Immunomodulatory effects of 25-hydroxyvitamin D3 on monocytic cell differentiation and influence of vitamin D3 polymorphisms in type 1 diabetes

Immunomodulatory actions of vitamin D in various immune-related disorders: a comprehensive review

For many years, vitamin D has been acknowledged for its role in maintaining calcium and phosphate balance. However, in recent years, research has assessed its immunomodulatory role and come up with conflicting conclusions. Because the vitamin D receptor is expressed in a variety of immune cell types, study into the precise role of this molecule in diseases, notably autoimmune disorders, has been made possible. The physiologically activated version of vitamin D also promotes a tolerogenic immunological condition in addition to modulating innate and acquired immune cell responses. According to a number of recent studies, this important micronutrient plays a complex role in numerous biochemical pathways in the immune system and disorders that are associated with them. Research in this field is still relatively new, and some studies claim that patients with severe autoimmune illnesses frequently have vitamin D deficiencies or insufficiencies. This review seeks to clarify the most recent research on vitamin D's immune system-related roles, including the pathophysiology of major disorders.

Vitamin D3 is well Correlated with Anti-Helicobacter pylori Immunoglobulins and could be a well Biomarker for Immunity Competence against the Disease

BACKGROUND

Helicobacter pylori (HPY) provokes gastrointestinal disorders and gastric cancer. We supposed that HPY disrupts the 25-OH-Vitamin-D3 (Vit.D3) absorption. We evaluated the association between Vit.D3 and anti-HPY immunoglobulins (Igs) and the Vit.D3 potency as a predictive biomarker for HPY infection.

MATERIALS AND METHODS

603 patients' raw data were gathered from a private clinical laboratory. Anti-HPY Igs including serum IgG, IgA, and IgM, in addition to HPY-stool antigen, were assessed by the immunoassay methods. Vit.D3 was determined by high-pressure liquid chromatography. Correlations, ordinal comparisons, cutoff points (COP), and odds ratio (OR) were estimated.

RESULTS

The age mean ± standard deviation was 39.83 ± 18.426 for female and 38.82 ± 16.937 for male participants (P = 0.521). Significant correlations existed after age and gender adjustment between Vit.D3 serum levels and the HPY IgG (R = 0.298) and IgA (R = 0.271) but not for IgM (R = -0.103). Approximately, 48% of males and 36% of females had insufficient/deficient Vit.D3 serum levels (male/female OR: 1.65; 1.16-2.33; P = 0.0051). After age and gender adjustment, the best COP of Vit.D3 to predict an HPY IgG-positive patient was Vit.D3 >32.80 ng/mL with 66.23% diagnostic accuracy (DAAC), 30.43% specificity (SPC), and 90.41% sensitivity (SEN). For the HPY IgA, the values were Vit.D3 >37.83 ng/mL, DAAC = 60.45%, SPC = 58.82%, SEN = 64.20%. For HPY IgM, the values were Vit.D3 >37.32 ng/mL, DAAC = 58.97%, SPC = 57.33%, and SEN = 100%.

CONCLUSIONS

Vit.D3 had a good association with anti-HPY Igs and may be a good biomarker for immunity competence against HPY infection if the patient's age and gender are considered when interpreting the laboratory results.

The roles of vitamin D and cathelicidin in type 1 diabetes susceptibility

Type 1 diabetes has an increasingly greater incidence and prevalence with no cure available. Vitamin D supplementation is well documented to reduce the risk of developing type 1 diabetes. Being involved in the modulation of cathelicidin expression, the question whether cathelicidin may be one of the underlying cause arises. Cathelicidin has been implicated in both the development and the protection against type 1 diabetes by mediating the interplay between the gut microbiome, the immune system and β cell function. While its potential on type 1 diabetes treatment seems high, the understanding of its effects is still limited. This review aims to contribute to a more comprehensive understanding of the potential of vitamin D and cathelicidin as adjuvants in type 1 diabetes therapy.

Monocytic Cytokines in Autoimmune Polyglandular Syndrome Type 2 Are Modulated by Vitamin D and HLA-DQ

Context

Autoimmune polyglandular syndrome (APS-2: autoimmune Addison’s disease or type 1 diabetes) is conferred by predisposing HLA molecules, vitamin D deficiency, and heritable susceptibility. Organ destruction is accompanied by cytokine alterations. We addressed the monocytic cytokines of two distinct APS-2 cohorts, effects of vitamin D and HLA DQ risk.

