The genes encoding cytokines IL-2, IL-10 and IL-12B are primary 1alpha,25(OH)2D3 target genes

Transcriptomics identifies blunted immunomodulatory effects of vitamin D in people with multiple sclerosis

Vitamin D deficiency is a risk factor for developing multiple sclerosis (MS). However, the immune effects of vitamin D in people with MS are not well understood. We analyzed transcriptomic datasets generated by RNA sequencing of immune cell subsets (CD4+, CD8+ T cells, B cells, monocytes) from 33 healthy controls and 33 untreated MS cases. We utilized a traditional bioinformatic pipeline and weighted gene co-expression network analysis (WGCNA) to determine genes and pathways correlated with endogenous vitamin D. In controls, CD4+ and CD8+ T cells had 1079 and 1188 genes, respectively, whose expressions were correlated with plasma 25-hydroxyvitamin D level (P < 0.05). Functional enrichment analysis identified association with TNF-alpha and MAPK signaling. In CD4+ T cells of controls, vitamin D level was associated with expression levels of several genes proximal to multiple sclerosis risk loci (P = 0.01). Genes differentially associated with endogenous vitamin D by case-control status were enriched in TNF-alpha signaling via NF-κB. WGCNA suggested a blunted response to vitamin D in cases relative to controls. Collectively, our findings provide further evidence for the immune effects of vitamin D, and demonstrate a differential immune response to vitamin D in cases relative to controls, highlighting a possible mechanism contributing to MS pathophysiology.

The Effect of Vitamin D Consumption on Pro-Inflammatory Cytokines in Athletes: A Systematic Review of Randomized Controlled Trials

Vitamin D is essential for the optimal health of the skeletal system. However, this vitamin also plays a role in other functions of the human body, such as muscle, immune, and inflammatory functions. Some studies have reported that adequate levels of vitamin D improve immune system function by reducing the levels of certain pro-inflammatory cytokines, which can protect against the risk of post-exercise illness. This systematic review aims to investigate the effects of vitamin D supplementation on pro-inflammatory cytokines in athletes. This study was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A literature search was conducted in SPORTDiscus, PubMed, ScienceDirect, and Google Scholar up to 1 October 2023. The quality of the articles was evaluated using the Risk of Bias 2 Tool. After searching the databases, a total of 7417 studies were identified, 6 of which met the eligibility criteria, and their outcomes were presented. The six studies included 176 participants. All six studies are randomized control trials, including a total of 176 subjects, primarily men (81%). Regarding the types of athletes, most participants were endurance athletes. Our investigation in this systematic review demonstrated that out of the six studies, only two of them reported significant changes in IL-6 and TNF-α levels after taking high-dose vitamin D. Other studies did not present any significant changes after vitamin D supplementation in athletes with respect to IL-6 and TNF-α levels. Further studies are needed to determine the effectiveness of vitamin D supplementation for athletes as a disease-prone community.

Enhancing Human Treg Cell Induction through Engineered Dendritic Cells and Zinc Supplementation

Regulatory T (Treg) cells hold promise for the ultimate cure of immune-mediated diseases. However, how to effectively restore Treg function in patients remains unknown. Previous reports suggest that activated dendritic cells (DCs) de novo synthesize locally high concentrations of 1,25-dihydroxy vitamin D, i.e., the active vitamin D or 1,25(OH)2D by upregulating the expression of 25-hydroxy vitamin D 1α-hydroxylase. Although 1,25(OH)2D has been shown to induce Treg cells, DC-derived 1,25(OH)2D only serves as a checkpoint to ensure well-balanced immune responses. Our animal studies have shown that 1,25(OH)2D requires high concentrations to generate Treg cells, which can cause severe side effects. In addition, our animal studies have also demonstrated that dendritic cells (DCs) overexpressing the 1α-hydroxylase de novo synthesize the effective Treg-inducing 1,25(OH)2D concentrations without causing the primary side effect of hypercalcemia (i.e., high blood calcium levels). This study furthers our previous animal studies and explores the efficacy of the la-hydroxylase-overexpressing DCs in inducing human CD4+FOXP3+regulatory T (Treg) cells. We discovered that the effective Treg-inducing doses of 1,25(OH)2D were within a range. Additionally, our data corroborated that the 1α-hydroxylase-overexpressing DCs synthesized 1,25(OH)2D within this concentration range in vivo, thus facilitating effective Treg cell induction. Moreover, this study demonstrated that 1α-hydroxylase expression levels were pivotal for DCs to induce Treg cells because physiological 25(OH)D levels were sufficient for the engineered but not parental DCs to enhance Treg cell induction. Interestingly, adding non-toxic zinc concentrations significantly augmented the Treg-inducing capacity of the engineered DCs. Our new findings offer a novel therapeutic avenue for immune-mediated human diseases, such as inflammatory bowel disease, type 1 diabetes, and multiple sclerosis, by integrating zinc with the 1α-hydroxylase-overexpressing DCs.

Impact of age, hypercholesterolemia, and the vitamin D receptor on brain endogenous β-amyloid peptide accumulation in mice

Age, hypercholesterolemia, and vitamin D deficiency are risk factors that increase the brain accumulation of pathogenic β-amyloid peptides (40 and 42), precursors leading to Alzheimer's disease (AD) in humans. The relative changes accompanying aging, high cholesterol, and/or treatment of calcitriol, active vitamin D receptor (VDR) ligand, under normal physiology are unknown. We examined these relative changes in C57BL/6 mice of ages 2, 4-8, and more than 10 months old, which were fed a normal or high fat / high cholesterol diet and treated with calcitriol, active ligand of the vitamin D receptor (0 or 2.5 μg/kg ×4, intraperitoneally, every other day to elicit cholesterol lowering in liver). Aβ₄₀ but not Aβ₄₂ accumulation in brain and lower P-glycoprotein (P-gp) and neprilysin protein expressions for Aβ efflux and degradation, respectively, were found to be associated with aging. But there was no trend for BACE1 (β-secretase 1, a cholesterol-sensitive enzyme) toward Aβ synthesis with age. In response to calcitriol treatment, P-gp was elevated, mitigating partially the age-related changes. Although age-dependent decreasing trends in mRNA expression levels existed for Cyp46a1, the brain cholesterol processing enzyme, whose inhibition increases BACE1 and ApoE to facilitate microglia Aβ degradation, mRNA changes for other cholesterol transporters: Acat1 and Abca1, and brain cholesterol levels remained unchanged. There was no observable change in the mRNA expression of amyloid precursor protein (APP) and the influx (RAGE) and efflux (LRP1) transporters with respect to age, diet, or calcitriol treatment. Overall, aging poses as a risk factor contributing to Aβ accumulation in brain, and VDR-mediated P-gp activation partially alleviates the outcome.

