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Ahlawat J, Sharma M, Shekhar Pundir C. Advances in biosensor development for detection of acetylcholine. Microchem J 2023. [DOI: 10.1016/j.microc.2023.108620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2023]
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A novel electroanalytical biosensor based on ZIF‐8/acetylcholinesterase bio‐nanohybrids for early management of Hirschsprung Disease. ELECTROANAL 2022. [DOI: 10.1002/elan.202200203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Plomp JJ, Huijbers MGM, Verschuuren JJGM, Borodovsky A. A bioassay for neuromuscular junction-restricted complement activation by myasthenia gravis acetylcholine receptor antibodies. J Neurosci Methods 2022; 373:109551. [PMID: 35247492 DOI: 10.1016/j.jneumeth.2022.109551] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 02/24/2022] [Accepted: 02/26/2022] [Indexed: 01/31/2023]
Abstract
BACKGROUND Myasthenia gravis (MG) is an autoimmune neuromuscular disorder hallmarked by fluctuating fatigable muscle weakness. Most patients have autoantibodies against acetylcholine receptors (AChRs) at the neuromuscular junction (NMJ). These are thought to have three possible pathogenic mode-of-actions: 1) cross-linking and endocytosis of AChRs, 2) direct block of AChRs and 3) complement activation. The relative contributions of these mechanisms to synaptic block and muscle weakness of individual patients cannot be determined. It likely varies between patients and perhaps also with disease course, depending on the nature of the circulating AChR antibodies. NEW METHOD We developed a new bioassay which specifically enables functional characterization and quantification of complement-mediated synaptic damage at NMJs, without interference of the other pathogenic mechanisms. To this end, we pre-incubated mouse hemi-diaphragm muscle-nerve preparations with mAb35-hG1, a humanized rat AChR monoclonal and subsequently exposed the preparation to normal human serum as a complement source. NMJ-restricted effects were studied. RESULTS Clearly NMJ-restricted damage occurred. With immunohistology we showed complement deposition at NMJs, and synaptic electrophysiological measurements demonstrated transmission block. In whole-muscle contraction experiments we quantified the effect and characterized its onset and progression during the incubation with normal human serum. COMPARISON WITH EXISTING METHODS With this new assay the complement-mediated component of myasthenic NMJ pathology can be studied separately. CONCLUSIONS Our assay will be of importance in detailed mechanistic studies of local complement activation at NMJs, investigations of new complement inhibitors, and laboratory pre-screening of therapeutic efficacy for individual MG patients to optimize care with clinically approved complement inhibitors.
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Affiliation(s)
| | - Maartje G M Huijbers
- Departments of Neurolog; Human Genetics, Leiden University Medical Centre, Leiden, The Netherlands
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Urriola N, Lang B, Adelstein S. Evaluation of commercially available antibodies and fluorescent conotoxins for the detection of surface ganglionic acetylcholine receptor on the neuroblastoma cell line, IMR-32 by flow cytometry. J Immunol Methods 2021; 498:113124. [PMID: 34425081 DOI: 10.1016/j.jim.2021.113124] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 08/16/2021] [Accepted: 08/17/2021] [Indexed: 11/28/2022]
Abstract
Commercially available antibodies that bind to the human muscle acetylcholine receptor (ACHR) have been validated previously for flow cytometric use (Keefe et al., 2009; Leite et al., 2008; Lozier et al., 2015). Despite a multitude of commercially available antibodies to other nicotinic ACHRs, validation in a wide variety of immunoassay formats is lacking; when studied, a large proportion of these antibodies have been deemed not fit for most research purposes (Garg and Loring, 2017). We have recently described a flow cytometric immunomodulation assay for the diagnosis of Autoimmune Autonomic Ganglionopathy (AAG) (Urriola et al., 2021) that utilises the monoclonal antibody mab35(Urriola et al., 2021) which is specific for ganglionic ACHR (gnACHR) that contain α3 subunits (Vernino et al., 1998). Other fluorescent ligands for α3-gnACHR have not been validated for flow cytometric use. We investigated 7 commercially sourced antibodies and 3 synthetic fluorescent novel conotoxins purported to specifically bind to the extracellular domains of the gnACHR, and compared the results to staining by mab35, using flow cytometry with the neuroblastoma cell line IMR-32. We also evaluated the degree of non-specific binding by depleting the cell membrane of the relevant acetylcholine receptor with a pre-incubation step involving the serum from a patient with Autoimmune Autonomic Ganglionopathy containing pathogenic antibodies to the ganglionic acetylcholine receptor. None of the assessed conotoxins, and only one antibody (mab35) was found to perform adequately in flow cytometric staining of the native ganglionic acetylcholine receptor.
