Tobacco smoke is a major risk factor in the development of COPD. Secondhand smoke (SHS) exposure is a known risk factor in asthma, bronchitis, and coronary artery disease. Elastin is a recognized target for injury in COPD, and the amino acids desmosine and isodesmosine (D/I), which are specific for elastin degradation, are elevated in COPD. This study determined whether exposure to SHS affects elastin degradation in asymptomatic individuals.
Two cohorts of asymptomatic individuals without evidence of respiratory or circulatory disease, exposed to SHS, were studied. Both cohorts comprised normal nonsmokers, active smokers, and those exposed to SHS. D/I were measured in plasma and quantified by high-performance liquid chromatography and tandem mass spectrometry by published methods. Plasma cotinine, a metabolite of nicotine, was also measured.
In each cohort, the levels of D/I in plasma were statistically significantly higher in secondhand-smoke-exposed subjects than in the normal nonexposed subjects. Smokers had the highest levels of D/I but their levels were not statistically significantly higher than those of the secondhand-smoke-exposed. Cotinine levels were elevated in secondhand-smoke-exposed subjects and active smokers but not in most nonsmoking control subjects.
Results indicate a tissue matrix effect of degradation of body elastin from SHS exposure and possible lung structure injury, which may result in COPD. Long-term studies of individuals exposed to SHS for the development of COPD are warranted.