LAUSR

Background: By autoantibodies, myositis is recently classified into subgroups with distinctive clinical features. Cytokines play critical roles in the development of the clinical features. However, it is not fully unknown whether myositis subgroups defined by autoantibodies have unique cytokine profiles. Objectives: To clarify the relationship between cytokine profiles and autoantibodies in myositis. Methods: Subjects were myositis patients who admitted Dokkyo Medical University and whose serum before starting therapy were available. Serum cytokine levels (IL-1a, 1b, 2, 4,5, 6, 10,12, 13,15,17, 23,IFN-g, TNF-a, IFN-a, b,IP-10 and MCP-1) in sera from the patients and controls were measured using Q-Plex™ Multiplex Arrays. Demographic and clinical data were obtained by reviewing medical record retrospectively. Results: Subjects were 45 myositis patients with male/female; 22/23 and 59.4 years of mean age. Amyopathic dermatomyositis (ADM), classical DM and polymyositis (PM) were 21, 11 and12 cases, respectively. Autoantibodies were anti-MDA5+ in 21, anti-ARS+ in18 and anti-TIF1g+ in 5 cases. ILD and malignancy was complicated in 39 and 5 cases, respectively. Serum cytokine levels were measured. As shown in Fig.1, IP-10 levels were increased in all types of myositis patients, but not in controls. In ant-MDA5 Ab + myositis, IL-6, IL-10, IL-15, TNF-a, IFN-a and MCP-1 levels were increased. In anti-ARS Ab+ cases, IFN-b levels were elevated as well as TNF-a and MCP-1. Through the correlation analysis between cytokine levels, cytokine groups were identified (Fig.2). In anti-MDA5 Ab+ cases, 2 cytokine groups were identified; one includes IFN-a, IL-15, TNF-a and IL-10, and the other involved IL-6, MCP-1. Both groups connected with IP-10. In In anti-ARS Ab+ cases, 2 groups were found; one included TNF-a, MCP-1and IP-10, and the other had IFN-b as a sole component.Figure 1 Serum cytokine levels in myositisFigure 2 Cytokine networks in a-ARS ab+ and a-MDA5 ab+ myositis Conclusion: Cytokine profiles differ among subgroups in myositis. In anti-DDA5+ myositis, IL-15 and IFN-a with strong correlation and IL-6 were characteristic cytokines, while IFN-b was a unique one in anti-ARS+ myositis Disclosure of Interests: None declared