Sex-specific Tau methylation patterns and synaptic transcriptional alterations are associated with neural vulnerability during chronic neuroinflammation.

The molecular events underlying the transition from initial inflammatory flares to the progressive phase of multiple sclerosis (MS) remain poorly understood. Here, we report that the microtubule-associated protein (MAP) Tau exerts a gender-specific protective function on disease progression in the MS model experimental autoimmune encephalomyelitis (EAE). A detailed investigation of the autoimmune response in Tau-deficient mice excluded a strong immunoregulatory role for Tau, suggesting that its beneficial effects are presumably exerted within the central nervous system (CNS). Spinal cord transcriptomic data show increased synaptic dysfunctions and alterations in the NF-kB activation pathway upon EAE in Tau-deficient mice as compared to wildtype animals. We also performed the first comprehensive characterization of Tau post-translational modifications (PTMs) in the nervous system upon EAE. We report that the methylation levels of the conserved lysine residue K306 are significantly decreased in the chronic phase of the disease. By combining biochemical assays and molecular dynamics (MD) simulations, we demonstrate that methylation at K306 decreases the affinity of Tau for the microtubule network. Thus, the down-regulation of this PTM might represent a homeostatic response to enhance axonal stability against an autoimmune CNS insult. The results, altogether, position Tau as key mediator between the inflammatory processes and neurodegeneration that seems to unify many CNS diseases.

MRI phenotypes with high neurodegeneration are associated with peripheral blood B-cell changes.

Little is known about the mechanisms leading to neurodegeneration in multiple sclerosis (MS) and the role of peripheral blood cells in this neurodegenerative component. We aimed to correlate brain radiological phenotypes defined by high and low neurodegeneration with gene expression profiling of peripheral blood mononuclear cells (PBMC) from MS patients. Magnetic resonance imaging (MRI) scans from 64 patients with relapsing-remitting MS (RRMS) were classified into radiological phenotypes characterized by low (N = 27) and high (N = 37) neurodegeneration according to the number of contrast-enhancing lesions, the relative volume of non-enhancing black holes on T1-weighted images, and the brain parenchymal fraction. Gene expression profiling was determined in PBMC using microarrays, and validation of selected genes was performed by polymerase chain reaction (PCR). B-cell immunophenotyping was conducted by flow cytometry. Microarray analysis revealed the B-cell specific genes FCRL1, FCRL2, FCRL5 (Fc receptor-like 1, 2 and 5 respectively), and CD22 as the top differentially expressed genes between patients with high and low neurodegeneration. Levels for these genes were significantly down-regulated in PBMC from patients with MRI phenotypes characterized by high neurodegeneration and microarray findings were validated by PCR. In patients with high neurodegeneration, immunophenotyping showed a significant increase in the expression of the B-cell activation markers CD80 in naïve B cells (CD45+/CD19+/CD27-/IgD+), unswitched memory B cells (CD45+/CD19+/CD27+/IgD+), and switched memory B cells (CD45+/CD19+/CD27+/IgD-), and CD86 in naïve and switched memory B cells. These results suggest that RRMS patients with radiological phenotypes showing high neurodegeneration have changes in B cells characterized by down-regulation of B-cell-specific genes and increased activation status.

Aberrant STAT phosphorylation signaling in peripheral blood mononuclear cells from multiple sclerosis patients.

BACKGROUND: Multiple sclerosis (MS) is characterized by increased activation of peripheral blood mononuclear cells (PBMCs), linked to perturbations in the phosphorylation of signaling proteins. METHODS: We developed a phosphoflow cytometry protocol to assess the levels of 11 phosphorylated nuclear proteins at baseline conditions and after cell activation in distinct PBMC populations from 41 treatment-naïve relapsing-remitting (RR) MS subjects and 37 healthy controls, and in a second cohort of 9 untreated RRMS patients and 10 secondary progressive (SP) MS patients. Levels of HLA-ABC, HLA-E, and HLA-DR were also assessed. Phosphorylation levels of selected proteins were also assessed in mouse splenocytes isolated from myelin oligodendrocyte glycoprotein (MOG)35-55-induced experimental autoimmune encephalomyelitis (EAE). RESULTS: Modest differences were observed at baseline between patients and controls, with general lower phosphorylation levels in cells from affected individuals. Conversely, a dramatic increase in phosphorylated p38MAPK and STAT proteins was observed across all cell types in MS patients compared to controls after in vitro activation. A similar phosphorylation profile was observed in mouse lymphocytes primed in vivo with MOG. Furthermore, levels of all p-STAT proteins were found directly correlated with HLA expression in monocytes. Levels of phosphorylated proteins did not differ between relapsing-remitting and secondary progressive MS patients either in baseline conditions or after stimulation. Lastly, phosphorylation levels appear to be independent of the genotype. CONCLUSION: The response to IFN-α through STAT proteins signaling is strongly dysregulated in MS patients irrespective of disease stage. These findings suggest that the aberrant activation of this pathway could lead to changes in the expression of HLA molecules in antigen presenting cells, which are known to play important roles in the regulation of the immune response in health and disease.

