myelin-basic-protein and Myasthenia-Gravis

Copolymer 1 (Cop 1, Copaxone) is a synthetic amino acid copolymer effective in suppression of experimental allergic encephalomyelitis (EAE). The suppressive effect of Cop 1 in EAE is not restricted to a certain species, disease type or encephalitogen used for EAE induction. In phase II and III clinical trials, Cop 1 was found to slow the progression of disability and reduce the relapse rate in exacerbating-remitting multiple sclerosis (MS) patients. In vivo and in vitro studies suggest that the mechanism for Cop 1 activity in EAE and MS involves, as an initial step, the binding of Cop 1 to MHC class II molecules. This binding results in competition with myelin antigens for T-cell activation, both at the MHC and T-cell receptor levels and in induction of specific suppressor cells of the Th2 type. As an antigen-specific intervention, Cop 1 has the advantage of reduced probability for long-term damage to the immune system, and is thus a safe and effective novel therapeutic approach to MS. It also serves to illustrate the new concept of a drug/vaccine specific for a single autoimmune disease. Indeed, we have used a similar approach for myasthenia gravis. Myasthenia gravis (MG) and its experimental animal model, experimental autoimmune MG (EAMG), are immune disorders characterized by circulating antibodies and lymphocyte autoreactivity to nicotinic acetylcholine receptor (AChR). We utilized peptides representing different sequences of the human acetylcholine receptor alpha-subunit to study the role of T cells in the initiation, development and immunomodulation of myasthenia gravis. Here we summarize our studies over the last decade on T cells specific to 'myasthenogenic' epitopes of the alpha-subunit of the human acetylcholine receptor and their relevance for myasthenia gravis.

Topics: Animals; Autoimmune Diseases; Encephalomyelitis, Autoimmune, Experimental; Glatiramer Acetate; Humans; Immunosuppressive Agents; Multiple Sclerosis; Myasthenia Gravis; Myelin Basic Protein; Peptides; Vaccines

The major immune-mediated diseases affecting the nervous system are reviewed. The continued expansion of knowledge concerning the pathogenesis is leading to improved diagnosis and effective treatment regimens.

Topics: Adrenal Cortex Hormones; Antibodies, Monoclonal; Cholinesterase Inhibitors; Humans; Hypergammaglobulinemia; Immune System Diseases; Immunoglobulins; Immunosuppression Therapy; Multiple Sclerosis; Myasthenia Gravis; Myelin Basic Protein; Nervous System Diseases; Plasma Exchange; Plasmapheresis; Polyradiculoneuropathy; Receptors, Cholinergic

Topics: alpha-Fetoproteins; Animals; Antibody Formation; Autoimmune Diseases; Disease Models, Animal; Encephalomyelitis, Autoimmune, Experimental; Guinea Pigs; Lymphocyte Activation; Myasthenia Gravis; Myelin Basic Protein; Rabbits; Rats; Receptors, Cholinergic; Torpedo

Oral tolerization with acetylcholine receptor (AChR) and myelin basic protein (MBP) prior to immunization with AChR+MBP+ complete Freund's adjuvant (CFA) alleviated clinical signs of experimental autoimmune myasthenia gravis (EAMG)+experimental allergic encephalomyelitis (EAE) and AChR- or MBP-specific T and B cell responses. Tolerance induced via the nasal route needs much less tolerogen and may still be as effective as oral tolerance induction. We now immunized Lewis rats with AChR+MBP+bovine peripheral nerve myelin (BPM)+CFA, which resulted in a multiphasic clinical picture with a combination of clinical signs of the EAMG+EAE+experimental allergic neuritis (EAN), accompanied by massive macrophage infiltrations in sections of muscle, spinal cord and sciatic nerve, and strong T and B cell responses to AChR, MBP and BPM in lymphoid organs. Nasal administration of microg doses of AChR+MBP+BPM prior to immunization with a mixture of these antigens+CFA effectively suppressed the incidence and severity of clinical disease, reduced macrophage infiltrations in sections of muscle, spinal cord and sciatic nerve, and down-regulated autoreactive T cell responses to the three antigens in lymphoid organs. Numbers of AChR-, MBP-, BPM-reactive Th1 type of cytokine interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha mRNA expression in lymph node cells were markedly suppressed, while transforming growth factor-beta (TGF-beta) mRNA expression was upregulated from nasally tolerized rats, suggesting an active suppression mechanism may act partly in the induction of tolerance. The results implicate the possibility to establish multiple autoantigen-based vaccination for the prevention of autoimmune diseases in humans.

