Autoimmune myopathies: autoantibodies, phenotypes and pathogenesis

Area of Science:

• Rheumatology
• Neurology
• Immunology

Background:

• Autoimmune myopathies, including dermatomyositis, polymyositis, and immune-mediated necrotizing myopathies (IMNM), present with proximal muscle weakness and elevated muscle enzymes.
• A significant portion of patients (around 60%) exhibit myositis-specific autoantibodies, each correlating with a distinct clinical presentation.

Purpose of the Study:

• To review the clinical presentations of autoimmune myopathies.
• To detail various myositis-specific autoantibodies and their associated phenotypes.
• To discuss emerging aspects like statin-associated IMNM and the role of interferon signaling and malignancy.

Main Methods:

• Literature review of autoimmune myopathies.
• Analysis of clinical features and muscle biopsy findings.
• Discussion of myositis-specific autoantibodies, including anti-synthetase, dermatomyositis-associated, and IMNM-associated antibodies.

Main Results:

• Autoimmune myopathies share clinical features but have distinct muscle biopsy findings.
• Myositis-specific autoantibodies are present in about 60% of patients and are linked to specific clinical phenotypes.
• A novel form of IMNM associated with statin use and anti-HMGCR autoantibodies has been identified.

Conclusions:

• Understanding the diverse clinical presentations and specific autoantibodies is crucial for diagnosing and managing autoimmune myopathies.
• Further research into interferon signaling, malignancy links, and statin-induced myopathy is warranted.