Involvement of distinct murine T-cell receptors in the autoimmune encephalitogenic response to nested epitopes of myelin basic protein

The re-emergence of antigen-specific tolerance as a potential therapy for MS

Ideal therapy for inflammatory disease in the nervous system would preserve normal immune function, while suppressing only the pathologic immune responses that damage tissue and allowing for repair. In principle, antigen-specific therapy would eradicate unwanted adaptive immune responses-antibody and T-cell mediated--while preserving the integrity of other adaptive responses to infectious agents and retaining the ability to fight malignancy. However, at this time, for multiple sclerosis (MS) we do not have compelling evidence that would support any particular dominant immune response to any specific antigen or even a limited group of antigens. In fact, there are adaptive immune responses to a wide swathe of proteins and lipids found on neurons and myelin in MS. Unless controlling a few of the known immune responses is sufficient, antigen-specific therapy in MS may not have enough of an impact to modulate clinical outcome. However, in other neuroinflammatory conditions, such as neuromyelitis optica, the adaptive immune response is highly focused. Trials of antigen-specific therapy for neuroinflammatory disease might first be tested in diseases with a more limited adaptive immune response like neuromyelitis optica. The likelihood of a significant success for this therapeutic strategy might then ensue.

Molecular mimicry between Mycobacterium leprae proteins (50S ribosomal protein L2 and Lysyl-tRNA synthetase) and myelin basic protein: a possible mechanism of nerve damage in leprosy

Autoantibodies against various components of host are known to occur in leprosy. Nerve damage is the primary cause of disability associated with leprosy. The aim of this study was to detect the level of autoantibodies and lympho-proliferative response against myelin basic protein (MBP) in leprosy patients (LPs) and their correlation with clinical phenotypes of LPs. Further, probable role of molecular mimicry in nerve damage of LPs was investigated. We observed significantly high level of anti-MBP antibodies in LPs across the spectrum and a positive significant correlation between the level of anti-MBP antibodies and the number of nerves involved in LPs. We report here that 4 B cell epitopes of myelin A1 and Mycobacterium leprae proteins, 50S ribosomal L2 and lysyl tRNA synthetase are cross-reactive. Further, M. leprae sonicated antigen hyperimmunization was responsible for induction of autoantibody response in mice which could be adoptively transferred to naive mice. For the first time our findings suggest the role of molecular mimicry in nerve damage in leprosy.

Inverse Vaccination to Silence Immunity to Myelin in Multiple Sclerosis

The adaptive immune response in multiple sclerosis is complex. We have devised large scale arrays to measure the antibody response to myelin proteins and lipids. Despite the widespread immune responses to myelin, we have devised an inverse vaccine aimed at turning off key drivers of this diverse response. Clinical trials in patients with multiple sclerosis show that it is possible to constrain antibody responses to myelin on a large scale with this approach.

DQB1*06:02-Associated Pathogenic Anti-Myelin Autoimmunity in Multiple Sclerosis-Like Disease: Potential Function of DQB1*06:02 as a Disease-Predisposing Allele

Susceptibility to multiple sclerosis (MS) has been linked mainly to the HLA-DRB1 locus, with the HLA-DR15 haplotype (DRB1*1501-DQA1*0102-DQB1*0602-DRB5*0101) dominating MS risk in Caucasians. Although genes in the HLA-II region, particularly DRB1*1501, DQA1*0102-DQB1*0602, are in tight linkage disequilibrium, genome-wide-association, and gene candidate studies identified the DRB1*15:01 allele as the primary risk factor in MS. Many genetic and immune-functional studies have indicated DRB1*15:01 as a primary risk factor in MS, while only some functional studies suggested a disease-modifying role for the DRB5*01 or DQB1*06 alleles. In this respect, the susceptibility of DRB1*15:01-transgenic (Tg) mice to myelin basic protein- or myelin oligodendrocyte glycoprotein-induced MS-like disease is consistent with primary contribution of DRB1*15:01 to HLA-DR15+ MS. The studies summarized here show that susceptibility to MS-like disease, induced in HLA-“humanized” mice by myelin oligodendrocytic basic protein or by the proteolipid protein, one of the most prominent encephalitogenic target antigens implicated in human MS, is determined by DQB1*06:02, rather than by the DRB1*15:01 allele. These findings not only offer a rationale for a potential role for DQB1*06:02 in predisposing susceptibility to MS, but also suggest a more complex and differential functional role for HLA-DR15 alleles, depending on the primary target myelin antigen. However, the conflict between these findings in HLA-Tg mice and the extensive genome-wide-association studies, which could not detect any significant effect from the DQB1*06:02 allele on MS risk, is rather puzzling. Functional analysis of MS PBLs for DQB1*06:02-associated anti-myelin autoimmunity may indicate whether or not DQB1*06:02 is associated with MS pathogenesis.

Identification of a second mimicry epitope from Acanthamoeba castellanii that induces CNS autoimmunity by generating cross-reactive T cells for MBP 89-101 in SJL mice

We had previously reported that Acanthamoeba castellanii (ACA) contains a mimicry epitope for proteolipid protein 139-151 capable of inducing central nervous system (CNS) autoimmunity in SJL/J mice. We now present evidence that ACA also contains a mimicry epitope for myelin basic protein (MBP) 89-101, a derivative from amoebic nicotinamide adenine dinucleotide dehydrogenase subunit 2 (NAD). The epitope, NAD 108-120, contains a discontinuous stretch of six amino acids in the core region (VVFFKNIILIGFL) sharing 46% identity with MBP 89-101 (VHFFKNIVTPRTP; identical residues are underlined). SJL mice immunized with NAD 108-120 develop encephalomyelitis similar to the disease induced by the cognate peptide. We demonstrate that NAD 108-120 induces T cells that cross-react with MBP 89-101; the antigen-sensitized T cells, which produce predominantly T helper (T(h)) 1 and T(h)17 cytokines, transfer disease in naive SJL recipients reminiscent of the disease induced with MBP 89-101. This is the first report to demonstrate that a solitary microbe can induce CNS autoimmunity by generating cross-reactive T cells for multiple myelin antigens.

