Immunological patterns identifying disease course and evolution in multiple sclerosis patients

CCR6 Expression on B Cells Is Not Required for Clinical or Pathological Presentation of MOG Protein-Induced Experimental Autoimmune Encephalomyelitis despite an Altered Germinal Center Response

B cells have been implicated in the pathogenesis of multiple sclerosis, but the mechanisms that guide B cell activation in the periphery and subsequent migration to the CNS remain incompletely understood. We previously showed that systemic inflammation induces an accumulation of B cells in the spleen in a CCR6/CCL20-dependent manner. In this study, we evaluated the role of CCR6/CCL20 in the context of myelin oligodendrocyte glycoprotein (MOG) protein-induced (B cell-dependent) experimental autoimmune encephalomyelitis (EAE). We found that CCR6 is upregulated on murine B cells that migrate into the CNS during neuroinflammation. In addition, human B cells that migrate across CNS endothelium in vitro were found to be CCR6⁺, and we detected CCL20 production by activated CNS-derived human endothelial cells as well as a systemic increase in CCL20 protein during EAE. Although mice that lack CCR6 expression specifically on B cells exhibited an altered germinal center reaction in response to MOG protein immunization, CCR6-deficient B cells did not exhibit any competitive disadvantage in their migration to the CNS during EAE, and the clinical and pathological presentation of EAE induced by MOG protein was unaffected. These data, to our knowledge, provide new information on the role of B cell-intrinsic CCR6 expression in a B cell-dependent model of neuroinflammation.

Serum CCL20 and its association with SIRT1 activity in multiple sclerosis patients

CCL20 is a potentially important component in the pathogenesis of multiple sclerosis (MS). SIRT1 exhibits a negative regulatory effect on a variety of inflammatory cytokines and can relieve experimental autoimmune encephalomyelitis. The association between the level of CCL20 and SIRT1 activity in MS patients has not been investigated. In the present study, blood samples were collected from 38 RRMS patients and 40 healthy controls. The serum CCL20 levels were measured by ELISA. SIRT1 activity was evaluated by fluorometric assay. We revealed elevated serum CCL20 concentrations in MS, and discovered an inverse correlation between CCL20 and SIRT1 activity in MS patients.

CCL5-Glutamate Cross-Talk in Astrocyte-Neuron Communication in Multiple Sclerosis

The immune system (IS) and the central nervous system (CNS) are functionally coupled, and a large number of endogenous molecules (i.e., the chemokines for the IS and the classic neurotransmitters for the CNS) are shared in common between the two systems. These interactions are key elements for the elucidation of the pathogenesis of central inflammatory diseases. In recent years, evidence has been provided supporting the role of chemokines as modulators of central neurotransmission. It is the case of the chemokines CCL2 and CXCL12 that control pre- and/or post-synaptically the chemical transmission. This article aims to review the functional cross-talk linking another endogenous pro-inflammatory factor released by glial cells, i.e., the chemokine Regulated upon Activation Normal T-cell Expressed and Secreted (CCL5) and the principal neurotransmitter in CNS (i.e., glutamate) in physiological and pathological conditions. In particular, the review discusses preclinical data concerning the role of CCL5 as a modulator of central glutamatergic transmission in healthy and demyelinating disorders. The CCL5-mediated control of glutamate release at chemical synapses could be relevant either to the onset of psychiatric symptoms that often accompany the development of multiple sclerosis (MS), but also it might indirectly give a rationale for the progression of inflammation and demyelination. The impact of disease-modifying therapies for the cure of MS on the endogenous availability of CCL5 in CNS will be also summarized. We apologize in advance for omission in our coverage of the existing literature.

Prophylactic versus Therapeutic Fingolimod: Restoration of Presynaptic Defects in Mice Suffering from Experimental Autoimmune Encephalomyelitis

