Immuno-Stimulating Activity of 1,25-Dihydroxyvitamin D in Blood Cells from Five Healthy People and in Blasts from Five Patients with Leukemias and Pre-Leukemic States.

(1) Hematological malignancies are characterized by an immortalization, uncontrolled proliferation of blood cells and their differentiation block, followed by the loss of function. The primary goal in the treatment of leukemias is the elimination of rapidly proliferating leukemic cells (named blasts). However, chemotherapy, which removes proliferating blasts, also prevents the remaining immune cells from being activated. Acute leukemias affect elderly people, who are often not fit to survive aggressive chemotherapy. Therefore, there is a need of milder treatment, named differentiation therapy, which might simulate the immune system of the patient. 1,25-Dihydroxyvitamin D, or low-calcemic analogs of this compound, were proposed as supporting therapy in acute leukemias. (2) Bone marrow blasts from patients with hematological malignancies, and leukocytes from healthy volunteers were ex vivo exposed to 1,25-dihydroxyvitamin D, and then their genomes and transcriptomes were investigated. (3) Our analysis indicates that 1,25-dihydroxyvitamin D regulates in blood cells predominantly genes involved in immune response, such as CAMP (cathelicidin antimicrobial peptide), CP (ceruloplasmin), CXCL9 (C-X-C motif chemokine ligand 9), CD14 (CD14 molecule) or VMO1 (vitelline membrane outer layer 1 homolog). This concerns blood cells from healthy people, as well as blasts from patients with hematological malignancies. In addition, in one patient, 1,25-dihydroxyvitamin D significantly downregulated transcription of genes responsible for cell division and immortalization. (4) In conclusion, the data presented in this paper suggest that addition of 1,25-dihydroxyvitamin D to the currently available treatments would stimulate immune system, inhibit proliferation and reduce immortal potential of blasts.

Nonaqueous Capillary Electrophoretic Separation of Analogs of (24R)-1,24-Dihydroxyvitamin D3 Derivative as Predicted by Quantum Chemical Calculations.

Nonaqueous capillary electrophoretic (NACE) separation was obtained of analogs of (24R)-1,24-dihydroxyvitamin D3 derivative (calcipotriol) as predicted by quantum chemical calculations supported by the density functional theory (DFT). Among the key electronic properties investigated, absolute values of the dipole polarizability and energy gap between HOMO and LUMO molecular orbitals of the analog molecules differ significantly for particular analogs, and there is a direct relationship with their electrophoretic migration time. These differences and relationships suggest that the structurally related analogs should be separable in the electrostatic field. Indeed, the robust, sensitive, and rapid NACE method was first developed for the identification and determination of the anticancer analog of calcipotriol (coded PRI-2205) and its process-related impurities (coded PRI-2201, PRI-2203, and PRI-2204) in organic and aqueous biological solutions. The direct relation between the calculated electronic properties of the analogs and the experimental electrophoretic migration time could be a promising prospect for theoretically predicting the electrophoretic separations.

Vitamin D Compounds PRI-2191 and PRI-2205 Enhance Anastrozole Activity in Human Breast Cancer Models.

1,25-Dihydroxycholecalciferol, the hormonally active vitamin D3 metabolite, is known to exhibit therapeutic effects against breast cancer, mainly by lowering the expression of estrogen receptors and aromatase activity. Previously, the safety of the vitamin D active metabolite (24R)-1,24-dihydroxycholecalciferol (PRI-2191) and 1,25(OH)2D3 analog PRI-2205 was tested, and the in vitro activity of these analogs against different cancer cell lines was studied. We determined the effect of the two vitamin D compounds on anastrozole (An) activity against breast cancer based on antiproliferative activity, ELISA, flow cytometry, enzyme inhibition potency, PCR, and xenograft study. Both the vitamin D active metabolite and synthetic analog regulated the growth of not only estrogen receptor-positive cells (T47D and MCF-7, in vitro and in vivo), but also hormone-independent cancer cells such as SKBR-3 (HER-2-positive) and MDA-MB-231 (triple-negative), despite their relatively low VDR expression. Combined with An, PRI-2191 and PRI-2205 significantly inhibited the tumor growth of MCF-7 cells. Potentiation of the antitumor activity in combined treatment of MCF-7 tumor-bearing mice is related to the reduced activity of aromatase by both An (enzyme inhibition) and vitamin D compounds (switched off/decreased aromatase gene expression, decreased expression of other genes related to estrogen signaling) and by regulation of the expression of the estrogen receptor ERα and VDR.

