Myasthenia gravis and neuromyelitis opica: A causal link

Comorbid Autoimmune Diseases in Patients With Myasthenia Gravis: A Retrospective Cross-Sectional Study of a Chinese Cohort

Introduction: The phenomenon of coexisting autoimmune diseases (ADs) in patients with myasthenia gravis (MG) has attracted considerable attention. However, few studies have investigated the burden and potential clinical associations of ADs in Chinese MG cohorts.

Methods: In this retrospective cross-sectional study, we reviewed the records of 1,132 patients with MG who were admitted to Huashan Hospital Fudan University from August 2013 to August 2020. Patients were excluded if they had incomplete medical records (n = 336).

Results: Comorbid ADs were found in 92 of 796 Chinese patients with MG (11.6%), among which, hyperthyroidism (6.7%), hypothyrosis (2.6%), and vitiligo (0.8%) were predominant. Patients with MG with ADs were predominantly female, younger at the onset of MG symptoms, and had a lower frequency of thymoma. Compared to the general population, we found a significantly higher percentage of hyperthyroidism (8.5-fold increase, p < 0.001), hypothyrosis (2.6-fold increase, p < 0.001), vitiligo (1.3-fold increase, p < 0.001), rheumatoid arthritis (1.4-fold increase, p < 0.001), immune thrombocytopenic purpura (193.1-fold increase, p < 0.001), autoimmune hemolytic anemia (7.4-fold increase, p < 0.001), autoimmune hepatitis (5.1-fold increase, p < 0.001), and polymyositis (11.5-fold increase, p < 0.001) in patients with MG with ADs. Patients with MG with ADs presented a lower proportion of previous history of MC (0 vs. 5.6%, p < 0.05) than those without ADs. The proportion of MGFA Class I at onset in patients with MG with ADs was significantly higher than that in patients with MG without ADs (77.0 vs. 52.7%, p < 0.05). The proportion of MuSK-positive in patients with MG with ADs was significantly lower than that in patients with MG without ADs (0 vs. 4.8%, p < 0.05).

Conclusion: In conclusion, we observed a higher frequency of concurrent ADs in a Chinese MG cohort. Furthermore, MG combined with ADs tended to have mild clinical presentation.

[Neuromyelitis Optica Spectrum Disorders - Present Insights and Recent Developments]

The achievements of the last 15 years have essentially shaped the diagnostic methods and therapy of Neuromyelitis optica spectrum disorders (NMOSD): from discovery of aquaporin 4 antibodies and further development of diagnostic criteria the path has led to the approval of eculizumab and satralizumab as first disease modifying treatments in Europe. This article should give an overview on the present insights and future treatment options.

Autoimmune diseases associated with Neuromyelitis Optica Spectrum Disorders: A literature review

INTRODUCTION

Neuromyelitis Optica (NMO) is an autoimmune inflammatory demyelinating disease of the central nervous system (CNS) which predominantly involves optic nerves and spinal cord. Since the introduction of Neuromyelitis Optica Spectrum Disorders (NMOSD) as a separate entity, there have been many reports on its association with other disorders including systemic and organ-specific autoimmune diseases. Here, we reviewed other immune-mediated diseases associated with NMOSD and tried to categorize them.

METHODS

The present review was conducted using the PUBMED database based on papers from 1976 (i.e., since the first NMO comorbidity with SLE was reported) to 2017. We included all articles published in English. The keywords utilized included Neuromyelitis optica, Neuromyelitis Optica Spectrum Disorders, Devic's disease, in combination with comorbidity or comorbidities.

RESULTS

Diseases with immune-based pathogenesis are the most frequently reported co-morbidities associated with NMOSD, most of which are antibody-mediated diseases. According to literature, Sjogren's Syndrome (SS) and Systemic Lupus Erythematosus (SLE) are the most frequently reported diseases associated with NMOSD among systemic autoimmune diseases. Further, myasthenia gravis in neurological and autoimmune thyroid diseases in non-neurological organ-specific autoimmune diseases are the most reported comorbidities associated with NMOSD in the literature.

CONCLUSIONS

NMOSD may be associated with a variety of different types of autoimmune diseases. Therefore, systemic or laboratory signs which are not typical for NMOSD should be properly investigated to exclude other associated comorbidities. These comorbidities may affect the treatment strategy and may improve the patients' care and management.

NMO-IgG and AQP4 Peptide Can Induce Aggravation of EAMG and Immune-Mediated Muscle Weakness

Neuromyelitis optica (NMO) and myasthenia gravis (MG) are autoimmune diseases mediated by autoantibodies against either aquaporin 4 (AQP4) or acetylcholine receptor (AChR), respectively. Recently, we and others have reported an increased prevalence of NMO in patients with MG. To verify whether coexisting autoimmune disease may exacerbate experimental autoimmune MG, we tested whether active immunization with AQP4 peptides or passive transfer of NMO-Ig can affect the severity of EAMG. Injection of either AQP4 peptide or NMO-Ig to EAMG or to naive mice caused increased fatigability and aggravation of EAMG symptoms as expressed by augmented muscle weakness (but not paralysis), decremental response to repetitive nerve stimulation, increased neuromuscular jitter, and aberration of immune responses. Thus, our study shows increased disease severity in EAMG mice following immunization with the NMO autoantigen AQP4 or by NMO-Ig, mediated by augmented inflammatory response. This can explain exacerbation or increased susceptibility of patients with one autoimmune disease to develop additional autoimmune syndrome.

Myasthenia gravis: a clinical-immunological update

Myasthenia gravis (MG) is the archetypic disorder of both the neuromuscular junction and autoantibody-mediated disease. In most patients, IgG1-dominant antibodies to acetylcholine receptors cause fatigable weakness of skeletal muscles. In the rest, a variable proportion possesses antibodies to muscle-specific tyrosine kinase while the remainder of seronegative MG is being explained through cell-based assays using a receptor-clustering technique and, to a lesser extent, proposed new antigenic targets. The incidence and prevalence of MG are increasing, particularly in the elderly. New treatments are being developed, and results from the randomised controlled trial of thymectomy in non-thymomatous MG, due for release in early 2016, will be of particular clinical value. To help navigate an evidence base of varying quality, practising clinicians may consult new MG guidelines in the fields of pregnancy, ocular and generalised MG (GMG). This review focuses on updates in epidemiology, immunology, therapeutic and clinical aspects of GMG in adults.