Allergen protease-induced Gsdmd p40 controls IL-33 secretion

Abstract Interleukin (IL)-33, an epithelial cell-derived cytokine that responds rapidly to environmental insult, has a critical role in initiating airway inflammation, such as that in asthma. However, the molecular mechanism underlying IL-33 secretion following allergen exposure is not clear. Here, we demonstrated that Gasdermin D (Gsdmd) functions as a conduit for IL-33 secretion following allergen protease exposure. Gsdmd was rapidly cleaved into a functional neo-form, the N-terminal p40 fragment (p40 NT-Gsdmd), in the murine airway epithelium when cells were exposed to allergen proteases from fungi, house dust mites (HDMs), or bacteria. This cleavage event that produces the p40 Gsdmd fragment was independent of inflammatory caspases-1/11, as it could not be inhibited by caspase-1 and caspase-11 deficiency in murine cells. The functional p40 NT-Gsdmd fragment directly contributed to the secretion of both the nuclear full-length form and cytosolic mature form of IL-33. Both Gsdmd deficiency and blockade of the generation of p40 by amino acid mutation or deletion of residues 308–313 (ELRQQ) in the Gsdmd sequence could efficiently prevent IL-33 release in airway epithelial cells. In mice, Gsdmd deficiency prevented IL-33 release and hindered the activation of group 2 innate lymphoid cells (ILC2s), thus alleviating airway inflammation and lung tissue damage after stimulation with HDMs or papain. Our findings uncovered a mechanism of Gsdmd-mediated IL-33 release under allergen exposure and offer insight into Gsdmd cleavage prevention as a potential approach to reduce allergic airway inflammation.