Boel Brynedal

HLA-A Confers an HLA-DRB1 Independent Influence on the Risk of Multiple Sclerosis

A recent high-density linkage screen confirmed that the HLA complex contains the strongest genetic factor for the risk of multiple sclerosis (MS). In parallel, a linkage disequilibrium analysis using 650 single nucleotide polymorphisms (SNP) markers of the HLA complex mapped the entire genetic effect to the HLA-DR-DQ subregion, reflected by the well-established risk haplotype HLA-DRB1*15,DQB1*06. Contrary to this, in a cohort of 1,084 MS patients and 1,347 controls, we show that the HLA-A gene confers an HLA-DRB1 independent influence on the risk of MS (P = 8.4×10−10). This supports the opposing view, that genes in the HLA class I region indeed exert an additional influence on the risk of MS, and confirms that the class I allele HLA-A*02 is negatively associated with the risk of MS (OR = 0.63, P = 7×10−12) not explained by linkage disequilibrium with class II. The combination of HLA-A and HLA-DRB1 alleles, as represented by HLA-A*02 and HLA-DRB1*15, was found to influence the risk of MS 23-fold. These findings imply complex autoimmune mechanisms involving both the regulatory and the effector arms of the immune system in the triggering of MS.

The impact of HLA-A and -DRB1 on age at onset, disease course and severity in Scandinavian multiple sclerosis patients

The human leucocyte antigen (HLA) class II haplotype DRB1*15–DQB1*06 (DR15–DQ6) is associated with susceptibility to multiple sclerosis (MS), and HLA class I associations in MS have also been reported. However, the influence of HLA class I and II alleles on clinical phenotypes in MS has not yet been completely studied. This study aimed at evaluating the impact of HLA‐A and ‐DRB1 alleles on clinical variables in Scandinavian MS patients. The correlation between HLA‐A or ‐DRB1 alleles and age at onset, disease course and Multiple Sclerosis Severity Score (MSSS) were studied in 1457 Norwegian and Swedish MS patients by regression analyses and Kruskal–Wallis rank sum test. Presence of HLA‐DRB1*15 was correlated with younger age at onset of disease (corrected P = 0.009). No correlation was found between HLA‐A and the variables studied. This study analysed the effect of HLA‐A on clinical variables in a large Scandinavian sample set, but could not identify any significant contribution from HLA‐A on the clinical phenotype in MS. However, associations between HLA‐DRB1*15 and age at onset of MS were reproduced in this extended Scandinavian MS cohort.

Different HLA-DRB1 allele distributions in distinct clinical subgroups of sarcoidosis patients

BackgroundA strong genetic influence by the MHC class II region has been reported in sarcoidosis, however in many studies with different results. This may possibly be caused by actual differences between distinct ethnic groups, too small sample sizes, or because of lack of accurate clinical subgrouping.Subjects and methodsIn this study we HLA typed a large patient population (n = 754) recruited from one single centre. Patients were sub-grouped into those with Löfgrens syndrome (LS) (n = 302) and those without (non-Löfgrens) (n = 452), and the majority of them were clinically classified into those with recovery within two years (resolving) and those with signs of disease for more than two years (non-resolving). PCR was used for determination of HLA-DRB1 alleles. Swedish healthy blood donors (n = 1366) served as controls.ResultsThere was a dramatic difference in the distribution of HLA alleles in LS compared to non-LS patients (p = 4 × 10-36). Most notably, DRB1*01, DRB1*03 and DRB1*14, clearly differed in LS and non-LS patients. In relation to disease course, DRB1*07, DRB1*14 and DRB1*15 generally associated with, while DRB1*01 and DRB1*03 protected against, a non-resolving disease. Interestingly, the clinical influence of DRB1*03 (good prognosis) dominated over that of DRB1*15 (bad prognosis).ConclusionsWe found several significant differences between LS and non-LS patients and we therefore suggest that genetic association studies in sarcoidosis should include a careful clinical characterisation and sub-grouping of patients, in order to reveal true genetic associations. This may be particularly accurate to do in the heterogeneous non-LS group of patients.

