Contribution of vitamin D insufficiency to the pathogenesis of multiple sclerosis

An ultra-sensitive and high-throughput trapping-micro-LC-MS method for quantification of circulating vitamin D metabolites and application in multiple sclerosis patients

Quantitative analysis of the biologically-active metabolites of vitamin D (VitD), which are crucial in regulating various physiological and pathological processes, is important for clinical investigations. Liquid chromatography-tandem mass spectrometry (LC-MS) has been widely used for this purpose but existing LC-MS methods face challenges in achieving highly sensitive and accurate quantification of low-abundance VitD metabolites while maintaining high throughput and robustness. Here we developed a novel pipeline that combines a trapping-micro-LC-(T-µLC) with narrow-window-isolation selected-reaction monitoring MS(NWI-SRM) for ultra-sensitive, robust and high-throughput quantification of VitD metabolites in serum samples after derivatization. The selective-trapping and delivery approach efficiently removes matrix components, enabling high-capacity sample loading and enhancing sensitivity, throughput, and robustness. The NWI-SRM further improves the sensitivity by providing high selectivity. The lower limits of quantification (LOQs) achieved were markedly lower than any existing LC-MS methods: 1.0 pg/mL for 1,25(OH)2D3, 5.0 pg/mL for 24,25(OH)2D3, 30 pg/mL for both 25(OH)D2 and 25(OH)D3, all within a 9-min cycle. The method is applied to quantify VitD metabolites from 218 patients with multiple sclerosis. This study revealed negative correlations(r=- 0.44 to - 0.51) between the levels of 25(OH)D2 and all the three D3 metabolites in multiple sclerosis patients.

Changes in serum cytokine profile and deficit severity in patients with relapsing-remitting multiple sclerosis

INTRODUCTION

In experimental autoimmune encephalomyelitis, neurological deficit correlates with axonal loss and the CD8+ T cells are a likely mediator of axonal damage. In relapsing-remitting multiple sclerosis, there is a correlation of the immune inflammatory activity in the lesion foci with the axon transection.

Vitamin D-An Effective Antioxidant in an Animal Model of Progressive Multiple Sclerosis

Vitamin D (VD) is the most discussed antioxidant supplement for multiple sclerosis (MS) patients and many studies suggest correlations between a low VD serum level and onset and progression of the disease. While many studies in animals as well as clinical studies focused on the role of VD in the relapsing-remitting MS, knowledge is rather sparse for the progressive phase of the disease and the development of cortical pathology. In this study, we used our established rat model of cortical inflammatory demyelination, resembling features seen in late progressive MS, to address the question about whether VD could have positive effects on reducing cortical pathology, oxidative stress, and neurofilament light chain (NfL) serum levels. For this purpose, we used male Dark Agouti (DA) rats, with one group being supplemented with VD (400 IE per week; VD+) from the weaning on at age three weeks; the other group received standard rodent food. The rat brains were assessed using immunohistochemical markers against demyelination, microglial activation, apoptosis, neurons, neurofilament, and reactive astrocytes. To evaluate the effect of VD on oxidative stress and the antioxidant capacity, we used two different oxidized lipid markers (anti- Cu++ and HOCl oxidized LDL antibodies) along with colorimetric methods for protective polyphenols (PP) and total antioxidative capacity (TAC). NfL serum levels of VD+ and VD- animals were analyzed by fourth generation single-molecule array (SIMOA) analysis. We found significant differences between the VD+ and VD- animals both in histopathology as well as in all serum markers. Myelin loss and microglial activation is lower in VD+ animals and the number of apoptotic cells is significantly reduced with a higher neuronal survival. VD+ animals show significantly lower NfL serum levels, a higher TAC, and more PP. Additionally, there is a significant reduction of oxidized lipid markers in animals under VD supplementation. Our data thus show a positive effect of VD on cellular features of cortical pathology in our animal model, presumably due to protection against reactive oxygen species. In this study, VD enhanced remyelination and prevented neuroaxonal and oxidative damage, such as demyelination and neurodegeneration. However, more studies on VD dose relations are required to establish an optimal response while avoiding overdosing.

Vitamin D status and latitude predict brain lesions in adrenoleukodystrophy

Objectives

Approximately 40% of boys with X-linked adrenoleukodystrophy (ALD) develop inflammatory demyelinating brain lesions (cerebral ALD, cALD) and are at risk for death or severe disability. Risk factors for cALD are poorly understood. Our objective was to evaluate whether vitamin D status, which influences immune function, is associated with risk for cALD.

Methods

We used two independent cohorts to assess whether low vitamin D status is correlated with cALD. We used complementary proxies for vitamin D status: plasma 25-hydroxyvitamin D levels and latitude. In our first cohort, we measured 25-hydroxyvitamin D in biobanked plasma samples from ALD boys with initially normal brain MRIs followed at two expert centers. In a second cohort, we measured latitude (using home ZIP code) among ALD boys identified in a national administrative database (PHIS) covering 51 US pediatric hospitals. We used logistic regression models to estimate the odds of developing cALD in each cohort.

Results

In the first cohort, we identified 20 ALD boys with a total of 53 plasma sample timepoints who met inclusion criteria; 50% (n = 10) subsequently developed cALD. Average 25-hydroxyvitamin D levels were lower among boys who developed cALD than those who did not (median 28.9 vs 36.6 ng/ml); p = 0.019. For each 10 ng/mL decrease in 25-hydroxyvitamin D, the odds ratio for developing cALD was 6.94; p = 0.044. In the second cohort, we identified 230 ALD boys across 28 states; 57% of boys (n = 132) developed cALD. Each 2° increase in latitude conferred an odds ratio of 1.17 (95% confidence interval, 1.01, 1.35); p = 0.036 for developing cALD.

Conclusions

Using independent cohorts, we found that ALD boys with lower pre-morbid plasma levels of 25-hydroxyvitamin D, or more northerly latitude of residence, were more likely to develop cALD. These findings offer complementary lines of evidence that vitamin D and/or ultraviolet light exposure influence cALD risk.

A Phase 1 Study of Oral Vitamin D3in Boys and Young Men With X-Linked Adrenoleukodystrophy

Background and Objectives

There are no therapies for preventing cerebral demyelination in X-linked adrenoleukodystrophy (ALD). Higher plasma vitamin D levels have been linked to lower risk of inflammatory brain lesions. We assessed the safety and pharmacokinetics of oral vitamin D dosing regimens in boys and young men with ALD.

Methods

In this open-label, multicenter, phase 1 study, we recruited boys and young men with ALD without brain lesions to a 12-month study of daily oral vitamin D3supplementation. Our primary outcome was attainment of plasma 25-hydroxyvitamin D levels in target range (40–80 ng/mL) at 6 and 12 months. Secondary outcomes included safety and glutathione levels in the brain, measured with magnetic resonance spectroscopy, and blood, measured via mass spectrometry. Participants were initially assigned to a fixed dosing regimen starting at 2,000 IU daily, regardless of weight. After a midstudy safety assessment, we modified the dosing regimen, so all subsequent participants were assigned to a weight-stratified dosing regimen starting as low as 1,000 IU daily.

