Characterising neutrophil reverse migration using wet and dry experimentation

中性粒细胞是人类白细胞的主要类型，是天然免疫系统的组成部分。一旦激活，它们就会沿着趋化因子的梯度移动到感染或损伤的地方，这一过程称为趋化作用。一旦到达那里，它们就会执行效应器功能(如吞噬、释放ROS)，然后通过细胞凋亡而死亡。中性粒细胞反向迁移，或逆行趋化，是指远离感染或损伤部位，与吸引趋化因子的梯度相反。它已经在体外和体内得到了描述，并且与现有的中性粒细胞行为教条相反。这一过程可能与炎症消退有关，但已被证明具有病理方面的作用，促进了远端部位的炎症，如肺部。它被认为与类风湿性关节炎和慢性阻塞性肺疾病等慢性炎症性疾病有关。本项目将通过计算模拟和湿实验室方法相结合的方法来研究控制中性粒细胞反向迁移的分子机制。基础中性粒细胞和迁移后的中性粒细胞将使用为该项目优化的定制趋化分析进行检查。他们的趋化行为以及不同的趋化因子和受体的表达将进行比较。计算模型将被用来寻找和扩展趋化因子和其他有吸引力的分子的新陈代谢可以将它们从吸引剂转变为排斥剂的方法，并将被用于定义更有信息量的实验设置，其结果将反过来用于测试和进一步完善模型。有几种可能性需要解决：趋化物质的分解是否介导了反向迁移？化学引诱剂会变成化学抵抗剂吗？反向迁移是否涉及受体脱敏？中性粒细胞一旦被招募到感染部位后会发生变化吗？该项目将致力于确定中性粒细胞反向迁移如何在治疗上具有靶向性。

Neutrophils are the predominant type of leukocyte in humans and form an integral part of the innate immune system. Upon activation, they move to the site of infection or injury, following gradients of chemokines in a process called chemotaxis. Once there, they perform effector functions (e.g. phagocytosis, release of ROS) before dying by apoptosis. Neutrophil reverse migration, or retrograde chemotaxis, is the movement away from the site of infection or injury and opposite to the attracting chemokine gradient. It has been described in vitro and in vivo, and is contrary to existing dogma of neutrophil behaviour. The process may be involved in inflammation resolution, but has been shown to have a pathologic aspect, promoting inflammation at distal sites such as the lungs. It is thought it could be implicated in chronic inflammatory diseases such as rheumatoid arthritis and COPD.This project will investigate the molecular mechanisms controlling neutrophil reverse migration by combining computational modelling with wet lab methods. Basal and post-migrated neutrophils will be examined using bespoke chemotaxis assays optimised for this project. Their chemotactic behaviour and differential chemokine and receptor expression will be compared. Computational modelling will be used to find and expand ways in which metabolism of chemokines and other attractive molecules can turn them from attractants into repellents and be used to define more informative experimental set-ups, the results of which will in turn be used to test and further refine the model. There are several possibilities to be addressed: Does chemoattractant break-down mediate reverse migration? Do chemoattractants turn into chemorepellents? Does reverse migration involve receptor desensitization? Do neutrophils change once they have been recruited to a site of infection? This project will work towards identifying how neutrophil reverse migration could be therapeutically targeted.