Mechanisms underlying lesion development and lesion distribution in CNS autoimmunity

The impact of HLA-DRB1 alleles in a Hellenic, Pediatric-Onset Multiple Sclerosis cohort: Implications on clinical and neuroimaging profile

BACKGROUND

Pediatric-Onset Multiple Sclerosis (POMS) is considered a complex disease entity and several genetic, hormonal, and environmental factors have been associated with disease pathogenesis. Linkage studies in Caucasians have consistently suggested the human leukocyte antigen (HLA) polymorphisms, as the genetic locus most strongly linked to MS, with the HLA-DRB1*15:01 allele, being associated with both adult and pediatric MS patients. Here we aim to investigate the prevalence of the HLA-DRB1 alleles among a Hellenic POMS cohort and any possible associations with clinical and imaging disease features.

MATERIALS AND METHODS

100 POMS patients fulfilling the IPMSSG criteria, 168 Adult-Onset MS (AOMS) patients, and 246 Healthy Controls (HCs) have been enrolled. HLA genotyping was performed with a standard low-resolution sequence-specific oligonucleotide (SSO) technique.

RESULTS

POMS patients display a significantly increased HLA-DRB1*03 frequency compared to both HCs [24% vs. 12.6%, OR [95%CI]: 2.19 (1.21-3.97), p=0.016) and AOMS (24% vs. 13.1%, OR [95%CI]: 2.1 (1.1-3.98), p=0.034] respectively. HLA-DRB1*03-carriers display reduced risk for brainstem lesion development (OR [CI 95%]:0.19 (0.06-0.65), p=0.011). A significantly lower frequency of HLA-DRB1*07 (4% vs 13.4%, OR (95% CI): 0.27 (0.09-0.78), p= 0.017) and HLA-DRB1*11 (37% vs 52%, OR [95% CI]: 0.54 (0.34-0.87), p= 0.016) was observed in POMS compared to HCs.

CONCLUSION

The HLA-DRB1*03 allele was associated with a higher risk for POMS, replicating our previous findings, and with a lower risk for brainstem lesion development, a common clinical and neuroimaging feature in POMS, while HLA-DRB1*07 and HLA-DRB1*11 display a protective role. These findings expand the existing knowledge of HLA associations and POMS.

Humanized-Aquaporin-4-Expressing Rat Created by Gene-Editing Technology and Its Use to Clarify the Pathology of Neuromyelitis Optica Spectrum Disorder

Conventional rodent neuromyelitis optica spectrum disorder (NMOSD) models using patient-derived immunoglobulin G (IgG) are potentially affected by the differences between the human and rodent aquaporin-4 (AQP4) extracellular domains (ECDs). We hypothesized that the humanization of AQP4 ECDs would make the rodent model lesions closer to human NMOSD pathology. Humanized-AQP4-expressing (hAQP4) rats were generated using genome-editing technology, and the human AQP4-specific monoclonal antibody (mAb) or six patient-derived IgGs were introduced intraperitoneally into hAQP4 rats and wild-type Lewis (WT) rats after immunization with myelin basic protein and complete Freund's adjuvant. Human AQP4-specific mAb induced astrocyte loss lesions specifically in hAQP4 rats. The patient-derived IgGs also induced NMOSD-like tissue-destructive lesions with AQP4 loss, demyelination, axonal swelling, complement deposition, and marked neutrophil and macrophage/microglia infiltration in hAQP4 rats; however, the difference in AQP4 loss lesion size and infiltrating cells was not significant between hAQP4 and WT rats. The patient-derived IgGs bound to both human and rat AQP4 M23, suggesting their binding to the shared region of human and rat AQP4 ECDs. Anti-AQP4 titers positively correlated with AQP4 loss lesion size and neutrophil and macrophage/microglia infiltration. Considering that patient-derived IgGs vary in binding sites and affinities and some of them may not bind to rodent AQP4, our hAQP4 rat is expected to reproduce NMOSD-like pathology more accurately than WT rats.

