Manifestations Of Experimental Allergic Encephalomyelitis Research Articles

Gene-Based Delivery of IFN-β Is Efficacious in a Murine Model of Experimental Allergic Encephalomyelitis

Experimental allergic encephalomyelitis (EAE) is a model of central nervous system (CNS) inflammation that follows immunization with certain CNS antigens. The course and clinical manifestations of EAE are similar to those of multiple sclerosis (MS) in humans; therefore, EAE has become an accepted animal model to study MS. The purpose of this study was to demonstrate that systemic expression of murine interferon-beta (IFN-beta) (MuIFN-beta), following intramuscular (i.m.) delivery of plasmid DNA encoding MuIFN-beta to the hind limb of mice, is effective in reducing the clinical manifestations of disease in a model of EAE. The results of the study demonstrate that gene-based delivery of MuIFN-beta caused significantly decreased clinical scores compared with delivery of the null vector. A single injection of the MuIFN-beta plasmid was as effective in reducing the severity of the disease as an every other day injection of MuIFN-beta protein.

960. Gene-Based Delivery of Interferon-beta Is Efficacious in a Murine Model of Acute Experimental Allergic Encephalomyelitis

Experimental Allergic Encephalomyelitis (EAE) is a model of central nervous system (CNS) inflammation that ensues following immunization with certain CNS antigens, for example brain derived proteolipid or myelin basic protein. The course and clinical manifestations of EAE are similar to multiple sclerosis (MS) in humans and it has become an accepted animal model to study MS. There have been several reports in which Interferon-beta (IFN-b) protein has been shown to be effective in murine and rat models of EAE. It has also been shown that local CNS delivery of a plasmid DNA encoding IFN-b decreased the severity of the disease. The purpose of this study was to demonstrate that systemic expression of murine IFN-b (mIFN-b) following gene-based delivery of plasmid DNA to hind limb skeletal muscle is effective in reducing the clinical manifestations of disease in a rodent EAE model.

Effect of nicotinamide on the development of allergic encephalomyelitis

Daily injections of nicotinamide to guinea pigs immunized with an encephalitogenic preparation from day 1 through 16 postimmunization suppress the development of clinical manifestations of experimental allergic encephalomyelitis and reduce mortality of experimental animals. In nicotinamide-treated animals, weakened delayed-type hypersensitivity skin reactions to myelin and adhesive activity of peripheral blood leukocytes as well as enhanced cytochrome P-450-dependent monooxygenase activity are noted.

Suppression of experimental allergic encephalomyelitis in the Lewis rat, by administration of an acylated synthetic peptide of myelin basic protein

A Myelin Basic Protein (MBP) epitope encephalitogenic for the Lewis rat (amino acid residues 68–86) was synthesized and acylated by the attachment of a palmitoyl residue. Lewis rats treated intravenously (i.v.) with the palmitoylated peptide alone were better protected against clinical manifestations of experimental allergic encephalomyelitis (EAE) than rats treated with the peptide inserted into liposomes or with the native peptide at similar doses. The administration of the acylated peptide (PAL68 86) conferred excellent protection against a challenge with the encephalitogenic peptide (p68–86) or with the intact MBP molecule, both before and after induction of active disease, and also when administered to recipients after the transfer of lymphocytes from MBP-challenged donors. Histological manifestations were also reduced to a statistically significant degree. Treatment with a palmitoylated peptide from a non-encephalitogenic region of the MBP molecule (PAL44–62) or with a palmitoylated unrelated peptide were ineffective. In vitro Ag-specific proliferative responses as well as the ability to transfer disease to syngeneic recipients, by lymph node lymphocytes from PAL68–86-treated donors, were considerably reduced. Addition of IL-2 to these cultures failed to restore either Ag-specific responsiveness or the ability of the cells to transfer disease. The results suggest that the administration of acylated peptides induces a profound state of unresponsiveness, and thus may provide an effective means for treating T cell-mediated autoimmune inflammatory disorders.

