Vitamin D and molecular actions on the immune system: modulation of innate and autoimmunity

Assessment of vitamin D status – a changing landscape

In recent years it has been shown that vitamin D deficiency is associated with an increased incidence as well as the progression of a broad range of diseases including osteoporosis, rickets, cardiovascular disease, autoimmune disease, multiple sclerosis and cancer. Consequently, requests for the assessment of vitamin D status have increased dramatically. Despite significant progress in the analysis of vitamin D metabolites and an expansion of our pathophysiological knowledge of vitamin D, the assessment of vitamin D status remains a challenging and partially unresolved issue. Current guidelines from scientific bodies recommend the measurement of 25-hydroxy vitamin D (25-OHD) in blood as the preferred test. However, growing evidence indicates significant limitations of this test, including analytical aspects and interpretation of results. In addition, the relationships between 25-OHD and various clinical indices, such as bone mineral density and fracture risk, are rather weak and not consistent across races. Recent studies have systematically investigated new markers of vitamin D status including the vitamin D metabolite ratio (VMR) (ratio between 25-OHD and 24,25-dihydroxy vitamin D), bioavailable 25-OHD [25-OHD not bound to vitamin D binding protein (DBP)], and free 25-OHD [circulating 25-OHD bound to neither DBP nor albumin (ALB)]. These parameters may potentially change how we will assess vitamin D status in the future. Although these new biomarkers have expanded our knowledge about vitamin D metabolism, a range of unresolved issues regarding their measurement and the interpretation of results prevent their use in daily practice. It can be expected that some of these issues will be overcome in the near future so that they may be considered for routine use (at least in specialized centers). In addition, genetic studies have revealed several polymorphisms in key proteins of vitamin D metabolism that affect the circulating concentrations of vitamin D metabolites. The affected proteins include DBP, 7-dehydrocholesterol synthase and the vitamin D receptor (VDR). Here we aim to review existing knowledge regarding the biochemistry, physiology and measurement of vitamin D. We will also provide an overview of current and emerging biomarkers for the assessment of vitamin D status, with particular attention methodological aspects and their usefulness in clinical practice.

Vitamin D and cardiovascular disease: From atherosclerosis to myocardial infarction and stroke

There continues to be interest in understanding the role of vitamin D in the pathogenesis, epidemiology and prevention of cardiovascular disease (CVD). In fact vitamin D deficiency has been associated to an increased risk of developing CVD given to the relationship between low vitamin D levels and obesity, diabetes mellitus, dyslipidaemia, endothelial dysfunction and hypertension. However, although vitamin D has been identified as a potentially important marker of CVD, the mechanisms through which vitamin D deficiency leads from endothelial dysfunction to myocardial infarction and stroke are not fully understood. Thus, the goal of this review is to provide an updated review of the literature on the basic science of how vitamin D may affect the cardiovascular system and in particular to analyze the role that vitamin D may have in the whole dynamic process from the initiation of endothelial dysfunction to the development of myocardial infarction and stroke.

Role of Vitamin D in the Hygiene Hypothesis: The Interplay between Vitamin D, Vitamin D Receptors, Gut Microbiota, and Immune Response

The hygiene hypothesis postulates that higher levels of cleanliness and improper exposure to microorganisms early in childhood could disturb the intestinal microbiome resulting in abnormal immune responses. Recently, more attention has been put on how a lack of sun exposure and consequently vitamin D deficiency could lead to less immune tolerance and aberrant immune responses. Moreover, vitamin D receptor (VDR) function has been positioned to be a critical aspect of immune response and gut homeostasis. Therefore, this review focuses on the role that the interaction between vitamin D, VDR function, and gut microbiome might have on autoimmune diseases in the context of the hygiene hypothesis. Literature shows that there is a high correlation between vitamin D deficiency, VDR dysfunction, gut microbiota composition, and autoimmune diseases. The biologically active form of vitamin D, 1,25(OH)₂D₃, serves as the primary ligand for VDRs, which have been shown to play a fundamental role in reducing autoimmune disease symptoms. Although the biological functions of VDR, the effects of its genetic variants, and the effects of epigenetic profiles in its promoter region are largely unknown in humans, studies in murine models are increasingly demonstrating that VDRs play a crucial role in attenuating autoimmune disease symptoms by regulating autophagy and the production of antimicrobial peptides, such cathelicidin and β-defensin, which are responsible for modifying the intestinal microbiota to a healthier composition. Remarkably, evidence shows that hormonal compounds and byproducts of the microbiota such as secondary bile acids might also activate VDR. Therefore, understanding the interaction between VDR and gut microbiota is of the utmost importance toward understanding the rise in autoimmune diseases in Western countries. We have gained insights on how the VDR functions affects inflammation, autophagy, and microbiota composition that could lead to the development of pathogenesis of autoimmune diseases, while confirming the role vitamin D and VDRs have in the context of hygiene hypothesis.

The relationship between serum vitamin D and chronic rhinosinusitis: A systematic review

BACKGROUND

An exciting development in upper respiratory tract disease is the pathophysiology of vitamin D (VD3). There now is substantial literature to indicate that VD3 acts as an immunomodulator of adaptive and innate immunity locally within the respiratory epithelium. Chronic rhinosinusitis (CRS) places a relatively large socioeconomic burden on developed nations, yet remains a difficult disease to treat. VD3, therefore, has become an area of clinical interest because it may provide an adjunctive drug therapy option in CRS, thereby potentially improving the quality of life of these patients.

OBJECTIVE

A systematic review of the relationship among serum VD3 levels, CRS phenotype, and disease severity by using outcome assessments.

METHODS

A systematic search was performed by using the PubMed, MEDLINE, and EMBASE databases. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed. Studies that measured serum VD3 levels and correlated the measurements to any subtype of CRS (with or without nasal polyps) were included for qualitative analysis.

RESULTS

Seven articles were included (four prospective and three retrospective studies), with a total of 539 patients. There were significantly lower VD3 levels in the polypoid phenotypes of CRS compared with controls. Low VD3 levels were often associated with an increased degree of inflammation.

CONCLUSION

The available evidence indicated that there is a significant relationship between low VD3 levels and polypoid CRS phenotypes. The association between VD3 levels and disease severity and VD3 potential for drug therapy remains unclear, which warrants further research in the area.

Vitamin D and bone loss in HIV

PURPOSE OF REVIEW

Bone health has become an increasingly important aspect of the care of HIV-infected patients as bone loss with antiretroviral therapy (ART) initiation is significant and osteopenia and osteoporosis are highly prevalent. Vitamin D is tightly linked to calcium balance and bone health, and vitamin D deficiency is common in HIV. This review outlines the epidemiology of vitamin D deficiency in HIV, summarizes our current understanding of the relationship between vitamin D and bone loss in HIV and the impact of vitamin D supplementation in this patient group.

RECENT FINDINGS

Although data are conflicting as to whether vitamin D deficiency is more prevalent among HIV-infected individuals than in the general population, there are several reasons for why this patient group may be at heightened risk. Studies linking vitamin D deficiency to bone loss in HIV are limited; however, data from randomized clinical trials suggest a benefit of vitamin D supplementation for the prevention of bone loss with ART initiation and for the treatment of bone loss with bisphosphonate therapy.

SUMMARY

There are too limited data to recommend universal screening of vitamin D status or supplementation to all HIV-infected individuals. However, testing 25-hydroxyvitamin D levels in those at risk for deficiency and treating patients found to be deficient or initiating ART or bisphosphonate therapy should be considered. Further study on vitamin D supplementation is needed regarding the potential benefit on immune activation and restoration in this patient group.

