Deciphering Helicobacter pylori's glycocode: uncovering & harnessing drug targets

描述(申请人提供)：幽门螺杆菌(HP)是全球十二指肠溃疡和胃炎的主要原因。不幸的是，现有的抗生素往往无法根除幽门螺杆菌感染并治愈这些疾病。对幽门螺杆菌发病机制的深入了解将极大地帮助开发新的治疗方法。幽门螺杆菌的毒力似乎与病原体糖基化蛋白质的能力直接相关。虽然幽门螺杆菌合成了大量的糖蛋白，但尚不清楚这些物种中的哪些参与了宿主与病原体的相互作用，如何利用它们来治疗慢性幽门螺杆菌感染，以及它们是否可以选择性地作为靶点。该项目的长期目标是利用化学的力量来进行细菌糖基化的基础研究，特别是与人类疾病有关的基础研究。本应用程序的目的是识别可用作药物靶点的Hp糖蛋白，根据Hp独特的多糖开发一种灭活Hp的策略，并评估我们针对Hp的靶向策略相对于其他细菌的选择性。中心假说 应用的重点是幽门螺杆菌的糖蛋白参与宿主和病原体的相互作用，可以作为共价传递治疗药物的靶点，并且可以在不广泛干扰大多数细菌的情况下选择性地靶向。我们的假设是基于我的实验室提供的强大的初步数据，包括证明在宿主细胞存在的情况下，幽门螺杆菌表面糖蛋白的子集过度表达。此外，我的实验室报告说，治疗性探针可以共价输送到HP表面的糖链上。最后，我的实验室已经证明，多糖的代谢标记在细菌物种中并不统一，从而为选择性靶向只在病原体上发现的多糖奠定了基础。这项拟议研究的基本原理是，治疗干预的新靶点将被揭示，从而产生治疗细菌性疾病的新的创新方法。在强大的初步数据的指导下，这一假设将通过追求三个具体目标来检验：1)识别参与宿主-病原体相互作用的HP糖蛋白；2)开发针对HP表面多糖的治疗药物；以及3)评估我们针对HP的靶向策略的选择性。在第一个目标下，幽门螺杆菌的糖蛋白在与宿主细胞结合中的重要性 将被评估，一个已经被证明的方法将被用来识别在宿主细胞存在的情况下优先过度表达的HP糖蛋白。在第二个目标下，幽门螺杆菌表面的代谢标记的多糖将被治疗药物靶向，然后将测量对幽门螺杆菌的损害。在第三个目标下，将评估叠氮糖在病原菌和共生菌表面的掺入，并将分析共价治疗药物靶向HP的选择性。这项拟议的研究具有创新性，因为它将导致一种有针对性的抗菌策略，该策略有可能治疗HP感染，同时将对其他细菌的影响降至最低，这与现状有实质性的不同。这一贡献意义重大，因为它是一系列研究中的重要一步，有望导致开发基于糖基化的治疗溃疡和胃炎的策略。

DESCRIPTION (provided by applicant): Helicobacter pylori (Hp) is the leading cause of duodenal ulcers and gastritis worldwide. Unfortunately, existing antibiotics frequently fail to eradicate Hp infection and cure these ailments. The development of new treatments will be greatly aided by insights into the pathogenesis of Hp. Virulence of Hp appears to be directly linked to the pathogen's ability to glycosylate proteins. Although Hp synthesizes a vast array of glycoproteins, what is not clear is which of these species are involved in host-pathogen interactions, how they can be harnessed to treat chronic Hp infection, and if they can be targeted selectively. The long-term goal of this project is to harness the power of chemistry to enable fundamental studies of bacterial glycosylation, particularly with respect to human disease. The objectives of this application are to identify Hp glycoproteins that could serve as drug targets, to develop a strategy to inactivate Hp based on its distinctive glycans, and to assess the selectivity of our targeting strategy for Hp over other bacteria. The central hypothesis of the application is that Hp's glycoproteins are involved in host-pathogen interactions, can serve as targets for covalent delivery of therapeutics, and can be selectively targeted without broadly interfering with most bacteria. Our hypothesis has been formulated on the basis of strong preliminary data produced in my laboratory, including the demonstration that a subset of Hp's surface glycoproteins are overexpressed in the presence of host cells. Further, my laboratory has reported that therapeutic probes can be covalently delivered to surface glycans on Hp. Finally, my lab has demonstrated that metabolic labeling of glycans is not uniform across bacterial species, thus setting the stage for selective targeting of glycans only found on pathogens. The rationale for the proposed research is that novel targets of therapeutic intervention will be revealed, resulting in new and innovative approaches to treat bac- terial disease. Guided by strong preliminary data, this hypothesis will be tested by pursuing three specific aims: 1) Identify Hp glycoproteins involved in host-pathogen interactions; 2) Develop therapeutics that target Hp's surface glycans; and 3) Assess the selectivity of our targeting strategy for Hp. Under the first aim, the importance of Hp's glycoproteins in binding to host cells will be evaluated, and an already proven approach will be used to identify Hp glycoproteins that are preferentially overexpressed in the presence of host cells. Under the second aim, metabolically labeled glycans on Hp's surface will be targeted with therapeutics, and then the damage to Hp will be measured. Under the third aim, the incorporation of azidosugars onto surfaces of pathogenic and symbiotic bacteria will be evaluated, and the selectivity of targeting Hp with covalent therapeutics will be analyzed. The proposed research is innovative because it will lead to a targeted antibacterial strategy that has the potential to treat Hp infection while minimizing the effects on other bacteria, a substantive departure from the status quo. This contribution is significant because it is an important step in a continuum of research that is expected to lead to development of glycosylation-based strategies to treat ulcers and gastritis.