Regulation of the programmed cell death protein 1/programmed cell death ligand 1 axis in relapsing-remitting multiple sclerosis.

The programmed cell death protein 1/programmed cell death ligand 1 axis plays an important role in the adaptive immune system and has influence on neoplastic and inflammatory diseases, while its role in multiple sclerosis is unclear. Here, we aimed to analyse expression patterns of programmed cell death protein 1 and programmed cell death ligand 1 on peripheral blood mononuclear cells and their soluble variants in multiple sclerosis patients and controls, to determine their correlation with clinical disability and disease activity. In a cross-sectional study, we performed in-depth flow cytometric immunophenotyping of peripheral blood mononuclear cells and analysed soluble programmed cell death protein 1 and programmed cell death ligand 1 serum levels in patients with relapsing-remitting multiple sclerosis and controls. In comparison to control subjects, relapsing-remitting multiple sclerosis patients displayed distinct cellular programmed cell death protein 1/programmed cell death ligand 1 expression patterns in immune cell subsets and increased soluble programmed cell death ligand 1 levels, which correlated with clinical measures of disability and MRI activity over time. This study extends our knowledge of how programmed cell death protein 1 and programmed cell death ligand 1 are expressed in the membranes of patients with relapsing-remitting multiple sclerosis and describes for the first time the elevation of soluble programmed cell death ligand 1 in the blood of multiple sclerosis patients. The distinct expression pattern of membrane-bound programmed cell death protein 1 and programmed cell death ligand 1 and the correlation between soluble programmed cell death ligand 1, membrane-bound programmed cell death ligand 1, disease and clinical factors may offer therapeutic potential in the setting of multiple sclerosis and might improve future diagnosis and clinical decision-making.

The Aryl Hydrocarbon Receptor-Dependent TGF-α/VEGF-B Ratio Correlates With Disease Subtype and Prognosis in Multiple Sclerosis.

OBJECTIVE: To evaluate the aryl hydrocarbon receptor (AHR)-dependent transforming growth factor alpha (TGF-α)/vascular endothelial growth factor B (VEGF-B) ratio, which regulates the effects of metabolic, dietary, and microbial factors on acute and chronic CNS inflammation, as a potential marker in multiple sclerosis (MS). METHODS: TGF-α, VEGF-B, and AHR agonistic activity were determined in serum of 252 patients with relapsing-remitting (RR) MS, primary and secondary progressive MS, as well as during active disease (clinically isolated syndrome [CIS] and RRMS relapse). RESULTS: The TGF-α/VEGF-B ratio and AHR agonistic activity were decreased in all MS subgroups with a stable disease course as compared to controls. During active CNS inflammation in CIS and RRMS relapse, the TGF-α/VEGF-B ratio and AHR agonistic activity were increased. Conversely, in patients with minimal clinical impairment despite long-standing disease, the TGF-α/VEGF-B ratio and AHR agonistic activity were unaltered. Finally, the TGF-α/VEGF-B ratio and AHR agonistic activity correlated with neurologic impairment and time to conversion from CIS to MS. CONCLUSIONS: The AHR-dependent TGF-α/VEGF-B ratio is altered in a subtype, severity, and disease activity-specific manner and correlates with time to conversion from CIS to MS. It may thus represent a novel marker and serve as additive guideline for immunomodulatory strategies in MS. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that serum levels of AHR, TGF-α, and VEGF-B distinguish subtypes of MS and predict the severity and disease activity of MS.

Aryl Hydrocarbon Receptor Plasma Agonist Activity Correlates With Disease Activity in Progressive MS.

