AUTOANTIBODY PROFILES IN AUTOIMMUNE MYOSITIS

Myositis-specific and myositis-associated autoantibodies

Autoantibodies are a defining feature of autoimmune myositis (AIM) and contribute to the clinical and biological heterogeneity observed across disease subtypes.1,2 Myositis-specific autoantibodies (MSAs) and myositis-associated autoantibodies (MAAs) are linked to distinct patterns of disease presentation, organ involvement, and prognosis.2

Recognition of these autoantibody profiles has transformed understanding of AIM and increasingly informs disease classification and clinical assessment.2,4

Defining MSAs and MAAs1

Autoantibodies identified in AIM are broadly categorised as either myositis-specific autoantibodies (MSAs) or myositis-associated autoantibodies (MAAs).2,3

MSAs are considered relatively specific to AIM and are frequently associated with defined phenotypes.4 In contrast, MAAs may occur in AIM alongside other connective tissue diseases and overlap syndromes.2,4

Most patients with AIM have a single dominant MSA, which may correlate with characteristic patterns of muscle and extramuscular involvement.2,6

Blue and white ceramic vase decorated with anatomical muscle illustrations lying on its side on a wooden floor.

MSAs and clinical phenotype

Distinct MSAs are associated with specific clinical manifestations, patterns of organ involvement, and disease trajectories.2,6–8

 

These associations have contributed to increasing recognition of AIM as a spectrum of autoantibody-defined disease subsets rather than a single clinical entity.2,6,8

Clinical Phenotype

Autoantibodies contribute to distinct muscle and organ
manifestations:5,10–12

Graphic labeled “Skeletal Muscle” showing a diagram of a skeletal muscle beside icons of autoantibodies interacting with muscle cells.
Direct muscle injury

e.g., Anti-HMGCR, Anti-SRP5

Graphic labeled “Lung” showing a diagram of the lungs beside icons of autoantibodies interacting with cells.
Lung endothelial activation

e.g., Anti-Jo-15

Graphic labeled “Skin” showing an inflamed skin cross-section diagram beside icons of autoantibodies interacting with skin cells.
Ulcerative/ vasculopathic skin lesions

e.g., Anti-MDA55

Graphic labeled “GI Tract / Esophagus” showing a simplified diagram of the gastrointestinal tract beside icons of autoantibodies interacting with cells.
Dysphagia/GI involvement

e.g., Anti-FHL15

Graphic labeled “Heart” showing a simplified heart diagram beside icons of autoantibodies interacting with cells.
Cardiac involvement

e.g., Anti-SRP11

Subclinical organ involvement may occur even without overt symptoms: muscle involvement may be asymptomatic, and cardiac involvement in AIM is usually subclinical, with reported prevalence ranging from 4% to 26%; these may be difficult to detect without targeted assessment.12,13

Continue exploring AIM

Learn more about the role of autoantibodies in AIM

How AABs drive disease

Growing evidence suggests that autoantibodies contribute directly AIM pathogenesis.4

Find out more
Diagnosis of AIM

Autoantibody testing has become an increasingly important component of diagnostic evaluation and subtype classification.2,4

Find out more

Abbreviations:
AAB, autoantibody; ADM, amyopathic dermatomyositis; AIM, autoimmune myositis; CCAR-1, cell cycle and apoptosis regulator 1; CN1a, cytosolic 5’-nucleotodase 1A;  EJ, glycyl-tRNA synthetase; FHL1, four-and-a-half LIM domain protein 1; GI, gastrointestinal; HMGCR, 3-hydroxy-3-methylglutaryl-CoA reductase; ILD, interstitial lung disease; KS, asparaginyl-tRNA synthetase; MAA, myositis-associated autoantibody; MDA5, melanoma differentiation-associated gene 5; MSA, myositis-associated autoantibody; NXP2, nuclear matrix protein 2; OJ, isoleucyl-tRNA synthetase; PL7, threonyl-tRNA-synthetase; PL12, alanyl-tRNA synthetase; PM/Scl, polymyositis–scleroderma overlap; SAE, small ubiquitin-like modified activating enzyme; Sp4, transcription factor Sp4; SRP, signal recognition particle; TIF1γ, transcription intermediary factor 1-gamma; U1RNP, U1 small nuclear ribonucleoprotein; ZO, phenylalanyl-tRNA synthetase.

 

References:
1. Groener M and Paik J. Front Immunol. 2025;16:1581323; 2. Wang G and McHugh NJ. Clin Exp Rheumatol. 2025;43(2):364–71; 3. Lundberg IE, et al. Nat Rev Dis Primers. 2021;7(1):87; 4. Halilu F, Christopher-Stine L. Rheumatol Immunol Res. 2022;3(1):1–10; 5. Wu Y, et al. Front Immunol. 2024;15:1439807; 6. Harvey GR, et al. Curr Rheumatol Rep. 2024;27(1):5; 7.  Saygin D, et al. Rheum Dis Clin Rheum North Am. 2025;51(4):563–576; 8. Paik JJ, et al. Rheumatology (Oxford). 2025;64(6):3288–302; 9.  Khoo T, et al. Nat Rev Rheumatol. 2023;19(11):695–712; 10. Diomedi M, et al. Clin Exp Rheumatol. 2026;44(2):167–177; 11. Bandeira M, et al. Front Immunol. 2023;14:1146817; 12. Zhu H, et al. J Inflamm Res. 2025;18:3879–3888; 13. Matsuda N, et al. Acta Radiol Open. 2022;11(2):20584601221075796.