Microbial bile acid metabolite ameliorates mycophenolate mofetil-induced gastrointestinal toxicity through vitamin D3 receptor.

Mycophenolate mofetil (MMF) is one of the most used immunosuppressive drugs in organ transplantation, but frequent gastrointestinal (GI) side effects through unknown mechanisms limit its clinical use. Gut microbiota and its metabolites were recently reported to play a vital role in MMF-induced GI toxicity, but the specific mechanism of how they interact with the human body is still unclear. Here, we found that secondary bile acids (BAs), as bacterial metabolites, were significantly reduced by MMF administration in the gut of mice. Microbiome data and fecal microbiota transfer model supported a microbiota-dependent effect on the reduction of secondary BAs. Supplementation of the secondary BA lithocholic acid alleviated MMF-induced weight loss, colonic inflammation, and oxidative phosphorylation damage. Genetic deletion of the vitamin D3 receptor (VDR), which serves as a primary colonic BA receptor, in colonic epithelial cells (VDRΔIEC) abolished the therapeutic effect of lithocholic acid on MMF-induced GI toxicity. Impressively, we discovered that paricalcitol, a Food and Drug Administration-approved VDR agonist that has been used in clinics for years, could effectively alleviate MMF-induced GI toxicity. Our study reveals a previously unrecognized mechanism of gut microbiota, BAs, and VDR signaling in MMF-induced GI side effects, offering potential therapeutic strategies for clinics.

Altered vitamin D3 metabolism in the ovary and periovarian adipose tissue of rats with letrozole-induced PCOS.

Vitamin D3 (VD3) plays an important role in the ovary and its deficiency is associated with ovarian pathologies, including polycystic ovary syndrome (PCOS). However, there is no data related to VD3 metabolism in the ovary during PCOS. Herein, we investigated differences in the expression of VD3 receptor (VDR) and key VD3 metabolic enzymes, 1α-hydroxylase (CYP27B1) and 24-hydroxylase (CYP24A1), in the ovary and periovarian adipose tissue (POAT) of control (proestrus and diestrus) and PCOS induced by letrozole rats. Vdr, Cyp27b1 and Cyp24a1 mRNA expression was determined, their protein abundance was examined and immunolocalized. Furthermore, VD3 metabolite concentrations in plasma (25OHD) and tissues (ovary and POAT; 1,25(OH)2D3), and plasma calcium level were determined. 25OHD concentration decreased markedly in letrozole-treated rats in comparison with controls, whereas calcium concentration did not vary among the examined groups. The amount of 1,25(OH)2D3 decreased in both ovary and POAT of PCOS rats. In the ovary, we found decreased Cyp27b1 and increased Vdr mRNA expression in letrozole-treated and diestrus control group. Corresponding protein abundances were down-regulated and up-regulated, respectively but only following letrozole treatment. In POAT, only Cyp27b1 transcript level and CYP27B1 protein abundance were decreased in letrozole-treated rats. VDR was immunolocalized in healthy and cystic follicles, while CYP27B1 and CYP24A1 were found exclusively in healthy ones. Concluding, our results provide the first evidence of disrupted VD3 metabolism in the ovary and POAT of PCOS rats. The reduced 1,25(OH)2D3 concentration in those tissues suggests their contribution to VD3 deficiency observed in PCOS and might implicate in PCOS pathogenesis.

Vitamin D receptor (VDR) expression in different molecular subtypes of canine mammary carcinoma.

