracorporeal membrane oxygenation, cardiopulmonary bypass and plasma exchange may significantly reduce vitamin D levels. Many observational studies have consistently shown an association between low vitamin D levels and poor clinical outcomes in critically ill adults and children, including excess mortality and morbidity such as acute kidney injury, acute respiratory failure, duration of mechanical ventilation and sepsis. It is biologically plausible that vitamin D deficiency is an important and modifiable contributor to poor prognosis during and after critical illness. Although vitamin D supplementation is inexpensive, simple and has an excellent safety profile, testing for and treating vitamin D deficiency is currently not routinely performed. Overall, less than 800 patients have been included in RCTs worldwide, but the available data suggest that high-dose vitamin D supplementation could be beneficial. Two large RCTs in Europe and the United States, together aiming to recruit >5000 patients, have started in 2017, and will greatly improve our knowledge in this field. This review aims to summarize current knowledge in this interdisciplinary topic and give an outlook on its highly dynamic future.

High maternal osteocalcin levels during pregnancy is associated with low birth weight infants: A nested case-control study in China

BACKGROUND

Low birth weight infants (LBW) are at risk of chronic diseases in later life due to the disorder of energy metabolism during pregnancy. Osteocalcin (OC) has been identified as a hormone that regulate energy metabolism. However, few studies have researched on the associations between maternal serum OC levels and low birth weight infants.

OBJECTIONS

To examine the associations between maternal serum OC concentrations and LBW.

METHODS

This was a nested case-control study involving a total of 230 pregnant women delivering LBW and 382 control pregnant women (matched for infant gender, gestational age at blood draw, region of Maternity and Child Healthcare Hospital and maternal age in 1: (1-2) ratio). One serum sample was collected from each pregnant woman at 5-35 weeks' gestation. Pregnant women were divided into 3 groups (1st, 2nd and 3rd trimester group). There were 60 and 142 and 28 pregnant women delivering LBW in the first, second and third trimester, respectively. Similarly, there were 101 and 233 and 48 controls in the first, second and third trimester, respectively. Maternal serum OC and 25(OH)D concentrations were categorized into low and high levels, the low level used as reference in analyses. Binary logistic regression model was used to compute odd radio (ORs) for LBW according to levels of maternal serum OC and 25(OH)D.

RESULTS

Compared with the subjects in low level in first trimester, LBW was two times as likely to occur among pregnancy women with high serum OC concentrations (OR = 2.04, 95%CI:1.05-3.96). After adjusted for confounding factors, a significant positive relationship still existed (adjusted ORs = 2.29, 95%CI: 1.11-4.72). In second trimester, women in high level of serum OC had nearly 1.6 times the risk of delivering LBW infants as those in the low level (OR = 1.55, 95%CI: 1.01-2.37). After adjusted for confounding factors, the ORs increased (ORs = 1.59, 95%CI:1.03-2.45). No significant associations were found between maternal serum OC levels and LBW in third trimester. In addition, there were no associations between maternal 25(OH)D concentrations and LBW during pregnancy.

CONCLUSION

High maternal serum OC levels in the first or the second trimester during pregnancy may be associated with the risk of LBW.

Effects of Single Vitamin D₃ Injection (200,000 Units) on Serum Fibroblast Growth Factor 23 and Sclerostin Levels in Subjects with Vitamin D Deficiency

BACKGROUND

Vitamin D deficiency remains common in all age groups and affects skeletal and non-skeletal health. Fibroblast growth factor 23 is a bone-derived hormone that regulates phosphate and 1,25-dihydroxyvitamin D homeostasis as a counter regulatory factor. 1,25-Dihydroxyvitamin D stimulates fibroblast growth factor 23 synthesis in bone, while fibroblast growth factor 23 suppresses 1,25-dihydroxyvitamin D production in the kidney. The aim of this study was to evaluate the effects of vitamin D₃ intramuscular injection therapy on serum fibroblast growth factor 23 concentrations, and several other parameters associated with bone metabolism such as sclerostin, dickkopf-1, and parathyroid hormone.

METHODS

A total of 34 subjects with vitamin D deficiency (defined by serum 25-hydroxyvitamin D levels below 20 ng/mL) were randomly assigned to either the vitamin D injection group (200,000 units) or placebo treatment group. Serum calcium, phosphate, urine calcium/creatinine, serum 25-hydroxyvitamin D, fibroblast growth factor 23, sclerostin, parathyroid hormone, and dickkopf-1 levels were serially measured after treatment.

RESULTS

Comparing the vitamin D injection group with the placebo group, no significant changes were observed in serum fibroblast growth factor 23, parathyroid hormone, or dickkopf-1 levels. Serum sclerostin concentrations transiently increased at week 4 in the vitamin D group. However, these elevated levels declined later and there were no statistically significant differences as compared with baseline levels.

CONCLUSION

Serum fibroblast factor 23, sclerostin, parathyroid hormone, and dickkopf-1 levels were not affected significantly by single intramuscular injection of vitamin D₃.

1,25(OH)2 vitamin D3 signalling on immature rat Sertoli cells: gamma-glutamyl transpeptidase and glucose metabolism

1α,25-Dihydroxyvitamin D₃ (1,25-D₃) is critical for the maintenance of normal male reproduction since reduced fertility is observed in vitamin D-deficient rats. Gamma-glutamyl transpeptidase (GGT) is a membrane-bound enzyme that is localized on Sertoli cells and catalyses the transfer of the gamma-glutamyl residues to an amino acid or peptide acceptor. Sertoli cells are also responsible for providing nutrients, as lactate, to the development of germ cells. The aim of this study was to investigate the effect and the mechanism of action of 1,25-D₃ on GGT on Sertoli cell functions from 30-day-old immature rat testis. Results demonstrated that 1,25-D₃ stimulates GGT activity at Sertoli cells plasma membrane through a PKA-dependent mechanism of action, which was not dependent of active de novo protein synthesis. The hormone increases glucose uptake, as well as lactate production and release by Sertoli cells without altering the reactive oxygen species (ROS) generation. In addition, 1,25-D₃ did not change reduced glutathione (GSH) amount or oxygen consumption, and diminished Sertoli cell death. These findings demonstrate that 1,25-D₃ stimulatory effect on GGT activity, glucose uptake, LDH activity and lactate production seem to be an important contribution of Sertoli cells for germ cells nutrition and for a full and active ongoing spermatogenesis.

