The type I interferon system in idiopathic inflammatory myopathies

Abstract

Polymyositis (PM), dermatomyositis (DM) and inclusion body myositis (IBM) are chronic inflammatory diseases that are characterized by muscle weakness and inflammatory cells in muscle tissue. Autoantibodies are common, some of them are specific for myositis, the most frequent being the anti-Jo-1 antibody which is associated not only with myositis but also with interstitial lung disease and arthritis. A role of type I interferons in disease mechanisms of myositis was first supported by the reported onset of PM and DM during treatment with type I interferon. More recently an interferon signature has been reported in muscle tissue of DM and PM patients both as gene and protein expression, and type I IFN expression in peripheral blood cells seems to correlate with disease activity. Different mechanisms could induce type I interferon in PM and DM like viral infections or endogenous factors as suggested by the observation that sera from myositis patients with anti-Jo-1 antibodies as well as anti-SSA and anti-SSB antibodies have an interferon inducible capacity. Accumulating data indicate a role of the type I interferon in myositis, particularly in juvenile and adult DM and in anti-Jo-1 or anti-SSA positive PM.

Keywords::

• Myopathies
• IFN-I
• MHC
• inflammation
• IFN-signature

Declaration of interest: Grant support. The authors are supported by grants from the Myositis Association, the Swedish Research Council, Stockholm County Council ALF, the Swedish Rheumatism Association, King Gustaf V 80 Year Foundation, Funds at the Karolinska Institutet, the European Union Sixth Framework Programme (project AutoCure; LSH-018661). The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.