Figure legends.
Figure 1. Innate lymphoid cells. A. ILC can be divided into three subsets ILC1, ILC2 and ILC3. ILC1 express the transcription factor T-bet and, in response to IL-12, IL-15, and IL-18, produce IFN-γ and TNF-α. ILC2 express the transcription factor GATA-3 and, in response to the alarmins TSLP, IL-25, HMGB1 and IL-33, secrete IL-4, IL-5 and IL-13. ILC3 express the transcription factor RORγt and in response to IL-23 and IL-1β, release IL-17 and IL-22. B. ILC2 can transdifferentiate into ILC1 or ILC3 in response to IL-1β IL-12 and TGF-β and these trans differentiations can be reversed by Th2 cytokines, as IL-4. C. Toll-like-receptor-2 ligands can promote the production of the Th2 cytokines IL-5 and IL-13 by ILC3 cells, which suggests that these cells might be able to differentiate into ILC2 cells.
Figure 2. Following RSV infection, through the release alarmins BECs stimulate ILC2 to release IL-4, IL-5, and IL-13. IL-4 drives Th2 cell differentiation and promotes B cell antibody class switch to IgE. IL-5 is involved in eosinophils recruitment and in their survival enhancement. IL-13 increases goblet cell mucin and airway responsiveness.
Figure 3. Changes in gut microbiota community composition following RSV infection and allergen sensitization in mice. A. RSV infection was associated with significant increase in the relative abundance of Bacteroidetes  and a corresponding decrease in Firmicutes . B. In ovalbumin (OVA) sensitized mice, lower abundance of both Bacteroidetes and Firmicutes infection was detected. C. in mice, previously sensitized to OVA, RSV infection was associated with higher abundance of both Bacteroidetes andFirmicutes . Bacteroidetes were most significantly associated with IL-4, IL-5, IL-13, IL-25, and IL-33 production andFirmicutes with IL-33.