Increased frequencies of myelin oligodendrocyte glycoprotein/MHC class II-binding CD4 cells in patients with multiple sclerosis

Animal model of multiple sclerosis: Experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is a very complex and heterogeneous disease, with an unknown etiology and which, currently, remains incurable. For this reason, animal models are crucial to investigate this disease, which has increased in prevalence in recent years, affecting 2.8 million people worldwide, and is the leading cause of non-traumatic disability in young adults between the ages of 20-30years. Of all the models developed to replicate MS, experimental autoimmune encephalomyelitis (EAE) best reflects the autoimmune pathogenesis of MS. There are different methods to induce it, which will give rise to different types of EAE, which will vary in clinical presentation and severity. Of the EAE models, the most widespread and used is the one induced in rodents due to its advantages over other species. Likewise, EAE has become a widely used model in the development of therapies for the treatment of MS. Likewise, it is very useful to define the cellular and molecular mechanisms involved in the pathogenesis of MS and to establish therapeutic targets for this disease. For all these reasons, the EAE model plays a key role in improving the understanding of MS.

Emerging T cell immunoregulatory mechanisms in multiple sclerosis and Alzheimer's disease

Multiple sclerosis (MS) and Alzheimer's disease (AD) are neuroinflammatory and neurodegenerative diseases with considerable socioeconomic impacts but without definitive treatments. AD and MS have multifactorial pathogenesis resulting in complex cognitive and neurologic symptoms and growing evidence also indicates key functions of specific immune cells. Whereas relevant processes dependent on T cells have been elucidated in both AD and MS, mechanisms that can control such immune responses still remain elusive. Here, a brief overview of select recent findings clarifying immunomodulatory mechanisms specifically induced by tolerogenic dendritic cells to limit the activation and functions of neurodegenerative T cells is presented. These insights could become a foundation for new cutting-edge research as well as therapeutic strategies.

Simultaneous and Multimodal Antigen-Binding Profiling and Isolation of Rare Cells via Quantitative Ferrohydrodynamic Cell Separation

Simultaneous cell profiling and isolation based on cellular antigen-binding capacity plays an important role in understanding and treating diseases. However, fluorescence-activated cell sorting (FACS) and magnetic-activated cell sorting (MACS) are not able to meet this need, due to their requirement for a large quantity of target cells and the limitation stemming from bimodal separation. Here we report a microfluidic method, termed quantitative ferrohydrodynamic cell separation (qFCS), that achieved multimodal rare cell sorting and simultaneous antigen profiling at a ∼30,000 cell min^-1 throughput with a 96.49% recovery rate and a 98.72% purity of recovered cells. qFCS profiles and sorts cells via cellular magnetic content of the magnetically labeled cells, which correlates to cellular antigen-binding capacity. By integrating cellular magnetophoresis and diamagnetophoresis in biocompatible ferrofluids, we demonstrate that the resulting qFCS device can accurately profile and isolate rare cells even when present at ∼1:50,000 target to background cells frequency. We show that the qFCS device could accurately profile and isolate T lymphocytes based on a low-expression CD154 antigen and allow on-device analysis of cells after processing. This method could address the need for simultaneous and multimodal rare cell isolation and profiling in disease diagnostics, prognostics, and treatment.

Contribution of Intravital Neuroimaging to Study Animal Models of Multiple Sclerosis

Multiple sclerosis (MS) is a complex and long-lasting neurodegenerative disease of the central nervous system (CNS), characterized by the loss of myelin within the white matter and cortical fibers, axonopathy, and inflammatory responses leading to consequent sensory-motor and cognitive deficits of patients. While complete resolution of the disease is not yet a reality, partial tissue repair has been observed in patients which offers hope for therapeutic strategies. To address the molecular and cellular events of the pathomechanisms, a variety of animal models have been developed to investigate distinct aspects of MS disease. Recent advances of multiscale intravital imaging facilitated the direct in vivo analysis of MS in the animal models with perspective of clinical transfer to patients. This review gives an overview of MS animal models, focusing on the current imaging modalities at the microscopic and macroscopic levels and emphasizing the importance of multimodal approaches to improve our understanding of the disease and minimize the use of animals.

Evaluation of methods of modeling and formation of experimental allergic encephalomyelitis

Introduction: Experimental autoimmune (allergic) encephalomyelitis (EAE) induced by intradermal injection of homogenate of the brain, spinal cord and peripheral nerve with Freund’s stimulator, refers to a true autoimmune disease of the nervous system.

Materials and methods: Experimental studies were conducted on white nonlinear rats. To induce experimental allergic encephalomyelitis (EAE), homologous brain homogenates was used, which leads among other drugs (homologous, heterogeneous brain and spinal cord homogenates) by encephalitogenity. The connective tissue of the animal’s tail base was injected with a mixture of encephalitogenic suspension of 0.1 ml per 100 g of the body weight.

Results and discussion: According to the results, in the rats, there was weight loss, and the abnormal neurological symptoms were found on an average of 10–12th days. Our experimental studies on the formation of EAE were confirmed morphologically by electron microscopy.

Conclusion: Thus, the use of this technique allowed us to obtain a simulated pathologic condition of multiple sclerosis in the form of experimental allergic encephalomyelitis and can be used in future studies to identify appropriate laws, the extent and nature of changes in the immune and nervous systems of the body when inducing experimental pathological conditions.

Neuroprotective Potential of Dendritic Cells and Sirtuins in Multiple Sclerosis

Myeloid cells, including parenchymal microglia, perivascular and meningeal macrophages, and dendritic cells (DCs), are present in the central nervous system (CNS) and establish an intricate relationship with other cells, playing a crucial role both in health and in neurological diseases. In this context, DCs are critical to orchestrating the immune response linking the innate and adaptive immune systems. Under steady-state conditions, DCs patrol the CNS, sampling their local environment and acting as sentinels. During neuroinflammation, the resulting activation of DCs is a critical step that drives the inflammatory response or the resolution of inflammation with the participation of different cell types of the immune system (macrophages, mast cells, T and B lymphocytes), resident cells of the CNS and soluble factors. Although the importance of DCs is clearly recognized, their exact function in CNS disease is still debated. In this review, we will discuss modern concepts of DC biology in steady-state and during autoimmune neuroinflammation. Here, we will also address some key aspects involving DCs in CNS patrolling, highlighting the neuroprotective nature of DCs and emphasizing their therapeutic potential for the treatment of neurological conditions. Recently, inhibition of the NAD⁺-dependent deac(et)ylase sirtuin 6 was demonstrated to delay the onset of experimental autoimmune encephalomyelitis, by dampening DC trafficking towards inflamed LNs. Thus, a special focus will be dedicated to sirtuins’ role in DCs functions.

