Antimicrobial Peptide P-113-DPS Suppresses the Cariogenic Virulence of <i>Streptococcus mutans</i>

Dental caries is a widespread and contagious chronic infectious condition. As the principal cariogenic bacterium involved in dental caries, <i>Streptococcus mutans</i> (<i>S. mutans</i>) possesses cariogenicity-related properties, including acidogenicity, aciduricity, and exopolysaccharide (EPS) synthesis. Our previously designed peptide, P-113-DPS, has demonstrated antibacterial effects on <i>S. mutans</i>; however, its detailed impact on its cariogenic virulence factors remains unclear. This study focused on assessing changes in these factors following treatment with P-113-DPS. Furthermore, it aimed to investigate alterations in virulence-associated gene expression <i>in vitro</i>. The basic viability of <i>S. mutans</i> after P-113-DPS treatment was evaluated using a growth curve assay and 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide staining assay. Acidogenicity was assessed through monitoring pH drop and lactate dehydrogenase activity, while aciduricity was evaluated through measuring survival rates in a lethal acidic environment. Additionally, EPS synthesis was analyzed using the anthrone sulfuric acid method, and structural observations were performed with confocal laser scanning and scanning electron microscopy. Finally, the changes in gene expression were examined utilizing quantitative real-time PCR (qPCR). P-113-DPS inhibited the growth and cell viability of <i>S. mutans</i>. Treatment with P-113-DPS resulted in decreased acidogenicity and aciduricity, evidenced by reduced acid production and survival rates at pH 5.0. Additionally, P-113-DPS suppressed the biofilm formation and EPS synthesis. Moreover, qPCR analysis revealed that P-113-DPS downregulated the expression of <i>S. mutans</i> virulence-associated genes. In conclusion, P-113-DPS exhibited strong antimicrobial properties and effectively suppressed the cariogenic virulence traits of <i>S. mutans</i> <i>in vitro</i> by downregulating virulence-associated genes, highlighting its promising anticaries potential.