Effects of Vitamin D and Dexamethasone on Lymphocyte Proportions and Their Associations With Serum Concentrations of 25-Hydroxyvitamin D3 In Vitro in Patients With Multiple Sclerosis or Neuromyelitis Optica Spectrum Disorder

Background

Clear associations have been found between vitamin D deficiency and several autoimmune diseases including multiple sclerosis (MS). However, the benefits of vitamin D supplementation on disease management remain a matter of debate.

Objective and Methods

Patients with MS (N=12) and neuromyelitis optica spectrum disorder (NMOSD; N=12) were enrolled along with 15 healthy controls. Changes in lymphocyte subset proportions during stimulation of their peripheral blood mononuclear cells (PBMCs) with the active form of vitamin D, 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃), and correlations with serum concentrations of the vitamin D precursor 25-hydroxyvitamin D₃ (serum 25(OH)D₃) were explored. The impact of 1,25(OH)₂D₃ stimulation on the expression of vitamin-D-responsive genes in immune cells was also investigated.

Results

In both MS and NMOSD, stimulation of PBMCs with 1,25(OH)₂D₃ followed by steroid suppressed the proliferation of total lymphocytes and T cells. The ratio of CD19⁺CD27⁺ memory B cells (Bmem) to all B cells after stimulation with 1,25(OH)₂D₃ was negatively correlated with serum 25(OH)D₃ in MS (Spearman’s ρ=–0.594, p=0.042), but positively correlated in NMOSD (Pearson’s r = 0.739, p=0.006). However, there was no relationship between the ratio of Bmem to CD19⁺CD24⁺CD38⁺ regulatory B cells and serum 25(OH)D₃ in either MS or NMOSD. In addition, the level of 1,25(OH)₂D₃-induced CYP24A1 mRNA expression in PBMCs was significantly and negatively correlated with serum 25(OH)D₃ (for ΔC_T, r=0.744, p=0.014) in MS.

Conclusion

These findings suggest a beneficial impact of stimulation of PBMCs with vitamin D followed by steroid on the T-cell population. The association between patient serum 25(OH)D₃ and the proportion of Bmem under immune-cell stimulation differed between MS and NMOSD. Further investigations are warranted with larger patient populations.

Vitamin D3 attenuates doxorubicin-induced senescence of human aortic endothelial cells by upregulation of IL-10 via the pAMPKα/Sirt1/Foxo3a signaling pathway

The toxicity of doxorubicin to the cardiovascular system often limits its benefits and widespread use as chemotherapy. The mechanisms involved in doxorubicin-induced cardiovascular damage and possible protective interventions are not well-explored. Using human aortic endothelial cells, we show vitamin D3 strongly attenuates doxorubicin-induced senescence and cell cycle arrest. We further show the protective effects of vitamin D3 are mediated by the upregulation of IL-10 and FOXO3a expression through fine modulation of pAMPKα/SIRT1/FOXO3a complex activity. These results have great significance in finding a target for mitigating doxorubicin-induced cardiovascular toxicity.

Single High-Dose Vitamin D Supplementation as an Approach for Reducing Ultramarathon-Induced Inflammation: A Double-Blind Randomized Controlled Trial

Purpose: A growing number of studies indicate the importance of vitamin D supplementation for sports performance. However, the effects of a single high-dose vitamin D supplementation on ultramarathon-induced inflammation have not been investigated. We here analyzed the effect of a single high-dose vitamin D supplementation on the inflammatory marker levels in ultramarathon runners after an ultramarathon run (maximal run 240 km). Methods: In the study, 35 runners (amateurs) were assigned into two groups: single high-dose vitamin D supplementation group, administered vitamin D (150,000 IU) in vegetable oil 24 h before the start of the run (n = 16); and placebo group (n = 19). Blood was collected for analysis 24 h before, immediately after, and 24 h after the run. Results: Serum 25(OH)D levels were significantly increased after the ultramarathon in both groups. The increase was greater in the vitamin D group than in the control group. Based on post-hoc and other analyses, the increase in interleukin 6 and 10, and resistin levels immediately after the run was significantly higher in runners in the control group than that in those in the supplementation group. Leptin, oncostatin M, and metalloproteinase tissue inhibitor levels were significantly decreased in both groups after the run, regardless of the supplementation. Conclusions: Ultramarathon significantly increases the serum 25(OH)D levels. Attenuation of changes in interleukin levels upon vitamin D supplementation confirmed that vitamin D has anti-inflammatory effect on exercise-induced inflammation.

Vitamin D and Immune Regulation: Antibacterial, Antiviral, Anti-Inflammatory

Regulation of immune function continues to be one of the most well-recognized extraskeletal actions of vitamin D. This stemmed initially from the discovery that antigen presenting cells such as macrophages could actively metabolize precursor 25-hydroxyvitamin D (25D) to active 1,25-dihydroxyvitamin D (1,25D). Parallel observation that activated cells from the immune system expressed the intracellular vitamin D receptor (VDR) for 1,25D suggested a potential role for vitamin D as a localized endogenous modulator of immune function. Subsequent studies have expanded our understanding of how vitamin D exerts effects on both the innate and adaptive arms of the immune system. At an innate level, intracrine synthesis of 1,25D by macrophages and dendritic cells stimulates expression of antimicrobial proteins such as cathelicidin, as well as lowering intracellular iron concentrations via suppression of hepcidin. By potently enhancing autophagy, 1,25D may also play an important role in combatting intracellular pathogens such as M. tuberculosis and viral infections. Local synthesis of 1,25D by macrophages and dendritic cells also appears to play a pivotal role in mediating T-cell responses to vitamin D, leading to suppression of inflammatory T helper (Th)1 and Th17 cells, and concomitant induction of immunotolerogenic T-regulatory responses. The aim of this review is to provide an update on our current understanding of these prominent immune actions of vitamin D, as well as highlighting new, less well-recognized immune effects of vitamin D. The review also aims to place this mechanistic basis for the link between vitamin D and immunity with studies in vivo that have explored a role for vitamin D supplementation as a strategy for improved immune health. This has gained prominence in recent months with the global coronavirus disease 2019 health crisis and highlights important new objectives for future studies of vitamin D and immune function. © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Effects of Vitamin D Supplements on IL-10 and INFγ Levels in Patients with Multiple Sclerosis: a Systematic Review and Meta-Analysis

Background:Vitamin D is one of the considerable environmental factors exhibiting immunomodulatory and anti-inflammatory effects. Objective: To conduct a systematic review and meta-analysis to estimate the effect of vitamin D supplements on IL-10 and INFγ levels in patients with multiple sclerosis. Methods: We searched PubMed, Scopus, EMBASE, CINAHL, Web of Science, Ovid, The Cochrane Library and gray literature, including references of selected studies, conference abstracts which were published up to May 2019. We included single- or double-blinded RCTs or open-label trials in which one of the main outcomes was INFγ and/ or IL-10 levels after vitamin D supplementation. Only articles that had been published in English were included. Results: The literature search yielded 369 articles, that were monitored by us. After eliminating duplicates, 128 studies remained; from these, we excluded observational studies, reviews, case reports and non-randomized trials, and 33 studies remained. Finally, only three articles were included. The mean difference for INFγ was 268.4 and 95 % CI 200.6-336.1. There was no significant heterogeneity (I ² = 0 %, Chi ² = 0.1, p = 0.7). The mean difference for IL-10 was 398.3 and 95% CI -528.05-1324.8). There was significant heterogeneity (I2 = 94 %, Chi2 = 31.1 p < 0.001). Conclusion: The results of this systematic review were not satisfactory. More clinical trials are further needed to evaluate the effects of vitamin D supplements on IL-10 and INFγ levels in patients with multiple sclerosis.

