Vitamin D3 down-regulates monocyte TLR expression and triggers hyporesponsiveness to pathogen-associated molecular patterns

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.

Severe Vitamin D Deficiency May be an Additional Cofactor for the Occurrence of Alcoholic Steatohepatitis

BACKGROUND

Among its pleiotropic effects, vitamin D may protect the liver from fibrosis and/or inflammation. However, the impact of vitamin D on liver pathology in hepatitis C remains unclear, and very few studies including alcoholic patients with liver pathologies have been performed. Here we compared the levels of 25-OH vitamin D in the blood of alcoholic patients with the occurrence of alcoholic steatohepatitis (ASH) or bridging fibrosis.

METHODS

One hundred and one alcoholic patients were included. All the patients received a liver biopsy, and the levels of 25-OH vitamin D were evaluated with the Liaison 25-OH vitamin D assay. Logistic regression analyses were performed to obtain predictive factors of liver histology.

RESULTS

Among alcoholic patients, 40.6% presented ASH and 39.6% presented bridging fibrosis. A severe deficiency in 25-OH vitamin D (<10 ng/ml) was seen in 60.4% of patients. This deficiency was frequent in patients with ASH (85.4%) and in those with bridging fibrosis (80%) but was independently associated only with ASH (odds ratio = 8.46 [95% confidence interval 2.05 to 34.89], p = 0.003).

CONCLUSIONS

In alcoholic patients, a severe deficiency in 25-OH vitamin D was independently associated with the occurrence of ASH.

Vitamin D: Immuno-modulation and tuberculosis treatment

Tuberculosis (TB) is a major global health problem and often coincides with vitamin D deficiency. High doses of vitamin D were widely used to treat TB during the pre-antibiotic era. Vitamin D exerts its action through vitamin D receptor (VDR), and VDR gene polymorphisms are associated with susceptibility or resistance to tuberculosis as well as sputum smear and culture conversion during anti-TB treatment. In-vitro studies have revealed that 1,25-dihydroxyvitamin D3 enhances innate immunity by increased expression of various antimicrobial peptides, including cathelicidin, and induction of autophagy of the infected cells thus restricts the intracellular growth of Mycobacterium tuberculosis in macrophages. On the other hand, vitamin D has been shown to suppress the pro-inflammatory cytokine response and enhance the anti-inflammatory response. Supplementation with vitamin D in concert with treatment for TB may be beneficial with respect to minimizing the excessive tissue damage that occurs during the active stage of tuberculosis disease. Several clinical trials have evaluated vitamin D supplementation as an adjunct therapy in the treatment for tuberculosis. However, results are conflicting, owing to variations in dose regimens and outcomes. Further investigations are needed to find the optimal concentration of vitamin D for supplementation with standard anti-TB drugs to optimize treatment, which could help to effectively manage both drug-sensitive and drug-resistant tuberculosis.

A vitamin D analog inhibits Th2 cytokine- and TGFβ -induced periostin production in fibroblasts: a potential role for vitamin D in skin sclerosis

Scleroderma is an autoimmune disease characterized by extracellular matrix deposition and inflammation. Topical vitamin D analogs have been reported as effective treatments for scleroderma. We previously reported that a matricellular protein, periostin (POSTN), contributes to pathogenesis of scleroderma as POSTN knockout mice were resistant to bleomycin (BLM)-induced scleroderma. We investigated whether a vitamin D analog affects the expression of POSTN in dermal fibroblasts and in a BLM-induced scleroderma model. The vitamin D analog, maxacalcitol (22-oxacalcitriol [OCT]), was applied to dermal fibroblasts and POSTN expression was measured. The effect of OCT on Th2 cytokine- and TGFβ-induced POTSN and Collagen 1 α 1 (Col1A1) expression was also assessed. In vivo, OCT was administered to BLM-induced scleroderma model and outcomes were determined by dermal thickness, collagen density and POSTN expression. Treatment with OCT significantly decreased POSTN expression in dermal fibroblasts. Th2 cytokine- and TGFβ-induced expression of POSTN and Col1A1 was also suppressed by OCT. In vivo, OCT administration decreased the density of collagen bundles and POSTN expression in a BLM-induced scleroderma model. In addition to the previously reported immunosuppressive effect, the vitamin D analog OCT might be effective to treat scleroderma, in part through inhibition of Th2 cytokine- and TGFβ-induced POSTN expression.

Can we translate vitamin D immunomodulating effect on innate and adaptive immunity to vaccine response?

Vitamin D (VitD), which is well known for its classic role in the maintenance of bone mineral density, has now become increasingly studied for its extra-skeletal roles. It has an important influence on the body’s immune system and modulates both innate and adaptive immunity and regulates the inflammatory cascade. In this review our aim was to describe how VitD might influence immune responsiveness and its potential modulating role in vaccine immunogenicity. In the first instance, we consider the literature that may provide molecular and genetic support to the idea that VitD status may be related to innate and/or adaptive immune response with a particular focus on vaccine immunogenicity and then discuss observational studies and controlled trials of VitD supplementation conducted in humans. Finally, we conclude with some knowledge gaps surrounding VitD and vaccine response, and that it is still premature to recommend “booster” of VitD at vaccination time to enhance vaccine response.

Vitamin D and its effects on glucose homeostasis, cardiovascular function and immune function

In recent years there has been increasing interest in the non-skeletal effects of vitamin D. It has been suggested that vitamin D deficiency may influence the development of diabetes, cardiovascular dysfunction and autoimmune diseases. This review focuses on the current knowledge of the effects of vitamin D and its deficiency on cardiovascular function, glucose homeostasis and immune function, with a particular focus on children. Although, there is good evidence to show that there is an association between vitamin D deficiency and an abnormality of the above systems, there is little evidence to show that vitamin D supplementation leads to an improvement in function, especially in childhood.

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

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

Bimodal Influence of Vitamin D in Host Response to Systemic Candida Infection-Vitamin D Dose Matters

Vitamin D level is linked to susceptibility to infections, but its relevance in candidemia is unknown. We aimed to investigate the in vivo sequelae of vitamin D3 supplementation in systemic Candida infection. Implicating the role of vitamin D in Candida infections, we showed that candidemic patients had significantly lower 25-OHD concentrations. Candida-infected mice treated with low-dose 1,25(OH)2D3 had reduced fungal burden and better survival relative to untreated mice. Conversely, higher 1,25(OH)2D3 doses led to poor outcomes. Mechanistically, low-dose 1,25(OH)2D3 induced proinflammatory immune responses. This was mediated through suppression of SOCS3 and induction of vitamin D receptor binding with the vitamin D-response elements in the promoter of the gene encoding interferon γ. These beneficial effects were negated with higher vitamin D3 doses. While the antiinflammatory effects of vitamin D3 are well described, we found that, conversely, lower doses conferred proinflammatory benefits in Candida infection. Our study highlights caution against extreme deviations of vitamin D levels during infections.

Lower vitamin D levels are associated with increased risk of early-onset neonatal sepsis in term infants

OBJECTIVE

To evaluate the effect of vitamin D levels on early-onset sepsis (EOS) in term infants.

STUDY DESIGN

Fifty term infants with clinical and laboratory findings of EOS (study group) and 50 healthy infants with no signs of clinical/laboratory infection (control group) were enrolled. Blood was drawn at the time of admission during the first 3 postnatal days of life in both groups for measurement of 25-hydroxyvitamin D (25-OHD) levels.

