IL-4, IL-10, IL-13, and TGF-beta from an altered peptide ligand-specific Th2 cell clone down-regulate adoptive transfer of experimental autoimmune encephalomyelitis.
(65/2313)
Experimental autoimmune encephalomyelitis (EAE) is induced in the SJL/J mouse by adoptive transfer of activated proteolipid protein peptide (PLP) 139-151-specific Th1 cells. T cells responding to altered peptide ligands (APL) of PLP, previously shown to induce Th2 differentiation and regulate disease in PLP-immunized mice, do not transfer EAE. However, the exact mechanism of disease regulation by APL-specific T cells has not been elucidated. In this report, we show that 1F1, a Th2 clone specific for an APL of PLP139-151 can prevent adoptive transfer of EAE when cocultured with PLP-encephalitogenic spleen cells (PLP-spleen). Cytokines from activated 1F1 cells were detected by hybridization of mRNA to oligonucleotide arrays (DNA chip) and by ELISA. The Th2 cytokines found to be present at the highest protein and mRNA levels were evaluated for their role in suppression of adoptive transfer of EAE from PLP-activated spleen cell cultures. Abs to individual cytokines in 1F1 PLP-spleen cocultures suggested that IL-4, IL-13, and TGF-beta played a significant role in suppressing EAE. Abs to the combination of IL-4, IL-10, IL-13, and TGF-beta completely neutralized the protective effect of 1F1. Addition of Th2 cytokines to PLP-spleen cultures showed that IL-13 and TGF-beta were each individually effective and low levels of IL-4 synergized with IL-13 to inhibit disease transfer. IL-5, IL-9, and IL-10 had little or no effect whereas GM-CSF slightly enhanced EAE. Our results demonstrate that Th2 cytokines derived from APL-specific Th2 cells can effectively down-regulate the encephalitogenic potential of PLP-spleen cells if present during their reactivation in culture. (+info)
Fulminant spontaneous autoimmunity of the central nervous system in mice transgenic for the myelin proteolipid protein-specific T cell receptor.
(66/2313)
Proteolipid protein (PLP)-139-151 is the dominant encephalitogenic peptide that induces experimental autoimmune encephalomyelitis (EAE) in SJL (H-2(s)) mice. To examine the contribution of T cell receptor (TCR) specificity in the induction of EAE, we generated transgenic mice expressing the rearranged TCR genes from an encephalitogenic or a nonencephalitogenic PLP-139-151/I-A(s)-specific T cell clone. Both types of transgenic lines developed spontaneous EAE, but, remarkably, the lines expressing the TCR from the nonencephalitogenic clone showed increasingly higher frequencies of disease (60-83%) in progressive SJL backcrosses and could not be propagated on the susceptible background. The T cells from the transgenic mice were not tolerized, because they responded vigorously to the antigen in vitro and mediated EAE when the mice were immunized with antigen. Besides being the only description of a TCR transgenic mice for the PLP-139-151/I-A(s) epitope, the results demonstrate that the TCR from a nonencephalitogenic PLP-specific T cell clone can induce autoimmune disease when expressed appropriately in vivo. (+info)
Uric acid, a peroxynitrite scavenger, inhibits CNS inflammation, blood-CNS barrier permeability changes, and tissue damage in a mouse model of multiple sclerosis.
(67/2313)
Peroxynitrite (ONOO(-)), a toxic product of the free radicals nitric oxide and superoxide, has been implicated in the pathogenesis of CNS inflammatory diseases, including multiple sclerosis and its animal correlate experimental autoimmune encephalomyelitis (EAE). In this study we have assessed the mode of action of uric acid (UA), a purine metabolite and ONOO(-) scavenger, in the treatment of EAE. We show that if administered to mice before the onset of clinical EAE, UA interferes with the invasion of inflammatory cells into the CNS and prevents development of the disease. In mice with active EAE, exogenously administered UA penetrates the already compromised blood-CNS barrier, blocks ONOO(-)-mediated tyrosine nitration and apoptotic cell death in areas of inflammation in spinal cord tissues and promotes recovery of the animals. Moreover, UA treatment suppresses the enhanced blood-CNS barrier permeability characteristic of EAE. We postulate that UA acts at two levels in EAE: 1) by protecting the integrity of the blood-CNS barrier from ONOO(-)-induced permeability changes such that cell invasion and the resulting pathology is minimized; and 2) through a compromised blood-CNS barrier, by scavenging the ONOO(-) directly responsible for CNS tissue damage and death. (+info)
Role of passive T-cell death in chronic experimental autoimmune encephalomyelitis.
(68/2313)
The mechanisms of chronic disease and recovery from relapses in experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis, are unknown. Deletion of myelin-specific lymphocytes by apoptosis may play a role in termination of the inflammatory response. One pathway of apoptosis is the passive cell death or "cell death by neglect" pathway, which is under the control of the Bcl family of genes. To investigate the role of passive cell death pathway in EAE, we used mice with transgenic expression of the long form of the bcl-x gene (Bcl-x(L)) targeted to the T-cell lineage. We found that mice transgenic for Bcl-x(L) have an earlier onset and a more chronic form of EAE induced by myelin oligodendrocyte glycoprotein (MOG) peptide 35-55 compared with wild-type littermate mice. This was not due to an expanded autoreactive cell repertoire. Primed peripheral lymphocytes from Bcl-x(L) transgenic mice showed increased proliferation and cytokine production to MOG peptide in vitro compared with lymphocytes from wild-type animals. Immunohistologic studies demonstrated increased cellular infiltrates, immunoglobulin precipitation, and demyelination in the Bcl-x(L) transgenic central nervous system (CNS) compared with controls. There was also a decreased number of apoptotic cells in the CNS of Bcl-x(L) transgenic mice when compared with littermates at all time points tested. This is the first report of an autoimmune disease model in Bcl-x(L) transgenic mice. Our data indicate that the passive cell death pathway is important in the pathogenesis of chronic EAE. These findings have implications for understanding the pathogenesis of multiple sclerosis and other autoimmune diseases. (+info)
Short-lived immunization site inflammation in self-limited active experimental allergic encephalomyelitis.