Differential Response of Lung Cancer Cells, with Various Driver Mutations, to Plant Polyphenol Resveratrol and Vitamin D Active Metabolite PRI-2191.

Plant polyphenols and vitamins D exhibit chemopreventive and therapeutic anticancer effects. We first evaluated the biological effects of the plant polyphenol resveratrol (RESV) and vitamin D active metabolite PRI-2191 on lung cancer cells having different genetic backgrounds. RESV and PRI-2191 showed divergent responses depending on the genetic profile of cells. Antiproliferative activity of PRI-2191 was noticeable in EGFRmut cells, while RESV showed the highest antiproliferative and caspase-3-inducing activity in KRASmut cells. RESV upregulated p53 expression in wtp53 cells, while downregulated it in mutp53 cells with simultaneous upregulation of p21 expression in both cases. The effect of PRI-2191 on the induction of CYP24A1 expression was enhanced by RESV in two KRASmut cell lines. The effect of RESV combined with PRI-2191 on cytokine production was pronounced and modulated. RESV cooperated with PRI-2191 in regulating the expression of IL-8 in EGFRmut cells, while OPN in KRASmut cells and PD-L1 in both cell subtypes. We hypothesize that the differences in response to RESV and PRI-2191 between EGFRmut and KRASmut cell lines result from the differences in epigenetic modifications since both cell subtypes are associated with the divergent smoking history that can induce epigenetic alterations.

Hailey-Hailey disease successfully treated with vitamin D oral supplementation.

Hailey-Hailey disease (HHD) also known as familial benign chronic pemphigus is a rare autosomal dominant genodermatosis. HHD treatment is often not satisfactory and hence, various modalities of treatment have been tried. We describe the case of a 37-year-old woman with a 2 years history of macerated erythematous plaques along with erosions, fissures, and crusts located on axillae and submammary areas, successfully treated with only oral supplementation of vitamin D (800 I.U./die) for 3 months. We reported this case to suggest that oral vitamin D may be enumerated in the various treatments proposed for HHD so far due to its rapid efficacy on skin lesions and symptoms.

Evolving Role of Vitamin D in Immune-Mediated Disease and Its Implications in Autoimmune Hepatitis.

Vitamin D has immunomodulatory, anti-inflammatory, antioxidant, and anti-fibrotic actions that may impact on the occurrence and outcome of immune-mediated disease. The goals of this review are to describe the nature of these expanded roles, examine the implications of vitamin D deficiency in autoimmune hepatitis, and identify opportunities for future investigation. Abstracts were identified in PubMed by multiple search terms. Full-length articles were selected for review, and secondary and tertiary bibliographies were developed. Vitamin D receptors are expressed on the principal cell populations involved in the innate and adaptive immune responses. Macrophages and dendritic cells can produce 1,25-dihydroxyvitamin D within the microenvironment. This active form of vitamin D can inhibit immune cell proliferation, promote an anti-inflammatory cytokine profile, expand regulatory T cells, enhance glucocorticoid actions, increase glutathione production, and inhibit hepatic stellate cells. Vitamin D deficiency has been commonly present in patients with immune-mediated liver and non-liver diseases, and it has been associated with histological severity, advanced hepatic fibrosis, and non-response to conventional glucocorticoid therapy in autoimmune hepatitis. Vitamin D analogues with high potency, low calcemic effects, and independence from hepatic hydroxylation are possible interventions. In conclusion, vitamin D has properties that could ameliorate immune-mediated disease, and vitamin D deficiency has been a common finding in immune-mediated liver and non-liver diseases, including autoimmune hepatitis. Loss of vitamin D-dependent homeostatic mechanisms may promote disease progression. Vitamin D analogues that are independent of hepatic hydroxylation constitute an investigational opportunity to supplement current management of autoimmune hepatitis.

Differential and Overlapping Effects of 20,23(OH)2D3 and 1,25(OH)2D3 on Gene Expression in Human Epidermal Keratinocytes: Identification of AhR as an Alternative Receptor for 20,23(OH)2D3.

