ABSTRACT
Introduction: A working hypothesis is that juvenile dermatomyositis (JDM) is a type 1 interferon driven inflammatory response, triggered by one or more environmental stimuli, such as infection. Objectives: We aimed to test the hypothesis that SARS-CoV-2 infection could promote JDM onset or relapse. Methods: We studied SARS-CoV-2 infection history in all JDM patients seen in our center for disease onset (n=6) or relapse (n=4) since the start of the pandemic. IgG and IgM directed against whole spike protein, spike Receptor Binding Domain (RBD), spike S2 subunit, nucleocapsid protein (NP) and Membrane glycoprotein (ME) were measure in the plasma by multiplex bead-based assay at diagnosis. IFNα2 level in the plasma was measure by digital ELISA. Results: Out of the 10 patients we identified concomitant infection by SARS-CoV-2 with disease onset in one patient, and concomitant infection by SARS-CoV-2 with disease relapse after 8 years out of treatment in one other. IFNa2 dosages in the plasma of these two patients revealed abnormally elevated concentrations (73476 fg/ml and 4612fg/ml respectively, median active JDM: 491fg/ml). Conclusion: Our results strongly suggest that SARS-CoV-2 infection could trigger the development of JDM, possibly through induction of IFNα.