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Background: Calcitriol has the potential to counteract fibrotic diseases beyond its classical action of maintaining calcium and bone metabolism; however, its functional mechanism remains unknown. Autophagy-related gene 16-like 1 (Atg16l1) is one of the genes related to autophagy and is involved in protecting against fibrotic diseases. The present study aimed to explore the contribution of autophagy to the inhibition of calcitriol-induced hepatic fibrosis, as well as its potential molecular mechanism., Methods: Carbon tetrachloride (Ccl 4 )-treated mice were established as hepatic fibrosis models and received calcitriol treatment for 6 weeks. Quantification of Sirius red staining and measurement of key fibrotic markers (collagen-1 and α-SMA) was performed to detect hepatic fibrosis. Chloroquine (CQ) treatment was used to observe autophagic flux, and 3-methyladenine (3-MA) was used to inhibit autophagy. Furthermore, the effects of calcitriol on transforming growth factor β1 (TGFβ1)-stimulated primary hepatic stellate cells (HSCs) were detected. Downregulation of Atg16l1 or vitamin D receptor (VDR) in LX-2 cells was used to explore the mechanism of action of calcitriol in fibrosis and autophagy. Additionally, the electrophoretic mobility shift assay (EMSA) was used to investigate the interactions between VDR and ATG16L1., Results: Calcitriol increased the expression of VDR and ATG16L1, enhanced autophagy and attenuated hepatic fibrosis. 3-MA treatment and VDR silencing abolished the protective effects of calcitriol against fibrosis. Calcitriol-induced anti-fibrosis effects were blocked by ATG16L1 suppression. Furthermore, VDR bound to the ATG16L1 promoter and downregulation of VDR decreased the expression of ATG16L1 in LX-2 cells., Conclusion: Calcitriol mitigates hepatic fibrosis partly through ATG16L1-mediated autophagy., Competing Interests: Declaration of competing interest The authors declare no conflict of interests., (Copyright © 2024 Southern Society for Clinical Investigation. Published by Elsevier Inc. All rights reserved.)

Bile acids (BAs) are known to be important regulators of intestinal motility and epithelial fluid and electrolyte transport. Over the past two decades, significant advances in identifying and characterizing the receptors, transporters, and ion channels targeted by BAs have led to exciting new insights into the molecular mechanisms involved in these processes. Our appreciation of BAs, their receptors, and BA-modulated ion channels as potential targets for the development of new approaches to treat intestinal motility and transport disorders is increasing. In the current review, we aim to summarize recent advances in our knowledge of the different BA receptors and BA-modulated ion channels present in the gastrointestinal system. We discuss how they regulate motility and epithelial transport, their roles in pathogenesis, and their therapeutic potential in a range of gastrointestinal diseases.

Introduction: Secondary hyperparathyroidism (SHPT) represents a complication of chronic kidney disease (CKD). Vitamin D system is altered since early CKD, and vitamin D deficiency is an established trigger of SHPT. Although untreated SHPT may degenerate into tertiary hyperparathyroidism with detrimental consequences in advanced CKD, best treatments for counteracting SHPT from stage 3 CKD are still debated. Enthusiasm on prescription of vitamin D receptor activators (VDRA) in non-dialysis renal patients, has been mitigated by the risk of low bone turnover and positive calcium-phosphate balance. Nutritional vitamin D is now suggested as first-line therapy to treat SHPT with low 25(OH)D insufficiency. However, no high-grade evidence supports the best choice between ergocalciferol, cholecalciferol, and calcifediol (in its immediate or extended-release formulation). Areas covered: The review discusses available data on safety and efficacy of nutritional vitamin D, VDRA and nutritional therapy in replenishing 25(OH)D deficiency and counteracting SHPT in non-dialysis CKD patients. Expert opinion: Best treatment for low 25(OH)D and SHPT remains unknown, due to incomplete understanding of the best homeostatic, as mutable, adaptation of mineral metabolism to CKD progression. Nutritional vitamin D and nutritional therapy appear safest interventions, whenever contextualized with single-patient characteristics. VDRA should be restricted to uncontrolled SHPT by first-line therapy.

Introduction: Background: the biological activity of vitamin D depends on the activity of its receptor or VDR. On the other hand, the activity of this receptor is influenced by its state of methylation. The objective of this study was to verify if the BsmI polymorphism of the VDR gene influences its methylation profile in adolescents. Secondly, it was to verify if the status of some metabolic factors (oxidative stress, inflammation, lipid profile, and glycemia) in the serum, and gender-adjusted vitamin D levels are independent factors with an influence on the VDR methylation profile. Methods and results: the study included 198 adolescents of both sexes, aged 15-19 years, who underwent testing for VDR gene methylation polymorphisms, serum vitamin D levels, and metabolic, oxidative stress, and systemic inflammation markers. It was observed that the BB genotype was less methylated than the other groups (26.1 % versus 30.3 %, and 29.3 % for Bb and bb, respectively), although without statistical differences between them. The odds ratio indicated a protection of 13 % (partially methylated) for vitamin D status, while alpha glycols increased the risk ratio (of being partially methylated) by 3 %. MDA was protective at a 28 % chance of risk that adolescents with higher levels of lipid peroxidation would be hypomethylated. Conclusion: we conclude that the methylation profile of the VDR gene is not influenced by the different BsmI polymorphism genotypes, and that serum vitamin D and serum markers of oxidative stress and inflammation can modulate this profile.

Mounting clinical evidence has revealed that the vitamin D receptor (VDR) is associated with cholestatic liver injury, although the functions of VDR in this condition remain largely unexplored. Here, we investigated the effects of VDR activation on bile duct ligation (BDL) mice, and the underlying mechanisms were further investigated. A low-calcemic VDR agonist, paricalcitol (PAL, 200 ng/kg), was intraperitoneally injected into BDL mice every other day for 5 days or 28 days. Liver histology, liver function indicators, cholangiocyte proliferation, fibrosis scores, and inflammation were evaluated. Mice treated with PAL were rescued from the decreased survival rate induced by BDL and liver damage was reduced. Mechanistically, PAL promoted cholangiocyte proliferation, which was likely conducive to proliferating bile duct maturation and increased branching of bile ducts. PAL treatment also increased the expression of Yes-associated protein (YAP) and its target protein epithelial cell adhesion molecule (EpCam) and decreased the level of inactive cytoplasmic phosphorylated YAP. YAP knockdown abrogated PAL-induced primary bile duct epithelial cell proliferation, confirmed with YAP inhibitor administration. In addition, BDL-induced liver fibrosis and inflammatory cell infiltration were reduced by PAL treatment at both day 5 and day 28 post-BDL. In conclusion, VDR activation mitigates cholestatic liver injury by promoting adaptive bile duct remodeling through cholangiocytic YAP upregulation. Because PAL is an approved clinical drug, it may be useful for treatment of cholestatic liver disease. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd., (© 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.)