Altered peptide ligands of myelin basic protein ( MBP87-99 ) conjugated to reduced mannan modulate immune responses in mice

Mutations of peptides to generate altered peptide ligands, capable of switching immune responses from T helper 1 (Th1) to T helper 2 (Th2), are promising candidates for the immunotherapy of autoimmune diseases such as multiple sclerosis (MS). We synthesized two mutant peptides from myelin basic protein 87-99 (MBP(87-99)), an immunodominant peptide epitope identified in MS. Mutations of residues K(91) and P(96), known to be critical T-cell receptor (TCR) contact sites, resulted in the mutant peptides [R(91), A(96)]MBP(87-99) and [A(91), A(96)]MBP(87-99). Immunization of mice with these altered peptide ligands emulsified in complete Freund's adjuvant induced both interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) responses compared with only IFN-gamma responses induced to the native MBP(87-99) peptide. It was of interest that [R(91), A(96)]MBP(87-99) conjugated to reduced mannan induced 70% less IFN-gamma compared with the native MBP(87-99) peptide. However, [A(91), A(96)]MBP(87-99) conjugated to reduced mannan did not induce IFN-gamma-secreting T cells, but elicited very high levels of interleukin-4 (IL-4). Furthermore, antibodies generated to [A(91), A(96)]MBP(87-99) peptide conjugated to reduced mannan did not cross-react with the native MBP(87-99) peptide. By molecular modelling of the mutant peptides in complex with major histocompatibility complex (MHC) class II, I-A(s), novel interactions were noted. It is clear that the double-mutant peptide analogue [A(91), A(96)]MBP(87-99) conjugated to reduced mannan is able to divert immune responses from Th1 to Th2 and is a promising mutant peptide analogue for use in studies investigating potential treatments for MS.

T cell receptors in an IL-10-secreting amino acid copolymer-specific regulatory T cell line that mediates bystander immunosuppression

The T cell receptors from the regulatory IL-10-secreting T cell line induced by the random amino acid copolymers poly(F,Y,A,K,)n in SJL mice (H-2(s)) have been characterized, cloned, sequenced and expressed both in 293T cells and in 2 different TCR alpha(-)/beta(-) T cell hybridomas. The usage of TCR alpha and beta V regions in the cell line was oligoclonal. Four TCR alpha/beta pairs cloned from single cells of the T cell line were inserted into a retrovirus vector linked by an oligonucleotide encoding the 2A peptide that spontaneously cleaves in vivo. After cotransfection of this vector with a CD3 vector into the 293T cells, the TCR were surface expressed. Moreover, after transduction into the 2 T cell hybridomas, all 4 were functional as evidenced by their response to stimulation by poly(F,Y,A,K)n. All 4 pairs were Valpha3.2(3.5)/Vbeta14, a prominent clonotype found in the poly(F,Y,A,K)n-specific T cell line. These V regions are identical to those recently found in a regulatory T cell line that secretes both IL-4 and IL-10 induced in B10.PL mice with a different MHC hapotype (H-2(u)) by a small peptide obtained from an autoimmune TCR of that strain. These data lead to a hypothesis regarding the origin of the epigenetic modifications that lead to selective cytokine secretion in T cells.

Animal models of multiple sclerosis

Since its first description, experimental autoimmune encephalomyelitis, originally designated experimental allergic encephalitis (EAE), has been proposed as animal model to investigate pathogenetic hypotheses and test new treatments in the field of central nervous system inflammation and demyelination, which has become, in the last 30 years, the most popular animal model of multiple sclerosis (MS). This experimental disease can be obtained in all mammals tested so far, including nonhuman primates, allowing very advanced preclinical studies. Its appropriate use has led to the development of the most recent treatments approved for MS, also demonstrating its predictive value when properly handled. Some of the most exciting experiments validating the use of neural precursor cells (NPCs) as a potential therapeutic option in CNS inflammation have been performed in this model. We review here the most relevant immunological features of EAE in the different animal species and strains, and describe detailed protocols to obtain the three most common clinical courses of EAE in mice, with the hope to provide both cultural and practical basis for the use of this fascinating animal model.

Arthritogenic T cell epitope in glucose-6-phosphate isomerase-induced arthritis

Introduction

Arthritis induced by immunisation with glucose-6-phosphate isomerase (GPI) in DBA/1 mice was proven to be T helper (Th) 17 dependent. We undertook this study to identify GPI-specific T cell epitopes in DBA/1 mice (H-2q) and investigate the mechanisms of arthritis generation.

Methods

For epitope mapping, the binding motif of the major histocompatibility complex (MHC) class II (I-Aq) from DBA/1 mice was identified from the amino acid sequence of T cell epitopes and candidate peptides of T cell epitopes in GPI-induced arthritis were synthesised. Human GPI-primed CD4+ T cells and antigen-presenting cells (APCs) were co-cultured with each synthetic peptide and the cytokine production was measured by ELISA to identify the major epitopes. Synthetic peptides were immunised in DBA/1 mice to investigate whether arthritis could be induced by peptides. After immunisation with the major epitope, anti-interleukin (IL) 17 monoclonal antibody (mAb) was injected to monitor arthritis score. To investigate the mechanisms of arthritis induced by a major epitope, cross-reactivity to mouse GPI peptide was analysed by flow cytometry and anti-GPI antibodies were measured by ELISA. Deposition of anti-GPI antibodies on the cartilage surface was detected by immunohistology.

Results

We selected 32 types of peptides as core sequences from the human GPI 558 amino acid sequence, which binds the binding motif, and synthesised 25 kinds of 20-mer peptides for screening, each containing the core sequence at its centre. By epitope mapping, human GPI325–339 was found to induce interferon (IFN) γ and IL-17 production most prominently. Immunisation with human GPI325–339 could induce polyarthritis similar to arthritis induced by human GPI protein, and administration of anti-IL-17 mAb significantly ameliorated arthritis (p < 0.01). Th17 cells primed with human GPI325–339 cross-reacted with mouse GPI325–339, and led B cells to produce anti-mouse GPI antibodies, which were deposited on cartilage surface.

Conclusions

Human GPI325–339 was identified as a major epitope in GPI-induced arthritis, and proved to have the potential to induce polyarthritis. Understanding the pathological mechanism of arthritis induced by an immune reaction to a single short peptide could help elucidate the pathogenic mechanisms of autoimmune arthritis.

