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The impact of distinct disease‐modifying therapies (DMTs) on severe acute respiratory syndrome‐coronavirus 2 (SARS‐CoV‐2) vaccination efficacy in patients with multiple sclerosis (MS) is still enigmatic. In this prospective comparative study, we investigated humoral and cellular immune‐responses in patients with MS receiving interferon beta, natalizumab, and ocrelizumab pre‐vaccination and 6 weeks post second SARS‐CoV‐2 vaccination. Healthy individuals and interferon beta‐treated patients generated robust humoral and cellular immune‐responses. Although humoral immune responses were diminished in ocrelizumab‐treated patients, cellular immune‐responses were reduced in natalizumab‐treated patients. Thus, both humoral and cellular immune responses should be closely monitored in patients on DMTs. Whereas patients with a poor cellular immune‐response may benefit from additional vaccination cycles, patients with a diminished humoral immune‐response may benefit from a treatment with SARS‐CoV‐2 antibodies in case of an infection. [ABSTRACT FROM AUTHOR]

Although CSF analysis routinely enables the diagnosis of neurological diseases, it is mainly used for the gross distinction between infectious, autoimmune inflammatory, and degenerative disorders of the CNS. To investigate, whether a multi-dimensional cellular blood and CSF characterization can support the diagnosis of clinically similar neurological diseases, we analysed 546 patients with autoimmune neuroinflammatory, degenerative, or vascular conditions in a cross-sectional retrospective study. By combining feature selection with dimensionality reduction and machine learning approaches we identified pan-disease parameters that were altered across all autoimmune neuroinflammatory CNS diseases and differentiated them from other neurological conditions and inter-autoimmunity classifiers that subdifferentiate variants of CNS-directed autoimmunity. Pan-disease as well as diseases-specific changes formed a continuum, reflecting clinical disease evolution. A validation cohort of 231 independent patients confirmed that combining multiple parameters into composite scores can assist the classification of neurological patients. Overall, we showed that the integrated analysis of blood and CSF parameters improves the differential diagnosis of neurological diseases, thereby facilitating early treatment decisions. [ABSTRACT FROM AUTHOR]

Alemtuzumab is a monoclonal antibody that causes rapid depletion of CD52-expressing immune cells. It has proven to be highly efficacious in active relapsing-remitting multiple sclerosis; however, the high risk of secondary autoimmune disorders has greatly complicated its use. Thus, deeper insight into the pathophysiology of secondary autoimmunity and potential biomarkers is urgently needed. The most critical time points in the decision-making process for alemtuzumab therapy are before or at Month 12, where the ability to identify secondary autoimmunity risk would be instrumental. Therefore, we investigated components of blood and CSF of up to 106 multiple sclerosis patients before and after alemtuzumab treatment focusing on those critical time points. Consistent with previous reports, deep flow cytometric immune-cell profiling (n = 30) demonstrated major effects on adaptive rather than innate immunity, which favoured regulatory immune cell subsets within the repopulation. The longitudinally studied CSF compartment (n = 18) mainly mirrored the immunological effects observed in the periphery. Alemtuzumab-induced changes including increased numbers of naïve CD4+ T cells and B cells as well as a clonal renewal of CD4+ T- and B-cell repertoires were partly reminiscent of haematopoietic stem cell transplantation; in contrast, thymopoiesis was reduced and clonal renewal of T-cell repertoires after alemtuzumab was incomplete. Stratification for secondary autoimmunity did not show clear immununological cellular or proteomic traits or signatures associated with secondary autoimmunity. However, a restricted T-cell repertoire with hyperexpanded T-cell clones at baseline, which persisted and demonstrated further expansion at Month 12 by homeostatic proliferation, identified patients developing secondary autoimmune disorders (n = 7 without secondary autoimmunity versus n = 5 with secondary autoimmunity). Those processes were followed by an expansion of memory B-cell clones irrespective of persistence, which we detected shortly after the diagnosis of secondary autoimmune disease. In conclusion, our data demonstrate that (i) peripheral immunological alterations following alemtuzumab are mirrored by longitudinal changes in the CSF; (ii) incomplete T-cell repertoire renewal and reduced thymopoiesis contribute to a proautoimmune state after alemtuzumab; (iii) proteomics and surface immunological phenotyping do not identify patients at risk for secondary autoimmune disorders; (iv) homeostatic proliferation with disparate dynamics of clonal T- and B-cell expansions are associated with secondary autoimmunity; and (v) hyperexpanded T-cell clones at baseline and Month 12 may be used as a biomarker for the risk of alemtuzumab-induced autoimmunity. [ABSTRACT FROM AUTHOR]

