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Background: The measurement of neurofilament light (NFL) in blood samples has been established as a sensitive measure of neuroaxonal damage in a wide range of diseases in the peripheral and central nervous system, including multiple sclerosis (MS). Previous studies have identified confounding factors that may influence the serum concentration of NFL., Aim: We aimed at investigating the relationship between known confounders (age, body mass index, blood volume) and risk factors for MS (smoking and human leukocyte antigen (HLA)) on serum concentrations of NFL in control subjects. In addition, we compared different methods for correction for confounders when applied to newly diagnosed patients with MS., Methods: We measured serum concentrations of NFL by single molecule array analysis in 1.101 control subjects without neurological disease from 4 different cohorts (including 906 healthy blood donors) and 72 patients with newly diagnosed relapsing-remitting MS. A questionnaire on smoking habits was distributed to the 906 healthy blood donors, and the HLA risk alleles HLA-DRB1*15:01 and HLA-A*02:01 were genotyped by TaqMan allelic-discrimination PCR analysis in these subjects., Results: We confirmed that serum concentrations of NFL increase with age, but we also found that sample storage conditions for the different cohorts of control subjects had a substantial effect. Prolonged storage time and storage at -20° were independently associated with lower serum concentrations of NFL than shorter storage time and storage at -80° In samples from the large cohort of blood donors, we confirmed an association between high BMI and high blood volume with lower serum concentrations of NFL and found that this association was marginally stronger for BMI than for blood volume. We found no association between smoking and HLA risk factors for MS with serum concentrations of NFL in the blood donor cohort. Finally, we found that a simple method for correcting for the effect of age on NFL performed as well as Z-scores, which consider the effect of both age and BMI. This was shown when discriminating between patients with MS and control subjects and between MS patients with and without Gd-enhancing MRI lesions., Conclusions: We confirm an association between serum concentrations of NFL, age, and BMI, but we also find that it may often be sufficient to correct for the effect of age alone. The effect of BMI should, however, be considered along with the effect of other confounding factors, including various comorbidities., Competing Interests: Declaration of competing interest Helle Bach Søndergaard, Anna Olsson, Cecilie Ammitzbøll, Lise Wegner Thørner, Erik Sørensen, Marie Krogh Nielsen, Josefine Britze, Signe Modvig, Poul Erik Hyldgaard Jensen, Torben Lykke Sørensen, Annette Bang Oturai have nothing to declare. Stefan Gustavsen has received support for congress participation from Merck and Sanofi. Finn Sellebjerg has served on scientific advisory boards for, served as consultant for, received support for congress participation or received speaker honoraria from Alexion, Biogen, Bristol Myers Squibb, Lundbeck, Merck, Novartis, Roche and Sanofi Genzyme. His laboratory has received research support from Biogen, Merck, Novartis, Roche and Sanofi Genzyme., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

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., (Copyright © 2022 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.)

Soluble interleukin-2 (IL-2) receptor α (sIL-2Rα) antagonizes IL-2 signaling and is involved in the pathogenesis of several immune-mediated diseases including multiple sclerosis (MS). The level of sIL-2Rα is affected by the MS-associated single nucleotide polymorphism (SNP) rs2104286. By use of ELISA and electrochemiluminescence, we investigated if 26 biomarkers of systemic inflammation were associated with sIL-2Rα and rs2104286 in cohorts of healthy subjects and MS patients in serum and heparin plasma. We found that sIL-2Rα significantly correlated with the level of tumor necrosis factor-α (TNFα) (r = 0.391, p = 0.002) in healthy subjects and the association was validated in a separate cohort. Additional, in healthy subjects we confirmed a previous report indicating that C-reactive protein (CRP) correlates with sIL-2Rα (r = 0.278, p = 0.034). None of the biomarkers of systemic inflammation were significantly associated with sIL-2Rα in MS patients. Furthermore, the MS-associated SNP rs2104286 was not significantly associated with any of the biomarkers of systemic inflammation in neither healthy subjects nor MS patients. We conclude that sIL-2Rα is associated with TNFα and CRP in healthy subjects. However, further research is required to confirm the use of sIL-2Rα as biomarker of systemic inflammation as well as to assess the mechanism underlying the observed correlation between levels of sIL-2Rα and TNFα., (Copyright © 2021. Published by Elsevier B.V.)

