Laura Leyva

Interferon regulatory factor 5 (IRF5) gene variants are associated with multiple sclerosis in three distinct populations

Background: IRF5 is a transcription factor involved both in the type I interferon and the toll-like receptor signalling pathways. Previously, IRF5 has been found to be associated with systemic lupus erythematosus, rheumatoid arthritis and inflammatory bowel diseases. Here we investigated whether polymorphisms in the IRF5 gene would be associated with yet another disease with features of autoimmunity, multiple sclerosis (MS). Methods: We genotyped nine single nucleotide polymorphisms and one insertion-deletion polymorphism in the IRF5 gene in a collection of 2337 patients with MS and 2813 controls from three populations: two case–control cohorts from Spain and Sweden, and a set of MS trio families from Finland. Results: Two single nucleotide polymorphism (SNPs) (rs4728142, rs3807306), and a 5 bp insertion-deletion polymorphism located in the promoter and first intron of the IRF5 gene, showed association signals with values of p<0.001 when the data from all cohorts were combined. The predisposing alleles were present on the same common haplotype in all populations. Using electrophoretic mobility shift assays we observed allele specific differences in protein binding for the SNP rs4728142 and the 5 bp indel, and by a proximity ligation assay we demonstrated increased binding of the transcription factor SP1 to the risk allele of the 5 bp indel. Conclusion: These findings add IRF5 to the short list of genes shown to be associated with MS in more than one population. Our study adds to the evidence that there might be genes or pathways that are common in multiple autoimmune diseases, and that the type I interferon system is likely to be involved in the development of these diseases.

Effects of the multiple sclerosis associated −330 promoter polymorphism in IL2 allelic expression

The -330 IL2 gene promoter polymorphism has been associated with multiple sclerosis (MS) [J. Neuroimmunol. 119 (2001) 101], but the basis underlying this association remains unknown to date. In the present work, we have found that IL2 promoter-luciferase constructs, transfected in Jurkat cell line, showed twofold higher levels of gene expression in the -330 G allele. However, the transcriptional effect of this polymorphism in lymphocytes showed that the G allele was related to lower expression of IL2. This difference increased in the patient group. Divergence between in vivo and in vitro influence of the -330 IL2 promoter polymorphic site suggests the existence of additional unknown polymorphisms affecting gene regulation. Our data show an increased IL2 expression among GT and TT genotypes previously associated with susceptibility to MS.

IFNAR1 and IFNAR2 polymorphisms confer susceptibility to multiple sclerosis but not to interferon-beta treatment response.

We investigated the role of three polymorphisms in the IFNAR1 (SNPs 18417 and -408) and IFNAR2 (SNP 11876) genes in multiple sclerosis (MS) susceptibility and in the IFNbeta treatment response in a group of 147 patients and 210 controls undergoing interferon therapy during the last 2 years. Only the 18417 and the 11876 SNPs showed an association with disease susceptibility (p=0.001 and 0.035, respectively) although no differential genotype distribution were observed between interferon responders and non-responder MS patients. No alteration of the expression level of IFNAR-1 was observed with respect to the -408 genotypes or to interferon treatment response. These data suggest a role for the IFNAR pathway in susceptibility to MS.

IL2RA/CD25 Gene Polymorphisms: Uneven Association with Multiple Sclerosis (MS) and Type 1 Diabetes (T1D)

Background IL-2 receptor (IL2R) alpha is the specific component of the high affinity IL2R system involved in the immune response and in the control of autoimmunity. Methods and Results Here we perform a replication and fine mapping of the IL2RA gene region analyzing 3 SNPs previously associated with multiple sclerosis (MS) and 5 SNPs associated with type 1 diabetes (T1D) in a collection of 798 MS patients and 927 matched Caucasian controls from the south of Spain. We observed association with MS in 6 of 8 SNPs. The rs1570538, at the 3′- UTR extreme of the gene, previously reported to have a weak association with MS, is replicated here (P = 0.032). The most associated T1D SNP (rs41295061) was not associated with MS in the present study. However, the rs35285258, belonging to another independent group of SNPs associated with T1D, showed the maximal association in this study but different risk allele. We replicated the association of only one (rs2104286) of the two IL2RA SNPs identified in the recently performed genome-wide association study of MS. Conclusions These findings confirm and extend the association of this gene with MS and reveal a genetic heterogeneity of the associated polymorphisms and risk alleles between MS and T1D suggesting different immunopathological roles of IL2RA in these two diseases.

The autoimmune disease-associated KIF5A, CD226 and SH2B3 gene variants confer susceptibility for multiple sclerosis.