Fingolimod, the first oral, disease-modifying therapy for MS, has been recently proposed to modulate glutamate transmission in the central nervous system (CNS) of mice suffering from Experimental Autoimmune Encephalomyelitis (EAE) and in MS patients. Our study aims at investigating whether oral fingolimod recovers presynaptic defects that occur at different stages of disease in the CNS of EAE mice. In vivo prophylactic (0.3 mg/kg for 14 days, from the 7th day post immunization, d.p.i, the drug dissolved in the drinking water) fingolimod significantly reduced the clinical symptoms and the anxiety-related behaviour in EAE mice. Spinal cord inflammation, demyelination and glial cell activation are markers of EAE progression. These signs were ameliorated following oral fingolimod administration. Glutamate exocytosis was shown to be impaired in cortical and spinal cord terminals isolated from EAE mice at 21 ± 1 d.p.i., while GABA alteration emerged only at the spinal cord level. Prophylactic fingolimod recovered these presynaptic defects, restoring altered glutamate and GABA release efficiency. The beneficial effect occurred in a dose-dependent, region-specific manner, since lower (0.1-0.03 mg/kg) doses restored, although to a different extent, synaptic defects in cortical but not spinal cord terminals. A delayed reduction of glutamate, but not of GABA, exocytosis was observed in hippocampal terminals of EAE mice at 35 d.p.i. Therapeutic (0.3 mg/kg, from 21 d.p.i. for 14 days) fingolimod restored glutamate exocytosis in the cortex and in the hippocampus of EAE mice at 35 ± 1 d.p.i. but not in the spinal cord, where also GABAergic defects remained unmodified. These results improve our knowledge of the molecular events accounting for the beneficial effects elicited by fingolimod in demyelinating disorders.

Siponimod (BAF312) prevents synaptic neurodegeneration in experimental multiple sclerosis

Background

Data from multiple sclerosis (MS) and the MS rodent model, experimental autoimmune encephalomyelitis (EAE), highlighted an inflammation-dependent synaptopathy at the basis of the neurodegenerative damage causing irreversible disability in these disorders. This synaptopathy is characterized by an imbalance between glutamatergic and GABAergic transmission and has been proposed to be a potential therapeutic target.

Siponimod (BAF312), a selective sphingosine 1-phosphate1,5 receptor modulator, is currently under investigation in a clinical trial in secondary progressive MS patients. We investigated whether siponimod, in addition to its peripheral immune modulation, may exert direct neuroprotective effects in the central nervous system (CNS) of mice with chronic progressive EAE.

Methods

Minipumps allowing continuous intracerebroventricular (icv) infusion of siponimod for 4 weeks were implanted into C57BL/6 mice subjected to MOG_35-55-induced EAE. Electrophysiology, immunohistochemistry, western blot, qPCR experiments, and peripheral lymphocyte counts were performed. In addition, the effect of siponimod on activated microglia was assessed in vitro to confirm the direct effect of the drug on CNS-resident immune cells.

Results

Siponimod administration (0.45 μg/day) induced a significant beneficial effect on EAE clinical scores with minimal effect on peripheral lymphocyte counts. Siponimod rescued defective GABAergic transmission in the striatum of EAE, without correcting the EAE-induced alterations of glutamatergic transmission. We observed a significant attenuation of astrogliosis and microgliosis together with reduced lymphocyte infiltration in the striatum of EAE mice treated with siponimod. Interestingly, siponimod reduced the release of IL-6 and RANTES from activated microglial cells in vitro, which might explain the reduced lymphocyte infiltration. Furthermore, the loss of parvalbumin-positive (PV+) GABAergic interneurons typical of EAE brains was rescued by siponimod treatment, providing a plausible explanation of the selective effects of this drug on inhibitory synaptic transmission.

Conclusions

Altogether, our results show that siponimod has neuroprotective effects in the CNS of EAE mice, which are likely independent of its peripheral immune effect, suggesting that this drug could be effective in limiting neurodegenerative pathological processes in MS.

Identification of a novel mechanism of action of fingolimod (FTY720) on human effector T cell function through TCF-1 upregulation

Background

Fingolimod (FTY720), the first oral treatment for multiple sclerosis (MS), blocks immune cell trafficking and prevents disease relapses by downregulation of sphingosine-1-phosphate receptor. We determined the effect of FTY720 on human T cell activation and effector function.

Methods

T cells from MS patients and healthy controls were isolated to measure gene expression profiles in the presence or absence of FTY720 using nanostring and quantitative real-time polymerase chain reaction (qPCR). Cytokine protein expression was measured using luminex assay and flow cytometry analysis. Lentivirus vector carrying short hairpin RNA (shRNA) was used to knock down the expression of specific genes in CD4+ T cells. Chromatin immunoprecipitation was performed to assess T cell factor 1 (TCF-1) binding to promoter regions. Luciferase assays were performed to test the direct regulation of interferon gamma (IFN-γ) and granzyme B (GZMB) by TCF-1. Western blot analysis was used to assess the phosphorylation status of Akt and GSK3β.