A novel pathway of vitamin D activation by CYP11A has previously been elucidated. To define the mechanism of action of its major dihydroxy-products, we tested the divergence and overlap between the gene expression profiles of human epidermal keratinocytes treated with either CYP11A1-derived 20,23(OH)2D3 or classical 1,25(OH)2D3. Both secosteroids have significant chemical similarity with the only differences being the positions of the hydroxyl groups. mRNA was isolated and examined by microarray analysis using Illumina's HumanWG-6 chip/arrays and subsequent bioinformatics analyses. Marked differences in the up- and downregulated genes were observed between 1,25(OH)2D3- and 20,23(OH)2D3-treated cells. Hierarchical clustering identified both distinct, opposite and common (overlapping) gene expression patterns. CYP24A1 was a common gene strongly activated by both compounds, a finding confirmed by qPCR. Ingenuity pathway analysis identified VDR/RXR signaling as the top canonical pathway induced by 1,25(OH)2D3. In contrast, the top canonical pathway induced by 20,23(OH)2D3 was AhR, with VDR/RXR being the second nuclear receptor signaling pathway identified. QPCR analyses validated the former finding by revealing that 20,23(OH)2D3 stimulated CYP1A1 and CYP1B1 gene expression, effects located downstream of AhR. Similar stimulation was observed with 20(OH)D3, the precursor to 20,23(OH)2D3, as well as with its downstream metabolite, 17,20,23(OH)3D3. Using a Human AhR Reporter Assay System we showed marked activation of AhR activity by 20,23(OH)2D3, with weaker stimulation by 20(OH)D3. Finally, molecular modeling using an AhR LBD model predicted vitamin D3 hydroxyderivatives to be good ligands for this receptor. Thus, our microarray, qPCR, functional studies and molecular modeling indicate that AhR is the major receptor target for 20,23(OH)2D3, opening an exciting area of investigation on the interaction of different vitamin D3-hydroxyderivatives with AhR and the subsequent downstream activation of signal transduction pathways in a cell-type-dependent manner.

Calcitriol and Its Analogs Establish the Immunosuppressive Microenvironment That Drives Metastasis in 4T1 Mouse Mammary Gland Cancer.

In our previous study, calcitriol and its analogs PRI-2191 and PRI-2205 stimulated 4T1 mouse mammary gland cancer metastasis. Therefore, we aimed to analyze the inflammatory response in 4T1-bearing mice treated with these compounds. Gene expression analysis of the splenocytes and regional lymph nodes demonstrated prevalence of the T helper lymphocytes (Th2) response with an increased activity of regulatory T (Treg) lymphocytes in mice treated with these compounds. We also observed an increased number of mature granulocytes and B lymphocytes and a decreased number of TCD4⁺, TCD4⁺CD25⁺, and TCD8⁺, as well as natural killer (NK) CD335⁺, cells in the blood of mice treated with calcitriol and its analogs. Among the splenocytes, we observed a significant decrease in NK CD335⁺ cells and an increase in TCD8⁺ cells. Calcitriol and its analogs decreased the levels of interleukin (IL)-1ß and IL-10 and increased the level of interferon gamma (IFN-γ) in the plasma. In the tumor tissue, they caused an increase in the level of IL-10. Gene expression analysis of lung tissue demonstrated an increased level of osteopontin (Spp1) and transforming growth factor ß (TGF-ß) mRNA. The expression of Spp1 was also elevated in lymph nodes. Calcitriol and its analogs caused prevalence of tumor-conducive changes in the immune system of 4T1 tumor-bearing mice, despite the induction of some tumor-disadvantageous effects.

Comparative evaluation of efficacy and safety of calcipotriol versus tacalcitol ointment, both in combination with NBUVB phototherapy in the treatment of stable plaque psoriasis.

BACKGROUND: Vitamin D analogues and NBUVB phototherapy are both well-established modalities of treatment in psoriasis. The objective of this open label, intraindividual, left right study was to compare two different vitamin D analogues, calcipotriol and tacalcitol, in combination with NBUVB phototherapy in chronic stable plaque psoriasis. METHODS: Thirty patients with stable plaque psoriasis were enrolled for a 12-week clinical trial. The target lesion on left side was treated topically with tacalcitol ointment once daily, while that on the right side was treated with calcipotriol ointment twice daily. NBUVB phototherapy was given thrice weekly. Efficacy was assessed by target plaque scoring. RESULTS: Both therapies resulted in statistically significant reduction in erythema, scaling, thickness and target plaque score, seen as early as 2 weeks into therapy. However, calcipotriol combination led to an earlier clearance of plaques and a lesser relapse rate than tacalcitol combination. The number of treatment sessions and cumulative NBUVB doses were significantly lower in the calcipotriol-treated group. CONCLUSION: Both vitamin D analogues appear to be safe, effective and cosmetically acceptable, calcipotriol being more efficacious, well tolerated with a rapid onset of action and a better maintenance of response.

