Analysis of CYP27B1 in multiple sclerosis

Multiple Sclerosis: Lipids, Lymphocytes, and Vitamin D

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system. We review the two core MS features, myelin instability, fragmentation, and remyelination failure, and dominance of pathogenic CD4⁺ Th17 cells over protective CD4⁺ Treg cells. To better understand myelin pathology, we describe myelin biosynthesis, structure, and function, then highlight stearoyl-CoA desaturase (SCD) in nervonic acid biosynthesis and nervonic acid's contribution to myelin stability. Noting that vitamin D deficiency decreases SCD in the periphery, we propose it also decreases SCD in oligodendrocytes, disrupting the nervonic acid supply and causing myelin instability and fragmentation. To better understand the distorted Th17/Treg cell balance, we summarize Th17 cell contributions to MS pathogenesis, then highlight how 1,25-dihydroxyvitamin D₃ signaling from microglia to CD4⁺ T cells restores Treg cell dominance. This signaling rapidly increases flux through the methionine cycle, removing homocysteine, replenishing S-adenosyl-methionine, and improving epigenetic marking. Noting that DNA hypomethylation and inappropriate DRB1*1501 expression were observed in MS patient CD4⁺ T cells, we propose that vitamin D deficiency thwarts epigenetic downregulation of DRB1*1501 and Th17 cell signature genes, and upregulation of Treg cell signature genes, causing dysregulation within the CD4⁺ T cell compartment. We explain how obesity reduces vitamin D status, and how estrogen and vitamin D collaborate to promote Treg cell dominance in females. Finally, we discuss the implications of this new knowledge concerning myelin and the Th17/Treg cell balance, and advocate for efforts to address the global epidemics of obesity and vitamin D deficiency in the expectation of reducing the impact of MS.

Vitamin D3-mediated resistance to a multiple sclerosis model disease depends on myeloid cell 1,25-dihydroxyvitamin D3 synthesis and correlates with increased CD4+ T cell CTLA-4 expression

Microglial cell activation is the earliest biomarker of the inflammatory processes that cause central nervous system (CNS) lesions in multiple sclerosis. We hypothesized that 1,25-dihydroxyvitamin D₃ (1,25-(OH)₂D₃) production by activated microglia and macrophages in the CNS inhibits these inflammatory processes. To test this hypothesis, we targeted the Cyp27b1 gene specifically in myeloid cells, then analyzed the influence of disrupted myeloid cell 1,25-(OH)₂D₃ synthesis on vitamin D₃-mediated resistance to experimental autoimmune encephalomyelitis (EAE). Myeloid cell 1,25-(OH)₂D₃ synthesis was essential for vitamin D₃-mediated EAE resistance. Increased CTLA-4 expression in the CNS-infiltrating CD4⁺ Tconv and Treg cells and decreased splenic B cell CD86 expression correlated with resistance. These new data provide solid support for the view that vitamin D₃ reduces MS risk in part through a mechanism involving myeloid cell 1,25-(OH)₂D₃ production and CTLA-4 upregulation in CNS-infiltrating CD4⁺ T cells. We suggest that CTLA-4 serves as a vitamin D₃-regulated immunological checkpoint in multiple sclerosis prevention.

Role of cytochrome P450 polymorphisms and functions in development of ulcerative colitis

Cytochromes P450s (CYPs) are terminal enzymes in CYP dependent monooxygenases, which constitute a superfamily of enzymes catalysing the metabolism of both endogenous and exogenous substances. One of their main tasks is to facilitate the excretion of these substances and eliminate their toxicities in most phase 1 reactions. Endogenous substrates of CYPs include steroids, bile acids, eicosanoids, cholesterol, vitamin D and neurotransmitters. About 80% of currently used drugs and environmental chemicals comprise exogenous substrates for CYPs. Genetic polymorphisms of CYPs may affect the enzyme functions and have been reported to be associated with various diseases and adverse drug reactions among different populations. In this review, we discuss the role of some critical CYP isoforms (CYP1A1, CYP2D6, CYP2J2, CYP2R1, CYP3A5, CYP3A7, CYP4F3, CYP24A1, CYP26B1 and CYP27B1) in the pathogenesis or aetiology of ulcerative colitis concerning gene polymorphisms. In addition, their significance in metabolism concerning ulcerative colitis in patients is also discussed showing a clear underestimation in genetic studies performed so far.