The Effects of First-Line Anti-Tuberculosis Drugs on the Actions of Vitamin D in Human Macrophages

Tuberculosis (TB) is a major global health problem. Patients with TB have a high rate of vitamin D deficiency, both at diagnosis and during the course of treatment with anti-tuberculosis drugs. Although data on the efficacy of vitamin D supplementation on Mycobacterium tuberculosis (Mtb) clearance is uncertain from randomized controlled trials (RCTs), vitamin D enhances the expression of the anti-microbial peptide human cathelicidin (hCAP18) in cultured macrophages in vitro. One possible explanation for the mixed (primarily negative) results of RCTs examining vitamin D treatment in TB infection is that anti-TB drugs given to enrolled subjects may impact actions of vitamin D to enhance cathelicidin in macrophages. To address this hypothesis, human macrophage-like monocytic (THP-1) cells were treated with varying doses of first-line anti-tuberculosis drugs in the presence of the active form of vitamin D, 1N1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃). The expression of hCAP18 was determined by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). 1,25(OH)₂D₃ strongly induced expression of hCAP18 mRNA in THP-1 cells (fold-change from control). The combination of the standard 4-drug TB therapy (isoniazid, rifampicin, pyrazinamide and ethambutol) in the cultured THP-1 cells demonstrated a significant decrease of hCAP18 mRNA at the dosage of 10 ug/mL. In 31 subjects with newly diagnosed drug-sensitive TB randomized to either high-dose vitamin D₃ (1.2 million IU over 8 weeks, n=13) versus placebo (n=18), there was no change from baseline to week 8 in hCAP18 mRNA levels in peripheral blood mononuclear cells or in plasma concentrations of LL-37, the protein product of hCAP18.These data suggest that first-line anti-TB drugs may alter the vitamin D-dependent increase in hCAP18 and LL-37 human macrophages.

Vitamin D Status in Infants with Two Different Wheezing Phenotypes

OBJECTIVE

To investigate vitamin D levels in patients with recurrent wheeze at early ages of childhood.

METHODS

In the present cross-sectional study, serum 25-hydroxy vitamin D [25 (OH)D], levels which is known as an indicator of vitamin D adequacy, was examined in infants with three or more wheezing attacks.

RESULTS

A total of 186 infants with recurrent wheezing were included in the study along with 118 healthy control peers. The recurrent wheezing study participants were classified into two groups according to Asthma Predictive Index (API) positivity and compared to control subjects regarding their serum vitamin D status. The API negative group had the lowest mean serum 25 (OH)D level (n = 121; 22.71 ± 10.76 ng/ml) followed by API positive group (n = 65; 24.08 ± 9.02 ng/ml) compared to healthy group (26.24 ± 11.88 ng/ml) (p < 0.05). In addition, higher vitamin D deficiency was observed in infants in API negative group (52.1 %; p < 0.01) and API positive group (38.5 %; p < 0.05) than control group (31.4 %).

CONCLUSIONS

Low levels of 25 (OH)D were detected in infants with two different phenotypes of recurrent wheeze. Vitamin D deficiency may play a role in the pathogenesis of infants with recurrent wheezing.

Vitamin D Deficiency in Egyptian Systemic Lupus Erythematosus Patients: How Prevalent and Does It Impact Disease Activity?

BACKGROUND

The emerging role of vitamin D in immunology and autoimmune disorders has been a worldwide interest in the last decade. Systemic lupus erythematosus (SLE) patients are particularly at a delicate position predisposing them to suffer from vitamin D deficiency due to the multiple risk factors accompanying the disease. Whether vitamin D deficiency is also involved as a risk factor for developing SLE and affecting its course is a considerable concern.

OBJECTIVES

The objective of this study was to estimate the prevalence of vitamin D deficiency in SLE patients and its relation to disease.

MATERIALS AND METHODS

In our observational cross-sectional study, serum levels of vitamin D [25(OH)D] in 60 SLE patients and 30 age- and sex-matched healthy controls were assessed and estimated for deficiency and insufficiency at 10 and 30 ng/mL, respectively. Disease activity was evaluated by SLE disease activity index (SLEDAI), irreversible organ damage by Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SLICC/ACR DI), and severity by Severity of Disease Index. Fatigue was measured by visual analog scale.

RESULTS

Significantly lower levels of 25(OH)D were found in SLE patients (17.6 ± 6.9 ng/mL) in comparison to controls (79.0 ± 28.7 ng/mL), with a statistically high significant difference (t = -11.2, P < 0.001). High prevalence of vitamin D insufficiency and deficiency was detected as 73.3% and 23.3%, respectively. Vitamin D had a highly significant negative correlation with SLEDAI (r = -0.495, P < 0.001), SLICC (r = -0.431, P < 0.05), and fatigue (r = -0.436, P < 0.05).

CONCLUSION

Vitamin D deficiency and insufficiency were found to be prevalent in SLE patients in our study and related to disease activity and fatigue. If needed, routine screening and consequent repletion of vitamin D are recommended in SLE patients. Restoring adequate vitamin D levels in SLE patients should be more explored as a potential yet simple measure to their usual management to improve their condition.

Genotyping of vitamin D receptor gene polymorphisms using mismatched amplification mutation assay in neonatal sepsis patients of Odisha, eastern India

Vitamin D has potent antimicrobial and anti-inflammatory properties. Vitamin D deficiency has been shown to be associated with the risk of vulnerability to different infectious diseases, such as neonatal sepsis. Polymorphisms in vitamin D receptor (VDR) gene can influence the expression of vitamin D in individuals. Hence, it is essential to study the vitamin D status and VDR gene polymorphisms for assessing neonatal sepsis risk. In this study, we assessed the serum 25(OH)D, the main circulating form of vitamin D and VDR polymorphism on 120 subjects in a case-control approach, recruiting 60 subjects in each category. We genotyped Fok1, Bsm1, Apa1 and Taq1 gene polymorphisms in VDR by developing a unique mismatch amplification mutation assay (MAMA) and studied their association in both populations. VDR-MAMA primers were designed by addition of dual mismatches (DM) near the 3' end and were selected based on high ΔCt values in comparison to single mismatch (SM) primers using SYBR-Green RT-PCR, which were eventually used for VDR genotyping. Genotyping was also performed using PCR-RFLP for further confirmation. Serum 25(OH)D ELISA revealed that cases were vitamin D insufficient (Median=12.16ng/ml, 95% CI: 3.84-22.22) and controls were vitamin D sufficient (Median=30.22ng/ml, 95% CI: 20.08-46.78; p<0.0001) respectively, which indicated that vitamin D insufficiency was mostly prevalent in cases. We found no evidence of association between genotypes of the Apa1 polymorphism and neonatal sepsis or 25(OH)D serum levels. The distributions of the Fok1, Bsm1, and Taq1 genotypes were not consistent with Hardy-Weinberg equilibrium in the control group. Future studies in larger populations are required to establish whether the VDR polymorphisms can be potentially used as genetic markers for early screening towards predisposition to neonatal sepsis risk. In this study, we describe a simple, inexpensive and rapid screening of VDR gene polymorphisms using VDR MAMA-PCR, which can be used in both clinical and research laboratories.

