Longitudinal study of antimyelin T-cell reactivity in relapsing-remitting multiple sclerosis: association with clinical and MRI activity

25 Hydroxyvitamin D and Cytokine Profile in Patients With Relapsing-Remitting Multiple Sclerosis

In experimental allergic encephalomyelitis, the severity of the deficiency is associated with the loss of axons, and it is likely that cytotoxic T-cells 8 (CD8 T) play an important role. In relapsing-remitting multiple sclerosis, there is a correlation between the inflammatory activity in the lesion and the transection of axons. To understand the pathological mechanisms, it is important to evaluate the changes in serum concentrations of pro- and anti-inflammatory cytokines during the disease course. A total of 46 patients and 40 healthy individuals participated in an open-label, prospective, case-control study from 2012 to 2014. The serum concentrations of cytokines were measured using enzyme-linked immunosorbent assay (ELISA). An immune imbalance was observed during relapse and remission phases compared to the control group. During relapse, the levels of interferon-gamma (IFN-γ) were significantly higher compared to those in remission (p=0.017). During remission, there was an improvement in the deficiency (p<0.001), and the anti-inflammatory cytokines transforming growth factor-beta (TGF-β) and interleukin 4 (IL4) increased compared to those in relapse (p=0.006; p=0.009). A correlation was found between the serum concentrations of tumor necrosis factor-alpha (TNF-α) and Expanded Disability Status Scale (EDSS) during relapse (correlation coefficient: 0.301; significance (Sig.) (2-tailed 0.042). During the exacerbation, there was a moderate relationship between interleukin 17 (IL17) and 25-hydroxyvitamin D (25(OH)D) (P (p-value (probability value) = 0.02)). TNF-α, IFN-γ, IL17, and TGF-β serum levels are criteria for evaluating immune inflammatory activity during relapse and remission periods.

A Scoping Review on Body Fluid Biomarkers for Prognosis and Disease Activity in Patients with Multiple Sclerosis

Multiple sclerosis (MS) is a complex demyelinating disease of the central nervous system, presenting with different clinical forms, including clinically isolated syndrome (CIS), which is a first clinical episode suggestive of demyelination. Several molecules have been proposed as prognostic biomarkers in MS. We aimed to perform a scoping review of the potential use of prognostic biomarkers in MS clinical practice. We searched MEDLINE up to 25 November 2021 for review articles assessing body fluid biomarkers for prognostic purposes, including any type of biomarkers, cell types and tissues. Original articles were obtained to confirm and detail the data reported by the review authors. We evaluated the reliability of the biomarkers based on the sample size used by various studies. Fifty-two review articles were included. We identified 110 molecules proposed as prognostic biomarkers. Only six studies had an adequate sample size to explore the risk of conversion from CIS to MS. These confirm the role of oligoclonal bands, immunoglobulin free light chain and chitinase CHI3L1 in CSF and of serum vitamin D in the prediction of conversion from CIS to clinically definite MS. Other prognostic markers are not yet explored in adequately powered samples. Serum and CSF levels of neurofilaments represent a promising biomarker.

The Worm-Specific Immune Response in Multiple Sclerosis Patients Receiving Controlled Trichuris suis Ova Immunotherapy

Considering their potent immunomodulatory properties, therapeutic applications of Trichuris suis ova (TSO) are studied as potential alternative treatment of autoimmune disorders like multiple sclerosis (MS), rheumatoid arthritis (RA), or inflammatory bowel disease (IBD). Clinical phase 1 and 2 studies have demonstrated TSO treatment to be safe and well tolerated in MS patients, however, they reported only modest clinical efficacy. We therefore addressed the cellular and humoral immune responses directed against parasite antigens in individual MS patients receiving controlled TSO treatment (2500 TSO p.o. every 2 weeks for 12 month). Peripheral blood mononuclear cells (PBMC) of MS patients treated with TSO (n = 5) or placebo (n = 6) were analyzed. A continuous increase of serum IgG and IgE antibodies specific for T. suis excretory/secretory antigens was observed up to 12 months post-treatment. This was consistent with mass cytometry analysis identifying an increase of activated HLA-DR^high plasmablast frequencies in TSO-treated patients. While stable and comparable frequencies of total CD4⁺ and CD8⁺ T cells were detected in placebo and TSO-treated patients over time, we observed an increase of activated HLA-DR⁺CD4⁺ T cells in TSO-treated patients only. Frequencies of Gata3⁺ Th2 cells and Th1/Th2 ratios remained stable during TSO treatment, while Foxp3⁺ Treg frequencies varied greatly between individuals. Using a T. suis antigen-specific T cell expansion assay, we also detected patient-to-patient variation of antigen-specific T cell recall responses and cytokine production. In summary, MS patients receiving TSO treatment established a T. suis-specific T- and B-cell response, however, with varying degrees of T cell responses and cellular functionality across individuals, which might account for the overall miscellaneous clinical efficacy in the studied patients.