Secondary hyperparathyroidism (SHPT) in uremic patients is characterized by parathyroid gland (PTG) hyperplasia and parathyroid hormone (PTH) elevation. Previously, we demonstrated that NF-κB activation contributed to parathyroid cell proliferation in rats with chronic kidney disease. Although vitamin D inhibits inflammation and ameliorates SHPT, the contribution of vitamin D deficiency to SHPT via local NF-κB activation remains to be clarified. PTGs collected from 10 uremic patients with advanced SHPT were used to test the expressions of vitamin D receptor (VDR), NF-κB, and proliferating cell nuclear antigen (PCNA). Freshly excised PTG tissues were incubated for 24 hours in vitro with VDR activator (VDRA) calcitriol or NF-κB inhibitor pyrrolidine thiocarbamate (PDTC). Chromatin immunoprecipitation (ChIP) and luciferase reporter assays were performed to investigate the regulation of PTH transcription by NF-κB. We found higher levels of activated NF-κB and lower expression of VDR in nodular hyperplastic PTGs than in diffuse hyperplasia. In cultured PTG tissues, treatment with VDRA or PDTC inhibited NF-κB activation and PCNA expression, and downregulated preproPTH mRNA and intact PTH levels. ChIP assays demonstrated the presence of NF-κB binding sites in PTH promoter. Furthermore, in luciferase reporter assays, addition of exogenous p65 significantly increased PTH luciferase activity by 2.4-fold (P < 0.01), while mutation of NF-κB binding site at position -908 of the PTH promoter suppressed p65-induced PTH reporter activity (P < 0.01). In summary, local NF-κB activation contributes to SHPT and mediates the transcriptional activation of PTH directly in uremic patients. Vitamin D deficiency may be involved in SHPT via the activation of NF-κB pathway., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Endocrine Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Lead is a ubiquitous heavy metal toxin of significant public health concern. Every individual varies in their response to lead's toxic effects due to underlying genetic variations in lead metabolizing enzymes or proteins distributed in the population. Earlier studies, including our lab, have attributed the influence of ALAD (δ-Aminolevulinate dehydratase) polymorphism on blood lead retention and ALAD activity. The present study aimed to investigate the influence of VDR (Vitamin D receptor) and HFE (Hemochromatosis) polymorphisms in modulating blood lead levels (BLLs) of occupationally exposed workers. 164 lead-exposed subjects involved in lead alloy manufacturing and battery breaking and recycling processes and 160 unexposed controls with BLLs below 10 µg/dL recruited in the study. Blood lead levels, along with a battery of biochemical assays and genotyping, were performed. Regression analysis revealed a negative influence of BLLs on ALAD activity ( p < 0.0001) and a positive influence on smokeless tobacco use ( p < 0.001) in lead-exposed subjects. A predicted haplotype of the three VDR polymorphisms computed from genotyping data revealed that T-A-A haplotype increased the BLLs by 0.93 units ( p ≤ 0.05) and C-C-A haplotype decreased the BLLs by 7.25 units ( p ≤ 0.05). Further analysis revealed that the wild-type CC genotype of HFE H63D presented a higher median BLL, indicating that variant C allele may have a role in increasing the concentration of lead. Hence, the polymorphism of genes associated with lead metabolism might aid in predicting genetic predisposition to lead and its associated effects.

Epidemiologic studies have clearly demonstrated the correlation existing between Vitamin D (Vit. D) deficiency and increased risk of developing cardiovascular disease, suggesting that it might have a protective role in this clinical setting. Although many experimental studies have investigated the molecular mechanisms by which Vit. D might exert these effects, its potential role in protecting against athero-thrombosis is still partially unknown. We have investigated whether Vit. D might exert anti athero-thombotic effects by preventing expression of adhesion molecules (CAMs) and Tissue Factor (TF), molecules involved in atherothrombotic pathophysiology, in oxLDL stimulated endothelial cells (HUVEC). Moreover, we have investigated whether Vit. D effects might be due to the NF-kB modulation. HUVEC cultivated in medium enriched with Vit. D (10 nM) were stimulated with oxLDL (50 μg/ml). TF gene (RT-PCR), protein (Western blot), surface expression (FACS) and procoagulant activity (FXa generation assay) were measured. Similarly, CAMs gene (RT-PCR), surface expression (FACS) and soluble values (ELISA) were measured. NF-kB translocation was also investigated. Vit. D significantly reduced TF gene as well protein expression and procoagulant activity in oxLDL-treated HUVEC. Similar effects were observed for CAMs. These effects were associated with Vit. D modulation of NF-κB pathway. This study, although in vitro, indicate that Vit. D has protective effect on endothelial cells by inhibiting expression of TF and CAMs, proteins involved in atherothrombotic pathophysiology. Further studies will be necessary to translate these findings to a clinical scenario to better define the potential therapeutical role of Vit. D supplementation in the management of cardiovascular disease in patients with Vit. D deficiency., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Background and Purpose: Immunosuppression is the predominant cause of mortality for sepsis because of failure to eradicate pathogens. No effective and specific drugs capable of reversing immunosuppression are clinically available. Evidences implicate the involvement of the vitamin D receptor (NR1I1) in sepsis-induced immunosuppression. The anti-malarial artesunate was investigated to determine action on sepsis-induced immunosuppression., Experimental Approach: The effect of artesunate on sepsis-induced immunosuppression was investigated in mice and human and mice cell lines. Bioinformatics predicted vitamin D receptor as a candidate target for artesunate, which was then identified using PCR and immunoblotting. Vdr, Atg16l1 and NF-κB p65 were modified to investigate artesunate 's effect on pro-inflammatory cytokines release, bacterial clearance and autophagy activities in sepsis-induced immunosuppression., Key Results: Artesunate significantly reduced the mortality of caecal ligation and puncture (CLP)-induced sepsis immunosuppression mice challenged with Pseudomonas aeruginosa and enhanced pro-inflammatory cytokine release and bacterial clearance to reverse sepsis-induced immunosuppression in vivo and in vitro. Mechanistically, artesunate interacted with vitamin D receptor, inhibiting its nuclear translocation, which influenced ATG16L1 transcription and subsequent autophagy activity. Artesunate inhibited the physical interaction between vitamin D receptor and NF-κB p65 in LPS-tolerant macrophages and then promoted the nuclear translocation of NF-κB p65, which activated the transcription of NF-κB p65 target genes such as pro-inflammatory cytokines., Conclusion and Implications: Our findings provide evidence that artesunate interacted with vitamin D receptor to reverse sepsis-induced immunosuppression in an autophagy and NF-κB-dependent manner, highlighting a novel approach for sepsis treatment and drug repurposing of artesunate has a bidirectional immunomodulator., (© 2020 The British Pharmacological Society.)

Purpose: In this study, we aimed to investigate the effect of paricalcitol and calcitriol usage on vitamin D receptor (VDR) contents of CD8+ , CD4+ lymphocytes and monocytes in stage 5d chronic kidney disease (CKD) patients., Methods: Thirty-six hemodialysis patients older than 18 years of age and 19 healthy controls (group HC) without any known acute or chronic diseases were included in the study. The group of patients undergoing scheduled hemodialysis comprised three subgroups: group CL: patients on calcitriol (n: 10), group PC: patients on paricalcitol (n: 13), and group NT: patients not taking any vitamin D or VDR activating medications (n: 13). CD8+/VDR, CD4+/VDR and MONO/VDR values were representing the ratio of VDR representing cells among related cell group. On the other hand, values of CD8+/MFI, CD4+/MFI and MONO/MFI have shown the total amount of cellular VDR content per cell which has been given as of mean fluorescence intensity in the flow cytometric process. Main CKD mineral bone disorder parameters such as a hemogram, serum BUN, creatinine, albumin, Ca, iP, iPTH, 25(OH)D 3 levels were also measured., Results: Average VDR contents in CD8+, CD4+ and monocytes were not different among three patient groups on hemodialysis. But in all hemodialysis subgroups, CD8+/VDR, CD4+/VDR, MONO/VDR, CD8+/MFI, CD4+/MFI and MONO/MFI levels were found to be higher compared with the healthy control subjects (p < 0.001). Among hemodialysis groups, no significant CD8+/VDR, CD4+/VDR, and MONO/VDR content differences were found with regard to the type of VDR activator agent used. There was no difference in serum levels of 25(OH)D 3 and CRP among groups participating in the study., Conclusion: There was no difference between CD8+/VDR, CD4+/VDR, and MONO/VDR levels in hemodialysis patients using calcitriol or paricalcitol, suggesting that both treatment agents may have a similar effect on VDR contents in lymphocytes and monocytes in that patient population. But in all hemodialysis subgroups, CD8+/VDR, CD4+/VDR, and MONO/VDR levels were found to be higher compared with the healthy control subjects, suggesting an overexpression of VDR through a non CRP and/or 25(OH)D 3 dependent mechanism.