Multiple sclerosis genetics.

A broad scientific consensus has emerged linking multiple sclerosis (MS) risk to multiple independent and interacting DNA variants that are relatively frequent in the population and act in concert with environmental exposures. The multifactorial, polygenic model of heritability provided the rationale and impetus to pursue genome-wide association studies (GWAS), which have been highly successful in uncovering genetic variants influencing susceptibility. Over 200 loci have been firmly associated with MS susceptibility. The main association signal genome-wide maps to the major histocompatibility complex ( MHC) gene cluster in chromosome 6p21. This association has been observed across all populations studied. However, a significant proportion of MS heritability remains unexplained. Decoding the genetics of MS represents a long-standing and important research goal in this disease, as the demonstration of even modest functional genomic effects on risk or the course of MS is likely to reveal fundamental disease mechanisms and possibly yield new therapeutic opportunities.

Protein-Based Classifier to Predict Conversion from Clinically Isolated Syndrome to Multiple Sclerosis.

Multiple sclerosis is an inflammatory, demyelinating, and neurodegenerative disease of the central nervous system. In most patients, the disease initiates with an episode of neurological disturbance referred to as clinically isolated syndrome, but not all patients with this syndrome develop multiple sclerosis over time, and currently, there is no clinical test that can conclusively establish whether a patient with a clinically isolated syndrome will eventually develop clinically defined multiple sclerosis. Here, we took advantage of the capabilities of targeted mass spectrometry to establish a diagnostic molecular classifier with high sensitivity and specificity able to differentiate between clinically isolated syndrome patients with a high and a low risk of developing multiple sclerosis. Based on the combination of abundances of proteins chitinase 3-like 1 and ala-ß-his-dipeptidase in cerebrospinal fluid, we built a statistical model able to assign to each patient a precise probability of conversion to clinically defined multiple sclerosis. Our results are of special relevance for patients affected by multiple sclerosis as early treatment can prevent brain damage and slow down the disease progression.

PML risk stratification using anti-JCV antibody index and L-selectin.

BACKGROUND: Natalizumab treatment is associated with progressive multifocal leukoencephalopathy (PML) development. Treatment duration, prior immunosuppressant use, and JCV serostatus are currently used for risk stratification, but PML incidence stays high. Anti-JCV antibody index and L-selectin (CD62L) have been proposed as additional risk stratification parameters. OBJECTIVE: This study aimed at verifying and integrating both parameters into one algorithm for risk stratification. METHODS: Multicentric, international cohorts of natalizumab-treated MS patients were assessed for JCV index (1921 control patients and nine pre-PML patients) and CD62L (1410 control patients and 17 pre-PML patients). RESULTS: CD62L values correlate with JCV serostatus, as well as JCV index values. Low CD62L in natalizumab-treated patients was confirmed and validated as a biomarker for PML risk with the risk factor "CD62L low" increasing a patient's relative risk 55-fold (p < 0.0001). Validation efforts established 86% sensitivity/91% specificity for CD62L and 100% sensitivity/59% specificity for JCV index as predictors of PML. Using both parameters identified 1.9% of natalizumab-treated patients in the reference center as the risk group. CONCLUSIONS: Both JCV index and CD62L have merit for risk stratification and share a potential biological relationship with implications for general PML etiology. A risk algorithm incorporating both biomarkers could strongly reduce PML incidence.

Chitinase 3-like 1: prognostic biomarker in clinically isolated syndromes.

