Synthetic Anion Carriers for Biomedical Applications

囊性纤维化（CF）是最常见的遗传性疾病之一。像许多这类疾病一样，它是由一种特殊蛋白质——囊性纤维化跨膜传导调节因子（CFTR）的功能障碍引起的。在正常人中，CFTR存在于细胞膜中，作为阴离子（如氯离子）进入或离开细胞的通道。它在肺部的作用尤其重要，因为这种阴离子的流动有助于维持保持肺部清洁的系统。如果CFTR缺失或不能正常工作，肺部就会充满粘稠的粘液，容易受到感染。在英国，CF患者通常在30岁之前死于肺部疾病。一种可能的CF治疗方法是通道替代疗法。原则上，肺里的细胞可以通过合成化合物来模拟CFTR的作用，允许阴离子穿过细胞膜。由于缺乏合适的化合物，这个想法很难付诸实践。然而，我们最近发现了一个分子家族，称为胆足类，它具有必要的特性。首先，它们主要是由碳氢化合物构成的，因此存在于细胞膜而不是水溶液中。其次，它们对阴离子（如氯离子）有很高的亲和力，它们可以从水中提取阴离子。第三，它们可以携带阴离子穿过细胞膜。通过在一侧结合氯离子并在另一侧释放它们，它们允许阴离子穿过膜，模拟CFTR的整体作用。开发胆足类或相关的阴离子载体（阴离子载体）用于CF治疗似乎是一个真正的前景。然而，在考虑完整的生物医学计划之前，还需要进一步的研究。我们需要在关键方面进行优化的阴离子载体（作为载体的有效性，低毒性，易于传递到细胞）。我们还需要证明它们可以在天然细胞膜中运作，以及在我们大多数实验中使用的更简单的合成模型。我们将首先完成对合成膜中胆足类动物的全面研究。特别是，我们将使用电气方法来详细了解运输过程。我们特别感兴趣的是找出哪一步（阴离子提取，跨膜运动等）是最慢的，因此是决定速率的。然后我们可以努力改进这一步。我们还将准备和研究一系列新的例子，这样我们就可以确定结构-活性关系。通过结合这两种方法，我们将确定生物学研究的最佳胆足类。我们还将探索一些新颖的、受胆足虫启发的结构。这些包含原始设计的关键特征，但在可能提高性能的方式上有所不同（例如，通过加速膜的运动）。一旦阴离子载体在合成膜中得到优化，它们将在自然系统中进行测试。在单个细胞的电学研究之后，将在培养的上皮细胞（模拟肺内壁的细胞层）中进行实验。我们将对毒性和其他与药物有关的特性（吸收、代谢等）进行初步测试。如果结果是有利的，这些研究应该为CF患者的阴离子载体通道替代疗法提供主要证据。

Cystic fibrosis (CF) is one of the most common genetic diseases. Like many such illnesses, it is caused by the malfunction of a particular protein, the Cystic Fibrosis Transmembrane Conductance Regulator (or CFTR). In normal people CFTR resides in the membranes of cells and serves as a channel through which anions, such as chloride ions, can enter or leave the cell. Its role is especially important in the lungs, as this flow of anions helps to maintain the system which keeps the lungs clean. If the CFTR is missing, or fails to work properly, the lungs become full of sticky mucous and vulnerable to infection. In the UK, patients with CF usually die from lung disease before the age of 30.A possible approach to CF treatment is channel replacement therapy . In principle, the cell in the lungs could be provided with synthetic compounds which would mimic the action of CFTR, allowing anions to pass through the membranes. The idea has been difficult to try out, because of a lack of suitable compounds. However, we have recently discovered a family of molecules, termed cholapods , which have the necessary properties. Firstly they are made largely of hydrocarbon, and will therefore locate in cell membranes rather than aqueous solution. Secondly they have high affinities for anions such as chloride, which they can extract from water. Thirdly they can move through the membranes, carrying the anions with them. By binding chloride ions on one side and releasing them on the other, they allow the anions to cross the membrane, mimicking the overall action of CFTR. There seems a genuine prospect for developing cholapods, or related anionophores (anion carriers), into treatments for CF. However, further studies are necessary before a full biomedical programme can be considered. We need anionophores which are optimised in key respects (effectiveness as carriers, low toxicity, ease of delivery to cells). We also need to show that they can operate in natural cell membranes, as well as the simpler synthetic models used in most of our experiments. We will begin by completing a full study of the cholapods in the synthetic membranes. In particular, we will use electrical methods to achieve a detailed understanding of the transport process. We are especially interested in finding out which step (anion extraction, movement across membrane etc.) is the slowest, and is therefore rate-determining . We can then work to improve this step. We will also prepare and study a range of new examples, so that we can determine structure-activity relationships. By combining the two approaches we will identify optimal cholapods for biological studies. We will also explore some novel, cholapod-inspired structures. These contain key features of the original design, but are different in ways which might improve performance (e.g. by speeding up movement through the membrane).Once the anionophores have been optimised in synthetic membranes, they will be tested in natural systems. Electrical studies in individual cells will be followed by experiments in cultured epithelia (layers of cells which mimic the lining of the lungs). We will perform preliminary tests for toxicity and other properties relating to druggability (absorption, metabolism etc.). If results are favourable, these studies should provide proof of principal for anionophore-based channel replacement therapy for CF patients.