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Affiliation(s)
- Nicolás Urriola
- Department of Clinical Immunology and Allergy, Royal Prince Alfred Hospital, Sydney, Australia; Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia.
| | - Bethan Lang
- Nuffield Department of Clinical Neurosciences, University of Oxford, UK
| | - Stephen Adelstein
- Department of Clinical Immunology and Allergy, Royal Prince Alfred Hospital, Sydney, Australia; Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia; Central Sydney Immunopathology Laboratory, NSW Health Pathology, Australia
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Cai Y, Han L, Zhu D, Peng J, Li J, Ding J, Luo J, Hong R, Wang K, Wan W, Xie C, Zhou X, Zhang Y, Hao Y, Guan Y. A Stable Cell Line Expressing Clustered AChR: A Novel Cell-Based Assay for Anti-AChR Antibody Detection in Myasthenia Gravis. Front Immunol 2021; 12:666046. [PMID: 34305897 PMCID: PMC8297518 DOI: 10.3389/fimmu.2021.666046] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 05/28/2021] [Indexed: 12/13/2022] Open
Abstract
Cell-based assays (CBAs) and radioimmunoprecipitation assay (RIPA) are the most sensitive methods for identifying anti-acetylcholine receptor (AChR) antibody in myasthenia gravis (MG). But CBAs are limited in clinical practice by transient transfection. We established a stable cell line (KL525) expressing clustered AChR by infecting HEK 293T cells with dual lentiviral vectors expressing the genes encoding the human AChR α1, β1, δ, ϵ and the clustering protein rapsyn. We verified the stable expression of human clustered AChR by immunofluorescence, immunoblotting, and real-time PCR. Fluorescence-activated cell sorting (FACS) was used to detect anti-AChR antibodies in 103 MG patients and 58 healthy individuals. The positive results of MG patients reported by the KL525 was 80.6% (83/103), 29.1% higher than the 51.4% (53/103) of RIPA. 58 healthy individuals tested by both the KL525 CBA and RIPA were all negative. In summary, the stable expression of clustered AChR in our cell line makes it highly sensitive and advantageous for broad clinical application in CBAs.
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Affiliation(s)
- Yu Cai
- Department of Neurology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Lu Han
- Department of Neurology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Desheng Zhu
- Department of Neurology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Jing Peng
- Department of Neurology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Jianping Li
- Department of Neurology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Jie Ding
- Department of Neurology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Jiaying Luo
- Department of Neurology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Ronghua Hong
- Department of Neurology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Kan Wang
- Department of Neurology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Wenbin Wan
- Department of Neurology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Chong Xie
- Department of Neurology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Xiajun Zhou
- Department of Neurology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Ying Zhang
- Department of Neurology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Yong Hao
- Department of Neurology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Yangtai Guan
- Department of Neurology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
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Frykman H, Kumar P, Oger J. Immunopathology of Autoimmune Myasthenia Gravis: Implications for Improved Testing Algorithms and Treatment Strategies. Front Neurol 2020; 11:596621. [PMID: 33362698 PMCID: PMC7755715 DOI: 10.3389/fneur.2020.596621] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 11/19/2020] [Indexed: 12/13/2022] Open
Abstract
Myasthenia gravis (MG) is a heterogeneous condition, characterized by autoantibodies (Abs) that target functionally important structures within neuromuscular junctions (NMJ), thus affecting nerve-to-muscle transmission. MG patients are more often now subgrouped based on the profile of serum autoantibodies, which segregate with clinical presentation, immunopathology, and their response to therapies. The serological testing plays an essential role in confirming MG diagnosis and guiding disease management, although a small percentage of MG patients remain negative for antibodies. With the advancements in new highly effective pathophysiologically-specific immunotherapeutic options, it has become increasingly important to identify the specific Abs responsible for the pathogenicity in individual MG patients. There are several new assays and protocols being developed for the improved detection of Abs in MG patients. This review focuses on the divergent immunopathological mechanisms in MG, and discusses their relevance to improved diagnostic and treatment. We propose a comprehensive "reflex testing," algorithm for the presence of MG autoantibodies, and foresee that in the near future, the convenience and specificity of novel assays will permit the clinicians to consider them into routine systematic testing, thus stimulating laboratories to make these tests available. Moreover, adopting treatment driven testing algorithms will be crucial to identify subgroups of patients potentially benefiting from novel immunotherapies for MG.
