Vitamin D signaling in immune-mediated disorders: Evolving insights and therapeutic opportunities

Vitamin D insufficiency in infants with increased risk of developing type 1 diabetes: a secondary analysis of the POInT Study

BACKGROUND

Vitamin D insufficiency (VDI) may be a factor in the development of type 1 diabetes (T1D). The aim of this study is to investigate the presence and persistence of VDI in a large cohort of infants with increased risk of developing T1D, in light of the differences in local supplementation guidelines.

METHODS

In the POInT Study, a multicentre primary prevention study between February 2018 and March 2021 in Germany, Poland, Belgium, England and Sweden, including infants aged 4-7 months at high genetic risk of developing β-cell autoantibodies, vitamin D levels were analysed at each study visit from inclusion (4-7 months) until 3 years, with an interval of 2 months (first three visits) or 4-6 months (visits 4-8). The protocol actively promotes vitamin D sufficiency to optimise immune tolerance. VDI was defined as a concentration below 30 ng/mL and was treated according to local guidelines of participating centres. Recovery from VDI was defined as a concentration above or equal to 30 ng/mL on the subsequent visit after VDI.

RESULTS

1050 infants were included, of which 5937 vitamin D levels were available for analyses. VDI was observed in 1464 (24.7%) visits and 507 (46.1%) of these were not resolved at the next visit. The risk of having VDI was independently associated with season (higher in winter), weight (higher with increased weight), age (higher with increased age) and country (higher in England). The risk of not recovering from VDI was independently associated with the season of the previously determined VDI, which was higher if VDI was identified in winter.

CONCLUSIONS

VDI is frequent in infants with increased risk of developing T1D. Treatment guidelines for VDI do not seem effective. Increasing supplementation dosages in this patient population seems warranted, especially during winter, and increasing dosages more aggressively after VDI should be considered.

Effects of Vitamin D on Respiratory Function and Immune Status for Patients with Chronic Obstructive Pulmonary Disease (COPD): A Systematic Review and Meta-Analysis

Background

Many studies have demonstrated that vitamin D has clinical benefits when used to treat patients with chronic obstructive pulmonary disease (COPD). However, most of these studies have insufficient samples or inconsistent results. The aim of this meta-analysis was to evaluate the effects of vitamin D therapy in patients with COPD.

Methods

We performed a comprehensive retrieval in the following electronic databases: PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure (CNKI), Wanfang Data, and Chinese Scientific Journals Database (VIP). Two trained reviewers identified relevant studies, extracted data information, and then assessed the methodical quality by the Cochrane risk of bias assessment tool, independently. Then, the meta-analyses were conducted by RevMan 5.4, binary variables were represented by risks ratio (RR), and continuous variables were represented by mean difference (MD) or standardized mean difference (SMD) to assess the efficacy of vitamin D therapy in patients with COPD. Then, publication bias assessment was conducted by funnel plot analysis. Finally, the quality of evidence was assessed by the GRADE system.

Results

A total of 15 articles involving 1598 participants were included in this study. The overall results showed a statistical significance of vitamin D therapy in patients with COPD which can significantly improve forced expiratory volume in 1 second (FEV1) (MD: 5.69, 95% CI: 5.01-6.38,P < 0.00001,I2 = 51%) and FEV1/FVC (SMD:0.49, 95% CI: 0.39-0.60,P < 0.00001,I2 = 84%); and serum 25 (OH)D (SMD:1.21, 95% CI:1.07-1.34,P < 0.00001,I2 = 98%) also increase CD3+ Tcells (MD: 6.67, 95% CI: 5.34-8.00,P < 0.00001,I2 = 78%) and CD4+ T cells (MD: 6.00, 95% CI: 5.01-7.00,P < 0.00001,I2 = 65%); and T lymphocyte CD4+/CD8+ ratio (MD: 0.41, 95% CI: 0.20-0.61,P = 0.0001,I2 = 95%) obviously decrease CD8+ Tcells(SMD: -0.83, 95% CI: -1.05- -0.06,P < 0.00001,I2 = 82%), the times of acute exacerbation (RR: 0.40, 95% CI: 0.28-0.59,P < 0.00001,I2 = 0%), and COPD assessment test (CAT) score (MD: -3.77, 95% CI: -5.86 - -1.68,P = 0.0004,I2 = 79%).

Conclusions

Our analysis indicated that vitamin D used in patients with COPD could improve the lung function (FEV1 and FEV1/FVC), the serum 25(OH)D, CD3+ T cells, CD4 + T cells, and T lymphocyte CD4+/CD8+ ratio and reduce CD8+ T cells, acute exacerbation, and CAT scores.

Epigenetics in Food Allergy and Immunomodulation

Food allergy (FA) is an increasing problem worldwide and, over recent years, its prevalence is rising in developed countries. Nowadays, the immunological and cellular processes that occur in the allergic reactions are not fully understood, which hampers the development of in vitro diagnostic tools and further treatment options. Moreover, allergic diseases could be reinforced by environmental exposure and genetic modifications. Gene expression can be controlled by different epigenetic mechanisms like DNA methylation, histone modifications, and microRNAs. In addition, several environmental factors such as dietary components (vitamin D, butyrate, folic acid) are able to regulate this epigenetic mechanism. All these factors produce modifications in immune genes that could alter the development and function of immune cells, and therefore the etiology of the disease. Furthermore, these epigenetic mechanisms have also an influence on immunomodulation, which could explain sustained responsiveness or unresponsiveness during immunotherapy due to epigenetic modifications in key genes that induce tolerance in several FA. Thus, in this review we focus on the different epigenetic mechanisms that occur in FA and on the influence of several dietary components in these gene modifications.

Circulating Vitamin D levels status and clinical prognostic indices in COVID-19 patients

BACKGROUND

Several immune mechanisms activate in COVID-19 pathogenesis. Usually, coronavirus infection is characterized by dysregulated host immune responses, interleukine-6 increase, hyper-activation of cytotoxic CD8 T lymphocytes. Interestingly, Vitamin D deficiency has been often associated with altered immune responses and infections. In the present study, we evaluated Vitamin D plasma levels in patients affected with different lung involvement during COVID-19 infection.

METHODS

Lymphocyte phenotypes were assessed by flow cytometry. Thoracic CT scan involvement was obtained by an image analysis program.

RESULTS

Vitamin D levels were deficient in (80%) of patients, insufficient in (6.5%) and normal in (13.5%). Patients with very low Vitamin D plasma levels had more elevated D-Dimer values, a more elevated B lymphocyte cell count, a reduction of CD8 + T lymphocytes with a low CD4/CD8 ratio, more compromised clinical findings (measured by LIPI and SOFA scores) and thoracic CT scan involvement.

CONCLUSIONS

Vitamin D deficiency is associated with compromised inflammatory responses and higher pulmonary involvement in COVID-19 affected patients. Vitamin D assessment, during COVID-19 infection, could be a useful analysis for possible therapeutic interventions.

TRIAL REGISTRATION

'retrospectively registered'.

Evaluation of the potential anticancer activity of different vitamin D metabolites on colorectal and breast cancer cell lines

OBJECTIVES

Vitamin D is very important for calcium and mineral metabolism, and many hypotheses appear to link sunlight exposure with cancer risk and prognosis. As many studies supported the antitumor effect of vitamin D we wanted to investigate the potential effect of multiple vitamin D metabolites.

METHODS

This study compared the anticancer effect of three inactive forms of vitamin D₃ which are; cholecalciferol, alfacalcidol, and calcifediol on two human cancer cell lines colorectal cancer (CaCo II) and breast cancer (MCF-7). All were examined after 24, 48, and 72 h continuous exposure using a colorimetric assay (MTT) seeded in 96-multiwell plates. Doxorubicin anticancer used as a standard agent for comparison, while normal skin fibroblast cells (HDFa) was used as our negative control. IC₅₀ values were calculated as indication of antitumor effect.

