TSLP Produced by Aspergillus fumigatus-Stimulated DCs Promotes a Th17 Response Through the JAK/STAT Signaling Pathway in Fungal Keratitis

PURPOSE. The purpose of this study was to explore the role of thymic stromal lymphopoietin (TSLP) secreted by Aspergillus fumigatus-stimulated dendritic cells (DCs) during the T helper 17 (Th17) immune response, and further clarify the mechanisms contributing to the Th17 immune response of fungal keratitis (FK). METHODS. A carboxyfluorescein diacetate succinimidyl ester assay, PCR, and flow cytometry were performed to detect Th17 differentiation of CD4(+) T cells; PCR, ELISA, and Western blot were used to detect the expression of TSLP and JAK/STAT-related proteins; Signaling pathways involved in Th17 response was evaluated using RNA sequence; C57BL/6 mice were infected with A. fumigatus and treated with ruxolitinib or BBI608. Slit-lamp examination, fluorescein staining, and clinical scores were used to assess the clinical manifestation. RESULTS. A. fumigatus-infected DCs could drive naive CD4(+) T-cell proliferation and promote the production of Th17 cytokines IL-17A, IL-17F, and IL-22. A. fumigatus stimulation increased the expression of TSLP in DCs. DC-derived TSLP contributed to a Th17-type inflammatory response via the JAK/STAT signaling pathway. TSLP small interfering RNA, TSLPR small interfering RNA, or JAK/STAT inhibitors inhibited the Th17 immune response induced by A. fumigatus-infected DCs. Moreover, TSLP promoted A. fumigatus keratitis disease progression in a mouse model. However, inhibition of the JAK/STAT signaling pathway using a specific inhibitor reversed the development of FK by A. fumigatus infection. CONCLUSIONS. TSLP secreted by A. fumigatus-stimulated DCs played a significant role in the Th17-dominant immune response of FK through its JAK/STAT activation. Our findings may contribute to the elucidation of the molecular mechanisms of FK and to the development of novel therapeutic approaches.