Genetic Determinants of Antibody Levels in Cerebrospinal Fluid in Multiple Sclerosis: Possible Links to Endogenous Retroviruses.

The pathogenesis of multiple sclerosis (MS) has not been clarified. In addition to environmental factors; genetic determinants have been implicated in the pathogenesis of MS. Furthermore, endogenous retroviruses (ERV) might play a role in MS. The presence of oligoclonal immunoglobulin in cerebrospinal fluid (CSF) is a typical feature of MS. Recently, genetic polymorphisms in loci on human chromosomes 6, 14 and 18 have been identified as major determinants of CSF antibody levels in MS. The functional relevance of these single nucleotide polymorphisms (SNPs) remains unclear and none of them is located in an open reading frame. In previous studies, we identified ERV sequences in the vicinity of MS associated SNPs. Here, we describe the identification of ERV sequences in the neighborhood of SNPs associated with CSF antibody levels. All of the identified SNPs are located in the vicinity of ERV sequences. One of these sequences has very high homology to a sequence derived from the so-called MS-associated retrovirus (MSRV). Another cluster of three ERV sequences from the immunoglobulin heavy chain locus has retained the typical organization of retroviral genomes. These observations might shed new light on a possible association between ERVs and MS pathogenesis.

Conversion from clinically isolated syndrome to multiple sclerosis: A large multicentre study.

BACKGROUND AND OBJECTIVE: We explored which clinical and biochemical variables predict conversion from clinically isolated syndrome (CIS) to clinically definite multiple sclerosis (CDMS) in a large international cohort. METHODS: Thirty-three centres provided serum samples from 1047 CIS cases with at least two years' follow-up. Age, sex, clinical presentation, T2-hyperintense lesions, cerebrospinal fluid (CSF) oligoclonal bands (OCBs), CSF IgG index, CSF cell count, serum 25-hydroxyvitamin D3 (25-OH-D), cotinine and IgG titres against Epstein-Barr nuclear antigen 1 (EBNA-1) and cytomegalovirus were tested for association with risk of CDMS. RESULTS: At median follow-up of 4.31 years, 623 CIS cases converted to CDMS. Predictors of conversion in multivariable analyses were OCB (HR = 2.18, 95% CI = 1.71-2.77, p < 0.001), number of T2 lesions (two to nine lesions vs 0/1 lesions: HR = 1.97, 95% CI = 1.52-2.55, p < 0.001; >9 lesions vs 0/1 lesions: HR = 2.74, 95% CI = 2.04-3.68, p < 0.001) and age at CIS (HR per year inversely increase = 0.98, 95% CI = 0.98-0.99, p < 0.001). Lower 25-OH-D levels were associated with CDMS in univariable analysis, but this was attenuated in the multivariable model. OCB positivity was associated with higher EBNA-1 IgG titres. CONCLUSIONS: We validated MRI lesion load, OCB and age at CIS as the strongest independent predictors of conversion to CDMS in this multicentre setting. A role for vitamin D is suggested but requires further investigation.

Burden of risk variants correlates with phenotype of multiple sclerosis.

BACKGROUND: More than 100 common variants underlying multiple sclerosis (MS) susceptibility have been identified, but their effect on disease phenotype is still largely unknown. OBJECTIVE: The objective of this paper is to assess whether the cumulative genetic risk score of currently known susceptibility variants affects clinical presentation. METHODS: A cumulative genetic risk score was based on four human leukocyte antigen (HLA) and 106 non-HLA risk loci genotyped or imputed in 842 Belgian MS patients and 321 controls. Non-parametric analyses were applied. RESULTS: An increased genetic risk is observed for MS patients, including subsets such as oligoclonal band-negative and primary progressive MS patients, compared to controls. Within the patient group, a stronger association between HLA risk variants and the presence of oligoclonal bands, an increased immunoglobulin G (IgG) index and female gender was apparent. Results suggest an association between a higher accumulation of non-HLA risk variants and increased relapse rate as well as shorter relapse-free intervals after disease onset. CONCLUSION: MS patients display a significantly increased genetic risk compared to controls, irrespective of disease course or presence of oligoclonal bands. Whereas the cumulative burden of non-HLA risk variants appears to be reflected in the relapses of MS patients, the HLA region influences intrathecal IgG levels.

Association of HLA-DRB1*15 allele and CSF oligoclonal bands in a Spanish multiple sclerosis cohort.

