Cytokine profile of myelin basic protein-reactive T cells in multiple sclerosis and healthy individuals

Assessment of commonly used methods to determine myelin-reactivity of T cells in multiple sclerosis

Many studies have analyzed myelin-reactivity of T cells in multiple sclerosis (MS); however, with conflicting results. In this study we compare methods to determine myelin reactivity of T cells and aim to delineate the cause of inconsistency in the literature. Challenging T cells with myelin antigens we found a significant increase in antigen-reactivity of T cells from patients with MS using an ELISpot-assay, in contrast to a CFSE-dilution assay. Comparing the two assays showed that the myelin-reactive T cells detected in the ELISpot-assay originated primarily from effector memory T cells in contrast to the myelin-reactive T cells of the CFSE-assay representing a population of both naïve, central memory and effector memory T cells. This diversity in T cell populations activated in the two assays likely contribute to the discrepancy found in the literature and encourages thorough considerations when choosing an assay to determine antigen-specificity of T cells in future studies.

[Familial multiple sclerosis in Tomsk region]

AIM

Multiple sclerosis (MS) has a multifactorial etiology. To explore a role of genetic factors in the pathogenesis of MS, the authors studied familial cases of MS.

MATERIAL AND METHODS

For an analysis of familial cases, a database of 320 MS patients registered in Tomsk region since 1980 till 2014 was used. The following items for each patient were recorded: disease onset, manifestation of disease, duration of first remission, rate of progression of disease.

RESULTS AND CONCLUSION

Nine families with several members with MS were identified. In 2014, the frequency of familial cases in the MS population of Tomsk region was 4.7%. The prevalence of familial MS was 1.4 cases per 100.000 of people. The younger age at disease onset and higher rate of disease progression measured with the EDSS in parent-child pairs were identified. The most families with several members with MS were characterized by clinical polymorphism of onset, duration and rate of disease progression.

Review : Gene Therapy: Applications to the Neurosciences and to Neurological Disease

Gene expression is involved in some way in every human disease. As our knowledge of gene structure and function has blossomed in the last 2 decades, so too has our potential genetically-based repertoire for combating disease. Gene therapy refers to the manipulation of gene expression, either by augmenting the expression of therapeutic genes or by diminishing the expression of deleterious genes. In some neurological diseases, such as trauma, ischemia, and neurodegenerative disorders, gene therapy might be used to express genes for such substances as growth factors or neurotransmitters to prevent neuronal degeneration or to compensate for lost function, respectively. In other cases, gene therapy could be used to block the expression of genes that cause disease such as β-amyloid precursor protein or the Huntingtin gene. In inherited diseases of the nervous system such as muscular dystrophy, normal gene copies could be placed into the nervous system to compensate for lost function resulting from abnormal gene expression. The tools for achieving well-targeted, sustained, and safe gene delivery in the nervous system are now becoming available, and this technology is likely to substantially alter the nature of neurological therapy in the future. NEUROSCIENTIST 4:398-407, 1998

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.

IL-25 prevents T cell-mediated neurotoxicity by decreasing LFA-1 expression

Autoimmune diseases such as multiple sclerosis (MS) are thought to develop due to a dysregulation in the normal T(H)1-T(H)17/T(H)2 immune system balance, where pro-inflammatory responses with a T(H)1/T(H)17 prevalence develop. Some therapeutic treatments in MS promote a shift toward a TH2-prevalent environment and this has been shown to be protective. However, not all patients respond to current immunomodulatory treatments in MS so that new immunomodulatory drugs that can promote a shift of the immune system into an anti-inflammatory T(H)2 status are needed. IL-25 is a cytokine of the IL-17 family with powerful anti-inflammatory properties. This study demonstrates that IL-25 exerts neuroprotective functions by reducing T cell-mediated killing of human fetal neurons. The mechanism of action of this IL-25-mediated neuroprotective effect appears to be linked to reduction in the expression of the adhesion molecule LFA-1, which is relevant in stabilizing the immune synapse during cytotoxicity.

Interleukin-33 upregulation in peripheral leukocytes and CNS of multiple sclerosis patients

Multiple sclerosis (MS) is an immune-mediated demyelinating disease of the central nervous system (CNS). Here we document for the first time that the cytokine IL-33 is upregulated in both the periphery and the CNS of MS patients. Plasma IL-33 was elevated in MS patients compared to normal subjects and a three-month treatment of MS patients with interferon β-1a resulted in a significant decrease of IL-33 levels. Similarly, stimulated cultured lymphocytes and macrophages from MS patients had elevated IL-33 levels compared to normal subjects. In parallel, the transcription factor NF-κB that mediates IL-33 transcription was also elevated in leukocytes of MS patients. IL-33 was elevated in normal-appearing white matter and plaque areas from MS brains and astrocytes were identified as an important source of IL-33 expression in the CNS. In summary, IL-33 levels are elevated in the periphery and CNS of MS patients, implicating IL-33 in the pathogenesis of MS.

Quantitative differences in the immunomodulatory effects of Rebif and Avonex in IFN-β 1a treated multiple sclerosis patients

Interferon-β (IFN-β) is a current effective treatment for multiple sclerosis (MS) and exerts its therapeutic effects by down-modulating the systemic immune response and cytokine signaling. In clinical practice there are several formulations of interferon including a low dose of IFN-β 1a formulation of 30 μg IM once weekly (Avonex) and a high dose formulation of 44 μg SC three times weekly (Rebif). Recent studies suggest that Rebif is more efficacious compared to Avonex in preventing relapses and decreasing MRI activity in relapsing remitting MS (RRMS) patients. This study examines whether there are quantitative gene expression changes in interferon-treated RRMS patients that can explain the difference in efficacy and side effects between Rebif and Avonex. Herein, RRMS patients were treated for three months with IFN-β 1a and the levels of plasma cytokines and gene expression in peripheral blood mononuclear cells were examined. Thirty-two normal subjects were compared to thirty-two RRMS patients, of which ten were treated with Rebif and ten with Avonex. Rebif and Avonex both significantly and equally suppressed plasma TNF-α and IL-6 levels. Rebif suppressed IL-13 significantly more than Avonex. Rebif also significantly suppressed the levels of the chemokines CCL17 and RANTES, the protease ADAM8, and COX-2 at a higher degree compared to Avonex. The STAT1-inducible genes IP-10 and caspase 1 were significantly increased with Rebif compared to Avonex. In conclusion, the higher dosed, more frequently administered IFN-β 1a Rebif when compared to IFN-β 1a Avonex has more potent immunomodulatory effects. These quantitative results might relate to efficacy and side-effect profile of the two IFN-β 1a formulations and provide prospective practical clinical tools to monitor treatment and adjust dosage.

