Background: The airway epithelium acts as a protective barrier, separating the external environment from the underlying tissue. Daily challenges result in damage to the epithelium that, in normal individuals, is quickly and effectively repaired. In respiratory diseases, such as asthma, this repair is compromised. Following injury to the epithelium, plasma leaks into the airway lumen acting as a protective protein cap. Carbohydrates are mediators of epithelial repair, however, the associated regulatory proteins remain unknown.
Objective: To identify mediators of epithelial repair based on their carbohydrate moieties using an in vitro wound repair culture model of human airway epithelial cells (1HAEo(-)).
Methods: Using the lectin Allomyrina dichotoma agglutinin (AlloA) as a tool, ligands essential in the repair of damaged epithelium were characterized. AlloA was subsequently used to purify and identify a glycoprotein associated with epithelial repair.
Results: The addition of AlloA to the media of mechanically wounded monolayers inhibited repair. Fetuin, a highly glycosylated serum protein, was identified as a glycoprotein bound by AlloA. The addition of fetuin to serum starved monolayers stimulated wound closure.
Conclusion: These results indicate that following mechanical injury to the epithelium, serum glycoproteins, not only provide a protective barrier, but also are involved in the initiation of wound closure.