Centre for Biomedical Modelling and Analysis, Living Systems Institute, University of Exeter, Exeter, EX4 4QD, United Kingdom. Department of Life Sciences, Imperial College, London, SW7 2AZ, United Kingdom.
Rep Prog Phys. 2017 Dec;80(12):126601. doi: 10.1088/1361-6633/aa8730.
Phagocytosis is a fascinating process whereby a cell surrounds and engulfs particles such as bacteria and dead cells. This is crucial both for single-cell organisms (as a way of acquiring nutrients) and as part of the immune system (to destroy foreign invaders). This whole process is hugely complex and involves multiple coordinated events such as membrane remodelling, receptor motion, cytoskeleton reorganisation and intracellular signalling. Because of this, phagocytosis is an excellent system for theoretical study, benefiting from biophysical approaches combined with mathematical modelling. Here, we review these theoretical approaches and discuss the recent mathematical and computational models, including models based on receptors, models focusing on the forces involved, and models employing energetic considerations. Along the way, we highlight a beautiful connection to the physics of phase transitions, consider the role of stochasticity, and examine links between phagocytosis and other types of endocytosis. We cover the recently discovered multistage nature of phagocytosis, showing that the size of the phagocytic cup grows in distinct stages, with an initial slow stage followed by a much quicker second stage starting around half engulfment. We also address the issue of target shape dependence, which is relevant to both pathogen infection and drug delivery, covering both one-dimensional and two-dimensional results. Throughout, we pay particular attention to recent experimental techniques that continue to inform the theoretical studies and provide a means to test model predictions. Finally, we discuss population models, connections to other biological processes, and how physics and modelling will continue to play a key role in future work in this area.
吞噬作用是一个令人着迷的过程，在此过程中，细胞会包围并吞噬细菌和死细胞等颗粒。这对于单细胞生物（作为获取营养的一种方式）和免疫系统（以消灭外来入侵者）都是至关重要的。整个过程非常复杂，涉及多个协调事件，如膜重塑、受体运动、细胞骨架重组和细胞内信号转导。正因为如此，吞噬作用是理论研究的绝佳系统，受益于生物物理方法与数学建模的结合。在这里，我们回顾这些理论方法，并讨论最近的数学和计算模型，包括基于受体的模型、关注相关力的模型，以及考虑能量因素的模型。在这个过程中，我们强调了与相变物理之间的美丽联系，考虑了随机性的作用，并研究了吞噬作用与其他类型胞吞作用之间的联系。我们涵盖了吞噬作用的最近发现的多阶段性质，表明吞噬杯的大小以不同的阶段生长，初始阶段较慢，随后是大约一半吞噬时开始的快得多的第二阶段。我们还解决了目标形状依赖性的问题，这与病原体感染和药物输送都有关，涵盖了一维和二维的结果。自始至终，我们特别关注不断为理论研究提供信息并提供测试模型预测手段的最新实验技术。最后，我们讨论了群体模型、与其他生物过程的联系，以及物理和建模将如何继续在该领域的未来工作中发挥关键作用。