RESULT

Maternal and neonatal 25-OHD levels (22.2/8.6 ng ml(-1), respectively) in the study group were significantly lower than those of the control group (36.2/19 ng ml(-1), respectively, P<0.001). A positive correlation was detected between maternal and neonatal 25-OHD levels. Severe vitamin D deficiency was significantly more common in the sepsis group.

CONCLUSION

Lower maternal and neonatal 25-OHD levels are associated with EOS. These data suggest that adequate vitamin D supplementation during pregnancy may be helpful to prevent EOS in term neonates.

Verneuil's disease, innate immunity and vitamin D: a pilot study

BACKGROUND

Verneuil's disease is a chronic inflammatory skin disease of the follicles in apocrine glands rich area of the skin (axillary, inguinal, anogenital) and is associated with a deficient skin innate immunity. It is characterized by the occurrence of nodules, abscesses, fistulas, scars. Recently, vitamin D has been shown to stimulate skin innate immunity.

OBJECTIVE

The primary objective of the study was to assess whether Verneuil's disease was associated with vitamin D deficiency. The secondary objective was to determine whether vitamin D supplementation could improve inflammatory lesions.

METHODS

First, 25(OH) vitamin D3 serum levels in patients with Verneuil's disease followed at Nantes University Hospital were compared to those of healthy donors from the French Blood Bank. Then, a pilot study was conducted in 14 patients supplemented with vitamin D according to their vitamin D level at baseline at months 3 and 6. The endpoints at 6 months were decreased by at least 20% in the number of nodules and in the frequency of flare-ups.

RESULTS

Twenty-two patients (100%) had vitamin D deficiency (level <30 ng/mL) of whom 36% were severely deficient (level <10 ng/mL), having correlation with the disease severity (P = 0.03268) vs. 20 controls with vitamin D deficiency (91%) of whom 14% were severely deficient. In 14 patients, the supplementation significantly decreased the number of nodules at 6 months (P = 0.01133), and the endpoints were achieved in 79% of these patients. A correlation between the therapeutic success and the importance of the increase in vitamin D level after supplementation was observed (P = 0.01099).

CONCLUSION

Our study shows that Verneuil's disease is associated with a major vitamin D deficiency, correlated with the disease severity. It suggests that vitamin D could significantly improve the inflammatory nodules, probably by stimulating the skin innate immunity. A larger randomized study is needed to confirm these findings.

Vitamin D and colon cancer

Calcitriol, 1α, 25-dihydroxyvitamin D₃ (1,25 (OH)₂D₃), the most active form of vitamin D, is a pleotropic hormone with a wide range of biological activities. Due to its ability to regulate calcium and phosphate metabolism, 1,25D₃ plays a major role in bone health. In addition, 1,25D₃ binds to the vitamin D receptor and thereby regulates the expression of a number of genes which control growth, differentiation and survival of cancer cells. In agreement, the levels of vitamin D₃ appear to be an essential determinant for the development and progression of colon cancer and supplementation with vitamin D₃ is effective in suppressing intestinal tumorigenesis in animal models. Vitamin D₃ has been estimated to lower the incidence of colorectal cancer by 50%, which is consistent with the inverse correlation between dietary vitamin D₃ intake or sunlight exposure and human colorectal cancer. Several studies confirmed that increasing vitamin D₃ lowers colon cancer incidence, reduces polyp recurrence, and that sufficient levels of vitamin D₃ are associated with better overall survival of colon cancer patients. Vitamin D regulates the homeostasis of intestinal epithelium by modulating the oncogenic Wnt signaling pathway and by inhibiting tumor-promoting inflammation. Both activities contribute to the ability of 1,25D₃ to prevent the development and progression of colon cancer.

Differential effect of vitamin D on NOD2- and TLR-induced cytokines in Crohn's disease

Accumulating evidence implicates defective innate immunity in the pathogenesis of Crohn's disease (CD). Ineffectual NOD2 (nucleotide-binding oligomerization domain 2) is the most common susceptibility gene contributing to CD. Vitamin D (vD), a potent modulator of innate and adaptive immunity, induces NOD2 gene expression and its downstream function. We hypothesized that the hormonal form of vD (1,25D) could beneficially modulate innate immune function in CD. Using peripheral mononuclear cells and monocyte-derived dendritic cells (Mo-DCs) from CD, it was found that 1,25D decreased Toll-like receptor (TLR)-induced cytokine production and enhanced cytokine levels induced by muramyl dipeptide (MDP), the NOD2 ligand. 1,25D increased the synergistic effect provided by NOD2 and TLR co-activation on interleukin (IL)-10, IL-23, and tumor necrosis factor-alpha (TNF-α). Whereas 1,25D inhibits Mo-DC TLR-induced cytokines, co-stimulation of NOD2 results in increased IL-10 and IL-23. IL-12p70 was completely abrogated by 1,25D. 1,25D similarly modulated cytokine production by immune cells in ulcerative colitis patients and healthy controls. Mo-DCs from CD patients heterozygous for NOD2 mutations had a response similar to those from patients without NOD2 mutations. Immune cells from patients homozygous for the 1007 fs mutation were unresponsive to MDP and 1,25D. Our in vitro data support 1,25D as a potential modulator of immunity. However, these results cannot be extrapolated to CD patients without further controlled studies.

Inflammation and vitamin D: the infection connection

INTRODUCTION

Inflammation is believed to be a contributing factor to many chronic diseases. The influence of vitamin D deficiency on inflammation is being explored but studies have not demonstrated a causative effect.

METHODS

Low serum 25(OH)D is also found in healthy persons exposed to adequate sunlight. Despite increased vitamin D supplementation inflammatory diseases are increasing. The current method of determining vitamin D status may be at fault. The level of 25(OH)D does not always reflect the level of 1,25(OH)2D. Assessment of both metabolites often reveals elevated 1,25(OH)2D, indicating abnormal vitamin D endocrine function.

FINDINGS

This article reviews vitamin D's influence on the immune system, examines the myths regarding vitamin D photosynthesis, discusses ways to accurately assess vitamin D status, describes the risks of supplementation, explains the effect of persistent infection on vitamin D metabolism and presents a novel immunotherapy which provides evidence of an infection connection to inflammation.

CONCLUSION

Some authorities now believe that low 25(OH)D is a consequence of chronic inflammation rather than the cause. Research points to a bacterial etiology pathogenesis for an inflammatory disease process which results in high 1,25(OH)2D and low 25(OH)D. Immunotherapy, directed at eradicating persistent intracellular pathogens, corrects dysregulated vitamin D metabolism and resolves inflammatory symptoms.

Micronutrients and dengue

Dengue virus infection is the most widespread mosquito-borne viral infection in humans and has emerged as a serious global health challenge. In the absence of effective treatment and vaccine, host factors including nutritional status, which may alter disease progression, need investigation. The interplay between nutrition and other infections is well-established, and modulation of nutritional status often presents a simple low-cost method of interrupting transmission, reducing susceptibility, and/or ameliorating disease severity. This review examines the evidence on the role of micronutrients in dengue virus infection. We found critical issues and often inconsistent results across studies; this finding along with the lack of sufficient literature in this field have limited our ability to make any recommendations. However, vitamins D and E have shown promise in small supplementation trials. In summary, the role of micronutrients in dengue virus infection is an exciting research area and needs to be examined in well-designed studies with larger samples.

