Neuropathology in multiple sclerosis: new concepts

Prognostic significance of paramagnetic rim lesions in multiple sclerosis: A systematic review

The diagnostic potential of paramagnetic rim lesions (PRLs) has been previously established; however, the prognostic significance of these lesions has not previously been consistently described. This study aimed to establish the prognostic role of PRLs in MS with respect to the Expanded Disability Status Scale (EDSS) and rates of disability progression. Databases of PubMed, EMBASE, Scopus and reference lists of selected articles were searched up to 29/04/2023. The review was conducted in accordance with PRISMA guidelines and was registered prospectively on PROSPERO (CRD42023422052). 7 studies were included in the final review. All of the eligible studies found that patients with PRLs tend to have higher baseline EDSS scores. Longitudinal assessments revealed greater EDSS progression in patients with PRLs over time in most studies. However, the effect of location of PRLs within the central nervous system were not assessed across the studies. Only one study investigated progression independent of relapse activity (PIRA) and showed that this clinical entity occurred in a greater proportion in patients with PRLs. This review supports PRLs as a predictor of EDSS progression. This measure has widespread applicability, however further multicentre studies are needed. Future research should explore the impact of PRLs on silent disability, PIRA, take into account different MS phenotypes and the topography of PRLs in prognosis.

The Therapeutic Potential and Molecular Mechanisms Underlying the Neuroprotective Effects of Sativex® - A Cannabis-derived Spray

Sativex is a cannabis-based medicine that comes in the form of an oromucosal spray. It contains equal amounts of Δ9-tetrahydrocannabinol and cannabidiol, two compounds derived from cannabis plants. Sativex has been shown to have positive effects on symptoms of amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS), and sleep disorders. It also has analgesic, antiinflammatory, antitumoral, and neuroprotective properties, which make it a potential treatment option for other neurological disorders. The article reviews the results of recent preclinical and clinical studies that support the therapeutic potential of Sativex and the molecular mechanisms behind its neuroprotective benefits in various neurological disorders. The article also discusses the possible advantages and disadvantages of using Sativex as a neurotherapeutic agent, such as its safety, efficacy, availability, and legal status.

MR volumetry in detection of brain atrophic changes in MS patients and its implication on disease prognosis: retrospective study

Background

Multiple sclerosis is a chronic demyelinating disease of the central nervous system. It may lead to disability and cognitive impairment. Our study aimed at evaluation of the role of MR volumetry technique in detection of brain atrophic changes in patients with multiple sclerosis and its impact on disease prognosis.

Results

This study was carried out on thirty healthy control with mean age 26.23 years and thirty patients with remitting relapsing multiple sclerosis, with a mean age of 28.18 years. Patients with multiple sclerosis were distributed across six subgroups based on the z-score cut-off of − 1.96 for regional and whole brain atrophy. We found that 2 patients (6.6%) showed no thalamic or brain atrophy, 28 patients (93.3%) showed whole brain atrophy only and 10 patients (33.3%) showed both, thalamic and BP atrophy. No patients showed only thalamic atrohy, 4 patients showed whole brain atrophy with other structure atrophy rather than thalamus (13.3%), 10 patients with whole brain and more than one structure atrophy (33.3%). Relation between subgroups and degree of increase in the Expanded Disability Status Scale (EDSS) as well as presence of cognitive decline were assessed. No significant relation were found between RRMS patients subgroups with whole brain atrophy, subgroup with isolated thalamic atrophy or subgroup with multiple structure atrophy and increase of EDSS or cognitive decline.

Conclusion

We found that MRI volumetry is a very useful technique in the assessment of the atrophic changes that occur as a consequence of multiple sclerosis affecting the whole brain, deep grey matter as well as corpus callosum. Although our study did not prove significant relation between presence of brain atrophic changes and disability or cognitive impairment, presence of atrophy warrants careful clinical evaluation of those patients to detect any possible further progression of disability or cognitive decline.

Effect of eight weeks respiratory muscle training on respiratory capacity, functional capacity and quality of life on subjects with mild to moderate relapsing-remitting multiple sclerosis: A single-blinded randomized controlled trial

BACKGROUND

Multiple Sclerosis (MS) is a chronic inflammatory disease of the nervous system leading to muscle weakness, including the respiratory muscles that cause pulmonary complications, impair functional capacity, increased fatigue, and as a result decreases the quality of life.

AIM

The purpose of the present study is to examine the influence of 8 weeks of respiratory muscle training (RMT) on pulmonary function and respiratory muscle strength in MS patients.

METHODS

The present study was a single-blind, randomized controlled trial that was conducted on 36 (27 Female, 9 Male) relapsing-remitting MS patients who were definitively diagnosed by a neurologist and randomly were divided into intervention and control groups. Both groups were educated on lifestyle modification with an emphasis on regular physical activity. In addition, the intervention group was prescribed eight weeks of respiratory muscle training with a threshold resistance device, daily, twice a day for three sets of 15 repetitions per set. Maximal expiratory pressure (PImax), maximal expiratory pressure (PEmax), spirometric indices, functional tests (six-minute walk test, timed up and go test), fatigue questionnaire, and questionnaire of quality of life were assessed before and after trials.

RESULTS

A total of 36 patients (75% female; mean age 38.00(8.86) years; BMI 26.56(2.64) kg/m²) were included in the study. The strength of inspiratory and expiratory muscles, respiratory function, fatigue, and quality of life were significantly improved in the intervention group (p<0.005). In addition, there was a significant improvement in the rate of fatigue and quality of life in all their dimensions (p<0.005). Only in the six-minute walk test, no significant improvement was seen in the intervention group compared to the control group (p = 0.262).

CONCLUSION

Findings could help therapists to provide MS patients with more effective respiratory muscle training protocols to maximize the benefits of rehabilitation.

Chronic experimental autoimmune encephalomyelitis is an excellent model to study neuroaxonal degeneration in multiple sclerosis

Animal models of multiple sclerosis (MS), specifically experimental autoimmune encephalomyelitis (EAE), have been used extensively to develop anti-inflammatory treatments. However, the similarity between MS and one particular EAE model does not end at inflammation. MS and chronic EAE induced in C57BL/6 mice using myelin oligodendrocyte glycoprotein (MOG) peptide 35-55 share many neuropathologies. Beyond both having white matter lesions in spinal cord, both also have widespread neuropathology in the cerebral cortex, hippocampus, thalamus, striatum, cerebellum, and retina/optic nerve. In this review, we compare neuropathologies in each of these structures in MS with chronic EAE in C57BL/6 mice, and find evidence that this EAE model is well suited to study neuroaxonal degeneration in MS.

A Critical Review of the Role of the Cannabinoid Compounds Δ9-Tetrahydrocannabinol (Δ9-THC) and Cannabidiol (CBD) and their Combination in Multiple Sclerosis Treatment

Many people with MS (pwMS) use unregulated cannabis or cannabis products to treat the symptoms associated with the disease. In line with this, Sativex, a synthetic combination of cannabidiol (CBD) and Δ⁹-tetrahydrocannabinol (Δ⁹-THC) has been approved to treat symptoms of spasticity. In animals, CBD is effective in reducing the amounts of T-cell infiltrates in the spinal cord, suggesting CBD has anti-inflammatory properties. By doing this, CBD has shown to delay symptom onset in animal models of multiple sclerosis and slow disease progression. Importantly, combinations of CBD and Δ⁹-THC appear more effective in treating animal models of multiple sclerosis. While CBD reduces the amounts of cell infiltrates in the spinal cord, Δ⁹-THC reduces scores of spasticity. In human studies, the results are less encouraging and conflict with the findings in animals. Drugs which deliver a combination of Δ⁹-THC and CBD in a 1:1 ratio appear to be only moderately effective in reducing spasticity scores, but appear to be almost as effective as current front-line treatments and cause less severe side effects than other treatments, such as baclofen (a GABA-B receptor agonist) and tizanidine (an α2 adrenergic receptor agonist). The findings of the studies reviewed suggest that cannabinoids may help treat neuropathic pain in pwMS as an add-on therapy to already established pain treatments. It is important to note that treatment with cannabinoid compounds may cause significant cognitive dysfunction. Long term double-blind placebo studies are greatly needed to further our understanding of the role of cannabinoids in multiple sclerosis treatment.