Vitamin D treatment of peripheral blood mononuclear cells modulated immune activation and reduced susceptibility to HIV-1 infection of CD4+ T lymphocytes

INTRODUCTION

Mucosal immune activation, in the context of sexual transmission of HIV-1 infection, is crucial, as the increased presence of activated T cells enhance susceptibility to infection. In this regard, it has been proposed that immunomodulatory compounds capable of modulating immune activation, such as Vitamin D (VitD) may reduce HIV-1 transmission and might be used as a safe and cost-effective strategy for prevention. Considering this, we examined the in vitro effect of the treatment of peripheral blood mononuclear cells (PBMCs) with the active form of VitD, calcitriol, on cellular activation, function and susceptibility of CD4+ T cells to HIV-1 infection.

METHODS

We treated PBMCs from healthy HIV unexposed individuals (Co-HC) and frequently exposed, HIV-1 seronegative individuals (HESNs) from Colombia and from healthy non-exposed individuals from Canada (Ca-HC) with calcitriol and performed in vitro HIV-1 infection assays using X4- and R5-tropic HIV-1 strains respectively. In addition, we evaluated the activation and function of T cells and the expression of viral co-receptors, and select antiviral genes following calcitriol treatment.

RESULTS

Calcitriol reduced the frequency of infected CD4+ T cells and the number of viral particles per cell, for both, X4- and R5-tropic viruses tested in the Co-HC and the Ca-HC, respectively, but not in HESNs. Furthermore, in the Co-HC, calcitriol reduced the frequency of polyclonally activated T cells expressing the activation markers HLA-DR and CD38, and those HLA-DR+CD38-, whereas increased the subpopulation HLA-DR-CD38+. Calcitriol treatment also decreased production of granzyme, IL-2 and MIP-1β by T cells and increased the transcriptional expression of the inhibitor of NF-kB and the antiviral genes cathelicidin (CAMP) and APOBEC3G in PBMCs from Co-HC.

CONCLUSION

Our in vitro findings suggest that VitD treatment could reduce HIV-1 transmission through a specific modulation of the activation levels and function of T cells, and the production of antiviral factors. In conclusion, VitD remains as an interesting potential strategy to prevent HIV-1 transmission that should be further explored.

Effect of Cholecalciferol Supplementation on Treatment Response and IL-10 Level in Vitamin D Deficient Parthenium Dermatitis Patients: A Randomized Double-Blind Placebo-Controlled Trial

Allergic contact dermatitis following exposure to Parthenium is a chronic disease associated with frequent relapses and significant disturbance in the quality of life. The affected patients have lower circulating levels and decreased expression of IL-10. Hence, measures to increase its level may enhance the therapeutic outcome. The clinical trial was undertaken to evaluate the effect of cholecalciferol supplementation on treatment response and IL-10 level in Parthenium dermatitis patients with vitamin D deficiency. A total of 72 patients were recruited and randomized to receive either cholecalciferol tablet 60,000 IU per week or matching placebo for 8 weeks with standard background treatment. Eczema Area Severity Index (EASI) and Dermatology Life Quality Index (DLQI) were assessed at baseline, 4 weeks, and 8 weeks while IL-10 and serum 25-hydroxyvitamin D levels were measured at baseline and 8 weeks. Levels of 25-hydroxyvitamin D and IL-10 showed a significant rise in both placebo and vitamin D groups following the intervention. The relatively higher increase in IL-10 level observed in the vitamin D group was statistically insignificant compared to placebo group. Significant reduction in EASI, as well as DLQI scores, was noted after 1 and 2 months, but the reduction in these scales was not significantly different between the groups. Cholecalciferol supplementation for 2 months did not reduce the disease severity in clinically diagnosed Parthenium dermatitis patients. However, treatment initiation significantly improved plasma IL-10 levels after 2 months in both placebo and cholecalciferol groups.

The dynamic immunomodulatory effects of vitamin D3 during Mycobacterium infection

Mycobacterium tuberculosis ( Mtb), is a highly infectious airborne bacterium. Previous studies have found vitamin D₃ to be a key factor in the defense against Mtb infection, through its regulation of the production of immune-related cytokines, chemokines and effector molecules. Mycobacterium smegmatis was used in our study as a surrogate of Mtb. We hypothesized that the continuous presence of vitamin D₃, as well as the level of severity of infection would differentially modulate host cell immune response in comparison with control and the vehicle, ethanol. We found that vitamin D₃ conditioning promotes increased bacterial clearance during low-level infection, intracellular containment during high-level infection, and minimizes host cytotoxicity. In the presence of vitamin D₃ host cell production of cytokines and effector molecules was infection-level dependent, most notably IL-12, which increased during high-level infection and decreased during low-level infection, and NO, which had a rate of change positively correlated to IL-12. Our study provides evidence that vitamin D₃ modulation is context-dependent and time-variant, as well as highly correlated to level of infection. This study furthers our mechanistic understanding of the dual role of vitamin D₃ as a regulator of bactericidal molecules and protective agent against host cell damage.

Effects of 1α,25 Dihydroxyvitamin D3 on Pro-inflammatory Cytokines of Palmitic Acid Treated Thp-1 Cells

The level of saturated fatty acids, such as palmitic acid (PA), correlates with chronic inflammation in obese and metabolic syndrome patients. However, low level of vitamin D₃ is observed in those conditions. The aim of this study is to investigate effects of 1α,25(OH)₂ D₃ on PA-treated THP-1 cells. Using quantitative real-time polymerase chain reaction, we measure mRNA expression of pro-inflammatory cytokines: TNF-α, Interleukin (IL)-1β, IL-6, and chemokine IL-8 under PA and 1α,25(OH)₂ D₃ influence. PA, at all concentrations (25-100 μM), enhanced LPS stimulatory effect on those mRNA expression compared to LPS-treated and -untreated cells. Combination with 1α,25(OH)₂ D₃ increased cytokine expression at high (10^-6 M) and high-normal (10^-8 M) concentrations compared to PA + LPS and LPS alone, both for 2 and 24 h. However, low-normal (10^-10 M) and low (10^-12 M) levels of 1α,25(OH)₂ D₃ could not enhance PA effect, but mRNA expression of pro-inflammatory cytokine was higher than LPS-treated cells. Upstream pathway of 1α,25(OH)₂ D₃ , which is cholecalciferol, also gave the similar result. Further, inhibition of calcium pathway does not play a role in this mechanism. Thus, these findings support pro-inflammatory effect of PA and vitamin D₃ on innate immune response, especially on fat-induced inflammation.

