The pH-Responsive Property of Antimicrobial Peptide GH12 Enhances Its Anticaries Effects at Acidic pH

Wentao Jiang; Junyuan Luo; Yufei Wang; Xiangshu Chen; Xuelian Jiang; Zening Feng; Linglin Zhang

doi:10.1159/000508458

The pH-Responsive Property of Antimicrobial Peptide GH12 Enhances Its Anticaries Effects at Acidic pH

Caries Res. 2021;55(1):21-31. doi: 10.1159/000508458. Epub 2020 Dec 18.

Authors

Wentao Jiang^{1

2}, Junyuan Luo^{1

2}, Yufei Wang^{1

2}, Xiangshu Chen¹, Xuelian Jiang^{1

2}, Zening Feng^{1

2}, Linglin Zhang^{3

4}

Affiliations

¹ State Key Laboratory of Oral Diseases and National Clinical Research Centre for Oral Diseases, Sichuan University, Chengdu, China.
² Department of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
³ State Key Laboratory of Oral Diseases and National Clinical Research Centre for Oral Diseases, Sichuan University, Chengdu, China, zhanglinglin@scu.edu.cn.
⁴ Department of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China, zhanglinglin@scu.edu.cn.

PMID: 33341803
DOI: 10.1159/000508458

Abstract

Dental caries is closely related to the acidification of the biofilms on the tooth surface, in which cariogenic bacteria bring about a dramatic pH decrease and disrupt remineralisation equilibrium upon the fermentation of dietary sugars. Thus, approaches targeting the acidified niches with enhanced anticaries activities at acidic pH are highly desirable. In our previous study, a cationic amphipathic α-helical antimicrobial peptide GH12 (Gly-Leu-Leu-Trp-His-Leu-Leu-His-His-Leu-Leu-His-NH2) was designed with good stability, low cytotoxicity, and excellent antibacterial effects. Considering its potent antibacterial activity against the acidogenic bacteria and its histidine-rich sequence, it was speculated that GH12 might show enhanced antimicrobial effects at an acidic pH. In this study, the pH-responsive property of GH12 was determined to evaluate its potential as a smart acid-activated anticaries agent. GH12 possessed much lower minimal inhibitory concentrations and minimal bactericidal concentrations against various kinds of bacteria at pH 5.5 than at pH 7.2. Employing Streptococcus mutans, the principal caries pathogen, as the model system, it was found that GH12 showed much stronger bactericidal effects on both planktonic S. mutans and S. mutans embedded in the biofilm at pH 5.5. In addition, short-term treatment with GH12 showed much more effective inhibitory effects on water-insoluble exopolysaccharides synthesis and lactic acid production of the preformed S. mutans biofilm at pH 5.5. As for the mechanism exploration, it was found that the net positive charge of GH12 increased and the tryptophan fluorescence intensity heightened with the peak shifting towards the short wavelength at pH 5.5, which demonstrated that GH12 could be more easily attracted to the anionic microbial cell membranes and that GH12 showed stronger interactions with the lipid membranes. In conclusion, acidic pH enhanced the antibacterial and antibiofilm activities of GH12, and GH12 is a potential smart anticaries agent targeting the cariogenic acidic microenvironment.

Keywords: Antimicrobial peptide; Biofilm; Dental caries; Streptococcus mutans; pH-responsive peptide.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Anti-Bacterial Agents / pharmacology
Biofilms
Dental Caries* / drug therapy
Humans
Hydrogen-Ion Concentration
Microbial Sensitivity Tests
Pore Forming Cytotoxic Proteins
Streptococcus mutans

Substances

Anti-Bacterial Agents
Pore Forming Cytotoxic Proteins