BACKGROUND: The molecular-based classification of canine mammary carcinomas (CMCs) has been the focus of much current research. Both in canines and humans, the triple-negative (TN) molecular subtype of mammary cancer is defined by a lack of expression of progesterone receptor (PR), oestrogen receptor (ER) and HER2. It has a poor prognosis; no effective targeted therapy is available. Vitamin D displays anticarcinogenic properties, and the expression of its receptor (VDR) has been found in different molecular subtypes, being about 30-40 % of TN breast cancer (TNBC) positive to it. We assessed the VDR expression in the different molecular subtypes of 58 CMCs from 45 female dogs using an immunohistochemical panel for the molecular classification of included: PR, ER, HER2, cytokeratin (CK) 5, CK14, and Ki67. In addition, we studied the relationship among the molecular subtypes of CMCs and clinicopathologic parameters. RESULTS: Investigation showed VDR positivity in 45.0 % of the triple-negative CMCs (TNCMCs), 27.3 % of luminal B and 19.0 % of luminal A. Luminal A was the most molecular subtype represented of the total tumours (36.2 %), followed of TNCMCs (34.5 %), luminal B (20.7 %) and HER2-overexpression (10.3 %). Both HER2-overexpression and TNCMC subtypes were positively related to lymphatic invasion (P = 0.028), simple histologic subtype (P = 0.007), a higher histological grade (P = 0.045) and a trend to higher proliferation index (P = 0.09). CONCLUSIONS: The highest VDR expression was observed in TNCMC, being almost half of them (45 %) positive to this receptor. VDR expression was absent in HER2-overexpression tumours and low in luminal A and B molecular subtypes.

Vitamin D3 ameliorates podocyte injury through the nephrin signalling pathway.

Renal podocytes form the main filtration barrier possessing unique phenotype maintained by proteins including podocalyxin and nephrin, which are modulated in pathological conditions. In diabetic nephropathy (DN), podocytes become structurally and functionally compromised. Nephrin, a structural backbone protein of the slit diaphragm, acts as regulator of podocyte intracellular signalling with renoprotective role. Vitamin D3 through its receptor, VDR, provides renal protection in DN but limited data exist about its effect on podocytes. In this study, we used isolated rat glomeruli to assess podocalyxin and nephrin expression after treatment with the 1,25-dihydroxyvitamin D3 analogue paricalcitol in the presence of normal and diabetic glucose levels. The role of 1,25-dihydroxyvitamin D3 (calcitriol) and its analogue, paricalcitol, on podocyte morphology and survival was also investigated in the streptozotocin (STZ)-diabetic animal model. In our ex vivo model, glomeruli exhibited high glucose-mediated down-regulation of podocalyxin, and nephrin, while paricalcitol reversed the high glucose-induced decrease of nephrin and podocalyxin expression. Paricalcitol treatment enhanced VDR expression and promoted VDR and RXR co-localization in the nucleus. Our data also indicated that hyperglycaemia impaired survival of cultured glomeruli and suggested that the implemented nephrin down-regulation was reversed by paricalcitol treatment, initiating Akt signal transduction which may be involved in glomerular survival. Our findings were further verified in vivo, as in the STZ-diabetic animal model, calcitriol and paricalcitol treatment resulted in significant amelioration of hyperglycaemia and restoration of nephrin signalling, suggesting that calcitriol and paricalcitol may provide molecular bases for protection against loss of the permselective renal barrier in DN.

Association of rs4516035 Polymorphism with Osteoporosis in the Southeastern Iranian Population: A Case-Control Study.

BACKGROUND: Genetic polymorphisms are known to play a crucial role in the development of osteoporosis. Vitamin D3 regulates bone homeostasis through the vitamin D receptor (VDR). Reduced VDR activity increases osteoporosis risk. Study Design: A case-control study. METHODS: This case-control study investigated the potential association between six single-nucleotide polymorphisms (SNPs) within the VDR gene (rs11568820, rs4516035, rs2228570, rs1544410, rs7975232, and rs731236) and the occurrence of osteoporosis in Kerman province. The genotypes of the SNPs were analyzed using polymerase chain reaction-restriction fragment length polymorphism, tetra primer amplification refractory mutation system-PCR, and sequencing in two groups of osteoporosis patients (n=40) and controls (n=42). Additionally, the levels of calcium and vitamin D3 in the serum of the patients were measured, and the in silico analysis of the VDR structure and interaction was performed using I-TASSER, ProSA, PROCHECK, GeneMANIA, GTEx, and GPS 6.0. RESULTS: None of the patients exhibited calcium or vitamin D3 deficiencies. Among the six SNPs, only the T allele in rs4516035, which leads to a shorter variant called VDRA, showed a significant association with susceptibility to osteoporosis (odds ratio=3.061, P=0.007). The in silico analysis demonstrated that the 3D structure, expression, and post-transcriptional modification of VDRA are distinct from those of the more extended variant, VDRB1. VDRB1 is upregulated in sun-exposed skin, and its interactions with its partners differ from those of VDRA. CONCLUSION: Despite adequate vitamin D levels, the VDRA variant, which has lower activity, could increase the predisposition to osteoporosis in the studied population. These findings clarify the importance of genetic screening for personalized medicine and the effectiveness of prevention and treatment strategies.

