Identification of new serum autoantibodies in neuromyelitis optica using protein microarrays.
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Adult↗
Biomedical subjects
C P Genain
Publications and source records attributed to C P Genain.
Activity of a newly identified serine protease in CNS demyelination.
We have identified a novel serine protease, myelencephalon-specific protease (MSP), which is preferentially expressed in the adult CNS, and therein, is abundant in both neurones and oligodendroglia. To determine the potential activity of MSP in CNS demyelination, we examined its expression in multiple sclerosis lesions and in two animal models of multiple sclerosis: Theiler's murine encephalomyelitis virus (TMEV) and myelin oligodendrocyte glycoprotein (MOG)-induced experimental allergic encephalomyelitis (EAE) in marmosets. High levels of MSP were present within infiltrating mononuclear cells, including macrophages and T cells, which characteristically fill sites of demyelination, both in multiple sclerosis lesions and in animal models of this disease. The functional consequence of excess MSP on oligodendroglia was determined in vitro by evaluating the effects of recombinant MSP (r-MSP) on oligodendrocyte survival and process number. Application of excess r-MSP resulted in a dramatic loss of processes from differentiated oligodendrocytes, and a parallel decrease in process outgrowth from immature cells. Transfection of oligodendrocyte progenitors with an MSP-green fluorescent protein construct produced similar changes in oligodendrocyte process number. Importantly, r-MSP did not affect oligodendrocyte survival or differentiation towards the sulphatide-positive lineage. We further demonstrate that myelin basic protein, and to a lesser extent myelin oligodendrocyte glycoprotein, can serve as MSP substrates. These studies support the hypothesis that excess MSP, as is present in inflammatory CNS lesions, promotes demyelination.
Animals↗
Effective antigen-specific immunotherapy in the marmoset model of multiple sclerosis.
Mature T cells initially respond to Ag by activation and expansion, but high and repeated doses of Ag cause programmed cell death and can suppress T cell-mediated diseases in rodents. We evaluated repeated systemic Ag administration in a marmoset model of experimental allergic encephalomyelitis that closely resembles the human disease multiple sclerosis. We found that treatment with MP4, a chimeric, recombinant polypeptide containing human myelin basic protein and human proteolipid protein epitopes, prevented clinical symptoms and did not exacerbate disease. CNS lesions were also reduced as assessed in vivo by magnetic resonance imaging. Thus, specific Ag-directed therapy can be effective and nontoxic in primates.
Animals↗
Treatment of depression is associated with suppression of nonspecific and antigen-specific T(H)1 responses in multiple sclerosis.
OBJECTIVE: To examine the relationship between depression, treatment of depression, and interferon gamma (IFN-gamma) production by peripheral blood mononuclear cells in patients with comorbid diagnoses of relapsing-remitting multiple sclerosis (MS) and major depressive disorder. DESIGN: A randomized comparative outcome trial of three 16-week treatments for depression. Assessments were conducted at baseline, week 8, and treatment cessation. SETTING: An academic outpatient treatment and clinical research center. PATIENTS: Fourteen patients who met the criteria for relapsing-remitting MS and major depressive disorder. INTERVENTIONS: Individual cognitive behavioral therapy, group psychotherapy, or sertraline therapy. MAIN OUTCOME MEASURES: Depression was assessed using the Beck Depression Inventory. Interferon gamma production by peripheral blood mononuclear cells was measured following stimulation with OKT3 or recombinant human myelin oligodendrocyte glycoprotein (MOG). Variability in immune assays was controlled using 8 nondepressed healthy subjects who were enrolled at times corresponding with the enrollment of MS patients. RESULTS: Results of the Beck Depression Inventory were significantly related to IFN-gamma production stimulated with OKT3 or MOG at baseline (P< or = .03 for all). Level of depression, OKT3-stimulated IFN-gamma production, and MOG-stimulated IFN-gamma production all declined significantly over the 16-week treatment period (P< or = .03 for all). Among controls, there were no significant changes over time in OKT3- or MOG-stimulated IFN-gamma, or in depression (P> or = .25 for all). CONCLUSIONS: These findings suggest that the production of the proinflammatory cytokine IFN-gamma by autoaggressive T cells in relapsing-remitting MS is related to depression and that treatment of depression may decrease IFN-gamma production. Thus, treatment of depression may provide a novel disease-modifying therapeutic strategy as well as a symptomatic treatment for patients with MS.
Adult↗
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.
Animals↗
Characterization of the response to myelin basic protein in a non human primate model for multiple sclerosis.