Association Between Acute Infectious Mononucleosis and Vitamin D Deficiency

Epstein-Barr virus and vitamin D both have been implicated in the pathogenesis of autoimmune diseases, especially multiple sclerosis (MS). Vitamin D influences both innate and adaptive immune responses and has been linked to increased susceptibility to other viral infections such as influenza. Here we aimed to examine the association between vitamin D and acute infectious mononucleosis (IM).This study is a case-control study that was conducted on IM patients and a control group of healthy individuals at infectious disease clinics of Isfahan University of Medical Sciences. Patients were recruited from January to December 2014. The viral capsid antigen (VCA) IgM titer and vitamin D levels were measured at the time of acute infection in IM patients. We also measured vitamin D levels in healthy controls recruited during the same period of time. A total number of 60 IM patients with the mean age of 23.26 ± 7.59 and a healthy control group with the mean age of 25.13 ± 6.72 were enrolled. In the IM patients, there was no significant association between 25(OH) D3 levels and VCA IgM titers (r = 0.190, p = 0.146). Mean 25(OH) D3 levels in IM patients were significantly lower than in the control group (15.61 ± 9.72 vs. 21.41 ± 12.64, p = 0.006). Our findings showed significantly lower vitamin D levels in IM patients at the time of infection than in the control group, providing some evidence that the two major risk factors for autoimmune diseases (e.g., MS) might not be independent risk factors.

Vitamin D status in children and adolescents with autoimmune thyroiditis

BACKGROUND

Vitamin D deficiency is a global health problem. Its role as an immune modulator has been recently emphasized. There is increasing evidence for the significant role of vitamin D in reducing the incidence of autoimmune diseases. However, little is known about the status of vitamin D in children and adolescents with autoimmune thyroiditis (AIT).

OBJECTIVE

The goal of the present study was to assess vitamin D status in Egyptian children and adolescents with AIT and to explore its relation to biomarkers of autoimmunity and thyroid function.

DESIGN

A prevalence case-control study that included 56 children with AIT and 56 healthy, age- and sex-matched subjects that served as the control group. The following was done for all participants: thorough history, physical examination, thyroid ultrasound, measurement of thyroid-stimulating hormone (TSH), free thyroxin (FT4), anti-thyroid peroxidase antibodies (TPOAb), anti-thyroglobulin antibody (TgAb) and assessment of serum 25-hydroxy vitamin D (25OHD) level.

RESULTS

Overt hypothyroidism was detected in 42/56 while subclinical hypothyroidism was detected in 14/56 of the studied patients. Vitamin D deficiency rate was significantly higher in the AIT group compared to the control subjects (71.4 vs 21.4 %, P < 0.001). In AIT group, the mean level of 25OHD was significantly lower compared to the control group (16.2 ± 8.2 vs 33.9 ± 12.7 nmol/L, P < 0.001). The difference was more evident in patients with overt hypothyroidism than those with subclinical hypothyroidism (P < 0.01). There were significant negative correlations between serum 25OHD and age, duration of the disease, BMI, anti-TPOAb, anti-TGAb and TSH (P < 0.001 each). On the other hand, serum 25OHD correlated positively with FT4 levels. While 25OHD level was an independent risk factor for AIT, it failed to qualify as an independent risk for the progression of AIT to overt hypothyroidism after adjustment for other potential confounding factors; age, sex and BMI.

CONCLUSIONS

Low serum vitamin D is significantly associated with AIT in Egyptian children. However, vitamin D level is not an independent risk for the progression of AIT to overt hypothyroidism. BMI may have an influence on serum 25OHD levels.

An oral high dose of cholecalciferol restores vitamin D status in deficient postmenopausal HIV-1-infected women independently of protease inhibitors therapy: a pilot study

The best repletion and maintenance dosing regimens with cholecalciferol in vitamin D-deficient HIV-1 patients remain unknown. Protease inhibitors (PIs) have been shown to inhibit vitamin D 1α- and 25α-hydroxylation in hepatocyte and monocyte cultures. We therefore evaluated the effect of a single high dose of cholecalciferol in vitamin D-deficient HIV-1 postmenopausal women undergoing treatment with highly active anti-retroviral therapy (cART), with and without PIs. Forty HIV-1 postmenopausal women treated with cART, with hypovitaminosis D (<20 ng/ml), were enrolled. We measured serum changes of 25-hydroxyvitamin D [25(OH)D]; 1,25-dihydroxyvitamin D [1,25(OH)2D], parathyroid hormone (PTH), serum calcium, and urinary calcium excretion following a loading dose of 600,000 IU of cholecalciferol after 3, 30, 60, 90, and 120 days. Patients were divided into two groups, whether or not they were taking PI. A significant increase in mean 25(OH)D and 1,25(OH)2D levels at day 3 and throughout the entire observation period was found in both groups (p < 0.001). PTH levels concomitantly decreased in both groups (p < 0.001). Mean albumin-adjusted serum calcium increases with respect to baseline were significant only at day 3 and day 30 for both groups (p < 0.01). Considering remaining parameters, there were no significant differences between the groups at any time, by two-way RM ANOVA. An oral dose of 600,000 IU of cholecalciferol in HIV-1 postmenopausal women rapidly increases 25(OH)D and 1,25(OH)2D levels reducing PTH levels, regardless of the presence of PIs in the cART scheme.

The Active Metabolite of Vitamin D3 as a Potential Immunomodulator

In the past, vitamin D was known for its classical, skeletal action as a regulator of calcium and bone homoeostasis. Currently, vitamin D was found to have a role in numerous physiological processes in the human body; thus, vitamin D has pleiotropic activity. The studies carried out in the past two decades showed the role of vitamin D in the regulation of immune system functions. Basically, these effects may be mediated not only via endocrine mechanism of circulating calcitriol but also via paracrine one (based on cell-cell communication that leads to production of signal inducing the changes in nearby/adjacent cells and modulating their differentiation or behaviour) and intracrine mechanism (the action of vitamin D inside a cell) of 1,25-dihydroxycholecalciferol (1,25(OH)2 D3 ) synthetized from its precursor 25-hydroxyvitamin D3 (25(OH)D3 ). Both vitamin D receptor (VDR) and 25-hydroxyvitamin D3 1-α-hydroxylase (CYP27B1) are expressed in several types of immune cells (i.e. antigen presenting cells, T and B cells), and thus, they are able to synthetize the bioactive form of vitamin D that modulates both the innate and adaptive immune system. This review discusses the role of vitamin D as regulator of immune system, and our understanding of how vitamin D regulates both adaptive and innate immunity as well as inflammatory cascade on the cellular level.

Determination of 1,25-dihydroxyvitamin D2 and 1,25-dihydroxyvitamin D3 in human serum using liquid chromatography with tandem mass spectrometry

Vitamin D plays important roles in skeletal metabolism and many other diseases, including chronic renal failure, hypoparathyroidism, sarcoidosis and rickets. 1α,25-dihydroxy vitamin D (1α,25(OH)2D), the active form of vitamin D, exhibits an extremely low serum concentration, which makes its quantification very challenging. High performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) is considered to be the "gold standard" for the determination of these chemicals, which are found in low concentrations in the serum, but conventionally, it needs tedious sample pretreatment procedures, such as solid phase extraction and derivatization. Herein, we describe a simple and rapid HPLC-MS/MS method for the simultaneous quantification of 1α,25-dihydroxy vitamin D3 (1α,25(OH)2D3) and 1α,25-dihydroxy vitamin D2 (1α,25(OH)2D2). The analytes were extracted from the matrix by liquid-liquid extraction, centrifuged to dryness and reconstituted with 75% methanol. Lithium acetate was employed to improve the ionization efficiency of 1α,25(OH)2D. The assay was sensitive with a low limit of quantitation of 10.0pg/mL for both 1α,25(OH)2D3 and 1α,25(OH)2D2 using a 0.5mL sample aliquot. Linearity was obtained over the range of 10.0pg/mL to 500pg/mL. Both the inter-assay and intra-assay precisions were <15%, and the analytical recoveries were within 100±5%. The performance evaluation of this assay demonstrated that it was a practical, sensitive and specific method for measuring the serum 1α,25(OH)2D3 and 1α,25(OH)2D2 concentrations.