Pan-Cancer Analysis Confirms the Prognostic and Immunological Implications of the 1,25-Dihydroxy Vitamin D3 Receptor in Cervical Squamous Cell Carcinoma.

Vitamin D receptor (VDR), specifically the 1,25-dihydroxy form, holds significant importance in various types of cancer, including cervical squamous cell carcinoma (CESC), which poses a significant public health challenge. A pan-cancer analysis was conducted on VDR in CESC, with a focus on its expression and relationship with immune infiltration and genetic alterations. Bioinformatics databases, including TIMER, GEPIA, UALCAN, cBioportal, and Kaplan-Meier Plotter, have been utilized. VDR expression in CESC has been validated using publicly available data. Results were significantly upregulated (P=0.05) in THCA, BRCA, KICH, LUAD, LIHC, STAD, UCEC, CESC, CHOL, ESCA, and HNSC samples. We analyzed the correlation between VDR expression and various clinicopathological factors such as age, race, and cancer stage. VDR expression was significantly upregulated across all age groups, with the highest levels observed in older adults followed by young and middle-aged adults. VDR gene expression was significantly elevated across all races, including Caucasians, African-Americans, and Asians, compared to that in the normal group. Furthermore, VDR expression was significantly upregulated in cancer stages 1, 2, 3, and 4, with the highest increase observed in stage 3 compared to that in normal individuals. We analyzed the expression of the VDR in relation to immune cell type and tumor cell purity in CESC. Our results indicated that VDR expression was positively correlated with neutrophils and dendritic cells and negatively correlated with tumor cell purity in CESC patients. There was no significant correlation between VDR expression and the abundance of B cells, CD8+ T cells, CD4+ T cells, and macrophages. Our study found no significant effect of VDR expression on patient prognosis, although it was positively correlated with CD4+ T cells. The Cox proportional hazards model indicated that age and immune cells did not significantly affect prognosis. Most VDR mutations are concentrated in diffuse large B-cell lymphoma, with an amplification frequency of 4% and a deep deletion frequency of 2.2%. GEO confirmed VDR expression in CESC, identifying 1515 upregulated and 1877 downregulated genes, with volcano plots showing CESC downregulation in patients.

Dissection of an impact of VDR and RXRA on the genomic activity of 1,25(OH)2D3 in A431 squamous cell carcinoma.

BACKGROUND: Human skin is the natural source, place of metabolism, and target for vitamin D3. The classical active form of vitamin D3, 1,25(OH)2D3, expresses pluripotent properties and is intensively studied in cancer prevention and therapy. To define the specific role of vitamin D3 receptor (VDR) and its co-receptor retinoid X receptor alpha (RXRA) in genomic regulation, VDR or RXRA genes were silenced in the squamous cell carcinoma cell line A431 and treated with 1,25(OH)2D3 at long incubation time points 24 h/72 h. Extending the incubation time of A431 WT (wild-type) cells with 1,25(OH)2D3 resulted in a two-fold increase in DEGs (differentially expressed genes) and a change in the amount of downregulated from 37% to 53%. VDR knockout led to a complete loss of 1,25(OH)2D3-induced genome-wide gene regulation at 24 h time point, but after 72 h, 20 DEGs were found, of which 75% were downregulated, and most of them belonged to the gene ontology group "immune response". This may indicate the existence of an alternative, secondary response to 1,25(OH)2D3. In contrast, treatment of A431 ΔRXRA cells with 1,25(OH)2D3 for 24 h only partially affected DEGs, suggesting RXRA-independent regulation. Interestingly, overexpression of classic 1,25(OH)2D3 targets, like CYP24A1 (family 24 of subfamily A of cytochrome P450 member 1) or CAMP (cathelicidin antimicrobial peptide) was found to be RXRA-independent. Also, immunofluorescence staining of A431 WT cells revealed partial VDR/RXRA colocalization after 24 h and 72 h 1,25(OH)2D3 treatment. Comparison of transcriptome changes induced by 1,25(OH)2D3 in normal keratinocytes vs. cancer cells showed high cell type specific expression pattern with only a few genes commonly regulated by 1,25(OH)2D3. Activation of the genomic pathway at least partially reversed the expression of cancer-related genes, forming a basis for anti-cancer activates of 1,25(OH)2D3. In summary, VDR or RXRA independent genomic activities of 1,25(OH)2D3 suggest the involvement of alternative factors, opening new challenges in this field.

