High-plex spatial protein profiling of skeletal muscle biopsies in inflammatory myopathies using the MACSima™ imaging platform: A pilot study.

Inflammatory myopathies represent a heterogeneous group of autoimmune disorders affecting skeletal muscle, with distinct pathological features. While muscle biopsy remains a key diagnostic tool, conventional immunohistochemical approaches are limited in both number of available markers and spatial resolution. To explore the feasibility and potential of the MACSima™ Imaging Platform for high-dimensional, spatially resolved analysis of skeletal muscle tissue in inflammatory myopathies, we applied a panel of antibodies targeting immune cells, extracellular matrix components, blood vessels, and lymphatic markers to skeletal muscle cryosections from patients with different inflammatory myopathies and age-matched controls. Using the MACSima™ platform, we performed iterative immunofluorescence staining and imaging cycles to generate multiplexed protein maps. The platform enabled robust signal acquisition and preserved tissue morphology throughout all cycles. Preliminary spatial analysis revealed distinct immune cell infiltration patterns, ECM remodeling signatures, and vascular changes across disease subtypes. This pilot study demonstrates the feasibility of applying high-dimensional multiplex imaging to skeletal muscle using the MACSima™ system. Our results represent a first partial spatial profiling of muscle pathology in autoimmune myopathies using an innovative methodological approach.