Chitinase 3-like 1 (CHI3L1) has been proposed as a biomarker associated with the conversion to clinically definite multiple sclerosis in patients with clinically isolated syndromes, based on the finding of increased cerebrospinal fluid CHI3L1 levels in clinically isolated syndrome patients who later converted to multiple sclerosis compared to those who remained as clinically isolated syndrome. Here, we aimed to validate CHI3L1 as a prognostic biomarker in a large cohort of patients with clinically isolated syndrome. This is a longitudinal cohort study of clinically isolated syndrome patients with clinical, magnetic resonance imaging, and cerebrospinal fluid data prospectively acquired. A total of 813 cerebrospinal fluid samples from patients with clinically isolated syndrome were recruited from 15 European multiple sclerosis centres. Cerebrospinal fluid CHI3L1 levels were measured by enzyme-linked immunosorbent assay. Multivariable Cox regression models were used to investigate the association between cerebrospinal fluid CHI3L1 levels and time to conversion to multiple sclerosis and time to reach Expanded Disability Status Scale 3.0. CHI3L1 levels were higher in patients who converted to clinically definite multiple sclerosis compared to patients who continued as clinically isolated syndrome (P = 8.1 × 10(-11)). In the Cox regression analysis, CHI3L1 levels were a risk factor for conversion to multiple sclerosis (hazard ratio = 1.7; P = 1.1 × 10(-5) using Poser criteria; hazard ratio = 1.6; P = 3.7 × 10(-6) for McDonald criteria) independent of other covariates such as brain magnetic resonance imaging abnormalities and presence of cerebrospinal fluid oligoclonal bands, and were the only significant independent risk factor associated with the development of disability (hazard ratio = 3.8; P = 2.5 × 10(-8)). High CHI3L1 levels were associated with shorter time to multiple sclerosis (P = 3.2 × 10(-9) using Poser criteria; P = 5.6 × 10(-11) for McDonald criteria) and more rapid development of disability (P = 1.8 × 10(-10)). These findings validate cerebrospinal fluid CHI3L1 as a biomarker associated with the conversion to multiple sclerosis and development of disability and reinforce the prognostic role of CHI3L1 in patients with clinically isolated syndrome. We propose that determining cerebrospinal fluid chitinase 3-like 1 levels at the time of a clinically isolated syndrome event will help identify those patients with worse disease prognosis.

Breast regression protein-39 is not required for experimental autoimmune encephalomyelitis induction.

Increasing evidence points to a role for chitinase 3-like 1 (CHI3L1) in multiple sclerosis (MS). Here, we aimed to explore the potential involvement of CHI3L1 in the animal model of MS, experimental autoimmune encephalomyelitis (EAE). EAE was induced by immunization with MOG 35-55 peptide in wild-type (WT) and knock-out (KO) mice for breast regression protein 39 (BRP-39), the mouse homologue of human CHI3L1. Immunological responses in splenocytes were assessed by means of polyclonal and antigen-specific proliferation assays. Central nervous system pathology and chitinase gene expression were also investigated. BRP-39 expression was increased in WT MOG 35-55-immunized mice compared to saline-immunized controls. No differences were found between WT and BRP-39 KO mice regarding EAE clinical course, day of disease onset, mortality rate, splenocyte proliferative responses or histopathological findings. These results do not support a role of BRP-39 in the pathogenesis of EAE.

Validation of semaphorin 7A and ala-ß-his-dipeptidase as biomarkers associated with the conversion from clinically isolated syndrome to multiple sclerosis.