RESULTS

Broad-spectrum of cytotoxicity with IC₅₀ values ranging from 4 to 200 μM were found. Alfacalcidol was the most potent cytotoxic agents on colorectal cancer (CaCo II) and breast cancer (MCF-7) compared to cholecalciferol, and calcifediol. Both, alfacalcidol and calcifediol were more cytotoxic than cholecalciferol on the tested cell lines as they are partially active metabolites. Breast cancer (MCF-7) was the most sensitive to all metabolites at all-time intervals with the best IC₅₀ values of 4.35 μM ± 1.06 after 72 h continuous exposure of alfacalcidol.

CONCLUSIONS

Vitamin D metabolites are a potential option for cancer treatment along with or an alternative to chemo-therapeutics although extensive preclinical studies are required to prove this effect.

Vitamin D and its therapeutic relevance in pulmonary diseases

Vitamin D is customarily involved in maintaining bone and calcium homeostasis. However, contemporary studies have identified the implication of vitamin D in several cellular processes including cellular proliferation, differentiation, wound healing, repair and regulatory systems inclusive of host defence, immunity, and inflammation. Multiple studies have indicated corelations between low serum levels of vitamin D, perturbed pulmonary functions and enhanced incidences of inflammatory diseases. Almost all of the pulmonary diseases including acute lung injury, cystic fibrosis, asthma, COPD, Pneumonia and Tuberculosis, all are inflammatory in nature. Studies have displayed strong inter-relations with vitamin D deficiency and progression of lung disorders; however, the underlying mechanism is still unknown. Vitamin D has emerged to possess inhibiting effects on pulmonary inflammation while exaggerating innate immune defenses by strongly influencing functions of inflammatory cells including dendritic cells, monocyte/macrophages, T cells, and B cells along with structural epithelial cells. This review dissects the effects of vitamin D on the inflammatory cells and their therapeutic relevance in pulmonary diseases. Although, the data obtained is very limited and needs further corroboration but presents an exciting area of further research. This is because of its ease of supplementation and development of personalized medicine which could lead us to an effective adjunct and cost-effective method of therapeutic modality for highly fatal pulmonary diseases.

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.

Allergic and Immunologic Perspectives of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic immune-mediated inflammatory condition primarily involving the gastrointestinal tract. It includes Crohn's disease (CD), ulcerative colitis (UC), and a less common phenotype-indeterminate colitis. It is thought to result from a complex interplay of environmental, microbial, and host factors including genetic factors, although the exact mechanism is not known. Dietary factors have been shown to play a role in the pathogenesis of IBD and can potentially alter the intestinal microbiota as well as disrupt the immune function in the gut. CD is characterized by transmural inflammation, sometimes associated with granulomatous lesions, and involves the entire gastrointestinal tract but often spares the rectum. UC is characterized by mucosal inflammation typically confined to the colon and rectum. Although IBD is mostly seen in western world, recent data suggests that the incidence and prevalence are increasing worldwide. Enteral nutrition has been shown to be effective in inducing remission in pediatric population with CD; however, there is mixed data in adult population. Nutritional deficiencies such as vitamin D and zinc deficiency are often noted in IBD patients. Several extraintestinal manifestations are noted in patients with IBD. Some of them parallel with the disease activity and others are independent of the disease course. Assessment of IBD disease activity clinically, radiologically, if indicated, biochemically and endoscopically is important to guide therapy in IBD. To ensure comprehensive care, it is important to assess associated conditions such as nutritional and psychological well-being, as well as age appropriate health maintenance status prior to starting treatment for IBD. Several biologic agents including anti-tumor necrosis factor alpha (anti-TNF-α) drugs, anti-integrins, and antibodies to the p40 subunit of IL12/23 are approved for induction and maintenance of remission of IBD. Steroids are also often used for induction. Anti-metabolites and thiopurines are also useful either as monotherapy or in combination regimens. Potential side effects of anti-TNF-α drugs such as serious infections, malignancy, worsening of heart failure, and infusion-related reactions should be considered prior to starting these drugs. Anti-TNF-α drugs with or without immunomodulators (azathioprine, 6-mercaptopurine, methotrexate) are often used for the induction and maintenance of remission. Treating to target of endoscopic and clinical remission provides the best long-term outcomes. Our knowledge and understanding of IBD has grown significantly. However, there are several unanswered questions on pathogenesis, disease behavior, and drivers of inflammation in various patient subgroups which require further research.

Assessing the Effect of Vitamin D Replacement on Basal Cell Carcinoma Occurrence and Recurrence Rates in Patients with Vitamin D Deficiency

The study aimed to determine whether 25-OH vitamin D₃ deficiency is present in patients with diagnosed BCC, and the effect of vitamin D replacement on the rates of BCC recurrence in patients with 25-OH vitamin D₃ deficiency. In this prospective study, between 2012 and 2017, in the first stage, 25-OH vitamin D₃ levels of all patients diagnosed with BCC between 2012 and 2013 were evaluated. In the second stage between 2014 and 2015, we evaluated the 25-OH vitamin D₃ level of patients who had 25-OH vitamin D₃ level < 25 ng/mL. All the patients included in the second stage had BCC recurrence. In the third stage, the patients who were diagnosed 25-OH vitamin D₃ deficiency with BCC, between 2015 and 2017, were studied. The mean 25-OH vitamin D₃ level of the patients in the second stage was 10.12 ng/mL. Recurrence was observed in 9.64% of the patients in the second stage. The mean level of serum 25-OH vitamin D₃ in the third stage was 40.1 ng/mL, and 3.49% of these patients presented with recurrence. In all the patients as the initial diagnosis and following the 25-OH vitamin D₃ level in all the patients with BCC recurrence, maintaining 25-OH vitamin D₃ levels above 25 ng/mL can significantly reduce the recurrence rate.

Cellular and molecular mechanisms of vitamin D in food allergy

Food allergies are becoming increasingly prevalent, especially in young children. Epidemiological evidence from the past decade suggests a role of vitamin D in food allergy pathogenesis. Links have been made between variations in sunlight exposure, latitude, birth season and vitamin D status with food allergy risk. Despite the heightened interest in vitamin D in food allergies, it remains unclear by which exact mechanism(s) it acts. An understanding of the roles vitamin D plays within the immune system at the cellular and genetic levels, as well as the interplay between the microbiome and vitamin D, will provide insight into the importance of the vitamin in food allergies. Here, we discuss the effect of vitamin D on immune cell maturation, differentiation and function; microbiome; genetic and epigenetic regulation (eg DNA methylation); and how these processes are implicated in food allergies.

The Role of Vitamin D in Non-Scarring Alopecia

Non-scarring hair loss is a common problem that affects both male and female patients. Since any disturbances in the hair follicle cycle may lead to hair shedding, or alopecia, it is not surprising that the possible role of vitamin D in alopecia was investigated in many studies. Vitamin D has been shown to have many important functions. A growing body of evidence shows that vitamin D and its receptor are responsible for maintaining not only calcium homeostasis but also skin homeostasis. Moreover, vitamin D could also regulate cutaneous innate and adaptive immunity. This paper presents a review of current literature considering the role of vitamin D in alopecia areata, telogen effluvium, and female pattern hair loss. The majority of studies revealed decreased serum 25-hydroxyvitamin D levels in patients with different types of non-scarring alopecia, which could suggest its potential role in the pathogenesis of hair loss. According to the authors, vitamin D supplementation could be a therapeutic option for patients with alopecia areata, female pattern hair loss, or telogen effluvium. However, further studies on a larger group of patients are required.

Vitamin D intake during the first 4 years and onset of asthma by age 5: A nested case-control study

BACKGROUND

Early-life vitamin D intake has been linked to asthma risk in childhood, but the role of longitudinal vitamin D exposure has not been previously evaluated. We investigated the association between vitamin D intake during the first 4 years of life and asthma risk by age 5.

METHODS

Within a Finnish population-based birth cohort, 182 incident asthma cases were matched to 728 controls on sex, genetic risk for type 1 diabetes, delivery hospital, and time of birth. Vitamin D intake was assessed by age-specific 3 day food records. Parents completed a validated version of the International Study of Asthma and Allergies in Childhood questionnaire at 5 years.