Vitamin D Activation and Function in Human Corneal Epithelial Cells During TLR-Induced Inflammation

PURPOSE

Vitamin D is recognized to be an important modulator of the immune system. In the eye, studies have shown that deficiencies and genetic differences in vitamin D-related genes have a significant impact on the development of various ocular diseases. Our current study examines the ability of human corneal epithelial cells (HCEC) to activate vitamin D and the effect of vitamin D treatment on antimicrobial peptide production and cytokine modulation during inflammation, with the ultimate goal of using vitamin D therapeutically for corneal inflammation.

METHODS

Human corneal epithelial cells were treated with 10-7M vitamin D3 (D3) or 25-hydroxyvitamin D3 (25D3) for 24 hours and 1,25-dihydroxyvitamin D3 (1,25D3) detected by immunoassay. Human cathelicidin (LL-37) expression was examined by RT-PCR, immunoblot, and immunostaining following 1,25D3 treatment and antimicrobial activity of 1,25D3-treated cells was determined. Cells were stimulated with TLR3 agonist polyinosinic-polycytidylic acid (Poly[I:C]) for 24 hours and cytokine levels measured by RT-PCR, ELISA, and Luminex. Immunostaining determined expression of vitamin D receptor (VDR) and retinoic acid inducible gene-1 receptor (RIG-1) as well as NF-κB nuclear translocation.

RESULTS

When treated with inactive vitamin D metabolites, HCEC produced active 1,25D3, leading to enhanced expression of the antimicrobial peptide, LL-37, dependent on VDR. 1,25-D3 decreased the expression of proinflammatory cytokines (IL-1β, IL-6, TNFα, and CCL20) and MMP-9 induced by Poly(I:C) as well as pattern recognition receptor expression (TLR3, RIG-1, MDA5). However, early activation of NF-κB was not affected.

CONCLUSIONS

These studies demonstrate the protective ability of vitamin D to attenuate proinflammatory mediators while increasing antimicrobial peptides and antipseudomonas activity in corneal cells, and further our knowledge on the immunomodulatory functions of the hormone.

Vitamin D level and vitamin D receptor genetic variations contribute to HCV infection susceptibility and chronicity in a Chinese population

Vitamin D and vitamin D receptor (VDR) are involved in multiple immune-mediated disorders including chronic hepatitis C virus (HCV) infection. The aim of this study was to determine the association between plasma vitamin D level, VDR genetic polymorphisms and risk of HCV infection susceptibility and chronicity. Seven single nucleotide polymorphisms (SNPs) in VDR gene were genotyped and plasma 25-hydroxyvitamin D [25(OH)D] levels were measured in a Han Chinese population of 898 HCV persistent infection cases, 558 spontaneous clearance subjects and 1136 uninfected controls with high risk of HCV infection. In this case-control study, the average plasma 25(OH)D level in persistent infection patients was significantly lower than that in spontaneous clearance cases (P=0.039) and controls (P=0.005). Logistic analyses indicated that rs7975232-C, rs2239185-T and rs11574129-T alleles were significantly associated with a decreased risk of HCV infection susceptibility (all PBonferroni<0.05, in additive/dominant models; Ptrend=9.000×10(-4), combined effects in a locus-dosage manner). The protective effects of three favorable alleles were more evident among males, females and subjects aged ≤50years (all P<0.05). Haplotype analyses suggested that compared with the most frequent haplotype Ars7975232Trs731236Crs11574129, CTT was correlated with a reduced risk of HCV infection susceptibility (P=2.200×10(-3)). These findings implied that low vitamin D levels might be associated with an increased risk for HCV infection and chronicity, and favorable VDR variants (rs7975232-C, rs2239185-T and rs11574129-T) might contribute to a decreased susceptibility to HCV infection in a high-risk Chinese population.

Stability of Vitamin D3 in fortified yoghurt and yoghurt drink (Doogh)

Background:

Vitamin D deficiency and insufficiency are recognized as a worldwide problem with serious consequences. Fortification of foods with Vitamin D is a certain approach to improve serum Vitamin D status if the stability of vitamin in the foodstuffs was controlled. The purpose of this study was to examine the stability of Vitamin D₃ added to low-fat yogurt and yogurt drink “Doogh” during the products shelf-life.

Materials and Methods:

Two kinds of Vitamin D₃, water- and oil-dispersible forms, suitable for food fortification, were compared to find out whether they show different stability in the products. The products were packed in opaque or translucent containers. The content of Vitamin D₃ was determined by high performance liquid chromatography method.

Results:

Vitamin D was not affected by the heat treatment (pasteurization) and other processes (homogenization and fermentation). Both water- and oil-dispersible forms were stable during the shelf-life of yogurt samples packed in opaque containers. The Vitamin D₃ content of yogurt fortified with water-dispersible form and packed in translucent containers was not stable during the shelf-life and significantly reduced after 1, 2, and 3 weeks of storage compared to the day 0. The Vitamin D₃ content of samples fortified with the oil-dispersible form packed in the same container was only stable after 1-week and significantly reduced after 2 and 3 weeks of storage. The Vitamin D₃ content of Doogh packed in the opaque containers remained stable during the shelf-life while it was not stable in the samples packed in translucent containers.

Conclusion:

The results suggested that both forms of Vitamin D are suitable for fortification, and opaque container is a better choice for packaging of the product.

1,25-Dihydroxyvitamin D increases the gene expression of enzymes protecting from glucolipotoxicity in peripheral blood mononuclear cells and human primary endothelial cells

Besides its classical function as an orchestrator of calcium and phosphorus homeostasis, vitamin D also affects insulin secretion and tissue efficiency. A number of studies have consistently reported the inverse relationship between vitamin D deficiency and type 2 diabetes. Activation of certain metabolic pathways and down-stream transcription factors may protect from glucolipotoxicity and their targeted activation -e.g. by vitamin D - might explain the detrimental role of vitamin D deficiency in diabetes. The aim of the study was to quantify gene and protein expression of selected enzymes involved in the protection from glucolipotoxicity, specifically glyoxalase 1 (GLO1), and other enzymes with antioxidant activity - hemoxygenase (HMOX), thiamin pyrophosphokinase (TPK1) and transketolase (TKT), under normo- and hyperglycemic conditions and upon addition of vitamin D in peripheral blood mononuclear cells (PBMCs) and human umbilical vein endothelial cells (HUVEC). The results of our study indicate that the active form of vitamin D regulates gene expression of enzymes opposing the harmful effect of glucolipotoxicity whose activities appear to be suppressed by hyperglycemia. However, we were unable to confirm this effect on protein expression. While we cannot speculate on the effect of vitamin D on diabetes itself our results support its role in the protection against existing glucolipotoxicity therefore possibly translating into the prevention of development of diabetic complications.

More than metabolic: Considering the broader paleoepidemiological impact of vitamin D deficiency in bioarchaeology

Vitamin D deficiency has traditionally been viewed as a metabolic bone disease by bioarchaeologists and considered primarily in terms of the development of specific musculoskeletal changes used for diagnosis in paleopathological research. These skeletal manifestations are usually interpreted as representing general ill-health. Clinical research shows that vitamin D is also integral to a number of extra-skeletal physiological processes including immunoregulation, blood pressure homeostasis, cell division, and programmed cell death. Vitamin D deficiency and sub-clinical insufficiency are thought to be risk factors for infectious and autoimmune diseases, as well as certain cancers and cardiovascular diseases. Epidemiological work indicates that the skeletal manifestations of vitamin D deficiency represent the extreme end of a spectrum of morbidity associated with negative health outcomes, including increased risk for secondary tuberculosis. This article provides a review of clinical research on the extra-skeletal roles of vitamin D and the pathological consequences of poor vitamin D status. Additionally, it presents an interpretive model for bioarchaeological analyses of rickets and osteomalacia for consideration of the whole-body impact of poor vitamin D nutriture and possible comorbidities that may have affected the wider population. Am J Phys Anthropol 160:183-196, 2016. © 2016 Wiley Periodicals, Inc.