Methods

APS-2 patients (n = 30) and healthy controls (n = 30) were genotyped for HLA DQA1/DQB1 and their CD14+ monocytes stimulated with IL1β and/or 1,25(OH)₂D₃ for 24 h. Immune regulatory molecules (IL-6, IL-10, IL-23A, IL-15, CCL-2, PD-L1), vitamin D pathway gene transcripts (CYP24A1, CYP27B1, VDR), and CD14 were analyzed by enzyme-linked immunosorbent assay and RTqPCR.

Results

Pro-inflammatory CCL-2 was higher in APS-2 patients than in controls (p = 0.001), whereas IL-6 showed a trend – (p = 0.1). In vitro treatment with 1,25(OH)₂D₃ reduced proinflammatory cytokines (IL-6, CCL-2, IL-23A, IL-15) whereas anti-inflammatory cytokines (IL-10 and PD-L1) rose both in APS-type 1 diabetes and APS-Addison´s disease. Patients with adrenal autoimmunity showed a stronger response to vitamin D. Expression of IL-23A and vitamin D pathway genes VDR and CYP27B1 varied by HLA genotype and was lower in healthy individuals with high-risk HLA (p = 0.0025; p = 0.04), while healthy controls with low-risk HLA showed a stronger IL-10 and CD14 expression (p = 0.01; p = 0.03).

Conclusion

1,25(OH)₂D₃ regulates the monocytic response in APS-2 disorders type 1 diabetes or Addison´s disease. The monocytic cytokine profile of individuals carrying HLA high-risk alleles is proinflammatory, enhances polyglandular autoimmunity and can be targeted by vitamin D.

Vitamin D's Effect on Immune Function

Ever since its discovery by Windhaus, the importance of the active metabolite of vitamin D (1,25-dihydroxyvitamin D₃; 1,25-(OH)2D₃) has been ever expanding. In this review, the attention is shifted towards the importance of the extra-skeletal effects of vitamin D, with special emphasis on the immune system. The first hint of the significant role of vitamin D on the immune system was made by the discovery of the presence of the vitamin D receptor on almost all cells of the immune system. In vitro, the overwhelming effect of supra-physiological doses of vitamin D on the individual components of the immune system is very clear. Despite these promising pre-clinical results, the translation of the in vitro observations to solid clinical effects has mostly failed. Nevertheless, the evidence of a link between vitamin D deficiency and adverse outcomes is overwhelming and clearly points towards avoidance of vitamin D deficiency especially in early life.

Combined approach of homology modeling, molecular dynamics, and docking: computer-aided drug discovery

With the continuous development in software, algorithms, and increase in computer speed, the field of computer-aided drug design has been witnessing reduction in the time and cost of the drug designing process. Structure based drug design (SBDD), which is based on the 3D structure of the enzyme, is helping in proposing novel inhibitors. Although a number of crystal structures are available in various repositories, there are various proteins whose experimental crystallization is difficult. In such cases, homology modeling, along with the combined application of MD and docking, helps in establishing a reliable 3D structure that can be used for SBDD. In this review, we have reported recent works, which have employed these three techniques for generating structures and further proposing novel inhibitors, for cytoplasmic proteins, membrane proteins, and metal containing proteins. Also, we have discussed these techniques in brief in terms of the theory involved and the various software employed. Hence, this review can give a brief idea about using these tools specifically for a particular problem.

5-Lipoxygenase (ALOX5): Genetic susceptibility to type 2 diabetes and vitamin D effects on monocytes

