The effect of lactoferrin on oral bacterial attachment

Introduction: Lactoferrin (Lf), an iron-binding salivary glycoprotein, plays an important role in human innate defense against local mucosal infection. We hypothesized that Lf interferes with initial oral bacterial attachment to surfaces by iron sequestration, so inhibiting subsequent biofilm formation. The objective was to investigate the effect of Lf on the early stages of single-species and multi-species oral biofilm development. Methods: Streptococcus gordonii, Streptococcus mutans, Fusobacterium nucleatum and Porphyromonas gingivalis were used in this study. Glass disks of a two-track flow cell coated with flowing artificial saliva (0.3 ml/min) with and without Lf (100 mu g/ml) were used for studying bacterial attachment (3 h, 37 degrees C). Attachment was also examined by incubating single or multiple species of test bacteria (10(7) colony-forming units/ml) with Lf-coated (20-100 mu g/ml) and uncoated glass slides. The effects of beta-lactoglobulin, 2,2'-dipyridyl (25-100 mu g/ml), an iron chelator, and FeCl3 on attachment were also examined. Results: Lf inhibited the initial attachment of S. gordonii (50.3%, P < 0.05) but not that of F. nucleatum and P. gingivalis. However, the attachment of a dual-species biofilm containing S. gordonii (i.e. S. gordonii/F. nucleatum or S. gordonii/P. gingivalis) was significantly reduced (48.7% or 62.1%, respectively, P < 0.05) in the presence of Lf. beta-Lactoglobulin did not affect the attachment of S. gordonii. In the presence of 100 mu m 2,2'-dipyridyl, attachment of S. gordonii was reduced by 53.87%. No reduction in attachment was noted in S. gordonii pretreated with Lf (100 mu g/ml) and FeCl3 (20-200 mu m). Conclusion: Lf suppresses initial attachment of S. gordonii and S. gordonii coaggregates by iron sequestration. This may lead to subsequent inhibition of oral biofilm development.