Relapsing Experimental Allergic Encephalomyelitis Research Articles

CNS myeloid DCs presenting endogenous myelin peptides 'preferentially' polarize CD4+ TH-17 cells in relapsing EAE

Peripherally derived CD11b(+) myeloid dendritic cells (mDCs), plasmacytoid DCs, CD8alpha(+) DCs and macrophages accumulate in the central nervous system during relapsing experimental autoimmune encephalomyelitis (EAE). During acute relapsing EAE induced by a proteolipid protein peptide of amino acids 178-191, transgenic T cells (139TCR cells) specific for the relapse epitope consisting of proteolipid protein peptide amino acids 139-151 clustered with mDCs in the central nervous system, were activated and differentiated into T helper cells producing interleukin 17 (T(H)-17 cells). CNS mDCs presented endogenously acquired peptide, driving the proliferation of and production of interleukin 17 by naive 139TCR cells in vitro and in vivo. The mDCs uniquely biased T(H)-17 and not T(H)1 differentiation, correlating with their enhanced expression of transforming growth factor-beta1 and interleukins 6 and 23. Plasmacytoid DCs and CD8alpha(+) DCs were superior to macrophages but were much less efficient than mDCs in presenting endogenous peptide to induce T(H)-17 cells. Our findings indicate a critical function for CNS mDCs in driving relapses in relapsing EAE.

Downregulation of Transforming Growth Factor-β2 Facilitates Inflammation in the Central Nervous System by Reciprocal Astrocyte/Microglia Interactions

The central nervous system is an immune privileged organ in which inflammatory reactions are normally downregulated by mechanisms that are not completely understood. Transforming growth factor (TGF)-beta2 is constitutively expressed in the adult central nervous system and little is known about its regulation and modulatory role during neuroinflammation. In this study, we show that TGFbeta2 mRNA and protein are downregulated in the acute phase of chronic relapsing experimental autoimmune encephalomyelitis, whereas the homologous cytokine TGFbeta1 is upregulated. To further characterize regulatory mechanisms, we resorted to an in vitro glial cell culture system. The proinflammatory cytokines IFNgamma and TNFalpha suppressed TGFbeta2 secretion by astrocytes, the major intracerebral producers of TGFbeta2. On the cellular level, activated microglia inhibited TGFbeta2 secretion but induced TGFbeta1 through soluble factors. On the other hand, TGFbeta2 influenced antigen-presenting cell functions of microglia by downregulating major histocompatibility complex class II expression and costimulatory/adhesion molecules, and thereby inhibited myelin basic protein-specific T cell proliferation. These data suggest that TGFbeta2 plays a central role in maintenance of the immune privilege of the central nervous system. Downregulation of astrocytic TGFbeta2 by T cell- and microglia-secreted cytokines appears to be a critical step in providing the grounds for acute and chronic neuroinflammation.

Ingested (oral) SIRS peptide 1–21 inhibits acute EAE by inducing Th 2-like cytokines

Objective Ingested type I IFN inhibits clinical attacks, relapses and inflammation in murine chronic relapsing EAE by inhibiting Th 1-like cytokines. Type I IFN activates human suppressor T cells that produce SIRS. Methods We examined whether oral (ingested) SIRS peptide inhibits EAE by decreasing Th 1-like cytokines. Results Parenteral SIRS peptide 1–21 showed a significant inhibition of disease severity in murine EAE. Ingested SIRS peptide at 10 and 100 μg SIRS peptide showed a significant inhibition of disease severity but also a prolonged delay in the onset of disease compared to placebo. There were significantly less inflammatory foci in the SIRS peptide fed group compared to the control mock fed group. Splenocytes from SIRS peptide 1–21 fed mice showed increased production of Th 2-like CD30L, IL-13, TCA-3 cytokines/chemokines and decreased production of Th 1-like cytokine lymphotactin. Interpretation Ingested (oral) SIRS peptide significantly inhibits both clinical EAE and inflammation predominately via counter-regulatory type 2-like cytokines/chemokines IL-13, CD30L and TCA-3.

