What is new in vitamin D: 2006–2007

Therapeutic Effects of Vitamin D on Vaginal, Sexual, and Urological Functions in Postmenopausal Women

Recent years have witnessed the emergence of growing evidence concerning vitamin D's potential role in women's health, specifically in postmenopausal women. This evidence also includes its connection to various genitourinary disorders and symptoms. Numerous clinical studies have observed improvements in vulvovaginal symptoms linked to the genitourinary syndrome of menopause (GSM) with vitamin D supplementation. These studies have reported positive effects on various aspects, such as vaginal pH, dryness, sexual functioning, reduced libido, and decreased urinary tract infections. Many mechanisms underlying these pharmacological effects have since been proposed. Vitamin D receptors (VDRs) have been identified as a major contributor to its effects. It is now well known that VDRs are expressed in the superficial layers of the urogenital organs. Additionally, vitamin D plays a crucial role in supporting immune function and modulating the body's defense mechanisms. However, the characterization of these effects requires more investigation. Reviewing existing evidence regarding vitamin D's impact on postmenopausal women's vaginal, sexual, and urological health is the purpose of this article. As research in this area continues, there is a potential for vitamin D to support women's urogenital and sexual health during the menopausal transition and postmenopausal periods.

Vitamin D, exercise, and immune health in athletes: A narrative review

Vitamin D exerts important extra-skeletal effects, exhibiting an exquisite immune regulatory ability, affecting both innate and adaptive immune responses through the modulation of immunocyte function and signaling. Remarkably, the immune function of working skeletal muscle, which is fully recognized to behave as a secretory organ with immune capacity, is under the tight control of vitamin D as well. Vitamin D status, meaning hormone sufficiency or insufficiency, can push toward strengthening/stabilization or decline of immune surveillance, with important consequences for health. This aspect is particularly relevant when considering the athletic population: while exercising is, nowadays, the recommended approach to maintain health and counteract inflammatory processes, “too much” exercise, often experienced by athletes, can increase inflammation, decrease immune surveillance, and expose them to a higher risk of diseases. When overexercise intersects with hypovitaminosis D, the overall effects on the immune system might converge into immune depression and higher vulnerability to diseases. This paper aims to provide an overview of how vitamin D shapes human immune responses, acting on the immune system and skeletal muscle cells; some aspects of exercise-related immune modifications are addressed, focusing on athletes. The crossroad where vitamin D and exercise meet can profile whole-body immune response and health.

Serum vitamin D, calcium, and zinc levels in patients with COVID-19

Background and aim

COVID-19 is a global public health concern. As no standard treatment has been found for it yet, several minerals and vitamins with antioxidants, immunomodulators, and antimicrobials roles can be sufficient for the immune response against the disease. The present study evaluates the serum vitamin D, calcium, and Zinc levels in patients with COVID-19.

Materials & methods

This research is a case–control study performed in May 2020 on 93 patients with COVID-19 hospitalized in a Shoushtar city hospital and on 186 healthy subjects with no symptoms of COVID-19. The serum vitamin D, calcium, and zinc levels were collected and analyzed using correlation coefficient and independent t-test via SPSS 18.

Results

Vitamin D levels had a significant difference between the case and control groups (p = 0.008). Serum calcium and serum zinc levels also had statistically significant differences between the two groups (p < 0.001).

Conclusion

The research results showed that serum zinc, calcium, and vitamin D levels in COVID-19 patients are lower than in the control group. The supplementation with such nutrients is a safe and low-cost measure that can help cope with the increased demand for these nutrients in risk of acquiring the COVID-19 virus.

The Influence of Vitamin D on Neurodegeneration and Neurological Disorders: A Rationale for its Physio-pathological Actions

Vitamin D is a steroid hormone implicated in the regulation of neuronal integrity and many brain functions. Its influence, as a nutrient and a hormone, on the physiopathology of the most common neurodegenerative diseases is continuously emphasized by new studies. This review addresses what is currently known about the action of vitamin D on the nervous system and neurodegenerative diseases such as Multiple Sclerosis, Alzheimer's disease, Parkinson's disease and Amyotrophic Lateral Sclerosis. Further vitamin D research is necessary to understand how the action of this "neuroactive" steroid can help to optimize the prevention and treatment of several neurological diseases.

The expression and methylation status of vitamin D receptor gene in Behcet's disease

INTRODUCTION

Vitamin D has important roles as a natural immune modulator via regulating the expression of genes which have been implicated in the pathophysiology of autoimmune diseases. Vitamin D function and its deficiency have been linked to a wide range of metabolic disorders including disorders of calcium metabolism, malignant, cardiovascular, infectious, neuromuscular, and inflammatory diseases. Environmental factors, genetic factors, and epigenetic changes contribute to Behcet's disease (BD) development. The aim of our study was to analyze the expression level and methylation status of the vitamin D receptor (VDR) gene promoter in the peripheral blood mononuclear cells (PBMCs) of patients with BD.

METHODS

In a case-control study, 48 Iranian Azeri patients with BD and 60 age-, sex- and ethnically-matched healthy controls were included. Venous blood samples were collected and PBMCs were isolated by Ficoll protocol. The DNA and RNA were subsequently extracted. Promoter methylation levels were evaluated by MeDIP-quantitative polymerase chain reaction (qPCR). The expression of VDR was evaluated by real-time PCR.

RESULTS

The results of quantitative real-time PCR analysis showed that the level of VDR expression in patients with BD was significantly lower than the control group (P = .013). There was no significant difference in the level of DNA methylation in the BD and control groups (P > .05). As the results show, the expression level of VDR gene was significantly different between female and male in the patient group (P = .001). VDR gene expression was significantly higher in subjects with phlebitis. No correlation was observed between VDR gene expression rate and BD activity.

CONCLUSION

VDR gene expression decreased in patients with BD. However, there is no suggestion evidence that the expression level of VDR is regulated by a unique DNA methylation mechanism. No correlation exists between VDR gene expression and BD activity.

The molecular and clinical evidence of vitamin D signaling as a modulator of the immune system: Role in Behçet's disease

Various tissues and cell types are the targets of vitamin D. However, the major targets of vitamin D in the immune system are monocytes/macrophages, dendritic cells (DCs), as well as B and T cells. Vitamin D plays an important role in the immune system modulation via regulating the expression of genes that generate pro-inflammatory mediators and inhibiting the proliferation of pro-inflammatory cells, both of which have been implicated in the pathophysiology of the inflammatory diseases. Recent studies have revealed the important relations between vitamin D and Behçet's disease (BD). Vitamin D function and its deficiency have been linked to a wide range of metabolic disorders including malignant, cardiovascular, infectious, neuromuscular, and autoimmune diseases. Here, we provide a brief analysis of the recent literature regarding immune-regulatory effects as well as clinical evidence of vitamin D influence on the molecular level in BD.

