Acid Adaptation Targets for Eradication of Helicobacter pylori

根除幽门螺杆菌的酸适应目标

• 批准号: 8041113
• 负责人: George Sachs
• 金额: --
• 依托单位: VA GREATER LOS ANGELES HEALTHCARE SYSTEM
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-10-01 至 2014-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8041113
• 关键词: Acclimatization; Acidity; Acids; Amino Acids; Ammonia; Amoxicillin; Antibiotic Resistance; Antibiotics; Aspartate; Bacteria; Bacterial Infections; Bicarbonates; Binding; Buffers; Carbon Dioxide; Clarithromycin; Complex; Development; Down-Regulation; Drops; Enabling Factors; Ensure; Environment; Failure; Food; Gases; Gastric Juice; Gastric mucosa; Gene Cluster; Gene Targeting; Genes; Genetic Transcription; Gerbils; Glutamates; Grant; Growth; H(+)-K(+)-Exchanging ATPase; Healed; Helicobacter Infections; Helicobacter pylori; Histidine; Homology Modeling; Human; In Vitro; Infection; Investigation; Japan; Lead; Life Style; Maintenance; Measures; Medicine; Membrane; Methods; Metronidazole; Morbidity - disease rate; Mutation; Nature; Nutrient; Omeprazole; Organism; Outcome; Pathway interactions; Peptic Ulcer; Permeability; Pharmaceutical Preparations; Phase; Population; Process; Property; Protein Biosynthesis; Proteins; Regulation; Regulon; Relative (related person); Research; Resistance; Risk; Risk Factors; Role; Signal Transduction; Site; Site-Directed Mutagenesis; Small RNA; Stimulus; Stomach; Surface; System; Therapeutic; Time; Transcriptional Activation; Ulcer; United States; Up-Regulation; Urea; Urease; Veterans; base; carbonate dehydratase; cell growth; combat; drug development; extracellular; falls; healing; high risk; improved; in vivo; inhibitor/antagonist; malignant stomach neoplasm; membrane assembly; mortality; novel; pH Homeostasis; pathogen; periplasm; porin; prevent; promoter; protein-histidine kinase; protonation; response; sensor; success

DESCRIPTION (provided by applicant): Helicobacter pylori infects the stomach of half of the world's population. This infection is a primary cause of peptic ulcer disease and a high risk factor for gastric cancer. Therefore, eradication of this H. pylori infection leads to ulcer healing and lowers the risk of gastric cancer. Until the discovery of H. pylori, it was thought that stomach acid presented an inhospitable environment for bacterial infection. However, H. pylori has uniquely developed the means of surviving and growing on the acidic surface of the human stomach, a process termed acid acclimation. Disruption of this process leads to loss of survival in acid, therefore the components of this process would provide novel targets for eradication therapy. Current eradication therapies require the use of antibiotics along with acid inhibitory drugs. The successful eradication by these therapies is decreasing due to increasing antibiotic resistance, resulting in a response rate of < 80% in the USA. Acid acclimation is the ability of the organism to maintain a neutral periplasmic pH homeostasis in the presence of acid to allow gastric infection. Bacteria sense and respond to environmental stimuli via two component histidine kinase signaling systems. In the case of H. pylori, environmental acidification sensing is initiated through the HP0165/HP0166 two component system. Accordingly, the first hypothesis to be explored is that graded responses to acidity are regulated by this HP0165/HP0166 two component system. The system responds by acid-induced transcriptional upregulation of two promoters in the urease gene cluster, pureA and pureI, acid-induced post-translational upregulation of assembly UreI with apourease and the urease accessory proteins required for Ni2+ insertion along with Ni2+ entry, and also post-transcriptional down regulation by sRNAs at neutral pH. The UreI/urease membrane assembly is essential for acid acclimation and acid survival of the organism, and an understanding of the assembly mechanism is required for targeted therapy to this process. Therefore, the role of the HP0165/HP0166 TCS in membrane recruitment, assembly and activation of urease, in regulation of sRNA control of urease expression, and pH sensing by the TCS will be explored. The growth dependent antibiotics clarithromycin or amoxicillin are not effective unless bacteria are in growth phase. Improving acid inhibition should improve therapeutic outcome. In the second aim, we hypothesize that inhibition of acid secretion increases the number of bacteria in growth phase, making them sensitive to growth dependent antibiotics necessitating the requirement for administration of acid inhibitory compounds, in addition to antibiotics for successful eradication. The finding that slow omeprazole metabolizers respond with much improved acid control and effective eradication with omeprazole and amoxicillin alone, suggests that improved acid inhibition increases the sensitivity of the organism to growth dependent antibiotics. From this it follows that, with more consistent and greater elevation of intragastric pH, more organisms are in the antibiotic sensitive growth phase rather than the resistant stationary phase. Maintenance of an elevated pH for both day and night should put almost all H. pylori in growth phase. Therefore, the effect of acid inhibition on the rate of H. pylori protein synthesis as an indicator of bacterial cell growth will be measured in vitro and in vivo. PUBLIC HEALTH RELEVANCE: H. pylori infection has a causal role in peptic ulcer disease and increases the risk of gastric cancer. Peptic ulcer disease and gastric cancer are major causes of morbidity in the Veterans population, in the United States and worldwide. H. pylori inhabits the stomach and has evolved unique acid response mechanisms to allow gastric colonization. Standard triple or quadruple therapies with acid blocking medicines and antibiotics have become less effective, falling below 80% success rate due to increasing antibiotic resistance. An understanding of how H. pylori colonizes the stomach will aid the development of novel eradication therapies. A possible strategy to replace current therapy is to target genes that allow the bacteria to survive in acid with non-antibiotic compounds. Another possible strategy is to improve control of the pH of the bacterial environment, so that dual therapy with acid inhibition and amoxicillin could be used. This would involve development of drugs with better acid blocking properties.