Results

Between October 2016 and June 2019, we enrolled 21 participants (n = 12, fixed-dose regimen; n = 9, weight-stratified regimen) with a median age of 6.7 years (range: 1.9–22 years) and median weight of 20 kg (range: 11.7–85.5 kg). The number of participants achieving target vitamin D levels was similar in both groups at 6 months (fixed dose: 92%; weight stratified: 78%) and 12 months (fixed dose: 67%; weight stratified: 67%). Among the 12 participants in the fixed-dose regimen, half had asymptomatic elevations in either urine calcium:creatinine or plasma 25-hydroxyvitamin D; no laboratory deviations occurred with the weight-stratified regimen. Glutathione levels in the brain, but not the blood, increased significantly between baseline and 12 months.

Discussion

Our vitamin D dosing regimens were well tolerated and achieved target 25-hydroxyvitamin D levels in most participants. Brain glutathione levels warrant further study as a biomarker for vitamin D and ALD.

Classification of Evidence

This study provides Class IV evidence that fixed or weight-stratified vitamin D supplementation achieved target levels of 25-hydroxyvitamin D in boys and young men with X-ALD without brain lesions.

Therapeutic Role of Vitamin D in Multiple Sclerosis: An Essentially Contested Concept

Multiple sclerosis (MS) is an immune-mediated demyelinating disease of the nervous system with incredibly intricate etiopathogenesis involving numerous genetic, epigenetic, and environmental risk factors. Major environmental risk factors include ultraviolet (UV) radiation, vitamin D, Epstein-Barr virus (EBV) infection, smoking, and high body mass index (BMI). Vitamin D, in particular, can be viewed as one piece of this puzzle, with various tabs and pockets, occupying a sequential site. In this article, we have briefly discussed the neuroimmunology of MS and the role of vitamin D in regulating immune responses. Various observational studies and clinical trials were reviewed and discussed according to stages of disease activity and course of the disease. The data reviewed in this article implied that serum vitamin D levels greatly influence the risk of developing MS and disease activity. Long-term follow-up studies indicated that low serum vitamin D levels correlate with worse disability outcomes. Since clinical trials did not provide significant evidence, the role of vitamin D in controlling disease activity remains unresolved. Larger clinical trials are needed to support the findings of observational studies and provide significant evidence in favour of vitamin D. 

Effect of Seasonal Variation on Relapse Rate in Patients With Relapsing-Remitting Multiple Sclerosis in Saudi Arabia

Multiple sclerosis (MS) is becoming a global subject of study in which some demographic variations are thought to be correlated with its activity. Relapsing-remitting multiple sclerosis (RRMS) is the most common demyelinating disorder, characterized by periods of exacerbating attacks, followed by partial or complete remission. Several factors might play a role in disease progression and relapse frequency, such as vitamin D, ultraviolet B radiation, estrogen levels, smoking, obesity, and unhealthy lifestyles. In this study, we identified the relationship between seasonal variation and relapse rate and correlated the latter with sex, age, and vitamin D levels in patients with RRMS in Jeddah, Saudi Arabia. We retrospectively collected data from 182 RRMS patients between 2016 and 2021. A total of 219 relapses were documented in 106 patients (58.2 %). The relapse per patient ratio showed a sinusoidal pattern, peaking in January at a rate of 0.49 and troughed in June at a rate of 0.18. There was no difference in relapse rates between men and women (p =0.280). There was a significant negative correlation between vitamin D levels and relapse rate (r = −0.312, p =0.024). Therefore, the relapse rate was higher during the winter and was correlated with low vitamin D levels. However, relapses are likely multifactorial, and more population-based studies are needed to understand the role of environmental variables in MS exacerbation. A better understanding of this relationship will allow for improved treatment and possibly better prevention of relapse.

MicroRNA-22 Level in Patients with Multiple Sclerosis and Its Relationship with Vitamin D and Vitamin D Receptor Levels

INTRODUCTION

Multiple sclerosis (MS) is known to be a multifactorial disorder. Numerous observational studies have suggested the implication of multiple genetic and environmental factors in the pathogenesis of MS. The aim of this work was to evaluate expression of the microRNA-22 (miRNA-22) level, in relation to vitamin D (VD) and VD receptor (VDR) levels in patients with MS during remission state.

METHODS

This case-control study was conducted in 50 patients with clinically definite MS and 50 age- and sex-matched healthy controls. miRNA-22 expression was assessed in both MS patients and controls using quantitative RT-PCR. The serum level of VD and VDR was assessed in both MS patients and controls using ELISA techniques.

RESULTS

The miRNA-22 level was significantly downregulated in MS patients in comparison to controls (p value <0.001). MS patients had also significantly lower VD and VDR levels in comparison to controls (p value <0.001 and <0.001, respectively). Patients with secondary progressive MS (SPMS) have a significantly higher miRNA-22 level than patients with relapsing remitting MS (RRMS) (p value = 0.042). There was a statistically significant positive correlation between the miRNA-22 level and EDSS (p value = 0.033). There was also a statistically significant positive correlation between the miRNA-22 level and VDR level (p value = 0.002).

CONCLUSION

The miRNA-22 level was significantly downregulated in MS patients, but it had a positive correlation with disability status. Patients with SPMS have a significantly higher miRNA-22 level than patients with RRMS. VD and VDR levels were significantly lower in MS patients than controls. The miRNA-22 level was positively correlated with the VDR level.

Estimating prevalence of human traits among populations from polygenic risk scores

The genetic basis of phenotypic variation across populations has not been well explained for most traits. Several factors may cause disparities, from variation in environments to divergent population genetic structure. We hypothesized that a population-level polygenic risk score (PRS) can explain phenotypic variation among geographic populations based solely on risk allele frequencies. We applied a population-specific PRS (psPRS) to 26 populations from the 1000 Genomes to four phenotypes: lactase persistence (LP), melanoma, multiple sclerosis (MS) and height. Our models assumed additive genetic architecture among the polymorphisms in the psPRSs, as is convention. Linear psPRSs explained a significant proportion of trait variance ranging from 0.32 for height in men to 0.88 for melanoma. The best models for LP and height were linear, while those for melanoma and MS were nonlinear. As not all variants in a PRS may confer similar, or even any, risk among diverse populations, we also filtered out SNPs to assess whether variance explained was improved using psPRSs with fewer SNPs. Variance explained usually improved with fewer SNPs in the psPRS and was as high as 0.99 for height in men using only 548 of the initial 4208 SNPs. That reducing SNPs improves psPRSs performance may indicate that missing heritability is partially due to complex architecture that does not mandate additivity, undiscovered variants or spurious associations in the databases. We demonstrated that PRS-based analyses can be used across diverse populations and phenotypes for population prediction and that these comparisons can identify the universal risk variants.

Vitamin D status, proinflammatory cytokines and bone mineral density in Mexican people with multiple sclerosis

BACKGROUND

Vitamin D (VD) has been classically associated with calcium homeostasis and bone mineral density since it has a key role on mineralization and resorption. Immunomodulatory effects have been attributable to VD; low concentrations of VD have been associated with elevation of inflammatory markers. Inflammatory autoimmune diseases, such as multiple sclerosis (MS), a chronic neurodegenerative suffering, whose etiology is still unknown, is directly related to an increase in pro-inflammatory cytokines such as interleukin 17 and interleukin 1β who play an important role in this physiopathology. Nowadays, even though additional studies have linked MS's clinical signs with low VD concentration, there is scarce information of this association in people from regions with sufficient sun exposure. The aim of this study was to evaluate serum VD and cytokine concentrations, and bone density, in Mexican people with MS.

