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

BMC Pulm Med. 2010 Mar 14;10:13. doi: 10.1186/1471-2466-10-13.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Humans
  • Male
  • Matrix Metalloproteinase 7 / metabolism
  • Matrix Metalloproteinase 8 / metabolism
  • Matrix Metalloproteinase 9 / metabolism*
  • Middle Aged
  • Neutrophils / metabolism
  • Prospective Studies
  • Smoking / metabolism*
  • Smoking Cessation*
  • Sputum / enzymology*
  • Tissue Inhibitor of Metalloproteinase-1 / metabolism


  • Tissue Inhibitor of Metalloproteinase-1
  • MMP7 protein, human
  • Matrix Metalloproteinase 7
  • Matrix Metalloproteinase 8
  • Matrix Metalloproteinase 9