Airway epithelial wound repair: role of carbohydrate sialyl Lewis

Airway epithelial wound repair: role of carbohydrate sialyl Lewisx. Am J Physiol Lung Cell Mol Physiol 291: L828-L836, 2006. First published June 2, 2006; doi:10.1152/ajplung.00120.2006. Epithelial repair is a complex cellular and molecular process, the details of which are still not clearly understood. Plasma membrane glycoconjugates can modulate cell function by altering the function of protein and lipids. Sialyl Lewis(x) (sLe(x)), a fucose-containing tetrasaccharide, decorates membrane-bound and secreted proteins and mediates cell-cell interaction. In the present study we investigated the role of sLe(x) in airway epithelial repair. Using immunohistochemistry, we showed an increased expression of sLe(x) in areas of damaged bronchial epithelium compared with intact regions. Confluent monolayers of airway epithelial cells were mechanically wounded and allowed to close. Wounded monolayers were photographed for wound closure kinetics, fixed for immunocytochemical studies, or subjected to RNA extraction. Examining the expression of different alpha 1,3-fucosyltransferases (FucT), enzymes that mediate the final step in the synthesis of sLe(x), we found that FucT-IV was the common gene expressed in all cell lines and primary airway epithelial cells. We demonstrated an increased expression of sLe(x) over time after mechanical injury. Blocking of sLe(x) with an inhibitory antibody completely prevented epithelial repair. Our data suggest an essential functional role for sLe(x) in epithelial repair. Further studies are necessary to explore the exact mechanism for sLe(x) in mediating cell-cell interaction in bronchial epithelial cells to facilitate epithelial migration and repair.