The origin and application of experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is a model of the neuroimmune system responding to priming with central nervous system (CNS)-restricted antigens. It is an excellent model of post-vaccinal encephalitis and a useful model of many aspects of multiple sclerosis. EAE has been established in numerous species and is induced by priming with a large number of CNS-derived antigens. As a consequence, the pathogenesis, pathology and clinical signs vary significantly between experimental protocols. As I describe in this Timeline article, the reductionist approach taken in some lines of investigation of EAE resulted in a reliance on results obtained under a narrow range of conditions. Although such studies made important contributions to our molecular understanding of inflammation, T-cell activation, and MHC restriction, they did not advance as effectively our knowledge of the polyantigenic responses that usually occur in CNS immunopathology and autoimmunity.

A Large Number of T Lymphocytes Recognize Moloney-Murine Leukemia Virus-Induced Antigens, but a Few Mediate Long-Lasting Tumor Immunosurveillance

The CD8(+) T cell response to Moloney-murine leukemia virus (M-MuLV)-induced Ags is almost entirely dominated by the exclusive expansion of lymphocytes that use preferential TCRVbeta chain rearrangements. In mice lacking T cells expressing these TCRVbeta, we demonstrate that alternative TCRVbeta can substitute for the lack of the dominant TCRVbeta in the H-2-restricted M-MuLV Ag recognition. We show that, at least for the H-2(b)-restricted response, the shift of TCR usage is not related to a variation of the immunodominant M-MuLV epitope recognition. After virus immunization, all the potentially M-MuLV-reactive lymphocytes are primed, but only the deletion of dominant Vbeta rescues the alternative Vbeta response. The mechanism of clonal T cell "immunodomination" that guides the preferential Vbeta expansion is likely the result of a proliferative advantage of T cells expressing dominant Vbeta, due to differences in TCR affinity and/or cosignal requirements. In this regard, a CD8 involvement is strictly required for the virus-specific cytotoxic activity of CTL expressing alternative, but not dominant, Vbeta gene rearrangements. The ability of T cells expressing alternative TCRVbeta rearrangements to mediate tumor protection was evaluated by a challenge with M-MuLV tumor cells. Although T cells expressing alternative Vbeta chains were activated and expanded, they were not able to control tumor growth in a long-lasting manner due to their incapacity of conversion and accumulation in the T central memory pool.

The MBP-reactive repertoire is shaped by recognition of minor histocompatibility antigens

While it is known that the degeneracy of T-cell antigen recognition is involved in many aspects of T cell-immunology, its importance in the selection of the T cell repertoire remains an aspect to be better investigated. Here we examined if an intrathymic degenerate T cell recognition mechanism shapes the myelin basic protein (MBP)-reactive repertoire inducing resistance to experimental autoimmune encephalomyelitis (EAE) in some MHC and/or minor histocompatibility antigens (MiHAs) heterozygous F1 mice bearing the H-2(s) susceptibility allele. We found a considerable degree of cross-reactivity between MBP and MiHAs encoded in various EAE resistant mouse strains: (1) MBP-specific T cells can be re-stimulated in vitro by cells expressing these MiHAs and maintain their encephalitogenic activity, and (2) lymphoid cells from parental strains that generate EAE resistant F1 hybrids can induce disease relapse when injected into EAE-susceptible hosts. The results suggest that heterozygosity, through the degeneracy of T cell antigen recognition mechanism, may provide further means to constrain the potential autoreactive repertoire.

Binding of the ELAV-like protein in murine autoimmune T-cells to the nonameric AU-rich element in the 3' untranslated region of CD154 mRNA

The CD154 molecule is important for experimental allergic encephalomyelitis (EAE) which is mediated by autoimmune CD4(+) T-cells. Post-transcriptional instabilization/stabilization of mRNAs, which contain an adenylate uridylate rich element (ARE) in their 3' untranslated region (3'UTR), is regulated in part by binding of ARE-binding proteins to the element. We have investigated the protein which binds to the nonameric ARE in the 3'UTR of CD154 mRNA. A protein which binds to the CD154 ARE was found to exist in a extract prepared from murine autoimmune T-cells activated with myelin basic protein (MBP), and turned out to be mHuR which is a ubiquitous ELAV-like protein. It was found that mHuR was upregulated upon stimulation of the T-cells with a MBP antigen. The CD154 ARE and the ARE in the 3'UTR of tumor necrosis factor-alpha (TNF-alpha) mRNA were competed in binding to mHuR, indicating that both AREs bind to the same site on mHuR. The presence of the CD154 ARE downstream of the luciferase cDNA in a reporter plasmid decreased the translational efficiency, and co-expression of the mHuR slightly increased the translation. These results suggest the possibility that the ELAV-like protein participates in the regulation of the expression of CD154 on the autoimmune T-cells. Modification of the expression of CD154 on autoimmune T-cells by regulating the ELAV-like protein may provide effective therapy for EAE and human multiple sclerosis.

Influence of a dominant cryptic epitope on autoimmune T cell tolerance

The rules governing which T cells are inactivated during peptide-induced tolerance are unclear. Here we show that MBP(89-101) contains three overlapping but distinct T cell epitopes that are restricted by a single major histocompatibility complex (MHC) class II molecule. The dominant epitope is not processed from MBP and is not relevant to the induction of autoimmunity. Pathogenic T cells recognize two minor epitopes that are processed from MBP but are presented only poorly after exposure to MBP(89-101). Induction of immunological tolerance by MBP(89-101) therefore inactivates T cells that recognize the dominant epitope and disease-relevant T cells escape tolerance. The topology of the three epitopes implicates asparagine endopeptidase as the enzyme that controls recognition of this region of MBP. Our results highlight the need to use peptides that mimic the binding of processed antigen fragments to MHC molecules for successful modulation of disease-relevant T cells.

Inhibition of experimental autoimmune encephalomyelitis in SJL mice by oral administration of retro-inverso derivative of encephalitogenic epitope P87-99

Retro-inverso modification of peptides preserves parent peptide overall topology and provides at the same time stability to proteolysis, leading to derivatives with prolonged half-life in vitro and in vivo. In this study the encephalitogenic epitope P87 - 99 of myelin basic protein has been prepared in the retro-inverso form to examine its biological activity in a murine model of multiple sclerosis. Experiments of in vivo T cell tolerance induction in SJL mice revealed that the retro-inverso peptide was able to induce a selective T cell hyporesponsiveness, as measured by a reduction in the proliferative response of lymphnode T cells after antigen challenge. Oral administration of retro-inverso peptide decreased the disease severity significantly and delayed considerably the disease onset in treated mice. Enhancement of resistance to proteolysis by retro-inverso modification of encephalitogenic epitopes may increase the therapeutic value of oral tolerance induction in the treatment of multiple sclerosis and other Th1-associated inflammatory disorders.

