The Muscle Disease Section focuses its research on myositis, a rare family of autoimmune diseases in which the body's immune system attacks healthy muscle tissue, causing inflammation, weakness, fatigue, and pain in skeletal muscles. Problems that affect the skin, lungs, and joints often accompany myositis. 

Research Focus:

• Dermatomyositis, which can include a skin rash.
• The anti-synthetase syndrome, which can include a rash, lung disease, and arthritis.
• Inclusion body myositis, which typically affects the muscles of older adults. 
• Immune-mediated necrotizing myopathy, which can cause especially severe weakness in children and adults alike.

Lab Goals: 

• Define the different subtypes of autoimmune muscle disease based on muscle histology, autoantibodies, and other biomarkers.
• Describe the role of myositis autoantibodies in the pathogenesis of myositis. 
• Develop animal models of myositis that are relevant to human diseases.
• Understand how environmental exposures, including medications such as statins and cancer immunotherapies, can trigger autoimmune muscle disease. 
• Use novel therapeutic strategies to treat myositis patients at the NIH Clinical Center.

In 2007, while on the faculty at Johns Hopkins, Dr. Mammen co-founded the Johns Hopkins Myositis Center. This group discovered a form of immune-mediated necrotizing myopathy triggered by statins, a medication used to lower cholesterol concentrations (Arthritis Rheum 63:713–721, 2011). This disease occurs in approximately 1 in 50,000 Black and white Americans exposed to statins. However, working with colleagues in New Mexico, they found that around 1 in 300 members of the Navajo Nation may develop this form of myositis if exposed to statins (Arthritis Rheum 2022; DOI:10.1002/art.42126; online ahead of print). Dr. Mammen's research continues to investigate why some people can safely use statins while others have an increased risk of developing myositis and should avoid this cholesterol-lowering medication.