Figure 7: Proposed model for the role of IL-9 in promoting a mast cells/ILC2/Th9 fibrotic pathway in CF.
From: A mast cell-ILC2-Th9 pathway promotes lung inflammation in cystic fibrosis
IL-9, produced by IL-33-expanded ILC2, activates MC for IL-2 production leading to the expansion of CD25+ILC2 that promote Th9 cell activation. The resulting increased production of IL-9 further amplifies the inflammatory loop by promoting ILC2 survival and type 2 cytokines production and by activating MC for the production of fibrotic TGF-β. IL-9 ablation or MC inhibition (imatinib) are potential drugable pathways through which inflammation and allergy could be restrained in CF. EC, epithelial cells. αIL-9, IL-9 neutralizing antibody.
