Effects of anti-CD20 therapy on circulating and intrathecal follicular helper T cell subsets in multiple sclerosis.

Follicular helper T (Tfh) cells and their interplay with B cells likely contribute to the pathogenesis of relapsing-remitting multiple sclerosis (RRMS). Tfh cells are enriched in cerebrospinal fluid (CSF) in RRMS, but effects of anti-CD20 therapy are unknown. We investigated Tfh cells in controls, untreated and anti-CD20-treated patients with RRMS using flow cytometry. CSF Tfh cells were increased in untreated patients. Compared to paired blood samples, CD25- Tfh cells were enriched in CSF in RRMS, but not in controls. Contrast-enhancing brain MRI lesions and IgG index correlated with CSF CD25- Tfh cell frequency in untreated patients with RRMS. Anti-CD20 therapy reduced the numbers of circulating PD1+ Tfh cells and CD25- Tfh cells, and the frequency of CSF CD25- Tfh cells. The study suggests that CD25- Tfh cells are recruited to the CSF in RRMS, associated with focal inflammation, and are reduced by anti-CD20 therapy.

Sustained effects on immune cell subsets and autoreactivity in multiple sclerosis patients treated with oral cladribine.

Introduction: Cladribine tablet therapy is an efficacious treatment for multiple sclerosis (MS). Recently, we showed that one year after the initiation of cladribine treatment, T and B cell crosstalk was impaired, reducing potentially pathogenic effector functions along with a specific reduction of autoreactivity to RAS guanyl releasing protein 2 (RASGRP2). In the present study we conducted a longitudinal analysis of the effect of cladribine treatment in patients with RRMS, focusing on the extent to which the effects observed on T and B cell subsets and autoreactivity after one year of treatment are maintained, modulated, or amplified during the second year of treatment. Methods: In this case-control exploratory study, frequencies and absolute counts of peripheral T and B cell subsets and B cell cytokine production from untreated patients with relapsing-remitting MS (RRMS) and patients treated with cladribine for 52 (W52), 60 (W60), 72 (W72) and 96 (W96) weeks, were measured using flow cytometry. Autoreactivity was assessed using a FluoroSpot assay. Results: We found a substantial reduction in circulating memory B cells and proinflammatory B cell responses. Furthermore, we observed reduced T cell responses to autoantigens possibly presented by B cells (RASGRP2 and a-B crystallin (CRYAB)) at W52 and W96 and a further reduction in responses to the myelin antigens myelin basic protein (MBP) and myelin oligodendrocyte glycoprotein (MOG) after 96 weeks. Conclusion: We conclude that the effects of cladribine observed after year one are maintained and, for some effects, even increased two years after the initiation of a full course of treatment with cladribine tablets.

CD11c+ B cells in relapsing-remitting multiple sclerosis and effects of anti-CD20 therapy.

OBJECTIVES: B cells are important in the pathogenesis of multiple sclerosis. It is yet unknown which subsets may be involved, but atypical B cells have been proposed as mediators of autoimmunity. In this study, we investigated differences in B-cell subsets between controls and patients with untreated and anti-CD20-treated multiple sclerosis. METHODS: We recruited 155 participants for an exploratory cohort comprising peripheral blood and cerebrospinal fluid, and a validation cohort comprising peripheral blood. Flow cytometry was used to characterize B-cell phenotypes and effector functions of CD11c+ atypical B cells. RESULTS: There were no differences in circulating B cells between controls and untreated multiple sclerosis. As expected, anti-CD20-treated patients had a markedly lower B-cell count. Of B cells remaining after treatment, we observed higher proportions of CD11c+ B cells and plasmablasts. CD11c+ B cells were expanded in cerebrospinal fluid compared to peripheral blood in controls and untreated multiple sclerosis. Surprisingly, the proportion of CD11c+ cerebrospinal fluid B cells was higher in controls and after anti-CD20 therapy than in untreated multiple sclerosis. Apart from the presence of plasmablasts, the cerebrospinal fluid B-cell composition after anti-CD20 therapy resembled that of controls. CD11c+ B cells demonstrated a high potential for both proinflammatory and regulatory cytokine production. INTERPRETATION: The study demonstrates that CD11c+ B cells and plasmablasts are less efficiently depleted by anti-CD20 therapy, and that CD11c+ B cells comprise a phenotypically and functionally distinct, albeit heterogenous, B-cell subset with the capacity of exerting both proinflammatory and regulatory functions.

