Evaluating an In-House Cell-Based Assay for Detecting Antibodies Against Muscle-Specific Tyrosine Kinase in Myasthenia Gravis

Kim, Min Ju; Kim, Seung Woo; Kim, MinGi; Choi, Young Chul; Kim, Seung Min; Shin, Ha Young

doi:10.3988/jcn.2021.17.3.400

Cited by 8 publications

(6 citation statements)

References 29 publications

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“…The fluorescence intensity on the membranes of LRP4-transfected HEK293 cells and the overlapping of GFP-tagged LRP4 (green fluorescence) and AF594 label (red fluorescence) antibodies were evaluated using the following visual scoring system: 0 for no labeling of the transfected cells, 0.5 for very weak labeling of a few cells with no definite colocalization, 1 for weak labeling of some cells with colocalization, 2 for labeling of 20%–50% of cells with accurate colocalization, 3 for labeling of 50%–80% of cells with perfect colocalization, and 4 for labeling of all transfected cells with perfect colocalization. 5 13 14 A score of 1 or more was considered a positive result. The results were interpreted via the consensus of two independent investigators (M.J.K.…”

Section: Methodsmentioning

confidence: 99%

Development and Application of a Cell-Based Assay for LRP4 Antibody Associated With Myasthenia Gravis

Chung

Kim

et al. 2023

J Clin Neurol

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Background and Purpose Among patients with double-seronegative myasthenia gravis (dSN-MG) who do not have detectable antibodies against acetylcholine receptor or muscle-specific tyrosine kinase, autoantibodies against low-density lipoprotein receptor-related protein 4 (LRP4-Ab) have been detected recently. The purpose of this study was to develop an in-house cell-based assay (CBA) to detect LRP4-Ab and to apply it to samples from patients with MG. Methods The complementary DNA of LRP4 fused into a vector plasmid containing GFP was transfected into human embryonic kidney 293 (HEK293) cells. LRP4 expression in the transfected HEK293 cells was assessed using the reverse-transcription polymerase chain reaction (RT-PCR), Western blotting, and immunocytochemistry. The CBA included 252 sera collected from 202 patients with MG and 38 with other neuromuscular diseases, and 12 healthy controls. The transfected HEK293 cells were incubated using sera and antihuman immunoglobulin G antibodies conjugated with Alexa Fluor 594. The presence of LRP4-Ab was determined based on the fluorescence intensity and the localization in fluorescence microscopy. Results The expressions of the mRNA and protein of LRP4 in the transfected HEK293 cells were confirmed using RT-PCR and Western blotting, respectively. Immunocytochemistry indicated LPR4 expression on the cell membrane. Among 202 patients with MG including 53 with dSN-MG, LRP4-Ab were positive in 3 patients who were all double seronegative. LRP4-Ab were not detected in the patients with other neuromuscular diseases or the healthy controls. Conclusions A CBA for detecting LRP4-Ab associated with MG has been developed, and was used to find LRP4-Ab in the sera of patients with MG.

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Section: Methodsmentioning

confidence: 99%

Development and Application of a Cell-Based Assay for LRP4 Antibody Associated With Myasthenia Gravis

Chung

Kim

et al. 2023

J Clin Neurol

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“…RIA is positive for antibodies to muscle AChR in 80-85% of patients and for antibodies to MuSK in 5-7% of patients ( 38 ). To avoid radioactivity and increase sensitivity, cell-based assays (CBA) have been even more sensitive than RIA, as the antigen is expressed in a more native conformational form and more easily recognizable ( 133 , 134 ). An international study examining sera from 633 SNMG (seronegative MG) patients from 13 European countries, revealed a prevalence of 13% for MuSK antibodies (5–22% depending on the country) although most of the antibodies detected were predominantly of the IgM type ( 135 ).…”

Section: Diagnostic Tools For Musk Myasthenia Gravis (Electrophysiolo...mentioning

confidence: 99%

Immunotherapies in MuSK-positive Myasthenia Gravis; an IgG4 antibody-mediated disease

Vakrakou¹,

Karachaliou²,

Chroni³

et al. 2023

Front. Immunol.

