Lactoferrin and oral diseases: current status and perspective in periodontitis

Abstract

Lactoferrin (Lf), an iron-binding glycoprotein able to chelate two ferric ions per molecule, is a component of human secretions synthesized by exocrine glands and neutrophils in infection/inflammation sites. Lactoferrin in saliva represents an important defence factor against bacterial injuries including those related to Streptococcus mutans and periodontopathic bacteria through its ability to decrease bacterial growth, biofilm development, iron overload, reactive oxygen formation and inflammatory processes. A growing body of research suggests that inflammatory periodontal disease involves a failure of resolution pathways to restore tissue homeostasis. There is an important distinction between anti-inflammation and resolution; anti-inflammation is pharmacologic intervention in inflammatory pathways, whereas resolution involves biologic pathways restoring inflammatory homeostasis. An appropriate regulation of pro-inflammatory cytokine synthesis might be useful in reducing periodontal tissue destruction. Recently, the multifunctional IL-6 is emerging as an important factor able to modulate bone, iron and inflammatory homeostasis. Here, we report an overview of Lf functions as well as for the first time Lf anti-inflammatory ability against periodontitis in in vitro model and observational clinical study. In in vitro model, represented by gingival fibroblasts infected with Prevotella intermedia, Lf exerted a potent anti-inflammatory activity. In the observational clinical trial performed through bovine Lf (bLf) topically administered to volunteers suffering from periodontitis, bLf decreased cytokines, including IL-6 in crevicular fluid, edema, bleeding, pocket depth, gingival and plaque index, thus improving clinical attachment levels. Even if other clinical trials are required, these results provide strong evidence for a instead of an therapeutic potential of this multifunctional natural protein.