Pathophysiology and immunological profile of myasthenia gravis and its subgroups

Myasthenia Gravis Mimicking Status Asthmaticus: The Hidden Crisis

Status asthmaticus is a severe form of aggravation of asthma, whereas myasthenia gravis (MG) is a rare neuromuscular condition characterised by exhaustion and muscle weakness. Myasthenic crisis can occasionally manifest with symptoms that resemble status asthmaticus, which can result in an incorrect diagnosis and ineffective therapy. In addition to discussing the therapeutic implications, this abstract attempts to draw attention to the difficulties in distinguishing between status asthmaticus and myasthenia crisis and the importance of diagnosing subtle signs of MG. In this case, we present a 55-year-old female, with a misdiagnosed case of bronchial asthma, who presented with shortness of breath at rest for two to three days and was suspected to have an acute exacerbating episode of asthma. She was later evaluated for non-respiratory causes of dyspnea on noticing subtle signs of ptosis and was found to have an active myasthenic crisis. Although this case presented typically as status asthmaticus, it did not respond to conventional treatment of it, and on the contrary, it worsened. Hence, it is necessary to look for subtle signs of MG and promptly differentiate it from other similar emergency events to help administer accurate treatment which can prove life-saving.

Disease-Based Prognostication: Myasthenia Gravis

Myasthenia gravis (MG) is an acquired autoimmune neuromuscular junction transmission disorder that clinically presents as fluctuating or persistent weakness in various skeletal muscle groups. Neuroprognostication in MG begins with some basic observations on the natural history of the disease and known treatment outcomes. Our objective is to provide a framework that can assist a clinician who encounters the MG patient for the first time and attempts to prognosticate probable outcomes in individual patients. In this review article, we explore clinical type, age of onset, antibody status, severity of disease, thymus pathology, autoimmune, and other comorbidities as prognostic factors in MG.

Autoimmune myasthenia gravis and COVID-19. A case report-based review

A potential relationship between COVID-19 infection and new onset myasthenia gravis (MG) has been suggested by the coexistence of these two diseases in a number of reports. This study aimed to assess their relationship by reviewing case studies of COVID-19 followed by new onset MG published between 01 December 2019 and 30 June 2023 identified by a search of PubMed/Medline database. In addition, we reviewed evidence in favour and against a potential cause and effect association, and described possible mechanisms that would underpin such a relationship. We identified 14 publications that reported 18 cases. Analysis showed the following features: age 19-83 years; 10 men/8 women; median time interval between COVID-19 and MG (17, 5-56 days); autoimmune comorbidities (4); generalised MG (14); ocular MG (4); thymoma (3); antiacetylcholine receptor antibody (16); antimuscle-specific kinase antibodies (2). All patients improved following treatment. Proof of direct causality between the two conditions can only be established in time by confirming epidemiological increase in the incidence of MG or elucidating pathogenic mechanisms to substantiate a possible cause-effect association, or both.

A decentralized, prospective, observational study to collect real-world data from patients with myasthenia gravis using smartphones

Introduction

We conducted a 3-month, prospective study in a population of patients with Myasthenia Gravis (MG), utilizing a fully decentralized approach for recruitment and monitoring (ClinicalTrials.gov Identifier: NCT04590716). The study objectives were to assess the feasibility of collecting real-world data through a smartphone-based research platform, in order to characterize symptom involvement during MG exacerbations.

Methods

Primary data collection included daily electronically recorded patient-reported outcomes (ePROs) on the presence of MG symptoms, the level of symptom severity (using the MG-Activities of Daily Living assessment, MG-ADL), and exacerbation status. Participants were also given the option to contribute data on their physical activity levels from their own wearable devices.

Results

The study enrolled and onboarded 113 participants across 37 US states, and 73% (N= 82) completed the study. The mean age of participants was 53.6 years, 60% were female. Participants were representative of a moderate to severe MG phenotype, with frequent exacerbations, high symptom burden and multiple comorbidities. 55% of participants (N=45) reported MG exacerbations during the study, with an average of 6.3 exacerbation days per participant. Median average MG-ADL scores for participants during self-reported exacerbation and non-exacerbation periods were 7 (interquartile range 4-9, range 1-19) and 0.3 (interquartile range 0-0.8, range 0-9), respectively. Analyses examining relationships between patient-reported and patient-generated health data streams and exacerbation status demonstrated concordance between self-reported MG-ADL scores and exacerbation status, and identified features that may be used to understand and predict the onset of MG symptom exacerbations, including: 1.) dynamic changes in day-to-day symptom reporting and severity 2.) daily step counts as a measure of physical activity and 3.) clinical characteristics of the patient, including the amount of time since their initial diagnosis and their active medications related to MG treatment. Finally, application of unsupervised machine learning methods identified unique clusters of exacerbation subtypes, each with their own specific representation of symptoms and symptom severity.

Conclusion

While these symptom signatures require further study and validation, our results suggest that digital phenotyping, characterized by increased multidimensionality and frequency of the data collection, holds promise for furthering our understanding of clinically significant exacerbations and reimagining the approach to treating MG as a heterogeneous condition.

Role of autoantibody levels as biomarkers in the management of patients with myasthenia gravis: A systematic review and expert appraisal

BACKGROUND AND PURPOSE

Although myasthenia gravis (MG) is recognized as an immunoglobulin G autoantibody-mediated disease, the relationship between autoantibody levels and disease activity in MG is unclear. We sought to evaluate this landscape through systematically assessing the evidence, testing the impact of predefined variables on any relationship, and augmenting with expert opinion.

METHODS

In October 2020, a forum of leading clinicians and researchers in neurology from across Europe (Expert Forum for Rare Autoantibodies in Neurology in Myasthenia Gravis) participated in a series of virtual meetings that took place alongside the conduct of a systematic literature review (SLR).

RESULTS

Forty-two studies were identified meeting inclusion criteria. Of these, 10 reported some correlation between a patient's autoantibody level and disease severity. Generally, decreased autoantibody levels (acetylcholine receptor, muscle-specific kinase, and titin) were positively and significantly correlated with improvements in disease severity (Quantitative Myasthenia Gravis score, Myasthenia Gravis Composite score, Myasthenia Gravis Activities of Daily Living score, Myasthenia Gravis Foundation of America classification). Given the limited evidence, testing the impact of predefined variables was not feasible.

CONCLUSIONS

This first SLR to assess whether a correlation exists between autoantibody levels and disease activity in patients with MG has indicated a potential positive correlation, which could have clinical implications in guiding treatment decisions. However, in light of the limited and variable evidence, we cannot currently recommend routine clinical use of autoantibody level testing in this context. For now, patient's characteristics, clinical disease course, and laboratory data (e.g., autoantibody status, thymus histology) should inform management, alongside patient-reported outcomes. We highlight the need for future studies to reach more definitive conclusions on this relationship.

