Vitamin D 3 and the immune system: maintaining the balance in health and disease

Vitamin D and reproductive disorders: a comprehensive review with a focus on endometriosis

Vitamin D is a fat-soluble steroid hormone that was initially known only for regulating calcium and phosphorus levels and maintaining bone health. However, it was later discovered that many organs express vitamin D metabolizing enzymes and have a ligand for vitamin D, which regulates the expression of an extensive assortment of genes. As a result, vitamin D is indispensable for the proper function of organs, and its deficiency is believed to be a critical factor in symptoms and disorders such as cardiovascular diseases, autoimmune diseases, and cancers. The significance of vitamin D in reproductive tissues was recognized later, and studies have revealed its crucial role in male and female fertility, as well as proper reproductive function during pregnancy. Vitamin D deficiency has been identified as a risk factor for infertility, gonadal cancers, pregnancy complications, polycystic ovary syndrome, and endometriosis. However, data investigating the association between vitamin D levels and reproductive disorders, including endometriosis, have encountered inconsistencies. Therefore, the present study aims to review existing research on the effect of vitamin D on proper reproductive function, and the role of deficiency in reproductive diseases and specifically focuses on endometriosis.

25-hydroxyvitamin D and Endometriosis: A bidirectional Mendelian randomization study

Numerous studies have demonstrated a correlation between serum 25-hydroxyvitamin D (25OHD) and endometriosis. However, the precise nature of this association remains elusive. The causal connection between 25OHD and endometriosis remains uncertain, as it is yet to be determined whether one directly influences the other. The objective of our research was to investigate the cause-and-effect connection between 25OHD and endometriosis. The study employed Mendelian randomization (MR) in a bidirectional two-sample investigation to examine the causal relationship between 25OHD and endometriosis. The analysis utilized the most recent publicly accessible statistics from the genome-wide association study (GWAS) encompassing 25OHD, endometriosis, and its five subtypes. The primary analytical approach employed was Inverse-Variance Weighting (IVW), accompanied by supplementary analysis methods including weighted median, MR-Egger, simple mode, and weighted mode. Furthermore, sensitivity analyses were conducted to assess the potential influence of heterogeneity and pleiotropy on the MR outcomes. MR primary analysis showed no significant causal effect of 25OHD on endometriosis (OR = 0.892, 95%CI = 0.745 ~ 1.068, P = 0.213). Similarly, there was no evidence to support a causal relationship of endometriosis on 25OHD (IVW Beta = 0.005, 95%CI = 0.993 ~ 1.018, P = 0.406). However, when conducting MR analysis on different subtypes of endometriosis and 25OHD, we found a positive correlation between endometriosis of ovary and 25OHD level (IVW Beta = 0.012, 95%CI = 1.002 ~ 1.022, P = 0.024). This study indicates that there is no causal relationship between serum 25OHD and endometriosis. However, it is important to note that serum 25OHD levels will increase in patients with endometriosis of the ovary. Further observational studies and clinical trials are indispensable.

Vitamin D in Diabetes: Uncovering the Sunshine Hormone's Role in Glucose Metabolism and Beyond

Over the last decades, epidemiology and functional studies have started to reveal a pivotal role of vitamin D in both type 1 and type 2 diabetes pathogenesis. Acting through the vitamin D receptor (VDR), vitamin D regulates insulin secretion in pancreatic islets and insulin sensitivity in multiple peripheral metabolic organs. In vitro studies and both T1D and T2D animal models showed that vitamin D can improve glucose homeostasis by enhancing insulin secretion, reducing inflammation, reducing autoimmunity, preserving beta cell mass, and sensitizing insulin action. Conversely, vitamin D deficiency has been shown relevant in increasing T1D and T2D incidence. While clinical trials testing the hypothesis that vitamin D improves glycemia in T2D have shown conflicting results, subgroup and meta-analyses support the idea that raising serum vitamin D levels may reduce the progression from prediabetes to T2D. In this review, we summarize current knowledge on the molecular mechanisms of vitamin D in insulin secretion, insulin sensitivity, and immunity, as well as the observational and interventional human studies investigating the use of vitamin D as a treatment for diabetes.

On the Centennial of Vitamin D-Vitamin D, Inflammation, and Autoimmune Thyroiditis: A Web of Links and Implications

The 100th anniversary of the discovery of vitamin D3 (VitD3) coincides with significant recent advances in understanding its mechanism of action along with accumulating knowledge concerning its genomic and nongenomic activities. A close relationship between VitD3 and the immune system, including both types of immunity, innate and adaptive, has been newly identified, while low levels of VitD3 have been implicated in the development of autoimmune thyroiditis (AIT). Active 1,25(OH)₂ D3 is generated in immune cells via 1-α-hydroxylase, subsequently interacting with the VitD3 receptor to promote transcriptional and epigenomic responses in the same or adjacent cells. Despite considerable progress in deciphering the role of VitD3 in autoimmunity, its exact pathogenetic involvement remains to be elucidated. Finally, in the era of coronavirus disease 2019 (COVID-19), brief mention is made of the possible links between VitD3 deficiency and risks for severe COVID-19 disease. This review aims to commemorate the centennial of the discovery of VitD3 by updating our understanding of this important nutrient and by drawing up a framework of guidance for VitD3 supplementation, while emphasizing the necessity for personalized treatment in patients with autoimmune thyroid disease. A tailored approach based on the specific mechanisms underlying VitD3 deficiency in different diseases is recommended.

Immunoceuticals: Harnessing Their Immunomodulatory Potential to Promote Health and Wellness

Knowledge that certain nutraceuticals can modulate the immune system is not new. These naturally occurring compounds are known as immunoceuticals, which is a novel term that refers to products and systems that naturally improve an individual’s immuno-competence. Examples of immunoceuticals include vitamin D3, mushroom glycans, flavonols, quercetin, omega-3 fatty acids, carotenoids, and micronutrients (e.g., zinc and selenium), to name a few. The immune system is a complex and highly intricate system comprising molecules, cells, tissues, and organs that are regulated by many different genetic and environmental factors. There are instances, such as pathological conditions, in which a normal immune response is suboptimal or inappropriate and thus augmentation or tuning of the immune response by immunoceuticals may be desired. With infectious diseases, cancers, autoimmune disorders, inflammatory conditions, and allergies on the rise in both humans and animals, the importance of the use of immunoceuticals to prevent, treat, or augment the treatment of these conditions is becoming more evident as a natural and often economical approach to support wellness. The global nutraceuticals market, which includes immunoceuticals, is a multi-billion-dollar industry, with a market size value of USD 454.55 billion in 2021, which is expected to reach USD 991.09 billion by 2030. This review will provide an overview of the immune system, the importance of immunomodulation, and defining and testing for immunocompetence, followed by a discussion of several key immunoceuticals with clinically proven and evidence-based immunomodulatory properties.

Diet and Systemic Lupus Erythematosus (SLE): From Supplementation to Intervention

BACKGROUND

Systemic lupus erythematosus (SLE) is a chronic autoimmune inflammatory disease characterised by immune dysregulation affecting multiple organs. Current anti-inflammatory treatments used in SLE are associated with unwanted side-effects. Dietary supplementation has been suggested as a safe and effective addition to conventional treatment, but evidence of efficacy in SLE or preventing associated comorbidities is uncertain.

