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Oshima M, Iida-Klein A, Maruta T, Deitiker PR, Atassi MZ. Decreased bone mineral density in experimental myasthenia gravis in C57BL/6 mice. Autoimmunity 2017; 50:346-353. [PMID: 28850269 DOI: 10.1080/08916934.2017.1367772] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Experimental autoimmune myasthenia gravis (EAMG), an animal model of myasthenia gravis (MG), can be induced in C57BL/6 (B6, H-2 b) mice by 2-3 injections with Torpedo californica AChR (tAChR) in complete Freund's adjuvant. Some EAMG mice exhibit weight loss with muscle weakness. The loss in body weight, which is closely associated with bone structure, is particularly evident in EAMG mice with severe muscle weakness. However, the relationship between muscle weakness and bone loss in EAMG has not been studied before. Recent investigations on bone have shed light on association of bone health and immunological states. It is possible that muscle weakness in EAMG developed by anti-tAChR immune responses might accompany bone loss. We determined whether reduced muscle strength associates with decreased bone mineral density (BMD) in EAMG mice. EAMG was induced by two injections at 4-week interval of tAChR and adjuvants in two different age groups. The first tAChR injection was either at age 8 weeks or at 15 weeks. We measured BMD at three skeletal sites, including femur, tibia, and lumbar vertebrae, using dual energy X-ray absorptiometry. Among these bone areas, femur of EAMG mice in both age groups showed a significant decrease in BMD compared to control adjuvant-injected and to non-immunized mice. Reduction in BMD in induced EAMG at a later-age appears to parallel the severity of the disease. The results indicate that anti-tAChR autoimmune response alone can reduce bone density in EAMG mice. BMD reduction was also observed in adjuvant-injected mice in comparison to normal un-injected mice, suggesting that BMD decrease can occur even when muscle activity is normal. Decreased BMD observed in both tAChR-injected and adjuvant-injected mice groups were discussed in relation to innate immunity and bone-related immunology involving activated T cells and tumour necrosis factor-related cytokines that trigger osteoclastogenesis and bone loss.
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Affiliation(s)
- Minako Oshima
- a Department of Biochemistry and Molecular Biology , Baylor College of Medicine , Houston , TX , USA
| | - Akiko Iida-Klein
- b Regional Bone Center , Helen Hayes Hospital , West Haverstraw , NY , USA.,c Department of Clinical Pathology , Columbia University College of Physicians and Surgeons , New York , NY , USA
| | - Takahiro Maruta
- a Department of Biochemistry and Molecular Biology , Baylor College of Medicine , Houston , TX , USA
| | - Philip R Deitiker
- a Department of Biochemistry and Molecular Biology , Baylor College of Medicine , Houston , TX , USA
| | - M Zouhair Atassi
- a Department of Biochemistry and Molecular Biology , Baylor College of Medicine , Houston , TX , USA.,d Department of Pathology and Immunology , Baylor College of Medicine , Houston , TX , USA
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Maruta T, Oshima M, Mosier DR, Atassi MZ. Injection of inactiveBordetella pertussisand complete Freund’s adjuvant withTorpedo californicaAChR increases the occurrence of experimental autoimmune myasthenia gravis in C57BL/6 mice. Autoimmunity 2017; 50:293-305. [DOI: 10.1080/08916934.2017.1329831] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Takahiro Maruta
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Minako Oshima
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Dennis R. Mosier
- Department of Neurology, Baylor College of Medicine, Houston, TX, USA
| | - M. Zouhair Atassi
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, USA
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3
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Oshima M, Deitiker P, Jankovic J, Aoki KR, Atassi MZ. Submolecular recognition of the C-terminal domain of the heavy chain of botulinum neurotoxin type A by T cells from toxin-treated cervical dystonia patients. Immunobiology 2015; 221:568-76. [PMID: 26701846 DOI: 10.1016/j.imbio.2015.12.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 12/04/2015] [Accepted: 12/06/2015] [Indexed: 10/22/2022]
Abstract
We determined the T-cell proliferative responses of the peripheral blood lymphocytes (PBL) from 25 botulinum neurotoxin (BoNT)-treated patients to 31 overlapping synthetic peptides encompassing the C-terminal half (residues 855-1296) of BoNT/A heavy chain. Responses of PBL to HC peptides varied among patients. Samples from 14 patients treated solely with BoNT/A recognized 2-13 (average 6.4) peptides/sample at Z>3.0 level. Six peptide regions representing residues 855-873, 1023-1041, 1051-1069, 1093-1111, 1135-1153 and 1247-1265 were frequently recognized by 36-57% of these PBLs. Influence of treatment parameters on T-cell recognition of the peptides was also investigated.
