Clinical Experimental Allergic Encephalomyelitis Research Articles

Multiple linked quantitative trait loci within the Tmevd2/Eae3 interval control the severity of experimental allergic encephalomyelitis in DBA/2J mice

Theiler’s murine encephalomyelitis virus-induced demyelination (TMEVD) and experimental allergic encephalomyelitis (EAE) are the principal animal models of multiple sclerosis (MS). Previously we provided evidence that Tmevd2 and Eae3 may represent either a shared susceptibility locus or members of a gene complex controlling susceptibility to CNS inflammatory demyelinating disease. To explore the genetic relationship between Tmevd2 and Eae3, we generated a D2.C-Tmevd2 interval-specific congenic (ISC) line and three overlapping interval-specific recombinant congenic (ISRC) lines in which the Tmevd2 resistant allele from BALB/cByJ was introgressed onto the TMEVD-susceptible DBA/2J background. These mice, all H2d, were studied for susceptibility to EAE elicited by immunization with PLP180–199. Compared to DBA/2J mice, D2.C-Tmevd2 mice developed a significantly less severe clinical disease course and EAE pathology in the spinal cord, confirming the existence of Eae3 and its linkage to Tmevd2 in this strain combination. Compare to DBA/2J and D2.C-Tmevd2, all three ISRC lines exhibited clinical disease courses of intermediate severity. Neither differences in ex vivo antigen-specific cytokine nor proliferative responses uniquely cosegregated with differences in disease severity. These results indicate that multiple QTL within the Tmevd2/Eae3 interval influence EAE severity, one of which includes a homology region for a QTL found in MS by admixture mapping.

Physiological abnormalities in experimental allergic encephalomyelitis (EAE): II. Correlation between clinical signs and vestibular hyperreactivity and other signs of brain-stem dysfunction in rats with EAE.

12 Lewis rats were inoculated with a guinea pig spinal cord tissue preparation. They developed experimental allergic encephalomyelitis (EAE) after 12-14 days manifested by weight loss, tail flaccidity, ataxia, hind limb paresis or paralysis and urinary incontinence. Concomitantly with EAE, all animals developed vestibular hyperreactivity (VH) of canal and otolith reflexes. Other signs of brain-stem dysfunction were also observed: abducens paralysis, facial weakness, tachypnoe and mydriasis with defective pupillary light reflex. The vestibular and other abnormalities subsided with some delay after recovery from clinical EAE, whilst histological abnormalities were still present in the CNS.

Suppression of ongoing experimental allergic encephalomyelitis in DA rats by novel peptide drug, structural part of human myelin basic protein 46–62

Previously, we demonstrated that autoantibodies (AAb) in multiple sclerosis (MS) reveal site-specific binding and cleavage toward myelin basic protein (MBP) epitope library. We have found several fragments of MBP immunodominant in terms of AAb binding. Here, we applied these peptides to DA rats with induced protracted relapsing experimental allergic encephalomyelitis (EAE) most closely related to MS. DA rats with EAE induced by syngenic spinal cord homogenate in complete Freund's adjuvant were treated by nasal route with human MBP 46–62, 81–102, 124–139, 147–170, and Copaxone®. MBP 124–139 and 147–170 displayed only mild therapeutic effects but MBP 46–62 significantly reduced EAE, reflected by lower clinical scores and shorter EAE duration compared to controls.

Estrogen Receptor-1 (Esr1) and −2 (Esr2) Regulate the Severity of Clinical Experimental Allergic Encephalomyelitis in Male Mice

Estrogen Receptor-1 (Esr1) and −2 (Esr2) Regulate the Severity of Clinical Experimental Allergic Encephalomyelitis in Male Mice

Protein Kinase Cθ Controls Th1 Cells in Experimental Autoimmune Encephalomyelitis

