Combination of a 1,25-dihydroxyvitamin D3 analog and a bisphosphonate prevents experimental autoimmune encephalomyelitis and preserves bone

Molecular insights into the pathogenic impact of vitamin D deficiency in neurological disorders

Neurological disorders are the major cause of disability, leading to a decrease in quality of life by impairing cognitive, sensorimotor, and motor functioning. Several factors have been proposed in the pathogenesis of neurobehavioral changes, including nutritional, environmental, and genetic predisposition. Vitamin D (VD) is an environmental and nutritional factor that is widely distributed in the central nervous system's subcortical grey matter, neurons of the substantia nigra, hippocampus, thalamus, and hypothalamus. It is implicated in the regulation of several brain functions by preserving neuronal structures. It is a hormone rather than a nutritional vitamin that exerts a regulatory role in the pathophysiology of several neurological disorders, including Alzheimer's disease, Parkinson's disease, epilepsy, and multiple sclerosis. A growing body of epidemiological evidence suggests that VD is critical in neuronal development and shows neuroprotective effects by influencing the production and release of neurotrophins, antioxidants, immunomodulatory, regulation of intracellular calcium balance, and direct effect on the growth and differentiation of nerve cells. This review provides up-to-date and comprehensive information on vitamin D deficiency, risk factors, and clinical and preclinical evidence on its relationship with neurological disorders. Furthermore, this review provides mechanistic insight into the implications of vitamin D and its deficiency on the pathogenesis of neurological disorders. Thus, an understanding of the crucial role of vitamin D in the neurobiology of neurodegenerative disorders can assist in the better management of vitamin D-deficient individuals.

Hormones in experimental autoimmune encephalomyelitis (EAE) animal models

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS) in which activated immune cells attack the CNS and cause inflammation and demyelination. While the etiology of MS is still largely unknown, the interaction between hormones and the immune system plays a role in disease progression, but the mechanisms by which this occurs are incompletely understood. Several in vitro and in vivo experimental, but also clinical studies, have addressed the possible role of the endocrine system in susceptibility and severity of autoimmune diseases. Although there are several demyelinating models, experimental autoimmune encephalomyelitis (EAE) is the oldest and most commonly used model for MS in laboratory animals which enables researchers to translate their findings from EAE into human. Evidences imply that there is great heterogeneity in the susceptibility to the induction, the method of induction, and the response to various immunological or pharmacological interventions, which led to conflicting results on the role of specific hormones in the EAE model. In this review, we address the role of endocrine system in EAE model to provide a comprehensive view and a better understanding of the interactions between the endocrine and the immune systems in various models of EAE, to open up a ground for further detailed studies in this field by considering and comparing the results and models used in previous studies.

Serum 25-hydroxyvitamin D level and vitamin D receptor (VDR) polymorphisms in patients infected with Leishmania tropica: a case control study

Leishmania, an obligate intracellular parasite is eliminated by a strong Th-1 host response. As Vitamin D metabolism and its receptor activity are important factors in human native immune system against some microorganisms, we hypothesized that VDR gene polymorphisms and concentration of Vitamin D might have effect on incidence of cutaneous leishmaniasis. The aim of this study was to investigate the association between VDR gene polymorphism and/or the serum vitamin D level and leishmaniasis in the infected patients in comparison to the healthy individuals. In this case-control study, the BsmI, FokI and Taq1 polymorphisms in the VDR gene and serum levels of vitamin D were studied in Iranian infected with Leishmania tropica (n = 50) and healthy controls using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and Electrochemiluminescence methods respectively. Data were statistically analyzed using SPSS software, Chi square and ANOVA tests. The results of this study showed that despite the relatively higher frequency of BsmI-BB, FokI-FF and TaqI-Tt than Non BsmI-BB, Non FokI-FF and Non TaqI-Tt in the patients compared with the healthy individuals, the differences were not statistically significant (P > 0.05). Based on our findings, the relationship between the VDR polymorphism, the serum concentration of 25-hydroxyvitamin D and the susceptibility to Leishmania tropica infection, remains unclear requiring further in-depth studies. However, for better interpretation, it is necessary to consider factors such as the size of the sample examined and the other alleles of VDR, including ApaI.