Vitamin-D measurement in patients with adolescent idiopathic scoliosis

Our retrospective study compared vitamin-D levels in 229 patients with adolescent idiopathic scoliosis (AIS) and 389 age-matched controls, and evaluated the correlation between vitamin-D levels and sex, Cobb's angle, and serum levels of calcium (Ca), phosphorus, and alkaline phosphatase in the AIS group. Vitamin-D levels were lower in the AIS group, with no sex-specific effects, indicative of a possible vitamin-D resistance in AIS. Vitamin-D levels correlated positively with Ca levels and negatively with Cobb's angle, indicative of a possible role of vitamin D in the etiopathogenesis of AIS. Patients with AIS should be monitored for vitamin-D deficiency/insufficiency.

Characterization of cytochrome P450 CYP109E1 from Bacillus megaterium as a novel vitamin D3 hydroxylase

In this study the ability of CYP109E1 from Bacillus megaterium to metabolize vitamin D₃ (VD₃) was investigated. In an in vitro system using bovine adrenodoxin reductase (AdR) and adrenodoxin (Adx_4-108), VD₃ was converted by CYP109E1 into several products. Furthermore, a whole-cell system in B. megaterium MS941 was established. The new system showed a conversion of 95% after 24h. By NMR analysis it was found that CYP109E1 catalyzes hydroxylation of VD₃ at carbons C-24 and C-25, resulting in the formation of 24(S)-hydroxyvitamin D₃ (24S(OH)VD₃), 25-hydroxyvitamin D₃ (25(OH)VD₃) and 24S,25-dihydroxyvitamin D₃ (24S,25(OH)₂VD₃). Through time dependent whole-cell conversion of VD₃, we identified that the formation of 24S,25(OH)₂VD₃ by CYP109E1 is derived from VD₃ via the intermediate 24S(OH)VD₃. Moreover, using docking analysis and site-directed mutagenesis, we identified important active site residues capable of determining substrate specificity and regio-selectivity. HPLC analysis of the whole-cell conversion with the I85A-mutant revealed an increased selectivity towards 25-hydroxylation of VD₃ compared with the wild type activity, resulting in an approximately 2-fold increase of 25(OH)VD₃ production (45mgl^-1day^-1) compared to wild type (24.5mgl^-1day^-1).

Fracture Risk in Relation to Serum 25-Hydroxyvitamin D and Physical Activity: Results from the EPIC-Norfolk Cohort Study

Vitamin D deficiency and physical inactivity have been associated with bone loss and fractures, but their combined effect has scarcely been studied either in younger or older adults. Therefore, we aimed to assess the associations between physical activity, age and 25-hydroxyvitamin D (25(OH)D) status separately and in combination with the incidence of fracture risk in the EPIC-Norfolk cohort study. Baseline (1993-1998) self-reported physical activity and serum 25(OH)D concentrations at follow-up (1998-2000) were collected in 14,624 men and women (aged 42-82 y between 1998 and 2000). Fracture incidence was ascertained up to March 2015. Cox proportional hazard model was used to determine HRs of fractures by plasma 25(OH)D (<30, 30 to <50, 50 to <70, 70 to <90, >90 nmol/L), age (<65 y and >65 y) and physical activity (inactive and active) categories, by follow-up time per 20 nmol/L increase in serum 25(OH)D and to explore age-25(OH)D and physical activity-25(OH)D interactions. The age-, sex-, and month-adjusted HRs (95% CIs) for all fractures (1183 fractures) by increasing vitamin D category were not significantly different. With additional adjustment for body mass index, smoking status, alcohol intake, supplement use and history of fractures, the fracture risk was 29% lower in those participants with 50 to 70 nmol/L compared with those in the lowest quintile (<30 nmol/L). Physical inactivity based on a single baseline assessment was not associated with fracture risk. Vitamin D status appeared inversely related to fractures in middle aged adults. In older adults, the relationship between vitamin D status and fracture risk was observed to be J-shaped. Clinical and public health practice in vitamin D supplementation could partially explain these findings, although definitive conclusions are difficult due to potential changes in exposure status over the long follow up period.

Wnt5a Supports Osteogenic Lineage Decisions in Embryonic Stem Cells

The specification of pluripotent stem cells into the bone-forming osteoblasts has been explored in a number of studies. However, the current body of literature has yet to adequately address the role of Wnt glycoproteins in the differentiation of pluripotent stem cells along the osteogenic lineage. During mouse embryonic stem cell (ESC) in vitro osteogenesis, the noncanonical WNT5a is expressed early on. Cells either sorted by their positive WNT5a expression or when supplemented with recombinant WNT5a (rWNT5a) during a 2-day window showed significantly enhanced osteogenic yield. Mechanistically, rWNT5a supplementation upregulated protein kinase C (PKC), calcium/calmodulin-dependent kinase II (CamKII) and c-Jun N-terminal kinase (JNK) activity while antagonizing the key effector of canonical Wnt signaling: β-catenin. Conversely, when recombinant WNT3a (rWNT3a) or other positive regulators of β-catenin were employed during this same time window there was a decrease in osteogenic marker expression. However, if rWNT3a was supplemented during a time window following rWNT5a treatment, osteogenic differentiation was enhanced both in murine and human ESCs. Elucidating the role of these WNT ligands in directing the early stages of osteogenesis has the potential to considerably improve tissue engineering protocols and applications for regenerative medicine.