PRACTICAL APPLICATION

The effect of vitamin D₃ on chronic inflammation in obesity is uncertain. This study shows an in vitro possibility that vitamin D₃ could exaggerate inflammation when combined with high SFAs. The idea of using vitamin D₃ supplement to modulate inflammation in fat-related inflammation needs further refined experiments before its clinical application.

Immune oxysterols: Role in mycobacterial infection and inflammation

Infection remains an important cause of morbidity and mortality. Natural defenses to infection are mediated by intrinsic/innate and adaptive immune responses. While our understanding is considerable it is incomplete and emerging areas of research such as those related to the immune-metabolic axis are only beginning to be appreciated. There is increasing evidence showing a connection between immune signalling and the regulation of sterol and fatty acid metabolism. In particular, metabolic intermediates of cholesterol biosynthesis and its oxidized metabolites (oxysterols) have been shown to regulate adaptive immunity and inflammation and for innate immune signalling to regulate the dynamics of cholesterol synthesis and homeostasis. The side-chain oxidized oxysterols, 25-hydroxycholesterol (25HC) and vitamin D metabolites (vitamin D₃ and vitamin D₂), are now known to impart physiologically profound effects on immune responses. Macrophages play a frontline role in this process connecting immunity, infection and lipid biology, and collaterally are a central target for infection by a wide range of pathogens including viruses and bacteria, especially intracellular bacteria such as mycobacteria. Clinical manifestations of disease severity in the infected host are likely to pay tribute to perturbations of the metabolic-immune phenomena found in lymphocytes and myeloid cells. Historically and consistent with this notion, vitamin D based oxysterols have had a long association with promoting clinical improvements to patients infected with Mycobacterium tuberculosis. Hence understanding the role of early metabolic mediators of inflammatory responses to infection in particular oxysterols, will aid in the development of urgently needed host directed therapeutic and diagnostic design innovation to combat adverse infection outcomes and antibiotic resistance.

Associations of Probiotics with Vitamin D and Leptin Receptors and their Effects on Colon Cancer

Colorectal cancer (CRC) is one of most common causes of cancer-related death worldwide. Recent studies have suggested that microbial and environmental factors including diet and lifestyle can impact on colon cancer development. Vitamin D deficiency and dysfunction of vitamin D receptor (VDR) also correlate with colon cancer. Moreover, leptin, a 16-kDa polypeptide, participates in the regulation of food intake and is associated with other environmental factors affecting colon cancer through the leptin receptor. Altered levels of serum leptin and patterns of expression of its receptor (LPR) may be observed in human colon tumours. Furthermore, the collected data from in vitro and in vivo studies have indicated that consuming probiotic non-pathogenic lactic acid bacteria have beneficial effects on colon cancer. Probiotics, inflammation and vitamin D/VDR have been correlated with leptin and its receptor and are also with colon cancer. Thus, in this paper, we review recent progress on the roles of probiotic, vitamin D/VDR and leptin/LPR in inflammation and colon cancer.

The multiple sclerosis susceptibility genes TAGAP and IL2RA are regulated by vitamin D in CD4+ T cells

Multiple sclerosis (MS) is an inflammatory, demyelinating disorder of the central nervous system that develops in genetically susceptible individuals. The majority of the MS-associated gene variants are located in genetic regions with importance for T-cell differentiation. Vitamin D is a potent immunomodulator, and vitamin D deficiency has been suggested to be associated with increased MS disease susceptibility and activity. In CD4+ T cells, we have analyzed in vitro vitamin D responsiveness of genes that contain an MS-associated single-nucleotide polymorphism (SNP) and with one or more vitamin D response elements in their regulatory regions. We identify IL2RA and TAGAP as novel vitamin D target genes. The vitamin D response is observed in samples from both MS patients and controls, and is not dependent on the genotype of MS-associated SNPs in the respective genes.

The Impact of Vitamin D Levels on Inflammatory Status: A Systematic Review of Immune Cell Studies

Chronic low-grade inflammation accompanies obesity and its related chronic conditions. Both peripheral blood mononuclear cells (PBMCs) and cell lines have been used to study whether vitamin D has immune modulating effects; however, to date a detailed systematic review describing the published evidence has not been completed. We therefore conducted a systematic review on the effect of vitamin D on the protein expression and secretion of inflammatory markers by human-derived immune cells. The review was registered at the International Prospective Register for Systematic Reviews (PROSPERO, Registration number CRD42015023222). A literature search was conducted using Pubmed, Science Direct, Scopus, Web of Science and Medline. The search strategy used the following search terms: Vitamin D or cholecalciferol or 1,25-dihydroxyvitamin or 25-hydroxy-Vitamin D and Inflam* or cytokine* and supplement* or cell*. These terms were searched in the abstract, title and keywords. Inclusion criteria for study selection consisted of human-derived immune cell lines or cellular studies where PBMCs were obtained from humans, reported in the English language, and within the time period of 2000 to 2015. The selection protocol was mapped according to PRISMA guidelines. Twenty three studies (7 cell line and 16 PBMCs studies) met our criteria. All studies selected except one used the active metabolite 1,25(OH)2, with one study using cholecalciferol and two studies also using 25(OH)D. Four out of seven cell line studies showed an anti-inflammatory effect where suppression of key markers such as macrophage chemotactic protein 1, interleukin 6 and interleukin 8 were observed. Fourteen of sixteen PBMC studies also showed a similar anti-inflammatory effect based on common inflammatory endpoints. Mechanisms for such effects included decreased protein expression of toll-like receptor-2 and toll-like receptor-4; lower levels of phosphorylated p38 and p42/42; reduced expression of phosphorylated signal transducer and activator of transcription 5 and decreased reactive oxygen species. This review demonstrates that an anti-inflammatory effect of vitamin D is a consistent observation in studies of cell lines and human derived PBMCs.

The new insight on the regulatory role of the vitamin D3 in metabolic pathways characteristic for cancerogenesis and neurodegenerative diseases

Apart from the classical function of regulating intestinal, bone and kidney calcium and phosphorus absorption as well as bone mineralization, there is growing evidence for the neuroprotective function of vitamin D3 through neuronal calcium regulation, the antioxidative pathway, immunomodulation and detoxification. Vitamin D3 and its derivates influence directly or indirectly almost all metabolic processes such as proliferation, differentiation, apoptosis, inflammatory processes and mutagenesis. Such multifactorial effects of vitamin D3 can be a profitable source of new therapeutic solutions for two radically divergent diseases, cancer and neurodegeneration. Interestingly, an unusual association seems to exist between the occurrence of these two pathological states, called "inverse comorbidity". Patients with cognitive dysfunctions or dementia have considerably lower risk of cancer, whereas survivors of cancer have lower prevalence of central nervous system (CNS) disorders. To our knowledge, there are few publications analyzing the role of vitamin D3 in biological pathways existing in carcinogenic and neuropathological disorders.