Regulation of Immune Function by Vitamin D and Its Use in Diseases of Immunity

Evidence exists for a role for vitamin D and its active metabolites in modulating immune functions. In animal models, vitamin D deficiency is associated with a higher risk for autoimmunity in genetically predisposed subjects and increases in susceptibility to infections. In addition, high-dose vitamin D can improve immune health, prevent autoimmunity, and improve defense against infections. In humans, evidence exists on associations between vitamin D deficiency and impaired immune function, leading to autoimmunity in genetically predisposed people and increased risk for infections; data on therapeutic immune effects of vitamin D supplementation when vitamin D levels are already sufficient are lacking.

GENETICS FOR DIAGNOSTICS IN PREVENTIVE MEDICINE

The sequencing of first human genome followed by rapid development of technologies, that led to significant lowering of costs for genetic analyze and its fast performing, made possible a broad invention of genetic diagnostics methods into clinical practice. Contemporary methods of molecular genetics make possible to research on inherited factors on chromosome level with molecular cytogenetics methods, and on the level of local mutations with the use or polymeraze chain reaction, microchips and sequencing. Temps of the next generation sequencing methods provide the opportunity to predict soon inclusion in practice of the personalized medical analysis of large genetic data massive, that can be used for the disease outcome prediction, estimation of its course, and for the prescription and correction of pharmacotherapy. In this review, different (including novel) approaches to genetic diagnostics are explored for the rare as common diseases, their benefits and restrictions. 

Management of osteoporosis with calcitriol in elderly Chinese patients: a systematic review

Osteoporosis, a skeletal disorder characterized by a reduction in bone strength, is becoming a major public health problem in the People’s Republic of China, with a rapid increase observed among the population. Chinese guidelines particularly recommend use of active vitamin D in managing osteoporosis. 1,25-(OH)₂D₃ (calcitriol) is an active vitamin D metabolite. It plays a role in many biological processes, especially in bone metabolism and muscle function, and is mediated by vitamin D receptors. Osteoporosis in elderly men and women is characterized by uncoupled bone remodeling, which is induced by sex hormone deficiencies, somatopause, vitamin D deficiency, reduced synthesis of D hormone, and lack of receptors or receptor affinity for D hormone in target organs. Reviewed here are six randomized controlled trials on calcitriol monotherapy and five on calcitriol therapy combined with other antiosteoporotic agents. Evidence from these trials shows that calcitriol monotherapy can improve bone mineral density in elderly osteoporotic Chinese patients but may be insufficient for long-term treatment. Calcitriol can also decrease bone turnover markers and bring about significant improvements in muscle strength. Further, calcitriol in combination with other therapeutic bone agents was shown to be well tolerated and capable of additional bone-preserving effects compared with use of calcitriol alone in areas including bone mineral density, bone turnover markers, bone pain improvement, and fracture incidence. Hypercalcemia and hypercalciuria, the most common side effects of calcitriol therapy, were not documented in the trials reviewed, and might have been the result of the low dosages used. One study showed that treatment with calcitriol can improve quality of life in patients with osteoporosis, although not to the same extent as bisphosphonates.

Reduced serum concentrations of 25-hydroxy vitamin D in Egyptian patients with systemic lupus erythematosus: relation to disease activity

BACKGROUND

Recently, vitamin D deficiency has been implicated as a potential environmental factor triggering some autoimmune disorders, including systemic lupus erythematosus (SLE)). In addition, patients with SLE, especially those with increased disease activity, were suggested to have decreased vitamin D level, suggesting that vitamin D might play a role in regulating autoantibody production.