Continuing our studies aimed at A-ring modified vitamin D compounds, we designed novel 19-norcalcitriol derivatives bearing at C-2 pegylated chains of different lengths. The terminal fragments of these substituents contain hydroxyls or moieties possessing nitrogen and/or sulfur atoms capable of transition metal ions complexation. Also, two conjugate-type platinum(II) complexes of 19-norcalcitriol were obtained in which l-methionine served as chelating moiety. The convergent synthesis of the target 19-norcalcitriol analogs involved several steps with the crucial one being condensation of A-ring phosphine oxide and the known Grundmann ketone by Wittig-Horner reaction. Further elaboration of the 2-alkylidene substituent provided all final compounds which were then tested to determine their affinity for the vitamin D receptor and cytotoxic activity., Competing Interests: Declaration of Competing Interest The authors declared that there is no conflict of interest., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Background/aim: The combination of paclitaxel and carboplatin is the standard chemotherapy for ovarian cancer. Previous studies have implied that vitamin D (1,25-D3) may have growth inhibitory effects in ovarian cancer. This study aimed to investigate the effect of paclitaxel, carboplatin and 1,25-D3 on the growth of ovarian cancer cells in vitro, based on the hypothesis that 1,25-D3 might potentiate the effect of paclitaxel and/or carboplatin., Materials and Methods: Three non-commercial ovarian carcinoma cell lines UT-OV-1(mucinous), UT-OV-3B (serous) and UT-OV-4 (endometrioid) were exposed to different concentrations of 1,25-D3, paclitaxel and carboplatin, respectively. The cell viability was measured using a Crystal violet assay kit. The cellular vitamin D receptor (VDR) mRNA levels were measured by qRT-PCR using the LightCycler equipment., Results: The growth-inhibitory effect of the combination of paclitaxel and carboplatin was 56% in UT-OV-1, 33% in UT-OV-3B and 47% in UT-OV-4 cells. Single 1,25-D3 (10 μM) inhibited the growth of UT-OV-3B and UT-OV-4 by 23% and 28%, respectively, whereas no effect was seen in UT-OV-1 cells. These results are in line with the finding that the expression of VDR was high in UT-OV-3B and UT-OV-4, but very low in UT-OV-1. The combination of 1,25-D3, paclitaxel and carboplatin resulted in 61%, 46% and 58% growth reduction in UT-OV-1, UT-OV-3B and UT-OV-4 cells, respectively. The additive effect of 1,25-D3 was 21% in UT-OV-4, 20% in UT-OV-3B and 12% in UT-OV-1 cell line., Conclusion: The results imply that combining 1,25-D3 with paclitaxel and carboplatin may potentiate their growth inhibitory effect on ovarian cancer cells with high VDR expression., (Copyright© 2020, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Introduction: Primary sclerosing cholangitis (PSC) is a cholestatic liver disorder that is frequently associated with ulcerative colitis (UC). Patients with PSC and UC (PSC-UC) have a higher risk of colorectal neoplasia compared with patients with UC. The oncogenic properties of microRNA-346 (miR-346) have been recently reported. We investigated the expression of miR-346 and its 2 target genes, the receptor of vitamin D (VDR), and the tumor necrosis factor-α (TNF-α), which are known to modulate carcinogenesis., Methods: Ascending and sigmoid colon biopsies were obtained from patients with PSC, PSC and UC (PSC-UC), UC, and healthy controls (n = 10 in each group). Expressions of VDR, TNF-α, 18S RNA, p27, miR-346, and reference microRNA, miR-191, were evaluated by real-time PCR using human TaqMan Gene Expression and TaqMan MicroRNA Assays. Functional studies with miR-346 mimic and inhibitor were conducted in HepG2 and Caco-2 cells. The effect of ursodeoxycholic acid on miR-346 expression was examined in Caco-2 cells., Results: An increased expression of miR-346 in the ascending colon of PSC-UC was observed (P < 0.001 vs all groups). In patients with UC, an exceptionally low colonic expression of miRNA-346 was accompanied by the extensive upregulation of VDR and TNF-α genes. A functional in vitro analysis demonstrated that inhibition of miR-346 resulted in the upregulation of VDR and TNF-α, whereas the induction of miR-346 activity suppressed VDR, TNF-α, and p27., Discussion: The upregulation of miRNA-346 in the colon of patients with PSC may be responsible for the disturbance of VDR and TNF-α signaling pathway, which could result in an inadequate suppression of neoplasia.

Some epidemiological studies suggested caffeine consumption as the cause for bone mineral density loss. Certain genes involved in this process are regulated by vitamin D receptor (VDR). Therefore, we investigated if caffeine can affect inducible expression of VDR-regulated genes, some of them being involved in bone mineralization process. By employing reporter gene assay, polymerase chain reaction, and western blotting, we monitored the VDR activity and expression in cell cultures of intestinal (LS180), osteosarcoma (HOS), and normal human osteoblasts in vitro. While caffeine stimulated calcitriol-inducible VDR-dependent nanoluciferase activity in stable reporter cell line IZ-VDRE (derived from LS180), it rather modulated mRNA levels of target genes, like CYP24A1, BGLAP, SPP1, and TNSF11 in LS180 and HOS cells. However, caffeine significantly decreased calcitriol-inducible CYP24A1, TNSF11, and SPP1 transcripts in osteoblasts. This decrease had non-linear U-shaped profile. Our in vitro data demonstrate biphasic action of caffeine on the expression of certain calcitriol-inducible VDR-regulated genes in normal human osteoblasts.

Background: Microparticles (MPs) are biomarkers and mediators of disease through their expression of surface receptors, reflecting activation or stress in their parent cells. Endothelial markers, ICAM-1 and VCAM-1, are implicated in atherosclerosis and associated with cardiovascular risk. Chronic kidney disease (CKD) patients have endothelial dysfunction and high levels of endothelial derived MPs. Vitamin D treatment has been reported to ameliorate endothelial function in CKD patients. We aimed to examine cell specific MP profiles and concentrations of MPs expressing the atherosclerotic markers ICAM-1 and VCAM-1 after treatment with paricalcitol in patients with CKD stage 3-4., Methods: Sub-study of the previously reported SOLID trial where 36 patients were randomly assigned to placebo, 1 or 2 μg paricalcitol, for 12 weeks. MPs were measured by flow cytometry after labelling with antibodies against endothelial (CD62E), platelet (CD62P, CD41, CD154) leukocyte (CD45) and vascular (CD54, CD106) markers., Results: Patients had a mean age of 65 years with a mean eGFR of 40 mL/min/1.73m 2 . Concentrations of ICAM-1 positive MPs were significantly reduced by treatment (repeated measures ANOVA p = 0.04). Repeated measures MANOVA of concentrations of endothelial, platelet and leukocyte MPs showed sustained levels in the 2 μg treatment group (p = 0.85) but a decline in the 1 μg (p = 0.04) and placebo groups (p = 0.005)., Conclusions: Treatment with paricalcitol reduces concentrations of ICAM-1 positive MPs. This is accompanied by sustained concentrations of all cell specific MPs in the 2 μg group, and decreasing concentrations in the other groups, possibly due to a more healthy and reactive endothelium with paricalcitol treatment.

Here we review tumoricidal efficacy of Vitamin D analogues in glioblastoma multiforme (GBM) and potential synergisms with retinoic acid and temozolomide based on epidemiological and cellular studies. Epidemiological data suggest that winter birth is associated with higher risk of GBM, and GBM debulking in the winter enhanced mortality, which may relate with lower exposure to sunlight essential to convert cholecalciferol to Vitamin D. Comparative studies on blood bank specimens revealed that higher prediagnosis levels of calcidiol are associated with lower risk of GBM in elderly men. Supplemental Vitamin D reduced mortality in GBM patients in comparison to nonusers. Expression of Vitamin D Receptor is associated with a good prognosis in GBM. Conversely, Vitamin D increases glial tumor synthesis of neutrophins NGF and NT-3, the low affinity neurotrophin receptor p75NTR, IL-6 and VEGF, which may enhance glioma growth. Antitumor synergisms between temozolomide and Vitamin D and Vitamin D with Vitamin A derivatives were observed. Hence, we hypothesize that Calcitriol + ATRA (All-Trans Retinoic Acid) + Temozolomide - CAT combination might be a safer approach to benefit from Vitamin D in the management of high-grade glial tumors. Adding acetazolomide to this protocol may reduce the risk of pseudotumor cerebri, as both Vitamin D and Vitamin A excess may cause intracranial hypertension; this approach may provide further benefit as acetazolomide also exhibits anticancer activity.

Many in vitro studies support the general idea that vitamin D plays a protective role against cancer. Increased doses of vitamin D dietary supplements have been widely used for the potential anticancer benefits of vitamin D. However, despite substantial epidemiological research, there are no clear conclusive data to support the use of vitamin D as a cancer preventive or treatment agent. In the, herein, reported study, we checked the effects of 1,25-dihydroxyvitamin D 3 concentrations on the expression level of the vitamin D receptor (VDR) and cell cycle-related proteins CDKN1A (p21) and CDK1 in pancreatic cells and Panc-1 pancreatic cancer (PC) cells. We found that VDR, CDKN1A, and CDK1 were upregulated by an increase in 1,25-dihydroxyvitamin D 3 concentration in normal pancreatic cells but not in the advanced cancer cell line Panc-1 from poorly differentiated metastatic PC cells. A further increase in 1,25-dihydroxyvitamin D 3 concentration above the physiological range significantly downregulated the expression of VDR, indicating that VDR is modulated by VDR levels to maintain normal functioning during dramatic variations in vitamin D concentration. By increasing the level of cell cycle inhibitory and promoting proteins p21 and CDK1, vitamin D theoretically has both preventive and promoting effects on pancreatic cell division.