Effect of narrow band ultraviolet B phototherapy as monotherapy or combination therapy for vitiligo: a meta-analysis.

BACKGROUND: The treatment of vitiligo is still one of the most difficult dermatological challenges, although there are many therapeutic options. Narrow band ultraviolet B (NB-UVB) phototherapy is considered to be a very important modality for generalized vitiligo. OBJECTIVE: The aim of this study was to explore whether a combination of NB-UVB and topical agents would be superior to NB-UVB alone for treating vitiligo. METHODS: We searched the electronic databases such as PUBMED, EMBASE, Cochrane Library, and Web of Science. The primary outcome was the proportion of ≥50% repigmentation (a clinical significance), and secondary outcome was the proportion of ≥75% repigmentation (an excellent response). RESULTS: Seven randomized controlled trials (RCTs) involving 240 patients (413 lesions) were included in this meta-analysis. The study showed no significant difference between NB-UVB combination therapy (NB-UVB and topical calcineurin inhibitor or vitamin D analogs) and NB-UVB monotherapy in the outcomes of ≥50% repigmentation and ≥75% repigmentation. However, lesions located on the face and neck had better results in ≥50% repigmentation (RR = 1.40, 95% CI 1.08-1.81) and ≥75% repigmentation (RR = 1.88, 95% CI 1.10-3.20) with NB-UVB and topical calcineurin inhibitor combination therapy vs. NB-UVB monotherapy. CONCLUSIONS: The meta-analysis suggested that adding neither topical calcineurin inhibitors nor topical vitamin-D3 analogs on NB-UVB can yield significantly superior outcomes than NB-UVB monotherapy for treatment of vitiligo. However, addition of topical calcineurin inhibitors to NB-UVB may increase treatment outcomes in vitiligo affecting face and neck.

Differential interference of vitamin D analogs PRI-1906, PRI-2191, and PRI-2205 with the renewal of human colon cancer cells refractory to treatment with 5-fluorouracil.

This study was aimed to determine whether hypocalcemic analogs of active forms of vitamins D modulate expression of genes related to stem-like phenotype in colon cancer cell lines HT-29 and HCT-116 undergoing renewal after the treatment with 5-fluorouracil (5-FU). Both lines express vitamin D receptor, but differ in differentiation stage and vitamin D sensitivity. Cells that resisted the 5-FU exposure were treated with synthetic analog of 1,25-dihydroxyvitamin D2 (PRI-1906) and analogs of 1,25-dihydroxyvitamin D3 (PRI-2191 and PRI-2205). Proliferative activity was more profoundly affected by vitamin D analogs in HT-29/5-FU than in HCT-116/5-FU cells. In HT-29/5-FU cells, analogs PRI-1906 and PRI-2191 downregulated the expression of genes related to survival, re-growth, and invasiveness during renewal, while PRI-2205 increased expression of genes related to differentiation only. In HCT-116/5-FU cells, PRI-2191 decreased the expression of stemness- and angiogenesis-related genes, whereas PRI-1906 augmented their expression. The effects in HCT-116/5-FU cells were observed at higher concentrations of the analogs than those used for HT-29/5-FU cells. Out of the series of analogs studied, PRI-2191 might be used to counteract the renewal of both moderately and poorly differentiated cancer cells following conventional treatment.

Tacalcitol: a useful adjunct to narrow-band ultraviolet-B phototherapy in vitiligo.

BACKGROUND: Phototherapy especially narrow-band UV-B (NBUVB) has been considered as mainstay of therapy in nonsegmental vitiligo (generalized type). Topical tacalcitol has also been claimed to be effective, either as monotherapy or as combination therapy. PURPOSE: Comparison of clinical efficacy and safety of NBUVB in combination with topical tacalcitol vs. NBUVB alone in vitiligo. MATERIAL & METHODS: Thirty patients with symmetrical vitiliginous lesions were enrolled for 24 weeks. Patients were instructed to apply tacalcitol ointment on right side of body once daily. In addition, the whole body was irradiated with NBUVB thrice weekly. All the patients were examined, and lesional photography was done. Patients were also followed up for 6 months post-treatment. RESULTS: Our study resulted in two key findings: (1) There was a statistically significant difference in mean percentage of repigmentation at 8, 16 and 24 weeks between combination therapy and NBUVB. (2) The mean cumulative dose and number of treatment sessions for initial repigmentation were significantly lower with combination therapy. No serious adverse effects were observed during the study period. CONCLUSION: Topical tacalcitol potentiates efficacy of NBUVB as it enhances extent of pigmentation, decrease time to repigmentation and lowers the cumulative doses of NBUVB, thereby leading to greater patient satisfaction and improved compliance.