Immune-mediated genesis of multiple sclerosis

Multiple sclerosis (MS) is widely acknowledged to be an autoimmune disease affecting the neuronal myelin structure of the CNS. Autoantigens recognized as the target of this autoimmune process are: myelin basal protein, anti-proteolipid protein, antimyelin-associated glycoprotein and antimyelin-based oligodendrocytic basic protein. Ample evidence supports the idea of a dysregulation of immunological tolerance towards self-antigens of neuronal myelin structure triggered by one or more viral or bacterial microbial agents in predisposed HLA gene subjects. Genetic predisposition to MS has been highlighted by numerous studies associating the disease to specific HLA haplotypes. Moreover, a wide range of evidence supports the fact that MS may be consequence of one or more viral or bacterial infections such as measles virus, EBV, HHV6, HZV, Chlamydia pneumoniae, Helicobacter Pylori, and other microbial agents. Microbiota elements also seems to have a role on the determinism of the disease as a pathogenic or protective factor. The autoimmune pathogenetic process could arise when a molecular mimicry between a foreign microbial antigen and an auto-antigen occurs in an HLA gene subject competent for that particular antigen. The antigen-presenting cells in this case would induce the activation of a specific Th clone causing a cross-reaction between a foreign antigen and an autoantigen resulting in an autoimmune response.

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A multifactorial ethiopathogenetic model based on immunomediation is a reliable hypothesis for multiple sclerosis.

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Evidence found in the scientific literature makes it possible to reconstruct this etiopathogenetic hypothesis for MS.

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HLA gene predisposition, correlation with infections, molecular mimicry and other immunological data are reported.

Friend, Foe or Both? Immune Activity in Alzheimer's Disease

Alzheimer's disease (AD) is marked by the presence of amyloid beta (Aβ) plaques, neurofibrillary tangles (NFT), neuronal death and synaptic loss, and inflammation in the brain. AD research has, in large part, been dedicated to the understanding of Aβ and NFT deposition as well as to the pharmacological reduction of these hallmarks. However, recent GWAS data indicates neuroinflammation plays a critical role in AD development, thereby redirecting research efforts toward unveiling the complexities of AD-associated neuroinflammation. It is clear that the innate immune system is intimately associated with AD progression, however, the specific roles of glia and neuroinflammation in AD pathology remain to be described. Moreover, inflammatory processes have largely been painted as detrimental to AD pathology, when in fact, many immune mechanisms such as phagocytosis aid in the reduction of AD pathologies. In this review, we aim to outline the delicate balance between the beneficial and detrimental aspects of immune activation in AD as a more thorough understanding of these processes is critical to development of effective therapeutics for AD.

TMEM10 Promotes Oligodendrocyte Differentiation and is Expressed by Oligodendrocytes in Human Remyelinating Multiple Sclerosis Plaques

Oligodendrocyte precursor cells (OPCs) differentiate during postnatal development into myelin-forming oligodendrocytes, in a process distinguished by substantial changes in morphology and the onset of myelin gene expression. A mammalian-specific CNS myelin gene, tmem10, also called Opalin, encodes a type 1 transmembrane protein that is highly upregulated during early stages of OPC differentiation; however, a function for TMEM10 has not yet been identified. Here, consistent with previous studies, we detect TMEM10 protein in mouse brain beginning at ~P10 and show that protein levels continue to increase as oligodendrocytes differentiate and myelinate axons in vivo. We show that constitutive TMEM10 overexpression in the Oli-neu oligodendroglial cell line promotes the expression of the myelin-associated genes MAG, CNP and CGT, whereas TMEM10 knock down in primary OPCs reduces CNP mRNA expression and decreases the percentage of MBP-positive oligodendrocytes that differentiate in vitro. Ectopic TMEM10 expression evokes an increase in process extension and branching, and blocking endogenous TMEM10 expression results in oligodendrocytes with abnormal cell morphology. These findings may have implications for human demyelinating disorders, as oligodendrocytes expressing TMEM10 are detected in human remyelinating multiple sclerosis lesions. Together, our findings provide evidence that TMEM10 promotes oligodendrocyte terminal differentiation and may represent a novel target to promote remyelination in demyelinating disorders.

Clinical pharmacology of alemtuzumab, an anti-CD52 immunomodulator, in multiple sclerosis

Alemtuzumab, a humanized anti‐CD52 monoclonal antibody, is approved for treatment of relapsing multiple sclerosis (MS). In the Phase II/III trials, patients received 12 or 24 mg/day of alemtuzumab in two treatment courses (5 days for course 1 and 3 days for course 2), 12 months apart. Serum concentrations of alemtuzumab peaked on the last day of dosing in each course and mostly fell below the limit of quantitation by day 30. Alemtuzumab rapidly depleted circulating T and B lymphocytes, with the lowest observed values occurring within days. Lymphocytes repopulated over time, with B cell recovery usually complete within 6 months. T lymphocytes recovered more slowly and generally did not return to baseline by 12 months post‐treatment. Approximately 40 and 80% of patients had total lymphocyte counts, reaching the lower limit of normal by 6 and 12 months after each course, respectively. The clearance of alemtuzumab is dependent on circulating lymphocyte count. A majority of treated patients tested positive for anti‐alemtuzumab antibodies, including inhibitory antibodies, during the 2‐year studies, and a higher proportion of patients tested positive in course 2 than in course 1. The presence of anti‐alemtuzumab antibody appeared to be associated with slower clearance of alemtuzumab from the circulation but had no impact on the pharmacodynamics. No effects of age, race or gender on the pharmacokinetics or pharmacodynamics were observed. Together, the pharmacokinetics, pharmacodynamics and immunogenicity results support the continued development and use of alemtuzumab for the treatment of MS, and probably explain its sustained effects beyond the dosing interval.

Axonal loss in the multiple sclerosis spinal cord revisited

Preventing chronic disease deterioration is an unmet need in people with multiple sclerosis, where axonal loss is considered a key substrate of disability. Clinically, chronic multiple sclerosis often presents as progressive myelopathy. Spinal cord cross-sectional area (CSA) assessed using MRI predicts increasing disability and has, by inference, been proposed as an indirect index of axonal degeneration. However, the association between CSA and axonal loss, and their correlation with demyelination, have never been systematically investigated using human post mortem tissue. We extensively sampled spinal cords of seven women and six men with multiple sclerosis (mean disease duration= 29 years) and five healthy controls to quantify axonal density and its association with demyelination and CSA. 396 tissue blocks were embedded in paraffin and immuno-stained for myelin basic protein and phosphorylated neurofilaments. Measurements included total CSA, areas of (i) lateral cortico-spinal tracts, (ii) gray matter, (iii) white matter, (iv) demyelination, and the number of axons within the lateral cortico-spinal tracts. Linear mixed models were used to analyze relationships. In multiple sclerosis CSA reduction at cervical, thoracic and lumbar levels ranged between 19 and 24% with white (19-24%) and gray (17-21%) matter atrophy contributing equally across levels. Axonal density in multiple sclerosis was lower by 57-62% across all levels and affected all fibers regardless of diameter. Demyelination affected 24-48% of the gray matter, most extensively at the thoracic level, and 11-13% of the white matter, with no significant differences across levels. Disease duration was associated with reduced axonal density, however not with any area index. Significant association was detected between focal demyelination and decreased axonal density. In conclusion, over nearly 30 years multiple sclerosis reduces axonal density by 60% throughout the spinal cord. Spinal cord cross sectional area, reduced by about 20%, appears to be a poor predictor of axonal density.