Osteopontin-induced relapse and progression of autoimmune brain disease through enhanced survival of activated T cells

Relapses and disease exacerbations are vexing features of multiple sclerosis. Osteopontin (Opn), which is expressed in multiple sclerosis lesions, is increased in patients' plasma during relapses. Here, in models of multiple sclerosis including relapsing, progressive and multifocal experimental autoimmune encephalomyelitis (EAE), Opn triggered recurrent relapses, promoted worsening paralysis and induced neurological deficits, including optic neuritis. Increased inflammation followed Opn administration, whereas its absence resulted in more cell death of brain-infiltrating lymphocytes. Opn promoted the survival of activated T cells by inhibiting the transcription factor Foxo3a, by activating the transcription factor NF-kappaB through induction of phosphorylation of the kinase IKKbeta and by altering expression of the proapoptotic proteins Bim, Bak and Bax. Those mechanisms collectively suppressed the death of myelin-reactive T cells, linking Opn to the relapses and insidious progression characterizing multiple sclerosis.

Multi-peptide coupled-cell tolerance ameliorates ongoing relapsing EAE associated with multiple pathogenic autoreactivities

The probability that epitope spreading occurs in multiple sclerosis (MS) and the fact that patients have been shown to respond to multiple myelin epitopes concurrently makes the use of peptide-specific tolerance therapies targeting single epitopes problematic. To attempt to overcome this limitation, we have employed cocktails of peptides in the ECDI coupled-APC tolerance system in mice to determine if T cell responses to multiple autoepitopes can be targeted simultaneously. Preventative tolerance induced with splenocytes coupled with a peptide cocktail of four distinct encephalitogenic epitopes (PLP 139–151, PLP 178–191, MBP 84–104, and MOG 92–106) inhibited initiation of active EAE induced with each individual peptide and by a mixture of the four peptides by preventing activation of autoreactive Th1 cells and subsequent infiltration of inflammatory cells into the CNS. Most relevant to treatment of clinical MS, therapeutic tolerance initiated by splenocytes coupled with the peptide cocktail administered at the peak of acute disease prevented clinical relapses due to epitope spreading and ameliorated a diverse disease induced with a mixture of the four peptides. Interestingly, therapeutic tolerance appeared to be mediated by a mechanism distinct from preventative tolerance, i.e. by significantly increasing the levels of production of the anti-inflammatory cytokines TGF-β and/or IL-10 in both the periphery and the CNS.

Epitope Specificity of Autoreactive T and B Cells Associated with Experimental Autoimmune Encephalomyelitis and Optic Neuritis Induced by Oligodendrocyte-Specific Protein in SJL/J Mice

The encephalitogenic potential of oligodendrocyte-specific protein (OSP) in mice, its specific localization in the intralamellar tight junctions in CNS myelin, and the detection of autoreactivity against OSP in multiple sclerosis (MS) strongly suggest the relevance of autoreactivity against OSP in the pathogenesis of MS. In this study, we have characterized the autoimmune T and B cells that are associated with clinicopathological manifestations of OSP-induced MS-like disease in mice by using recombinant soluble mouse OSP (smOSP) and synthetic overlapping peptides spanning smOSP. SJL/J mice immunized with smOSP developed chronic relapsing clinical experimental autoimmune encephalomyelitis accompanied with intense perivascular and parenchymal inflammatory infiltrates, widespread demyelination, axonal loss, and remarkable optic neuritis. The smOSP-primed lymph node cells reacted predominantly against OSP55-80 and to a lesser extent also to OSP22-46 and OSP179-207. Unexpectedly, in vitro selection with smOSP resulted in pathogenic smOSP-specific CD4+ T cells that reacted equally well against OSP55-80, OSP22-46, OSP45-66, and OSP179-207. Fine analysis of the anti-OSP autoimmunity revealed that the disease is primarily associated with CD4+ T cells directed against the major (OSP55-80) and the minor (OSP179-207) encephalitogenic regions that were further delineated, both in vitro and in vivo, to OSP55-66 and OSP194-207, respectively. In contrast, the OSP-induced Abs were predominantly directed against OSP22-46; these Abs were mostly of IgG1 isotype, but high levels of IgG2a and IgG2b and significant levels of IgE were also observed. The reactivity of pathogenic T cells to two encephalitogenic regions, OSP55-80 and OSP179-207, and their diverse TCRVbeta gene repertoire may impose difficulties for epitope-directed or TCR-targeting approaches to immune-specific modulation of OSP-related pathogenesis.

