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An extremes of outcome strategy provides evidence that multiple sclerosis severity is determined by alleles at the HLA-DRB1 locus.

ABSTRACT: Multiple sclerosis (MS) is a common inflammatory disease of the central nervous system unsurpassed for variability in disease outcome. A cohort of sporadic MS cases (n = 163), taken from opposite extremes of the distribution of long-term outcome, was used to determine the role of the HLA-DRB1 locus on MS disease severity. Genotyping sets of benign and malignant MS patients showed that HLA-DRB1*01 was significantly underrepresented in malignant compared with benign cases. This allele appears to attenuate the progressive disability that characterizes MS in the long term. The observation was doubly replicated in (i) Sardinian benign and malignant patients and (ii) a cohort of affected sibling pairs discordant for HLA-DRB1*01. Among the latter, mean disability progression indices were significantly lower in those carrying the HLA-DRB1*01 allele compared with their disease-concordant siblings who did not. The findings were additionally supported by similar transmission distortion of HLA-DRB1*04 subtypes closely related to HLA-DRB1*01. The protective effect of HLA-DRB1*01 in sibling pairs may result from a specific epistatic interaction with the susceptibility allele HLA-DRB1*1501. A high-density (>700) SNP examination of the MHC region in the benign and malignant patients could not identify variants differing significantly between the two groups, suggesting that HLA-DRB1 may itself be the disease-modifying locus. We conclude that HLA-DRB1*01, previously implicated in disease resistance, acts as an independent modifier of disease progression. These results closely link susceptibility to long-term outcome in MS, suggesting that shared quantitative MHC-based mechanisms are common to both, emphasizing the central role of this region in pathogenesis.

SUBMITTER: DeLuca GC

PROVIDER: S-EPMC2409238 | biostudies-literature | 2007 Dec

REPOSITORIES: biostudies-literature

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An extremes of outcome strategy provides evidence that multiple sclerosis severity is determined by alleles at the HLA-DRB1 locus.

DeLuca G C GC Ramagopalan S V SV Herrera B M BM Dyment D A DA Lincoln M R MR Montpetit A A Pugliatti M M Barnardo M C N MC Risch N J NJ Sadovnick A D AD Chao M M Sotgiu S S Hudson T J TJ Ebers G C GC

Proceedings of the National Academy of Sciences of the United States of America 20071217 52

Multiple sclerosis (MS) is a common inflammatory disease of the central nervous system unsurpassed for variability in disease outcome. A cohort of sporadic MS cases (n = 163), taken from opposite extremes of the distribution of long-term outcome, was used to determine the role of the HLA-DRB1 locus on MS disease severity. Genotyping sets of benign and malignant MS patients showed that HLA-DRB1*01 was significantly underrepresented in malignant compared with benign cases. This allele appears to a ...[more]

PMID: 18087043

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Project description:In Northern European descended populations, genetic susceptibility for multiple sclerosis (MS) is associated with alleles of the human leukocyte antigen (HLA) Class II gene DRB1. Whether other major histocompatibility complex (MHC) genes contribute to MS susceptibility is controversial.A case control analysis was performed using 958 single nucleotide polymorphisms (SNPs) spanning the MHC assayed in two independent datasets. The discovery dataset consisted of 1,018 cases and 1,795 controls and the replication dataset was composed of 1,343 cases and 1,379 controls. The most significantly MS-associated SNP in the discovery dataset was rs3135391, a Class II SNP known to tag the HLA-DRB1*15:01 allele, the primary MS susceptibility allele in the MHC (O.R. = 3.04, p < 1 x 10(-78)). To control for the effects of the HLA-DRB1*15:01 haplotype, case control analysis was performed adjusting for this HLA-DRB1*15:01 tagging SNP. After correction for multiple comparisons (false discovery rate = .05) 52 SNPs in the Class I, II and III regions were significantly associated with MS susceptibility in both datasets using the Cochran Armitage trend test. The discovery and replication datasets were merged and subjects carrying the HLA-DRB1*15:01 tagging SNP were excluded. Association tests showed that 48 of the 52 replicated SNPs retained significant associations with MS susceptibility independently of the HLA-DRB1*15:01 as defined by the tagging SNP. 20 Class I SNPs were associated with MS susceptibility with p-values < or = 1 x 10(-8). The most significantly associated SNP was rs4959039, a SNP in the downstream un-translated region of the non-classical HLA-G gene (Odds ratio 1.59, 95% CI 1.40, 1.81, p = 8.45 x 10(-13)) and is in linkage disequilibrium with several nearby SNPs. Logistic regression modeling showed that this SNP's contribution to MS susceptibility was independent of the Class II and Class III SNPs identified in this screen.A MHC Class I locus contributes to MS susceptibility independently of the HLA-DRB1*15:01 haplotype.