OBJECTIVE: The relationship between serum aryl hydrocarbon receptor (AHR) agonistic activity levels with disease severity, its modulation over the course of relapsing-remitting MS (RRMS), and its regulation in progressive MS (PMS) are unknown. Here, we report the analysis of AHR agonistic activity levels in cross-sectional and longitudinal serum samples of patients with RRMS and PMS. METHODS: In a cross-sectional investigation, a total of 36 control patients diagnosed with noninflammatory diseases, 84 patients with RRMS, 35 patients with secondary progressive MS (SPMS), and 41 patients with primary progressive MS (PPMS) were included in this study. AHR activity was measured in a cell-based luciferase assay and correlated with age, sex, the presence of disease-modifying therapies, Expanded Disability Status Scale scores, and disease duration. In a second longitudinal investigation, we analyzed AHR activity in 13 patients diagnosed with RRMS over a period from 4 to 10 years and correlated AHR agonistic activity with white matter atrophy and lesion load volume changes. RESULTS: In RRMS, AHR ligand levels were globally decreased and associated with disease duration and neurologic disability. In SPMS and PPMS, serum AHR agonistic activity was decreased and correlated with disease severity. Finally, in longitudinal serum samples of patients with RRMS, decreased AHR agonistic activity was linked to progressive CNS atrophy and increased lesion load. CONCLUSIONS: These findings suggest that serum AHR agonist levels negatively correlate with disability in RRMS and PMS and decrease longitudinally in correlation with MRI markers of disease progression. Thus, serum AHR agonistic activity may serve as novel biomarker for disability progression in MS.

Treatment- and population-specific genetic risk factors for anti-drug antibodies against interferon-beta: a GWAS.

BACKGROUND: Upon treatment with biopharmaceuticals, the immune system may produce anti-drug antibodies (ADA) that inhibit the therapy. Up to 40% of multiple sclerosis patients treated with interferon ß (IFNß) develop ADA, for which a genetic predisposition exists. Here, we present a genome-wide association study on ADA and predict the occurrence of antibodies in multiple sclerosis patients treated with different interferon ß preparations. METHODS: We analyzed a large sample of 2757 genotyped and imputed patients from two cohorts (Sweden and Germany), split between a discovery and a replication dataset. Binding ADA (bADA) levels were measured by capture-ELISA, neutralizing ADA (nADA) titers using a bioassay. Genome-wide association analyses were conducted stratified by cohort and treatment preparation, followed by fixed-effects meta-analysis. RESULTS: Binding ADA levels and nADA titers were correlated and showed a significant heritability (47% and 50%, respectively). The risk factors differed strongly by treatment preparation: The top-associated and replicated variants for nADA presence were the HLA-associated variants rs77278603 in IFNß-1a s.c.- (odds ratio (OR) = 3.55 (95% confidence interval = 2.81-4.48), p = 2.1 × 10-26) and rs28366299 in IFNß-1b s.c.-treated patients (OR = 3.56 (2.69-4.72), p = 6.6 × 10-19). The rs77278603-correlated HLA haplotype DR15-DQ6 conferred risk specifically for IFNß-1a s.c. (OR = 2.88 (2.29-3.61), p = 7.4 × 10-20) while DR3-DQ2 was protective (OR = 0.37 (0.27-0.52), p = 3.7 × 10-09). The haplotype DR4-DQ3 was the major risk haplotype for IFNß-1b s.c. (OR = 7.35 (4.33-12.47), p = 1.5 × 10-13). These haplotypes exhibit large population-specific frequency differences. The best prediction models were achieved for ADA in IFNß-1a s.c.-treated patients. Here, the prediction in the Swedish cohort showed AUC = 0.91 (0.85-0.95), sensitivity = 0.78, and specificity = 0.90; patients with the top 30% of genetic risk had, compared to patients in the bottom 30%, an OR = 73.9 (11.8-463.6, p = 4.4 × 10-6) of developing nADA. In the German cohort, the AUC of the same model was 0.83 (0.71-0.92), sensitivity = 0.80, specificity = 0.76, with an OR = 13.8 (3.0-63.3, p = 7.5 × 10-4). CONCLUSIONS: We identified several HLA-associated genetic risk factors for ADA against interferon ß, which were specific for treatment preparations and population backgrounds. Genetic prediction models could robustly identify patients at risk for developing ADA and might be used for personalized therapy recommendations and stratified ADA screening in clinical practice. These analyses serve as a roadmap for genetic characterizations of ADA against other biopharmaceutical compounds.

Cytokine and immune cell profiling in the cerebrospinal fluid of patients with neuro-inflammatory diseases.