Vitamin D, Inflammation, and Colorectal Cancer Progression: A Review of Mechanistic Studies and Future Directions for Epidemiological Studies

Survival from colorectal cancer is positively associated with vitamin D status. However, whether this association is causal remains unclear. Inflammatory processes may link vitamin D to colorectal cancer survival, and therefore investigating inflammatory markers as potential mediators may be a valuable next step. This review starts with an overview of inflammatory processes suggested to be involved in colorectal cancer progression and regulated by vitamin D. Next, we provide recommendations on how to study inflammatory markers in future epidemiologic studies on vitamin D and colorectal cancer survival. Mechanistic studies have shown that calcitriol-active form of vitamin D-influences inflammatory processes involved in cancer progression, including the enzyme cyclooxygenase 2, the NF-κB pathway, and the expression of the cytokines TNFα, IL1β, IL6, IL8, IL17, and TGFβ1. Based on this and taking into account methodologic issues, we recommend to include analysis of specific soluble peptides and proteins, such as cytokines, in future epidemiologic studies on this issue. Vitamin D and the markers should preferably be measured at multiple time points during disease progression or recovery and analyzed using mediation analysis. Including these markers in epidemiologic studies may help answer whether inflammation mediates a causal relationship between vitamin D and colorectal cancer survival.

Low Vitamin D Status Is Associated with Systemic and Gastrointestinal Inflammation in Dogs with a Chronic Enteropathy

Introduction

Vitamin D deficiency, as assessed by serum concentrations of 25 hydroxyvitamin D (25(OH)D), has been linked to the development of over-zealous and inappropriate inflammation in humans. However, the relationship between vitamin D status and inflammation in dogs is ill-defined. Chronic enteropathies (CE) are frequently diagnosed in client owned dogs, have a wide range of serum 25(OH)D concentrations, and represent a spontaneous model in which to probe the relationship between vitamin D and inflammation. The hypothesis of this study was that vitamin D status would be negatively associated with systemic and gastrointestinal inflammation in dogs with a CE. The aim of this study was to examine the relationship between serum 25(OH)D concentrations and markers of systemic and gastrointestinal inflammation in a cohort of dogs with CE.

Methods and Materials

Serum 25(OH)D concentrations, together with neutrophil, monocyte, eosinophil and lymphocyte counts, duodenal histopathology scores, serum IL-2, IL-6, IL-8 and TNFα concentrations and were measured in 39 dogs with histologically confirmed CE. A linear regression model examined the relationship between serum 25(OH)D status and measures of inflammation.

Results

Serum 25(OH)D concentrations were negatively associated with neutrophil and monocyte counts, duodenal histopathology scores and serum IL-2 and IL-8 concentrations. Dogs with low serum 25(OH)D concentrations typically had an inflammatory signature characterised by high monocyte and neutrophil numbers together with low lymphocyte numbers. There is a need to establish whether low vitamin D status is a cause or consequence of inflammation.

Vitamin D as an adjunctive therapy in asthma. Part 1: A review of potential mechanisms

Vitamin D deficiency (VDD) is highly prevalent worldwide. The classical role for vitamin D is to regulate calcium absorption form the gastrointestinal tract and influence bone health. Recently vitamin D receptors and vitamin D metabolic enzymes have been discovered in numerous sites systemically supporting diverse extra-skeletal roles of vitamin D, for example in asthmatic disease. Further, VDD and asthma share several common risk factors including high latitude, winter season, industrialization, poor diet, obesity, and dark skin pigmentation. Vitamin D has been demonstrated to possess potent immunomodulatory effects, including effects on T cells and B cells as well as increasing production of antimicrobial peptides (e.g. cathelicidin). This immunomodulation may lead to asthma specific clinical benefits in terms of decreased bacterial/viral infections, altered airway smooth muscle-remodeling and -function as well as modulation of response to standard anti-asthma therapy (e.g. glucocorticoids and immunotherapy). Thus, vitamin D and its deficiency have a number of biological effects that are potentially important in altering the course of disease pathogenesis and severity in asthma. The purpose of this first of a two-part review is to review potential mechanisms whereby altering vitamin D status may influence asthmatic disease.

Short-term effect of high-dose vitamin D on the level of interleukin 10 in patients with multiple sclerosis: a randomized, double-blind, placebo-controlled clinical trial

BACKGROUND

Multiple sclerosis (MS) is a chronic demyelinating disease of the central nervous system. Vitamin D has been related to the prevention of MS and to modulating its course. Recent studies have shown the safety of high-dose vitamin D in MS.

OBJECTIVE

This study compared the effects of high-dose vitamin D on interleukin 10 (IL-10) levels in MS patients in a double-blind, randomized clinical trial.

METHODS

Ninety-four patients with relapsing remitting MS (RRMS) were randomized into a treatment and a placebo group. Both groups received conventional MS treatment. The intervention group received 50,000 IU of vitamin D every 5 days for 3 months. IL-10 was measured at baseline and after 3 months.

RESULTS

Serum levels of IL-10 were (median ± IQR): 12.58 ± 11.97 and 10.97 ± 9.97 pg/ml in the intervention and placebo groups, respectively, at baseline (p = 0.161); after 3 months, these levels were 13.76 ± 18.95 and 11.31 ± 19.63 pg/ml, respectively (p = 0.158). The IL-10 level increased significantly after receiving high-dose vitamin D for 3 months (β = 0.737, p = 0.015 and R2 = 0.91).

CONCLUSION

IL-10 levels increased significantly in RRMS patients after taking high-dose vitamin D3 for 3 months. High-dose vitamin D might be useful in promoting an anti-inflammatory state in RRMS patients.

Vitamin D receptor signals regulate effector and memory CD8 T cell responses to infections in mice

BACKGROUND

Vitamin D insufficiency is associated with broad-ranging human disease sequelae such as bone disease, cancer, cardiovascular disease, allergy, autoimmune disorders, diabetes, and infectious diseases. Disease risk and severity of a large proportion of the nonskeletal disorders heavily involve the cytotoxic cluster of differentiation (CD) 8 T lymphocyte (CTL) arm of cellular adaptive immunity. Considering the importance of vitamin D in CTL-dependent diseases, there is a critical need for systematic in-depth explorations into the role of vitamin D deficiency in generation and maintenance of CTL immunity during infections and vaccinations.

OBJECTIVE

With the use of wild-type (WT) vitamin D-sufficient mice and the vitamin D receptor knockout (Vdr(-/-)) mouse model of in vivo deficiency of vitamin D signaling, we systematically analyzed the impact of vitamin D deficiency on antigen-specific effector and memory CD8 T cell responses to acute viral and bacterial infections.

