Background

The differentiation of airway epithelial cells (AEC) relies on Hedgehog (HH) signalling. Epithelial remodelling is associated with HH inhibition in COPD. The core elements of HH signalling were investigated in the context of COPD but the mechanisms were not deciphered.

Objectives

We aim for the identification of HH molecular targets regulating AEC differentiation and their potential alteration in COPD.

Methods

RNA sequencing was performed on air-liquid cultured AEC isolated from bronchial brushes and treated or not with HH pathway inhibitor (AB5E1). The most significant differentially expressed genes were selected by bioinformatics. Gene expressions were also investigated by single-cell RNAseq analysis. Immunofluorescent stainings were executed to examine protein localization and expression on bronchial epithelia of non-COPD and COPD patients.

Results

Twenty-three differentially expressed genes more than 2-fold were found in AEC treated with HH inhibitor. POU5F1 (OCT3/4) and FER1L5 gene expression increased by 2.1 and 2.7-fold (p<0.05) whereas CXCL5 transcripts decreased by 2.8-fold (p<0.05). Their proteic abundance was different in the bronchial epithelial cells: FER1L5 preferentially localised in submucosal glands, and CXCL5 preferentially localised in goblet cells. They were more abundant in COPD bronchial tissues by respectively 17.3+/-4.6% (p<0.01) and 59.3+/-15.8% (p<0.01).

Conclusion

This study identified novel regulators of the HH pathway that may be involved in COPD epithelial remodelling. Future investigations will determine their role and the impact of their modulation during AEC differentiation to unveil additional biomarkers of interest in the context of COPD.