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., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Background and Objective: The aim of this study was to determine whether natural killer T (NKT) cells, including invariant (i) NKT cells, have clinical value in preventing the progression of multiple sclerosis (MS) by examining the mechanisms by which a distinct self-peptide induces a novel, protective invariant natural killer T cell (iNKT cell) subset., Methods: We performed a transcriptomic and functional analysis of iNKT cells that were reactive to a human collagen type II self-peptide, hCII707-721, measuring differentially induced genes, cytokines, and suppressive capacity., Results: We report the first transcriptomic profile of human conventional vs novel hCII707-721-reactive iNKT cells. We determined that hCII707-721 induces protective iNKT cells that are found in the blood of healthy individuals but not progressive patients with MS (PMS). By transcriptomic analysis, we observed that hCII707-721 promotes their development and proliferation, favoring the splicing of full-length AKT serine/threonine kinase 1 (AKT1) and effector function of this unique lineage by upregulating tumor necrosis factor (TNF)-related genes. Furthermore, hCII707-721-reactive iNKT cells did not upregulate interferon (IFN)-γ, interleukin (IL)-4, IL-10, IL-13, or IL-17 by RNA-seq or at the protein level, unlike the response to the glycolipid alpha-galactosylceramide. hCII707-721-reactive iNKT cells increased TNFα only at the protein level and suppressed autologous-activated T cells through FAS-FAS ligand (FAS-FASL) and TNFα-TNF receptor I signaling but not TNF receptor II., Discussion: Based on their immunomodulatory properties, NKT cells have a potential value in the treatment of autoimmune diseases, such as MS. These significant findings suggest that endogenous peptide ligands can be used to expand iNKT cells, without causing a cytokine storm, constituting a potential immunotherapy for autoimmune conditions, including PMS., (Copyright © 2021 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.)

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., (Copyright © 2021. Published by Elsevier B.V.)

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., (Copyright © 2019. Published by Elsevier B.V.)

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., (© 2019 American Neurological Association.)

Perfluorinated alkylated substances (PFASs) have immunomodulatory effects but the impact on multiple sclerosis (MS) and cellular immune functions is only sparsely described. In the present study, we found lower concentrations of the long chain PFAS perfluorooctane sulfonic acid (PFOS) in MS than in healthy controls (HC). In HC, we did not detect associations between PFOS concentrations and immune phenotypes. Analyzing the impact of known MS risk factors on cellular immune functions, we found that smoking and Epstein-Barr nuclear antigen 1 antibodies were associated with distinct circulating immune cell changes. In summary, current background PFAS exposure is not an important risk factor for MS., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Smoking is a risk factor for the development and progression of multiple sclerosis (MS); however, the pathogenic effects of smoking are poorly understood. We studied the smoking-associated chemokine receptor-like molecule GPR15 in relation to relapsing-remitting MS (RRMS). Using microarray analyses and qPCR we found elevated GPR15 in blood cells from smokers, and increased GPR15 expression in RRMS. By flow cytometry we detected increased frequencies of GPR15 expressing T and B cells in smokers, but no difference between patients with RRMS and healthy controls. However, after cell culture with the autoantigens myelin basic protein (MBP) and myelin oligodendrocyte glycoprotein, frequencies of MBP-reactive and non-proliferating GPR15 + CD4 + T cells were increased in patients with RRMS compared with healthy controls. GPR15 + CD4 + T cells produced IL-17 and were enriched in the cerebrospinal fluid (CSF). Furthermore, in the CSF of patients with RRMS, GPR15 + T cells were associated with CCR6 + CXCR3 + /CCR6 - CXCR3 + phenotypes and correlated positively with concentrations of the newly identified GPR15-ligand (GPR15L), myelin degradation and disability. In conclusion, we have identified a proinflammatory cell type linking smoking with pathogenic immune cell functions in RRMS., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