METHODS

We identified literature on clinical trials focused on nutritional interventions in SLE aiming to improve inflammation and comorbidities. A systematic-type search on Embase, Medline, and the Cochrane Library, was conducted to identify nutritional interventions among SLE patients in the past 15 years that met our inclusion criteria.

RESULTS

We identified 2754 articles, of which 14 were eligible for inclusion based on our set criteria and were subsequently quality assessed. Vitamin D or E supplementation was associated with respective improvement of inflammatory markers or antibody production, but not disease activity scores in most studies. Despite their expected synergistic actions, the addition of curcumin on vitamin D supplementation had no additional effects on disease activity or inflammatory markers. Trials of omega-3 fatty acid supplementation presented significant reductions in ESR, CRP, disease activity, inflammatory markers, and oxidative stress, and improved lipid levels and endothelial function, while a low glycaemic index (GI) diet showed evidence of reduced weight and improved fatigue in patients.

CONCLUSIONS

Different dietary guidelines can therefore be implicated to target specific SLE symptoms or therapeutic side-effects. This systematic review highlights the scarcity of larger and longer in duration trials with homogenous methodologies and verifiable outcomes to assess disease progression.

Prognostic Value of Catestatin in Severe COVID-19: An ICU-Based Study

Catestatin is a pleiotropic peptide with a wide range of immunomodulatory effects. Considering that patients with a severe COVID-19 infection have a major immunological dysregulation, the aim of this study was to evaluate catestatin levels in patients with COVID-19 treated in the intensive care unit (ICU) and to compare them between the fatal and non-fatal outcomes. The study included 152 patients with severe COVID-19, out of which 105 had a non-fatal outcome and 47 had a fatal outcome. Serum catestatin levels were estimated by an enzyme-linked immunosorbent assay in a commercially available diagnostic kit. The results show that catestatin levels were significantly lower in the fatal group compared to the non-fatal group (16.6 ± 7.8 vs. 23.2 ± 9.2 ng/mL; p < 0.001). Furthermore, there was a significant positive correlation between serum catestatin levels and vitamin D levels (r = 0.338; p < 0.001) while there was also a significant positive correlation between serum catestatin levels and growth differentiation factor-15 (GDF-15) levels (r = −0.345; p < 0.001). Furthermore, multivariate logistic regression showed that catestatin, GDF-15 and leukocyte count were significant predictors for COVID-19 survival. These findings imply that catestatin could be playing a major immunomodulatory role in the complex pathophysiology of the COVID-19 infection and that serum catestatin could also be a predictor of a poor COVID-19 outcome.

Vitamin D and COVID-19: An Overview of Recent Evidence

The novel coronavirus severe acute respiratory syndrome (SARS-CoV-2) has progressed rapidly from an outbreak to a global pandemic, with new variants rapidly emerging. Coronavirus disease 2019 (COVID-19), the disease resulting from SARS-CoV-2 infection, can lead to multiorgan damage. Due to the extremely contagious and fatal nature of the virus, it has been a priority of medical research to find effective means of treatment. Amid this search, the role of vitamin D in modulating various aspects of the innate and adaptive immune system has been discussed. This review aims to consolidate the research surrounding the role of vitamin D in the treatment and prevention of COVID-19. While there are some conflicting results reported, the consensus is that vitamin D has a host of immunomodulatory effects which may be beneficial in the context of COVID-19 and that low levels of vitamin D can result in dysfunction of crucial antimicrobial effects, potentially contributing to poor prognosis. Studies also show that the effects of low vitamin D can be mitigated via supplementation, although the benefits of vitamin D supplementation in the treatment of COVID-19 remain controversial.

The combination of vitamin D3 and erythropoietin alleviates acute kidney injury induced by ischemia-reperfusion via inhibiting inflammation and apoptosis

OBJECTIVES

Acute renal ischemia may cause acute renal dysfunction due to lack of blood supply; the manifestations are renal tubular cell apoptosis, infiltration of macrophages, and microvascular destruction. Many studies have shown that erythropoietin (EPO) and vitamin D3 (VD3) can be used to prevent or treat renal ischemia-reperfusion (I/R) injury, and VD3 may interact with EPO. In the present study, the effects of the combination of VD3 and EPO in I/R acute kidney injury were studied.

MATERIALS AND METHODS

Rats were divided into 5 groups: sham-operated (SHAM), AKI without treatment (AKI-control), AKI treatment with VD3(AKI+VD3), AKI treatment with EPO(AKI+EPO), AKI treatment with VD3 and EPO(AKI+VD3+EPO). The effects of the combination of VD3 and EPO on AKI were assessed by histologic, inflammation, and apoptosis studies.

RESULTS

The degree of damage in renal tissue was significantly reduced in VD3, EPO, and combined groups. Combination therapy with VD3 and EPO markedly improved Creatinine clearance rate (CCr). The combined treatment group showed the lowest F4/80+ and CD68+ expressions. The expression of Bcl-2 in the combined treatment group was higher than those in VD3 group and the EPO group, while Bax's expression goes in the opposite direction.

CONCLUSION

This provides further evidence that VD3 and EPO have beneficial effects in I/R injury via anti-inflammatory and anti-apoptosis pathways. The synergistic protective effect of VD3 and EPO is of profound significance in the development of new strategies for the prevention and treatment of acute kidney injury (AKI).

Vitamin D3 as Potential Treatment Adjuncts for COVID-19

Severe acute respiratory syndrome coronavirus type (SARS-CoV2, also known as COVID-19), which is the latest pandemic infectious disease, constitutes a serious risk to human health. SARS-CoV2 infection causes immune activation and systemic hyperinflammation which can lead to respiratory distress syndrome (ARDS). ARDS victims are characterized by a significant increase in IL-6 and IL-1. Macrophage activation, associated with the “cytokine storm”, promotes the dysregulation of the innate immunity. So far, without vaccines or specific therapy, all efforts to design drugs or clinical trials are worthwhile. Vitamin D and its receptor vitamin D receptor (VDR) exert a critical role in infections due to their remarkable impact on both innate and adaptive immune responses and on the suppression of the inflammatory process. The protective properties of vitamin D supplementation have been supported by numerous observational studies and by meta-analysis of clinical trials for prevention of viral acute respiratory infection. In this review, we compare the mechanisms of the host immune response to SARS-CoV2 infection and the immunomodulatory actions that vitamin D exerts in order to consider the preventive effect of vitamin D supplementation on SARS-CoV2 viral infection.

The efficacy of a compounded micronutrient supplement on the incidence, duration, and severity of the common cold: A pilot randomized, double-blinded, placebo-controlled trial

Purpose

Viral upper respiratory infections are associated with significant health and economic impact. This study sought to determine the efficacy of routine immune system micronutrient supplementation on the incidence, duration and severity of common cold symptoms.