Cytomegalovirus infection exacerbates autoimmune mediated neuroinflammation

Cytomegalovirus (CMV) is a latent virus which causes chronic activation of the immune system. Here, we demonstrate that cytotoxic and pro-inflammatory CD4⁺CD28^null T cells are only present in CMV seropositive donors and that CMV-specific Immunoglobulin (Ig) G titers correlate with the percentage of these cells. In vitro stimulation of peripheral blood mononuclear cells with CMVpp65 peptide resulted in the expansion of pre-existing CD4⁺CD28^null T cells. In vivo, we observed de novo formation, as well as expansion of CD4⁺CD28^null T cells in two different chronic inflammation models, namely the murine CMV (MCMV) model and the experimental autoimmune encephalomyelitis (EAE) model for multiple sclerosis (MS). In EAE, the percentage of peripheral CD4⁺CD28^null T cells correlated with disease severity. Pre-exposure to MCMV further aggravated EAE symptoms, which was paralleled by peripheral expansion of CD4⁺CD28^null T cells, increased splenocyte MOG reactivity and higher levels of spinal cord demyelination. Cytotoxic CD4⁺ T cells were identified in demyelinated spinal cord regions, suggesting that peripherally expanded CD4⁺CD28^null T cells migrate towards the central nervous system to inflict damage. Taken together, we demonstrate that CMV drives the expansion of CD4⁺CD28^null T cells, thereby boosting the activation of disease-specific CD4⁺ T cells and aggravating autoimmune mediated inflammation and demyelination.

Genomics implicates adaptive and innate immunity in Alzheimer's and Parkinson's diseases

OBJECTIVES

We assessed the current genetic evidence for the involvement of various cell types and tissue types in the etiology of neurodegenerative diseases, especially in relation to the neuroinflammatory hypothesis of neurodegenerative diseases.

METHODS

We obtained large-scale genome-wide association study (GWAS) summary statistics from Parkinson's disease (PD), Alzheimer's disease (AD), and amyotrophic lateral sclerosis (ALS). We used multiple sclerosis (MS), an autoimmune disease of the central nervous system, as a positive control. We applied stratified LD score regression to determine if functional marks for cell type and tissue activity, and gene-set lists were enriched for genetic heritability. We compared our results to those from two gene-set enrichment methods (Ingenuity Pathway Analysis and enrichr).

RESULTS

There were no significant heritability enrichments for annotations marking genes active within brain regions, but there were significant heritability enrichments for annotations marking genes active within cell types that form part of both the innate and adaptive immune systems. We found this for MS (as expected) and also for AD and PD. The strongest signals were from the adaptive immune system (e.g., T cells) for PD, and from both the adaptive (e.g., T cells) and innate (e.g., CD14: a marker for monocytes, and CD15: a marker for neutrophils) immune systems for AD. Annotations from the liver were also significant for AD. Pathway analysis provided complementary results.

INTERPRETATION

For AD and PD, we found significant enrichment of heritability in annotations marking gene activity in immune cells.

Immunopathology of Japanese macaque encephalomyelitis is similar to multiple sclerosis

Japanese macaque encephalomyelitis (JME) is an inflammatory demyelinating disease that occurs spontaneously in a colony of Japanese macaques (JM) at the Oregon National Primate Research Center. Animals with JME display clinical signs resembling multiple sclerosis (MS), and magnetic resonance imaging reveals multiple T2-weighted hyperintensities and gadolinium-enhancing lesions in the central nervous system (CNS). Here we undertook studies to determine if JME possesses features of an immune-mediated disease in the CNS. Comparable to MS, the CNS of animals with JME contain active lesions positive for IL-17, CD4+ T cells with Th1 and Th17 phenotypes, CD8+ T cells, and positive CSF findings.

Stage-specific immune dysregulation in multiple sclerosis

A large body of data indicates that multiple sclerosis (MS) is an autoimmune disease which is initiated by CD4(+) T-helper 1 (Th1) and Th17 cells that are reactive against proteins in the myelin sheath. MS typically begins with a relapsing-remitting course, punctuated by clinical exacerbations associated with the development of focal inflammatory lesions in central nervous system white matter, followed by a secondary progressive (SP) phase, characterized by a gradual accumulation of neurological disability associated with widespread microglial activation and axonal loss. The molecular and cellular basis for this transition is unclear, and the role of inflammation during the SP stage is a subject of active debate. As of now, no immunological biomarkers have been identified in MS that are predictive of the clinical course or therapeutic responsiveness to disease-modifying agents, or that correlate with new lesion development, cumulative lesion load, or degree of disability. The discovery of such biomarkers would greatly facilitate clinical management and provide power for smaller and shorter clinical trials. In this article, we discuss the literature on immunological biomarkers in MS with a focus on stage-specific differences and similarities.

Human platelet antigen (HPA)-1a peptides do not reliably suppress anti-HPA-1a responses using a humanized severe combined immunodeficiency (SCID) mouse model

Fetal and neonatal alloimmune thrombocytopenia (FNAIT) occurs most frequently when human platelet antigen (HPA)-1a-positive fetal platelets are destroyed by maternal HPA-1a immunoglobulin (Ig)G antibodies. Pregnancies at risk are treated by administration of high-dose intravenous Ig (IVIG) to women, but this is expensive and often not well tolerated. Peptide immunotherapy may be effective for ameliorating some allergic and autoimmune diseases. The HPA-1a/1b polymorphism is Leu/Pro33 on β3 integrin (CD61), and the anti-HPA-1a response is restricted to HPA-1b1b and HLA-DRB3*0101-positive pregnant women with an HPA-1a-positive fetus. We investigated whether or not HPA-1a antigen-specific peptides that formed the T cell epitope could reduce IgG anti-HPA-1a responses, using a mouse model we had developed previously. Peripheral blood mononuclear cells (PBMC) in blood donations from HPA-1a-immunized women were injected intraperitoneally (i.p.) into severe combined immunodeficient (SCID) mice with peptides and HPA-1a-positive platelets. Human anti-HPA-1a in murine plasma was quantitated at intervals up to 15 weeks. HPA-1a-specific T cells in PBMC were identified by proliferation assays. Using PBMC of three donors who had little T cell reactivity to HPA-1a peptides in vitro, stimulation of anti-HPA-1a responses by these peptides occurred in vivo. However, with a second donation from one of these women which, uniquely, had high HPA-1a-specific T cell proliferation in vitro, marked suppression of the anti-HPA-1a response by HPA-1a peptides occurred in vivo. HPA-1a peptide immunotherapy in this model depended upon reactivation of HPA-1a T cell responses in the donor. For FNAIT, we suggest that administration of antigen-specific peptides to pregnant women might cause either enhancement or reduction of pathogenic antibodies.