BACKGROUND AND OBJECTIVE: The HLA-DRB1*15 allele is consistently associated with multiple sclerosis (MS) susceptibility in most studied populations. This study investigated the association between HLA-DRB1 alleles and the presence of oligoclonal immunoglobulin G bands (OCB) in the cerebrospinal fluid (CSF) in a Spanish population with MS. METHODS: The HLA-DRB1 typing was performed in 268 patients with sporadic MS and the detection of OCB in CSF. HLA-DRB1 allelic frequencies were compared between OCB-positive and OCB-negative patients, and both groups were also compared with 1088 unrelated healthy controls. Moreover, we correlated the various HLA-DRB1 genotypes, considering all the combinations of both parental alleles found with the presence or absence of OCB. RESULTS: We found 206 OCB-positive and 62 OCB-negative patients. The HLA-DRB1*15 allele in OCB-positive patients had a higher frequency when compared with OCB-negative patients (39.3% in OCB-positive vs. 16.1% in OCB-negative, OR = 1.38 95% CI = 1.18-1.61, P < 0.001). The other alleles did not show differences. When we compared with controls, the HLA-DRB1*15 allele was associated with the disease only in the OCB-positive patients group. None of the 55 genotypes found showed any association with the presence or absence of OCB. CONCLUSIONS: HLA-DRB1*15 allele is associated with OCB-positive patients with MS when studying a Spanish MS population.

Oligoclonal Bands in Cerebrospinal Fluid of Black Patients with Multiple Sclerosis.

Genetic susceptibility is a well-recognized factor in the onset of multiple sclerosis (MS). The objective of this study was to determine the frequency of oligoclonal bands (OCB) restricted to the cerebrospinal fluid, in an ethnically mixed group of MS patients in the city of São Paulo, Brazil. Techniques used to detect OCB consisted of isoelectric focusing followed by immunoblotting. OCB were found in 49 (54.4%) out of 90 patients with clinically definite MS; out of the 23 brown/black patients, 17 (73.9%) were OCB+; out of the 66 white patients, 32 (48.5%) were OCB+; and the only patient yellow was OCB+ (p = 0.05). Analysis of the IgG index was also consistent with the findings, but with lower statistical significance. The data presented in our study show that the ethnic differences in MS extend to the immune response.

Oligoclonal band phenotypes in MS differ in their HLA class II association, while specific KIR ligands at HLA class I show association to MS in general.

Multiple sclerosis (MS) patients have been reported to have different HLA class II allele profiles depending on oligoclonal bands (OCBs) in the cerebrospinal fluid, but HLA class I alleles and killer cell immunoglobulin-like receptor (KIR) ligands have not been studied. We investigated the association of HLA alleles and KIR ligands according to OCB status in MS patients (n=3876). Specific KIR ligands were associated with patients when compared to controls (n=3148), supporting a role for NK cells in MS pathogenesis. HLA class I alleles and KIR ligands did not differ between OCB phenotypes, but HLA class II associations were convincingly replicated.

Oligoclonal band status in Scandinavian multiple sclerosis patients is associated with specific genetic risk alleles.

The presence of oligoclonal bands (OCB) in cerebrospinal fluid (CSF) is a typical finding in multiple sclerosis (MS). We applied data from Norwegian, Swedish and Danish (i.e. Scandinavian) MS patients from a genome-wide association study (GWAS) to search for genetic differences in MS relating to OCB status. GWAS data was compared in 1367 OCB positive and 161 OCB negative Scandinavian MS patients, and nine of the most associated SNPs were genotyped for replication in 3403 Scandinavian MS patients. HLA-DRB1 genotypes were analyzed in a subset of the OCB positive (n = 2781) and OCB negative (n = 292) MS patients and compared to 890 healthy controls. Results from the genome-wide analyses showed that single nucleotide polymorphisms (SNPs) from the HLA complex and six other loci were associated to OCB status. In SNPs selected for replication, combined analyses showed genome-wide significant association for two SNPs in the HLA complex; rs3129871 (p = 5.7×10(-15)) and rs3817963 (p = 5.7×10(-10)) correlating with the HLA-DRB1*15 and the HLA-DRB1*04 alleles, respectively. We also found suggestive association to one SNP in the Calsyntenin-2 gene (p = 8.83×10(-7)). In HLA-DRB1 analyses HLA-DRB1*15∶01 was a stronger risk factor for OCB positive than OCB negative MS, whereas HLA-DRB1*04∶04 was associated with increased risk of OCB negative MS and reduced risk of OCB positive MS. Protective effects of HLA-DRB1*01∶01 and HLA-DRB1*07∶01 were detected in both groups. The groups were different with regard to age at onset (AAO), MS outcome measures and gender. This study confirms both shared and distinct genetic risk for MS subtypes in the Scandinavian population defined by OCB status and indicates different clinical characteristics between the groups. This suggests differences in disease mechanisms between OCB negative and OCB positive MS with implications for patient management, which need to be further studied.

Comparison of two methods for the detection of oligoclonal bands in a large number of clinically isolated syndrome and multiple sclerosis patients.