Methods

This pilot study was a randomized, double-blinded, placebo-controlled trial of N = 259 with asymptomatic participants aged 18 to 65 in two cold seasons of 2016 and 2017. The treatment group received an immune system targeted micronutrient caplet, while the placebo group received a micronized cellulose caplet externally identical to the treatment caplet. Weekly surveys were sent electronically to participants to document common cold incidence, duration and severity. Primary statistical results were obtained using mixed-effects logistic regressions to account for longitudinal measurements for participants.

Results

The odds of acquiring an upper respiratory infection, adjusted for potential confounders, was estimated to be 0.74 times lower in the treatment group (p = 0.14). The odds of reporting specific symptoms were statistically lower in the treatment arm compared to the placebo arm for runny nose (OR = 0.53, p = 0.01) and cough (OR = 0.51, p = 0.04). Shorter durations of runny nose and cough were also observed in the treatment arm compared to placebo (both p < 0.05). There was no significant difference in severity of symptoms in either group. The observed proportion of reported cold symptoms in the treatment group was lower compared to the placebo group between late January and February in two consecutive cold seasons. Given the physical, workplace and economic impact of upper respiratory infections, this low cost and low risk intervention should be further studied with more robust investigation and meticulous experimental design.

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.

Endometriosis and food habits: Can diet make the difference?

Endometriosis is a chronic, inflammatory, estrogenic-dependent disease characterized by the presence of endometrial glands outside the uterine cavity, affecting approximately 2%–10% of women in reproductive age and 30%–50% of women in general. Despite the high prevalence of the disease, not much is known about etiology, possible risk factors, and an adequate and satisfactory therapy. In the past years, many studies have focused on food intake (nutrients and food groups) and on its possible correlation with endometriosis, demonstrating how diet could be identified as a possible risk factor. Comprehensive searches in the largest medical information databases (Medline-PubMed, Embase, Lilacs, and Cochrane Library) were conducted using the Medical Subject Heading terms “diet,” “food,” “nutrition,” “fatty acids,” vitamins,” “fruit,” “vegetables,” “coffee,” “caffeine,” “fish,” “soy food,” “dairy products,” “tea,” “curcumin” combined with “endometriosis.” Purpose of this review is to revise the literature, in order to determine potential modifiable risk factors of the disease.

Oral spray wintertime vitamin D3 supplementation has no impact on inflammation in Gaelic footballers

Vitamin D inadequacy [total 25(OH)D <50 nmol/L] is widespread in athletes. The biologically active metabolite, 1,25-dihydroxyvitamin D, may be involved in regulating inflammation although in vitro findings have not been consistently replicated in human intervention trials. This study, conducted at a latitude of 55°N, aimed to assess inflammatory biomarkers in Gaelic footballers before and after a wintertime vitamin D₃ intervention. Samples from a 12-week double-blind, randomized, placebo-controlled trial, in which 42 Gaelic footballers received 3000 IU (75 μg) vitamin D₃ daily or placebo via oral spray solutions, were analysed for a range of inflammatory biomarkers. Cytokines (interleukin-8 and tumor necrosis factor-α), cathelicidin and high sensitivity C-reactive protein were quantified by multiplex assay, enzyme-linked immunosorbent assay and clinical biochemistry, respectively. White blood cell, lymphocyte, and neutrophil concentrations were determined by full blood profile. Data on total 25-hydroxyvitamin D, measured by LC-MS/MS, were available from the previous study. Vitamin D₃ supplementation significantly increased mean total 25-hydroxyvitamin D concentrations from 47 to 84 nmol/L (P = 0.006); yet this had no effect on white blood cell count (P = 0.699), lymphocyte (P = 0.694), neutrophil (P = 0.594), interleukin-8 (P = 0.334), tumor necrosis factor-α (P = 0.587), cathelicidin (P = 0.745) or high sensitivity C-reactive protein concentration (P = 0.621) compared to placebo. 12-weeks vitamin D₃ supplementation did not impact the immune profile of Gaelic footballers. This is likely because biomarkers were within their respective normal range or at a concentration similar to that of the general population at baseline. Future studies are encouraged to use inflammation as their primary outcome measure and recruit athletes at risk of compromised immunity.

25 Hydroxyvitamin D Deficiency and Its Relationship to Autoimmune Thyroid Disease in the Elderly

Background: Low 25(OH) vitamin D levels have been associated with several autoimmune diseases and recently with autoimmune thyroiditis (AT). The aim of the study was to investigate the association of AT with low 25(OH) vitamin D levels in the elderly. Methods: One hundred sixty-eight elderly subjects (mean age: 81.6 ± 9.4 years) were enrolled. Serum levels of 25(OH) vitamin D, anti-thyroid peroxidase (TPO-Ab), anti-thyroglobulin (TG-Ab) antibodies, free triiodothyronine (FT3), free thyroxine (FT4) and thyroid stimulating hormone (TSH) were measured. Results: The prevalence of AT was significantly higher in subjects with vitamin D deficiency (25(OH) vitamin D < 20 ng/mL) when compared with subjects with normal 25(OH) vitamin D (25(OH) vitamin D ≥ 20 ng/mL) levels (28% vs. 8%, respectively, p = 0.002). Patients with AT and vitamin D deficiency had a comparable hormonal profile compared to patients with AT and vitamin D sufficiency in terms of TSH (p = 0.39), FT3 (p = 0.30), FT4 (p = 0.31), TG-Ab (0.44) and TPO-Ab (0.35). Interestingly, a significant correlation between 25(OH) vitamin D and TPO-Ab (r = −0.27, p = 0.03) and FT3 (r = 0.35, p = 0.006) has been found in subjects with AT while no correlation was found between 25(OH) vitamin D levels and TG-Ab (r = −0.15, p = 0.25), TSH (r = −0.014, p = 0.09) and FT4 (r = 0.13, p = 0.32). Conclusions: These findings suggest that vitamin D deficiency was significantly associated with AT in the elderly. Therefore, the screening for AT should be suggested in subjects with vitamin D deficiency.

Vitamin D Status and Supplementation Practices in Elite Irish Athletes: An Update from 2010/2011

Vitamin D deficiency is a global health concern that is prevalent in Ireland. The vitamin D status of elite Irish athletes following implementation of a revised supplementation policy in 2010/2011 has not been explored to date. This study aimed to assess the vitamin D status of elite Irish athletes participating in high-profile sports and establish if equatorial travel, supplementation and/or sunbed use predict vitamin D status. Across Ireland, blood samples (n = 92) were obtained from cricketers (n = 28), boxers (n = 21) and women’s rugby sevens players (n = 43) between November 2013 and April 2015. Total 25-hydroxyvitamin D (25(OH)D) concentrations were quantified using LC-MS/MS. Parathyroid hormone and adjusted calcium concentrations were measured by clinical biochemistry. Athletes completed a questionnaire that queried equatorial travel, supplementation and sunbed use. Vitamin D sufficiency (25(OH)D >50 nmol/L) was evident in 86% of athletes. Insufficiency (31–49 nmol/L) and deficiency (<30 nmol/L) was present in only 12% and 2% of athletes respectively. On average, athletes from all sport disciplines were vitamin D sufficient and 25% reported vitamin D supplementation which was a significant positive predictor of vitamin D status, (OR 4.31; 95% CI 1.18–15.75; p = 0.027). Equatorial travel and sun bed use were reported in 47% and 16% of athletes respectively however these factors did not predict vitamin D status (both p > 0.05). Although different cohorts were assessed, the overall prevalence of vitamin D insufficiency/deficiency was 55% in 2010/2011 compared with only 14% in 2013/2015. Targeted supplementation is highly effective in optimising vitamin D status, negating the need for blanket-supplementation in elite cohorts.