Lower regional and temporal ultraviolet exposure is associated with increased rates and severity of inflammatory bowel disease hospitalisation

BACKGROUND

In the northern hemisphere, the incidence of inflammatory bowel diseases (IBD) has a north-south gradient, suggesting a link between ultraviolet (UV) exposure or vitamin D status and the pathogenesis of IBD.

AIM

To test the association of UV exposure with the rates and severity of IBD hospitalisation.

METHODS

We conducted a retrospective nationwide analysis of 649 932 Crohn's disease (CD), 384 267 ulcerative colitis (UC), and 288 894 297 non-IBD hospitalisations in the US between 1998 and 2010. Mean UV exposure was assigned to each hospitalisation using surface measures from the National Oceanic and Atmospheric Administration. Relative rates across UV exposures were estimated for IBD hospitalisations, prolonged hospitalisations, bowel surgeries and deaths.

RESULTS

Among IBD patients, lower UV exposures had increased hospitalisation rates for CD (217.8 vs. 182.5 per 100 000 overall hospitalisations with low and very high UV, respectively; P trend <0.001) and UC (123.2 vs. 113.8 per 100 000; P trend = 0.033). Low UV groups had greater relative rates of prolonged hospitalisations [CD: 1.13, 95% confidence interval (CI) 1.07-1.19; UC: 1.21, 95% CI 1.13-1.30], bowel surgeries (CD: 1.24, 95% CI 1.16-1.32; UC: 1.21, 95% CI 1.09-1.33), and CD deaths (CD: 1.76, 95% CI 1.14-2.71; UC: 1.24, 95% CI 0.92-1.67). Among non-IBD patients, low UV was associated with prolonged hospitalisations (1.09; 95% CI 1.07-1.11) and deaths (1.13; 95% CI 1.09-1.17), but not bowel surgeries (1.01; 95% CI 0.99-1.03).

CONCLUSIONS

Lower ultraviolet exposure is associated with greater rates of hospitalisation, prolonged hospitalisation and the need for bowel surgery in IBD. This trend for bowel surgery was not seen with non-IBD encounters.

Vitamin D deficiency causes defective resistance to Aspergillus fumigatus in mice via aggravated and sustained inflammation

Background

Vitamin D plays an important role in pulmonary resistance and immunity, and its deficiency has been linked to various respiratory infections. Little is known about the effect of vitamin D deficiency on host pulmonary defense to Aspergillus fumigatus (A. fumigatus).

Methods

Mice raised on vitamin D sufficient or deficient diets were infected intratracheally with A. fumigatus conidia. Mortality, fungal growth, weight loss and lung histology were monitored. Alveolar macrophages (AMs) were stimulated with A. fumigatus conidia in vitro. The kinetics of pro-inflammatory cytokines (TNF-α, IL-1β and IL-6), chemokines (CXCL1, CCL3), and pattern recognition receptors (Toll-like receptor [TLR] 2, TLR 4 and dectin-1) expression in the lungs and AMs were measured.

Results

Upon A. fumigatus infection, vitamin D deficient mice showed higher mortality, greater fungal load, and more weight loss than its sufficient counterparts. Vitamin D deficient mice demonstrated aggravated and prolonged histological evidence of lung inflammation as well as enhanced BAL cell counts, dominated by neutrophils after A. fumigatus inoculation. Increased basal levels of pro-inflammatory cytokines in the lungs and AMs from naïve vitamin D deficient mice were observed. Upon A. fumigatus exposure, vitamin D deficiency led to enhanced and sustained expression of TNF-α, IL-1β, IL-6, CXCL1 and CCL3 both in vivo and in vitro. Up-regulation of TLR2, TLR4 and dectin-1was observed in the lungs and AMs from vitamin D deficient mice both at baseline and after A. fumigatus exposure.

Conclusions

Vitamin D deficiency causes defective pulmonary resistance to A. fumigatus in mice, possibly by the enhanced basal expression of pattern recognition receptors and pro-inflammatory cytokines, which induced excessive inflammatory response in response to A. fumigatus challenge.

Calcitriol May Down-Regulate mRNA Over-Expression of Toll-Like Receptor-2 and -4, LL-37 and Proinflammatory Cytokines in Cultured Human Keratinocytes

Background

Although vitamin D analogs have been used in the topical treatment of psoriasis, their mechanisms of action are not well understand. Calcitriol, the hormonally active vitamin D3 metabolite, has been demonstrated to exert immunomodulatory effects in the skin by down-regulating the expression of Toll-like receptors (TLRs) and proinflammatory cytokines.

Objective

We investigated the effects of calcitriol on the expression of TLR2, TLR4, antimicrobial peptide LL-37, and proinflammatory cytokines in cultured human keratinocytes.

Methods

The mRNA expression levels of TLR2, TLR4, tumor necrosis factor α (TNF-α), interleukin (IL)-1β and LL-37 in cultured human keratinocytes were measured by real-time polymerase chain reaction (PCR) and reverse transcription (RT). Furthermore, we measured supernatant TNF-α levels by an enzyme-linked immunosorbent assay (ELISA) to confirm the effects of calcitriol on TLR2 and TLR4.

Results

As measured by RT-PCR and real-time PCR, calcitriol was found to suppress the lipopolysaccharide- and ultraviolet B radiation-mediated induction of expression of TLRs, LL-37 and proinflammatory cytokines such as TNF-α and IL-1β in normal human keratinocytes. The supernatant TNF-α levels measured by ELISA were also suppressed after treatment with calcitriol.

Conclusion

Calcitriol may down-regulate inflammatory stated over-expression of LL-37 and proinflammatory cytokines.

Vitamin D as an anti-microbial and anti-inflammatory therapy for Cystic Fibrosis

Cystic fibrosis (CF) is characterized by chronic infection and inflammation in the airways that lead to progressive lung damage and early death. Current anti-inflammatory therapies are limited by extensive adverse effects or insufficient efficacy. There is a large body of studies indicating beneficial anti-microbial and anti-inflammatory properties of vitamin D. Since most patients with CF present with vitamin D deficiency, and serum vitamin D levels demonstrate a positive correlation with lung function and negative correlation with airway inflammation and infection, correcting vitamin D deficiency may be an attractive therapeutic strategy in CF. The function of vitamin D is intricately tied to its metabolism, which may be impaired at multiple steps in patients with CF, with a potential to limit the efficacy of vitamin D supplementation. It is likely that the aforementioned beneficial properties of vitamin D require supplementation with doses of vitamin D markedly higher than those recommended to maintain proper bone function. This review will illustrate the potential for supplementation with vitamin D or its metabolites to modulate inflammation and improve defence against chronic infection in CF lung, as well as appropriate vitamin D supplementation strategies for improving lung function in CF.

Vitamin D receptor agonists: suitable candidates as novel therapeutic options in autoimmune inflammatory myopathy

The primary aim in the treatment of autoimmune inflammatory myopathies (IMs) is to recover muscle function. The presence of immune/inflammatory cell infiltrates within muscle tissues represents the common feature of different IM subtypes, albeit a correlation between muscular damage extent and inflammation degree is often lacking. Treatments for IMs are based on life-long immunosuppressive therapy, with the well known adverse effects; recovery is incomplete for many patients. More effective therapies, with reduced side-effects, are highly desirable. Vitamin D receptor (VDR) agonists emerge to retain pleiotropic anti-inflammatory properties, since they regulate innate and adaptive immunity by switching the immune response from proinflammatory T helper 1 (Th1) type to tolerogenic T helper 2 (Th2) type dominance. In skeletal muscle cells less hypercalcemic VDR ligands target powerful mediators of inflammation, such as TNFα and TNFα driven paths, without affecting immune or muscle cells viability, retaining the potentiality to counteract Th1 driven overreactivity established by the self-enhancing inflammatory loop between immune and skeletal muscle cells. This review summarizes those features of VDR agonists as candidates in future treatment of IM.

