Distinct T cell signatures define subsets of patients with multiple sclerosis

Hallmarks of spinal cord pathology in multiple sclerosis

A disparity exists between spinal cord and brain involvement in multiple sclerosis (MS), each independently contributing to disability. Underlying differences between brain and cord are not just anatomical in nature (volume, white/grey matter organization, vascularization), but also in barrier functions (differences in function and composition of the blood-spinal cord barrier compared to blood-brain barrier) and possibly in repair mechanisms. Also, immunological phenotypes seem to influence localization of inflammatory activity. Whereas the brain has gained a lot of attention in MS research, the spinal cord lags behind. Advanced imaging techniques and biomarkers are improving and providing us with tools to uncover the mechanisms of spinal cord pathology in MS. In the present review, we elaborate on the underlying anatomical and physiological factors driving differences between brain and cord involvement in MS and review current literature on pathophysiology of spinal cord involvement in MS and the observed differences to brain involvement.

Effect of disease-modifying treatment on spinal cord lesion formation in multiple sclerosis: A retrospective observational study

BACKGROUND

Spinal cord lesions in multiple sclerosis (MS) are an important contributor to disability. Knowledge on the effect of disease-modifying treatment (DMT) on spinal lesion formation in MS is sparse, as cord outcome measures are seldom included in MS treatment trials. We aim to investigate whether intermediate- or high-efficacy DMTs (i/hDMT) can reduce spinal lesion formation, compared with low-efficacy DMTs (lDMT) and/or no treatment.

METHODS

Relapse-onset MS patients with ≥2 spinal MRIs (interval >3 months and <10 years) were retrospectively identified. The i/hDMT-group was defined as patients who were treated with i/hDMTs during ≥90% of spinal MRI follow-up time. Controls received lDMTs and/or no treatment ≥90% of follow-up duration. In a secondary analysis, only patients using lDMT for ≥90% of follow-up were considered controls. Patients were matched using propensity-scores. Cox proportional hazards models were used to estimate the risk of new spinal lesions.

RESULTS

323 patients had ≥2 spinal cord MRIs. 49 satisfied i/hDMT and 168 control group criteria. 34 i/hDMT patients were matched to 83 controls. Patients in the i/hDMT-group were significantly less likely to develop new cord lesions at follow-up (HR 0.29 [0.12-0.75], p = 0.01). When the i/hDMT-group was matched to only controls using lDMT ≥90% of follow-up time (n = 17 and n = 25, respectively), there was no statistically significant difference (HR 1.01 [0.19-5.24], p = 0.99).

CONCLUSION

Treatment with intermediate- or high-efficacy DMTs reduces the risk of new spinal cord lesions compared with matched patients receiving no treatment and/or lDMTs. No conclusions could be drawn on whether i/hDMTs provide a larger risk reduction compared to only lDMTs (control group receiving lDMTs ≥90% of follow-up time).

Pathophysiology of myelin oligodendrocyte glycoprotein antibody disease

Myelin Oligodendrocyte Glycoprotein Antibody Disease (MOGAD) is a spectrum of diseases, including optic neuritis, transverse myelitis, acute disseminated encephalomyelitis, and cerebral cortical encephalitis. In addition to distinct clinical, radiological, and immunological features, the infectious prodrome is more commonly reported in MOGAD (37-70%) than NMOSD (15-35%). Interestingly, pediatric MOGAD is not more aggressive than adult-onset MOGAD, unlike in multiple sclerosis (MS), where annualized relapse rates are three times higher in pediatric-onset MS. MOGAD pathophysiology is driven by acute attacks during which T cells and MOG antibodies cross blood brain barrier (BBB). MOGAD lesions show a perivenous confluent pattern around the small veins, lacking the radiological central vein sign. Initial activation of T cells in the periphery is followed by reactivation in the subarachnoid/perivascular spaces by MOG-laden antigen-presenting cells and inflammatory CSF milieu, which enables T cells to infiltrate CNS parenchyma. CD4+ T cells, unlike CD8+ T cells in MS, are the dominant T cell type found in lesion histology. Granulocytes, macrophages/microglia, and activated complement are also found in the lesions, which could contribute to demyelination during acute relapses. MOG antibodies potentially contribute to pathology by opsonizing MOG, complement activation, and antibody-dependent cellular cytotoxicity. Stimulation of peripheral MOG-specific B cells through TLR stimulation or T follicular helper cells might help differentiate MOG antibody-producing plasma cells in the peripheral blood. Neuroinflammatory biomarkers (such as MBP, sNFL, GFAP, Tau) in MOGAD support that most axonal damage happens in the initial attack, whereas relapses are associated with increased myelin damage.

