Effect of natalizumab on circulating CD4+ T-cells in multiple sclerosis

Long-term effectiveness of natalizumab in secondary progressive multiple sclerosis: A propensity-matched study

Treatment options for secondary progressive MS (SPMS) are limited, especially considering that the new drugs recently approved are licensed for actively relapsing patients. We aimed to compare the disability progression in a real-world cohort of SPMS patients treated with natalizumab (NTZ) or interferon beta-1b (IFNb-1b). This multicenter retrospective enrolled patients with a diagnosis of SPMS according to 2014 Lublin criteria, who received NTZ or IFNb-1b for at least 48 months between the 1st June 2012 and the 15th May 2018 ​at 33 Italian MS centers contributing to the Italian MS Registry NTZ or IFNb-1b. Confirmed Expanded Disability Status Scale worsening (CEW) and progression independent of relapse (PIRA) were evaluated. In order to correct for non-randomization, a propensity score matching of the groups was performed. Out of 5206 MS patients identified at the time of data extraction, 421 SPMS patients treated with NTZ (224 [53.2%] females, mean age 45.3 ​± ​25.4 years) and 353 with IFNb-1b (133 [37.8%] females, mean age 48.5 ​± ​19.8 years) were enrolled. After applying the matching procedure, 102 patients were retained in the NTZ group and 98 in the IFNb-2b group. The proportion of patients who reached the 48-month 1-point CEW was significantly higher in IFNb-1b compared to NTZ group (58.2% versus 30.4%, p ​= ​0.01). The proportion of patients who developed PIRA at 48 months were significantly higher in IFNb-1b compared to NTZ (72.4% versus 40.2%, p ​= ​0.01). EDSS before treatment initiation and SPMS duration were risk factors for disability progression in terms of PIRA (HR 2.54, 25%CI 1.67-5.7; p ​= ​0.006 and HR 2.04, 25%CI 1.22-3.35; p ​= ​0.01, respectively). Patients treated with IFNb-1b were 1.64 times more to likely to develop PIRA (HR 1.64, 25%CI 1.04-4.87; p ​= ​0.001). Treatment with NTZ in SPMS patients showed more favorable disability outcomes compared to IFNb-1b with beneficial effects over 48 months.

Effect of siponimod on lymphocyte subsets in active secondary progressive multiple sclerosis and clinical implications

BACKGROUND

Circulating immune cells play a pathogenic role in multiple sclerosis (MS). However, the role of specific lymphocyte subpopulations is not unveiled yet, especially in progressive stages. We aimed to investigate lymphocyte changes during siponimod treatment in active secondary progressive MS (aSPMS) and their associations with clinical outcomes.

METHODS

We enrolled 46 aSPMS patients starting on siponimod treatment with at least 6 months of follow-up and two visits within the scheduled timeframes and 14 sex- and age-matched healthy controls (HCs). Clinical and laboratory data were collected retrospectively at baseline, 3rd, 6th, 12th, and 24th month for MS patients, and at baseline for HCs.

RESULTS

At baseline SPMS patients presented with increased naïve regulatory T lymphocytes (p = 0.02) vs. HCs. Over time, SPMS patients showed decreased T CD4+ (coeff. range = -24/-17, 95% CI range = -31.60 to -10.40), B lymphocyte (coeff. range = -3.77/-2.54, 95% CI range = -6.02 to -0.35), memory regulatory B cells (coeff. range = -0.78/-0.57, 95% CI range = -1.24 to -0.17) and CD4/CD8 ratio (coeff. range = -4.44/-0.67, 95% CI range = -1.61 to -0.17) from month 3 thereafter vs. baseline, and reduced CD3+CD20+ lymphocytes from month 12 thereafter (coeff. range = -0.32/-0.24, 95% CI range = -0.59 to -0.03). Patients not experiencing disability progression while on siponimod treatment showed B lymphocyte reduction from month 3 (coeff. range = -4.23/-2.32, 95% CI range = -7.53 to -0.15) and CD3+CD20+ lymphocyte reduction from month 12 (coeff. range = -0.32/-0.24, 95% CI range = -0.59 to -0.03) vs. patients experiencing progression.

CONCLUSIONS

Patients treated with siponimod showed a T and B lymphocyte reduction, especially CD4+, CD3+CD20+ and naïve regulatory T cells and memory regulatory B cells. Disability progression while on siponimod treatment was associated with a less pronounced effect on B and CD3+CD20+ lymphocytes.

OX40 (CD134) Expression on T Regulatory Cells Is Related to Serious Hypertensive Disorders in Pregnancy

Hypertension is one of the leading causes of morbidity and mortality among women related to pregnancy, childbirth and the postpartum period. The pathogenesis of gestational hypertension is complex and still not fully understood. The aim of this study was to assess the population of circulating CD4+CD25+FoxP3+ cells and its differentiation in terms of OX40 expression in two forms of hypertension: isolated hypertension developing after the 20th week of pregnancy and pre-eclampsia. The study included a group of 60 patients with hypertension and 48 healthy controls. The analysis of the percentage of Tregs was performed by flow cytometry. There was no difference in the percentage of peripheral lymphocytes between the groups. In the group of women with preeclampsia compared to the group with gestational hypertension, significantly higher percentages of CD4+CD25+FoxP3+ cells (p = 0.03) and percentages of CD4+CD25+FoxP3+ cells expressing the OX40 antigen (p = 0.001) were observed. OX40 expression on Tregs seems to be related to more serious type of hypertensive disorders in pregnant women.

Comparison of OX40 expression in patients with multiple sclerosis and neuromyelitis optica as an approach to diagnosis

BACKGROUND

Previous studies have shown that CD134 (OX40) co-stimulation is involved in the pathogenesis of experimental autoimmune encephalomyelitis (EAE) models and the antigen is expressed within multiple sclerosis lesions in humans. OX40 (CD134) is thought to be a secondary co-stimulatory immune checkpoint molecule that is expressed by T cells. This study aimed to evaluate the mRNA expression of OX40 and its serum levels in the peripheral blood of patients with Multiple Sclerosis (MS) or Neuromyelitis Optica (NMO).

METHODS

Patients with MS (n = 60), NMO (n = 20), and 20 healthy subjects were recruited from Sina Hospital, Tehran, Iran. The diagnoses were confirmed by a specialist in clinical neurology. Peripheral venous blood was obtained from all subjects, and mRNA quantification of OX40 was conducted using real-time PCR. Serum samples were also obtained and the concentration of OX40 was determined using an enzyme-linked immunosorbent assay (ELISA).

RESULTS

There was a significant correlation between the mRNA expression and serum levels of OX40 and disability as assessed using the expanded disability status scale (EDSS) in the patients with MS, but not in the patients with NMO. Expression of OX40 mRNA was significantly higher in the peripheral blood of MS patients compared to healthy individuals and NMO patients (*P < 0.05). In addition, serum OX40 concentrations were also significantly higher in patients with MS patients compared with healthy subjects (9.08 ± 2.48 vs. 1.49 ± 0.54 ng/ml; P = 0.041).

CONCLUSIONS

It appears that an increased expression of OX40 may be associated with the hyperactivation of T cells in patients with MS, and this may play a role in the pathogenesis of the disease.

