Adherence of group A streptococci to fibronectin on oral epithelial cells

The possibility that fibronectin on the surface of oropharyngeal cells may serve as a receptor for the binding of group A streptococci (Streptococcus pyogenes) was investigated. Purified human plasma fibronectin inhibited the adherence of group A streptococci to oral epithelial cells in a dose-dependent manner. The relative amounts of fibronectin available on oral epithelial cells correlated closely with the ability of these cells to bind streptococci. Group A streptococci agglutinated latex beads containing covalently linked fibronectin on their surface, and this agglutination could be inhibited by lipoteichoic acid, the adhesion that mediates attachment of group A streptococci to epithelial cells. Gelatin and the alpha 1 chain of type I collagen partially inhibited both the adherence of streptococci to oral epithelial cells and the binding of radiolabeled fibronectin to streptococci; however, the purified fibronectin-binding peptide of collagen, alpha 1 (I)CB7, inhibited neither. The binding of radiolabeled fibronectin to streptococci was inhibited by lipoteichoic acid. These results suggest that fibronectin on oral epithelial cells serves as a lipoteichoic acid-sensitive receptor for group A streptococci.