Myasthenia gravis and congenital myasthenic syndromes

Myasthenia gravis is an autoimmune disorder caused by antibodies against elements in the postsynaptic membrane at the neuromuscular junction, which leads to muscle weakness. Congenital myasthenic syndromes are rare and caused by mutations affecting pre- or postsynaptic function at the neuromuscular synapse and resulting in muscle weakness. MG has a prevalence of 150-250 and an annual incidence of 8-10 individuals per million. The majority has disease onset after age 50 years. Juvenile MG with onset in early childhood is more common in East Asia. MG is subgrouped according to type of pathogenic autoantibodies, age of onset, thymus pathology, and generalization of muscle weakness. More than 80% have antibodies against the acetylcholine receptor. The remaining have antibodies against MuSK, LRP4, or postsynaptic membrane antigens not yet identified. A thymoma is present in 10% of MG patients, and more than one-third of thymoma patients develop MG as a paraneoplastic condition. Immunosuppressive drug therapy, thymectomy, and symptomatic drug therapy with acetylcholine esterase inhibitors represent cornerstones in the treatment. The prognosis is good, with the majority of patients having mild or moderate symptoms only. Most congenital myasthenic syndromes are due to dysfunction in the postsynaptic membrane. Symptom debut is in early life. Symptomatic drug treatment has sometimes a positive effect.

Paraneoplastic Syndromes in Neuro-Ophthalmology

Paraneoplastic neurological syndromes (PNS) occur in about 1 in 300 cases of cancer. The usual mechanism is that an antigen on the cancer sets off an immune response that then cross-reacts with a nervous system antigen. The presentation is usually with a subacute progressive neurological disorder. The management of these conditions is usually of both the underlying tumor and immunomodulation to suppress the autoimmune response. There are a number of these conditions that can present to the Neuro-Ophthalmology clinic, either as a discrete condition affecting vision or eye movements or as part of a more widespread neurological disorder. This article will discuss these conditions, their management and prognosis.

Long Non-Coding RNAs in the Cell Fate Determination of Neoplastic Thymic Epithelial Cells

Thymic Epithelial Tumors (TETs) arise from epithelial cells of the thymus and are very rare neoplasms comprising Thymoma, Thymic carcinoma, and Thymic Neuroendocrine tumors that still require in-depth molecular characterization. Long non-coding RNAs (lncRNAs) are emerging as relevant gene expression modulators involved in the deregulation of several networks in almost all types of human cancer, including TETs. LncRNAs act at different control levels in the regulation of gene expression, from transcription to translation, and modulate several pathways relevant to cell fate determination under normal and pathological conditions. The activity of lncRNAs is strongly dependent on their expression, localization, and post-transcriptional modifications. Starting from our recently published studies, this review focuses on the involvement of lncRNAs in the acquisition of malignant traits by neoplastic thymic epithelial cells, and describes the possible use of these molecules as targets for the design of novel therapeutic approaches specific for TET. Furthermore, the involvement of lncRNAs in myasthenia gravis (MG)-related thymoma, which is still under investigation, is discussed.

Quality of Life in Myasthenia Gravis and Correlation of MG-QOL15 with Other Functional Scales

Health-related quality of life (HRQOL) in myasthenia gravis (MG) is frequently decreased. Further, there are many validated clinical scales and questionnaires to evaluate the clinical status in MG. We aimed to determine if there was an improvement in HRQOL following an intensive treatment for MG, identify which demographic and clinical features influenced patients’ HRQOL, and investigate if the questionnaire MG-QOL15 correlated with other evaluation scales. We recruited 45 patients with generalised MG who were starting immunomodulatory treatment with intravenous immunoglobulins and prednisone for the first time. At each visit, we administered several validated scales for MG. The mean MG-QOL15 score improved significantly at 4 and 6 weeks of the study. Additionally, the MG-QOL15 score correlated strong with the Myasthenia Gravis-Activities of Daily Living (MG-ADL) and the Neuro-QOL Fatigue and weakest with the Quantitative Myasthenia Gravis Scoring System (QMG). The QMG score prior to study enrolment was associated with HRQOL. We observed that HRQOL in MG improved after receiving an intensive immunomodulatory treatment and achieving better control of the symptoms. The questionnaire MG-QOL15 correlated positively with other clinical measures. As MG is a fluctuating condition, and some symptoms are difficult to examine, we direct physicians toward the use of scales and questionnaires composed of items perceived by the patient.

Antibody Therapies in Autoimmune Neuromuscular Junction Disorders: Approach to Myasthenic Crisis and Chronic Management

Myasthenia gravis (MG) is a neurological autoimmune disorder characterized by muscle weakness and fatigue. It is a B cell-mediated disease caused by pathogenic antibodies directed against various components of the neuromuscular junction (NMJ). Despite the wide range of adverse effects, current treatment is still based on non-specific immunosuppression, particularly on long-term steroid usage. The increasing knowledge regarding the pathogenic mechanisms of MG has however allowed to create more target-specific therapies. A very attractive therapeutic approach is currently offered by monoclonal antibodies (mAbs), given their ability to specifically and effectively target different immunopathological pathways, such as the complement cascade, B cell-related cluster of differentiation (CD) proteins, and the human neonatal Fc receptor (FcRn). Up to now, eculizumab, a C5-directed mAb, has been approved for the treatment of generalized MG (gMG) and efgartigimod, a FcRn inhibitor, has just been approved by the U.S. Food and Drug Administration for the treatment of anti-acetylcholine receptor (AChR) antibody positive gMG. Other mAbs are currently under investigation with encouraging preliminary results, further enriching the new range of therapeutic possibilities for MG. This review article provides an overview of the present status of mAb-based therapies for MG, which offer an exciting promise for better outcomes by setting the basis of a precision medicine approach.

Studying the relationship between clinical features and mental health among late-onset myasthenia gravis patients

BACKGROUND

Mental disorders are common comorbidities among individuals with neurological diseases, and the prevalence of depressive and anxiety-related symptoms in newly referred patients at neurology outpatient clinics is high. There have been few studies on the mental health of patients with late-onset myasthenia gravis (MG).

AIM

To examine the relationship between clinical features and the mental health symptoms within late-onset MG patients.

METHODS

A total of 105 patients diagnosed with MG were recruited consecutively from a neuromuscular outpatient clinic between December 2020 and February 2021. Patients were classified into two groups: early-onset MG (age at onset < 50 years, n = 63) and late-onset MG (age at onset ≥ 50 years, n = 42). Social demographic data and information about marital status, education level, clinical symptoms, serum antibody levels, and therapies used were collected for all participants. Participants were also evaluated using the Myasthenia Gravis Composite scale, the Myasthenia Gravis Activities of Daily Living scale, the Myasthenia Gravis Quality of Life 15 (MG-QOL-15) questionnaire, the 17-item version of the Hamilton Depression Rating Scale (HAM-D) and the Hamilton Anxiety Rating Scale (HAM-A). The relationship between clinical features and mental health in late-onset MG patients was examined using multivariate logistic regression analyses.

RESULTS

Late-onset MG patients were more prone to dyspnea, had higher levels of serum anti-acetylcholine receptor antibodies, and higher total scores on the MG-QOL-15, HAM-D, and HAM-A questionnaires, than early-onset MG patients had (P < 0.05). Among those with late-onset MG, female patients had higher total HAM-D and HAM-A scores than male patients had (P < 0.05). High scores on the QOL-15 questionnaire were associated with higher incidences of anxiety and depression, and the association was found to be independent after adjusting for confounding risk factors. In the late-onset subgroup, the areas under the receiver operating characteristic curves for the MG-QOL-15 score-based diagnostic accuracy for anxiety and depression state were 0.816 (P = 0.001) and 0.983 (P < 0.001), respectively.