RESULTS

At 3 months, supplements were the main source of vitamin D intake; intake from foods increased from 3 months on, mainly from fortified milk products. Vitamin D intake at each specific age was associated with an increased risk of any asthma, atopic, and non-atopic asthma, but only intake at 1 and 2 years was statistically significantly associated with asthma. Longitudinal vitamin D intake was associated with an increased risk of asthma (OR 1.24; 95%CI 1.00-1.53).

CONCLUSIONS

Increased vitamin D intake in childhood, particularly intake at 1 and 2 years of age, may increase risk of childhood asthma. This might reflect a true effect or residual confounding by lifestyle or environmental factors. Repeated assessment of vitamin D intake allowed evaluation of the longitudinal and age-dependent impact of vitamin D on the risk of asthma. Further longitudinal studies are required to confirm or question these findings.

Effect of 1,25(OH)2D3 on transdifferentiation of rat renal tubular epithelial cells induced by high glucose

Deficiency in vitamin D and its active metabolite is a characteristic of chronic kidney diseases (CKDs). Previous studies have reported that 1α,25-dihydroxyvitamin D₃ [1,25(OH)₂D₃], the active form of vitamin D, can attenuate renal interstitial fibrosis. The present study aimed to explore the effect of 1,25(OH)₂D₃ on the transdifferentiation of NRK-52E rat renal tubular epithelial cells (RTECs) induced by high glucose, as well as the expression of vitamin D receptor (VDR) and production of angiotensin (Ang) II. Western blot and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analyses were performed to detect the protein and mRNA expression of α-smooth muscle actin (α-SMA), E-cadherin and VDR. Furthermore, the production of Ang II was analyzed by enzyme-linked immunosorbent assay (ELISA). Treatment with high glucose decreased E-cadherin and VDR, while increasing α-SMA and Ang II, and of note, these changes were attenuated by 1,25(OH)₂D₃ in a dose-dependent manner. In conclusion, the present study revealed that 1,25(OH)₂D₃ inhibits high glucose-induced transdifferentiation of rat RTECs in a dose-dependent manner, which may be associated with the downregulation of Ang II and upregulation of VDR.

Association of T-regulatory cells and CD23/CD21 expression with vitamin D in children with asthma

BACKGROUND

Children with asthma have low vitamin D levels; however, we do not know whether low vitamin D is associated with impaired T-regulatory (Treg) cell population or high IgE receptors (CD23 and CD21) on B cells.

OBJECTIVE

To examine Treg cell function, CD23 and CD21 receptors, vitamin D, and vitamin D-regulating enzymes in children with asthma.

METHODS

Sixty children (2-6 years old) with asthma and 60 age-matched healthy children were selected as study participants. After collecting demographic and clinical data, blood samples were collected. Treg cells and CD23/CD21 expressions were evaluated by flow cytometry, 25-hydroxyvitamin D3 (25[OH]D3) was quantified by high-performance liquid chromatography, and cytokines and total IgE were estimated by enzyme-linked immunosorbent assay. Messenger RNA (mRNA) expressions of FOXP3, CD23, CD21, vitamin D receptors, and vitamin D-regulating enzymes were assessed by reverse transcription-polymerase chain reaction.

RESULTS

The 25(OH)D3 concentrations and proportion of Treg cells were lower (P < .05) among children with asthma. In contrast, the proportions of B cells with CD23 and CD21 expression were higher (P < .05) in patients with asthma compared with controls. Interleukin 10 and transforming growth factor β were also altered in asthma. The mRNA expression of CD23, CD21, and vitamin D receptors was up-regulated, whereas mRNA expression of vitamin D-regulating enzymes, CYP2R1, CYP27B1, and vitamin D binding protein (except CYP24A1) were up-regulated among children with asthma.

CONCLUSION

The current study found impaired Treg cell population and high numbers of B cells with IgE receptors (CD23 and CD21) and altered regulatory cytokines in children with asthma, suggesting impaired immune regulation.

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.

1,25-Dihydroxyvitamin D3 Facilitates M2 Polarization and Upregulates TLR10 Expression on Human Microglial Cells

OBJECTIVE

To explore the effects of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], the active metabolite of vitamin D, on M1/M2 polarization of human microglia and the expression of Toll-like receptor 10 (TLR10) on these cells, which has been suggested to play an inhibitory role in inflammation previously.

METHODS

Microglial HMO6 cells were treated with 1,25(OH)2D3, and mRNA or protein levels of M1 and M2 cytokines and TLR10 were examined.

RESULTS

1,25(OH)2D3 upregulated TLR10 in HMO6 cells at both mRNA and protein level. 1,25(OH)2D3 enhanced basal mRNA expression of M2 cytokines, such as IL-10 and CCL17, but did not affect the expression of M1 cytokines, including IL-12 and TNF-α. 1,25(OH)2D3 downregulated the lipopolysaccharide (LPS)-induced mRNA expression of M1 cytokines IL-12 and TNF-α. Concomitantly, it upregulated not only the M2 cytokines IL-10 and CCL17, but also TLR10 in microglial cells treated with LPS, in a concentration-dependent manner.

CONCLUSIONS

Our results suggest that 1,25(OH)2D3 may exert anti-inflammatory action by facilitating the M2 polarization of human microglial cells.

The Effects of Vitamin D Supplementation on Pulmonary Function of Chronic Obstructive Pulmonary Disease Patients, before and after Clinical Trial

Vitamin D has several extra calcemic effects. Vitamin D deficiency is highly prevalent in chronic obstructive pulmonary disease (COPD) patients but little is known about it’s association with lung function. Objective: To investigate whether supplementation with vitamin D could improve pulmonary function in COPD patients. Design: Before and after, double center, clinical trial. Setting: Hazrat Rasoul University Hospital, Tehran, and Imam Khomaini University Hospital, Ahvaz, Iran. Participants: 24 patients with mild to very severe COPD. Intervention: Loading dose of 300,000–600,000 International Units (IU) of vitamin D, then 50000 IU weekly for 12 weeks. Measurements: The outcomes included forced expiratory volume in one second (FEV1), forced vital capacity (FVC), vital capacity (VC), forced expiratory flow between 25%–75% of forced vital capacity (FEF 25%–75%), exercise capacity according to the six minute walk test(6MWT) and the saturation of oxygen during exercise. Results: The mean FEV1 (p-value = 0.866), FVC (p-value = 0.475) and VC (p-value = 0.425) were not significantly different before and after intervention. FEF 25%–75% did not improve with this intervention (p-value = 0.555). The vitamin D supplementation did not have any significant effect on the exercise capacity (p-value=0.175) or the saturation of oxygen (p-value = 0.635). Conclusion: Pulmonary function and exercise capacity did not improve with vitamin D supplementation in COPD patients.

Dietary diallyl disulfide supplementation attenuates ethanol-mediated pulmonary vitamin D speciate depletion in C57Bl/6 mice

Background

Slightly more than 5 % of the United States population heavily consumes ethanol, i.e., more than 14 drinks for men and 7 drinks for women a week. Chronic ethanol consumption can result in increased liver disease, reduced recovery from burn injury, and more frequent and severe respiratory infections. Chronic ethanol over-consumption also leads to vitamin D dysmetabolism and depletion. Vitamin D is a fat-soluble pro-hormone that regulates musculoskeletal health, cellular proliferation/differentiation, and innate and adaptive immune response.

Methods

In this study, C57BL/6 mice were fed 20 % ethanol in their water ad libitum for 7 weeks. Some mice were fed either a standard chow or a modified diet containing 0.15 μg/day of diallyl disulfide (DADS). Whole blood, lung tissue, and bronchial alveolar lavage fluid (BALF) were collected at sacrifice and analyzed for 25(OH) D₃, 1,25 (OH)₂D₃, vitamin D receptor VDR, CYP2E1, and CYP27B1 levels.