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Affiliation(s)
- Hans Frykman
- Department of Medicine, University of British Columbia, Vancouver, BC, Canada.,BC Neuroimmunology Lab, University of British Columbia, Vancouver, BC, Canada
| | - Pankaj Kumar
- BC Neuroimmunology Lab, University of British Columbia, Vancouver, BC, Canada
| | - Joel Oger
- Department of Medicine, University of British Columbia, Vancouver, BC, Canada.,BC Neuroimmunology Lab, University of British Columbia, Vancouver, BC, Canada
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Hong Y, Liang X, Gilhus NE. AChR antibodies show a complex interaction with human skeletal muscle cells in a transcriptomic study. Sci Rep 2020; 10:11230. [PMID: 32641696 PMCID: PMC7343820 DOI: 10.1038/s41598-020-68185-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2019] [Accepted: 06/17/2020] [Indexed: 01/26/2023] Open
Abstract
Acetylcholine receptor (AChR) antibodies are the most important pathogenic marker in patients with myasthenia gravis (MG). The antibodies bind to AChRs on the postsynaptic membrane, and this leads to receptor degradation, destruction, or functional blocking with impaired signal at the neuromuscular junction. In this study, we have explored the effects of AChR antibodies binding to mature human myotubes with agrin-induced AChR clusters and pathways relevant for AChR degradation using bulk RNA sequencing. Protein-coding RNAs and lncRNAs were examined by RNA sequencing analysis. AChR antibodies induced marked changes of the transcriptomic profiles, with over 400 genes differentially expressed. Cholesterol metabolic processes and extracellular matrix organization gene sets were influenced and represent AChR-trafficking related pathways. Muscle contraction and cellular homeostasis gene sets were also affected, and independently of AChR trafficking. Furthermore, we found changes in a protein-coding RNA and lncRNA network, where expression of lncRNA MEG3 correlated closely with protein-coding genes for cellular homeostasis. We conclude that AChR antibodies induce an active response in human skeletal muscle cells which affects key intra- and extracellular pathways.
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Affiliation(s)
- Yu Hong
- Department of Clinical Medicine, University of Bergen, Bergen, Norway.
| | - Xiao Liang
- Department of Neurology, Haukeland University Hospital, Bergen, Norway
| | - Nils Erik Gilhus
- Department of Clinical Medicine, University of Bergen, Bergen, Norway.,Department of Neurology, Haukeland University Hospital, Bergen, Norway
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Heterogeneity of auto-antibodies against nAChR in myasthenic serum and their pathogenic roles in experimental autoimmune myasthenia gravis. J Neuroimmunol 2018; 320:64-75. [PMID: 29759142 DOI: 10.1016/j.jneuroim.2018.04.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 04/23/2018] [Accepted: 04/23/2018] [Indexed: 11/20/2022]
Abstract
Many myasthenia gravis (MG) patients have auto-antibodies against the nicotinic acetylcholine receptor (nAChR), and monoclonal antibodies against the main immunogenic region (MIR) of nAChR can induce experimental autoimmune MG (EAMG). We investigated whether Fab fragment of MIR antibody (Fab35) could block the pathogenicity of polyclonal antibodies. Fab35 partially inhibited nAChR downmodulation, blocked EAMG serum-induced binding of polyclonal antibodies and complement deposition in vitro. Moreover, Fab35 did not ameliorate the EAMG serum-induced EAMG phenotype in rats. These results suggested that the EAMG serum possessed several different pathogenic antibodies that might be sufficient to induce the EAMG phenotype.
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Cromar A, Lozier BK, Haven TR, Hill HR. Detection of Acetylcholine Receptor Blocking Antibodies by Flow Cytometry. Am J Clin Pathol 2016; 145:81-5. [PMID: 26712874 DOI: 10.1093/ajcp/aqv009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
OBJECTIVES Detection of acetylcholine receptor (AChR) blocking antibodies through the use of a radiolabel has become standard procedure in most laboratories. Known drawbacks associated with radioassay, including cost of radioisotopes, hazards to laboratory professionals, and manufacture and disposal of radioactive materials, have prompted investigation into replacement assays. We describe here a high-throughput immunofluorescent flow cytometric assay designed for the detection of AChR blocking antibodies. METHODS In total, 323 serum samples were tested on both the AChR blocking radioassay and the new immunofluorescent flow cytometric assay. RESULTS Analysis of the results revealed a 96.9% concordance between the two assay methods. CONCLUSIONS Our results indicate that a new immunofluorescent flow cytometric AChR blocking antibody assay is not only feasible but clinically comparable in both sensitivity (91%) and specificity (99%) compared with radioassay.
