Metabolomics: A potential way to know the role of vitamin D on multiple sclerosis

Vitamin D3 levels in women and factors contributing to explain metabolic variations

The elucidated metabolism of vitamin D₃ in humans has been the support to explain the high involvement of this liposoluble vitamin in physiological functions. Clinical studies have associated levels of vitamin D₃ metabolites with several disorders. Despite this knowledge, there is a controversy regarding the estimation of deficiency and the physiological and supraphysiological levels of vitamin D₃ metabolites. The association between serum concentrations of vitamin D₃ metabolites and several potentially influential factors (namely, age and anthropometric, seasonal, spatial and metabolic factors) is analyzed in this study. For this purpose, 558 women were recruited and interviewed in several Spanish provinces before blood sampling. Serum vitamin D₃ and its metabolites were determined using an SPE-LC-MS/MS platform. The concentration range for vitamin D₃ was 1.7-21.1 nmol/L and was influenced by body mass index (BMI), waist-to-hip ratio (WHR) and seasonal period. 25-hydroxyvitamin D₃ levels were within 4.8-147.2 nmol/L and were related to WHR, season, latitude and calcium intake. The range of 24,25-dihydroxyvitamin D₃, 0.3-15.0 nmol/L, was associated to BMI, WHR, season, latitude and calcium intake. Finally, energy intake influenced the vitamin D 25-hydroxylase through the 25-hydroxyvitamin D₃/vitamin D₃ ratio, which regulates the synthesis of the circulating form. According to these results, it is worth emphasizing the relevance of all these factors to explain the variability in serum levels of vitamin D₃ and its metabolites. All these factors should be considered in future studies assessing the alteration of vitamin D₃ metabolism.

Evaluating the Effects of Dietary Interventions on Disease Progression and Symptoms of Adults with Multiple Sclerosis: An Umbrella Review

Multiple sclerosis (MS) is a chronic inflammatory autoimmune disease of the central nervous system. The role of diet in the progression of MS and severity of symptoms remains unclear. Various systematic literature reviews (SRs) have reported the effects of single nutrients on MS progression or the role of dietary factors on specific symptoms of MS. Narrative reviews have examined the effects of various dietary patterns in MS populations. An umbrella review was undertaken to collate the findings from review articles and evaluate the strength of the scientific evidence of dietary interventions for people living with MS. Scientific databases including MEDLINE, PubMed, CINAHL, and The Cochrane Library were systematically searched up to April 2019. Review articles and meta-analyses were included if they examined the effect of any dietary intervention in adult populations with MS. Outcomes included MS progression indicated by relapses, disability, MRI activity and disease classification, and MS symptoms. Characteristics and findings from both review articles and their included primary studies were extracted and summarized. A total of 19 SRs and 43 narrative reviews were included. Vitamin D and PUFAs were the most commonly studied interventions. Across SR studies, vitamin D supplementation had no significant effect on relapses, MRI, or disability progression; however, an inverse association was found between vitamin D status and disability scores through observational studies. Effects of PUFA supplementation on major outcomes of MS progression were inconsistent across review articles. Other interventions less commonly studied included vitamin, mineral, and herbal supplementation and varying dietary patterns. Strong consistent evidence is lacking for dietary interventions in persons with MS. The body of evidence is primarily focused around the isolation of individual nutrients, many of which demonstrate no effect on major outcomes of MS progression. Stronger food-focused studies are required to strengthen the evidence.

Metabolomic Profiling in Neuromyelitis Optica Spectrum Disorder Biomarker Discovery

There is no specific test for diagnosing neuromyelitis optica spectrum disorder (NMOSD), a disabling autoimmune disease of the central nervous system. Instead, diagnosis relies on ruling out other related disorders with overlapping clinical symptoms. An urgency for NMOSD biomarker discovery is underscored by adverse responses to treatment following misdiagnosis and poor prognosis following the delayed onset of treatment. Pathogenic autoantibiotics that target the water channel aquaporin-4 (AQP4) and myelin oligodendrocyte glycoprotein (MOG) contribute to NMOSD pathology. The importance of early diagnosis between AQP4-Ab⁺ NMOSD, MOG-Ab⁺ NMOSD, AQP4-Ab⁻ MOG-Ab⁻ NMOSD, and related disorders cannot be overemphasized. Here, we provide a comprehensive data collection and analysis of the currently known metabolomic perturbations and related proteomic outcomes of NMOSD. We highlight short chain fatty acids, lipoproteins, amino acids, and lactate as candidate diagnostic biomarkers. Although the application of metabolomic profiling to individual NMOSD patient care shows promise, more research is needed.

Urinary metabolic profiles after vitamin D2 versus vitamin D3 supplementation in prediabetes

Aim

To assess the potential biological differences between vitamin D₂ and D₃ using urinary metabolite profiles in response to vitamin D₃ or D₂ supplementation.

Method

Subjects consisted of 29 subjects with impaired fasting glucose and/or impaired glucose tolerance. Subjects were randomized into two groups, vitamin D₂ (20,000 IU weekly, n = 14) or vitamin D₃ (15,000 IU weekly, n = 15). Urine and serum samples were taken at two different time points for each subject (at baseline and at 12 weeks). Urinary metabolite profiling was performed by liquid chromatography electrospray ionization quadrupole time-of-flight mass spectrometry (LC-ESI-QTOF-MS). Serum calcium was analyzed on an automated biochemical analyzer and serum intact parathyroid hormone was determined by electrochemiluminescence immunoassay.

