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

在英国和全世界，抗菌素耐药性是一个日益严重的问题。我们迫切需要方法来抵消细菌的抗菌素耐药性对人类和动物健康的影响。一种有希望的方法是通过抗生素的新替代品或添加剂，从而减少抗生素的使用，对抗耐药性，并降低成本。一氧化碳(CO)是一种无色无味的气体，也是一种臭名昭著的呼吸道毒素，被认为是来自家用燃气用具、汽车尾气和各种工业过程的臭名昭著的“沉默杀手”。然而，在微生物、动物和植物中，它也是一种重要的小信号分子(或“气体传递器”)。我们对CO气体如何在炎症、心血管系统和其他方面发挥其许多重要作用的了解仍然相对较少。其中一个原因是很难在生物系统中传递和控制一氧化碳剂量。当通过吸入方式应用一氧化碳时，正如目前医学上正在探索的那样，气体的最终分布很难调整，而应用于局部部位，例如微生物感染，实际上是不可能的。然而，由于小剂量的CO在生物学上具有有益和必要的作用，研究人员在过去10年里开始评估CO释放分子(COMMS)是一种易于操作、更安全和更有选择性的CO给药方式。值得注意的是，这些化合物可以杀死细菌，它们的作用方式似乎与目前开出的抗生素完全不同。这项建议侧重于球茎的抗菌应用，在球茎中，CO的释放在光的需求下被触发(PhotoCORms)，这样我们就可以有选择地在选定的时间将气体输送到微生物感染的部位。我们的目标是了解球茎的抗菌作用，特别是PhotoCORM，与更成熟的抗菌化合物进行比较。在这个项目中，我们将：a)开发和合成具有更好生物学特性的新的PhotoCORM，并有可能用作抗生素的替代品或抗生素的补充，以对抗细菌感染。在与化学家的合作下，我们将设计和制造改进的分子，其中的CO释放可以根据特定需求进行调整。我们还将提高针对细胞和组织的特异性，同样是通过分子设计；b)测试这些化合物是否有能力通过进入细胞并破坏重要部位和酶来抑制感染家禽(禽类致病性大肠杆菌，APEC)的细菌的生长或杀死细菌；c)了解PhotoCORM是如何进入细菌细胞的，以及细菌是否比动物细胞更容易吸收这些化合物；d)解开细菌在受到这些化合物挑战时做出的复杂反应，并确定细菌可能安装的抗药性策略，这可能会影响PhotoCORM作为抗菌剂的未来使用；E)利用这一基本知识，研究这些化合物如何以及是否可以在实验室中、在鸡的无脊椎动物致病模型中杀死细菌；目的是这些研究将导致未来应用球茎来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.