Association of serum interleukin-18 and other biomarkers with disease severity in adults with atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory disease of the skin for which there are no reliable biomarkers to assess clinical severity. Serum interleukin-18 (IL-18) levels may be associated with AD severity. To identify putative biomarkers associated with clinical severity in adult AD patients, we enrolled 121 adult AD patients (mean age 35.7 years) and 50 healthy controls (mean age 31.7 years). We compared these groups for blood eosinophils and serum levels of IL-18, thymus and activation-regulated chemokine (TARC), total IgE, and lactate dehydrogenase (LDH). We also determined S. aureus enterotoxin B (SEB) specific IgE levels and the SCORingAD (SCORAD) scores for AD patients. For AD patients, stepwise logistic regression was used to estimate odds ratios (OR) for each biomarker for the likelihood of having AD, and multiple linear regression was used to identify biomarkers associated with SCORAD scores. Compared with healthy controls, adult AD patients had higher levels of IL-18, TARC, total IgE, eosinophils, and LDH. TARC levels had the highest OR for AD occurrence, while the OR for IL-18 was insignificant. Also, IL-18 was not related to the presence of SEB-IgE. Notably, IL-18 levels were significantly associated with SCORAD scores, as were TARC, total IgE, and LDH levels. A panel of biomarkers (IL-18, TARC, total IgE, and LDH) may be more useful to accurately assess clinical severity in adult AD patients.