Cigarette smoke alters primary human bronchial epithelial cell (PBEC) differentiation at air-liquid interface (ALI) and induces expression of CD105 and CD146

Abstract

Dys-regulation of airway epithelial cell function related to cigarette smoke exposure plays an important role in the pathophysiology of COPD. CD105, a component of TGF-β complex, and CD146, an epithelial-mesenchymal transition inducer, are adhesion molecules involved in cellular proliferation, differentiation, transmigration and tissue remodelling. After validation of an ex vivo ALI culture of PBEC, we assessed the effect of long-term cigarette smoke extract (CSE) exposure on epithelium regeneration and differentiation. Endobronchial biopsy specimens (EBBs) were obtained from 8 controls (C) and 9 COPD. ALI cultures from EBBs of C were exposed to CSE for 7, 14, 21 days. Transepithelial Electrical Resistance (TEER) measurements were performed. CD105 and CD146 expression was evaluated in ALI, before or after CSE, by Western Blot and in EBBs by immunohistochemistry. TEER values measured over 7 to 21 days of PBEC differentiation decreased by 18% and 29%, when compared to untreated samples, with 5% and 10% CSE, respectively. In PBEC-ALI, CD105 and CD146 expression was increased by CSE. CD105 and CD146 epithelium immunoreactivity was higher in EBBs of COPD than C. Morphometric analysis of EBBS from COPD showed an increase of CD105 and CD146 in the metaplastic areas of the epithelium. Chronic exposure to cigarette smoke may be able to induce an altered epithelium homeostasis and regenerative capacity, as a consequence of dys-regulation in differentiation mechanisms. CD105 and CD146 overexpression might be involved in outside-in signalling of pro-oxidative processes leading to an abnormal tissue remodeling and progression of COPD.