Inhibition of ENaC activity by novel peptide trypsin-like inhibitors derived from amphibian skin secretions

E.L. Carroll, L.E.J. Douglas, J.A. Reihill, M. Zhou, T. Chen, L.P. McGarvey, F.T. Lundy, M.A. Hollywood, A. Crilly, J.C. Lockhart, S.L. Martin

Research output: Contribution to journalMeeting Abstract


ENaC is activated by trypsin-like (TL) channel activating proteases
(CAPs), inhibition of which in cystic fibrosis has been shown to increase airways surface liquid and normalise mucociliary clearance (MCC)1. These proteases have potential to be therapeutic targets in other chronic airways diseases. This study investigated the ability of natural peptide TL inhibitors, derived from amphibian skin secretions, to inactivate ENaC via CAP inhibition.

Initial screening of the frog peptides was conducted using FRT cells stably transfected with ENaC and changes in fluorescence intensity (FLIPR) utilised to measure ENaC activity. Second round testing was performed using primary differentiated human airway epithelial cells (hAECs) by measurement of IEQ (equivalent short-circuit current) (TECC-24; EP Devices).

FLIPR revealed that all of the frog peptides significantly inhibited
ENaC, particularly QUB-1916 which elicited almost immediate,
complete channel inhibition. Different trends were observed when
the peptides were tested on hAECs using short-circuit current,
with other peptides demonstrating superior ENaC inhibition compared to QUB-1916. Initial profiling indicates a differential protease expression pattern between cell types which may underlie this discrepancy.

These findings highlight the importance of direct testing of channel activity using hAECs. Potential lead compounds are currently being evaluated for efficacy in airway hydration and MCC
Original languageEnglish
Pages (from-to)S250-S251
Number of pages2
JournalIrish Journal of Medical Science
Issue numberSupplement 8
Publication statusPublished - Aug 2018


  • COPD
  • ENaC
  • interreg va
  • trypsin


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  • Asthma/COPD Project of the Year, 19th Northern Ireland Healthcare Awards 2018

    Martin, Lorraine (Recipient), McGarvey, Lorcan (Recipient), Lundy, Fionnuala (Recipient), Litherland, Gary (Recipient), Lockhart, John (Recipient), Crilly, Anne (Recipient), Goodyear, Carl (Recipient), Thornbury, Keith (Recipient), Hollywood, Mark (Recipient), Sergeant, Gerard (Recipient) & McHale, Noel (Recipient), 22 Feb 2018

    Prize: National/international honour

  • Northern Ireland Healthcare Awards

    Lockhart, John (Recipient), 22 Feb 2018

    Prize: Prize (including medals and awards)

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