Measurement of Cytokines and Chemokines and Association with Clinical Severity of Dermatomyositis and Clinically Amyopathic Dermatomyositis

Background: Dermatomyositis (DM) is an autoimmune disease affecting primarily the skin, muscle and lung. Dysregulations of cytokines and chemokines are commonly found in inflammatory disorders.

Objectives: To investigate the association between serum cytokines and chemokines and clinical severity, especially cutaneous lesions and interstitial lung disease (ILD) in patients with DM and clinically amyopathic DM (CADM).

Methods: Clinical features, laboratory findings and serum of 40 patients with DM or CADM were collected and analysed. Serum cytokines and chemokines were measured by enzyme-linked immunosorbent assay or cytometric bead array. A multiple unpaired t-test was performed to compare cytokines and chemokines in patients with DM and healthy controls. Correlations of serum cytokines and chemokines with disease severity were evaluated by Spearman's rank correlation test.

Results: Serum interferon (IFN)-β [r  = 0·37, 95% confidence interval (CI) 0·078-0·62; P = 0·019] and CXCL10 (r  = 0·32, 95% CI to -0·004 to 0·57; P = 0·045) were significantly correlated with the Cutaneous Dermatomyositis Disease Area and Severity Index activity score in the subset of patients with DM or CADM. Serum levels of interleukin (IL)-6, IL-10, IL-18 and IFN-β were significantly higher in the patients with acute/subacute interstitial pneumonia (A/SIP) than in the subset without A/SIP (P < 0·05). IL-6 (r  = 0·54, 95% CI 0·27-0·72; P < 0·001) and IL-18 (r  = 0·46, 95% CI 0·21-0·65; P = 0·003) were significantly correlated with the serum level of anti-melanoma differentiation-associated protein 5 antibody.

Conclusions: Serum levels of IFN-β and CXCL10 may be useful biomarkers for assessing cutaneous disease activity in patients with DM and CADM. In addition, serum IL-6, IL-10, IL-18 and IFN-β were highly correlated with the occurrence of A/SIP. These cytokines may play a role in the pathogenesis of DM and CADM.