Regulatory and pro-inflammatory phenotypes of myelin basic protein-autoreactive T cells in multiple sclerosis

MBP-specific autoreactive T cells are considered pro-inflammatory T cells and thought to play an important role in the pathogenesis of multiple sclerosis (MS). Here, we report that MBP(83-99)-specific T cells generated from MS patients (n = 7) were comprised of pro-inflammatory and regulatory subsets of distinct phenotypes. The pro-inflammatory phenotype was characterized by high production of IFN-gamma, IL-6, IL-21 and IL-17 and low expression of FOXP3, whereas the regulatory subset expressed high levels of FOXP3 and exhibited potent regulatory functions. The regulatory subset of MBP-specific T cells appeared to expand from the CD4(+)CD25(-) T-cell pool. Their FOXP3 expression was stable, independent of the activation state and it correlated with suppressive function and inversely with the production of IFN-gamma, IL-6, IL-21 and IL-17. In contrast, the phenotype and function of FOXP3(low) MBP-specific T cells were adaptive and dependent on IL-6. The higher frequency of FOXP3(high) MBP-specific T cells was observed when IL-6 was neutralized in the culture of PBMC with MBP. The study provides new evidence that MBP-specific T cells are susceptible to pro-inflammatory cytokine milieu and act as either pro-inflammatory or regulatory T cells.

Macrophages of multiple sclerosis patients display deficient SHP-1 expression and enhanced inflammatory phenotype

Recent studies in mice have demonstrated that the protein tyrosine phosphatase SHP-1 is a crucial negative regulator of proinflammatory cytokine signaling, TLR signaling, and inflammatory gene expression. Furthermore, mice genetically lacking SHP-1 (me/me) display a profound susceptibility to inflammatory CNS demyelination relative to wild-type mice. In particular, SHP-1 deficiency may act predominantly in inflammatory macrophages to increase CNS demyelination as SHP-1-deficient macrophages display coexpression of inflammatory effector molecules and increased demyelinating activity in me/me mice. Recently, we reported that PBMCs of multiple sclerosis (MS) patients have a deficiency in SHP-1 expression relative to normal control subjects indicating that SHP-1 deficiency may play a similar role in MS as to that seen in mice. Therefore, it became essential to examine the specific expression and function of SHP-1 in macrophages from MS patients. Herein, we document that macrophages of MS patients have deficient SHP-1 protein and mRNA expression relative to those of normal control subjects. To examine functional consequences of the lower SHP-1, the activation of STAT6, STAT1, and NF-kappaB was quantified and macrophages of MS patients showed increased activation of these transcription factors. In accordance with this observation, several STAT6-, STAT1-, and NF-kappaB-responsive genes that mediate inflammatory demyelination were increased in macrophages of MS patients following cytokine and TLR agonist stimulation. Supporting a direct role of SHP-1 deficiency in altered macrophage function, experimental depletion of SHP-1 in normal subject macrophages resulted in an increased STAT/NF-kappaB activation and increased inflammatory gene expression to levels seen in macrophages of MS patients. In conclusion, macrophages of MS patients display a deficiency of SHP-1 expression, heightened activation of STAT6, STAT1, and NF-kappaB and a corresponding inflammatory profile that may be important in controlling macrophage-mediated demyelination in MS.

Interferon-beta treatment in multiple sclerosis attenuates inflammatory gene expression through inducible activity of the phosphatase SHP-1

Interferon-beta is a current treatment for multiple sclerosis (MS). Interferon-beta is thought to exert its therapeutic effects on MS by down-modulating the immune response by multiple potential pathways. Here, we document that treatment of MS patients with interferon beta-1a (Rebif) results in a significant increase in the levels and function of the protein tyrosine phosphatase SHP-1 in PBMCs. SHP-1 is a crucial negative regulator of cytokine signaling, inflammatory gene expression, and CNS demyelination as evidenced in mice deficient in SHP-1. In order to examine the functional significance of SHP-1 induction in MS PBMCs, we analyzed the activity of proinflammatory signaling molecules STAT1, STAT6, and NF-kappaB, which are known SHP-1 targets. Interferon-beta treatment in vivo resulted in decreased NF-kappaB and STAT6 activation and increased STAT1 activation. Further analysis in vitro showed that cultured PBMCs of MS patients and normal subjects had a significant SHP-1 induction following interferon-beta treatment that correlated with decreased NF-kappaB and STAT6 activation. Most importantly, experimental depletion of SHP-1 in cultured PBMCs abolished the anti-inflammatory effects of interferon-beta treatment, indicating that SHP-1 is a predominant mediator of interferon-beta activity. In conclusion, interferon-beta treatment upregulates SHP-1 expression resulting in decreased transcription factor activation and inflammatory gene expression important in MS pathogenesis.

Interleukin-1beta: a bridge between inflammation and excitotoxicity?

Interleukin-1 (IL-1) is a proinflammatory cytokine released by many cell types that acts in both an autocrine and/or paracrine fashion. While IL-1 is best described as an important mediator of the peripheral immune response during infection and inflammation, increasing evidence implicates IL-1 signaling in the pathogenesis of several neurological disorders. The biochemical pathway(s) by which this cytokine contributes to brain injury remain(s) largely unidentified. Herein, we review the evidence that demonstrates the contribution of IL-1beta to the pathogenesis of both acute and chronic neurological disorders. Further, we highlight data that leads us to propose IL-1beta as the missing mechanistic link between a potential beneficial inflammatory response and detrimental glutamate excitotoxicity.