Immune reconstitution following alemtuzumab therapy is characterized by exhausted T cells, increased regulatory control of proinflammatory T cells and reduced B cell control.

Alemtuzumab is a monoclonal antibody targeting CD52 on the surface of immune cells, approved for the treatment of active relapsing-remitting multiple sclerosis (RRMS). The purpose of this study was to analyze the repopulation of peripheral lymphocytes following alemtuzumab-induced lymphocyte depletion and investigate associations with disease activity and development of secondary autoimmunity. For this, blood samples were collected two years after initiation of alemtuzumab treatment and lymphocytes were subjected to a comprehensive flow cytometry analysis. Included in the study were 40 patients treated with alemtuzumab and 40 treatment-naïve patients with RRMS. Disease activity and development of secondary autoimmune disease was evaluated after three years of treatment. Our study confirms that alemtuzumab treatment profoundly alters the circulating lymphocyte phenotype and describes a reconstituted immune system characterized by T cell activation/exhaustion, an increased regulatory control of IL-17 producing effector T cells and CD20+ T cells, and a reduced control of B cells. There were no obvious associations between immune cell subsets and disease activity or development of secondary autoimmune disease during treatment with alemtuzumab. Our results indicate that the reconstituted immune response is skewed towards a more effective regulatory control of MS-associated proinflammatory T cell responses. Also, the enlarged pool of naïve B cells together with the apparent decrease in control of B cell activity may explain why alemtuzumab-treated patients retain the ability to mount a humoral immune response towards new antigens.

Citrullination of myelin basic protein induces a Th17-cell response in healthy individuals and enhances the presentation of MBP85-99 in patients with multiple sclerosis.

The post-translational modification citrullination has been proposed to play a role in the pathogenesis of multiple sclerosis (MS). Myelin basic protein (MBP) is a candidate autoantigen which is citrullinated to a minor extent under physiological conditions and hypercitrullinated in MS. We examined immune cell responses elicited by hypercitrullinated MBP (citMBP) in cultures of mononuclear cells from 18 patients with MS and 42 healthy donors (HDs). The immunodominant peptide of MBP, MBP85-99, containing citrulline in position 99, outcompeted the binding of native MBP85-99 to HLA-DR15, which is strongly linked to MS. Moreover, using the monoclonal antibody MK16 as probe, we observed that B cells and monocytes from HLA-DR15+ patients with MS presented MBP85-99 more efficiently after challenge with citMBP than with native MBP. Both citMBP and native MBP induced proliferation of CD4+ T cells from patients with MS as well as TNF-α production by their B cells and CD4+ T cells, and citrullination of MBP tended to enhance TNF-α secretion by CD4+ T cells from HLA-DR15+ patients. Unlike native MBP, citMBP induced differentiation into Th17 cells in cultures from HDs, while neither form of MBP induced Th17-cell differentiation in cultures from patients with MS. These data suggest a role for citrullination in the breach of tolerance to MBP in healthy individuals and in maintenance of the autoimmune response to MBP in patients with MS.

Cerebrospinal fluid soluble CD27 is associated with CD8+ T cells, B cells and biomarkers of B cell activity in relapsing-remitting multiple sclerosis.

Cerebrospinal fluid (CSF) soluble CD27 (sCD27) is a sensitive biomarker of intrathecal inflammation. Although generally considered a biomarker of T cell activation, CSF sCD27 has been shown to correlate with biomarkers of B cell activity in multiple sclerosis. We analyzed CSF from 40 patients with relapsing-remitting multiple sclerosis (RRMS) and nine symptomatic controls using flow cytometry and multiplex electrochemiluminescence immunoassays. CSF sCD27 levels were increased in RRMS and correlated with IgG index, soluble B cell maturation antigen, cell count, B cell frequency and CD8+ T cell frequency. We provide new data indicating that CSF sCD27 is associated with CD8+ T cells and B cells in RRMS.

Intrathecal CD8+CD20+ T Cells in Primary Progressive Multiple Sclerosis.