In Vitro and Ex Vivo Methodologies for T-Cell Trafficking Through Blood-Brain Barrier After TLR Activation

This chapter describes ex vivo isolation of human T cells and of naïve splenocytes respectively collected from multiple sclerosis patients and healthy controls and experimental autoimmune encephalomyelitis-affected mice. After the magnetic sorting of naïve and activated T helper lymphocytes, we provide details about the cell cultures to measure the interaction with extracellular matrix proteins using standard cell invasion or hand-made in vitro assays, upon different stimuli, through Toll-like receptor(s) ligands, T-cell activators, and cell adhesion molecules modulators. Finally, we describe the methods to harvest and recover T cells to evaluate the properties associated with their trafficking ability.

Granzyme B in circulating CD8+ T cells as a biomarker of immunotherapy effectiveness and disability in neuromyelitis optica spectrum disorders

BACKGROUND AND OBJECTIVE

Neuromyelitis optica spectrum disorders (NMOSD) are chronical inflammatory demyelinating diseases of the central nervous system (CNS) and the underlying mechanism remains unclear. Several recent studies have demonstrated that T cells play a pivotal role in the pathogenesis of NMOSD.In this study, we investigated CD8+ T cell phenotypes and levels of the cytotoxic protein granzyme B (GzmB), as well as their potential clinical application in NMOSD.

METHODS

In this study, 90 peripheral blood samples were collected from 59 NMOSD patients with seropositive anti-aquaporin-4 (AQP4) antibodies and 31 sex- and age-matched healthy donors (HDs). Flow cytometry was used to detect circulating levels of GzmB and CD8+ T cell subpopulations, including naïve (TN, CCD7+CD45RA+), central memory (TCM, CCD7+CD45RA-), effector memory (TEM, CCD7-CD45RA-), terminal differentiation effector memory cells (TEMRA, CCD7-CD45RA+) in both groups. The associations between GzmB levels in CD8+T cells and clinical characteristics of NMOSD were evaluated.

RESULTS

NMOSD patients exhibited significantly decreased proportions of CD8+TN cells and increased proportions of highly differentiated CD8+T cells (TEMRA) compared with HDs. In addition, levels of GzmB in CD8+ T cells were markedly higher in NMOSD patients than in HDs. Moreover, we observed that high proportions of GzmB-expressing CD8+ T cells were more common in patients with a poor response to immunotherapies, and showed a good potential to distinguish poor responders from responders (ACU=0.89). Clinical correlation analysis indicated that high levels of GzmB in CD8+ T cells were not only related to severe disability but also significantly associated with increased serum levels of neurofilament light (NFL) and glial fibrillary acidic protein (GFAP). Multivariate linear regression analyses further suggested that GzmB expression in CD8+ T cells was predominantly associated with disability and immunotherapy effectiveness in NMOSD, independent of the sex, age, and disease phase. Transcription factor T-bet in CD8+ T cells were also significantly elevated in NMOSD and were associated with increasing number of circulating CD8+TEMRA cells and GzmB-expressing CD8+T cells.

CONCLUSIONS

Our study support the involvement of GzmB-expressing CD8+ T cells in the inflammatory response in patients with NMOSD and provide a potential biomarker for disease immunotherapy effectiveness and disability progression.

Transparent Quality Optimization for Machine Learning-Based Regression in Neurology

The clinical monitoring of walking generates enormous amounts of data that contain extremely valuable information. Therefore, machine learning (ML) has rapidly entered the research arena to analyze and make predictions from large heterogeneous datasets. Such data-driven ML-based applications for various domains become increasingly applicable, and thus their software qualities are taken into focus. This work provides a proof of concept for applying state-of-the-art ML technology to predict the distance travelled of the 2-min walk test, an important neurological measurement which is an indicator of walking endurance. A transparent lean approach was emphasized to optimize the results in an explainable way and simultaneously meet the specified software requirements for a generic approach. It is a general-purpose strategy as a fractional−factorial design benchmark combined with standardized quality metrics based on a minimal technology build and a resulting optimized software prototype. Based on 400 training and 100 validation data, the achieved prediction yielded a relative error of 6.1% distributed over multiple experiments with an optimized configuration. The Adadelta algorithm (LR=0.000814, fModelSpread=5, nModelDepth=6, nepoch=1000) performed as the best model, with 90% of the predictions with an absolute error of <15 m. Factors such as gender, age, disease duration, or use of walking aids showed no effect on the relative error. For multiple sclerosis patients with high walking impairment (EDSS Ambulation Score ≥6), the relative difference was significant (n=30; 24.0%; p<0.050). The results show that it is possible to create a transparently working ML prototype for a given medical use case while meeting certain software qualities.