CONCLUSION

Higher MG-QOL-15 scores were a risk factor for anxiety and depression in late-onset MG, and women with late-onset MG were more likely to have anxiety and depression than men were.

Identification of genetic risk loci and prioritization of genes and pathways for myasthenia gravis: a genome-wide association study

Myasthenia gravis is a chronic autoimmune disease characterized by autoantibody-mediated interference of signal transmission across the neuromuscular junction. We performed a genome-wide association study (GWAS) involving 1,873 patients diagnosed with acetylcholine receptor antibody-positive myasthenia gravis and 36,370 healthy individuals to identify disease-associated genetic risk loci. Replication of the discovered loci was attempted in an independent cohort from the UK Biobank. We also performed a transcriptome-wide association study (TWAS) using expression data from skeletal muscle, whole blood, and tibial nerve to test the effects of disease-associated polymorphisms on gene expression. We discovered two signals in the genes encoding acetylcholine receptor subunits that are the most common antigenic target of the autoantibodies: a GWAS signal within the cholinergic receptor nicotinic alpha 1 subunit (CHRNA1) gene and a TWAS association with the cholinergic receptor nicotinic beta 1 subunit (CHRNB1) gene in normal skeletal muscle. Two other loci were discovered on 10p14 and 11q21, and the previous association signals at PTPN22, HLA-DQA1/HLA-B, and TNFRSF11A were confirmed. Subgroup analyses demonstrate that early- and late-onset cases have different genetic risk factors. Genetic correlation analysis confirmed a genetic link between myasthenia gravis and other autoimmune diseases, such as hypothyroidism, rheumatoid arthritis, multiple sclerosis, and type 1 diabetes. Finally, we applied Priority Index analysis to identify potentially druggable genes/proteins and pathways. This study provides insight into the genetic architecture underlying myasthenia gravis and demonstrates that genetic factors within the loci encoding acetylcholine receptor subunits contribute to its pathogenesis.

Competitive endogenous RNA network and pathway-based analysis of LncRNA single-nucleotide polymorphism in myasthenia gravis

Myasthenia gravis (MG) is a complex neurological autoimmune disease with a pathogenetic mechanism that has yet to be elucidated. Emerging evidence has revealed that genes, non-coding RNAs and genetic variants play significant roles in the pathogenesis of MG. However, the molecular mechanisms of single nucleotide polymorphisms (SNPs) located on lncRNAs could disturb lncRNA-mediated ceRNA regulatory functions still unclear in MG. In this study, we collated 276 experimentally confirmed MG risk genes and 192 MG risk miRNAs. We then constructed a lncRNA-mediated ceRNA network for MG based on multi-step computational strategies. Next, we systematically integrated risk pathways and identified candidate SNPs in lncRNAs for MG based on data acquired from public databases. In addition, we constructed a pathway-based lncRNA-SNP mediated network (LSPN) that contained 128 lncRNAs targeting 8 MG risk pathways. By analyzing network, we propose a latent mechanism for how the “lncRNA-SNP-mRNA-pathway” axis affects the pathogenesis of MG. Moreover, 25 lncRNAs and 51 SNPs on lncRNAs were extracted from the “lncRNA-SNP-mRNA-pathway” axis. Finally, functional analyses demonstrated lncRNA-SNPs mediated ceRNA regulation pairs associated with MG participated in the MAPK signaling pathway. In summary, we constructed MG-specific lncRNA-SNPs mediated ceRNA regulatory networks based on pathway in the present study, which was helpful to elucidate the roles of lncRNA-SNPs in the pathogenesis of MG and provide novel insights into mechanism of lncRNA-SNPs as potential genetic risk biomarkers of MG.

Risk Factors for Generalization in Patients with Ocular Myasthenia Gravis: A Multicenter Retrospective Cohort Study

Introduction

Many patients with ocular myasthenia gravis (OMG) progress to generalized disease within the first 2 years of the onset of ocular symptoms. Several retrospective studies have identified risk factors associated with generalization, however these studies included patients on immunosuppression therapy or those undergoing thymectomy, which may reduce the generalization risk. In this study we explored the risk factors for generalization in non-immunosuppressed and non-thymectomized patients with OMG.

Methods

Data from patients with OMG treated at seven tertiary hospitals in China were retrospectively reviewed. Clinical characteristics, including sex, age at onset, symptoms at onset, comorbid autoimmune diseases, neostigmine test response, repetitive nerve stimulation (RNS) findings, presence of serum anti-acetylcholine receptor antibody (AChR-Ab), and thymic status based on radiological and pathological studies, were collected. The main outcome measure was disease generalization. The follow-up period was defined as the date of ocular symptom onset to the date of confirmation of generalization or immunotherapy initiation, or last follow-up (defined as 60 months). The Cox proportional hazards model was used to assess the risk factors for generalization.

Results

Overall, 572 patients (269 women) were eligible for inclusion in the analysis, of whom 144 developed generalization. The mean (standard deviation) onset age was 45.5 (19.8) years, and the median (interquartile range) follow-up period was 14.5 (7.0–47.3) months. Multivariable Cox regression analysis demonstrated that both early-onset (adjusted hazard ratio [aHR] 5.34; 95% confidence interval [CI] 1.64–17.36; p = 0.005) and late-onset (aHR 7.18; 95% CI 2.22–23.27; p = 0.001) in adulthood, abnormal RNS findings (aHR 3.01; 95% CI 1.97–4.61; p < 0.001), seropositivity for AChR-Ab (aHR 2.58; 95% CI 1.26–5.26; p = 0.01), and thymoma (aHR 1.62; 95% CI 1.05–2.49; p = 0.03) were independently associated with increased risk of generalization.

Conclusion

The risk of generalization increased significantly in patients with adult-onset OMG, abnormal RNS findings, seropositivity for AChR-Ab, and thymoma, suggesting that these risk factors may predict OMG generalization.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40120-021-00292-x.

Feasibility study of respiratory function home monitoring for patients with Myasthenia Gravis

BACKGROUND

Myasthenia gravis (MG) is a rare and chronic autoimmune neuromuscular disease that causes weakness among skeletal muscles responsible for mobility and breathing. Individuals with MG who have difficulty breathing may need to schedule an emergent provider visit where a negative inspiratory force (NIF) measurement test is performed to measure respiratory strength.

PURPOSE

Examine the feasibility of individuals with MG to perform NIF respiratory function monitoring in the home setting and determine its impact on their perceived quality of life.

METHODS

This is a quantitative one-group pretest-posttest study of 30 individuals (18-75 years old) who carry the diagnosis of MG and have been stable with treatment for at least 30 days. Participants completed the Brunnsviken Brief Quality of Life Scale (BBQ-LS) and the System Usability Scale (SUS) prestudy. Participants were required to independently perform and record their NIF measurements twice daily for 14 days. After completing the 14 days, participants completed the BBQ-LS, SUS, and an end-of-study survey.