MATERIAL/METHODS

To assess 25 hydroxy vitamin D [25(OH)D] status in Egyptian patients with SLE and its relation to disease activity. Clinical evaluation and assay of serum 25(OH)D, total calcium, phosphorous, alkaline phosphatase (ALP) and parathyroid hormone (PTH) were done on 60 SLE patients in comparison to 60 matched-healthy subjects. Serum 25(OH)D levels <30 and 10 ng/ml were defined as vitamin D insufficiency and deficiency, respectively.

RESULTS

Serum 25(OH)D was significantly lower in patients than in controls (26.33 ± 12.05 vs. 42.66 ± 9.20 respectively, p < 0.0001), with 13.30% and 60% being deficient and insufficient, respectively. Serum 25(OH)D levels were lower with increased disease activity (p = 0.03) and frequency of photosensitivity(p = 0.02) and photoprotection (p = 0.002). Systemic lupus erythematosus disease activity index (SLEDAI) score (OR: 2.72, 95% CI: 1.42-5.18, P = 0.002), photosensitivity (OR: 3.6, 95% CI: 1.9-6.8, P < 0.01) and photoprotection (OR: 6.7, 95% CI: 2.9-8.8, P < 0.001) were significant predictors of 25(OH)D level among SLE cases.

CONCLUSIONS

Low vitamin D status is prevalent in Egyptian SLE patients despite plentiful exposure to sunlight throughout the year, and its level is negatively correlated to disease activity. Future studies looking at a potential role of vitamin D in the pathophysiology and treatment of SLE are warranted.

Sun exposure, vitamin D intake and progression to disability among veterans with progressive multiple sclerosis

BACKGROUND

Early life events have been suggested to influence multiple sclerosis (MS) susceptibility, and to potentially modulate its clinical course. We assessed vitamin D-related exposures from childhood to disease onset and their associations with MS progression.

METHODS

Among veterans in the Multiple Sclerosis Surveillance Registry, 219 reported having the progressive form and met the inclusion criteria. Participants reported their past sun exposure, vitamin D-related intake and age at disability milestones using the Patient-Determined Disease Steps (PDDS). The Cox proportional hazards model was used to examine the association between vitamin D-related exposures and time (years) to disability.

RESULTS

Low average sun exposure in the fall/winter before disease onset was associated with an increased risk of progressing to a PDDS score of 8 (hazard ratio, HR: 2.13, 95% confidence interval, CI: 1.20-3.78), whereas use of cod liver oil during childhood and adolescence was associated with a reduced risk (HR: 0.44, 95% CI: 0.20-0.96).

CONCLUSIONS

These results suggest that exposure to vitamin D before MS onset might slow disease-related neurodegeneration and thus delay progression to disability among patients with the progressive subtype.

Vitamin D as a T-cell modulator in multiple sclerosis

Vitamin D is a potent immune modulator, keeping the T-cell compartment in a more tolerogenic state. Multiple sclerosis (MS), a disease in which an autoreactive T-cell response contributes to inflammation in the central nervous system, has been associated with vitamin D deficiency. The effects of vitamin D on the immune system are believed to be an important driver of this association. In this chapter, we elaborate on vitamin D as a modulator of the T-cell response. This discussion will be placed in the perspective of MS as a T-cell-mediated disease and in the perspective of the numerous association studies on vitamin D deficiency and multiple health outcomes. We conclude that there is a firm experimental and epidemiological basis supporting the model of vitamin D as a physiological immune modulator, on which intervention studies assessing clinical and immunological outcome measures should be designed.

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

Vitamin D has received increased attention recently for its pleiotropic actions on many chronic diseases. The importance of vitamin D on the regulation of cells of the immune system has gained increased appreciation over the past decade with the discovery of the vitamin D receptor (VDR) and key vitamin D metabolizing enzymes expressed by cells of the immune system. Animal studies, early epidemiologic and clinical studies have supported a potential role for vitamin D in maintaining immune system balance. The hormonal form of vitamin D up-regulates anti-microbial peptides, namely cathelicidin, to enhance clearance of bacteria at various barrier sites and in immune cells. Vitamin D modulates the adaptive immune system by direct effects on T cell activation and on the phenotype and function of antigen-presenting cells (APCs), particularly of DCs. The purpose of this manuscript is to review the molecular and clinical evidence for vitamin D as a modulator of the innate and adaptive immune system.