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Affiliation(s)
- Minako Oshima
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Philip Deitiker
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Joseph Jankovic
- Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
| | | | - M Zouhair Atassi
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA; Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX 77030, USA.
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4
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Regions recognized on the light chain of botulinum neurotoxin type A by T lymphocytes of SJL and BALB/c mice primed with inactivated toxin. Immunobiology 2014; 219:950-7. [DOI: 10.1016/j.imbio.2014.07.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 07/29/2014] [Indexed: 11/17/2022]
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Human T-cell responses to botulinum neurotoxin: proliferative responses in vitro of lymphocytes from botulinum neurotoxin A-treated movement disorder patients. J Neuroimmunol 2011; 237:66-72. [PMID: 21737146 DOI: 10.1016/j.jneuroim.2011.06.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Revised: 05/25/2011] [Accepted: 06/10/2011] [Indexed: 11/23/2022]
Abstract
We determined the T-cell responses against botulinum neurotoxin type A (BoNT/A) and tetanus toxin (TeNT) of peripheral blood lymphocytes from 95 BoNT-treated patients and 63 non-treated control subjects. The patient group included 80 cervical dystonia and 15 other movement disorder cases. Positive T-cell responses to BoNT/A were detected in 70% of the treated patients, and in only 3% of controls. T-cell responses of BoNT-treated patients against BoNT/A did not differ between patients who were clinically responsive and those who had become non-responsive to the treatment. BoNT-treated patients gave significantly higher in vitro T-cell responses to TeNT than did the controls.
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6
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Deitiker PR, Oshima M, Smith RG, Mosier DR, Atassi MZ. Subtle differences in HLA DQ haplotype-associated presentation of AChR α-chain peptides may suffice to mediate myasthenia gravis. Autoimmunity 2009; 39:277-88. [PMID: 16891216 DOI: 10.1080/08916930600738581] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The HLA DQA1 and DQB1 alleles were determined on a set of 24 myasthenia gravis patients that had previously been examined for their T-cell proliferative responses to the 18 overlapping peptides representing the extracellular domain of hAChR alpha-chain. Patient responses according to assumed cis or trans haplotypes were significantly higher in most cases relative to normal controls. Comparisons of in vitro peptide-stimulated T-cell responses of patient pairs which had DQA1:DQB1 in common displayed responses in tighter distribution relative to comparisons in which patient pairs did not share the same DQA1:DQB1 haplotype. Similar haplotypes, such as DQA1*0102:DQB1*0602 and DQA1*0102:DQB1*0604, tended to exhibit similar responses and were grouped according to this similarity. Modified F-test and Student's T-test analyses on DQ isoform bearing groups revealed that high responses to peptide alpha34-49 were associated with A1*0102:B1*0602/0604, A1*0301:B1*0302 and A1*0401/0303:B1*0301. Peptide alpha146-162 showed higher responses in A1*0301:B1*0302 group and moderate responses in A1*0401/0303:B1*0301 groups. Differences in the age of disease onset relative to DQ haplotypes were also observed. Groups of A1*0301:B1*0302, A1*0501:B1*0201 and A1*0102:B1*0604 showed earlier ages of disease onset relative to those of A1*0102:B1*0602 or A1*0505:B1*0301.