Vitamin D and Spondyloarthritis: Review of the Literature

Background:

Spondyloarthritides (SpAs) encompass heterogeneous diseases sharing similar genetic background, pathogenic mechanisms, and phenotypic features. Vitamin D is essential for calcium metabolism and skeletal homeostasis. Some recent evidences reported supplemental functions of vitamin D, such as modulation of inflammatory reactions.

Objective:

To analyze published data about a possible association between vitamin D and SpAs.

Results:

Vitamin D could play a role in immune reactions, influencing both immune and adaptive response. Vitamin D deficiency is more frequent in SpAs than in general population: an active and more severe disease infers patients’ mobility and reduces sunlight exposure. Quiescent inflammatory bowel disease, frequently associated with SpAs, could worsen vitamin D deficiency. All the parameters related to UVB exposure are the most important determinants for vitamin D status and need to be considered evaluating the vitamin D levels in SpAs.

Apart from musculoskeletal problems, patients affected by SpAs frequently suffer from other comorbidities, especially cardiovascular diseases and osteoporosis, and vitamin D status could have a relevance in this field. Bone is involved in SpAs with a dualistic role, coexisting trabecular bone resorption and new bone formation.

It seems rational to monitor vitamin D levels in SpA subjects and to target it to global health threshold.

Conclusion:

Literature data were not completely in agreement about a possible relation between poor vitamin D status and onset or worse disease course of SpAs. In fact, these results come from cross-sectional studies, which affect our ability to infer causality. Therefore, large, randomized controlled trials are needed.

Vitamin D status of tuberculosis patients with diabetes mellitus in different economic areas and associated factors in China

BACKGROUND

Vitamin D could be a mediator in the association between tuberculosis (TB) and diabetes mellitus (DM). A large scale multi-center study confirmed that TB patients with DM had significantly lower serum vitamin D level compared with those without DM and reported that DM was a strong independent risk factor for vitamin D deficiency.

OBJECTIVES

This study was undertaken to determine amongst patients with both TB and DM living in different economically defined areas in China: i) their baseline characteristics, ii) their vitamin D status and iii) whether certain baseline characteristics were associated with vitamin D deficiency.

METHODS

In DM-TB patients consecutively attending seven clinics or hospitals, we measured 25 hydroxycholecalciferol at the time of registration using electrochemiluminescence in a COBASE 601 Roche analyser by chemiluminescence immunoassay. Data analysis was performed using chi square test and multivariate logistic regression.

RESULTS

There were 178 DM-TB patients that included 50 from economically well-developed areas, 103 from better-off areas and 25 from a poverty area. Median vitamin D levels in well-developed, better-off and poverty areas were 11.5ng/ml, 12.2ng/ml and 11.5ng/ml respectively. Amongst all patients, 149 (84%) had vitamin D deficiency-91 (51%) with vitamin D deficiency (10-19.9 ng/ml) and 58 (33%) with severe deficiency (< 10 ng/ml). There was a significantly higher proportion with vitamin D deficiency in the poverty area. The adjusted odds of vitamin D deficiency (25-(OH)D3 <20 ng/ml) were significantly higher in those with longer history of DM (P = 0.038) and with HbA1c≥10% (P = 0.003).

CONCLUSION

Over 80% of TB patients with DM in China were vitamin D deficient, with risk factors being residence in a poverty area, a long duration of DM and uncontrolled DM. TB programme managers and clinicians need to pay more attention to the vitamin D status of their patients.

Polymorphisms of the vitamin D receptor gene (FOKI, CDX2, and GATA) and susceptibility to chronic periodontitis in diabetic and non-diabetic individuals: A case-control study

AIM

The aim of the present study was to evaluate the distribution of single-nucleotide polymorphisms (SNP) (variants FOKI [rs2228570], CDX2 [rs47908762], and GATA [rs4516035]) in the vitamin D receptor in individuals with type 2 diabetes mellitus and chronic periodontitis (DM2 + CP), CP alone, and healthy individuals, and to investigate the relationship with susceptibility to CP.

METHODS

In total, 280 individuals (116 with DM2 + CP, 95 with CP alone, and 69 healthy individuals) were genotyped using real-time polymerase chain reaction with allele-specific probes. Significant differences (P < .05) were found among the groups with regard to socio-epidemiological variables (sex, marital status, income, smoking habit, and schooling) and clinical-epidemiological variables (age, number of teeth, probing depth, clinical attachment loss, gingival bleeding index, and visible plaque index).

RESULTS

The C allele was significantly more frequent among the healthy individuals (34.8%) than those with DM2 + CP (23.5%) (odds ratio [OR] = .58, 95% confidence interval [CI]: . 35-.94, P = .022). Likewise, the CC allele was significantly more frequent among healthy individuals (11.6%) than those with DM2 + CP (2.6%) (OR = .17, 95% CI: .03-.79, P = .015).

CONCLUSION

The results suggest that the presence of these variants could lead to a lower susceptibility to DM2 and CP. No other significant differences among groups were found for the other SNP investigated.

Neglected tropical diseases and vitamin B12: a review of the current evidence

Vitamin B12 deficiency is an urgent public health problem that disproportionately affects individuals in low- and middle-income settings, where the burden of neglected tropical diseases (NTDs) is also unacceptably high. Emerging evidence supports a potential role of micronutrients in modulating the risk and severity of NTDs. However, the role of vitamin B12 in NTD pathogenesis is unknown. This systematic review was conducted to evaluate the evidence on the role of vitamin B12 in the etiology of NTDs. Ten studies were included in this review: one study using an in vitro/animal model, eight observational human studies and one ancillary analysis conducted within an intervention trial. Most research to date has focused on vitamin B12 status and helminthic infections. One study examined the effects of vitamin B12 interventions in NTDs in animal and in vitro models. Few prospective studies have been conducted to date to examine the role of vitamin B12 in NTDs. The limited literature in this area constrains our ability to make specific recommendations. Larger prospective human studies are needed to elucidate the role of vitamin B12 in NTD risk and severity in order to inform interventions in at-risk populations.