Results

Ethanol reduced 25(OH) D₃ and 1,25 (OH)₂D₃ in lung tissue and BALF on average 31 %. The largest ethanol-mediated reduction was in the 1,25 (OH)₂D₃ (42 %) measured in the BALF. Dietary supplementation of DADS restored BALF and lung tissue protein of 25(OH) D₃ and 1,25(OH)₂D₃ to control levels. Chronic ethanol consumption also resulted in tissue increases of vitamin D response (VDR) protein, Cyp2E1, and reductions in vitamin D-activating enzyme CYP27B1. All three of these effects were attenuated by dietary supplementation of DADS.

Conclusions

In conclusion, the pulmonary metabolic disturbances mediated by chronic ethanol consumption as measured by 1,25(OH)₂D₃ protein levels, epithelial lining fluid, and lung tissue can be ameliorated by dietary supplementation of DADS in C57BL/6 mice.

Vitamin D and inflammatory bowel disease

Vitamin D deficiency has been recognized as an environmental risk factor for Crohn's disease since the early 80s. Initially, this finding was correlated with metabolic bone disease. Low serum 25-hydroxyvitamin D levels have been repeatedly reported in inflammatory bowel diseases together with a relationship between vitamin D status and disease activity. Subsequently, low serum vitamin D levels have been reported in various immune-related diseases pointing to an immunoregulatory role. Indeed, vitamin D and its receptor (VDR) are known to interact with different players of the immune homeostasis by controlling cell proliferation, antigen receptor signalling, and intestinal barrier function. Moreover, 1,25-dihydroxyvitamin D is implicated in NOD2-mediated expression of defensin-β2, the latter known to play a crucial role in the pathogenesis of Crohn's disease (IBD1 gene), and several genetic variants of the vitamin D receptor have been identified as Crohn's disease candidate susceptibility genes. From animal models we have learned that deletion of the VDR gene was associated with a more severe disease. There is a growing body of evidence concerning the therapeutic role of vitamin D/synthetic vitamin D receptor agonists in clinical and experimental models of inflammatory bowel disease far beyond the role of calcium homeostasis and bone metabolism.

Anti-inflammatory effect of 1,25-dihydroxyvitamin D3 is associated with crosstalk between signal transducer and activator of transcription 5 and the vitamin D receptor in human monocytes

1,25-Dihydroxyvitamin D₃ (1,25-(OH)₂D₃) has an anti-inflammatory effect on human monocytes incubated with sera from patients with type 2 diabetes/diabetic nephropathy; however, the detailed mechanism behind the effect remains to be explored. The current study further validated the effects of 1,25-(OH)₂D₃ and lipopolysaccharide (LPS) + human recombinant interleukin (IL)-15 on the expression of the vitamin D receptor (VDR) and phosphorylated signal transducer and activator of transcription 5 (p-STAT5) in human monocytes and explored the possible interaction between VDR and p-STAT5. Synchronized THP-1 cells were divided into pre-intervened groups, namely the control, LPS + IL-15 and 1,25-(OH)₂D₃, groups, according to their differing treatments. The expression of STAT5 and p-STAT5 was evaluated by western blot analysis; the concentration of IL-6 in the supernatant was determined using an enzyme-linked immunosorbent assay; the expression of cytoskeletal proteins was observed using immunofluorescence and laser confocal microscopy; and the possible intranuclear interaction between VDR and p-STAT5 was investigated using immunofluorescence, immuno-coprecipitation and western blot analysis. LPS + IL-15 upregulated p-STAT5 expression and the IL-6 level (P<0.05), with cytoskeletal rearrangement. These effects were partially prevented through pretreatment with 1,25-(OH)₂D₃. The LPS + IL-15 group and the 1,25-(OH)₂D₃ group exhibited an interaction between p-STAT5 and VDR in the nucleus, with the latter group showing a significant increase compared with the former (P<0.05). The immuno-coprecipitation results provided evidence of the interaction between VDR and p-STAT5, which suggests the existence of STAT5-VDR crosstalk in THP-1 monocytes. Cytoskeletal rearrangement, VDR and p-STAT5 potentially have interactions in THP-1 monocytes. The anti-inflammatory effect of 1,25-(OH)₂D₃ may be associated with crosstalk between STAT5 and VDR, which further induces cytoskeletal rearrangement.

Vitamin D and skin cancer

Vitamin D signaling plays a key role in many important processes, including cellular proliferation, differentiation and apoptosis, immune regulation, hormone secretion and skeletal health. Furthermore, vitamin D production and supplementation have been shown to exert protective effects via an unknown signaling mechanism involving the vitamin D receptor (VDR) in several diseases and cancer types, including skin cancer. With over 3.5 million new diagnoses in 2 million patients annually, skin cancer is the most common cancer type in the United States. While ultraviolet B (UVB) radiation is the main etiologic factor for nonmelanoma skin cancer (NMSC), UVB also induces cutaneous vitamin D production. This paradox has been the subject of contradictory findings in the literature in regards to amount of sun exposure necessary for appropriate vitamin D production, as well as any beneficial or detrimental effects of vitamin D supplementation for disease prevention. Further clinical and epidemiological studies are necessary to elucidate the role of vitamin D in skin carcinogenesis.

Impaired T cell activation and cytokine production by calcitriol-primed human B cells

The biologically active form of vitamin D3 , 1, 25-dihydroxyvitamin D3 (calcitriol), is a potent modulator of the immune response. We have shown previously that calcitriol modulates the immunoglobulin response in vitro and in vivo in mice and humans. To analyse the underlying molecular mechanisms we studied whether calcitriol-primed B cells modulate T cell activation and function. Human B cells were stimulated with anti-CD40 and interleukin (IL)-4 in the presence of increasing concentrations of calcitriol. After removal of calcitriol, primed B cells were co-cultured with autologous CD4(+) T cells; the B cell phenotype T cell activation and their consecutive cytokine production were also assessed. Naive T cells co-cultured with calcitriol-primed naive B cells showed a reduced expansion, nuclear factor of activated T cells, cytoplasmic 2 (NFATc2) expression and cytokine production upon restimulation. CD86 expression on B cells after calcitriol priming was identified as an underlying mechanism, as T cell activation and expansion was rescued by activating anti-CD28 antibodies. Our data indicate that calcitriol-primed B cells display an impaired capacity to activate T cells. Taken together, we identified a novel B cell-dependent vitamin D immune regulatory mechanism, namely by decreased co-stimulation of calcitriol-primed B cells.

1,25-Dihydroxyvitamin D3 and its analog TX527 promote a stable regulatory T cell phenotype in T cells from type 1 diabetes patients

The emergence of regulatory T cells (Tregs) as central mediators of peripheral tolerance in the immune system has led to an important area of clinical investigation to target these cells for the treatment of autoimmune diseases such as type 1 diabetes. We have demonstrated earlier that in vitro treatment of T cells from healthy individuals with TX527, a low-calcemic analog of bioactive vitamin D, can promote a CD4⁺CD25^highCD127^low regulatory profile and imprint a migratory signature specific for homing to sites of inflammation. Towards clinical application of vitamin D-induced Tregs in autologous adoptive immunotherapy for type 1 diabetes, we show here that 1,25-dihydroxyvitamin D₃ [1,25(OH)₂D₃] and TX527 similarly imprint T cells from type 1 diabetes patients with a CD4⁺CD25^highCD127^low regulatory profile, modulate surface expression of skin- and inflammation-homing receptors, and increase expression of CTLA-4 and OX-40. Also, 1,25(OH)₂D₃ and TX527 treatment inhibit the production of effector cytokines IFN-γ, IL-9, and IL-17. Importantly, 1,25(OH)₂D₃ and TX527 promote the induction of IL-10-producing CD4⁺CD25^highCD127^low T cells with a stable phenotype and the functional capacity to suppress proliferation of autologous responder T cells in vitro. These findings warrant additional validation of vitamin D-induced Tregs in view of future autologous adoptive immunotherapy in type 1 diabetes.

