Myelin Basic Protein Ac1-11 Research Articles

Bone marrow transplantation combined with gene therapy to induce antigen-specific tolerance and ameliorate EAE

Hematopoietic stem cell (HSC) transplantation is a potential therapy that can offer multiple sclerosis patients a radical, potentially curative treatment. Using experimental autoimmune encephalomyelitis (EAE) as a model, we previously reported that retrovirally transduced B cells expressing myelin basic protein (MBP), MBP Ac1-11, or myelin oligodendrocyte glycoprotein p35–55 induced tolerance and reduced symptoms. Here, we extend our tolerance approach using bone marrow (BM) cells expressing full-length phospholipid protein (PLP) in a model for relapsing, remitting EAE. Using GFP expression as a marker, we found that up to 50% of cells were positive for transgene expression in peripheral blood after 900 rad irradiation and transduced BM transplantation, and expression was stable in hematopoietic lineages for over 10 weeks. Upon challenge, T cell proliferation in response to PLP p139–151 was reduced and EAE was completely abolished in a pretreatment protocol. In addition, protection from EAE could be achieved with PLP-transduced BM cells given on day 12 after immunization, a potential therapeutic protocol. Finally, the protective effect of PLP-expressing BM could also be observed using a nonmyeloablative protocol, albeit with lower efficacy. Our results suggest that HSC may be useful to achieve long-lasting tolerance to protect mice from EAE and possibly to promote CNS repair in ongoing EAE.

Immune Regulatory Mechanisms Influence Early Pathology in Spinal Cord Injury and in Spontaneous Autoimmune Encephalomyelitis

Injuries to the central nervous system (CNS) trigger an inflammatory reaction with potentially devastating consequences. In this report we compared the characteristics of the inflammatory response on spinal cord injury (SCI) caused by a stab wound between the T7 and T9 vertebrae and spontaneous experimental autoimmune encephalomyelitis (EAE). SCI and EAE were compared in two types of myelin basic protein Ac1-11-specific T-cell receptor transgenic mice: T/R+ mice harbor regulatory T cells, and T/R- mice lack regulatory T cells. Our results show that 8 days after SCI, T/R- mice developed a strong T-cell infiltrate in the spinal cord, with remarkable down-modulation of CD4 expression that was accompanied by a local increase in Mac-3+ and F4/80+ reactivity and diffuse local and distal astrogliosis. In contrast, T/R+ mice exhibited a modest increase in CD4+ cells localized to the site of injury, without CD4 down-modulation; focal astrogliosis was restricted to the site of the lesion, although Mac-3+ and F4/80+ cells were also present. Similarly to T/R- mice that underwent SCI, T cells displaying down-modulated CD4 expression were found in the CNS of older T/R- mice afflicted by spontaneous EAE. Overall, our results suggest that common mechanisms regulate T-cell accumulation in CNS lesions of different causes, such as mechanic lesion or autoimmune-mediated damage.

Oral tolerance to copolymer 1 in myelin basic protein (MBP) TCR transgenic mice: cross-reactivity with MBP-specific TCR and differential induction of anti-inflammatory cytokines.

Oral tolerance to myelin basic protein (MBP) is an effective antigen-specific method to suppress experimental allergic encephalomyelitis (EAE). Glatiramer acetate [copolymer 1 (Cop1)] is a synthetic copolymer designed to mimic MBP which suppresses EAE, is used parenterally to treat multiple sclerosis (MS) and is being tested orally for efficacy in MS. We investigated the immunologic properties of Cop1 to determine the degree to which its effects were antigen specific using MBP TCR transgenic mice. Immunization of MBP TCR transgenic mice fed Cop1, MBP or MBP Ac1-11 resulted in decreased proliferation, and IL-2, IL-6 and IFN-gamma production, and increased secretion of IL-10 and transforming growth factor (TGF)-beta in Cop1-fed animals. IFN-gamma was decreased, and IL-10 and TGF-beta were increased in non-immunized mice fed Cop1 and stimulated in vitro with MBP. No such effects were observed in ovalbumin TCR transgenic mice. To determine if the effects of Cop1 were specific to MBP TCR-bearing cells, MBP TCR transgenic Rag2(-/-) mice were immunized and re-stimulated in vitro with Cop1. We found a marked increase in IL-4 and similar increases in IL-4 after feeding Cop1. In disease models, feeding Cop1 suppressed EAE in MBP TCR transgenic mice, (PL/J x SJL)F(1) mice, and in myelin oligodendrocyte glycoprotein-induced EAE in NOD mice. Oral Cop1 had no effect on collagen-induced arthritis. These results demonstrate that Cop1 is active orally in an antigen-specific fashion, and may function as an altered peptide ligand for MBP-specific TCR-bearing cells by decreasing pro-inflammatory cytokines (IFN-gamma) and increasing anti-inflammatory cytokines (IL-4, IL-10 and TGF-beta).