Mechanistic and Biomarker Studies to Demonstrate Immune Tolerance in Multiple Sclerosis

The induction of specific immunological tolerance represents an important therapeutic goal for multiple sclerosis and other autoimmune diseases. Sound knowledge of the target antigens, the underlying pathomechanisms of the disease and the presumed mechanisms of action of the respective tolerance-inducing approach are essential for successful translation. Furthermore, suitable tools and assays to evaluate the induction of immune tolerance are key aspects for the development of such treatments. However, investigation of the mechanisms of action underlying tolerance induction poses several challenges. The optimization of sensitive, robust methods which allow the assessment of low frequency autoreactive T cells and the long-term reduction or change of their responses, the detection of regulatory cell populations and their immune mediators, as well as the validation of specific biomarkers indicating reduction of inflammation and damage, are needed to develop tolerance-inducing approaches successfully to patients. This short review focuses on how to demonstrate mechanistic proof-of-concept in antigen-specific tolerance-inducing therapies in MS.

Advanced Genomics-Based Approaches for Defining Allograft Rejection With Single Cell Resolution

Solid organ transplant recipients require long-term immunosuppression for prevention of rejection. Calcineurin inhibitor (CNI)-based immunosuppressive regimens have remained the primary means for immunosuppression for four decades now, yet little is known about their effects on graft resident and infiltrating immune cell populations. Similarly, the understanding of rejection biology under specific types of immunosuppression remains to be defined. Furthermore, development of innovative, rationally designed targeted therapeutics for mitigating or preventing rejection requires a fundamental understanding of the immunobiology that underlies the rejection process. The established use of microarray technologies in transplantation has provided great insight into gene transcripts associated with allograft rejection but does not characterize rejection on a single cell level. Therefore, the development of novel genomics tools, such as single cell sequencing techniques, combined with powerful bioinformatics approaches, has enabled characterization of immune processes at the single cell level. This can provide profound insights into the rejection process, including identification of resident and infiltrating cell transcriptomes, cell-cell interactions, and T cell receptor α/β repertoires. In this review, we discuss genomic analysis techniques, including microarray, bulk RNAseq (bulkSeq), single-cell RNAseq (scRNAseq), and spatial transcriptomic (ST) techniques, including considerations of their benefits and limitations. Further, other techniques, such as chromatin analysis via assay for transposase-accessible chromatin sequencing (ATACseq), bioinformatic regulatory network analyses, and protein-based approaches are also examined. Application of these tools will play a crucial role in redefining transplant rejection with single cell resolution and likely aid in the development of future immunomodulatory therapies in solid organ transplantation.

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

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

Identification of Human Antigen-Specific CD4+ Cells with Peptide-MHC Multimer Technologies

Peptide-major histocompatibility complex class II (pMHCII) multimers have emerged as a convenient and powerful tool for characterization of CD4 T cell immune responses in a large variety of human diseases. Peptide-MHCII multimers can rapidly identify peptide antigens recognized by CD4 T cells via high-throughput peptide screening procedures. The specificity and phenotype of antigen-specific CD4 T cells can be effectively visualized by pMHCII multimers from unmanipulated immune cell populations. Functional attributes of antigen-specific CD4 T cells can also be defined with the multimer technology in combination with immune functional assays such as intracellular cytokine staining (ICS).

Detection of autoreactive CD4+ T cells by MHC class II multimers in HLA-linked human autoimmune diseases

Recognition of self-peptides in association with distinct HLA class II alleles by autoreactive CD4+ T cells is central for loss of immunological tolerance leading to autoimmune disease. However, identifying immunodominant self-peptides and characterizing autoreactive T cells is challenging. In this issue of the JCI, Falta et al. identify a disease-associated complementarity-determining region 3β motif specific for beryllium-modified C-C motif ligand 4 (CCL4) and CCL3 self-peptides in patients with chronic beryllium disease (CBD), a granulomatous lung disorder with a known HLA class II allelic association. Detection of these antigen-specific CD4+ T cells by beryllium-pulsed HLA-DP2 tetramers presenting CCL4/CCL3 confirms these autoantigens in humans and mice and enables monitoring in the progress of disease. Detection of autoreactive CD4+ T cells by peptide-MHC class II multimers allows for the detailed characterization of disease-promoting T cells. This knowledge has profound implications for the monitoring and development of targeted therapies in human autoimmune disorders.

Antigen-Specific Immune Tolerance in Multiple Sclerosis-Promising Approaches and How to Bring Them to Patients

Antigen-specific tolerance induction aims at treating multiple sclerosis (MS) at the root of its pathogenesis and has the prospect of personalization. Several promising tolerization approaches using different technologies and modes of action have already advanced to clinical testing. The prerequisites for successful tolerance induction include the knowledge of target antigens, core pathomechanisms, and how to pursue a clinical development path that is distinct from conventional drug development. Key aspects including patient selection, outcome measures, demonstrating the mechanisms of action as well as the positioning in the rapidly growing spectrum of MS treatments have to be considered to bring this therapy to patients.

Administration of CD4+CD25highCD127-FoxP3+ Regulatory T Cells for Relapsing-Remitting Multiple Sclerosis: A Phase 1 Study

BACKGROUND

Multiple sclerosis (MS) is an immune-mediated disease in which autoimmune T conventional (T_conv) cells break the blood-brain barrier and destroy neurons of the central nervous system. It is hypothesized that CD4⁺CD25^highCD127^-FoxP3⁺ T regulatory (T_reg) cells may inhibit this destruction through suppressive activity exerted on T_conv cells.

METHODS

We present the results of a phase 1b/2a, open-label, two-arm clinical trial in 14 patients treated with autologous T_reg cells for relapsing-remitting MS. The patients received either expanded ex vivo T_reg cells intravenously (intravenous [IV] group, n = 11; dose 40 × 10⁶ T_reg cells/kg of body weight) or freshly isolated T_reg cells intrathecally (intrathecal [IT] group, n = 3; dose 1.0 × 10⁶ T_reg cells). Importantly, patients were not treated with any other disease-modifying drugs for at least 6 months before the recruitment and during the follow-up.