A TLR/CD44 axis regulates T cell trafficking in experimental and human multiple sclerosis

In the pathogenesis of autoimmune disorders, the modulation of leukocytes' trafficking plays a central role, still poorly understood. Here, we focused on the effect of TLR2 ligands in trafficking of T helper cells through reshuffling of CD44 isoforms repertoire. Concurrently, strain background and TLR2 haplotype affected Wnt/β-catenin signaling pathway and expression of splicing factors. During EAE, mCD44 v9- v 10 was specifically enriched in the forebrain and showed an increased ability to bind stably to osteopontin. Similarly, we observed that hCD44 v7 was highly enriched in cells of cerebrospinal fluid from MS patients with active lesions. Moreover, TLRs engagement modulated the composition of CD44 variants also in human T helper cells, supporting the hypothesis that pathogens or commensals, through TLRs, in turn modulate the repertoire of CD44 isoforms, thereby controlling the distribution of lesions in the CNS. The interference with this mechanism(s) represents a potential tool for prevention and treatment of autoimmune relapses and exacerbations.

An In Vitro Model of the Blood-Brain Barrier to Study Alzheimer's Disease: The Role of β-Amyloid and Its Influence on PBMC Infiltration

The blood-brain barrier (BBB) is a highly specialized structure, constituted by endothelial cells that together with astrocytes and pericytes provide a functional interface between the central nervous system and the periphery. Several pathological conditions may affect its functions, and lately BBB involvement in the pathogenesis of Alzheimer's disease has been demonstrated. Both endothelial cells and astrocytes can be differentially affected during the course of the disease. In vitro BBB models present a powerful tool in evaluating the effects that β-amyloid (Aβ), or other pathogenic stimuli, play on the BBB at cellular level. In vitro BBB models derived from human cell sources are rare and not easily implemented. We generated two conditionally immortalized human cell lines, brain microvascular endothelial cells (TY10), and astrocytes (hAST), that, when co-cultured under appropriate conditions, exhibit BBB-like characteristics. This model allowed us to evaluate the transmigration of peripheral blood mononuclear cells (PBMCs) through the in vitro barrier exposed to Aβ and the role played by astrocytes in the modulation of this phenomenon. We describe here the methodology used in our lab to set up our in vitro model of the BBB and to carry out a PBMC transmigration assay.

Automated Analysis of the Two-Minute Walk Test in Clinical Practice Using Accelerometer Data

One of the core problems for people with multiple sclerosis (pwMS) is the impairment of their ability to walk, which can be severely restrictive in everyday life. Therefore, monitoring of ambulatory function is of great importance to be able to effectively counteract disease progression. An extensive gait analysis, such as the Dresden protocol for multidimensional walking assessment, covers several facets of walking impairment including a 2-min walk test, in which the distance taken by the patient in two minutes is measured by an odometer. Using this approach, it is questionable how precise the measuring methods are at recording the distance traveled. In this project, we investigate whether the current measurement can be replaced by a digital measurement method based on accelerometers (six Opal sensors from the Mobility Lab system) that are attached to the patient’s body. We developed two algorithms using these data and compared the validity of these approaches using the results from 2-min walk tests from 562 pwMS that were collected with a gold-standard odometer. In 48.4% of pwMS, we detected an average relative measurement error of less than 5%, while results from 25.8% of the pwMS showed a relative measurement error of up to 10%. The algorithm had difficulties correctly calculating the walking distances in another 25.8% of pwMS; these results showed a measurement error of more than 20%. A main reason for this moderate performance was the variety of pathologically altered gait patterns in pwMS that may complicate the step detection. Overall, both algorithms achieved favorable levels of agreement (r = 0.884 and r = 0.980) with the odometer. Finally, we present suggestions for improvement of the measurement system to be implemented in the future.