Microbial epitopes act as altered peptide ligands to prevent experimental autoimmune encephalomyelitis

Molecular mimicry refers to structural homologies between a self-protein and a microbial protein. A major epitope of myelin basic protein (MBP), p87-99 (VHFFKNIVTPRTP), induces experimental autoimmune encephalomyelitis (EAE). VHFFK contains the major residues for binding of this self-molecule to T cell receptor (TCR) and to the major histocompatibility complex. Peptides from papilloma virus strains containing the motif VHFFK induce EAE. A peptide from human papilloma virus type 40 (HPV 40) containing VHFFR, and one from HPV 32 containing VHFFH, prevented EAE. A sequence from Bacillus subtilis (RKVVTDFFKNIPQRI) also prevented EAE. T cell lines, producing IL-4 and specific for these microbial peptides, suppressed EAE. Thus, microbial peptides, differing from the core motif of the self-antigen, MBPp87-99, function as altered peptide ligands, and behave as TCR antagonists, in the modulation of autoimmune disease.

Delineation of two encephalitogenic myelin basic protein epitopes for DA rats

We studied synthetic peptides that correspond to two regions of the guinea pig myelin basic protein (MBP) molecule which elicit experimental autoimmune encephalomyelitis (EAE) in DA rats. Using truncated peptides, we determined that two encephalitogenic epitopes reside within MBP63-81, a major determinant defined by MBP residues, 63-76, and a minor encephalitogenic epitope defined by residues, 66-81. Experiments with alanine-substituted analogs of MBP63-76 revealed that the HYGSLP sequence is critical for encephalitogenicity. The core epitope within a second encephalitogenic region, MBP101-120, was defined by residues, 106-119. Studies with analogs of this sequence indicated that residues, Leu 111, Phe 114 and Trp 116 are important for T-cell responsiveness.

Anti-T-cell receptor therapy in murine experimental systemic lupus erythematosus

Experimental systemic lupus erythematosus (SLE), similar to that observed after immunization with the human anti-DNA mAb 16/6 Id+, could be induced in mice by injection of 16/6 Id specific T-cell lines. The above T-cell lines were exclusively CD4+ CD8- and the majority of cells expressed the Vbeta8 T-cell receptor (TCR) gene products. Furthermore, lymph node cells of mice immunized with the 16/6 Id were enriched with CD4+ Vbeta8+ T-cells. The TCR used by 16/6 Id-specific T-cells showed a limited homology in their CDR3 junctional regions. Nevertheless, mice injected with the anti-Vbeta8 mAb developed autoantibody titers that were not significantly different from those found in the non-treated, 16/6 Id-injected group.

CDR3 Size Spectratyping and Sequencing of Spectratype-Derived TCR of Spinal Cord T Cells in Autoimmune Encephalomyelitis

To characterize the nature of autoimmune disease-inducing T cells in the target organ, oligoclonal expansion of spinal cord T cells of Lewis rats with experimental autoimmune encephalomyelitis (EAE) was examined by complementarity-determining region 3 (CDR3) size spectratyping. It is known that TCR of in vitro-established myelin basic protein-specific T cell clones and lines have a short CDR3 and that the amino acid sequence in this region is highly preserved. On the basis of these findings, we analyzed 22 spectratypes of the TCR β-chain (Vβ1–20). Among them, only Vβ8.2 and Vβ17 showed oligoclonal expansion of TCR with a short CDR3 at the early stage of EAE. More interestingly, the spectratype profile of Vβ8.2 seen at the early stage was preserved throughout the course of EAE, whereas that of Vβ17 became more diverse at the peak stage of the disease. Analysis of nucleotide and predicted amino acid sequences of Vβ8.2 CDR3 derived from the spectratypes revealed that the clones with CASSDSSYEQYFGPG, which is one of the representative sequences of encephalitogenic T cell clones, constituted the predominant population not only at the early stage but also at the peak and recovery stages (71, 71, and 60%, respectively). These findings imply that although the phenotype of T cells in the target organ diversifies as the autoimmune disease progresses, disease-associated TCR spectratype(s) are preserved throughout the course of the disease. Thus, CDR3 size spectratyping is a powerful tool for the screening of disease-inducing T cells in an autoimmune disease of unknown pathomechanism.

TCRV and TCRJ gene usage in MBP responding T cells from (B10.PL x PL/J)F1 mice is biased towards that of B10.PL mice

We analyzed myelin basic protein (MBP) specific T cell hybridoma clones from (B10.PL x PL/J)F1 mice. MBP-reacting T cell hybridomas from F1 mice preferentially expressed B10.PL TcraV2.3 (53%) and B10.PL TcraV4.2 (13%) with minor expression of TcraV4.4 (13%) gene segments. A dominant expression of TcrbV8.2 (73%) accompanying with TcrbV8.1 (20%) and TcrbV13 (7%) gene segments have been identified in these MBP-reacting T cell hybridomas from F1 mice. There was less restrictive but non-random usage of the TcraJ and TcrbJ gene segments. Overall, the MBP-reacting T cell hybridomas from (B10.PL x PL/J)F1 mice were dominated by the MBP-reacting T cell pattern seen in B10.PL mice.

Amelioration of relapsing experimental autoimmune encephalomyelitis with altered myelin basic protein peptides involves different cellular mechanisms

T-cells specific for a region of human myelin basic protein, amino acids 87-99 (hMBP87-99), have been implicated in the development of multiple sclerosis (MS) a demyelinating disease of the central nervous system. Administration of soluble altered peptide ligand (APL), made by substituting native residues with alanine at either positions 91(91K > A or A91) or 97 (97R > A or A97) in the hMBP87-99 peptide, blocked the development of chronic relapsing experimental autoimmune encephalomyelitis (R-EAE), in the SJL mouse. The non-encephalitogenic APL A91, appears to induce cytokine shifts from Th1 to Th2 in the target T-cells, whereas the encephalitogenic superagonist APL A97 causes deletion of the MBP87-99 responsive cells. Thus, single amino acid changes at different positions in the same peptide epitope can lead to APL capable of controlling auto-immune disease by different mechanisms.