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Affiliation(s)
- Philip R Deitiker
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
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7
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Oshima M, Maruta T, Ohtani M, Deitiker PR, Mosier D, Atassi MZ. Vaccination with a MHC class II peptide in Alum and inactive pertussis strongly ameliorates clinical MG in C57BL/6 mice. J Neuroimmunol 2006; 171:8-16. [PMID: 16271400 DOI: 10.1016/j.jneuroim.2005.09.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2005] [Revised: 08/15/2005] [Accepted: 09/09/2005] [Indexed: 10/25/2022]
Abstract
We have investigated the efficacy of immunization against peptides from predisposing MHC class II molecules in human-compatible adjuvants for ameliorating experimental autoimmune myasthenia gravis (EAMG). C57BL/6 mice were immunized three times with the peptide I-Abetab62-76 in Alum+killed pertussis organisms (PT) prior to two injections with tAChR. The treatment greatly reduced the occurrence and severity of clinical MG relative to controls that received saline/Alum+PT or none. It also reduced antibody and T-cell responses against tAChR. The results have important implications for the possible immunotherapy of MG by targeting disease-associated MHC.
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MESH Headings
- Action Potentials/physiology
- Alum Compounds
- Animals
- Antibodies/therapeutic use
- Antibody Formation
- Cell Proliferation/drug effects
- Disease Models, Animal
- Female
- Histocompatibility Antigens Class II/administration & dosage
- Histocompatibility Antigens Class II/immunology
- Humans
- Lymph Nodes/cytology
- Lymphocyte Activation
- Mice
- Mice, Inbred C57BL
- Muscle, Skeletal/physiopathology
- Myasthenia Gravis, Autoimmune, Experimental/immunology
- Myasthenia Gravis, Autoimmune, Experimental/physiopathology
- Myasthenia Gravis, Autoimmune, Experimental/prevention & control
- Pertussis Vaccine/administration & dosage
- Pertussis Vaccine/immunology
- Physical Conditioning, Animal/methods
- Radioimmunoassay/methods
- Receptors, Cholinergic/immunology
- Torpedo
- Vaccination/methods
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Affiliation(s)
- Minako Oshima
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
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Stacy S, Gelb BE, Koop BA, Windle JJ, Wall KA, Krolick KA, Infante AJ, Kraig E. Split tolerance in a novel transgenic model of autoimmune myasthenia gravis. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 169:6570-9. [PMID: 12444169 DOI: 10.4049/jimmunol.169.11.6570] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Because it is one of the few autoimmune disorders in which the target autoantigen has been definitively identified, myasthenia gravis (MG) provides a unique opportunity for testing basic concepts of immune tolerance. In most MG patients, Abs against the acetylcholine receptors (AChR) at the neuromuscular junction can be readily identified and have been directly shown to cause muscle weakness. T cells have also been implicated and appear to play a role in regulating the pathogenic B cells. A murine MG model, generated by immunizing mice with heterologous AChR from the electric fish Torpedo californica, has been used extensively. In these animals, Abs cross-react with murine AChR; however, the T cells do not. Thus, to study tolerance to AChR, a transgenic mouse model was generated in which the immunodominant Torpedo AChR (T-AChR) alpha subunit is expressed in appropriate tissues. Upon immunization, these mice showed greatly reduced T cell responses to T-AChR and the immunodominant alpha-chain peptide. Limiting dilution assays suggest the likely mechanism of tolerance is deletion or anergy. Despite this tolerance, immunization with intact T-AChR induced anti-AChR Abs, including Abs against the alpha subunit, and the incidence of MG-like symptoms was similar to that of wild-type animals. Furthermore, evidence suggests that this B cell response to the alpha-chain receives help from T cells directed against the other AChR polypeptides (beta, gamma, or delta). This model offers a novel opportunity to elucidate mechanisms of tolerance regulation to muscle AChR and to clarify the role of T cells in MG.
