The genetics of clinical outcome in multiple sclerosis

Oligodeoxynucleotide IMT504: Effects on Central Nervous System Repair Following Demyelination

Multiple sclerosis (MS) is an immune-mediated central nervous system (CNS) disease characterized by demyelination resulting from oligodendrocyte loss and inflammation. Cuprizone (CPZ) administration experimentally replicates MS pattern-III lesions, generating an inflammatory response through microgliosis and astrogliosis. Potentially remyelinating agents include oligodeoxynucleotides (ODN) with a specific immunomodulatory sequence consisting of the active motif PyNTTTTGT. In this work, the remyelinating effects of ODN IMT504 were evaluated through immunohistochemistry and qPCR analyses in a rat CPZ-induced demyelination model. Subcutaneous IMT504 administration exacerbated the pro-inflammatory response to demyelination and accelerated the transition to an anti-inflammatory state. IMT504 reduced microgliosis in general and the number of phagocytic microglia in particular and expanded the population of oligodendroglial progenitor cells (OPCs), later reflected in an increase in mature oligodendrocytes. The intracranial injection of IMT504 and intravenous inoculation of IMT504-treated B lymphocytes rendered comparable results. Altogether, these findings unveil potentially beneficial properties of IMT504 in the regulation of neuroinflammation and oligodendrogenesis, which may aid the development of therapies for demyelinating diseases such as MS.

Seroprevalence of Toxoplasma gondii and Borrelia burgdorferi infections in patients with multiple sclerosis in Poland

Multiple sclerosis (MS) is a chronic, demyelinating disease of the central nervous system that affects mainly young people. It is believed that the autoimmune process observed in the pathogenesis of MS is influenced by a complex interaction between genetic and environmental factors, including infectious agents. The results of this study suggest the protective role of Toxoplasma gondii infections in MS. Interestingly, high Toxoplasma IgM seropositivity in MS patients receiving immunomodulatory drugs (IMDs) was identified. On the other hand, Borrelia infections seem to be positively associated with MS. Although the interpretation of our results is limited by the retrospective nature of the studies, the results strongly indicate that further experimental and clinical studies are needed to explain the role of infectious agents in the development and pathophysiological mechanisms of MS.

Demyelination-Remyelination in the Central Nervous System: Ligand-Dependent Participation of the Notch Signaling Pathway

Multiple sclerosis (MS) is an immune-mediated CNS disease mostly affecting young people. MS and other neurodegenerative and white matter disorders involve oligodendrocyte (OL) damage and demyelination. Therefore, elucidating the signaling pathways involved in the remyelination process through the maturation of OL progenitor cells (OPCs) may contribute to the development of new therapeutic approaches. In this context, this paper further characterizes toxic cuprizone (CPZ)-induced demyelination and spontaneous remyelination in rats and investigates the role of ligand-dependent Notch signaling activation along demyelination/remyelination both in vivo and in vitro. Toxic treatment generated an inflammatory response characterized by both microgliosis and astrogliosis. Interestingly, early demyelination revealed an increase in the proportion of Jagged1+/GFAP+ cells, which correlated with an increase in Jagged1 transcript and concomitant Jagged1-driven Notch signaling activation, particularly in NG2+ OPCs, in both the corpus callosum (CC) and subventricular zone (SVZ). The onset of remyelination then exhibited an increase in the proportion of F3/contactin+/NG2+ cells, which correlated with an increase in F3/contactin transcript during ongoing remyelination in the CC. Moreover, neurosphere cultures revealed that neural progenitor cells (NPCs) present in the brain SVZ of CPZ-treated rats recapitulate in vitro the mechanisms underlying the response to toxic injury observed in vivo, compensating for mature OL loss. Altogether, the present results offer strong evidence of cell-type and ligand-specific Notch signaling activation and its time- and area-dependent participation in toxic demyelination and spontaneous remyelination.

Gene variants of adhesion molecules predispose to MS: A case-control study

Objective

To examine the effect of variants in genes encoding molecules that are implicated in leukocyte trafficking into the CNS on the development of MS.

Methods

A total of 389 Greek MS cases and 336 controls were recruited by 3 MS centers in Cyprus and Greece. In total, 147 tagging single nucleotide polymorphisms across 9 genes encoding for P-selectin (SELP), integrins (ITGA4, ITGB1, and ITGB7), adhesion molecules (ICAM1, VCAM1, and MADCAM1), fibronectin 1 (FN1), and osteopontin (SPP1) were genotyped. The clinical end point of the study was diagnosis of MS according to the 2005 revised McDonald criteria. Permutation analysis was used for adjusting for multiple comparisons.

Results

Overall, 21 variants across SELP, ITGA4, ITGB1, ICAM1, VCAM1, MADCAM1, FN1, and SSP1 genes were each associated with MS (p _perm < 0.05). The most significant were rs3917779 and rs2076074 (SELP), rs6721763 (ITGA4), and rs1250258 (FN1), all with a permutation p value of less than 1e-004.

Conclusions

The current study provides preliminary evidence that variants across genes encoding adhesion molecules, responsible for lymphocyte adhesion and trafficking within the CNS, are implicated in the risk of developing MS.

[Association analysis of cytokine receptors' genes polymorphisms with clinical features of multiple sclerosis]

AIM

To study the association of polymorphisms in the IL2RA and TNFRSF1A genes with severity and early clinical manifestations of remitted multiple sclerosis (MS).

MATERIAL AND METHODS

Five hundred and eight patients of Russian ethnicity with bout-onset MS were genotyped for IL7RA (rs6897932), IL2RA (rs2104286) and TNFRSF1A (rs1800693) polymorphisms. Association analysis of the gene variants with disease severity, variants of MS manifestation, and first remission duration was performed.