Stage I and II Stress Incontinence (SIC): High dosed vitamin D may improve effects of local estriol

After the age of 55 almost every third woman suffers from conditions of the incapability to retain urine when the intra-abdominal pressure is raised by different causes. So called stress incontinence. It’ s caused by a predisposition in the family, weakness of the tissue, physical strain, deficiency in the metabolism, especially an increasing local estrogen deficiency and a local and systemic vitamin D deficiency. Patients: We evaluated the data of 60 meno- and postmenopausal female patients with a stress incontinence (SIC). All had a SIC in spite of a former local estriol treatment with a treatment of OeKolp® forte (= 0.5 mg estriol/ov), 3 times a week, for 6 weeks and in spite of a regular pelvic floor exercise for 6 weeks in the morning and in the evening, according to the protocol. Thirty were in stage I SIC and 30 were in stage II SIC. Method: We evaluated vitamin-D-levels in serum of our 60 postmenopausal women. Only 20% of this group had good vitamin D-levels. The medical intervention combined estriol (0.5 mg) together with high dosed vitamin D (12.500 I.U.) locally 3 times a week for a period of 6 weeks. The patients also had the instruction to continue their daily exercises in pelvic floor (morning and evening, due to their protocol). After six weeks of treatment the vitamin D level in serum was defined and correlated to the patients condition (symptomatic of stress incontinence, protocol of micturitions, Pad-test). Results: About one-third of women from our test assigned to be now capable of retaining urine. More than one-third of our patients cleared a profit of treatment. They reported mimimum regression about 25% of volume of incontinence. Therefore more than 2-third of our women being incapable of retaining urine improved their body conditions by using a combination of locally administered etriol and high dosed vitamin D. Conclusion: Stress incontinence (being incapable of retaining urine when the intra-abdominal pressure arises) in lower and middle grade, improves their body conditions under a combination of local administered estriol and vitamin D. This small study is not representative. We need much bigger studies with much more dates and with a follow up.

PTH and Vitamin D

PTH and Vitamin D are two major regulators of mineral metabolism. They play critical roles in the maintenance of calcium and phosphate homeostasis as well as the development and maintenance of bone health. PTH and Vitamin D form a tightly controlled feedback cycle, PTH being a major stimulator of vitamin D synthesis in the kidney while vitamin D exerts negative feedback on PTH secretion. The major function of PTH and major physiologic regulator is circulating ionized calcium. The effects of PTH on gut, kidney, and bone serve to maintain serum calcium within a tight range. PTH has a reciprocal effect on phosphate metabolism. In contrast, vitamin D has a stimulatory effect on both calcium and phosphate homeostasis, playing a key role in providing adequate mineral for normal bone formation. Both hormones act in concert with the more recently discovered FGF23 and klotho, hormones involved predominantly in phosphate metabolism, which also participate in this closely knit feedback circuit. Of great interest are recent studies demonstrating effects of both PTH and vitamin D on the cardiovascular system. Hyperparathyroidism and vitamin D deficiency have been implicated in a variety of cardiovascular disorders including hypertension, atherosclerosis, vascular calcification, and kidney failure. Both hormones have direct effects on the endothelium, heart, and other vascular structures. How these effects of PTH and vitamin D interface with the regulation of bone formation are the subject of intense investigation.

Vitamin D and Its Relevance in the Etiopathogenesis of Oral Cavity Diseases

Vitamin D belongs to a group of fat-soluble secosteroids which assume many roles in the human organism. In humans the most important forms are vitamin D3 and vitamin D2. Their primary function is the regulation of the calcium and phosphorus balance, which promote the growth of healthy bony tissue. Studies over the past few years have revealed a much wider role of vitamin D involving the aging processes, carcinogenesis, the carbohydrate balance as well as the effects on the course of various infections. In this paper we discuss the basic functions of vitamin D in the human body and the mechanisms of its activity and we summarize recent reports on the impact of vitamin D on the oral cavity with a special emphasis on autoimmunologic diseases, including: recurrent aphthous stomatitis, Behçet syndrome and Sjögren syndrome.

Low 25(OH) D serum levels are related with hip fracture in postmenopausal women: a matched case-control study

Purpose

There is limited information on the prevalence of vitamin D deficiency among patients diagnosed with hip fracture in the Chinese Han population. Therefore, the aim of this study was to assess the effects of change in the serum levels of 25-hydroxyvitamin D [25(OH) D] and intact parathyroid hormone (iPTH) among postmenopausal women in North China with confirmed hip fracture.

Methods

This study was done from May 1, 2012 to April 30, 2014. Three hundred and forty-nine postmenopausal women who were diagnosed with first-ever hip fracture and 349 matched controls without fracture were used for this study. The 25(OH) D, iPTH, alkaline phosphatase, calcium, and phosphorus levels were measured in fasting venous blood samples collected from the subjects. A predesigned questionnaire was used to collect information on covariates for multivariate analyses to evaluate the hypothesized relationship between vitamin D deficiency and fracture risk.

Results

The serum 25(OH) D levels were found to be significantly (P < 0.0001) lower in hip fracture patients than in the controls [37.0 (interquartile range [IQR] 28.0–48.0) nmol/L vs. 41.3 (IQR 32.0–54.5) nmol/L; P < 0.0001], and the iPTH levels were significantly higher in the former group [10.2 (IQR 6.3–14.9) pmol/L vs. 5.8 (IQR 4.1–6.6) pmol/L; P < 0.0001]. Further, a 25(OH) D level ≤50 nmol/L was found to independently indicate the occurrence of hip fracture [odds ratio (OR), 3.023; 95 % confidence interval (CI) 2.154–4.298], as well as hip fracture with concomitant upper limb fracture (OR 4.473; 95 % CI 2.984–10.532). Similarly, a serum iPTH level ≥6.8 pmol/L independently indicated the development of hip fracture (OR 2.498; 95 % CI 1.764–3.942), as well as hip fracture with concomitant upper limb fracture (OR 3.254; 95 % CI 1.998–7.984).

