Role of chronic exsposure to cigarette smoke on endoglin/CD105 expression in airway epithelium.

Dysregulation of airway epithelial cell function related to cigarette smoke exposure plays an important role in the pathophysiology of COPD and is associated to tissue damage and disease severity. CD105 is a component of the receptor complex of TGF-β, a pleiotropic cytokine involved in cellular proliferation, differentiation and migration. CD105 regulates the expression of different components of the extracellular matrix suggesting a role of CD105 in cellular transmigration and remodeling processes. The aim of the present study was to investigate the expression of endoglin/CD105 in airway epithelium of COPD patients and its involvement in tissue remodeling and progression of COPD. We evaluated the immunoreactivity for CD105 expression in bronchial biopsies isolated from COPD patients and healthy controls (HC). The analysis of metaplastic epithelium was performed in bronchial biopsies by Image Analysis software (Leica Quantimet system). Finally, we investigated the expression of CD105 protein receptor in human bronchial epithelial cells (16HBE cells) exposed to 5% Cigarette Smoke Extract (CSE) for 12 days by western blot. We found that the CD105 immunoreactivity was significantly higher in bronchial epithelium of COPD than HC. Morphometric analysis of bioptic samples of COPD showed an increase of the immunoreactivity for CD105 in the area of metaplastic than in not metaplastic epithelium. Long term exposure to CSE significantly up-regulated CD105 expression in 16HBE. Chronic inflammation due to cigarette smoke might play a critic role on the alteration of CD105 protein expression in COPD, promoting tissue remodeling, angiogenesis and dysregulation of physiological reparative mechanisms, leading to squamous metaplasia.