Gene-Based Intramuscular Interferon-β Therapy for Experimental Autoimmune Encephalomyelitis

In contrast to serial injections of recombinant interferon-β (IFN-β) for long-term therapy of multiple sclerosis (MS), prolonged systemic delivery of proteins derived through in vivo gene transfer may provide a more clinically relevant alternative. Here we compare the therapeutic efficacies of electroporation (EP)-mediated intramuscular IFN-β gene transfer with repeated alternate-day injections of recombinant IFN-β after the onset of relapsing–remitting experimental autoimmune encephalomyelitis (EAE), an animal model widely used in MS research. We show for the first time that a single EP-mediated intramuscular administration of 20 μg of an IFN-β-expressing plasmid provides long-term expression of interferon-inducible genes and is therapeutic in ongoing established EAE. The achieved therapeutic effects of IFN-β gene delivery were comparable to an 8-week regimen of 10,000 IU rIFN-β injected every other day and involved a significant inhibition of disease progression and a significant reduction of EAE relapses compared to untreated or null-vector-treated mice. Our results indicate the viability of a convenient and effective gene-based alternative for long-term IFN-β protein therapy in MS.

CD4+ T Cell Expressed CD80 Regulates Central Nervous System Effector Function and Survival during Experimental Autoimmune Encephalomyelitis

CD80 expressed on the surface of APCs provides a positive costimulatory signal to naive CD4+ T cells during activation. Therefore, it was hypothesized that treatment of SJL mice with various forms of anti-CD80 mAb during remission from the acute phase of relapsing experimental autoimmune encephalomyelitis (R-EAE) would ameliorate disease progression. We previously reported that treatment of SJL mice with anti-CD80 Fab during R-EAE remission blocked activation of T cells specific for endogenous myelin epitopes, inhibiting epitope spreading and clinical disease progression; however, treatment with the native form of the same anti-CD80 mAb exacerbated disease progression. The current data show that intact anti-CD80 mAb binds both CNS-infiltrating CD4+ T cells and CD11c+ dendritic cells and that exacerbation of R-EAE directly correlates with increased survival and activity of myelin-specific CD4+ T cells, while the percentage of CD11c+ dendritic cells in the CNS and their APC activity was not altered. In vitro data show that cross-linking CD80 on the surface of CD4+ T cells activated in the presence of Th1-promoting cytokines increases the level of T cell activation, effector function, and survival by directly up-regulating the expression levels of transcripts for T-bet, IFN-gamma, and Bcl-xL. These findings indicate a novel regulatory role for CD80-mediated intracellular signals in CD4+ T cells and have important implications for using anti-costimulatory molecule mAb therapy in established autoimmune disease.

Golli Protein Negatively Regulates Store Depletion-Induced Calcium Influx in T Cells

Calcium influx is crucial for T cell activation and differentiation. The detailed regulation of this process remains unclear. We report here that golli protein, an alternatively spliced product of the myelin basic protein gene, plays a critical role in regulating calcium influx in T cells. Golli-deficient T cells were hyperproliferative and showed enhanced calcium entry upon T cell receptor stimulation. We further found that golli regulates calcium influx in T cells through the inhibition of the store depletion-induced calcium influx. Mutation of the myristoylation site on golli disrupted its association with the plasma membrane and reversed its inhibitory action on Ca2+ influx, indicating that membrane association of golli was essential for its inhibitory action. These results indicate that golli functions in a unique way to regulate T cell activation through a mechanism involving the modulation of the calcium homeostasis.

Differential Role of Programmed Death-Ligand 1 and Programmed Death-Ligand 2 in Regulating the Susceptibility and Chronic Progression of Experimental Autoimmune Encephalomyelitis