A CFSE based assay for measuring CD4+CD25+ regulatory T cell mediated suppression of auto-antigen specific and polyclonal T cell responses

CD4(+)CD25(+) regulatory T cells (Tregs) are considered to play a key role as suppressors of immune mediated reactions. The analysis of Treg function in patients with autoimmune, allergic or oncogenic diseases has emerged over the past years. In the present study we describe a CFSE based protocol to measure Treg mediated suppression of CD4(+) T cells. Measuring Treg suppressive capacity towards proliferation of anti-CD3 Ab stimulated CD4(+)CD25(-) T cells in coculture experiments by means of a CFSE based and a classical [(3)H]thymidine incorporation assay gave similar results, provided that CD4(+)CD25(+) T cells were anergic. However, when CD4(+)CD25(+) T cells proliferated upon mitogenic stimulation, data obtained by the CFSE assay allowed the detection of a significant Treg suppression whereas this was clearly underestimated using the [(3)H]thymidine assay. In addition, an indirect CFSE based method was developed to analyze antigen specific responses of total CD4(+) T cells and Treg depleted CD4(+) T cells (i.e. CD4(+)CD25(-) T cells). Our results indicate that, in healthy individuals, CD4(+) T cell responses against the multiple sclerosis (MS) auto-antigens, myelin basic protein (MBP) and myelin oligodendrocyte glycoprotein (MOG), were increased in Treg depleted CD4(+) T cells as compared to total CD4(+) T cells. Our initial data suggest that Tregs in MS patients show an impaired suppression of myelin reactive T cells when compared to healthy controls. Moreover, this experimental setup permits the measurement of cytokine production of the antigen proliferated CFSE(low) T cells by additional flow cytometric analyses. In conclusion, the described CFSE based Treg suppression assay is a valuable tool to study suppressor T cells in (auto)immune disorders.

Effects of IFN-beta, leptin and simvastatin on LIF secretion by T lymphocytes of MS patients and healthy controls

In multiple sclerosis (MS), oligodendrocyte injury is believed to be caused by an aberrant immune response initiated by autoreactive T cells. Increasing evidence indicates that inflammatory responses in the central nervous system are not exclusively detrimental, but may also exert protective effects. Such protective effects are potentially mediated by the local secretion of neurotrophic factors by immune cells. We previously reported that T cells and monocytes in vitro and in inflammatory MS lesions produce leukaemia inhibitory factor (LIF), a member of the neuropoietic family of neurotrophins. In the present study, we report a reduced LIF production by CD4+ T cells of relapsing remitting MS patients as compared to healthy controls. Furthermore, immunomodulatory agents such as leptin, IFN-beta and simvastatin were studied for their potential to alter LIF and secretion of other cytokines by T cells and monocytes of relapsing remitting MS patients and healthy controls. Low doses of simvastatin, but not IFN-beta or leptin enhanced LIF secretion by CD4+ T cells of RR-MS patients. We further demonstrated that LIF did not influence viability, proliferation and cytokine secretion of T cells. Together these data provide new information on the regulation of LIF secretion by immune cells. Further insights into the complex regulation of neurotrophic factors such as LIF may prove useful for treatment of MS.

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.

Differential Activation of ERK, p38, and JNK Required for Th1 and Th2 Deviation in Myelin-Reactive T Cells Induced by Altered Peptide Ligand

Autoreactive T cells can be induced by altered peptide ligands to switch Th1 and Th2 phenotypes. The underlying molecular mechanism is critical for understanding of activation of autoreactive T cells and development of novel therapeutic strategies for autoimmune conditions. In this study, we demonstrated that analog peptides of an immunodominant epitope of myelin basic protein (residues 83-99) with alanine substitution at Val(86) and His(88) had a unique partial agonistic property in the induction of Th1 or Th2 deviation in MBP(83-99)-reactive T cell clones typical of Th0 phenotype. The observed phenotypic switch involved differential activation of ERK, p38, and JNK MAPKs. More specifically, Th1 deviation induced by peptide 86V-->A (86A) correlated with enhanced p38 and JNK activities, while Th2 deviation by peptide 88H-->A (88A) was associated with up-regulated ERK activity and a basal level of p38 and JNK activity. Further characterization revealed that a specific inhibitor for ERK selectively prevented Th2 deviation of MBP(83-99)-specific T cells. Conversely, specific inhibitors for p38 and JNK blocked Th1 deviation in the same T cell preparations induced by peptide 86A. The findings have important implications in our understanding of regulation of ERK, p38, and JNK by altered peptide ligands and their role in cytokine regulation and phenotype switch of autoreactive T cells.

Effects of TNF-alpha and IFN-gamma on nitric oxide-induced neurotoxicity in the mouse brain

The present study investigated the interaction between highly reactive gaseous-free radical NO and cytokines that are produced by activated Th-1 cells on the cerebral immune response and neuronal integrity. CD-1 mice received an intrastriatal infusion of different solutions containing the NO synthase inhibitor N(G)-nitro-L-arginine methylester, NO-releasing substance sodium nitroprusside (SNP), IFN-gamma, and/or TNF-alpha. The solution containing both cytokines caused a profound and transient transcriptional activation of numerous genes encoding proinflammatory proteins in microglial/monocytic cells ipsilateral to infusion site. This increase in gene expression peaked 1 day after the cerebral bolus of cytokines and returned to basal levels from 3 to 7 days post administration. N(G)-nitro-L-arginine methylester further stimulated this immune reaction to IFN-gamma and TNF-alpha, but the brain of these mice failed to exhibit signs of neurodegeneration and demyelination. In contrast, a single bolus of SNP in the striatal region caused neuronal death and demyelination as early as 1 to 3 days following the infusion with the NO donor. This phenomenon was greatly exacerbated by the coadministration of both cytokines, although TNF-alpha remained the most critical cytokine to enhance the damage of cerebral elements. These data provide evidence that NO has the ability to modulate the immune response, which is not by itself detrimental for the brain. However, SNP-induced NO production together with TNF-alpha in the cerebral environment are critical events leading to intense neurodegeneration and demyelination in vivo.

Cytokine-induced cell death in human oligodendroglial cell lines: I. Synergistic effects of IFN-gamma and TNF-alpha on apoptosis

Multiple sclerosis is a chronic inflammatory disease of the central nervous system. Myelin and oligodendrocytes are considered the major targets of injury caused by a cell-mediated immune response. There is circumstantial evidence that proinflammatory cytokines like tumor necrosis factor alpha (TNF-alpha) and interferon gamma (IFN-gamma) could have disease-promoting roles in multiple sclerosis (MS). In the present study, the cytotoxic effects of IFN-gamma and TNF-alpha on the human oligodendroglial cell lines human oligodendroglioma (HOG) and MO3.13 were analyzed. When the oligodendroglial cell lines were cultured in the presence of IFN-gamma or TNF-alpha, apoptotic cell death was observed in both cell lines after >24 hr incubation. Apoptosis was evidenced by a decrease in cell viability, apoptotic changes in cell and nucleus morphology, and disruption of the membrane asymmetry. Our data show that TNF-alpha and IFN-gamma induce apoptosis in a dose-dependent fashion in both oligodendroglial cell lines and that their synergistic effect results in enhanced cell death. Understanding the regulation of cell death pathways in oligodendrocytes is critical for protecting myelin-producing cells and their associated axons during injury in patients with MS.