Fractional anisotropy of white matter, disability and blood iron parameters in multiple sclerosis

Multiple sclerosis (MS) is a disorder related to myelin damage, which can be investigated by neuroimaging techniques such as fractional anisotropy (FA), a measure of microstructural white matter properties. The objectives of this study were to investigate (1) the relationship between FA and disability using an extremes of outcome approach, and (2) whether blood iron parameters were associated with FA and/or disability. Patients diagnosed with MS (n = 107; 14 males and 93 females) had iron parameter tests and disability determinations using the Expanded Disability Status Scale (EDSS). FA was recorded in 48 white matter tracts in 11 of the female patients with MS and 12 female controls.

RESULTS

In patients with high disability scores the mean FA was significantly lower (0.34 ± 0.067) than in the control group (0.45 ± 0.036; p = 0.04), while patients with low disability had mean FA values (0.44 ± 0.014) similar to controls (p = 0.5). Positive associations were found between FA and the iron parameters serum iron, ferritin and percentage transferrin saturation (%Tfsat) in all the white matter tracts. For % Tfsat, the associations were highly significant in 14 tracts (p < 0.01; r-values 0.74-0.84) and p < 0.001 (r = 0.83) in the superior fronto occipital fasciculus (LH). In the whole patient group a trend was found towards an inverse association between the EDSS and the %Tfsat (r = -0.26, p = 0.05) after excluding male gender and smoking as confounders, suggesting reduced disability in the presence of higher blood iron parameters. Additionally, significant inverse associations between disease duration and haemoglobin (p = 0.04) as well as %Tfsat (p = 0.02) suggested that patients with MS may experience a decrease in blood iron concentrations over time.

Molecular pathology of Multiple Sclerosis lesions reveals a heterogeneous expression pattern of genes involved in oligodendrogliogenesis

Little is known about the decisive molecular factors that regulate lesion remyelination in Multiple Sclerosis. To identify such factors, we performed a differential gene expression analysis of normal appearing white matter (NAWM), active, remyelinating, and inactive demyelinated lesions. As expected, many genes involved in inflammatory processes were detected to be differentially regulated between these tissue types. Among them, we found an increased expression of members of the STAT6 pathway such as STAT6, IL4 and IL4R in active, remyelinated and inactive demyelinated lesions. This suggests that a protective, anti-inflammatory reaction, as already reported to be present in MS NAWM, is further enhanced in lesion tissues. Focusing on genes influencing oligodendrogliogenesis, we found a decreased expression of NKX2-2 in active, remyelinated and inactive demyelinated lesions, whereas SOX10 was downregulated in inactive demyelinated lesions, when compared to NAWM. Simultaneously, CXCL12 (SDF1) expression was strongly increased in active, remyelinated and inactive demyelinated lesions, but increased expression of the IGF1 and IGF2 genes was found in inactive demyelinated lesions. This demonstrates that, in principle, expression of genes promoting oligodendrogliogenesis occurs in MS lesion tissue - even in inactive demyelinated lesions. In contrast, oligodendrogenesis inhibiting genes such as JAG1 were also expressed at higher levels in inactive demyelinated lesions. Both, oligodendrogliogenesis promoting as well as inhibiting genes are expressed in all lesion tissues. However, no clear promoting or inhibiting expression pattern could be detected in any of the different types of lesioned tissues. This might reflect the heterogeneity of lesion development in MS patients, both in terms of mechanisms and temporal differences.

Cytokine and chemokine alterations in tissue, CSF, and plasma in early presymptomatic phase of experimental allergic encephalomyelitis (EAE), in a rat model of multiple sclerosis

BACKGROUND

Experimental allergic encephalomyelitis (EAE) is the most commonly used experimental animal model for human multiple sclerosis (MS) that has been used so far to study the acute and remission-relapsing phases of the disease. Despite the vast literature on neuroinflammation onset and progression in EAE, important questions are still open regarding in particular the early asymptomatic phase between immunization and clinical onset.

METHODS

In this study, we performed a time-course investigation of neuroinflammation and demyelination biomarkers in the spinal cord (SC), cerebrospinal fluid (CSF), and blood in EAE induced in dark agouti (DA) female rats compared to the controls and adjuvant-injected rats, using high-throughput technologies for gene expression and protein assays and focusing on the time-course between immunization, clinical onset (1, 5, 8 days post-immunization (DPI)), and progression (11 and 18 DPI). The expression profile of 84 genes related to T cell activation/signaling, adaptive immunity, cytokine/chemokine inflammation, demyelination, and cellular stress were analyzed in the tissue; 24 cytokines were measured in the CSF and plasma.

RESULTS

The macrophage colony-stimulating factor (CSF1) was the first up-regulated protein as far as 1 DPI, not only in blood but also in CSF and SC. A treatment with GW2580, a selective CSF1R inhibitor, slowed the disease progression, significantly reduced the severity, and prevented the relapse phase. Moreover, both pro-inflammatory (IL-1β, TNF-α) and anti-inflammatory cytokines (IL-5, IL-10, VEGF) were up-regulated starting from 8 DPI. Myelin genes were down-regulated starting from 8 DPI, especially MAL, MBP, and PMP22 while an opposite expression profile was observed for inflammation-related genes, such as CXCL11 and CXCL10.

CONCLUSIONS

This early cytokine and chemokine regulation indicates that novel biomarkers and therapeutic options could be explored in the asymptomatic phase of EAE. Overall, our findings provide clear evidence that CSF1R signaling regulates inflammation in EAE, supporting therapeutic targeting of CSF1R in MS.

Acute axonal damage in three different murine models of multiple sclerosis: A comparative approach

Axonal damage has been identified as a significant contributor to permanent clinical disability in multiple sclerosis. In the context of demyelinating disorders, this destructive event can be the result of inflammation, demyelination and/or the activation of innate defense cells such as microglia or monocytes. The relative contribution of each of these variables to acute axonal injury is, however, unknown. In the present study, we compared the extent of acute axonal damage in three different murine demyelination models using anti-amyloid precursor protein (APP) immunohistochemistry. T cell dependent (MOG_35-55-induced experimental autoimmune encephalomyelitis (EAE)) as well as T cell independent demyelination models (cuprizone- and lysolecithin-induced demyelination) were used. APP⁺ spheroids were present in all three experimental demyelination models. The number of APP⁺ spheroids was highest within LPC-induced lesions. Equal amounts were found in the spinal cord of MOG_35-55-EAE animals and the corpus callosum of cuprizone-intoxicated animals. Moreover, we detected increased immunoreactivity of the pre-synaptic protein vesicular glutamate transporter 1 (VGluT1) in demyelinated foci. VGluT1-staining revealed long stretched, ovoid-like axonal structures which co-localized with APP. In summary, we showed that acute axonal damage is evident under various experimental demyelination paradigms. Furthermore, disturbed axonal transport mechanisms, which are responsible for intra-axonal APP accumulation, do not only disturb APP, but also the transport of other synaptic proteins. These results indicate that, despite differences in their characteristics, all three models may serve as valid and suitable systems for investigating responsible mechanisms of axonal damage and potential protective strategies.

