Inhibition of Streptococcus mutans by oral commensal streptococci and nitrie-mediated activity

项目总结/摘要 变形链球菌是龋病的主要病原体，龋病是最常见的感染性疾病 世界范围内。致龋菌S.变链菌在牙本质损害的发病机制中起着重要作用。 龋齿预防或成功治疗严重龋齿仍然是一项难以捉摸的任务。常规治疗 对于龋齿，通常涉及牙齿生物膜的机械去除、抗生素的使用或侵入性的治疗。 程序.然而，这些治疗有时是无效的，使用抗生素或侵入性 手术可能导致产生耐药性病原体或并发症。所以一间 需要另一种侵入性较小的方法。有趣的是，口腔显示出更高浓度的 亚硝酸盐比其他身体部位。口腔中亚硝酸盐浓度升高与 减少龋齿的患病率，表明亚硝酸盐可能是治疗的替代疗法 龋齿。然而，亚硝酸盐如何干扰生物膜形成的确切机制， 致病性S.变种人未知口腔内有数百种细菌， 它们相互作用并有助于口腔的健康和疾病状态。我们的初步数据 证明产生过氧化氢的口腔链球菌副血链球菌抑制S. 变形菌生长和生物膜形成的亚硝酸盐的存在下，揭示了一种新的抗感染策略， 口腔溃疡。为了开发含亚硝酸盐的治疗剂来治疗龋齿， 关键是要了解S.变形菌亚硝酸盐抗性。转座子诱变S.变形 鉴定了对S.副血吸虫和亚硝酸盐介导的活性。一个突变体被映射到 编码组氨酸激酶（SMU.486）的基因。这种组氨酸激酶及其反应调节剂（SMU.487） 与大肠杆菌中的亚硝酸盐敏感双组分调节系统同源，这表明它们 可能介导S.变形链球菌S.副血吸虫和亚硝酸盐。因此，这一行动的直接目标 研究方案是研究亚硝酸盐传感双组分体系SMU.486和SMU.487 介体S.变形杆菌对亚硝化应激的反应，并确定亚硝化应激反应途径控制 SMU.486和SMU.487。RNA测序/转录组学将用于分析SMU.486和 SMU.487有助于抗亚硝化胁迫。此外，该提案还将考察S. 和亚硝酸盐介导的抑制S.在牙科动物模型中， 龋齿在此期间，候选人将完成口腔微生物学，RNA 测序/转录组学和其他专业发展活动。指导培训将为 独立R 00阶段的候选者，其中候选者将确定S的适用性。 除了继续表征其它转座子突变体外， 赋予对S.副血吸虫和亚硝酸盐介导的活性。伯明翰亚拉巴马大学 为候选人提供了一个特殊的环境，以接受指导培训并完成概述的 由于合作研究环境和最先进的设施，研究。

Project Summary/Abstract Streptococcus mutans is the major etiological agent of dental caries, the most prevalent infectious disease world-wide. Biofilm formation by the cariogenic bacterium S. mutans is crucial for the pathogenesis of dental caries. Preventing or successfully treating severe caries remains an elusive task. The conventional treatment for dental caries usually involves the mechanical removal of dental biofilms, the use of antibiotics, or invasive procedures. However, these treatments are sometimes ineffective and the use of antibiotics or invasive procedures can result in the development of drug resistant pathogens or complications. Therefore, an alternative and less invasive approach is needed. Interestingly, the oral cavity exhibits higher concentrations of nitrite than other body sites. Elevated concentrations of nitrite in the oral cavity have been associated with a reduced prevalence of dental caries, suggesting that nitrite may be an alternative therapeutic for the treatment of caries. However, the exact mechanism(s) of how nitrite interferes with the biofilm formation and pathogenesis of S. mutans is unknown. The oral cavity harbors hundreds of bacterial species and they interact with each other and contribute to health and disease status of the oral cavity. Our preliminary data demonstrate that the hydrogen peroxide-producing oral commensal Streptococcus parasanguinis, inhibits S. mutans growth and biofilm formation in the presence of nitrite, revealing a new anti-infection strategy by the commensal oral streptococcus. In order to develop nitrite-containing therapeutics to treat dental caries, it is critical to understand mechanisms of S. mutans nitrite resistance. Transposon mutagenesis of S. mutans identified mutants that are resistant to S. parasanguinis and nitrite-mediated activity. One mutant is mapped to a gene coding for a histidine kinase (SMU.486). This histidine kinase and its response regulator (SMU.487) are homologous to a nitrite sensing two-component regulatory system in Escherichia coli, suggesting that they may mediate inhibition of S. mutans by S. parasanguinis and nitrite. Therefore, the immediate goal of this research proposal is to investigate how the nitrite sensing two-component system SMU.486 and SMU.487 mediate S. mutans’ response to nitrosative stress and identify nitrosative stress response pathways controlled by SMU.486 and SMU.487. RNA-sequencing/transcriptomics will be used to analyze how SMU.486 and SMU.487 contribute to nitrosative stress resistance. In addition, the proposal will examine the ability of S. parasanguinis and nitrite-mediated activity to inhibit S. mutans and prevent caries in an animal model of dental caries. During this time the candidate will complete mentored training in Oral Microbiology, RNA sequencing/transcriptomics, and other professional development activities. The mentored training will prepare the candidate for the independent R00 phase in which the candidate will determine the suitability of S. parasanguinis as a probiotic in addition to continuing the characterization of other transposon mutants that confer resistance to S. parasanguinis and nitrite-mediated activity. The University of Alabama at Birmingham provides an exceptional environment for the candidate to receive mentored training and complete the outlined research due to the collaborative research environment, and state of the art facilities.