Smoking is the most important factor causing chronic obstructive pulmonary disease (COPD). It induces lung inflammation, which is thought to play a substantial role in the development and progression of this disease. Smoking cessation is the only treatment that has shown to reduce symptoms and to slow down progression of COPD.

Wim Timens, Brigitte W.M. Willemse (Department of Pathology, University Medical Centre Groningen, The Netherlands) and their team have studied effects of smoking cessation in patients with COPD, compared to smokers without any symptoms. In this longitudinal study the authors particularly focused on the effect on airway inflammation.

Two groups of smokers, 28 with COPD and 25 with normal lung function were included in a one-year smoking cessation programme.

Effects of smoking cessation on airway inflammation were investigated before stopping smoking and one year after successfully quitting, through airway biopsies (small pieces of tissue from the inner part of the airway wall) and sputum samples, coming from the lumen of the central part of the airways.

In the 16 asymptomatic smokers who successfully quit smoking, parameters of inflammation either significantly reduced or did not change. In the 12 successful quitters with COPD however, airway inflammation persisted in airway biopsies at 12 months and several inflammatory parameters even significantly increased. This does not necessarily mean that smoking cessation has no positive effect with respect to treatment of disease. The authors indicate that it is important to realise that inflammation is not only a phenomenon underlying disease development, but that this is also an essential component in repair of the damage associated with disease.

As hardly any tissue damage is present in normal subjects but is considerable in COPD patients, the meaning of persistence or increase of inflammation is not readily clear.

The Dutch team suggests that the observed persistent airway inflammation in patients with COPD is related to repair of tissue damage in the airways.

More detailed research into the further characteristics of the persistent inflammation should elucidate whether this reflects a beneficial or detrimental effect. If the inflammation is still a disease related effect, it can be concluded that smoking cessation has to last longer than one year to show effects, and that perhaps focused anti-inflammatory strategies could be of help and should be developed.

It is also important to realise that when this inflammation represents a beneficial effect, related to convalescence, further measures should not be taken to reduce the inflammation.

Title of the original article:
Effect of 1-year smoking cessation on airway inflammation in COPD and asymptomatic smokers

The European Respiratory Journal is the peer-reviewed scientific publication of the European Respiratory Society (more than 7,500 specialists in lung diseases and respiratory medicine in Europe, the United States and Australia).


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