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Affiliation(s)
- Sue Stacy
- Department of Cellular and Structural Biology, University of Texas Health Science Center, San Antonio 78229, USA
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9
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Abstract
This review will address a paradox that has long fascinated scientists studying the effects of aging on the immune system. Although it has been clearly documented that B and T lymphocytes lose the ability to respond to antigenic or mitogenic stimulation with age, it has nonetheless been noted that the frequency of autoreactive antibodies is higher in older individuals. Given that the majority of the age-associated defects in immune regulation target the naïve T and B lymphocyte subsets, it has been presumed that this increase in antibodies specific for self antigens was due to changes in the B cell repertoire and/or to differences in the mechanisms responsible for generating immune tolerance in primary responses. However, in this review, we will address an alternative possibility that memory immune responses, first generated when the individual was young, may play a critical role in the appearance of serum autoantibodies by reactivation later in life (recall memory). It has recently been shown, in several different systems, that memory immunity can be maintained over the lifetime of the animal. Thus, memory B cells which are self-reactive may be harbored within an organism as it ages and the potential exists that they become re-activated at a later time, resulting in a vigorous autoreactive recall response. This may occur preferentially in older individuals due to several factors, including deficiencies in immune tolerance with age, progressive age-associated loss of tissue integrity yielding neo-self antigens, and possible re-exposure to an infectious agent which induces an autoimmune memory response through molecular mimicry. Thus, we propose that some of the autoantibodies seen in elderly patients and in older animals may have been produced by memory lymphocytes originally generated against antigens encountered during one's youth, but maintained in a tolerant (non reactive) state until a subsequent triggering event occurs. Possible implications of this model will be discussed.
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Affiliation(s)
- Sue Stacy
- Department of Cellular and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229-3900, USA
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10
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Wang HB, Shi FD, Li H, Chambers BJ, Link H, Ljunggren HG. Anti-CTLA-4 antibody treatment triggers determinant spreading and enhances murine myasthenia gravis. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 166:6430-6. [PMID: 11342669 DOI: 10.4049/jimmunol.166.10.6430] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CTLA-4 appears to be a negative regulator of T cell activation and is implicated in T cell-mediated autoimmune diseases. Experimental autoimmune myasthenia gravis (EAMG), induced by immunization of C57BL/6 mice with acetylcholine receptor (AChR) in adjuvant, is an autoantibody-mediated disease model for human myasthenia gravis (MG). The production of anti-AChR Abs in MG and EAMG is T cell dependent. In the present study, we demonstrate that anti-CTLA-4 Ab treatment enhances T cell responses to AChR, increases anti-AChR Ab production, and provokes a rapid onset and severe EAMG. To address possible mechanisms underlying the enhanced autoreactive T cell responses after anti-CTLA-4 Ab treatment, mice were immunized with the immunodominant peptide alpha(146-162) representing an extracellular sequence of the ACHR: Anti-CTLA-4 Ab, but not control Ab, treatment subsequent to peptide immunization results in clinical EAMG with diversification of the autoantibody repertoire as well as enhanced T cell proliferation against not only the immunizing alpha(146-162) peptide, but also against other subdominant epitopes. Thus, treatment with anti-CTLA-4 Ab appears to induce determinant spreading, diversify the autoantibody repertoire, and enhance B cell-mediated autoimmune disease in this murine model of MG.
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MESH Headings
- Abatacept
- Adjuvants, Immunologic/administration & dosage
- Amino Acid Sequence
- Animals
- Antibodies/administration & dosage
- Antibody Diversity
- Antigens, CD
- Antigens, Differentiation/immunology
- Autoantibodies/biosynthesis
- CTLA-4 Antigen
- Disease Models, Animal
- Disease Progression
- Epitopes, T-Lymphocyte/metabolism
- Female
- Immunization
- Immunoconjugates
- Immunodominant Epitopes/metabolism
- Immunoglobulin G/biosynthesis
- Injections, Subcutaneous
- Mice