METHODS

Vitamin D (25OHD), interleukin 1β, interleukin 6 and interleukin 17 concentrations of twenty-five volunteers with MS were determined by enzyme-linked immunosorbent assay. Bone mineral density and body composition assessment was performed by dual energy X-Ray absorptiometry.

RESULTS

A mean concentration of 17.3 ± 4.6 ng/ml of 25OHD was obtained, in a range of 5.15 to 25.71 ng/ml; when international advisory bodies thresholds were applied 76% of the participants exhibited some degree of VD inadequacy. Pro-inflammatory markers were detectable among the participants: interleukin 1β in 100%, interleukin 6 in 64%, whereas interleukin 17 was found in 24% of the volunteers. Bone mineral density below the expected for the age was found in 8% of the participants, with lumbar spine as the most affected anatomic region. Non-significant correlations were found between VD and bone mineral density (Z-score) or pro-inflammatory markers.

CONCLUSION

Although non-significant correlations were found between VD and bone mineral density or cytokines, it is important to highlight that an important percentage of our participants exhibited some degree of VD inadequacy, an unknown fact for them, since these are not included in routine clinical evaluations. The low concentrations of VD among this sample regardless of annual UVB sun exposure may suggest the involvement of endogenous and not environmental factors. Further works are needed in order to deepen the physiological causes and effects of VD deficiency in people with MS.

Analysis of inflammasomes and CYP27B1 genes in cuprizone demyelinated C57BL/6 mice and evaluation of Th1 and Th2 patterns after oral administration of Lactobacillus casei strain T2 (IBRC-M10783)

Multiple sclerosis is characterized by the destruction of myelin in the CNS. Various factors including genetics, epigenetics, and environmental factors are involved in the development of the disease. There is evidence that changes in the gut microbiome profile are associated with immune-related diseases such as MS. Probiotics can alter the composition of the gut microbiota on the mucosal surfaces by differentiating naive T cells into Th1, Th2, Th17, and Treg cells. Female C57BL/6 mice were divided into 6 groups (n = 7): Normal group, cuprizone group (gavage of cuprizone for 4 weeks), Probiotic group (gavage of probiotic for 4 weeks), Treatment1 group (Probiotic for 4 weeks and then cuprizone for 4 weeks), treatment2 group (cuprizone for 4 weeks and then probiotic for 4 weeks) and treatment3 group (cuprizone for 4 weeks and then probiotic for 4 weeks with vitamin D3). Then the expression of NLRP-1, NLRP-3, AIM2, and CYP27B1 genes were evaluated using Real-Time PCR, and serum levels of IFN-γ and IL-4 were also measured by ELISA.The results showed a significant decrease in the expression of inflammasome and CYP27B1 genes in the probiotic-treated groups compared to the cuprizone group. Also, the comparison between probiotic-treated groups and cuprizone group showed a significant decrease in the amount of IFN-γ and IL-4. Due to reduced expression of the inflammasome genes as well as the decrease in IFN-γ levels as an inflammatory cytokine, it appears that L. casei may be effective in the healing process of demyelinated mice.

Search for viral agents in cerebrospinal fluid in patients with multiple sclerosis using real-time PCR and metagenomics

Multiple sclerosis (MS) is a chronic, immune-mediated demyelinating disease of the central nervous system of unclear etiology, but there is some evidence that viral infections could be responsible for triggering autoimmune mechanisms against myelin. We searched for viral RNA and DNA in cerebrospinal fluid (CSF) of 34 MS patients and 13 controls using RT-PCR/PCR against common neurotropic viruses. In addition, shotgun DNA- and RNA-based metagenomics were done in 13 MS patients and 4 controls. Specific quantitative real-time RT-PCR/PCR testing revealed the presence of viral nucleic acid in seven (20.59%) MS patients and in one (7.69%) control patient. In MS patients the most frequently detected was human herpesvirus type 6 (HHV-6; 3 cases; 8.82%); followed by Epstein-Barr virus (EBV; 2 cases; 5.88%), varicella zoster virus (VZV; 1 case; 2.94%) and Enterovirus (EV; 1 case; 2.94%). The single identified virus among controls was EBV (7.69%). DNA and RNA metagenomic assays did not identify any known eukaryotic viruses even though three of the analyzed samples were low-level positive by specific quantitative real-time PCR. In conclusion, we detected the presence of Herpesviridae and occasionally Enteroviridae in CSF from patients with MS but their prevalence was not significantly higher than among controls. Metagenomic analysis seems to be less sensitive than real-time RT-PCR/PCR and it did not detect any potential viral pathogens.

Skin Phototype Could Be a Risk Factor for Multiple Sclerosis

Environmental and genetic factors are assumed to be necessary for the development of multiple sclerosis (MS), however its interactions are still unclear. For this reason here, we have not only analyzed the impact on increased risk of MS of the best known factors (HLA-DRB1*15:01 allele, sun exposure, vitamin D levels, smoking habit), but we have included another factor (skin phototype) that has not been analyzed in depth until now. This study included 149 MS patients and 147 controls. A multivariate logistic regression (LR) model was carried out to determine the impact of each of the factors on the increased risk of MS. Receiver Operating Characteristics (ROC) analysis was performed to evaluate predictive value of the models. Our multifactorial LR model of susceptibility showed that females with light brown skin (LBS), smokers and who had HLA-DRB1*15:01 allele had a higher MS risk (LBS: OR = 5.90, IC95% = 2.39–15.45; smoker: OR = 4.52, IC95% = 2.69–7.72; presence of HLA-DRB1*15:01: OR = 2.39, IC95% = 1.30–4.50; female: OR = 1.88, IC95% = 1.08–3.30). This model had an acceptable discriminant value with an Area Under a Curve AUC of 0.76 (0.69–0.82). Our study indicates that MS risk is determined by complex interactions between sex, environmental factors, and genotype where the milieu could provide the enabling proinflammatory environment that drives an autoimmune attack against myelin by self-reactive lymphocytes.

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

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

Vitamin D increases remyelination by promoting oligodendrocyte lineage differentiation

INTRODUCTION

Several experimental studies have suggested the potential remyelinating effects of vitamin D (VitD) supplements regardless of the presence of VitD deficiency. This study aims to analyze neurogenesis in a model of toxic demyelination in order to evaluate the effects of VitD on demyelination and remyelination.

MATERIAL AND METHODS

We used 24 male Wistar rats that had received surgical lesions to the corpus callosum and were injected with lysolecithin. Rats were divided into three groups: Group 1 included eight rats with lesions to the corpus callosum but not lysolecithin injections (sham group), group 2 included eight rats with lesions to the corpus callosum that were injected with lysolecithin (lysolecithin group), and group 3 included eight rats with lesions that were injected with lysolecithin and received VitD (VitD group). We analyzed neurogenesis both in the subventricular zone and at the lesion site.