C–C motif ligand 11 reduction in CLL patients serum after vitamin D supplementation

Background: Vitamin D (VD) deficiency results in a worse prognosis in patients with chronic lymphocytic leukemia (CLL) and may affect the production of cytokines. Nonetheless, there is the lack of studies dealing with VD supplementation and its impact on chemokines in CLL patients.

Aim: The primary endpoint of our interventional study was to evaluate the effect of cholecalciferol supplementation on serum chemokines levels in CLL patients.

Materials and methods: Eighteen subjects with CLL were enrolled for the study. Six-month-long cholecalciferol supplementation was performed in CLL patients with serum 25-OH-D₃ levels below 30 ng/ml. Cytokines levels were assessed at the beginning of the study and after 6 months. Baseline measurements of cytokines were compared to those in apparently healthy controls.

Results: Increased levels of CCL2, CCL3, CCL4, CXCL8, CXCL10, TNFα, bFGF, G-CSF, and VEGF were found in CLL patients in comparison with the healthy controls. In the course of the VD supplementation a decrease in serum levels of chemokines CCL11, CCL3, and cytokine PDGF-BB was observed. The decrease of CCL11 was found in CLL patients on VD supplementation solely, whereas the decrease of CCL3 and PDGF-BB was observed in CLL subjects on both chemotherapy and VD supplementation.

Conclusion: The VD supplementation may exert beneficial effect on chemokines levels in CLL patients with VD deficiency.

A randomized controlled trial on the effect of vitamin D3 on inflammation and cathelicidin gene expression in ulcerative colitis patients

BACKGROUND

Inflammatory bowel disease (IBD) is an intestinal chronic inflammatory condition and includes Crohn's disease (CD) and ulcerative colitis (UC). It has been proposed that Vitamin D supplementation may have a beneficial role in IBD.

AIM

To characterize the effects of Vitamin D on cathelicidin (hCAP/LL37) gene expression, ESR, and serum hs-CRP levels.

MATERIALS AND METHODS

Ninety UC patients on remission were randomized to receive 300,000 IU intramuscular Vitamin D or 1 mL normal saline as placebo, respectively. Before and 90 days after intervention, serum levels of 25 (OH)-Vitamin D3, PTH, Calcium, ESR, and hs-CRP were measured. Cathelicidin gene expression was also quantified using qRT-PCR.

RESULTS

Baseline serum 25-OH-Vitamin D3 levels were not different between the two groups and after intervention, increased only in Vitamin D group (P < 0.001). Hs-CRP levels were lower in Vitamin D group after intervention (Before: 3.43 ± 3.47 vs 3.86 ± 3.55 mg/L, P = 0.56; after: 2.31 ± 2.25 vs 3.90 ± 3.97 mg/L, P= 0.023). ESR decreased significantly in Vitamin D group (Before: 12.4 ± 6.1 vs 12.1 ± 5.3 mm/h, P= 0.77; after: 6.7 ± 4.5 vs 11.4 ± 5.5 mm/h, P< 0.001). The mean fold change in hCAP18 gene expression in Vitamin D group was significantly higher than placebo group. (Mean ± SD: 3.13 ± 2.56 vs 1.09 ± 0.56; median ± interquartile range: 2.17 ± 3.81 vs 0.87 ± 0.53, P< 0.001).

CONCLUSION

Decreases in ESR and hs-CRP levels and increase in LL37 gene expression support the hypothesis that Vitamin D supplementation may have a beneficial role in UC patients.

The role of Vitamin D in immuno-inflammatory responses in Ankylosing Spondylitis patients with and without Acute Anterior Uveitis

Hypothesis:Abnormal Vitamin D (Vit D) level could have consequences on the immuno-inflammatory processes in Ankylosing Spondylitis (AS). Aim:The purpose of this study was to analyze the role of Vitamin D in the interplay between immune and inflammation effectors in AS associated-Acute Anterior Uveitis (AAU). Methods and Results:25-hydroxyvitamin D (Vit D), LL-37 peptide, IL-8 and Serum Amyloid A (SAA) were identified and quantified in the serum/ plasma of thirty-four AS patients [eleven AS patients presenting AAU (AAU AS patients) and twenty-three AS patients without AAU (wAAU AS patients)] and eighteen healthy individuals (Control) using enzyme-linked immunosorbent assay. Acute-phase SAA level was significantly higher in AS patients compared to Controls. Contrary with wAAU AS patients, significantly elevated levels of IL-8, and diminished levels of Vit D characterized AAU AS patients. Regarding LL-37, its level decreased concomitantly with the level of Vit D. When AS patients were subgrouped based on AAU presence or on Vit D level, important associations between immuno-inflammatory assessed markers and AS features were noticed. Generally, Vit D levels were associated indirectly with leukocytes/ neutrophils number or with ESR, CRP, and Fibrinogen levels. The levels of SAA and IL-8 associated directly with AAU or with AAU relapses, especially in AS patients with Vit D insufficiency, while SAA associated directly with infection/ inflammatory markers and with disease activity indexes or with the degree of functional limitation. Discussion:Altered levels of Vit D affect the balance between LL-37, IL-8 and SAA, suggesting an association with AAU, an extra-articular manifestation of AS. Abbreviations:Vit D = Vitamin D, AS = Ankylosing Spondylitis, AAU = Acute Anterior Uveitis, AAU AS = AS patients with AAU, wAAU AS = AS patients without AAU, SSZ = Sulphasalazine, Leu = Leukocytes, Neu = Neutrophils.

Impact of beta thalassemia on maxillary sinuses and sino-nasal passages: A case control study

OBJECTIVES

Skeletal changes among beta (β) thalassemia children are well documented, but without available data regarding sino-nasal passages alterations. The authors investigated the maxillary sinuses and sino-nasal passages changes in β-thalassemia children and correlated such changes with the amount of transfused red cells and the erythroid marrow activity.

METHODS

Clinical analyses including otorhinolaryngical examination (ORL) were obtained in twenty β-thalassemia children and 20 matched healthy controls. Hemoglobin (Hb), serum ferritin, soluble transferrin receptor (sTfR) levels and bone mineral density of the lumbar spine (BMD ls) were assayed. The two groups were analyzed for the CT image parameters: bone thickness, anterior and posterior choanae diameters, extramedullary hematopoiesis and chronic rhinosinusitis (CRS) RESULTS: Nasal congestion/obstruction was identified in 14 (70%) children. Eight patients (40%) had criteria of chronic rhinosinusitis. In comparison with the normal controls, the increase in the roof, floor, medial, anterior, lateral and posterior maxillary bony walls thickness was significantly higher (1.26, 2.46, 2.6, 2.9, 3.23 and 5.34-folds, respectively). The mean posterior choanae horizontal, vertical diameters and their surface area were significantly reduced in the patients compared to the controls. The mean anterior maxillary wall bone thickness directly correlated with sTfR (P=0.047) while that of the posterior wall correlated inversely with Hb level (P=0.013). The mean vertical posterior choanae diameter had positive correlation with the amount of transfused red cells (P=0.001) and negative correlation with sTfR (P=0.001). The Hounsfield unit of maxillary sinus wall had direct relation with BMDls (P=0.003) CONCLUSIONS: Thalassemia children are at risk of different folds increase of maxillary sinuses walls thicknesses utmost at posterior and lateral walls. Other sino-nasal morbidities include diminished posterior choanal diameter, nasal obstruction and CRS. Certain morbidities had relations to the erythroid marrow activity and the transfusion adequacy.