Antibodies to myelin basic protein, myelin oligodendrocytes peptides, alpha-beta-crystallin, lymphocyte activation and cytokine production in patients with multiple sclerosis

OBJECTIVE

To measure neurone-specific humoral and cellular immune parameters in MRI-positive patients with multiple sclerosis (MS).

BACKGROUND

It has been postulated from animal models for MS and in situ evidence in MS patients that antibodies, activated T cells and proinflammatory cytokines are involved in the destruction of myelin sheaths and loss of oligodendrocytes in active areas.

SUBJECTS AND METHODS

Blood samples were obtained from 20 healthy control subjects and 20 patients with abnormal MRI and clinical diagnosis of MS. Sera were tested for levels of IgG, IgM and IgA against myelin basic protein (MBP), myelin oligodendrocyte glycoprotein (MOG) peptides, and a small heat-shock protein, alpha-beta-crystallin. Lymphocytes were isolated and cultured in the presence or absence of MBP, MOG peptides and alpha-beta-crystallin, measured for stimulated T cells, cytokine production and compared with controls.

RESULTS

Patients with MS showed the highest levels of IgG, IgM or IgA antibodies against one or all three tested antigens. Moreover, in the presence of MBP, MOG peptides or alpha-beta-crystallin, a significant percent- age of lymphocytes from MS patients underwent blast transformation, which resulted in high levels of interferon gamma (IFN-gamma), tumour necrosis factor alpha (TNF-alpha) and tumour necrosis factor beta (TNF-beta) production. Sensitivity of these assays was 60-80% and specificity, 65-70%.

CONCLUSIONS

Detection of antibodies against MBP, MOG peptides, alpha-beta-crystallin, lymphocyte stimulation and production of proinflammatory cytokines in response to these antigens could be used as surrogate markers for the confirmation of MS diagnosis. A combination of antibodies, lymphocyte activation or cytokine production with abnormal MRI may significantly increase the sensitivity and specificity of MS diagnosis.

Alpha B-crystallin is not a dominant peripheral T-cell autoantigen in multiple sclerosis amongst Sardinians

The heat shock protein alpha B-crystallin appears to be the dominantly recognized autoantigen in the early demyelinative process of multiple sclerosis (MS) in brain of patients. In Sardinia, MS is linked to human leucocyte antigen (HLA)-DR alleles that might influence the production of cytokines from peripheral lymphocytes. We tested the nature of peripheral anti-alpha B-crystallin-specific T-cell response in the context of predisposing HLA haplotypes both in MS patients and healthy controls. The alpha B-crystallin specific T-cell lines were generated by using the 'split-well' technique. The results indicate that the presence of short-term T-cell lines towards alpha B-crystallin is numerically comparable between the two groups and not restricted to MS-predisposing HLA-DR alleles. As for the T-cell characterization, CD4+ anti-alpha B-crystallin T cells secreting high levels of interferon-gamma are similarly identified in MS and healthy donors. In conclusion, the peripheral response towards the myelin antigen alpha B-crystallin is neither quantitatively nor qualitatively peculiar to MS, in contrast to the theoretical paradigm suggesting peripheral activation of myelin-reactive T cells to be the prerequisite for MS induction.

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.

Analysis of immunoregulatory T-helper cell subsets in patients with multiple sclerosis: relapsing-progressive course correlates with enhanced T H1, relapsing-remitting course with enhanced T H0 reactivity

In this study, we analysed the recall antigen-induced cytokine production by peripheral blood mononuclear cells (PBMC) from 31 patients with multiple sclerosis (MS) with a relapsing-remitting (rr) and a relapsing-progressive (rp) course and from 40 healthy controls. Cells were stimulated with purified protein derivative (PPD; type 1 response) and tetanus toxoid (TT; type 2 response). Cytokines were determined in the supernatants by ELISA. One of the interesting findings was that healthy controls showed more frequently an IL-5 production after incubation with TT than MS-patients (68% vs.37%; p<0.01), while the type 1 reactivity was only slightly enhanced in MS patients as compared to the controls. However, within the MS patients, there was a significant difference in the incidence of the type 1 reactivity comparing patients with an rp and an rr course (60% vs. 24%; p<0.05). Furthermore, the frequency of a type 0 profile (simultaneous PPD-induced IFN-gamma and TT-induced IL-5 production) was fourfold higher in rr than in the rp patients (43% vs. 10%, p<0.05). In vitro analysis of cytokine profiles in MS could therefore be an interesting approach to evaluate the prognosis of MS (rr vs. rp) already at the beginning of the disease. Thus, it seems that the presence of a type 0 profile is a valid indicator for a favorable course, while a type 1 profile is rather associated with rp MS.

Insights into the immunopathogenesis of multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS). Significant progress has been made in our understanding of the etiology of MS. MS is widely believed to be an autoimmune disease that results from aberrant immune responses to CNS antigens. T cells are considered to be crucial in orchestrating an immunopathological cascade that results in damage to the myelin sheath. This review summarizes the currently available data supporting the idea that myelin reactive T cells are actively involved in the immunopathogenesis of MS. Some of the therapeutic strategies for MS are discussed with a focus on immunotherapies that aim to specifically target the myelin reactive T cells.

