POS1312 ANALYSIS OF INTERFERON TYPE I SIGNATURE IN JUVENILE DERMATOMYOSITIS

Background the crucial role of hyperactivation IFN I signaling pathway has been proved in pathogenesis dermatomyositis. genes and chemokines activity vary according to subtype inflammatory myopathies. type 1 signature could be measured using different blood, skin muscle tissue [1]. Objectives evaluate IFN-score children with dermatomyositis compare disease Methods 15 patients (5 boys 10 girls) were enrolled study. Clinical laboratory parameters, (CMAS-childhood myositis assessment tool, aCAT- abbreviated cutaneous tool) treatment assessed. Patients compared accordingly elevation. I-score was assessed by RT-PCR quantitation 5 I-regulated transcripts (IFI44L, IFI44, IFIT3, LY6E, MXA1); median relative expression ≥ 2 considered as a cut-off. evaluated dynamics 9 patients. Results age 6.2 (3.6; 7.6) years. Skin involvement all patients, arthritis (33%) calcinosis 3 (20%), lipodystrophy (13%) lung (33%), (60%) had positive myositis-related antibodies. Ten (67%) an active disease, while elevated IFN-signature detected 12 (80%) Cumulative its’ five components higher inactive (13.6 vs 1.4, p=0.006). increased lower CMAS score aCAT normal levels I-score. IFN-I correlated aCAT, involvement. Conclusion may biomarker juvenile predominantly process. References [1]Rigolet M, Hou C, Baba Amer Y, Aouizerate J, Periou B, Gherardi RK et al. Distinct interferon signatures stratify dysimmune RMD Open. 2019 Feb 26;5(1):e000811. doi: 10.1136/rmdopen-2018-000811. PMID: 30886734; PMCID: PMC6397431. Acknowledgements This work supported RSF grant № 20-45-01005 Disclosure Interests None declared