Objective: Direct pathogenic effects of autoantibodies to the 65 kDa isoform of glutamic acid decarboxylase (GAD65) in autoimmune limbic encephalitis (LE) have been questioned due to its intracellular localization. We therefore hypothesized a pathogenic role for T cells. Methods: We assessed magnet resonance imaging, neuropsychological and peripheral blood, and CSF flow cytometry data of 10 patients with long‐standing GAD65‐LE compared to controls in a cross‐sectional manner. These data were related to each other within the GAD65‐LE group and linked to neuropathological findings in selective hippocampectomy specimen from another two patients. In addition, full‐resolution human leukocyte antigen (HLA) genotyping of all patients was performed. Results: Compared to controls, no alteration in hippocampal volume but impaired memory function and elevated fractions of activated HLADR+ CD4+ and CD8+ T cells in peripheral blood and cerebrospinal fluid were found. Intrathecal fractions of CD8+ T cells negatively correlated with hippocampal volume and memory function, whereas the opposite was true for CD4+ T cells. Consistently, antigen‐experienced CD8+ T cells expressed increased levels of the cytotoxic effector molecule perforin in peripheral blood, and perforin‐expressing CD8+ T cells were found attached mainly to small interneurons but also to large principal neurons together with wide‐spread hippocampal neurodegeneration. 6/10 LE patients harbored the HLA‐A*02:01 allele known to present the immunodominant GAD65114–123 peptide in humans. Interpretation: Our data suggest a pathogenic effect of CD8+ T cells and a regulatory effect of CD4+ T cells in patients with long‐standing GAD65‐LE. [ABSTRACT FROM AUTHOR]

Objective: Neurological manifestations of autoimmune connective tissue diseases (CTD) are poorly understood and difficult to diagnose. We here aimed to address this shortcoming by studying immune cell compositions in CTD patients with and without neurological manifestation. Methods: Using flow cytometry, we retrospectively investigated paired cerebrospinal fluid (CSF) and blood samples of 28 CTD patients without neurological manifestation, 38 CTD patients with neurological manifestation (N-CTD), 38 non-inflammatory controls, and 38 multiple sclerosis (MS) patients, a paradigmatic primary neuroinflammatory disease. Results: We detected an expansion of plasma cells in the blood of both N-CTD and CTD compared to non-inflammatory controls and MS. Blood plasma cells alone distinguished the clinically similar entities N-CTD and MS with high discriminatory performance (AUC: 0.81). Classical blood monocytes indicated higher disease activity in systemic lupus erythematosus (SLE) patients. Surprisingly, immune cells in the CSF did not differ significantly between N-CTD and CTD, while CD4+ T cells and the CD4+/CD8+ ratio were elevated in the blood of N-CTD compared to CTD. Several B cell-associated parameters partially overlapped in the CSF in MS and N-CTD. We built a machine learning model that distinguished N-CTD from MS with high discriminatory power using either blood or CSF. Conclusion: We here find that blood flow cytometry alone surprisingly suffices to distinguish CTD with neurological manifestations from clinically similar entities, suggesting that a rapid blood test could support clinicians in the differential diagnosis of N-CTD. [ABSTRACT FROM AUTHOR]

After natalizumab (NAT) cessation, some multiple sclerosis (MS) patients experience a severe disease rebound. The rebound pathophysiology is still unclear; however, it has been linked to interleukin-17-producing T-helper (Th17) cells. We demonstrate that during NAT treatment, MCAM+CCR6+Th17 cells gradually acquire a pathogenic profile, including proinflammatory cytokine production, pathogenic transcriptional signatures, brain endothelial barrier impairment, and oligodendrocyte damage via induction of apoptotic pathways. This is accompanied by an increase in Th17 cell frequencies in the cerebrospinal fluid of NAT-treated patients. Notably, Th17 cells derived from NAT-treated patients, who later developed a disease rebound upon treatment cessation, displayed a distinct transcriptional pathogenicity profile associated with altered migratory properties. Accordingly, increased brain infiltration of patient Th17 cells was illustrated in a humanized mouse model and brain histology from a rebound patient. Therefore, peripheral blood-accumulated MCAM+CCR6+Th17 cells might be involved in rebound pathophysiology, and monitoring of changes in Th17 cell pathogenicity in patients before/during NAT treatment cessation might enable rebound risk assessment in the future. [ABSTRACT FROM AUTHOR]

Background: Primary central nervous system lymphoma (PCNSL) is a rare lymphoma of the central nervous system, usually of diffuse large B cell phenotype. Stereotactic biopsy followed by histopathology is the diagnostic standard. However, limited material is available from CNS biopsies, thus impeding an in-depth characterization of PCNSL. Methods: We performed flow cytometry, single-cell RNA sequencing, and B cell receptor sequencing of PCNSL cells released from biopsy material, blood, and cerebrospinal fluid (CSF), and spatial transcriptomics of biopsy samples. Results: PCNSL-released cells were predominantly activated CD19+CD20+CD38+CD27+ B cells. In single-cell RNA sequencing, PCNSL cells were transcriptionally heterogeneous, forming multiple malignant B cell clusters. Hyperexpanded B cell clones were shared between biopsy- and CSF- but not blood-derived cells. T cells in the tumor microenvironment upregulated immune checkpoint molecules, thereby recognizing immune evasion signals from PCNSL cells. Spatial transcriptomics revealed heterogeneous spatial organization of malignant B cell clusters, mirroring their transcriptional heterogeneity across patients, and pronounced expression of T cell exhaustion markers, co-localizing with a highly malignant B cell cluster. Conclusions: Malignant B cells in PCNSL show transcriptional and spatial intratumor heterogeneity. T cell exhaustion is frequent in the PCNSL microenvironment, co-localizes with malignant cells, and highlights the potential of personalized treatments. [ABSTRACT FROM AUTHOR]