Exonic variants of genes related to the vitamin D signaling pathway in the families of familial multiple sclerosis using whole-exome next generation sequencing

INTRODUCTION

Vitamin D (VD) deficiency has been associated with multiple sclerosis (MS) and other autoimmune diseases (AIDs). However, the effect of the genetics of VD on the risk of MS is subject to debate. This study focuses on genes linked to the VD signaling pathway in families with MS. The evaluation of gene variants in all the members of families could contribute to an additional knowledge on the information obtained from case-control studies that use nonrelated healthy people.

MATERIAL AND METHODS

We studied 94 individuals from 15 families including at least two patients with MS. We performed whole-exome next generation sequencing on all individuals and analyzed variants of the DHCR7, CYP2R1, CYP3A4, CYP27A1, GC, CYP27B1, LRP2, CUBN, DAB2, FCGR, RXR, VDR, CYP24A1, and PDIA3 genes. We also studied PTH, FGF23, METTL1, METTL21B, and the role of the linkage disequilibrium block on the long arm of chromosome 12, through analysis of the CDK4, TSFM, AGAP2, and AVIL genes. We compared patients with MS, other AIDs and unaffected members from different family types.

RESULTS

The study described the variants in the VD signaling pathway that appear in families with at least two patients with MS. Some infrequent variants were detected in these families, but no significant difference was observed between patients with MS and/or other AIDs and unaffected family members in the frequency of these variants. Variants previously associated with MS in the literature were not observed in these families or were distributed similarly in patients and unaffected family members.

CONCLUSION

The study of genes involved in the VD signaling pathway in families that include more than one patient with MS did not identify any variants that could explain the presence of the disease, suggesting that VD metabolism could probably play a role in MS more as an environmental factor rather than as a genetic factor. Our study also supports the analysis of cases and unaffected individuals within families in order to determine the influence of genetic factors.

1,25-Dihydroxyvitamin D3 increases the methionine cycle, CD4+ T cell DNA methylation and Helios+Foxp3+ T regulatory cells to reverse autoimmune neurodegenerative disease

We investigated how one calcitriol dose plus vitamin D₃ reverses experimental autoimmune encephalomyelitis (EAE), a multiple sclerosis model. This protocol rapidly increased CD4⁺ T cell Ikzf2 transcripts, Helios protein, and CD4⁺Helios⁺FoxP3⁺ T regulatory cells. It also rapidly increased CD4⁺ T cell Bhmt1 transcripts, betaine:homocysteine methyltransferase-1 (BHMT1) enzyme activity, and global DNA methylation. BHMT1 transmethylates homocysteine to replenish methionine. Targeting the Vdr gene in T cells decreased Ikzf2 and Bhmt1 gene expression, reduced DNA methylation, and elevated systemic homocysteine in mice with EAE. We hypothesize that calcitriol drives a transition from encephalitogenic CD4⁺ T cell to Treg cell dominance by upregulating Ikzf2 and Bhmt1, recycling homocysteine to methionine, reducing homocysteine toxicity, maintaining DNA methylation, and stabilizing CD4⁺Helios⁺FoxP3⁺Tregulatory cells. Conserved vitamin D-responsive element (VDRE)-type sequences in the Bhmt1 and Ikzf2 promoters, the universal need for methionine in epigenetic regulation, and betaine's protective effects in MTHFR-deficiency suggest similar regulatory mechanisms exist in humans.

Linkage analysis and whole exome sequencing identify a novel candidate gene in a Dutch multiple sclerosis family

BACKGROUND

Multiple sclerosis (MS) is a complex disease resulting from the joint effect of many genes. It has been speculated that rare variants might explain part of the missing heritability of MS.

OBJECTIVE

To identify rare coding genetic variants by analyzing a large MS pedigree with 11 affected individuals in several generations.

METHODS

Genome-wide linkage screen and whole exome sequencing (WES) were performed to identify novel coding variants in the shared region(s) and in the known 110 MS risk loci. The candidate variants were then assessed in 591 MS patients and 3169 controls.