Novel CD8+ T-Cell Subsets Demonstrating Plasticity in Patients with Inflammatory Bowel Disease

BACKGROUND

Distinct CD8+ T-cell subsets such as interleukin-17-expressing Tc17 and Foxp3-expressing Tcreg are functionally similar to CD4+ T cells. Though CD4+ T cells are dysregulated in patients with inflammatory bowel disease (IBD), CD8+ T cells are not well investigated. Vitamin D is an environmental factor which influences T-cell subsets. We assessed the prevalence of CD8+ T-cell subsets among peripheral blood mononuclear cells (PBMC) and lamina propria mononuclear cells (LPMC) of patients with Crohn's disease, patients with ulcerative colitis, and healthy controls. We then tested the effect of 1α,25-dihydroxyvitamin D3 on CD8+ T-cell subsets.

METHODS

A total of 73 patients with Crohn's disease, 49 patients with ulcerative colitis, and 47 healthy controls were studied. LPMC or PBMC were isolated and flow cytometry was performed. CD3+ T cells, isolated from PBMC, were cultured with or without 1α,25-dihydroxyvitamin D3, before flow cytometry.

RESULTS

In LPMC, the prevalence of Tcreg was higher in patients with IBD (P < 0.05), whereas Tc17 were higher in patients with ulcerative colitis compared with patients with Crohn's disease and healthy controls (P < 0.05). In PBMC, both Tcreg and Tc17 were higher in patients with IBD (P < 0.01). Double-expressing interferon-γ+ interleukin-17+ and Foxp3+ interleukin-17+ CD8+ T cells were also identified indicating possible CD8+ plasticity. 1α,25-dihydroxyvitamin D3 decreased interferon-γ-expressing Tc1 (P < 0.05), but had no effect on Tc17 or Tcreg.

CONCLUSIONS

The prevalence of novel CD8+ T-cell subsets is altered in patients with IBD. Double-expressing cells indicate plasticity and were identified in patients with IBD. Vitamin D may have a limited effect on CD8+ T cells by decreasing interferon-γ expression.

Serum Vitamin D Depends Less on Latitude Than on Skin Color and Dietary Intake During Early Winter in Northern Europe

OBJECTIVES

To evaluate if dietary vitamin D intake is adequate for sufficient vitamin D status during early winter in children living in Sweden, irrespective of latitude or skin color.

METHODS

As part of a prospective, comparative, 2-center intervention study in northern (63°N) and southern (55°N) Sweden, dietary intake, serum 25-hydroxyvitamin D (S-25(OH) D), associated laboratory variables, and sociodemographic data were studied in 5 to 7-year-old children with fair and dark skin in November and December.

RESULTS

Two hundred six children with fair/dark skin were included, 44/41 and 64/57 children in northern and southern Sweden, respectively. Dietary vitamin D intake was higher in northern than southern Sweden (P = 0.001), irrespective of skin color, partly due to higher consumption of fortified foods, but only met 50-70% of national recommendations (10 μg/day). S-25(OH) D was higher in northern than southern Sweden, in children with fair (67 vs 59 nmol/L; P < 0.05) and dark skin (56 vs 42 nmol/L; P < 0.001). S-25(OH) D was lower in dark- than fair-skinned children at both sites (P < 0.01), and below 50 nmol/L in 40 and 75% of dark-skinned children in northern and southern Sweden, respectively.

CONCLUSIONS

Insufficient vitamin D status was common during early winter in children living in Sweden, particularly in those with dark skin. Although, higher dietary vitamin D intake in northern than southern Sweden attenuated the effects of latitude, a northern country of living combined with darker skin and vitamin D intake below recommendations are important risk factors for vitamin D insufficiency.

Modulation of the immune response to respiratory viruses by vitamin D

Background: Vitamin D deficiency has been shown to be independently associated with increased risk of viral acute respiratory infection (ARI) in a number of observational studies, and meta-analysis of clinical trials of vitamin D supplementation for prevention of ARI has demonstrated protective effects. Several cellular studies have investigated the effects of vitamin D metabolites on immune responses to respiratory viruses, but syntheses of these reports are lacking. Scope: In this article, we review the literature reporting results of in vitro experiments investigating immunomodulatory actions of vitamin D metabolites in human respiratory epithelial cells infected with respiratory viruses. Key findings: Vitamin D metabolites do not consistently influence replication or clearance of rhinovirus, respiratory syncytial virus (RSV) or influenza A virus in human respiratory epithelial cell culture, although they do modulate expression and secretion of type 1 interferon, chemokines including CXCL8 and CXCL10 and pro-inflammatory cytokines, such as TNF and IL-6. Future research: More studies are needed to clarify the effects of vitamin D metabolites on respiratory virus-induced expression of cell surface markers mediating viral entry and bacterial adhesion to respiratory epithelial cells.

The pleiotropic effects of vitamin D in gynaecological and obstetric diseases: an overview on a hot topic

The traditionally recognized role of vitamin D consists in the regulation of bone metabolism and calcium-phosphorus homeostasis but recently a lot of in vitro and in vivo studies recognized several “noncalcemic” effects of vitamin D metabolites. Accumulating evidence suggests that the metabolic pathways of this vitamin may play a key role in the developing of gynaecological/obstetric diseases. VDR-mediated signalling pathways and vitamin D levels seem to (deeply) affect the risk of several gynaecological diseases, such as polycystic ovary syndrome (PCOS), endometriosis, and ovarian and even breast cancer. On the other hand, since also the maternal-fetal unit is under the influence of vitamin D, a breakdown in its homeostasis may underlie infertility, preeclampsia, and gestational diabetes mellitus (GDM). According to our literature review, the relationship between vitamin D and gynaecological/obstetric diseases must be replicated in future studies which could clarify the molecular machineries behind their development. We suggest that further investigation should take into account the different serum levels of this vitamin, the several actions which arise from the binding between it and its receptor (taking into account its possible polymorphism), and finally the interplay between vitamin D metabolism and other hormonal and metabolic pathways.

A combination dual-sized microparticle system modulates dendritic cells and prevents type 1 diabetes in prediabetic NOD mice

We developed a novel poly(lactic-co-glycolic acid)-based, microparticle (MP) system providing concurrent delivery of multiple encapsulated immuno-suppressive factors and antigen, for in vivo conditioning of dendritic cells (DCs) toward a tolerance promoting pathway. Subcutaneous administration prevents onset of type 1 diabetes (T1D) in NOD mice. Two MP sizes were made: phagocytosable MPs were fabricated encapsulating vitamin D3 or insulin B(9-23) peptide, while unphagocytosable MPs were fabricated encapsulating TGF-β1 or GM-CSF. The combination of Vit D3/TGF-β1 MPs confers an immature and LPS activation-resistant phenotype to DCs, and MP-delivered antigen is efficiently and functionally presented. Notably, two subcutaneous injections into 4week old NOD mice using the combination of MPs encapsulating Vit D3, Ins B, TGF-β1 and GM-CSF protected 40% of mice from T1D development, significant in comparison to the control. This work represents one of the first applications of a biomaterial-based, MP vaccine system to successfully prevent autoimmune diabetes.