Multiple sclerosis complexity in selected populations: the challenge of Sardinia, insular Italy

Several lines of evidence indicate a genetic contribution to multiple sclerosis (MS) both in terms of predisposition to the disease and of immunological mechanisms which are known to play crucial roles in MS pathogenesis. The presence of high- and low-risk areas for MS in neighbouring regions supports the theory that MS predisposition is influenced by a complex interaction of genetic and environmental factors. Therefore, the use of genetically homogeneous and geographically isolated populations becomes an increasing requirement to reduce biasing biological variables. Sardinians fulfil these conditions well because of their different phylogeny from Europeans and the unique selective pressures which shaped their genome. Sardinians display amongst the highest MS prevalence rates world-wide and increasing MS incidence rates over time. Also, MS in Sardinia is linked to distinct human leucocyte antigen (HLA) alleles and associated to different patterns of cytokine production from lymphoid cells of different HLA subtypes. In this context, recent findings and future perspectives on the peculiarities of Sardinian MS concerning genetic, immunological and epidemiological aspects are presented. So far, our results indicate that variations at the level of territorial distribution and HLA-association are present which render MS heterogeneous even in this ethnically homogeneous population.

Proteolytic balance in patients with multiple sclerosis during interferon treatment

Multiple sclerosis (MS) is a progressive, inflammatory, demyelinating disease. An altered cytokine network has been reported to occur during the disease, and its pathogenetic role has been hypothesized. To date, interferon-beta (IFN-beta) is the most effective and reliable therapy in the majority of MS patients, although the mechanisms underlying its therapeutic effects are not fully understood. Breakdown of the blood-brain barrier (BBB) with consequent extravasation of the T cells and their invasion of the brain parenchyma seems to be one of the most important steps in the pathogenesis of the disease. Matrix metalloproteinease-2 (MMP-2) and MMP-9 are enzymes with proteolytic activities toward extracellular matrix ECM components. They are physiologically balanced by the MMP tissue inhibitors TIMP-2 and TIMP-1, so that proteolysis occurs as the result of increased MMP or decreased TIMP levels. In 38 patients with MS, MMP-2 and TIMP-1 levels were similar before and after 9 months of IFN-beta therapy, whereas MMP-9 levels significantly decreased and TIMP-2 levels significantly increased in comparison to values obtained before treatment. These results suggest that IFN-beta modulates T cell activities, including MMP and TIMP production, thus contributing either to maintaining the integrity of the BBB or to slowing the progression of the disease.

The human T cell response to myelin oligodendrocyte glycoprotein: a multiple sclerosis family-based study

Myelin oligodendrocyte glycoprotein (MOG) is an encephalitogenic myelin protein and a likely autoantigen in human multiple sclerosis (MS). In this work, we describe the fine specificity and cytokine profile of T cell clones (TCC) directed against MOG in three nuclear families, comprised of four individuals affected with MS and their HLA-identical siblings. TCC were generated from PBMC by limiting dilution against a mixture of eleven 20-mer overlapping peptides corresponding to the encephalitogenic extracellular domain of human MOG (aa 1-120). The frequency of MOG peptide-reactive T cells was surprisingly high (range, 1:400 to 1:3,000) and, unexpectedly, cloning efficiencies were highest at low seeding densities of 10(2) or 10(3) PBMC per well. A total of 235 MOG peptide-reactive TCC were produced, all of which were CD4(+)CD8(-)TCRalphabeta(+)TCRgammadelta(-). All 11 MOG peptides were recognized by the TCC, and different epitopes of MOG appeared to be immunodominant in the HLA-identical siblings. The patterns of cytokine secretion by TCC from single individuals were generally similar. The healthy individuals exhibited Th2-, Th0-, and T regulatory cell 1-like cytokine profiles, whereas TCC from one sibling with MS had a striking Th1-like phenotype, producing high levels of IFN-gamma and TNF-alpha, and low IL-4 levels. Thus, MOG-reactive T cells appear to constitute an important part of the natural T cell repertoire, a finding that could contribute to the development of autoimmunity to this protein.

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

In multiple sclerosis (MS), T-cells are considered to be critical in coordinating an immunopathological cascade that results in myelin damage. We investigated whether clinical disease activity or brain inflammatory activity as measured by magnetic resonance imaging (MRI) was associated with changes in autoreactive T-cell reactivities in MS patients. To this end, a longitudinal study was performed in which T-cell-related immune parameters and clinical parameters (including MRI) were monitored in seven relapsing-remitting (RR) MS patients and two healthy controls with bimonthly intervals over a period of 18 months. The serial evaluation of antimyelin (MBP, PLP, MOG) T-cell responses revealed highly dynamic shifts and fluctuations from one pattern to another in a patient-dependent manner. In some of the patients, changes in T-cell-related immune variables were found to concur with MRI activity and generally preceded clinical relapses. These alterations include: increased number of myelin-reactive IFN-gamma secreting T-cells, detection of clonally expanded myelin-reactive T-cells, elevated proinflammatory and decreased antiinflammatory cytokine production, upregulation of ICAM-1 membrane expression and highly increased serum levels of soluble VCAM-1. However, not all exacerbations and MRI changes were associated with changes in antimyelin reactivity. Some of the observed immune alterations were also detected in the healthy controls, indicating that additional regulatory mechanisms-which may be defective in MS-play a role in the downregulation of potentially pathological T-cell responses. In conclusion, this study provides further support for an important role of myelin-reactive T-cells in the pathogenesis of MS. In addition, the observed dynamic changes in the antimyelin T-cell reactivity pattern may be a major obstacle for the development of antigen-specific immunotherapies.

Elevated Bcl-X(L) levels correlate with T cell survival in multiple sclerosis

T cell resistance towards apoptotic elimination by activation-induced cell death (AICD) might be a crucial pathogenic feature of multiple sclerosis (MS). Since the Bcl-2 family is critically involved in the regulation of apoptosis, we investigated the protein expression of Bcl-2, Bcl-X(L), and Bax in peripheral blood mononuclear cells (PBMC) of 23 MS patients and 29 control subjects. An in vitro model of AICD, which exemplifies the elimination of antigen-reactive T cells in vivo, was used as an indication of T cell susceptibility or resistance towards apoptosis. Increased expression of the survival factor Bcl-X(L), which directly correlated with a resistance towards AICD, was observed in peripheral immune cells of MS patients. In contrast to Bcl-X(L), no differences were found in the protein expression of Bcl-2 and Bax between patients and controls. Our data indicate that the anti-apoptotic factor Bcl-X(L), responsible for T cell resistance towards apoptosis, might be an important factor in the MS pathogenesis and a potential target for therapeutic intervention.