Results

We showed that FTY720 treatment not only affects T cell trafficking but also T cell activation. Patients treated with FTY720 showed a significant reduction in circulating CD4 T cells. Activation of T cells in presence of FTY720 showed a less inflammatory phenotype with reduced production of IFN-γ and GZMB. This decreased effector phenotype of FTY720-treated T cells was dependent on the upregulation of TCF-1. FTY720-induced TCF-1 downregulated the pathogenic cytokines IFN-γ and GZMB by binding to their promoter/enhancer regions and mediating epigenetic modifications. Furthermore, we observed that TCF-1 expression was lower in T cells from multiple sclerosis patients than in those from healthy individuals, and FTY720 treatment increased TCF-1 expression in multiple sclerosis patients.

Conclusions

These results reveal a previously unknown mechanism of the effect of FTY720 on human CD4+ T cell modulation in multiple sclerosis and demonstrate the role of TCF-1 in human T cell activation and effector function.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-015-0460-z) contains supplementary material, which is available to authorized users.

Dimethyl Fumarate Protects Neural Stem/Progenitor Cells and Neurons from Oxidative Damage through Nrf2-ERK1/2 MAPK Pathway

Multiple sclerosis (MS) is the most common multifocal inflammatory demyelinating disease of the central nervous system (CNS). Due to the progressive neurodegenerative nature of MS, developing treatments that exhibit direct neuroprotective effects are needed. Tecfidera™ (BG-12) is an oral formulation of the fumaric acid esters (FAE), containing the active metabolite dimethyl fumarate (DMF). Although BG-12 showed remarkable efficacy in lowering relapse rates in clinical trials, its mechanism of action in MS is not yet well understood. In this study, we reported the potential neuroprotective effects of dimethyl fumarate (DMF) on mouse and rat neural stem/progenitor cells (NPCs) and neurons. We found that DMF increased the frequency of the multipotent neurospheres and the survival of NPCs following oxidative stress with hydrogen peroxide (H₂O₂) treatment. In addition, utilizing the reactive oxygen species (ROS) assay, we showed that DMF reduced ROS production induced by H₂O₂. DMF also decreased oxidative stress-induced apoptosis. Using motor neuron survival assay, DMF significantly promoted survival of motor neurons under oxidative stress. We further analyzed the expression of oxidative stress-induced genes in the NPC cultures and showed that DMF increased the expression of transcription factor nuclear factor-erythroid 2-related factor 2 (Nrf2) at both levels of RNA and protein. Furthermore, we demonstrated the involvement of Nrf2-ERK1/2 MAPK pathway in DMF-mediated neuroprotection. Finally, we utilized SuperArray gene screen technology to identify additional anti-oxidative stress genes (Gstp1, Sod2, Nqo1, Srxn1, Fth1). Our data suggests that analysis of anti-oxidative stress mechanisms may yield further insights into new targets for treatment of multiple sclerosis (MS).

Comparison of Antioxidant Status and Vitamin D Levels between Multiple Sclerosis Patients and Healthy Matched Subjects

Objective. The aim of the present study was to compare the serum levels of total antioxidant status (TAS) and 25(OH) D3 and dietary intake of multiple sclerosis (MS) patients with those of normal subjects. Method. Thirty-seven MS patients (31 women) and the same number of healthy matched controls were compared for their serum levels and dietary intake of 25(OH) D3 and TAS. Sun exposure and the intake of antioxidants and vitamin D rich foods were estimated through face-to-face interview and food frequency questionnaire. Results. Dietary intake of antioxidants and vitamin D rich foods, vitamin C, vitamin A, and folate was not significantly different between the two groups. There were also no significant differences in the mean levels of 25(OH) D3 and TAS between the study groups. Both groups had low serum levels of 25(OH) D3 and total antioxidants. Conclusion. No significant differences were detected in serum levels and dietary intake of vitamin D and antioxidants between MS patients and healthy controls. All subjects had low antioxidant status and vitamin D levels.