Conclusions

Vitamin D insufficiency and secondary hyperparathyroidism were found to be common problems in the sample of postmenopausal women who had experienced hip fracture. Monitoring the alterations in the serum levels of 25(OH) D and iPTH could be applied clinically as independent risk factors for hip fracture.

A High-Calcium and Phosphate Rescue Diet and VDR-Expressing Transgenes Normalize Serum Vitamin D Metabolite Profiles and Renal Cyp27b1 and Cyp24a1 Expression in VDR Null Mice

Vitamin D receptor (VDR)-mediated 1,25-dihydroxyvitamin D3 (1,25(OH)2D3)-dependent gene expression is compromised in the VDR null mouse. The biological consequences include: hypocalcemia, hypophosphatemia, elevated parathyroid hormone (PTH) and 1,25(OH)2D3, and consequential skeletal abnormalities. CYP24A1 is a cytochrome P450 enzyme that is involved in the side chain oxidation and destruction of both 1,25(OH)2D3 and 25-hydroxyvitamin D3 (25-OH-D3). In the current studies, we used liquid chromatography-tandem mass spectrometry technology to compare the metabolic profiles of VDR null mice fed either a normal or a calcium and phosphate-enriched rescue diet and to assess the consequence of transgenic expression of either mouse or human VDR genes in the same background. Serum 1,25(OH)2D3 levels in VDR null mice on normal chow were highly elevated (>3000 pg/mL) coincident with undetectable levels of catabolites such as 24,25-(OH)2D3 and 25-OH-D3-26,23-lactone normally observed in wild-type mice. The rescue diet corrected serum Ca(++), PTH, and 1,25(OH)2D3 values and restored basal expression of Cyp24a1 as evidenced by both renal expression of Cyp24a1 and detection of 24,25-(OH)2D3 and the 25-OH-D3-26,23-lactone. Unexpectedly, this diet also resulted in supranormal levels of 3-epi-24,25-(OH)2D3 and 3-epi-25-OH-D3-26,23-lactone. The reappearance of serum 24,25-(OH)2D3 and renal Cyp24a1 expression after rescue suggests that basal levels of Cyp24a1 may be repressed by high PTH. Introduction of transgenes for either mouse or human VDR also normalized vitamin D metabolism in VDR null mice, whereas this metabolic pattern was unaffected by a transgene encoding a ligand binding-deficient mutant (L233S) human VDR. We conclude that liquid chromatography-tandem mass spectrometry-based metabolic profiling is an ideal analytical method to study mouse models with alterations in calcium/phosphate homeostasis.

Glia in the cytokine-mediated onset of depression: fine tuning the immune response

Major depressive disorder (MDD) is a mood disorder of multifactorial origin affecting millions of people worldwide. The alarming estimated rates of prevalence and relapse make it a global public health concern. Moreover, the current setback of available antidepressants in the clinical setting is discouraging. Therefore, efforts to eradicate depression should be directed towards understanding the pathomechanisms involved in the hope of finding cost-effective treatment alternatives. The pathophysiology of MDD comprises the breakdown of different pathways, including the hypothalamus-pituitary-adrenal (HPA) axis, the glutamatergic system, and monoaminergic neurotransmission, affecting cognition and emotional behavior. Inflammatory cytokines have been postulated to be the possible link and culprit in the disruption of these systems. In addition, evidence from different studies suggests that impairment of glial functions appears to be a major contributor as well. Thus, the intricate role between glia, namely microglia and astrocytes, and the central nervous system's (CNSs) immune response is briefly discussed, highlighting the kynurenine pathway as a pivotal player. Moreover, evaluations of different treatment strategies targeting the inflammatory response are considered. The immuno-modulatory properties of vitamin D receptor (VDR) suggest that vitamin D is an attractive and plausible candidate in spite of controversial findings. Further research investigating the role of VDR in mood disorders is warranted.

Monocyte-macrophage differentiation of acute myeloid leukemia cell lines by small molecules identified through interrogation of the Connectivity Map database

The transcription factor C/EBPα is required for granulocytic differentiation of normal myeloid progenitors and is frequently inactivated in acute myeloid leukemia (AML) cells. Ectopic expression of C/EBPα in AML cells suppresses proliferation and induces differentiation suggesting that restoring C/EBPα expression/activity in AML cells could be therapeutically useful. Unfortunately, current approaches of gene or protein delivery in leukemic cells are unsatisfactory. However, "drug repurposing" is becoming a very attractive strategy to identify potential new uses for existing drugs. In this study, we assessed the biological effects of candidate C/EBPα-mimetics identified by interrogation of the Connectivity Map database. We found that amantadine, an antiviral and anti-Parkinson agent, induced a monocyte-macrophage-like differentiation of HL60, U937, Kasumi-1 myeloid leukemia cell lines, as indicated by morphology and differentiation antigen expression, when used in combination with suboptimal concentration of all trans retinoic acid (ATRA) or Vit D3. The effect of amantadine depends, in part, on increased activity of the vitamin D receptor (VDR), since it induced VDR expression and amantadine-dependent monocyte-macrophage differentiation of HL60 cells was blocked by expression of dominant-negative VDR. These results reveal a new function for amantadine and support the concept that screening of the Connectivity Map database can identify small molecules that mimic the effect of transcription factors required for myelo-monocytic differentiation.

