ATP, TRP channels and airway neuronal sensitisation

Abstract

Cough is a productive reflex controlled by airway nerves which is respiratory conditions such as chronic obstructive pulmonary disease (COPD), becomes hyperresponsive contributing to the clinical problem of chronic cough. This project was focused on gaining a deeper understanding of the roles of ATP and transient receptor potential (TRP) channels in chronic cough by working with primary bronchial epithelial cells (PBECS) and an in-Vitro human sensory neuronal model differentiated from human dental pulp stem cells termed peripheral neuronal equivalents (PNEs). TRP channels are thought to play a role in the neuronal hyperresponsiveness responsible for chronic cough. Little is know regarding the expression and role of mechanosensitive TRPV2 in the bronchial epithelium. Extracellular ATP levels are increased in the COPD airway. ATP is a potent tussive agent acting via the purinergic P2X3receptor on airway nerves.

In chapter 3 it was hypothesised that TRPV2 is expressed in PBECs and that ATP is released from PBECs following mechanical stimulation; furthermore, it was hypothesised that TRPV2 has a role in ATP release. TRPV2 gene and protein expression was detected in cultured human PBECs and TRPV2 protein was observed in the bronchial epithelium of human lung tissue sections. ATP release was significantly increases in PBECs subjected to shear stress compared with non-stressed controls and the TRPV2 inhibitor tranilast significantly decreased ATP release for shear stress stimulated PBECs.

In chapter 4 the PNE neuronal phenotype and functional expression of P"X£ was validated. In chapter 5 it was hypthesised that ATP evokes hyperresponsiveness of airway neuronal TRP channels via P2X3 activation in PNEs. Acute ATP priming of PNEs resulted in heightened TRPV4 responses at a particular GSK1016790A (TRPV4 agonist) concentration indicating hyperresponsivess of TRPV4 that could be prevented by the P2X3 inhibitor AF-353; however, hypersensitation of the TRPV4 dose response curve with ATP priming was not observed. Sustained a.B-methylene ATP treatment of PNEs resulted in an increase of cytokines associated with neuropathic pain and eosinophilic inflammation.

Thesis embargoed until 31 July 2027.

Date of Award	Jul 2022
Original language	English
Awarding Institution	Queen's University Belfast
Sponsors	BREATH (Border REgions Airway Training Hub)
Supervisor	Fionnuala Lundy (Supervisor), Lorcan McGarvey (Supervisor) & Lorraine Martin (Supervisor)