Decoding how neutrophils self-organise their migration to sites of infection in vivo (360G-Wellcome-105391_Z_14_Z)

Neutrophils are key effectors of antibacterial immunity and inflammation. These cells often migrate in a highly co-ordinated and directed manner in order to reach sites of infection. This so-called ‘swarming’ response was shown to depend on self-production of the neutrophil attractant, LTB4. However, the cellular dynamics underlying transition from exploratory, single cell migration to collective and highly directional migration remain unclear. To address this knowledge gap I will use in vivo imaging and genetic manipulations in a zebrafish model. I will first determine the cellular triggers for LTB 4 production by neutrophils in situ. For this I will make transgenic fish expressing a reporter probe for LTB 4 production. Then I will investigate how LTB4 autocrine/paracrine signalling directs neutrophil polarity and migration. For this I will directly monitor autocrine/paracrine signalling using an additional probe for LTB 4 sensing. Finally I aim to spatiotemporally manipulate LTB 4 production and neutrophil swarming in vivo. To this end, I will develop an optogenetic tool to control the production of LTB 4 by light and use this to establish the implications of neutrophil swarming in microbial defence and tissue integrity. Thus, this study will provide a better understanding of how neutrophils self-organise their migration to sites of infection