Clinical implications of a possible role of vitamin D in multiple sclerosis

Hypovitaminosis D is currently one of the most studied environmental risk factors for multiple sclerosis (MS) and is potentially the most promising in terms of new clinical implications. These practical consequences, which could be applied to MS patients without further delay, constitute the main purpose of this review. Vitamin D is involved in a number of important general actions, which were not even suspected until quite recently. In particular, this vitamin could play an immunomodulatory role in the central nervous system. Many and varied arguments support a significant role for vitamin D in MS. In animal studies, vitamin D prevents and improves experimental autoimmune encephalomyelitis. Epidemiologically, latitude, past exposure to sun and the serum level of vitamin D influence the risk of MS, with, furthermore, significant links existing between these different factors. Clinically, most MS patients have low serum levels of vitamin D and are in a state of insufficiency or even deficiency compared to the international norm, which has been established on a metabolic basis. Large therapeutic trials using vitamin D are still lacking but the first results of phase I/II studies are promising. In the meantime, while awaiting the results of future therapeutic trials, it can no longer be ignored that many MS patients have a lack of vitamin D, which could be detected by a serum titration and corrected using an appropriate vitamin D supplementation in order to restore their serum level to within the normal range. From a purely medical point of view, vitamin D supplementation appears in this light to be unavoidable in order to improve the general state of these patients. Furthermore, it cannot currently be ruled out that this supplementation could also be neurologically beneficial.

Enhancement of 1,25-dihydroxyvitamin D3-mediated suppression of experimental autoimmune encephalomyelitis by calcitonin

The active form of vitamin D, 1alpha,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)], suppresses disease development in the experimental autoimmune encephalomyelitis (EAE) model of multiple sclerosis (MS). However, complete disease prevention only occurs with doses that dramatically elevate serum calcium levels, thus limiting the usefulness of 1,25(OH)(2)D(3) as a potential MS therapeutic agent. Because calcitonin (CT) is believed to be released by hypercalcemia and has been shown to be anti-inflammatory, we examined whether suppression of EAE by 1,25(OH)(2)D(3) could be mediated either in part or entirely by CT. Continuous administration of pharmacological doses of CT did not prevent EAE. However, a combination of CT and a subtherapeutic dose of 1,25(OH)(2)D(3) additively suppressed EAE without causing hypercalcemia. Moreover, CT decreased the dose of 1,25(OH)(2)D(3) required for disease suppression. Our results suggest that CT may be a significant factor but cannot account entirely for 1,25(OH)(2)D(3)-mediated suppression of EAE.

Impact of vitamin D receptor activity on experimental autoimmune prostatitis

Chronic non bacterial prostatitis is a chronic inflammatory syndrome. Its etiology and physiopathology are unclear and treatments are empirical and ineffective in most cases. Autoimmunity has been proposed as an etiology. In the present report, we investigated the impact of vitamin D receptor silencing, by use of VDR-KO NOD mice and the immune-modulating effect of the vitamin D3 analog TX527 on the development of Experimental Autoimmune Prostatitis in NOD mice. VDR-KO NOD mice developed a more aggressive form of autoimmune prostatitis characterized by a greater lymphoproliferative response against prostate antigen in vitro (6.92+/-4.77 vs. 2.47+/-0.41 21 days after disease induction, p<0.05) and higher levels of specific INFgamma secretion (471+/-6 vs. 386+/-5pg/ml, p<0.01). This was accompanied in vivo by more severe lesions and augmented mononuclear cell infiltration in the prostate gland. On the other hand, although analog-treated mice showed a significant reduction in the spleen T-cell specific proliferative response against prostate antigen in vitro, no effect on disease development was observed. We conclude that vitamin D receptor modulation holds the promise of interfering with autoimmune prostatitis. Introduction of more powerful analogs, or combinations with anti-T-cell reagents may represent therapeutic solutions for these group of patients.