BACKGROUND AND OBJECTIVE: Despite accumulating evidence of intrathecal inflammation in patients with primary progressive multiple sclerosis (PPMS), immunomodulatory and suppressive treatment strategies have proven unsuccessful. With this study, we investigated the involvement of CD20+ T cells and the effect of dimethyl fumarate on CD20+ T cells in PPMS. METHODS: The main outcomes in this observational, case-control study were flow cytometry assessments of blood and CSF CD20+ T cells and ELISA measurements of myelin basic protein and neurofilament light chain in untreated patients with PPMS and patients treated for 48 weeks with dimethyl fumarate or placebo. MRI measures included new and enlarging T2-weighted lesions over 48 weeks and lesion, normal-appearing white matter, cortical, and thalamic volume. RESULTS: Assessing CD20+ T cells in patients with PPMS and controls showed an increased percentage of CD20+ T cells in the blood of untreated patients and a strong enrichment in the CSF. In addition, a higher frequency of CD8+CD20+ T cells in the CSF correlated with a higher concentration of myelin basic protein and T2-weighted lesion volume and with a lower normal-appearing white matter and thalamus volume. Furthermore, CD8+CD20+ T cells were associated with the development of new T2 lesions. After 48 weeks of treatment with dimethyl fumarate, total T cells in CSF were reduced; however, CD20+ T cells were unaffected. DISCUSSION: This study shows an association between intrathecal CD8+CD20+ T cells, white matter injury, and thalamic atrophy in PPMS, suggesting a role of CD8+CD20+ T cells in the immunopathogenesis of PPMS. The results also suggest that limited efficacy of dimethyl fumarate in PPMS may, at least partly, be a consequence of failure to suppress CD8+CD20+ T cells in CSF.

Cladribine Effects on T and B Cells and T Cell Reactivity in Multiple Sclerosis.

OBJECTIVE: Cladribine tablet therapy is an efficacious treatment for multiple sclerosis (MS), however, its mechanism of action on T and B cell subsets remains unclear. The purpose of this study was to investigate the treatment effects of cladribine on the peripheral pool of T and B cells subsets and reactivity toward central nervous system (CNS) antigens. METHODS: In this cross-sectional exploratory study, frequencies and absolute counts of peripheral T and B cell subsets and B cell cytokine production from untreated patients with relapsing-remitting MS (RRMS) and patients treated with cladribine for 1 year were measured using flow cytometry. Autoreactivity was assessed using a FluoroSpot assay. RESULTS: We found that 1 year after initiation of cladribine treatment, a lower number of CD4+ T cells was persisting whereas CD19+ B cell counts were normalized compared to untreated patients with RRMS. Follicular helper T cells and their effecter subsets producing cytokines exerting distinct B cell helper activity were lower and, additionally, the peripheral B cell pool was skewed toward a naïve and anti-inflammatory phenotype. Finally, reactivity to the recently identified CNS-enriched autoantigen RAS guanyl-releasing protein 2 (RASGRP2), but not to myelin basic protein and myelin oligodendrocyte glycoprotein, was lower in cladribine-treated patients. INTERPRETATION: Together, these investigations on T and B cell subsets suggest that cladribine treatment impairs the B-T cell crosstalk and reduces their ability to mediate pathogenic effector functions. This may result in specific reduction of autoreactivity to RASGRP2 which is expressed in B cells and brain tissue. ANN NEUROL 2023;94:518-530.

Relationship between cerebrospinal fluid biomarkers of inflammation and tissue damage in primary progressive multiple sclerosis.