Effects of Vitamin D3 Supplementation and Aerobic Training on Autophagy Signaling Proteins in a Rat Model Type 2 Diabetes Induced by High-Fat Diet and Streptozotocin.

The aim of this study was to investigate the combined effects of vitamin D3 supplementation and aerobic training on regulating the autophagy process in rats with type 2 diabetic induced by a high-fat diet and streptozotocin. A total of 40 Wistar rats were divided into five groups: normal control (NC), diabetic control (DC), diabetic + aerobic training (DAT), diabetic + vitamin D3 (DVD), and diabetic + aerobic training + vitamin D3 (DVDAT). The rats underwent eight weeks of aerobic training with an intensity of 60% maximum running speed for one hour, along with weekly subcutaneous injections of 10,000 units of vitamin D3. The protein levels of different autophagy markers were assessed in the left ventricular heart tissue. The results showed that the protein levels of AMPK, pAMPK, mTOR, and pmTOR were significantly lower in the DC group compared to the NC group. Conversely, the levels of ULK, Beclin-1, LC3II, Fyco, and Cathepsin D proteins were significantly higher in the DC group. However, the interventions of aerobic training and vitamin D3 supplementation, either individually or in combination, led to increased levels of AMPK, pAMPK, mTOR, and pmTOR, and decreased levels of ULK, Beclin-1, LC3II, Fyco, and Cathepsin D (p < 0.05). Additionally, the aerobic capacity in the DAT and DVDAT groups was significantly higher compared to the NC, DC, and DVD groups (p < 0.05). These findings suggest that type 2 diabetes is associated with excessive autophagy in the left ventricle. However, after eight weeks of vitamin D3 supplementation and aerobic training, a significant reduction in excessive autophagy was observed in rats with type 2 diabetes.

Vitamin D3 deficiency induced intestinal inflammatory response of turbot through nuclear factor-κB/inflammasome pathway, accompanied by the mutually exclusive apoptosis and autophagy.

Vitamin D3 (VD3) participated widely in the nuclear factor-κB (NF-κB)-mediated inflammation, apoptosis, and autophagy through the vitamin D receptor (VDR). However, the molecular mechanisms remain not understood in teleost. The present study investigated the functions of VD3/VDR on intestinal inflammation, autophagy, and apoptosis of turbot in vivo and in vitro. Triple replicates of 30 fish were fed with each of three diets with graded levels of 32.0 (D0), 1012.6 (D1), and 3978.2 (D2) IU/kg VD3. Obvious intestinal enteritis was observed in the D0 group and followed with dysfunction of intestinal mucosal barriers. The intestinal inflammatory response induced by VD3 deficiency was regulated by the NF-κB/inflammasome signalling. The promotion of intestinal apoptosis and suppression of intestinal autophagy were also observed in the D0 group. Similarly, VD3 deficiency in vitro induced more intense inflammation regulated by NF-κB/inflammasome signalling. The mutually exclusive apoptosis and autophagy were also observed in the group without 1,25(OH)2D3 in vitro, accompanied by similar changes in apoptosis and autophagy increased apoptosis. The gene expression of VDRs was significantly increased with the increasing VD3 supplementation both in vivo and in vitro. Moreover, VDR knockdown in turbot resulted in intestinal inflammation, and this process relied on the activation of inflammasome mediated by NF-κB signalling. Simultaneously, intestinal apoptosis was promoted, whereas intestinal autophagy was inhibited. In conclusion, VD3 deficiency could induce intestinal inflammation via activation of the NF-κB/inflammasome pathway, intestinal apoptosis, and autophagy formed a mutually exclusive relation in teleost. And VDR is the critical molecule in those processes.

