Vitamin D and Demyelinating Diseases: Neuromyelitis Optica (NMO) and Multiple Sclerosis (MS)

Tremendous Fidelity of Vitamin D3 in Age-related Neurological Disorders

Vitamin D3 (VD) is a secosteroid hormone and shows a pleiotropic effect in brain-related disorders where it regulates redox imbalance, inflammation, apoptosis, energy production, and growth factor synthesis. Vitamin D3's active metabolic form, 1,25-dihydroxy Vitamin D3 (1,25(OH)2D3 or calcitriol), is a known regulator of several genes involved in neuroplasticity, neuroprotection, neurotropism, and neuroinflammation. Multiple studies suggest that VD deficiency can be proposed as a risk factor for the development of several age-related neurological disorders. The evidence for low serum levels of 25-hydroxy Vitamin D3 (25(OH)D3 or calcidiol), the major circulating form of VD, is associated with an increased risk of Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), dementia, and cognitive impairment. Despite decades of evidence on low VD association with neurological disorders, the precise molecular mechanism behind its beneficial effect remains controversial. Here, we will be delving into the neurobiological importance of VD and discuss its benefits in different neuropsychiatric disorders. The focus will be on AD, PD, and HD as they share some common clinical, pathological, and epidemiological features. The central focus will be on the different attributes of VD in the aspect of its anti-oxidative, anti-inflammatory, anti-apoptotic, anti-cholinesterase activity, and psychotropic effect in different neurodegenerative diseases.

Neuromyelitis optica spectrum disorders relapses and seasonal influence in an equatorial country cohort

INTRODUCTION

Information about seasonal distribution of Neuromyelitis optica spectrum disorders (NMOSD) attacks, particularly in tropical countries, has rarely been described and the reported data are diverse.

OBJECTIVE

To evaluate influence of seasonal variation in NMOSD relapses in an equatorial country.

PATIENTS AND METHODS

Exploratory observational, retrospective ecological study in a cohort of patients with NMOSD followed from January 2008 to December 2019. Data of demographic, clinical information, characteristics of relapses and seasonal temporal variation were recorded. Also, the annual, monthly and intra-annual seasonal variation of relapses was quantified. A negative binomial regression was used to estimate the associations between the number of relapses and climatic and temporal variables.

RESULTS

One hundred thirteen patients were included, most of them were female (89.38%), with a mean age at NMOSD diagnosis was 44.97 (±13.98) and the median of relapses per patient were 2 relapses (IQR 1-3). The patients presented 237 relapses, most of these in AQP4 seropositive patients (87.76%) and longitudinal extensive myelitis was the most frequent type of relapse (53.59%). According to the temporal variation, relapses were more common in the second rainy season (28.69%) during November and December. However, there weren't significant differences in the number of relapses between seasons and climatic variables in the multivariable model.

CONCLUSION

The number of NMOSD relapses in this equatorial country cohort did not exhibit any significant associations with climatic variations, including changes in rainy or dry seasons.

Role of Neural Stem Cells and Vitamin D Receptor (VDR)-Mediated Cellular Signaling in the Mitigation of Neurological Diseases

Specific stem cell-based therapies for treating Alzheimer's disease, Parkinson's disease, and schizophrenia are gaining importance in recent years. Accumulating data is providing further support by demonstrating the efficacy of neural stem cells in enhancing the neurogenesis in the aging brain. In addition to stem cells, recent studies have shown the efficacy of supplementing vitamin D in promoting neurogenesis and neuronal survival. Studies have also demonstrated the presence of mutational variants and single-nucleotide polymorphisms of the vitamin D receptor (VDR) in neurological disorders; however, implications of these mutations in the pathophysiology and response to drug treatment are yet to be explored. Hence, in this article, we have reviewed recent reports pertaining to the role of neural stem cells and VDR-mediated cellular signaling cascades that are involved in enhancing the neurogenesis through Wnt/β-catenin and Sonic Hedgehog pathways. This review benefits neurobiologists and pharmaceutical industry experts to develop stem cell-based and vitamin D-based therapies to better treat the patients suffering from neurological diseases.

Incidence of neuromyelitis optica spectrum disorders in China: a large cohort study using claim data

OBJECTIVES

Population-based studies estimating the incidence of neuromyelitis optica spectrum disorders (NMOSDs) in Asia are limited, and the relationship between latitude and incidence has been scarcely investigated. We aimed to estimate the incidence of NMOSDs in Chinese adults and explore their relationship to latitude.

DESIGN

Cohort study based on data from the Urban Employee Basic Medical Insurance in China.

PARTICIPANTS

177 million people were followed from 2016 to 2017 in 20 provinces.