BACKGROUND AND OBJECTIVES: It is unclear to what extent intrathecal inflammation contributes to the pathogenesis in primary progressive multiple sclerosis (PPMS). We conducted an exploratory study to investigate the degree of intrathecal inflammation and its association with biomarkers of disease activity and severity in patients with PPMS. METHODS: We included patients with PPMS who participated in a randomized controlled trial conducted at the Danish Multiple Sclerosis Center, patients with relapsing-remitting multiple sclerosis (RRMS) and healthy controls. We analyzed concentrations of a panel of cytokines in CSF using electrochemiluminescence assays. We then explored the relationship between cytokines found in increased CSF concentrations in patients with PPMS (compared with healthy controls) with CSF concentrations of neurofilament light chain (NFL) and myelin basic protein (MBP), IgG-index, and magnetic resonance imaging (MRI) metrics (volume, magnetization transfer ratio and diffusion tensor imaging) from lesions, normal-appearing white matter, and cortical grey matter. RESULTS: We included 59 patients with PPMS, 40 patients with RRMS, and 21 healthy controls. In patients with PPMS, CSF concentrations of CC chemokine ligand 3 (CCL-3), CXC chemokine ligand 8 (CXCL-8), CXCL-10, interleukin (IL)-10, IL-15, and vascular endothelial growth factor (VEGF)-A were increased compared with healthy controls and comparable with CSF concentrations in patients with RRMS. In addition, patients with PPMS had increased CSF concentrations of IL-12p40, IL-17A, tumor necrosis factor (TNF)-α, and lymphotoxin (LT)-α compared with healthy controls, but concentrations of these cytokines were even higher in patients with RRMS. For the remaining seven cytokines (CCL22, interferon-γ, IL-5, IL-7, IL-16, IL-22, IL-27), we found no difference between patients with PPMS and healthy controls. CSF concentrations of NFL and MBP correlated weakly with concentrations of IL-15, while the remaining proinflammatory cytokines were not associated with CSF concentrations of NFL or MBP. The IgG-index correlated with four cytokines (IL-10, IL-12p40, TNF-α, and LT-α). We did not observe any significant associations between MRI metrics and CSF biomarkers of inflammation. DISCUSSION: In this exploratory study, we found few and weak associations between intrathecal inflammation and the extent of neuroaxonal damage and demyelination, and no associations between intrathecal inflammation and MRI metrics, in patients with PPMS. Our findings suggest that, for patients with PPMS, these measures of intrathecal inflammation are not associated with the extent of neuroaxonal injury, demyelination, and disease severity, and these processes may therefore have less relevance in PPMS than in relapsing forms of MS.

Increased Intrathecal Activity of Follicular Helper T Cells in Patients With Relapsing-Remitting Multiple Sclerosis.

BACKGROUND AND OBJECTIVES: Follicular helper T (Tfh) cells play a critical role in protective immunity helping B cells produce antibodies against foreign pathogens and are likely implicated in the pathogenesis of various autoimmune diseases. The purpose of this study was to investigate the role of Tfh cells in the pathogenesis of multiple sclerosis (MS). METHODS: Using flow cytometry, we investigated phenotype, prevalence, and function of Tfh cells in blood and CSF from controls and patients with relapsing-remitting MS (RRMS) and primary progressive MS (PPMS). In addition, an in vitro blood-brain barrier coculture assay of primary human astrocytes and brain microvascular endothelial cells grown in a Boyden chamber was used to assess the migratory capacity of peripheral Tfh cells. RESULTS: This study identified 2 phenotypically and functionally distinct Tfh cell populations: CD25- Tfh cells (Tfh1-like) and CD25int Tfh cells (Tfh17-like). Whereas minor differences in Tfh cell populations were found in blood between patients with MS and controls, we observed an increased frequency of CD25- Tfh cells in CSF of patients with RRMS and PPMS and CD25int Tfh cells in patients with RRMS, compared with controls. Increasing frequencies of CSF CD25- Tfh cells and the CD25- Tfh/Tfr ratio scaled with increasing IgG index in patients with RRMS. Despite an increased prevalence of intrathecal Tfh cells in patients with MS, no difference in the migratory capacity of circulating Tfh cells was observed between controls and patients with MS. Instead, CSF concentrations of CXCL13 scaled with total counts of Tfh and Tfr cell subsets in the CSF. DISCUSSION: Our study indicates substantial changes in intrathecal Tfh dynamics, particularly in patients with RRMS, and suggests that the intrathecal inflammatory environment in patients with RRMS promotes recruitment of peripheral Tfh cells rather than the Tfh cells having an increased capacity to migrate to CNS.

Ofatumumab Modulates Inflammatory T Cell Responses and Migratory Potential in Patients With Multiple Sclerosis.

