Novel lactotransferrin-derived synthetic peptides suppress cariogenic bacteria in vitro and arrest dental caries in vivo

Abstract

Objectives:The aim of the study was to design and synthesise novel lactotransferrin-derived antimicrobial peptides (AMPs) with enhanced antibacterial activity against cariogenic bacteria. Methods: We obtained the LF-1 (WKLLRKAWKLLRKA) and LF-2 (GKLIWKLLRKAWKLLRKA) AMPs, based on the N-terminal functional sequence of lactotransferrin, and characterised their physicochemical properties and secondary structure. Their antibacterial activity against caries-associated bacteria was evaluated using bacterial susceptibility and time-killing assays, as well as transmission electron microscopy (TEM). The antibiofilm activity against Streptococcus mutans biofilms was determined using biofilm susceptibility assays and confocal laser scanning microscopy (CLSM). A rodent model of dental caries was adopted to evaluate their anticaries effectiveness in vivo. Results: Both peptides possessed an α-helical structure with excellent amphipathicity. LF-1 was effective against S. mutans and Actinomyces species, whereas LF-2 showed more potent antibacterial activity than LF-1 against a broader spectrum of tested strains. Both peptides inhibited the formation of S. mutans biofilm starting at 8 μmol/L and exerted effective eradication of S. mutans in preformed biofilms. Both peptides exhibited satisfactory biocompatibility and exerted significant anticaries effects in a rodent model. Conclusions: Both lactotransferrin-derived peptides displayed strong antimicrobial activity against cariogenic bacteria and S. mutans biofilm in vitro and effectively inhibited dental caries in vivo.

Novel Lactotransferrin-Derived Antimicrobial Peptide LF-1 Inhibits the Cariogenic Virulence Factors of Streptococcus mutans

“…In our previous studies, we successfully developed a novel lactotransferrin-derived AMP, LF-1, and evaluated its antibacterial activity against multiple caries-associated bacterial strains [ 19 ]. LF-1 demonstrated the most notable antibacterial activity against the tested strains of S. mutans , with an MIC of 8 μmol/L.…”

“…Among the AMPs utilised in caries research, we successfully developed a novel AMP, LF-1, based on the functional domain of lactotransferrin using a biomimetic strategy. In previous studies, LF-1 displayed potent antibacterial activity against S. mutans and its biofilm and induced notable protection in an S. mutans -mediated rodent model of dental caries [ 19 ]. Compared with oral commensal Streptococcus species ( S. sanguinis and S. gordonii ), LF-1 selectively targeted S. mutans with preferable membrane affinity.…”

“…Therefore, this study aimed to explore the effects of LF-1 on the cariogenic virulence factors of S. mutans and evaluate the changes in virulence-associated enzyme and gene transcription levels. We adopted relatively low drug concentrations (≤8 μmol/L) as the treatment concentrations to avoid the strong bactericidal effects of LF-1 [ 19 ]. The null hypothesis was that LF-1 does not suppress S. mutans cariogenic virulence factors or the expression of key enzymes and virulence-associated genes.…”

A Novel Dental Caries Model Replacing, Refining, and Reducing Animal Sacrifice

“…Keyes [14] was the first to describe caries-scoring over hemi-sections rat molars. His scoring method, using murexide dye, is a common method still in use [33][34][35]. Zhang et al [34] described the radiographic analysis of caries induced in rats; µCT scans were used to compare the mineral density of rats' molar enamel after calibration with hydroxyapatite standards of appropriate density.…”

Nicotinamide could reduce growth and cariogenic virulence of Streptococcus mutans

“…The S. mutans biofilms, cultivated on glass coverslips as described previously [ 26 , 27 ], were analyzed for biofilm thickness and bacterial viability using a Leica DMIRE2 confocal laser scanning microscope (CLSM) (Leica). One µM of Alexa Fluor 647-labeled dextran conjugate (Life Technologies, Grand Island, NY) was added to overnight cultures of S. mutans UA159 grown in BHIS.…”