- Mice, Inbred C57BL
- Molecular Sequence Data
- Myasthenia Gravis/etiology
- Myasthenia Gravis/immunology
- Peptide Fragments/administration & dosage
- Peptide Fragments/immunology
- Receptors, Cholinergic/administration & dosage
- Receptors, Cholinergic/immunology
- Receptors, Cholinergic/metabolism
- T-Lymphocytes/immunology
- T-Lymphocytes/metabolism
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Affiliation(s)
- H B Wang
- Experimental Neurology Unit, Division of Neurology, and Department of Medicine, Center for Infectious Medicine, Karolinska Institute, Huddinge University Hospital, Stockholm, Sweden
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11
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Ostlie NS, Karachunski PI, Wang W, Monfardini C, Kronenberg M, Conti-Fine BM. Transgenic expression of IL-10 in T cells facilitates development of experimental myasthenia gravis. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 166:4853-62. [PMID: 11290761 DOI: 10.4049/jimmunol.166.8.4853] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Ab to the acetylcholine receptor (AChR) cause experimental myasthenia gravis (EMG). Th1 cytokines facilitate EMG, whereas Th2 cytokines might be protective. IL-10 inhibits Th1 responses but facilitates B cell proliferation and Ig production. We examined the role of IL-10 in EMG by using wild-type (WT) C57BL/6 mice and transgenic (TG) C57BL/6 mice that express IL-10 under control of the IL-2 promoter. We immunized the mice with doses of AChR that cause EMG in WT mice or with low doses ineffective at causing EMG in WT mice. After low-dose AChR immunization, WT mice did not develop EMG and had very little anti-AChR serum Ab, which were mainly IgG1, whereas TG mice developed EMG and had higher levels of anti-AChR serum Ab, which were mainly IgG2, in addition to IgG1. At the higher doses, TG mice developed EMG earlier and more frequently than WT mice and had more serum anti-AChR Ab. Both strains had similar relative serum concentrations of anti-AChR IgG subclasses and IgG and complement at the muscle synapses. CD8(+)-depleted splenocytes from all AChR-immunized mice proliferated in the presence of AChR and recognized a similar epitope repertoire. CD8(+)-depleted splenocytes from AChR-immunized TG mice stimulated in vitro with AChR secreted significantly more IL-10, but less of the prototypic Th1 cytokine IFN-gamma, than those from WT mice. They secreted comparable amounts of IL-4 and slightly but not significantly reduced amounts of IL-2. This suggests that TG mice had reduced activation of anti-Torpedo AChR Th1 cells, but increased anti-AChR Ab synthesis, that likely resulted from IL-10-mediated stimulation of anti-AChR B cells. Thus, EMG development is not strictly dependent on Th1 cell activity.
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Affiliation(s)
- N S Ostlie
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, St. Paul, MN 55108, USA
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12
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Oshima M, Atassi MZ. T cells of mice treated with mPEG-myasthenogenic peptide conjugate are involved in protection against EAMG by stimulating lower pathogenic antibody responses. Autoimmunity 2001; 32:45-55. [PMID: 10958175 DOI: 10.3109/08916930008995987] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Experimental autoimmune myasthenia gravis (EAMG) can be induced in C57BL/6 (B6) mice by immunization with Torpedo californica acetylcholine receptor (tAChR). We had previously shown that pretreatment with a monomethoxypolyethylene glycol (mPEG) conjugate of myasthenogenic tAChR alpha-chain peptide alpha125-148 (mPEG-peptide) suppressed EAMG. In order to understand the mechanism involving T cells in the induction of this suppression, we have studied, in the present work, the in vitro responses of T cells from mPEG-peptide treated B6 mice after an initial tAChR injection to determine the early effect of mPEG-peptide treatment on these responses. Treatment with mPEG-peptide reduced the T cell responses to tAChR and several tAChR alpha-chain peptides. To further investigate the T cell helper function in vivo, we transferred T cells from B6 mice that received either mPEG-peptide or control PBS followed by two tAChR injections to non-immune B6 mice. T cell transfer from mPEG-peptide pretreated mice down regulated, in recipient mice, Ab induction (after cell transfer) and Ab production (after two tAChR injections) toward alpha-chain peptides. Treatment of B6 mice with mPEG-peptide did not alter the ability of their APC to present peptide alpha146-162 to peptide-specific B6 T cells. The results indicate that suppression of EAMG by treatment with mPEG-peptide is due to T cell involvement and not to a defect in APC function.