BACKGROUND AND OBJECTIVES: The anti-CD20 antibody ofatumumab is an efficacious therapy for multiple sclerosis (MS) through depletion of B cells. The purpose of this study was to examine the derivative effects of B cell depletion on the peripheral immune system and a direct treatment effect on T cells expressing CD20. METHODS: Frequency and absolute numbers of peripheral leukocytes of treatment-naive patients with relapsing-remitting MS (RRMS) and patients treated with ofatumumab for a mean of 482 days were assessed in this observational study by flow cytometry. In addition, effector function and CNS migration of T cells using a human in vitro blood-brain barrier (BBB) assay were analyzed. RESULTS: This study showed that ofatumumab treatment of patients with RRMS increased the control of effector T cells and decreased T cell autoreactivity. It also showed that ofatumumab reduced the level of peripheral CD20+ T cells and that the observed decrease in CNS-migratory capacity of T cells was caused by the depletion of CD20+ T cells. Finally, our study pointed out a bias in the measurement of CD20+ cells due to a steric hindrance between the treatment antibody and the flow cytometry antibody. DISCUSSION: The substantial ofatumumab-induced alteration in the T cell compartment including a severely decreased CNS-migratory capacity of T cells could partly be attributed to the depletion of CD20+ T cells. Therefore, we propose that depletion of CD20+ T cells contributes to the positive treatment effect of ofatumumab and suggests that ofatumumab therapy should be considered a B cell and CD20+ T cell depletion therapy. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that compared with treatment-naive patients, ofatumumab treatment of patients with RRMS decreases peripheral CD20+ T cells, increases effector T cell control, and decreases T cell autoreactivity.

Peripheral helper T cells in the pathogenesis of multiple sclerosis.

BACKGROUND: Peripheral helper T cells (Tph) are likely implicated in the pathogenesis of various inflammatory diseases. Tph cells share functions with follicular helper T cells, including plasma cell differentiation and antibody production. OBJECTIVE AND METHODS: To investigate a possible role of Tph cells in the pathogenesis of multiple sclerosis (MS), we used flow cytometry to analyze the function, phenotype, and central nervous system (CNS)-recruitment of Tph cells in the blood and cerebrospinal fluid (CSF) from controls and patients with relapsing-remitting (RR) and primary progressive (PP) MS. RESULT: This study identified two functionally distinct Tph cell populations and a regulatory counterpart, Tpr cells. No differences in blood frequencies, cytokine production, or potential to interact with B cells were found between controls and patients with MS. Along with an equal CNS-migration potential, we found both Tph cell populations enriched in the CSF; and surprisingly, an increased frequency of intrathecal Tph cells in the control group compared to patients with MS. CONCLUSION: Altogether, we did not find an increased frequency of CSF Tph cells in patients with RRMS or PPMS. Our findings indicate that rather than being involved in MS pathogenesis, Tph cells may be implicated in normal CNS immunosurveillance.

Assessment of commonly used methods to determine myelin-reactivity of T cells in multiple sclerosis.

Many studies have analyzed myelin-reactivity of T cells in multiple sclerosis (MS); however, with conflicting results. In this study we compare methods to determine myelin reactivity of T cells and aim to delineate the cause of inconsistency in the literature. Challenging T cells with myelin antigens we found a significant increase in antigen-reactivity of T cells from patients with MS using an ELISpot-assay, in contrast to a CFSE-dilution assay. Comparing the two assays showed that the myelin-reactive T cells detected in the ELISpot-assay originated primarily from effector memory T cells in contrast to the myelin-reactive T cells of the CFSE-assay representing a population of both naïve, central memory and effector memory T cells. This diversity in T cell populations activated in the two assays likely contribute to the discrepancy found in the literature and encourages thorough considerations when choosing an assay to determine antigen-specificity of T cells in future studies.

IL2RA Methylation and Gene Expression in Relation to the Multiple Sclerosis-Associated Gene Variant rs2104286 and Soluble IL-2Rα in CD8+ T Cells.