Vitamin D—update for the pediatric rheumatologists

Vitamin D, upon its discovery one century ago, was classified as a vitamin. This classification still greatly affects our perception about its biological role. 1,25(OH)2D (now known as the D hormone) is a pleiotropic steroid hormone that has multiple biologic effects. It is integral to the regulation of calcium homeostasis and bone turnover as well as having anti-proliferative, pro-differentiation, anti-bacterial, immunomodulatory and anti-inflammatory properties within the body in various cells and tissues. Vitamin D (cholecalciferol) should be considered a nutritional substrate that must be ingested or synthesized in sufficient amounts for the further synthesis of the very important regulatory steroid hormone (D hormone), especially in patients with pediatric rheumatic diseases (PRD). Vitamin D insufficiency or deficiency was shown to be pandemic and associated with numerous chronic inflammatory and malignant diseases and even with increased risk of mortality. Several studies have demonstrated that a high percentage of children with pediatric rheumatic diseases (PRD-e.g., JIA, jSLE) have a vitamin D deficiency or insufficiency which might correlate with disease outcome and flares. Glucocorticoids used to treat disease may have a regulatory effect on vitamin D metabolism which can additionally aggravate bone turnover in PRD. An effort to define the optimal serum 25(OH)D concentrations for healthy children and adults was launched in 2010 but as of now there are no guidelines about supplementation in PRD. In this review we have tried to summarize the strong evidence now suggesting that as the knowledge of the optimal approach to diagnosis and treatment PRD has evolved, there is also an emerging need for vitamin D supplementation as an adjunct to regular disease treatment. So in accordance with new vitamin D recommendations, we recommend that a child with rheumatic disease, especially if treated with steroids, needs at least 2-3 time higher doses of vitamin D than the dose recommended for age (approximately 2000 UI/day). Vitamin D supplementation has become an appealing and important adjunct treatment option in PRD.

Serum Levels of 25-hydroxyvitamin D and Functional Outcome in Older Patients with Hip Fracture

The aim was to assess prognostic value of serum 25-hydroxyvitamin D (25[OH] D) levels in older Chinese patients with hip fracture. From June, 2012 to February, 2014, older patients with hip fracture were included. Serum 25(OH) D levels were measured at admission. The functional evaluation at the time of discharge was performed by the Barthel Index. In the 66 patients with an unfavorable outcome, serum 25(OH) D levels were lower compared with those with a favorable outcome. In multivariate analyses, there was an increased risk of unfavorable outcome associated with serum 25(OH) D levels ≤ 20 ng/ml (OR 5.25, 95% CI: 3.12-8.16). Our data supported an association between serum 25[OH] D levels at admission and short-term prognosis in Chinese older patients with hip fracture.

UV-activated 7-dehydrocholesterol-coated titanium implants promote differentiation of human umbilical cord mesenchymal stem cells into osteoblasts

Vitamin D metabolites are essential for bone regeneration and mineral homeostasis. The vitamin D precursor 7-dehydrocholesterol can be used after UV irradiation to locally produce active vitamin D by osteoblastic cells. Furthermore, UV-irradiated 7-dehydrocholesterol is a biocompatible coating for titanium implants with positive effects on osteoblast differentiation. In this study, we examined the impact of titanium implants surfaces coated with UV-irradiated 7-dehydrocholesterol on the osteogenic differentiation of human umbilical cord mesenchymal stem cells. First, the synthesis of cholecalciferol (D3) was achieved through the incubation of the UV-activated 7-dehydrocholesterol coating for 48 h at 23℃. Further, we investigated in vitro the biocompatibility of this coating in human umbilical cord mesenchymal stem cells and its potential to enhance their differentiation towards the osteogenic lineage. Human umbilical cord mesenchymal stem cells cultured onto UV-irradiated 7-dehydrocholesterol-coated titanium implants surfaces, combined with osteogenic supplements, upregulated the gene expression of several osteogenic markers and showed higher alkaline phosphatase activity and calcein blue staining, suggesting increased mineralization. Thus, our results show that the use of UV irradiation on 7-dehydrocholesterol -treated titanium implants surfaces generates a bioactive coating that promotes the osteogenic differentiation of human umbilical cord mesenchymal stem cells, with regenerative potential for improving osseointegration in titanium-based bone anchored implants.

Vitamin D and alternative splicing of RNA

The active form of vitamin D (1α,25-dihydroxyvitamin D, 1,25(OH)2D) exerts its genomic effects via binding to a nuclear high-affinity vitamin D receptor (VDR). Recent deep sequencing analysis of VDR binding locations across the complete genome has significantly expanded our understanding of the actions of vitamin D and VDR on gene transcription. However, these studies have also promoted appreciation of the extra-transcriptional impact of vitamin D on gene expression. It is now clear that vitamin D interacts with the epigenome via effects on DNA methylation, histone acetylation, and microRNA generation to maintain normal biological functions. There is also increasing evidence that vitamin D can influence pre-mRNA constitutive splicing and alternative splicing, although the mechanism for this remains unclear. Pre-mRNA splicing has long been thought to be a post-transcription RNA processing event, but current data indicate that this occurs co-transcriptionally. Several steroid hormones have been recognized to coordinately control gene transcription and pre-mRNA splicing through the recruitment of nuclear receptor co-regulators that can both control gene transcription and splicing. The current review will discuss this concept with specific reference to vitamin D, and the potential role of heterogeneous nuclear ribonucleoprotein C (hnRNPC), a nuclear factor with an established function in RNA splicing. hnRNPC, has been shown to be involved in the VDR transcriptional complex as a vitamin D-response element-binding protein (VDRE-BP), and may act as a coupling factor linking VDR-directed gene transcription with RNA splicing. In this way hnRNPC may provide an additional mechanism for the fine-tuning of vitamin D-regulated target gene expression. This article is part of a Special Issue entitled '17th Vitamin D Workshop'.

Serum levels of 25-hydroxyvitamin D and functional outcome among postmenopausal women with hip fracture

Objective

The main objective of the current study was to assess the distribution and its prognostic value of serum 25-hydroxyvitamin D (25[OH] D) levels assessed at admission in Chinese postmenopausal women with hip fracture.