Regulation of vitamin D homeostasis: implications for the immune system

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

The link between vitamin D deficiency and systemic lupus erythematosus

Vitamin D deficiency is highly prevalent and is increasingly thought to be an important risk factor in many diseases that have high morbidity and mortality, including lupus. Vitamin D is an immunomodulatory hormone with effects on T cells, B cells, and dendritic cells. Animal models of autoimmune disease and epidemiologic studies suggest a role for vitamin D as a modifiable environmental factor in autoimmune disease. Recommendations are available regarding screening for and repletion of vitamin D deficiency. More research is needed to understand the role of vitamin D as an immunomodulator and to determine the optimal range of serum 25-hydroxyvitamin D for musculoskeletal, cardiovascular, and immune health.

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.

Higher levels of 25-hydroxyvitamin D are associated with a lower incidence of multiple sclerosis only in women

INTRODUCTION

Multiple sclerosis (MS) is a chronic inflammatory disease with an as yet not fully understood etiological background. The geographical distribution of MS is striking with a prevalence that increases with latitude. For this reason, vitamin D deficiency is considered a possible pathogenic co-factor in MS.

MATERIALS AND METHODS

To study the role of the vitamin D metabolism in MS, blood samples were taken twice (summer and winter) from 103 patients with MS and 110 healthy controls. Serum concentrations of 25-hydroxyvitamin D (25(OH) D) and 1,25-dihydroxyvitamin D (1,25(OH)(2)D) were measured, and detailed information on disease characteristics and environmental factors that might influence the vitamin D metabolite levels was collected.

RESULTS

Mean serum 25(OH)D and 1,25(OH)(2)D concentrations were significantly higher in summer compared to winter in both patients and controls. Using logistic regression methods, we found that in women for every 10 nmol/L increase of serum 25(OH)D level the odds of MS was reduced by 19% (odds ratio 0.81; 95% confidence interval: 0.69-0.95), suggesting a "protective" effect of higher 25(OH)D serum levels. In addition, also restricted to women, a negative correlation was found between Expanded Disability Status Scale and 25(OH)D levels (r = -0.29, P = 0.020).

CONCLUSIONS

Our data suggest that higher circulating levels of 25(OH)D are associated with a lower incidence of MS and MS-related disability in women. This may imply clues to the pathogenesis of the sex difference in risk and to the nature of the environmental factors involved in MS.

Vitamin D and autoimmune disease

Vitamin D as a part of the endocrine system is an important component in the interaction between the kidney, bone, parathyroid hormone, and the intestine, which maintains extracellular calcium level within normal limits, in order to keep the vital physiologic process and skeletal integrity. Vitamin D is also associated with hypertension, muscular function, immunity, and ability to encounter infection, autoimmune disease, and cancer. The role of vitamin D in immunity is a feedback reaction of paracrine to eliminate inflammation or to influence CD4 T-cell differentiation and or to increase the function of T suppressor cell or combination between both. The active form of vitamin D produces and maintains self immunologic tolerance, some studies show that 1,25(OH)2D inhibits induction of disease in autoimmune encephalomyelitis, thyroiditis, type-1 diabetes mellitus, inflammatory bowel disease (IBD), systemic lupus erythematosus, and collagen-induced arthritis and Lyme arthritis.

Vitamin D and autoimmunity: new aetiological and therapeutic considerations

Vitamin D is frequently prescribed by rheumatologists to prevent and treat osteoporosis. Several observations have shown that vitamin D inhibits proinflammatory processes by suppressing the enhanced activity of immune cells that take part in the autoimmune reaction. Moreover, recent evidence strongly suggests that vitamin D supplementation may be therapeutically beneficial, particularly for Th1-mediated autoimmune disorders. Some reports imply that vitamin D may even be preventive in certain disorders such as multiple sclerosis and diabetes type 1. It seems that vitamin D has crossed the boundaries of calcium metabolism and has become a significant factor in a number of physiological functions, specifically as a biological inhibitor of inflammatory hyperactivity.