CD8+ T cells are involved in the pathogenesis of multiple sclerosis (MS). The interleukin-2 receptor α (IL-2Rα) is important for CD8+ T cell function, and single nucleotide polymorphisms (SNPs) in the IL2RA gene encoding IL-2Rα increase the risk of MS. Therefore, in isolated CD8+ T cells we investigated IL2RA gene methylation and gene expression in relation to the MS-associated IL2RA SNP rs2104286 and soluble IL-2Rα (sIL-2Rα). We have identified allele specific methylation of the CpG-site located in intron 1 that is perturbed by the rs2104286 SNP in CD8+ T cells from genotype-selected healthy subjects (HS). However, methylation of selected CpG-sites in the promotor or 5'UTR region of the IL2RA gene was neither associated with the rs2104286 SNP nor significantly correlated with IL2RA gene expression in HS. In CD8+ T cells from HS, we explored expression of immune relevant genes but observed only few associations with the rs2104286 SNP. However, we found that sIL-2Rα correlated negatively with expression of 55 immune relevant genes, including the IL-7 receptor gene, with Spearman's rho between -0.49 and -0.32. Additionally, in HS by use of flow cytometry we observed that the IL-7 receptor on naïve CD8+ T cells correlated negatively with sIL-2Rα and was downregulated in carriers of the rs2104286 MS-associated risk genotype. Collectively, our study of resting CD8+ T cells indicates that the rs2104286 SNP has a minor effect and sIL-2Rα may negatively regulate the CD8+ T cell response.

Dimethyl Fumarate Treatment in Patients With Primary Progressive Multiple Sclerosis: A Randomized, Controlled Trial.

BACKGROUND AND OBJECTIVE: To study whether dimethyl fumarate is superior to placebo in decreasing CSF concentrations of neurofilament light chain (NFL) in patients with primary progressive MS (PPMS). METHODS: In the double-blind, placebo-controlled phase 2 study dimethyl FUMArate treatment in Progressive Multiple Sclerosis (FUMAPMS), patients with PPMS were randomly assigned to treatment with 240 mg dimethyl fumarate or placebo in a 1:1 ratio for 48 weeks. The primary endpoint was change in concentration of NFL in the CSF. Secondary endpoints included other CSF biomarkers and clinical and MRI measures. Efficacy was evaluated for the full data set by multiple imputations to account for missing data. Safety was assessed for the full data set. RESULTS: Fifty-four patients (mean age 54.9 years [SD 6.1], median Expanded Disability Status Scale 4.0 [nterquartile range 4.0-6.0], disease duration 14.1 [SD 9.4], and 21 [39%] female) were randomized to either placebo (n = 27) or dimethyl fumarate (n = 27) therapy. At screening CSF concentrations, adjusted for age and sex, of NFL, myelin basic protein (MBP), soluble CD27, chitinase 3-like 1, and B-cell maturation antigen were higher than in a group of symptomatic controls. Twenty-six patients (96%) in the dimethyl fumarate group and 24 patients (89%) in the placebo group completed the randomized phase. Mean change in CSF concentrations of NFL did not differ between groups (mean difference 99 ng/L; 95% CI -292 to 491 ng/L). MBP in CSF decreased in the treatment group (-182 ng/L, 95% CI -323 to -41 ng/L compared with placebo). The difference observed in the multiple imputation data set was not significant in a per protocol analysis. This was nominally significant in the multiple imputation data set but not in the per protocol analysis This was not found in the per protocol analysis Other secondary and tertiary outcomes were not affected. Various infections, lymphopenia, flushing, and gastrointestinal side effects were more frequent in the dimethyl fumarate group. Serious adverse events were similar between groups. DISCUSSION: Dimethyl fumarate treatment for 48 weeks had no effect on any of the investigated efficacy measures in patients with PPMS. We did not observe adverse events not anticipated for dimethyl fumarate treatment. TRIAL REGISTRATION INFORMATION: Clinicaltrials.gov identifier NCT02959658. CLASSIFICATION OF EVIDENCE: This study provides Class I evidence that for patients with PPMS, dimethyl fumarate treatment has no effect on CSF NFL levels compared with placebo treatment.

Natalizumab differentially affects plasmablasts and B cells in multiple sclerosis.