CCL5-glutamate interaction in central nervous system: Early and acute presynaptic defects in EAE mice

We investigated the CCL5-glutamate interaction in the cortex and in the spinal cord from mice with Experimental Autoimmune Encephalomyelitis (EAE) at 13 and 21/30 days post immunization (d.p.i.), representing the onset and the peak of the disease, respectively. An early reduction of the KCl-evoked glutamate release was observed in cortical terminals from EAE mice at 13 d.p.i., persisting until 21/30 d.p.i. A concomitant reduction of the depolarization-evoked cyclic adenosine monophosphate (cAMP), but not of the inositol 1,4,5-trisphosphate (IP3) cortical production also occurred at 13 d.p.i, that still was detectable at the acute stage of disease (21 dp.i.). Inasmuch, the CCL5-mediated inhibition of glutamate exocytosis observed in control mice turned to facilitation in EAE mouse cortex at 13 d.p.i., then becoming undetectable at 21/30 d.p.i. Differently, glutamate exocytosis, as well as IP3 and cAMP productions were unaltered in spinal cord synaptosomes from EAE mice at 13 d.p.i., but significantly increased at 21/30 d.p.i., while the presynaptic CCL5-mediated facilitation of glutamate exocytosis observed in control mice remained unchanged. In both CNS regions, the presynaptic defects were parallelled by increased CCL5 availability. Inasmuch, the presynaptic defects so far described in EAE mice were reminiscent of the effects acute CCL5 exerts in control conditions. Based on these observations we propose that increased CCL5 bioavailability could have a role in determining the abovedescribed impaired presynaptic impairments in both CNS regions. These presynaptic defects could be relevant to the onset of early cognitive impairments and acute neuroinflammation and demyelinating processes observed in multiple sclerosis patients.

A novel data mining system points out hidden relationships between immunological markers in multiple sclerosis

BACKGROUND

Multiple Sclerosis (MS) is a multi-factorial disease, where a single biomarker unlikely can provide comprehensive information. Moreover, due to the non-linearity of biomarkers, traditional statistic is both unsuitable and underpowered to dissect their relationship. Patients affected with primary (PP=14), secondary (SP=33), benign (BB=26), relapsing-remitting (RR=30) MS, and 42 sex and age matched healthy controls were studied. We performed a depth immune-phenotypic and functional analysis of peripheral blood mononuclear cell (PBMCs) by flow-cytometry. Semantic connectivity maps (AutoCM) were applied to find the natural associations among immunological markers. AutoCM is a special kind of Artificial Neural Network able to find consistent trends and associations among variables. The matrix of connections, visualized through minimum spanning tree, keeps non linear associations among variables and captures connection schemes among clusters.

RESULTS

Complex immunological relationships were shown to be related to different disease courses. Low CD4IL25+ cells level was strongly related (link strength, ls=0.81) to SP MS. This phenotype was also associated to high CD4ROR+ cells levels (ls=0.56). BB MS was related to high CD4+IL13 cell levels (ls=0.90), as well as to high CD14+IL6 cells percentage (ls=0.80). RR MS was strongly (ls=0.87) related to CD4+IL25 high cell levels, as well indirectly to high percentages of CD4+IL13 cells. In this latter strong (ls=0.92) association could be confirmed the induction activity of the former cells (CD4+IL25) on the latter (CD4+IL13). Another interesting topographic data was the isolation of Th9 cells (CD4IL9) from the main part of the immunological network related to MS, suggesting a possible secondary role of this new described cell phenotype in MS disease.

CONCLUSIONS

This novel application of non-linear mathematical techniques suggests peculiar immunological signatures for different MS phenotypes. Notably, the immune-network displayed by this new method, rather than a single marker, might be viewed as the right target of immunotherapy. Furthermore, this new statistical technique could be also employed to increase the knowledge of other age-related multifactorial disease in which complex immunological networks play a substantial role.