BACKGROUND: Cytokines play multiple roles during neuro-inflammatory processes and several cytokines have been studied in the context of specific diseases. This study provides a comprehensive picture of cerebrospinal fluid (CSF) changes during neuro-inflammation by analyzing multiple cytokines in combination with immune cell subsets and standard CSF parameters. METHODS: Using multiplex assays, we simultaneously measured 36 cytokines (CCL1-3, CCL7, CCL8, CCL11, CCL13, CCL19, CCL20, CCL22-27, CXCL1, CXCL2, CXCL5, CXCL6, CXCL8, CXCL9, CXCL11-13, CXCL16, CX3CL1, IL2, IL4, IL6, IL10, IL16, GM-CSF, IFNγ, MIF, TNFα, and MIB1ß) in the CSF and serum of 75 subjects. Diagnoses included clinically isolated syndrome and relapsing-remitting multiple sclerosis (MS, n = 18), secondary progressive MS (n = 8), neuro-syphilis (n = 6), Lyme neuro-borreliosis (n = 13), bacterial and viral meningitis (n = 20), and patients with non-inflammatory neurological diseases (NIND, n = 10). Cytokine concentrations were correlated with CSF standard parameters and CSF immune cell subsets (CD4 and CD8 T cells, B cells, plasmablasts, monocytes, and NK cells) quantified by flow cytometry. RESULTS: We observed increased levels of multiple cytokines (26/36) in patients with neuro-inflammatory diseases when compared to NIND that consistently correlated with CSF cell count and QAlbumin. Most CSF cytokine concentrations correlated with each other, but correlations between CSF and serum values were scarce (3/36). Within the CSF compartment, CXCL13 showed a strong association with B cells when analyzing all patients, as well as patients with an intact blood-brain barrier (BBB). NK cells positively correlated with CSF concentrations of multiple cytokines (22/36) when analyzing all patients. These correlations were maintained when looking at patients with a disrupted BBB but not detectable in patients with an intact BBB. CONCLUSIONS: Under conditions of neuro-inflammation, multiple CSF cytokines are regulated in parallel and most likely produced locally. A combined increase of CSF CXCL13 levels and B cells occurs under conditions of an intact BBB. Under conditions of a disrupted BBB, CSF NK cells show significantly increased values and seem to have a major contribution to overall inflammatory processes, reflected by a strong correlation with multiple cytokines. Future studies are necessary to address the exact kinetics of these cytokines during neuro-inflammation and their relation to specific diseases phenotypes.

Detection and kinetics of persistent neutralizing anti-interferon-beta antibodies in patients with multiple sclerosis. Results from the ABIRISK prospective cohort study.

Two validated assays, a bridging ELISA and a luciferase-based bioassay, were compared for detection of anti-drug antibodies (ADA) against interferon-beta (IFN-ß) in patients with multiple sclerosis. Serum samples were tested from patients enrolled in a prospective study of 18 months. In contrast to the ELISA, when IFN-ß-specific rabbit polyclonal and human monoclonal antibodies were tested, the bioassay was the more sensitive to detect IFN-ß ADA in patients' sera. For clinical samples, selection of method of ELISA should be evaluated prior to the use of a multi-tiered approach. A titer threshold value is reported that may be used as a predictor for persistently positive neutralizing ADA.

Interferon-beta specific T cells are associated with the development of neutralizing antibodies in interferon-beta treated multiple sclerosis patients.

Beta-interferons are still among the most commonly used drugs to treat Multiple Sclerosis (MS). The use of beta-interferons is limited by the development of anti-drug antibodies (ADA), which may abrogate the treatment effect of the drug. Although the antibody response has been well studied, little is known about the T cell response to interferon-beta (IFN-ß). We investigated T cell responses in four treatment naïve MS patients and twenty-three patients treated with IFN-ß who had or had not developed ADA to IFN-ß. T cell responses were determined by split-well and primary proliferation assays against different IFN-ß protein preparations and a set of overlapping peptides covering the full sequence of IFN-ß. T cell responses to IFN-ß were observed in all donors. ADA positive patients showed higher T cell responses to IFN-ß protein than ADA negative patients and untreated controls. We identified two immunodominant regions; T cell responses to IFN-ß1-40 were observed in all patients independent of ADA status, while T cell responses to IFN-ß125-159 were stronger in ADA positive than ADA negative patients. IFN-ß specific T cell responses were HLA class II restricted and in ADA positive patients skewed towards a Th2 phenotype. In IFN-ß treated patients we observed a correlation between IFN-ß specific T cell responses, serum ADA titer and loss of biological activity of IFN-ß treatment. Our studies demonstrate the occurrence of an antigen specific HLA class II restricted Th2 T cell response associated with the development of ADA in IFN-ß treated patients.