Using yeast to model calcium-related diseases: example of the Hailey-Hailey disease.

Cross-complementation studies offer the possibility to overcome limitations imposed by the inherent complexity of multicellular organisms in the study of human diseases, by taking advantage of simpler model organisms like the budding yeast Saccharomyces cerevisiae. This review deals with, (1) the use of S. cerevisiae as a model organism to study human diseases, (2) yeast-based screening systems for the detection of disease modifiers, (3) Hailey-Hailey as an example of a calcium-related disease, and (4) the presentation of a yeast-based model to search for chemical modifiers of Hailey-Hailey disease. The preliminary experimental data presented and discussed here show that it is possible to use yeast as a model system for Hailey-Hailey disease and suggest that in all likelihood, yeast has the potential to reveal candidate drugs for the treatment of this disorder. This article is part of a Special Issue entitled: Calcium signaling in health and disease. Guest Editors: Geert Bultynck, Jacques Haiech, Claus W. Heizmann, Joachim Krebs, and Marc Moreau.

RORα and ROR γ are expressed in human skin and serve as receptors for endogenously produced noncalcemic 20-hydroxy- and 20,23-dihydroxyvitamin D.

RORα and RORγ are expressed in human skin cells that produce the noncalcemic 20-hydroxyvitamin D3 [20(OH)D3] and 20,23-dihydroxyvitamin D3 [20,23(OH)2D3]. Chinese hamster ovary (CHO) cells stably expressing a Tet-on RORα or RORγ expression vector and a ROR-responsive element (RORE)-LUC reporter, and a mammalian 2-hybrid model examining the interaction between the ligand binding domain (LBD) of RORα or RORγ with an LBD-interacting LXXLL-peptide, were used to study ROR-antagonist activities. These assays revealed that 20(OH)D3 and 20,23(OH)2D3 function as antagonists of RORα and RORγ. Moreover, 20(OH)D3 inhibited the activation of the promoter of the Bmal1 and G6pase genes, targets of RORα, and 20(OH)D3 and 20,23(OH)2D3 inhibited Il17 promoter activity in Jurkat cells overexpressing RORα or RORγ. Molecular modeling using crystal structures of the LBDs of RORα and RORγ revealed docking scores for 20(OH)D3, 20,23(OH)2D3 and 1,25(OH)2D3 similar to those of the natural ligands, predicting good binding to the receptor. Notably, 20(OH)D3, 20,23(OH)2D3, and 1,25(OH)2D3 inhibited RORE-mediated activation of a reporter in keratinocytes and melanoma cells and inhibited IL-17 production by immune cells. Our study identifies a novel signaling pathway, in which 20(OH)D3 and 20,23(OH)2D3 act as antagonists or inverse agonists of RORα and RORγ, that opens new possibilities for local (skin) or systemic regulation.-Slominski, A. T., Kim, T.-K., Takeda, Y., Janjetovic, Z., Broz˙yna, A. A., Skobowiat, C., Wang, J., Postlethwaite, A., Li, W., Tuckey, R. C., Jetten, A. M. RORα and ROR γ are expressed in human skin and serve as receptors for endogenously produced noncalcemic 20-hydroxy- and 20,23-dihydroxyvitamin D.

In vivo deletion of CAR resulted in high bone mass phenotypes in male mice.

Constitutive androstane receptor (CAR) was originally identified as xenobiotic sensor that regulates the expression of cytochrome P450 genes. However, recent studies suggest that this nuclear receptor is also involved in the regulation of energy metabolism including glucose and lipid homeostasis. This study investigated the role of CAR in the regulation of bone mass in vivo using CAR(-/-) mice. Endogenous mRNA expression of CAR was observed in both primary osteoblasts and osteoclast precursors. CAR(-/-) mice have exhibited significant increase in whole body bone mineral density (BMD) by 9.5% (P < 0.01) and 5.5% (P < 0.05) at 10 and 15 weeks of age, respectively, compared with WT mice in males. Microcomputed tomography analysis of proximal tibia demonstrated a significant increase in trabecular bone volume (62.7%), trabecular number (54.1%) in male CAR(-/-) mice compared with WT mice. However, primary culture of calvarial cells exhibited no significant changes in osteogenic differentiation potential between CAR(-/-) and WT. In addition, the number of tartrate-resistant acid-phosphatase positive osteoclasts in the femur and serum level of CTx was not different between CAR(-/-) and WT mice. The higher BMD and microstructural parameters were not observed in female mice. Interestingly, serum level of testosterone in male CAR(-/-) mice was 2.5-fold higher compared with WT mice and the mRNA expressions of Cyp2b9 and 2b10 in the liver, which regulate testosterone metabolism, were significantly down-regulated in male CAR(-/-) mice. Furthermore, the difference in BMD between CAR(-/-) and WT mice disappeared at 8 weeks after performing orchiectomy. CAR(-/-) mice also exhibited significant increase in serum 1,25(OH)2 D3 levels but Cyp 27B1 which converts 25(OH)D3 to 1,25(OH)2 D3 was significantly down-regulated compared to WT mice. These results suggest that in vivo deletion of CAR resulted in higher bone mass, which appears to be a result from reduced metabolism of testosterone due to down-regulation of Cyp2b.

