Yuan YANG1, Geng YIN1, Jingcheng HAO2, Qibing XIE1, Yi LIU1

1Department of Rheumatology and Immunology, West China Hospital of Sichuan University, Chengdu, China
2Department of General, Visceral and Transplantational Surgery, University Hospital of Munich, Campus Grosshardern, Munich, Germany

Keywords: Dermatomyositis; disease activity; interleukin-18; interstitial lung disease; polymyositis


Objectives: This study aims to demonstrate the utilization of serum interleukin-18 (IL-18) level as a biomarker for disease activity and organ damage in patients with dermatomyositis (DM) or polymyositis (PM) using the Myositis Disease Activity Assessment Tool.
Patients and methods: Forty-nine patients (13 males, 36 females) with idiopathic inflammatory myopathies were enrolled in the study. Patients were diagnosed with DM (n=33) or PM (n=16). Twenty age- and sex-matched healthy volunteers (9 males, 11 females) who were determined to be free of autoimmune disease were included as a control group. Disease activity and organ damage were assessed with Myositis Disease Activity Assessment Tool. Serum IL-18 level was measured with enzyme-linked immunosorbent assay and the differences between patient groups were determined.
Results: The mean ages of DM or PM patients were 44 and 45, respectively. Interstitial lung disease (ILD) was found in 24 patients (48.98%), including 18 patients with DM (54.55%) and six patients with PM (37.5%). There was no significant difference of disease duration between DM patients (17.5±22.3 months) and PM patients (14.9±28.7 months). Serum IL-18 level in DM (669.2±528.1 pg/mL) was significantly higher than that in the control group (388.3±139.4 pg/mL, p=0.017), but no significant difference was observed between the PM and control group. IL-18 was significantly higher in DM patients with ILD (890.5±618.8 pg/mL) than in patients without ILD (403.8±84.8 pg/mL, p=0.003). It was significantly elevated in patients with severe disease activity (1001.71±694.2 pg/mL) than in those with moderate (485.3±102.2 pg/mL) or mild disease activity (421.0±270.2 pg/mL) (p=0.039). In DM patients, IL-18 was significantly correlated with global disease activity and disease activity in the skin, lung, and heart.
Conclusion: Serum IL-18 level was higher in patients with DM and this was associated with disease activity and ILD complication. Thus, it can be used as a valuable serological marker for DM disease activity and ILD complication.

Conflict of Interest

The authors declared no conflicts of interest with respect to the authorship and/or publication of this article.

Financial Disclosure

The authors received no financial support for the research and/or authorship of this article.