Clinical practice of analysis of anti-drug antibodies against interferon beta and natalizumab in multiple sclerosis patients in Europe: A descriptive study of test results.

Antibodies against biopharmaceuticals (anti-drug antibodies, ADA) have been a well-integrated part of the clinical care of multiple sclerosis (MS) in several European countries. ADA data generated in Europe during the more than 10 years of ADA monitoring in MS patients treated with interferon beta (IFNß) and natalizumab have been pooled and characterized through collaboration within a European consortium. The aim of this study was to report on the clinical practice of ADA testing in Europe, considering the number of ADA tests performed and type of ADA assays used, and to determine the frequency of ADA testing against the different drug preparations in different countries. A common database platform (tranSMART) for querying, analyzing and storing retrospective data of MS cohorts was set up to harmonize the data and compare results of ADA tests between different countries. Retrospective data from six countries (Sweden, Austria, Spain, Switzerland, Germany and Denmark) on 20,695 patients and on 42,555 samples were loaded into tranSMART including data points of age, gender, treatment, samples, and ADA results. The previously observed immunogenic difference among the four IFNß preparations was confirmed in this large dataset. Decreased usage of the more immunogenic preparations IFNß-1a subcutaneous (s.c.) and IFNß-1b s.c. in favor of the least immunogenic preparation IFNß-1a intramuscular (i.m.) was observed. The median time from treatment start to first ADA test correlated with time to first positive test. Shorter times were observed for IFNß-1b-Extavia s.c. (0.99 and 0.94 years) and natalizumab (0.25 and 0.23 years), which were introduced on the market when ADA testing was already available, as compared to IFNß-1a i.m. (1.41 and 2.27 years), IFNß-1b-Betaferon s.c. (2.51 and 1.96 years) and IFNß-1a s.c. (2.11 and 2.09 years) which were available years before routine testing began. A higher rate of anti-IFNß ADA was observed in test samples taken from older patients. Testing for ADA varies between different European countries and is highly dependent on the policy within each country. For drugs where routine monitoring of ADA is not in place, there is a risk that some patients remain on treatment for several years despite ADA positivity. For drugs where a strategy of ADA testing is introduced with the release of the drug, there is a reduced risk of having ADA positive patients and thus of less efficient treatment. This indicates that potential savings in health cost might be achieved by routine analysis of ADA.

Occurrence of Anti-Drug Antibodies against Interferon-Beta and Natalizumab in Multiple Sclerosis: A Collaborative Cohort Analysis.