RESULTS AND CONCLUSION

Dividing the MS patients by disease severity, estimated with the MSSS, we found a significant increase in the TNFRSF1A*T/T genotype carriage in patients with milder MS course (MSSS≤3), and, respectively, in the TNFRSF1A*C allele carriage in patients with moderate to severe MS (MSSS> 3). Dividing the MS patients into two groups according to their MS manifestation variants, we revealed a significant increase in the TNFRSF1A*T allele carriage in patients with favorable variants of MS manifestation (optic neuritis or sensory disturbances), and of the TNFRSF1A*C/C genotype in patients with unfavorable variants (motor disorders, brain stem disorders, impaired coordination, pelvic disorders, mental disorders or polysymptomatic onset). No associations with first remission duration were observed. Multi-locus analysis to search for allelic combinations associated with the studied clinical features of MS was applied. In this analysis, a polymorphic variant of CTLA4 gene (rs231775), for which we have previously reported the association of the CTLA4*G allele with short first remission (less than 1 year), was also included. The carriage of biallelic combination (CTLA4*G + TNFRSF1A*C) was associated with short first remission more significantly than the carriage of CTLA4*G by itself. One more biallelic combination associated with short first remission (CTLA4*G/G + IL7RA*T), was identified. No other biallelic combinations significantly associated with the clinical features studied were observed.

Gene variants of adhesion molecules act as modifiers of disease severity in MS

Objective:

To assess the potential effect of variants in genes encoding molecules that are implicated in leukocyte trafficking into the CNS on the clinical phenotype of multiple sclerosis (MS).

Methods:

A total of 389 Greek MS cases and 336 controls were recruited in 3 MS centers from Cyprus and Greece. We genotyped 147 tagging single nucleotide polymorphisms (SNPs) in 9 genes encoding for P-selectin (SELP), integrins (ITGA4, ITGB1, and ITGB7), adhesion molecules (ICAM1, VCAM1, and MADCAM1), fibronectin 1 (FN1), and osteopontin (SPP1) involved in lymphocyte adhesion and trafficking into the CNS. Clinical end points of the study were age at MS onset and MS severity as measured by the Multiple Sclerosis Severity Score. Permutation testing was applied to all analyses.

Results:

SNPs rs6721763 of the ITGA4 and rs6532040 of the SPP1 were found to significantly influence disease severity (permutation p values: 3.00e-06 and 0.009884, respectively). SNP rs1250249 of the FN1 had a dose-dependent effect on age at disease onset (permutation p value: 0.0002).

Conclusions:

This study provides evidence implicating variants encoding adhesion molecules, responsible for lymphocyte adhesion and trafficking within the CNS, as modifiers of MS disease severity. These genetic biomarkers, which can be available at the time of diagnosis, may be used to assess the biological aggressiveness of the disease and thus guide decisions on treatment.

A genetic basis for multiple sclerosis severity: Red herring or real?

Multiple Sclerosis (MS) is an autoimmune degenerative disease of the central nervous system, characterized by multifocal demyelination and neurodegeneration. The genetic architecture of MS is complex, where genetic risk has been attributed to over 100 polymorphic loci each with small odds ratios. MS is a highly heterogeneous disease with numerous clinical and paraclinical endophenotypes. To-date, no genetic variant has been associated with clinical outcome, however, evidence exists that MS outcomes, like risk, are to an extent also controlled by genetic variation. Here we summarise the current evidence for genetic determination of disease outcomes and make recommendations for future research directions.

The association of IL-18 gene promoter polymorphisms and the levels of serum IL-18 on the risk of multiple sclerosis

OBJECTIVES

Multiple sclerosis is an inflammatory condition of the central nervous system whose etiology is influenced by immunologic, genetic, and environmental factors. Aim of the present study was to determine if any relation exists between IL-18 -137C/G and -607C/A gene promoter polymorphisms on the individual susceptibility of multiple sclerosis and also to investigate the possible effect of IL-18 activity regarding this kind of polymorphism and MS.

PATIENTS AND METHODS

113 patients with clinically definite MS and 135 ethnically-matched controls were participated in this study. IL-18 -137C/G and -607C/A gene promoter polymorphisms were analyzed by Sequence Specific Polymerase Chain Reaction (SS-PCR), while levels of serum IL-18 were measured by Enzyme Linked Immunoassay Assay (ELISA) in patients with MS and healthy controls.

RESULTS

Our results showed that the IL-18 -607AA genotype indicated 6 times higher risk in the development of MS (OR=6.883; 3.17-14.96; p<0.001). According to our findings, smoking seems to be an important confounding factor in MS patients with carrying IL-18 -607 AA and CA+AA genotypes. However, no meaningful association was found with IL-18 -137C/G gene promoter polymorphism.

CONCLUSION

In conclusion, we suggest that IL-18 -607C/A gene promoter polymorphism is a major genetic factor for determining individual susceptibility to MS, where smoking status also increases the risk of MS.

Epigenetic modifications of Dexras 1 along the nNOS pathway in an animal model of multiple sclerosis

The development of multiple sclerosis, a major neurodegenerative disease, is due to both genetic and environmental factors that might trigger aberrant epigenetic changes of the genome. In this study, we analysed global DNA methylation in the brain of mice upon induction of experimental autoimmune encephalomyelitis (EAE), and the effect of environmental enrichment (EE). We demonstrate that global DNA methylation decreased in the striatum, but not in the cortex, of EAE mice compared to healthy controls, in particular in neuronal nitric oxide synthase (nNOS)-positive interneurons of this brain area. Also, in the striatum but again not in the cortex, decreased DNA methylation of the nNOS downstream effector, dexamethasone-induced Ras protein 1 (Dexras 1), was observed in EAE mice, and was paralleled by an increase in its mRNA. Interestingly, EE was able to revert EAE effects on mRNA expression and DNA methylation levels of Dexras 1 and reduced gene expression of nNOS and 5-lipoxygenase (Alox5). Conversely, interleukin-1β (IL-1β) gene expression was found up-regulated in EAE mice compared to controls and was not affected by EE. Taken together, these data demonstrate an unprecedented epigenetic modulation of nNOS-signaling in the pathogenesis of multiple sclerosis, and show that EE can specifically revert EAE effects on Dexras 1 along this pathway.