Evaluation of serum oxidant/antioxidant balance in multiple sclerosis

The total oxidative status (TOS)/total anti-oxidative status (TAS) ratio can provide information on an individual's absolute oxidative stress index (OSI). We investigated the alterations in the oxidant-antioxidant balance by measuring the oxidant parameters OSI, TOS, and malondialdehyde (MDA) together with the antioxidant parameters such as TAS, and superoxide dismutase (SOD) in patients with relapsing remitting multiple sclerosis (MS). To our knowledge, this is the first study to evaluate OSI in patients with relapsing remitting MS. 35 ambulatory patients with relapsing-remitting MS (35.8 ± 8.7 years) and 32 age- and activity-matched healthy control subjects (35.1 ± 3.7 years) that participated in the study. Serum TAS and TOS levels were determined using new automated methods. MS patients had higher concentrations of MDA (151.5 ± 51.1 vs. 111.3 ± 27.4 nmol/g protein, respectively; p < 0.001), TOS (148.1 ± 162.5 vs. 48.3 ± 46.4 mmol H(2)O(2) Equiv./g protein, respectively; p = 0.002), OSI (21124 ± 32543 vs. 5294 ± 5562, respectively; p = 0.008), and SOD (4.5 ± 0.7 vs. 3.4 ± 0.6 U/L, respectively; p < 0.001) compared with healthy controls. On the other hand, MS patients had lower concentrations of NO (12.3 ± 6.9 vs. 17.4 ± 2.5 μmol/g protein, respectively; p < 0.001) and TAS (0.82 ± 0.27 vs. 0.26 ± 0.15, respectively; p = 0.011) compared with healthy controls. In conclusion, these findings indicate that the oxidative stress plays an important role in the pathogenesis of MS.

MicroRNA and mRNA expression profile screening in multiple sclerosis patients to unravel novel pathogenic steps and identify potential biomarkers

Identification of novel targets and biomarkers, such as microRNAs, is extremely helpful to understand the pathogenetic mechanisms in a disease like multiple sclerosis (MS). We tested the expression profile of 1145 microRNAs in peripheral blood mononuclear cells (PBMCs) of 19 MS patients and 14 controls, and we further explored their function by performing a whole-genome mRNA profiling in same subjects and using bioinformatic prediction tool. A total of 104 miRNAs have been identified as deregulated in MS patients; 2/10 which ranked highest (let-7g and miR-150) have been validated in a replication sample, leading to the identification of putative target genes.

Evaluation of serum levels of chemokines during interferon-β treatment in multiple sclerosis patients: a 1-year, observational cohort study

BACKGROUND

The molecules that provide access to activated T cells in the CNS, including chemokines, have been considered to be a crucial step in the pathogenesis of multiple sclerosis (MS).

AIMS

In this study, we investigated serial serum chemokine levels in patients with relapsing-remitting MS over 1 year and the association of these chemokine levels with treatment regimens, lesions on MRI and patients' characteristics.

METHODS

Serum CXCL9, CXCL10, CCL2, CCL4 and CCL5 levels were evaluated using ELISA every 2 months for a year in 28 healthy controls and 28 MS patients during their treatment with interferon (IFN)-β. Patients underwent MRI and were evaluated using the Expanded Disability Status Scale (EDSS) at the first and final evaluations.

RESULTS

CXCL10 serum levels were higher in MS patients compared with controls, were positively correlated with T2 lesions on MRI and were slightly increased during relapses. Treatment with IFNβ-1a or IFNβ-1b was associated with increased CXCL10 levels when evaluated more than 36 hours after subcutaneous injection. The CXCL9 levels were higher after MS relapse. There was significant variability in CCL4 and CCL5 levels in the serial evaluations, associated with gender and treatment. CCL2 levels were higher in treated MS patients than healthy controls, particularly among those patients with a stable form of the disease.

CONCLUSION

Serum is a feasible resource for searching for an immunological marker in MS. Peripheral chemokine levels correlated in different ways with IFNβ therapy and with disease and patient characteristics.

CLINICAL TRIAL REGISTRATION NUMBER

ISRCTN45526724.

An immune paradox: how can the same chemokine axis regulate both immune tolerance and activation?: CCR6/CCL20: a chemokine axis balancing immunological tolerance and inflammation in autoimmune disease

Chemokines (chemotactic cytokines) drive and direct leukocyte traffic. New evidence suggests that the unusual CCR6/CCL20 chemokine receptor/ligand axis provides key homing signals for recently identified cells of the adaptive immune system, recruiting both pro-inflammatory and suppressive T cell subsets. Thus CCR6 and CCL20 have been recently implicated in various human pathologies, particularly in autoimmune disease. These studies have revealed that targeting CCR6/CCL20 can enhance or inhibit autoimmune disease depending on the cellular basis of pathogenesis and the cell subtype most affected through different CCR6/CCL20 manipulations. Here, we discuss the significance of this chemokine receptor/ligand axis in immune and inflammatory functions, consider the potential for targeting CCR6/CCL20 in human autoimmunity and propose that the shared evolutionary origins of pro-inflammatory and regulatory T cells may contribute to the reason why both immune activation and regulation might be controlled through the same chemokine pathway.