The arachidonate 5-lipoxygenase (ALOX5) pathway has been implicated in chronic inflammatory disease which may be influenced by vitamin D due to vitamin D response elements (VDRE). We investigated an ALOX5 polymorphism (rs4987105) in patients with type 2 diabetes (T2D) and the in vitro effects of calcitriol (1,25(OH)₂D₃) on ALOX5 metabolism in monocytes of T2D patients and healthy controls (HC). 533 T2D and 473 HC were genotyped for the rs4987105 polymorphism. In addition, the 25(OH)D₃ and 1,25(OH)₂D₃ plasma levels were measured in both cohorts. Further C-reactive protein (CRP) was determined in T2D patients. Our results demonstrate, that genotype CC and the allele C of ALOX5 rs4987105 polymorphism were more frequent in T2D compared to HC (OR = 1.44; 95% CI: 1.12-1.84; p < 0.05). Lower levels of both vitamin D metabolites (p < 0.0001 respectively) were found in the CC genotyped T2D patients compared to CC genotyped HC. In addition, CC genotyped T2D patients had higher levels of CRP compared to CT and TT genotyped T2D patients, (p < 0.01). In order to evaluate the impact of calcitriol in primary isolated monocytes, we isolated monocytes of 20 T2D patients and 20 HC. The cells were treated with 1,25(OH)₂D₃ and interleukin-1beta (IL-1β) for 24 h. The following genes were analysed for expression changes: ALOX5, leukotriene A4 hydrolase (LTA4H), leukotriene B4 receptor type 1 (LTB4R1) and CD14. Treatment with IL-1β+1,25(OH)₂D₃ increased ALOX5, LTA4H and LTB4R1 and CD14 mRNA in both T2D patients and HC (p < 0.0001, respectively). In addition, IL-1β+1,25(OH)₂D₃ treatment led to higher ALOX5, LTA4H and CD14 mRNA levels in T2D patients compared to HC (p < 0.001, p < 0.05, p ≤ 0.05, respectively). In conclusion, ALOX5 rs4987105 allele C confers susceptibility to T2D, lower vitamin D metabolites and higher CRP levels complement this association. Additionally, IL-1β+1,25(OH)₂D₃ treatment on, ALOX5, LTA4H and CD14 mRNA indicate a diabetes specific modulation. These findings identify a novel pathway in T2D potentially amenable for individualized therapeutic targeting.

In silico identification and screening of CYP24A1 inhibitors: 3D QSAR pharmacophore mapping and molecular dynamics analysis

Vitamin D is a key signalling molecule that plays a vital role in the regulation of calcium phosphate homeostasis and bone remodelling. The circulating biologically active form of vitamin D is regulated by the catabolic mechanism of cytochrome P450 24-hydroxylase (CYP24A1) enzyme. The over-expression of CYP24A1 negatively regulates the vitamin D level, which is the causative agent of chronic kidney disease, osteoporosis and several types of cancers. In this study, we found three potential lead molecules adverse to CYP24A1 through structure-based, atom-based pharmacophore and e-pharmacophore-based screening methods. Analysis was done by bioinformatics methods and tools like binding affinity (binding free energy), chemical reactivity (DFT studies) and molecular dynamics simulation (protein-ligand stability). Combined computational investigation showed that the compounds NCI_95001, NCI_382818 and UNPD_141613 may have inhibitory effects against the CYP24A1 protein.

PTPN22 and CTLA-4 Polymorphisms Are Associated With Polyglandular Autoimmunity

CONTEXT

Single nucleotide polymorphisms (SNPs) of various genes increase susceptibility to monoglandular autoimmunity. Data on autoimmune polyglandular syndromes (APSs) are scarce.

OBJECTIVE

Evaluate potential associations of eight SNPs with APSs.

SETTING

Academic referral endocrine clinic.

PATIENTS

A total of 543 patients with APS and monoglandular autoimmunity and controls.

INTERVENTION

The SNP protein tyrosine phosphatase nonreceptor type 22 (PTPN22) rs2476601 (+1858); cytotoxic T-lymphocyte‒associated antigen 4 (CTLA-4) rs3087243 (CT60) and rs231775 (AG49); vitamin D receptor (VDR) rs1544410 (Bsm I), rs7975232 (Apa I), rs731236 (Taq I); tumor necrosis factor α rs1800630 (-863); and interleukin-2 receptor alpha rs10795791 were tested by single-base extension in all subjects.

RESULTS

The PTPN22 +1858 allele and genotype distribution were markedly different between APS, type 1 diabetes [T1D; odds ratio (OR): 2.67; 95% confidence interval (CI): 1.52 to 4.68; P = 0.001], Graves disease (GD; OR: 1.94; 95% CI: 1.16 to 3.25; P = 0.011), and controls (OR: 3.31, 95% CI: 1.82 to 6.02; P < 0.001). T-allele carriers' risk for APS was increased (OR: 3.76; 95% CI: 1.97 to 7.14; P < 0.001). T-allele frequency was higher among APS than controls (OR: 3.25; 95% CI: 1.82 to 5.82; P < 0.001), T1D (OR: 2.54; 95% CI: 1.48 to 4.36; P = 0.001), or GD (OR: 1.89; 95% CI: 1.15 to 3.11; P = 0.012). The SNP CTLA-4 CT60 G-allele carriers were more frequent in APS (85%) than controls (78%) (OR: 1.55; 95% CI: 0.81 to 2.99). Combined analysis of CTLA-4 AG49 and CT60 revealed OR 4.89; 95% CI: 1.86 to13.59; P = 0.00018 of the genotype combination AG/GG for APS vs controls. VDR polymorphisms Bsm I, Apa I, and Taq I did not, but the haplotypes differed between APS and controls (P = 0.0011).