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

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

Diminished Th17 (not Th1) responses underlie multiple sclerosis disease abrogation after hematopoietic stem cell transplantation

OBJECTIVE

To define changes in phenotype and functional responses of reconstituting T cells in patients with aggressive multiple sclerosis (MS) treated with ablative chemotherapy and autologous hematopoietic stem cell transplantation (HSCT).

METHODS

Clinical and brain magnetic resonance imaging measures of disease activity were monitored serially in patients participating in the Canadian MS HSCT Study. Reconstitution kinetics of immune-cell subsets were determined by flow cytometry, whereas thymic function was assessed using T-cell receptor excision circle analyses as well as flow cytometry measurements of CD31+ recent thymic emigrants (RTEs). Functional assays were performed to track central nervous system-autoreactive antigen-specific T-cell responses, and the relative capacity to generate Th1, Th17, or Th1/17 T-cell responses.

RESULTS

Complete abrogation of new clinical relapses and new focal inflammatory brain lesions throughout the 2 years of immune monitoring following treatment was associated with sustained decrease in naive T cells, in spite of restoration of both thymic function and release of RTEs during reconstitution. Re-emergence as well as in vivo expansion of autoreactive T cells to multiple myelin targets was evident in all patients studied. The reconstituted myelin-specific T cells exhibited the same Th1 and Th2 responses as preablation myelin-reactive T cells. In contrast, the post-therapy T-cell repertoire exhibited a significantly diminished capacity for Th17 responses.

INTERPRETATION

Our results indicate that diminished Th17 and Th1/17 responses, rather than Th1 responses, are particularly relevant to the abrogation of new relapsing disease activity observed in this cohort of patients with aggressive MS following chemoablation and HSCT.

Expression of scavenger receptor A on antigen presenting cells is important for CD4+ T-cells proliferation in EAE mouse model

BACKGROUND

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system (CNS) characterized by damage to the neuronal myelin sheath. One of the key effectors for inflammatory injury is the antigen-presenting cell (APC). The class A scavenger receptor (SRA), constitutively expressed by APCs, such as macrophages and dendritic cells in peripheral tissues and the CNS, was shown to play a role in the phagocytosis of myelin; however, the role of SRA in the development of experimental autoimmune encephalomyelitis (EAE) and autoimmune reaction in the periphery has not yet been studied.

METHODS

We investigated EAE progression in wild-type (WT) vs. SRA-/- mice using clinical score measurements and characterized CNS pathology using staining. Furthermore, we assessed SRA role in mediating anti myelin pro-inflammatory response in cell cultures.

RESULTS

We discovered that EAE progression and CNS demyelination were significantly reduced in SRA-/- mice compared to WT mice. In addition, there was a reduction of infiltrating peripheral immune cells, such as T cells and macrophages, in the CNS lesion of SRA-/- mice, which was associated with reduced astrogliosis. Immunological assessment showed that SRA deficiency resulted in significant reduction of pro-inflammatory cytokines that play a major role in EAE progression, such as IL-2, IFN-gamma, IL-17 and IL-6. Furthermore, we discovered that SRA-/- APCs showed impairments in activation and in their ability to induce pro-inflammatory CD4+ T cell proliferation.

CONCLUSION

Expression of SRA on APCs is important for CD4+ T-cells proliferation in EAE mouse model. Further studies of SRA-mediated cellular pathways in APCs may offer useful insights into the development of MS and other autoimmune diseases, providing future avenues for therapeutic intervention.

VCAM-1-targeted magnetic resonance imaging reveals subclinical disease in a mouse model of multiple sclerosis

Diagnosis of multiple sclerosis (MS) currently requires lesion identification by gadolinium (Gd)-enhanced or T(2)-weighted magnetic resonance imaging (MRI). However, these methods only identify late-stage pathology associated with blood-brain barrier breakdown. There is a growing belief that more widespread, but currently undetectable, pathology is present in the MS brain. We have previously demonstrated that an anti-VCAM-1 antibody conjugated to microparticles of iron oxide (VCAM-MPIO) enables in vivo detection of VCAM-1 by MRI. Here, in an experimental autoimmune encephalomyelitis (EAE) mouse model of MS, we have shown that presymptomatic lesions can be quantified using VCAM-MPIO when they are undetectable by Gd-enhancing MRI. Moreover, in symptomatic animals VCAM-MPIO binding was present in all regions showing Gd-DTPA enhancement and also in areas of no Gd-DTPA enhancement, which were confirmed histologically to be regions of leukocyte infiltration. VCAM-MPIO binding correlated significantly with increasing disability. Negligible MPIO-induced contrast was found in either EAE animals injected with an equivalent nontargeted contrast agent (IgG-MPIO) or in control animals injected with the VCAM-MPIO. These findings describe a highly sensitive molecular imaging tool that may enable detection of currently invisible pathology in MS, thus accelerating diagnosis, guiding treatment, and enabling quantitative disease assessment.