RESULTS

There was a significant difference in BBQ-LS scores at baseline (M = 62.97, SD = 17.84) and poststudy (M = 98.2, SD = 13.63) (t[29] = -5.39, p <.000). System Usability Scale scores were significantly different at baseline (M = 77.25, SD = 11.05) than at study completion (M = 94.42, SD = 5.64) (t[29], = -8.04, p = .000).

CONCLUSION

Study results indicate that it is feasible for individuals with MG to perform NIF readings in the home setting and demonstrated an increase in the perceived quality of life.

IMPLICATIONS

Future large-scale studies can help determine the adoption of handheld NIF monitoring at home for individuals with MG.

Clinical features and outcome of acquired myasthenia gravis in 94 dogs

Background

Factors known to be associated with outcome of acquired myasthenia gravis (MG) in dogs are limited.

Hypothesis/Objectives

Of dogs with MG, advancing age and comorbid neoplasia are associated with poor long‐term prognosis and low rates of remission.

Animals

Ninety‐four client‐owned dogs with MG diagnosed by acetylcholine receptor antibody (AChR Ab) assay between 2001 and 2019 from a university clinic and 3 private clinics in the United States.

Methods

Cases were retrospectively evaluated and data were collected to determine clinical signs, treatment, and response to therapy defined by means of a clinical scoring rubric. Immunological remission was defined as a return of the AChR Ab concentration to <0.6 nmol/L. Multivariable binary logistic regression analysis was used to identify clinical criteria predicting remission.

Results

An anticholinesterase drug was used to treat 90/94 (96%) dogs, which in 63/94 (67%) was the sole treatment; other drugs included immune modulators. Clinical remission (lack of clinical signs ≥4 weeks after treatment cessation) was observed in 29 (31% [95% confidence interval (CI): 22.4‐40.8%]) dogs, clinical response (lack of clinical signs on treatment) in 14 (15% [95% CI: 9.0‐23.6%]) dogs, clinical improvement (on treatment) in 24 (26% [95% CI: 17.8‐35.2%]) dogs, and no clinical improvement in 27 (29% [95% CI: 20.5‐38.6%]) dogs. Immunological remission was observed in 27/46 (59%) dogs, with clinical remission in all 27. Younger age (P = .04) and comorbid endocrine disease (P = .04) were associated with clinical remission. Initial AChR Ab concentration (P = .02) and regurgitation (P = .04) were negatively associated with clinical remission.

Conclusions and Clinical Importance

Clinical remission in MG is less likely in older dogs and dogs presenting with regurgitation or high initial AChR Ab concentration, but more likely in younger dogs and dogs with comorbid endocrine disease.

Next-Generation Sequencing Identifies Extended HLA Class I and II Haplotypes Associated With Early-Onset and Late-Onset Myasthenia Gravis in Italian, Norwegian, and Swedish Populations

Genetic susceptibility to myasthenia gravis (MG) associates with specific HLA alleles and haplotypes at the class I and II regions in various populations. Previous studies have only examined alleles at a limited number of HLA loci that defined only broad serotypes or alleles defined at the protein sequence level. Consequently, genetic variants in noncoding and untranslated HLA gene segments have not been fully explored but could also be important determinants for MG. To gain further insight into the role of HLA in MG, we applied next-generation sequencing to analyze sequence variation at eleven HLA genes in early-onset (EO) and late-onset (LO) non-thymomatous MG patients positive for the acetylcholine receptor (AChR) antibodies and ethnically matched controls from Italy, Norway, and Sweden. For all three populations, alleles and haplotype blocks present on the ancestral haplotype AH8.1 were associated with risk in AChR-EOMG patients. HLA-B*08:01:01:01 was the dominant risk allele in Italians (OR = 3.28, P = 1.83E-05), Norwegians (OR = 3.52, P = 4.41E-16), and in Swedes HLA-B*08:01 was the primary risk allele (OR = 4.24, P <2.2E-16). Protective alleles and haplotype blocks were identified on the HLA-DRB7, and HLA-DRB13.1 class II haplotypes in Italians and Norwegians, whereas in Swedes HLA-DRB7 exhibited the main protective effect. For AChR-LOMG patients, the HLA-DRB15.1 haplotype and associated alleles were significantly associated with susceptibility in all groups. The HLA-DR13-HLA-DR-HLA-DQ haplotype was associated with protection in all AChR-LOMG groups. This study has confirmed and extended previous findings that the immunogenetic predisposition profiles for EOMG and LOMG are distinct. In addition, the results are consistent with a role for non-coding HLA genetic variants in the pathogenesis of MG.

Fc-Receptor Targeted Therapies for the Treatment of Myasthenia gravis

Myasthenia gravis (MG) is an autoimmune disease in which immunoglobulin G (IgG) antibodies (Abs) bind to acetylcholine receptors (AChR) or to functionally related molecules in the postsynaptic membrane at the neuromuscular junction. IgG crystallizable fragment (Fc)-mediated effector functions, such as antibody-dependent complement deposition, contribute to disease development and progression. Despite progress in understanding Ab-mediated disease mechanisms, immunotherapy of MG remained rather unspecific with corticosteroids and maintenance with immunosuppressants as first choice drugs for most patients. More specific therapeutic IgG Fc-based platforms that reduce serum half-life or effector functions of pathogenic MG-related Abs are currently being developed, tested in clinical trials or have recently been successfully translated into the clinic. In this review, we illustrate mechanisms of action and clinical efficacies of emerging Fc-mediated therapeutics such as neonatal Fc receptor (FcRn)-targeting agents. Furthermore, we evaluate prospects of therapies targeting classical Fc receptors that have shown promising therapeutic efficacy in other antibody-mediated conditions. Increased availability of Fc- and Fc receptor-targeting biologics might foster the development of personalized immunotherapies with the potential to induce sustained disease remission in patients with MG.

Inhibitors of Cholinesterases in Pharmacology: the Current Trends

Inhibitors of cholinesterases are a wide group of low molecular weight compounds with a significant role in the current pharmacology. Besides the pharmacological importance, they are also known as toxic compounds like military nerve agents. In the pharmacology, drugs for Alzheimer disease, myasthenia gravis and prophylaxis of poisoning by nerve agents can be mentioned as the relevant applications. Besides this, anti-inflammation and antiphrastic drugs are other pharmacological applications of these inhibitors. This review is focused on a survey of cholinesterase inhibitors with known or expected pharmacological impact and indications of their use. Recent literature with comments is provided here as well.

Leflunomide ameliorates experimental autoimmune myasthenia gravis by regulating humoral and cellular immune responses

Leflunomide, an immunosuppressive disease-modifying anti-rheumatic drug (DMARD), is widely used in the treatment of rheumatoid arthritis (RA), psoriatic arthritis (PA) as well as multiple sclerosis. However, its role in myasthenia gravis (MG) has not yet been clearly explored. Here, we investigated the effect of leflunomide on experimental autoimmune myasthenia gravis (EAMG) in vivo and in vitro. The results demonstrated that leflunomide alleviated the severity of EAMG associated with reduced serum total anti-acetylcholine receptor (AChR) IgG levels. During the development of EAMG, the increase of follicular helper T cells (Tfh) 1, Tfh 17 cells and decrease of follicular regulatory T cells (Tfr) were reversely altered after leflunomide administration. Our work further found that leflunomide might inhibit Tfh cells through the IL-21/STAT3 pathway to reduce the secretion of antibodies by B cells. In addition, leflunomide rebuilt the balance of Th1/Th2/Th17/Treg subsets. These results suggested that leflunomide ameliorated EAMG severity by regulating humoral immune responses and Th cell profiles thereby providing a novel effective treatment strategy for MG.

