Lead author of the study, Dr. Martine Broekema, explains, ‘We found that exposure to cigarette smoke appears to increase the thickness of the epithelium, or lining, of the airways in the lung. This may be the underlying cause of the fact that smoking asthma patients experience more asthma symptoms, such as shortness of breath and phlegm production, compared to non-smoking asthma patients.’
The study included 147 participants with asthma, 66 of whom never smoked, 46 who used to smoke, and 35 who were current smokers. Patients were assessed for the severity of their allergies and asthma and then given surveys in order to determine the extent of their smoke-induced symptoms. Then, they had bronchial biopsies.
Scientists discovered several differences between the group of current smokers and the ex- and non-smokers: Current smokers had more mucus-producing goblet cells in their epithelium and the epithelial cell layer also contained more mucous protein overall when compared to asthmatics who never smoked. In simple terms, this means that smoking affected the severity of phlegm production.
‘Smoking asthmatics also showed a distinct inflammatory profile in their lungs compared to never-smoking asthmatics,’ says Dr. Broekema, adding, ‘Our data suggest that smoking cessation can reverse the thickening of the lining of the airways.’
Interestingly, the researchers found no association between the amount of smoking or the duration and epithelial remodeling.
Dr. Broekema sums the results up this way: ‘This study shows again how important smoking cessation is for pulmonary health, and this appears to be especially true for asthmatic patients. The good news is that quitting appears to have a measurable benefit in these individuals.’