HLA-DRα1-mMOG-35-55 treatment of experimental autoimmune encephalomyelitis reduces CNS inflammation, enhances M2 macrophage frequency, and promotes neuroprotection

Background

DRα1-mouse(m)MOG-35-55, a novel construct developed in our laboratory as a simpler and potentially less immunogenic alternative to two-domain class II constructs, was shown previously to target the MIF/CD74 pathway and to reverse clinical and histological signs of experimental autoimmune encephalomyelitis (EAE) in DR*1501-Tg mice in a manner similar to the parent DR2β1-containing construct.

Methods

In order to determine whether DRα1-mMOG-35-55 could treat EAE in major histocompatibility complex (MHC)-mismatched mice and to evaluate the treatment effect on central nervous system (CNS) inflammation, C57BL/6 mice were treated with DRα1-mMOG-35-55. In addition, gene expression profile was analyzed in spinal cords of EAE DR*1501-Tg mice that were treated with DRα1-mMOG-35-55.

Results

We here demonstrate that DRα1-mMOG-35-55 could effectively treat EAE in MHC-mismatched C57BL/6 mice by reducing CNS inflammation, potentially mediated in part through an increased frequency of M2 monocytes in the spinal cord. Microarray analysis of spinal cord tissue from DRα1-mMOG-35-55-treated vs. vehicle control mice with EAE revealed decreased expression of a large number of pro-inflammatory genes including CD74, NLRP3, and IL-1β and increased expression of genes involved in myelin repair (MBP) and neuroregeneration (HUWE1).

Conclusion

These findings indicate that the DRα1-mMOG-35-55 construct retains therapeutic, anti-inflammatory, and neuroprotective activities during treatment of EAE across MHC disparate barriers.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-015-0342-4) contains supplementary material, which is available to authorized users.

Apolipoproteins are associated with new MRI lesions and deep grey matter atrophy in clinically isolated syndromes

OBJECTIVES

There is increasing evidence that serum lipoprotein cholesterol biomarkers are associated with disease progression in clinically isolated syndromes (CIS). Apolipoproteins (Apo) are recognition ligands that mediate the physiological interactions of cholesterol-containing lipoproteins. The objective of this study was to investigate whether serum Apo levels are associated with CIS disease progression.

METHODS

ApoB, ApoAI, ApoAII, ApoE and lipoprotein (a) (Lpa) levels were measured in serum samples obtained prior to the start of treatment from 181 CIS patients (123 women, 58 men, 68% women; mean age: 28.1±SD 8.1 years). All patients were treated with intramuscular interferon-β as part of the prospective study. Clinical and MRI assessments were obtained at baseline, 6, 12 and 24 months after start of interferon-β treatment.

RESULTS

Greater ApoB levels were associated with increased number of new T2 lesions (p<0.001) and increased number of new or enlarging T2 lesions (p<0.001) over 2 years. Each 10 mg/dL of greater baseline ApoB is associated with a 16% increase in the number of new T2 lesions over 2 years. ApoAI, ApoAII, ApoE and Lpa were not associated with T2 lesions. Greater ApoE levels were associated with greater deep grey matter atrophy (partial correlation rp=-0.28, p<0.001). Each 1 mg/dL increment in ApoE levels was associated with a 1% increase in deep grey matter atrophy over 2 years.

CONCLUSIONS

Serum ApoB levels are associated with new lesion accumulation whereas ApoE levels are associated with deep grey matter atrophy in high risk CIS patients treated with interferon β-1a.

NQO1 gene rs1800566 variant is not associated with risk for multiple sclerosis

BACKGROUND

A possible role of oxidative stress in the pathogenesis of multiple sclerosis (MS) and in experimental autoimmune encephalomyelitis has been suggested. The detoxification enzyme NAD(P)H dehydrogenase, quinone 1 (NQO1) has been found up-regulated in MS lesions. A previous report described an association between the SNP rs1800566 in the NQO1 gene and the risk for MS in the Greek population. The aim of this study was to replicate a possible influence of the. SNP rs1800566 in the NQO1 gene in the risk for MS in the Spanish Caucasian population.

METHODS

We analyzed allelic and genotypic frequency of NQO1 rs1800566 in 290 patients with MS and 310 healthy controls, using TaqMan Assays.

RESULTS

NQO1 rs1800566 allelic and genotypic frequencies did not differ significantly between MS patients and controls, and were unrelated with age of onset of MS, gender, and clinical type of MS.

CONCLUSIONS

Our results indicate that NQO1 rs1800566 does not have an effect on MS disease risk.

Interactions of serum cholesterol with anti-herpesvirus responses affect disease progression in clinically isolated syndromes

OBJECTIVES

To investigate whether anti-herpesvirus antibodies are associated with serum cholesterol profiles in clinically isolated syndromes (CIS).

METHODS

Pre-treatment serum samples from 118 high-risk CIS patients were analyzed for IgG antibodies against cytomegalovirus (anti-CMV), Epstein Barr virus (EBV) viral capsid antigen (VCA) and EBV nuclear antigen-1 (EBNA-1). A lipid profile consisting of high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and total cholesterol (TC) was obtained. Clinical and MRI assessments were obtained at baseline, 6, 12, and 24 months after start of interferon-beta treatment.

