Novel antimicrobial agents for bacterial pathogens of livestock: light-activated CO-releasing molecules

抗生素耐药性在英国和全世界都是一个日益严重的问题。我们迫切需要找到方法来抵消细菌对人类和动物健康的抗菌素耐药性的影响。一种有希望的方法是通过新的抗生素替代品或添加剂，减少抗生素的使用，对抗耐药性，降低成本。一氧化碳（CO）是一种无色无味的气体，是一种臭名昭著的呼吸道毒药，被称为“无声杀手”，源于家用燃气器具，汽车尾气和各种工业过程。然而，它也被认为是微生物，动物和植物中重要的小信号分子（或“气体传递器”）。我们仍然对CO气体如何在炎症，心血管系统和其他地方发挥其许多重要作用知之甚少。其原因之一是难以在生物系统中递送和操纵CO剂量。当通过吸入来应用CO时，如目前在医学中所探索的，气体的最终分布难以调节，而应用于局部部位（例如微生物感染部位）几乎是不可能的。然而，因为在小剂量下，CO在生物学中具有有益和重要的作用，研究人员在过去10年中开始评估CO释放分子（CORM）作为易于处理，更安全和更有选择性的方式来管理CO。该提案的重点是CORM的抗菌应用，其中CO释放是由光（PhotoCORM）按需触发的，这样我们就可以在选定的时间将气体选择性地输送到微生物感染的部位。我们的目的是了解一般的CORMS，特别是PhotoCORMS的抗菌效果，与更成熟的抗菌化合物相比。在这个项目中，我们将：a）开发和合成新的PhotoCORM，具有更好的生物学特性，并有可能用作抗生素的替代品，或抗生素的补充剂，以对抗细菌感染。与化学家合作，我们将设计和制造改进的分子，其中CO的释放可以根据特定的需求进行调整。我们还将再次通过分子设计来改进细胞和组织的特异性靶向;B）测试这些化合物抑制感染家禽的细菌（禽病原性大肠杆菌）生长或杀死感染家禽的细菌的能力。c）了解PhotoCORM如何进入细菌细胞，以及细菌是否比动物细胞更容易吸收这些化合物;d）揭示细菌在受到这些化合物挑战时所做出的复杂反应，并确定细菌可能产生的抗性策略，这可能影响PhotoCORM作为抗微生物剂的未来用途; e）利用这一基本知识来研究这些化合物如何以及是否可以在实验室中杀死鸡的无脊椎动物发病模型中的细菌;这些研究将导致CORM的未来应用，以帮助对抗动物和人类的抗药性感染。

Antimicrobial resistance is a growing problem in the UK and worldwide. We urgently need ways to counteract the effects of the antimicrobial resistance of bacteria in human and animal health. One promising approach is through novel alternatives or additions to antibiotics, so that antibiotics are used less, resistance is countered, and costs are lowered.Carbon monoxide (CO) is a colourless and odourless gas, and an infamous respiratory poison, notorious as the 'silent killer' originating from domestic gas appliances, motor car exhausts and various industrial processes. However, it is also known to be a vital small signaling molecule (or 'gasotransmitter') in microbes, animals and plants. We still know relatively little about how CO gas exerts its many important effects in inflammation, the cardiovascular system and elsewhere. One reason for this is that it is difficult to deliver and manipulate CO doses in biological systems. When CO is applied by inhalation, as is currently being explored in medicine, the final distribution of the gas is difficult to tune, while application to localised sites, e.g. of microbial infection, is virtually impossible. However, because, in small doses, CO has beneficial and essential roles in biology, researchers have started in the last 10 years to evaluate CO-releasing molecules (CORMs) as easy-to-handle, safer and more selective ways to administer CO. Remarkably, these compounds can kill bacteria and the way they work appears entirely different from currently prescribed antibiotics. This proposal focuses on the antimicrobial applications of CORMs in which CO release is triggered on demand by light (PhotoCORMs) so that we can deliver the gas selectively to sites of microbial infection and at chosen times. We aim to understand the antibacterial effects of CORMS in general, and PhotoCORMs in particular, in comparison with more established antimicrobial compounds. In this project we will:a) Develop and synthesise new PhotoCORMs with better biological properties and potential for use as alternatives to antibiotics, or supplements to antibiotics, against bacterial infections. In collaboration with chemists, we will design and make improved molecules in which CO release can be adjusted for particular needs. We will also improve the specific targeting of cells and tissues, again by molecular design;b) Test these compounds for their ability to inhibit the growth or kill bacteria that infect poultry (avian pathogenic E. coli, APEC) by entering the cells and damaging important sites and enzymes;c) Understand how PhotoCORMs get into bacterial cells and whether bacteria take up these compounds more readily than do animal cells;d) Unravel the complex responses that bacteria make when challenged with these compounds and identify perhaps resistance strategies that the bacteria may mount and that could influence future use of PhotoCORMs as antimicrobial agents;e) Exploit this basic knowledge to study how and if these compounds can kill bacteria in in the laboratory, in invertebrate models of pathogenesis in chickens;It is intended that these studies will lead to the future application of CORMs to aid in the battle against antibiotic-resistant infections in animals and man.