Modulation of experimental allergic encephalomyelitis in mice by immunization with a peptide specific for the gamma delta T cell receptor

This study investigated the role of gamma delta T cells in experimental allergic encephalomyelitis (EAE), a chronic inflammatory disease of the central nervous system (CNS) that resembles multiple sclerosis. The strategy was to assess the effect on EAE of TCR peptide immunization directed against V gamma 6 T cells, shown recently to predominate in the CNS of mice during the early stages of EAE. The data show that TCR peptide immunization specific for V gamma 6 chains does not induce protection against EAE, since the incidence of EAE in TCR treated animals was similar to control mice, and therefore does not affect disease susceptibility per se, but rather alters the development of the disease. Specifically, there was a delay in the onset of EAE and a reduction in disease severity in TCR treated animals, although the effects were not highly significant. These findings suggest a role for gamma delta T cells in the development of EAE; however, further studies are necessary to confirm the specificity of TCR peptide immunization.

Prior exposure to superantigen can inhibit or exacerbate autoimmune encephalomyelitis: T-cell repertoire engaged by the autoantigen determines clinical outcome

Experimental allergic encephalomyelitis (EAE) is inducible in experimental animals immunized with myelin basic protein (MBP), proteolipid protein (PLP) or their peptides. We compared T-cell responses to encephalitogenic epitopes of PLP(43-64) and MBP(Ac1-11) in a single mouse strain, (PL/J x SJL)F1. MBP(1-11)-specific T-cell hybridomas expressed predominantly TCR V beta 8 or V beta 4, while PLP(43-64)-specific hybridomas expressed a diverse TCR repertoire. To analyze the biologic significance of the TCR repertoire (limited vs. diverse) to disease susceptibility, we pretreated mice with a superantigen (SEB), and then induced disease with these autoantigens. Mice injected with SEB and immunized with MBP(Ac1-11) showed significant inhibition of EAE, whereas SEB-pretreated mice immunized with PLP(43-64) had an increased severity of EAE and developed a chronic disease. These data demonstrate that prior exposure to microbial superantigens can significantly alter the autoimmune disease course depending upon the TCR repertoire used by the autoantigen.

Suppressive vaccination with DNA encoding a variable region gene of the T-cell receptor prevents autoimmune encephalomyelitis and activates Th2 immunity

A variable region gene of the T-cell receptor, V beta 8.2, is rearranged, and its product is expressed on pathogenic T cells that induce experimental autoimmune encephalomyelitis (EAE) in H-2u mice after immunization with myelin basic protein (MBP). Vaccination of these mice with naked DNA encoding V beta 8.2 protected mice from EAE. Analysis of T cells reacting to the pathogenic portion of the MBP molecule indicated that in the vaccinated mice there was a reduction in the Th1 cytokines interleukin-2 (IL-2) and interferon-gama. In parallel, there was an elevation in the production of IL-4, a Th2 cytokine associated with suppression of disease. A novel feature of DNA immunization for autoimmune disease, reversal of the autoimmune response from Th1 to Th2, may make this approach attractive for treatment of Th1-mediated diseases like multiple sclerosis, juvenile diabetes and rheumatoid arthritis.

Treatment of relapsing autoimmune encephalomyelitis with T cell receptor V beta-specific antibodies when proteolipid protein is the autoantigen

Monoclonal antibodies (mAbs) directed against the V beta chain of the T cell receptor (TCR) of pathogenic T cells have been used to treat acute murine experimental autoimmune encephalomyelitis (EAE) induced by myelin basic protein (BP). We evaluated anti-V beta mAb for the treatment of relapsing EAE (R-EAE) induced in SJL/J mice by the myelin proteolipid protein (PLP) peptide 139-151. Spinal cord mononuclear cells isolated from mice immunized for R-EAE with PLP 139-151 were shown to express a predominance of V beta 2 and V beta 17 during acute and relapsing disease. T cell lines specific for PLP 139-151 were magnetically sorted to express 80-90% V beta 2. These V beta 2-enriched lines induced typical relapsing demyelinating EAE in naive recipient mice. SJL/J mice with R-EAE induced by a PLP 139-151-specific T cell line expressing 88% V beta 2 were treated with anti-V beta 2 mAb. Anti-V beta 2 mAb markedly reduced clinical and histological disease severity when given at the time of cell transfer or when given at clinical disease onset. In contrast, anti-V beta mAbs showed only a mild clinical effect on R-EAE induced by immunization with PLP 139-151 or R-EAE transferred by a PLP 139-151-specific T cell line expressing multiple V beta s. A cocktail of mAbs directed against V beta 2, V beta 4, and V beta 17 significantly reduced the numbers of spinal cord T cells expressing these V beta s during acute EAE but had little effect on disease course, suggesting that pathogenic T cells expressing other V beta s were producing disease. These findings may have implications for the treatment of multiple sclerosis with V beta-selective therapy.

Limited heterogeneity of rearranged T cell receptor V alpha and V beta transcripts in synovial fluid T cells in early stages of rheumatoid arthritis

OBJECTIVE

The identification of activated T cells in synovial fluid and synovium, and the association of rheumatoid arthritis (RA) with specific HLA-DR restriction elements, strongly suggest that these T cells play a critical role in the etiology and pathogenesis of RA. Analysis of the T cell receptor (TCR) repertoire in the early stages of RA might be an approach to identify those T cells involved in the initiation and/or perpetuation of the disease.

METHODS

TCR V alpha and V beta transcripts of synovial T cells, sampled at the early stages of RA, were amplified by reverse transcriptase-polymerase chain reaction. HLA-DR subtyping was determined by serologic analysis and dot-blot hybridization of polymerase chain reaction amplification products using digoxigenin-labeled, sequence-specific oligonucleotide probes.

RESULTS

Our findings showed a limited heterogeneity of V alpha and V beta TCRs in synovial fluid T cells, and a preferential usage of TCR V alpha 17 in early RA. In contrast, in the later stages of RA, a more polyclonal TCR V alpha and V beta gene usage was observed.

CONCLUSION

Our results support the view that induction of RA is driven by an oligoclonal immune response to an unknown antigen. These findings also suggest a pathogenetic role for V alpha 17 T cells in the early stages of RA.