RESULTS

No severe adverse events were observed. Self-assessed quality of life (EuroQol-5 Dimensions [EQ-5D] form) did not change and did not differ significantly between the groups. A total of 12 relapses were noted in five intravenously treated patients, who had from one to three attacks per year. Three out of ten participants who completed the trial in the IV group deteriorated more than 1 point on the Expanded Disability Status Scale (EDSS) during the follow-up. At the same time, no patients in the IT group experienced a relapse or such a deterioration in the EDSS. No significant differences were found in the Multiple Sclerosis Functional Composite (MSFC) scale in both the IV and IT groups. Magnetic resonance imaging (MRI) scans revealed a significantly lower change in the T2 lesion volume in the IT group compared to the IV group. The increase in the number of new T2 lesions during the follow-up was significant for the IV group only. There were no significant changes in the level of T_reg cells or T_conv cells in the peripheral blood throughout the follow-up or between the groups. Interestingly, T_reg cells in all patients consisted of two different phenotypes: peripheral T_reg cells Helios(-) (≈ 20%) and thymic T_reg cells Helios(+) (≈ 80%). The analysis of the cytokine pattern revealed higher levels of transforming growth factor-α and proinflammatory factors MCP3, CXCL8, and IL-1RA in the IT group compared with the IV group.

CONCLUSIONS

No serious adverse events were reported in the 14 patients with MS treated with T_reg cells in this study. The results suggest that IT administration is more promising than IV administration. Because of the low number of patients recruited, the statistical results may be underpowered and further studies are necessary to reach conclusions on efficacy and safety.

TRIAL REGISTRATION

EudraCT: 2014-004320-22; registered 18 November 2014.

HLA Class II Genotype Does Not Affect the Myelin Responsiveness of Multiple Sclerosis Patients

Background: When aiming to restore myelin tolerance using antigen-specific treatment approaches in MS, the wide variety of myelin-derived antigens towards which immune responses are targeted in multiple sclerosis (MS) patients needs to be taken into account. Uncertainty remains as to whether the myelin reactivity pattern of a specific MS patient can be predicted based upon the human leukocyte antigen (HLA) class II haplotype of the patient. Methods: In this study, we analyzed the reactivity towards myelin oligodendrocyte glycoprotein (MOG), myelin basic protein (MBP) and proteolipid protein (PLP) peptides using direct interferon (IFN)-γ enzyme-linked immune absorbent spot (ELISPOT). Next, the HLA class II haplotype profile was determined by next-generation sequencing. In doing so, we aimed to evaluate the possible association between the precursor frequency of myelin-reactive T cells and the HLA haplotype. Results: Reactivity towards any of the analyzed peptides could be demonstrated in 65.0% (13/20) of MS patients and in 60.0% (6/10) of healthy controls. At least one of the MS risk alleles HLA-DRB1*15:01, HLA-DQA1*01:02 and HLA-DQB1*06:02 was found in 70.0% (14/20) of patients and in 20.0% (2/10) of healthy controls. No difference in the presence of a myelin-specific response, nor in the frequency of myelin peptide-reactive precursor cells could be detected among carriers and non-carriers of these risk alleles. Conclusion: No association between HLA haplotype and myelin reactivity profile was present in our study population. This complicates the development of antigen-specific treatment approaches and implies the need for multi-epitope targeting in an HLA-unrestricted manner to fully address the wide variation in myelin responses and HLA profiles in a heterogeneous group of MS patients.

Immune System Sex Differences May Bridge the Gap Between Sex and Gender in Fibromyalgia

The fibromyalgia syndrome (FMS) is characterized by chronic widespread pain, sleep disturbances, fatigue, and cognitive alterations. A limited efficacy of targeted treatment and a high FMS prevalence (2–5% of the adult population) sums up to high morbidity. Although, altered nociception has been explained with the central sensitization hypothesis, which may occur after neuropathy, its molecular mechanism is not understood. The marked female predominance among FMS patients is often attributed to a psychosocial predisposition of the female gender, but here we will focus on sex differences in neurobiological processes, specifically those of the immune system, as various immunological biomarkers are altered in FMS. The activation of innate immune sensors is compatible with a neuropathy or virus-induced autoimmune diseases. Considering sex differences in the immune system and the clustering of FMS with autoimmune diseases, we hypothesize that the female predominance in FMS is due to a neuropathy-induced autoimmune pathophysiology. We invite the scientific community to verify the autoimmune hypothesis for FMS.

CXCR3+ T cells in multiple sclerosis correlate with reduced diversity of the gut microbiome

Multiple sclerosis (MS) is a genetically mediated autoimmune disease characterized by inflammation in the central nervous system (CNS). Disease onset is thought to occur when autoreactive T cells orchestrate a cascade of events in the CNS resulting in white and grey matter inflammation and axonal degeneration. It is unclear what triggers the activation of CNS-reactive T cells and their polarization into inflammatory subsets. Mounting evidence from animal and human studies supports the hypothesis that the gut microbiome affects MS pathogenesis. We investigated the association between the gut microbiome and inflammatory T cell subsets in relapsing-remitting MS patients and healthy controls. Gut microbiome composition was characterized by sequencing the V4 region of the 16S rRNA gene from fecal DNA, and inflammatory T cell subsets were characterized by flow cytometry. We identified an altered gut microbiome in MS patients, including decreased abundance of Coprococcus, Clostridium, and an unidentified Ruminococcaceae genus. Among circulating immune cells, patients had increased expression of CXCR3 in both CD4 and CD8 T cells, and both CD4+CXCR3+ and CD8+CXCR3+ populations expressing the gut-homing α4β7 integrin receptor were increased. Finally, we show that alpha diversity inversely correlated with a CXCR3+ Th1 phenotype in MS. These findings indicate the presence of an aberrant gut-immune axis in patients with MS.

HLA DR2b-binding peptides from human endogenous retrovirus envelope, Epstein-Barr virus and brain proteins in the context of molecular mimicry in multiple sclerosis

The aetiology of multiple sclerosis (MS) is as yet poorly understood. Multiple mechanisms in different disease stages are responsible for immunopathology in MS. HLA Class II DR2b (DRB1*1501 β, DRA1*0101 α) is the strongest genetic risk factor for MS. Remnants of ancient retroviruses in the human genome, termed human endogenous retroviruses (HERV), and Epstein-Barr virus (EBV) infection are also associated with MS. In silico analyses of human endogenous retroviral envelope (HERV env) proteins and three myelin proteins that are principal targets of an autoimmune response in MS showed sequence similarities between potential T_H epitopes within pairs of viral and myelin peptides predicted to bind HLA DR2b. This led to the proposal that such molecular mimicry may potentially trigger MS. HLA DR2b binding characteristics of previously identified peptides from the three myelin proteins and HERV env proteins as well as additional in silico predicted peptides from other encephalitogenic brain proteins and EBV proteins were studied to further investigate molecular mimicry. Peptides containing potential T_H epitopes from the myelin oligodendrocyte glycoprotein and HERV env previously predicted to bind HLA DR2b as well as other pertinent potential HLA DR2b-restricted T_H epitopes were confirmed to bind HLA DR2b molecules. Molecular modelling of HLA DR2b in complex with high affinity peptides derived from MOG and HERV env proteins showed that their binding could occur in a similar manner to a HLA DR2b-binding peptide containing a known T_H epitope. A structurally related pair of peptides predicted to bind HLA DR2b from the EBV protein EBNA1 and β synuclein, a brain protein implicated in MS, were also shown to similarly bind HLA DR2b. The findings justify investigating CD4⁺ T cell responses to the identified peptides.