BACKGROUND: In a previous proteomics study using pooled cerebrospinal fluid (CSF) samples, we proposed apolipoprotein AI, apolipoprotein AIV, vitronectin, plasminogen, semaphorin 7A, and ala-ß-his-dipeptidase as candidate biomarkers associated with the conversion to clinically definite multiple sclerosis (CDMS) in patients with clinically isolated syndromes (CIS). Here, we aimed to validate these results in individual CSF samples using alternative techniques. METHODS: In a first replication study, levels of apolipoproteins AI and AIV, vitronectin, and plasminogen were measured by ELISA in CSF and serum of 56 CIS patients (29 patients who converted to CDMS (MS converters) and 27 patients who remained with CIS during follow-up (MS non-converters)) and 26 controls with other neurological disorders. Semaphorin 7A and ala-ß-his-dipeptidase levels were determined by selected reaction monitoring (SRM) in CSF of 36 patients (18 MS converters, 18 non-converters) and 20 controls. In a second replication study, apolipoprotein AI levels were measured by ELISA in CSF of 74 CIS patients (47 MS converters, 27 non-converters) and 50 individual controls, and levels of semaphorin 7A and ala-beta-his-dipeptidase were determined by SRM in 49 patients (24 MS converters, 25 non-converters) and 22 controls. RESULTS: CSF levels of apolipoprotein AI were increased (P = 0.043) and levels of semaphorin 7A and ala-ß-his-dipeptidase decreased (P = 4.4 × 10(-10) and P = 0.033 respectively) in MS converters compared to non-converters. No significant differences were found in serum levels for apolipoproteins AI and AIV, vitronectin, and plasminogen. Findings with semaphorin 7A and ala-ß-his-dipeptidase were also validated in the second replication study, and CSF levels for these two proteins were again decreased in MS converters versus non-converters (P = 1.2 × 10(-4) for semaphorin 7A; P = 3.7 × 10(-8) for ala-ß-his-dipeptidase). Conversely, apolipoprotein AI findings were not replicated and CSF levels for this protein did not significantly differ between groups. Furthermore, CSF semaphorin 7A levels were negatively associated with the number of T2 lesions at baseline and one-year follow-up. CONCLUSIONS: These results validate previous findings for semaphorin 7A and ala-ß-his-dipeptidase, and suggest that these proteins play a role as CSF biomarkers associated with the conversion to CDMS in CIS patients.

Identification of Candidate Immunodominant Epitopes and Their HLA-Binding Prediction on BK Polyomavirus Proteins in Healthy Donors.

BK polyomavirus infection is an important cause of graft loss in transplant patients, however, currently available therapies lack effectiveness against this pathogen. Identification of immunological targets for potential treatments is therefore necessary. The aim of this study was to predict candidates of immunodominant epitopes within four BK virus proteins (VP1, VP2, VP3 and LTA) using PBMCs from 44 healthy donors. We used the ELISpot epitope mapping method to evaluate the T-cell response, and HLA-peptide binding was predicted using the NetMHCpan algorithm. A total of 11 potential peptides were selected for VP1, 3 for VP2/VP3 and 13 for LTA. Greater reactivity was observed for VP1 and LTA proteins compared with VP2/VP3. Most of the peptides selected as potential immunodominant candidates were restricted towards several HLA class I and II alleles, with predominant HLA class I binding by computational predictions. Based on these findings, the sequences of the selected immunodominant epitopes candidates and their corresponding HLA restrictions could contribute to the optimisation of functional assays and aid in the design and improvement of immunotherapy strategies against BK virus infections.

Cerebrospinal fluid chitinase 3-like 1 levels are associated with conversion to multiple sclerosis.

In most patients with multiple sclerosis, the disease initiates with a first attack or clinically isolated syndrome. At this phase, magnetic resonance imaging is an important predictor of conversion to multiple sclerosis. With the exception of oligoclonal bands, the role of other biomarkers in patients with clinically isolated syndrome is controversial. In the present study, we aimed to identify proteins associated with conversion to multiple sclerosis in patients with clinically isolated syndrome. We applied a mass spectrometry-based proteomic approach (isobaric labelling) to previously collected pooled cerebrospinal fluid samples from patients with clinically isolated syndrome, who subsequently converted to clinically definite multiple sclerosis (n=30) and patients who remained as having clinically isolated syndrome (n=30). Next, three of the most represented differentially expressed proteins, i.e. ceruloplasmin, vitamin D-binding protein and chitinase 3-like 1 were selected for validation in individual cerebrospinal fluid samples by enzyme-linked immunosorbent assay. Only chitinase 3-like 1 was validated and cerebrospinal fluid levels were increased in patients who converted to clinically definite multiple sclerosis compared with patients who continued as clinically isolated syndrome (P=0.00002) and controls (P=0.012). High cerebrospinal fluid levels of chitinase 3-like 1 significantly correlated with the number of gadolinium enhancing lesions and the number of T2 lesions observed in brain magnetic resonance imaging scans performed at baseline, and were associated with disability progression during follow-up and shorter time to clinically definite multiple sclerosis (log-rank P-value=0.003). Cerebrospinal fluid chitinase 3-like 1 levels were also measured in a second validation clinically isolated syndrome cohort and found to be increased in patients who converted to multiple sclerosis compared with patients who remained as having clinically isolated syndrome (P=0.018). Our results indicate that patients who will convert to clinically definite multiple sclerosis could be distinguished from those patients who will remain as clinically isolated syndrome by proteomic analysis of cerebrospinal fluid samples. Although protein levels are also increased in other disorders characterized by chronic inflammation, chitinase 3-like 1 may serve as a prognostic biomarker for conversion to multiple sclerosis and development of disability which may help to improve the understanding of the aetiopathogenesis in the early stages of multiple sclerosis.

