Combined Treatment with Fluoride and Antimicrobial Peptide GH12 Efficiently Controls Caries in vitro and in vivo

Abstract

Combining fluoride and antimicrobial agents enhances regulation of acid and exopolysaccharide production by biofilms. The combination also weakens the acidogenic and aciduric bacteria that contribute to caries, achieving stronger caries-controlling effects with lower concentrations of fluoride. In previous studies, antimicrobial peptide GH12 has been shown to inhibit lactic acid and exopolysaccharide synthesis in various cariogenic biofilm models, and reduce the proportion of acidogenic bacteria and Keyes caries scores in a rat caries model. The current study aimed to elucidate the effect of a combination of low concentrations of sodium fluoride (NaF) and GH12 and to determine the mechanism by which GH12/NaF combination controls caries. The GH12/NaF combination contained 8 mg/L GH12 and 250 ppm NaF. A rat caries model was built, and rat dental plaque was sampled and cultivated on bovine enamel slabs in vitro and subjected to short-term treatment (5 min, 3 times/day). The caries-controlling effects were evaluated using Keyes scoring and transverse microradiography. The results showed that the GH12/NaF combination significantly decreased the onset and development of dental caries, as well as mineral content loss and lesion depth in vitro (P< 0.05). For the caries-controlling mechanisms, 16S rRNA sequencing of in vivo dental plaque revealed that populations of commensal bacteria Rothia spp. and Streptococcus parasanguinis increased in the GH12/NaF group. In contrast, Veillonella, Lactobacillus, and Streptococcus mutans decreased. Furthermore, the GH12/NaF combination significantly reduced biomass, lactic acid, and exopolysaccharides production of in vitro biofilm (P< 0.05). Overall, fluoride and GH12 efficiently arrested caries development and demineralization by regulating the microbiota and suppressing acid and exopolysaccharide production in biofilms.

Effects of Sulforaphene on the Cariogenic Properties of Streptococcus Mutans In Vitro and Dental Caries Development In Vivo

“…The biofilm was washed with PBS buffer, fixed with 4% paraformaldehyde for 2 h, and dehydrated with a gradient of ethanol (25%, 50%, 75%, 90%, and 100%, each for 30 min). The biofilm samples on glass slides were then critical point dried; gold was sputter coated onto them, and the biofilm morphology was examined using scanning electron microscopy (SEM; Apreo 2S, Thermo Scientific) [ 46 ]. The experiment was repeated three times, and the representative images were selected and shown.…”

A Comprehensive Review of Recent Research into the Effects of Antimicrobial Peptides on Biofilms—January 2020 to September 2023

“…Garcia de Carvalho et al used chlorin-e6 (an extract from chlorophyll obtained from Spirulina maxima) conjugated to LL-37 in a nanoemulsion nanocarrier to inhibit biofilms that comprised multiple species during photodynamic therapy [13]. A combination of AMP GH12 with fluoride (GH12/NaF) was found to inhibit the development of caries, regulate the microbiota, and suppress both acid and exopolysaccharide production by biofilms [14]. With respect to the food industry, Gao et al report using a combination of starch/poly (butylene adipate-co-terephthalate) (PBAT) together with AMPs ε-PL and nisin in an antimicrobial film.…”

A Transcriptional Analysis Showing the Effects of GH12 Combined with Fluoride for Suppressing the Acidogenicity of Streptococcus mutans Biofilms

“…The results proved that 8 mg/L of GH12 suppressed the onset and development of dental caries in rats [ 23 ]. Moreover, a stronger caries-controlling effect was observed when GH12 (8 mg/L) was combined with NaF (250 ppm) three times daily for 5 min each in a rodent model [ 24 ]. Therefore, we speculated that GH12 not only disturbed bacterial cell membranes but also directly affected the process of acid production in S. mutans .…”

“…This activity might be attributed to its intracellular interaction with specific PEP-PTS pathways to arrest the transmembrane transportation of carbohydrates or its inhibition of certain enzymes related to carbohydrate metabolism. In addition, since GH12 performed better in the presence of fluoride, we hypothesized that as well as possible cellular activities to arrest the acid production of S. mutans , GH12 also provides fluoride with an extra ability to enter into bacterial cells through its perforating ability [ 24 ], and thus inhibited the acidogenicity of S. mutans more strongly.…”