DISPERSION OF STREPTOCOCCUS MUTANS BIOFILMS BY A NOVEL SMALL MOLECULE

描述(申请人提供)：龋齿是一种代价高昂的疾病，其特征是牙釉质脱矿，也称为龋齿。尽管科学取得了进步，但龋齿仍是世界上最常见的传染病，而且在幼儿中的发病率正在上升。龋病的病原菌为变形链球菌。变形链球菌不仅可以很容易地在牙齿表面形成生物膜，而且这种细菌还能迅速从饮食中的糖中产生乳酸。龋齿很难用传统的抗生素治疗，因为致龋菌形成了坚韧的生物膜，这些生物膜对抗生素有抗药性。目前市场上销售的治疗方法缺乏敏感性；它们不是针对特定物种的，它们会杀死致病物种和共生物种，这些物种可以防止形成致病生物膜。为了开发一种对变形链球菌具有物种特异性的治疗剂，我们根据具有抗生物被膜和抗菌特性的海绵产品溴沉淀素的结构基序，构建了一个多样化的小分子文库。在之前的研究中，我们利用该文库进行了生物被膜形成抑制试验，以确定特异性地抑制变形链球菌生物被膜形成的有效小分子。目前，我们正在调整我们的方法，将重点放在分散已建立的变形链球菌生物膜上。通过生物膜分散实验筛选我们的小分子文库，我们确定3F1是一个选择性地分散变形链球菌生物膜的新的小分子。3F1能分散约50%的变形链球菌生物膜，但不能分散共生种血链球菌和戈登链球菌所形成的生物膜。激光共聚焦扫描显微镜图像显示，3F1通过影响胞外聚合物基质改变了生物膜的结构，这一点通过胞外多糖量的减少而变得明显。变形链球菌分泌的葡萄糖转移酶(GTFS)主要负责胞外多糖的形成，胞外多糖占胞外多聚基质的很大比例。3F1的活性并没有因为缺乏主要的GTF，GTFB而被否定，这导致我们假设我们的小分子通过与一种潜在的独特和未知的机制相互作用来诱导变形链球菌生物膜的扩散，这种机制与胞外多聚体基质的发展和产生有关，这是生物膜成熟、结构或维持所必需的。一个与变形链球菌生物膜形成有关的新靶点的发现可能成为预防或治疗龋病的治疗靶点，同时保持共生种群。

DESCRIPTION (provided by applicant): Dental caries is a costly disease characterized by the demineralization of the enamel, otherwise known as tooth decay. Despite advances in science, dental caries is the most common infectious disease worldwide and is increasing in incidence among young children. The etiologic causative agent of dental caries is Streptococcus mutans. Not only can S. mutans form biofilms readily on the tooth surface, but this bacterium rapidly produces lactic acid from dietary sugars. Dental caries cannot be easily treated with conventional antibiotics as cariogenic bacteria form tenacious biofilms, which are resistant to antibiotics. Current marketed therapies lack sensitivity; they are not species-specific and kill pathogenic species as well as commensal species, which are protective against the formation of pathogenic biofilms. In order to develop a therapeutic agent that is species specific for S. mutans, we constructed a diverse library of small molecules based on the structural motifs of bromoageliferin, a marine sponge product with antibiofilm and antibacterial properties. In a previous study, we utilized the library in a biofilm formation inhibition assay to identify potent small molecules that inhibit S. mutans biofilm formation specifically. Currently, we are redirecting our approach to focus on dispersing established S. mutans biofilms. By screening our library of small molecules with a biofilm dispersion assay, we identified 3F1 as a novel small molecule that selectively disperses S. mutans biofilms. While 3F1 dispersed approximately 50% of S. mutans biofilm, it did not disperse biofilms formed by commensal species Streptococcus sanguinis or Streptococcus gordonii. Confocal laser scanning microscopy images revealed that 3F1 altered the architecture of the biofilm by affecting the exopolymeric matrix, made evident through the reduced amount of exopolysaccharides. Glucosyltransferases (Gtfs) secreted by S. mutans are largely responsible for forming the exopolysaccharides which make up a large proportion of the exopolymeric matrix. The activity of 3F1 was not negated by the absence of the primary Gtf, GtfB, leading us to hypothesize that our small molecule induces the dispersal of S. mutans biofilms by interacting with a potentially unique and unknown mechanism related to the development and production of the exopolymeric matrix, which is necessary for biofilm maturation, structure, or maintenance. The identification of a novel target implicated in biofilm formation in S. mutans could potentially become a therapeutic target for the prevention or treatment of dental caries, while maintaining the commensal populations.