Regulatory effects of estriol on T cell migration and cytokine profile: inhibition of transcription factor NF-kappa B

The protective role of pregnancy in autoimmune conditions, such as multiple sclerosis (MS), is potentially associated with immune regulation by sex hormones produced during pregnancy. This study was undertaken to examine the regulatory effects of estriol on the T cell functions, including transmigration and the cytokine production. The results revealed for the first time that estriol significantly inhibited T cell transmigration at a concentration range typical of pregnancy, which correlated with decreased T cell expression of matrix metalloproteinase-9. Estriol was also found to alter the cytokine profile of T cells toward Th2 phenotype by up-regulating the production of IL-10 and inhibiting TNFalpha secretion of T cells. However, the inhibitory effects of estriol on T cells were not antigen-dependent. Further characterization indicated that estriol inhibited nuclear transcription factor kappa B (NF-kappa B), which controls a variety of immune-related genes. This study provides new evidence that estriol is a potent regulator for the T cell functions potentially through its interaction with the NF-kappa B signaling pathway.

HLA-DR 15 is associated with female sex and younger age at diagnosis in multiple sclerosis

BACKGROUND

The association between multiple sclerosis and class II alleles of the major histocompatibility complex, in particular the DRB1*1501-DQB1*0602 haplotype, is well established but their role in determining specific features of this clinically heterogeneous disease is unknown as few studies involving large sample sizes have been performed.

METHODS

729 patients with multiple sclerosis were typed for the HLA DR15 phenotype. All patients underwent clinical assessment and a detailed evaluation of their clinical records was undertaken.

RESULTS

The presence of DR15 was associated with younger age at diagnosis and female sex but there was no association with disease course (relapsing-remitting or secondary progressive v primary progressive type), disease outcome, specific clinical features (opticospinal v disseminated form), diagnostic certainty (clinically and laboratory supported definite v clinically probable multiple sclerosis), and paraclinical investigations including the presence of oligoclonal bands in the CSF or characteristic abnormalities on MRI imaging of the central nervous system.

CONCLUSION

Even though DR15 carriers are more likely to be female and prone to an earlier disease onset, the results indicate that there is no association with other specific clinical outcomes or laboratory indices examined here. This suggests that DR15 exerts a susceptibility rather than disease modifying effect in multiple sclerosis.

Peripheral blood cell bulk cultures are not suitable for the analysis of the genetic control of T-cell cytokine function

Recently evidence has been provided for a genetic control of T-cell dependent cytokine production by HLA-class II. Candidate genes in multiple sclerosis, a T-cell mediated autoimmune disease, are the disease-associated DR2, DQ6, Dw2 haplotype. Previous observations by us and others imply a HLA-DR2 dependent propensity of antigen-specific T-cell lines to produce increased amounts of TNF-alpha/beta. Here, we tested a possible association between HLA or disease status with cytokine production employing the simple and widely used method of bulk cultures. Peripheral blood cells of 48 patients and 68 healthy individuals were analyzed. We observed no significant differences of the cytokine production in relation to disease status or any HLA polymorphism. Our data indicate that, in contrast to monoclonal T-cell cultures, bulk cultures are not suitable to detect immunogenetic control of T-cell function.

Characterization of the human T cell response against the neuronal protein synapsin in patients with multiple sclerosis

Although multiple sclerosis (MS) is considered primarily as a demyelinating disease, neuronal damage is abundant and correlates with the neurological deficit. Therefore, we investigated the frequency and characteristics of human T cells specific for synapsin-a neuronal protein highly conserved among species. Synapsin specific T cell responses were detected at a frequency similar to that of MBP specific T cells in MS patients, one patient with acute demyelinating encephalomyelitis (ADEM) and controls. Long-term T cell lines specific for synapsin exhibited a CD3(+), CD4(+), CD8(-) phenotype and produced high amounts of tumor-necrosis-factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) after antigen specific stimulation, whereas lymphotoxin (LT), interleukin-4 (IL-4) and interleukin-10 (IL-10) were detectable in smaller quantities.

The neuroimmunology of multiple sclerosis: possible roles of T and B lymphocytes in immunopathogenesis

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system white matter. The association of the disease with MHC genes, the inflammatory white matter infiltrates, similarities with animal models, and the observation that MS can be treated with immunomodulatory and immunosuppressive therapies support the hypothesis that autoimmunity plays a major role in the disease pathology. Evidence supports activated CD4+ myelin-reactive T cells as major mediators of the disease. In addition, a renewed interest in the possible contribution of B cells to MS immunopathology has been sparked by nonhuman primate and MS pathological studies. This review focuses on the immunopathology of MS, outlining the hypothetical steps of tolerance breakdown and the molecules that play a role in the migration of autoreactive cells to the CNS. Particular focus is given to autoreactive T cells and cytokines as well as B cells and autoantibodies and their role in CNS pathogenesis in MS.

Antigen specific immunotherapy of multiple sclerosis

The development of antigen specific therapy for multiple sclerosis (MS) involves specifically suppressing undesired immune responses targeting the myelin sheath and underlying axon. We have recently reported some success with altered peptide ligands for a major target of the autoimmune response in MS. Antigen specific therapy has the potential to suppress undesirable autoimmunity, while leaving the rest of the immune system intact. Induction of an antigen specific Th1-to-Th2 shift could achieve this aim, once side effects, such as allergic responses, are minimized with optimal dosing.

T-cell reactivity to multiple myelin antigens in multiple sclerosis patients and healthy controls

Myelin proteins, including myelin basic protein (MBP), proteolipid protein (PLP) and myelin oligodendrocyte glycoprotein (MOG) are candidate autoantigens in MS. It is not clear whether MS patients show a predominant reactivity to one or several myelin antigens. We evaluated the IFN-gamma production induced by MBP and MOG and selected MBP-, MOG- and PLP-peptides in MS patients and healthy controls using the IFN-gamma ELISPOT assay. Most MS patients and healthy controls showed a heterogeneous anti-myelin T-cell reactivity. Interestingly in MS patients a positive correlation was found between the anti-MOG and anti-MBP T-cell responses. No myelin peptide was preferentially recognized among the peptides tested (MBP 84-102, 143-168, MOG 1-22, 34-56, 64-86, 74-96, PLP 41-58, 184-199, 190-209). In addition the frequency of IL2R+ MBP reactive T-cells was significantly increased in blood of MS patients as compared with healthy subjects, indicating that MBP reactive T-cells exist in an in vivo activated state in MS patients. Most of the anti-MBP T-cells were of the Th1-type because reactivity was observed in IFN-gamma but not in IL-4 ELISPOT-assays. Using Th1 (IL-12) and Th2 (IL-4) promoting conditions we observed that the cytokine secretion pattern of anti-MBP T-cells still is susceptible to alteration. Our data further indicate that precursor frequency analysis of myelin reactive T-cells by proliferation-based assays may underestimate the true frequency of myelin specific T-cells significantly.