B7-mediated costimulation can either provoke or prevent clinical manifestations of experimental allergic encephalomyelitis.

T-cell activation requires signalling provided by ligation of the T-cell receptor for antigen (TCR) and a second antigen (Ag) nonspecific signal, known as costimulation. The B7 receptors, CD80 (B7-1) and CD86 (B7-2), on the Ag-presenting cell (APC), interact with T-cell CD28 or CTLA-4 to deliver a costimulatory signal, which is particularly important for Th1 activation. Experimental allergic encephalomyelitis (EAE) is an autoimmune disorder, induced by Th1 cells directed against myelin antigens that provides an in vivo model for studying the role of B7-mediated costimulation in the induction of a pathological immune response. Using a soluble fusion protein ligand for the B7 receptors, as well as specific monoclonal antibodies specific for either CD80 or CD86, it has been demonstrated that B7 costimulation plays a prominent role in determining clinical disease outcome in EAE. Here we review recent data indicating that a paradoxical exacerbation of disease as well as the expected amelioration of disease can occur with costimulatory receptor blockade.

Effects of staphylococcal enterotoxin B on T cell receptor Vβ utilization and clinical manifestations of experimental allergic encephalomyelitis

Staphylococcal enterotoxin B (SEB) is a superantigen (SA) that up-regulates and then subsequently down-regulates and deletes T cells expressing Vβ8 T cell receptor (TcR) chains (Marrack and Kappler, 1990; Johnson et al., 1991). We have investigated the effect of SEB on experimental allergic encephalomyelitis (EAE) in PL/J mice, where the predominant encephalitogenic T cells are Vβ8 + (Acha Orbea et al., 1988; Zamvil et al., 1988). SEB did not enhance induction of EAE when administered prior to or after immunization for EAE. PL/J mice pretreated with SEB developed anergy and deletion of Vβ8 bearing cells and concomitant reduction in the incidence of EAE. Following SEB pretreatment, a redistribution in the TcR utilization of MBP-specific lymphocytes occurred. As a result, there was a low frequency of Vβ8 and expansion of other, normally less frequent, myelin basic protein (MBP)-specific clones. These observations indicate that systemic exposure to superantigen can influence organ-specific autoimmune diseases. We observed Vβ-specific elimination, rather than activation, of autoimmune clones, a finding of potential therapeutic value. Modification of the TcR repertoire by systemic exposure to this SA indicates plasticity of immune reactivity and demonstrates a mechanism by which an environmental exposure (SEB) can influence a genetically determined, T cell mediated autoimmune disease.

Effect of HgCl2 on experimental allergic encephalomyelitis in Lewis rats. HgC12i-nduced down-modulation of the disease

HgCl2 induces autoimmunity in Brown-Norway rats and immunosuppression in Lewis rats. In the latter rats, HgCl2 triggers the proliferation of T suppressor/cytotoxic (OX8+) cells which actively suppress T cell functions. This led us to study the effect of HgCl2 on experimental allergic encephalomyelitis (EAE), a T cell-mediated autoimmune disease obtained following immunization with basic protein (BP). It will be shown that HgCl2 attenuates or even prevents clinical manifestations of EAE and inhibits both the proliferative response of T cells to BP and the anti-BP antibody response. This immunosuppression was not due to a defect at the T helper cell or antigen-processing cell level but to the emergence of T suppressor cells.

Suppression of clinical signs of cell-transferred experimental allergic encephalomyelitis and altered cerebrovascular permeability in Lewis rats treated with a plasminogen activator inhibitor

The purpose of this study was to determine whether fibrinolysis resulting from activation of the clotting cascade in juxtaposition to endothelial cells of the central nervous system (CNS) microvasculature is important for development of clinical signs of experimental allergic encephalomyelitis (EAE) in recipient Lewis rats. Rats were injected with previously primed syngeneic lymph node cells, activated in vitro with guinea pig myelin basic protein, and subsequently treated daily with trans-4-(aminomethyl)cyclohexanecarboxylic acid (AMCA), a synthetic inhibitor of plasminogen activator. Clinical signs of EAE were significantly suppressed in AMCA-treated rats compared to saline-treated control recipient animals. Furthermore, suppression of clinical signs in AMCA-treated rats was accompanied by a significant curtailment in EAE-associated increased permeability of the blood-brain barrier (BBB). These findings provide evidence that CNS-associated deposition of fibrin and ensuing fibrinolysis, together with increased permeability of the BBB, are related prerequisite events for expression of clinical manifestations of EAE.