OBJECTIVE: A novel oligoclonal band (OB) assay which consists of isoelectric focusing (IEF) and IgG immunodetection by alkaline phosphatase-labeled anti IgG antibody was reported to be very sensitive. It also accurately predicted conversion to MS in patients with CIS. The aim of our study was to compare sensitivity of a novel and the standard procedure with peroxidase immunodetection in a large number of CIS and MS patients. METHODS: OB were determined in serum and CSF samples in 161 patients (104 females), 47 with CIS and 114 with MS with median age 38 years (range 19-68) using both methods. RESULTS: Eighty-three percent of patients had CSF OB with the standard and 89% with the novel method. Median number of OB was 5 (range 0-17) with the peroxidase and 8 (range 0-18) with the alkaline phosphatase method; p = 0.001. Twenty-one percent of patients had ≥ 10 OB with the standard and 37% with the novel method of the detection; p = 0.021. Subjective impression of band clarity showed that 20% of patients had sharper and stronger bands when the peroxidase and 65% when the alkaline phosphatase method was used; p<0.0001. CONCLUSION: The alkaline phosphatase method is more sensitive than the peroxidase method and at the same time cheaper, easy to perform and less time consuming.

Biomarkers of disease activity in multiple sclerosis.

As therapeutic options for multiple sclerosis widen, validated biomarkers of clinical disease activity are urgently needed. Reliable biomarkers would assist in choosing initial therapy, monitoring response to therapy, detecting subclinical disease activity, predicting and possibly preventing therapeutic failure, and hopefully improving both short (relapses) and long-term (disability) outcomes. The presence of oligoclonal bands in the cerebrospinal fluid is a well-validated biomarker that is useful in initial diagnosis. Neutralizing antibodies to interferon-beta are also useful in identifying treatment failure and possibly guiding changes in therapy. The discovery of antibodies to aquaporin-4 in patients with neuromyelitis optica delineates patients with a fundamentally different underlying pathophysiology and clinical course who may require alternate therapeutic approaches. While numerous other candidate biomarkers in serum and cerebrospinal fluid have been described, none so far have the validated reliability necessary for widespread clinical use. The availability of multiple genetic and protein microarray technology may assist in identifying more reliable candidate biomarkers or patterns of multiple biomarkers and improve specificity. The heterogeneity of multiple sclerosis may necessitate individualized biomarkers and therapeutic decisions within distinct subsets of patients.

Matching of oligoclonal immunoglobulin transcriptomes and proteomes of cerebrospinal fluid in multiple sclerosis.

We describe a method for correlating the immunoglobulin (Ig) proteomes with the B cell transcriptomes in human fluid and tissue samples, using multiple sclerosis as a paradigm. Oligoclonal Ig bands and elevated numbers of clonally expanded B cells in the cerebrospinal fluid (CSF) are diagnostic hallmarks of multiple sclerosis. Here we compared the Ig transcriptomes of B cells with the corresponding Ig proteomes in CSF samples from four subjects with multiple sclerosis. We created individual Ig transcriptome databases that contained the subject-specific mutations introduced by V(D)J recombination and somatic hypermutation and then searched the CSF for corresponding characteristic peptides by mass spectrometry. In each sample, the Ig transcriptomes and proteomes strongly overlapped, showing that CSF B cells indeed produce the oligoclonal Ig bands. This approach can be applied to other organ-specific diagnostic fluid or tissue samples to compare the Ig transcripts of local B cells with the corresponding antibody proteomes of individual subjects.

A linkage study in two families with multiple sclerosis and healthy members with oligoclonal CSF immunopathy.

We studied two extended families in which not only multiple sclerosis (MS) segregates, but also approximately 18% of the cerebrospinal fluid (CSF) investigated blood relatives have 'MS immunopathic trait', an oligoclonal CSF immunopathy similar to that seen in MS, but with no neurological symptoms. Both families fit a genetic model for autosomal dominant inheritance for MS immunopathic trait, although with reduced penetrance in family A. In order to identify genetic factors of importance for the development of MS immunopathic trait, we performed a genome scan using the CHLC/Weber Screening Set (ver 6A), with 285 successful markers, to test the hypothesis that a single gene is causing the MS immunopathic trait in these families. Using a parametric method, we identified regions with suggestive linkage at chromosome 6q12 with a LOD-score of 2.4, putative linkage with LOD-score 1.5 at chromosome 6p21 (HLA region), putative linkage at chromosome 12q24 with a LOD-score of 1.7 and suggestive linkage at chromosome 19q13.2 with a LOD-score of 1.8. The LOD-score at chromosome 19q13.2 increased to 2.2 when only family A was analysed. In family A, all MS patients and two of five individuals with MS immunopathic trait had HLA DRB1*(15) and in family B, all blood relatives had the rare HLA type DRB1*0103, which is associated with other autoimmune diseases. We suggest that DRB1*0103 is a necessary but not sufficient condition for the susceptibility for MS immunopathic trait in this family.