PRIMARY OUTCOME MEASURES

The incidence rate was estimated by Poisson distribution and reported as age-adjusted and sex-adjusted rates using the standard population.

RESULTS

There were 1313 incident NMOSD cases, with an overall incidence of 0.41 (95% CIs: 0.39 to 0.43) per 100 000 person-years. The incidence in females was higher, with a female-to-male IRR of 4.52. The incidence increased with age, peaking at 55-64 years in females and 65-74 years in males and then decreasing thereafter. The female-to-male IRRs were higher in those <55 years. The association between latitude and incidence was not statistically significant.

CONCLUSIONS

The incidence of NMOSD in Chinese adults was 0.41 per 100 000 person-years. There is no latitude gradient observed. Sex and age influence the risk of NMOSD, suggesting the role of genetic, hormonal and other related factors in the pathophysiology.

VITAMIN D AND OPHTHALMOPATHIAS. A REVIEW

The importance of vitamin D3 (hydroxycholecalciferol) as one of the liposoluble vitamins is known in the prevention and treatment of metabolic bone diseases (rickets, osteomalacia, osteoporosis). In recent years, however, information has increased on the importance of vitamin D3 in numerous organ systems and in the pathogenesis of various diseases, e. g. ophthalmopathies. The immunological functions of vitamin D3 are the subject of studies dealing with autoimmune optic nerve disorders and their results appear to have a positive effect on demyelinating diseases. It also plays an important role in maintaining the thickness of the retinal nerve fiber layer, but its additional administration has not been successful. Optical neuritis may be the first sign of multiple sclerosis. It appears that sufficient serum vitamin D3 levels may protect patients from deterioration in the form of a further attack of demyelination. The course of diabetic retinopathy is probably also influenced by vitamin D3, inter alia, by correlating the fact that its receptor and the enzymes of its metabolism are expressed on the retina. Low serum levels of vitamin D3 may even trigger age-related macular degeneration. Conversely, higher dietary intake of vitamin D3 may positively affect neovascularization. The optimal level of hydroxycholecalciferol is between 60 and 200 nmol /l, the severe deficit represents a decrease below 25 nmol/l. The body can normally produce up to 10,000 IU of this vitamin after exposure to sunlight. However, the demonstration of its protective character in connection with the mentioned diseases of the retina and optic nerve will require a sufficient number of studies to confirm the facts found so far about this rediscovered vitamin.

Effects of Vitamin D and Dexamethasone on Lymphocyte Proportions and Their Associations With Serum Concentrations of 25-Hydroxyvitamin D3 In Vitro in Patients With Multiple Sclerosis or Neuromyelitis Optica Spectrum Disorder

Background

Clear associations have been found between vitamin D deficiency and several autoimmune diseases including multiple sclerosis (MS). However, the benefits of vitamin D supplementation on disease management remain a matter of debate.

Objective and Methods

Patients with MS (N=12) and neuromyelitis optica spectrum disorder (NMOSD; N=12) were enrolled along with 15 healthy controls. Changes in lymphocyte subset proportions during stimulation of their peripheral blood mononuclear cells (PBMCs) with the active form of vitamin D, 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃), and correlations with serum concentrations of the vitamin D precursor 25-hydroxyvitamin D₃ (serum 25(OH)D₃) were explored. The impact of 1,25(OH)₂D₃ stimulation on the expression of vitamin-D-responsive genes in immune cells was also investigated.

Results

In both MS and NMOSD, stimulation of PBMCs with 1,25(OH)₂D₃ followed by steroid suppressed the proliferation of total lymphocytes and T cells. The ratio of CD19⁺CD27⁺ memory B cells (Bmem) to all B cells after stimulation with 1,25(OH)₂D₃ was negatively correlated with serum 25(OH)D₃ in MS (Spearman’s ρ=–0.594, p=0.042), but positively correlated in NMOSD (Pearson’s r = 0.739, p=0.006). However, there was no relationship between the ratio of Bmem to CD19⁺CD24⁺CD38⁺ regulatory B cells and serum 25(OH)D₃ in either MS or NMOSD. In addition, the level of 1,25(OH)₂D₃-induced CYP24A1 mRNA expression in PBMCs was significantly and negatively correlated with serum 25(OH)D₃ (for ΔC_T, r=0.744, p=0.014) in MS.

Conclusion

These findings suggest a beneficial impact of stimulation of PBMCs with vitamin D followed by steroid on the T-cell population. The association between patient serum 25(OH)D₃ and the proportion of Bmem under immune-cell stimulation differed between MS and NMOSD. Further investigations are warranted with larger patient populations.