Effect of treatment with copolymer 1 (Cop-1) on the in vivo and in vitro manifestations of experimental allergic encephalomyelitis (EAE)

Injections of Copolymer 1 (Cop-1), a synthetic cathodic polymer, have been reported to prevent and treat successfully acute and recurrent EAE and has been employed in patients with multiple sclerosis (MS). It has been suggested that the therapeutic effect is due to cell-mediated immune (CMI) cross-reactivity between Cop-1 and myelin basic protein (MBP), the antigen that induces EAE. We found that Cop-1 treatment of guinea pigs (GP) sensitized with MBP in adjuvant (20 μg-animal): (a) lowers the incidence of clinical disease ( 8 20 vs 14 15 ); (b) decreases severity of disease in affected GP; (c) has little effect on pathologic lesions (mean pathology index ± SEM: 1.2 ± 0.2 vs 1.6 ± 0.3; P > 0.1). Lymphocytes of MBP-sensitized GP treated with Cop-1 exhibited in vitro proliferative responses to MBP equivalent to lymphocytes of untreated EAE-GP (14,134 ± 6,532 vs 11,821 ± 3,874; mean cpm ± SEM). GP sensitized to MBP or Cop-1 (100 μg/animal) showed reactivity to the sensitizing antigen but little in vitro reactivity to the other antigen. There was no correlation between the in vitro lymphocytes response to MBP and Cop-1 in individual GP. Treatment of MBP sensitized GP with calf-thymus histone (CTH) also resulted in a lower incidence of clinical EAE with less severe disease in affected GP. There was little effect on the pathologic index and no evidence of either inhibition of MBP-induced lymphocyte proliferative responses or cross-reactivity between MBP and CTH. Thus, treatment with Cop-1 or CTH inhibits clinical manifestations of acute EAE without suppressing inflammatory cell infiltrates or sensitization to MBP.

Experimental allergic encephalomyelitis in Lewis rats: inhibition by bacterial lipopolysaccharides and acquired resistance to reinduction by challenge with myelin basic protein.

In 2-mo-old Lewis rats immunized with bacterial lipopolysaccharides (LPS) precomplexed to guinea pig myelin basic protein (BP), the clinical and histologic manifestations of experimental allergic encephalomyelitis (EAE) were diminished compared with BP-treated controls. Similarly, in animals immunized with BP and challenged with BP-LPS at the same time or as long as 5 days after, the immunization with BP also inhibited the disease. That this capacity to reduce the incidence of BP-induced EAE is a unique property of LPS was suggested by the fact that other negatively charged molecules, such as DNA, RNA, and dextran sulphate, were not effective in inhibiting the clinical signs of EAE. After recovery from EAE induced by BP, some animals develop a recurrence of the disease if challenged with BP at appropriate intervals. However, after recovery from mild EAE induced by BP-LPS and after challenges with EAE-initiating BP antigens, secondary EAE was inhibited significantly.

Acceleration of experimental allergic encephalomyelitis in hamsters with antecedent virus infection

As previously reported, random bred hamsters, sensitized with neuroantigen and immunologic adjuvants, seldom exhibit clinical or histopathologic manifestations of experimental allergic encephalomyelitis (EAE) before 40–250 days (mean 95 ± 6 days) postsensitization. When hamsters were infected intracerebrally with hamster brain subacute sclerosing panencephalitis virus (HBS) prior to sensitization, 34% of the animals developed EAE acutely. Extending these studies which focus on the role of persistent virus infection of the CNS in rendering hamsters more susceptible to EAE, it is now apparent as described here that a major effect of virus in the central nervous system is to significantly reduce the latent period between sensitization and onset of paralysis. Intraperitoneal infection with HBS virus, on the other hand, does not accelerate the onset of EAE suggesting that altered patterns of EAE in HBS-infected hamsters are due to virus-induced changes in the target tissue.