Clinical study on CXCL13, CCL17, CCL20 and IL-17 as immune cell migration navigators in relapsing-remitting multiple sclerosis patients

BACKGROUND

There has been a growing evidence for the role of chemokines in the pathology of multiple sclerosis. Recently, there has been great emphasis placed on humoral immunity and the T(H)-17 response, which has not yet been thoroughly described in MS. The aim of this study was to investigate the role of specific chemokines involved in B-cell migration (CXCL13) and in the T(H)-17 immune response (IL-17, CCL17, CCL20).

METHODS

Using ELISA, the chosen chemokine concentrations were measured in the serum and cerebrospinal fluid of relapsing-remitting MS patients with both active and stable disease, and the relapse prediction rate was calculated.

RESULTS

We found that the CSF concentrations of CXCL13 in patients with RRMS both, during relapse and remission, were significantly higher than in controls. CCL17 and CCL20 were not detected in CSF in either of the groups, whereas serum CCL20 level was significantly higher in remission than during relapse. Intravenous methylprednisolone treatment of patients with relapse did not influence serum CXCL13 and CCL20 levels. However, it did lower CCL17 and IL-17 concentrations.

CONCLUSIONS

CXCL13 is an important mediator in MS that is strongly linked to the neuroinflammatory activity of the disease. However, more studies are needed for elucidating the roles of CCL17, CCL20 and IL-17 in MS pathology.

Altered M1/M2 activation patterns of monocytes in severe relapsing experimental rat model of multiple sclerosis. Amelioration of clinical status by M2 activated monocyte administration

OBJECTIVES

We investigated proinflammatory M1 and immunomodulatory M2 activation profiles of circulating monocytes in relapsing experimental autoimmune encephalomyelitis (EAE) model of multiple sclerosis, and tested whether altered M1/M2 equilibrium promotes CNS inflammation.

RESULTS

Approaches of MRI macrophage tracking with USPIO nanoparticles and expression patterns of M1/M2 macrophages and microglia in brain and M1/M2 monocytes in blood samples at various disease stages revealed that M1/M2 equilibrium in blood and CNS favors mild EAE, while imbalance towards M1 promotes relapsing EAE. We consequently investigated whether M2 activated monocyte restoration in peripheral blood could cure acute clinical EAE disease. Administration of ex vivo activated M2 monocytes both suppressed ongoing severe EAE and increased immunomodulatory expression pattern in lesions, confirming their role in the induction of recovery.

CONCLUSION

We conclude that imbalance of monocyte activation profiles and impaired M2 expression, are key factors in development of relapses. Our study opens new perspectives for therapeutic applications in MS.

Elevated ATG5 expression in autoimmune demyelination and multiple sclerosis

Multiple sclerosis (MS) is an inflammatory central nervous system (CNS) disorder characterized by T cell-mediated demyelination. In MS, prolonged T cell survival and increased T cell proliferation have been linked to disease relapse and progression. Recently, the autophagy-related gene 5 (Atg5) has been shown to modulate T cell survival. In this study, we examined the expression of Atg5 using both a mouse model of autoimmune demyelination as well as blood and brain tissues from MS cases. Quantitative real-time PCR analysis of RNA isolated from blood samples of experimental autoimmune encephalomyelitis (EAE) mice revealed a strong correlation between Atg5 expression and clinical disability.Analysis of protein extracted from these cells confirmed both upregulation and post-translational modification of Atg5, the latter of which was positively correlated with EAE severity. Analysis of RNA extracted from T cells isolated by negative selection indicated that Atg5 expression was significantly elevated in individuals with active relapsing-remitting MS compared to non-diseased controls. Brain tissue sections from relapsing-remitting MS cases examined by immunofluorescent histochemistry suggested that encephalitogenic T cells are a source of Atg5 expression in MS brain samples. Together these data suggest that increased T cell expression of Atg5 may contribute to inflammatory demyelination in MS.

Definition of non-responders: biological markers

Identification of reliable biomarkers in multiple sclerosis patients would be highly desirable to help disease activity and progression monitoring, and evaluate response to treatments. The field has gradually shifted from the aim to find the perfect surrogate marker to the construction of composite markers with higher performances, taking advantage of the technologies allowing unbiased screening (i.e., microarrays, proteomics, etc.). Despite the fact that very interesting results have been produced, no approach has yet made it to the patient's bedside.