Immunogenicity of biopharmaceutical products in multiple sclerosis is a frequent side effect which has a multifactorial etiology. Here we study associations between anti-drug antibody (ADA) occurrence and demographic and clinical factors. Retrospective data from routine ADA test laboratories in Sweden, Denmark, Austria and Germany (Dusseldorf group) and from one research study in Germany (Munich group) were gathered to build a collaborative multi-cohort dataset within the framework of the ABIRISK project. A subset of 5638 interferon-beta (IFNß)-treated and 3440 natalizumab-treated patients having data on at least the first two years of treatment were eligible for interval-censored time-to-event analysis. In multivariate Cox regression, IFNß-1a subcutaneous and IFNß-1b subcutaneous treated patients were at higher risk of ADA occurrence compared to IFNß-1a intramuscular-treated patients (pooled HR = 6.4, 95% CI 4.9-8.4 and pooled HR = 8.7, 95% CI 6.6-11.4 respectively). Patients older than 50 years at start of IFNß therapy developed ADA more frequently than adult patients younger than 30 (pooled HR = 1.8, 95% CI 1.4-2.3). Men developed ADA more frequently than women (pooled HR = 1.3, 95% CI 1.1-1.6). Interestingly we observed that in Sweden and Germany, patients who started IFNß in April were at higher risk of developing ADA (HR = 1.6, 95% CI 1.1-2.4 and HR = 2.4, 95% CI 1.5-3.9 respectively). This result is not confirmed in the other cohorts and warrants further investigations. Concerning natalizumab, patients older than 45 years had a higher ADA rate (pooled HR = 1.4, 95% CI 1.0-1.8) and women developed ADA more frequently than men (pooled HR = 1.4, 95% CI 1.0-2.0). We confirmed previously reported differences in immunogenicity of the different types of IFNß. Differences in ADA occurrence by sex and age are reported here for the first time. These findings should be further investigated taking into account other exposures and biomarkers.

Potassium channel KIR4.1-specific antibodies in children with acquired demyelinating CNS disease.

OBJECTIVE: A serum antibody against the inward rectifying potassium channel KIR4.1 (KIR4.1-IgG) was recently discovered, which is found in almost half of adult patients with multiple sclerosis. We investigated the prevalence of KIR4.1-IgG in children with acquired demyelinating disease (ADD) of the CNS. We also compared antibody responses to KIR4.1 and myelin oligodendrocyte glycoproteins (MOGs), another potential autoantigen in childhood ADDs. METHODS: We measured KIR4.1-IgG by ELISA in children with ADD (n = 47), other neurologic disease (n = 22), and autoimmune disease (n = 22), and in healthy controls (HCs) (n = 18). One hundred six samples were also measured by capture ELISA. Binding of KIR4.1-IgG human subcortical white matter was analyzed by immunofluorescence. Anti-MOG antibodies were measured using a cell-based assay. RESULTS: KIR4.1-IgG titers were significantly higher in children with ADD compared with all control groups by ELISA and capture ELISA (p < 0.0001, p < 0.0001). Overall, 27 of 47 patients with ADD (57.45%) but none of the 62 with other neurologic disease or autoimmune disease or the HCs (0%) were KIR4.1-IgG antibody positive by ELISA. Sera containing KIR4.1-IgG stained glial cells in brain tissue sections. No correlation among KIR4.1-IgG, age, or MOG-IgG was observed in the ADD group. CONCLUSION: Serum antibodies to KIR4.1 are found in the majority of children with ADD but not in children with other diseases or in HCs. These findings suggest that KIR4.1 is an important target of autoantibodies in childhood ADD.

Natalizumab treatment decreases serum IgM and IgG levels in multiple sclerosis patients.

BACKGROUND: Treatment with natalizumab, a humanized monoclonal antibody against alpha4beta1 integrin, is associated with an increase in lymphoid progenitor cells and B cells in peripheral blood. OBJECTIVE: The objective of this study was to examine the impact of natalizumab therapy on serum levels of total IgG, IgA and IgM in patients with multiple sclerosis (MS). METHODS: In two independent cross-sectional patient cohorts, serum levels of IgG, IgA and IgM were compared between patients treated with natalizumab and those not receiving natalizumab. Further, serum levels of IgG, IgA and IgM before and during natalizumab treatment were compared in two longitudinal patient cohorts. RESULTS: In patients treated with natalizumab, serum IgM and IgG levels were significantly lower compared with therapy naïve patients (p<0.0001). IgM levels significantly decreased after initiation of natalizumab treatment in both longitudinal patient cohorts (p<0.01). Moreover, patients treated with natalizumab showed a time-dependent decrease in IgM levels during the first 2 years of treatment. CONCLUSION: Natalizumab treatment leads to a significant decrease in serum IgM and IgG levels in patients with MS. IgM levels decrease with treatment duration during the first 2 years of treatment. These findings might support the hypothesis that natalizumab interferes with homing of B cells, possibly leading to impaired differentiation into plasma cells and subsequently disturbed immunoglobulin synthesis.

