Objective:

To undertake a comprehensive and comparative analysis of sera from patients with myasthenia gravis (MG) using advanced proteomic techniques for biomarker discovery.

Background:

Generalized MG can cause significant muscle weakness so early diagnosis is important for institution of effective treatment. Serum antibodies (against acetylcholine receptor (AchR), muscle specific kinase (MuSK) and lipoprotein 4) can be absent in ~15% patients. Moreover, these antibodies have limited prognostic value. More robust and biomarkers can be helpful for early diagnosis and for further clinical characterization of the disease. We had previously identified fibrinogen as a candidate serological biomarker for MG. More advanced and high-throughput novel methods can provide a more comprehensive analysis of the proteome as compared to traditional techniques.

Design/Methods:

We undertook next-generation proteomics to compare the proteome profiles of sera from patients with MG to sera from patients with diverse group of diseases (multiple sclerosis MS, rheumatoid arthritis RA, stroke) and controls.

Results:

Sera from MG patients revealed distinct alterations within the coagulation cascade, including persistent residual fibrinogen. These findings were validated via enzyme linked immunosorbent assay (ELISA) across a diverse MG cohort, including anti-AchR and anti-MuSK antibody positive MG, both treated and treatment-naive individuals. To assess pre-analytical variability, we conducted a time-course study evaluating sample processing intervals from 45 minutes to 4 hours, revealing significant fluctuations in fibrinogen levels with delayed handling, highlighting the importance of standardized protocols in biomarker quantification. Secondly, proteomic profiling uncovered pronounced dysregulation of the complement cascade uniquely associated with MG, a signature distinct from other autoimmune conditions (i.e. RA, MS), stroke, and controls.

Conclusions:

Sera from all serotypes of MG exhibit elevated fibrinogen levels consistent with our earlier observations. Our findings provide a comprehensive serological proteomic landscape of MG that will advance mechanistic insights and pave way for more sensitive, reproducible, and clinically useful biomarkers.