DISPERSION OF STREPTOCOCCUS MUTANS BIOFILMS BY A NOVEL SMALL MOLECULE

描述（由申请人提供）：龋齿是一种代价高昂的疾病，其特征是牙釉质脱矿，也被称为蛀牙。尽管科学取得了进步，但龋齿是世界上最常见的传染病，并且在幼儿中的发病率正在上升。龋齿的病原是变形链球菌。变形链球菌不仅能轻易地在牙齿表面形成生物膜，而且这种细菌还能从膳食糖中迅速产生乳酸。由于蛀牙细菌形成顽强的生物膜，对抗生素具有耐药性，因此用常规抗生素很难治疗龋齿。目前上市的疗法缺乏敏感性；它们不是种特异性的，既能杀死病原物种，也能杀死共生物种，从而防止病原生物膜的形成。为了开发一种对变形链球菌具有物种特异性的治疗剂，我们基于具有抗生物膜和抗菌特性的海绵产品bromoageliferin的结构基元构建了一个多样化的小分子文库。在之前的一项研究中，我们利用该文库进行生物膜形成抑制实验，以鉴定特异性抑制变形链球菌生物膜形成的有效小分子。目前，我们正在重新调整我们的方法，专注于分散已建立的变形链球菌生物膜。通过生物膜分散试验筛选我们的小分子文库，我们确定3F1是一种新的小分子，可以选择性地分散变形链球菌的生物膜。3F1分散了大约50%的变形链球菌生物膜，但没有分散共生物种血链球菌或戈登链球菌形成的生物膜。共聚焦激光扫描显微镜图像显示，3F1通过影响外聚基质改变了生物膜的结构，这一点通过外聚多糖的减少可以明显看出。变形链球菌分泌的糖基转移酶（Gtfs）在很大程度上负责形成外多糖，这些外多糖构成了外聚合物基质的很大一部分。3F1的活性并没有因为初级Gtf， GtfB的缺失而被否定，这使我们假设我们的小分子通过与一种潜在独特且未知的机制相互作用诱导变形杆菌生物膜的扩散，这种机制与外聚合物基质的发育和产生有关，这是生物膜成熟、结构或维持所必需的。发现与变形链球菌生物膜形成有关的新靶点可能成为预防或治疗龋齿的治疗靶点，同时维持共生种群。

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.