Commensal orthologs of the human autoantigen Ro60 as triggers of autoimmunity in lupus

The earliest autoantibodies in lupus are directed against the RNA binding autoantigen Ro60, but the triggers against this evolutionarily conserved antigen remain elusive. We identified Ro60 orthologs in a subset of human skin, oral, and gut commensal bacterial species and confirmed the presence of these orthologs in patients with lupus and healthy controls. Thus, we hypothesized that commensal Ro60 orthologs may trigger autoimmunity via cross-reactivity in genetically susceptible individuals. Sera from human anti-Ro60-positive lupus patients immunoprecipitated commensal Ro60 ribonucleoproteins. Human Ro60 autoantigen-specific CD4 memory T cell clones from lupus patients were activated by skin and mucosal Ro60-containing bacteria, supporting T cell cross-reactivity in humans. Further, germ-free mice spontaneously initiated anti-human Ro60 T and B cell responses and developed glomerular immune complex deposits after monocolonization with a Ro60 ortholog-containing gut commensal, linking anti-Ro60 commensal responses in vivo with the production of human Ro60 autoantibodies and signs of autoimmunity. Together, these data support that colonization with autoantigen ortholog-producing commensal species may initiate and sustain chronic autoimmunity in genetically predisposed individuals. The concept of commensal ortholog cross-reactivity may apply more broadly to autoimmune diseases and lead to novel treatment approaches aimed at defined commensal species.

Biomarkers in Multiple Sclerosis

Multiple sclerosis (MS) is a chronic neurodegenerative autoimmune disease with a complex clinical course characterized by inflammation, demyelination, and axonal degeneration. Diagnosis of MS most commonly includes finding lesions in at least two separate areas of the central nervous system (CNS), including the brain, spinal cord, and optic nerves. In recent years, there has been a remarkable increase in the number of available treatments for MS. An optimal treatment is usually based on a personalized approach determined by an individual patient's prognosis and treatment risks. Biomarkers that can predict disability progression, monitor ongoing disease activity, and assess treatment response are integral in making important decisions regarding MS treatment. This review describes MS biomarkers that are currently being used in clinical practice; it also reviews and consolidates published findings from clinically relevant potential MS biomarkers in recent years. The work also discusses the challenges of validating and application of biomarkers in MS clinical practice.

Anti-Myelin Oligodendrocyte Glycoprotein and Human Leukocyte Antigens as Markers in Pediatric and Adolescent Multiple Sclerosis: on Diagnosis, Clinical Phenotypes, and Therapeutic Responses

Early-onset (pediatric and adolescent) multiple sclerosis (MS) is a well-established demyelinating disease that accounts for approximately 3-5% of all MS cases. Thus, identifying potential biomarkers that can reflect the pathogenic mechanisms, disease course and prognosis, and therapeutic response in such patients is of paramount importance. Myelin oligodendrocyte glycoprotein (MOG) has been regarded as a putative autoantigen and autoantibody target in patients with demyelinating diseases for almost three decades. However, recent studies have suggested that antibodies against MOG represent a distinct clinical entity of dominantly humoral profile, with a range of clinical phenotypes closely related to the age of onset, specific patterns of disease course, and responses to treatment. Furthermore, the major histocompatibility complex (MHC)—which has been regarded as the “gold standard” for attributing genetic burden in adult MS since the early 1970s—has also emerged as the primary genetic locus in early-onset MS, particularly with regard to the human leukocyte antigen (HLA) alleles DRB1⁎1501 and DRB1⁎0401. Recent studies have investigated the potential interactions among HLA, MOG, and environmental factors, demonstrating that early-onset MS is characterized by genetic, immunogenetic, immunological, and familial trait correlations. In this paper, we review recent evidence regarding HLA-genotyping and MOG antibodies—the two most important candidate biomarkers for early-onset MS—as well as their potential application in the diagnosis and treatment of MS.

Experimental Autoimmune Encephalomyelitis (EAE) as Animal Models of Multiple Sclerosis (MS)

Multiple sclerosis (MS) is a multifocal demyelinating disease of the central nervous system (CNS) leading to the progressive destruction of the myelin sheath surrounding axons. It can present with variable clinical and pathological manifestations, which might reflect the involvement of distinct pathogenic processes. Although the mechanisms leading to the development of the disease are not fully understood, numerous evidences indicate that MS is an autoimmune disease, the initiation and progression of which are dependent on an autoimmune response against myelin antigens. In addition, genetic susceptibility and environmental triggers likely contribute to the initiation of the disease. At this time, there is no cure for MS, but several disease-modifying therapies (DMTs) are available to control and slow down disease progression. A good number of these DMTs were identified and tested using animal models of MS referred to as experimental autoimmune encephalomyelitis (EAE). In this review, we will recapitulate the characteristics of EAE models and discuss how they help shed light on MS pathogenesis and help test new treatments for MS patients.

Unsupervised capture and profiling of rare immune cells using multi-directional magnetic ratcheting

Immunotherapies (IT) require induction, expansion, and maintenance of specific changes to a patient's immune cell repertoire which yield a therapeutic benefit. Recently, mechanistic understanding of these changes at the cellular level has revealed that IT results in complex phenotypic transitions in target cells, and that therapeutic effectiveness may be predicted by monitoring these transitions during therapy. However, monitoring will require unique tools that enable capture, manipulation, and profiling of rare immune cell populations. In this study, we introduce a method of automated and unsupervised separation and processing of rare immune cells, using high-force and multidimensional magnetic ratcheting (MR). We demonstrate capture of target immune cells using samples with up to 1 : 10 000 target cell to background cell ratios from input volumes as small as 25 microliters (i.e. a low volume and low cell frequency sample sparing assay interface). Cell capture is shown to achieve up to 90% capture efficiency and purity, and captured cell analysis is shown using both on-chip culture/activity assays and off-chip ejection and nucleic acid analysis. These results demonstrate that multi-directional magnetic ratcheting offers a unique separation system for dealing with blood cell samples that contain either rare cells or significantly small volumes, and the "sample sparing" capability leads to an expanded spectrum of parameters that can be measured. These tools will be paramount to advancing techniques for immune monitoring under conditions in which both the sample volume and number of antigen-specific target cells are often exceedingly small, including during IT and treatment of allergy, asthma, autoimmunity, immunodeficiency, cell based therapy, transplantation, and infection.