Vitamin D in Alzheimer's Disease: Low Levels in Cerebrospinal Fluid Despite Normal Amounts in Serum.

BACKGROUND: Vitamin D insufficiency has been suggested as a dementia risk factor. OBJECTIVE: In this cross-sectional, explorative study we investigated whether levels of vitamin D in cerebrospinal fluid (CSF) are lower in patients with positive biomarkers of Alzheimer's disease (AD) compared to cognitively healthy controls and whether polymorphisms of the vitamin D receptor (VDR) gene, FokI, BsmI, ApaI, and TaqI, are associated with levels of vitamin D in CSF and cognition. METHODS: We included 100 patients≥65 years assessed for cognitive impairment and 76 cognitively healthy controls. Levels of 25-hydroxyvitamin D (25(OH)D) in both serum and CSF, and VDR polymorphisms were analyzed. RESULTS: The mean level of 25(OH)D in serum was 78.6 (SD 28.9) nmol/l. While serum levels of 25(OH)D were not significantly different between the groups, CSF levels of 25(OH)D were significantly lower in patients with positive AD core biomarkers (p = 0.001) compared to patients without such biomarkers. Individuals with the BsmI major homozygote genotype had significantly lower results on a 10-word delayed recall test (p = 0.044) and verbal fluency test (p = 0.013), and individuals with the TaqI major homozygote genotype had significantly lower results on a verbal fluency test (p = 0.030) compared to individuals with the corresponding minor homozygote genotype. CONCLUSION: Patients with positive AD core biomarkers have low CSF levels of 25(OH)D, despite sufficient serum levels. CSF levels of 25(OH)D do not seem to be affected by any of the four VDR gene polymorphisms. TaqI and BsmI major homozygote genotypes might be at increased risk for development of cognitive decline.

MicroRNAs based regulation of cytokine regulating immune expressed genes and their transcription factors in COVID-19.

BACKGROUND: Coronavirus disease 2019 is characterized by the elevation of a broad spectrum of inflammatory mediators associated with poor disease outcomes. We aimed at an in-silico analysis of regulatory microRNA and their transcription factors (TF) for these inflammatory genes that may help to devise potential therapeutic strategies in the future. METHODS: The cytokine regulating immune-expressed genes (CRIEG) were sorted from literature and the GEO microarray dataset. Their co-differentially expressed miRNA and transcription factors were predicted from publicly available databases. Enrichment analysis was done through mienturnet, MiEAA, Gene Ontology, and pathways predicted by KEGG and Reactome pathways. Finally, the functional and regulatory features were analyzed and visualized through Cytoscape. RESULTS: Sixteen CRIEG were observed to have a significant protein-protein interaction network. The ontological analysis revealed significantly enriched pathways for biological processes, molecular functions, and cellular components. The search performed in the miRNA database yielded ten miRNAs that are significantly involved in regulating these genes and their transcription factors. CONCLUSION: An in-silico representation of a network involving miRNAs, CRIEGs, and TF, which take part in the inflammatory response in COVID-19, has been elucidated. Thus, these regulatory factors may have potentially critical roles in the inflammatory response in COVID-19 and may be explored further to develop targeted therapeutic strategies and mechanistic validation.

Therapeutic regulation of autophagy in hepatic metabolism.