Topics: Administration, Intranasal; Animals; Autoantigens; Autoimmune Diseases; Cattle; Encephalomyelitis, Autoimmune, Experimental; Epitopes; Female; Immune Tolerance; Immunoglobulin G; Immunohistochemistry; Immunosuppressive Agents; Interferon-gamma; Interleukin-10; Leukocytes, Mononuclear; Muscle Weakness; Myasthenia Gravis; Myelin Basic Protein; Myelin Sheath; Neuritis, Autoimmune, Experimental; Rats; Rats, Inbred Lew; Receptors, Cholinergic; RNA, Messenger; T-Lymphocytes; Transforming Growth Factor beta; Tumor Necrosis Factor-alpha

Nasal administration of nicotinic acetylcholine receptor (AChR) to Lewis rats prior to myasthenogenic immunization with AChR plus Freund's complete adjuvant (FCA) resulted in prevention or marked decrease of the severity of EAMG, suppression of AChR-specific B cell responses and of AChR-reactive T cell functions. To examine the involvement of immunoregulatory cytokines and the underlying mechanisms involved in tolerance induction, in situ hybridization with radio-labelled synthetic oligonucleotide probes was adopted to enumerate mononuclear cells (MNC) expressing mRNA for the proinflammatory cytokine IFN-gamma, the B cell stimulating IL-4 and the immune response-down-regulating TGF-beta. Popliteal and inguinal lymph nodes from EAMG rats contained elevated numbers of AChR-reactive IFN-gamma, IL-4 and TGF-beta mRNA-expressing cells compared with control rats receiving PBS nasally and injected with FCA only. Nasal tolerance to EAMG was accompanied by decreased numbers of AChR-reactive IFN-gamma and IL-4 mRNA-expressing cells, and strong up-regulation of TGF-beta mRNA-positive cells in lymphoid organs compared with non-tolerized EAMG control rats. The relative affinity of anti-AChR antibodies was lower, but muscle AChR amounts were higher in nasally tolerized rats compared with non-tolerized EAMG control rats. The results suggest that IFN-gamma and IL-4 are central effector molecules in the development of EAMG, and that TGF-beta plays an important role in tolerance induction to EAMG.

Topics: Administration, Intranasal; Animals; Concanavalin A; DNA Probes; Electrophoresis, Polyacrylamide Gel; Female; Immune Tolerance; Immunoglobulin G; In Situ Hybridization; Interferon-gamma; Interleukin-4; Leukocytes, Mononuclear; Lymph Nodes; Muscles; Myasthenia Gravis; Myelin Basic Protein; Oligonucleotides; Rats; Rats, Inbred Lew; Receptors, Nicotinic; RNA, Messenger; Transforming Growth Factor beta; Up-Regulation; Vaccination

Multiple sclerosis (MS) is associated with high levels of circulating T lymphocytes that respond to the myelin antigens myelin basic protein (MBP) and proteolipid protein (PLP) by producing various cytokines including interferon-gamma (IFN-gamma) that makes MS worse and transforming growth factor-beta (TGF-beta), an endogenously produced immunosuppressant that might act beneficially. To further define the role of TGF-beta in MS, we examined the effects of recombinant TGF-beta 1 (rTGF-beta 1) on autoantigen-mediated regulation of cytokines in MS and myasthenia gravis (MG). Blood mononuclear cells (MNC) were cultivated with or without rTGF-beta 1, and with or without autoantigen or the recall antigen PPD. MNC expressing cytokine mRNA were detected after in situ hybridization with radiolabeled cDNA oligonucleotide probes. Femtogram concentrations of rTGF-beta 1 suppressed MBP-, PLP- and PPD-induced upregulation of IFN-gamma, IL-4, IL-6, tumor necrosis factor-alpha (TNF-alpha), TNF-beta and perforin in MS, and acetylcholine receptor (AChR)-induced augmentation of these pro-inflammatory cytokines in MG, but had no effects on autoantigen- or PPD-induced expression of IL-10 or TGF-beta itself. rTGF-beta 1 also suppressed numbers of myelin antigen-reactive IFN-gamma- and IL-4-secreting cells in MS and AChR-reactive IFN-gamma and IL-4 secreting cells in MG. The selective suppressive effects of TGF-beta 1 on autoantigen-induced upregulation of pro-inflammatory cytokines makes TGF-beta 1 attractive as a treatment alternative in MS and MG.