T-cell-based immunotherapy in multiple sclerosis: induction of regulatory immune networks by T-cell vaccination

Multiple sclerosis (MS) is a chronic inflammatory disease of the CNS with presumed autoimmune origin. Pathogenic autoimmune responses in MS are thought to be the result of a breakdown of self tolerance. Several mechanisms account for the natural state of immunological tolerance to self antigens, including clonal deletion of self-reactive T cells in the thymus. However, autoimmune T cells are also part of the normal T-cell repertoire, supporting the existence of peripheral regulatory mechanisms that keep these potentially pathogenic T cells under control. One such mechanism involves active suppression by regulatory T cells. It has been indicated that regulatory T cells do not function properly in autoimmune disease. Immunization with attenuated autoreactive T cells, T-cell vaccination, may enhance or restore the regulatory immune networks to specifically suppress autoreactive T cells, as shown in experimental autoimmune encephalomyelitis, an animal model for MS. In the past decade, T-cell vaccination has been tested for MS in several clinical trials. This review summarizes these clinical trials and updates our current knowledge on the induction of regulatory immune networks by T cell vaccination.

T cell recognition of self-antigen presenting cells by protein transfer assay reveals a high frequency of anti-myelin T cells in multiple sclerosis

Although peripheral blood myelin-autoreactive T cells are thought to play a key role in multiple sclerosis, they are generally considered to have qualitative differences rather than quantitative ones when compared to those found in healthy individuals. Here, we revisited the assessment of myelin-autoreactive T cells in a new approach based on their combined ability to acquire membrane proteins from autologous antigen presenting cells, and to respond to whole myelin extract as the stimulating autoantigen. Using this approach, the myelin-autoreactive T cell frequency in patients with multiple sclerosis was found to be unexpectedly high (n = 22, subtracted values median 2.08%, range 0-6%; background median 1%, range 0-4%) and to exceed that of age/gender-matched healthy individuals significantly (n = 18, subtracted values median 0.1%, range 0-5.3%, P < 0.0001; background median 1.45%, range 0.1-4%). Higher anti-myelin autoreactivity was stable in patients with multiple sclerosis after several months. These data correlated with whole myelin-induced gamma interferon-enzyme-linked immunosorbent spot assay performed under the same conditions, although the values obtained with enzyme-linked immunosorbent spot assay under all conditions were 58 times lower than with this new method. The myelin-autoreactive T cells were memory T cells expressing CD40L with a CD62(low) phenotype, suggesting their ability for homing to tissues. Collectively, these new data show a higher frequency of autoreactive T cells during multiple sclerosis than in age/gender-matched healthy individuals, and support an autoimmune aetiology in multiple sclerosis.

HIV Coreceptors and Their Roles in Leukocyte Trafficking During Neuroinflammatory Diseases

Due to the increasing resistance of HIV-1 to antiretroviral therapies, there has been much emphasis on the discovery and development of alternative therapeutics for HIV-1-infected individuals. The chemokine receptors CXCR4 (Bleul et al. 1996a; Feng et al. 1996; Nagasawa et al. 1996; Oberlin et al. 1996) and CCR5 (Alkhatib et al. 1996; Deng et al. 1996; Dragic et al. 1996) were identified as target molecules from the time their role as coreceptors for HIV-1 entry into leukocytes was first discovered 10 years ago. Initial studies focused on the use of the chemokine ligands, or altered derivatives, of CXCR4 and CCR5 to prevent the entrance of HIV-1 into immune cells (Schols 2006). While these studies showed some initial promise, there was evidence of significant caveats to their use, including selection of alternative coreceptor utilizing strains (Marechal et al. 1999; Mosier et al. 1999) and the potential to cause inflammatory side effects. These data prompted the development and study of small molecule inhibitors of CXCR4 and CCR5, which have also been used to examine the roles of these molecules in a variety of inflammatory and infectious diseases.

Lipid autoreactivity in multiple sclerosis

Lipids comprise over 70% of the myelin sheath but have been largely underinvestigated as autoantigens in multiple sclerosis (MS). This paper cites evidence for the involvement of lipid autoreactivity in MS and details how self lipid cross-reactivity may also contribute to the development of type 1 diabetes and autoimmune thyroid disorders (both of which have been associated with MS). A further analysis of myelin chemistry suggests several mechanisms by which infection may contribute to etiology and trigger lipid autoreactivity via molecular mimicry. This analysis may aid the development of new therapies for autoimmune diseases.

Leukemia inhibitory factor induces an antiapoptotic response in oligodendrocytes through Akt-phosphorylation and up-regulation of 14-3-3

Leukemia inhibitory factor (LIF) promotes the survival of oligodendrocytes (OLG) both in vitro and in an animal model of multiple sclerosis. Here, we show that LIF protects mature rat OLG cultures selectively against the combined insult of the proinflammatory cytokines interferon-gamma and tumor necrosis factor-alpha, but it does not protect against oxidative stress nor against staurosporine induced apoptosis. We further demonstrate that LIF activates the janus kinase (JAK)/signal transducer and activator of transcription 3 (STAT3) and the phosphatidylinositol 3 kinase/Akt pathway in mature OLG. We show that LIF protection is independent of suppressors of cytokine signaling and Bcl-2 mRNA expression levels. To gain further insight into the protective mechanism, a quantitative proteomic approach (DIGE) was applied to identify differentially expressed proteins in LIF-treated OLG. Our results indicate that LIF induces a shift in the cellular machinery toward a prosurvival execution program, illustrated by an enhanced expression of isoforms of the antiapoptotic molecule 14-3-3. These data provide further insight into the mechanisms of LIF-mediated protection of mature OLGs.