1,25-Dihydroxyvitamin D3 up-regulates TLR10 while down-regulating TLR2, 4, and 5 in human monocyte THP-1

In humans, there are ten Toll-like receptors (TLRs), among which TLR10 is the only orphan receptor whose function is unknown. In this study, we examined the effects of IFN-γ, LPS and 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] on TLR10 expression of human monocyte THP-1 and compared them with those of other surface TLRs such as TLR2, 4 and 5 to differentiate TLR10 from other TLRs. Surface TLR10 expression on THP-1 was significantly enhanced by the addition of IFN-γ or LPS in a fashion similar to that of other TLRs. However, TLR10 expression was differentially regulated by 1,25(OH)2D3. Surface TLR10 expression on THP-1 was significantly enhanced at 24h, reaching approximately two times the control level at 48h after treatment with 100nM 1,25(OH)2D3, while that of TLR2, 4 and 5 decreased gradually in response to treatment over time. 1,25(OH)2D3 at concentrations above 1nM markedly enhanced surface TLR10 expression, but concentrations below 1nM did not. TLR10 mRNA expression was also increased by 1,25(OH)2D3. We next screened for putative binding sites of nuclear vitamin D receptor (VDR) and its counterpart RXR-α within promoter of TLR genes using a transcription factor binding site-prediction program. The results revealed that TLR10 is the only receptor among the tested TLRs that has both a VDR and RXR-α binding site within its proximal promoter. To identify possible involvement of VDR/RXR in the 1,25(OH)2D3-induced TLR10 up-regulation, we engaged the VDR synthesis inhibitor, dexamethasone, and the RXR antagonist, 1,8-dihydroxyanthraquinone. We found that TLR10 up-regulation was significantly blocked with pre-treatment of these inhibitors. These findings indicate that surface TLR10 expression is differentially regulated by 1,25(OH)2D3 and mainly regulated at the transcriptional level via VDR/RXR-α. Overall, results presented herein suggest that TLR10 functions differently from other known surface TLRs under certain circumstances. Further study using primary cells is necessary to confirm the results of the present study.

Diagnostic Value of 25-Hydroxyvitamin D Level and New Cytokines in Neonatal Sepsis

The aim of this study was to evaluate diagnostic value of 25-hydroxyvitamin D level, Upar, IL-33 and ST2 in comparison with C-reactive protein, TNF-α and Interleukin-6 in neonatal sepsis. A total of 106 term babies were included 20 of whom were the control group. We used only data of high probable sepsis with blood culture positive infants, therefore 46 infants were excluded. Blood was collected from infants from the first day of sepsis (1.value) and 48–72 hours later (2.value). There were significant differences between the controls and sepsis (1.value) for 25-hydroxyvitamin D levels (35±19ng/ml and 69±7.5ng/ml, p=0.01), for IL-33 levels (90±34 ng/ml and 412±170 ng/ml, p=0.01), for sST2 levels (453±44 ng/ml and 4120±2720ng/ml, p=0.01), for sUpar levels (2.1±1.3 ng/ml and 11.4 ± 5.2 ng/ml, p=0.01), respectively. There were significant differences between sepsis (1.value) and sepsis (2.value.) with reference to 25-hydroxyvitamin D, IL-33, sST2, and suPAR levels, respectively. In the light of these results, it may be suggested that 25-hydroxyvitamin D level, upar, IL-33 and ST2 can be used as an acute phase reactant like C-reactive protein, TNF-α and Interleukin-6 in diagnosis of neonatal sepsis.

Impact of vitamin D on immune function: lessons learned from genome-wide analysis

Immunomodulatory responses to the active form of vitamin D (1,25-dihydroxyvitamin D, 1,25D) have been recognized for many years, but it is only in the last 5 years that the potential role of this in normal human immune function has been recognized. Genome-wide analyses have played a pivotal role in redefining our perspective on vitamin D and immunity. The description of increased vitamin D receptor (VDR) and 1α-hydroxylase (CYP27B1) expression in macrophages following a pathogen challenge, has underlined the importance of intracrine vitamin D as key mediator of innate immune function. It is now clear that both macrophages and dendritic cells (DCs) are able to respond to 25-hydroxyvitamin D (25D), the major circulating vitamin D metabolite, thereby providing a link between the function of these cells and the variations in vitamin D status common to many humans. The identification of hundreds of primary 1,25D target genes in immune cells has also provided new insight into the role of vitamin D in the adaptive immune system, such as the modulation of antigen-presentation and T cells proliferation and phenotype, with the over-arching effects being to suppress inflammation and promote immune tolerance. In macrophages 1,25D promotes antimicrobial responses through the induction of antibacterial proteins, and stimulation of autophagy and autophagosome activity. In this way variations in 25D levels have the potential to influence both innate and adaptive immune responses. More recent genome-wide analyses have highlighted how cytokine signaling pathways can influence the intracrine vitamin D system and either enhance or abrogate responses to 25D. The current review will discuss the impact of intracrine vitamin D metabolism on both innate and adaptive immunity, whilst introducing the concept of disease-specific corruption of vitamin D metabolism and how this may alter the requirements for vitamin D in maintaining a healthy immune system in humans.

Vitamin D and diabetes mellitus

The vitamin D endocrine system in now recognized as subserving a wide range of fundamental biological functions in cell differentiation, inhibition of cell growth as well as immunomodulation. Both forms of immunity, namely adaptive and innate, are regulated by 1,25(OH)2D3. The immune-modulatory properties of vitamin D suggest that it could play a potential therapeutic role in prevention of type 1 diabetes mellitus (T1DM). It is postulated that large doses of vitamin D supplementation may influence the pattern of immune regulation and subsequent progression to T1DM in a genetically susceptible individual. More studies are required to substantiate the relation between T1DM and vitamin D/vitamin D analogues in the pattern of immune regulations in susceptible individuals. In type 2 diabetes mellitus (T2DM), vitamin D may influence both insulin secretion and sensitivity. An inverse relationship between T2DM and vitamin D is postulated from cross-sectional and prospective studies, though conclusive proof is as yet lacking. Available studies differ in their design and in the recommended daily allowances (RDA) of vitamin D in non-skeletal diseases and β-cell function. Large, well designed, controlled, randomized interventional studies on the potential role of vitamin D and calcium in prevention and management of T2DM are required to clarify the relationship between vitamin D and glucose homeostasis in T2DM.

Vitamin D receptor polymorphism FokI is associated with spontaneous idiopathic preterm birth in an Israeli population

OBJECTIVE

The active form of vitamin D (1,25[OH]2D3) has been established to have potent anti-proliferative, immuno-modulatory, and anti-microbial action in addition to its effects on bone. The nuclear vitamin D receptor (VDR) is expressed in the placenta-decidua, regulating genes associated with implantation and implantation immuno-tolerance. If VDR polymorphisms regulate VDR functionality at the placenta-decidua interface, VDR genotypes may be involved in idiopathic preterm birth (PTB).