The common marmoset Callithrix jacchus (C. jacchus) is an outbred species characterized by a naturally occurring bone marrow chimerism and susceptibility to a form of experimental autoimmune encephalomyelitis (EAE) resembling multiple sclerosis (MS). T cell clones specific for the myelin antigen, myelin basic protein (MBP), can be derived from both naive and immunized marmosets and can adoptively transfer EAE to compatible chimeric siblings. Here, we demonstrate that several different antigenic determinants of MBP are recognized by these encephalitogenic T cell clones. Furthermore, PCR-based analysis of TCR Vbeta families does not show the preferential usage of any gene segment. Characterization of third complementarity determining regions (CDR3) fails to demonstrate a recurring motif characteristic of the T cell immune response to MBP in this species. Nevertheless, brief amino acid motifs are shared among marmoset clones and CDR3 sequences from MS samples. These data suggest that, due to its outbred condition, the C. jacchus marmoset mounts a diverse pathogenic response to MBP. However, the findings that certain CDR3 sequences are identically expressed in different animals, or by different T cell clones, suggest that MBP-specific T cell populations may be clonally expanded following chronic antigenic stimulation in vivo.
Amino Acid Motifs↗
Characterization of the expressed immunoglobulin IGHV repertoire in the New World marmoset Callithrix jacchus.
The common marmoset (Callithrix jacchus jacchus) is a member of the Callithrichinae, a family of outbred New World primates with limited MHC polymorphisms and a propensity to develop spontaneous or experimentally induced autoimmunity. C. jacchus marmosets are susceptible to experimental allergic encephalomyelitis (EAE), and spontaneously develop autoimmune colitis and thyroiditis. Such disease models approximate the complexity of human autoimmune disorders, and allow an investigation of the respective roles of T-cell and antibody responses to self-antigens in outbred species. A key issue for further definition of the pathogenic antibody responses in human autoimmunity is to understand the diversity of the immunoglobulin repertoire in primate models. Here, we characterized the expressed immunoglobulin IGHV repertoire of the C. jacchus marmoset. Six IGHV subgroups were identified which show a high degree of sequence similarity to their human IGHV counterparts (IGHV1, IGHV3, IGHV4, IGHV5, IGHV6, and IGHV7). As in the expressed human IGHV repertoire, the framework regions are more conserved when compared to the complementarity-determining regions (CDRs), with the greatest degree of variability located in CDR3. Predicted structural features are highly conserved between C. jacchus and human IGHV. This information now provides a framework for studies of the antigen-specific repertoire of pathogenic antibodies in EAE and other immune-mediated diseases.
Amino Acid Sequence↗
Immune responses against the myelin/oligodendrocyte glycoprotein in experimental autoimmune demyelination.
Myelin/oligodendrocyte glycoprotein (MOG) is a surface-exposed antigen of myelin and an important target for autoimmune responses which mediate inflammatory demyelination in the central nervous system. Experimentally, MOG induces strong pathogenic T cell responses in many strains of laboratory animals. Immunological studies in humans also identify MOG as a surprisingly prevalent antigenic molecule among the myelin proteins. In addition, the encephalitogenic properties of MOG are linked to the induction of antibody responses which have been demonstrated to directly promote central nervous system demyelination, a hallmark neuropathological feature in disorders such as human multiple sclerosis. Factors responsible for autoimmunity to MOG likely include genetic influences as well as other mechanisms, which are the subject of intense investigation. This article reviews experimental data currently available on specificity and pathogenic roles of T cell and antibody responses against MOG, which have implications relevant to multiple sclerosis and related disorders.
Amino Acid Sequence↗
Experimental allergic encephalomyelitis in the New World monkey Callithrix jacchus.
Models that adequately reflect the complexity of human multiple sclerosis (MS) are needed, especially for preclinical testing of immunomodulatory drugs. Our group has created a unique experimental system in a New World outbred primate, the common marmoset Callithrix jacchus (C. jacchus). Following immunization with myelin, these monkeys develop a chronic, relapsing-remitting form of experimental allergic encephalomyelitis (EAE), which pathologically recapitulates the hallmark features of lesions of human MS. The MS-like lesion in C. jacchus results from a complex immune response against myelin antigens and requires both T cells and pathogenic antibodies. Studies of C. jacchus EAE have permitted the identification of a major target for pathogenic autoantibodies in MS, the myelin/oligodendrocyte glycoprotein. Other advantages of the model include a natural bone-marrow chimerism, which permits T-cell adoptive transfers between siblings, and the possibility of using different antigens to produce either inflammatory or demyelinating phenotypes of EAE. Despite their small size, sequential in vivo imaging and immunological studies are possible in these monkeys, and have been used to monitor efficacy in preclinical trials. Due to close phylogeny and high homology of immune and nervous system genes with humans, this model should fast-track the development of novel therapeutics for MS.