RESULTS

Suggestive evidence for linkage was obtained to 7q11.22-q11.23. In WES data, a rare missense variant p.R183C in FKBP6 was identified that segregated with the disease in this family. The minor allele frequency was higher in an independent cohort of MS patients than in healthy controls (1.27% vs 0.95%), but not significant (odds ratio (OR) = 1.33 (95% confidence interval (CI): 0.8-2.4), p = 0.31).

CONCLUSION

The rare missense variant in FKBP6 was identified in a large Dutch MS family segregating with the disease. This association to MS was not found in an independent MS cohort. Overall, genome-wide studies in larger cohorts are needed to adequately investigate the role of rare variants in MS risk.

Vitamin D modulates different IL-17-secreting T cell subsets in multiple sclerosis patients

Vitamin D deficiency is an environmental risk factor for MS, a Th17 cell-mediated autoimmune disease that results in demyelination in the CNS. Therefore, we aimed to evaluate the ability of in vitro 1,25(OH)2D in modulating different Th17 cell subsets in MS patients in remission phase. In the present study, the production of Th17-related cytokines (IL-1β, IL-6, IL-17, IL-22), as well as GM-CSF, was significantly higher in cell cultures from MS patients than in healthy subjects (HS). The 1,25(OH)2D reduced all pro-inflammatory cytokines essayed, mainly those released from HS cell cultures. The proportion of both IL-17⁺IFN-γ⁺ (CD4⁺ and CD8⁺) T cells and IL-17⁺IFN-γ^-CD8⁺ T cells was positively related with neurological disorders, determined by EDSS score. The addition of 1,25(OH)2D reduced not only these pathogenic T cell subsets but elevated the percentage of IL-10-secreting conventional (FoxP3⁺CD25⁺CD127^-CD4⁺) and non-conventional (IL-17⁺) regulatory-like T cells. Taken together, the results indicate that the active form of vitamin D should benefit MS patients by attenuating the percentage of pathogenic T cells. This effect could be direct and/or indirect, by enhancing classical and non-classical regulatory T cells.

Meta-Analysis of Differential Connectivity in Gene Co-Expression Networks in Multiple Sclerosis

Differential gene expression analyses to investigate multiple sclerosis (MS) molecular pathogenesis cannot detect genes harboring genetic and/or epigenetic modifications that change the gene functions without affecting their expression. Differential co-expression network approaches may capture changes in functional interactions resulting from these alterations. We re-analyzed 595 mRNA arrays from publicly available datasets by studying changes in gene co-expression networks in MS and in response to interferon (IFN)-β treatment. Interestingly, MS networks show a reduced connectivity relative to the healthy condition, and the treatment activates the transcription of genes and increases their connectivity in MS patients. Importantly, the analysis of changes in gene connectivity in MS patients provides new evidence of association for genes already implicated in MS by single-nucleotide polymorphism studies and that do not show differential expression. This is the case of amiloride-sensitive cation channel 1 neuronal (ACCN1) that shows a reduced number of interacting partners in MS networks, and it is known for its role in synaptic transmission and central nervous system (CNS) development. Furthermore, our study confirms a deregulation of the vitamin D system: among the transcription factors that potentially regulate the deregulated genes, we find TCF3 and SP1 that are both involved in vitamin D3-induced p27Kip1 expression. Unveiling differential network properties allows us to gain systems-level insights into disease mechanisms and may suggest putative targets for the treatment.

The Association Between Genetic Polymorphism rs703842 in CYP27B1 and Multiple Sclerosis: A Meta-Analysis