Programmed death-1 (PD-1) is a negative costimulatory molecule, and blocking the interaction of PD-1 with its ligands, PD-L1 (B7-H1) and PD-L2 (B7-DC), enhances autoimmune disease in several animal models. We have studied the role of PD-1 ligands in disease susceptibility and chronic progression in experimental autoimmune encephalomyelitis (EAE). In BALB/c mice immunized with myelin oligodendrocyte glycoprotein (MOG) peptide 35-55, PD-L1 but not PD-L2 blockade significantly increased EAE incidence. In B10.S mice immunized with myelin proteolipid protein (PLP) peptide 139-151, both PD-L1 and PD-L2 blockade markedly enhanced EAE severity. In prediabetic NOD mice immunized with PLP48-70, PD-L2 blockade worsened EAE but did not induce diabetes, whereas PD-L1 blockade precipitated diabetes but did not worsen EAE, suggesting different regulatory roles of these two ligands in EAE and diabetes. B6 mice immunized with MOG35-55 developed chronic persistent EAE, and PD-L2 blockade in the chronic phase exacerbated EAE, whereas PD-L1 blockade did not. In contrast, SJL/J mice immunized with PLP139-151 developed chronic relapsing-remitting EAE, and only PD-L1 blockade during remission precipitated EAE relapse. The strain-specific effects of PD-1 ligand blockade did not correlate with the expression of PD-L1 and PD-L2 on dendritic cells and macrophages in lymphoid tissue, or on inflammatory cells in the CNS. However, EAE enhancement is correlated with less prominent Th2 cytokine induction after specific PD-1 ligand blockade. In conclusion, PD-L1 and PD-L2 differentially regulate the susceptibility and chronic progression of EAE in a strain-specific manner.

Analysis of lesion development during acute inflammation and remission in a rat model of experimental autoimmune encephalomyelitis by visualization of macrophage infiltration, demyelination and blood-brain barrier damage

In vivo tracking of macrophage migration is feasible by labeling cells with ultra-small particles of iron oxide (USPIO). It is demonstrated that it is possible to monitor distinct patterns of macrophage migration during the early states of inflammation in a rodent model of chronic relapsing experimental autoimmune encephalomyelitis (EAE). As previous MRI studies showed that EAE inflammation processes are clearly linked to macrophage infiltration in the brain, a longitudinal protocol for macrophage visualization was designed, where USPIOs were injected repeatedly during the acute phase of the disease, the remitting phase and the first relapse. In addition to USPIO-enhanced MRI, blood-brain barrier (BBB) damage, magnetization transfer ratios (MTRs) and neurological impairment were assessed as classical markers for central nervous system (CNS) inflammation and tissue damage. During the acute phase, animals showed severe paralysis of the hind paws, intense accumulation of macrophages in brain tissue and some diffuse patterns of BBB disruption. While USPIO-accumulation completely disappeared after the acute phase, residual damage of the BBB remained detectable in some lesions during the remitting phase. During the first relapse, the accumulation of USPIO-loaded cells was less pronounced but still detectable. The time course of MTR, which is used as a marker for myelin loss, was linked to the infiltration of macrophages during the acute phase.

CD25 regulatory T cells determine secondary but not primary remission in EAE: Impact on long-term disease progression

Multiple sclerosis (MS) is often characterized by several relapses and remissions during long-term disease, but neither the responsible cells nor the mechanisms are known to date. Using an animal model of multiple sclerosis, relapsing experimental autoimmune encephalomyelitis (R-EAE) CD4 +CD25 + T reg cells expressing Foxp3 and CTLA-4 intracellularly and T lymphocytes expressing surface CTLA-4 were identified in the CNS. The first remission occurred even after depletion of T reg cells, but secondary remissions from EAE were ablated. Despite the unaltered first remission autoantigen rechallenge revealed already an amplified cytokine response during acute phase. These results indicate that the cellular composition during first attack of MS predicts long-term disease progression.

Increased levels of bioactive IL-16 correlate with disease activity during relapsing experimental autoimmune encephalomyelitis (EAE)

Experimental autoimmune encephalomyelitis (EAE) is a CD4+ T-cell mediated disease, which resembles immunopathology of multiple sclerosis (MS). Interleukin (IL)-16 is a CD4+ cell-specific chemoattractant cytokine. In CD4+ T cells, production of bioactive IL-16 from constitutive pro-IL-16 requires cleavage by active caspase-3. We reported reversal of established relapsing disease by IL-16 neutralization. To better understand role(s) of IL-16 in regulation of relapsing EAE, we comparatively analyzed levels of IL-16, active caspase-3 and CD4 in mice with severe relapsing-remitting [(B6 × SJL) F1], and low-relapsing (B6), disease. Elevated levels of IL-16 along with an increase in active-caspase-3 and CD4 levels correlated with stages of clinically active disease in both strains. CNS levels of bioactive IL-16 were notably higher in F1 compared to B6 mice at all stages, being most prominent during relapse. Similar patterns of regulation for IL-16 and active caspase-3 were observed in peripheral lymphoid organs, and in T cells isolated from lymph nodes following T-cell activation in vitro. IL-16 was co-immunoprecipitated with CD4 from CNS of relapsing mice. Our data suggest that caspase-3 mediated production of IL-16 by infiltrating CD4+ T cells, contributes to ongoing neuroinflammation by chemoattraction of additional waves of CD4+ T cells.