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Muscle-specific kinase (MuSK) Myasthenia Gravis (MG) represents a prototypical antibody-mediated disease characterized by predominantly focal muscle weakness (neck, facial, and bulbar muscles) and fatigability. The pathogenic antibodies mostly belong to the immunoglobulin subclass (Ig)G4, a feature which attributes them their specific properties and pathogenic profile. On the other hand, acetylcholine receptor (AChR) MG, the most prevalent form of MG, is characterized by immunoglobulin (Ig)G1 and IgG3 antibodies to the AChR. IgG4 class autoantibodies are impotent to fix complement and only weakly bind Fc-receptors expressed on immune cells and exert their pathogenicity via interfering with the interaction between their targets and binding partners (e.g. between MuSK and LRP4). Cardinal differences between AChR and MuSK-MG are the thymus involvement (not prominent in MuSK-MG), the distinct HLA alleles, and core immunopathological patterns of pathology in neuromuscular junction, structure, and function. In MuSK-MG, classical treatment options are usually less effective (e.g. IVIG) with the need for prolonged and high doses of steroids difficult to be tapered to control symptoms. Exceptional clinical response to plasmapheresis and rituximab has been particularly observed in these patients. Reduction of antibody titers follows the clinical efficacy of anti-CD20 therapies, a feature implying the role of short-lived plasma cells (SLPB) in autoantibody production. Novel therapeutic monoclonal against B cells at different stages of their maturation (like plasmablasts), or against molecules involved in B cell activation, represent promising therapeutic targets. A revolution in autoantibody-mediated diseases is pharmacological interference with the neonatal Fc receptor, leading to a rapid reduction of circulating IgGs (including autoantibodies), an approach already suitable for AChR-MG and promising for MuSK-MG. New precision medicine approaches involve Chimeric autoantibody receptor T (CAAR-T) cells that are engineered to target antigen-specific B cells in MuSK-MG and represent a milestone in the development of targeted immunotherapies. This review aims to provide a detailed update on the pathomechanisms involved in MuSK-MG (cellular and humoral aberrations), fostering the understanding of the latest indications regarding the efficacy of different treatment strategies.

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“…Intravenous immunoglobulin, plasma exchange, as well as thymectomy, can be considered also as effective treatments for Myasthenia Gravis (Misra et al, 2020). Hence, engagement of patients with Myasthenia Gravis in health-promoting behaviors is a key factor in promoting physical, social and psychological wellbeing and preventing additional health problems as the majority of patients do not return to pre-morbid levels of functioning and find it difficult to maintain the daily activities (Kim et al, 2021). Health promoting behaviors were selected as dependent variables in the current study due to the direct impact on quality of life (Suppiah, Marshall, Lee & Looi, 2022).…”

Section: Introductionmentioning

confidence: 99%

Predictors to Health Promoting Behaviors among Patients with Myasthenia Gravis: Health Belief Model Approach

2023

JPTCP

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Myasthenia Gravis is a rare, chronic, acquired autoimmune neuromuscular disorder causing weakness in skeletal muscles. Patients with Myasthenia Gravis face many bio-psychosocial consequences that may require dramatic changes in their lives. The aim of this study was to determine predictors to health promoting behaviors among patients with Myasthenia Gravis using Health Belief Model. A predictive correlational research design was utilized to fulfill the aim of the study. Consecutive sample of convenience consisting of 57 adult male and female patients admitted for 21 months at one of Cairo University Hospitals, Egypt constituted the study sample. Data was collected using the following tools:(a) Demographic and Medical Background Data Form, (b) Glasgow Coma Scale to determine the conscious level of the potential participants, (c) The Adapted Health-Promoting Lifestyle Profile II tool to assess the health-promoting behaviors among the study participants and (d) the Health Belief Model Scale to assess the disease variables that were supposedly act as the predictors to health promoting behaviors among the study participants. Results showed that the majority of participants were female (78.90%), married (66.70%), educated (96.50%) and not working (91.20%), with a mean age of 33.96 ±9.81. Most of the participants have no family history of the disease (96.50%), have generalized Myasthenia Gravis (68.40%), their age at disease onset is between 20 to 40 years old (71.90%) and initial signs and symptoms are ptosis, limbs weakness and dysphagia (49.10 %, 40.40 % and 35.10% respectively). Additionally, more than one third of the study participants achieved low level of total health promoting behaviors. Accordingly, only two health belief model constructs, i.e., self-efficacy and cues to action shown to be predictors to health promoting behaviors. The study recommends that a self-management program should be designed to provide the patients with the necessary tools to improve self-efficacy and enhance management skills.

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Evaluating an In-House Cell-Based Assay for Detecting Antibodies Against Muscle-Specific Tyrosine Kinase in Myasthenia Gravis

Cited by 8 publications

References 29 publications

Development and Application of a Cell-Based Assay for LRP4 Antibody Associated With Myasthenia Gravis

Development and Application of a Cell-Based Assay for LRP4 Antibody Associated With Myasthenia Gravis

Immunotherapies in MuSK-positive Myasthenia Gravis; an IgG4 antibody-mediated disease

Predictors to Health Promoting Behaviors among Patients with Myasthenia Gravis: Health Belief Model Approach

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