Genome-wide association studies (GWAS) have revealed that different diseases share susceptibility variants. Twelve single-nucleotide polymorphisms (SNPs) previously associated with different immune-mediated diseases in GWAS were genotyped in a Caucasian Spanish population of 2864 multiple sclerosis (MS) patients and 2930 controls. Three SNPs were found to be associated with MS: rs1678542 in KIF5A (P=0.001, odds ratio (OR)=1.13, 95% confidence interval (CI)=1.05–1.23); rs3184504 in SH2B3 (P=0.00001, OR=1.19, 95% CI=1.10–1.27) and rs763361 in CD226 (P=0.00007, OR=1.16, 95%CI=1.08–1.25). These variants have previously been associated with rheumatoid arthritis and type 1 diabetes. The SH2B3 polymorphism has additionally been associated with systemic lupus erythematosus. Our results, in addition to validating some of these loci as risk factors for MS, are consistent with shared genetic mechanisms underlying different immune-mediated diseases. These data may help to shape the contribution of each pathway to different disorders.

DQB1*0602 allele shows a strong association with multiple sclerosis in patients in Malaga, Spain

Abstract.Background:The human leukocyte antigen (HLA) class II DR2 haplotype (DRB1*1501, DQA1*0102, DQB1*0602) has been associated with multiple sclerosis (MS) in all ethnic groups and very strongly in Caucasians.Aim:To investigate the possible HLA class II (DRB1, DQA1 and DQB1) associations with MS in Malaga, southern Spain.Methods:We analysed the HLA class II sub-regions DRB1, DQA1 and DQB1 by polymerase chain reaction (PCR) and sequence-specific oligonucleotide probe hybridization (PCR/SSO) for DRB1 and DQB1 and with sequence-specific primers (PCR/SSP) for DRB1 subtypes and DQA1. Possible HLA class II associations with clinical MS characteristics were investigated in 149 subjects with and 160 without MS.Results:Associations were detected between MS and the HLA class II alleles DRB1*1501 (45.6 % vs. 21.3%, p = 0.001), DQA1*0102 (44% vs. 29.4%, p = 0.001) and DQB1*0602 (45% vs. 20.6%, p = 0.001). The DR2 haplotype (DRB1*1501, DQA1*0102, DQB1*0602) was associated with MS (43.6 % vs. 20%, p = 0.002). DQB1*0602 was the only allele that maintained an association with MS in a logistic regression model. No HLA class II alleles or genotypes were significantly associated with any clinical characteristics of MS.Conclusions:Our results confirm the positive association of the DR2 haplotype with MS, particularly the allele DQB1*0602, in the population studied. DR4 was not associated with the disease in Malaga. HLA class II alleles or haplotypes were not associated with clinical or demographic characteristics, or clinical form or severity of MS.

Protein tyrosine phosphatase gene (PTPN22) polymorphism in multiple sclerosis.

Sirs: Multiple sclerosis (MS) is a common inflammatory disease of the central nervous system (CNS) with a complex pathogenesis involving multiple genetic and environmental contributions. Alterations in the signalling pathway that regulate T-cell tyrosine phosphorylation play an important role in MS [6]. Tyrosine phosphorylation is regulated by the equal and balanced action of protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs) [1]. The lymphoid-specific phosphatase (LYP), encoded by the PTPN22 gene, is important in negative control of T-cell activation and in T-cell development. A functional polymorphism at nucleotide 1858 in codon 620 (Arg620Trp) in the PTPN22 gene has been associated with type 1 diabetes mellitus (T1D), rheumatoid arthritis (RA), and systemic lupus erythematosus (SLE) in humans [3, 4, 7, 8]. In the present study, we tested the possible role of the 1858C→T variant of the PTPN22 gene in MS predisposition. We examined the distribution frequency of the PTPN22 1858C→T polymorphism of 120 patients with clinically defined MS and 200 healthy controls by a TaqMan 5’ allelic discrimination [8]. The frequencies of 1858C/C, 1858C/T and 1858T/T genotypes were 87.5 %%, 12 % and 0.5 % respectively in controls and 83.3 %, 15.8 % and 0.9 % in the patient group. The allele and genotype distribution frequencies were similar in MS patients and controls and were in Hardy-Weinberg equilibrium. Indeed, stratification of MS patients according to their clinical phenotypes (RR and SP) and genus revealed no significant differences (data not shown). This lack of association of the PTPN22 1858C→T polymorphism with MS should be interpreted cautiously. Because of the relatively small sample size, slight effects may be not uncovered and therefore these results do not completely rule out the possibility of an association with MS. The association of RA, T1D and SLE susceptibility with the PTPN22 1858C→T polymorphism suggests that the PTPN22 1858T allele predisposes individuals to developing autoimmune diseases. However, the PTPN22 1858C→T polymorphism seems not to be a critical point in the susceptibility to MS. Given the expression of this molecule in many immunological relevant cell types, our data support the hypothesis that PTPN22 may act in different ways in different autoimmune diseases. It is possible that different genetic backgrounds could condition the effect of the PTPN22 polymorphism, but this seems not to be the reason since the PTPN22 polymorphism confers susceptibility to other autoimmune diseases such as RA and SLE with the same genetic background [8]. Furthermore, there are no significant differences between 1858C→T genotype distribution of control groups from North America, where an association of the PTPN22 1858C→T polymorphism with RA and SLE has been described [3, 7], and South Spain populations. It is worth mentioning that the Sardinia population has a high MS prevalence (150/100,000) [10]). However, they have the lowest proportion of 1858 T allele which is associated with susceptibility to autoimmune diseases [4]. This is in concordance with the absence of PTPN22 1858 T polymorphism association with MS. Similar contradictory findings have been reported concerning the influence of CTLA-4 gene in autoimmunity. While the CTLA-4CT60 marker has been associated with a range of autoimmune diseases, such as T1D, Graves’ disease, thyroiditis and SLE [5, 11], no linkage was observed with RA [9, 2] These findings support the notion that common susceptibility alleles are not shared among all autoimmune diseases, but rather among groups of these conditions. In conclusion, our data suggest that the PTPN22 1858 SNP has no, or only a negligible effect on MS susceptibility in the Spanish population. However, a minor effect of the PTPN22 SNP cannot be ruled out, and this may only be verifiable in an extremely large data set.