STUDY DESIGN

Maternal and fetal (umbilical cord) blood samples from 33 Jewish and Arab mothers with PTB of a singleton neonate were compared to 98 samples from Jewish and Arab maternal and fetal blood samples from full-term, uncomplicated singleton births. Maternal age and ethnicity were comparable between groups. PCR amplification/digestion identified the VDR SNPs: FokI, ApaI, TaqI, and BsmI.

RESULTS

Allele frequency for the FokI VDR in maternal blood samples from preterm births (but not umbilical cord samples) was significantly different (p=0.01) from that in maternal and umbilical cord blood samples from full-term singleton births, with an odds ratio for FokI carriers of 3.317 (95% CI, 1.143, 9.627) for preterm birth. The FokI VDR variant may therefore be a maternal risk trait for PTB among these women.

CONCLUSION

This study may support a future platform for the study of vitamin D during pregnancy and treatment of selective target populations with vitamin D and/or VDR "tissue-specific therapeutic intervention" for prevention of PTB.

Vitamin D deficiency and risk of acute lung injury in severe sepsis and severe trauma: a case-control study

Background

The aim of this study was to determine the association between 25-hydroxyvitamin D (25-OHD) levels at the onset of critical illness and the development of acute lung injury/acute respiratory distress syndrome (ALI/ARDS) in patients with sepsis or trauma.

Methods

We performed two nested case-control studies of 478 patients with sepsis and trauma with or without ALI/ARDS admitted to the medical, surgical and trauma ICUs of a tertiary-care center. Cases consisted of patients with either sepsis or trauma and ALI/ARDS; controls consisted of equivalent numbers of matched patients with either sepsis or trauma alone. We measured serum 25-OHD levels the morning after ICU admission and used multivariable regression to assess the relationship between 25-OHD and diagnosis of ALI/ARDS during the first four ICU days, controlling for age, gender, diabetes, smoking status and season.

Results

25-OHD levels did not differ between cases with ALI/ARDS and controls in either the sepsis or trauma cohorts. Using a conditional logistic regression model, sepsis patients during the winter season with higher 25-OHD levels were more likely to develop acute lung injury (odds ratio 1.68, 95% confidence interval of 1.05 to 2.69, P = 0.03). This association did not hold for the trauma cohort in either season. Sepsis and trauma patients had a lower risk of hospital mortality at higher 25-OHD levels but neither relationship reached significance. Higher one-year mortality after trauma was associated with lower 25-OHD levels (HR 0.50, CI 0.35,0.72 P = 0.001).

Conclusions

Serum 25-OHD measured early after admission to intensive care is not associated with the development of acute lung injury, hospital or one-year mortality in critically ill patients with sepsis although lower 25-OHD levels were associated with higher one-year mortality in patients with severe trauma.

Association of low serum 25-hydroxyvitamin D levels and sepsis in the critically ill

OBJECTIVE

We hypothesized that deficiency in 25-hydroxyvitamin D prior to hospital admission would be associated with sepsis in the critically ill.

DESIGN

Two-center observational study of patients treated in medical and surgical ICUs.

SETTING

Two hundred nine medical and surgical intensive care beds in two teaching hospitals in Boston, MA.

PATIENTS

Three thousand three hundred eighty-six patients, 18 years old or older, in whom 25-hydroxyvitamin D was measured prior to hospitalization between 1998 and 2011.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

: Preadmission 25-hydroxyvitamin D was categorized as deficiency in 25-hydroxyvitamin D (≤ 15 ng/mL), insufficiency (15-30 ng/mL), and sufficiency (≥ 30 ng/mL). The primary outcome was sepsis as defined by International Classification of Diseases, 9th Edition, Clinical Modification and validated by the 2001 Society of Critical Care Medicine/European Society of Intensive Care Medicine, American College of Chest Physicians, American Thoracic Society, and Surgical Infection Society international sepsis definitions conference guidelines. Logistic regression examined the presence of sepsis 3 days prior to critical care initiation to 7 days after critical care initiation. Adjusted odds ratios were estimated by multivariable logistic regression models. Preadmission 25-hydroxyvitamin D deficiency is predictive for the risk of sepsis. In the full cohort, 25-hydroxyvitamin D deficiency is a significant predictor for the risk of International Classification of Diseases, 9th Edition, Clinical Modification-defined sepsis following multivariable adjustment, including age, gender, race, type (surgical vs medical), and Deyo-Charlson index (adjusted odds ratio, 1.51 [95% CI, 1.17-1.94]; p = 0.001) relative to patients with 25-hydroxyvitamin D sufficiency. In a subset of cohort patients enriched for those with International Classification of Diseases, 9th Edition, Clinical Modification-diagnosed sepsis (n = 444), preadmission 25-hydroxyvitamin D deficiency is a significant predictor for the risk of conference guideline-defined sepsis following multivariable adjustment, including age, gender, race, type (surgical vs medical), and Acute Physiology and Chronic Health Evaluation II (adjusted odds ratio, 2.05 [95% CI, 1.19-3.52]; p = 0.009) relative to patients with 25-hydroxyvitamin D sufficiency. Furthermore, in cohort patients with International Classification of Diseases, 9th Edition, Clinical Modification-defined sepsis (n = 568), the multivariable adjusted risk of 90-day mortality was 1.6-fold higher in those with preadmission 25-hydroxyvitamin D values in the insufficient and deficient range, compared with those with preadmission vitamin D sufficiency (adjusted odds ratio, 1.63 [95% CI, 1.11-2.39]; p = 0.01).

CONCLUSION

25-hydroxyvitamin D deficiency prior to hospital admission is a significant predictor of sepsis in the critically ill. Additionally, patients with sepsis who are not vitamin D sufficient have an increased risk of mortality following critical care initiation.

Vitamin D deficiency is associated with mortality in patients with advanced liver cirrhosis

BACKGROUND

Chronic liver disease is the fifth most common cause of mortality in Europe. Recently, vitamin D deficiency has been associated with an increased risk of mortality in the general population. As patients with advanced liver disease frequently exhibit vitamin D deficiency, we assessed for a possible association of vitamin D deficiency with survival in a cohort of patients with advanced liver disease.

METHODS

Sixty-five patients with liver cirrhosis (median age, 58 years; range, 19-76 years; 66% male; Child-Pugh stage C, 46%) were included in our prospective single-centre survival study. Serum 25-hydroxyvitamin D concentrations were measured by chemiluminescence immunoassay. The optimal cut-off was determined using receiver operating characteristic (ROC) and Kaplan-Meier analysis. Chi-square statistics and multivariate binary logistic regression analysis were also conducted.

RESULTS

Median serum vitamin D levels were 8·2 ng/mL (range <4·0-95·8 ng/mL). Overall, 48% of patients (31/65) died during a 24-month follow-up period. ROC analysis determined a vitamin D level of 6·0 ng/mL as optimal cut-off for discriminating survivors from nonsurvivors. Kaplan-Meier analysis of survival confirmed low vitamin D levels as significant predictor of death (P = 0·012). Finally, multivariate analysis identified low vitamin D levels (OR = 6·3; 95% CI, 1·2-31·2; P = 0·012) and MELD scores (OR = 1·4; 95% CI, 1·2-1·7; P < 0·001) as independent predictors of survival.

CONCLUSION

Low vitamin D levels are associated with increased mortality in patients with advanced liver disease. Thus, serum levels of vitamin D might represent a critical marker of survival in advanced liver cirrhosis.