Vitamin D and systemic lupus erythematosus - The hype and the hope

Over the past 20years, much has been written about the potential role of vitamin D in on adverse health outcomes. In recent years, evidence has accumulated regarding the effect of vitamin D on the immune system, and its different cells. Some studies have noted lower vitamin D concentrations in patients with SLE. These epidemiological data still not answer the question: is vitamin D deficiency the cause or the effect? To answer this, we will discuss the association between vitamin D deficiency and SLE and review the evidence from interventional studies.

Vitamin D status in tuberculosis patients with diabetes, prediabetes and normal blood glucose in China: a cross-sectional study

OBJECTIVE

The association between tuberculosis (TB), diabetes mellitus (DM) and vitamin D status is poorly characterised. We therefore: (1) determined vitamin D status in patients with TB in relation to whether they had normal fasting blood glucose (FBG), pre-DM or DM and (2) assessed whether baseline characteristics in patients with TB, including their DM status, were associated with vitamin D deficiency.

METHODS

In patients with TB consecutively attending six clinics or hospitals in China, we measured 25-hydroxycholecalciferol (25-(OH)D₃) at the time of registration using electrochemiluminescence in a COBASE 601 Roche analyser by chemiluminescence immunoassay. Data analysis was performed using the χ² test, ORs and multivariate logistic regression.

RESULTS

There were 306 eligible patients with TB, including 96 with smear positive pulmonary TB, 187 with smear negative pulmonary TB and 23 with extrapulmonary TB. Of these, 95 (31%) had normal blood glucose, 83 (27%) had pre-DM and 128 (42%) had DM. Median serum vitamin D levels were 16.1 ng/mL in patients with TB with normal FBG, 12.6 ng/mL in patients with TB with pre-DM and 12.1 ng/mL in patients with TB with DM (p<0.001). The study highlighted certain baseline characteristics associated with vitamin D deficiency (25-(OH)D₃<20 ng/mL). After adjusting for confounders, serum vitamin D deficiency was significantly more common in patients being registered in the cold season (November to April) (p=0.006) and in those with DM (p=0.003).

CONCLUSION

Vitamin D levels are lower in patients with TB with pre-DM and DM and are also affected by certain baseline characteristics that include being registered in the cold season and having DM. TB programmes need to pay more attention to vitamin D status in their patients, especially if there is coexisting pre-DM or DM.

The relationship of serum vitamins A, D, E and LL-37 levels with allergic status, tonsillar virus detection and immune response

Background

Tonsils have an active role in immune defence and inducing and maintaining tolerance to allergens. Vitamins A, D, and E, and antimicrobial peptide LL-37 may have immunomodulatory effects. We studied how their serum levels were associated with allergy status, intratonsillar/nasopharyngeal virus detection and intratonsillar expression of T cell- and innate immune response-specific cytokines, transcription factors and type I/II/III interferons in patients undergoing tonsillectomy.

Methods

110 elective tonsillectomy patients participated. Serum levels of vitamins A, 25(OH)D, and E, LL-37 and allergen-specific IgE as well as nasopharyngeal/intratonsillar respiratory viruses were analyzed. The mRNA expression of IFN-α, IFN-β, IFN-γ, IL-10, IL-13, IL-17, IL-28, IL-29, IL-37, TGF-β, FOXP3, GATA3, RORC2 and Tbet in tonsils were analyzed by quantitative RT-PCR.

Results

The median age of the patients was 16 years (range 3–60), 28% of subjects had atopy, and 57% carried ≥1 respiratory virus in nasopharynx. Detection of viruses decreased by age. Higher vitamin A levels showed borderline significance with less viral detection (P = 0.056). Higher 25(OH)D was associated with less allergic rhinitis and atopy (P < 0.05) and higher vitamin E with less self-reported allergy (P < 0.05). In gene expression analyses, 25(OH)D was associated with higher IL-37, vitamin A with higher IFN-γ and vitamin E with less IL-28 (P < 0.05). LL-37 was associated with less FOXP3, RORC2 and IL-17 in tonsils (P < 0.05).

Conclusions

Vitamin D and E levels were associated with less allergic disorders. Vitamin A was linked to antiviral and vitamin D with anti-inflammatory activity. LL-37 and was linked to T regulatory cell effects.

Vitamin D deficiency in chronic inflammatory rheumatic diseases: results of the cardiovascular in rheumatology [CARMA] study

INTRODUCTION

The aim was to study the association between 25-hydroxyvitamin D (25(OH)D) levels and the clinical characteristics of patients with chronic inflammatory rheumatic diseases (CIRD).

METHODS

We studied a cross-section from the baseline visit of the CARMA project (CARdiovascular in rheuMAtology), a 10-year prospective study evaluating the risk of cardiovascular events in rheumatoid arthritis (RA), ankylosing spondylitis (AS) and psoriatic arthritis (PsA) patients, and non-CIRD patients who attended rheumatology outpatient clinics from 67 hospitals in Spain. Non-CIRD group was frequency matched by age with the joint distribution of the three CIRD groups included in the study. 25(OH)D deficiency was defined if 25(OH)D vitamin levels were < 20 ng/ml.

RESULTS

2.234 patients (775 RA, 738 AS and 721 PsA) and 677 non-CIRD subjects were assessed. The median (p25-p75) 25(OH)D levels were: 20.4 (14.4-29.2) ng/ml in RA, 20.9 (13.1-29.0) in AS, 20.0 (14.0-28.8) in PsA, and 24.8 (18.4-32.6) ng/ml in non-CIRD patients. We detected 25(OH)D deficiency in 40.5 % RA, 39.7 % AS, 40.9 % PsA and 26.7 % non-CIRD controls (p < 0.001). A statistically significant positive association between RA and 25(OH)D deficiency was found (adjusted (adj.) OR = 1.46; 95 % CI = 1.09-1.96); p = 0.012. This positive association did not reach statistical significance for AS (adj. OR 1.23; 95 % CI = 0.85-1.80) and PsA (adj. OR 1.32; 95 % CI = 0.94-1.84). When the parameters of disease activity, severity or functional impairment were assessed, a marginally significant association between 25(OH)D deficiency and ACPA positivity in RA patients (adj. OR = 1.45; 95 % CI = 0.99-2.12; p = 0.056), and between 25(OH)D deficiency and BASFI in AS patients (adj. OR = 1.08; 95 % CI = 0.99-1.17); p = 0.07) was also found.

CONCLUSIONS

Patients with RA show an increased risk of having 25(OH)D deficiency compared to non-CIRD controls.

