Helicobacter pylori: Tactic Responses and Persistence in the Gastric Mucosa

幽门螺杆菌：胃粘膜中的策略反应和持久性

• 批准号: 7264446
• 负责人: PAUL Stokes HOFFMAN
• 金额: $ 30.64万
• 依托单位: UNIVERSITY OF VIRGINIA
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-03-01 至 2012-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7264446
• 关键词: Acidity; Acids; Address; Affect; Agar; Amino Acids; Bacteria; Behavior; Bile Acids; Biological; Biological Assay; Biological Models; Blood capillaries; Campylobacter jejuni; Chemoreceptors; Chemotaxis; Classification; Count; Cytoplasm; Development; Electron Microscopy; Epithelial Cells; Epithelium; Evolution; Fluorescent Dyes; Gastric mucosa; Gastric ulcer; Gastritis; Gastrointestinal tract structure; Gene Expression; Genes; Genetic; Helicobacter; Helicobacter hepaticus; Helicobacter pylori; Histidine; Human; Hydrochloric Acid; Immunoblotting; Infection; Interleukin-12; Intestines; Knowledge; Lead; Life; Ligand Binding; Link; Maintenance; Malignant Neoplasms; Microbe; Molecular; Monitor; Mucous body substance; Mus; Orthologous Gene; Pathogenesis; Physiologic pulse; Population; Process; Proteome; Proton-Motive Force; Pulse taking; Pylorus; Radiolabeled; Range; Relative (related person); Research; Research Personnel; Role; Scanning; Score; Screening procedure; Signal Transduction; Site; Site-Directed Mutagenesis; Southern Blotting; Stomach; System; Testing; Thick; Tube; Urea; Urease; Vaccines; Video Microscopy; acid stress; base; biological adaptation to stress; blind; capillary; cell motility; deletion analysis; insight; malignant stomach neoplasm; microbial; mucosa-associated lymphoid tissue lymphoma; mutant; novel; novel therapeutics; pathogen; periplasm; programs; promoter; protonation; radiotracer; receptor; response; trait; vector

DESCRIPTION (provided by applicant): Mucosal pathogens of the gastrointestinal tract must penetrate layers of mucus in order to establish infection of the underlying mucosal epithelium. The fundamental biological question our research addresses is whether mucosal colonization is by random chance or a function of genetic traits that direct the process. We are using the human gastric pathogen Helicobacter pylori as a model system to study mucosal colonization. We hypothesize that H. pylori responds rapidly to changes in local acidity in gastric mucus, through motility-linked chemoreceptors, that monitor temporal changes in gastric acidity; and (ii) that acid pH taxis is essential for primary colonization and for persistence by enabling bacteria to escape extreme acid stress. To test this hypothesis we have developed several pH taxis assays in which H. pylori displays negative chemotactic responses to acids (not to bases) and in these assays non-gastric species H. hepaticus and Campylobacter jejuni are not pH tactic. We determined that novel chemoreceptor TIpB is required for both pH taxis and for gastric colonization. We propose the following specific aims to further test the pH taxis hypothesis: (Aim I) To isolate TIpB function by deletion of the three other chemoreceptor genes to validate TIpB function, determine acid thresholds and the relative abundance of TIpB and other Tips and by screening gastric and non-gastric species of Helicobacter to determine whether TIpB and acid sensing are unique to gastric species; (Aim II) TIpB contains unique periplasmic and HAMP domains that might participate in acid sensing and both deletion and site directed mutagenesis scanning will be used to identify which domains sense acid (periplasmic or cytoplasmic) and whether protonation of key histidine or other amino acids is required for signal transduction; (Aim III) We propose to determine how the urease system (pH stasis) and global response regulators ArsRS and HP1043 (acid stress) interface with rapid acid pH tactic behavior in directing acid survival, gastric colonization and life long persistence. Relevance: It is remarkable that H. pylori can survive and display acid pH taxis in 100 mM hydrochloric acid, a feat unmatched by any microbial pathogen studied to date. Understanding the fundamental mechanisms associated with acid survival and gastric colonization underpins all eradicative strategies from vaccines to novel therapeutics against a pathogen that infects half of the world's population.

描述（由申请人提供）：胃肠道粘膜病原体必须穿透粘液层才能感染下面的粘膜上皮。我们研究解决的基本生物学问题是粘膜定植是随机的还是指导该过程的遗传特征的函数。我们使用人类胃病原体幽门螺杆菌作为模型系统来研究粘膜定植。我们假设幽门螺杆菌通过与运动相关的化学感受器对胃粘液局部酸度的变化做出快速反应，从而监测胃酸度的暂时变化； (ii) 酸性 pH 值对于初级定殖和持续存在至关重要，因为它使细菌能够逃避极端的酸胁迫。为了检验这一假设，我们开发了几种 pH 趋化分析，其中幽门螺杆菌对酸（而不是碱）表现出负趋化反应，并且在这些分析中，非胃物种肝幽门螺杆菌和空肠弯曲杆菌不具有 pH 趋化反应。我们确定新型化学感受器 TIpB 是 pH 趋向性和胃定植所必需的。我们提出以下具体目标来进一步检验 pH 趋向性假说：（目的 I）通过删除其他三个化学感受器基因来验证 TIpB 功能，确定 TIpB 和其他提示的酸阈值和相对丰度，并通过筛选胃和非胃螺杆菌物种来确定 TIpB 和酸感应是否为胃物种所独有，从而分离 TIpB 功能； （目标 II）TIpB 包含可能参与酸感应的独特周质和 HAMP 结构域，并且将使用缺失和定点诱变扫描来识别哪些结构域感应酸（周质或细胞质）以及信号转导是否需要关键组氨酸或其他氨基酸的质子化； （目标 III）我们建议确定脲酶系统（pH 停滞）和全局响应调节剂 ArsRS 和 HP1043（酸应激）如何与快速酸性 pH 策略行为相互作用，以指导酸存活、胃定植和终生持久性。相关性：值得注意的是，幽门螺杆菌可以在 100 mM 盐酸中存活并表现出酸性 pH 值，这是迄今为止研究的任何微生物病原体都无法比拟的壮举。了解与胃酸存活和胃定植相关的基本机制是从疫苗到针对感染世界一半人口的病原体的新型疗法的所有根除策略的基础。