A Suppressive Oligodeoxynucleotide Enhances the Efficacy of Myelin Cocktail/IL-4-Tolerizing DNA Vaccination and Treats Autoimmune Disease

Targeting pathogenic T cells with Ag-specific tolerizing DNA vaccines encoding autoantigens is a powerful and feasible therapeutic strategy for Th1-mediated autoimmune diseases. However, plasmid DNA contains abundant unmethylated CpG motifs, which induce a strong Th1 immune response. We describe here a novel approach to counteract this undesired side effect of plasmid DNA used for vaccination in Th1-mediated autoimmune diseases. In chronic relapsing experimental autoimmune encephalomyelitis (EAE), combining a myelin cocktail plus IL-4-tolerizing DNA vaccine with a suppressive GpG oligodeoxynucleotide (GpG-ODN) induced a shift of the autoreactive T cell response toward a protective Th2 cytokine pattern. Myelin microarrays demonstrate that tolerizing DNA vaccination plus GpG-ODN further decreased anti-myelin autoantibody epitope spreading and shifted the autoreactive B cell response to a protective IgG1 isotype. Moreover, the addition of GpG-ODN to tolerizing DNA vaccination therapy effectively reduced overall mean disease severity in both the chronic relapsing EAE and chronic progressive EAE mouse models. In conclusion, suppressive GpG-ODN effectively counteracted the undesired CpG-induced inflammatory effect of a tolerizing DNA vaccine in a Th1-mediated autoimmune disease by skewing both the autoaggressive T cell and B cell responses toward a protective Th2 phenotype. These results demonstrate that suppressive GpG-ODN is a simple and highly effective novel therapeutic adjuvant that will boost the efficacy of Ag-specific tolerizing DNA vaccines used for treating Th1-mediated autoimmune diseases.

Characterization of relapsing autoimmune encephalomyelitis and its treatment with decoy chemokine receptor genes

To elucidate the pathomechanisms of relapses of autoimmune disorders and to develop immunotherapy against relapses, we induced acute monophasic and chronic relapsing (CR) experimental autoimmune encephalomyelitis (EAE) in DA rats. Immunopathological and cytokine–chemokine analyses demonstrated that the number of infiltrating macrophages was significantly elevated in the CR-EAE than in acute EAE lesions and that IFN-γ and IP-10 in the spinal cord were significantly upregulated during the first attack and relapse of CR-EAE, respectively, than at the peak of acute EAE. In vivo administration of decoy chemokine receptor plasmid DNAs encoding the binding sites of CXCR3 and CCR2 suppressed the development of relapse of CR-EAE. Importantly, multiple injections of DNAs did not elicit the antibody production against chemokine receptors. Taken together, these findings demonstrated that neutralization therapy with decoy chemokine receptor DNAs is effective to control autoimmune diseases.

UCM707, an inhibitor of the anandamide uptake, behaves as a symptom control agent in models of Huntington's disease and multiple sclerosis, but fails to delay/arrest the progression of different motor-related disorders