Memory T cells specific to citrullinated α-enolase are enriched in the rheumatic joint

ACPA-positive rheumatoid arthritis (RA) is associated with distinct HLA-DR alleles and immune responses to many citrullinated self-antigens. Herein we investigated the T cell epitope confined within α-enolase_326-340 in the context of HLA-DRB1*04:01 and assessed the corresponding CD4⁺ T cells in both the circulation and in the rheumatic joint. Comparative crystallographic analyses were performed for the native and citrullinated α-enolase_326-340 peptides in complex with HLA-DRB1*04:01. HLA-tetramers assembled with either the native or citrullinated peptide were used for ex vivo and in vitro assessment of α-enolase-specific T cells in peripheral blood, synovial fluid and synovial tissue by flow cytometry. The native and modified peptides take a completely conserved structural conformation within the peptide-binding cleft of HLA-DRB1*04:01. The citrulline residue-327 was located N-terminally, protruding towards TCRs. The frequencies of T cells recognizing native eno_326-340 were similar in synovial fluid and peripheral blood, while in contrast, the frequency of T cells recognizing cit-eno_326-340 was significantly elevated in synovial fluid compared to peripheral blood (3.6-fold, p = 0.0150). Additionally, citrulline-specific T cells with a memory phenotype were also significantly increased (1.6-fold, p = 0.0052) in synovial fluid compared to peripheral blood. The native T cell epitope confined within α-enolase_326-340 does not appear to lead to complete negative selection of cognate CD4⁺ T cells. In RA patient samples, only T cells recognizing the citrullinated version of α-enolase_326-340 were found at elevated frequencies implicating that neo-antigen formation is critical for breach of tolerance.

Myelin injury in the central nervous system and Alzheimer's disease

Myelin is a membrane wrapped around the axon of the nerve cell, which is composed of the mature oligodendrocytes. The role of myelin is to insulate and prevent the nerve electrical impulses from the axon of the neurons to the axons of the other neurons, which is essential for the proper functioning of the nervous system. Minor changes in myelin thickness could lead to substantial changes in conduction speed and may thus alter neural circuit function. Demyelination is the myelin damage, which characterized by the loss of nerve sheath and the relative fatigue of the neuronal sheath and axon. Studies have shown that myelin injury may be closely related to neurodegenerative diseases and may be an early diagnostic criteria and therapeutic target. Thus this review summarizes the recent result of pathologic effect and signal pathways of myelin injury in neurodegenerative diseases, especially the Alzheimer's disease to provide new and effective therapeutic targets.

Multiple sclerosis: genetics, biomarkers, treatments

PURPOSE OF REVIEW

We discuss new paradigms for understanding the immunopathology of multiple sclerosis through the recent development of high throughput genetic analysis, emergence of numerous candidate biomarkers, and the broadening of the treatment arsenal.

RECENT FINDINGS

The recent use of genome wide association studies provide new tools for a better understanding of multiple sclerosis etiology. Genome-wide association studies have identified many genes implicated in immune regulation and the next step will be to elucidate how those genetic variations influence immune cell function to drive disease development and progression. Furthermore, patient care has seen the emergence of new biomarkers for monitoring disease progression and response to treatment. Finally, the introduction of numerous immunomodulatory treatments will likely improve clinical outcome of multiple sclerosis patients in the future.

SUMMARY

Breakthroughs in the field of multiple sclerosis have led to a better understanding of the physiopathology of the disease, follow up, and treatment of the patients that develop relapsing remitting multiple sclerosis. The next challenge for multiple sclerosis will be to press forward to model and decipher multiple sclerosis progression, which will help both to develop therapeutics and generate knowledge about mechanisms of neurodegeneration.

Peripherally Induced Regulatory T Cells: Recruited Protectors of the Central Nervous System against Autoimmune Neuroinflammation

Defects in regulatory T cells (Treg cells) aggravate multiple sclerosis (MS) after its onset and the absence of Treg cell functions can also exacerbate the course of disease in an animal model of MS. However, autoimmune neuroinflammation in many MS models can be acutely provoked in healthy animals leading to an activation of encephalitogenic T cells despite the induction of immune tolerance in the thymus including thymically produced (t)Treg cells. In contrast, neuroinflammation can be ameliorated or even completely prevented by the antigen-specific Treg cells formed extrathymically in the peripheral immune system (pTreg cells) during tolerogenic responses to relevant neuronal antigens. This review discusses the specific roles of Treg cells in blocking neuroinflammation, examines the impact of peripheral tolerance and dendritic cells on a relevant regulation of neuroinflammation, and explores some of the most recent advances in elucidation of specific mechanisms of the conversion and function of pTreg cells including the roles of CD5 and Hopx in these processes.

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.

PRMT5-Selective Inhibitors Suppress Inflammatory T Cell Responses and Experimental Autoimmune Encephalomyelitis

In the autoimmune disease multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis (EAE), expansion of pathogenic, myelin-specific Th1 cell populations drives active disease; selectively targeting this process may be the basis for a new therapeutic approach. Previous studies have hinted at a role for protein arginine methylation in immune responses, including T cell-mediated autoimmunity and EAE. However, a conclusive role for the protein arginine methyltransferase (PRMT) enzymes that catalyze these reactions has been lacking. PRMT5 is the main PRMT responsible for symmetric dimethylation of arginine residues of histones and other proteins. PRMT5 drives embryonic development and cancer, but its role in T cells, if any, has not been investigated. In this article, we show that PRMT5 is an important modulator of CD4⁺ T cell expansion. PRMT5 was transiently upregulated during maximal proliferation of mouse and human memory Th cells. PRMT5 expression was regulated upstream by the NF-κB pathway, and it promoted IL-2 production and proliferation. Blocking PRMT5 with novel, highly selective small molecule PRMT5 inhibitors severely blunted memory Th expansion, with preferential suppression of Th1 cells over Th2 cells. In vivo, PRMT5 blockade efficiently suppressed recall T cell responses and reduced inflammation in delayed-type hypersensitivity and clinical disease in EAE mouse models. These data implicate PRMT5 in the regulation of adaptive memory Th cell responses and suggest that PRMT5 inhibitors may be a novel therapeutic approach for T cell-mediated inflammatory disease.