The role of CTLA-4 in tolerance induction and ttigen administration cell differentiation in experimental autoimmune encephalomyelitis: i. v. antigen administration.

Interactions between B7 molecules on antigen-presenting cells and CTLA-4 on T cells have been shown to be important in establishing tolerance. In the present study, we examined the kinetics of tolerance induction following i.v. administration of myelin basic protein (MBP) Ac1-11 in mice transgenic for a TCR V(beta)8.2 gene derived from an encephalitogenic T cell clone specific for MBP Ac1-11. Examination of the lymph node cell (LNC) response 10 days after antigen administration demonstrated an accentuation of i.v. tolerance induction with anti-CTLA-4 blockade. Anergy was induced in splenocytes by i.v. antigen administration as shown by a decrease in MBP-specific proliferation and IL-2 production, and anti-CTLA-4 potentiated this effect. In addition, i.v. antigen plus anti-CTLA-4 and complete Freund's adjuvant was not encephalitogenic. Interestingly, i.v. tolerance (a single injection) did not inhibit experimental autoimmune encephalomyelitis (EAE) and anti-CTLA-4 administration did not alter this phenotype. These results suggest that while the majority of MBP-specific T cells are tolerized by i.v. antigen and that this process is potentiated by anti-CTLA-4 administration, a population of T cells remains that is quite efficient in mediating EAE.

The role of CTLA-4 in tolerance induction and T cell differentiation in experimental autoimmune encephalomyelitis: i.p. antigen administration

Recent evidence suggests that co-stimulation provided by B7 molecules through CTLA-4 is important in establishing peripheral tolerance. In the present study, we examined the kinetics of tolerance induction and T cell differentiation following i.p. administration of myelin basic protein (MBP) Ac1-11 in mice transgenic for a TCR V(beta)8.2 gene derived from an encephalitogenic T cell clone specific for MBP Ac1-11. Examination of the lymph node cell response after antigen administration demonstrated a dependence on CTLA-4 for i.p. tolerance induction. Examination of splenocyte responses suggested that i.p. antigen administration induced a T(h)2 response, which was potentiated by anti-CTLA-4 administration. Interestingly, i.p. tolerance was able to inhibit the induction of experimental autoimmune encephalomyelitis and anti-CTLA-4 administration did not alter this phenotype, suggesting that CTLA-4 blockade did not block tolerance induction. Thus, T cell differentiation and the dependence on CTLA-4 for tolerance induction following i.p. antigen administration differs between lymph node and spleen in a model of organ-specific autoimmunity.

Microglia induce myelin basic protein-specific T cell anergy or T cell activation, according to their state of activation.

Microglial cells are non-professional antigen-presenting cells (APC) the function of which is still controversial. Here, we studied the function of microglia derived from H-2(u) mice. We show that these microglia express a low level of B7.2 and CD40 and, interestingly, lack surface expression of B7.1. Resting and IFN-gamma-activated microglia were unable to activate naive and primed myelin basic protein (MBP)-specific CD4(+) T cells in the presence of MBP and encephalomyelitic MBP Ac1-11 peptide. Furthermore, in the presence of Ac1-11 peptide, CD4(+) TCR-transgenic T cells became anergized. Microglia became professional APC only after a multistep activation process involving both stimulation through cytokines [granulocyte-macrophage colony-stimulating factor (GM-CSF) and IFN-gamma] and cognate signaling (B7-CD28 and CD40-CD40 ligand interactions). As such they were able to present MBP to both unprimed and primed T cells. Co-culture of microglia with GM-CSF up-regulated co-stimulatory molecules, in particular B7.1. Additional activation with IFN-gamma induced MHC class II and CD40 up-regulation. CD40-CD40 ligand interaction significantly enhanced microglial ability to prime TCR-transgenic T cells and was essential for presentation of MBP to in vivo primed non-transgenic T cells. We propose that microglia may serve different functions under different inflammatory conditions, depending on the cytokine milieu and the type of cognate interaction they are involved in.

IL-4 is a differentiation factor for transforming growth factor-beta secreting Th3 cells and oral administration of IL-4 enhances oral tolerance in experimental allergic encephalomyelitis.