Distinctive waves of innate immune response in the retina in experimental autoimmune encephalomyelitis.

Neurodegeneration mediates neurological disability in inflammatory demyelinating diseases of the CNS. The role of innate immune cells in mediating this damage has remained controversial with evidence for destructive and protective effects. This has complicated efforts to develop treatment. The time sequence and dynamic evolution of the opposing functions are especially unclear. Given limits of in vivo monitoring in human diseases such as multiple sclerosis (MS), animal models are warranted to investigate the association and timing of innate immune activation with neurodegeneration. Using noninvasive in vivo retinal imaging of experimental autoimmune encephalitis (EAE) in CX3CR1GFP/+-knock-in mice followed by transcriptional profiling, we are able to show 2 distinct waves separated by a marked reduction in the number of innate immune cells and change in cell morphology. The first wave is characterized by an inflammatory phagocytic phenotype preceding the onset of EAE, whereas the second wave is characterized by a regulatory, antiinflammatory phenotype during the chronic stage. Additionally, the magnitude of the first wave is associated with neuronal loss. Two transcripts identified - growth arrest-specific protein 6 (GAS6) and suppressor of cytokine signaling 3 (SOCS3) - might be promising targets for enhancing protective effects of microglia in the chronic phase after initial injury.

Characterization of a Cytomegalovirus-Specific T Lymphocyte Product Obtained Through a Rapid and Scalable Production Process for Use in Adoptive Immunotherapy.

Immunosuppressed patients are susceptible to virus reactivation or de novo infection. Adoptive immunotherapy, based on virus-specific T lymphocytes (VST), can prevent or treat viral diseases. However, donor availability, HLA-compatibility restrictions, high costs, and time required for the production of personalized medicines constitute considerable limitations to this treatment. Ex vivo rapid and large-scale expansion of VST, compliant with current good manufacturing practice (cGMP) standards, with an associated cell donor registry would overcome these limitations. This study aimed to characterize a VST product obtained through an expansion protocol transferable to cGMP standards. Antigenic stimulus consisted of cytomegalovirus (CMV) pp65 peptide pool-pulsed autologous dendritic cells (DCs) derived from monocytes. G-Rex technology, cytokines IL-2, IL-7, and IL-15, and anti-CD3 and anti-CD28 antibodies were used for culture. At day 14 of cell culture, the final product was characterized regarding T cell subsets, specificity, and functionality. The final product, comprised mainly CD4+ and CD8+ T lymphocytes (49.2 ± 24.7 and 42.3 ± 25.2, respectively). The culture conditions made it possible to achieve at least a 98.89-fold increase in pp65-specific CD3+ IFN-γ+ cells. These cells were specific, as pp65-specific cytotoxicity was demonstrated. Additionally, in complete HLA mismatch and without the presence of pp65, alloreactivity resulted in <5% cell lysis. In conclusion, a cGMP scalable process for the generation of a large number of doses of CMV-specific cytotoxic T cells was successfully performed.

Association Between Serum Neurofilament Light Chain Levels and Long-term Disease Course Among Patients With Multiple Sclerosis Followed up for 12 Years.