Vitamin D status and PUFA ratios in a national representative cross-section of healthy, middle-aged Norwegian women – The Norwegian Women and Cancer Post-Genome Cohort

Aims: Vitamin D and polyunsaturated fatty acids (PUFAs) are derived from partially overlapping sources. Vitamin D is produced in the skin after sun exposure, but is also derived from fatty fish and fish oils. Dietary PUFAs are mainly derived from plant oils that are rich in n-6 PUFAs, but fatty fish provides high amounts of the marine n-3 PUFAs. The Western diet provides an excess of n-6 PUFAs compared to n-3 PUFAs, and the ratios of these may influence human health. Here, we investigated the potential associations of plasma concentrations of vitamin D, marine PUFAs and PUFA ratios. Methods: Plasma concentrations of vitamin D (25(OH)D), marine PUFAs, and PUFA ratios were measured in 372 women from the Norwegian Women and Cancer (NOWAC) Post-Genome Cohort. Covariability was examined in 310 non-users of cod liver oil, using Spearman’s rank correlation and linear regression. Results: In non-users of cod liver oil, the average concentration of vitamin D was 40.3 nmol/L, and marine PUFA concentration was 0.2 mg/g. PUFA ratios were dominated by the n-6 fatty acids. Vitamin D levels were significantly associated with marine fatty acids and weakly associated with PUFA ratios. Conclusions: Concentrations of vitamin D and marine PUFAs were below recommended levels. The correlation analyses indicated that health-related effects of vitamin D and marine PUFAs respectively may be hard to separate in epidemiological studies. However, measured health effects of PUFA ratios and vitamin D are likely to derive from the influence of the two factors separately. The presented results are the first to show these associations in a nationally representative cohort.

In older men, lower plasma 25-hydroxyvitamin D is associated with reduced incidence of prostate, but not colorectal or lung cancer

CONTEXT AND OBJECTIVE

Prostate, colorectal and lung cancers are common in men. In this study, we aimed to determine whether vitamin D status is associated with the incidence of these cancers in older men.

DESIGN

Prospective cohort study.

SETTING AND PARTICIPANTS

4208 older men aged 70-88 years in Perth, Western Australia.

MAIN OUTCOME MEASURES

Plasma 25-hydroxyvitamin D [25(OH)D] concentration was measured by immunoassay. New diagnoses of prostate, colorectal and lung cancers were determined via electronic record linkage.

RESULTS

During a mean follow-up of 6.7±1.8 years, there were 315, 117 and 101 new diagnoses of prostate, colorectal and lung cancer. In multivariate competing risks proportional hazards models, every 10 nmol/l decrease in 25(OH)D concentration was associated with a 4% reduction in prostate cancer incidence (sub-hazard ratio [SHR] 0.96, 95% confidence interval [CI] 0.92-1.00). Every halving of 25(OH)D concentration was associated with a 21% reduction in incident prostate cancer in multivariate analysis (SHR 0.79, 95% CI 0.63-0.99). Following exclusion of prostate cancer cases diagnosed within 3 years of blood sampling, low 25(OH)D <50 nmol/l was associated with lower incident prostate cancer, and higher 25(OH)D >75 nmol/l was associated with higher incidence, when compared to the reference range 50-75 nmol/l, respectively (p = 0.027). Significant associations were also observed when 25(OH)D was modeled as a quantitative variable. No associations were observed between plasma 25(OH)D concentration with incidence of colorectal or lung cancer.

CONCLUSION

Lower levels of vitamin D may reduce prostate cancer risk in older men. By contrast, levels of vitamin D did not predict incidence of colorectal or lung cancers. Further studies are needed to determine whether a causal relationship exists between vitamin D and prostate cancer in ageing men.

Biochemical efficacy of vitamin D in ameliorating endocrine and metabolic disorders in diabetic rats

CONTEXT

Due to the biochemical role of vitamin D (Vit D) in the endocrine system, especially its potential anti-inflammatory and immune-modulating properties, there is an increased interest in its potential role in the prevention and control of diabetes mellitus.

OBJECTIVE

This study evaluated the potential therapeutic efficacy of Vit D in averting the detrimental effects of both types of diabetes mellitus.

MATERIALS AND METHODS

A total of 50 male Wistar rats were allotted into five groups: a placebo group; a nongenetic model of type 1 diabetes in rats (T1D), injected with a single dose of streptozotocin (STZ; 65 mg/kg, ip); a nongenetic model of type 2 diabetes in rats (T2D), given a short-term high-fat diet followed by a single low dose of STZ (35 mg/kg, ip); fourth and fifth groups that were gastrogavaged with Vit D (10 IU/kg) three days after the induction of T1D and T2D, respectively, which was continued daily throughout the experiment.

RESULTS

Vit D (10 IU/kg/60 days) significantly (p < 0.05) decreased fasting plasma glucose, ketoacidosis (decreased non-esterified fatty acid and β-hydroxyl butyric acid), pro-inflammatory interleukin-6, HbA1c in T1D and T2D and insulin resistance index by 33% in T2D. Interestingly, Vit D significantly (p < 0.05) increased fasting plasma insulin by 144% in T1D, plasma Ca level, insulin sensitivity index, and β-cell function index in T1D and T2D.

DISCUSSION AND CONCLUSION

Vit D ameliorated the deleterious biochemical impact of diabetes mellitus, likely by increasing insulin secretion and sensitivity, ameliorating the β-cell function, and decreasing the number of pro-inflammatory cytokines and insulin resistance.

Immune, metabolic and epidemiological aspects of vitamin D in chronic kidney disease and transplant patients

Chronic kidney disease strongly impacts on mineral and bone metabolism. Despite numerous medications, the biological targets recommended by international guidelines are often unmet. Among the treatment armamentarium, native or nutritional vitamin D (25OHD3) has been rediscovered in the early 2000s, and its general and specific actions further studied. Effects on bone, immunity, infection prevention, muscle function and phosphocalcic metabolism have been reviewed. Assessment of nutritional vitamin D status showed very low serum 25OHD3 levels and increase in nutritional vitamin D prescription led to improvement in these levels. However, about 45% of adult CKD patients still have insufficient serum 25OHD3 levels. Epidemiological studies should be enforced to describe further the mineral and bone disease management in CKD.

Beyond mineral metabolism, is there an interplay between FGF23 and vitamin D in innate immunity?

Fibroblast growth factor 23 (FGF23) is an "endocrine" FGF acting in the kidney as a phosphaturic hormone and a suppressor of active vitamin D, through an inhibition of the 1α hydroxylase and a stimulation of the 24 hydroxylase. Beyond its well-known effects on the bone/kidney/parathyroid axis and its deregulation during chronic kidney disease (CKD), recent evidence has revealed its direct systemic effects on cardiovascular health. In the meantime, studies have highlighted the health implications for vitamin D inside and outside CKD that also extend beyond its classical actions on mineral homeostasis and bone metabolism: vitamin D has indeed been shown to exert pluripotent non-classical effects as a modulator of immune function in monocytes, mainly through the stimulation of the antimicrobial cathelicidin. The aim of this review is to provide new insights on the interplay between FGF23 and vitamin D in innate immunity in the context of CKD.

Plasma 25 hydroxyvitamin D level and blood gene expression profiles: a cross-sectional study of the Norwegian Women and Cancer Post-genome Cohort

BACKGROUND/OBJECTIVES

Vitamin D deficiency has been associated with increased risk of developing several diseases, but much is unknown about the molecular effects involved. Gene expression technology is increasingly being used to elucidate molecular mechanisms related to nutritional factors, and in this study of free-living, middle-aged Norwegian women, we aimed at identifying gene expression pathways in the blood associated with vitamin D status.

SUBJECTS/METHODS

Blood samples and questionnaires were collected as a part of the Norwegian Women and Cancer Post-genome Cohort (500 invited subjects, 218 included). Plasma 25 hydroxyvitamin D (25(OH)D) concentrations were measured using high-performance liquid chromatography, and we compared groups with sufficient versus deficient vitamin D status (25(OH)D >50 nmol/l (n=66) versus <37.5 nmol/l (n=83)), to identify differences in gene expression profiles obtained using full-genome microarrays.

RESULTS

In a targeted pathway-level analysis, several immunological processes, immune cell functions and major signaling pathways were differentially regulated according to vitamin D status (P<0.01). To a certain degree, results from in vitro studies reported in the literature were reflected in this population setting.