RESULTS

Administration of VitD promotes the proliferation and differentiation of neural stem cells in the subventricular zone and the migration of these cells to the lesion site in the corpus callosum; these cells subsequently differentiate into oligodendrocyte lineage cells and produce myelin basic protein. This phenomenon was not caused by microglial activation, which was less marked in rats receiving VitD. Megalin expression did not increase at the lesion site, which suggests that VitD is internalized by other mechanisms.

CONCLUSION

Our results support the hypothesis that regardless of the presence of VitD deficiency, treatment with VitD may contribute to remyelination by promoting the proliferation of oligodendrocyte precursor cells.

Association between vitamin D receptor (VDR) polymorphisms and the risk of multiple sclerosis (MS): an updated meta-analysis

Background

The association between the Vitamin D Receptor (VDR) gene polymorphism and the risk of Multiple sclerosis (MS) has been evaluated in several researches. However, the findings were inconsistent and inconclusive. Therefore, we set out a meta-analysis of all eligible published case-control studies to obtain an exact evaluation of the association between VDR gene polymorphisms and MS.

Method

All relevant studies reporting the association between the VDR gene FokI (rs2228570), or/and TaqI (rs731236) or/and BsmI (rs1544410) or/and ApaI (rs7975232) polymorphisms and susceptibility to MS published up to May, 2019 were identified by comprehensive systematic search in the electronic database of web of science, Scopus, and PubMed. After that, the strength of association between VDR gene polymorphisms and susceptibility to MS was evaluated by odds ratio (OR) and 95% confidence interval (CI).

Results

A total of 30 case–control studies were included in the meta-analysis. The overall results suggested a significant association between TaqI polymorphism and MS risk under heterozygote genetic model (OR = 1.27, 95%CI = 1.01–1.59, random effect). Moreover, the pooled results of subgroup analysis declined presence of significant association under all defined genetic model. In subgroup analysis, BsmI polymorphisms was associated with increased risk of MS under recessive model in Asian populations. On the other hand, ApaI polymorphism was associated with decreased risk of MS under recessive and aa vs. AA model in Asian populations.

Conclusion

This meta-analysis suggested a significant association between TaqI polymorphism and MS susceptibility. Furthermore, BsmI polymorphism was associated with increased risk of MS in Asian populations. In contrast, ApaI polymorphism was associated with decreased risk of MS in Asian populations. Future large-scale studies on gene–environment and gene–gene interactions are required to estimate risk factors and assist early diagnosis of patients at high risk for MS.

Mediterranean diet: The role of long-chain ω-3 fatty acids in fish; polyphenols in fruits, vegetables, cereals, coffee, tea, cacao and wine; probiotics and vitamins in prevention of stroke, age-related cognitive decline, and Alzheimer disease

The mechanisms of action of the dietary components of the Mediterranean diet are reviewed in prevention of cardiovascular disease, stroke, age-associated cognitive decline and Alzheimer disease. A companion article provides a comprehensive review of extra-virgin olive oil. The benefits of consumption of long-chain ω-3 fatty acids are described. Fresh fish provides eicosapentaenoic acid while α-linolenic acid is found in canola and soybean oils, purslane and nuts. These ω-3 fatty acids interact metabolically with ω-6 fatty acids mainly linoleic acid from corn oil, sunflower oil and peanut oil. Diets rich in ω-6 fatty acids inhibit the formation of healthier ω-3 fatty acids. The deleterious effects on lipid metabolism of excessive intake of carbohydrates, in particular high-fructose corn syrup and artificial sweeteners, are explained. The critical role of the ω-3 fatty acid docosahexaenoic acid in the developing and aging brain and in Alzheimer disease is addressed. Nutritional epidemiology studies, prospective population-based surveys, and clinical trials confirm the salutary effects of fish consumption on prevention of coronary artery disease, stroke and dementia. Recent recommendations on fish consumption by pregnant women and potential mercury toxicity are reviewed. The polyphenols and flavonoids of plant origin play a critical role in the Mediterranean diet, because of their antioxidant and anti-inflammatory properties of benefit in type-2 diabetes mellitus, cardiovascular disease, stroke and cancer prevention. Polyphenols from fruits and vegetables modulate tau hyperphosphorylation and beta amyloid aggregation in animal models of Alzheimer disease. From the public health viewpoint worldwide the daily consumption of fruits and vegetables has become the main tool for prevention of cardiovascular disease and stroke. We review the important dietary role of cereal grains in prevention of coronary disease and stroke. Polyphenols from grapes, wine and alcoholic beverages are discussed, in particular their effects on coagulation. The mechanisms of action of probiotics and vitamins are also included.

Multiple sclerosis: disease modifying therapy and the human leukocyte antigen

OBJECTIVE

To investigate the potential relationship between the human leukocyte antigen (HLA) type (class I and II) and the response to several disease-modifying therapies (DMTs) in patients with multiple sclerosis (MS).

METHODS

We analyzed clinical data of 87 patients with MS at the beginning and end of each type of DMT including the disease duration, Expanded Disability Status Scale and Multiple Sclerosis Severity Score (MSSS). Genotyping of HLA-DRB1, HLA-DPB1, HLA-DQB1, HLA-A, HLA-B and HLA-C alleles were identified using high-resolution techniques. Statistical correlation between the HLA type and response to DMTs was done using the initial and final MSSS.

RESULTS

Statistical relationships (p < 0.05) were found for only 15 of 245 alleles tested. There was a reduction in the MSSS for patients treated with corticosteroids (DRB1*15:01, DPB1*04:01, DQB1*02:01 and DQB1*03:01), azathioprine (DRB1*03:01, DPB1*04:01, DQB1*03:02, DQB1*06:02, HLA-C*07:02), interferon β-1a 22 mcg (DRB1*11:04, DQB1*03:01 and DQB1*03:02), interferon β-1a 30 mcg (DPB1*02:01, HLA-C*05:01) and interferon β-1b (DQB1*02:01).

CONCLUSION

These findings suggest a few relationships between the HLA and response to DMTs in the disability for some types of HLA class I and II alleles in a specific subset of MS patients.

Cross-talks between the kidneys and the central nervous system in multiple sclerosis

Multiple sclerosis (MS) is an inflammatory demyelinating disease, which is considered as a common autoimmune disorder in young adults. A growing number of evidences indicated that the impairment in non-neural tissues plays a significant role in pathology of MS disease. There are bidirectional relationship, metabolic activities and functional similarity between central nervous system (CNS) and kidneys which suggest that kidney tissue may exert remarkable effects on some aspects of MS disorder and CNS impairment in these patients compels the kidney to respond to central inflammation. Recently, it has been well documented that hormonal secretion possesses the important role on CNS abnormalities. In this regard, due to the functional similarity and significant hormonal and non-hormonal relationship between CNS and kidneys, we hypothesized that kidneys exert significant effect on initiation, progression or amelioration of MS disease which might be regarded as potential therapeutic approach in the treatment of MS patients in the future.

Lower 25-Hydroxyvitamin D Is Associated with Higher Relapse Risk in Patients with Relapsing-Remitting Multiple Sclerosis

OBJECTIVES

To investigate the association between serum circulating 25-hydroxyvitamin D [25(OH) D] concentrations and exacerbation risk in Chinese patients with relapsing-remitting multiple sclerosis (RR-MS).

