Serum levels of interleukin-33 in alopecia areata: relation to disease severity and chronicity

Background Alopecia areata (AA) is an autoimmune disease of the hair follicles, in which both innate and adaptive immunity are involved. Several factors have been linked to its etiopathogenesis, including genetic predisposition, autoimmunity, proinflammatory cytokines, and other triggering factors. Objective To measure serum interleukin-33 (IL-33) in AA patients and study its relation to different disease-related and patient-related factors. Patients and methods In total, 40 AA patients and 40 controls were enrolled. Clinical disease severity was determined and severity of alopecia tool score was calculated. Disease activity was evaluated. Serum IL-33 was measured using enzyme-linked immunosorbent assay and investigated in relation to the different studied variables. Results Significantly higher levels of IL-33 were detected in sera of patients compared with controls (P<0.001). IL-33 showed a significant positive correlation with clinical disease severity (P=0.044), severity of alopecia tool score (P=0.004), and disease duration (P=0.023). IL-33 was significantly higher in patients with chronic disease compared with those with acute disease (P=0.037). No significant relation was detected between disease activity and IL-33 (P=0.963). Receiver-operating characteristic analysis revealed a cut-off value of 14.02 pg/ml for IL-33 to be diagnostic of AA. Conclusion The elevated IL-33 in patients, in addition to the relation of IL-33 with disease severity and chronicity, could point to its possible role in the pathogenesis of AA and to its potential value as a diagnostic biomarker and as a therapeutic target.