Genetic variants in the immunoglobulin heavy chain locus are associated with the IgG index in multiple sclerosis.

OBJECTIVE: Intrathecal synthesis of immunoglobulin gamma (IgG) synthesis is frequently observed in patients with multiple sclerosis (MS). Whereas the extent of intrathecal IgG synthesis varies largely between patients, it remains rather constant in the individual patient over time. The aim of this study was to identify common genetic variants associated with the IgG index as a marker of intrathecal IgG synthesis in MS. METHODS: We performed a genome-wide association study of the IgG index in a discovery series of 229 patients. For confirmation we performed a replication in 2 independent series comprising 256 and 153 patients, respectively. The impact of associated single nucleotide polymorphisms (SNPs) on MS susceptibility was analyzed in an additional 1,854 cases and 5,175 controls. RESULTS: Significant association between the IgG index and 5 SNPs was detected in the discovery and confirmed in both replication series reaching combined p values of p = 6.5 × 10(-11) to p = 7.5 × 10(-16) . All identified SNPs are clustered around the immunoglobulin heavy chain (IGHC) locus on chromosome 14q32.33 and are in linkage disequilibrium (r(2) range, 0.71-0.95). The best associated SNP is located in an intronic region of the immunoglobulin gamma3 heavy chain gene. Additional sequencing identified the GM21* haplotype to be associated with a high IgG index. Further evaluation of the IGHC SNPs revealed no association with susceptibility to MS in our data set. INTERPRETATION: The extent of intrathecal IgG in MS is influenced by the IGHC locus. No association with susceptibility to MS was found. Therefore GM haplotypes might affect intrathecal IgG synthesis independently of the underlying disease.

CXCL13 is the major determinant for B cell recruitment to the CSF during neuroinflammation.

BACKGROUND: The chemokines and cytokines CXCL13, CXCL12, CCL19, CCL21, BAFF and APRIL are believed to play a role in the recruitment of B cells to the central nervous system (CNS) compartment during neuroinflammation. To determine which chemokines/cytokines show the strongest association with a humoral immune response in the cerebrospinal fluid (CSF), we measured their concentrations in the CSF and correlated them with immune cell subsets and antibody levels. METHODS: Cytokine/chemokine concentrations were measured in CSF and serum by ELISA in patients with non-inflammatory neurological diseases (NIND, n = 20), clinically isolated syndrome (CIS, n = 30), multiple sclerosis (MS, n = 20), Lyme neuroborreliosis (LNB, n = 8) and patients with other inflammatory neurological diseases (OIND, n = 30). Albumin, IgG, IgA and IgM were measured by nephelometry. CSF immune cell subsets were determined by seven-color flow cytometry. RESULTS: CXCL13 was significantly elevated in the CSF of all patient groups with inflammatory diseases. BAFF levels were significantly increased in patients with LNB and OIND. CXCL12 was significantly elevated in patients with LNB. B cells and plasmablasts were significantly elevated in the CSF of all patients with inflammatory diseases. CXCL13 showed the most consistent correlation with CSF B cells, plasmablasts and intrathecal Ig synthesis. CONCLUSIONS: CXCL13 seems to be the major determinant for B cell recruitment to the CNS compartment in different neuroinflammatory diseases. Thus, elevated CSF CXCL13 levels rather reflect a strong humoral immune response in the CNS compartment than being specific for a particular disease entity.

The role of the Epstein-Barr virus receptor CD21 in multiple sclerosis.

Multiple Sclerosis (MS) is characterised by a chronic inflammation and demyelination of brain and spinal cord with a yet unknown aetiology. Based on multiple epidemiological and immunological studies, which suggest a role of Epstein-Barr virus (EBV) infection in the pathogenesis of MS, we investigated CD21 (CR2, complement receptor type 2), which serves as the EBV receptor. Serum concentrations of soluble CD21 receptor (sCD21) were determined in MS patients and controls. In accordance with findings in other autoimmune disorders decreased sCD21 levels were found in MS patients. On ß-IFN treatment serum sCD21 concentrations further decreased. To explore the role of the CD21 gene for MS susceptibility and the altered CD21 levels in MS patients we performed exon sequencing of the CD21 gene. While we identified new single nucleotide polymorphism (SNP) and confirmed previously reported SNPs, none of the SNPs was associated with MS. Our findings demonstrate that sCD21 expression is altered in MS patients similar to other autoimmune diseases although no evidence was found for a specific role of the CD21 gene in MS.