Association of serum levels and receptor genes BsmI, TaqI and FokI polymorphisms of vitamin D with the severity of multiple sclerosis

PURPOSE

Multiple sclerosis (MS) is a chronic inflammatory and neurodegenerative disease. Vitamin D has a major role in preventing inflammatory disorders. Therefore, any alteration in vitamin D receptor (VDR) might be a genetic risk factor for MS development. This study aimed to evaluate the effect of serum levels and VDR FokI, BsmI, and TaqI gene polymorphisms on the severity of MS.

METHODS

This case-control study recruited 160 MS patients (71.9% females, mean age of 34.3 ± 8.3 years) and 162 (66.7% females, mean age 35.4 ± 7.9 year) age, sex, and ethnicity matched healthy controls. FokI (rs2228570), BsmI (rs1544410), and TaqI (rs731236) polymorphisms were carried out using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Demographic, clinical parameters, and the levels of vitamin D were compared between groups.

RESULTS

We found that the frequency of FokI and TaqI polymorphisms significantly differed between the patients and the controls (p = 0.0127 and p = 0.0236, respectively). The MS patients had low levels of vitamin D compared to the controls (p = 0.011). In addition, TaqI T/C polymorphism significantly decreased the levels of vitamin D in the MS patients (p = 0.002). However, there was no significant association between FokI or BsmI SNPs and the levels of vitamin D in MS patients (p > 0.5).

CONCLUSION

Our results suggest that FokI and TaqI polymorphisms of VDR are associated with MS risk and TaqI polymorphism is associated with Vitamin D levels in MS patients. Meanwhile, no difference was observed between VDR gene polymorphisms and any types of MS.

Epstein-Barr Virus and Multiple Sclerosis

Multiple sclerosis (MS) is a neurologic disease affecting myelinated nerves in the central nervous system (CNS). The disease often debuts as a clinically isolated syndrome, e.g., optic neuritis (ON), which later develops into relapsing-remitting (RR) MS, with temporal attacks or primary progressive (PP) MS. Characteristic features of MS are inflammatory foci in the CNS and intrathecal synthesis of immunoglobulins (Igs), measured as an IgG index, oligoclonal bands (OCBs), or specific antibody indexes. Major predisposing factors for MS are certain tissue types (e.g., HLA DRB1*15:01), vitamin D deficiency, smoking, obesity, and infection with Epstein-Barr virus (EBV). Many of the clinical signs of MS described above can be explained by chronic/recurrent EBV infection and current models of EBV involvement suggest that RRMS may be caused by repeated entry of EBV-transformed B cells to the CNS in connection with attacks, while PPMS may be caused by more chronic activity of EBV-transformed B cells in the CNS. In line with the model of EBV's role in MS, new treatments based on monoclonal antibodies (MAbs) targeting B cells have shown good efficacy in clinical trials both for RRMS and PPMS, while MAbs inhibiting B cell mobilization and entry to the CNS have shown efficacy in RRMS. Thus, these agents, which are now first line therapy in many patients, may be hypothesized to function by counteracting a chronic EBV infection.

Teriflunomide preserves peripheral nerve mitochondria from oxidative stress-mediated alterations

Mitochondrial dysfunction is a common pathological hallmark in various inflammatory and degenerative diseases of the central nervous system, including multiple sclerosis (MS). We previously showed that oxidative stress alters axonal mitochondria, limiting their transport and inducing conformational changes that lead to axonal damage. Teriflunomide (TFN), an oral immunomodulatory drug approved for the treatment of relapsing forms of MS, reversibly inhibits dihydroorotate dehydrogenase (DHODH). DHODH is crucial for de novo pyrimidine biosynthesis and is the only mitochondrial enzyme in this pathway, thus conferring a link between inflammation, mitochondrial activity and axonal integrity. Here, we investigated how DHODH inhibition may affect mitochondrial behavior in the context of oxidative stress. We employed a model of transected murine spinal roots, previously developed in our laboratory. Using confocal live imaging of axonal mitochondria, we showed that in unmanipulated axons, TFN increased significantly the mitochondria length without altering their transport features. In mitochondria challenged with 50 µM hydrogen peroxide (H₂O₂) to induce oxidative stress, the presence of TFN at 1 µM concentration was able to restore mitochondrial shape, motility, as well as mitochondrial oxidation potential to control levels. No effects were observed at 5 µM TFN, while some shape and motility parameters were restored to control levels at 50 µM TFN. Thus, our data demonstrate an undescribed link between DHODH and mitochondrial dynamics and point to a potential neuroprotective effect of DHODH inhibition in the context of oxidative stress-induced damage of axonal mitochondria.