Correlation of blood T cell and antibody reactivity to myelin proteins with HLA type and lesion localization in multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the CNS. The numbers of autoimmune T cells and Abs specific for proteins of CNS myelin are increased in the blood in some patients with MS. The aim of this study was to investigate whether there are correlations between the specificity of the autoimmune responses in the blood, the HLA molecules carried by the patient, and the clinical features of MS, because studies on experimental autoimmune encephalomyelitis, an animal model of MS, indicate that autoimmune responses targeting particular myelin proteins and the genetic background of the animal play a role in determining the pattern of lesion distribution. We tested blood T cell immunoreactivity to myelin proteins in 100 MS patients, 70 healthy controls, and 48 patients with other neurological disorders. Forty MS patients had strongly increased T cell reactivity to one or more myelin Ags. In these 40 patients, the most robust correlation was between CD4(+) T cell reactivity to myelin proteolipid protein residues 184-209 (PLP(184-209)) and development of lesions in the brainstem and cerebellum. Furthermore, carriage of HLA-DR4, -DR7, or -DR13 molecules by MS patients correlated with increased blood T cell immunoreactivity to PLP(184-209), as well as the development of lesions in the brainstem and cerebellum. Levels of PLP(190-209)-specific Abs in the blood also correlated with the presence of cerebellar lesions. These findings show that circulating T cells and Abs reactive against specific myelin Ags can correlate with lesion distribution in MS and suggest that they are of pathogenic relevance.

CB2 cannabinoid receptors as an emerging target for demyelinating diseases: from neuroimmune interactions to cell replacement strategies

Amongst the various demyelinating diseases that affect the central nervous system, those induced by an inflammatory response stand out because of their epidemiological relevance. The best known inflammatory-induced demyelinating disease is multiple sclerosis, but the immune response is a common pathogenic mechanism in many other less common pathologies (e.g., acute disseminated encephalomyelitis and acute necrotizing haemorrhagic encephalomyelitis). In all such cases, modulation of the immune response seems to be a logical therapeutic approach. Cannabinoids are well known immunomodulatory molecules that act through CB1 and CB2 receptors. While activation of CB1 receptors has a psychotropic effect, activation of CB2 receptors alone does not. Therefore, to bypass the ethical problems that could result from the treatment of inflammation with psychotropic molecules, considerable effort is being made to study the potential therapeutic value of activating CB2 receptors. In this review we examine the current knowledge and understanding of the utility of cannabinoids as therapeutic molecules for inflammatory-mediated demyelinating pathologies. Moreover, we discuss how CB2 receptor activation is related to the modulation of immunopathogenic states.

Cross-reactivity between peptide mimics of the immunodominant myelin proteolipid protein epitope PLP139-151: comparison of peptide priming in CFA vs. viral delivery

Epidemiological evidence suggests that pathogens may trigger the development of autoimmune diseases such as multiple sclerosis (MS). Pathogens may trigger disease via molecular mimicry, wherein T cells generated against foreign epitopes are also cross-reactive with self-epitopes. Five pathogen-derived molecular mimics of PLP(139-151) (the immunodominant CD4(+) T cell myelin epitope in SJL mice) were previously identified. This study examines the degree of cross-reactivity between the different mimics, comparing mice primed with mimic peptide in CFA with mice infected with recombinant mimic-expressing viruses. The pattern of in vitro reactivity and ability to induce CNS disease differs between peptide priming and virus infection.

Diversified serum IgG response involving non-myelin CNS proteins during experimental autoimmune encephalomyelitis

We sequentially analyzed the serum IgG response against normal mouse brain during experimental autoimmune encephalomyelitis in SJL/J mice injected with CFA, Bordetella pertussis toxin (BPT) and proteolipid protein 139-151 peptide, compared with mice that received CFA and BPT or were uninjected. Dynamic changes were observed from day 0 to day 28 in the 3 groups. Six highly discriminant antigenic bands (kappa=0.974) were identified. Three non-myelin proteins were characterized (mitochondrial aconitase hydratase 2, phosphoglycerate mutase 1, brain specific pyruvate deshydrogenase). The IgG response against two of them was less frequent in EAE whereas it was associated with multiple sclerosis in our previous work.

5HT4 agonists inhibit interferon-γ-induced MHC class II and B7 costimulatory molecules expression on cultured astrocytes

A failure of tight control of MHC class II expression on astrocytes may play a role in the development of autoimmune responses in multiple sclerosis. The 5-HT(4) serotonin receptor agonists cisapride and prucalopride, at concentrations between 10(-10) M and 10(-8) M, reduced interferon-gamma-induced MHC class II immunostaining in cultured astrocytes derived from newborn Wistar rats by approximately 50-60%. The magnitude of MHC class II inhibition by 5-HT(4) agonists was comparable to that of interferon-beta. The alpha(1)-adrenergic receptor agonist phenylephrine was without effect. Cisapride (10(-9) M) also prevented interferon-gamma-induced B7-1 and B7-2 immunostaining. Our results suggest that 5-HT(4) agonists may have therapeutic potential in multiple sclerosis by inhibiting the up-regulation of immune responsiveness of astrocytes in the central nervous system.

