Anion Carriers for Channel Replacement Therapy

常见的、缩短生命的遗传性疾病囊性纤维化(CF)的特征是有缺陷的阴离子跨细胞膜运输。这项拟议的研究旨在开发能够通过细胞膜传输阴离子的化学物质，并在安全性研究完成后准备在人体上进行测试。英国有近1.1万人患有CFs，全球有7万人患有CFs。这种疾病是由一种蛋白质-囊性纤维化跨膜电导调节因子(简称CFTR)发生故障引起的，该调节因子允许阴离子(如氯化物和碳酸氢盐)跨细胞膜运输。当cftr有缺陷或从细胞膜上消失时，体内的导管和管子会被粘稠的粘液堵塞。在肺部，这会触发感染和炎症的恶性循环，破坏肺组织，导致呼吸困难、生活质量下降和过早死亡。一种治疗CF根本原因的新方法是使用阴离子载体的CFTR替代疗法。阴离子载体是一种人工合成的小分子，旨在通过在膜的一侧拾取阴离子，携带它们，然后在另一侧释放阴离子来取代CFTR的作用。在通过吸入和插入细胞膜进入肺部后，阴离子载体可以挽救正常水平的阴离子运输，并通过一系列作用恢复健康的粘液，这些粘液很容易从肺中清除。在早期的工作中，我们和其他人已经证明，确实有可能设计插入膜中并介导跨膜负离子运输的小分子。我们的一些系统能够进行非常高的活动，接近CFTR。重要的是，一些具有类药物性质的阴离子载体能够有效地传递到细胞膜，在那里它们可以长时间工作，将阴离子输送到细胞内和细胞外，而没有毒性迹象。基于我们之前的结果，有充分的理由相信阴离子载体可以用于治疗CF。该项目将采取关键步骤来实现这一目标。这项工作将由布里斯托尔的化学家和生理学家以及澳大利亚悉尼的一个化学小组(单独资助)合作完成。最初，我们将致力于优化细胞内的活动，确定最好的候选人进行更仔细的检查。然后，我们将对组织、衬里、导管和管子(而不是单个细胞)进行一系列测试，旨在验证我们的假设，即阴离子载体可以恢复CF患者的正常功能。同时，我们将深入研究阴离子载体在合成膜和天然膜中的行为，以便生物医学的发展能够建立在坚实的基础上。这将包括选择性和机理研究，以及确定细胞内阴离子载体分布的荧光显微镜。我们还将测试新的输送系统，这些系统可以用来帮助阴离子载体到达细胞膜。在项目结束时，我们将为临床研究奠定基础，有可能导致治疗CF。

The common, life-shortening inherited disease cystic fibrosis (CF) is characterised by defective anion transport across cell membranes. The proposed research aims to develop chemicals which are capable of transporting anions across cell membranes, and are ready for testing in humans after safety studies are completed.Almost 11,000 people live with CF in the UK and >70,000 worldwide. The disease is caused by malfunction of a protein, the cystic fibrosis transmembrane conductance regulator (termed CFTR), which allows the transport of anions (e.g. chloride and bicarbonate) across cell membranes. When CFTR is faulty or missing from the cell membrane, ducts and tubes in the body become blocked by thick, sticky mucus. In the lungs, this triggers a vicious cycle of infection and inflammation that destroys lung tissue, leading to breathing difficulties, poor quality of life and premature death.A novel approach to treat the root cause of CF is "CFTR replacement therapy" using anionophores (anion carriers). Anionophores are synthetic small molecules which are designed to replace the action of CFTR, by picking up anions on one side of the membrane, carrying them across, and releasing them on the far side. After their delivery to the lungs by inhalation and insertion into cell membranes, anionophores could rescue normal levels of anion transport and, through a chain of effects, restore the healthy mucus which is easily cleared from the lungs.In earlier work, we and others have shown that it is indeed possible to design small molecules which insert into membranes and mediate transmembrane anion transport. Some of our systems are capable of very high activity approaching that of CFTR. Importantly, a few anionophores, with drug-like properties, are capable of efficient delivery to cell membranes, where they work for prolonged periods, transporting anions into and out of cells, without signs of toxicity.Based on our previous results, there is good reason to believe that anionophores could be used to treat CF. This project will take critical steps towards realising this goal. The work will be performed by a collaboration involving chemists and physiologists in Bristol, and a chemistry group in Sydney, Australia (funded separately). Initially we will work towards optimising activity in cells, identifying the best candidates for closer examination. We will then apply a series of tests on tissues lining ducts and tubes (as opposed to individual cells) designed to validate our hypothesis that anionophores can restore normal function in CF patients. Meanwhile we will perform in-depth studies on anionophore behaviour, in both synthetic and natural membranes, so that biomedical development can rest on firm foundations. This will include selectivity and mechanistic investigations, as well as fluorescence microscopy to ascertain anionophore distribution in cells. We will also test new delivery systems which could be used to help anionophores reach cell membranes. At the end of the project we will have set the stage for clinical studies, potentially leading to treatments for CF.