With the discovery that the highly effective anti-CD20 antibody therapies developed to deplete CD20+ B cells deplete CD20+ T cells equally well, a great interest in the biological properties of CD20+ T cells has emerged. In this study we show that CD20+ T cells have a proinflammatory Th1/Tc1 phenotype with a high proliferative capacity to CNS antigens. We also found that the percentage of CD20+ T cells is increased in the blood of patients with multiple sclerosis and are enriched in the CSF of the patients. Furthermore, we found a positive correlation between CD20+ T cells in the CSF and multiple sclerosis disease severity and see that regulation of CD20+ T cells likely contributes to the positive treatment effect of the multiple sclerosis treatment alemtuzumab. These data represent an important contribution to the understanding of the nature of CD20+ T cells and strongly suggests a role of CD20+ T cells in the pathogenesis of multiple sclerosis.

Background: Patients with progressive multiple sclerosis (MS) often have cognitive impairment in addition to physical impairment. The burden of cognitive and physical impairment progresses over time, and may be major determinants of quality of life. The aim of this study was to assess to which degree quality of life correlates with physical and cognitive function in progressive MS., Methods: This is a retrospective study of 52 patients with primary progressive ( N  = 18) and secondary progressive MS ( N  = 34). Physical disability was assessed using the Expanded Disability Status Scale, Timed 25 Foot Walk (T25FW) test and 9-Hole Peg Test (9HPT). Cognitive function was assessed using Symbol Digit Modalities Test (SDMT), Paced Auditory Serial Addition Test, and Trail Making Test B (TRAIL-B). In addition, quality of life was assessed by the Short Form 36 (SF-36) questionnaire., Results: Only measures of cognitive function correlated with the overall SF-36 quality of life score and the Mental Component Summary score from the SF-36. The only physical measure that correlated with a measure of quality of life was T25FW test, which correlated with the Physical Component Summary from the SF-36. We found no other significant correlations between the measures of cognitive function and the overall physical measures but interestingly, we found a possible relationship between the 9HPT score for the nondominant hand and the SDMT and TRAIL-B., Conclusion: Our findings support inclusion of measures of cognitive function in the assessment of patients with progressive MS as these correlated closer with quality of life than measures of physical impairment.

Background: It is unknown whether disease activity according to consensus criteria (magnetic resonance imaging activity or clinical relapses) associate with cerebrospinal fluid (CSF) changes in progressive multiple sclerosis (MS)., Objective: To compare CSF biomarkers in active and inactive progressive MS according to consensus criteria., Methods: Neurofilament light chain (NFL), myelin basic protein (MBP), IgG-index, chitinase-3-like-1 (CHI3L1), matrix metalloproteinase-9 (MMP-9), chemokine CXCL13, terminal complement complex, leukocyte counts and nitric oxide metabolites were measured in primary ( n = 26) and secondary progressive MS ( n = 26) and healthy controls ( n = 24)., Results: Progressive MS patients had higher CSF cell counts, IgG-index, CHI3L1, MMP-9, CXCL13, NFL and MBP concentrations. Active patients were younger and had higher NFL, CXCL13 and MMP-9 concentrations than inactive patients. Patients with active disease according to consensus criteria or detectable CXCL13 or MMP-9 in CSF were defined as having combined active progressive MS. These patients had increased CSF cell counts, IgG-index and MBP, NFL and CHI3L1 concentrations. Combined inactive patients only had increased IgG-index and MBP concentrations., Conclusion: Patients with combined active progressive MS show evidence of inflammation, demyelination and neuronal/axonal damage, whereas the remaining patients mainly show evidence of active demyelination. This challenges the idea that neurodegeneration independent of inflammation is crucial in disease progression.