Topics: Adult; Aged; Autoantigens; Cells, Cultured; Cytokines; Female; Gene Expression; Humans; In Situ Hybridization; Inflammation; Interferon-gamma; Interleukin-10; Interleukin-4; Leukocytes, Mononuclear; Male; Middle Aged; Multiple Sclerosis; Myasthenia Gravis; Myelin Basic Protein; Oligonucleotide Probes; Recombinant Proteins; RNA, Messenger; Transforming Growth Factor beta

Experimental autoimmune myasthenia gravis (EAMG) is a well established animal model, which can be induced in various animal species and strains with acetylcholine receptor (AChR) and represents an experimental counterpart of human myasthenia gravis (MG). Current immunotherapies of both EAMG and MG are non-specific and limited by their toxicity. Tolerance to EAMG has been achieved by oral administration of milligram quantities of Torpedo AChR. In the present report we demonstrate that nasal administration of microgram doses of Torpedo AChR to female Lewis rats prior to immunization with Torpedo AChR and complete Freund's adjuvant resulted in the prevention of subsequently induced EAMG, the suppression of serum anti-AChR antibody levels, the decrease of delayed-type hypersensitivity responses to AChR, as well as the suppression of AChR-specific immunoglobulin G-secreting cells, AChR-reactive interferon-gamma-secreting cells and T cell proliferation in peripheral lymphoid organs, particularly in popliteal and inguinal lymph nodes regional to immunization. We conclude that clinical signs of EAMG can be efficiently prevented by nasal administration of AChR in parallel with the downregulation of both B and T cell responses specific to AChR.

Topics: Administration, Intranasal; Animals; Concanavalin A; Electric Organ; Enzyme-Linked Immunosorbent Assay; Female; Hypersensitivity, Delayed; Immunoglobulin G; Interferon-gamma; Lymphocyte Activation; Myasthenia Gravis; Myelin Basic Protein; Rats; Rats, Inbred Lew; Receptors, Cholinergic; Time Factors; Torpedo

Oral administration of acetylcholine receptor (AChR) to Lewis rats prior to myasthenogenic immunization with AChR and complete Freund's adjuvant (CFA) results in the prevention of experimental autoimmune myasthenia gravis (EAMG), and decreased serum levels of anti-AChR antibodies. Using an ELISPOT assay, we have now determined numbers of cells in the popliteal, inguinal and mesenteric lymph nodes, spleen and thymus secreting anti-AChR IgG antibodies. Except for mesenteric lymph nodes, a marked diminution of such cells was detected in these lymphoid organs in rats orally tolerized with AChR compared to buffer-fed or vehicle-fed control rats with EAMG. Of note is that, after AChR feeding, the B cell response to AChR in thymus was diminished to the same low level as in CFA-injected, buffer-fed control rats. The relative affinity of serum anti-AChR IgG antibodies measured by KSCN-ELISA was lower in the orally tolerized rats compared to buffer-fed or vehicle-fed rats. The observations showed that oral administration of AChR, besides preventing clinical EAMG, also counteracts the development of AChR-specific B cells, especially those with high affinity antibody production, in most lymphoid organs.