Staphylococcal enterotoxin B and tumor-necrosis factor-alpha-induced relapses of experimental allergic encephalomyelitis: protection by transforming growth factor-beta and interleukin-10

A study was made of the ability of the superantigen staphylococcal enterotoxin B (SEB) to induce relapses of experimental allergic encephalomyelitis (EAE) in SJL mice that had partially or completely recovered from acute EAE. We find that a single injection of 0.05 mg SEB i.v. induces mild relapses in 50% of such mice. In addition, tumor necrosis factor (TNF)-alpha (0.2 micrograms, i.p.) also induces EAE relapses in 43% of SJL mice when injected 1-2 months after recovery. SEB does not induce a second relapse if reinjected when V beta 17a+T cells are still partially deleted. In these mice, however, TNF-alpha is equally effective in inducing relapses as in mice that did not receive SEB previously. We showed earlier that transforming growth factor (TGF)-beta and TNF-alpha have antagonistic effects on experimental autoimmune diseases; e.g., in spontaneously relapsing EAE, TGF-beta and anti-TNF were protective, while anti-TGF-beta caused disease exacerbation. Interleukin (IL)-10 is also known to counteract certain TNF effects. We now find that both human IL-10 and TGF-beta 2 lower the incidence of EAE relapses when given simultaneously with SEB or TNF-alpha. The protective effect of TGF-beta is significant only against relapses induced by SEB (reduced to 9%), and that of IL-10 only against relapses induced by TNF (reduced to 0%) with the treatment regimens employed. Neutralizing anti-TGF-beta does not increase the incidence of SEB-induced EAE relapses. In contrast, anti-IL-10 increases both the incidence and the severity of such relapses. We conclude that TNF production is probably important in causing EAE relapses, but that other aspects of the SEB-induced reactivation of myelin-specific T cells also contribute. Furthermore, endogenous IL-10 rather than TGF-beta production appears to limit the susceptibility to induction of EAE relapses in this model.

A myelin oligodendrocyte glycoprotein peptide induces typical chronic experimental autoimmune encephalomyelitis in H-2b mice: fine specificity and T cell receptor V beta expression of encephalitogenic T cells

A predominant response to myelin oligodendrocyte glycoprotein (MOG) was recently observed in patients with multiple sclerosis (MS). To study the possible pathogenic role of T cell response to MOG in MS, we have investigated the encephalitogenic potential of MOG. Synthetic MOG peptides, pMOG 1-21, 35-55, 67-87, 104-117 and 202-218, representing predicted T cell epitopes, were injected into C57BL/6J and C3H.SW (H-2b) mice. The mice developed significant specific T cell responses to pMOG 1-21, pMOG 35-55 and pMOG 104-117. However, pMOG 35-55 was the only MOG peptide which could induce neurological impairment. The highly reproducible disease was chronic, with ascending paralysis and neuropathology comparable with those observed in experimental autoimmune encephalomyelitis (EAE) induced by myelin basic protein or proteolipid protein, except that in H-2b mice the disease was consistently non-remitting. These features differ markedly from those which we recently observed in PL (H-2u) mice with pMOG 35-55-induced disease. In PL mice, pMOG 35-55-induces atypical chronic relapsing EAE, the expression and progression of which are unpredictable. Hence, in different mouse strains, the same MOG peptide can induce typical EAE characterized by ascending paralysis, or atypical EAE with unpredictable clinical signs. pMOG 35-55-specific T cells from H-2b mice recognized an epitope within amino acids 40-55 of the MOG molecule, and pMOG 40-55-reactive T cell lines were encephalitogenic upon transfer into syngeneic recipients. The encephalitogenic pMOG 35-55-reactive C57BL/6J T cell lines expressed V beta 1, V beta 6, V beta 8, V beta 14 and V beta 15 gene segments, and the pMOG 35-55-reactive C3H.SW T cell lines expressed V beta 1, V beta 2, V beta 6, V beta 8, V beta 10, V beta 14, and V beta 15 gene segments. However, in both mouse strains, the utilization of the V beta 8 gene product was predominant (40-43%). The highly reproducible encephalitogenic activity of pMOG 35-55 strongly suggests a pathogenic role for T cell reactivity to MOG in MS and supports the possibility that MOG may also be a primary target antigen in the disease.

Critical influences of the cytokine orchestration on the outcome of myelin antigen-specific T-cell autoimmunity in experimental autoimmune encephalomyelitis and multiple sclerosis

In EAE/MS, effector molecules are produced as a result of the interaction between T lymphocytes and antigen-presenting cells and the spectrum of cytokines produced is likely to decisively influence the disease outcome. These events may be more important, or at least more easily accessible to therapeutic intervention, than particular autoantigen specificities. Data from EAE suggest that cytokines connected to the Th1 phenotype of lymphocytes, especially IFN-gamma but also TNF-beta, TNF-alpha and IL-12, may promote inflammation while cytokines connected to the Th2 subset, IL-4, IL-10 and TGF-beta, may potentially have a role in disease limitation. It will be important to accurately study cytokines during immunotherapeutic interventions and in relation to immunogenetic variables in order to aim at immunotherapeutically intervening in the Th1, Th2 balance as well as counteracting disease-promoting cytokines such as IFN-gamma and TNF-alpha or promoting the action of downregulatory cytokines such as IL-10 and TGF-beta.

Susceptibility to actively-induced murine experimental allergic encephalomyelitis is not linked to genes of the T cell receptor or CD3 complexes

The role of the T cell receptor (TCR) in the genetic control of susceptibility to autoimmune demyelinating diseases remains shrouded in controversy. We have used the CXD2 series of recombinant inbred lines (RIL) and a (B10.S/DvTe x SJL/J) x B10.S/DvTe backcross (BC1) population to test for linkage between susceptibility to actively-induced EAE and the different TCR and CD3 loci. The two populations were inoculated for induction of EAE, phenotyped for both clinical and histological parameters of disease, and genotyped using markers flanking the loci of interest in the CXD2 RIL and an SJL/J allele-specific TCR V beta assay in the BC1 mice. Comparisons between the CXD2 strain distribution pattern (SDP) for disease and the SDPs for the chromosomal regions containing the TCR alpha, beta, gamma, delta, and CD3 delta, epsilon, gamma and zeta loci showed no linkage to these loci. Additional tests between EAE susceptibility and several other immunologically important loci for which the SDPs were known also showed no linkage to the minor lymphocyte-stimulating antigen gene Mlsl, Hc, the gene encoding complement component C5, Cd8a, or Cd5. Furthermore, our data from the BC1 mice demonstrate that the Tcrb locus segregates independent of disease and does not modulate disease severity. We conclude that while autoreactive TCRs are undoubtedly necessary for disease pathogenesis, the principle non-MHC-linked loci controlling susceptibility to murine EAE in BALB/c mice are not linked to any of the individual TCR-CD3 complex genes. Similarly, the major disease genes in the SJL/J mouse are not linked to TCR V beta. Our data cannot, however, preclude the possibility that TCR/CD3 alleles are involved in epigenetic phenomena or susceptibility in other mouse strains or animal systems.

