Exhaled 8-isoprostane as a new non-invasive biomarker of oxidative stress in cystic fibrosis
- Paolo Montuschib,
- Sergei A Kharitonova,
- Giovanni Ciabattonib,
- Massimo Corradia,
- Liesbeth van Rensena,
- Duncan M Geddesa,
- Margaret E Hodsona,
- Peter J Barnesa
- aDepartment of Thoracic Medicine, Imperial College School of Medicine at the National Heart and Lung Institute, London SW3 6LY, UK, bInstitute of Pharmacology, School of Medicine, Catholic University of the Sacred Heart, Roma, Italy
- Professor P J Barnes
- Received 12 July 1999
- Revision requested 20 September 1999
- Revised 5 November 1999
- Accepted 25 November 1999
Abstract
BACKGROUND Cystic fibrosis is characterised by oxidative stress in the airways. Isoprostanes are prostaglandin isomers formed by free radical catalysed peroxidation of arachidonic acid. 8-Isoprostane is increased in interstitial lung diseases, asthma, chronic obstructive pulmonary disease, and adult respiratory distress syndrome. Exhaled nitric oxide (NO) and carbon monoxide (CO) are biomarkers of inflammation and oxidative stress in the airways, respectively.
METHODS Concentrations of 8-isoprostane in the breath condensate of 10 normal subjects and 19 patients with stable cystic fibrosis were measured using an enzyme immunoassay (EIA). Breath condensate is a non-invasive method of collecting airway secretions. Exhaled nitric oxide (NO) and carbon monoxide (CO) levels were measured by a chemiluminescence analyser.
RESULTS Concentrations of 8-isoprostane in the breath condensate of patients with stable cystic fibrosis were increased about threefold compared with normal subjects (42.7 (4.5) pg/ml vs 15.2 (1.7) pg/ml; p<0.005, 95% CI 14.6 to 40.9). 8-Isoprostane concentrations were negatively correlated with forced expiratory volume in one second in patients with cystic fibrosis (r = −0.61; p<0.005). Exhaled CO was also increased in patients with cystic fibrosis compared with normal subjects (6.7 (1.2) ppm vs 2.9 (0.3) ppm; p<0.05, 95% CI 0.2 to 7.4). 8-Isoprostane concentrations were significantly correlated with CO levels (r = 0.66; p<0.002).
CONCLUSIONS The results of this study show that oxidative stress is increased in cystic fibrosis and may be quantified by measuring 8-isoprostane concentrations in breath condensate.