Neuromyelitis optica spectrum disorders: from pathophysiology to therapeutic strategies

Neuromyelitis optica (NMO) is a chronic inflammatory autoimmune disease of the central nervous system (CNS) characterized by acute optic neuritis (ON) and transverse myelitis (TM). NMO is caused by a pathogenic serum IgG antibody against the water channel aquoporin 4 (AQP4) in the majority of patients. AQP4-antibody (AQP4-ab) presence is highly specific, and differentiates NMO from multiple sclerosis. It binds to AQP4 channels on astrocytes, triggering activation of the classical complement cascade, causing granulocyte, eosinophil, and lymphocyte infiltration, culminating in injury first to astrocyte, then oligodendrocytes followed by demyelination and neuronal loss. NMO spectrum disorder (NMOSD) has recently been defined and stratified based on AQP4-ab serology status. Most NMOSD patients experience severe relapses leading to permanent neurologic disability, making suppression of relapse frequency and severity, the primary objective in disease management. The most common treatments used for relapses are steroids and plasma exchange.Currently, long-term NMOSD relapse prevention includes off-label use of immunosuppressants, particularly rituximab. In the last 2 years however, three pivotal clinical trials have expanded the spectrum of drugs available for NMOSD patients. Phase III studies have shown significant relapse reduction compared to placebo in AQP4-ab-positive patients treated with satralizumab, an interleukin-6 receptor (IL-6R) inhibitor, inebilizumab, an antibody against CD19⁺ B cells; and eculizumab, an antibody blocking the C5 component of complement. In light of the new evidence on NMOSD pathophysiology and of preliminary results from ongoing trials with new drugs, we present this descriptive review, highlighting promising treatment modalities as well as auspicious preclinical and clinical studies.

CNS autoimmunity in children: An unwanted wrinkle in a smooth narrative

The emerging paradigm of childhood autoimmune neurological disorders has exploded in recent times due to reliable diagnostic methods and their ease of availability, well-defined diagnostic criteria, and universal awareness about these disorders. The most important aspect of these disorders is a considerable recovery in response to early targeted immunotherapy. If left untreated and/or ill-treated, these can lead to mortality or lifelong morbidity. Autoantibodies can target any part of the central nervous system (CNS), ranging from superficial structures like myelin to deep intracellular ion channels like voltage-gated potassium channels, resulting in contrasting and at times overlapping symptomatology. Though neuroimaging characteristics and serological tests confirm these disorders' diagnosis, it is essential to suspect them clinically and start management before the reports are available for minimizing morbidity and mortality. In the pediatric age group, several metabolic conditions, like mitochondrial disorders and enzyme deficiencies like HMG-CoA-lyase deficiency, can develop neuroimaging patterns similar to those seen in childhood CNS autoimmune disorders and may also show a favorable response to steroids in acute phases. Hence, the clinician must suspect and work up the index patient appropriately. Here, we briefly discuss the pathophysiology, clinical clues, and potential therapeutic targets related to pediatric CNS autoimmune disorders.

Protective effect of the sphingosine-1 phosphate receptor agonist siponimod on disrupted blood brain barrier function

Sphingosine 1 phosphate (S1P) is a bioactive sphingolipid that exerts several functions in physiological and pathological conditions. The modulation of one of its receptors, S1P1, plays an important role in the egress of lymphocytes from lymph nodes and is a useful target in multiple sclerosis (MS) treatment. A new drug, siponimod (BAF-312) has been recently approved for the treatment of secondary progressive MS and has affinity for two S1P receptors, S1P1 and S1P5. The two receptors are expressed by endothelial cells that, as components of the blood-brain barrier (BBB), prevent the access of solutes and lymphocytes into the central nervous system, function often compromised in MS. Using an in vitro BBB model exposed to inflammatory cytokines (TNFα and IFNγ, 5 UI and 10 UI respectively), we evaluated the effects of BAF-312 (100 nM) on expression and function of endothelial tight junctional proteins (Zo-1 and claudin-5), regulation of transendothelial electrical resistance (TEER) and permeability to FITC-conjugated dextran. Zo-1 expression, as well as TEER values, were promptly recovered (24 h) when both S1P1 and S1P5 were activated by BAF-312. In contrast, at this time point, activation of S1P5 with the selective agonist UC-42-WP04 (300 nM) or with BAF-312, under blockade of S1P1 with the selective antagonist NIBR-0213 (1 μM), resulted in recovery of expression and localization of claudin-5 and reduction of TNFα/INFγ-induced expression of metalloproteinase 9. Only after a prolonged BAF-312 exposure (48 h), S1P1 was involved through activation of the PI3K/Akt pathway. The PI3K inhibitor LY294002 (10 µM) prevented in fact the effects of BAF-312 on all the parameters examined. In conclusion, BAF-312, by modulating both S1P1 and S1P5, may strengthen BBB properties, thus providing additional effects in the treatment of MS.