Results

At baseline, there was no statistically significant difference in clinical characteristics including age, gender, body mass index, waist circumference and 25-hydroxyvitamin D (25(OH)D) levels between the 2 groups. Weekly administration of 20,000 U D₂ for 12 weeks resulted in comparable 25(OH)D concentrations as compared to weekly 15,000 U D₃ supplementation (97.8 ± 305 vs. 96.8 ± 3.4 nmol/L, p = 0.84). No difference in serum calcium (2.3 ± 0.03 vs. 2.2 ± 0.03 nmol/L, p = 0.52) or intact parathyroid hormone (5.3 ± 0.3 vs. 4.9 ± 0.5 pmol/L, p = 0.54) at 12 weeks was found. Principle component analysis did not reveal apparent segregation of metabolites according to D₂ or D₃ supplementation. Moreover, using partial least square regression, no apparent separation between the D₂ and the D₃ group was found. No important metabolite influencing the separation of the D₂ from the D₃ group was found using variables importance on projection analysis.

Conclusions

At comparable circulating 25(OH)D concentrations, vitamin D₂ or D₃ supplementation does not appear to result in different urinary metabolite profiles. Our finding does not support a biological difference between vitamin D₂ and D₃.

Comparison of vitamin D metabolites in wild and captive baboons

Vitamin D adequacy is essential for multiple physiologic processes. With limited exposure to sunlight for vitamin D3 synthesis, captive primates are supplemented with vitamin D3 (cholecalciferol). Vitamin D metabolite data from wild primates living indigenously could suggest optimum levels. The purpose of this study was to: 1) to explore whether baboons, a speciose genus whose members have significant exposed skin, coat color variation and wide geographical distribution, mirrors the skin pigmentation-vitamin D relationship found in humans; 2) compare vitamin D metabolite levels in wild and captive members of the same or similar baboon species; and 3) apply a recently developed method currently used in humans for measuring multiple vitamin D metabolites as a panel to explore if/how these metabolites can inform us on vitamin D sufficiency. Serum samples from males of three baboon species in the wild: Papio anubis (olive baboon, dark exposed skin), P. cynocephalus (yellow baboon, brown exposed skin), and P. hamadryas (hamadryas baboon, pink exposed skin), were compared with vitamin D supplemented captive olive baboons with sun exposure. Liquid chromatography/tandem mass spectrometry (LC/MS/MS) measured vitamin D and its main metabolites. Cholecalciferol, 25 hydroxyvitamin D2&3 (25(OH)D2&3 ), and 24,25 dihydroxyvitamin D2&3 (24,25(OH)2 D2&3 ), showed significant differences by species. The levels of cholecalciferol due to supplements in the captive olive baboons did not convert to higher 25(OH)D3 while the wild olive baboons exhibited the lowest levels for both cholecalciferol and 25(OH)D3 . Further metabolic conversion of 25(OH)D3 to 24,25(OH)2 D3 indicated that all baboons had more similar conversion ratios and these were within the same range found for humans that are depicted as having adequate vitamin D levels. This study provided evidence that exposed skin color does influence vitamin D3 levels, with lower levels in darker skinned species, but these differences are eliminated in the downstream metabolite conversion indicating strong regulatory control.

Vitamin D3 repressed astrocyte activation following lipopolysaccharide stimulation in vitro and in neonatal rats

Vitamin D3 has been reported to be an immunity modulator and high levels of vitamin D3 are correlated with a decreased risk for developing diseases in the central nervous system. Astrocytes are important immune cells and contribute toward inflammation during neurological diseases. The vitamin D receptor has been reported to be expressed in astrocytes; however, the effect of vitamin D3 on astrocyte activation has not been studied. Here, we found that lipopolysaccharide stimulation in astrocytes could enhance the expression of vitamin D receptor and Cyp27B1, which encodes the enzyme for converting vitamin D3 into its active form. Vitamin D3 suppressed the expression of proinflammatory cytokines tumour necrosis factor-α, interleukin-1β, vascular endothelial growth factor, and also TLR4 in activated astrocytes. Astrocyte activation was further found to be suppressed after the administration of vitamin D3 in neonatal rats injected with lipopolysaccharide in vivo. We demonstrated the antiactivation effect of vitamin D3 in astrocytes after lipopolysaccharide stimulation. Considering the function of reactive astrocytes in augmenting inflammatory response in neurodegeneration and brain injury, the finding that vitamin D3 administration may inhibit astrocyte activation may be potentially useful for the treatment of central nervous system disorders.

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.

Metabolomic Analysis Reveals Vitamin D-induced Decrease in Polyol Pathway and Subtle Modulation of Glycolysis in HEK293T Cells

We combined ¹H NMR metabolomics with functional and molecular biochemical assays to describe the metabolic changes elicited by vitamin D in HEK293T, an embryonic proliferative cell line adapted to high-glucose concentrations. Activation of the polyol pathway, was the most important consequence of cell exposure to high glucose concentration, resembling cells exposed to hyperglycemia. Vitamin D induced alterations in HEK293T cells metabolism, including a decrease in sorbitol, glycine, glutamate, guanine. Vitamin D modulated glycolysis by increasing phosphoglycerate mutase and decreasing enolase activities, changing carbon fate without changing glucose consumption, lactate export and Krebs cycle. The decrease in sorbitol intracellular concentration seems to be related to vitamin D regulated redox homeostasis and protection against oxidative stress, and helped maintaining the high proliferative phenotype, supported by the decrease in glycine and guanine and orotate concentration and increase in choline and phosphocholine concentration. The decrease in orotate and guanine indicated an increased biosynthesis of purine and pyrimidines. Vitamin D elicited metabolic alteration without changing cellular proliferation and mitochondrial respiration, but reclaiming reductive power. Our study may contribute to the understanding of the metabolic mechanism of vitamin D upon exposure to hyperglycemia, suggesting a role of protection against oxidative stress.