1,25-Dihydroxyvitamin D regulates macrophage activation through FBP1/PKR and ameliorates arthritis in TNF-transgenic mice.

1,25-Dihydroxyvitamin D (1,25(OH)2D3) has immunomodulatory activity and its deficiency correlates with rheumatoid arthritis (RA) incidence. Whether 1,25(OH)2D3 modulates macrophage activation or protects against RA remains unclear. We demonstrate that 1,25(OH)2D3 suppresses M1 macrophage polarization and CD80, IL-6, CXCL10, IFIT1, IFI44, and double-stranded RNA-dependent protein kinase R (PKR) expression in the macrophages of RA patients. In phorbol 12-myristate 13-acetate-induced THP-1 cells, 1,25(OH)2D3 upregulates fructose-1,6-bisphosphatase 1 (FBP1) expression through direct promoter interaction. FBP1 interacts with PKR and promotes PKR ubiquitination degradation. SiR-FBP1 transfection impairs 1,25(OH)2D3 action and suppresses IL-6, CXCL10, IFIT1, IFI27, and IFI44 expression in macrophages, whereas siR-PKR transfection impairs siR-FBP1 activity in 1,25(OH)2D3-treated macrophages. 1,25(OH)2D3 treatment ameliorates the clinical signs of arthritis in tumor necrosis factor-transgenic mice, inhibits M1 polarization and marker expression, and promotes FBP1 expression in mononuclear cells isolated from swollen joints; thus, 1,25(OH)2D3 suppresses M1 macrophage activation through FBP1/PKR and ameliorates arthritis by restoring the macrophage subtype.

Evaluation of the effect and predictive role of vitamin D and vitamin D receptor expression in CD4 + , CD8 + , CD14 + , CD56 + cells on the development of chronic rejection and graft functions in kidney transplant patients.

PURPOSE: It is known that vitamin D has positive effects on graft functions (reduce fibrosis, suppress excessive inflammatory response, improve graft functions). In our study, it was aimed to evaluate the effects and predictive roles of vitamin D, the expression of vitamin D receptor (VDR) in lymphocytes, monocytes, natural killer cells on chronic rejection and graft functions in kidney transplant patients. METHODS: Seventy one people were included in the study and analyses were made by dividing them into 3 groups. Group 1: Healthy control (n = 29), Group 2: Kidney transplant patients with stable kidney function (n = 17), and Group 3: Kidney transplant patients with chronic rejection diagnosis (n = 25). Serum 25-hydroxycholecalciferol, 1.25 dihydroxycholecalciferol levels and VDR percentages in CD4 + , CD8 + , CD14 + , CD56 + cells were measured in 3 groups. ROC analyses and logistic regression models were performed to predict rejection and long-term graft functions. RESULTS: The percentage of VDR expression in CD4 + lymphocytes (p < 0.001) and CD14( +) monocytes (p < 0.001), 25-hydroxycholecalciferol and 1.25 dihydroxycholecalciferol levels were lower in group 3 was detected. In ROC analyses and logistic regression models, VDR expression in CD4( +)T lymphocytes was shown to have a statistically significant value in the development of chronic rejection (Odds ratio 0.86: 0.76-0.92; p = 0.001/AUC = 0.941, p < 0.001) and prediction of 5th-year graft functions (Odds ratio 0.93: 0.88-0.98; p = 0.017/AUC = 0.745, p = 0.007). CONCLUSION: In our study, it was shown that low vitamin D and VDR expression is associated with poor outcome and VDR expression in CD4( +)T lymphocytes is predictive in terms of graft function and rejection.