Diffusion tensor imaging of early relapsing-remitting multiple sclerosis with histogram analysis using automated segmentation and brain volume correction

Diffusion tensor magnetic resonance imaging (DTI) reveals measurable abnormalities in normal-appear ing brain tissue (NA BT) in established multiple sclerosis (MS). However, it is unclear how early this occurs. Recent studies have employed whole brain histogram analysis to improve sensitivity, but concern exists regarding reliability of tissue/cerebrospinal fluid segmentation and possible intersubject brain volume differences, which can introduce partial volume error. To address this, 28 early relapsing-remitting MS subjects [median disease duration 1.6 years; median Expanded Disability Status Scale (EDSS) score 1.5] and 20 controls were compared with whole brain histogram analysis using an automated segmentation algorithm to improve reproducibility. Brain parenchymal volumes (BPV) were estimated for each subject in the analysis. The mean, peak height and peak location were calculated for DTI parameters [fractional anisotropy (FA), mean diffusivity and volume ratio]. A n increased FA peak height in MS subject NA BT was observed (P =0.02) accounting for age, gender and BPV. Removing BPV revealed additional abnormalities in NABT. The main conclusions are i) FA peak height is increased in NA BT in early MS, ii) partial volume edge effects may contribute to apparent NA BT histogram abnormalities, and iii) correction for brain volume differences should reduce potential partial volume edge effects.

Important role of mast cells in multiple sclerosis

Autoimmunity is a disease that occurs when the body tissue is attacked by its own immune system. Multiple sclerosis (MS) is an autoimmune illness which triggers neurological progressive and persistent functions. MS is associated with an abnormal B-cell response and upregulation of T-cell reactivity against a multitude of antigens. Mast cells are the first line of the innate immune system and act by degranulating and secreting chemical mediators and cytokines. Their participation on the central nervous system has been recognized since the beginning of the last century. They have an important role in autoimmune disease, including MS where they mediate inflammation and demyelinization by presenting myelin antigens to T cells or disrupting the blood-brain barrier and permitting entry of inflammatory cells and cytokines. The participation of mast cells in MS is demonstrated by gene overexpression of chemical mediators and inflammatory cytokines. Here we report the relationship and involvement between mast cells and multiple sclerosis.

IL-21R signaling is critical for induction of spontaneous experimental autoimmune encephalomyelitis

IL-17-producing CD4+ T cells (Th17 cells) have well-described pathogenic roles in tissue inflammation and autoimmune diseases, such as experimental autoimmune encephalomyelitis (EAE); however, the involvement of IL-21 in these processes has remained controversial. While IL-21 is an essential autocrine amplification factor for differentiation of Th17 cells, the loss of IL-21 or IL-21 receptor (IL-21R) does not protect mice from actively induced EAE. Here, we utilized a transgenic EAE mouse model, in which T and B cells overexpress receptors for myelin oligodendrocyte glycoprotein (MOG) (referred to as 2D2xTH mice), and demonstrated that IL-21 is critical for the development of a variant form of spontaneous EAE in these animals. Il21r deletion in 2D2xTH mice reduced the incidence and severity of spontaneous EAE, which was associated with a defect in Th17 cell generation. Moreover, IL-21R deficiency limited IL-23R expression on Th17 cells and inhibited expression of key molecules involved in the generation of pathogenic Th17 cells. Conversely, loss of IL-23R in 2D2xTH mice resulted in complete resistance to the development of spontaneous EAE. Our data identify a previously unappreciated role for IL-21 in EAE and reveal that IL-21-mediated signaling supports generation and stabilization of pathogenic Th17 cells and development of spontaneous autoimmunity.

Alteration of synaptic connectivity of oligodendrocyte precursor cells following demyelination

Oligodendrocyte precursor cells (OPCs) are a major source of remyelinating oligodendrocytes in demyelinating diseases such as Multiple Sclerosis (MS). While OPCs are innervated by unmyelinated axons in the normal brain, the fate of such synaptic contacts after demyelination is still unclear. By combining electrophysiology and immunostainings in different transgenic mice expressing fluorescent reporters, we studied the synaptic innervation of OPCs in the model of lysolecithin (LPC)-induced demyelination of corpus callosum. Synaptic innervation of reactivated OPCs in the lesion was revealed by the presence of AMPA receptor-mediated synaptic currents, VGluT1+ axon-OPC contacts in 3D confocal reconstructions and synaptic junctions observed by electron microscopy. Moreover, 3D confocal reconstructions of VGluT1 and NG2 immunolabeling showed the existence of glutamatergic axon-OPC contacts in post-mortem MS lesions. Interestingly, patch-clamp recordings in LPC-induced lesions demonstrated a drastic decrease in spontaneous synaptic activity of OPCs early after demyelination that was not caused by an impaired conduction of compound action potentials. A reduction in synaptic connectivity was confirmed by the lack of VGluT1+ axon-OPC contacts in virtually all rapidly proliferating OPCs stained with EdU (50-ethynyl-20-deoxyuridine). At the end of the massive proliferation phase in lesions, the proportion of innervated OPCs rapidly recovers, although the frequency of spontaneous synaptic currents did not reach control levels. In conclusion, our results demonstrate that newly-generated OPCs do not receive synaptic inputs during their active proliferation after demyelination, but gain synapses during the remyelination process. Hence, glutamatergic synaptic inputs may contribute to inhibit OPC proliferation and might have a physiopathological relevance in demyelinating disorders.

CNS myelin sheath is stochastically built by homotypic fusion of myelin membranes within the bounds of an oligodendrocyte process

Myelin - the multilayer membrane that envelops axons - is a facilitator of rapid nerve conduction. Oligodendrocytes form CNS myelin; the prevailing hypothesis being that they do it by extending a process that circumnavigates the axon. It is pertinent to ask how myelin is built because oligodendrocyte plasma membrane and myelin are compositionally different. To this end, we examined oligodendrocyte cultures and embryonic avian optic nerves by electron microscopy, immuno-electron microscopy and three-dimensional electron tomography. The results support three novel concepts. Myelin membranes are synthesized as tubules and packaged into "myelinophore organelles" in the oligodendrocyte perikaryon. Myelin membranes are matured in and transported by myelinophore organelles within an oligodendrocyte process. The myelin sheath is generated by myelin membrane fusion inside an oligodendrocyte process. These findings abrogate the dogma of myelin resulting from a wrapping motion of an oligodendrocyte process and open up new avenues in the quest for understanding myelination in health and disease.

Validation survey of the impact of urinary incontinence (IIQ-7) and inventory of distress urogenital (UDI-6) - the short scales - in patients with multiple sclerosis

Cross-cultural adaptation and validation of the Impact Questionnaire of Urinary Incontinence (IIQ-7) and Urogenital Distress Inventory (UDI-6) - short scale - in the Brazilian population with multiple sclerosis. The IIQ-7 and UDI-6 were translated into Portuguese, called IIQ-7-BR and UDI-6-BR. The questionnaires were administered in 211 individuals selected randomly. Of these, 140 had MS according to McDonald criteria and 71 were included in the control group. In both questionnaires, the Cronbach's alpha coefficient was above 0.7. The IIQ-7-BR showed 94.31% concordance between the evaluated studies and UDI-6-BR, 93.33%. Thus, the instruments of this study were presented according to the standards proposed by the Instrument Review Criteria, reliability, validity and sensitivity, maintaining the original scales characteristics.

