AB0907 HIGH EXPRESSION LEVELS OF TYPE I INTERFERON AND IP-10 IN ANTI-MDA5 ANTIBODY-POSITIVE DERMATOMYOSITIS AND ITS IMPLICATION IN THE PATHOGENESIS

Background Dermatomyositis (DM) patients with anti-melanoma differentiation-associated protein 5 (MDA5) antibodies (Ab) are likely to have rapidly progressing interstitial lung disease and a poor prognosis. Thus, it is important understand the pathogenesis of disease. Objectives The aim this study was identify humoral factor(s) that characterize anti-MDA5 Ab + DM analyze cells produce these factors. Methods Twenty-eight cytokines in serum were screened compared results other collagen vascular diseases. We also performed an immunohistochemical analysis skin rashes (Gottron’s signs) from two patients. Results Serum levels interferon gamma-induced 10 (IP-10, CXCL10), one CXCR3 chemokines, significantly higher than SLE - Moreover, (IFN) α2 After initiation immunosuppressive therapy, IP-10 IFN-α2 decreased rapidly, whereas those IFN-γ CXCL9, another chemokine, did not substantially decrease. Skin samples revealed positive dermis for CD68 antigen, monocyte/macrophage marker. In contrast, they contained few CD8 almost no CD4 cells. stimulated monocytes healthy controls type I II IFNs vitro demonstrated produced culture supernatant dose-dependent manner. Conclusion Our indicate highly ant-MDA5 Abs. IFN high even exceeded SLE. Several reports shown only but induces IP-10. IFN/IP-10 axis may play role DM. released macrophages prompt infiltration themselves, constituting feedback loop inflammation. Further analyses required prove usefulness as activity and/or prognostic marker Reference [1]Kokuzawa A, et al. Clin Exp Rheumatol. 2023 Jan 9. doi: 10.55563/clinexprheumatol/em67zx. Online ahead print. PMID: 36622131 Acknowledgements: NIL. Disclosure Interests Kojiro Sato Grant/research support from: Asahi Kasei Pharma, Boehringer-Ingelheim, Teijin Tanabe-Mitsubishi, Chugai, Ayako Kokuzawa: None declared, Jun Nakamura: Yasuyuki Kamata: declared.