METHODS

From January 2014 to December 2014, consecutive RR-MS patients admitted to the Department of Neurology of our hospital were identified. Blood samples for 25(OH) D measurements were taken at admission. All included patients visited the outpatient clinic of our hospital 1 year after admission. The influence of serum 25[OH] D levels on exacerbation was performed by binary logistic regression analysis.

RESULTS

In this study, 109 patients finished the follow-up. Median follow-up time was 1 year (range 1.0-1.1). Twenty-one out of the 109 was at risk period for infection. A total of 32 patients experienced a total of 76 exacerbations during the study. In the follow-up, a total of 32 patients experienced exacerbations. Thus, the exacerbation rate was 29.4% (95%CI: 20.8%-37.9%). Exacerbation rates were found to decrease with increasing levels of serum 25-OH-D concentrations. For the quartiles category, the risk of an exacerbation was significantly increased in the group with first quartile compared to the group with fourth. Rate ratios for the first, second and third group were 4.2, 3.3 and 2.0, respectively (p for trend =0.011) when compared with the fourth group. Simultaneous evaluation of quartile categories of levels of serum 25(OH) D and infections showed that both factors were related to the exacerbation rate.

CONCLUSION

The data demonstrates that lower vitamin D status is a sign of more active disease in patients with RR-MS and suggests a beneficial effect of vitamin D on disease course in MS.

Vitamin D and Multiple Sclerosis: A Comprehensive Review

Numerous observational studies have suggested that there is a correlation between the level of serum vitamin D and MS risk and disease activity. To explore this hypothesis, a literature search of large, prospective, observation studies, epidemiological studies, and studies using new approaches such as Mendelian randomization was conducted. Available data and ongoing research included in this review suggest that the level of serum vitamin D affects the risk of developing MS and also modifies disease activity in MS patients. Newer Mendelian randomization analyses suggest there is a causal relationship between low vitamin D level and the risk of MS. Post-hoc evaluations from two phase 3 studies, BENEFIT and BEYOND, support the findings of observational trials. Study limitations identified in this review recognize the need for larger controlled clinical trials to establish vitamin D supplementation as the standard of care for MS patients. Though there is increasing evidence indicating that lower vitamin D levels are associated with increased risk of MS and with greater clinical and brain MRI activity in established MS, the impact of vitamin D supplementation on MS activity remains inadequately investigated.

Vitamin D and Neurological Diseases: An Endocrine View

Vitamin D system comprises hormone precursors, active metabolites, carriers, enzymes, and receptors involved in genomic and non-genomic effects. In addition to classical bone-related effects, this system has also been shown to activate multiple molecular mediators and elicit many physiological functions. In vitro and in vivo studies have, in fact, increasingly focused on the "non-calcemic" actions of vitamin D, which are associated with the maintenance of glucose homeostasis, cardiovascular morbidity, autoimmunity, inflammation, and cancer. In parallel, growing evidence has recognized that a multimodal association links vitamin D system to brain development, functions and diseases. With vitamin D deficiency reaching epidemic proportions worldwide, there is now concern that optimal levels of vitamin D in the bloodstream are also necessary to preserve the neurological development and protect the adult brain. The aim of this review is to highlight the relationship between vitamin D and neurological diseases.

The genetics of multiple sclerosis in Latin America

Background

In today’s globalised world, the heterogeneity of diseases such as multiple sclerosis has been studied since it has been suggested that ethnic differences, in conjunction with geographical and environmental factors, influence its incidence and prevalence.

Aim

Based on this, an attempt has been made to identify the genetic factors that may confer risk or protection, not only for developing multiple sclerosis but also for determining the course of its evolution.

Results

In Latin America we have some data about this, which have been replicated in different populations in the entire region, with very different results compared with other regions, which could explain not only the different frequencies in some populations, such as Caucasians, but also the course of the disease and the response to actual treatments. However, in addition to these findings, other associated epigenetic mechanisms have also been found in our populations, such as levels of vitamin D, parasitic diseases, and indigenous populations. Therefore, the study of epigenetics plays a crucial role in understanding the physiopathology of multiple sclerosis. It must be studied in each population, especially in Latin America, due to its broad heterogeneity.

Conclusion

It is very important to understand not only the genetic and external factors with these very specific effects in multiple sclerosis patients, but also the way they interact and are able to explain the frequency and some specific phenotypes of the disease in our populations besides the posibility to be a very specific treatment target.

Immunoregulatory effect of mast cells influenced by microbes in neurodegenerative diseases

When related to central nervous system (CNS) health and disease, brain mast cells (MCs) can be a source of either beneficial or deleterious signals acting on neural cells. We review the current state of knowledge about molecular interactions between MCs and glia in neurodegenerative diseases such as Multiple Sclerosis, Alzheimer's disease, Amyotrophic Lateral Sclerosis, Parkinson's disease, Epilepsy. We also discuss the influence on MC actions evoked by the host microbiota, which has a profound effect on the host immune system, inducing important consequences in neurodegenerative disorders. Gut dysbiosis, reduced intestinal motility and increased intestinal permeability, that allow bacterial products to circulate and pass through the blood-brain barrier, are associated with neurodegenerative disease. There are differences between the microbiota of neurologic patients and healthy controls. Distinguishing between cause and effect is a challenging task, and the molecular mechanisms whereby remote gut microbiota can alter the brain have not been fully elucidated. Nevertheless, modulation of the microbiota and MC activation have been shown to promote neuroprotection. We review this new information contributing to a greater understanding of MC-microbiota-neural cells interactions modulating the brain, behavior and neurodegenerative processes.

VDR and CYP24A1 Expression Analysis in Iranian Relapsing-Remitting Multiple Sclerosis Patients

OBJECTIVES

Multiple sclerosis (MS) is a common disease of the central nervous system.This disease may be initiated by either vitamin deficiency or triggered by abnormality in CYP24A1 and vitamin D receptor.

MATERIALS AND METHODS

In this case-control study, the expression of genes encoding vitamin D receptor (VDR) and CYP24A1 in relapsing-remitting MS (RR-MS) patients was compared with normal individuals in the Iranian population. RNA from whole blood of 50 RR-MS patients (HLA-DRB1*15-negative and responders to interferonbeta with a normal vitamin D level) and 50 normal controls was extracted. The levels of CYP24A1 and VDR expression were measured using real-time quantitative polymerase chain reaction.

RESULTS

The RR-MS group had a significantly more than 2 times higher expression level of VDR than the normal group (P=0.04). On the other hand, there was a 0.89 times decrease in the expression level of CYP24A1 in RR-MS patients which was not statistically significant. There was no linear correlation between the risk of expanded disability status scale of Kurtzke (EDSS) and the expression level of either CYP24A1 or VDR. In addition, the expression level of CYP24A1 or VDR was not correlated with the duration of the disease.