Methods

From January 1, 2012 to December 31, 2013, all postmenopausal women with first-ever hip fracture were recruited to participate in the study. Serum 25[OH] D levels were measured at admission. The functional evaluation at the time of discharge was performed by the Barthel Index (BI). The prognostic value of 25[OH] D to predict the functional outcome within discharge was analyzed by logistic regression analysis, after adjusting for the possible confounders.

Results

In our study, 261 patients were included and assessed. In the 76 patients with an unfavorable functional outcome, serum 25(OH) D levels were lower compared with those in patients with a favorable outcome [11.8(IQR, 9.9–16.1)ng/ml; 16.8(IQR, 13.6–21.4)ng/ml, respectively; P<0.0001]. In multivariate analysis, there was an increased risk of unfavorable outcome associated with serum 25(OH) D levels ≤ 20ng/ml (OR 5.24, 95%CI: 3.11–8.15; P<0.0001) after adjusting for possible confounders.

Conclusions

Our data support an association between serum 25[OH] D levels and prognosis in Chinese postmenopausal women with hip fracture.

Positive association of vitamin D receptor gene variations with multiple sclerosis in South East Iranian population

Among the factors postulated to play a role in MS susceptibility, the role of vitamin D is outstanding. Since the function of vitamin D receptor (VDR) represents the effect of vitamin D on the body and genetic variations in VDR gene may affect its function, we aim to highlight the association of two VDR gene polymorphisms with MS susceptibility. In current study, we recruited 113 MS patients and 122 healthy controls. TaqI (rs731236) and ApaI (rs7975232) genetic variations in these two groups were evaluated using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. All genotype and allele frequencies in both variations showed association with the disease status. However, to find the definite connection between genetic variations in VDR gene and MS disease in a population of South East of Iran, more researches on gene structure and its function with regard to patients' conditions are required.

The claudin-16 channel gene is transcriptionally inhibited by 1,25-dihydroxyvitamin D

NEW FINDINGS

What is the central question of this study? In the kidney, the bulk of the filtered Mg(2+) is reabsorbed in the thick ascending limb by paracellular conductance, mediated by the tight junction protein, claudin-16, which is encoded by the gene CLDN16. The role of 1,25-dihydroxyvitamin D [1,25(OH)2 VitD] in renal Mg(2+) handling is unclear. We aimed to explore the molecular mechanisms underlying the effect of 1,25(OH)2 VitD on claudin-16-mediated Mg(2+) transport. What is the main finding and its importance? Paracellular, claudin-16-mediated Mg(2+) transport is transcriptionally repressed by 1,25(OH)2 VitD, probably via a Ca(2+)-sensing receptor-dependent mechanism. This renal effect of 1,25(OH)2 VitD may serve as an adaptive mechanism to the 1,25(OH)2 VitD-induced enteric hyperabsorption of dietary Mg(2+). Magnesium is reabsorbed in the thick ascending limb by paracellular conductance, mediated by the CLDN16-encoded tight junction protein, claudin-16. However, the role of 1,25-dihydroxyvitamin D [1,25(OH)2 VitD] in renal Mg(2+) handling is unclear. We have shown that Mg(2+) depletion increases and 1,25(OH)2 VitD inhibits CLDN16 transcription. We have now explored further the molecular mechanisms underlying the effect of 1,25(OH)2 VitD on claudin-16-mediated Mg(2+) transport. Adult mice received parenteral 1,25(OH)2 VitD or 1,25(OH)2 VitD combined with either high-Mg(2+) or low-Mg(2+) diets. Administration of 1,25(OH)2 VitD enhanced urinary excretion of Mg(2+) and Ca(2+). The 1,25(OH)2 VitD also increased renal Ca(2+)-sensing receptor (CaSR) mRNA and decreased renal claudin-16 and claudin-19 mRNA and claudin-16 protein, but did not affect renal claudin-2 mRNA. The 1,25(OH)2 VitD reversed the expected increase in claudin-16 mRNA in Mg(2+)-depleted animals. Comparably treated HEK 293 cells showed similar changes in claudin-16 mRNA, but 1,25(OH)2 VitD did not alter mRNA of the TRPM6 Mg(2+) channel. A luciferase reporter vector containing 2.5 kb of 5'-flanking DNA sequence from human CLDN16 (hCLDN16) was transfected into HEK 293 and OK cells. The hCLDN16 promoter activity was modestly decreased by 1,25(OH)2 VitD, but markedly inhibited in HEK 293 cells coexpressing CaSR. Coexpression in OK cells of dominant-negative CaSR completely abolished inhibition of hCLDN16 promoter activity by 1,25(OH)2 VitD. The 1,25(OH)2 VitD-induced decrease in hCLDN16 promoter activity was attenuated in Mg(2+)-depleted HEK 293 cells. In conclusion, 1,25(OH)2 VitD transcriptionally inhibits claudin-16 expression by a mechanism sensitive to CaSR and Mg(2+). This renal effect of 1,25(OH)2 VitD may serve as an adaptive response to the 1,25(OH)2 VitD-induced increase in intestinal Mg(2+) absorption.

High vitamin D status before conception, but not during pregnancy, is inversely associated with maternal gestational diabetes mellitus in guinea pigs

BACKGROUND

Whether there is a dose-dependent effect of maternal dietary cholecalciferol during pregnancy on maternal glucose tolerance is unknown. In addition, circulating osteocalcin is increased by 1,25-dihydroxyvitamin D [1,25(OH)2D] and may improve glucose homeostasis.

OBJECTIVE

This study was designed to test whether dietary cholecalciferol during pregnancy dose-dependently affects maternal glucose tolerance and maternal and neonatal glucose concentrations in relation to plasma osteocalcin and body composition.