RESULTS

The study included 118 CIS patients (77 females, 41 males, 65.3% female; mean age: 28.1±SD 8.1 years). Anti-EBV EBNA-1 antibody levels were associated with LDL-C (p=0.009) and TC (p=0.008) levels. Anti-CMV positivity status was associated with reduced time to relapse (p=0.006) and the greater number of relapses (p=0.009) in patients with high HDL-C. Anti-EBV VCA antibody levels were associated with greater number of new T2 lesions (p=0.002) and with increased brain atrophy (p<0.001) in patients with high LDL-C.

CONCLUSIONS

Our results indicate that higher levels of anti-EBV EBNA-1 antibodies are associated with higher LDL-C and TC levels. Anti-CMV positive individuals have greater disease progression in the presence of higher HDL-C levels. Individuals with higher levels of anti-EBV VCA antibodies have greater progression on MRI measures in the presence of higher LDL-C.

MAPT gene rs1052553 variant is not associated with the risk for multiple sclerosis

BACKGROUND/OBJECTIVES

Some experimental data suggest a possible role of tau protein in the pathogenesis of multiple sclerosis (MS) and in experimental autoimmune encephalomyelitis. The aim of this study was to investigate a possible influence of the SNP rs1052553 in the MAPT gene in the risk for relapsing bout onset (relapsing-remitting and secondary progressive) MS.

METHODS

We analyzed the allelic and genotype frequency of MAPT rs1052553, which has been associated with some neurodegenerative diseases, in 259 patients with relapsing bout onset MS and 291 healthy controls, using TaqMan Assays.

RESULTS

MAPT rs1052553 allelic and genotype frequencies did not differ significantly between relapsing bout onset MS patients and controls, and were unrelated with the age of onset of MS or gender.

CONCLUSIONS

These results suggest that MAPT rs1052553 polymorphism is not related with the risk for relapsing bout onset MS.

Histamine H(3) receptor integrates peripheral inflammatory signals in the neurogenic control of immune responses and autoimmune disease susceptibility

Histamine H₃ receptor (Hrh3/H₃R) is primarily expressed by neurons in the central nervous system (CNS) where it functions as a presynaptic inhibitory autoreceptor and heteroreceptor. Previously, we identified an H₃R-mediated central component in susceptibility to experimental allergic encephalomyelitis (EAE), the principal autoimmune model of multiple sclerosis (MS), related to neurogenic control of blood brain barrier permeability and peripheral T cell effector responses. Furthermore, we identified Hrh3 as a positional candidate for the EAE susceptibility locus Eae8. Here, we characterize Hrh3 polymorphisms between EAE-susceptible and resistant SJL and B10.S mice, respectively, and show that Hrh3 isoform expression in the CNS is differentially regulated by acute peripheral inflammatory stimuli in an allele-specific fashion. Next, we show that Hrh3 is not expressed in any subpopulations of the immune compartment, and that secondary lymphoid tissue is anatomically poised to be regulated by central H₃R signaling. Accordingly, using transcriptome analysis, we show that, inflammatory stimuli elicit unique transcriptional profiles in the lymph nodes of H₃RKO mice compared to WT mice, which is indicative of negative regulation of peripheral immune responses by central H₃R signaling. These results further support a functional link between the neurogenic control of T cell responses and susceptibility to CNS autoimmune disease coincident with acute and/or chronic peripheral inflammation. Pharmacological targeting of H₃R may therefore be useful in preventing the development and formation of new lesions in MS, thereby limiting disease progression.

Vitamin D3 receptor ( VDR ) gene rs2228570 (Fok1) and rs731236 (Taq1) variants are not associated with the risk for multiple sclerosis: results of a new study and a meta-analysis

Background

Some epidemiological, genetic, and experimental data suggest a possible role of vitamin D in the pathogenesis of multiple sclerosis (MS) and in experimental autoimmune encephalomyelitis. Data on the possible contribution of several single nucleotide polymorphisms (SNP) in the vitamin D receptor (VDR) gene to the risk for MS are controversial. Several studies suggested an interaction between some SNPs in the VDR gene and HLADRB1*1501 in the risk for MS.

Objectives

The aim of this study was to investigate a possible influence of the SNPs rs2228570 and rs731236 in the VDR gene in the risk for MS. A secondary objective was to address the possible interactions between VDR genes and HLADRB1*1501.

Methods

We analyzed the allelic and genotype frequency of VDR rs2228570, rs731236, and HLADRB1*1501 (rs3135388) in 303 patients with MS and 310 healthy controls, using TaqMan Assays. We also conducted a meta-analysis, that was carried out by using the software Meta-Disc 1.1.1 (http://www.hrc.es/investigacion/metadisc.html; Unit of Clinical Statistics, Hospital Ramón y Cajal, Madrid, Spain). Heterogeneity between studies in terms of degree of association was tested using the Q-statistic.

Results

VDR rs2228570 and rs731236 allelic and genotype frequencies did not differ significantly between MS patients and controls, and were unrelated with the age of onset of MS, gender, and course of MS. HLADRB1*1501 showed a high association with the risk of developing MS 4.76(95% C.I.  = 3.14–7.27; p<0.0001). The meta-analysis, after excluding data of one study that was responsible of heterogeneity for rs731236 polymorphism, showed lack of relation of both SNPs with the risk for MS. HLADRB1*1501 showed lack of interaction with VDR rs2228570 and rs731236 in increasing MS risk.

Conclusions

These results suggest that VDR rs2228570 and rs731236 polymorphisms are not related with the risk for MS, and did not confirm interaction between these VDR SNPs and HLADRB1 in the risk for MS.