Glial metabotropic glutamate receptor-4 increases maturation and survival of oligodendrocytes

Group III metabotropic glutamate (mGlu) receptors mediate important neuroprotective and anti-inflammatory effects. Stimulation of mGlu4 receptor reduces neuroinflammation in a mouse model of experimental autoimmune encephalomyelitis (EAE) whereas mGlu4 knockout mice display exacerbated EAE clinical scores. We now show that mGlu4 receptors are expressed in oligodendrocytes, astrocytes and microglia in culture. Oligodendrocytes express mGlu4 receptors only at early stages of maturation (O4 positive), but not when more differentiated (myelin basic protein, MBP positive). Treatment of immature oligodendrocytes with the mGlu4 receptor agonist L-2-Amino-4-phosphonobutyrate (L-AP4; 50 μM for 48 h) accelerates differentiation with enhanced branching and earlier appearance of MBP staining. Oligodendrocyte death induced by exposure to 1 mM kainic acid for 24 h is significantly reduced by a 30-min pretreatment with L-AP4 (50 μM), an effect observed only in the presence of astrocytes, mimicked by the specific mGlu4 receptor positive allosteric modulator N-Phenyl-7-(hydroxyimino)cyclopropa[b]chromen-1a-carboxamide (PHCCC) (30 μM) and prevented by pretreatment with the mGlu4 receptor antagonist, cyclopropyl-4-phosphonophenylglycine (CPPG) (100 μM). In astrocytes, mGlu4 receptor is the most expressed among group III mGlu receptors, as by Quantitative real time PCR (QRT-PCR), and its silencing prevents protective effects. Protection is also observed when conditioned medium (CM) from L-AP4-pretreated astrocytes is transferred to oligodendrocytes challenged with kainic acid. Transforming growth factor β (TGF-β) mediates the increased oligodendrocyte survival as the effect of L-AP4 is mimicked by addition of 10 ng/ml TGF-β and prevented by incubation with a neutralizing anti-TGF-β antibody. In contrast, despite the expression of mGlu4 receptor in resting and activated microglia, CM from L-AP4-stimulated microglia does not modify kainate-induced oligodendrocyte toxicity. Our results suggest that mGlu4 receptors expressed in astrocytes mediate enhanced survival of oligodendrocytes under conditions of excitotoxicity.

Impact of mast cells on multiple sclerosis: inhibitory effect of natalizumab

Mast cells (MCs) derive from a distinct precursor in the bone marrow and are predominantly found in tissues at the interface between the host and the external environment where they can secrete mediators without overt degranulation. Mast cells mature under local tissue microenvironmental factors and are necessary for the development of allergic reactions, through crosslinking of their surface receptors for IgE (FcεRI), leading to degranulation and the release of vasoactive, pro-inflammatory and nociceptive mediators that include histamine, pro-inflammatory and anti-inflammatory cytokines and proteolytic enzymes. Multiple sclerosis (MS) is an autoimmune disease characterized by inflammatory demylination within the central nervous system. MCs are involved in the pathogenesis of MS by generating various vasoactive mediators and cytokines and participate in the destruction of the myelin sheath and the neuronal cells. The process of the development of demyelinating plaques in MS is probably linked with the rupture of the blood-brain barrier by MC products. The effects of natalizumab, which is a very effective drug in reducing the annualized relapse rate and other relapse-based endpoints, are discussed. Here, we report the relationship between MCs and MS.

Human recombinant domain antibodies against multiple sclerosis antigenic peptide CSF114(Glc)

Multiple sclerosis (MS) is a chronic auto-immune disease characterized by a damage to the myelin component of the central nervous system. Self-antigens created by aberrant glycosylation have been described to be a key component in the formation of auto-antibodies. CSF114(Glc) is a synthetic glucopeptide detecting in vitro MS-specific auto-antibodies, and it is actively used in diagnostics and research to monitor and quantify MS-associated Ig levels. We reasoned that antibodies raised against this probe could have been relevant for MS. We therefore screened a human Domain Antibody library against CSF114(Glc) using magnetic separation as a panning method. We obtained and described several clones, and the one with the highest signals was produced as a 6×His-tagged protein to properly study the binding properties as a soluble antibody. By surface plasmon resonance measurements, we evidenced that our clone recognized CSF114(Glc) with high affinity and specific for the glucosylated peptide. Kinetic parameters of peptide-clone interaction were calculated obtaining a value of KD in the nanomolar range. Harboring a human framework, this antibody should be very well tolerated by human immune system and may represent a valuable tool for MS diagnosis and therapy, paving the way to new research strategies.

Relapsing and progressive forms of multiple sclerosis: insights from pathology

PURPOSE OF REVIEW

The predominant clinical disease course of multiple sclerosis starts with reversible episodes of neurological disability, which transforms into progressive neurological decline. This review provides insight into the pathological differences during relapsing and progressive phases of multiple sclerosis.

RECENT FINDINGS

The clinical course of multiple sclerosis is variable, and the disease can be classified into relapsing and progressive phases. Pathological studies have been successful in distinguishing between these two forms of the disease and correlate with the clinical findings in terms of cellular responses, the inflammatory environment, and the location of lesions.

SUMMARY

Available therapies for multiple sclerosis patients, while effective during the relapsing phase, have little benefit for progressive multiple sclerosis patients. Development of therapies to benefit progressive multiple sclerosis patients will require a better understanding of the pathogenesis of progressive multiple sclerosis. This review discusses and compares the pathological findings in relapsing and progressive multiple sclerosis patients.

Relationship between damage to the cerebellar peduncles and clinical disability in multiple sclerosis

PURPOSE

To assess whether a structural disconnection between the cerebellum and the cerebral hemispheres contributes to cerebellar and brainstem symptoms in multiple sclerosis (MS).

MATERIALS AND METHODS

This study was approved by the local ethics committee, and written informed consent was obtained from each participant. Brain T2 lesion load, cerebellar white matter and gray matter volumes, and tract-specific measures of the middle and superior cerebellar peduncles were derived from 172 patients with MS and 46 control subjects. Predictors of clinical impairment, which was determined at ambulation and with cerebellar and brainstem functional system scores, were identified by using random forest analysis.

RESULTS

Of the 172 patients, 112 (65%) had middle cerebellar peduncle T2 lesions and 74 (43%) had superior cerebellar peduncle T2 lesions. T2 lesions in the middle and superior cerebellar peduncles were more common in clinically impaired patients than in unimpaired patients (P = .05 to <.0001). Most conventional magnetic resonance imaging metrics were more abnormal in impaired patients than in unimpaired patients (P = .03 to <.0001). Except for axial diffusivity, diffusivity abnormalities of the middle and superior cerebellar peduncles were more severe in clinically impaired patients than in unimpaired patients (P = .04 to <.0001). A minimal overlap was found between diffusivity abnormalities and T2 lesions. Compared with volumetric measures of T2 lesions or cerebellar atrophy, diffusivity measures of middle or superior cerebellar peduncle damage enabled better differentiation between clinically impaired and unimpaired patients (C statistics: 61%-70%).

CONCLUSION

The assessment of middle and superior cerebellar peduncle damage contributes to the explanation of cerebellar and/or brainstem symptoms and ambulatory impairment in MS.

Axonal loss in multiple sclerosis: causes and mechanisms

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system and the leading cause of non-traumatic neurologic disability in young adults in the United States and Europe. The disease course is variable and starts with reversible episodes of neurologic disability which transforms into continuous and irreversible neurologic decline. It is well established that loss of axons and neurons is the major cause of the progressive neurologic decline that most MS patients endure. Current hypotheses support primary inflammatory demyelination as the underlying cause of axonal loss during earlier stages in MS. The transition to progressive disease course is thought to occur when a threshold of neuronal and axonal loss is reached and the compensatory capacity of the central nervous system is surpassed. Available immunomodulatory therapies are of little benefit to MS after entering this irreversible phase of the disease. Elucidation of mechanisms that are responsible for axonal loss is therefore essential for the development of therapies directed to stop neurologic decline in MS patients. The current chapter reviews existing data on mechanisms of axonal pathology in MS.