Thymus and autoimmunity

The thymus prevents autoimmune diseases through mechanisms that operate in the cortex and medulla, comprising positive and negative selection and the generation of regulatory T-cells (Tregs). Egress from the thymus through the perivascular space (PVS) to the blood is another possible checkpoint, as shown by some autoimmune/immunodeficiency syndromes. In polygenic autoimmune diseases, subtle thymic dysfunctions may compound genetic, hormonal and environmental cues. Here, we cover (a) tolerance-inducing cell types, whether thymic epithelial or tuft cells, or dendritic, B- or thymic myoid cells; (b) tolerance-inducing mechanisms and their failure in relation to thymic anatomic compartments, and with special emphasis on human monogenic and polygenic autoimmune diseases and the related thymic pathologies, if known; (c) polymorphisms and mutations of tolerance-related genes with an impact on positive selection (e.g. the gene encoding the thymoproteasome-specific subunit, PSMB11), promiscuous gene expression (e.g. AIRE, PRKDC, FEZF2, CHD4), Treg development (e.g. SATB1, FOXP3), T-cell migration (e.g. TAGAP) and egress from the thymus (e.g. MTS1, CORO1A); (d) myasthenia gravis as the prototypic outcome of an inflamed or disordered neoplastic ‘sick thymus’.

Nocardiosis-an uncommon infection in patients with myasthenia gravis: report of three cases and review of literature

Nocardiosis is a rare infection in patients with myasthenia gravis (MG). We identified three cases of MG admitted with nocardiosis in our unit. We performed systematic literature search of previous publications and identified 18 patients. This paper presents three patients and reviews the clinical characteristics of 21 patients. The first case was a 69-year-old woman with thymomatous MG who presented with pustules and left lower limb pain. Evaluation showed osteomyelitis of the pubic ramus and ileopsoas abscess. The second case was a 54-year-old man who presented in myasthenic crisis due to pulmonary nocardiosis. The third case was a 48-year-old man with thymomatous MG who presented with lung abscess. All of them recovered completely after treatment with co-trimoxazole. Analysis of the 21 patients identified four risk factors for nocardiosis in MG: elderly men; thymoma; immunosuppressant medication, mainly steroid therapy; and pre-existing lung disease. Lungs was the most common site of infection. Suppurative disease was common manifestation regardless of organ involved. Clinical course is not unfavourable.

Immunopathology of Autoimmune Myasthenia Gravis: Implications for Improved Testing Algorithms and Treatment Strategies

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.

Myasthenia gravis, atypical polyneuropathy and multiple autoimmune phenomena in the same patient, with HLA-immunogenetic profile expectable for Greek chronic inflammatory demyelinating polyneuropathy: a case report

PURPOSE

The comorbidity of myasthenia gravis (MG), with other autoimmune disorders like systemic lupus erythematosus (SLE), is relatively frequent but the co-occurrence with chronic inflammatory demyelinating polyneuropathy (CIDP) along with various autoimmune manifestations in the absence of thymoma is of extreme rarity. Our aim is to report a case of a woman who presented the concomitant appearance of MG, axonal sensory-motor polyneuropathy and hepatitis that may indicate an underlying pathogenetic link among the different autoimmune disorders.

MATERIALS AND METHODS/RESULTS

We present a case of a 54-year-old woman, with a generalized MG and a chronic sensory-motor polyneuropathy, hypothyroidism, anaemia, hepatitis, livedo reticularis and facial flush, of assumed autoimmune background, like SLE, although with persistent negative ANA antibodies, from the beginning and through the whole following years. The Human Leukocyte Antigen (HLA)-DRB1 genotyping showed a profile of alleles (DRB1*11:01/11:04) compatible with CIDP of mainly female gender in Greece and frequencies close to those of Sjogren's syndrome and scleroderma's in the Greek population. The diagnostic problems, the atypical clinical, electrophysiological and immunological features are discussed, along with the rarity of the case, with this exceptional combination of autoimmune manifestations, which could be truly associated under the clinical umbrella of a systemic disease, like SLE. However, our patient did not ever fulfil the SLE criteria.

CONCLUSIONS

To raise awareness among clinicians about the exceptional combination of autoimmune manifestations driven by a specific HLA background.

C3, C5a and anti-acetylcholine receptor antibody as severity biomarkers in myasthenia gravis

Background

Although the pathogenesis of myasthenia gravis (MG) is well known, prognostic markers are not yet available. We assessed the utility of anti-acetylcholine receptor (AChR) antibody (AChR-ab) titer and concentration of C3, C4, and C5a as potential severity biomarkers in MG.

Methods

Levels of C3, C4, C5a, and AChR-ab were measured in 60 AChR-ab-positive patients with MG. Their relationship with clinical severity was analyzed using the activities of daily living (ADL) and MG composite (MGC) scales.

Results

AChR-ab titer correlated with severity of MG according to ADL (p = 0.002) and MGC scales (p = 0.001). When patients were classified according to disease duration, a statistically significant correlation between AChR-ab titer and clinical severity was only found in the subgroup of patients with fewer than 5 years from symptoms onset. C5a levels showed a positive correlation with MG severity according to the ADL scale (p = 0.041; τb = 0.18), although C5a levels were not different from the control group.

Discussion

AChR-ab titers and C5a levels could potentially be considered markers of severity in patients with MG.

Myasthenia Gravis and Congenital Myasthenic Syndromes

PURPOSE OF REVIEW

Myasthenia gravis (MG) is an autoimmune neuromuscular disease that causes fluctuating weakness in ocular, bulbar, and limb muscles and can, in 15% of cases, cause myasthenic crisis, a neurologic emergency characterized by respiratory failure. Although infrequent, MG needs to be promptly recognized and treated because the potential for improvement and remission is very high. The diagnosis of MG can be challenging and delayed because of the fluctuating nature of muscle weakness and the overlap of signs and symptoms with other neuromuscular diseases.This article reviews the importance of prompt recognition of the typical signs and symptoms, best tests to confirm the diagnosis, currently available acute and chronic treatment modalities, the role of thymectomy, and the natural history of the disease. Special consideration related to the diagnosis and management in women during pregnancy and in children will also be reviewed. This article also includes an overview of congenital myasthenic syndromes.