T Lymphocyte Serotonin 5-HT7 Receptor Is Dysregulated in Natalizumab-Treated Multiple Sclerosis Patients

Serotonin (5-HT) is known as a potent immune cell modulator in autoimmune diseases and should be protective in the pathogenesis of multiple sclerosis (MS). Nevertheless, there is limited knowledge about receptors involved in 5-HT effects as well as induced mechanisms. Among 5-HT receptors, the 5-HT₇ receptor is able to activate naïve T cells and influence the inflammatory response; however, its involvement in the disease has never been studied so far. In this study, we collected blood sample from three groups: acute relapsing MS patients (ARMS), natalizumab-treated MS patients (NTZ), and control subjects. We investigated the 5-HT₇ expression on circulating lymphocytes and evaluated the effects of its activation on cytokine production with peripheral blood mononuclear cell (PBMC) cultures. We found a significant increase in the 5-HT₇ surface expression on T lymphocytes and on the different CD4⁺ T cell subsets exclusively in NTZ-treated patients. We also showed that the selective agonist 5-carboxamidotryptamine (5-CT)-induced 5-HT₇R activation significantly promotes the production of IL-10, a potent immunosuppressive cytokine in PBMCs. This study provides for the first time a dysregulation of 5-HT₇ expression in NTZ-MS patients and its ability to promote IL-10 release, suggesting its protective role. These findings strengthen the evidence that 5-HT₇ may play a role in the immuno-protective mechanisms of NTZ in MS disease and could be considered as an interesting therapeutic target in MS.

Activation Markers on B and T Cells and Immune Checkpoints in Autoimmune Rheumatic Diseases

In addition to identifying the major B- and T-cell subpopulations involved in autoimmune rheumatic diseases (ARDs), in recent years special attention has been paid to studying the expression of their activation markers and immune checkpoints (ICPs). The activation markers on B and T cells are a consequence of the immune response, and these molecules are considered as sensitive specific markers of ARD activity and as promising targets for immunotherapy. ICPs regulate the activation of the immune response by preventing the initiation of autoimmune processes, and they modulate it by reducing immune cell-induced organ and tissue damage. The article considers the possible correlation of ICPs with the activity of ARDs, the efficacy of specific ARD treatments, and the prospects for the use of activation molecules and activation/blocking ICPs for the treatment of ARDs.

High-dimensional immune profiling identifies a biomarker to monitor dimethyl fumarate response in multiple sclerosis

Dimethyl fumarate (DMF) is an immunomodulatory treatment for multiple sclerosis (MS). Despite its wide clinical use, the mechanisms underlying clinical response are not understood. This study aimed to reveal immune markers of therapeutic response to DMF treatment in MS. For this purpose, we prospectively collected peripheral blood mononuclear cells (PBMCs) from a highly characterized cohort of 44 individuals with MS before and at 12 and 48 wk of DMF treatment. Single cells were profiled using high-dimensional mass cytometry. To capture the heterogeneity of different immune subsets, we adopted a bioinformatic multipanel approach that allowed cell population-cluster assignment of more than 50 different parameters, including lineage and activation markers as well as chemokine receptors and cytokines. Data were further analyzed in a semiunbiased fashion implementing a supervised representation learning approach to capture subtle longitudinal immune changes characteristic for therapy response. With this approach, we identified a population of memory T helper cells expressing high levels of neuroinflammatory cytokines (granulocyte-macrophage colony-stimulating factor [GM-CSF], interferon γ [IFNγ]) as well as CXCR3, whose abundance correlated with treatment response. Using spectral flow cytometry, we confirmed these findings in a second cohort of patients. Serum neurofilament light-chain levels confirmed the correlation of this immune cell signature with axonal damage. The identified cell population is expanded in peripheral blood under natalizumab treatment, substantiating a specific role in treatment response. We propose that depletion of GM-CSF-, IFNγ-, and CXCR3-expressing T helper cells is the main mechanism of action of DMF and allows monitoring of treatment response.

Identification of four novel T cell autoantigens and personal autoreactive profiles in multiple sclerosis

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system (CNS), in which pathological T cells, likely autoimmune, play a key role. Despite its central importance, the autoantigen repertoire remains largely uncharacterized. Using a novel in vitro antigen delivery method combined with the Human Protein Atlas library, we screened for T cell autoreactivity against 63 CNS-expressed proteins. We identified four previously unreported autoantigens in MS: fatty acid-binding protein 7, prokineticin-2, reticulon-3, and synaptosomal-associated protein 91, which were verified to induce interferon-γ responses in MS in two cohorts. Autoreactive profiles were heterogeneous, and reactivity to several autoantigens was MS-selective. Autoreactive T cells were predominantly CD4⁺ and human leukocyte antigen-DR restricted. Mouse immunization induced antigen-specific responses and CNS leukocyte infiltration. This represents one of the largest systematic efforts to date in the search for MS autoantigens, demonstrates the heterogeneity of autoreactive profiles, and highlights promising targets for future diagnostic tools and immunomodulatory therapies in MS.

Secondary Immunodeficiency and Risk of Infection Following Immune Therapies in Neurology

Secondary immunodeficiencies (SIDs) are acquired conditions that may occur as sequelae of immune therapy. In recent years a number of disease-modifying therapies (DMTs) has been approved for multiple sclerosis and related disorders such as neuromyelitis optica spectrum disorders, some of which are frequently also used in- or off-label to treat conditions such as chronic inflammatory demyelinating polyneuropathy (CIDP), myasthenia gravis, myositis, and encephalitis. In this review, we focus on currently available immune therapeutics in neurology to explore their specific modes of action that might contribute to SID, with particular emphasis on their potential to induce secondary antibody deficiency. Considering evidence from clinical trials as well as long-term observational studies related to the patients' immune status and risks of severe infections, we delineate long-term anti-CD20 therapy, with the greatest data availability for rituximab, as a major risk factor for the development of SID, particularly through secondary antibody deficiency. Alemtuzumab and cladribine have relevant effects on circulating B-cell counts; however, evidence for SID mediated by antibody deficiency appears limited and urgently warrants further systematic evaluation. To date, there has been no evidence suggesting that treatment with fingolimod, dimethyl fumarate, or natalizumab leads to antibody deficiency. Risk factors predisposing to development of SID include duration of therapy, increasing age, and pre-existing low immunoglobulin (Ig) levels. Prevention strategies of SID comprise awareness of risk factors, individualized treatment protocols, and vaccination concepts. Immune supplementation employing Ig replacement therapy might reduce morbidity and mortality associated with SIDs in neurological conditions. In light of the broad range of existing and emerging therapies, the potential for SID warrants urgent consideration among neurologists and other healthcare professionals.

The OX40/OX40L Axis Regulates T Follicular Helper Cell Differentiation: Implications for Autoimmune Diseases

T Follicular helper (Tfh) cells, a unique subset of CD4⁺ T cells, play an essential role in B cell development and the formation of germinal centers (GCs). Tfh differentiation depends on various factors including cytokines, transcription factors and multiple costimulatory molecules. Given that OX40 signaling is critical for costimulating T cell activation and function, its roles in regulating Tfh cells have attracted widespread attention. Recent data have shown that OX40/OX40L signaling can not only promote Tfh cell differentiation and maintain cell survival, but also enhance the helper function of Tfh for B cells. Moreover, upregulated OX40 signaling is related to abnormal Tfh activity that causes autoimmune diseases. This review describes the roles of OX40/OX40L in Tfh biology, including the mechanisms by which OX40 signaling regulates Tfh cell differentiation and functions, and their close relationship with autoimmune diseases.

Immune repertoire: Revealing the "real-time" adaptive immune response in autoimmune diseases

The diversity of the immune repertoire (IR) enables the human immune system to distinguish multifarious antigens (Ags) that humans may encounter throughout life. At the same time, bias or abnormalities in the IR also pay a contribution to the pathogenesis of autoimmune diseases. Rapid advancements in high-throughput sequencing (HTS) technology have ushered in a new era of immune studies, revealing novel molecules and pathways that might result in autoimmunity. In the field of IR, HTS can monitor the immune response status and identify disease-specific immune repertoires. In this review, we summarize updated progress on the mechanisms of the IR and current related studies on four autoimmune diseases, particularly focusing on systemic lupus erythematosus (SLE). These autoimmune diseases can exhibit slightly or significantly skewed IRs and provide novel insights that inform our comprehending of disease pathogenesis and provide potential targets for diagnosis and treatment.