CONCLUSIONS

We conclude that vitamin D status measured as 25(OH)D was associated with molecular pathways that may ultimately affect the potential onset of diseases. The use of gene expression analysis in a population setting may give valuable input to the study of effects of nutritional factors.

Vitamin D: metabolism, molecular mechanisms, and mutations to malignancies

The potential protective effects of vitamin D against cutaneous carcinogenesis are still poorly understood. The inhibition, by vitamin D, of various cancers in in vitro and in vivo models has triggered detailed investigation of vitamin D effects on neoplastic behavior. Recent studies highlight that such neoplastic features as the tumor microenvironment, angiogenesis, DNA mutagenesis, and apoptosis are all connected to vitamin D metabolic pathways. This review discusses these connections. Vitamin D modulation of the cell cycle, DNA repair and apoptosis via its receptors (VDRs) may have a suppressive effect on skin cancer as some studies suggest. The regulation of multiple tumor signaling pathways by vitamin D may have an implication in cutaneous carcinogenesis and tumor progression to malignancy.

Vitamin D and asthma in children

Vitamin D deficiency and insufficiency are increasingly being recognized in the general population, and have been largely attributed to lifestyle changes (reduced exposure to sunshine due to working indoors or the use of protective clothing and sunscreen; changes in diet) over the last few decades. The musculoskeletal consequences of severe vitamin D deficiency are well established, however, a number of other disorders have now been linked to vitamin D insufficiency, including asthma. There is growing appreciation of the likely importance of vitamin D as a pleiotrophic mediator that contributes to pulmonary health. Children with asthma appear to be at increased risk of vitamin D insufficiency. Epidemiologic data suggest that low serum vitamin D in children with asthma is associated with more symptoms, exacerbations, reduced lung function, increased medication usage and severe disease. In vitro studies have demonstrated that vitamin D enhances steroid responsiveness in adult asthmatics. Vitamin D may play an important role in pulmonary health by inhibiting inflammation, in part through maintaining regulatory T cells, and direct induction of innate antimicrobial mechanisms. More research is required to fully understand the role of vitamin D in the maintenance of airway homeostasis and address the diagnostic and therapeutic implications vitamin D may have in the future of asthma management. This review summarises the current understanding and uncertainties regarding the effect of vitamin D deficiency and insufficiency in children with asthma.

Importance of apical membrane delivery of 1,25-dihydroxyvitamin D3 to vitamin D-responsive gene expression in the colon

Synthetic conjugation of a glucuronide to 1,25-dihydroxyvitamin D3 (1,25D3) to produce β-25-monoglucuronide-1,25D3 (βGluc-1,25D3) renders the hormone biologically inactive and resistant to mammalian digestive enzymes. However, β-glucuronidase produced by bacteria in the lower intestinal tract can cleave off the glucuronide, releasing the active hormone. In mice given a single oral dose of 1,25D3, 24-hydroxylase (Cyp24a1) gene expression was strongly enhanced in the duodenum, but not in the colon, despite circulating concentrations of 1,25D3 that peaked at ∼3.0 nmol/l. In contrast, in mice treated with an equimolar dose of βGluc-1,25D3, Cyp24a1 gene expression increased 700-fold in the colon but was significantly weaker in the duodenum compared with mice treated with 1,25D3. Similar results were observed with another vitamin D-dependent gene. When administered subcutaneously, 1,25D3 weakly stimulated colon Cyp24a1 gene expression while βGluc-1,25D3 again resulted in strong enhancement. Surgical ligation to block passage of ingesta beyond the upper intestinal tract abolished upregulation of colon Cyp24a1 gene expression by orally and subcutaneously administered βGluc-1,25D3. Feeding βGluc-1,25D3 for 5 days revealed a linear, dose-dependent increase in colon Cyp24a1 gene expression but did not significantly increase plasma 1,25D3 or calcium concentrations. This study indicates that the colon is relatively insensitive to circulating concentrations of 1,25D3 and that the strongest gene enhancement occurs when the hormone reaches the colon via the lumen of the intestinal tract. These findings have broad implications for the use of vitamin D compounds in colon disorders and set the stage for future therapeutic studies utilizing βGluc-1,25D3 in their treatment.

Effect of vitamin D supplementation on Mycobacterium tuberculosis-induced innate immune responses in a Canadian Dené First Nations cohort

Canadian First Nations (FN) population experiences a high burden of tuberculosis. Vitamin D is known to enhance the expression of innate immune effectors, including cathelicidin LL-37, for protection against infections. In this study we performed longitudinal analyses to investigate the impact of vitamin D supplementation on macrophage responses to Mycobacterium tuberculosis (Mtb) lipoprotein (TLR2/1L), in Canadian Dené FN participants compared to Caucasian participants. Serum 25(OH)D and LL-37 levels were evaluated by ELISA. Transcriptional responses and protein expression of TLR2/1L-induced LL-37 and other innate immune cytokines were monitored in monocyte-derived macrophages (MDMs) before and after 8 months of vitamin D supplementation. In this study we showed that serum levels of LL-37 decreased after vitamin D supplementation in both Dené and Caucasian participants. There was no difference in TLR2/1L-induced LL-37 expression in MDMs in the two groups, either pre- or post-vitamin D supplementation. However, vitamin D supplementation markedly enhanced TLR2/1L-induced responses in MDMs e.g. IL-6, IL-12 and IL-23 among Caucasians but not in the Dené participants. In contrast, after vitamin D supplementation TLR2/1L-induced responses e.g. IL-1β, IL-8 and IL-12 were significantly reduced in the Dené MDMs. These results indicate that vitamin D supplementation enhanced TLR2/1L-induced innate immune macrophage responses in the Caucasian but not in the Dené participants. We hypothesize that cytokines may be differentially regulated in Canadian FN compared to Caucasians, in particular those that influence Th-1 and Th-17 responses required for the control of Mtb.

The immunoregulatory function of vitamin D: implications in chronic kidney disease

Cardiovascular and infectious diseases remain the most common causes of death among patients with chronic kidney disease (CKD) and end-stage renal disease (ESRD). Basic science and epidemiological studies indicate that vitamin D has importance not only for cardiovascular health, but also for the immune response. Vitamin D signaling pathways regulate both innate and adaptive immunity, maintaining the associated inflammatory response within physiological limits. Levels of both the inactive as well as active form of vitamin D (25-hydroxyvitamin D and 1,25-dihydroxyvitamin D, respectively) are decreased in patients with CKD and ESRD. It is reasonable to hypothesize, therefore, that the immune dysfunction associated with vitamin D deficiency in patients with CKD and ESRD in part explains the misdirected inflammatory response and increased susceptibility to infection seen in this population. Indeed, observational studies show that vitamin D deficiency in patients with ESRD is associated with increased mortality, and treatment with vitamin D is associated with a decreased risk of infection, as well as reduced all-cause mortality. However, whether different vitamin D preparations have differential effects on physiological function and clinical outcomes is still unclear. A proper understanding of the immune regulatory function of vitamin D is important for the development of future therapeutic strategies.

Role of vitamin D metabolism in cutaneous tumour formation and progression

OBJECTIVES

Very limited information is available on the role of vitamin D in skin carcinogenesis. For most individuals, skin cancer can be readily managed with surgery; however, some patients may face life-threatening neoplasia. Sun exposure, specifically UV radiation, is a causative agent for development of skin cancer, though, somewhat ironically, sunlight through the production of vitamin D may have protective effect against some skin cancers. This review focuses on the development and progression of cutaneous carcinogenesis and the role of vitamin D in the prevention of the initiation and progression of lethal skin cancers.

KEY FINDINGS

Vitamin D is involved in regulation of multiple signalling pathways that have implications in carcinogenesis. Skin cancer metastasis depends on the tumour microenvironment, where vitamin D metabolites play a key role in prevention of certain molecular events involved in tumour progression. The vitamin D receptor (VDR) is a well-known potent regulator of cellular growth and differentiation.

SUMMARY

The VDR's possible involvement in cell death, tumour microenvironment and angiogenesis makes it a candidate agent for cancer regulation.