To date, UCM707, (5Z,8Z,11Z,14Z)-N-(3-furylmethyl)eicosa-5,8,11,14-tetraenamide, has the highest potency and selectivity in vitro and in vivo as inhibitor of the endocannabinoid uptake. This may enable this compound to potentiate endocannabinoid transmission, with minimal side effects, in the treatment of several neurological disorders. In the present study, we examined whether the treatment with UCM707 produced beneficial effects, as other cannabinoid-related compounds have already shown, to alleviate motor deterioration or to delay/arrest neurodegeneration, in several models of neurological diseases such as Huntington's disease (HD), Parkinson's disease (PD) and multiple sclerosis (MS). UCM707 exhibited a notable anti-hyperkinetic activity in a rat model of HD generated by bilateral intrastriatal application of 3-nitropropionic acid. This effect was possibly associated with an amelioration of GABA and glutamate deficits induced by the toxin in the globus pallidus and the substantia nigra, respectively. However, UCM707 did not protect against the death of GABAergic neurons that occurs in rats with striatal atrophy generated by unilateral application of malonate, another animal model of HD, which is more useful to test neuroprotective strategies. In addition, UCM707 did not provide neuroprotection in rats with unilateral lesions of the nigrostriatal dopaminergic neurons caused by 6-hydroxydopamine, a rat model of PD. This was possibly due to the fact that UCM707 is devoid of anti-oxidant properties since another uptake inhibitor, AM404, that has these properties acted as a protective agent. Lastly, UCM707 was also unable to inhibit the development of the neurological impairment of rats with experimental autoimmune encephalomyelitis (EAE), an acute model of MS. However, UCM707, like other endocannabinoid uptake inhibitors reported previously, significantly reduced spasticity of the hindlimbs in a chronic relapsing EAE mice, a chronic model of MS. In summary, UCM707 might be a promising compound in HD to alleviate motor symptoms, which represents an important goal considering the current lack of efficient pharmacological treatments in this basal ganglia disorder. However, the compound was unable to delay neurodegeneration in this disorder and also in PD. In addition, UCM707 did not produce any neurological recovery from inflammatory attack in an EAE rat model of MS, although it retained the classic anti-spastic action shown by other uptake inhibitors in the EAE mouse model of this disease.

Leptin increase in multiple sclerosis associates with reduced number of CD4(+)CD25+ regulatory T cells.

We analyzed the serum and cerebrospinal fluid (CSF) leptin secretion and the interaction between serum leptin and CD4(+)CD25+ regulatory T cells (T(Regs)) in naive-to-therapy relapsing-remitting multiple sclerosis (RRMS) patients. Leptin production was significantly increased in both serum and CSF of RRMS patients and correlated with IFN-gamma secretion in the CSF. T cell lines against human myelin basic protein (hMBP) produced immunoreactive leptin and up-regulated the expression of the leptin receptor (ObR) after activation with hMBP. Treatment with either anti-leptin or anti-leptin-receptor neutralizing antibodies inhibited in vitro proliferation in response to hMBP. Interestingly, in the RRMS patients, an inverse correlation between serum leptin and percentage of circulating T(Regs) was also observed. To better analyze the finding, we enumerated T(Regs) in leptin-deficient (ob/ob) and leptin-receptor-deficient (db/db) mice and observed the significant increase in T(Regs). Moreover, treatment of WT mice with soluble ObR fusion protein (ObR:Fc) increased the percentage of T(Regs) and ameliorated the clinical course and progression of disease in proteolipid protein peptide (PLP(139-151))-induced relapsing-experimental autoimmune encephalomyelitis (R-EAE), an animal model of RRMS. These findings show an inverse relationship between leptin secretion and the frequency of T(Regs) in RRMS and may have implications for the pathogenesis of and therapy for multiple sclerosis.

New Approach to Immunotherapy Against Organ-specific Autoimmune Diseases with T Cell Receptor and Chemokine Receptor DNA Vaccines