IMPORTANCE: Blood sample-based biomarkers that are associated with clinically meaningful outcomes for patients with multiple sclerosis (MS) have not been developed. OBJECTIVE: To evaluate the potential of serum neurofilament light chain (sNFL) measurements as a biomarker of disease activity and progression in a longitudinal MS data set. DESIGN, SETTING, AND PARTICIPANTS: Single-center, ongoing, prospective observational cohort study of 607 patients with MS from the longitudinal EPIC (Expression, Proteomics, Imaging, Clinical) study at the University of California, San Francisco from July 1, 2004, through August 31, 2017. Clinical evaluations and sample collection were performed annually for 5 years, then at different time points for up to 12 years, with a median follow-up duration of 10 (interquartile range, 7-11) years. Serum NFL levels were measured using a sensitive single molecule array platform and compared with clinical and magnetic resonance imaging variables with the use of univariable and multivariable analyses. MAIN OUTCOMES AND MEASURES: The main outcomes were disability progression defined as clinically significant worsening on the Expanded Disability Status Scale (EDSS) score and brain fraction atrophy. RESULTS: Mean (SD) age of the 607 study participants at study entry was 42.5 (9.8) years; 423 (69.7%) were women; and all participants were of non-Hispanic European descent. Of 3911 samples sequentially collected, 3904 passed quality control for quantification of sNFL. Baseline sNFL levels showed significant associations with EDSS score (ß, 1.080; 95% CI, 1.047-1.114; P < .001), MS subtype (ß, 1.478; 95% CI, 1.279-1.707; P < .001), and treatment status (ß, 1.120; 95% CI, 1.007-1.245; P = .04). A significant interaction between EDSS worsening and change in levels of sNFL over time was found (ß, 1.015; 95% CI, 1.007-1.023; P < .001). Baseline sNFL levels alone were associated with approximately 11.6% of the variance in brain fraction atrophy at year 10. In a multivariable analysis that considered sex, age, and disease duration, baseline sNFL levels were associated with 18.0% of the variance in brain fraction atrophy at year 10. After 5 years' follow-up, active treatment was associated with lower levels of sNFL, with high-potency treatments associated with the greater decreases in sNFL levels compared with platform therapies (high-potency vs untreated: ß, 0.946; 95% CI, 0.915-0.976; P < .001; high-potency vs platform: ß, 0.972; 95% CI, 0.948-0.998; P = .04). CONCLUSIONS AND RELEVANCE: This study found that statistically significant associations of sNFL with relevant clinical and neuroimaging outcomes in MS were confirmed and extended, supporting the potential of sNFL as an objective surrogate of ongoing MS disease activity. In this data set of patients with MS who received early treatment, the prognostic power of sNFL for relapse activity and long-term disability progression was limited. Further prospective studies are necessary to assess the assay's utility for decision-making in individual patients.

Peripheral blood non-MAIT CD8+CD161hi cells are decreased in relapsing-remitting multiple sclerosis patients treated with interferon beta.

CD8+CD161hi cells, comprising MAIT and non-MAIT cells, have been involved in multiple sclerosis (MS) pathogenesis. Here, we investigated the frequency of CD8+CD161hi, MAIT and non-MAIT cells by flow cytometry in peripheral blood samples from 41 untreated MS patients, 48 patients receiving disease modifying therapies, and 17 healthy controls (HC). IFNß treatment was associated with a decrease in the frequency of Tc17 cells compared to untreated patients (p=0.019). No significant differences were observed between untreated MS patients and HC for any of the study cell populations. These results suggest previously unknown mechanisms of action of IFNß.

Levels of soluble TNF-RII are increased in serum of patients with primary progressive multiple sclerosis.

The levels of soluble tumor necrosis factor receptor II (sTNF-RII) were determined in serum of 161 untreated multiple sclerosis (MS) patients with different clinical forms and 46 healthy controls (HC) by ELISA. Our results show that serum sTNF-RII levels were significantly increased in patients with primary progressive MS (PPMS) compared with other MS forms and HC. Although sTNF-RII levels significantly increased over a 2-year follow-up period in a subgroup of PPMS patients, they could not discriminate between patients with and without disability progression. Additional studies are needed to further implicate sTNF-RII in patients with PPMS.

Circulating levels of soluble apoptosis-related molecules in patients with multiple sclerosis.

Evidence exists that apoptotic elimination of autoreactive T lymphocytes is defective in multiple sclerosis (MS). Here, we measured serum levels of soluble forms of Fas (sFas), Fas ligand (sFasL) and TNF-related apoptosis-inducing ligand (sTRAIL) in 38 healthy controls (HC) and 92 untreated MS patients with different clinical forms and activity phases of the disease by immunoassay. Serum levels of sFas, sFasL and sTRAIL did not differ between MS patients and HC. sTRAIL levels were significantly decreased in RRMS during relapses. These findings support a role of TRAIL in the pathogenesis of MS, especially during the acute phases of the disease.