Molecules that regulate encephalitogenic T cells are of interest for multiple sclerosis. In this study we show that protein kinase Ctheta (PKCtheta) is critical for the development of Ag-specific Th1 cells in experimental allergic encephalomyelitis (EAE), a model of multiple sclerosis. PKCtheta-deficient mice immunized with myelin oligodendrocyte glycoprotein failed to develop cell infiltrates and Th1 cytokines in the CNS and were resistant to the development of clinical EAE. CD4 T cells became primed and accumulated in secondary lymphoid organs in the absence of PKCtheta, but had severely diminished IFN-gamma, TNF, and IL-17 production. Increasing Ag exposure and inflammatory conditions failed to induce EAE in PKCtheta-deficient mice, showing a profound defect in the myelin oligodendrocyte glycoprotein-reactive T cell population. These data provide evidence of a pivotal role for PKCtheta in the generation and effector function of autoimmune Th1 cells.

Autoantigen-pulsed dendritic cells constitute a beneficial cytokine and growth factor network in ameliorating experimental allergic encephalomyelitis

Injection of myelin basic protein (MBP)-pulsed dendritic cells (DC) into healthy rats, as we reported before and observed in this study, did not induce clinical experimental allergic encephalomyelitis (EAE), but effectively protected the rats from subsequent EAE induction. The mechanisms by which MBP-pulsed DC mediate immune protection are not completely understood. In the present study, we mainly explored the dynamic change of cytokine and growth factor mRNA expression in spinal cords after subcutaneous injection of MBP-pulsed and unpulsed DC. The expression of interleukin (IL)-1, interferon-gamma and tumour necrosis factor-alpha as well as programmed death ligand (PDL)-1, PDL-2, signal transducer and activator of transcription (STAT)4, STAT6, matrix metalloproteinase (MMP)-9 and tissue inhibitor of metalloproteinases (TIMP)-2 was increased on day 0 postimmunization (p.i.). The increase of IL-12 expression was observed on day 7 p.i., while the increase of IL-10 expression mainly occurred on day 14 p.i. Except downregulation of insulin-like growth factor-1, the expression of brain-derived neurotrophic factor, ciliary neurotrophic factor, fibroblast growth factor (FGF)-2 and platelet-derived growth factor (PDGF)-B/C as well as nerve growth factor receptor (NGF-R), FGF receptor, PDGF-R-alpha and beta was elevated on day 0 p.i., while the increase of TIMP and NGF was observed on days 0 and 7 p.i. There were no significant differences on MMP-2, spinal cord-derived growth factor and PDGF-A mRNA expression. In line with the suppression of EAE induced by MBP-pulsed DC, the dynamic change of cytokines and growth factors in spinal cords should constitute a beneficial microenvironment against EAE.

Gender, Age, and Season at Immunization Uniquely Influence the Genetic Control of Susceptibility to Histopathological Lesions and Clinical Signs of Experimental Allergic Encephalomyelitis: Implications for the Genetics of Multiple Sclerosis

Multiple sclerosis (MS), the principal inflammatory demyelinating disease of the central nervous system (CNS), is believed to have an immunopathological etiology arising from gene-environment interactions. In this study, we examined the effect of sex, age, and season at immunization on the susceptibility of (B10.S x SJL/J) F(2) intercross mice to experimental allergic encephalomyelitis (EAE), the foremost animal model of MS. Results of logistic regression analyses suggest that female mice were more likely to exhibit CNS lesions than male mice [odds ratio (OR) = 2.28 for brain lesions; OR = 2.37 for spinal cord (SC) lesions]. Although statistically significant associations were seen between brain and SC lesions and age at the time of injection or month of injection when examined separately; these associations disappeared when controlling for sex in multiple logistic regression analyses. These results suggest that the sex of the mouse is more important in influencing the development of brain and SC lesions than was either age or month of immunization. When examining clinical disease as the endpoint, the OR for the age at immunization is 1.04, indicating that the odds of being affected increase by 4% for each increasing week of age. When controlled for age, the OR for injection in the summer months (July through September) is 1.90, suggesting that the odds of being clinically affected are 90% greater for F(2) intercross animals injected in the summercompared to those injected in the winter to spring months (February through May). In contrast to CNS lesions, the age and season at immunization significantly and independently influenced susceptibility to clinical EAE and did so equally in both males and females. Linkage analysis to eae5, the H2-linked locus controlling susceptibility to clinical disease, was performed using 6- to 12- and >12-week-old cohorts as well as summer and winter/spring cohorts of F(2) mice. Significant linkage of clinical EAE to eae5 was observed with the 6- to 12-week-old and summer populations. In contrast, linkage of clinical EAE to eae5 was not detected with the >12-week-old and winter/spring populations. These results indicate that age and seasonal effects are capable of overriding eae5-dependent genetic control of susceptibility to clinical EAE and have significant implications for the genetics of MS.