Influence of the HLA-DRB1 genotype on antibody development to interferon beta in multiple sclerosis.

OBJECTIVE: To determine relevant HLA-DRB1 alleles associated with the susceptibility of anti-interferon beta antibody development in a large patient cohort. DESIGN: In a case-control study, HLA-DRB1 genotyping was performed in a discovery cohort (n = 268) and a validation cohort (n = 825). SETTING: Patients were recruited in Germany by primary care physicians and neurologists and were mainly of Northern European heritage. PATIENTS: All patients had a diagnosis of multiple sclerosis and were receiving long-term interferon beta therapy. MAIN OUTCOME MEASURES: The antibody status to interferon beta was determined in all patients by capture enzyme-linked immunosorbent assay and in vivo myxovirus protein A assay and correlated with the HLA-DRB1 genotype. RESULTS: In the discovery and validation cohorts, HLA-DRB1*04:01, *04:08, *16:01 were identified as genetic markers that are associated with an increased risk of anti-interferon beta antibody development (P < .05). In addition, alleles with a protective potential were identified, including HLA-DRB1*03:01, *04:04, *11:04. However, after correction for multiple testing, protective alleles did not reach statistical significance. CONCLUSION: The HLA alleles identified in this study seem to be the major genetic determinant of antibody development, allowing the prediction of the individual risk of patients before initiation of therapy.

Antibodies to native myelin oligodendrocyte glycoprotein in children with inflammatory demyelinating central nervous system disease.

OBJECTIVE: Myelin oligodendrocyte glycoprotein (MOG) is a candidate target antigen in demyelinating diseases of the central nervous system (CNS). Although MOG is encephalitogenic in different animal models, the relevance of this antigen in human autoimmune diseases of the CNS is still controversial. METHODS: We investigated the occurrence and biological activity of antibodies to native MOG (nMOG) in 47 children during a first episode of CNS demyelination (acute disseminated encephalomyelitis [ADEM], n = 19 and clinical isolated syndrome [CIS], n = 28) by a cell-based bioassay. RESULTS: High serum immunoglobulin G (IgG) titers to nMOG were detected in 40% of children with CIS/ADEM but 0% of the control children affected by other neurological diseases, healthy children, or adults with inflammatory demyelinating diseases, respectively. By contrast, IgM antibodies to nMOG occurred in only 3 children affected by ADEM. Children with high anti-nMOG IgG titer were significantly younger than those with low IgG titer. Anti-nMOG IgG titers did not differ between the ADEM and CIS group, and did not predict conversion from CIS to MS during a mean 2-year follow-up. However, intrathecal IgG anti-MOG antibody synthesis was only seen in CIS children. IgG antibodies to nMOG not only bound to the extracellular domain of nMOG, but also induced natural killer cell-mediated killing of nMOG-expressing cells in vitro. INTERPRETATION: Overall, these findings suggest nMOG as a major target of the humoral immune response in a subgroup of children affected by inflammatory demyelinating diseases of the CNS. Children may provide valuable insight into the earliest immune mechanisms of CNS demyelination.

HLA-DRB1*0401 and HLA-DRB1*0408 are strongly associated with the development of antibodies against interferon-beta therapy in multiple sclerosis.