Extensive Healthy Donor Age/Gender Adjustments and Propensity Score Matching Reveal Physiology of Multiple Sclerosis Through Immunophenotyping

Quantifying cell subpopulations in biological fluids aids in diagnosis and understanding of the mechanisms of injury. Although much has been learned from cerebrospinal fluid (CSF) flow cytometry in neuroimmunological disorders, such as multiple sclerosis (MS), previous studies did not contain enough healthy donors (HD) to derive age- and gender-related normative data and sufficient heterogeneity of other inflammatory neurological disease (OIND) controls to identify MS specific changes. The goals of this blinded training and validation study of MS patients and embedded controls, representing 1,240 prospectively acquired paired CSF/blood samples from 588 subjects was (1) to define physiological age-/gender-related changes in CSF cells, (2) to define/validate cellular abnormalities in blood and CSF of untreated MS through disease duration (DD) and determine which are MS-specific, and (3) to compare effect(s) of low-efficacy (i.e., interferon-beta [IFN-beta] and glatiramer acetate [GA]) and high-efficacy drugs (i.e., natalizumab, daclizumab, and ocrelizumab) on MS-related cellular abnormalities using propensity score matching. Physiological gender differences are less pronounced in the CSF compared to blood, and age-related changes suggest decreased immunosurveillance of CNS by activated HLA-DR+T cells associated with natural aging. Results from patient samples support the concept of MS being immunologically single disease evolving in time. Initially, peripherally activated innate and adaptive immune cells migrate into CSF to form MS lesions. With progression, T cells (CD8+ > CD4+), NK cells, and myeloid dendritic cells are depleted from blood as they continue to accumulate, together with B cells, in the CSF and migrate to CNS tissue, forming compartmentalized inflammation. All MS drugs inhibit non-physiological accumulation of immune cells in the CSF. Although low-efficacy drugs tend to normalize it, high-efficacy drugs overshoot some aspects of CSF physiology, suggesting impairment of CNS immunosurveillance. Comparable inhibition of MS-related CSF abnormalities advocates changes within CNS parenchyma responsible for differences in drug efficacy on MS disability progression. Video summarizing all results may become useful educational tool.

Natalizumab in Multiple Sclerosis Treatment: From Biological Effects to Immune Monitoring

Multiple sclerosis is a chronic demyelinating disease of the central nervous system (CNS) with an autoimmune component. Among the recent disease-modifying treatments available, Natalizumab, a monoclonal antibody directed against the alpha chain of the VLA-4 integrin (CD49d), is a potent inhibitor of cell migration toward the tissues including CNS. It potently reduces relapses and active brain lesions in the relapsing remitting form of the disease. However, it has also been associated with a severe infectious complication, the progressive multifocal leukoencephalitis (PML). Using the standard protocol with an injection every 4 weeks it has been shown by a close monitoring of the drug that trough levels soon reach a plateau with an almost saturation of the target cell receptor as well as a down modulation of this receptor. In this review, mechanisms of action involved in therapeutic efficacy as well as in PML risk will be discussed. Furthermore the interest of a biological monitoring that may be helpful to rapidly adapt treatment is presented. Indeed, development of anti-NAT antibodies, although sometimes unapparent, can be detected indirectly by normalization of CD49d expression on circulating mononuclear cells and might require to switch to another drug. On the other hand a stable modulation of CD49d expression might be useful to follow the circulating NAT levels and apply an extended interval dose scheme that could contribute to limiting the risk of PML.

Whole transcriptome analysis of multiple Sclerosis patients reveals active inflammatory profile in relapsing patients and downregulation of neurological repair pathways in secondary progressive cases

BACKGROUND

Multiple sclerosis (MS) is an inflammatory autoimmune neurologic disease that causes progressive destruction of myelin sheath and axons. Affecting more than 2 million people worldwide, MS may presents distinct clinical courses. However, information regarding key gene expression and genic pathways related to each clinical form is still limited.

OBJECTIVE

To assess the whole transcriptome of blood leukocytes from patients with remittent-recurrent (RRMS) and secondary-progressive (SPMS) forms to explore the gene expression profile of each form.

METHODS

Total RNA was obtained and sequenced in Illumina HiSeq platform. Reads were aligned to human genome (GRCh38/hg38), BAM files were mapped and differential expression was obtained with DeSeq2. Up or downregulated pathways were obtained through Ingenuity IPA. Pro-inflammatory cytokines levels were also assessed.

RESULTS

The transcriptome was generated for nine patients (6 SPMS and 3 RRMS) and 5 healthy controls. A total of 731 and 435 differentially expressed genes were identified in SPMS and RRMS, respectively. RERE, IRS2, SIPA1L1, TANC2 and PLAGL1 were upregulated in both forms, whereas PAD2 and PAD4 were upregulated in RRMS and downregulated in SPMS. Inflammatory and neuronal repair pathways were upregulated in RRMS, which was also observed in cytokine analysis. Conversely, SPMS patients presented IL-8, IL-1, Neurothrophin and Neuregulin pathways down regulated.

CONCLUSIONS

Overall, the transcriptome of RRMS and SPMS clearly indicated distinct inflammatory profiles, where RRMS presented marked pro-inflammatory profile but SPMS did not. SPMS individuals also presented a decrease on expression of neuronal repair pathways.

Blockade of VLA4 sensitizes leukemic and myeloma tumor cells to CD3 redirection in the bone marrow microenvironment

Redirecting T cells to specifically kill malignant cells has been validated as an effective anti-cancer strategy in the clinic with the approval of blinatumomab for acute lymphoblastic leukemia. However, the immunosuppressive nature of the tumor microenvironment potentially poses a significant hurdle to T cell therapies. In hematological malignancies, the bone marrow (BM) niche is protective to leukemic stem cells and has minimized the efficacy of several anti-cancer drugs. In this study, we investigated the impact of the BM microenvironment on T cell redirection. Using bispecific antibodies targeting specific tumor antigens (CD123 and BCMA) and CD3, we observed that co-culture of acute myeloid leukemia or multiple myeloma cells with BM stromal cells protected tumor cells from bispecific antibody-T cell-mediated lysis in vitro and in vivo. Impaired CD3 redirection cytotoxicity was correlated with reduced T cell effector responses and cell-cell contact with stromal cells was implicated in reducing T cell activation and conferring protection of cancer cells. Finally, blocking the VLA4 adhesion pathway in combination with CD3 redirection reduced the stromal-mediated inhibition of cytotoxicity and T cell activation. Our results lend support to inhibiting VLA4 interactions along with administering CD3 redirection therapeutics as a novel combinatorial regimen for robust anti-cancer responses.