RECENT FINDINGS

Recent significant efforts in standardizing and improving the care of patients with MG have occurred, as well as new momentum in developing new drugs for patients with MG who do not adequately respond to currently available treatments. The number of clinical trials and drugs in development for MG is steadily increasing. Eculizumab has been recently approved by the US Food and Drug Administration (FDA) for adult patients with generalized MG who are acetylcholine receptor-antibody positive, based on the REGAIN (Safety and Efficacy of Eculizumab in Refractory Generalized Myasthenia Gravis) study, a phase 3, randomized, double-blind, placebo-controlled, multicenter trial. An international, multicenter, randomized trial comparing thymectomy plus prednisone with prednisone alone has demonstrated that thymectomy improves clinical outcome in patients with nonthymomatous MG. Clinical care guidelines have been published, and the recommendations for clinical research standards and the Myasthenia Gravis Foundation of America MGFA clinical classification published in 2000 have become widely accepted by the clinical and research community of MG experts.

SUMMARY

MG is a highly treatable disease with many effective treatment modalities available and with a natural history that continues to improve thanks to better diagnostic tests and effective drugs. The diagnosis and management of patients affected by MG can be highly rewarding for any neurologist as most patients are able to live normal lives if treated appropriately. Nevertheless, future research is needed to address unresolved clinical issues, such as when and how to discontinue immunosuppressive medications in patients in remission, the role and timing of thymectomy in children, and better treatment options for refractory patients.

The Muscle Is Not a Passive Target in Myasthenia Gravis

Myasthenia gravis (MG) is a rare autoimmune disease mediated by pathogenic antibodies (Ab) directed against components of the neuromuscular junction (NMJ), mainly the acetylcholine receptor (AChR). The etiological mechanisms are not totally elucidated, but they include a combination of genetic predisposition, triggering event(s), and hormonal components. MG disease is associated with defective immune regulation, chronic cell activation, inflammation, and the thymus is frequently abnormal. MG is characterized by muscle fatigability that is very invalidating and can be life-threatening when respiratory muscles are affected. MG is not cured, and symptomatic treatments with acetylcholinesterase inhibitors and immunosuppressors are life-long medications associated with severe side effects (especially glucocorticoids). While the muscle is the ultimate target of the autoimmune attack, its place and role are not thoroughly described, and this mini-review will focus on the cascade of pathophysiologic mechanisms taking place at the NMJ and its consequences on the muscle biology, function, and regeneration in myasthenic patients, at the histological, cellular, and molecular levels. The fine structure of the synaptic cleft is damaged by the Ab binding that is coupled to focal complement-dependent lysis in the case of MG with anti-AChR antibodies. Cellular and molecular reactions taking place in the muscle involve several cell types as well as soluble factors. Finally, the regenerative capacities of the MG muscle tissue may be altered. Altogether, the studies reported in this review demonstrate that the muscle is not a passive target in MG, but interacts dynamically with its environment in several ways, activating mechanisms of compensation that limit the pathogenic mechanisms of the autoantibodies.

CXCR5-negative natural killer cells ameliorate experimental autoimmune myasthenia gravis by suppressing follicular helper T cells

Background

Recent studies have demonstrated that natural killer (NK) cells can modulate other immune components and are involved in the development or progression of several autoimmune diseases. However, the roles and mechanisms of NK cells in regulating experimental autoimmune myasthenia gravis (EAMG) remained to be illustrated.

Methods

To address the function of NK cells in experimental autoimmune myasthenia gravis in vivo, EAMG rats were adoptively transferred with splenic NK cells. The serum antibodies, and splenic follicular helper T (Tfh) cells and germinal center B cells were determined by ELISA and flow cytometry. The roles of NK cells in regulating Tfh cells were further verified in vitro by co-culturing splenocytes or isolated T cells with NK cells. Moreover, the phenotype, localization, and function differences between different NK cell subtypes were determined by flow cytometry, immunofluorescence, and ex vivo co-culturation.

Results

In this study, we found that adoptive transfer of NK cells ameliorated EAMG symptoms by suppressing Tfh cells and germinal center B cells. Ex vivo studies indicated NK cells inhibited CD4⁺ T cells and Tfh cells by inducing the apoptosis of T cells. More importantly, NK cells could be divided into CXCR5^- and CXCR5⁺ NK subtypes according to the expression of CXCR5 molecular. Compared with CXCR5^- NK cells, which were mainly localized outside B cell zone, CXCR5⁺ NK were concentrated in the B cell zone and exhibited higher expression levels of IL-17 and ICOS, and lower expression level of CD27. Ex vivo studies indicated it was CXCR5^- NK cells not CXCR5⁺ NK cells that suppressed CD4⁺ T cells and Tfh cells. Further analysis revealed that, compared with CXCR5^- NK cells, CXCR5⁺ NK cells enhanced the ICOS expression of Tfh cells.

Conclusions

These findings highlight the different roles of CXCR5^- NK cells and CXCR5⁺ NK cells. It was CXCR5^- NK cells but not CXCR5⁺ NK cells that suppressed Tfh cells and inhibited the autoimmune response in EAMG models.

iTRAQ-Based Proteomics Analysis of Plasma of Myasthenia Gravis Patients Treated with Jia Wei Bu Zhong Yi Qi Decoction

Myasthenia gravis (MG) is an autoimmune disease. A proportion of MG patients did not get satisfactory results after treatment with pyridostigmine and prednisone. Jia Wei Bu Zhong Yi Qi (Jia Wei BZYQ) decoction, a water extract from multiple herbs, has been demonstrated to be effective in the treatment of multiple "Qi deficiency type" diseases including MG in China. In this text, we investigated protein alterations in the plasma from healthy volunteers (C), MG patients without any treatment (T1), MG patients with routine western medical treatment (T2), and MG patients with combined treatments of Jia Wei BZYQ decoction and routine western medicines (T3) and identified some potential proteins involved in the pathogenesis and treatment of MG. iTRAQ (isobaric tags for relative and absolute quantitation) and 2D-LC-MS/MS (two-dimensional liquid chromatography-tandem mass spectrometry technologies) were employed to screen differentially expressed proteins. The identification, quantification, functional annotation, and interaction of proteins were analyzed by matching software and databases. In our project, 618 proteins were identified, among which 447 proteins had quantitative data. The number of differentially expressed proteins was 110, 117, 143, 115, 86, and 158 in T1 vs. C, T2 vs. C, T2 vs. T1, T3 vs. C, T3 vs. T1, and T3 vs. T2 groups, respectively. Functional annotation results showed that many differentially expressed proteins were closely associated with immune responses. For instance, some key proteins such as C-reactive protein, apolipoprotein C-III, apolipoprotein A-II, alpha-actinin-1, and thrombospondin-1 have been found to be abnormally expressed in T3 group compared to T1 group or T2 group. Interaction network analyses also provided some potential biomarkers or targets for MG management.

Molecular profiling of thymoma with myasthenia gravis: Risk factors of developing myasthenia gravis in thymoma patients

OBJECTIVE

Thymoma is a rare epithelial tumor arising from the thymus in the anterior mediastinum. Nearly 50% of patients with thymoma develop myasthenia gravis, which is an indication of a poor long-term prognosis. Here, we identified specific and effective molecular markers for predicting in the development of myasthenia gravis patients with thymoma.

MATERIAL AND METHODS

We investigated molecular profiling based on RNA-sequencing (RNA-seq) for myasthenia gravis development in patients with thymoma. RNA was extracted from 34 patients with thymoma, 16 of whom had myasthenic and 18 of whom did not, and transcriptome profiles were analyzed through next-generation sequencing.