Functional inflammatory profiles distinguish myelin-reactive T cells from patients with multiple sclerosis

Myelin-reactive T cells have been identified in patients with multiple sclerosis (MS) and healthy subjects with comparable frequencies, but the contribution of these autoreactive T cells to disease pathology remains unknown. A total of 13,324 T cell libraries generated from blood of 23 patients and 22 healthy controls were interrogated for reactivity to myelin antigens. Libraries derived from CCR6(+) myelin-reactive T cells from patients with MS exhibited significantly enhanced production of interferon-γ (IFN-γ), interleukin-17 (IL-17), and granulocyte-macrophage colony-stimulating factor (GM-CSF) compared to healthy controls. Single-cell clones isolated by major histocompatibility complex/peptide tetramers from CCR6(+) T cell libraries also secreted more proinflammatory cytokines, whereas clones isolated from controls secreted more IL-10. The transcriptomes of myelin-specific CCR6(+) T cells from patients with MS were distinct from those derived from healthy controls and, notably, were enriched in T helper cell 17 (TH17)-induced experimental autoimmune encephalitis gene signatures, and gene signatures derived from TH17 cells isolated other human autoimmune diseases. These data, although not causal, imply that functional differences between antigen-specific T cells from MS and healthy controls are fundamental to disease development and support the notion that IL-10 production from myelin-reactive T cells may act to limit disease progression or even pathogenesis.

Autoreactive T Cells from Patients with Myasthenia Gravis Are Characterized by Elevated IL-17, IFN-γ, and GM-CSF and Diminished IL-10 Production

Myasthenia gravis (MG) is a prototypical autoimmune disease that is among the few for which the target Ag and the pathogenic autoantibodies are clearly defined. The pathology of the disease is affected by autoantibodies directed toward the acetylcholine receptor (AChR). Mature, Ag-experienced B cells rely on the action of Th cells to produce these pathogenic Abs. The phenotype of the MG Ag-reactive T cell compartment is not well defined; thus, we sought to determine whether such cells exhibit both a proinflammatory and a pathogenic phenotype. A novel T cell library assay that affords multiparameter interrogation of rare Ag-reactive CD4(+) T cells was applied. Proliferation and cytokine production in response to both AChR and control Ags were measured from 3120 T cell libraries derived from 11 MG patients and paired healthy control subjects. The frequency of CCR6(+) memory T cells from MG patients proliferating in response to AChR-derived peptides was significantly higher than that of healthy control subjects. Production of both IFN-γ and IL-17, in response to AChR, was also restricted to the CCR6(+) memory T cell compartment in the MG cohort, indicating a proinflammatory phenotype. These T cells also included an elevated expression of GM-CSF and absence of IL-10 expression, indicating a proinflammatory and pathogenic phenotype. This component of the autoimmune response in MG is of particular importance when considering the durability of MG treatment strategies that eliminate B cells, because the autoreactive T cells could renew autoimmunity in the reconstituted B cell compartment with ensuing clinical manifestations.

Major Histocompatibility Complex Class II Dextramers: New Tools for the Detection of antigen-Specific, CD4 T Cells in Basic and Clinical Research

The advent of major histocompatibility complex (MHC) tetramer technology has been a major contribution to T cell immunology, because tetramer reagents permit detection of antigen-specific T cells at the single-cell level in heterogeneous populations by flow cytometry. However, unlike MHC class I tetramers, the utility of MHC class II tetramers has been less frequently reported. MHC class II tetramers can be used successfully to enumerate the frequencies of antigen-specific CD4 T cells in cells activated in vitro, but their use for ex vivo analyses continues to be a problem, due in part to their activation dependency for binding with T cells. To circumvent this problem, we recently reported the creation of a new generation of reagents called MHC class II dextramers, which were found to be superior to their counterparts. In this review, we discuss the utility of class II dextramers vis-a-vis tetramers, with respect to their specificity and sensitivity, including potential applications and limitations.

Susceptibility Genes for Multiple Sclerosis Identified in a Gene-Based Genome-Wide Association Study

Background and Purpose

Multiple sclerosis (MS) is a demyelinating and inflammatory disease of the central nervous system. The aim of this study was to identify more genes associated with MS.

Methods

Based on the publicly available data of the single-nucleotide polymorphism-based genome-wide association study (GWAS) from the database of Genotypes and Phenotypes, we conducted a powerful gene-based GWAS in an initial sample with 931 family trios, and a replication study sample with 978 cases and 883 controls. For interesting genes, gene expression in MS-related cells between MS cases and controls was examined by using publicly available datasets.

Results

A total of 58 genes was identified, including 20 "novel" genes significantly associated with MS (p<1.40×10^-4). In the replication study, 44 of the 58 identified genes had been genotyped and 35 replicated the association. In the gene-expression study, 21 of the 58 identified genes exhibited differential expressions in MS-related cells. Thus, 15 novel genes were supported by replicated association and/or differential expression. In particular, four of the novel genes, those encoding myelin oligodendrocyte glycoprotein (MOG), coiled-coil alpha-helical rod protein 1 (CCHCR1), human leukocyte antigen complex group 22 (HCG22), and major histocompatibility complex, class II, DM alpha (HLA-DMA), were supported by the evidence of both.

Conclusions

The results of this study emphasize the high power of gene-based GWAS in detecting the susceptibility genes of MS. The novel genes identified herein may provide new insights into the molecular genetic mechanisms underlying MS.

Role of T Follicular Helper cells in Multiple Sclerosis

Multiple Sclerosis (MS) is a chronic, inflammatory and neurodegenerative disease which results from the destruction of myelin and associated collateral tissue damage within the central nervous system (CNS). MS is a highly diverse disease with different clinical profiles. During the past decade, several new treatment options have been introduced, but no treatment completely stops the disease progression. Therefore deeper understanding of the disease mechanism is necessary to develop novel therapeutic strategies. While yet to be proven, there is evidence suggesting the involvement of T follicular helper (Tfh) cells, a CD4 T cell subset specialized for the provision of help to B cells, in the pathogenesis of MS. In this review, I will discuss the potential pathogenic roles of Tfh cells in the course of MS.

Antigen Presentation, Autoantigens, and Immune Regulation in Multiple Sclerosis and Other Autoimmune Diseases

Antigen presentation is in the center of the immune system, both in host defense against pathogens, but also when the system is unbalanced and autoimmune diseases like multiple sclerosis (MS) develop. It is not just by chance that a major histocompatibility complex gene is the major genetic susceptibility locus in MS; a feature that MS shares with other autoimmune diseases. The exact etiology of the disease, however, has not been fully understood yet. T cells are regarded as the major players in the disease, but most probably a complex interplay of altered central and peripheral tolerance mechanisms, T-cell and B-cell functions, characteristics of putative autoantigens, and a possible interference of environmental factors like microorganisms are at work. In this review, new data on all these different aspects of antigen presentation and their role in MS will be discussed, probable autoantigens will be summarized, and comparisons to other autoimmune diseases will be drawn.