The TCR Repertoire Reconstitution in Multiple Sclerosis: Comparing One-Shot and Continuous Immunosuppressive Therapies

Natalizumab (NTZ) and autologous hematopoietic stem cell transplantation (AHSCT) are two successful treatments for relapsing-remitting multiple sclerosis (RRMS), an autoimmune T-cell-driven disorder affecting the central nervous system that is characterized by relapses interspersed with periods of complete or partial recovery. Both RRMS treatments have been documented to impact T-cell subpopulations and the T-cell receptor (TCR) repertoire in terms of clone frequency, but, so far, the link between T-cell naive and memory populations, autoimmunity, and treatment outcome has not yet been established hindering insight into the post-treatment TCR landscape of MS patients. To address this important knowledge gap, we tracked peripheral T-cell subpopulations (naïve and memory CD4+ and CD8+) across 15 RRMS patients before and after two years of continuous treatment (NTZ) and a single treatment course (AHSCT) by high-throughput TCRß sequencing. We found that the two MS treatments left treatment-specific multidimensional traces in patient TCRß repertoire dynamics with respect to clonal expansion, clonal diversity and repertoire architecture. Comparing MS TCR sequences with published datasets suggested that the majority of public TCRs belonged to virus-associated sequences. In summary, applying multi-dimensional computational immunology to a TCRß dataset of treated MS patients, we show that qualitative changes of TCRß repertoires encode treatment-specific information that may be relevant for future clinical trials monitoring and personalized MS follow-up, diagnosis and treatment regimes. Natalizumab (NTZ) and autologous hematopoietic stem cell transplantation (AHSCT) are two successful treatments for relapsing-remitting multiple sclerosis (RRMS), an autoimmune T-cell-driven disorder affecting the central nervous system that is characterized by relapses interspersed with periods of complete or partial recovery. Both RRMS treatments have been documented to impact T-cell subpopulations and the T-cell receptor (TCR) repertoire in terms of clone frequency, but, so far, the link between T-cell naive and memory populations, autoimmunity, and treatment outcome has not yet been established hindering insight into the posttreatment TCR landscape of MS patients. To address this important knowledge gap, we tracked peripheral T-cell subpopulations (naive and memory CD4+ and CD8+) across 15 RRMS patients before and after 2 years of continuous treatment (NTZ) and a single treatment course (AHSCT) by high-throughput TCRβ sequencing. We found that the two MS treatments left treatment-specific multidimensional traces in patient TCRβ repertoire dynamics with respect to clonal expansion, clonal diversity, and repertoire architecture. Comparing MS TCR sequences with published datasets suggested that the majority of public TCRs belonged to virus-associated sequences. In summary, applying multidimensional computational immunology to a TCRβ dataset of treated MS patients, we show that qualitative changes of TCRβ repertoires encode treatment-specific information that may be relevant for future clinical trials monitoring and personalized MS follow-up, diagnosis, and treatment regimens.

Gut microbiota-dependent CCR9+CD4+ T cells are altered in secondary progressive multiple sclerosis

The mechanism underlying the progression of relapsing-remitting multiple sclerosis to secondary progressive multiple sclerosis (SPMS), characterized by accumulating fixed disability, is yet to be fully understood. Although alterations in the gut microbiota have recently been highlighted in multiple sclerosis pathogenesis, the mechanism linking the altered gut environment with the remote CNS pathology remains unclear. Here, we analyse human CD4⁺ memory T cells expressing the gut-homing chemokine receptor CCR9 and found a reduced frequency of CCR9⁺ memory T cells in the peripheral blood of patients with SPMS relative to healthy controls. The reduction in the proportion of CCR9⁺ cells among CD4⁺ memory T cells (%CCR9) in SPMS did not correlate with age, disease duration or expanded disability status scale score, although %CCR9 decreased linearly with age in healthy controls. During the clinical relapse of both, relapsing-remitting multiple sclerosis and neuromyelitis optica, a high proportion of cells expressing the lymphocyte activating 3 gene (LAG3) was detected among CCR9⁺ memory T cells isolated from the CSF, similar to that observed for mouse regulatory intraepithelial lymphocytes. In healthy individuals, CCR9⁺ memory T cells expressed higher levels of CCR6, a CNS-homing chemokine receptor, and exhibited a regulatory profile characterized by both the expression of C-MAF and the production of IL-4 and IL-10. However, in CCR9⁺ memory T cells, the expression of RORγt was specifically upregulated, and the production of IL-17A and IFNγ was high in patients with SPMS, indicating a loss of regulatory function. The evaluation of other cytokines supported the finding that CCR9⁺ memory T cells acquire a more inflammatory profile in SPMS, reporting similar aspects to CCR9⁺ memory T cells of the elderly healthy controls. CCR9⁺ memory T cell frequency decreased in germ-free mice, whereas antibiotic treatment increased their number in specific pathogen-free conditions. Here, we also demonstrate that CCR9⁺ memory T cells preferentially infiltrate into the inflamed CNS resulting from the initial phase and that they express LAG3 in the late phase in the experimental autoimmune encephalomyelitis mouse model of multiple sclerosis. Antibiotic treatment reduced experimental autoimmune encephalomyelitis symptoms and was accompanied by an increase in CCR9⁺ memory T cells in the peripheral blood. Antibodies against mucosal vascular addressin cell adhesion molecule 1 (MADCAM1), which is capable of blocking cell migration to the gut, also ameliorated experimental autoimmune encephalomyelitis. Overall, we postulate that the alterations in CCR9⁺ memory T cells observed, caused by either the gut microbiota changes or ageing, may lead to the development of SPMS.

Myelin oligodendrocyte glycoprotein revisited-sensitive detection of MOG-specific T-cells in multiple sclerosis

Autoreactive CD4+ T-cells are believed to be a main driver of multiple sclerosis (MS). Myelin oligodendrocyte glycoprotein (MOG) is considered an autoantigen, yet doubted in recent years. The reason is in part due to low frequency and titers of MOG autoantibodies and the challenge to detect MOG-specific T-cells. In this study we aimed to analyze T-cell reactivity and frequency utilizing a novel method for detection of antigen-specific T-cells with bead-bound MOG as stimulant. Peripheral blood mononuclear cells (PBMCs) from natalizumab treated persons with MS (n = 52) and healthy controls (HCs) (n = 24) were analyzed by IFNγ/IL-22/IL-17A FluoroSpot. A higher number of IFNγ (P = 0.001), IL-22 (P = 0.003), IL-17A (P < 0.0001) as well as double and triple cytokine producing MOG-specific T-cells were detected in persons with MS compared to HCs. Of the patients, 46.2-59.6% displayed MOG-reactivity. Depletion of CD4+ T-cells or monocytes or blocking HLA-DR completely eliminated the MOG specific response. Anti-MOG antibodies did not correlate with T-cell MOG-responses. In conclusion, we present a sensitive method to detect circulating autoreactive CD4+ T-cells producing IFNγ, IL-22 or IL-17A using MOG as a model antigen. Further, we demonstrate that MOG-specific T-cells are present in approximately half of persons with MS.

To the Brain and Back: Migratory Paths of Dendritic Cells in Multiple Sclerosis

Migration of dendritic cells (DC) to the central nervous system (CNS) is a critical event in the pathogenesis of multiple sclerosis (MS). While up until now, research has mainly focused on the transmigration of DC through the blood-brain barrier, experimental evidence points out that also the choroid plexus and meningeal vessels represent important gateways to the CNS, especially in early disease stages. On the other hand, DC can exit the CNS to maintain immunological tolerance to patterns expressed in the CNS, a process that is perturbed in MS. Targeting trafficking of immune cells, including DC, to the CNS has demonstrated to be a successful strategy to treat MS. However, this approach is known to compromise protective immune surveillance of the brain. Unravelling the migratory paths of regulatory and pathogenic DC within the CNS may ultimately lead to the design of new therapeutic strategies able to selectively interfere with the recruitment of pathogenic DC to the CNS, while leaving host protective mechanisms intact.

GPR15+ T cells are Th17 like, increased in smokers and associated with multiple sclerosis

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.

Reassessing B cell contributions in multiple sclerosis

There is growing recognition that B cell contributions to normal immune responses extend well beyond their potential to become antibody-producing cells, including roles at the innate-adaptive interface and their potential to modulate the responses of other immune cells such as T cells and myeloid cells. These B cell functions can have both pathogenic and protective effects in the context of central nervous system (CNS) inflammation. Here, we review recent advances in the field of multiple sclerosis (MS), which has traditionally been viewed as primarily a T cell-mediated disease, and we consider antibody-dependent and, particularly, emerging antibody-independent functions of B cells that may be relevant in both the peripheral and CNS disease compartments.