LINGO1 rs9652490 and rs11856808 polymorphisms are not associated with risk for multiple sclerosis

BACKGROUND

Some recent experimental data suggest a possible role of LINGO-1 in the pathogenesis of multiple sclerosis (MS). In an attempt to identify genetic biomarkers related to MS susceptibility, we genotyped two common SNPs in the LINGO1 gene which have been associated to other neurological conditions, in patients with MS and in healthy subjects. These SNPs are linked to several SNPs within the LINGO1 gene, especially in individuals of Oriental or Caucasian descent.

METHODS

We analyzed the allelic and genotype frequency of two LINGO1 variants (rs9652490 and rs11856808) in 293 patients with MS and 318 healthy controls, using KASPar assays.

RESULTS

LINGO1 rs9652490 and rs11856808 allelic and genotype frequencies did not differ significantly between MS patients and controls. The minor allele frequencies for rs9652490 were 0.171 (95% CI = 0.140-0.201) and 0.167 (95% CI = 0.138-0.196 for cases and controls respectively (p = 0.853). For rs11856808 the minor allele frequencies were 0.317 (95% CI = 0.280-0.355) and 0.310 (95% CI = 0.274-0.346) for cases and controls, respectively (p = 0.773). Allele and genotype frequencies were unrelated with the age of onset of MS, gender, and clinical course of MS. In addition, haplotype analyses did not reveal any putative risk related to haplotypes.

CONCLUSIONS

These results suggest that LINGO1 rs9652490 and rs11856808 polymorphisms are not related with risk for MS. This study adds to other published evidence indicating that, to date, the LINGO1 SNPs studied here could be useful risk biomarkers of developing essential tremor, but not other movement disorders.

Casting light on multiple sclerosis heterogeneity: the role of HLA-DRB1 on spinal cord pathology

Clinical heterogeneity in multiple sclerosis is the rule. Evidence suggests that HLA-DRB1*15 may play a role in clinical outcome. Spinal cord pathology is common and contributes significantly to disability in the disease. The influence of HLA-DRB1*15 on multiple sclerosis spinal cord pathology is unknown. A post-mortem cohort of pathologically confirmed cases with multiple sclerosis (n = 108, 34 males) with fresh frozen material available for genetic analyses and fixed material for pathology was used. HLA-DRB1 alleles were genotyped to select a subset of age- and sex-matched HLA-DRB1*15-positive (n = 21) and negative (n = 26) cases for detailed pathological analyses. For each case, transverse sections from three spinal cord levels (cervical, thoracic and lumbar) were stained for myelin, axons and inflammation. The influence of HLA-DRB1*15 on pathological outcome measures was evaluated. Carriage of HLA-DRB1*15 significantly increased the extent of demyelination (global measure 15+: 23.7% versus 15-: 12.16%, P = 0.004), parenchymal (cervical, P < 0.01; thoracic, P < 0.05; lumbar, P < 0.01) and lesional inflammation (border, P = 0.001; periplaque white matter, P < 0.05) in the multiple sclerosis spinal cord. HLA-DRB1*15 influenced demyelination through controlling the extent of parenchymal inflammation. Meningeal inflammation correlated significantly with small fibre axonal loss in the lumbar spinal cord (r = -0.832, P = 0.003) only in HLA-DRB1*15-positive cases. HLA-DRB1*15 significantly influences pathology in the multiple sclerosis spinal cord. This study casts light on the role of HLA-DRB1*15 in disease outcome and highlights the powerful approach of using microscopic pathology to clarify the way in which genes and clinical phenotypes of neurological diseases are linked.

Allelic variants in TLR10 gene may influence bilateral affectation and clinical course of Meniere's disease

Toll-like receptors trigger the innate immune response by activating various cell types such us macrophages and lymphocytes. We genotyped SNV of TLR3, TRL7, TLR8 and TLR10 in 863 Spanish and 150 Italian patients with Meniere's disease (MD) and 1,013 controls by using Taqman assays. Real-Time qPCR was used to measure the expression level of TLR10 in peripheral blood leukocytes. The overall dataset showed that the C allele and the CC genotype of rs11096955 in TLR10 gene were more commonly observed in controls than patients (corrected p = 1 × 10(-3), OR = 0.68 [95 % confidence interval, 0.54-0.84] for CC genotype; corrected p = 1.5 × 10(-5), OR = 0.75 [0.66-0.85] for allele C). Moreover, the CC genotype was more frequent in patients with uni- (19 %) than bilateral sensorineural hearing loss (SNHL) (13 %). Logistic regression demonstrated that the time since the onset of MD, Tumarkin crises, hearing stage and rs11096955 were independent factors influencing the risk of bilateral SNHL. In addition, rs11096955 influenced hearing loss progression in patients with bilateral MD. No change in expression of TLR10 was observed according to CC, CA or AA genotypes. Our data suggest that allelic variants of TLR10 gene may influence the susceptibility and time-course of hearing loss of MD in the European population.