The application of the open pharmacological concepts triple store (open PHACTS) to support drug discovery research

Integration of open access, curated, high-quality information from multiple disciplines in the Life and Biomedical Sciences provides a holistic understanding of the domain. Additionally, the effective linking of diverse data sources can unearth hidden relationships and guide potential research strategies. However, given the lack of consistency between descriptors and identifiers used in different resources and the absence of a simple mechanism to link them, gathering and combining relevant, comprehensive information from diverse databases remains a challenge. The Open Pharmacological Concepts Triple Store (Open PHACTS) is an Innovative Medicines Initiative project that uses semantic web technology approaches to enable scientists to easily access and process data from multiple sources to solve real-world drug discovery problems. The project draws together sources of publicly-available pharmacological, physicochemical and biomolecular data, represents it in a stable infrastructure and provides well-defined information exploration and retrieval methods. Here, we highlight the utility of this platform in conjunction with workflow tools to solve pharmacological research questions that require interoperability between target, compound, and pathway data. Use cases presented herein cover 1) the comprehensive identification of chemical matter for a dopamine receptor drug discovery program 2) the identification of compounds active against all targets in the Epidermal growth factor receptor (ErbB) signaling pathway that have a relevance to disease and 3) the evaluation of established targets in the Vitamin D metabolism pathway to aid novel Vitamin D analogue design. The example workflows presented illustrate how the Open PHACTS Discovery Platform can be used to exploit existing knowledge and generate new hypotheses in the process of drug discovery.

Levels of 1,25(OH)2D3 for patients with pulmonary tuberculosis and correlations of 1,25(OH)2D3 with the clinical features of TB

BACKGROUND

To determine the 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] concentrations to patients with tuberculosis (TB) and whether it influenced the patient's clinical features.

METHODS

For the first part, a total of 153 healthy adults and 74 patients with pulmonary TB (PTB) were enrolled. Serum concentrations of 1,25(OH)2D3 were determined by liquid chromatography-tandem mass spectroscopy to examine the 1,25(OH)2D3 concentrations of the two groups from the peripheral blood. If there are differences between the two groups, what follow will increase the experimental group numbers to examine the relationship among the 1,25(OH)2D3 concentrations with the numbers of the lesion area, the tubercule bacilli in sputum and the CD4/CD8 ratio of T lymphocytes in the peripheral blood.

RESULTS

In the first part, the 1,25(OH)2D3 concentrations was lower in patients with TB than in those healthy adults [365.9 (SD 235.7) vs. 464.3 (SD 335.6), P<0.05]. In the second part, we increased the sample size to 134 (male 91 cases, female 43 cases). we found that the plasma levels of 1,25(OH)2D3 are not correlated with the numbers of the lesion area and the tubercule bacilli in sputum, but the 1,25(OH)2D3 levels can interact the ratio of CD4/CD8 T lymphocytes, it shows a positive correlation with the ratio of CD4/CD8 T lymphocytes.

CONCLUSIONS

The 1,25(OH)2D3 concentrations in TB patients lower than the healthy adults, it might exist as a risk factor during the development of TB or TB might affect the levels of 1,25(OH)2D3. But the different status vitamin D concentration might not affect the numbers of the lesion area, the tubercule bacilli in sputum. It shows a positive correlation with the ratio of CD4/CD8 T lymphocytes. The study will have a significance value to clinical medicine, but further study will need to study the levels of 1,25(OH)2D3 with the TB.

The effects of calcitriol with calcium carbonate supplementation on inflammatory biomarkers in chronic kidney disease patients' with low vitamin D

INTRODUCTION

Chronic kidney disease (CKD) patients' are at risk of low vitamin D and chronic inflammation. We studied the effect of 12 weeks calcitriol and calcium carbonate supplementation on inflammatory mediators serum; interleukin-6 (IL-6), interleukin-10 (IL-10) and highly sensitive C-reactive protein (hs-CRP).

MATERIAL AND METHODS

A prospective randomized study in CKD stages 2-4 with serum 25-hydroxyvitamin D (25-OHD) levels < 30 ng/ml. Patients were randomized into the Vitamin D + Calcium (Vitamin D + C) or Calcium group. Serums were analyzed at baseline, week 6 and 12.

RESULTS

Fifty patients, median age of 53 (13.5) years were recruited. Their median IL-10 was 13.35 (25.22) pg/ml. At week 12, serum IL-6 was reduced in both groups (p = 0.001), serum IL-10 was maintained in the Vitamin D + C group (p = 0.06) and was reduced in the Calcium group (p = 0.001). CKD-diabetic patients had reduced serum IL-6 in both study groups (p = 0.001) and a reduction was seen in the Vitamin D + C group of the non-diabetics counterparts (p = 0.005). Serum IL-10 was reduced in the Calcium group (p < 0.05) whereas serum 25-OHD rose in both groups, regardless of their diabetic status (p < 0.05).

CONCLUSIONS

Twelve weeks, calcitriol supplementation maintained IL-10, had no effects on hs- CRP and had no additional benefit compared to calcium carbonate in reducing serum IL-6 except in non-diabetics.

The effect of calcium with or without calcitriol supplementation on renal function in patients with hypovitaminosis d and chronic kidney disease

Background:

Hypovitaminosis D (serum 25-OHD < 30 ng/mL) is common in patients with chronic kidney disease (CKD). Vitamin D is believed to involve in the regulation of renin-angiotensin system and may be renoprotective.

Objectives:

To compare the effects of calcium with or without calcitriol on renal function in patients with CKD.

Patients and Methods:

A prospective randomized trial was performed involving patients with stages 2-4 CKD and hypovitaminosis D. Baseline demographics data were taken at baseline. Patients were randomized equally into oral calcitriol plus calcium carbonate (calcitriol group) or calcium carbonate alone (non-calcitriol group). Serum levels of 25-hydroxyvitamin D (25-OHD), 1,25-dihydroxyvitamin D3 (1,25-(OH)2D), creatinine, calcium and urine protein creatinine index (uPCI) were measured at 6 and 12 weeks.