Decreased Frequency of Circulating Myelin Oligodendrocyte Glycoprotein B Lymphocytes in Patients with Relapsing-Remitting Multiple Sclerosis

Although there is no evidence for a role of anti-MOG antibodies in adult MS, no information on B lymphocytes with MOG-committed BCR is available. We report here on the frequency of anti-MOG B cells forming rosettes with polystyrene beads (BBR) covalently bound to the extracellular domain of rhMOG in 38 relapsing-remitting patients (RRMS) and 50 healthy individuals (HI). We show a substantial proportion of circulating anti-MOG-BBR in both RRMS and HI. Strikingly, MOG-specific B cells frequencies were lower in MS than in HI. Anti-MOG antibodies measured by a cell-based assay were not different between MS patients and controls, suggesting a specific alteration of anti-MOG B cells in MS. Although anti-MOG-BBR were higher in CNS fluid than in blood, no difference was observed between MS and controls. Lower frequency of MOG-BBR in MS was not explained by an increased apoptosis, but a trend for lower proliferative capacity was noted. Despite an efficient B cell transmigration across brain derived endothelial cells, total and anti-MOG B cells transmigration was similar between MS and HI. The striking alteration in MOG-specific B cells, independent of anti-MOG antibody titers, challenges our view on the role of MOG-specific B cells in MS.

Role of viruses and bacteria-virus interactions in autoimmunity

A potential role for viral and bacterial-viral interactions in the pathogenesis of autoimmune disease has been long recognized. Recently, intensive investigation has begun to decipher interactions between specific microbes with the host that contribute toward autoimmunity. This work has primarily focused on known viral and bacterial pathogens. A major challenge is to determine the role of bacteria that are typically considered as commensals as well as chronic viruses. Furthermore, equally challenging is to prove causality given the potential complexity of microbe-microbe interactions. Important initial contributions to this field have shown that specific interactions of microbes with hosts that contain a background of genetic susceptibility can play a role in autoimmune pathogenesis. In this review, we describe principles of immune tolerance with a focus on its breakdown during pathogenic as well as commensal relationships between the host and the microbial world.

A humanized mouse model of autoimmune insulitis

Many mechanisms of and treatments for type 1 diabetes studied in the NOD mouse model have not been replicated in human disease models. Thus, the field of diabetes research remains hindered by the lack of an in vivo system in which to study the development and onset of autoimmune diabetes. To this end, we characterized a system using human CD4(+) T cells pulsed with autoantigen-derived peptides. Six weeks after injection of as few as 0.5 × 10(6) antigen-pulsed cells into the NOD-Scid Il2rg(-/-) mouse expressing the human HLA-DR4 transgene, infiltration of mouse islets by human T cells was seen. Although islet infiltration occurred with both healthy and diabetic donor antigen-pulsed CD4(+) T cells, diabetic donor injections yielded significantly greater levels of insulitis. Additionally, significantly reduced insulin staining was observed in mice injected with CD4(+) T-cell lines from diabetic donors. Increased levels of demethylated β-cell-derived DNA in the bloodstream accompanied this loss of insulin staining. Together, these data show that injection of small numbers of autoantigen-reactive CD4(+) T cells can cause a targeted, destructive infiltration of pancreatic β-cells. This model may be valuable for understanding mechanisms of induction of human diabetes.

Regulatory T cells in autoimmune neuroinflammation

Regulatory T cells are the central element for the maintenance of peripheral tolerance. Several subtypes of regulatory T (Treg) cells have been described, and most of them belong to the CD4(+) T-helper (Th) cell lineage. These specific subtypes can be discriminated according to phenotype and function. Forkhead box protein 3 (FoxP3)-expressing natural Treg cells (Tregs) and IL-10-producing, T-regulatory type 1 cells (Tr1) are the best-studied types of CD4(+) regulatory T cells in humans and experimental animal models. It was shown that they play a crucial role during autoimmune neuroinflammation. Both cells types seem to be particularly important for multiple sclerosis (MS). Here, we discuss the role of CD4(+) regulatory T cells in autoimmune neuroinflammation with an emphasis on Tregs and Tr1 cells in MS.

Autoimmune T-cell reactivity to myelin proteolipids and glycolipids in multiple sclerosis

Central nervous system (CNS) myelin, the likely major target of autoimmune attack in multiple sclerosis (MS), contains a number of unique components that are potential targets of the attack. Two classes of molecules that are greatly enriched in CNS myelin compared to other parts of the body are certain types of proteolipids and glycolipids. Due to the hydrophobic nature of both of these classes of molecules, they present challenges for use in immunological assays and have therefore been somewhat neglected in studies of T-cell reactivity in MS compared to more soluble molecules such as the myelin basic proteins and the extracellular domain of myelin oligodendrocyte glycoprotein. This review firstly looks at the makeup of CNS myelin, with an emphasis on proteolipids and glycolipids. Next, a retrospective of what is known of T-cell reactivity directed against proteolipids and glycolipids in patients with MS is presented, and the implications of the findings are discussed. Finally, this review considers the question of what would be required to prove a definite role for autoreactivity against proteolipids and glycolipids in the pathogenesis of MS.

The plasticity of human Treg and Th17 cells and its role in autoimmunity

CD4(+) T helper cells are a central element of the adaptive immune system. They protect the organism against a wide range of pathogens and are able to initiate and control many immune reactions in combination with other cells of the adaptive and the innate immune system. Starting from a naive cell, CD4(+) T cells can differentiate into various effector cell populations with specialized function. This subset specific differentiation depends on numerous signals and the strength of stimulation. However, recent data have shown that differentiated CD4(+) T cell subpopulations display a high grade of plasticity and that their initial differentiation is not an endpoint of T cell development. In particular, FoxP3(+) regulatory T cells (Treg) and Th17 effector T cells demonstrate a high grade of plasticity, which allow a functional adaptation to various physiological situations during an immune response. However, the plasticity of Treg and Th17 cells might also be a critical factor for autoimmune disease. Here we discuss the recent developments in CD4(+) T cell plasticity with a focus on Treg and Th17 cells and its role in human autoimmune disease, in particular multiple sclerosis (MS).