Estrogen Receptor-1 ( Esr1) and -2 ( Esr2) Regulate the Severity of Clinical Experimental Allergic Encephalomyelitis in Male Mice

Estrogens and estrogen-receptor signaling function in establishing and regulating the female immune system and it is becoming increasingly evident that they may play a similar role in males. We report that B10.PL/SnJ male mice with a disrupted estrogen receptor-1 (alpha) gene (Esr1(-/-)) develop less severe clinical experimental allergic encephalomyelitis (EAE) compared to either Esr1(+/-) or wild-type (Esr1(+/+)) controls when immunized with myelin basic protein peptide Ac1-11 (MBP(Ac1-11)). In contrast, the disease course in B10.PL/SnJ male mice with a disrupted estrogen receptor-2 (beta) gene (Esr2(-/-)) does not differ from that of wild-type (Esr2(+/+)) mice. However, Esr2(+/-) mice do develop more severe clinical disease with an earlier onset indicating that heterosis at Esr2 plays a significant role in regulating EAE in males. No significant differences in central nervous system histopathology or MBP(Ac1-11)-specific T-cell responses as assessed by proliferation and interleukin-2 production were observed as a function of either Esr1 or Esr2 genotype. An analysis of cytokine/chemokine secretion by MBP(Ac1-11)-specific T cells revealed unique Esr1 and Esr2 genotype-dependent regulation. Interferon-gamma secretion was found to be negatively regulated by Esr1 whereas interleukin-6 and tumor necrosis factor-alpha secretion exhibited classical Esr2 gene dose responses. Interestingly, MCP-1 displayed distinctively unique patterns of genotype-dependent regulation by Esr1 and Esr2. The contribution of the hematopoietic and nonhematopoietic cellular compartments associated with the heterotic effect at Esr2 in regulating the severity of clinical EAE was identified using reciprocal hematopoietic radiation bone marrow chimeras generated between male wild-type and Esr2(+/-) mice. Wild-type --> Esr2(+/-) mice exhibited EAE equivalent in severity to that seen in Esr2(+/-) --> Esr2(+/-) control constructs; both of which were more severe than the clinical signs observed in Esr2(+/-) --> wild-type and wild-type --> wild-type mice. These results indicate that the heterotic effect at Esr2 is a function of the nonhematopoietic compartment.

Antigenized antibodies expressing Vβ8.2 TCR peptides immunize against rat experimental allergic encephalomyelitis

BackgroundImmunity against the T cell receptor (TCR) is considered to play a central role in the regulation of experimental allergic encephalomyelitis (EAE), a model system of autoimmune disease characterized by a restricted usage of TCR genes. Methods of specific vaccination against the TCR of pathogenetic T cells have included attenuated T cells and synthetic peptides from the sequence of the TCR. These approaches have led to the concept that anti-idiotypic immunity against antigenic sites of the TCR, which are a key regulatory element in this disease.MethodsThe present study in the Lewis rat used a conventional idiotypic immunization based on antigenized antibodies expressing selected peptide sequences of the Vβ8.2 TCR (93ASSDSSNTE101 and 39DMGHGLRLIHYSYDVNSTEKG59).ResultsThe study demonstrates that vaccination with antigenized antibodies markedly attenuates, and in some instances, prevents clinical EAE induced with the encephalitogenic peptide 68GSLPQKSQRSQDENPVVHF88 in complete Freunds' adjuvant (CFA). Antigenized antibodies induced an anti-idiotypic response against the Vβ8.2 TCR, which was detected by ELISA and flowcytometry. No evidence was obtained of a T cell response against the corresponding Vβ8.2 TCR peptides.ConclusionsThe results indicate that antigenized antibodies expressing conformationally-constrained TCR peptides are a simple means to induce humoral anti-idiotypic immunity against the TCR and to vaccinate against EAE. The study also suggests the possibility to target idiotypic determinants of TCR borne on pathogenetic T cells to vaccinate against disease.