Vitamin D and diabetes

There is no doubt that vitamin D deficiency is the cause of several metabolic bone diseases, but vitamin D status is also linked to many major human diseases including immune disorders. Mounting data strengthen the link between vitamin D and diabetes, in particular T1D and T2D. Despite some inconsistencies between studies that associate serum 25(OH)D levels with the risk of developing T1D or T2D, there seems to be an overall trend for an inverse correlation between levels of 25(OH)D and both disorders. There is also compelling evidence that 1,25(OH)2D regulates b-cell function by different mechanisms, such as influencing insulin secretion by regulating intracellular levels of Ca2+, increasing β-cell resistance to apoptosis, and perhaps also increasing β-cell replication. The capacity of vitamin D, more specifically 1,25(OH)2D, to modulate immune responses is of particular interest for both the therapy and prevention of diabetes. In the case of T1D, vitamin D supplementation in prediabetic individuals could help prevent or reduce the initiation of autoimmune processes possibly by regulating thymic selection of the T-cell repertoire, decreasing the numbers of autoreactive T cells, and inducing Treg cells. Although immune modulation is generally discussed for the treatment of T1D, it is also relevant for T2D. Indeed, recent studies have shown that T2D patients have increased systemic inflammation and that this state can induce β-cell dysfunction and death. Supplementation trials with regular vitamin D for the protection against the development of T1D and T2D have generated some contradictory data, but many weaknesses can be identified in these trials as most were underpowered or open-labeled. However, the overwhelming strength of preclinical data and of the observational studies make vitamin D or its analogues strong candidates for the prevention or treatment of diabetes or its complications. However, proof of causality needs well-designed clinical trials and if positive, adequate dosing, regimen, and compound studies are needed to define the contribution of vitamin D status and therapy in the global diabetes problem. There are many confounding factors that need to be taken into consideration when translating successful vitamin D therapies in animal models into humans, for example, gender, age, lifestyle, and genetic background. To come to solid conclusions on the potential of vitamin D or its analogues in the prevention of or therapy for all forms of diabetes, it is clear that large prospective trials with carefully selected populations and end points will be needed, but should also receive high priority.

Worsening severity of vitamin D deficiency is associated with increased length of stay, surgical intensive care unit cost, and mortality rate in surgical intensive care unit patients

BACKGROUND

Vitamin D deficiency is the most common nutritional deficiency in the United States. It is seldom measured or recognized, and rarely is treated, particularly in critically ill patients. The purpose of this study was to investigate the prevalence and impact of vitamin D deficiency in surgical intensive care unit patients. We hypothesized that severe vitamin D deficiency increases the length of stay, mortality rate, and cost in critically ill patients admitted to surgical intensive care units.

METHODS

We performed a prospective observational study of vitamin D status on 258 consecutive patients admitted to the Surgical Intensive Care Unit at Grady Memorial Hospital between August 2009 and January 2010. Vitamin D levels (25 [OH]2 vitamin-D3) were measured by high-pressure liquid chromatography and tandem mass spectrometry. Vitamin D deficiency was defined as follows: severe deficiency was categorized as less than 13 ng/mL; moderate deficiency was categorized as 14 to 26 ng/mL; mild deficiency was categorized as 27 to 39 ng/mL; and normal levels were categorized as greater than 40 ng/mL.

RESULTS

Of the 258 patients evaluated, 70.2% (181) were men, and 29.8% (77) were women; 57.6% (148) were African American and 32.4% (109) were Caucasian. A total of 138 (53.5%) patients had severe vitamin D deficiency, 96 (37.2%) had moderate deficiency, 18 (7.0%) had mild deficiency, and 3 (1.2%) of the patients had normal vitamin D levels. The mean length of stay in the Surgical Intensive Care Unit for the severe vitamin D-deficient group was 13.33 ± 19.5 days versus 7.29 ± 15.3 days and 5.17 ± 6.5 days for the moderate and mild vitamin D-deficient groups, respectively, which was clinically significant (P = .002). The mean treatment cost during the patient stay in the surgical intensive care unit was $51,413.33 ± $75,123.00 for the severe vitamin D-deficient group, $28,123.65 ± $59,752.00 for the moderate group, and $20,414.11 ± $25,714.30 for the mild vitamin D-deficient group, which also was clinically significant (P = .027). More importantly, the mortality rate for the severe vitamin D-deficient group was 17 (12.3%) versus 11 (11.5%) in the moderate group (P = .125). Because no deaths occurred in the mildly or normal vitamin D-deficient groups, we compared the mortality rate between severe/moderate and mild/normal vitamin D groups (P = .047).

CONCLUSIONS

In univariate analysis, severe and moderate vitamin D deficiency was related inversely to the length of stay in the surgical intensive care unit (r = .194; P = .001), related inversely to surgical intensive care unit treatment cost (r = .194; P = .001) and mortality (r = .125; P = .023), compared with the mild vitamin D-deficient group, after adjusting for age, sex, race, and comorbidities (myocardial infarctions, acute renal failure, and pneumonia); the length of stay, surgical intensive care unit cost, and mortality remained significantly associated with vitamin D deficiency.

Translating the role of vitamin D3 in infectious diseases

Vitamin D(3) affects both the innate as well as adaptive immune responses. Epidemiological studies have established that vitamin D(3) deficiency plays an important role in tuberculosis (TB) and viral influenza prevalence as well as susceptibility to active disease in TB. Vitamin D(3) status has been associated with the clinical course of HIV infection and drug interaction with anti-retroviral therapy. This article reviews the immunomodulatory capacity of vitamin D(3) and examines the impact of vitamin D(3) supplementation as a preventive or therapeutic intervention with the intent to uncover its potential therapeutic application in infectious diseases and to identify novel areas for future research. We present a review of randomized, controlled clinical studies conducted in humans which included assessment of the immune function or clinical outcome as study end points. Current data support vitamin D(3) supplementation as risk-modifying intervention in tuberculosis and viral respiratory tract infection, but the optimal dosage regimen remains to be determined. However, to date the knowledge on its role in fungal infection and sepsis is limited although a potential benefit could be harnessed from its ability to curtail the unrestrained pro-inflammatory response and therefore prevent excessive collateral tissue damage.

Targeted delivery of vitamin D to the colon using β-glucuronides of vitamin D: therapeutic effects in a murine model of inflammatory bowel disease

1,25-Dihydroxyvitamin D(3) [1,25(OH)(2)D] has been shown to inhibit development of dextran sodium sulfate (DSS)-induced colitis in mice but can also cause hypercalcemia. The aim of this study was to evaluate whether β-glucuronides of vitamin D could deliver 1,25(OH)(2)D to the colon to ameliorate colitis while reducing the risk of hypercalcemia. Initial studies demonstrated that bacteria residing in the lower intestinal tract were capable of liberating 1,25(OH)(2)D from 1,25-dihydroxyvitamin D(3)-25-β-glucuronide [β-gluc-1,25(OH)(2)D]. We also determined that a much greater upregulation of the vitamin D-dependent 24-hydroxylase gene (Cyp24) was induced in the colon by treatment of mice with an oral dose of β-gluc-1,25(OH)(2)D than 1,25(OH)(2)D, demonstrating targeted delivery of 1,25(OH)(2)D to the colon. We then tested β-glucuronides of vitamin D in the mouse DSS colitis model in two studies. In mice receiving DSS dissolved in distilled water and treated with 1,25(OH)(2)D or β-gluc-1,25(OH)(2)D, severity of colitis was reduced. Combination of β-gluc-1,25(OH)(2)D with 25-hydroxyvitamin D(3)-25-β-glucuronide [β-gluc-25(OH)D] resulted in the greatest reduction of colitis lesions and symptoms in DSS-treated mice. Plasma calcium concentrations were lower in mice treated with β-gluc-1,25(OH)(2)D alone or in combination with β-gluc-25(OH)D than in mice treated with 1,25(OH)(2)D, which were hypercalcemic at the time of death. β-Glucuronides of vitamin D compounds can deliver 1,25(OH)(2)D to the lower intestine and can reduce symptoms and lesions of acute colitis in this model.