CONCLUSIONS

Up-regulation of VDR is likely to happen in RR-MS patients in the Iranian population. We did not observe a gene expression-phenotype correlation for CYP24A1 which may be due to limited statistical power as a result of the small sample size. Although the individuals taking part in this study had normal levels of vitamin D, the increase in VDR expression levels may perhaps be a response to a defect in vitamin D processing. Another possibility is that despite an increase in VDR expression level, factors such as micro-RNAs may result in their deactivation while an increase in VDR expression level can be seen as a compensatory response. Of course, further studies are required to identify the mechanism of action of vitamin D by analyzing genes involved in its signaling pathway, particularly VDR and CYP24A1.

Vitamin D and multiple sclerosis: An update

The most recent findings linking exposure to sun and vitamin D insufficiency to multiple sclerosis (MS) are reviewed. Due to insufficient sunshine and changing lifestyles, hypovitaminosis D is widespread in temperate countries. Numerous epidemiological studies have strongly suggested that sunshine and vitamin D insufficiency contributes to MS risk in these countries. Moreover, several large genetic studies in MS patients have recently stated unequivocally that diverse abnormalities involving vitamin D metabolism are related to the risk of the disease. The important implications of such results are discussed here. Then, the interactions of hypovitaminosis D with the other genetic and environmental protective and risk factors, such as the allele HLA DRB1*1501, Epstein-Barr virus infection, obesity, smoking and sexual hormones, are summarized. Vitamin D insufficiency and sufficiency could be a risk and a protective factor, respectively, among many other factors possibly continuously modulating the global MS risk from the mother's pregnancy to the triggering of MS in adulthood. However, many interactions between these different factors occur more particularly between conception and the end of adolescence, which corresponds to the period of maturation of the immune system and thymus and may be related to the dysimmune nature of the disease. The main mechanisms of action of vitamin D in MS appear to be immunomodulatory, involving the various categories of T and B lymphocytes in the general immune system, but neuroprotector and neurotrophic mechanisms could also be exerted at the central nervous system level. Furthermore, several controlled immunological studies performed in MS patients have recently confirmed that vitamin D supplementation has multiple beneficial immunomodulatory effects. However, there is still an enduring absence of major conclusive randomized clinical trials testing vitamin D supplementation in MS patients because of the quasi-insurmountable practical difficulties that exist nowadays in conducting and completing over several years such studies involving the use of a vitamin. Nevertheless, it should be noted that similar robust statistical models used in five different association studies have already predicted a favorable vitamin D effect reducing relapses by 50-70%. If there is now little doubt that vitamin D exerts a beneficial action on the inflammatory component of MS, the results are as yet much less clear for the progressive degenerative component. Lastly, until more information becomes available, vitamin D supplementation of MS patients, using a moderate physiological dose essentially correcting their vitamin insufficiency, is recommended.

miR-145 and miR20a-5p Potentially Mediate Pleiotropic Effects of Interferon-Beta Through Mitogen-Activated Protein Kinase Signaling Pathway in Multiple Sclerosis Patients

MicroRNAs (miRNAs) are crucial to the immunopathogenesis of multiple sclerosis (MS). The mechanism of action of interferon beta (IFN-β) in relapsing-remitting (RR) MS patients is largely unknown. miR-145 and miR-20a-5p previously reported as diagnosis biomarker in treatment naïve RRMS patients and their expression after IFN-β therapy might be indicative of molecular mechanism of IFN-β. Cross-talking between JAK/STAT pathway and complementary pathways like MAPK is important in IFN-β signaling. Here, in order to clarify the ambiguous molecular mechanism of IFN-β and evaluate the potential use of them as a biomarker for monitoring of therapy, we investigated the expression of miR-145 and miR-20a-5p in blood sample of 15 treatment naïve RRMS patients, 15 IFN-β-treated RRMS patients, and 15 healthy volunteers (HVs). In silico molecular signaling pathway enrichment analysis was fulfilled on validated and predicted targets of miR-145 and miR-20a-5p to probe the plausible role of them on molecular effects of IFN-β. We identified miR-145 and miR-20a-5p level was normalized in IFN-β-treated patients, and MAPK pathway was one of the most relevant pathways that recognized by molecular signaling pathway enrichment analysis. Moreover, ROC curve analysis of miR-145 indicated that this miRNA could be used for monitoring of response to IFN-β therapy. Restoration of miR-145 and miR-20a expression in IFN-β-treated patients suggests that pleiotropic effects of IFN-β might be through miRNAs. Enrichment of MAPK pathway underscores the importance of non-canonical pathways in IFN-β signaling.

Relation of Age, Sex and Bone Mineral Density to Serum 25-Hydroxyvitamin D Levels in Chinese Women and Men

OBJECTIVE

To investigate the relation of circulating 25-hydroxyvitamin D (25[OH]D) levels to age, sex, and bone mineral density (BMD) in adults living in Guangzhou Province.

METHODS

This cross-sectional study comprised 188 women and 122 men aged 17-88 years who were randomly sampled among community-dwelling Guangzhou residents. BMD at the lumbar spine and femoral neck was measured by dual energy X-ray absorptiometry, and serum concentrations of 25(OH)D, parathyroid hormone (PTH), procollagen I N-terminal peptide, and beta C-telopeptide of collagen were assayed by electrochemiluminescence immunoassay. Serum 25(OH)D concentrations were divided into four subgroups: severe deficiency (<10 ng/mL), deficiency (10-20 ng/mL), insufficiency (20-30 ng/mL), and sufficiency (≥30 ng/mL).

RESULTS

The mean age of participants was 47.39 ± 19.32 years. Serum 25(OH)D levels were significantly lower in women than men (25.35 ± 6.59 ng/mL vs 27.25 ± 7.94 ng/mL, P < 0.05). The prevalence of 25(OH)D severe deficiency (<10 ng/mL) was 1.6% in men, zero in women; 25(OH)D deficiency (10-20 ng/mL) was 22.9% in women and 20.5% in men; and 25(OH)D insufficiency (20-30 ng/mL) was 73.4% in women and 65.6% in men. An inverse relationship between serum 25(OH)D levels and age (r = -0.249, P < 0.01) was observed in men, but no correlation was found in women (r = 0.130, P > 0.05). Serum 25(OH)D levels were positively associated with lumbar spine and femoral neck BMD (r = 0.382, P < 0.01; r = 0.384, P < 0.01, respectively) in elderly women and (r = 0.332, P < 0.05; r = 0.260, P < 0.05, respectively) and in young men. When adjustments were made for age, correlations between serum 25(OH)D levels and lumbar spine and femoral neck BMD persisted (r = 0.325, P < 0.05; r = 0.323, P < 0.05, respectively) in elderly women. However, age-adjusted serum 25(OH)D levels were positively correlated with BMD at lumbar spine (r = 0.278, P < 0.05) but not at femoral neck (r = 0.165, P > 0.05) in young men. No association between unadjusted or age-adjusted serum 25(OH)D levels and lumbar spine and femoral neck BMD was found in young and middle-aged women and in middle-aged and elderly men. Neither serum PTH levels nor bone turnover markers were related to unadjusted and age-adjusted serum 25(OH)D levels in our participants.

CONCLUSION

More than two-third of participants residing in Guangzhou had vitamin D insufficiency. Serum 25(OH)D level is an important biomarker for BMD in elderly women and young men.