Results:

Fifty (21 Female: 29 Male) patients with CKD with a median age of 53 (22-65) years were recruited. Their median MDRD eGFR (modification of diet in renal disease, estimation of glomerular filtration rate) was 36.0 (15-89) mL/min/1.73 m² with the CKD stage 2 (n = 8, 16%), stage 3 (n = 29, 58%), and stage 4 (n = 13, 26%) respectively. In both study groups serum 25-OHD levels were increased at 12 weeks (P = 0.001), in contrast to serum 1,25-(OH)2D levels which remained unchanged (P > 0.05), serum creatinine and uPCI were also remained unchanged until the end of study (P > 0.05 each). Patients with diabetes had higher serum creatinine (P = 0.01) and lower serum 1,25-(OH)2D (P = 0.02) at baseline. Regardless of the diabetics status, the serum 25-OHD was increased, and 1,25-(OH)2D remained unchanged at 12 weeks in both study groups. At 12 weeks, serum creatinine was decreased in patients with diabetes in the noncalcitriol group (P = 0.03) compared to stabilization of creatinine in the calcitriol group (P > 0.05). Serum calcium was increased, though it was still within the normal range in the calcitriol group (P < 0.001); whereas, in the noncalcitriol group, there was an initial reduction but increased back to baseline (P = 0.007). Urine PCI remained unchanged in both groups.

Conclusions:

We have demonstrated that calcitriol supplementation did not offer any additional benefit to reduce 25-OHD and 1,25-(OH)2D levels over calcium carbonate alone in patients with CKD in this short term study. Overall renal function remained unchanged. However, we found that calcitriol at 0.5 mg daily plus calcium carbonate 500 mg daily could be reno-protective in diabetic nephropathy regardless of their serum 25-OHD levels.

Vitamin D in endometriosis: a causative or confounding factor?

OBJECTIVE

The aim of this paper is to review the evidence from studies that evaluated the relationship between vitamin D and endometriosis.

DESIGN

Comprehensive review.

MATERIALS AND METHODS

Systematic literature search in Medline for relevant publications from 1946 until June 2013.

RESULTS

Endometriosis risk may be influenced by dietary vitamin D intake and plasma hydroxyvitamin D concentration. Vitamin D receptor and vitamin D metabolizing enzymes, 24-hydroxylase and 1-α hydroxylase, are found in the normal cycling endometrium and also in the eutopic and ectopic endometrium of women with endometriosis. The endometrium is a target of 1, 25 dihydroxyvitamin D actions through regulation of specific genes and via immunomodulation. The endometrium in endometriosis expresses dysregulation of some vitamin D enzymes and receptors. If vitamin D and its metabolites are implicated in endometriosis-associated infertility, it is likely through interference with HOXA10 gene expression. The Gc2 phenotype of vitamin D binding protein is prevalent in women with endometriosis and may be implicated in its pathogenesis. In a mouse model, Elocalcitol, a VDR-agonist was shown to reduce the development of endometriotic lesions and recurrence.

CONCLUSION

A biological plausibility for a role of vitamin D, as an immunomodulator and anti-inflammatory agent, in the pathogenesis and treatment of endometriosis is suggested in this article, but is difficult to illustrate due to sparse evidence from human studies limited primarily to case-control studies. A significant knowledge gap precludes the establishment of a clear cause-effect relationship. The intriguing leads presented herein need to be investigated further with placebo-controlled supplementation trials.

Uremia suppresses immune signal-induced CYP27B1 expression in human monocytes

BACKGROUND

Local production of 1,25-dihydroxyvitamin D (1,25(OH)(2)D) regulated by the CYP27B1 enzyme in monocytes contributes to the immunomodulatory effects of vitamin D. Uremia suppresses renal CYP27B1, but its impact on monocytic CYP27B1 is incompletely understood. The present study aimed to elucidate this issue and to define the pathogenic role of p-cresyl sulfate (PCS), indoxyl sulfate (IndS), and fibroblast growth factor 23 (FGF23).

METHODS

Resting or immune (interferon-γ + lipopolysaccharide)-stimulated THP1 cells and monocytes, isolated from healthy donors, were cultured in the presence of either healthy serum, uremic serum, PCS, IndS or FGF23. RNA expression levels for CYP27B1 and cytokines were quantified by RT-PCR and enzymatic CYP27B1 activity was measured 24 h after incubation.

RESULTS

Culturing THP1 cells or human monocytes in the presence of uremic serum led to higher inflammatory cytokine and CYP27B1 expression. Immune signal-induced CYP27B1 expression and activity, conversely, was impaired in the presence of uremic serum. Similar effects were observed in the presence of FGF23, although significance was reached in immune-stimulated cells only. PCS and IndS failed to show any effect.

CONCLUSIONS

Monocytic baseline CYP27B1 expression is increased in uremia, probably reflecting the microinflammatory state. Immune signal-induced CYP27B1 expression, conversely, is impaired in uremic conditions. Elevated FGF23 levels, but not PCS and IndS, may account, at least partly, for the dysregulation of monocytic CYP27B1 in uremia and, as such, may contribute to the high cardiovascular and infectious burden in chronic kidney disease.

Prevalence and severity of vitamin D deficiency in patients with diabetic foot infection

The aim of the present research was to study the prevalence and severity of vitamin D deficiency in patients with diabetic foot infection. Patients were enrolled in two groups: diabetic patients with foot infection (n 125) as cases and diabetic patients without the infection as controls (n 164). Serum 25-hydroxyvitamin D (25(OH)D) was measured by RIA. Data were presented as means and standard deviations unless otherwise indicated and were analysed by SPSS. Results revealed that 25(OH)D (nmol/l) was significantly lower (40·25 (sd 38·35) v. 50·75 (sd 33·00); P < 0·001) in cases than in controls. Vitamin D inadequacy (25(OH)D < 75 nmol/l) was equally common in cases and controls (OR 1·45, 95 % CI 0·8, 3·0; P = 0·32), but cases had a greater risk of vitamin D deficiency (25(OH)D < 50 nmol/l) than controls (OR 1·8, 95 % CI 1·1, 3·0; P = 0·02). Risk of severe vitamin D deficiency (25(OH)D < 25 nmol/l) was significantly higher in cases than in controls (OR 4·0, 95 % CI 2·4, 6·9; P < 0·0001). Age, duration of diabetes and HbA1c were significantly higher in cases than in controls and therefore adjusted to nullify the effect of these variables, if any, on study outcome. The study concluded that vitamin D deficiency was more prevalent and severe in patients with diabetic foot infection. This study opens up the issue of recognising severe vitamin D deficiency (< 25 nmol/l) as a possible risk factor for diabetic foot infections and the need for vitamin D supplementation in such patients for a better clinical outcome. This could be substantiated by similar data from future studies.

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.