Leukemia inhibitory factor is produced by myelin-reactive T cells from multiple sclerosis patients and protects against tumor necrosis factor-α-induced oligodendrocyte apoptosis

In multiple sclerosis (MS), damage to oligodendrocytes is believed to be caused by an aberrant immune response initiated by autoreactive T cells. Increasing evidence indicates that these T cells are not exclusively detrimental but might also exert protective effects. We report for the first time that myelin-reactive T-cell clones from eight MS patients (6/19) and five healthy controls (4/11) produce leukemia inhibitory factor (LIF), a member of the neuropoietic family of neurotrophins. In addition, T-cell clones specific for tetanus toxoid, CD4(+) and CD8(+) T cells, and monocytes, but not B cells, secreted LIF. LIF-producing T lymphocytes and macrophages were also identified immunohistochemically in both active and chronic-active MS lesions. We further demonstrated dose-dependent protective effects of LIF on tumor necrosis factor-alpha-induced apoptosis of oligodendrocytes. In conclusion, our data demonstrate that peripheral and CNS-infiltrating T cells from MS patients produce LIF, a protective factor for oligodendrocytes. This study emphasizes that secretion of LIF may contribute to the neuroprotective effects of autoreactive T cells.

Downregulation of VLA-4 on T cells as a marker of long term treatment response to interferon beta-1a in MS

We determined longitudinally the expression of a panel of adhesion molecules on T cells and soluble ICAM-1, VCAM-1 and tumor necrosis factor apoptosis inducing ligand (TRAIL) in serum during first year of the PRISMS Study with IFNbeta1a in MS. Clinical data and quantitative MRI data were available for 4 years. VLA-4 was down-regulated on T cells and VCAM-1 was up-regulated in serum during the first 3 to 6 months of therapy in patients with favorable long-term treatment response (EDSS progression </=1.0 in 4 years). Short disease duration and low EDSS were clinical pre-treatment characteristics related to good long-term response to therapy.

Longitudinal single-cell cytokine responses reveal recurrent autoimmune myelin reactivity in relapsing--remitting multiple sclerosis patients

The relationship between multiple sclerosis (MS) disease activity and myelin protein-induced cytokine responses over time is not elucidated. We addressed this relationship by examining longitudinal cytokine responses to myelin proteins every three months for one year, in the context of gadolinium (gad)-enhancing brain lesions and of clinical relapses. The ELISPOT assay was used to determine the ex vivo cytokine production in response to nine amino acid long peptides spanning the entire proteolipid protein (PLP) and myelin basic protein (MBP) molecules in relapsing-remitting (RR) MS patients and matched healthy controls. We identified three longitudinal levels of myelin-induced cytokine secretion by adding up the positive responses for all PLP or MBP peptides obtained for five timepoints, at three-month intervals: low reactivity (< 200 cumulative cytokine-secreting cells), isolated peptide reactivity (201-450 cumulative cytokine-secreting cells) and recurrent protein-wide bursts of cytokine reactivity (> 451 cumulative cytokine-secreting cells). The majority of MS patients showed recurrent bursts to PLP and MBP. In contrast, controls showed a more even distribution between all levels of cytokine reactivity. The majority of patients with gad-enhancing lesions showed PLP/IFN gamma and MBP/IFN gamma recurrent burst responses. This is the first longitudinal study on MS patients in which nine amino acid long myelin peptides are used to reveal the broad range of PLP- and MBP-peptide cytokine reactivity across the whole molecule of these two major myelin proteins. This study also reveals the extremely dynamic nature of the immune reactivity to numerous regions of myelin, which can fluctuate dramatically over time. Such fluctuation could hamper the efficacy of antigen-based therapies for MS.

Spread of T lymphocyte immune responses to myelin epitopes with duration of multiple sclerosis

Although the primary cause of multiple sclerosis (MS) is unclear, evidence supports a role for autoimmune attack of myelin by T lymphocytes. However, it has been difficult to relate patterns of autoimmunity to pathogenesis. In mouse models, the case has been made for relapsing and remitting disease driven by epitope spread: an initial lesion leads to presentation of central nervous system antigens, in turn triggering the next wave of autoimmune T cells of different specificity, the response thus broadening. Few studies have been done to determine whether these events could be important over the longer time scale of human disease. We compared T cell responses with a panel of myelin epitopes in clinically isolated syndrome patients with a first attack, patients with MS with a mean disease duration of 0.95 years, and patients with MS having a mean disease duration of 15.9 years. T cells from patients with long-term disease recognize more myelin epitopes than patients with recent-onset disease. The epitope myelin basic protein 131-149, in particular, was more commonly recognized by patients with long-term disease. The data support the notion that the T cell response in MS broadens with time and is thus implicated in the ongoing pathogenic process. However, there was no clear correlation between disease severity and number of epitopes recognized. This may argue against a simple causal role of epitope spread in driving progression, as has been suggested in experimental allergic encephalomyelitis.