Functional variants of MIF, INFG and TFNA genes are not associated with disease susceptibility or hearing loss progression in patients with Ménière's disease

Variability in acute immune response genes could determine susceptibility or prognosis for Ménière's disease (MD). The cytokines tumor necrosis factor α (TNFα), macrophage migration inhibitory factor (MIF) and interferon γ (INFγ) are proinflammatory cytokines of the innate immune response. These cytokines mediate inflammation and have been previously associated with the inflammatory process in several autoimmune diseases. We investigated the association between functional allelic variants of MIF (rs35688089), IFNG (rs2234688) and TNFA (rs1800629) in patients with MD. In addition to testing these variants for an association with disease, we also tested for an association with clinical aspects of disease progression, such as persistence of vertigo and the sensorineural hearing loss. A total of 580 patients with diagnosis of definite MD, according to the diagnostic scale of the American Academy of Otolaryngology-Head and Neck Surgery, and 552 healthy controls were included. DNA samples from a set of 291 American patients were used to confirm the results obtained in the MIF gene in our Spanish cohort. Although we found a significant association with the allele containing five repeats of CATT within the MIF gene in patients with MD in the Spanish cohort [corrected p = 0.008, OR = 0.69 (95 % CI, 0.54-0.88)], this finding could not be replicated in the American set. Moreover, no genetic associations for variants in either the TNFA or IFNG genes and MD were found. These results support the conclusion that functional variants of MIF, INFG, and TFNA genes are not associated with disease susceptibility or hearing loss progression in patients with MD.

Estimating the proportion of variation in susceptibility to multiple sclerosis captured by common SNPs

Multiple sclerosis (MS) is a complex disease with underlying genetic and environmental factors. Although the contribution of alleles within the major histocompatibility complex (MHC) are known to exert strong effects on MS risk, much remains to be learned about the contributions of loci with more modest effects identified by genome-wide association studies (GWASs), as well as loci that remain undiscovered. We use a recently developed method to estimate the proportion of variance in disease liability explained by 475,806 single nucleotide polymorphisms (SNPs) genotyped in 1,854 MS cases and 5,164 controls. We reveal that ~30% of MS genetic liability is explained by SNPs in this dataset, the majority of which is accounted for by common variants. These results suggest that the unaccounted for proportion could be explained by variants that are in imperfect linkage disequilibrium with common GWAS SNPs, highlighting the potential importance of rare variants in the susceptibility to MS.

Association of SNPs rs6498169 and rs10984447 with multiple sclerosis in Saudi patients: a model of the usefulness of familial aggregates in identifying genetic linkage in a multifactorial disease

OBJECTIVE

Genome-Wide association studies (GWAS) showed an association between subset of single-nucleotide polymorphism (SNPs) and multiple sclerosis. Our study aims to study this association in Saudi familial multiple sclerosis patients.

METHODS

Four subject groups were used in this study: sporadic MS (MS patients without family history), FMS (MS patients who have at least one family member diagnosed with MS), related controls (relatives of FMS patients who appear to be free of the disease) and independent controls (healthy volunteers). Subjects were genotyped for 15 SNPs. The variation in the genotype distribution was analyzed across study groups by using logistic regression.

RESULTS

342 subjects were included. 99 were in the sporadic MS group, 22 were FMS, 89 were related control, and 132 were independent control. SNPS rs3135388, rs7577363, rs1321172, rs6897932, rs6498169, rs12487066, and rs4763655were associated with MS when MS and independent control groups were compared. Same SNPS were identified but with stronger association when the FMS and independent control groups were compared. Finally, when the patients and the controls were selected from a much more homogenous genetic pool from which it would be expected that only SNPs highly linked to MS would persist, only two SNPs rs6498169[OR 4.26, CI (1.17 - 15.51)];, and rs10984447 [OR 13.63, CI(1.54, 120.83) ][were associated with MS.

CONCLUSIONS

Our results suggest that using a more homogenous genetic pool of cases and controls could help to identify the most significant MS-associated SNPs. Our finding is in agreement with other studies including larger sample size and more diverse populations.

Natural history of multiple sclerosis: early prognostic factors

Multiple sclerosis is a heterogeneous disease, and predicting its course is difficult at the individual level. In this article, clinical, demographic, and additional features that are associated with the risk of relapses and of intermediate-term disability are reviewed.

CCR5Δ32 Polymorphism Associated with a Slower Rate Disease Progression in a Cohort of RR-MS Sicilian Patients

Multiple sclerosis (MS) disease is carried through inflammatory and degenerative stages. Based on clinical feaures, it can be subdivided into three groups: relapsing-remitting MS, secondary progressive MS, and primary progressive MS. Multiple sclerosis has a multifactorial etiology with an interplay of genetic predisposition, environmental factors, and autoimmune inflammatory mechanism in which play a key role CC-chemokines and its receptors. In this paper, we studied the frequency of CCR5 gene Δ32 allele in a cohort of Sicilian RR-MS patients comparing with general Sicilian population. Also, we evaluate the association between this commonly polymorphism and disability development and age of disease onset in the same cohort. Our results show that presence of CCR5Δ32 is significantly associated with expanded disability status scale score (EDSS) but not with age of disease onset.

HLA-DRB1: genetic susceptibility and disability progression in a Spanish multiple sclerosis population

BACKGROUND AND OBJECTIVE

The association of HLA-DRB1*15 with susceptibility to multiple sclerosis (MS) has been consistently reported although its effect on the clinical phenotype is still controversial. The objectives of this study are to investigate the influence of the HLA-DRB1 alleles on the genetic susceptibility to MS and to study their impact on disability progression in a Spanish population.

METHODS

HLA-DRB1 typing was performed by PCR-SSP in 380 patients with sporadic MS and 1088 unrelated healthy controls. Allelic frequencies were compared between groups. We studied the correlation between the different alleles and the progression of MS.

RESULTS

The HLA-DRB1*15 allele in patients with MS had a statistically significant higher frequency when compared with controls (18.9% in patients vs. 10.1% in controls, Odds ratio (OR)=2.07, 95% CI=1.64-2.60, P<0.001). In the univariate analysis, the DRB1*01 and DRB1*04 alleles were associated with a worse prognosis when considering the time to reach an EDSS of 6, whereas the DRB1*03 was correlated with a better outcome. In the multivariate analysis, the alleles*01 and *04 were demonstrated to be independent factors to have a worse prognosis.