Vitamin D and the Immune System from the Nephrologist's Viewpoint

Vitamin D and its analogues are widely used as treatments by clinical nephrologists, especially when treating chronic kidney disease (CKD) patients with secondary hyperparathyroidism. As CKD progresses, the ability to compensate for elevations in parathyroid hormone (PTH) and fibroblast growth factor-23 and for decreases in 1,25(OH)₂D₃ becomes inadequate, which results in hyperphosphatemia, abnormal bone disorders, and extra-skeletal calcification. In addition to its calciotropic effect on the regulation of calcium, phosphate, and parathyroid hormone, vitamin D has many other noncalciotropic effects, including controlling cell differentiation/proliferation and having immunomodulatory effects. There are several immune dysregulations that can be noted when renal function declines. Physicians need to know well both the classical and nonclassical functions of vitamin D. This review is an analysis from the nephrologist's viewpoint and focuses on the relationship between the vitamin D and the immune system, together with vitamin's clinical use to treat kidney diseases.

Vitamin D and Its Role as a Protective Factor in Allergy

The relationship between vitamin D status and asthma has been subject to several studies in the last decade. Epidemiological data suggest that incidence of asthma and atopic diseases increased significantly in most Westernized countries. The significant variation between countries suggests that besides genetic factors, environmental aspects play a role in the pathogenesis of atopy. The prevalence of hypovitaminosis D is high in many industrialized countries. In addition to its relationship with bone metabolism, vitamin D is recognized as an immunomodulator, with important effects on both adaptive and innate immunity. Correlations between vitamin D status and asthma have been formulated, with a considerable interest in assessing whether this vitamin protects against or reduces asthma morbidity. In this review, we discuss recent findings regarding vitamin D status throughout Europe and its influence over asthma and allergic rhinitis prevalence. Geographical latitude and dietary habits may explain the lower prevalence of allergic disease in Albania. We also consider the effects of vitamin D supplementation in allergic disease. Several clinical trials are under way and their results are needed in order to make definitive recommendations about the optimal dose of vitamin D for prevention and treatment of asthma and allergic disease.

Dietary vitamin D deficiency in rats from middle to old age leads to elevated tyrosine nitration and proteomics changes in levels of key proteins in brain: implications for low vitamin D-dependent age-related cognitive decline

In addition to the well-known effects of vitamin D (VitD) in maintaining bone health, there is increasing appreciation that this vitamin may serve important roles in other organs and tissues, including the brain. Given that VitD deficiency is especially widespread among the elderly, it is important to understand how the range of serum VitD levels that mimic those found in humans (from low to high) affects the brain during aging from middle age to old age. To address this issue, 27 male F344 rats were split into three groups and fed isocaloric diets containing low (100 IU/kg food), control (1000 IU/kg food), or high (10,000 IU/kg food) VitD beginning at middle age (12 months) and continued for a period of 4-5 months. We compared the effects of these dietary VitD manipulations on oxidative and nitrosative stress measures in posterior brain cortices. The low-VitD group showed global elevation of 3-nitrotyrosine compared to control and high-VitD-treated groups. Further investigation showed that this elevation may involve dysregulation of the nuclear factor κ-light-chain enhancer of activated B cells (NF-κB) pathway and NF-κB-mediated transcription of inducible nitric oxide synthase (iNOS) as indicated by translocation of NF-κB to the nucleus and elevation of iNOS levels. Proteomics techniques were used to provide insight into potential mechanisms underlying these effects. Several brain proteins were found at significantly elevated levels in the low-VitD group compared to the control and high-VitD groups. Three of these proteins, 6-phosphofructokinase, triose phosphate isomerase, and pyruvate kinase, are involved directly in glycolysis. Two others, peroxiredoxin-3 and DJ-1/PARK7, have peroxidase activity and are found in mitochondria. Peptidyl-prolyl cis-trans isomerase A (cyclophilin A) has been shown to have multiple roles, including protein folding, regulation of protein kinases and phosphatases, immunoregulation, cell signaling, and redox status. Together, these results suggest that dietary VitD deficiency contributes to significant nitrosative stress in brain and may promote cognitive decline in middle-aged and elderly adults.

The role of lipid-activated nuclear receptors in shaping macrophage and dendritic cell function: From physiology to pathology

Nuclear receptors are ligand-activated transcription factors linking lipid signaling to the expression of the genome. There is increasing appreciation of the involvement of this receptor network in the metabolic programming of macrophages and dendritic cells (DCs), essential members of the innate immune system. In this review we focus on the role of retinoid X receptor, retinoic acid receptor, peroxisome proliferator-associated receptor γ, liver X receptor, and vitamin D receptor in shaping the immune and metabolic functions of macrophages and DCs. We also provide an overview of the contribution of macrophage- and DC-expressed nuclear receptors to various immunopathologic conditions, such as rheumatoid arthritis, inflammatory bowel disease, systemic lupus erythematosus, asthma, and some others. We suggest that systematic analyses of the roles of these receptors and their activating lipid ligands in immunopathologies combined with complementary and focused translational and clinical research will be crucial for the development of new therapies using the many molecules available to target nuclear receptors.

IRF5, but not TLR4, DEFB1, or VDR, is associated with the risk of ulcerative colitis in a Han Chinese population

OBJECTIVE. IRF5, TLR4, DEFB1, and VDR genetic variations have been associated with ulcerative colitis (UC) in several European patient cohorts. As distinct genetic backgrounds may play a role in different ethnicities, we evaluated the effects of single-nucleotide polymorphisms (SNPs) in these genes and their interactions in UC patients of Han Chinese descent. MATERIAL AND METHODS. DNA samples from 300 UC patients and 302 healthy control subjects from Peking Union Medical College Hospital were genotyped for 14 tag SNPs, which were selected based on haplotype analysis of IRF5, TLR4, DEFB1, and VDR. Multidimensionality reductions were used to explore gene-gene interactions. RESULTS. The only observed association with UC was for IRF5. On an allelic level, SNP rs3807306 was associated with UC risk (p = 6.7 × 10(-3)). On a genotypic level, the CC genotype of SNP rs3807306 (p = 0.03) was associated with protection from UC, and the AA genotype of SNP rs4728142 (p = 7.6 × 10(-3)) was associated with a risk of UC. In the haplotype analysis, GGATT was highly correlated with UC risk (p-Value = 2.0 × 10(-4)). No significant multilocus interactions were detected among these four genes. CONCLUSIONS. Our study confirmed the association of IRF5 with UC in Han Chinese patients. Han Chinese UC patients share part of their genetic susceptibility with Caucasian patients.

Vitamin D₃ derivatives increase soluble CD14 release through ERK1/2 activation and decrease IL-8 production in intestinal epithelial cells

Dysfunction of the innate immune system has been reported to cause intestinal inflammation. Vitamin D3 is known to be an important immune system regulator and exerts anti-inflammatory effects. We investigated in vitro effects of vitamin D3 and its derivatives on the innate immune system in HT-29 cells, a line of human colon adenocarcinoma cells. Among the innate immune-related receptors such as Toll-like receptor (TLR) 1, 2, 4, 6, and CD14 examined by flow cytometry, only CD14 was up-regulated by vitamin D3 derivatives. Release of soluble form CD14 (sCD14) was also increased by vitamin D3 derivatives. The 1α,25-dihydroxy-22-oxavitamin D3 (Oxa-D3) induced-sCD14 release was inhibited by U0126 (a specific inhibitor of extracellular signal-regulated kinase; ERK1/2) but not by SB203580 (a specific inhibitor of p38 MAPK), and ERK1/2 phosphorylation was accelerated by Oxa-D3. These results indicate that Oxa-D3 facilitates the release of sCD14 through ERK1/2 activation. IL-8 production stimulated with LPS was diminished by vitamin D3 derivatives. Recombinant sCD14 also lowered the LPS-stimulated IL-8 production, suggesting neutralization of LPS by sCD14. The anti-inflammatory effect of vitamin D3 derivatives was thus associated with diminution of IL-8 production due to increased release of sCD14.