CD8+ T cell subpopulations and pro-inflammatory cytokines in neuromyelitis optica spectrum disorder

Objective

Our study aimed to investigate circulating CD8⁺ T cell subpopulations and pro‐inflammatory cytokines in the neuromyelitis optica spectrum disorder (NMOSD).

Methods

A total of 121 peripheral blood samples were obtained from 57 patients with NMOSD, 34 patients with multiple sclerosis (MS), and 30 sex‐ and age‐matched healthy controls (HCs) for detection of CD8⁺ T cell subpopulations, including phenotypes of naïve (T_N, CD62L^hiCD45RO^‐), effector/memory (T_E/M, CD62L^loCD45RO⁺), memory precursor (T_MP, CD127^hiKLRG1^lo), and short lived effector (T_SLEC, CD127^loKLRG1^hi). In addition, 36 samples from 18 NMOSD, 12 MS, and 6 sex‐ and age‐matched HCs for detecting pro‐inflammatory cytokines (IFNγ and TNFα) using flow cytometry.

Results

Compared with HCs, we found significantly reduced CD8⁺ T_N and increased CD8⁺ T_E/M in both NMOSD and MS，while decreased CD8⁺ T_MP was only observed in NMOSD. Patients treated with immunotherapy were associated with increased CD8⁺ T_N and decreased CD8⁺ T_E/M in NMOSD. Moreover NMOSD cohort showed significant higher proportions of IFNγ⁺CD8⁺ T cells and proportions of TNFα⁺CD8⁺ T cells than HC and MS cohorts. On the contrary, obviously decreased IFNγ and TNFα were found in NMOSD patients treated with immunotherapy. Furthermore, Multivariate linear regression analyses revealed that age was negatively correlated with CD8⁺ T_N and T_MP, and positively associated with T_SLEC; however, sex, EDSS scores and disease phase were not significantly associated with CD8⁺ T subpopulations.

Interpretation

This current study provides an evidence that circulating CD8⁺ T cell with abnormal subpopulations and increased pro‐inflammatory were associated with pathogenesis of autoimmune demyelinating disease of CNS, especially in NMOSD.

The Dresden Protocol for Multidimensional Walking Assessment (DMWA) in Clinical Practice

Walking impairments represent one of the most debilitating symptom areas for people with multiple sclerosis (MS). It is important to detect even slightest walking impairments in order to start and optimize necessary interventions in time to counteract further progression of the disability. For this reason, a regular monitoring through gait analysis is highly necessary. At advanced stages of MS with significant walking impairment, this assessment is also necessary to optimize symptomatic treatment, choose the most suitable walking aid and plan individualized rehabilitation. In clinical practice, walking impairment is only assessed at higher levels of the disease using e.g., the Expanded Disability Status Scale (EDSS). In contrast to the EDSS, standardized functional tests such as walking speed, walking endurance and balance as well as walking quality and gait-related patient-reported outcomes allow a more holistic and sensitive assessment of walking impairment. In recent years, the MS Center Dresden has established a standardized monitoring procedure for the routine multidimensional assessment of gait and balance disorders. In the following protocol, we present the techniques and procedures for the analysis of gait and balance of people with MS at the MS Center Dresden. Patients are assessed with a multidimensional gait analysis at least once a year. This enables long-term monitoring of walking impairment, which allows early active intervention regarding further progression of disease and improves the current standard clinical practice.

Correlation between serum levels of endothelin-1 and disease severity in patients with neuromyelitis optica spectrum disorders

AIMS

Neuromyelitis optica spectrum disorders (NMOSD) are aquaporin-4 antibody-mediated diseases of the central nervous system. Endothelin-1 (ET-1) is an inflammatory cytokine released by vascular endothelial cells and activated astrocytes. Previous studies have reported the aberrant expressions of cytokines/chemokines in patients diagnosed with NMOSD. However, the serum levels of ET-1 in NMOSD patients remain unknown. The purpose of this study was to measure the serum levels of ET-1 and other immune-related cytokines/chemokines in patients with NMOSD, and to investigate the correlation between serum ET-1 levels and clinical characteristics of NMOSD.