Seasonal Variation in Flares of Intestinal Behçet's Disease

BACKGROUND

There have been numerous investigations into the seasonality of several autoimmune diseases and inflammatory bowel disease in an effort to better understand the epidemiology and pathogenesis of these conditions. However, the relationship between the season and disease activity of intestinal Behçet's disease has not been investigated.

AIMS

This study aimed to evaluate the seasonal pattern of exacerbations of intestinal Behçet's disease.

METHODS

We evaluated 268 consecutive patients with intestinal Behçet's disease who were diagnosed and treated between November 1990 and March 2010 at Severance Hospital, Yonsei University, Seoul, Korea. Patient demographics, onset of symptoms, total number of relapses, and the month of each relapse were recorded. The relationship between the season and flares of intestinal Behçet's disease was analyzed.

RESULTS

A total of 339 relapses occurred in 142 patients (53 %). The median age at diagnosis was 39 (10-73) years; the median follow-up duration was 74 (7-372) months. The peak seasons for relapse were spring and autumn, especially the months of May and September (p value <0.001). Compared with winter, spring and autumn had higher rates of flares (HR 1.92 and 1.91, respectively, p value <0.001).

CONCLUSIONS

In this study, intestinal Behçet's disease demonstrated a biphasic pattern (peaks in spring and autumn) in exacerbations of disease, suggesting that seasonal or exogenous factors may be involved in the flares of intestinal Behçet's disease.

The importance of vitamin D in the pathology of bone metabolism in inflammatory bowel diseases

Etiological factors of bone metabolism disorders in inflammatory bowel diseases have been the subject of interest of many researchers. One of the questions often raised is vitamin D deficiency. Calcitriol acts on cells, tissues and organs through a vitamin D receptor. The result of this action is the multi-directional effect of vitamin D. The reasons for vitamin D deficiency are: decreased exposure to sunlight, inadequate diet, inflammatory lesions of the intestinal mucosa and post-gastrointestinal resection states. This leads not only to osteomalacia but also to osteoporosis. Of significance may be the effect of vitamin D on the course of the disease itself, through modulation of the inflammatory mechanisms. It is also necessary to pay attention to the role of vitamin D in skeletal pathology in patients with inflammatory bowel diseases and thus take measures aimed at preventing and treating these disorders through the supplementation of vitamin D.

Vitamin D receptor pathway is required for probiotic protection in colitis

Low expression of vitamin D receptor (VDR) and dysfunction of vitamin D/VDR signaling are reported in patients with inflammatory bowel disease (IBD); therefore, restoration of VDR function to control inflammation in IBD is desirable. Probiotics have been used in the treatment of IBD. However, the role of probiotics in the modulation of VDR signaling to effectively reduce inflammation is unknown. We identified a novel role of probiotics in activating VDR activity, thus inhibiting inflammation, using cell models and VDR knockout mice. We found that the probiotics Lactobacillus rhamnosus strain GG (LGG) and Lactobacillus plantarum (LP) increased VDR protein expression in both mouse and human intestinal epithelial cells. Using the VDR luciferase reporter vector, we detected increased transcriptional activity of VDR after probiotic treatment. Probiotics increased the expression of the VDR target genes, such as antimicrobial peptide cathelicidin, at the transcriptional level. Furthermore, the role of probiotics in regulating VDR signaling was tested in vivo using a Salmonella-colitis model in VDR knockout mice. Probiotic treatment conferred physiological and histologic protection from Salmonella-induced colitis in VDR(+/+) mice, whereas probiotics had no effects in the VDR(-/-) mice. Probiotic treatment also enhanced numbers of Paneth cells, which secrete AMPs for host defense. These data indicate that the VDR pathway is required for probiotic protection in colitis. Understanding how probiotics enhance VDR signaling and inhibit inflammation will allow probiotics to be used effectively, resulting in innovative approaches to the prevention and treatment of chronic inflammation.

Immune Modulation by Vitamin D and Its Relevance to Food Allergy

Apart from its classical function in bone and calcium metabolism, vitamin D is also involved in immune regulation and has been linked to various cancers, immune disorders and allergic diseases. Within the innate and adaptive immune systems, the vitamin D receptor and enzymes in monocytes, dendritic cells, epithelial cells, T lymphocytes and B lymphocytes mediate the immune modulatory actions of vitamin D. Vitamin D insufficiency/deficiency early in life has been identified as one of the risk factors for food allergy. Several studies have observed an association between increasing latitude and food allergy prevalence, plausibly linked to lower ultraviolet radiation (UVR) exposure and vitamin D synthesis in the skin. Along with mounting epidemiological evidence of a link between vitamin D status and food allergy, mice and human studies have shed light on the modulatory properties of vitamin D on the innate and adaptive immune systems. This review will summarize the literature on the metabolism and immune modulatory properties of vitamin D, with particular reference to food allergy.

Tight junction CLDN2 gene is a direct target of the vitamin D receptor

The breakdown of the intestinal barrier is a common manifestation of many diseases. Recent evidence suggests that vitamin D and its receptor VDR may regulate intestinal barrier function. Claudin-2 is a tight junction protein that mediates paracellular water transport in intestinal epithelia, rendering them “leaky”. Using whole body VDR^-/- mice, intestinal epithelial VDR conditional knockout (VDR^ΔIEC) mice, and cultured human intestinal epithelial cells, we demonstrate here that the CLDN2 gene is a direct target of the transcription factor VDR. The Caudal-Related Homeobox (Cdx) protein family is a group of the transcription factor proteins which bind to DNA to regulate the expression of genes. Our data showed that VDR-enhances Claudin-2 promoter activity in a Cdx1 binding site-dependent manner. We further identify a functional vitamin D response element (VDRE) 5΄-AGATAACAAAGGTCA-3΄ in the Cdx1 site of the Claudin-2 promoter. It is a VDRE required for the regulation of Claudin-2 by vitamin D. Absence of VDR decreased Claudin-2 expression by abolishing VDR/promoter binding. In vivo, VDR deletion in intestinal epithelial cells led to significant decreased Claudin-2 in VDR^-/- and VDR^ΔIEC mice. The current study reveals an important and novel mechanism for VDR by regulation of epithelial barriers.

Association of VDR and CYP2R1 Polymorphisms with Mite-Sensitized Persistent Allergic Rhinitis in a Chinese Population

As recent studies have described an association between vitamin D and allergic rhinitis, we hypothesized that vitamin D pathway-related genes may be candidate genes for susceptibility to allergic rhinitis. Thus, we sought to evaluate whether polymorphisms in the vitamin D receptor (VDR) and CYP2R1 genes are associated with mite-sensitized persistent allergic rhinitis (PER) in a Han Chinese population. A hospital-based case-control study consisting of 519 patients with mite-sensitized PER and 447 healthy controls was conducted. Five single nucleotide polymorphisms (SNPs) in VDR and CYP2R1 were selected for genotyping. The genotype and allele frequencies of rs9729, rs2228570, rs1544410, and rs731236 in VDR as well as rs2060793 in CYP2R1 were not significantly associated with susceptibility to mite-sensitized PER. After stratification analyses, however, both the CT and CT/TT genotypes of rs2228570 in VDR exhibited a significantly decreased risk (CT: adjusted odds ratio (OR)=0.58, 95% confidence intervals (CI)=0.37-0.91; CT/TT: adjusted OR=0.61, 95% CI=0.40-0.93) of mite-sensitized PER, while the AA genotype of rs2060793 in CYP2R1 exhibited a significantly increased risk (adjusted OR=1.85, 95% CI=1.03-3.34) of PER in the age subgroup of <16 years old. Both the AG and AG/GG genotypes of rs731236 in VDR exhibited a significantly decreased risk (AG: adjusted OR=0.43, 95% CI=0.21-0.89; AG/GG: adjusted OR=0.46, 95% CI=0.23-0.94) of PER in the female subgroup. Analysis of the locus-locus interactions of VDR and CYP2R1 revealed two models that involved combined SNPs of VDR and CYP2R1 were statistically significant (P<0.05). Our data suggest that age and gender may have an impact on the association of three SNPs (rs2228570, rs731236, and rs2060793) in genes of the vitamin D pathway with the risk of mite-sensitized PER in this Chinese population. The VDR and CYP2R1 variants may be involved in genetic interactions in the pathogenesis of PER.