Beneficial role of vitamin D3 in the prevention of certain respiratory diseases

There is evidence of aberrations in the vitamin D-endocrine system in subjects with respiratory diseases. Vitamin D deficiency is highly prevalent in patients with respiratory diseases, and patients who receive vitamin D have significantly larger improvements in inspiratory muscle strength and maximal oxygen uptake. Studies have provided an opportunity to determine which proteins link vitamin D to respiratory pathology, including the major histocompatibility complex class II molecules, vitamin D receptor, vitamin D-binding protein, chromosome P450, Toll-like receptors, poly(ADP-ribose) polymerase-1, and the reduced form of nicotinamide adenine dinucleotide phosphate. Vitamin D also exerts its effect on respiratory diseases through cell signaling mechanisms, including matrix metalloproteinases, mitogen-activated protein kinase pathways, the Wnt/β-catenin signaling pathway, prostaglandins, reactive oxygen species, and nitric oxide synthase. In conclusion, vitamin D plays a significant role in respiratory diseases. The best form of vitamin D for use in the treatment of respiratory diseases is calcitriol because it is the active metabolite of vitamin D3 and modulates inflammatory cytokine expression. Further investigation of calcitriol in respiratory diseases is needed.

Vitamin D deficiency impacts on expression of toll-like receptor-2 and cytokine profile: a pilot study

Background

Vitamin D is believed to play an important role outside the endocrine system in the regulation of the immune system, and in cellular proliferation and differentiation. The aim of the study was to investigate the impact of vitamin D levels on innate immunity.

Methods

Participants for this prospective, longitudinal study were recruited amongst otherwise healthy staff of a large hospital in Victoria, Australia. Those fulfilling the inclusion criteria, including a vitamin D level of <50 nmol/L, were supplemented. Using flow cytometry, expression of the innate immune receptors TLR2, TLR4 and CD86 was measured on peripheral blood mononuclear cells (PBMCs) collected prior to vitamin D treatment and then at 1 and 3 months. Additonally, PBMCs at each timepoint were stimulated with specific TLR ligands and resultant supernatants were assayed for the cytokines TNFα, IL-6, IFN-α and IP-10.

Results

In participants whose vitamin D level was >100 nmol/L post supplementation (n=11), TLR2 expression on PBMCs increased significantly, with no change noted in TLR4 or CD86 expression. Stimulation of vitamin D deficient samples with TLR ligands produced a number of proinflammatory cytokines, which were significantly reduced upon vitamin D normalisation. In patients whose levels returned to a deficient level at 3 months despite ongoing low-level supplementation, an increase in the pro-inflamamtory state returned. This suggests that vitamin D may play an important role in ensuring an appropriate baseline pro-inflammatory state.

Conclusions

This ex-vivo pilot study adds clinical evidence supporting a possibly important role for vitamin D in innate immunity. If confirmed, this unique clinical study has potentially significant implications for the treatment of a variety of inflammatory conditions, where achieving optimal vitamin D levels may help reduce inflammation.

The pathophysiology of the hygiene hypothesis

There has been a considerable increase in the diagnosis of allergic diseases over the last decades. Prevalence of allergies in high-income countries and urban areas appears higher than in rural environments. While environmental factors like pollution or nutrition can be important, it is more likely that in the end they have a small association with allergies. Childhood infections and exposure to certain microbial antigens on the other hand seem to present a strong negative correlation with allergies, and therefore the increase of the allergic burden in the Western world has been frequently related to a decline of childhood infections giving birth to the "Hygiene Hypothesis". We address the issue with emphasis on the associated pathophysiology tightrope walking between the skepticism of the critics, which cast doubt on it, and the pilgrims' belief of having discovered allergy's Holy Grail.

Vitamin D in allergic disease: shedding light on a complex problem

Vitamin D is unique among nutritional factors because the intake of this special vitamin represents the sum of vitamin D obtained from diet, nutritional supplements, and endogenous production after exposure to sunlight. The current recommended nutritional intake requirements reflect needs based on its established role in calcium absorption and bone health. However, recent studies have revealed that vitamin D has important functions in the immune system and might influence the course of immune-mediated disorders, including atopic dermatitis and asthma. This review discusses the scientific rationale for a role for vitamin D in immune function, gives an update on allergic disease associations with lower vitamin D serum levels, and discusses recent observations relating to vitamin D in immune function.

The beneficial role of vitamin D in obesity: possible genetic and cell signaling mechanisms

The prevalence rates of overweight and obesity are considered an important public issue in the United States, and both of these conditions are increasing among both children and adults. There is evidence of aberrations in the vitamin D-endocrine system in obese subjects. Vitamin D deficiency is highly prevalent in patients with obesity, and many studies have demonstrated the significant effect of calcitriol on adipocytes. Genetic studies have provided an opportunity to determine which proteins link vitamin D to obesity pathology, including the vitamin D receptor, toll-like receptors, the renin-angiotensin system, apolipoprotein E, vascular endothelial growth factor, and poly (ADP-ribose) polymerase-1. Vitamin D also exerts its effect on obesity through cell-signaling mechanisms, including matrix metalloproteinases, mitogen-activated protein kinase pathways, the reduced form of nicotinamide adenine dinucleotide phosphate, prostaglandins, reactive oxygen species, and nitric oxide synthase.

In conclusion, vitamin D may have a role in obesity. The best form of vitamin D for use in the obese individuals is calcitriol because it is the active form of the vitamin D₃ metabolite, its receptors are present in adipocytes, and modulates inflammatory cytokine expression.

The pleiomorphic actions of vitamin D and its importance for children

Knowledge regarding the physiological role and dietary requirements of vitamin D has dramatically expanded over the past several decades. The "new" vitamin D is not only a mediator of calcium homeostasis, it also has important immunomodulatory, antimicrobial, and antiproliferative actions. In spite of the interest in vitamin D as a mediator in many chronic diseases of adulthood such as cancer and type II diabetes, less attention has been given to the implications of the new understanding of vitamin D for child and adolescent health. Recently, rickets caused by vitamin D deficiency is resurging in developed countries. Therefore, pharmacokinetic studies and epidemiologic research that incorporates clinical and functional outcomes are needed to clarify the role of vitamin D in growth and development in Korean children and adolescents and to determine vitamin D dietary requirements.

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

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

1(OH) vitamin D3 supplementation improves the sensitivity of the immune-response during Peg-IFN/RBV therapy in chronic hepatitis C patients-case controlled trial

OBJECTIVE

1,25(OH)2 vitamin D3 can affect immune cells. However, the mechanism responsible for the favorable effects of 1(OH) vitamin D3, which becomes 1,25(OH)2 vitamin D3 in the liver, is not clear. The aim of this study is to analyze the immunological response of 1(OH) vitamin D3 supplementation in CH-C patients.