Reduction of free radicals in multiple sclerosis: effect of glatiramer acetate (Copaxone)

Free radicals have been found in high concentrations within inflammatory multiple sclerosis (MS) lesions. The superoxide anion (O(2)(-)) reacts rapidly with nitric oxide (NO), producing peroxynitrite (ONOO(-)). Glatiramer acetate (GA) is a specific MS immunomodulator that induces the synthesis of Th2 cytokines, and reduces the frequency of relapses and the formation of active brain lesions. Proinflammatory cytokines could play a role in free radicals production in the peripheral immune system as well as in the central nervous system (CNS). The effect of GA on iNOS, superoxide radicals (O(2)(-)) and 3-nitrotyrosine production by peripheral blood adherent mononuclear cells (PBAMs) was assessed. Our findings demonstrate that in vitro GA reduced spontaneous and LPS-induced iNOS, 3-nitrotyrosine, NO and O(2)(-) production, and that similar inhibition can be demonstrated ex vivo in mononuclear cells obtained from GA-treated patients. The inhibition of the production of free radicals in PBAMs may represent a new therapeutic mechanism against inflammation during MS.

Association of an EAAT2 polymorphism with higher glutamate concentration in relapsing multiple sclerosis

Glutamate excitotoxicity contributes to oligodendrocyte and tissue damage in multiple sclerosis (MS). Here, we have examined if glutamate homeostasis is altered in plasma from MS patients. We initially observed that plasma glutamate levels are elevated in MS patients as compared to control subjects. In addition, we have studied the presence of a polymorphism sited in the promoter of the glutamate transporter EAAT2 whose mutant genotype results in lower transporter expression. We found that the polymorphism is not associated with the risk to develop MS. However, it is associated with higher glutamate plasma levels during the course of a relapse. These findings suggest that glutamate homeostasis is compromised in MS and that carrying this mutation may contribute to this alteration in relapsing MS.

Interleukin-17 production in central nervous system-infiltrating T cells and glial cells is associated with active disease in multiple sclerosis

Recent findings in the animal model for multiple sclerosis (MS), experimental autoimmune encephalomyelitis, implicate a novel CD4+ T-cell subset (TH17), characterized by the secretion of interleukin-17 (IL-17), in disease pathogenesis. To elucidate its role in MS, brain tissues from patients with MS were compared to controls. We detected expression of IL-17 mRNA (by in situ hybridization) and protein (by immunohistochemistry) in perivascular lymphocytes as well as in astrocytes and oligodendrocytes located in the active areas of MS lesions. Further, we found a significant increase in the number of IL-17+ T cells in active rather than inactive areas of MS lesions. Specifically, double immunofluorescence showed that IL-17 immunoreactivity was detected in 79% of T cells in acute lesions, 73% in active areas of chronic active lesions, but in only 17% of those in inactive lesions and 7% in lymph node control tissue. CD8+, as well as CD4+, T cells were equally immunostained for IL-17 in MS tissues. Interestingly, and in contrast to lymph node T cells, no perivascular T cells showed FoxP3 expression, a marker of regulatory T cells, at any stage of MS lesions. These observations suggest an enrichment of both IL-17+CD4+ and CD8+ T cells in active MS lesions as well as an important role for IL-17 in MS pathogenesis, with some remarkable differences from the experimental autoimmune encephalomyelitis model.

Primary-progressive multiple sclerosis

About 10-15% of patients with multiple sclerosis (MS) present with gradually increasing neurological disability, a disorder known as primary-progressive multiple sclerosis (PPMS). Compared with relapse-onset multiple sclerosis, people with PPMS are older at onset and a higher proportion are men. Inflammatory white-matter lesions are less evident but diffuse axonal loss and microglial activation are seen in healthy-looking white matter, in addition to cortical demyelination, and quantitative MRI shows atrophy and intrinsic abnormalities in the grey matter and the white matter. Spinal cord atrophy corresponds to the usual clinical presentation of progressive spastic paraplegia. Although neuroaxonal degeneration seems to underlie PPMS, the pathogenesis and the extent to which immune-mediated mechanisms operate is unclear. MRI of the brain and spinal cord, and examination of the CSF, are important investigations for diagnosis; conventional immunomodulatory therapies, such as interferon beta and glatiramer acetate, are ineffective. Future research should focus on the clarification of the mechanisms of axonal loss, improvements to the design of clinical trials, and the development of effective neuroprotective treatments.

