TY - JOUR T1 - Distinct interferon signatures stratify inflammatory and dysimmune myopathies JF - RMD Open JO - RMD Open DO - 10.1136/rmdopen-2018-000811 VL - 5 IS - 1 SP - e000811 AU - Muriel Rigolet AU - Cyrielle Hou AU - Yasmine Baba Amer AU - Jessie Aouizerate AU - Baptiste Periou AU - Romain K Gherardi AU - Peggy Lafuste AU - François Jérôme Authier Y1 - 2019/02/01 UR - http://rmdopen.bmj.com/content/5/1/e000811.abstract N2 - Objective The role of interferons (IFN) in the pathophysiology of primary inflammatory and dysimmune myopathies (IDM) is increasingly investigated, notably because specific neutralisation approaches may constitute promising therapeutic tracks. In present work we analysed the muscular expression of specific IFNα/β and IFNγ-stimulated genes in patients with various types of IDM.Methods 39 patients with IDM with inclusion body myositis (IBM, n=9), dermatomyositis (DM, n=10), necrotising autoimmune myopathies (NAM, n=10) and antisynthetase myositis (ASM, n=10), and 10 controls were included. Quantification of expression levels of IFNγ, ISG15, an IFNα/β-inducible gene and of six IFNγ-inducible genes (GBP2, HLA-DOB, HLA-DPB, CIITA, HLA-DRB and HLA-DMB) was performed on muscle biopsy samples.Results DM usually associated with strong type I IFNα/β signature, IBM and ASM with prominent type II IFNγ signature and NAM with neither type I nor type II IFN signature. Immunofluorescence study in ASM and IBM showed myofibre expression of major histocompatibility class 2 (MHC-2) and CIITA, confirming the induction of the IFNγ pathway. Furthermore, MHC-2-positive myofibres were observed in close proximity to CD8+ T cells which produce high levels of IFNγ.Conclusion Distinct IFN signatures allow a more distinct segregation of IDMs and myofibre MHC-2 expression is a reliable biomarker of type II IFN signature. ER -