The presence of specific antigen-reactive cells during the induction, recovery, and resistance phases of experimental allergic encephalomyelitis

Experimental allergic encephalomyelitis (EAE) is an induced disorder in which an autoimmune response specific for myelin basic protein (BP) results in neural tissue destruction and acute paralysis. Lewis rats rapidly recover from induced paralysis and do not display any clinical manifestations of EAE following a second BP injection. The object of this study was to determine if immunologic recognition of encephalitogenic fragments of the BP molecule occurs during the induction, recovery, and resistance phases of EAE. Paralysis was induced in Lewis rats by a single injection of BP in complete Freund's adjuvant (CFA). The results indicate that macrophage migration inhibition in the presence of encephalitogenic BP fragments containing amino acid residues 43–88 and 68–88 is detectable during the paralytic stage of EAE, and also following recovery from clinical neurologic impairment. Although rats which had recovered were resistant to secondary BP-induced paralysis, macrophage migration inhibition in the presence of BP, or its encephalitogenic fragments, was detected after the second BP-CFA challenge. In order to assess humoral immunologic recognition, levels of serum antibody specific for the 43–88 BP fragment were determined. Specific antibody was not detected during the paralytic episode, but appeared upon recovery. Specific antibody was also detected following the secondary BP-CFA challenge. These data indicate that antigen-sensitive cells are present during the induction, recovery, and resistance phases of EAE in the Lewis rat. The mechanism which controls the activity of these cells in vivo has not been established.

Experimental allergic encephalomyelitis in cobra venom factor-treated and C4-deficient guinea pigs.

Experimental allergic encephalomyelitis (EAE) was studied in guinea pigs with an inherited deficiency of the fourth component of complement (C4) and in guinea pigs injected with cobra venom factor to deplete the third component and late-acting components of complement. EAE was elicited by immunization with homologous spinal cord or purified basic protein. Administration of cobra factor after the injection of encephalitogenic emulsion delayed the onset and reduced the intensity of the clinical manifestations of EAE. In addition, cobra factor markedly reduced mortality during the sixty days of observation. However, pathological changes of perivascular infiltration and demyelination were similar in cobra factor-treated and untreated animals. Clinical signs of EAE an mortality in C4-deficient guinea pigs were no different from those in normocomplementemic controls. Thus, although activation of the classic complement pathway does not appear to be involved in the production of EAE in guinea pigs, our results suggest a possible role of the alternative complement pathway in the pathogenesis of EAE.

Immune responses to myelin basic protein in mycobacterial-induced suppression of experimental allergic encephalomyelitis

Pretreatment of guinea pigs with complete Freund's adjuvant (CFA) 21 days prior to injection with myelin basic protein (BP) in CFA resulted in marked attenuation of clinical and pathologic manifestations of experimental allergic encephalomyelitis (EAE). Delayed hypersensitivity skin tests to homologous BP were likewise depressed in protected animals. The protected guinea pigs also demonstrated diminished in vitro reactivity to BP as assessed by BP-induced proliferative response of peritoneal exudate cells (PEC) and BP-induced inhibition of macrophage migration. Broad-based suppression of immunologic reactivity did not occur in these animals, as manifested by larger skin tests to PPD, a greater proliferative response to old tuberculin (OT), by PEC and peripheral blood lymphocytes (PBL), as well as marked PPD-induced inhibition of macrophage migration. Diminution of the degree of cell-mediated reactivity to BP may be one of the mechanisms by which prior treatment with CFA suppresses subsequent development of EAE.