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Affiliation(s)
- M Oshima
- Department of Biochemistry, Baylor College of Medicine, Houston, TX 77030, USA
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13
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Nakayashiki N, Oshima M, Deitiker PR, Ashizawa T, Atassi MZ. Suppression of experimental myasthenia gravis by monoclonal antibodies against MHC peptide region involved in presentation of a pathogenic T-cell epitope. J Neuroimmunol 2000; 105:131-44. [PMID: 10742555 DOI: 10.1016/s0165-5728(00)00199-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have prepared monoclonal antibodies (mAbs) against an antigen-binding region of I-A, region 62-76 of I-Abeta(b), which is involved in the T-cell participation in the pathogenesis of EAMG. The mAbs reacted with its parent molecules and inhibited the proliferation of disease-related T-cells. Passive transfer of these mAbs suppressed the occurrence of clinical EAMG, which was accompanied by decreased T-cell and Ab responses to tAChR. The results indicated that blocking the function of disease-related MHC by targeting a disease-associated region on MHC molecules could be an effective, straightforward and feasible strategy for immunointervention in MG.
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Affiliation(s)
- N Nakayashiki
- Department of Biochemistry, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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14
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Abstract
Much progress has been made in the 26 years since initial studies of the first purified acetylcholine receptors (AChRs) led to the discovery that an antibody-mediated autoimmune response to AChRs causes the muscular weakness and fatigability characteristic of myasthenia gravis (MG) and its animal model, experimental autoimmune myasthenia gravis (EAMG). Now, the structure of muscle AChRs is much better known. Monoclonal antibodies to muscle AChRs, developed as model autoantibodies for studies of EAMG, were used for initial purifications of neuronal AChRs, and now many homologous subunits of neuronal nicotinic AChRs have been cloned. There is a basic understanding of the pathological mechanisms by which autoantibodies to AChRs impair neuromuscular transmission. Immunodiagnostic assays for MG are used routinely. Nonspecific approaches to immunosuppressive therapy have been refined. However, fundamental mysteries remain regarding what initiates and sustains the autoimmune response to muscle AChRs and how to specifically suppress this autoimmune response using a practical therapy. Many rare congenital myasthenic syndromes have been elegantly shown to result from mutations in muscle AChRs. These studies have provided insights into AChR structure and function as well as into the pathological mechanisms of these diseases. Evidence has been found for autoimmune responses even to some central nervous system neurotransmitter receptors, but only one neuronal AChR has so far been implicated in an autoimmune disease. Thus far, only two neuronal AChR mutations have been found to be associated with a rare form of epilepsy, but many more neuronal AChR mutations will probably be found to be associated with disease in the years ahead.
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Affiliation(s)
- J M Lindstrom
- Department of Neuroscience, Medical School of the University of Pennsylvania, Philadelphia, Pennsylvania 19104-6074, USA.
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15
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Deitiker P, Ashizawa T, Atassi MZ. Antigen mimicry in autoimmune disease. Can immune responses to microbial antigens that mimic acetylcholine receptor act as initial triggers of Myasthenia gravis? Hum Immunol 2000; 61:255-65. [PMID: 10689115 DOI: 10.1016/s0198-8859(99)00117-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Myasthenia gravis (MG) is an autoimmune disease caused by autoantibodies against self acetylcholine receptor (AChR). Although a great deal of information is known about the molecular and cellular parameters of the disease, its initial trigger is not known. In order to study the possibility of the involvement of microbial antigens that mimic AChR in triggering MG, we have searched the microbial proteins in the data bank for regions that are similar in structure to the regions of human (h) AChR alpha chain recognized by autoAbs in MG patients. Hundreds of candidate structures on a large number of bacterial and viral proteins were identified. To test the feasibility of the idea, we synthesized four microbial regions similar to each of the major autodeterminants of hAChR (alpha12-27, alpha111-126, alpha122-138, alpha182-200) and investigated their ability to bind autoAbs in MG and normal sera controls. It was found that MG sera recognized a significant number of these microbial regions. The results indicate that in some MG cases immune responses to microbial antigens may cross-react with self antigen (in this case hAChR) and could constitute initial triggers of the disease.