Vitamin D insufficiency and insulin resistance in obese adolescents

Obese adolescents represent a particularly vulnerable group for vitamin D deficiency which appears to have negative consequences on insulin resistance and glucose homeostasis. Poor vitamin D status is also associated with future risk of type 2 diabetes and metabolic syndrome in the obese. The biological mechanisms by which vitamin D influences glycemic control in obesity are not well understood, but are thought to involve enhancement of peripheral/hepatic uptake of glucose, attenuation of inflammation and/or regulation of insulin synthesis/secretion by pancreatic β cells. Related to the latter, recent data suggest that the active form of vitamin, 1,25-dihydroxyvitamin D, does not impact insulin release in healthy pancreatic islets; instead they require an environmental stressor such as inflammation or vitamin D deficiency to see an effect. To date, a number of observational studies exploring the relationship between the vitamin D status of obese adolescents and markers of glucose homeostasis have been published. Most, although not all, show significant associations between circulating 25-hydroxyvitamn D concentrations and insulin sensitivity/resistance indices. In interpreting the collective findings of these reports, significant considerations surface including the effects of pubertal status, vitamin D status, influence of parathyroid hormone status and the presence of nonalcoholic fatty liver disease. The few published clinical trials using vitamin D supplementation to improve insulin resistance and impaired glucose tolerance in obese adolescents have yielded beneficial effects. However, there is a need for more randomized controlled trials. Future investigations should involve larger sample sizes of obese adolescents with documented vitamin D deficiency, and careful selection of the dose, dosing regimen and achievement of target 25-hydroxyvitamn D serum concentrations. These trials should also include clamp-derived measures of in vivo sensitivity and β-cell function to more fully characterize the effects of vitamin D replenishment on insulin resistance.

Relationship between the effect of eldecalcitol and serum 25(OH)D level

In previous studies, we demonstrated that 12-month treatment with 0.75μg/day eldecalcitol increased bone mineral density in osteoporotic patients regardless of serum 25-hydroxyvitamin D (25(OH)D) level, and in a 3-year randomized double-blind clinical trial, eldecalcitol significantly reduced the incidences of vertebral and wrist fractures compared to alfacalcidol. However, it remains unclear whether the fracture risk reduction by eldecalcitol is affected by serum 25(OH)D. In the fracture prevention trial, patients with low 25(OH)D level at baseline were supplemented with 400IU/day native vitamin D3. In the current study, patients from that trial were divided according to the tertiles of serum 25(OH)D level at 6 months after treatment initiation. The increases in lumbar and hip BMD by eldecalcitol were significantly higher in all tertiles than those by alfacalcidol. The incidences of vertebral and osteoporotic fractures tended to be lower in each tertile of the eldecalcitol-treated group than in the corresponding tertile of the alfacalcidol-treated group, with the exception of vertebral fractures in the low tertile. We also investigated whether eldecalcitol treatment affected levels of serum 25(OH)D, serum 1,25(OH)2D, and parathyroid hormone in patients without vitamin D supplementation. With eldecalcitol treatment, serum 1,25(OH)2D concentration was reduced by approximately 50%, whereas serum levels of parathyroid hormone and 25(OH)D were not affected. The major findings of the present study were that eldecalcitol did not affect serum 25(OH)D levels, and that it reduced the incidence of osteoporotic fractures and increased BMD in comparison with alfacalcidol regardless of serum 25(OH)D level within the range of serum 25(OH)D concentrations at or higher than 20ng/mL. Whether eldecalcitol is similarly effective at vitamin D deficient serum 25(OH)D levels remains to be clarified. This article is part of a Special Issue entitled 'Vitamin D Workshop'.

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.

Vitamin D in ankylosing spondylitis: review and meta-analysis

BACKGROUND

The role of vitamin D in ankylosing spondylitis (AS) is largely unknown. This paper aims to examine the association between serum vitamin D levels and susceptibility and disease activity of AS.

METHODS

We searched the relevant literatures in PubMed, Elsevier Science Direct, Chinese Biomedical Database (CBM), Chinese National Knowledge Infrastructure (CNKI) and Wanfang (Chinese) Database published before June 2014. Eight independent case-control studies with a total of 533 AS patients and 478 matching controls were selected into this meta-analysis. Standard mean differences (SMDs) with 95% confidence intervals (CIs) were used to assess the levels of serum vitamin D, parathyroid hormone (PTH), serum calcium and alkaline phosphatase (ALP) in cases and controls, respectively. Correlation coefficients (CORs) have been performed to value the correlationship between vitamin D and disease activity (erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) and Bath Ankylosing Spondylitis Disease Activity Index (BASDAI)) of AS patients.

RESULTS

Meta-analysis results suggested that vitamin D may play a protective role in AS (for total vitamin D: SMD=-0.71, P<0.001; for 25OHD: SMD=-0.66, P=0.002; for 1,25OHD: SMD=-0.72, P=0.19). Differences in PTH and serum calcium levels were not significant in AS (SMD=-0.10, P=0.67; SMD=0.12, P=0.17 respectively), while ALP was associated with AS susceptibility (SMD=0.20, P=0.04). The relationship between serum vitamin D levels and disease activity was statistically significant except for 25OHD versus (vs.) CRP or BASDAI (for CRP vs. 25OHD: COR=-0.22, P=0.08; for BASDAI vs. 25OHD: COR=-0.20, P=0.06, respectively).

CONCLUSION

The higher levels of serum vitamin D were associated with a decreased risk of AS, and showed an inverse relationship with AS activity.

[Vitamin D levels in ankylosing spondylitis: does deficiency correspond to disease activity?]

Ankylosing spondylitis (AS) is an inflammatory disorder that presents with arthritis of the axial skeleton, including sacroiliac joints. Vitamin D is a secosteroid hormone with a long-established role in calcium and phosphate homeostasis, and in the regulation of bone formation and resorption. It is now known that vitamin D plays an immunosuppressive role in the body, and there is interest of late in the role of vitamin D in autoimmune diseases. Inflammation may be responsible for some of the loss of bone mineral density seen in AS. We reviewed the literature for studies assessing vitamin D level as a marker of AS disease activity and those examining vitamin D levels in AS in comparison to healthy controls. Four of 7 studies found a significant negative correlation between vitamin D levels and Bath Ankylosing Spondylitis Index (BASDAI), erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). In a review of 8 case-control studies, the mean level of 25-hydroxyvitamin D3 was 22.8 ± 14.1 ng/mL in 555 AS patients versus 26.6 ± 12.5 ng/mL in 557 healthy controls. When compared with a 2-sample t test, vitamin D levels were significantly higher in healthy controls (p < 0.01). We conclude that patients with AS appear to have lower vitamin D levels versus healthy controls; however, the cause is unclear. Existing studies do not demonstrate a consistent link between vitamin D levels and disease activity in AS. Further studies are in need to determine if a causative link exists between vitamin D deficiency and AS.