Background: It has been suggested that genetic variation within candidate pharmacogenes contributes to the differences in drug safety and efficacy as well as risk of adverse drug reactions among different ethnic groups. Illustrating the polymorphic distribution of Very Important Pharmacogenes (VIPs) in various ethnic groups will contribute to the development of personalized medicine for those populations., Objective: The present study aimed to identify the polymorphic distribution of VIPs in the Circassian subpopulation of Jordan and compare their allele frequencies with those of other populations., Methods: A total of 130 healthy and unrelated Circassian adults from Jordan were randomly recruited and genotyped for eleven VIP variants within the thiopurine S-methyltransferase (TPMT), ATP-binding cassette, sub-family B, member 1 (ABCB1), and vitamin D receptor (VDR) genes via Sequenom's MassARRAY® genotyping platform (iPLEX GOLD)., Results: Our data on the allelic frequencies of the investigated VIP variants were compared to those of 18 other populations, comprising 11 HapMap populations, 6 Exome Aggregation Consortium populations, and the Chechen- Jordanian population from Jordan. Circassian-Jordanians were found to most resemble the African, Chechen- Jordanian, European (Finnish), European (non-Finnish), and South-Asian populations., Conclusion: Circassians from Jordan significantly differ from other populations in terms of the allelic frequencies of selected VIP variants. The present findings constitute the first set of pharmacogenetic data for Circassian population from Jordan, providing a basis for safe drug administration that may be useful in diagnosing and treating diseases in this ethnic group., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Importance: Patients with chronic kidney disease have impaired vitamin D activation and elevated cardiovascular risk. Observational studies in patients treated with hemodialysis showed that the use of active vitamin D sterols was associated with lower risk of all-cause mortality, regardless of parathyroid hormone levels., Objective: To determine whether vitamin D receptor activators reduce cardiovascular events and mortality in patients without secondary hyperparathyroidism undergoing hemodialysis., Design, Setting, and Participants: Randomized, open-label, blinded end point multicenter study of 1289 patients in 207 dialysis centers in Japan. The study included 976 patients receiving maintenance hemodialysis with serum intact parathyroid hormone levels less than or equal to 180 pg/mL. The first and last participants were enrolled on August 18, 2008, and January 26, 2011, respectively. The final date of follow-up was April 4, 2015., Interventions: Treatment with 0.5 μg of oral alfacalcidol per day (intervention group; n = 495) vs treatment without vitamin D receptor activators (control group; n = 481)., Main Outcomes and Measures: The primary outcome was a composite measure of fatal and nonfatal cardiovascular events, including myocardial infarctions, hospitalizations for congestive heart failure, stroke, aortic dissection/rupture, amputation of lower limb due to ischemia, and cardiac sudden death; coronary revascularization; and leg artery revascularization during 48 months of follow-up. The secondary outcome was all-cause death., Results: Among 976 patients who were randomized from 108 dialysis centers, 964 patients were included in the intention-to-treat analysis (median age, 65 years; 386 women [40.0%]), and 944 (97.9%) completed the trial. During follow-up (median, 4.0 years), the primary composite outcome of cardiovascular events occurred in 103 of 488 patients (21.1%) in the intervention group and 85 of 476 patients (17.9%) in the control group (absolute difference, 3.25% [95% CI, -1.75% to 8.24%]; hazard ratio, 1.25 [95% CI, 0.94-1.67]; P = .13). There was no significant difference in the secondary outcome of all-cause mortality between the groups (18.2% vs 16.8%, respectively; hazard ratio, 1.12 [95% CI, 0.83-1.52]; P = .46). Of the 488 participants in the intervention group, 199 (40.8%) experienced serious adverse events that were classified as cardiovascular, 64 (13.1%) experienced adverse events classified as infection, and 22 (4.5%) experienced malignancy-related serious adverse events. Of 476 participants in the control group, 191 (40.1%) experienced cardiovascular-related serious adverse events, 63 (13.2%) experienced infection-related serious adverse events, and 21 (4.4%) experienced malignancy-related adverse events., Conclusions and Relevance: Among patients without secondary hyperparathyroidism undergoing maintenance hemodialysis, oral alfacalcidol compared with usual care did not reduce the risk of a composite measure of select cardiovascular events. These findings do not support the use of vitamin D receptor activators for patients such as these., Trial Registration: UMIN-CTR Identifier: UMIN000001194.

Stanozolol (ST) is a synthetic androgen with high anabolic potential. Although it is known that androgens play a positive role in bone metabolism, ST action on bone cells has not been sufficiently tested to support its clinical use for bone augmentation procedures., Objective: This study aimed to assess the effects of ST on osteogenic activity and gene expression in SaOS-2 cells., Material and Methods: SaOS-2 deposition of mineralizing matrix in response to increasing doses of ST (0-1000 nM) was evaluated through Alizarin Red S and Calcein Green staining techniques at 6, 12 and 24 days. Gene expression of runt-related transcription factor 2 (RUNX2), vitamin D receptor (VDR), osteopontin (SPP1) and osteonectin (ON) was analyzed by RT-PCR., Results: ST significantly influenced SaOS-2 osteogenic activity: stainings showed the presence of rounded calcified nodules, which increased both in number and in size over time and depending on ST dose. RT-PCR highlighted ST modulation of genes related to osteogenic differentiation., Conclusions: This study provided encouraging results, showing ST promoted the osteogenic commitment of SaOS-2 cells. Further studies are required to validate these data in primary osteoblasts and to investigate ST molecular pathway of action.

Purpose of Review: The current review is to summarize the recent progress of vitamin D/vitamin D receptor (VDR) and microbiome in intestinal homeostasis, airway function, and other organs., Recent Findings: Microbiome is considered as a newly discovered human organ. It is critical in the synthesis of vitamins and harvest of otherwise inaccessible nutrients, metabolism of xenobiotics, body fat storage, renewal of gut epithelial cells, and mature of immune system. Vitamin D and VDR are known to regulate microbiome in health and disease. We will focus on the recent findings published in 12-18 months and discuss the vitamin D supplement and its effects on microbiome, intestinal homeostasis, airway function, and metabolism. We will emphasize the tissue specificity and genetic factor of VDR and microbiome., Summary: The findings in dietary vitamin D, VDR, and microbiome with personalized genetic information will be implicated for optimal prevention and treatment of chronic diseases.

In general, chronotherapy is desirable for a more effective and/or safe dosage regimen. In this study, a daily rhythm of skin vitamin D receptor (VDR) and chronotherapeutic profiles of maxacalcitol, a vitamin D analogue, were evaluated using mice with skin inflammation induced by topical 12-O-tetradecanoylphorbol-13-acetate (TPA). This study showed that skin nuclear VDR expression in TPA-treated mice has a daily rhythm with the peak at the middle of active period. The effects of maxacalcitol were greater after dosing during early to middle of active period than those after dosing during early to middle of inactive period. These data suggest that chronotherapeutic profiles of maxacalcitol partly depend on the daily rhythm of skin nuclear VDR in TPA-treated mice. Because TPA-treated mice are considered as one of animal models of psoriasis, these animal data might be helpful for establishing chronotherapeutic approach of maxacalcitol in clinical practice.

The vitamin D receptor (VDR) is a nuclear receptor that mediates the biological action of the active form of vitamin D, 1α,25-dihydroxyvitamin D₃ [1,25(OH)₂D₃], and regulates calcium and bone metabolism. Lithocholic acid (LCA), which is a secondary bile acid produced by intestinal bacteria, acts as an additional physiological VDR ligand. Despite recent progress, however, the physiological function of the LCA−VDR axis remains unclear. In this study, in order to elucidate the differences in VDR action induced by 1,25(OH)₂D₃ and LCA, we compared their effect on the VDR target gene induction in the intestine of mice. While the oral administration of 1,25(OH)₂D₃ induced the Cyp24a1 expression effectively in the duodenum and jejunum, the LCA increased target gene expression in the ileum as effectively as 1,25(OH)₂D₃. 1,25(OH)₂D₃, but not LCA, increased the expression of the calcium transporter gene Trpv6 in the upper intestine, and increased the plasma calcium levels. Although LCA could induce an ileal Cyp24a1 expression as well as 1,25(OH)₂D₃, the oral LCA administration was not effective in the VDR target gene induction in the kidney. No effect of LCA on the ileal Cyp24a1 expression was observed in the VDR-null mice. Thus, the results indicate that LCA is a selective VDR ligand acting in the lower intestine, particularly the ileum. LCA may be a signaling molecule, which links intestinal bacteria and host VDR function.

