Study on Streptococcus mutans sucrose-dependent adherence and cariogenesis.

变形链球菌蔗糖依赖性粘附和致龋的研究。

基本信息

批准号：
15592021
负责人：
OZAKI Kazumi
金额：
$ 2.11万
依托单位：
The University of Tokushima
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15592021/
关键词：
Dentinal caries Streptococcus mutans glucosyltransferase mRNA RT-PCR glucan synthesis

项目摘要

When Streptococcus mutans adheres to the surface of teeth, it begins to proliferate and form biofilm synthesizing the water-soluble (WSG) and -insoluble glucan (WIG) from sucrose. It is well known that these glucans are synthesized by three kinds of glucosyltransferases, GTFB / C / D, coded by gtfB / C / D gene, and are degraded by dextranase (DexA) coded by dexA gene. S. mutans in carious lesions may modulate glucan metabolism to adapt to the micro-environment surrounding cells. The purpose of this study was to investigate the ecological changes of S. mutans in biofilm or dentinal tubules when the environmental changes occur. We developed an in vitro artificial carious model composed of bovine dentin slices and S. mutans or deficient mutant strains. Dentin slices and S. mutans were incubated under vaious condition (temperature, pH or concentration of sucrose). The expression of gtf genes, and dexA gene were examined using PCR method. The growth rate of S. mutans MT(wild type) adhered to a dentin plate was not reduced by the environmental changes, while that of non-adhered cells decreased. The levels of gtf gene expression of adhered cells were higher than those of non-adhered cells. Moreover, gtfC gene showed the highest expression in adhered cells. TEM and LM observation revealed that S. mutans invaded most of dentinal tubules of bovine dentin in this model. When the culture condition was changed, the cells began to synthesize the intra-cellular polysaccharide. The gtfC deficient mutant strain produced lower amount of WIG that was adhered to the dentin plate compared with other gene deficient mutants. These results suggest that S. mutans adhered to the tooth surface changes the amount of GTFs and DexA, by synthesizing the glucan, or by adapting to the environmental changes.

当变形链球菌粘附在牙齿表面时，它开始增殖并形成生物膜，从蔗糖合成水溶性（WSG）和不溶性葡聚糖（WIG）。众所周知，这些葡聚糖是由gtfB/C/D基因编码的GTFB/C/D三种葡糖基转移酶合成的，并被dexA基因编码的葡聚糖酶(DexA)降解。龋齿病变中的变形链球菌可能会调节葡聚糖代谢以适应细胞周围的微环境。本研究的目的是调查环境变化时生物膜或牙本质小管中变形链球菌的生态变化。我们开发了一种由牛牙本质切片和变形链球菌或缺陷突变株组成的体外人工龋齿模型。牙本质切片和变形链球菌在各种条件（温度、pH 或蔗糖浓度）下孵育。采用PCR方法检测gtf基因和dexA基因的表达。粘附在牙本质板上的变形链球菌MT（野生型）的生长速率并未因环境变化而降低，而非粘附细胞的生长速率则下降。贴壁细胞的gtf基因表达水平高于非贴壁细胞。此外，gtfC基因在贴壁细胞中表现出最高表达。 TEM和LM观察显示，该模型中变形链球菌侵入了牛牙本质的大部分牙本质小管。当改变培养条件时，细胞开始合成胞内多糖。与其他基因缺陷突变体相比，gtfC 缺陷突变体菌株产生的附着在牙本质板上的 WIG 量较少。这些结果表明，粘附在牙齿表面的变形链球菌通过合成葡聚糖或适应环境变化，改变了 GTF 和 DexA 的量。