Vitamin D receptor TaqI and ApaI polymorphisms: a comparative study in patients with Behçet's disease and Rheumatoid arthritis in Tunisian population

Recent genetic surveys have identified vitamin D receptor (VDR) as a susceptibility gene for several autoimmune diseases. This study was designed to investigate the association of VDR gene polymorphisms with Behçet's disease (BD) and Rheumatoid arthritis (RA). A case-control study including 151 BD, 106 RA patients and an appropriate number of healthy control subjects were performed using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) techniques. Association between TaqI polymorphism and BD was marginal under codominant and recessive models (P=0.078 and P=0.058, respectively). After stratification, we found evidence for a significant association between TaqI polymorphism and BD in the elderly subjects (P=0.037). The minor ApaI a allele tended to confer an increased risk for BD susceptibility (P=0.087). BD patients with VDR homozygous AA or aa genotypes were at increased risk for development of erythema nodosum (EN) skin manifestation (P=0.038). No significant association was observed for VDR ApaI and TaqI polymorphisms with RA risk (P>0.05). TaqI and ApaI polymorphisms might be modestly implicated in BD pathogenesis. They could be considered as potential biomarkers in BD rather than susceptibility genes. However, TaqI and ApaI seemed not to be implicated in RA pathogenesis.

Vitamin D deficiency and risk for rheumatic diseases: an update

PURPOSE OF REVIEW

The role of vitamin D in situations other than calcium homeostasis and bone health has become very topical. It is apparent that vitamin D has significant effects on the immune system and as such may contribute to the pathogenesis of autoimmune disease. This review examines the evidence-to-date that vitamin D has a role in immune-mediated rheumatic disorders.

RECENT FINDINGS

Low vitamin D status is reported in many inflammatory rheumatic conditions. In some this extends to an association with disease activity. Vitamin D acts on a number of cells involved in both innate and acquired immunity biasing the adaptive immune system away from Th17 and Th1, towards Th2 and Tregs. Deficiency accordingly could encourage autoimmunity. Direct evidence for this plausible mechanism in specific diseases remains largely to be demonstrated. To date, there is a dearth of controlled trials of vitamin D in prophylaxis or therapy.

SUMMARY

Vitamin D deficiency may well be an important factor in autoimmune rheumatic disease, including initial disease development and worsening the disease once present. This is testable and there is a pressing need for therapeutic studies.

Vitamin D status in patients with rosacea

BACKGROUND

Rosacea is a common chronic skin condition affecting the face. In recent years, significant evidence shows that vitamin D plays an important role in modulating the immune system. Vitamin D and its analogues via these mechanisms are playing an increasing role in the management of atopic dermatitis, psoriasis, vitiligo, acne and rosacea.

OBJECTIVES

In our study, we aimed to investigate the relationship between serum vitamin D levels in patients with rosacea and analyze the association of vitamin D with clinical features.

METHODS

Forty-four rosacea patients and 32 healthy control subjects were included into the study. 25-hydroxyvitamin D (25(OH)D), calcium and intact parathyroid hormone were measured. Deficiency of vitamin D is defined as the level of 25(OH)D being less than 20 ng/ml.

RESULTS

Thirty-three female and 11 male patients were included in the study. The mean age of patients was 48.6 ± 11.5. The mean levels of vitamin D levels were found as 21.4 ± 9.9 and 17.1 ± 7.9 in patients and controls, respectively. The difference was statistically significant (p = 0.04). The prevalence of vitamin D deficiency in patients with rosacea was 38.6% and 28.1% in healthy controls (p = 0.34).

CONCLUSIONS

To the best of our knowledge, our study is the first study for evaluating serum vitamin D levels of patients with rosacea in the literature. Patients with rosacea have relatively high serum vitamin D levels compared to control groups. The result of our study suggests that increased vitamin D levels may lead to the development of rosacea. To confirm status of vitamin D levels in patients with rosacea, larger epidemiological studies are needed.

Vitamin d, the cutaneous barrier, antimicrobial peptides and allergies: is there a link?

Atopic diseases such as atopic dermatitis (AD) are very common in industrialized countries. Up to 15%-30% of all children and 2%-10% of all adults suffer from AD. Already in early disease stages, a defective epidermal barrier is known to contribute to the pathogenesis of AD. Central elements in the epidermal barrier are antimicrobial peptides (AMPs), which are secreted by keratinocytes, sweat gland cells but also infiltrating immune cells. AMPs function as endogenous antibiotics and are able to kill bacteria, viruses, and fungi. Furthermore AMPs act as immune modulators with effects on the innate and adaptive immune system. The probably best studied AMPs in human skin are the defensins and cathelicidin. In atopic diseases the functions of AMPs such as cathelicidin might be impaired and microbial superinfections could serve as cofactors for allergic sensitization. Hence, induction of AMPs could be beneficial in these patients. Cathelicidin which is often referred to its peptide form hCAP18 or LL-37 can be induced by ultraviolet light B (UVB) irradiation and is upregulated in infected and injured skin. The cathelicidin gene carries a vitamin D response element and the vitamin D pathway could therefore be targeted for cathelicidin regulation. As the development and course of atopic diseases might be influenced by vitamin D signaling these pathomechanisms could explain the growing evidence connecting vitamin D to allergic diseases, including AD, allergic rhinitis, food allergies and asthma. In this review the role of vitamin D and the AMP cathelicidin in the pathogenesis of atopic diseases with impaired barrier function will be discussed.

[Hungarian consensus regarding the role of vitamin D in the prevention and treatment of diseases]

The metabolism of vitamin D is unique in the human body and its diverse effects are present in almost every organ. Vitamin D deficiency is one of the most prominent health issues in the civilized world. For the solution of this concern an extensive collaboration is imperative. Recognizing this necessity the most prominent Hungarian medical associations fighting with the effects of vitamin D deficiency worked out a collective consensus on the importance, diagnosis, prevention and suggested therapy of vitamin D deficiency. Along with the clinical guidelines of the different associations, the result of this consensus could serve as guidance for the practicing doctors in the prevention and therapy of vitamin D deficiency. In addition the consensus aims to direct the attention of decision-makers and the general public on the significance of this issue.