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Affiliation(s)
| | | | - Thomas R Haven
- From the ARUP Institute for Clinical and Experimental Pathology, Salt Lake City, UT Departments of Pathology
| | - Harry R Hill
- From the ARUP Institute for Clinical and Experimental Pathology, Salt Lake City, UT
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Chauhan N, Narang J, Jain U. Highly sensitive and rapid detection of acetylcholine using an ITO plate modified with platinum-graphene nanoparticles. Analyst 2015; 140:1988-94. [PMID: 25674632 DOI: 10.1039/c4an01873g] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Determining the concentrations of acetylcholine (ACh) and choline (Ch) is clinically important. ACh is a neurotransmitter that acts as a key link in the communication between neurons in the spinal cord and in nerve skeletal junctions in vertebrates, and plays an important role in transmitting signals in the brain. A bienzymatic sensor for the detection of ACh was prepared by co-immobilizing choline oxidase (ChO) and acetylcholinesterase (AChE) on graphene matrix/platinum nanoparticles, and then electrodepositing them on an ITO-coated glass plate. Graphene nanoparticles were decorated with platinum nanoparticles and were electrodeposited on a modified ITO-coated glass plate to form a modified electrode. The modified electrode was characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) studies. The optimum response of the enzyme electrode was obtained at pH 7.0 and 35 °C. The response time of this ACh-sensing system was shown to be 4 s. The linear range of responses to ACh was 0.005-700 μM. This biosensor exhibits excellent anti-interferential abilities and good stability, retaining 50% of its original current even after 4 months. It has been applied for the detection of ACh levels in human serum samples.
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Affiliation(s)
- Nidhi Chauhan
- Amity Institute of Nanotechnology, Amity University, Noida-201303, Uttar Pradesh, India
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Jin M, Hwang SM, Davies AJ, Shin Y, Bae JS, Lee JH, Lee EB, Song YW, Park K. Autoantibodies in primary Sjögren's syndrome patients induce internalization of muscarinic type 3 receptors. Biochim Biophys Acta Mol Basis Dis 2011; 1822:161-7. [PMID: 22137887 DOI: 10.1016/j.bbadis.2011.11.012] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Revised: 11/10/2011] [Accepted: 11/14/2011] [Indexed: 11/29/2022]
Abstract
OBJECTIVES Primary Sjögren's syndrome (pSS) is a systemic autoimmune disease characterized by lymphocyte infiltration into the salivary and lachrymal glands, leading to dry mouth and eyes. The presence of functional autoantibodies against muscarinic type 3 receptor (M3R) has been reported in pSS patients. However, the pathological role of anti-M3R autoantibodies in pSS salivary dysfunction remains controversial. METHODS Purified IgGs were obtained from normal (control) and primary SS patients' sera (pSS IgG). Internalization of M3R and clathrin was analyzed by biochemical assay and immunofluorescence confocal microscopy using human submandibular gland (hSMG) cells. Cytoplasmic free Ca(2+) concentration ([Ca(2+)](i)) was measured by microspectrofluorimetry. RESULTS Incubation of hSMG cells with pSS IgG (1mg/ml) significantly decreased M3R expression levels at the membrane. Carbachol-induced [Ca(2+)](i) transients (CICTs) in these cells were also inhibited by pSS IgG. In contrast to pSS IgG, control IgG had no effect on both the M3R expression level and CICTs. We found that binding of pSS IgG to M3R induces phosphorylation of the receptor, and that the pSS IgG-induced M3R internalization is prevented by the lysosomal inhibitor, chloroquine. In addition, pSS IgG decreased membrane clathrin expression, which was inhibited by atropine. Our immunofluorescence study further confirmed that pSS IgG induces a co-localization of M3R with clathrin and subsequent internalization of M3R. CONCLUSION pSS IgG induces internalization of M3R partly through a clathrin-mediated pathway. The results suggest M3R internalization as a potential mechanism to explain the exocrinopathy seen in pSS patients.
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Affiliation(s)
- Meihong Jin
- Department of Physiology, College of Medicine, Seoul National University and Dental Research Institute, Seoul 110-749, Republic of Korea
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Keefe D, Parng C, Lundberg D, Ray S, Martineau-Bosco J, Leng C, Tzartos S, Powell J, Concino M, Heartlein M, Lamsa J, Josiah S. In vitrocharacterization of an acetylcholine receptor–transferrin fusion protein for the treatment of myasthenia gravis. Autoimmunity 2010; 43:628-39. [DOI: 10.3109/08916931003599070] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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