The immunogenetics of multiple sclerosis. The frequency of HLA-alleles class 1 and 2 is lower in Southern Brazil than in the European population

ABSTRACT Objective To study the HLA of class 1and 2 in a multiple sclerosis (MS) population to verify the susceptibility for the disease in the Southern Brazil. Methods We analyzed patients with MS and controls, by direct sequencing of the genes related to HLA DRB1, DQB1, DPB1, A, B and C alleles with high resolution techniques. Results We found a lower frequency of all HLA alleles class 1 and 2 in MS and controls comparing to the European population. Several alleles had statistical correlation, but after Bonferroni correction, the only allele with significance was the HLA-DQB1*02:03, which has a positive association with MS. Conclusions Our data have different frequency of HLA-alleles than the previous published papers in the Southeast Brazil and European population, possible due to several ethnic backgrounds.

Vitamin D and remyelination in multiple sclerosis

INTRODUCTION

Several studies have found an association between multiple sclerosis and vitamin D (VD) deficiency, which suggests that VD may play a role in the immune response. However, few studies have addressed its role in remyelination.

DEVELOPMENT

The VD receptor and the enzymes transforming VD into metabolites which activate the VD receptor are expressed in central nervous system (CNS) cells, which suggests a potential effect of VD on the CNS. Both in vitro and animal model studies have shown that VD may play a role in myelination by acting on factors that influence the microenvironment which promotes both proliferation and differentiation of neural stem cells into oligodendrocyte progenitor cells and oligodendrocytes. It remains unknown whether the mechanisms of internalisation of VD in the CNS are synergistic with or antagonistic to the mechanisms that facilitate the entry of VD metabolites into immune cells.

CONCLUSIONS

VD seems to play a role in the CNS and our hypothesis is that VD is involved in remyelination. Understanding the basic mechanisms of VD in myelination is necessary to manage multiple sclerosis patients with VD deficiency.

Vitamin D level status in Thai neuromyelitis optica patients

Vitamin D status of Thai clinically isolated syndrome (CIS), multiple sclerosis (MS) and NMO/neuromyelitis optica spectrum disorders (NMOSD) patients were prospectively collected (N=130). Its associations with disability score, and disease activity were sought. Mean vitamin D levels were not significantly different (CIS, 22.18±8.2; MS, 23.41±11.9; NMO/NMOSD, 23.54±9.3ng/mL; p=0.857). Prevalence of vitamin D insufficiency and deficiency (≤30ng/mL) was 73-80%. Neither disability score nor disease activity was associated with vitamin D level. Vitamin D insufficiency was common in Thai CIS, MS, and NMO/NMOSD patients without association with disability or disease activity.

Factors associated with onset, relapses or progression in multiple sclerosis: A systematic review

Multiple sclerosis (MS) is a chronic disease of the central nervous system with an unidentified etiology. We systematically reviewed the literature on the possible risk factors associated with MS disease onset, relapses and progression from 1960 to 2012 by accessing six databases and including relevant systematic reviews, meta-analyses, case-control or cohort studies. The focus was on identifying modifiable risk factors. Fifteen systematic reviews and 169 original articles were quality assessed and integrated into a descriptive review. Best evidence, which included one or more prospective studies, suggested that lower exposure to sunlight and/or lower serum vitamin D levels were associated with an increased risk of developing MS onset and subsequent relapses, but a similar quality of evidence was lacking for disease progression. Prospective studies indicated that cigarette smoking may increase the risk of MS as well as accelerate disease progression, but whether smoking altered the risk of a relapse was largely unknown. Infections were implicated in both risk of developing MS and relapses, but data for progression were lacking. Specifically, exposure to the Epstein-Barr virus, particularly if this manifested as infectious mononucleosis during adolescence, was associated with increased MS risk. Upper respiratory tract infections were most commonly associated with an increase in relapses. Relapse rates typically dropped during pregnancy, but there was no strong evidence to suggest that pregnancy itself altered the risk of MS or affected long-term progression. Emerging research with the greatest potential to impact public health was the suggestion that obesity during adolescence may increase the risk of MS; if confirmed, this would be of major significance.

Advances in the immunopathogenesis of multiple sclerosis

PURPOSE OF REVIEW

Recent studies indicate a role for immune dysregulation in the pathogenesis of multiple sclerosis, an inflammatory demyelinating and degenerative disease of the central nervous system. This review addresses the current mechanisms of immune dysregulation in the development of multiple sclerosis, including the impact of environmental risk factors on immunity in both multiple sclerosis and its animal models.

RECENT FINDINGS

CD4 T-helper (Th) cells have long been implicated as the main drivers of pathogenesis of multiple sclerosis. However, current studies indicate that multiple sclerosis is largely a heterogeneous disease process, which involves both innate and adaptive immune-mediated inflammatory mechanisms that ultimately contribute to demyelination and neurodegeneration. Therefore, B cells, CD8 T cells, and microglia/macrophages can also play an important role in the immunopathogenesis of multiple sclerosis apart from proinflammatory CD4 Th1/Th17 cell subsets. Furthermore, increasing evidence indicates that environmental risk factors, such as Vitamin D deficiency, Epstein-Barr virus, smoking, Western diet, and the commensal microbiota, influence the development of multiple sclerosis through interactions with genetic variants of multiple sclerosis, thus leading to the dysregulation of immune responses.

SUMMARY

A better understanding of immune-mediated mechanisms in the pathogenesis of multiple sclerosis and the contribution of environmental risk factors toward the development of multiple sclerosis will help further improve therapeutic approaches to prevent disease progression.

Latitude, sun exposure and vitamin D supplementation: associations with quality of life and disease outcomes in a large international cohort of people with multiple sclerosis

BACKGROUND

A growing evidence base implicates vitamin D, sun exposure and latitude in the aetiology of multiple sclerosis (MS), however there are less data on the associations of these variables with disease outcomes.

METHODS

We undertook a cross-sectional survey of over 2000 people with MS recruited through internet platforms, seeking self-reported data on geographical location, intentional sun exposure for health, and supplementation with vitamin D, among other lifestyle variables. We also requested data on health-related quality of life (MSQOL-54), self-reported doctor-diagnosed relapse rate, and disability (Patient Determined Disease Steps). Bivariate and multivariate analyses were used for comparisons, including multiple linear regression modeling.

RESULTS

Of 2301 participants, 82.3 % were female, median age was 45 years (IQR 38-53 years), with a median time since diagnosis of 6 years (IQR 3-12 years), the majority (61.6 %) having relapsing-remitting MS. Nearly two-thirds (64.6 %) lived in the Northern hemisphere, mostly in developed countries. Most (66.8 %) reported deliberate sun exposure to raise their vitamin D level, and the vast majority (81.8 %) took vitamin D supplements, mostly 2000-5000 IU a day on average. Unadjusted regression modeling incorporating deliberate sun exposure, latitude and vitamin D supplementation showed strong associations of sun exposure with HRQOL which disappeared when controlling for gender, age, disability, physical activity, and fish consumption. In contrast, associations between vitamin D supplementation and HRQOL were maintained adjusting for these variables, with a dose-response effect. Only latitude had significant adjusted associations with disability, with an increase of latitude by one degree (further from the equator) predicting increased odds of moderate disability (OR 1.02 (95 % CI 1.01-1.04)) or high disability (OR 1.03 (95 % CI 1.01-1.05)) compared to no/mild disability. Similarly, latitude was related to relapse rate, with increase in latitude of 1 degree associated with increased odds of having more relapses over the previous year (1.01 (1.00-1.02)).

