Increased serum level of interleukin-33 in Vogt-Koyanagi-Harada correlates with disease activity.

OBJECTIVES To measure the serum level of IL-33 in patients with Vogt-Koyanagi-Harada disease (VKH) and Behcet's uveitis (BU) in the Chinese Han population and investigate its associations with disease activity and clinical parameters. METHODS Serum was collected from 41 VKH patients (16 active and 25 inactive patients), 60 BU patients (24 active and 36 inactive patients), and 36 healthy controls. The serum level of IL-33 was measured using the enzyme-linked immunosorbent assay (ELISA) method. Demographic features, clinical manifestations, and intraocular inflammation activity scores (anterior chamber cells score, anterior chamber flare score, and vitreal haze score) were recorded. RESULTS The serum level of IL-33 significantly increased in all VKH patients, active VKH patients, and inactive VKH patients, as compared to healthy controls (p < 0.001, p < 0.001, and p = 0.002, respectively), and was higher in the active VKH than in the inactive VKH patients (p = 0.049). The serum level of IL-33 positively correlated with the anterior chamber cells score, vitreal haze score, and the annualized number of relapses in VKH patients (Rho = 0.359, p = 0.021; Rho = 0.344, p = 0.028; Rho = 0.537, p < 0.001, respectively). Serum IL-33 level was significantly associated with the annualized number of relapses in patients with BU (Rho = 0.361, p = 0.005). CONCLUSION Serum IL-33 level is significantly increased in VKH patients in the Chinese Han population. IL-33 level is in positive correlation with the activity and relapses of VKH. Increased IL-33 might contribute to the pathogenesis of VKH and serve as a potential biomarker for VKH disease.