Aging and lymphocyte changes by immunomodulatory therapies impact PML risk in multiple sclerosis patients

New potent immunomodulatory therapies for multiple sclerosis (MS) are associated with increased risk for progressive multifocal leukoencephalopathy (PML). It is unclear why a subset of treated patients develops PML, but patient age has emerged as an important risk factor. PML is caused by the JC virus and aging is associated with immune senescence, which increases susceptibility to infection. With the goal of improving PML risk stratification, we here describe the lymphocyte changes that occur with disease-modifying therapies (DMTs) associated with high or moderate risk toward PML in MS patients, how these changes compare to immune aging, and which measures best correlate with risk. We reviewed studies examining how these therapies alter patient immune profiles, which revealed the induction of changes to lymphocyte number and/or function that resemble immunosenescence. Therefore, the immunosuppressive activity of these MS DMTs may be enhanced in the context of an immune system that is already exhibiting features of senescence.

Understanding Progressive Multifocal Leukoencephalopathy Risk in Multiple Sclerosis Patients Treated with Immunomodulatory Therapies: A Bird's Eye View

The increased use of newer potent immunomodulatory therapies for multiple sclerosis (MS), including natalizumab, fingolimod, and dimethyl fumarate, has expanded the patient population at risk for developing progressive multifocal leukoencephalopathy (PML). These MS therapies shift the profile of lymphocytes within the central nervous system (CNS) leading to increased anti-inflammatory subsets and decreased immunosurveillance. Similar to MS, PML is a demyelinating disease of the CNS, but it is caused by the JC virus. The manifestation of PML requires the presence of an active, genetically rearranged form of the JC virus within CNS glial cells, coupled with the loss of appropriate JC virus-specific immune responses. The reliability of metrics used to predict risk for PML could be improved if all three components, i.e., viral genetic strain, localization, and host immune function, were taken into account. Advances in our understanding of the critical lymphocyte subpopulation changes induced by these MS therapies and ability to detect viral mutation and reactivation will facilitate efforts to develop these metrics.

EBI2 Expression and Function: Robust in Memory Lymphocytes and Increased by Natalizumab in Multiple Sclerosis

The interaction between oxysterols and the G protein-coupled receptor Epstein-Barr virus-induced gene 2 (EBI2) fine-tunes immune cell migration, a mechanism efficiently targeted by several disease-modifying treatments developed to treat multiple sclerosis (MS), such as natalizumab. We previously showed that memory CD4⁺ T lymphocytes migrate specifically in response to 7α,25-dihydroxycholesterol (7α,25-OHC) via EBI2 in the MS murine model experimental autoimmune encephalomyelitis. However, the EBI2 expression profile in human lymphocytes in both healthy and MS donors is unknown. Here, we characterize EBI2 biology in human lymphocytes. We observed that EBI2 is functionally expressed on memory CD4⁺ T cells and is enhanced under natalizumab treatment. These data suggest a significant role for EBI2 in human CD4⁺ T cell migration, notably in patients with MS. Better knowledge of EBI2 involvement in autoimmunity may therefore lead to an improved understanding of the physiopathology of MS.

Impaired T-cell migration to the CNS under fingolimod and dimethyl fumarate

Objective:

To evaluate the long-term effects of treatments used in MS on the T-cell trafficking profile.

Methods:

We enrolled 83 patients with MS under fingolimod (FTY), natalizumab (NTZ), dimethyl fumarate (DMF), or other disease-modifying treatments (DMTs). Blood was drawn before treatment onset and up to 36–48 months. The ex vivo expression of CNS-related integrins (α4β1 and α_L subunit of LFA-1) and the gut-related integrin (α4β7) was assessed using flow cytometry on CD4⁺ and CD8⁺ T cells. The adhesion profiles of CD3⁺ T cells to specific integrin ligands (vascular cell adhesion molecule-1 [VCAM-1], intercellular adhesion molecule-1 [ICAM-1], and mucosal vascular addressin cell adhesion molecule-1 [MAdCAM-1]) were measured in vitro before and after 12 and 36–48 months.

Results:

NTZ decreased the frequency of α4β1⁺ and α4β7⁺ integrin expressing T cells and the binding of these cells to VCAM-1 and MAdCAM-1, respectively. After 12 months, DMF induced a decreased frequency of α_L^highCD4⁺ T cells combined with reduced binding to ICAM-1. By contrast, with FTY, there was a doubling of the frequency of α4β1⁺ and α_L^high, but a decreased frequency of α4β7⁺ T cells. Strikingly, the binding of α4β1⁺, α4β7⁺, and to a lesser extent of α_L^high T cells to VCAM-1, MAdCAM-1, and ICAM-1, respectively, was decreased at month 12 under FTY treatment. The presence of manganese partially restored the binding of these T cells to VCAM-1 in vitro, suggesting that FTY interferes with integrin activation.

Conclusions:

In addition to NTZ, DMF and FTY but not other tested DMTs may also decrease T-cell–mediated immune surveillance of the CNS. Whether this mechanism may contribute to the onset of CNS opportunistic infections remains to be shown.

Aquaporin-4 antibodies in patients treated with natalizumab for suspected MS

Objective:

To evaluate (1) the frequency of aquaporin-4 antibody (AQP4-ab)-seropositive cases among patients treated with natalizumab (NAT) and previously diagnosed with MS (MS^NAT) in a nationwide cohort, (2) the clinical course of NAT-treated AQP4-ab–seropositive neuromyelitis optica spectrum disorder (NMOSD) patients (NMO^NAT), (3) AQP4-ab titers in NMO^NAT and AQP4-ab–seropositive NMOSD treated with other immunotherapies (NMO^IT), and (4) immune mechanisms influencing disease activity in NMO^NAT.

Methods:

MS^NAT serum samples were retrospectively screened with a cell-based assay for AQP4-IgG and titers determined by ELISA. The annualized relapse rate (ARR) and disability progression were assessed. Serum levels of proinflammatory cytokines (interleukin [IL]-1β, IL-4, IL-6, IL-8, IL-10, IL-17, IL-21, and interferon [IFN]-γ) and the chemokine CXCL-10 of NMO^NAT patients identified in this (n = 4) and a previous study (n = 5) were measured by cytometric bead array and ELISA.

Results:

Of the 1,183 MS^NAT patients (851 female, median 9 NAT infusions), only 4 (0.33%; 3 female, 1 male) had AQP4-IgG. Of these, 2 fulfilled the 2006 NMO criteria and all met the 2015 NMOSD criteria. The ARR was higher in NMO^NAT vs MS^NAT (p = 0.0182). All 4 NMO^NAT patients had relapses and 2 had an increase of disability. AQP4-ab titers were higher in NMO^NAT (n = 9) vs NMO^IT (n = 13; p = 0.0059). IL-8, IL-1β, and IFN-γ serum levels were significantly higher, and CXCL-10 was significantly lower in NMO^NAT vs NMO^IT.

Conclusions:

Misdiagnosis of NMOSD with MS is rare. NAT was not able to control disease activity in NMO^NAT patients, who had higher serum levels of AQP4-IgG and proinflammatory cytokines than patients with NMOSD treated with other immunotherapies.

Characterization of naïve, memory and effector T cells in progressive multiple sclerosis

We characterized naïve, central memory (CM), effector memory (EM) and terminally differentiated effector memory (TEMRA) CD4⁺ and CD8⁺ T cells and their expression of CD49d and CD26 in peripheral blood in patients with multiple sclerosis (MS) and healthy controls. CD26⁺ CD28⁺ CD4⁺ TEMRA T cells were increased in all subtypes of MS, and CD26⁺ CD28⁺ CD8⁺ TEMRA T cells were increased in relapsing-remitting and secondary progressive MS. Conversely, in progressive MS, CD49d⁺ CM T cells were decreased and natalizumab increased the circulating number of all six subsets but reduced the frequency of most subsets expressing CD49d and CD26.

