IL-17A mediates pyroptosis via the ERK pathway and contributes to steroid resistance in CRSwNP.

BACKGROUND

Pyroptosis is closely related to inflammation. However, the molecular mechanisms and pathologic contributions of pyroptotic epithelial cell are not yet fully understood.

OBJECTIVE

This study aimed to explore the function and molecular mechanisms of IL-17A on human nasal epithelial cell (hNEC) pyroptosis.

METHODS

The expression of pyroptosis-related biomarkers and IL-17A was assessed in sinonasal mucosa from control individuals, patients with chronic rhinosinusitis without nasal polyps, and patients with chronic rhinosinusitis with nasal polyps (CRSwNP) by using quantitative RT-PCR. Their localization was analyzed via immunohistochemistry and immunofluorescence. The ultrastructural characteristics of IL-17A-induced pyroptosis in hNECs were visualized by using electron microscopy. IL-17A functional assays were performed on hNECs and airway epithelial cell lines. Cytokine levels were quantified via ELISA. The signaling pathways involved in IL-17A-induced pyroptosis were studied via unbiased RNA sequencing and Western blotting.

RESULTS

The expression of IL-17A and the pyroptotic biomarkers NOD-like receptor family, pyrin domain containing 3 (NLRP3), caspase-1, gasdermin D, and IL-1β was increased in nasal mucosa from patients with CRSwNP compared with in those with chronic rhinosinusitis without nasal polyps and the control subjects. IL-17A was positively correlated and colocalized with the pyroptotic biomarkers. IL-17A treatment induced pyroptosis in the hNECs and cell lines analyzed, primarily through the extracellular signal-regulated kinase (ERK)-NLRP3/caspase-1 signaling pathway, and increased IL-1β and IL-18 secretion in hNECs. Moreover, IL-17A-induced pyroptosis contributed to steroid resistance by affecting glucocorticoid receptor-α and glucocorticoid receptor-β expression, and the inhibition of pyroptotic proteins partially abolished IL-17A-induced steroid resistance in hNECs.

CONCLUSION

Elevated IL-17A level promotes pyroptosis in hNECs through the ERK-NLRP3/caspase-1 signaling pathway and contributes to glucocorticoid resistance by affecting glucocorticoid receptor homeostasis in patients with CRSwNP.