Objectives: The aim of this study was to investigate the possible correlation between vitamin D receptor (VDR) gene polymorphism and susceptibility to chronic kidney disease (CKD) and periodontal disease., Material and Methods: This study analysed 345 participants, who were all 79 years of age. Kidney function levels were determined based on the estimated glomerular filtration rate (eGFR; non-reduced function: ≥60 and reduced function: <60 ml min -1  1.73 m -2 ). VDR TaqI genotyping was also studied. We calculated the periodontal inflamed surface area (PISA). After classifying participants into quartile groups according to eGFR or PISA values, the subjects were then split into two groups (highest quartile versus the other three groups combined). Multiple logistic regression analysis was performed to evaluate the odds ratios between the eGFR and VDR TaqI genotype with the different PISA groups. The eGFR was set as the dependent variable while the VDR TaqI genotype, HbA1C, gender, smoking habits and body mass index were defined as independent variables., Results: A significant association was observed between the VDR TaqI genotype and eGFR in the PISA high group (odds ratio = 3.97, p = .027)., Conclusion: Study results suggest that VDR TaqI genotype might be associated with CKD during inflammatory conditions caused by periodontal disease., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Anemia is a common complication of chronic kidney disease (CKD). There are various causes of renal anemia such as decreased production of erythropoietin, resistance to erythropoietin, shortened survival of red blood cells, and bone marrow fibrosis. Secondary hyperparathyroidism (SHPT) is a less recognized, but potentially significant cause of renal anemia in CKD patients. Parathyroid hormone (PTH) has been regarded as a uremic toxin that has multiple adverse effects, and its elevated levels have been associated with renal anemia in hemodialysis patients. Moreover, recent clinical studies have shown that the treatment of SHPT using either vitamin D receptor activators, calcimimetics, or parathyroidectomy leads to improvement of anemia, supporting the role of PTH in renal anemia. Emerging data have also indicated the involvement of bone-derived fibroblast growth factor 23 in renal anemia. This review summarizes recent insights into the role of PTH in renal anemia and discusses the importance of treating SHPT in improving the control of renal anemia in hemodialysis patients., (© 2018 The Authors. Therapeutic Apheresis and Dialysis published by John Wiley & Sons Australia, Ltd on behalf of International Society for Apheresis, Japanese Society for Apheresis, and Japanese Society for Dialysis Therapy.)

The vitamin D 3 receptor (VDR), which belongs to the nuclear-receptor superfamily, is a potential molecular target for anticancer-drug discovery. In this study, a series of nonsteroidal vitamin D mimics with phenyl-pyrrolyl pentane skeletons with therapeutic potentials in cancer treatment were synthesized. Among them, 11b and 11g were identified as the most effective agents in reducing the viability of four cancer-cell lines, particularly those of breast-cancer cells, with IC 50 values in the submicromolar-concentration range. In addition, 11b and 11g possessed VDR-binding affinities and displayed significant partial VDR-agonistic activities determined by dual-luciferase-reporter assays and human-leukemia-cell-line (HL-60)-differentiation assays. Furthermore, 11b and 11g inhibited tumor growth in an orthotopic breast-tumor model via inhibition of cell proliferation and induction of cell apoptosis. More importantly, 11b and 11g exhibited favorable pharmacokinetic behavior in vivo and did not increase serum calcium levels or cause any other apparent side effects. In summary, 11b and 11g act as novel VDR modulators and may be promising candidates for cancer chemotherapy.

Background and Purpose: The aim of this study was to investigate the expression levels of vitamin D receptor (VDR) and NF-κB mRNAs in vitamin D (VD) supplemented multiple sclerosis (MS) patients., Methods: RRMS patients received 50,000 IU vitamin D3/week as an intra-muscular injection for 2 months. Blood samples were obtained from 30 MS patients before and after VD supplementation and 32 healthy individuals, and then VDR and NF-κB mRNA levels were measured by real time PCR method and analyzed with independent and paired t-tests. Moreover, some correlations were performed between the expression levels of selected genes and some clinical features of MS and control groups., Results: Surprisingly, the expression level of VDR mRNA significantly decreased after 2 months supplementation with VD in our selected patients and in contrast, the level of serum 25(OH) D increased after supplementation. Although, we didn't find any significant difference in the expression level of NF-κB gene before and after treatment with VD, its expression significantly decreased in untreated MS cases compared with healthy controls., Conclusion: In conclusion, we found some new evidences from the molecular mechanism of vitamin D effectiveness in MS treatment. Also, we need more functional studies to find the effect of VD on the expression level of VDR mRNA., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Background: Several lines of evidence indicate that the active form of vitamin D has an anabolic effect on skeletal muscle. Eldecalcitol, an analogue of the active form of vitamin D, has the potential to increase bone density and decrease fracture risk. The objective of this study was to investigate the effect of eldecalcitol in C2C12 myogenic cells., Methods: C2C12 cells were grown to confluency and the culture medium was replaced with low-glucose DMEM containing 2% horse serum. Eldecalcitol was added at a concentration of 1, 10 or 100 nM. Gene expression profiles of vitamin D receptor (VDR), MyoD, IGF-1, neonatal myosin heavy chain (MHC), and the fast MHC subtypes Ia, IIa, IIb and IId/x were analyzed by quantitative RT-PCR. Protein expression of MHC subtypes was evaluated by western blotting and immunostaining., Results: Eldecalcitol upregulated gene expression of VDR, MyoD and IGF-1. Incubation with eldecalcitol in the absence of serum followed by the addition of serum after 1 h was associated with greater increases in the expression of these genes compared with co-incubation with eldecalcitol and serum. Gene expression of MHC subtypes IIa, IIb and IId/x was significantly increased by eldecalcitol. Protein expression of fast MHC subtypes was significantly increased by eldecalcitol at 1 and 10 nM., Conclusion: Similar to the active form of vitamin D, eldecalcitol had an anabolic effect on fast MHC subtypes. Taking into account its pharmacokinetic profile, eldecalcitol is expected to be beneficial for the maintenance and improvement of muscle function in elderly individuals., (Copyright © 2016 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Dermal wound healing, in which transforming growth factor beta 1 (TGFβ1) plays an important role, is a complex process. Previous studies suggest that vitamin D has a potential regulatory role in TGFβ1 induced activation in bone formation, and there is cross-talk between their signaling pathways, but research on their effects in other types of wound healing is limited. The authors therefore wanted to explore the role of vitamin D and its interaction with low concentration of TGFβ1 in dermal fibroblast-mediated wound healing through an in vitro study. Human dermal fibroblasts were treated with vitamin D, TGFβ1, both, or vehicle, and then the wound healing functions of dermal fibroblasts were measured. To further explore possible mechanisms explaining the synergistic effect of vitamin D and TGFβ1, targeted gene silencing of the vitamin D receptor was performed. Compared to either factor alone, treatment of fibroblasts with both vitamin D and low concentration of TGFβ1 increased gene expression of TGFβ1, connective tissue growth factor, and fibronectin 1, and enhanced fibroblast migration, myofibroblast formation, and collagen production. Vitamin D receptor gene silencing blocked this synergistic effect of vitamin D and TGFβ1 on both collagen production and myofibroblast differentiation. Thus a synergistic effect of vitamin D and low TGFβ1 concentration was found in dermal fibroblast-mediated wound healing in vitro. This study suggests that supplementation of vitamin D may be an important step to improve wound healing and regeneration in patients with a vitamin D deficiency., (Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.)