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Affiliation(s)
- P Deitiker
- Department of Biochemistry, Baylor College of Medicine, Houston, Texas, USA
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16
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Vincent A, Willcox N, Hill M, Curnow J, MacLennan C, Beeson D. Determinant spreading and immune responses to acetylcholine receptors in myasthenia gravis. Immunol Rev 1998; 164:157-68. [PMID: 9795773 DOI: 10.1111/j.1600-065x.1998.tb01217.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In myasthenia gravis (MG), antibodies to the muscle acetylcholine receptor (AChR) cause muscle weakness. Experimental autoimmune myasthenia gravis (EAMG) can be induced by immunisation against purified AChR; the main immunogenic region (MIR) is a conformation-dependent site that includes alpha 67-76. EAMG can also occur after immunisation against extracellular AChR sequences, but this probably involves intramolecular determinant spreading. In MG patients, thymic hyperplasia and germinal centres are found in about 50%, and thymoma in 10-15%. The heterogeneous, high affinity, IgG anti-AChR antibodies appear to be end-products of germinal centre responses, and react mainly with the MIR or a site on fetal AChR; the latter contains a gamma subunit and is mainly expressed on myoid cells in the thymic medulla. T cells cloned against recombinant AChR subunits recognise principally two naturally processed epitopes: epsilon 201-219 derived from adult AChR which is expressed in muscle, and sometimes in thymic epithelium, and alpha 146-160, common to fetal and adult AChR. Since AChR is not normally co-expressed with class II, it is unclear how CD4+ responses to AChR alpha and epsilon subunits are initiated, and how and where these spread to induce antibodies against fetal AChR. Various possibilities, including upregulation of class II on muscle/myoid cells and involvement of CD8+ responses to AChR and other muscle antigens, are discussed.
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Affiliation(s)
- A Vincent
- Department of Clinical Neurology, John Radcliffe Hospital, Oxford, UK.
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Oshima M, Yokoi T, Deitiker P, Atassi MZ. T cell responses in EAMG-susceptible and non-susceptible mouse strains after immunization with overlapping peptides encompassing the extracellular part of Torpedo californica acetylcholine receptor alpha chain. Implication to role in myasthenia gravis of autoimmune T-cell responses against receptor degradation products. Autoimmunity 1998; 27:79-90. [PMID: 9583739 DOI: 10.3109/08916939809008038] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
To study the role in myasthenia gravis (MG) of peptides resulting from acetylcholine receptor (AChR) degradation, we examined the ability of AChR peptides to induce T cell responses that are capable of cross-reacting with intact AChR. The studies were carried out in an experimental autoimmune MG (EAMG)-susceptible mouse strain [C57BL/6 (B6)] as well as in two non-susceptible strains [B6.C-H-2bm12 (bm12) and C3H/He]. A set of overlapping peptides encompassing the extracellular part (residues 1-210) of the alpha-chain of Torpedo californica (t) AChR were used, individually or in equimolar mixtures, as immunogens. In B6, immunization with peptides alpha45-60, alpha111-126, alpha146-162 and alpha182-198 gave T cells that responded in vitro to the correlate immunizing peptide. Only the T cells against the latter three peptides cross-reacted with tAChR. Peptide alpha146-162 exhibited the highest in vitro reaction with the immunizing peptide and cross-reaction with tAChR. T cells obtained by immunization of B6 with an equimolar mixture of the peptides responded in vitro to peptides alpha111-126, alpha146-162 and alpha182-198 and cross-reacted very strongly with tAChR. In bm12 and C3H/He, a number of peptides evoked, when used individually as immunogens, strong or moderate T cell responses that recognized in vitro the correlate immunizing peptide but cross-reacted poorly with tAChR. Immunization with the mixture of the peptides gave T cells that recognized several peptides in each strain butdid not cross-react with alpha146-162 or tAChR. The results indicate that the ability to recognize alpha146-162 or AChR by T cells against peptides resulting from receptor degradation can account for the susceptibility to, and aggravation of, MG in B6.