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.

Made to Measure: Patient-Tailored Treatment of Multiple Sclerosis Using Cell-Based Therapies

Currently, there is still no cure for multiple sclerosis (MS), which is an autoimmune and neurodegenerative disease of the central nervous system. Treatment options predominantly consist of drugs that affect adaptive immunity and lead to a reduction of the inflammatory disease activity. A broad range of possible cell-based therapeutic options are being explored in the treatment of autoimmune diseases, including MS. This review aims to provide an overview of recent and future advances in the development of cell-based treatment options for the induction of tolerance in MS. Here, we will focus on haematopoietic stem cells, mesenchymal stromal cells, regulatory T cells and dendritic cells. We will also focus on less familiar cell types that are used in cell therapy, including B cells, natural killer cells and peripheral blood mononuclear cells. We will address key issues regarding the depicted therapies and highlight the major challenges that lie ahead to successfully reverse autoimmune diseases, such as MS, while minimising the side effects. Although cell-based therapies are well known and used in the treatment of several cancers, cell-based treatment options hold promise for the future treatment of autoimmune diseases in general, and MS in particular.

The hedgehog pathway suppresses neuropathogenesis in CD4 T cell-driven inflammation

The concerted actions of the CNS and the immune system are essential to coordinating the outcome of neuroinflammatory responses. Yet, the precise mechanisms involved in this crosstalk and their contribution to the pathophysiology of neuroinflammatory diseases largely elude us. Here, we show that the CNS-endogenous hedgehog pathway, a signal triggered as part of the host response during the inflammatory phase of multiple sclerosis and experimental autoimmune encephalomyelitis, attenuates the pathogenicity of human and mouse effector CD4 T cells by regulating their production of inflammatory cytokines. Using a murine genetic model, in which the hedgehog signalling is compromised in CD4 T cells, we show that the hedgehog pathway acts on CD4 T cells to suppress the pathogenic hallmarks of autoimmune neuroinflammation, including demyelination and axonal damage, and thus mitigates the development of experimental autoimmune encephalomyelitis. Impairment of hedgehog signalling in CD4 T cells exacerbates brain-brainstem-cerebellum inflammation and leads to the development of atypical disease. Moreover, we present evidence that hedgehog signalling regulates the pathogenic profile of CD4 T cells by limiting their production of the inflammatory cytokines granulocyte-macrophage colony-stimulating factor and interferon-γ and by antagonizing their inflammatory program at the transcriptome level. Likewise, hedgehog signalling attenuates the inflammatory phenotype of human CD4 memory T cells. From a therapeutic point of view, our study underlines the potential of harnessing the hedgehog pathway to counteract ongoing excessive CNS inflammation, as systemic administration of a hedgehog agonist after disease onset effectively halts disease progression and significantly reduces neuroinflammation and the underlying neuropathology. We thus unveil a previously unrecognized role for the hedgehog pathway in regulating pathogenic inflammation within the CNS and propose to exploit its ability to modulate this neuroimmune network as a strategy to limit the progression of ongoing neuroinflammation.