Metabolic homeostasis requires dynamic catabolic and anabolic processes. Autophagy, an intracellular lysosomal degradative pathway, can rewire cellular metabolism linking catabolic to anabolic processes and thus sustain homeostasis. This is especially relevant in the liver, a key metabolic organ that governs body energy metabolism. Autophagy's role in hepatic energy regulation has just begun to emerge and autophagy seems to have a much broader impact than what has been appreciated in the field. Though classically known for selective or bulk degradation of cellular components or energy-dense macromolecules, emerging evidence indicates autophagy selectively regulates various signaling proteins to directly impact the expression levels of metabolic enzymes or their upstream regulators. Hence, we review three specific mechanisms by which autophagy can regulate metabolism: A) nutrient regeneration, B) quality control of organelles, and C) signaling protein regulation. The plasticity of the autophagic function is unraveling a new therapeutic approach. Thus, we will also discuss the potential translation of promising preclinical data on autophagy modulation into therapeutic strategies that can be used in the clinic to treat common metabolic disorders.

Genetic Predictors of Early-Onset Spinal Intervertebral Disc Degeneration: Part One of Two.

Intervertebral disc (IVD) degeneration is a progressive and painful pathology that can root from mechanical, biochemical, and environmental stressors. However, recent advancements in biogenetics have now found a predominating genetic influence. Nevertheless, despite these advancements, the pathophysiology of IVD degeneration remains poorly understood. In the first of our two-part series, we will characterize some of the most recent and best-studied genes in the context of intervertebral disc degeneration. We will attempt to formulate the first contemporary gene guide that characterizes the genetic profile of IVD degeneration. The genes of interest include aggrecan (ACAN), matrix metalloproteinase 2 (MMP2), vitamin D receptor (VDR), interleukin 1 alpha (IL1A), and those encoded for collagens such as collagen type XI alpha 1 chain (COL11A1), collagen type I alpha 1 chain (COL1A1), collagen type IX alpha 2 chain (COL9A2), and collagen type IX alpha 3 chain (COL9A3). Genetic analysis studies reveal that these genes play vital roles in maintaining the structural integrity of the intervertebral disc, activating enzymes involved in the extracellular matrix, and promoting connective tissue formation. Nevertheless, characterizing these genes alone is not enough to understand the pathophysiology of IVD degeneration. Therefore, further studies are warranted to understand molecular signalling pathways of IVD degeneration better and ultimately create more sophisticated genetic and cell-based therapies to improve patient outcomes.

COVID-19 Disease and Vitamin D: A Mini-Review.

Novel coronavirus disease (COVID-19) pandemic caused by SARS-CoV-2, for which there is no effective treatment except employing prevention strategies, has already instituted significant number of deaths. In this review, we provide a scientific view on the potential role of vitamin D in SARS-CoV-2 virus/COVID-19 disease. Vitamin D is well-known to play a significant role in maintaining the immune health of an individual. Moreover, it induces antimicrobial peptide expression that can decrease viral replication and regulate the levels of pro-inflammatory/anti-inflammatory cytokines. Therefore, supplementation of vitamin D has the potential to reduce the incidence, severity and the risk of death from pneumonia resulting from the cytokine storm of many viral infections including COVID-19. We suggest that supplementation of subjects at high risk of COVID-19 with vitamin D (1.000 to 3.000 IU) to maintain its optimum serum concentrations may be of significant benefit for both in the prevention and treatment of the COVID-19.

Vitamin D3 signaling and breast cancer: Insights from transgenic mouse models.

The biologically active form of vitamin D3 (1,25(OH)2D) regulates epithelial cell differentiation, proliferation, and apoptosis, lending weight to clinical evidence linking vitamin D3 insufficiency to breast cancer incidence and mortality. Local dysregulation of vitamin D3 metabolism has been identified in patients with breast cancer, implying that disruption of 1,25(OH)2D signaling may contribute to breast cancer development in an autocrine or paracrine manner. Mouse mammary glands express the critical enzymes responsible for 1,25(OH)2D synthesis (Cyp2r1 and Cyp27b1), degradation (Cyp24a1), as well as the vitamin D3 receptor (Vdr), and genetically modified mouse models have revealed a great deal about the role of vitamin D3 in cancer initiation and progression. Ablation of Vdr or Cyp27b1 in murine models of mammary cancer reduces the anti-tumor effects of vitamin D3, while elevation of Cyp24a1 levels increases degradation of 1,25(OH)2D, leading to diminished anti-tumor effects. This review discusses the recent transgenic mouse models of vitamin D3 metabolism and the Vdr signaling network, and how these contribute to mammary gland development, and cancer tumorigenesis and progression. Collectively, these mouse models have helped clarify mechanisms of action of vitamin D3 signaling and suggest that activation or restoration of the vitamin D3 regulated pathway is a potential approach for human breast cancer prevention.