CONCLUSIONS

We detected significant associations between latitude, deliberate sun exposure and vitamin D supplementation and health outcomes of this large group of people with MS. Vitamin D is likely to have a key role in these associations and its role in the health outcomes of people with MS urgently requires further study.

Association between vitamin D receptor polymorphisms and multiple sclerosis: systematic review and meta-analysis of case-control studies

Vitamin D receptor (VDR) polymorphisms have been studied as potential contributors to multiple sclerosis (MS). However, published studies differ with respect to study design and the significance of the effects detected. The aim of this study was to quantify the magnitude of the risk associated with the TaqI, BsmI, ApaI and FokI VDR polymorphisms in MS using a meta-analysis approach. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, we conducted a systematic search and meta-analysis of the literature. Subgroup analyses were performed to detect potential sources of heterogeneity from the selected study characteristics. The stability of the summary risk was evaluated using sensitivity analyses. The meta-analysis included a total of 3300 cases and 3194 controls from 13 case-control studies. There were no significant associations found between TaqI and BsmI polymorphisms and MS risk. The association between the ApaI polymorphism and MS risk was significant in the homozygous and codominant models (P=0.013 and P=0.031, respectively), suggesting that the AA ApaI genotype might be a significant MS risk factor. Publication year and age significantly affected the association between TaqI polymorphisms and MS (P=0.014 and P=0.010, respectively), which indicates a protective effect of the major T allele. The AA ApaI and FF FokI genotypes are significant risk factors for MS. The association between the TaqI polymorphism and MS risk is significantly affected by study characteristics.

Controlled trials of vitamin D, causality and type 2 statistical error

Two recent studies published in The Lancet (Autier et al. (2013) Lancet Diabetes Endocrinol 2, 76-89 and Bolland et al. (2014) Lancet Diabetes Endocrinol 2, 307-320) have concluded that low levels of vitamin D are not a cause but a consequence of ill health brought about by reduced exposure to the sun, an association known as 'reverse causality'. The scientific evidence and reasoning for these conclusions are examined here and found to be faulty. A null result in a clinical trial of vitamin D in adults need not lead to a conclusion of reverse causation when low vitamin D is found in observational studies of the same disease earlier in life. To assume an explanation of reverse causality has close similarities with type 2 statistical error. For example, a null result in providing vitamin D for treatment of adult bones that are deformed in the pattern of the rachitic rosary would not alter the observation that lack of vitamin D can cause rickets in childhood and may have lasting consequences if not cured with vitamin D. Other examples of diseases considered on a lifetime basis from conception to adulthood are used to further illustrate the issue, which is evidently not obvious and is far from trivial. It is concluded that deficiency of vitamin D in cohort studies, especially at critical times such as pregnancy and early life, can be the cause of a number of important diseases. Denial of the possible benefits of vitamin D, as suggested by insistent interpretation of studies with reverse causation, may lead to serious harms, some of which are listed.

Vitamin D-binding protein controls T cell responses to vitamin D

Background

In vitro studies have shown that the active form of vitamin D₃, 1α,25-dihydroxyvitamin D3 (1,25(OH)₂D₃), can regulate differentiation of CD4⁺ T cells by inhibiting Th1 and Th17 cell differentiation and promoting Th2 and Treg cell differentiation. However, the serum concentration of 1,25(OH)₂D₃ is far below the effective concentration of 1,25(OH)₂D₃ found in in vitro studies, and it has been suggested that 1,25(OH)₂D₃ must be produced locally from the inactive precursor 25-hydroxyvitamin D3 (25(OH)D₃) to affect ongoing immune responses in vivo. Although it has been reported that activated T cells express the 25(OH)D-1α-hydroxylase CYP27B1 that converts 25(OH)D₃ to 1,25(OH)₂D₃, it is still controversial whether activated T cells have the capacity to produce sufficient amounts of 1,25(OH)₂D₃ to affect vitamin D-responsive genes. Furthermore, it is not known how the vitamin D-binding protein (DBP) found in high concentrations in serum affects T cell responses to 25(OH)D₃.

Results

We found that activated T cells express CYP27B1 and have the capacity to produce sufficient 1,25(OH)₂D₃ to affect vitamin D-responsive genes when cultured with physiological concentrations of 25(OH)D₃ in serum-free medium. However, if the medium was supplemented with serum or purified DBP, DBP strictly inhibited the production of 1,25(OH)₂D₃ and 25(OH)D₃-induced T cell responses. In contrast, DBP did not inhibit the effect of exogenous 1,25(OH)₂D₃. Actin, arachidonic acid and albumin did not affect the sequestration of 25(OH)D₃ by DBP, whereas carbonylation of DBP did.

Conclusions

Activated T cells express CYP27B1 and can convert 25(OH)D₃ to 1,25(OH)₂D₃ in sufficiently high concentrations to affect vitamin D-responsive genes when cultured in serum-free medium. However, DBP sequesters 25(OH)D₃ and inhibits the production of 1,25(OH)₂D₃ in T cells. To fully exploit the immune-regulatory potential of vitamin D, future studies of the mechanisms that enable the immune system to exploit 25(OH)D₃ and convert it to 1,25(OH)₂D₃in vivo are required.

Electronic supplementary material

The online version of this article (doi:10.1186/s12865-014-0035-2) contains supplementary material, which is available to authorized users.

Specific aspects of modern life for people with multiple sclerosis: considerations for the practitioner

Multiple sclerosis (MS) is a chronic, debilitating, neurodegenerative disease that has a high impact on patients' quality of life. Individuals are often diagnosed in early adulthood and are faced with the difficulty of managing their lifestyle within the context of this chronic illness. Here we review factors that influence the disease course and the challenges that might be encountered when managing patients with MS. The majority of diagnosed patients are women of childbearing age, making pregnancy-related issues a key concern. MS typically stabilizes during pregnancy and evidence suggests that the disease has no impact on the risk of complications or outcomes. However, the effect of disease-modifying therapies on outcomes is less clear, and discontinuation of treatment prior to pregnancy or when breastfeeding is recommended. Awareness of genetic risk factors is important for patients planning a family, as several genes increase the risk of MS. Further aspects that require consideration include infections, vaccinations, environmental factors, surgery and the emergence of osteoporosis. Vaccinations are generally not a risk factor for MS and may be beneficial in terms of protection against infection and reducing the number of relapses. Environmental factors such as vitamin D deficiency, low exposure to sunlight, smoking and Epstein-Barr virus infection can all negatively influence the disease course. Furthermore, osteoporosis is generally higher in patients with MS than the general population, and the risk is increased by the environmental and genetic factors associated with the disease; bone mineral density should be assessed and smoking cessation and correction of serum vitamin D levels are recommended. Finally, as patients with MS are typically young, they are at low risk of surgery-related complications, although they should be carefully monitored postoperatively. Awareness of, and planning around, these factors may minimize the impact of the disease on patients' lifestyle.