Animals↗
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.
Animals↗
Specific immunotherapy: one size does not fit all.
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Clinical Trials as Topic↗
Autoreactivity to myelin antigens: myelin/oligodendrocyte glycoprotein is a prevalent autoantigen.
Autoreactive T cells specific for myelin antigens are thought to play a role in the pathogenesis of multiple sclerosis (MS). We compared T cell proliferative responses in peripheral blood following challenge in vitro with myelin/oligodendrocyte glycoprotein (recombinant protein, rMOG), myelin basic protein (MBP) and proteolipid apoprotein (PLP) in 50 patients with MS and 40 healthy controls. T cell reactivity against rMOG (defined by a specific stimulation index of 2.5 or greater) was present in 13 (26%) MS patients and 12 (30%) healthy controls and was MHC-restricted, as anti-MHC class II antibodies abolished all proliferative responses. By contrast, reactivity against PLP was present in only one (2%) MS patient and six (15%) controls, and no reactivity against MBP was found in any subject. Thus, by the criteria of the present study, an increased reactivity of circulating T cells to MOG is present to a similar degree in healthy individuals and in patients with MS. This finding raises the possibility that additional factors contribute to the pathogenicity of these autoreactive T cell populations in demyelinating disorders of the central nervous system.
Adult↗
Determinant spreading associated with demyelination in a nonhuman primate model of multiple sclerosis.
Definition of the immune process that causes demyelination in multiple sclerosis is essential to determine the feasibility of Ag-directed immunotherapy. Using the nonhuman primate, Callithrix jacchus jacchus (common marmoset), we show that immunization with myelin basic protein and proteolipid protein determinants results in clinical disease with significant demyelination. Demyelination was associated with spreading to myelin oligodendrocyte glycoprotein (MOG) determinants that generated anti-MOG serum Abs and Ig deposition in central nervous system white matter lesions. These data associate intermolecular "determinant spreading" with clinical autoimmune disease in primates and raise important issues for the pathogenesis and treatment of multiple sclerosis.
Adjuvants, Immunologic↗
Demyelination in primate autoimmune encephalomyelitis and acute multiple sclerosis lesions: a case for antigen-specific antibody mediation.
Neuropathological and ultrastructural features of central nervous system demyelination were compared in marmoset experimental autoimmune encephalomyelitis (EAE) induced with myelin/oligodendrocyte glycoprotein (MOG), and in 3 cases of multiple sclerosis (MS) displaying recent lesions. At the edges of EAE and MS lesions, a zone of myelin vacuolation was common, whereas in the lesion proper, myelin sheaths were consistently transformed into vesiculated membranous networks. These networks became dissociated from axons by cell processes from macrophages. Oligodendrocytes were remarkably spared and evidence of myelin repair was present but not prominent. Axonal pathology was more common in the MS material than in marmoset EAE. Immunocytochemistry, using gold-labeled encephalitogenic peptides of MOG and silver enhancement to detect MOG autoantibodies, revealed the presence of MOG-specific autoantibodies over vesiculated myelin networks. Gold-labeled antibody to IgG also gave a positive reaction. Gold-labeled peptide of myelin basic protein did not react with MOG/EAE tissue, but the same conjugate gave positive staining in MS (and in marmoset EAE induced by whole white matter), perhaps indicating broader spectrum immunoreactivity or sensitization to myelin antigens. Thus, vesicular disruption of myelin was a constant feature in these evolving, highly active lesions in primate EAE and MS and appeared causally related to the deposition of antigen-specific autoantibodies.
Adolescent↗
Identification of autoantibodies associated with myelin damage in multiple sclerosis.
The molecular mechanisms underlying myelin sheath destruction in multiple sclerosis lesions remain unresolved. With immunogold-labeled peptides of myelin antigens and high-resolution microscopy, techniques that can detect antigen-specific antibodies in situ, we have identified autoantibodies specific for the central nervous system myelin antigen myelin/oligodendrocyte glycoprotein. These autoantibodies were specifically bound to disintegrating myelin around axons in lesions of acute multiple sclerosis and the marmoset model of allergic encephalomyelitis. These findings represent direct evidence that autoantibodies against a specific myelin protein mediate target membrane damage in central nervous system demyelinating disease.
Animals↗
Characterization of the TCRB chain repertoire in the New World monkey Callithrix jacchus.