CONCLUSIONS

HLA-DRB1*15 is associated with MS when comparing patients with unrelated healthy controls in a Spanish population. The HLA-DRB1*01 and HLA-DRB1*04 alleles are related to a worse prognosis when considering the time taken to reach severe disability.

HLA (A-B-C and -DRB1) alleles and brain MRI changes in multiple sclerosis: a longitudinal study

Several major histocompatibility complex (MHC) alleles have been postulated to influence the susceptibility to multiple sclerosis (MS), as well as its clinical/radiological course. In this longitudinal observation, we further explored the impact of human leukocyte antigen (HLA) class I/II alleles on MS outcomes, and we tested the hypothesis that HLA DRB1*1501 might uncover different strata of MS subjects harboring distinct MHC allele associations with magnetic resonance imaging (MRI) measures. Five hundred eighteen MS patients with two-digit HLA typing and at least one brain MRI were recruited for the study. T2-weighted hyperintense lesion volume (T2LV) and brain parenchymal fraction (BPF) were acquired at each time point. The association between allele count and MRI values was determined using linear regression modeling controlling for age, disease duration and gender. Analyses were also stratified by the presence/absence of HLA DRB1*1501. HLA DRB1*04 was associated with higher T2LV (P=0.006); after stratification, its significance remained only in the presence of HLA DRB1*1501 (P=0.012). The negative effect of HLA DRB1*14 on T2LV was exerted in DRB1*1501-negative group (P=0.012). Longitudinal analysis showed that HLA DRB1*10 was significantly protective on T2LV accrual in the presence of HLA DRB1*1501 (P=0.002). Although the majority of our results did not withstand multiple comparison correction, the differential impact of several HLA alleles in the presence/absence of HLA DRB1*1501 suggests that they may interact in determining the different phenotypic expressions of MS.

Familial multiple sclerosis: does consanguinity have a role?

Parental consanguinity (PC) may be a risk factor for familial multiple sclerosis (FMS) throughout inbred communities. The objective of this report was to estimate prevalence of FMS and rate of PC among FMS versus non-FMS patients. All Saudi MS patients were identified from our registry. The history of PC was analyzed as a case-control study. In total 141 MS patients were identified. Of these, 30 (21%) reported having at least one affected relative, 37.6% reported PC and 16% presented first-degree PC. In addition, FMS patients were more likely than non-FMS patients to report PC. In conclusion, FMS is prevalent among Saudi MS patients. MS patients with a history of PC were more likely to have FMS, suggesting a potential role of consanguinity.

HLA-DPB1 0501 is associated with susceptibility to anti-aquaporin-4 antibodies positive neuromyelitis optica in southern Han Chinese

OBJECTIVES

To analyze the role of HLA-DRB1 and -DPB1 alleles in the pathogenesis of neuromyelitis optica (NMO) and multiple sclerosis in Southern Han Chinese.

METHODS

Thirty serum anti-aquaporin 4 antibodies (AQP4-Ab)-positive NMO patients, 53 conventional multiple sclerosis (C-MS) patients, and 93 controls (CTLs) were enrolled. The HLA-DRB1 and -DPB1 alleles of the subjects were determined by sequencing-based typing (SBT).

RESULTS

The frequency of the DRB1 0901 was lower in NMO patients than in CTLs (P(uncorr)=0.022, OR: 0.194, 95% CI: 0.043-0.876), and DRB1 1602 was higher in NMO patients than in C-MS (P(uncorr)=0.038, OR: 3.491, 95% CI: 1.024-11.896) and CTLs (P(uncorr)=0.051, OR: 2.711, 95% CI: 0.971-7.556). The frequency of DPB1 0501 was significant higher in NMO patients than in C-MS (P(uncorr)=0.018, OR: 4.629, 95% CI: 1.235-17.350) and CTLs (P(uncorr)=0.001, P(corr)=0.022, OR: 7.096, 95% CI: 2.011-25.044).

CONCLUSIONS

DPB1 0501 correlates with risk of AQP4-Ab positive NMO in Southern Han Chinese.

Disease onset in familial and sporadic primary progressive multiple sclerosis

The pathophysiology of primary progressive (PP) multiple sclerosis (MS) involves diffuse axonal degeneration which is believed to start early in the disease process, even before the onset of clinical symptoms. Symptomatic onset then occurs when this process reaches a threshold after which the axonal loss can no longer be compensated. A preliminary study showed that patients with familial PPMS had an earlier clinical onset than patients with sporadic disease, suggesting a hereditary component to the disease process of PPMS. In this study, we combined data from two large, population-based, longitudinal MS databases to investigate disease onset in familial and sporadic PPMS. We examined 411 patients with PPMS. There were no differences in gender distribution or onset symptoms between familial and sporadic PPMS. Patients with familial PPMS were significantly younger at disease onset (n = 84, median age: 37.6 years) than patients with sporadic disease (n = 327, median age: 42.7, p = 0.007). This difference was due to a greater proportion of familial cases with a disease onset before the age of 30 and a smaller proportion with disease onset between 40 and 50 years of age (p = 0.002). Gender had no significant effect on the age at disease onset. Further analyses showed that these findings were unlikely to be due to ascertainment bias towards an earlier diagnosis in familial cases. Our findings suggest a hereditary component to the disease process of PPMS. It would be worthwhile to identify patients with familial PPMS for future research on disease modifying genes in MS.