Ascl1/Mash1 promotes brain oligodendrogenesis during myelination and remyelination

Oligodendrocytes are the myelin-forming cells of the CNS. They differentiate from oligodendrocyte precursor cells (OPCs) that are produced from progenitors throughout life but more actively during the neonatal period and in response to demyelinating insults. An accurate regulation of oligodendrogenesis is required to generate oligodendrocytes during these developmental or repair processes. We hypothesized that this regulation implicates transcription factors, which are expressed by OPCs and/or their progenitors. Ascl1/Mash1 is a proneural transcription factor previously implicated in embryonic oligodendrogenesis and operating in genetic interaction with Olig2, an essential transcriptional regulator in oligodendrocyte development. Herein, we have investigated the contribution of Ascl1 to oligodendrocyte development and remyelination in the postnatal cortex. During the neonatal period, Ascl1 expression was detected in progenitors of the cortical subventricular zone and in cortical OPCs. Different genetic approaches to delete Ascl1 in cortical progenitors or OPCs reduced neonatal oligodendrogenesis, showing that Ascl1 positively regulated both OPC specification from subventricular zone progenitors as well as the balance between OPC differentiation and proliferation. Examination of remyelination processes, both in the mouse model for focal demyelination of the corpus callosum and in multiple sclerosis lesions in humans, indicated that Ascl1 activity was upregulated along with increased oligodendrogenesis observed in remyelinating lesions. Additional genetic evidence indicated that remyelinating oligodendrocytes derived from Ascl1(+) progenitors/OPCs and that Ascl1 was required for proper remyelination. Together, our results show that Ascl1 function modulates multiple steps of OPC development in the postnatal brain and in response to demyelinating insults.

SOX17 is expressed in regenerating oligodendrocytes in experimental models of demyelination and in multiple sclerosis

We have previously demonstrated that Sox17 expression is prominent at developmental stages corresponding to oligodendrocyte progenitor cell (OPC) cycle exit and onset of differentiation, and that Sox17 promotes initiation of OPC differentiation. In this study, we examined Sox17 expression and regulation under pathological conditions, particularly in two animal models of demyelination/remyelination and in post-mortem multiple sclerosis (MS) brain lesions. We found that the number of Sox17 expressing cells was significantly increased in lysolecithin (LPC)-induced lesions of the mouse spinal cord between 7 and 30 days post-injection, as compared with controls. Sox17 immunoreactivity was predominantly detected in Olig2(+) and CC1(+) oligodendrocytes and rarely in NG2(+) OPCs. The highest density of Sox17(+) oligodendrocytes was observed at 2 weeks after LPC injection, coinciding with OPC differentiation. Consistent with these findings, in cuprizone-treated mice, Sox17 expression was highest in newly generated and in maturing CC1(+) oligodendrocytes, but low in NG2(+) OPCs during the demyelination and remyelination phases. In MS tissue, Sox17 was primarily detected in actively demyelinating lesions and periplaque white matter. Sox17 immunoreactivity was co-localized with NOGO-A+ post-mitotic oligodendrocytes both in active MS lesions and periplaque white matter. Taken together, our data: (i) demonstrate that Sox17 expression is highest in newly generated oligodendrocytes under pathological conditions and could be used as a marker of oligodendrocyte regeneration, and (ii) are suggestive of Sox17 playing a critical role in oligodendrocyte differentiation and lesion repair.

Brain pericyte plasticity as a potential drug target in CNS repair

Brain pericytes (BrPCs) are essential cellular components of the central nervous system neurovascular unit involved in the regulation of blood flow, blood-brain barrier function, as well as in the stabilization of the vessel architecture. More recently, it became evident that BrPCs, besides their regulatory activities in brain vessel function and homeostasis, have pleiotropic functions in the adult CNS ranging from stromal and regeneration promoting activities to stem cell properties. This special characteristic confers BrPC cell plasticity, being able to display features of other cells within the organism. BrPCs might also be causally involved in certain brain diseases. Due to these properties BrPCs might be potential drug targets for future therapies of neurological disorders. This review summarizes BrPC properties, disorders in which this cell type might be involved, and provides suggestions for future therapeutic developments targeting BrPCs.

Glycopeptide-based antibody detection in multiple sclerosis by surface plasmon resonance

In multiple sclerosis (MS) the gold standard for the diagnosis and prognosis is, up to now, the use of magnetic resonance imaging markers. No alternative simpler assays proven of use, except for cerebrospinal fluid analysis, have been provided in MS diagnosis. Therefore, there is a need to develop non-invasive, sensitive, simple new techniques for the clinical routine. Herein we present the evaluation of the feasibility of a glycopeptide-based biosensor to detect MS specific antibodies in sera using the surface plasmon resonance technology. The previously described glycopeptide antigen CSF114(Glc) has been immobilized on a gold sensor chip and the method has been optimized for real-time specific autoantibody detection directly in sera. A population of 60 healthy blood donors and 61 multiple sclerosis patients has been screened. The receiver operating characteristic (ROC)-based analysis has established the optimal diagnostic cut-off value for the method obtaining a sensitivity of 36% and a specificity of 95%. Sample sera have been also screened with a previously validated ELISA.

Two discreet subsets of CD8 T cells modulate PLP(91-110) induced experimental autoimmune encephalomyelitis in HLA-DR3 transgenic mice

Previously we showed that transgenic mice expressing human HLA-DR3 gene are susceptible to PLP(91-110) induced experimental autoimmune encephalomyelitis (EAE) and can serve as an animal model of multiple sclerosis (MS). HLA-DR3 mice with EAE showed increased number of CD8 T cells indicating their important role in disease pathogenesis. The role of CD8 T cells in MS, an inflammatory demyelinating disease of CNS, has been enigmatic as it has been assigned both regulatory and pathogenic roles. Therefore, to evaluate the role of CD8 T cells, we generated CD8 deficient HLA-DR3 transgenic mice (DR3.CD8(-/-)). Immunization with PLP(91-110) led to more severe EAE in DR3.CD8(-/-) mice compared to HLA-DR3 mice indicating a regulatory role for CD8 T cells. Interestingly, DR3.CD8(-/-) mice with EAE showed decreased CNS pathology compared to DR3 mice thus suggesting a pathogenic role for CD8 T cells. We show that these two subsets of CD8 T cells can be differentiated based on the surface expression of CD122 (IL-2 Rβ chain). CD8 T cells expressing CD122 (CD8+CD122+) play a regulatory role while CD8+CD122- T cells act as a pathogenic subset. CD122 expressing CD8 T cells are the regulatory subset of CD8 T cells and regulate the encephalitogenic CD4 T cells through direct modulation of antigen presenting cells and/or through the release of immunoregulatory cytokines such as IL-10, IFNγ and TGFβ. We also showed that adoptive transfer of CD8CD122- T cells caused increased spinal cord demyelination indicating that these are pathogenic subset of CD8 T cells. Our study suggests that CD8+ T cells play both regulatory as well as pathogenic role in disease pathogenesis of EAE. A better understanding of these subsets could aid in designing novel therapy for MS patients.

The remyelination Philosopher's Stone: stem and progenitor cell therapies for multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disease that leads to oligodendrocyte loss and subsequent demyelination of the adult central nervous system (CNS). The pathology is characterized by transient phases of recovery during which remyelination can occur as a result of resident oligodendroglial precursor and stem/progenitor cell activation. However, myelin repair efficiency remains low urging the development of new therapeutical approaches that promote remyelination activities. Current MS treatments target primarily the immune system in order to reduce the relapse rate and the formation of inflammatory lesions, whereas no therapies exist in order to regenerate damaged myelin sheaths. During the last few years, several transplantation studies have been conducted with adult neural stem/progenitor cells and glial precursor cells to evaluate their potential to generate mature oligodendrocytes that can remyelinate axons. In parallel, modulation of the endogenous progenitor niche by neural and mesenchymal stem cell transplantation with the aim of promoting CNS progenitor differentiation and myelination has been studied. Here, we summarize these findings and discuss the properties and consequences of the various molecular and cell-mediated remyelination approaches. Moreover, we address age-associated intrinsic cellular changes that might influence the regenerative outcome. We also evaluate the extent to which these experimental treatments might increase the regeneration capacity of the demyelinated human CNS and hence be turned into future therapies.