Vitamin D levels and cytokine profiles in patients with systemic lupus erythematosus

OBJECTIVES

To evaluate the expression of Th1, Th2, and Th17 cytokines in patients with systemic lupus erythematosus (SLE), and verify the association between serum cytokine levels and vitamin D concentration.

METHODS

The sample consisted of 172 patients with SLE. 25-Hydroxyvitamin D (25(OH)D) levels were measured by chemiluminescence and 25(OH)D levels <20 ng/mL were considered to reflect vitamin D deficiency. Serum cytokine levels were measured in once-thawed samples, using a Th1/Th2/Th17 CBA (cytometric beads array) kit.

RESULTS

One hundred and sixty-one (93.6%) patients were women and 128 (74.4%) were of European descent. Mean patient age was 40.5 ± 13.8 years, and mean age at diagnosis was 31.5 ± 13.4 years. At the time of study entry, patients had a median (IQR) SLEDAI of 2 (1-4) and SLICC of 0 (0-1). Mean 25(OH)D concentration was 25.4 ± 11.04 ng/mL. Fifty-nine (34.3%) patients had a vitamin D deficiency. No statistically significant associations were identified between cytokine and vitamin D levels. The most significant finding was a positive correlation between INF-α levels and SLEDAI (r(s) = 0.22, p = 0.04).

CONCLUSION

Although vitamin D deficiencies are highly prevalent in patients with SLE, vitamin D levels were not significantly associated with patient cytokine profiles. The positive correlation between IFN-α levels and SLEDAI showed in this study corroborates other findings in the literature. The present results did not replicate those of in vitro studies of the effect of vitamin D levels on cytokine profiles. Placebo-controlled intervention trials of the effect of vitamin D on cytokine profiles are still required before any definitive conclusions can be drawn regarding the association between these variables.

Serum levels of vitamins A and D, and zinc in children with acute diarrhea: A cross-sectional study

BACKGROUND

Diarrhea is a leading cause of mortality and morbidity during the early life period especially in developing countries. Micronutrients deficiencies have been proposed either as a risk factor or a consequence of diarrhea. Association studies highlight the relation of vitamins and minerals' deficiencies with acute diarrhea. In this regard we aimed to evaluate the status of vitamins A and D, and zinc serum levels in children with acute diarrhea.

METHODS

In this cross sectional study performed in a referral teaching hospital, we measured and compared baseline vitamin A, 25-hydroxy vitamin D (25(OH)D), and zinc serum levels in 25 children admitted with acute diarrhea and 25 other children who were admitted for undergoing elective surgeries.

RESULTS

25-(OH)D levels were significantly lower in the diarrhea group (p=0.03). We were unable to demonstrate a significant difference in the levels of vitamin A and zinc between the case and control groups (p= 0.14 and p=0.07, respectively).

CONCLUSION

We observed lower serum 25(OH)D levels in children with acute diarrhea. Whether this finding indicates a premorbid risk factor or simply a consequence of diarrhea needs further studies. Regardless of the cause and effect relationship, supplementation with vitamin D in acute diarrhea remains as a plausible consideration.

The effect of 14 weeks of vitamin D3 supplementation on antimicrobial peptides and proteins in athletes

Heavy training is associated with increased respiratory infection risk and antimicrobial proteins are important in defence against oral and respiratory tract infections. We examined the effect of 14 weeks of vitamin D3 supplementation (5000 IU/day) on the resting plasma cathelicidin concentration and the salivary secretion rates of secretory immunoglobulin A (SIgA), cathelicidin, lactoferrin and lysozyme in athletes during a winter training period. Blood and saliva were obtained at the start of the study from 39 healthy men who were randomly allocated to vitamin D3 supplement or placebo. Blood samples were also collected at the end of the study; saliva samples were collected after 7 and 14 weeks. Plasma total 25(OH)D concentration increased by 130% in the vitamin D3 group and decreased by 43% in the placebo group (both P = 0.001). The percentage change of plasma cathelicidin concentration in the vitamin D3 group was higher than in the placebo group (P = 0.025). Only in the vitamin D3 group, the saliva SIgA and cathelicidin secretion rates increased over time (both P = 0.03). A daily 5000 IU vitamin D3 supplement has a beneficial effect in up-regulating the expression of SIgA and cathelicidin in athletes during a winter training period, which could improve resistance to respiratory infections.

Environmental influences on systemic lupus erythematosus expression

The etiology of systemic lupus erythematosus (SLE) is unknown, but multiple genetic, epigenetic, and environmental risk factors have been implicated. The inheritance of genes alone is not sufficient for developing SLE, suggesting the influence of environmental triggers on disease expression. Despite the tremendous amount of progress in elucidating potential environmental risk factors for SLE, much more needs to be done. An interdisciplinary approach to studies of the causes and, ultimately, prevention of SLE is needed. This article reviews what is understood about the epidemiology of the relationship between environmental exposures and SLE, in addition to emerging areas of study.

Vitamin D: Implications for ocular disease and therapeutic potential

Vitamin D is a multifunctional hormone that is now known to play a significant role in a variety of biological functions in addition to its traditional role in regulating calcium homeostasis. There are a large number of studies demonstrating that adequate vitamin D levels are important in maintaining health and show that vitamin D is able to be utilized at local tissue sites. In the eye, we have increasing evidence of the association between disease and vitamin D. In this narrative review, we summarize recent findings on vitamin D and its relationship to various ocular pathologies and the therapeutic potential for some of these, as well as examine the basic science studies that demonstrate that vitamin D is biologically relevant in the eye.

Determinants of vitamin D deficiency among undergraduate medical students in Saudi Arabia

BACKGROUND/OBJECTIVES

The objectives of our study were to determine possible factors associated with low vitamin D levels in medical students.

SUBJECTS/METHODS

A cross-sectional study was performed among 255 first- to fifth-year male undergraduate medical students of one of the major universities in Saudi Arabia. Serum 25-hydroxyvitamin D (25(OH)D) levels were measured using electrochemiluminiscence. Multiple logistic regression analysis was performed.

RESULTS

Majority of Saudi medical students (75.2%) had 25(OH)D levels <30 nmol/l, defined as risk for deficiency by the Institute of Medicine. Multivariate analysis showed that the odds of having 25(OH)D serum levels of ⩾ 30 nmol/l were seven times higher both in students who took vitamin D (odds ratio (OR)=7.2, 95% confidence interval (CI)=1.8-29.9, P=0.006) or multivitamin supplements (OR=6.9, 95% CI=1.7-27.3, P=0.006) within 1 year. Students with a history of vitamin D testing >1 year before the study or moderate/vigorous physical activity (PA) had 4.4 (OR=4.4, 95% CI=1.7-11.4, P=0.003) and 2.7-fold (OR=2.7, 95% CI=1.3-5.3, P=0.006) higher odds of having 25(OH)D levels ⩾ 30 nmol/l, respectively. There was no significant association between 25(OH)D serum levels and average time spent outdoors per day (P=0.369) and type of clothing (long-sleeved vs short-sleeved; P=0.800).