Vitamin D and Chronic Obstructive Pulmonary Disease

Vitamin D is an important regulator of calcium and bone homeostasis. It is also involved in the regulation of different genes and cellular functions, particularly in the context of inflammation, regeneration and immune control. Conversely, vitamin D deficiency which is often found in chronic, infectious and inflammatory diseases is thought to drive or enhance uncontrolled inflammation. Chronic obstructive pulmonary disease (COPD) is characterized by chronic inflammation of the airways most often because of cigarette smoking. It has been recognized that repetitive airway infections and systemic consequences or co-morbidities also contribute to the progressive nature of COPD. Vitamin D deficiency is known to sneak in from the early stages of COPD, to become highly prevalent at the more severe stages, and may thereby catalyse airway infection, inflammation and systemic consequences. Undoubtedly, vitamin D deficiency enhances bone resorption and osteoporosis in COPD for which appropriate vitamin D supplementation is recommended. However, conflicting evidence has emerged on the extra-calcemic effects of vitamin D in COPD. A recent intervention trial with high-dose supplementation in COPD was only able to reduce exacerbation frequency in the subgroup of patients with lowest baseline vitamin D levels. It confirms that severe vitamin D deficiency is a health hazard but that more clinical and experimental studies are needed to explore how vitamin D deficiency may affect airway biology and systemic effects in the context of smoke-induced lung diseases.

1,25-Dihydroxyvitamin D3 alters murine dendritic cell behaviour in vitro and in vivo

BACKGROUND

Differentiation and maturation of dendritic cells yield a cell type with the ability to prime immune responses towards defence and destruction. 1,25(OH)2D3, the active form of vitamin D3, fosters the development of tolerogenic dendritic cells. This study aimed to evaluate the effects of 1,25(OH)2D3 on murine dendritic cell behaviour in vitro and in vivo.

METHODS

Dendritic cells were differentiated from bone marrow cells of female C57Bl/6 mice in the presence or absence of 10(-8) M 1,25(OH)2D3 for 8 days (IL4 and GM-CSF). Maturation was induced for 48 h (IFNγ, LPS and BALB/C islet homogenate antigen).

RESULTS

Bone marrow-derived dendritic cells displayed a different surface marker profile in the presence of 1,25(OH)2D3 with decreased MHC II, CD86 and CD80 and increased CCR5, DEC205, F4/80 and CD40, as well as lower IL6 and IL12 expression upon LPS/IFNγ stimulation. T-cell proliferation was significantly reduced when exposed to islet antigen-loaded 1,25D3-DCs as compared to control dendritic cells and IL4, IL10, TNFα and TGFβ levels were increased. In vivo, transfer of islet antigen-loaded control dendritic cells resulted in priming of the immune system and hyperacute islet allograft rejection (4/4), whereas this was prevented in 5/7 mice treated with islet antigen-loaded 1,25D3-DCs.

CONCLUSION

We conclude that in vitro 1,25(OH)2D3 exposure alters dendritic cell behaviour, converting them into a cell type that drives T cells away from destruction towards a regulatory phenotype.

Maternal vitamin D during pregnancy and its relation to immune-mediated diseases in the offspring

Vitamin D deficiency during pregnancy is fairly common in many parts of the world. However, currently there is no consensus on the optimal vitamin D intake during pregnancy. Vitamin D is known to be of great importance for the homeostatic functions within the immune system. Maternal vitamin D status during pregnancy may therefore affect the developing immune system of the fetus, thus contributing to the later development of immune-mediated diseases. This chapter introduces the basics of vitamin D during pregnancy and discusses the role of maternal vitamin D intake in the development of asthma, allergic diseases, autoimmune diseases, cancer, and infections in the offspring. So far, the strongest observational evidence underlines the potential of maternal vitamin D intake during pregnancy to influence the likelihood of asthma and allergic outcomes in the offspring. Somewhat conflicting findings imply that there might be critical time windows of exposure to adequate vitamin D levels during pregnancy. More research is needed in order to fully understand the contribution of maternal vitamin D status during pregnancy to the progress of immune-mediated diseases.

Alteration of vitamin D metabolic enzyme expression and calcium transporter abundance in kidney involved in type 1 diabetes-induced bone loss

This study aimed to delineate the mechanism involved in type 1 diabetes-induced bone loss. The results revealed the alteration of vitamin D metabolic enzyme expression and the downregulation of renal calcium transporter abundance in type 1 diabetic mice.

INTRODUCTION

The purpose of this study was to investigate the changes of the expression of vitamin D metabolic enzymes and transcellular calcium-transporting proteins in kidneys from mice with experimentally induced diabetes.

METHODS

Male DBA/2J mice were injected with either vehicle (control) or streptozotocin (STZ) daily for five consecutive days. Bone mineral density was measured by peripheral quantitative computerized tomography, and bone histomorphology was analyzed by Safranin O staining. Real-time PCR and Western blotting were applied to determine the expression of target genes and proteins.

RESULTS

Type 1 diabetes produced high urinary calcium excretion and loss of trabecular bone measured at the proximal metaphysis of the tibia and the distal femur. Bone loss was associated with deterioration of trabecular bone microstructure. Quantified PCR results showed that mRNA expression level in the kidney of diabetic mice for 25-hydroxyvitamin D-24-hydroxylase was downregulated at week 10, while those for 25-hydroxyvitamin D-1α-hydroxylase were upregulated at week 20. In addition, mRNA expression levels for renal transient receptor potential V6, plasma membrane Ca-ATPase (PMCA)1b, and vitamin D receptor (VDR) genes were decreased in STZ-treated mice. Western blot analysis showed that protein expression of PMCA1b and VDR was significantly decreased in kidneys from STZ-treated mice compared to that of controls.

CONCLUSIONS

The limitation in this study is the lack of vitamin D, parathyroid hormone, and phosphorus levels in serum. However, the present study supports the conclusion that the underlying mechanism contributing to type 1 diabetes-associated bone loss may be alterations of vitamin D metabolic enzyme expression and associated decreases in expression of renal calcium transporters.

Tanning predicts bone mass but not structure in adolescent females living in Hawaii

OBJECTIVES

To evaluate the relationship between facultative skin pigmentation, which predicts circulating levels of plasma 25-hydroxymitamin D, and several measures of bone mass and structure in a cross sectional sample of adolescent females living in Hawaii.

METHODS

Our sample was composed of adolescent females (n = 94) living in Hawaii where seasonal sun exposure is minimal, and who self-identified as either white (n = 16) or Asian (n = 78). Bone mineral content (BMC) of the total body, the lumbar spine and the hip, and cross sectional area (CSA) and section modulus (Z) at the proximal femur were quantified using DXA. Facultative skin pigmentation was measured at the forehead and non-facultative skin pigmentation was measured at the inner arm using a Chroma Meter CR-200b colorimeter.

RESULTS

There were no significant differences between ethnic groups in terms of skin pigmentation. The difference between a* taken at the forehead and inner upper arm significantly predicted BMC at the lumbar spine, total hip, and total body. Other measures of skin pigmentation were not significant predictors of any other measure of skeletal integrity.

CONCLUSIONS

The difference between facultative and non-facultative skin pigmentation for a* is a significant predictor BMC, but not bone structure. Our findings are limited by an inability to control for long term UVA and UVB exposure and lack of a measure of serum 25(OH)D status. Further research is needed to examine these questions, particularly in populations who live at high latitudes where a winter season limits vitamin D(3) synthesis.

Vitamin D: drug of the future. A new therapeutic approach

Besides increasing calcium absorption in the bowel and promoting the normal formation and mineralization of bone, vitamin D exerts relevant pleiotropic effects in different tissues. Serum levels of vitamin D show correlation with the risk of infections, cardiovascular diseases, cancer and autoimmune disorders. The possible therapeutic role of vitamin D in different kind of diseases: inflammatory, immunologic, infectious and neoplastic ones, explains the growing interest in this vitamin due to its pleiotropic effects, and makes it a candidate to become a potential drug in the next future.