Immunomodulatory effects of interferon beta-1a in multiple sclerosis

Several studies have established a role for interferon beta (IFNbeta) as a treatment for relapsing-remitting multiple sclerosis (MS). IFNbeta has been reported to decrease the relapse rate, relapse severity, progression of disability and development of new brain lesions. Its mechanisms of action, however, remain unclear. We hypothesize that immunomodulatory effects of IFNbeta may underlie its clinical efficacy. We used intracellular cytokine flow cytometry to analyze the effects of IFNbeta-1a on expression of the anti-inflammatory cytokine, IL-10, and its effects on major co-stimulatory molecules in MS patients. We found that peripheral blood mononuclear cells (PBMC) produced more IL-10 following in vitro or in vivo treatment with IFNbeta-1a. The primary cellular sources of IL-10 were monocytes and CD4(+) T lymphocytes. IL-10 production in response to IFNbeta-1a was increased in unseparated PBMC compared to purified lymphocyte cultures, indicating that interaction between monocytes and lymphocytes may influence IL-10 production in response to IFNbeta-1a. Using flow cytometry, we monitored the ex vivo expression of two major co-stimulatory pairs-B7/CD28 and CD40/CD40L-before and after intramuscular IFNbeta-1a treatment of MS patients. IFNbeta-1a lowered the expression of B7.1 on circulating B cells and increased B7.2 expression on monocytes. CD40 expression on B cells was down-regulated, but CD40 on monocytes was up-regulated by IFNbeta-1a treatment. These data suggest that co-stimulatory molecules are modulated by IFNbeta, providing a possible mechanism for its in vivo immune regulatory effects.

Aberrant T cell responses to myelin antigens during clinical exacerbation in patients with multiple sclerosis

Multiple sclerosis (MS) is a demyelinating disease of presumed T cell autoimmunity against self myelin. We hypothesized that if myelin-reactive T cells are associated with the disease processes, they may undergo activation and expansion during acute exacerbation. In this study, we examined the precursor frequency, epitope recognition and cytokine profile of myelin-reactive T cells in 14 relapsing/remitting MS patients during exacerbation and remission. The study revealed that T cells recognizing the immunodominant peptides of candidate myelin antigens, including myelin basic protein (MBP), proteolipid protein and myelin oligodendrocyte glycoprotein, occurred at increased precursor frequency during acute exacerbation. The T cell responses to MBP focused on the immunodominant regions (residues 83-99 and 151-170) during exacerbation and shifted toward other epitopes of MBP at the time of remission. Furthermore, there was a marked increase in the production of T(h)1 cytokines among T cell lines obtained during exacerbation compared to those obtained during remission. The study demonstrated that myelin-reactive T cells underwent selective activation and expansion during acute MS exacerbation. In contrast, myelin-reactive T cells found during remission in the same patients generally resembled those identified in healthy controls with some discrepancies. The findings suggest potential association of aberrant myelin-reactive T cell responses with acute exacerbation in MS, which may reflect transient activation of myelin-reactive T cell populations of pathogenic potential.

Multiple sclerosis associated amino acids of polymorphic regions relevant for the HLA antigen binding are confined to HLA-DR2

Among the candidate genes for multiple sclerosis (MS), the strongest influence is conferred by human leucocyte antigen (HLA) class II genes, in particular the DR2, DQ6, Dw2 haplotype (DRB1*1501, DQA1*0102, DQB1*0602). Similar to other autoimmune diseases, it is not clear yet how the presence of a specific HLA-DR or -DQ molecule translates into an increased disease susceptibility. Previous observations by us and others imply a HLA-DR2 dependent propensity of antigen-specific T-cell lines to produce increased amounts of TNF-alpha/beta as one mechanism how DR2 could contribute to susceptibility. In this article, we investigated the distribution of polymorphic stretches of the DRB1, DQA1, and DQB1 chains known to be relevant for antigen binding, in 66 unrelated patients with relapsing remitting MS and 210 unrelated controls. We found a significant association with disease for the appearance of proline at position 11, arginine at position 13, and alanine at position 71 of HLA-DRbeta1. Surprisingly, we identified only residues preferentially expressed in the MS group that were related to HLA-DR2. Thus, the contribution of HLA class II to the pathogenesis of MS is not mediated by allele-overlapping antigen binding sites, but is confined to the disease associated HLA allele.

Induction of a non-encephalitogenic type 2 T helper-cell autoimmune response in multiple sclerosis after administration of an altered peptide ligand in a placebo-controlled, randomized phase II trial. The Altered Peptide Ligand in Relapsing MS Study Group

In this 'double-blind', randomized, placebo-controlled phase II trial, we compared an altered peptide ligand of myelin basic protein with placebo, evaluating their safety and influence on magnetic resonance imaging in relapsing-remitting multiple sclerosis. A safety board suspended the trial because of hypersensitivity reactions in 9% of the patients. There were no increases in either clinical relapses or in new enhancing lesions in any patient, even those with hypersensitivity reactions. Secondary analysis of those patients completing the study showed that the volume and number of enhancing lesions were reduced at a dose of 5 mg. There was also a regulatory type 2 T helper-cell response to altered peptide ligand that cross-reacted with the native peptide.

Glatiramer acetate (copolymer-1)-specific, human T cell lines: cytokine profile and suppression of T cell lines reactive against myelin basic protein

Glatiramer acetate (GA), represents an established treatment of relapsing/remitting multiple sclerosis (MS). The mechanisms responsible for the effect of GA are not fully understood. We generated GA-, myelin basic protein (MBP)- and purified protein derivative (PPD)-specific T cell lines from three MS patients and one healthy donor. The GA-specific lines were CD3+, CD4+, CD8- and produced tumor-necrosis-factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), interleukin-4 (IL-4), interleukin-6 (IL-6) and interleukin-10 (IL-10) after stimulation with GA in the presence of irradiated peripheral blood mononuclear cells. MBP-specific T cell lines showed an identical phenotype and secreted TNF-alpha, IFN-gamma, IL-4, IL-10, but not IL-6. Co-culture experiments demonstrated, that GA-specific T cell lines have the capability to suppress the proliferation of MBP-specific T cell lines.

