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)-beta [r(s) = 0 center dot 37, 95% confidence interval (CI) 0 center dot 078-0 center dot 62; P = 0 center dot 019] and CXCL10 (r(s) = 0 center dot 32, 95% CI to -0 center dot 004 to 0 center dot 57; P = 0 center dot 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-beta were significantly higher in the patients with acute/subacute interstitial pneumonia (A/SIP) than in the subset without A/SIP (P < 0 center dot 05). IL-6 (r(s) = 0 center dot 54, 95% CI 0 center dot 27-0 center dot 72; P < 0 center dot 001) and IL-18 (r(s) = 0 center dot 46, 95% CI 0 center dot 21-0 center dot 65; P = 0 center dot 003) were significantly correlated with the serum level of anti-melanoma differentiation-associated protein 5 antibody. Conclusions Serum levels of IFN-beta 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-beta were highly correlated with the occurrence of A/SIP. These cytokines may play a role in the pathogenesis of DM and CADM.