BACKGROUND: Natalizumab treatment increases the frequencies of B cells in blood but reduces IgG in blood and CSF. Plasmablasts are important in the production of IgG, and the development of plasmablasts is CD49d dependent. OBJECTIVE: We hypothesized that natalizumab treatment affects the development of plasmablasts. METHODS: We retrospectively analyzed frequencies and absolute counts of B cell subsets by flow cytometry from a longitudinal cohort of 9 progressive multiple sclerosis (MS) patients treated with natalizumab for 60 weeks, and a cross-sectional relapsing-remitting MS (RRMS) cohort with 17 untreated and 37 treated with natalizumab (17 stable and 20 unstable patients with relapse activity). Additionally, CD49d expression on B cell subsets was examined in 10 healthy controls, and blood and cerebrospinal fluid (CSF) frequencies of B cell subsets were quantified in untreated and natalizumab treated RRMS patients. RESULTS: In progressive MS, levels of IgG decreased in plasma (p<0.001) from baseline to 60 weeks follow-up. In the progressive MS and RRMS cohorts we observed that natalizumab treatment significantly increased the frequency of B cells (p=0.004; p<0.0001) and several B cell subsets, most pronounced for memory B cell subsets (p=0.0001; p<0.0001), while there was a decrease in plasmablast frequency (p=0.008; p=0.008). In both progressive MS and RRMS the absolute cell counts of B cells increased (p=0.004; p<0.001), which was explained by a significant increase in all subsets, except for plasmablasts. Furthermore, we found decreased memory B cell counts in unstable compared to stable natalizumab-treated patients (p=0.02). The expression of CD49d was higher on plasmablasts compared to other B cell subsets (p<0.0001). In CSF, plasmablasts could not be detected in patients treated with natalizumab, in contrast to an increased frequency in untreated RRMS patients. CONCLUSION: We confirm previous studies showing that natalizumab increases circulating number of B cells, particularly memory cells, concomitant with a decrease in plasma IgG concentrations. Moreover, we demonstrate in two separate cohorts that natalizumab treatment markedly decreases frequencies of plasmablasts while the absolute number is stable. Additionally, plasmablasts have high expression of CD49d, and plasmablasts could not be detected in the CSF of natalizumab-treated patients. Finally, memory B cells were found to be reduced in unstable natalizumab-treated patients, which could possibly indicate increased recruitment to the CNS.

Multiplex assessment of cerebrospinal fluid biomarkers in multiple sclerosis.

BACKGROUND: Several roles for biomarkers in multiple sclerosis (MS) exist, including aiding in the diagnosis of MS, predicting disease activity or progression, and defining individuals who may be responsive to specific treatments. Cerebrospinal fluid (CSF) concentrations of soluble B cell maturation antigen (sBCMA) and soluble CD27 (sCD27) have been shown to be sensitive biomarkers of inflammation in MS and are thought to reflect B and T cell activity, respectively. Furthermore, chitinase 3-like 1 (CHI3L1) and soluble CD14 (sCD14) have been suggested as measures of innate immune cell activity in MS. In this study we sought to validate measurements of these CSF biomarkers of inflammation using multiplex bead-based immunoassays. METHODS: By using commercially available multiplex bead-based assays, concentrations of sBCMA, sCD27, sCD14 and CHI3L1 were determined in CSF from 22 patients with either untreated clinically isolated syndromes (CIS) or relapsing-remitting MS (RRMS), 13 patients with RRMS treated with either natalizumab or alemtuzumab, and 35 symptomatic controls (SC). RESULTS: Increased CSF concentrations of sBCMA, sCD27 and CHI3L1 were observed in untreated MS patients compared to symptomatic controls (all p < 0.001). Concentrations of sBCMA (p = 0.02) and sCD27 (p = 0.0003) were higher in treated MS patients than in SC, and levels of sBCMA (p = 0.02) and sCD27 (p = 0.01) were even higher in untreated compared to treated patients. sCD14 levels did not differ between the groups. Levels of sBCMA and sCD27 correlated strongly with each other (Spearman's rho: 0.98, p < 0.0001) as well as with the IgG index (Spearman's rho: 0.91, p < 0.0001 and 0.90, p < 0.0001, respectively). ROC curve analysis showed a high discriminatory potential for sBCMA and sCD27 with areas under the curve of 0.88 and 0.93, respectively. CONCLUSION: We confirm reports of elevated concentrations of sBCMA, sCD27 and CHI3L1 in CSF from untreated MS patients compared to SC. sBCMA and sCD27 levels were elevated in both treated and untreated MS patients compared to SC, but highest in untreated patients. Finally, CSF concentrations of sBCMA, sCD27 and the IgG index correlated strongly, suggesting that the cellular source of sCD27 and sBCMA includes memory B cells, plasmablasts and plasma cells.

