The Role of Interleukin-1 Receptor-Associated Kinases in Vogt-Koyanagi-Harada Disease

PURPOSE To explore whether IRAK1 and IRAK4 are involved in the pathogenesis of Vogt-Koyanagi-Harada (VKH) disease. METHODS Thirty-nine VKH patients and thirty-two healthy controls were included in this study. The mRNA levels of IRAK1 and IRAK4 from active VKH patients, inactive VKH patients, and normal controls in peripheral blood mononuclear cells (PBMCs) were detected using real-time quantitative PCR. CD4(+)T cells were purified from PBMCs obtained from active VKH patients and normal controls. The effect of IRAK1/4 inhibition on CD4(+)T cell proliferation following stimulation with IL-18 or IL-1β was measured using a modified MTT assay. CD4(+)T cell expression of IFN-γ and IL-17 were detected by flow cytometry (FCM) and enzyme-linked immunosorbent assay (ELISA). The effect of IRAK1/4 inhibition on NF-κB, STAT1, and STAT3 activation was detected by FCM. RESULTS The mRNA levels of IRAK1 and IRAK4 were both significantly increased in active VKH patients compared to inactive VKH patients and healthy controls. No difference in the IRAK1 or IRAK4 mRNA level could be detected between inactive patients and healthy controls. After incubation with IRAK1/4 inhibitor, the proliferation of CD4(+)T cells was inhibited both in the active VKH patients and in the healthy controls. IRAK1/4 inhibition was also associated with a decreased expression of IFN-γ and IL-17. Phosphorylation of NF-κB, STAT1, and STAT3 in CD4(+)T from healthy controls was significantly decreased after inhibition of IRAK1/4. CONCLUSIONS High mRNA levels of IRAK1 and IRAK4 correlated with VKH disease activity. IRAK1 and IRAK4 play a role in the activation and proliferation of CD4(+)T cells and the higher expression observed in VKH may contribute to the pathogenesis of this blinding condition.