S. mutans GTF - a novel target for dental caries prevention

 描述（由申请人提供）：龋齿被认为是美国的一个主要健康问题。因此，开发预防和控制龋齿的药物现在是美国牙科的“咒语”。多年来，氟化物已被用于社区供水和牙膏中，以控制龋齿。虽然这些预防措施在一定程度上是成功的，但并不能完全防止龋齿的形成。因此，需要新的创新方法来防治龋齿。虽然大量的口腔细菌与龋齿有关，但变形链球菌已被认为是龋齿发生和发展的主要病原体。一个S。变形杆菌毒力因子归因于其致龋特性是其表达胞外葡萄糖基 转移酶（GTF）。在大多数链球菌菌株中发现三种表达GTF活性的不同gtf基因。变异人基因gtfB和gtfC分别表达GTF-I和GTF-SI酶，其主要合成水不溶性葡聚糖，并且gtfD编码GTF-S，其是一种合成水溶性葡聚糖的酶。葡聚糖有助于生物膜的结构完整性，并使生长的细菌牢固地粘附在牙齿表面。S.与亲本S相比，基因（gtfB-和gtfC-）中的一个或两个缺陷的变形杆菌表现出显著降低的光滑表面龋损伤水平。变异人在我们自己的研究中，我们已经证明gtfB基因敲除的S.与野生型相比，变异株显示其形成生物膜的能力降低80%。因此，S.变形杆菌GTF对于葡聚糖合成、生物膜形成和由此产生的龋齿形成是必需的。因此，我们建议抑制S。作为一种新的策略，以防止葡聚糖形成和致龋生物膜的变形GTF。与传统的抗生素不同，变形链球菌GTF抑制剂将选择性地抑制致龋生物膜，而不影响口腔细菌植物群。我们利用最近公布的GTF-SI的X射线晶体结构， GTF抑制剂的设计。在计算机筛选和SAR研究的帮助下，我们已经确定了S.变异人这些化合物选择性地抑制S.在低微摩尔浓度下的变形链球菌生物膜，而不影响S.变形菌或其它口腔细菌。对GTF无活性的我们的先导化合物的结构相似的类似物也被发现对生物膜无活性，这表明这些作用 是直接相关的。该提议的目标是优化莱亚化合物的抗生物膜活性，并建立其作为治疗致龋生物膜和龋齿的药剂的潜力。具体目的是：目的1：通过构效关系研究优化先导化合物的生物膜抑制活性。目的2：评价其体外活性 所述化合物，并确定1或2种优化的先导化合物在龋齿大鼠模型中的功效。

 DESCRIPTION (provided by applicant): Dental caries is considered to be a major health concern in the United States. Accordingly, developing drugs to prevent and control dental caries is now the `mantra' in American Dentistry. Fluoride has been used in community water supplies and toothpastes to control dental caries over the years. Though these preventive measures are successful to some extent, it does not prevent caries formation completely. Thus, new innovative approaches are necessary to combat dental caries. Although a large number of oral bacteria have been associated with dental caries, Streptococcus mutans has been implicated as the major etiological agent in the initiation and development of dental caries. One of S. mutans virulence factors attributed to its cariogenic property is its expression of extracellular glucosyl transferases (GTFs). Three distinct gtf genes expressing GTF activity are found in most strains of S. mutans. Genes gtfB and gtfC express GTF-I and GTF-SI enzymes respectively, which synthesize predominantly water- insoluble glucans and gtfD, encodes for GTF-S, an enzyme that synthesizes water-soluble glucans. Glucans contribute to the structural integrity of biofilms and provide firm adherence of growing bacteria to tooth surfaces. S. mutans defective in either or both of genes (gtfB- and gtfC-) exhibited markedly reduced levels of smooth surface caries lesion as compared to the parental S. mutans. In our own studies, we have shown that the gtfB- knockout S. mutans exhibited 80% reduction in its ability to form biofilm as compared to the wild type. Thus, functions of S. mutans GTFs are essential for glucan synthesis, biofilm formation and resulting cariogenesis. Therefore, we propose inhibition of S. mutans GTFs as a novel strategy to prevent the glucan formation and cariogenic biofilms. Unlike traditional antibiotics, S mutans GTF inhibitors will selectively inhibit cariogenic biofilms without affecting commensal oral bacterial flora. We have utilized the recently published X-ray crystal structure of GTF-SI for the design of GTF inhibitors. With the help of in-silico screening and SAR studies, we have identified low micromolar inhibitors of GTFs of S. mutans. These compounds selectively inhibit S. mutans biofilms at low micromolar concentrations without affecting the growth of S. mutans or other oral commensal bacteria. Structurally similar analogs of our lead compounds that were inactive against GTFs were also found to be inactive against biofilm, indicating that these effects are directly related. The goal of this proposal is to optimize the anti-biofilm activity of the lea compounds and to establish their potential as agents to treat cariogenic biofilms and dental caries. The specific aims are: Aim 1: To optimize the biofilm inhibitory activity of the lead compounds by structure activity relationship studies. Aim 2: To evaluate the in vitro activities of the compounds and to determine the efficacy of 1 or 2 optimized lead compounds in a rat model of dental caries.