Reduced plasmablast frequency is associated with seronegative myasthenia gravis

Advancements and prospects of novel biologicals for myasthenia gravis: toward personalized treatment based on autoantibody specificities

Myasthenia gravis (MG) is an antibody-mediated autoimmune disease with a prevalence of 150-250 cases per million individuals. Autoantibodies include long-lived antibodies against the acetylcholine receptor (AChR), mainly of the IgG1 subclass, and IgG4, produced almost exclusively by short-lived plasmablasts, which are prevalent in muscle-specific tyrosine kinase (MuSK) myasthenia gravis. Numerous investigations have demonstrated that MG patients receiving conventional medication today still do not possess satisfactory symptom control, indicating a substantial disease burden. Subsequently, based on the type of the autoantibody and the pathogenesis, we synthesized the published material to date and reached a conclusion regarding the literature related to personalized targeted therapy for MG. Novel agents for AChR MG have shown their efficacy in clinical research, such as complement inhibitors, FcRn receptor antagonists, and B-cell activating factor (BAFF) inhibitors. Rituximab, a representative drug of anti-CD20 therapy, has demonstrated benefits in treatment of MuSK MG patients. Due to the existence of low-affinity antibodies or unidentified antibodies that are inaccessible by existing methods, the treatment for seronegative MG remains complicated; thus, special testing and therapy considerations are necessary. It may be advantageous to initiate the application of novel biologicals at an early stage of the disease. Currently, therapies can also be combined and individualized according to different types of antibodies. With such a wide range of drugs, how to tailor treatment strategies to patients with various conditions and find the most suitable solution for each MG profile are our necessary and urgent aims.

B-cell immune dysregulation with low soluble CD22 levels in refractory seronegative myasthenia gravis

Myasthenia gravis (MG), primarily caused by acetylcholine receptor (AChR) autoantibodies, is a chronic autoimmune disorder causing severe muscle weakness and fatigability. In particular, seronegative MG constitutes 10%-15% of MG cases and presents diagnostic challenges especially in early-onset female patients who often show severe disease and resistance to immunosuppressive therapy. Furthermore, the immunopathology of seronegative MG remains unclear. Thus, in this study, we aimed to elucidate the pathogenic mechanism of seronegative MG using scRNA-seq analysis and plasma proteome analysis; in particular, we investigated the relationship between immune dysregulation status and disease severity in refractory seronegative MG. Employing single-cell RNA-sequencing and plasma proteome analyses, we analyzed peripheral blood samples from 30 women divided into three groups: 10 healthy controls, 10 early-onset AChR-positive MG, and 10 refractory early-onset seronegative MG patients, both before and after intravenous immunoglobulin treatment. The disease severity was evaluated using the MG-Activities of Daily Living (ADL), MG composite (MGC), and revised 15-item MG-Quality of Life (QOL) scales. We observed numerical abnormalities in multiple immune cells, particularly B cells, in patients with refractory seronegative MG, correlating with disease activity. Notably, severe MG cases had fewer regulatory T cells without functional abnormalities. Memory B cells were found to be enriched in peripheral blood cells compared with naïve B cells. Moreover, plasma proteome analysis indicated significantly lower plasma protein levels of soluble CD22, expressed in the lineage of B-cell maturation (including mature B cells and memory B cells), in refractory seronegative MG patients than in healthy donors or patients with AChR-positive MG. Soluble CD22 levels were correlated with disease severity, B-cell frequency, and RNA expression levels of CD22. In summary, this study elucidates the immunopathology of refractory seronegative MG, highlighting immune disorders centered on B cells and diminished soluble CD22 levels. These insights pave the way for novel MG treatment strategies focused on B-cell biology.

Prospective analysis of disability and quality of life in patients with chronic inflammatory demyelinating polyradiculoneuropathy

PURPOSE

Even treated chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) continues to pose a significant burden in patients' everyday functioning and may continuously affect their quality of life (QoL). The aims of our prospective study were to analyze health-related QoL in CIDP patients during a 1-year follow-up period in real-life settings and to compare QoL changes with changes in disability and with patient impression of change.

METHODS

The study comprised 59 patients diagnosed with CIDP. SF-36 questionnaire was applied in order to evaluate patients' QoL. Inflammatory neuropathy cause and treatment (INCAT) disability scale was used to assess patients' functionality. The second question from the SF-36 questionnaire was used as an estimation of the patient impression of change (PIC) after 1 year.

RESULTS

SF-36 scores did not change over time in the group as a whole. According to INCAT disability scores, worsening was registered in 24 (40%) patients and improvement in 8 (14%). Fifteen (25%) patients reported worsening and the same number reported improvement, according to PIC. Concordant results on INCAT and PIC were registered in 49% of patients. Pooled SF-36 scores moderately correlated with pooled INCAT disability scores (rho = - 0.27 to - 0.59, p < 0.01). One-year changes of SF-36 scores did not differ when compared to different INCAT outcomes (worsening, stable, improvement). On the other hand, significant changes of SF-36 scores in different outcome groups according to PIC (worsening, stable, improvement) were noted (p < 0.01).

CONCLUSION

INCAT, PIC, and SF-36 are complementary outcome measures that provide neurologists with useful items of information. We propose complementary use of these scales in CIDP patients in everyday clinical practice in order to detect worsening of the disease and/or of related symptoms on time.