Epithelial secretory proteins as biomarkers in COPD

Biomarkers of diagnosis and disease progression in chronic obstructive pulmonary disease (COPD) should provide useful tools to prevent and treat the disease at an early stage. The epithelial surface represents a critical interface between the respiratory tract and the environment. It is therefore likely that secretory products from epithelial cells could be influenced by environmental changes and disease states. Using immunostaining, we specifically investigated secretory component (SC) and Clara cell protein (CCP), both derived from respiratory epithelial cells, in bronchial tissue from severe COPD patients. SC and CCP were decreased in particular in small airways from COPD patients compared with smokers without COPD, and the decrease of SC correlated with the degree of airway obstruction. Using Ki-67 as a marker of cell proliferation, we observed an increase of proliferating cells in small airways from COPD also correlating with severity of airway obstruction. By contrast epithelial expression of galectin-3, a lectin known to promote cell proliferation and actvation of inflammatory cells was increased in airways of COPD. These data illustrate changes in epithelium-derived products associated with COPD suggesting their potential rote as biomarkers in the diagnosis and follow-up of this disease