METHODS

Female guinea pigs (n = 45; 4 mo old) were randomly assigned to 5 doses of cholecalciferol (0, 0.25, 0.5, 1, or 2 IU/g diet) fed from mating to delivery. Plasma vitamin D metabolites, minerals, and osteocalcin, and blood glucose were measured before mating, at midgestation (day 42), and at day 2 postpartum in sows and in 2-d-old pups. At day 50 of pregnancy (early third trimester), a 3-h oral-glucose-tolerance test (OGTT) (2 g/kg) was conducted. Body composition was measured before mating and at day 2 postpartum in sows and in pups.

RESULTS

A positive dose-response to dietary cholecalciferol was observed for change in maternal plasma 25-hydroxyvitamin D [25(OH)D] through pregnancy (P < 0.0001), with 1,25(OH)2D increasing by 198% in the 1-IU/g group by midgestation vs. a reduction of 43.6% in the 0-IU/g group (P = 0.05). Twenty-four (54.5%) sows had gestational diabetes mellitus (GDM) on the basis of nonfed glucose and 39 (88.6%) had GDM on the basis of 2-h OGTT glucose concentrations. There were no group differences in maternal OGTT or changes in glucose, minerals, osteocalcin concentrations, and body composition. Pre-mating 25(OH)D was inversely related to 3-h area under the curve for blood glucose from the OGTT (r = -0.31, P = 0.05). In guinea pig pups, although both 25(OH)D (P < 0.0001) and 1,25(OH)2D (P < 0.0001) followed a dose-response to maternal diet, glucose, osteocalcin, minerals, and body composition were not altered.

CONCLUSIONS

Dietary vitamin D intake during pregnancy in guinea pigs does not affect the already high rate of GDM, whereas higher prepregnancy vitamin D status appears to be protective.

Acute phase response elicited by experimental bovine diarrhea virus (BVDV) infection is associated with decreased vitamin D and E status of vitamin-replete preruminant calves

Studies in young animals have shown an association between vitamin deficiencies and increased risk of infectious disease; however, there is a paucity of information regarding the effect of acute infection on the vitamin status of the vitamin-replete neonate. To characterize the effects of acute infection on vitamin D and E status of the neonate, 6 vitamin-replete preruminant Holstein bull calves were experimentally infected with bovine viral diarrhea virus (BVDV; strain BVDV2-1373). Six mock-inoculated calves served as controls. Sustained pyrexia, leukopenia, and asynchronous increases in serum haptoglobin and serum amyloid A characterized the response of calves to infection with BVDV. Infection was also associated with increased serum IFN-γ, IL-2, and IL-6 concentrations. During the last 8 d of the 14-d postinoculation period, serum 25-hydroxyvitamin D and α-tocopherol concentrations in infected calves decreased by 51 and 82%, respectively. The observed inverse association between vitamin D and E status and serum amyloid A in infected calves suggests that the infection-induced acute phase response contributed to the reduced vitamin status of these animals. Additional studies are necessary to determine if the negative effect of infection on status are unique to this specific infection model or is representative of preruminant calf's response to acute infection. Studies are also needed to characterize mechanisms underlying infection-related changes in vitamin D and E status and to determine whether additional vitamin D or E supplementation during an acute infection diminishes disease severity and duration in the young animal.

Osteocalcin is higher across pregnancy in Caucasian women with gestational diabetes mellitus

OBJECTIVE

The purpose of this study was to investigate circulating concentrations of osteocalcin, a bone-derived protein, while accounting for 25-hydroxyvitamin D (25(OH)D) throughout pregnancy, and whether early gestation concentrations and changes in osteocalcin predict the subsequent diagnosis of gestational diabetes mellitus (GDM).

METHODS

This was a nested case-control study involving 48 GDM and 48 control pregnant Caucasian women (matched for age, season of conception, pre-pregnancy body mass index and pregnancy length). Maternal serum osteocalcin was measured by enzyme-linked immunosorbent assay and 25(OH)D by chemiluminescence throughout pregnancy (11-13 weeks, 24-28 weeks and predelivery). Differences between groups were compared by mixed model analysis of variance. Predictors of diagnosis of GDM were explored using generalized estimating equation models. Neonatal general health outcomes were also compared between groups.

RESULTS

Serum osteocalcin was higher across pregnancy (p=0.006) in women with GDM vs. controls, whereas serum 25(OH)D was not different (p=0.80). Both biomarkers increased with time across pregnancy (p<0.0001). However, serum osteocalcin during early pregnancy and changes in its concentration from early to mid gestation did not predict the development of GDM. There were no significant differences in anthropometry and APGAR (appearance, pulse, grimace, activity, respiration) scores in neonates of controls and cases.

CONCLUSIONS

Serum osteocalcin is elevated in Caucasian women with GDM throughout pregnancy, but was not predictive of the onset of GDM. Larger trials evaluating the role of osteocalcin and the development of GDM appear warranted.

Detection of 1α,25-dihydroxyvitamin D-regulated miRNAs in zebrafish by whole transcriptome sequencing

