TLR5 Antagonists for Infectious Disease Therapy

描述(申请人提供)：在各种类型的人类细胞上发现的一系列保守的Toll样受体(TLRs)在识别入侵病原体和建立有效的炎症免疫反应方面发挥着重要作用。每个受体都与特定的微生物配体结合，并触发一条信号转导途径，导致编码促炎细胞因子、趋化因子和各种天然宿主防御分子的基因转录。TLRs的激活对于动员先天免疫反应至关重要，先天免疫反应是人类宿主在许多细菌感染期间的早期保护机制。然而，令人惊讶的是，同样的信号通路可能对宿主有害，并加剧感染，通过引发过度和破坏性的炎症而导致广泛的组织破坏和细菌传播。在某些急性和慢性感染中会出现这种情况，包括囊性纤维化中的铜绿假单胞菌和洋葱伯克霍尔德氏菌感染，以及肺炎和败血症中的铜绿假单胞菌和假鼻疽杆菌感染。其中一种这样的TLR配体是鞭毛蛋白，它是细菌鞭毛运动装置的一种成分，由TLR5识别。在初步研究中，鞭毛蛋白-TLR5的相互作用被证明是铜绿假单胞菌毒力、存活和在小鼠肺炎模型中传播的主要原因。这项研究的总体目标是开发治疗药物，对抗TLR5和鞭毛蛋白相互作用所产生的促炎信号通路。在第一阶段，将应用灵敏的全细胞分析来筛选鞭毛蛋白/TLR5相互作用拮抗剂的化合物文库。在高通量筛选中确认命中后，活性化合物将在二次检测中进行表征，以确定那些无毒的和专门干扰鞭毛蛋白-TLR5信号通路的化合物。最有效、最特异的抑制剂将在铜绿假单胞菌感染模型中进行测试，在该模型中，肺部定植和扩散到器官依赖于这种微生物鞭毛蛋白的表达。这一第一阶段项目的结果将为开发治疗药物提供体内验证的TLR5拮抗剂，以降低细菌败血症和慢性感染的发病率和死亡率。

DESCRIPTION (provided by applicant): A family of conserved toll-like receptors (TLRs) found on a variety of human cell types plays an important role in recognition of invading pathogens and in mounting an effective inflammatory immune response. Each these receptors binds a specific microbial ligand and triggers a signal transduction pathway leading to transcription of genes encoding pro-inflammatory cytokines, chemokines and variety of innate host-defense molecules . Activation of TLRs is critical for mobilization of the innate immune response, an early acting protective mechanism for the human host during many bacterial infections. Surprisingly, however, the same signaling pathways can be detrimental to the host and exacerbate the infection, causing extensive tissue destruction and bacterial dissemination by provoking excessive and damaging inflammation. This occurs in certain acute and chronic infections, including Pseudomonas aeruginosa and Burkholderia cepacia infections in cystic fibrosis as well as P. aeruginosa and B. pseudomallei infections in pneumonia and septicemia. One such TLR ligand is flagellin, a component of the bacterial flagellar motility apparatus, which is recognized by TLR5. In preliminary studies, this flagellin-TLR5 interaction was shown to be the major cause of Pseudomonas aeruginosa virulence, survival, and dissemination in a mouse pneumonia model. The overall objective of this research is to develop therapeutic agents that antagonize the pro-inflammatory signaling pathways resulting from the interaction between TLR5 and flagellin. In Phase I, a sensitive whole-cell assay will be applied to screen libraries of compounds for antagonists of flagellin/TLR5 interaction. Following confirmation of the hits from the high throughput screen, the active compounds will be characterized in secondary assays to identify those which are non-toxic and which specifically interfere with the flagellin-TLR5 signaling pathway. The most potent, specific, inhibitors will be tested in a P. aeruginosa infection model, in which lung colonization and dissemination into organs depends on the expression of flagellin by this organism. The results of this Phase I project will provide in vivo validated TLR5 antagonists for the development of therapeutics to reduce morbidity and mortality in bacterial sepsis and chronic infections.