We have previously shown that following oral administration of myelin basic protein (MBP), regulatory T cells are generated from gut-associated lymphoid tissue and that these cells suppress experimental allergic encephalomyelitis (EAE). These regulatory T cells produce transforming growth factor-beta (TGF-beta) with various amounts of IL-4 and IL-10 and these TGF-beta-secreting T cells have been termed Th3 cells. T cells in lymphoid organs drained by mucosal sites secrete IL-4 as a primary T cell growth factor. In the present study, we examined the role of IL-4 on oral tolerance and in the generation of TGF-beta secreting cells. Treatment of (PLJ x SJL)F1 mice with intraperitoneal (i. p.) IL-4 and low-dose oral MBP (0.5 mg) given three times reduced the severity of EAE, whereas i.p. injection of IL-4 alone or oral MBP alone given in these suboptimal doses, showed no protection. Spleen cells from protected mice produced increased amounts of TGF-beta and reduced IFN-gamma upon stimulation with MBP in vitro. Mucosal MBP-specific IgA production was significantly increased in IL-4 plus MBP fed animals. Moreover, oral administration of IL-4 (1 microg per feeding) also enhanced the suppression of EAE by oral MBP and this protective effect was reversed by administration of anti-TGF-beta antibody in vivo. Reverse transcription-PCR showed enhanced suppression of IFN-gamma in Peyer's patch in animals fed MBP and IL-4 versus those fed MBP alone. We then investigated the role of IL-4 in the generation of TGF-beta-secreting cells using MBP Ac1-11 TCR transgenic animals. Cells were cultured with IL-2, IL-4, or IFN-gamma in the presence of MBP and limiting dilution analysis for cytokine-secreting cells performed. We found that IL-4, but not IL-2 or IFN-gamma, generated TGF-beta-secreting T cells from naive splenic T cells and that these cells provided help for IgA production. These findings demonstrate that IL-4 is a differentiation factor for TGF-beta-secreting Th3 cells and oral IL-4 has a synergistic effect on low-dose oral tolerance that is associated with increased TGF-beta secretion.

Reversal of acute experimental autoimmune encephalomyelitis and prevention of relapses by treatment with a myelin basic protein peptide analogue modified to form long-lived peptide-MHC complexes.

Experimental autoimmune encephalomyelitis (EAE) is an autoimmune disease induced by immunization with myelin basic protein (MBP), proteolipid protein, or encephalitogenic peptides from these myelin components. EAE resembles basic protein multiple sclerosis in some of its clinical and histologic features, and serves as an experimental model for this and other autoimmune diseases. In this study, we examine i.v. peptide therapy of EAE in detail, and show that repeated i.v. injections of MBP peptides effectively treat EAE in (PLJxSJL)F1 mice. In this study, administration of the immunodominant epitope (MBP Ac1-11) prevents MBP-induced disease, whereas the subdominant epitope MBP 31-47 is neither required nor sufficient. Intravenous administration of substituted MBP peptide analogues is also effective in treating EAE, provided the peptide side chains presumed to be involved in TCR contact and MHC binding are preserved. A substituted MBP peptide analogue that forms long-lived peptide-MHC complexes in vivo is more effective than the unmodified MBP peptide. Lower doses of the substituted peptide analogue are effective, and the effect is longer lasting than treatment with the unmodified peptide. Clinical signs of EAE are reversed by injection of the substituted peptide during the acute phase of disease. Moreover, treatment of mice in the remission phase of EAE results in a dramatically reduced incidence of relapse. In summary, we have shown that EAE can be reversed after onset and treated during remission with an MBP peptide analogue that has been modified for improved therapeutic potency.

A polyalanine peptide with only five native myelin basic protein residues induces autoimmune encephalomyelitis.

The minimum structural requirements for peptide interactions with major histocompatibility complex (MHC) class II molecules and with T cell receptors (TCRs) were examined. In this report we show that substituting alanines at all but five amino acids in the myelin basic protein (MBP) peptide Ac1-11 does not alter its ability to bind A alpha uA beta u (MHC class II molecules), to stimulate specific T cells and, surprisingly, to induce experimental autoimmune encephalomyelitis (EAE) in (PL/J x SJL/J)F1 mice. Most other amino acid side chains in the Ac1-11 peptide are essentially irrelevant for T cell stimulation and for disease induction. Further analysis revealed that binding to A alpha uA beta u occurred with a peptide that consists mainly of alanines and only three of the original residues of Ac1-11. Moreover, when used as a coimmunogen with MBP Ac1-11, this peptide inhibited EAE. The finding that a specific in vivo response can be generated by a peptide containing only five native residues provides evidence that disease-inducing TCRs recognize only a very short sequence of the MHC-bound peptide.