Project description:Multiple sclerosis (MS), a common central nervous system inflammatory disease, has a major heritable component. Susceptibility is associated with the MHC class II region, especially HLA-DRB5*0101-HLA-DRB1*1501-HLA-DQA1*0102-HLA-DQB1*0602 haplotypes(hereafter DR2), which dominate genetic contribution to MS risk. Marked linkage disequilibrium (LD) among these loci makes identification of a specific locus difficult. The once-leading candidate, HLA-DRB1*15, localizes to risk, neutral, and protective haplotypes. HLA-DRB1*15 and HLA-DQB1*0602, nearly always located together on a small ancestral chromosome segment, are strongly MS-associated. One intervening allele on this haplotype, viz. HLA-DQA1*0102, shows no primary MS association. Two Canadian cohorts (n = 830 and n = 438 trios) genotyped for HLA-DRB1, HLA-DQA1 and HLA-DQB1 alleles were tested for association using TDT. To evaluate epistasis involving HLA-DRB1*15, transmissions from HLA-DRB1*15-negative parents were stratified by the presence/absence of HLA-DRB1*15 in affected offspring. All 3 alleles contribute to MS susceptibility through novel epistatic interactions. HLA-DQA1*0102 increased disease risk when combined with HLA-DRB1*1501 in trans, thereby unambiguously implicating HLA-DQ in MS susceptibility. Three-locus haplotypes demonstrated that HLA-DRB1*1501 and HLA-DQB1*0602 each influence risk. Transmissions of rare morcellated DR2 haplotypes showed no interaction with HLA-DQA1*0102. Incomplete haplotypes bearing only HLA-DRB1*1501 or HLA-DQB1*0602 did not predispose to MS. Balanced reciprocal transmission distortion can mask epistatic allelic association. These findings implicate epistasis among HLA class II alleles in human immune responses generally, provide partial explanation for intense linkage disequilibrium in the MHC, have relevance to animal models, and demonstrate key roles for DR2-specific interactions in MS susceptibility. MHC disease associations may be more generally haplotypic or diplotypic.

Project description:Risk of the development of multiple sclerosis (MS) is known to be increased in individuals bearing distinct class II human leukocyte antigen (HLA) variants, whereas some of them may have a protective effect. Here we analyzed distribution of a highly polymorphous HLA-DRB1 locus in more than one thousand relapsing-remitting MS patients and healthy individuals of Russian ethnicity. Carriage of HLA-DRB1*15 and HLA-DRB1*03 alleles was associated with MS risk, whereas carriage of HLA-DRB1*01 and HLA-DRB1*11 was found to be protective. Analysis of genotypes revealed the compensatory effect of risk and resistance alleles in trans. We have identified previously unknown MBP153-161 peptide located at the C-terminus of MBP protein and MBP90-98 peptide that bound to recombinant HLA-DRB1*01:01 protein with affinity comparable to that of classical antigenic peptide 306-318 from the hemagglutinin (HA) of the influenza virus demonstrating the ability of HLA-DRB1*01:01 to present newly identified MBP153-161 and MBP90-98 peptides. Measurements of kinetic parameters of MBP and HA peptides binding to HLA-DRB1*01:01 catalyzed by HLA-DM revealed a significantly lower rate of CLIP exchange for MBP153-161 and MBP90-98 peptides as opposed to HA peptide. Analysis of the binding of chimeric MBP-HA peptides demonstrated that the observed difference between MBP153-161, MBP90-98, and HA peptide epitopes is caused by the lack of anchor residues in the C-terminal part of the MBP peptides resulting in a moderate occupation of P6/7 and P9 pockets of HLA-DRB1*01:01 by MBP153-161 and MBP90-98 peptides in contrast to HA308-316 peptide. This leads to the P1 and P4 docking failure and rapid peptide dissociation and release of empty HLA-DM-HLA-DR complex. We would like to propose that protective properties of the HLA-DRB1*01 allele could be directly linked to the ability of HLA-DRB1*01:01 to kinetically discriminate between antigenic exogenous peptides and endogenous MBP derived peptides.

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An extremes of outcome strategy provides evidence that multiple sclerosis severity is determined by alleles at the HLA-DRB1 locus.

Publications

An extremes of outcome strategy provides evidence that multiple sclerosis severity is determined by alleles at the HLA-DRB1 locus.

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