Novel CD28 antagonist mPEG PV1-Fab' mitigates experimental autoimmune uveitis by suppressing CD4+ T lymphocyte activation and IFN-γ production

Autoimmune Uveitis is an important chronic inflammatory disease and a leading cause of impaired vision and blindness. This ocular autoimmune disorder is mainly mediated by T CD4⁺ lymphocytes poising a T_H1 phenotype. Costimulatory molecules are known to play an important role on T cell activation and therefore represent interesting therapeutical targets for autoimmune disorders. CD28 is the prototypical costimulatory molecule for T lymphocytes, and plays a crucial role in the initiation, and maintenance of immune responses. However, previous attempts to use this molecule in clinical practice achieved no success. Thus, we evaluated the efficacy of mPEG PV1-Fab’ (PV1), a novel selective CD28 antagonist monovalent Fab fragment in the treatment of Experimental Autoimmune Uveitis (EAU). Here, we showed that PV1 treatment decreases both average disease score and incidence of EAU. A decrease in the activation profile of both T CD4⁺ and T CD8⁺ eye-infiltrating lymphocytes was evidenced. In the periphery, T CD4⁺ cells from PV1-treated mice also showed a decrease in their activation status, with reduced expression of CD69, CD25, and PD-1 molecules. This suppression was not dependent on Treg cells, as both their frequency and absolute number were lower in PV1-treated mice. In addition, frequency of CD4⁺IFN-γ⁺ T cells was significantly lower in PV1-treated group, but not of IL-17-producing T cells. Moreover, after specific restimulation, PV1 blockade selectively blocked IFN-γ production by CD4⁺ lymphocytes Taken together, our data suggest that mPEG PV1-Fab’ acts mainly on IFN-γ-producing CD4⁺ T cells and emphasize that this specific CD28 blockade strategy is a potential specific and alternative tool for the treatment of autoimmune disorders in the eye.

OX40, OX40L and Autoimmunity: a Comprehensive Review

The tumour necrosis factor receptor OX40 (CD134) is activated by its cognate ligand OX40L (CD134L, CD252) and functions as a T cell co-stimulatory molecule. OX40-OX40L interactions have been proposed as a potential therapeutic target for treating autoimmunity. OX40 is expressed on activated T cells, and in the mouse at rest on regulatory T cells (Treg). OX40L is found on antigen-presenting cells, activated T cells and others including lymphoid tissue inducer cells, some endothelia and mast cells. Expression of both molecules is increased after antigen presentation occurs and also in response to multiple other pro-inflammatory factors including CD28 ligation, CD40L ligation and interferon-gamma signaling. Their interactions promote T cell survival, promote an effector T cell phenotype, promote T cell memory, tend to reduce regulatory function, increase effector cytokine production and enhance cell mobility. In some circumstances, OX40 agonism may be associated with increased tolerance, although timing with respect to antigenic stimulus is important. Further, recent work has suggested that OX40L blockade may be more effective than OX40 blockade in reducing autoimmunity. This article reviews the expression of OX40 and OX40L in health, the effects of their interactions and insights from their under- or over-expression. We then review OX40 and OX40L expression in human autoimmune disease, identified associations of variations in their genes (TNFRSF4 and TNFSF4, respectively) with autoimmunity, and data from animal models of human diseases. A rationale for blocking OX40-OX40L interaction in human autoimmunity is then presented along with commentary on the one trial of OX40L blockade in human disease conducted to date. Finally, we discuss potential problems with clinical use of OX40-OX40L directed pharmacotherapy.

Soluble serum VCAM-1, whole blood mRNA expression and treatment response in natalizumab-treated multiple sclerosis

BACKGROUND

Natalizumab reduces disease activity in multiple sclerosis (MS). Natalizumab binds to the very late antigen-4 and inhibits vascular cell adhesion molecule-1 (VCAM-1)-mediated transmigration of immune cells across the blood-brain-barrier. This is associated with decreased serum concentrations of soluble (s)VCAM-1 and an altered composition of immune cell-subsets in the blood.

OBJECTIVE

We aimed to examine if sVCAM-1 serum concentrations and whole blood mRNA expression levels of immune activation biomarkers is associated with disease activity in natalizumab-treated MS-patients.

METHODS

sVCAM-1 serum concentrations and whole blood mRNA expression were measured in blood samples from untreated RRMS-patients and from two independent groups of natalizumab-treated patients.

RESULTS

sVCAM-1 serum concentrations and whole blood expression of HLX1 and IL1B mRNA were lower, whereas expression of EBI3 mRNA was higher in natalizumab-treated MS-patients. Five genes were differentially expressed in clinically unstable natalizumab-treated MS-patients in the discovery but not in the validation group.

CONCLUSION

Decreased serum concentrations of sVCAM-1 and altered whole blood mRNA expression levels of a panel of immunomarkers, associated with natalizumab-treatment, are not sensitive markers of MS disease activity. However, decreased expression of pro-inflammatory HLX1 and IL1B and increased expression of immunoregulatory EBI3 may indicate a less pathogenic immune activation status in natalizumab-treated MS.

Natalizumab Affects T-Cell Phenotype in Multiple Sclerosis: Implications for JCV Reactivation

The anti-CD49d monoclonal antibody natalizumab is currently an effective therapy against the relapsing-remitting form of multiple sclerosis (RRMS). Natalizumab therapeutic efficacy is limited by the reactivation of the John Cunningham polyomavirus (JCV) and development of progressive multifocal leukoencephalopathy (PML). To correlate natalizumab-induced phenotypic modifications of peripheral blood T-lymphocytes with JCV reactivation, JCV-specific antibodies (serum), JCV-DNA (blood and urine), CD49d expression and relative abundance of peripheral blood T-lymphocyte subsets were longitudinally assessed in 26 natalizumab-treated RRMS patients. Statistical analyses were performed using GraphPad Prism and R. Natalizumab treatment reduced CD49d expression on memory and effector subsets of peripheral blood T-lymphocytes. Moreover, accumulation of peripheral blood CD8⁺ memory and effector cells was observed after 12 and 24 months of treatment. CD4⁺ and CD8⁺ T-lymphocyte immune-activation was increased after 24 months of treatment. Higher percentages of CD8⁺ effectors were observed in subjects with detectable JCV-DNA. Natalizumab reduces CD49d expression on CD8⁺ T-lymphocyte memory and effector subsets, limiting their migration to the central nervous system and determining their accumulation in peripheral blood. Impairment of central nervous system immune surveillance and reactivation of latent JCV, can explain the increased risk of PML development in natalizumab-treated RRMS subjects.

Role of IL-17-producing lymphocytes in severity of multiple sclerosis upon natalizumab treatment

OBJECTIVE

Natalizumab is known to prevent T-helper cells entering the central nervous system (CNS). We hypothesize that more pathogenic T-helper cells are present outside the CNS and a possible relationship to disease severity.

METHODS

Characterization and enrichment of human CD4+IL-17+ cells were performed ex vivo using peripheral blood mononuclear cells from natalizumab-treated relapsing-remitting multiple sclerosis (RRMS) patients ( n = 33), untreated RRMS patients ( n = 13), and healthy controls ( n = 33). Magnetic resonance imaging (MRI) scans were performed routinely for patients.