[Neuro-urological dysfunction of the lower urinary tract in CNS diseases: pathophysiology, epidemiology, and treatment options]

The lower urinary tract (LUT) is regulated by a complex neural network that is subject to supraspinal control. Neurological disorders, especially of the central nervous system (CNS), can rapidly lead to disruption of this control. Multiple sclerosis, Parkinson's disease, multiple system atrophy, and stroke are neurological disorders which quite frequently cause dysfunction of the LUT. With respect to the pathophysiology of bladder dysfunction in CNS diseases there are various hypotheses regarding the individual disorders: disturbances of neural communication between the frontal cortex and pontine micturition center, between the pontine micturition center and the lumbosacral parts of the spinal cord, and between the basal ganglia, thalamus, and anterior cingulate gyrus appear to play a pivotal role in the development of bladder dysfunction. The symptoms and urodynamic presentation of LUT dysfunction can vary considerably depending on the disease and disease progression and can change in the course of the disease. The incidence and prevalence of LUT dysfunctions rise with increasing progression of the underlying neurological disease.Various conservative, minimally invasive, and open surgical procedures are available to prevent harmful sequelae and to improve the quality of life of these patients. As yet, however, few data exist on most of the treatment options in cases of the above-mentioned CNS diseases. Intermittent self-catheterization and antimuscarinic medications are among the most important conservative treatment options. Injection of botulinum neurotoxin type A into the detrusor muscle and increasingly sacral or pudendal neuromodulation are among the most important minimally invasive treatment options. Surgical methods include reconstructive continent or incontinent urinary diversion.When planning therapy the patient's current needs and neurological limitations as well as possible disease progression must be taken into consideration. It is often advisable to consult with and enlist the cooperation of the attending neurologist when planning treatment.

Genetic background of multiple sclerosis

Multiple sclerosis (MS) is a one of the group of diseases labeled as "common complex". Virtually all common complex traits, genetic and environmental components have important roles, both independently and interactively, in disease susceptibility and stochastic and epigenetic effects cannot be overlooked. Data presented are largely part of the Canada-wide prospective, population-based longitudinal Canadian Collaborative Project on Genetic Susceptibility to MS (CCPGSMS) which includes over 30,000 unique families having at least 1 member with MS. Findings do not support a general propensity to autoimmune disease in MS families, but clearly highlight the importance of controlling for gender (patient, informant) when conducting such studies. The MHC class II association has been fine-mapped to the HLA-DRB5*0101-HLA-DRB1*1501-HLA-DQA1*0102-HLA-DQB1*0602 extended haplotype. This HLA haplotype confers a relative risk of approximately 3 and homozygosity for this haplotype increases the risk by over 6 fold. However, the HLA haplotype loci interactions are complex and include, epistasis, trans and cis effects, and parent-of-origin effects. As well, there may be interactions of EBV and vitamin D with the HLA, In conclusion, using MS as an example, susceptibility for common complex disease most likely results from interactions of genes, environmental interactions and gene/environment interactions.

An animal model of cortical and callosal pathology in multiple sclerosis

The pathological and radiological hallmarks of multiple sclerosis (MS) include multiple demyelinated lesions disseminated throughout the white matter of the central nervous system (CNS). More recently, the cerebral cortex has been shown to be affected in MS, but the elucidation of events causing cortical demyelination has been hampered by the lack of animal models reflecting such human cortical pathology. In this report, we have described the presence of cortical gray matter and callosal white matter demyelinating lesions in the chronic experimental autoimmune encephalomyelitis (EAE) mouse model of MS. Similar to the pathological lesions of MS patients, EAE lesions have been classified as type I-leukocortical, type II-intracortical and type III-subpial. All of these lesions had varying degrees of demyelination, inflammatory cells and reactive astrocytes. Similar to MS, cortical layers during EAE showed demyelination, microglia activation, synaptic protein alterations and apoptotic cells. In addition, the callosal white matter during EAE had many inflammatory demyelinating lesions and axon degeneration. Functional electrophysiological conduction analysis showed deficits in both myelinated and unmyelinated callosal axons during early and late EAE. The chronic EAE mouse model has features that mimic cortical and callosal pathology of MS, and can be potentially used to screen agents to prevent these features of disease.

Cleavage of transaldolase by granzyme B causes the loss of enzymatic activity with retention of antigenicity for multiple sclerosis patients

Multiple sclerosis (MS) is an autoimmune demyelinating disease of the CNS resulting from a progressive loss of oligodendrocytes. Transaldolase (TAL) is expressed at selectively high levels in oligodendrocytes of the brain, and postmortem sections show concurrent loss of myelin basic protein and TAL from sites of demyelination. Infiltrating CD8(+) CTLs are thought to play a key role in oligodendrocyte cell death. Cleavage by granzyme B (GrB) is predictive for autoantigenicity of self-proteins, thereby further implicating CTL-induced death in the initiation and propagation of autoimmunity. The precursor frequency and CTL activity of HLA-A2-restricted TAL 168-176-specific CD8(+) T cells is increased in MS patients. In this paper, we show that TAL, but not myelin basic protein, is specifically cleaved by human GrB. The recognition site of GrB that resulted in the cleavage of a dominant TAL fragment was mapped to a VVAD motif at aa residue 27 by N-terminal sequencing and confirmed by site-directed mutagenesis. The major C-terminal GrB cleavage product, residues 28-337, had no enzymatic activity but retained the antigenicity of full-length TAL, effectively stimulating the proliferation and CTL activity of PBMCs and of CD8(+) T cell lines from patients with MS. Sera of MS patients exhibited similar binding affinity to wild-type and GrB-cleaved TAL. Because GrB mediates the killing of target cells and cleavage by GrB is predictive of autoantigen status of self proteins, GrB-cleaved TAL-specific T cell-mediated cytotoxicity may contribute to the progressive destruction of oligodendrocytes in patients with MS.

Association between human herpesvirus 6 and occurrence of multiple sclerosis among Jordanian patients

OBJECTIVES

Multiple sclerosis (MS) is hypothesized to be caused by an infectious agent that initiates an autoimmune reaction. Among the infectious agents linked to MS is human herpesvirus 6 (HHV-6). Due to the high occurrence of MS among Jordanian population and the deficiency of MS studies in Jordan, the prevalence of HHV-6 in sera and cerebrospinal fluids (CSFs) of 36 MS patients was investigated.

MATERIALS AND METHODS

To increase the sensitivity of detection, nested polymerase chain reaction was utilized.

RESULTS

Although we were able to detect HHV-6 DNA in serum samples of 26% MS patients, no significant difference was found when compared to control individuals. In addition, lack of association between MS and presence of viral DNA in CSF samples was observed. Even within the analyzed MS patient population, an association of HHV-6 and MS in terms of gender, type of diagnosis, symptoms and disease score was not identified among Jordanian patients.

CONCLUSIONS

Although these results indicate lack of apparent association between HHV-6 to MS among Jordanian patients, heterogeneity related to genetic polymorphism as well as geographical distribution of the disease and of pathogens may be of significance.