Effects of Solanum glaucophyllum toxicity on cell proliferation and apoptosis in the small and large intestine of rabbits

Vitamin D regulates mineral homeostases and enterocyte proliferation and differentiation. Hypervitaminosis D generates changes in cell proliferation, differentiation and apoptosis in several organs. We analysed morphometric parameters and proliferative and apoptotic indices in the intestinal epithelium of rabbits with hypervitaminosis D induced by the chronic treatment with the calcinogenic plant Solanum glaucophyllum. Rabbits were treated for 15 or 30 days. A group was treated for 15 days and led to possible recovery for 30 days. Another group was nutritionally restricted for 30 days. Morphological, morphometric, proliferative and apoptotic changes were found in the treated animals. Mild atrophy and reduced proliferation was found in the jejunum and ileum. Apoptosis increased in the crypts of the ileum and in the superficial epithelium and crypts of the rectum. Most of the alterations were partially recovered. The possible involvement in these changes of the hypervitaminosis D-like state induced by S. glaucophyllum is discussed.

Eldecalcitol: a review of its use in the treatment of osteoporosis

Eldecalcitol (1α,25[OH](2)-2β-(3-hydroxypropyloxy)vitamin D(3); ED-71; Edirol®) is an orally administered analogue of active vitamin D (calcitriol) that is available in Japan for the treatment of osteoporosis. Two randomized, double-blind, multicentre trials were conducted in patients with osteoporosis. In a placebo-controlled, dose-ranging trial, eldecalcitol significantly reduced serum bone-specific alkaline phosphatase (BALP) and serum osteocalcin, markers of bone formation, more than placebo. Eldecalcitol at a 1.0 μg/day dosage, but not at lower dosages, also significantly reduced urinary type I collagen N-telopeptide (NTX), a marker of bone resorption, more than placebo. In a comparison with alfacalcidol (a prodrug of calcitriol), eldecalcitol produced significantly greater reductions in serum BALP and urinary NTX, and had a positive effect on CT markers of femoral biomechanical properties. In the comparison with alfacalcidol, eldecalcitol 0.75 μg/day significantly reduced the 3-year incidence of vertebral fractures, with an absolute risk reduction of 4.1% over this period, representing a relative risk reduction of 26%. There was no significant difference in the rate of non-vertebral fractures. In both trials, eldecalcitol treatment was also associated with an increase in bone mineral density, whereas patients who received the comparators generally had a reduction in bone mineral density. Increases in blood calcium (to >2.6 mmol/L) and urinary calcium (to >0.1 mmol/L glomerular filtrate) were the most clinically important treatment-emergent adverse events. In the placebo-controlled, dose-ranging trial, 23% and 25% of patients in the eldecalcitol 1 μg/day group had increased blood and urinary calcium compared with 7% and 7%, 6% [corrected] and 9%, and 0% and 1.9% in the eldecalcitol 0.5 and 0.75 μg/day, and placebo groups, respectively. In the comparison with alfacalcidol, 21.0% and 13.5% of eldecalcitol 0.75 μg/day and alfacalcidol 1.0 μg/day recipients had increased blood calcium, whereas hypercalcaemia (defined as a serum calcium >2.9 mmol/L) occurred in 0.4% and urolithiasis in 1.3% of eldecalcitol recipients over 36 months of treatment. Eldecalcitol is an efficacious treatment for patients with osteoporosis that should be further investigated in head-to-head trials with other recommended first-line pharmacological treatments.

Impact of vitamin D3 on cutaneous immunity and antimicrobial peptide expression

Antimicrobial peptides (AMPs) are effectors of cutaneous innate immunity and protect primarily against microbial infections. An array of AMPs can be found in and on the skin. Those include peptides that were first discovered for their antimicrobial properties but also proteins with antimicrobial activity first characterized for their activity as chemokines, enzymes, enzyme inhibitors and neuropeptides. Cathelicidins were among the first families of AMPs discovered in skin. They are now known to exert a dual role in innate immune defense: they have direct antimicrobial activity and will also initiate a host cellular response resulting in cytokine release, inflammation and angiogenesis. Altered cathelicidin expression and function was observed in several common inflammatory skin diseases such as atopic dermatitis, rosacea and psoriasis. Until recently the molecular mechanisms underlying cathelicidin regulation were not known. Lately, vitamin D3 was identified as the major regulator of cathelicidin expression and entered the spotlight as an immune modulator with impact on both, innate and adaptive immunity. Therapies targeting vitamin D3 signalling may provide novel approaches for the treatment of infectious and inflammatory skin diseases by affecting both innate and adaptive immune functions through AMP regulation.

Vitamin D deficiency & cardiovascular disease

Evolving data indicate that vitamin D deficiency is associated with an increased risk of cardiovascular disease (CVD). The purpose of this article is to increase NPs' awareness of the link between vitamin D deficiency and CVD, and to assist with recommendations for screening and treatment in at-risk patients.

Products of vitamin D3 or 7-dehydrocholesterol metabolism by cytochrome P450scc show anti-leukemia effects, having low or absent calcemic activity

Background

Cytochrome P450scc metabolizes vitamin D3 to 20-hydroxyvitamin D3 (20(OH)D3) and 20,23(OH)₂D3, as well as 1-hydroxyvitamin D3 to 1α,20-dihydroxyvitamin D3 (1,20(OH)₂D3). It also cleaves the side chain of 7-dehydrocholesterol producing 7-dehydropregnenolone (7DHP), which can be transformed to 20(OH)7DHP. UVB induces transformation of the steroidal 5,7-dienes to pregnacalciferol (pD) and a lumisterol-like compounds (pL).

Methods and Findings

To define the biological significance of these P450scc-initiated pathways, we tested the effects of their 5,7-diene precursors and secosteroidal products on leukemia cell differentiation and proliferation in comparison to 1α,25-dihydroxyvitamin D3 (1,25(OH)₂D3). These secosteroids inhibited proliferation and induced erythroid differentiation of K562 human chronic myeloid and MEL mouse leukemia cells with 20(OH)D3 and 20,23(OH)₂D3 being either equipotent or slightly less potent than 1,25(OH)₂D3, while 1,20(OH)₂D3, pD and pL compounds were slightly or moderately less potent. The compounds also inhibited proliferation and induced monocytic differentiation of HL-60 promyelocytic and U937 promonocytic human leukemia cells. Among them 1,25(OH)₂D3 was the most potent, 20(OH)D3, 20,23(OH)₂D3 and 1,20(OH)₂D3 were less active, and pD and pL compounds were the least potent. Since it had been previously proven that secosteroids without the side chain (pD) have no effect on systemic calcium levels we performed additional testing in rats and found that 20(OH)D3 had no calcemic activity at concentration as high as 1 µg/kg, whereas, 1,20(OH)₂D3 was slightly to moderately calcemic and 1,25(OH)₂D3 had strong calcemic activity.