METHODS

Thirty-eight patients with NMOSD and twenty-eight healthy controls (HCs) were recruited in this study. The serum concentrations of ET-1 and other cytokines/chemokines were measured, and their correlations to the clinical features of patients with NMOSD were analyzed.

RESULTS

The serum levels of ET-1 in patients with NMOSD were significantly higher than those in HCs (P =  0.0001). The serum concentrations of ET-1 were positively correlated with the Expanded Disability Status Scale score (r = 0.428, P = 0.0183). High-dose intravenous methylprednisolone treatment significantly reduced the levels of ET-1 and interleukin (IL)-6 in blood, but significantly increased the serum concentrations of IL-10 in NMOSD patients. No correlations were found between serum ET-1 levels and the concentrations of other cytokines/chemokines in these patients.

CONCLUSION

ET-1 and IL-6 might exert pro-inflammatory effects in the pathogenesis of NMOSD, whereas IL-10 played an anti-inflammatory role in this process. ET-1 might be a potential biomarker for predicting the severity of NMOSD. However, the serum levels of ET-1 were not correlated with the changes of other cytokines/chemokines in patients with NMOSD. The involvement of ET-1 in the development of NMOSD needs to be further studied.

FoxP3 deficiency causes no inflammation or neurodegeneration in the murine brain

Regulatory T cells (Treg) maintain immunological self-tolerance and their functional or numerical deficits are associated with progression of several neurological diseases. We examined the effects of Treg absence on the structure and integrity of the unchallenged murine brain. When compared to control, Treg-deficient FoxP3sf mutant mice showed no differences in brain size, myelin amount and oligodendrocyte numbers. FoxP3sf strain displayed no variations in quantity of neurons and astrocytes, whereas microglia numbers were slightly reduced. We demonstrate lack of neuroinflammation and parenchymal responses in the brains of Treg-deficient mice, suggesting a minor Treg role in absence of blood-brain barrier breakdown.

Therapeutic Plasma Exchange in Multiple Sclerosis and Autoimmune Encephalitis: a Comparative Study of Indication, Efficacy and Safety

Therapeutic plasma exchange (TPE) is a well-established method of treatment for steroid-refractory relapses in multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD). Little is known about indications and clinical responses to TPE in autoimmune encephalitis and other immune-mediated disorders of the central nervous system (CNS). We performed a retrospective chart review of patients with immune-mediated disorders of the CNS undergoing TPE at our tertiary care center between 2003 and 2015. The response to TPE within a 3- to 6-month follow-up was scored with an established rating system. We identified 40 patients including 21 patients with multiple sclerosis (MS, 52.5%), 12 with autoimmune encephalitis (AE, 30%), and 7 with other immune-mediated CNS disorders (17.5%). Among patients with AE, eight patients had definite AE (Immunolobulin G for N-methyl-D-aspartate receptor n = 4, Leucine-rich, glioma inactivated 1 n = 2, Ma 2 n = 1, and Alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid n = 1). Intravenous immunoglobulins had been given prior to TPE in all but one patient with AE, and indications were dominated by acute psychosis and epileptic seizures. While TPE has a distinct place in the treatment sequence of different immune-mediated CNS disorders, we found consistent efficacy and safety. Further research should be directed toward alternative management strategies in non-responders.

Confusion, dissociation and bizarre behaviour as the onset of an early Susac syndrome

A 47-year-old woman presented an episode of confusion and disorientation. According to remarkable psychiatric records, she had been treated for major depression and obsessive-compulsive disorder; however, no other relevant background was known. After preliminary examinations, blood analysis and neurological tests were unspecific and inconclusive. Therefore, the case was treated as a possible psychiatric episode related to her previous psychiatric disorders. However, due to the atypical presentation of the case, a cerebral MRI was performed, which demonstrated multiple central lesions of the corpus callosum ('snowball lesions'), as well as several supratentorial white matter lesions. As a result of the follow-up of the case, sensorineural hearing loss and branch retinal artery were detected, which concluded in the classic triad and the confirmation of the diagnosis of a Susac syndrome.