METHODS

WT and Vdr(-/-) mice were infected with lymphocytic choriomeningitis virus, a natural mouse pathogen, and antigen-specific CTL responses were analyzed during priming, expansion, contraction, and memory phases. Magnitude, breadth, cytokine production, and localization of antiviral effector and memory CTLs to lymphoid and nonlymphoid tissues were specifically assessed.

RESULTS

The absence of vitamin D signals led to 1) aberrant CD8 T cell effector differentiation (∼2-fold lower granzyme B and reduced B cell lymphoma 2; P ≤ 0.05) and enhanced contraction (∼15% increase; P ≤ 0.05) in antigen-specific CTLs; 2) a significantly restricted (P ≤ 0.05) breadth of the antigen-specific CD8 T cell effector and memory repertoire; and 3) preferential localization of effector (∼2.5-fold increase; P ≤ 0.01) and memory (∼5-fold increase; P ≤ 0.001) CD8 T cells to the lymph nodes compared to nonlymphoid tissues.

CONCLUSION

Our data show a previously unrecognized impact of vitamin D deficiency on the quantity, quality, breadth, and location of CD8 T cell immunity to acute viral and bacterial infections.

Induced differentiation of human myeloid leukemia cells into M2 macrophages by combined treatment with retinoic acid and 1α,25-dihydroxyvitamin D3

Retinoids and 1α,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃) induce differentiation of myeloid leukemia cells into granulocyte and macrophage lineages, respectively. All-trans retinoic acid (ATRA), which is effective in the treatment of acute promyelocytic leukemia, can induce differentiation of other types of myeloid leukemia cells, and combined treatment with retinoid and 1,25(OH)₂D₃ effectively enhances the differentiation of leukemia cells into macrophage-like cells. Recent work has classified macrophages into M1 and M2 types. In this study, we investigated the effect of combined treatment with retinoid and 1,25(OH)₂D₃ on differentiation of myeloid leukemia THP-1 and HL60 cells. 9-cis Retinoic acid (9cRA) plus 1,25(OH)₂D₃ inhibited proliferation of THP-1 and HL60 cells and increased myeloid differentiation markers including nitroblue tetrazolium reducing activity and expression of CD14 and CD11b. ATRA and the synthetic retinoic acid receptor agonist Am80 exhibited similar effects in combination with 1,25(OH)₂D₃ but less effectively than 9cRA, while the retinoid X receptor agonist HX630 was not effective. 9cRA plus 1,25(OH)₂D₃ effectively increased expression of M2 macrophage marker genes, such as CD163, ARG1 and IL10, increased surface CD163 expression, and induced interleukin-10 secretion in myeloid leukemia cells, while 9cRA alone had weaker effects on these phenotypes and 1,25(OH)₂D₃ was not effective. Taken together, our results demonstrate selective induction of M2 macrophage markers in human myeloid leukemia cells by combined treatment with 9cRA and 1,25(OH)₂D₃.

Early pregnancy vitamin D and patterns of antenatal inflammation in African-American women

Vitamin D is essential for the health of both mother and fetus during pregnancy. In the nonpregnant state, vitamin D demonstrates anti-inflammatory effects, but little is known about this relationship during pregnancy. African-American women are at a higher risk of vitamin D deficiency and for altered inflammatory responses during pregnancy. Therefore, we investigated the association of early pregnancy vitamin D nutrition, as assessed by serum 25-hydroxyvitamin D (25-OHD), with second-trimester inflammatory biomarkers (high-sensitivity C-reactive protein, IL-6, IL-10, IL-1β and TNF-α) in 178 pregnant African-American women. Mean serum 25-OHD was 13.4±8.4 ng/ml, and most women (n=147, 82.6%) had inadequate or deficient levels of 25-OHD (<20 ng/ml). Both serum 25-OHD and some inflammatory cytokines (IL-1β and TNF-α) demonstrated significant seasonal variation. In univariate models, log transformed 25-OHD was significantly and inversely associated with log transformed IL-1β (p=0.002) and log transformed IL-6 (p=0.032). After adjusting for covariates, including seasonality, only the inverse association with IL-1β remained statistically significant (p=0.027). Early pregnancy vitamin D nutrition is associated with some inflammatory biomarkers in mid-pregnancy. Additional studies are needed to determine if low vitamin D nutrition is associated with birth outcomes via an inflammatory-mediated pathway.

Vitamin D in inflammatory diseases

Changes in vitamin D serum levels have been associated with inflammatory diseases, such as inflammatory bowel disease (IBD), rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis (MS), atherosclerosis, or asthma. Genome- and transcriptome-wide studies indicate that vitamin D signaling modulates many inflammatory responses on several levels. This includes (i) the regulation of the expression of genes which generate pro-inflammatory mediators, such as cyclooxygenases or 5-lipoxygenase, (ii) the interference with transcription factors, such as NF-κB, which regulate the expression of inflammatory genes and (iii) the activation of signaling cascades, such as MAP kinases which mediate inflammatory responses. Vitamin D targets various tissues and cell types, a number of which belong to the immune system, such as monocytes/macrophages, dendritic cells (DCs) as well as B- and T cells, leading to individual responses of each cell type. One hallmark of these specific vitamin D effects is the cell-type specific regulation of genes involved in the regulation of inflammatory processes and the interplay between vitamin D signaling and other signaling cascades involved in inflammation. An important task in the near future will be the elucidation of the regulatory mechanisms that are involved in the regulation of inflammatory responses by vitamin D on the molecular level by the use of techniques such as chromatin immunoprecipitation (ChIP), ChIP-seq, and FAIRE-seq.

Interaction of vitamin D with membrane-based signaling pathways

Many studies in different biological systems have revealed that 1α,25-dihydroxyvitamin D₃ (1α,25(OH)₂D₃) modulates signaling pathways triggered at the plasma membrane by agents such as Wnt, transforming growth factor (TGF)-β, epidermal growth factor (EGF), and others. In addition, 1α,25(OH)₂D₃ may affect gene expression by paracrine mechanisms that involve the regulation of cytokine or growth factor secretion by neighboring cells. Moreover, post-transcriptional and post-translational effects of 1α,25(OH)₂D₃ add to or overlap with its classical modulation of gene transcription rate. Together, these findings show that vitamin D receptor (VDR) cannot be considered only as a nuclear-acting, ligand-modulated transcription factor that binds to and controls the transcription of target genes. Instead, available data support the view that much of the complex biological activity of 1α,25(OH)₂D₃ resides in its capacity to interact with membrane-based signaling pathways and to modulate the expression and secretion of paracrine factors. Therefore, we propose that future research in the vitamin D field should focus on the interplay between 1α,25(OH)₂D₃ and agents that act at the plasma membrane, and on the analysis of intercellular communication. Global analyses such as RNA-Seq, transcriptomic arrays, and genome-wide ChIP are expected to dissect the interactions at the gene and molecular levels.

