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Open Access Research article

Elevation of sputum matrix metalloproteinase-9 persists up to 6 months after smoking cessation: a research study

Noora Louhelainen1, Harri Stark2, Witold Mazur1, Paula Rytilä3, Ratko Djukanovic4 and Vuokko L Kinnula1*

Author Affiliations

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

2 Finnish Institute of Occupational Health, Helsinki, Finland

3 University of Helsinki, Helsinki, Finland

4 Department of Medicine, Division of Infection, Inflammation and Repair, Southampton General Hospital, Southampton, UK

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BMC Pulmonary Medicine 2010, 10:13  doi:10.1186/1471-2466-10-13

Published: 14 March 2010

Abstract

Background

Smoking cessation is the best possible way to prevent the progression of smoking related airway diseases. However, the effect and time scale of smoking cessation on airway inflammation/remodelling are largely unknown. This prospective study evaluated the effects of smoking cessation on induced sputum (IS) neutrophils, matrix metalloproteinases (MMP-7, -8, -9) and tissue inhibitor of metalloproteinase-1 (TIMP-1).

Methods

A total of 61 subjects participated in the study; 17 stopped smoking for 3 months and 9 for 6 months. The proportion of IS neutrophils and the levels of MMPs and TIMP-1 by ELISA were determined at baseline and at 3 and 6 months after cessation.

Results

In the smokers, baseline IS neutrophils, MMPs and TIMP-1 were significantly higher compared to non-smokers. Levels of MMP-7, -8 and TIMP-1 decreased nearly to those of non-smokers but the levels of MMP-9 increased significantly from the baseline of the same subjects at 3 months after cessation (p = 0.009) with no significant decline at 6 months after cessation.

Conclusions

Sputum MMP-9 remained elevated after 6 months of smoking cessation, which may contribute to ongoing lung damage typical of COPD.