CONCLUSIONS

PTPN22 and CTLA-4 polymorphisms are associated with APS and differentiate between polyglandular and monoglandular autoimmunity.

Genetic polymorphisms of vitamin D3 metabolizing CYP24A1 and CYP2R1 enzymes in Turkish patients with ischemic stroke

Objective Vitamin D deficiency is known as an important risk factor in pathogenesis of atherosclerosis, which contributes to stroke development. Genetic variations including single nucleotide polymorphisms (SNPs) in enzymes involved in vitamin D metabolism can affect susceptibility to the development of stroke. Therefore, the objective of this study was to investigate the association between polymorphisms of vitamin D metabolizing enzymes (rs927650 SNP in CYP24A1, and rs10741657 SNP in CYP2R1 genes,) and ischemic stroke risk in Turkish population. Materials and methods To test this hypothesis, we designed a case-control study which consisted of 256 ischemic stroke patients and 132 controls. Genotypes were determined by PCR-RFLP technique. Results No significant differences were found between patients and controls in terms of CYP24A1 rs927650 and CYP2R1 rs10741657 genotype frequencies. Polymorphic allele frequencies of CYP24A1 rs927650 and CYP2R1 rs10741657 were 0.414 and 0.660 in stroke patients, respectively. Conclusion This is the first study conducted regarding the association of CYP24A1 rs927650 and CYP2R1 rs10741657 genetic polymorphisms and ischemic stroke risk. The polymorphic genotypes of these polymorphisms, together with hypertension, diabetes, smoking, and obesity, were found as significant risk factors for ischemic stroke.

High-dose vitamin D in Addison's disease regulates T-cells and monocytes: A pilot trial

OBJECTIVES

On the basis of the immunomodulatory actions of vitamin D (VD), we investigated the effects of high-dose VD therapy over a 3 mo period on the immune response in patients with Addison's disease (AD).

METHODS

This randomized, controlled, crossover trial included 13 patients with AD who received either cholecalciferol (4000 IU/d) for 3 mo followed by 3 mo placebo oil or the sequential alternative placebo followed by verum. Glucocorticoid replacement doses remained stable. The primary outcome measures were changes in 25-hydroxyvitamin D3 (25(OH)D₃) levels and immune cells including T helper cells (Th; CD3⁺CD4⁺), late-activated Th cells (CD3⁺CD4⁺HLA-DR⁺), regulatory T cells (CD3⁺CD4⁺CD25^brightCD127^dim/neg), cytotoxic T cells (Tc; CD3⁺CD8⁺), late-activated Tc cells (CD3⁺CD8⁺HLA-DR⁺), and monocytes. The explorative analysis included the correlation of changes with VD-related gene polymorphisms and 21-hydroxylase antibody titers.

RESULTS

Ten of 13 patients (77%) were VD deficient. Median 25(OH)D₃ concentrations increased significantly to 41.5 ng/ml (median changes: 19.95 ng/ml; P = 0.0005) after 3 mo of cholecalciferol treatment. Within the T-cells, only the late-activated Th (median changes: 1.6%; P = 0.02) and late-activated Tc cells (median changes: 4.05%; P = 0.03) decreased, whereas monocytes (median changes: 1.05%; P = 0.008) increased after VD therapy. T-cell changes were associated with two polymorphisms (CYP27B1-rs108770012 and VDR-rs10735810), but no changes in the 21-hydroxylase antibody titers were observed.

CONCLUSIONS

Three months of treatment with cholecalciferol achieved sufficient 25(OH)D₃ levels and can regulate late-activated T-cells and monocytes in patients with AD. Explorative analysis revealed potential genetic contributions. This pilot trial provides novel insights about immunomodulation in AD.