Vitamin D in autoimmune liver disease

The development of autoimmune disease is based on the interaction of genetic susceptibility and environmental causes. Environmental factors include infectious and non-infectious agents, with some of these factors being implicated in several autoimmune diseases. Vitamin D is now believed to play a role in the development (or prevention) of several autoimmune diseases, based on its immunomodulatory properties. As well, the increasing incidence of autoimmune disease as one moves away from the equator, may be due to the lack of sunlight, which is crucial for the maintenance of normal vitamin D levels. A deficiency in vitamin D levels or vitamin D receptors is commonly indicated in autoimmune diseases, with multiple sclerosis (MS) being one of the best-studied and well-known examples. However, the role of vitamin D in other autoimmune diseases is not well defined, including autoimmune liver diseases such as primary biliary cirrhosis, autoimmune hepatitis, and primary sclerosing cholangitis. This review will examine the role of vitamin D as an immunomodulator, followed by a comparison of vitamin D in MS versus autoimmune liver disease. From this comparison, it will become clear that vitamin D likely plays a role in the development of autoimmune liver disease, but this area requires further investigation.

Effects of vitamin D on immune disorders with special regard to asthma, COPD and autoimmune diseases: a short review

This paper reviews the recent data on the role of vitamin D (VD) in the genesis of various immunological disorders. It inhibits immune reactions in general, but it enhances the transcription of 'endogenous antibiotics' such as cathelicidin and defensins. VD inhibits the genesis of both Th1- and Th2-cell mediated diseases. The pleiotropic character VD-induced effects are due to the altered transcription of hundreds of genes. VD supplementation in most related studies reduced the prevalence of asthma. Th1-dependent autoimmune diseases (e.g., multiple sclerosis, Type 1 diabetes, Crohn's disease, rheumatoid arthritis and so on) are also inhibited by VD due to inhibition of antigen presentation, reduced polarization of Th0 cells to Th1 cells and reduced production of cytokines from the latter cells. VD seems to also be a useful adjunct in the prevention of allograft rejection. Last but not least, VD supplementation may be useful in the prevention or adjunct treatment of chronic obstructive pulmonary disease.

Schizophrenia: linking prenatal infection to cytokines, the tryptophan catabolite (TRYCAT) pathway, NMDA receptor hypofunction, neurodevelopment and neuroprogression

In 1995, the macrophage-T lymphocyte theory of schizophrenia (Smith and Maes, 1995) considered that activated immuno-inflammatory pathways may account for the higher neurodevelopmental pathology linked with gestational infections through the detrimental effects of activated microglia, oxidative and nitrosative stress (O&NS), cytokine-induced activation of the tryptophan catabolite (TRYCAT) pathway and consequent modulation of the N-methyl d-aspartate receptor (NMDAr) and glutamate production. The aim of the present paper is to review the current state-of-the art regarding the role of the above pathways in schizophrenia. Accumulating data suggest a powerful role for prenatal infection, both viral and microbial, in driving an early developmental etiology to schizophrenia. Models of prenatal rodent infection show maintained activation of immuno-inflammatory pathways coupled to increased microglia activation. The ensuing activation of immuno-inflammatory pathways in schizophrenia may activate the TRYCAT pathway, including increased kynurenic acid (KA) and neurotoxic TRYCATs. Increased KA, via the inhibition of the α7 nicotinic acetylcholine receptor, lowers gamma-amino-butyric-acid (GABA)ergic post-synaptic current, contributing to dysregulated glutamatergic activity. Hypofunctioning of the NMDAr on GABAergic interneurons will contribute to glutamatergic dysregulation. Many susceptibility genes for schizophrenia are predominantly expressed in early development and will interact with these early developmental driven changes in the immuno-inflammatory and TRYCAT pathways. Maternal infection and subsequent immuno-inflammatory responses are additionally associated with O&NS, including lowered antioxidants such as glutathione. This will contribute to alterations in neurogenesis and myelination. In such a scenario a) a genetic or epigenetic potentiation of immuno-inflammatory pathways may constitute a double hit on their own, stimulating wider immuno-inflammatory responses and thus potentiating the TRYCAT pathway and subsequent NMDAr dysfunction and neuroprogression; and b) antipsychotic-induced changes in immuno-inflammatory, TRYCAT and O&NS pathways would modulate the CNS glia-neuronal interactions that determine synaptic plasticity as well as myelin generation and maintenance.

The role of vitamin D in Alzheimer's disease: possible genetic and cell signaling mechanisms

Alzheimer's disease (AD) is the most common form of dementia in the elderly individuals and is associated with progressive memory loss and cognitive dysfunction. A significant association between AD and low levels of vitamin D has been demonstrated. Furthermore, vitamin D supplements appear to have a beneficial clinical effect on AD by regulating micro-RNA, enhancing toll-like receptors, modulating vascular endothelial factor expression, modulating angiogenin, and advanced glycation end products. Vitamin D also exerts its effects on AD by regulating calcium-sensing receptor expression, enhancing amyloid-β peptides clearance, interleukin 10, downregulating matrix metalloproteinases, upregulating heme oxygenase 1, and suppressing the reduced form of nicotinamide adenine dinucleotide phosphate expression. In conclusion, vitamin D may play a beneficial role in AD. Calcitriol is the best vitamin D supplement for AD, because it is the active form of the vitamin D3 metabolite and modulates inflammatory cytokine expression. Therefore, further investigation of the role of calcitriol in AD is needed.

D-livering the message: the importance of vitamin D status in chronic liver disease

Vitamin D is synthesized predominantly in the liver and functions as an important secosteroid hormone with pleiotropic effects. While its key regulatory role in calcium and bone homeostasis is well established, recently there is increasing recognition that vitamin D also regulates cell proliferation and differentiation, and has immunomodulatory, anti-inflammatory and anti-fibrotic properties. These non-skeletal effects are relevant in the pathogenesis and treatment of many causes of chronic liver disease. Vitamin D deficiency is frequently present in chronic liver disease and may predict non-response to antiviral therapy in chronic hepatitis C. Small studies suggest that vitamin D supplementation improves sustained viral response rates, while 1α-hydroxylase polymorphisms and vitamin D-binding protein are also implicated in therapeutic outcomes. Vitamin D deficiency also closely relates to the severity of non-alcoholic fatty liver disease (NAFLD) and is implicated in the pathogenesis of insulin resistance, a key factor in the development of NAFLD. In preclinical studies, phototherapy and vitamin D supplementation ameliorate NAFLD histopathology, while vitamin D is a powerful anti-fibrotic against thioacetamide liver injury. In liver transplant recipients severe vitamin D deficiency predicts, and vitamin D supplementation prevents, acute cellular rejection. The role of vitamin D in the activation and regulation of both innate and adaptive immune systems may explain its importance in the above liver diseases. Further prospective studies are therefore warranted to investigate the therapeutic impact of vitamin D supplementation in chronic liver disease.

