Myositis is a general term for inflammation or swelling of the muscles. Injury, medicines, infection, or an immune disorder can lead to myositis. It is e.g. a documented side effect of the lipid-lowering drugs statins and fibrates. Types of myositis include:myositis ossificans, dermatomyositis, juvenile dermatomyositis, polymyositis, inclusion body myositis and pyomyositis.
Researchers have developd a reproducible experimental autoimmune myositis model of polymyositis, mice were immunized once a week for 3 weeks with 1 mg of partially purified myosin emulsified in complete Freund's adjuvant. All mice injected with myosin and complete Freund's adjuvant developed myositis. The autoimmune myositis is a reproducible, transferable disease in mice, both aggravated by Treg depletion and improved by polyclonal Treg injection.