Inorganic Antimicrobials in Exocrine Fluids

描述（由申请人提供）：该R21项目的目标是有助于了解次卤酸盐宿主防御因子对口腔致病菌的功效。在口腔内，次氯酸盐（OCI-）和次硫氰酸盐（OSCN-）由酶产生。然而，我们已经发现了一种简单的非酶途径，通过次氯酸（HOCI）氧化硫氰酸盐（SCN-）产生次硫氰酸盐，该反应通过将次氯酸盐的氧化当量转移到次硫氰酸盐中来保留次氯酸盐的氧化当量，次硫氰酸盐是一种对哺乳动物细胞不致命的更具鉴别力的杀生物剂。关于次卤酸盐的杀生物机制知之甚少，部分原因是它们的非凡反应性以及它们产生具有很大程度上未知的生理特性的衍生反应性中间体的级联的事实。除了动态化学的复杂性之外，生物杀灭机制的问题由于口腔的异质性而进一步复杂化，其中复杂的生物膜在化学上不同的环境中形成。最近的研究表明，E.与次氯酸盐系统相比，大肠杆菌对次氯酸盐的反应是不同的。鉴于次氯酸盐和次硫氰酸盐显然控制口腔的空间上不同的区域，但牙龈边缘附近的界面区域可能表现出这些次卤酸盐的浓度梯度，我们认为这两种杀菌剂协同作用。该项目的具体目标是：1）开发用于评估次氯酸盐和次硫氰酸盐化学系统以及选定的次级衍生物对口腔细菌库（和一些对照）的杀生物效力的方案;以及2）使用该方案和相同的口腔细菌库，研究初级和次级杀生物剂的协同效应。这些目标将通过应用全细胞化学猝灭流和相对于维斯反应器系统引入化学损伤（一些在真实的时间内产生）来实现。我们注意到，我们在这个R21应用程序中描述的所有实验都涉及到非均质培养，我们认为这是解决异质系统复杂性之前合乎逻辑的第一步。尽管如此，预计将开发的方法将适用于未来的研究，将包括混合培养物和异质系统（包括生物膜）。长期效益：了解人类防御机制控制致病性口腔微生物的能力对于改善口腔感染性疾病的治疗至关重要。我们研究的最终目标是开发特定的方法来减少致病性植物群，而不改变口腔的正常口腔（非有害）植物群。

DESCRIPTION (provided by applicant): The goal of this R21 project is to contribute to an understanding of the efficacies of hypohalite host defense factors toward pathogenic oral bacteria. Within the oral cavity, hypochlorite (OCI-) and hypothiocyanite (OSCN-) are produced by enzymes. Nevertheless, we have discovered a facile non-enzymic pathway that produces hypothiocyanite by oxidation of thiocyanate (SCN-) with hypochlorous acid (HOCI), a reaction that preserves the oxidizing equivalents of hypochlorite by transferring them to hypothiocyanite, a more discriminate biocide that is not lethal to mammalian cells. Remarkably little is known about the biocidal mechanisms of the hypohalites, due in part to their extraordinary reactivities and the fact that they produce cascades of derivative reactive intermediates with largely unknown physiologic properties. In addition to the complexities of the dynamic chemistry, the issue of biocidal mechanisms is further complicated by the heterogeneity of the oral cavity, where complex biofilms develop in chemically distinct environments. Recent studies have suggested that the genetic response of E. coli is different for the hypochlorite as compared to the hypothiocyanite system. Given that hypochlorite and hypothiocyanite apparently control spatially distinct regions of the oral cavity, but interracial regions near the gingival margin likely exhibit a concentration gradient of these hypohalites, we posit that these two biocides act in concert. The Specific Aims of this project are: 1) to develop protocols for assessing the biocidal efficacies of the hypochlorite and hypothiocyanite chemical systems and selected secondary derivatives toward a library of oral bacteria (and some controls); and 2) employing this protocol and the same library of oral bacteria, investigate synergistic effects of the primary and secondary biocides. These goals will be achieved through the application of whole-cell chemical-quench-flow and the introduction of chemical insults (some generated in real time) vis-a-vis a bioreactor system. We note that all of the experiments we describe in this R21 application involve planktonic cultures, which we believe is a logical first step before tackling the complexities of heterogeneous systems. Nevertheless, the methods that will be developed are expected to be adaptable to future studies that will include mixed-cultures and heterogeneous systems (including biofilms). Long-range Benefit: An understanding of the capacity of human defense mechanisms to control pathogenic oral microbes is essential for the improvement of therapies for oral infectious diseases. The ultimate objective of our research is the development of specific approaches to reduce pathogenic flora without altering the normal commensal (non-injurious) flora of the oral cavity.