(69/2313)
To understand the mechanisms underlying spontaneous remission of proteolipid protein (PLP) 139-151 peptide-induced experimental allergic encephalomyelitis (EAE), an acute autoimmune disease of SJL mice resembling human multiple sclerosis, we examined both the effector response site in the central nervous system (CNS) and the immunization site at different phases of the disease. In the CNS, the frequency of PLP 139-151 peptide-specific IFN-gamma-producing T cells as well as the amount of infiltrating CD4(+) and CD11b(+) cells decreased with recovery. However, IL-4-producing cells were always rare and cyclooxygenase-2(+) cells were numerous only at disease peak in the CNS, suggesting that T(h)2 cytokines and prostaglandins did not determine remission of EAE. By looking at the s.c. site of PLP 139-151 peptide plus adjuvant injection, we found that, although the inflammatory infiltrate was abundant, CD11b(+) cells started to decrease already during disease acute phase and DEC-205(+) cells were numerous only at early time points. We propose that immunization site inflammation is short-lived in PLP 139-151 peptide-induced EAE, and this leads to a temporary autoreactive T cell stimulation and to a self-limited disease. (+info)
The heat-stable antigen determines pathogenicity of self-reactive T cells in experimental autoimmune encephalomyelitis.
(70/2313)
Induction of myelin-specific CD4 T cells is a pivotal event in the development of experimental autoimmune encephalomyelitis (EAE). Other checkpoints in EAE pathogenesis have not been clearly defined, although multiple genetic loci are known to influence EAE development. We report here that targeted mutation of the heat-stable antigen (HSA) abrogates development of EAE despite a complete lack of effect on induction of autoimmune T cells. To test whether T-cell expression of HSA is sufficient, we created transgenic mice in which HSA is expressed exclusively in the T-cell lineage. We found that these mice remain resistant to EAE induction. Adoptive transfer studies demonstrate that both T cells and non-T cells must express HSA in order for the pathogenic T cells to execute their effector function. Moreover, HSAIg, a fusion protein consisting of the extracellular domain of the HSA and the Fc portion of immunoglobulin, drastically ameliorates the clinical sign of EAE even when administrated after self-reactive T cells had been expanded. Thus, identification of HSA as a novel checkpoint, even after activation and expansion of self-reactive T cells, provides a novel approach for immunotherapy of autoimmune neurologic diseases, such as multiple sclerosis. (+info)
Repertoire requirements of CD4+ T cells that prevent spontaneous autoimmune encephalomyelitis.
(71/2313)
Spontaneous experimental autoimmune encephalomyelitis arises in 100% of mice exclusively harboring myelin basic protein-specific T cells, and can be prevented by a single injection of CD4+ T cells obtained from normal donors. Given the powerful regulatory effect of the transferred T cells, we further investigated their properties, and, in particular, their repertoire requirements. Transfer of monoclonal OVA-specific CD4+ T cells did not confer protection from disease even when present at very high proportions (about 80% of total lymphocytes). Lack of protection was also evident after immunization of these animals with OVA, indicating that not just any postthymic CD4+ T cells has the potential to become regulatory. However, protection was conferred by cells bearing limited TCR diversity, including cells expressing a single Valpha4 TCR chain or cells lacking N nucleotides. We also investigated whether coexpression of the myelin basic protein-specific TCR with another TCR in a single cell would alter either pathogenesis or regulation. This was not the case, as myelin basic protein-specific/OVA-specific recombinase activating gene-1-/- double TCR transgenic mice still developed experimental autoimmune encephalomyelitis spontaneously even after immunization with OVA. Based on this evidence, we conclude that CD4+ T regulatory cells do not express canonical TCRs and that the altered signaling properties brought about by coexpression of two TCRs are not sufficient for the generation of regulatory T cells. Instead, our results indicate that regulatory T cells belong to a population displaying wide TCR diversity, but in which TCR specificity is central to their protective function. (+info)
Estrogen potentiates treatment with T-cell receptor protein of female mice with experimental encephalomyelitis.
(72/2313)
Transgenic mice expressing the BV8S2 chain, which is specific for the myelin basic protein determinant Ac1-11, possess a naturally induced set of regulatory T cells directed against BV8S2. Further activation of anti-BV8S2 T cells in male mice with recombinant BV8S2 protein can inhibit IFN-gamma release by Ac1-11-specific T cells through a cytokine-driven mechanism and prevent induction of experimental autoimmune encephalomyelitis (EAE). In contrast, naive female mice possess fewer anti-BV8S2-reactive T cells, and treatment with BV8S2 delayed but did not prevent EAE. We here demonstrate that combining T-cell receptor (TCR) vaccination with supplemental estrus doses of estrogen potentiated IL-10 production by anti-BV8S2-reactive T cells and induced Ac1-11-specific T cells to produce IL-10 and TGF-beta. This combined treatment resulted in full protection against EAE, which was not observed with either therapy alone. These findings imply that supplemental estrogen can enhance the efficacy of TCR-based immunotherapy for autoimmune diseases that predominate in females. (+info)