Airway inflammation in asthma: basic and clinical science

S1 INCREASED TACHYKININ LEVELS IN THE AIRWAYS OF ASTHMATIC PATIENTS AND CHRONIC COUGH PATIENTS WITH COEXISTENT GASTRO-OESOPHAGEAL REFLUX DISEASE

R. N. Patterson¹, B. T. Johnston¹, L. G. Heaney^1,2, L. P. A. McGarvey¹. ¹Department of Medicine, Queens University Belfast, Belfast, N Ireland; ²Regional Respiratory Centre, Belfast City Hospital, Belfast, N Ireland

Background: Gastro-oesophageal reflux disease (GORD) may aggravate airway diseases including asthma and chronic cough. One postulated mechanism is via a vagally mediated distal oesophageal-tracheobronchial reflex associated with airway sensory nerve activation and tachykinin release. In this study we tested the hypothesis that patients with airways disease and GORD have increased airway tachykinin levels compared to those without GORD.

Methods: The study population consisted of 32 patients (all non-smokers) attending the chest clinic at the Belfast City Hospital. Sixteen subjects with asthma (eight female, mean age 55.2 years, FEV1 61–112% predicted) and 16 with non-asthmatic chronic cough (11 female, mean age 61.8 years, FEV1 80–127%predicted) were recruited randomly and underwent 24 hour oesophageal pH monitoring. GORD was defined as increased total oesophageal acid exposure (% total time >4.9% at the distal probe). All subjects underwent sputum induction and differential cell count were obtained and concentrations of substance P (SP), Neurokinin A (NKA), albumin, and a2-macroglobulin were measured in sputum supernatants.

Results: Comparing all subjects, the mean SP and NKA levels were significantly higher in patients with GORD compared to those without GORD (SP; 1433.97 pg/ml versus 905.95 pg/ml, p = 0.026, NKA, 81.04 pg/ml v 49.13 pg/ml, p = 0.014). Significantly increased tachykinin levels were also measured when asthmatic patients with GORD were compared to those without GORD, (SP; 1508.37 pg/ml v 736.68 pg/ml, p = 0.035, NKA; 103.15 pg/ml v 56.77 pg/ml, p = 0.02). Although SP and NKA levels were also increased in the cough patients with GORD this did not reach statistical significance, (SP; 1534.71 pg/ml v 1088.75 pg/ml, p = 0.198, NKA, 55.99 pg/ml v 49.77 …