Combining miR-23b exposure with mesenchymal stem cell transplantation enhances therapeutic effects on EAE

Bone marrow mesenchymal stem cells (BMSCs) have the immuno-modulatory capacity to ameliorate autoimmune diseases, such as multiple schlerosis (MS), systemic lupus erythematosus and rheumatoid arthritis. However, BMSC-mediated immunosuppression can be challenging to achieve. The efficacy of BMSC transplantation may be augmented by an adjuvant therapy. Here, we demonstrated that treatment of mice with experimental autoimmune encephalomyelitis (EAE), a model of MS, with BMSCs over-expressing microRNA (miR)-23b provided better synergistic and longer-term therapeutic effects than treatment with traditional BMSCs. Over-expression of miR-23b enhanced the ability of BMSCs to inhibit differentiation of Th17 cells and reduced IL-17 secretion. Compared to traditional BMSCs, the miR-23b over-expressing BMSCs (miR23b-BMSCs) exhibited enhanced secretion of tumor growth factor beta 1 (TGF-β₁), a cytokine that promotes the differentiation of regulatory T (Treg) cells. Pathologically, miR23b-BMSC transplantation delayed EAE progression, apparently by reducing the Th17/Treg cell ratio and inhibiting inflammatory cell infiltration across the blood-brain barrier, and thus slowing spinal cord demyelination. These results may lead to better utility of BMSCs as a treatment for autoimmune diseases.

Cytokines and transcription factors in the differentiation of CD4+ T helper cell subsets and induction of tissue inflammation and autoimmunity

CD4⁺T helper (Th) cells are critical in homeostasis and host defense but are also central to the development of various autoimmune diseases if they become dysregulated. Specifically, pathogenic Th1 and Th17 cells contribute to autoimmune inflammation whereas Treg and Tr1 cells are important for maintaining immune tolerance and resolution of inflammation, respectively. Cytokines trigger signaling pathways in naive T cells that induce lineage-defining transcription factors that direct their differentiation into the distinct T helper cell subsets. It has become clear that the differentiation of T helper cells is not only influenced by the cytokine milieu but also by their metabolic state, cues from the microbiota and the tissue they reside in. A comprehensive understanding how these various stimuli contribute to T helper cell differentiation and phenotype could potentially provide novel ways for therapeutic intervention in autoimmunity and tissue inflammation.

Mechanisms of M2 Macrophage-Derived Exosomal Long Non-coding RNA PVT1 in Regulating Th17 Cell Response in Experimental Autoimmune Encephalomyelitisa

Long non-coding RNA (lncRNA) is pivotal for multiple sclerosis (MS), but the potential mechanism of lncRNA PVT1 in MS animal model, experimental autoimmune encephalomyelitis (EAE) still remains unclear. In this study, macrophages were firstly isolated and induced to polarize into M2 macrophages. M2 macrophage-derived exosomes (M2-exos) were extracted and identified, and EAE mouse model was established and treated with M2-exos. The effect of M2-exos on EAE mice was evaluated by clinical scores. The proportion of Treg and Th17 cells in spinal cord cells and splenocytes, and levels of inflammatory factors were measured. The targeting relationships among PVT1, miR-21-5p, and SOCS5 were verified. The expression of JAKs/STAT3 pathway-related proteins was measured. After M2-exo treatment, the clinical score of EAE mice decreased, and demyelination and inflammatory infiltration improved; Th17 cells decreased, Treg cells increased, and the levels of inflammatory factors decreased significantly. SOCS5 and PVT1 were downregulated and miR-21-5p was upregulated in EAE mice. PVT1 could sponge miR-21-5p to regulate SOCS5. SOCS5 alleviated EAE symptoms by repressing the JAKs/STAT3 pathway. Together, M2-exos-carried lncRNA PVT1 sponged miR-21-5p to upregulate SOCS5 and inactivate the JAKs/STAT3 pathway, thus reducing inflammation and protecting EAE mice. This study may offer novel treatments for MS.

Th17 cells increase in RRMS as well as in SPMS, whereas various other phenotypes of Th17 increase in RRMS only

Background

The nature and extent of inflammation seen in multiple sclerosis (MS) varies throughout the course of the disease. Changes seen in CD4+ T-helper cells in relapsing–remitting (RR) MS and secondary progressive (SP) MS might differ qualitatively and/or quantitatively.