Topics: Administration, Oral; Animals; Antibody Affinity; Autoantibodies; Autoimmune Diseases; B-Lymphocytes; Buffers; Encephalomyelitis, Autoimmune, Experimental; Female; Freund's Adjuvant; Immune Tolerance; Immunization; Immunoglobulin G; Lymph Nodes; Lymphoid Tissue; Myasthenia Gravis; Myelin Basic Protein; Pharmaceutical Vehicles; Rats; Rats, Inbred Lew; Receptors, Cholinergic; Thymus Gland; Torpedo

Oral administration of acetylcholine receptor (AChR) or myelin basic protein (MBP) to Lewis rat prior to immunization with AChr or MBP and complete Freund's adjuvant (CFA) has previously been shown to prevent or delay the onset of experimental autoimmune myasthenia gravis (EAMG) or experimental allergic encephalomyelitis (EAE), which represent animal models of myasthenia gravis and multiple sclerosis, respectively. Here we show that Lewis rats immunized with AChr+MBP+CFA developed both signs of muscular weakness seen in EAMG and paresis characteristic for EAE. This disease was associated with high levels of anti-AChR and anti-MBP antibody secreting cells and of AChR- and MBP-reactive INF-gamma secreting Th1-like cells in lymph nodes. The diseased rats also showed upregulation of AChR- and MBP-induced mRNA expression of IFN-gamma in lymph node cells. Oral tolerization with AChR and MBP in combination prior to immunization with AChR+MBP+CFA alleviated clinical disease as well as AChR- and MBP-specific B cell node cells. The results implicate that oral tolerization simultaneously to more than one autoimmune disease-related autoantigen is feasible, and that suppression of autoantigen-induced IFN-gamma and augmentation of TGF-beta are pivotal in tolerance induction.

Topics: Administration, Oral; Animals; Encephalomyelitis, Autoimmune, Experimental; Female; Immune Tolerance; Interferon-gamma; Interleukin-4; Myasthenia Gravis; Myelin Basic Protein; Rats; Rats, Inbred Lew; Receptors, Cholinergic; RNA, Messenger; Transforming Growth Factor beta

T cells recognizing the myelin components myelin basic protein (MBP) and proteolipid protein (PLP) are increased in multiple sclerosis (MS), and there are elevated numbers of T cells recognizing the nicotinic acetylcholine receptor (AChR) in myasthenia gravis (MG). However, the cytokine repertoires in these diseases are largely unknown. We adopted in situ hybridization with radiolabeled complementary DNA oligonucleotide probes to enumerate mononuclear cells that expressed the T-helper type 1 (Th1) cell-related interferon-gamma (IFN-gamma) and Th2-associated interleukin-4 (IL-4) after short-term culture in the presence of autoantigen. High numbers of IFN-gamma and IL-4 mRNA-expressing cells in response to MBP and PLP were detected in patients with untreated MS, and to AChR in MG. The levels of IFN-gamma and IL-4 mRNA-positive cells in MS after culture in the presence of AChR, and in MG after culture in the presence of MBP or PLP, did not differ from those detected after culture without antigen. The CSF of MS patients contained four- to eightfold more myelin protein-reactive IFN-gamma and IL-4 expressing cells. The findings imply that MS and MG are associated with mixed Th1- and Th2-like cell responses directed to organ-specific target antigens.

Topics: Adult; Autoantigens; Epitopes; Female; Gene Expression; Humans; Interferon-gamma; Interleukin-4; Male; Middle Aged; Monocytes; Multiple Sclerosis; Myasthenia Gravis; Myelin Basic Protein; Myelin Proteins; Myelin Proteolipid Protein; Receptors, Cholinergic; RNA, Messenger

Oral administration of nicotinic acetylcholine receptor (AChR) to Lewis rats prior to myasthenogenic immunization with Torpedo AChR+complete Freund's adjuvant (CFA) results in the prevention of experimental autoimmune myasthenia gravis (EAMG) and the suppression of AChR-specific B cell responses and counteracts the development of AChR-reactive interferon-gamma (IFN-gamma) secreting T cells. To study the involvement of the T helper type 1 (Th1) cell-related lymphokine IFN-gamma, the Th2 cell-related interleukin-4 (IL-4), and transforming growth factor beta (TGF-beta) that suppresses the synthesis of IFN-gamma and IL-4, we used in situ hybridization with complementary DNA oligonucleotide probes to enumerate mononuclear cells (MNC) expressing mRNA for the cytokines IFN-gamma, IL-4, and TGF-beta. Upon in vivo recognition of AChR, popliteal, inguinal, and mesenteric lymph nodes, spleen and thymus of rats with EAMG contained higher levels of IFN-gamma, IL-4, and TGF-beta mRNA-expressing cells compared to CFA-injected control rats, implicating the involvement in EAMG of AChR-reactive Th1 and Th2 cells in parallel. TGF-beta was also upregulated in EAMG. Oral tolerance to EAMG was characterized by suppression of the levels of MNC expressing IFN-gamma and IL-4, but augmentation of cells expressing TGF-beta. The results suggest that IFN-gamma, IL-4, and TGF-beta are involved in the development of EAMG, and that TGF-beta is important in the induction of oral tolerance to EAMG.