Characterization of T cell lines derived from glatiramer-acetate-treated multiple sclerosis patients

We analyzed the effects of glatiramer acetate (GA) therapy on in vitro proliferative responses and cytokine production by lymphocytes derived from multiple sclerosis patients receiving this therapy. We confirmed that lymphocytes derived from GA naïve patients show a high frequency of response when initially exposed to GA in vitro; this frequency decreased following GA therapy. The frequency of lymphocytes responding to whole MBP stimulation did not change with GA therapy. GA- and MBP-specific T cell lines generated from these patients by repeated cycles of in vitro stimulation did not cross react. Some (23%) whole MBP-reactive T cell lines did cross react with MBP peptide 83-99. The mean levels of interferon (IFN) gamma secretion and the mean ratio of IFN-gamma/IL-5 were lower for GA-reactive cell lines, derived from patients both prior to and during GA therapy, compared to MBP-reactive T cell lines. The proportion of IFN-gamma(+) cells in unfractionated lymphocyte preparations derived from the GA-treated patients did not differ from that found for healthy controls. Our findings indicate that GA-reactive T cell lines derived from GA-treated MS patients continue to show a relative Th2 cytokine bias consistent with a bystander suppressor function. GA treatment is not associated with a cytokine phenotype shift in the total T cell or MBP-reactive T cell populations.

Cytokine secretion profile of myelin basic protein-specific T cells in multiple sclerosis

Multiple sclerosis (MS) is a demyelinating disease of the central nervous system with a presumed autoimmune pathogenesis involving autoantigen-specific CD4+ T cells and cytokines. A similar frequency of T cells responding to myelin basic protein (MBP), a putative target in MS, has been observed in MS patients and controls. To dissect the differences between MBP-specific T cells in patients and controls, we have analyzed the cytokine secretion profile of such autoreactive T cells. MBP-specific T cell clones (TCC) were isolated from the peripheral blood of MS patients and controls by limiting dilution. Expression of mRNA for interferon-gamma (IFN-gamma), interleukin (IL)-4, IL-10, tumor necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta (TGF-beta) was assessed by polymerase chain reaction whereas secretion of cytokine protein was measured by ELISA. MBP-specific TCC exhibited a heterogeneous cytokine secretion profile with clones displaying Th1, Th2 and Th0 phenotypes. A significant difference in the distribution of the cytokine profile was noted between MS patients and controls. Although the frequency of Th1 secreting MBP-reactive TCC was similar between MS patients and controls, stable MS patients had a significant association with the Th0 phenotype whereas healthy individuals were associated with the Th2 phenotype. In comparison to control TCC, MBP-specific TCC from MS patients secreted increased amounts of IFN-gamma, IL-4 and IL-10 and decreased quantities of TGF-beta. Thus, these studies suggest that there is a dysregulation in the balance between pro-inflammatory Th1 and anti-inflammatory Th2 cytokines in MS. It appears that the presence of Th1 secreting autoreactive T cells in healthy individuals may be counterbalanced by the presence of cells secreting Th2 cytokines and by the augmented production of the immunosuppressive cytokine TGF-beta, whereas in MS there is a decrease in these anti-inflammatory agents.

Myelin reactive T cells after T cell vaccination in multiple sclerosis: cytokine profile and depletion by additional immunizations

Pathogenic autoreactive T cells can be targeted by T cell vaccination (TCV), a procedure in which patients are immunized with autologous attenuated pathogenic T cells. We reported previously that TCV with myelin basic protein (MBP) reactive T cell clones in multiple sclerosis (MS) patients induced T cell immune responses, resulting in a clonal depletion of MBP reactive T cells in all patients. Five years after TCV, MBP reactive T cells were observed in five out of nine MS patients. These clones had a different clonal origin from those isolated before vaccination. We have studied the cytokine profile, cytotoxicity and epitope specificity of these reappearing clones. Our data indicate that the clones express similar effector functions as those isolated before TCV, suggesting that they also could play a pathogenic role in the disease. We demonstrated that these clones can be depleted by an additional sequence of immunizations. These findings may be relevant to other T cell targeted immunotherapies for MS and other autoimmune diseases.

Th1 and Th2 Deviation of Myelin-Autoreactive T Cells by Altered Peptide Ligands Is Associated with Reciprocal Regulation of Lck, Fyn, and ZAP-70

Th0 clones recognizing an immunodominant peptide of myelin basic protein (residues 83–99) were derived from patients with multiple sclerosis. We demonstrate that analogue peptides with alanine substitution at Val86 and His88 had a unique partial agonistic property in inducing Th0 →Th1 and Th0 →Th2 deviation of the myelin basic protein-reactive T cell clones, respectively. Th0 to Th1 deviation induced by peptide 86V→A correlated with up-regulation of Fyn and ZAP-70 kinase activities. Conversely, Th0 to Th2 deviation induced by peptide 88H→A was associated with complete failure to activate Fyn and ZAP-70 kinases. The observed Th1 and Th2 shift also correlated, to a lesser extent, with Lck kinase activity that was down-regulated with Th1 deviation and increased with Th2 deviation in some T cell clones. We demonstrated that the Th1 and Th2 shift induced by the analogue peptides was a reversible process, as the T cell clones previously exposed to either 86V→A or 88H→A peptide could revert to an opposite phenotype when rechallenged reciprocally with a different analogue peptide. The study has important implications in our understanding of regulation of TCR-associated tyrosine kinases by altered peptide ligands and its role in cytokine regulation of autoreactive T cells.

Immune regulation and CNS autoimmune disease

The central nervous system is a demonstrated target of both clinical and experimental immune mediated disorders. Immune regulatory mechanisms operative at the levels of the systemic immune system, the blood brain barrier, and within the CNS parenchyma are important determinants of the intensity and duration of the tissue directed injury. Convergence of research, involving direct manipulation of specific cells and molecular mediators in animal models and in vitro analysis of human immune and neural cells and tissues, is providing increasing insight into the role of these immune regulatory functions and their potential to serve as therapeutic targets.