Modulation of Streptococcus mutans Adherence to Hydroxyapatite by Engineered Salivary Peptides.

Lina Maria Marin,Walter Luiz Siqueira,Jaime Aparecido Cury,Yizhi Xiao

doi:10.3390/microorganisms10020223

Lina Maria Marin, Walter Luiz Siqueira + Show 2 more

Open Access

https://doi.org/10.3390/microorganisms10020223

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Abstract

Since the modification of the proteinaceous components of the Acquired Enamel Pellicle (AEP) could influence the adhesion of Streptococcus mutans, the most cariogenic bacteria, to dental surfaces, we assessed if engineered salivary peptides would affect the adherence and modulate the bacterial proteome upon adherence. Single-component AEPs were formed onto hydroxyapatite (HAp) discs by incubating them with statherin, histatin-3, DR9, DR9-DR9, DR9-RR14, RR14, and parotid saliva. Then, the discs were inoculated with S. mutans UA159 and the bacteria were allowed to adhere for 2 h, 4 h, and 8 h (n = 12/treatment/time point). The number of bacteria adhered to the HAp discs was determined at each time point and analyzed by two-way ANOVA and Bonferroni tests. Cell-wall proteins were extracted from adhered, planktonic, and inoculum (baseline) bacteria and proteome profiles were obtained after a bottom-up proteomics approach. The number of adhered bacteria significantly increased over time, being the mean values obtained at 8 h, from highest to lowest, as follows: DR9-RR14 > statherin > RR14 = DR9-DR9 > DR9 = histatin3 > saliva (p < 0.05). Treatments modulated the bacterial proteome upon adherence. The findings suggested a potential use of our engineered peptide DR9-DR9 to control S. mutans biofilm development by reducing bacterial colonization.

Highlights

Once exposed to saliva, dental surfaces are covered by an acellular film known as the Acquired Enamel Pellicle (AEP) [1], formed by the adsorption of specific salivary proteins and peptides [2,3,4]
Our hypothesis was that the engineered salivary peptides would reduce bacterial adherence, which was tested at a significant level α of 5%
The results of this study showed that the number of bacterial cells adhered increased over time, independently of the composition of the AEP (Table 2 and Figure 2)

Summary

Introduction

Dental surfaces are covered by an acellular film known as the Acquired Enamel Pellicle (AEP) [1], formed by the adsorption of specific salivary proteins and peptides [2,3,4]. The AEP acts as a conditioning film that influences which bacteria will first adhere to the dental surfaces [6], controlling the initial steps of biofilm formation. Different microorganism species coexist in the dental biofilm, keeping the physiological balance between health and disease. This homeostasis can be altered by certain environmental conditions in the oral cavity that favor the transition from healthy to pathogenic dental biofilms, such as the acidification of the biofilm fluid after the metabolism of dietary fermentable carbohydrates [9]. Acidic environments favor the dominance of acidogenic and aciduric bacteria such as Streptococcus mutans [10] and provoke the progressive dissolution of the mineral phase of the teeth, contributing to the development of one of the most prevalent oral diseases worldwide, namely dental caries [11]

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