Gene expression and protein synthesis of esterase from Streptococcus mutans are affected by biodegradation by-product from methacrylate resin composites and adhesives

Abstract

An esterase from S. mutans UA159, SMU_118c, was shown to hydrolyze methacrylate resin-based dental monomers. Objective: To investigate the association of SMU_118c to the whole cellular hydrolytic activity of S. mutans toward polymerized resin composites, and to examine how the bacterium adapts its hydrolytic activity in response to environmental stresses triggered by the presence of a resin composites and adhesives biodegradation by-product (BBP). Materials and Methods: Biofilms of S. mutans UA159 parent wild strain, SMU_118c knockout strain (ΔSMU_118c), and SMU_118c complemented strain were incubated with photo-polymerized resin composite. High performance liquid chromatography was used to quantify the amount of a universal 2,2-Bis[4-(2-hydroxy-3-methacryloxypropoxy)phenyl]propane (bisGMA)-derived BBP, bishydroxy-propoxy-phenyl-propane (bisHPPP) in the media. Fluorescence in situ hybridization (FISH) and quantitative proteomic analysis were used to measure SMU_118c gene expression and production of SMU_118c protein, respectively, from biofilms of S. mutans UA159 wild strain that were cultured with bisHPPP. Results: The levels of bisHPPP released from composite were similar for ΔSMU_118c and media control, and these were significantly lower compared to the parent wild-strain UA159 and complemented strain (ΔSMU_118cC) (p<0.05). Gene expression of SMU_118c and productions of SMU_118c protein were higher for bisHPPP incubated biofilms (p<0.05). Significance: This study suggests that SMU_118c is a dominant esterase in S. mutans and capable of catalyzing the hydrolysis of the resinous matrix of polymerized composites and adhesives. In turn, the bacterial response to BBP was to increase the expression of the esterase gene and enhance esterase production, potentially accelerating the biodegradation of the restoration, adhesive and restoration-tooth interface, ultimately contributing to premature restoration failure.

Ageing of Dental Composites Based on Methacrylate Resins—A Critical Review of the Causes and Method of Assessment

“…Additionally, some researchers claim that unreacted monomers and composite degradation products can promote the growth of several species of cariogenic bacteria [81,82]. S. mutans is capable of catalysing the hydrolysis of the resin matrix used in dental composites and adhesives; the bacteria increase esterase production in response to degradation products, thus accelerating the biodegradation processes [83]. The formation of a dense bacterial biofilm can also result in the ongoing destruction of resin composite because of the associated changes in surface roughness and degradation by the microorganism's esterase activities [84].…”

Human neutrophils degrade methacrylate resin composites and tooth dentin

“…Nitrophenyl esters have been previously used to characterize esterases from human saliva and cariogenic dental bacteria with resin degrading properties [3,4,[6][7][8]. In the current study, human neutrophils cleaved the nitrophenyl esters and showed CE-like activity in levels relevant to intraoral degradative conditions by saliva and bacteria [3,4,6,24,28]. The data in the current study demonstrate that human neutrophils are able to significantly hydrolyze bisGMA monomers for up to 48 hours post-harvesting, corroborating the finding of previous work that has shown that CE-like activities have a high affinity for hydrolyzing this monomer [4,6].…”

Biostable, antidegradative and antimicrobial restorative systems based on host-biomaterials and microbial interactions

“…S. mutans ’ role in biodegradation was further investigated by Huang et al [51, 61, 79]. In this work, the genome of S. mutans UA159, a clinically-relevant cariogenic strain (that had its genome mapped by Ajdic et al [80]) was searched for potential esterases.…”

“…SMU_118c showed a high degree of stability by maintaining its activity for over 20 days under both neutral and under acidic cariogenic conditions, and demonstrated a very strong ability to degrade bisGMA in its monomer form as well as in commercial composite and adhesive resins. Correspondingly, specimens incubated with S. mutans UA159 wild type released large amounts of bisHPPP and showed clear signs of surface erosion after 30 days [61]. In contrast, SMU_118c knockout (KO) strain of S. mutans UA159 lost most of its degradative activity toward polymerized composites vs. the wild type.…”

“…Just as exposure to biodegradation by-products increased the expression of several virulence factors of S. mutans , exposure to bisHPPP was shown to upregulate the expression of SMU_118c in wild-type UA159 [61]. This effect is summarized in Figure 6.…”