MGAT5 alters the severity of multiple sclerosis

Multiple Sclerosis (MS) is a genetically complex immune mediated, demyelinating disease of the central nervous system. To date no genetic variants have been unambiguously linked to disease severity. We have conducted a genome wide screen, using Affymetrix Genechip 500K technology, for severity in 1040 MS patients. Two markers within MGAT5, a gene coding for a glycosylation enzyme, were found to be significantly associated with outcome in the screening as well as in an independent population (combined p-values: 2.8 x 10(-6) and 1.5 x 10(-7)).

Gene expression profiling in multiple sclerosis: a disease of the central nervous system, but with relapses triggered in the periphery?

The aetiology of multiple sclerosis (MS), an autoimmune demyelinating disease of the central nervous system (CNS), includes both genetic and environmental factors, but the pathogenesis is still incompletely known. We performed gene expression profiling on paired cerebrospinal fluid (CSF) and peripheral blood mononuclear cells (PBMCs) samples from 26 MS patients without immunomodulatory treatment, sampled in relapse or remission, and 18 controls using Human Genome U133 plus 2.0 arrays (Affymetrix). In the CSF, 939 probe sets detected differential expression in MS patients compared to controls, but none in PBMCs, confirming that CSF cells might mirror the disease processes. The regulation of selected transcripts in CSF of MS patients was confirmed by quantitative PCR. Unexpectedly however, when comparing MS patients in relapse to those in remission, 266 probe sets detected differential expression in PBMCs, but not in CSF cells, indicating the importance of events outside of the CNS in the triggering of relapse.

Importance of Human Leukocyte Antigen (HLA) Class I and II Alleles on the Risk of Multiple Sclerosis

Multiple sclerosis (MS) is a complex disease of the central nervous system of unknown etiology. The human leukocyte antigen (HLA) locus on chromosome 6 confers a considerable part of the susceptibility to MS, and the most important factor is the class II allele HLA-DRB1*15:01. In addition, we and others have previously established a protective effect of HLA-A*02. Here, we genotyped 1,784 patients and 1,660 healthy controls from Scandinavia for the HLA-A, HLA-B, HLA-C and HLA-DRB1 genes and investigated their effects on MS risk by logistic regression. Several allele groups were found to exert effects independently of DRB1*15 and A*02, in particular DRB1*01 (OR = 0.82, p = 0.034) and B*12 (including B*44/45, OR = 0.76, p = 0.0028), confirming previous reports. Furthermore, we observed interaction between allele groups: DRB1*15 and DRB1*01 (multiplicative: OR = 0.54, p = 0.0041; additive: AP = 0.47, p = 4×10−06), DRB1*15 and C*12 (multiplicative: OR = 0.37, p = 0.00035; additive: AP = 0.58, p = 2.6×10−05), indicating that the effect size of these allele groups varies when taking DRB1*15 into account. Analysis of inferred haplotypes showed that almost all DRB1*15 bearing haplotypes were risk haplotypes, and that all A*02 bearing haplotypes were protective as long as they did not carry DRB1*15. In contrast, we found one class I haplotype, carrying A*02-C*05-B*12, which abolished the risk of DRB1*15. In conclusion, these results confirms a complex role of HLA class I and II genes that goes beyond DRB1*15 and A*02, in particular by including all three classical HLA class I genes as well as functional interactions between DRB1*15 and several alleles of DRB1 and class I genes.

A common haplotype of the C‐C chemokine receptor 2 gene and HLA‐DRB1*0301 are independent genetic risk factors for Löfgren’s syndrome

Aim.  Sarcoidosis is a heterogeneous disorder with a strong genetic influence. Genetic factors are also thought to influence disease severity and outcome. We sought to determine whether polymorphisms within CCR2 gene predispose to Löfgren’s syndrome – a clinically and genetically distinct sarcoidosis phenotype – and, importantly, whether this association is independent of the known association with the HLA‐DRB1*0301 allele.