On the role of dendritic cells in peripheral T cell tolerance and modulation of autoimmunity.

Recently, it has become clear that dendritic cells (DCs) are essential for the priming of T cell responses. However, their role in the maintenance of peripheral T cell tolerance remains largely undefined. Herein, an antigen-presenting cell (APC) transfer system was devised and applied to experimental allergic encephalomyelitis (EAE), to evaluate the contribution that DCs play in peripheral T cell tolerance. The CD8α−CD4+ subset, a minor population among splenic DCs, was found to mediate both tolerance and bystander suppression against diverse T cell specificities. Aggregated (agg) Ig-myelin oligodendrocyte glycoprotein (MOG), an Ig chimera carrying the MOG 35–55 peptide, binds and cross-links FcγR on APC leading to efficient peptide presentation and interleukin (IL)-10 production. Furthermore, administration of agg Ig-MOG into diseased mice induces relief from clinical EAE involving multiple epitopes. Such recovery could not occur in FcγR-deficient mice where both uptake of Ig-MOG and IL-10 production are compromised. However, reconstitution of these mice with DC populations incorporating the CD8α−CD4+ subset restored Ig-MOG–mediated reversal of EAE. Transfer of CD8α+ or even CD8α−CD4− DCs had no effect on the disease. These findings strongly implicate DCs in peripheral tolerance and emphasize their functional potency, as a small population of DCs was able to support effective suppression of autoimmunity.

Autoantigen-pulsed dendritic cells induce tolerance to experimental allergic encephalomyelitis (EAE) in Lewis rats.

Dendritic cells (DC) can modulate the nature of immune responses in a stimulatory or tolerogenic fashion. Great attention has been given to the induction of immunity to tumour and infection. In this study, bone marrow-derived DC from healthy Lewis rats were pulsed in vitro with encephalitogenic myelin basic protein peptide 68-86 (MBP 68-86), and injected subcutaneously (1 x 106/rat) into normal Lewis rats. Upon observation of the rats pretreated in this way for 4 weeks, when no clinical signs of EAE occurred, these rats were immunized with MBP 68-86 and Freund's complete adjuvant. The pretreated rats failed to develop clinical EAE. This tolerance was associated with augmented proliferative responses, interferon-gamma secretion, inducible nitric oxide synthase (iNOS) expression and NO production. The frequency of apoptotic cells was increased in the rats receiving MBP 68-86-pulsed DC compared with unpulsed control DC. Few infiltrating inflammatory cells were observed in spinal cord sections from rats that had received MBP 68-86-pulsed DC. The data are compatible with the interpretation that MBP 68-86-pulsed DC induce tolerance to EAE possibly through up-regulation of iNOS expression and NO production, which mediate cell apoptosis, thereby reducing infiltration of inflammatory cells within the central nervous system.

Bone marrow-derived dendritic cells from experimental allergic encephalomyelitis induce immune tolerance to EAE in Lewis rats.

