Efeito dos peptídeos salivares derivados de estaterina e histatina na aderência do Streptococcus mutans e na desmineralização do esmalte provocada por biofilmes cariogênicos

Author(s)

Lina María Marín Gallón

• Document type: Doctoral Thesis
• Press: Piracicaba, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Odontologia de Piracicaba
• Defense date: 2019-08-30

Examining board members

Jaime Aparecido Cury; Walter Luiz Siqueira; Karina Gonzales Silverio; Antônio Pedro Ricomini Filho; Fausto Medeiros Mendes

• Advisor: Jaime Aparecido Cury

Abstract

Dental biofilm is formed onto dental surfaces covered by a layer of specific salivary proteins and peptides named acquired enamel pellicle (AEP). It was previously demonstrated that the statherin- and histatin-derived engineered salivary peptides DR9-DR9 and DR9-RR14 were able to reduce enamel demineralization and displayed antimicrobial activity against Streptococcus mutans, respectively. However, these studies were carried under experimental conditions that did not mimic caries development induced by biofilm and sucrose exposure, the most cariogenic dietary sugar. In this thesis we assessed the effect of the engineered salivary peptides on 1) the adherence of S. mutans to hydroxyapatite (HAp), and 2) the reduction of enamel demineralization, using a validated S. mutans cariogenic biofilm model. We hypothesized that DR9-DR9 and DR9-RR14 would reduce S. mutans adherence and the cariogenicity of the biofilms, protecting enamel against demineralization. To test this hypothesis, we conducted two in vitro studies. In the first study, hydroxyapatite discs were treated with the peptides to induce AEP formation and then inoculated with S. mutans to quantify adhered bacteria, and to evaluate the total bacterial proteomes after adhesion periods of 2 h, 4 h, and 8 h. In the second study, a validated in vitro cariogenic S. mutans biofilm model was used to test the effect of DR9-DR9 and DR9-RR14 on enamel demineralization under two conditions 1) adsorbed onto the enamel surface forming the AEP, and 2) used to treat the biofilms 2x/day. Biofilms were grown for 144 h and the effect of the peptides on enamel demineralization, biomass, and total and extracellular matrix bacterial proteomes were evaluated. Results showed that DR9-DR9 reduced S. mutans adherence to HAp, but DR9-DR9 and DR9-RR14 did not have a significant effect on the development of the cariogenic biofilms formed. The engineered peptides did not modulate the bacterial proteome, neither when adhered to AEP nor when used to treat the biofilms during their formation. However, DR9-DR9 and DR9-RR14 significantly reduced enamel demineralization, suggesting that they control caries development by a physicochemical mechanism. The combinatory effect of reducing bacteria adhesion and limiting the mineral loss from the dental structure under high cariogenic challenge, suggests that the engineered peptides DR9-DR9 and DR9-RR14 represent a new translational approach for the prevention/treatment of dental caries (AU)

• FAPESP's process: 14/27034-5 - Caries susceptibility of fluorosed teeth and fluoride effect on its control: in vitro and in situ study
• Grantee: Lina María Marín Gallón
• Support Opportunities: Scholarships in Brazil - Doctorate