RESULTS

Lymphocytes were elevated in peripheral blood of natalizumab-treated patients compared to untreated patients and healthy controls. Whereas group comparison for CD4+IL-17+ numbers also differed, CD4+IFN-γ+ and CD4+IL-22+ counts were not increased. CD4+IL-17+ cells not only expressed but also secreted IL-17. In natalizumab-treated patients, IL-17+ cell frequency was found to correlate with T1-hypointense lesions, but was not an indicator for rebound activity after treatment discontinuation, except in one patient who experienced a fulminant rebound, and interestingly, in whom the highest IL-17+ cell levels were observed.

CONCLUSION

Increased lymphocytes and CD4+IL-17+ cells in the blood of RRMS patients receiving natalizumab corroborate the drug's mechanism of action, that is, blocking transmigration to CNS. Correlation between IL-17-expressing lymphocytes and T1-hypointense lesions underlines the important role of these cells in the disease pathology.

New insights into the pharmacokinetics and pharmacodynamics of natalizumab treatment for patients with multiple sclerosis, obtained from clinical and in vitro studies

BACKGROUND

The monoclonal antibody natalizumab (NAT) inhibits the migration of lymphocytes throughout the blood-brain barrier by blocking very late antigen (VLA)-4 interactions, thereby reducing inflammatory central nervous system (CNS) activity in patients with multiple sclerosis (MS). We evaluated the effects of different NAT treatment regimens.

METHODS

We developed and optimised a NAT assay to measure free NAT, cell-bound NAT and VLA-4 expression levels in blood and cerebrospinal fluid (CSF) of patients using standard and prolonged treatment intervals and after the cessation of therapy.

RESULTS

In paired CSF and blood samples of NAT-treated MS patients, NAT concentrations in CSF were approximately 100-fold lower than those in serum. Cell-bound NAT and mean VLA-4 expression levels in CSF were comparable with those in blood. After the cessation of therapy, the kinetics of free NAT, cell-bound NAT and VLA-4 expression levels differed. Prolonged intervals greater than 4 weeks between infusions caused a gradual reduction of free and cell-bound NAT concentrations. Sera from patients with and without NAT-neutralising antibodies could be identified in a blinded assessment. The NAT-neutralising antibodies removed NAT from the cell surface in vivo and in vitro. Intercellular NAT exchange was detected in vitro.

CONCLUSIONS

Incorporating assays to measure free and cell-bound NAT into clinical practice can help to determine the optimal individual NAT dosing regimen for patients with MS.

Exploring potential mechanisms of action of natalizumab in secondary progressive multiple sclerosis

Multiple sclerosis (MS) is a common and chronic central nervous system (CNS) demyelinating disease and a leading cause of permanent disability. Patients most often present with a relapsing-remitting disease course, typically progressing over time to a phase of relentless advancement in secondary progressive MS (SPMS), for which approved disease-modifying therapies are limited. In this review, we summarize the pathophysiological mechanisms involved in the development of SPMS and the rationale and clinical potential for natalizumab, which is currently approved for the treatment of relapsing forms of MS, to exert beneficial effects in reducing disease progression unrelated to relapses in SPMS. In both forms of MS, active brain-tissue injury is associated with inflammation; but in SPMS, the inflammatory response occurs at least partly behind the blood-brain barrier and is followed by a cascade of events, including persistent microglial activation that may lead to chronic demyelination and neurodegeneration associated with irreversible disability. In patients with relapsing forms of MS, natalizumab therapy is known to significantly reduce intrathecal inflammatory responses which results in reductions in brain lesions and brain atrophy as well as beneficial effects on clinical measures, such as reduced frequency and severity of relapse and reduced accumulation of disability. Natalizumab treatment also reduces levels of cerebrospinal fluid chemokines and other biomarkers of intrathecal inflammation, axonal damage and demyelination, and has demonstrated the ability to reduce innate immune activation and intrathecal immunoglobulin synthesis in patients with MS. The efficacy of natalizumab therapy in SPMS is currently being investigated in a randomized, double-blind, placebo-controlled trial.

Natalizumab treatment reduces L-selectin (CD62L) in CD4+ T cells

Background

The purpose of this research was to validate the low expression of L-selectin (CD62L) in natalizumab (NTZ)-treated patients. CD62L is involved in rolling and transmigration of leukocyte cells. A correlation between CD62LCD4⁺ T cells low expression and progressive multifocal leukoencephalopathy (PML) development has been suggested in multiple sclerosis (MS) patients treated with NTZ.

Methods

We performed a flow cytometric analysis on peripheral blood mononuclear cells (PBMC); we collected from 23 healthy donors and 225 MS patients: untreated (n = 19) or treated with NTZ (n = 113), interferon-beta (n = 26), glatiramer acetate (n = 26), fingolimod (n = 23) and rituximab (n = 18). We have also analysed two PML/IRIS (immune reconstitution inflammatory syndrome) patients and four longitudinal samples of a NTZ-treated patients before and during the development of a clinical asymptomatic magnetic resonance imaging (MRI) lesion confirmed as PML by cerebrospinal fluid (CSF) examination. Thirty-five NTZ-treated patients were studied longitudinally with three samples taken 4 months apart.

Results

The NTZ-treated patients showed a lower percentage of CD62L (33.68 %, n = 113) than first-line treated patients (44.24 %, n = 52, p = 0.0004). NTZ effect was already clear during the first year of treatment (34.68 %; p = 0.0184); it persisted in the following years and disappeared after drug withdrawal (44.08 %). Three percent of longitudinally analysed patients showed a percentage of CD62LCD4⁺ T cells under a hypothetical threshold and one patient with asymptomatic PML belongs to a group which expressed low percentage of CD62LCD4⁺ T cells.

Conclusions

Our research confirms that NTZ has a specific effect on CD62LCD4⁺ T cells consisting in decreasing of the number of positive cells. The low level of CD62L found in a clinically asymptomatic PML patient strengthens its potential usefulness as a biomarker of high PML risk in NTZ-treated patients. A larger study is required to better confirm the data.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-015-0365-x) contains supplementary material, which is available to authorized users.

Natalizumab treatment for multiple sclerosis: updates and considerations for safer treatment in JCV positive patients

Natalizumab is currently one of the best options for treatment of patients with Multiple Sclerosis who have failed traditional prior therapies. However, prolonged use, prior immunosuppressive therapy and anti-JCV antibody status have been associated with increased risk of developing progressive multifocal leukoencephalopathy (PML). The evaluation of these conditions has been used to estimate risks of PML in these patients, and distinct (sometimes extreme) approaches are used to avoid the PML onset. At this time, the biggest issue facing the use of Natalizumab is how to get a balance between the risks and the benefits of the treatment. Hence, strategies for monitor JCV-positive patients undergoing Natalizumab treatment are deeply necessary. To illustrate it, we monitored JCV/DNA in blood and urine of a patient receiving Natalizumab for 12 months. We also bring to discussion the effectiveness of the current methods used for risk evaluation, and the real implications of viral reactivation.

Effect of natalizumab treatment on circulating plasmacytoid dendritic cells: a cross-sectional observational study in patients with multiple sclerosis

Objectives

Dendritic cells (DCs) serve a critical role both in promoting and inhibiting adaptive immunity. The goal of this study was to investigate the effect of natalizumab (NTZ) treatment on DC numbers, phenotype, and function in patients with multiple sclerosis (MS).

Methods

Frequency and phenotype of myeloid and plasmacytoid DCs (MDCs and PDCs, respectively) were analyzed in blood from two separate cohorts of untreated, interferon-treated, or NTZ-treated MS patients. In addition, PDCs were stimulated with CpG-containing oligonucleotides or co-cultured with homologous T cells in the presence or absence of NTZ in vitro to determine functional effects of NTZ treatment.

Results

We observed that NTZ treatment was associated with a 25–50% reduction in PDC frequency in peripheral blood as compared to untreated MS patients, while the frequency of MDCs was unchanged. PDCs in NTZ-treated patients displayed a mature, activated phenotype with increased expression of HLA-DR, TLR9, CCR7, IL-6 and IL-12. In contrast, in vitro treatment with NTZ did not increase markers of PDC activation or their ability to induce T cell differentiation.