Allelic variation in the Tyk2 and EGF genes as potential genetic determinants of CNS repair

The potential for endogenous remyelination and axonal protection can be an important factor in determining disease outcome in demyelinating diseases like multiple sclerosis. In many multiple sclerosis (MS) patients CNS repair fails or is incomplete whereas in others the disease is accompanied by extensive repair of demyelinated lesions. We have described significant differences in the ability of two strains of mice to repair CNS damage following Theiler's virus-induced demyelination: FVB/NJ (FVB) mice repair damaged myelin spontaneously and completely, whereas B10.D1-H2(q)/SgJ (B10.Q) mice are deficient in the repair process. A QTL analysis was performed to identify genetic loci that differentially regulate CNS repair following chronic demyelination in these strains and two QTL were detected: one on chromosome 3 with a LOD score of 9.3 and a second on chromosome 9 with a LOD score of 14.0. The mouse genes for epidermal growth factor (EGF) and Tyk2 are encoded within the QTL on chromosomes 3 and 9, respectively. Sequence polymorphisms between the FVB and B10.Q strains at both the EGF and Tyk2 loci define functional variations consistent with roles for these genes in regulating myelin repair. EGF is a key regulator of cell growth and development and we show a sevenfold increase in EGF expression in FVB compared to B10.Q mice. Tyk2 is a Janus kinase that plays a central role in controlling the T(H)1 immune response and we show that attenuation of Tyk2 function correlates with enhanced CNS repair.

Paraoxonase 1 polymorphisms are not related with the risk for multiple sclerosis

It has been suggested a possible role of oxidative stress and lipid peroxidation in the inflammatory processes and in the pathogenesis of multiple sclerosis. Human serum paraoxonase 1 is a polymorphic enzyme encoded by the gene PON1, located in chromosome 7q21.3, that plays a major role in the metabolism of organophosporus compounds, and in the protection against oxidative stress. Paraoxonase-1 activity has been found decreased in the plasma of multiple sclerosis patients. An association between PON1 polymorphism and the risk of multiple sclerosis has been described in Italians. To investigate the possible association between the PON1 genotype and allelic variants of the polymorphisms L55M and Q192R and the risk for multiple sclerosis in the Spanish Caucasian population; we studied the frequency of the PON1 genotypes and allelic variants in 228 patients with multiple sclerosis and 220 healthy controls using a PCR-RLFP method. The frequencies of the PON1 genotypes and allelic variants did not differ significantly between patients and controls, and were unrelated with gender, age of onset, and course of the disease. The OR (95% confidence intervals) for the variant alleles PON1-55L and PON1-192R were 0.96 (0.73-1.26) and 1.01 (0.76-1.35), respectively. The results of the present study suggest that PON1 polymorphism is not related with the risk for multiple sclerosis in our population.

Multiple sclerosis and the major histocompatibility complex

PURPOSE OF REVIEW

Multiple sclerosis (MS) is the most common neurological disease affecting young adults. The cause is unknown, but detailed epidemiological and genetic studies have shown a clear inherited component. We review here some of the recent findings of MS genetics with a particular focus on genes of the major histocompatibility complex (MHC).

RECENT FINDINGS

Recent studies add further complexity to the role of the MHC in MS. Reported MHC associations are complex, involving haplotypes rather than single alleles and may involve epigenetic mechanisms and other modulators of gene expression. MHC class II haplotypes display a hierarchy of risks, including protective effects and epistatic interactions, which together dwarf any non-MHC genetic effect. Genes in the MHC region have been shown to influence disease severity, display parent-of-origin effects and interact with a major environmental candidate for MS, vitamin D.

SUMMARY

The MHC class II association with MS is not as straightforward as previously thought. A complete understanding of the epistatic interactions and epigenetic features of this region will be important to understand disease pathogenesis and likely aid the discovery of new therapeutics.

Multiple sclerosis association study with the TENR-IL2-IL21 region in a Spanish population

Polymorphisms from the TENR-IL2-IL21 block in the 4q27 chromosome were recently associated with type 1 diabetes, celiac disease, rheumatoid arthritis and psoriasis. We undertook this study to investigate the potential role of polymorphisms rs3136534, rs6822844 and rs2069762 (-330 T/G IL2) in multiple sclerosis (MS) (805 patients of Spanish Caucasian origin and 952 health controls). We did not find evidence for association with any single nucleotide polymorphisms (SNPs) tested. Allele and genotype frequencies of the SNPs, which were studied, were similar in DRB1*15-positive or DRB1*15-negative patients. After stratification of MS patients by clinical course, a weak association was observed with rs2069762 G allele and haplotype bearing this allele with secondary progressive MS, although these cases represent 22% of the MS cases. Our results did not show major influence of TENR-IL2-IL21 locus on susceptibility or disease progression in MS. However, we could not exclude completely the effect in MS for this region. Additional studies, using much larger sample sizes and analysis of additional polymorphisms in the gene and its flanking region, will be required to ascertain their contributions to MS susceptibility.

The genetics and epigenetics of autoimmune diseases

Self tolerance loss is fundamental to autoimmunity. While understanding of immune regulation is expanding rapidly, the mechanisms causing loss of tolerance in most autoimmune diseases remain elusive. Autoimmunity is believed to develop when genetically predisposed individuals encounter environmental agents that trigger the disease. Recent advances in the genetic and environmental contributions to autoimmunity suggest that interactions between genetic elements and epigenetic changes caused by environmental agents may be responsible for inducing autoimmune disease. Genetic loci predisposing to autoimmunity are being identified through multi-center consortiums, and the number of validated genes is growing rapidly. Recent reports also indicate that the environment can contribute to autoimmunity by modifying gene expression through epigenetic mechanisms. This article will review current understanding of the genetics and epigenetics of lupus, rheumatoid arthritis, multiple sclerosis and type 1 diabetes, using systemic lupus erythematosus as the primary example. Other autoimmune diseases may have a similar foundation.