Astrocytic beta2-adrenergic receptors and multiple sclerosis

Despite intensive research, the cause and a cure of multiple sclerosis (MS) have remained elusive and many aspects of the pathogenesis are not understood. Immunohistochemical experiments have shown that astrocytic beta(2)-adrenergic receptors are lost in MS. Because norepinephrine mediates important supportive and protective actions of astrocytes via activation of these beta(2)-adrenergic receptors, we postulate that this abnormality may play a prominent role in the pathogenesis of MS. First, it may allow astrocytes to act as facultative antigen-presenting cells, thereby initiating T-cell mediated inflammatory responses that lead to the characteristic demyelinated lesions. Second, it may contribute to inflammatory injury by stimulating the production of nitric oxide and proinflammatory cytokines, and reducing glutamate uptake. Third, it may lead to apoptosis of oligodendrocytes by reducing the astrocytic production of trophic factors, including neuregulin, nerve growth factor and brain-derived neurotrophic factor. Fourth, it may impair astrocytic glycogenolysis, which supplies energy to axons, and this may represent a mechanism underlying axonal degeneration that is hold responsible for the progressive chronic disability.

T-cell vaccination in multiple sclerosis: update on clinical application and mode of action

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS). Autoreactive T cells specific for myelin antigens are considered to play a prominent role in the initiation of the local inflammatory response, ultimately leading to myelin damage. Several studies indicate that autoreactive T cells are not completely deleted in the thymus, but are part of the normal T cell repertoire. Accidentally activated autoreactive T cells, however, may not automatically lead to autoimmune disease. Several reports support the existence of peripheral regulatory networks that prevent the activation and expansion of pathogenic T cells. Anti-idiotypic and anti-ergotypic T cells are part of this regulatory network and are thought to control autoreactive T cells by recognition of certain clonotypic and ergotypic determinants. These clonotypic networks may not function properly in patients with MS. Immunization with attenuated autoreactive T cells, termed T cell vaccination (TCV), may enhance or restore the regulatory networks to specifically suppress the autoreactive T cells as shown in experimental autoimmune encephalomyelitis (EAE), a commonly used animal model for MS. In the past decade, TCV has been tested for MS in several clinical trails. This review summarizes these clinical trails and updates our current knowledge on the mode of action of T cell vaccination.

Beta 2-adrenoceptor involvement in inflammatory demyelination and axonal degeneration in multiple sclerosis

Relapses of multiple sclerosis (MS) are considered to be the clinical expression of acute T-cell-mediated inflammatory demyelinating lesions disseminated in the CNS, whereas disease progression seems to result from widespread axonal degeneration. The pathophysiology of both disease components is incompletely understood. Astrocytes in MS lack beta(2)-adrenoceptors, which via cAMP-mediated processes inhibit the expression of major histocompatibility (MHC) class II molecules and stimulate glycogenolysis in normal conditions. In a pro-inflammatory CNS environment this beta(2)-adrenoceptor defect might allow astrocytes to transform into facultative antigen-presenting cells that can initiate the inflammatory cascade. The same receptor defect might impair astrocytic glycogenolysis, which normally generates lactate that is transported to axons as an energy source. Failure of axonal energy metabolism might result in axonal degeneration through mechanisms that involve intra-axonal accumulation of Ca(2+) ions and mitochondrial dysfunction. If this hypothesis is correct, therapies designed to elevate cAMP levels in astrocytes should reduce or prevent both relapses and progression of MS.

Multiple sclerosis: a study of chemokine receptors and regulatory T cells in relation to MRI variables

Magnetic resonance imaging (MRI) remains the most valuable tool for monitoring disease activity and progression in patients with multiple sclerosis (MS), a chronic demyelinating disease of the central nervous system (CNS) with presumably autoimmune etiology. Chemokine receptors have been implicated in MS as key molecules directing inflammatory cells into the CNS. Regulatory (CD4+CD25+) T cells (Tr cells) are important in suppressing autoimmunity, and their absolute or functional deficit could be expected in MS. In the present study, venous blood was obtained from MS patients concurrent with MRI examination of the brain, and expression of chemokine receptors CCR1, CCR2, CCR5, CXCR3 and CXCR4 by CD4 T cells and monocytes, proportions of Tr cells, as well as expression of CD45RO, CD95, CTLA-4, HLA-DR and interleukin (IL)-10 by Tr cells and non-Tr (CD25-) CD4 T cells was analyzed by flow cytometry. Surface expression of CXCR3 by CD4 T cells was downregulated in the group of patients with high lesion load (LL) on T2-weighted images and gadolinium (Gd)-enhancing lesions on T1-weighted images, compared to the group with high LL and no Gd-enhancing lesions, and to the group with low LL, suggesting internalization of CXCR3 due to the release of its chemokine ligand (IP-10/CXCL10) from active MS lesions. Proportions of Tr cells amongst all CD4 T cells, and expression of IL-10 by Tr cells were increased in the patients with high LL and Gd-enhancing lesions. These results suggest that there is correlation between MRI parameters, chemokine receptor expression and the status of circulating Tr cells in MS, but further studies need to discriminate between pathogenetically relevant and bystander phenomena.

