IL-17 family members exert an autocrine pro-inflammatory loop in CF respiratory epithelial cells ex vivo

Lungs of people with Cystic Fibrosis (pwCF) are characterized by chronic inflammation and infection with P. aeruginosa. High levels of IL-17 A and F have been observed in sputum of pwCF and the interleukin-17(IL-17) family (A-to-F) has been suggested to play a key role in CF pulmonary disease.

We measured mRNA levels of IL-17 receptors (IL-17R) by RT-qPCR in CF bronchial epithelial (CFBE) cultured cells upon infection with P. aeruginosa PAO1 strain or clinical exoproducts (EXO) isolated from pwCF. We measured IL-17 mRNA expression by RT-qPCR and the release of cytokines by ELISA and Bioplex from CF primary nasal epithelial (HNE) cultured cells.

Infection of CFBE cells with PAO1 or EXO isolated from 15 pwCF significantly increased mRNA expression of all IL-17R, except IL-17RD. Infection of HNE cells with EXO isolated from the correspondent donor significantly increased the mRNA levels of all the IL-17 cytokines and receptors, except for IL-17D and IL-17RD, and the release of the cytokines IL-17 A, IL-17B, IL-17C, IL-17E and IL-17F. HNE exposed to IL-17 A and F were induced to release pro-inflammatory cytokines (IL-1β, IL-6, TNF-α), neutrophil chemokines (IL-8, G-CSF) and cytokines known to be involved in chloride and bicarbonate secretion, together with mucin upregulation (IL-4, IL-13).

These results highlight a wider expression of IL-17 family member in respiratory epithelial cells, which can play a role as an autocrine inflammatory amplification loop in CF airways. These in-vitro studies using patient-derived cultures underline the relevant role of IL-17 family members in CF pulmonary immune response.