2 research outputs found
Frequency, mutual exclusivity and clinical associations of myositis autoantibodies in a combined European cohort of idiopathic inflammatory myopathy patients
Objectives: To determine prevalence and co-existence of myositis specific autoantibodies (MSAs) and myositis
associated autoantibodies (MAAs) and associated clinical characteristics in a large cohort of idiopathic inflammatory myopathy (IIM) patients.
Methods: Adult patients with confirmed IIM recruited to the EuroMyositis registry (n = 1637) from four centres
were investigated for the presence of MSAs/MAAs by radiolabelled-immunoprecipitation, with confirmation of
anti-MDA5 and anti-NXP2 by ELISA. Clinical associations for each autoantibody were calculated for 1483 patients with a single or no known autoantibody by global linear regression modelling.
Results: MSAs/MAAs were found in 61.5% of patients, with 84.7% of autoantibody positive patients having a
sole specificity, and only three cases (0.2%) having more than one MSA. The most frequently detected autoantibody was anti-Jo-1 (18.7%), with a further 21 specificities each found in 0.2–7.9% of patients.
Autoantibodies to Mi-2, SAE, TIF1, NXP2, MDA5, PMScl and the non-Jo-1 tRNA-synthetases were strongly associated (p < 0.001) with cutaneous involvement. Anti-TIF1 and anti-Mi-2 positive patients had an increased
risk of malignancy (OR 4.67 and 2.50 respectively), and anti-SRP patients had a greater likelihood of cardiac
involvement (OR 4.15). Interstitial lung disease was strongly associated with the anti-tRNA synthetases, antiMDA5, and anti-U1RNP/Sm. Overlap disease was strongly associated with anti-PMScl, anti-Ku, anti-U1RNP/Sm
and anti-Ro60. Absence of MSA/MAA was negatively associated with extra-muscular manifestations.
Conclusions: Myositis autoantibodies are present in the majority of patients with IIM and identify distinct clinical
subsets. Furthermore, MSAs are nearly always mutually exclusive endorsing their credentials as valuable disease
biomarkers