Abstract
Background: Pseudomonas aeruginosa (PA) is a key pathogenic factor in several pulmonary conditions including COPD, CF and pneumonia. PA secretes a number of virulence factors including exotoxin A (EXA), a highly toxic product activated by the action of the pro-protein convertase furin, which contributes to mortality in patients and animal models. Within our laboratory we have recently developed a novel small molecule-based inhibitor of furin potentially relevant in this context.
Hypothesis: QUB-TL1 prevents EXA-induced airway epithelial cell (AEC) cytotoxicity as a consequence of furin inactivation.
Methods: Recombinant furin activity was performed by monitoring cleavage of a fluorogenic substrate (pERTKR-NHMec). Turnover of the same substrate was monitored upon addition to the apical surface of differentiated AECs to assess surface furin activity in the presence or absence of QUB-TL1. Cytotoxicity was assessed using a commercial LDH assay kit.
Results: QUB-TL1 inhibits recombinant and endogenous furin activity (detected at the apical surface of normal and CF AECs). Moreover EXA-induced epithelial cell cytotoxicity is significantly reduced (>80%) in the presence of QUB-TL1. Further studies demonstrated QUB-TL1 itself was non-toxic and cell impermeable thus affording a sustained duration of action at the airways surface whilst limiting off-target effects.
Conclusions: QUB-TL1 represents a novel cell impermeable inhibitor of furin that abrogates EXA-induced cytotoxicity in AECs thus may be of therapeutic value with regards PA lung infections.
- © 2014 ERS