Objective: Intravenous methylprednisolone is the standard treatment for a multiple sclerosis relapse; however, this fails to improve symptoms in up to one quarter of patients. Immunoadsorption is an accepted treatment for refractory relapses, but prospective comparator-controlled studies are missing.Methods: In this observational study, patients with steroid-refractory acute multiple sclerosis relapses receiving either six courses of tryptophan-immunoadsorption or double-dose methylprednisolone therapy were analysed. Outcomes were evaluated at discharge and three months later. Immune profiling of blood lymphocytes and proteomic analysis were performed by multi-parameter flow cytometry and Olink analysis, respectively (NCT04450030).Results: 42 patients were enrolled (methylprednisolone: 26 patients; immunoadsorption: 16 patients). For determination of the primary outcome, treatment response was stratified according to relative function system score changes ("full/best" vs. "average" vs. "worse/none"). Upon discharge, the adjusted odds ratio for any treatment response ("full/best" + "average" vs. "worse/none") was 10.697 favouring immunoadsorption (p = 0.005 compared to methylprednisolone). At follow-up, the adjusted odds ratio for the best treatment response ("full/best" vs. "average" + "worse/none") was 103.236 favouring IA patients (p = 0.001 compared to methylprednisolone). Similar results were observed regarding evoked potentials and quality of life outcomes, as well as serum neurofilament light-chain levels. Flow cytometry revealed a profound reduction of B cell subsets following immunoadsorption, which was closely correlated to clinical outcomes, whereas methylprednisolone had a minimal effect on B cell populations. Immunoadsorption treatment skewed the blood cytokine network, reduced levels of B cell-related cytokines and reduced immunoglobulin levels as well as levels of certain coagulation factors.Interpretation: Immunoadsorption demonstrated favourable outcomes compared to double-dose methylprednisolone. Outcome differences were significant at discharge and follow-up. Further analyses identified modulation of B cell function as a potential mechanism of action for immunoadsorption, as reduction of B cell subsets correlated with clinical improvement. [ABSTRACT FROM AUTHOR]

Killer cell immunoglobulin-like receptors (KIRs) comprise a group of highly polymorphic inhibitory receptors which are specific for classical HLA class-I molecules. Peripheral blood and freshly prepared tumor cell suspensions (n = 60) as well as control samples (n = 32) were investigated for the distribution, phenotype, and functional relevance of CD158ab/KIR2DL1,-2/3 expressing NK-cells in glioblastoma (GBM) patients. We found that GBM were scarcely infiltrated by NK-cells that preferentially expressed CD158ab/KIR2DL1,-2/3 as inhibitory receptors, displayed reduced levels of the activating receptors CD335/NKp46, CD226/DNAM-1, CD159c/NKG2C, and showed diminished capacity to produce IFN-γ and perforin. Functional hypoactivity of GBM-derived NK-cells persisted despite IL-2 preactivation. Blockade with a specific KIR2DL-1,2/3 monoclonal antibody reversed NK-cell inhibition and significantly enhanced degranulation and IFN-γ production of IL-2 preactivated NK-cells in the presence of primary GBM cells and HLA-C expressing but not HLA class-I deficient K562 cells. Additional analysis revealed that significant amounts of IL-2 could be produced by tumor-derived CD4+ and CD8+CD45RA- memory T-cells after combined anti-CD3/anti-CD28 stimulation. Our data indicate that both blockade of inhibitory KIR and IL-2 triggering of tumor-derived NK-cells are necessary to enhance NK-cell responsiveness in GBM. [ABSTRACT FROM AUTHOR]

Dimethyl fumarate, an approved treatment for relapsing-remitting multiple sclerosis, exerts pleiotropic effects on immune cells as well as CNS resident cells. Here, we show that dimethyl fumarate exerts a profound alteration of the metabolic profile of human CD4+ as well as CD8+ T cells and restricts their antioxidative capacities by decreasing intracellular levels of the reactive oxygen species scavenger glutathione. This causes an increase in mitochondrial reactive oxygen species levels accompanied by an enhanced mitochondrial stress response, ultimately leading to impaired mitochondrial function. Enhanced mitochondrial reactive oxygen species levels not only result in enhanced T-cell apoptosis in vitro as well as in dimethyl fumarate-treated patients, but are key for the well-known immunomodulatory effects of dimethyl fumarate both in vitro and in an animal model of multiple sclerosis, i.e. experimental autoimmune encephalomyelitis. Indeed, dimethyl fumarate immune-modulatory effects on T cells were completely abrogated by pharmacological interference of mitochondrial reactive oxygen species production. These data shed new light on dimethyl fumarate as bona fide immune-metabolic drug that targets the intracellular stress response in activated T cells, thereby restricting mitochondrial function and energetic capacity, providing novel insight into the role of oxidative stress in modulating cellular immune responses and T cell-mediated autoimmunity. [ABSTRACT FROM AUTHOR]