Inherited Variation in Vitamin D Genes and Type 1 Diabetes Predisposition

The etiology and pathophysiology of type 1 diabetes remain largely elusive with no established concepts for a causal therapy. Efforts to clarify genetic susceptibility and screening for environmental factors have identified the vitamin D system as a contributory pathway that is potentially correctable. This review aims at compiling all genetic studies addressing the vitamin D system in type 1 diabetes. Herein, association studies with case control cohorts are presented as well as family investigations with transmission tests, meta-analyses and intervention trials. Additionally, rare examples of inborn errors of vitamin D metabolism manifesting with type 1 diabetes and their immune status are discussed. We find a majority of association studies confirming a predisposing role for vitamin D receptor (VDR) polymorphisms and those of the vitamin D metabolism, particularly the CYP27B1 gene encoding the main enzyme for vitamin D activation. Associations, however, are tenuous in relation to the ethnic background of the studied populations. Intervention trials identify the specific requirements of adequate vitamin D doses to achieve vitamin D sufficiency. Preliminary evidence suggests that doses may need to be individualized in order to achieve target effects due to pharmacogenomic variation.

T-lymphocyte and glycemic status after vitamin D treatment in type 1 diabetes: A randomized controlled trial with sequential crossover

BACKGROUND

Type 1 diabetes mellitus (T1D) is mediated by autoaggressive T effector cells with an underlying regulatory T-cell (Treg) defect. Vitamin D deficiency is highly prevalent in T1D, which can aggravate immune dysfunction. High-dose vitamin D treatment may enhance Tregs and improve metabolism in T1D patients.

METHODS

In a randomized double-blind placebo-controlled trial with crossover design, patients received either for 3 months cholecalciferol 4000 IU/d followed by 3 months placebo or the sequential alternative. Thirty-nine T1D patients (19 women and 20 men) completed the trial.

RESULTS

Primary outcome was a change of Tregs, secondary HbA1C, and insulin demand. Effects were evaluated based on intra-individual changes between treatment and placebo periods for outcome measures. Exploratory analyses included vitamin D system variant genotyping and C-peptide measurements. Median 25(OH)D₃ increased to 38.8 ng/ml with males showing a significantly stronger increase (p = .003). T-lymphocyte profiles did not change significantly (p > 2); however, the intra-individual change of Tregs between males and females was different with a significantly stronger increase in men (p = .017), as well as between genotypes of the vitamin D receptor (Apa, Taq, and Bsm: genotypes aa, TT, and bb; p = .004-0.015). Insulin demands declined significantly (p = .003-.039) and HbA1C improved (p < .001). Random C-peptide levels were low but rising (median, 0.125 ng/ml; range, 0.02-0.3) in 6 patients. No toxicity was observed.

CONCLUSION

A daily vitamin D dose of 4000 IU for 3 months was well tolerated and enhanced Tregs in males. Glucometabolic control improved in all. Subsequent larger trials need to address ß-cell function and genotyping for individualized vitamin D doses.

Are low sun exposure and/or vitamin D risk factors for type 1 diabetes?

Ultraviolet radiation and vitamin D, with their known immunosuppressive effects, have the potential to delay or inhibit type 1 diabetes.

Vitamin D3 supplementation alleviates rotavirus infection in pigs and IPEC-J2 cells via regulating the autophagy signaling pathway

Vitamin D had an anti-infection effect and benefited to the intestinal health. Autophagy signaling pathway was regulated by vitamin D3 to inhibit the infection of human immunodeficiency virus type-1. Rotavirus (RV) was a major cause of the severe diarrheal disease in young children and young animals. Although evidence suggested that vitamin D3 attenuates the negative effects of RV infection via the retinoic acid-inducible gene I signaling pathway, little is known of its antiviral effect whether through the regulation of autophagy. The present study was performed to investigate whether vitamin D3 alleviates RV infection in pig and porcine small intestinal epithelial cell line (IPEC-J2) models via regulating the autophagy signaling pathway. RV administration increased the Beclin 1 mRNA abundance in porcine jejunum and ileum. 5000 IU/kg dietary vitamin D3 supplementation greatly up-regulated LC3-II/LC3-I ratios and PR-39 mRNA expression under the condition of RV challenged. The viability of IPEC-J2 was significantly inhibited by RV infection. Incubation with 25-hydroxyvitamin D3 significantly decreased the concentrations of RV antigen and non-structural protein 4 (NSP4), and up-regulated the mRNA expression of Beclin 1 and PR-39 in the RV-infected IPEC-J2 cells. And then, based on the 25-hydroxyvitamin D3 treatment and RV infection, LC3-II mRNA expression in cells was inhibited by an autophagy inhibitor 3-methyladenine (3-MA). Bafilomycin A1 (Baf A1, a class of inhibitors of membrane ATPases, inhibits maturation of autophagic vacuoles) treatment numerically enhanced the LC3-II mRNA abundance, but had no effect on NSP4 concentration. Furthermore, 25-hydroxyvitamin D3 decreased the p62 mRNA expression and increased porcine cathelicidins (PMAP23, PG1-5 and PR-39) mRNA expression in the RV-infected cells. Taken together, these results indicated that vitamin D3 attenuates RV infection through regulating autophagic maturation and porcine cathelicidin genes expression.