MAIT cell subtypes in multiple sclerosis.

In patients with multiple sclerosis (MS) and healthy controls (HC) we studied circulating MAIT cells and MAIT cell subtypes expressing CXCR3 and CCR6 by flow cytometry. Absolute numbers of MAIT cells and specifically Tc17-like MAIT cells were lower in patients with primary progressive MS (PPMS) than in controls. Low numbers of Tc17-like MAIT cells were associated with smoking and high concentrations of myelin basic protein in the cerebrospinal fluid. Treatment with alemtuzumab and dimethyl fumarate decreased MAIT cell frequencies. Altogether, we have identified specific MAIT cell subtypes related to PPMS, smoking and demyelination, and MAIT cell effects of MS therapies.

Dimethyl fumarate therapy reduces memory T cells and the CNS migration potential in patients with multiple sclerosis.

BACKGROUND: Dimethyl fumarate (DMF) is a disease-modifying therapy for patients with relapsing-remitting multiple sclerosis (RRMS). T cells are major contributors to the pathogenesis of RRMS, where they regulate the pathogenic immune response and participate in CNS lesion development. OBJECTIVES: In this study we evaluate the therapeutic effects of DMF on T cell subpopulations, their CNS migration potential and effector functions. METHODS: Blood and CSF from untreated and DMF-treated patients with RRMS and healthy donors were analyzed by flow cytometry. RESULTS: DMF reduced the prevalence of circulating proinflammatory CD4+ and CD8+ memory T cells, whereas regulatory T cells were unaffected. Furthermore, DMF reduced the frequency of CD4+ T cells expressing CNS-homing markers. In coherence, we found a reduced recruitment of CD4+ but not CD8+ T cells to CSF. We also found that monomethyl fumarate dampened T cell proliferation and reduced the frequency of TNF-α, IL-17 and IFN-γ producing T cells. CONCLUSION: DMF influences the balance between proinflammatory and regulatory T cells, presumably favoring a less proinflammatory environment. DMF also reduces the CNS migratory potential of CD4+ T cells whereas CD8+ T cells are less affected. Altogether, our study suggests an anti-inflammatory effect of DMF mainly on the CD4+ T cell compartment.

Early Intrathecal T Helper 17.1 Cell Activity in Huntington Disease.

OBJECTIVE: Huntington disease (HD) is an autosomal dominantly inherited neurodegenerative disorder caused by a CAG repeat expansion in the huntingtin (HTT) gene. No disease-modifying therapy exists for the treatment of patients with HD. The purpose of this study was therefore to investigate early disease mechanisms that potentially could be used as a target therapeutically. METHODS: Lymphocyte activity in cerebrospinal fluid (CSF) from 4 cohorts of HTT gene expansion carriers (n = 121 in total) and controls was analyzed by techniques based on flow cytometry and enzyme-linked immunosorbent assays. RESULTS: The data of this study provide evidence of immune abnormalities before motor onset of disease. In CSF of HTT gene expansion carriers, we found increased levels of proinflammatory cytokines, including IL-17, and increased consumption of the lymphocyte growth factor IL-7 before motor onset of HD. In concordance, we observed an increased prevalence of IL-17-producing Th17.1 cells in the CSF of HTT gene expansion carriers, predominantly in pre-motor manifest individuals. The frequency of intrathecal Th17.1 cells correlated negatively with progression of HD and the level of neurodegeneration, suggesting a role of Th17.1 cells in the early disease stage. We also observed a skewing in the balance between proinflammatory and regulatory T cells potentially favoring a proinflammatory intrathecal environment in HTT gene expansion carriers. INTERPRETATION: These data suggest that Th17.1 cells are implicated in the earliest pathogenic phases of HD and suggest that treatment to dampen T -cell-driven inflammation before motor onset might be of benefit in HTT gene expansion carriers. ANN NEUROL 2020;87:246-255.