Altered expression of CTLA-4, CD28, VDR, and CD45 mRNA in T cells of patients with Hashimoto's thyroiditis - a pilot study.

INTRODUCTION: CD28/T-cell receptor (TCR)/cytotoxic T-lymphocyte antigen 4 (CTLA4) complex controls T-cell tolerance and autoimmunity in Hashimoto's thyroiditis (HT). In addition, CD45 protein tyrosine phosphatase (PTPase) and vitamin D receptor (VDR) cooperatively interact with the TCR complex to affect autoimmune processes central to the pathogenesis of HT. Nevertheless, their role in HT aetiology has been less well established. In this study, we aimed to explore mRNA expression levels of CTLA4, CD28, CD45, and VDR in T-cells, across different outcomes of HT. MATERIAL AND METHODS: The study included 45 HT patients and 13 euthyroid, healthy controls. T-lymphocytes were isolated from peripheral blood mononuclear cells, total mRNA was extracted from T-cells, and gene expression was studied by reverse transcription-polymerase chain reaction (RT-PCR) and ImageQuant method relative to glyceraldehyde-3-phosphate dehydrogenase RT-PCR products. RESULTS: Nominally higher expression levels of VDR, CTLA4, CD28, and CD45RAB mRNA were found in unsorted T-lymphocytes of healthy controls when compared to the HT patients. No difference was observed between hypothyroid/untreated, spontaneously euthyroid and LT4-treated HT patients. VDR mRNA expression was linked to both T3 levels and CTLA4 gene expression, whilst CD45RB mRNA expression coincided with CTLA4 and CD28 transcript levels. Conversely, older age and lower T3 levels were associated with increased abundance of CD45R0 isoform in HT patients. CONCLUSIONS: The results suggest a cross talk between endocrine and immune functions in HT pathology: an altered peripheral T cell mRNA profile with reduced VDR, CTLA4, CD28, and CD45RAB transcript levels is accompanied by age-related shift from naive to memory/late-differentiated T cell CD45R mRNA signature and associated with thyroid hormone status in the HT patients.

Vitamin D3-dependent VDR signaling delays ron-mediated breast tumorigenesis through suppression of ß-catenin activity.

The Ron receptor is upregulated in human breast cancers and correlates with enhanced metastasis and reduced patient survival. Ron overexpression drives mammary tumorigenesis through direct ß-catenin activation and augmented tumor cell proliferation, migration and invasion. Ron and ß-catenin are also coordinately elevated in breast cancers. The vitamin D receptor (VDR) antagonizes ß-catenin signaling. Herein, we examined mammary tumor onset and progression using a Ron-driven murine model of breast tumorigenesis crossed with VDR deficient mice. VDR ablation accelerated mammary tumor onset and led to tumors that exhibited a desmoplastic phenotype and enhanced metastases. Tumor levels of active ß-catenin were markedly increased in the absence of VDR. In vitro, VDR activation in breast cancer cells reduced ß-catenin activation and transcriptional activity leading to elevated expression of the extracellular Wnt inhibitor dickkopf-related protein 1, and a reduction in the interaction of ß-catenin with the cyclin D1 promoter. Expression of a stabilized form or ß-catenin ablated the protective effects of VDR activation.Collectively, these studies delineate a protective role for VDR signaling in Ron-induced mammary tumorigenesis through disruption of ß-catenin activation.

