Objective: Idiopathic inflammatory myopathies (IIMs) are a group of heterogeneous, systemic autoimmune diseases characterized by specific clinical features and, frequently, skeletal muscle inflammation. Specific subtypes of IIMs can be characterized by myositis-specific autoantibodies and are associated with distinct clinical phenotypes. Here, we focus on anti-melanoma differentiation-associated protein 5 (MDA5)-positive myositis and anti-signal recognition particle (SRP)-positive myositis, both of which exhibit seasonality but lack known environmental triggers.
Methods: We employed Phage ImmunoPrecipitation Sequencing to profile serum antibodies against the human proteome, the human virome, and a comprehensive enterovirus library. We analyzed sera from 57 patients with anti-MDA5 autoantibodies and 57 patients with anti-SRP autoantibodies, as well as 57 healthy controls. All groups were matched for age, sex, and race.
Results: Our autoantibody profiling results define specific immunogenic regions within the MDA5 and SRP autoantigens. We also discovered that in MDA5 sera, versus SRP sera, there was an elevated antibody response to the viral capsid protein 1 (VP1) of enterovirus B, which was accompanied by a decreased antibody response to rhinovirus A.
Conclusion: Considering the role of MDA5 as a sensor of picornaviral infections and a mediator of inflammatory signaling, our data suggest a novel etiologic link between enterovirus infection and anti-MDA5 dermatomyositis.
© 2024 The Author(s). ACR Open Rheumatology published by Wiley Periodicals LLC on behalf of American College of Rheumatology.