Vitamin D induces autophagy of pancreatic β-cells and enhances insulin secretion

Epidemiological evidence indicates that vitamin D is involved in defense against diabetes; however, the precise underlying mechanism remains to be elucidated. In the present study, the effect of vitamin D on the pathogenesis of diabetes was investigated, with an emphasis on its direct effect on pancreatic β‑cells. A streptozotocin (STZ)‑induced type 1 diabetes mellitus (T1DM) mouse model and MIN6 mouse insulinoma β‑cells were subjected to vitamin D treatment. Histopathological analysis of pancreatic islets was performed to investigate insulitis, and reverse transcription-quantitative polymerase chain reaction and western blotting were used to determine the mRNA and protein expression levels of markers of autophagy [microtubule-associated protein 1A/1B‑light chain 3 (LC3) and Beclin 1] and regulation of apoptosis [B-cell lymphoma 2 (Bcl-2)]. Apoptosis of MIN6 cells was examined by flow cytometry following annexin V/propidium iodide labeling. The secretion of insulin was measured by ELISA. The results revealed that vitamin D reduced the incidence of T1DM, enhanced insulin secretion and relieved pancreatic inflammation in STZ‑treated mice. Furthermore, vitamin D increased the mRNA expression levels of LC3 and Beclin 1, and increased Bcl‑2 protein expression levels in STZ‑treated MIN6 cells, while decreasing the apoptosis rate. The results of the present study demonstrated, for the first time to the best of our knowledge, that vitamin D induces autophagy and suppresses apoptosis of pancreatic β‑cells, as well as preventing insulitis. These findings regarding vitamin D provide insights into its involvement in diabetes, and suggest a potential novel strategy for the treatment of diabetes via agents enhancing autophagy in pancreatic β-cells.

Vitamin D treatment for connective tissue diseases: hope beyond the hype?

The prevalence of vitamin D deficiency is increased among patients with CTDs. The active form of vitamin D (calcitriol) is a potent regulator of the immune system and may suppress inflammatory responses. This has led to claims that vitamin D may be a safe treatment, or a treatment adjunct, to reduce systemic inflammation in this patient population. It is important to note, however, that there is insufficient evidence from robust clinical trials to support these novel uses for vitamin D. In this review we examine the potential role of vitamin D as a treatment adjunct for CTDs. We will discuss how vitamin D may modulate the immune response and review the current evidence for using vitamin D to treat CTDs and their associated co-morbidities. We conclude that while there is much excitement about vitamin D in this context, further well-designed trials are needed to demonstrate its efficacy in the treatment of patients with CTDs.

1,25-Dihydroxyvitamin D increases the gene expression of enzymes protecting from glucolipotoxicity in peripheral blood mononuclear cells and human primary endothelial cells

Besides its classical function as an orchestrator of calcium and phosphorus homeostasis, vitamin D also affects insulin secretion and tissue efficiency. A number of studies have consistently reported the inverse relationship between vitamin D deficiency and type 2 diabetes. Activation of certain metabolic pathways and down-stream transcription factors may protect from glucolipotoxicity and their targeted activation -e.g. by vitamin D - might explain the detrimental role of vitamin D deficiency in diabetes. The aim of the study was to quantify gene and protein expression of selected enzymes involved in the protection from glucolipotoxicity, specifically glyoxalase 1 (GLO1), and other enzymes with antioxidant activity - hemoxygenase (HMOX), thiamin pyrophosphokinase (TPK1) and transketolase (TKT), under normo- and hyperglycemic conditions and upon addition of vitamin D in peripheral blood mononuclear cells (PBMCs) and human umbilical vein endothelial cells (HUVEC). The results of our study indicate that the active form of vitamin D regulates gene expression of enzymes opposing the harmful effect of glucolipotoxicity whose activities appear to be suppressed by hyperglycemia. However, we were unable to confirm this effect on protein expression. While we cannot speculate on the effect of vitamin D on diabetes itself our results support its role in the protection against existing glucolipotoxicity therefore possibly translating into the prevention of development of diabetic complications.

Vitamin D—update for the pediatric rheumatologists

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