Callithrix jacchus is an outbred New World primate characterized by a naturally occurring bone marrow chimerism, restricted polymorphism at many MHC loci, and unusual susceptibility to viral pathogens, adenocarcinoma, colitis, and, following immunization with myelin antigens, a demyelinating disease of the central nervous system closely resembling human multiple sclerosis. Here we characterize the TCRB repertoire in this species, representing the first such analysis in a New World monkey. Two TCRBC, 13 BJ, 2 BD, and 15 BV genes were identified. Overall, a high degree of similarity with human TCRBV-D-J-C gene sequences was observed, indicating a close phylogenetic relationship. Biased usage in favor of genes from the TCRBC1-BJ1 cluster was present in 77% of sequences, in contrast to preferential usage of BC2-BJ2 genes known to occur in humans and mice. Complementarity-determining region 3 averaged 10 amino acids in length and were diverse. Framework regions of TCRBV genes were extensively conserved. Phylogenetic analysis of TCRBV sequences from different species indicated that TCR genes are highly stable across primates. Thus, a diverse TCRB repertoire is generated in C. jacchus despite the limited polymorphism of class I MHC loci. Extensive homology to human TCR genes, natural chimerism, and susceptibility to inflammatory disorders are characteristics of C. jacchus that create a useful model system for the study of human autoimmunity.
Amino Acid Sequence↗
Creation of a model for multiple sclerosis in Callithrix jacchus marmosets.
Multiple sclerosis (MS) is an inflammatory disease of the CNS white matter characterized pathologically by the accumulation of perivascular and parenchymal T lymphocytes (T cells), and macrophage infiltration associated with myelin destruction. MS lesions are also characterized by the death of oligodendrocytes (the myelin-producing cells) and proliferation and hypertrophy of astrocytes with scar tissue (gliosis) replacing normal myelin. These changes result in the loss of axonal conduction for neurons of the CNS and in clinical disability. MS is thought to be an autoimmune disease, in particular because of its analogy with the disease model of experimental allergic encephalomyelitis (EAE). Despite extensive research and the availability of various EAE models in laboratory rodents the etiology of human MS has not been identified, and to date no effective treatment exists. Phylogenetic differences may limit the usefulness of existing EAE models, and indeed no single form of rodent EAE recapitulates all the clinical and pathological features of MS. Here we describe a novel form of EAE created in a nonhuman primate, the common marmoset Callithrix jacchus. Active immunization of these monkeys with whole myelin produces a primary demyelinating disease with a chronic relapsing-remitting course, characterized pathologically by moderate inflammation with prominent and early demyelination and gliosis reminiscent of human MS. Adoptive and passive transfer experiments have permitted definition of the mechanisms responsible for the MS-like pathology. Production of the fully demyelinated lesion requires synergism between encephalitogenic (e.g., disease-inducing) T cells and pathogenic antibody. The antigens of myelin that promote encephalitogenic T cell and antibody responses in this system have been identified. Because of the similarity between the two conditions and the high degree of conservation in immune and nervous system genes between nonhuman primates and humans, future studies of marmoset EAE will likely accelerate the development of therapies for human MS.
Adoptive Transfer↗
Inhibition of allergic encephalomyelitis in marmosets by vaccination with recombinant vaccinia virus encoding for myelin basic protein.
A primary demyelinating form of experimental allergic encephalomyelitis (EAE) resembling human multiple sclerosis (MS) occurs in Callithrix jacchus marmosets following immunization with human white matter. Participation of a T-cell immune response against myelin basic protein (MBP) in this disease model is supported by observations of increased reactivity against MBP in PBMC and of adoptive transfer of an inflammatory form of EAE by MBP-reactive T-cells. To evaluate the effects of ectopic presentation of MBP on marmoset EAE, animals were vaccinated prior to induction of EAE by subcutaneous injection of attenuated strains of vaccinia virus genetically engineered to contain either the entire coding sequence for human MBP (vT15) or the equine herpes virus glycoprotein gH gene (vAbT249). Vaccination with vT15 was followed by transient cytoplasmic and surface membrane expression of MBP in circulating PBMC (15-45 days). The onset of clinical EAE after immunization (pi) was markedly delayed in vT15-vaccinated animals (37-97 days pi, n = 4) compared to vAbT249-vaccinated controls (14-18 days pi, n = 3). Proliferative responses against MBP but not against vaccinia antigens or phytohemagglutinin were suppressed in protected animals. Thus, development of attenuated live viruses carrying genes for myelin antigens could be useful for induction of immunologic tolerance and for modulation of autoimmune demyelination.
Animals↗