Topics: Animals; Gene Expression; Immune Tolerance; Interferon-gamma; Interleukin-4; Lymphoid Tissue; Myasthenia Gravis; Myelin Basic Protein; Rats; Rats, Inbred Lew; Receptors, Nicotinic; RNA, Messenger; T-Lymphocytes, Helper-Inducer; Time Factors; Tissue Distribution; Transforming Growth Factor beta

Antibodies against the nicotinic acetylcholine receptor (AChR) of the neuromuscular junction are detectable in most patients with myasthenia gravis (MG) and assumed to participate in the destruction of the AChR, thereby, causing the characteristics signs and symptoms of the disease. The extent and importance of T cell responses to AChR and its subunits in MG are still unsettled. We have now examined T cell reactivities using human recombinant AChR-alpha subunit as antigen. Upon recognition of appropriate antigen in an MHC-class II-restricted fashion, memory T cells secrete interferon-gamma (IFN-gamma). Adopting this principle in an immunospot assay we found that 73% of MG patients had recombinant human AChR-alpha subunit-reactive T cells at a median value of 1 per 56,000 blood mononuclear cells, while only 27% of the MG patients responded to the alpha subunit in a conventional lymphocyte proliferation assay. This compares with even lower numbers of AChR-reactive T cells and 14% positivity in the proliferation assay among control subjects. The T cell responses to the control antigens purified protein derivative and myelin basic protein did not differ between MG and controls, underlining the specificity of an augmented T cell reactivity to AChR-alpha subunit in MG. Alpha Subunit-specific T cell lines and clones propagated from patients with MG and healthy controls yielded a high proportion of alpha subunit-reactive T cells in the IFN-gamma immunospot assay. Their appearance was inhibited by the addition of monoclonal anti-MHC class II antibodies, demonstrating that an MHC-restricted T cell response was measured. Our data underline that the AChR-alpha subunit is a major T cell autoantigen in MG.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Antibody Specificity; Cell Division; Female; Humans; Immunity, Cellular; Interferon-gamma; Male; Middle Aged; Myasthenia Gravis; Myelin Basic Protein; Nervous System Diseases; Phytohemagglutinins; Receptors, Cholinergic; Recombinant Proteins; T-Lymphocytes; Tuberculin

Anti-myelin antibodies can be found in sera from patients with neurologic disorders of suspected immune-mediated pathogenesis such as multiple sclerosis and inflammatory polyneuropathies. However, the specificity of these findings is controversial. In the present study, in vitro synthesis of antibodies to myelin components was compared to their presence in sera in diverse neurological disorders. Epstein-Barr virus was used to activate B lymphocytes for in vitro antibody production. Anti-myelin basic protein and anti-galactocerebroside antibodies were secreted in vitro by B lymphocytes derived from patients with neurological disorders of various etiologies and pathogenetic mechanisms. Anti-myelin basic protein antibodies were detected in many more cell culture supernatants than in sera from the same patients. In vitro secretion of antibodies to myelin antigens, as well as the presence of these antibodies in body fluids, are apparently non-specific for disease type and may be secondary to neural tissue damage.