The sterol hormone, 1α,25-dihydroxyvitamin D₃ (1α,25(OH)₂D₃), regulates gene expression and messenger RNA (mRNA) concentrations in zebrafish in vivo. Since mRNA concentrations and translation are influenced by micro-RNAs (miRNAs), we examined the influence of 1α,25(OH)₂D₃ on miRNA expression in zebrafish in vivo with whole transcriptome RNA sequencing, searched for miRNA binding sites in 1α,25(OH)₂D₃-sensitive genes, and performed correlation analyses between 1α,25(OH)₂D₃-sensitive miRNAs and mRNAs. In vehicle- and 1α,25(OH)₂D₃-treated, 7-day postfertilization larvae, between 282 and 295 known precursor miRNAs were expressed, and in vehicle- and 1α,25(OH)₂D₃-treated fish, between 83 and 122 novel miRNAs were detected. Following 1α,25(OH)₂D₃ treatment, 31 precursor miRNAs were differentially expressed (p<0.05). The differentially expressed miRNAs are predicted to potentially alter mRNAs for metabolic enzymes, transcription factors, growth factors, and Jak-STAT signaling. We verified the role of a 1α,25(OH)₂D₃-sensitive miRNA, miR125b, by demonstrating alterations in the concentrations of the mRNA of a 1α,25(OH)₂D₃-regulated gene, Cyp24a1, following transfection of renal cells with a miR125b miRNA mimic. Changes in the Cyp24a1 mRNA concentration by the miR125b miRNA mimic were associated with changes in the protein for Cyp24a1. Our data show that 1α,25(OH)₂D₃ regulates miRNA in zebrafish larvae in vivo and could thereby influence vitamin D-sensitive mRNA concentrations.

Changes in Dickkopf-1 (DKK1) and Sclerostin following a Loading Dose of Vitamin D 2 (300,000 IU)

Background. Vitamin D is important for bone health, although high loading doses have been associated with an increase in fracture risk. The mechanisms remain uncertain. Aim. We hypothesize that supraphysiological concentrations of 1,25 (OH)2 vitamin D may inhibit formation by increasing the production of Wnt inhibitors: sclerostin and DKK1. Subjects and Methods. We measured serum sclerostin and DKK1 in 34 patients (21 F, 13 M) aged mean (SD) 61.3 (15.6) years with vitamin D deficiency/insufficiency treated with a loading dose of vitamin D2 (300,000 IU) intramuscularly. Blood samples were taken at baseline and serially up to 3 months. Results. Serum 1,25 (OH)2 vitamin D increased markedly at 3 months (mean (SD) baseline 116 (63), 3 months : 229 (142) pmol/L, P < 0.001). There was a significant correlation between sclerostin and DKK1 at baseline (r = 0.504, P = 0.002) and at 3 months (r = 0.42, P = 0.013). A significant inverse correlation was observed between sclerostin and eGFR at 3 months (r = -0.494, P = 0.007). Sclerostin increased significantly at 3 months (P = 0.033). In a multilinear regression analysis with % change in sclerostin and DKK1 as dependent variable, a positive significant association was observed with % change in 1,25 (OH)2 vitamin D (P = 0.038), independent of changes in PTH and following correction for confounders such as age, gender, BMI, BMD and eGFR. Conclusions. Supraphysiological concentration in 1,25 (OH)2 vitamin D achieved following a loading dose of vitamin D increases sclerostin and may inhibit Wnt signalling. This may have detrimental effects on bone.

The molecular basis for the pharmacokinetics and pharmacodynamics of curcumin and its metabolites in relation to cancer

This review addresses the oncopharmacological properties of curcumin at the molecular level. First, the interactions between curcumin and its molecular targets are addressed on the basis of curcumin's distinct chemical properties, which include H-bond donating and accepting capacity of the β-dicarbonyl moiety and the phenylic hydroxyl groups, H-bond accepting capacity of the methoxy ethers, multivalent metal and nonmetal cation binding properties, high partition coefficient, rotamerization around multiple C-C bonds, and the ability to act as a Michael acceptor. Next, the in vitro chemical stability of curcumin is elaborated in the context of its susceptibility to photochemical and chemical modification and degradation (e.g., alkaline hydrolysis). Specific modification and degradatory pathways are provided, which mainly entail radical-based intermediates, and the in vitro catabolites are identified. The implications of curcumin's (photo)chemical instability are addressed in light of pharmaceutical curcumin preparations, the use of curcumin analogues, and implementation of nanoparticulate drug delivery systems. Furthermore, the pharmacokinetics of curcumin and its most important degradation products are detailed in light of curcumin's poor bioavailability. Particular emphasis is placed on xenobiotic phase I and II metabolism as well as excretion of curcumin in the intestines (first pass), the liver (second pass), and other organs in addition to the pharmacokinetics of curcumin metabolites and their systemic clearance. Lastly, a summary is provided of the clinical pharmacodynamics of curcumin followed by a detailed account of curcumin's direct molecular targets, whereby the phenotypical/biological changes induced in cancer cells upon completion of the curcumin-triggered signaling cascade(s) are addressed in the framework of the hallmarks of cancer. The direct molecular targets include the ErbB family of receptors, protein kinase C, enzymes involved in prostaglandin synthesis, vitamin D receptor, and DNA.

[Fibroblast growth factor 23 mediates the phosphaturic actions of cadmium]

Phosphaturia has been documented following cadmium (Cd) exposure in both humans and experimental animals. Fibroblast growth factor 23 (FGF23) serves as an essential phosphate homeostasis pathway in the bone-kidney axis. In the present study, we investigated the effects of Cd on phosphate (Pi) homeostasis in mice. Following Cd injection into C57BL/6J mice, plasma FGF23 concentration significantly increased. The urinary Pi excretion level was significantly higher in the Cd-injected C57BL/6J mice than in the control group. Plasma Pi concentration decreased only slightly in the Cd-injected mice compared with the control group. No changes were observed in the concentration of the plasma parathyroid hormone and 1,25-dihydroxy vitamin D(3) in both groups of mice. We observed a decrease in phosphate transport activity and also a decrease in the expression level of renal phosphate transporter Npt2c, but not that of Npt2a. Furthermore, we examined the effect of Cd on Npt2c in Npt2a-knockout (KO) mice, which expresses Npt2c as a major NaPi cotransporter. Injecting Cd to Npt2aKO mice induced a significant increase in plasma FGF23 concentration and urinary Pi excretion level. Furthermore, we observed decreases in phosphate transport activity and renal Npt2c expression level in the Cd-injected Npt2a KO mice. The present study suggests that hypophosphatemia induced by Cd may be closely associated with FGF23.