Vitamin D3and the immune system: maintaining the balance in health and disease

1,25-Dihydroxyvitamin D3(1,25(OH)2D3), the active form of vitamin D3, is a central player in Ca and bone metabolism. More recently, important immunomodulatory effects have been attributed to this hormone. By binding to its receptor, the vitamin D receptor, 1,25(OH)2D3regulates the expression of various genes and consequently affects the behaviour of different cell types within the immune system. 1,25(OH)2D3can potently inhibit pathogenic T cells and gives rise to elevated numbers of regulatory T cells via the induction of tolerogenic dendritic cells. These immunomodulatory activities of 1,25(OH)2D3have also been proven usefulin vivo: administration of 1,25(OH)2D3in several animal models can prevent or cure different autoimmune diseases and graft rejection. To overcome the dose-limiting side effects of 1,25(OH)2D3on Ca and bone, less calcaemic structural analogues (alone or in combination with synergistically acting drugs or bone-resorption inhibitors) have been successfully used in animal models. Furthermore, as 1,25(OH)2D3also contributes to host defence against infectious agents by the induction of antimicrobial responses, this molecule might provide a new strategy to deal with drug-resistant infections. According to the pleiotropic effects of 1,25(OH)2D3in the immune system, increasing epidemiological data underline the importance of adequate vitamin D intakes in reducing the risk of several autoimmune diseases and infections such as tuberculosis.

Novel insights in the immune function of the vitamin D system: synergism with interferon-beta

The 1,25(OH)(2)D(3) analog, TX527 (19-nor-14,20-bisepi-23-yne-1,25(OH)(2)D(3)), has an interesting dissociation profile between its potent immunomodulatory and its calcemic effects in vivo. The strong immunomodulatory potency of TX527 is reflected by its ability to attenuate experimental autoimmune encephalomyelitis (EAE), a murine model of multiple sclerosis (MS). At present most MS patients are being treated with systemic IFN-beta administration. The aim of this study was to investigate whether combining IFN-beta with TX527 could empower its EAE-protective effects. We evaluated also combinations with the standard immunosuppressant cyclosporin A (CsA). EAE was induced in SJL mice by PLP immunization, treatment was started 3 days before disease induction. The TX527+IFN-beta combination resulted in significant disease protection which was superior to the effect of both treatment separately. No disease amelioration, even aggravation, was obtained with the IFN-beta+CsA combination. By adding TX527 to the IFN-beta+CsA combination near complete protection from EAE was achieved (100% protection from paralysis, mean maximal score of 1.8+/-1.5, both p<0.05 versus controls and all individual treatments). From these data we conclude that adding TX527 to an IFN-beta and/or CsA treatment results in clear additional immunomodulatory effects in EAE prevention and is therefore a potentially interesting candidate to be considered in clinical intervention trials in MS.

Immunoregulation by 1,25-dihydroxyvitamin D3: basic concepts

1,25-Dihydroxyvitamin D(3) (1,25(OH)(2)D(3)), the biologically active metabolite of Vitamin D(3), not only regulates bone and calcium metabolism but also exerts other biological activities, including immunomodulation via the nuclear Vitamin D receptor expressed in antigen-presenting cells and activated T cells. This regulation is mediated through interference with nuclear transcription factors such as NF-AT and NF-kappaB or by direct interaction with Vitamin D responsive elements in the promoter regions of cytokine genes. Dendritic cells (DCs) are primary targets for the immunomodulatory activity of 1,25(OH)(2)D(3), as indicated by inhibited DC differentiation and maturation, leading to down-regulated expression of MHC-II, costimulatory molecules and IL-12. Moreover, 1,25(OH)(2)D(3) enhances IL-10 production and promotes DC apoptosis. Together, these effects of 1,25(OH)(2)D(3) inhibit DC-dependent T cell activation. Immunomodulation by 1,25(OH)(2)D(3) and its analogs in vivo has been demonstrated in different models of autoimmune diseases and transplantation. Moreover, combining analogs with other immunosuppressants leads to synergism in models of autoimmunity and transplantation. The availability of 1,25(OH)(2)D(3) analogs with immunomodulatory activity at non-hypercalcemic doses may allow exploitation of their immunomodulatory effects in a clinical setting of treatment of autoimmune diseases and prevention of allograft rejection.