Topics: Aged; Aged, 80 and over; Antibody Formation; Antigens, Viral; B-Lymphocytes; Branchial Region; Facial Paralysis; Female; Galactosylceramides; Herpesvirus 4, Human; Humans; Lymphocyte Activation; Male; Myasthenia Gravis; Myelin Basic Protein; Myelin Sheath; Nervous System Diseases; Neuritis; Radioimmunoassay

The development of experimental autoimmune encephalomyelitis (EAE) was prevented in rats immunized with encephalitogenic antigen two weeks, but not twelve weeks, after stereotaxic electrolytic destruction of the anterior hypothalamus. Serum antibody level to the antigen myelin basic protein was decreased, and in vitro lymphocyte transformation response to a mitogen was increased. On the other hand, incidence and intensity of chronic experimental autoimmune myasthenia gravis (EAMG) induced by acetylcholine receptor immunization were higher in rats with anterior hypothalamic lesion. In addition, expression of EAE in rats was inhibited when dopamine and norepinephrine in brain were depleted due to intraventricular injection of 6-hydroxydopamine or subcutaneous injection of reserpine. The study indicates hypothalamic modulatory effects on autoimmune response as well as possible involvement of neurotransmitters in this kind of neuroimmunomodulation.

Topics: Animals; Autoantibodies; Encephalomyelitis, Autoimmune, Experimental; Female; Hypothalamus, Anterior; Lymphocyte Activation; Myasthenia Gravis; Myelin Basic Protein; Rats; Rats, Inbred Lew; Receptors, Cholinergic

The thymus glands which were excised for therapy (myasthenia gravis; MG) or experimental therapy (multiple sclerosis; MS) were compared to thymic biopsies from patients undergoing cardiac surgery. There was no difference in the weight or total cells of MG and MS thymuses or of the cell density of control, of MG or MS glands. Only 1 of 25 MS thymuses was hyperplastic, as were 2 of 9 of the MG thymuses and none of the controls. Several differences were noted for thymic lymphocyte proliferation to mitogenes in MS patients and to antigens in MS and MG patients. Ms thymuses had a decreased stimulation index to antithymocyte globulin and to optimal concentrations of pokeweed mitogen. Myasthenia gravis thymuses showed a significantly increased stimulation of myelin basic protein. The % B and % T cell counts were normal for the MS patients. No differences were noted in the incidence of mixed lymphocyte reactions between thymocytes and peripheral lymphocytes in the three groups. Fresh thymic lymphocytes did not suppress concanavalin A stimulated lymphocyte proliferation. It is not known if the differences in lymphocyte proliferation between MS, MG, and control thymuses represent a primary or secondary change.

Topics: Adult; Humans; Lymphocyte Activation; Lymphocyte Culture Test, Mixed; Middle Aged; Multiple Sclerosis; Myasthenia Gravis; Myelin Basic Protein; Organ Size; Streptodornase and Streptokinase; T-Lymphocytes; Thymectomy; Thymus Gland; Thymus Hyperplasia

Topics: Anemia, Hemolytic, Autoimmune; Autoimmune Diseases; Disease Models, Animal; Humans; Immune Tolerance; Immunity, Cellular; Lymphocyte Cooperation; Macrophages; Myasthenia Gravis; Myelin Basic Protein; T-Lymphocytes; Thyroiditis

The macrophage migration inhibition factor (MIF) assay and a counterimmunodiffusion assay were utilized to measure immune responses to human myelin basic protein in 75 patients with multiple sclerosis (MS) and in 120 control subjects. Eight out of ten MS patients in acute exacerbation and one out of seventeen convalescent, but none of chronically ill MS patients gave positive results in the MIF test. Forty-six percent of the patients with negative MIF assays but only 22% of those with positive assays had positive antibody results. In the counterimmunodiffusion assay, myelin basic protein antibody was demonstrated in almost 2/3 of patients during convalescence but it was not present in those whose illness had been stable for 6 months or longer. While no correlation with the stage or duration of the illness was present in other disorders, in MS an inverse correlation with clinical activity and in vitro evidence of cellular sensitization to encephalitogenic basic protein was apparent.

Topics: Autoantibodies; Central Nervous System Diseases; Encephalitis; Humans; Immunity, Cellular; Macrophage Migration-Inhibitory Factors; Multiple Sclerosis; Myasthenia Gravis; Myelin Basic Protein; Peripheral Nervous System Diseases

Topics: Animals; Antigens, Neoplasm; Asthma; Cell Migration Inhibition; Diagnostic Errors; Electrophoresis; Female; Guinea Pigs; Humans; Influenza, Human; Leukemia; Lymphocytes; Macrophages; Male; Multiple Sclerosis; Myasthenia Gravis; Myelin Basic Protein; Neoplasm Proteins; Neoplasms; Sarcoidosis