We have previously shown that dendritic cells (DC), upon being pulsed in vitro with encephalitogenic myelin basic protein peptide 68-86 (MBP 68-86) and injected subcutaneously (s.c.) back to healthy Lewis rats, transfer immune tolerance to experimental allergic encephalomyelitis (EAE) induced by immunization with MBP 68-86 and Freund's complete adjuvant (FCA). We here assumed that DC become pulsed in EAE rats, and that expansion in vitro of such 'in vivo pulsed EAE-DC' might also have the capacity to induce immune tolerance to EAE, thereby eliminating the need for in vitro pulsing of DC with autoantigens which are still unknown in many autoimmune diseases in the human. In the present study, EAE-DC were generated from bone marrow of Lewis rats, with EAE induced with MBP 68-86 + FCA, and expanded in vitro by culture with GM-CSF and IL-4. In comparison with DC from normal rats, EAE-DC exhibited higher viability in the absence of growth factors, and presented specific antigen to naïve T cells in vitro. The DC derived from both EAE and healthy rats stimulated strong proliferation in an antigen-independent manner, lasting for 4 weeks after DC were s.c. injected into healthy rats. During this time, injection of EAE-DC did not induce clinical EAE. However, when these rats were immunized with MBP 68-86 + FCA, subsequent EAE was dramatically suppressed, and was associated with increased IFN-gamma expression, nitric oxide production, gradually reduced proliferation and cell apoptosis, compared with PBS-injected control EAE rats. LPS-treated DC did not induce tolerance, suggesting that the tolerance is mediated by an immature stage of DC. These observations support the hypothesis that EAE-DC can transfer immune tolerance to EAE, thereby omitting the step of characterizing specific autoantigen. Omitting the step of loading DC with antigen not only eliminates the extremely complex procedure of defining pathogenically-relevant autoantigens, but also avoids the risk of inducing immunogenicity of DC in the treatment of autoimmune diseases.

Frequency, heterogeneity and encephalitogenicity of T cells specific for myelin oligodendrocyte glycoprotein in naive outbred primates.

Auto-reactive T cells present in healthy subjects remain in a state of unresponsiveness, but may trigger autoimmunity under various situations. Although myelin oligodendrocyte glycoprotein (MOG) is a potential target antigen in multiple sclerosis (MS), MOG-reactive T cell responses are present in the blood of both healthy subjects and MS-affected individuals. To investigate the disease-inducing potential and regulation of these autoreactive T cells in healthy outbred populations, we have characterized MOG-reactive T cell clones obtained by limiting dilution from peripheral blood of unimmunized C. jacchus marmosets. We report an extraordinarily high prevalence of circulating MOG-reactive T cells in these naive animals (2.6 +/- 1.4 / 10(5) PBMC), and a broadly diverse repertoire of epitope recognition encompassing at least three regions within the extracellular domain of MOG. Adoptive transfer of a MOG21-40-specific T cell clone resulted in mild clinical experimental allergic encephalomyelitis, characterized pathologically by rare foci of inflammation and minimal demyelination. We conclude that MOG-reactive T cells are present in healthy primates at a highly prevalent frequency, and are potentially capable of triggering central nervous system autoimmunity. Expansion of these autoreactive T cells must be tightly controlled to maintain immune homeostasis in healthy individuals.

Myelin/Axonal Pathology in Interleukin-12 Induced Serial Relapses of Experimental Allergic Encephalomyelitis in the Lewis Rat

Lewis rats, on recovery from monophasic clinical experimental allergic encephalomyelitis (EAE), can be induced to develop repeated paralytic relapses with a graded reduction in clinical severity following intraperitoneal administration of IL-12. By the time of the third relapse, the number and size of inflammatory cuffs in the spinal cord were reduced with the makeup of the cellular infiltrate shifting to a significantly increased number of B cells. Serum levels of myelin basic protein (MBP)-specific IgG1 and IgG2b were found to rise over time while MBP and MBP peptide-positive macrophages and microglia became evident in perivascular cuffs and in spinal cord parenchyma, indicative of myelin phagocytosis. Axonal death was observed in semithin and EM sections of spinal cord in third relapse animals in association with iNOS and tPA immunostaining throughout gray and white matter. These neurotoxic or excitotoxic agents may contribute to axonal damage directly or indirectly by activated microglia and macrophages, leading to limited damage of the axonal-myelin unit.

SIN-1, a nitric oxide donor, ameliorates experimental allergic encephalomyelitis in Lewis rats in the incipient phase: the importance of the time window.