Low concentrations of serum 25-hydroxyvitamin D associated with increased risk for chronic bronchitis among US adults

Increasing evidence suggests that vitamin D benefits both innate and adaptive immunity, thereby eliciting an anti-inflammatory effect and reducing the risk of infectious disease. The present study examined the association between serum 25-hydroxyvitamin D (25(OH)D) levels and the risk of chronic bronchitis among US adults. We analysed data from 6872 US adults aged ≥ 20 years who participated in the 2003-6 National Health and Nutrition Examination Survey. Prevalence and OR with 95 % CI of having self-reported chronic bronchitis were estimated by quintiles of 25(OH)D or vitamin D-deficiency status after adjustment for potential confounders. The results showed that the adjusted prevalence of chronic bronchitis ranged from 2.4 (95 % CI 1.4, 3.3) % among adults in the highest quintile of 25(OH)D ( ≥ 30 ng/ml) to 4.1 (95 % CI 2.5, 5.6) % among adults in the lowest quintile ( < 15 ng/ml; P for trend < 0.01). The adjusted OR for chronic bronchitis was 1.85 (95 % CI 1.06, 3.24) in adults with < 15 ng/ml 25(OH)D and 1.77 (95 % CI 1.19, 2.65) in those with 15 to < 20 ng/ml 25(OH)D compared with adults with ≥ 30 ng/ml 25(OH)D. Additionally, the adjusted OR for chronic bronchitis was 1.52 (95 % CI 1.03, 2.26) among adults with vitamin D deficiency ( < 20 ng/ml 25(OH)D) compared with those with ≥ 20 ng/ml 25(OH)D. For every 1 ng/ml increase in 25(OH)D, the likelihood of having chronic bronchitis fell by 2.6 % (P = 0.016). In conclusion, low serum 25(OH)D levels are associated with the increased risk of chronic bronchitis among US adults. The present results provide support for continuing research on the role of vitamin D in lung diseases.

Nuclear hormone 1α,25-dihydroxyvitamin D3 elicits a genome-wide shift in the locations of VDR chromatin occupancy

A global understanding of the actions of the nuclear hormone 1α,25-dihydroxyvitamin D₃ (1α,25(OH)₂D₃) and its vitamin D receptor (VDR) requires a genome-wide analysis of VDR binding sites. In THP-1 human monocytic leukemia cells we identified by ChIP-seq 2340 VDR binding locations, of which 1171 and 520 occurred uniquely with and without 1α,25(OH)₂D₃ treatment, respectively, while 649 were common. De novo identified direct repeat spaced by 3 nucleotides (DR3)-type response elements (REs) were strongly associated with the ligand-responsiveness of VDR occupation. Only 20% of the VDR peaks diminishing most after ligand treatment have a DR3-type RE, in contrast to 90% for the most growing peaks. Ligand treatment revealed 638 1α,25(OH)₂D₃ target genes enriched in gene ontology categories associated with immunity and signaling. From the 408 upregulated genes, 72% showed VDR binding within 400 kb of their transcription start sites (TSSs), while this applied only for 43% of the 230 downregulated genes. The VDR loci showed considerable variation in gene regulatory scenarios ranging from a single VDR location near the target gene TSS to very complex clusters of multiple VDR locations and target genes. In conclusion, ligand binding shifts the locations of VDR occupation to DR3-type REs that surround its target genes and occur in a large variety of regulatory constellations.

Vitamin D deficiency and connective tissue disease

Recently, the evidence linking vitamin D status as a potential environmental factor affecting autoimmune disease prevalence continues to accumulate. Beyond that the traditional known metabolic activities, vitamin D has been shown to modulate the immune system and has anti-inflammatory properties. The immune-regulatory role of vitamin D affects both the innate and adaptive immune responses contributing to the immune-tolerance of self-structures. Vitamin D deficiency skews the immunologic response towards loss of tolerance. Serum levels of vitamin D have been found to be significantly lower in several autoimmune or immune-mediated diseases than in the healthy population. Experimental animal models and clinical studies show that 1,25-dihydroxyvitamin D3 or vitamin D receptor (VDR) agonists can either prevent or suppress symptoms of type 1 diabetes, experimental autoimmune encephalomyelitis, rheumatoid arthritis, systemic lupus erthyematosus and inflammatory bowel disease. The heading aims at reviewing the complex immune-regulatory role of vitamin D from the cellular and humoral level through animal models of autoimmune rheumatic diseases and representing the known contribution of vitamin D in the pathogenesis of connective tissue diseases. Increased vitamin D intakes might reduce the incidence and severity of autoimmune disorders besides reducing the rate of osteoporotic bone fracture.

Role of vitamin D in immune responses and autoimmune diseases, with emphasis on its role in multiple sclerosis

Vitamin D is a seco-steroid involved in calcium and phosphorus metabolism, and bone formation and mineralization, through binding to a specific nuclear receptor, vitamin D receptor (VDR). Besides its well-established functions on bone health, multiple lines of evidence have indicated the immunomodulatory roles of vitamin D. Vitamin D can affect both innate and adaptive immunity, and prevent autoimmune responses efficiently. Vitamin D regulates the immune responses by suppressing T cell proliferation and modulating macrophage functions. Epidemiological studies have shown that vitamin D deficiency is associated with multiple diseases such as rickets and cancer. Moreover, associations between vitamin D and autoimmune diseases have been confirmed in multiple sclerosis (MS), rheumatoid arthritis (RA), etc. The present review mainly summarized the recent findings on the immunomodulatory role of vitamin D in various disorders, with special focus on its role in MS, an autoimmune disease of the nervous system.

Vitamin D insufficiency: implications for the immune system

Chronic kidney disease (CKD) is characterized by a loss of kidney function and dysregulation of vitamin D metabolism. Well known are the defects in final activation of vitamin D to 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)], resulting in renal osteodystrophy. However, in recent years, 1,25(OH)(2)D(3) has been identified as having effects far beyond calcium and bone metabolism. In this review, specific attention is given to the effects of 1,25(OH)(2)D(3) on the immune system and the implications of vitamin D deficiency, a feature of many patients with CKD, on immune function.

Why dialysis patients need combination therapy with both cholecalciferol and a calcitriol analogs

The roles of vitamin D, mediated through its conversion to 1,25-dihydroxyvitamin D(3) (calcitriol), have been expanded recently through new knowledge about the range of tissues capable of activating it and the breadth of the genes under its regulatory control. This basic science together with the fact that numerous studies across North America are revealing that vitamin D insufficiency/deficiency (as defined by 25-OH-D levels <30 ng/ml) is extremely common (>80%) in dialysis patients are indicative that these patients have two vitamin D-related problems that require different treatment regimens. Combinations of vitamin D(3) (cholecalciferol) or vitamin D(2) (ergocalciferol) and an active calcitriol analog should be used to treat their vitamin D deficiency and their calcitriol hormone insufficiency, respectively. This mini-review provides the case for combination therapy.

Vitamin D in health and disease: an insight into traditional functions and new roles for the 'sunshine vitamin'

Vitamin D is unique among the vitamins in that man can synthesise it via the action of UV radiation upon the skin. This combined with its ability to act on specific target tissues via vitamin D receptors (VDR) make its classification as a steroid hormone more appropriate. While vitamin D deficiency is a recognised problem in some northern latitude countries, recent studies have shown that even in sunny countries, such as Australia, vitamin D deficiency may be more prevalent than first thought. Vitamin D is most well known for its role in bone health; however, the discovery of VDR on a wide variety of tissue types has also opened up roles for vitamin D far beyond traditional bone health. These include possible associations with autoimmune diseases such as multiple sclerosis and inflammatory bowel diseases, cancer, CVD and muscle strength. First, this paper presents an overview of the two sources of vitamin D: exposure to UVB radiation and food sources of vitamin D, with particular focus on both Australian and international studies on dietary vitamin D intake and national fortification strategies. Second, the paper reviews recent epidemiological and experimental evidence linking vitamin D and its role in health and disease for the major conditions linked to suboptimal vitamin D, while identifying significant gaps in the research and possible future directions for research.