The Vitamin D Receptor, Inflammatory Bowel Diseases, and Colon Cancer

The nuclear receptor is an emerging therapeutic target in various human diseases. Vitamin D receptor (VDR), a nuclear receptor, mediates the biological functions of vitamin D. Classically, vitamin D is recognized as an essential contributor to mineral and bone homeostasis. Increasing evidence demonstrates that vitamin D is involved in inflammatory responses. Persistent intestinal inflammation is associated with colon cancer. This review focuses on vitamin D and VDR in inflammatory bowel diseases and colon cancer. We place emphasis on the regulatory roles of vitamin D/VDR on in inflammation, enteric bacteria, and tumorigenesis. We summarize the signaling pathways regulated by VDR in intestinal homeostasis. Finally, we discuss the potential application of the insights gleaned from these findings to personalized therapies in chronic inflammation and colon cancer.

Calcitriol inhibits interleukin-10 expression in cultured human trophoblasts under normal and inflammatory conditions

Preeclampsia is associated with systemic inflammation and increased expression of placental Th1-cytokines. IL-10 and calcitriol inhibit proinflammatory cytokines expression in human placenta helping to fetal allograft toleration. Regulation of placental IL-10 by calcitriol and Th-1 cytokines has not yet been fully elucidated. Since it is believed that calcitriol promotes a shift from a Th1- to a Th2 profile, we hypothesized that it would stimulate IL-10 in a normal and an inflammatory scenario to conjointly restrain inflammation. Therefore, we investigated calcitriol effects upon IL-10 expression in cultured human trophoblasts obtained from normal (NT) and preeclamptic (PE) pregnancies. Similar studies in the presence of TNF-α (as an inflammatory stressor) were also performed. Calcitriol dose-dependently inhibited IL-10 expression in NT, PE and TNF-α-challenged trophoblasts (P<0.05). This effect was prevented by a vitamin D receptor (VDR) antagonist. IL-10 expression was significantly stimulated by TNF-α and IL-1β, inhibited by IFN-γ and was not affected by IL-6. Finally, calcitriol inhibited TNF-α and IL-1β stimulation upon IL-10. In summary, in cultured human trophoblasts, calcitriol down-regulates IL-10 expression under normal as well as under natural and experimental inflammatory conditions. This effect is mediated by the VDR and might involve direct inhibition of TNF-α. In view of these and previous results it seems that in placenta calcitriol suppresses both Th1- and Th2 cytokines while undertakes the anti-inflammatory effects of IL-10 by itself, since both factors exert this task redundantly. The regulation of IL-10 by IFN-γ suggests that this cytokine could be a viable candidate to explain low IL-10 levels in preeclampsia.

The vitamin D receptor gene is associated with Alzheimer's disease

Vitamin D may have a role in brain function. Low levels have been frequently associated with cognitive decline and may contribute to diseases of the nervous system. The vitamin D receptor (VDR) is widely expressed in human brain. Vitamin D appears to be neuroprotective and may regulate inflammation in the brain. We examined two VDR polymorphisms, Apa1 and Taq1. We used DNA from 255 Alzheimer's disease (AD) cases and 260 cognitively screened elderly controls from the longitudinal cohort of the Oxford Project to Investigate Memory and Ageing (OPTIMA). The presence of each of the linked alleles, Apa1 T and Taq1 G, was associated with the risk of AD, particularly in people <75 years old: odds ratios ≥3.0 and p≤0.005. We also found preliminary evidence of interactions associated with AD between these polymorphisms and two other genes involved in the regulation of inflammation, interleukin-10 (IL10) and dopamine β-hydroxylase (DBH): synergy factors ≥3.4, uncorrected p<0.05. These associations are biologically plausible and are consistent with a role for vitamin D in AD. Nevertheless, we consider this to be a hypothesis-generating study, which needs to be replicated in a larger dataset.

Mechanism of 1α,25-dihydroxyvitamin D(3)-dependent repression of interleukin-12B

Interleukin 12 (IL-12) is a heterodimeric, pro-inflammatory cytokine that plays a central role in activation and differentiation of CD4(+) T cells into interferon-γ secreting T-helper type 1 cells. IL-12B, a gene encoding the larger subunit of active IL-12, has been reported to be down-regulated by the nuclear hormone 1α,25-dihydroxyvitamin D(3) (1α,25(OH)(2)D(3)), but the mechanism of the regulation is unknown. In this study, we have examined the molecular mechanism of transcriptional regulation of the IL-12B gene by 1α,25(OH)(2)D(3) in lipopolysaccharide (LPS)-treated human monocytes (THP-1). Quantitative RT-PCR showed that IL-12B mRNA displays a cyclical expression profile and is down-regulated 2.8-fold during the first 8h and even 12.1-fold 24h after exposure to 1α,25(OH)(2)D(3). Gel shift and quantitative chromatin immunoprecipitation (ChIP) assays demonstrated vitamin D receptor (VDR) binding to genomic regions 480 and 6300bp upstream of the IL-12B transcription start site (TSS). Quantitative ChIP assays also revealed that together with VDR and its partner RXR the above regions recruited the co-repressor NCOR2/SMRT and histone deacetylase 3 leading to a decreased histone 4 acetylation and increased histone 3 trimethylation at the IL-12B promoter and its TSS. We suggest that these repressive epigenetic changes eventually cause down-regulation of IL-12 expression. This article is part of a Special Issue entitled: 11th European Symposium on Calcium.

Primary effect of 1α,25(OH)₂D₃ on IL-10 expression in monocytes is short-term down-regulation

The biologically most active vitamin D compound, 1α,25-dihydroxyvitamin D₃ (1α,25(OH)₂D₃), influences the status of inflammation by modulating the expression of several cytokine genes. In this study, we have examined the mechanism of transcriptional regulation of interleukin 10 (IL-10) by 1α,25(OH)₂D₃ in lipopolysaccharide (LPS)-treated human monocytes (THP-1). Quantitative PCR showed that IL-10 mRNA expression was significantly down-regulated (2.8-fold) during the first 8h of 1α,25(OH)₂D₃ treatment, while after 48 h it was up-regulated (3-fold). Gel shift and quantitative chromatin immunoprecipitation (ChIP) assays showed that the vitamin D receptor (VDR) binds in a cyclical fashion to a promoter region 1500-1700 bp upstream of the IL-10 transcription start site (TSS) containing two conserved VDR binding sites. Targeting of VDR binding sites by enhancer specific duplex RNAs revealed that only the more distal element is functional and chromosome conformation capture analysis suggested that this region loops 1α,25(OH)₂D₃-dependently to the TSS. Quantitative ChIP and micrococcal nuclease assays also revealed 1α,25(OH)₂D₃-dependent cyclical epigenetic changes and nucleosome remodeling at this promoter region. In conclusion, in LPS-treated THP-1 cells the primary effect of 1α,25(OH)₂D₃ on IL-10 expression is down-regulation, which is achieved via a cyclical recruitment of VDR to the promoter.