RESULTS

We discovered 140 differential expressed genes associated with myasthenia gravis in thymoma patients. The four genes, hypoxia-inducible factor 3 alpha (HIF3A), insulin-like growth factor-binding protein 1, pyruvate dehydrogenase kinase, and Krüppel-like factor 15 were differentially expressed in patients with thymoma who has myasthenia gravis and were validated by quantitative polymerase chain reaction. HIF3A expression was significantly higher in patients with myasthenia gravis than in those without.

CONCLUSION

HIF3A is aberrantly expressed in patient with thymoma who has myasthenia gravis and may be involved in the development of myasthenia gravis in thymoma patient.

Myasthenia gravis: Historical achievements and the "golden age" of clinical trials

Since the death of Chief Opechankanough >350 years ago, the myasthenia gravis (MG) community has gained extensive knowledge about MG and how to treat it. This review highlights key milestones in the history of treatment and discusses the current "golden age" of clinical trials. Although originally thought by many clinicians to be a disorder of hysteria and fluctuating weakness without observable cause, MG is one the most understood autoimmune neurologic disorders. However, studying it in clinical trials has been challenging due to the fluctuating nature of the medical condition which impacts MG clinical outcomes. Clinical trials must also account for the possibility of a placebo effect. Because MG is a rare incurable autoimmune disorder, it limits the number of potential patients available to participate in clinical trials. In the last 15 years, however, significant progress has been made with MG randomized clinical trials, resulting in a new drug (eculizumab) for physicians' treatment repertoire and an old technique (thymectomy) confirmed effective for MG. Some of the therapies (eg, thymectomy, corticosteroids, plasma exchange, and intravenous immunoglobulin [IVIg]) have survived the test of time. Others (eg, eculizumab and neonatal Fc receptor inhibitor) are novel and hold promise.

Thymoma mimicking an aortic aneurysm: always expect the unexpected

Thymic epithelial tumours (TETs) are rare lesions that represent less than 1% of all malignancies in adults. Presentation occurs in three ways: asymptomatic, with local thoracic symptoms or with paraneoplastic symptoms. Heterotopic ossifications are rare histological features in neoplasms and non-neoplastic lesions. Here, we present a 49-year-old male patient with a thymoma type B2 mimicking an aortic aneurysm. Alongside the thymoma, a cholesterol granuloma with unusual ossification features was found as well. This clinical presentation and pathological diagnosis are unusual findings.

A Rare Association between Myasthenia Gravis and a Growth Hormone Secreting Pituitary Macroadenoma: A Single Case Report

Myasthenia Gravis (MG) is a chronic autoimmune neuromuscular disease. Although it is well known that patients with myasthenia gravis have a higher incidence of other autoimmune disorders, however, its association with pituitary adenomas is extremely rare. We believe that our case represents the 8th of this association and the 2nd case involving a GH-secreting adenoma. Here we report a case of a 45-year old Syrian woman who presented with typical complaints of myasthenia gravis as she was suffering from variable painless and effort-related dysphagia and dysarthria. Her complaints became more evident at the end of the day, while acromegaly only manifested as a 4-month history of headache and a special facies that was noted by the physician. Brain MRI scan demonstrated a 3.21 x 2.42 x 2.35 cm pituitary mass for which the patient underwent a trans-sphenoidal pituitary tumor resection. In addition, postoperative histopathological investigations confirmed the diagnosis of a GH-secreting macroadenoma. On following up, it was observed that her myasthenic symptoms improved significantly on Pyridostigmin and Prednisolone. In conclusion, the presence of headache in a myasthenic patient should raise the attention for other underlying causes including pituitary tumors.

Autoimmune Channelopathies at Neuromuscular Junction

The neuromuscular junction, also called myoneural junction, is a site of chemical communication between a nerve fiber and a muscle cell. There are many types of channels at neuromuscular junction that play indispensable roles in neuromuscular signal transmission, such as voltage-gated calcium channels and voltage-gated potassium channels on presynaptic membrane, and acetylcholine receptors on post-synaptic membrane. Over the last two decades, our understanding of the role that autoantibodies play in neuromuscular junction disorders has been greatly improved. Antibodies against these channels cause a heterogeneous group of diseases, such as Lambert-Eaton syndrome, Isaacs' syndrome and myasthenia gravis. Lambert-Eaton syndrome is characterized by late onset of fatigue, skeletal muscle weakness, and autonomic symptoms. Patients with Isaacs' syndrome demonstrate muscle cramps and fasciculation. Myasthenia gravis is the most common autoimmune neuromuscular junction channelopathy characterized by fluctuation of muscle weakness. All these disorders have a high risk of tumor. Although these channelopathies share some common features, they differ for clinical features, antibodies profile, neurophysiological features, and treatments. The purpose of this review is to give a comprehensive insight on recent advances in autoimmune channelopathies at the neuromuscular junction.

Myasthenia gravis and pregnancy: retrospective evaluation of 27 pregnancies in a tertiary center and comparison with previous studies

BACKGROUND AND AIM

To share our experience with the management of pregnancies in women with myasthenia gravis (MG) in a tertiary center.

METHODS

The study retrospectively evaluated 27 pregnancies in 12 patients. The pregnancies were divided into 3 groups on the basis of the clinical course of MG during pregnancy: improvement (n = 7), disease-stable (n = 9), and deterioration (n = 11). The groups were compared with respect to patient characteristics, clinical features, and obstetric outcomes.

RESULTS

There were 4 miscarriages (14.8%), 3 preterm births (11.1%), and 4 cases of preterm premature rupture of the membranes (PPROM) (14.8%). Exacerbation was observed in 25.9% of the cases; the remission rate during the postpartum period and after miscarriage was 37%. The cesarean section (CS) rate was 78.3%. Pregnancies with deterioration of MG were statistically more likely to have higher miscarriage, preterm birth, PPROM, CS, and transient neonatal MG rates, in addition to a lower gestational age at birth, birth weight, and 5-min Apgar score than pregnancies with improved or stable disease (p values < 0.001, 0.04, 0.03, 0.009, 0.02, < 0.001, 0.002, and 0.043, respectively).

CONCLUSION

Physicians who manage pregnant women with MG must be familiar with the clinical features of the condition; a multidisciplinary approach is necessary for a better prognosis.

Myasthenia gravis

Myasthenia gravis (MG) is an autoimmune disease caused by antibodies against the acetylcholine receptor (AChR), muscle-specific kinase (MuSK) or other AChR-related proteins in the postsynaptic muscle membrane. Localized or general muscle weakness is the predominant symptom and is induced by the antibodies. Patients are grouped according to the presence of antibodies, symptoms, age at onset and thymus pathology. Diagnosis is straightforward in most patients with typical symptoms and a positive antibody test, although a detailed clinical and neurophysiological examination is important in antibody-negative patients. MG therapy should be ambitious and aim for clinical remission or only mild symptoms with near-normal function and quality of life. Treatment should be based on MG subgroup and includes symptomatic treatment using acetylcholinesterase inhibitors, thymectomy and immunotherapy. Intravenous immunoglobulin and plasma exchange are fast-acting treatments used for disease exacerbations, and intensive care is necessary during exacerbations with respiratory failure. Comorbidity is frequent, particularly in elderly patients. Active physical training should be encouraged.