Potential mechanisms of action related to the efficacy and safety of cladribine

Oral cladribine is a novel treatment for relapsing multiple sclerosis (MS). This appears to be a semi-selective immune-reconstitution therapy that induces long-term therapy from short treatment cycles. It has a relatively good safety profile that currently does not require extensive monitoring associated with some continuous immunosuppressive and relatively non-selective immune reconstitution therapies. The efficacy and safety of cladribine relates to its particular physicochemical properties, the function of the lymphocyte subsets that are selectively targeted by the drug and the repopulation kinetics of these subsets. As such, there is marked and long-term depletion of memory B cell subsets, which probably relates to the therapeutic efficacy. This is also coupled with a more limited, but likewise long-term, depletion of CD4 T subsets. There is limited depletion of cells of the innate immune system and modest effects on CD8 and probably plasma cells, which provide immediate and durable protection from infection. Targeting of CD4 T regulatory cells, CD8 T suppressor cells and regulatory B cell subsets appears more limited as these populations recover rapidly and so repopulating pathogenic cells re-emerge into a regulatory environment. This appears to lead to re-establishment of immune-tolerance that produces long-term control of MS. Although this hypothesis contains a number of unknown details, it is based on knowledge about the biology of cladribine, basic immunology and the effects of other high-efficacy B and T cell depleting agents that exhibit stereotyped repopulation behaviours. These concepts are relatively simple to interrogate, and can be modified as new knowledge about the durability of disease control and safety with cladribine emerges.

The Emerging Role of Neutrophil Granulocytes in Multiple Sclerosis

Multiple sclerosis (MS) is a demyelinating disease of the central nervous system with a strong autoimmune, neurodegenerative, and neuroinflammatory component. Most of the common disease modifying treatments (DMTs) for MS modulate the immune response targeting disease associated T and B cells and while none directly target neutrophils, several DMTs do impact their abundance or function. The role of neutrophils in MS remains unknown and research is ongoing to better understand the phenotype, function, and contribution of neutrophils to both disease onset and stage of disease. Here we summarize the current state of knowledge of neutrophils and their function in MS, including in the rodent based MS model, and we discuss the potential effects of current treatments on these functions. We propose that neutrophils are likely to participate in MS pathogenesis and their abundance and function warrant monitoring in MS.

The Cytotoxicity of Epsilon Toxin from Clostridium perfringens on Lymphocytes Is Mediated by MAL Protein Expression

Epsilon toxin (Etx) from Clostridium perfringens is a pore-forming protein that crosses the blood-brain barrier, binds to myelin, and, hence, has been suggested to be a putative agent for the onset of multiple sclerosis, a demyelinating neuroinflammatory disease. Recently, myelin and lymphocyte (MAL) protein has been identified to be a key protein in the cytotoxic effect of Etx; however, the association of Etx with the immune system remains a central question. Here, we show that Etx selectively recognizes and kills only human cell lines expressing MAL protein through a direct Etx-MAL protein interaction. Experiments on lymphocytic cell lines revealed that MAL protein-expressing T cells, but not B cells, are sensitive to Etx and reveal that the toxin may be used as a molecular tool to distinguish subpopulations of lymphocytes. The overall results open the door to investigation of the role of Etx and Clostridium perfringens on inflammatory and autoimmune diseases like multiple sclerosis.

Olfactory Dysfunction in CNS Neuroimmunological Disorders: a Review

Olfactory dysfunction is deeply associated with quality of human life in the aging population. Olfactory dysfunction is an occasional presymptomatic sign of neuroimmunological multiple sclerosis, neuromyelitis optica, and systemic lupus erythematosus. Olfaction is initially processed by olfactory receptor cells that capture odor molecules, and the signals are transmitted to the glomeruli in the olfactory bulbs via olfactory nerves and processed in the primary olfactory cortex in the brain. Damage to either the olfactory receptor cells or the olfactory bulb and primary olfactory cortex may influence olfactory functioning. A close link between neuroimmunological disorders and olfactory dysfunction has been reported in patients and animal models. This review summarizes the literature data concerning olfactory dysfunction in autoimmune diseases including multiple sclerosis, neuromyelitis optica, and systemic lupus erythematosus; animal models thereof; and inflammation in the olfactory bulb.