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

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.

We sought to examine the impact of IL-5 signaling on mast cells infected with respiratory viruses.

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.

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.

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.