Objective

The objective of this paper is to study the frequencies of all major CD4+ T-helper subtypes – Th17, Th22 and Th1 lineage cells – in relapse, remission and secondary progression alongside CCR6 status, a chemokine receptor involved in migration of these cells into the central nervous system.

Methods

We compared 100 patients (50 RRMS and 50 SPMS) and 50 healthy volunteers and performed flow cytometric analysis of lymphocytes in blood samples.

Results

We demonstrated raised frequencies of various cell types along the Th17 axis; Th17, Th17.1 (IL-17+ interferon gamma+) and dual IL-17+ IL-22+ cells in RRMS. Th22 and CCR6+ Th1 cells (nonclassical Th1) were also increased in RRMS. All these cells were CCR6+. Only Th17 frequencies were elevated in SPMS.

Conclusions

Increased frequencies of Th17 cells are implicated both in RRMS and SPMS. The CCR6 pathway includes Th17, Th22 and Th1 nonclassical cells, of which Th22 and Th1 cells represent the greatest subsets in MS.

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.

Stem Cell-Derived Exosomes as Nanotherapeutics for Autoimmune and Neurodegenerative Disorders

To dissect therapeutic mechanisms of transplanted stem cells and develop exosome-based nanotherapeutics in treating autoimmune and neurodegenerative diseases, we assessed the effect of exosomes secreted from human mesenchymal stem cells (MSCs) in treating multiple sclerosis using an experimental autoimmune encephalomyelitis (EAE) mouse model. We found that intravenous administration of exosomes produced by MSCs stimulated by IFNγ (IFNγ-Exo) (i) reduced the mean clinical score of EAE mice compared to PBS control, (ii) reduced demyelination, (iii) decreased neuroinflammation, and (iv) upregulated the number of CD4+CD25+FOXP3+ regulatory T cells (Tregs) within the spinal cords of EAE mice. Co-culture of IFNγ-Exo with activated peripheral blood mononuclear cells (PBMCs) cells in vitro reduced PBMC proliferation and levels of pro-inflammatory Th1 and Th17 cytokines including IL-6, IL-12p70, IL-17AF, and IL-22 yet increased levels of immunosuppressive cytokine indoleamine 2,3-dioxygenase. IFNγ-Exo could also induce Tregs in vitro in a murine splenocyte culture, likely mediated by a third-party accessory cell type. Further, IFNγ-Exo characterization by deep RNA sequencing suggested that IFNγ-Exo contains anti-inflammatory RNAs, where their inactivation partially hindered the exosomes potential to induce Tregs. Furthermore, we found that IFNγ-Exo harbors multiple anti-inflammatory and neuroprotective proteins. These results not only shed light on stem cell therapeutic mechanisms but also provide evidence that MSC-derived exosomes can potentially serve as cell-free therapies in creating a tolerogenic immune response to treat autoimmune and central nervous system disorders.

The Diversity of Encephalitogenic CD4+ T Cells in Multiple Sclerosis and Its Animal Models

Autoreactive CD4+ T cells, which target antigens in central nervous system (CNS) myelin, are widely believed to play a critical role in the pathogenesis of multiple sclerosis (MS) in concert with other immune effectors. This theory is supported by data from animal model experiments, genome-wide association studies, and immune profiles of individuals with MS. Furthermore, disease modifying agents that target lymphocytes significantly reduce the rate of MS clinical exacerbations. However, the properties of myelin-reactive CD4+ T cells that are critical for their pathogenic activities are not understood completely. This article reviews the literature on encephalitogenic CD4+ T cells, with an emphasis on T-helper (Th) lineage and cytokine production. An increased understanding of the spectrum of encephalitogenic T cells and how they differ from protective subsets is necessary for the development of the next generation of more effective and safer immunomodulatory therapies customized for individuals with MS and related disorders.