Meningeal inflammation is not associated with cortical demyelination in chronic multiple sclerosis

Cortical demyelination can be extensive in chronic multiple sclerosis (MS) patients. Cortical lesions are not associated with lymphocyte infiltration, blood-brain barrier disruption, or complement deposition; therefore, their pathogenesis is unclear. We analyzed the extent and cellular composition of leptomeningeal inflammatory infiltrates and their relationship with cortical demyelinated lesions in brain autopsy samples from 28 chronic MS patients; samples from 6 nonneurological disease control patients were also studied. Immunohistochemistry was used to detect meningeal T cells, B cells, macrophages, mature and immature dendritic cells, T-helper cells, (activated) cytotoxic T cells, and plasma cells. Quantitative analysis revealed significant meningeal inflammation in chronic MS patients; T cells were the predominant inflammatory cells. Morphometric analysis was performed on coronal hemisphere sections of the MS cases to assess subpial demyelination; no correlation between the extent of subpial demyelination and extent of meningeal inflammation was identified. Moreover, no differences were observed in the degree or cellular composition of meningeal infiltrates in areas directly adjacent to subpial lesions compared with areas adjacent to normal-appearing gray matter in the MS cases. In addition, no follicle-like structures were found in the MS samples. Our data suggest that the occurrence of cortical lesions is not related to the presence of meningeal inflammation in a large number of chronic MS patients.

Monitoring of acute axonal injury in the swine spinal cord with EAE by diffusion tensor imaging

PURPOSE

To evaluate the ability of diffusion tensor imaging (DTI) to detect and monitor acute axonal injury in swine spinal cord with acute experimental allergic encephalomyelitis (EAE).

MATERIALS AND METHODS

Magnetic resonance imaging of the cervical spinal cord was performed in vivo at different time points through the onset and progression of EAE using a 3 Tesla clinical scanner. The DTI parameters were calculated in four separate regions of interest at the C2/C3 level. The quantitative DTI-pathology and DTI-clinical correlations were verified.

RESULTS

In the monophasic acute course of EAE onset and progression, axial diffusivity (AD) decrease correlates with acute axonal injury (r = -0.84; P < 0.001). By contrast, radial diffusivity does not change and no demyelination in histopathology was detected. Moreover, a clear correlation between clinical disease and axial diffusivity was found in two swine EAE models (r = -0.86; P < 0.001 and r = -0.92; P < 0.001).

CONCLUSION

AD corresponds with axonal injury in the absence of demyelination and may be a useful noninvasive tool to investigate the underlying pathogenic processes of multiple sclerosis and to monitor the effects of experimental treatments for axonal injury.

Immune system markers of neuroinflammation in patients with clinical diagnose of neuromyelitis optica

Neuromyelitis optica (NMO) is an inflammatory, demyelinating disease of the central nervous system characterized by the association of a serious myelitis and unilateral or bilateral optic neuritis. The present study aimed to analyze the immunological parameters of NMO patients with diagnosis established based on Wingerchuck et al. (1999) criteria. Production of IgG and IgA antibodies to antigens of MBP, PLP 95-116, MOG 92-106, and the cytokines interleukin-4 (IL-4) and interferon-gamma (INF-gamma) were assessed by Elisa assay. The cohort was formed by 28 NMO patients and a matched healthy control group. NMO patients had significant high levels of IgG to MOG (p<0.0001), PLP (p=0.0002) and MBP (p<0.0001), and solely IgA to MBP (p<0.0001). INF-gamma (p=0.61) levels were similar to healthy controls. Increased production of IL-4 (p=0.0084) indicates an important role for this cytokine in the activation of Th2 regulatory cells and of the IgA producers B lymphocyte indicating activation of humoral immunity.

Review: Mitochondria and disease progression in multiple sclerosis

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system. Recent evidence suggests that dysfunction of surviving demyelinated axons and axonal degeneration contribute to the progression of MS. We review the evidence for and potential mechanisms of degeneration as well as dysfunction of chronically demyelinated axons in MS with particular reference to mitochondria, the main source of adenosine-5'-triphosphate in axons. Besides adenosine-5'-triphosphate production, mitochondria play an important role in calcium handling and produce reactive oxygen species. The mitochondrial changes in axons lacking healthy myelin sheaths as well as redistribution of sodium channels suggest that demyelinated axons would be more vulnerable to energy deficit than myelinated axons. A dysfunction of mitochondria in lesions as well as in the normal-appearing white and grey matter is increasingly recognized in MS and could be an important determinant of axonal dysfunction and degeneration. Mitochondria are a potential therapeutic target in MS.

Abundant extracellular myelin in the meninges of patients with multiple sclerosis

BACKGROUND

In multiple sclerosis (MS) myelin debris has been observed within MS lesions, in cerebrospinal fluid and cervical lymph nodes, but the route of myelin transport out of the brain is unknown. Drainage of interstitial fluid from the brain parenchyma involves the perivascular spaces and leptomeninges, but the presence of myelin debris in these compartments has not been described.

AIMS

To determine whether myelin products are present in the meninges and perivascular spaces of MS patients.

METHODS

Formalin-fixed brain tissue containing meninges from 29 MS patients, 9 non-neurological controls, 6 Alzheimer's disease, 5 stroke, 5 meningitis and 7 leucodystrophy patients was investigated, and immunohistochemically stained for several myelin proteins [proteolipid protein (PLP), myelin basic protein (MBP), myelin oligodendrocyte glycoprotein (MOG) and 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase)]. On brain material from MS patients and (non)neurological controls, PLP immunostaining was used to systematically investigate the presence of myelin debris in the meninges, using a semiquantitative scale.

RESULTS

Extensive extracellular presence of myelin particles, positive for PLP, MBP, MOG and CNPase in the leptomeninges of MS patients, was observed. Myelin particles were also observed in perivascular spaces of MS patients. Immunohistochemical double-labelling for macrophage and dendritic cell markers and PLP confirmed that the vast majority of myelin particles were located extracellularly. Extracellular myelin particles were virtually absent in meningeal tissue of non-neurological controls, Alzheimer's disease, stroke, meningitis and leucodystrophy cases.

CONCLUSIONS

In MS leptomeninges and perivascular spaces, abundant extracellular myelin can be found, whereas this is not the case for controls and other neurological disease. This may be relevant for understanding sustained immunogenicity or, alternatively, tolerogenicity in MS.

The genetics of clinical outcome in multiple sclerosis

Multiple sclerosis (MS) is a common inflammatory disease of the central nervous system (CNS), the clinical course of which varies considerably between patients. Genetic complexity and interactions with as yet unknown environmental factors have hindered researchers from fully elucidating the aetiology of the disease. In addition to influencing disease susceptibility, epidemiological evidence suggests that genetic factors may affect phenotypic expression of the disease. Genes that affect clinical outcome may be more effective therapeutic targets than those which determine susceptibility. We present in this review a comprehensive survey of the genes (both MHC- and non-MHC-related) that have been investigated for their role in disease outcome in MS. Recent studies implicating the role of the genotype and epistatic interactions in the MHC in determining outcome are highlighted.

Variants of ST8SIA1 are associated with risk of developing multiple sclerosis

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system of unknown etiology with both genetic and environmental factors playing a role in susceptibility. To date, the HLA DR15/DQ6 haplotype within the major histocompatibility complex on chromosome 6p, is the strongest genetic risk factor associated with MS susceptibility. Additional alleles of IL7 and IL2 have been identified as risk factors for MS with small effect. Here we present two independent studies supporting an allelic association of MS with polymorphisms in the ST8SIA1 gene, located on chromosome 12p12 and encoding ST8 alpha-N-acetyl-neuraminide alpha-2,8-sialyltransferase 1. The initial association was made in a single three-generation family where a single-nucleotide polymorphism (SNP) rs4762896, was segregating together with HLA DR15/DQ6 in MS patients. A study of 274 family trios (affected child and both unaffected parents) from Australia validated the association of ST8SIA1 in individuals with MS, showing transmission disequilibrium of the paternal alleles for three additional SNPs, namely rs704219, rs2041906, and rs1558793, with p = 0.001, p = 0.01 and p = 0.01 respectively. These findings implicate ST8SIA1 as a possible novel susceptibility gene for MS.