JOINT EPSRC/MRC CHEMICAL BIOLOGY Pharmacological targeting of cytosolic calpain-1: The development of novel inhibitors

白细胞，如中性粒细胞和淋巴细胞，通过离开血液循环进入组织并摧毁感染的微生物来对抗感染。然而，在一些炎症性疾病中，这些细胞是问题的原因。例如，在类风湿性关节炎中，白细胞不断离开血流，迁移到受影响的关节，在那里它们被不适当地激活以攻击？关节的组织。这会导致关节的渐进性破坏。不出所料，人们已经做出了相当大的努力来试图了解白细胞离开血流的机制，以便设计出有效的治疗方法来阻止这种情况。其中一个成功之处就是使用了单抗来阻断分子信号。白血球离开血流。然而，这种方法也存在问题。首先，治疗需要昂贵的抗体输注，必须在医院进行。其次，抗体是高度选择性的，只能识别并阻断一组分子。因为可能有一系列的分子在呼唤？对白细胞来说，任何一种单抗都可能失效。因此，我们研究了白细胞如何离开血流的机制，因为这肯定是一种常见的事件，无论确切地说涉及到哪些调用分子。我们发现，为了穿过血管壁，细胞会改变形状。这涉及到细胞表面积的明显增加。我们有证据表明，这种情况的发生是因为细胞的细胞膜最初非常皱折。当将它们连接在一起的蛋白质链接被一种名为calain-1的酶打破时，这些皱纹就会展开。如果这种酶被抑制，这种展开就会停止，白细胞离开血液的速度就会大大降低。这将是一种可以简单口服的抗炎药的基础。幸运的是，我们已经知道一些合成分子可以抑制这种酶。此外，我们知道它们与酶结合的位置。在这个项目中，我们计划利用这些知识来？量身定制？这一家族的分子将变得更有效和更具选择性，只对Calain-1有作用。这将最大限度地减少因抑制其他酶而产生不良副作用的可能性，这些酶也会切割蛋白质。

White blood cells, such as neutrophils and lymphocytes combat infection by leaving the blood circulation to enter the tissues and destroy infecting microbes. However, there are a number of inflammatory disease in which these cells are the cause of the problem. In rheumatoid arthritis, for example, white cells continually leave the blood stream and migrate to the affected joints, where they are inappropriately activated to ?attack? the tissues of the joint. This causes a progressive destruction of the joint. Unsurprisingly, considerable effort has been made in trying to understand the mechanism by which white cells leave the blood stream so that effective treatments can be devised to stop this. One of the successes has been the use of monoclonal antibodies to block the molecular signals which ?call? white cells to leave the blood stream. However there are problems, with this approach. Firstly, the treatment involves a costly infusion of antibody which must be done in hospital. Secondly, antibodies are highly selectively and can only recognise, and so block, one set of molecules. Since there may be a range of molecules ?calling? to the white cells, any single monoclonal antibody may fail to be effective. We have therefore looked at the mechanics of how the white cells leave the blood stream, because this must be a common event regardless of precisely which calling molecules are involved. We have found that the cells change shape in order to slip through the blood vessel walls. This involves an apparent large increase in the surface area of the cells. We have evidence that this occurs because the membrane of the cells is initially very wrinkled. These wrinkles unfurl when the protein links which hold them together are broken by an enzyme called calpain-1. If this enzyme is inhibited, the unfurling stops and the speed which white cells can leave the blood is greatly reduced. This would be the basis for an anti-inflammatory drug which could be simply taken by mouth. Luckily, we already know of some synthetic molecules which inhibit the enzyme. Furthermore, we know where they bind to the enzyme. In this project, we plan to use this knowledge to ?tailor? this family of molecules to become more potent and selective only for calpain-1. This will minimise the possibility of unwanted side effects by inhibition of other enzymes which also cut proteins.