Two HLA class I genes independently associated with multiple sclerosis

OBJECTIVE The risk of multiple sclerosis (MS) is influenced by HLA-DRB1, while protective effects have been proposed for HLA-A*02 and HLA-C*05. Our aim was to further understand the role of HLA class I in MS through a comprehensive investigation. METHODS 1529 MS patients and 1814 controls from Sweden and Norway were genotyped for HLA-DRB1, HLA-A, and HLA-C. Simultaneous analysis of all alleles while adjusting for confounding was achieved using logistic regression. RESULTS We observed independent effects of all three genes. We confirm the HLA-A*02 (OR=0.73, p=9.2 x 10(-4)) association and report a novel effect of HLA-C*08 (OR=1.85, p=0.0093). CONCLUSIONS The HLA class I region contains two factors modulating MS risk, characterized by independent associations with HLA-A and HLA-C.

Human Leukocyte Antigen Genes and Interferon Beta Preparations Influence Risk of Developing Neutralizing Anti-Drug Antibodies in Multiple Sclerosis

A significant proportion of patients with multiple sclerosis who receive interferon beta (IFNβ) therapy develop neutralizing antibodies (NAbs) that reduce drug efficacy. To investigate if HLA class I and II alleles are associated with development of NAbs against IFNβ we analyzed whether NAb status and development of NAb titers high enough to be biologically relevant (>150 tenfold reduction units/ml) correlated with the HLA allele group carriage in a cohort of 903 Swedish patients with multiple sclerosis treated with either intramuscular IFNβ-1a, subcutaneous IFNβ-1a or subcutaneous IFNβ-1b. Carriage of HLA-DRB1*15 was associated with increased risk of developing NAbs and high NAb titers. After stratification based on type of IFNβ preparation, HLA-DRB1*15 carriage was observed to increase the risk of developing NAbs as well as high NAb titers against both subcutaneous and intramuscular IFNβ-1a. Furthermore, in patients receiving subcutaneous IFNβ-1a carriage of HLA-DQA1*05 decreased the risk for high NAb titers. In IFNβ-1b treated patients, HLA-DRB1*04 increased the risk of developing high NAb titers, and in a subgroup analysis of DRB1*04 alleles the risk for NAbs was increased in DRB1*04:01 carriers. In conclusion, there is a preparation-specific genetically determined risk to develop NAbs against IFNβ high enough to be clinically relevant in treatment decisions for patients with multiple sclerosis if confirmed in future studies. However, choice of IFNβ preparation still remains the single most significant determinant for the risk of developing NAbs.

Differential expression, and genetic association, of CD58 in Swedish multiple sclerosis patients

We report additional genetic and transcriptomic evidence for the role of CD58 (LFA-3) in multiple sclerosis (MS) susceptibility using a Swedish case-control material, with a result that closely mimics that of De Jager et al. (1). This gene was originally selected for further assessment because of implications in MS susceptibility (2), and because of reduced expression in the cerebrospinal fluid (CSF) of MS patients compared to controls investigated using the Affymetrix Human Genome U133 plus 2 arrays, where 2 probe sets for CD58 detected fold changes of 0.65–0.8 (P = 3.1 × 10−3 and 4.4 × 10−2). The current study included 1,077 patients and 1,217 blood-donor controls, all residing in the Stockholm area and of Scandinavian ancestry. Markers from HapMap Phase II were selected to capture most variance around CD58, and Sequenom methodology was utilized to assess genotypes at 12 SNPs. Association was tested by using logistic regression in R, validating the association of several CD58 SNPs. Most notably, the strongest effect was seen by the correlated (r2 of 0.52) alleles rs10924103G and rs12044852A, in analogy with previous results (1), showing odds ratios of 0.73 and 0.72 in multiplicative models (P = 8.3 × 10−5 and 4.3 × 10−4) and an etiological fraction of 45%. Thus, we are able to contribute to the knowledge of CD58 in MS by, in a Swedish material, reporting lowered expression of this costimulatory molecule in the CSF of MS patients, and confirming the genetic association.