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Affiliation(s)
- M Oshima
- Verna and Marrs McLean Department of Biochemistry, Baylor College of Medicine, Houston, TX 77030, USA
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Oshima M, Hayakari M, Middlebrook JL, Atassi MZ. Immune recognition of botulinum neurotoxin type A: regions recognized by T cells and antibodies against the protective H(C) fragment (residues 855-1296) of the toxin. Mol Immunol 1997; 34:1031-40. [PMID: 9488054 DOI: 10.1016/s0161-5890(97)00107-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Botulism toxicity is caused by botulinum neurotoxins (BoNTs), a group of protein neurotoxins produced by Clostridium botulinum. Recent studies have shown that immunization with a C-terminal fragment [H(C), residues 855-1296] of BoNT type A (BoNT/A) affords excellent protection against BoNT/A toxicity. The present work was carried out in order to map the molecular and cellular immunological recognition of H(C). We have previously described the synthesis of 31 overlapping peptides encompassing the entire H(C)-fragment of BoNT/A. These peptides were employed in this study to localize the continuous regions recognized by T cells and by antibodies (Abs) generated in two mouse strains against H(C). T cells from SJL that had been primed with H(C) gave a strong proliferative response to challenge in vitro with each of the six peptides spanning residues 897-985 and a lower response to peptide 1051- 1069. While H(C)-primed T cells of BALB/c recognized three regions residing within residues 939-957, 1009-1027 and 1135-1153 (strong). Recognition regions by Abs in SJL or BALB/c anti-H(C) antisera essentially overlapped. However, the level of Abs bound to each region differed between the two strains. These common or similar recognition regions by the two strains were: 855-915 (SJL) or 855-901 (BALB/c); 939-957; 967-1013 (BALB/c) or 981-1013 (SJL); 1051-1069; 1079-1111 (BALB/c) or 1093-1125 (SJL); 1177-1195; and 1275-1296. In addition, BALB/c recognized region 1135-1153. Some of these regions show considerable sequence similarity in BoNT types B and E and, therefore, H(C) of these two BoNTs might offer protection against the correlate clostridial toxins.
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Affiliation(s)
- M Oshima
- Department of Biochemistry, Baylor College of Medicine, Houston, TX 77030, USA
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Atassi MZ, Oshima M. Autoimmune recognition of acetylcholine receptor and manipulation of the autoimmune responses by synthetic peptides. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1995; 383:141-56. [PMID: 8644499 DOI: 10.1007/978-1-4615-1891-4_17] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- M Z Atassi
- Department of Biochemistry, Baylor College of Medicine, Houston, Texas 77030, USA
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Jinnai K, Ashizawa T, Atassi MZ. Analysis of exposed regions on the main extracellular domain of mouse acetylcholine receptor alpha subunit in live muscle cells by binding profiles of antipeptide antibodies. JOURNAL OF PROTEIN CHEMISTRY 1994; 13:715-22. [PMID: 7710661 DOI: 10.1007/bf01886954] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
To study the structural organization of the main extracellular domain of the nicotinic acetylcholine receptor (AChR) alpha subunit in live muscle cells, we examined the native membrane-bound receptors in cultured mouse skeletal muscle cells for their ability to bind a panel of antibodies against uniform-sized overlapping synthetic peptides which collectively represent this entire domain. The binding profile indicated that the regions alpha 23-49, alpha 78-126, alpha 146-174, and alpha 182-210 are accessible to binding with antibody. Residues alpha 23-49, alpha 78-126, and alpha 194-210 contain binding regions for alpha-neurotoxin and some myasthenia gravis autoantibodies. A comparison of this binding profile with the profile obtained for membrane-bound Torpedo californica AChR in isolated membrane fractions showed some similarities as well as significant differences between the subunit organization in the isolated membrane fraction and that in the membrane of live muscle cells. Regions alpha 89-104 and alpha 158-174, which are exposed in the isolated membrane fraction, are also exposed in the live cell. On the other hand, regions alpha 23-49, and alpha 182-210, which are exposed in the live cell, are not accessible in the isolated membrane and, furthermore, the region alpha 1-16, which has marginal accessibility in the cell, becomes highly accessible in the membrane isolates. The exposed regions defined by this study may be the primary targets for the initial autoimmune attack on the receptors in experimental autoimmune myasthenia gravis.
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Affiliation(s)
- K Jinnai
- Department of Neurology, Baylor College of Medicine, Houston, Texas 77030, USA
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