Antimicrobial peptide GH12 targets Streptococcus mutans to arrest caries development in rats

Background:Targeting Streptococcus mutans, the principle cariogenic bacterium, could prove to be an effective means of preventing dental caries. A de novo designed antimicrobial peptide, GH12, has shown bactericidal effects on S. mutans and inhibitory effects on virulence and regulatory systems of S. mutans. However, the effects of GH12 on caries remain to be elucidated.Objectives: The objectives of this study were to evaluate the direct effects of GH12 on caries and numbers of S. mutansin vivo.Design: The Keyes score was evaluated in a rodent model and in vivo S. mutans was quantified by qPCR. To further interpret the in vivo anticaries efficacy, an in vitro biofilm model using short-term treatments with GH12 mimicked treatments in vivo was adopted. Results: In vivo data showed that GH12 at 8 mg/L reduced the incidence and severity of caries. Furthermore, GH12-treated animals had less S. mutans infection. In vitro data revealed that GH12 reduced the number of S. mutans within the biofilm, as well as reducing lactic acid and water-insoluble EPS synthesis of S. mutans biofilms. Afterwards, all rats showed no significant difference in weight gain, and no sign of harm to the mucosa, indicating that GH12 possessed good biocompatibility in vivo.Conclusion: Due to the combined inhibitory effects of GH12 on the biomass and cariogenic properties of S. mutans biofilms, the population of S. mutans in vivo was reduced, residual S. mutans biofilms were less acidic and compact, and thereby the onset and development of caries were arrested. Such findings collectively certified the clinical prospects for GH12