NO is involved in the regulation of immune responses. The role of NO in the pathogenesis of experimental allergic encephalomyelitis (EAE) is controversial. In this study, 3-morpholinosydnonimine (SIN-1), an NO donor, was administered to Lewis rats on days 5-7 postimmunization, i.e., during the incipient phase of EAE. SIN-1 reduced clinical signs of EAE compared with those in PBS-treated control rats and was accompanied by reduced ED1(+) macrophages and CD4(+) T cell infiltration within the CNS. Blood mononuclear cells (MNC) obtained on day 14 postimmunization revealed that SIN-1 administration enhanced NO and IFN-gamma production by blood MNC and suppressed Ag- and mitogen-induced proliferative responses. MHC class II, B7-1 and B7-2 were down-regulated in SIN-1-treated EAE rats. Simultaneously, frequencies of apoptotic cells among blood MNC were increased. In vivo, SIN-1 is likely to behave as an NO donor. Administration of SIN-1 induced NO production, but did not affect superoxide and peroxynitrite formation. Enhanced NO production during the priming phase of EAE thus promotes apoptosis, down-regulates disease-promoting immune reactivities, and ameliorates clinical EAE, mainly through SIN-1-derived NO, without depending on NO synthase.

Essential role of TGF-β in the natural resistance to experimental allergic encephalomyelitis in rats

Experimental allergic encephalomyelitis (EAE) is a T cell-mediated autoimmune disease induced in susceptible rat strains by a single immunization with myelin basic protein (MBP). The Lewis (LEW) strain is susceptible to disease induction while the Brown Norway (BN) strain is resistant. This resistance involves non-MHC genes since congenic BN-1L rats, with LEW MHC on a BN-derived background, are also resistant. In the present study we show that, upon immunization with MBP, the non-MHC-encoded resistance to develop clinical EAE in BN-1L rats is associated with a decreased production of IFN-gamma. This may be due to a difference between LEW and BN-1L rats in their ability to produce regulatory cytokines such as IL-4, IL-10 and TGF-beta. In comparison to LEW rats, immune lymph node cells from BN-1L rats express an increased amount of IL-4 mRNA but produce less IL-10. Furthermore, the sera from BN-1L rats contain higher amounts of active TGF-beta1. Therefore, we have investigated the involvement of IL-4 and TGF-beta in the resistance of BN-1L rats to develop EAE using neutralizing mAb. Neutralization of TGF-beta, but not IL-4, renders BN-1L rats susceptible to clinical EAE without affecting the proliferation or the cytokine repertoire of immune lymph node cells. With respect to the origin of the endogenous TGF-beta production, we excluded the involvement of CD8 T cells and discuss a possible role of platelets and of CD4 T cells exhibiting the CD45RC(low) phenotype.

Multi-Modal Antigen Specific Therapy for Autoimmunity

Peripheral tolerance, represents an attractive strategy to down-regulate previously activated T cells and suppress an ongoing disease. Herein, immunoglobulins (Igs) were used to deliver self and altered self peptides for efficient peptide presentation without costimulation to test for modulation of experimental allergic encephalomyelitis (EAE). Accordingly, the encephalitogenic proteolipid protein (PLP) sequence 139–151 (referred to as PLP1) and an altered form of PLP1 known as PLP-LR were genetically expressed on Igs and the resulting Ig-PLPl and Ig-PLP-LR were tested for efficient presentation of the peptides and for amelioration of ongoing EAE. Evidence is presented indicating that Ig-PLPl as well as Ig-PLP-LR given in saline to mice with ongoing clinical EAE suppresses subsequent relapses. However, aggregation of both chimeras allows crosslinking of Fcγ receptors (FcγRs) and induction of IL-10 production by APCs but does not promote the up-regulation of costimulatory molecules. Consequently, IL-10 displays bystander suppression and synergizes with presentation without costimulation to drive effective modulation of EAE. As Ig-PLP1 is more potent than Ig-PLP-LR in the down-regulation of T cells, we conclude that peptide affinity plays a critical role in this multi-modal approach of T cell modulation.

Human nerve growth factor protects common marmosets against autoimmune encephalomyelitis by switching the balance of T helper cell type 1 and 2 cytokines within the central nervous system.

