Serum Interleukin-18 Level is Associated With Disease Activity and Interstitial Lung Disease in Patients With Dermatomyositis.

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.