Pretreatment of vitamin D3 ameliorates lung and muscle injury induced by reperfusion of bilateral femoral vessels in a rat model

BACKGROUND

Peripheral arterial occlusive disease (PAOD) is a challenge in peripheral vascular disease. Clinical observations show reperfusion of occluded vessels may cause compartment syndrome or remote organ injury. Less well known is the role of vitamin D3 in tissue injury; therefore, we attempted to determine whether vitamin D3 could alleviate local and remote organ injury induced by reperfusion of occluded vessels in animal models.

METHODS

Twenty-four male Sprague-Dawley rats were randomized into four groups: saline + sham, saline + I/R, vitamin D3 + sham, and vitamin D3 + I/R group. After pretreatment for 5 d, the animals designed to I/R injury were subjected to 3 h of ischemia induced by bilateral femoral arteries clamp, followed by reperfusion of the vessels for 3 h on d 6. Left lung and left anterior tibial muscle tissue were harvested for wet/dry weight ratio and histopathologic analysis. Blood was collected for analysis of urea nitrogen (BUN), creatinine (Cr), aspartate aminotransferase (AST), alanine aminotransferase (ALT), tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), ionized calcium levels, and heme oxygenase-1 (HO-1).

RESULTS

Compared with the saline + sham group, there was a significant increase in plasma IL-6 level in both saline + I/R and vitamin D3 + I/R groups and muscle, lung wet/dry weight ratio in the saline + I/R group (P < 0.05). Compared with the saline + I/R group, there was a significant decrease in plasma IL-6 level, muscle and lung wet/dry weight ratio in both vitamin D3 + sham and vitamin D3 + I/R groups, and leukocyte HO-1 expression in vitamin D3 + sham group (P < 0.05). Compared with the vitamin D3 + sham group, there was a significant increase in plasma IL-6 levels in the vitamin D3 + I/R group, and leukocyte HO-1 expression in vitamin D3 + sham group (P < 0.05). BUN, Cr, AST, ALT, TNF-α, ionized calcium levels did not differ significantly among the groups.

CONCLUSIONS

Pretreatment of vitamin D3 ameliorates the systemic IL-6 levels, lung and muscle injury induced by ischemia followed by reperfusion of bilateral occluded vessels in a rat model.

Is vitamin D deficiency involved in the immune reconstitution inflammatory syndrome?

Background

About 20–30% of persons with HIV infection, especially those living in countries with limited resources, experience an immune reconstitution inflammatory syndrome (IRIS) after starting antiretroviral treatment. The active form of vitamin D, 1,25-dihydroxyvitamin D, is a key player in the clearance of pathogens and influences the level of inflammation and macrophage activation.

Presentation of the hypothesis

We hypothesize that low availability of 1,25-dihydroxyvitamin D, either due to vitamin D deficiency or due to polymorphisms in the vitamin D receptor or in its activating/inactivating enzymes, contributes to the appearance of IRIS. Furthermore, drug interactions with the enzymatic pathways of vitamin D could favour the development of IRIS.

Testing the hypothesis

Our hypothesis could be explored by a case-control study to assess the prevalence of vitamin D deficiency in HIV-infected patients on antiretroviral treatment who develop and do not develop IRIS.

Implications of the hypothesis

If the role of vitamin D in IRIS is confirmed, we would be able to screen patients at risk for IRIS by screening for vitamin D deficiency. After confirmation by means of a clinical trial, vitamin D supplementation could be a cheap and safe way to reduce the incidence of IRIS.

Regulation of vitamin D homeostasis: implications for the immune system

Vitamin D homeostasis in the immune system is the focus of this review. The production of both the activating (25- and 1alpha-hydroxylase) and the metabolizing (24-hydroxylase) enzymes by cells of the immune system itself, indicates that 1,25(OH)(2)D(3) can be produced locally in immune reaction sites. Moreover, the strict regulation of these enzymes by immune signals is highly suggestive for an autocrine/paracrine role in the immune system, and opens new treatment possibilities.

Vitamin D and human health: lessons from vitamin D receptor null mice

The vitamin D endocrine system is essential for calcium and bone homeostasis. The precise mode of action and the full spectrum of activities of the vitamin D hormone, 1,25-dihydroxyvitamin D [1,25-(OH)(2)D], can now be better evaluated by critical analysis of mice with engineered deletion of the vitamin D receptor (VDR). Absence of a functional VDR or the key activating enzyme, 25-OHD-1alpha-hydroxylase (CYP27B1), in mice creates a bone and growth plate phenotype that mimics humans with the same congenital disease or severe vitamin D deficiency. The intestine is the key target for the VDR because high calcium intake, or selective VDR rescue in the intestine, restores a normal bone and growth plate phenotype. The VDR is nearly ubiquitously expressed, and almost all cells respond to 1,25-(OH)(2)D exposure; about 3% of the mouse or human genome is regulated, directly and/or indirectly, by the vitamin D endocrine system, suggesting a more widespread function. VDR-deficient mice, but not vitamin D- or 1alpha-hydroxylase-deficient mice, and man develop total alopecia, indicating that the function of the VDR and its ligand is not fully overlapping. The immune system of VDR- or vitamin D-deficient mice is grossly normal but shows increased sensitivity to autoimmune diseases such as inflammatory bowel disease or type 1 diabetes after exposure to predisposing factors. VDR-deficient mice do not have a spontaneous increase in cancer but are more prone to oncogene- or chemocarcinogen-induced tumors. They also develop high renin hypertension, cardiac hypertrophy, and increased thrombogenicity. Vitamin D deficiency in humans is associated with increased prevalence of diseases, as predicted by the VDR null phenotype. Prospective vitamin D supplementation studies with multiple noncalcemic endpoints are needed to define the benefits of an optimal vitamin D status.

Is there convincing biological or behavioral evidence linking vitamin D deficiency to brain dysfunction?

Vitamin D insufficiency is common in the United States; the elderly and African-Americans are at particularly high risk of deficiency. This review, written for a broad scientific readership, presents a critical overview of scientific evidence relevant to a possible causal relationship between vitamin D deficiency and adverse cognitive or behavioral effects. Topics discussed are 1) biological functions of vitamin D relevant to cognition and behavior; 2) studies in humans and rodents that directly examine effects of vitamin D inadequacy on cognition or behavior; and 3) immunomodulatory activity of vitamin D relative to the proinflammatory cytokine theory of cognitive/behavioral dysfunction. We conclude there is ample biological evidence to suggest an important role for vitamin D in brain development and function. However, direct effects of vitamin D inadequacy on cognition/behavior in human or rodent systems appear to be subtle, and in our opinion, the current experimental evidence base does not yet fully satisfy causal criteria. Possible explanations for the apparent inconsistency between results of biological and cognitive/behavioral experiments, as well as suggested areas for further research are discussed. Despite residual uncertainty, recommendations for vitamin D supplementation of at-risk groups, including nursing infants, the elderly, and African-Americans appear warranted to ensure adequacy.