Written by:
Erwin De Genst,
Senior Scientist, Biologics Engineering, R&D, AstraZeneca
Kylie Foo,
Assistant Professor, Karolinska Institutet
心力衰竭(HF)是一种危及生命的疾病，发生在心脏不能向全身泵出足够的血液时. It affects 64 million people worldwide,1 and is a leading cause of death and hospitalisation. 对一种能够解决HF心功能障碍根本原因的治疗的需求仍然很高.
心力衰竭的特征之一是钙信号缺陷. 钙在心肌的收缩和松弛中起着不可或缺的作用.
每次心跳时，细胞内钙升高，导致肌肉细胞收缩. This is followed by a rapid decrease in calcium, which leads to relaxation, preparing the cells to produce the next heartbeat.
钙的运动是由心脏细胞表面和内部的钙处理蛋白质促进的，当它们与其他蛋白质相互作用时，会经历复杂的动态转变.
钙处理蛋白之间错误的相互作用破坏了正常的钙信号传导, impairing contraction and relaxation of the heart muscle. 这可能会导致危险的心律失常和结构变化, which may ultimately result in heart failure and death.
通过阻断蛋白质抑制剂，增强钙循环和心脏功能
Sarco/endoplasmic reticulum calcium ATPase, known as ‘SERCA’ is a key protein involved in calcium cycling. 它将钙从细胞质转运到肌浆网，在肌浆网中钙储存在心肌中. SERCA的活性受其与磷蛋白的相互作用调节 or ‘PLN’, a protein that inhibits calcium cycling in the heart. By binding to SERCA, PLN控制着钙从细胞质中移除的速度和细胞内储存钙的量.
Patients with heart failure tend to have reduced levels of SERCA, and comparatively high levels of PLN, leading to too few active SERCA molecules. This results in slow heart muscle relaxation and weak contractions. Enhancing calcium cycling by blocking or disrupting PLN could, therefore, improve the ability of the heart to pump blood.
VHH intrabodies shown to disrupt the action of PLN
以前，曾尝试使用小分子药物破坏PLN的活性. However, 这种方法被证明是不成功的，因为PLN是灵活的，存在于不同结构形式之间的动态平衡中，缺乏明确的定义, accessible ‘pockets’ in its structure, which drug molecules usually need in order to be effective.
However, in our latest research, published in Nature Communications, 澳门第一赌城在线娱乐已经找到了一种破坏PLN的方法-使用VHH体内体-它来源于天然存在的骆驼重链抗体的抗原识别结构域.2
澳门第一赌城在线娱乐从一个合成文库中鉴定出与PLN结合并阻止PLN单体与SERCA结合的强效vhs, enhancing its activity. By linking two identical copies of the VHHs together, 澳门第一赌城在线娱乐发现这些二聚体vhs通过增加无活性PLN五聚体的水平进一步增加了SERCA的活性.
然后，澳门第一赌城在线娱乐使用化学修饰的信使RNA -在细胞内具有增强稳定性的合成信使分子-来验证vhh对抗PLN的有效性 in vitro, using isolated live heart cells.
研究结果表明，体内VHH有助于恢复正常的钙循环, 恢复心力衰竭小鼠心脏的正常泵血功能.
aav递送的体内VHH可能导致新的心力衰竭治疗
使用腺相关病毒(aav)给药以前已被证明是有效的 in vivo delivery of extracellular biotherapeutics, 所以这些平台提供了一个评估体内输送的机会.
澳门第一赌城在线娱乐使用心脏靶向的AAV载体，在心肌细胞特异性启动子的控制下表达vhh. 用于心脏靶向体内递送的AAV载体通过全身给药实现组织选择性表达, minimising the risk of damage to non-relevant tissues. 注射到临床前模型中，有效地表达了在心脏中的特异性体内蛋白, with no detection in the liver or any other muscle tissue.
这项研究表明，体内VHH可能为心力衰竭的潜在新疗法打开大门, 特别是当与新兴的基于病毒或基于核酸的药物输送技术相结合时，它可能最终使澳门第一赌城在线娱乐离阻止心脏衰竭更近一步.
“This work shows the utility of mRNA approaches, normally viewed as a 'gain of function platform', 快速筛选和识别纳米体和其他‘功能丧失’治疗候选物。. Chien, Professor of Cardiovascular Research at Karolinska Institutet.
