Modelling IPF-associated chronic cough: role for oxidative stress?

Introduction: Chronic cough is a key symptom that plagues the lives of IPF patients, indeed, it is often the reason the disease is initially diagnosed. The aim of this project was to develop a pre-clinical model of IPF-associated cough and compare the mediator profiles with clinical samples, to aid in the search for effective treatments. Methods: Male guinea pigs (around 325g) were intratracheally dosed with vehicle (saline) or bleomycin (6 USP/kg) and coughs were quantified through manual observation of in-cage video footage, by watching 4.5 hours a day, for 3 weeks. Lung tissue, bronchoalveolar lavage fluid (BALF) and blood was harvested from a parallel group of animals. These were used to assess the extent of fibrosis and measure mediator production (e.g. a marker of oxidative stress: 8-isoprostane). Human BALF was obtained from IPF patients and healthy controls. Results: Spontaneous coughing was recorded in guinea pigs given bleomycin, which was associated with an increase in lung fibrosis and BALF 8-isoprostane (a marker of oxidative stress). We noted similar increases in BALF 8-isoprostane levels in the clinical samples. Conclusions: We have developed a preclinical model to aid in the search for a treatment for IPF-associated coughing. Furthermore, initial data suggests that an increase in oxidative burden (a known trigger of coughing) could be an attractive target.