Purpose: The goal of this systematic review is to evaluate the efficacy and safety of paricalcitol versus active non-selective vitamin D receptor activators (VDRAs) for secondary hyperparathyroidism (SHPT) management in chronic kidney disease (CKD) patients., Methods: PubMed, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), clinicaltrials.gov (inception to September 2015), and ASN Web site were searched for relevant studies. A meta-analysis of randomized controlled trials (RCTs) and quasi-RCTs that assessed the effects and adverse events of paricalcitol and active non-selective VDRA in adult CKD patients with SHPT was performed using Review Manager 5.2., Results: A total of 10 trials involving 734 patients were identified for this review. The quality of included trials was limited, and very few trials reported all-cause mortality or cardiovascular calcification without any differences between two groups. Compared with active non-selective VDRAs, paricalcitol showed no significant difference in both PTH reduction (MD -7.78, 95% CI -28.59-13.03, P = 0.46) and the proportion of patients who achieved the target reduction of PTH (OR 1.27, 95% CI 0.87-1.85, P = 0.22). In addition, no statistical differences were found in terms of serum calcium, episodes of hypercalcemia, serum phosphorus, calcium × phosphorus products, and bone metabolism index., Conclusions: Current evidence is insufficient, showing paricalcitol is superior to active non-selective VDRAs in lowering PTH or reducing the burden of mineral loading. Further trials are required to prove the tissue-selective effect of paricalcitol and to overcome the limitation of current research.

Although emerging evidence suggests that vitamin D has beneficial effects in the cardiovascular health, the underlying mechanisms are far from fully elucidated. Given the indispensable role of neuregulin-1 (NRG1)/ErbB signaling in the cardiovascular system, the present study investigated the influences of prolonged administration of calcitriol, the active form of vitamin D, on the NRG1/ErbB system. We examined the protein expression of NRG1, ErbB receptors (ErbB2 and ErbB4) and their phosphorylated forms in the myocardium of rats following 6-week administration of calcitriol (50 ng/kg/day or 100 ng/kg/day). We further assessed the myocardial vitamin D receptor (VDR) to confirm the effect of calcitriol treatment. Additionally, serum neuregulin-1 level was also analyzed. Generally, calcitriol enhanced myocardial VDR expression and NRG1/ErbB signaling. Calcitriol increased NRG1 protein level at the higher dose, while both doses promoted ErbB2 and phosphorylated ErbB2 expression. Although calcitriol has no significant influence on ErbB4 expression, phosphorylated ErbB4 receptors were enhanced at the higher dose. Furthermore, the serum neuregulin-1 concentration was increased at both doses. Overall, our data firstly showed that chronic calcitriol administration enhanced NRG1/ErbB signaling in the heart, indicating a novel mechanism underlying the cardiac effects of vitamin D.

Background: Recently, it has been reported that urinary angiotensinogen levels is a specific index of the intrarenal renin-angiotensin-aldosterone system (RAAS) status and it is significantly correlated with urinary albumin:creatinine (Cr) ratio in hypertensive patients. The aim of the present study was to assess the effect of activation of the Vitamin D receptor with calcitriol on albuminuria and urinary angiotensinogen as a novel biomarker of the intra-renal RAAS status in patients with diabetic nephropathy (DN)., Methods: Ninety-eight patients with type 2 diabetes and albuminuria who were treated with RAAS inhibitors (angiotensin-converting enzyme inhibitor (ACE-i) or angiotensin receptor blocker (ARB)) have participated in this study. Patients were randomized to receive either placebo (n = 50) or 0.25 μg/day calcitriol (n = 48). We have examined urinary albumin:Cr ratio and urinary angiotensinogen:Cr ratio before and 24 weeks later after treatment in both group., Results: The mean urinary albumin:Cr ratio and urinary angiotensinogen:Cr ratio were significantly higher in patients with DN than in normal controls (p < 0.001). Urinary angiotensinogen:Cr ratio was significantly, positively correlated with urinary albumin:Cr ratio in both groups (in the placebo group; p = 0.01, r = 0.4236, in calcitriol group; p = 0.01, r = 0.4564)., Conclusion: These data indicated that administration of Vitamin D receptor activator in combination with RAAS inhibitors had an additional benefit in lowering albuminuria in patients with DN. More pronounced reduction of urinary albumin:Cr ratio that was positively correlated with angiotensinogen:Cr ratio in calcitriol group suggested that Vitamin D receptor activation might blunt albuminuria by reducing urinary angiotensinogen levels reflecting intra-renal RAAS status.

Unlabelled: Treatment with curcumin attenuated modeled microgravity-induced bone loss, possibly through abating oxidative stress and activating vitamin D receptor. Curcumin might be an effective countermeasure for microgravity-induced bone loss but remains to be tested in humans., Introduction: Bone loss is one of the most important complications for human crewmembers who are exposed to long-term microgravity in space and also for bedridden people. The aim of the current study was to elucidate whether treatment with curcumin attenuated bone loss induced by microgravity., Methods: We used hind-limb suspension (HLS) and rotary wall vessel bioreactor (RWVB) to model microgravity in vivo and in vitro, respectively. We investigated the effects of curcumin consumption (40 mg kg(-1) body weight day(-1), via daily oral gavages) on Sprague-Dawley (SD) rats exposed to HLS for 6 weeks. Then, we investigated the effects of incubation with curcumin (4 μM) on MC3T3-E1 and RAW264.7 cells cultured in RWVB., Results: Curcumin alleviated HLS-induced reduction of bone mineral density in tibiae and preserved bone structure in tibiae and mechanical strength in femurs. Curcumin alleviated HLS-induced oxidative stress marked by reduced malondialdehyde content and increased total sulfhydryl content in femurs. In cultured MC3T3-E1 cells, curcumin inhibited modeled microgravity-induced reactive oxygen species (ROS) formation and enhanced osteoblastic differentiation. In cultured RAW264.7 cells, curcumin reduced modeled microgravity-induced ROS formation and attenuated osteoclastogenesis. In addition, curcumin upregulated vitamin D receptor (VDR) expression in femurs of rats exposed to HLS and MC3T3-E1 cells exposed to modeled microgravity., Conclusion: Curcumin alleviated HLS-induced bone loss in rats, possibly via suppressing oxidative stress and upregulating VDR expression.

ANG II type 1 receptor blockade (AT1R-BLK) is used extensively to slow down the progression of proteinuric kidney diseases. We hypothesized that AT1R-BLK provides podocyte protection through regulation of silencing mediator of retinoic acid and thyroid hormone receptor (SMRT) and vitamin D receptor (VDR) expression under adverse milieus such as high glucose and human immunodeficiency virus infection. Both AT1R-BLK and VDR agonists (VDAs) stimulated VDR complex formation that differed not only in their composition but also in their functionality. AT1R-BLK-induced VDR complexes contained predominantly unliganded VDR, SMRT, and phosphorylated histone deacetylase 3, whereas VDA-VDR complexes were constituted by liganded VDR and CREB-binding protein/p300. AT1R-BLK-induced complexes attenuated podocyte acetyl-histone 3 levels as well as cytochrome P-450 family 24A1 expression, thus indicating their deacetylating and repressive properties. On the other hand, VDA-VDR complexes not only increased podocyte acetyl-histone 3 levels but also enhanced cytochrome P-450 family 24A1 expression, thus suggesting their acetylating and gene activation properties. AT1R-BLK- induced podocyte SMRT inhibited expression of the proapoptotic gene BAX through downregulation of Wip1 and phosphorylation of checkpoint kinase 2 in high-glucose milieu. Since SMRT-depleted podocytes lacked AT1R-BLK-mediated protection against DNA damage, it appears that SMRT is necessary for DNA repairs during AT1R-BLK. We conclude that AT1R-BLK provides podocyte protection in adverse milieus predominantly through SMRT expression and partly through unliganded VDR expression in 1,25(OH)2D-deficient states; on the other hand, AT1R-BLK contributes to liganded VDR expression in 1,25(OH)2D-sufficient states., (Copyright © 2015 the American Physiological Society.)

The use of vitamin D receptor activators (VDRAs) is an independent predictor of a lower risk of death from cardiovascular disease (CVD) in patients with chronic kidney disease (CKD). We examined whether the use of VDRAs and other CKD-mineral bone disorder (MBD)-related factors are associated with incident CVD or death after CVD in hemodialysis patients. This is a historical cohort study of 37 690 prevalent hemodialysis patients without previous history of CVD at the end of 2004 extracted from a nationwide registry in Japan. The key exposure was the use of VDRAs, and the outcomes were incident CVD (myocardial infarction, cerebral infarction, cerebral hemorrhage, and sudden death) and death after CVD during the 1-year follow-up. VDRAs were used in 57% of the subjects at baseline. We identified 2433 patients with incident CVD and 397 deaths after the events. In multivariate logistic regression models, independent predictors of incident CVD were non-use of VDRA, higher intact PTH, non-use of calcium-based phosphate-binder, and non-use of non-calcium-based phosphate binder. Risk of death after CVD was not significantly associated with VDRA, whereas it was lower in those with lower corrected calcium, and the risk was higher in those with higher phosphate and in non-users of calcium-based phosphate binders. The use of VDRAs was associated with a lower risk of incident CVD but not with death after CVD in this large cohort of hemodialysis patients. The CKD-MBD-related predictors of poor outcomes are associated with the risk of incident CVD, the risk of death after CVD, or both., (© 2014 The Authors. Therapeutic Apheresis and Dialysis © 2014 International Society for Apheresis.)