Upon chronic cigarette smoke exposure, inhaled antigens and irritants cause altered lung immune homeostasis. Circulating immune cells are affected, and smoking is associated with an increased risk of developing various disorders, including multiple sclerosis (MS). This study was conducted to determine the impact of smoking on circulating immune cell subsets. Furthermore, we determined whether any smoking-associated changes were related to MS. With the use of flow cytometry, CFSE assays, and ELISpot assays, we analyzed circulating immune cell phenotypes and quantified antigen-induced proliferation and cytokine secretion in smokers and nonsmokers in a cohort of 100 healthy individuals (HI). In addition, we analyzed immune cell subsets associated with smoking in 2 independent cohorts of patients with MS. In HI smokers compared with nonsmokers, we found increased blood cell counts of granulocytes, monocytes, and lymphocytes. These cells were not more proinflammatory, autoreactive, or EBV reactive compared with cells from nonsmokers. Phenotypic differences were seen in plasmacytoid dendritic cells (pDCs) and CD8 + T cells as higher percentages of ICOS ligand (ICOSL) + pDCs and lower percentages of CD26 hi CD161 hi CD8 + T cells and CCR6 + CD8 + T cells in smokers compared with nonsmokers. In supplemental analyses, we showed that CD26 hi CD161 hi CD8 + T cells were mainly mucosal-associated invariant T cells (MAITs). Comparable frequencies of ICOSL + pDCs, CCR6 + CD8 + T cells, and CD26 hi CD161 hi CD8 + T cells were found between HI and MS patients who were nonsmokers. Our findings suggest general proinflammatory effects from smoking combined with skewing of specific cell populations in HI and MS patients. The function of these cell populations needs further investigation., (© Society for Leukocyte Biology.)

Objective: To investigate CSF biomarkers of neuroinflammation and neurodegeneration in Huntington disease (HD) gene-expansion carriers compared to controls and to investigate these biomarkers in association with clinical HD rating scales and disease burden score., Methods: We collected CSF from 32 premanifest and 48 manifest HD gene-expansion carriers and 24 gene-expansion negative at-risk controls. We examined biomarkers of neuroinflammation (matrix metalloproteinase 9, C-X-C motif chemokine 13, terminal complement complex, chitinase-3-like-protein 1 [CHI3L1], and osteopontin [OPN]) and neurodegeneration (microtubule-associated protein tau, neurofilament light polypeptide [NFL], and myelin basic protein [MBP]). The study was approved by the Ethics Committee of the Capital Region of Denmark (H2-2011-085) and written informed consent was obtained from each participant before enrollment., Results: NFL was the only biomarker that increased in premanifest stages and no evidence of early involvement of neuroinflammation in HD was found. However, we found that the biomarkers for neurodegeneration, MBP and tau, increased during the disease course in manifest HD gene-expansion carriers and were associated with an increase of the neuroinflammation biomarkers CHI3L1 and OPN. Tau was also increased in all gene-expansion carriers with psychiatric symptoms compared to gene-expansion carriers without psychiatric symptoms., Conclusions: Neuroinflammation, which seems not to be an early event in our cohort, may be secondary to neurodegeneration in late HD. NFL is a possible disease burden correlate in HD, reflecting neuronal loss even before motor symptom onset, and may be useful as a dynamic biomarker in intervention studies.

Background: There is a large unmet need for treatments for patients with progressive multiple sclerosis (MS). Phase 2 studies with cerebrospinal fluid (CSF) biomarker outcomes may be well suited for the initial evaluation of efficacious treatments., Objective: To evaluate the effect of monthly oral methylprednisolone pulse treatment on intrathecal inflammation in progressive MS., Methods: In this open-label phase 2A study, 15 primary progressive and 15 secondary progressive MS patients received oral methylprednisolone pulse treatment for 60 weeks. Primary outcome was changes in CSF concentrations of osteopontin. Secondary outcomes were other CSF biomarkers of inflammation, axonal damage and demyelination; clinical scores; magnetic resonance imaging measures of disease activity, magnetization transfer ratio (MTR) and diffusion tensor imaging (DTI); motor evoked potentials; and bone density scans., Results: We found no change in the CSF concentration of osteopontin, but we observed significant improvement in clinical scores, MTR, DTI and some secondary CSF outcome measures. Adverse events were well-known side effects to methylprednisolone., Conclusion: Monthly methylprednisolone pulse treatment was safe, but had no effect on the primary outcome. However, improvements in secondary clinical and MRI outcome measures suggest that this treatment regimen may have a beneficial effect in progressive MS., (© The Author(s), 2015.)