EFFECT OF LACTOFERRICIN-B, A PEPSIN-GENERATED PEPTIDE OF BOVINE LACTOFERRIN, ON ESCHERICHIA-COLI HB101 (PRI203) ENTRY INTO HELA-CELLS

Bovine lactoferrin and a pepsin-generated peptide of bovine lactoferrin, known as lactoferricin B, were tested for an ability to influence the cell-invasive properties of an Escherichia coli HB 101 strain carrying the plasmid pRI203, which encodes the Yersinia pseudotuberculosis inv gene. At non-cytotoxic and non-bactericidal concentration (0.5 mg/ml) lactoferricin B lowered by about tenfold the cell invasion capability of E. coli HB 101 (pRI203), whereas no effect was observed when bovine lactoferrin was added during the infection of HeLa cell monolayers. The step of the invasion process affected by lactoferricin B was the internalization since the adhesion of bacteria to HeLa cells was unaltered in the presence of the peptide. Latex beads coated with lactoferricin B bound to HeLa cell monolayers and induced the agglutination of bacterial cells, indicating that this highly cationic peptide interacts directly with both eukaryotic and bacterial surfaces. Moreover, we demonstrated that the anti-invasive effect induced by lactoferricin B was reversed when the medium was supplemented with Ca2+, Mg2+ and Fe2+ ions which diminished its affinity binding. Our findings suggest that lactoferricin B effectiveness towards E. coli HB 101 (pRI203) invasion is correlated to its binding capability on the eukaryotic and bacterial cell surfaces.