Research article

Persistence of oxidant and protease burden in the airways after smoking cessation

Noora Louhelainen² , Paula Rytilä^1,2 , Tari Haahtela¹ , Vuokko L Kinnula² and Ratko Djukanović³

¹  Department of Medicine, Division of Allergy, University of Helsinki, Finland

²  Department of Medicine, Division of Pulmonary Medicine, University of Helsinki, Finland

³  Division of Infection, Inflammation and Repair, Southampton General Hospital, Southampton, UK

author email corresponding author email

BMC Pulmonary Medicine 2009, 9:25doi:10.1186/1471-2466-9-25

Published:	27 May 2009

Abstract

Background

Oxidative stress is associated with the pathogenesis of cigarette smoke related lung diseases, but longitudinal effects of smoking cessation on oxidant markers in the airways are unknown.

Methods

This study included 61 smokers; 21 with chronic bronchitis or COPD, 15 asthmatics and 25 asymptomatic smokers followed up for 3 months after smoking cessation. Fractional exhaled nitric oxide (FeNO), sputum neutrophil counts, sputum 8-isoprostane, nitrotyrosine and matrix metalloproteinase-8 (MMP-8) were investigated at baseline and 1 and 3 months after smoking cessation.

Results

After 3 months 15 subjects had succeeded in quitting of smoking and in these subjects symptoms improved significantly. Unexpectedly, however, sputum neutrophils increased (p = 0.046) after smoking cessation in patients with chronic bronchitis/COPD. At baseline, the other markers did not differ between the three groups so these results were combined for further analysis. Sputum 8-isoprostane declined significantly during the follow-up at 3 months (p = 0.035), but levels still remained significantly higher than in non-smokers. The levels of FeNO, nitrotyrosine and MMP-8 did not change significantly during the 3 months after smoking cessation.

Conclusion

Whilst symptoms improve after smoking cessation, the oxidant and protease burden in the airways continues for months.