Interferon gamma responses to myelin peptides in multiple sclerosis correlate with a new clinical measure of disease progression

The relationship between autoreactivity to myelin antigens and disease progression in multiple sclerosis (MS) is not fully understood. We addressed this relationship by cross-sectionally comparing an objective measure of MS disability with immune cytokine responses to myelin proteins. The ELISPOT assay was used to determine the ex vivo interferon gamma (IFNgamma) and interleukin-10 (IL-10) production by peripheral blood mononuclear cells (PBMCs) in response to peptides spanning the entire proteolipid protein (PLP) and myelin basic protein (MBP) molecules in 20 patients with relapsing-remitting (RR) MS and 27 age- and sex-matched healthy controls. MS patients showed significantly higher MBP-induced IFNgamma responses and PLP-induced IL-10 responses compared with healthy controls. Using the Multiple Sclerosis Functional Composite (MSFC), a new multifactorial measure of disability, MS patients showed a significant correlation between the IFNgamma response to PLP peptides and MBP peptides, and disability. In contrast, in MS patients, there was no correlation between the MSFC and the response to unrelated control antigens or mitogens. These data show that myelin-specific T lymphocytes secreting the inflammatory cytokine IFNgamma correlate with functional impairment in MS, supporting an antigen-specific link between the immune response to myelin and disability in MS.

Immunological questions on hematopoietic stem cell transplantation for multiple sclerosis

Multiple sclerosis (MS) is considered an inflammatory autoimmune disorder. Approved immunotherapies are only moderately effective in reducing disease exacerbations and brain inflammation in a subset of patients. Autologous hematopoietic stem cell transplantation (HSCT) has emerged in recent years as the first opportunity to offer to patients a radical, potentially curative treatment. Here, we will summarize key immunopathological aspects of MS and discuss important questions that need to be addressed to clarify the therapeutic role and mechanism of action of HSCT in this disorder.

Reactive astrocytes in chronic active lesions of multiple sclerosis express co-stimulatory molecules B7-1 and B7-2

Astrocytes in active lesions of multiple sclerosis (MS) express major histocompatibility (MHC) class II molecules, and may play an important role in the presentation of antigen to myelin-specific T cells.However, it has been postulated that astrocytes are unable to act as antigen-presenting cells (APCs) because they would lack the B7 co-stimulatory molecules to activate these T cells. By using double labeling immunofluorescence staining, we demonstrate that reactive astrocytes in chronic active plaques of multiple sclerosis express the co-stimulatory molecules B7-1 and B7-2, and hence have the necessary attributes to act as antigen-presenting cells.

T cell vaccination in multiple sclerosis patients with autologous CSF-derived activated T cells: results from a pilot study

Myelin-reactive T cells are considered to play an essential role in the pathogenesis of multiple sclerosis (MS), an autoimmune disease of the central nervous system. We have previously studied the effects of T cell vaccination (TCV), a procedure by which MS patients are immunized with attenuated autologous myelin basic protein (MBP)-reactive T cell clones. Because several myelin antigens are described as potential autoantigens for MS, T cell vaccines incorporating a broad panel of antimyelin reactivities may have therapeutic effects. Previous reports have shown an accumulation of activated T cells recognizing multiple myelin antigens in the cerebrospinal fluid (CSF) of MS patients. We conducted a pilot clinical trial of TCV with activated CD4+ T cells derived from CSF in five MS patients (four RR, one CP) to study safety, feasibility and immune effects of TCV. CSF lymphocytes were cultured in the presence of rIL-2 and depleted for CD8 cells. After 5-8 weeks CSF T cell lines (TCL) were almost pure TCR alpha beta+CD4+ cells of the Th1/Th0 type. The TCL showed reactivity to MBP, MOG and/or PLP as tested by Elispot and had a restricted clonality. Three immunizations with irradiated CSF vaccines (10 million cells) were administered with an interval of 2 months. The vaccinations were tolerated well and no toxicity or adverse effects were reported. The data from this small open-label study cannot be used to support efficacy. However, all patients remained clinically stable or had reduced EDSS with no relapses during or after the treatment. Proliferative responses against the CSF vaccine were observed in 3/5 patients. Anti-ergotypic responses were observed in all patients. Anti-MBP/PLP/MOG reactivities remained low or were reduced in all patients. Based on these encouraging results, we recently initiated a double-blind placebo-controlled trial with 60 MS patients to study the effects of TCV with CSF-derived vaccines in early RR MS patients.

Skewed autoantibody reactivity to the extracellular domain of myelin oligodendrocyte glycoprotein in multiple sclerosis

Myelin oligodendrocyte glycoprotein (MOG) is found to induce both autoreactive T-cell and antibody responses associated with demyelinating pathology and is implicated in the pathogenesis of multiple sclerosis (MS). In this study, we addressed the potential association of anti-MOG immune responses with MS by examining, comparatively, both the T-cell and antibody responses to recombinant MOG fragments in MS patients and healthy subjects. T cells recognizing MOG were detected in MS patients as well as in healthy subjects, and their precursor frequency in the blood was not increased in patients with MS. MOG-reactive T cells isolated from both MS patients and healthy subjects exhibited a similar cytokine profile, producing interleukin (IL)-4, IL-10 and tumour necrosis factor (TNF), but not interferon-gamma (IFN-gamma), and recognized predominantly the extracellular (residues 1-60) and the transmembrane/cytoplasmic (residues 154-218) domains of MOG. In contrast, anti-MOG antibodies derived from MS patients displayed a skewed reactivity pattern, even though the occurrence and titres of serum anti-MOG antibodies were only slightly elevated in MS patients. MS-derived autoantibodies were predominantly directed at the 1-60 region of MOG, while naturally occurring anti-MOG antibodies derived from healthy individuals reacted selectively to the 154-218 domain. These differences were statistically significant. The findings of this study are consistent with the presence of anti-MOG antibodies within demyelinating lesions of MS and their role in the induction of demyelinating pathology in animal models. The study has important implications in the understanding of the autoimmune processes in MS.