Determinant-regulated onset of experimental autoimmune encephalomyelitis: distinct epitopes of myelin proteolipid protein mediate either acute or delayed disease in SJL/J mice

In the present study we address the question of whether distinct self-determinants can target alternative autoimmune disease patterns in experimental autoimmune encephalomyelitis (EAE), an animal model widely used for studying multiple sclerosis. We have found that the clinical course of EAE can be determined by the target peptide selected for induction of disease. In SJL/J mice, actively induced and passively transferred EAE mediated by the immunodominant PLP determinants p139-151 and p178-191 consistently produced a rapid onset of severe clinical signs. In contrast, a delayed onset of both active and passive EAE is associated with the nondominant cryptic PLP determinant p104-117. The delayed disease induced with p104-117 is not associated with any unusual peptide feature, with bystander immunoregulation, with inept class II MHC binding, or with failure to induce T cell expression of CD44, VLA-4, or IL-2 receptor upon activation. However, delayed disease is associated with innate qualities of the T cell repertoire responding to the p104-117 determinant. T cell lines responding to the cryptic p104-117 show limited TCR-V beta utilization compared to the diverse repertoire responding to the dominant p139-151 determinant. The repertoire deletions are accompanied by low level production of pathogenic Th1 cytokines (IFN gamma; IL-2) and increased production of regulatory Th2 (IL-4) cytokine in activated p104-117 primed T cells. Thus, the delayed encephalitogenicity of p104-117 may be due to TCR-V beta deletions and activation defects in the responding T cell repertoire. The development of "slow disease" mediated by autoreactivity against hidden self-determinants may have important implications in the pathogenesis of both relapsing and chronic autoimmune demyelinating disease.

The role of the trimolecular complex (alpha beta TCR-MHC+peptide) in the pathogenesis of systemic sclerosis

Systemic sclerosis is an intricate disease process whose most unique and specific parameter indicative of autoimmunity is the presence of autoantibodies directed against certain nuclear antigens. The relationship between this particular humoral immune response and the genesis of a fibrotic tissue response in the skin as well as internal organs is not yet well understood. The prominence of CD4 T-cell infiltration during early phases of disease suggest that activation pathways may be initiated which subsequently result in phenotypic changes of a variety of mesenchymal cells, especially endothelial cells and fibroblasts. Taken in concert with the association of susceptibility with certain MHC class II molecules, the conventional presenters of exogenous peptide to T cells of the CD4 lineage, the notion of a central critical immune recognition event underlying the development of systemic sclerosis gains increasing likelihood. In addition to the still incompletely understood paracrine pathways between immune response and fibrosis, there is a nearly complete void of knowledge concerning what peptide is recognized by the T-cell and the structure of the alpha beta TCR involved in this recognition. Determining the role of the alpha beta TCR in the activation of the T-cell population in terms of identifying structural features which are critical participants in this process and the functional derangement leading to the characteristic pattern of self recognition will certainly enhance our understanding of the pathogenesis of systemic sclerosis.

Transfer of Sjögren's syndrome-like autoimmune lesions into SCID mice and prevention of lesions by anti-CD4 and anti-T cell receptor antibody treatment

We describe the successful transfer of murine Sjögren's syndrome-like autoimmune lesions from MRL/lpr mice (H-2k) to severe combined immunodeficiency (SCID) mice (H-2d) and prevention of lesions by anti-CD4 and -T cell receptor V beta 8 antibody treatment. Mononuclear cells (1 x 10(6)) isolated from the inflamed submandibular salivary gland tissues of MRL/lpr mice were transferred intraperitoneally into SCID mice. Autoimmune lesions resembling those seen in Sjögren's syndrome developed in the salivary and lacrimal glands of SCID mice 8 weeks after the injection, whereas other organs did not show any lesion. This pathology resembles Sjögren's syndrome in humans involving both the salivary and lacrimal glands. Immunohistochemically, a major proportion of these infiltrating cells in transferred SCID mice were CD4+ and V beta 8+. When the spleen cells from MRL/lpr mice were injected, severe inflammatory lesions, probably resulting from a graft-versus host reaction, were observed in multiple organs of SCID mice. The disease could not be induced by intraperitoneal administration of the sera from MRL/lpr mice, or of the spleen cells from C3H/He (H-2k) and BALB/c (H-2d) mice. We detected autoantibody production specific for the salivary gland tissue in sera from transferred SCID mice. Moreover, we found that the lesions were prevented by administration of the isolated cells treated in vitro with anti-CD4 and anti-V beta 8 monoclonal antibodies. These results suggest that CD4- and V beta 8-bearing T cells are involved in recognizing an autopeptide and triggering autoimmunity in the salivary and lacrimal glands, and therapies designed with anti-CD4 and anti-V beta 8 antibodies may prove effective in treating the murine autoimmune disease.

Pathogenesis of Sjögren's syndrome-like autoimmune lesions in MRL/lpr mice

Sjögren's syndrome in humans is a chronic inflammatory disease with a presumed autoimmune etiology of the exocrine organs, involving in particular the salivary and lacrimal glands. The pathogenesis of this syndrome remains unclear, but the majority of infiltrating cells in the salivary glands are CD4+ T cells both in humans and rodents. Since many cytokines are involved in the development of T cell-mediated autoimmunity, local cytokine gene expression was analyzed in vivo using an animal model for Sjögren's syndrome in MRL/lpr mice. Overexpression of interleukin-1 (IL-1)beta and tumour necrosis factor (TNF) was detected before the onset of inflammatory lesions in the salivary gland, and the upregulation of IL-6 mRNA was also found in accordance with autoimmune sialadenitis in MRL/lpr mice. The inflammatory cytokines such as IL-1 beta, TNF, and IL-6 have proved to play important roles as regulatory proteins inducing autoimmune phenomena. In addition, the expression of T cell antigen receptor beta (TCR) beta transcripts in the salivary gland tissues was analyzed. Transcript for V beta 8 was predominantly detected in the T cells infiltrating sialadenitis from the onset of the disease, suggesting that CD4+ T cells bearing TCR V beta 8 play an essential role in recognizing unknown autopeptide in the autoimmune sialadenitis of MRL/lpr mice. Furthermore, Sjögren's syndrome-like autoimmune lesions were successfully transferred into severe combined immunodeficiency (SCID) mice, and these lesions were prevented by administration of anti-CD4, and anti-V beta 8 monoclonal antibodies. This article will review recent observations of these pathogenetic analyses of autoimmune sialadenitis as it occurs in MRL/lpr mice.