The formation of antibodies to interferon-beta (IFN-beta), a protein-based disease-modifying agent for multiple sclerosis (MS), is a problem in clinical practice. These antibodies may neutralize the biological effects of the protein drug, potentially decreasing its therapeutic effects. By high-resolution HLA class I and II typing we identified two HLA class II alleles associated with the development of antibodies to IFN-beta. In two independent continuous and binary-trait association studies, HLA-DRB1*0401 and HLA-DRB1*0408 (odds ratio: 5.15)--but not other HLA alleles--were strongly associated with the development of binding and neutralizing antibodies to IFN-beta. The associated HLA-DRB1*04 alleles differ from nonassociated HLA-DRB1*04 alleles by a glycine-to-valine substitution in position 86 of the epitope-binding alpha-helix of the HLA class II molecule. The peptide-binding motif of HLA-DRB1*0401 and *0408 might promote binding and presentation of an immunogenic peptide, which may eventually break T cell tolerance and facilitate antibody development to IFN-beta. In summary, we identified genetic factors determining the immunogenicity of IFN-beta, a protein-based disease-modifying agent for the treatment of MS.

Viral load determines the B-cell response in the cerebrospinal fluid during human immunodeficiency virus infection.

OBJECTIVE: Human immunodeficiency virus (HIV) infection of the central nervous system (CNS) is frequently associated with intrathecal immunoglobulin synthesis and cerebrospinal fluid (CSF) pleocytosis, but little is known about the B-cell response in the CSF of these patients. In this study, we investigated the relation between virus load and the frequency and phenotype of B cells in the CSF of HIV-infected patients. METHODS: The distribution of T cells, B cells, short-lived plasmablasts, and long-lived plasma cells was analyzed by flow cytometry in CSF and peripheral blood of 33 patients with HIV infection compared with 12 patients with noninfectious CNS diseases. HIV RNA copy number in CSF and serum was quantified by kinetic polymerase chain reaction. RESULTS: B-cell and plasmablast levels were increased in the CSF of HIV-infected patients compared with patients with noninfectious CNS diseases. Whereas CSF B cells were found at similar frequency during early and late stages of HIV infection, plasmablasts were more prevalent in the CSF during early infection. Plasmablasts in the CSF correlated with intrathecal IgG synthesis and even stronger with HIV RNA copy numbers in CSF, in particular, in untreated, early HIV-infected individuals. Initiation of antiviral treatment in therapy-naive patients strongly decreased HIV copy numbers and plasmablasts in CSF. INTERPRETATION: Our findings demonstrate that HIV infection of the CNS triggers an early profound B-cell response, with plasmablasts serving as the main virus-related B-cell subset in the CSF.

CD8 T-cell subsets and viral load in the cerebrospinal fluid of therapy-naive HIV-infected individuals.

Central nervous system involvement is common in HIV infection. We determined the relationship between T-cell subsets and viral load in the cerebrospinal fluid (CSF) of therapy-naive, asymptomatic HIV-infected individuals. A shift from naive to effector-memory CD8 T cells was observed in the CSF of HIV-infected individuals compared with controls. The HIV load strongly correlated with CD8 T cells in CSF. Effector-memory CD8 T cells were positively and effector CD8 T cells were negatively associated with viral replication in CSF.

Identification of a pathogenic antibody response to native myelin oligodendrocyte glycoprotein in multiple sclerosis.

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system. Although the cause of MS is still uncertain, many findings point toward an ongoing autoimmune response to myelin antigens. Because of its location on the outer surface of the myelin sheath and its pathogenicity in the experimental autoimmune encephalomyelitis model, myelin oligodendrocyte glycoprotein (MOG) is one of the potential disease-causing self antigens in MS. However, the role of MOG in the pathogenesis of MS has remained controversial. In this study we addressed the occurrence of autoantibodies to native MOG and its implication for demyelination and axonal loss in MS. We applied a high-sensitivity bioassay, which allowed detecting autoantibodies that bind to the extracellular part of native MOG. Antibodies, mostly IgG, were found in sera that bound with high affinity to strictly conformational epitopes of the extracellular domain of MOG. IgG but not IgM antibody titers to native MOG were significantly higher in MS patients compared with different control groups with the highest prevalence in primary progressive MS patients. Serum autoantibodies to native MOG induced death of MOG-expressing target cells in vitro. Serum from MS patients with high anti-MOG antibody titers stained white matter myelin in rat brain and enhanced demyelination and axonal damage when transferred to autoimmune encephalomyelitis animals. Overall these findings suggest a pathogenic antibody response to native MOG in a subgroup of MS patients.