A multi-dimensional phenotyping framework reveals coordinated neuromuscular, immune, and imaging-derived phenotypes in experimental autoimmune myasthenia gravis.

BACKGROUND

Experimental autoimmune myasthenia gravis (EAMG) is widely used to investigate the pathogenesis and treatment of myasthenia gravis. However, current evaluation strategies rely predominantly on isolated endpoints and do not fully capture the relationship between neuromuscular dysfunction, immune alterations, and whole-animal phenotypic changes.

METHODS

We established EAMG in C57BL/6J mice and implemented a two-tier analytical framework consisting of full-cohort core phenotyping and phenotype-enriched imaging analyses. Core assessments included longitudinal body weight, clinical scoring, electrophysiological testing, behavioral assays, serum anti-AChR levels, and peripheral blood Th17/Treg ratio. In a selectively assessed imaging subset, cardiac ultrasound, micro-CT, and 18F-FDG PET/CT were performed to explore selected imaging-derived cardiac, metabolic, and postural phenotypes. Associations between phenotypic readouts and disease severity were assessed using correlation analyses.

RESULTS

EAMG mice developed consistent neuromuscular and immunological abnormalities, including significant electrophysiological decrement, reduced grip strength and endurance, elevated anti-AChR levels, and increased Th17/Treg ratio. Among these readouts, electrophysiological impairment showed the strongest association with disease severity (rho = -0.79, P < 0.001), whereas behavioral and immunological measures demonstrated limited stratification capacity within the EAMG group. In the phenotype-enriched imaging subset, EAMG mice showed reduced cardiac ejection fraction, reduced heart rate, decreased iliopsoas FDG uptake, and reduced sagittal spinal angle. Iliopsoas FDG uptake was negatively correlated with disease severity within this subset (rho = -0.89, P = 0.041).

CONCLUSIONS

EAMG was associated with coordinated electrophysiological, functional, and immunological abnormalities in the full cohort. Exploratory imaging analyses in a phenotype-enriched subset further identified selected cardiac, metabolic, and postural phenotypes in animals with overt disease manifestations. This multi-dimensional framework may support more comprehensive assessment of disease progression in preclinical myasthenia gravis studies, while the imaging-derived findings require validation in unselected cohorts.