Single‐Cell Transcriptomic Analysis on Multi‐Subtypes of Idiopathic Inflammatory Myopathy Reveals Pathologic Hallmarks Associated With Stromal Stem and Immune Cells in Damaged Skeletal Muscles
Authors' conclusion
The study provides valuable single-cell transcriptomic resources for describing pathologic cell atlas across IIM subtypes. We highlighted not only common changes in IIM (ie, expression of MEF2C and IFN-I) but also outlined distinct characteristics among the four subtypes of IIM.
Study context
- Population
- Affected skeletal muscle and PBMCs from patients with four idiopathic inflammatory myopathies (IIM) subtypes and healthy controls
- Comparison
- Four IIM subtypes vs healthy controls
- Healthy controlsn = 5reference
- Anti-Mi2 DMn = 3-5
- Anti-MDA5 DMn = 3-5
- Anti-NXP2 DMn = 3-5
- Anti-HMGCR IMNMn = 3-5
Methodological detailssingle-cell RNA sequencing, immunohistochemistry and cell culture validation
- Single-cell RNA sequencing
- Immunohistochemistry and cell culture validation
Main finding
As reported in the abstract
- Reduction in type IIa/IIx myofiber cells across more inflammatory IIM subtypes (among 12 cell types)
- IFN-I signaling selectively hyperactivated in DM, not obvious in IMNM
- MEF2C expression appears reduced, associated with delayed myofiber genesis and altered muscle function
- MuSCs1 and Myoblasts1 clusters associated with disrupted muscle regeneration, with IFN-I indicated in aberrant differentiation
- M1-like macrophages suggested to interact with muscle cells via TNF signaling, leading to muscle inflammation
- CXCL10+ fibroblasts likely recruit M1-like macrophages via CCL19-CCR7/CCRL2 axis
- Peripheral CD14+ monocytes show high IFN activity and polarize to M1-like phenotype after infiltrating muscle
Original publication
Single‐Cell Transcriptomic Analysis on Multi‐Subtypes of Idiopathic Inflammatory Myopathy Reveals Pathologic Hallmarks Associated With Stromal Stem and Immune Cells in Damaged Skeletal Muscles. Arthritis Rheumatol. Published 20 April 2026. doi:10.
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