Involvement of glycosaminoglycans in the attachment of pneumococci to nasopharyngeal epithelial cells

Streptococcus pneumoniae is a major bacterial pathogen involved in the development of otitis media. The pathogenic mechanisms of this middle ear disease, including the bacterial adherence mechanisms to the mucosal epithelial cells of the host, are poorly understood. In this study, the role of glycosaminoglycans in the adhesion of pneumococci to mucosal epithelial cells is examined. Both nasopharyngeal epithelium from rats and an oral epithelial cell line were used for pneumococcal adherence experiments. Preincubation of pneumococci with heparin, heparan sulfate (HS) and to a lesser extent, chondroitin 4-sulfate (C-4S), was found to inhibit attachment of S. pneumoniae to oral epithelial cells, while dermatan sulfate and hyaluronate did not interfere with pneumococcal binding. Enzymatic removal of HS moieties by heparinase III from nasopharyngeal epithelial cells abolished the attachment of pneumococci to nasopharyngeal epithelium. This study demonstrates that heparin, HS and C-4S are involved in pneumococcal binding to mucosal epithelial cells. This knowledge may contribute to the development of a new prophylactic strategy for otitis media.