Chronic cough is a common troublesome symptom which has a global prevalence of approximately 10%, but with wide variations across continents. Patients with refractory and unexplained chronic cough (RCC/UCC) often exhibit dysregulated vagal pathways, necessitating a neuronal biomarker for targeted treatment. ATP, involved in the ATP/P2X3 pathway, may serve as a potential biomarker due to its role in the cough reflex. The study aims to discover if ATP production by the airway epithelium is greater in RCC/UCC patients compared with healthy controls, if the epithelium is a source of ATP, whether gene and protein expression related to ATP production differs between these groups and whether ATP release is triggered by mechanical and chemical stimulation. Additionally, the study seeks to determine if biomarker gene expression signatures can differentiate RCC/UCC patients from healthy controls.
Patients with a history of RCC/UCC.
Normal Chest X-ray in the last 5 years.
No Evidence of Airflow Obstruction (FEV1/FVC ratio above LLN)
Cough Severity VAS ≥ 40 mm at screening.
Participants who are currently established on treatment and their chronic cough is well controlled.
Unable to perform acceptable and reproducible spirometry.
Participants with a positive covid-19 test within 2 weeks of screening.
Current smoker or ex-smoker with ≥20 pack year smoking history and abstinence of ≤6 months