Background and objective: Chronic obstructive pulmonary disease is characterized by persistent and modified inflammatory responses in lung. Human sirtuin, an antiaging and antiinflammatory protein, is a metabolic NAD(+)-dependent protein/histone deacetylase that regulates proinflammatory mediators by deacetylating histone and nonhistone proteins. The aim of our study was to compare the expression of sirtuin in large and small airways in nonsmokers, asymptomatic smokers, and smokers with chronic obstructive pulmonary disease.
Material and methods: A total of 12 nonsmokers, 14 asymptomatic smokers, and 12 smokers with moderate chronic obstructive pulmonary disease were enrolled into the study. Immunohistochemical and Western blot methods were used to analyze sirtuin expression in the airways.
Results: The obtained results showed the nonuniform sirtuin expression throughout the bronchial tree. Smokers both with and without chronic obstructive pulmonary disease had decreased sirtuin expression in large airways. However, in small airways, sirtuin expression was decreased only in patients with chronic obstructive pulmonary disease. In addition, a correlation between airflow limitation, smoked pack-years and the number of sirtuin-positive cells in airways was found.
Conclusions: Smoking is characterized by suppressed sirtuin expression in large airways, whereas chronic obstructive pulmonary disease is characterized by more severe suppression of sirtuin expression both in large and small airways.