Lipid‐specific immunoglobulin M bands in cerebrospinal fluid are associated with a reduced risk of developing progressive multifocal leukoencephalopathy during treatment with natalizumab

Progressive multifocal leukoencephalopathy (PML) is a serious side effect associated with natalizumab treatment in multiple sclerosis (MS). PML risk increases in individuals seropositive for anti–John Cunningham virus (JC) antibodies, with prolonged duration of natalizumab treatment, and with prior exposure to immunosuppressants. We explored whether the presence of lipid‐specific immunoglobulin M oligoclonal bands in cerebrospinal fluid (CSF; IgM bands), a recognized marker of highly inflammatory MS, may identify individuals better able to counteract the potential immunosuppressive effect of natalizumab and hence be associated with a reduced risk of developing PML.

Genome-wide association study of multiple sclerosis confirms a novel locus at 5p13.1.

Multiple Sclerosis (MS) is the most common progressive and disabling neurological condition affecting young adults in the world today. From a genetic point of view, MS is a complex disorder resulting from the combination of genetic and non-genetic factors. We aimed to identify previously unidentified loci conducting a new GWAS of Multiple Sclerosis (MS) in a sample of 296 MS cases and 801 controls from the Spanish population. Meta-analysis of our data in combination with previous GWAS was done. A total of 17 GWAS-significant SNPs, corresponding to three different loci were identified:HLA, IL2RA, and 5p13.1. All three have been previously reported as GWAS-significant. We confirmed our observation in 5p13.1 for rs9292777 using two additional independent Spanish samples to make a total of 4912 MS cases and 7498 controls (ORpooled = 0.84; 95%CI: 0.80–0.89; p = 1.36×10-9). This SNP differs from the one reported within this locus in a recent GWAS. Although it is unclear whether both signals are tapping the same genetic association, it seems clear that this locus plays an important role in the pathogenesis of MS.

Study of binding and neutralising antibodies to interferon-β in two groups of relapsing-remitting multiple sclerosis patients

Abstract Interferon (IFN)-β is generally considered an effective treatment for multiple sclerosis (MS); however, some patients do not respond to this therapy, possibly due to the production of neutralising antibodies (NAB) which can prevent the biological effect of IFN-β. We compared the two types of IFN-β, the glycosylated IFN-β1a and the non-glycosylated IFN-β1b, as their chemical differences may entail differing immunogenic capacities. We studied 22 relapsing-remitting MS patients treated with IFN-β1a and 31 treated with IFN-β1b for 1 year, using the same assay and criteria, to compare the two types of IFN-β in their ability to induce binding and neutralising antibodies and examined the correlation of the findings with the clinical data. Binding antibodies to IFN-β1a and IFN-β1b were determined by enzyme-linked immunosorbent assay. A bioassay was used to detect and quantify the NABs to IFN-β, measuring the capacity of NABs to block the antiviral resistance induced by IFNs. Binding antibodies were found in 32 % of those treated with IFN-β1a and in 52 % of those treated with IFN-β1b; NABs were found in 14 % and 24 %, respectively. Both groups showed a significant decrease in relapse rate during the first year of treatment. These results demonstrate that the IFN-β1b molecule is more immunogenic than the IFN-β1a molecule. This may be due to the non-glycosylated, chemical structure of the former, which can produce aggregates and enhance antibody production. No association was found between the presence of NABs and the clinical status of the patients.