Minireview: autoimmune responses to myelin proteolipid protein

The authors present a brief historical sketch of the development of our understanding of immune responses to myelin proteolipid protein (PLP) and the acceptance of PLP as a potent antigen in the induction of experimental allergic encephalomyelitis (EAE). The distinct characteristics of the PLP molecule that may contribute to complex immune responses to this protein are reviewed and these responses are compared with those to MBP, both in the pathology of EAE and at the level of the T cell. Recent evidence demonstrating differences between T cell responses to PLP and MBP is reviewed. Finally, the potential contribution of immune responses to PLP in human diseases, particularly multiple sclerosis (MS), that have been identified to date are then summarized.

Characterization of brain-isolated rat encephalitogenic T cell lines

In the present study, we have isolated and characterized five myelin basic protein (MBP)-reactive T cell lines directly from the brains of Lewis rats during the early paralytic phase of experimental autoimmune encephalomyelitis (EAE). Each T cell line responded to the dominant encephalitogenic epitope spanning residues 68-88, and did not react against the conserved encephalitogenic epitope [MBP(87-99)] or the nonencephalitogenic MBP epitope [MBP(50-69)]. We determined the T cell receptor (TcR) beta chain usage by polymerase chain reaction, DNA sequencing analysis and by generation of MBP-reactive hybridomas from one of the T cell lines (BT74). The results revealed that brain-infiltrating, MBP-reactive T cells freshly isolated early in the course of the disease exhibit TcR diversity.

T cell receptor (TCR) usage determines disease susceptibility in experimental autoimmune encephalomyelitis: studies with TCR V beta 8.2 transgenic mice

Experimental allergic encephalomyelitis (EAE) is an autoimmune disease that can be induced in laboratory animals by immunization with the major myelin proteins, myelin basic protein (MBP) and proteolipid protein (PLP). We analyzed the role of the T cell receptor (TCR) repertoire in susceptibility to EAE induced by these two autoantigens. Autoreactive T cells induced after immunization with MBP use a limited set of TCR. In contrast, we demonstrate that T cell clones that recognize the encephalitogenic PLP epitope (PLP 139-151) use diverse TCR genes. When the TCR repertoire is limited by introduction of a novel rearranged TCR V beta 8.2 chain in transgenic SJL mice, EAE could be induced in the transgenic mice by immunization with the encephalitogenic epitopes of PLP, but not with the encephalitogenic epitope of MBP. Thus, skewing the TCR repertoire affects the susceptibility to EAE by immunization with MBP but not with PLP. These data demonstrate the biological consequences of the usage of a more diverse T cell repertoire in the development of an autoimmune disease.

Encephalitogenicity of myelin basic protein exon-2 peptide in mice

Immunization with a synthetic peptide with an amino acid sequence corresponding to mouse myelin basic protein exon-2 induced mild experimental allergic encephalitis (EAE) in B10.RIII mice, very mild disease in SJL/J mice and no disease in (SJL x PL)F1 hybrid mice. In contrast, adoptive transfer of an exon-2 peptide-specific T cell line from SJL mice induced severe relapsing EAE in syngeneic recipients. The T cell line was specific for exon-2 peptide and did not cross-react appreciably with an MBP preparation consisting of the 18.5 and 14-kDa isoforms. mRNA for exon-2 containing isoforms could be demonstrated in the spinal cord of SJL/J and B10.RIII mice by amplification using exon-2 and exon-4 oligonucleotide primers. On a relative basis, the level of exon-2 cDNA was lower than that of exon-1 cDNA in the same spinal cord preparations from both strains of mice.

Diversity of endogenous epitopes bound to MHC class II molecules limited by invariant chain

The invariant chain (Ii) binds nascent major histocompatibility complex (MHC) class II molecules, blocking peptide binding until the complex dissociates in the endosomes. This may serve to differentiate the MHC class I and II antigen presentation pathways and enable class II molecules to efficiently bind peptides in the endosomes. This hypothesis was addressed by probing spleen cells from a combination of knock-out and transgenic mice with a large panel of T cell hybridomas. The Ii molecule blocked the presentation of a range of endogenously synthesized epitopes, but some epitopes actually required Ii. Thus, the influence of Ii on presentation does not follow simple rules. In addition, mice expressing Ii were not tolerant to epitopes unmasked in its absence, a finding with possible implications for autoimmunity.

Animal models

Different models of experimental autoimmune encephalomyelitis (EAE) have been successfully applied to investigate and manifold aspects of the autoimmune pathogenesis of multiple sclerosis. Studies using myelin-specific T-cell lines that transfer EAE to naive recipient animals established that only activated lymphocytes are able to cross the endothelial blood-brain barrier and cause autoimmune disease within the local parenchyma. All encephalitogenic T cells are CD4+ Th1-type lymphocytes that recognize autoantigenic peptides in the context of MHC class II molecules. In the case of myelin basic protein (MBP) specific EAE in the Lewis rat, the T-cell response is directed against one strongly dominant peptide epitope. The encephalitogenic T cells preferentially use one particular set of T-cell receptor genes. Although MBP is a strong encephalitogen in many species, a number of other brain protein are now known to induce EAE. These include mainly myelin components (PLP, MAG, and MOG), but also, the astroglial S-100 beta protein. Encephalitogenic T cells produce only inflammatory changes in the central nervous system, without extensive primary demyelination. Destruction of myelin and oligodendrocytes in these models requires additional effector mechanisms such as auto-antibodies binding to myelin surface antigens such as the myelin-oligodendrocyte glycoprotein.