Vitamin D is a secosteroid, in which the B ring of the steroid structure is ruptured. The active form of vitamin D, 1α, 25-dihydroxyvitamin D3 [1,25 (OH) 2D3], regulates numerous physiological and pharmacological processes, including bone and calcium homeostasis, cellular growth and differentiation, immunity, and cardiovascular function, through binding to the vitamin D receptor (VDR), a member of the nuclear receptor superfamily. VDR ligands are promising in the treatment of bone and mineral disorders, cancer, autoimmune disease, and cardiovascular disease. However, the calcemic effect of vitamin D derivatives has limited their clinical application. Recently, nonsecosteroidal VDR modulators (VDRMs) have been developed. Several VDRMs have better therapeutic efficacy when compared to 1,25 (OH) 2D3 in experimental models of cancer and osteoporosis with less induction of hypercalcemia. Analysis of crystal structures reveals that nonsecosteroidal VDRMs bind to VDR in a position similar to 1,25 (OH) 2D3 and that hydrogen bond interactions between ligands and VDR are important for VDR transactivation. Pharmacokinetics of nonsecosteroidal VDRMs may be related to their less calcemic effect. Nonsecosteroidal VDRMs can induce VDR conformation distinct from that by 1,25 (OH) 2D3, likely leading to selective gene expression. Although the potential risk of unexpected adverse effects needs be considered, further development of nonsecosteroidal VDRMs should expand the possibility of VDR-targeted approaches.

Epidemiological studies have revealed that vitamin D deficiency increases the risk of cancer development and is associated with its poor prognosis. In the classical view of calcium metabolism, vitamin D is activated by CYP27B1 in the kidney and promotes calcium absorption in the intestine as a hormone. Besides such a classical role, vitamin D is known to exert multiple extra-skeletal actions through CYP27B1 and vitamin D receptor (VDR) that is expressed in a wide variety of extra-renal tissues and cell types. As one of its "non-classical" actions, vitamin D has been shown to have anti-cancer activity by various mechanisms including inhibition of cellular proliferation, induction of apoptosis, stimulation of differentiation, suppression of tumor invasion, metastasis, and angiogenesis. Despite numerous promising results at the cellular and animal levels, clinical trials have so far failed to provide definitive evidence for anti-cancer effect of vitamin D.

To express its biological action, active vitamin D3 (1α,25-dihydroxyvitamin D3) interacts with three proteins : vitamin D binding protein (DBP), vitamin D receptor (VDR), and CYP24A1. This article explains how eldecalcitol interacts with these three proteins to achieve its mode of action. The main feature of eldecalcitol's molecular structure is the 3-hydroxypropyloxy group (3-HP group) at the 2β-position. When interacting with DBP, eldecalcitol tightly binds to DBP via the 3-HP group and enhances systemic stability of eldecalcitol. By binding to VDR, the 3-HP group stabilizes the eldecalcitol-VDR complex, which leads to high efficacy. The 3-HP group also interferes with the binding to CYP24A1, which induces residence to CYP24A1 and liver metabolism. These protein interactions constitute the mode of action of eldecalcitol.

Introduction: The vitamin D receptor (VDR) is a promising drug target in the treatment of cancer, autoimmune disease, inflammation, infection and cardiovascular disease, as well as bone and mineral disorders. Although many VDR ligands have been developed and shown to activate VDR in vitro and in vivo, including vitamin D derivatives and non-secosteroidal compounds, a principal adverse effect of hypercalcemia has limited their clinical application., Areas Covered: We summarize recent patent activity regarding VDR ligands, including vitamin D derivatives, non-secosteroidal compounds and tissue-selective prodrugs, alongside their therapeutic applications. The potential for use of VDR ligands in the treatment of hepatic fibrosis, pancreatic fibrosis and neuronal disease is also reviewed., Expert Opinion: Several VDR ligands have been shown to have increased therapeutic efficiency in experimental models of cancer, inflammation and cardiovascular disease, and to exhibit function-selective and/or tissue-selective activity. The underlying molecular and pharmacological mechanisms remain to be elucidated. Further studies, both basic and applied, should make successful VDR-targeting therapy possible.

Vitamin D, beyond its classical roles in the regulation of calcium and phosphorus homeostasis and bone metabolism, has been implicated in multiple pathological processes, including progression from inflammation to cancer development and also involvement in autoimmune diseases as well as cardiovascular disorders. In this review, we shall discuss the different roles of vitamin D and its therapeutic targets in different gastrointestinal diseases, focusing on colorectal cancer (CRC) and inflammatory bowel disease (IBD). To this end, vitamin D deficiency has been identified as a risk factor of CRC. On the other hand the active metabolite of vitamin D, 1, 25- dihydroxyvitamin D3 (1, 25(OH)2D3) has multiple anti-cancerous benefits including inhibition of proliferation, induction of apoptosis, promotion of differentiation and suppression of angiogenesis in tumors. In IBD, vitamin D is involved in the pathogenic process through the normalization of immune responses in the colon. With these experimental findings, well-designed and large-scale clinical trials are warranted to further define the therapeutic action of vitamin D in the prevention and/or treatment of IBD and further on CRC in humans.

Background: Coronary heart disease (CHD) is the number one cause of death in the US. The adipokine adiponectin has been studied intensively for presenting and inversed association with almost every stage of CHD. For instance, the evaluation of molecules capable of enhancing endogenous adiponectin expression is well justified. In this study, we investigated the effect of the vitamin D receptor activator (VDRA) paricalcitol and the angiotensin-converting enzyme inhibitor (ACEI) enalapril on adiponectin expression, lipid profiles, adenosine monophosphate activated protein kinase (AMPK) expression, monocyte chemo-attractant protein-1 (MCP-1), tumor necrosis factor-alpha (TNFα),cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), antioxidant capacity, CuZn-superoxide dismutase (CuZn-SOD), Mn-SOD, NADPH p22phox subunits, inducible nitric oxidesynthase (iNOS), endothelial marker eNOS, and 81 atherosclerosis-related genes in ApoE-deficient mice., Method: Seven-week-old ApoE-deficient mice were treated for 16 weeks as follows: Group 1, ApoE vehicle control (intraperitoneal [i.p.] 100 µl propylene glycol); Group 2, ApoE-paricalcitol (200 ng i.p., 3/week); Group 3, ApoE-Enalapril (30 mg/kg daily); Group 4, ApoE-paricalcitol + enalapril (described dosing); and Group 5, wild-type control (C57BLV)., Results: All treated groups presented significant changes in circulating and cardiac adiponectin, cardiac cholesterol levels, AMPK, MCP-1, TNF-α, COX-2, iNOS, eNOS, CuZn-SOD, Mn-SOD and p22phox. There were 15 genes that differed in their expression, 5 of which are involved in cardioprotection and antithrombotic mechanisms: Bcl2a1a, Col3a1, Spp1 (upregulated), Itga2, and Vwf (downregulated)., Conclusion: Together, our data presented a novel role for VDRA and ACEI in reducing factors associated with CHD that may lead to the discovery of new therapeutic venues., (© The Author(s), 2014.)

Purpose of Review: Current data clearly support an interaction of vitamin D with cells of the immune system apart from its regulatory role in calcium homeostasis. The discovery that immune cells express the vitamin D receptor and are capable of metabolizing circulating 25-hydroxyvitamin D into its active form, 1,25-dihydroxyvitamin D, has revolutionized the field and suggested a regulatory role on both the innate and adaptive immune systems., Recent Findings: Of particular interest with respect to infectious diseases, 1,25-dihydroxyvitamin D has been shown to trigger the production of antimicrobial peptides with a direct pathogen-killing capacity. Interestingly, pathogen-derived components influence the key players in the vitamin D metabolizing pathway, further supporting such an interaction., Summary: Here, we review the potential mechanisms of vitamin D in promoting the innate immune response against infectious agents and discuss the possible implications for such a response in the prevention of or the intervention in various infectious diseases.

