Ultrasensitive Interferons quantification in idiopathic inflammatory myopathies serve as biomarkers of activity in dermatomyositis and anti-synthetase syndrome

Abstract Objectives Inflammatory idiopathic myopathies (IIM) are a heterogeneous group of disorders, ranging from a muscle-specific autoimmune disease to a systemic one that are difficult to assess. Recent insights into IIM pathogenesis highlighted the role of interferon (IFN) in the pathophysiology. The aim of this study was to test if IFN serum levels can a use as a biomarker of disease activity in IIM. Methods IFN type I and II were measured using an ultrasensitive detection technology and assess the potential of IFN. Results One hundred and fifty-two patients (dermatomyositis (DM); n=50, anti-synthetase syndrome (ASyS); n=46, immune-mediated necrotizing myopathy (IMNM); n=32, inclusion body myositis (IBM); n=24) and 33 age-matched healthy donors were included. IFN-α levels were higher only in DM (0.07 pg/ml [0.03-0.23], p<0.005) and ASyS groups (0.07 [0.02-0.16], p<0.05) compared with controls (0.02 [0.01-0.05]). IFN-β was increased only in DM and IFN-γ among all IIM. IFN-α levels were correlated with disease activity in DM (r=0.76, p<0.0001). The predictive accuracy of IFN-α level to discriminate active and non-active disease was excellent as reflected by an area under the ROC-curve of 0.88. Using an IFN-α level cut-off above 0.11 pg/ml, the sensitivity was 75% and the specificity was 96% in DM patient. IFN-α and IFN-γ were correlated with disease activity in ASyS groups (r=0.55 and r=0.46 p