ICAM-1 and α3β1 expression by bronchial epithelial cells and their in vitro modulation by inflammatory and anti-inflammatory mediators

Background: Adhesion molecules are involved in inflammatory and repair processes of the bronchial epithelium. ICAM-1 is mainly involved in inflammatory reactions, whereas integrins, such as α3β1, are mainly involved in repair processes.

Methods: Using bronchial biopsies from 10 asthmatics and eight controls, we first evaluated by immunohistochemistry expression of α3β1 and ICAM-1 in intact and damaged epithelium. Then, using the human pulmonary epithelial cell line WI-26 VA, we studied, by flow-cytometry, the modulation of ICAM-1 and α3β1 expression, and, by ELISA, the release of fibronectin by proinflammatory cytokines, such as IL-5, and anti-inflammatory cytokines, such as IL-4, TGF-β, and EGF.

Results: α3β1 expression was slightly higher in asthma than in controls, as well as in damaged epithelium than in undamaged epithelium. ICAM-1 expression was higher in asthma than in controls, and similarly distributed in intact or damaged epithelium. In vitro, α3β1 was significantly increased by TGF-β, EGF, and IL-4, and significantly decreased by IL-5. Fibronectin release was significantly increased by TGF-β and IL-4, unchanged by EGF, and slightly but significantly decreased by IL-5. ICAM-1 expression was significantly decreased by TGF-β and IL-4, unchanged by EGF, and significantly increased by IL-5.

Conclusions: These differences in adhesion molecule expression and fibronectin release may be important in epithelial cell inflammation and repair.