Variation in the vitamin D receptor gene is associated with multiple sclerosis in an Australian population

Multiple Sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS) resulting in accumulating neurological disability. The disorder is more prevalent at higher latitudes. To investigate VDR gene variation using three intragenic restriction fragment length polymorphisms (Apa I, Taq I and Fok I) in an Australian MS case-control population. One hundred and four Australian MS patients were studied with patients classified clinically as Relapsing Remitting MS (RR-MS), Secondary Progressive MS (SP-MS) or Primary Progressive MS (PP-MS). Also, 104 age-, sex-, and ethnicity-matched controls were investigated as a comparative group. Our results show a significant difference of genotype distribution frequency between the case and control groups for the functional exon 9 VDR marker Taq I (p(Gen) = 0.016) and interestingly, a stronger difference for the allelic frequency (p(All) = 0.0072). The Apa I alleles were also found to be associated with MS (p(All) = 0.04) but genotype frequencies were not significantly different from controls (p(Gen) = 0.1). The Taq and Apa variants are in very strong and significant linkage disequilibrium (D' = 0.96, P < 0.0001). The genotypic associations are strongest for the progressive forms of MS (SP-MS and PP-MS). Our results support a role for the VDR gene increasing the risk of developing multiple sclerosis, particularly the progressive clinical subtypes of MS.

Hypercalcemia produced by parathyroid hormone suppresses experimental autoimmune encephalomyelitis in female but not male mice

Besides its role in regulating serum levels of calcium and phosphorus, 1alpha, 25-dihydroxyvitamin D3 (1,25-(OH)2D3) has potent effects on the immune system and suppresses disease in several animal models of autoimmune disorders including experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis. While the amount of 1,25-(OH)2D3 needed to prevent EAE is dependent on the gender of the mouse and amount of calcium available in the diet, the minimum levels of 1,25-(OH)2D3 sufficient to prevent disease cause hypercalcemia. To test if hypercalcemia independent of high levels of 1,25-(OH)2D3 can suppress EAE, we used a 25-hydroxyvitamin D3-1alpha-hydroxylase (1alpha-hydroxylase) knockout mouse strain. Because these 1alpha-hydroxylase knockout mice lack the parathyroid hormone (PTH)-regulated enzyme that synthesizes 1,25-(OH)2D3, hypercalcemia from increased bone turnover was created by continuous administration of PTH without changing the circulating levels of 1,25-(OH)2D3. This PTH-mediated hypercalcemia generated after EAE induction prevented disease in female mice but not male mice. When hypercalcemia was prevented by diet manipulation, PTH administration no longer prevented EAE. We conclude that hypercalcemia is able to prevent EAE after disease induction in female mice.