Organ-specific autoimmune diseases are characterized by the presence of relapse and remittance of the clinical signs, and last for a long period of time in most cases without an appropriate treatment. Immunopathologically, T cells that respond to organ-specific autoantigens play an important role in the development of inflammatory lesions in the target organ. These pathogenic T cells that had been activated by various stimuli including preceding infection infiltrate the target organ in an antigen-specific manner and break the homeostasis of the organ. Furthermore, they secrete a large number of pro-inflammatory cytokines and chemokines, which recruit by-stander inflammatory cells in the lesion. Although general immunosuppressive drugs such as corticosteroid and cyclosporine are effective in suppressing clinical signs and inflammation, immunospecific therapy is essential for the establishment of long-lasting remission or complete cure. In order to achieve effective immunospecific therapy, several groups have focused on two key molecules that are deeply involved in pathogenesis of autoimmune diseases. One is the T cell receptor (TCR) expressed on pathogenic T cells and the other is the cytokine and chemokine receptor expressed in the target organ. Another important aspect of this issue is the reagent that is used for the suppression of the function of the key molecules. So far, monoclonal antibodies, peptide vaccines and DNA vaccines are the major reagents used for immunosuppressive therapies. In the present review, I introduce the results of immunotherapy obtained in my laboratory using TCR-based and chemokine receptor (chemoR)-based DNA in experimental autoimmune encephalomyelitis (EAE) and myocarditis (EAC) and discuss its effectiveness and pathomechanisms of immunosuppression. First, we administered DNA vaccines encoding pathogenic TCR Vbeta8.2, 10 (to Lewis rats) and 15 (to DA rats) and observed that these vaccinations protected animals from the development of EAE. Similar results were obtained in EAC. Second, DNAs encoding several chemoRs were prepared and administered after the challenge to neutralize the function of chemokines that are highly upregulated in the lesions. It was demonstrated that these chemoR DNAs suppress the relapse of chronic relapsing EAE and block the progression of EAC to dilated cardiomyopathy (manuscripts submitted for publication). These findings clearly indicate that DNA vaccination can be a powerful tool for treatment of organ-specific autoimmune diseases.

Epitope spreading initiates in the CNS in two mouse models of multiple sclerosis

Chronic progression of two T cell-mediated central nervous system (CNS) demyelinating models of multiple sclerosis, relapsing EAE (R-EAE) and Theiler's murine encephalomyelitis virus-induced demyelinating disease (TMEV-IDD) is dependent on the activation of T cells to endogenous myelin epitopes (epitope spreading). Using transfer of carboxyfluorescein succinyl ester (CFSE)-labeled T-cell receptor (TCR)-transgenic T cells and mixed bone marrow chimeras, we show that activation of naive proteolipid protein (PLP)139-151-specific T cells in SJL mice undergoing PLP178-191-induced R-EAE or TMEV-IDD occurs directly in the CNS and not in the cervical lymph nodes or other peripheral lymphoid organs. Examination of the antigen-presentation capacity of antigen-presenting cell (APC) populations purified from the CNS of mice with PLP178-191-induced R-EAE shows that only F4/80-CD11c+CD45hi dendritic cells (DCs) efficiently present endogenous antigen to activate naive PLP139-151-specific T cells in vitro. In contrast, DCs as well as F4/80+CD45hi macrophages and F4/80+CD45lo microglia activate a PLP139-151-specific helper T cell line. The data suggest that naive T cells enter the inflamed CNS and are activated by local APCs, possibly DCs, to initiate epitope spreading.

Anti‐IL‐16 therapy reduces CD4+ T‐cell infiltration and improves paralysis and histopathology of relapsing EAE

Infiltration of the central nervous system (CNS) by CD4+ Th1 cells precedes onset and relapses of experimental autoimmune encephalomyelitis (EAE). We reported that (B6xSJL) F1 (H-2b/s) mice with severe relapsing-remitting disease had extensive infiltration by CD4+ T cells compared to that in C57BL/6 (B6) (H-2b) mice, which developed mild low-relapsing disease in response to myelin oligodendrocyte peptide 35-55 (MOG(35-55)). This observation led us to search for mechanisms that specifically regulate trafficking of CD4+ cells in relapsing H-2b/s mice. We show that the CD4+ cell chemoattractant cytokine interleukin (IL)-16 has an important role in regulation of relapsing EAE induced by MOG(35-55) in the (B6xSJL) F1 (H-2b/s) mice. We found production of IL-16 in the CNS of mice with EAE. IL-16 levels in the CNS correlated well with the extent of CD4+ T-cell and B-cell infiltration during acute and relapsing disease. Infiltrating CD4+ T cells, B cells, and to a lesser extent CD8+ T cells all contained IL-16 immunoreactivity. Treatment with neutralizing anti-IL-16 antibody successfully reversed paralysis and ameliorated relapsing disease. In treated mice, diminished infiltration by CD4+ T cells, less demyelination, and more sparing of axons was observed. Taken together, our results show an important role for IL-16 in regulation of relapsing EAE. We describe a novel therapeutic approach to specifically impede CD4+ T cell chemoattraction in EAE based on IL-16 neutralization. Our findings have high relevance for the development of new therapies for relapsing EAE and potentially MS.