IL-5 enhances human mast cell survival and interferon responses to viral infection

BACKGROUND: Mast cells are important sentinel cells in defense against mucosal infection. Exacerbations of allergic asthma and asthma deaths have been associated with respiratory viral infections. Elevated levels of IL-5 have been associated with the pathogenesis of severe atopic diseases, many of which respond to IL-5 blockade. OBJECTIVE: We sought to examine the impact of IL-5 signaling on mast cells infected with respiratory viruses. METHODS: Cord blood-derived human mast cells were treated with IL-5 or left untreated and infected with human coronavirus OC43, respiratory syncytial virus (RSV), or oncolytic reovirus. Mast cell expression of interferons and of interferon-stimulated genes was evaluated. Total RNA sequencing was performed to determine the impact of IL-5 on the transcriptome of human mast cells, and related functional assays were performed. RESULTS: IL-5-treated mast cells produced significantly more type I and III interferons than did controls not treated with IL-5. Mechanistically, IL-5 treatment led to greater expression of the prosurvival factor B-cell lymphoma 2 (BCL2) and endothelial PAS domain protein 1 (EPAS1) and protected mast cells from apoptosis-induced stress. IL-5 blockade was associated with a decrease in EPAS1 expression in the peripheral blood of asthmatic patients, as shown by transcriptomic data from clinical trials of mepolizumab and benralizumab. CONCLUSIONS: IL-5 signaling selectively promotes interferon responses in mast cells and maintains mast cell populations during mucosal viral infection via a novel IL-5/EPAS1 axis.