Ubiquitination is a post-translational process critical to the regulation of protein localisation, activity and degradation. Deubiquitinating enzymes (DUBs) can however, reverse the fate of proteins by removing ubiquitin. Dysregulation of DUB activity is implicated in numerous pathologies to include cancer, autoimmune, neurodegenerative and chronic inflammatory diseases.

Chronic inflammation is associated with disease progression in chronic obstructive pulmonary disease (COPD) therefore, the aim of this study was to investigate individual DUBs as potential novel therapeutic targets.

A DUB knock out (KO) screen of 96 DUBs in fully differentiated human COPD primary bronchial epithelial cells (PBECs) was conducted using CRISPR/Cas9 technology and cell conditioned media analysed for cytokines by ELISA. Inhibitor studies in the presence of stimulants (ATP and lipopolysaccharide) were conducted in both COPD PBECs and differentiated THP-1 cells to ascertain the role of DUBs in inflammation.

The DUB KO screen identified several DUBs with an ability to reduce inflammatory signalling in PBECs. Previous studies have suggested a relationship between DUBs and NLRP3 inflammasome activation. Selective DUB KO reduced IL-8, GM-CSF and IL-6 signalling. Selective inhibition also showed an ability to reduce IL-8 signalling with a concomitant increase in cytosolic pro-caspase-1, which may reflect a reduction in active caspase-1. Inhibition of DUBs in THP-1 cells reduced caspase-1 activity.

DUBs offer significant opportunity in COPD as putative therapeutic targets for novel drug discovery. Further investigation is required to characterise the role of individual DUBs in inflammatory pathways in COPD to include activation of the NLRP3 inflammasome.