Autoantibodies in acquired myasthenia gravis: Clinical phenotype and immunological correlation

BACKGROUND

Data on antibody profile in myasthenia gravis (MG) from India are limited.

OBJECTIVES

To investigate antibody profile in patients with MG and their clinical correlates.

PATIENTS AND METHODS

Patients of MG (n = 85, M:F::1.1:1, mean age: 39.29 ± 17.3 years, mean symptom duration: 72.94 ± 91.8 months) were evaluated for clinical features, MG foundation of America (MGFA) score, response to treatment, and outcome at last follow-up. Antibodies to acetylcholine receptor (AChR), muscle-specific kinase (MUSK), titin and ryanodine receptor (RYR) were analysed using ELISA.

RESULTS

Based on the regional distribution of weakness, the cohort could be categorized as: generalized: 60, ocular: 16 and oculo-bulbar: 9. Sixty patients were followed up for a mean duration of 26.74 ± 13.8 months. Outcome at last follow-up was as follows: remission-22, no remission-33 and dead-5. AChR and MUSK antibodies were detected in 58 and 8 patients, respectively. Frequency of generalized MG, worse MGFA score during the disease course and thymomatous histology significantly correlated with presence of AChR-antibodies, though outcome at last follow-up was comparable between AChR-antibody positive and negative groups. Patients with MUSK antibodies had oculo-bulbar or generalized MG and frequent respiratory crisis, but majority improved or remitted with treatment. Titin antibodies were detected in 31.8% and RYR antibodies in 32.9%. Their presence did not correlate with age at onset of MG, severity or presence of thymoma.

CONCLUSION

This report highlights the spectrum of antibodies in MG in an Indian cohort. AChR-antibody positivity correlated with clinical severity. Outcome was good in majority of MUSK antibody-positive MG. The role of other antibodies, complementary vs epiphenomenon, remains open.

Antibody profile may predict outcome in ocular myasthenia gravis

An unsolved issue remains whether there are clinical and immunological features to predict in a single patient the risk of conversion from ocular Myasthenia Gravis (OMG) to generalized disease (GMG) as 50-60% of patients may progress within 1-2 years since onset. Anti-acetylcholine receptor antibodies (AChR Abs) are found in up to 50% of OMG patients; muscle-specific tyrosine kinase antibodies (MuSK-Abs) are present in about 70% of the whole seronegative (SN), who usually develop a severe disease with bulbar involvement. We surveyed a cohort of 175 OMG patients with purely ocular symptoms and we compare the outcome of patients with antibodies to AChR or to MuSK with those seronegative for both Abs (DSN). All patients had purely ocular signs for at least 24 months. Gender, age at onset, time to generalization or to worsening in quantitative ocular QMG scores, electrophysiological results were analyzed. Males were 58.9%, females 41.1%. Patients with late onset of symptoms after 50 years (LOMG) were 78.3%. We assayed anti-MuSK-Abs in 4.7%, anti-AChR Abs in 38.5%; 57.3% were defined DSN. Thirty-seven patients (21.1%) progressed to GMG during the observational time: 23 were females, 62% of the whole group of the generalized subjects, 75% of MuSK-positive OMG converted to GMG versus the 26.2% of AChR positive and 13.7% of DSN. Statistical analysis showed that gender and presence of antibodies either to AChR or to MuSK were independent predictors of worse outcome; the DSN subjects had lower risk of conversion to GMG.

Advances in autoimmune myasthenia gravis management

INTRODUCTION

Myasthenia gravis (MG) is an autoimmune neuromuscular disorder with no cure and conventional treatments limited by significant adverse effects and variable benefit. In the last decade, therapeutic development has expanded based on improved understanding of autoimmunity and financial incentives for drug development in rare disease. Clinical subtypes exist based on age, gender, thymic pathology, autoantibody profile, and other poorly defined factors, such as genetics, complicate development of specific therapies. Areas covered: Clinical presentation and pathology vary considerably among patients with some having weakness limited to the ocular muscles and others having profound generalized weakness leading to respiratory insufficiency. MG is an antibody-mediated disorder dependent on autoreactive B cells which require T-cell support. Treatments focus on elimination of circulating autoantibodies or inhibition of effector mechanisms by a broad spectrum of approaches from plasmapheresis to B-cell elimination to complement inhibition. Expert commentary: Standard therapies and those under development are disease modifying and not curative. As a rare disease, clinical trials are challenged in patient recruitment. The great interest in development of treatments specific for MG is welcome, but decisions will need to be made to focus on those that offer significant benefits to patients.

Myasthenia gravis as a prognostic marker in patients with thymoma

Background

Thymoma is the most common mediastinal tumor, representing <1% of all cancers. It is usually associated with paraneoplastic disorders, mainly myasthenia gravis (MG). The aim of the present study was to describe patients with thymoma and the differences between those with MG and those without it.

Methods

A retrospective 10-year database of the patients with thymoma treated at a single cancer referral hospital (National Institute of Cancer, Mexico City), was analyzed.

Results

Sixty-four files from patients with thymoma were analyzed, 18 of them had MG. The symptoms that occurred most frequently in patients with MG were ptosis, diplopia, appendicular weakness, dysphonia and dysphagia. The most frequent Myasthenia Gravis Foundation of America (MGFA) stage was IIIb followed by stage I. Almost all the patients with MG had positive Acetylcholine Receptor antibodies (P<0.001), with not specified antibodies in four patients. The median overall survival showed a trend to be higher among the patients with MG, but there were no significant differences.

Conclusions

In patients with thymoma MG manifests with different clinical and autoimmune traits, but not survival differences. A larger multi-centric study should be encouraged to evaluate the prognostic implications of having MG in patients with thymoma.

Immunopathogenesis in Myasthenia Gravis and Neuromyelitis Optica

Myasthenia gravis (MG) and neuromyelitis optica (NMO) are autoimmune channelopathies of the peripheral neuromuscular junction (NMJ) and central nervous system (CNS) that are mainly mediated by humoral immunity against the acetylcholine receptor (AChR) and aquaporin-4 (AQP4), respectively. The diseases share some common features, including genetic predispositions, environmental factors, the breakdown of tolerance, the collaboration of T cells and B cells, imbalances in T helper 1 (Th1)/Th2/Th17/regulatory T cells, aberrant cytokine and antibody secretion, and complement system activation. However, some aspects of the immune mechanisms are unique. Both targets (AChR and AQP4) are expressed in the periphery and CNS, but MG mainly affects the NMJ in the periphery outside of CNS, whereas NMO preferentially involves the CNS. Inflammatory cells, including B cells and macrophages, often infiltrate the thymus but not the target—muscle in MG, whereas the infiltration of inflammatory cells, mainly polymorphonuclear leukocytes and macrophages, in NMO, is always observed in the target organ—the spinal cord. A review of the common and discrepant characteristics of these two autoimmune channelopathies may expand our understanding of the pathogenic mechanism of both disorders and assist in the development of proper treatments in the future.