Conclusions

We identified novel secosteroids that are excellent candidates for anti-leukemia therapy with 20(OH)D3 deserving special attention because of its relatively high potency and lack of calcemic activity.

Control of cutaneous antimicrobial peptides by vitamin D3

Constant exposure to a wide variety of microbial pathogens represents a major challenge for our skin. Antimicrobial peptides (AMPs) are mediators of cutaneous innate immunity and protect primarily against microbial infections. Cathelicidins were among the first AMPs identified in human skin and recent evidence suggests that they exert a dual role in innate immune defense: At first, due to their antimicrobial activity they kill pathogens directly. In addition, these peptides initiate a potent host response to infection resulting in cytokine release, inflammation and a cellular response. Disturbed cathelicidin expression and function was observed in several common inflammatory skin diseases, such as psoriasis where cathelicidin peptide converts inert self-DNA and self-RNA into an autoimmune stimulus. In atopic dermatitis decreased levels of cathelicidin facilitating microbial superinfections have been discussed. Furthermore, abnormally processed cathelicidin peptides induce inflammation and a vascular response in rosacea. Until recently, the molecular mechanisms underlying cathelicidin regulation were unknown. Recently, the vitamin D3 pathway was identified as the major regulator of cathelicidin expression. Consequently, vitamin D3 entered the spotlight as an immune modulator with impact on both innate and adaptive immunity. Therapies targeting vitamin D3 signaling may provide new approaches for infectious and inflammatory skin diseases by affecting both innate and adaptive immune functions.

A new steroidal 5,7-diene derivative, 3beta-hydroxyandrosta-5,7-diene-17beta-carboxylic acid, shows potent anti-proliferative activity

The new steroidal 5,7-diene, 3beta-hydroxyandrosta-5,7-diene-17beta-carboxylic acid (17-COOH-7DA), was synthesized from 21-acetoxypregnenolone, with the oxidative cleavage of the side chain being dependent on the presence of oxygen. In human epidermal (HaCaT) keratinocytes, 17-COOH-7DA inhibited proliferation in a dose-dependent manner, starting at a dose as low as 10(-11) M. This inhibition was accompanied by decreased expression of epidermal growth factor receptor, bcl2 and cyclin E2 mRNAs and by increased expression of involucrin mRNA. Inhibition of proliferation was associated with slowing of the cell cycle in G1/G0 phases but not with cell death. 17-COOH-7DA was significantly more potent than pregnenolone, 17-COOH-pregnenolone, 17-COOCH(3)-7DA and calcitriol. 17-COOH-7DA also inhibited proliferation of normal human epidermal melanocytes and human and hamster melanoma lines, however, with lower potency than for keratinocytes. In normal human dermal fibroblasts 17-COOH-7DA stimulated proliferation in serum-free media but inhibited it in the presence of 5% serum. 17-COOH-7DA inhibited cell colony formation of human and hamster melanoma cells, and induced monocyte-like differentiation of human HL60 leukemia cells. Thus, the new steroidal 5,7-diene, 17-COOH-7DA, can serve as an inhibitor of proliferation of normal keratinocytes and normal and malignant melanocytes, as a condition-dependent regulator of fibroblast proliferation and a stimulator of leukemia cell differentiation.

1,25-dihydroxyvitamin D3 modulates Th17 polarization and interleukin-22 expression by memory T cells from patients with early rheumatoid arthritis

OBJECTIVE

To examine the immunologic mechanism by which 1,25-dihydroxyvitamin D(3) (1,25[OH](2)D(3)) may prevent corticosteroid-induced osteoporosis in patients with early rheumatoid arthritis (RA), with a focus on T cell biology.

METHODS

Peripheral blood mononuclear cells (PBMCs) and CD4+CD45RO+ (memory) and CD4+CD45RO- (non-memory) T cells separated by fluorescence-activated cell sorting (FACS) from treatment-naive patients with early RA were stimulated with anti-CD3/anti-CD28 in the absence or presence of various concentrations of 1,25(OH)(2)D(3), dexamethasone (DEX), and 1,25(OH)(2)D(3) and DEX combined. Levels of T cell cytokines were determined by enzyme-linked immunosorbent assay and flow cytometry.

RESULTS

The presence of 1,25(OH)(2)D(3) reduced interleukin-17A (IL-17A) and interferon-gamma levels and increased IL-4 levels in stimulated PBMCs from treatment-naive patients with early RA. In addition, 1,25(OH)(2)D(3) had favorable effects on tumor necrosis factor alpha (TNFalpha):IL-4 and IL-17A:IL-4 ratios and prevented the unfavorable effects of DEX on these ratios. Enhanced percentages of IL-17A- and IL-22-expressing CD4+ T cells and IL-17A-expressing memory T cells were observed in PBMCs from treatment-naive patients with early RA as compared with healthy controls. Of note, we found no difference in the percentage of CD45RO+ and CD45RO- cells between these 2 groups. Interestingly, 1,25(OH)(2)D(3), in contrast to DEX, directly modulated human Th17 polarization, accompanied by suppression of IL-17A, IL-17F, TNFalpha, and IL-22 production by memory T cells sorted by FACS from patients with early RA.

CONCLUSION

These data indicate that 1,25(OH)(2)D(3) may contribute its bone-sparing effects in RA patients taking corticosteroids by the modulation of Th17 polarization, inhibition of Th17 cytokines, and stimulation of IL-4.