DESIGN

Forty-two CH-C patients were treated with 1(OH) vitamin D3/Peg-IFNα/RBV. Forty-two case-matched controls were treated with Peg-IFNα/RBV. The expression of Interferon-stimulated genes (ISGs)-mRNA in the liver biopsy samples and JFH-1 replicating Huh-7 cells were quantified by real-time PCR. Ten kinds of cytokines in the plasma were quantified during treatment by using a suspension beads array. A trans-well co-culture system with peripheral blood mononuclear cells (PBMCs) and Huh-7 cells was used to analyze the effect of 1(OH) vitamin D3. The activities of the Th1 response were compared between subjects treated with 1(OH) vitamin D3/Peg-IFN/RBV and those treated with Peg-IFN/RBV therapy alone.

RESULTS

1(OH) vitamin D3/Peg-IFN/RBV treatment could induce rapid viral reduction, especially in IL28B T/T polymorphism. Several kinds of cytokines including IP-10 were significantly decreased after 4 weeks of 1(OH) vitamin D3 treatment (p<0.05). Th1 responses in the subjects treated with 1(OH) vitamin D3/Peg-IFN/RBV were significantly higher than those treated with Peg-IFN/RBV at 12 weeks after Peg-IFN/RBV therapy (p<0.05). The expression of ISGs in the patient's liver biopsy samples was significantly lower than in those treated without 1(OH) vitamin D3 (p<0.05).

CONCLUSION

1(OH) vitamin D3 could improve the sensitivity of Peg-IFN/RBV therapy on HCV-infected hepatocytes by reducing the IP-10 production from PBMCs and ISGs expression in the liver.

1(OH) vitamin D3 supplementation improves the sensitivity of the immune-response during Peg-IFN/RBV therapy in chronic hepatitis C patients-case controlled trial

OBJECTIVE

1,25(OH)2 vitamin D3 can affect immune cells. However, the mechanism responsible for the favorable effects of 1(OH) vitamin D3, which becomes 1,25(OH)2 vitamin D3 in the liver, is not clear. The aim of this study is to analyze the immunological response of 1(OH) vitamin D3 supplementation in CH-C patients.

DESIGN

Forty-two CH-C patients were treated with 1(OH) vitamin D3/Peg-IFNα/RBV. Forty-two case-matched controls were treated with Peg-IFNα/RBV. The expression of Interferon-stimulated genes (ISGs)-mRNA in the liver biopsy samples and JFH-1 replicating Huh-7 cells were quantified by real-time PCR. Ten kinds of cytokines in the plasma were quantified during treatment by using a suspension beads array. A trans-well co-culture system with peripheral blood mononuclear cells (PBMCs) and Huh-7 cells was used to analyze the effect of 1(OH) vitamin D3. The activities of the Th1 response were compared between subjects treated with 1(OH) vitamin D3/Peg-IFN/RBV and those treated with Peg-IFN/RBV therapy alone.

RESULTS

1(OH) vitamin D3/Peg-IFN/RBV treatment could induce rapid viral reduction, especially in IL28B T/T polymorphism. Several kinds of cytokines including IP-10 were significantly decreased after 4 weeks of 1(OH) vitamin D3 treatment (p<0.05). Th1 responses in the subjects treated with 1(OH) vitamin D3/Peg-IFN/RBV were significantly higher than those treated with Peg-IFN/RBV at 12 weeks after Peg-IFN/RBV therapy (p<0.05). The expression of ISGs in the patient's liver biopsy samples was significantly lower than in those treated without 1(OH) vitamin D3 (p<0.05).

CONCLUSION

1(OH) vitamin D3 could improve the sensitivity of Peg-IFN/RBV therapy on HCV-infected hepatocytes by reducing the IP-10 production from PBMCs and ISGs expression in the liver.

Mechanisms of obesity-induced inflammation and insulin resistance: insights into the emerging role of nutritional strategies

Obesity and associated chronic inflammation initiate a state of insulin resistance (IR). The secretion of chemoattractants such as MCP-1 and MIF and of cytokines IL-6, TNF-α, and IL-1β, draw immune cells including dendritic cells, T cells, and macrophages into adipose tissue (AT). Dysfunctional AT lipid metabolism leads to increased circulating free fatty acids, initiating inflammatory signaling cascades in the population of infiltrating cells. A feedback loop of pro-inflammatory cytokines exacerbates this pathological state, driving further immune cell infiltration and cytokine secretion and disrupts the insulin signaling cascade. Disruption of normal AT function is causative of defects in hepatic and skeletal muscle glucose homeostasis, resulting in systemic IR and ultimately the development of type 2 diabetes. Pharmaceutical strategies that target the inflammatory milieu may have some potential; however there are a number of safety concerns surrounding such pharmaceutical approaches. Nutritional anti-inflammatory interventions could offer a more suitable long-term alternative; whilst they may be less potent than some pharmaceutical anti-inflammatory agents, this may be advantageous for long-term therapy. This review will investigate obese AT biology, initiation of the inflammatory, and insulin resistant environment; and the mechanisms through which dietary anti-inflammatory components/functional nutrients may be beneficial.

Estimation of vitamin D levels in patients with pemphigus vulgaris

BACKGROUND

Keratinocyte acantholysis as a result of pathogenic Dsg3-antibodies production by B cells leads to Pemphigus vulgaris (PV). Vitamin D, through its participation in several immune modulatory functions including B cells apoptosis, Th2 cell differentiation, apoptotic enzyme regulation and Tregs functions, may be actively involved in the immune regulation of PV.

OBJECTIVE

To evaluate Vitamin D status in PV patients in comparison to controls in an attempt to determine its role in this autoimmune disease.

METHODS

Using ELISA technique, 25-hydroxyvitamin D (25OHD) was determined for 34 pemphigus vulgaris patients and 20 healthy volunteers. Phosphorus and parathormone were also determined in the patient group.

RESULTS

25OHD was significantly lower in patients than controls (P = 0.008). There was a statistically significant difference between both groups regarding suboptimal Vit. D levels (P = 0.007).

CONCLUSION

Patients with PV have significantly lower serum vitamin D levels in comparison to controls and that these low levels were not related to age, BMI or pattern of sun exposure. The associated Vitamin D insufficiency in patients with PV may possibly exacerbate their disease through various immune related mechanisms.

How important is vitamin D in preventing infections?

Interaction with the immune system is one of the most recently established nonclassic effects of vitamin D (VitD). For many years, this was considered to be limited to granulomatous diseases in which synthesis of active 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) or calcitriol is known to be increased. However, recent reports have supported a role for 1,25(OH)2D3 in promoting normal function of the innate and adaptive immune systems. Crucially, these effects seem to be mediated not only by the endocrine function of circulating calcitriol but also via paracrine (i.e., refers to effects to adjacent or nearby cells) and/or intracrine activity (i.e., refers to a hormone acting inside a cell) of 1,25(OH)2D3 from its precursor 25(OH)D3, the main circulating metabolite of VitD. The ability of this vitamin to influence human immune responsiveness seems to be highly dependent on the 25(OH)D3 status of individuals and may lead to aberrant response to infection or even to autoimmunity in those who are lacking VitD. The potential health significance of this has been underlined by increasing awareness of impaired status in populations across the globe. This review will examine the current understanding of how VitD status may modulate the responsiveness of the human immune system. Furthermore, we discuss how it may play a role in host resistance to common pathogens and how effective is its supplementation for treatment or prevention of infectious diseases in humans.