CONCLUSIONS

Vitamin D deficiency was highly prevalent in Saudi medical students. Modifiable factors such as vitamin D intake and PA could be targeted for intervention. Further studies with standardized laboratory measurements of 25(OH)D are needed to explore the role of vitamin D testing in behavioral change, which may lead to increased serum 25(OH)D levels.

Conversion from clinically isolated syndrome to multiple sclerosis: A large multicentre study

Background and objective:

We explored which clinical and biochemical variables predict conversion from clinically isolated syndrome (CIS) to clinically definite multiple sclerosis (CDMS) in a large international cohort.

Methods:

Thirty-three centres provided serum samples from 1047 CIS cases with at least two years’ follow-up. Age, sex, clinical presentation, T2-hyperintense lesions, cerebrospinal fluid (CSF) oligoclonal bands (OCBs), CSF IgG index, CSF cell count, serum 25-hydroxyvitamin D3 (25-OH-D), cotinine and IgG titres against Epstein-Barr nuclear antigen 1 (EBNA-1) and cytomegalovirus were tested for association with risk of CDMS.

Results:

At median follow-up of 4.31 years, 623 CIS cases converted to CDMS. Predictors of conversion in multivariable analyses were OCB (HR = 2.18, 95% CI = 1.71–2.77, p < 0.001), number of T2 lesions (two to nine lesions vs 0/1 lesions: HR = 1.97, 95% CI = 1.52–2.55, p < 0.001; >9 lesions vs 0/1 lesions: HR = 2.74, 95% CI = 2.04–3.68, p < 0.001) and age at CIS (HR per year inversely increase = 0.98, 95% CI = 0.98–0.99, p < 0.001). Lower 25-OH-D levels were associated with CDMS in univariable analysis, but this was attenuated in the multivariable model. OCB positivity was associated with higher EBNA-1 IgG titres.

Conclusions:

We validated MRI lesion load, OCB and age at CIS as the strongest independent predictors of conversion to CDMS in this multicentre setting. A role for vitamin D is suggested but requires further investigation.

Vitamin D deficiency and altered bone mineral metabolism in HIV-infected individuals

Although patients with HIV infection are living decades longer than before with the advent of combination antiretroviral therapy, they have an increased rate of co-morbidities associated with chronic HIV, such as osteoporosis, cardiovascular disease, and immune dysfunction. Many of these complications are known to be affected by vitamin D status in the general population. Thus, the high rate of vitamin D deficiency among HIV-infected patients is alarming. Many observational and cohort studies have demonstrated that vitamin D deficiency is associated with these HIV-related complications, but randomized, placebo-controlled trials are limited. This paper reviews recent data on vitamin D deficiency in HIV infection.

Vitamin D deficiency predisposes to adherent-invasive Escherichia coli-induced barrier dysfunction and experimental colonic injury

BACKGROUND

Adherent-invasive Escherichia coli (AIEC) colonization has been strongly implicated in the pathogenesis of Crohn's disease. Environmental triggers such as vitamin D deficiency have emerged as key factors in the pathogenesis of inflammatory bowel diseases. The aim of this study was to investigate the effects of 1,25(OH)2D3 on AIEC infection-induced changes in vivo and in vitro.

METHODS

Barrier function was assessed in polarized epithelial Caco-2-bbe cells grown in medium with or without vitamin D and challenged with AIEC strain LF82. Weaned C57BL/6 mice were fed either a vitamin D-sufficient or -deficient diet for 5 weeks and then infected with AIEC, in the absence and presence of low-dose dextran sodium sulphate. Disease severity was assessed by histological analysis and in vivo intestinal permeability assay. Presence of invasive bacteria was assessed by transmission electron microscopy.

RESULTS

Caco-2-bbe cells incubated with 1,25(OH)2D3 were protected against AIEC-induced disruption of transepithelial electrical resistance and tight-junction protein redistribution. Vitamin D-deficient C57BL/6 mice given a course of 2% dextran sodium sulphate exhibited pronounced epithelial barrier dysfunction, were more susceptible to AIEC colonization, and showed exacerbated colonic injury. Transmission electron microscopy of colonic tissue from infected mice demonstrated invasion of AIEC and fecal microbiome analysis revealed shifts in microbial communities.

CONCLUSIONS

These data show that vitamin D is able to mitigate the deleterious effects of AIEC on the intestinal mucosa, by maintaining intestinal epithelial barrier homeostasis and preserving tight-junction architecture. This study highlights the association between vitamin D status, dysbiosis, and Crohn's disease.

Vitamin D therapy in inflammatory bowel diseases: who, in what form, and how much?

BACKGROUND

The north–south geographical gradient of inflammatory bowel disease (IBD) prevalence, its epidemiology, the genetic association of vitamin D receptor polymorphisms, and results in animal models suggest that vitamin D plays an important role in the pathogenesis of IBD.

AIMS

The purpose of this review was to critically appraise the effectiveness and safety of vitamin D therapy in patients with IBD.

METHODS

MEDLINE, Scopus and Google Scholar were searched from inception to May 20, 2014 using the terms ‘Crohn’s disease’, ‘ulcerative colitis’ and ‘vitamin D’. Results: Vitamin D deficiency is common in patients with IBD. Limited clinical data suggest an association between low vitamin D concentration and increased disease activity in both ulcerative colitis (UC) and Crohn’s disease (CD). To date, only two small open label trials and one randomized controlled trial have shown a positive effect of vitamin D supplementation on disease activity in patients with CD; no effect has been shown for UC. An optimal vitamin D supplementation protocol for patients with IBD remains undetermined, but targeting serum 25-hydroxy vitamin D [25(OH)D] levels between 30 and 50 ng/mL appears safe and may have benefits for IBD disease activity. Depending on baseline vitamin D serum concentration, ileal involvement in CD, body mass index, and perhaps smoking status, daily vitamin D doses between 1800–10,000 international units/day are probably necessary.

CONCLUSION

Increasing preclinical and clinical evidence suggests a role for vitamin D deficiency in the development and severity of IBD. The possible therapeutic role of vitamin D in patients with IBD merits continued investigation.

The role of telomeres and vitamin D in cellular aging and age-related diseases

Aging is a complex biological process characterized by a progressive decline of organ functions leading to an increased risk of age-associated diseases and death. Decades of intensive research have identified a range of molecular and biochemical pathways contributing to aging. However, many aspects regarding the regulation and interplay of these pathways are insufficiently understood. Telomere dysfunction and genomic instability appear to be of critical importance for aging at a cellular level. For example, age-related diseases and premature aging syndromes are frequently associated with telomere shortening. Telomeres are repetitive nucleotide sequences that together with the associated sheltrin complex protect the ends of chromosomes and maintain genomic stability. Recent studies suggest that micronutrients, such as vitamin D, folate and vitamin B12, are involved in telomere biology and cellular aging. In particular, vitamin D is important for a range of vital cellular processes including cellular differentiation, proliferation and apoptosis. As a result of the multiple functions of vitamin D it has been speculated that vitamin D might play a role in telomere biology and genomic stability. Here we review existing knowledge about the link between telomere biology and cellular aging with a focus on the role of vitamin D. We searched the literature up to November 2014 for human studies, animal models and in vitro experiments that addressed this topic.