Gut Microbiota Confers Resistance of Albino Oxford Rats to the Induction of Experimental Autoimmune Encephalomyelitis

Albino Oxford (AO) rats are extremely resistant to induction of experimental autoimmune encephalomyelitis (EAE). EAE is an animal model of multiple sclerosis, a chronic inflammatory disease of the central nervous system (CNS), with established autoimmune pathogenesis. The autoimmune response against the antigens of the CNS is initiated in the peripheral lymphoid tissues after immunization of AO rats with CNS antigens. Subsequently, limited infiltration of the CNS occurs, yet without clinical sequels. It has recently become increasingly appreciated that gut-associated lymphoid tissues (GALT) and gut microbiota play an important role in regulation and propagation of encephalitogenic immune response. Therefore, modulation of AO gut microbiota by antibiotics was performed in this study. The treatment altered composition of gut microbiota in AO rats and led to a reduction in the proportion of regulatory T cells in Peyer's patches, mesenteric lymph nodes, and in lymph nodes draining the site of immunization. Upregulation of interferon-γ and interleukin (IL)-17 production was observed in the draining lymph nodes. The treatment led to clinically manifested EAE in AO rats with more numerous infiltrates and higher production of IL-17 observed in the CNS. Importantly, transfer of AO gut microbiota into EAE-prone Dark Agouti rats ameliorated the disease. These results clearly imply that gut microbiota is an important factor in AO rat resistance to EAE and that gut microbiota transfer is an efficacious way to treat CNS autoimmunity. These findings also support the idea that gut microbiota modulation has a potential as a future treatment of multiple sclerosis.

Potential molecular mimicry between the human endogenous retrovirus W family envelope proteins and myelin proteins in multiple sclerosis

Multiple sclerosis is an autoimmune disease caused by the destruction of the myelin sheath in the central nervous system. The major target molecules for the immune response are the myelin basic protein, myelin oligodendrocyte glycoprotein and proteolipid protein but the aetiology of the disease is as yet poorly understood. The HLA Class II allele DRB1*1501 in particular as well as DRB5*0101 and the expression of human endogenous retroviral envelope proteins have been linked to multiple sclerosis but the molecular mechanisms relating these remain to be elucidated. We hypothesised that cross-reactive peptide epitopes in retroviral envelope proteins and myelin proteins that can be presented by the two Class II DR molecules may play a role in initiating multiple sclerosis. Sequence homologies between retroviral envelope and myelin proteins and in silico predictions of peptides derived from them that are able to bind to the two Class II alleles were examined to test the hypothesis. The results support the hypothesis that molecular mimicry in peptide epitopes from envelope proteins of the HERV-W family of endogenous retroviruses and myelin proteins is possible and could potentially trigger multiple sclerosis. Mimicry between syncytin-1, a HERV-W envelope protein that is expressed during placentation, and myelin proteins may also explain the higher prevalence of multiple sclerosis in women. Experiments to test the ability of the identified peptide epitopes to activate T_H cells are required to confirm the present findings.

Optical coherence tomography and T cell gene expression analysis in patients with benign multiple sclerosis

Benign multiple sclerosis is a retrospective diagnosis based primarily on a lack of motor symptom progression. Recent findings that suggest patients with benign multiple sclerosis experience non-motor symptoms highlight the need for a more prospective means to diagnose benign multiple sclerosis early in order to help direct patient care. In this study, we present optical coherence tomography and T cell neurotrophin gene analysis findings in a small number of patients with benign multiple sclerosis. Our results demonstrated that retinal nerve fiber layer was mildly thinned, and T cells had a distinct gene expression profile that included upregulation of interleukin 10 and leukemia inhibitory factor, downregulation of interleukin 6 and neurotensin high affinity receptor 1 (a novel neurotrophin receptor). These findings add evidence for further investigation into optical coherence tomography and mRNA profiling in larger cohorts as a potential means to diagnose benign multiple sclerosis in a more prospective manner.