描述（由申请人提供）： 幽门螺杆菌感染了世界上一半人口的胃。这种感染是消化性溃疡病的主要原因，也是胃癌的高危因素。因此，根除幽门螺杆菌感染可以促进溃疡愈合并降低患胃癌的风险。在发现幽门螺杆菌之前，人们一直认为胃酸为细菌感染提供了一个不适宜的环境。然而，幽门螺杆菌独特地发展了在人胃的酸性表面上生存和生长的方法，这一过程被称为酸适应。该过程的破坏会导致在酸中存活的丧失，因此该过程的组成部分将为根除治疗提供新的靶标。目前的根除疗法需要使用抗生素和抑酸药物。由于抗生素耐药性增加，这些疗法的成功根除率正在下降，导致美国的缓解率低于 80%。 酸适应是生物体在酸存在下维持中性周质 pH 稳态以允许胃感染的能力。细菌通过两个组成部分的组氨酸激酶信号系统来感知和响应环境刺激。对于幽门螺杆菌，环境酸化感测是通过 HP0165/HP0166 两组分系统启动的。因此，要探讨的第一个假设是，对酸度的分级反应是由 HP0165/HP0166 两组分系统调节的。该系统通过酸诱导脲酶基因簇中两个启动子（pureA 和 pureI）转录上调，酸诱导翻译后上调组装 UreI 与 apourease 以及 Ni2+ 插入和 Ni2+ 进入所需的脲酶辅助蛋白，以及中性 pH 值下 sRNA 的转录后下调。 UreI/脲酶膜组装对于生物体的酸适应和酸生存至关重要，并且需要了解组装机制以针对该过程进行靶向治疗。因此，将探讨 HP0165/HP0166 TCS 在脲酶的膜募集、组装和激活、脲酶表达的 sRNA 控制调节以及 TCS 的 pH 感测中的作用。 除非细菌处于生长期，否则生长依赖性抗生素克拉霉素或阿莫西林无效。改善酸抑制应该改善治疗效果。在第二个目标中，我们假设抑制酸分泌会增加生长期的细菌数量，使它们对生长依赖性抗生素敏感，因此除了成功根除抗生素外，还需要施用酸抑制化合物。研究发现，奥美拉唑缓慢代谢者单独使用奥美拉唑和阿莫西林可显着改善酸控制和有效根除，这表明改善的酸抑制会增加生物体对生长依赖性抗生素的敏感性。由此可见，随着胃内 pH 值更加一致和更大的升高，更多的生物体处于抗生素敏感生长期而不是耐药静止期。白天和晚上保持较高的 pH 值将使几乎所有幽门螺杆菌都处于生长期。因此，将在体外和体内测量酸抑制对作为细菌细胞生长指标的幽门螺杆菌蛋白质合成速率的影响。 公共卫生相关性： 幽门螺杆菌感染与消化性溃疡病有关，并增加患胃癌的风险。消化性溃疡病和胃癌是美国和全世界退伍军人发病的主要原因。幽门螺杆菌栖息在胃中，并进化出独特的酸反应机制以允许胃定植。由于抗生素耐药性增加，采用酸阻滞药物和抗生素的标准三联或四联疗法已变得不太有效，成功率降至 80% 以下。了解幽门螺杆菌如何在胃中定殖将有助于开发新型根除疗法。替代当前疗法的一种可能策略是使用非抗生素化合物来靶向允许细菌在酸中生存的基因。另一种可能的策略是改善对细菌环境pH值的控制，以便可以使用酸抑制和阿莫西林的双重治疗。这将涉及开发具有更好的酸阻断特性的药物。