Normal physiological functions in two animal species with highly different vitamin d status compared to that of humans / Funciones fisiológicas normales en dos especies animales con estatus de vitamina d muy diferentes del actual en seres humanos

Mole rats live in permanent darkness, in networks of underground tunnels (which extend up to 1 km in the subsoil), excavated with their incisors, in warm and semi-arid areas of South Africa. Mole rats have an unusually impoverished vitamin D3 status with undetectable and low plasma concentrations of 25- hydroxyvitamin D3 and 1α,25-dihydroxyvitamin D3, respectively. They express 25-hydroxylase in the liver and 1-hydroxylase and 24-hydroxylase in their kidneys. The presence of specific receptors (VDR) was confirmed in the intestine, kidney, Harderʼs glands and skin. In spite of their poor vitamin D3 status, the apparent fractional intestinal absorption of calcium, magnesium and phosphate was high, always greater than 90%. Oral supplementation with cholecalciferol to mole rats did not improve the efficiency of gastrointestinal absorption of these minerals. Mole ratsdo not display the typical lesion of rickets: hypertrophic and radiolucent growth cartilages. Histological studies reported normal parameters of trabecular and cortical bone quality. Marmosets (monkeys of the New World) are not hypercalcaemic, eventhough they exhibit much higher levels of 25-hydroxyvitamin D3, 1α,25-dihydroxyvitamin D3 and parathyroid hormonethan that of rhesus monkeys and humans. Fed a high vitamin D3 intake (110 IU/day/100 g of body weight), a fraction of the experimental group was found to display osteomalacic changes in their bones: distinct increases in osteoid surface, relative osteoid volume, and active osteoclastic bone resorption. These findings suggest that some marmosets appears to suffer vitamin D-dependent rickets, type II. The maximum binding capacity of the VDR or the dissociation constant of VDR1α,25(OH)2D3 complex of mole rats and New World monkeys are distinctly different of VDR isolated from human cells. Health status of those species appears to be adaptations to the mutations of their VDR. Though rare, as mutations may occur at any time in any patient, the overall message of this review to clinicians may be: recent clinical studies strongly suggests that the normality of physiological functions might be a better indicator of the health status than the serum levels of vitamin D metabolites. (AU)

Las ratas topo viven en la oscuridad permanente, en redes de túneles subterráneos excavadas con sus incisivos (que se extienden hasta 1 km en el subsuelo), en áreas cálidas y semiáridas de Sudáfrica. Las ratas topo tienen un estatus de vitamina D3 inusualmente empobrecido con concentraciones plasmáticas indetectables de 25-hidroxivitamina D3 y bajas de 1α, 25-dihidroxivitamina D3. Poseen 25-hidroxilasa en el hígado y 1-hidroxilasa y 24-hidroxilasa en sus riñones. La presencia de receptores específicos (VDR) ha sido confirmada en el intestino, el riñón, las glándulas de Harder y la piel. A pesar de su pobre estatus de vitamina D3,la absorción fraccional intestinal aparente de calcio, magnesio y fosfato fue alta, siempre superior al 90%. La suplementación oral con colecalciferol a las ratas topo no mejoró la eficacia de la absorción gastrointestinal de estos minerales. No muestran la lesión típica del raquitismo: cartílagos de crecimiento hipertróficos y radiolúcidos. Varios estudios histológicos confirman los hallazgos radiológicos y se informan parámetros normales de la calidad ósea trabecular y cortical. Los titíes (monos del Nuevo Mundo) exhiben calcemias normales con niveles más elevados de 25-hidroxivitamina D3, 1α,25-dihidroxivitamina D3 y hormona paratiroidea que los monos rhesus y los seres humanos. Un tercio de un grupo de titíes alimentados con una alta ingesta de vitamina D3 (110 I/día/100 g de peso corporal) exhibió cambios osteomalácicos en sus huesos: aumento en la superficie osteoide, volumen osteoide y activa reabsorción osteoclástica. Estos hallazgos sugieren que una fracción de la población de titíes padece raquitismo dependiente de vitamina D, tipo II. Debido a mutaciones ocurridas hace millones de años, las máximas capacidades de ligamiento del VDR o los valores de la constante de disociación del complejo VDR-1α,25(OH)2D3 de las ratas topo o monos del Nuevo Mundo son muy diferentes de los verificables en receptores aislados de células humanas actuales. El mensaje de esta revisión a los médicos clínicos podría ser: varios estudios clínicos recientes indican que la normalidad de las funciones fisiológicas de un paciente es un mejor indicador de su salud que los niveles séricos de los metabolitos de la vitamina D. (AU)