Intrathecal chitotriosidase and the outcome of multiple sclerosis

Activated macrophages are major effectors at all stages of lesion formation in multiple sclerosis (MS) brain. Here, we report that the macrophage enzyme chitotriosidase (Chit) is significantly elevated both in plasma and cerebrospinal fluid (CSF) of patients with MS as compared to healthy controls and other neurological patients (P<0.001). Furthermore, the Chit activity in blood significantly associates with the MS clinical course (higher in secondary progressive relative to relapsing-remitting, P=0.01) and the clinical severity as measured by Kurtkze's Expanded Disability Status Scale (P<0.001). Also, we found that Chit activity is compartmentalized in the central nervous system of early MS patients and that its CSF/plasma quotient, in the presence of a preserved albumin quotient, correlates with the extent of future clinical deterioration (r=0.91; P<0.001). These findings confirm that innate immunity, here represented by Chit, is clinically relevant in MS and allows, if confirmed, reconsidering novel MS therapeutic strategies specifically aimed at this branch of the immune response.

Lack of clinical manifestation of hereditary haemochromatosis in South African patients with multiple sclerosis

Caucasian South African patients with multiple sclerosis (MS) were screened for the most common hereditary haemochromatosis (HH) mutations, H63D and C282Y, in order to determine the impact of iron overload on clinical outcome of MS. DNA screening for mutations H63D and C282Y in 118 apparently unrelated MS patients did not reveal significant differences in allele frequencies in comparison with a control group from the same population. Of 17 MS patients heterozygous for C282Y, 3 had below normal and none had above normal transferrin saturation levels. One of the index MS patients, and subsequently also her sister who also has MS, tested positive for two copies of mutation C282Y. Determination of iron status revealed high serum ferritin and transferrin saturation levels in both patients. However, the index patient, being unaware of her C282Y status, had received treatment for iron deficiency in the past and her MS symptoms were less severe than those of her sister who has been wheelchair bound for the past 12 years and who did not take iron supplements. Lack of clinical manifestation of HH without any signs of organ damage in the C282Y homozygous MS patients is in accordance with a role of iron dysregulation in the aetiology of MS.

Analysis of viral and genetic factors in South African patients with multiple sclerosis

A significant association was previously demonstrated between multiple sclerosis (MS) and the functional 5'-(GT)n polymorphism in the promoter region of the SLC11A1 gene, which has been implicated in both autoimmune and infectious disease susceptibility. In the present study the role of viral infection was investigated in South African MS patients in relation to specific SLC11A1 genotypes. Serum and peripheral blood mononuclear cells (PBMC) of 49 MS patients, 33 close relatives and 39 unrelated controls previously genotyped for SLC11A1 were screened for the presence of MS-associated retrovirus (MSRV) and two herpes virus (HHV-6 and EBV) sequences. Expression of the pol gene of MSRV was detected in the serum RNA of 34/49 (69%) MS patients whilst absent in the serum of 39 unrelated healthy control individuals (p < 0.001) but was also present in 23/33 (70%) of the unaffected close relatives of the patients. HHV-6 and EBV sequences were detected in both MS patients and control individuals. The viral sequences were not confined to a specific SLC11A1 genotype. Infection with these viruses is excluded as the primary cause for MS in the South African population since no significant differences were detected between MS patients and their unaffected close family members.

Secondary progressive multiple sclerosis: current knowledge and future challenges

The secondary progressive phase of multiple sclerosis (MS), which is characterised by a steady accrual of fixed disability after an initial relapsing remitting course, is not clearly understood. Although there is no consensus on the mechanisms underlying such a transition to the progressive phase, epidemiological and neuroimaging studies indicate that it is probably driven by the high prevalence of neurodegenerative compared with inflammatory pathological changes. This notion is lent support by the limited efficacy of available immunomodulating and immunosuppressive treatment strategies, which seems to be further decreased in the late stages of secondary progressive MS. No established clinical or paraclinical predictors of the transition from relapsing remitting to secondary progressive MS have been described. However, the use of quantitative MRI-derived measures is warranted to monitor natural history studies and therapeutic trials of secondary progressive MS with increased reliability. In view of the small effects of immunomodulating and immunosuppressive treatments in preventing the transition to secondary progression, the development of treatments promoting neuroaxonal repair remains an important goal in this disease.