Multiple sclerosis is a demyelinating disorder of the central nervous system (CNS), in which an immune attack directed against myelin constituents causes myelin destruction and death of oligodendrocytes, the myelin-producing cells. Here, the efficacy of nerve growth factor (NGF), a growth factor for neurons and oligodendrocytes, in promoting myelin repair was evaluated using the demyelinating model of experimental allergic encephalomyelitis (EAE) in the common marmoset. Surprisingly, we found that NGF delayed the onset of clinical EAE and, pathologically, prevented the full development of EAE lesions. We demonstrate by immunocytochemistry that NGF exerts its antiinflammatory effect by downregulating the production of interferon gamma by T cells infiltrating the CNS, and upregulating the production of interleukin 10 by glial cells in both inflammatory lesions of EAE and normal-appearing CNS white matter. Thus, NGF, currently under investigation in human clinical trials as a neuronal trophic factor, may be an attractive candidate for therapy of autoimmune demyelinating disorders.

The complexicity of cytokine treatment in ongoing EAE induced with MBP peptide 68-86 in Lewis rats.

IL-10 and TGF-beta1 are important immunoregulatory cytokines associated with clinical remissions in multiple sclerosis and amelioration of experimental allergic encephalomyelitis (EAE). IL-10 and TGF-beta1 have previously been shown to prevent the development of EAE. Here, we study effects of IL-10 and TGF-beta1 in ongoing EAE. When IL-10 or TGF-beta1 was administered by the nasal route from day 0 to day 7 postimmunization (pi), both IL-10 and TGF-beta1 prevented the development of acute EAE in Lewis rats. When IL-10 or TGF-beta1 was administered by the nasal route from day 5 to day 12 pi, both IL-10 and TGF-beta1 failed to influence clinical EAE. The inhibition of clinical EAE severity in IL-10-prevented rats was associated with reduced proliferation, IFN-gamma mRNA expression, and IFN-gamma secretion, while proliferation as well as IFN-gamma mRNA expression and secretion were augmented in TGF-beta1-prevented rats. TGF-beta1-prevented rats exhibited high levels of NO production by DC, which may mediate apoptosis of CD4+ T cells and of the DC themselves. For prevention, both IL-10 and TGF-beta1 inhibited infiltration of CD4+ T cells within the CNS, but neither IL-10 nor TGF-beta1 induced immune deviation from Th1 to Th2. Expression of IL-4 mRNA was not altered in IL-10- and TGF-beta1-prevented rats. These results demonstrate that IL-10 and TGF-beta administration by the nasal route can prevent the development of acute EAE, but by different mechanisms. The findings in rats with ongoing EAE have implications for the clinical application of cytokine treatment in autoimmune diseases.

Mechanisms of Suppression of Experimental Autoimmune Encephalomyelitis by Intravenous Administration of Myelin Basic Protein: Role of Regulatory Spleen Cells

Experimental allergic encephalomyelitis (EAE) can be downregulated by intravenous (iv) administration of myelin basic protein (MBP). In this report we show that downregulation of EAE by two 500-μg doses of MBP administered iv before immunization was associated with reduced encephalitogenicity of both spleen and lymph node cells (day 12 postimmunization) in adoptive transfer studies. However, efficient downregulation of EAE by two 500-μg iv doses of MBP on days 10 and 11 after active immunization (at the time of disease onset) was associated with no significant change in the encephalitogenicity of lymph node cells, but a complete abrogation of the ability of spleen cells (both at day 12 postimmunization) to transfer EAE compared to controls. Furthermore, coculture of spleen cells from rats tolerized by iv MBP on days 10 and 11 after active immunization with MBP with MBP-reactive T cells resulted in a decreased ability of the spleen T cells to transfer EAE compared to effector cells in monoculture. In contrast, coculture of MBP-reactive T cells with spleen cells from rats tolerized by iv MBP on days 14 and 7 before active immunization resulted in increased disease in recipient rats. These results suggest that reversal of clinical EAE by iv injection of MBP at the time of disease onset is due at least in part to a T cell control mechanism located in the spleen and suggest the presence of splenocyte regulatory cells that can suppress the ability of encephalitogenic T cells to induce EAE.