Multiple sclerosis (MS) is the most frequent nontraumatic disabling neurological disease among young adults. Previous studies have examined the association of rs703842 in CYP27B1 with MS susceptibility, with inconsistent results reported.The objective of this study is to conduct a systematic literature search and perform meta-analyses to examine whether rs703842 is associated with MS risk.We searched potential literature in PubMed, Cochrane Library, Embase, Google Scholar, Web of Science, and HuGE by using the following inclusion criteria: studies were on human subjects; the studies were case-control studies; studies included subjects who had MS and those who did not have MS; and the studies provided genotype data for rs703842 for subjects who had and did not have MS, or provided odds ratios (ORs) and the 95% confidence intervals (CIs) for assessing the association of rs703842 with MS, or provided sufficient data for the calculation of OR and the 95% CI. We used random-effects models to calculate the OR as a measure of association. We used I to assess between-study heterogeneity, and a funnel plot and Egger test to assess publication bias.Seven studies published since 2008 met the eligibility criteria and were included in the meta-analyses. We found that the C allele was significantly associated with reduced MS susceptibility (OR = 0.88, 95% CI: 0.80-0.89; P < 0.0001). We also found significant association of rs703842 with MS risk using a dominant and a recessive model (both P < 0.0002). Our results remain unchanged if our meta-analysis was limited to studies that included only Caucasian participants (OR = 0.85, 95% CI: 0.80-0.90; P < 0.0001).Our study has several limitations: The sample size is limited; We were unable to control for some important confounding factors as data for individual participant were not available; and Most of the included studies focus on MS risk in Caucasian. As a result, we could not perform meta-analysis for assessing the relationship in other ethnic groups.In summary, we found that the genetic variant rs703842 in CYP27B1 is associated with MS risk in Caucasians. More studies with larger sample size that control for important confounding factors are needed to validate the findings from this study.

Vitamin D Actions on CD4(+) T Cells in Autoimmune Disease

This review summarizes and integrates research on vitamin D and CD4⁺ T-lymphocyte biology to develop new mechanistic insights into the molecular etiology of autoimmune disease. A deep understanding of molecular mechanisms relevant to gene–environment interactions is needed to deliver etiology-based autoimmune disease prevention and treatment strategies. Evidence linking sunlight, vitamin D, and the risk of multiple sclerosis and type 1 diabetes is summarized to develop the thesis that vitamin D is the environmental factor that most strongly influences autoimmune disease development. Evidence for CD4⁺ T-cell involvement in autoimmune disease pathogenesis and for paracrine calcitriol signaling to CD4⁺ T lymphocytes is summarized to support the thesis that calcitriol is sunlight’s main protective signal transducer in autoimmune disease risk. Animal modeling and human mechanistic data are summarized to support the view that vitamin D probably influences thymic negative selection, effector Th1 and Th17 pathogenesis and responsiveness to extrinsic cell death signals, FoxP3⁺CD4⁺ T-regulatory cell and CD4⁺ T-regulatory cell type 1 (Tr1) cell functions, and a Th1–Tr1 switch. The proposed Th1–Tr1 switch appears to bridge two stable, self-reinforcing immune states, pro- and anti-inflammatory, each with a characteristic gene regulatory network. The bi-stable switch would enable T cells to integrate signals from pathogens, hormones, cell–cell interactions, and soluble mediators and respond in a biologically appropriate manner. Finally, unanswered questions and potentially informative future research directions are highlighted to speed delivery of etiology-based strategies to reduce autoimmune disease.

Variants of CYP27B1 are associated with both multiple sclerosis and neuromyelitis optica patients in Han Chinese population

Multiple sclerosis (MS) and neuromyelitis optica (NMO) are chronic demyelinating diseases of the central nervous system (CNS). Recently, variants of vitamin D metabolizing genes, including rs12368653, rs10876994, rs118204009 and rs703842 in CYP27B1, and rs2248359 in CYP24A1 have been identified to be associated with the pathogenicity of MS in Caucasian populations. However, these results have not been replicated in Han Chinese population. Here we investigated the association of these variants with MS and NMO susceptibility in 149 MS patients, 110 NMO patients and 294 healthy controls using MassARRAY system and Sanger sequencing. We found that the frequencies of the A allele of rs703842 were higher in MS patients than controls (p=0.032), and statistical differences were observed in the genotypes of both rs703842 (p=0.013) and rs10876994 (p=0.001) between NMO patients and controls. In addition, we found difference in the genotype of rs12368653 between MS patients and controls (p=0.008). However, no difference was found in rs2248359 among these three groups. The reported rare mutation p.R389H (rs118204009) was not found in our study. In conclusion, our study suggested that variants of CYP27B1 were associated with both MS and NMO patients in Han Chinese population.