Familial CD3+ T large granular lymphocyte leukemia: evidence that genetic predisposition and antigen selection promote clonal cytotoxic T-cell responses

CD3+ T-large granular lymphocyte (T-LGL) proliferations often present with cytopenias and splenomegaly and are linked to autoimmunity, especially rheumatoid arthritis and Felty's syndrome. We report here the intra-family occurrence of T-LGL leukemia in a father and son, both presenting with cytopenias and splenomegaly. Both patients carried the HLA-DRB1*04 allele, strongly associated with rheumatoid arthritis and Felty's syndrome, exhibited distinctive histopathological features suggestive of immune-mediated suppression of hematopoiesis and expressed a remarkably skewed T-cell receptor beta chain gene repertoire with overtime evolution (clonal drift). Immunoinformatics analysis and comparisons with clonotype sequences from various entities revealed (quasi)identities between (i) father and son, and (ii) father or son and patients with autoimmune disorders, T-LGL leukemia or chronic idiopathic neutropenia. Altogether, our results further corroborate antigen selection in the ontogeny of T-LGL leukemia and point to the interplay between genetics and the (micro)environment in shaping the outcome of cytotoxic T cell responses.

Monitoring the Dynamics of T Cell Clonal Diversity Using Recombinant Peptide:MHC Technology

The capacity to probe antigen specific T cells within the polyclonal repertoire has been revolutionized by the advent of recombinant peptide:MHC (pMHC) technology. Monomers and multimers of pMHC molecules can enrich for and identify antigen specific T cells to elucidate the contributions of T cell frequency, localization, and T cell receptor (TCR) affinity during immune responses. Two-dimensional (2D) measurements of TCR–pMHC interactions are at the forefront of this field because the biological topography is replicated such that TCR and pMHC are membrane anchored on opposing cells, allowing for biologically pertinent measures of TCR antigen specificity and diversity. 2D measurements of TCR-pMHC kinetics have also demonstrated increased fidelity compared to three-dimensional surface plasmon resonance data and are capable of detecting T cell affinities that are below the detection level of most pMHC multimers. Importantly, 2D techniques provide a platform to evaluate T cell affinity and antigen specificity against multiple protein epitopes within the polyclonal repertoire directly ex vivo from sites of ongoing immune responses. This review will discuss how antigen specific pMHC molecules, with a focus on 2D technologies, can be used as effective tools to evaluate the range of TCR affinities that comprise an immune response and more importantly how the breadth of affinities determine functional outcome against a given exposure to antigen.

Superantigens induce IL-17 production from polarized Th1 clones

Differentiation of naïve CD4(+) T cells has been considered to be an irreversible event and, in particular, the plasticity is believed to be completely lost in Th1 subset in vitro after multiple stimulations. However, here we demonstrate that highly polarized myelin oligodendrocyte glycoprotein (MOG)- and herpes simples virus-specific Th1 clones were still capable of producing IL-17 upon superantigen stimulation. Anti-MHC class-II and anti-TCR αβ chains partially blocked superantigen-induced IL-17 production. These findings suggest that fully differentiated Th1 cells still have capability to produce cytokines of other Th subsets and production of IL-17 by MOG-specific Th1 cells may have implication in initiation and/or exacerbation of neurological autoimmune diseases.

Revisiting the old link between infection and autoimmune disease with commensals and T helper 17 cells

Genetic composition and major histocompatibility complex polymorphisms unequivocally predispose to autoimmune disease, but environmental factors also play a critical role in precipitating disease in susceptible individuals. Notorious among these has been microbial infection. Older studies describing associations between microbial infection and autoimmune disease are now followed by new studies demonstrating correlations between susceptibility to autoimmune disease and commensal colonization of the intestinal tract. T helper 17 (T(H)17) cells have gained a prominent role in autoimmune disease, and notably, their development within the intestine has been linked to colonization with specific commensal bacteria. Here, we consider current views on how microbes, T(H)17 cells, and autoimmunity are connected. We speculate on how the intricate relationships among commensal, pathogen, and the host might ultimately determine susceptibility to autoimmune disease.

Origins and significance of astrogliosis in the multiple sclerosis model, MOG peptide EAE

Astroglia, the most abundant cells in the human CNS, and even more prominent in multiple sclerosis patients, participate in CNS innate and adaptive immunity, and have been hypothesized to play an important role in multiple sclerosis progression. Experimental autoimmune encephalomyelitis elicited in mice by immunization with myelin oligodendrocyte glycoprotein peptide 35-55 provides a means by which to explore the genesis and disease significance of astrogliosis during a chronic immune-mediated CNS inflammatory/demyelinative disorder that, in its' pathological features, strongly resembles multiple sclerosis.

Dendritic cells and multiple sclerosis: disease, tolerance and therapy

Multiple sclerosis (MS) is a devastating neurological disease that predominantly affects young adults resulting in severe personal and economic impact. The majority of therapies for this disease were developed in, or are beneficial in experimental autoimmune encephalomyelitis (EAE), the animal model of MS. While known to target adaptive anti-CNS immune responses, they also target, the innate immune arm. This mini-review focuses on the role of dendritic cells (DCs), the professional antigen presenting cells of the innate immune system. The evidence for a role for DCs in the appropriate regulation of anti-CNS autoimmune responses and their role in MS disease susceptibility and possible therapeutic utility are discussed. Additionally, the current controversy regarding the evidence for the presence of functional DCs in the normal CNS is reviewed. Furthermore, the role of CNS DCs and potential routes of their intercourse between the CNS and cervical lymph nodes are considered. Finally, the future role that this nexus between the CNS and the cervical lymph nodes might play in site directed molecular and cellular therapy for MS is outlined.

Identifying autoantigens in demyelinating diseases: valuable clues to diagnosis and treatment?

PURPOSE OF REVIEW

Identification of autoantigens in demyelinating diseases is essential for the understanding of the pathogenesis. Immune responses against these antigens could be used as biomarkers for diagnosis, prognosis and treatment responses. Knowledge of antigen-specific immune responses in individual patients is also a prerequisite for antigen-based therapies.

RECENT FINDINGS

A proportion of patients with demyelinating disease have antibodies to aquaporin 4 (AQP4) or myelin oligodendrocyte glycoprotein (MOG). Patients with anti-AQP4 have the distinct clinical presentation of neuromyelitis optica (NMO), and these patients often also harbour other autoimmune responses. In contrast, anti-MOG is seen in patients with different disease entities such as childhood multiple sclerosis (MS), acute demyelinating encephalomyelitis (ADEM), anti-AQP4 negative NMO, and optic neuritis, but hardly in adult MS. A number of new candidate autoantigens have been identified and await validation. Antigen-based therapies are mainly aimed at tolerizing T-cell responses against myelin basic protein (MBP) and have shown only modest or no clinical benefit so far.

SUMMARY

Currently, only few patients with demyelinating diseases can be characterized based on their autoantibody profile. The most prominent antigens in this respect are MOG and AQP4. Further research has to focus on the validation of newly discovered antigens as biomarkers.