Introduction: The hypothesis that retiferols are a novel class of vitamin D analogs with therapeutic potential has been recently proved. The CD-ring of vitamin D, originated from a steroid precursor, is not necessary for biological activity. The retiferol, disubstituted at C-13, was bound to the ligand-binding domain (LBD) of vitamin D receptor (VDR) just like the vitamin D hormone [1,25-(OH)2D3]. This finding opens the way for retiferols as a novel class of vitamin D therapeutics., Areas Covered: This review presents the concept of retiferols and their structure evolution. Medicinal chemistry and therapeutic perspective of retiferols are reviewed showing how these vitamin D analogs became a source of potential therapeutics., Expert Opinion: Docking experiments and molecular modeling have shown that positioning of vitamin D analog at the LBD of VDR is not disturbed by deletion of a large portion of the vitamin D, exactly as hypothesized. Twenty years of structural modifications have shown that removal of the CD-ring fragment and regioselective methylation results in an almost complete loss of the undesired calcemic activity of retiferol while gaining the agonistic activity comparable to that of 1,25-(OH)2D3.

Aim: To discover novel [20(OH)D3] analogs as antiproliferative therapeutics., Materials and Methods: We studied in vitro liver microsome stability, in vivo toxicity using mice, vitamin D receptor (VDR) translocation, in vitro antiproliferative effect, CYP enzyme metabolism., Results: 20S- and 20R(OH)D3 had reasonable half-lives of 50 min and 30 min (average) respectively in liver microsomes. They were non-hypercalcemic at a high dose of 60 μg/kg. Three new 20(OH)D3 analogs were designed, synthesized and tested. They showed higher or comparable potency for inhibition of proliferation of normal keratinocytes and in the induction of VDR translocation from cytoplasm to nucleus, compared to 1,25(OH)2D3. These new analogs demonstrated different degrees of metabolism through a range of vitamin D-metabolizing CYP enzymes., Conclusion: Their lack of calcemic toxicity at high doses and their high biological activity suggest that this novel 20(OH)D3 scaffold may represent a promising platform for further development of therapeutically-useful agents.

7-Dehydrocholesterol (7-DHC) is a common precursor of vitamin D3 and cholesterol. Although various oxysterols, oxygenated cholesterol derivatives, have been implicated in cellular signaling pathways, 7-DHC metabolism and potential functions of its metabolites remain poorly understood. We examined 7-DHC metabolism by various P450 enzymes and detected three metabolites produced by sterol 27-hydroxylase (CYP27A1) using high-performance liquid chromatography. Two were further identified as 25-hydroxy-7-DHC and 26/27-hydroxy-7-DHC. These 7-DHC metabolites were detected in serum of a patient with Smith-Lemli-Opitz syndrome. Luciferase reporter assays showed that 25-hydroxy-7-DHC activates liver X receptor (LXR) α, LXRβ and vitamin D receptor and that 26/27-hydroxy-7-DHC induces activation of LXRα and LXRβ, although the activities of both compounds on LXRs were weak. In a mammalian two-hybrid assay, 25-hydroxy-7-DHC and 26/27-hydroxy-7-DHC induced interaction between LXRα and a coactivator fragment less efficiently than a natural LXR agonist, 22(R)-hydroxycholesterol. These 7-DHC metabolites did not oppose agonist-induced LXR activation and interacted directly to LXRα in a manner distinct from a potent agonist. These findings indicate that the 7-DHC metabolites are partial LXR activators. Interestingly, 25-hydroxy-7-DHC and 26/27-hydroxy-7-DHC suppressed mRNA expression of sterol regulatory element-binding protein 1c, an LXR target gene, in HepG2 cells and HaCaT cells, while they weakly increased mRNA levels of ATP-binding cassette transporter A1, another LXR target, in HaCaT cells. Thus, 7-DHC is catabolized by CYP27A1 to metabolites that act as selective LXR modulators., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

22-oxacalcitriol (OCT) is a vitamin D3 analog and a vitamin D receptor activator (VDRA) that is used as a drug for secondary hyperparathyroidism (SHPT) and has been available clinically in Japan since 2000. The pharmacological characteristics of OCT include rapid clearance from the systemic circulation compared to that of calcitriol, good tissue distribution, and relatively long retention in the nucleus in parathyroid cells. In clinical studies, OCT has been shown to decrease the parathyroid hormone (PTH) level with an effect equivalent to that of calcitriol. Other reports show that OCT produces superior improvement of bone metabolism compared to calcitriol. Treatment with ultrasound-guided direct injection of OCT into the parathyroid has also been attempted. In animal studies, OCT does not influence the blood Ca or P level and is less likely to promote progression of calcification in cardiovascular tissue. The influence of VDRAs including OCT on the progression of cardiovascular lesions and survival in SHPT patients requires further studies.

Introduction: Despite the developments in modern medicine, acute renal injury is still a challenging and common health problem. It is well known that ischaemia and reperfusion takes place in pathological mechanisms. Efforts to clarify the pathophysiology and interventions to improve outcomes are essential. Our study aimed to investigate whether the prophylactic use of paricalcitol is beneficial in renal ischaemia/reperfusion (I/R) injury., Methods: Twenty-four Wistar albino rats were assigned randomly to four groups. Right nephrectomies were performed at the time of renal arterial clamping. Sham surgery was performed on the rats in group 1. For the rats in group 2, the left renal artery was clamped for 45 minutes. The rats in group 3 received paricalcitol for seven days (0.2μg/kg/day); following this, a right nephrectomy and left renal arterial clamping were not performed. The rats in group 4 received paricalcitol for seven days (0.2μg/kg/day); following this, a right nephrectomy and left renal arterial clamping for 45 minutes were performed. Tissue thiobarbituric acid reactive substances (TBARS), superoxide dismutase, sulfhydryl groups as well as nitric oxide metabolites, serum urea and creatinine levels were measured for all four groups., Results: In group 4, there were some improvements in terms of TBARS, nitrite, nitrate, superoxide dismutase and creatinine levels. In the histopathological evaluation, paricalcitol therapy improved tubular necrosis and medullar congestion but there was no significant difference in terms of tubular cell swelling, cellular vacuolisation or general damage. Immunohistopathological examination revealed lower scores for vascular endothelial growth factor in the group 4 rats than in group 2., Conclusions: Paricalcitol therapy improved renal I/R injury in terms of serum and histopathological parameters. These potential beneficial effects need to be further investigated.

Backgrounds/aims: It has been previously demonstrated that vitamin D acts as a prognostic indicator of gastric cancer and may be correlated with the incidence risk of gastric cancer. However, the effect of 1,25-dihydroxyvitamin D3 on the apoptosis of human gastric cancer cells is unclear. The aim of this study was to determine whether 1,25-dihydroxyvitamin D3 induced the cellular apoptosis of BGC-823 gastric cancer cells and to determine the potential mechanism of action., Methodology: We demonstrate that 1,25-dihydroxyvitamin D3 induced the apoptosis of gastric cancer cells via the processing of PARP and cleavage of caspase 3. Additionally, an increase in BAX expression and a decrease in ERK1/2 and AKT phosphorylation were associated with 1,25-dihydroxyvitamin D3-induced apoptosis. The mRNA expression levels of VDR, CYP24A1, and p21 were increased significantly following 1,25-dihydroxyvitamin D3 treatment., Conclusions: These findings suggest that 1,25-dihydroxyvitamin D3 exerts tumor-suppressive effects on BGC-823 human gastric cancer cells.

Changing the geminal methyl groups on 1α,25-dihydroxyvitamin D3 and its analogues to the deuterio versions generally improves the bioactivity. Derivatives of 1α,25-dihydroxyvitamin D3 with two chains emanating at C20, commonly referred to as gemini, are subject to the same phenomenon. Additionally, gemini with different side chains are susceptible to bioactivity differentials where the C17-C20 threo configuration usually imparts higher activity than the corresponding erythro arrangement. In an effort to analyze the deuterium effect on gemini with minimal diastereotopic distortion, we synthesized gemini with equal side chains but introduced deuterium diastereospecifically on either chain. We solved the crystal structures of these compounds in the zebra fish zVDR ligand binding domain as complexes with NCoA-2 coactivator peptide and correlated the findings with growth inhibition in a breast cancer cell line.