20-Hydroxycholecalciferol, product of vitamin D3 hydroxylation by P450scc, decreases NF-kappaB activity by increasing IkappaB alpha levels in human keratinocytes

The side chain of vitamin D3 is hydroxylated in a sequential manner by cytochrome P450scc (CYP11A1) to form 20-hydroxycholecalciferol, which can induce growth arrest and differentiation of both primary and immortalized epidermal keratinocytes. Since nuclear factor-κB (NF-κB) plays a pivotal role in the regulation of cell proliferation, differentiation and apoptosis, we examined the capability of 20-hydroxycholecalciferol to modulate the activity of NF-κB, using 1,25-dihydroxycholecalciferol (calcitriol) as a positive control. 20-hydroxycholecalciferol inhibits the activation of NFκB DNA binding activity as well as NF-κB-driven reporter gene activity in keratinocytes. Also, 20-hydroxycholecalciferol induced significant increases in the mRNA and protein levels of the NF-κB inhibitor protein, IκBα, in a time dependent manner, while no changes in total NF-κB-p65 mRNA or protein levels were observed. Another measure of NF-κB activity, p65 translocation from the cytoplasm into the nucleus was also inhibited in extracts of 20-hydroxycholecalciferol treated keratinocytes. Increased IκBα was concomitantly observed in cytosolic extracts of 20-hydroxycholecalciferol treated keratinocytes, as determined by immunoblotting and immunofluorescent staining. In keratinocytes lacking vitamin D receptor (VDR), 20-hydroxycholecalciferol did not affect IκBα mRNA levels, indicating that it requires VDR for its action on NF-κB activity. Comparison of the effects of calcitrol, hormonally active form of vitamin D3, with 20-hydrocholecalciferol show that both agents have a similar potency in inhibiting NF-κB. Since NF-κB is a major transcription factor for the induction of inflammatory mediators, our findings indicate that 20-hydroxycholecalciferol may be an effective therapeutic agent for inflammatory and hyperproliferative skin diseases.

Ageing and vitamin D deficiency: effects on calcium homeostasis and considerations for vitamin D supplementation

Vitamin D is a fat-soluble, seco-steroid hormone. In man, the vitamin D receptor is expressed in almost all tissues, enabling effects in multiple systems of the human body. These effects can be endocrine, paracrine and autocrine. The present review summarises the effects of ageing on the vitamin D endocrine system and on Ca homeostasis. Furthermore, consequences for vitamin D supplementation are discussed.

Calcimimetics or vitamin D analogs for suppressing parathyroid hormone in end-stage renal disease: time for a paradigm shift?

Considerable advances have been made in the understanding of the pathogenesis and treatment of secondary hyperparathyroidism (SHPT) in chronic kidney disease (CKD). These include the discovery that the calcium-sensing receptor has an important role in the regulation of parathyroid gland function, the development of calcimimetics to target this receptor, the recognition that vitamin D receptor activation has important functions beyond the regulation of mineral metabolism, the identification of the phosphaturic factor fibroblast growth factor 23 and the contribution of this hormone to disordered phosphate and vitamin D metabolism in CKD. However, despite the availability of calcimimetics, phosphate binders, and vitamin D analogs, control of SHPT remains suboptimal in many patients with advanced kidney disease. In this Review, we explore several unresolved issues regarding the pathogenesis and treatment of SHPT. Specifically, we examine the significance of elevated circulating fibroblast growth factor 23 levels in CKD, question the proposition that calcitriol deficiency is truly a pathological state, explore the relative importance of the vitamin D receptor and the calcium-sensing receptor in parathyroid gland function and evaluate the evidence to support the treatment of SHPT with calcimimetics and vitamin D analogs. Finally, we propose a novel treatment framework in which calcimimetics are the primary therapy for suppressing parathyroid hormone production in patients with end-stage renal disease.

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.

The vitamin D pathway: a new target for control of the skin's immune response?

The surface of our skin is constantly challenged by a wide variety of microbial pathogens, still cutaneous infections are relatively rare. Within cutaneous innate immunity the production of antimicrobial peptides (AMPs) is a primary system for protection against infection. Many AMPs can be found on the skin, and these include molecules that were discovered for their antimicrobial properties, and other peptides and proteins first known for activity as chemokines, enzymes, enzyme inhibitors and neuropeptides. Cathelicidins were among the first families of AMPs discovered on the skin. They are now known to have two distinct functions; they have direct antimicrobial activity and will initiate a host cellular response resulting in cytokine release, inflammation and angiogenesis. Dysfunction of cathelicidin is relevant in the pathogenesis of several cutaneous diseases including atopic dermatitis where cathelicidin induction is suppressed, rosacea, where cathelicidin peptides are abnormally processed to forms that induce cutaneous inflammation and a vascular response, and psoriasis, where a cathelicidin peptide can convert self-DNA to a potent stimulus of an autoinflammatory cascade. Recent work has unexpectedly identified vitamin D3 as a major factor involved in the regulation of cathelicidin expression. Therapies targeting the vitamin D3 pathway and thereby cathelicidin may provide new treatment modalities in the management of infectious and inflammatory skin diseases.

The complex role of vitamin D in autoimmune diseases

Vitamin D, besides having well-known control functions of calcium and phosphorus metabolism, bone formation and mineralization, also has a role in the maintenance of immune-homeostasis. The immune-regulatory role of vitamin D affects both the innate and adaptive immune system contributing to the immune-tolerance of self-structures. Impaired vitamin D supply/regulation, amongst other factors, leads to the development of autoimmune processes in animal models of various autoimmune diseases. The administration of vitamin D in these animals leads to improvement of immune-mediated symptoms. Moreover, in human autoimmune diseases, such as multiple sclerosis, or rheumatoid arthritis the pathogenic role of vitamin D has been described. The review aims at describing the complex immune-regulatory role of vitamin D from the cellular level through autoimmune animal models and depicting the known contribution of vitamin D in the pathogenesis of human autoimmune diseases.

Antimicrobial peptides and the skin immune defense system

Our skin is constantly challenged by microbes but is rarely infected. Cutaneous production of antimicrobial peptides (AMPs) is a primary system for protection, and expression of some AMPs further increases in response to microbial invasion. Cathelicidins are unique AMPs that protect the skin through 2 distinct pathways: (1) direct antimicrobial activity and (2) initiation of a host response resulting in cytokine release, inflammation, angiogenesis, and reepithelialization. Cathelicidin dysfunction emerges as a central factor in the pathogenesis of several cutaneous diseases, including atopic dermatitis, in which cathelicidin is suppressed; rosacea, in which cathelicidin peptides are abnormally processed to forms that induce inflammation; and psoriasis, in which cathelicidin peptide converts self-DNA to a potent stimulus in an autoinflammatory cascade. Recent work identified vitamin D3 as a major factor involved in the regulation of cathelicidin. Therapies targeting control of cathelicidin and other AMPs might provide new approaches in the management of infectious and inflammatory skin diseases.