Enabling immunotherapy through the detection and sequestration of CO by fluorogenic probes

该项目旨在开发一种新的水兼容探针家族，能够荧光检测细胞和体内内源性产生的少量一氧化碳（CO）。这种产生主要是由于血红素加氧酶（HO-1）对血红素的分解代谢，抑制这种酶与人类更好的化疗结果有关。这些探针将用于询问CO在抑制肿瘤免疫反应中的作用，从而使这种小分子在体外和体内的可视化。将这种方法应用于临床，可以估计CO的产生作为HO-1表达的函数，用于衡量患者对化疗的可能反应，作为辅助免疫反应的一部分。癌症免疫疗法利用免疫系统来攻击和根除癌症。为了实现这一点，需要研究肿瘤微环境中抑制免疫反应的机制，光学方法（例如荧光成像）非常适合研究这一点。肿瘤免疫抑制是临床上允许有效的癌症免疫治疗的主要障碍（Arnold， Ng等，Nature Comm. 2018, 9,1）。血红素加氧酶-1 （HO-1）在多种肿瘤中表达，在血红素分子的酶降解过程中产生一氧化碳（CO）。除了作为一种气体传递素的许多其他调节细胞作用外，CO具有免疫抑制作用，可以损害肿瘤微环境中的t细胞反应，阻止肿瘤的细胞溶解杀死。然而，在细胞内和体内对CO的检测和实时跟踪需要探针合成简单、坚固、无细胞毒性以及对CO的高灵敏度和选择性。Wilton-Ely （JWE）小组开发了一系列基于钌和锇的探针，用于选择性检测空气中的CO （J. Am.）。化学。社会科学学报，2014,136,11930)和细胞（J. Am.）。化学。Soc. 2017, 139, 18484)。检测系统是基于一氧化碳配体对金属中心的极高亲和力，导致快速和选择性结合和非常低的检测限（1 ppb）。这些复合物表现出优异的稳定性，没有细胞毒性。这已经在一个真实的（皮下气囊）小鼠模型中对内源性CO的体内生产响应炎症的监测中得到了证明。化学。Soc. 2017, 139, 18484)。然而，需要新的探针设计，它具有更好的溶解度和发射特性，并且可以针对细胞中与CO生成相关的特定特征（例如，线粒体）。博士项目将涉及配体合成、配位化学、组织培养、细胞荧光测量和动物模型翻译（与KCL肿瘤免疫学组James Arnold博士合作）。

This project aims to develop a new family of water-compatible probes that are able to fluorogenically detect the small amounts of carbon monoxide (CO) produced endogenously in cells and in the body. This production is largely due to the catabolism of haem by haem oxygenase (HO-1) and the inhibition of this enzyme is associated with better chemotherapy outcomes in humans. These probes will be used to interrogate the effect of CO in suppressing the immune response towards tumours, allowing the visualisation of this small molecule in vitro and in vivo. Translation of this approach into the clinic could allow the estimation of CO production as a function of HO-1 expression to be used to gauge the likely response of patients towards chemotherapy as part of an assisted immune response.Cancer immunotherapy harnesses the immune system to attack and eradicate cancer. For this to be achieved, the mechanisms which are exploited within the tumour microenvironment to suppress immune responses need to be investigated and optical methods (e.g., fluorescence imaging) are well-suited to study this. Tumoural immune suppression is a major hurdle to permitting effective cancer immunotherapy in the clinic (Arnold, Ng et al, Nature Comm. 2018, 9, 1). The enzyme haem oxygenase-1 (HO-1), which is expressed in a variety of tumours, generates carbon monoxide (CO) in its enzymatic degradation of the molecule haem. Alongside many other regulatory cellular roles as a gasotransmitter, CO is immune suppressive and can compromise T-cell responses in the tumour microenvironment, preventing cytolytic killing of the tumour. However, the detection and real-time tracking of CO in cells and in vivo requires probes that are synthetically-straightforward, robust, non-cytotoxic as well as being highly sensitive and selective for CO.The Wilton-Ely (JWE) group has developed a series of probes based on ruthenium and osmium for the selective detection of CO in air (J. Am. Chem. Soc. 2014, 136, 11930) and in cells (J. Am. Chem. Soc. 2017, 139, 18484). The detection system is based on the extremely high affinity of carbon monoxide ligand for the metal centre, leading to rapid and selective binding and very low detection limits (1 ppb). These complexes show excellent stability and are not cytoxic. This has been illustrated in the monitoring of in vivo production of endogenous CO in response to inflammation in a realistic (subcutaneous air pouch) mouse model (J. Am. Chem. Soc. 2017, 139, 18484). However, new probe designs are needed, which have improved solubility and emission properties and can target particular features in the cells (e.g., mitochondria), associated with CO generation.The PhD project will involve ligand synthesis, coordination chemistry, tissue culture, fluorescence measurements in cells and translation to animal models (with Dr James Arnold, Tumour Immunology Group, KCL).