Multiple sclerosis and vitamin D: an update

MS is a chronic, immune-mediated inflammatory and neurodegenerative disease of the central nervous system (CNS), with an etiology that is not yet fully understood. The prevalence of MS is highest where environmental supplies of vitamin D are lowest. It is well recognized that the active hormonal form of vitamin D, 1,25-dihydroxyvitamin D (1,25-(OH)(2)D), is a natural immunoregulator with anti-inflammatory action. The mechanism by which vitamin D nutrition is thought to influence MS involves paracrine or autocrine metabolism of 25OHD by cells expressing the enzyme 1 alpha-OHase in peripheral tissues involved in immune and neural function. Administration of the active metabolite 1,25-(OH)(2)D in mice and rats with experimental allergic encephalomyelitis (EAE, an animal model of MS) not only prevented, but also reduced disease activity. 1,25-(OH)(2)D alters dendritic cell and T-cell function and regulates macrophages in EAE. Interestingly, 1,25-(OH)(2)D is thought to be operating on CNS constituent cells as well. Vitamin D deficiency is caused by insufficient sunlight exposure or low dietary vitamin D(3) intake. Subtle defects in vitamin D metabolism, including genetic polymorphisms related to vitamin D, might possibly be involved as well. Optimal 25OHD serum concentrations, throughout the year, may be beneficial for patients with MS, both to obtain immune-mediated suppression of disease activity, and also to decrease disease-related complications, including increased bone resorption, fractures, and muscle weakness.

Characterization of five 19-nor-analogs of 1alpha,25(OH)2-Vitamin D3 with 20-cyclopropyl-modified side-chains: implications for ligand binding and calcemic properties

The steroid hormone 1alpha,25(OH)(2)-Vitamin D(3) [1alpha,25(OH)(2)D(3)] exerts a wide variety of biological actions through one or more receptors/binding proteins. The nuclear Vitamin D receptor (VDR) when bound to its natural ligand, 1alpha,25(OH)(2)D(3), can stimulate transcription of a wide variety of genes. The synthesis of 1alpha,25(OH)(2)D(3) analogs allows the study of structure-function relationships between ligand and the VDR. 1alpha,25(OH)(2)D(3) is a conformationally flexible molecule; specifically the side-chain of the hormone can display a large variety of shapes for its receptor. Here, we describe and analyze the properties of 10 1alpha,25(OH)(2)D(3) analogs modified at the side-chain of which five lack carbon-19 (19-nor) but have a novel 20-cyclopropyl functionality. Analog NG [20,21-methylene-23-yne-26,27-F(6)-19-nor-1alpha,25(OH)(2)D(3)] possesses a respectable binding affinity for the VDR and exhibits a high transcriptional activity (EC(50) approximately 10pM), while retaining low induction of hypercalcemia in vivo in the mouse, making it a primary candidate for further analyses of its anti-proliferative and/or cell differentiating properties.

Vitamin D deficiency in early life accelerates Type 1 diabetes in non-obese diabetic mice

AIMS/HYPOTHESIS

1,25-dihydroxyvitamin D(3), the active form of vitamin D, prevents Type 1 diabetes in non-obese diabetic (NOD) mice. Epidemiological data show a threefold increase in human Type 1 diabetes when vitamin D deficiency was present in the first months of life. To evaluate whether a similar dietary deficiency affects diabetes incidence in NOD mice, we generated NOD mice with vitamin D deficiency in early life.

METHODS

Breeding pairs of NOD mice, as well as their offspring (test mice), were kept in surroundings devoid of ultraviolet light and were fed a vitamin D-depleted diet for 100 days. Mice were followed for 250 days.

RESULTS

At 250 days, 35% (12/35) male and 66% (22/33) female vitamin D-deficient mice were diabetic compared to 15% (6/40, p=0.05) and 45% (13/29, p<0.01) of the control mice. At 100 days no difference in insulitis was seen, but more vitamin D-deficient mice were glucose intolerant. Higher IL1 expression was detected in islets of vitamin D-deficient mice and their peritoneal macrophages had an aberrant cytokine profile (low IL1 and IL6, high IL15). Thymus and lymph nodes of vitamin D-deficient mice contained less CD4(+)CD62L(+) cells.

CONCLUSION/INTERPRETATION

Vitamin D status increases the expression of Type 1 diabetes in NOD mice. Our data in NOD mice, as well as human epidemiological data, point to the importance of preventing vitamin D deficiency in early childhood. Controlling this dietary factor could be an easy and safe way to reduce the incidence of Type 1 diabetes in subjects who are genetically at risk.