About this Research Topic
Myasthenia gravis (MG) is a rare antibody-mediated disease of the neuromuscular junction. Like other autoimmune conditions, it has a multifactorial etiology to which genes and environment both contribute. Pathogenic Abs targeting key end-plate components, mostly extracellular domains of post-synaptic proteins, are ultimately responsible for the neuromuscular transmission defect. The acetylcholine receptor (AChR), the muscle-specific tyrosine kinase (MuSK) and the low-density lipoprotein-related protein 4 (LRP4) are the main antigens in MG. Specific Abs identify disease subtypes with distinctive pathogenic aspects, clinical features and response to therapy. While Abs to the AChR are detected in approximately 85% of patients, MuSK Abs are present in around 4% of the whole MG population with differences across countries, and affected patients are predominantly female.
The possibility to detect, in patients negative on standard RIA, AChR and MuSK Abs by cell-based assays (CBAs) can significantly improve MG diagnosis. However, the sensitivity and specificity of these new assays are not yet defined as their use is limited to few laboratories and studies on large patient populations are lacking. In addition, the prevalence of LRP4 Abs in patients with neither AChR nor MuSK Abs (double seronegative -dSNMG) remains uncertain, given the limited sample size of most available studies and the use of different assay techniques. Lastly, a proportion of MG patients do not have detectable circulating Abs. The clinical characteristics in these cases are variable and diagnostic confirmation may be challenging.
Although most patients with MG respond satisfactorily to conventional treatment (anticholinesterases, steroids, immunosuppressants and, in selected subgroups, thymectomy), several needs remain unmet. Complete remission is rare, long-lasting treatment is required in most cases, and 10-15% of patients suffer from diseases relapses and remain dependent on high doses of steroids and immunosuppressants. Therapeutic thymectomy proved effective in adult subjects with generalized AChR-MG. Its role remains controversial in patients with purely ocular symptoms or juvenile onset. There is also considerable uncertainty on the management of mild MG forms and the utility of available biomarkers of disease activity.
While recent trials and prospective studies support the use of biologics in patients with unsatisfactory disease control, optimization of conventional treatment remains the standard-of-care used in the great majority of patients with MG. Outcome measures considering MG-related impairment and exposure to long-term immunosuppression, and tailored treatment strategies may considerably improve MG long-term prognosis and quality-of-life.
This Research Topic aims to provide an overview of current issues in MG management.
We welcome the submission of reviews and original articles addressing, but not limited to, the following themes:
· The use of new electrophysiological techniques and new antibody testing techniques in the diagnosis and management of MG.
· Key challenges in measuring clinical severity and outcome in MG.
· The role of biomarkers (antibodies, miRNAs, T cell and B cell subsets, EMG testing) in treatment planning and patient follow-up.
· Strategies in the management of selected patient subgroups (during pregnancy/lactation, MG in children, MG in the elderly, ocular MG, refractory MG).
· Current evidence for the use of therapeutic thymectomy in different patient subgroups.
· How physical exercise and diet can improve well-being in MG patients.
· New therapeutic options (including B-cell depletion, C5-inhibition, neonatal Fc receptor antagonists): when, in which cases and for how long?
Conflicts of Interest Declaration:
Dr. Jeffrey Guptill has received research grants and contracts: from: US NIH, NINDS (K23NS085049, HHSN27100001), NIAID (HHSN272201300017I), Myasthenia Gravis Foundation of America, the Grifols Foundation, the Alzheimer's Association, Ra Pharmaceuticals. He has also received personal compensation in the past year from Alexion, Kashiv, Argen-X, and Momenta, Inc for consulting services and from Grifols for educational activities.
Keywords: myasthenia gravis, anti-AChR antibody, anti-MuSK antibody, immunosuppression, thymectomy
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