Conclusion

Our study shows that NTZ treatment is associated with a reduced frequency of PDCs in the peripheral circulation, but that PDCs in NTZ-treated individuals display an activated phenotype. Taken together the data suggests that transmigration of activated PDCs is preferentially affected by blockade of integrin α4 leading to an increased frequency of activated PDCs in blood.

Natalizumab: a review of its use in the management of relapsing-remitting multiple sclerosis

Natalizumab (Tysabri®) is a humanized monoclonal antibody against the α4 chain of integrins and was the first targeted therapy to be approved for the treatment of relapsing-remitting multiple sclerosis (RRMS). Natalizumab acts as a selective adhesion molecule antagonist, which binds very late antigen (VLA)-4 and inhibits the translocation of activated VLA-4-expressing leukocytes across the blood-brain barrier into the CNS. In a pivotal phase III clinical trial, natalizumab 300 mg intravenously every 4 weeks for 2 years in adults with RRMS significantly reduced the annualized relapse rate and the risk of sustained progression of disability compared with placebo, as well as significantly increasing the proportion of relapse-free patients at 1 and 2 years. Natalizumab also significantly reduced the number of T2-hyperintense, gadolinium-enhancing and T1-hypointense lesions on magnetic resonance imaging, and significantly reduced the volume of T2-hyperintense and T1-hypointense lesions compared with placebo. Natalizumab recipients generally experienced improved health-related quality of life at 1-2 years. Natalizumab was generally well tolerated in pivotal trials. The only adverse events that were more frequent with natalizumab monotherapy than with placebo were fatigue and allergic reactions. The main safety and tolerability issue with natalizumab is the incidence of progressive multifocal leukoencephalopathy (PML). As long as the risk of PML is managed effectively, natalizumab is a valuable therapeutic option for adults with highly active relapsing forms of multiple sclerosis.

A changing treatment landscape for multiple sclerosis: challenges and opportunities

Multiple sclerosis (MS) is primarily an autoimmune disease of the central nervous system, but also encompasses prominent neurodegenerative aspects. A significant proportion of MS patients will develop neurological disability over time and up until recently treatment options have been limited. However, MS treatment is now at a stage of rapid progress, with several new drugs that have reached the market or will be launched in the near future. This provides new opportunities for individualized treatment, but also creates new challenges regarding monitoring of disease activity, long-term safety issues and efficacy, not least in patients with progressive disease.

Teriflunomide and its mechanism of action in multiple sclerosis

Treatment of multiple sclerosis (MS) is challenging: disease-modifying treatments (DMTs) must both limit unwanted immune responses associated with disease initiation and propagation (as T and B lymphocytes are critical cellular mediators in the pathophysiology of relapsing MS), and also have minimal adverse impact on normal protective immune responses. In this review, we summarize key preclinical and clinical data relating to the proposed mechanism of action of the recently approved DMT teriflunomide in MS. Teriflunomide selectively and reversibly inhibits dihydro-orotate dehydrogenase, a key mitochondrial enzyme in the de novo pyrimidine synthesis pathway, leading to a reduction in proliferation of activated T and B lymphocytes without causing cell death. Results from animal experiments modelling the immune activation implicated in MS demonstrate reductions in disease symptoms with teriflunomide treatment, accompanied by reduced central nervous system lymphocyte infiltration, reduced axonal loss, and preserved neurological functioning. In agreement with the results obtained in these model systems, phase 3 clinical trials of teriflunomide in patients with MS have consistently shown that teriflunomide provides a therapeutic benefit, and importantly, does not cause clinical immune suppression. Taken together, these data demonstrate how teriflunomide acts as a selective immune therapy for patients with MS.

Increased B cell and cytotoxic NK cell proportions and increased T cell responsiveness in blood of natalizumab-treated multiple sclerosis patients

Background

Changes in the blood lymphocyte composition probably both mediate and reflect the effects of natalizumab treatment in multiple sclerosis, with implications for treatment benefits and risks.

Methods

A broad panel of markers for lymphocyte populations, including states of activation and co-stimulation, as well as functional T cell responses to recall antigens and mitogens, were assessed by flow cytometry in 40 patients with relapsing multiple sclerosis before and after one-year natalizumab treatment.

Results

Absolute numbers of all major lymphocyte populations increased after treatment, most markedly for NK and B cells. The fraction of both memory and presumed regulatory B cell subsets increased, as did CD3^-CD56^dim cytotoxic NK cells, whereas CD3^-CD56^bright regulatory NK cells decreased. The increase in cell numbers was further associated with a restored T cell responsiveness to recall antigens and mitogens in functional assays.

Conclusions

Our data confirms that natalizumab treatment increases the number of lymphocytes in blood, likely mirroring the expression of VLA-4 being highest on NK and B cells. This finding supports reduction of lymphocyte extravasation as a main mode of action, although the differential effects on subpopulation composition suggests that cell-signalling may also be affected. The systemic increase in T cell responsiveness reflects the increase in numbers, and while augmenting anti-infectious responses systemically, localized responses may become correspondingly decreased.

Immunological and clinical consequences of splenectomy in a multiple sclerosis patient treated with natalizumab

OBJECTIVE

Here we report a case of a splenectomized white woman with natalizumab-associated progressive multifocal leukoencephalopathy (PML), occurring as early as after 11 infusions and provide blood fluorescence-activated cell sorting (FACS) analyses before and after natalizumab treatment.

DESIGN

This is a report of a single case with immunological studies.

METHODS

Methods comprised neurologic examination, magnetic resonance imaging, and cerebrospinal fluid (CSF) studies as well as immune cell FACS analyses from blood.

RESULTS

Diagnosis of PML was established after positive John Cunningham virus (JCV) DNA was detected in the CSF. An immune reconstitution inflammatory syndrome was treated with repeated cycles of steroid pulses and intravenous immunoglobulins. Reduced numbers of memory B cells, which might play an important role in antiviral immune response, were detected in the blood. Moreover the percentage of CD19+ B cells was elevated in our post-splenectomy patient as compared to a control cohort of multiple sclerosis (MS) patients under natalizumab therapy.

CONCLUSION

Splenectomy may increase the risk for the development of natalizumab-associated PML via effects on the B cell compartment. It may be regarded as a risk factor in MS patients independent from the duration of disease.

Evaluation of circulating osteopontin levels in an unselected cohort of patients with multiple sclerosis: relevance for biomarker development

BACKGROUND

Osteopontin (OPN) is a pleiotropic protein with important roles in inflammation and immunity that has been suggested as a candidate biomarker for disease activity in multiple sclerosis (MS).

OBJECTIVE

We evaluated plasma levels of OPN in an unselected cohort of MS patients, to determine its potential as a biomarker for disease subtype and/or disease activity in a regular clinical setting.

METHODS

We analyzed OPN plasma levels in 492 consecutive MS patients, using a commercial enzyme-linked immunosorbent assay (ELISA).

RESULTS

OPN levels were higher in relapsing-remitting and secondary progressive MS, compared to healthy controls. Treatment with natalizumab or glatiramer acetate was associated with lower OPN levels. There was no significant association between the OPN levels and disease activity, as measured by clinical or radiological criteria. One-third of patients with high OPN levels had concurrent disorders that may also be associated with increased OPN expression, and which may mask a modest effect of MS disease activity on OPN levels.

CONCLUSION

Our data do not support a role for circulating OPN levels as a biomarker for disease activity in a heterogeneous clinical setting, but does not rule out a potential role in the cerebrospinal fluid, in a controlled setting such as a clinical trial, or in concert with other biomarkers.